Secretory leukocyte protease inhibitor (SLPI) (SLPI)

Secretory leukocyte protease inhibitor (SLPI), also known as mucus proteinase inhibitor, is a 12 kDa non-glycosylated protein that plays a critical role in innate immunity and tissue protection [1, 3]. It is primarily produced by epithelial cells and myeloid cells and is found at high concentrations in mucosal fluids such as bronchial secretions, saliva, and cervical mucus [1, 6]. SLPI's primary biological function is the potent inhibition of serine proteases, most notably neutrophil elastase, which prevents excessive tissue degradation during inflammatory responses [2, 4]. Additionally, SLPI exerts anti-inflammatory effects by suppressing the activation of the NF-kappaB transcription factor and demonstrates direct antimicrobial activity against a variety of pathogens, including HIV-1 and various bacteria [3, 7]. In clinical contexts, a deficiency or inactivation of SLPI is associated with chronic inflammatory lung diseases like cystic fibrosis and emphysema, making it a significant therapeutic target for protease-replacement therapies [2, 18].

Other names

Mucus proteinase inhibitorAntileukoproteaseBronchial secretory inhibitorHuman seminal inhibitor ICervix uteri secretion inhibitorMPIALPWAP4

Inhibition of neutrophil elastase and other serine proteases to restore protease-antiprotease balance; suppression of NF-kappaB-mediated inflammatory signaling.