PGE₂-EP4 pathway is in charge of LF41-mediated attenuation of hepatic TNF-α expression.

<p><b>(A)</b> ELISA for PGE₂ secretion by the terminal ileum and total PGE₂ levels in the liver of mice (n = 8) orally treated either for 10 days with PBS, L-LF41, or H-LF41, or for 3 weeks with PBS or H-LF41. * P < 0.05 PBS. <b>(B)</b> ELISA for hepatic IL-10 protein concentration of mice (n = 8) fed either PBS or H-LF41 for 10 days. P > 0.05 compared to PBS. <b>(C)</b> q-PCR for hepatic <i>Cox1</i> or <i>Cox2</i> mRNA levels of mice (n = 8) fed either PBS or H-LF41 for 10 days. Results are expressed as fold change relative to PBS. P > 0.05 compared to PBS. <b>(D)</b> Western blot assay for representative hepatic COX-1 and COX-2 protein levels of mice (n = 4) orally treated with either PBS or H-LF41 for 10 days. Hepatic COX-2 protein levels from a mouse receiving 2 h of stimulation with LPS (0.5 mg/kg BW; single IP injection) were determined as a positive control (left lane). <b>(E)</b> Mice (H-LF41-treated groups: n = 10 per group; PBS-treated groups: n = 8 per group) were pretreated with 10 days of PBS or H-LF41, either alone or combined with administration of either a specific inhibitor for PGE₂ receptor EP-4, ONA-AE3-208 (I-EP4), or its vehicle (Vehicle). Hepatic <i>Tnf</i> mRNA levels were assayed by q-PCR 2 h after LPS treatment. Results are expressed as fold change relative to PBS+LPS.* P < 0.05; <b>&</b> P < 0.05 compared to H-LF41+LPS; <b>n.s.</b>, non-statistical difference. All values except that of Western blot are shown as mean ± SEM. Results are representative of 2 similar experiments.