Compared with females, male Dark Agouti (DA) rats immunized for experimental autoimmune encephalomyelitis (EAE) with rat spinal cord homogenate in complete Freund's adjuvant (CFA) exhibited lower incidence of the disease, but the maximal neurological deficit was greater in the animals that developed the disease. Consistently, at the peak of the disease greater number of reactivated CD4+CD134+CD45RC- T lymphocytes was retrieved from male rat spinal cord. Their microglia/macrophages were more activated and produced greater amount of prototypic proinflammatory cytokines in vitro. Additionally, oppositely to the expression of mRNAs for IL-12/p35, IL-10 and IL-27/p28, the expression of mRNA for IL-23/p19 was upregulated in male rat spinal cord mononuclear cells. Consequently, the IL-17+:IFN-γ+ cell ratio within T lymphocytes from their spinal cord was skewed towards IL-17+ cells. Within this subpopulation, the IL-17+IFN-γ+:IL-17+IL-10+ cell ratio was shifted towards IL-17+IFN-γ+ cells, which have prominent tissue damaging capacity. This was associated with an upregulated expression of mRNAs for IL-1β and IL-6, but downregulated TGF-β mRNA expression in male rat spinal cord mononuclear cells. The enhanced GM-CSF mRNA expression in these cells supported the greater pathogenicity of IL-17+ T lymphocytes infiltrating male spinal cord. In the inductive phase of the disease, contrary to the draining lymph node, in the spinal cord the frequency of CD134+ cells among CD4+ T lymphocytes and the frequency of IL-17+ cells among T lymphocytes were greater in male than in female rats. This most likely reflected an enhanced transmigration of mononuclear cells into the spinal cord (judging by the lesser spinal cord CXCL12 mRNA expression), the greater frequency of activated microglia/macrophages and the increased expression of mRNAs for Th17 polarizing cytokines in male rat spinal cord mononuclear cells. Collectively, the results showed cellular and molecular mechanisms underlying the target organ specific sexual dimorphism in the T lymphocyte-dependent immune/inflammatory response, and suggested a substantial role for the target organ in shaping the sexually dimorphic clinical outcome of EAE.
There has been some interest in the use sex hormones to treat autoimmunity or progressive MS and indeed there is a lot of evidence that oestrogens can inhibit immune-mediated disease, there is data that testosterones can inhibit disease. However, likewise there is data indicating that it can go the other way and it may not be a simple relationship.
This study suggests that maleness can be associated with worse autoimmunity and imply that the CNS is involved in this. Although as it is EAE I think many of you won't be interested but this simply serves a warning that results with sex hormones may not be a straight answer. It may also be different for progression mechanisms as compared to immune mechanisms. The studies in humans have not yet finished and so be warned about off-label use and use them, if you use them, with your "eyes wide-open".