Serum S100A8 As An Early Diagnostic Biomarker In Patients With Community Acquired Pneumonia

Background Community acquired pneumonia（CAP）is one of the high morbidity and mortality of lung infectious diseases.Early detection,diagnosis and treatment of CAP are beneficial to patient outcome and financial burden,so it is necessary to find a biomarker for diagnosis,prediction of severity and determination of methods to reduce the incidence or severity.Limited studies have suggested that calprotectin may take part in the pathophysiology of community-acquired pneumonia（CAP）.Nevertheless,there is no clinical study analysing the role of S100A8 in CAP patients.Objective The objective of this study was to analyse the association of serum S100A8 with the severity of CAP and determine the cut-off values of S100A8 for predictive power based on a cross-sectional study.Methods A total of 200 CAP patients and 100 normal subjects were recruited.Demographic data,clinical information,and serum were collected on admission.S100A8 and inflammatory cytokines were detected using enzyme linked immunosorbent assay（ELISA）and reverse transcription-polymerase chain reaction（RT-PCR）.All statistical analyses were performed with SPSS 19.0.Results Serum S100A8 was increased in CAP patients on admission.Serum S100A8 was gradually increased in parallel with CAP severity scores.Serum S100A8 was positively correlated with CAP severity scores,blood routine parameters,and inflammatory cytokines.Furthermore,univariate and multivariate logistical regression revealed that there were positive associations between serum S100A8 with CRB-65,PSI,and CURXO.Moreover,the predictive capacity of serum S100A8 was determined by ROC curve analysis.The area under the curves of S100A8 for CAP and CAP severity were 0.855 and 0.893,respectively.Mechanistic analysis found that S100A8 knockdown alleviated streptococcus pneumoniae-evoked inflammatory cytokines in A549 cells.Conclusion Serum S100A8 on admission was positively associated with the severity of CAP.S100A8 knockdown alleviates streptococcus pneumoniae-evoked inflammatory cytokines in A549 cells,indicating that S100A8 may exert a significant effect on the pathophysiology of CAP and could be an early serum diagnostic biomarker for CAP.