Cordyceps is a valuable Chinese medicine, not insect or grass, is a fungus, with ginseng, antler and known as the ‘three treasures of traditional Chinese medicine’, has a deficiency filler essence, protect the lungs and benefit the kidneys, stop bleeding and phlegm and other effects. Modern pharmacology found that it has the function of regulating immunity, anti-tumour, anti-oxidation, anti-fibrosis, anti-apoptosis and so on.
Diabetic nephropathy is one of the common chronic microvascular complications of diabetes mellitus, mainly due to glomerulosclerosis and glomerular filtration dysfunction resulting in increased levels of urinary protein and increased urinary micro-protein exclusion rate of a metabolic disease, which can lead to chronic renal failure. Its pathogenesis is complex, and there is no effective treatment method yet. In recent years, about the protective effect of Cordyceps sinensis in kidney disease has been gradually recognised. It mainly has the following effects:
1、Improve lipid metabolism disorder
Diabetic nephropathy patients have obvious lipid metabolism abnormalities. Hyperlipidaemia can lead to the formation of lipid plugs in the lumen of glomerular capillaries, which can damage the glomerular filtration membrane and lead to proteinuria; moreover, the deposition of lipids in the kidneys can cause the thickening of glomerular basement membrane and the aggregation of extracellular matrix, which can lead to glomerulosclerosis and tubular damage, and ultimately lead to impaired renal function. Recent studies have found that Cordyceps can activate adenylate-activated protein kinase (AMPK) signalling pathway, reduce fatty acid and cholesterol synthesis, and at the same time regulate the expression of genes related to lipid metabolism, promote fatty acid oxidation, and promote lipid metabolism disorders to return to normal.
2、Promote extracellular matrix (ECM) degradation
Imbalance of ECM synthesis and degradation is the key to the destruction of glomerular tissue structure and even glomerulosclerosis. It has been found that Cordyceps sinensis can regulate the expression of matrix metalloproteinase-2/metalloproteinase tissue inhibitor-2 in renal tissues, increase the degradation of type IV collagen, reduce the accumulation of ECM in kidneys, and delay the development of diabetic nephropathy, and the earlier the treatment, the better the therapeutic effect.
3、Inhibit oxidative stress
Oxidative stress is involved in the main pathway of the development of diabetic microvascular and macrovascular complications, and oxidative and antioxidant balance is necessary to maintain the stability of the internal environment. Excessive reactive oxygen clusters generated in diabetic nephropathy are difficult to be removed by the body, leading to the accumulation of reactive oxygen clusters in the body, which ultimately causes cell death and accelerates the progression of diabetic nephropathy to end-stage renal disease. Studies have shown that Cordyceps sinensis can improve the renal function of rats with diabetic nephropathy, reduce the levels of reactive oxygen species and malondialdehyde, and increase the levels of superoxide dismutase and glutathione peroxidase. It also improved albumin-induced mesenchymal transformation of renal tubular epithelial cells by reducing NADPH oxidase activity and inhibiting reactive oxygen cluster production.
4、Inhibit inflammatory response
Inflammatory cell infiltration and elevated level of inflammatory molecules are present in the occurrence and development of diabetic nephropathy, and some studies have suggested that diabetic nephropathy is an inflammatory disease caused by disorders of glucose and lipid metabolism. At present, it is believed that monocyte chemotactic protein-1 (MCP-1) is the main factor that causes various inflammatory cells, especially monocytes, to gather to the lesion site, and nuclear factor-κB (NF-κB) is one of the most important transcription factors that regulate the expression of MCP-1 gene. It was found that the dried powder of artificially fermented Cordyceps sinensis mycelium could inhibit NF-κB-mediated inflammation, reduce the infiltration of renal mononuclear macrophage, and decrease the deposition of fibronectin, thus exerting a nephroprotective effect, which was independent of the glucose-lowering effect.
Meanwhile, it was also found that Cordyceps sinensis powder could reduce the expression of renal interstitial macrophages and type IV collagen in rat kidney tissues, inhibit the infiltration of monocytes/macrophages in kidney tissues of diabetic rats, and inhibit the early inflammatory response of kidney tissues.
