Difference in Strain Pathogenicity of Septicemic Yersinia pestis Infection in a TLR2−/− Mouse Model

ABSTRACT Yersinia pestis is the causative agent of bubonic, pneumonic, and septicemic plague. We demonstrate that Toll-like receptor 2-deficient (TLR2−/−) mice are resistant to septicemic infection by the KIM5 strain of Y. pestis but not to infection by the CO92 Δpgm strain. This resistance is dependent on TLR2, the route of infection, and the isoform of YopJ. Elevated bacterial burdens were found in the spleens of CO92 Δpgm-infected animals by 24 h postinfection and in the livers by 4 days. The YopJ isoform present contributed directly to cytotoxicity and inflammatory cytokine production of bone marrow-derived macrophages from TLR2−/− mice. Immune cell trafficking is altered in CO92 Δpgm infections, with an increased neutrophil infiltration to the spleen 5 days postinfection. Immune cell infiltration to the liver was greater and earlier in KIM5-infected TLR2−/− mice. The functionality of the immune cells was assessed by the ability to develop reactive oxygen and nitrogen species. Our data suggest an inhibition of granulocytes in forming these species in CO92 Δpgm-infected TLR2−/− mice. These findings suggest that resistance to KIM5 in TLR2−/− mice is dependent on early immune cell trafficking and functionality.

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Cytadherence of Mycoplasma pneumoniae Induces Inflammatory Responses through Autophagy and Toll-Like Receptor 4

Infection and Immunity ◽

10.1128/iai.01961-14 ◽

2014 ◽

Vol 82 (7) ◽

pp. 3076-3086 ◽

Cited By ~ 38

Author(s):

Takashi Shimizu ◽

Yui Kimura ◽

Yutaka Kida ◽

Koichi Kuwano ◽

Masato Tachibana ◽

...

Keyword(s):

Immune Responses ◽

Mycoplasma Pneumoniae ◽

Cytokine Production ◽

Inflammatory Responses ◽

Hypothetical Protein ◽

Toll Like Receptor ◽

Wild Type ◽

Toll Like Receptor 4 ◽

Content Type ◽

Toll Like Receptor 2

ABSTRACTMycoplasma pneumoniaecauses pneumonia, tracheobronchitis, pharyngitis, and asthma in humans. The pathogenesis ofM. pneumoniaeinfection is attributed to excessive immune responses. We previously demonstrated thatM. pneumoniaelipoproteins induced inflammatory responses through Toll-like receptor 2 (TLR2). In the present study, we demonstrated thatM. pneumoniaeinduced strong inflammatory responses in macrophages derived from TLR2 knockout (KO) mice. Cytokine production in TLR2 KO macrophages was increased compared with that in the macrophages of wild-type (WT) mice. Heat-killed, antibiotic-treated, and overgrownM. pneumoniaefailed to induce inflammatory responses in TLR2 KO macrophages. 3-Methyladenine and chloroquine, inhibitors of autophagy, decreased the induction of inflammatory responses in TLR2 KO macrophages. These inflammatory responses were also inhibited in macrophages treated with the TLR4 inhibitor VIPER and those obtained from TLR2 and TLR4 (TLR2/4) double-KO mice. Two mutants that lacked the ability to induce inflammatory responses in TLR2 KO macrophages were obtained by transposon mutagenesis. The transposons were inserted inatpCencoding an ATP synthase F0F1 ε subunit andF10_orf750encoding hypothetical protein MPN333. These mutants showed deficiencies in cytadherence. These results suggest that cytadherence ofM. pneumoniaeinduces inflammatory responses through TLR4 and autophagy.

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