One-way Mixed Lymphocyte Reaction Research Articles

Restore Veto Property in Low Dose Aspirin/ASA Treated Preeclampsia Placenta Mesenchymal Stem Cells: Insights Into ASA-mediated Clinical Response*

Preeclampsia (PE) is a pregnancy complication characterized by elevated blood pressure, proteinuria, and other laboratory abnormalities. PE affects 2–8% of pregnancies globally and can lead to preterm birth and other complications for the mother and fetus. Successful pregnancy depends on the ability of the mother’s immune system to tolerate the allogeneic fetus. However, in PE, this immune tolerance is exacerbated by inflammation. Transforming growth factor β (TGF-β) is important to retain an immune balance in healthy pregnancy. In PE, TGF-β level is reduced, with an imbalance of the T-cell subset pool to favor inflammation. Omics studies by our group reported an increase in TGF-β signaling when PE-derived placenta mesenchymal stem cells (P-MSCs) were treated with low dose aspirin (ASA). This correlated with increased cycling quiescence and epigenetic changes, resembling healthy P-MSCs. This study tested the hypothesis that ASA could restore the veto property of P-MSCs to mitigate inflammation. ASA (10 mM) treated P-MSCs from PE and healthy placentas increased TGFβ1 and its receptor. The ASA treated MSCs, when added as third-party cells to a one-way mixed lymphocyte reaction, suppressed T-cell proliferation. Prediction studies with omics data indicated that ASA-mediated TGFβ signaling could explain ASA-induced blunting of cell apoptosis. Together, the findings support ASA-mediated expression of TGFβ1 and its receptor on P-MSCs from PE to restore the ability to be licensed as immune suppressor to mitigate PE inflammation. The findings provide new insight into the benefit of ASA treatment for PE.

Combination of oral STING agonist MSA-2 and anti-TGF-β/PD-L1 bispecific antibody YM101: a novel immune cocktail therapy for non-inflamed tumors

BackgroundNon-inflamed tumors, including immune-excluded and immune-desert tumors, are commonly resistant to anti-PD-1/PD-L1 (α-PD-1/PD-L1) therapy. Our previous study reported the potent antitumor activity of anti-TGF-β/PD-L1 bispecific antibody YM101 in immune-excluded tumors. However, YM101 had limited antitumor activity in immune-desert models. MSA-2 is a novel oral stimulator of interferon genes (STING) agonist, which activates the innate immune system and may synergize with YM101 in overcoming immunotherapy resistance.MethodsThe dose-dependent effect of MSA-2 on STING signaling was determined by interferon-β level. The maturation and function of dendritic cell (DC) were measured by flow cytometry, RNA-seq, one-way mixed lymphocyte reaction (MLR), OVA peptide pulse, and cytokine/chemokine detection. The synergistic effect between MSA-2 and YM101 was assessed by one-way MLR. The macrophage activation was measured by flow cytometry and cytokine/chemokine detection. The in vivo antitumor activity of MSA-2 combined with YM101 was explored in syngeneic murine tumor models. After treatments, the alterations in the tumor microenvironment (TME) were detected by flow cytometry, immunohistochemistry staining, immunofluorescence staining, RNA-seq, and single-cell RNA-seq (scRNA-seq).ResultsMSA-2 could promote the maturation and antigen presentation capability of murine DC. In the one-way MLR assay, MSA-2 synergized with YM101 in enhancing naive T cell activation. Moreover, MSA-2 stimulated the classical activation of macrophage, without significant influence on alternative activation. Further in vivo explorations showed that MSA-2 increased multiple proinflammatory cytokines and chemokines in the TME. MSA-2 combined with YM101 remarkedly retarded tumor growth in immune-excluded and immune-desert models, with superior antitumor activity to monotherapies. Flow cytometry, bulk RNA-seq, and scRNA-seq assays indicated that the combination therapy simultaneously boosted the innate and adaptive immunity, promoted antigen presentation, improved T cell migration and chemotaxis, and upregulated the numbers and activities of tumor-infiltrating lymphocytes.ConclusionOur results demonstrate that MSA-2 synergizes with YM101 in boosting antitumor immunity. This immune cocktail therapy effectively overcomes immunotherapy resistance in immune-excluded and immune-desert models.

Abstract 3499: M1069 as dual A2A/A2B adenosine receptor antagonist counteracts immune-suppressive mechanisms of adenosine and reduces tumor growth in vivo

Abstract Under physiological conditions, the extracellular concentrations of adenosine are low, however, levels dramatically increase under metabolically stressful conditions, including inflammation and cancer. The regulatory functions of adenosine are mediated through four members of the adenosine receptor family: A1, A2A, A2B, and A3. While A2A was considered the major contributor to adenosine-mediated suppression of T cell, natural killer cell, and myeloid cell functions, A2B has also recently emerged as a potential modulator of these processes. Both A2A and A2B signal through the same Gs-mediated activation of adenylate cyclase, which can allow the lower affinity A2B receptor to compensate for the inhibition of A2A in an adenosine-rich tumor microenvironment (TME). A2B receptors are also reported to support tumor growth independent of A2A through the Gq subunit of G-protein-coupled receptor-mediated production of vascular endothelial growth factor (VEGF) by myeloid and tumor cells. Therefore, simultaneous targeting of both the A2A and A2B receptors may provide a higher potential for cancer immunotherapy in an adenosine-rich TME, where A2B can act in compensatory or complementary means to A2A. M1069 is a small-molecule, dual antagonist of the A2A and A2B adenosine receptors with a selectivity of >100 fold against the A1 and A3 receptors. In assays with primary human T cells, M1069 caused a dose-dependent suppression of 5′-N-ethylcarboxamide adenosine (stable analog of adenosine)-stimulated cyclic adenosine monophosphate (cAMP) and phosphorylated cAMP- response element binding protein (pCREB) induction and rescue of interleukin (IL)-2 production (A2A readout). M1069 also suppressed VEGF production from human macrophages (A2B readout) in adenosine-rich settings. M1069 exhibited superior suppression of protumorigenic cytokine secretion, including CXCL1, CXCL5 and granulocyte-colony stimulating factor, and the rescue of IL12 secretion from adenosine-differentiated dendritic cells, as compared to an A2Aselective antagonist. In addition, in a one-way mixed lymphocyte reaction assay, adenosine-differentiated dendritic cells treated with M1069 demonstrated superior T cell activation compared to adenosine-differentiated dendritic cells treated with an A2A-selective antagonist. These findings were further corroborated with the results from in vivo studies in a murine CD73hi/adenosine-rich 4T1 syngeneic breast tumor model, in which M1069, but not an A2A-selective antagonist, reduced tumor growth as a monotherapy and enhanced anti-tumor activity with chemotherapeutic agents. In summary, M1069 is a potent, dual A2A/A2B adenosine receptor antagonist, which is expected to counteract immune-suppressive mechanisms in the presence of high concentrations of adenosine and enhance the anti-tumor activity of chemotherapies. Citation Format: Rinat Zaynagetdinov, Kai Schiemann, Kalyan Nallaparaju, Natalya Belousova, Armine Matevossian, Zhouxiang Chen, Giorgio Kradjian, Meghana Pandya, Nemisha Dawra, Eva-Maria Krauel, Elissaveta Petrova, Oliver Poeschke, David Fischer, Marc Lecomte, Andree Blaukat, Bayard Huck, Jacques Moisan. M1069 as dual A2A/A2B adenosine receptor antagonist counteracts immune-suppressive mechanisms of adenosine and reduces tumor growth in vivo [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3499.

Evaluation of equine xenogeneic mixed lymphocyte reactions using 5-ethynyl-2’-deoxyuridine (EdU)

Allogeneic solid organ transplantation is currently the only treatment option for end stage organ disease. The shortage of available donor organs has driven efforts to utilize xenogeneic organs for transplantation. In vitro methods for evaluating immune-compatibility are a quick and low cost means of screening novel tissue products prior to more involved, expensive, and invasive live animal studies. Recently, a new analog of the DNA base thymidine, 5-ethynyl-2’-deoxyuridine (EdU), was developed. It may be used in a fast, efficient and specific means of evaluating cell proliferation via flow cytometry. This study was designed to test and optimize this platform for assessing equine xenogeneic one-way mixed lymphocyte reaction (MLR) to porcine stimulator cells. Furthermore, it was hypothesized that an enriched T-lymphocyte (T-cell) population would generate a stronger proliferative response to stimulation, and higher levels of cytokine production when compared to unfractionated peripheral blood mononuclear cells (PBMCs). PBMCs and T-cells were isolated from 3 horses and 4 pigs. Equine xenogeneic MLRs were set up using porcine allogeneic MLRs as a reference for clinically acceptable levels of cell proliferation. Equine T-cells showed significantly greater EdU incorporation in one-way xenogeneic MLRs than equine PBMCs. However, there was no significant difference in cell proliferation between porcine T-cell and PBMC as responders in allogenic one-way MLRs. Given the results of this study, we consider that enriched equine T-cells should be used in preference to unfractionated PBMCs when attempting to evaluate the equine xenogeneic response using the EdU assay as an indicator of suitability for transplant in vivo.

Evaluation of checkpoint inhibitor therapies using a mixed lymphocyte reaction (MLR) assay

Abstract Checkpoint inhibitors block the ‘off’ signals that are engaged when T cells interact with antigen-presenting cells, such as dendritic cells (DCs). This increases T cell activation and enhances the anti-tumor response. Here we demonstrate the use of advanced flow cytometry to evaluate these immunotherapies in vitro by co-culturing immune cells from two donors in an MLR assay. Assays were set up as either one-way or two-way MLR co-cultures. One-way assays combined isolated DCs from one donor with CD4+ T cells from another. Two-way assays mixed PBMCs from two donors. Cells and checkpoint inhibitors were plated in 96 or 384-well formats for 3–6 days. Samples taken during the time course were analyzed for cell subsets and cytokine concentrations using the iQue® Advanced Flow Cytometry Platform. Expression of activation marker CD25 on T cells was 3-fold greater after 6 days in co-culture with DCs (62 ± 2 %) compared to T cells in monoculture (22 ± 9 %). The addition of an anti-PD1 checkpoint inhibitor induced a further, concentration dependent increase in CD25 expression. This was accompanied by increased production of cytokines indicative of activation and inflammation, such as TNFα and CCL2. Throughout the study, there were large differences in sensitivity to drug response between donor pairs. For example, IFNγ release increased 13.5-fold upon addition of anti-CTLA4 (17 ng/mL) with one donor pair, compared to only 1.3-fold with another. This highlights the need to characterize drug activity using multiple immune cell donor pairs. These data exemplify the use of advanced flow cytometry to generate pharmacological data for checkpoint inhibitor activity on T cells in MLR, with the potential to profile libraries of novel therapeutics in minimal time.

Identification of alpha-enolase as a potential immunogenic molecule during allogeneic transplantation of human adipose-derived mesenchymal stromal cells

Background aimsGiven their low immunogenicity, immunoregulatory effects and multiple differentiation capacity, mesenchymal stromal cells (MSCs) have the potential to be used for “off-the-shelf” cell therapy to treat various diseases. However, the allorejection of MSCs indicates that they are not fully immune-privileged. In this study, the authors investigated the immunogenicity of human adipose-derived MSCs (Ad-MSCs) and identified potential immunogenic molecules. MethodsTo evaluate the immunogenicity of human Ad-MSCs in vivo, cells were transplanted into humanized mice (hu-mice), then T-cell infiltration and clearance of human Ad-MSCs were observed by immunofluorescence and bioluminescence imaging. One-way mixed lymphocyte reaction and flow cytometry were performed to evaluate the immunogenicity of human Ad-MSCs in vitro. High-throughput T-cell receptor (TCR) repertoire sequencing and mass spectrometry were applied to identified potential immunogenic molecules. ResultsThe authors observed that allogeneic Ad-MSCs recruited human T cells and caused faster clearance in hu-mice than non-humanized NOD.Cg-Prkdcscid IL2rgtm1Wjl/SzJ (NSG) mice. The proliferation and activation of T cells were significantly enhanced during in vitro co-culture with human Ad-MSCs. In addition, the level of HLA-II expression on human Ad-MSCs was dramatically increased after co-culture with human peripheral blood mononuclear cells (PBMCs). High-throughput sequencing was applied to analyze the TCR repertoire of the Ad-MSC-recruited T cells to identify dominant TCR CDR3 sequences. Using synthesized TCR CDR3 peptides, the authors identified several potential immunogenic candidates, including alpha-enolase (ENO1). The ENO1 expression level of Ad-MSCs significantly increased after co-culture with PBMCs, whereas ENO1 inhibitor (ENOblock) treatment decreased the expression level of ENO1 and Ad-MSC-induced proliferation of T cells. ConclusionsThe authors’ findings improve the understanding of the immunogenicity of human Ad-MSCs and provide a theoretical basis for the safe clinical application of allogeneic MSC therapy.

P.161: Small Molecule Inhibitor of Toll-like Receptor-4, TAK-242, Attenuates Allogenic Immune Responses In Vitro

Introduction: Development of innate and adaptive immune response against transplanted islets has a major impact on the poor long term survival of allogenic islet transplants. Our previous studies have shown that TAK-242, a small molecule inhibitor of toll-like receptor-4 either in a soluble form or covalently linked to the islet surface can effectively protect islets from damage inflicted by sterile inflammation in vitro and also prolongs survival of syngeneic islet transplants. Based on recent reports indicating crosstalk between TLR-4 and major histocompatibility complex molecules, we hypothesized that TAK-242 can inhibit proliferation of lymphocytes in response to allogenic stimulation. Methods: Human peripheral blood mononuclear cells labeled with carboxyfluorescein succinimidyl ester were tested for proliferation in a one-way mixed lymphocyte reaction against mitomycin treated, CellTrace Violet-labeled allogenic splenocytes as stimulators. Proliferation of CD4+ and CD8+ T cells was analyzed by flow cytometry. Concentrations of pro-inflammatory cykokines in the culture supernatant was measured by Luminex Multiplex Bead Assay. Varying concentrations (0–30 µM) of TAK242 or MAP84, an inactive structure analog of TAK242, were added to the culture medium. Results: Addition of TAK-242 to the mixed lymphocyte reaction dose dependently inhibited proliferation of both CD4+ and CD8+ T cells (Fig. 1A). The inhibition of proliferation was optimal on day 5. Proliferation of CD4+ and CD8+ T cells was not affected by the addition of MAP84 at similar concentrations. Cytokine measurements showed that IL-2 concentrations were not inhibited by TAK-242. However, proinflammatory cytokines IL-1beta, IL-6, IP-10 and TNF-alpha were significantly inhibited specifically by TAK-242 (Fig. 1B). These results mirrored our previous data showing TAK-242 inhibition of pro-inflammatory cytokines by islets stimulated with TLR-4 ligands. Conclusion: The present data has shown for the first time that blockade of toll-like receptor-4 by TAK-242 is an effective method to attenuate development of T cell response against allogenic targets in addition to the inhibition of inflammation. Crosstalk between TLR pathway with other critical receptors involved the development of immune response is likely to play a role in this inhibition. Further experiments to decipher the mechanism underlying this unique immunosuppressive property of TAK-242 are in progress.

Combine and conquer: manganese synergizing anti-TGF-\u03b2/PD-L1 bispecific antibody YM101 to overcome immunotherapy resistance in non-inflamed cancers

BackgroundOur previous work showed that the anti-TGF-β/PD-L1 bispecific antibody YM101 effectively overcame anti-PD-L1 resistance in immune-excluded tumor models. However, in immune-desert models, the efficacy of YM101 was limited. Bivalent manganese (Mn2+) is identified as a natural stimulator of interferon genes (STING) agonist, which might enhance cancer antigen presentation and improve the therapeutic effect of YM101.MethodsThe effect of Mn2+ on STING pathway was validated by western blotting and enzyme-linked immunosorbent assay. Dendritic cell (DC) maturation was measured by flow cytometry. The synergistic effect between Mn2+ and YM101 in vitro was determined by one-way mixed lymphocyte reaction, CFSE dilution assay, and cytokine detection. The in vivo antitumor effect of Mn2+ plus YM101 therapy was assessed in CT26, EMT-6, H22, and B16 tumor models. Flow cytometry, RNA-seq, and immunofluorescent staining were adopted to investigate the alterations in the tumor microenvironment.ResultsMn2+ could activate STING pathway and promote the maturation of human and murine DC. The results of one-way mixed lymphocyte reaction showed that Mn2+ synergized YM101 in T cell activation. Moreover, in multiple syngeneic murine tumor models, Mn2+ plus YM101 therapy exhibited a durable antitumor effect and prolonged the survival of tumor-bearing mice. Relative to YM101 monotherapy and Mn2+ plus anti-PD-L1 therapy, Mn2+ plus YM101 treatment had a more powerful antitumor effect and a broader antitumor spectrum. Mechanistically, Mn2+ plus YM101 strategy simultaneously regulated multiple components in the antitumor immunity and drove the shift from immune-excluded or immune-desert to immune-inflamed tumors. The investigation in the TME indicated Mn2+ plus YM101 strategy activated innate and adaptive immunity, enhanced cancer antigen presentation, and upregulated the density and function of tumor-infiltrating lymphocytes. This normalized TME and reinvigorated antitumor immunity contributed to the superior antitumor effect of the combination therapy.ConclusionCombining Mn2+ with YM101 has a synergistic antitumor effect, effectively controlling tumor growth and prolonging the survival of tumor-bearing mice. This novel cocktail strategy has the potential to be a universal regimen for inflamed and non-inflamed tumors.

Abstract 1797: Preclinical characterization of Sym024, a novel anti-CD73 antibody

Abstract Tumor cells are surrounded by a complex microenvironment (the tumor microenvironment, or TME) that influences each step of tumorigenesis. In the TME, increased concentrations of immune modulating factors such as adenosine help tumor cells evade host anti-tumor immune responses. Adenosine binds to adenosine receptors (ARs) expressed on various immune cells such as CD4+ and CD8+ T cells, myeloid cells and natural killer (NK) cells. These receptors exhibit distinct properties and cell and tissue distribution. Binding of adenosine to a subset of ARs suppresses the anti-tumor responses of T cells and NK cells and augments the activity of immunosuppressive cells such as regulatory T cells and myeloid-derived suppressor cells, thus promoting tumor progression. The generation of adenosine in the TME is mediated by a group of ectonucleotidases, including CD39 and CD73, which work in a common pathway converting extracellular ATP to adenosine. CD73 is frequently overexpressed on human tumor cells and mediates the hydrolysis of AMP to adenosine, particularly under hypoxic conditions. Importantly, CD73 overexpression correlates with poorer prognosis in various cancers, including lung, gastric, head and neck, pancreatic, cholangiocarcinoma, colorectal, bladder, triple negative breast, ovarian, and kidney cancer, and melanoma. Inhibition of the enzymatic activity of CD73 therefore represents an attractive way of relieving the immune suppressive activity of adenosine in the TME.Sym024 is an Fc-attenuated human monoclonal antibody that binds to human and cynomolgus monkey CD73 with sub-nanomolar avidity. Sym024 binds to a distinct epitope on the enzyme on the opposite side relative to the catalytic center and potently inhibits the activity of soluble CD73 as well as CD73 expressed on numerous cancer cell lines and primary lymphocytes. Importantly, CD73 inhibition by Sym024 alleviates AMP-mediated inhibition of T cell proliferation and activation. In vitro one-way mixed lymphocyte reaction results demonstrate the utility of combining CD73 inhibition with PD-1 blockade, as Sym024 acts to reverse the immune suppressive effect of adenosine production, thereby allowing effective T cell activation by an anti-PD-1 antibody (Sym021). Mechanistically, Sym024 inhibits cellular CD73 by direct enzymatic inhibition with moderate shedding or degradation of CD73 in vitro. In preclinical in vivo tumor models, Sym024 effectively inhibits CD73 activity and tumor growth. Sym024 was well tolerated with no observed toxicity in repeat dose studies in monkeys at dose levels up to 100 mg/kg. Dose-proportional and linear pharmacokinetics (PK) was observed at high dose levels while nonlinear PK became evident at lower exposure levels. Sym024 is currently under clinical investigation. Citation Format: Janus S. Jakobsen, Matteo Riva, Maria C. Melander, Randi W. Hansen, Klaus Kofoed, Mikkel W. Pedersen, Jutta Deckert, Lene Hansen, Niels Jorgen Skartved, Johan Lantto, Camilla Frohlich, Michael Monrad Grandal. Preclinical characterization of Sym024, a novel anti-CD73 antibody [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1797.

Administration of Cells Engineered to Secrete Fviii-mcoET3 in Prenatal Sheep Recipients Results in Sustained Curative Fviii Plasma Levels for 3 Years after Birth, without Immune or Toxicity-Related Adverse Events

The treatment of hemophilia A (HA) patients by prenatal transplantation (PNT) is a feasible, yet underestimated and unexplored clinical approach. The procedure, similar to that of an amniocentesis, poses minimal risk to both the fetus and the mother. Herein, we report on the PNT of sheep fetuses (n=23) with human placental cells (PLC) transduced with a lentiviral vector encoding a bioengineered high-expression fVIII transgene (mcoET3), at a dose of 107-108/kg at 60-64 gestational days, which corresponds to 16-18 gestational weeks in humans. The cells secreted 5.1-9.7IU-fVIII/106 cells/24h, with a vector copy number of 0.35-0.99 per diploid genome equivalent. 9 animals were lost to natural causes unrelated to the treatment or the procedure, or were euthanized for tissue histopathology. Fourteen animals were available for long-term evaluation. Animals followed up over a 1-year (n=14), 2-year (n=9), and 3-year (n=6) period had increased mean plasma fVIII activity levels of 62.1%, 45.6%, and 50.98% respectively, demonstrating that despite the rapid growth of the animals from approximately 0.1kg at the time of PNT to an average of 80kg by year 3, the fVIII produced by the transplanted cells was sufficient to maintain steady levels throughout the duration of the study. We also examined whether PNT-treated animals developed liver inflammation and/or mounted an immune response to the transplanted cells or the fVIII produced by the mcoET3 transgene. At all-time points post-PNT, hematological parameters and liver enzymes (AST, ALT, and alkaline phosphatase) were normal, demonstrating the absence of any liver toxicity. To determine if PNT-treated animals developed a humoral response to mcoET3, an ELISA was performed at 3-6 and 10-16 months postnatally and demonstrated that PNT-treated animals were devoid of anti-mcoET3 IgG. To establish whether these animals had developed memory T cell responses to mcoET3, ELISpot assays for IFN-g (Th1) and IL-4 (Th2) were performed at 3 different time points. No mcoET3-specific Th1 or Th2 cells were ever detected in any of the PNT recipients. To determine if the PNT recipients developed an immune response to the transplanted PLC, we performed one-way mixed lymphocyte reactions (MLR) against the transplanted PLC, and used a screening panel-reactive antibody test (PRA) to identify the development of anti-HLA antibodies specific for the HLA phenotype of the transplanted PLC. MLR demonstrated robust reactivity towards third-party human lymphocytes but not to the transplanted PLC. In addition, no PLC specific anti-HLA antibodies were found, however 2 of the treated animals had detectable levels of xenogeneic antibodies, towards other HLA phenotypes. RTqPCR analysis demonstrated engraftment of transplanted PLC in all major organs and histopathologic examination showed no evidence of any lentiviral-related or procedural toxicity in any tissue examined. In conclusion, PNT of fetal sheep recipients resulted in sustained high fVIII plasma levels for more than 3 years after birth, with no evidence of therapy-related toxicity, nor the development of fVIII inhibitors. Thus, these studies attest to the feasibility, immunologic advantage, and safety of treating HA prior to birth. Disclosures Doering: Kilpatrick, Townsend & Stockton: Consultancy; Expression Therapeutics, LLC: Current equity holder in private company, Patents & Royalties, Research Funding.

Engineering Tolerance toward Allogeneic CAR-T Cells by Regulation of MHC Surface Expression with Human Herpes Virus-8 Proteins

Allogeneic, off-the-shelf (OTS) chimeric antigen receptor (CAR) cell therapies have the potential to reduce manufacturing costs and variability while providing broader accessibility to cancer patients and those with other diseases. However, host-versus-graft reactivity can limit the durability and efficacy of OTS cell therapies requiring new strategies to evade adaptive and innate-immune responses. Human herpes virus-8 (HHV8) maintains infection, in part, by evading host T and natural killer (NK) cell attack. The viral K3 gene encodes a membrane-tethered E3 ubiquitin ligase that discretely targets major histocompatibility complex (MHC) class I components, whereas K5 encodes a similar E3 ligase with broader specificity, including MHC-II and the MHC-like MHC class I polypeptide-related sequence A (MIC-A)- and sequence B (MIC-B)-activating ligands of NK cells. We created γ-retroviruses encoding K3 and/or K5 transgenes that efficiently transduce primary human Tcells. Expression of K3 or K5 resulted in dramatic downregulation of MHC-IA (human leukocyte antigen [HLA]-A, -B, and -C) and MHC class II (HLA-DR) cell-surface expression. K3 expression was sufficient for Tcells to resist exogenously loaded peptide-MHC-specific cytotoxicity, as well as recognition in one-way allogeneic mixed lymphocyte reactions. Further, in immunodeficient mice engrafted with allogeneic Tcells, K3-transduced Tcells selectively expanded invivo. Ectopic K5 expression in MHC class I-, MIC-A+/B+ K562 cells also reduced targeting by primary NK cells. Coexpression of K3 in prostate stem cell antigen (PSCA)-directed, inducible MyD88/CD40 (iMC)-enhanced CAR-T cells did not impact cytotoxicity, Tcell growth, or cytokine production against HPAC pancreatic tumor target cells, whereas K5-expressing cells showed a modest reduction in interleukin (IL)-2 production without effect on cytotoxicity. Together, these results support application of these E3 ligases to advance development of OTS CAR-T cell products.

Human iPSC-Derived Neural Crest Stem Cells Exhibit Low Immunogenicity

Recent clinical trials are evaluating induced pluripotent stem cells (iPSCs) as a cellular therapy in the field of regenerative medicine. The widespread clinical utility of iPSCs is expected to be realized using allogeneic cells that have undergone thorough safety evaluations, including assessment of their immunogenicity. IPSC-derived neural crest stem cells (NCSCs) have significant potential in regenerative medicine; however, their application in cellular therapy has not been widely studied to date, and no reports on their potential immunogenicity have been published so far. In this study, we have assessed the expression of immune-related antigens in iPSC-NCSCs, including human leukocyte antigen (HLA) class I and II and co-stimulatory molecules. To investigate functional immunogenicity, we used iPSC-NCSCs as stimulator cells in a one-way mixed lymphocyte reaction. In these experiments, iPSC-NCSCs did not stimulate detectable proliferation of CD3+ and CD3+CD8+ T cells or induce cytokine production. We show that this was not a result of any immunosuppressive features of iPSC-NCSCs, but rather more consistent with their non-immunogenic molecular phenotype. These results are encouraging for the potential future use of iPSC-NCSCs as a cellular therapy.

Preliminary study on tolerance induction by combined of rat thymus and metanephros anlages transplantation preconditioned with cyclophosphamide protocol

Objective To investigate whether allo-or xenotransplantation tolerance can be induced by transplanted thymus combined with metanephros primordia, from rats to cyclophosphamide (CP) pretreated recipients. Methods Two pairs of thymus and metanephros primordia were extracted from the Lewis rats on embryonic day16 (E16) and implanted into experiment (Ⅰ) group or control (Ⅱ, Ⅲ, Ⅳ) group renal capsules and omenta of thymectomized recipients, which had been pretreated with CP (80 mg/kg in BN rats and 200 mg/kg in C57BL/6 mice, ip, q6d×4). Post-transplantation, subcutaneous injection (sc, qd×12 d) of cyclosporine [8 mg/(kg·d) in BN rat and 12 mg/(kg·d) in C57BL/6 mouse] were simultaneously administrated till the 13th day. Histopathological examination of thymus and metanephros grafts and functional of developed metanephroi were performed post-transplantation. Rat seruminterleukin (IL)-2 and interferon-γ (IFN-γ) levels, one-way mixed lymphocyte reaction (MLR) and skin transplantation tests were measured. Results On the 14th day post-xenotransplantation, the thymus and metanephros primordia of Lewis rats were not found in the C57BL/6 mouse. On the 21st day after allotransplantation, the thymus and metanephros of some experimental (Ⅰ) group developed well, displaying partial urinary function. In experimental (Ⅰ) group, Banff rejection score (χ2=6.316, P 0.05) and SI had no significant difference (F=0.920, P>0.05). 5-7 weeks post-transplantation, acute rejection of metanephros and thymus deteriorated and connective tissue scars gradually formed. Conclusion Using the CP pretreatment protocol, E16 Lewis thymus and metanephros anlagens xenografted into C57BL/6 mice failed to grow and function, whereas fail to induce allogeneic immune tolerance but can grow and develop in the peritoneal cavity of BN rat, produce donor-specific immune hyporesponsiveness. Key words: Embryo; Thymus Primordia; Metanephros primordia; Transplantation; Tolerance

Indoleamine 2,3-dioxygenase suppresses humoral alloimmunity via pathways that different to those associated with its effects on T cells.

Chronic antibody-mediated rejection remains a major cause of late graft loss. Regarding cellular alloimmunity, the immunosuppressive properties of indoleamine 2,3-dioxygenase (IDO) have been well investigated; however, little is known of its effects on humoral alloimmunity. Therefore, the present study aimed to evaluate the effects of IDO on humoral alloimmunity. We developed a method for the induction of humoral alloimmunity in a one-way mixed lymphocyte reaction (MLR), which was measured with an antibody-mediated complement-dependent cytotoxicity assay using resting cells, which are similar to the stimulator cells of the aforementioned MLR. In parallel, cellular alloimmunity was assessed in two-way MLRs. The IDO inhibitor 1-methyl-DL-tryptophan was used for evaluating the role of IDO. In order to investigate whether the pathways known to serve a role in the effects of IDO on T cells are applied in humoral alloimmunity, the general control nonderepressible-2 (GCN-2) kinase activator tryptophanol and the aryl hydrocarbon receptor (AhR) inhibitor CH223191 were employed. The IDO inhibitor was revealed to increased cellular autoimmunity, but was decreased by the GCN-2 kinase activator. Unexpectedly, the AhR inhibitor decreased cellular alloimmunity. In addition, the IDO inhibitor was observed to suppress humoral alloimmunity, which may occur in manners independent of GCN-2 kinase AhR. The present study proposed that IDO may decrease humoral alloimmunity in primary human peripheral blood mononuclear cells via pathways that differ to those associated with its effect on T cells.

Differentiation of adult human retinal pigment epithelial cells into dopaminergic-like cells in vitro and in the recipient monkey brain

BackgroundCell therapy is proposed to be a potential treatment for Parkinson’s disease (PD). Although fetal retinal pigment epithelial (RPE) cells have been tested in trials for treating PD patients, controversy has been raised over the issue of whether such cells can be reprogrammed into dopamine-producing cells for therapeutic efficacy. Here, we aim to investigate whether adult human RPE cells can be reprogrammed into dopamine-producing cells both in vitro and in the recipient monkey brain.MethodsThe RPE layer was isolated from frozen posterior eyeball tissue after penetrating keratoplasty surgery. The tumorigenicity of RPE cells was examined by G-banding and a tumor formation assay in nude mice. Immunogenicity was measured using a one-way mixed lymphocyte reaction (MLR) assay. Dopamine-production in chemically reprogrammed RPE cells was measured by HPLC. Finally, RPE cells were grafted into the brains of monkeys with MPTP-induced PD in order to investigate the potential of such cells treating PD patients in the future.ResultsRPE cell lines have been successively established from adult human eye tissues. Such cells can be chemically reprogrammed into dopamine-producing cells in vitro. Moreover, after being grafted into the brain caudate putamen of monkeys with MPTP-induced PD, RPE cells became tyrosine hydroxylase-positive cells, and recipient PD monkeys showed significant improvement of clinical conditions.ConclusionsThis preclinical study using a primate model indicates that human adult RPE cells could be a potential cell source for the treatment of PD in the future.

Assessment of Humoral Alloimmunity in Mixed Lymphocyte Reaction.

Humoral alloimmunity remains a significant and unresolved problem that constrains allograft survival. Thus, there is a need for the development of an easy, preferably non-radioactive, and inexpensive protocol for assessing the effect of various drug treatments on humoral alloimmunity. In order to satisfy this demand, we developed such a protocol in which de novo alloantibodies production is induced in one-way mixed lymphocyte reaction (MLR). The amount and capacity of the generated alloantibodies in the supernatant of each one-way MLR is assessed using an antibody-mediated cell dependent cytotoxicity (CDC) assay. The principle of the assay relies on the assessment of cellular survival of resting PBMCs isolated from the same donors, supplemented with the alloantibodies from the one-way MLR supernatant. The lesser is the cellular survival, the higher the production of alloantibodies in one-way MLR and consequently the more potent the humoral alloimmunity.

Uric acid increases cellular and humoral alloimmunity in primary human peripheral blood mononuclear cells.

Hyperuricaemia is common among kidney transplant recipients and has been associated with worse graft outcome. Since episodes of acute cellular rejection and chronic humoral rejection contribute to decreased graft survival, in this study the effect of uric acid on cellular and humoral alloimmunity was evaluated. Cellular alloimmunity was assessed by cell proliferation in two-way mixed lymphocyte reaction (MLR) with human peripheral blood mononuclear cells (PBMC). For assessing humoral alloimmunity we developed a method in which humoral alloimmunity was induced in one-way MLR. Then the de novo production of alloantibodies was measured with an antibody-mediated complement-dependent cytotoxicity assay, in which supernatants from the above MRLs were used against resting PBMC similar to the stimulator cells of the above MLRs. Uric acid at a concentration above its crystallization threshold increased cellular proliferation in two-way MLRs. Supernatants from one-way MLRs performed in the presence of uric acid were more cytotoxic against PBMC from individuals that had conferred the stimulator cells for the above MLRs. Uric acid increases both cellular and humoral alloimmunity in human PBMC. These results offer a possible pathogenetic mechanism for the observed relation between hyperuricaemia and worse kidney allograft survival.

Immune Tolerance Induced by Decitabine Combined With Multiple Allogeneic Bone Marrow Mononuclear Cell Infusion

ObjectiveThe aim of our study was to investigate the strategy of immune tolerance induced by the demethylating drug decitabine (DAC) combined with multiple allogeneic bone marrow mononuclear cell (BMMNC) infusions. MethodsAn animal model with C57BL/6 mice as recipients and a BALB/c mouse as the donor was established. C57BL/6 mice were randomly divided into the following groups: DAC, BMMNC, DAC+BMMNC, and the control groups. Mice in the DAC and DAC+BMMNC groups were given DAC (5 μg/kg) on days 1, 2, 7, 8, 13, and 14. On experimental days 3, 9, and 15, BMMNCs (5 × 106/mouse/time) from BALB/c mice were infused into mice of the BMMNC and DAC+BMMNC groups. One-way mixed lymphocyte reaction (MLR), interleukin-2 reverse test, and in vitro adoptive transfer experiments were performed. The ratio of regulatory T cells in splenocytes, chimera detection, and median survival time of skin grafts were recorded. ResultsMLR showed that the stimulation index of the DAC+BMMNC group was significantly lower compared with the other 3 groups (P < .01), but still showed a strong proliferative response to the third-party unrelated donor KM mice, with no significant difference compared with the other 3 groups. The MLR low reactivity of the DAC+BMMNC group could be reversed by exogenous interleukin-2. After adding an equal amount of splenocytes from a C57BL/6 mouse in the DAC+BMMNC group, MLR of control group significantly decreased (P < .05). Flow cytometry showed the ratio of regulatory T cells in splenocytes from DAC and DAC+BMMNC groups was significantly higher than that from the BMMNC and control groups (P < .05). Chimeric rate of the DAC+BMMNC (60%) group was significantly higher than that of the BMMNC group (30%). Moreover, survival time of skin grafts in the DAC+BMMNC group was significantly longer than that in the other 3 groups (P < .001). No death or graft-vs-host disease was observed. ConclusionDAC combined with multiple allogeneic BMMNC infusion could successfully induce specific immune tolerance in mice, which may provide some new strategies to improve immune tolerance after organ transplant.

Comparison of the effect of the aerobic glycolysis inhibitor dichloroacetate and of the Krebs cycle inhibitor LW6 on cellular and humoral alloimmunity.

Cell metabolism is altered during T-cell and B-cell activation and differentiation. Clarifying the exact metabolic shifts may lead to the development of new immunosuppressive medications. In this study, the effect of the aerobic glycolysis inhibitor dichloroacetate (DCA) and of the Krebs cycle enzyme malate dehydrogenase 2 (MDH2) inhibitor LW6 on T-cell alloimmune clonal expansion and on alloantibody production, was evaluated. T-cell clonal expansion was assessed in two-way mixed lymphocyte reaction (MLR). Humoral alloimmunity was evaluated by the alloantibody production in one-way MLR. For this purpose, an antibody-mediated complement-dependent cytotoxicity assay was developed in which the supernatants from one-way MLRs were used against resting peripheral blood mononuclear cells (PBMCs) derived from the same individual that contributed the stimulator cells for the respective MLR. DCA had a minimum effect on alloimmune T-cell clonal expansion, whereas it increased humoral immunity significantly. LW6 decreased both alloimmune T-cell proliferation and alloantibody production. The results indicate that MDH2 may be a perfect target for the development of new immunosuppressive medications, especially when inhibition of both cellular and humoral alloimmunity is desirable.

In vivo immunological properties research on mesenchymal stem cells based engineering cartilage by a dialyzer pocket model.

As the seed cells, the immune properties of the mesenchymal stem cells are important for the tissue engineering restoring effect. But the in vivo research model is lacking. In the study, based on a dialyzer pocket model, changes in immunological properties and the differentiation of seeded mesenchymal stem cells (MSCs) in collagen hydrogel were studied in muscle and articular cavity implantation, respectively. The results showed that collagen hydrogel can induce MSCs to form cartilage tissue, followed by alteration of immunological properties. In muscle implantation, relatively low expression of major histocompatibility complex (MHC) molecules and low level of one-way mixed lymphocyte reactions (MLR) on the seeded MSCs were observed, but only a little cartilage tissue formed. In articular cavity implantation, more cartilage tissue formed, but higher MHC expressions and MLR level were found. Results indicated that the immunomodulation and the cartilage formation of the seeded MSCs will be impacted by the scaffold and the environment of the in vivo implanted site. The dialyzer pocket model can be used for the in vivo research for the MSC-based strategy of the tissue engineering, especially for the optimization of the immunomodulation.