ABSTRACT
BACKGROUND: Tetrahydrocurcumin (THC) is the major active metabolite of curcumin, which is a dietary factor derived from Curcuma species. Our previous study demonstrated a significant beneficial effect of THC in mice with allergic asthma. Glucocorticosteroids (GCs) are commonly used drugs in asthma. Whether THC supplementation could promote the beneficial effects of GC therapy on asthma has not yet been reported. The current study aimed to investigate the combined efficacy of GC and THC treatment in a mouse model of allergic asthma. METHODS: BALB/c mice were randomly divided into 5 groups: the control group, ovalbumin (OVA)-induced group, and OVA-induced mice treated with dietary THC only, intraperitoneal injection of dexamethasone (DEX) only, or THC combined with DEX. The nasal symptoms, histopathological alterations of lung tissues, lung cytokine production, and Th cell subsets were assessed. RESULTS: THC or DEX had beneficial effects on nasal symptoms and pathological lung changes, and the therapeutic effects between THC and DEX treatment were comparable. Importantly, compared to the monotherapy groups (THC or DEX only), the combination of THC and DEX showed a significantly reduced nasal rubbing frequency, lower mucus hyperproduction, lower Th2 and Th17 cell numbers as well as lower related cytokine levels (IL-4, IL-5, and IL-17A). CONCLUSIONS: Supplementation with THC can enhance the therapeutic effects of DEX to alleviate airway symptoms, lung inflammation, and the Th2 response. Our findings suggest that dietary administration of THC could act as an add-on therapy for asthma treated with GCs.