SLPI
Description
The SLPI (secretory leukocyte peptidase inhibitor) is a protein-coding gene located on chromosome 20.
SLPI, or secretory leukocyte protease inhibitor, is an enzyme encoded by the SLPI gene in humans. It is a highly cationic single-chain protein with eight intramolecular disulfide bonds. SLPI is abundant in bronchial, cervical, and nasal mucosa, saliva, and seminal fluids. It inhibits human leukocyte elastase, human cathepsin G, human trypsin, neutrophil elastase, and mast cell chymase. X-ray crystallography reveals that SLPI possesses two homologous domains of 53 and 54 amino acids. The C-terminal domain exhibits anti-protease activity, while the function of the N-terminal domain remains unknown. SLPI protects epithelial tissues from serine proteases and is found in various secretions, including seminal plasma, cervical mucus, and bronchial secretions. It exhibits affinity for trypsin, leukocyte elastase, and cathepsin G. Its inhibitory effect contributes to the immune response by shielding epithelial surfaces from endogenous proteolytic enzymes. Additionally, SLPI is believed to possess broad-spectrum antibiotic activity. The SLPI gene is expressed by cells at numerous mucosal surfaces located in the tissues of the lungs, cervix, seminal vesicles, and parotid ducts. SLPI is a dominant protein in nasal epithelial lining fluid and other nasal secretions.
SLPI is an acid-stable proteinase inhibitor with strong affinities for trypsin, chymotrypsin, elastase, and cathepsin G. It modulates inflammatory and immune responses following bacterial and Leishmania major infections. SLPI downregulates responses to bacterial lipopolysaccharide (LPS), plays a role in regulating NF-κB activation and inflammatory responses, and exhibits antimicrobial activity against mycobacteria but not against Salmonella. SLPI contributes to normal resistance against infection by Mycobacterium tuberculosis and Leishmania major. It is required for normal wound healing, likely by preventing tissue damage through limiting protease activity. In conjunction with ELANE, SLPI is essential for normal differentiation and proliferation of bone marrow myeloid cells.
SLPI is also known as ALK1, ALP, BLPI, HUSI, HUSI-I, MPI, WAP4, WFDC4.
Associated Diseases
- bacterial urinary tract infection
- autosomal dominant macrothrombocytopenia
- thrombocytopenia 7
- Glanzmann thrombasthenia 1
- recurrent Neisseria infections due to factor D deficiency
- bleeding disorder, platelet-type, 24
- platelet-type von Willebrand disease
- immunodeficiency 28
- bipolar disorder
