Résumé
Autoimmune encephalitis (AE) is a diverse group of inflammatory brain parenchyma diseases. Some of them, lacking identifiable autoantibodies are called antibody-negative AE (NAE) and pose diagnostic challenges. This study aims to evaluate the diagnostic and prognostic value of cytokine assays in cerebrospinal fluid (CSF) for patients with NAE and antibody-positive AE (PAE).Materials and methods: a retrospective analysis was carried out on 21 NAE patients, 11 PAE patients, 11 healthy controls (HC) and 24 controls with inflammatory diseases of the central nervous system (IC). Clinical, magnetic resonance imaging (MRI), electroencephalography (EEG), cerebrospinal fluid (CSF) and positron emission tomography (PET) data were evaluated. Fifty-four CSF cytokines were measured and compared, first between the NAE and PAE groups, then between the AE (NAE+PAE), IC and HC groups. Cytokines that showed a significant difference between groups were then assessed in multivariate analysis and ROC curves were created for their ability to discriminate between groups AE and HC. Correlation between cytokine levels and prognostic data (mRS score, relapse, death) in the AE group was also assessed.Results: there were no significant differences between NAE and PAE for clinical, paraclinical and CSF cytokine assays. Significant differences were found between AE and HC for Th1 (IP-10, IL-12p40, IFNγ), Th2 (TARC, TSLP, MDC, eotaxin) and Th17 (IL-8) cytokines, and between AE and IC for IL-17B and SAA. IP-10 assay provided the best univariate ROC curve. Markers of vascular damage (ICAM-1, VCAM1, SAA) were elevated in the AE group compared with HC. IL-6, IL-10, IL-1ra, VEGF-D and CRP were associated with mRS at last follow-up, while SAA and CRP were correlated with death.Conclusion: patients with AE (both NAE and PAE) have a distinct cytokine profile in CSF compared with controls, with a Th17 axis emerging as a potential target for future investigations and a possible contribution of IP-10 assay in diagnosis. A possible link between AE, elevated markers of vascular damage, disruption of the blood-brain barrier and a pro-thrombotic state warrants further investigations. Despite limitations, this study suggests that certain cytokines and chemokines in the CSF of AE patients may have diagnostic and prognostic value, which needs to be confirmed by future studies.