Protective Mechanism of Qi-Dan-Dihuang Decoction in Diabetic Kidney Disease Based on Network pharmacology

Background: Qi-Dan-Dihuang Decoction (QDD) has been used for treating diabetic kidney disease (DKD), but the mechanisms are poorly understood. The aim of this study is to reveal the therapeutic effects and the mechanism of QDD in ameliorating DKD by network pharmacology, in vivo, and in vitro studies.Methods: The effect of QDD on body weight, fast blood glucose, oral glucose tolerance test (OGTT), 24 h urinary protein (24hU-Pro), serum creatinine (Scr), blood urea nitrogen (BUN), and pathological evaluation in kidney were investigated in vivo using C57BLKS/J db/db mice. The main active compounds of QDD, compound-disease interaction targets, and related processes and pathways were discerned by network pharmacology analysis through Chinese Medicine Systems Pharmacology Database (TCMSP) and TCM Database@Taiwan. The protein-protein interaction (PPI) network were established through STRING database. GO and KEGG pathway were used for analysis processes and pathways. Then Western blot was used to verified the predicted results. Finally, cell viability, wound healing and mainly pathway protein expression were detected in vitro using renal tubular epithelial cells HK-2 and NRK-52E cells.Results: Although QDD treatment showed no significant difference in FBG and AUC of OGTT, but had significant reduction in Scr level in C57BLKS/J db/db mice. Histopathologic results showed that QDD ameliorated the expansion of mesangial area, thickened membranes of Bowman’s capsules and basement membrane of glomerular capillaries, renal tubular epithelial cells vacuolar degeneration and reversed the glomerular and tubulointerstitial in C57BLKS/J db/db mice. For network pharmacology analysis of QDD, 143 active compounds related to 274 possible targets in QDD obtained and 117 compound-disease interaction targets were screened out combining with Genecards database. 18 key targets was excavated through network topological analysis. GO and KEGG pathway enrichment analysis showed that compound-disease interaction targets were significantly enriched in processes and pathways that are closely related to DKD. Western blot results showed that QDD significantly attenuated EMT-related proteins, p-NF-κb, IL-1β, IL-18, p-p38MAPK/p38MAPK, p-AKT/AKT, and p-mTOR/ mTOR protein expressions. Treatment with QDD could alleviate cell viability damaged, EMT process, p-NF-κb, IL-1β, IL-18, p-p38MAPK/p38MAPK, p-AKT/AKT and p-mTOR/ mTOR protein expressions by high D-gulcose.Conclusions: This study provides convincing evidence suggest that QDD protects renal fibrosis of DKD, by regulating EMT in RTECs and inflammatory response through p38MAPK and AKT/mTOR signaling pathways.