Search

IntroductionIn pancreatic islet transplantation, the exact contribution of human leukocyte antigen (HLA) matching to graft survival remains unclear. Islets may be exposed to allogenic rejection but also the recurrence of type 1 diabetes (T1D). We evaluated the HLA-DR matching, including the impact of diabetogenic HLA-DR3 or HLA-DR4 matches.MethodsWe retrospectively examined the HLA profile in 965 transplant recipients and 2327 islet donors. The study population was obtained from patients enrolled in the Collaborative Islet Transplant Registry. We then identified 87 recipients who received a single-islet infusion. Islet-kidney recipients, 2nd islet infusion, and patients with missing data were excluded from the analysis (n=878).ResultsHLA-DR3 and HLA-DR4 were present in 29.7% and 32.6% of T1D recipients and 11.6% and 15.8% of the donors, respectively. We identified 52 T1D islet recipients mismatched for HLA-DR (group A), 11 with 1 or 2 HLA-DR-matches but excluding HLA-DR3 and HLA- DR4 (group B), and 24 matched for HLA-DR3 or HLA-DR4 (group C). Insulin-independence was maintained in a significantly higher percentage of group B recipients from year one through five post-transplantation (pConclusionThis study suggests that matching HLA-DR but excluding the diabetogenic HLA-DR3 and/or 4 is a significant predictor for long-term islet survival.

Novel biologics are currently being tested in clinical trials for the treatment of autoimmune diseases and the prevention of transplant allograft rejection. Their premise is to deliver highly efficient immunosuppression while minimizing side-effects, as they specifically target inflammatory mediators involved in the dysregulation of the immune system. However, the pleiotropism of soluble mediators and cell-to-cell interactions with potential to exert both proinflammatory and regulatory influences on the outcome of the immune response can lead to unpredictable results. Predicting responses to biologic drugs requires mechanistic understanding of the cell type-specific effect of immune mediators. Elucidation of the central role of regulatory T cells (Treg), a small subset of T cells dedicated to immune homeostasis, in preventing the development of auto- and allo-immunity has provided a deeper understanding of the signaling pathways that govern immune tolerance. This review focuses on the requisite signals that promote Treg homeostasis and discusses the anticipated outcomes of biologics targeting these signals. Our goal is to inform and facilitate the design of cell-specific biologics that thwart T effector cells (Teff) while promoting Treg function for the treatment of autoimmune diseases and the prevention of transplant rejection.

Atopy is a genetic condition predisposing individuals to develop immunoglobulin E (IgE) against common allergens through T-helper 2 (Th2) polarization mechanisms. The impact of atopy on graft survival in solid organ transplantation is unknown.We analyzed 268 renal allograft recipients from the Swiss Transplant Cohort Study, a prospective multicenter cohort studying patients after solid organ transplantation, with a 9-year median follow-up (IQR 3.0). We used the Phadiatop assay to measure IgE antibodies against a mixture of common inhaled allergens (grass, tree, herbs, spores, animals, and mites) to identify pre-transplantation atopic patients (0.35 KU/L).Of 268 kidney transplant recipients, 66 individuals were atopic (24.6%). Atopic patients were significantly younger than non-atopic patients (49.6 vs 58.0 years old, P = 0.002). No significant difference was found for gender, cold/warm ischemia time, preformed donor-specific antibodies (DSA), HLA mismatches, induction and maintenance immunosuppressive therapy, CMV serostatus, or cause of kidney failure. Patient and graft survival at ten years of follow-up were significantly better in the atopic group, 95.2% versus 69.2% patient survival (P0.001), and 87.9% versus 60.8% graft survival (P0.001), respectively. A multivariate Cox analysis revealed that atopy predicted recipient and graft survival independently of age and living donor donation. Finally, we found similar rates of biopsy-proven acute cellular and antibody-mediated rejections between atopic and non-atopic recipients.Atopy was associated with better long-term patient and graft survival, independently of age and living donor donation after kidney transplantation. Yet, atopy should not be used as a predictor for acute rejection.

Supplemental Digital Content is available in the text., Background. Metastatic carcinoma of a renal allograft is a rare but life threatening event with a difficult clinical management. Recent reports suggested a potential role of BK polyomavirus (BKPyV) in the development of urologic tract malignancies in kidney transplant recipients. Methods. We investigated a kidney-pancreas female recipient with an history of BKPyV nephritis who developed a rapidly progressive and widely metastatic donor-derived renal carcinoma 9 years after transplantation. Results. Histology and fluorescence in situ hybridization analysis revealed a donor-derived (XY tumor cells) collecting (Bellini) duct carcinoma. The presence of BKPyV oncogenic large tumor antigen was identified in large amount within the kidney tumor and the bowel metastases. Whole genome sequencing of the tumor confirmed multiple genome BKPyV integrations. The transplanted kidney was removed, immunosuppression was withdrawn, and recombinant interleukin-2 (IL-2) was administered for 3 months, inducing a complete tumor clearance, with no evidence of disease at 6-year follow-up. The immunological profiling during IL-2 therapy revealed the presence of donor-specific T cells and expanded cytokine-producing bright natural killer cells but no donor-specific antibodies. Finally, we found persistently elevated anti-BK virus IgG titers and a specific anti-BKPyV T cell response. Conclusions. This investigation showed evidence for the potential oncogenic role of BKPyV in collecting duct carcinoma in renal allografts and demonstrated that immunosuppression withdrawal and IL-2 therapy can lead to an efficient antitumor cellular mediated rejection possibly via 3 distinct mechanisms including (1) host-versus-graft, (2) host-versus-tumor, and (3) anti-BKPyV responses.

The success of pancreas islet isolation largely depends on donor characteristics, including extracellular matrix composition of which collagen is the main element. We hypothesized that isolation yields are proportional to collagen digestion percentage, and aimed to determine a threshold that predicts isolation success. The amount of pancreas collagen (I-V) was determined using colorimetry prior to and after the digestion process in 52 human islet isolations. Collagen I-V and VI were also assessed histologically. We identified a collagen digestion threshold of ≥ 60% as an independent factor beyond which an islet preparation has a ninefold increased odds of yielding ≥ 250 000 islet equivalents (IEQ) (P = 0.009) and a sixfold increased odds of being transplanted (P = 0.015). Preparations with ≥ 60% collagen digestion (n = 35) yielded 283 017 ± 164 214 IEQ versus 180 142 ± 85 397 in the < 60% collagen digestion group (n = 17) (P = 0.016); respectively 62.9% versus 29.4% of those were transplanted (P = 0.024). Common donor characteristics, initial collagen content, enzyme blend, and digestion times were not associated with collagen digestion percentage variations. Donor age positively correlated with the amount of collagen VI (P = 0.013). There was no difference in islet graft survival between high and low digestion groups. We determined that a 60% pancreas collagen digestion is the threshold beyond which an islet isolation is likely to be successful and transplanted.

Organ allotransplantation has now reached an impassable ceiling inherent to the limited supply of human donor organs. In the United States, there are currently over 100,000 individuals on the national transplant waiting list awaiting a kidney, heart, and/or liver transplant. This is in contrast with only a fraction of them receiving a living or deceased donor allograft. Given the morbidity, mortality, costs, or absence of supportive treatments, xenotransplant has the potential to address the critical shortage in organ grafts. Last decade research efforts focused on creation of donor organs from pigs with various genes edited out using CRISPR technologies and utilizing non-human primates for trial. Three groups in the United States have recently moved forward with trials in human subjects and obtained initial successful results with pig-to-human heart and kidney xenotransplantation. This review serves as a brief discussion of the recent progress in xenotransplantation research, particularly as it concerns utilization of porcine heart, renal, and liver xenografts in clinical practice.

Intravenous iron infusions rarely result in severe hypersensitivity reactions. The primary suspected hypersensitivity mechanism is an abnormal complement activation by non-IgE antibodies to the carbohydrate moieties stabilizing iron formulations. A major risk factor for hypersensitivity reactions is related to the infusion speed. Fishbane-like reactions usually resolve after pausing the infusion, which can be resumed under medical surveillance and at a lower infusion rate. Yet, anaphylactic reactions require emergency first aid and subsequent strict avoidance of intravenous iron. Desensitization protocols can be implemented in selected cases and under strict medical surveillance to reduce the risks of severe reactions upon re-exposure.L’administration de fer intraveineux (IV) peut rarement se compliquer de réactions d’hypersensibilités sévères, parfois fatales. Le mécanisme supposé est celui d’une activation anormale du complément, possiblement liée à des anticorps non-IgE (immunoglobuline E) dirigés contre les groupements carbohydrates qui stabilisent la formulation de fer. Un débit de perfusion trop rapide est un facteur important de réaction d’hypersensibilité. En effet, les réactions légères se résolvent généralement après mise en pause de la perfusion, qui peut ensuite être reprise à un débit réduit. Les réactions anaphylactiques nécessitent en revanche un traitement d’urgence et une éviction stricte. Le recours à un protocole de désensibilisation sous surveillance médicale étroite permet, dans certaines situations, de limiter le risque de réaction lors d’une réadministration de fer IV.

Anisakis simplex is a parasitic worm. It infects marine mammals that feed on fish and cephalopods, its intermediary hosts. Human disease is caused by accidental ingestion of Anisakis larvae. Upon consumption of contaminated fish, cuttlefish or squid, human may develop two distinct clinical pictures: Anisakiasis is provoked by living larvae penetrating the digestive mucosa. Allergy is caused by IgE-mediate hypersensitivity to living or dead larvae in a previously sensitized individual. Anisakiasis may manifests with violent epi gastric pain, acute abdomen or eosinophilic gastroenteritis. The larvae may be visualized by endoscopy or histology. The main Anisakis allergens are not denaturated by heat or cold and resist to digestion. Allergy diagnosis relies on careful history and detection of specific IgE.

Beta-lactam allergy is a common problem in everyday medical practice and is recognized as a major public health issue. Carrying this label frequently leads to the avoidance of all beta-lactam antibiotics, favoring the use of other less preferred classes of antibiotics, that are more expensive and associated with more side effects and increased antimicrobial resistance. Therefore, delabeling a beta-lactam allergy is part of antimicrobial stewardship programs. Herein, we retrospectively examined the clinical records of 576 patients who were referred to our center for a label of allergy to beta-lactam antibiotics and were systematically investigated following a standardized algorithm. Our main aim was to evaluate the frequency of confirmed immediate- and delayed-type allergy to commonly prescribed subclasses of beta-lactam antibiotics (penicillin and cephalosporin), as well as the negative predictive value (NPV) and the sensitivity of skin tests. Our secondary aims were to examine the safety of beta-lactam skin testing and drug challenge. We identified that 260 patients reported a history of immediate reactions, 131 of delayed reactions, and 114 of unknown timing or mechanism of reactions. Following assessment and testing, 86 (18.3%) patients had a confirmed allergy to any beta-lactam antibiotics; 63 (13.4%) with an immediate- and 23 (4.9%) with a delayed-type reaction. Most frequently identified confirmed allergy was to penicillins (65 patients), followed by cephalosporins (21 patients). When immediate-type reactions were examined, NPV of skin tests were 96.3% and 100% for penicillins and cephalosporins, respectively. When delayed reactions were considered, NPV were 91.9 and 87.5% for penicillins and cephalosporins, respectively. Evaluation of the safety of skin tests according to the standardized procedure showed that systemic allergic reactions occurred in only 0.7% of skin tests and in 3.1% of drug challenges. Overall, our data indicate that only 18.3% of patients with a beta-lactam allergy label have a confirmed allergy and non-allergic patients can be safely delabeled through allergic workup based on skin tests and drug challenge. This approach supports the policy of saving second-line antibiotics through a standardized allergy workup.

This cohort study examines the association of the COVID-19 vaccine booster with chronic spontaneous urticaria in Swiss patients.

Treg therapies are being tested in clinical trials in transplantation and autoimmune diseases, however, the impact of inflammation on Tregs remains controversial. We challenged human Tregsex-vivowith pro-inflammatory cytokines IL-6 and TNFαand observed greatly enhanced proliferation stimulated by anti-CD3 and anti-CD28 (aCD3/28) beads or CD28 superagonist (CD28SA). The cytokine-exposed Tregs maintained high expression of FOXP3 and HELIOS, demethylated FOXP3 enhancer, and low IFNγ, IL-4, and IL-17 secretion. Blocking TNF receptor using etanercept or deletion ofTNF receptor 2using CRISPR/Cas9 blunted Treg proliferation and attenuated FOXP3 and HELIOS expression. These results prompted us to consider using CD28SA together with IL-6 and TNFαwithout aCD3/28 beads (beadless) as an alternative protocol for therapeutic Treg manufacturing. Metabolomics profiling revealed more active glycolysis and oxidative phosphorylation, increased energy production, and higher antioxidant potential during beadless Treg expansion. Finally, beadless expanded Tregs maintained suppressive functionsin vitroandin vivo. These results demonstrate that human Tregs positively respond to proinflammatory cytokines with enhanced proliferation without compromising their lineage identity or function. This property can be harnessed for therapeutic Treg manufacturing.

The newly developed mRNA-based COVID-19 vaccines can provoke anaphylaxis, possibly induced by polyethylene glycol (PEG) contained in the vaccine. The management of persons with a history of PEG allergy or with a suspected allergic reaction after the first dose remains to be defined.In this real-life study, we defined two cohorts of individuals: one pre-vaccination including 187 individuals with high-risk profiles for developing anaphylaxis and a second post-vaccination including 87 individuals with suspected allergic reactions after the COVID-19 mRNA vaccine. Upon negative skin test with an mRNA vaccine, a two-step (10-90%) vaccination protocol was performed. Positive skin tests were confirmed with the basophil activation test (BAT).Among 604,267 doses of vaccine, 87 suspected allergic reactions (5 after the booster) were reported to our division for further investigations: 18/87 (21%) were consistent with anaphylaxis, 78/87 (90%) were female, and 47/87 (54%) received the BNT162b2 mRNA vaccine. Vaccine skin tests were negative in 96% and 76% of the pre- and post-vaccination cohorts, respectively. A two-step vaccination was tolerated in 232/236 (98%) of individuals with negative tests. Four individuals experienced isolated asthmatic reactions during the two-step challenge. Vaccine-positive skin tests were consistently confirmed by BAT; CD63 and CD203c expression was selectively inhibited with ibrutinib, suggesting an IgE-dependent mechanism.Sensitization to SARS-CoV-2 mRNA vaccines can be detected with intradermal testing. Significantly more individuals were sensitized to mRNA vaccines in the post-vaccination cohort. A two-step 10-90%-vaccination protocol can be safely administered upon negative skin testing.

Infusion of regulatory T cells (Tregs) engineered with a chimeric antigen receptor (CAR) targeting donor-derived human leukocyte antigen (HLA) is a promising strategy to promote transplant tolerance. Here, we describe an anti-HLA-A2 CAR (A2-CAR) generated by grafting the complementarity-determining regions (CDRs) of a human monoclonal anti-HLA-A2 antibody into the framework regions of the Herceptin 4D5 single-chain variable fragment and fusing it with a CD28-ζ signaling domain. The CDR-grafted A2-CAR maintained the specificity of the original antibody. We then generated HLA-A2 mono-specific human CAR Tregs either by deleting the endogenous T-cell receptor (TCR) via CRISPR/Cas9 and introducing the A2-CAR using lentiviral transduction or by directly integrating the CAR construct into the TCR alpha constant locus using homology-directed repair. These A2-CAR+TCRdeficient human Tregs maintained both Treg phenotype and function in vitro. Moreover, they selectively accumulated in HLA-A2-expressing islets transplanted from either HLA-A2 transgenic mice or deceased human donors. A2-CAR+TCRdeficient Tregs did not impair the function of these HLA-A2+ islets, whereas similarly engineered A2-CAR+TCRdeficientCD4+ conventional T cells rejected the islets in less than 2 weeks. A2-CAR+TCRdeficient Tregs delayed graft-versus-host disease only in the presence of HLA-A2, expressed either by co-transferred peripheral blood mononuclear cells or by the recipient mice. Altogether, we demonstrate that genome-engineered mono-antigen-specific A2-CAR Tregs localize to HLA-A2-expressing grafts and exhibit antigen-dependent in vivo suppression, independent of TCR expression. These approaches may be applied towards developing precision Treg cell therapies for transplant tolerance.

Treg therapy is being tested in clinical trials in transplantation and autoimmune diseases, however, the impact of inflammation on Tregs is unclear. In this study, we challenged human Tregs ex-vivo with pro-inflammatory cytokines, TNFα and IL-6. These cytokines enhanced Treg proliferation induced by anti-CD3 and anti-CD28 or CD28 superagonist (CD28SA) while maintaining high expression of FOXP3 and HELIOS, demethylated FOXP3 enhancer, and low expression of cytokines IFNg, IL-4 and IL-17. Blocking TNF receptor signaling using etanercept or deletion of TNF receptor 2 using CRISPR/Cas9 blunted Treg proliferation and attenuated FOXP3 and HELIOS expression, revealing the importance of TNFR2 signaling in Treg proliferation and lineage stability. The robust proliferation induced by CD28SA with IL-6 and TNFα may be adopted for the expansion of therapeutic Tregs. Metabolomics analysis showed that Tregs expanded with CD28SA plus cytokines had more active glycolysis and oxidative phosphorylation, increased energy production, and higher antioxidant potential. Finally, CD28SA plus cytokine-expanded Tregs had comparable suppressive activity in vitro and in vivo in a humanized mouse model of graft-versus-host-disease when compared to Tregs expanded using the conventional protocol. These results demonstrate that human Tregs positively respond to proinflammatory cytokines with enhanced proliferation without compromising their lineage identity or function.

Cannabis-fruit and vegetable syndrome is of recent discovery and linked to lipid transfer protein (LTP) sensitization. It is thought that the primary sensitization originates from the cannabis LTP (Can s 3). Sensitized patients can cross-react to others LTP homologs such as peach LTP (Pru p 3). Diagnosis may be challenging, as consumption of cannabis is often omitted by the patient and needs to be specifically addressed during the interview. Thus, meticulous history taking is mandatory. Laboratory workup includes LTP-specific IgE and skin testing. Management relies on allergen eviction.Le syndrome cannabis-fruits et légumes est une forme d’allergie croisée récemment découverte et semble liée à une sensibilisation aux protéines de transfert lipidique (LTP, Lipid Transfer Protein). Il est supposé que la sensibilisation primaire intervienne par la LTP du cannabis. Les sujets sensibilisés sont ensuite à risque de réagir à d’autres LTP, comme celle de la pêche, mais pas uniquement. Le diagnostic est souvent fastidieux du fait de la méconnaissance de cette entité par le clinicien et de la réticence des patients à parler de leur consommation de cannabis. Le diagnostic repose sur une anamnèse détaillée, des tests cutanés avec les allergènes suspectés et la recherche d’immunoglobulines E spécifiques contre les LTP. Le traitement consiste en l’éviction du cannabis et des fruits et légumes responsables de symptômes.

Anti-CD19 chimeric antigen receptor (CD19-CAR)-engineered T cells are approved therapeutics for malignancies. The impact of the hinge domain (HD) and the transmembrane domain (TMD) between the extracellular antigen-targeting CARs and the intracellular signaling modalities of CARs has not been systemically studied. In this study, a series of 19-CARs differing only by their HD (CD8, CD28, or IgG4) and TMD (CD8 or CD28) was generated. CARs containing a CD28-TMD, but not a CD8-TMD, formed heterodimers with the endogenous CD28 in human T cells, as shown by co-immunoprecipitation and CAR-dependent proliferation of anti-CD28 stimulation. This dimerization was dependent on polar amino acids in the CD28-TMD and was more efficient with CARs containing CD28 or CD8 HD than IgG4-HD. The CD28-CAR heterodimers did not respond to CD80 and CD86 stimulation but had a significantly reduced CD28 cell-surface expression. These data unveiled a fundamental difference between CD28-TMD and CD8-TMD and indicated that CD28-TMD can modulate CAR T-cell activities by engaging endogenous partners.

BACKGROUND Xenotransplantation has made tremendous progress over the last decade. METHODS We discuss kidney and heart xenotransplantation, which are nearing initial clinical trials. RESULTS Life sustaining genetically modified kidney xenografts can now last for approximately 500 days and orthotopic heart xenografts for 200 days in non-human primates. Anti-swine specific antibody screening, preemptive desensitization protocols, complement inhibition and targeted immunosuppression are currently being adapted to xenotransplantation with the hope to achieve better control of antibody-mediated rejection (AMR) and improve xenograft longevity. These newest advances could probably facilitate future clinical trials, a significant step for the medical community, given that dialysis remains difficult for many patients and can have prohibitive costs. Performing a successful pig-to-human clinical kidney xenograft, that could last for more than a year after transplant, seems feasible but it still has significant potential hurdles to overcome. The risk/benefit balance is progressively reaching an acceptable equilibrium for future human recipients, e.g. those with a life expectancy inferior to two years. The ultimate question at this stage would be to determine if a "proof of concept" in humans is desirable, or whether further experimental/pre-clinical advances are still needed to demonstrate longer xenograft survival in non-human primates. CONCLUSION In this review, we discuss the most recent advances in kidney and heart xenotransplantation, with a focus on the prevention and treatment of AMR and on the recipient's selection, two aspects that will likely be the major points of discussion in the first pig organ xenotransplantation clinical trials.

PURPOSE OF REVIEW Cell-based immunotherapies have made enormous progress over the last decade with the approval of several anti-CD19-chimeric antigen receptor (CAR)-T cell therapies for haemato-oncological diseases. CARs are synthetic receptors comprising an antigen-specific extracellular domain fused to a hinge, transmembrane and intracellular signalling domains. The success obtained with CD19 CAR-T cells rekindled interest in using CAR-T cells to treat HIV seropositive patients. The purpose of this review is to discuss historical and recent developments of anti-HIV CARs. RECENT FINDINGS Since the first description of CD4+-based CARs in the early 90s, new generations of anti-HIV CARs were developed. They target the hetero-trimeric glycoprotein gp120/gp41 and consist of either a CD4+ extracellular domain or a VH/VL segment derived from broadly neutralizing antibodies. Recent efforts were employed in multiplexing CAR specificities, intracellular signalling domains and T cells resistance to HIV. SUMMARY Several new-anti HIV CAR-T cells were successfully tested in preclinical mice models and are now waiting to be evaluated in clinical trials. One of the key parameters to successfully using CAR-T cells in HIV treatment will depend on their capacity to control the HIV reservoir without causing off-targeting activities.

Anti-CD19 chimeric antigen receptor (CD19-CAR)-engineered T cells are approved therapeutics for malignancies. The impact of the hinge (HD) and transmembrane (TMD) domains between the extracellular antigen-targeting and the intracellular signaling modalities of CARs has not been systemically studied. Here, a series of CD19-CARs differing only by their HD (CD8/CD28/IgG4) and TMD (CD8/CD28) was generated. CARs containing a CD28-TMD, but not a CD8-TMD, formed heterodimers with the endogenous CD28 in human T cells, as shown by co-immunoprecipitation and CAR-dependent proliferation to anti-CD28 stimulation. This dimerization depended on polar amino-acids in the CD28-TMD. CD28-CAR heterodimerization was more efficient in CARs containing a CD8-HD or CD28-HD as compared to an IgG4-HD. CD28-CAR heterodimers did not respond to CD80 and CD86 stimulation but led to a significant reduction of CD28 cell-surface expression. These data unveil a new property of the CD28-TMD and suggest that TMDs can modulate CAR T-cell activities by engaging endogenous partners.Abstract Figure

Forkhead box P3-expressing regulatory T (Treg) cells are essential for self-tolerance, with an emerging role in tissue repair and regeneration. Their ability to traffic to tissue and perform complex therapeutic tasks in response to the tissue microenvironment make them an attractive candidate for drug development. Early experiences of Treg cell therapy in patients with graft-versus-host disease, type 1 diabetes, and organ transplantation have shown that it is feasible, safe, and potentially efficacious in some settings. Many ongoing trials in patients with a wide variety of diseases will further enhance our knowledge about the optimal approaches for Treg cell manufacturing and dosing. We review the current preclinical rationale supporting Treg cell therapy in a variety of disease settings ranging from tissue transplantation, autoimmune diseases, and non-immune-mediated inflammatory settings. We point out challenges in development of Treg cell therapy and speculate how synthetic biology can be used to enhance the feasibility and efficacy of Treg cell therapy for autoimmune and autoinflammatory diseases.

Background Tolerogenic dendritic cells (DCs) represent a promising approach to promote transplantation tolerance. In this study, the potential of autologous bone marrow (BM)-derived murine DC to protect rat-to-mouse islets xenografts was analyzed. Methods Tolerogenic DCs were generated by differentiating BM cells in the presence of granulocyte-macrophage colony-stimulating factor and interleukin 10 (IL-10, IL-10 DC). The phenotype of IL-10 DC was characterized in vitro by expression of costimulatory/inhibitory molecules (flow cytometry) and cytokines (Luminex and ELISA), their function by phagocytosis and T-cell stimulation assays. To study transplant tolerance in vivo, rat islets were transplanted alone or in combination with autologous murine IL-10 DC under the kidney capsule of streptozotocin-induced diabetic C57BL/6 mice. Xenograft survival was evaluated by monitoring glycemia, cellular infiltration of xenografts by microscopy and flow cytometry 10 days post-transplantation. Results Compared with control DC, IL-10 DC exhibited lower levels of major histocompatibility complex class II, costimulatory molecules (CD40, CD86, CD205), lower production of pro-inflammatory cytokines (IL-12p70, TNF, IL-6), and higher production of IL-10. Phagocytosis of xenogeneic rat splenocytes was not impaired in IL-10 DC, whereas stimulation of T-cell proliferation was reduced in the presence of IL-10 DC. Xenograft survival of rat islets in diabetic mice co-transplanted with autologous murine IL-10 DC was significantly prolonged from 12 to 21 days, without additional immunosuppressive treatment. Overall, infiltration of xenografts by T cells and myeloid cells was not different in IL-10 DC recipient mice, but enriched for CD8+ T cells and myeloid cells with suppressor-associated phenotype. Conclusions Autologous IL-10-differentiated DC with tolerogenic properties prolong rat-to-mouse islets xenograft survival, potentially by locally inducing immune regulatory cells, indicating their potential for regulatory immune cell therapy in xenotransplantation.

Regulatory T cells (Treg cells) are a small subset of immune cells that are dedicated to curbing excessive immune activation and maintaining immune homeostasis. Accordingly, deficiencies in Treg cell development or function result in uncontrolled immune responses and tissue destruction and can lead to inflammatory disorders such as graft-versus-host disease, transplant rejection and autoimmune diseases. As Treg cells deploy more than a dozen molecular mechanisms to suppress immune responses, they have potential as multifaceted adaptable smart therapeutics for treating inflammatory disorders. Indeed, early-phase clinical trials of Treg cell therapy have shown feasibility, tolerability and potential efficacy in these disease settings. In the meantime, progress in the development of chimeric antigen receptors and in genome editing (including the application of CRISPR–Cas9) over the past two decades has facilitated the genetic optimization of primary T cell therapy for cancer. These technologies are now being used to enhance the specificity and functionality of Treg cells. In this Review, we describe the key advances and prospects in designing and implementing Treg cell-based therapy in autoimmunity and transplantation. Our increased understanding of how regulatory T cells suppress immune responses has led to their use in early-phase clinical trials for inflammatory disorders, with promising results. This Review describes the key advances and prospects in designing and implementing regulatory T cells as multifaceted, adaptable smart therapeutics in autoimmunity and transplantation.

Background & Aims Hereditary haemorrhagic telangiectasia is characterized by arterio-venous malformations (AVM). It frequently involves the liver without clinical symptoms, but may lead to biliary ischaemia, portal hypertension, or fatal high-output heart failure. The indication of liver transplantation is controversial. Methods Herein, we report the case of a 65-year-old female patient with a ‘double Osler syndrome’ consisting of hereditary haemorrhagic telangiectasia (HHT) and type I hereditary angioedema diagnosed at the age of 25 and 22 years respectively. Results Hereditary angioedema was treated with danazol for several decades until multiple hypoechogenic liver masses were detected. Albeit danazol treatment was replaced by C1 esterase inhibitor infusions, hepatocellular carcinoma was diagnosed at the age of 64 and the patient was listed for liver transplantation. HHT was marked by recurrent epistaxis until the age of 63 when severe intestinal bleeding occurred. At the age of 65, severe dyspnoea (NYHA class IV) developed and rapidly progressive high-output cardiac failure was diagnosed. Despite argon plasma coagulation to control bleeding from intestinal angiodysplasia, and treatment with bevacizumab to inhibit angiogenesis, the patient died from severe gastrointestinal bleeding associated with cardiogenic shock at the age of 66 before being transplanted. Conclusion The indication to list this patient for liver transplantation was debated several times before the diagnosis of hepatocellular carcinoma because of good general condition and low MELD score. Precise guidelines for screening and management of patients with hepatic HHT need to be better defined.

This manuscript presents quantitative findings on the actual effectiveness of terminal complement component 5 (C5) inhibitors and complement component 1 (C1) esterase inhibitors through their formal and common &ldquo, off-label&rdquo, (compassionate) indications. The results emanated from pairwise and network meta-analyses to present evidence until September 2019. Clinical trials (CT) and real-life non-randomized studies of the effects of interventions (NRSI) are consistent on the benefits of C5 inhibitors and of the absence of effects of C1 esterase inhibitors (n = 7484): Mathematically, eculizumab (surface under the cumulative ranking area (SUCRA) &gt, 0.6) and ravulizumab (SUCRA &ge, 0.7) were similar in terms of their protective effect on hemolysis in paroxysmal nocturnal hemoglobinuria (PNH), thrombotic microangiopathy (TMA) in atypical hemolytic uremic syndrome (aHUS), and acute kidney injury (AKI) in aHUS, in comparison to pre-/off-treatment state and/or placebo (SUCRA &lt, 0.01), and eculizumab was efficacious on thrombotic events in PNH (odds ratio (OR)/95% confidence interval (95% CI) in CT and real-life NRSI, 0.07/0.03 to 0.19, 0.24/0.17 to 0.33) and chronic kidney disease (CKD) occurrence/progression in PNH (0.31/0.10 to 0.97, 0.66/0.44 to 0.98). In addition, meta-analysis on clinical trials shows that eculizumab mitigates a refractory generalized myasthenia gravis (rgMG) crisis (0.29/0.13 to 0.61) and prevents new acute antibody-mediated rejection (AMR) episodes in kidney transplant recipients (0.25/0.13 to 0.49). The update of findings from this meta-analysis will be useful to promote a better use of complement inhibitors, and to achieve personalization of treatments with this class of drugs.

Background: Interleukin-1 (IL-1)&beta, and IL-1 receptor antagonist (IL-1Ra) have been proposed as important mediators during chronic liver diseases. We aimed to determine whether the modulation of IL-1&beta, signaling with IL-1Ra impacts on liver fibrosis. Methods: We assessed the effects of IL-1&beta, on human hepatic stellate cells (HSC) and in mouse models of liver fibrosis induced by bile duct ligation (BDL) or carbon tetrachloride treatment (CCl-4). Results: Human HSCs treated with IL-1&beta, had increased IL-1&beta, IL-1Ra, and MMP-9 expressions in vitro. HSCs treated with IL-1&beta, had reduced &alpha, smooth muscle actin expression. These effects were all prevented by IL-1Ra treatment. In the BDL model, liver fibrosis and Kuppfer cell numbers were increased in IL-1Ra KO mice compared to wild type mice and wild type mice treated with IL-1Ra. In contrast, after CCl-4 treatment, fibrosis, HSC and Kupffer cell numbers were decreased in IL-1Ra KO mice compared to the other groups. IL-1Ra treatment provided a modest protective effect in the BDL model and was pro-fibrotic in the CCl-4 model. Conclusions: We demonstrated bivalent effects of IL-1Ra during liver fibrosis in mice. IL-1Ra was detrimental in the CCl-4 model, whereas it was protective in the BDL model. Altogether these data suggest that blocking IL-1-mediated inflammation may be beneficial only in selective liver fibrotic disease.

Regulatory T cells (Tregs) are a subset of T cells dedicated to suppressing immune responses to ensure immune self tolerance. Treg therapy offers the opportunity to treat transplant rejection and autoimmunity without the toxicity associated with immunosuppressive regimens. Conferring antigen specificity to Tregs using a chimeric antigen receptor (CAR) dramatically expands what targets can be pursued using Treg therapies. However, the consequences of CAR-mediated signaling for human Treg biology remain poorly understood. To address this, we generated anti-CD19 CAR Tregs with a tandem CD28-TCRζ intracellular domain. Upon in vitro co-incubation with CD19-expressing cells, CAR Tregs upregulated activation markers, proliferated, secreted IL-10, and suppressed T cell proliferation, while maintaining high FOXP3 expression and a demethylated TSDR. In humanized mice harboring CD19+ tumor cells, CAR Tregs suppressed CAR T cell proliferation. Strikingly, CAR Tregs also suppressed tumor growth, even in the absence of CAR T cells. This phenomenon was observed across three tumor cell types (B-cell leukemia, myeloid leukemia, and epithelial carcinoma) and two routes of delivery (intravenous and subcutaneous). Real-time monitoring of tumor cell survival and proliferation in vitro confirmed that CAR Tregs suppress tumor cell growth. Interestingly, single-cell cytokine analysis revealed that CAR-mediated activation of Tregs leads to higher production of IFN-γ, TNF-α, perforin, and granzyme B than anti-CD3/28 stimulation. CRISPR/Cas9-mediated ablation of granzyme B in CAR Tregs diminished their antitumor activity in vivo. These results demonstrate that CAR Treg cytotoxicity is an important concern for safe clinical translation.

The microbiological safety of islet preparations is paramount. Preservation medium contamination is frequent, and its impact on islet yield and function remains unclear. Microbiological samples collected during islet isolations from 2006 to 2016 were analyzed and correlated to isolation and allo- and autotransplantation outcomes. Microbial contamination of preservation medium was found in 64.4% of processed donor pancreases (291/452). We identified 464 microorganisms including Staphylococcus (253/464, 54.5%), Streptococcus (31/464, 6.7%), and Candida species (25/464, 5.4%). Microbial contamination was associated with longer warm and cold ischemia times and lower numbers of postpurification islet equivalents, purity, transplant rate, and stimulation index (all P < 0.05). Six percent of the preparations accepted for transplantation showed microbial contamination after isolation (12/200); 9 of 12 were Candida species. Six patients were transplanted with a sample with late microbial growth discovered after the infusion. Insulin independence rate was not affected. This risk of transplanting a contaminated islets preparation was reduced by half following the implementation of an additional sampling after 24 h of islet culture. Pancreas preservation fluid microbial contamination is associated with lower transplant rate and poorer in vitro function, but not with changes in graft survival. Culture medium testing 1 day after isolation reduces the risk of incidental transplantation with contaminated islets.

Chronic active antibody-mediated rejection (caAMR) is a major cause of allograft loss after kidney transplantation (1). The BANFF 2013 classification redefined caAMR by the presence of donor-specific anti-HLA antibodies (DSA) together with immuno-histopathological evidence for active vascular lesions of the endothelium (C4d deposits, glomerulitis, peritubular capillaritis) as well as evidence of chronic tissue injury (transplant glomerulopathy, peritubular capillary basement membrane multilayering or arterial intimal fibrosis) (2,3). Humoral immunity, detected by the presence of DSA, and B cells are considered pivotal in the development of caAMR. Gosset et al. showed that circulating DSA are responsible for accelerated allograft fibrosis independently of acute AMR (1). This article is protected by copyright. All rights reserved.

The field of xenotransplantation has fluctuated between great optimism and doubts over the last 50 years. The initial clinical attempts were extremely ambitious but faced technical and ethical issues that prompted the research community to go back to preclinical studies. Important players left the field due to perceived xenozoonotic risks and the lack of progress in pig-to-non-human-primate transplant models. Initial apparently unsurmountable issues appear now to be possible to overcome due to progress of genetic engineering, allowing the generation of multiple-xenoantigen knockout pigs that express human transgenes and the genome-wide inactivation of porcine endogenous retroviruses. These important steps forward were made possible by new genome editing technologies, such as CRISPR/Cas9, allowing researchers to precisely remove or insert genes anywhere in the genome. An additional emerging perspective is the possibility of growing humanized organs in pigs using blastocyst complementation. This article summarizes the current advances in xenotransplantation research in non-human primates and it describes the newly developed genome editing technology tools and interspecific organ generation. This article is protected by copyright. All rights reserved.

Background TAFRO syndrome has been reported in Japan among human herpesvirus 8 (HHV-8)-negative/idiopathic multicentric Castleman’s disease (iMCD) patients. To date, the majority of iMCD patients with TAFRO syndrome originate from Japan. Case presentation Herein, we report a 67-year-old HIV/HHV-8-negative Caucasian iMCD patient diagnosed with TAFRO. He presented with marked systemic inflammation, bicytopenia, terminal renal insufficiency, diffuse lymphadenopathies, and anasarca. Lymph node and bone marrow biopsies revealed atrophic germinal centers variably hyalinized and megakaryocytic hyperplasia with mild myelofibrosis. Several other biopsies performed in kidneys, liver, gastrointestinal tract, prostate, and lungs revealed unspecific chronic inflammation. The patient had a complete response to corticosteroids, tocilizumab, and rituximab. He relapsed twice following discontinuation of rituximab. When reviewing the literature, we found seven other Caucasian cases with TAFRO syndrome. There were no significant differences with those described by the Japanese cohort except for the higher frequency of kidney failure and auto-antibodies in Western patients. Conclusion This case illustrates that patients with TAFRO syndrome can develop non-specific inflammation in several tissue sites. Furthermore, this case and our review of the literature demonstrate that TAFRO syndrome can affect Caucasian and Japanese patients highlighting the importance of evaluating for this syndrome independently of ethnic background.

Replacement of pancreatic β-cells through deceased donor islet transplantation is a proven therapy for preventing recurrent life-threatening hypoglycemia in type 1 diabetes. Although near-normal glucose levels and insulin independence can be maintained for many years following successful islet transplantation, restoration of normal functional β-cell mass has remained elusive. It has recently been proposed that dedifferentiation / plasticity towards other endocrine phenotypes may play an important role in stress-induced β-cell dysfunction in type 2 diabetes. Here we report loss of end-differentiated β-cell phenotype in two intraportal islet allotransplant recipients. Despite excellent graft function and sustained insulin independence, all examined insulin-positive cells had lost expression of the end-differentiation marker, urocortin-3, or appeared to co-express the α-cell marker, glucagon. In contrast, no insulin(+) / urocortin-3(-) cells were seen in non-diabetic deceased donor control pancreatic islets. Loss of end-differentiated phenotype may facilitate β-cell survival during the stresses associated with islet isolation and culture, in addition to sustained hypoxia following engraftment. As further refinements in islet isolation and culture are made in parallel with exploration of alternative β-cell sources, graft sites and ultimately fully-vascularised bioengineered insulin-secreting microtissues, differentiation status immunostaining provides a novel tool to assess whether fully mature β-cell phenotype has been maintained. This article is protected by copyright. All rights reserved.

PURPOSE OF REVIEW Immunological barriers still preclude clinical xenotransplantation. The protective role of CD4(+)CD25(+)Foxp3(+) T regulatory cells (Treg) in allotransplantation is well described and therefore could represent a promising therapeutical tool for xenotransplantation. This review addresses the latest findings on Treg in xenotransplantation research. RECENT FINDINGS In vivo costimulation blockade based strategies including anti CD154 monoclonal antibodies (mAbs) in combination with rapamycin or anti LFA 1 mAb prolonged both concordant and discordant islets xenografts survival in a Treg dependent manner. In vitro IL 10 secretion was shown to be critical for the suppression of xenogeneic responses mediated by Treg. Moreover transgenic expression of inducible costimulator immunoglobulin or PD L1 on porcine endothelial cells inhibited human T cell proliferation in vitro and was associated with the induction of Treg and IL 10 secretion. CXCR3 mediated the recruitment of Treg to pig endothelium. Finally the recruitment of human Treg was enhanced by the immobilization of human CCL17 on pig endothelium. SUMMARY There is increasing evidence for the potential of CD4(+)CD25(+)Foxp3(+) Treg to protect xenografts. Induction of Treg in recipients and/or recruitment of human Treg to pig endothelium may represent novel strategies to prevent cell mediated rejection in pig to human xenotransplantation.

The major challenge in transplantation medicine remains long-term allograft acceptance, with preserved allograft function under minimal chronic immunosuppression. To safely achieve the goal of sustained donor-specific T and B cell non-responsiveness, research efforts are now focusing on therapies based on cell subsets with regulatory properties. In particular the transfusion of human regulatory T cells (Treg) is currently being evaluated in phase I/II clinical trials for the treatment of graft versus host disease following hematopoietic stem cell transplantation, and is also under consideration for solid organ transplantation. The purpose of this review is to recapitulate current knowledge on naturally occurring as well as induced human Treg, with emphasis on their specific phenotype, suppressive function and how these cells can be manipulated in vitro and/or in vivo for therapeutic purposes in transplantation medicine. We highlight the potential but also possible limitations of Treg-based strategies to promote long-term allograft survival. It is evident that the bench-to-beside translation of these protocols still requires further understanding of Treg biology. Nevertheless, current data already suggest that Treg therapy alone will not be sufficient and needs to be combined with other immunomodulatory approaches in order to induce allograft tolerance.

OBJECTIVE It is generally admitted that the endocrine cell organization in human islets is different from that of rodent islets. However, a clear description of human islet architecture has not yet been reported. The aim of this work was to describe our observations on the arrangement of human islet cells. RESEARCH DESIGN AND METHODS Human pancreas specimens and isolated islets were processed for histology. Sections were analyzed by fluorescence microscopy after immunostaining for islet hormones and endothelial cells. RESULTS In small human islets (40–60 μm in diameter), β-cells had a core position, α-cells had a mantle position, and vessels laid at their periphery. In bigger islets, α-cells had a similar mantle position but were found also along vessels that penetrate and branch inside the islets. As a consequence of this organization, the ratio of β-cells to α-cells was constantly higher in the core than in the mantle part of the islets, and decreased with increasing islet diameter. This core-mantle segregation of islet cells was also observed in type 2 diabetic donors but not in cultured isolated islets. Three-dimensional analysis revealed that islet cells were in fact organized into trilaminar epithelial plates, folded with different degrees of complexity and bordered by vessels on both sides. In epithelial plates, most β-cells were located in a central position but frequently showed cytoplasmic extensions between outlying non–β-cells. CONCLUSIONS Human islets have a unique architecture allowing all endocrine cells to be adjacent to blood vessels and favoring heterologous contacts between β- and α-cells, while permitting homologous contacts between β-cells.

Background Human CD4+CD25+Foxp3+ T regulatory cells (huTreg) suppress CD4+ T cell-mediated antipig xenogeneic responses in vitro and might therefore be used to induce xenograft tolerance. The present study investigated the role of the adhesion molecules, their porcine ligands, and the chemoattractant factors that may promote the recruitment of huTreg to porcine aortic endothelial cells (PAEC) and their capacity to regulate antiporcine natural killer (NK) cell responses. Methods Interactions between ex vivo expanded huTreg and PAEC were studied by static chemotaxis assays and flow-based adhesion and transmigration assays. In addition, the suppressive function of huTreg on human antiporcine NK cell responses was analyzed. Results The TNFα-activated PAEC released factors that induce huTreg chemotaxis, partially inhibited by antihuman CXCR3 blocking antibodies. Coating of PAEC with human CCL17 significantly increased the transmigration of CCR4+ huTreg under physiological shear stress. Under static conditions, transendothelial Treg migration was inhibited by blocking integrin sub-units (CD18, CD49d) on huTreg, or their respective porcine ligands intercellular adhesion molecule 2 (CD102) and vascular cell adhesion molecule 1 (CD106). Finally, huTreg partially suppressed xenogeneic human NK cell adhesion, NK cytotoxicity and degranulation (CD107 expression) against PAEC; however, this inhibition was modest, and there was no significant change in the production of IFNγ. Conclusions Recruitment of huTreg to porcine endothelium depends on particular chemokine receptors (CXCR3, CCR4) and integrins (CD18 and CD49d) and was increased by CCL17 coating. These results will help to develop new strategies to enhance the recruitment of host huTreg to xenogeneic grafts to regulate cell-mediated xenograft rejection including NK cell responses.

Depuis ces dernieres annees, il existe un interet croissant au sein de la communaute scientifique concernant les phenomenes de l’epigenetique.