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Antibodies to the inositol 1,4,5-trisphosphate receptor type 1 (ITPR1) in cerebellar ataxia.

Jarius S, Scharf M, Begemann N, Stöcker W, Probst C, Serysheva II, Nagel S, Graus F, Psimaras D, Wildemann B, Komorowski L - J Neuroinflammation (2014)

Bottom Line: The antibody bound to PC somata, dendrites, and axons, resulting in a binding pattern similar to that reported for anti-Ca/anti-ARHGAP26, but did not react with recombinant ARHGAP26.By contrast, anti-ARHGAP26-positive sera did not bind to ITPR1.Our findings suggest a role of autoimmunity against ITPR1 in the pathogenesis of autoimmune cerebellitis and extend the panel of diagnostic markers for this disease.

View Article: PubMed Central - PubMed

Affiliation: Molecular Neuroimmunology, Department of Neurology, University of Heidelberg, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany. sven.jarius@med.uni-heidelberg.de.

ABSTRACT
We report on a serum autoantibody associated with cerebellar ataxia. Immunohistochemical studies of sera from four patients referred for autoantibody testing revealed binding of high-titer (up to 1:5,000) IgG antibodies, mainly IgG1, to the molecular layer, Purkinje cell layer, and white matter on mouse, rat, porcine, and monkey cerebellum sections. The antibody bound to PC somata, dendrites, and axons, resulting in a binding pattern similar to that reported for anti-Ca/anti-ARHGAP26, but did not react with recombinant ARHGAP26. Extensive control studies were performed to rule out a broad panel of previously described paraneoplastic and non-paraneoplastic anti-neural autoantibodies. The characteristic binding pattern as well as double staining experiments suggested inositol 1,4,5-trisphosphate receptor type 1 (ITPR1) as the target antigen. Verification of the antigen included specific neutralization of the tissue reaction following preadsorption with ITPR1 (but not ARHGAP26) and a dot-blot assay with purified ITPR1 protein. By contrast, anti-ARHGAP26-positive sera did not bind to ITPR1. In a parallel approach, a combination of histoimmunoprecipitation and mass spectrometry also identified ITPR1 as the target antigen. Finally, a recombinant cell-based immunofluorescence assay using HEK293 cells expressing ITPR1 and ARHGAP26, respectively, confirmed the identification of ITPR1. Mutations of ITPR1 have previously been implicated in spinocerebellar ataxia with and without cognitive decline. Our findings suggest a role of autoimmunity against ITPR1 in the pathogenesis of autoimmune cerebellitis and extend the panel of diagnostic markers for this disease.

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Related in: MedlinePlus

Binding of patient IgG to the Purkinje cell (PC) dendrites (PCD) in the molecular layer (ML), to the PC somata in the PC layer (PCL), and to the PC axons (PCA) in the white matter (WM) on murine cerebellum tissue sections. The observed staining pattern (A) is similar to that observed with anti-Ca/ARHGAP26 (see reference [30]). Note that PC nuclei, interneurons, and granular cells are spared. Also note that the PCD (B and C) and the PCA (D and E) staining patterns can differ significantly depending on sectional planes. Axonal staining may not be detectable on all sections. GL, Granular cell layer.
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Fig1: Binding of patient IgG to the Purkinje cell (PC) dendrites (PCD) in the molecular layer (ML), to the PC somata in the PC layer (PCL), and to the PC axons (PCA) in the white matter (WM) on murine cerebellum tissue sections. The observed staining pattern (A) is similar to that observed with anti-Ca/ARHGAP26 (see reference [30]). Note that PC nuclei, interneurons, and granular cells are spared. Also note that the PCD (B and C) and the PCA (D and E) staining patterns can differ significantly depending on sectional planes. Axonal staining may not be detectable on all sections. GL, Granular cell layer.

Mentions: Immunohistochemistry on formalin-fixed frozen adult mouse, rat, and monkey tissue sections demonstrated strong reactivity of serum to structures in the molecular layer (ML), the Purkinje cell layer (PCL), and the white matter (WM) of the cerebellum (Figure 1), similar to that of anti-Ca/ARHGAP26 [30-32]. More detailed analysis at higher magnification revealed binding of IgG to somata, dendritic trunks, dendritic branches, and possibly dendritic spines of PCs, as previously described for anti-ARHGAP26 (anti-Ca). In addition, axons in the WM were stained by the patients’ serum. Double labeling with anti-GFAP and anti-AQP4 revealed no binding of the patient antibody to astrocytes in the WM and the granular layer (GL), or to Bergman glial cells in the PCL and ML (not shown). As anti-Ca/ARHGAP26, the antibodies spared interneurons, such as stellate cells, basket cells, and Golgi cells, as well as granular cells. The antibody stained PC somata and PC axons more intensely than anti-Ca/ARHGAP26-positive sera in a direct comparison, equaling the fluorescence intensity of the molecular layer. Interestingly, using primate enteric tissue sections, no binding to the plexus myentericus was observed, but there was strong staining of both the circular and the longitudinal tunica muscularis as well as of the muscularis propria and of blood vessel-related muscle cells, in addition to a fine, linear fluorescence adjacent to the epithelium of the intestinal villi. No such fluorescence was detected with anti-ARHGAP26-positive sera, which stained the myenteric plexus but not the muscle layers. Of note, enteric tissue sections have been previously used to differentiate between anti-Hu and anti-Ri antibodies, two anti-neuronal antibodies that are otherwise difficult to distinguish. We decided to refer to the specific staining pattern described here as anti-Sj throughout the manuscript, following a widely accepted convention to name newly described antibodies with reference to the index sample’s initials or code.Figure 1


Antibodies to the inositol 1,4,5-trisphosphate receptor type 1 (ITPR1) in cerebellar ataxia.

Jarius S, Scharf M, Begemann N, Stöcker W, Probst C, Serysheva II, Nagel S, Graus F, Psimaras D, Wildemann B, Komorowski L - J Neuroinflammation (2014)

Binding of patient IgG to the Purkinje cell (PC) dendrites (PCD) in the molecular layer (ML), to the PC somata in the PC layer (PCL), and to the PC axons (PCA) in the white matter (WM) on murine cerebellum tissue sections. The observed staining pattern (A) is similar to that observed with anti-Ca/ARHGAP26 (see reference [30]). Note that PC nuclei, interneurons, and granular cells are spared. Also note that the PCD (B and C) and the PCA (D and E) staining patterns can differ significantly depending on sectional planes. Axonal staining may not be detectable on all sections. GL, Granular cell layer.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4300617&req=5

Fig1: Binding of patient IgG to the Purkinje cell (PC) dendrites (PCD) in the molecular layer (ML), to the PC somata in the PC layer (PCL), and to the PC axons (PCA) in the white matter (WM) on murine cerebellum tissue sections. The observed staining pattern (A) is similar to that observed with anti-Ca/ARHGAP26 (see reference [30]). Note that PC nuclei, interneurons, and granular cells are spared. Also note that the PCD (B and C) and the PCA (D and E) staining patterns can differ significantly depending on sectional planes. Axonal staining may not be detectable on all sections. GL, Granular cell layer.
Mentions: Immunohistochemistry on formalin-fixed frozen adult mouse, rat, and monkey tissue sections demonstrated strong reactivity of serum to structures in the molecular layer (ML), the Purkinje cell layer (PCL), and the white matter (WM) of the cerebellum (Figure 1), similar to that of anti-Ca/ARHGAP26 [30-32]. More detailed analysis at higher magnification revealed binding of IgG to somata, dendritic trunks, dendritic branches, and possibly dendritic spines of PCs, as previously described for anti-ARHGAP26 (anti-Ca). In addition, axons in the WM were stained by the patients’ serum. Double labeling with anti-GFAP and anti-AQP4 revealed no binding of the patient antibody to astrocytes in the WM and the granular layer (GL), or to Bergman glial cells in the PCL and ML (not shown). As anti-Ca/ARHGAP26, the antibodies spared interneurons, such as stellate cells, basket cells, and Golgi cells, as well as granular cells. The antibody stained PC somata and PC axons more intensely than anti-Ca/ARHGAP26-positive sera in a direct comparison, equaling the fluorescence intensity of the molecular layer. Interestingly, using primate enteric tissue sections, no binding to the plexus myentericus was observed, but there was strong staining of both the circular and the longitudinal tunica muscularis as well as of the muscularis propria and of blood vessel-related muscle cells, in addition to a fine, linear fluorescence adjacent to the epithelium of the intestinal villi. No such fluorescence was detected with anti-ARHGAP26-positive sera, which stained the myenteric plexus but not the muscle layers. Of note, enteric tissue sections have been previously used to differentiate between anti-Hu and anti-Ri antibodies, two anti-neuronal antibodies that are otherwise difficult to distinguish. We decided to refer to the specific staining pattern described here as anti-Sj throughout the manuscript, following a widely accepted convention to name newly described antibodies with reference to the index sample’s initials or code.Figure 1

Bottom Line: The antibody bound to PC somata, dendrites, and axons, resulting in a binding pattern similar to that reported for anti-Ca/anti-ARHGAP26, but did not react with recombinant ARHGAP26.By contrast, anti-ARHGAP26-positive sera did not bind to ITPR1.Our findings suggest a role of autoimmunity against ITPR1 in the pathogenesis of autoimmune cerebellitis and extend the panel of diagnostic markers for this disease.

View Article: PubMed Central - PubMed

Affiliation: Molecular Neuroimmunology, Department of Neurology, University of Heidelberg, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany. sven.jarius@med.uni-heidelberg.de.

ABSTRACT
We report on a serum autoantibody associated with cerebellar ataxia. Immunohistochemical studies of sera from four patients referred for autoantibody testing revealed binding of high-titer (up to 1:5,000) IgG antibodies, mainly IgG1, to the molecular layer, Purkinje cell layer, and white matter on mouse, rat, porcine, and monkey cerebellum sections. The antibody bound to PC somata, dendrites, and axons, resulting in a binding pattern similar to that reported for anti-Ca/anti-ARHGAP26, but did not react with recombinant ARHGAP26. Extensive control studies were performed to rule out a broad panel of previously described paraneoplastic and non-paraneoplastic anti-neural autoantibodies. The characteristic binding pattern as well as double staining experiments suggested inositol 1,4,5-trisphosphate receptor type 1 (ITPR1) as the target antigen. Verification of the antigen included specific neutralization of the tissue reaction following preadsorption with ITPR1 (but not ARHGAP26) and a dot-blot assay with purified ITPR1 protein. By contrast, anti-ARHGAP26-positive sera did not bind to ITPR1. In a parallel approach, a combination of histoimmunoprecipitation and mass spectrometry also identified ITPR1 as the target antigen. Finally, a recombinant cell-based immunofluorescence assay using HEK293 cells expressing ITPR1 and ARHGAP26, respectively, confirmed the identification of ITPR1. Mutations of ITPR1 have previously been implicated in spinocerebellar ataxia with and without cognitive decline. Our findings suggest a role of autoimmunity against ITPR1 in the pathogenesis of autoimmune cerebellitis and extend the panel of diagnostic markers for this disease.

Show MeSH
Related in: MedlinePlus