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Balloon cells promote immune system activation in focal cortical dysplasia type 2b
Author(s) -
Zimmer Till S.,
Broekaart Diede W. M.,
Luinenburg Mark,
Mijnsbergen Caroline,
Anink Jasper J.,
Sim Nam Suk,
Michailidou Iliana,
Jansen Floor E.,
Rijen Peter C.,
Lee Jeong Ho,
François Liesbeth,
Eyll Jonathan,
Dedeurwaerdere Stefanie,
Vliet Erwin A.,
Mühlebner Angelika,
Mills James D.,
Aronica Eleonora
Publication year - 2021
Publication title -
neuropathology and applied neurobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.538
H-Index - 95
eISSN - 1365-2990
pISSN - 0305-1846
DOI - 10.1111/nan.12736
Subject(s) - cortical dysplasia , immune system , acquired immune system , innate immune system , biology , immunohistochemistry , pathology , pi3k/akt/mtor pathway , inflammation , immunology , medicine , neuroscience , signal transduction , epilepsy , microbiology and biotechnology
Aims Focal cortical dysplasia (FCD) type 2 is an epileptogenic malformation of the neocortex associated with somatic mutations in the mammalian target of rapamycin (mTOR) pathway. Histopathologically, FCD 2 is subdivided into FCD 2a and FCD 2b, the only discriminator being the presence of balloon cells (BCs) in FCD 2b. While pro‐epileptogenic immune system activation and inflammatory responses are commonly detected in both subtypes, it is unknown what contextual role BCs play. Methods The present study employed RNA sequencing of surgically resected brain tissue from FCD 2a ( n = 11) and FCD 2b ( n = 20) patients compared to autopsy control ( n = 9) focusing on three immune system processes: adaptive immunity, innate immunity and cytokine production. This analysis was followed by immunohistochemistry on a clinically well‐characterised FCD 2 cohort. Results Differential expression analysis revealed stronger expression of components of innate immunity, adaptive immunity and cytokine production in FCD 2b than in FCD 2a, particularly complement activation and antigen presentation. Immunohistochemical analysis confirmed these findings, with strong expression of leukocyte antigen I and II in FCD 2b as compared to FCD 2a. Moreover, T‐lymphocyte tissue infiltration was elevated in FCD 2b. Expression of markers of immune system activation in FCD 2b was concentrated in subcortical white matter. Lastly, antigen presentation was strongly correlated with BC load in FCD 2b lesions. Conclusion We conclude that, next to mutation‐driven mTOR activation and seizure activity, BCs are crucial drivers of inflammation in FCD 2b. Our findings indicate that therapies targeting inflammation may be beneficial in FCD 2b.