Association between the peptide spectrum match values of LGI1, ADAM22, ADAM23 and DLG4 in the immunoprecipitation products of five autoimmune encephalitis cases with LGI1 antibody: A case series

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Background LGI1 antibody is one of the most important antibodies associated with autoimmune encephalitis. A biological biomarker for assessing disease severity in LGI1 antibody-associated encephalitis has not yet been established. In this study, we used serum and cerebrospinal fluid (CSF) from patients with LGI1 antibody-positive encephalitis to immunoprecipitate antigens from mouse brain tissue, and the immunoprecipitation (IP) products were subsequently analyzed using mass spectrometry (IP-shotgun proteomics). Methods Five patients with LGI1 antibody-positive cases were included in the patient group. The control group comprised healthy individuals, those with idiopathic normal pressure hydrocephalus, and NMDAR antibody-positive cases. IP-shotgun proteomics was performed for each sample, and specific amino acid sequences identified in the immunoprecipitated products were quantified as peptide spectrum match (PSM) values. We analyzed the PSM values of LGI1 and its binding partners, ADAM22, ADAM23, and DLG4. Results The PSM values of LGI1, ADAM22, and ADAM23 were significantly higher in IP products using sera and CSF from patients with AE with LGI1 antibody than in those from the control group. The most severe case showed the highest PSM values for LGI1, ADAM22, ADAM23, and DLG4 in both serum and CSF, and the mildest case showed the lowest PSM values for these proteins. Conclusion In LGI1 antibody-positive cases, the PSM values of LGI1, ADAM22, ADAM23, and DLG4, which form a complex with LGI1, were higher than those in the control group. Further studies are required to determine whether these PSM values have diagnostic utility and can thus serve as biomarkers of disease severity.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.