Is a chronic autoimmune, inflammatory, and neurodegenerative disease that affects the central nervous system (CNS). MS is characterized by immune dysregulation, which results in the infiltration of the CNS by immune cells, triggering demyelination, axonal damage, and neurodegeneration. Although the exact causes of MS are not fully understood, genetic and environmental factors are thought to control MS onset and progression. In this article, we review the main immunological mechanisms involved in MS pathogenesis.
The Role of T Cells in MS and Immune Dysfunction
White blood cells circulate in the blood and are produced when the immune system perceives a foreign body and instructs the cells to eliminate it, thereby “protecting” the body. To reach the nerves within the CNS, the immune system cells and molecules must cross a protective barrier that surrounds the blood vessels. Known as the blood-brain barrier (BBB), this layer of cells is designed to prevent damaging cells and other substances in the blood (including those that could cause disease) from entering the brain, optic nerves, and spinal cord of the CNS.
With MS, damaging immune-system cells (macrophages and other lymphocytes) can break through the BBB and enter the CNS, where they begin their attack on the myelin. This creates inflammation along the nerves where the myelin is being damaged. Areas of activity are known as lesions (or plaques). Lesions vary in activity levels, ranging from very active (acute), to chronic, to inactive. If MS is an autoimmune disease, some unidentified factor has caused the immune system to become activated and misdirected. Such a cause is still a mystery, although evidence grows to support several different possible theories. A complex genetic predisposition appears to be involved, with a slightly increased risk for close family members.
Environmental factors also come into play. Among others, these include how far a person lives from the equator and one’s lack of exposure to vitamin D (naturally derived from sunlight and certain foods); cigarette smoking, pollutants, and other toxins; various diets, including a high intake of saturated fats and/or a low intake of fish oils; as well as viral or bacterial infections. About viral infections, the Epstein-Barr Virus (EBV) appears to have the most evidence as a possible trigger for MS.
When activated, the CD4+ cells differentiate, or mature into four different subsets of T cells: Th1 cells are pro-inflammatory, Th3 cells are anti-inflammatory, Th17 cells are pro-inflammatory, T-regs are regulatory; they can suppress the function of pro-inflammatory T cells; In this manner, T-regs help to protect against autoimmune disorders.
Cell immunotherapy with Regulatory T lymphocytes is a therapeutic option to inactivate and suppress activated T lymphocytes and prevent neuronal deterioration from continuing.
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