CCR1 silencing in macrophage-like cells reduces alveolar epithelial cell death and junctional protein loss

Background Macrophage activation accompanies epithelial injury in acute inflammatory lung disease, but the receptors linking inflammatory signaling to epithelial cell death remain incompletely characterized. Methods We analyzed five public transcriptomic cohorts comprising 158 clinical profiles, including bronchoalveolar lavage fluid (BALF) and peripheral-blood single-cell datasets and three whole-blood cohorts. Cell composition, cell-death and stress programs, pseudobulk expression, pathway enrichment, and sample-specific cell-cell communication were integrated to nominate a receptor for perturbation. CCR1 was silenced in LPS/ATP-stimulated THP-1-derived macrophage-like cells, and their conditioned medium was applied to primary human pulmonary alveolar epithelial cells. Results The BALF atlas contained 86,315 cells. Increasing disease severity was accompanied by higher neutrophil, injury-transitional epithelial, and interferon-state macrophage fractions. Epithelial autophagy, necroptosis, and hypoxia/glycolysis scores increased with severity, whereas the autophagy score was the principal severity-associated macrophage program. Three retained chemokine interactions converged on CCR1, supported by receptor expression, pseudobulk analysis, and its association with macrophage autophagy. Whole-blood module effects varied across cohorts. CCR1 silencing reduced macrophage inflammatory transcripts and IL-1β and TNF -α release. Conditioned medium from CCR1 -silenced macrophage-like cells reduced epithelial Annexin V positivity from 39.0% ± 1.73% to 16.9% ± 1.69%, lowered LDH release, and preserved junction-related transcripts and proteins. Conclusion Transcriptomic analyses and cellular perturbation support a contribution of macrophage CCR1 to inflammatory activation, epithelial cell death, and junctional injury in the tested acute lung-injury model.