Fig. 3

Exosomal miRNA in tuberculosis. Mtb PAMPs are identified by TLRs and other pattern recognition receptors, which result in the enhanced expression levels of primary-miRNAs in macrophages. In the nucleus and cytoplasm, these transcripts are cleaved by Drosha and Dicer; sequentially, as a result, the mature miRNAs (18–22 nucleotide) formed and acted to fine-tune intracellular immune processes. The varying miRNA subsets may have a vital role in regulating the particular pathways and components of the immune reactions. Simultaneously, adjacent T lymphocytes implicated in granuloma development/maintenance enhanced T cell subset particular miRNAs as a mechanism of tempering the type of adaptive immune response. Afterward, by the way, not yet entirely comprehended, these extracellular miRNAs proceed from local infection places to the circulatory system. This manner can consequently give rise to infection-specific miRNA expression signatures in circulating that can quickly be evaluated from serum, plasma, sputum, and other biological fluid (Correia et al. 2017). Mtb: Mycobacterium tuberculosis; PAMPs: pathogen-associated molecular patterns; TLRs: toll-like receptors