Abstract

HIV-infected adults are at an increased risk to lower respiratory tract infections (LRTIs). CD8+CD161++TCRvα7.2+ T cells are an innate-like T cell subset that are thought to play an important role in early defense against pathogens in the respiratory tract. HIV infection leads to irreversible depletion of these cells in peripheral blood, however, its impact on this subset in the human airway is still unclear. Here, we show presence of CD103 expressing CD8+CD161++TCRvα7.2+ T cells in the airway that exhibited a distinct cytokine functional profile compared to their CD103− airway counterparts and those from peripheral blood. These CD103 expressing airway CD8+CD161++TCRvα7.2+ T cells were selectively depleted in untreated HIV-infected adults compared to healthy controls. Their frequency was positively correlated with frequency of airway CD4+ T cells. Furthermore, the frequency of airway CD8+CD161++TCRvα7.2+ T cells was also inversely correlated with HIV plasma viral load, while suppressive antiretroviral therapy (ART) resulted in restoration of airway CD8+CD161++TCRvα7.2+ T cells. Our findings show that CD103 expressing airway CD8+CD161++TCRvα7.2+ T cells are functionally distinct and are preferentially depleted during untreated asymptomatic HIV infection. Depletion of CD103 expressing airway CD8+CD161++TCRvα7.2+ T cells, at a major portal of pathogen entry, could partly contribute to the increased propensity for opportunistic LRTIs observed in untreated HIV-infected adults.

Highlights

  • HIV-infected individuals are at an increased risk to lower respiratory tract infections (LRTIs) [1, 2], which account for 75–98% of lung complications in untreated HIV-infected adults worldwide [3, 4]

  • HIV is associated with a depletion of peripheral blood CD161++TCRvα7.2+ T cells [34, 35], we investigated whether asymptomatic HIV infection alters the frequency of airway CD8+CD161++TCRvα7.2+ T cells

  • There is limited data on the phenotypic and functional characteristics of human airway CD8+CD161++TCRvα7.2+ T cells and how HIV impacts these cells in asymptomatic individuals from high respiratory disease-burdened settings

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Summary

Introduction

HIV-infected individuals are at an increased risk to lower respiratory tract infections (LRTIs) [1, 2], which account for 75–98% of lung complications in untreated HIV-infected adults worldwide [3, 4] This susceptibility to LRTIs is largely attributed to HIV-induced disruption of lung immunity, including global alteration in airway immune cell homeostasis [5], reduced frequency of respiratory antigen-specific airway CD4+ T cells [6, 7], as well as, impaired alveolar macrophage function [6, 8]. CD161++TCRvα7.2+ T cells have characteristics of innate cells and a degree of sophistication possessed by adaptive lymphocytes They express a semi-invariant T cell receptor, which recognizes microbial vitamin B2 (riboflavin) metabolites (5(2-oxoethylideneamino)-6-D-ribitylaminouracil or 5-OP-RU), presented via major histocompatibility complex (MHC) class I-related (MR) 1 molecule [14,15,16,17]. These qualities highlight the importance of CD161++TCRvα7.2+ T cells in antimicrobial defense and preservation of mucosal barrier integrity

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