Current evidence suggests that gut dysbiosis drives obesity and non-alcoholic fatty liver disease (NAFLD) pathogenesis. Toll-like receptor 2 (TLR2) and TLR6 specifically recognize components of Gram-positive bacteria. Despite the potential implications of TLR2 in NAFLD pathogenesis, the role of TLR6 has not been addressed. Our aim is to study a potential role of TLR6 in obesity-related NAFLD. Forty morbidly obese patients undergoing bariatric surgery were prospectively studied. Cell surface expression of TLR2 and TLR6 was assessed on peripheral blood mononuclear cells (PBMCs) by flow cytometry. Freshly isolated monocytes were cultured with specific TLR2/TLR6 agonists and intracellular production of cytokines was determined by flow-cytometry. In liver biopsies, the expression of TLR2 and TLR6 was analyzed by immunohistochemistry and cytokine gene expression using RT-qPCR. TLR6 expression in PBMCs from non-alcoholic steatohepatitis (NASH) patients was significantly higher when compared to those from simple steatosis. The production of pro-inflammatory cytokines in response to TLR2/TLR6 stimulation was also significantly higher in patients with lobular inflammation. Hepatocyte expression of TLR6 but not that of TLR2 was increased in NAFLD patients compared to normal liver histology. Deregulated expression and activity of peripheral TLR6 in morbidly obese patients can mirror the liver inflammatory events that are well known drivers of obesity-related NASH pathogenesis. Moreover, TLR6 is also significantly overexpressed in the hepatocytes of NAFLD patients compared to their normal counterparts. Thus, deregulated TLR6 expression may potentiate TLR2-mediated liver inflammation in NAFLD pathogenesis, and also serve as a potential peripheral biomarker of obesity-related NASH. Full article

B-cells have been long accepted as the main cellular component in humoral responses. Their effector function is based on antibody and cytokine production. The development of donor-specific antibodies by B-cells has deleterious consequences in graft and patients survival. Recently, a new subset of IL-10-secreting B-cells with regulatory capacity in allergic and autoimmune diseases has been shown. Such regulatory function changes the apprehension of B-cells as effector cells and increases the complexity to the immuno-regulatory networks. New therapies targeting B-cells should consider that depleting B-cells potentially impairs regulatory B-cells (Bregs) and that modulating or favoring the maintenance and function of Bregs would be important for the achievement of humoral tolerance. Unfortunately, few direct pieces of evidence of Breg involvement in allograft tolerance models has been described. Here, we summarize the current knowledge of the role of Bregs in transplantation. Full article