Francesc Graus

Investigation of LGI1 as the antigen in limbic encephalitis previously attributed to potassium channels: a case series

BACKGROUND Voltage-gated potassium channels are thought to be the target of antibodies associated with limbic encephalitis. However, antibody testing using cells expressing voltage-gated potassium channels is negative; hence, we aimed to identify the real autoantigen associated with limbic encephalitis. METHODS We analysed sera and CSF of 57 patients with limbic encephalitis and antibodies attributed to voltage-gated potassium channels and 148 control individuals who had other disorders with or without antibodies against voltage-gated potassium channels. Immunohistochemistry, immunoprecipitation, and mass spectrometry were used to characterise the antigen. An assay with HEK293 cells transfected with leucine-rich, glioma-inactivated 1 (LGI1) and disintegrin and metalloproteinase domain-containing protein 22 (ADAM22) or ADAM23 was used as a serological test. The identity of the autoantigen was confirmed by immunoabsorption studies and immunostaining of Lgi1-null mice. FINDINGS Immunoprecipitation and mass spectrometry analyses showed that antibodies from patients with limbic encephalitis previously attributed to voltage-gated potassium channels recognise LGI1, a neuronal secreted protein that interacts with presynaptic ADAM23 and postsynaptic ADAM22. Immunostaining of HEK293 cells transfected with LGI1 showed that sera or CSF from patients, but not those from control individuals, recognised LGI1. Co-transfection of LGI1 with its receptors, ADAM22 or ADAM23, changed the pattern of reactivity and improved detection. LGI1 was confirmed as the autoantigen by specific abrogation of reactivity of sera and CSF from patients after immunoabsorption with LGI1-expressing cells and by comparative immunostaining of wild-type and Lgi1-null mice, which showed selective lack of reactivity in brains of Lgi1-null mice. One patient with limbic encephalitis and antibodies against LGI1 also had antibodies against CASPR2, an autoantigen we identified in some patients with encephalitis and seizures, Morvans syndrome, and neuromyotonia. INTERPRETATION LGI1 is the autoantigen associated with limbic encephalitis previously attributed to voltage-gated potassium channels. The term limbic encephalitis associated with antibodies against voltage-gated potassium channels should be changed to limbic encephalitis associated with LGI1 antibodies, and this disorder should be classed as an autoimmune synaptic encephalopathy. FUNDING National Institutes of Health, National Cancer Institute, and Euroimmun.

Antibodies to the GABAB receptor in limbic encephalitis with seizures: case series and characterisation of the antigen

BACKGROUND Some encephalitides or seizure disorders once thought idiopathic now seem to be immune mediated. We aimed to describe the clinical features of one such disorder and to identify the autoantigen involved. METHODS 15 patients who were suspected to have paraneoplastic or immune-mediated limbic encephalitis were clinically assessed. Confocal microscopy, immunoprecipitation, and mass spectrometry were used to characterise the autoantigen. An assay of HEK293 cells transfected with rodent GABA(B1) or GABA(B2) receptor subunits was used as a serological test. 91 patients with encephalitis suspected to be paraneoplastic or immune mediated and 13 individuals with syndromes associated with antibodies to glutamic acid decarboxylase 65 were used as controls. FINDINGS All patients presented with early or prominent seizures; other symptoms, MRI, and electroencephalography findings were consistent with predominant limbic dysfunction. All patients had antibodies (mainly IgG1) against a neuronal cell-surface antigen; in three patients antibodies were detected only in CSF. Immunoprecipitation and mass spectrometry showed that the antibodies recognise the B1 subunit of the GABA(B) receptor, an inhibitory receptor that has been associated with seizures and memory dysfunction when disrupted. Confocal microscopy showed colocalisation of the antibody with GABA(B) receptors. Seven of 15 patients had tumours, five of which were small-cell lung cancer, and seven patients had non-neuronal autoantibodies. Although nine of ten patients who received immunotherapy and cancer treatment (when a tumour was found) showed neurological improvement, none of the four patients who were not similarly treated improved (p=0.005). Low levels of GABA(B1) receptor antibodies were identified in two of 104 controls (p<0.0001). INTERPRETATION GABA(B) receptor autoimmune encephalitis is a potentially treatable disorder characterised by seizures and, in some patients, associated with small-cell lung cancer and with other autoantibodies. FUNDING National Institutes of Health.

Spectrum of neurological syndromes associated with glutamic acid decarboxylase antibodies: diagnostic clues for this association

The association of high levels of autoantibodies to glutamic acid decarboxylase (GAD-ab) and stiff-person syndrome (SPS) is well known. However, the full spectrum of neurological syndromes associated with GAD-ab is not well established. In addition, these patients usually present type 1 diabetes mellitus (DM1) that could justify the presence of high GAD-ab levels. To clarify these issues, we reviewed the clinical and immunological features of patients in whom high GAD-ab levels were detected in a reference centre for DM1 and for the detection of antineuronal antibodies in suspected paraneoplastic neurological syndromes (PNS). High GAD-ab levels were defined as values > or =2000 U/ml by radioimmunoassay. Intrathecal synthesis (IS) of GAD-ab was calculated in paired serum/CSF samples. Values higher than the IgG index were considered indicators for positive GAD-ab-specific IS. High GAD-ab levels were identified in 61 patients, 22 (36%) had SPS, 17 (28%) cerebellar ataxia, 11 (18%) other neurological disorders (epilepsy -- four, PNS -- four; idiopathic limbic encephalitis -- two; myasthenia gravis -- one), and 11 (18%) isolated DM1. Patients with SPS and cerebellar ataxia had the same frequency of female gender (86% vs 94%), DM1 (59% vs 53%), CSF oligoclonal bands (35% vs 69%). Three of the four PNS patients, with paraneoplastic encephalomyelitis, a predominant gait cerebellar ataxia, and limbic encephalitis, had neuroendocrine carcinomas. GAD expression was confirmed in the two tumours in which the study was done. The fourth patient presented with paraneoplastic cerebellar degeneration antedating a lung adenocarcinoma. The frequency of increased IS of GAD-ab was 85% in SPS, 100% in cerebellar ataxia, and 86% in other neurological disorders. In conclusion, our study emphasizes that high GAD-ab levels associate with other neurological disorders besides SPS. Cerebellar ataxia, the second most common syndrome associated with high GAD-ab levels, shares with SPS the same demographic, clinical and immunological features. The demonstration of an increased IS of GAD-ab is important to confirm that the GAD autoimmunity is related to the neurological syndrome particularly when there is a concomitant DM1 that could justify the presence of high GAD-ab levels. Lastly, in patients who develop neurological syndromes that suggest a PNS, the finding of GAD-ab does not rule out this possibility and appropriate studies should be done to confirm an underlying cancer.

Guidelines on management of low-grade gliomas: report of an EFNS-EANO* Task Force

Background:  Diffuse infiltrative low‐grade gliomas of the cerebral hemispheres in the adult are a group of tumors with distinct clinical, histological and molecular characteristics, and there are still controversies in management.

Neuronal antinuclear antibody in sensory neuronopathy from lung cancer

We found an antinuclear antibody highly restricted to nuclei of neurons in two patients with subacute sensory neuronopathy complicating oat cell carcinoma of the lung. Serum was tested by indirect immunofluorescence and immunoperoxidase staining. At low concentrations of antibody, only the nuclei of the neurons were stained. At high concentrations, there was also staining of the nuclei of glial cells and fetal nonneural tissues. The cytoplasm of most neurons was stained with the immunoperoxidase method.

Antibodies and neuronal autoimmune disorders of the CNS.

We review the neuronal antibodies described in CNS disorders in order to clarify their diagnostic value, emphasize potentials pitfalls and limitations in the diagnosis of paraneoplastic neurological syndromes (PNS), and examine the current evidence for a possible pathogenic role. We propose to classify the neuronal antibodies associated with syndromes resulting from CNS neuronal dysfunction into two groups according to the location of the antigen: inside the neuron or in the cell membrane. Group I includes antibodies which target intracellular antigens and probably are not pathogenic. They are further subdivided into three groups. Group Ia comprises well-characterized onconeural antibodies (Hu (ANNA1), Yo (PCA1), Ri (ANNA2), CV2 (CRMP5), amphiphysin, Ma2) that are useful for the diagnosis of PNS. Group Ib antibodies (SOX and ZIC) are cancer-specific but there is no evidence that the immune response is in any way pathogenically related to the PNS. Antibodies in group Ic (glutamic acid decarboxylase (GAD), adenylate kinase 5 and Homer 3) identify non-PNS: stiff-person syndrome (SPS), cerebellar ataxia, and limbic encephalitis (LE). Group II antibodies recognize neuronal surface antigens. Antibodies in group IIa associate with characteristic CNS syndromes but their detection does not indicate that the disorder is paraneoplastic. Antibodies to potassium channels, AMPA and GABAB receptors are associated with LE, NMDA receptor antibodies identify a well-defined encephalitis, and antibodies against glycine receptors associate with SPS with encephalitis. A pathogenic role of the antibodies is suggested by the response of symptoms to immunotherapy and the correlation between antibody titers and neurological outcome. Lastly, Group IIb includes antibodies that are found in patients with paraneoplastic cerebellar ataxia associated with lung cancer (P/Q type calcium channels antibodies) or Hodgkin disease (metabotropic glutamate receptor type 1 antibodies).

Investigations of Caspr2, an autoantigen of encephalitis and neuromyotonia

To report clinical and immunological investigations of contactin‐associated protein‐like 2 (Caspr2), an autoantigen of encephalitis and peripheral nerve hyperexcitability (PNH) previously attributed to voltage‐gated potassium channels (VGKC).

Selective expression of Purkinje-cell antigens in tumor tissue from patients with paraneoplastic cerebellar degeneration.

Abstract Paraneoplastic cerebellar degeneration is a rare syndrome that occurs in patients with gynecologic cancer and is characterized by widespread loss of Purkinje cells. To determine whether Purkinje-cell antigens are selectively expressed in the tumors of patients with the syndrome, we examined tumor tissue from 10 patients whose serum contained anti—Purkinje-cell (anti-Yo) antibodies. The origins of the cancers were the breast (five patients), ovary (three), endometrium (one), and fallopian tube (one). We used as controls tumor tissue from 11 patients with ovarian cancer and 10 patients with breast cancer who were neurologically normal. Using immunohistochemical and Western blot analysis, we found that Purkinje-cell antigens were expressed in all the tumors from the 10 patients with paraneoplastic cerebellar degeneration but in none of the tumors from the 21 neurologically normal patients. When IgG from patients with paraneoplastic cerebellar degeneration was affinity-purified to cerebellar Purkinje...

Screening for tumours in paraneoplastic syndromes: report of an EFNS Task Force

Background:  Paraneoplastic neurological syndromes (PNS) almost invariably predate detection of the malignancy. Screening for tumours is important in PNS as the tumour directly affects prognosis and treatment and should be performed as soon as possible.

Hematopoietic stem cell transplantation for multiple sclerosis

Rationale Phase I/II studies of autologous hematopoietic stem cell transplantation (HSCT) for multiple sclerosis (MS) were initiated, based on results of experimental transplantation in animal models of multiple sclerosis and clinical observations in patients treated concomitantly for malignant disease. Patients Eighty-five patients with progressive MS were treated with autologous HSCT in 20 centers and reported to the autoimmune disease working party of the European Group for Blood and Marrow Transplantation (EBMT). 52 (61 %) were female, median age was 39 [20-58] years. The median interval from diagnosis to transplant was 7 [1-26] years. Patients suffered from severe disease with a median EDSS score of 6.5 [4.5-8.5]. Active disease prior to transplant was documented in 79 of 82 evaluable cases. Results The stem cell source was bone marrow in 6 and peripheral blood in 79, and stem cells were mobilized into peripheral blood using either cyclophosphamide combined with growth factors or growth factors alone. Three patients experienced transient neurological complications during the mobilization phase. The high dose regimen included combination chemotherapy, with or without anti-lymphocyte antibodies or, with or without, total body irradiation. The stem cell transplants were purged of lymphocytes in 52 patients. Median follow-up was 16 [3-59] months. There were 7 deaths, 5 due to toxicity and infectious complications, 2 with neurological deterioration. The risk of death of any cause at 3 years was 10 (±7)% (95 % confidence interval). Neurological deterioration during transplant was observed in 22 patients; this was transient in most but was associated with MS progression in 6 patients. Neurological improvement by ≥ 1 point in the EDSS score was seen in 18 (21 %) patients. Confirmed progression-free survival was 74 (±12)% at 3 years being 66 (±23)% in patients with primary progressive MS but higher in patients with secondary progressive or relapsing-remitting MS, 78 (±13)%; p = 0.59. The probability of confirmed disease progression was 20 (±11)%. MRI data were available in 78 patients before transplant showing disease activity (gadolinium enhancing, new or enlarging lesions) in 33 %. Posttransplant MRI showed activity at any time in 5/61 (8 %) evaluable cases. Conclusion Autologous HSCT suggest positive early results in the management of progressive MS and is feasible. These multicentre data suggest an association with significant mortality risks especially in some patient groups and are being utilised in the planning of future trials to reduce transplant related mortality.