Highlights d The overall gut microbiota shifts in parallel with glycemic status in humans d The shifts are observed in the absence of diabetes treatment d The variations strongly associate with insulin resistance, but not fasting glucose d Butyrate-producing bacteria are reduced in prediabetes and type 2 diabetes

Clear-cell renal cell carcinoma (RCC) is, in most cases, caused by loss of function of the tumor suppressor gene von Hippel–Lindau, resulting in constitutive activation of hypoxia-inducible factor (HIF)-1α and expression of hypoxia-induced genes in normoxic conditions. Clear-cell RCC cells are characterized histologically by accumulation of cholesterol, mainly in its ester form. The origin of the increased cholesterol remains unclear, but it is likely explained by an HIF-1α-driven imbalance between cholesterol uptake and excretion. Here, we showed that expression of the very low-density lipoprotein receptor (VLDL-R) was significantly increased in clear-cell RCC human biopsies compared with normal kidney tissue. Partial knockdown of HIF-1α in clear-cell RCC cells significantly reduced the VLDL-R expression, and knockdown of either HIF-1α or VLDL-R reduced the increased lipid accumulation observed in these cells. We also showed increased uptake of fluorescently labeled lipoproteins in clear-cell RCC cells, which was significantly reduced by knockdown of HIF-1α or VLDL-R. Taken together, our results support the concept that the pathological increase of HIF-1α in clear-cell RCC cells upregulates VLDL-R, which mediates increased uptake and accumulation of lipids. These results explain the morphological characteristics of clear-cell RCC, and open up novel possibilities for detection and treatment of clear-cell RCC.

Inflammation in the vascular wall is important for development of atherosclerosis. We have shown previously that arachidonate 15-lipoxygenase type B (ALOX15B) is more highly expressed in human atherosclerotic lesions than in healthy arteries. This enzyme oxidizes fatty acids to substances that promote local inflammation and is expressed in lipid-loaded macrophages (foam cells) present in the atherosclerotic lesions. Here, we investigated the role of ALOX15B in foam cell formation in human primary macrophages and found that silencing of human ALOX15B decreased cellular lipid accumulation as well as proinflammatory cytokine secretion from macrophages. To investigate the role of ALOX15B in promoting the development of atherosclerosis in vivo, we used lentiviral shRNA silencing and bone marrow transplantation to knockdown mouse Alox15b gene expression in LDL-receptor-deficient (Ldlr −/−) mice. Knockdown of mouse Alox15b in vivo decreased plaque lipid content and markers of inflammation. In summary, we have shown that ALOX15B influences progression of atherosclerosis, indicating that this enzyme has an active proatherogenic role.

Introduction Prevalence of obesity and associated diseases, including type 2 diabetes mellitus, dyslipidaemia and non‐alcoholic fatty liver disease (NAFLD), are increasing. Underlying mechanisms, especially in humans, are unclear. Bariatric surgery provides the unique opportunity to obtain biopsies and portal vein blood‐samples. Methods The BARIA Study aims to assess how microbiota and their metabolites affect transcription in key tissues and clinical outcome in obese subjects and how baseline anthropometric and metabolic characteristics determine weight loss and glucose homeostasis after bariatric surgery. We phenotype patients undergoing bariatric surgery (predominantly laparoscopic Roux‐en‐Y gastric bypass), before weight loss, with biometrics, dietary and psychological questionnaires, mixed meal test (MMT) and collect fecal‐samples and intra‐operative biopsies from liver, adipose tissues and jejunum. We aim to include 1500 patients. A subset (approximately 25%) will undergo intra‐operative portal vein blood‐sampling. Fecal‐samples are analyzed with shotgun metagenomics and targeted metabolomics, fasted and postprandial plasma‐samples are subjected to metabolomics, and RNA is extracted from the tissues for RNAseq‐analyses. Data will be integrated using state‐of‐the‐art neuronal networks and metabolic modeling. Patient follow‐up will be ten years. Results Preoperative MMT of 170 patients were analysed and clear differences were observed in glucose homeostasis between individuals. Repeated MMT in 10 patients showed satisfactory intra‐individual reproducibility, with differences in plasma glucose, insulin and triglycerides within 20% of the mean difference. Conclusion The BARIA study can add more understanding in how gut‐microbiota affect metabolism, especially with regard to obesity, glucose metabolism and NAFLD. Identification of key factors may provide diagnostic and therapeutic leads to control the obesity‐associated disease epidemic.

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