Cancer immunoediting, the process by which the immune system controls tumour outgrowth and shapes tumour immunogenicity, is comprised of three phases: elimination, equilibrium and escape. Although ...many immune components that participate in this process are known, its underlying mechanisms remain poorly defined. A central tenet of cancer immunoediting is that T-cell recognition of tumour antigens drives the immunological destruction or sculpting of a developing cancer. However, our current understanding of tumour antigens comes largely from analyses of cancers that develop in immunocompetent hosts and thus may have already been edited. Little is known about the antigens expressed in nascent tumour cells, whether they are sufficient to induce protective antitumour immune responses or whether their expression is modulated by the immune system. Here, using massively parallel sequencing, we characterize expressed mutations in highly immunogenic methylcholanthrene-induced sarcomas derived from immunodeficient Rag2(-/-) mice that phenotypically resemble nascent primary tumour cells. Using class I prediction algorithms, we identify mutant spectrin-β2 as a potential rejection antigen of the d42m1 sarcoma and validate this prediction by conventional antigen expression cloning and detection. We also demonstrate that cancer immunoediting of d42m1 occurs via a T-cell-dependent immunoselection process that promotes outgrowth of pre-existing tumour cell clones lacking highly antigenic mutant spectrin-β2 and other potential strong antigens. These results demonstrate that the strong immunogenicity of an unedited tumour can be ascribed to expression of highly antigenic mutant proteins and show that outgrowth of tumour cells that lack these strong antigens via a T-cell-dependent immunoselection process represents one mechanism of cancer immunoediting.
Porcine cells devoid of three major carbohydrate xenoantigens, αGal, Neu5GC, and SDa (TKO) exhibit markedly reduced binding of human natural antibodies. Therefore, it is anticipated that TKO pigs ...will be better donors for human xenotransplantation. However, previous studies on TKO pigs using old world monkeys (OWMs) have been disappointing because of higher anti‐TKO pig antibodies in OWMs than humans. Here, we show that long‐term survival of renal xenografts from TKO pigs that express additional human transgenes (hTGs) can be achieved in cynomolgus monkeys. Kidney xenografts from TKO‐hTG pigs were transplanted into eight cynomolgus recipients without pre‐screening for low anti‐pig antibody titers. Two recipients of TKO‐hTG xenografts with low expression of human complement regulatory proteins (CRPs) (TKO‐A) survived for 2 and 61 days, whereas six recipients of TKO‐hTG xenografts with high CRP expression (TKO‐B) survived for 15, 20, 71, 135, 265, and 316 days. Prolonged CD4+T cell depletion and low anti‐pig antibody titers, which were previously reported important for long‐term survival of αGal knock‐out (GTKO) xenografts, were not always required for long‐term survival of TKO‐hTG renal xenografts. This study indicates that OWMs such as cynomolgus monkeys can be used as a relevant model for clinical application of xenotransplantation using TKO pigs.
The authors achieve long‐term survival in cynomolgus monkeys of porcine kidney xenografts devoid of three major carbohydrate xenoantigens with multiple human transgenes without pre‐screening for low anti‐pig antibody titers and prolonged T cell depletion.
Clinical islet transplantation has relied almost exclusively on intraportal administration of pancreatic islets, as it has been the only consistent approach to achieve robust graft function in human ...recipients. However, this approach suffers from significant loss of islet mass from a potent immediate blood‐mediated inflammatory response (IBMIR) and a hypoxic environment. To avoid these negative aspects of the portal site, we explored an alternative approach in which allogeneic islets were transplanted into the intrapleural space of a non‐human primate (NHP), treated with an immunosuppression regimen previously reported to secure routine survival and tolerance to allogeneic islets in NHP. Robust glycemic control and graft survival were achieved for the planned study period of >90 days. Our observations suggest the intrapleural space provides an attractive locale for islet transplantation due to its higher oxygen tension, ability to accommodate large transplant tissue volumes, and a lack of IBMIR‐mediated islet damage. Our preliminary results reveal the promise of the intrapleural space as an alternative site for clinical islet transplantation in the treatment of type 1 diabetes.
The intrapleural space supports allogeneic islet survival in a diabetic non‐human primate and thus, may represent an alternative site for clinical islet transplantation.
Gun violence results in approximately 40,000 deaths in the United States each year, yet physicians rarely discuss gun access and firearm safety with patients. Lack of education about how to have ...these conversations is an important barrier, particularly among trainees.
A 2-part training curriculum was developed for first-year residents. It included (1) a didactic presentation outlining a framework to understand types of firearm-related violence, describing institutional resources, and reviewing strategies for approaching discussions about firearms with patients; and (2) interactive case scenarios, adjusted for clinical disciplines, with standardized patients. Before and after the training, participants completed surveys on the training's relevance, efficacy, and benefit. Standardized patients provided real-time feedback to participants and completed assessments based on prespecified learning objectives.
In June-August, 2019, 148 first-year residents in Internal Medicine (n = 74), General Surgery (n = 12), Emergency Medicine (n = 15), Pediatrics (n = 22), Psychiatry (n = 16), and OB/GYN (n = 9) completed the training. Most (70%, n = 104) reported having no prior exposure to gun violence prevention education. Knowledge about available resources increased among participants from 3% (n = 5) pretraining to 96% (n = 143) posttraining. Awareness about relevant laws, such as Extreme Risk Protection Orders, and their appropriate use increased from 3% (n = 4) pretraining to 98% (n = 145) posttraining. Comfort discussing access to guns and gun safety with patients increased from a median of 5 pretraining to 8 posttraining (on a scale of 1-10 with higher scores indicating more comfort).
Delivery of a case-based gun violence prevention training program was effective and feasible in a single institution. Next steps include expanding the training to other learners (across undergraduate and graduate medical education) and institutions as well as assessing how the program changes practice over time.
Human islet transplantation has proven to be a highly effective treatment for patients with labile type 1 diabetes mellitus, which can free patients from daily glucose monitoring and insulin ...injections. However, the shortage of islet donors limits its' broad application. Porcine islet xenotransplantation presents a solution to the donor shortage and recent advances in genetic modification and immunosuppressive regimens provide renewed enthusiasm for the potential of this treatment.
Advances in genetic editing technology are leading to multigene modified porcine islet donors with alterations in expression of known xenoantigens, modifications of their complement and coagulation systems, and modifications to gain improved immunological compatibility. Recent NHP-based trials of costimulation blockade using CD154 blockade show promising improvements in islet survival, whereas results targeting CD40 are less consistent. Furthermore, trials using IL-6 receptor antagonism have yet to demonstrate improvement in glucose control and suffer from poor graft revascularization.
This review will detail the current status of islet xenotransplantation as a potential treatment for type I diabetes mellitus, focusing on recent advances in porcine xenogeneic islet production, assessment in nonhuman primate preclinical models, the outcome of human clinical trials and review barriers to translation of xenoislets to the clinic.
Through multiple mechanisms, regulatory B cells (Breg) have been shown to play an important role in the development of allograft tolerance. However, a careful understanding of the role of ...antigen‐specificity in Breg‐mediated allograft tolerance has remained elusive. In experimental models of islet and cardiac transplantation, it has been established that Bregs can be induced in vivo by anti‐CD45RB ± anti‐TIM1antibody treatment, resulting in prolonged, Breg‐dependent allograft tolerance. The importance of Breg antigen recognition has been suggested but not confirmed through adoptive transfer experiments, using tolerant WT C57BL/6 animals challenged with either BALB/c or C3H grafts. However, the importance of receptor‐specificity has not been formally tested. Here, we utilize the novel ovalbumin‐specific B cell receptor transnuclear (OBI) mice in multiple primary tolerance and adoptive transfer experiments to establish that Breg‐dependent allograft tolerance relies on antigen recognition by B cells. Additionally, we identify that this Breg‐dependent tolerance relies on the function of transforming growth factor‐β. Together, these experiments mark important progress toward understanding how best to improve Breg‐mediated allograft tolerance.
Regulatory B cells produce long‐term experimental transplant graft survival that requires proper recognition of the graft through the B cell receptor.
Regulatory B cells (Bregs) have shown promise as anti‐rejection therapy applied to organ transplantation. However, less is known about their effect on other B cell populations that are involved in ...chronic graft rejection. We recently uncovered that naïve B cells, stimulated by TLR ligand agonists, converted into B cells with regulatory properties (Bregs‐TLR) that prevented allograft rejection. Here, we examine the granular phenotype and regulatory properties of Breg‐TLR cells suppressing B cells. Cocultures of Bregs‐TLR with LPS‐activated B cells showed a dose‐dependent suppression of targeted B cell proliferation. Adoptive transfers of Bregs‐TLR induced a decline in antibody responses to antigenically disparate skin grafts. The role of Breg BCR specificity in regulation was assessed using B cell‐deficient mice replenished with transgenic BCR (OB1) and TCR (OT‐II) lymphocytes of matching antigenic specificity. Results indicated that proliferation of OB1 B cells, mediated through help from CD4+ OT‐II cells, was suppressed by OB1 Bregs of similar specificity. Transcriptomic analyses indicated that Bregs‐TLR suppression is associated with a block in targeted B cell differentiation controlled by PRDM1 (Blimp1). This work uncovered the regulatory properties of a new brand of Breg cells and provided mechanistic insights into potential applications of Breg therapy in transplantation.
Ex vivo generated regulatory B cells impede target B cell activities via a block in their differentiation.
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