Immunological aspects of autoimmune thyroid disease - Complex interplay between cells and cytokines

Autoimmune thyroid disease (ATD) is a chronic autoimmune thyroiditis with a complex pathogenesis including environmental factors, genetic background and immune system actions. Despite the large-scale research and discovery of new subpopulations of lymphocytes, cytokines, chemokines and their functions in the human body, the ethiology of ATD in many aspects remains a mystery. This article tries to summarize mostly the immunological aspects of this disease, including the roles of different cells types (dendritic cells, B cells, CD4⁺ and CD8⁺ T cells, NK cells and regulatory T cells) and of different cytokines (secreted by Th1/Th2/Th17/Th22 lymphocyte subpopulations and other, including the IL-23 and CXCL10). We describe the role of immunological abnormalities in the ATD pathogenesis and show that for some cells and cytokines their respective roles are not clear, and bi-directional action is possible. Finally, we propose a network of interactions between the immune cells and thyrocytes in the course of ATD.