microRNAs (miRNAs) are small, non-coding RNA molecules that play
crucial regulatory roles in numerous cellular processes. Recent
investigations have highlighted the significant involvement of miRNA-122
(miR-122) in the pathogenesis of infectious diseases caused by diverse
pathogens, encompassing viral, bacterial, and parasitic infections. In
the context of viral infections, miR-122 exerts regulatory control over
viral replication by binding to the viral genome and modulating the
hosts antiviral response. For instance, in hepatitis B virus (HBV)
infection, miR-122 restricts viral replication, while HBV, in turn,
suppresses miR-122 expression. Conversely, miR-122 interacts with the
hepatitis C virus (HCV) genome, facilitating viral replication.
Regarding bacterial infections, miR-122 has been found to regulate host
immune responses by influencing inflammatory cytokine production and
phagocytosis. In Vibrio anguillarum infections, there is a significant
reduction in miR-122 expression, contributing to the pathophysiology of
bacterial infections. Toll-like receptor 14 (TLR14) has been identified
as a novel target gene of miR-122, affecting inflammatory and immune
responses. In the context of parasitic infections, miR-122 plays a
crucial role in regulating host lipid metabolism and immune responses.
For example, during Leishmania infection, miR-122-containing
extracellular vesicles from liver cells are unable to enter infected
macrophages, leading to a suppression of the inflammatory response.
Furthermore, miR-122 exhibits promise as a potential biomarker for
various infectious diseases. Its expression level in body fluids,
particularly in serum and plasma, correlates with disease severity and
treatment response in patients affected by HCV, HBV, and tuberculosis.
This paper also discusses the potential of miR-122 as a biomarker in
infectious diseases. In summary, this review provides a comprehensive
and insightful overview of the emerging role of miR-122 in infectious
diseases, detailing its mechanism of action and potential implications
for the development of novel therapeutic strategies.