Serum BPI as a novel biomarker in asthma

BACKGROUND: Neutrophils, eosinophils and inflammatory cells contribute to asthmatic inflammation. The anti-bactericidal/permeability-increasing protein (BPI), produced by neutrophils, peripheral blood monocytes or epithelial cells, can neutralize lipopolysaccharide activity and enhance phagocytosis regulation function. This study aimed to assess the clinical significance of BPI in asthmatic patients. METHODS: We recruited 18 controlled asthma, 39 uncontrolled asthma and 35 healthy controls individuals. Clinical characteristics (age, gender, allergy history, body mass index (BMI) and smoking history), clinical indicators [whole blood count, forced expiratory volume in one second as percentage of predicted volume (FEV1% predicted), IgE level, high sensitivity C-reactive protein (hs-CRP) and fractional expiratory nitric oxide (FeNO)] and serum BPI levels were measured to compare among each group. We then evaluated the correlation between BPI, clinical characteristics and clinical indicators. Finally, linear regression analysis was performed to exclude the influence of other factors and to find the independent influencing factors of BPI. RESULTS: Our results showed that the serum BPI levels increased by twofold in the controlled asthma group (12.83 ± 6.04 ng/mL) and threefold in the uncontrolled asthma group (18.10 ± 13.48 ng/mL), compared to the healthy control group (6.00 ± 2.58 ng/mL) (p < 0.001). We further found that serum BPI levels were positively correlated with the hs-CRP (p = 0.002). There was no significant association among BPI, age, gender, BMI, allergy, blood eosinophils, blood neutrophils, IgE, FeNO or FEV1% predicted. CONCLUSION: BPI levels were increased in asthma and positively correlated with hs-CRP. BPI as a potential asthma biomarker that still needs further research.