Showing papers by "Phalguni Gupta published in 2019"

Inhibitors of Signaling Pathways That Block Reversal of HIV-1 Latency

Abstract: Signaling pathways play a key role in HIV-1 latency. In this study, we used the 24ST1NLESG cell line of HIV-1 latency to screen a library of structurally diverse, medicinally active, cell permeable kinase inhibitors, which target a wide range of signaling pathways, to identify inhibitors of HIV-1 latency reversal. The screen was carried out in the absence or presence of three mechanistically distinct latency-reversing agents (LRAs), namely, prostratin, panobinostat, and JQ-1. We identified inhibitors that only blocked the activity of a specific LRA, as well as inhibitors that blocked the activity of all LRAs. For example, we identified 12 inhibitors targeted toward protein kinase C or downstream kinases that blocked the activity of prostratin. We also identified 12 kinase inhibitors that blocked the reversal of HIV-1 latency irrespective of the LRA used in the screen. Of these, danusertib, an Aurora kinase inhibitor, and PF-3758309, a PAK4 inhibitor, were the most potent. The 50% inhibitory concentrations in the 24ST1NLESG cells ranged from 40 to 147 nM for danusertib (selectivity indices, >150) and from 0.1 to 1 nM for PF-3758309 (selectivity indices, >3,300). Both danusertib and PF-3758309 inhibited latency reversal in CD4+ T cells isolated from HIV-1-infected donors. Collectively, our study describes a chemical approach that can be applied to elucidate the role of signaling pathways involved in LRA activity or the maintenance of HIV-1 latency and also identifies inhibitors of latent HIV-1 reactivation that could be used with antiretroviral therapy to reduce residual viremia.

Neisseria gonorrhoeae uses cellular proteins CXCL10 and IL8 to enhance HIV-1 transmission across cervical mucosa.

Abstract: Problem Neisseria gonorrhoeae (NG) infection has been shown to increase sexual transmission of HIV-1. However, the mechanism of NG-induced enhanced HIV-1 transmission is unknown. Methods (a) The cervical tissues were exposed to NG, and cytokine induction was monitored by measuring cytokine proteins in culture supernatants and cytokine mRNAs in tissues. (b) Transcription and replication of HIV-1 in TZM-bl, U1, and ACH2 cells were measured by Beta-Gal activity and p24 proteins in the supernatant, respectively. (c) HIV-1 transmission was assayed in an organ culture system by measuring transmitted HIV-1 in supernatant and HIV-1 gag mRNA in the tissues. (d) Transcriptome analysis was done using second generation sequencing. Results (a) NG induced membrane ruffling of epithelial layer, caused migration of CD3+ cells to the intraepithelial region, and induced high levels of inflammatory cytokines IL-1β and TNF-α. (b) NG-induced supernatants (NGIS) increased HIV-1 transcription, induced HIV-1 from latently infected cells, and increased transmission of HIV-1 across cervical mucosa. (c) Transcriptome analysis of the epithelial layer of the tissues exposed to NG, and HIV-1 showed significant upregulation of CXCL10 and IL8. IL-1β increased the induction of CXCL10 and IL-8 expression in cervical mucosa with a concomitant increase in HIV-1 transmission. Conclusion We present a model in which IL-1β produced from cervical epithelium during NG exposure increases CXCL10 and IL8 in epithelia. This in turn causes upon HIV-1 infection, the migration of HIV-1 target cells toward the subepithelium, resulting in increased HIV-1 transcription in the sub-mucosa and subsequent enhancement of transmission across cervical mucosa.

TZA, a Sensitive Reporter Cell-based Assay to Accurately and Rapidly Quantify Inducible, Replication-competent Latent HIV-1 from Resting CD4+ T Cells.

Abstract: The latent HIV-1 viral reservoir in resting CD4+ (rCD4+) T cells represents a major barrier to an HIV-1 cure. There is an ongoing effort to identify therapeutic approaches that will eliminate or reduce the size of this reservoir. However, clinical investigators lack an assay to determine whether or not a decrease in the latent reservoir has been achieved. Therefore, it is critical to develop assays that can reproducibly quantify the reservoir size and changes therein, in participant's blood during a therapeutic trial. Quantification of the latent HIV viral reservoir requires a highly sensitive, cost-effective assay capable of measuring the low frequency of rCD4+ T cells carrying functional provirus. Preferably, such an assay should be such that it can be adopted for high throughput and could be adopted under conditions for use in large-scale clinical trials. While PCR-based assays are commonly used to quantify pro-viral DNA or intracellular RNA transcript, they cannot distinguish between replication-competent and defective proviruses. We have recently published a study where a reporter cell-based assay (termed TZA or TZM-bl based quantitative assay) was used to quantify inducible replication-competent latent HIV-1 in blood. This assay is more sensitive, cost-efficient, and faster than available technology, including the quantitative viral outgrowth assay or the Q-VOA. Using this assay, we show that the size of the inducible latent HIV-1 reservoir in virally suppressed participants on ART is approximately 70-fold larger than previous estimates. We describe here in detail an optimized method to quantitate latently infected cells using the TZA.