Allogeneic Responses Research Articles

Stem Cells and Regenerative Medicine: Myth or Reality of the 21th Century.

Since the 1960s and the therapeutic use of hematopoietic stem cells of bone marrow origin, there has been an increasing interest in the study of undifferentiated progenitors that have the ability to proliferate and differentiate into various tissues. Stem cells (SC) with different potency can be isolated and characterised. Despite the promise of embryonic stem cells, in many cases, adult or even fetal stem cells provide a more interesting approach for clinical applications. It is undeniable that mesenchymal stem cells (MSC) from bone marrow, adipose tissue, or Wharton's Jelly are of potential interest for clinical applications in regenerative medicine because they are easily available without ethical problems for their uses. During the last 10 years, these multipotent cells have generated considerable interest and have particularly been shown to escape to allogeneic immune response and be capable of immunomodulatory activity. These properties may be of a great interest for regenerative medicine. Different clinical applications are under study (cardiac insufficiency, atherosclerosis, stroke, bone and cartilage deterioration, diabetes, urology, liver, ophthalmology, and organ's reconstruction). This review focuses mainly on tissue and organ regeneration using SC and in particular MSC.

Allogeneic inducible regulatory T cells generated with retinoic acid allow the generation of mixed chimerism via nonmyeloablative conditioning in mice models

Allogeneic inducible regulatory T cells generated with retinoic acid allow the generation of mixed chimerism via nonmyeloablative conditioning in mice models

DIAZEPAM EFFECTS ON IMMUNE CELLS ACTIVELY INVOLVED DURING THE DEVELOPMENT OF EXPERIMENTAL AUTOIMMUNE ENCEPHALOMYELITIS.

DIAZEPAM EFFECTS ON IMMUNE CELLS ACTIVELY INVOLVED DURING THE DEVELOPMENT OF EXPERIMENTAL AUTOIMMUNE ENCEPHALOMYELITIS.

Therapeutic blockade of LIGHT interaction with herpesvirus entry mediator and lymphotoxin β receptor attenuates in vivo cytotoxic allogeneic responses.

Tumor necrosis factor/tumor necrosis factor receptor superfamily members conform a group of molecular interaction pathways of essential relevance during the process of T-cell activation and differentiation toward effector cells and particularly for the maintenance phase of the immune response. Specific blockade of these interacting pathways, such as CD40-CD40L, contributes to modulate the deleterious outcome of allogeneic immune responses. We postulated that antagonizing the interaction of LIGHT expression on activated T cells with its receptors, herpesvirus entry mediator and lymphotoxin β receptor, may decrease T cell-mediated allogeneic responses. A flow cytometry competition assay was designed to identify anti-LIGHT monoclonal antibodies capable to prevent the interaction of mouse LIGHT with its receptors expressed on transfected cells. An antibody with the desired specificity was evaluated in a short-term in vivo allogeneic cytotoxic assay and tested for its ability to detect endogenous mouse LIGHT. We provide evidence for the first time that in mice, as previously described in humans, LIGHT protein is rapidly and transiently expressed after T-cell activation, and this expression was stronger on CD8 T cells than on CD4 T cells. Two anti-LIGHT antibodies prevented interactions of mouse LIGHT with its two known receptors, herpesvirus entry mediator and lymphotoxin β receptor. In vivo administration of anti-LIGHT antibody (clone 10F12) ameliorated host antidonor short-term cytotoxic response in wild type B6 mice, although to a lesser extent than that observed in LIGHT-deficient mice. The therapeutic targeting of LIGHT may contribute to achieve a better control of cytotoxic responses refractory to current immunosuppressive drugs in transplantation.

Fasciola hepatica Kunitz type molecule decreases dendritic cell activation and their ability to induce inflammatory responses.

The complete repertoire of proteins with immunomodulatory activity in Fasciola hepatica (Fh) has not yet been fully described. Here, we demonstrated that Fh total extract (TE) reduced LPS-induced DC maturation, and the DC ability to induce allogeneic responses. After TE fractionating, a fraction lower than 10 kDa (F<10 kDa) was able to maintain the TE properties to modulate the DC pro- and anti-inflammatory cytokine production induced by LPS. In addition, TE or F<10 kDa treatment decreased the ability of immature DC to stimulate the allogeneic responses and induced a novo allogeneic CD4+CD25+Foxp3+ T cells. In contrast, treatment of DC with T/L or F<10 kDa plus LPS (F<10/L) induced a regulatory IL-27 dependent mechanism that diminished the proliferative and Th1 and Th17 allogeneic responses. Finally, we showed that a Kunitz type molecule (Fh-KTM), present in F<10 kDa, was responsible for suppressing pro-inflammatory cytokine production in LPS-activated DC, by printing tolerogenic features on DC that impaired their ability to induce inflammatory responses. These results suggest a modulatory role for this protein, which may be involved in the immune evasion mechanisms of the parasite.

Therapeutic Effects of MLN4924 on Sclerodermatous Chronic Graft Versus Host Disease

▪Allogeneic hematopoietic stem cell transplantation (HSCT) remains the only curative option for the treatment of a variety of hematological diseases. However, high incidences of graft versus host disease (GVHD) and tumor relapse remain as major hurdles to this approach. While recent advances in transplant preparation and prophylactic regimens have lowered the incidence of acute GVHD, chronic GVHD (cGVHD) still remains a major cause of long-term morbidity and mortality. Recent studies have suggested that post-translation modifications (PTMs) may serve as therapeutic targets during GVHD. PTMs of proteins are important pathways that confer biochemical alterations, such as acetylation, phosphorylation, and ubiquitination. Targeting PTMs by using small molecular inhibitors has demonstrated potent anti-tumor effects, as well as immune modulatory properties. We have previously shown that bortezomib, an inhibitor of PTMs pathways, can successfully ameliorate sclerodermatous cGVHD responses in both preclinical and clinical studies. Here we reported a new small molecular targeting agent, MLN4924, a selective inhibitor of NEDD8-activating enzyme, on the treatment of cGVHD.MLN4924 is a selective inhibitor of NEDD8-activating enzyme and has been shown to be well tolerated at higher doses and exhibit potent anti-tumor activity in murine models and in early clinical trials. Furthermore, MLN4924 can suppress dendritic cell functions, as well as their production of proinflammatory cytokines during allogeneic responses. Due to these findings, we sought to test the treatment effects of MLN4924 on cGVHD responses. To investigate this, we utilized a minor MHC mismatch murine model by transferring donor B10.D2 (H-2d) cells into BALB/c (H-2d) recipients. MLN4924 or vehicle control (10% 2-hydroxy-propyl-beta cyclodextrin) was injected intraperitoneally on day 20, the point at which skin sclerodermatous cGVHD is initiated. Compared with the vehicle groups, animals that received either bortezomib (0.1 mg/kg) or MLN4924 (20 mg/kg) developed significantly less cGVHD, as determined by clinical scores (2.34±0.34 versus 1.03±0.37 versus 0.8±0.14, respectively; P <0.01). Surprisingly, a preventive approach started from either day 0 or day 10 post-HSCT resulted in higher cGVHD scores compared to early therapeutic interventions, started from Day 20, (3.3 and 2.37± 0.18 versus 0.8±0.14, respectively). The temporally dependent efficacy of MLN4924 suggests that PTMs may play a suppressive role in the early development of cGVHD pathogenesis while worsening cGVHD response as a prevention treatment. Flow cytometric analysis revealed a significant reduction in the total number of macrophages and dendritic cells with MLN4924 treatment starting on day 20, while no significant changes were noticed in T cell subpopulations. Similarly, MLN4924 can successfully inhibit mixed lymphocyte reactions (MLR) in vitro. Importantly, a reduction in the total number of plasma cells, a major source of autoantibody production, was also observed. Together these data suggest that inhibition of neddylation with small molecules, such as MLN4924, can be used as a new approach for the treatment of patients with sclerodermatous cGVHD, while potentially maintaining graft versus tumor effects through preserving T cell populations. DisclosuresNo relevant conflicts of interest to declare.

Interleukin-7 Represses the Immunoregulatory Function of Human TCRαβ+ CD4- CD8- Double-Negative (DN) T Cells By Activating Akt/mTOR Signaling

Regulatory T (Treg) cells have been shown to be involved in downregulating immune responses in autoimmunity, transplant rejection, and graft-versus-host disease (GvHD). Recently, a novel subset of TCRαβ+ CD4- CD8- (double negative, DN) T cells has been described to possess a very potent suppressive activity on allogeneic T-cell responses in both mice and humans. Of interest, clinical studies in patients after allogeneic stem cell transplantation (SCT) revealed an inverse correlation between the frequency of circulating DN T cells and the severity of GvHD. Interleukin (IL)-7 is required for survival and homeostasis of mature T-cells and has been shown to modulate the functional activity of Treg cells. Here we asked whether IL-7 affects the suppressive activity of human DN T cells. We found that human DN T cells isolated from peripheral blood lymphocytes do express the IL-7 receptor and are able to transduce IL-7 downstream signaling. Intriguingly, IL-7 significantly diminished the suppressive activity of DN T cells towards allogeneic CD4+ and CD8+ T cells. Thereby, IL-7 did not render the responder T cells insensitive to suppression. Instead, blocking of key signaling molecules revealed that IL-7 has a direct impact on the suppressive activity of DN T cells. Further analyses demonstrated that IL-7 activates Akt/mTOR signaling in DN T cells. Importantly, selective inhibition of the Akt or mTOR protein kinase was able to reverse the IL-7 effect thereby restoring the suppressive function of DN T cells, whereas inhibition of other central T-cell signaling pathways did not. Thus, DN T-cell mediated suppression is impaired by IL-7 due to crucial activation of the Akt/mTOR signaling cascade. These findings indicate that IL-7 and Akt/mTOR signaling are critical factors for the suppressive capacity of DN T cells. Targeting of these pathways by pharmacological agents may restore and/or enhance DN T-cell functionality in GvHD. DisclosuresNo relevant conflicts of interest to declare.

Relationship between Gene Polymorphism of Recipient/ Donor Immune Pathway and Invasive Fungal Infection after Allogeneic Hematopoietic Stem Cell Transplantation

▪Invasive fungal infections are a major cause of morbidity and mortality after allogeneic hematopoietic stem cell transplantation(allo-HSCT). During the past 2 decades, changes in transplantation practices and strategies to diagnose and treat IFI have likely impacted the epidemiology of IFI. Polymorphism of genes, which take part in the allogeneic immune response after allo-HSCT, lead to allograft immunoreactivity differences between individuals. It also may affect IFI after transplantation.Methods: We analyzed allo-HSCT recipients at our center during the period January 2001 through March 2009. We analysis gene polymorphism of innate immune gene TLRs among 240 pairs of specimens of recipients and donors, in order to find out IFI individual difference and high risk genotype of IFI after transplantation.Results: There were 99 patients (41.2%) occured IFI after allo-HSCT. Hematological malignant diseases, serious acute GVHD, and extensive chronic GVHD were risk factor for IFI after allo-HSCT. Univariate analysis of the relationship between risk factors of IFI after all0-HSCT and the TLRs gene polymorphism, we found that in the 10 SNP loci in 5 TLRs , two polymorphisms of TLR8 gene, (+1 A/G, rs3764880; +354 C/T, rs2159377) effect the incidence of IFI after allo-HSCT. Other gene polymorphism of TLRs (TLR1, TLR2, TLR3, TLR9) had no significant effects on the risk of IFI after allo-HSCT.Conclusion: The study of the relationship between the gene polymorphism of natural immune molecule TLRs and the risk factors after allo-HSCT showed that TLR8 genotype of donor stem cell significantly influenced the incidence of IFI after allo-HSCT at the first time. It provide the evidence to establishment a fungal infection index system, which based on risk stratification of genetic background before transplantation of donors and recipients stem cell, and provide basis for selection of unrelated donor and prevention and treatment of IFI DisclosuresNo relevant conflicts of interest to declare.

NLRP10-Deficient Mice Reveal a Crucial Role for Dendritic Cell Activity in the Initiation of the Allogeneic Response to Transfused Red Blood Cells

The generation of antibodies against transfused red blood cells (RBCs) can pose a serious health risk, especially in chronically transfused patients requiring life-long transfusion support; yet our understanding of what immune signals or cells dictate when someone will become alloimmunized is lacking. Every non-autologous red cell unit has multiple antigens foreign to the transfused recipient; some people respond to these foreign antigens with an adaptive immune response and some do not. Given the now well established role of innate immune signals in regulating adaptive immunity, understanding if and how innate immunity is triggered during transfusion may allow development of therapies to prevent alloimmunization in chronically transfused subjects such as those with myelodysplasia or hemoglobinopathies. We have established a murine model system in which we can evaluate both the role of particular innate immune stimuli as well as particular cells of the immune system in regulating the allogeneic response to transfused red blood cells. A particularly useful transgenic “HOD mouse” has been engineered, which encodes a triple fusion protein and provides a unique tool to directly assess both RBC-specific T and B cell responses. This RBC-specific antigen contains the model protein antigen hen egg lysozyme (HEL) fused to chicken ovalbumin (OVA) fused to the human Duffybblood group antigen (HEL-OVA-Duffy) as an integral membrane protein under control of the beta globin promoter. Transfusion of genetically targeted mice lacking various innate immune receptors allows us to screen for important immune pathways regulating the response to allogeneic RBCs.Using these models, we recently discovered that mice lacking the NOD-like receptor NLRP10 fail to develop alloimmunity to transfused red blood cells. Surprisingly, the early innate immune cytokine response, including IL-6, IL-1beta and TNF-alpha, was unaffected in mice lacking NLRP10. Yet both B cell and T cell activation in the spleen to the transgenic transfused RBCs was abrogated. Inclusion of OVA in the alloantigen of the HOD mice allows us to readily study naïve CD4+ T cell activation following transfusion by using the OTII T cell receptor (TCR) transgenic mice in which essentially all T cells express one antigen receptor specific for a peptide of OVA. By tracking rounds of cell division we found that adoptively transferred OTII undergo more than 5-8 rounds of division in the spleen three days following transfusion of HOD RBCs in WT recipients. In contrast, no OTII proliferation was observed in NLRP10-deficient mice following OTII adoptive transfer and HOD RBC transfusion, suggesting that T cells are failing to receive activation signals by splenic antigen presenting cells. We have previously demonstrated that NLRP10-deficient dendritic cells fail to migrate from peripheral tissues such as the skin to draining lymph nodes. Our preliminary data now suggest that NLRP10-deficient dendritic cells are able to process and present RBC-derived antigens, but do not migrate to T cell zones in the spleen to prime naïve RBC-specific T cells. The relative role of dendritic cells, B cells and macrophages in the induction of erythrocyte alloimmunization remain unclear. Further, the need for DC migration within the spleen in the induction of alloimmunity to transfused RBCs has not been addressed. These mice allow us for the first time to answer these fundamental immunologic questions during transfusion. Future work will aim to determine how dendritic cell movement within the spleen is regulated during transfusion in NLRP10-deficient mice and the specific role of splenic dendritic cells in CD4+ T cell priming to allogeneic RBCs. DisclosuresNo relevant conflicts of interest to declare.

Vitrification of heart valve tissues.

Application of the original vitrification protocol used for pieces of heart valves to intact heart valves has evolved over time. Ice-free cryopreservation by Protocol 1 using VS55 is limited to small samples where relatively rapid cooling and warming rates are possible. VS55 cryopreservation typically provides extracellular matrix preservation with approximately 80 % cell viability and tissue function compared with fresh untreated tissues. In contrast, ice-free cryopreservation using VS83, Protocols 2 and 3, has several advantages over conventional cryopreservation methods and VS55 preservation, including long-term preservation capability at -80 °C; better matrix preservation than freezing with retention of material properties; very low cell viability, reducing the risks of an immune reaction in vivo; reduced risks of microbial contamination associated with use of liquid nitrogen; improved in vivo functions; no significant recipient allogeneic immune response; simplified manufacturing process; increased operator safety because liquid nitrogen is not used; and reduced manufacturing costs.

The progression of cell death affects the rejection of allogeneic tumors in immune-competent mice - implications for cancer therapy.

Large amounts of dead and dying cells are produced during cancer therapy and allograft rejection. Depending on the death pathway and stimuli involved, dying cells exhibit diverse features, resulting in defined physiological consequences for the host. It is not fully understood how dying and dead cells modulate the immune response of the host. To address this problem, different death stimuli were studied in B16F10 melanoma cells by regulated inducible transgene expression of the pro-apoptotic active forms of caspase-3 (revCasp-3), Bid (tBid), and the Mycobacterium tuberculosis-necrosis inducing toxin (CpnTCTD). The immune outcome elicited for each death stimulus was assessed by evaluating the allograft rejection of melanoma tumors implanted subcutaneously in BALB/c mice immunized with dying cells. Expression of all proteins efficiently killed cells in vitro (>90%) and displayed distinctive morphological and physiological features as assessed by multiparametric flow cytometry analysis. BALB/c mice immunized with allogeneic dying melanoma cells expressing revCasp-3 or CpnTCTD showed strong rejection of the allogeneic challenge. In contrast, mice immunized with cells dying either after expression of tBid or irradiation with UVB did not, suggesting an immunologically silent cell death. Surprisingly, immunogenic cell death induced by expression of revCasp-3 or CpnTCTD correlated with elevated intracellular reactive oxygen species (ROS) levels at the time point of immunization. Conversely, early mitochondrial dysfunction induced by tBid expression or UVB irradiation accounted for the absence of intracellular ROS accumulation at the time point of immunization. Although ROS inhibition in vitro was not sufficient to abrogate the immunogenicity in our allo-immunization model, we suggest that the point of ROS generation and its intracellular accumulation may be an important factor for its role as damage associated molecular pattern in the development of allogeneic responses.

Increased bone marrow (BM) plasma level of soluble CD30 and correlations with BM plasma level of interferon (IFN)-γ, CD4/CD8 T-cell ratio and disease severity in aplastic anemia.

Idiopathic aplastic anemia (AA) is an immune-mediated bone marrow failure syndrome. Immune abnormalities such as decreased lymphocyte counts, inverted CD4/CD8 T-cell ratio and increased IFN-γ-producing T cells have been found in AA. CD30, a surface protein belonging to the tumor necrosis factor receptor family and releasing from cell surface as a soluble form (sCD30) after activation, marks a subset of activated T cells secreting IFN-γ when exposed to allogeneic antigens. Our study found elevated BM plasma levels of sCD30 in patients with SAA, which were closely correlated with disease severity, including absolute lymphocyte count (ALC) and absolute netrophil count (ANC). We also noted that sCD30 levels were positively correlated with plasma IFN-γ levels and CD4/CD8 T-cell ratio in patients with SAA. In order to explain these phenomena, we stimulated T cells with alloantigen in vitro and found that CD30+ T cells were the major source of IFN-γ, and induced CD30+ T cells from patients with SAA produced significantly more IFN-γ than that from healthy individuals. In addition, increased proportion of CD8+ T cells in AA showed enhanced allogeneic response by the fact that they expressed more CD30 during allogeneic stimulation. sCD30 levels decreased in patients responded to immunosuppressive therapy. In conclusion, elevated BM plasma levels of sCD30 reflected the enhanced CD30+ T cell-mediated immune response in SAA. CD30 as a molecular marker that transiently expresses on IFN-γ-producing T cells, may participate in mediating bone marrow failure in AA, which also can facilitate our understanding of AA pathogenesis to identify new therapeutic targets.

IL2-IL21 gene cluster polymorphism is not associated with allograft function after kidney transplantation.

Background Cytokines are key mediators of the immune response after transplantation. The interleukin (IL)-2 cytokine family, which includes IL-2, IL-4, IL-7, IL-9, IL-15, and IL-21, is of particular interest because of its importance in the allogenic response. The aim of this study was to examine the association between the rs6822844 gene polymorphism in the IL2-IL21 region and allograft function after kidney transplantation.MethodsThe study enrolled 270 Caucasian kidney allograft recipients (166 males and 104 females, mean age 47.63 ± 12.96 years). Following parameters were recorded in each case: recipient’s age, delayed graft function (DGF), occurrence and number of episodes of acute rejection (AR), and chronic allograft dysfunction (CAD). Genotyping of the rs6822844 IL2-IL21 cluster gene polymorphism was performed using real-time PCR assay.ResultsThere were no statistically significant differences in the genotypes and alleles of the rs6822844 IL2-IL21 cluster gene polymorphism among patients with DGF (p = 0.72), AR (p = 0.69) and CAD (p = 0.77), or in creatinine concentrations 1, 3, 6, 12, 24 or 36 months after transplantation (p = 0.46, p = 0.58, p = 0.6, p = 0.72, p = 0.7, p = 0.76, respectively).ConclusionIt seems that the rs6822844 IL2-IL21 gene cluster polymorphism is of little importance in allograft function after kidney transplantation.

Combining autologous dendritic cell therapy with CD3 antibodies promotes regulatory T cells and permanent islet allograft acceptance.

Cell therapy and the use of mAbs that interfere with T cell effector functions constitute promising approaches for the control of allograft rejection. In the current study, we investigated a novel approach combining administration of autologous tolerogenic dendritic cells with short-term treatment with CD3-specific Abs. Permanent acceptance of pancreatic islet allografts was achieved in mice treated with the combination therapy the day before transplantation but not in recipients treated with either therapy alone. The combination treatment induced a marked decrease in T cells infiltrating the allografts and a sustained reduction of antidonor responses. Importantly, CD4(+)Foxp3(+) regulatory T cells appeared to play a crucial role in the long-term graft acceptance. Their frequency increased significantly in the spleen, draining lymph nodes, and transplanted islets and remained elevated over the long term; they exhibited increased donor-specific suppressive functions; and their removal at the time of transplantation abrogated the therapeutic effect of the combined therapy. These results support the therapeutic potential of protocols combining autologous dendritic cells and low-dose CD3 Abs, both currently in clinical development, and that act in synergy to control allogeneic immune responses and favor graft survival in a full-mismatch situation.

Clinical implication of allogenic implantation of adipogenic differentiated adipose-derived stem cells.

We recently reported that autologous adipogenic differentiated adipose-derived stem cells (ASCs) can potentially be used as an effective and safe therapy for soft-tissue regeneration. In the present study, we investigated whether adipogenic differentiated ASCs can be used for allogenic applications to enlarge their therapeutic use. The allogenic immune response of adipogenic differentiated ASCs was investigated by flow cytometry and mixed lymphocyte culture. To determine whether adipogenic differentiated ASCs can form new adipose tissue without immune rejection, these cells were implanted subcutaneously into allo- or xenogenic recipient mice. In addition, the safety of the allogenic implantation of adipogenic differentiated ASCs was explored in a phase I clinical study. Adipogenic differentiated ASCs do not express major histocompatibility complex (MHC) class II molecules and costimulatory molecules, and the expression levels of MHC class I decreased after differentiation. In addition, these cells do not elicit an immune response against MHC-mismatched allogenic lymphocytes and formed new adipose tissue without immune rejection in the subcutaneous region of MHC-mismatched mice. Moreover, these cells did not induce clinically significant local and systemic immune responses or adverse events in the subcutaneous region of donor-independent healthy subjects. These results suggest that adipogenic differentiated ASCs can be used as a "universal donor" for soft-tissue engineering in MHC-mismatched recipients.

Changes in immunological profile of allogeneic mesenchymal stem cells after differentiation: should we be concerned?

Mesenchymal stem cells (MSCs) are an adult stromal cell population possessing potent differentiation capacity and a potential for use across major histocompatibility complex barriers. Although allogeneic MSCs have potent immunosuppressive properties, evidence also suggests that they elicit a weak allogeneic immune response. However, the effect of induced differentiation on the immunosuppressive ability and immunogenicity of allogeneic MSCs is a potential obstacle when applying MSCs in tissue replacement therapies. These concerns will be explored in this review, with particular emphasis on changes in the cell surface expression of immunogenic markers, changes in the secretion of immunosuppressive molecules and in vivo functional benefits of the cell therapy. We review the literature from a translational point of view, focusing on pre-clinical studies that have utilised and analysed the effects of allogeneic immune responses on the ability of allogeneic MSCs to regenerate damaged tissue in models of bone, heart and cartilage defects.

Orchestration of transplantation tolerance by regulatory dendritic cell therapy or in-situ targeting of dendritic cells.

Extensive research in murine transplant models over the past two decades has convincingly demonstrated the ability of regulatory dendritic cells (DCregs) to promote long-term allograft survival. We review important considerations regarding the source of therapeutic DCregs (donor or recipient) and their mode of action, in-situ targeting of DCregs, and optimal therapeutic regimens to promote DCreg function. Recent studies have defined protocols and mechanisms whereby ex-vivo-generated DCregs of donor or recipient origin subvert allogeneic T-cell responses and promote long-term organ transplant survival. Particular interest has focused on how donor antigen is acquired, processed and presented by autologous dendritic cells, on the stability of DCregs, and on in-situ targeting of dendritic cells to promote their tolerogenic function. New evidence of the therapeutic efficacy of DCregs in a clinically relevant nonhuman primate organ transplant model and production of clinical grade DCregs support early evaluation of DCreg therapy in human graft recipients. We discuss strategies currently used to promote dendritic cell tolerogenicity, including DCreg therapy and in-situ targeting of dendritic cells, with a view to improved understanding of underlying mechanisms and identification of the most promising strategies for therapeutic application.

Tolerogenic signaling by pulmonary CD1c+ dendritic cells induces regulatory T cells in patients with chronic obstructive pulmonary disease by IL-27/IL-10/inducible costimulator ligand

Increased mortality rates in patients with chronic obstructive pulmonary disease (COPD) are largely due to severe infectious exacerbations. Impaired respiratory immunity is linked to the enhanced susceptibility to infections. Dendritic cells (DCs) direct host immune responses toward immunity or tolerance. Pulmonary CD1c(+) DCs elicit robust antiviral immune responses in healthy subjects. Nevertheless, their functional specialization in patients with COPD remains unexplored. We sought to better understand the mechanisms that suppress respiratory immunity in patients with COPD by examining the immunostimulatory and tolerogenic properties of pulmonary CD1c(+) DCs. We analyzed the expression of costimulatory and tolerogenic molecules by pulmonary CD1c(+) DCs from patients with COPD (CD1c(+)DCCOPD) and former smokers without COPD. We isolated lung CD1c(+) DCs and determined their ability to stimulate allogeneic T-cell responses. The suppressive effects of lung CD1c(+) DCs and CD1c(+) DC-primed T cells on mixed leukocyte reactions were examined. An experimental human model of COPD exacerbation was used to investigate the levels of critical immunosuppressive molecules invivo. CD1c(+) DCs from patients with COPD hinder T-cell effector functions and favor the generation of suppressive IL-10-secreting CD4(+) T cells that function through IL-10 and TGF-β. IL-27, IL-10, and inducible T-cell costimulator ligand signaling are essential for CD1c(+)DCCOPD-mediated differentiation of IL-10-producing suppressive T cells. Exposure of lung CD1c(+) DCs from nonobstructed subjects to lungs of patients with COPDconfers tolerogenic properties. IL-27 and IL-10 levels are increased in the lung microenvironment on rhinovirus-induced COPD exacerbation invivo. We identify a novel tolerogenic circuit encompassing suppressive CD1c(+) DCs and regulatory T cells in patients with COPD that might be implicated in impaired respiratory immunity and further highlight IL-10 and IL-27 aspotent therapeutic targets.

Human Skin-Derived Precursor Cells Are Poorly Immunogenic and Modulate the Allogeneic Immune Response

Human skin-derived precursors (hSKPs) are multipotent somatic stem cells that persist within the dermis throughout adulthood and harbor potential clinical applicability. In this study, we investigated their immunogenicity and immunosuppressive features, both in vitro and in vivo. As such, this study provides a solid basis for developing their future clinical applications. We found that hSKPs express HLA-ABC molecules, but not HLA-DR, rendering them poorly immunogenic. Using a coculture set-up, we could further demonstrate that hSKPs inhibit the proliferation of allogeneic activated T cells and alter their cytokine secretion profile, in a dose-dependent manner. Cotransplantation of hSKP and human peripheral blood leukocytes (PBL) into severe combined immune-deficient mice also showed a significant impairment of the graft-versus-host response 1 week post-transplantation and a drastic increase in survival time of 60%. From a mechanistic point of view, we found that hSKPs require cell contact as well as secretion of soluble inhibitory factors in order to modulate the immune response. The expression/secretion levels of these factors further increases upon inflammation or in the presence of activated T cells. As such, we believe that these features could be beneficial in a later allogeneic clinical setting, because rejection of engrafted allogeneic hSKP might be delayed or even avoided due to their own promotion of a tolerogenic microenvironment.

Spatial and Temporal Changes In Geometries of Fluvial Channel Bodies From the Triassic Snadd Formation of Offshore Norway

Abstract During the Triassic, the Barents Sea Basin was gradually filled by a low-gradient prograding alluvial to deltaic plain, sourced from the Ural and Caledonian mountain belts in the southeast and stretching over 1000 km to Spitsbergen in the north. Progradation was made possible by high sediment yield and large trunk river systems on the scale of modern continental drainage systems. Analysis of six 3D seismic volumes from the southwest Barents Sea samples the Middle to Late Triassic Snadd Formation at various locations along an oblique depositional dip profile. By investigating spatial variability and stratigraphic evolution, this study reveals a variety of fluvial seismic geomorphological features, including point-bar systems and ribbon channel sandstone bodies. The fluvial part of the Snadd Formation is dominated by channel bodies up to 20 km wide that decrease in size to hundreds of meters over a distance of 300 km in a proximal–distal direction. There is a significant change in channel body geometries towards the top of the formation, with a decrease in maximum width from 20 to 5 km and maximum thickness from 58 to 40 m. In addition, there is an upward decrease in the channel-to-overbank ratio, and more elongated sandstone bodies have been identified in the upper part of the formation. Temporal changes are interpreted to reflect an allogenic response to changes in the hinterland, whereas spatial changes were governed by autogenic processes. This new regional understanding of the fluvial succession of the Snadd Formation provides insight into the architecture of ancient large-scale fluvial systems.