Aloperine is a quinolizidine alkaloid extracted from the leaves of Sophora plants. It has been recognized with the potential to treat inflammatory and allergic diseases as well as tumors. In this report, we demonstrate that pretreatment with aloperine provided protection for mice against ischemia-reperfusion (IR)-induced acute renal injury as manifested by the attenuated inflammatory infiltration, reduced tubular apoptosis, and well-preserved renal function. Mechanistic studies revealed that aloperine selectively repressed IL-1β and IFN-γ expression by regulating PI3K/Akt/mTOR signaling and NF-κB transcriptional activity. However, aloperine did not show a perceptible impact on IL-6 and TGF-β expression and the related Jak2/Stat3 signaling. It was also noted that aloperine regulates AP-1 activity, through which it not only enhances SOD expression to increase reactive oxygen species (ROS) detoxification but also promotes the expression of antiapoptotic Bcl-2, thereby preventing tubular cells from IR-induced apoptosis. Collectively, our data suggest that administration of aloperine prior to IR insults, such as renal transplantation, could be a viable approach to prevent IR-induced injuries.

Kdm2a catalyzes H3K36me2 demethylation to play an intriguing epigenetic regulatory role in cell proliferation, differentiation, and apoptosis. Herein we found that myeloid-specific knockout of Kdm2a (LysM-Cre-Kdm2af/f, Kdm2a−/−) promoted macrophage M2 program by reprograming metabolic homeostasis through enhancing fatty acid uptake and lipolysis. Kdm2a−/− increased H3K36me2 levels at the Pparg locus along with augmented chromatin accessibility and Stat6 recruitment, which rendered macrophages with preferential M2 polarization. Therefore, the Kdm2a−/− mice were highly protected from high-fat diet (HFD)-induced obesity, insulin resistance, and hepatic steatosis, and featured by the reduced accumulation of adipose tissue macrophages and repressed chronic inflammation following HFD challenge. Particularly, Kdm2a−/− macrophages provided a microenvironment in favor of thermogenesis. Upon HFD or cold challenge, the Kdm2a−/− mice manifested higher capacity for inducing adipose browning and beiging to promote energy expenditure. Collectively, our findings demonstrate the importance of Kdm2a-mediated H3K36 demethylation in orchestrating macrophage polarization, providing novel insight that targeting Kdm2a in macrophages could be a viable therapeutic approach against obesity and insulin resistance.

Lymphangiogenesis occurs during renal fibrosis in patients with chronic kidney diseases and vascular endothelial growth factor (VEGF)-C is required for the formation of lymphatic vessels; however, the underlying mechanisms remain unclear. We demonstrate that macrophages can regulate unilateral ureteral obstruction (UUO)-induced renal lymphangiogenesis by expressing high levels of VEGF-C by C-C motif chemokine receptor 2 (CCR2)-mediated signaling. Mice deficient in Ccr2 manifested repressed lymphangiogenesis along with attenuated renal injury and fibrosis after UUO induction. The infiltrated macrophages after UUO induction generated a microenvironment in favor of lymphangiogenesis, which likely depended on Ccr2 expression. Mechanistic studies revealed that CCR2 is required for macrophages to activate phosphatidylinositol 3-kinase (PI3K)-AKT-mechanistic target of rapamycin (mTOR) signaling in response to its ligand monocyte chemoattractant protein 1 stimulation, whereas hypoxia-inducible factor (HIF)-1α is downstream of PI3K-AKT-mTOR signaling. HIF-1α directly bound to the VEGF-C promoter to drive its expression to enhance lymphangiogenesis. Collectively, we characterized a novel regulatory network in macrophages, in which CCR2 activates PI3K-AKT-mTOR signaling to mediate HIF-1α expression, which then drives VEGF-C expression to promote lymphangiogenesis.