Pettingill Philippa, Kramer Holger B, Coebergh Jan Adriaan, Pettingill Rosie, Maxwell Susan, Nibber Anjan, Malaspina Andrea, Jacob Anu, Irani Sarosh R, Buckley Camilla, Beeson David, Lang Bethan, Waters Patrick, Vincent Angela
From the Nuffield Department of Clinical Neurosciences (P.P., R.P., S.M., A.N., S.R.I., C.B., D.B., B.L., P.W., A.V.) and the Department of Physiology, Anatomy and Genetics (H.B.K.), University of Oxford; St George's Healthcare NHS Trust (J.A.C.), Tooting, London; the Centre for Neuroscience & Trauma, Blizard Institute (A.M.), Barts and The London School of Medicine and Dentistry, Queen Mary University of London; and The Walton Centre Foundation Trust (A.J.), Liverpool, UK.
Neurology. 2015 Mar 24;84(12):1233-41. doi: 10.1212/WNL.0000000000001326. Epub 2015 Jan 30.
To search for antibodies against neuronal cell surface proteins.
Using immunoprecipitation from neuronal cultures and tandem mass spectrometry, we identified antibodies against the α1 subunit of the γ-aminobutyric acid A receptor (GABAAR) in a patient whose immunoglobulin G (IgG) antibodies bound to hippocampal neurons. We searched 2,548 sera for antibodies binding to GABAAR α, β, and γ subunits on live HEK293 cells and identified the class, subclass, and GABAAR subunit specificities of the positive samples.
GABAAR-Abs were identified in 40 of 2,046 (2%) referred sera previously found negative for neuronal antibodies, in 5/502 (1%) previously positive for other neuronal surface antibodies, but not in 92 healthy individuals. The antibodies in 40% bound to either the α1 (9/45, 20%) or the γ2 subunits (9/45, 20%) and were of IgG1 (94%) or IgG3 (6%) subclass. The remaining 60% had lower antibody titers (p = 0.0005), which were mainly immunoglobulin M (IgM) (p = 0.0025), and showed no defined subunit specificity. Incubation of primary hippocampal neurons with GABAAR IgG1 sera reduced surface GABAAR membrane expression. The clinical features of 15 patients (GABAAR α1 n = 6, γ2 n = 5, undefined n = 4) included seizures (47%), memory impairment (47%), hallucinations (33%), or anxiety (20%). Most patients had not been given immunotherapies, but one with new-onset treatment-resistant catatonia made substantial improvement after plasma exchange.
The GABAAR α1 and γ2 are new targets for antibodies in autoimmune neurologic disease. The full spectrum of clinical features, treatment responses, correlation with antibody specificity, and in particular the role of the IgM antibodies will need to be assessed in future studies.
寻找抗神经元细胞表面蛋白的抗体。
利用神经元培养物中的免疫沉淀和串联质谱分析，我们在一名免疫球蛋白G（IgG）抗体与海马神经元结合的患者中鉴定出了抗γ-氨基丁酸A受体（GABAAR）α1亚基的抗体。我们在2548份血清中搜索与活的HEK293细胞上的GABAARα、β和γ亚基结合的抗体，并确定阳性样本的类别、亚类和GABAAR亚基特异性。
在先前检测神经元抗体呈阴性的2046份送检血清中的40份（2%）、先前检测其他神经元表面抗体呈阳性的502份中的5份（1%）中鉴定出GABAAR抗体，但在92名健康个体中未检测到。40%的抗体与α1（9/45，20%）或γ2亚基（9/45，20%）结合，且为IgG1亚类（94%）或IgG3亚类（6%）。其余60%的抗体滴度较低（p = 0.0005），主要为免疫球蛋白M（IgM）（p = 0.0025），且未显示出明确的亚基特异性。用GABAAR IgG1血清孵育原代海马神经元可降低表面GABAAR膜表达。15名患者（GABAAR α1亚基6例，γ2亚基5例，未明确亚基4例）的临床特征包括癫痫发作（47%）、记忆障碍（47%）、幻觉（33%）或焦虑（20%）。大多数患者未接受过免疫治疗，但1例新发难治性紧张症患者在进行血浆置换后有显著改善。
GABAAR α1和γ2是自身免疫性神经疾病中抗体的新靶点。未来的研究需要评估临床特征的全貌、治疗反应、与抗体特异性的相关性，尤其是IgM抗体的作用。
