Annals of Clinical and Translational Neurology

Altered exosomal miRNA profiles in patients with paraneoplastic cerebellar degeneration

AbstractObjectivePatients with ovarian cancer (OC) may develop anti‐Yo‐associated paraneoplastic cerebellar degeneration (PCD)—a cerebellar ataxia associated with tumor‐induced autoimmunity against CDR2 and CDR2L proteins. Dysregulation of circulating exosomal microRNAs (miRNAs) occur in OC. Here, we investigated whether PCD is associated with changes in the exosomal miRNA profiles of OC patients.MethodsSerum exosomes were isolated from patients with OC (n = 15), patients with OC and anti‐Yo‐associated PCD (n = 14) and healthy controls (HC, n = 15). Small RNA sequencing was used to identify differentially expressed miRNAs. Receiver operating characteristic curves were used to evaluate biomarker sensitivity and specificity, and miRNA target prediction analysis was employed to elucidate gene targets.ResultsOC patients with PCD exhibited a distinct exosomal miRNA expression profile. We detected 103 differentially expressed exosomal miRNAs in PCD patients compared to OC patients without PCD and 139 differentially expressed exosomal miRNAs compared to controls. Particularly miR‐486‐5p, miR‐4732‐5p, miR‐98‐5p and miR‐21‐5p exhibited notable sensitivity and specificity for discriminating PCD patients from both OC patients without PCD and healthy controls. miRNA target prediction showed that several of the differentially expressed miRNAs in PCD patients targeted the CDR2 and CDR2L genes.InterpretationOur results demonstrate that OC patients with anti‐Yo‐associated PCD exhibit a distinct exosomal miRNA profile compared to OC patients without PCD. Several of the differentially expressed exosomal miRNAs in PCD patients showed diagnostic potential and may hold relevance for understanding the pathogenesis of PCD.

Teratoma pathology and genomics in anti‐NMDA receptor encephalitis

AbstractIntroductionOvarian teratoma is a common occurrence in patients with anti‐NMDA receptor encephalitis (NMDARe), and its removal is crucial for a favorable prognosis. However, the initial pathogenesis of autoimmunity in the encephalitic teratoma remains unclear. In this study, we aimed to investigate the genomic landscape and microscopic findings by comparing NMDARe‐associated teratomas and non‐encephalitic control teratomas.Materials and MethodsA prospective consecutive cohort of 84 patients with NMDARe was recruited from January 2014 to April 2020, and among them, patients who received teratoma removal surgery at Seoul National University Hospital were enrolled. We conducted a comparison of whole‐exome sequencing data and pathologic findings between NMDARe‐associated teratomas and control teratomas.ResultsWe found 18 NMDARe‐associated teratomas from 15 patients and compared them with 17 non‐encephalitic control teratomas. Interestingly, the genomic analysis revealed no significant differences in mutations between encephalitic and non‐encephalitic teratomas. Pathologic analysis showed no discrepancies in terms of the presence of neuronal tissue and lymphocytic infiltration between the encephalitic teratomas (n = 14) and non‐encephalitic teratomas (n = 18). However, rituximab‐naïve encephalitic teratomas exhibited a higher frequency of germinal center formation compared to non‐encephalitic teratomas (80% vs. 16.7%, P = 0.017). Additionally, rituximab‐treated encephalitic teratomas demonstrated a reduced number of CD20+ cells and germinal centers in comparison to rituximab‐naïve encephalitic teratomas (P = 0.048 and 0.023, respectively).DiscussionThese results suggest that the initiation of immunopathogenesis in NMDARe‐associated teratoma is not primarily attributed to intrinsic tumor mutations, but rather to immune factors present in the encephalitic patient group, ultimately leading to germinal center formation within the teratoma.