Mammalian Toll-like receptors (TLRs) are critical modulators of the immune response to pathogens. TLR recognition of bacteria and some viruses is well known, but there have been few examples of recognition of parasite ligands. Yarovinsky et al. describe detection of a profilin-like protein derived from the protozoan parasite Toxoplasma gondii by a recently characterized mouse TLR, TLR11. The ligand induced the production of the proinflammatory cytokine interleukin-12 (IL-12) by engaging the TLR signaling pathway. In the absence of TLR11, loss of IL-12 production rendered mice susceptible to T. gondii infection. Similar detection of parasite proteins by TLRs may influence the course of immunity against a range of protozoan parasitic diseases.
F. Yarovinsky, D. Zhang, J. F. Andersen, G. L. Bannenberg, C. N. Serhan, M. S. Hayden, S. Hieny, F. S. Sutterwala, R. A. Flavell, S. Ghosh, A. Sher, TLR11 activation of dendritic cells by a protozoan profilin-like protein. Science 308, 1626-1629 (2005). [Abstract] [Full Text]