Novel HIV-1 miRNAs stimulate TNFα release in human macrophages via TLR8 signaling pathway

To determine whether HIV-1 produces microRNAs and elucidate whether these miRNAs can induce inflammatory response in macrophages (independent of the conventional miRNA function in RNA interference) leading to chronic immune activation.

Using sensitive quantitative Real Time RT-PCR and sequencing, we detected novel HIV-derived miRNAs in the sera of HIV+ persons, and associated with exosomes. Release of TNFα by macrophages challenged with HIV miRNAs was measured by ELISA.

HIV infection of primary alveolar macrophages produced elevated levels of viral microRNAs vmiR88, vmiR99 and vmiR-TAR in cell extracts and in exosome preparations from conditioned medium. Furthermore, these miRNAs were also detected in exosome fraction of sera from HIV-infected persons. Importantly, vmiR88 and vmiR99 (but not vmiR-TAR) stimulated human macrophage TNFα release, which is dependent on macrophage TLR8 expression. These data support a potential role for HIV-derived vmiRNAs released from infected macrophages as contributing to chronic immune activation in HIV-infected persons, and may represent a novel therapeutic target to limit AIDS pathogenesis.

Novel HIV vmiR88 and vmiR99 are present in the systemic circulation of HIV+ persons and could exhibit biological function (independent of gene silencing) as ligands for TLR8 signaling that promote macrophage TNFα release, and may contribute to chronic immune activation. Targeting novel HIV-derived miRNAs may represent a therapeutic strategy to limit chronic immune activation and AIDS progression.