Intrathecal immunoglobulin A and G antibodies to synapsin in a patient with limbic encephalitis

To report on the identification of intrathecally synthesized immunoglobulin A (IgA) and immunoglobulin G (IgG) antibodies to synapsin, a synaptic vesicle-associated protein, in a patient with limbic encephalitis

The influence of Clostridium botulinum C3 proteins on neuronal glutamate uptake

Einleitung: Nach Rückenmarkstraumata kann die neuronale Regeneration durch Clostridium botulinum C3 Exoenzym (C3bot) und C3bot 26mer (ein von C3bot abgeleitetes Peptid) gefördert werden. Besondere Aufmerksamkeit gilt dabei C3bot 26mer, da es auch ohne enzymatische Aktivität weiterhin neuroregenerativ wirkt. In dieser Arbeit wurden die Effekte von C3bot und C3bot 26mer auf die neuronale EAAT3-vermittelte Glutamat-Aufnahme in der hippocampalen Zelllinie HT22 und in primären Hippocampus-Kulturen der Maus untersucht. Methodik: HT22 Zellen und primäre hippocampale Neurone wurden drei Tage mit C3bot bzw. C3bot 26mer behandelt, bevor die [3H]-Glutamat-Aufnahme-Kapazität als Maß der Glutamat-Aufnahme aus dem Extrazellulärraum analysiert wurde. Immunfluoreszenz-, Western Blot und PCR- Analysen, sowie Biotinylierungs- und Immunpräzipitations-Studien dienten der Frage nach Ursachen veränderter Glutamat-Aufnahme-Kapazitäten unter C3 Proteinen. Ergebnisse: C3bot 26mer führt zu einer verstärkten EAAT3-vermittelten Glutamat-Aufnahme in Hippocampusneuronen. Dieser Effekt beruht auf einer gesteigerten Phosphorylierung des Plasmamembran-ständigen Glutamattransporters EAAT3. Umgekehrt konnte bei der HT22 Zelllinie beobachtet werden: Eine reduzierte EAAT3-vermittelte Glutamat-Aufnahme ging mit einer reduzierten Phosphorylierung des Transporters und einem reduzierten Gehalt an EAAT3-mRNA einher. Des weiteren ließ sich feststellen, dass die beiden Zellkultursysteme Unterschiede in der Sensibilität gegenüber enzymkompetentem C3bot und enzymdefizientem C3bot 26mer zeigten: Während C3bot 26mer die Glutamat-Aufnahme-Kapazität in beiden Zelltypen beeinflusste, hatte es keine Wirkung auf Zellmorphologie und RhoA-Aktivität der HT22 Zelllinie. Schlussfolgerung: Clostridium botulinum C3 Proteine könnten neben ihrem positiven Effekt auf das axonale Fortsatzwachstum auch durch Verstärkung der neuronalen Glutamat-Aufnahme-Kapazität die neuronale Regenerationsfähigkeit positiv beeinflussen. Beide Eigenschaften machen C3 Proteine zu vielversprechenden Werkzeugen in der Behandlung zentralnervöser Traumata.Introduction: Clostridium botulinum C3 exoenzyme (C3bot) and C3bot 26mer (a C3bot-derived peptide) promote neuronal regeneration after spinal cord injury. Particular attention is paid to C3bot 26mer which, although lacking enzymatic activity, still promotes neuroregeneration. The present study investigates the effects of C3bot and C3bot 26mer on neuronal EAAT3-mediated glutamate uptake in the hippocampal cell line HT22 and in mouse primary hippocampal cultures. Methods: HT22 cells and primary hippocampal neurons were treated with C3bot and C3bot 26mer for three days prior to analysis of [3H] -glutamate uptake capacity. Immunofluorescence, Western Blot, and PCR analyzes as well as biotinylation and immunoprecipitation studies were used to investigate the causes of altered glutamate uptake capacities after treatment with C3 proteins. Results: This study shows that C3bot and C3bot 26mer increase phosphorylation of the glutamate transporter EAAT3 located in the plasmamembrane which mediates an increased EAAT3-mediated glutamate uptake in hippocampal neurons. Vice-versa we could observe a reduced EAAT3-mediated glutamate uptake accompanied by reduced transporter phosphorylation and reduced levels of EAAT3 mRNA in the HT22 cell line. Furthermore, the two cell culture systems showed differences in sensitivity to enzyme-competent C3bot and enzyme-deficient C3bot 26mer: while C3bot 26mer affected glutamate uptake capacity in both cell types, this peptide had no effect on cell morphology and activity of RhoA in the HT22 cell line. Conclusion: Next to the known promoting of axonal outgrowth, Clostridium botulinum C3 proteins also could facilitate neuronal regeneration by enhancing glutamate uptake capacity of primary neurons. These properties make C3 Proteins promising tools for the treatment of lesions of the central nervous system

Epitope specificity of anti-synapsin autoantibodies: Differential targeting of synapsin I domains.

OBJECTIVE:To identify the specific domains of the presynaptic protein synapsin targeted by recently described autoantibodies to synapsin. METHODS:Sera of 20 and CSF of two patients with different psychiatric and neurological disorders previously tested positive for immunoglobulin (Ig)G antibodies to full-length synapsin were screened for IgG against synapsin I domains using HEK293 cells transfected with constructs encoding different domains of rat synapsin Ia. Additionally, IgG subclasses were determined using full-length synapsin Ia. Serum and CSF from one patient were also screened for IgA autoantibodies to synapsin I domains. Sera from nine and CSF from two healthy subjects were analyzed as controls. RESULTS:IgG in serum from 12 of 20 IgG synapsin full-length positive patients, but from none of the healthy controls, bound to synapsin domains. Of these 12 sera, six bound to the A domain, five to the D domain, and one to the B- (and possibly A-), D-, and E-domains of synapsin I. IgG antibodies to the D-domain were also detected in one of the CSF samples. Determination of IgG subclasses detected IgG1 in two sera and one CSF, IgG2 in none of the samples, IgG3 in two sera, and IgG4 in eight sera. One patient known to be positive for IgA antibodies to full-length synapsin had IgA antibodies to the D-domain in serum and CSF. CONCLUSIONS:Anti-synapsin autoantibodies preferentially bind to either the A- or the D-domain of synapsin I

Sunlight exposure exerts immunomodulatory effects to reduce multiple sclerosis severity

Multiple sclerosis (MS) disease risk is associated with reduced sunexposure. This study assessed the relationship between measures of sun exposure (vitamin D [vitD], latitude) and MS severity in the setting of two multicenter cohort studies (n(NationMS) = 946, n(BIONAT) = 990). Additionally, effect-modification by medication and photosensitivity-associated MC1R variants was assessed. High serum vitD was associated with a reduced MS severity score (MSSS), reduced risk for relapses, and lower disability accumulation over time. Low latitude was associated with higher vitD, lower MSSS, fewer gadolinium-enhancing lesions, and lower disability accumulation. The association of latitude with disability was lacking in IFN-beta-treated patients. In carriers of MC1R:rs1805008(T), who reported increased sensitivity toward sunlight, lower latitude was associated with higher MRI activity, whereas for noncarriers there was less MRI activity at lower latitudes. In a further exploratory approach, the effect of ultraviolet (UV)-phototherapy on the transcriptome of immune cells of MS patients was assessed using samples from an earlier study. Phototherapy induced a vitD and type I IFN signature that was most apparent in monocytes but that could also be detected in B and T cells. In summary, our study suggests benefidal effects of sun exposure on established MS, as demonstrated by a correlative network between the three factors: Latitude, vitD, and disease severity. However, sun exposure might be detrimental for photosensitive patients. Furthermore, a direct induction of type I IFNs through sun exposure could be another mechanism of UV-mediated immune-modulation in MS

Genome-wide Association Study Identifies 2 New Loci Associated With Anti-NMDAR Encephalitis

Background and Objectives To investigate the genetic determinants of the most common type of antibody-mediated autoimmune encephalitis, anti-NMDA receptor (anti-NMDAR) encephalitis. Methods We performed a genome-wide association study in 178 patients with anti-NMDAR encephalitis and 590 healthy controls, followed by a colocalization analysis to identify putatively causal genes. Results We identified 2 independent risk loci harboring genome-wide significant variants (p = 2.2), 1 on chromosome 15, harboring only the LRRK1 gene, and 1 on chromosome 11 centered on the ACP2 and NR1H3 genes in a larger region of high linkage disequilibrium. Colocalization signals with expression quantitative trait loci for different brain regions and immune cell types suggested ACP2, NR1H3, MADD, DDB2, and C11orf49 as putatively causal genes. The best candidate genes in each region are LRRK1, encoding leucine-rich repeat kinase 1, a protein involved in B-cell development, and NR1H3 liver X receptor alpha, a transcription factor whose activation inhibits inflammatory processes. Discussion This study provides evidence for relevant genetic determinants of antibody-mediated autoimmune encephalitides outside the human leukocyte antigen (HLA) region. The results suggest that future studies with larger sample sizes will successfully identify additional genetic determinants and contribute to the elucidation of the pathomechanism