Podocytes in HIV-associated nephropathy

HIV-associated nephropathy (HIVAN) is the leading cause of end-stage renal failure in HIV-1 seropositive patients. The pathologic findings include collapsing focal segmental glomerulosclerosis with proliferation of epithelial cells in Bowman's space. Anatomically, these cells correspond to podocytes and exhibit a unique phenotype with loss of many differentiation markers including synaptopodin and dysregulation of the cell cycle markers consistent with proliferation. Podocyte dysfunction appears to be a direct result of HIV-1 protein expression, specifically Nef and Vpr as well as specific host factors that have yet to be elucidated. The mechanism by which Nef induces podocyte proliferation and dedifferentiation has been traced to its ability to activate several signaling pathways including Src-Stat3 and ras-raf-MAPK1, 2. Activation of the cAMP/PKA pathway with all-trans-retinoic acid appears to modulate these changes and returns podocytes to a differentiated, nonproliferating phenotype.