Exploring the immunomodulatory activities of Scoparia dulcis extract against lipopolysaccharide-induced allergic inflammation in mice through suppression of innate pro-inflammatory cytokines, COX-2 and iNOS signalling pathways

Abstract Objectives This study sought to evaluate the biological effects of the hydroethanolic extract of Scoparia dulcis (SDE) on some innate immune responses that are implicated in inflammatory respiratory diseases, using the lipopolysaccharide-induced mice model. Methods Lipopolysaccharide (LPS, 0.5 mg/kg) was dissolved in 2 mL phosphate buffered saline and injected (IP) into mice 1 h after drug administration to induce inflammation and systemic immune responses. Mice were pre-treated with either 10 mg/kg prednisolone or SDE (50, 100, 250 mg/kg, p . o .). The expressions of TNF-α, IL-1β, IL-6, stem cell factor (SCF), nitric oxide (NO), inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 enzymes (COX-2) were evaluated by a real-time PCR technique. Furthermore, histopathological examinations were performed on the lung tissues. Results Pre-treatment with SDE significantly suppressed ( p <0.001) the expressions of TNF-α, SCF, IL-1β, IL-6, and COX-2, as well as iNOS enzymes in the mRNAs of LPS-induced mice, and it also reduced NO levels and endotoxin-induced lung damage. Conclusions SDE exhibited strong immunomodulatory activities and thus, would have potential benefits in immune-inflammatory disease management.