Acute Particulate Matter (PM10) Exposure Selectively Triggers Behavioral Alterations in the Presymptomatic Experimental Autoimmune Encephalomyelitis (EAE) Mouse Model of Multiple Sclerosis

Multiple sclerosis (MS) is a chronic disease of the central nervous system, where neuroinflammation and autoimmune response against myelin lead to functional impairments, cognitive and psychiatric symptoms. Exposure to air pollution—in particular to peaks of particulate matter (PM)—has been associated with an increase in hospital admissions for MS onset and relapses and exacerbated neuroinflammation in MS patients. Here, in the MOG35–55-induced experimental autoimmune encephalomyelitis (EAE) mouse model of MS, we tested the hypothesis that exposure to PM10 might influence the disease course and severity in individuals with a predisposing background. Short-term PM10 exposures—occurring either before immunization or during the presymptomatic phase—did not modify disease manifestation in EAE mice, as assessed by clinical and neuropathological analyses. Yet, presymptomatic EAE—but not healthy—mice selectively showed increased disinhibited, risk-taking, and novelty-seeking behaviors early after being exposed to PM10. These data show a selective vulnerability of immunologically primed mice toward the effects of PM10, occurring before the emergence of overt motor impairment and presenting as specific behavioral alterations.