Cardiac Transplantation Model Research Articles

Notch-1 Inhibition Promotes Immune Regulation in Transplantation Via Regulatory T Cell-Dependent Mechanisms.

Transplantation is the treatment of choice for many patients with end-stage organ disease. Despite advances in immunosuppression, long-term outcomes remain suboptimal, hampered by drug toxicity and immune-mediated injury, the leading cause of late graft loss. The development of therapies that promote regulation while suppressing effector immunity is imperative to improve graft survival and minimize conventional immunosuppression. Notch signaling is a highly conserved pathway pivotal to T-cell differentiation and function, rendering it a target of interest in efforts to manipulate T cell-mediated immunity. We investigated the pattern of Notch-1 expression in effector and regulatory T cells (Tregs) in both murine and human recipients of a solid-organ transplant. Using a selective human anti-Notch-1 antibody (aNotch-1), we examined the effect of Notch-1 receptor inhibition in full major histocompatibility complex-mismatch murine cardiac and lung transplant models, and in a humanized skin transplant model. On the basis of our findings, we further used a genetic approach to investigate the effect of selective Notch-1 inhibition in Tregs. We observed an increased proportion of Tregs expressing surface and intracellular (activated) Notch-1 in comparison with conventional T cells, both in mice with transplants and in the peripheral blood of patients with transplants. In the murine cardiac transplant model, peritransplant administration of aNotch-1 (days 0, 2, 4, 6, 8, and 10) significantly prolonged allograft survival in comparison with immunoglobulin G-treated controls. Similarly, aNotch-1 treatment improved both histological and functional outcomes in the murine lung transplant model. The use of aNotch-1 resulted in a reduced proportion of both splenic and intragraft conventional T cells, while increasing the proportion of Tregs. Furthermore, Tregs isolated from aNotch-1-treated mice showed enhanced suppressive function on a per-cell basis, confirmed with selective Notch-1 deletion in Tregs (Foxp3EGFPCreNotch1fl/fl). Notch-1 blockade inhibited the mammalian target of rapamycin pathway and increased the phosphorylation of STAT5 (signal transducer and activator of transcription 5) in murine Tregs. Notch-1low Tregs isolated from human peripheral blood exhibited more potent suppressive capacity than Notch-1high Tregs. Last, the combination of aNotch-1 with costimulation blockade induced long-term tolerance in a cardiac transplant model, and this tolerance was dependent on CTLA-4 (cytotoxic T-lymphocyte-associated antigen-4) signaling. Our data reveal a promising, clinically relevant approach for immune modulation in transplantation by selectively targeting Notch-1.

Foxp3 cooperates with Ikaros to control the suppressive function of regulatory T cells

Abstract Ikaros (encoded by Ikzf1) is a lymphocyte-specific transcription factor that controls a wide spectrum of T cell functions, including T helper differentiation, cytokine production, and tolerance in response to antigenic stimuli. Using heterozygous and dominant-negative mouse models, we have shown previously that Ikaros controls IL-2 production by conventional T cells, T helper differentiation, CD8+ effector differentiation, and anergy induction. While the role of Ikaros in many T cell subsets has been established, its role in Treg-mediated peripheral tolerance has not been examined. To examine the Treg-specific role of Ikaros, we generated Ikzf1-fl/fl-Foxp3-YFP-Cre+ mouse with conditional deletion of Ikaros in Tregs. Ikzf1-fl/fl-Foxp3-YFP-Cre+ mouse exhibited enlarged secondary lymphoid tissues, with increased frequencies of effector memory Tconv and Treg. We show that Ikaros expression by Tregs is required for immune tolerance in an allogenic cardiac transplant model. While CD28- and CD40L-blockade induced long-term cardiac allograft tolerance in control recipients, Ikzf1-fl/fl-Foxp3-YFP-Cre+ recipients rejected the allografts in a short duration (p<0.01). We show that Ikaros forms a complex with Foxp3, which is required for Foxp3 to bind to and repress inflammatory cytokine genes. Ikaros is also required for normal iTreg development in vitro, as TGF-B/IL-2-induced iTreg development is impaired in conventional CD4+ T cells with reduced Ikaros activity. These studies suggest that Ikaros interacts with Foxp3 and directs Foxp3 to exert its suppressive function in Tregs.

Toll-like receptor 2 deficiency promotes the generation of alloreactive Th17 cells after cardiac transplantation in mice

The emergence of alloreactive Th17 cells that mediate allograft rejection has provided an impetus to understand the factors affecting the generation of Th17 cells in allograft transplantation. How toll-like receptor 2 (TLR2) signalling regulates the generation of Th17 cells upon alloantigen stimuli remains unclear. In this study, we used a mouse model of cardiac allograft transplantation to investigate whether TLR2 signalling influences the development of Th17 cells. Here, we demonstrate that the TLR2-deficient recipient mice show high Th17 cells, both in spleens and allografts, as well as higher infiltrating inflammatory leukocytes in cardiac allografts compared to wild-type control recipient mice. mRNA expression of IL-17, IL-6, TNF-α, CCR6 and CCL20 within the allografts is markedly increased in TLR2-deficient recipient mice compared to wild-type recipient mice. In addition, TLR2 deficiency leads to upregulation of Signal transducer and activator of transcription 3 (STAT3) phosphorylation in both spleens and allografts. In an in vitro experiment, a mixed lymphocyte reaction was assessed, which further confirmed that TLR2 deficiency leads to a significant increase in the generation of Th17 cells compared with wild-type controls. Furthermore, IL-6 secreted by the dendritic cells of TLR2-deficient mice contributes to driving the generation of these Th17 cells. These results suggest that TLR2 signalling is important in regulating the development of Th17 cells after cardiac allograft transplantation.

Effect of the Selective NLRP3 Inflammasome Inhibitor mcc950 on Transplantation Outcome in a Pig Liver Transplantation Model With Organs From Donors After Circulatory Death Preserved by Hypothermic Machine Perfusion.

We investigated whether the outcome of organs from donors after circulatory death (DCD) can be improved by the addition of mcc950 to the perfusate of the hypothermic machine perfusion (HMP) system and intravenous mcc950 injection after transplantation in a pig liver transplantation model. Thirty-six healthy Bama mini pigs randomized into 3 groups. All the DCD livers were preserved in an HMP system after 2 hours of simple cold storage. In HMP-Postop group, mcc950 was added to the perfusate; in the control group and Postop group, the perfusate was normal LPS. After transplantation, the pigs in the Postop group and HMP-Postop group were intravenously administered 3 mg/kg mcc950, at the time of reperfusion and on day 2 and day 3 after transplantation. During the 3-day follow-up period, general operative characteristics, and serological markers and histological features related to ischemia reperfusion injury were examined. The HMP-Postop group suffer the lightest ischemia reperfusion injury (IRI), and functioned best after transplantation. Model for the Early Allograft Function Score (predictor of long-term survival), degree of injury in the hepatocytes and rate of apoptosis was lowest in the HMP-Postop group. Further, in the HMP-Postop group, the nucleotide-binding domain leucine-rich repeat containing family pyrin domain containing 3 inflammasome pathway activation was lowest, and the level of IL-1β was lowest. Postop group functioned better than control group, but not comparable with HMP-Postop group. The outcome of DCD organs can be improved by the addition of mcc950 to the perfusate of the HMP system and intravenous injection of mcc950 after transplantation.

The Role of Secretory Leukocyte Proteinase Inhibitor During Transplantation

Old and new players of the innate immune response have been studied in the context of transplantation. Nonetheless, little interest has been focused toward the immune regulatory feedback in transplantation. Here, we revised the role of secretory leukocyte proteinase inhibitor (SLPI), which limits the activity of serine proteases, in solid organ transplantation. Ischemia-reperfusion injury increases SLPI gene expression. Furthermore, post-transplant acute kidney injury increases the expression of SLPI transcript and protein. Several studies have shown that SLPI exerts direct, indirect, and locally mediated beneficial effects in multiple ischemia-reperfusion models. Moreover, the addition of SLPI in the preservation solution improved cardiac performance in a cardiac transplantation model. Diverse factors present at the time of transplantation facilitate the production and secretion of SLPI, which in turn acts as a feedback mechanism to control graft injury. The pleiotropic activity of SLPI as a tolerogenic factor, as well as microbicidal and wound healing agent, should motivate the exploration of its utility as an adjuvant therapeutic tool in transplanted patients. Further studies are also required to analyze the utility of SLPI as a biomarker of graft quality and injury.

A novel 2,4-diaminopyrimidine derivative as selective inhibitor of protein kinase C theta prevents allograft rejection in a rat heart transplant model

Protein kinase C theta (PKCθ) plays a critical role in T cell signaling and is an attractive target for the treatment of T cell-mediated diseases such as transplant rejection and autoimmune disease. To identify PKCθ inhibitors, we focused on the 2,6-diamino-3-carbamoyl-5-cyanopyrazine derivative 2, which exhibited moderate PKCθ inhibitory activity. Optimization of 2 identified the 2,4-diamino-5-cyanopyrimidine derivative 16c, which exhibited potent PKCθ inhibitory activity and showed good selectivity against other PKC isozymes. Compound 16c prolonged graft survival in an in vivo rat heterotopic cardiac transplant model.

Effective suppression of donor specific antibody production by Cathepsin S inhibitors in a mouse transplantation model

Donor-specific antibodies (DSA) are a major risk factor for antibody-mediated rejection (ABMR) in solid organ transplantation, and ABMR remains a medical challenge. Therefore, effective anti-ABMR therapies are needed to improve overall graft survival. Cathepsin S (Cat S) is an essential protease for antigen peptide loading onto lysosomal/endosomal major histocompatibility complex (MHC) class II molecules to promote antigen presentation. Cat S deficiency produces immuno-deficient phenotypes including a suppressed humoral immune response, and Cat S inhibition reportedly prevents autoimmunity. However, little is known about the effects of Cat S inhibitors on organ transplantation, especially ABMR. Here, we report the pharmacological profile of novel Cat S inhibitors, AS2761325 and AS2863995, and explore their preventive potential on DSA production and acute rejection in a mouse cardiac transplantation model. Cat S inhibitors potently inhibited upregulation of antigen peptide loading MHC class II expression on the surface of splenic B cells and suppressed ovalbumin-induced T cell-dependent antibody production in mice. In a mouse cardiac transplantation model, oral administration of AS2761325 monotherapy inhibited DSA production without affecting graft survival. When combined with a suboptimal dose of tacrolimus, AS2761325 significantly prolonged graft survival. The more potent Cat S inhibitor AS2863995 also prolonged graft survival and almost completely suppressed DSA production. These results suggest that Cat S inhibitors may be promising ABMR prophylaxis drug candidates. Combination therapy comprising a Cat S inhibitor and calcineurin inhibitors may be a more effective immunosuppressive maintenance therapy for controlling both cell-mediated and antibody-mediated rejection.

The need for dedicated advanced heart failure units to optimize heart failure care: impact of optimized advanced heart failure unit care on heart transplant outcome in high-risk patients.

AimWith an increasing prevalence of heart failure (HF), more patients with advanced disease have to be treated in cardiology units by sophisticated medical and interventional strategies. We therefore developed a dedicated advanced heart failure unit (AHFU) to target the specific needs of the many patients with advanced HF. We here present our concept and its impact on outcome in high‐risk high‐urgency (HU) heart transplant candidates.Methods and resultsThe eight‐bed unit was established as an extension of the cardiologic intensive care and coronary care units in an intermediate care setting. Each bed was equipped with 24 h haemodynamic, respiratory, and arrhythmia monitoring. The unit is served 24/7 by five residents in cardiology, one staff cardiologist specializing in medical and interventional HF care, and 10 intensive care nurses. The cardiology team is supported by colleagues from cardiac surgery, sports medicine, psychosomatics, and the internal medicine departments. As an example of the intensified care on the AHFU, data from the cohorts of patients undergoing heart transplantation from HU status before (pre‐AHFU 2008–11) and after establishment of the AHFU (AHFU 2012–15) were analysed. Interestingly, mortality on HU waiting list and post‐heart transplant survival was comparable in both cohorts, despite significant increase in morbidity and co‐morbidity as assessed by the Index for Mortality Prediction After Cardiac Transplantation model in the AHFU group.ConclusionsOur AHFU provides a unique and novel setting for the integration of modern pharmacological, interventional, surgical, and supportive HF therapy embedded in an academic heart centre. This may be a major step forward in the care of critical patients with advanced HF.

IL23R is a Pathogenic Gene in Type 1 Regulatory T cells During Mouse Cardiac Transplantation Models

IL23R is a Pathogenic Gene in Type 1 Regulatory T cells During Mouse Cardiac Transplantation Models

Adoptive Transfer of HVEM signal induced Alloreacitve Regulatory T cell Protect Rejection in Allogeneic Murine Cardiac Transplantation Model.

Background Donor antigen specific immunosuppression is ideal strategy in organ transplantation to decrease the risk of life-long immunosuppression. Material and Method Donor reactive FOXP3 + regulatory T cell were generated from hCD2-FOXP3 reporter C57BL/6 background mouse splenocyte with pre-coated HVEM agonistic mAb and irradiated donor splenocyte and purified by magnetic sorting. This donor reactive regulatory T cell were cocultured with naïve splenocyte stimulated by donor antigen and adoptively transfer into transplanted mouse to evaluate their protection for graft rejection. Results The HVEM induced alloreavitve hCD2+ regulatory T cell suppress anti-donor response more than non-treated alloreactive hCD2+ regulatory nor naïve hCD2+ regulatory T cell. Graft survival was significantly prolonged in the cell therapy group compared with allogeneic transplants ( Log Rank p<0.05).Conclusion HVEM agonistic signal enhance suppressive function in FOXP3+ alloreacitve regulatory T cells. This cell therapy might be option to protect graft rejection.

Equal Expansion of Endogenous Transplant-Specific Regulatory T Cell and Recruitment Into the Allograft During Rejection and Tolerance.

Despite numerous advances in the definition of a role for regulatory T cells (Tregs) in facilitating experimental transplantation tolerance, and ongoing clinical trials for Treg-based therapies, critical issues related to the optimum dosage, antigen-specificity, and Treg-friendly adjunct immunosuppressants remain incompletely resolved. In this study, we used a tractable approach of MHC tetramers and flow cytometry to define the fate of conventional (Tconvs) and Tregs CD4+ T cells that recognize donor 2W antigens presented by I-Ab on donor and recipient antigen-presenting cells (APCs) in a mouse cardiac allograft transplant model. Our study shows that these endogenous, donor-reactive Tregs comparably accumulate in the spleens of recipients undergoing acute rejection or exhibiting costimulation blockade-induced tolerance. Importantly, this expansion was not detected when analyzing bulk splenic Tregs. Systemically, the distinguishing feature between tolerance and rejection was the inhibition of donor-reactive conventional T cell (Tconv) expansion in tolerance, translating into increased percentages of splenic FoxP3+ Tregs within the 2W:I-Ab CD4+ T cell subset compared to rejection (~35 vs. <5% in tolerance vs. rejection). We further observed that continuous administration of rapamycin, cyclosporine A, or CTLA4-Ig did not facilitate donor-specific Treg expansion, while all three drugs inhibited Tconv expansion. Finally, donor-specific Tregs accumulated comparably in rejecting tolerant allografts, whereas tolerant grafts harbored <10% of the donor-specific Tconv numbers observed in rejecting allografts. Thus, ~80% of 2W:I-Ab CD4+ T cells in tolerant allografts expressed FoxP3+ compared to ≤10% in rejecting allografts. A similar, albeit lesser, enrichment was observed with bulk graft-infiltrating CD4+ cells, where ~30% were FoxP3+ in tolerant allografts, compared to ≤10% in rejecting allografts. Finally, we assessed that the phenotype of 2W:I-Ab Tregs and observed that the percentages of cells expressing neuropilin-1 and CD73 were significantly higher in tolerance compared to rejection, suggesting that these Tregs may be functionally distinct. Collectively, the analysis of donor-reactive, but not of bulk, Tconvs and Tregs reveal a systemic signature of tolerance that is stable and congruent with the signature within tolerant allografts. Our data also underscore the importance of limiting Tconv expansion for high donor-specific Tregs:Tconv ratios to be successfully attained in transplantation tolerance.

Everted Suturing of the Inferior Vena Cava Is Addressed in the Abdominal Mouse Heart Transplant Model.

Our objective was to investigate the techniques of vessel suturing in the abdominal mouse cardiac transplant model and animal outcomes. Our mouse group included 92 female inbred mice, in which 46 abdominal mouse heart transplants were performed. During transplant, the openings for the aorta and the inferior vena cava were not parallel. With everted anastomosis, the ascending aortae and the pulmonary arteries of donors were connected to the abdominal aortae and interior vena cavae of recipients, respectively, with 11-0 Prolene suture. We recorded complications and animal survival. The first 2 mice that underwent the procedure died of blood loss on day 1. However, the remaining 44 mouse recipients were alive for greater than 14 days, resulting in 14-day survival rate of 95.65%. Range of time to complete the whole procedure, including learning curve, was 47 to 72 minutes. At histology, implanted hearts from recipients with long-term survival appeared normal. The procedure for everted suturing in the abdominal mouse heart transplant model was easy to perform and had a high success rate.

Impact of Regulatory T Cells on Innate Immune Cells in a Pre-Sensitized Heart Transplant Model

BackgroundAlthough our previous studies revealed the role of Tregs (regulatory T cells) and MDSCs (myeloid-derived suppressor cells) in a pre-sensitized cardiac transplant model, interplay between Tregs and NK cells, neutrophils, and macrophages remain undefined.Material/MethodsMice heart transplantation with skin pre-sensitization was performed, in which prolonged-cold ischemia time (PCI) was used for donor treatment. Syngeneic heterotopic heart transplant recipients with PCI were treated with PC61 (monoclonal anti-CD25 antibodies), adoptive cell transfer with Tregs, and rapamycin.ResultsWe unveiled that both rapamycin treatment and adoptive transfer of Tregs could lead to a remarkable decrease of frequency of splenic Gr1+ cells (P=0.058 and P=0.016, respectively). Although administration of PC61 did not affect frequency of splenic Gr1+ cells, it dramatically increased frequency of splenic F4/80+ macrophages (P=0.052). Intriguingly, use of both exogenous PC61 and rapamycin induced a dramatic augmentation of frequency of Gr-1+ neutrophils in the grafts (PC61: P=0.00029; rapamycin: P=0.0096). Noticeably, all different regimens including PC61, rapamycin, and adoptive transfer of Tregs, consistently resulted in a remarked augmentation of frequency of F4/80+ macrophages within grafts (PC61, P=0.0013; rapamycin, P=0.015; Tregs transfer, P=0.013). Although rapamycin and adoptive transfer of Tregs did not affect frequency of NK1.1+ cells, administration of PC61 dramatically increased frequency of NK1.1+ cells within grafts (P=0.033).ConclusionsTregs depletion or Tregs induced by rapamycin or exogenous cell transfer could affect frequencies of both splenic and intragraft neutrophils, macrophages, and NK cells, but not splenic NK cells. Our data might shed light on understanding sensitized transplant biology.

Seven Japanese Herbals Prolonged Cardiac Allograft Survival

Japanese herbal medicines have long been used as alternative therapy because of their immunomodulatory effects. In recent years, use herbal medicines is rapidly increasing worldwide. In this study, we investigated the effect of 17 components of traditional Japanese herbal medicines on alloimmune responses in a murine model of cardiac allograft transplantation. Fully vascularized heterotopic hearts from C57BL/6 donors were transplanted into CBA mice by using microsurgical techniques. Artemisiae capillaris herba (Inchinko) was given to CBA recipients at a dosage of 1 g/kg/day from the day of transplantation until 7 days afterward. The other 16 components were given at a dosage of 2 g/kg/day for the same time period. Naïve CBA mice rejected C57BL/6 cardiac grafts acutely (median survival time [MST] of 7 days). CBA transplant recipients given 2 g/kg/day of Glycyrrhizae radix (Kanzou), Poria sclerotium (Bukuryo), Pinellia tuber (Hange), Cnidii rhizome (Senkyu), Paeoniae radix (Shakuyaku), and Scutellariae radix (Ogon) had prolonged C57BL/6 allograft survival significantly (MSTs were 18, 18, 17, 14, 12, and 12 days, respectively). Moreover, CBA transplant recipients given 1g/kg/day of Artemisiae capillaris herba had prolonged C57BL/6 allograft survival (MST >100 days); however, none of other 10 components prolonged allograft survival. In conclusion, administration of 7 components of traditional Japanese herbal medicines might induce prolongation of fully major histocompatibility complex–mismatched cardiac allografts.

Administration of Thrombomodulin (CD141) Could Improve Cardiac Allograft Survival in Mice

Thrombomodulin (TM) is a promising natural anti-coagulant therapeutic protein that is effective in the treatment of disseminated intravascular coagulation. However, the mechanisms by which TM on micro-vessels enable the regulation of intimal hyperplasia remain elusive. We investigated the graft-protective effects of TM in a fully major histocompatibility complex-mismatched murine cardiac allograft transplantation model. CBA recipients transplanted with a C57BL/6 heart received intraperitoneal administration of 0.2, 2.0, and 20.0 μg/day of TM for 8 days. Histological staining was conducted to assess the degree of inflammation and infiltration in the transplanted cardiac grafts. Untreated CBA recipients rejected C57BL/6 cardiac grafts acutely (median survival time [MST] was 7 days). CBA recipients exposed to the above dosages had significantly prolonged allograft survival (MSTs were 16, 21, and 37.5 days, respectively). Histologic assessments from TM-exposed recipients 2 weeks after grafting showed that the myocardium and vessel structure in their allografts were clearly preserved, and that the infiltration of inflammatory cells around coronary arteries was suppressed. TM can induce the prolongation of fully major histocompatibility complex-mismatched cardiac allograft by exerting graft protective effects within the myocardium and coronary arteries.

Rikkunshito (TJ-43) Improved Reduction of Food Intake in a Murine Cardiac Transplantation Model

Rikkunshito (TJ-43), an eight-component traditional Japanese herbal medicine, has been used in clinics for gastritis, vomiting, and appetite loss. We investigated the effects of TJ-43 on the amelioration of appetite loss in the surgical-exposed model of murine cardiac allograft transplantation. CBA mice underwent transplantation of a CBA (syngeneic group) or C57BL/6 heart (allogeneic group) and received oral administration of 2 g/kg/d of TJ-43 from the day of transplantation until 7 days afterward. The amount of food intake (FI) and weight change after operation were recorded from 1 to 28 postoperative days. The allogeneic group had less average amounts of FI for 1 week compared with the syngeneic group (FI was 1.90 ± 0.43 g and 2.66 ± 0.46 g, respectively). Average FIs between the syngeneic and allogeneic groups with TJ-43 for 1 week were 2.36 ± 0.44 g and 2.30 ± 0.13 g, respectively, and those with distilled water were 2.66 ± 0.46 g and 1.90 ± 0.43 g, respectively, suggesting that exposure with TJ-43 tended to ameliorate the reduction of FI. Similarly, the effect on the amelioration of average FI in syngeneic and allogeneic groups exposed for 2 weeks was confirmed. However, exposure to with TJ-43 had no effects on FI after 4 weeks. TJ-43 could prevent reduction of average FI induced by the surgical-exposed model of murine cardiac allograft transplantation.

Expression Pattern of Tumor Necrosis Factor-α–Induced Protein 8-Like 2 in Acute Rejection of Cardiac Allograft

BackgroundTumor necrosis factor-α–induced protein-8 like-2 (TIPE2) is a negative regulator of innate immunity and cellular immunity, yet the expression pattern of TIPE2 in acute rejection of cardiac allograft remain enigmatic. MethodsWe developed cardiac transplantation models and divided into 3 groups: a naive group, a syngeneic group, and an allogeneic group. Then, we detected the messenger RNA and protein of TIPE2 in cardiac allografts. Real-time polymerase chain reaction showed expression of CD4 and CD8 in the donor heart, and immunofluorescence assay revealed the association between T cells and TIPE2. ResultsIn our study, we first found that the expression of TIPE2 in cardiac allografts is upregulated compared with the syngeneic control, and increases in a time-dependent manner. The immunocytochemistry of heart grafts revealed a strong expression of TIPE2 in the inflammatory cells, but not in the cardiomyocytes. Finally, we proved that CD4+ and CD8+ T cells infiltrated cardiac allografts abundantly, which express ample TIPE2. ConclusionsThe upregulated expression of TIPE2 in cardiac allografts, mainly came from T cells, which infiltrated the donor heart. This finding indicates that there may be an association between TIPE2 and acute cardiac allograft rejection.

More adipose-derived mesenchymal stem cells more inhibition of the acute rejection in rat cardiac transplantation models

More adipose-derived mesenchymal stem cells more inhibition of the acute rejection in rat cardiac transplantation models

Inhibition of C-X-C motif chemokine 10 reduces graft loss mediated by memory CD8+ T cells in a rat cardiac re-transplant model.

The interaction of chemokine (C-X-C motif) ligand 10 (CXCL10) with its receptor (CXCR3) is a critical process in recruiting donor reactive T cells to a graft and alloantigen-specific memory T (Tm) cells exert a principal function in promoting graft dysfunction during accelerated cardiac rejection. However, whether CXCL10 chemokine exerts any effects on acute accelerated rejection mediated by CD8+ Tm cells in a re-transplant model has remained elusive. The present study established a cardiac transplant model by advanced microsurgery technology and improved organ storage. A novel rat model of cardiac re-transplantation was established at 40 days following primary heart transplant. The experiment included two parts, and when models were established, the rats were divided into two groups: Primary cardiac transplant (HTx) and re-transplantation without treatment (HRTx). In part 1, recipients from part 2, including re-transplantation without treatment (HRTx+NS) and re-transplantation treated with anti-CXCL10 antibodies (500 µg every other day by intraperitoneal injection; HRTx+CXCL10 Abs group). The graft survival time was observed and graft infiltration by inflammatory cells was assessed via histology of cardiac graft sections; in addition, the gene expression and the serum concentration of CXCL10 in each group was assessed. Indexes such as rejection-associated cytokines were assayed by reverse-transcription quantitative PCR and ELISA kits, and flow cytometry of splenocytes was used to detect Tm cells in the re-transplantation groups. The results demonstrated that level of CXCL10 was significantly increased and the graft mean survival time was shortened accompanied with aggravated lymphocyte cell infiltration in the HRTx group when compared that in the HTx group; in addition, the serum levels and mRNA expression of interleukin (IL)-2 and interferon (IFN)-γ were increased, while transforming growth factor (TGF)-β was decreased in the HRTx group. Furthermore, neutralization of CXCL10 prolonged the graft mean survival time and delayed accelerated rejection. Compared with that in the HRTx+NS group, serum levels and graft tissue mRNA expression of IFN-γ and IL-2 were decreased in the HRTx+CXCL10 Abs group, while TGF-β mRNA was significantly increased but the serum concentration was not significantly affected. In addition, there was no difference in IL-10 between the two groups, while delayed accelerated rejection paralleled with inflammatory cell infiltration decreased and the proliferation and differentiation of CD8+ Tm cells in secondary lymphoid organs were reduced in the HRTx+CXCL10 Abs group vs. those in the HRTx+NS group. The present study demonstrated that CXCL10 had a crucial role in cardiac transplantation and re-transplantation, and that treatment with CXCL10 antibodies delays accelerated acute rejection mediated by Tm cells in a rat model of cardiac re-transplantation.

Complete Genome Sequence of a Strain of Bifidobacterium pseudolongum Isolated from Mouse Feces and Associated with Improved Organ Transplant Outcome.

ABSTRACTHere, we report the complete genome sequence of Bifidobacterium pseudolongum strain UMB-MBP-01, isolated from the feces of C57BL/6J mice. This strain was identified in microbiome profiling studies and associated with improved transplant outcome in a murine model of cardiac heterotypic transplantation.