{"doi":"10.1093/jleuko/qiaf091","title":"Alpha-1 antitrypsin modulates neutrophil phenotype and function: implications for inflammatory regulation","abstract":"Alpha-1 antitrypsin, the most abundant protease inhibitor within the plasma, plays a crucial role in regulating neutrophils' function during inflammation. Alpha-1 antitrypsin deficiency is associated with excessive neutrophilic inflammation, yet the mechanisms underlying alpha-1 antitrypsin's role in neutrophil trafficking remain poorly understood. Here, we demonstrate alpha-1 antitrypsin is essential for maintaining neutrophil polarity, directional migration, and tissue infiltration during inflammation. Using alpha-1 antitrypsin-knockout mice, we found these mice present increased numbers of neutrophils in the bone marrow, impaired mobilization, and reduced liver neutrophil infiltration following lipopolysaccharide-induced systemic inflammation. Flow cytometry and immunohistochemistry revealed alpha-1 antitrypsin-knockout neutrophils had lower CD44 expression and defective F-actin polarization leading to impaired chemotaxis. Importantly, low expression of CD44 prevented efficient adhesion and transmigration of alpha-1 antitrypsin-knockout neutrophils across liver sinusoidal endothelial cells. Furthermore, chemotaxis assays showed alpha-1 antitrypsin-knockout neutrophils in alpha-1 antitrypsin-deficient media displayed random motility and loss of directional migration toward fMLP (N-Formyl-Met-Leu-Phe), suggesting a critical role for alpha-1 antitrypsin in neutrophil trafficking. Additionally, plasma alpha-1 antitrypsin deficiency delayed neutrophils' rate of phagocytosis. Mechanistically, alpha-1 antitrypsin deficiency resulted in excessive ERK1/2 (Extracellular Signal-Regulated Kinase 1/2) activation in alpha-1 antitrypsin-knockout neutrophils, driving an interleukin-10-enriched environment while suppressing expression of CXCL1 (C-X-C Motif Chemokine Ligand 1) and CXCL10 (C-X-C Motif Chemokine Ligand 10), chemokines essential for neutrophil recruitment. Notably, exposure to wild-type plasma with sufficient alpha-1 antitrypsin restored ERK1/2 activation, CD44 expression, and chemokine levels in alpha-1 antitrypsin-knockout neutrophils, confirming the role of circulating alpha-1 antitrypsin in maintaining neutrophil function. These findings highlight alpha-1 antitrypsin as a key regulator of neutrophil trafficking, adhesion, and immune signaling, with implications for alpha-1 antitrypsin deficiency-related inflammatory disorders.","journal":"Journal of Leukocyte Biology","year":2025,"id":521537,"datarank":0.0,"base_score":0.0,"endowment":0.0,"self_citation_contribution":0.0,"citation_network_contribution":0.0,"self_endowment_contribution":0.0,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":5,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9509,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2025-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":406869,"name":"Ishan Patel","orcid":"0000-0002-1100-4619","position":1,"is_corresponding":false},{"id":1392383,"name":"Laith Khartabil","orcid":null,"position":2,"is_corresponding":false},{"id":366238,"name":"Divya S. Katikaneni","orcid":"0000-0001-7562-3892","position":3,"is_corresponding":false},{"id":442385,"name":"Yogesh Scindia","orcid":"0000-0001-6382-6289","position":4,"is_corresponding":false},{"id":316824,"name":"Nazli Khodayari","orcid":"0000-0002-4659-1622","position":5,"is_corresponding":false},{"id":318931,"name":"Regina Oshins","orcid":null,"position":0,"is_corresponding":true}],"reference_count":45,"raw_metadata":null,"created_at":"2026-07-19T02:49:44.558743Z","pmid":"40590483","pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}