Ozone, NO2 and PM10 are associated with the occurrence of multiple sclerosis relapses. Evidence from seasonal multi-pollutant analyses

Abstract

Background Triggers of multiple sclerosis (MS) relapses are essentially unknown. PM10 exposure has recently been associated with an increased risk of relapses. Objectives We further explore the short-term associations between PM10, NO2, benzene (C6H6), O3, and CO exposures, and the odds of MS relapses’ occurrence. Methods Using a case-crossover design, we studied 424 MS patients living in the Strasbourg area, France between 2000 and 2009 (1783 relapses in total). Control days were chosen to be±35 days relative to the case (relapse) day. Exposure was modeled through ADMS-Urban software at the census block scale. We consider single-pollutant and multi-pollutant conditional logistic regression models coupled with a distributed-lag linear structure, stratified by season (“hot” vs. “cold”), and adjusted for meteorological parameters, pollen count, influenza-like epidemics, and holidays. Results The single-pollutant analyses indicated: 1) significant associations between MS relapse incidence and exposures to NO2, PM10, and O3, and 2) seasonality in these associations. For instance, an interquartile range increase in NO2 (lags 0–3) and PM10 exposure were associated with MS relapse incidence (OR = 1.08; 95%CI: [1.03–1.14] and OR = 1.06; 95%CI: [1.01–1.11], respectively) during the “cold” season (i.e., October-March). We also observed an association with O3 and MS relapse incidence during “hot” season (OR = 1.16; 95%CI: [1.07–1.25]). C6H6 and CO were not significantly related to MS relapse incidence. However, using multi-pollutant models, only O3 remained significantly associated with the odds of relapse triggering during “hot” season. Conclusion We observed significant single-pollution associations between the occurrence of MS relapses and exposures to NO2, O3 and PM10, only O3 remained significantly associated with occurrence of MS relapses in the multi-pollutant model.

Identifying the culprits in neurological autoimmune diseases

“…Exposure to air pollutants initiates pathological processes in MS and leads to cerebral autoimmunity through inflammatory-oxidative cascades, loss of immunological tolerance, and neurodegeneration [ 187 ]. NO2, O3, and PM10 are associated with the appearance of MS relapses [ 188 ]. In fact, PM10 contributes to MS relapses through oxidative stress mechanisms [ 189 ].…”

Air Pollution as a Contributor to the Inflammatory Activity of Multiple Sclerosis

“…In a recent study, we have established a significant association between air-borne particulate matter levels and inflammatory activity of the disease, as expressed by the presence of gadoliniumenhancing lesions on brain MRI in MS patients (9). Other groups have also observed an association between ambient levels of air pollution and MS prevalence (10), as well as clinical activity of the disease (11)(12)(13)(14).…”

Environmental and genetic risk factors for MS: an integrated review

“…A few studies have shown an association between PM 10 levels and risk of MS relapse or MRI activity . A deeper look at various pollutants suggested an increased risk of MS relapse following recent exposure to nitrogen dioxide (particularly during the cold season) or ozone (particularly for the hot season) . Benzene and carbon monoxide were not associated with MS relapses.…”