Dendritic cells (DC) are highly specialized antigen-presenting cells characterized by the ability to prime T-cell responses. Mesenchymal stem cells (MSC) are adult stromal progenitor cells displaying immunomodulatory activities including inhibition of DC maturation in vitro. However, the specific impact of MSC on DC functions, upon in vivo administration, has never been elucidated. Here we show that murine MSC impair Toll-like receptor-4 induced activation of DC resulting in the inhibition of cytokines secretion, down-regulation of molecules involved in the migration to the lymph nodes, antigen presentation to CD4 + T cells, and cross-presentation to CD8 + T cells. These effects are associated with the inhibition of phosphorylation of intracellular mitogen-activated protein kinases. Intravenous administration of MSC decreased the number of CCR7 and CD49dβ1 expressing CFSE-labeled DC in the draining lymph nodes and hindered local antigen priming of DO11.10 ovalbumin-specific CD4 + T cells. Upon labeling of DC with technetium-99m hexamethylpropylene amine oxime to follow their in vivo biodistribution, we demonstrated that intravenous injection of MSC blocks, almost instantaneously, the migration of subcutaneously administered ovalbumin-pulsed DC to the draining lymph nodes. These findings indicate that MSC significantly affect DC ability to prime T cells in vivo because of their inability to home to the draining lymph nodes and further confirm MSC potentiality as therapy for immune-mediated diseases.immunomodulation | tolerance S tromal progenitors of mesodermal cells, referred to as mesenchymal stem cells (MSC) or multipotent mesenchymal stromal cells, are a heterogeneous population of self-renewing and multipotent cells isolated from the bone marrow (BM) (1). MSC raised hopes for their clinical exploitation for tissue-repair strategies and increasing experimental evidence supports their use also for immune-mediated diseases (2). In fact, MSC display a striking capacity of modulating the immune response (3). Despite a large body of experimental studies addressing the in vitro effects of MSC on immune cells, little is known about the mechanisms of MSCmediated inhibition of the in vivo immune response. Dendritic cells (DC) are unique antigen-presenting cells (APCs) endowed with the ability of acquiring and processing antigens, up-regulating costimulatory molecules and therefore priming naive T cells. To present antigens to naive T cells, CCR7-expressing DC must migrate through lymphatic vessels from sites of inflammation to the closest draining lymph node (4). Activation of DC via Toll-like receptors (TLRs) up-regulates the expression of chemokine receptors involved in DC migration to the lymph nodes and enhances their in vivo mobilization properties (5). As a consequence, the total number of DC migrating in the draining lymph nodes deeply affects naive T-cell priming (6). Here we show that murine MSC inhibit in vitro DC effector properties, including antigen processing and presentation to T cells through the inhib...

Adenosine deaminase 2 deficiency (DADA2) is an autoinflammatory disease characterized by inflammatory vasculopathy, early strokes associated often with hypogammaglobulinemia. Pure red cell aplasia, thrombocytopenia, and neutropenia have been reported. The defect is due to biallelic loss of function of ADA2 gene, coding for a protein known to regulate the catabolism of extracellular adenosine. We therefore investigated immune phenotype and B‐ and T‐cell responses in 14 DADA2 patients to address if ADA2 mutation affects B‐ and T‐cell function. Here, we show a significant decrease in memory B cells, in particular class switch memory, and an expansion of CD21low B cells in DADA2 patients. In vitro stimulated B lymphocytes were able to secrete nonfunctional ADA2 protein, suggesting a cell intrinsic defect resulting in an impairment of B‐cell proliferation and differentiation. Moreover, CD4+ and CD8+ T cells were diminished; however, the frequency of circulating T follicular helper cells was significantly increased but they had an impairment in IL‐21 production possibly contributing to an impaired B cell help. Our findings suggest that ADA2 mutation could lead to a B‐cell intrinsic defect but also to a defective Tfh cell function, which could contribute to the immunodeficient phenotype reported in DADA2 patients.

Autosomal recessive osteopetrosis (ARO) is a severe bone disease characterized by increased bone density due to impairment in osteoclast resorptive function or differentiation. Hematopoietic stem cell transplantation is the only available treatment; however, this therapy is not effective in RANKL-dependent ARO, since in bone this gene is mainly expressed by cells of mesenchymal origin. Of note, whether lack of RANKL production might cause a defect also in the bone marrow (BM) stromal compartment, possibly contributing to the pathology, is unknown. To verify this possibility, we generated and characterized BM mesenchymal stromal cell (BM-MSC) lines from wild type and Rankl mice, and found that Rankl BM-MSCs displayed reduced clonogenicity and osteogenic capacity. The differentiation defect was significantly improved by lentiviral transduction of Rankl BM-MSCs with a vector stably expressing human soluble RANKL (hsRANKL). Expression of Rankl receptor, Rank, on the cytoplasmic membrane of BM-MSCs pointed to the existence of an autocrine loop possibly activated by the secreted cytokine. Based on the close resemblance of RANKL-defective osteopetrosis in humans and mice, we expect that our results are also relevant for RANKL-dependent ARO patients. Data obtained in vitro after transduction with a lentiviral vector expressing hsRANKL would suggest that restoration of RANKL production might not only rescue the defective osteoclastogenesis of this ARO form, but also improve a less obvious defect in the osteoblast lineage, thus possibly achieving higher benefit for the patients, when the approach is translated to clinics. Stem Cells 2017;35:1365-1377.

The capability of discontinuous finite element methods of handling non-matching grids is exploited in the simulation of rotating electrical machines. During time stepping, the relative movement of two meshes, consistent with two different regions of the electrical device (rotor and stator), results in the generation of so-called hanging nodes on the slip surface. A discretisation of the problem in the air-gap region between rotor and stator, which relies entirely on finite element methods, is presented here. A discontinuous Galerkin method is applied in a small region containing the slip surface, and a conforming method is used in the remaining part

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