Antileukoproteinase

Also known as: BLPI, HUSI-1, Mucus proteinase inhibitor, Protease inhibitor WAP4, Secretory leukocyte protease inhibitor, Seminal proteinase inhibitor, WAP four-disulfide core domain protein 4, SLPI, P03973

Antileukoproteinase, also known as secretory leukocyte protease inhibitor (SLPI), is a 11.7 kDa serine protease inhibitor belonging to the WAP (whey acidic protein) four-disulfide core family. Its primary mechanism of action involves reversible, high-affinity inhibition of neutrophil-derived proteases such as elastase, cathepsin G, and trypsin, as well as chymotrypsin. The protein is acid-stable and secreted by mucosal epithelial cells, where it protects tissues from proteolytic damage during inflammation. Additionally, SLPI exhibits antimicrobial and anti-inflammatory properties, including inhibition of NF-κB activation and modulation of macrophage responses. Key research findings from 92 PubMed references indicate that SLPI plays a protective role in chronic inflammatory diseases, including cystic fibrosis, chronic obstructive pulmonary disease (COPD), and asthma, by neutralizing excessive protease activity. Studies also demonstrate its involvement in wound healing, where it promotes re-epithelialization, and in host defense against bacterial and viral infections, such as HIV-1 and influenza. Experimental models show that SLPI deficiency exacerbates inflammation and tissue damage, while exogenous administration reduces protease-mediated injury. Clinically, SLPI is being investigated as a potential therapeutic agent for inflammatory lung diseases, where aerosolized delivery could mitigate elastase-driven tissue destruction. Its dual anti-protease and anti-inflammatory actions make it a candidate for conditions with dysregulated protease activity. However, its experimental status limits current clinical application, and further research is needed to establish safety and efficacy in human trials. For research purposes only — not medical advice.

Key data

Mechanism of action

Acid-stable proteinase inhibitor with strong affinities for trypsin, chymotrypsin, elastase, and cathepsin G (PubMed:10702419, PubMed:2039600, PubMed:2110563, PubMed:24121345, PubMed:3462719, PubMed:3533531). Modulates the inflammatory and immune responses after bacterial infection, and after infection by the intracellular parasite L.major. Down-regulates responses to bacterial lipopolysaccharide (LPS) (By similarity). Plays a role in regulating the activation of NF-kappa-B and inflammatory responses (PubMed:10702419, PubMed:24352879). Has antimicrobial activity against mycobacteria, but not against salmonella. Contributes to normal resistance against infection by M.tuberculosis. Required for normal resistance to infection by L.major. Required for normal wound healing, probably by preventing tissue damage by limiting protease activity (By similarity). Together with ELANE, required for normal differentiation and proliferation of bone marrow myeloid cells (PubMed:24352879)

Research & studies

Frequently asked questions

Related peptides