Subversion of host cell signalling by the protozoan parasiteLeishmania

Abstract

The protozoaLeishmaniaspp. are obligate intracellular parasites that inhabit the macrophages of their host. Since macrophages are specialized for the identification and destruction of invading pathogens, both directly and by triggering an innate immune response,Leishmaniahave evolved a number of mechanisms for suppressing some critical macrophage activities. In this review, we discuss how various species ofLeishmaniadistort the host macrophage's own signalling pathways to repress the expression of various cytokines and microbicidal molecules (nitric oxide and reactive oxygen species), and antigen presentation. In particular, we describe how MAP Kinase and JAK/STAT cascades are repressed, and intracellular Ca2+and the activities of protein tyrosine phosphatases, in particular SHP-1, are elevated.