What question did this study set out to answer?

The central aim is to analyze monocyte activation profiles and their association with endothelial and pulmonary functions in veterans with respiratory symptoms post-deployment.

February 12, 2026Open Access

Monocyte clusters suggestive of a chronic inflammatory phenotype are associated with reduced endothelial function in Veterans with respiratory symptoms

Key Points

The central aim is to analyze monocyte activation profiles and their association with endothelial and pulmonary functions in veterans with respiratory symptoms post-deployment.
Cross-sectional study design involving previously deployed veterans
Assessment of circulating monocyte immunophenotypes using clustering analysis
Evaluation of pulmonary function and brachial artery flow-mediated dilation (FMD)
Statistical analysis with principal component and hierarchical clustering techniques
Identification of two monocyte activation clusters: Cluster 1 and Cluster 2
Veterans in Cluster 2 showed impaired endothelial function measured by flow-mediated dilation (FMD/NMD ratio; p = 0.02)
Cluster 2 veterans also exhibited elevated airway resistance (R5; p = 0.01) despite normal pulmonary function
Findings suggest a link between monocyte profiles and vascular/airway dysfunction due to prolonged inflammation from deployment exposure

Abstract

Exposure to airborne hazards during deployment is associated with persistent respiratory symptoms among military veterans even years after deployment. Circulating monocytes, key components of the innate immune response, are implicated in inflammatory processes that may be sustained long after such exposures and contribute to related health issues. This cross-sectional study, conducted years after deployment, aimed to characterize monocyte activation profiles in veterans with deployment-related respiratory symptoms and investigate associations with physiological markers of pulmonary and vascular function. Circulating monocyte immunophenotype, pulmonary function, and brachial artery flow-mediated dilation (FMD) were assessed in 82 previously deployed veterans. Using principal component and hierarchical clustering analyses, we identified two distinct monocyte activation phenotypes: Cluster 1, characterized by elevated CD87, CD11b, and CD163, and cluster 2 which expressed markers of non-classical monocytes and CD195, indicative of a chronic inflammatory phenotype. Veterans in cluster 2 exhibited impaired endothelial-dependent vasodilation (FMD/NMD ratio; p = 0.02) and elevated airway resistance (R5; p = 0.01), despite normal pulmonary function. These findings suggest an association between distinct monocyte activation profiles and measures of microvascular and airway dysfunction in this cohort, potentially reflecting sustained inflammation secondary to environmental exposure. These observed associations underscore the need for further research into the role of monocytes in these long-term physiological changes. Elucidating the mechanistic pathways by which these monocyte phenotypes may contribute to persistent physiological alterations is critical and could inform future strategies for identifying at-risk veterans or exploring novel immunomodulatory approaches if such links are further substantiated.

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