Full Mismatch Research Articles

Naked Antibody-Based Conditioning Targeting CD47 and CD117 Plus Janus Kinase Inhibition Enables Toxin-Free, Radiation-Free, and Chemotherapy-Free Fully Mismatched Allogeneic Hematopoietic Stem Cell Transplantation

INTRODUCTION: Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a potentially curative therapy for numerous malignant and non-malignant hematologic diseases. To enable engraftment of donor hematopoietic stem cells (HSCs), recipients undergo conditioning with chemotherapy and irradiation to make marrow space for incoming donor HSCs and suppress host immune responses that may lead to graft rejection. These cytotoxic conditioning regimens carry risks of severe toxicities which prevents many patients from accessing the lifesaving benefit of allo-HSCT. Previously, we developed fully ablative CD45- and cKit-targeted antibody-drug conjugates (ADC) which, when combined with Janus kinase 1/2 (JAK1/2) inhibitors, enabled fully mismatched allo-HSCT with full donor chimerism and minimal toxicity while providing durable antileukemia activity (Persaud et al (2022), ASH Abstract). However, even ADCs carry potential risks of acute and chronic toxicities that may preclude their common use as HSCT conditioning agents. Moreover, unlike malignant diseases, allo-HSCT for non-malignant diseases does not require the conditioning regimen to provide antitumor benefit and partial donor chimerism may be sufficient for cure, strongly favoring the use of less intense conditioning strategies with the fewest possible toxicities. We hypothesized that naked antibody-based conditioning strategies can achieve the therapeutic benefits of allo-HSCT for non-malignant hematologic diseases, obviating exposure to toxic ADC payloads. METHODS: We combined unconjugated antibodies targeting CD47 and cKit with JAK1/2 inhibition to perform minor histocompatibility antigen (miHA)-mismatched (129/Sv→B6-Ly5.1) and fully mismatched (BALB/c→B6) murine allo-HSCT. In some full mismatch HSCT experiments, recipients included B6-gp91phox -/- mice, which serve as a model of chronic granulomatous disease (CGD) due to their deficiency in a catalytic subunit of NADPH oxidase. Mice received 100 µg anti-CD47 (clone mIAP410; BioXcell) 8 days before HSCT (d-8) as a priming dose to reduce the severity of CD47 blockade-induced anemia. Next, mice received 500 µg anti-cKit (clone ACK2; BioLegend) on d-6 and daily 500 µg doses of anti-CD47 from d-6 through d-2. For JAK1/2 inhibition, mice received oral ruxolitinib (Incyte; 2 mg drug/g chow) starting d-3 or d-1 and continuing until d+28. On d0, recipients were transplanted with 20 x 10 6 whole bone marrow cells from 129/Sv (miHA) or BALB/c (fully mismatched) mice. Peripheral blood donor chimerism was followed monthly by flow cytometry for CD45.2 + (miHA) or H-2D d+ (fully mismatched) cells. Oxidative burst among granulocytes in B6-gp91phox -/- recipients was assessed by dihydrorhodamine 123 (DHR123) staining after phorbol 12-myristate 13-acetate (PMA) stimulation. RESULTS: CD47 and cKit antibodies plus ruxolitinib enabled multilineage engraftment in both miHA and fully mismatched allo-HSCT, including myeloid lineage donor chimerism of 95-99% (Figure 1A). As expected, CD47 blockade induced significant but transient morbidity from anemia during the peritransplant period; notably, a shorter duration of ruxolitinib treatment before HSCT (starting d-1 instead of d-3) improved the tolerability of the regimen without impacting engraftment success. Allo-HSCT of B6-gp91phox -/- mice led to near complete replacement of host granulocytes in peripheral blood with donor granulocytes, whose DHR123 positivity upon PMA stimulation indicated an intact oxidative burst capacity (Figure 1B). CONCLUSIONS: Combination of antibodies targeting CD47 and cKit with JAK1/2 inhibition provides a novel conditioning strategy for allo-HSCT in mouse models, achieving high-level, stable multilineage engraftment without radiation, chemotherapy, or exposure to toxic ADC payloads. The near complete donor chimerism among granulocytes made it particularly well suited to correcting phagocyte oxidase function in the gp91phox -/- model of CGD. Future studies seek to 1) mitigate the peritransplant anemia caused by CD47 blockade using Fc-silenced anti-CD47 reagents, 2) determine the proportions of donor- versus recipient-derived myeloid cells in non-hematopoietic tissues of allo-HSCT recipients, and 3) use murine infection models to evaluate the impact of allo-HSCT on host defense in transplanted B6-gp91phox -/- recipients.

Novel T cell/organoid culture system allows ex vivo modeling of intestinal graft-versus-host disease.

Acute graft-versus-host disease (GvHD) remains the biggest clinical challenge and prognosis-determining complication after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Donor T cells are acceptedly key mediators of alloreactivity against host tissues and here especially the gut. In support of previous studies, we found that the intestinal intra-epithelial lymphocyte (IEL) compartment was dynamically regulated in the course of MHC class I full mismatch allo-HSCT. However, while intestinal epithelial cell (IEC) damage endangers the integrity of the intestinal barrier and is a core signature of intestinal GvHD, the question whether and to what degree IELs are contributing to IEC dysregulation is poorly understood. To study lymphoepithelial interaction, we employed a novel ex vivo T cell/organoid co-culture model system. Here, allogeneic intra-epithelial T cells were superior in inducing IEC death compared to syngeneic IEL and allogeneic non-IEL T cells. The ability to induce IEC death was predominately confined to TCRβ+ T cells and was executed in a largely IFNγ-dependent manner. Alloreactivity required a diverse T cell receptor (TCR) repertoire since IELs genetically modified to express a TCR restricted to a single, non-endogenous antigen failed to mediate IEC pathology. Interestingly, minor histocompatibility antigen (miHA) mismatch was sufficient to elicit IEL-driven IEC damage. Finally, advanced live cell imaging analyses uncovered that alloreactive IELs patrolled smaller areas within intestinal organoids compared to syngeneic controls, indicating their unique migratory properties within allogeneic IECs. Together, we provide here experimental evidence for the utility of a co-culture system to model the cellular and molecular characteristics of the crosstalk between IELs and IEC in an allogeneic setting ex vivo. In the light of the emerging concept of dysregulated immune-epithelial homeostasis as a core aspect of intestinal GvHD, this approach represents a novel experimental system to e.g. screen therapeutic strategies for their potential to normalize T cell/IEC- interaction. Hence, analyses in pre-clinical in vivo allo-HSCT model systems may be restricted to hereby positively selected, promising approaches.

Minding the manner: attention to motion events in Turkish–Dutch early bilinguals

AbstractLanguages differ in the way motion events are encoded. In satellite-framed languages, motion verbs typically encode manner, while in verb-framed languages, path. We investigated the ways in which satellite-framed Dutch and verb-framed Turkish co-determine one’s attention to motion events in early bilinguals. In an EEG oddball paradigm, Turkish–Dutch bilinguals (n = 25) and Dutch controls (n = 27) watched short video clips of motion events, followed by a still picture that matched the preceding video in four ways (oddball design: 10% full match, 10% manner match, 10% endpoint match, and 70% full mismatch). We found that both groups showed similar oddball P300 effects, associated with task-related attention. Group differences were revealed in a late positivity (LP): The endpoint-match elicited a larger LP than the manner-match in the bilinguals, which may reflect language-driven attention. Our results indicate that cross-linguistic manner encoding difference impacts attention at a later stage.

Tolerance of a Vascularized Composite Allograft Achieved in MHC Class-I-mismatch Swine via Mixed Chimerism.

BackgroundVascularized composite allografts (VCAs) allow reconstruction of devastating injuries and amputations, yet require lifelong immunosuppression that is associated with significant morbidity. Induction of immune tolerance of VCAs would permit widespread use of these procedures. VCAs are acquired from deceased donors most likely to be fully-MHC-mismatched (in contrast to living-related renal transplant donor-recipient pairs matched at one MHC haplotype). After achieving VCA tolerance in a swine model equivalent to clinical living-related renal transplants (single-haplotype MHC mismatches: e.g., “mother-daughter”/haploidentical), we tested our protocol in MHC class I, class II, and fully-MHC-mismatched pairs. Although class II mismatched swine demonstrated similar results as the haploidentical scenario (stable mixed chimerism and tolerance), our protocol failed to prevent rejection of class I and full mismatch VCAs. Here, we describe a new adapted conditioning protocol that successfully achieved tolerance across MHC class-I-mismatch barriers in swine.MethodsSwine were treated with non-myeloablative total body and thymic irradiation two days prior to infusion of bone marrow cells from an MHC class I-mismatched donor. They also received a short-term treatment with CTLA4-Ig (Belatacept®) and anti-IL6R mAb (Tociluzimab®) and were transplanted with an osteomyocutaneous VCA from the same donor.ResultsStable mixed chimerism and tolerance of MHC class-I-mismatched VCAs was achieved in 3 recipients. Allograft tolerance was associated with a sustained lack of anti-donor T cell response and a concomitant expansion of double negative CD4-CD8- T cells producing IL-10.ConclusionsThis study demonstrates the first successful mixed chimerism-induced VCA tolerance in a large animal model across a MHC class-I-mismatch. Future studies aimed at fully-mismatched donor-recipient pairs are under investigation with this protocol.

Tissue Engineering Scaffolds for Minimally-Invasive Immunosurveillance of Acute Cellular Graft Rejection

<h3>Purpose</h3> As there is no assay to predict the risk of acute cellular allograft rejection (ACAR), clinicians rely on protocol graft biopsy and aggressive, <i>one-size-fits-all</i> immunosuppression. Immunosuppression protects grafts from ACAR but increases systemic toxicities. Endomyocardial biopsy (EMB) histology suffers from variability and lags behind molecular biomarkers. <b>A minimally invasive surveillance method is urgently needed to quantify early risk of rejection for minimizing graft biopsy and personalizing treatment.</b> <h3>Methods</h3> Biomaterial scaffolds accumulate immune cells producing biomarkers of ACAR as an engineered immunological niche. We implanted subcutaneous poly-caprolactone scaffolds in murine heart or skin transplants to determine if they could identify ACAR. Rag2KO mice received full MHC mismatch allografts or syngeneic controls, and ACAR was initiated as a tunable event by C57BL/6 T cell transfer. Scaffolds were explanted and analyzed via histology and differential gene expression by RNA sequencing. <h3>Results</h3> The scaffolds provided a novel measure of graft health. We algorithmically identified <b>11 differentially-expressed genes as biomarkers</b> that distinguish mice with rejecting grafts from those with healthy grafts. <i>Importantly, the scoring system detects oncoming ACAR prior to clinical signs of rejection.</i> Also, histology of these niches identified changes associated with ACAR progression. <h3>Conclusion</h3> Gene expression in the cell-capture scaffold identified a biomarker signature of early ACAR, without invasive biopsy. <b>Scaffold cell capture technology provides a leading indicator of ACAR by monitoring tissue-specific immune responses associated with allograft rejection.</b> This implantable scaffold enables minimally invasive histological evaluation and molecular calculation of the early risk of rejection to reduce the frequency of routine EMB and personalize immune suppression that ultimately could prolong transplant life while minimizing risk.

The discrepancy between admission and discharge diagnoses: Underlying factors and potential clinical outcomes in a low socioeconomic country.

ObjectiveThe discrepancy between admission and discharge diagnosis can lead to possible adverse patient outcomes. There are gaps in integrated studies, and less is understood about its characteristics and effects. Therefore, this study was conducted to determine the frequency, characteristics, and outcomes of diagnostic discrepancies at admission and discharge.Design and data sourcesThis retrospective study reviewed the admitting and discharge diagnoses of adult patients admitted at Aga Khan University Hospital (AKUH), Internal Medicine Department between October 2018 and February 2019. The frequency and outcomes of discrepancies in patient diagnoses were noted among Emergency Department (ED) physician versus admitting physician, admitting physician versus discharge physician, and ED physician versus discharge physician for the full match, partial match, and mismatch diagnoses. The studied outcomes included interdepartmental transfer, Intensive Care Unit (ICU) transfer, in-hospital mortality, readmission within 30 days, and the length of stay. For simplicity, we only analyzed the factors for the discrepancy among ED physicians and discharge physicians.ResultsOut of 537 admissions, there were 25.3–27.2% admissions with full match diagnoses while 18.6–19.4% and 45.3–47.9% had mismatch and partial match diagnoses respectively. The discrepancy resulted in an increased number of interdepartmental transfers (5–5.8%), ICU transfers (5.6–8.7%), in-hospital mortality (8–11%), and readmissions within 30 days in ED (14.4%-16.7%). A statistically significant difference was observed for the ward’s length of stay with the most prolonged stay in partially matched diagnoses (6.3 ± 5.4 days). Among all the factors that were evaluated for the diagnostic discrepancy, older age, multi-morbidities, level of trainee clerking the patient, review by ED faculty, incomplete history, and delay in investigations at ED were associated with significant discrepant diagnoses.ConclusionsDiagnostic discrepancies are a relevant and significant healthcare problem. Fixed patient or physician characteristics do not readily predict diagnostic discrepancies. To reduce the diagnostic discrepancy, emphasis should be given to good history taking and thorough physical examination. Patients with older age and multi-morbidity should receive significant consideration.

242 - Targeted CD45 Antibody Drug Conjugate Enables Full Mismatch Allogeneic Hematopoietic Stem Cell Transplantation in a Murine HSCT Model As a Single Agent

242 - Targeted CD45 Antibody Drug Conjugate Enables Full Mismatch Allogeneic Hematopoietic Stem Cell Transplantation in a Murine HSCT Model As a Single Agent

Single Agent CD45-Targeted Antibody Drug Conjugate Enables Full Mismatch Allogeneic Hematopoietic Stem Cell Transplantation in a Murine HSCT Model

Introduction Allogeneic hematopoietic stem cell transplant (Allo-HSCT) is a potentially curative treatment for malignant and non-malignant blood disorders. However, current conditioning regimens limit the use of this curative procedure in many eligible patients due to regimen-related mortality and morbidities, including organ toxicity, infertility, and secondary malignancies. We are developing novel antibody drug conjugates (ADC) as conditioning agents that can achieve full myeloablation as a single agent that may reduce toxicity associated with current conditioning regimens. We have generated an anti-murine ADC targeting CD45 and assessed its effectiveness as single agent conditioning regimen in a fully allogeneic murine HSCT model. Methods Our tool CD45 ADC is engineered for rapid clearance (t1/2=1.7hr) to enable HSCT after conditioning. A single dose of 3 mg/kg is fully myeloablative in C57BL/6 mice. To determine if the tool CD45-ADC could successfully condition recipients for fully mismatched allo-HSCT, we evaluated the ability of a single dose of 5 mg/kg of the tool CD45-ADC to condition C57BL/6 hosts (H-2b, CD45.2+) for transplant with cells from CByJ.SJL(B6) donors (H-2d, CD45.1+). A matched dose of an isotype ADC (Iso-ADC) was used as a negative control, while 9 Gy TBI was used as a conventional conditioning positive control. Conditioned mice were transplanted with 4x107 whole BM cells, and peripheral blood chimerism was assessed over 22 weeks. At 22 weeks, donor hematopoietic cell chimerism was evaluated in the spleen, bone marrow, and thymus of recipients. Results In the fully mismatched Balb/c → C57Bl/6 allo-HSCT model, conditioning with a single dose of 5 mg/kg of CD45-ADC as a single agent was well tolerated and enabled full allogeneic donor chimerism (n=2 separate experiments). Peripheral blood chimerism was observed in mice conditioned with CD45-ADC at week 4 and maintained through week 22 (Figure 1). Multilineage reconstitution was observed in the T-, B-, and myeloid cell compartments with &amp;gt;90% donor chimerism seen in each compartment, indicative of HSC engraftment. These results were comparable to chimerism seen in the 9 Gy TBI positive control. Treatment with a non-targeting isotype ADC at a matched dose was not effective (Figure 1). For all groups, stem cell chimerism in the bone marrow matched that in the periphery. Splenic and thymic donor immune cell reconstitution was similar between CD45-ADC and TBI conditioning at week 22 (Figure 1), demonstrating that CD45-ADC efficiently depletes host lymphocytes in secondary lymphoid organs while preserving the capacity of the host thymus to support de novo generation of donor-derived T cells after transplantation. Conclusion Conditioning with CD45-ADC was well-tolerated, fully myeloablative, and enabled complete chimerism in a full mismatch allo-HSCT model as a single agent. This targeted, readily translatable approach for safer conditioning could improve the risk-benefit profile for allogenic and haploidentical HSCT and may extend the curative potential of HSCT to more patients suffering from blood cancers and other diseases that may benefit from HSCT. Disclosures Hyzy: Magenta Therapeutics: Current Employment, Current equity holder in publicly-traded company. Proctor:Magenta Therapeutics: Current Employment. Gillard:Magenta Therapeutics: Current Employment. Hammond:Magenta Therapeutics: Current Employment, Current equity holder in publicly-traded company. Sarma:Magenta Therapeutics: Ended employment in the past 24 months. Clark:Magenta Therapeutics: Current Employment. Bhat:Magenta Therapeutics: Current Employment. Lamothe:Magenta Therapeutics: Current Employment. Palchaudhuri:Magenta Therapeutics: Current Employment. Pearse:Magenta Therapeutics: Ended employment in the past 24 months. McDonagh:Magenta Therapeutics: Ended employment in the past 24 months. Kiem:Magenta Therapeutics: Consultancy; CSL: Consultancy; Homology Medicines: Membership on an entity's Board of Directors or advisory committees; Rocket Pharma: Membership on an entity's Board of Directors or advisory committees; Umoja: Membership on an entity's Board of Directors or advisory committees; Enochian: Membership on an entity's Board of Directors or advisory committees; Vor Biopharma: Membership on an entity's Board of Directors or advisory committees. Wagner:Rocket Pharmaceuticals, Inc.: Consultancy, Current equity holder in publicly-traded company; Novartis: Research Funding; Magenta Therapeutics: Consultancy, Research Funding; BlueRock: Research Funding; Gadeta: Membership on an entity's Board of Directors or advisory committees. Blazar:Magenta Therapeutics: Consultancy; Fate Therapeutics Inc.: Research Funding; BlueRock Therapeutics: Research Funding; Childrens' Cancer Research Fund: Research Funding; KidsFirst Fund: Research Funding; Tmunity: Other: Co-founder; BlueRock Therapeuetic: Consultancy. Boitano:Magenta Therapeutics: Ended employment in the past 24 months, Patents &amp; Royalties. Cooke:Magenta Therapeutics: Ended employment in the past 24 months, Patents &amp; Royalties. Davis:Magenta Therapeutics: Current Employment, Current equity holder in publicly-traded company.

Hukou System, Horizontal, Vertical, and Full Job-Education Mismatch and Wage Progression among College Floating Population in Beijing, China

This article investigates college graduates in Beijing, China, and asks, First: Whether college graduates without local hukou are prone to educational mismatch? Second: What role does the hukou system play in the educational mismatch? And third: Whether college graduates without local hukou are willing to lower their wages in order to get a hukou? I use the Beijing College Students Panel Survey (BCSPS), and multinomial logit models and the linear regression analyses are conducted. I find that college graduates with (without) local hukou through job are more likely to be vertical and full mismatch than locals, and those who obtain a hukou through job have a higher full mismatch. After considering the educational mismatch, there is no significant difference in monthly wages between college graduates (not) having a hukou by work and locals.

Superior inhibition of alloantibody responses with selective CD28 blockade is CTLA-4 dependent and T follicular helper cell specific.

Anti-donor antibodies cause immunologic injury in transplantation. CD28 blockade with CTLA-4-Ig has the ability to reduce the incidence of these donor-specific antibodies (DSA), but its mechanism is suboptimal for the inhibition of alloimmunity in that CTLA-4-Ig blocks both CD28 costimulation and CTLA-4 coinhibition. Thus selective CD28 blockade that spares CTLA-4 has potential to result in improved inhibition of humoral alloimmunity. To test this possibility, we utilized a full allogeneic mismatch murine transplant model and T follicular helper (Tfh):B cell co-culture system. We observed that selective blockade with an anti-CD28 domain antibody (dAb) compared to CTLA-4-Ig led to superior inhibition of Tfh cell, germinal center, and DSA responses in vivo and better control of B cell responses in vitro. CTLA-4 blockade enhanced the humoral alloresponse and, in combination with anti-CD28 dAb, abrogated the effects of selective blockade. This CTLA-4-dependent inhibition was Tfh cell specific in that CTLA-4 expression by Tfh cells was necessary and sufficient for the improved humoral inhibition observed with selective CD28 blockade. As CD28 blockade attracts interest for control of alloantibodies in the clinic, these data support selective CD28 blockade as a superior strategy to address DSA via the sparing of CTLA-4 and more potent targeting of Tfh cells.

IgA Nephropathy Recurrence after Kidney Transplantation: Role of Recipient Age and Human Leukocyte Antigen-B Mismatch

Background: Recurrence of immunoglobulin (Ig)A nephropathy (rIgAN) is a growing cause of kidney allograft dysfunction. This study was aimed at investigating factors associated with rIgAN and the subsequent progression to end-stage renal disease (ESRD). Methods: Retrospective study including consecutive patients with IgA nephropathy (IgAN) who received a kidney transplant in our center between 1992 and 2016 and had a renal biopsy by clinical indication. The date of detection of chronic kidney disease (CKD) 5 was used as renal outcome. Results: Eighty-six kidney transplants were performed in patients with IgAN, 38 (44%) were from living donors (related n = 26). rIgAN was diagnosed in 23 allografts (27%). Renal function and proteinuria at the end of the follow-up period were worst in the rIgAN patients compared to those without rIgAN (2.2 vs. 1.4 mg/dL, p = 0.014, and 1.16 vs. 0.49 g/day, p = 0.005, respectively). Risk of rIgAN and progression to CKD 5 decreased with patient’s age (hazard ratio [HR] 0.95, 95% CI 0.92–0.98, p = 0.002, and HR 0.97, 95% CI 0.83–0.97, p = 0.008 per year, respectively). Patients with rIgAN had a higher risk of progression to CKD 5 (HR 6.7, 95% CI 1.3–35.7, p = 0.025). Full donor-recipient mismatch in the human leukocyte antigen (HLA)-B loci decreased the risk of rIgAN (HR 0.22, 95% CI 0.06–0.76, p = 0.017). Conclusions: rIgAN was an independent risk factor for ESRD after renal allograft. Younger age increased the risk of rIgAN and CKD 5. Conversely, HLA-B mismatching was a potential protective factor for rIgAN of this glomerular disease.

Successful Allogeneic Hematopoietic Stem Cell Transplantation in Mice Mediated By Well-Tolerated Conditioning Regimens Based on CD45-Targeted Antibody Drug Conjugate: Implications for Haplo Transplantation

<h3>Introduction</h3> Allogeneic hematopoietic stem cell transplant (Allo-HSCT) is a potentially curative treatment for malignant and non-malignant blood disorders. However, current conditioning regimens limit its use due to regimen-related mortality and morbidities. We are developing novel antibody drug conjugates (ADCs) to provide the benefit of full-intensity conditioning to remove disease-causing cells while reducing the severity of treatment-related adverse events. These ADCs are designed to deliver agents specifically to CD45+ target cells as a sole conditioning agent or as the primary conditioning agent in a reduced intensity conditioning protocol for allo-HSCT. The aim of this study was to model this approach with a tool anti-mouse CD45 ADC to determine if targeted ADCs can be used to enable allo-HSCT in mice. <h3>Methods</h3> We developed a tool anti-mouse CD45 ADC engineered to have a short half-life (T_1/2 = 1.7hr) to enable HSCT. The optimal dose of tool CD45-ADC was established in a congenic autologous mouse transplant model. Next, the tool CD45-ADC was evaluated alone or in combination with low dose (0.5 Gy) total body irradiation (TBI) or T cell-depleting anti-mouse antibodies (CD4 and CD8, 0.25 mg/kg IP) in a full mismatch allo-HSCT model (Balb/c donors (H-2d, CD45.1+) into C57Bl/6 recipients (H-2b, CD45.2+)). 9 Gy TBI served as the conventional conditioning positive control. Conditioned mice were transplanted with 2 × 10⁷ whole bone marrow cells, and peripheral blood chimerism assessed over 16 weeks. <h3>Results</h3> A single 3 mg/kg dose of the tool CD45-ADC was an effective regimen in a congenic autologous mouse transplant model, resulting in full donor chimerism comparable to conditioning with 9 Gy TBI. In a full mismatch allo-HSCT model, a single dose of CD45-ADC enabled mixed myeloid chimerism out to 3 weeks as a single agent, but the chimerism was transient. In combination with low dose TBI or T cell depleting antibodies, the tool CD45-ADC enabled >90% peripheral donor chimerism by week 4 post-transplantation, which was maintained through week 16. Multilineage reconstitution of T-, B-, and myeloid cell compartments was observed (>90% donor chimerism) and was comparable to chimerism seen in the 9 Gy TBI positive control. Treatment with a non-targeting isotype ADC was not effective (Figure 1A, 1B). <h3>Conclusion</h3> A single dose of the tool CD45-ADC is fully myeloablative and enables complete chimerism in a full mismatch allo-HSCT model with low dose TBI or supplemental T cell depletion. Future experiments will examine the use of tool CD45-ADC conditioning in HSCT as a treatment in mouse autoimmune disease models. This targeted, readily translatable approach for safer conditioning could improve the risk-benefit profile for allogenic and haploidentical HSCT and may extend the curative potential of this therapeutic modality.

Abstract 113: Type-1 Interferons Impair The Immunoregulatory Activity Of IL-10: Understanding The Mechanisms Of Abrogation Of Transplant Tolerance

PURPOSE: Induction of long term transplant survival by “costimulation blockade” (CoB) regimens is impaired by inflammatory responses. In particular, multiple studies reported that engagement of toll like receptors (TLR) abrogate the tolerogenic effect of CoB. Despite the identification of type-1 interferons (TI-IFN) as mediators of this effect in multiple models, their target population and specific pathway used remain undefined. To better understand how TI-IFN could interfere with the induction of transplant tolerance, we studied their impact on the immunomodulatory properties of IL-10. METHODS: Full mismatch skin transplants were performed using dorsal skin from Balb/c into C57BL/6 mice and animals received a peri-transplant regimen based on DST (107 T-depleted splenocytes; on day 0) and anti-CD154 mAb (MR-1; on day 0, 7, 14) +/- anti-IL-10R (on day 0, 7, 14). Mouse T cells were isolated by negative-selection and Tmem and Treg subsets identified by flow cytometry. IL-10R expression and phospho-STAT3 induction after IL-10 or IL-6 stimulation in T cells were measured via flow cytometry. The gene expression profile of T cell subsets exposed to TI-IFN was assessed by microarray and quantitative PCR analysis. Protein levels were measured by Western Blot. RESULTS: Our result showed that IL-10 has a fundamental role in the protective effect of CoB (transplant survival: MST 105d with CoB vs 47d with anti-IL-10R administration). We then studied the impact of T cell exposure to TI-IFN on IL-10 signaling. Following 48h of in vitro incubation with IFN-β, memory T cells (Tmem) and Tregs presented a dramatic defect in the production of phospho-STAT3 in response to IL-10. This effect was very selective, as IL-6 signaling (post IFN-β exposure) induced normal levels of phospho-STAT3. The reduced accumulation of phospho-STAT3 in conditioned cells resulted in the inhibition of the upregulation of mRNAs for LIGHT, Sphk1 and Tarm-1 - three genes we have discovered are induced by IL-10 in T cells. Encouragingly, this effect was slowly reversible with removal of TI-IFN, suggesting a “druggable” pathway. Microarray and flow cytometry data indicated that this IL-10-specific unresponsiveness was not associated with any reduction of IL-10 receptor expression or an increase in SOCS (Suppressor of Cytokine Signaling) 1 and 3, nor with reduced STAT3 cytoplasmic availability. Instead, this analysis suggested a novel role for the transcription factor STAT1 in dampening IL-10 signaling. Using T cells from STAT1-KO mice, we show that the absence of STAT1 prevented IL-10 inhibition induced by IFN-β in Treg and Tmem, supporting our new model. CONCLUSION:Overall, these results highlight the importance of IL-10 in the therapeutic effect of CoB regimens and reveal a new molecular mechanism whereby TI-IFN interfere with IL-10 signaling, and ultimately with regulation of alloreactivity. Identifying a strategy to target this mechanism could provide a valuable aid in the clinical efficacy of CoB-based immunomodulatory strategies.

GDF15 Regulates Malat-1 Circular RNA and Inactivates NFκB Signaling Leading to Immune Tolerogenic DCs for Preventing Alloimmune Rejection in Heart Transplantation.

Recombinant human growth differentiation factor 15 (rhGDF15) affects dendritic cell (DC) maturation. However, whether GDF15 is expressed in DCs and its roles and signaling in DCs remain largely unknown. It is unclear whether GDF15-DCs can induce immune tolerance in heart transplantation (HT). This study aims to understand the impact of endogenous GDF15 on DC's development, function, underlying molecular mechanism including circular RNA (circRNA). This study will also explore GDF15-DC-mediated immune modulation in HT. Bone marrow (BM) derived DCs were cultured and treated to up- or down regulate GDF15 expression. Phenotype and function of DCs were detected. Expression of genes and circRNAs was determined by qRT-PCR. The signaling pathways activated by GDF15 were examined. The impact of GDF15 treated DCs on preventing allograft immune rejection was assessed in a MHC full mismatch mouse HT model. Our results showed that GDF15 was expressed in DCs. Knockout of GDF15 promoted DC maturation, enhanced immune responsive functions, up-regulated malat-1 circular RNA (circ_Malat 1), and activated the nuclear factor kappa B (NFκB) pathway. Overexpression of GDF15 in DCs increased immunosuppressive/inhibitory molecules, enhanced DCs to induce T cell exhaustion, and promoted Treg generation through IDO signaling. GDF15 utilized transforming growth factor (TGF) β receptors I and II, not GFAL. Administration of GDF15 treated DCs prevented allograft rejection and induced immune tolerance in transplantation. In conclusion, GDF15 induces tolerogenic DCs (Tol-DCs) through inhibition of circ_Malat-1 and the NFκB signaling pathway and up-regulation of IDO. GDF15-DCs can prevent alloimmune rejection in HT.

MRI Profile and Collateral Status in Patients with a Transient Ischemic Attack and an Intracranial Artery Occlusion.

Transient ischemic attack may rarely reveal an intracranial artery occlusion. We analyzed acute magnetic resonance imaging (MRI) patterns and early outcome after reperfusion therapy in these cases. Clinical and imaging data were taken retrospectively from our comprehensive stroke center registry. Two MRI patterns were determined. Pattern A: full mismatch with negative diffusion-weighted imaging (DWI) and perfusion defect. Pattern B: large mismatch with positive DWI and perfusion defect. MRI-derived collateral flow maps were automatically generated from the raw of dynamic susceptibility contrast MRI. Patients were treated either by recombinant tissue plasminogen activator (rtPA) alone or in combination with mechanical thrombectomy. From October 1, 2010 to May 15, 2016, 1,019 patients were admitted and treated by t-PA within 4.5 hours of stroke onset of them; 14 had a transient ischemic attack (TIA) within the 6 hours preceding MRI. Perfusion imaging was performed in 11 patients. An arterial occlusion was found in all of them, 11 patients had a distal anterior circulation occlusion, whereas 3 patients (21%) had a proximal occlusion. According to MRI, 6 patients showed pattern A, whereas 5 patients had pattern B. Good collaterals were observed in 10 patients (6 patients with grade 3 and 4 patients with grade 4), whereas 1 patient had poor collaterals (grade 2). The day 1 National Institutes of Health Stroke Scale median was 0. Modified Rankin Scale median at 3 months was 0. TIAs may reveal acute intracranial artery occlusion. Acute MRI may able to assist in therapeutic decision.

Type-1 Interferons Impair the Immunoregulatory Activity of IL-10

A growing body of evidence shows that induction of long term transplant survival by “costimulation blockade” (CoB) regimens is impaired by inflammatory responses. In particular, multiple studies reported that engagement of toll like receptors (TLR) abrogate the tolerogenic effect of CoB. Despite the identification of type-1 interferons (TI-IFN) as mediators of this effect in multiple models, the target population and specific pathway used by TI-IFN to induce this effect, remain unknown. CoB therapies rely on the enhancement of the frequency and suppressive activity of regulatory T cells (Tregs) that use interleukin 10 (IL-10) as a key weapon of suppression. IL-10 is a pleiotropic and immunomodulatory cytokine that in the field of transplant tolerance, despite its anticipated protective function, maintains a controversial role. To better understand how an inflammatory environment, more specifically IFN-β, could interfere with the induction of transplant tolerance, we studied its impact on the immunomodulatory properties of IL-10. Our results showed that the transient blockade of IL-10 signaling had a deleterious impact on the ability of a CoB regimen based on the infusion of donor specific transfusion (DST) and anti-CD154 (MR-1), to prolong the survival of murine full mismatch skin transplants (MST 105d vs 47d with anti-IL-10R administration). Following 48h of in vitro incubation with IFN-β, memory T cells (Tmem) and Tregs presented a dramatic defect in the production of phospho-STAT3 in response to IL-10. This effect was very selective, as IL-6 signaling (post IFN-β exposure) induced normal levels of phospho-STAT3. The reduced accumulation of phospho-STAT3 in conditioned cells resulted in the inhibition of the upregulation of mRNAs for LIGHT, Sphk1 and Tarm-1 – three genes we have discovered are induced by IL-10 in T cells. Encouragingly, this inhibition of IL-10 signaling is slowly reversible with the removal of TI-IFN. Microarray and flow cytometry data indicated that this IL-10-specific unresponsiveness was not associated with any reduction of IL-10 receptor expression or an increase in SOCS (Suppressor of Cytokine Signaling) 1 and 3, nor with reduced STAT3 cytoplasmic availability. Instead, this analysis suggested a novel role for the transcription factor STAT1 in dampening IL-10 signaling. Using T cells from STAT1-KO mice, we show that the absence of STAT1 prevented IL-10 inhibition induced by IFN-β in Treg and Tmem, supporting our new model. Overall, these results highlight the importance of IL-10 signaling in the therapeutic effect of CoB regimens in transplantation. More importantly, they reveal a new molecular mechanism whereby IFN-β interferes with IL-10 signaling, its suppressive function in T cells, and ultimately with regulation of alloreactivity. Identifying a strategy to target this mechanism will be a powerful tool to improve the efficacy of immunomodulatory strategies for transplant tolerance induction. AAI 2016-2017 Careers in Immunology Fellowship. JDRF strategic research agreement 2-SRA-2016-310-S-B.

Brain Gain or Brain Waste? Horizontal, Vertical, and Full Job-Education Mismatch and Wage Progression among Skilled Immigrant Men in Canada

This study examines the incidence and wage effects of vertical, horizontal, and full job-education mismatch for high skilled immigrant and native-born men over a six-year period, using a Canadian longitudinal dataset. Immigrants (particularly racial minorities immigrants) are more likely to be fully mismatched than white native-born Canadians. Full mismatch lowers initial wages, especially for racial minority immigrants. Full mismatch accelerates immigrants' wage growth slightly over time, but this is not enough to narrow the immigrant wage gap over the six-year survey period. The results highlight the importance of disaggregating the different types of job-education mismatch experienced by immigrants.

Type-1 interferon impairs the immunoregulatory activity of IL-10: Understanding the mechanisms of abrogation of transplant tolerance

Abstract Long term transplant survival by costimulation blockade (CoB)-based regimens is impaired or eroded by inflammatory responses. Type-1 interferons (TI-IFN) are key mediators of this effect, however, their target population and mechanism of action remain unknown. To better understand how IFN-β interferes with the induction of transplant tolerance, we studied its impact on the recently discovered immunomodulatory properties of interleukin 10 (IL-10) in mouse T cells. We first demonstrate that IL-10 has an unappreciated fundamental role in transplant tolerance, as its transient blockade in recipients of full mismatch skin grafts impairs the efficacy of a peri-transplant CoB regimen based on donor specific transfusion (DST) plus anti-CD154. Moreover, when T cells are exposed to IFN-β in vitro, they develop a selective dramatic defect in their response to IL-10 (but not to IL-6) both at the signaling and gene-induction level. This IL-10-specific unresponsiveness is not associated with any reduction of IL-10R expression or an increase in SOCS1 and 3, nor with a reduced STAT3 cytoplasmic availability. Instead, our gene-expression and functional analysis suggests a novel “cross-regulatory” role for the transcription factor STAT1. Encouragingly, this inhibition is slowly reversible with the removal of TI-IFN, proving the feasibility a pharmacological intervention. Overall, these results reveal a new molecular mechanism whereby IFN-β interferes with the suppressive function of IL-10 in T cells, and potentially with regulation of alloreactivity. Identifying a strategy to target this mechanism will then be a powerful tool to improve the efficacy of CoB-based strategies for transplant tolerance induction.

Guanine oxidation signal enhancement in DNA via a polyacrylonitrile nanofiber-coated and cyclic voltammetry-treated pencil graphite electrode

This study investigated the electrochemical detection of specific nucleic acid hybridization sequences using a nanofiber-coated pencil graphite biosensor. The biosensor was developed to detect Val66Met single point mutations in the brain-derived neurotrophic factor gene, which is frequently observed in neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, and bipolar disorder. The oxidation signal of the most electroactive and stable DNA base, i.e., guanine, was used at approximately +1.0 V. Pencil graphite electrode (PGE) surfaces were coated with polyacrylonitrile nanofibers by electrospinning. Cyclic voltammetry was applied to the nanofiber-coated PGE to pretreat its surfaces. The application of cyclic voltammetry to the nanofiber-coated PGE surfaces before attaching the probe yielded a four fold increase in the oxidation signal for guanine compared with that using the untreated and uncoated PGE surface. The signal reductions were 70% for hybridization, 10% for non-complementary binding, and 14% for a single mismatch compared with the probe. The differences in full match, non-complementary, and mismatch binding indicated that the biosensor selectively detected the target, and that it was possible to determine hybridization in about 65 min. The detection limit was 0.19 μg/ml at a target concentration of 10 ppm.

Complete B Cell Deficiency Reduces Allograft Inflammation and Intragraft Macrophages in a Rat Kidney Transplant Model.

Increasingly, it is being appreciated that B cells have broad roles beyond the humoral response and are able to contribute to and regulate inflammation. The specific role of B cells in the pathogenesis of early allograft inflammation remains unclear. To address this question, we generated B cell-deficient (B) Lewis rats via clustered regularly interspaced short palindromic repeats (CRISPR) technology. In a full mismatch transplant model, kidneys from Brown Norway donors were transplanted into B Lewis recipients or wild type Lewis recipients. T cell-mediated rejection was attenuated with cyclosporine. Renal inflammation was reduced at 1 week after transplant (Banff scores for interstitial inflammation, microvascular inflammation, glomerulitis, and C4d) in allografts from B recipients. The reduction in interstitial inflammation was predominantly due to a decline in graft infiltrating macrophages. Intragraft T-cell numbers remained unchanged. In addition, B-cell deficiency was associated with increased T regulatory cells and reduced splenic T follicular helper cells at baseline; and significantly increased intragraft and splenic IL-10 mRNA levels after transplant. In vitro, B and wild type splenic T cells produced similar levels of IFN-γ in response to T cell-specific activation. B-cell deficiency in this model produced an anti-inflammatory phenotype with a shift toward regulatory T-cell populations, production of anti-inflammatory cytokines (IL-10), and a reduction in allograft inflammation. These findings define a role for B cells to influence the cell populations and mediators involved in the pathogenesis of early allograft inflammation.