Figure 6: LTB₄ decreases cAMP and IL-1β production induced by TsV.

(a) Macrophages were pre-treated with LTB₄ (0.01–100 nM, 10 min), before TsV (50 μg ml⁻¹) addition for 24 h. Supernatants were collected for IL-1β quantification. (b) J774.1 macrophages were pre-treated or not with BLT1 antagonist (U-75302, 1 μM, 30 min) and with LTB₄ (100 nM, 10 min) or not before TsV (50 μg ml⁻¹) addition for 24 h. Supernatants were collected for IL-1β quantification. In another set of experiments, (c) J774.1 macrophages were transfected for 48 h to specifically silence Ltb4r1 and Ltbr4r2 gene expression. Cells were then pre-treated or not with LTB₄ (100 nM, 10 min), before TsV (50 μg ml⁻¹) addition for 6 h. In other experiment, (d) Ltb4r1 and Ltb4r2 mRNA expression in C57BL/6 peritoneal macrophages was determined following TsV stimulation (50 μg ml⁻¹) at 2 and 6 h by qRT–PCR. (e) cAMP was determined following stimulation with TsV (50 μg ml⁻¹, 5 min) or PGE₂ (1 μM, 3 min); or LTB₄ (10 nM, 1 min) followed by TsV or PGE₂. (a–e) Data are representative of two independent experiments performed in quadruplicate. Significant differences P<0.05 are marked with symbols and the error bars denote s.d. *Medium only versus stimulus or treatments, and ^#TsV versus treatments, according to one-way ANOVA with Bonferroni’s post-test.