Smoking and Human Immunodeficiency Virus 1 Infection Promote Retention of CD8⁺ T Cells in the Airway Mucosa

Smoking and human immunodeficiency virus 1 (HIV-1) infection are risk factors for chronic obstructive pulmonary disease (COPD), which is among the most common comorbid conditions in people living with HIV-1. HIV-1 infection leads to persistent expansion of CD8⁺ T cells, and CD8⁺ T cell-mediated inflammation has been implicated in COPD pathogenesis. In this study, we investigated the effects of HIV-1 infection and smoking on T-cell dynamics in patients at risk of COPD. BAL fluid, endobronchial brushings, and blood from HIV-1 infected and uninfected nonsmokers and smokers were analyzed by flow cytometry, and lungs were imaged by computed tomography. Chemokines were measured in BAL fluid, and CD8⁺ T-cell chemotaxis in the presence of cigarette smoke extract was assessed in vitro. HIV-1 infection increased CD8⁺ T cells in the BAL fluid, but this increase was abrogated by smoking. Smokers had reduced BAL fluid concentrations of the T cell-recruiting chemokines CXCL10 and CCL5, and cigarette smoke extract inhibited CXCL10 and CCL5 production by macrophages and CD8⁺ T-cell transmigration in vitro. In contrast to the T cells in BAL fluid, CD8⁺ T cells in endobronchial brushings were increased in HIV-1-infected smokers, which was driven by an accumulation of effector memory T cells in the airway mucosa and an increase in tissue-resident memory T cells. Mucosal CD8⁺ T-cell numbers inversely correlated with lung aeration, suggesting an association with inflammation and remodeling. HIV-1 infection and smoking lead to retention of CD8⁺ T cells within the airway mucosa.