Gestational diabetes in mice induces hematopoietic memory that affects the long-term health of the offspring.

Gestational diabetes is a common medical complication of pregnancy that is associated with adverse perinatal outcomes and an increased risk of metabolic diseases and atherosclerosis in adult offspring. The mechanisms responsible for this delayed pathological transmission remain unknown. In mouse models, we found that the development of atherosclerosis in adult offspring born to diabetic pregnancy can be in part linked to hematopoietic alterations. Although they do not show any gross metabolic disruptions, the adult offspring maintain hematopoietic features associated with diabetes, indicating the acquisition of a lasting diabetic hematopoietic memory. We show that the induction of this hematopoietic memory during gestation relies on the activity of the advanced glycation end product receptor (AGER) and the nucleotide binding and oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome, which lead to increased placental inflammation. In adult offspring, we find that this memory is associated with DNA methyltransferase 1 (DNMT1) upregulation and epigenetic changes in hematopoietic progenitors. Together, our results demonstrate that the hematopoietic system can acquire a lasting memory of gestational diabetes and that this memory constitutes a pathway connecting gestational health to adult pathologies.

Slow cycling and durable Flt3+ progenitors contribute to hematopoiesis under native conditions.

The dynamics of the hematopoietic flux responsible for blood cell production in native conditions remains a matter of debate. Using CITE-seq analyses, we uncovered a distinct progenitor population that displays a cell cycle gene signature similar to the one found in quiescent hematopoietic stem cells. We further determined that the CD62L marker can be used to phenotypically enrich this population in the Flt3+ multipotent progenitor (MPP4) compartment. Functional in vitro and in vivo analyses validated the heterogeneity of the MPP4 compartment and established the quiescent/slow-cycling properties of the CD62L- MPP4 cells. Furthermore, studies under native conditions revealed a novel hierarchical organization of the MPP compartments in which quiescent/slow-cycling MPP4 cells sustain a prolonged hematopoietic activity at steady-state while giving rise to other lineage-biased MPP populations. Altogether, our data characterize a durable and productive quiescent/slow-cycling hematopoietic intermediary within the MPP4 compartment and highlight early paths of progenitor differentiation during unperturbed hematopoiesis.

Role of the hematopoietic stem cells in immunological memory.

Purpose of review: Immunological memory is an important evolutionary adaptation of the immune system. Previously restricted to the adaptive immune system, the concept of memory has recently been broadened to the innate immune system. This review summarizes recent studies that highlight the contribution of the hematopoietic stem cells (HSCs) in supporting immunological memory. Recent findings: Short-lived innate immune cells can build a long-lasting memory of infection to improve their response to secondary challenges. Studies show that these unexpected properties of the innate immune system are sustained by epigenetic and metabolic changes in the HSC compartment. Summary: HSCs are durably altered in response to pathogens and serve as long-term support for innate immune memory. Many questions remain regarding the mechanisms contributing to the induction and the maintenance of this immune memory in HSCs. Answering these questions will open new perspectives to understand how environmental factors shape the HSC activity over time.

Three-Generation Study of Male Rats Gestationally Exposed to High Butterfat and Bisphenol A: Impaired Spermatogenesis, Penetrance with Reduced Severity.

Gestational high butterfat (HFB) and/or endocrine disruptor exposure was previously found to disrupt spermatogenesis in adulthood. This study addresses the data gap in our knowledge regarding transgenerational transmission of the disruptive interaction between a high-fat diet and endocrine disruptor bisphenol A (BPA). F0 generation Sprague-Dawley rats were fed diets containing butterfat (10 kcal%) and high in butterfat (39 kcal%, HFB) with or without BPA (25 µg/kg body weight/day) during mating and pregnancy. Gestationally exposed F1-generation offspring from different litters were mated to produce F2 offspring, and similarly, F2-generation animals produced F3-generation offspring. One group of F3 male offspring was administered either testosterone plus estradiol-17ß (T + E2) or sham via capsule implants from postnatal days 70 to 210. Another group was naturally aged to 18 months. Combination diets of HFB + BPA in F0 dams, but not single exposure to either, disrupted spermatogenesis in F3-generation adult males in both the T + E2-implanted group and the naturally aged group. CYP19A1 localization to the acrosome and estrogen receptor beta (ERbeta) localization to the nucleus were associated with impaired spermatogenesis. Finally, expression of methyl-CpG-binding domain-3 (MBD3) was consistently decreased in the HFB and HFB + BPA exposed F1 and F3 testes, suggesting an epigenetic component to this inheritance. However, the severe atrophy within testes present in F1 males was absent in F3 males. In conclusion, the HFB + BPA group demonstrated transgenerational inheritance of the impaired spermatogenesis phenotype, but severity was reduced in the F3 generation.

Low-Dose Bisphenol A in a Rat Model of Endometrial Cancer: A CLARITY-BPA Study.

BACKGROUND: Bisphenol A (BPA) is known to be biologically active in experimental models even at low levels of exposure. However, its impact on endometrial cancer remains unclear. OBJECTIVES: This study aimed to investigate whether lifelong exposure to different doses of BPA induced uterine abnormalities and molecular changes in a rat model. METHODS: Sprague-Dawley rats were exposed to 5 doses of BPA [0, 25, 250, 2,500, or 25,000µg/kg body weight (BW)/d] or 2 doses of 17α-ethynylestradiol (EE2) (0.05 and 0.5µg/kg BW/d) starting from gestational day 6 up to 1 y old according to the CLARITY-BPA consortium protocol. The BW, uterus weight, and histopathology end points of the uteri were analyzed at postnatal (PND) day 21, 90, and 365. Estrous cycling status was evaluated in PND90 and PND365 rats. Transcriptomic analyses of estrus stage uteri were conducted on PND365 rats. RESULTS: Based on the analysis of the combined effects of all testing outcomes (including immunohistological, morphological, and estrous cycle data) in a semiblinded fashion, using statistical models, 25µg/kg BW/d BPA [BPA(25)], or 250µg/kg BW/d BPA [BPA(250)] exerted effects similar to that of EE2 at 0.5µg/kg BW/d in 1-y-old rats. Transcriptome analyses of estrus stage uteri revealed a set of 710 genes shared only between the BPA(25) and BPA(250) groups, with 115 of them predicted to be regulated by estradiol and 57 associated with female cancers. An interesting finding is that the expression of 476 human orthologous genes in this rat BPA signature robustly predicted the overall survival (p=1.68×10-5, hazard ratio=2.62) of endometrial cancer patients. DISCUSSION: Lifelong exposure of rats to low-dose BPA at 25 and 250µg/kg BW/d altered the estrous cycle and uterine pathology with similarity to EE2. The exposure also disrupted a unique low-dose BPA-gene signature with predictive value for survival outcomes in patients with endometrial cancer. https://doi.org/10.1289/EHP6875.

FOXO activity adaptation safeguards the hematopoietic stem cell compartment in hyperglycemia.

Hematopoietic stem cell (HSC) activity is tightly controlled to ensure the integrity of the hematopoietic system during the organism's lifetime. How the HSC compartment maintains its long-term fitness in conditions of chronic stresses associated with systemic metabolic disorders is poorly understood. In this study, we show that obesity functionally affects the long-term function of the most immature engrafting HSC subpopulation. We link this altered regenerative activity to the oxidative stress and the aberrant constitutive activation of the AKT signaling pathway that characterized the obese environment. In contrast, we found minor disruptions of the HSC function in obese mice at steady state, suggesting that active mechanisms could protect the HSC compartment from its disturbed environment. Consistent with this idea, we found that FOXO proteins in HSCs isolated from obese mice become insensitive to their normal upstream regulators such as AKT, even during intense oxidative stress. We established that hyperglycemia, a key condition associated with obesity, is directly responsible for the alteration of the AKT-FOXO axis in HSCs and their abnormal oxidative stress response. As a consequence, we observed that HSCs isolated from a hyperglycemic environment display enhanced resistance to oxidative stress and DNA damage. Altogether, these results indicate that chronic metabolic stresses associated with obesity and/or hyperglycemia affect the wiring of the HSCs and modify their oxidative stress response. These data suggest that the uncoupling of FOXO from its environmental regulators could be a key adaptive strategy that promotes the survival of the HSC compartment in obesity.

Obesity alters the long-term fitness of the hematopoietic stem cell compartment through modulation of Gfi1 expression.

Obesity is a chronic organismal stress that disrupts multiple systemic and tissue-specific functions. In this study, we describe the impact of obesity on the activity of the hematopoietic stem cell (HSC) compartment. We show that obesity alters the composition of the HSC compartment and its activity in response to hematopoietic stress. The impact of obesity on HSC function is progressively acquired but persists after weight loss or transplantation into a normal environment. Mechanistically, we establish that the oxidative stress induced by obesity dysregulates the expression of the transcription factor Gfi1 and that increased Gfi1 expression is required for the abnormal HSC function induced by obesity. These results demonstrate that obesity produces durable changes in HSC function and phenotype and that elevation of Gfi1 expression in response to the oxidative environment is a key driver of the altered HSC properties observed in obesity. Altogether, these data provide phenotypic and mechanistic insight into durable hematopoietic dysregulations resulting from obesity.

Tuning of the Hematopoietic Stem Cell Compartment in its Inflammatory Environment.

PURPOSE OF REVIEW: The hematopoietic stem cell (HSC) compartment is the cornerstone of a lifelong blood cell production but also contributes to the ability of the hematopoietic system to dynamically respond to environmental challenges. This review summarizes our knowledge about the interaction between HSCs and its inflammatory environment during life and questions how its disruption could affect the health of the hematopoietic system. RECENT FINDINGS: The latest research demonstrates the direct role of inflammatory signals in promoting the emergence of the HSCs during development and in setting their steady-state activity in adults. They indicate that inflammatory patho-physiological conditions or immunological history could shape the structure and biology of the HSC compartment, therefore altering its overall fitness. SUMMARY: Through instructive and/or selective mechanisms, the inflammatory environment seems to provide a key homeostatic signal for HSCs. Although the mechanistic basis of this complex interplay remains to be fully understood, its dysregulation has broad consequences on HSC physiology and the development of hematological diseases. As such, developing experimental models that fully recapitulate a normal basal inflammatory state could be essential to fully assess HSC biology in native conditions.

Gestational high-fat diet and bisphenol A exposure heightens mammary cancer risk.

In utero exposure to bisphenol A (BPA) increases mammary cancer susceptibility in offspring. High-fat diet is widely believed to be a risk factor of breast cancer. The objective of this study was to determine whether maternal exposure to BPA in addition to high-butterfat (HBF) intake during pregnancy further influences carcinogen-induced mammary cancer risk in offspring, and its dose-response curve. In this study, we found that gestational HBF intake in addition to a low-dose BPA (25 µg/kg BW/day) exposure increased mammary tumor incidence in a 50-day-of-age chemical carcinogen administration model and altered mammary gland morphology in offspring in a non-monotonic manner, while shortening tumor-free survival time compared with the HBF-alone group. In utero HBF and BPA exposure elicited differential effects at the gene level in PND21 mammary glands through DNA methylation, compared with HBF intake in the absence of BPA. Top HBF + BPA-dysregulated genes (ALDH1B1, ASTL, CA7, CPLX4, KCNV2, MAGEE2 and TUBA3E) are associated with poor overall survival in The Cancer Genomic Atlas (TCGA) human breast cancer cohort (n = 1082). Furthermore, the prognostic power of the identified genes was further enhanced in the survival analysis of Caucasian patients with estrogen receptor-positive tumors. In conclusion, concurrent HBF dietary and a low-dose BPA exposure during pregnancy increases mammary tumor incidence in offspring, accompanied by alterations in mammary gland development and gene expression, and possibly through epigenetic reprogramming.

High butter-fat diet and bisphenol A additively impair male rat spermatogenesis.

Exposure to xenoestrogens is a probable cause of male infertility in humans. Consumption of high-fat diets and exposure to bisphenol A (BPA) is pervasive in America. Here, we test the hypothesis that gestational exposure to high dietary fats and/or BPA disrupt spermatogenesis in adulthood. Sprague-Dawley rats were fed diets containing 10kcal% butter fat (AIN), 39kcal% butter fat (HFB), or 39kcal% olive oil (HFO), with or without BPA (25µg/kg body weight/day) during pregnancy. One group of male offspring received testosterone (T)- and estradiol-17ß (E2)-filled implants or sham-implants from postnatal day (PND)70-210. Another group was naturally aged to 18 months. We found that adult males with gestational exposure to BPA, HFB, or HFB+BPA, in both the aged group and the T+E2-implanted group, exhibited impairment of spermatogenesis. In contrast, gestational exposure to HFO or HFO+BPA did not affect spermatogenesis. Sham-implanted, gestational exposed groups also had normal spermatogenesis. Loss of ERα expression in round spermatids and premature expression of protamine-1 in diplotene spermatocytes were features associated with impaired spermatogenesis. Compared with the single-treatment groups, the HFB+BPA group experienced more severe effects, including atrophy.

Data on spermatogenesis in rat males gestationally exposed to bisphenol A and high fat diets.

This data article contains supporting information regarding the research article entitled "High butter-fat diet and bisphenol A additively impair male rat spermatogenesis" (P. Tarapore, M. Hennessy, D. Song, J. Ying, B. Ouyang, V. Govindarajah, et al.,) [1]. Sprague-Dawley females were fed AIN, high fat butter, 17α-ethinyl estradiol, or high fat butter plus four bisphenol A doses (2500 µg/kg bw-d, 250 µg/kg bw-d, 25 µg/kg bw-d, and 2.5 µg/kg bw-d) before and during pregnancy. All diets were switched to AIN after the pups were born. Male offspring received testosterone (T)- and estradiol-17ß (E2)-filled implants from postnatal day 70-210 for 20 weeks (T+E2 rat model). The testes were weighed, and examined for impairments in spermatogenesis.

A community survey on knowledge of the impact of environmental and epigenetic factors on health and disease.

AIM: An outreach effort was designed to survey breast cancer survivors, supporters and their families and friends with respect to their interest in, and knowledge of, the potential impact of the environment and epigenetics on health. METHODS: Two nearly identical questionnaires (one for adolescents and one for adults) were designed to gauge the perception of this community as to whether the environment impacts health and cancer risk through processes other than genetics. The questionnaires were filled out at casual social gatherings, fundraisers and wellness campaigns as well as in schools (730 participants). The differences among correct (scientific consensus) versus other responses (incorrect and not known) were evaluated. Each answer was first analysed individually and then grouped into one of three categories (diet, inheritance and environment) with age, race and gender. Differences for each response, question or group were compared by repeated measures analysis of variance. RESULTS: Respondents generally acknowledged that many factors could be associated with breast cancer although answers to key questions related to epigenetics based on diet, inheritance and environment were often incorrect or not known. The adult participants tended to answer more questions correctly than adolescents did. The majority of participants preferred the Internet as a major source for obtaining further information. CONCLUSION: The growing awareness and educational needs for adolescents may bring new paradigm-related environmental risk factors, which may minimise negative epigenetic outcome in subsequent generations. There is an educational opportunity, especially using electronic media, for public education concerning the impact of the environment on human health.

In utero exposure of rats to high-fat diets perturbs gene expression profiles and cancer susceptibility of prepubertal mammary glands.

Human studies suggest that high-fat diets (HFDs) increase the risk of breast cancer. The 7,12-dimethylbenz[a]anthracene (DMBA)-induced mammary carcinogenesis rat model is commonly used to evaluate the effects of lifestyle factors such as HFD on mammary tumor risk. Past studies focused primarily on the effects of continuous maternal exposure on the risk of offspring at the end of puberty (PND50). We assessed the effects of prenatal HFD exposure on cancer susceptibility in prepubertal mammary glands and identified key gene networks associated with such disruption. During pregnancy, dams were fed AIN-93G-based diets with isocaloric high olive oil, butterfat or safflower oil. The control group received AIN-93G. Female offspring were treated with DMBA on PND21. However, a significant increase in tumor volume and a trend of shortened tumor latency were observed in rats with HFD exposure against the controls (P=.048 and P=.067, respectively). Large-volume tumors harbored carcinoma in situ. Transcriptome profiling identified 43 differentially expressed genes in the mammary glands of the HFBUTTER group as compared with control. Rapid hormone signaling was the most dysregulated pathway. The diet also induced aberrant expression of Dnmt3a, Mbd1 and Mbd3, consistent with potential epigenetic disruption. Collectively, these findings provide the first evidence supporting susceptibility of prepubertal mammary glands to DMBA-induced tumorigenesis that can be modulated by dietary fat that involves aberrant gene expression and likely epigenetic dysregulation.