Dysregulation of immunoexpression of matrix metalloproteinases in renal chronic allograft injury

The aim of the study was to evaluate tubulointerstitial immunoexpression of MMPs and TIMPs in chronic renal allograft injury, and to assess any relationships between immunoexpression of MMPs and interstitial monocytes/ macrophages and mast cells. Immunohistochemistry with antibodies against MMP-2, MMP-2, MMP-12, TIMP-1, TIMP-2, CD68, and mast cells tryptase was carried out on 17 renal biopsy specimens from patients with chronic allograft injury, and on 11 control kidney tissues. In renal specimens in chronic allograft injury increased expression of MMP-2, MMP-12 and TIMP-1 was noted. The immunoexpression of MMP-9 and TIMP-2 was low, and did not differ in comparison with controls. Increased immunoexpression of MMP-12 was positively correlated with the number of interstitial CD68+ cells. The correlation between immunostaining of MMP-12 and mast cells tended to be positive, however it did not reach statistical significance. There were significant positive correlations between immunostaining of MMP-9 and CD68+ cells, as well as between MMP-9 and the number of mast cells. In conclusion our study revealed that the remodelling of kidney structure in patients with chronic allograft injury is associated with dysregulation of MMPs and TIMPs, and may suggest that interstitial monocytes/macrophages and mast cells may cooperate with MMPs in pathogenesis of renal fibrosis.