Interleukin-5 (IL-5) Therapy Prevents Allograft Rejection by Promoting CD4+CD25+ Ts2 Regulatory Cells That Are Antigen-Specific and Express IL-5 Receptor

CD4+CD25+Foxp3+T cell population is heterogenous and contains three major sub-groups. First, thymus derived T regulatory cells (tTreg) that are naïve/resting. Second, activated/memory Treg that are produced by activation of tTreg by antigen and cytokines. Third, effector lineage CD4+CD25+T cells generated from CD4+CD25- T cells’ activation by antigen to transiently express CD25 and Foxp3. We have shown that freshly isolated CD4+CD25+T cells are activated by specific alloantigen and IL-4, not IL-2, to Ts2 cells that express the IL-5 receptor alpha. Ts2 cells are more potent than naïve/resting tTreg in suppressing specific alloimmunity. Here, we showed rIL-5 promoted further activation of Ts2 cells to Th2-like Treg, that expressed foxp3, irf4, gata3 and il5. In vivo, we studied the effects of rIL-5 treatment on Lewis heart allograft survival in F344 rats. Host CD4+CD25+T cells were assessed by FACS, in mixed lymphocyte culture and by RT-PCR to examine mRNA of Ts2 or Th2-like Treg markers. rIL-5 treatment given 7 days after transplantation reduced the severity of rejection and all grafts survived ≥60d whereas sham treated rats fully rejected by day 31 (p<0.01). Treatment with anti-CD25 or anti-IL-4 monoclonal antibody abolished the benefits of treatment with rIL-5 and accelerated rejection. After 10d treatment with rIL-5, hosts’ CD4+CD25+ cells expressed more Il5ra and responded to specific donor Lewis but not self. Enriched CD4+CD25+ cells from rIL-5 treated rats with allografts surviving >60 days proliferated to specific donor only when rIL-5 was present and did not proliferate to self or third party. These cells had more mRNA for molecules expressed by Th2-like Treg including Irf4, gata3 and Il5. These findings were consistent with IL-5 treatment preventing rejection by activation of Ts2 cells and Th2-like Treg.

POS0673 TOLEROGENIC DENDRITIC CELLS IN RHEUMATOID ARTHRITIS PATIENTS: NEWS AND PROMISES

Background:Dendritic cells (DCs) are known to contribute to the pathogenesis of rheumatoid arthritis (RA) through presentation of cartilage glycoprotein, production of proinflammatory cytokines and activation of Th1/Th17 responses. Along with stimulating activity, DCs may exhibit suppressive functions via capacity to induce T cell apoptosis/anergy and to generate regulatory T cells. Since these DCs have potential to control autoreactive T-lymphocytes, the enhancing of tolerogenic properties of DCs seems to be a new important strategy in treatment of RA. Dexamethasone is widely used in clinical practice and can be used as a tolerogenic substance. Therefore, the properties of DCs generated in presence of dexamethasone are of great clinical interests.Objectives:The aim of our study is to describe the properties of tolerogenic DCs, generated with dexamethasone in patients with RA and their influence on autologous T-cells.Methods:Sixty five patients with RA with high and moderate activity of disease were recruited in this study. All patients follow ACR/EULAR criteria (2010). All studies were performed after receiving informed consent. All patients received conventional synthetic DMARDs. DCs were generated from blood monocytes culturing for 5 days with GM-CSF and IFN-α in the presence dexamethasone (dexDCS), applied on third day. LPS as maturation stimuli was added on fourth day. The expression of CD14, CD83, HLA-DR, TLR-2 on the surface of DCs was measured by flow cytometry. The functions of DCs were evaluated by measuring cytokine production and DCs allostimulatory activity in mixed lymphocyte culture. Mature DCs generated in absence of dexamethasone used as control.Results:We revealed that dexDCs are characterized by enhanced expression of CD14+cells and decreased number of CD83+cells but percent of HLA-DR+cells were constant (about 85). DexDCs show high expression of TLR-2 is seen as tolerogenic molecule (75%vs51%, p=0.05 compared to control). DexDCs also have marked prominent increase of TNFα/IL-10 ratio in contrast to control (0.59 vs 1.8, p=0.03). DexDCs suppressed proliferation of allogenic T-cells (2005 vs 7980 cpm, p=0.0002). To assess the stability of the DC in the proinfflamatory micro-environment after assessing stimulatory activity dexDCs were then cultivated with LPS and allostimulatory activity were evaluated one more. The stimulation activity dexDCs after incubation with LPS were not increase (4692 vs 6053 cpm, p=0.7). Also earlier we showed possibility of dexDCs induse apoptosis of autologous T-cells, activation of CD4+IL10+Tr1 and possession of antigen-specific suppression.Conclusion:The data obtained indicate that dexDCs from RA patients have the main tolerogenic features and stable in inflammatory environment that proves their potential in the treatment of rheumatoid arthritis.Disclosure of Interests:None declared

miR-223-3p Inhibits Antigen Endocytosis and Presentation and Promotes the Tolerogenic Potential of Dendritic Cells through Targeting Mannose Receptor Signaling and Rhob

Background. The role of miR-223-3p in dendritic cells (DCs) is unknown. This study is aimed at investigating the effect of miR-223-3p on the antigen uptake and presentation capacities of DCs and the underlying molecular mechanism. Methods. FITC-OVA antigen uptake and cell surface markers in bone marrow-derived DCs (BMDCs) were analyzed by flow cytometry. BMDCs were transfected with the miR-223-3p mimic or inhibitor. Cytokine levels were determined by ELISA. CD4+ T cell differentiation was determined by mixed lymphocyte culture assay. Results. OVA treatment significantly downregulated miR-223-3p in BMDCs. The miR-223-3p mimic significantly inhibited OVA-induced antigen uptake and surface expression of MHC-II on BMDCs (P<0.01). The miR-223-3p mimic increased TGF-β1 production in OVA-treated DCs (P<0.01). Mixed lymphocyte reaction showed that the miR-223-3p mimic significantly promoted Treg cell differentiation. In addition, the miR-223-3p mimic significantly upregulated CD103 in DCs, indicating the promotion of tolerogenic DCs. The miR-223-3p mimic downregulated Rhob protein in OVA-induced DCs. Rhob knockdown significantly suppressed the ability of FITC-OVA endocytosis (P<0.01) and surface MHC-II molecule expression (P<0.01) in BMDCs, promoting promoted Treg cell differentiation. Mannose receptor (MR) knockdown significantly upregulated miR-223-3p, downregulated Rhob protein in OVA-treated DCs, inhibited the FITC-OVA endocytosis and surface MHC-II expression in BMDCs, and promoted Treg cell differentiation (all P<0.01). Conclusion. These data suggest that miR-223-3p has an inhibitory effect on the antigen uptake and presentation capacities of BMDCs and promotes Treg cell differentiation, which is, at least partially, through targeting MR signaling and Rhob.

EFFECTS OF FEMALE BLOOD AUTOSERUM ON ALLOGENIC INTERACTIONS IN SHORT-TERM LYMPHOCYTE CULTURES OF PARENTS HAVING CHILDREN WITH CONOTRUNCAL HEART MALFORMATIONS

Highlights The findings of this original study ensure the detection of violations in the humoral regulation of the maternal immune interactions with semiallogeneic fetus, considered as a risk factor for developing sporadic conotruncal heart malformations in the next generation.Aim To study the role of female autoserum blood in limiting allogeneic interactions in short-term lymphocyte cultures of parents having children with conotruncal heart malformations.Methods 21 married couples (the study group) with children suffering from conotrucnal heart malformations (Tetralogy of Fallot) without chromosomal diseases were examined. The control group consisted of 21 families with three or more healthy children. The immune response in a mixed lymphocyte culture of parents was assessed by the increase in HLA-DR expression in the mixed culture with respect to spontaneous lymphocyte cultures. Primary staining of female and male lymphocytes with monoclonal antibodies to CD45, conjugated with various fluorescent dyes (PC-5 and PC-7), allowed assessing the immune response of female lymphocytes to male and vice versa.Results The effects of female autoserum on the mixed lymphocyte culture of parents were assessed. The obtained results reported that the birth of children with conotruncal heart malformations is associated with the interfering effect of female autoserum on HLA-DR expression on subpopulations of female lymphocytes (CD3+, HLA-DR+) and the activating effect on subpopulations of female lymphocytes (CD3-, HLA-DR+). The observed role of female autoserum in the study group may be associated with the absence of HLA-DR-blocking autoantibodies and high synthesis of cytokines by T2 and T3 helper lymphocytes.Conclusion The effects of female autoserum on allogeneic lymphocyte interactions of parents may be observed in short-term mixed lymphocyte cultures. The evaluation of the activating and interfering effects ensures timely identification of any violations in the humoral regulation of the maternal immune interactions with the HLA semiallogenic fetus, considered as a risk factor for developing sporadic conotruncal heart malformations in the next generation.

Angiotensin II Regulates Dendritic Cells through Activation of NF-κB /p65, ERK1/2 and STAT1 Pathways

Background: Activation of dendritic cells (DCs) is necessary to initiate immune responses. Angiotensin II (Ang II) has been reported to have a proinflammatory and immunomodulatory function. However, the role of Ang II in regulation of DCs and the underlying mechanisms remain illdefined. Methods: The effects of Ang II on the proliferation, maturation, phagocytosis, migration, and communication with T cells of DCs were analysed utilizing MTT, flow cytometry, ELISA, transwell assay and mixed lymphocyte culture. Results: We found that Ang II treatment significantly inhibited proliferation and phagocytic activity of DCs, but promoted the DC maturation and migration well as the expression of pro-inflammatory cytokines by DCs. In addition, Ang II also stimulated DC-mediated T cell proliferation. These effects were associated with activation of p65/NF-κB, ERK1/2 and STAT1 signaling pathways in DCs. Conclusions: Our results demonstrate that Ang II activates DCs partially through p65/NF-κB, ERK1/2 and STAT1 pathways, and suggest a potential therapeutic target of DC-mediated inflammatory disorders.

Glycolytic Inhibitor 3-Brpa Inhibits Proliferation and Induces Apoptosis of Mouse Splenic Lymphocytes in Mixed Lymphocytes Culture

Background: T-cell activation plays a critical role in the pathogenesis of acute graft-versus-host disease (GVHD). Quiescent T cells utilize oxidative phosphorylation to generate ATP, whereas activated T cells utilize glycolysis, so use glycolysis inhibitor may be a metabolically regulator needed to control T cells induced GVHD. The mixed lymphocytes culture (MLC) was used as a model to evaluate the effect of treatment for GVHD in vitro. Glucolysis inhibitor 3-Bromopyruvic acid (3-BrPA), a glucolysis inhibitor, can effectively induce multidrug resistance leukemia cell lines apoptosis and enhanced chemotherapy-induced cytotoxity to leukemia cells. Objective : This study aimed to study the effects of glycolytic inhibitor 3-Bromopyruvate (3-BrPA) on the proliferation, the apoptosis, the T lymphocyte subsets and the contents of cytokine IL-4 and IFN-γ in mouse spleen cells harvested from mixed lymphocyte culture. Methods An one-way mixed lymphocyte culture system characterized by labeled responder cells with BALB/c mouse spleen cells (H-2kd) and stimulator cells with C57BL/6 mouse spleen cells (H-2kb) was established. With treatment of 3-BrPA at different concentrations (0-200 μmol/L), the CCK-8 method was applied for lymphoproliferation activity, flow cytometry for cell surface markers of CD3, CD4 and CD8, and ELISA method for the levels of cytokine IL-4 and IFN-γ in the supernatant. Results: The CCK-8 test revealed that 3-BrPA in middle or high concentrations (over IC 30, 20 μmol/L) displayed a dose-dependent inhibitory effect on T-cell proliferation of MLC system. The IC50 were 48.6、41.2 and 41.9 μmol/L after 24 h, 36 h and 48 h of culture, respectively. FCM test discovered that the inhibitory effect mainly occurred in the CD4+ cells. After 48 h of culture, the apoptosis rate of 0, 10, 20, 50 and 100 μmol/L group were 4.86±0.88%, 5.2±1.13%, 12.63±2.97%, 18.55±4.06% and 22.47±3.61%, respectively. With treatment of 20 or 50μmol/L 3-BrPA, the levels of IFN-γ decreased obviously to 243.37±15.64 ng/L and 164.25±20.14 ng/L, compared with the control group (277.61±18.46 ng/L). The levels of IL-4 increased mildly to 33.18±5.69 ng/L and 31.06±6.06 ng/L, compared with the control group (28.64±3.97ng/L). Thus, the IFN-γ/IL-4 ratio decreased significantly. Conclusions :The results indicated that 3-BrPA could inhibit T cells proliferation, induce apoptosis and contribute to the Th2 cytokine environment in murine mixed lymphocyte culture system. Disclosures Liu: National Natural Science Foundation of China (81270647, 81300445, 81200388): Research Funding; National High Technology Research and Development Program of China (863 Program) (2011AA020105): Research Funding; National Public Health Grand Research Foundation (201202017): Research Funding; Natural Science Foundation of Guangdong Province (S2012010009299): Research Funding; the project of health collaborative innovation of Guangzhou city (201400000003-4, 201400000003-1): Research Funding; the Technology Plan of Guangdong Province of China (2012B031800403): Research Funding; the project of the Zhujiang Science & Technology Star of Guangzhou city (2013027): Research Funding.