Serum microRNAs catalog asthmatic patients by phenotype

BACKGROUND AND OBJECTIVE

Asthma is a chronic inflammatory condition of the airways with a complex pathophysiology. Stratification of asthma subtypes into phenotypes and endotypes should move the field forward, making treatment more effective and personalized. Eosinophils are the key inflammatory cells involved in severe eosinophilic asthma. Due to the health threat posed by eosinophilic asthma, there is a need for reliable biomarkers to identify patients and treat them properly with novel biologics. A promising tool for diagnosis are microRNAs (miRNAs). Objective: The aim of this study was to find serum miRNAs that can phenotype asthmatic patients.

MATERIAL AND METHODS

Serum miRNAs of eosinophilic (N=40) and non-eosinophilic (N=36) asthmatic individuals were evaluated by next-generation sequencing (NGS), specifically miRNAs-seq, and selected miRNAs were validated by RT-qPCR. Pathways enrichment analysis of deregulated miRNAs was performed.

RESULTS

NGS analysis revealed 15 differentially expressed miRNAs between eosinophilic and non-eosinophilic asthmatic patients, while did not show differences in the miRNome between atopic and non-atopic asthmatic individuals. Of the 15 differentially expressed miRNAs between eosinophilic and non-eosinophilic asthmatics, hsa-miR-26a-1-3p and hsa-miR-376a-3p were validated by RT-qPCR. Expression levels of these two miRNAs were higher in eosinophilic than in non-eosinophilic asthmatics. Furthermore, expression values of hsa-miR-26a-1-3p inversely correlated with peripheral blood eosinophil count and hsa-miR-376a-3p expression values with FeNO values and exacerbations number. Additionally, in silico pathway enrichment analysis revealed that these two miRNAs regulate signaling pathways related with asthma pathogenesis.

CONCLUSIONS

Hsa-miR-26a-1-3p and hsa-miR-376a-3p could be used to distinguish eosinophilic and non-eosinophilic asthmatic patients.

Eosinophil Response Against Classical and Emerging Respiratory Viruses: COVID-19

Eosinophils were discovered more than 140 years ago. These polymorphonuclear leukocytes have a very active metabolism and contain numerous intracellular secretory granules that enable multiple effects on both health and disease status. Classically, eosinophils have been considered important immune cells in the pathogenesis of inflammatory processes (eg, parasitic helminth infections) and allergic or pulmonary diseases (eg, asthma) and are always associated with a type 2 immune response. Furthermore, in recent years, eosinophils have been linked to the immune response by conferring host protection against fungi, bacteria, and viruses, which they recognize through several molecules, such as toll-like receptors and the retinoic acid-inducible gene 1-like receptor. The immune protection provided by eosinophils is exerted through multiple mechanisms and properties. Eosinophils contain numerous cytoplasmatic granules that release cationic proteins, cytokines, chemokines, and other molecules, all of which contribute to their functioning. In addition to the competence of eosinophils as effector cells, their capabilities as antigen-presenting cells enable them to act in multiple situations, thus promoting diverse aspects of the immune response. This review summarizes various aspects of eosinophil biology, with emphasis on the mechanisms used and roles played by eosinophils in host defence against viral infections and response to vaccines. The review focuses on respiratory viruses, such as the new coronavirus, SARS-CoV-2.

Eosinophils: Old Players in a New Game

Eosinophils are terminal polymorphonuclear cells with a high number of cytoplasmic granules that originate in bone marrow. Some are exosomes, which contain multiple molecules, such as specific eosinophilic proteins, cytokines, chemokines, enzymes, and lipid mediators that contribute to the effector role of these cells. Moreover, exosomes present a large number of receptors that allow them to interact with multiple cell types. Eosinophils play an important role in defense against infestations and are a key element in asthma and allergic diseases. Eosinophils are recruited to the inflamed area in response to stimuli, modulating the immune response through the release to the extracellular medium of their granule-derived content. Various mechanisms of degranulation have been identified. Polymorphonuclear leukocytes contain multivesicular bodies that generate exosomes that are secreted into the extracellular environment. Eosinophilic exosomes participate in multiple processes and mechanisms. Eosinophils participate actively in asthma and are hallmarks of the disease. The cells migrate to the inflammatory focus and contribute to epithelial damage and airway remodeling. Given their relevance in this pathology, new therapeutic tools have been developed that target mainly eosinophils and their receptors. In this manuscript, we provide a global, updated vision of the biology of eosinophils and the role of eosinophils in respiratory diseases, particularly asthma. We also summarize asthma treatments linked to eosinophils and new therapeutic strategies based on biological products in which eosinophils and their receptors are the main targets.