We examined the expression and localization of osteopontin (OPN) in various organs in mice with experimental autoimmune encephalomyelitis (EAE). To evaluate the level of OPN in blood and various tissues, enzyme-linked immunosorbent assay and western blot analysis of OPN were performed. The serum level of OPN was significantly increased in mice with EAE, and OPN was upregulated in all tissues examined, including the liver, kidneys, intestines, and spinal cord.OPN immunoreactivity was noted in inflammatory cells (mainly macrophages) and was enhanced in constitutively expressed cell types in the examined organs. In sum, OPN, a pro-inflammatory and immunomodulatory mediator, was elevated in all tissues following EAE induction, resulting in increased blood concentrations. These findings suggest that OPN may function as a key extracellular matrix component contributing to systemic disorders in autoimmune disease models.

Objective: This study evaluated the inflammatory response in lungs of EAE mice by immunohistochemistry and histochemistry. Methods: Eight adult C57BL/6 mice were injected with myelin oligodendrocyte glycoprotein 35-55 to induce the EAE. Lungs and spinal cords were sampled from the experimental mice at the time of sacrifice and used for the western blotting, histochemistry, and immunohistochemistry. Results: Histopathological examination revealed inflammatory lesions in the lungs of EAE mice, characterized by infiltration of myeloperoxidase (MPO)- and galectin-3-positive cells, as determined by immunohistochemistry. Increased numbers of collagen fibers in the lungs of EAE mice were confirmed by histopathological analysis. Western blotting revealed significantly elevated level of osteopontin (OPN), cluster of differentiation 44 (CD44), MPO and galectin-3 in the lungs of EAE mice compared with normal controls (p < 0.05).Immunohistochemical analysis revealed both OPN and CD44 in ionized calcium-binding adapter molecule 1-positive macrophages within the lungs of EAE mice. Conclusions and Relevance: Taken together, these findings suggest that the increased OPN level in lungs of EAE mice led to inflammation; concurrent increases in proinflammatory factors (OPN and galectin-3) caused pulmonary impairment.