Curcumin treatment was reported to delay the progression of OA, but its underlying mechanism remains unclear. In this study, we aimed to investigate the molecular mechanism underlying the role of curcumin in OA treatment. Accordingly, by conducting MTT and flow cytometry assays, we found that the exosomes derived from curcumin‐treated MSCs helped to maintain the viability while inhibiting the apoptosis of model OA cells. Additionally, quantitative real‐time PCR and Western blot assays showed that the exosomes derived from curcumin‐treated MSCs significantly restored the down‐regulated miR‐143 and miR‐124 expression as well as up‐regulated NF‐kB and ROCK1 expression in OA cells. Mechanistically, curcumin treatment decreased the DNA methylation of miR‐143 and miR‐124 promoters. In addition, the 3’ UTRs of NF‐kB and ROCK1 were proven to contain the binding sites for miR‐143 and miR‐124, respectively. Therefore, the up‐regulation of miR‐143 and miR‐124 in cellular and mouse OA models treated with exosomes remarkably restored the normal expression of NF‐kB and ROCK1. Consequently, the progression of OA was attenuated by the exosomes. Our results clarified the molecular mechanism underlying the therapeutic role of MSC‐derived exosomes in OA treatment.

Kidney fibrosis and renal tubular epithelial-to-mesenchymal transition (EMT) are the main pathological changes of diabetic nephropathy (DN), which eventually leads to end-stage renal disease. Previous studies have suggested that echinacoside (ECH) is antifibrotic in the liver. However, the effect of ECH on kidney fibrosis in DN and its mechanisms are unknown. This study was performed to explore the effect of ECH on kidney fibrosis and also the molecular mechanisms of ECH in a db/db mice model of DN. Our results showed that, relative to db/db mice, the mice in the ECH group had an improved general state and reduced blood glucose and 24-hour urinary protein levels. The deterioration of renal function was delayed due to treatment with ECH. We also observed that ECH can improve histopathological findings in the kidneys of db/db mice, including collagen deposition, mesangial cell and mesangial matrix hyperplasia, basement membrane thickening, and podocyte reduction. Moreover, ECH inhibited the TGF-β1/Smads signaling pathway, downregulated fibronectin (FN), collagen IV, and alpha-smooth muscle actin (α-SMA) levels, and upregulated E-cadherin level in the db/db mice model of DN. Our findings indicate that ECH has a therapeutic effect on DN, including the inhibition of renal tubular EMT and kidney fibrosis. Furthermore, ECH inhibits kidney fibrosis through regulation of the TGF-β1/Smads signaling pathway.

Objective. The antidiabetes drug astragalus polysaccharide (APS) is capable of increasing insulin sensitivity in skeletal muscle and improving whole-body glucose homeostasis. Recent studies suggest that skeletal muscle secreted growth factor myostatin plays an important role in regulating insulin signaling and insulin resistance. We hypothesized that regulation of skeletal muscle myostatin expression may be involved in the improvement of insulin sensitivity by APS. Methods. APS was administered to 13-week-old diabetic KKAy and nondiabetic C57BL/6J mice for 8 weeks. Complementary studies examined APS effects on the saturated acid palmitate-induced insulin resistance and myostatin expression in C2C12 cells. Results. APS treatment ameliorated hyperglycemia, hyperlipidemia, and insulin resistance and decreased the elevation of myostatin expression and malondialdehyde production in skeletal muscle of noninsulin-dependent diabetic KKAy mice. In C2C12 cells in vitro, saturated acid palmitate-induced impaired glucose uptake, overproduction of ROS, activation of extracellular regulated protein kinases (ERK), and NF-κB were partially restored by APS treatment. The protective effects of APS were mimicked by ERK and NF-κB inhibitors, respectively. Conclusion. Our study demonstrates elevated myostatin expression in skeletal muscle of type 2 diabetic KKAy mice and in cultured C2C12 cells exposed to palmitate. APS is capable of improving insulin sensitivity and decreasing myostatin expression in skeletal muscle through downregulating ROS-ERK-NF-κB pathway.

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