Toll-like receptor-3 mediates HIV-1 transactivation via NFκB and JNK pathways and histone acetylation, but prolonged activation suppresses Tat and HIV-1 replication

Abstract

TLR3 has been implicated in the pathogenesis of several viral infections, including SIV- and HIV-1-induced inflammation and AIDS. However the molecular mechanisms of these TLR3-mediated effects are not known, and it is not known whether HIV interacts with cellular TLR3 to affect disease process. Here we investigate the effects of TLR3 ligands on HIV-1 transactivation using both primary human macrophages and cells containing integrated copies of the HIV-1 promoter. We demonstrate that TLR3 activation induced upregulation of transcription factors such as c-Jun, CCAAT/enhancer-binding protein alpha (CEBPA), signal transducer and activator of transcription (STAT)-1, STAT-2, RELB, and nuclear factor kappa-B1 (NFκB1), most of which are known to regulate the HIV promoter activity. We also demonstrate that TLR3 activation increased HIV-1 transactivation via the c-Jun N-terminal kinase (JNK) and NFκB pathways. This was associated with epigenetics modifications, including decreased histone deacetylase activity, increased histone acetyl transferase (HAT) activity, and increased acetylation of histones H3 and H4 at lysine residues in the nucleosome-0 and nucleosome-1 of the HIV-1 promoter. However, prolonged TLR3 activation decreased HIV-1 transactivation, decreased HAT activity and Tat transcription, and suppressed viral replication. Overall, data suggests TLR3 can acts as viral sensor to mediate viral transactivation, cellular signaling, innate immune response, and inflammation in HIV-infected humans. Our study provides novel insights into the molecular basis for these TLR3-mediated effects.

Data in support of NFκB and JNK pathways involvement in TLR3-mediated HIV-1 transactivation, expression of IL-6 and transcription factors associated with HIV-1 replication

“…We further show the effects of TLR3 ligands on HIV-1 transactivation and transcription factors involved in HIV-1 replication. This article complements the data reported by the authors, “Toll-Like receptor-3 mediates HIV-1 transactivation via NFκB and JNK pathways, and histone acetylation, but prolonged activation suppresses Tat and HIV-1 replication” (Bhargavan et al, 2015) [1] , and the interpretation of these data can be found in the research article published by the authors in Cellular Signaling in 2015 (Bhargavan et al, 2015) [1] .…”

“…Human MDM were obtained from freshly elutriated human monocytes as previously described [1] , [2] , cultured in 6-well plates (2 million cells per well), and treated with 10 or 25 μg/ml PIC for 2–120 h, with each experimental condition performed in triplicate. In separate experiments, MDM were infected with HIV-1 ADA at a multiplicity of infection of 0.01 as previously described [1] , [2] , [3] , [4] , with or without PIC treatment (10 and 25 µg/ml) for 2–120 h, with each experimental condition performed in triplicate. Following treatment, cells were harvested, total RNA was extracted using the Trizol reagent, and real-time PCR performed as described in the main manuscript [1] .…”

“…In separate experiments, MDM were infected with HIV-1 ADA at a multiplicity of infection of 0.01 as previously described [1] , [2] , [3] , [4] , with or without PIC treatment (10 and 25 µg/ml) for 2–120 h, with each experimental condition performed in triplicate. Following treatment, cells were harvested, total RNA was extracted using the Trizol reagent, and real-time PCR performed as described in the main manuscript [1] . All PCR reagents, probes and primers were from Applied Biosystems and primers IDs were as follows: CEBPA (Hs00269972_s1), CEBPG (Hs01922818_s1), JUN (Hs99999141_s1), STAT1 (Hs00234829_m1), RELB (Hs00232399_m1), IL-6 (Hs00985639), and GAPDH (Hs99999905_m1).…”

Influenza A Viruses Replicate Productively in Mouse Mastocytoma Cells (P815) and Trigger Pro-inflammatory Cytokine and Chemokine Production through TLR3 Signaling Pathway

“…This data suggested that activated TLR3 pathways were responsible for the production of key pro-inflammatory cytokines and chemokines in IAV infected mast cells. A recent study suggested that TLR3 could act as viral sensor to mediate viral transactivation via upregulation of transcription factors such as c-Jun, which was known to regulate the viral promoter activity (Bhargavan et al, 2016). We recently also showed that IAV infection up-regulated c-jun expression and activation (Xie et al, 2014).…”

Proceedings from the NIMH symposium on “NeuroAIDS in Africa: neurological and neuropsychiatric complications of HIV”

“…Data revealed that Tat-AG had marginal effects on the blood-brain barrier, whereas Tat-B induced transcriptional upregulation of proinflammatory chemokines, complement components C3, C7, and factor-B, matrix metalloproteinases (MMP)-3, MMP-10, MMP-12; and also increased the activity of these MMPs in a dose-dependent manner (Woollard et al, 2014). Additionally, preliminary data also showed increased replication and transactivation of HIV-1 CR02_AG in macrophages that was associated with increased acetylation of histone proteins and histone acetyl transferase activity (Bhargavan et al, 2016). More studies in HIV infected individuals from Cameroon are underway to shed light on the effects of HIV subtype on viremia and neurocognitive impairment.…”