Paris Descartes University

About: Paris Descartes University is a government organization based out in Paris, France. It is known for research contribution in the topics: Population & Transplantation. The organization has 20987 authors who have published 37456 publications receiving 1206222 citations. The organization is also known as: Université Paris V-Descartes & Université de Paris V.

Impairment of immunity to Candida and Mycobacterium in humans with bi-allelic RORC mutations

Abstract: Human inborn errors of immunity mediated by the cytokines interleukin-17A and interleukin-17F (IL-17A/F) underlie mucocutaneous candidiasis, whereas inborn errors of interferon-γ (IFN-γ) immunity underlie mycobacterial disease. We report the discovery of bi-allelic RORC loss-of-function mutations in seven individuals from three kindreds of different ethnic origins with both candidiasis and mycobacteriosis. The lack of functional RORγ and RORγT isoforms resulted in the absence of IL-17A/F-producing T cells in these individuals, probably accounting for their chronic candidiasis. Unexpectedly, leukocytes from RORγ- and RORγT-deficient individuals also displayed an impaired IFN-γ response to Mycobacterium. This principally reflected profoundly defective IFN-γ production by circulating γδ T cells and CD4(+)CCR6(+)CXCR3(+) αβ T cells. In humans, both mucocutaneous immunity to Candida and systemic immunity to Mycobacterium require RORγ, RORγT, or both.

Understanding the glucoregulatory mechanisms of metformin in type 2 diabetes mellitus

Abstract: Despite its position as the first-line drug for treatment of type 2 diabetes mellitus, the mechanisms underlying the plasma glucose level-lowering effects of metformin (1,1-dimethylbiguanide) still remain incompletely understood. Metformin is thought to exert its primary antidiabetic action through the suppression of hepatic glucose production. In addition, the discovery that metformin inhibits the mitochondrial respiratory chain complex 1 has placed energy metabolism and activation of AMP-activated protein kinase (AMPK) at the centre of its proposed mechanism of action. However, the role of AMPK has been challenged and might only account for indirect changes in hepatic insulin sensitivity. Various mechanisms involving alterations in cellular energy charge, AMP-mediated inhibition of adenylate cyclase or fructose-1,6-bisphosphatase 1 and modulation of the cellular redox state through direct inhibition of mitochondrial glycerol-3-phosphate dehydrogenase have been proposed for the acute inhibition of gluconeogenesis by metformin. Emerging evidence suggests that metformin could improve obesity-induced meta-inflammation via direct and indirect effects on tissue-resident immune cells in metabolic organs (that is, adipose tissue, the gastrointestinal tract and the liver). Furthermore, the gastrointestinal tract also has a major role in metformin action through modulation of glucose-lowering hormone glucagon-like peptide 1 and the intestinal bile acid pool and alterations in gut microbiota composition.

Signaling Kinase AMPK Activates Stress-Promoted Transcription via Histone H2B Phosphorylation

Abstract: The mammalian adenosine monophosphate–activated protein kinase (AMPK) is a serine-threonine kinase protein complex that is a central regulator of cellular energy homeostasis. However, the mechanisms by which AMPK mediates cellular responses to metabolic stress remain unclear. We found that AMPK activates transcription through direct association with chromatin and phosphorylation of histone H2B at serine 36. AMPK recruitment and H2B Ser36 phosphorylation colocalized within genes activated by AMPK-dependent pathways, both in promoters and in transcribed regions. Ectopic expression of H2B in which Ser36 was substituted by alanine reduced transcription and RNA polymerase II association to AMPK-dependent genes, and lowered cell survival in response to stress. Our results place AMPK-dependent H2B Ser36 phosphorylation in a direct transcriptional and chromatin regulatory pathway leading to cellular adaptation to stress.

Human adipose tissue macrophages: m1 and m2 cell surface markers in subcutaneous and omental depots and after weight loss.

Abstract: Context: Macrophages accumulate in adipose tissue and possibly participate in metabolic complications in obesity. Macrophage number varies with adipose tissue site and weight loss, but whether this is accompanied by phenotypic changes is unknown. Objective: The objective of the study was to characterize the activation state of adipose tissue macrophages in human obesity. Design/Setting: We performed a single-center prospective study. Participants/Interventions: Paired biopsies of sc and omental adipose tissue were obtained during gastric surgery in 16 premenopausal obese women (aged 41.1 ± 8.6 yr; body mass index 43.8 ± 3.4 kg/m2). Subcutaneous adipose tissue biopsies were obtained 3 months later in obese subjects and in 10 nonobese women (aged 43.3 ± 3.5 yr; body mass index 22.5 ± 0.75 kg/m2). The number of macrophages stained with CD40, CD206, and CD163 surface markers was determined by immunochemistry. Main Outcomes: The number of CD40+ macrophages significantly increased with obesity and in omental vs...