Background: MicroRNAs (miRNAs) are a subset of small regulatory RNAs that are expressed by almost all metazoans and protozoans. They express genes either by direct cleavage or by suppressing the translation of target mRNAs by partial complementary base pairing. The active and functional unit of miRNA is a complex of Argonaute proteins known as microRNA-induced silencing complex (miRISC). They are known to regulate various growth and physiological processes. Irregular expression of miRNA in human cells is associated with a variety of disorders such as cancer, cardiovascular dysfunction, liver damage, immune dysfunction, metabolic syndromes, and pathogenic infections.
A growing number of studies have shown that miRNAs are in fact a major component of host interactions and pathogens and play an important role in host immune responses to microorganisms. Emerging miRNAs are recognized as important tools for the genetic study, therapeutic development, and diagnosis of human pathogenic infections caused by various pathogenic organisms such as viruses, bacteria, parasites, and fungi. Many pathogens use the host miRNA system for their own benefits, including pathogenesis, survival within the host cell, and crossing some host immune barriers. Other pathogens express their miRNA within the host and contribute to their replication, survival, or delay. This article aims to review the role and importance of miRNA in relation to some important parasitic diseases.
