Objective: To investigate the role of the helper T cells (Th) 17/Treg cell imbalance on the development of atherogenesis in apo E knockout mice.
Methods: Apo E(-/-) mice were examined at age of 6, 12, 24 and 48 weeks (n = 10 each). Age matched C57/B6 mice served as controls. The number of Th17, Treg and dendritic cell (DC) was detected by flow cytometry. The levels of interleukin(IL)-6, IL-17A and transforming growth factor(TGF)-β1 were detected by ELISA. The suppression ability of Treg was evaluated by mixed lymphocyte reaction.
Results: With increasing ages, the frequencies of Th17 and Treg in CD4(+) T cells were increased (Th17 ratio from 1.00% to 3.14%; Treg ratio from 8.08% to 27.80%) and the level of IL-17A was up-regulated [from (87 ± 15) pg/ml to (191 ± 26) pg/ml], but the rate of Th17/Treg cell and the level of TGF-β1 remained stable during atherogenesis in apo E knockout mice. Furthermore, the phenotype of splenic DC was matured and the blood level of IL-6 was up-regulated [from (43 ± 5) pg/ml to (104 ± 11) pg/ml] with aging in apo E(-/-) mice. Addition of IL-6 to T cells reversed the ability of Treg to suppress the proliferation of effective T cells.
Conclusion: DC overactivation, subsequent increased secretion of IL-6, inhibition of Treg cell function and the Th17/Treg cell imbalance play key roles on the atherogenesis in apo E(-/-) mice.