Overexpression of toll-like receptor 2 in glomerular endothelial cells and podocytes in septic acute kidney injury mouse model

Acute kidney injury (AKI) is one of the most common complications in patients with severe sepsis. The development of septic AKI increases patients' mobility and even mortality. Toll-like receptor 2 (TLR2), as a membrane surface receptor for bacterial, fungal, viral and certain endogenous substances, has been described to contribute to the development of septic AKI; however, the renal cell types associating TLR2 overactivation in septic AKI has not been described. In the current study, we investigated the TLR2 activation patterns in the kidney of lipopolysaccharide-induced septic AKI mice. Our results demonstrated that mRNA level of TLR2 significantly increased in the kidney of lipopolysaccharide-treated mice. Immunohistochemistry revealed the overactivation of TLR2 in the glomeruli. Double immunofluorescence analysis shows the precise distribution of TLR2 by showing the colocalization of TLR2 in glomeruli with synaptopodin, a podocyte marker, and Tie2, an endothelial marker. In addition, proapoptotic molecules Bax and Caspase-3 were increased in the glomeruli of lipopolysaccharide-treated mice. Together, the current study indicates that TLR2 is overactivated in the glomerular endothelial cells and podocytes in septic AKI mice, while the abundance of Bax and Caspase-3 were increased in the glomeruli of these mice, it may supply a clue that TLR2 induced these cell apoptosis in AKI. This finding provides an alternative mechanism to understand AKI development and potential targets for treatment.