Fig. 1. The Risk factors for Multiple Sclerosis. MS is considered a multifactorial disease with several associated risk factors (e.g., genetics, immunologic factors, insufficient vitamin D, environment).

The underlying cause of pathological changes (e.g., white matter lesions, ocular findings) in MS is still unknown. Several hypotheses propose that chronic inflammation, degeneration, and demyelination of axons are mediated by T-lymphocytes mistakenly targeting components of the CNS as if they were foreign pathogens [1]. Activated T cells cross the blood-brain barrier and recognize self-antigen presented by antigen-presenting cells (APCs) within the CNS. Subsequently, proinflammatory cytokines (e.g., tumour necrosis factor-alpha, interferon-gamma) may be triggered to promote the recruitment of additional immune cells and contribute to the positive feedback loop inflammatory process. Image is under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) License (https://creativecommons.org/licenses/by-nc-nd/4.0/legalcode).