This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The introduction of HAART regimens (Highly Active Antiretroviral Therapy) has significantly modified the course of HIV disease, with longer survival rates and improvement of life quality in HIV-infected individuals. However, complete eradication of HIV infection cannot be achieved with currently available antiretroviral regimens. This primarily results from the establishment of a pool of latently infected CD4+ T cells, macrophages, and other host cells (eg. dendritic cells, mast cells) during the very earliest stages of acute HIV infection that persists with an extremely long half-life. This persistence of HIV-1 within various host immune cells, including macrophages constitutes a major obstacle in the control of HIV-1 infection. We are using model T cell and macrophage systems to evaluate the capacity of the oral microbial challenges to reactivate HIV. Our initial studies have used the BF24 cell line, a human macrophage transfected with the HIV LTR promoter driving a chloramphenicol acetyltransferase (CAT) gene.
Specific Aim 1 was to examine the alteration of these cells were challenged with oral bacteria (Pg, Sm, Cr, Fn) or sonicates to assess variations in HIV promoter activation related to species, dose, and time. We also evaluated the ability of a polymicrobial challenge to synergize in this activation. The outcome was measured using a CAT ELISA. Differences were noted in the ability of the various oral bacteria and bacterial sonicates to activate HIV, supporting that the characteristics of oral infection in periodontitis patients could variably impact reactivation of HIV. We also noted that a polybacterial challenge of the BF24 cells demonstrated an additive reactivation when compared to either bacterium alone.
Specific Aim 2 focuses on the ability of host induced molecules to reactivate HIV. In these studies, we have challenged human gingival fibroblast (HGF) cultures with various bacterial sonicates. The resulting supernatants were then used to stimulate HIV reactivation in the BF24 cells. The findings indicated a dose and time responsiveness for the HGF supernatants to stimulate the BF24 cells. However, these reactions appeared substantially less that direct bacterial stimulation of the macrophages. Finally, we have initiated some co-culture experiments in which the HGF, macrophages and bacterial challenge take place in the same milieu. Initial results suggest that factors in these cultures may actually modulate the ability to activate the HIV promoter. Thus, the data demonstrate that oral bacteria have the capacity to activate HIV in latently infected macrophages. There appeared some specificity to the magnitude of this activation and a polybacterial challenge of these infected cells can enhance HIV reactivation. The results suggest chronic oral infections provide a risk to treatment success in HIV infected patients.
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