The role of CD4+ T cells in Amyotrophic Lateral Sclerosis

Amyotrophic Lateral Sclerosis is a fatal enigmatic disease with a low prevalence, a survival period of 2-4years, and no cure. There have been various theories and hypotheses trying to discern the etiology of thedisease. However, there has not been a breakthrough. Recently, the clinical role of the adaptive system,particularly CD4+ T cells, in ALS disease has come under scrutiny. CD4+ T cells are a well-studiedgroup of immune cells that vary greatly depending on the subpopulation phenotype that underlies theirfunction. In this review, we cover the recent update on the role of CD4+ T cells in the origin and progressof ALS, and we show that understanding the Th17/Treg axis could prove very important to challengingthis disease. In particular, we update the SWITCH model, which suggests that the initial phase of thedisease progression is mediated by Treg, whereas the later phase is mediated by Th17. We propose thatALS represents complex stages of interaction between proinflammatory and anti-inflammatory cells. Thisrelationship is mediated by the difference in the ability of infiltration of the BBB as well as the brainregion infiltrated and the time of infiltration.