Comparison of the timing of acute blood-brain barrier breakdown to rabbit immunoglobulin G in the cerebellum and spinal cord of mice with experimental autoimmune encephalomyelitis.

Experimental autoimmune encephalomyelitis (EAE) is an animal model for human multiple sclerosis (MS). Similar to MS patients, EAE animals can exhibit chronic or relapsing, remitting paralysis; leukocyte infiltration of the central nervous system (CNS); and breakdown of the blood-brain barrier (BBB), allowing access to serum components. EAE pathology in rodents is generally thought to progress from the spinal cord to the more rostral brain. This common notion is based on numerous reports on the severity and progression of cellular infiltration and BBB breakdown during the course of disease. We studied opening of the BBB in EAE mice immunized to the proteolipid protein (PLP) peptide, PLP 139-151, with or without the use of pertussis toxin. Peripherally injected rabbit immunoglobulin G showed significant penetration through a compromised BBB in EAE mice and was observed throughout the parenchyma as well as intracellularly in multiple neuronal types. Results demonstrate the novel finding that the cerebellar BBB is dramatically and briefly comprised, even before breakdown of the BBB in the thoracolumbar spinal cord and prior to symptomatic disease. The demonstration of susceptibility in the cerebellum provides an important target for studying the factors predisposing certain CNS regions to autoimmune-related compromise of the BBB, such as MS.