Protective effects of ascorbic acid and calcitriol combination on airway remodelling in ovalbumin-induced chronic asthma

CONTEXT: Airway remodelling is one of the most refractory problems in asthma. According to the critical roles of oxidative stress and inflammation in airway remodelling, it is supposed that ascorbic acid and calcitriol have beneficial effects. However, a combination of antioxidants may be more effective for asthma therapy. OBJECTIVE: This study investigated the protective effects of ascorbic acid in combination with calcitriol on airway remodelling in ovalbumin (OVA)-induced chronic asthma. MATERIALS AND METHODS: BALB/c mice were assigned into seven groups: (1) Control; (2) Asthma; (3) Ineffective C (orally 39 mg/kg ascorbic acid); (4) Ineffective D (intraperitoneally 1.5 μg/kg calcitriol); (5) Effective C (orally 130 mg/kg ascorbic acid); (6) Effective D (intraperitoneally 5 μg/kg calcitriol); (7) Combination (orally 39 mg/kg ascorbic acid + intraperitoneally 1.5 μg/kg calcitriol). All animals were sensitized and challenged with OVA except in the control group (normal saline). In all treatment groups, mice were administrated vitamins 30 min before each challenge (three times per week for 8 consecutive weeks). RESULTS: In comparison with the asthma group, co-administration of ineffective doses of ascorbic acid and calcitriol led to the decreased levels of IL-13 (50.5 ± 1.85 vs. 42.13 ± 0.37 pg/mL, p = 0.02) and IgE (58.74 ± 0.43 vs. 45.78 ± 2.05 ng/mL, p = 0.003) as well as the reduction of goblet hyperplasia and subepithelial fibrosis (5 vs. 1 score, p = 0.001 and 5 vs. 2 score, p = 0.001, respectively). DISCUSSION AND CONCLUSIONS: Combination of ascorbic acid with calcitriol in ineffective doses improves airway remodelling due to additive effects possibly through reduction of oxidative stress and inflammation. This study provides a scientific basis for further research and clinical applications of ascorbic acid and calcitriol and can be generalized to the broader pharmacological studies.