2072. Of Mice and Men: HIV-induced CD38 expression on CD8+ T lymphocytes contributes to mitochondrial dysfunction and chronic inflammation despite antiretroviral therapy

Abstract

Abstract Background Antiretroviral treatment (ART) has increased the life expectancy of people with HIV (PWH), however, comorbidities are higher in PWH than HIV-negative individuals. This is partly due to accelerated cellular aging, a consequence of CD38 expression, mitochondrial dysfunction, and inflammation. However, the role of CD38-expressing T cells on accelerated cellular aging in PWH is not completely understood. Methods The proportion of cytotoxic CD38+ CD8+ T lymphocytes from peripheral blood mononuclear cells (PBMCs) of PWH and HIV negative-individuals was measured. PBMCs from PWH on ART were cultured with or without gag-specific peptide stimulation and cytokine production was detected by flow cytometry. Mitochondrial function from T cells of PWH on ART and healthy donors was compared. Last, we generated a humanized (NSG) mouse model and infected mice with HIV (Bal strain) to determine the proportion of CD38+ T cells and cytokine production. Results Mean CD38 expression on CD8+ T cells was significantly different between PWH on ART and HIV-negative individuals (Figure 1). In PWH, gag-specific peptide stimulation of CD8+ T cells significantly increased CD38 expression (Figure 2A) and augmented secretion of IFNγ+ and TNFα+ (Figure 2B). There was a higher expression of CD38 among CD8+ T cells that produced IFNγ and TNFα (Figures 2C). T cells in PWH have altered mitochondrial function (Figures 2D-2F). Finally, HIV-infected NSG mice had T cell changes consistent with HIV infection (Figure 3A), a higher proportion of CD38+ T cells with an activated phenotype (Figures 3B and 3C), and significantly higher levels of inflammatory cytokines (Figure 3D). Figure 1.CD38 expression in PWH and HIV-negative individuals.Mean %CD38+CD8+ T cells in people with HIV (PWH) on and off antiretroviral therapy (ART) and HIV-negative individuals. Statistical significance was tested by Kruskal-Wallis test with post hoc analysis (Dunn’s Multiple comparison test). ****, P value< 0.0001.Figure 2.Cytokine production in response to gag stimulation from CD38+CD8+ T cells and mitochondrial function in T cells of PWH. Figure 2. (A) Frequency of CD38+ cells in gag-peptide stimulated CD8+ T cells and unstimulated cells. (B) Frequency of IFNγ and TNFα producing CD8+ T cells in gag-stimulated and unstimulated cells. Proportion of CD38+ cells among (C) IFNγ-/IFNγ+ and TNFα-/TNFα+ gag-peptide stimulated CD8+ T cells. Statistical significance was tested by paired t test. (D) Mitochondrial mass was determined by measuring the mean fluorescence intensity (MFI) of mitochondria-specific dye mitotracker green (MTG) among CD8+ T lymphocytes. (D) Frequency of mitochondrial superoxide positive lymphocytes and level of mitochondrial superoxide (MFI) were determined by staining the CD8+ T lymphocytes with mitosox red dye. (F) Mitochondrial membrane depolarization was determined by the red to green ratio of MFIs of mitochondrial membrane potential-dependent dye JC-1 among the CD8+ T lymphocytes. Statistical significance was tested by Mann-Whitney test. *, P value< 0.05; **, P value< 0.01; ***, P value< 0.001; ns – not significant. PWH=People with HIV. HD= Healthy Donors. Figure 3.Lymphocyte changes, CD38 expression, and cytokine production in HIV-infected NSG mice.(A) Frequency of CD4+ and CD8+ T lymphocytes and comparison of ratio of the frequencies of CD4+ to CD8+ T cells between control and HIV infected humanized mice. Statistical significance determined by Mann-Whitney test. (B) Frequency of CD38+ and CD38+HLADR CD4+ (A) and CD8+ (B) T cells in HIV- infected humanized mice compared to control. Statistical significance determined by Mann-Whitney test. (D)Cytokine measurements of HIV-infected humanized mice and controls. Statistical significance was tested by independent t test. *, P value< 0.05; **, P value< 0.01; ns – not significant. HLADR= Human Leukocyte Antigen – DR isotype, IFN=Interferon, IP=Inducible Protein, MCP=Monocyte Chemoattractant Protein, TNF=Tumor Necrosis Factor, IL=Interleukin. Conclusion ART decreases CD38 expression on CD8+ T cells, but not to the levels of HIV-negative individuals. In vitro, T cells of PWH have altered mitochondrial function, and HIV-specific stimulation augments CD38 expression on CD8+ T cells and contributes to a proinflammatory response. These findings translate to a humanized mouse model, where HIV infection upregulates CD38 expression and cytokine production. Together, these data suggest that CD38 is a potential therapeutic target for mitigating the mitochondrial dysfunction and chronic inflammation that drive cellular aging and comorbidities in PWH. Disclosures Poonam Mathur, DO, MPH, American Academy of HIV Medicine: Honoraria|Med Learning Group: Speaker/presenter|NACCME: Advisor/Consultant|NKGP Pharma: Advisor/Consultant Shyam Kottilil, MD, PhD, Arbutus Pharmaceuticals: Grant/Research Support|Gilead: Grant/Research Support|Merck: Grant/Research Support|Regeneron Pharmaceuticals: Advisor/Consultant|Silverback Therapeutics: Advisor/Consultant|The Liver Company: Advisor/Consultant|Yufan Biotechnologies: Advisor/Consultant.