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:Hyaluronan receptor LYVE-1 is expressed by liver sinusoidal endothelial cells (LSEC), lymphatic endothelial cells and specialized macrophages. Besides binding hyaluronan, LYVE-1 mediates adhesion of leukocytes and cancer cells to endothelial cells. Here, we analyzed the impact of LYVE-1 on physiological liver functions and metastasis. Mice with deficiency of Lyve-1 (Lyve-1 KO) were analyzed using histology, immunofluorescence, RNA sequencing, plasma proteomics and flow cytometry. Liver metastasis was studied by intrasplenic/intravenous injection of melanoma (B16F10luc2, WT31) or colorectal carcinoma (MC38) cell lines. Results: Hepatic architecture, liver size, endothelial differentiation and angiocrine functions were unaltered in Lyve-1 KO mice. Hyaluronan plasma levels were significantly increased in Lyve-1-KO mice; besides, plasma proteomics revealed increased carbonic anhydrase-2 and decreased FXIIIA, potential modulators of metastatis. Furthermore, gene expression analysis of LSEC indicated regulation of immunological pathways. Therefore, liver metastasis of a highly and of a weekly immunogenic tumor, i.e. melanoma and colorectal carcinoma (CRC), was analyzed in Lyve-1 KO mice. Hepatic metastasis of B16F10 luc2 and WT31 melanoma cells, but not MC38 CRC cells, was significantly reduced in Lyve-1 KO mice. While short-term adhesion assays with B16F10 luc2 cells in vivo did not show differences between Lyve-1 KO and wild-type mice, increased numbers of resident hepatic CD4+, CD8+ and regulatory T cells were detected in Lyve-1 KO livers. In addition, iron deposition was detected in F4/80+ liver macrophages known to exert pro-inflammatory effects. Conclusions: LYVE-1 deficiency controlled hepatic metastasis in a tumor cell-specific manner reducing hepatic metastasis of melanoma, but not CRC. Anti-tumorigenic effects are likely due to enhancement of the resident hepatic immune microenvironment.
Project description:The cleavage of sphingoid base phosphates by sphingosine-1-phosphate (S1P) lyase to produce phosphoethanolamine and a fatty aldehyde is the final degradative step in the sphingolipid metabolic pathway. We have studied mice with an inactive S1P lyase gene and have found that, in addition to the expected increase of sphingoid base phosphates, other sphingolipids (including sphingosine, ceramide, and sphingomyelin) were substantially elevated in the serum and /or liver of these mice. This latter increase is consistent with a reutilization of the sphingosine backbone for sphingolipid synthesis due to its inability to exit the sphingolipid metabolic pathway. Furthermore, the S1P lyase deficiency resulted in changes in the levels of serum and liver lipids not directly within the sphingolipid pathway, including phospholipids, triacyglycerol, diacylglycerol, and cholesterol. Even though lipids in serum and lipid storage were elevated in liver, adiposity was reduced in the S1P lyase-deficient mice. Microarray analysis of lipid metabolism genes in liver showed that the S1P lyase deficiency caused widespread changes in their expression pattern. These results demonstrate that S1P lyase is a key regulator of the levels of multiple sphingolipid substrates and reveal functional links between the sphingolipid metabolic pathway and other lipid metabolic pathways that may be mediated by shared lipid substrates and changes in gene expression programs. The disturbance of lipid homeostasis by altered sphingolipid levels may be relevant to metabolic diseases. Experiment Overall Design: RNA samples from liver for three sphingosine-1-phosphate lyase knock-out and three WT mice.
Project description:The cell-specific role of lysosomal protease cathepsin D (CtsD) in liver fibrosis is not completely clear. This study reports that while CtsD is highly expressed in liver macrophages of cirrhotic patients, CtsD deletion in macrophages resulted in enhanced liver fibrosis. For this scope, a macrophage-CtsD knock-out mouse (CtsDMac) model was generated. Livers obtained from the mouse model and from its control were analyzed by shotgun label-free quantitative (LFQ) proteomics.