Critical Roles of Micro-RNAs in the Pathogenesis and Immunoregulation of Leishmania Infection

The genus Leishmania was first described in 1903 with the highly pathogenic species L. donovani, but several other pathogenic species have been reported after that. These species, endemic in more than 98 countries, are associated with morbidity, mortality, and economic losses. Leishmania is transmitted to the mammalian host by the bite of infected female phlebotomine sandflies, leading to a wide range of symptoms from skin lesions to fatal leishmaniasis, depending on the species. These protozoan parasites strategically alter the host’s immunity to survive and replicate within the host. Over the past decade, micro-RNAs (miRNAs) have been reported to regulate both acquired and innate immunity in the host, especially during infection and disease states. miRNAs, noncoding single-stranded RNA molecules, regulate gene expression processes at the post-transcriptional level. Recent evidence has shown that miRNAs also play a critical role in immune regulation during leishmaniasis. This chapter will discuss how miRNAs regulate different biological processes during cell growth and develop-ment, proliferation, inflammation, cell-cell interaction, and immune response modulation during infection with Leishmania parasites. We will also highlight the potential diagnostic and prognostic uses of miRNAs against leishmaniasis.