Regulatory T Cells Decreased during Recovery from Mild COVID-19

Purilap Seepathomnarong; Jomkwan Ongarj; Ratchanon Sophonmanee; Bunya Seeyankem; Sarunyou Chusri; Smonrapat Surasombatpattana; Nawamin Pinpathomrat

doi:10.3390/v14081688

Regulatory T Cells Decreased during Recovery from Mild COVID-19

Viruses. 2022 Jul 30;14(8):1688. doi: 10.3390/v14081688.

Authors

Purilap Seepathomnarong¹, Jomkwan Ongarj¹, Ratchanon Sophonmanee¹, Bunya Seeyankem¹, Sarunyou Chusri², Smonrapat Surasombatpattana³, Nawamin Pinpathomrat¹

Affiliations

¹ Department of Biomedical Sciences and Biomedical Engineering, Faculty of Medicine, Prince of Songkla University, Songkhla 90110, Thailand.
² Department of Internal Medicine, Faculty of Medicine, Prince of Songkla University, Songkhla 90110, Thailand.
³ Department of Pathology, Faculty of Medicine, Prince of Songkla University, Songkhla 90110, Thailand.

Abstract

Depending on the intensity and duration of SARS-CoV-2 infection, the host immune response plays a significant role in immunological protection. Here, we studied the regulatory T-cell (Treg) response in relation to kinetic change and cytokine production in patients with mild COVID-19. Nineteen SARS-CoV-2-positive patients were recruited, and blood was collected at four time points, i.e., seven days after admission, after discharge, and one and three months after recovery. CD3⁺CD4⁺CD25⁺CD127^low was marked as the Treg population, with IL-10 and TGF-β used to study cytokine-producing Tregs. IFN-γ-producing CD8⁺ T cells were observed for an effector response. The Treg percentage in patients with mild COVID-19 increased during hospitalization compared to during the recovery period. Peripheral blood mononuclear cells (PBMCs) were quantified, and the T-cell response was characterized by re-stimulation with S1 and N peptides. IL-10 and TGF-β were produced by CD25⁺CD127^low T cells during the active infection phase, especially with N peptide stimulation. Compared to N peptide stimulation, S1 peptide stimulation provided superior IFN-γ-secreting CD8⁺ T-cell responses. Our results suggest that while IFN-γ⁺CD8⁺ T cells confer antiviral immunity, cytokine-producing Tregs may have a substantial role in regulating inflammatory responses in mild SARS-CoV-2 infection. Novel vaccine development may also consider enhancing T-cell repertoires.

Keywords: COVID-19; PMBC; SARS-CoV-2; cytokine production; immune response; inflammatory response; regulatory T cells; viral peptides.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

CD8-Positive T-Lymphocytes
COVID-19*
Cytokines
Humans
Interleukin-10
Leukocytes, Mononuclear
SARS-CoV-2
T-Lymphocytes, Regulatory*
Transforming Growth Factor beta

Substances

Cytokines
Transforming Growth Factor beta
Interleukin-10

Grants and funding

This project was funded by the Medical Science Research and Innovation Institute under the authority of the Research and Development Office (RDO) of Prince of Songkla University, the Thailand Science Research and Innovation (TSRI), and the National Research Council of Thailand (NRCT). The graduate scholarship was awarded by the Faculty of Medicine, Prince of Songkla University. The funding organizations had no role in the design of the study, data collection and analysis, decision to publish, or preparation of the manuscript.