Dll1 Can Function as a Ligand of Notch1 and Notch2 in the Thymic Epithelium.

T-cell development in the thymus is dependent on Notch signaling induced by the interaction of Notch1, present on immigrant cells, with a Notch ligand, delta-like (Dll) 4, on the thymic epithelial cells. Phylogenetic analysis characterizing the properties of the Dll4 molecule suggests that Dll4 emerged from the common ancestor of lobe- and ray-finned fishes and diverged into bony fishes and terrestrial organisms, including mammals. The thymus evolved in cartilaginous fishes before Dll4, suggesting that T-cell development in cartilaginous fishes is dependent on Dll1 instead of Dll4. In this study, we compared the function of both Dll molecules in the thymic epithelium using Foxn1-cre and Dll4-floxed mice with conditional transgenic alleles in which the Dll1 or Dll4 gene is transcribed after the cre-mediated excision of the stop codon. The expression of Dll1 in the thymic epithelium completely restored the defect in the Dll4-deficient condition, suggesting that Dll1 can trigger Notch signaling that is indispensable for T-cell development in the thymus. Moreover, using bone marrow chimeras with Notch1- or Notch2-deficient hematopoietic cells, we showed that Dll1 is able to activate Notch signaling, which is sufficient to induce T-cell development, with both the receptors, in contrast to Dll4, which works only with Notch1, in the thymic environment. These results strongly support the hypothesis that Dll1 regulates T-cell development via Notch1 and/or Notch2 in the thymus of cartilaginous fishes and that Dll4 has replaced Dll1 in inducing thymic Notch signaling via Notch1 during evolution.

Anti-CD80/86 antibodies inhibit inflammatory reaction and improve graft survival in a high-risk murine corneal transplantation rejection model.

We investigated the effects of anti-CD80/86 antibodies in a murine high-risk corneal transplantation rejection model. A mixed lymphocyte reaction (MLR) assay was conducted with anti-CD80/86 antibodies. Inflammatory cytokine levels in the culture supernatant were measured using an enzyme-linked immunosorbent assay. Interferon (IFN)-γ-producing CD4+ T cell frequencies in the MLR were assessed using flow cytometry. In vivo, high-risk corneal allograft survival and IFN-γ-producing CD4+ T cell frequencies in corneal grafts were assessed with intraperitoneal injection of anti-CD80/86 antibodies compared to phosphate-buffered saline (PBS). RNA-sequencing was performed on corneal grafts 2 weeks post-transplantation. Anti-CD80/86 antibodies significantly decreased T-cell proliferation, IFN-γ+-producing CD4+ T cell frequencies, and IFN-γ, interleukin (IL)-1ß, IL-2, IL-10, and tumor necrosis factor-α production in the MLR compared to PBS injection. Intraperitoneal injection of anti-CD80/86 antibodies significantly prolonged corneal graft survival and decreased IFN-γ+-producing CD4+ T cell frequencies compared to PBS injection. Gene set enrichment analysis showed that the gene sets mainly enriched in the control group were related to allograft rejection and inflammatory response compared to PBS injection. Anti-CD80/86 antibodies significantly prolonged corneal graft survival by inhibiting T-cell proliferation and inflammatory response.

A Clinical Trial With Adoptive Transfer of Ex Vivo-induced, Donor-specific Immune-regulatory Cells in Kidney Transplantation-A Second Report.

BACKGROUND: Although the outcome of kidney transplantation (KTx) has improved, various adverse effects of immunosuppressants and chronic rejection aggravate the long-term prognosis of patients. Therefore, the induction of immune tolerance may be an effective therapeutic strategy. METHODS: A clinical trial aiming at immune tolerance induction was conducted in kidney transplant recipients from HLA mismatched living donors by infusing autologous donor-specific regulatory T cells (Treg). To obtain Treg, recipient's peripheral blood mononuclear cells were cocultured with irradiated donor cells in the presence of anti-CD80/CD86 monoclonal antibody for 2 weeks. For preconditioning, splenectomy + cyclophosphamide (CP) was employed in the first series (group A; n = 9). In group B, splenectomy was substituted by preadministration of rituximab (group B; n = 3). In the latest cases, rituximab + rabbit antithymocyte globulin was administered instead of cyclophosphamide (group C; n = 4). Twelve days after KTx, the cultured cells were intravenously infused, and immunosuppressants were gradually tapered thereafter. RESULTS: Although mixed lymphocyte reaction was remarkably suppressed in a donor-specific fashion, 6 out of 9 patients from group A, 1 out of 3 from group B, and 1 out of 4 from group C developed acute rejection within 1 year after KTx. Complete cessation of immunosuppression was not achieved, and a small dose of immunosuppressants was continued. CONCLUSIONS: The adoptive transfer of autologous ex vivo-expanded Treg is 1 of the options to possibly induce alloimmune hyporesponsiveness. However, in the present study, further regimen optimization is still required and should be the focus of future investigations.

Impact of maternal dietary gut microbial metabolites on an offspring's systemic immune response in mouse models.

The gut microbiota has a great impact on the host immune systems. Recent evidence suggests that the maternal gut microbiota affects the immune systems of offspring. Metabolites produced by the gut microbiota play crucial roles in the immune system. Previous studies have also revealed that metabolites such as short-chain fatty acids (SCFAs) and the aryl hydrocarbon receptor (AhR) ligands are involved in host health and diseases. Great progress has been made in understanding the roles of diet-derived SCFAs in the offspring's immune system. The findings to date raise the possibility that maternal dietary soluble fiber intake may play a role in the development of the offspring's systemic immune response. In this review, we summarize the present knowledge and discuss future therapeutic possibilities for using dietary soluble fiber intake against inflammatory diseases.

Delta-like 1 and Delta-like 4 differently require their extracellular domains for triggering Notch signaling in mice.

Delta-like (Dll) 1 and Dll4 differently function as Notch ligands in a context-dependent manner. As these ligands share structural properties, the molecular basis for their functional difference is poorly understood. Here, we investigated the superiority of Dll4 over Dll1 with respect to induction of T cell development using a domain-swapping approach in mice. The DOS motif, shared by Notch ligands-except Dll4-contributes to enhancing the activity of Dll for signal transduction. The module at the N-terminus of Notch ligand (MNNL) of Dll4 is inherently advantageous over Dll1. Molecular dynamic simulation revealed that the loop structure in MNNL domain of Dll1 contains unique proline residues with limited range of motion. The Dll4 mutant with Dll1-derived proline residues showed reduced activity. These results suggest that the loop structure-present within the MNNL domain-with a wide range of motion ensures the superiority of Dll4 and uniquely contributes to the triggering of Notch signaling.

Metastatic seeding of human colon cancer cell clusters expressing the hybrid epithelial/mesenchymal state.

Emerging evidence supports the theory that tumor cell clusters efficiently metastasize to distant organs. However, the roles of epithelial-to-mesenchymal transition (EMT) in metastasizing tumor cell clusters have not yet been fully elucidated. To investigate this issue, tumor fragments were dissected from 40 colorectal cancer (CRC) patients and implanted subcutaneously into immunodeficient mice. We observed that tumors developed from the tumor fragments obtained from 28 of the 40 CRC patients. The tumors were then dissociated into cell suspensions to be orthotopically injected into secondary mice. The tumors from 13 of the 28 patients progressed. Furthermore, metastases formed spontaneously in the liver and lungs from the tumor fragments obtained from 8 of these 13 patients. Moreover, employing a mathematical analysis, we showed that tumor cell clusters seeded these metastases significantly more often than did single tumor cells. Membrane E-cadherin- and nuclear ZEB1-positive tumor cells indicating the hybrid epithelial/mesenchymal state were also detected in primary tumors of various CRC patients, and in the corresponding patient-derived xenografts (PDXs) and circulating tumor cell clusters in the bloodstreams of mice. In contrast, ZEB1 staining was barely detectable in the patient-matched liver metastases presumably developing through mesenchymal-to-epithelial transition. Inhibition of E-cadherin or ZEB1 expression by shRNA notably prevented the PDX-derived tumor organoids from colonizing the liver, when injected intrasplenically into mice, indicating E-cadherin and ZEB1 expressions to be required for their metastatic colonization. Taken together, these findings suggest that the epithelial/mesenchymal state mediates metastatic seeding of human CRC cell clusters into distant organs.

Stromal fibroblasts induce metastatic tumor cell clusters via epithelial-mesenchymal plasticity.

Emerging evidence supports the hypothesis that multicellular tumor clusters invade and seed metastasis. However, whether tumor-associated stroma induces epithelial-mesenchymal plasticity in tumor cell clusters, to promote invasion and metastasis, remains unknown. We demonstrate herein that carcinoma-associated fibroblasts (CAFs) frequently present in tumor stroma drive the formation of tumor cell clusters composed of two distinct cancer cell populations, one in a highly epithelial (E-cadherinhiZEB1lo/neg: Ehi) state and another in a hybrid epithelial/mesenchymal (E-cadherinloZEB1hi: E/M) state. The Ehi cells highly express oncogenic cell-cell adhesion molecules, such as carcinoembryonic antigen-related cell adhesion molecule 5 (CEACAM5) and CEACAM6 that associate with E-cadherin, resulting in increased tumor cell cluster formation and metastatic seeding. The E/M cells also retain associations with Ehi cells, which follow the E/M cells leading to collective invasion. CAF-produced stromal cell-derived factor 1 and transforming growth factor-ß confer the Ehi and E/M states as well as invasive and metastatic traits via Src activation in apposed human breast tumor cells. Taken together, these findings indicate that invasive and metastatic tumor cell clusters are induced by CAFs via epithelial-mesenchymal plasticity.

Role of FBXW7 in the quiescence of gefitinib-resistant lung cancer stem cells in EGFR-mutant non-small cell lung cancer.

Several recent studies suggest that cancer stem cells (CSCs) are involved in intrinsic resistance to cancer treatment. Maintenance of quiescence is crucial for establishing resistance of CSCs to cancer therapeutics. F-box/WD repeat-containing protein 7 (FBXW7) is a ubiquitin ligase that regulates quiescence by targeting the c-MYC protein for ubiquitination. We previously reported that gefitinib-resistant persisters (GRPs) in EGFR-mutant non-small cell lung cancer (NSCLC) cells highly expressed octamer-binding transcription factor 4 (Oct-4) as well as the lung CSC marker CD133, and they exhibited distinctive features of the CSC phenotype. However, the role of FBXW7 in lung CSCs and their resistance to epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors in NSCLC is not fully understood. In this study, we developed GRPs from the two NSCLC cell lines PC9 and HCC827, which express an EGFR exon 19 deletion mutation, by treatment with a high concentration of gefitinib. The GRPs from both PC9 and HCC827 cells expressed high levels of CD133 and FBXW7, but low levels of c-MYC. Cell cycle analysis demonstrated that the majority of GRPs existed in the G0/G1 phase. Knockdown of the FBXW7 gene significantly reduced the cell number of CD133-positive GRPs and reversed the cell population in the G0/G1-phase. We also found that FBXW7 expression in CD133-positive cells was increased and c-MYC expression was decreased in gefitinib-resistant tumors of PC9 cells in mice and in 9 out of 14 tumor specimens from EGFR-mutant NSCLC patients with acquired resistance to gefitinib. These findings suggest that FBXW7 plays a pivotal role in the maintenance of quiescence in gefitinib-resistant lung CSCs in EGFR mutation-positive NSCLC.

High-sensitivity Detection of Micrometastases Generated by GFP Lentivirus-transduced Organoids Cultured from a Patient-derived Colon Tumor.

Despite current advances in human colorectal cancer (CRC) treatment, few radical therapies are effective for the late stages of CRC. To overcome this clinical challenge, tumor xenograft mouse models using long-established human carcinoma cell lines and many transgenic mouse models with tumors have been developed as preclinical models. They partially mimic the features of human carcinomas, but often fail to recapitulate the key aspects of human malignancies including invasion and metastasis. Thus, alternative models that better represent the malignant progression in human CRC have long been awaited. We herein show generation of patient-derived tumor xenografts (PDXs) by subcutaneous implantation of small CRC fragments surgically dissected from a patient. The colon PDXs develop and histopathologically resemble the CRC in the patient. However, few spontaneous micrometastases are detectable in conventional cross-sections of affected distant organs in the PDX model. To facilitate the detection of metastatic dissemination into distant organs, we extracted the tumor organoid cells from the colon PDXs in culture and infected them with GFP lentivirus prior to injection into highly immunodeficient NOD/Shi-scid IL2Rγnull (NOG) mice. Orthotopically injected PDX-derived CRC organoid cells consistently form primary tumors positive for GFP in recipient mice. Moreover, spontaneously developing micrometastatic colonies expressing GFP are notably detected in the lungs of these mice by fluorescence microscopy. Moreover, intrasplenic injection of CRC organoids frequently produces hepatic colonization. Taken together, these findings indicate GFP-labelled PDX-derived CRC organoid cells to be visually detectable during a multistep process termed the invasion-metastasis cascade. The described protocols include the establishment of PDXs of human CRC and 3D culture of the corresponding CRC organoid cells transduced by GFP lentiviral particles.

Comparative immunity of antigen recognition, differentiation, and other functional molecules: similarities and differences among common marmosets, humans, and mice.

The common marmoset (CM; Callithrix jacchus) is a small New World monkey with a high rate of pregnancy and is maintained in closed colonies as an experimental animal species. Although CMs are used for immunological research, such as studies of autoimmune disease and infectious disease, their immunological characteristics are less defined than those of other nonhuman primates. We and others have analyzed antigen recognition-related molecules, the development of hematopoietic stem cells (HSCs), and the molecules involved in the immune response. CMs systemically express Caja-G, a major histocompatibility complex class I molecule, and the ortholog of HLA-G, a suppressive nonclassical HLA class I molecule. HSCs express CD117, while CD34 is not essential for multipotency. CD117+ cells developed into all hematopoietic cell lineages, but compared with human HSCs, B cells did not extensively develop when HSCs were transplanted into an immunodeficient mouse. Although autoimmune models have been successfully established, sensitization of CMs with some bacteria induced a low protective immunity. In CMs, B cells were observed in the periphery, but IgG levels were very low compared with those in humans and mice. This evidence suggests that CM immunity is partially suppressed systemically. Such immune regulation might benefit pregnancy in CMs, which normally deliver dizygotic twins, the placentae of which are fused and the immune cells of which are mixed. In this review, we describe the CM immune system and discuss the possibility of using CMs as a model of human immunity.

The response of common marmoset immunity against cedar pollen extract.

The in vivo model of pollinosis has been established using rodents, but the model cannot completely mimic human pollinosis. We used Callithrix jacchus, the common marmoset (CM), to establish a pollinosis animal model using intranasal weekly administration of cedar pollen extract with cholera toxin adjuvant. Some of the treated CMs exhibited the symptoms of snitching, excess nasal mucus and/or sneezing, but the period was very short, and the symptoms disappeared after several weeks. The CD4+CD25+ cell ratio in the peripheral blood increased in CMs quickly after the nasal administration of cedar pollen extract, but the timing was not parallel with the symptoms. IL-10 mRNA was enhanced in the peripheral blood mononuclear cells (PBMCs), suggesting CM-induced tolerance for cedar pollen administration. Similarly, Foxp3 mRNA was also detected in the PBMC. Additive sensitization of these CMs with Ascaris egg administration did not enhance chronic inflammation of type 1 allergy to induce the symptoms. These results suggest that the environmental immune cells develop transient allergic symptoms and subsequent immune-tolerance in the intranasally sensitized CMs.

CD155-Transducing Signaling through TIGIT Plays an Important Role in Transmission of Tolerant State and Suppression Capacity.

The precise mechanism of how the regulatory T cell population elicits and maintains tolerant state in activated T cells is poorly understood. To address this issue, we established an in vitro coculture system using mouse T cells and showed that tolerant state is serially passed from preinduced-tolerant T cells into new TCR-stimulated T cells across generations in a dendritic cell-independent manner. In this successive induction process of tolerant state, TIGIT was found to play an important role: TIGIT expression on induced-tolerant T cells was promoted in stimulated T cells cocultured with the tolerant cells. In addition, these stimulated T cells in the coculture also expressed high B lymphocyte-induced maturation protein 1 accompanied by IL-2 suppression. Because CD155, a partner of TIGIT, is known to transduce signaling inside by trans-interaction with its ligands, these phenotypical changes in TCR-stimulated naive T cells were reproduced when naive T cells were double cross-linked by CD3 and CD155. These results indicate that TIGIT enhanced on tolerant T cells may function as a ligand of its paired receptor CD155 to transduce signaling into its expressing naive T cells to accelerate new TIGIT expressions as well as IL-2 suppression via B lymphocyte-induced maturation protein 1 enhancement. In consideration of these results, we propose a novel process in which tolerant state in T cell population is maintained by successive generation of new tolerant T cells from naive T cells as one of the regulating mechanisms in immune responses.

Maternal High Fiber Diet during Pregnancy and Lactation Influences Regulatory T Cell Differentiation in Offspring in Mice.

Short-chain fatty acids (SCFAs), the end products of dietary fiber, influence the immune system. Moreover, during pregnancy the maternal microbiome has a great impact on the development of the offspring's immune system. However, the exact mechanisms by which maternal SCFAs during pregnancy and lactation influence the immune system of offspring are not fully understood. We investigated the molecular mechanisms underlying regulatory T cell (Treg) differentiation in offspring regulated by a maternal high fiber diet (HFD). Plasma levels of SCFAs in offspring from HFD-fed mice were higher than in those from no fiber diet-fed mice. Consequently, the offspring from HFD-fed mice had higher frequencies of thymic Treg (tTreg) and peripheral Tregs We found that the offspring of HFD-fed mice exhibited higher autoimmune regulator (Aire) expression, a transcription factor expressed in the thymic microenvironment, suggesting SCFAs promote tTreg differentiation through increased Aire expression. Notably, the receptor for butyrate, G protein-coupled receptor 41 (GPR41), is highly expressed in the thymic microenvironment and Aire expression is not increased by stimulation with butyrate in GPR41-deficient mice. Our studies highlight the significance of SCFAs produced by a maternal HFD for Treg differentiation in the thymus of offspring. Given that Aire expression is associated with the induction of tTregs, the maternal microbiome influences Treg differentiation in the thymus of offspring through GPR41-mediated Aire expression.

NOG-hIL-4-Tg, a new humanized mouse model for producing tumor antigen-specific IgG antibody by peptide vaccination.

Immunodeficient mice transplanted with human peripheral blood mononuclear cells (PBMCs) are promising tools to evaluate human immune responses to vaccines. However, these mice usually develop severe graft-versus-host disease (GVHD), which makes estimation of antigen-specific IgG production after antigen immunization difficult. To evaluate antigen-specific IgG responses in PBMC-transplanted immunodeficient mice, we developed a novel NOD/Shi-scid-IL2rγnull (NOG) mouse strain that systemically expresses the human IL-4 gene (NOG-hIL-4-Tg). After human PBMC transplantation, GVHD symptoms were significantly suppressed in NOG-hIL-4-Tg compared to conventional NOG mice. In kinetic analyses of human leukocytes, long-term engraftment of human T cells has been observed in peripheral blood of NOG-hIL-4-Tg, followed by dominant CD4+ T rather than CD8+ T cell proliferation. Furthermore, these CD4+ T cells shifted to type 2 helper (Th2) cells, resulting in long-term suppression of GVHD. Most of the human B cells detected in the transplanted mice had a plasmablast phenotype. Vaccination with HER2 multiple antigen peptide (CH401MAP) or keyhole limpet hemocyanin (KLH) successfully induced antigen-specific IgG production in PBMC-transplanted NOG-hIL-4-Tg. The HLA haplotype of donor PBMCs might not be relevant to the antibody secretion ability after immunization. These results suggest that the human PBMC-transplanted NOG-hIL-4-Tg mouse is an effective tool to evaluate the production of antigen-specific IgG antibodies.

Generation of a Nonhuman Primate Model of Severe Combined Immunodeficiency Using Highly Efficient Genome Editing.

Recent advances in genome editing have facilitated the generation of nonhuman primate (NHP) models, with potential to unmask the complex biology of human disease not revealed by rodent models. However, their broader use is hindered by the challenges associated with generation of adult NHP models as well as the cost of their production. Here, we describe the generation of a marmoset model of severe combined immunodeficiency (SCID). This study optimized zinc-finger nucleases (ZFNs) and transcription activator-like effector nucleases (TALENs) to target interleukin-2 receptor subunit gamma (IL2RG) in pronuclear stage marmoset embryos. Nine of 21 neonates exhibited mutations in the IL2RG gene, concomitant with immunodeficiency, and three neonates have currently survived from 240 days to 1.8 years. Our approach demonstrates highly efficient production of founder NHP with SCID phenotypes, with promises of multiple pre-clinical and translational applications.

Inhibitory function of NKT cells during early induction phase of nickel allergy.

Until now, metal allergies have been regarded as a Th1-type immune response.　However, because the contribution of a Th2-type immune response has been suggested by clinical findings, we previously examined the Th2-type immune response during the development of metal allergies using a GATA-3 transgenic (GATA-3 Tg) mouse model. As a result, a Th2-type immunization reaction was suggested to be involved in the early phase of metal allergies. Recently, the involvement of NKT cells in metal allergies has been suggested. We examined this possibility using the activation of NKT cells and an NKT cell-deficient mouse model to determine the contribution of NKT cells to nickel allergy in the present study. In NKT cell-deficient mice, ear swelling was remarkably increased, compared with that in control mice. Also, in mice that had been treated with α-galactosylceramide (α-GalCer) to activate NKT cells, the ear swelling response was remarkably inhibited, compared with that in untreated mice. These facts show that NKT cells are involved in the inhibition of nickel allergy-induced ear swelling responses.

A pilot study of operational tolerance with a regulatory T-cell-based cell therapy in living donor liver transplantation.

UNLABELLED: Potent immunosuppressive drugs have significantly improved early patient survival after liver transplantation (LT). However, long-term results remain unsatisfactory because of adverse events that are largely associated with lifelong immunosuppression. To solve this problem, different strategies have been undertaken to induce operational tolerance, for example, maintenance of normal graft function and histology without immunosuppressive therapy, but have achieved limited success. In this pilot study, we aimed to induce tolerance using a novel regulatory T-cell-based cell therapy in living donor LT. Adoptive transfer of an ex vivo-generated regulatory T-cell-enriched cell product was conducted in 10 consecutive adult patients early post-LT. Cells were generated using a 2-week coculture of recipient lymphocytes with irradiated donor cells in the presence of anti-CD80/86 monoclonal antibodies. Immunosuppressive agents were tapered from 6 months, reduced every 3 months, and completely discontinued by 18 months. After the culture, the generated cells displayed cell-number-dependent donor-specific inhibition in the mixed lymphocyte reaction. Infusion of these cells caused no significant adverse events. Currently, all patients are well with normal graft function and histology. Seven patients have completed successful weaning and cessation of immunosuppressive agents. At present, they have been drug free for 16-33 months; 4 patients have been drug free for more than 24 months. The other 3 recipients with autoimmune liver diseases developed mild rejection during weaning and then resumed conventional low-dose immunotherapy. CONCLUSIONS: A cell therapy using an ex vivo-generated regulatory T-cell-enriched cell product is safe and effective for drug minimization and operational tolerance induction in living donor liver recipients with nonimmunological liver diseases. (Hepatology 2016;64:632-643).

Release from Th1-type immune tolerance in spleen and enhanced production of IL-5 in Peyer's patch by cholera toxin B induce the glomerular deposition of IgA.

We examined the pathogenesis of glomerular damage in Th2 type-dependent GATA-3 transgenic (GATA-3 Tg) mice with IgA nephropathy (IgAN). GATA-3 Tg mice were immunized orally using OVA plus cholera toxin B (CTB), and measurement of the serum IgA antibody level and histopathological examination were performed. Marked increases in the serum levels of OVA-specific IgA antibody, IgA and IgG, C3 deposits analogous to those seen in IgAN, and expansion of the matrix in association with mesangial cell proliferation were observed. Furthermore, glomerular IgA deposits were co-localized with mannan-binding lectin (MBL) deposits, which might actually have been abnormal IgA deposits. In GATA-3/TCR-Tg mice that had been orally sensitized with CTB plus OVA and were re-stimulated with OVA in vitro, cultured Peyer's patch cells showed the enhanced production of IL-5 and supernatants from cultures of spleen cells showed a reduction of TGF-ß production with a simultaneous increase in IL-2 production and the recovery of IFN-γ formation. The amount of TGF-ß produced by the spleen cells was found to be correlated with the amount of IFN-γ and IL-IL-2 produced by the cells. Also, the percentage of regulatory T cells (Treg) in the spleens of mice sensitized with OVA plus CTB was lower than that in mice orally sensitized with OVA alone. These results suggest that the increased production of IL-5 from Peyer's patch cells (PPc) and the restored Th1-type immune response might cause the production of abnormal IgA and might induce the deposition of IgA in glomeruli.

Treatment with Anti-FcεRIα (MAR-1) Antibody Prevents Acute Islet Allograft Rejection in a Murine Model.

OBJECTIVE: Various immunological strategies for tolerance induction against allogeneic tissue grafts (allografts) have been tested in islet transplant recipients; for example, T cell activating co-stimulatory pathway blockade has been shown to prolong islet allograft survival. However, little is known about whether infiltrating inflammatory cells (e.g., basophils) affect islet allograft fates before antigen-specific immune cell development. Herein, we treated mice with a basophil-specific monoclonal antibody (mAb) and examined whether early acute-phase islet allograft rejection could be prevented in recipients. METHODS: Pancreatic islets isolated from C57BL/6 (H-2b) or DBA/2 (H-2d) mice were transplanted under the renal capsules of C57BL/6 recipient mice. Recipients receiving allografts were administered the anti-basophil mAb MAR-1 to examine the antibody-mediated effect on graft survival. At days 4 and 7 post-transplantation, graft-bearing recipient kidneys were harvested for immunohistological analysis and stained with anti-insulin antibody to compare the sizes of grafted islets. RESULTS: On day 7 post-transplantation, the transplanted pancreatic islet clusters in allograft-recipient kidneys had rapidly decreased in size, whereas those in syngeneic recipients remained larger in both size and number. However, MAR-1-treated recipients had increased the numbers of larger insulin-positive allograft islet cell clusters. CONCLUSION: Basophil-specific mAb treatment contributes to enhance and prolong transplanted islet survival in allogeneic recipient mice.

Requirement of full TCR repertoire for regulatory T cells to maintain intestinal homeostasis.

The regulation of intestinal homeostasis by the immune system involves the dynamic interplay between gut commensal microbiota and resident immune cells. It is well known that a large and diverse lymphocyte antigen receptor repertoire enables the immune system to recognize and respond to a wide range of invading pathogens. There is also an emerging appreciation for a critical role the T-cell receptor (TCR) repertoire serves in the maintenance of peripheral tolerance by regulatory T cells (Tregs). Nevertheless, how the diversity of the TCR repertoire in Tregs affects intestinal homeostasis remains unknown. To address this question, we studied mice whose T cells express a restricted TCR repertoire. We observed the development of spontaneous colitis, accompanied by the induction of T-helper type 17 cells in the colon that is driven by gut commensal microbiota. We provide further evidence that a restricted TCR repertoire causes a loss of tolerogenicity to microbiota, accompanied by a paucity of peripherally derived, Helios(-) Tregs and hyperactivation of migratory dendritic cells. These results thus reveal a new facet of the TCR repertoire in which Tregs require a diverse TCR repitoire for intestinal homeostasis, suggesting an additional driving force in the evolutional significance of the TCR repertoire.