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Severe cases of COVID‐19 present hyperinflammatory condition that can be fatal. Little is known about the role of regulatory responses in SARS‐CoV‐2 infection. In this study, we evaluated the phenotype of regulatory T cells in the blood (peripheral blood mononuclear cell) and the lungs (broncho‐alveolar) of adult patients with severe COVID‐19 under invasive mechanical ventilation. Our results show important dynamic variation on Treg cells phenotype during COVID‐19 with changes in number and functional parameters from the day of intubation (Day 1 of intensive care unit admission) to Day 7. We observed that compared with surviving patients, non‐survivors presented lower numbers of Treg cells in the blood. In addition, lung Tregs of non‐survivors also displayed higher PD1 and lower FOXP3 expressions suggesting dysfunctional phenotype. Further signs of Treg dysregulation were observed in non‐survivors such as limited production of IL‐10 in the lungs and higher production of IL‐17A in the blood and in the lungs, which were associated with increased PD1 expression. These findings were also associated with lower pulmonary levels of Treg‐stimulating factors like TNF and IL‐2. Tregs in the blood and lungs are profoundly dysfunctional in non‐surviving COVID‐19 patients. [ABSTRACT FROM AUTHOR]

Background: Increased levels of inflammatory cytokines are associated with severe dengue evolution, but the source of such hypercytokinemia is elusive. We investigated the contribution of innate lymphocytes, innate lymphoid cells (ILCs), and natural killer (NK) cells in cytokine production in early dengue infection.Methods: Peripheral blood mononuclear cells of individuals with dengue without warning signs (DWS-) and dengue with warning signs and severe dengue (SD) presentation combined (DWS+) were obtained between 2 and 7 days since fever onset and submitted to flow cytometry without specific antigen stimulation to evaluate cytokines in ILC and NK cell subpopulations.Results: ILCs and NK cells were found to be important sources of cytokines during dengue. ILCs of the DWS+/SD group displayed higher production of interferon gamma (IFN-γ) and interleukin (IL) 4/IL-13 when compared to DWS- individuals. On the other hand, NK Eomes+ cells of DWS- patients displayed higher IFN-γ production levels compared with the DWS+/SD group. Interestingly, when NK cells were identified by CD56 expression, DWS+/SD displayed higher frequency of IL-17 production compared with the DWS- group.Conclusions: These results indicate that ILCs and NK cells are important sources of inflammatory cytokines during acute dengue infection and display distinct profiles associated with different clinical forms. [ABSTRACT FROM AUTHOR]

The world population's life expectancy is growing, and neurodegenerative disorders common in old age require more efficient therapies. In this context, neural stem cells (NSCs) are imperative for the development and maintenance of the functioning of the nervous system and have broad therapeutic applicability for neurodegenerative diseases. Therefore, knowing all the mechanisms that govern the self-renewal, differentiation, and cell signaling of NSC is necessary. This review will address some of these aspects, including the role of growth and transcription factors, epigenetic modulators, microRNAs, and extracellular matrix components. Furthermore, differentiation and transdifferentiation processes will be addressed as therapeutic strategies showing their significance for stem cell-based therapy. [ABSTRACT FROM AUTHOR]