Project description:Pharmacological inhibition of megalin (also known as low-density lipoprotein receptor-related protein 2: LRP2) attenuates atherosclerosis in hypercholesterolemic mice. Since megalin is abundant in renal proximal tubule cells (PTCs), PTC-LRP2 +/+ and -/- littermates in an LDL receptor -/- background were generated and fed a Western diet to determine effects of PTC-derived megalin on atherosclerosis. PTC-specific megalin deletion did not attenuate atherosclerosis in LDL receptor -/- mice in either sex. Serendipitously, we discovered that PTC-specific megalin deletion led to interstitial infiltration of CD68+ cells and tubular atrophy. The pathology was only evident in male PTC-LRP2 -/- mice fed the Western diet, but not in mice fed a normal laboratory diet. Renal pathologies were also observed in male PTC-LRP2 -/- mice in an LDL receptor +/+ background fed the same Western diet, demonstrating that the renal pathologies were dependent on diet and not hypercholesterolemia. By contrast, female PTC-LRP2 -/- mice had no apparent renal pathologies. In vivo multiphoton microscopy demonstrated that PTC-specific megalin deletion dramatically diminished albumin accumulation in PTCs within 10 days of Western diet feeding. RNA sequencing analyses demonstrated the upregulation of inflammation-related pathways in kidney. Overall, PTC-specific megalin deletion leads to tubulointerstitial nephritis in mice fed Western diet, with severe pathologies in male mice.
Project description:Hepatic transcriptome of junctional adhesion molecule A knockout, F11r–/– mice fed a Western diet (WD) for eight weeks. A cohort of WD-fed mice were treated with IgG or α4β7 mAb for four weeks starting at week four following initiation of the WD.
Project description:SHP (small heterodimer partner; NR0B2) belongs to the nuclear hormone receptor superfamily, which regulates numerous developmental and metabolic cellular functions. To study physiological function of SHP, we generated congenic SHP-/- mice on C57Bl/6 background. When the congenic SHP-/- mice were challenged with a western diet (harlan, TD.88137) for 22 weeks, they were resistant to diet induced obesity and hepatic steatosis compared to WT controls. However, their hepatic insulin sensitivity was compromised when assessed with phospho-Akt levels after insulin injection. Therefore, we investigated hepatic gene expression using illumina beadchip array to explore mechanisms underneath the unique liver physiology in SHP-/- mice. Livers were collected from C57Bl/6 wild type and C57Bl/6 SHP-/- mice fed chow or western diet. The 1 microgram of total RNA obtained from individual mouse (n=4 per group) and subjected to illumina beadchip gene expression profiling.
Project description:LV hypertrophy is associated with Western diet consumption, while intake of n-3 polyunsaturated fatty acids is associated with anti-hypertrophic effects. We treated rats for 12 weeks with either a Control diet, a Western diet or a Western + DHA diet. For each of the 3 dietary treatments there were 2 pooled samples of heart tissue (with each pooled sample representing 5 rats) for a total of 6 arrays. Microarray analysis identified 66 differentially expressed transcripts. Pathways were identified using Ingenuity and DAVID software. Array results from two pooled samples (5 rats in each pool) for n=10 per treatment group were used for comparisons. Comparisons between Western vs. Control, Western + DHA vs. Control and Western + DHA vs. Western diets was subjected to analysis to generate log fold changes.
Project description:LV hypertrophy is associated with Western diet consumption, while intake of n-3 polyunsaturated fatty acids is associated with anti-hypertrophic effects. We treated rats for 12 weeks with either a Control diet, a Western diet or a Western + DHA diet. For each of the 3 dietary treatments there were 2 pooled samples of heart tissue (with each pooled sample representing 5 rats) for a total of 6 arrays. Microarray analysis identified 66 differentially expressed transcripts. Pathways were identified using Ingenuity and DAVID software. Array results from two pooled samples (5 rats in each pool) for n=10 per treatment group were used for comparisons. Comparisons between Western vs. Control, Western + DHA vs. Control and Western + DHA vs. Western diets was subjected to analysis to generate log fold changes. A dietary treatment of 12 weeks was used in an effort to produce LVH while limiting the development of comorbidities. Microarray analysis was performed on pooled samples, followed by qRT-PCR and Western blot analysis. Groups were Control, Western and Western + DHA. Comparisons between groups are expressed as LogFC (i.e. LogFC_WESvCTRL, LogFC_DHAVCTRL, LogFC_DHAvWES), available in Series supplementary files.
Project description:To determine the effect of consumption of a quercetin-rich diet on obesity and dysregulated hepatic gene expression, C56BL/6J mice were fed for 20 weeks on control or a Western diet high in fat, cholesterol and sucrose, both with or without 0.05% quercetin. Chronic dietary intake of quercetin reduced body weight gain and visceral and liver fat accumulation, and improved hyperglyceamia, hyperinsulinaemia, dyslipidaemia in mice fed a Western-style diet. Feeding a Western-style diet altered expression of genes related to inflammatory responses, lipid metabolism and oxidative phosphorylation in C57BL/6J mice after 20 weeks. The results from exhaustive gene expression analysis showed that quercetin minimally influenced hepatic gene expression in mice fed the Western diet. The gene screening results (GSEA) were consistent with the notion that it did improve mitochondrial function to some extent. Quantitative RT-PCR analysis indicated that quercetin did influence important regulators of fat accumulation and metabolic disorders. Our results suggest that quercetin reduces fat accumulation presumably through decreasing oxidative stress and increasing PPARα expression, and the following improvement of gene expression related to steatosis in the liver. C56BL/6J mice were fed for 20 weeks on AIN93G (con) or a Western diet high in fat, cholesterol and sucrose, both with or without 0.05% quercetin for 20 weeks.
Project description:Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in Western countries. There is growing evidence that dysbiosis of the intestinal microbiota and disruption of microbiota-host interactions contribute to the pathology of NAFLD. We previously demonstrated that gut microbiota derived tryptophan metabolite indole-3-acetate (I3A) was decreased in both cecum and liver of high-fat diet-fed mice and attenuated the expression of inflammatory cytokines in macrophages and TNF-a and fatty acid induced inflammatory responses in an aryl-hydrocarbon receptor (AhR) dependent manner in hepatocytes. In this study, we investigated the effect of orally administered I3A in a mouse model of diet induced NAFLD. Western diet (WD)-fed mice given sugar water (SW) with I3A showed dramatically decreased serum ALT, hepatic TG, liver steatosis, hepatocyte ballooning, lobular inflammation, and hepatic production of inflammatory cytokines, compared to WD-fed mice given only SW. Metagenomic analysis show that I3A administration did not significantly modify the intestinal microbiome, suggesting that I3A’s beneficial effects likely reflect the metabolite’s direct actions on the liver. Administration of I3A partially reversed WD induced alterations of liver metabolome and proteome, notably, decreasing expression of several enzymes in hepatic lipogenesis and β- oxidation. Mechanistically, we also show that AMP-activated protein kinase (AMPK) mediates the anti-inflammatory effects of I3A in macrophages. The potency of I3A in alleviating liver steatosis and inflammation clearly demonstrates its potential as a therapeutic modality for preventing the progression of steatosis to NASH.
Project description:SHP (small heterodimer partner; NR0B2) belongs to the nuclear hormone receptor superfamily, which regulates numerous developmental and metabolic cellular functions. To study physiological function of SHP, we generated congenic SHP-/- mice on C57Bl/6 background. When the congenic SHP-/- mice were challenged with a western diet (high fat, hgih sucrose, high cholesterol) for 20 weeks, they were resistant to diet induced obesity but severely glucose intolerant compared to wild type control mice. However, their overall peripheral tissue insulin sensitivity was normal when assessed by insulin tolerance test. Next, we examined the glucose stimulated insulin secretion (GSIS) in isolated islets from these animals. Islets from SHP-/- mice showed strongly impaired GSIS especially fed the western diet, which is believed to be a major factor causing the whole body glucose intolerance in SHP-/- mice. Therefore, we explored gene expression in islets using illumina beadchip array to understand mechanisms underneath the impaired GSIS.
Project description:Non-alcoholic fatty liver disease (NAFLD) is characterized by the accumulation of lipid droplets (LD) in hepatocytes. NAFLD development and progression is associated with an increase in hepatic cholesterol and decreased autophagy and lipophagy flux. Previous studies have shown that the expression of lysosomal acid lipase (gene=LIPA, protein=LAL), which can hydrolyze both triglyceride and cholesteryl esters, is inversely correlated with the severity of NAFLD. In addition, ablation of LAL activity results in profound NAFLD. Based on this, we predicted that overexpressing LIPA in the livers of mice fed a Western diet (FPC) would prevent the development of NAFLD. As expected, mice fed the FPC diet exhibited numerous markers of NAFLD including hepatomegaly, lipid accumulation, and inflammation. Unexpectedly, LAL overexpression did not attenuate steatosis and had only minor effects on neutral lipid composition. However, LAL overexpression exacerbated inflammatory gene expression and infiltration of immune cells in mice fed the FPC diet. LAL overexpression also resulted in abnormal phagosome accumulation and lysosomal lipid accumulation depending upon the dietary treatment. Hepatic overexpression of LAL drove immune cell infiltration and inflammation and did not attenuate the development of NAFLD suggesting that targeting LAL expression is not a viable route to treat NAFLD.