Increased transforming growth factor beta (TGF-β) and pSMAD3 signaling in a Murine Model for Contrast Induced Kidney Injury

We tested the hypothesis that post-contrast acute kidney injury (PC-AKI) occurs due to increase in transforming growth factor beta (Tgf-beta) and pSMAD3 signaling in a murine model of PC-AKI. Mice had nephrectomy performed and twenty-eight days later, 100-mu L of radio-contrast (Vispaque 320) or saline was administered via the jugular vein. Animals were sacrificed at 2, 7, and 28 days later and the serum BUN, creatinine, urine protein levels, and kidney weights were assessed. In human kidney-2 (HK-2) cells, gene and protein expression with cellular function was assessed following inhibition of TGF beta R-1 plus contrast exposure. After contrast administration, the average serum creatinine is significantly elevated at all time points. The average gene expression of connective tissue growth factor (Ctgf), Tgf beta-1, matrix metalloproteinase-9 (Mmp-9), and collagen IVa (Col IVa) are significantly increased at 2 days after contrast administration (P < 0.05). Cellular proliferation is decreased and there is increased apoptosis with tubulointerstitial fibrosis. Contrast administered to HK-2 cells results in increased pSMAD3 levels and gene expression of Ctgf, Tgf beta-1, Tgf beta-2, Col IVa, Mmp-9, and caspase/7 activity with a decrease in proliferation (all, P < 0.05). TGF beta R-1 inhibition decreased the expression of contrast mediated pro-fibrotic genes in HK-2 cells with no change in the proliferation and apoptosis.