Effect of IgG immunoadsorption on serum cytokines in MG and LEMS patients.

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.

Pixantrone (BBR2778) reduces the severity of experimental autoimmune myasthenia gravis in Lewis rats.

Pixantrone (BBR2778) (PIX) and mitoxantrone share the same mechanism of action because both drugs act as DNA intercalants and inhibitors of topoisomerase II. PIX is an interesting candidate immunosuppressant for the treatment of autoimmune diseases because of its reduced cardiotoxicity compared with mitoxantrone. The clinical response to conventional immunosuppressive treatments is poor in some patients affected by myasthenia gravis (MG), and new but well-tolerated drugs are needed for treatment-resistant MG. PIX was tested in vitro on rat T cell lines specific for the immunodominant peptide 97-116 derived from rat acetylcholine receptor (AChR), and showed strong antiproliferative activity in the nanomolar range. We demonstrate in this study that PIX administration reduced the severity of experimental autoimmune MG in Lewis rats. Biological and immunological analysis confirmed the effect of PIX, compared with vehicle-treated as well as mitoxantrone-treated experimental autoimmune MG rats. Anti-rat AChR Abs were significantly reduced in PIX-treated rats, and AChR content in muscles were found increased. Torpedo AChR-induced T cell proliferation tests were found reduced in both in vitro and ex vivo experiments. The effectiveness and the reduced cardiotoxicity make PIX a promising immunosuppressant agent suitable for clinical investigation in MG, although additional experiments are needed to confirm its safety profile in prolonged treatments.

Allorecognition of human neural stem cells by peripheral blood lymphocytes despite low expression of MHC molecules: role of TGF-beta in modulating proliferation.

Neural stem cells (NSCs) transplantation has been proposed as a means of restoring damaged brain tissue, a possibility rendered more likely by reports of low NSCs immunogenicity in various experimental models because of low expression of MHC class I and II as well as co-stimulatory molecules. We investigated the immunogenicity of a human NSC line grown in normal culture conditions and in the presence of pro-inflammatory cytokines IFN-gamma and tumor necrosis factor alpha by one-way mixed lymphocyte reaction (MLR) experiments with peripheral blood lymphocytes from eight HLA-incompatible donors. NSCs stimulated lymphocyte proliferation in almost all donors tested, with stimulation indices in the range of the low-end distribution curve of MLR between donors. The healthy subject that gave negative MLR results was the best compatible donor with respect to NSC haplotype. Since we observed low MLR responses overall, we studied if NSCs might exert any immunomodulatory activity. We detected transcription and release of the immunomodulatory molecule transforming growth factor beta (TGF-beta)-1; moreover, the addition of TGF-beta1 in MLR experiments down-regulated proliferative responses. To further confirm the immunological potential of human NSCs, we studied xenogeneic recognition of NSCs by immunocompetent cells derived from C57BL/6 mice, showing that NSCs can elicit an allo(xeno) response ex vivo. Our data indicate that NSCs have low but not negligible immunogenic potential that is sufficient to activate peripheral lymphocytes. Secretion of TGF-beta1 might balance the immunogenicity of NSCs. Nevertheless, the possibility that allo-NSCs grafting might induce in the long term an immune activation, thus vanishing their therapeutical effect, should not be overlooked and deserves further investigation.

Delayed administration of erythropoietin and its non-erythropoietic derivatives ameliorates chronic murine autoimmune encephalomyelitis.

Erythropoietin (EPO) mediates a wide range of neuroprotective activities, including amelioration of disease and neuroinflammation in rat models of EAE. However, optimum dosing parameters are currently unknown. In the present study, we used a chronic EAE model induced in mice by immunization with the myelin oligodendrocyte glycoprotein peptide (MOG35-55) to compare the effect of EPO given with different treatment schedules. EPO was administered intraperitoneally at 0.5, 5.0 or 50 microg/kg three times weekly starting from day 3 after immunization (preventive schedule), at the onset of clinical disease (therapeutic schedule) or 15 days after the onset of symptoms (late therapeutic schedule). The results show that EPO is effective even when given after the appearance of clinical signs of EAE, but with a reduced efficacy compared to the preventative schedule. To determine whether this effect requires the homodimeric EPO receptor (EPOR2)-mediated hematopoietic effect of EPO, we studied the effect of carbamylated EPO (CEPO) that does not bind EPOR2. CEPO, ameliorated EAE without changing the hemoglobin concentration. Another non-erythropoietic derivative, asialoEPO was also effective. Both EPO and CEPO equivalently decreased the EAE-associated production of TNF-alpha, IL-1beta and IL-1Ra in the spinal cord, and IFN-gamma by peripheral lymphocytes, indicating that their action involves targeting neuroinflammation. The lowest dosage tested appeared fully effective. The possibility to dissociate the anti-neuroinflammatory action of EPO from its hematopoietic action, which may cause undesired side effects in non-anemic patients, present new avenues to the therapy of multiple sclerosis.

Breakdown of tolerance to a self-peptide of acetylcholine receptor alpha-subunit induces experimental myasthenia gravis in rats.

Experimental autoimmune myasthenia gravis (EAMG), a model for human myasthenia (MG), is routinely induced in susceptible rat strains by a single immunization with Torpedo acetylcholine receptor (TAChR). TAChR immunization induces anti-AChR Abs that cross-react with self AChR, activate the complement cascade, and promote degradation of the postsynaptic membrane of the neuromuscular junction. In parallel, TAChR-specific T cells are induced, and their specific immunodominant epitope has been mapped to the sequence 97-116 of the AChR alpha subunit. A proliferative T cell response against the corresponding rat sequence (R97-116) was also found in TAChR-immunized rats. To test whether the rat (self) sequence can be pathogenic, we immunized Lewis rats with R97-116 or T97-116 peptides and evaluated clinical, neurophysiological, and immunological parameters. Clinical signs of the disease were noted only in R97-116-immunized animals and were confirmed by electrophysiological signs of impaired neuromuscular transmission. All animals produced Abs against the immunizing peptide, but anti-rat AChR Abs were observed only in animals immunized with the rat peptide. These findings suggested that EAMG in rats can be induced by a single peptide of the self AChR, that this sequence is recognized by T cells and Abs, and that breakdown of tolerance to a self epitope might be an initiating event in the pathogenesis of rat EAMG and MG.