Multiple Sclerosis: Role of Cells. Biological & Biomedical Sciences

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Role of Cells in Multiple Sclerosis
Multiple sclerosis is triggered based on different physiological and environmental factors. However, one notable aspect of MS is that lesion which is formed on the surface of neurons disrupts the blood brain barrier (BBB), which serves the function of separating blood from the neurons. With the disruption of BBB, the endothelium becomes permeable leading to passing of MS tolerable cells such as T cells, B cells and NK cells that promote progression of the disease.
T cells
The T cells have been identified as the greatest contributing factor in the progression and onset of MS. Høglund and Maghazachi indicated that various experiments conducted on animals have found a close link between MS and T cells. The association largely originates from the role that the T cells play in the body and in relation to HLA class II genes. Early research and experimental autoimmune encephalomyelitis (EAE ) conducted on rodents suggested CD4+ T cells secreting interferon-gamma (IFN-γ) were the main mediators in the progression of MS. However, recent research has found other forms of T cells that also contribute to the progression of MS. One of such cells is the T helper 17 (Th17) cell that secretes inflammatory cytokines IL-17, IL-6 and is regulated by IL-23. When these cells are deregulated it leads to inflammation (Correale et. al 528-529)..
Various studies on MS patients indicated an overwhelming presence of CD4+ cells which secrete IL-17 in active lesions (Høglund & Maghazachi). Notably, in MS patients, both CD4+ and CD8+ cells express IL-17. Once secreted, the Th17 cells are then transported through choroid into the cerebrospinal fluid (CSF). The cells may also produce Granulocyte Macrophage Colony-Stimulating Factor (GM-CSF), which in return produces an IL-23, which furthers spread of the disease. Also, the Th17 cells affect the BBB, which serves the function of separating blood from the neurons. The disruption is facilitated by increasing permeability of the neurons’ endothelium due to the secretion of IL-17 and IL-23. ...