Thymosin Alpha 1 Reduces the Mortality of Severe Coronavirus Disease 2019 by Restoration of Lymphocytopenia and Reversion of Exhausted T Cells
Open Access
- 22 May 2020
- journal article
- research article
- Published by Oxford University Press (OUP) in Clinical Infectious Diseases
- Vol. 71 (16), 2150-2157
- https://doi.org/10.1093/cid/ciaa630
Abstract
We previously reported that lymphocytopenia and T cell exhaustion is notable in acute COVID19 patients, especially in aged and severe cases. Thymosin alpha 1 (Tα1) had been used in the treatment of viral infections as an immune response modifier for many years. However, clinical benefits and mechanism of Tα1 supplement to COVID-19 are still unclear. We retrospectively reviewed the clinical outcomes of 76 severe cases with COVID-19 admitted into two hospitals in Wuhan from December 2019 to March 2020. The thymus output in peripheral blood mononuclear cells (PBMCs) from COVID-19 patients was measured by T cell receptor excision circles (TREC). The levels of T cell exhaustion markers PD-1 and Tim-3 on CD8+ T cells were detected by flow cytometry. Compared with untreated group, Tα1 treatment significantly reduces mortality of severe COVID-19 patients (11.11% vs. 30.00%, p=0.044). Tα1 timely enhances blood T cell numbers in COVID-19 patients with severe lymphocytopenia (the counts of CD8+ T cells or CD4+ T cells in circulation lower than 400/μL or 650/μL, respectively). Under such conditions, Tα1 also successfully restores CD8+ and CD4+ T cell numbers in aged patients. Meanwhile, Tα1 reduces PD-1 and Tim-3 expression on CD8+ T cells from severe COVID-19 patients in comparison with untreated cases. It is of note that restoration of lymphocytopenia and acute exhaustion of T cells are roughly parallel to the rise of TRECs. Tα1 supplement significantly reduce mortality of severe COVID-19 patients. COVID-19 patients with the counts of CD8+ T cells or CD4+ T cells in circulation lower than 400/μL or 650/μL, respectively, gain more benefits from Tα1. Tα1 reverses T cell exhaustion and recovers immune reconstitution through promoting thymus output during SARS-CoV-2 infection.Keywords
Funding Information
- National Natural Science Foundation of China (81971478, 8177169)
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