In vivo evolution by brain Magnetic Resonance Imaging of Interleukin 1 induced cortical demyelinating lesions in adult rats

BERENICE ANABEL SILVA; AVALOS, JUAN CARLOS; MARIA ISABEL FARIAS; MARIA CELESTE LEAL; BESADA, CRISTINA HILDA; PITOSSI, FERNANDO JUAN; CARINA C FERRARI

Paris

Congreso; ECTRIMS 2017; 2018

European Committee for Treatment and Research In Multiple Sclerosis

Therelevance of the interleukin 1beta (IL-1b) has been demonstrated in both MultipleSclerosis (MS) pathology and MS animal models. The aim of this work is to analyzerat brain magnetic resonance imaging (MRI) and their correlation with thehistological features of cortical demyelinating lesions induced by thelong-term expression of IL-1b in adult rats.  Adult rats were injected in prefrontal cortex withan adenovirus expressing IL-1b (AdIL-1). Then, 21 days after they were peripherallyinjected with either AdIL-1 or control adenovirus (CI/PI and CI/PC,respectively) and analyzed by 3 T MRI and histological techniques 7 days afterthe peripheral stimulation. Anatomopathological studies and brain blood barrier(BBB) integrity were assessed. The peripherally stimulated cortical lesions of CI/PIshowed hyperintensity on T2-weighted sequence and homogeneous enhancement on T1-weighted sequence, after injection of a gadolinium-based contrast agent, withmaximum enhancement six minutes after gadolinium injection, indicating lack ofblood-brain barrier.  We do not observedhyperintensity and gadolinium enhancement in cortical lesions of CI/PC animals.In spite of that, cortical lesions exhibited neuroinflammation,neurodegeneration, demyelination, meningeal inflammation and BBB disruption in bothgroups CI/PI and CI/PC. We analyzed the differences in the composition of bothcortical lesions, and we found that the presence of neutrophils is significantlyhigher in CI/PI cortex, which could be responsible for MRI visualization onT2-weighted sequence. Given that no MRI lesion images can be visualized in CI/PCanimals, even though tissue damage and BBB leakage is present, the phenomenondescribes as normal appearing gray matter could explain these results. Inaddition, this study constitutes another evidence confirming that the lowsensitivity of gadolinium in reflecting BBB disruption. Therefore, the use ofconventional MRI protocols and the sensitivity of gadolinium to demonstrate BBBintegrity should be discussed.