| Summary: | Objective To explore the role of pyruvate kinase M20 (PKM2)-regulated glycolysis on nod-like receptor protein 3 (NLRP3)- and absentin melanoma 2 (AIM2)-mediated inflammatory activation of macrophages in diabetic nephropathy (DN). Methods Renal biopsy samples from 30 DN patients and tumor-adjacent renal tissue samples from 20 renal cancer patients were collected for detection of the expressions of the glycolytic marker PKM2, the macrophage infiltration marker CD68 and tumor necrosis factor-α (TNF-α) using immunohistochemistry. The levels of TNF-α, interleukin-1β (IL-1β) and monocyte chemoattractant protein-1 (MCP-1) in serum samples from the DN patients and 20 healthy volunteers were detected by ELISA. In cultured mouse bone marrow-derived macrophages, the effects of mannitol, high-glucose exposure, high-glucose exposure plus PKM2 siRNA, and high-glucose exposure plus glycolysis inhibitor on the expression of PKM2, p-EIF2AK2, EIF2AK2, NLRP3 and AIM2 were detected using Western blotting; the secretion and mRNA expression of TNF-α, IL-1β and MCP-1 were detected by ELISA and RT-PCR, and the lactate content and glucose absorption of the cells were assayed using commercial detection kits. Results Compared with the tumor-adjacent renal tissues, the renal tissues from DN patients showed significantly increased expression of PKM2, CD68 and TNF-α (P < 0.01). In the cell cultures of macrophages, high glucose exposure obviously upregulated the cellular expression of PKM2, p-EIF2AK2, NLRP3 and AIM2 proteins (P < 0.01) and the mRNA expression of TNF-α, IL-1β and MCP-1 (P < 0.01) and increased the levels of TNF-α, IL-1β, MCP-1, lactic acid and glucose in the cell supernatant (P < 0.01). Transfection of the cells with PKM2 siRNA significantly inhibited inflammatory responses of the macrophages induced by high-glucose exposure. Conclusion High glucose stimulation can enhance the level of glycolysis in macrophages and promote the activation of inflammasomes and release of inflammatory cytokines through a mechanism involving the activation of PKM2-EIF2AK2 signaling pathway.
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