Inter-kingdom Signalling: Exploring the Relationships Among Microorganisms and MicroRNAs in Human Health

Since their discovery in the 1990s, microRNAs have been linked to numerous relevant biological processes such as development, proliferation, and immune response. Any minimal alteration in the expression profiles of these non-coding RNAs had been associated with the onset and development of complex diseases such as cancer or infectious diseases. miRNAs have been unveiled in nearly all domains of life, spanning from viruses to protozoa. Investigating how microRNAs from microorganisms have the capacity to influence host genes opens new avenues for advancing our comprehension of human health. This chapter delves into the signalling frontier between kingdoms, uncovering the multifaceted relationships between microorganisms and miRNAs in the regulation of pathways related to human health. We explore how virus, bacteria, fungi, and protozoa can modulate host messenger RNA expression profiles, allowing evading the immune responses, activating metabolic functions, and even disease susceptibility. Understanding these complex signalling networks offers new insights into a variety of diseases, including infectious diseases and cancer, as well as the potential for innovative therapeutic interventions. This manuscript integrates the most recent findings to provide an overview of the exciting and evolving field of cross-realm signalling, shedding light on connections between microorganisms’ miRNAs in the maintenance of human health.