Antiretroviral therapy (ART) is the standard of care for patients with HIV. For most patients, ART-mediate suppression of HIV replication is accompanied by reconstitution of CD4+ T cells; however, in some cases, the CD4+ T cell population is not fully restored, and these immunological nonresponders (INRs) have increased mortality. In this episode, Irini Sereti, Andrea Lisco, and colleagues identify and characterize immune parameters of 5 patients with a dramatic decline of CD4+ T cells despite ART-mediated viral suppression that is greater than that of subjects with INR. The authors define this condition as extreme immune decline (EXID) and show that it can result from the development of anti–CD4+ T cell autoantibodies and aberrant inflammasome/caspase-1 activation.
BACKGROUND. The goal of antiretroviral therapy (ART) is to suppress HIV-1 replication and reconstitute CD4+ T cells. Here, we report on HIV-infected individuals who had a paradoxical decline in CD4+ T cells despite ART-mediated suppression of plasma HIV-1 load (pVL). We defined such an immunological outcome as extreme immune decline (EXID). METHODS. EXID’s clinical and immunological characteristics were compared to immunological responders (IRs), immunological nonresponders (INRs), healthy controls (HCs), and idiopathic CD4+ lymphopenia (ICL) patients. T cell immunophenotyping and assembly/activation of inflammasomes were evaluated by flow cytometry. PBMC transcriptome analysis and genetic screening for pathogenic variants were performed. Levels of cytokines/chemokines were measured by electrochemiluminescence. Luciferase immunoprecipitation system and NK-mediated antibody-dependent cellular cytotoxicity (ADCC) assays were used to identify anti-lymphocyte autoantibodies. RESULTS. EXIDs were infected with non-B HIV-1 subtypes and after 192 weeks of consistent ART-mediated pVL suppression had a median CD4+ decrease of 157 cells/μl, compared with CD4+ increases of 193 cells/μl and 427 cells/μl in INR and IR, respectively. EXID had reduced naive CD4+ T cells, but similar proportions of cycling CD4+ T cells and HLA-DR+CD38+CD8+ T cells compared with IR and INR. Levels of inflammatory cytokines were also similar in EXID and INR, but the IL-7 axis was profoundly perturbed compared with HC, IR, INR, and ICL. Genes involved in T cell and monocyte/macrophage function, autophagy, and cell migration were differentially expressed in EXID. Two of the 5 EXIDs had autoantibodies causing ADCC, while 2 different EXIDs had an increased inflammasome/caspase-1 activation despite consistently ART-suppressed pVL. CONCLUSIONS. EXID is a distinct immunological outcome compared with previously described INR. Anti–CD4+ T cell autoantibodies and aberrant inflammasome/caspase-1 activation despite suppressed HIV-1 viremia are among the mechanisms responsible for EXID.
Andrea Lisco, Chun-Shu Wong, Silvia Lucena Lage, Itzchak Levy, Jason Brophy, Jeffrey Lennox, Maura Manion, Megan V. Anderson, Yolanda Mejia, Christopher Grivas, Harry Mystakelis, Peter D. Burbelo, Ainhoa Perez-Diez, Adam Rupert, Craig A. Martens, Sarah L. Anzick, Caryn Morse, Shanna Chan, Claire Deleage, Irini Sereti