Insights into the mechanisms of Th17 differentiation and the Yin-Yang of Th17 cells in human diseases.

Th17 cells are a lineage of CD4+ T helper cells with Th17-specific transcription factors RORγt and RoRα. Since its discovery in 2005, research on Th17 has been in rapid progress, and increasing cytokines or transcription factors have been uncovered in the activation and differentiation of Th17 cells. Furthermore, growing evidence proves there are two different subsets of Th17 cells, namely non-pathogenic Th17 (non-pTh17) and pathogenic Th17 (pTh17), both of which play important roles in adaptive immunity, especially in host defenses, autoimmune diseases, and cancer. In this review, we summarize and discuss the mechanisms of Th17 cells differentiation, and their roles in immunity and diseases.

D-dimer surge and coagulation disorders in COVID-19 related pneumonia patients with cardiac injury: A case series.

BACKGROUND: Cardiac injury and coagulation disorders have been two increasing concerns in the management of patients with severe coronavirus disease (COVID-19). Coagulation disorders in COVID-19 patients with cardiac injury have not been characterized. METHODS: We analyzed the data of five COVID-19 patients with cardiac injury who had D-dimer surge (defined as a rapid increase in the D-dimer level in 72 h, from <5-21 µg/mL) during hospitalization, which were extracted from a registered retrospective study (ChiCTR2000031301). Clinical data and data on changes in coagulation parameters were collected, verified, and characterized. RESULTS: Among these five patients, four had pre-existing cardiovascular or cerebrovascular diseases. D-dimer surge was accompanied with prolonged prothrombin time (PT) and reduced platelet count (PLT) and fibrinogen level. Three patients had an ISTH DIC score of 5 and met the criteria for overt DIC. All five patients needed invasive ventilation support and were incubated 0 to 6 days after the first D-dimer upper reference limit (URL) was reached. All five patients died within 10 days after the first D-dimer URL was reached. All five patients had observed D-dimer URL results 1 to 3 days before death. CONCLUSION: D-dimer surge in COVID-19 patients with cardiac injury surely leads to worse in-hospital outcome. D-dimer surge and concomitant DIC can be the leading causes of in-hospital death. Pre-existing cardiovascular or cerebrovascular diseases might pose a higher risk for developing these coagulation disorders. These findings can serve as hypothesis generating and need further clinical trials to confirm.