Protective effects of tadalafil on damaged podocytes in an adriamycin-induced nephrotic syndrome model.

Podocyte injury is responsible for nephrotic syndrome. Previously, we found that tadalafil, a phosphodiesterase 5 inhibitor, might have protective effects on podocytes. Here, we investigated the effects of tadalafil in a nephrotic syndrome model and human podocyte cells. We divided adriamycin (ADR)-induced nephrotic syndrome model rats into the following groups: control + vehicle, control + tadalafil, ADR + vehicle, and ADR + tadalafil. The tadalafil-treated groups were orally administered 10 mg/kg tadalafil for 2 weeks. Renal parameters were measured. Immunohistology and immunofluorescence assays of glomerular injury were performed. Human primary podocytes were treated with or without tadalafil, and ADR. Cell viability and permeability assays were performed. ADR + vehicle exhibited severe proteinuria compared with control + vehicle and control + tadalafil. ADR + tadalafil attenuated proteinuria compared with ADR + vehicle. Wilms' tumor 1 (WT1) immunostaining revealed that the number of WT1-positive cells was decreased by ADR; however, this decrease was prevented by ADR + tadalafil. In human podocytes, tadalafil increased the viability of ADR-treated cells, which was abrogated by KT5823, a cGMP-dependent protein kinase (PKG) inhibitor. Moreover, tadalafil prevented albumin permeability in ADR-treated cells. ADR treatment alone increased the permeability of albumin compared with the control. Tadalafil might inhibit kidney injury progression by preventing damage to podocytes and dysfunction of the glomerular filtration barrier.