Cell-mediated Immune Tolerance Research Articles

Gut bacteria-derived serotonin promotes immune tolerance in early life.

The gut microbiota promotes immune system development in early life, but the interactions between the gut metabolome and immune cells in the neonatal gut remain largely undefined. Here, we demonstrate that the neonatal gut is uniquely enriched with neurotransmitters, including serotonin, and that specific gut bacteria directly produce serotonin while down-regulating monoamine oxidase A to limit serotonin breakdown. We found that serotonin directly signals to T cells to increase intracellular indole-3-acetaldehdye and inhibit mTOR activation, thereby promoting the differentiation of regulatory T cells, both ex vivo and in vivo in the neonatal intestine. Oral gavage of serotonin into neonatal mice resulted in long-term T cell-mediated antigen-specific immune tolerance toward both dietary antigens and commensal bacteria. Together, our study has uncovered an important role for specific gut bacteria to increase serotonin availability in the neonatal gut and identified a function of gut serotonin in shaping T cell response to dietary antigens and commensal bacteria to promote immune tolerance in early life.

Alterations of milk oligosaccharides in mothers with gestational diabetes mellitus impede colonization of beneficial bacteria and development of RORγt+ Treg cell-mediated immune tolerance in neonates

ABSTRACT Gestational diabetes mellitus (GDM) is an increasing public health concern that significantly increases the risk of early childhood allergic diseases. Altered maternal milk glycobiome may strongly affect gut microbiota and enteric-specific Treg cell-mediated development of immune tolerance in GDM infants. In this study, we found that, compared with healthy Chinese mothers, mothers with GDM had significantly lower levels of total and specific human milk oligosaccharides (HMOs) in their colostrum that subsequently increased with extension of lactation. This alteration in HMO profiles significantly delayed colonization of Lactobacillus and Bifidobacterium spp. in their breast-fed infants, resulting in a distinct gut microbial structure and metabolome. Further experiments in GDM mouse models indicated that decreased contents of milk oligosaccharides, mainly 3ʹ-sialyllactose (3ʹ-SL), in GDM maternal mice reduced colonization of bacteria, such as L. reuteri and L. johnsonii, in the neonatal gut, which impeded development of RORγt+ regulatory T (Treg) cell-mediated immune tolerance. Treatment of GDM neonates with 3ʹ-SL, Lactobacillus reuteri (L. reuteri) and L. johnsonii promoted the proliferation of enteric Treg cells and expression of transcription factor RORγt, which may have contributed to compromising ovalbumin (OVA)-induced allergic responses. In vitro experiments showed that 3ʹ-SL, metabolites of L. johnsonii, and lysates of L. reuteri stimulated differentiation of mouse RORγt+ Treg cells through multiple regulatory effects on Toll-like receptor, MAPK, p53, and NOD-like receptor signaling pathways. This study provides new ideas for the development of gut microbiota and immune tolerance in GDM newborns.

IKKβ increases neuropilin-2 and promotes the inhibitory function of CD9+ Bregs to control allergic diseases

Regulatory B cells (Bregs) potently suppress immune disorders, including allergic contact hypersensitivity (CHS). IKKβ overactivation is prominent in various inflammatory diseases. However, its effect on Bregs has not been defined. This study is to investigate the new regulator and inhibitory mechanism of Bregs. IkkβC46A transgenic mice with a Cys46 mutation, resulting in increased IKKβ activation, were employed for analysis. IL-10-competent CD9+ Bregs were expanded in IkkβC46A mice and B cell specific-IkkβC46A mutation mice. IkkβC46A mutant CD9+ Bregs had stronger suppressive effects on CD4+ and CD8+ T cells in vitro and CHS responses in vivo. The inhibitory CD9+ Bregs from IkkβC46A mice were characterized by upregulated Neuropilin 2 (Nrp2) and IL-10 in comparison with that of Ikkβwt mice. Interestingly, increased expression of Nrp2 was observed in CD9+ Bregs compared with that of CD9- B cells in wild-type mice. The suppressive activity of wild-type CD9+ Bregs in vitro was attenuated by inhibition of Nrp2 on Bregs or silencing its ligand Sema3f on CD4+ T cells. Our findings delineate a distinct role of IKKβ activation in enhancing Bregs to disturb the immune balance. It identifies Nrp2 as a novel regulatory molecule of Bregs that partly contributes to B cell-mediated immune tolerance.

A Stk4-Foxp3-NF-κB p65 transcriptional complex promotes Treg cell activation and homeostasis.

The molecular programs involved in regulatory T (Treg) cell activation and homeostasis remain incompletely understood. Here, we show that T cell receptor (TCR) signaling in Treg cells induces the nuclear translocation of serine/threonine kinase 4 (Stk4), leading to the formation of an Stk4-NF-κB p65-Foxp3 complex that regulates Foxp3- and p65-dependent transcriptional programs. This complex was stabilized by Stk4-dependent phosphorylation of Foxp3 on serine-418. Stk4 deficiency in Treg cells, either alone or in combination with its homolog Stk3, precipitated a fatal autoimmune lymphoproliferative disease in mice characterized by decreased Treg cell p65 expression and nuclear translocation, impaired NF-κB p65-Foxp3 complex formation, and defective Treg cell activation. In an adoptive immunotherapy model, overexpression of p65 or the phosphomimetic Foxp3S418E in Stk3/4-deficient Treg cells ameliorated their immune regulatory defects. Our studies identify Stk4 as an essential TCR-responsive regulator of p65-Foxp3-dependent transcription that promotes Treg cell-mediated immune tolerance.

Influences of non-IgE-mediated cow's milk protein allergy-associated gut microbial dysbiosis on regulatory T cell-mediated intestinal immune tolerance and homeostasis

Gut microbial dysbiosis is closely associated with cow's milk protein allergy (CMPA) during infancy. Recent research has highlighted the crucial role of the commensal microbiota-induced intestinal regulatory T (Treg) cell response in the development of oral tolerance and protection against IgE-mediated food allergies. However, the influences of CMPA (particularly non-IgE-mediated CMPA)-associated microbial dysbiosis on Treg cell-mediated intestinal immune tolerance and homeostasis remain poorly characterized. To investigate this issue, fecal microbiota from infant donors with food protein-induced allergic proctocolitis (FPIAP) associated with cow's milk, which is the most frequent clinical type of non-IgE-mediated gastrointestinal CMPA, and from age-matched healthy controls were transplanted into germ-free mice in this study. Two weeks post fecal microbiota transplantation, the gut microbiome of the recipient mice was analyzed by 16S rRNA gene sequencing, and the intestinal immunological alterations associated with the Treg cell compartment and intestinal immune homeostasis were detected. The specific gut microbial phylotypes that were potentially responsible for the disruption of intestinal immune homeostasis were also analyzed. We observed that the main characteristics of the gut microbiome in infant donors could be stably maintained in recipient mice. We also found that mice colonized with the gut microbiome from infants with cow's milk-induced FPIAP showed significant deficiencies in the accumulation and function of intestinal Treg cells. Furthermore, these mice showed disrupted intestinal immune homeostasis, which was characterized by an overactivated Th2 biased immune response. We further identified two potentially pathogenic genera that contribute to this disruption. Overall, our results highlight a destructive effect of non-IgE-mediated CMPA-associated microbial dysbiosis on intestinal immune tolerance and homeostasis. We believe these findings will help improve our understanding of the gut microbiota-mediated pathogenesis of non-IgE-mediated CMPA in the future.

RIP3 Blockade Drives Myeloid-Derived Suppressor Cell-Mediated Immune Tolerance in Immune-Mediated Hepatitis

Background: Excessive and uncontrolled immune activation plays a deleterious role in liver damage of autoimmune hepatitis (AIH), thus, it`s of great significance to identify the regulation of immune tolerance. Receptor-interacting protein kinase 3 (RIP3) has been found to be down-regulated in tumor tissues and mediates tumor immune evasion. However, the role of RIP3 in AIH remains elusive. We aimed to investigate the role of RIP3 in the regulation of inflammation and immune tolerance in immune-mediated hepatitis (IMH). Methods: RIP3 expression was evaluated in the livers of AIH patients and mice models. Mice were treated with GSK872, a RIP3 specific inhibitor, or glucocorticoid dexamethasone before concanavalin A (ConA)-induced IMH. Real-time PCR, western blotting, and flow cytometry served to explore the molecular mechanisms involved. The depleting anti-mouse Gr-1 antibody and isotype control were used for further determine the role of MDSCs in GSK872 treatment. Findings: AIH patients and mice model displayed pronounced RIP3 activation in the liver tissues. RIP3 blockade by GSK872 prevented ConA-induced IMH by reduced hepatic proinflammatory cytokines and immune cells including Th17 cells and macrophages. Further experiments revealed that RIP3 inhibition resulted in an increase in CD11b+ Gr-1+ MDSCs with immunoregulatory properties in the livers, spleen, and peripheral blood. Moreover, the depletion of Gr-1+ MDSCs abrogated the protective effect and immune suppression function of GSK872 in ConA-induced IMH. Interpretation: RIP3 blockade prevents ConA-induced IMH through a MDSC-dependent mechanism. Inhibition of RIP3 kinase may be a novel therapeutic avenue for AIH treatment. Funding Statement: The study was supported by the National Natural Science Foundation of China (81860109). Declaration of Interests: The authors declare no conflicts of interest. Ethics Approval Statement: This study was approved by the Ethics Committee of Tianjin Medical University General Hospital, and all participants provided signed informed consents. The animal use protocol has been reviewed and approved by the Animal Ethical and Welfare Committee of Tianjin Medical University, Approval No. IRB2020-WZ-175.

Protopanaxadiol improves endometriosis associated infertility and miscarriage in sex hormones receptors-dependent and independent manners.

Background: Patients with endometriosis (EMs) have high risks of infertility and spontaneous abortion. How to remodel the fertility of patients with EMs has always been the hot spot and difficulty in the field of reproductive medicine. As an aglycone of ginsenosides, protopanaxadiol (PPD) possesses pleiotropic biological functions and has high medicinal values. We aimed to investigate the effect and potential mechanism of PPD in the treatment of EMs-associated infertility and spontaneous abortion.Methods: The EMs mice models were constructed by allotransplantation. The pregnancy rates, embryo implantation numbers and embryo resorption rates of control and EMs were counted. RNA sequencing, qRT-PCR, enzyme linked immunosorbent assay (ELISA) and FCM analysis were performed to screen and confirm the expression of endometrial receptivity/decidualization-related molecules, inflammation cytokines and NK cell function-related molecules in vitro and/or in vivo. The SWISS Target Prediction, STRING and Cytoscape were carried out to predict the potential cellular sensory proteins, the protein-protein interaction (PPI) network between sensory proteins and fertility-related molecules, respectively. Micro-CT detection, liver and kidney function tests were used to evaluate the safety.Results: Here, we observe that PPD significantly up-regulates endometrial receptivity-related molecules (e.g., Lif, Igfbp1, Mmps, collagens) and restricts pelvic inflammatory response (low levels of IL-12 and IFN-γ) of macrophage, and further remodel and improve the fertility of EMs mice. Additionally, PPD increases the expression of decidualization-related genes and Collagens, and promotes the proliferation, residence, immune tolerance and anagogic functions of decidual NK cells (low levels of CD16 and NKp30, high levels of Ki67, VEGF, TGF-β) in pregnant EMs mice, and further triggers decidualization, decidual NK cell-mediated maternal-fetal immune tolerance and angiogenesis, preventing pregnant EMs mice from miscarriage. Mechanically, these effects should be dependent on ESRs, PGR and other sensory proteins (e.g., AR). Compared with GnRHa (the clinic first-line drug for EMs), PPD does not lead to the decline of serum estrogen and bone loss.Conclusion: These data suggest that PPD prevents EMs-associated infertility and miscarriage in sex hormones receptors-dependent and independent manners possibly, and provides a potential therapeutic strategy with high efficiency and low side effects to remodels the fertility of patients with EMs.

Expression Level of IL-17 in Peripheral Blood of Patients with Late Pregnancy and Diagnosis of Maternal-Fetal Tolerance Based on Brain MRI Image Segmentation Algorithm.

Objectives:To study the expression of IL-17 in peripheral blood and its effect on maternal-fetal tolerance in patients with eclampsia in late pregnancy using MRI image segmentation algorithm.Methods:Thirty-nine patients with severe preeclampsia and eclampsia with brain symptoms were examined by cranial MRI. Pregnant women with 32 weeks of pregnancy were selected to detect the percentage of Th17 and Treg cells in CD4 + T lymphocytes and the expression of cytokines IL-17 and IL-10 in peripheral blood.Results:MRI examination was normal in 26 cases, 9 cases showed reversible posterior encephalopathy syndrome, three cases were cerebral hemorrhage, and one case was intracranial cavernous sinus thrombosis. two. Compared with the mild preeclampsia group, the relative number of Thl7 cells increased and that of Treg cells decreased in the severe preeclampsia group (P>0.05).Conclusion:The major types of cerebrovascular diseases (CVD) in severe preeclampsia and eclampsia were reversible posterior encephalopathy syndrome and cerebral hemorrhage. It was speculated that the damage to the blood-brain barrier may play an important role in the pathogenesis. The balance of the number of Th17 cells/the number of Treg cells was more inclined to the Th17 cell-mediated pro-inflammatory state, Treg cell-mediated immune tolerance decreases, and it becomes more obvious with the worsening of the disease.

T cell Tolerance in Early Life.

T cell-mediated immune tolerance is a state of unresponsiveness of T cells towards specific self or non-self antigens. This is particularly essential during prenatal/neonatal period when T cells are exposed to dramatically changing environment and required to avoid rejection of maternal antigens, limit autoimmune responses, tolerate inert environmental and food antigens and antigens from non-harmful commensal microorganisms, promote maturation of mucosal barrier function, yet mount an appropriate response to pathogenic microorganisms. The cell-intrinsic and cell extrinsic mechanisms promote the generation of prenatal/neonatal T cells with distinct features to meet the complex and dynamic need of tolerance during this period. Reduced exposure or impaired tolerance in early life may have significant impact on allergic or autoimmune diseases in adult life. The uniqueness of conventional and regulatory T cells in human umbilical cord blood (UCB) may also provide certain advantages in UCB transplantation for hematological disorders.

Donor-Specific Regulatory T Cell-Mediated Immune Tolerance in an Intrahepatic Murine Allogeneic Islet Transplantation Model with Short-Term Anti-CD154 mAb Single Treatment

Anti-CD154 blockade-based regimens remain unequaled in prolonging graft survival in various organ transplantation models. Several studies have focused on transplantation tolerance with the anti-CD154 blockade, but none of these studies has investigated the mechanisms associated with its use as the sole treatment in animal models, delaying our understanding of anti-CD154 blockade-mediated immune tolerance. The purpose of this study was to investigate the mechanism underlying the anti-CD154 monoclonal antibody (mAb) blockade in inducing immune tolerance using an intrahepatic murine allogeneic islet transplantation model. Allogeneic BALB/c AnHsd (BALB/c) islets were infused into the liver of diabetic C57BL/6 (B6) mice via the cecal vein. Anti-CD154 mAb (MR1) was administered on −1, 0, 1, 3, 5, and 7 d posttransplantation at 0.5 mg per mouse. We showed that short-term MR1 monotherapy could prolong the allogeneic islet grafts to more than 250 d in the murine intrahepatic islet transplantation model. The second islet grafts transplanted under the kidney capsule of the recipients were protected from rejection. We also found that rejection of same-donor skin grafts transplanted to the tolerant mice was modestly delayed. Using a DEREG mouse model, FoxP3+ regulatory T (Treg) cells were shown to play important roles in transplantation tolerance. In mixed lymphocyte reactions, Treg cells from the tolerant mice showed more potency in suppressing BALB/c splenocyte-stimulated Teff cell proliferation than those from naïve mice. In this study, we demonstrated for the first time that a short-term anti-CD154 mAb single treatment could induce FoxP3+ Treg cell-mediated immune tolerance in the intrahepatic murine allogeneic islet transplantation model.

Increased Serum Levels of Soluble B7-H4 in Patients with Systemic Lupus Erythematosus.

Members of B7 family are reported to regulate lymphocytes activation, transmit both costimulatory and co-inhibitory signals, control T cell-mediated immune responses and tolerance. Among which B7-H4 is reported to regulate the immune response negatively. To investigate the plasma concentration of soluble B7-H4 (sB7-H4) and its clinical significance in systemic lupus erythematosus (SLE). Fifty-six SLE patients with or without active SLE (ASLE) and 29 age- and gender-matched healthy volunteers were recruited. Plasma concentration of sB7-H4 was measured using sandwich ELISA kits. Compared with healthy subjects, the concentration of sB7-H4 was significantly higher in patients with SLE (p=0.006). Plasma sB7-H4 concentration in patients with lupus nephritis (LN) were also significantly higher than healthy subjects (p=0.008), but no difference was found between LN and SLE patients without LN (non-LN). Additionally, the sB7-H4 concentration in patients was negatively correlated with the SLE disease activity index score (SLEDAI) (r=-0.3055, p=0.022). Compared with inactive disease, the concentration of sB7-H4 in ASLE patients was significantly lower (p=0.002). There were statistical significances between the positive and negative groups with decreased leukocytes or thrombocytes (p=0.012; p=0.033; respectively), but no statistically significant difference was found in other positive and negative serum laboratory indicators. The increased level of sB7-H4 in patients suggests that this pathway might be involved in the pathogenesis of SLE. However, the exact mechanism or physiological role of sB7-H4 in SLE pathogenesis remains to be investigated.

PD-1-Mediated T Cell Exhaustion Is Prevalent Among Patients with MPN-Associated Myelofibrosis Independent of JAK1/2 Inhibition

Background: Primary myelofibrosis (PMF), post-polycythemia vera MF (post-PV MF) and post-essential thrombocythemia MF (post-ET MF) are characterized by expansion of the neoplastic clone and by progressive bone marrow (BM) fibrosis. Like in other hematologic malignancies, in most patients with MF the immune system is significantly deregulated: MF patients' plasma cytokine and chemokine levels are markedly increased and their normal T cell subset distribution is significantly altered. Although treatment with the Janus kinase (JAK)-1/2 inhibitor ruxolitinib significantly decreases cytokine/chemokine levels, reduces spleen size, and improves symptoms and quality of life, it does not reverse BM fibrosis nor does it halt the propagation of the neoplastic clone. The T cell immune checkpoint programmed cell death protein-1 (PD-1) promotes immune tolerance by binding to the tumor's cell surface PD-1 ligand (PD-L1). Whereas the importance of T cell-mediated immune tolerance in MF has been documented and trials evaluating clinical benefits of PD1/PD-L1 checkpoint inhibition are ongoing, little is known about the effect of ruxolitinib on PD-1 expression in T cell subsets. Therefore we systematically analyzed MF patients circulating T cells' surface marker expression prior to and during ruxolitinib treatment.Methods: Peripheral blood cells were obtained from well-characterized PMF, post-PV MF and post-ET MF patients prior to and during the course of treatment with ruxolitinib (n=47) and, as control, from age-matched healthy donors (n=28). The proportion of PD-1-expressing CD4+ and CD8+ cells was assessed using multiparameter flow cytometry. Naïve, central memory, effector memory, and effector T cell subsets were defined based on CD45RO and CD27 cell surface antigen expression.Results: A significantly high number of circulating T cells co-expressing CD4+/PD-1+ and CD8+/PD-1+ was found in MF patients compared to age-matched healthy individuals (5.3±4.1% vs. 3.4±1.7%, P=0.028; 7.1±4.4% vs. 3.8±2.3%, P=0.001). Whereas MF patients' naïve T cells harbored an increased number of cells co-expressing CD8+/PD-1+ (P=0.007), but not CD4+/PD-1+, their T central memory cells had a high proportion of cells co-expressing CD4+/PD-1+ and CD8+/PD-1+ (P<0.001; P<0.001). Similarly, a high proportion of circulating PD-1+ T effector memory cells (P<0.001; P<0.001), and T effector cells (P=0.013; P<0.001) was found in MF patients compared to the same cell subsets in healthy age-matched individuals. The proportions of PD-1+ T cells significantly correlated with LDH level and DIPSS score (CD4+ T cells), monocyte count (CD8+ T cells), and total leukocyte count and spleen size (both subsets). Remarkably, the percentage of PD-1+ cells within naïve and central memory CD8+ T cell populations was significantly higher in MF patients with circulating blasts (P=0.036). To determine the effects of ruxolitinib administration, we performed repeated flow cytometry analyses on MF patients' T cells prior to and during treatment (median duration: 4.3 years). Overall, no significant change in PD-1 expression levels in any of the different T cell subsets was detected over the entire treatment period. However, a significant reduction in percentage of cells co-expressing CD4+/PD-1+ and CD8+/ PD-1+ compared to treatment baseline (4.4±0.4% vs. 7.6±2.0%, P=0.011; 6.3±0.6% vs. 10.4±2.7%, P=0.021) was found in patients whose spleen size was reduced after 6 months of treatment.Conclusions: In patients with MF, circulating T cells express high levels of PD-1. While not restricted to a particular stage of T cell differentiation, the correlation between PD-1-expressing T cells and distinct clinical parameters suggests that increased PD-1 levels might induce immune exhaustion in T cell subsets in different ways. Although ruxolitinib significantly inhibits the JAK1/2 signaling pathway in a variety of hematopoietic cells, thereby lowering cytokine/chemokine levels in almost all MF patients, treatment with ruxolitinib did not affect PD-1 expression nor did it alter its distribution among the T cell subsets. Yet, the proportion of PD-1-expressing CD4+ and CD8+ cells was markedly reduced in patients who experienced a superior response to ruxolitinib as assessed by significant spleen size reduction. How disease burden and MF microenvironment affect PD-1 expression in T cells of patients with MF warrants further investigation. DisclosuresVerstovsek:Incyte: Consultancy; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Celgene: Membership on an entity's Board of Directors or advisory committees; Italfarmaco: Membership on an entity's Board of Directors or advisory committees.

Indication-specific immunomodulatory effects of extracorporeal photopheresis: A pilot study in heart transplanted patients.

The clinical use of extracorporeal photopheresis (ECP) is based on its ability to induce cell-mediated immune tolerance towards foreign and self-antigens. Up-to-date, no clear consensus consists on how to use ECP after heart transplantation (HTx). In this pilot study, we evaluated the stimulatory effects of ECP on immune cells in HTx patients. HTx patients received ECP therapy as prophylaxis of rejection (PRX, n = 15), to treat acute cellular rejection (ACR, n = 13) or cardiac allograft vasculopathy (CAV, n = 5). Three ECP cycles with monthly frequency were performed. Blood samples were taken before every ECP cycle and 2 months after the last ECP cycle and were analyzed for cytokines and the tolerance-inducing cell subsets regulatory T cells (Tregs ), myeloid (mDCs), and plasmacytoid dendritic cells (pDCs). While ECP treatment induced first an increase of pDCs in the CAV group (baseline: 22.0% ± 9.6%, prior third ECP cycle: 8.6% ± 3.2%, follow-up: 31.5% ± 8.4%, P = .009), no significant changes of DC subsets and Tregs were observed in the ACR- and in the PRX group. Furthermore, analysis of the immune balance showed different response profiles of pro- and anti-inflammatory cytokines among prophylactically ECP-treated patients and ECP-treated patients suffering from CAV or ACR. In our pilot study, we showed different stimulatory effects of ECP on pDCs and cytokines among prophylactic and therapeutic ECP therapy after HTx. Immunological monitoring should be included in a larger clinical study of ECP treatment following HTx and to identify predictable parameters for ECP efficacy.

Experimental study of glioma stem cell-mediated immune tolerance in tumor microenvironment

Objective: To investigate the tumor microenvironment of immune tolerance induced by glioma stem cells (GSC). Methods: Human GSC SU3 cells transfected with red fluorescent protein (SU3-RFP) gene were implanted into the brain, subcutis (armpit and foot), liver and abdominal cavity of transgenic green fluorescence protein (GFP) nude mice to establish RFP(+) /GFP(+) dual fluorescence solid tumor model. The re-cultured cells derived from implanted tumor tissues, SU3-RFP cells co-cultured with peritoneal fluid of transgenic GFP nude mice and malignant ascites of tumor-bearing mice were observed by fluorescence microscopy and real-time video image tracing to analyze the microenvironment of immune tolerance mediated by RFP(+) /GFP(+) implanted tumor. Results: Dual fluorescence labeled frozen section showed that all of cells in the tumor microenvironment were GFP(+) , while the pressed tissue-patch showed that the tumor blood vessels exhibited a RFP(+) /GFP(+) double-positioning yellow. In the GFP single fluorescence labeled tumor tissue, all of cells in the microenvironment were green, including tumor edge, necrotic foci and blood vessel. Among them, CD68(+) , F4/80(+) , CD11c(+) , CD11b(+) and CD80(+) cells were observed. In the dual fluorescence labeled co-cultured cells, the phagocytosis and fusion between green host cells and red tumor cells were also observed, and these fusion cells might transfer to the malignant dendritic cells and macrophages. Conclusions: The tumor microenvironment of immune tolerance induced by GSC is not affected by the tissue types of tumor-inoculated sites, and the immune tolerance mediated by inflammatory cells is associated with the inducible malignant transformation, which may be driven by cell fusion.

LPS-treated bone marrow-derived dendritic cells induce immune tolerance through modulating differentiation of CD4+ regulatory T cell subpopulations mediated by 3G11 and CD127.

Intravenous transfer of LPS-treated bone marrow-derived dendritic cells blocks development of autoimmunity induced by CD4+ T cells in vivo. However, cellular mechanisms of dendritic cell-mediated immune tolerance have not yet been fully elucidated. Here, we report that there are two new subpopulations of CD4+CD25+FoxP3+GITR+ regulatory T cells (CD127+3G11+ and CD127+3G11- cells). LPS-treated dendritic cells facilitate development of CD4+CD127+3G11- regulatory T cells but inhibit that of CD4+CD127+3G11+ regulatory T cells. LPS-induced tolerogenic dendritic cells may cause immune tolerance through modulating balance of different subsets of CD4+ regulatory T cells mediated by CD127 and 3G11. Our results imply a new potential cellular mechanism of dendritic cell-mediated immune tolerance.

Apoptotic cell-treated dendritic cells induce immune tolerance by specifically inhibiting development of CD4⁺ effector memory T cells.

CD4(+) memory T cells play an important role in induction of autoimmunity and chronic inflammatory responses; however, regulatory mechanisms of CD4(+) memory T cell-mediated inflammatory responses are poorly understood. Here we show that apoptotic cell-treated dendritic cells inhibit development and differentiation of CD4(+) effector memory T cells in vitro and in vivo. Simultaneously, intravenous transfer of apoptotic T cell-induced tolerogenic dendritic cells can block development of experimental autoimmune encephalomyelitis (EAE), an inflammatory disease of the central nervous system in C57 BL/6J mouse. Our results imply that it is effector memory CD4(+) T cells, not central memory CD4(+) T cells, which play a major role in chronic inflammatory responses in mice with EAE. Intravenous transfer of tolerogenic dendritic cells induced by apoptotic T cells leads to immune tolerance by specifically blocking development of CD4(+) effector memory T cells compared with results of EAE control mice. These results reveal a new mechanism of apoptotic cell-treated dendritic cell-mediated immune tolerance in vivo.

Apoptotic cell-treated dendritic cells induce immune tolerance through specifically facilitating development of CD4+ effector memory T cells (IRC10P.408)

Abstract CD4+ memory T cells play an important role in induction of autoimmunity and chronic inflammatory responses. However, regulatory mechanisms of CD4+ memory T cell-mediated inflammatory responses are poorly understood. Here we showed that apoptotic cell-treated dendritic cells inhibit development and differentiation of CD4+ effector and central memory T cells in vitro and in vivo. Simultaneously, i.v. transfer of apoptotic T cell-induced tolerogenic dendritic cells can block development of experimental autoimmune encephalomyelitis (EAE), an inflammatory disease in central nervous system of C57BL/6J mouse. However, our results imply that it is effector memory CD4+ T cells, not central memory CD4+ T cells which play a major role in chronic inflammatory responses in mice with EAE. I.v. transfer of tolerogenic dendritic cells induced by apoptotic T cells leads to immune tolerance through specifically blocking development of CD4+ effector memory T cells compared with results of EAE control mice. Our results reveal a new mechanism of apoptotic cell-treated dendritic cell-mediated immune tolerance in vivo.

Immune tolerance induction using fetal directed placental injection in rodent models: a murine model.

ObjectivesInduction of the immune response is a major problem in replacement therapies for inherited protein deficiencies. Tolerance created in utero can facilitate postnatal treatment. In this study, we aimed to induce immune tolerance towards a foreign protein with early gestational cell transplantation into the chorionic villi under ultrasound guidance in the murine model.MethodsPregnant C57BL/6 (B6) mice on day 10 of gestation were anesthetized and imaged by high resolution ultrasound. Murine embryos and their placenta were positioned to get a clear view in B-mode with power mode of the labyrinth, which is the equivalent of chorionic villi in the human. Bone marrow cells (BMCs) from B6-Green Fluorescence Protein (B6GFP) transgenic mice were injected into the fetal side of the placenta which includes the labyrinth with glass microcapillary pipettes. Each fetal mouse received 2 x 105 viable GFP-BMCs. After birth, we evaluated the humoral and cell-mediated immune response against GFP.ResultsBone marrow transfer into fetal side of placenta efficiently distributed donor cells to the fetal mice. The survival rate of this procedure was 13.5%(5 out of 37). Successful engraftment of the B6-GFP donor skin grafts was observed in all recipient (5 out of 5) mice 6 weeks after birth. Induction of anti-GFP antibodies was completely inhibited. Cytotoxic immune reactivity of thymic cells against cells harboring GFP was suppressed by ELISPOT assay.ConclusionsIn this study, we utilized early gestational placental injection targeting the murine fetus, to transfer donor cells carrying a foreign protein into the fetal circulation. This approach is sufficient to induce both humoral and cell-mediated immune tolerance against the foreign protein.

Liver inflammation abrogates T cell mediated tolerance against particulate antigens induced by liver Kupffer cells

Liver Kupffer cells are key players in the upkeep of body homeostasis, ingesting apoptotic material, gut derived microbiota and particulate antigens from the circulation. We investigated the immunoregulatory capacities of liver phagocytes in healthy and inflamed conditions against particle bound antigens addressing T cell mediated immune tolerance.

T cell immune abnormalities in immune thrombocytopenia.

Immune thrombocytopenia is an autoimmune disease with abnormal T cell immunity. Cytotoxic T cells, abnormal T regulatory cells, helper T cell imbalance, megakaryocyte maturation abnormalities and abnormal T cell anergy are involved in the pathogenesis of this condition. The loss of T cell-mediated immune tolerance to platelet auto-antigens plays a crucial role in immune thrombocytopenia. The induction of T cell tolerance is an important mechanism by which the pathogenesis and treatment of immune thrombocytopenia can be studied. Studies regarding the roles of the new inducible costimulator signal transduction pathway, the ubiquitin proteasome pathway, and the nuclear factor kappa B signal transduction pathway in the induction of T cell tolerance can help improve our understanding of immune theory and may provide a new theoretical basis for studying the pathogenesis and treatment of immune thrombocytopenia.