Smoking Leads to More Severe and Difficult to Treat Multiple Sclerosis

As if there aren’t enough reasons to stop smoking, a study has revealed smoking also increases the risk of developing multiple sclerosis.

According to study results presented at the 2015 annual meeting of the American Academy of Neurology in Washington, DC, researchers tied the effects of cigarette smoke with various health issues experienced by current and potential multiple sclerosis (MS) patients. Not only is cigarette smoke associated with an increased risk of developing MS, but it also affects disease progression and treatment.

“In previous studies we demonstrated that Lewis rats exposed to cigarette smoke develop increased brain inflammation and oxidative stress,” lead author Walter Royal III, MD, and colleagues wrote in the presentation. “In these studies we examine the effects of cigarette smoke exposure on systemic and brain inflammatory responses in a murine model of MS, experimental allergic encephalomyelitis (EAE).”

The team analyzed female mice under different conditions by splitting them up into one of the following groups:

• Exposed to the smoke chamber but not cigarette smoke or induced to get EAE
• Exposed to cigarette smoke but not induced to get EAE
• Not exposed to cigarette smoke but induced to get EAE
• Exposed to cigarette smoke and induced to get EAE
• Not exposed to cigarette smoke or the smoking chamber (controlled group)

For the mice that were exposed to cigarette smoke (5 days per week for 4 weeks) the cigarettes contained the “regular” amount of nicotine (0.7 mg per stick and tar (9.4 mg per stick). Also, they were restrained and ventilated by the smoke machine. The mice were immunized with oligodendrocyte glycoprotein peptide fragment after one month of cigarette smoke exposure and after an additional two weeks their brains were removed for further evaluation.

The authors noted that the control group was under the same restraints but without the smoke.

From this examination the team found that in the mice induced to develop EAE, the ones who were also exposed to cigarette smoke had “significantly enhanced pro-inflammatory response, with increased levels of immune cell activation and cytokine secretion.” The smoke was associated with higher oxidative stress, as previous studies have suggested, and lower expression of Nrf2 as well. The researchers pointed out that in the mice with EAE exposed to cigarette smoke, the nuclear translocation of the transcription factor climbed.

“Such effects may contribute to the development of enhanced disease activity among individuals with MS, and, therefore, studies of the mechanisms and potential treatment of these effects are required the authors wrote.

The study authors concluded that cigarette smoke increases the risk of developing the disease while also making it more likely that treatment will fail.