The possibility of MS increased from exposure to organic solvents

Occupational exposure to organic solvents can increase the risk of multiple sclerosis (MS) by 50% and this risk may be even greater in people with HLA (human leukocyte antigen) at risk for MS . as suggested by a population-based Swedish study, published online in "Neurology".

Occupational exposure to organic solvents may increase the risk of multiple sclerosis (MS) by 50% and this risk may be even greater in individuals HLA (human leukocyte antigen) at risk for MS . This is suggested by a Swedish population-based study published online in "Neurology".

In addition, individuals with genetic risk factors for MS exposed to organic and smoking solvents may be 30 times more likely to develop MS. MS compared to people not exposed to these factors and without genetic risk factors, write the authors, coordinated by Anna Hedstrom of the Karolinska Institute of Stockholm (Sweden).

Demonstrated gene-environment interaction in multiple sclerosis
"We discovered that the gene-environment interaction actually takes place: the combined effect of HLA genes at risk of MS and exposure to organic solvents is much higher than the sum of the individual effects of the exposures "the researchers add. In MS, the strongest genetic badociations reside in the HLA complex: the HLA-DRB1 * 15 allele is linked to an increased risk of MS while the HLA-A * 02 allele may have an effect protective.

Tobacco exposure has been badociated with a higher risk of MS in people with HLA genes at risk for MS and exposure to organic solvents – another source of pulmonary irritation – may be a risk factor for autoimmune diseases. It has also been shown that smoking accelerates the progression of MS

Survey of Workers in the Painting Industry
For this badysis (1), researchers badyzed data from the past. a case-control study with incident cases of MS (2,042 cases and 2,947 controls), corresponding to age, bad and residential area.

Participants were recruited between April 2005 and December 2013 and reported on environmental and lifestyle exposures using standardized questionnaires. Individuals who reported having been professionally exposed to organic solvents, paint products or paints before the reference year were defined as "exposed to organic solvents".

The average age at onset of MS was 34 years old. 76% of MS patients were women. Most of the cases involved relapsing remitting MS. Almost all cases were recruited in the year following the diagnosis of MS; the questionnaires were completed with a median of 2 years after the onset of the disease

The researchers compared the onset of MS in people with different genotypes, smoking habits and exposure to organic solvents, calculating an attributable proportion (AP) based on the interaction of exposure to solvents and genes at risk of MS

Exposure to organic solvents increases the risk of multiple sclerosis (OR 1 , 5, 95% CI 1.2 to 1.8, P = 0.0004), with increased duration and total hours of exposure to the solvent. There was a significant three-way interaction between exposure to organic solvents, the presence of HLA-DRB1 * 15 and the absence of HLA-A * 02, with a risk of MS (AP 0.6 , 95% CI,

Even among HLA-DRB1 * 15 positive individuals lacking the HLA-0 * 02 protective allele, there was a significant interaction between organic solvents and smoke (AP 0, 7, 95% CI 0.4-1.0) People exposed to tobacco and organic solvents carrying HLA-DRB1 * 15 and lacking HLA-A * 02 were 30 times more likely to develop MS than those exposed to not exposed to the agents mentioned and without genetic risk factors (OR 30, 3, 95% CI 11.7 to 78.3)

The interaction between organic solvents, HLA-DRB1 * 15 and HLA-A * 02 was similar to that reported previously, which implicated the same HLA genes at risk of MS and tobacco exposure, Hedstrom and colleagues note.

Irritati Chronic pulmonary and CNS direct effects
"This could indicate that chronic pulmonary irritation, caused by smoking or exposure to organic solvents, contributes to an immune response that causes MS, mainly in people with MS. Hedstrom and his colleagues state, "We intend to conduct a study of taxfilers to determine if air pollution is a predisposing factor to the disease," according to the researchers

. a risk factor for the disease. "

In an editorial commentary (2) Jack Bell and Gabriele DeLuca of the University of Oxford (United Kingdom) note that Organic solvents have also direct effects on the central nervous system (CNS) that may be relevant. "Organic solvents are highly lipophilic, which allows them to easily enter the systemic circulation, cross the blood-brain barrier and s & # 39; accumulate in the fat-rich CNS, "they write,"

"Here the solvents penetrate directly into the lipid membrane. and interfere with the treatment of fatty acids, "they continue. Repeated exposure to solvents can also compromise the blood-brain barrier and lead to perivascular macrophage-mediated demyelination, similar to that of MS, by adding Bell and DeLuca.

The researchers eventually found several limitations of this badysis, including which bias potential for selection and recall (recall bias).

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References:
1) Hedström AK, Hössjer O, Katsoulis M, et al. Organic solvents and susceptibility to MS: Interaction with HLA genes at risk of MS. Neurology, 2018 Jul 3. doi: 10.1212 / WNL.0000000000005906. [Epub ahead of print] read

2) Bell JS, DeLuca GC. Genes, smoking and exposure to organic solvents: an alarming badtail for the risk of MS. Neurology. 2018 Jul 3. doi: 10.1212 / WNL.0000000000005896. [Epub ahead of print] read