Exposure to endocrine-disrupting chemicals can alter normal physiology and increase susceptibility to non-communicable diseases like obesity. Especially the prenatal and early postnatal period is highly vulnerable to adverse effects by environmental exposure, promoting developmental reprogramming by epigenetic alterations. To obtain a deeper insight into the role of prenatal bisphenol A (BPA) exposure in children’s overweight development, we combine epidemiological data with experimental models and BPA-dependent DNA methylation changes. BPA concentrations were measured in maternal urine samples of the LINA mother-child-study obtained during pregnancy (n = 552), and BPA-associated changes in cord blood DNA methylation were analyzed by Illumina Infinium HumanMethylation450 BeadChip arrays (n = 472). Methylation changes were verified by targeted MassARRAY analyses, assessed for their functional translation by qPCR and correlated with children’s body mass index (BMI) z scores at the age of 1 and 6 years. Further, female BALB/c mice were exposed to BPA from 1 week before mating until delivery, and weight development of their pups was monitored (n ≥ 8/group). Additionally, human adipose-derived mesenchymal stem cells were treated with BPA during the adipocyte differentiation period and assessed for exposure-related epigenetic, transcriptional and morphological changes (n = 4). In prenatally BPA-exposed children two CpG sites with deviating cord blood DNA-methylation profiles were identified, among them a hypo-methylated CpG in the promoter of the obesity-associated mesoderm-specific transcript (MEST). A mediator analysis suggested that prenatal BPA exposure was connected to cord blood MEST promoter methylation and MEST expression as well as BMI z scores in early infancy. This effect could be confirmed in mice in which prenatal BPA exposure altered Mest promoter methylation and transcription with a concomitant increase in the body weight of the juvenile offspring. An experimental model of in vitro differentiated human mesenchymal stem cells also revealed an epigenetically induced MEST expression and enhanced adipogenesis following BPA exposure. Our study provides evidence that MEST mediates the impact of prenatal BPA exposure on long-term body weight development in offspring by triggering adipocyte differentiation.

Many recent epigenetic studies report that cigarette smoking reduces DNA methylation in whole blood at the single CpG site cg19859270 within the GPR15 gene. Within two independent cohorts, we confirmed the differentially expression of the GPR15 gene when smokers and non-smokers subjects are compared. By validating the GPR15 protein expression at the cellular level, we found that the observed decreased methylation at this site in white blood cells (WBC) of smokers is mainly caused by the high proportion of CD3+GPR15+ expressing T cells in peripheral blood. In current smokers, the percentage of GPR15+ cells among CD3+ T cells in peripheral blood is significantly higher (15.5 ± 7.2 %, mean ± standard deviation) compared to non-smokers (3.7 ± 1.6 %). Treatment of peripheral blood mononuclear cell (PBMC) cultures with aqueous cigarette smoke extract did not induce a higher proportion of this T cell subtype. Our results underline that DNA hypomethylation at cg19859270 site, observed in WBCs of smokers, did not arise by direct effect of tobacco smoking compounds on methylation of DNA but rather by the enrichment of a tobacco-smoking-induced lymphocyte population in the peripheral blood.

Tobacco smoke is worldwide one of the main preventable lifestyle inhalative pollutants causing severe adverse health effects. Epidemiological studies revealed association of tobacco smoking with epigenetic changes at single CpGs in blood. However, the biological relevance of the often only marginal methylation changes remains unclear. Comparing genome-wide changes in CpG methylation of three recently reported epidemiological datasets, two obtained on whole blood and one on peripheral blood mononuclear cells (PBMCs), it becomes evident that the majority of methylation changes (86.7 and 93.3 %) in whole blood account for changes in granulocytes. Analyzing, in more detail, seven highly significant reported smoking-induced methylation changes at single CpGs in different blood cell types of healthy volunteers (n = 32), we confirmatively found a strong cell-type specificity. Two CpGs in GFI1 and F2RL3 were significantly hypomethylated in granulocytes (−11.3 %, p = 0.001; −8.7 %, p = 0.001, respectively) but not in PBMCs of smokers while two CpGs in CPOX and GPR15 were found to be hypomethylated in PBMC (−4.3 %, p = 0.003; −4.2 %, P = 0.009, respectively) and their subtypes of GPR15 non-expressing (−3.2 %, p = 0.027; −2.5 %, p = 0.032, respectively) and smoking-evoked GPR15 expressing T cells (−15.8 %, p < 0.001; −13.8 %, p = 0.018, respectively) but not in granulocytes. In contrast, cg05575921 within AHRR was hypomethylated in every analyzed cell type of smokers, but with a different degree. Both, hypomethylation at cg05575921 in granulocytes (−55.2 % methylation change in smokers, p < 0.001) and the frequency of GPR15+ T cells (9.8–37.1 % in smokers), possessing a specific hypomethylation at cg19859270, were strongly associated with smoking behavior at individual level and could therefore serve as valuable biomarkers indicating a disturbed homeostasis in smokers. In contrast to the reported long-term persistent methylation changes in adult smokers after cessation, the hypomethylation at cg05575921 in prenatally tobacco smoke-exposed children (n = 13) from our LINA cohort was less stable and disappeared already within 2 years after birth. Studying cell type-specific methylation changes provides helpful information regarding the biological relevance of epigenetic modifications. Here, we could show that smoking differently affects both cells of the innate and adaptive immune systems.

It was postulated that 3D cell culture models more accurately reflect the complex tissue physiology and morphology in comparison to 2D cell monolayers. Currently, there is a shortage of well-characterized and easily maintainable high-throughput experimental models of the human placenta. Here, we characterized three different 3D cultures (e.g., spheroids) derived from trophoblast cell lines and studied their functionality in comparison to primary fetal trophoblasts and placental tissue. The spheroid growth rates of JEG3, BeWo and HTR8/SVneo cell lines were similar among each other and were significantly larger in comparison to primary trophoblast spheroids. All spheroids exhibited migratory properties and shortest distances were registered for JEG3 spheroids. Even though all spheroids displayed invasive capabilities, only the invasive features of HTR8/SVneo spheroids resulted in specific branching. This was in agreement with the invasive properties of the spheroids obtained from primary trophoblasts. Human chorionic gonadotropin production was highest in JEG3 spheroids and only increased when stimulated with cAMP and forskolin in BeWo, but not HTR8/SVneo spheroids. The gene expression analysis confirmed that 3D trophoblast cell cultures and especially HTR8/SVneo spheroids showed considerable similarities with the gene expression profile of primary placental tissue. This study offers a broad characterization of 3D trophoblast spheroids that, in turn, can help in selecting the best model depending on the scientific question that needs to be answered.

To date, little is known about the unique contributions of specialized human DC subsets to protection against tuberculosis (TB). Here, we focus on the role of human plasmacytoid (p)DCs and myeloid (m)DCs in the immune response to the TB vaccine bacille Calmette‐Guérin (BCG). Ex vivo DC subsets from human peripheral blood were purified and infected with BCG expressing GFP to distinguish between infected and noninfected cells. BDCA‐1⁺ myeloid DCs were more susceptible than BDCA‐3⁺ mDCs to BCG infection. Plasmacytoid DCs have poor phagocytic activity but are equipped with endocytic receptors and can be activated by bystander stimulation. Consequently, the mutual interaction of the two DC subsets in response to BCG was analyzed. We found that pDCs were activated by BCG‐infected BDCA‐1⁺ mDCs to upregulate maturation markers and to produce granzyme B, but not IFN‐α. Reciprocally, the presence of activated pDCs enhanced mycobacterial growth control by infected mDCs and increased IL‐1β availability. The synergy between the two DC subsets promoted BCG‐specific CD8⁺ T‐cell stimulation and the role of BCG‐infected BDCA‐1⁺ mDCs could not be efficiently replaced by infected BDCA‐3⁺ mDCs in the crosstalk with pDCs. We conclude that mDC–pDC crosstalk should be exploited for rational design of next‐generation TB vaccines.

Both genome-wide association studies (GWAS) and epigenome-wide association studies (EWAS) are aiming to discover molecular signs for diseases, which possibly can be helpful for future therapeutic intervention strategies. The most prominently used tissue in association studies on humans is venous blood. In contrast to the unchangeable genotype, epigenetic DNA methylation is more variable. Methylation is affected not only by a subject’s constitution such as age, gender, ethnicity, genotype, lifestyle and health status, but is also determined by tissue-specific cell types. PubMed, published before 2017, was researched, documenting the importance of epigenetic analyses on single cell types instead of whole blood in EWAS. Initial studies documented that stressor-induced, mostly marginal, DNA methylation changes in whole-blood samples (< 5% methylation difference) may rely not on uniform distribution of that methylation shift among each blood cell type, but on strongly altered methylation (> 20%) in single cell types. The effect size in single cell types enables the performance of epigenome-wide studies on replicated smaller cohorts, in contrast to the requirement of larger international consortium-based approaches. Therefore, the identification of a specific cell type that is responsible for association between DNA methylation in whole blood with the phenotype of interest, has to be a prioritized experimental approach in association studies. This is a key prerequisite for constructive interpretation of epigenetic signs in the context of diverse biological function of the tissue blood, for detection of causality link between methylation and phenotype and for establishment of valuable clinical biomarkers and therapeutic targets.