Exploring the Effect and Underlying Mechanism of Rosmarinic Acid on Autoimmune Thyroiditis in Rats Based on the PI3K/Akt Pathway
Objective To investigate the effect and underlying mechanism of rosmarinic acid on autoimmune thyroiditis(AIT)in rats based on the phosphoinositide 3-kinase(PI3K)/protein kinase B(AKT)pathway.Methods A rat model of AIT was established by feeding high iodine water combined with subcutaneous injection of thyroglobulin and Freund's adjuvant.The study rats were randomly grouped into four groups:model group,low-dose rosmarinic acid(20mg/kg)group,high-dose rosmarinic acid(40mg/kg)group,and high-dose rosmarinic acid(40mg/kg)+IGF-1(PI3K/Akt activator,0.75μg/kg)group,with 10 rats in each group.Another 10 SD rats were selected as the control group:fed with normal water and subcutaneously injected with equivalent doses of physiological saline.After treated with rosmarinic acid and IGF-1,ELISA were applied to measure levels of serum thyroid peroxidase antibody(TPOAb)and anti-thyroid autoantibodies(TGAb)in rats;HE staining was applied to detect pathological damage in the thyroid tissue of rats in each group;Immunohistochemical staining was applied to detect the expression of CD45R in the thyroid tissue of rats in each group;TUNEL staining was applied to detect the apoptosis of thyroid cells in rats of each group;ELISA was applied to measure levels of inflammatory related factors,such as γ-interferon(IFN-γ),interleukin-4(IL-4),IL-17,and IL-10 secreted by Th cells in rat serum;Immunoblotting experiments were applied to detect the expression of PI3K/Akt pathway related proteins in the thyroid tissue of rats in each group.Results Compared with the control group,levels of TGAb,TPOAb,IFN-γ,and IL-17,pathological injury score,CD45R relative positive expression,thyroid cell apoptosis rate,p-PI3K/PI3K,and p-AKT/Akt in the model group were significantly increased(P＜0.05),while levels of IL-4 and IL-10 were significantly decreased(P＜0.05);Compared with the model group,levels of TGAb,TPOAb,IFN-γ,and IL-17,pathological injury score,CD45R relative positive expression,thyroid cell apoptosis rate,p-PI3K/PI3K,p-AKT/Akt in the low-dose and high-dose rosmarinic acid groups were all reduced(P＜0.05),while levels of IL-4 and IL-10 were increased(P＜0.05);Compared with the low-dose rosmarinic acid group,levels of TGAb,TPOAb,IFN-γ,and IL-17,pathological injury score,CD45R relative positive expression,thyroid cell apoptosis rate,p-PI3K/PI3K,p-AKT/Akt in the high-dose rosmarinic acid group were all reduced(P＜0.05),while levels of IL-4 and IL-10 were increased(P＜0.05),and high-dose rosmarinic acid had a stronger effect;IGF-1 could weaken the effect of rosmarinic acid on AIT rats.Conclusion Rosmarinic acid can regulate Th cytokine secretion by blocking the activation of the PI3K/Akt pathway,thereby inhibiting immune inflammatory response,reducing lymphocyte infiltration and apoptosis in thyroid tissue,and improving symptoms in AIT rats.
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