The Effect of Smoking and Passive Exposure on Multiple Sclerosis and Correlation with IL17 & IL23 Levels

The aim of the study was to investigate whether there is any effect of smoking status or passive exposure on different subtypes of multiple sclerosis (MS) and their association with the IL17 & IL23 levels.

Blood samples were obtained from patients diagnosed with clinically isolated syndrome (CIS), relapsing remitting MS (RRMS), primary progressive MS (PPMS), secondary progressive MS (SPMS) and healthy controls. Smoking habits and passive exposure were questioned via a specifically created questionnaire. Patients and controls were grouped into three subgroups according to smoking status as active smokers, former smokers and never smokers.

There were 60 patients and 20 age and sex-matched healthy controls. Active smoking was associated with a higher relapse rate per year. Smoking was inversely proportional to IL23 levels. Passive smoking was associated with atrophy in the follow-up cranial MRI. In utero exposure was associated with a polysymptomatic disease onset. The onset symptoms differed between patients whose mothers smoked during their childhood.

This study shows the effects of smoking and passive smoking on the presenting symptoms and course of MS. The relationship between these adverse effects and the Th17 pathway is not clear. It is evident that MS patients should be advised against smoking and should be directed to programs for quitting smoking.