Macrophage stimulation with <i>Wolbachia</i>-containing preparations induces TLR2-dependent TNFα secretion and tolerance to subsequent LPS stimulation.

<p>Thioglycollate-elicited peritoneal macrophages from wild type and either TLR2- (<b>A</b>), or TLR4-deficient (<b>B</b>) mice were stimulated with TLR4- (<i>E. coli</i>-LPS) and TLR2- (P₃C, FSL1) specific ligands, <i>L. sigmodontis</i> adult worm extract (LsAg), LsAg from <i>Wolbachia</i>-depleted worms (Ls-tet), <i>Wolbachia</i>-infected (Wolb.) and sterile preparations of C6/36 insect cells. TNFα concentrations relative to LPS (<b>A</b>) and P₃C (<b>B</b>) responses are shown. (<b>C</b>) Thioglycollate-induced macrophages from wild type and TLR2-deficient mice were primarily stimulated (prime) for 18 hours as described above before re-stimulation with LPS for an additional 18 hours. TNFα concentrations in supernatants of F4/80^hi macrophages are plotted relative to the acute LPS response (medium prime/LPS stimulation). Shown are data representative of three independent experiments (n = 5/group for (<b>A, B</b>) and n = 3/group for (<b>C</b>)). Data shown is expressed as mean + SEM and was tested for statistical significance by student’s t-test. Asterisks above the bars indicate significant differences compared to med/LPS condition. *p< 0.05; **p< 0.01; ***p<0.001.