[The role of tubulointerstitial changes in progression of kidney function failure in patients with chronic glomerulonephritis (GN)]

Abstract

In most cases of glomerulonephritis (GN) long-term course lead to chronic renal failure. The cause of inevitably gradually progress of GN to end-stage renal disease (ESRD) is unclear. The histological abnormalities seen in patients with progressive renal failure consist of focal and segmental glomerulosclerosis and tubulointerstitial nephritis. At present it is considered that tubulointerstitial changes attends almost all forms of progressive glomerular and vascular injury. It was known that chronic tubulointerstitial nephritis is characterized morphologically by tubular atrophy, interstitial fibrosis and interstitial inflammation of variable severity. The pathomechanism of this changes is complicated. Tubular ischaemia results from obliteration of peritubular capillaries, adaptation of tubular function with increased oxygen consumption and increased glomerular capillary permeability to macromolecules are reasons of chronic tubular damage. Injured tubules release growth factors and cytokines, which induce interstitial fibroblast proliferation, chemo-attraction and proliferation of infiltrating cells, and disruption of the balance between synthesis and degradation of cellular constituents. The consequences of these processes are tubular atrophy and interstitial fibrosis. Because of many studies concurred that tubulointerstitial changes determinant the progression of GN, tubular injury markers were searched for. Although over 50 enzymes were detected in human urine, only a few have been used for diagnosis in renal disease. The most widely used are lysosomal enzyme N acetyl-beta-D-glucosaminidase (NAG) and brush border enzymes alanine-aminopeptidase (AAP) and gamma-glutamyltransferase (GGT). tubular damage in hypertension, diabetes and in diagnostics of renal disease. AAP and GGT, brush border enzymes seem to be sensitive markers of renal injury too. Pathological value of GGT was observed even in the early stage of disease. Measurement of urinary excretion of low molecular weight proteins was valuable supplement in estimation of tubulointerstitial system malfunction. These proteins are readily filtered by normal glomeruli and virtually completely reabsorbed by normal proximal tubules. Favour are alpha-1-microglobulin (alpha-1-m) and retinol-binding protein (RBP) because they are less affected than beta-2-microglobulin (beta-2-m) by low urine pH. Above presented review confirm that further research in correlation between activity of disease, histological picture, deterioration in renal function and changes in urinary excretion of markers proteins (for example alpha-1-m, AAP, NAG, GGT) is advisable, and can contribute to use in clinic diagnostics of GN.