Acanthamoeba castellanii stimulate the production of inflammatory cytokines by a MyD88 dependent, TRIF and PAR2 independent manner

Acanthamoeba castellanii is an opportunistic, facultative parasitic protozoa, known to be the agent of a serious painful potentially blinding keratitis and fatal encephalitis in humans. Acanthamobea keratitis is most prevalent in contact lens wearers where it affects 1 in 30,000. Acanthamoeba are ubiquitous in nature and consequently although individuals are regularly exposed to these amoebae, very few cases of clinical infection occur, suggesting that the innate immune response is normally effective. Monocytes/macrophages express innate immune receptors, such as Toll Like Receptors (TLRs) and Protease Activated receptors (PARs) that are crucial for the recognition and rapid response to pathogens. Herein the role of TLRs and PARs in the recognition and response toAcanthamoeba castellanii are examined. For this purpose, macrophages were obtained from wild-type mice and syngeneic mice deficient in MyD88, TRIF or PAR2 genes. Results demonstrate thatAcanthamoeba castellanii stimulates pro-inflammatory cytokine (IL-6, TNF and IL-12) production by murine macrophages in a MyD88 dependent and TRIF independent manner. Conditioned medium from Acanthamoeba cultures, known to contain secreted proteases, was also able to stimulate the production of pro-inflammatory cytokines, however this event is not PAR-2 dependent. Taken together, these results suggest that TLRs associated signaling pathway plays an important role in initiating the immune response to Acanthamoeba castellanii.