Proteomic Study On Disease Severity And Prognosis Of Childhood Asthma

Background: Bronchial asthma is a common disease in children, due to multiplefactors, the incidence of the disease grow higher than ever. Childhood asthma has a naturalhistory different from that of adult asthma. Symptoms of2/3asthma children will disappearwhen they reach adult age, while another1/3will continue and finally develop adult asthma.This phenomenon implies that there must be some underlying mechanisms in it; Besidesthat, Clinically we evaluate asthma disease severity and control condition by clinicalmanifestations and lung function tests, but most of their lung function tests show normalwhile the bronchial inflammations are still there or progressing. Evaluating the severity andprognosis of childhood asthma is important to the clinical management of the disease andunderstanding the pathogenesis of it, also help to relieve the parents’ anxiety about thefuture of their children’s disease. Currently we lack reliable tests that are sensitive andobjective in evaluating childhood asthma, and prospective studies in this field are needed.Disease related biomarkers can help to diagnose and evaluate diseases objectively. Proteomicmethods can help to find series of disease related biomarkers, even to find novel biomarkerswhich never be connected with the disease.Objective: We want to use proteomic methods to find childhood asthma relatedbiomarkers.Methods: Two dimensional differential gel electrophoresis techniques (2D–DIGE)were used upon plasma samples of stable asthmatic children (intermittent, mild persist,moderate persist, severe persist, subgrouped according to GINA) and healthy controls toseparate and screen for differential expression of proteins. The candidate proteins wereidentified by Matrix-Assisted Laser Desorption/Ionization Time of Flight MassSpectrometry (MALDI TOF/TOF MS). Then were validated by ELISA in another largerpediatric population to evaluate candidate protein markers associated with disease severity; These candidate markers then have been further validated by ELISA in a large population. Inthis longitudinal cohort study we conducted a3years follow up trial with various groups inview of clarifying the disease association with childhood asthma prognosis.Results: By comparing protein levels in the plasma samples of asthmatic and healthycontrols using proteomic techniques,36protein markers were found differentially expressed(p<0.05) between4asthmatic and healthy control groups,20proteins were identified byMass Spectrometry which represent set of8proteins. Further validation of these proteins in aseparate large clinical group was preformed. We found that a panel of four biomarkers(antithrombin–III (AT–III), alpha2-macroglobulin(A2M), CD5antigen-like(CD5L), Com-plement3(C3)) consistently showed significantly differential expressions between differentasthmatic groups and healthy control group. AT-III, C3, A2M were differentially expressedbetween asthmatic and healthy control group (p<0.05); among the different asthmaticgroups, A-TIII expressions showed a trend of gradually raising up with asthmatic diseaseseverity (ANOVA p<0.05), A2M and CD5L expressions showed reversed trends with thedisease severity (ANOVA,p<0.05, p<0.01). it was demonstrated that AT-III had a negativecorrelations with A2M (r=-0.259, p<0.05), CD5L(r=-0.276，p<0.05), and FEV1%/FVC%(r=-0.362, p<0.05), respectively; similarly, CD5L had a positive correlations with A2M(r=0.303, p<0.01) and FEV1%/FVC%(r=0.264，p<0.05), respectively. Among differentprognostic groups, A-TIII expressions showed a trend of raising up with asthmaticprognostic severity, CD5L showed reversed trend with asthmatic prognostic severity. A2Mand C3showed no obvious trend with asthmatic prognostic severity.Conclusions: Our study demonstrated that proteomics is a useful method in identifyasthma related novel biomarkers. The result showed that a panel of four biomarkers (CD5L,AT-III, A2M, and C3) seems to relate closely with childhood asthma disease severity andprognosis. The combination of the biomarkers can be a powerful tool in evaluating andmonitoring childhood asthma progress. The biomarkers may also underpin the diseasemechanism which warrant further exploration in understanding asthma pathogenesis.Now we lack specific indexes to evaluate childhood asthma, plasma biomarkers are a goodchoice to reflect the disease condition of childhood asthma, especially for the childhood population who are difficult to go through invasive examinations.