Biomarcadores exosomales: nuevas perspectivas para el diagnóstico y pronóstico de las enfermedades respiratorias

. Exosomes are small vesicles secreted by host cells after degradation of inert particles or microorganisms. Their size of < 0.1 μ m allows them to migrate from the lung to different organs, carrying within them micro RNAs (miRNAs) and other host molecules. It has been reported that in non-infectious lung diseases, such as cancer, asthma, and pulmonary fibrosis, as well as in infectious diseases, such as influenza, COVID-19, pneumonia, and tuberculosis, there is a differential expression of miRNAs, and they have been proposed as biomarkers for diagnosis and/ or as possible therapeutic targets. Additionally, in infectious diseases, both pathogen genetic material and host miRNAs have been found in exosomes with bimodal regulatory functions, that is, they may participate either in promoting infection or controlling disease progression. In infection with influenza viruses and SARS-CoV-2, exosomes can directly block entry into host cells by expressing the receptor on their own surface, thus suggesting them as therapeutic targets. Additionally, another function of exosomal miRNAs is as new vaccines for active and latent tuberculosis. Most of the biomarkers are still in the preclinical phase, so clinical studies are required to evaluate their efficacy as biomarkers for the diagnosis of pulmonary diseases. In this review we will focus on the most relevant information on the role of exosomal RNAs and their function in lung diseases caused by infectious and non-infectious agents, as biomarkers for diagnosis and as prognostic biomarkers, and their possible therapeutic use.