Dendrobium officinale Kimura & Migo polysaccharide inhibits hyperglycaemia-induced kidney fibrosis via the miRNA-34a-5p/SIRT1 signalling pathway

Fibrosis is a fundamental change occurring in impaired renal function and plays an important role in the progression of diabetic kidney disease (DKD). Dendrobium officinale Kimura & Migo polysaccharide (DOP), a primary active component of Dendrobium officinale Kimura & Migo, is reported to act on reducing blood glucose, suppressing inflammation. However, the anti-fibrosis effect of DOP in the treatment of DKD is still unclear. To explore the therapeutic effect of DOP on renal fibrosis in DKD. We used db/db mice as a DKD model and administered DOP by oral gavage. The expression of miRNA-34a-5p, SIRT1, and fibrosis molecules (TGF-β, CTGF, and a-SMA) were detected in renal tissue. Human renal tubular epithelium cells (HK-2) were cultured with 5.5 mM glucose (LG) or 25 mM glucose (HG), and intervened with 100–400 μg/ml DOP. The changes of the above indicators were observed in vitro. MiRNA-34a-5p was mainly localised in the nucleus and increased expression in the DKD mice. Inhibition or excitation of miRNA-34a-5p is involved in renal fibrosis by regulating SIRT1. DOP could depress the miRNA-34a-5p/SIRT1 signalling pathway to relieve renal fibrosis. Moreover, DOP has outstanding results in the treatment of DKD through hypoglycaemic action and weight reduction. DOP plays a protective role in arresting or slowing the progression of fibrosis, which may provide a novel clinical treatment strategy for DKD.