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

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

Paris

Congreso; 7th JOINT ECTRIMS-ACTRIMS; 2017

The relevance of the interleukin 1beta (IL-1b) has been demonstrated in both Multiple Sclerosis (MS) pathology and MS animal models. The aim of this work is to analyze rat brain magnetic resonance imaging (MRI) and their correlation with the histological features of cortical demyelinating lesions induced by the long-term expression of IL-1b in adult rats. Adult rats were injected in prefrontal cortex with an adenovirus expressing IL-1b (AdIL-1). Then, 21 days after they were peripherally injected with either AdIL-1 or control adenovirus (CI/PI and CI/PC, respectively) and analyzed by 3 T MRI and histological techniques 7 days after the peripheral stimulation. Anatomopathological studies and brain blood barrier (BBB) integrity were assessed. The peripherally stimulated cortical lesions of CI/PI showed hyperintensity on T2-weighted sequence and homogeneous enhancement on T1- weighted sequence, after injection of a gadolinium-based contrast agent, with maximum enhancement six minutes after gadolinium injection, indicating lack of blood-brain barrier. We do not observed hyperintensity 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 both groups CI/PI and CI/PC. We analyzed the differences in the composition of both cortical lesions, and we found that the presence of neutrophils is significantly higher in CI/PI cortex, which could be responsible for MRI visualization on T2-weighted sequence. Given that no MRI lesion images can be visualized in CI/PC animals, even though tissue damage and BBB leakage is present, the phenomenon describes as normal appearing gray matter could explain these results. In addition, this study constitutes another evidence confirming that the low sensitivity of gadolinium in reflecting BBB disruption. Therefore, the use of conventional MRI protocols and the sensitivity of gadolinium to demonstrate BBB integrity should be discussed.EL SISTEMA NO ME DEJA PONER NUEVAS FILIACIONES PARA LOS AUTORES