Part 3 of Rejuvenation therapy and sulforaphane

Part 1 focused on the study’s clinical biomarkers. Part 2 highlighted its epigenetic clocks. Now we’ll look at rejuvenation of cognitive function.

Charts for this study’s most relevant human aging applications – measured by the new human-rat relative biological age clock – were in supplementary data due to combining the study’s untreated tissue samples into clock training data. Reanalyses showed:

“Using the final version of the epigenetic clocks, we find that the treatment effects become even more significant especially for the hypothalamus.”

Human-rat relative clock percentages of rejuvenation were:

  • “Blood 70.6%
  • Liver 79.4%
  • Heart 61.6%
  • Hypothalamus 20.9%”

The Discussion section addressed hypothalamus rejuvenation:

“Why does plasma fraction treatment not reduce brain epigenetic age by the same magnitude as it does the other organs? We can only begin to address this question after having first understood what epigenetic aging entails.

As it stands, our knowledge in this area remains limited, but it is nevertheless clear that:

  1. Epigenetic aging is distinct from the process of cellular senescence and telomere attrition,
  2. Several types of tissue stem cells are epigenetically younger than non-stem cells of the same tissue,
  3. A considerable number of age-related methylation sites, including some clock CpGs, are proximal to genes whose proteins are involved in the process of development,
  4. Epigenetic clocks are associated with developmental timing, and
  5. Relate to an epigenomic maintenance system.

Collectively, these features indicate that epigenetic aging is intimately associated with the process of development and homeostatic maintenance of the body post-maturity.

  • While most organs of the body turnover during the lifetime of the host, albeit at different rates, the brain appears at best to do this at a very much slower rate.
  • While most tissues harbor stem cells that are necessary for replenishment and turnover, stem cells in adult brain have only been detected in a defined and very limited area of the subventricular zone, olfactory bulb (in rats), hippocampus and hypothalamic proliferative region.

As such, if plasma fraction treatment’s rejuvenating effect is:

  • Mediated through the process of development and
  • Involves tissue stem cells

then its effect on the epigenetic age of the brain would appear to be modest, which indeed it does.

It is to be noted however, that improving brain function does not depend on neurogenesis as much as it does on synapse formation and factors such as NMDA receptors which decline in density with age.

Assessment of plasma fraction treatment on cognitive function (learning and memory). Rats were subjected to Barnes maze test – nine consecutive days of test where the time (in seconds) required by the rats to find the escape hole (latency) was recorded and plotted. The error bars depict 2 standard errors.

Within a month of plasma fraction treatment, the rats exhibited significantly reduced latency to escape, i.e., they learned and remembered better. After the second month, the treated rats began with a slightly reduced latency period compared to the untreated old rats, and once again, they learned much faster than the latter.

By the third month, it was clear that treated rats remembered the maze much better than the untreated ones even from the first day of test as their latency period was significantly reduced and by the end of the test period their latency was similar to that of the young rats. This feature was sustained and repeated in the fourth month.”

Not sure why there’s a 62-day gap between “Second month” and “Third month.” Maybe it had something to do with “First month” starting 10 days after the first treatment and “Third month” similarly starting 13 days after the second treatment?


Regarding cognitive function, a 2019 Italian paper Polyphenol Health Effects on Cardiovascular and Neurodegenerative Disorders: A Review and Meta-Analysis analyzed pathetic results of experiments with polyphenols other than broccoli sprout compounds:

“Current treatments to halt cognitive decline are limited to counteract symptoms and have a positive impact on cognition and behavior only in a transient manner, without affecting the underlying pathology.

Although some polyphenols might improve specific markers of cardiovascular risk and cognitive status, many inconsistent data are present in literature. Therefore, definitive recommendations for the use of these compounds in the prevention of cardiovascular disease and cognitive decline are currently not applicable.”


Many of us know older people who lived well past the time of good cognitive function. We see how they’re helpless and dependent. We see how others take advantage of them as they decline past the end of their healthspan.

We can make personal plans for that day, sure. But let’s also put some urgency into applying this study’s new human-rat relative biological age clock, and make:

“A step change in aging research. Although conservation of aging mechanism could be equally deduced from the existence of multiple individual clocks for other mammals (mouse, dog), the single formula of the human-rat clock that is equally applicable to both species effectively demonstrates this fact.”

Part 2 of Rejuvenation therapy and sulforaphane

A rejuvenation therapy and sulforaphane focused on the study’s clinical biomarkers and not its biological age measurements. This Part 2 curation of the study highlights its epigenetic clocks because:

“While clinical biomarkers have obvious advantages (being indicative of organ dysfunction or disease), they are neither sufficiently mechanistic nor proximal to fundamental mechanisms of aging to serve as indicators of them. It has long been recognized that epigenetic changes are one of several primary hallmarks of aging.

DNA methylation (DNAm) epigenetic clocks capture aspects of biological age. The discrepancy between DNAm age and chronological age (term as ‘epigenetic age acceleration’) is predictive of all-cause mortality. Pathologies and conditions that are associated with epigenetic age acceleration includes, but are not limited to, cognitive and physical functioning, centenarian status, Down syndrome, HIV infection, obesity, and early menopause.

The [new] human-rat clocks apply to both species. The two human-rat pan-tissue clocks are distinct, by way of measurement parameters. One estimates absolute age (in units of years), while the other estimates relative age, which is the ratio of chronological age to maximum lifespan; with values between 0 and 1. This ratio allows alignment and biologically meaningful comparison between species with very different lifespan (rat and human), which is not afforded by mere measurement of absolute age.

Relative age estimation was made using the formula: Relative age = Age / maxLifespan where the maximum lifespan for rats and humans were set to 3.8 years and 122.5 years, respectively.”

From Supplementary Table 3, old control and old treatment subjects were males 109 weeks old, 55% of their maximum lifespan (109 / 197.6). Young control subjects were males 30 weeks old, 15% of their maximum lifespan.

The money charts for this study’s human aging applications – measured by the new human-rat relative biological age clock – were buried in Supplementary Figure 12, bar plots M through P:

“Human-rat clock measure of relative age defined as age/maximum species lifespan. Each bar-plot reports the mean value and one standard error.”

From Supplementary Table 8, the percentages of rejuvenation for the above bar plots, calculated as “(100 * (1 – Old Treated / Old Control)” were:

  • “Blood 70.6%
  • Liver 79.4%
  • Heart 61.6%
  • Hypothalamus 20.9%”

Let’s return to clinical biomarkers for comparison purposes. The current study measured pro-inflammatory cytokine IL-6 blood plasma levels at every time point, but didn’t publish numbers. Bar plots and narrative were:

“Inflammation is an important response that helps protect the body, but excess inflammation especially in terms of duration of this response can have very detrimental effects instead. This occurs when inflammation fails to subside and persists indefinitely; a condition referred to as chronic inflammation, which for reasons not well-understood, increases with age and is associated with a multitude of conditions and pathologies.

The levels of two of the most reliable and common biomarkers of chronic inflammation, interleukin 6 (IL-6) and tumor necrosis factor α (TNF-α), are found to be considerably higher in old rats, and these were very rapidly diminished, within days by plasma fraction treatment, to comparable levels with those of young rats. This was especially stark with IL-6.

In time, the levels of these inflammatory factors began to rise gradually, but they were once again very effectively reduced following the second administration of the plasma fraction on the 95th day.”

Let’s compare the above IL-6 graphic with IL-6 concentration improvements of our 2018 model clinical trial, Effects of long-term consumption of broccoli sprouts on inflammatory markers in overweight subjects, calculated as (100 * (1 – Day _ mean / Day 0 mean):

Mean pg/ml | % improvement | Period | Broccoli sprout consumption

  • 4.594 | 0% | Day 0 | “One week before the beginning of the intervention period, subjects were asked to avoid the consumption of Brassica vegetables (broccoli, radish, cauliflower, Brussel sprouts, mustards, among others) and their derived products.”
  • 1.748 | 62.0% | Day 0 to 70 | Subjects ate 30 g raw broccoli sprouts every day, and stopped eating them after Day 70.
  • 0.896 | 80.5% | Day 0 to 90 | “After the intervention period, a follow-up recovery period for all subjects continued for another 90 days with no ingestion of broccoli sprouts.”
  • 2.170 | 52.8% | Day 0 to 160 | Subjects had not eaten broccoli sprouts after Day 70.

Results between the studies were similar in that:

  1. IL-6 levels improved during early treatments through rat Day 8 and human Day 70, respectively.
  2. IL-6 levels continued decreasing shortly after treatments for 7 days (through rat Day 15) and 20 days (through human Day 90), respectively.
  3. IL-6 levels rose after rat Day 15 and human Day 90, respectively, but were still significantly below Day 0 values at rat Day 95 and human Day 160.

The current study measured Nrf2 but didn’t publish numbers. Bar plots and narrative were:

“The reduction of these inflammation markers is consistent with the profile of the nuclear factor erythroid 2-like 2 protein (Nrf2), which plays a major role in resolving inflammation, in part by inhibiting the expression of IL-6 and TNF-α. Nrf2 also induces the expression of antioxidants that neutralizes ROS [reactive oxygen species], which is also a significant feature in inflammation.”

A PubMed search on “nrf2 sulforaphane human” didn’t turn up relevant 2020 human in vivo studies. I disregarded reviews, cancer studies, disproven hypotheses, and other compounds listed in the below graphic.

I won’t repeat the entire Nrf2 section from the Part 1 curation, just one graphic and paragraph:

It [sulforaphane] is not only a potent Nrf2 inducer but also highly bioavailable [around 80%], so that modest practical doses can produce significant clinical responses. Other Nrf2 activators [shown in the above image] not only lack potency but also lack the bioavailability to be considered as significant intracellular Nrf2 activators.”


As noted in Reviewing clinical trials of broccoli sprouts and their compounds, there are no sulforaphane clinical trials that also use epigenetic clocks. Broccoli sprouts and their compounds’ effects on human aging is an area that hasn’t drawn attention and funding.

What are the effects that broccoli sprouts and their compounds may have on human aging? With this new human-rat relative biological age clock, researchers can get reliable answers from rat studies, with human clinical trials needed only to confirm those findings!

As rejuvenation research continues, what could people do easily, cheaply, and today for our long-term selves? Don’t know about the hypothalamus, but our blood, liver, and heart biological ages may decrease as we reduce inflammation and oxidative stress by eating broccoli sprouts.

I’m at a similar relative percentage of species maximum lifespan as were the study’s old subjects. It’s my choice as to what my healthspan will be.

There isn’t evidence today to definitively say that changing my inflammatory phenotype with broccoli sprouts has had / will have rejuvenation effects on biological ages of my cells, organs, and body. But if eating broccoli sprouts every day not only reduces chronic inflammation and oxidative stress as expected, but also makes me younger, I could probably learn to live with that. 🙂

Continued with Part 3 of Rejuvenation therapy and sulforaphane.

A rejuvenation therapy and sulforaphane

The founder of the epigenetic clock methodology with the coauthor of Aging as an unintended consequence released a 2020 rodent study “Reversing age: dual species measurement of epigenetic age with a single clock” at https://www.biorxiv.org/content/10.1101/2020.05.07.082917v1.full.pdf:

“We employed six clocks to investigate the rejuvenation effects of a plasma fraction treatment in different rat tissues. Two of these epigenetic clocks apply to both humans and rats.

The treatment more than halved the epigenetic ages of blood, heart, and liver tissue. A less pronounced, but statistically significant, rejuvenation effect could be observed in the hypothalamus.

The treatment was accompanied by progressive improvement in the function of these organs as ascertained through numerous biochemical/physiological biomarkers and behavioral responses to assess cognitive functions. Cellular senescence, which is not associated with epigenetic aging, was also considerably reduced in vital organs.

Plasma fraction treatment consists of two series of intravenous injections of plasma fraction. Rats were injected four times on alternate days for 8 days. A second identical series of injections were administered 95 days later. In its entirety, the experiment lasted 155 days.

Overall, this study demonstrates that a plasma-derived treatment markedly reverses aging according to epigenetic clocks and benchmark biomarkers of aging.”

The study hasn’t been peer reviewed, so can’t be viewed yet as conclusive. Given that researchers’ single-most valuable asset is their reputations, though, will the findings have major revisions?


I was alerted to the study by Josh Mitteldorf’s blog post Age Reduction Breakthrough, who did his usual excellent curation:

“Most of the explosion in aging research (and virtually all the venture capital startups) are looking to treat aging at the cellular level. Their paradigm is that aging is an accumulation of molecular damage, and they see their job as engineering of appropriate repair mechanisms.

The truth, as Katcher [the lead lab researcher] understands it, is that, to a large extent, aging is coordinated system-wide via signal molecules in the blood. The problem is that there are thousands of constituents represented in tiny concentrations in blood plasma, but conveying messages that cells read. Which of these are responsible for aging?

The two-species clock[s] was [were] a significant innovation, a first bridge for translating results from an animal model into their probable equivalent in humans. Besides the methylation clock[s], the paper presents evidence of rejuvenation by many other measures. For example:

  • IL-6, a marker of inflammation, was restored to low youthful levels;
  • Glutathione (GSH), superoxide dismutase (SOD), and other antioxidants were restored to higher youthful levels;
  • In tests of cognitive function (Barnes maze), treated rats scored better than old rats, but not as well as young rats.;
  • Blood triglycerides were brought down to youthful levels;
  • HDL cholesterol rose to youthful levels; and
  • Blood glucose fell toward youthful levels.

These results bring together three threads that have been gaining credibility over the last decade. Mutually reinforcing, the three have a strength that none of them could offer separately.

  1. The root cause of aging is epigenetic progression = changes in gene expression over a lifetime.
  2. Methylation patterns in nuclear DNA are not merely a marker of aging, but its primary source. Thus aging can be reversed by reprogramming DNA methylation.
  3. Information about the body’s age state is transmitted system-wide via signal molecules in the blood. Locally, tissues respond to these signals and adopt a young or an old cellular phenotype as they are directed.”

Several of these aging measurements are also positively affected by sulforaphane. Using Sulforaphane: Its “Coming of Age” as a Clinically Relevant Nutraceutical in the Prevention and Treatment of Chronic Disease as a reference:

1. “Chronic inflammation”

“Antioxidants in general and glutathione in particular can be depleted rapidly under conditions of oxidative stress, and this can signal inflammatory pathways associated with NF-κB. SFN [sulforaphane] has been shown to inhibit NF-κB in endothelial cells.

Two key inflammatory cytokines were measured at four time points in forty healthy overweight people [our model clinical trial, Effects of long-term consumption of broccoli sprouts on inflammatory markers in overweight subjects]. The levels of both interleukin-6 (Il-6) and C-reactive protein (CRP) declined over the 70 days during which the sprouts were ingested. These biomarkers were measured again at day 90, wherein it was found that Il-6 continued to decline, whereas CRP climbed again. When the final measurement was taken at day 160, CRP, although climbing, had not returned to its baseline value. Il-6 remained significantly below the baseline level at day 160.”

OMCL2019-2716870.010

2. “Oxidative stress”

“As a mediator for amplification of the mammalian defence system against various stressors, Nrf2 [nuclear factor erythroid 2-related factor 2] sits at the interface between our prior understanding of oxidative stress and the endogenous mechanisms cells use to deal with it. Diseases known to be underpinned by oxidative stress are proving to be more responsive to amplification of cellular defences via Nrf2 activation than by administration of direct-acting antioxidant supplements.

SFN, with absolute bioavailability of around 80%, [is] capable of increasing several endogenous antioxidant compounds via the transcription factor, Nrf2.

Nrf2 is ubiquitously expressed with the highest concentrations (in descending order) in the kidney, muscle, lung, heart, liver, and brain. Nrf2 was shown to prevent endothelial cells from exhibiting a proinflammatory state. Nrf2 is required for protection against glucose-induced oxidative stress and cardiomyopathy in the heart.

Well in excess of 500 genes have been identified as being activated by SFN via the Nrf2/ARE [Antioxidant Response Element] pathway, and it is likely that this underestimates the number as others are being discovered. Of the available SFN clinical trials associated with genes induced via Nrf2 activation, many demonstrate a linear dose-response. More recently, it has become apparent that SFN can behave hormetically with different effects responsive to different doses.

It [sulforaphane] is not only a potent Nrf2 inducer but also highly bioavailable so that modest practical doses can produce significant clinical responses. Other Nrf2 activators [shown in the above image] not only lack potency but also lack the bioavailability to be considered as significant intracellular Nrf2 activators.”


The study’s most relentlessly questioned, scrutinized, and criticized findings may be the two new epigenetic clocks that apply to both humans and rats. The researchers invited other researchers to validate these clocks because:

“If validated, this would be a step change in aging research. Although conservation of aging mechanism could be equally deduced from the existence of multiple individual clocks for other mammals (mouse, dog), the single formula of the human-rat clock that is equally applicable to both species effectively demonstrates this fact.”

The commonalities of this study with efforts to change my inflammatory phenotype with broccoli sprouts were summarized in the Discussion section:

“Apart from rejuvenating the vital organs of the treated rats, plasma fraction also impacted two fundamental physiological processes that underlie a great number of pathologies, namely oxidative stress and inflammation. Within a week of treatment, the markers of chronic inflammation (IL-6 and TNF-α) were significantly reduced and remained low throughout the entire experiment.

Likewise, markers of oxidative stress in brain, heart, lung and liver, which were very much higher in control old rats, were at the end of the experimental period, indistinguishable between plasma fraction-treated old rats and young ones. Concomitant with this drastic reduction in oxidative stress was the augmented levels of antioxidants (GSH, Catalase and SOD) in these tissues, indicating that modulating the levels of ROS [reactive oxygen species] to that of youthful rats is at least one way by which plasma fraction suppresses oxidative stress. It remains to be ascertained whether the rate of ROS generation is also reduced.

The levels of Nrf2, a transcription factor that impacts on oxidative stress, as well as inflammation, were raised by plasma fraction treatment of old rats to those of the young ones, indicating yet another level by which this treatment modulates these two critical processes. Collectively, these results show that plasma fraction treatment impacts not only the overt performances of organs, but also the underlying physiological processes that are pivotal for optimal organ function and health.”

Great stuff, huh? Are you ready to change your phenotype?

Continued with Part 2 of Rejuvenation therapy and sulforaphane.

The epigenetics of perinatal stress

This 2019 McGill review discussed long-lasting effects of perinatal stress:

“Epigenetic processes are involved in embedding the impact of early-life experience in the genome and mediating between social environments and later behavioral phenotypes. Since these phenotypes are apparent a long time after the early experience, the changes in gene expression programming must be stable.

Although loss of methylation in a promoter is necessary for expression, it is not sufficient. Demethylation removes a barrier for expression, but expression might be realized at the right time or context when the needed factors or signals are present.

DNA methylation anticipates future transcriptional response to triggers. Comparing steady-state expression with DNA methylation does not capture the full meaning and scope of the regulatory roles of differential methylation.

A model for epigenetic programming by early life stress:

  1. Perinatal stress perceived by the brain triggers release of glucocorticoids (GC) from the adrenal in the mother prenatally or the newborn postnatally.
  2. GC activate nuclear glucocorticoid receptors across the body, which epigenetically program (demethylate) genes that are targets of GR in brain and white blood cells (WBC).
  3. The demethylation events are insufficient for activation of these genes. A brain specific factor (TF) is required for expression and will activate low expression of the gene in the brain but not in blood.
  4. During adulthood a stressful event transiently triggers a very high level of expression of the GR regulated gene specifically in the brain.

Horizontal arrow, transcription; circles, CpG sites; CH3 in circles, methylated sites; empty circles, unmethylated CpG sites; horizon[t]al curved lines, mRNA.”

Points discussed in the review:

  • “Epigenetic marks are laid down and maintained by enzymes that either add or remove epigenetic modifications and are therefore potentially reversible in contrast to genetic changes.
  • The response to early life stress and maternal behavior is also not limited to the brain and involves at least the immune system as well.
  • The placenta is also impacted by maternal social experience and early life stress.
  • Most studies are limited to peripheral tissues such as saliva and white blood cells, and the relevance to brain physiology and pathology is uncertain.
  • The low absolute differences in methylation seen in most human behavioral EWAS raise questions about their biological significance.

  • Although post-mortem studies examine epigenetic programming in physiologically relevant tissues, they represent only a final and single stage that does not capture the dynamic evolution of environments and epigenetic programming in living humans.”

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6952743/ “The epigenetics of perinatal stress”


Other reviewers try to ignore the times when we were all fetuses and newborns. For example, in the same journal issue was a Boston review of PTSD that didn’t mention anything about the earliest times of human lives! Those reviewers speculated around this obvious gap on their way to being paid by NIH.

Why would researchers ignore perinatal stress events that prime humans for later-life PTSD? Stress generally has a greater impact on fetuses and newborns than even infants, and a greater impact on infants than adults.

Clearing out the 2019 queue of interesting papers

I’m clearing out the below queue of 27 studies and reviews I’ve partially read this year but haven’t taken the time to curate. I have a pesky full-time job that demands my presence elsewhere during the day. :-\

Should I add any of these back in? Let’s be ready for the next decade!


Early life

https://link.springer.com/article/10.1007/s12035-018-1328-x “Early Behavioral Alterations and Increased Expression of Endogenous Retroviruses Are Inherited Across Generations in Mice Prenatally Exposed to Valproic Acid” (not freely available)

https://www.sciencedirect.com/science/article/pii/S0166432818309392 “Consolidation of an aversive taste memory requires two rounds of transcriptional and epigenetic regulation in the insular cortex” (not freely available)

https://www.nature.com/articles/s41380-018-0265-4 “Intergenerational transmission of depression: clinical observations and molecular mechanisms” (not freely available)

mother

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6454089/ “Epigenomics and Transcriptomics in the Prediction and Diagnosis of Childhood Asthma: Are We There Yet?”

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6628997/Placental epigenetic clocks: estimating gestational age using placental DNA methylation levels”

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6770436/ “Mismatched Prenatal and Postnatal Maternal Depressive Symptoms and Child Behaviours: A Sex-Dependent Role for NR3C1 DNA Methylation in the Wirral Child Health and Development Study”

https://www.sciencedirect.com/science/article/pii/S0889159119306440 “Environmental influences on placental programming and offspring outcomes following maternal immune activation”

https://academic.oup.com/mutage/article-abstract/34/4/315/5581970 “5-Hydroxymethylcytosine in cord blood and associations of DNA methylation with sex in newborns” (not freely available)

https://physoc.onlinelibrary.wiley.com/doi/full/10.1113/JP278270 “Paternal diet impairs F1 and F2 offspring vascular function through sperm and seminal plasma specific mechanisms in mice”

https://onlinelibrary.wiley.com/doi/full/10.1111/nmo.13751 “Sex differences in the epigenetic regulation of chronic visceral pain following unpredictable early life stress” (not freely available)

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6811979/ “Genome-wide DNA methylation data from adult brain following prenatal immune activation and dietary intervention”

https://link.springer.com/article/10.1007/s00702-019-02048-2miRNAs in depression vulnerability and resilience: novel targets for preventive strategies”


Later life

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6543991/ “Effect of Flywheel Resistance Training on Balance Performance in Older Adults. A Randomized Controlled Trial”

https://www.mdpi.com/2411-5142/4/3/61/htm “Eccentric Overload Flywheel Training in Older Adults”

https://www.nature.com/articles/s41577-019-0151-6 “Epigenetic regulation of the innate immune response to infection” (not freely available)

https://link.springer.com/chapter/10.1007/978-981-13-6123-4_1 “Hair Cell Regeneration” (not freely available)

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6422915/Histone Modifications as an Intersection Between Diet and Longevity”

https://www.sciencedirect.com/science/article/abs/pii/S0306453019300733 “Serotonin transporter gene methylation predicts long-term cortisol concentrations in hair” (not freely available)

https://www.sciencedirect.com/science/article/abs/pii/S0047637419300338 “Frailty biomarkers in humans and rodents: Current approaches and future advances” (not freely available)

https://onlinelibrary.wiley.com/doi/full/10.1111/pcn.12901 “Neural mechanisms underlying adaptive and maladaptive consequences of stress: Roles of dopaminergic and inflammatory responses

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6627480/ “In Search of Panacea—Review of Recent Studies Concerning Nature-Derived Anticancer Agents”

https://www.sciencedirect.com/science/article/abs/pii/S0028390819303363 “Reversal of oxycodone conditioned place preference by oxytocin: Promoting global DNA methylation in the hippocampus” (not freely available)

https://www.futuremedicine.com/doi/10.2217/epi-2019-0102 “Different epigenetic clocks reflect distinct pathophysiological features of multiple sclerosis”

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6834159/ “The Beige Adipocyte as a Therapy for Metabolic Diseases”

https://www.sciencedirect.com/science/article/abs/pii/S8756328219304077 “Bone adaptation: safety factors and load predictability in shaping skeletal form” (not freely available)

https://www.nature.com/articles/s41380-019-0549-3 “Successful treatment of post-traumatic stress disorder reverses DNA methylation marks” (not freely available)

https://www.sciencedirect.com/science/article/abs/pii/S0166223619301821 “Editing the Epigenome to Tackle Brain Disorders” (not freely available)

Using oxytocin receptor gene methylation to pursue an agenda

A pair of 2019 Virginia studies involved human mother/infant subjects:

“We show that OXTRm [oxytocin receptor gene DNA methylation] in infancy and its change is predicted by maternal engagement and reflective of behavioral temperament.”

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6795517 “Epigenetic dynamics in infancy and the impact of maternal engagement”

“Infants with higher OXTRm show enhanced responses to anger and fear and attenuated responses to happiness in right inferior frontal cortex, a region implicated in emotion processing through action-perception coupling.

Infant fNIRS [functional near-infrared spectroscopy] is limited to measuring responses from cerebral cortex..it is unknown whether OXTR is expressed in the cerebral cortex during prenatal and early postnatal human brain development.”

https://www.sciencedirect.com/science/article/pii/S187892931830207X “Epigenetic modification of the oxytocin receptor gene is associated with emotion processing in the infant brain”


Both studies had weak disclosures of limitations on their findings’ relevance and significance. The largest non-disclosed contrary finding was from the 2015 Early-life epigenetic regulation of the oxytocin receptor gene:

These results suggest that:

  • Blood Oxtr DNA methylation may reflect early experience of maternal care, and
  • Oxtr methylation across tissues is highly concordant for specific CpGs, but
  • Inferences across tissues are not supported for individual variation in Oxtr methylation.

This rat study found that blood OXTR methylation of 25 CpG sites couldn’t accurately predict the same 25 CpG sites’ OXTR methylation in each subject’s hippocampus, hypothalamus, and striatum (which includes the nucleus accumbens) brain areas. Without significant effects in these limbic system structures, there couldn’t be any associated behavioral effects.

But CpG site associations and correlations were deemed good in the two current studies because they cited:

“Recent work in prairie voles has found that both brain- and blood-derived OXTRm levels at these sites are negatively associated with gene expression in the brain and highly correlated with each other.”

https://www.sciencedirect.com/science/article/pii/S0306453018306103 “Early nurture epigenetically tunes the oxytocin receptor”

The 2018 prairie vole study – which included several of the same researchers as the two current studies – found four nucleus accumbens CpG sites that had high correlations to humans. Discarding one of these CpG sites allowed their statistics package to make a four-decimal place finding:

“The methylation state of the blood was also associated with the level of transcription in the brain at three of the four CpG sites..whole blood was capable of explaining 94.92% of the variance in Oxtr DNA methylation and 18.20% of the variance in Oxtr expression.”

Few limitations on the prairie vole study findings were disclosed. Like the two current studies, there wasn’t a limitation section that placed research findings into suitable contexts. So readers didn’t know researcher viewpoints on items such as:

  • What additional information showed that 3 of the 30+ million human CpGs accurately predicted specific brain OXTR methylation and expression from saliva OXTR methylation?
  • What additional information demonstrated how “measuring responses from cerebral cortex” although “it is unknown whether OXTR is expressed in the cerebral cortex” provided detailed and dependable estimates of limbic system CpG site OXTR methylation and expression?
  • Was the above 25-CpG study evidence considered?

Further contrast these three studies with a typical, four-point, 285-word limitation section of a study like Prenatal stress heightened adult chronic pain. The word “limit” appeared 6 times in that pain study, 3 times in the current fNIRS study, and 0 times in the current maternal engagement and cited prairie vole studies.

Frank interpretations of one’s own study findings to acknowledge limitations is one way researchers can address items upfront that will be questioned anyway. Such analyses also indicate a goal to advance science.

Prenatal stress heightened adult chronic pain

This 2019 McGill rodent study found:

Prenatal stress exacerbates pain after injury. Analysis of mRNA expression of genes related to epigenetic regulation and stress responses in the frontal cortex and hippocampus, brain structures implicated in chronic pain, showed distinct sex and region-specific patterns of dysregulation.

In general, mRNA expression was most frequently altered in the male hippocampus and effects of prenatal stress were more prevalent than effects of nerve injury. Recent studies investigating chronic pain-related pathology in the hippocampus in humans and in rodent models demonstrate functional abnormalities in the hippocampus, changes in associated behavior, and decreases in adult hippocampal neurogenesis.

The change in expression of epigenetic- and stress-related genes is not a consequence of nerve injury but rather precedes nerve injury, consistent with the hypothesis that it might play a causal role in modulating the phenotypic response to nerve injury. These findings demonstrate the impact of prenatal stress on behavioral sensitivity to a painful injury.

Decreased frontal mRNA expression of BDNF and BDNF IV in male offspring following neuropathic pain or prenatal stress respectively. Relative mRNA expression of other stress-related genes (GR17, FKBP5) and epigenetic-related genes (DNMTs, TETs, HDACs, MBDs, MeCP2) in male offspring.

A drastic decrease in expression of HDAC1 was observed in all groups compared to sham-control animals. CCI: chronic constriction injury.”


The study’s design was similar to the PRS (prenatal restraint stress) model, except that the PRS procedure covered gestational days 11 to 21 (birth):

“Prenatal stress was induced on Embryonic days 13 to 17 by restraining the pregnant dams in transparent cylinder with 5 mm water, under bright light exposure, 3 times per day for 45 min.”

None of the French, Italian, and Swiss PRS studies were cited.

The limitation section included:

  1. “Although our study shows significant changes in expression of epigenetic enzymes, it didn’t examine the impact of these changes on genes that are epigenetically regulated by this machinery or their involvement in intensifying pain responses.
  2. The current study is limited by the focus on changes in gene expression which do not necessarily correlate with changes in protein expression.
  3. Another limitation of this study is the inability to distinguish the direct effects of stress in utero vs. changes in the dam’s maternal behavior due to stress during pregnancy; cross-fostering studies are needed to address this issue.
  4. Functional experiments that involve up and down regulation of epigenetic enzymes in specific brain regions are required to establish a causal role for these processes in chronic pain.”

What do you think about possible human applicability of this study’s “effects of prenatal stress were more prevalent than effects of nerve injury” finding?

Are there any professional frameworks that instruct trainees to recognize that if a person’s mother was stressed while pregnant, their prenatal experiences could cause more prevalent biological and behavioral effects than a recent injury?

https://www.sciencedirect.com/science/article/pii/S0166432819315219 “Prenatal maternal stress is associated with increased sensitivity to neuropathic pain and sex-specific changes in supraspinal mRNA expression of epigenetic- and stress-related genes in adulthood” (not freely available)

An epigenetic clock review by committee

This 2019 worldwide review of epigenetic clocks was a semi-anonymous mishmash of opinions, facts, hypotheses, unwarranted extrapolations, and beliefs. The diversity of viewpoints among the 21 coauthors wasn’t evident.

1. Citations of the coauthors’ works seemed excessive, and they apologized for omissions. However:

  • Challenge 5 was titled “Single-cell analysis of aging changes and disease” and
  • Table 1 “Major biological and analytic issues with epigenetic DNA methylation clocks” had single-cell analysis as the Proposed solution to five Significant issues.

Yet studies such as High-Resolution Single-Cell DNA Methylation Measurements Reveal Epigenetically Distinct Hematopoietic Stem Cell Subpopulations were unmentioned.

2. Some coauthors semi-anonymously expressed faith that using current flawed methodologies in the future – only more thoroughly, with newer equipment, etc. – would yield better results. If the 21 coauthors were asked their viewpoints of Proposed solutions to the top three Significant issues of epigenetic clocks, what would they emphasize when quoted?

3. Techniques were praised:

“Given the precision with which DNA methylation clock age can be estimated and evolving measures of biological, phenotype-, and disease-related age (e.g., PhenoAge, GrimAge)..”

Exactly why these techniques have at times produced inexplicable results wasn’t examined, though. Two examples:

  • In Reversal of aging and immunosenescent trends, the Levine PhenoAge methodology estimated that the 51-65 year old subjects’ biological ages at the beginning of the study averaged 17.5 years less than their chronological age. Comparing that to the Horvath average biological age of 3.95 years less raised the question: exactly why did PhenoAge show such a large difference?
  • The paper mentioned the GrimAge methodology findings about “smoking-related changes.” But it didn’t explain why the GrimAge methylation findings most closely associated with smoking history also accurately predicted future disease risk with non-smokers.

Eluding explanations for these types of findings didn’t help build confidence in the methodologies.

4. A more readable approach to review by committee could have coauthors – in at least one section – answer discussion questions, as Reversing epigenetic T cell exhaustion did with 18 experts.

https://genomebiology.biomedcentral.com/articles/10.1186/s13059-019-1824-y “DNA methylation aging clocks: challenges and recommendations”

A review of fetal adverse events

This 2019 Australian review subject was fetal adversities:

“Adversity during the perinatal period is a significant risk factor for the development of neurodevelopmental disorders long after the causative event. Despite stemming from a variety of causes, perinatal compromise appears to have similar effects on the developing brain, thereby resulting in behavioural disorders of a similar nature.

These behavioural disorders occur in a sex‐dependent manner, with males affected more by externalizing behaviours such as attention deficit hyperactivity disorder (ADHD) and females by internalizing behaviours such as anxiety. The term ‘perinatal compromise’ serves as an umbrella term for intrauterine growth restriction, maternal immune activation, prenatal stress, early life stress, premature birth, placental dysfunction, and perinatal hypoxia.

The above conditions are associated with imbalanced excitatory-inhibitory pathways resulting from reduced GABAergic signalling. Methylation of the GAD1/GAD67 gene, which encodes the key glutamate‐to‐GABA synthesizing enzyme Glutamate Decarboxylase 1, resulting in increased levels of glutamate is one epigenetic mechanism that may account for a tendency towards excitation in disorders such as ADHD.

The posterior cerebellum’s role in higher executive functioning is becoming well established due to its connections with the prefrontal cortex, association cortices, and limbic system. It is now suggested that disruptions to cerebellar development, which can occur due to late gestation compromises such as preterm birth, can have a major impact on the region of the brain to which it projects.

Activation of the maternal hypothalamic-pituitary adrenal (HPA) axis and placental protection. Psychological stress is perceived by the maternal HPA axis, which stimulates cortisol release from the maternal adrenal gland.

High levels of maternal cortisol are normally prevented from reaching the fetus by the 11β-hydroxysteroid dehydrogenase 2 (HSD11B2) enzyme, which converts cortisol to the much less active cortisone. Under conditions of high maternal stress, this protective mechanism can be overwhelmed, with the gene encoding the enzyme becoming methylated, which reduces its expression allowing cortisol to cross the placenta and reach the fetus.”


The reviewers extrapolated many animal study findings to humans, although most of their own work was with guinea pigs. The “suggest” and “may” qualifiers were used often – 22 and 37 times, respectively. More frequent use of the “appears,” “hypothesize,” “propose,” and “possible” terms was justified.

As a result, many reviewed items such as the above graphic and caption should be viewed as hypothetical for humans rather than reflecting solid evidence from quality human studies.

The reviewers focused on the prenatal (before birth) period more than the perinatal (last trimester of pregnancy to one month after birth) period. There were fewer mentions of birth and early infancy adversities.

https://onlinelibrary.wiley.com/doi/abs/10.1111/jne.12814 “Perinatal compromise contributes to programming of GABAergic and Glutamatergic systems leading to long-term effects on offspring behaviour” (not freely available)

A drug that countered effects of a traumatizing mother

This 2019 US rodent study concerned transmitting poor maternal care to the next generation:

“The quality of parental care received during development profoundly influences an individual’s phenotype, including that of maternal behavior. Infant experiences with a caregiver have lifelong behavioral consequences.

Maternal behavior is a complex behavior requiring the recruitment of multiple brain regions including the nucleus accumbens, bed nucleus of the stria terminalis, ventral tegmental area, prefrontal cortex, amygdala, and medial preoptic area. Dysregulation within this circuitry can lead to altered or impaired maternal responsiveness.

We administered zebularine, a drug known to alter DNA methylation, to dams exposed during infancy to the scarcity-adversity model of low nesting resources, and then characterized the quality of their care towards their offspring.

  1. We replicate that dams with a history of maltreatment mistreat their own offspring.
  2. We show that maltreated-dams treated with zebularine exhibit lower levels of adverse care toward their offspring.
  3. We show that administration of zebularine in control dams (history of nurturing care) enhances levels of adverse care.
  4. We show altered methylation and gene expression in maltreated dams normalized by zebularine.

These findings lend support to the hypothesis that epigenetic alterations resulting from maltreatment causally relate to behavioral outcomes.”

“Maternal behavior is an intergenerational behavior. It is important to establish the neurobiological underpinnings of aberrant maternal behavior and explore treatments that can improve maternal behavior to prevent the perpetuation of poor maternal care across generations.”


The study authors demonstrated intergenerational epigenetic effects, and missed an opportunity to also investigate transgenerational epigenetically inherited effects. They cited reference 60 for the first part of the above quotation, but the cited reviewer misused the transgenerational term by applying it to grand-offspring instead of the great-grand-offspring.

There were resources available to replicate the study authors’ previous findings, which didn’t show anything new. Why not use such resources to uncover evidence even more applicable to humans by extending experiments to great-grand-offspring that would have no potential germline exposure to the initial damaging cause?

Could a study design similar to A limited study of parental transmission of anxiety/stress-reactive traits have been integrated? That study’s thorough removal of parental behavior would be an outstanding methodology to confirm by falsifiability whether parental behavior is both an intergenerational and a transgenerational epigenetic inheritance mechanism.

Rodent great-grand-offspring can be studied in < 9 months. It takes > 50 years for human studies to reach the great-grand-offspring transgenerational generation.

  • Why not attempt to “prevent the perpetuation of poor maternal care across generations?”
  • Isn’t it a plausible hypothesis that humans “with a history of maltreatment mistreat their own offspring?”
  • Isn’t it worth the extra effort to extend animal research to investigate this unfortunate chain?

https://www.nature.com/articles/s41598-019-46539-4 “Pharmacological manipulation of DNA methylation normalizes maternal behavior, DNA methylation, and gene expression in dams with a history of maltreatment”