Editorial: Exosomes and exosomal miRNAs as biomarkers in infection with Mycobacterium tuberculosis

In the study of tuberculosis, both pathogen-and host-based biomarkers have been extensively researched. These include hematologic markers, proteins, a number of metabolites, and signatures that incorporate many markers and have been found using unbiased "omics" discovery approaches [6][7][8]. However, the research findings are inconsistent, and there are still pitfalls and limitations in translating biomarker discoveries into clinical applications. Hence, more effort is needed to succeed in this field. miRNAs are small non-coding RNAs that fine-tune complex biological processes by regulating the key proteins in molecular signaling networks. Due to their varying expression patterns in healthy, latent, and active TB populations as well as in different types of tuberculosis, these molecules have gained more attention as possible biomarkers in the TB field [9,10].In addition, miRNAs have determinant roles in the outcome of Mycobacterium tuberculosis (Mtb) infection [9]. Mtb subverts the host miRNA network to modulate host cell signaling pathways favoring intracellular survival [11].Mtb infection leads to host immune and metabolic repatterning, which enables Mtb to perturb the autophagy and apoptosis of infected cells and maintain their nutritional and energy requirements.This process involves the modulation of host miRNAs that control the regulatory networks associated with cell metabolism and immunity in the infected cells [11,12].The TB-dysregulated host miRNAs may be shuttled across the cells' membranous organelles, such as exosomes.Most cell types produce bioactive exosomes, which are 30-100 nm nanovesicles that carry a complex cargo of biomolecules from the original cell. Circulating exosomes are highly stable in biological fluids and therefore provide a great deal of information about the physiological and pathological status of the originating cell. These properties have fulfilled their promise as diagnostic biomarkers, enabling noninvasive clinical diagnosis [13].Numerous recent studies have shown the importance of exosomes and exosomal miRNAs in the fate of TB. It has been shown that the amount and composition of miRNAs packaged into exosomes (exosomal miRNAs) are different in infected versus uninfected macrophages, and also in the serum exosomes from TB patients versus healthy subjects [14][15][16]. Exosomal miRNAs may be useful in the detection and monitoring of tuberculosis, according to these findings.Despite the advances in understanding the content of Mtb and Mtb-infected host extracellular vesicles, our understanding of the biogenesis and role of extracellular vesicles during Mtb infection is still nascent. Furthermore, understanding the physiology and mechanisms of Mtb, and the mechanisms of orchestration of the host immune system against the bacteria can be interesting research fields to have a better understanding of the pathogenesis of the disease and to improve TB management.In this research topic, we have gathered four studies covering these areas of research. Even with current progress in the fundamental research in the field of tuberculosis, we still need to deepen our understanding of the mechanisms of M. tuberculosis as well as the function of the host immune system to find suitable biomarkers and make a breakthrough in TB management, to ultimately meet the goals of the WHO to eradicate TB by 2035.