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Hydrocortisone-modulated Immune Response and Altered Amino Acid Pool in Vitro
Abstract
Background: Dietary deficiencies, from macro- to micronutrients, are often associated with dysfunction of the immune system. The aim for this study was to assess changes in amino acid metabolism and immune response in a modeled stress environment.
Methods: Heparinized blood samples from healthy donors were collected by venipuncture. Peripheral blood mononuclear cells were isolated and then incubated with a mixture of LPS and PHA in RPMI-1640 medium. Cell cultures were treated with hydrocortisone at physiological (10-8 M) and stress (10-6 M) concentrations. Surface expression of CD25 by the CD3+ lymphocytes was analyzed by flow cytometry. Levels of the cytokines IL-2, IFN-gamma, IL-4, and IL-10 were measured with ELISA. Quantification of IL-2- and IFN-gamma- secreting T cells was performed in cell cultures treated with PMA, ionomycin, and brefeldin A.
Results: The number of CD3+CD25+ cells was significantly lower in cultures treated with 10-6 M of hydrocortisone than in control cultures. Treatment of cell cultures with 10-8 M hydrocortisone significantly increased levels of IFN-gamma and IL-10, but not IL-2 and IL-4. Treatment with 10-6 M of hydrocortisone significantly suppressed secretion of all studied cytokines. Treatment with 10-8 M hydrocortisone produced a consistent unidirectional effect on amino acids in the supernatant medium: increased concentrations of almost all amino acids. Treatment with 10-6 M hydrocortisone significantly decreased the level of asparagine while it increased levels of serine and tyrosine compared to control cultures.
Conclusion: Data suggest that the stress-dose of cortisol modulated amino acid metabolism in mitogen-stimulated immunocompetent cells in vitro. Also, observed differences in amino acid concentrations between cultures suggest that supplementation with low doses of endocrine mediators may create a more physiological environment for culturing PBMCs.
J Endocrinol Metab. 2011;1(4):166-173
doi: https://doi.org/10.4021/jem49w