The Repeated Administration of Resveratrol Has Measurable Effects on Circulating T-Cell Subsets in Humans

Abstract

Preclinical studies have shown that resveratrol exerts immunomodulatory effects with potential clinical value in the amelioration of autoimmune disorders and cancer prevention; however, little is known about the in vivo effects of this naturally occurring polyphenol on human immune cells. We assessed the effects of repeated doses of resveratrol (1000 mg/day for 28 days) on circulating immune cells in healthy Japanese individuals. Resveratrol was safe and well tolerated and was associated with significant increases in the numbers of circulating γδ T cells and regulatory T cells and resulted in small, yet significant, decreases in the plasma levels of the proinflammatory cytokines TNF-α and MCP-1 and a significant increase in the plasma antioxidant activity compared with the corresponding antioxidant baseline activity and with that in four control individuals. In in vitro studies, resveratrol significantly improved the growth of γδ T cells and regulatory T cells. These findings demonstrate that resveratrol has some clear biological effects on human circulating immune cells. Further studies are necessary to interpret the long-term immunological changes associated with resveratrol treatment.

Figure 1

Pharmacokinetic studies and the parameters of plasma oxidative stress. (a) The plasma levels of resveratrol in samples collected at baseline and after two and four weeks of resveratrol consumption. (b) The total antioxidant activity (TAA) in plasma from healthy individuals measured at baseline and at after two (W2) and four weeks (W4) of study entry. Data is expressed as mean ± standard error. ∗ indicates statistical significance. (c) The urinary 8-OHdG levels, adjusted by the creatinine concentration correction method, in four individuals at baseline and after two weeks of resveratrol administration.

Figure 2

The effects of resveratrol on circulating immune cells (a) PBMCs from blood samples collected at baseline or at the indicated time (weeks) were analyzed by flow cytometry. The percentage of CD3⁺CD4⁺CD25⁺CD127⁻ circulating Treg cells (a), CD3⁺NKG2D⁺γδ T cells (b), CD3⁺CD56⁺NKG2D⁺ NK cells (c), CD3⁺CD8⁺ T cells (d), CD3⁺CD4⁺ T cells (e), and CD19⁺ B cells (f) are shown. The figures indicate the mean ± SD fold change at the indicated time point. ^∗p < 0.05.

Figure 3

The plasma expression of relevant cytokines and chemokines. The cytokine levels of plasma samples collected at 2, 4, and 6 weeks after study entry were measured using a multiplex cytokine assay. The fold changes of TNF-α (a), MCP-1 (b), CXCL10 (c), and IL-1Ra (d) are shown. ^∗p < 0.05.

Figure 4

The effects of resveratrol on the in vitro proliferation of human γδ T cells. PBMCs from healthy donors were cultured for seven days in T-cell medium stimulated with HMBPP in the presence of the indicated concentrations of resveratrol. The percentage of CD3⁺γδ T cells was determined by flow cytometry. (a) A representative flow cytometry result showing cells cultured with HMBPP alone (control) or with HMBPP together with resveratrol (resv). (b) A summary of the flow cytometry data showing the percentage of γδ T cells derived from three healthy individuals. (c) PBMCs from two healthy donors were cultured with HMBPP as a positive control or with various concentrations of resveratrol (resv) but without HMBPP. The percentage of γδ T cells was assessed in the same manner as (a). ^∗p < 0.05.

Figure 5

The effects of resveratrol on the in vitro proliferation of human Treg cells. PBMCs from healthy donors were cultured for seven days in T-cell medium stimulated with anti-CD3/CD28 beads to activate TCR in the presence of the indicated concentrations of resveratrol. (a) A representative flow cytometry result showing the percentage of CD3⁺CD4⁺CD25⁺CD127⁻ cTreg cells. (b) A summary of the flow cytometry data showing the percentage of CD3⁺CD4⁺CD25⁺CD127⁻ cTreg cells derived from three healthy individuals. (c) PBMCs from two healthy donors were cultured with anti-CD3/CD28 beads as positive control or with various concentrations of resveratrol (resv) but without anti-CD3/CD28 beads. The percentage of CD3⁺CD4⁺CD25⁺CD127⁻ cTreg cells was assessed in the same manner as (a). (d) PBMCs from three healthy donors were cultured for seven days in T-cell medium stimulated with anti-CD3/CD28 beads in the presence of the indicated concentrations of resveratrol. Flow cytometry analysis was performed to enumerate the percentage of Treg cells, which were gated as live⁺CD3⁺CD4⁺Foxp3⁺Treg cells. A representative flow cytometry result is shown. (e) A summary of the flow cytometry data showing the percentage of CD3⁺CD4⁺Foxp3⁺Treg cells derived from three healthy individuals. ^∗p < 0.05.