Parasitic Infections and MicroRNAs

Some parasites are innocuous or even beneficial to mammalian hosts. The gastrointestinal helminths modulate several important intestinal functions such as immunomodulation. In contrast, infections by pathogenic parasites are the cause of numerous epidemics and serious disease. The inflammatory response to infection must be tightly regulated in order to achieve pathogen clearance and at the same time avoid consequences of deregulated gene expression. The discovery in eukaryotic cells of small non-coding RNAs called microRNAs (miRNAs) has greatly expanded our understanding of the mechanisms that regulate gene expression. Recently, the miRNAs biosynthesis and mechanism of action are well documented. Regarding their mechanism of action, miRNAs most often silence gene expression following association with mRNA targets and Argonaute proteins (Ago), thereby forming the miRNA-induced silencing complex (miRISC). Numerous miRNAs can also be identified in extracellular compartments for example when associated with Ago in plasma, or when contained within exosomes, small membrane vesicles that bud off the cell surface into the extracellular space. These biofluid miRNAs have increasingly been validated as robust biomarkers for disease and organ damage