Dendritic cells maturated by co-culturing with HIV-1 latently infected Jurkat T cells or stimulating with AIDS-associated pathogens secrete TNF-α to reactivate HIV-1 from latency.

Elucidation of mechanisms underlying the establishment, maintenance of and reactivation from HIV-1 latency is essential for the development of therapeutic strategies aimed at eliminating HIV-1 reservoirs. Microbial translocation, as a consequence of HIV-1-induced deterioration of host immune system, is known to result in a systemic immune activation and transient outbursts of HIV-1 viremia in chronic HIV-1 infection. How these microbes cause the robust HIV-1 reactivation remains elusive. Dendritic cells (DCs) have previously been shown to reactivate HIV-1 from latency; however, the precise role of DCs in reactivating HIV-1 from latently infected T-cell remains obscure. In this study, by using HIV-1 latently infected Jurkat T cells, we demonstrated that AIDS-associated pathogens as represented by Mycobacterium bovis (M. bovis) Bacillus Calmette-Guérin (BCG) and bacterial component lipopolysaccharide (LPS) were unable to directly reactivate HIV-1 from Jurkat T cells; instead, they mature DCs to secrete TNF-α to accomplish this goal. Moreover, we found that HIV-1 latently infected Jurkat T cells could also mature DCs and enhance their TNF-α production during co-culture in a CD40-CD40L-signaling-dependent manner. This in turn led to viral reactivation from Jurkat T cells. Our results reveal how DCs help AIDS-associated pathogens to trigger HIV-1 reactivation from latency.