Prenatal caffeine exposure induces a poor quality of articular cartilage in male adult offspring rats via cholesterol accumulation in cartilage

Effect of caffeine intake on self-reported and genetic prediction of osteoarthritis: an epidemiological study and Mendelian randomization analysis

Background

Osteoarthritis (OA) holds the distinction of being the most widespread musculoskeletal disorder. Any disruptions in the integrity of the articular cartilage can result in joint malfunction, discomfort, and impaired physical functioning. Increasing evidence indicates the negative impacts of caffeine intake on hyaline cartilage. The primary objective of this study was to delve deeper into understanding the potential link between the consumption of caffeine and the risk of developing OA.

Methods

In this study, we constructed logistic regression models to evaluate the correlation between caffeine consumption and the risk of osteoarthritis using data from the National Health and Nutrition Examination Survey. Following that, we utilized genome-wide association studies to conduct a Mendelian randomization (MR) analysis investigating the association between coffee consumption and the likelihood of developing knee OA. We employed various statistical methods, including inverse variance weighting (IVW), weighted median, weighted mode, simple mode, and MR-Egger regression, to ensure comprehensive analysis and robust conclusions. To evaluate heterogeneity and the potential impact of pleiotropy, we conducted several statistical tests, including Cochran's Q test, MR-Egger intercept test, MR Pleiotropy RESidual Sum and Outlier test (MR-PRESSO), and MR Steiger test.

Results

The weighted multivariate logistic regression analysis showed that the relationship between high caffeine intake (95-206 and ≥206 mg/day) and OA prevalence remained significantly high even after adjusting for covariates using the lowest caffeine intake (< 11 mg/day) as reference: Model 1-OR (95% Cl) = 1.365 (1.18-1.58) and 1.59 (1.38-1.83); Model 2-OR (95% Cl) = 1.21 (1.04-1.42) and 1.44 (1.23-1.68); and Model 3-OR (95% Cl) = 1.19 (1.01-1.40) and 1.30 (1.10-1.52), respectively (p < 0.05). The findings from the fixed effects inverse variance weighted (IVW) analysis revealed a statistically significant link between coffee intake and the likelihood of developing knee osteoarthritis: OR = 1.94; 95% confidence interval (Cl) =1.471-2.517; (p < 0.001). Consistent findings were obtained across various other methods, including MR-Egger regression, weighted median, weighted mode, and simple mode analyses.

Conclusion

Our study showed a positive correlation between OA prevalence and high caffeine intake (≥95 mg/day).

The effect of coffee consumption on three main bone disorders: a Mendelian randomization trial

INTRODUCTION

Despite a large number of observational studies examining the effect of coffee consumption(CC) on bone disorders(BDs), particularly, osteoarthritis(OA), osteoportic fracture(OF), and rheumatoid arthritis(RA), the conclusions are highly controversial. Thus, it is essential to examine the causal association between CC and BDs.

MATERIALS AND METHODS

Mendelian randomization (MR) analysis was performed to assess the causal influence of CC on OF, RA, and OA. The main endpoint was the odds ratio (OR) of the inverse variance weighted (IVW) approach. In addition, the weighted median (WM), MR-Egger regressions, MR-pleiotropy residual sum and outlier (MR-PRESSO) and multivariable MR (MVMR) were included in sensitivity analyses. Furthermore, the function of causal SNPs was evaluated by gene ontology (GO) analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis, and protein-protein interaction networks.

RESULTS

Primary MR analysis based on the IVW method suggested that changes in CC alter risk of OF (OR = 1.383, 95%CI 1.079-1.853, P = 0.039), RA(OR: 1.623, 95%CI 1.042-2.527, P = 0.032) and HOA (hip osteoarthritis, OR = 1.536, 95% CI 1.044-2.259, P = 0.021). However, these causal relationships were not robust in sensitivity analyses. In contrast, there is a positive causal relationship between increased CC and the risk of KOA (knee osteoarthritis, OR: 2.094, 95%CI: 1.592-2.754, P = 1.41 × 10-7), as evidenced by the IVW using random effect. A similar effect size was observed across all MR sensitivity analyses, with no evidence of horizontal pleiotropy.

CONCLUSION

Based on our MR analysis, increased CC was causally linked to an increase in the risk of KOA. Genetic predictions suggested that CC reduction may have benefits for bone health.

High Cholesterol-Induced Bone Loss Is Attenuated by Arctiin via an Action in Osteoclasts

High cholesterol-induced bone loss is highly associated with oxidative stress, which leads to the generation of oxysterols, such as 7-ketocholesterol (7-KC). Here, we conducted in vivo and in vitro experiments to determine whether arctiin prevents high cholesterol diet-induced bone loss by decreasing oxidative stress. First, arctiin was orally administered to atherogenic diet (AD)-fed C57BL/6J male mice at a dose of 10 mg/kg for 6 weeks. Micro-computerized tomography (μCT) analysis showed that arctiin attenuated AD-induced boss loss. For our in vitro experiments, the anti-oxidant effects of arctiin were evaluated in 7-KC-stimulated osteoclasts (OCs). Arctiin decreased the number and activity of OCs and inhibited autophagy by disrupting the nuclear localization of transcription factor EB (TFEB) and downregulating the oxidized TFEB signaling pathway in OCs upon 7-KC stimulation. Furthermore, arctiin decreased the levels of reactive oxygen species (ROS) by enhancing the expression of nuclear factor erythroid 2-related factor 2 (Nrf2), catalase, and heme oxygenase 1 (HO-1), all of which affected OC differentiation. Conversely, silencing of Nrf2 or HO-1/catalase attenuated the effects of arctiin on OCs. Collectively, our findings suggested that arctiin attenuates 7-KC-induced osteoclastogenesis by increasing the expression of ROS scavenging genes in the Nrf2/HO-1/catalase signaling pathway, thereby decreasing OC autophagy. Moreover, arctiin inhibits the oxidation and nuclear localization of TFEB, thus protecting mice from AD-induced bone loss. Our findings thus demonstrate the therapeutic potential of arctiin for the prevention of cholesterol-induced bone loss.

Prenatal caffeine exposure induced renal developmental toxicity and transgenerational effect in rat offspring

Epidemiological studies revealed that prenatal caffeine exposure (PCE) is associated with adverse gestational outcomes and susceptibility to chronic diseases in offspring, yet the effects of PCE on glomerulosclerosis susceptibility in adult female offspring and its intergenerational transmission remain to be further investigated. Here, we found that PCE caused fetal kidney dysplasia and glomerulosclerosis of the female offspring. Besides, the kidney of F1 offspring in PCE group exhibited the "low expressional programming of AT2R" and "GC-IGF1 programming" alteration. Intergenerational genetic studies revealed that the renal defect and GC-IGF1 programming alteration was inherited to F2 adult female offspring derived from the female germ line, but Low expression of AT2R did not extend to the F2 female offspring. Taken together, PCE caused renal dysplasia and adult glomerulosclerosis in the F1 female offspring, which might be mediated by renal AT2R low expressional programming and GC-IGF1 axis alteration. Furthermore, PCE induced transgenerational toxicity on kidney, and GC-IGF1 programming alteration might be the potential molecular mechanism. This study provided experimental evidence for the mechanism study of the intergenerational inheritance of kidney developmental toxicity caused by PCE.

H3K9ac of TGFβRI in human umbilical cord: a potential biomarker for evaluating cartilage differentiation and susceptibility to osteoarthritis via a two-step strategy

Background

Epidemiological investigation and our previous reports indicated that osteoarthritis had a fetal origin and was closely associated with intrauterine growth retardation (IUGR). Human Wharton’s jelly-derived mesenchymal stem cells (WJ-MSCs) could be programmable to “remember” early-life stimuli. Here, we aimed to explore an early-warning biomarker of fetal-originated adult osteoarthritis in the WJ-MSCs.

Methods

Firstly, two kinds of WJ-MSCs were applied to evaluate their chondrogenic potential in vitro through inducing chondrogenic differentiation as the first step of our strategy, one from newborns with IUGR and the other from normal newborns but treated with excessive cortisol during differentiation to simulate the excessive maternal glucocorticoid in the IUGR newborns. As for the second step of the strategy, the differentiated WJ-MSCs were treated with interleukin 1β (IL-1β) to mimic the susceptibility to osteoarthritis. Then, the expression and histone acetylation levels of transforming growth factor β (TGFβ) signaling pathway and the expression of histone deacetylases (HDACs) were quantified, with or without cortisol receptor inhibitor RU486, or HDAC4 inhibitor LMK235. Secondly, the histone acetylation and expression levels of TGFβRI were further detected in rat cartilage and human umbilical cord from IUGR individuals.

Results

Glycosaminoglycan content and the expression levels of chondrogenic genes were decreased in the WJ-MSCs from IUGR, and the expression levels of chondrogenic genes were further reduced after IL-1β treatment, while the expression levels of catabolic factors were increased. Then, serum cortisol level from IUGR individuals was found increased, and similar changes were observed in normal WJ-MSCs treated with excessive cortisol. Moreover, the decreased histone 3 lysine 9 acetylation (H3K9ac) level of TGFβRI and its expression were observed in IUGR-derived WJ-MSCs and normal WJ-MSCs treated with excessive cortisol, which could be abolished by RU486 and LMK235. At last, the decreased H3K9ac level of TGFβRI and its expression were further confirmed in the cartilage of IUGR rat offspring and human umbilical cords from IUGR newborn.

Conclusions

WJ-MSCs from IUGR individuals displayed a poor capacity of chondrogenic differentiation and an increased susceptibility to osteoarthritis-like phenotype, which was attributed to the decreased H3K9ac level of TGFβRI and its expression induced by high cortisol through GR/HDAC4. The H3K9ac of TGFβRI in human umbilical cord could be a potential early-warning biomarker for predicting neonatal cartilage dysplasia and osteoarthritis susceptibility.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02234-8.

Causal Association of Coffee Consumption and Total, Knee, Hip and Self-Reported Osteoarthritis: A Mendelian Randomization Study

BACKGROUND

The causal association between coffee consumption and the risk of OA is limited. This study was conducted to identify the potential causal effects of coffee consumption on total, knee, hip, and self-reported OA.

METHODS

Genome-wide association studies (GWAS) of OA were derived from the UK Biobank, comprising 50,508 participants of European ancestry (10,083 with cases and 40,425 controls), and genetic data for specific diagnosed knee OA (4462 cases and 17,885 controls), hip OA (12,625 cases and 50,898 controls), and self-reported OA (12,658 cases and 50,898 controls). Primary and secondary genetic instruments (11 SNPs and 8 SNPs) were selected as instrumental variants from GWAS among 375,833 and 91,462 participants. Two-sample Mendelian randomization (MR) analyses were performed to test the effects of the selected single nucleotide polymorphisms (SNPs) and the OA risk. The causal effects were primarily estimated using weighted median and inverse-variance weighted method with several sensitivity analyses.

RESULTS

The MR analyses suggested that genetically predicted 1% increase of coffee consumption was associated with an increased risk of overall OA (OR:1.009, 95% CI:1.003-1.016), knee OA (OR:1.023, 95% CI:1.009-1.038), self-reported OA (OR:1.007, 95% CI:1.003-1.011), but not hip OA (OR: 1.012, 95%CI:0.999-1.024) using primary genetic instruments. Similar results were found when using secondary genetic instruments that genetically predicted coffee consumption (cups/day). Additionally, the sensitivity analyses for leave-one-out methods supported a robust association between exposure traits and OA.

CONCLUSION

Our findings indicate that genetically predicted coffee consumption exerts a causal effect on total, knee, and self-reported OA risk, but not at the hip. Further research is required to unravel the role of coffee consumption in OA prevention.

Articular damages in multi-generational female offspring due to prenatal caffeine exposure correlates with H3K9 deacetylation of TGFβ signaling pathway

Adverse environment during pregnancy could lead to maternal glucocorticoid overexposure in utero, and then induce the intrauterine growth retardation (IUGR) and the programmed change in cartilage development. The transforming growth factor β (TGFβ) signaling pathway plays a crucial role in the process of chondrogenesis, cartilage growth, development, maturation, and phenotype maintenance. Our previous results had shown that prenatal caffeine exposure (PCE) could result in the damaged articular cartilage in offspring rats. However, whether this change could transmit to multiple generations was still unknown. In this study, pregnant Wistar rats received either saline or caffeine (120 mg/kg, i.g.) once daily from gestational day 9-20 (GD9-20). The female offspring mated with normal male rats to generate the following generations. We obtained the articular cartilages in subsequent F1 to F3 female offspring. The H3K9 acetylation and expression of the TGFβ signaling pathway were detected; the content of the cartilage matrix was detected. The results showed that PCE reduced the H3K9 acetylation and the expression of the TGFβ signaling pathway, then reduced the extracellular matrix in F1, F2, and F3 generations. in vitro, corticosterone could induce the H3K9 deacetylation of the TGFβ signaling pathway, thus inhibiting the expression of the TGFβ signaling pathway and extracellular matrix. The overall results revealed that PCE induced a multi-generational damaged articular cartilage in female offspring rats, which was partially related to the maternal high glucocorticoid-induced H3K9 hypoacetylation of TGFβ signaling pathway.

Ryanodine receptor 1 mediated dexamethasone-induced chondrodysplasia in fetal rats

BACKGROUND

Osteoarthritis is caused by cartilage dysplasia and has fetal origin. Prenatal dexamethasone exposure (PDE) induced chondrodysplasia in fetal rats by inhibiting transforming growth factor β (TGFβ) signaling. This study aimed to determine the effect of dexamethasone on fetal cartilage development and illustrate the underlying molecular mechanism.

METHODS

Dexamethasone (0.2 mg/kg.d) was injected subcutaneously every morning in pregnant rats from gestational day (GD) 9 to GD21. Harvested fetal femurs and tibias at GD21 for immunofluorescence and gene expression analysis. Fetal chondrocytes were treated with dexamethasone (100, 250 and 500 nM), endoplasmic reticulum stress (ERS) inhibitor, and ryanodine receptor 1 (RYR1) antagonist for subsequent analyses.

RESULTS

In vivo, prenatal dexamethasone exposure (PDE) decreased the total length of the fetal cartilage, the proportion of the proliferation area and the cell density and matrix content in fetal articular cartilage. Moreover, PDE increased RYR1 expression and intracellular calcium levels and elevated the expression of ERS-related genes, while downregulated the TGFβ signaling pathway and extracellular matrix (ECM) synthesis in fetal chondrocytes. In vitro, we verified dexamethasone significantly decreased ECM synthesis through activating RYR 1 mediated-ERS.

CONCLUSIONS

PDE inhibited TGFβ signaling pathway and matrix synthesis through RYR1 / intracellular calcium mediated ERS, which ultimately led to fetal dysplasia. This study confirmed the molecular mechanism of ERS involved in the developmental toxicity of dexamethasone and suggested that RYR1 may be an early intervention target for fetal-derived adult osteoarthritis.

Caffeine, a Risk Factor for Osteoarthritis and Longitudinal Bone Growth Inhibition

Osteoarthritis (OA), the most common chronic rheumatic disease, is mainly characterized by a progressive degradation of the hyaline articular cartilage, which is essential for correct joint function, lubrication, and resistance. Articular cartilage disturbances lead to joint failure, pain, and disability. Hyaline cartilage is also present in the growth plate and plays a key role in longitudinal bone growth. Alterations of this cartilage by diverse pathologies have been related to longitudinal bone growth inhibition (LBGI), which leads to growth retardation. Diet can play a crucial role in processes involved in the OA and LBGI's onset and evolution. Specifically, there is ample evidence pointing to the negative impacts of caffeine consumption on hyaline cartilage. However, its effects on these tissues have not been reviewed. Accordingly, in this review, we summarize all current knowledge in the PubMed database about caffeine catabolic effects on articular and growth plate cartilage. Specifically, we focus on the correlation between OA and LBGI with caffeine prenatal or direct exposure. Overall, there is ample evidence indicating that caffeine intake negatively affects the physiology of both articular and growth plate cartilage, increasing consumers predisposition to suffer OA and LBGI. As a result, caffeine consumption should be avoided for these pathologies.

GR/HDAC2/TGFβR1 pathway contributes to prenatal caffeine induced-osteoarthritis susceptibility in male adult offspring rats

Prenatal caffeine exposure (PCE) induces developmental toxicity of multi-organ and susceptibility to multi-disease in offspring. However, the effects of PCE on osteoarthritis susceptibility in adult offspring and its intrauterine programming mechanism remain to be further investigated. Here, we found that PCE induced susceptibility to osteoarthritis in male adult offspring rats, which was related to the inhibited function of cartilage matrix synthesis from fetuses to adults. Meanwhile, PCE consistently downregulated the H3K9ac and expression levels of transforming growth factor β receptor 1 (TGFβR1), and then blocked TGFβ signaling pathway, which contributed to the suppressed cartilage matrix synthesis. Moreover, the high level of corticosterone caused by PCE reduced the H3K9ac level on TGFβR1 promoter region through acting on glucocorticoids receptor (GR) and recruiting histone deacetylase 2 (HDAC2) into the nucleus of fetal chondrocytes. Taken together, PCE induced osteoarthritis susceptibility in male adult offspring rats, which was attributed to the low-functional programming of TGFβR1 induced by corticosterone via GR/HDAC2 signaling.

Metabolic Response of Adult Male Offspring Rats to Prenatal Caffeine Exposure

Caffeine is the most widely consumed psychoactive substance, with recommendations from health associations and regulatory bodies for limiting caffeine consumption during pregnancy being increasingly common. Prenatal exposure to caffeine has been shown to increase the risk of developing abnormalities in lipid metabolism in adult life. We further investigated the effect of prenatal caffeine exposure (PCE) (20 mg/kg of body weight) on the metabolic "reserve" of male Sprague Dawley offspring fed on a high fructose diet in adult life. Male adult PCE offspring were assigned to four groups; Nw and Nf: offspring of control mothers (N group of mothers), having received tap water or high fructose water respectively; Cw and Cf: offspring exposed to caffeine during gestation (C group of mothers) and receiving tap water or a high fructose water solution, respectively. Cf rats presented increased serum triglyceride level, as well as raised systolic and diastolic blood pressure levels, together with extensive renal tissue oedema in adulthood, compared to the other groups (p<0.05 for all comparisons). These findings show further evidence for potential detrimental metabolic effects of prenatal caffeine exposure during adulthood in this animal model.

Adenosinergic signalling in chondrogenesis and cartilage homeostasis: Friend or foe?

Chondrocytes and their mesenchymal cell progenitors secrete a variety of bioactive molecules, including adenine nucleotides and nucleosides, but these molecules are not usually highlighted in review papers about the secretome of these cells. Ageing and inflammatory insults compromise chondrocytes ability to keep ATP/adenosine synthesis, release and turnover. Cartilage homeostasis depends on extracellular adenosine levels, which acting via four P1 purinoceptor subtypes modulates the release of pro-inflammatory mediators, including NO, PGE₂ and several cytokines. Native articular cartilage is challenged by synovial fluid flow during normal joint motion transiently increasing ATP release and adenosine formation in the joint microenvironment. Excessive joint motion and shockwave trauma are deleterious to cartilage homeostasis due to HIF-1α overexpression, resulting in disproportionate ecto-5'-nucleotidase/CD73 production, adenosine accumulation and superfluous A_2B receptors activation. Scarcity of data however exists on the putative interplay between coexistent high affinity (A_2A and A₃) and low affinity (A_2B) adenosine receptors activation affecting stem cells fate towards preferential chondrogenic or osteogenic lineages in the human cartilage. Hints gathered in this commentary result mainly from studies using human immortalized cell lines and animal (e.g. rodent, equine, bovine) tissue samples. The available data point towards adenosine A_2A and A₃ receptors having cartilage protective roles, while excessive adenosine accumulation may be detrimental via low affinity A_2B receptors activation, with little reference to the putative role of the adenosine forming enzyme ecto-5'-nucleotidase/CD73. Thus, emphasizing the multiple pathways responsible for controlling adenosine signalling in cartilage will certainly impact on the search for novel therapeutic targets for highly disabling articular disorders.

Subchondral bone dysplasia mediates susceptibility to osteoarthritis in female adult offspring rats induced by prenatal caffeine exposure

Our previous studies confirmed that prenatal caffeine exposure (PCE) could induce susceptibility to osteoarthritis in adult offspring rats due to poor chondrocyte differentiation, but its mechanism remains to be further investigated. This study aimed to explore whether subchondral bone dysplasia mediates susceptibility to osteoarthritis in adult offspring rats induced by PCE. Pregnant Wistar rats were treated with caffeine (120 mg/kg.d) or saline from gestational day (GD) 9 to 20. The female offspring were euthanized to collect femurs at GD20, postnatal week (PW) 6, and PW28 (non-ovariectomy and ovariectomy groups) to detect osteoarthritis-like phenotype, subchondral bone mass, ossification center development, and other evidence. The results showed that PCE increased the Mankin score of pathological articular cartilage, but decreased articular cartilage thickness and subchondral bone mass, which were more obvious after ovariectomy. Meanwhile, the correlation analysis results demonstrated that the Mankin score of articular cartilage was significantly negatively correlated with subchondral bone mass, and the thickness of articular cartilage was significantly positively correlated with subchondral bone mass. Further, the length and area of the primary and secondary ossification centers, the number of osteoblasts, and the related genes' expression of osteogenic differentiation (e.g., Runx2, BSP, ALP, and OCN) were all significantly decreased in the PCE group before and after birth. Taken together, PCE induced susceptibility to osteoarthritis in adult female offspring, which was likely related to the subchondral bone dysplasia and reduction of subchondral bone mass production due to developmental disorder of primary and secondary ossification centers caused by osteoblast differentiation disability before and after birth.

Programming changes in GLUT1 mediated the accumulation of AGEs and matrix degradation in the articular cartilage of female adult rats after prenatal caffeine exposure

Osteoarthritis is associated with intrauterine growth retardation (IUGR) and abnormal glucose metabolism. Our laboratory previously reported that prenatal caffeine exposure (PCE) can induce intrauterine maternal glucocorticoid (GC) overexposure in IUGR offspring and increase susceptibility to osteoarthritis after birth. In the present study, we demonstrated the essential role of glucose transporter 1 (GLUT1) programming changes in the increased matrix degradation of articular cartilage and susceptibility to osteoarthritis in female PCE adult offspring. In vivo, we found that PCE decreased the matrix content but did not significantly change the expression of matrix degradation-related genes in the articular cartilage of female fetal rats. The decreased expression of IGF1 and GLUT1 and the content of advanced-glycation-end-products (AGEs) were also detected. At different postnatal stages (2, 6, and 12 weeks), the cartilage matrix content decreased while the degradation-related genes expression increased in the PCE group. Meanwhile, the expression of IGF1 and GLUT1 and AGEs content in the local cartilage increased. In vitro, the expression levels of IGF1 and GLUT1 were inhibited by corticosterone but remained unchanged under caffeine treatment. Exogenous IGF1 can reverse the corticosterone-induced decrease in GLUT1 expression and promote AGEs production, while mifepristone (a glucocorticoid receptor inhibitor) reversed the corticosterone-induced low expression of IGF1 and GLUT1. Exogenous AGEs can increase the expression of inflammatory factors (IL-6 and TNF-α) and degradation-related genes, and decrease the matrix synthesis-related genes expression in chondrocyte. In conclusion, the GC-IGF1-GLUT1 axis mediated intrauterine dysplasia of articular cartilage, increased accumulation of AGEs and matrix degradation after birth in PCE female offspring, thereby increasing their susceptibility to osteoarthritis in adulthood.

Developmental origins of type 2 diabetes: Focus on epigenetics

Traditionally, genetics and lifestyle are considered as main determinants of aging-associated pathological conditions. Accumulating evidence, however, suggests that risk of many age-related diseases is not only determined by genetic and adult lifestyle factors but also by factors acting during early development. Type 2 diabetes (T2D), an age-related disease generally manifested after the age of 40, is among such disorders. Since several age-related conditions, such as pro-inflammatory states, are characteristic of both T2D and aging, this disease is conceptualized by many authors as a kind of premature or accelerated aging. There is substantial evidence that intrauterine growth restriction (IUGR), induced by poor or unbalanced nutrient intake, exposure to xenobiotics, maternal substance abuse etc., may impair fetal development, thereby causing the fetal adipose tissue and pancreatic beta cell dysfunction. Consequently, persisting adaptive changes may occur in the glucose-insulin metabolism, including reduced capacity for insulin secretion and insulin resistance. These changes can lead to an improved ability to store fat, thus predisposing to T2D development in later life. The modulation of epigenetic regulation of gene expression likely plays a central role in linking the adverse environmental conditions early in life to the risk of T2D in adulthood. In animal models of IUGR, long-term persistent changes in both DNA methylation and expression of genes implicated in metabolic processes have been repeatedly reported. Findings from human studies confirming the role of epigenetic mechanisms in linking early-life adverse experiences to the risk for T2D in adult life are scarce compared to data from animal studies, mainly because of limited access to suitable biological samples. It is, however, convincing evidence that these mechanisms may also operate in human beings. In this review, theoretical models and research findings evidencing the role of developmental epigenetic variation in the pathogenesis of T2D are summarized and discussed.

Decreased H3K9ac level of KLF4 mediates podocyte developmental toxicity induced by prenatal caffeine exposure in male offspring rats

This study aimed to verify the toxic effects of prenatal caffeine exposure (PCE) on the podocyte development in male offspring, and to explore the underlying intrauterine programming mechanisms. The pregnant rats were administered with caffeine (30 to 120 mg/kg⋅d) during gestational day (GD) 9 to 20. The male fetus on GD20 and the offspring at postnatal week (PW) 6 and PW28 were sacrificed. The results indicated that PCE caused ultrastructural abnormalities on podocyte, and inhibited the expression of podocyte marker genes such as Nephrin, Wilms tumor 1 (WT1), the histone 3 lysine 9 acetylation (H3K9ac) level in the Kruppel-like factor 4 (KLF4) promoter and its expression in the male offspring from GD20 to PW28. Meanwhile, the expression of glucocorticoid receptor (GR) and histone deacetylase 7 (HDAC7) in the fetus were increased by PCE. In vitro, corticosterone increased GR and HDAC7 whereas reduced the H3K9ac level of KLF4 and KLF4/Nephrin expression. KLF4 over-expression reversed the reduction of Nephrin expression, knockdown of HDAC7 and GR antagonist RU486 partially reversed the inhibitory effects of corticosterone on H3K9ac level and KLF4 expression. In conclusion, PCE caused podocyte developmental toxicity in male offspring, which was associated with corticosterone-induced low-functional programming of KLF4 through GR/HDAC7/H3K9ac pathway.

Prenatal ethanol exposure-induced a low level of foetal blood cholesterol and its mechanism of IGF1-related placental cholesterol transport dysfunction

Clinical researches showed that intrauterine growth retardation (IUGR) foetus had decreased blood cholesterol levels. The present study aimed to confirm that prenatal ethanol exposure (PEE) caused decreased blood cholesterol levels in IUGR foetal rats and elucidate its placental mechanism. Pregnant Wistar rats were intragastrically administrated with ethanol (4 g/kg.d) on gestational days 9-20 (GD9-20). in vivo, PEE increased the levels of total cholesterol (TCH), high-density lipoprotein-cholesterol (HDL-C) and low-density lipoprotein-cholesterol (LDL-C) in maternal serum, whereas decreased them in both female and male foetal serum. Moreover, the expression of cholesterol transport genes, scavenger receptor class B type 1 (SCARB1), low-density lipoprotein receptor (LDLR), ATP binding cassette subfamily A member 1 (ABCA1) and ATP binding cassette subfamily G member 1 (ABCG1) was reduced in female and male placentas in the PEE group. Meanwhile, the proliferation decreased and the apoptosis increased in female and male placentas, and the insulin like growth factor 1 (IGF1) signal pathway was inhibited. in vitro, after being treated with ethanol (15, 30, 60, 120 mM) for 72 h, the expression of cholesterol transport genes was decreased, the apoptosis was increased, the proliferation was decreased and the IGF1 signal pathway was inhibited in BeWo cells, whereas exogenous IGF1 reversed these changes. In conclusion, by inhibiting the IGF1 signal pathway in placentas, PEE induced apoptosis and inhibited proliferation, thus decreased the cholesterol transport in placentas, and eventually leading to low blood cholesterol levels in foetal rats.

Intrauterine programming of the glucocorticoid-insulin-like growth factor 1 (GC-IGF1) axis mediates glomerulosclerosis in female adult offspring rats induced by prenatal ethanol exposure

Prenatal ethanol exposure (PEE) causes intrauterine growth retardation (IUGR), and the occurrence of glomerulosclerosis is closely related to IUGR. This study aimed to confirm the kidney toxic effect of PEE and explore its intrauterine programming mechanism in female offspring. The Wistar female fetuses on gestational day (GD) 20 and the adult offspring at postnatal week 24 were anesthetized and decapitated. The adult offspring kidneys in the PEE group displayed glomerular hyperplasia and glomerulosclerosis. Blood urea nitrogen (BUN) and the BUN / Serum creatinine (Scr) concentration ratio in the PEE group was increased significantly compared to the control group (P<0.01, P<0.05). Meanwhile, the renal glucocorticoid-activation system was inhibited, whereas the insulin-like growth factor 1 (IGF1) signaling pathway was activated in the female adult offspring of the PEE group. In the fetal kidney of the PEE group, pathological observation showed kidney dysplasia, and the gene expression of the glial-cell-line-derived neurotrophic factor/tyrosine kinase receptor (GDNF/c-Ret) signaling pathway was reduced compared to that of the control group. Moreover, the glucocorticoid-activation system was activated, whereas the IGF1 signaling pathway was inhibited in the fetal kidneys of the PEE group. In conclusion, PEE caused fetal kidney dysplasia and adult glomerulosclerosis in the female offspring rats, and the intrauterine programming alteration of glucocorticoid-insulin-like growth factor 1 (GC-IGF1) axis might be involved in fetal-originated glomerulosclerosis.

Caffeine programs hepatic SIRT1-related cholesterol synthesis and hypercholesterolemia via A2AR/cAMP/PKA pathway in adult male offspring rats

Clinical and animal studies have indicated that hypercholesterolemia has intrauterine developmental origin. Our previous studies showed that prenatal caffeine exposure (PCE) increased the serum total cholesterol (TCH) levels in adult offspring rats. This study investigates the intrauterine programming mechanism of PCE male offspring rats susceptible to adult hypercholesterolemia. Pregnant Wistar rats were intragastrically administered caffeine (30, 60, and 120 mg/kg∙d) from gestational days (GD) 9 to 20. Male offspring were sacrificed under anesthesia at GD20 and postnatal week (PW) 12, and the serum and liver were collected. The effects of caffeine (0-100 μM, 24 h) on the expression of cholesterol synthesis related genes and their epigenetic mechanisms were confirmed in L02 cells. The results showed that PCE induced higher levels of serum TCH, LDL-C and higher ratios of TCH/HDL-C and LDL-C/HDL-C. Furthermore, the high levels of histone acetylation (via H3K14ac and H3K27ac) and the expression of genes (Srebf2, Hmgcr, Hmgcs1) were responsible for cholesterol synthesis. The results of PCE offspring in utero and the data in vitro exhibited similar changes, and accompanied by the reduced expression of adenosine A2A receptor (A2AR), cyclic adenosine monophosphate (cAMP), sirtuin1 and protein kinase A (PKA). These changes could be reversed by A2AR agonist (CGS-21680), cAMP agonist (forskolin) and sirtuin1 agonist (resveratrol). Therefore, our results confirmed that caffeine could enhance histone acetylation and expression levels of genes responsible for cholesterol synthesis via inhibiting the A2AR/cAMP/PKA pathway and down-regulating sirtuin1, which continued throughout adulthood and elevated hepatic cholesterol synthesis and hypercholesterolemia in the male offspring rats.

Investigating the possible causal association of coffee consumption with osteoarthritis risk using a Mendelian randomization analysis

This study examined whether coffee consumption is causally associated with osteoarthritis. A two-sample Mendelian randomization (MR) analysis using inverse-variance weighted (IVW) and weighted median estimates, and the MR-Egger regression method were performed. The publicly available summary statistical datasets of coffee consumption genome-wide association studies (GWASs) meta-analyses on coffee intake from eight Caucasian cohorts (n = 18,176), GWAS meta-analyses of predominately regular-type coffee consumers of European ancestry (n = up to 91,462), and a GWAS in 7410 patients with osteoarthritis in the arcOGEN study with 11,009 controls of European ancestry were evaluated. Four single-nucleotide polymorphisms (SNPs) from GWASs of coffee consumption as instrumental variables (IVs) to improve inference were selected. These SNPs were located at neurocalcin delta (NCALD) (rs16868941), cytochrome p450 oxidoreductase (POR) (rs17685), cytochrome p450 family 1 subfamily A member 1 (CYP1A1) (rs2470893), and neuronal cell adhesion molecule (NRCAM) (rs382140). The IVW method (beta = 0.381, SE = 0.170, p = 0.025) and the weighted median approach (beta = 0.419, SE = 0.206, p = 0.047) showed evidence to support a causal association between coffee consumption and osteoarthritis. MR-Egger regression revealed that directional pleiotropy was unlikely to be biasing the result (intercept = 0.064; p = 0.549), but showed no causal association between coffee consumption and osteoarthritis (beta = - 0.518, SE = 1.270, p = 0.723). Cochran's Q test and the funnel plot indicated no evidence of heterogeneity between IV estimates based on the individual variants. The results of MR analysis support the observation that coffee consumption is causally associated with an increased risk of osteoarthritis.

Role of TGFβ Signaling in Maternal Ethanol-Induced Fetal Articular Cartilage Dysplasia and Adult Onset of Osteoarthritis in Male Rats

Based on our previous findings that prenatal ethanol exposure in offspring increased susceptibility to adult osteoarthritis, this study aimed to further investigate the direct toxicity of ethanol on fetal articular cartilage development. Rat bone marrow-derived stroma cells were capsulated in alginate beads, incubated in a chondrogenic differentiation medium, and cultured for 4 weeks with ethanol treatment at concentrations of 0, 4, 20, and 100 mM. Pregnant rats were treated with ethanol (4 g/kg/day) from gestational days (GDs) 9 to 20. At GD20 and postnatal weeks 2, 6, and 12, 8 male offspring were sacrificed, and 8 male offspring rats of 8-weeks old in each group were treated with or without intraarticular injection of papain for 4 weeks to verify the susceptibility of adult osteoarthritis. Ethanol treatment resulted in poor differentiation of bone marrow-derived stroma cells to chondrocytes and suppressed the expression of the transforming growth factor-β (TGFβ)-smad2/3-Sox9 signaling pathway. In animal experiments, the shape of articular cartilage in the ethanol treatment group was more disordered than that of the control group, the matrix was not deep, and the cartilage was thin, which showed poor cartilage development. The TGFβ signaling pathway in the ethanol treatment group was persistently low at all time points. After intraarticular injection of papain, histological analyses, and the Mankin score revealed increased cartilage destruction in the ethanol treatment group. Ethanol caused articular cartilage dysplasia that was programmed in adulthood via a low-functional TGFβ signaling pathway, and the tolerance of this articular cartilage to external stimuli was significantly decreased.

Prenatal caffeine exprosure increases adult female offspring rat's susceptibility to osteoarthritis via low-functional programming of cartilage IGF-1 with histone acetylation

Our previous in vivo studies showed that prenatal caffeine exposure (PCE) could restrain the development of chondrogenesis, which may delay fetal articular cartilage development and increase susceptibility to osteoarthritis in adults. So, the goal of the current study is to clarify theincreasing susceptibility to adult osteoarthritis in caffeine-exposed female offspring and its'mechanism. Pregnant rats were treated with 120 mg/kg·d caffeine or equal volumes of saline from gestational day (GD) 9 to 20. knee joints were collected from GD20 female fetuses and 18-week old female offspring which was treated with strenuous running for 6 weeks (55 min/day at 20 m/min) load to induce osteoarthritis. Knee joints from GD20 fetuses and adult offspring were collected for histochemistry and immunohistochemistry. Next, chondrocytes were isolated from 1-day-old newborn rats and in vitro studies were conducted where the cells in primary culture were exposed to 1, 10, and 100 μM caffeine and 250, 500, and 1,250 nM corticosterone. Insulin-like growth factor 1 (IGF-1) signal pathway genes' expression levels in fetal chondrocytes were studied, and IGF-1 histone acetylation was detected in vitro. Immunohistochemical results showed low expression levels of IGF-1 signaling genes (IGF-1, IRS-1, AKT, and COL2A1) both in fetal and adult cartilage with PCE. For adult offspring, histological results and Mankin score revealed increased cartilage destruction and accelerated osteoarthritis progression in PCE group with strenuous running exercise. Analysis in vitro revealed that caffeine and corticosterone impeded the expression of IGF-1 signaling pathway aggrecan and COL2A1 genes, but only corticosterone decreased H3K9 and H3K27 acetylation in the IGF-1 promoter region. In concluson, PCE low functional programmed cartilage IGF-1 by histone acetylation modification via overexposure to corticosterone and delayed articular cartilage development from fetus to adults. Then, the delayed cartilage development increased susceptibility to osteoarthritis in offsprings.

Intrauterine programming mechanism for hypercholesterolemia in prenatal caffeine-exposed female adult rat offspring

Clinical and animal studies have indicated that hypercholesterolemia and its associated diseases have intrauterine developmental origins. Our previous studies showed that prenatal caffeine exposure (PCE) led to fetal overexposure to maternal glucocorticoids (GCs) and increased serum total cholesterol levels in adult rat offspring. This study further confirms the intrauterine programming of PCE-induced hypercholesterolemia in female adult rat offspring. Pregnant Wistar rats were intragastrically administered caffeine (30, 60, and 120 mg/kg/d) from gestational day (GD)9 to 20. Female rat offspring were euthanized at GD20 and postnatal wk 12; several adult rat offspring were additionally subjected to ice-water swimming stimulation to induce chronic stress prior to death. The effects of GCs on cholesterol metabolism and epigenetic regulation were verified using the L02 cell line. The results showed that PCE induced hypercholesterolemia in adult offspring, which manifested as significantly higher levels of serum total cholesterol and LDL cholesterol (LDL-C) as well as higher ratios of LDL-C/HDL cholesterol. We further found that the cholesterol levels were increased in fetal livers but were decreased in fetal blood, accompanied by increased maternal blood cholesterol levels and reduced placental cholesterol transport. Furthermore, analysis of PCE offspring in the uterus and in a postnatal basal/chronic stress state and the results of in vitro experiments showed that hepatic cholesterol metabolism underwent GC-dependent changes and was associated with cholesterol synthase via abnormalities in 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR) histone acetylation. We concluded that, to compensate for intrauterine placentally derived decreases in fetal blood cholesterol levels, high intrauterine GC levels activated fetal hepatic CCAAT enhancer binding protein α signaling and down-regulated Sirtuin1 expression, which mediated the high levels of histone acetylation ( via H3K9ac and H3K14ac) and expression of HMGCR. This GC-dependent cholesterol metabolism programming effect was sustained through adulthood, leading to the occurrence of hypercholesterolemia.-Xu, D., Luo, H. W., Hu, W., Hu, S. W., Yuan, C., Wang, G. H., Zhang, L., Yu, H., Magdalou, J., Chen, L. B., Wang, H. Intrauterine programming mechanism for hypercholesterolemia in prenatal caffeine-exposed female adult rat offspring.

Glucocorticoid mediates prenatal caffeine exposure-induced endochondral ossification retardation and its molecular mechanism in female fetal rats

Our previous studies discovered that prenatal caffeine exposure (PCE) could induce intrauterine growth retardation (IUGR) and long-bone dysplasia in offspring rats, accompanied by maternal glucocorticoid over-exposure. This study is to explore whether intrauterine high glucocorticoid level can cause endochondral ossification retardation and clarify its molecular mechanism in PCE fetal rats. Pregnant Wistar rats were intragastrically administered 30 and 120 mg/kg day of caffeine during gestational days (GDs) 9–20, then collected fetal serum and femurs at GD20. In vitro, primary chondrocytes were treated with corticosterone (0–1250 nM), caffeine (0–100 μM), mitogen-inducible gene 6 (Mig-6) siRNA and epidermal growth factor receptor (EGFR) siRNA, respectively, or together. Results showed that the hypertrophic chondrocytes zone (HZ) of PCE fetal femur was widened. Meanwhile, the expression levels of chondrocytes terminal differentiation genes in the HZ were decreased, and the chondrocytes apoptosis rate in the HZ was decreased too. Furthermore, PCE upregulated Mig-6 and suppressed EGFR expression in the HZ. In vitro, a high-concentration corticosterone (1250 nM) upregulated Mig-6 expression, inhibit EGFR/c-Jun N-terminal kinase (JNK) signaling pathway and terminal differentiation genes expression in chondrocytes and reduced cell apoptosis, and these above alterations could be partly reversed step-by-step after Mig-6 and EGFR knockdown. However, caffeine concentration dependently increased chondrocyte apoptosis without significant changes in the expression of terminal differentiation genes. Collectively, PCE caused endochondral ossification retardation in the female fetal rats, and its main mechanism was associated with glucocorticoid (rather than caffeine)-mediated chondrocyte terminal differentiation suppression by the upregulation of Mig-6 and then inhibition of EGFR/JNK pathway-mediated chondrocyte apoptosis.