Nicotine may protect against the development of multiple sclerosis, according to researchers from the Institute of Environmental Medicine at the Karolinska Institutet in Sweden. In looking for possible causes and risk factors involved in developing MS, a group of researchers in Sweden have examined several possibilities, including smoking and nicotine use.
In a recent study published online, ahead of print, in the journal Multiple Sclerosis, researchers aimed to investigate the influence of moist snuff use on the risk of developing MS while taking smoking habits into consideration (HedstrÃ¶m, 2013). A prior study conducted at the Karolinska Institutet indicated that exposure to environmental tobacco smoke is associated with increased MS risk (HedstrÃ¶m, 2011). The same research group had determined that smoking, but not the use of Swedish snuff, increased the risk of MS (HedstrÃ¶m, 2009).
What does snuff and tobacco smoke have in common? Nicotine.
Nicotine has been reported to have an effect on the immune system by regulating cytokine release (CloÃ«z-Tayarani, 2007). Cytokines are proteins which help to control inflammatory responses in the body. Types of cytokines include interleukins, lymphokines (produced by lymphocytes), and monokines. When nicotine receptors on these immune cells are activated, it has an anti-inflammatory effect.
However, despite its reported anti-inflammatory properties, nicotine is associated with the development of specific diseases such as respiratory tract infections, chronic airway disease, asthma, allergies, and lung cancers. This is most likely because nicotine has an inhibitory effect on TNF, IL-1Î², and IFN-Î³ production. It is believed that defects in the production of these cytokines increase a smoker's susceptibility to the infections mentioned above (CloÃ«z-Tayarani, 2007)
What is Swedish snuff?
Swedish snuff, or snus, is a moist powered tobacco product packed into small mesh pouches which are placed under the upper lip to speed delivery of nicotine into the body. It is a multibillion-dollar industry despite the selling of snus being illegal throughout the European Union. Swedish snuff is not the same smokeless tobacco product as American chewing or dipping tobacco.
The use of moist snuff is common in Sweden and gaining popularity in the United States. Due to the nature of the product, snuff exposes the user to high doses of nicotine. However, regulated as a food product, snuff is considered to be a safer alternative to other forms of tobacco.
In the recent Karolinska Institutet study (published in 2013), which utilized two Swedish population-based, case-control studies involving persons diagnosed with MS (n=7883) and persons without MS (n=9437, controls), subjects with different snuff use habits were compared regarding MS risk. Results indicate that snuff-users have a decreased risk by 17% of developing MS compared with those who have never used moist snuff (odds ratio [OR] 0.83, 95% confidence interval [CI] 0.75-0.92). Researchers also found evidence of an inverse relationship between increased cumulative dose of snuff use and the risk of developing the disease, meaning that the more snuff was used, the lower the risk of MS. Subjects who both smoked and used moist snuff had a lower risk of developing MS as compared to those who smoked but never used Swedish moist snuff.
In the 2009 population-based case-control study performed in Sweden, involving persons diagnosed with MS (n=902) and controls (n=1,855), the incidence of MS among smokers was compared with that of never-smokers. Both women and men smokers were 40-80% more likely to develop MS (OR 1.4, 95% CI 1.2-1.7 for women, and OR 1.8, 95% CI 1.3-2.5 for men) with the increased risk associated with smoking remaining for up to 5 years after a person stopped smoking.
In the 2009 study, persons who used Swedish snuff for more than 15 years had a 70% decreased risk of MS (OR 0.3, 95% CI 0.1-0.8) suggesting that nicotine may not be the substance responsible for the increased risk of developing MS among smokers (HedstrÃ¶m, 2009). In fact, results from the current study, which was a follow-up to the original one in published in 2009, supports the hypothesis that nicotine exerts anti-inflammatory and immune-modulating effects in a way that might decrease the risk of developing MS (HedstrÃ¶m, 2013).
Microbiology and Immunology Mobile - Immunology Chapter Thirteen: Cytokines and Immunoregulation. Accessed at http://pathmicro.med.sc.edu/mobile/m.immuno-13.htm
HedstrÃ¶m A, et al. Nicotine might have a protective effect in the etiology of multiple sclerosis. Mult Scler 2013 Jan 14. [Epub ahead of print]
HedstrÃ¶m A, et al. Exposure to environmental tobacco smoke is associated with increased risk for multiple sclerosis. Mult Scler 2011 Jul;17(7):788-93. doi: 10.1177/1352458511399610. Epub 2011 Mar 3.
HedstrÃ¶m A, et al. Tobacco smoking, but not Swedish snuff use, increases the risk of multiple sclerosis. Neurology 2009 Sep 1;73(9):696-701. doi: 10.1212/WNL.0b013e3181b59c40.
CloÃ«z-Tayarani I, Changeux JP. Nicotine and serotonin in immune regulation and inflammatory processes: a perspective. J Leukoc Biol 2007 81(3):599-606. doi: 10.1189/jlb.0906544
"Swedish Hopes Rise on Snus Ban" by Anna Molin, Wall Street Journal, October 21, 2012, accessed January 23, 2013.