Mangiferin ameliorates colitis by inhibiting IRAK1 phosphorylation in NF-κB and MAPK pathways

Mangiferin, a main constituent of the root of Anemarrhena asphodeloides and the leaves of Mangifera indica, inhibits NF-κB activation in macrophages. Therefore, we investigated effect of mangiferin on 2,3,4-trinitrobenzene sulfonic acid (TNBS)-induced colitis in mice and its anti-inflammatory mechanism in lipolysaccharide (LPS)- or peptidoglycan-stimulated mouse peritoneal macrophages. Mangiferin inhibited phosphorylation of nuclear factor-kappaB (NF-κB), interleukin-1 receptor-associated kinase 1 (IRAK1), and mitogen-activated protein kinases (MAPK) in peptidoglycan- or LPS-stimulated peritoneal macrophages. Mangiferin in the presence of SN50 inhibited LPS-stimulated NF-κB activation more potently than mangiferin alone. Mangiferin inhibited interaction of fluorescent p-IRAK1 antibody to LPS-stimulated peritoneal macrophages, but increased binding of fluorescent IRAK1 antibody. Mangiferin did not influence interaction of fluorescent LPS to toll-like receptor-4 on the macrophages. Molecular peak of mangiferin bound to IRAK1 was detected in the macrophages by mass analysis. Mangiferin (10 μM) inhibited LPS-stimulated expression of TNF-α, IL-1β and IL-6 by 81.0%, 89.5% and 88.3%, respectively, whereas it increased IL-10 expression by 131.8% compared to LPS-nontreated group. Mangiferin furthermore inhibited colon shortening, macroscopic score, and colonic myeloperoxidase activity in TNBS-induced colitic mice. Mangiferin inhibited TNBS-induced IRAK1 phosphorylation and NF-κB activation. Mangiferin suppressed TNBS-induced up-regulation of cyclooxygenase-2 and inducible NO synthase. Furthermore, mangiferin (20 mg/kg) significantly inhibited TNF-α by 78%, IL-1β by 82%, and IL-6 expressions by 88% (P<0.05), but induced IL-10 expression to 79% of the normal control group (P<0.05). Based on these findings, mangiferin may ameliorate inflammatory diseases such as colitis by regulating NF-κB and MAPK signaling pathways through the inhibition of IRAK1 phosphorylation.

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