miR-199a-5p targeted regulation of MAGT1 expression in the functional depletion of CD8+T cells in HBV infection.

Magnesium transporter 1 (MAGT1) is a key protein that regulates the level of free Mg2+ in cells. Previous studies found that the downregulation of MAGT1 expression in CD8+T cells of HBV patients was correlated with the decrease of intracellular magnesium. However, the expression of MAGT1 mRNA in the CD8+T cells from HBV patients was not significantly altered, indicating that the change in MAGT1 expression was accomplished through posttranscriptional regulation. Through bioinformatics and qRT-PCR detection, miR-199a-5p was found to have a target gene relationship with MAGT1. The expression levels of miR-199a-5p and MAGT1 in HBV infection were evaluated. Lentivirus assays were used to analyze the effects of miR-199a-5p upregulation and downregulation on the MAGT1 expression level and the immune system. Results showed no significant change in the expression of MAGT1 mRNA in HBV-infected cell lines, but the expression of MAGT1 was downregulated. Additionally, the expression level of miR-199a-5p was significantly increased. To this end, we predicted a target relationship between miR-199a-5p and MAGT1 by using TargetScan and verified this relationship through a luciferase activity reporter gene assay. As a result, MAGT1 was found to be the direct target of miR-199a-5p. The targeted inhibition of MAGT1 induced by miR-199a-5p overexpression led to the immune function depletion of CD8+T cells in HBV patients. Downregulating the expression level of miR-199a-5p could effectively improve the functional depletion of CD8+T cells. These findings indicate that miR-199a-5p and MAGT1 could potentially be used as biomarkers for the diagnosis and treatment of chronic HBV infection.

Reduction and Functional Exhaustion of T Cells in Patients With Coronavirus Disease 2019 (COVID-19).

Background: The outbreak of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has posed great threat to human health. T cells play a critical role in antiviral immunity but their numbers and functional state in COVID-19 patients remain largely unclear. Methods: We retrospectively reviewed the counts of T cells and serum cytokine concentration from data of 522 patients with laboratory-confirmed COVID-19 and 40 healthy controls. In addition, the expression of T cell exhaustion markers were measured in 14 COVID-19 cases. Results: The number of total T cells, CD4+ and CD8+ T cells were dramatically reduced in COVID-19 patients, especially in patients requiring Intensive Care Unit (ICU) care. Counts of total T cells, CD8+ T cells or CD4+ T cells lower than 800, 300, or 400/µL, respectively, were negatively correlated with patient survival. T cell numbers were negatively correlated to serum IL-6, IL-10, and TNF-α concentration, with patients in the disease resolution period showing reduced IL-6, IL-10, and TNF-α concentrations and restored T cell counts. T cells from COVID-19 patients had significantly higher levels of the exhausted marker PD-1. Increasing PD-1 and Tim-3 expression on T cells was seen as patients progressed from prodromal to overtly symptomatic stages. Conclusions: T cell counts are reduced significantly in COVID-19 patients, and the surviving T cells appear functionally exhausted. Non-ICU patients with total T cells counts lower than 800/µL may still require urgent intervention, even in the immediate absence of more severe symptoms due to a high risk for further deterioration in condition.