PLCB3 Loss-of-function Reduces P. aeruginosa-dependent IL-8 Release in Cystic Fibrosis

An excessive inflammation orchestrated by release of neutrophilic chemokine IL-8 from bronchial epithelial cells, amplified by Pseudomonas aeruginosa (P. aeruginosa) infection, is a hallmark of lung disease of Cystic Fibrosis (CF) patients. To identify novel anti-inflammatory molecular targets, we previously performed a genetic study of 135 genes of the immune response, which identified the c.2534C>T (p.S845L) variant of phospholipase C beta 3 (PLCB3) as being significantly associated with mild progression of pulmonary disease. Silencing PLCB3 revealed that it potentiates the Toll-like Receptor's inflammatory signaling cascade originating from CF bronchial epithelial cells. Here we investigated the role of PLCB3-S845L variant along with two synthetic mutants paradigmatic of impaired catalytic activity or lacking functional activation in CF bronchial epithelial cells. In experiments, where cells were exposed to P. aeruginosa, the Supernatant of Mucopurulent Material from the airways of CF patients or different agonists, show that PLCB3-S845L has defects of: a. agonist-induced Ca2+ release from endoplasmic reticulum and rise of cytosolic [Ca2+]; b. activation of conventional Protein Kinase C isoform β; c. induction of IL-8 release. These results, besides identifying S845L as a loss-of-function variant, strongly consolidate PLCB3 as a relevant molecular target capable to attenuate the excessive recruitment of neutrophils without completely abolishing the inflammatory response in CF lung disease.