No abstract

Exosomes are extracellular vesicles characterized by their size, source, release mechanism and contents. MicroRNAs (miRNAs) are single stranded non-coding RNAs transcribed from DNA. Exosomes and miRNAs are widespread in eukaryotic cells, especially in mesenchymal stem cells (MSCs). MSCs are used for tissue regeneration, and also exert paracrine, anti-inflammatory and immunomodulatory effects. However, the use of MSCs is controversial, especially in the presence or after the remission of a tumor, due to their secretion of growth factors and their migration ability. Instead of intact MSCs, MSC-derived compartments or substances could be used as practical tools for diagnosis, follow up, management and monitoring of diseases. Herein, we discuss some aspects of exosomal miRNAs derived from MSCs in the progression, diagnosis and treatment of various diseases.

No abstract

Coronavirus disease 2019 (COVID-19), an acute respiratory infection, is largely associated with dysregulation and impairment of the immune system. This study investigated how the immune system changes were related to disease severity in COVID-19 patients. The frequencies of different immune cells and levels of pro- and anti-inflammatory cytokines in whole blood of participants were determined by flow cytometry and enzyme-linked immunosorbent assay, respectively. The values of other inflammatory agents were also studied. In the late recovery stage, unlike CD56high CD16+/− NK cells and monocytes, CD56low CD16+ NK cell numbers were increased ( P < 0.0001–0.05). Th1, Th2, and Th17 cell percentages were significantly lower in patients than healthy control ( P < 0.0001–0.05), while their frequencies were increased following disease recovery ( P < 0.0001–0.05). The numbers of Tregs, activated CD4+ T cells, and exhausted CD8+ T cells were significantly decreased during a recovery ( P < 0.0001–0.05). No significant change was observed in exhausted CD4+ T cell number during a recovery ( P > 0.05). B cell showed an increased percentage in patients compared to healthy subjects ( P < 0.0001–0.05), whereas its number was reduced following recovery ( P < 0.0001–0.05). IL-1α, IL-1β, IL-6, TNF-α, and IL-10 levels were significantly decreased in the late recovery stage ( P < 0.0001–0.05). However, TGF-β1 level was not significantly changed during the recovery ( P > 0.05). Lymphocyte numbers in patients were significantly decreased ( P < 0.001), unlike ESR value ( P < 0.001). Lymphocyte number was negatively correlated to ESR value and Th2 number ( P < 0.05), while its association with monocyte was significantly positive at the first day of recovery ( P < 0.05). The immune system changes during the disease recovery to improve and regulate immune responses and thereby may associate with the reduction in disease severity.