Experimental evidence for alpha enolase as one potential autoantigen in the pathogenesis of both autoimmune thyroiditis and its related encephalopathy

Alpha-enolase (ENO1) is a ubiquitous protein. Patients with autoimmune thyroiditis-associated encephalopathy have high serum ENO1Ab titers. We aimed to explore whether ENO1Ab was the pathogenic antibody in the thyroid and brain. The serum ENO1Ab titers were significantly increased in the mice immunized with Thyroglobulin (Tg). And in the mice immunized with ENO1, serum levels of both TgAb and thyroid-stimulating hormone (TSH) were significantly increased. Obvious CD16+ cell infiltration, IgG deposit and cleaved caspase-3 were observed in the thyroid of ENO1-immunized mice. Spatial learning and memory abilities and synaptic functions were impaired in ENO1-immunized mice. Furthermore, the expression levels of Iba-1, GFAP, interlukin-6, CDK5, and phosphorylated tau were increased, and endothelial tight junction proteins were decreased in the brain of ENO1-immunized mice. These results suggest that ENO1Ab can cause thyrocyte damage via ADCC effect and impair cerebral function by disrupting the blood–brain barrier.