The principal way science advances is through the principle Einstein expressed as:
“No amount of experimentation can ever prove me right; a single experiment can prove me wrong.”
Members of the scientific community and of the public should be satisfied that the scientific process is working well when hypotheses are discarded due to nonconfirming evidence. Researchers should strive to develop evidence that rejects paradigms, and be lauded for their efforts.
The commentators’ dismissive tone was set in the opening paragraph:
“Is early exposure to adversity associated with a genetic or an epigenetic signature? At first glance, two articles in this issue -..and the other from Marzi et al., who measured genome-wide DNA methylation in a prospective twin cohort assessed at age 18 – appear to say that it is not.”
The two commentators, one of whom was a coauthor of Manufacturing PTSD evidence with machine learning, went on to protect their territory. Never mind the two studies’ advancement of science that didn’t coincide with the commentators’ vested interests.
My main concern with the study was that although the children had been studied at ages 5, 7, 10, 12, and 18, the parents had never been similarly evaluated! The researchers passed up an opportunity to develop the parents as a F0 generation for understanding possible human transgenerational inherited epigenetic causes and effects.
The study focused on the children’s intergenerational epigenetic effects. However, animal studies have often demonstrated transgenerational effects that skip over the F1 generation children!
This 2018 Loma Linda review subject was gestational hypoxia:
“Of all the stresses to which the fetus and newborn infant are subjected, perhaps the most important and clinically relevant is that of hypoxia. This review explores the impact of gestational hypoxia on maternal health and fetal development, and epigenetic mechanisms of developmental plasticity with emphasis on the uteroplacental circulation, heart development, cerebral circulation, pulmonary development, and the hypothalamic-pituitary-adrenal axis and adipose tissue.
An understanding of the specific hypoxia-induced environmental and epigenetic adaptations linked to specific organ systems will enhance the development of target-specific inhibition of DNA methylation, histone modifications, and noncoding RNAs that underlie hypoxia-induced phenotypicprogramming of disease vulnerability later in life.
A potential stumbling block to these efforts, however, relates to timing of the intervention. The greatest potential effect would be accomplished at the critical period in development for which the genomic plasticity is at its peak, thus ameliorating the influence of hypoxia or other stressors.
With future developments, it may even become possible to intervene before conception, before the genetic determinants of the risk of developing programmed disease are established.”
Table 3 “Antenatal hypoxia and developmental plasticity” column titles were Species | Offspring Phenotypes of Disorders and Diseases | Reference Nos.
This review was really an ebook, with 94 pages and 1,172 citations in the pdf file. As I did with Faith-tainted epigenetics, I read it with caution toward recognizing the influence of the sponsor’s biases, and any directed narrative that ignored evidence contradicting the narrative, and any storytelling.
One review topic that was misconstrued was transgenerational epigenetic inheritance of hypoxic effects. The “transgenerational” term was used inappropriately by several of the citations, and no cited study provided evidence for gestational hypoxic effects through the F2 grandchild and F3 great-grandchild generations.
“One substance that fetuses are frequently exposed to is caffeine, which is a non-selective adenosine receptor antagonist. We discovered that in utero alteration in adenosine action leads to adverse effects on embryonic and adult murine hearts. We find that cardiac A1ARs [a type of adenosine receptor] protect the embryo from in utero hypoxic stress, a condition that causes an increase in adenosine levels.
After birth in mice, we observed that in utero caffeine exposure leads to abnormal cardiac function and morphology in adults, including an impaired response to β-adrenergic stimulation. Recently, we observed that in utero caffeine exposure induces transgenerational effects on cardiac morphology, function, and gene expression.”
Why was this review and its studies omitted? It was on target for both gestational hypoxia and transgenerational epigenetic inheritance of hypoxic effects!
It was alright to review smoking, cocaine, methamphetamine, etc., but the most prevalent drug addiction – caffeine – couldn’t be a review topic?
The Loma Linda review covered a lot, but I had a quick trigger due to the sponsor’s bias. I started to lose “faith” in the reviewers after reading the citation for the review’s last sentence that didn’t support the statement.
My “faith” disappeared after not understanding why a few topics were misconstrued and omitted. Why do researchers and sponsors ignore, misrepresent, and not continue experiments through the F3 generation to produce evidence for and against transgenerational epigenetic inheritance? Where was the will to follow evidence trails regardless of socially acceptable beverage norms?
The review acquired the taint of storytelling with the reviewers’ assertion:
“..timing of the intervention. The greatest potential effect would be accomplished at the critical period in development for which the genomic plasticity is at its peak, thus ameliorating the influence of hypoxia or other stressors.”
Contradictory evidence was in the omitted caffeine study’s graphic above which described two gestational periods where an “intervention” had opposite effects, all of which were harmful to the current fetus’ development and/or to following generations. Widening the PubMed link’s search parameters to “caffeine hypoxia” and “caffeine pregnancy” returned links to human early life studies that used caffeine in interventions, ignoring possible adverse effects on future generations.
This is my final curation of any paper sponsored by this institution.
This 2018 Alabama rodent study investigated the epigenetic effects on developing breast cancer of timing a sulforaphane-based broccoli sprouts diet. Timing of the diet was as follows:
Conception through weaning (postnatal day 28), named the Prenatal/maternal BSp (broccoli sprouts) treatment (what the mothers ate starting when they were adults at 12 weeks until their pups were weaned; the pups were never on a broccoli sprouts diet);
Postnatal day 28 through the termination of the experiment, named the Postnatal early-life BSp treatment (what the offspring ate starting at 4 weeks; the mothers were never on a broccoli sprouts diet); and
Postnatal day 56 through the termination of the experiment, named the Postnatal adult BSp treatment (what the offspring ate starting when they were adults at 8 weeks; the mothers were never on a broccoli sprouts diet).
“The experiment was terminated when the mean tumor diameter in the control mice exceeded 1.0 cm.
Our study indicates a prenatal/maternal BSp dietary treatment exhibited maximal preventive effects in inhibiting breast cancer development compared to postnatal early-life and adult BSp treatments in two transgenic mouse models that can develop breast cancer.
Postnatal early-life BSp treatment starting prior to puberty onset showed protective effects in prevention of breast cancer but was not as effective as the prenatal/maternal BSp treatment. However, adulthood-administered BSp diet did not reduce mammary tumorigenesis.
The prenatal/maternal BSp diet may:
Primarily influence histone modification processes rather than DNA methylation processes that may contribute to its early breast cancer prevention effects;
Exert its transplacental breast cancer chemoprevention effects through enhanced histone acetylation activator markers due to reduced HDAC1 expression and enzymatic activity.
This may be also due to the importance of a dietary intervention window that occurs during a critical oncogenic transition period, which is in early life for these two tested transgenic mouse models. Determination of a critical oncogenic transition period could be complicated in humans, which may partially explain the controversial findings of the adult BSp treatment on breast cancer development in the tested mouse models as compared the previous studies. Thus long-term consumption of BSp diet is recommended to prevent cancers in humans.”
“The dietary concentration for BSp used in the mouse studies was 26% BSp in formulated diet, which is equivalent to 266 g (~4 cups) BSp/per day for human consumption. Therefore, the concentration of BSp in this diet is physiological available and represents a practical consumption level in the human diet.
Prior to the experiment, we tested the potential influences of this prenatal/maternal BSp regimen on maternal and offspring health as well as mammary gland development in the offspring. Our results showed there was no negative effect of this dietary regimen on the above mentioned factors (data not shown) suggesting this diet is safe to use during pregnancy.”
I downgraded the study’s rating because I didn’t see where the sulforaphane active content of the diet was defined. It’s one thing to state:
“SFN as the most abundant and bioactive compound in the BSp diet has been identified as a potent HDAC inhibitor that preferably influences histone acetylation processes.”
and describe how sulforaphane may do this and may do that, and include it in the study’s title.
It’s another thing to quantify an animal study into findings that can help humans. Normal people aren’t going to eat “4 cups BSp/per day” but we may take one capsule of a sulforaphane dietary supplement when the price is $.20 a day.
The study’s food manufacturer offers dietary products to the public without quantifying all of the active contents like sulforaphane. Good for them if they can stay in business by serving customers who can’t be bothered with scientific evidence.
These researchers shouldn’t have conducted a study using the same lack of details as the food manufacturer provided, though. They should have either tasked the manufacturer to specify the sulforaphane active content, or contracted the analysis.
Regarding timing of a sulforaphane-based broccoli sprouts diet for humans, the study also didn’t provide evidence for recommending:
“Thus long-term consumption of BSp diet is recommended to prevent cancers in humans.”
“We evaluated the association between maternal antenatal depression and a novel biomarker of aging at birth, namely epigenetic gestational age (GA) based on fetal cord blood methylation data. We also examined whether this biomarker prospectively predicts and mediates maternal effects on early childhood psychiatric problems.
Maternal history of depression diagnosed before pregnancy and greater antenatal depressive symptoms were associated with child’s lower epigenetic GA. Child’s lower epigenetic GA, in turn, prospectively predicted total and internalizing problems and partially mediated the effects of maternal antenatal depression on internalizing problems in boys.”
Listening to a podcast by one of the coauthors, although the researchers’ stated intent was to determine the etiology of the findings, I didn’t hear any efforts to study the parents in sufficient detail to be able to detect possible intergenerational and transgenerational epigenetic inheritance causes and effects. There were the usual “associated with” and “it could be this, it could be that” hedges, which were also indicators of the limited methods employed toward the study’s limited design.
Why was an opportunity missed to advance human research in this area? Are researchers satisfied with non-causal individual differences non-explanations instead of making efforts in areas that may produce etiological findings?
The second 2018 epigenetic clock human study was from Alabama:
“We estimated measures of epigenetic age acceleration in 830 Caucasian participants from the Genetics Of Lipid Lowering Drugs and diet Network (GOLDN) considering two epigenetic age calculations.
Both DNA methylation age estimates were highly correlated with chronological age. We found that the Horvath and Hannum measures of epigenetic age acceleration were moderately correlated.
The Horvath age acceleration measure exhibited marginal associations with increased postprandial [after eating a meal] HDL [high-density lipoprotein], increased postprandial total cholesterol, and decreased soluble interleukin 2 receptor subunit alpha (IL2sRα). The Hannum measure of epigenetic age acceleration was inversely associated with fasting HDL and positively associated with postprandial TG [triglyceride], interleukin-6 (IL-6), C-reactive protein (CRP), and tumor necrosis factor alpha (TNFα).
The third 2018 epigenetic clock human study was a meta-analysis of cohorts from the UK, Italy, Sweden, and Scotland:
“The trajectories of Δage showed a declining trend in almost all of the cohorts with adult sample collections. This indicates that epigenetic age increases at a slower rate than chronological age, especially in the oldest population.
Some of the effect is likely driven by survival bias, where healthy individuals are those maintained within a longitudinal study, although other factors like underlying training population for the respective clocks may also have influenced this trend. It may also be possible that there is a ceiling effect for Δage whereby epigenetic clock estimates plateau.”
This 2018 Belgian review hijacked science to further an agenda:
“We addressed this issue at the LATSIS Symposium ‘Transgenerational Epigenetic Inheritance: Impact for Biology and Society’, in Zürich, 28–30 August 2017, and here provide important arguments why environmental and lifestyle-related exposures in young men should be studied.”
Putting that study’s graphic into human terms, F3 male great-grandchildren may be adversely affected by their F0 great-grandmothers being poisoned while pregnant with their F1 grandfathers, who – with their F2 fathers – may have also been adversely affected.
What the reviewer asserted without proof:
“The importance of maternal lifestyle, diet and other environmental exposures before and during gestation period is well recognized.”
is NOT TRUE for the studied area.
The evidence disproving this assertion is that NO scientifically adequate HUMAN studies of transgenerational epigenetic inheritance have been published!
There’s a huge gap between “The importance..is well recognized” of anything regarding transgenerational epigenetic inheritance and ZERO human studies.
Why has no one published scientifically adequate human evidence to demonstrate “Transgenerational Epigenetic Inheritance: Impact for Biology and Society” on ALL of the F1, F2, and F3 human generations as consequences “of maternal lifestyle, diet and other environmental exposures before and during gestation period?” What are we waiting for?
The reviewer said “young men should be studied” but said nothing about resolving bottlenecks in funding human research of the studied area. Do researchers have opportunities to make a NON-AGENDA-DRIVEN difference in this field?
With ZERO published human studies, can transgenerational epigenetic inheritance research be recharacterized into a female vs. male agenda? The reviewer’s attempt diminished the importance of research into human critical development periods.
“The defect in maternal care induced by gestational stress programs the development of the offspring.”
Will the reviewer’s suggested interventions – such as changing an adult’s lifestyle a long time after their development was altered – somehow make up for what went wrong early in their life, even before they were born?
“How can animal studies like the current study help humans when their models don’t replicate common human conditions? This failure to use more relevant models has follow-on effects such as human intergenerational and transgenerational epigenetic inheritance being denigrated due to insufficient evidence.”
“The review focused on 0.0001% of the prenatal period for what matters with the human male – who he was at the time of a Saturday night drunken copulation – regarding intergenerational and transgenerational epigenetic inheritance of metabolic diseases.
The human female’s role – who she was at conception AND THEN what she does or doesn’t do during the remaining 99.9999% of the prenatal period to accommodate the fetus and prevent further adverse epigenetic effects from being intergenerationally and transgenerationally transmitted – wasn’t discussed.
This 2018 Washington rodent study subject was transgenerational epigenetic inheritance caused by a fungicide that’s been phased out or banned for over a decade:
“This study was designed to help understand how three different epigenetic processes in sperm are correlated with vinclozolin-induced epigenetic transgenerational inheritance of disease.
Most DMRs [differential DNA-methylated regions] identified in this study are unique between the F1, F2, and F3 generations.
The number of lncRNA was much higher than the number of sncRNA [small noncoding RNA, including microRNA]. The overlap between each generation was very low or nonexistent.
The F1 and the F2 generation control versus vinclozolin lineage sperm had negligible DHRs [differential histone retention sites]. This observation suggests that the direct vinclozolin exposure does not alter histone retention or trigger any changes. However, the F3 generation control versus vinclozolin lineage sperm DHRs increased considerably.
It appears that the phenomenon is more complex than just a direct exposure triggering the formation of epimutations that are then simply maintained in the subsequent generations.”
I asked the coauthors why a third of the cited references were self-referencing. The lead author replied:
“The field in epigenetic transgenerational inheritance is expanding, however it is still hard for us to find relevant studies in rodents or human that we can cite. Most of the time DNA methylation, ncRNA and histone modifications are investigated from a direct exposure and/or from a purely mechanistic angle (e.g. DNA methylation of specific genes).
In contrast, transgenerational phenotypes and toxicology by definition excludes direct exposure and must be transmitted through multiple generations (the F3 generation is the first transgenerational one). We are not looking at specific genes but using whole genome sequencing technologies which is a broader approach.
Besides, if you do a pubmed search with the keywords “epigenetics” and “transgenerational”, you will probably find that more than 50% of the studies have been done by Dr Michael K. Skinner. He is also one of the first researcher who started to work on the epigenetic transgenerational inheritance phenomenon 15 years ago. Not citing his previous work is challenging.
We hope to see other labs contributing to this particular field and we will be delighted to cite them. In the meantime, our only option is to reference our previous work.”
“Thank you for your reply! It must be exasperating to see other researchers stop their studies short of the F3 generation for no apparent or disclosed reason.
Have you seen even one scientifically adequate human study of transgenerational epigenetic inheritance?”
This 2018 German rodent study was a proof-of-principle for immune epigenetic memory in the brain:
“Innate immune memory is a vital mechanism of myeloid [bone marrow] cell plasticity that occurs in response to environmental stimuli and alters subsequent immune responses.
Two types of immunological imprinting can be distinguished – training and tolerance. These are epigenetically mediated and enhance or suppress subsequent inflammation, respectively.
Certain immune stimuli train blood monocytes to generate enhanced immune responses to subsequent immune insults. By contrast, other stimuli induce immune tolerance — suppression of inflammatory responses to subsequent stimuli.
Microglia (brain-resident macrophages) are very long-lived cells. This makes them particularly interesting for studying immune memory, as virtually permanent modification of their molecular profile appears possible.
In a mouse model of Alzheimer’s pathology, immune training exacerbates cerebral β-amyloidosis and immune tolerance alleviates it; similarly, peripheral immune stimulation modifies pathological features after stroke. Our results identify immune memory in the brain as an important modifier of neuropathology.
Immune memory in the brain is predominantly mediated by microglia..Immune memory in the brain could conceivably affect the severity of any neurological disease that presents with an inflammatory component, but this will need to be studied for each individual condition.”
The researchers performed multiple experiments to test different hypotheses about how immune-response experiences are remembered. Modifications to histone methylation and acetylation were targeted. The dosage of the stimulus needed to produce immune tolerance was usually four times the immune training dosage.