Curcumin relieved cisplatin-induced kidney inflammation through inhibiting Mincle-maintained M1 macrophage phenotype.

Acute kidney injury (AKI) is a common kidney disease with a high risk of death and can develop into chronic kidney disease (CKD) and renal failure eventually. Curcumin, an herbal supplement, has been reported exhibiting a renoprotective role in AKI. However, the underlying mechanism is largely unclear. Recent research showed that Mincle (Macrophage-inducible C-type lectin) maintained M1 macrophage polarization, which plays a key role in kidney injury of AKI through up-regulating the expression and secretion of inflammatory cytokines. Here, we investigated the effects of Curcumin on Mincle expression and macrophage polarization in vitro using lipopolysaccharide (LPS) induced macrophage inflammatory cell model and in vivo using a cisplatin induced murine AKI (cis-AKI) model. Cell activation, inflammatory cytokines expression and secretion, protein levels, macrophage polarization and renal pathology were analyzed. Our results showed that Curcumin markedly reduced the mRNA expression and secretion of IL-1β, IL-6, TNFα and MCP-1 in LPS stimulated RAW264.7 cell and the supernatant. The same results were found in Curcumin treated cis-AKI kidney and blood. The data also demonstrated that Curcumin remarkably down-regulated mRNA expression and protein level of Mincle in cis-AKI kidney and also reduced expression of iNOS (M1 macrophage marker) as well as inhibited the activation of Syk and NF-kB. Interestingly, although Mincle deletion in RAW264.7 cell largely decreased the LPS-induced protein level of iNOS, Curcumin cannot further reduce expression of iNOS without Mincle, indicating that Curcumin inhibits M1 macrophage with a Mincle-dependent pattern. Furthermore, flow cytometry results showed that Curcumin significantly decreased the iNOS positive macrophages and increased the CD206 (M2 macrophage marker) positive macrophages in vivo and in vitro. Our findings prove that Curcumin protects kidney from cisplatin induced AKI through inhibiting Mincle maintained M1 macrophage phenotype, that may provide a specific renoprotection mechanism for Curcumin to develop it as a new therapeutic candidate for AKI.

Tan RZ ，Liu J ，Zhang YY ，Wang HL ，Li JC ，Liu YH ，Zhong X ，Zhang YW ，Yan Y ，Lan HY ，Wang L ... -  《-》

Astragalus propinquus Schischkin and Panax notoginseng (A&P) compound relieved cisplatin-induced acute kidney injury through inhibiting the mincle maintained macrophage inflammation.

Acute kidney injury (AKI) is a common disease in hospitalized patients, especially in critically ill patients. It is characterised with high morbidity and mortality, and is also an important cause of chronic kidney disease and chronic renal failure. Astragalus propinquus Schischkin and Panax notoginseng (A&P) compound, a famous traditional Chinese medicine, consists of Astragalus propinquus Schischkin, Panax notoginseng, Angelica sinensis, Achyranthes bidentata, and Ecklonia kurome, has been widely used for the treatment of various kidney diseases in the southwest of China. However, the effects of A&P on treatment of AKI and its underlying mechanism are needed to be uncovered. Recent researches reported that Mincle (Macrophage-inducible C-type lectin) plays a key role in renal injury of AKI by regulating the expression and secretion of inflammatory cytokines on macrophage through modulating NF-κB signaling pathway. Here, we aimed to investigate the renoprotective effect of A&P on AKI and whether by inhibiting Mincle. We established a lipopolysaccharide (LPS)-induced Bone Marrow-Derived Macrophage (BMDM) inflammatory cell model and a cisplatin-induced mouse AKI model in vitro and in vivo. Renal histopathology staining was performed to observe kidney morphology. The expression and secretion of inflammatory cytokines were detected by real-time PCR and Enzyme-linked immunosorbent assay. Western blotting was used to detect the protein levels and Flow cytometry performed to detect polarization of macrophage. The results showed that A&P significantly reduced the mRNA expression of IL-1β, IL-6, TNFα and MCP-1 in LPS-stimulated BMDM cells, and secretion of IL-1β and IL-6 in supernatant. The same results were found in Cisplatin-induced AKI kidney and serum after treatment with A&P. The data also showed that A&P strongly reduced the mRNA and protein levels of Mincle in vitro and vivo, and also inhibited the activation of Syk and NF-κB. Notably, A&P down-regulated the M1 macrophage marker iNOS, which may relate to the inhibition of Mincle. Interestingly, both overexpression of Mincle by transfection of pcDNA3.1-Mincle plasmid and administration of TDB (a ligand of Mincle) can significantly abolished the A&P-inhibited inflammation in BMDM, suggesting Mincle pathway play a key role in macrophage inflammation in AKI. Our findings indicated that A&P protected kidney from inhibiting inflammation through down-regulating of Mincle pathway in macrophage in AKI. It provides a potential medicine compound for the treatment of AKI.

Hui D ，Rui-Zhi T ，Jian-Chun L ，Xia Z ，Dan W ，Jun-Ming F ，Li W ... -  《-》

The pattern recognition receptor, Mincle, is essential for maintaining the M1 macrophage phenotype in acute renal inflammation.

Mincle (macrophage-inducible C-type lectin, Clec4e) is a transmembrane pattern recognition receptor involving the innate immunity, but its role in kidney disease is still unexplored. In the obstructed kidney of the unilateral ureteral obstruction model of renal injury, Mincle was specifically detected in the infiltrating M1 macrophages (CD68+iNOS+ cells) on day one but was rapidly reduced following reduction of M1 macrophages during the progression of kidney injury. Interestingly, Mincle-expressing macrophages were progressively increased in the cisplatin-induced acute kidney injury model, where iNOS expression was detected in the CD68+ cells following Mincle induction. Adaptive transfer of Mincle+ M1 macrophages largely promoted cisplatin-induced renal inflammation, which was prevented by the knockdown of Mincle in the transferred cells. Mincle was tightly regulated by TLR4/NF-κB signaling as evidenced by the binding of NF-κB/p65 to the promoter region of Mincle in LPS-primed macrophages. Blocking TLR4 or NF-κB suppressed LPS-induced Mincle expression on macrophages. Importantly, Mincle was found to be essential for maintaining the inflammatory phenotypes of M1 macrophages through the Syk signaling pathway since knockdown of Mincle or inhibition of Syk suppressed LPS-induced IL-1β, MCP-1, and iNOS expression. Thus, Mincle is induced specifically on M1 macrophages, where Mincle-Syk signaling promotes and maintains inflammatory phenotypes of M1 macrophages in acute renal inflammation. Hence, targeting Mincle may be a novel therapy for acute kidney injury associated with M1 macrophages.

Lv LL ，Tang PM ，Li CJ ，You YK ，Li J ，Huang XR ，Ni J ，Feng M ，Liu BC ，Lan HY ... -  《-》

Quercetin protects against cisplatin-induced acute kidney injury by inhibiting Mincle/Syk/NF-κB signaling maintained macrophage inflammation.

Acute kidney injury (AKI) with high incidence and mortality is the main cause of chronic kidney disease. Previous studies have indicated that quercetin, an abundant flavonoid in plants, exhibited renoprotective role in AKI. However, the underlying mechanism is largely unknown. In this study, we try to explore whether quercetin protects against AKI by inhibiting macrophage inflammation via regulation of Mincle/Syk/NF-κB signaling. The results demonstrated that quercetin can significantly inhibit expression and secretion of IL-1β, IL-6, and TNF-α in LPS-induced bone marrow-derived macrophages (BMDMs) and reduce activity of Mincle/Syk/NF-κB signaling in vitro. We also found that quercetin can strongly reduce the concentration of serum creatinine, BUN, IL-1β, IL-6, and TNF-α in cisplatin-induced AKI model. Furthermore, quercetin down-regulated protein levels of Mincle, phosphorylated Syk and NF-κB in kidney macrophages of AKI, as well as inhibited M1, up-regulated M2 macrophage activity. Notably, the down-regulation of LPS-induced inflammation by quercetin was reversed after adding TDB (an agonist of Mincle) in BMDMs, suggesting that quercetin suppresses macrophage inflammation may mainly through inhibiting Mincle and its downstream signaling. In summary, these findings clarified a new mechanism of quercetin improving AKI-induced kidney inflammation and injury, which provides a new drug option for the clinical treatment of AKI.

Tan RZ ，Wang C ，Deng C ，Zhong X ，Yan Y ，Luo Y ，Lan HY ，He T ，Wang L ... -  《-》

Isorhamnetin ameliorates cisplatin-induced acute kidney injury in mice by activating SLPI-mediated anti-inflammatory effect in macrophage.

Jian J ，Yu-Qing L ，Rang-Yue H ，Xia Z ，Ke-Huan X ，Ying Y ，Li W ，Rui-Zhi T ... -  《-》