Onconeural Antibodies and Limbic Encephalitis

Transcription

1 Onconeural Antibodies and Limbic Encephalitis Type 1 : Classic paraneoplastic neurological disease presentations Typical clinical syndromes: Limbic encephalitis Encephalomyelitis Subacute cerebellar degeneration Opsoclonus Myoclonus Retinopathy Stiff Person syndrome Features of Type 1 : Tumour often sub- clinical Syndrome can precede cancer diagnosis by up to 5 years Aggressive course often respond poorly to treatment Cytotoxic T cell response- mediated Intracellular antigens antibodies occur as an epiphenomenon Type 2 : Autoimmune encephalitis More common than paraneoplastic syndromes Autoantibodies directed against cell surface or synaptic receptors Methods of Autoantibody Detection: Indirect immunofluorescence: o Primate or rodent brain o Transfected cell line (HEK293) single antigen o Encephalitis chip composite slide of NMDA, AMPA, GABA, LGI1, CASPR2 transfected HEK293 cells.

2 Radioimmunoassay (VGKC and VGCC) Neuronal immunoblot (applied as supplementary step or if IIF is uninterpretable) ELISA (GAD) Pitfalls in antineuronal antibody detection: Use of serum vs CSF. Serum sufficient for some testing (e.g onconeural antibodies) but often not for others (e.g NMDA). Unable to perform RIA on CSF for VGKC (do LGI1/CASPR2 instead less sensitive) Poor standardization of methods and testing algorithms. No consensus reporting guidelines Differences between substrates (i.e primate vs rodent) Cost multistep testing process and supplementary methods the MBS often doesn t cover the cost of further testing Screening dilution and endpoint titration (not possible with transfected cell lines subjectively compare fluorescence of sequential samples instead) Lack of reference sera and positive controls Significance of atypical IIF patterns with negative immunoblot Interpretation of neuronal immunoblot in the setting of uninterpretable IIF (i.e due to presence of an ANA). Seronegative samples with high pre- test probability. Need for collaboration with other laboratories.

3 IIF localization (from Ramnani N, Nat Rev Neuroscience 2006;7:511-22) (White matter at lower right corner of this diagram)

4 Onconeural/intra- neuronal antibodies: Antibody Target Clinical Syndrome Associations Detection methods/appearance ANNA- 1/Hu ANNA- 2/Ri Family of nuclear proteins thought to regulate cell cycle in early development RNA binding protein PCA- 1/Yo CDR 1&2 (cerebellar deneration protein 1 &2 PCA- 2 PCA- Tr DNER, a transmembrane protein that is preferentially expressed in the dendrites of Purkinje cells and likely plays a regulatory role in dendrite patterning Limbic encephalitis 50% Sensorimotor/autonomic neuropathy Cerebellar ataxia Gastrointestinal dysmotility Cerebellar degeneration Encephalomyelitis Opsoclonus- myoclonus Cerebellar degeneration Limbic encephalitis Cerebellar degeneration Neuropathy SCLC (80%) Neuroblastoma, prostate, rhabdosarcoma, gall bladder CA SCLC Gynaecological tumours Ovarian cancer Breast cancer Gynaecological tumours SCLC IIF on neuronal tissue Staining of neuronal nuclei granular/molecular/purkinje cells Myenteric plexus staining Nucleoli spared Purkinje cells look like a fried egg with a bubble in the yolk Similar to ANNA- 1 without myenteric plexus staining Purkinje cell granular cytoplasmic staining Purkinje cell cytoplasmic staining that extends into dendrites Myenteric plexus staining Paraneoplastic cerebellar degeneration Hodgkin lymphoma Staining of Purkinje cell cytoplasm and dendrites. Punctate pattern of staining in molecular layer distinguishes from PCA- 1/2

5 Ma2 Ma1(Ta) CV2/CRMP- 5 Collapsin- reponse mediator brain protein Ma2: Brainstem and limbic encephalitis, cerebellitis Ma1: Brainstem/cerebellar syndrome Optic neuritis Sensory neuropathy Encephalomyelitis Cerebellitis Ma2: Germ cell tumours, testicular tumours Ma1: Various SCLC Thymoma Often co- exists with ANNA- 1 Binds neuronal nuclei of molecular layer and Purkinje cells (need to exclude nucleolar ANA as produces a similar pattern) (Ma1 stains testis) Sand- like fluorescence on cerebellum, most visible in the molecular layer, cytoplasm of oligodendrocytes in white matter Difficult to detect by IIF Sox- 1/AGNA GAD Glutamic acid decarboxylase (2 MWs 65/67kDa) Amphiphysin Amphiphysin (128 kda dimeric, synaptic protein) is found in cerebellar presynaptic nerve terminals. Sensory neuropathy Limbic encephalitis LEMS Cerebellar degeneration Stiff person syndrome Limbic encephalitis Seizures Cerebellitis (often in association with stiff person syndrome) Stiff person syndrome Encephalomyelitis Cerebellar syndrome SCLC Often co- exists with ANNA- 1 Paraneoplastic LE in SCLC and thymoma SCLC Breast cancer May coexist with other antibodies Stains nuclei of Bergmann glia cells in Purkinje cell layer Staining my be obscured by concurrent ANNA- 1 Stains between cell bodies of granular layer cobblestone appearance Basket cells adjacent to Purkinje cells ELISA usually high values for LE, seizures, lower values for SPS Diabetic GAD doesn t usually cause IIF pattern GAD- like with strong molecular layer wash

6 Cell- surface antibodies/other: Antibody Target Clinical Syndrome Associations Detection methods/appearance NMDA- R NR1 subunit of NMDA- R (excitatory neurotransmitter) Disruption of receptor function, cross- linking/internalisation Infancy elderly, frequently 2 40 years.up to 80% female. Behavioural disturbance, psychosis, catatonia, seizures, aphasia, movement disorders including orolingual dyskinesias, central hypoventilation, dysautonomia MRI: Up to 50% abnormal; medial temporal lobe hyperintensity, focal cortical T2- weighted/flair hyperintensity Ovarian teratomas in women >18 years (45%, <9% if <14yrs), can be other tumours (thymomas, mediastinal or testicular teratomas, Hodgkin lymphoma), significant portion non- paraneoplastic (particularly children and males) Prognosis better if teratoma present Cerebellum IIF GAD- like staining Hippocampus molecular layer (neuropil) staining Transfected HEK293 cell line CSF higher specificity and sensitivity May get false positives in serum due to non- specific neuronal damage in neurodegenerative conditions CSF: 90% abnormal CSF lymphocytosis, intrathecal oligoclonal bands and elevated protein EEG: Epileptiform changes or generalized slowing VGKC complex RIA Radiolabelled dendrotoxin binds VGKC and associated proteins. Antibodies detected by immunoprecipitation May detect non- LGI1/CASPR2 anti- VGKC False positives at low values Antibodies in CNS involvement usually of higher titre than PNS involvement 80% clinically relevant VGKC +ves are LGI1 or CASPR2

7 LGI- 1 (VGKC complex) Leucine- rich glioma inactivated protein 1 Secreted synaptic protein that regulates Kv1.1 and Kv1.2 subunits years (median 60 years). 65% male. Faciobrachial dystonic seizures, hyponatraemia, limbic encephalitis, epilepsy (often tonic seizures), myoclonus, rapidly progressive dementia (can mimic CJD), sleep disorders <20% associated with malignancy (lung, thymus) RIA for anti- VGKC complex LGI- 1 transfected HEK293 cell line Sensitivity may be improved by using live transfected cell line (not commercially available) MRI: 85% medial temporal lobe FLAIR high signal CSF: 40% abnormal CASPR- 2 (VGKC complex) Contactin- associated protein- like 2 Transmembrane axonal protein that regulates Kv1 channels on myelinated axons 85% male. Peripheral nerve hyperexcitability or neuromyotonia (Isaacs syndrome), Morvan s syndrome (neuromyotonia plus cognitive impairment, sleep disturbance and dysautonomia), limbic encephalitis (less common), sleep disorders 25% abnormal, often bland CSF Thymomas in 20-40% RIA for anti- VGKC complex CASPR2 transfected HEK293 cell line MRI: 40% abnormal, medial temporal lobe FLAIR high signal AMPA- R (anti- GluR1/R2) Alfa- amino- 3- hydroxyl- 4- isoxazoleproprionic acid receptor antibodies. AMPA R is an ionotropic excitatory glutamate receptor Limbic encephalitis, atypical psychosis years 90% female CSF: 90% abnormal, often intrathecal oligoclonal bands MRI: 90% abnormal, medial temporal lobe FLAIR high signal Tumours in 70% (small cell lung cancer, breast cancer, thymic cancer) GAD- like staining on neuronal tissue AMPA- R transfected cell line

8 GABA- B GABA is the main inhibitory neurotransmitter years (median 60 years) 50% female Limbic encephalitis, prominent seizures in up to 80% of patients Tumours in 45 60% (small cell lung cancer) GAD- like staining on neuronal tissue GABA- B transfected cell line CSF: 80 90% abnormal, often intrathecal oligoclonal bands MRI: 65% medial temporal lobe FLAIR high signal GABA- A Status epilepticus, epilepsy partialis continua, rapidly progressive encephalitis Not commercially available Glycine- R Chloride channel that mediates inhibitory synaptic transmission Progressive encephalomyelitis with rigidity, stiff person syndrome (with marked startle response), seizures Reported lung cancer, Hodgkin lymphoma, thymoma; usually not paraneoplastic Can have concurrent GAD65 IgG antibodies IIF poorly defined PERM (Progressive encephalomyelitis with rigidity and myoclonus) VGCC VGCC trigger the fusion of presynaptic Ach- containing vesicles with the plasma membranes antibodies inhibit this function Lambert- Eaton Myaesthenic syndrome Proximal weakness and autonomic dysfunction SCLC (in 60%) 85-90% of patients with the syndrome are antibody positive RIA Radiolabelled omega- conotoxin binds VGCC, precipitated by antibody

9 MOG Myelin oligodendrocyte glycoprotein Expressed exclusively on CNS oligodendrocytes and myelin Aquaporin 4 Astrocytic water channel DPPX Subunit of Kv4.2 potassium channels ADEM (children) Aquaporin- 4 negative NMO/NMOSD NMO spectrum disorders Optic neuritis/transverse myelitis Hiccups/nausea/vomiting lesions at the medullar floor of 4 th ventricle and area postrema years, M:F 1:1 Protracted encephalitic illness characterised by agitation, myoclonus, tremor, seizures In comparison to AQP- 4 disease, MOG +ve are: Younger, less female predominance Prominent optic disc swelling If transverse myelitis more like to recur with optic neuritis Some studies suggest more likely to be uniphasic illness More ADEM- like lesions on MR cortical lesions, deep gray matter (bilateral thalamic and basal ganglia), cerebellum and brainstem High concurrence of autoimmunity i.e SLE, Sjogren s, thyroiditis, Coeliac disease, IBD, T1DM Prodromal diarrhoea (described in almost all patients thus far) thought to be secondary to the expression of DPPX in the myenteric plexus Confirmational epitopes are important White matter staining on neuronal IIF in some cases ELISA/Western blot poor sensitivity/specificity RIA to MOG tetramer Transfected cell line indirect immunofluorescence or flow cytometry Not commercially available Pial perivascular staining and renal papilla on rodent tissue Transfected cell line possibly more sensitive and specific than tissue +ve transfected cells with negative rodent tissue may be associated with area postrema lesions or less typical NMO presentations Sensitivity ~70-80% Highly specific IIF GAD- like staining HEK293 transfected cell line CSF lymphocytic pleocytosis ± oligoclonal bands Not associated with malignancy in case descriptions to date

10 MRI normal or nonspecific white matter disease iglon5 mglur5 Neuronal cell adhesion molecule Subtype of metabotropic glutamate receptor Chronic slow evolution. Sleep disorder (OSA, abnormal sleep movements and behaviours), bulbar involvement and dysautonomia, abnormal movements, gait instability/ataxia, central hypoventilation. Neuropathology widespread accumulation of phosphorylated tau years. Described in both men and women. Ophelia syndrome (limbic encephalitis and Hodgkin lymphoma) psychiatric symptoms, cognitive and memory impairment CSF: lymphocytic pleocytosis Antibody may occur as an epiphenomenon of a primary neurodegenerative condition Not immunotherapy responsive Hodgkin lymphoma Usually good recovery with treatment of lymphoma. Autoantibody thought to affect neuron function rather than by causing cell death Transfected cell line (not commercially available) Staining of cerebellar molecular and granular layers (mostly molecular) Rat hippocampal neuropil staining MRI features vary mesial temporal T2- weighted hyperintensity, cortical hyperintensity, and pontine hyperintensity and post- contrast enhancement have all been described mglur1 Subtype of metabotropic glutamate receptor Described in a few cases of paraneoplastic cerebellar degeneration with Hodgkin lymphoma Hodgkin lymphoma Purkinje cell staining and punctate staining of the molecular layer Transfected cell line (research only)

11 IIF Appearances (see immunology- services/neuroimmunology/neuro- antibodies/paraneoplastic- Abs.aspx ) ANNA- 1/Hu Cerebellum: Mesenteric plexus staining:

12 Luke Droney ANNA- 2/Ri Similar to appearance of ANNA- 1 without staining of the myenteric plexus PCA- 1 (NB granular layer counterstain on left)

13 PCA- 2

14 PCA- Tr GAD

15 Luke Droney

16 Ampiphysin

17 Ma

18 Luke Droney SOX- 1

19 Luke Droney CV2