Structured Summary: HIV Suppression Restores the Lung Mucosal CD4⁺ T-Cell Viral Immune Response and Resolves CD8⁺ T-Cell Alveolitis in Patients at Risk for HIV-Associated Chronic Obstructive Pulmonary Disease–IntroductionHuman immunodeficiency virus (HIV) infection affects both systemic and mucosal immune systems, including the lungs. The pulmonary immune environment plays a crucial role in protecting against respiratory pathogens and maintaining normal lung function. However, HIV infection disrupts this balance by depleting CD4⁺ T cells and promoting chronic immune activation. One of the characteristic features observed in the lungs of HIV-infected individuals is CD8⁺ T-cell alveolitis, a condition characterized by an excessive accumulation of CD8⁺ T lymphocytes within the alveolar spaces.This persistent inflammatory response contributes to tissue damage and has been associated with an increased risk of developing HIV-associated chronic obstructive pulmonary disease (COPD), particularly among individuals who smoke. Although antiretroviral therapy (ART) effectively suppresses viral replication and improves systemic immunity, its effects on the lung mucosal immune system have been less clearly understood. The study aimed to investigate whether viral suppression through ART can restore lung mucosal CD4⁺ T-cell immune responses and reduce CD8⁺ T-cell–mediated inflammation in individuals at risk for HIV-associated COPD.–MethodsThe study evaluated HIV-infected individuals who were at increased risk for pulmonary disease, including many who had a history of cigarette smoking. Researchers collected immune samples from both the peripheral blood and the lungs using bronchoalveolar lavage (BAL), a procedure that allows analysis of immune cells within the alveolar spaces.Participants were examined before and after achieving viral suppression through antiretroviral therapy. The researchers analyzed the number, phenotype, and function of lung mucosal T cells, focusing on both CD4⁺ and CD8⁺ T-cell populations. Functional immune responses were evaluated by measuring the ability of T cells to produce antiviral cytokines such as interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α), and interleukin-2 (IL-2) when stimulated with HIV antigens.In addition, the study assessed markers associated with immune activation, apoptosis, and exhaustion, including Fas and programmed death-1 (PD-1). These markers helped determine whether viral suppression improved the survival and functional capacity of lung mucosal T cells.–ResultsThe results demonstrated that suppression of HIV replication through antiretroviral therapy significantly improved the immune environment within the lungs.First, viral suppression led to a restoration of lung mucosal CD4⁺ T-cell responses. After effective ART, the number of functional CD4⁺ T cells increased, and these cells showed enhanced antiviral activity. Specifically, CD4⁺ T cells produced higher levels of cytokines such as IFN-γ, TNF-α, and IL-2 in response to HIV antigens, indicating improved immune responsiveness.Second, the study found an improvement in the CD4⁺/CD8⁺ T-cell ratio within lung tissues. During uncontrolled HIV infection, the ratio is typically skewed toward CD8⁺ T cells due to severe depletion of CD4⁺ cells. After viral suppression, this imbalance was partially corrected, reflecting a more normalized immune environment.Third, researchers observed a resolution of CD8⁺ T-cell alveolitis in most participants. The excessive accumulation of CD8⁺ T cells in the alveoli declined significantly following viral suppression, suggesting that ART reduces the chronic inflammatory processes associated with HIV infection in the lungs.Finally, the study showed reduced expression of apoptosis and exhaustion markers, including Fas and PD-1, on lung mucosal CD4⁺ T cells. This finding indicates that viral suppression improves the survival and functionality of these immune cells, allowing them to participate more effectively in antiviral immune responses.–DiscussionThe findings of this study demonstrate that effective suppression of HIV replication through antiretroviral therapy not only restores systemic immunity but also significantly improves the immune environment of the lungs. Restoration of lung mucosal CD4⁺ T-cell function is particularly important because these cells play a central role in coordinating antiviral responses and maintaining mucosal immune defense.The resolution of CD8⁺ T-cell alveolitis suggests that much of the pulmonary inflammation observed in untreated HIV infection is driven by ongoing viral replication and immune activation. By suppressing the virus, ART reduces this chronic inflammatory stimulus, allowing immune cell populations within the lungs to return toward a more balanced state.These findings have important clinical implications for the prevention of HIV-associated COPD. Chronic inflammation and immune dysregulation in the lungs may contribute to airway damage and progressive decline in lung function. By restoring immune balance and reducing inflammation, early and sustained ART may help protect lung health and reduce the risk of long-term respiratory complications in individuals living with HIV.In conclusion, the study highlights the critical role of viral suppression in restoring pulmonary immune function. Antiretroviral therapy not only improves systemic immune responses but also reestablishes effective mucosal CD4⁺ T-cell immunity and resolves inflammatory CD8⁺ T-cell alveolitis in the lungs. These findings emphasize the importance of early HIV treatment in preventing chronic pulmonary disease and maintaining overall respiratory health.