A novel mouse model for investigating α-synuclein aggregates in oligodendrocytes: implications for the glial cytoplasmic inclusions in multiple system atrophy.

The aggregated alpha-synuclein (αsyn) in oligodendrocytes (OLGs) is one of the pathological hallmarks in multiple system atrophy (MSA). We have previously reported that αsyn accumulates not only in neurons but also in OLGs long after the administration of αsyn preformed fibrils (PFFs) in mice. However, detailed spatial and temporal analysis of oligodendroglial αsyn aggregates was technically difficult due to the background neuronal αsyn aggregates. The aim of this study is to create a novel mouse that easily enables sensitive and specific detection of αsyn aggregates in OLGs and the comparable analysis of the cellular tropism of αsyn aggregates in MSA brains. To this end, we generated transgenic (Tg) mice expressing human αsyn-green fluorescent protein (GFP) fusion proteins in OLGs under the control of the 2', 3'-cyclic nucleotide 3'-phosphodiesterase (CNP) promoter (CNP-SNCAGFP Tg mice). Injection of αsyn PFFs in these mice induced distinct GFP-positive aggregates in the processes of OLGs as early as one month post-inoculation (mpi), and their number and size increased in a centripetal manner. Moreover, MSA-brain homogenates (BH) induced significantly more oligodendroglial αsyn aggregates than neuronal αsyn aggregates compared to DLB-BH in CNP-SNCAGFP Tg mice, suggestive of their potential tropism of αsyn seeds for OLGs. In conclusion, CNP-SNCAGFP Tg mice are useful for studying the development and tropism of αsyn aggregates in OLGs and could contribute to the development of therapeutics targeting αsyn aggregates in OLGs.

A RaPID Macrocyclic Peptide That Inhibits the Formation of α-Synuclein Amyloid Fibrils.

There is considerable interest in drug discovery targeting the aggregation of α-synuclein (αSyn) since this molecular process is closely associated with Parkinson's disease. However, inhibiting αSyn aggregation remains a major challenge because of its highly dynamic nature which makes it difficult to form a stable binding complex with a drug molecule. Here, by exploiting Random non-standard Peptides Integrated Discovery (RaPID) system, we identified a macrocyclic peptide, BD1, that could interact with immobilized αSyn and inhibit the formation of fibrils. Furthermore, improving the solubility of BD1 suppresses the co-aggregation with αSyn fibrils while it kinetically inhibits more effectively without change in their morphology. We also revealed the molecular mechanism of kinetic inhibition, where peptides bind to fibril ends of αSyn, thereby preventing further growth of fibrils. These results suggest that our approach for generating non-standard macrocyclic peptides is a promising approach for developing potential therapeutics against neurodegeneration.

Rheumatoid meningitis developed in patient with stable rheumatoid arthritis and myasthenia gravis-detailed analysis of intracranial inflammation using flow cytometry.

BACKGROUND: Rheumatoid meningitis (RM) is a rare disorder that often develops during a remission phase of rheumatoid arthritis (RA). This is the first study to demonstrate differences in regard to immunological disturbance between blood and cerebrospinal fluid (CSF) samples obtained from a patient with RM using flow cytometry. CASE PRESENTATION: A 36-year-old woman with RA and generalized myasthenia gravis (MG) developed RM during a remission phase. Although both RA and MG were stable and well controlled, she noticed fever, headache, and transient sensory disturbance. Blood and CSF examination findings suggested aseptic meningitis, while brain magnetic resonance imaging revealed restricted portions of meningitis and associated cortical lesions, compatible with a diagnosis of RM. The dose of oral prednisolone was increased, which ameliorated the symptoms within 1 week along with improvement in CSF findings. This patient exhibited features of RM that were manifested in a manner independent of the activity of RA. An investigation of cellular immunity using CSF specimens with flow cytometry showed differences in regard to the pathogenesis of inflammation in the CSF as compared to outside of the central nervous system. In contrast to results obtained with paired blood samples, CSF cells at the peak stage of RM showed a marked increase in CCR3+ Th2 cells and marked decrease in CD8+ cells, suggesting an immunoregulatory disturbance in the CSF. Those findings indicated a CSF-specific activation of humoral immunity, resulting in augmentation of meningeal inflammation, as shown by excess synthesis of intrathecal IgG and markedly elevated interleukin-6 level. Results of the present detailed investigation of lymphocyte subsets revealed a discrepancy regarding the process of inflammation in this RM patient between CSF and blood samples. CONCLUSIONS: RM is not a simple reflection of the immune status of RA, as the pathogenesis seems related to, at least in part, CSF-specific immunological dysregulation.

Transglutaminase 2 accelerates neuroinflammation in amyotrophic lateral sclerosis through interaction with misfolded superoxide dismutase 1.

Although the aberrant assembly of mutant superoxide dismutase 1 (mSOD1) is implicated in the pathogenesis of familial amyotrophic lateral sclerosis (ALS), the molecular basis of superoxide dismutase 1 (SOD1) oligomerization remains undetermined. We investigated the roles of transglutaminase 2 (TG2), an endogenous cross-linker in mSOD1-linked ALS. TG2 interacted preferentially with mSOD1 and promoted its oligomerization in transfected cells. Purified TG2 directly oligomerized recombinant mutant SOD1 and the apo-form of the wild-type SOD1 proteins in a calcium-dependent manner, indicating that misfolded SOD1 is a substrate of TG2. Moreover, the non-cell-autonomous effect of extracellular TG2 on the neuroinflammation was suggested, since the TG2-mediated soluble SOD1 oligomers induced tumor necrosis factor-α, interleukin-1ß, and nitric oxide in microglial BV2 cells. TG2 was up-regulated in the spinal cord of pre-symptomatic G93A SOD1 transgenic mice and in the hypoglossal nuclei of mice suffering nerve ligation. Furthermore, inhibition of spinal TG2 by cystamine significantly delayed the progression and reduced SOD1 oligomers and microglial activation. These results indicate a novel role of TG2 in SOD1 oligomer-mediated neuroinflammation, as well as in the involvement in the intracellular aggregation of misfolded SOD1 in ALS.

Severe and prolonged ictal paresis in an elderly patient.

We report an 84-year-old female who showed a rare manifestation of epilepsy, ictal paresis, a type of simple partial seizure presenting with focal motor dysfunction. While the patient exhibited severe left hemiplegia which lasted for a week, cranial diffusion-weighted MRI demonstrated slightly high intensity in the right posterior quadrant, and electroencephalography (EEG) showed continuous epileptiform discharges located mainly in the right parieto-occipital area, strongly suggesting that the patient was in an ictal state. (99m)Tc-hexamethylpropylene amine oxime-single photon emission computed tomography (HMPAO-SPECT) showed markedly high blood perfusion in the right parieto-temporo-occipital areas. Considering the distribution of EEG epileptiform activities and HMPAO-SPECT hyperperfusion, it is most likely that the ictal paresis of our patient was associated with epileptic activities at the sensorimotor area which caused either direct or indirect activation of an inhibitory system. Careful clinical consideration of the possibility of ictal paresis is needed in elderly patients, especially in those with preexisting dementia, because paresis can be as severe as complete flaccid hemiplegia and can last as long as for a week.

Conserved acidic amino acid residues in a second RNA recognition motif regulate assembly and function of TDP-43.

Accumulating evidence suggests that pathogenic TAR DNA-binding protein (TDP)-43 fragments contain a partial RNA-recognition motif domain 2 (RRM2) in amyotrophic lateral sclerosis (ALS)/frontotemporal lobar degeneration. However, the molecular basis for how this domain links to the conformation and function of TDP-43 is unclear. Previous crystal analyses have documented that the RRM2-DNA complex dimerizes under acidic and high salt conditions, mediated by the intermolecular hydrogen bonds of Glu246-Ile249 and Asp247-Asp247. The aims of this study were to investigate the roles of Glu246 and Asp247 in the molecular assembly of RRM2 under physiological conditions, and to evaluate their potential use as markers for TDP-43 misfolding due to the aberrantly exposed dimer interface. Unexpectedly, gel filtration analyses showed that, regardless of DNA interaction, the RRM2 domain remained as a stable monomer in phosphate-buffered saline. Studies using substitution mutants revealed that Glu246 and, especially, Asp247 played a crucial role in preserving the functional RRM2 monomers. Substitution to glycine at Glu246 or Asp247 induced the formation of fibrillar oligomers of RRM2 accompanied by the loss of DNA-binding affinity, which also affected the conformation and the RNA splicing function of full-length TDP-43. A novel monoclonal antibody against peptides containing Asp247 was found to react with TDP-43 inclusions of ALS patients and mislocalized cytosolic TDP-43 in cultured cells, but not with nuclear wild-type TDP-43. Our findings indicate that Glu246 and Asp247 play pivotal roles in the proper conformation and function of TDP-43. In particular, Asp247 should be studied as a molecular target with an aberrant conformation related to TDP-43 proteinopathy.

Colocalization of 14-3-3 proteins with SOD1 in Lewy body-like hyaline inclusions in familial amyotrophic lateral sclerosis cases and the animal model.

BACKGROUND AND PURPOSE: Cu/Zn superoxide dismutase (SOD1) is a major component of Lewy body-like hyaline inclusion (LBHI) found in the postmortem tissue of SOD1-linked familial amyotrophic lateral sclerosis (FALS) patients. In our recent studies, 14-3-3 proteins have been found in the ubiquitinated inclusions inside the anterior horn cells of spinal cords with sporadic amyotrophic lateral sclerosis (ALS). To further investigate the role of 14-3-3 proteins in ALS, we performed immunohistochemical analysis of 14-3-3 proteins and compared their distributions with those of SOD1 in FALS patients and SOD1-overexpressing mice. METHODS: We examined the postmortem brains and the spinal cords of three FALS cases (A4V SOD1 mutant). Transgenic mice expressing the G93A mutant human SOD1 (mutant SOD1-Tg mice), transgenic mice expressing the wild-type human SOD1 (wild-type SOD1-Tg mice), and non-Tg wild-type mice were also subjected to the immunohistochemical analysis. RESULTS: In all the FALS patients, LBHIs were observed in the cytoplasm of the anterior horn cells, and these inclusions were immunopositive intensely for pan 14-3-3, 14-3-3ß, and 14-3-3γ. In the mutant SOD1-Tg mice, a high degree of immunoreactivity for misfolded SOD1 (C4F6) was observed in the cytoplasm, with an even greater degree of immunoreactivity present in the cytoplasmic aggregates of the anterior horn cells in the lumbar spinal cord. Furthermore, we have found increased 14-3-3ß and 14-3-3γ immunoreactivities in the mutant SOD1-Tg mice. Double immunofluorescent staining showed that C4F6 and 14-3-3 proteins were partially co-localized in the spinal cord with FALS and the mutant SOD1-Tg mice. In comparison, the wild-type SOD1-Tg and non-Tg wild-type mice showed no or faint immunoreactivity for C4F6 and 14-3-3 proteins (pan 14-3-3, 14-3-3ß, and 14-3-3γ) in any neuronal compartments. DISCUSSION: These results suggest that 14-3-3 proteins may be associated with the formation of SOD1-containing inclusions, in FALS patients and the mutant SOD1-Tg mice.

Induction of protective immunity by vaccination with wild-type apo superoxide dismutase 1 in mutant SOD1 transgenic mice.

Vaccinations targeting extracellular superoxide dismutase 1 (SOD1) mutants are beneficial in mouse models of amyotrophic lateral sclerosis (ALS). Because of its misfolded nature, wild-type nonmetallated SOD1 protein (WT-apo) may have therapeutic application for vaccination of various SOD1 mutants. We compared the effects of WT-apo to those of a G93A SOD1 vaccine in low-copy G93A SOD1 transgenic mice. Both SOD1 vaccines induced antibody against G93A SOD1 and significantly delayed disease onset compared with saline/adjuvant controls. WT-apo SOD1 significantly extended the life span of vaccinated mice. The vaccines potentiated TH2 deviation in the spinal cord as determined by the ratio of interleukin-4 to interferon-γ (IFNγ) or tumor necrosis factor and induced C1q deposition around motor neurons. Transgenic mice had abundant microglial expression of signal transducers and activators of transcription 4, an activator of transcription of IFNγ, in the spinal cord implicating IFNγ in the pathogenesis. On the other hand, the sera from G93A SOD1-vaccinated mice showed higher IFNγ or tumor necrosis factor and yielded a lower IgG1/IgG2c ratio than the sera from WT-apo-vaccinated mice. These results indicate that the TH1/TH2 milieu is affected by specific vaccinations and that antigenicity might counteract beneficial effects by enhancing TH1 immunity. Thus, because of its lower TH1 induction, WT-apo may be a therapeutic option and have broader application in ALS associated with diverse SOD1 mutations.

[Trial of rituximab in three patients with neuromyelitis optica].

Patients with relapsing neuromyelitis optica (NMO) showing contiguous long spinal cord lesions extending over three vertebral segments on the MRI and with positive anti-aquaporin 4 antibodies in sera are usually treated with glucocorticoids or azathioprine. However, some NMO patients even after adequate treatments show relapses. Rituximab (anti-CD 20) therapy has recently been reported to inhibit relapses. We used rituximab to treat three NMO patients defined by the revised NMO criteria of Wingerchuk et al, with rituximab for 2 years and 3 months (mean) at an intervals of about nine months. The annualized relapse rate for the 3 patients during the year before rituximab therapy was 4, 5, and 6, respectively, and this decreased to 3, 1, and 0 in the year after therapy. Case 1 showed three relapses after therapy: however, the symptoms and signs of each of the relapses were milder and the patient showed good responses to steroid pulse therapy. One year after therapy, relapses had disappeared in all cases (observation periods; 18, 18, and 9 months, respectively). After rituximab therapy, these NMO patients showed a decreased mean annualized relapse rate (from 5.0 to 0.6) and EDSS score (from 8.7 to 8.0) after rituximab therapy. No adverse effects were seen. We recommend rituximab therapy for NMO patients resistant to other immunosuppressive therapies such as oral glucocorticoid administration introduced after a severe relapse. However, during long term rituximab treatment, attention needs to be given to infections such as progressive multifocal leucoencephalopathy.