Month: March 2022

Epigenetic components for evaluating a person’s physical fitness

gettingwell4 4-5 stars Advanced knowledge, Epigenetics ,

This 2022 human study incorporated DNA methylation measures of four physical fitness parameters into a new epigenetic clock:

“Our work introduces new DNAm biomarkers for fitness parameters of gait speed (walking speed), hand grip strength, forced expiratory volume in one second (FEV1), and maximal oxygen uptake (VO2max). These DNAm biomarkers represent new tools for researchers with access to blood samples and interest in epigenetic components to fitness.

Our DNAm biomarker fitness parameter biomarkers are not intended to replace true physical fitness measurements. Instead, these DNAm biomarker estimates provide an epigenetic component to evaluating a person’s physical fitness. This biomarker integrates the established DNAm prediction of mortality risk GrimAge.

DNAmFitAge provides an easily interpretable tool to relate physical fitness to biological age. Adjusting DNAmFitAge for chronological age generates a novel measure of epigenetic age acceleration, FitAgeAcceleration, which is informative for physical activity level, mortality risk, coronary heart disease risk, comorbidities, and disease-free status across several large validation datasets.

ttd

The age-adjusted version FitAgeAcceleration provides a novel measure of epigenetic age acceleration explained through physical fitness. This research demonstrates biological age can be estimated using DNAm fitness parameter biomarkers which are dependent on exercise lifestyle.”

https://www.medrxiv.org/content/10.1101/2022.03.21.22272043v1.full-text “DNAmFitAge: Biological Age Indicator Incorporating Physical Fitness”

I walk quickly on the beach almost every day at > 3 mph. I occasionally see younger people eclipse my gait speed, which makes me try harder. 🙂

Year Two of Changing to a youthful phenotype with sprouts

gettingwell4 4-5 stars Advanced knowledge, Beliefs, Epigenetics, Immune system, Primal Therapy, Stress

1. I’ve eaten clinically-relevant doses of sulforaphane every day for 104 weeks now with microwaved 3-day-old broccoli, red cabbage, and mustard sprouts. That’s 8+ times longer than any sulforaphane clinical trial.

I continue to:

  • Eat Avena nuda oats for breakfast;
  • Eat 3-day-old hulled Avena sativa oat sprouts twice a day;
  • Eat AGE-less chicken vegetable soup twice a day;
  • Take supplements that promote healthspan twice a day;
  • Exercise at least 30 minutes daily;
  • Take yeast cell wall β-glucan daily, with nothing else an hour before or after; and
  • Avoid undue stress by working from home 40 hours a week in my 25th year as a professional software developer.

I’ve experienced many positive effects described in studies. Researchers keep exploring new aspects of their fields, and I look forward to more evidence on youthening during Year Three.

2. I’m not especially scientific or maniacal about the above practices, other than weighing sprouting seeds. I pay attention to people who measure everything, but won’t turn my life into a series of unfeeling experiments. As Dr. Arthur Janov said:

“What is the point of life if we cannot feel and love others? Without feeling, life becomes empty and sterile. It, above all, loses its meaning.”

3. Beginning last month, our world was subjected to yet another wave of propaganda, with predictable oppression of those who reported obvious lies and distortions. Previously exposed agendas took a back seat to regain their venom, as their effects waned in herding people toward personally devastating cliffs.

Meme perpetrators don’t care about you or me. Spending our time on their ideas, beliefs, and behaviors takes us further away from dealing with our individually motivating causes and individual truths, with real consequences: a wasted life.

Value your own one precious life. Winter is over, spring is here.

PXL_20220322_191200562

Gut microbiota knowledge through 2021

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

I’ll curate this 2022 review of what’s known and unknown about our trillions of gut microbiota through its topic headings:

“Most microbial taxa and species of the human microbiome are still unknown. Without revealing the identity of these microbes as a first step, we cannot appreciate their role in human health and diseases.

A. Understanding the Microbiome Composition and Factors That Shape Its Diversity
Effect of Diet Composition on the Microbiome Diversity

  • Macronutrients and Microbiome Diversity
  • Nutrient and Mineral Supplements and Microbiome Diversity

Stress

Drugs

Race and Host Genetics

Aging

Lifestyle

  • Exercise
  • Smoking
  • Urbanization

B. Understanding the Microbiome Function and Its Association With Onset and Progression of Many Diseases

Microbiome Association With Inflammatory and Metabolic Disorders

  • Chronic Inflammation in GIT and Beyond
  • Development of Malignant Tumors
  • Obesity
  • Coronary Artery Disease
  • Respiratory Diseases

Microbiome Role in Psychiatric, Behavioral, and Emotional Disorders

C. Understanding the Microbiome Function as Mediated by Secreted Molecules

D. Conclusion and Future Directions – A pioneering study aimed to computationally predict functions of microbes on earth estimates the presence of 35.5 million functions in bacteria of which only 0.02% are known. Our knowledge of its functions and how they mediate health and diseases is preliminary.”

https://www.frontiersin.org/articles/10.3389/fmicb.2022.825338 “Recent Advances in Understanding the Structure and Function of the Human Microbiome”

I took another test last month at the 14-month point of treating my gut microbiota better. Compared with the 7-month top level measurements, what stood out was an increase in relative abundance from 1% to 7% in the Verrucomicrophia phylum that pretty much exclusively comprises species Akkermansia muciniphilia in humans:

top 5 phylum 2-2022

This review termed Akkermansia muciniphilia relative increases as beneficial. Go with the Alzheimer’s Disease evidence didn’t.

Preventing human infections with dietary fibers inferred that insufficient dietary fiber may disproportionately increase abundance of this species. But I already eat much more fiber than our human ancestors’ estimated 100 grams of fiber every day, so lack of fiber definitely didn’t cause this relative increase.

Resistant starch therapy observed:

“Relative abundances of smaller keystone communities (e.g. primary degraders) may increase, but appear to decrease simply because cross-feeders increase in relative abundance to a greater extent.”

I’ll wait for further evidence while taking responsibility for my own one precious life.

Didn’t agree with this review’s statements regarding microbial associations with fear. These reviewers framed such associations as if gut microbiota in the present had stronger influences on an individual’s fear responses than did any of the individual’s earlier experiences. No way.

I came across this review by it citing The microbiome: An emerging key player in aging and longevity, which was Reference 25 of Dr. Paul Clayton’s blog post What are You Thinking?

Also didn’t agree with some of the doctor’s post:

  • Heterochronic parabiosis of young and old animals is wildly different from fecal transfer. Can’t really compare them to any level of detail.
  • Using a rodent young-to-old fecal microbiota transplant study to imply the same effects would happen in humans? Humans don’t live in controlled environments, so why would a young human individual’s gut microbiota necessarily have healthier effects than an old individual’s?
  • Another example was the penultimate paragraph: “By adding a mix of prebiotic fibers to your diet and maintaining a more youthful and less inflammatory microbiome you will have less inflammation, less endotoxaemia and less inflammageing. You will therefore live healthier and longer.” I’m okay with the first sentence. Equivalating the first sentence to both healthspan and lifespan increases in the second sentence wasn’t supported by any of the 45 cited references.

Advanced glycation / lipoxidation end products

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

Three papers on what can be expected from AGEs, beginning with a 2022 review:

“Carbonyl stress is a condition characterized by an increase in the steady-state levels of reactive carbonyl species (RCS) that leads to accumulation of their irreversible covalent adducts with biological molecules. In addition to causing damage directly, the RCS adducts advanced glycation end-products (AGEs) and advanced lipoxidation end-products (ALEs) elicit chronic inflammation through receptor-mediated mechanisms.

Endogenously formed RCS and AGEs/ALEs accumulation induced by hyperglycemia, hyperlipidemia, and oxidative stress have been long recognized as critical factors in pathogenesis of cardiovascular, renal, and eye complications. The role of dietary glyco/lipotoxins in vascular complications is debated, as the metabolic fate of most ingested AGEs/ALEs and RCS remains unknown, and their contribution to systemic carbonyl stress is uncertain.

rcs ages ales

Plasma glucose spikes after a meal rich in readily absorbable carbohydrates, particularly in association with an unfavorable lipid composition, may promote proinflammatory and pro-oxidant responses by inducing a transient increase in RCS levels and consequent AGE formation. As protein-bound AGEs are not easily eliminated from the body, they can eventually accumulate in vascular and metabolic tissues because of repeated cycles of nutrient-induced carbonyl stress, favoring establishment of systemic low chronic inflammation.

Post-challenge glucose excursions are associated with a transient increase in circulating RCS levels, particularly in diabetic and prediabetic individuals. Diet-induced weight loss is associated with decreases in postprandial carbonyl stress in obese subjects. Data on lean and metabolically healthy individuals are limited.”

https://www.mdpi.com/2072-6643/14/5/1061/htm “Food-Related Carbonyl Stress in Cardiometabolic and Cancer Risk Linked to Unhealthy Modern Diet”

I understand that researchers feel obligated to end papers with suggestions for future research. It’s a little irritating, though, when these are pie-in-the-sky.

People who wait for endogenous vs. exogenous AGE / ALE questions to be answered in their lifetimes are at risk for giving themselves diseases.

A second paper is a 2021 human cell study:

“Sulforaphane (SFN) found in cruciferous vegetables is a potent activator of the Nrf2 transcription factor, the master regulator of redox biology in mammalian cells. Nrf2 modulates expression of several antioxidant enzymes, such as γ-glutamylcysteine ligase (γ-GCL). This is the rate-limiting step in synthesis of the major non-enzymatic antioxidant glutathione (GSH). Silencing of Nrf2 or inhibition of GSH synthesis abolished SFN-promoted mitochondrial protection in cells exposed to methylglyoxal (MG), a pro-oxidant agent whose levels are high in several human diseases.

sfn vs mg

MG is a reactive dicarbonyl presenting both endogenous (e.g. glycolysis) and exogenous (e.g. food cooking) sources. MG induces neurotoxicity, at least in part, by affecting mitochondrial function, including a decline in oxidative phosphorylation (OXPHOS) system activity, bioenergetics failure, and redox disturbances.

We found that SFN prevented MG-induced OXPHOS dysfunction and mitochondrial redox impairment. SFN protected mitochondria of MG-challenged cells by a mechanism involving the Nrf2/γ-GCL/GSH axis.”

https://link.springer.com/article/10.1007/s11064-020-03204-x “The Isothiocyanate Sulforaphane Depends on the Nrf2/γ‑GCL/GSH Axis to Prevent Mitochondrial Dysfunction in Cells Exposed to Methylglyoxal” (not freely available)

Although this study’s 5 µM sulforaphane treatment is achievable in human plasma, that level isn’t sustainable for 24 hours as the study did in vitro. Would sulforaphane’s in vivo effects likewise prevent methylglyoxal from inducing AGEs?

A third paper is a 2022 human study:

“AGEs have been widely reported to play an important role in osteoporosis (OP). We investigated the effect of AGEs on osteoblast function and underlying mechanisms.

op lumbar vertebrae

Levels of bone mineral density (BMD), serum AGEs, and fasting blood glucose (FBG) were measured in patients with OP and healthy individuals:

  • Patients with OP had a higher level of serum AGEs and FBG compared with healthy individuals.
  • The level of serum AGEs in patients with OP was negatively correlated with BMD, but was positively correlated with FBG.
  • AGEs and serum from patients with OP markedly inhibited hFOB1.19 osteoblast cell proliferation, alkaline phosphatase production, and mineralized nodule formation.
  • Apoptosis and ferroptosis were significantly promoted by AGEs and serum from patients with OP.
  • Serum from OP patients with T2DM caused stronger effect than that from OP patients with normal FBG.

Collectively, AGEs could disrupt functions of osteoblasts by inducing cell ferroptosis, thus contributing to OP.”

https://www.spandidos-publications.com/10.3892/mmr.2022.12656 “Advanced glycation end products promote osteoporosis by inducing ferroptosis in osteoblasts”

Nanoencapsulating Brassica bioactives with Brassica membrane vesicles

gettingwell4 4-5 stars Advanced knowledge, Epigenetics, Immune system ,

Two 2022 in vitro studies from the group that published Red cabbage effects on gut microbiota, with the first nanoencapsulating sulforaphane:

“Sulforaphane (SFN) loaded into membrane vesicles derived from broccoli plants was studied to determine anti-inflammatory potential in a human-macrophage-like in vitro cell model under both normal and inflammatory conditions.

LPS increased IL-6 levels 1.86-fold. All compounds (free SFN, unloaded broccoli membrane (BM)-vesicles, and encapsulated SFN) mediated a dose-dependent reduction in IL-6, both in basal conditions [left] and simulated inflammatory conditions [right]. Encapsulated SFN had the greatest power.

Il-6 nanoencapsulated sulforaphane

These results showed that membrane vesicles by themselves had anti-inflammatory properties. Possible routes of administration of BM-vesicles loaded with SFN are parenteral, transdermal, and oral.”

https://www.mdpi.com/1422-0067/23/4/1940/htm “Membrane Vesicles for Nanoencapsulated Sulforaphane Increased Their Anti-Inflammatory Role on an In Vitro Human Macrophage Model”

A second study nanoencapsulated Bimi®, a crossbreed between broccoli and green Chinese kale:

“The aim of this work was to increase stability of isothiocyanates (ITCs) present in extracts of Bimi® edible parts by nanoencapsulation using cauliflower-derived plasma membrane vesicles.

Bimi® has emerged as a mild-flavoured option to pungent broccoli. As a raw gourmet material, Bimi® is highly and carefully selected, with part of edible production discarded.

Indole glucosinolates (GSLs) represented 81% of total GSL content. The only aliphatic GSL detected in a quantifiable amount was glucoraphanin, accounting for 19% of total GSLs.

1-s2.0-S0308814622006422-gr1_lrg

Comparisons between concentrations of ITCs in gastric and intestinal digestions:

A) 3,3-diindolylmethane (DIM);

  • Bimi® extract increased 2 times, and no differences in nanoencapsulated treatment after intestinal digestion.
  • Concentrations were 4- and 2-fold higher in the nanoencapsulated form than extract between gastric and intestinal digestions, respectively.

B) Indole-3-carbinol (I3C);

  • Bimi® extract increased 1.5 times, and nanoencapsulated treatment decreased 23% after intestinal digestion.
  • Concentrations were 3 times higher and 2 times higher in the nanoencapsulated form than extract between gastric and intestinal digestions, respectively.

C) SFN

  • Bimi® extract increased almost 10 times, and 100 times in nanoencapsulated treatment after intestinal digestion.
  • No differences between treatments after gastric digestion, but concentrations were 6 times higher in the nanoencapsulated form than extract after intestinal digestion.

Cauliflower-derived plasma membrane vesicles are able to enhance stability of ITCs through in vitro gastrointestinal digestion, improving their bioaccessibility and potential bioavailability.”

https://www.sciencedirect.com/science/article/pii/S0308814622006422 “Nanoencapsulation of Bimi® extracts increases its bioaccessibility after in vitro digestion and evaluation of its activity in hepatocyte metabolism”

Reversing hair greying

gettingwell4 4-5 stars Advanced knowledge, Epigenetics, Hypothalamus, Immune system, Limbic system, Memory, Stress, Telomeres ,

I’ll highlight this 2021 human study’s findings regarding stress:

“We profiled hair pigmentation patterns (HPPs) along individual human hair shafts, producing quantifiable physical timescales of rapid greying transitions. White/grey hairs that naturally regain pigmentation across sex, ethnicities, ages, and body regions, quantitatively define reversibility of greying in humans.

A systematic survey of two-colored hairs on the scalp of a 35-year-old Caucasian male with auburn hair color over a 2-day period yielded five two-colored hair shafts (HSs) from the frontal and temporal scalp regions. Unexpectedly, all HSs exhibited reversal. HPP analysis further showed that all HSs underwent reversal of greying around the same time period.

A retrospective assessment of psychosocial stress levels using a time-anchored visual analog scale (participants rate and link specific life events with start and end dates) was then compared to HPPs. Reversal of greying for all hairs coincided closely with decline in stress and a 1-month period of lowest stress over the past year (0 on a scale of 0–10) following a 2-week vacation.

vacay

We were also able to examine a two-colored hair characterized by an unusual pattern of complete HS greying followed by rapid and complete reversal plucked from the scalp of a 30-year-old Asian female participant with black hair. HPP analysis of this HS showed a white segment representing approximately 2 cm.

Quantitative life stress assessment revealed a specific 2-month period associated with an objective life stressor (marital conflict and separation, concluded with relocation) where the participant rated her perceived stress as highest (9–10 out of 10) over the past year. The increase in stress corresponded in time with complete but reversible hair greying.

separation

We document a complete switch-on/off phenomena during a single anagen cycle. Proteomic features of hair greying directly implicate multiple metabolic pathways that are both reversible in nature and sensitive to stress-related neuroendocrine factors.

This new method to quantitatively map recent life history in HPPs provides an opportunity to longitudinally examine the influence of recent life exposures on human biology. Additional prospective studies with larger sample sizes are needed to confirm robust reproducibility and generalizability of our findings.”

https://elifesciences.org/articles/67437 “Quantitative mapping of human hair greying and reversal in relation to life stress”

Vitamin K2 and hypertension

gettingwell4 2-3 stars Required further work, Epigenetics, Immune system ,

This 2021 rodent study investigated effects of Vitamin K2 on salt-sensitive hypertension:

“Mice were supplemented with VK2 and gut bacteria were detected by 16S rRNA. Common signaling pathway-related proteins were detected to further verify signaling pathways before validation of clinical samples.

Diets for 4 weeks were:

  • Normal group diet containing 0.5% NaCl;
  • High salt group (HS) diet containing 8% NaCl;
  • High salt diet plus VK2 supplementation group (HS_VK2) diet containing 8% NaCl and additional 0.025% VK2.

VK2 supplementation protected blood pressure and aortic vessels in salt-induced mice:

mk-4 salt

VK2 treated salt-sensitive hypertension by inhibiting the renin–angiotensin system.

fnut-08-639467-g009

Possible mechanisms of VK2 for salt-sensitive hypertension.”

https://www.frontiersin.org/articles/10.3389/fnut.2021.639467/full “Network and 16S rRNA Sequencing-Combined Approach Provides Insightal Evidence of Vitamin K2 for Salt-Sensitive Hypertension”

The form of Vitamin K2 was MK-4 per its C31H40O2 molecular formula. Data wasn’t provided to calculate a human-equivalent dose for 0.025% MK-4.

This study was part of a 2022 Gut Microbial Response to Host Metabolic Phenotypes collection which included animal studies investigating gut microbiota in contexts of β-carotene and β-sitosterol supplementation. I found this collection by it citing the 2018 rodent study GLP-1 release and vagal afferent activation mediate the beneficial metabolic and chronotherapeutic effects of D-allulose which was Reference 27 of Dr. Paul Clayton’s blog post Sweet Nothing.

Signaling pathways and disordered proteins

gettingwell4 2-3 stars Required further work, Cortisol, Epigenetics, Glutamate, Immune system, Memory, Neurochemicals, Stress , , ,

This 2022 review explored the title subject:

“Cell signaling imposes many demands on proteins that comprise these pathways, including abilities to form active and inactive states, and to engage in multiple protein interactions. Signaling often requires amplifying signals, regulating or tuning responses to signals, combining information sourced from multiple pathways, all while ensuring process fidelity.

Sensitivity, adaptability, and tunability are possible, in part, due to inclusion of intrinsically disordered regions in many proteins involved in cell signaling.  This review highlights the critical role of intrinsically disordered proteins for signaling:

  • In widely diverse organisms (animals, plants, bacteria, fungi);
  • In every category of cell signaling pathway (autocrine, juxtacrine, intracrine, paracrine, and endocrine); and
  • At each stage (ligand, receptor, transducer, effector, terminator) in the cell signaling process.

Function of the glucocorticoid receptor is regulated in part by its intrinsically disordered C-terminal tail. Prior to activation, the glucocorticoid receptor resides in cytosol:

glucocorticoid receptor

Intrinsic disorder in the glucocorticoid receptor not only enables multiple allosteric regulatory interactions to impact function, but also allows deployment of different surfaces of the protein to enable binding to many different sets of macromolecules, and regulation of these interactions via mRNA splicing and phosphorylation.

Combinations of alternative translation initiation and alternative mRNA splicing result in production of multiple glucocorticoid receptor isoforms from one gene. Various isoforms exhibit distinctive tissue distribution patterns and altered transcriptional regulatory profiles.

Greater than 90% of transcription factors either contain intrinsically disordered regions of proteins or are entirely intrinsically disordered. The many advantages conferred by disorder to cell signaling cascades means that:

  1. Understanding signaling required definition of roles disorder plays in each pathway;
  2. Many more examples of disordered proteins in cell signaling pathways are likely to be discovered; and
  3. More mechanisms by which disorder functions remain to be elucidated.”

https://biosignaling.biomedcentral.com/articles/10.1186/s12964-022-00821-7 “Intrinsically disordered proteins play diverse roles in cell signaling”

Cells in vivo seldom act on their own impetus. I would have liked discussion – or at least mention – of bidirectional signals between genes / cells / tissues / organs / organism / environment. This review’s topic of cell signaling pathways excluded “interactions of complex, interconnected systems spanning hierarchical levels” as explored in An environmental signaling paradigm of aging.

Vitamin K forms

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

Two papers on Vitamin K, beginning with a 2021 review:

“Vitamin K is involved in many biological processes. Menaquinones (MK) [Vitamin K2] and phylloquinone [Vitamin K1] vary in biological activity, showing different bioavailability, half-life, and transport mechanisms.

The effective dose to decrease uncarboxylated osteocalcin was six times lower for MK-7 than for MK-4. Similarly, MK-7 affected blood coagulation system at dose three to four times lower than vitamin K1.

Both vitamin K1 and MK-7 inhibited decline in bone mineral density. However, benefits for occurrence of cardiovascular diseases have been observed only for long-chain menaquinones. There are currently no guidelines for recommended doses and forms of vitamin K in prevention of osteoporosis, atherosclerosis, and other cardiovascular disorders.”

https://www.mdpi.com/2304-8158/10/12/3136/htm “Relationship between Structure and Biological Activity of Various Vitamin K Forms”

This first paper cited a 2019 meta-analysis for:

“Vitamin K2 supplementation is a preventative measure rather than an osteoporosis treatment.

Meta-analysis of various interventions for improving BMD revealed that vitamin K2 can increase lumbar spine BMD. It ranked sixth among eighteen different single or combined interventions including Ca, vitamin D, estrogen, isoflavone and exercise.

Effect size for change in bone mineral density (BMD) using forest plots. LS, lumbar spine; D, vitamin D; Est, oestrogen; Ex, exercise; K, vitamin K; Iso, isoflavone; FN, femoral neck.

urn cambridge.org id binary-alt 20211204100437-73338-optimisedImage-S0007114519002290_fig3g

Lumbar spine:

  • Ca, vitamin D, vitamin K, oestrogen, exercise, Ca + vitamin D, vitamin D + vitamin K, and vitamin D + oestrogen were associated with significantly beneficial effects relative to no treatment.
  • Ca, vitamin D, oestrogen, and Ca + vitamin D were associated with beneficial effects compared with placebo.
  • Vitamin D + vitamin K was associated with positive effect with Ca.
  • Oestrogen, vitamin D + vitamin K, and vitamin D + oestrogen were associated with beneficial effect compared with vitamin D.
  • Ca + vitamin D + exercise had a beneficial effect compared with Ca + vitamin D.
  • Ca + oestrogen, and isoflavone + exercise were related to negative effects relative to oestrogen.

Femoral neck:

  • Ca, exercise, and vitamin D + oestrogen were associated with significant beneficial intervention effects relative to no treatment.

The present study demonstrated that many interventions were valuable for improving BMD in the LS and FN of postmenopausal women. It confirmed the need for postmenopausal women to improve BMD through preventive measures such as nutrients or oestrogen.

It also confirmed that different single or combined preventions can affect BMD at different sites in different orders. This reveals to medical and health workers and postmenopausal women which methods can be selected preferentially to prevent bone loss.”

https://doi.org/10.1017/S0007114519002290 “Impact of calcium, vitamin D, vitamin K, oestrogen, isoflavone and exercise on bone mineral density for osteoporosis prevention in postmenopausal women: a network meta-analysis”

Amazingly oblivious that this freely-available second 2019 paper has been cited only by this first paper. What recent literature is more relevant to postmenopausal women’s health?

Eat broccoli sprouts for depression, Part 2

gettingwell4 4-5 stars Advanced knowledge, Acetylcholine, Amygdala, Anterior cingulate cortex, Cerebrum, Cortisol, Dopamine, Epigenetics, Glutamate, Hippocampus, Hypothalamus, Immune system, Limbic system, Memory, Neurochemicals, Serotonin, Stress , , , , ,

Here are three papers that cited last year’s Part 1. First is a 2021 rodent study investigating a microRNA’s pro-depressive effects:

“Depressive rat models were established via chronic unpredicted mild stress (CUMS) treatment. Cognitive function of rats was assessed by a series of behavioral tests.

Nrf2 CUMS

Nrf2 was weakly expressed in CUMS-treated rats, whereas Nrf2 upregulation alleviated cognitive dysfunction and brain inflammatory injury.

Nrf2 inhibited miR-17-5p expression via binding to the miR-17-5p promoter. miR-17-5p was also found to limit wolfram syndrome 1 (Wfs1) transcription.

We found that Nrf2 inhibited miR-17-5p expression and promoted Wfs1 transcription, thereby alleviating cognitive dysfunction and inflammatory injury in rats with depression-like behaviors. We didn’t investigate the role of Nrf2 in other depression models (chronic social stress model and chronic restraint stress model) and important brain regions other than hippocampus, such as prefrontal cortex and nucleus accumbens. Accordingly, other depression models and brain regions need to be designed and explored to further validate the role of Nrf2 in depression in future studies.”

https://link.springer.com/article/10.1007/s10753-021-01554-4 “Nrf2 Alleviates Cognitive Dysfunction and Brain Inflammatory Injury via Mediating Wfs1 in Rats with Depression‑Like Behaviors” (not freely available)

This study demonstrated that activating the Nrf2 pathway inhibited brain inflammation, cognitive dysfunction, and depression. Would modulating one microRNA and one gene in vivo without Nrf2 activation achieve similar results?

A 2021 review focused on the immune system’s role in depression:

“Major depressive disorder is one of the most common psychiatric illnesses. The mean age of patients with this disorder is 30.4 years, and the prevalence is twice higher in women than in men.

Activation of inflammatory pathways in the brain is considered to be an important producer of excitotoxicity and oxidative stress inducer that contributes to neuronal damage seen in the disorder. This activation is mainly due to pro-inflammatory cytokines activating the tryptophan-kynurenine (KP) pathway in microglial cells and astrocytes.

Elevated levels of cortisol exert an inhibitory feedback mechanism on its receptors in the hippocampus and hypothalamus, stopping stimulation of these structures to restore balance. When this balance is disrupted, hypercortisolemia directly stimulates extrahepatic enzyme 2,3-indolimine dioxygenase (IDO) located in various tissues (intestine, placenta, liver, and brain) and immune system macrophages and dendritic cells.

Elevation of IDO activities causes metabolism of 99% of available tryptophan in the KP pathway, substantially reducing serotonin synthesis, and producing reactive oxygen species and nitrogen radicals. The excitotoxicity generated produces tissue lesions, and activates the inflammatory response.”

https://academic.oup.com/ijnp/article/25/1/46/6415265 “Inflammatory Process and Immune System in Major Depressive Disorder”

This review highlighted that stress via cortisol and IDO may affect the brain and other parts of the body.

A 2022 review elaborated on Part 1’s findings of MeCP2 as a BDNF inhibitor:

“Methyl-CpG-binding protein 2 (MeCP2) is a transcriptional regulator that is highly abundant in the brain. It binds to methylated genomic DNA to regulate a range of physiological functions implicated in neuronal development and adult synaptic plasticity.

Ability to cope with stressors relies upon activation of the hypothalamic–pituitary–adrenal (HPA) axis. MeCP2 has been shown to contribute to early life stress-dependent epigenetic programming of genes that enhance HPA-axis activity.

We describe known functions of MeCP2 as an epigenetic regulator, and provide evidence for its role in modulating synaptic plasticity via transcriptional regulation of BDNF or other proteins involved in synaptogenesis and synaptic strength like reelin. We conclude that MeCP2 is a promising target for development of novel, more efficacious therapeutics for treatment of stress-related disorders such as depression.”

https://www.mdpi.com/2073-4409/11/4/748/htm “The Role of MeCP2 in Regulating Synaptic Plasticity in the Context of Stress and Depression”

Osprey lunch

PXL_20220221_192924474