Paeoniflorin suppresses kidney inflammation by regulating macrophage polarization via KLF4-mediated mitophagy.

BACKGROUND: Macrophages M1 polarization involved in the process of renal inflammatory injury, is a well-established hallmark of chronic kidney disease (CKD). Paeoniflorin (PF), a water-soluble monoterpene glycoside extracted from Paeonia lactiflora, revealed renal anti-inflammatory activities in our previous study. However, the potential molecular mechanism of PF on CKD remains unknown. PURPOSE: The present study aims to investigate the regulation of PF on macrophage polarization in CKD. METHODS: A CKD model was established by cationic bovine serum albumin and a murine macrophage cell line RAW264.7 induced with lipopolysaccharide (LPS) were used to clarify the underlying mechanisms of PF in CKD. RESULTS: Results showed that PF exhibited favorable protective effects on CKD model mice by promoting renal function, ameliorating renal pathological injury and podocyte damage. Furthermore, PF inhibited the infiltration of M1 macrophage marker CD68 and iNOS in kidney tissue, but increased the proportion of M2 macrophage marker CD206. In RAW264.7 cells stimulated with LPS, the levels of cytokines including IL-6, IL-1ß, TNF-α, MCP-1 were lessened under PF treatment, while the levels of Arg1, Fizz1, IL-10 and Ym-1 were augmented. These results indicated that PF promoted macrophage polarization from M1 to M2 in vivo and in vitro. More importantly, PF repaired the damaged mitochondria through increasing mitochondrial membrane potential and reducing ROS accumulation. The mitophagy-related proteins PINK1, Parkin, Bnip3, P62 and LC3 were up-regulated by PF, accompanied by the incremental expressions of Krüppel-like transcription factor 4 (KLF4). Moreover, the promotion of mitophagy and inhibition of M1 macrophage polarization owing to PF were reversed by mitophagy inhibitor Mdivi-1 or silencing KLF4. CONCLUSION: Overall, PF suppressed renal inflammation by promoting macrophage polarization from M1 to M2 and inducing mitophagy via regulating KLF4. It is expected to provide a new strategy for exploring the effects of PF in treating CKD.

Danshen injection induces autophagy in podocytes to alleviate nephrotic syndrome via the PI3K/AKT/mTOR pathway.

BACKGROUND: Danshen injection (DSI) is an agent extracted from the Salvia miltiorrhiza Bunge, a natural drug commonly used to alleviate kidney diseases. However, the material basis and therapeutic effects of DSI on nephrotic syndrome (NS) remain unclear. PURPOSE: To investigate the material basis of DSI and the therapeutic effects and underlying mechanisms of NS. METHODS: NS models were established using adriamycin-induced BALB/c mice and lipopolysaccharide-induced mouse podocytes (MPC-5). Following DSI and prednisone administration, kidney coefficients, 24 h urine protein, blood urea nitrogen, and serum creatinine levels were tested. Histomorphology was observed by periodic acid-Schiff staining and hematoxylin and eosin staining of the kidney sections. The glomerular basement membrane and autophagosomes of the kidneys were observed using transmission electron microscopy. Nephrin and desmin levels in the glomeruli were tested using immunohistochemistry. The viability of MPC-5 cells was tested using cell counting kit-8 after chloroquine and rapamycin administration in combination with DSI. The in vivo and in vitro protein levels of phosphatidylinositol 3-kinase (PI3K), AKT, phosphorylated AKT (Ser473), mammalian target of rapamycin (mTOR), microtubule-associated protein light chain 3 (LC3), beclin1, cleaved caspase-3, and caspase-3 were detected using western blotting. RESULTS: Our results showed that DSI contained nine main components: caffeic acid, danshensu, lithospermic acid, rosmarinic acid, salvianolic acid A, salvianolic acid B, salvianolic acid C, salvianolic acid D, and 3, 4-Dihydroxybenzaldehyde. In in vivo studies, the NS mice showed renal function and pathological impairment. Podocytes were damaged, with decreased levels of autophagy and apoptosis, accompanied by inhibition of the PI3K/AKT/mTOR signaling. DSI administration resulted in improved renal function and pathology in NS mice, with the activation of autophagy and PI3K/AKT/mTOR signaling in the kidneys. Additionally, podocytes were less damaged and intracellular autophagosomes were markedly increased. In vitro studies have shown that DSI activated MPC-5 autophagy and reduced apoptosis via the PI3K/AKT/mTOR pathway. CONCLUSION: Collectively, this study demonstrated that DSI activated podocyte autophagy and reduced apoptosis via the PI3K/AKT/mTOR signaling, ultimately attenuating NS. Our study clarified the main components of DSI and elucidated its therapeutic effects and potential mechanisms for NS, providing new targets and agents for the clinical treatment of NS.