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Considerable data implicate the thymus as the main site of autosensitization to the acetylcholine receptor in myasthenia gravis (MG), a B-cell-mediated autoimmune disease affecting the neuromuscular junction. We recently demonstrated an active Epstein-Barr virus (EBV) infection in the thymus of MG patients, suggesting that EBV might contribute to the onset or maintenance of the autoimmune response within MG thymus, because of its ability to activate and immortalize autoreactive B cells. EBV has been reported to elicit and modulate Toll-like receptor (TLR) 7- and TLR9-mediated innate immune responses, which are known to favor B-cell dysfunction and autoimmunity. Aim of this study was to investigate whether EBV infection is associated with altered expression of TLR7 and TLR9 in MG thymus. By real-time PCR, we found that TLR7 and TLR9 mRNA levels were significantly higher in EBV-positive MG compared to EBV-negative normal thymuses. By confocal microscopy, high expression levels of TLR7 and TLR9 proteins were observed in B cells and plasma cells of MG thymic germinal centers (GCs) and lymphoid infiltrates, where the two receptors co-localized with EBV antigens. An increased frequency of Ki67-positive proliferating B cells was found in MG thymuses, where we also detected proliferating cells expressing TLR7, TLR9 and EBV antigens, thus supporting the idea that EBV-associated TLR7/9 signaling may promote abnormal B-cell activation and proliferation. Along with B cells and plasma cells, thymic epithelium, plasmacytoid dendritic cells and macrophages exhibited enhanced TLR7 and TLR9 expression in MG thymus; TLR7 was also increased in thymic myeloid dendritic cells and its transcriptional levels positively correlated with those of interferon (IFN)-β. We suggested that TLR7/9 signaling may be involved in antiviral type I IFN production and long-term inflammation in EBV-infected MG thymuses. Our overall findings indicate that EBV-driven TLR7- and TLR9-mediated innate immune responses may participate in the intra-thymic pathogenesis of MG.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder characterized by progressive motoneuron loss in the CNS. In G93A-SOD1 mice, motoneuron degeneration is associated with proliferative restorative attempts of ependymal stem progenitor cells (epSPCs), usually quiescent in the spinal cord. The aims of the study were to demonstrate that epSPCs isolated from the spinal cord of G93A-SOD1 mice express neurogenic potential in vitro, and thus gain a better understanding of epSPC neural differentiation properties. For this purpose, we compared the ability of epSPCs from asymptomatic and symptomatic G93A-SOD1 and WT SOD1 transgenic mice to proliferate and differentiate into neural cells. Compared to control cells, G93A-SOD1 epSPCs differentiated more into neurons than into astrocytes, whereas oligodendrocyte proportions were similar in the two populations. G93A-SOD1 neurons were small and astrocytes had an activated phenotype. Evaluation of microRNAs, specific for neural cell fate and cell-cycle regulation, in G93A-SOD1 epSPCs showed that miR-9, miR-124a, miR-19a and miR-19b were differentially expressed. Expression analysis of the predicted miRNA targets allowed identification of a functional network in which Hes1, Pten, Socs1, and Stat3 genes were important for controlling epSPC fate. Our findings demonstrate that G93A-SOD1 epSPCs are a source of multipotent cells that have neurogenic potential in vitro, and might be a useful tool to investigate the mechanisms of neural differentiation in relation to miRNA expression whose modulation might constitute new targeted therapeutic approaches to ALS. © 2013 Elsevier Inc.

We investigated the effect of IgG immunoadsorption (IA) on cytokine network in patients with treatment-resistant Myasthenia Gravis (MG) and Lambert-Eaton Syndrome (LEMS). We observed upregulation of interleukin (IL)-10, an anti-inflammatory and B cells growth factor, and reduction of pro-inflammatory factors such as IL-18 and IL-17, in both MG and LEMS after IA. Our observation suggests that the massive removal of antibodies might induce modifications of the cytokine balance linked to T and B cells mediated autoimmunity.

Fibrosis in Duchenne muscular dystrophy patients' muscle seems to be mediated by fibrogenic cytokines, particularly transforming growth factor-beta1. Golden retriever muscular dystrophy is a model of Duchenne dystrophy characterised by severe myopathy and muscle fibrosis. We evaluated mRNA levels and protein distribution of transforming growth factor-beta1, connective tissue growth factor and collagens in muscle of golden retriever muscular dystrophy dogs at different ages. Fibrosis occurs early in golden retriever muscular dystrophy dogs and transforming growth factor-beta1 levels tend to be high up to 60 days of age (P=0.019 at 30 days), suggesting that transforming growth factor-beta1 is involved in the early stages of fibrosis. We also found greater expression of connective tissue growth factor in golden retriever muscular dystrophy than control muscle (P=0.0065 at 30 days), suggesting involvement of this molecule in fibrosis progression. Our findings sustain the hypothesis that cytokines are actively involved in fibrosis in golden retriever muscular dystrophy, as it seems to be in humans, and confirm the utility of this model for investigating new therapeutic approaches for Duchenne dystrophy.

Rasmussen's encephalitis (RE) is a rare condition characterized by drug-resistant seizures, recurrent status epilepticus and progressive lateralized neurological deterioration. There is evidence of autoimmune involvement in the pathogenesis. We investigated the presence of anti-GluR3 antibodies against peptides A and B in patients with RE (n=11), partial and generalized epilepsy (n=85) and other neurological diseases (n=30). The antibodies were specific for epilepsy and are thus not a marker of RE, while particularly high antibody titers characterized a subgroup of non-RE patients with "catastrophic" epilepsy. Antibodies against GluR3B peptide were significantly associated with frequent seizures compared to occasional or drug-controlled seizures.

Muscle or thymic myoid cells, if induced to express MHC class II in addition to endogenous acetylcholine receptor (AChR), might present epitopes derived from the AChR to specific CD4+ T cells. These T cells could in turn initiate or maintain the anti-AChR response that is responsible for AChR loss in myasthenia gravis (MG). We transfected the AChR+ TE671 (rhabdomyosarcoma) cells with HLA-DR4 and co-cultured them with the DR4-restricted, CD4+ T cell clone (PM-A1; raised from a hyperplastic thymus of an MG patient and previously shown to recognise all forms of the AChR that contain the sequence alpha 144-156). Significant T cell activation, demonstrated both by 3H-thymidine incorporation and by lysis of the TE671 cells, was found in the presence of added alpha 144-156 and, more importantly, in the absence of exogenous antigen. These results show that MHC class II-expressing muscle or other AChR-expressing cells could present endogenous AChR to pathogenic T cells. This process may be important in the aetiology of MG.

In order to study the immunogenetics of myasthenia gravis (MG), we analysed the TCR and HLA-class II genes from Italian and Californian myasthenic patients. We investigated polymorphisms of the TCR using the full length cDNA probes pGA5 and the pT10 for the alpha and beta chains, respectively. The 6.3 kb and 2.0 kb polymorphic markers, revealed by the PssI enzyme and the alpha chain probe, were shown to be significantly associated with MG. Italian MG patients were HLA typed, and allele frequencies showed a significant association of DR3 and DQw2 with MG. The relative risk calculated for DR3 was 7.4. T-cell proliferative responses to peptides of the AchR alpha chain were also studied and no associations with TCR RFLP analysis or HLA-class II typing were observed.

Histopathological studies confirm the prominent deposition of immunoglobulins (Ig) and the complement activation in acute demyelinating lesions of multiple sclerosis (MS) patients, suggesting that, at least in a subgroup of MS patients, autoantibodies could contribute to the disease. Recently, the ATP-sensitive inward rectifying potassium channel KIR4.1 has been identified as an antibody target in a small cohort of MS patients, since anti-KIR4.1 antibodies (Abs) were found in the serum of MS patients compared to those with other neurological disorders and healthy donors. Indeed, enhanced KIR4.1 expression was reported either in the brains of cuprizone-induced demyelination mouse model and in reactive astrocytes present at the borders of active MS lesions, suggesting that an abnormal KIR4.1 expression in inflamedMS brainsmight facilitate autoimmune sensitization against this channel. In the current study, we further investigated KIR4.1 expression in association with astrogliosis (GFAP), oligodendrocyte loss (MBP, CNPase) and neurodegeneration (beta-tubulin) in the cuprizone demyelinating model. C57BL/6 male mice were fed with cuprizone (0.2% w/w) for 5 weeks to induce acute demyelination. As control, agematched mice received normal chow diet. We observed a strong localization of KIR4.1 on GFAP-positive astrocytes in the cortex of mouse brain sections. Furthermore, serial brain sections from cuprizone-fed and control mice were immunostained with an MS serum resulted positive for anti-KIR4.1 Ab by ELISA assay using synthetic KIR4.1 peptides; confocal microscopy analysis showed a comparable immunolabelling pattern between MS serum and polyclonal KIR4.1 antibodies, suggesting that the KIR4.1-Abs in the MS serum indeed react with the native KIR4.1 antigen. KIR4.1 expression has also been investigated in experimental autoimmune encephalitis. Our data point further support the possible involvement of KIR4.1 as a candidate autoantigen in MS and are in line with recent reports. In this context, it might be relevant to address whether ‘danger’ signals alter KIR4.1 expression, as might occur in the inflammatory response to Theiler's virus-induced demyelination model.