Pediatric Allergic Diseases, Food Allergy, and Oral Tolerance.

Pediatric allergic disease is a significant health concern worldwide, and the prevalence of childhood eczema, asthma, allergic rhinitis, and food allergy continues to increase. Evidence to support specific interventions for the prevention of eczema, asthma, and allergic rhinitis is limited, and no consensus on prevention strategies has been reached. Randomized controlled trials investigating the prevention of food allergy via oral tolerance induction and the early introduction of allergenic foods have been successful in reducing peanut and egg allergy prevalence. Infant weaning guidelines in the United Sates were recently amended to actively encourage the introduction of peanut for prevention of peanut allergy.

Race and ethnicity and the success of immune tolerance induction among people with severe haemophilia A in the United States.

INTRODUCTION: Immune tolerance induction (ITI) is the only treatment to eradicate inhibitors in people with severe haemophilia A with inhibitors. Since the risk of inhibitor development is greater among Black and Hispanic persons, it has been hypothesized that race and ethnicity may influence ITI success. Limited studies have evaluated this hypothesis. AIM: To examine the success of ITI according to race and ethnicity. METHODS: Participants who entered the Community Counts (CC) Registry between 2013 and 2017, were aged ≥3 years at study entry, and received ITI were included (n = 559). The proportion of participants with successful ITI was examined with adjusted prevalence ratios (aPRs) and corresponding 95% confidence intervals (95% CIs). RESULTS: Among 559 participants, 56.9%, 19.1%, 18.1% and 4.3% were Non-Hispanic (NH) White, NH Black, Hispanic and Asian, respectively, and 1.7% were coded as other or missing. Approximately 80% of Hispanic, NH Black and NH White participants had good/very good prognosis, defined as having a pre-ITI peak inhibitor of < 200 Bethesda Units per millilitre. Nearly 60% of participants (59.7%) achieved successful ITI, 20.7% and 19.5% experienced partially successful or failed ITI, respectively. Successful ITI was non-significantly lower in NH Black (54.2%; aPR = 0.95, 95% CI 0.62-1.44) and Hispanic (55.4%; aPR = 0.89, 95% CI 0.71-1.13) relative to NH White participants (62.6%). CONCLUSION: In this study, 60% of participants in the CC Registry had successful ITI, consistent with previous studies. The proportion with successful ITI was generally comparable across racial and ethnic groups with similar prognosis. These findings do not support the hypothesis that ITI response varies according to race or ethnicity.

Blood Transcriptomics Identifies Multiple Gene Expression Pathways Associated with the Clinical Efficacy of Hymenoptera Venom Immunotherapy.

Allergen-specific venom immunotherapy (VIT) is a well-established therapy for Hymenoptera venom allergy (HVA). However, the precise mechanism underlying its clinical effect remains uncertain. Our study aimed to identify the molecular mechanisms associated with VIT efficiency. We prospectively included 19 patients with HVA undergoing VIT (sampled before the beginning of VIT, after reaching the maintenance dose, one year after finishing VIT, and after a sting challenge) and 9 healthy controls. RNA sequencing of whole blood was performed on an Illumina sequencing platform. Longitudinal transcriptomic profiling revealed the importance of the inhibition of the NFκB pathway and the downregulation of DUX4 transcripts for the early protection and induction of tolerance after finishing VIT. Furthermore, successful treatment was associated with inhibiting Th2, Th17, and macrophage alternative signalling pathways in synergy with the inhibition of the PPAR pathway and further silencing of the Th2 response. The immune system became activated when reaching the maintenance dose and was suppressed after finishing VIT. Finally, successful VIT restores the immune system's balance to a state similar to that of healthy individuals. Our results underline the important role of the inhibition of four pathways in the clinical effect of VIT: Th2, Th17, NFκB, and macrophage signalling. Two biomarkers specific for successful VIT, regardless of the time of sampling, were C4BPA and RPS10-NUDT3 and should be further tested as potential biomarkers.

Induced pluripotent stem cell-derived hematopoietic stem and progenitor cells induce mixed chimerism and donor-specific allograft tolerance.

In transplantation using allogeneic induced pluripotent stem cells (iPSCs), strategies focused on major histocompatibility complexes were adopted to avoid immune rejection. We showed that minor antigen mismatches are a risk factor for graft rejection, indicating that immune regulation remains one of the most important issues. In organ transplantation, it has been known that mixed chimerism using donor-derived hematopoietic stem/progenitor cells (HSPCs) can induce donor-specific tolerance. However, it is unclear whether iPSC-derived HSPCs (iHSPCs) can induce allograft tolerance. We showed that 2 hematopoietic transcription factors, Hoxb4 and Lhx2, can efficiently expand iHSPCs with a c-Kit+Sca-1+Lineage- phenotype, which possesses long-term hematopoietic repopulating potential. We also demonstrated that these iHSPCs can form hematopoietic chimeras in allogeneic recipients and induce allograft tolerance in murine skin and iPSC transplantation. With mechanistic analyses, both central and peripheral mechanisms were suggested. We demonstrated the basic concept of tolerance induction using iHSPCs in allogeneic iPSC-based transplantation.

Factor IX inhibitors in haemophilia B: A report of National Haemophilia Registry in China.

INTRODUCTION: The development of inhibitors against factor FIX (FIX) is the most serious complication of FIX replacement therapy in haemophilia B (HB) patients. Currently, only few cohorts of HB inhibitor patients have been reported worldwide. AIM: This Chinese nationwide study of HB inhibitor patients explored their risk factors for FIX inhibitor development and experience on their management. METHODS: We retrospectively analysed patient characteristics, F9 genotypes, treatment strategies and outcomes of HB inhibitor patients registered to the Chinese National Registry and Patient Organization Registry. RESULTS: Forty-four unique HB inhibitor patients were identified in 4485 unique HB patients registered by year 2021 to the two Registries. Inhibitor diagnosis were usually delayed and the low prevalence (.98%) may suggest some inhibitor patients were not identified. Their median age at inhibitor diagnosis was 7.5 (IQR, 3.0-14.8) years. Most patients (95.5%) had high-titre inhibitors. Allergic/Anaphylactic reactions occurred in 59.1% patients. Large deletions and nonsense mutations were the most common F9 mutation types in our FIX inhibitor patients. Patients with large F9 gene deletions were more likely to develop inhibitors (p = .0002), while those with missense mutations had a low risk (p < .0001). Thirteen (29.5%) patients received immune tolerance induction (ITI) therapy using low-dose prothrombin complex concentrate regimens. Twelve completed ITI with three (25.0%) achieving success. Nephrotic syndrome developed in two (16.7%) patients during ITI. CONCLUSION: This study reports the largest Chinese cohort of HB inhibitor patients. Large deletions were most significantly associated with inhibitor development. Low-dose ITI might be feasible for FIX inhibitor eradication.

Novel Strategies in Transplantation: Genetic Engineering and Vascularized Composite Allotransplantation.

INTRODUCTION: Despite the clinical success in vascularized composite allotransplantation (VCA), systemic immunosuppression remains necessary to prevent allograft rejection. Even with potent immunosuppressive regimens (tacrolimus, mycophenolate mofetil, and steroids), most patients experience several rejection episodes, often within the same year. The risk of systemic side effects must constantly be weighed against the risk of under-immunosuppression and, thus, acute and chronic rejection. In this context, genomic editing has emerged as a potential tool to minimize the need for toxic immunosuppressive regimens and has gained attention in the fields of solid organ transplantation and xenotransplantation. This strategy may also be relevant for the future of VCA. METHODS: We discuss the topic of genetic engineering and review recent developments in this field that justify investigating tools such as clustered regularly interspaced short palindromic repeats/Cas9 in the context of VCA. RESULTS: We propose specific strategies for VCA based on the most recent gene expression data. This includes the well-known strategy of tolerance induction. Specifically, targeting the interaction between antigen-presenting cells and recipient-derived T cells by CD40 knockout may be effective. The novelty for VCA is a discovery that donor-derived T lymphocytes may play a special role in allograft rejection of facial transplants. We suggest targeting these cells prior to transplantation (e.g., by ex vivo perfusion of the transplant) by knocking out genes necessary for the long-term persistence of donor-derived immune cells in the allograft. CONCLUSION: Despite the demonstrated feasibility of VCA in recent years, continued improvements to immunomodulatory strategies using tools like clustered regularly interspaced short palindromic repeats/Cas9 could lead to the development of approaches that mitigate the limitations associated with rejection of this life-giving procedure.

Helical TomoTherapy Total Lymphoid Irradiation and Hematopoietic Cell Transplantation for Kidney Transplant Tolerance in Rhesus Macaques.

Development of a post-transplant kidney transplant tolerance induction protocol involving a novel total lymphoid irradiation (TLI) conditioning method in a rhesus macaque model is described. We examined the feasibility of acheiving tolerance to MHC 1-haplotype matched kidney transplants by establishing a mixed chimeric state with infusion of donor hematopoietic cells (HC) using TomoTherapy TLI. The chimeric state was hypothesized to permit the elimination of all immunosuppressive (IS) medications while preserving allograft function long-term without development of graft-versus-host-disease (GVHD) or rejection. An experimental group of 11 renal transplant recipients received the tolerance induction protocol and outcomes were compared to a control group (n = 7) that received the same conditioning but without donor HC infusion. Development of mixed chimerism and operational tolerance was accomplished in two recipients in the experimental group. Both recipients were withdrawn from all IS and continued to maintain normal renal allograft function for 4 years without rejection or GVHD. None of the animals in the control group achieved tolerance when IS was eliminated. This novel experimental model demonstrated the feasibility for inducing of long-term operational tolerance when mixed chimerism is achieved using a TLI post-transplant conditioning protocol in 1-haplotype matched non-human primate recipients of combined kidney and HC transplantation.

Tolerance Induction in Vascularized Composite Allotransplantation-A Brief Review of Preclinical Models.

Pre-clinical studies are an obligatory tool to develop and translate novel therapeutic strategies into clinical practice. Acute and chronic rejection mediated by the recipient's immune system remains an important limiting factor for the (long-term) survival of vascularized composite allografts (VCA). Furthermore, high intensity immunosuppressive (IS) protocols are needed to mitigate the immediate and long-term effects of rejection. These IS regiments can have significant side-effects such as predisposing transplant recipients to infections, organ dysfunction and malignancies. To overcome these problems, tolerance induction has been proposed as one strategy to reduce the intensity of IS protocols and to thereby mitigate long-term effects of allograft rejection. In this review article, we provide an overview about animal models and strategies that have been used to induce tolerance. The induction of donor-specific tolerance was achieved in preclinical animal models and clinical translation may help improve short and long-term outcomes in VCAs in the future.

A novel method to identify Post-Aire stages of medullary thymic epithelial cell differentiation.

Autoimmune regulator+ (Aire) medullary thymic epithelial cells (mTECs) play a critical role in tolerance induction. Several studies demonstrated that Aire+ mTECs differentiate further into Post-Aire cells. Yet, the identification of terminal stages of mTEC maturation depends on unique fate-mapping mouse models. Herein, we resolve this limitation by segmenting the mTEChi (MHCIIhi CD80hi ) compartment into mTECA/hi (CD24- Sca1- ), mTECB/hi (CD24+ Sca1- ), and mTECC/hi (CD24+ Sca1+ ). While mTECA/hi included mostly Aire-expressing cells, mTECB/hi contained Aire+ and Aire- cells and mTECC/hi were mainly composed of cells lacking Aire. The differential expression pattern of Aire led us to investigate the precursor-product relationship between these subsets. Strikingly, transcriptomic analysis of mTECA/hi , mTECB/hi , and mTECC/hi sequentially mirrored the specific genetic program of Early-, Late- and Post-Aire mTECs. Corroborating their Post-Aire nature, mTECC/hi downregulated the expression of tissue-restricted antigens, acquired traits of differentiated keratinocytes, and were absent in Aire-deficient mice. Collectively, our findings reveal a new and simple blueprint to survey late stages of mTEC differentiation.

National Survey of United Kingdom Paediatric Allergy Services.

BACKGROUND: Comprehensive national assessments of paediatric allergy services are rarely undertaken, and have never been undertaken in the United Kingdom. A 2006 survey estimated national capacity at 30,000 adult or paediatric new allergy appointments per year and identified 58 hospital clinics offering a paediatric allergy service. OBJECTIVE: The UK Paediatric Allergy Services Survey was the first comprehensive assessment of UK paediatric allergy service provision. METHODS: All 450 UK hospitals responded to a survey. Paediatric allergy services are provided in 154 lead hospitals with 75 further linked hospitals. All 154 lead paediatric allergy services completed a detailed questionnaire between February 2019 and May 2020. RESULTS: The 154 paediatric allergy services self-define as secondary (126/154, 82%) or tertiary (28/154, 18%) level services. The annual capacity is 85,600 new and 111,400 follow-up appointments. Fifty-eight percent (85/146) of services offer ≤10 new appointments per week (no data provided from 8 services-2 no response, 6 unknown) and 50% (70/139) of the services undertaking challenges undertake ≤2 food or drug challenges per week (no data from 3 challenge services). Intramuscular adrenaline is rarely used during challenges-median annual frequency 0 in secondary services and 2 in tertiary services. Allergen-specific immunotherapy is offered in 39% (60/154) of services, with 71% (41/58) of these centres treating ≤10 patients per annum (no data from 2 immunotherapy services). The 12 largest services see 31% of all new paediatric allergy appointments, undertake 51% of new immunotherapy patient provision and 33% of food or drug challenges. Seventy percent (97/126) of secondary and all tertiary services are part of a regional paediatric allergy network. Only nine services offer immunotherapy for any food (3 for peanut), 10 drug desensitization and 18 insect venom immunotherapy. CONCLUSIONS: There has been a fourfold increase in paediatric allergy clinics and an approximately sevenfold increase in new patient appointment numbers in the United Kingdom over the past 15 years. Most services are small, with significant regional variation in availability of specific services such as allergen immunotherapy. Our findings emphasize the need for national standards, local networks and simulation training to ensure consistent and safe service provision.

Care with allergen immunotherapy for allergic respiratory diseases in Germany-Predictors and deficits.

BACKGROUND: Allergen immunotherapy (AIT) represents the only possibility of causal therapy for allergic respiratory diseases. Although the prevailing high prevalence of allergic diseases and restrictions in the daily lives of patients, AIT is offered to a suboptimal number of patients in Germany. METHODS: Insured patients with documented allergic respiratory disease of one of the largest statutory health insurances in Germany, 'DAK-Gesundheit', were contacted by postal mail and asked to participate in the study. In case of written consent, primary and secondary data of patients were collected and analysed. Patient characteristics, predictors of being offered AIT, predictors of performing AIT and guideline-compliant care were analysed. RESULTS: 2505 subjects were included in the VerSITA study. Allergy to tree pollen and native speaking were identified as predictors, which increase the probability of being offered AIT. The probability was significantly decreased by the characteristics allergic rhinitis only, allergic asthma only, age in years, non-German citizenship, no graduation and lower secondary qualification. Significant positive predictors for an AIT to be actually performed were: Allergy to tree pollen and male sex. Predictors that decrease the likelihood that AIT is performed were: only allergic asthma, current smoker, former smoker, age and non-German citizenship. Furthermore, it was possible to identify characteristics in which guideline-compliant patients differed significantly from the rest of the study population. CONCLUSIONS: Based on statutory health insurance data and patient survey data, the VerSITA study provides a broad and in-depth overview of the care situation with regard to AIT in Germany and identifies deficits.

High-dose pollen intralymphatic immunotherapy: Two RDBPC trials question the benefit of dose increase.

BACKGROUND: The same dosing schedule, 1000 SQ-U times three, with one-month intervals, have been evaluated in most trials of intralymphatic immunotherapy (ILIT) for the treatment of allergic rhinitis (AR). The present studies evaluated if a dose escalation in ILIT can enhance the clinical and immunological effects, without compromising safety. METHODS: Two randomized double-blind placebo-controlled trials of ILIT for grass pollen-induced AR were performed. The first included 29 patients that had recently ended 3 years of SCIT and the second contained 39 not previously vaccinated patients. An up-dosage of 1000-3000-10,000 (5000 + 5000 with 30 minutes apart) SQ-U with 1 month in between was evaluated. RESULTS: Doses up to 10,000 SQ-U were safe after recent SCIT. The combined symptom-medication scores (CSMS) were reduced by 31% and the grass-specific IgG4 levels in blood were doubled. In ILIT de novo, the two first patients that received active treatment developed serious adverse reactions at 5000 SQ-U. A modified up-dosing schedule; 1000-3000-3000 SQ-U appeared to be safe but failed to improve the CSMS. Flow cytometry analyses showed increased activation of lymph node-derived dendritic but not T cells. Quality of life and nasal provocation response did not improve in any study. CONCLUSION: Intralymphatic immunotherapy in high doses after SCIT appears to further reduce grass pollen-induced seasonal symptoms and may be considered as an add-on treatment for patients that do not reach full symptom control after SCIT. Up-dosing schedules de novo with three monthly injections that exceeds 3000 SQ-U should be avoided.

Immune tolerance induction in the era of emicizumab - still the first choice for patients with haemophilia A and inhibitors?

INTRODUCTION: The development of inhibitory antibodies is a severe complication of clotting factor replacement therapy in patients with severe haemophilia A (HA). Current World Federation of Hemophilia (WFH) guidelines for haemophilia care indicate that eradication of inhibitors is best achieved through immune tolerance induction (ITI) therapy. AIM: The European Collaborative Haemophilia Network conducted a survey to determine whether ITI is still used in the routine management of patients with HA, and whether the availability of emicizumab prophylaxis has influenced treatment decisions. METHODS: The survey was conducted in late 2020/early 2021 in 18 centres representing 17 countries in the Europe/Middle East region treating a total of 4955 patients, and included sections specific to patient and centre demographics, treatment protocols (both ITI and prophylactic), inhibitor development and initiation of ITI, treatment success, and the incidence of adverse events. RESULTS: While our results indicate that ITI can still be considered a mainstay of treatment for patients with HA with inhibitors, less than daily dosing of ITI in combination with emicizumab prophylaxis is becoming commonplace across the spectrum of disease severity, with initiation being guided by bleeding patterns. The most frequently cited reasons for not initiating emicizumab prophylaxis were availability or reimbursement issues. CONCLUSION: ITI remains a mainstay for haemophilia treatment of patients with HA with inhibitors, but emicizumab has become a preferred first-line approach to protect against bleeds and represents an alternative to burdensome ITI in certain patient groups.

Eradication of FIX inhibitor in haemophilia B children using low-dose immune tolerance induction with rituximab-based immunosuppressive agent(s) in China.

INTRODUCTION: Development of haemophilia B inhibitors (HBI) results in the ineffectiveness of FIX replacement therapy. Inhibitor eradication by immune tolerance induction (ITI) is therefore necessary. In HBI, ITI even at high FIX dose is less effective and has a higher risk of severe complications. AIM: To characterize clinical features and outcome of ITI on HBI. METHODS: This retrospective study was conducted in Haemophilia Paediatric Comprehensive Care Centre of China. We used low-dose ITI (25-50 FIX IU/kg/three-times-weekly to every-other-day) with domestic prothrombin complex concentrate (PCC), combined with two successive immunosuppressive (IS) regimens. RESULTS: Sixteen HBI children, representing 5.7% of all and 14.4% of our severe registered HB patients, were enroled. Seven cases reported allergic reactions (ARs) proximal to inhibitor development. The historic peak inhibitor titre was median 54.2 (range 4.7-512) BU, and 15 (93.8%) had high-titre inhibitors. Twelve patients adherent to ITI were analysable. Of the nine ITI patients who received rituximab/prednisone (IS Regimen-1), four achieved tolerization in 1.4-43.3 months. Two subsequently relapsed but re-tolerized after a second course of IS Regimen-1. During ITI, the median treated bleed was .39/month (82.7% reduction from before ITI), and the incidence of AR and nephrotic syndrome (NS) complications was each at 22% (2/9). Three ITI patients received modified 'Beutel' protocol (IS Regimen-2) using multiple-IS-drugs, and two had rapid tolerization (.8 and 1.8 months). CONCLUSIONS: Inhibitor eradication could be achieved by low-dose ITI protocol using PCC combined with IS. Larger studies are needed to confirm if ITI with IS Regimen-2 is more effective with less complications.

Management of haemophilia A with inhibitors: A regional cross-talk.

INTRODUCTION: The development of inhibitors with factor VIII (FVIII) replacement therapy is one of the most common and challenging complications of haemophilia A (HA) treatment, jeopardising treatment efficacy and predisposing patients to high risks of morbidity and mortality. The management of patients with inhibitors is particularly challenging in countries where resources are limited. AIM: To provide a comprehensive summary of the management of HA with inhibitors while focusing on differences in practice between Western and non-Western countries and how resource scarcity can impact HA management, leading to suboptimal outcomes in patients with inhibitors. METHODS: Summary of key evidence and regional expert opinion. RESULTS: We address, particularly, the diagnosis of and testing for inhibitors, as well as the epidemiology of inhibitors, including incidence, prevalence and disease burden. Secondly, we provide an overview of the current treatment landscape in HA with inhibitors regarding the eradication of inhibitors with immune tolerance induction and the treatment and prevention of bleeding with bypassing agents, non-factor replacement agents and other experimental therapies. This is complemented with insights from the authors around the applicability of, and challenges associated with, such therapies in their settings of practice. CONCLUSIONS: We conclude by proposing some key steps towards bridging the gaps in the management of HA with inhibitors in resource-limited countries, including: (1) the collection of quality data that can inform healthcare reforms and policies; (2) improving disease knowledge among healthcare practitioners and patients with the aim of standardising disease management across centres and (3) working towards promoting equal access to HA care and therapies for everyone.

Low-dose immune tolerance induction therapy in children of Arab descent with severe haemophilia A, high inhibitor titres and poor prognostic factors for immune tolerance induction treatment success.

INTRODUCTION: Immune Tolerance Induction (ITI) is the first-choice therapy to eradicate Factor VIII (FVIII) neutralizing antibodies in patients with haemophilia A (HA). There is limited published data on ITI from East Mediterranean countries. AIM: To assess the effectiveness of a low-dose ITI regimen to eradicate FVIII neutralizing antibodies in children with severe HA and high-titre inhibitors. METHODS: A prospective, single-arm study was conducted in children with HA (FVIII < 1 IU/dl), high-titre inhibitors and poor prognostic factors for successful ITI. Patients were treated with ∼50 IU/kg plasma-derived FVIII containing von Willebrand factor (pdFVIII/VWF) concentrate (Koate-DVI, Grifols) three times a week. Time to achieve tolerance, total and partial success were analysed after ITI. Annual bleeding rate (ABR), number of target joints, FVIII recovery and school absence were compared before and after ITI. RESULTS: Twenty patients with median (range) age of 6.2 (3-12) years and pre-ITI inhibitor titre of 36.5 (12-169) BU were enrolled. ITI lasted ≤12 months (early tolerization) in 45% of patients. Median follow-up was 12 months (3-22) and total response rate was 80% (60% total success; 20% partial success). Patients with two and three poor prognosis factors achieved overall success rate of 60% and 50%, respectively. ABR, target joints and school absence were reduced after ITI by 60%, 50% and 44.1%, respectively. In successful ITI tolerized patients, FVIII recovery was 90 (60-100)%. CONCLUSION: A low-dose ITI therapy using a pdFVIII/VWF concentrate achieved at least partial tolerance in 80% of patients, and reduced annual bleeds in children with high inhibitor titres and at least one poor prognosis factor for ITI treatment success.

Biomarkers of immune tolerance in kidney transplantation: an overview.

Kidney failure, one of the most prevalent diseases in the world and with increasing incidence, is associated with substantial morbidity and mortality. Currently available modes of kidney replacement therapy include dialysis and kidney transplantation. Though kidney transplantation is the preferred and ideal mode of kidney replacement therapy, this modality, however, is not without its risks. Kidney transplant recipients are constantly at risk of complications associated with immunosuppression, namely, opportunistic infections (e.g., Epstein-Barr virus and cytomegalovirus infections), post-transplant lymphoproliferative disorder, and complications associated with immunosuppressants (e.g., calcineurin inhibitor- and corticosteroid-associated new onset diabetes after transplantation and calcineurin inhibitor-associated nephrotoxicity). Transplantation tolerance, an acquired state in which immunocompetent recipients have developed donor-specific unresponsiveness, may be the Holy Grail in enabling optimal allograft survival and obviating the risks associated with immunosuppression in kidney transplant recipients. This review aims to discuss the biomarkers available to predict, identify, and define the transplant immune tolerant state and various tolerance induction strategies. Regrettably, pediatric patients have not been included in any tolerance studies and this should be the focus of future studies.

PD-L1 overexpression conveys tolerance of mesenchymal stem cell-derived cardiomyocyte-like cells in an allogeneic mouse model.

Although the autologously transplanted cells are immunologically durable, allogeneic cell transplantation is inevitable in a series of cases. Mesenchymal stem cells (MSCs) are one of the suitable candidates for cardiac tissue regeneration that have been shown to acquire immunogenicity concurrent with cardiomyogenic differentiation. The present study aimed to exploit PD-L1, as a key immunomodulatory checkpoint ligand to protect the MSCs-derived cardiomyocyte-like cells (CLCs) against the detrimental alloimmunity. Mouse bone marrow-derived MSCs were stably transduced to overexpress PD-L1. MSCs were in vitro differentiated into CLCs and the expressions of immunologic molecules were compared between MSCs and CLCs. The in vitro and in vivo allogeneic immune responses were also examined. The differentiated CLCs had higher expressions of MHC-I and CD80. Upon in vitro coculture with allogeneic splenocytes, CLCs caused more CD4+ and CD8+ T cell activation, lymphocyte proliferation, and interferon-γ (IFN-γ) release in comparison to MSCs. PD-L1 overexpression on CLCs decreased the activation of CD8+ T cells, proliferation of lymphocytes, and release of IFN-γ. The PD-L1-overexpressing CLCs elicited lower in vivo CD4+ and CD8+ T cell activation and reduced the anti-donor antibody response accompanied by increased durability and reduced T cell infiltration. The present study verified the potential of PD-L1 overexpression as a preparative strategy for the protection of allogeneic MSCs-derived CLCs against the detrimental alloreaction.

Patients with haemophilia A with inhibitors in China: a national real-world analysis and follow-up.

The development of alloantibodies (inhibitors) against coagulation factor VIII (FVIII) is the most serious complication of FVIII replacement therapy in patients with haemophilia A (HA). We carried out a nationwide study focussing on patients with HA with inhibitors in China to evaluate the condition and management of this population. The study retrospectively analysed patient characteristics, clinical history, manifestation, treatment strategy as well as individual haemophilia care of 493 patients with inhibitors (466 with severe HA and 27 with non-severe HA) registered all over China. The median (interquartile range) age at diagnosis of FVIII inhibitors was 13 (5-28) years in patients with severe HA and 24 (10·5-39·5) years in patients with non-severe HA. Most patients (85%) had high-titre inhibitors. Prothrombin complex concentrate and recombinant activated coagulation factor VII were used respectively in 76·2% and 29·2% of patients for acute bleeding. Only 22·3% of patients underwent immune tolerance induction (ITI) treatment, of whom 64·9% achieved negative inhibitor titre. In patients who did not undergo ITI, the inhibitors turned negative in 17·7%, and patients with low peak inhibitor titre were more likely to acquire negative titre spontaneously (odds ratio 11·524, 95% confidence interval 5·222-25·432; P = 0·000). We recorded that 3·2% of the patients died from haemophilia-related life-threatening bleeding.

Preclinical development of plant-based oral immune modulatory therapy for haemophilia B.

Anti-drug antibody (ADA) formation is a major complication in treatment of the X-linked bleeding disorder haemophilia B (deficiency in coagulation factor IX, FIX). Current clinical immune tolerance protocols are often not effective due to complications such as anaphylactic reactions against FIX. Plant-based oral tolerance induction may address this problem, as illustrated by the recent first regulatory approval of orally delivered plant cells to treat peanut allergy. Our previous studies showed that oral delivery of plant cells expressing FIX fused to the transmucosal carrier CTB (cholera toxin subunit B) in chloroplasts suppressed ADA in animals with haemophilia B. We report here creation of the first lettuce transplastomic lines expressing a coagulation factor, in the absence of antibiotic resistance gene. Stable integration of the CTB-FIX gene and homoplasmy (transformation of ˜10 000 copies in each cell) were maintained in both T1 and T2 generation marker-free plants. CTB-FIX expression in lyophilized leaves of T1 and T2 marker-free plants was 1.0-1.5 mg/g dry weight, confirming that the marker excision did not affect antigen levels. Oral administration of CTB-FIX to Sprague Dawley rats at 0.25, 1 or 2.5 mg/kg did not produce overt adverse effects or toxicity. The no-observed-adverse-effect level (NOAEL) is at least 2.5 mg/kg for a single oral administration in rats. Oral administration of CTB-FIX at 0.3 or 1.47 mg/kg either mixed in food or as an oral suspension to Beagle dogs did not produce any observable toxicity. These toxicology studies should facilitate filing of regulatory approval documents and evaluation in haemophilia B patients.