Gut microbes enlarged the protective effect of transplanted regulatory B cells on rejection of cardiac allografts.

BACKGROUND: Regulatory B cells (Bregs) play an important role in maintaining immune homeostasis and have the potential to induce tolerance. Previous work has found that Breg cells are involved in heart transplantation tolerance. However, the effect of Breg on the transplantation tolerance and the underlying mechanisms remain to be clarified. METHODS: Using a within-species heart transplantation model, we aimed to investigate the role of CD19+CD5+CD1dhigh Bregs isolated from transplanted mice in preventing transplant rejection in vivo. We also explored the effects of CD40 and tumor necrosis factor receptor-associated factor 6 (TRAF6) ubiquitin ligase on Breg-mediated prolongation of survival in heart transplant (HT) mice, and the regulatory effects of downstream Cdk4 and Cdk6 proteins on dendritic cells (DCs), which clarified the function and molecular mechanism of Breg cells in HT mice. RESULTS: Our data suggest that adoptive transfer of the transplanted Bregs served as an effective tolerance-inducing mechanism in HT mice and was involved in the CD40-TRAF6 signaling pathway in DCs. Moreover, DCs collected from the Breg treated HT mice also prolonged the survival of HT mice. Furthermore, DC-specific knockout of TRAF6 diminished Breg-mediated prolongation of survival in HT mice. Interestingly, gut microbes from donors increased the survival of cardiac allografts both in both the absence and presence of Bregs but were not implicated in CD40-TRAF6 signaling. CONCLUSIONS: These findings reveal a role of Breg cells in the induction of transplantation tolerance through the blockade of the CD40-TRAF6 signaling pathway, which might be used in the treatment of HT in the clinic.

Diagnostic performance of quantitative and qualitative parameters for the diagnosis of aortic graft infection using [18F]-FDG PET/CT.

PURPOSE: The aim of this study was the evaluation of quantitative and qualitative parameters for the diagnosis of aortic graft infection (AGI) using [18F]-FDG PET/CT. METHODS: PET/CT was performed in 50 patients with clinically suspected AGI. 12 oncological patients with aortic repair but without suspicion of AGI were included in the analysis to serve as control cohort. The [18F]-FDG uptake pattern around the graft was assessed using (a) a five-point visual grading scale (VGS), (b) SUVmax and (c) different graft-to-background ratios (GBRs). The diagnostic performance of VGS, SUVmax and GBRs was assessed and compared by ROC analysis. RESULTS: 28 infected and 34 uninfected grafts were identified by standard of reference. SUVmax and VGS were the most powerful predictors for the diagnosis of AGI according to the area under the curve (AUC 0.988 and 0.983, respectively) without a significant difference compared to GBRs. SUVmax and VGS showed congruent and accurate findings in 54 patients (i.e. either both positive or negative), yielding sensitivity and specificity (100%) in this subgroup of patients. CONCLUSION: Quantitative analysis by SUVmax and qualitative analysis by VGS are highly effective in the diagnosis of AGI and should be tested as an outcome measure in prospective trials.

Myeloid-derived suppressor cells in transplantation tolerance induction.

Myeloid-derived suppressor cells (MDSCs) are a group of heterogeneous cells derived from bone marrow. These cells are developed from immature myeloid cells and have strong negative immunomodulatory effects. In the context of pathology (such as tumor, autoimmune disease, trauma, and burns), MDSCs accumulate around tumor and inflammatory tissues, where their main role is to inhibit the function of effector T cells and promote the recruitment of regulatory T cells. MDSCs can be used in organ transplantation to regulate the immune responses that participate in rejection of the transplanted organ. This effect is achieved by increasing the production of MDSCs in vivo or transfusion of MDSCs induced in vitro to establish immune tolerance and prolong the survival of the graft. In this review, we discuss the efficacy of MDSCs in a variety of transplantation studies as well as the induction of immune tolerance to prevent transplant rejection through the use of common clinical immunosuppressants combined with MDSCs.

Macrochimerism and clinical transplant tolerance.

Current theory holds that macrochimerism is essential to the development of transplant tolerance. Hematopoietic cell transplantation from the solid organ donor is necessary to achieve macrochimerism. Over the last 10-20 years, trials of tolerance induction with combined kidney and hematopoietic cell transplantation have moved from the preclinical to the clinical arena. The achievement of macrochimerism in the clinical setting is challenging, and potentially toxic due to the conditioning regimen necessary to hematopoietic cell transplantation and due to the risk of graft-versus-host disease. There are differences in chimerism goals and methods of the three major clinical stage tolerance induction strategies in both HLA-matched and HLA-mismatched living donor kidney transplantation, with consequent differences in efficacy and safety. The Stanford protocol has proven efficacious in the induction of tolerance in HLA-matched kidney transplantation, allowing cessation of immunosuppressive drug therapy in 80% of study participants, with the safety profile of conventional transplantation. In HLA-mismatched transplantation, multi-lineage macrochimerism of over a year's duration can now be consistently achieved with the Stanford protocol, with complete withdrawal of immunosuppressive drug therapy during the second post-transplant year as the next experimental step and test of tolerance.

MicroRNA 26a prolongs skin allograft survival and promotes regulatory T cell expansion in mice.

MicroRNA 26a (Mir-26a) has been reported to play functions in cellular differentiation, cell growth, cell apoptosis, and metastasis. However, the role of Mir-26a in transplant rejection has never been investigated. Full-thickness skin grafts 1-2 cm in diameter were obtained from the tail-skin CBA/J donor mice and transplanted onto the back of wild-type C57Bl/6 recipient mice. Vectors encoding pre-Mir-26a (LV-26a) and an empty lentiviral vector (LV-Con) delivered approximately 2 × 10(7) transforming units of recombinant lentivirus were injected to mice once through the tail vein. Mir-26a overexpression results in prolonged skin allograft survival (MST = 9.5 days in LV-Con mice; MST = 22 days in LV-26a mice. P < 0.01) and promoted regulatory T cells (Tregs) expansion. The prolonged skin allograft survival induced by LV-26a was abrogated by depletion of Tregs with anti-CD25 antibodies. Mir-26a significantly promoted IL-10 expression and suppressed the expression of IL-6, IL-17, and IFN-γ. Furthermore, IL-6 overexpression led to complete suppression of the Mir-26a-induced upregulation of Foxp3. The prolonged allograft survival induced by LV-Mir-26a was also completely abrogated by IL-6 overexpression. In conclusion, Mir-26a prolongs skin allograft survival and promotes Tregs expansion in part through inhibition of IL-6 expression.

Kidney-induced cardiac allograft tolerance in miniature swine is dependent on MHC-matching of donor cardiac and renal parenchyma.

Kidney allografts possess the ability to enable a short course of immunosuppression to induce tolerance of themselves and of cardiac allografts across a full-MHC barrier in miniature swine. However, the renal element(s) responsible for kidney-induced cardiac allograft tolerance (KICAT) are unknown. Here we investigated whether MHC disparities between parenchyma versus hematopoietic-derived "passenger" cells of the heart and kidney allografts affected KICAT. Heart and kidney allografts were co-transplanted into MHC-mismatched recipients treated with high-dose tacrolimus for 12 days. Group 1 animals (n = 3) received kidney and heart allografts fully MHC-mismatched to each other and to the recipient. Group 2 animals (n = 3) received kidney and heart allografts MHC-matched to each other but MHC-mismatched to the recipient. Group 3 animals (n = 3) received chimeric kidney allografts whose parenchyma was MHC-mismatched to the donor heart. Group 4 animals (n = 3) received chimeric kidney allografts whose passenger leukocytes were MHC-mismatched to the donor heart. Five of six heart allografts in Groups 1 and 3 rejected <40 days. In contrast, heart allografts in Groups 2 and 4 survived >150 days without rejection (p < 0.05). These data demonstrate that KICAT requires MHC-matching between kidney allograft parenchyma and heart allografts, suggesting that cells intrinsic to the kidney enable cardiac allograft tolerance.

Circulating biomarkers of tolerance.

On the basis of reviewed literature here we describe models of tolerance and summarize the evidence of circulating biomarkers suitable for the assessment of immunological risk in organ transplantation. We focused on results of evaluation of specific peripheral immune cell populations and transcripts in peripheral blood of operationally tolerant liver and kidney transplant recipients. Validation of described markers to define potentially tolerant patients before their use in clinical trials is critical.

Proteomic analysis in serum of rat hind-limb allograft tolerance induced by immunosuppressive therapy with adipose-derived stem cells.

BACKGROUND: Adipose-derived stem cells combined with transient immunosuppression prolonged vascularized composite tissue allotransplant survival and induced immune tolerance in a rodent hind-limb model. The authors investigated serum proteins in the adipose-derived stem cell tolerance group and control group using proteomic study. METHODS: An orthotopic hind-limb model from Brown-Norway to Lewis rats was used. The control group received no treatment. Rats in the tolerance group received combined treatments of short-term cyclosporine A, antilymphocyte serum, and multiple rounds of adipose-derived stem cells. Serum samples were analyzed. Spots of interest were subjected to in-gel trypsin digestion and matrix-assisted laser desorption ionization time-of-flight mass spectrometry to elucidate the peptide mass fingerprints. The mass spectrometric characteristics of the identified proteins were analyzed. Immunohistochemical analysis of transplanted tissue and enzyme-linked immunosorbent assay of serum were validated. RESULTS: Rats in the tolerance group had significantly higher amounts of ß2-glycoprotein, α1-macroglobulin, rat-albumin, and vitamin D-binding protein, and significantly lower levels of haptoglobin compared with controls. Immunohistochemical staining of the alloskin indicated similar effects, such as up-regulated vitamin D-binding protein and down-regulated haptoglobin in the tolerance group compared with rejection controls (p < 0.05). Enzyme-linked immunosorbent assay revealed that vitamin D-binding protein was statistically increased (p < 0.05) and haptoglobin expression was significantly decreased (p < 0.01) in the tolerance group compared with the controls. CONCLUSIONS: There were significant differences in the serum proteomics between the tolerance and control groups. Down-regulated haptoglobin and up-regulated vitamin D-binding protein are involved in adipose-derived stem cell-induced immune tolerance and allotransplant survival.

Stable mixed hematopoietic chimerism permits tolerance of vascularized composite allografts across a full major histocompatibility mismatch in swine.

This study tested the hypothesis that vascularized composite allografts (VCA) could be accepted in a robust model of hematopoietic chimerism by injecting allogeneic bone marrow cells (BMC) into swine fetuses. Outbred Yorkshire sows and boars were screened to ensure the absence of the major histocompatibility (MHC) allele SLA(cc) of inbred MGH miniature swine and then mated. Bone marrow harvested from an SLA(cc) swine donor was T-cell depleted and injected intravenously into the fetuses between days 50-55 of gestation. After birth, the piglets were studied with flow cytometry to detect donor cells and mixed lymphocyte reactions (MLR) and cell-mediated lympholysis (CML) assays to assess their response to donor. Donor-matched VCAs from SLA(cc) donors were performed on four chimeric and two nonchimeric swine. The results showed donor cell engraftment and multilineage macrochimerism after the in utero transplantation of adult BMC, and chimeric animals were unresponsive to donor antigens in vitro. Both control VCAs were rejected by 21 days and were alloreactive. Chimeric animals accepted the VCAs and never developed antidonor antibodies or alloreactivity to donor. These results confirm that the intravascular, in utero transplantation of adult BMC leads to donor cell chimerism and donor-specific tolerance of VCAs across a full MHC barrier in this animal model.

Comparación de resultados entre el retrasplante y el trasplante renal primario en el Hospital Hermanos Ameijeiras de 1984 a 2012 / Comparison of results between retransplantation and primary kidney transplantation on Hermanos Ameijeiras Hospital from 1984 to 2012

Introducción: el retrasplante constituye la mejor opción terapéutica para los enfermos que pierden un primer trasplante renal y vuelven a diálisis, existen disímiles criterios en cuanto a sus resultados al compararlos con los trasplantes renales primarios. Objetivo: analizar el porcentaje de retrasplantes, revisar la supervivencia del injerto y del enfermo, el comportamiento de variables que pueden incidir en los resultados y compararlos con los de los enfermos que reciben un primer trasplante renal. Métodos: se realizó un estudio analítico, descriptivo, retrospectivo, de los trasplante renales realizados en el Hospital Hermanos Ameijeiras desde 1984 hasta diciembre de 2012; quedaron excluidos, los terceros trasplante, dobles (2 riñones a un mismo receptor), combinados (páncreas-riñón e hígado-riñón) y aquellos en los que no fue posible obtener la información requerida para la investigación. Se compararon (entre los grupos retrasplantes y primeros trasplantes) variables de índole general: edad de los receptores y donantes, sexo del receptor, enfermedad que ocasionó la insuficiencia renal, porcentaje de reactividad ante un panel de linfocito (PRA), compatibilidades HLA, tipo de donante (vivo o cadáver), tiempos de isquemia, presencia y duración de necrosis tubular aguda (donante cadáver), rechazo y supervivencia del injerto y el paciente. Resultados: los retrasplantes constituyeron el 5,4 por ciento de la muestra. No existieron diferencias entre edades, sexo, PRA, compatibilidades ni tipo de donante entre los segundos y primeros injertos. Los enfermos que llegaron a la insuficiencia renal por riñones poliquísticos nunca han recibido en nuestro centro un segundo trasplante. Resultó significativamente estadístico el uso de terapia cuádruple secuencial como inmunosupresión de inducción en los retrasplantes (55,9 por ciento vs. 9,7 por ciento de los primarios...

Introduction: retransplant constitutes the best therapeutic choice for patients who lose a first renal transplant and return to dialysis, existing dissimilar criteria as to its results when ranking them with renal primary transplant. Objective: to analyze the percentage of retransplantation, to revise graft and patient survival, to review the behavior of variables that can affect the results and to compare them with patients receiving a first renal transplant. Methods: an analytic, descriptive, retrospective study was accomplished, including all renal transplant performed at the Hermanos Ameijeiras Hospital from 1984 to December of 2012. Third transplants, double transplants (two kidneys to the same receptor), combined transplants (pancreas-kidney and liver-kidney) and those where it was not possible to obtain the information required for this research were excluded. Variables of general nature were compared between retransplantation groups and first transplants, such as: age of recipient and donor, sex of the recipient, a disease that caused kidney failure, percentage of reactivity to a lymphocyte panel (PRA), HLA compatibility, donor type (living or dead), ischemia time, presence and duration of acute tubular necrosis (dead donor), rejection and graft and patient survival. Results:rRetransplant constituted only 5.4 percent of the sample (34 patients). There were no differences in age, sex, PRA, donor type or compatibilities between the second and first grafts. Patients who reached the renal failure due to polycystic kidneys have never had a second transplant in our institution. The use of sequential quadruple therapy as induction immunosuppression, retransplantation (55.9 percent vs. 9.7 percent of primary) was statistically significant...

Heart transplantation: challenges facing the field.

There has been significant progress in the field of heart transplantation over the last 45 years. The 1-yr survival rates following heart transplantation have improved from 30% in the 1970s to almost 90% in the 2000s. However, there has been little change in long-term outcomes. This is mainly due to chronic rejection, malignancy, and the detrimental side effects of chronic immunosuppression. In addition, over the last decade, new challenges have arisen such as increasingly complicated recipients and antibody-mediated rejection. Most, if not all, of these obstacles to long-term survival could be prevented or ameliorated by the induction of transplant tolerance wherein the recipient's immune system is persuaded not to mount a damaging immune response against donor antigens, thus eliminating the need for chronic immunosuppression. However, the heart, as opposed to other allografts like kidneys, appears to be a tolerance-resistant organ. Understanding why organs like kidneys and livers are prone to tolerance induction, whereas others like hearts and lungs are tolerance-resistant, could aid in our attempts to achieve long-term, immunosuppression-free survival in human heart transplant recipients. It could also advance the field of pig-to-human xenotransplantation, which, if successful, would eliminate the organ shortage problem. Of course, there are alternative futures to the field of heart transplantation that may include the application of total mechanical support, stem cells, or bioengineered whole organs. Which modality will be the first to reach the ultimate goal of achieving unlimited, long-term, circulatory support with minimal risk to longevity or lifestyle is unknown, but significant progress in being made in each of these areas.

The purinergic system in allotransplantation.

The purine nucleotide adenosine triphosphate (ATP) is a universal source of energy for any intracellular reaction. Under specific physiological or pathological conditions, ATP can be released into extracellular spaces, where it binds and activates the purinergic receptors system (i.e. P2X, P2Y and P1 receptors). Extracellular ATP (eATP) binds to P2X or P2Y receptors in immune cells, where it mediates proliferation, chemotaxis, cytokine release, antigen presentation and cytotoxicity. eATP is then hydrolyzed by ectonucleotidases into adenosine diphosphate (ADP), which activates P2Y receptors. Ectonucleotidases also hydrolyze ADP to adenosine monophosphate and adenosine, which binds P1 receptors. In contrast to P2X and P2Y receptors, P1 receptors exert mainly an inhibitory effect on the immune response. In transplantation, a prominent role has been demonstrated for the eATP/P2X7R axis; the targeting of this pathway in fact is associated with long-term graft function and reduced graft versus host disease severity in murine models. Novel P2X receptor inhibitors are available for clinical use and are under assessment as immunomodulatory agents. In this review, we will focus on the relevance of the purinergic system and on the potential benefits of targeting this system in allograft rejection and tolerance.

[Proteasomes on thyroid tissue allotransplantation under induction of donor specific tolerance in rats].

The proteasomes in the liver of August rats (RT1C) were investigated 30 days after the allotransplantation of Wistar rat (RT1u) thyroid tissue under renal capsule with/without induction of donor specific tolerance by donor splenocyte intraportal administration. The level of the total proteasome pool, immune proteasomes containing the LMP2 and/or LMP7 subunits, proteasome 19S- and 11S-regulators was defined. The intact and sham-operated August rats were used as control groups. The level of all immune proteasome forms and 11S regulator increased while the level of the total proteasome pool and 19S regulator decreased in the liver of experimental animals compared to the control groups that indicated changes of liver functional state after transplantation. The 19S/11S ratio increased in the liver of non-tolerated rats compared to tolerated animals. In the liver of tolerated rats with survived transplants, the quantity of mononuclear cells, expressing the immune subunit LMP2, greatly increased in comparison with control and non-tolerated animals. Study of the survived transplants showed the increase of the ratio of LMP2/LMP7 immune subunits and 19S/11S regulators in them compared to the tissue replacing the rejected transplants. In the control intact thyroid tissue, the immune proteasomes were almost not revealed, while 19S/11S ratio was maximal. Thus, the development of the immune reaction or its suppression is accompanied by change of the balance between different proteasome forms. The immune subunit LMP7 and 11S regulator are connected with the response against donor tissue. On the contrary, the immune subunit LMP2 and 19S regulator are likely to be important for the immune tolerance development and survived tissue functioning. The low content of the immune proteasomes in the follicle cells was found by immunofluorescence assay. The formation of antigens for major histocompatibility complex class I molecules was impaired by low immune proteasome content that led to immunological tolerance to hormone-producing follicle cells.

Membrane-bound human SCF/KL promotes in vivo human hematopoietic engraftment and myeloid differentiation.

In recent years, advances in the humanized mouse system have led to significantly increased levels of human hematopoietic stem cell (HSC) engraftment. The remaining limitations in human HSC engraftment and function include lymphoid-skewed differentiation and inefficient myeloid development in the recipients. Limited human HSC function may partially be attributed to the inability of the host mouse microenvironment to provide sufficient support to human hematopoiesis. To address this problem, we created membrane-bound human stem cell factor (SCF)/KIT ligand (KL)-expressing NOD/SCID/IL2rgKO (hSCF Tg NSG) mice. hSCF Tg NSG recipients of human HSCs showed higher levels of both human CD45(+) cell engraftment and human CD45(+)CD33(+) myeloid development compared with NSG recipients. Expression of hSCF/hKL accelerated the differentiation of the human granulocyte lineage cells in the recipient bone marrow. Human mast cells were identified in bone marrow, spleen, and gastrointestinal tissues of the hSCF Tg NSG recipients. This novel in vivo humanized mouse model demonstrates the essential role of membrane-bound hSCF in human myeloid development. Moreover, the hSCF Tg NSG humanized recipients may facilitate investigation of in vivo differentiation, migration, function, and pathology of human mast cells.

Engraftment of human HSCs in nonirradiated newborn NOD-scid IL2rγ null mice is enhanced by transgenic expression of membrane-bound human SCF.

Immunodeficient mice engrafted with human HSCs support multidisciplinary translational experimentation, including the study of human hematopoiesis. Heightened levels of human HSC engraftment are observed in immunodeficient mice expressing mutations in the IL2-receptor common γ chain (IL2rg) gene, including NOD-scid IL2rγ(null) (NSG) mice. Engraftment of human HSC requires preconditioning of immunodeficient recipients, usually with irradiation. Such preconditioning increases the expression of stem cell factor (SCF), which is critical for HSC engraftment, proliferation, and survival. We hypothesized that transgenic expression of human membrane-bound stem cell factor Tg(hu-mSCF)] would increase levels of human HSC engraftment in nonirradiated NSG mice and eliminate complications associated with irradiation. Surprisingly, detectable levels of human CD45(+) cell chimerism were observed after transplantation of cord blood-derived human HSCs into nonirradiated adult as well as newborn NSG mice. However, transgenic expression of human mSCF enabled heightened levels of human hematopoietic cell chimerism in the absence of irradiation. Moreover, nonirradiated NSG-Tg(hu-mSCF) mice engrafted as newborns with human HSCs rejected human skin grafts from a histoincompatible donor, indicating the development of a functional human immune system. These data provide a new immunodeficient mouse model that does not require irradiation preconditioning for human HSC engraftment and immune system development.

Tolerance in clinical transplantation: progress, challenge or just a dream?

INTRODUCTION: The achievement of clinical operational tolerance (COT) is still considered a major goal in the academic field of solid organ transplantation. Even COT is feasible and safe in selected cases after liver transplantation, in the clinical arena of solid organ transplantation, tolerance remains, for the most part, a concept rather than a reality. CHALLENGES: Although modern immunosuppression regimens have effectively handled acute rejection, nearly all organs except the liver commonly suffer chronic immunologic damage that impairs organ function, threatening patient and allograft survival. Strong arguments in favour of conducting clinical tolerance trials are the high number of grafts still lost due to chronic rejection, the burden of serious adverse effects from immunosuppressants which causes considerable cardiovascular morbidity and mortality, respectively, and the fact that sporadic tolerance can be observed in rare cases where non-adherence to immunosuppressive regimens is linked with a state of long-lasting organ tolerance. Whereas molecule-based regimens have been largely ineffective, cell-based tolerance protocols have delivered some encouraging results to achieve COT. DISCUSSION: In combination with donor bone marrow-derived stem cells, some encouraging results in COT development were reported lately for renal transplantation as well. However, less toxic conditioning protocols and more experience by use of cell products with regulatory properties in combination with synergizing immunosuppressive drugs is required to launch future tolerance trials for a broader spectrum of potential transplant candidates. New methods in immunomonitoring including biomarkers, microarray-based genetic tolerance signatures and functional assays may pave the way to achieve COT in upcoming clinical trials.

Mast cell protease 6 is required for allograft tolerance.

It has been shown that mast cells (MC) are absolutely required for transplant acceptance. However, only a few of the numerous mediators produced by MC have been proposed as potential mechanisms for the observed immunosuppression. The role of proteases in acquired immune tolerance as such has not yet been addressed. In this study, we have shown the requirement for MC protease 6 (MCP6), an MC-specific tryptase, to establish tolerance toward an allogeneic skin graft. The substrate for MCP6 is interleukin (IL)-6, cytokine generally considered to indicate transplant rejection. Herein we have shown an inverse correlation between MCP6 and IL-6. High expression of MCP6 is accompanied by low levels of IL-6 when the allograft is accepted, whereas low expression of MCP6 in combination with high levels of IL-6 are observed in rejecting grafts. Moreover, tolerance toward an allogeneic graft cannot be induced in MCP6(-/-) mice. Rejection observed in these mice was comparable to that of MC-deficient hosts; it is T-cell mediated. These findings suggest that MCP6 actively depletes the local environment of IL-6 to maintain tolerance.

[Tracheal allotransplantation after withdrawal of immunosuppressive therapy]. / La création d'une transplantation trachéale vascularisée.

Reconstruction of long-segment tracheal defects requires a vascularized allograft. We report successful tracheal allotransplantation after indirect revascularization of the graft in a heterotopic position. Immunosuppressive therapy was administered before the operation, and the tracheal allograft was wrapped in the recipient's forearm fascia. Once revascularization was achieved, the mucosal lining was replaced progressively with buccal mucosa from the recipient. At 4 months, the tracheal chimera was fully lined with mucosa, which consisted of respiratory epithelium from the donor and buccal mucosa from the recipient. After withdrawal of immunosuppressive therapy, the tracheal allograft was moved to its correct anatomical position with an intact blood supply. No treatment-limiting adverse effects occurred.

Indoleamine 2,3-dioxygenase in lung allograft tolerance.

BACKGROUND: Indoleamine 2,3-dioxygenase (IDO), an enzyme involved in the degradation of tryptophan (Try) to kynurenine (Kyn), is thought to suppress T-cell activity. Although a few experimental studies have suggested a role for IDO in graft acceptance, human data are scarce and inconclusive. We sought to establish whether, in lung transplant recipients (LTRs), plasma IDO activity mirrors the level of graft acceptance. METHODS: We measured the plasma Kyn/Try ratio, reflecting IDO activity, by high-performance liquid chromatography (HPLC) in 90 LTRs, including 26 patients who were still functionally/clinically stable for >36 post-transplant months (stable LTRs) and 64 LTRs with bronchiolitis obliterans syndrome (BOS, Grades 0-p to 3). Twenty-four normal healthy controls (NHCs) were also included. RESULTS: The Kyn/Try ratio in stable LTRs resembled that observed in NHCs, whereas, unexpectedly, patients with BOS, who had lower counts of peripheral CD4(+) T-regulatory cells and tolerogenic plasmacytoid dendritic cells than stable LTRs, showed an increased plasma Kyn/Try ratio compared with both NHCs and stable LTRs. IDO expression by in vitro-stimulated peripheral blood mononuclear cells (PBMC) did not vary between BOS and stable LTRs. Furthermore, BOS patients displayed signs of chronic systemic inflammation (increased plasma levels of interleukin-8 and tumor necrosis factor-alpha) and higher T-cell activation (increased frequency of peripheral interferon-gamma-producing clones). CONCLUSIONS: Our results suggest that, in vivo, in lung transplantation, plasma IDO activity does not reflect the degree of lung graft acceptance, but instead is correlated with the degree of chronic inflammation.

Gene transfer of calcitonin gene-related peptide suppresses development of allograft vasculopathy.

OBJECTIVE: To explore suppression of allograft vasculopathy by transfer of the calcitonin gene-related peptide (CGRP). METHODS: The descending thoracic aortas from Lewis rats were grafted to the abdominal aortas of F344 rats, and the rats were randomized into 2 groups. A gene construct containing sequences from the adenoviral oncoprotein, the CGRP, and the enhanced green fluorescent protein was transferred into 1 group, and the sequences for the adenoviral oncoprotein and enhanced green fluorescent protein were transferred into a control group. Specimens were harvested at 4 and 8 weeks. Gene transfer was confirmed at fluorescence microscopy of frozen tissue sections, and expression was measured using reverse transcriptase-polymerase chain reaction. We determined the locations and levels of vascular cell adhesion molecule-1 (VCAM-1) and inducible nitric oxide synthase (iNOS) at immunohistochemistry and measured apoptosis. RESULTS: The CGRP gene was expressed only in the CGRP group at 4 weeks. The vascular luminal occlusion score in the CGRP group was lower than in the control group. The apoptotic index of the CGRP group was lower than in the control group only at 4 weeks. The VCAM-1 immunohistochemistry score in the CGRP group was lower than in the control group; however, the iNOS immunohistochemistry score in the CGRP group was lower than in the control group in the intima only at 4 weeks. CONCLUSION: The expression of CGRP effectively suppressed the development of allograft vasculopathy and encroachment by lymphocytes and inflammatory cells. This reduced the levels of VCAM-1 to inhibit apoptosis induced by iNOS; thus, the tissue of the allografted vessel was protected and rejection was averted.