Low sensitivity to glucocorticoid inhibition of in vitro Th17-related cytokine production in multiple sclerosis patients is related to elevated plasma lipopolysaccharide levels

Exogenous glucocorticoid plays an important role in controlling clinical relapses of multiple sclerosis (MS), but the response to this treatment differs among patients. In this study, T-cell proliferation and IL-17 production were less sensitive to hydrocortisone (HC) inhibition in MS patients than healthy individuals, mainly in CD8+ compartment. Furthermore, in vitro IL-17 production was positively related with neurological disability and its release was proportional to IL-23 and IL-6 productions by LPS-activated monocytes. Interestingly, elevated LPS levels were quantified in the plasma of MS patients, and their levels were directly related to in vivo IL-6 production. Finally, HC-resistance in reducing IL-17 production by polyclonally-activated CD8+ T cells was particularly observed among MS patients with higher in vivo LPS levels. In summary, the results indicate that T-cells derived from MS patients show an enhanced Th17-like phenotype that is directly associated with neurological disability, resistance to glucocorticoid inhibition and elevated bacterial translocation.