The use of alpha 1 thymosin as an immunomodulator of the response against SARS-Cov2.

In vitro study examining the immunomodulatory effects of Thymosin-alpha-1 on dendritic cells and T cells in the context of SARS-CoV2 infection.

“Our study aims to further in vitro effect of human Thymosin-alpha-1 (α1Thy) treatment on the immune system in population groups with different thymic function levels in the scenario of SARS-CoV2 infection.”

Asymptomatic subjects who had previously been diagnosed with SARS-CoV2, divided into two age groups: younger than 40 years and older than 65 years.

“Donors from Hospital General Universitario Gregorio Marañón (Madrid, Spain) and Hospital Residencia de la Caridad (Sevilla, Spain) were recruited following these inclusion criteria: 1) Asymptomatic subjects diagnosed during the last 18 months with SARS-CoV2 by RT-PCR + or SARS-CoV2 anti-IgM/IgG + test, younger than 40 years-old (n = 18); 2) Asymptomatic subjects diagnosed during the last 18 months with SARS-CoV2 by positive RT-PCR + or SARS-CoV2 anti-IgM/IgG + test older than 65 years-old (n = 16).”

32 participants total, consisting of 18 individuals under 40 years old and 16 individuals over 65 years old.

“Participants' peripheral blood mononuclear cells (PBMCs) were separated from peripheral blood samples (30 ml) collected from participants (n = 32) in ethylenediaminetetraacetic acid (EDTA) tubes using Ficoll (Ficoll- PaqueTM PLUS) by density gradient centrifugation on the day of blood collection and used immediately for the isolation of DCs, CD4 + and CD8 + T lymphocytes (TLs).”

The in vitro co-culture experiments were conducted for 6 hours.

“For the in vitro co-culture system, after DCs stimulation, autologous CD4 + or CD8 + TLs were added to the α1Thy-stimulated or unstimulated DCs conditions at a DC:TL ratio of 50.000:150.000 for 6 h with 1 µg/ml anti-CD28/CD49d, 0.7 µg/ml monensin (BD Biosciences) and 10 µg/ml brefeldin A (Biolegend) at 37 °C/5% CO2 in the presence or absence of 6 nmoles/peptide of a PepTivator® SARS-CoV-2 Select—premium grade (Miltenyi).”

Thymosin-alpha-1 upregulated activation markers (CD40, CD80, TIM-3) and increased TNFα production in dendritic cells, particularly in plasmacytoid dendritic cells.

“Activation markers such as CD40, CD80 and TIM-3 were upregulated in α1Thy presence, especially in plasmacytoid dendritic cells (pDCs) and, with increased TNFα production was observed compared to untreated condition.”

Co-culturing T cells with α1Thy-treated dendritic cells resulted in decreased production of proinflammatory cytokines (TNFα, IFNγ, IL-2) in response to SARS-CoV2 peptides.

“Co-cultures of CD4 + and CD8 + T cells with DCs treated with α1Thy in response to SARS-CoV2 peptides showed a decrease in the cytokine production compared to the condition without α1Thy pre-treated.”

The polyfunctionality of SARS-CoV2-specific T cells was maintained in the presence of α1Thy, despite the reduction in proinflammatory cytokine production.

“Finally, the polyfunctionality measured in SARS-CoV2 Specific-T cells response was maintained in α1Thy presence in total and memory subpopulations CD4 + and CD8 + T-cells, despite decreased proinflammatory cytokines production.”

The study had small sample sizes and lacked control groups of vaccinated individuals who had not undergone SARS-CoV2 infection.

“This study has some limitations such the size of the study groups. We did not have control groups (< 40 years and > 65 years) that despite vaccination had not undergone SARS-CoV2 infection, which means that we do not have data on the effect of α1Thy in healthy donors without SARS-CoV2 infection.”