ABSTRACT
T-helper subtype imbalance is intricate in type 1 diabetes (T1D) and asthma initiation. The role of quercetin in immunedysregulation in comorbid conditions of T1D and asthma is not available. In this study, it was thought worthy toevaluate the role of quercetin on modulating Th1/Th2 cytokine dysregulation in comorbid diabetic asthma. Male Balb/cmice were injected intravenously with alloxan (80 mg/kg) to persuade T1D. Succeeding diabetes introduction, twointraperitoneal sensitizing doses of ovalbumin emulsion (50 µg ovalbumin blended with 2.5 mg alum/sensitization) weregiven on days 3 and 8. Mice were given intranasal challenges of ovalbumin (100 µg ovalbumin/25 µl of sterile saline) ondays 13–15. Oral quercetin treatment (10–30 mg/kg) was given daily on days 3–15. Nasal hyperresponsiveness (NHR)was recorded immediately after Ova challenge on day 16. Bronchoalveolar lavage fluid (BALF), blood, and lungs werecollected 1-hour post NHR for further analysis. Quercetin treatment significantly decreased eosinophils, interleukin-4while increasing interferon-gamma in blood, and BALF and reduced the allergic airway inflammation by inhibitinginflammatory cell infiltration and mucous cell metaplasia. Furthermore, quercetin with a dose of 30 mg/kg demonstrateda significant glucose reduction. Thus, quercetin exerted dose-dependent anti-asthma activity by modulating Th1/Th2balance with glucose-lowering potential in comorbid mice.