During the last period of the grant we have found an accumulation of heparin binding growth factors (HBGF) in the circulation and renal tissues of HIV-infected children and HIV-Tg rats/mice with HIV-associated nephropathy (HIVAN). Based on these data, we hypothesize that heparan sulfate proteoglycans (HSGP) located on the surface of renal epithelial cells sustain the infectivity of HIV-1 in the kidney, and increase the recruitment of HIV-Tat and HBGF inducing the proliferation of renal epithelial cells and progression of the renal disease. A second corollary of this hypothesis is that preventing the binding of circulating viral proteins and HBGF to renal HSPG will improve the clinical outcome of HIVAN.
Three aims will be studied:
AIM 1) To define the basic mechanisms by which HIV-Tat and gp120 modulate the growth of primary glomerular and tubular epithelial cells in an HIV-Tg rat model of childhood HIVAN, and define the role of HBGF in this process. To explore the role of gp120, we will generate HIV-Tg rats expressing an envelope mutated HIV-1 transgene. Primary podocytes and metanephric kidneys (MK) harvested from wild type (WT) and HIV-Tg rats, will be infected with adenoviral-Tat (rAd-Tat) or control vectors. These cells/MK will be followed in vitro, or transplanted under the renal capsule of adult WT or HIV-Tg rats, to determine their growth rate, and to define the role of circulating viral proteins/HBGF in this process.
AIM 2) To determine how HIV-Tat, Nef, and gp120, alone or in combination with HBGF, modulate the growth rate and differentiation of cultured primary podocytes and tubular epithelial cells harvested from children with and without HIVAN. We have developed new methods to culture differentiated podocytes from children with HIVAN, and to evaluate their growth rates after infection with rAd-Tat or Nef vectors, in the presence or absence of HBGF or gp120. We will also define whether primary human renal epithelial cells express HIV-1 viral products, and validate the results of AIM 1.
AIM 3) To determine whether pentosan polysulfate (PPS), alone or in combination with protease inhibitors (Pis), will improve the outcome of HIVAN by blocking the activity of Tat/HBGF in vivo, and/or by preventing the attachment, entry, and/or fusion of HIV-1 to cultured renal epithelial cells harvested from children with HIVAN. These studies will demonstrate that growth factors release into the circulation of HIV- infected children can accelerate the progression of HIVAN, and test new therapies against this disease.
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