The renin- Angiotensin- Aldosterone System (RAAS) has been demonstrated to play an important role in the development and progression of renal lesions in both human and animal models of focal glomerulosclerosis (FGS). Interestingly, pharmaceutical agents which modulate the effects of Ang II have been the only ones investigated and proven to alter the course of HIV-associated nephropathy (HIVAN). Since inhibition of two other components of RAAS- eplerenone (a selective inhibitor of aldosterone) and aliskiren (a selective renin inhibitor) have also been reported to modulate the progression of renal lesions in non-HIVAN models of FGS, we hypothesize that use of these agents either alone or in combination with ACE (angiotensin I converting enzyme) inhibitors/AT1 receptor blockers will not only attenuate or prevent HIV-1-induced injury but also delay or slow down the progression of HIVAN. In preliminary studies, we observed that renal cells in mice transgenic HIV-1 genes (HIVAN mice, Tg26) not only showed activation of the mTOR pathway but also displayed enhanced epithelial mesenchymal transdifferentiation (EMT). Interestingly, aliskiren not only inhibited the activation of mTOR pathway as well as renal cell EMT but also attenuated HIVAN phenotype. Moreover, renal tissue of HIVAN (Tg26) mice showed six-fold increase in renin mRNA expression. These findings indicate that the activation of EMT and mTOR pathways in renal cells may be mediated either directly through renin or its downstream effector molecules such as Ang II. Since the activation of the RAAS (host factor) and or African descent (genetic factor) alone has not been shown to manifest into HIVAN phenotype in other renal disease models, it appears that manifestation of HIVAN phenotype requires specific environmental factors, such as renal cell expression of HIV-1 genes. Although, we can not change the ancestry but we can modulate the environmental (HIV-1 infection) and host factors. Based on our preliminary data, we hypothesize that modulation of RAAS by its selective inhibitors will not only prevent or attenuate HIV-1- induced renal injury but also delay or slow down the progression of HIVAN.
Patients infected with HIV-1 are prone to develop a rapidly progressing kidney disease termed HIV-associated nephropathy (HIVAN). HIVAN is the third leading cause of End-stage renal disease among individuals with African American background, and is associated with the highest rates of hospitalizations in this population. At present, there is no specific treatment to cure this disease. Since activation of Renin-Angiotensin- Aldosterone System plays an important role in the progression of renal diseases in general, we intend to evaluate the effect of its inhibition in HIVAN. Our long term research goal is to develop strategies to slow down the progression as well as find a cure of this devastating kidney disease.
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