HIV-1 GP120 ENVELOPE PROTEIN AND MORPHINE-TUBULAR CELL-INTERACTION PRODUCTS MODULATE KIDNEY FIBROBLAST PROLIFERATION

Background: Renal interstitial scarring is an important feature of HIV -associated nephropathy. Intravenous drug abuse has been demonstrated to be a risk factor for the development of HIV-associated nephropathy in patients with HIV infection. We studied the effect of tubular cell- morphine and/or HIV-1 gp120 envelope protein interaction products on k idney fibroblast (KF) proliferation and apoptosis. Methods: Tubular ce ll-morphine and/or gp120 interaction products were prepared by incubat ing confluent human proximal tubular cells with buffer (TCP), morphine (10(-8) mol/L) (TCM-IP), gp120 (0.01 mu g/mL)(TC-120IP), or morphine (10(-8) mol/L) + gp120 (0.01 mu g/mL) (TCM-120IP). To evaluate the eff ect of tubular cell interaction products (TCIP) on KF proliferation, g rowth arrested kidney fibroblasts were treated with variable concentra tions (5%, 10%, 20%, 30%, and 50%) of TCP, TCM-IP, TC-120IP, or TCM-12 0IP for 48 hours. To evaluate the role of cytokines in TCIP-induced KF proliferation, cells were incubated with TCIP with or without cytokin e neutralizing antibodies to TGF-beta, TNF-alpha, FGF, or IL-6 for 48 hours. Subsequently, cells were counted in a hemocytometer (n = 3). To evaluate the effect of TCIP on KF apoptosis, cells were treated with 50% TCP, 50% TCM-IP, 50% TC-120IP, or 50% TCM-120IP for 24 hours and s tained with H-33342 and propidium iodide. In parallel experiments KFs were harvested under identical conditions, DNA was isolated and run on gel electrophoresis. To evaluate the role of early growth genes in TC M-120-induced KF proliferation, TCM-120IP-treated cells were probed wi th cDNA for c-fos and c-jun. Results: TC-120IP at a lower concentratio n (20%) enhanced (P < 0.001) proliferation of KF when compared with TC P. TCM-IP did not stimulate KF proliferation. On the contrary, TCM-120 IP at a lower concentration (20%) promoted (P < 0.001) KF proliferatio n when compared with TCP, TCM-IP and TC-120IP. TCM-120IP at a lower co ncentration (20%) also enhanced KF mRNA expression of c-fos and c-jun. TCM-120IP enhanced KF proliferation in a dose-dependent manner. All t ubular cell interaction products at a higher concentration (50%) promo ted apoptosis of ICF. Conclusions: Tubular cell-gp120 interaction prod ucts stimulated KF proliferation. Morphine amplified the effect of tub ular cell-gp120 interaction on the proliferation of KF. TCM-120IP-indu ced KF proliferation may be mediated through the expression of early g rowth genes; whereas TCM-120IP-induced KF growth suppression may be me diated through the induction of apoptosis.