title: Functional characterization of polymorphisms in the peptidase inhibitor 3 (elafin) gene and validation of their contribution to risk of acute respiratory distress syndrome.
abstract: Elafin (peptidase inhibitor 3 [PI3]) and its biologically active precursor, pre-elafin, are neutrophil serine proteinase inhibitors with an important role in preventing excessive tissue injury during inflammatory events. Recently, we reported an association between single-nucleotide polymorphism (SNP) rs2664581 in the PI3 gene, increased risk of acute respiratory distress syndrome (ARDS) and pre-elafin circulating levels. This study aims to validate the legitimacy of this association by using a cohort of patients who met the criteria for systemic inflammatory response syndrome and were at risk of developing ARDS (n = 840). A comprehensive functional study of SNPs in PI3 gene was also performed. Luciferase assays and electrophoretic mobility shift assays were conducted to determine the functional relevance of promoter region variants. The effect of the coding SNP rs2664581 on the neutrophil elastase inhibitory activity and transglutaminase binding properties of pre-elafin was also investigated. The variant allele of rs2664581 (C) was significantly associated with increased ARDS risk, mainly among subjects with sepsis (odds ratio = 1.44; 95% confidence interval = 1.04-1.99; P = 0.0276, adjusted by age, sex, and Acute Physiology and Chronic Health Evaluation III). Pre-elafin recombinant protein carrying the amino acid change associated with rs2664581 (Thr34Pro, mutant protein [MT]) had greater capacity to undergo transglutaminase-mediated cross-linking to immobilized fibronectin than wild-type protein in vitro (P < 0.003). No differences were observed in the neutrophil elastase inhibitory activities of wild-type versus MT proteins. In addition, the risk allele-promoter construct had significantly lower cytokine-induced transcriptional activity. Electrophoretic mobility shift assay results indicated a differential binding of nuclear proteins to the G and A alleles of SNP -338G > A. Our results confirm the association between SNP rs2664581 and enhanced risk of ARDS, further supporting the role of PI3 in ARDS development. SNPs in the PI3 locus may act synergistically by regulating PI3 gene expression and pre-elafin biological functions.
authors.affiliation: 1 Harvard School of Public Health, Boston, Massachusetts.
authors.forename: Paula
authors.initials: P
authors.lastname: Tejera
authors.forename: D Shane
authors.initials: DS
authors.lastname: O'Mahony
authors.forename: Caroline A
authors.initials: CA
authors.lastname: Owen
authors.forename: Yongyue
authors.initials: Y
authors.lastname: Wei
authors.forename: Zhaoxi
authors.initials: Z
authors.lastname: Wang
authors.forename: Kushagra
authors.initials: K
authors.lastname: Gupta
authors.forename: Li
authors.initials: L
authors.lastname: Su
authors.forename: Jesus
authors.initials: J
authors.lastname: Villar
authors.forename: Mark
authors.initials: M
authors.lastname: Wurfel
authors.forename: David C
authors.initials: DC
authors.lastname: Christiani
mesh_terms: D000328:Adult; D000368:Aged; D001665:Binding Sites; D016022:Case-Control Studies; D045744:Cell Line, Tumor; D016207:Cytokines / Q000378:metabolism; D053492:Elafin / Q000235:genetics* / Q000378:metabolism; D005260:Female; D005353:Fibronectins / Q000378:metabolism; D005786:Gene Expression Regulation; D005787:Gene Frequency; D017930:Genes, Reporter; D056726:Genetic Association Studies; D020022:Genetic Predisposition to Disease; D006239:Haplotypes; D006801:Humans; D019272:Leukocyte Elastase / Q000378:metabolism; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D016017:Odds Ratio; D010641:Phenotype; D020641:Polymorphism, Single Nucleotide; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D012128:Respiratory Distress Syndrome / Q000235:genetics* / Q000378:metabolism; D012307:Risk Factors; D018746:Systemic Inflammatory Response Syndrome / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic; D014162:Transfection; D011503:Transglutaminases / Q000378:metabolism
chemical_list: D016207:Cytokines; D053492:Elafin; D005353:Fibronectins; C506806:PI3 protein, human; D011503:Transglutaminases; D019272:Leukocyte Elastase
keywords: acute respiratory distress syndrome; elafin; genetic association; replication; single-nucleotide polymorphism