Short-chain fatty acids act as antiinflammatory mediators by regulating prostaglandin E2 and cytokines

Figure 3 SCFAs strongly induce PGE₂ production in human monocytes and the effect is receptor-mediated. Freshly isolated human monocytes (1 × 10⁹ cells/L) were incubated with the indicated concentrations of SCFAs or 100 nmol/L dexamethasone (Dex), and then cultured for 22 h without (A) or with (B) 100 ng/mL LPS. In a separate experiment (C, D), human monocytes were incubated with the indicated concentrations (in the parentheses) of inhibitors (described below) for 30 min, then with or without 2 mmol/L butyrate for another 30 min, and finally cultured for 22 h without (C) or with (D) 100 ng/mL LPS. The media and DMSO samples were used as controls with no inhibitors. All culture supernatants were assayed for PGE₂ by ELISA. MLnFP (methyl α-linolenyl fluorophosphonate): Phospholipase inhibitor; 1400W: Selective iNOS inhibitor; SC-560: Selective cyclooxygenase-1 (COX-1) inhibitor; CAY10404: Selective COX-2 inhibitor; PTX: Pertussis toxin. (Cayman Chemical, Ann Arbor, MI). The tested concentrations of each inhibitor (except PTX) were chosen to be about 100 times its IC₅₀ as reported in the data sheet provided by the manufacturer.