Effect Of HIF1?-KIM1 Pathway On Extracellular Matrix In Diabetic Nephropathy

Background and aim Diabetic nephropathy (diabetic nephrophy, DN) is one of the microvascular complications of diabetes with higher incidence, and it is also the main reason leading to end-stage renal disease (ESRD). Progressive renal interstitial fibrosis (renal interstitial fibrosis, RIF) is an important pathological basis of DN progression. Yet the mechanism of RIF has not been fully elucidated. Thus, to prevent and cure the incidence of diabetic nephropathy and delay its progress has become a medical research hotspot.Related researches home and abroad indicated that hypoxia inducible factor 1? (HIFla) could bind to the hypoxia response element of kidney injury molecule 1 (KIM1) promoter region and activate the expression of KIM1. HIF1? and KIM1 are closely related to the renal interstitial fibrosis. But the relevant research about HIFla-KIM1 pathway in DN is little.In this study, human proximal tubular epithelial cells (HK2) was cultured under high glucose in vitro. We observe the expression of HIF1?, KIM1 and extracellular matrix related indicators such as matrix metalloproteinase 9 (MMP9), tissue inhibitor of metalloproteinase 1 (TIMP1), fibronectin (FN) and type I collagen (COL-I). HIF? siRNA and KIM1 siRNA transfection method was used respectively, and the change of HIFla, KIM1, MMP9, TIMP1, FN and COL-I was observed. Aim to investigate the role of HIFla-KIM1 signaling pathway in RIF of diabetic nephropathy.Methods The human tubular epithelial cells (HK2) were cultured in vitro and divided into the following groups:1. Normal control Group (D-glucose 5.6 mmol/L); 2. Mannitol group (D-glucose 5.6 mmol/L+D-mannitol 24.4 mmol/L); 3. High glucose group (D-glucose 30 mmol/L); 4. Control siRNA group; 5. HIFla siRNA group; 6. KIM1 siRNA group. The corresponding indexes were measured at the 12th,24th and 36th hours. Western blotting, immunofluorescence and qRT-PCR were used to examine the expression of HIF1?,KIM1, MMP9, TIMP1, FN and COL-I in protein and mRNA level.Results Compared with the control group, the protein and mRNA expression of HIFla, KIM1, TIMP1, FN and COL-I in the high glucose group were increased in a time-dependent manner (P<0.05), and MMP9 was in time-dependent reduction (P<0.05). Compared with the high glucose group, the protein and mRNA expression of HIF1?,KIM1, TIMP1, FN and COL-I in HIFla siRNA group was decreased (P<0.05), and MMP9 was increased (P<0.05). However, the protein and mRNA expressions of KIM1, TIMP1, FN and COL-I in KIM1 siRNA group was decreased (P<0.05), MMP9 was increased (T<0.05), and the change of HIFla was of no significance (P>0.05)Conclusion Down regulation of HIFla can significantly inhibit the expression of KIM1 in HK2 and decrease the expression of extracellular matrix, and down-regulation of KIM1 could also decrease the extracellular matrix under high glucose, which suggests that HIF1? may regulate the expression of KJM1 in human tubular epithelial cells (HK2) under high glucose condition, and this pathway may participate in renal interstitial fibrosis of DN.