Abstract: Objective To elucidate the molecular mechanisms by which Sema7a promotes inflammatory regression in acute pneumonia. Methods We investigated the role of soluble Sema7a in regulating macrophage metabolic reprogramming, promoting M2 polarization, accelerating inflammation resolution, and facilitating pulmonary homeostasis in a mouse model of acute pneumonia by employing Sema7a-eKO knockout mice, HE staining, ELISA, and advanced proteomic analyses. Results Both Sema7a-/- and Sema7a+/+ pneumonia models exhibited different degrees of destruction of alveolar structures in both groups at 24, 48, 72, and 96 h. Notably, Sema7a-/- mice displayed exacerbated more neutrophil/erythrocyte infiltration and more severe alveolar destruction compared to Sema7a+/+ mice. Sema7a-/- mice demonstrated prolonged resolution intervals (26.2 h vs. 13.8 h, P<0.05) and significantly elevated IL-6, KC, TNF-α, and IL-1β levels in bronchoalveolar lavage fluid at 48 h (P<0.05). 5D Label-free proteomic analysis revealed 101 320 peptide fragments and 7 357 protein alterations in Sema7a-treated macrophages. 59 proteins were associated with cellular processes, 52 with biological regulation, and 37 with metabolic processes (all P<0.05). Mitochondrial respiratory chain signaling showed significant modulation. Sema7a downregulated M1 markers (STAT-1, CD40, CD80) and pro-inflammatory cytokines while upregulating M2 markers (Arg1, CD163, CD206) and IL-10 at the protein level. Conclusion In an acute pneumonia model, soluble Sema7a protein can enhance mitochondrial oxidative phosphorylation through macrophage metabolic reprogramming, which drives M2 polarization, accelerates inflammatory cell clearance, and ultimately restores pulmonary homeostasis.

Key words: Acute pneumonia, Sema7a, Macrophages, Proteomics, Cytokine