INF-γ/TGF-β1-primed umbilical cord mesenchymal stem cells boost the T-lymphocytes activity: Modulation of CD25 expression and IL-6 secretion.

Abstract

Background: Mesenchymal stromal/stem cells (MSCs) have potent immunomodulatory abilities, particularly in a milieu of hyperactive immune system, through secreting a number of cytokines, growth factors, bioactive compounds and peptides, and by cell-cell contact. During viral infection, failure of immuno-neutralization of the viral particles, recruits T-lymphocytes (T-cells) that clear the virally-infected cells. MSCs greatly potentiate T-cells anti-viral activity.

Objective: The objective of this study is to assess the ability of the cytokine-primed MSCs to activated T-cells, towards an antiviral application.

Method: Human umbilical cord MSCs (UC-MSCs) were isolated from Wharton Jelly of a consented donor. UC-MSCs were primed with interferon (INF)-γ and transforming growth factor (TGF)-β1. Peripheral blood T-cells were isolated using mini-max and CD3+ population was purified using anti-CD3 immuno-magnetic beads. Naïve or primed MSCs were co-cultured with naïve and phytohemagglutinin (PHA)-activated CD3+ T-cells. T-cell activation was evaluated by changes in their rate of proliferation by cell count, flowcytometric immuno-phenotyping for CD25 expression, and IL-6 secretion in the conditioned medium.

Results: The findings revealed that CD3+ T-cells count nonsignificant differed comparing the five experimental groups; Naïve MSCs, Naïve T cells, coculture with naïve MSCs, coculture with primed MSCs, and upon phytohemagglutinin-activation, despite a nonsignificant reduction of proliferation in the last two groups' coculture. Only the coculture with the primed MSCs showed significant activation of T-cells assessed as CD25 expression compared to the other groups (p < 0.001 and p = 0.002, respectively). The undetectable levels of IL-6 in the conditioned medium of naïve MSCs, turned markedly high after their cytokine-priming (p < 0.001), reaching nonsignificant difference compared to naïve T-cells. Compared to naïve MSCs, naïve T-cells secreted considerable amounts of IL-6 (p < 0.001). Incubation of naïve MSCs with phytohemagglutinin-activated T-cells further the secretion of IL-6, to a level significantly higher than all of the aforementioned three groups; naïve MSCs, naïve T-cells and primed MSCs (p < 0.001, p = 0.0194, and p < 0.001, respectively). However, coculture of the cytokine-primed MSCs with phytohemagglutinin-activated T-cells dampened IL-6 secretion to a level that was significantly lower than that observed with naïve MSCs-phytohemagglutinin-activated T-cells coculture (p < 0.001).

Conclusion: The cytokine-primed UC-MSCs significantly upregulated CD25+ expression on T-cells, while hindering IL-6, without affecting their proliferation rate. This may point to potentially stronger antiviral effects, while alleviating the viral infection-induced cytokine storm.