Advanced glycation end products induce the apoptosis of and inflammation in mouse podocytes through CXCL9-mediated JAK2/STAT3 pathway activation

Diabetic nephropathy (DN) is a serious and one of the most common microvascular complications of diabetes. There is accumulating evidence to indicate that advanced glycation end products (AGEs), senescent macroprotein derivatives formed at an accelerated rate under conditions of diabetes, play a role in DN. In this study, we found that the serum and urine levels of C-X-C motif chemokine ligand 9 (CXCL9) were significantly elevated in patients with DN compared with healthy controls. Based on an in vitro model of mouse podocyte injury, AGEs decreased the proliferation of podocytes and increased the expression of CXCL9 and C-X-C motif chemokine receptor 3 (CXCR3), and promoted the activation of signal transducer and activator of transcription 3 (STAT3). The knockdown of CXCL9 by the transfection of mouse podoyctes with specific siRNA significantly increased the proliferation and decreased the apoptosis of the podoyctes. Moreover, the levels of inflammatory factors, such as tumor necrosis factor (TNF)-α and interleukin (IL)-6 were also decreased in the podoyctes transfected with siRNA-CXCL9, accompanied by the increased expression of nephrin and podocin, and decreased levels of Bax/Bcl-2 and activated caspase-3. The knockdown of CXCL9 also led to the inactivation of the Janus kinase 2 (JAK2)/STAT3 pathway. Importantly, the use of the JAK2 inhibitor, AG490, and valsartan (angiotensin II receptor antagonist) attenuated the injury induced to mouse podoyctes by AGEs. On the whole, and to the best of our knowledge, this study demonstrates for the first time that AGEs exert pro-apoptotic and pro-inflammatory effects in mouse podoyctes through the CXCL9-mediated activation of the JAK2/STAT3 pathway. Thus, our data provide a potential therapeutic target for DN.