Induction Of Tolerance Research Articles

CD14highCD16+ monocytes are the main producers of Interleukin-10 following clinical heart transplantation.

Following heart transplantation, a cascade of immunological responses is initiated influencing the clinical outcome and long-term survival of the transplanted patients. The anti-inflammatory cytokine interleukin-10 (IL-10) was shown to be elevated in the blood of heart transplant recipients directly after transplantation but the releasing cell populations and the composition of lymphocyte subsets following transplantation have not been thoroughly studied. We identified immune cells by immunophenotyping and analyzed intracellular IL-10 production in peripheral blood mononuclear cells (PBMC) of heart transplanted patients (n= 17) before, directly after and 24h post heart transplantation. The cells were stimulated with lipopolysaccharide or PMA/Ionomycin to enhance cytokine production within leukocytes in vitro. We demonstrate that intermediate monocytes (CD14highCD16+), but not CD8+ T cells, CD4+ T cells, CD56+ NK cells or CD20+ B cells appeared to be the major IL-10 producers within patients PBMC following heart transplantation. Consequently, the absolute monocyte count and the ratio of intermediate monocytes to classical monocytes (CD14+CD16-) were specifically increased in comparison to pre transplant levels. Hence, this population of monocytes, which has not been in the focus of heart transplantation so far, may be an important modulator of clinical outcome and long-term survival of heart transplant recipients. Alteration of blood-circulating monocytes towards a CD14highCD16+ phenotype could therefore shift the pro-inflammatory immune response towards induction of graft tolerance, and may pave the way for the optimization of immunosuppression.

Induction of Tolerance in Groundnut Plants Against Drought Stress and Cercospora Leaf Spot Disease with Exogenous Application of Arginine and Sodium Nitroprusside Under Field Conditions

Naturally, under field conditions, plants are regularly experienced by a mixture of two or more stress factors. Drought is a major abiotic stress, and fungal pathogens characterize a main biotic stress challenge faced by plants and impact negatively on plant development and productivity. We propose that foliar application of nitric oxide (NO) donors can have positive effects on the induction of tolerance to biotic and abiotic stress on groundnut plants. This investigation was carried out to study the changes in growth, some biochemical aspects, and yield and quality of groundnut plants as well as induction of resistance to Cercospora leaf spot disease in response to nitric oxide (NO) donors, sodium nitroprusside (SNP), and arginine (Arg) (2.5, 5.0, and 7.5 mM) under two water irrigation levels 100% and 75% of water irrigation requirements (WIR), in two field experiments through two successive growing seasons of 2021 and 2022. Decreasing irrigation water significantly reduced shoot length, branches numberplant-1, shoot fresh and dry weight, photosynthetic pigments components, endogenous indole acetic acid (IAA) contents, and yield components. Furthermore, root fresh and dry weight, phenols, total soluble sugars (TSS), proline contents, and the accumulation of hydrogen peroxide (H2O2) and lipid peroxidation of groundnut leaves increased significantly. Contrarily, foliar application with Arg and SNP alleviated the negative influences of drought on growth and productivity of groundnut plants via enhancing photosynthetic pigments, IAA, phenolic compounds, TSS, and proline contents. Additionally, SNP and Arg significantly decreased oxidative damage through decreasing H2O2 and lipid peroxidation by the induction of antioxidant enzymes. Remarkably, the increase of drought level led to a reduction in Cercospora leaf spot (CLS) disease with the use of high concentrations of both Arg and SNP. Interestingly, in both stressed and unstressed plants, SNP treatment at 7.5 mM was the most effective in reducing the incidence and severity of disease, while Arg at 2.5 mM recorded the lowest reduction compared to other treatments. In conclusion, foliar treatment of either SNP or Arg is a profound effect on modulating the drought stress and induction of resistance to Cercospora leaf spot disease of groundnut plants throughout regulating physiological and biochemical processes associated with photosynthesis and oxidative responses.

Tolerogenic dendritic cells generated in vitro using a novel protocol mimicking mucosal tolerance mechanisms represent a potential therapeutic cell platform for induction of immune tolerance.

Dendritic cells (DCs) are mediators between innate and adaptive immunity and vital in initiating and modulating antigen-specific immune responses. The most important site for induction of tolerance is the gut mucosa, where TGF-β, retinoic acid, and aryl hydrocarbon receptors collaborate in DCs to induce a tolerogenic phenotype. To mimic this, a novel combination of compounds - the synthetic aryl hydrocarbon receptor (AhR) agonist IGN-512 together with TGF-β and retinoic acid - was developed to create a platform technology for induction of tolerogenic DCs intended for treatment of several conditions caused by unwanted immune activation. These in vitro-generated cells, designated ItolDCs, are phenotypically characterized by their low expression of co-stimulatory and activating molecules along with high expression of tolerance-associated markers such as ILT3, CD103, and LAP, and a weak pro-inflammatory cytokine profile. When co-cultured with T cells and/or B cells, ItolDC-cultures contain higher frequencies of CD25+Foxp3+ regulatory T cells (Tregs), CD49b+LAG3+ 'type 1 regulatory (Tr1) T cells, and IL-10-producing B cells and are less T cell stimulatory compared to cultures with matured DCs. Factor VIII (FVIII) and tetanus toxoid (TT) were used as model antigens to study ItolDC antigen-loading. ItolDCs can take up FVIII, process, and present FVIII peptides on HLA-DR. By loading both ItolDCs and mDCs with TT, antigen-specific T cell proliferation was observed. Cryo-preserved ItolDCs showed a stable tolerogenic phenotype that was maintained after stimulation with LPS, CD40L, or a pro-inflammatory cocktail. Moreover, exposure to other immune cells did not negatively impact ItolDCs' expression of tolerogenic markers. In summary, a novel protocol was developed supporting the generation of a stable population of human DCs in vitro that exhibited a tolerogenic phenotype with an ability to increase proportions of induced regulatory T and B cells in mixed cultures. This protocol has the potential to constitute the base of a tolDC platform for inducing antigen-specific tolerance in disorders caused by undesired antigen-specific immune cell activation.

Horse allergy: Curly Horses can mediate immune tolerance.

American Bashkir Curly Horses are claimed to be hypoallergenic, but this has not been clinically proven. In the present study, the effect of exposure to Curly Horses was investigated in 141 patients allergic to horses by measuring their lung function and nasal patency during Curly Horse contact. Continuous contact with Curly Horses, including riding and brushing, decreased the allergic riders' reactivity as measured by FEV1, PEF, and PNIF. Subsequent visits (up to 40 or more hours of riding) further reduced reactivity to the Curly Horses. Allergic events to horses occurred only in 72 out of 1312 riding hours, mainly in the first ten riding hours.In 41 out of the 141 patients, it was further investigated whether repeated exposure to Curly Horses could induce tolerance to other horses. Patients in the tolerance induction study were tested annually for horse allergy using a nasal provocation test. The tolerance induction study showed that exposure to Curly Horses induced immune tolerance to other horses in 88% of patients who completed the study.To understand the mechanism causing hypoallergenicity, we performed IgE immunoblots to determine whether Curly Horse hairs contain IgE binding proteins. However, no differences in IgE reactivity were found between Curly and non-Curly Horses. Moreover, the immune tolerance induction study patients did not show decreased IgE reactivity to hairs from Curly or non-Curly Horses even though patients had developed tolerance. However, we did find increasing levels of anti-horse IgG antibodies in the study patients.Overall, our data strongly suggests that continuous exposure to Curly Horses can induce immune tolerance, rendering these patients non-reactive to horses. The reason for the reduced clinical allergenicity of Curly Horses remains unclear, but the data suggest that blocking IgG antibodies may be of importance for immune tolerance development.

Advances in dendritic cell targeting nano-delivery systems for induction of immune tolerance.

Dendritic cells (DCs) are the major specialized antigen-presenting cells (APCs), play a key role in initiating the body's immune response, maintain the balance of immunity. DCs can also induce immune tolerance by rendering effector T cells absent and anergy, and promoting the expansion of regulatory T cells. Induction of tolerogenic DCs has been proved to be a promising strategy for the treatment of autoimmune diseases, organ transplantation, and allergic diseases by various laboratory researches and clinical trials. The development of nano-delivery systems has led to advances in situ modulation of the tolerance phenotype of DCs. By changing the material composition, particle size, zeta-potential, and surface modification of nanoparticles, nanoparticles can be used for the therapeutic payloads targeted delivery to DCs, endowing them with great potential in the induction of immune tolerance. This paper reviews how nano-delivery systems can be modulated for targeted delivery to DCs and induce immune tolerance and reviews their potential in the treatment of autoimmune diseases, organ transplantation, and allergic diseases.

Novel cell-based strategies for immunomodulation in vascularized composite allotransplantation.

Vascularized composite allotransplantation (VCA) has become a clinical reality in the past two decades. However, its routine clinical applications are limited by the risk of acute rejection, and the side effects of the lifelong immunosuppression. Therefore, there is a need for new protocols to induce tolerance and extend VCA survival. Cell- based therapies have emerged as an attractive strategy for tolerance induction in VCA. This manuscript reviews the current strategies and applications of cell-based therapies for tolerance induction in VCA. Cellular therapies, including the application of bone marrow cells (BMC), mesenchymal stem cells (MSC), adipose stem cells, regulatory T cells (Treg) cells, dendritic cells and donor recipient chimeric cells (DRCC) show promising potential as a strategy to induce tolerance in VCA. Ongoing basic science research aims to provide insights into the mechanisms of action, homing, functional specialization and standardization of these cellular therapies. Additionally, translational preclinical and clinical studies are underway, showing encouraging outcomes. Cellular therapies hold great potential and are supported by preclinical studies and clinical trials demonstrating safety and efficacy. However, further research is needed to develop novel cell-based immunosuppressive protocol for VCA.

Induction of long-term tolerance to a specific antigen using anti-CD3 lipid nanoparticles following gene therapy

Development of factor VIII (FVIII) inhibitors is a serious complication in the treatment of hemophilia A (HemA) patients. In clinical trials, anti-CD3 antibody therapy effectively modulates the immune response of allograft rejection or autoimmunediseases without eliciting major adverse effects. In this study, we delivered mRNA-encapsulated lipid nanoparticles (LNPs) encoding therapeutic anti-CD3 antibody (αCD3 LNPs) to overcome the anti-FVIII immune responses in HemA mice. It was found that αCD3 LNPs encoding the single-chain antibodies (Fc-scFv) can efficiently deplete CD3+ and CD4+ effector Tcells, whereas αCD3 LNPs encoding double-chain antibodies cannot. Concomitantly, mice treated with αCD3 (Fc-scFv) LNPs showed an increase in the CD4+CD25+Foxp3+ regulatory Tcell percentages, which modulated the anti-FVIII immune responses. All Tcells returned to normal levels within 2months. HemA mice treated with αCD3 LNPs prior to hydrodynamic injection of liver-specific FVIII plasmids achieved persistent FVIII gene expression without formation of FVIII inhibitors. Furthermore, transgene expression was increased and persistent following secondary plasmid challenge, indicating induction of long-term tolerance to FVIII. Moreover, the treated mice maintained their immune competence against other antigens. In conclusion, our study establisheda potential new strategy to induce long-term antigen-specific tolerance using an αCD3 LNP formulation.

Combining Treg Therapy With Donor Bone Marrow Transplantation: Experimental Progress and Clinical Perspective.

Donor-specific tolerance remains a goal in transplantation because it could improve graft survival and reduce morbidity. Cotransplantation of donor hematopoietic cells to achieve chimerism is a promising approach for tolerance induction, which was successfully tested in clinical trials. However, current protocols are associated with side effects related to the myelosuppressive recipient conditioning, which makes it difficult to introduce them as standard therapy. More recently, adoptive cell therapy with polyclonal or donor-specific regulatory T cells (Treg) proved safe and feasible in several transplant trials, but it is unclear whether it can induce tolerance on its own. The combination of both approaches-Treg therapy and hematopoietic cell transplantation-leads to chimerism and tolerance without myelosuppressive treatment in murine models. Treg therapy promotes engraftment of allogeneic hematopoietic cells, reducing conditioning requirements and enhancing regulatory mechanisms maintaining tolerance. This review discusses possible modes of action of transferred Treg in experimental chimerism models and describes translational efforts investigating the potent synergy of Treg and chimerism.

CTH1/TH2 repolarization in induction of immune tolerance to non-steroidal anti-inflammatory drugs during the management of sickle cell disease vaso-occlusive crisis

Respiratory manifestations related to the intake of non-steroidal anti-inflammatory drugs (NSAIDs) during the treatment of the painful vaso-occlusive crisis of sickle cell disease are either a type I hypersensitivity mechanism of the Gell and Coombs classification, or a pharmacological mechanism of NSAIDs. The use of NSAIDs is essential in the Abidjan school because of the absence of therapeutic alternatives in the management of the inflammatory crisis of this disease. The induction of tolerance to NSAIDs initiated by the authors has had clear clinical success. The basic biological reasons for this tolerance were evaluated in this study. A group of 11 sickle cell patients aged 12 to 39 years in whom post-NSAID respiratory manifestations disappeared for at least 6 months following a short tolerance induction protocol with ibuprofen, was assayed by ELISA for TNFα, INFg (Th1 cytokines), IL-4 (Th2 cytokine), IL-10, TGF-β (immunosuppressive cytokines) and total IgE, before induction or pre-induction (D-1) and at day one (D1), D2- 3, one month (M1), and M6 after induction. A repolarization of the Th1/Th2 balance was noted during the post induction period. The high concentration of IL-4 observed at D-1 gradually decreased in favor of the cytokines TNFα, INFg. The decrease in cytokine IL-4 with the level of total IgE was accompanied by the increase of IL-10 and TGF-β demonstrating the regulatory role of these cytokines in the control of allergic diseases. In conclusion, the induction of immuno-tolerance to NSAIDs through a short protocol is well supported by immune regulation. The medium-term effects are real, unlike the results of allergen desensitization or specific immunotherapy. However, this protocol could be used in certain circumstances such as in the case of intolerance to trimethoprim-sulfamethoxazole, used as the treatment of choice for the prevention of opportunistic diseases in people living with human immunodeficiency virus.

312.2: Combined double thymus transplantation and mixed xenogeneic chimerism for the induction of optimal tolerance and enhancement of immune function

312.2: Combined double thymus transplantation and mixed xenogeneic chimerism for the induction of optimal tolerance and enhancement of immune function

OC 44.2 Developing Humanized Mouse Models as a Testing Platform for Immune Tolerance Induction Therapy for Antibody-Positive Hemophilia a Patients

OC 44.2 Developing Humanized Mouse Models as a Testing Platform for Immune Tolerance Induction Therapy for Antibody-Positive Hemophilia a Patients

PB0658 Low-Dose Immune Tolerance Induction in Patients with Hemophilia A and Inhibitor Receiving Emicizumab Prophylaxis: Preliminary Results of the Brazilian Experience

PB0658 Low-Dose Immune Tolerance Induction in Patients with Hemophilia A and Inhibitor Receiving Emicizumab Prophylaxis: Preliminary Results of the Brazilian Experience

PB1322 Emicizumab Wastage Estimation for Treating People with Hemophilia A and Inhibitors who Failed Immune Tolerance Induction According to the Current Brazilian Public Health Protocol

PB1322 Emicizumab Wastage Estimation for Treating People with Hemophilia A and Inhibitors who Failed Immune Tolerance Induction According to the Current Brazilian Public Health Protocol

OC 50.1 Levels of IgG4 Distinguish Immune Tolerance Induction Outcome in Patients with Inherited Hemophilia A: Results from the BrazIT Study

OC 50.1 Levels of IgG4 Distinguish Immune Tolerance Induction Outcome in Patients with Inherited Hemophilia A: Results from the BrazIT Study

PB0649 Results from the RESIST Study for Tolerance Induction in Patients with Poor Prognosis for ITI Success

PB0649 Results from the RESIST Study for Tolerance Induction in Patients with Poor Prognosis for ITI Success

PB1306 Inhibitor Recurrence Following Immune Tolerance Induction in a Hemophilia A Patient with Inhibitor Post COVID-19 Infection

PB1306 Inhibitor Recurrence Following Immune Tolerance Induction in a Hemophilia A Patient with Inhibitor Post COVID-19 Infection

PB1288 Immune Tolerance Induction (ITI) Strategies in Haemophilia A Patients with Inhibitors - Data from the MOTIVATE Study

PB1288 Immune Tolerance Induction (ITI) Strategies in Haemophilia A Patients with Inhibitors - Data from the MOTIVATE Study

Immune tolerance induced in the anterior chamber ameliorates corneal transplant rejection

The relevance of regulatory T cells (Tregs) in induction of tolerance against corneal allografts has been well established. However, whether Tregs can be induced in the anterior chamber and suppress local alloimmune response after corneal transplantation is largely unknown. In the current study we report that not only can alloantigen specific Tregs be generated in the anterior chamber during corneal transplantation, they also play important roles in suppressing allograft rejection. Allograft rejected mice exhibit reduced Treg induction in the anterior chamber and the ability of aqueous humor and corneal endothelial cells from allograft rejected mice to induce Tregs is compromised. Further analysis revealed that the expression of immune-tolerance-related molecules is significantly decreased. Finally, we demonstrate that increasing Treg cells specifically in the anterior chamber can effectively suppress allograft rejection and exhibits better efficacy in promoting corneal allograft survival than systemic administration of Treg cells. Our current study may provide new ideas for the prevention and treatment of corneal transplant rejection.

Von Willebrand factor modulates immune complexes and the recall response against factor VIII in a murine hemophilia A model

AbstractAchieving tolerance toward factor VIII (FVIII) remains an important goal of hemophilia treatment. Up to 40% of patients with severe hemophilia A (HA) develop neutralizing antibodies against FVIII, and the only proven treatment to achieve tolerance is infusion of FVIII over prolonged periods in the context of immune tolerance induction. Here, we addressed the role of von Willebrand factor (VWF) as a modulator of anti-FVIII antibody effector functions and the FVIII-specific recall response in an HA mouse model. Analytical ultracentrifugation was used to demonstrate formation of FVIII-containing immune complexes (FVIII-ICs). VWF did not fully prevent FVIII-IC formation but was rather incorporated into larger macromolecular complexes. VWF prevented binding of FVIII-ICs to complement C1q, most efficiently when it was preincubated with FVIII before the addition of antibodies. It also prevented binding to immobilized Fc-γ receptor and to bone marrow–derived dendritic cells. An in vitro model of the anti-FVIII recall response demonstrated that addition of VWF to FVIII abolished the proliferation of FVIII-specific antibody-secreting cells. After adoptive transfer of sensitized splenocytes into immunocompetent HA mice, the FVIII recall response was diminished by VWF. In summary, these data indicate that VWF modulates the formation and effector functions of FVIII-ICs and attenuates the secondary immune response to FVIII in HA mice.

Interferon-γ priming enhances the therapeutic effects of menstrual blood-derived stromal cells in a mouse liver ischemia-reperfusion model.

Mesenchymal stem cells (MSCs) have been used in liver transplantation and have certain effects in alleviating liver ischemia-reperfusion injury (IRI) and regulating immune rejection. However, some studies have indicated that the effects of MSCs are not very significant. Therefore, approaches that enable MSCs to exert significant and stable therapeutic effects are worth further study. To enhance the therapeutic potential of human menstrual blood-derived stromal cells (MenSCs) in the mouse liver ischemia-reperfusion (I/R) model via interferon-γ (IFN-γ) priming. Apoptosis was analyzed by flow cytometry to evaluate the safety of IFN-γ priming, and indoleamine 2,3-dioxygenase (IDO) levels were measured by quantitative real-time reverse transcription polymerase chain reaction, western blotting, and ELISA to evaluate the efficacy of IFN-γ priming. In vivo, the liver I/R model was established in male C57/BL mice, hematoxylin and eosin and TUNEL staining was performed and serum liver enzyme levels were measured to assess the degree of liver injury, and regulatory T cell (Treg) numbers in spleens were determined by flow cytometry to assess immune tolerance potential. Metabolomics analysis was conducted to elucidate the potential mechanism underlying the regulatory effects of primed MenSCs. In vitro, we established a hypoxia/reoxygenation (H/R) model and analyzed apoptosis by flow cytometry to investigate the mechanism through which primed MenSCs inhibit apoptosis. Transmission electron microscopy, western blotting, and immunofluorescence were used to analyze autophagy levels. IFN-γ-primed MenSCs secreted higher levels of IDO, attenuated liver injury, and increased Treg numbers in the mouse spleens to greater degrees than untreated MenSCs. Metabolomics and autophagy analyses proved that primed MenSCs more strongly induced autophagy in the mouse livers. In the H/R model, autophagy inhibitors increased the level of H/R-induced apoptosis, indicating that autophagy exerted protective effects. In addition, primed MenSCs decreased the level of H/R-induced apoptosis via IDO and autophagy. Further rescue experiments proved that IDO enhanced the protective autophagy by inhibiting the mammalian target of rapamycin (mTOR) pathway and activating the AMPK pathway. IFN-γ-primed MenSCs exerted better therapeutic effects in the liver I/R model by secreting higher IDO levels. MenSCs and IDO activated the AMPK-mTOR-autophagy axis to reduce IRI, and IDO increased Treg numbers in the spleen and enhanced the MenSC-mediated induction of immune tolerance. Our study suggests that IFN-γ-primed MenSCs may be a novel and superior MSC product for liver transplantation in the future.