Alzheimerʼs disease, Parkinsonʼs disease and schizophrenia are not inflammatory diseases while inflammation is recognizable beyond organ borders

‘Neuroinflammation’, a widely applied term in neuroscience, has no generally accepted neuropathological tissue correlates. ‘Inflammation’, characterized by the presence of perivascular infiltrates of cells of the adaptive immune system, is indeed observed in the CNS under certain conditions. Authors who refer to microglial activation as neuroinflammation confuse this issue because autoimmune neuroinflammation serves as a synonym for multiple sclerosis, the prototypical inflammatory disease of the CNS [1]. In this study, we have performed a data-driven, hypothesis-free in silico analysis to address this nomenclatorial confusion. Using two different data analysis methods, we have examined whether unsupervised analysis microarray data obtained from human cerebral cortex of Alzheimerʼs, Parkinsonʼs and schizophrenia patients show similar molecular signatures with recognized inflammatory conditions including multiple sclerosis. We report that very different sets of genes with altered expression profiles are involved in the two disease groups, namely neurodegenerative/neurodevelopmental and inflammatory disorders [2]. Our results show that the designations ‘inflammation’ and ‘neuroinflammation’ are not interchangeable and represent different categories both at the histophenotypic and transcriptomic level. Therefore, the term ‘non-autoimmune neuroinflammation’ still needs to be clarified.

This study was supported by DFG, ARC

References

[1] Graeber Brain Pathol 2014; 24:620–2 [2] Filiou et al. Neurogenetics 2014; 15:201–12