Project description:Malnutrition during pregnancy, which causes prenatal exposure to excessive glucocorticoid, induces adverse metabolic programming leading to hypertension in offspring. Pregnant rats receiving a low-protein diet exhibited moderate downregulation of 11-beta-dehydrogenase isozyme 2, which inactivates corticosterone, in the placenta, resulting in prenatal exposure to excessive corticosterone. In offspring of pregnant rats receiving a low-protein diet or dexamethasone, mRNA expression of angiotensin receptor type 1a (Agtr1a) in the paraventricular nucleus (PVN) of the hypothalamus was upregulated, concurrent with reduced expression of DNA methyltransferase 3a (Dnmt3a), reduced binding of DNMT3a to the Agtr1a promoter, and DNA demethylation, suggesting hypothalamic Agtr1a expression is epigenetically modulated by excess glucocorticoid. Dexamethasone treatment of PVN cells downregulated DNMT3a while upregulating Agtr1a, and decreased DNMT3a binding and DNA demethylation at the Agtr1a promoter. Consistent with Agtr1a upregulation in the hypothalamus, salt loading increased BP in both types of offspring. Even without dexamethasone treatment, hypothalamic neuron-specific DNMT3a-deficient mice, in which Agtr1a was upregulated, exhibited salt-induced BP elevation. By contrast, dexamethasone-treated Agtr1a-deficient mice failed to show salt-induced BP elevation, despite reduced expression of DNMT3a. Thus, epigenetic modulation of hypothalamic angiotensin signaling contributes to salt-sensitive hypertension induced by prenatal glucocorticoid excess in offspring of mothers that are malnourished during pregnancy.
Project description:Purpose: Cholestatic liver injury is associated with intrahepatic biliary fibrosis, which can progress to cirrhosis. Resident hepatic progenitor cells (HPCs) expressing Prominin-1 (Prom1/CD133) become activated and participate in the expansion of cholangiocytes known as the ductular reaction. Previously, we demonstrated that in biliary atresia, Prom1(+) HPCs are present within developing fibrosis and that null mutation of Prom1 significantly abrogates fibrogenesis. Here, we hypothesized that these activated Prom1-expressing HPCs promote fibrogenesis in cholestatic liver injury. Methods: Using Prom1CreERT2-nLacZ/+;Rosa26Lsl-GFP/+ mice, we traced the fate of Prom1-expressing HPCs in the growth of the neonatal and adult livers and in biliary fibrosis induced by bile duct ligation (BDL). Results: Prom1-expressing cell lineage labeling with Green Fluorescent Protein (GFP) on postnatal day 1 exhibited an expanded population as well as bipotent differentiation potential towards both hepatocytes and cholangiocytes at postnatal day 35. However, in the adult liver, they lost hepatocyte differentiation potential. Upon cholestatic liver injury, adult Prom1-expressing HPCs gave rise to both PROM1(+) and PROM1(-) cholangiocytes contributing to ductular reaction without hepatocyte or myofibroblast differentiation. RNA-sequencing analysis of GFP(+) Prom1-expressing HPC lineage revealed a persistent cholangiocyte phenotype and evidence of Transforming Growth Factor-b pathway activation. Conclusion: Our data indicate that Prom1-expressing HPCs promote biliary fibrosis by activation of myofibroblasts in cholestatic liver injury.
Project description:In this study, we aimed to unravel the transcriptional profiles of specific hepatic macrophage subsets during cholestatic liver injury, acute colitis and when colitis is induced as a second hit on advanced cholestatic liver injury. Differentially expressed genes (DEGs) and corresponding pathways were determined via DESeq2 in R and STRING-App comparing groups or cell types as outlined in the 'overall design' section below. Our results highlight the heterogeneity of the liver macrophage (MF) pool and describe functional differences between MF subsets. Longitudinally, the CBDL-associated expression profiles of each macrophage subset remained mostly stable. CBDL-induced cholestatic liver injury was characterized by the emergence of Trem2/Spp1 expressing monocyte-derived macrophages (MoMFs). DSS-colitis as a second hit on cholestatic liver injury enhanced this phenotype of MoMFs.
Project description:Bile acid accumulation and subsequent liver damage is a frequent adverse effect induced by drugs. Considerable efforts have therefore been focused on the introduction and characterization of tools that allow reliable prediction of this type of drug-induced liver injury. Among those are the cholestatic index and transcriptomic profiling, which are typically assessed in in vitro settings. The present study was set up to test the applicability of both tools to non-pharmaceutical compounds with cholestatic potential, including the industrial compound bis(2-ethylhexyl)phthalate, the cosmetic ingredients triclosan and octynoic acid, the herbicides paraquat and quizalofop-para-ethyl, and the food additives sunset yellow and tartrazine, in a human hepatoma cell culture model of cholestatic liver injury. The cholestatic index method showed cholestatic liability of sunset yellow, tartrazine and triclosan. Of those, tartrazine induced transcriptional changes reminiscent of the transcriptional profile of cholestatic drugs. Furthermore, a number of genes were found to be uniquely modulated by tartrazine, in accordance with the cholestatic drugs atazanavir, cyclosporin A and nefazodone, which may have potential as novel transcriptomic biomarkers of chemical-induced cholestatic liver injury. In conclusion, unambiguous identification of the non-pharmaceutical compounds tested in this study as inducers of cholestasis could not be achieved.
Project description:Vitamin D, a fat-soluble vitamin, plays a critical role in calcium homeostasis, the immune system, and normal development. Many epidemiological cohort studies globally have found high prevalence rates of vitamin D deficiency and insufficiency, recognized as an important health issue that needs to be solved. In particular, reproductive age and pregnant women low in vitamin D status may confer risks of diseases like obesity on their offspring. While observational studies have suggested associations between prenatal vitamin D deficiency and metabolic phenotypes in offspring, not yet determined is whether prenatal vitamin D deficiency permanently alters the development of the liver, a major metabolic organ. We tested the histopathology and the transcriptomic profiles of livers from male C57BL/6J mice exposed to prenatal vitamin D deficiency through a maternal dietary intervention model. We found that prenatal vitamin D deficiency increases the prevalence of histopathological changes in the liver, and alters its gene expression profile. Cell subtype proportion analysis showed that the liver of prenatal vitamin D deficiency alters non-parenchymal cells of the liver, specifically macrophages, a subset of endothelial cells, and dendritic cells. Our results indicate the long-term memory of prenatal vitamin D deficiency exposure in the adult liver, a potential contributor to offspring health risks.
Project description:Cholestasis is characterized by hepatic accumulation of cytotoxic bile acids (BAs), which often subsequentlyleads to liver injury, inflammation, fibrosis, and ultimately liver cirrhosis. Fibroblast growth factor 21 (FGF21) is a liver secreted hormone with pleiotropic effects on the homeostasis of glucose, lipid, and energy metabolism. However, whether hepatic FGF21 plays a role in cholestatic liver injury remains elusive. We found that serum and hepatic FGF21 levels were significantly increased in response to cholestatic liver injury. Hepatocyte-specific deletion of Fgf21 exacerbated hepatic accumulation of BAs, further accentuating liver injury. Consistently, administration of rFGF21 ameliorated cholestatic liver injury in α-naphthylisothiocyanate (ANIT)-treated and Mdr2 deficiency mice. Mechanically, FGF21 activated a hepatic FGFR4-JNK signaling pathway to decrease Cyp7a1 expression, thereby reducing hepatic BAs pool. Our study demonstrates that hepatic FGF21 functions as an adaptive stress-responsive signal to downregulate BA biosynthesis, thereby ameliorating cholestatic liver injury, and FGF21 analogs may represent a candidate therapy for cholestatic liver diseases.
Project description:Ductular reactive (DR) cells exacerbate cholestatic liver injury and fibrosis. In this study we posited that tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) emanating from recruited macrophages restrains DR cell expansion by apoptosis, thereby limiting cholestatic liver injury. Cholestatic liver injury was induced in Wild type (WT), Trailfl/fl and in myeloid-specific Trail deleted (TrailΔmye) C57BL/6 mice using the DDC diet. The DDC diet induced injury and hepatomegaly. However, parameters of liver injury, fibrosis, ductular reaction and inflammation were all increased in the TrailΔmye mice as compared to the WT and Trailfl/fl mice. To better resolve the gene expression profile of cholangiocytes that may promote the recruitment of myeloid cells into the periportal neighborhood, we performed spatial transcriptomics on FPPE liver tissue sections from WT and TrailΔmye mice that were fed the control or DDC diet using the NanoString GeoMx DSP platform (Cat. No. 121401103, GeoMx NGS RNA WTA Mm).
Project description:Prenatal dexamethasone exposure (PDE) has long-term consequences in bone development. we investigated how PDE exerts persistent effect on bone metabolism in mouse offspring. Our results showed that PDE offspring exhibited reduced bone mass, fewer osteoblasts and diminished osteoprogenitors proliferation.And PDE increased MKP-1 expression, while decreasing H3 lysine 9 dimethylation (H3K9me2) at Mkp-1 gene locus. Mechanistically, dexamethasone suppressed osteoprogenitors proliferation by upregulating MKP-1 expression, notably through the inhibition of H3K9me2 modifications, which promoted demethylation and transcriptional activation of the Mkp-1 gene. Importantly, restoring histone methylation balance with PFI-90 treatment blocked the inhibitory effects of PDE on MAPK signaling in osteoprogenitors, and mitigated the detrimental impact of PDE on osteoprogenitor proliferation and bone development in the offspring. Therefore,we performed ChIP-seq for H3K9me2 to identify its role in related epigenetic changes.
Project description:Background and aims: Signal transducer and activator of transcription 3 (Stat3) is the main mediator of interleukin-6 type cytokine signaling required for hepatocyte proliferation and hepatoprotection but its role in sclerosing cholangitis (SC) and other cholestatic liver diseases remains unresolved. Methods: We investigated the role of Stat3 in inflammation-induced cholestatic liver injury and used mice lacking the multidrug resistance gene 2 (mdr2-/-) as a model for SC. Results: We demonstrate that conditional inactivation of stat3 in hepatocytes and cholangiocytes (stat3Δhc) of mdr2-/- mice strongly aggravated bile acid-induced liver injury and fibrosis. Similarly, stat3Δhc mice are more sensitive to cholic acid feeding than control mice. Global gene expression analysis demonstrated that hepatoprotective signals via epidermal growth factor and insulin-like growth factor 1 are affected upon loss of Stat3. Conclusions: Our data suggest that Stat3 protects cholangiocytes and hepatocytes from bile acid-induced damage thereby preventing liver fibrosis in cholestatic diseases.
Project description:Based on the developmental origin of health of disease hypothesis, we previously showed that prenatal 70% maternal food restriction (FR30) predisposes the offspring to development of pathologies in adulthood. In the present study, we focused on the liver gene expression profile of standard and high fat (HF)-fed FR30 adult offspring.