ObjectivesTo explore synergistic effect between angiotensin II receptor blockers (ARBs) and statins on Th17/Treg functional imbalance in hypertensive patients with carotid atherosclerosis. MethodsThis study was a 2×2 factorial randomized, prospective, double-blind, placebo-controlled trial. One hundred and fifty nine hypertensive patients with carotid atherosclerosis were randomized to the administration of control group, telmisartan group, rosuvastatin group, and combination group (telmisartan plus rosuvastatin) base on hydrochlorothiazide treatment. Carotid ultrasonography, parameters of Th17/Treg functional axis, interleukin (IL)-1β, IL-2, interferon (IFN)-γ, hypersensitive C-reactive protein (hsCRP), monocyte chemotactic protein (MCP)-1 were evaluated. ResultsBlood pressure level markedly reduced in four groups. There was significantly synergistic effect of combination of telmisartan with rosuvastatin on reducing carotid imtima-media thickness (IMT), Th17 cells frequency, IL-17, IL-6, IL-23, tumor necrosis factor (TNF)-α, expression of retinoic acid receptor-related orphan receptor (ROR)γt mRNA, Th17/Treg ratio, IL-1β, IL-2, IFN-γ, hsCRP, and MCP-1, and increasing Treg cells frequency, IL-10, transforming growth factor(TGF)-β1, and expression of forkhead/winged helix transcription factor (Foxp3) mRNA (all P<0.05). Change rate of IMT statistical positively related to descent rates of Th17 cells frequency, IL-17, IL-6, IL-23, TNF-α, expression of RORγt mRNA, Th17/Treg ratio, IL-1β, IL-2, IFN-γ, hsCRP, and MCP-1, and negatively related to increased rates of Treg frequency, IL-10, TGF-β1, and expression of Foxp3 mRNA, respectively (all P<0.05). ConclusionThere is a synergistic effect of combination of telmisartan with rosuvastatin on ameliorating Th17/Treg functional imbalance in hypertensive patients with carotid atherosclerosis.