Nrf2 Week #7: Immunity

Two reviews of Nrf2 relationships with our two immune systems, starting with adaptive immunity:

“We highlight recent findings about the influence of Keap1 and Nrf2 in development and effector functions of adaptive immune cells, T lymphocytes and B lymphocytes. We summarize Nrf2 research potential and targetability for treating immune pathologies.

Immune cells have mechanisms in place to strike a perfect redox balance, and to modulate levels of ROS differentially during their naive, activated, and effector stages for tailored immune responses. Cells of the lymphoid lineage (T, B, and NK cells) and myeloid lineage (macrophages, granulocytes, dendritic cells, and myeloid-derived suppressor cells) are generated from self-renewing progenitors, hematopoietic stem cell (HSCs) in the bone marrow.

Nrf2 activation in HSCs skews hematopoietic differentiation toward the myeloid lineage at the cost of the lymphoid lineage cells. Nrf2 does not participate in late T cell development leading to generation of single-positive CD4 and CD8 T cells.


  • Nrf2 activation supports differentiation of the Th2 subset, regulatory T cells (Tregs), and the NKT2 subset while inhibiting differentiation of Th1, Th17, NKT1, and NKT17 subsets.
  • The absence of or low Nrf2 results in enhanced proinflammatory responses, characterized by differentiation of Th1, Th17, NKT1, and NKT17 subsets, and subdued generation of Th2, Treg, and NKT2 subsets.

Nrf2 activation levels also influence generation of humoral responses.

  • Low Nrf2 levels favor T cell–dependent production of IgG and IgM Abs by activated B cells.
  • High Nrf2 suppresses B cell responses such as differentiation of germinal center B cells and plasma cells.

Nrf2 negatively regulates T–cell mediated inflammatory responses and T-dependent B cell responses. “Beyond Antioxidation: Keap1–Nrf2 in the Development and Effector Functions of Adaptive Immune Cells”

And our innate immune system:

“Nrf2 regulates the immune response by interacting directly or indirectly with one or more of the major innate immune signaling components that maintain cellular homeostasis. Toll-like receptors (TLR) signaling can induce Nrf2 activation, and this is primarily found to be through autophagy-mediated degradation of Keap1.

TLR agonists may be considered as stimuli that induce Nrf2 to reduce stress and inflammation, linking the immune and antioxidant pathways. Conversely, Nrf2 activation may restrain TLR-mediated inflammatory response through induction of antioxidant proteins and inhibition of pro-inflammatory cytokines.

Following LPS stimulation, the NF-κB pathway is engaged to initiate a host of pro-inflammatory responses such as IL-6 and interleukin 1 beta (IL-1β) gene expression. Nrf2 induction inhibits LPS-mediated activation of pro-inflammatory cytokines in macrophages.

Inflammasome activation is an essential component of the innate immune response, and is critical for clearance of pathogens or damaged cells through pro-inflammatory cytokine secretion and/or cell-death induction. While Nrf2 activation is in general associated with an anti-inflammatory state, Nrf2 has also been reported to be required for optimal NLRP3 inflammasome activity.

The type-I interferon (IFN) system constitutes an essential part of innate immunity. Type-I IFNs are produced upon recognition of foreign or self-DNA or RNA, and are best-known for inducing an antiviral state through the induction of interferon-stimulated genes. While Nrf2 interferes with IRF3 activation, STING expression, and type-I IFN signaling, none of these crucial players in innate immunity have been demonstrated to be direct targets of Nrf2.

The antiviral effect of Nrf2 activation by 4-OI may use various pathways to limit viral replication that have not been identified yet. It is important to consider that Nrf2-activating metabolites may also act as immunomodulators in a Nrf2-independent manner.

Anti-inflammatory properties of Nrf2 are independent of redox control. Further mechanistic studies are needed to decipher the exact indirect and/or direct interactions between Nrf2 and innate immune players.” “Regulation of innate immunity by Nrf2”

Nrf2 Week #6: Phytochemicals

This 2023 review explored Nrf2 relationships with plant chemicals:

“This review focuses on possible mechanisms of Nrf2 activation by natural phytochemicals in preventing or treating chronic diseases, and regulating oxidative stress. Excess oxidative stress is closely related to many kinds of chronic diseases, such as cardiovascular diseases, cancer, neurodegenerative diseases, diabetes, obesity, and other inflammatory diseases.

Mitochondrial dysfunction and hyperglycemia lead to the massive production of ROS, which triggers molecular damage, inflammation, ferroptosis, insulin resistance, and β-cell dysfunction.


Crosstalk between Keap1-Nrf2-ARE pathway and other signaling pathways endows it with high complexity and significance in the multi-function of phytochemicals. Limited human data makes an urgent need to open the new field of phytochemical-original supplement application in human chronic disease prevention.” “The Regulatory Effect of Phytochemicals on Chronic Diseases by Targeting Nrf2-ARE Signaling Pathway”

Top ten mentions, not including references:

  • 21 Sulforaphane
  • 16 Broccoli
  • 9 Curcumin
  • 5 Resveratrol
  • 5 Green tea catechins
  • 4 Luteolin
  • 3 Garlic
  • 3 Soy isoflavones
  • 3 Lycopene
  • 3 Quercetin


Nrf2 Week #5: Elements

Two 2023 papers, starting with a cell study of Nrf2 regulating sulfur:

“We demonstrated that NRF2 increased intracellular persulfides by upregulating cystine transporter xCT encoded by Slc7a11, a well-known NRF2 target gene. Persulfides have been shown to play an important role in mitochondrial function.

Supplementation with glutathione trisulfide (GSSSG), which is a form of persulfide, elevated mitochondrial membrane potential, increased oxygen consumption rate (OCR), and promoted ATP production.

glutathione trisulfide

The sulfur oxidation pathway is thought to protect cells from sulfide toxicity and to support electron transport efficiency. This study clarified that facilitating persulfide production and sulfur metabolism in mitochondria by increasing cysteine availability is one of the mechanisms for NRF2-dependent mitochondrial activation.” “Contribution of NRF2 to sulfur metabolism and mitochondrial activity”

The second paper reviewed Nrf2 regulating iron:

“The central role of Nrf2 in dictating multiple facets of cellular stress response has defined the Nrf2 pathway as a general mediator of cell survival. Ferroptosis is an iron- and lipid peroxidation-dependent form of cell death. While Nrf2 was initially thought to have anti-ferroptotic function primarily through regulating antioxidant response, accumulating evidence has indicated that Nrf2 also exerts anti-ferroptotic effects via regulating key aspects of iron and lipid metabolism.


Iron exists in two redox states, ferrous (Fe2+) and ferric (Fe3+). While constant loss or gain of electrons to switch between two redox states makes iron useful for metabolic reactions, generation of free radicals due to an excess of the highly reactive Fe2+ form is toxic to cells. To prevent iron toxicity, free labile iron in the form of (Fe2+) is controlled by multiple systems at both systemic and cellular levels to maintain iron homeostasis.

Nrf2 regulates iron homeostasis by controlling both ferritin synthesis and degradation. Overall, Nrf2 regulation of iron homeostasis is a critical determinant of a cell’s sensitivity or resistance to ferroptosis, which is independent of its antioxidant function.” “Anti-Ferroptotic Effects of Nrf2: Beyond the Antioxidant Response”


Nrf2 Week #3: Epigenetics

To follow the Nrf2 Week #2 finding that chromatin accessibility parallels Nrf2 expression, this 2023 cell study explored how Nrf2 influences other epigenetic processes:

“We identified antioxidant response element sequences in promoter regions of genes encoding several epigenetic regulatory factors, such as histone deacetylases (HDACs), DNA methyltransferases (DNMTs), and proteins involved in microRNA biogenesis.

  • We treated cells with dimethyl fumarate (DMF), an activator of the NRF2 pathway through both the KEAP1 and GSK-3 pathways. NRF2 is able to modulate expression of HDAC1, HDAC2, HDAC3, and SIRT1 in different cell types.
  • DMF treatment induced DNMT1 and DNMT3b at both mRNA and protein levels. For DNTM3a, there was a slight induction of mRNA levels but not at the protein level.


  • Our data indicate that of all miRNAs analyzed, only miR-27a-3p, miR-27b-3p, miR-128-3p, and miR-155-5p associate with Nfe2l2 mRNA. NRF2 causes degradation of miR-155-5p, which is implicated in neuroinflammation and other pathologies, and is the main miRNA induced by LPS treatment in microglia. miR-155 alters expression of genes that regulate axon growth, supporting the bioinformatic prediction that miR-155 can regulate expression of genes involved in central nervous system development and neurogenesis.

Todate we only understand how epigenetic modifications affect expression and function of the NRF2 pathway. The fact that NRF2 can promote expression of type I HDACs, DNMTs, and proteins involved in miRNA biogenesis opens new perspectives on the spectrum of actions of NRF2 and its epigenetic influences.” “The Transcription Factor NRF2 Has Epigenetic Regulatory Functions Modulating HDACs, DNMTs, and miRNA Biogenesis”


Nrf2 Week #2: Neurons

To follow the Nrf2 Week #1 suggestion that Nrf2 target neurological disorders, this 2023 cell study investigated Nrf2 expression in neurons:

“Oxidative metabolism is inextricably linked to production of reactive oxygen species (ROS), which have the potential to damage all classes of macromolecules. Yet ROS are not invariably detrimental. Several properties make ROS useful signaling molecules, including their potential for rapid modification of proteins and close ties to cellular metabolism.

We used multiple single cell genomic datasets to explore Nrf2 expression and regulation in hundreds of neuronal and non-neuronal cell types in mouse and human. With few exceptions, Nrf2 is expressed at far lower levels in neurons than in non-neuronal support cells in both species.

This pattern is maintained in multiple disease states, and the chromatin accessibility landscape at the Nrf2 locus parallels these expression differences. These results imply that Nrf2 activity is limited in almost all neurons of the mouse and human central nervous system (CNS).

nrf2 expression

We separated cell types into neuron or non-neuronal ‘support’ cell categories. The general ‘support’ term is not meant to minimize the functional relevance of non-neuronal cells in the CNS, but is an umbrella term meant to cover everything from glial cell types (astrocytes, microglia, oligodendrocytes) to endothelial cells.

It is not clear why an important, near ubiquitous cytoprotective transcription factor like Nrf2 remains off in mature neurons, especially considering oxidative stress is a driver of many diseases. The simplest explanation is that Nrf2 activity also disrupts normal function of mature neurons.

ROS play a key role in controlling synaptic plasticity in mature neurons. These activity-dependent changes in synaptic transmission, which are important for learning and memory, are disrupted by antioxidants.

A subset of important Nrf2-targeted antioxidant genes (e.g., Slc3a2, Slc7a11, Nqo1, Prdx1) are also low in neurons. So it is likely that these and/or other Nrf2 targets must remain low or non-ROS-responsive in mature neurons. Future work exploring why this expression pattern persists in mature neurons will inform our models on roles of antioxidant genes in normal neuronal physiology and in neurological disorders. “Limited Expression of Nrf2 in Neurons Across the Central Nervous System”


Nrf2 Week #1: Targeting

It’s been a while since I curated Nrf2 research. Read almost a dozen relevant 2023 papers last week. Let’s begin with an opinion paper by a highly qualified researcher:

“The inducible transcription factor nuclear factor erythroid 2-related factor 2 (NRF2) regulates expression of several hundred genes encoding proteins with antioxidant, anti-inflammatory, drug metabolising, and other homeostatic functions. Through its transcriptional targets, NRF2 activation orchestrates a comprehensive and long-lasting protection that allows adaptation and survival under diverse forms of cellular and organismal stress.

We highlight three NRF2 activators that have progressed furthest in clinical development. Overall outcomes of clinical trials with sulforaphane-rich preparations have strengthened preclinical evidence that sulforaphane has the potential to prevent toxic and neoplastic effects of environmental carcinogens, as well as to ameliorate conditions characterised by chronic oxidative, metabolic, and inflammatory stress.

Anti-inflammatory effects of most electrophilic NRF2 activators are partly NRF2-independent, and include inhibition of other inflammatory mediators. The majority of non-electrophilic PPI inhibitors are less potent in activating NRF2 in cellular systems than the electrophilic sulforaphane.

It remains to be shown that measurement of NRF2 activation in blood samples can reflect modulation of the pathway in target tissues. The field has yet to reach a consensus on the best approach for monitoring NRF2 activation in humans, including selection of the optimal panel of gene/protein targets.

Even after a single dose of an NRF2 activator, increased levels of the actual protectors (i.e., the downstream transcriptional targets of NRF2) persist over long periods of time (days), exceeding the half-life (hours) of the drug.

target disease

In certain contexts, the role of NRF2 is complex and cell-type-specific, for example, in mouse models of atherosclerosis. Considering that NRF2 activation functions to:

  • Restore cellular redox and protein homeostasis;
  • Preserve mitochondrial function; and
  • Inhibit inflammation.

Perhaps the most logical disease areas are neurological conditions where all of these processes contribute to survival of neurons and astrocytes, as well as metabolic disease and cancer prevention.” “Advances and challenges in therapeutic targeting of NRF2”


Ancient parasite DNA within us

Two 2023 papers on endogenous retroviruses (ERVs) and aging relationships, starting with the Introduction section of a comprehensive study:

“Several causal determinants of aging-related molecular changes have been identified, such as epigenetic alterations and stimulation of senescence-associated secretory phenotype (SASP) factors. Although the majority of these studies describe aging determinants originating primarily from protein-coding genes, the non-coding part of the genome has started to garner attention as well.

ERVs belonging to long terminal repeat (LTR) retrotransposons are a relic of ancient retroviral infection, fixed in the genome during evolution, comprising about 8% of the human genome. As a result of evolutionary pressure, most human ERVs (HERVs) accumulate mutations and deletions that prevent their replication and transposition function. However, some evolutionarily young subfamilies of HERV proviruses, such as the recently integrated HERVK, maintain open reading frames encoding proteins required for viral particle formation.

In this study, using cross-species models and multiple techniques, we revealed an uncharacterized role of endogenous retrovirus resurrection as a biomarker and driver for aging. Specifically, we identified endogenous retrovirus expression associated with cellular and tissue aging and that the accumulation of HERVK retrovirus-like particles (RVLPs) mediates the aging-promoting effects in recipient cells. More importantly, we can inhibit endogenous retrovirus-mediated pro-senescence effects to alleviate cellular senescence and tissue degeneration in vivo, suggesting possibilities for developing therapeutic strategies to treat aging-related disorders.” “Resurrection of endogenous retroviruses during aging reinforces senescence”

This first paper’s foreword summarized their many experiments and findings:

“The study found that HERVK transcripts, viral proteins, and RVLPs were highly activated in prematurely aged human mesenchymal progenitor cells (hPMCs). This was similarly observed in aged human primary fibroblasts and hPMCs. They also discovered that decreasing silencing epigenetic marks DNA methylation and H3K9me3 while increasing H3K36me3 enabled HERVK expression.

erv aging mechanism

These observations also raise several intriguing questions:

  • HERVK is occasionally activated and eventually suppressed under physiological conditions, for example, in human embryonic cells. It would be fascinating to probe the possibility of mimicking physiological conditions in order to turn off the positive feedback between HERVK and senescence.
  • ERVs are hallmarks of aging in different species, including human, primate, and mouse. Future quantification of the absolute physiological level of ERVs across a broad population of various ages might provide further insights into the relationship between ERVs and organismal age.” “Endogenous retroviruses make aging go viral”

Previously curated papers on these subjects include:

A study of our evolutionary remnants

“Repressive epigenetic marks associated with ERVs, particularly LTRs, show a remarkable switch in silencing mechanisms, depending on evolutionary age:

  • Young LTRs tend to be CpG-rich and are mainly suppressed by DNA methylation, whereas
  • Intermediate age LTRs are associated predominantly with histone modifications, particularly histone H3 lysine 9 (H3K9) methylation.
  • Evolutionarily old LTRs are more likely inactivated by accumulation of loss-of-function genetic mutations.”

Starving awakens ancient parasite DNA within us

Reality is sometimes stranger than what fiction writers dream up. 🙂


Eat broccoli sprouts to protect your brain from stroke

Starting this blog’s ninth year with a 2022 rodent study of sulforaphane neuroprotection:

“An example of endogenous neuroprotection is ischemia-resistance of the hippocampal regions comprising the CA2, CA3, CA4 and dentate gyrus subfields (here abbreviated to CA2-4,DG) which can be contrasted with the ischemia-vulnerable CA1 region, which is noted in rodents as well as humans.

As with CA2-4,DG, nuclear Nrf2 levels are also higher in the olfactory bulb, while in the cortex, striatum, and cerebellum, they are similar to ones observed in the CA1 region.

brain area comparative Nrf2 activity

We found an in vitro dose-dependent response to administration of sulforaphane on neuronal viability, with an optimal effect noted where the dose was 10 µM. A protective effect was also evident in vivo when a single 5 mg/kg dose of sulforaphane was administered intraperitoneally with delay to ischemia.

Morphology of the CA1 region stratum pyramidale was significantly improved in comparison to ischemia-operated group, with mean numbers of proper cells being 35 ± 19 and 20 ± 7, respectively, for subjects injected during ischemia or 30 min into reperfusion. Morphology of the CA2-4,DG region did not reveal change between the ischemia-operated, SFN-injected, and control groups.

We suggest that high levels of nuclear Nrf2 activity in CA2-4,DG may guarantee resistance of this region to I/R episode, while at the same time offering a potential explanation for the phenomenon of differential sensitivities of hippocampal regions. Our results are in line with the existing view that Nrf2 activation may represent a promising therapeutic strategy against cerebral ischemia.

The uniqueness of Nrf2 lies in its pleiotropic action and subsequent regulation of multiple cytoprotective pathways. This may support more efficient neuroprotection compared to single-target strategies.” “Is Nrf2 Behind Endogenous Neuroprotection of the Hippocampal CA2-4,DG Region?”

Winter beach shock therapy


Week 144 of Changing to a youthful phenotype with sprouts

Two papers, starting with a 2023 study that investigated the same red radish cultivar as Sulforaphene, a natural analog of sulforaphane:

“Availability of microgreen products is constantly rising, i.e., they are offered for sale in local farmers markets, specialty stores, and in chain grocery stores. Due to the low demands required for their cultivation and easily available LED settings, microgreens are increasingly grown on a small scale in homes and after harvesting, they are stored in kitchen refrigerators at 4 °C.

The aim of this study was to simulate such cultivation and storage conditions to examine antioxidant capacity of home-grown radish microgreens. Seven-day-old radish microgreens, grown under purple and white LED light, were harvested and stored at 4 °C for two weeks.

Measurements of total antioxidant capacity and bioactive substances were conducted on the harvesting day and on the 3rd, 7th, and 14th day of storage. All three radish cultivars (Raphanus sativus L.) with different leaf colorations:

  • Purple radish (R. sativus cult. China Rose, cvP);
  • Red radish (R. sativus cult. Sango, cvR); and
  • Green radish (Raphanus sativus var. longipinnatus, Japanese white or daikon radish, cvG)

were purchased commercially from a local supplier.

The highest contents of total soluble phenolics, proteins, and sugars, dry matter, and monomeric anthocyanin content, as well as higher overall antioxidant capacity determined in the red radish cultivar (cvR), distinguished this cultivar as the most desirable for human consumption regardless of the cultivation light spectrum.” “Antioxidant Capacity and Shelf Life of Radish Microgreens Affected by Growth Light and Cultivars”

A 2021 review summarized what was known about radishes up to then. Here’s part of its Discussion section:

“It is worth considering radish’s organoleptic characteristics since its particular flavor can influence its acceptability among consumers. The main compound associated with its characteristic pungent flavor is raphasatin, which we have found to be the most reported isothiocyanate produced from the breakdown of glucoraphasatin.

Glucoraphasatin ranked as one of the most concentrated glucosinolates in radish, particularly in its sprouts, but also present in other parts like roots and seeds. Pungency differs among radish cultivars, environmental growth factors, agronomic, and cooking practices.”

1-s2.0-S0924224421003058-gr3_lrg “Nutritional and phytochemical characterization of radish (Raphanus sativus): A systematic review”

Seeds I’ve sprouted this year so far, left to right – red radish (Sango), broccoli, red cabbage (Red Acre), yellow mustard, oat (Avena sativa):


Red radish had similar growth characteristics as broccoli. Started with 3.6 grams of seeds, which increased to 22.2 g after three days using the same soaking and rinsing protocol I use for other sprouts.


The taste of red radish was too sharp for me to eat by themselves, so I combined them with my broccoli / red cabbage / mustard sprout mix. Bumped up microwaving time to 48 seconds in a 1000 W microwave while staying short of the 60°C (140°F) myrosinase cliff.

The whole mix still had a strong radish taste, though. It was as if two whole red radishes were sliced into a small salad.

Can’t add anything more to dampen that taste and expect beneficial compounds to be unaffected. From Week 19:

A 2018 Netherlands study Bioavailability of Isothiocyanates From Broccoli Sprouts in Protein, Lipid, and Fiber Gels found:

Compared to the control broccoli sprout, incorporation of sprouts in gels led to lower bioavailability for preformed sulforaphane and iberin.”

IAW, eating protein, fats, and fiber along with microwaved broccoli sprouts wouldn’t help. A 2018 review with some of the same researchers Isothiocyanates from Brassica Vegetables-Effects of Processing, Cooking, Mastication, and Digestion offered one possible explanation for protein acting to lower broccoli sprout compounds’ bioavailability:

“In vitro studies show that ITCs can potentially react with amino acids, peptides, and proteins, and this reactivity may reduce the ITC bioavailability in protein‐rich foods. More in vivo studies should be performed to confirm the outcome obtained in vitro.”

Mixing in red radish sprouts also gave me an upset stomach five of the six mornings. So I won’t continue to sprout red radish.

That said, I’d definitely consider sprouting red radish again to accelerate isothiocyanate treatment of problems where symptoms are much worse than an upset stomach, such as:

  • Neurogenerative diseases with their cognitive decline;
  • Immune system disorders;
  • Bacterial and viral infections; and
  • Other damage caused by oxidative stress conditions in eyes, vascular system, kidney function, etc.

Piping in the New Year


Eat mushrooms every day?

Three 2022 papers on amino acid ergothioneine, starting with a human study:

“We examined temporal relationships between plasma ergothioneine (ET) status and cognition in a cohort of 470 elderly subjects attending memory clinics in Singapore. All participants underwent baseline plasma ET measurements as well as neuroimaging for cerebrovascular disease (CeVD) and brain atrophy. Neuropsychological tests of cognition and function were assessed at baseline and follow-up visits for up to five years.

Lower plasma ET levels were associated with poorer baseline cognitive performance and faster rates of decline in function as well as in multiple cognitive domains including memory, executive function, attention, visuomotor speed, and language. In subgroup analyses, longitudinal associations were found only in non-demented individuals.

Mediation analyses showed that effects of ET on cognition seemed to be largely explainable by severity of concomitant CeVD, specifically white matter hyperintensities, and brain atrophy. Our findings support further assessment of plasma ET as a prognostic biomarker for accelerated cognitive and functional decline in pre-dementia and suggest possible therapeutic and preventative measures.” “Low Plasma Ergothioneine Predicts Cognitive and Functional Decline in an Elderly Cohort Attending Memory Clinics”

Earlier this year, two of the study’s coauthors put together a collection of 11 ergothioneine papers:

“One catalyst for this upsurge of interest was the discovery in 2005 of a transporter for ET (OCTN1, often now called the ergothioneine transporter, ETT), which accounts for the fact that animals (including humans) take up and avidly retain ET from the diet. The presence of a specific transporter together with the avid retention of ET in the body implies that this compound is important to us.

To quote an old phrase ‘correlation does not imply causation.’ Low ET levels may predispose to disease, but disease could also lead to low ET levels. Possible reasons could include:

  • Alterations in diet due to illness so that less ET is consumed;
  • Decreases in ETT activity in the gut (leading to less ET uptake) or kidney (impairing ET reabsorption) with age and disease.
  • Changes in gut microbiota might influence uptake and accumulation in the body.
  • ET is being consumed as it scavenges oxygen radicals and other reactive oxygen species, the production of which is known to increase in these diseases and during ageing in general.

Only the gold standard of placebo-controlled double-blinded clinical studies can definitively establish the value (if any) of ET in preventing or treating human disease. Several such trials are being planned or in progress; we await the results with interest, and a streak of optimism.” “Ergothioneine, where are we now?”

One of the collection’s papers focused on what ETT research findings could or could not be replicated:

“ETT is not expressed ubiquitously and only cells with high ETT cell-surface levels can accumulate ET to high concentration. Without ETT, there is no uptake because the plasma membrane is essentially impermeable. We review substrate specificity and localization of ETT, which is prominently expressed in neutrophils, monocytes/macrophages, and developing erythrocytes.

Comparison of transport efficiency (TE) for acknowledged substrates of the ETT. Bar length represents approximate TE of wild-type human ETT.


We have not found in the literature any other ET transporters. However, it is highly probable that additional ET transporters work in the human body:

  • Uptake of ET from the small intestine into epithelial cells occurs through apically localized ETT. The very hydrophilic ET cannot then exit these cells toward the blood without help – a basolateral efflux transporter is required.
  • After oral administration of 3H-ET, a considerable amount of ET was still absorbed into the body in the ETT KO [knockout] mice. There must be another transporter for apical uptake at least in the small intestine of the mouse.
  • When ET was administered intravenously, ETT KO mice showed no change in ET concentration in the brain compared to wild type. The little ET that enters the brain must therefore pass through the BBB via a different transporter.” “The ergothioneine transporter (ETT): substrates and locations, an inventory”

It’s persuasive that there’s an evolutionarily conserved transmitter specific to ergothioneine. It isn’t persuasive that this compound once consumed is almost always in stand-by mode to do: what?

Ergothioneine isn’t a substitute for the related glutathione, especially since its supply isn’t similarly available from an endogenous source. It isn’t an active participant in day-to-day human life.

Still, I hedge my bets. I eat ergothioneine every day via white button mushrooms in AGE-less chicken vegetable soup at a cost of about $1.30.


Eat broccoli sprouts to epigenetically regulate histones

Five papers on beneficial effects from sulforaphane inhibiting histone deacetylases (HDACs), starting with a 2022 rodent cell study:

“Sulforaphane (SFN) has tissue specificity for subtypes of HDACs that are downregulated. For example:

  • In breast cancer cells, HDAC1-3 are inhibited by SFN to induce cell apoptosis;
  • In skin cells, HDAC1-4 are regulated by SFN [anti-skin cancer]; and
  • In the cochlea, SFN inhibits HDAC2, 4, and 5 [attenuates hearing loss].

In the present study, SFN significantly inhibited HDAC2, 3, and 5 expression and HDACs activity in cardiomyocytes, thereby increasing H3 acetylation levels in the Nrf2 promoter and upregulating Nrf2 expression. Mechanism by which SFN prevents Ang II-induced cardiomyocyte apoptosis:

  • Ang II activates oxidative stress by increasing ROS leading to inflammation, oxidative stress and fibrosis in cardiomyocytes.
  • SFN prevents Ang II-induced cardiomyocyte apoptosis by inhibiting HDACs to activate Nrf2 and downstream antioxidant genes.


SFN activates Nrf2 by inhibiting HDACs expression and activation.” “Sulforaphane inhibits angiotensin II-induced cardiomyocyte apoptosis by acetylation modification of Nrf2”

A 2021 rodent study found:

“SFN significantly attenuated diabetes-induced renal fibrosis in vivo. SFN inhibited diabetes-induced increase in HDAC2 activity.

Bone morphologic protein 7 (BMP-7) has been shown to reduce renal fibrosis induced by transforming growth factor-beta1. SFN protects against diabetes-induced renal fibrosis through epigenetic up-regulation of BMP-7.”

dmj-2020-0168f7 “Sulforaphane Ameliorates Diabetes-Induced Renal Fibrosis through Epigenetic Up-Regulation of BMP-7”

A 2019 human osteosarcoma cell study found:

“SFN inhibits mTOR in a concentration- and time-dependent manner. This inhibition occurs in the presence or in the absence of NRF2.

SFN inhibits HDAC6 and decreases catalytic activity of AKT, which partially explains the mechanism by which SFN inhibits mTOR.” “The isothiocyanate sulforaphane inhibits mTOR in an NRF2-independent manner”

A 2022 review cited a 2018 cell study:

“HDAC expression and activity are dysregulated in various diseases including asthma, chronic obstructive pulmonary disease, cancer, cardiac hypertrophy, and neurodegenerative and psychological disorders. HDAC inhibitors could be a potential therapeutic target for many diseases.

In hypertension, aortic stiffness is usually increased and vascular smooth muscle cells (VSMCs) contribute to vascular stiffness. We used VSMCs to test the degree of acetylation of histones in this study.

Sulforaphane weakly inhibited HDAC2 and effectively inhibited HDAC9.” “Zinc-dependent histone deacetylases: Potential therapeutic targets for arterial hypertension” “Inhibition of class IIa histone deacetylase activity by gallic acid, sulforaphane, TMP269, and panobinostat” (not freely available)


What do we know about human aging from mouse models?

Here is a 2021 rodent study and relevant parts from 3 of its 26 citing papers:

“A long line of evidence has established the laboratory mouse as the prime model of human aging. However, relatively little is known about detailed behavioral and functional changes that occur across their lifespan, and how this maps onto the phenotype of human aging.

To better understand age-related changes across the lifespan, we characterized functional aging in male C57BL/6J mice of five different ages (3, 6, 12, 18, and 22 months of age) using a multi-domain behavioral test battery. Assessment of functional aging in humans and mice: age-related patterns were determined based on representative data (Table 2), and then superimposed onto survival rate. (A) Body weight, (B) locomotor activity, (C) gait velocity, (D) grip strength, (E) trait anxiety, (F) memory requiring low attention level, and (G) memory requiring high attention level.


These functional alterations across ages are non-linear, and patterns are unique for each behavioral trait. Physical function progressively declines, starting as early as 6 months of age in mice, while cognitive function begins to decline later, with considerable impairment present at 22 months of age.

Functional aging of male C57BL/6J mice starts at younger relative ages compared to when it starts in humans. Our study suggests that human-equivalent ages of mice might be better determined on the basis of its functional capabilities.” “Functional Aging in Male C57BL/6J Mice Across the Life-Span: A Systematic Behavioral Analysis of Motor, Emotional, and Memory Function to Define an Aging Phenotype”

“Studies in mice show that physical function (i.e., locomotor activity, gait velocity, grip strength) begins to deteriorate around post-natal day (PND) 180, but cognitive functions (i.e., memory) do not exhibit impairment until roughly PND 660. Our results should be considered within the context of behavior changing throughout vole adulthood. Caution should be taken to avoid categorizing the oldest age group in our study as ‘elderly’ or ‘geriatric.'” “Behavioral trajectories of aging prairie voles (Microtus ochrogaster): Adapting behavior to social context wanes with advanced age”

“We used adult mice ranging in age from 5-6 months, not enough to modify experimental autoimmune encephalomyelitis progression. Mice are considered adult after 8 weeks; however, rapid growth for most biological processes is observed until 3 months of age, while past 6 months, mice might be affected by senescence.” “Age related immune modulation of experimental autoimmune encephalomyelitis in PINK1 knockout mice”

“Locomotor activity and gait velocity of 12 months old male C57BL/6 correlates with an elderly human being aged 60 or older, supporting that the ~15 months old mice we used in our study were aged mice at the time of tissue collection.” “Genomic Basis for Individual Differences in Susceptibility to the Neurotoxic Effects of Diesel Exhaust”


Broccoli sprouts activate the AMPK pathway, Part 4

Today someone viewed the 2020 Part 3 of Broccoli sprouts activate the AMPK pathway which lacked citations at the time. Checking again, here are three citing 2022 papers, starting with a review:

“Nrf2 is an important transcription factor that regulates expression of a large number of genes in healthy and disease states. Nrf2 regulates expression of several key components of oxidative stress, mitochondrial biogenesis, mitophagy, autophagy, and mitochondrial function in all organs of the human body, and in the peripheral and central nervous systems.

Overall, therapeutic drugs including sulforaphane that target Nrf2 expression and Nrf2/ARE pathway are promising. This article proposes additional research in Nrf2’s role within Parkinson’s disease, Huntington’s disease, and ischemic stroke in preclinical mouse models and humans with age-related neurodegenerative diseases.” “Role of Nrf2 in aging, Alzheimer’s and other neurodegenerative diseases” (not freely available) Thanks to Dr. P. Hemachandra Reddy for providing a copy.

One of the Part 3 study’s coauthors contributed to this very detailed review:

“Due to observed overlapping cellular responses upon AMPK or NRF2 activation and common stressors impinging on both AMPK and NRF2 signaling, it is plausible to assume that AMPK and NRF2 signaling may interdepend and cooperate to readjust cellular homeostasis.


The outcome and underlying signaling events of AMPK-NRF2 crosstalk may diverge between:

  1. in vitro and in vivo studies (one cell type in isolation vs inter-organ crosstalk in living organisms);
  2. Different cell types/organs/organisms of different cultivation conditions, genetic background, age or sex;
  3. Different stress-regimens (chronic vs acute, nature of stress (lipotoxicity, redox stress, xenobiotic, starvation, etc));
  4. Different modes of Nrf2 or AMPK activation and inhibition (genetic vs pharmacological, constitutive vs transient/intermittent, systemic vs organ-specific, electrophilic vs PPI, allosteric vs covalent, or pan vs subtype-specific);
  5. Different target genes with distinct promoter and enhancer structure; or
  6. Different timing of activation.

The latter should deserve increased attention as Nrf2 is one of the most cycling genes under control of the circadian clock. Feeding behavior, metabolism and hence AMPK activity follow and substantiate the biological clock, indicating an entangled circadian regulation of metabolic and redox homeostasis.” “AMPK and NRF2: Interactive players in the same team for cellular homeostasis?”

A third citing paper was a study of lens cells that provided an example of similar metformin effects noted in Part 2 of Broccoli sprouts activate the AMPK pathway:

“Loss of Nrf2 and Nrf2 antioxidant genes expression and activity in aging cells leads to an array of oxidative-induced deleterious responses, impaired function, and aging pathologies. This deterioration is proposed to be the primary risk factor for age-related diseases such as cataracts.

AMPK regulates energy at physiological levels during metabolic imbalance and stress. AMPK is a redox sensing molecule, and can be activated under cellular accumulation of reactive oxygen species, which are endogenously produced due to loss of antioxidant enzymes.

The therapeutic potential of AMPK activation has context-dependent beneficial effects, from cell survival to cell death. AMPK activation was a requisite for Bmal1/Nrf2-antioxidants-mediated defense, as pharmacologically inactivating AMPK impeded metformin’s effect.

Using lens epithelial cell lines (LECs) of human or mouse aging primary LECs along with lenses as model systems, we demonstrated that metformin could correct deteriorated Bmal1/Nrf2/ARE pathway by reviving AMPK-activation and transcriptional activities of Bmal1/Nrf2, resulting in increased antioxidants enzymatic activity and expression of Phase II enzymes. Results uncovered crosstalk between AMPK and Bmal1/Nrf2/antioxidants mediated by metformin for blunting oxidative/aging-linked pathobiology.” “Obligatory Role of AMPK Activation and Antioxidant Defense Pathway in the Regulatory Effects of Metformin on Cellular Protection and Prevention of Lens Opacity”


All about walnuts’ effects

Five 2022 papers focusing on walnuts, starting with a comparison of eight tree nuts:

“The aim of the present study was to examine 8 different popular nuts – pecan, pine, hazelnuts, pistachio, almonds, cashew, walnuts, and macadamia. Total content of phenolic compounds in nuts ranged from 5.9 (pistachio) to 432.9 (walnuts) mg/100 g.

Walnuts had the highest content of polymeric procyanidins, which are of great interest as important compounds in nutrition and biological activity, as they exhibit antioxidant, anti-inflammatory, antimicrobial, cardio- and neuroprotective action. Walnuts are good sources of fatty acids, especially omega-3 and omega-6.” “Nuts as functional foods: Variation of nutritional and phytochemical profiles and their in vitro bioactive properties”

A second study compared the same eight tree nuts plus Brazil nuts and peanuts:

“The highest total content of all analyzed flavonoids was determined in walnuts (114.861 µg/g) with epicatechin the most abundant, while the lowest was in almonds (1.717 µg/g). Epicatechin has antioxidant, anti-inflammatory, antitumor, and anti-diabetic properties. Epicatechin has beneficial effects on the nervous system, enhances muscle performance, and improves cardiac function.” “The Content of Phenolic Compounds and Mineral Elements in Edible Nuts”

Next, two systematic reviews and meta-analyses of human studies:

“We carried out a systematic review of cohort studies and randomized controlled trials (RCTs) investigating walnut consumption, compared with no or lower walnut consumption, including those with subjects from within the general population and those with existing health conditions, published from 2017 to 5 May 2021.

  • Evidence published since 2017 is consistent with previous research suggesting that walnut consumption improves lipid profiles and is associated with reduced CVD risk.
  • Evidence pointing to effects on blood pressure, inflammation, hemostatic markers, and glucose metabolism remains conflicting.
  • Evidence from human studies showing that walnut consumption may benefit cognitive health, which is needed to corroborate findings from animal studies, is now beginning to accumulate.” “Walnut consumption and health outcomes with public health relevance – a systematic review of cohort studies and randomized controlled trials published from 2017 to present”

“We aimed to perform a systematic review and meta-analysis of RCTs to thoroughly assess data concerning effects of walnut intake on selected markers of inflammation and metabolic syndrome in mature adults. Our findings showed that:

  • Walnut-enriched diets significantly decreased TG, TC, and LDL-C concentrations, while HDL-C levels were not significantly affected.
  • No significant changes were noticed on anthropometric, cardiometabolic, and glycemic indices after higher walnut consumption.
  • Inflammatory biomarkers did not record statistically significant results.” “Walnut Intake Interventions Targeting Biomarkers of Metabolic Syndrome and Inflammation in Middle-Aged and Older Adults: A Systematic Review and Meta-Analysis of Randomized Controlled Trials”

Finishing with a rodent study that gave subjects diabetes with a high-fat diet, then mixed two concentrations of walnut extract in with the treatment groups’ chow:

“This study was conducted to evaluate the protective effect of Gimcheon 1ho cultivar walnut (GC) on cerebral disorder by insulin resistance, oxidative stress, and inflammation in HFD-induced diabetic disorder mice. After HFD feed was supplied for 12 weeks, samples were orally ingested for 4 weeks to GC20 and GC50 groups (20 and 50 mg/kg of body weight, respectively).

  • Administration of GC improved mitochondrial membrane potential function, and suppressed oxidative stress in the brain.
  • GC inhibited hepatic and cerebral lipid peroxidation and the formation of serum AGEs, and increased serum antioxidant activity to improve HFD-induced oxidative stress.
  • The HFD group showed significant memory impairment in behavioral tests. On the other hand, administration of GC showed improvement in spatial learning and memory function.

walnut brain effects

Based on these physiological activities, GC showed protective effects against HFD-induced diabetic dysfunctions through complex and diverse pathways.” “Walnut Prevents Cognitive Impairment by Regulating the Synaptic and Mitochondrial Dysfunction via JNK Signaling and Apoptosis Pathway in High-Fat Diet-Induced C57BL/6 Mice”

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