Several autoimmune diseases are mediated by antibodies produced after deregulations of the immune system and directed against self antigens. Myasthenia Gravis (MG) is a rare disease in which pathogenicity is due to autoantibodies directed against the neuromuscular endplate. MG is not really cured, corticosteroids and azathioprin are commonly used, however they trigger severe side-effects, mandating the setup of novel therapies. Mesenchymal Stromal/Stem Cells (MSC) are multipotent progenitor cells that can be isolated from various human tissues and can modulate the immune system via soluble mediators and cell-cell contacts. Our team has recently validated a new animal model of MG, in which we demonstrated that the transfer of MSC conditioned by peripheral blood mononucleated cells (PBMC) improved the clinical status of the animals (Sudres et al., JCI Insight 2017). To develop this immunomodulating approach in clinical perspective, we compared the phenotypes of research-grade (RG) and clinical-grade (CG) MSC testing a series of 60 antibodies (Ab) directed against surface antigens by flow cytometry. We evaluated the variations introduced by different conditioning treatments (activation by gamma-interferon, cross-stimulation by PBMC or monocytes). Markers involved in immunomodulation (recognition, activation, function of complement, co-stimulation, immune checkpoints) were increased or decreased depending on treatment. Adhesion molecules and receptors were also differentially modified (integrins, selectins, cell-cell adhesion molecules, growth factor receptors, tetraspanins). These results suggest that the conditioning regimens act through different pathways. From this panel, we derived a second one of 31 Ab allowing simultaneous labeling of MSC at single cell level by mass cytometry (CyTOF). We defined MSC clusters which were modulated upon activation. In parallel, we evaluated the functional activity of resting or conditioned CG MSC through a cell proliferation assay, and through the quantification by ELISA of secreted immunomodulating products. The conditioning regimens differentially modulated the secretion of Prostaglandin E2 and TGFbeta1, and inhibited PBMC proliferation. This work unveiled phenotypic and functional markers of MSC along with their modulations according to different treatments, and will contribute to validate a cell therapy product for immunomodulation purposes.

A chronic autoimmune disease, myasthenia gravis (MG) is characterized in 85% of patients by antibodies directed against the acetylcholine receptor (AChR) located at the neuromuscular junction. The functional and effective balance between regulatory T cells (T reg cells) and effector T cells (T eff cells) is lost in the hyperplastic thymus of MG patients with antibodies specific for the AChR (AChR + MG patients). The objective of this review is to describe how T reg cells and inflammatory T cells participate in this imbalance and contribute to induce a chronic inflammatory state in the MG thymus. We discuss the origins and characteristics of T reg cells and their reported dysfunctions in AChR + MG patients. We also review the inflammatory condition observed in MG thymus, including overexpression of interleukin (IL)-1β, IL-6, and IL-23, cytokines that promote the differentiation of T helper 17 (T H 17) cells and the expression of IL-17. We summarize the preclinical models used to determine the implication of expression of cytokines, such as IL-6, IL-12 (IL-23 subunit), IL-17, and interferon γ to the development of experimental autoimmune MG. Finally, we suggest that biological agents, such as humanized monoclonal antibodies that target the IL-23/T H 17 pathway, should be investigated in the context of MG, as they have proven efficiency in other autoimmune diseases.

A chronic autoimmune disease, myasthenia gravis (MG) is characterized in 85% of patients by antibodies directed against the acetylcholine receptor (AChR) located at the neuromuscular junction. The functional and effective balance between regulatory T cells (Treg cells) and effector T cells (Teff cells) is lost in the hyperplastic thymus of MG patients with antibodies specific for the AChR (AChR+ MG patients). The objective of this review is to describe how Treg cells and inflammatory T cells participate in this imbalance and contribute to induce a chronic inflammatory state in the MG thymus. We discuss the origins and characteristics of Treg cells and their reported dysfunctions in AChR+ MG patients. We also review the inflammatory condition observed in MG thymus, including overexpression of interleukin (IL)‐1β, IL‐6, and IL‐23, cytokines that promote the differentiation of T helper 17 (TH17) cells and the expression of IL‐17. We summarize the preclinical models used to determine the implication of expression of cytokines, such as IL‐6, IL‐12 (IL‐23 subunit), IL‐17, and interferon γ to the development of experimental autoimmune MG. Finally, we suggest that biological agents, such as humanized monoclonal antibodies that target the IL‐23/TH17 pathway, should be investigated in the context of MG, as they have proven efficiency in other autoimmune diseases.

A chronic autoimmune disease, myasthenia gravis (MG) is characterized in 85% of patients by antibodies directed against the acetylcholine receptor (AChR) located at the neuromuscular junction. The functional and effective balance between regulatory T cells (T-reg cells) and effector T cells (T-eff cells) is lost in the hyperplastic thymus of MG patients with antibodies specific for the AChR (AChR(+) MG patients). The objective of this review is to describe how T-reg cells and inflammatory T cells participate in this imbalance and contribute to induce a chronic inflammatory state in the MG thymus. We discuss the origins and characteristics of T-reg cells and their reported dysfunctions in AChR(+) MG patients. We also review the inflammatory condition observed in MG thymus, including overexpression of interleukin (IL)-1, IL-6, and IL-23, cytokines that promote the differentiation of T helper 17 (T(H)17) cells and the expression of IL-17. We summarize the preclinical models used to determine the implication of expression of cytokines, such as IL-6, IL-12 (IL-23 subunit), IL-17, and interferon to the development of experimental autoimmune MG. Finally, we suggest that biological agents, such as humanized monoclonal antibodies that target the IL-23/T(H)17 pathway, should be investigated in the context of MG, as they have proven efficiency in other autoimmune diseases.