Objective: Graves' disease is an organ-specific autoimmune disease with unknown etiology. TSHR Ab plays the most important role for the pathogenesis of Graves' disease. Recently, the role of cytokines for the pathogenesis of Graves' disease has been studied extensively. Royal jelly (RJ) is a creamy product secreted by young nurse worker bees (Apis mellifera), and it is synthesized in the hypopharyngeal and mandibular glands. RJ has been reported to have such pharmacological characteristics as antitumor, antibacterial, antihypercholesterolemic, antiallergic, antiinflammatory, and immunomodulatory properties. The major aim of the present study is to evaluate the effect of RJ on autoimmunity in peripheral lymphocyte culture and to establish the therapeutic doses.
Research design and methods: In the first phase, lymphocyte cell isolation from four voluntary healthy subjects was performed to find the effective concentration of RJ on immunity. Serial dilutions of the RJ were prepared (0-5 mg/mL). All isolated lymphocyte cells were treated with the above diluted samples. MTT test was carried out after incubation of 72 h. In the second phase, six patients with Graves' disease, newly diagnosed by clinical and laboratory methods and admitted to my hospital and untreated were identified. RJ samples of 0 and 4 mg/mL were incubated in a culture medium for 72 h with isolated lymphocytes obtained from the patients. After incubation, MTT test in lymphocyte cell culture, Th1 cytokines IFN-gamma, TNF-alpha, and IL-12, and Th2 cytokines IL-4 and IL-10 levels by the enzyme amplified sensitivity immunoassay (EASIA) method and TSHR Ab by the radioreceptor method were determined.
Results: The concentration causing lymphocytes to proliferate was found to be 4 mg/mL by MTT test after incubation of 72 h in cell culture medium. Of the cytokines produced and secreted from lymphocytes, IFN-gamma increased, whereas, other cytokines decreased in RJ concentration of 4 mg/mL. Significant differences were found only for IFN-gamma and TNF-alpha. IL-4 concentrations were kept near the level of significancy. Of Th1/Th2 ratios, IFN-gamma/IL-4 and IFN-gamma/IL-10 ratios also exhibited significant differences between 0 and 4 mg/mL. RJ treatment in lymphocytes from patients with Graves' disease shifted the Th1/Th2 cytokine ratio to the side of Th1 cytokine. Therefore, RJ using the treatment and establishing a remission of Graves' disease may be effective as an antithyroid drug treatment. TSHR Ab levels of lymphocyte cell culture supernatants treated with RJ showed significant decreases. Also, the result may suggest that RJ may exert an effect similar to an antithyroid drug for decreasing TSHR Ab levels.
Conclusions: RJ may be effective as an immunomodulatory agent in Graves' disease.