B. abortus RNA is the component involved in the down-modulation of MHC-I expression on human monocytes via TLR8 and the EGFR pathway
Fig 4
B. abortus RNA degradation products are also capable of inhibiting the IFN-γ-induced expression of MHC-I.
(A) RNA from B abortus was purified and treated with DNase, Proteinase K (PK) or E. coli RNase I. Each treatment was visualized by 1% agarose gel electrophoresis. (B and C) THP-1 cells were stimulated with DNase (B) or PK (C)–treated B. abortus RNA in the presence of IFN-γ for 48 h. Cells treated with DNase or PK alone were used as negative controls. Cells treated with B. abortus RNA were used as positive controls. (D and E) THP-1 cells were treated with RNase I-treated B. abortus RNA in the presence of IFN-γ for 48 h. Cells treated only with RNase I were used as negative controls. Cells treated with B. abortus RNA were used as positive controls. MHC-I was assessed by flow cytometry. Bars represent the arithmetic means ± SEM of five experiments. MFI, mean fluorescence intensity. *P<0.05; **P<0.01; ***P<0.001 vs. IFN-γ-treated. ##P<0.01; ###P<0.001 vs. negative controls.