SLPI and inflammatory lung disease in females.
During the course of certain inflammatory lung diseases, SLPI (secretory leucoprotease inhibitor) plays a number of important roles. As a serine antiprotease it functions to protect the airways from proteolytic damage due to neutrophil and other immune cell-derived serine proteases. With respect to infection it has known antimicrobial and anti-viral properties that are likely to contribute to host defence. Another of its properties is the ability to control inflammation within the lung where it can interfere with the transcriptional induction of pro-inflammatory gene expression induced by NF-κB (nuclear factor κB). Thus, factors that regulate the expression of SLPI in the airways can impact on disease severity and outcome. Gender represents once such idiosyncratic factor. In females with CF (cystic fibrosis), it is now thought that circulating oestrogen contributes, in part, to the observed gender gap whereby females have worse disease and poorer prognosis than males. Conversely, in asthma, sufferers who are females have more frequent exacerbations at times of low-circulating oestrogen. In the present paper, we discuss how SLPI participates in these events and speculate on whether regulatory mechanisms such as post-transcriptional modulation by miRNAs (microRNAs) are important in the control of SLPI expression in inflammatory lung disease.