The persistent HIV reservoir includes latently infected cells, which upon antiretroviral treatment (ART) interruption, reactivate HIV-1 expression and fuel rebound of disease progression. People living with HIV, even on ART, experience chronic inflammation associated with accelerated aging and comorbidities of the central nervous system, gut, and heart. The persistent reservoir is mostly composed of defective proviral genomes, unable to produce infectious virus due to deleterious mutations. However, the contribution of these defective viruses to chronic disease has not been well characterized. We have demonstrated that an intragenic element in the Env region of the HIV genome drives transcription of non-canonical RNA in defective proviruses. We hypothesize that these transcripts from defective proviruses contribute to chronic inflammation.
To model defective proviruses, we used CRISPR-Cas9 to engineer cells harboring HIV genomes with a nonfunctional 5’ LTR.
We observed a correlation between levels of internally driven transcripts and in vitro pro-inflammatory cytokine production in Jurkats, macrophage-like ThP1 cells, and cells differentiated into macrophages. Additionally, we confirmed nuclear export of these transcripts and that shRNA-mediated MAVS knockdown in ThP1s decreases the inflammatory response.
We propose a model that innate immune sensing of these transcripts activates a MAVS-dependent pathway to contribute to chronic inflammation and HIV-associated comorbidities.
NIH RO1 AI187175, NIH RO1 AI138960, NIH RO1 DA055488, CFAR P30AI042853, Boston University Undergraduate Research Opportunities Program Faculty Matching Grant
Viral Immunology (VIR)
Aparna Deokar, Jonathan Kilroy, H. Akiyama et al.· Journal of Immunology· 0 citations
ABSTRACT The persistent HIV-1 reservoir includes a subset of cells harboring transcriptionally repressed latent HIV-1 that contributes to rebound upon antiretroviral treatment (ART) interruption. However, the majority of the reservoir consists of defective proviral genomes with mutations that prevent production of HIV-1 virions. People with HIV (PWH), even with suppression of viremia, demonstrate comorbidities of the central nervous system, heart, gut, and general aging-associated inflammation. Previously, we identified a transcriptionally active element within the envelope gene (env) of HIV-1, which mediates the expression of aberrant HIV-1 RNAs. We hypothesize that spurious expression of defective proviruses contributes to the general inflammation that drives these comorbidities. We observed correlations between levels of inflammatory cytokines in serum of PWH and levels of HIV-1 transcripts from this intragenic promoter. To investigate the impact of defective proviruses, we employed CRISPR-Cas9 to render the 5′ long terminal repeat (LTR), which acts as the enhancer and promoter for proviral transcription, non-functional. HIV-1-infected cells harboring this deletion produce significantly higher levels of IP-10 and IL-8 in vitro in both monocytic cell lines and primary monocyte-derived macrophages. Transcripts generated from the env promoter include a 5′ cap and polyA tail, and the induction of IP-10 expression was dependent on the cytosolic innate immune sensing pathway components MDA5 and MAVS and not cGAS and RIG-I. We propose that defective HIV proviruses contribute to chronic inflammation in PWH through an MDA5-dependent induction of type I interferon pathways. IMPORTANCE People with HIV-1 are at higher risk of developing age-associated comorbidities and immune exhaustion even when receiving antiviral treatments and having no detectable viremia. Transcription and translation have been documented from latent and defective proviruses, but their impact on inflammation associated with chronic HIV-1 infection remains poorly understood. The significance of this work is in identifying a role for defective HIV-1 proviruses and correlating their transcription in triggering a type I interferon response. These results highlight the importance of the persistent defective HIV-1 proviruses and understanding their impact on driving chronic inflammation to inform future strategies to assure people with HIV-1 healthy living and aging. People with HIV-1 are at higher risk of developing age-associated comorbidities and immune exhaustion even when receiving antiviral treatments and having no detectable viremia. Transcription and translation have been documented from latent and defective proviruses, but their impact on inflammation associated with chronic HIV-1 infection remains poorly understood. The significance of this work is in identifying a role for defective HIV-1 proviruses and correlating their transcription in triggering a type I interferon response. These results highlight the importance of the persistent defective HIV-1 proviruses and understanding their impact on driving chronic inflammation to inform future strategies to assure people with HIV-1 healthy living and aging.
Jonathan Kilroy, Aparna Deokar, Samantha Patalano et al.· Journal of Virology· 0 citations