Acute particulate matter (PM ₁₀ ) 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 and psychiatric symptoms. Exposure to air pollution – and, in particular, to peaks of particulate matter (PM) – has been associated with an increase of hospital admissions for MS onset and relapses and exacerbated neuroinflammation in MS patients. Here, in the MOG _35-55 -induced experimental autoimmune encephalomyelitis (EAE) mouse model of MS, we tested the hypothesis that exposure to PM ₁₀ might influence the disease course and severity in individuals with a predisposing background. Short-term PM ₁₀ exposures – occurring either before immunization or during the pre-symptomatic 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 PM ₁₀ . These data show a selective vulnerability of immunologically primed mice toward the effects of PM ₁₀ , occurring before the emergence of overt motor impairment and presenting as specific behavioral alterations.