Contributions of the MyD88-dependent receptors IL-18R, IL-1R, and TLR9 to host defenses following pulmonary challenge with Cryptococcus neoformans
Wang, Jennifer P. ; Lee, Chrono K. ; Akalin, Ali ; Finberg, Robert W. ; Levitz, Stuart M
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Abstract
Signaling via the adapter protein, MyD88, is important in the host defense against Cryptococcus neoformans infection. While certain Toll-like receptors (TLRs) can enhance the clearance of Cryptococcus, the contributions of MyD88-dependent, TLR-independent pathways have not been fully investigated. We examined the roles of IL-1R and IL-18R in vivo by challenging C57BL/6 mice with a lethal strain of Cryptococcus. We found that the absence of IL-18R, but not IL-1R, causes a shift in the survival curve following pulmonary delivery of a virulent strain of C. neoformans (H99). Specifically, IL-18R-deficient mice have significantly shorter median survival times compared to wild-type mice following infection. Cytokine analysis of lung homogenates revealed that deficiency of IL-IR, IL-18R, or MyD88 is associated with diminished lung levels of IL-1beta. In order to compare these findings with those related to TLR-deficiency, we studied the effects of TLR9-deficiency and found that deficiency of TLR9 also affects the survival curve of mice following challenge with C. neoformans. Yet the lungs from infected TLR9-deficient mice have robust levels of IL-1beta. In summary, we found that multiple signaling components can contribute the MyD88-dependent host responses to cryptococcal infection in vivo and each drives distinct pulmonary responses.
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Wang JP, Lee CK, Akalin A, Finberg RW, Levitz SM (2011) Contributions of the MyD88-Dependent Receptors IL-18R, IL-1R, and TLR9 to Host Defenses following Pulmonary Challenge with Cryptococcus neoformans. PLoS ONE 6(10): e26232. doi:10.1371/journal.pone.0026232. Link to article on publisher's site