Stromal cell-derived factor-1α suppressese the expression of type IV collagen in human renal proximal tubular epithelial cells in high glucose

Objective To explore the effect of stromal cell-derived factor-1α(SDF-1α) on extracellular matrix (type Ⅳ collagen) in human renal proximal tubular epithelial cells (HKC) with the different glucose conditions. Methods HK cell were cultured exposed to SDF-1α and transform growth factor-β1(TGF-β1) of the different concentration with normal (NG group: 5.5 mmol/L glocuse) or high (HG group:25.0 mmol/L glucose) glucose. With the stimulation of TGF-β1 and SDF-1α for 12 hours later, the HKC were divided to the following groups: control group(NC group), S group (SDF-1α alone),T group (TGF-β 1 alone),S+T group(SDF-1α and TGF-β1 together). Real-time PCR and Western blotting were used to detect the m RNA and protein expression of type Ⅳ collagen in HKC. Comparison between two groups was using t test. Results (1)The m RNA expression of SDF-1α and CXCR4 mRNA was detected continuously in HKC. High glucose could increase the expression of SDF-1α and CXCR4 mRNA in HKC with a time-dependent manner, which reached the highest level at 24 h. The mRNA level of CXCR4 at 24 h was 1.2 times of those at 12 h(t=6.08, P<0.05), meanwhile the mRNA level of SDF-1α at 24 h was 1.58 times of those at 12 h(t= 7.52, P<0.05). (2)With high glucose SDF-1α suppressed the mRNA and protein expression of type Ⅳ collagen induced by TGF-β1 in HKC. The mRNA and protein expression level of type Ⅳ collagen in S+T group were 0.33 times(t=12.57, P<0.05), and 0.47 times(t=14.23,P<0.05)of those in T group, respectively. Under the normal glucose condition, SDF-1α had no effect on the expression of type Ⅳ collagen induced by TGF-β1.(3)TGF-β1 stimulated mRNA and protein expression of type Ⅳ collagen in HKC, especially in high glucose. The mRNA and protein expression level of type Ⅳ collagen in T group were 6.63 times(t= 19.21, P<0.05),and 2.59 times(t=15.71, P<0.05)of those in control group respectively. Conclusions (1) SDF-1α maybe attenuate the renal fibrosis by suppressing the expression of type Ⅳ collagen induced by TGF-β1 in high glucose.(2)TGF-β1 promotes the development of DN by increasing the expression of type Ⅳ collagen in HKC. Key words: Diabetic nephropathy; Diabetes mellitus type 2; Stromal cell derived factor-1; Type Ⅳ collagen