Activation of M1 macrophages promotes diabetic kidney disease by modulating glycolysis via HIF-1α-HK2 signaling pathway.

OBJECTIVE: Macrophages and glycolysis play a pivotal role in diabetic kidney disease (DKD). However, the regulation of macrophage glycolysis and its mechanism are still unclear in DKD. Thus, this research intends to investigate the regulatory mechanism of macrophage glycolysis during DKD. METHODS: Macrophage polarization in patients with DKD and in mice was assessed using RT-qPCR and immunofluorescence. DKD was induced in the mice through injection of streptozotocin, and a high-fat diet was administered. Hematoxylin and eosin staining and Masson's trichrome staining were employed to identify pathological alterations and visualize renal collagen fibers in the model mice. Glycolytic metabolite levels were quantified using a commercially available kit. Protein levels of HK2, PFK1, LDH, PK1, and GLUT1 were analyzed via western blotting. Hkb-20 cells exposed to high glucose were utilized as an in vitro experimental model. THP-1 cells were co-cultivated with Hkb-20 cells. The impact of macrophage polarization on the functionality of Hkb-20 cells was assessed through CCK8 assay, flow cytometry, and wound healing assay. Levels of IL-6, IL-1β, and TNF-α were evaluated using ELISA kits. Immunofluorescence staining was employed to examine the co-localization of hypoxia-inducible factor-1 (HIF-1α) and HK2. RESULTS: We found that M1 macrophage polarization and enhanced glycolysis activity emerged in DKD patients and mice. Furthermore, we demonstrated that M1 macrophage polarization promotes glycolysis activity in macrophage and model mice. Moreover, we found that HIF-1α and HK2 were obviously enhanced in the serum of DKD cases and mice. Mechanically, we revealed that HIF-1α participates in M1 macrophage polarization and glycolysis activity in vitro by activating HK2 transcription. CONCLUSION: We demonstrated that M1 macrophage polarization mediated glycolysis contributed to DKD via regulating HIF-1α-HK2 signaling pathway.