The role of thyroid hormone in the renal immune microenvironment

Thyroid hormones are essential for proper kidney growth and development. The kidney is not only the organ of thyroid hormone metabolism but also the target organ of thyroid hormone. Kidney disease is a common type of kidney damage, mainly including different types of acute kidney injury, chronic kidney disease, diabetic nephropathy, lupus nephritis, and renal cell carcinoma. The kidney is often damaged by an immune response directed against its antigens or a systemic immune response. A variety of immune cells in the innate and adaptive immune systems, including neutrophils, macrophages, dendritic cells, T lymphocytes, and B lymphocytes, is essential for maintaining immune homeostasis and preventing autoimmune kidney disease. Recent studies have found that thyroid hormone plays an indispensable role in the immune microenvironment of various kidney diseases. Thyroid hormones regulate the activity of neutrophils, and dendritic cells express triiodothyronine receptors. Compared to hypothyroidism, hyperthyroidism has a greater effect on neutrophils. Furthermore, in adaptive immune systems, thyroid hormone may activate T lymphocytes through several underlying mechanisms, such as mediating NF-κB, protein kinase C signalling pathways, and β-adrenergic receptors, leading to increased T lymphocyte activation. The present review discusses the effects of thyroid hormone metabolism regulation in the immune microenvironment on the function of various immune cells, especially neutrophils, macrophages, dendritic cells, T lymphocytes, and B lymphocytes. Although there are not enough data at this stage to conclude the clinical relevance of these findings, thyroid hormone metabolism may influence autoimmune kidney disease by regulating the renal immune microenvironment.