Apoptosis resistance in HIV-1 chronicaly infected cells is not associated to viral replication or tat expression.

P.N. FERNÁNDEZ LARROSA, D. CROCI RUSSO, D. RIVA, M. BIBINI, R. LUZZI, M. SARACCO, G. RABINOVICH, S. MERSICH, L. MARTÍNEZ PERALTA.

Portoroz

Congreso; 15th Euroconference on Apoptosis & 4thTraining course on 'Concepts and Methods in Programmed Cell Death'.; 2007

European Cell Death Organisation

HIV triggers the decline 01 CD4+ T cel!s and leads to progressive dislunction 01 eell-mediated immunity, mainly during the aeute phase 01 HIV inlection. On the other hand, chronically-inlected macrophages and memory T-cel!s seem to be resistan! to cell death, representíng a potential viral reservoir. In order to analyse the effects 01 HIV-1 over reservoir cel!s, persistently infected cel!s were treated with different apoptosis inducers and results were compared with those uninfeeted cells. Unínleeted cell lines(H9, Jurkat, U937) and their HIV-1 persistently infected counterparts (H9/HTLVIIIB, J1.1, U1) were treated with HzOz or staurosporine (STS) and collected 24 hours post treatment. Cells were treated with medium as eontrols (Ctrl). Tat-transfeeted Jurkat cells (JurkaHat) were also treated with inducers in order to evaluate the elfeet 01 tat over apoptosis susceptibility. Cell death parameters were evaluated by annexin-V/PI or APO-BRDU staining and FACS. P24 antigen production was quantilied. Western Blot analyses were performed to evaluate apoptosis proteins. When treated with both inducers, persistently infeeted cel!s showed significantly lower apoptosis levels than uninfeeted cel!s. Infected cel!s showed significant decrease in the levels of p24 production when subjected to both treatments. Neither the induction of viral production in J1.1 with TNF-o and U 1 with PMA, nor expression of tat, marked significant differences in cell viability with respect to uninduced cells. Bax levels were higher deereased_(HzOz: 40%; STS: 70%) In H9/HTLVIIIB cel!s treated with apoptosis inducers than in H9 cel!s (HzOz: 20%;STS: 40%), while no differenee in BcI-2 expression was observed in both cell lines. Besides H9 eells treated with STS showed an important decrease of procaspase- 3 (70%): indieating high levels 01 cleavage; eompared to H9/HTLVIIIB (40%). Our results suggest that, when treated with HzOz and STS, persistently infected cell lines were more resistant to dying by apoptosis compared with uninfeeted cell lines, and this effeet was independent of aclive viral replication or tat expression. This resislance could be regulated at lhe mitochondrial level via Bcl-2/Bax balance. This in vitro resistance could help to understand the in vivo HIV reservoir persistence.