Arteriolar hyalinosis and arterial hypertension as possible surrogate markers of reduced interstitial blood flow and hypoxia in glomerulonephritis

BackgroundIn glomerulonephritis the final common pathway to end-stage renal disease (ESRD) is tubulo-interstitial damage (TID) whose main determinants are proteinuria and hypoxia consequent to haemodynamic and vascular alterations that reduce interstitial blood flow. Since oxygen tension is difficult to measure in human disease, arteriolar hyalinosis and arterial hypertension have been considered as possible surrogate markers of interstitial hypoxia. MethodsThe relationship between TID and arteriolar hyalinosis and arterial hypertension was evaluated in 132 IgA nephropathy (IgAN) and 79 idiopathic membranous nephropathy (IMN) patients. At biopsy tubulo-interstitial damage and arteriolar hyalinosis score were semi-quantitatively evaluated; urinary protein/creatinine ratio (P/C), fractional excretion (FE) of 1-microglobulin, urinary -NAG/creatinine ratio (NAG/C/eGFR) and urinary SDS-PAGE pattern were measured. ResultsIn IgAN arteriolar hyalinosis (AH) score correlates with TID score (P<0.0001), FE 1m (P=0.004) and NAG/C/eGFR (P=0.001), but not with P/C (P=0.10). Patients with or without AH were different in terms of global glomerulosclerosis (GGS: P<0.001), TID score (P<0.001), FE 1m (P=0.015), NAG/C/eGFR (P=0.002), but not of P/C (P=0.19). In IMN AH score correlates with TID score (P<0.0001), FE1m (P=0.04), NAG/C/eGFR (P=0.001), SDS-PAGE pattern (P=0.018), but not with P/C (P=0.10). Patients with or without AH were different in term of GGS% (P=0.05), TID score (P=0.001), FE 1m (P=0.039), NAG/C/eGFR (P=0.001), SDS-PAGE pattern (P=0.02), but not of P/C (P=0.065). Similar results for normal versus high blood pressure. ConclusionsArteriolar hyalinosis and arterial hypertension, associated with TID and GGS, factors that reduce interstitial capillary bed and blood flow, may be considered as reliable surrogate markers of hypoxia and co-determinants of TID. Summary at a Glance Arteriolar hyalinosis in IgA nephropathy and membranous nephropathy was significantly associated with tubulointerstitial damage severity, and this can be a surrogate marker of hypoxia.