A Study On The Association Between Asthma Phenotype And The Sensitivity Of Neutrophils To Glucocorticoid And The Level Of Plasma CC10

Part 1 Impaired anti-inflammatory action of glucocorticoid in neutrophil from patients with steroid-resistant asthmaObjective:The present study seeks to determine whether dexamethasone(DEX)has different effect on neutrophils from steroid sensitive(SS)asthmatics compared to steroid resistant(SR)asthmatics.Methods:Adults with asthma(n = 38)were classified as SR or SS based on changes in lung FEV1%following a one-month inhaled corticosteroid(ICS)treatment.Blood samples were collected from all patients during their first visit of the study.Neutrophils isolated from the blood were cultured with dexamethasone and/or atopic asthmatic serum for 18 h.The mRNA expression of mitogen-activated protein kinase phosphatase-1(MKP-1),a glucocorticoid transactivation target,and glucocorticoid-induced transcript 1(GLCCI1),an early marker of glucocorticoid-induced apoptosis whose expression was associated with the response to inhaled glucocorticoids in asthma,was determined by real-time PCR,and ELISA was used to assess the pro-inflammatory cytokine IL-8 levels in the supernatant.Constitutive neutrophil apoptosis was detected by flow cytometry.Results:DEX significantly induced MKP-1 expression in both patients with SS and SR patients in a concentration dependent manner,but greater induction was observed for SS patients at a low concentration(10 6 M).Asthmatic serum alone showed no MKP-1 expression,and there was impaired induction of MKP-1 by DEX in SR asthma patients at the present of asthmatic serum.The expression of GLCCI1 was not induced in neutrophils with DEX or DEX/atopic asthmatic serum combination.Greater inhibition of IL-8 production was observed in neutrophils from patients with SS asthma treated with DEX/atopic asthmatic serum combination compared with SR asthma patients,though DEX alone showed the same effect on neutrophils from SS and SR asthma patients.Meanwhile,DEX dependent inhibition of constitutive neutrophil apoptosis was similar between SS asthma and SR asthma patients.Conclusions:The impaired induction of MKP-1 and inhibition of IL-8 production by DEX in SR asthma patients at the present of asthmatic serum may contribute to glucocorticoid insensitivity and the persistent neutrophilia in airways of steroid resistant asthmatics.Part Ⅱ Clara cell 10-kDa protein is a sensitive biomarker to identify Th2 subtype inflammatory phenotypes of asthmaObjective:The present study seeks to determine whether Clara cell 10-kDa protein can be a sensitive biomarker to identify Th2 subtype inflammatory phenotypes of asthma.Methods:Adults with asthma(n = 50)were classified as Th2-high phenotype or Th2-low phenotype asthma based on serum IgE,blood eosinophils,and fraction of exhaled nitric oxide(FeNO).Patients were classified as Th2-high phenotype as follows elevation in two or more biomarkers:high IgE>100 IU/mL,high Eos>300/μL,high FeNO>30 ppb;and Th2-low phenotype as elevation in one or no biomarkers.ELISA was used to assess the CC10 and periostin levels in plasma.All participants underwent sputum induction and different types of inflammatory cells were counted.Results:The level of CC10 in plasma from Th2-low phenotypes were higher than Th2-high phenotypes(P<0.001).The sputum eosinophil proportion from Th2-low phenotypes was higher than Th2-high phenotypes(P<0.001);Sputum neutrophil proportion from Th2-low phenotypes was slightly higher than Th2-high phenotypes,but the difference was statistically significant.The receiver-operating characteristic(ROC)analysis showed a sensitivity of 0.73 and specificity of 0.74 for plasma CC10 of 19.76 ng/ml to distinguish asthmatic patents with Th2-high phenotypes or Th2-low phenotypes.The plasma CC10 level negatively correlated with plasma periostin level(r=-0.4008,p=0.0085),positively correlated with sputum neutrophil proportion(r=0.32,p=0.043)negatively correlated with sputum eosinophil proportion(r=0.3578,p=0.0343),did not correlate with sputum macrophage proportion.The plasma CC10 level positively correlated with forced volume in 1 second(FEV1)%predicted(r=0.343,p=0.02),positively correlated with a-logPD20(Dose producing a decrease of 20%from base line in FEV1)(r=O.349,p=0.04),did not correlate with forced vital capacity(FVC)%predicted,and FEV1/FVC.Conclusions:The plasma CC10 levels for predicting Th2-high and Th2-low phenotypes have important role in patients with asthma.Lower plasma CC10 levels can predict asthma patients with airflow limitation and lower lung function,Th2-high subtype inflammatory and airway hyperresponsiveness.