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Smoking worsens multiple sclerosis prognosis: Two different pathways are involved

Jorge Correale, Mauricio F. Farez

Journal of Neuroimmunology, Volume 281, 15 April 2015, Pages 23-34


  • Smoking is a risk factor for early conversion to clinically definite MS.
  • Disease progression is more rapid in smoker MS patients compared to non-smokers.
  • Indoleamine 2,3-dioxygenase activity is reduced in MS patients who smoke.
  • Activity of renin–angiotensin system is increased in MS patients who smoke.
  • Smoking led to increased number of IL-6, IL-13, IL-17 and IL-22 producing cells.


Smoking worsens multiple sclerosis (MS) prognosis. Our study provides evidence that indoleamine 2,3-dioxygenase activity is reduced in MS patients who smoke, leading to increased production of IL-6 and IL-13. Additionally, both degree of expression and renin–angiotensin system activity levels were increased in MS patients who smoked, inducing increase in IL-17 and IL-22-producing cell numbers as well as significantly greater production of CCL2, CCL3 and CXCL10 chemokines by monocytes. Finally, both pathways contributed to a significant decrease in the number of CD4+CD25+FoxP3 + regulatory T cells in MS patients who smoked. Both pathways could be responsible for the association between smoking and MS risk.

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About the Editors

  • Prof Timothy Vartanian

    Timothy Vartanian, Professor at the Brain and Mind Research Institute and the Department of Neurology, Weill Cornell Medical College, Cornell...
  • Dr Claire S. Riley

    Claire S. Riley, MD is an assistant attending neurologist and assistant professor of neurology in the Neurological Institute, Columbia University,...
  • Dr Rebecca Farber

    Rebecca Farber, MD is an attending neurologist and assistant professor of neurology at the Neurological Institute, Columbia University, in New...

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