Pcyox1l controls neutrophil maturation and functionality

Little is known about how commensal colonization controls neutrophil differentiation and functions. Using system immunology approaches we discovered commensal and infection induced changes in neutrophil proteomes. The identified differentially expressed genes were CRISPRed out in immortalized neutrophil progenitor cell lines transduced with lenti-guides. Analysis of maturation and bactericidal capacity of the generated CRISPRed clones ascribed a function to a currently unknown protein-termed Prenylcysteine oxidase 1 like (Pcyox1l). Pcyox1l deficient neutrophils show dramatic defects in longevity, autophagy, and bactericidal functions associated with reductions in SerpinB1a transcripts and protein. Metabolic labeling experiments revealed that Pcyox1l controls levels of protein prenylation, highlighting its key enzymatic function. The Pcyox1l deficiency phenotype is phenocopied by SerpinB1a deficiency in neutrophils signifying linked mechanisms. Commensal colonization increases Pcyox1l and SerpinB1a levels in polymorphonuclear leukocytes (PMNs) in specific pathogen free (SPF) mice when compared to germ free (GF) mice and, conversely, Pcyox1l KO mice demonstrated altered commensal microbiome and elevated susceptibility to bacterial infection. Cumulatively, our data highlight a novel metabolic pathway which is controlled by commensal colonization and governs neutrophil functionality, longevity, and bactericidal properties. In lieu with the impairment of neutrophil bactericidal functions, Pcyox1l KO mice showed elevated susceptibility to infection with the Gram-negative pathogen Pseudomonas aeruginosa