Immunomodulatory and Anti-Inflammatory Potential of Curcumin for the Treatment of Allergic Asthma: Effects on Expression Levels of Pro-inflammatory Cytokines and Aquaporins

Curcumin is well known for possessing anti-inflammatory properties and for its beneficial effects in the treatment of asthma. Current study investigates the immunomodulatory and anti-inflammatory effects of curcumin using mouse model of ovalbumin-induced allergic asthma. BALB/c mice were immunized with ovalbumin on day 0 and 14 to induce allergic asthma. Animals were treated with two different doses of curcumin (20 mg/kg and 100 mg/kg) and methylprednisolone from day 21 to 28. Mice were also daily challenged intranasally with ovalbumin during treatment period, and all groups were sacrificed at day 28. Histopathological examination showed amelioration of allergic asthma in treated groups as evident by the attenuation of infiltration of inflammatory cells, goblet cell hyperplasia, alveolar thickening, and edema and vascular congestion. Curcumin significantly reduced total and differential leukocyte counts in both bronchoalveolar lavage fluid and blood. Reverse transcription polymerase chain reaction analysis showed significantly suppressed mRNA expression levels of IL-4 and IL-5 (pro-inflammatory cytokines), TNF-α, TGF-β (pro-fibrotic cytokines), eotaxin (chemokine), and heat shock protein 70 (marker of airway obstruction) in treated groups. Attenuation of these pro-inflammatory markers might have led to the suppression of airway inflammation. The expression levels of aquaporin-1 (AQP) and AQP-5 were found significantly elevated in experimental groups which might be responsible for reduction of pulmonary edema. In conclusion, curcumin significantly ameliorated allergic asthma. The anti-asthmatic effect might be attributed to the suppression of pro-inflammatory cytokines, and elevation of aquaporin expression levels, suggesting further studies and clinical trials to establish its candidature in the treatment of allergic asthma.