Anti-inflammation of isoliquiritigenin via the inhibition of NF-κB and MAPK in LPS-stimulated MAC-T cells.

Abstract

BACKGROUND: The application of plant extracts has received great interest for the treatment of bovine mastitis. Isoliquiritigenin (ISL) is a rich dietary flavonoid that has significant antioxidative, anti-inflammatory and anticancer activities. This study was conducted to explore the protective efficacy and related mechanism of ISL against lipopolysaccharide (LPS)-stimulated oxidation and inflammation in bovine mammary epithelial cells (MAC-T) by in vitro experiments. RESULTS: Real-time PCR and ELISA assays indicated that ISL treatment at 2.5, 5 and 10 &#x3bc;g/mL significantly reduced the mRNA and protein expression of the oxidative indicators cyclooxygenase-2 and inducible nitric oxide synthase (P < 0.01), and of the inflammatory cytokines interleukin-6 (P < 0.05), interleukin-1&#x3b2; (P < 0.01) and tumor necrosis factor-&#x3b1; (P < 0.01) in LPS-stimulated MAC-T cells. Moreover, Western blotting and immunofluorescence tests indicated that the phosphorylation levels of nuclear factor kappa (NF-&#x3ba;B) p65 and the inhibitor of NF-&#x3ba;B were significantly decreased by ISL treatment, thus blocking the nuclear transfer of NF-&#x3ba;B p65. In addition, ISL attenuated the phosphorylation levels of p38, extracellular signal-regulated kinase and c-jun NH2 terminal kinase. CONCLUSIONS: Our data demonstrated that ISL downregulated the LPS-induced inflammatory response in MAC-T cells. The anti-inflammatory and antioxidative activity of ISL involves the NF-&#x3ba;B and MAPK cascades.