Specific Gene Silencing Induces Apoptosis of HIV-Infected Macrophages

According to results of a genome-wide screening study published in BMC Infectious Diseases, silencing specific genes triggers apoptosis of HIV-infected macrophages and may be a viable curative approach for individuals with HIV infection.

Human monocyte cell lines (U937 and THP-1) were used to facilitate a pooled short hairpin RNA-based genome-wide screening of novel gene targets that induce apoptosis of macrophages infected with HIV-enhanced green fluorescent protein (eGFP) or HIV-heat stable antigen (HSA). Small interfering RNAs of target proteins were transfected into the cells, and apoptosis was assessed by flow cytometry.

The investigators observed that 28 genes were consistently associated with the survival of HIV-infected cells.

After transfection, apoptosis was induced (P <.1) in cells infected with HIV-eGFP and HIV-HAS with the silencing of 12 and 6 genes, respectively.

The investigators identified a final set of 4 of the top candidate genes that significantly increased apoptosis inducement (P <.05): the cytochrome c oxidase subunit 7A2 gene, COX7A2; the zinc finger protein 484 gene, ZNF484; the cyclin dependent kinase 2 gene, CDK2; and the cleavage stimulation factor subunit 2 tau variant gene, CSTF2T.

Compared with uninfected cells, knocking down COX7A2, ZNF484, CDK2, or CSTF2T caused up to 60% of infected macrophages and 15% of uninfected macrophages to undergo apoptosis. In addition, the investigators reported that some uninfected cells did not survive the transfection process, indicating that some of the cell death was likely due to transfection rather than gene silencing.

The investigators assessed whether gene silencing induces apoptosis in HIV-exposed cells. Compared with uninfected cells, the HIV bystander cells transfected with COX7A2, CDK2, or CSTf2T demonstratedsignificantly increased apoptosis inducement (15% vs 10%), though to a lesser extent than infected cells (50% vs 10%).

The investigators observed that silencing COX7A2 interfered with respiratory chain complexes II and IV and increased reactive oxygen species production.

This study was limited as it remains unclear whether these findings will translate into effective clinical interventions for individuals with HIV infection.

These data indicate the potential for gene-targeted silencing to induce apoptosis, specifically among HIV-infected cells.

Reference

Dong SXM, Vizeacoumar FS, Bhanumathy KK, et al. Identification of novel genes involved in apoptosis of HIV-infected macrophages using unbiased genome-wide screening. BMC Infect Dis. 2021;21(1):655. doi:10.1186/s12879-021-06346-7