Context-dependent roles of integrin CD11d in neutrophil responses during sepsis

Introduction/Background CD11d (integrin αDβ2) is primarily expressed by myeloid cells, but its role in neutrophil signaling and maturation during sepsis remains poorly defined. Methods We investigated the function of CD11d/Itgad using bulk RNA sequencing of blood and lung neutrophils from wild-type and CD11d-deficient mice at baseline and 12 h after cecal ligation and puncture (CLP), complemented by single-cell RNA-seq analyses of lung and bone marrow. Results We found that CD11d deficiency had minimal effects on blood neutrophils but substantially altered the lung neutrophil transcriptome, particularly programs governing maturation. At baseline, CD11d KO lung neutrophils showed an alarmin-associated transcriptional signature ( S100a8, S100a9, Il1b ), reduced expression of genes encoding components of integrin outside-in signaling ( Syk, Ptk2b, Rac2 ), and an elevated immature neutrophil score relative to WT. Strikingly, this phenotype reversed after CLP: KO neutrophils acquired a more mature transcriptional state than WT, despite reduced expression of granulopoiesis regulators ( Cebpa, Cebpb, Csf3 ) and attenuated NF-κB-dependent inflammatory and acute-phase programs. Deconvolution of independent lung single-cell data corroborated this maturation shift. Comparison with CD11c-deficient neutrophils revealed divergent maturation phenotypes despite shared interferon and NF-κB pathway changes, with CD11d loss favoring a Cd101-high mature state versus CD11c loss favoring a Cebpb -high immature state. Single cell analyses localized Itgad expression to a small Mki67+Top2a+ pre-neutrophil population in the lung and to neutrophil precursors in bone marrow, with expression declining progressively across maturation stages. Discussion Together, these findings associate CD11d deficiency with context-dependent changes in neutrophil maturation-associated transcriptional programs during sepsis, distinct from but partially overlapping with CD11c-dependent programs.