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. 2022 Apr 1;13:823685. doi: 10.3389/fimmu.2022.823685

Figure 2.

Figure 2

Fimbriae purified from the wild-type ATCC 33277 strain activate the TLR2 receptor. U251 MG cells overexpressing TLR2 were: (A) infected for 4 h with WT ATCC 33277 and its isogenic major fimbriae (delFimA) mutant strain (MOI=100), n=4-5 (B) infected for 4 h with various ATCC 33277-derived PPAD and FimA mutants as well as the WT W83 strain at different MOI (all strains MOI=20-100 with an additional MOI=5 for WT ATCC 33277), n=3 or (C) infected for 2, 4 or 6 h with WT ATCC 33277 or the PPAD mutant strains (MOI=100), n=3; and (D) treated for 4 h with purified fimbriae (10 µg/ml) from WT ATCC 332771 (FimA WT) or the PPAD mutant (FimA delPPAD) strains; n=4. Results are presented as the mean ± SD ratio of Firefly luciferase activity to β-galactosidase activity and are normalized to cells stimulated/infected with the same factor and transfected with an empty vector. (E) HEK Blue cells overexpressing TLR2 were treated with purified fimbriae (10 µg/ml) isolated from the WT ATCC 33277 strain (FimA WT) or the PPAD mutant (FimA delPPAD), n=3. Results are presented as the mean ± SD fold induction compared to control (unstimulated) cells. ****p < 0.0001; ***p < 0.001; **p < 0.01; *p < 0.05; ns, no statistical significance. 1-way ANOVA followed by Tukey’s multiple comparisons test. In (B) each condition was compared to control uninfected cells and in (C) comparisons were performed for each timepoint separately and significant differences compared to WT ATCC 33277 are depicted in the graph.