ABSTRACT
BACKGROUND: Flavonoids are naturally occurring compounds, extensively distributed in plants. T helper (Th)1 and Th2 cytokines balance plays an essential role in the reaction of inflammatory, allergic and infectious processes and transplantation rejection. PURPOSE: This systematic review focuses on various classes of flavonoids with a view to evaluate whether Th1/Th2 cytokine-mediated pathways of immunoenhancement could reduce immune overwhelming reactions. METHODS: Articles in English published from inception to December 2017 reporting flavonoids with immunomodulatory activity for the management of immune-mediated disorders were acquired from PubMed, EMBASE, Scopus and Web of Science and a animal experiments where Th1 and Th2 cytokines were investigated to assess the outcome of immunoregulatory therapy were included. CHAPTERS: 1809 publications were identified and 26 were included in this review. Ten articles described the effect of flavonoids on allergic inflammation in an animal model of asthma; eleven in vivo studies evaluated the immunomodulating and immunosuppressive effects of flavonoids on Th1/Th2 cytokines production and five reports described the regulatory role of flavonoids for Th1/Th2 cytokine responses to experimental arthritis and myocarditis. Modulation of Th1/Th2 cytokine balance, inhibition of eosinophil accumulation and remodeling of the airways and lungs, downregulation of Notch and PI3K signaling pathways, regulation of CD4â¯+â¯/CD8â¯+â¯lymphocytes ratio and decreasing inflammatory mediator expressions levels are among the most important immunopharmacological mechanisms for the retrieved flavonoids. CONCLUSION: Naturally occurring flavonoids discussed in the present article have optimal immunomodulation to prevent immune-mediated disorders through management of Th1/Th2 cytokine balance.
Subject(s)
Flavonoids/pharmacology , Immunologic Factors/pharmacology , Th1 Cells/drug effects , Th2 Cells/drug effects , Animals , Asthma/drug therapy , Asthma/immunology , CD4-Positive T-Lymphocytes/drug effects , CD4-Positive T-Lymphocytes/immunology , CD8-Positive T-Lymphocytes/drug effects , Cytokines/metabolism , Disease Models, Animal , Eosinophils/drug effects , Eosinophils/immunology , Hypersensitivity/drug therapy , Hypersensitivity/immunology , Inflammation/drug therapy , Inflammation/metabolism , Lung/drug effects , Lung/immunology , Lung/metabolism , Myocarditis/drug therapy , Myocarditis/immunology , Phosphatidylinositol 3-Kinases/metabolism , Th1 Cells/immunology , Th2 Cells/immunology , Th2 Cells/metabolismABSTRACT
Citrus sinensis (L.) Osbeck is extensively cultivated worldwide and one of the most consumed fruits in the world. We evaluated the therapeutic properties of the methanol extract from Citrus sinensis fruit peel (CSMe) in high-fat diet-fed streptozotocin-induced insulin-resistant diabetic rats. Body weight, food intake, and water consumption were analysed. Biochemical and molecular biologic indices, and the expression of insulin receptor-induced signalling molecules were assessed to identify possible mechanisms. In addition, we conducted histology of pancreatic and adipose tissues. UHPLC-MS/MS analysis showed the presence of 17 dietary phenolics at substantial concentrations. High-fat diet-fed streptozotocin-induced diabetic rats administered CSMe (50 and 100â¯mg/kg) had reduced fasting blood glucose (56.1% and 55.7%, respectively) and plasma insulin levels (22.9% and 32.7%, respectively) compared with untreated diabetic control rats. CSMe reversed the biochemical abnormalities in diabetic rats, showed cytoprotective activity, and increased the intensity of the positive immunoreactions for insulin in pancreatic islets. CSMe treatment increased the expression of PPARγ in the adipose tissue and signalling molecules GLUT4 and insulin receptor. Our data suggest that CSMe could optimize glucose uptake of adipose tissues through the insulin-dependent signalling cascade mechanism and it should be investigated in the management of individuals with type 2 diabetes mellitus.
