Objective: To investigate the effect of allitridin on murine cytomegalovirus (MCMV) induced regulatory T cells (Treg) amplification in vitro.
Methods: A co-culture system of T cells and MCMV infected mouse embryo fibroblasts (MEF) was established. A maximum tolerance concentration (MTC) of allitridin was added into the co-culture system. After 3 days, the change of Foxp3 mRNA was measured by real-time PCR. And the percentages of Tc1 (CD3(+)CD8(+)IFN-γ(+)), Tc2 (CD3(+)CD8(+)IL-4(+)), Th1 (CD3(+)CD8(-)IFN-γ(+)) and Th2 (CD3(+)CD8(-)IL-4(+)) were analyzed by flow cytometry. The production of IL-10 and TGF-β in supernatants was detected with double-antibody sandwich ELISA while the viral load of culture quantified by plaque assay. All results were compared with those of the placebo group.
Results: The MTC of allitridin was 9.83 µg/ml in MEF. The treatment of 9.83 µg/ml allitridin could partly block the MCMV induction of Foxp3 mRNA expression [(87 ± 5) vs (114 ± 8), P < 0.01]. The percentages of Tc1, Tc2 and Th1 significantly increased to the levels of (12.42 ± 1.23)%, (4.28 ± 0.56)% and (13.25 ± 0.68)% respectively. They showed statistic differences with those of placebo controls [(6.85 ± 0.92)%, (2.34 ± 0.42)% and (9.32 ± 0.86)%; all P < 0.01]. Meanwhile, the levels of IL-10 and TGF-β1 in supernatants also significantly decreased to (29.98 ± 3.15) pg/ml and (3.48 ± 0.23) ng/ml by allitridin treatment as compared with placebo controls [(38.21 ± 4.02) pg/ml and (5.31 ± 0.59) ng/ml, all P < 0.05]. In addition, the MCMV plaque assays showed that allitridin significantly suppressed the viral loads by one order of magnitude.
Conclusion: Allitridin can partly retrieve MCMV-induced Treg expansion and Treg-mediated anti-MCMV immunosuppression so as to enhance the specific cellular immune responses against CMV.