Renal injury progression in autosomal dominant polycystic kidney disease: a look beyond the cysts.

Hypertension and progressive decline of renal function are among the common clinical manifestations in autosomal dominant polycystic kidney disease (ADPKD). At present, cyst formation in ADPKD patients is still considered the main pathogenic mechanism for the onset of these manifestations. However, the presence of polycystins in the vessels and the cilia of the endothelial cells and vascular smooth muscle cells, as well as development of hypertension prior to renal function decline and its prognostic role for the latter, indicate that polycystins may have an important role for endothelial damage in several vascular beds. Pathological polycystins induce intracellular calcium abnormalities, which affect various cellular organelles and functions and possibly lead not only to several abnormal biochemical reactions within endothelial cells, but also to an imbalance between oxidant and antioxidant capacity. Among the consequences of this process is accumulation of asymmetric-dimethylarginine, which not only participates in the induction and progression of renal damage, but also interferes with the normal vascular response due to nitric oxide (NO) inhibition. Reduced NO bioavailability would result in the long-run in relative vasoconstriction, impaired renal blood flow and vascular remodelling. This review summarizes the existing data from studies supporting that mechanisms other than cyst formation also contribute to the pathogenesis of hypertension and renal function decline in ADPKD.