The Effects Of LXRα In The Anti-inflammatory Mechanisms Of Capsaicin In Vitro

Objectives: The transient receptor potential vanilloid type1(TRPV1) is crucial in theAcute lung injury (ALI); yet its role and underlying mechanism in the formation ofmacrophage cells remain unclear. The objective of present work was to explore therole of liver X receptor α in the anti-inflammatory mechanisms of capsaicin.Methods: The phorbol ester was used to induce THP-1cells to adherent macrophages,then treated with different factors, with a inflammation model induced byLPS.ELISA was used to detect the level of TNF-α, IL-1β, IL-6.Immunohistochemistry and western blot was used to detect LXRα expression ofmacrophages, and semi-quantitative analysis.Results:Our work showed capsaicin had an obvious anti-inflammatory effect, within10μM pre-processed for1h. Compared with control groups (2184.62±68.08), therewas significantly lower expression of LXRα in the LPS treated groups (1755.53±58.98)，a higher expression in capsaicin groups (3193.36±129.61).There wassignificant difference on co-treatment groups of capsaicin and LPS (5221.00±115.32). Expression of protein in each group had a significant difference (p <0.05).Changes of protein measured by Immunohistochemical method were consistent withthe results detected in Western Blot, which indicated that the activation andparticipation of LXRα was necessary in TRPV1signaling pathway when in thenegative regulation of inflammation. In addition, inhibiting activity of LXRα withGGPP could reverse the effects of capsaicin negative regulation of inflammatoryresponse, causing inflammation outbreak.Conclusions: The results above indicated negative regulatory role of capsaicin in LPS-induced inflammation and the anti-inflammatory effect reached optimal afterpretreatment with10μM capsaicin for1h.Expression of LXRα was increased in groupC+L suggesting that LXRα may be involved in anti-inflammatory effects of capsaicin. Atfer LXRα blocked, the anti-inflammatory effect of capsaicin was suppressed orreversed, which indicates LXRα plays a pivotal role in TRPV1-activation-conferredprotection against LPS-induced inflammation in macrophages.