A Functional Variant of CXCL16 Is Associated with Predisposition to Sepsis and MODS in Trauma Patients

Abstract

Background: CXC chemokine famliy genes play an important role in inflammatory and immune diseases. CXCL16 affects the occurrence and development of inflammation through leukocyte chemotaxis, leukocyte adhesion and endotoxin clearance. In this study, we selected a set of tag SNPs in the CXCL16 gene and investigated their clinical relevance to the development of sepsis and multiple organ dysfunction syndrome (MODS) in patients with major trauma in three independent Chinese Han populations. Methods: A total of 1,620 major trauma patients were enrolled in this study. Among these patients, 920 came from Chongqing in western China, 350 came from Zhejiang Province in eastern China, and 350 came from Guizhou Province in southern China. The improved multiplex ligation detection reaction (iMLDR) method was employed in the genotyping and genetic association analyses to determine the associations between CXCL16 haplotypes and sepsis morbidity rate and higher MOD scores in three cohorts. Results: The CXCL16 T123V181 haplotype was determined to be associated with increased risk for sepsis morbidity and higher MOD scores in the three cohorts. In vitro chemotactic experiments demonstrated that the T123V181 protein enhanced the chemotaxis of immunocytes. The adhesion ability of THP-1 cells expressing T123V181 to immunocytes was also stronger than those of cells with the other three haplotypes. T123 and V181 altered the structure of the CXCL16 active center, which resulted in changes in protein function and changes in the adhesion and chemotaxis of CXCL16-expressing immunocytes. These structural changes might be responsible for the increased incidence of sepsis and the higher MODS scores. Conclusions: We demonstrate that genetic variations in the CXCL16 gene regulate the sepsis morbidity rate, and we explore a paradigm for the prewarning diagnosis of sepsis tailored to the genetic information of individual patients. Trial registration: ClinicalTrials.gov, NCT01713205. Registered 18 October 2012, retrospectively registered.