Glutamate

Plasmalogens Week #7 – Genes

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Continuing Plasmalogens Week with three 2025 papers, starting with a rodent study of genetically deleting a plasmalogen catabolizing enzyme:

“In this study, we investigated the impact of global and tissue-specific loss-of-function of a plasmalogen catabolizing enzyme, lysoplasmalogenase (TMEM86B), on circulatory and tissue lipidomes. Mice with homozygous global inactivation of Tmem86b (Tmem86b KO mice) were viable and did not display any marked phenotypic abnormalities.

Tmem86b KO mice demonstrated significantly elevated levels of plasmalogens alkenyl phosphatidylethanolamine (PE(P)) and alkenyl phosphatidylcholine (PC(P)), as well as lysoplasmalogens, in the plasma, liver, and natural killer cells compared to their wild-type counterparts. The endogenous alkenyl chain composition of plasmalogens remained unaltered in Tmem86b KO mice. Consistent with the global knockout findings, hepatocyte-specific Tmem86b knockout mice also exhibited increased plasmalogen levels in the plasma and liver compared to their floxed control counterparts.

Plasmalogens may be synthesized locally within various tissues, with each organ possessing the necessary enzymatic machinery to regulate its own plasmalogen levels. Plasmalogens are important structural constituents of the biological membranes of animals and certain anaerobic bacteria, and have several well-described functions, including regulating membrane dynamics and vesicular cholesterol transport and homeostasis.

  • One of the most interesting features of plasmalogens is their endogenous antioxidant activity, which is mostly due to the vinyl ether bond, which can scavenge reactive oxygen species and thereby protect other biomolecules from oxidative damage.
  • They increase the gene expression of multiple antioxidant enzymes to protect against chemically induced cytotoxicity and lipid peroxidation in cultured hepatocytes.
  • Plasmalogen derivatives such as polyunsaturated fatty acids (AA or DHA) and lysoplasmalogens can act as lipid mediators for multiple cellular signaling activities.
  • Plasmalogens are important for phagocytosis of macrophages, lipid droplet formation, and development and function of neuromuscular junctions.
  • They play vital roles in mediating immune responses, and mitochondrial fission to regulate adipose tissue thermogenesis, and protecting neuronal cells against cell death and inflammation.

All of these are suggestive of a critical role played by plasmalogens in maintaining cellular homeostasis.

While plasmalogen anabolism is well defined, its catabolism has been less studied. During catabolism, plasmalogens are deacylated by the action of a calcium-independent phospholipase A2 enzyme (iPLA2) to produce lysoplasmalogens. However, cytochrome C has also been shown to act as a plasmalogenase under certain circumstances.

The amount of lysoplasmalogens in cells is tightly regulated either by reacylation into plasmalogens through a coenzyme A-independent transacylase, or by degradation into fatty aldehydes and glycerophospholipids by an alkenyl ether hydrolase commonly known as lysoplasmalogenase. Lysoplasmalogenase is a microsomal transmembrane enzyme highly specific for lysoplasmalogens, and has no activity against plasmalogens.

While research on the distinct biological functions of lysoplasmalogens and plasmalogens is lacking, some reports indicate potential toxic effects of lysoplasmalogens. Degradation products of lysoplasmalogens, such as fatty aldehydes, are highly reactive electrophilic compounds that can form toxic adducts with cellular proteins and lipids. These interactions can lead to cellular dysfunction and contribute to various pathological conditions. Their accumulation in ischemic/reperfused tissues has been associated with cellular damage.

However, we observed that the amount of lysoplasmalogens as a proportion of total plasmalogens in the liver of Tmem86b KO mice was only ∼3.5%, indicating that elevated lysoplasmalogens are rapidly converted into plasmalogens within the liver. In adipose tissue-specific Tmem86a KO mice, which also exhibited higher lysoplasmalogens, no toxic effects were observed. Instead, these mice showed elevated mitochondrial oxidative metabolism and energy expenditure, offering protection from high-fat diet-induced metabolic dysfunction. These findings suggest that any potential toxic effects of lysoplasmalogens are largely mitigated by their rapid reacylation into plasmalogens.

This study enhances our understanding of regulatory mechanisms governing plasmalogen metabolism, and highlights the potential of targeting Tmem86b to therapeutically raise plasmalogen levels.”

https://www.jlr.org/article/S0022-2275(25)00068-9/fulltext “Modulation of endogenous plasmalogens by genetic ablation of lysoplasmalogenase (Tmem86b) in mice”

An independent researcher published a commentary on the above study:

“While the biosynthesis of this particular lipid subclass, starting in the peroxisomes and ending at the endoplasmic reticulum, has been the subject of extensive research, the degradation pathway of these compounds remains to be further elucidated. Plasmalogen breakdown is a complex process involving enzymatic hydrolysis, oxidative cleavage, and possibly also a recycling mechanism.

A fundamental unresolved question in the field of plasmalogen catabolism is which of the two possible reaction routes is actually the more important one. Either 1) directly via plasmalogenase or 2) via a deacylation step by a plasmalogen-specific phospholipase A2 (cPLA2, PLA2G4A), yielding a lysoplasmalogen as the first degradation product, and subsequent hydrolysis of the ether bond by a lysoplasmalogenase such as TMEM86A and TMEM86B. It is also unclear how these pathways interact or compensate for each other, how they are regulated, and whether they are tissue- or cell type–specific.

To make the story even more complex, a CoA-independent transacylase activity was described that reacylates lysoplasmalogen intermediates back to plasmalogens by transferring polyunsaturated fatty acids to the vacant sn-2 position of ether lysophospholipids. But no gene for this enzyme has so far been identified.

Why is plasmalogen breakdown so important? Disturbances in plasmalogen metabolism are associated with several human disorders. Neurodegenerative diseases such as Alzheimer’s disease, Parkinson’s disease, and multiple sclerosis have been shown to be associated with reduced levels of plasmalogens.

Unfortunately, it is still too early to draw conclusions about the individual roles of TMEM86A and TMEM86B, as their cellular localisation and function are not sufficiently studied, and reliable antibodies for these proteins are not yet available. Localization of the two TMEM86 homologs overlaps to some extent, as shown, for example, by their gene expression in small intestine. However, whether one isoform is able to compensate for a deficiency in the other is uncertain, and was not found in small intestine of Tmem86b knockout mice [in the above study].

In contrast to the two proteins TMEM86A and TMEM86B, cytochrome c is much better studied. It is associated with the inner mitochondrial membrane, and can be released into the cytosol during apoptosis. It has a wide tissue distribution with most abundant gene expression levels in the digestive tract and heart.“

https://www.jlr.org/article/S0022-2275(25)00074-4/fulltext “Plasmalogen. Quo vadis?”

The statement “no gene for this enzyme has so far been identified” revealed a paradigm. But maybe what’s being observed evolved before genes?

One example of this principle is from the 1966 https://www.science.org/doi/10.1126/science.152.3720.363 “Evolution of the Structure of Ferredoxin Based on Living Relics of Primitive Amino Acid Sequences” which provided evidence pointing to heme protein evolution beginning before gene evolution. Its abstract included this statement:

“We explain the persistence of living relics of this primordial structure by invoking a conservative principle in evolutionary biochemistry: The processes of natural selection severely inhibit any change in a well-adapted system on which several other essential components depend.”

Maybe the process of reassembling plasmalogen breakdown products back into plasmalogens without involving a specific gene likewise became essential?

A role of plasmalogens in diabetic kidney disease was found in a third study that investigated a genetic rodent model of diabetes:

“Diabetic nephropathy (DN) represents a frequent cardiovascular complication of diabetes, affecting about 20–50% of individuals with the disease. Globally, it constitutes a primary etiology for end-stage kidney disease (ESKD) and chronic kidney disease (CKD), while also serving as a significant independent risk factor for cardiovascular morbidity and mortality.

Although intensive management strategies targeting blood pressure and glucose levels demonstrably attenuate the risk of DN development, they do not confer complete protection. This residual risk strongly implicates pathogenic factors beyond impaired glucose metabolism and hemodynamic alterations in DN pathogenesis.

In the present study, we employed the db/db mice as the DN model. When compared to other diabetes models, such as those induced by streptozotocin (STZ) or high-fat diet combined with STZ, the db/db model more accurately recapitulates the pathological features of human type 2 diabetes mellitus (T2DM). It also possesses a stable genetic background, making it particularly well-suited for the investigation of diabetes complications.

Transcriptomics revealed extensive dysregulation of metabolic and lipid regulatory pathways in db/db. Lipidomics uncovered pronounced abnormalities in cardiolipin species composition and plasmalogen profiles. Transcriptome-lipidome integration demonstrated impaired phosphatidylcholine (PC) biosynthesis, mechanistically linked to dysregulation of choline phosphotransferase 1 (chpt1), which correlated significantly with compromised tissue regeneration capacity.

Volcano plot analysis delineated specific lipid alterations, particularly in plasmalogen species in plasmalogen lipids. Plasmenylcholines (plas-PC) and plasmenylethanolamine (plas-PE) containing n-3 polyunsaturated fatty acids (PUFAs) were significantly decreased in the kidneys of db/db mice. Conversely, plas-PCs and plas-PEs esterified with n-6 PUFAs showed substantial accumulation in diabetic kidneys.

In conclusion, the highly sensitive and extensively targeted UHPLC-MS/MS methodology enabled a more in-depth characterization of renal metabolic and lipid perturbations in db/db mice. These alterations principally reflect the sustained inflammatory milieu and compromised antioxidant defenses characteristic of DN renal tissues.”

https://www.csbj.org/article/S2001-0370(25)00301-0/fulltext “Multi-omics characterization of diabetic nephropathy in the db/db mouse model of type 2 diabetes”

Plasmalogens Week #5 – Health and Diseases, Part 1

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Continuing Plasmalogens Week with three 2025 papers, starting with a human study that included plasmalogen biomarkers of non-communicable disease fatigue symptoms:

“This study explored the biological mechanisms underlying fatigue in patients with NCDs using a multi-omics approach. Our findings indicate that distinct metabolic pathways, salivary microbiota, and genetic factors may contribute to different dimensions of fatigue, including general, physical, and mental fatigue.

  • General fatigue is associated with unsaturated fatty acid biosynthesis, indicating its role in lipid metabolism.
  • Physical fatigue was associated with plasmalogen synthesis, mitochondrial beta-oxidation of long-chain fatty acids, and selenoamino acid metabolism, suggesting a potential contribution of impaired energy production.
  • Mental fatigue is associated with homocysteine degradation and catecholamine biosynthesis, which may influence cognitive fatigue.

This exploratory study suggests that fatigue in patients with NCDs may involve disruptions in lipid metabolism, neurotransmitter pathways, microbial composition, and genetic variations. Blood-based biomarkers showed better predictive potential for physical fatigue, whereas salivary-based models were more indicative of mental fatigue.

Although our findings support the role of lipid metabolism, the contribution of plasmalogen synthesis remains underexplored. Further studies are needed to validate these findings and understand their mechanisms of action.”

https://link.springer.com/article/10.1186/s12911-025-03034-3 “Visualizing fatigue mechanisms in non-communicable diseases: an integrative approach with multi-omics and machine learning”

A human study of metabolic dysfunction-associated steatotic liver disease (MASLD) included investigating plasmalogens:

“In this study, we applied untargeted metabolomic profiling to serum samples from individuals with and without MASLD, classified by the Fatty Liver Index, with the goal of identifying characteristic metabolic signatures and pathways that may underlie disease presence and progression. Individuals in the MASLD group displayed significantly higher levels of ALT, AST, ALP, and GGT, reflecting ongoing hepatic injury, cholestasis, and oxidative stress. However, albumin and bilirubin levels remained within normal limits, indicating early to intermediate disease stages rather than advanced fibrosis or cirrhosis.

A consistent and highly significant lipidomic pattern in the MASLD group is the depletion of plasmalogens and sphingomyelins. Depletion of these lipid classes was identified as a hallmark of insulin resistance as defined by the triglyceride-glucose index. In contrast, phosphatidylcholine, phosphatidylethanolamine, and phosphatidylinositol species were elevated in MASLD, pointing toward broader lipid remodeling events.

Reduced plasmalogen and sphingomyelin levels positions their depletion as a core feature of metabolic dysfunction. Plasmalogens are ether phospholipids with strong antioxidant capacity, and their reduction suggests a loss of protective buffering against oxidative stress, one of the main drivers of MASLD progression. Similarly, sphingomyelin depletion implicates altered membrane dynamics and signaling disturbances, further contributing to metabolic dysfunction.

Depletion of plasmalogens 1-(1-enyl-palmitoyl)-2-oleoyl-GPC (P-16:0/18:1), 1-(1-enyl-palmitoyl)-2-linoleoyl-GPC (P-16:0/18:2), 1-(1-enyl-palmitoyl)-2-palmitoyl-GPC (P-16:0/16:0), 1-(1-enyl-palmitoyl)-2-palmitoleoyl-GPC (P-16:0/16:1), 1-(1-enyl-palmitoyl)-2-oleoyl-GPE (P-16:0/18:1), 1-(1-enyl-palmitoyl)-2-linoleoyl-GPE (P-16:0/18:2), and disruption of the glutamate–gamma-glutamyl pathway stand out as central features of metabolic dysfunction in MASLD, with clear potential to inform biomarker discovery, disease classification, and the design of targeted therapeutic strategies.”

https://www.mdpi.com/2218-1989/15/11/687 “Metabolomic Signatures of MASLD Identified by the Fatty Liver Index Reveal Gamma-Glutamyl Cycle Disruption and Lipid Remodeling”

A rodent study investigated dietary sea squirt (AM) plasmalogen ethanolamine (PlsEtn) extract’s and dietary pig liver (PL) phosphatidyl ethanolamine (PtdEtn) extract’s effects on acetaminophen liver injury:

“We investigated dietary effects of PlsEtn from ascidian on chronic hepatic injury in acetaminophen (APAP)-treated mice. Five-week-old male mice were divided into four groups (n = 12), which were treated with experimental diets for two weeks and then the respective APAP-containing diet for five weeks.

Ingested PlsEtn is digested into lysoPlsEtn and free fatty acid in the small intestine. PlsEtn digests are absorbed and are subsequently resynthesized into PlsEtn preferentially with PUFA.

Acetaminophen is a frequently used analgesic and antipyretic. Approximately 90% of APAP is metabolized by UDP-glucuronosyltransferase and sulfotransferase into glucuronic acid and sulfate conjugates, respectively.

5–9% of APAP is metabolized into the highly reactive intermediate N-acetyl-p-benzoquinone imine (NAPQI). This metabolite is considered a pivotal molecule in APAP-induced hepatotoxicity and is conjugated by glutathione (GSH). Excessive NAPQI levels deplete GSH and covalently bind to cellular proteins, resulting in organelle dysfunction, such as mitochondria dysfunction. These impairments induce oxidative stress, cell malfunctions, and subsequently, cell death, such as ferroptosis and apoptosis.

Mice were treated with continuous APAP consumption to induce oxidative stress and impaired lipid metabolism in the liver. Effects of diets were evaluated based on levels of malondialdehyde (MDA), a marker of lipid oxidation, on fatty acid content, and on expression of apoptosis-related proteins in the liver.

The PlsEtn-rich diet effectively suppressed APAP-induced decrease in body and liver weights of mice. However, this suppressive effect was not observed in mice fed a PtdEtn-rich diet. APAP administration decreased the total fatty acid content in the liver, whereas a PlsEtn-rich diet alleviated this decrease and increased the hepatic content of docosahexaenoic acid (DHA).

Owing to the alkenyl linkage, which exhibits antioxidant properties, PlsEtn was expected to markedly suppress hepatic lipid oxidation. However, its suppressive effect was the same extent as that by PtdEtn. Both PlsEtn and PtdEtn contain an ethanolamine base in their structures, and free ethanolamine and its metabolite choline suppress lipid peroxidation. Dietary PlsEtn and PtdEtn may be metabolized into free ethanolamine and its further metabolites, which may alleviate APAP-induced hepatic lipid oxidation.

Dietary ethanolamine glycerophospholipids (EtnGpls) rich in PlsEtn or PtdEtn suppressed APAP-induced lipid oxidation in the liver. Protein expression results revealed that dietary EtnGpls reduced expression of certain apoptosis-related proteins compared to the APAP group. This reduction was more effective in mice fed the PlsEtn-rich diet than in those on the PtdEtn-rich diet.”

https://www.mdpi.com/2076-3417/15/11/5968 “Dietary Ethanolamine Plasmalogen from Ascidian Alleviates Chronic Hepatic Injury in Mice Treated with Continuous Acetaminophen”

This study neither demonstrated nor provided citations for its dietary plasmalogen recycling statements.

Three more plasmalogen health and disease papers are curated in Part 2.

Combining exercise with sulforaphane

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A 2025 clinical trial with old people compared NRF2 effects of acute exercise with pre- and post-exercise sulforaphane treatment:

“This study tested the hypothesis that combining acute exercise (in vivo stimulus) with ex vivo sulforaphane (SFN) treatment would induce greater NRF2 activation and signaling in older adults compared to either treatment alone. This approach was used to bypass the potential issue of inter-individual variability in metabolism and bioavailability of SFN supplementation through oral consumption and thereby provide more rigorous biological control to establish mechanistic feasibility.

Twenty-five older adults (12 men, 13 women; mean age: 67 ± 5 years) performed 30-min cycling exercise. Blood was drawn before and immediately after exercise to isolate peripheral blood mononuclear cells (PBMCs) and incubate with and without SFN (5 μM) treatment.

Acute exercise induced modest transcriptional changes across the four tested transcripts compared to the robust upregulation elicited by SFN. This disparity was notable given the comparable NRF2/ARE binding activity observed between EX and SFN.

Near-significant trends were observed for EX in heme oxygenase-1 (HO-1), NAD(P)H quinone oxidoreductase 1 (NQO1), and glutathione reductase (GR) (after Bonferroni correction), while glutamate-cysteine ligase catalytic subunit (GCLC) was not induced by EX. In contrast, SFN alone robustly induced expression of NQO1, HO-1, GR, and GCLC.

We had chosen 5 μM as the dose based on pilot data from our laboratory and existing literature from in vitro experiments. However, typically, SFN is not combined with another stimulus.

To test this speculation, we ran a post hoc dose–response experiment where we stimulated PBMCs (n = 5) at six different SFN concentrations ranging from 0 to 20 μM (incubated for 5 h) and analyzed responses across the four genes used in the present study. The dose responses displayed hormetic curves for NQO1, GR, and GCLC, with 5 μM eliciting the peak response, suggesting that the lack of difference between SFN and the combined treatment was due to a ceiling effect of the SFN dose. Interestingly, HO-1 displayed a linear/curvilinear response with the maximal observed response at 20 μM.

In future ex vivo studies, a sulforaphane concentration of 1–2 μM in combination with acute exercise is predicted to enhance the expression of these antioxidant genes in the PBMCs of older adults to a greater extent than either treatment alone. Furthermore, lower SFN plasma concentrations are more likely to be achievable with oral supplementation.

To our knowledge, this is the first trial to measure responses to acute exercise combined with sulforaphane stimulation on NRF2 signaling in older men and women. We did not observe any statistically significant differences in any of our outcome variables between men and women.

Our results demonstrate that combining acute exercise with a sulforaphane stimulus elicits a greater response in nuclear NRF2 activity in older adults. While the response in gene expression did not completely mirror the response in NRF2 activation, it is important to note that NRF2 induces hundreds of cytoprotective genes. The four transcripts we measured are among those most commonly used to represent NRF2 signaling but do not capture the full picture. Full transcriptomics in future studies would address this question.”

https://link.springer.com/article/10.1007/s11357-025-01939-5 “Sulforaphane improves exercise-induced NRF2 signaling in older adults: an in vivo-ex vivo approach” (not freely available) Thanks to Dr. Tinna Traustadóttir for providing a copy.

I asked two questions, and will follow up with replies:

  1. Did a second experiment test effects of these subjects eating broccoli sprouts prior to acute exercise? The clinical trial’s NCT04848792 Study Overview section indicated that was the researchers’ intent.
  2. What studies have the data that produced this study’s graphical abstract’s younger vs. older NRF2 response graph?

Sulforaphane and malaria

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A 2025 rodent study investigated sulforaphane’s capability as an adjunct with standard treatment to inhibit resistant malaria strains:

“In this study, we performed proteomic analysis on a range of sensitive and artemisinin-resistant parasites, revealing specific dysregulation of PfK13 protein abundance. Reduced PfK13 levels were linked to impaired hemoglobin digestion, decreased free heme levels, and consequently, decreased artemisinin activation. Artemisinin resistant parasites also exhibited elevated thiol levels, indicating a more reduced cellular state.

Modulation of PfK13 levels or localisation modifies glutathione (GSH) levels, and elevated GSH decreases artemisinin potency. Elevated levels of reduced GSH and its precursor γ-glutamyl cysteine (gGlu-Cys) were observed in resistant parasites, while oxidised glutathione (GSSG) was lower.

In mammalian cells, SFN conjugates GSH, either passively or through the activity of glutathione-S-transferases, and the SFN-GSH conjugate causes oxidative stress. In response to this stress, Nrf2 translocates to the nucleus and interacts with the antioxidant response element (ARE) of target genes, resulting in expression of antioxidant genes, which induces an antioxidant response. However, P. falciparum has no identified Nrf2 orthologue and so likely lacks a KEAP1-Nrf2 mediated antioxidant response, which suggests that the SFN-GSH conjugate should only cause oxidative stress in parasites.

SFN has antioxidant properties for the host through activation of Nrf2. Therefore our molecule of choice would not only kill the parasite, but will boost the host antioxidant capacity. This differs from most other available pro-oxidants, which do not have this host antioxidant capacity.

5mg/kg SFN was found to be sufficient to significantly prolong the survival of artesunate-treated mice infected with parasites.

PfK13 mutations drive artemisinin resistance in Plasmodium parasites by enhancing antioxidant defences, which can be targeted by redox modulators such as sulforaphane. By leveraging SFN’s ability to induce oxidative stress and deplete thiol levels in parasites, this approach can enhance the efficacy of artemisinin and potentially restore its effectiveness against resistant strains.”

https://www.biorxiv.org/content/10.1101/2025.10.05.680568v1.full “PfK13-associated artemisinin resistance slows drug activation and enhances antioxidant defence, which can be overcome with sulforaphane”

Practice what you preach, or shut up

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A 2025 review subject was sulforaphane and brain health. This paper was the latest in a sequence where the retired lead author self-aggrandized his career by citing previous research.

He apparently doesn’t personally do what these research findings suggest people do. The lead author is a few weeks older than I am, and has completely white hair per an interview (Week 34 comments). I’ve had dark hair growing in (last week a barber said my dark hair was 90%) since Week 8 of eating broccoli sprouts every day, which is a side effect of ameliorating system-wide inflammation and oxidative stress.

If the lead author followed up with what his research investigated, he’d have dark hair, too. Unpigmented white hair and colored hair are both results of epigenetics.

Contrast this lack of personal follow-through of research findings with Dr. Goodenowe’s protocol where he compared extremely detailed personal brain measurements at 17 months and again at 31 months. He believes enough in his research findings to personally act on them, and demonstrate to others how personal agency can enhance a person’s life.

It’s every human’s choice whether or not we take responsibility for our own one precious life. I’ve read and curated on this blog many of this paper’s references. Five years ago for example:

So do more with their information than just read.

https://www.mdpi.com/2072-6643/17/8/1353 “Sulforaphane and Brain Health: From Pathways of Action to Effects on Specific Disorders”

2025 α-ketoglutarate research

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I haven’t mentioned α-ketoglutarate for a while, although I’ve taken it twice a day for several years. Here are four 2025 papers on α-ketoglutarate, starting with a review of its role in bone health:

“α-Ketoglutarate (α-KG) serves as a pivotal intermediate in various metabolic pathways in mammals, significantly contributing to cellular energy metabolism, amino acid metabolism, and other physiological processes. α-KG may be a therapeutic target for a variety of bone-related diseases, such as osteoporosis, osteoarthritis, and rheumatoid arthritis, because of its role in maintaining metabolic balance of bone.

α-KG, as a rate-determining mitochondrial intermediate, is crucial in cell energy metabolism because it connects intracellular carbon and nitrogen metabolism between isocitrate and succinyl coenzyme A. Additionally, α-KG is closely involved in the amino acid cycle. As a precursor of amino acids such as glutamine and glutamic acid, α-KG plays a direct role in energy production and a wide range of cellular chemical reactions. α-KG provides an energy source, stimulating protein synthesis, inhibiting protein degradation in muscle, and serving as a significant metabolic fuel for gastrointestinal cells.

α-KG promotes osteogenic differentiation of stem cells, increases activity of osteoblasts to promote osteogenesis, and inhibits bone resorption activity of osteoclasts. α-KG in articular cartilage promotes differentiation and maturation of chondrocytes and formation of a cartilage matrix. The protective effect of α-KG on bone has practical value in treatment of abnormal bone loss symptoms in various bone tissue diseases.”

https://www.sciengine.com/ABBS/doi/10.3724/abbs.2025020 “Essential role of the metabolite α-ketoglutarate in bone tissue and bone-related diseases”

A rodent study explored adding α-KG to osteoarthritis treatment:

“Mesenchymal stem cell (MSC) therapy represents a promising treatment strategy for osteoarthritis (OA). Nevertheless, the therapeutic efficacy of MSCs may be attenuated under conditions of cellular senescence or when the available clinical quantity is insufficient. α-Ketoglutarate (AKG) exerts beneficial effects on skeletal tissues and activity of stem cells. The present study was designed to explore the potential of AKG in augmenting viability of MSCs and the potential of their combined utilization in treatment of OA.

AKG plays a crucial role in multiple biological processes. It is involved in regulating stem cell differentiation, exerts anti-apoptotic effects, modulates the body’s immune and inflammatory responses, contributes to muscle and bone development, and is essential for maintaining stability of the cartilage matrix.

Platelet-rich plasma (PRP) has been demonstrated to have protective effects on chondrocytes and can effectively repair damaged cartilage in OA. However, PRP has intractable problems in terms of product quality control and allogeneic application, and its long-term therapeutic effect gradually weakens.

Combining AKG’s regulation of cellular metabolism with the multi-directional differentiation and immunomodulatory functions of MSCs is likely to generate a synergistic effect. This combined treatment modality targets the complex pathological processes of OA, including cartilage damage, inflammatory responses, and extracellular matrix imbalance, in a more comprehensive manner than a single therapy.”

https://www.sciencedirect.com/science/article/pii/S2707368825000032 “The repair effect of α-ketoglutarate combined with mesenchymal stem cells on osteoarthritis via the hedgehog protein pathway”

A rodent study investigated whether α-KG has a role in determining frailty:

“Frailty is an age-related geriatric syndrome, for which the mechanisms remain largely unknown. We performed a longitudinal study of aging female (n = 40) and male (n = 47) C57BL/6NIA mice, measured frailty index, and derived metabolomics data from plasma samples.

We find that frailty related metabolites are enriched for amino acid metabolism and metabolism of cofactors and vitamins, include ergothioneine, tryptophan, and alpha-ketoglutarate, and present sex dimorphism. We identify B vitamin metabolism related flavin adenine dinucleotide and pyridoxate as female-specific frailty biomarkers, and lipid metabolism related sphingomyelins, glycerophosphoethanolamine and glycerophosphocholine as male-specific frailty biomarkers.

We were interested to observe whether metabolite abundance at any specific timepoint was associated with frailty at a future timepoint. Unfortunately, we didn’t observe any metabolites that showed an overall significant association with future FI (FIf) or future devFI (devFIf). When focusing only on the abundance of metabolites at the baseline time point (∼400 days), we found a single metabolite, alpha-ketoglutarate, was negatively associated with both FIf and devFIf.”

https://www.biorxiv.org/content/10.1101/2025.01.22.634160v1.full “Metabolomics biomarkers of frailty: a longitudinal study of aging female and male mice”

Wrapping up with a rodent study adding α-KG to exercise for its effects on depression and learning:

“aKG acts as a prophylactic and antidepressant to effectively counteract social avoidance behaviors by modulating BDNF levels in the hippocampus and nucleus accumbens. Exercise increases aKG levels in the circulation.

In mice, aKG supplementation prolongs lifespan and reduces aging-associated frailty. aKG supplementation also reverses aging in humans as measured by DNA methylation patterns.

aKG functions as a co-factor for epigenetic enzymes. Changes in the intracellular αKG/succinate ratio regulates chromatin modifications, including H3K27me3 and ten-eleven translocation (Tet)-dependent DNA demethylation. The ability of aKG to influence epigenetic status of cells may explain both its prophylactic and anti-depressant effects since transcriptional dysregulation and aberrant epigenetic regulation are unifying themes in psychiatric disorders. This may also explain its ability to differentially regulate BDNF expression in the hippocampus and NAc.

If exercise mediates its effects through aKG, aKG may be a pivotal component of an exercise pill along with lactate and BHB that can serve as both a prophylactic and antidepressant treatment for depression.”

https://www.sciencedirect.com/science/article/pii/S266717432500031X “α-ketoglutarate (aKG) is a circulatory exercise factor that promotes learning and memory recall and has antidepressant properties

Nrf2 regulation

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This 2025 review explored what’s known so far about Nrf2 post-translational regulators:

“Nrf2 is controlled at multiple levels, including epigenetic, transcriptional, translational, and post-translational. The focus of this review is on proteins that control Nrf2 at the post-translational level because in normal cells they are of preeminent importance.

We outline mechanisms by which multiple E3 ubiquitin ligases act to repress Nrf2 expression, how derepression of Nrf2 (and induction of its target genes) by oxidative stressors occurs, and why tissue injury and endoplasmic reticulum stress downregulate Nrf2. This update also explains how Nrf2 is embedded in thiol biochemistry, and outlines signaling pathways and endogenous signaling molecules that control its activity.

Nrf2 not only positively controls the basal and/or inducible expression of a substantial number of genes in all tissues but also downregulates many genes. Estimates of the number of antioxidant/electrophile-responsive element (ARE/EpRE)-driven genes that are positively regulated by Nrf2 vary from several hundred to >2000 depending on the experimental method, species, cell type, physiology, age, sex, diet, and the magnitude of the change that is deemed to be significant.

Induction of ARE/EpRE-driven genes allows adaptation to oxidative, electrophilic, and inflammatory stress. Nrf2 positively regulates clusters of genes encoding proteins classed broadly as antioxidant, drug-, heme-, and iron-metabolizing, pentose phosphate pathway, NADPH-generating, and autophagy-related, as well as fatty acid oxidation enzymes, lipases, transcription factors, and Keap1.

Genes that are negatively regulated by Nrf2 include those encoding the cytokines IL-1β and IL-6, myosin light-chain kinase (MYLK), and NADPH oxidase 4 (NOX4). Nrf2 also regulates some microRNAs, which represents another mechanism by which Nrf2 can downregulate the expression of genes such as those encoding collagens 1A2, 3A1, and 5A1, heat shock protein 47, fibronectin, and elastin. In addition, several lipogenesis-related genes such as fatty acid synthase 1 (FASN1) and acetyl-CoA carboxylase 1 (ACC1), stearoyl-CoA desaturase (SCD1), and fatty acid elongase 6 (ELOVL6) are downregulated upon Nrf2 activation, particularly under conditions of lipid overload. Given that lipogenesis is a highly NADPH-consuming process, it seems that Nrf2 activation redirects NADPH consumption from lipid synthesis towards redox reactions, although the mechanisms underlying the negative regulation of these genes are incompletely understood.

de novo synthesized Nrf2 upon Keap1 inactivation enables a rapid increase of levels of the transcription factor in response to metabolic changes and environmental challenges, allowing cells to adapt and restore homeostasis.”

https://www.cell.com/trends/biochemical-sciences/fulltext/S0968-0004(24)00282-2 “Regulating Nrf2 activity: ubiquitin ligases and signaling molecules in redox homeostasis”

This review’s primary audience is other researchers, and it ended with 15 outstanding items that Nrf2 research hasn’t yet adequately addressed.

Polyphenol Nrf2 activators

gettingwell4 2-3 stars Required further work, Acetylcholine, Amygdala, Cerebrum, Cortisol, Dopamine, Epigenetics, Glutamate, Hippocampus, Hypothalamus, Immune system, Limbic system, Memory, Neurochemicals, Oxytocin, Serotonin, Stress, Vasopressin , , , , ,

Two 2024 reviews by the same group that published Sulforaphane in the Goldilocks zone investigated dietary polyphenols’ effects as “hormetic nutrients”:

“Polyphenols display biphasic dose–response effects by activating at a low dose the Nrf2 pathway resulting in the upregulation of antioxidant vitagenes [see diagram]. We aimed to discuss hormetic nutrients, including polyphenols and/or probiotics, targeting the Nrf2 pathway and vitagenes for the development of promising neuroprotective and therapeutic strategies to suppress oxidative stress, inflammation and microbiota deregulation, and consequently improve cognitive performance and brain health.

antioxidants-13-00484-g001

Hormetic nutrition through polyphenols and/or probiotics targeting the antioxidant Nrf2 pathway and stress resilient vitagenes to inhibit oxidative stress and inflammatory pathways, as well as ferroptosis, could represent an effective therapy to manipulate alterations in the gut microbiome leading to brain dysfunction in order to prevent or slow the onset of major cognitive disorders. Notably, hormetic nutrients can stimulate the vagus nerve as a means of directly modulating microbiota-brain interactions for therapeutic purposes to mitigate or reverse the pathophysiological process, restoring gut and brain homeostasis, as reported by extensive preclinical and clinical studies.”

https://www.mdpi.com/2076-3921/13/4/484 “Hormetic Nutrition and Redox Regulation in Gut–Brain Axis Disorders”

I’m not onboard with this study’s probiotic assertions because most of the cited studies contained unacknowledged measurement errors. Measuring gut microbiota, Part 2 found:

“The fecal microbiome does not represent the overall composition of the gut microbiome. Despite significant roles of gut microbiome in various phenotypes and diseases of its host, causative microbes for such characteristics identified by one research fail to be reproduced in others.

Since fecal microbiome is a result of the gut microbiome rather than the representative microbiome of the GI tract of the host, there is a limitation in identifying causative intestinal microbes related to these phenotypes and diseases by studying fecal microbiome.”

These researchers also erroneously equated isothiocyanate sulforaphane’s Nrf2-activating mechanisms with polyphenols activating Nrf2.

This research group did better in clarifying polyphenols’ mechanisms in a review of hormetic dose-response effects of the polyphenol rosmarinic acid:

“This article evaluates whether rosmarinic acid may act as a hormetic agent, mediating its chemoprotective effects as has been shown for similar agents, such as caffeic acid, a derivative of rosmarinic acid.

Rosmarinic acid enhanced memory in institute of cancer research male mice in the Morris water maze (escape latency).

untitled

Of importance in the evaluation of rosmarinic acid are its bioavailability, metabolism, and tissue distribution (including the capacity to affect and/or cross the BBB and its distribution and half-life within the brain). In the case of polyphenols, including rosmarinic acid, they are typically delivered at low doses in the diet and, in most instances, they do not escape first-pass metabolism, with the prominent chemical forms being conjugates of glucuronides and sulfates, with or without methylation.

These conjugated metabolites are chemically distinct from the parent compound, showing considerable differences in size, polarity, and ionic form. Their biological actions are quite different from the parent compound.

Bioavailability studies reveal that maximum concentrations in plasma typically do not exceed 1 µM following consumption of 10–100 mg of a single phenolic compound, with the maximum concentration occurring typically less than 2 h after ingestion, then dropping quickly thereafter. In the case of the in vitro studies assessed herein, and with few exceptions, most of the studies employed concentrations >10 µM with some studies involving concentrations in the several hundred µM range, with the duration of exposure typically in the range of 24–72 h, far longer duration than the very short time interval of a few minutes to several hours in human in vivo situations.

We strongly recommend that all experiments using in vitro models to study biological responses to dietary polyphenols use only physiologically relevant flavonoids and their conjugates at appropriate concentrations, provide evidence to support their use, and justify any conclusions generated. When authors fail to do this, referees and editors must act to ensure that data obtained in vitro are relevant to what might occur in vivo.”

https://www.degruyter.com/document/doi/10.1515/med-2024-1065/html “The chemoprotective hormetic effects of rosmarinic acid”

An elevator pitch for plasmalogen precursors

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An excerpt from the latest video at Dr. Goodenowe’s Health Matters podcast, Episode 7 “The Truth about Parkinson’s”, starting at 50:30:

“What’s exciting about this community medicine focus that we’ve switched to which basically says: How do we develop technologies in a way that they can be incorporated into a community model versus a pharmaceutical drug model? People can actually do I would say self-experiment just the way you self-experiment with your own diet because these are fundamentally dietary nutrition molecules.

Could you give me an elevator pitch because there are probably people listening who are thinking what is this plasmalogen precursor and for sure how is it having this dramatic effect?

Plasmalogens are the most important nutrient that nobody knows about. Normally you don’t know about it because the body is usually pretty good at making them. What makes plasmalogens unique is that your body makes them kind of like cannon fodder, the first group of people that go into war. Your body throws them out for destruction. They absorb oxidative stress and get destroyed in the process.

They’re stored in your cell membranes. 50% of the membranes of your heart are these plasmalogen molecules. When your heart gets inflamed, what your heart does is it dumps these plasmalogens out of its membranes to douse the flame of inflammation. After inflammation is under control, your body naturally builds these things back up again.

But if you have an inability to make enough plasmalogens, these inflammation events knock you down and keep you down. So plasmalogen precursors are critical for maintaining high levels of plasmalogens across your body, not just in your brain (30% of the lipids in your brain) but in your heart, your lungs, your kidneys.”

PXL_20241117_185248742~2

Activate Nrf2 to reduce biological age

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A 2024 primate study investigated effects of an off-patent drug on age-related changes:

“We evaluated geroprotective effects of metformin on adult male cynomolgus monkeys. The study encompassed a comprehensive suite of physiological, imaging, histological, and molecular evaluations, substantiating metformin’s influence on delaying age-related phenotypes at the organismal level.

monkey nrf2

Results highlighted a significant slowing of aging indicators, notably a roughly 6-year regression in brain aging. Metformin exerts a substantial neuroprotective effect, preserving brain structure and enhancing cognitive ability.

Geroprotective effects on primate neurons were partially mediated by activation of Nrf2, a transcription factor with anti-oxidative capabilities.”

https://www.cell.com/cell/abstract/S0092-8674(24)00914-0 “Metformin decelerates aging clock in male monkeys” (not freely available). Thanks to Dr. Pradeep Reddy for providing a copy.

From this study’s Nrf2 activation findings:

“Metformin treatment resulted in increased nuclear phosphorylated Nrf2, accompanied by up-regulation of Nrf2 target genes like HO-1, NQO-1, SOD3, GPX2, and GPX1, which were generally suppressed and typically down-regulated during human neuron senescence.

Genes pivotal for neuronal function, such as dendrite morphogenesis/extension and synapse assembly (e.g., GSK3B, GRID2, and NRG3), were down-regulated during aging in excitatory neurons (ExN), inhibitory neurons (InN), oligodendrocytes (OL), oligodendrocyte progenitor cells (OPC), microglia, and astrocyte but were restored by metformin treatment. By contrast, pathways that were up-regulated during aging, including activation of the immune response, complement activation, and regulation of the TGF-b receptor signaling pathway, were reset to lower levels by metformin treatment.

metformin neuronal gene pathways

We verified that markers associated with brain aging and progression of neurodegenerative diseases were restored by metformin treatment to levels similar to those observed in young monkeys. Additionally, we observed that reduced myelin sheath thickness, a characteristic of aged monkeys, was rebuilt to a younger state following metformin treatment.

These findings align with the levels of nuclear-localized phosphorylated Nrf2, suggesting that Nrf2 pathway activation is a key mechanism in metformin’s role in delaying human neuronal aging and, by extension, brain aging. Consistent with our in vitro findings, Nrf2 pathway activation was also detected across multiple tissues in metformin-treated monkeys, including frontal lobe neurons.

At last count, I’ve curated 250+ papers this decade on cruciferous vegetables, and many of these explored relationships with Nrf2 activation. Basically, eating a clinically-relevant daily dose of 3-day-old cruciferous sprouts and taking off-patent metformin both induce Nrf2 activation effects.

Don’t expect to see many researchers highlighting this equivalency. They’d rather wait another decade to nitpick other studies with not-enough-subjects / not-exactly replicated / other nitpicks before expressing opinions urging caution from their nursing home beds.

But even then, they won’t get their facts straight. For example, a contemporaneous opinion article https://www.nature.com/articles/d41586-024-02938-w “The brain aged more slowly in monkeys given a cheap diabetes drug” attempted to summarize this study, and flubbed two points:

1. The study said: “We conducted a proof-of-concept study involving male cynomolgus monkeys (Macaca fascicularis) aged between 13 and 16 years, roughly equivalent to approximately 40–50 years in humans. Monkeys adhered to this regimen for a period of 1,200 days, approximately 3.3 years, which corresponds to about 10 years in humans.”

The opinion claimed: “Animals took the drug for 40 months, which is equivalent to about 13 years for humans.”

2. The opinion quoted a New York City researcher involved in a separate metformin study and employed at a medical school for:

“Research into metformin and other anti-ageing candidates could one day mean that doctors will be able to focus more on keeping people healthy for as long as possible rather than on treating diseases.”

This statement is a big break from the realities of medical personnel daily actions at least so far this decade, which is when I started to pay close attention:

  • Doctors have very little diet and exercise training in medical school. There’s no way they can give health advice. There’s no way that a “keeping people healthy” paradigm will emerge from the current medical system.
  • Fixing a disease doesn’t restore a patient’s health. Dr. (PhD) Goodenowe cites several examples in his talks, such as a study that compared colorectal cancer therapy with post-operation patient health.
  • If you listen to yesterday’s two-hour-long podcast, the currently injured person in the first hour gave plenty of contrary evidence of doctors’ focuses: behaviors of trying to blame and gaslight the patient, thinly-disguised punitive actions, CYA etc., all of which they will be sued for one day. The doctor in the second hour provided an example of the quoted researcher in her explanation of how doctors higher in the hierarchy either can’t see or can’t admit realities of doctor/patient interactions, and what therapies have actually benefited or harmed a patient.

Consequences of perinatal stress

gettingwell4 4-5 stars Advanced knowledge, Amygdala, Brain development, Cerebrum, Dopamine, Epigenetics, Glutamate, Hippocampus, Limbic system, Memory, Neurochemicals, Stress, Thalamus , , , , , ,

A 2024 rodent study followed up earlier studies of perinatal stress:

“Stress is a multisystemic and multiscale reaction experienced by living beings in response to a wide range of stimuli, encompassing a highly complex order of biological and behavioral responses in mammals, including humans. In the present study, we evaluated changes in mRNA levels in 88 regions of interest (ROIs) in male rats both exposed to perinatal stress and not exposed.

Depending on critical life stage (e.g., perinatal life, infancy, childhood, adolescence, aging), duration, and type of stressor, different effects can be detected by examining behavioral and physiological functions. Stress is related to several cognitive processes, including spatial and declarative memory (involving the hippocampus), fear and memories of emotionally charged events (involving the amygdala), and executive functions and fear extinction (involving the prefrontal cortex).

This PRS paradigm is a well-characterized animal model in which offspring is exposed to stress during pregnancy and after birth because of receiving defective maternal care. Offspring exhibit behavioral hyperreactivity, as well as increased susceptibility to drug addiction and decreased risk-taking behavior.

Starting from day 11 of gestation until delivery, pregnant females were subjected to restraint in a transparent plastic cylinder and exposed to bright light during three daily sessions of 45 min. Since gestational stress induces a <40% reduction of maternal behavior in stressed mothers, we refer to the whole procedure as Perinatal Stress.

Intercorrelation between the orbitofrontal cortex (OFC) and various brain regions such as the thalamus and amygdala were found disrupted in the PRS group. These functional correlations appear to be associated with regulation of executive functions, goal-directed behavior, and directed attention. Also, discrete functional links between the OFC and limbic regions and striatum were lost in the PRS group.

Decreased expression of the Homer1a gene across multiple brain regions after perinatal stress exposure may derange normal architecture of glutamatergic synapses during neurodevelopment and after birth. Changes at the glutamatergic synapse have been considered pivotal in adaptive stress behaviors.

Our results show that PRS preferentially reinforces the centrality of subcortical nodes, resulting in increased centrality of structures such as amygdala, caudate-putamen, and nucleus accumbens, suggestive of reduced cortical control over these regions. In conclusion, when analyzing Homer gene expression after stress exposure not only in terms of quantitative changes compared to the control group, but also as a basis for conducting brain connectivity graph analysis, we observed that perinatal stress could significantly affect the functional connectivity of brain regions implicated in modeling pathophysiology of severe psychiatric disorders.”

https://www.sciencedirect.com/science/article/pii/S0278584624001003 “Perinatal stress modulates glutamatergic functional connectivity: A post-synaptic density immediate early gene-based network analysis”

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Maintaining your myelin, Part 2

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Continuing Part 1 with three 2024 preprint studies, starting with an investigation of neuroinflammation in high school athletes:

“Axons are long fibers conducting nerve impulses from nerve cells to synaptic ends. Like electric wires, axons are insulated by the myelin sheath produced by oligodendrocytes (ODC) in the brain or Schwann cells in the periphery. The myelin sheath is vulnerable to mechanical stresses after head injuries, as well as targets for autoimmune attack in multiple sclerosis and degeneration in various white matter diseases.

145850ce6289d06e5318d35f

It is challenging to definitively validate axonal neuroinflammation, because axonal neuroinflammation is only diagnosed at post-mortem autopsy, or wait for more than a decade to potentially witness progression to chronic traumatic encephalopathy, or white matter dementia. Advanced imaging analysis of computed tomography and magnetic resonance imaging are not sensitive enough to identify such microscopic abnormalities.

We developed a sandwich immunoassay detecting dual signals of myelin oligodendrocyte glycoprotein (MOG) and interleukin 1B (IL1B) in human plasma, [IL1B on MOG]. MOG is a transmembrane protein specifically expressed in ODC and Schwann cells membranes, and doesn’t freely exist in plasma. We found that serum from capillary blood is acceptable, and we tested control and athlete samples using only 5 mL samples. When we tested 63 control plasma samples, values were widely distributed over 2 logs, so we focused on longitudinal studies.

Damaged neurons are not easily detectable using conventional physical examinations, because the brain’s inherent adaptability allows it to compensate for localized damage by finding alternate routes. While this adaptability is advantageous, it also means that these concealed lesions can go unnoticed, potentially leading to future complications.

Elevation of [IL1B on MOG] was seen in some athletes who did not show concussion or traumatic brain injury (TBI). While the occurrence of concussion is relatively limited, potential prevalence of subconcussion or subconcussive condition is expected to be substantially higher.

If [IL1B on MOG] levels remain unchanged during this early post-concussion period (2-4 weeks), it may suggest that neuroinflammation has not been induced, potentially providing reassurance for the athletes to return to play. Conversely, if [IL1B on MOG] levels increase within this timeframe, it may indicate the need for intervention or closer monitoring. Thus, there is compelling potential for incorporating this test into concussion guidelines.”

https://www.researchsquare.com/article/rs-3997676/v1 “An approach for the analysis of axonal neuroinflammation by measuring dual biomarkers of oligodendrocytes and inflammatory cytokine in human plasma”

A rodent study investigated the immune system’s influence on oligodendrocyte lineage cells after TBI:

“White matter injury is thought to be a major contributor to long-term cognitive dysfunctions after TBI. This damage occurs partly due to apoptotic death of oligodendrocyte lineage cells (OLCs) after injury, triggered directly by the trauma or in response to degenerating axons.

Our data indicates that depletion of the gut microbiota after TBI impaired remyelination, reduced OLCs proliferation, and required the presence of T cells. This suggests that T cells are an important mechanistic link by which the gut microbiota modulate oligodendrocyte response and white matter recovery after TBI.

Our findings suggest that oligodendrocytes are not passive in the neuroinflammatory and degenerative environment caused by brain trauma, but instead could exert an active role in modulation of immune response.”

https://www.researchsquare.com/article/rs-4289147/v1 “Gut Microbiota Shape Oligodendrocyte Response after Traumatic Brain Injury”

A rodent study investigated whether oligodendrocyte precursor cells had myelination-independent roles in brain aging:

“OPCs, the source cells of myelin-forming cells in the central nervous system, have been linked to brain aging by their compromised differentiation and regeneration capability. Our results demonstrate that macroautophagy influx declines in aged OPCs, which results in the accumulation of senescent OPCs in aged brains. Senescent OPCs impair neuronal plasticity and exacerbate neurodegeneration, eventually leading to cognitive decline.

Inactivation of autophagy in OPCs exhibits a limited effect on myelin thickness but a loss of myelin in middle-aged mice. The loss of myelin observed is an adaptational change to suppressed neuronal plasticity. However, neither the number of OLs nor oligodendrogenesis is altered by inactivation of autophagy in adult OPCs.

The present study indicates that the intervention of senescent OPCs is an additional promising therapeutic strategy for aging and aging-related cognitive deficits. Autophagy regulates senescence by impairing protein turnover, mitochondrial homeostasis, oxidative stress, and maintaining senescence-associated secretory phenotype. Further investigation remains on whether autophagy in OPCs shares the exact mechanism to promote senescence as that in other types of cells.

Considering autophagy declines with aging, our study brings a novel mechanism in brain aging. Declined autophagy causes senescence of OPCs, which impairs neuronal plasticity and exacerbates neurodegeneration via CCL3/5-CCR5 signaling.”

https://www.researchsquare.com/article/rs-3926942/v1 “Impaired Macroautophagy in Oligodendrocyte Precursor Cells Exacerbates Aging-related Cognitive Deficits via a Senescence Associated Signaling”

PXL_20240418_104114528.MP

Maintaining your myelin, Part 1

gettingwell4 4-5 stars Advanced knowledge, Acetylcholine, Brain development, Brainstem, Cerebellum, Cerebrum, Epigenetics, Glutamate, Hypothalamus, Immune system, Limbic system, Lower brain, Memory, Neurochemicals, Stress, Thalamus , , , , , , , , ,

Three papers on myelin and oligodendrocytes, starting with a 2023 review:

“Myelin is the spiral ensheathment of axons by a lipid and cholesterol-rich glial cell membrane that reduces capacitance and increases resistance of the axonal membrane. Axonal myelination speeds up nerve conduction velocity as a function of axon diameter.

While myelination proceeds rapidly after birth in the peripheral nervous system, central myelination is a spatially and temporally more regulated process. Ongoing myelination of the human brain has been documented at up to 40 years of age. This late myelination in the adult cortex is followed by exhaustion of oligodendrocyte precursor cells (OPC) with senescence and a gradual loss of myelin integrity in the aging brain.

The brain is well known for its high energy demands, specifically in gray matter areas. In white matter tracts, energy consumption is lower. Myelination poses a unique challenge for axonal energy generation where myelin sheaths cover more than 95% of the axonal surface areas.

Oligodendrocytes help support axonal integrity. Oligodendrocytes survive well in the absence of mitochondrial oxidative phosphorylation, and without signs of myelin loss, cell death, neurodegeneration or secondary inflammation.

Glycolysis products of oligodendroglial origin are readily metabolized in axonal mitochondria. Oligodendroglial metabolic support is critical for larger and faster-spiking myelinated axons that also have a higher density of mitochondria. An essential requirement for the direct transfer of energy-rich metabolites from oligodendrocytes to the myelinated axonal compartment is ‘myelinic channels’ within the myelin sheath.

Interactions of oligodendrocytes and myelin with the underlying axon are complex and exceed the transfer of energy-rich metabolites. Continuous turnover of myelin membranes by lipid degradation and fatty acid beta-oxidation in mitochondria and peroxisomes leads to recycling of acetate residues by fatty acid synthesis and membrane biogenesis.

1-s2.0-S0959438823001071-gr2_lrg

In human multiple sclerosis (MS) and its animal model myelin oligodendrocyte glycoprotein-experimental autoimmune encephalomyelitis (MOG-EAE), acute inflammatory demyelination is followed by axonal degeneration in lesion sites that is mechanistically not fully understood. It is widely thought that demyelination and the lack of an axon-protective myelin sheath in the presence of numerous inflammatory mediators are the main causes of axon loss.

But unprotected axons improve rather than worsen the overall clinical phenotype of EAE mice which exhibited the same degree of autoimmunity. Thus, ‘bad myelin is worse than no myelin’ because MS-relevant myelin injuries perturb the integrity of myelinic channels and metabolic support.

Dysfunctional or injured oligodendrocytes that do not allow for compensation by any other cell types turn the affected myelin ensheathment into a burden of the underlying axonal energy metabolism, which causes irreversible axon loss. Any loss of myelin integrity, as seen acutely in demyelinating disorders or more gradually in the aging brain, becomes a risk factor for irreversible neurodegeneration.”

https://www.sciencedirect.com/science/article/pii/S0959438823001071 “Expanding the function of oligodendrocytes to brain energy metabolism”

A 2024 review focused on myelin and oligodendrocyte plasticity:

“This review summarizes our current understanding of how myelin is generated, how its function is dynamically regulated, and how oligodendrocytes support the long-term integrity of myelinated axons.

Apart from its unique ultrastructure, there are several other exceptional features of myelin. One is certainly its molecular composition. Another is its extraordinary stability. This was compellingly illustrated when 5000-year-old myelin with almost intact ultrastructure was dissected from a Tyrolean Ice Man.

Myelin is a stable system in contrast to most membranes. However, myelin is compartmentalized into structurally and biochemically distinct domains. Noncompacted regions are much more dynamic and metabolically active than tightly compacted regions that lack direct access to the membrane trafficking machinery of oligodendrocytes.

The underlying molecular basis for stability of myelin is likely its lipid composition with high levels of saturated, long chain fatty acids, together with an enrichment of glycosphingolipids (∼20% molar percentage of total lipids) and cholesterol (∼40% of molar percentage of total lipids). In addition, myelin comprises a high proportion of plasmalogens (ether lipids) with saturated long-chain fatty acids. In fact, ∼20% of the fatty acids in myelin have hydrocarbon chains longer than 18 carbon atoms (∼1% in the gray matter) and only ∼6% of the fatty acids are polyunsaturated (∼20% in gray matter).

With maturation of oligodendrocytes, the plasma membrane undergoes major transformations of its structure. Whereas OPCs are covered by a dense layer of large and negatively charged self-repulsive oligosaccharides, compacted myelin of fully matured oligodendrocytes lacks most of these glycoprotein and complex glycolipids.

Schematic depiction of an oligodendrocyte that takes up blood-derived glucose and delivers glycolysis products (pyruvate/lactate) via monocarboxylate transporters (MCT1 and MCT2) to myelinated axons. Oligodendrocytes and myelin membranes are also coupled by gap junctions to astrocytes, and thus indirectly to the blood–brain barrier.

oligodendrocyte

Adaptive myelination refers to dynamic events in oligodendroglia driven by extrinsic factors such as experience or neuronal activity, which subsequently induces changes in circuit structure and function. Understanding how these adaptive changes in neuron-oligodendroglia interactions impact brain function remains a pressing question for the field.

Transient social isolation during adulthood results in chromatin and myelin changes, but does not induce consequent behavioral alterations. When mice undergo a social isolation paradigm during early life development, they similarly exhibit deficits in prefrontal cortex function and myelination, but these deficiencies do not recover with social reintroduction. This implicates a critical period for social deprivation effects on myelin dynamics. Experience-dependent changes in myelin dynamics may depend on not only the age, brain region, and cell type studied, but also the specific myelin structural change assessed.

Local synaptic neurotransmitter release along an axon not only affects the number of OPCs and oligodendrocytes associated with that axon and local synthesis of myelin proteins, but also drives preferential selection of active axons for myelination over the ensheathment of electrically silenced neighboring axons. Neuronal activity–induced plasticity may preferentially impact brain regions that remain incompletely myelinated compared to more fully myelinated tracts.

Whereas the myelin sheath has been regarded for a long time as an inert insulating structure, it has now become clear that myelin is metabolically active with cytoplasmic-rich pathways, myelinic channels, for movement of macromolecules into the periaxonal space. The myelin sheath and its subjacent axon need to be regarded as one functional unit, which are not only morphological but also metabolically coupled.”

https://cshperspectives.cshlp.org/content/early/2024/04/15/cshperspect.a041359 “Oligodendrocytes: Myelination, Plasticity, and Axonal Support” (not freely available) Thanks to Dr. Klaus-Armin Nave for providing a copy.

A 2024 rodent study investigated oligodendrocyte precursor cell transcriptional and epigenetic changes:

“We used single-cell RNA sequencing (scRNA-seq), single-cell ATAC sequencing (scATAC-seq), and single-cell spatial transcriptomics to characterize murine cortical OPCs throughout postnatal life. One group (active, or actOPCs) is metabolically active and enriched in white matter. The second (homeostatic, or hOPCs) is less active, enriched in gray matter, and predicted to derive from actOPCs. Relative to developing OPCs, both actOPCs and hOPCs are less active metabolically and have less open chromatin.

In adulthood, these two groups are transcriptionally but not epigenetically distinct, indicating that they may represent different states of the same OPC population. If that is the case, then one model is that the parenchymal environment maintains adult OPCs within an hOPC state, whereas those OPCs recruited into white matter or exposed to demyelinated axons may transition toward an actOPC state in preparation for making new oligodendrocytes. We do not yet know the functional ramifications of these differences, but this finding has clear implications for the development of therapeutic strategies for adult remyelination.

opcs

Another finding is that developing but not adult actOPC chromatin is preferentially open for binding motifs associated with neural stem cells, transit-amplifying precursors, and neurogenesis. Although this may simply reflect their origin as the immediate progeny of neonatal neural precursor cells, it may also explain why developing but not adult OPCs have the capacity to make neurons in culture.

If we could, at least in part, reverse the global chromatin shutdown that occurs between development and adulthood, then perhaps adult OPCs may reacquire the ability to make neurons or become better able to generate new oligodendrocytes for remyelination.”

https://www.cell.com/stem-cell-reports/fulltext/S2213-6711(24)00077-8 “Single-cell approaches define two groups of mammalian oligodendrocyte precursor cells and their evolution over developmental time”

Continued in Part 2.

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Changing a cancerous phenotype

gettingwell4 4-5 stars Advanced knowledge, Acetylcholine, Epigenetics, Glutamate, Immune system, Neurochemicals, Stress , ,

A 2024 Dr. Goodenowe presentation to a professional audience. He ended the presentation by using his 86-year-old father as a case study of treatment to create an inhospitable environment for cancer.

1. Get the body ready

slide 189

2. Starve the cancer and boost the immune system

slide 190

3. Characteristics

slide 191

4. 2019 sample biochemistry

slide 192

5. 2023 biochemistry (compare HDL (33 vs. 80), see off-the-chart hsCRP, Hcy 16)

slide 193

6. Treatment details #1

slide 197

7. Treatment details #2

slide 198

https://drgoodenowe.com/tfim-2024-recording-now-available/ “Breaking Cancer: The Biochemistry of Cancer Risk Assessment, Prevention, and Treatment—Real Knowledge That You Can Use In Your Practice”

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Sulforaphane’s effects on autism and liver disease

gettingwell4 4-5 stars Advanced knowledge, Brain development, Epigenetics, Glutamate, Immune system, Neurochemicals, Stress ,

Here are two more papers that cited Precondition your defenses with broccoli sprouts, starting with a 2024 human / rodent study investigating gut microbiota / sulforaphane’s effects on autism:

“Sulforaphane (SFN) has been found to alleviate complications linked with several diseases by regulating gut microbiota (GM), while the effect of GM on SFN for autism spectrum disorders (ASD) has not been studied. We evaluated therapeutic effects of SFN on maternal immune activation (MIA)-induced ASD-like rat model and pediatric autism patients aged 4–7 years.

OSU-SO for social interactive OSU behavioral subscores, OSU-CO for non-verbal communicative OSU behavioral [significant] subscores, and OSU-ST for repetitive or ritualistic OSU behavioral subscores:

fnut-10-1294057-g0005

Although gut microbiota composition was significantly altered in SFN-treated ASD-like rats, alteration of GM was not evident in ASD patients after 12 weeks of SFN treatment. Limitations in this study:

  1. Studies were conducted in male rats and boys only;
  2. The sample size of our clinical study is relatively small [6 SFN-treated boys] and needs to be further expanded in the future; and
  3. This study only uncovered a potential link between gut flora and the therapeutic effects of SFN on ASD.

SFN treatment alleviates social deficits in MIA-induced ASD-like rats and ASD patients, and improvements might be associated with gut microbiota.”

https://www.frontiersin.org/articles/10.3389/fnut.2023.1294057/full “Therapeutic efficacy of sulforaphane in autism spectrum disorders and its association with gut microbiota: animal model and human longitudinal studies”

The 2022 Efficacy of Sulforaphane in Treatment of Children with Autism Spectrum Disorder: A Randomized Double-Blind Placebo-Controlled Multi-center Trial (not freely available) was referenced for sulforaphane (actually, glucoraphanin with myrosinase enzyme) doses:

“Dosing was weight-based:

  • Two tablets/day for 10–29 lb;
  • Three tablets/day for 30–49 lb;
  • Four tablets/day for 50–69 lb.

An estimated delivery of approximately 24, 36, and 48 μmol of sulforaphane daily was expected in the respective SF dosage groups.”

Weights of the above μmol estimated dose amounts per https://pubchem.ncbi.nlm.nih.gov/compound/sulforaphane are 4.3, 6.4, and 8.5 mg, respectively. An average weight of a 4-year-old boy is 36 lbs / 16.3 kg, and a 7-year-old boy is 51.1 lbs / 23.2 kg.

This study’s maternal immune activation was done by injecting lipopolysaccharide into pregnant rats. Would injecting pregnant women with immune-activating substances have similar harmful effects on the fetus? We don’t have evidence because unbiased and unconflicted studies looking for such effects weren’t sponsored and/or published before immune-activating substances’ deployments.

A 2024 rodent study investigated sulforaphane’s effects on diabetic liver damage:

“We investigated whether sulforaphane, an Nrf2 activator and antioxidant, prevents diabetes-induced hepatic ferroptosis, and the mechanisms involved. Results showed that diabetes-induced inactivation of Nrf2 and decreased expression of its downstream antiferroptotic molecules critical for:

  • Antioxidative defense (catalase, superoxide dismutases, thioredoxin reductase);
  • Iron metabolism (ferritin heavy chain (FTH1), ferroportin 1);
  • Glutathione (GSH) synthesis (cystine-glutamate antiporter system, cystathionase, glutamate-cysteine ligase catalitic subunit, glutamate-cysteine ligase modifier subunit, glutathione synthetase); and
  • GSH recycling – glutathione reductase (GR)

were reversed/increased by sulforaphane treatment.

Diabetes-induced increases in serum glucose and triglyceride levels were also significantly reduced by sulforaphane. Taken together, our results demonstrate a potent effect of SFN in inhibiting ferroptotic death of hepatocytes under diabetic conditions in vivo, thereby alleviating liver injury.

This is the first study to demonstrate the protective role of SFN against ferroptosis in the liver of diabetic mice. This nominates sulforaphane as a promising phytopharmaceutical for the prevention/alleviation of ferroptosis in diabetes-related pathologies.”

https://iubmb.onlinelibrary.wiley.com/doi/10.1002/biof.2042 “Sulforaphane prevents diabetes-induced hepatic ferroptosis by activating Nrf2 signaling axis”