The role of CD8+ T cells during allograft rejection

Donor-specific antibodies against HLA-C, HLA-DP and HLA-DQ and their implications in kidney transplantation

HLA-C, HLA-DP and HLA-DQ are thought to be benign due to low expression and few initial negative studies. Historically, most allocation programs used HLA-A, HLA-B and HLA-DR antigens for matching. With the advent and use of single-bead antigen assays, more was learned about donor-specific antibodies (DSAs) against these antigens. Interest in these antigens and antibodies grew when cases of acute antibody-mediated rejection (AMR), mixed rejections, chronic AMR, and reduced graft survival were reported with DSAs against these antigens. Although the deleterious effects of these DSAs are more pronounced in retransplants, harmful effects have also been observed in first-time recipients. DSAs against each of these antigens can trigger rejection alone. Their combination with DSAs against HLA-A, HLA-B and HLA-DR can cause more damage. It has been shown that strategies that reduce mismatches for these antigen lead to fewer rejections and better graft survival. There is a need for greater consensus on the universal typing of these antigens prior to transplantation for better patient and graft outcomes. This review focuses on the interaction of these antigens with lymphocytes and killer immunoglobulin receptors, arguments for not typing them, detailed analyses of the literature about their harmful effects, potential strategies moving forward, and recommendations for the future.

Current Scenario and Future Perspectives of Porcine Corneal Xenotransplantation

ABSTRACT

Corneal diseases represent a significant cause of blindness worldwide, with corneal transplantation being an effective treatment to prevent vision loss. Despite substantial advances in transplantation techniques, the demand for donor corneas exceeds the available supply, particularly in developing countries. Cornea xenotransplantation has emerged as a promising strategy to address the worldwide scarcity, notably using porcine corneas. In addition to the inherent immune privilege of the cornea, the low cost of porcine breeding and the anatomical and physiological similarities between humans and pigs have made porcine corneas a viable alternative. Nonetheless, ethical concerns, specifically the risk of xenozoonotic transmission and the necessity for stringent biosafety measures, remain significant obstacles. Moreover, the success of xenotransplantation is compromised by innate and adaptive immune responses, which requires meticulous consideration and further studies. Despite these challenges, recent breakthroughs have further contributed to reducing immunogenicity while preserving the corneal architecture. Advances in genetic engineering, such as the use of CRISPR-Cas9 to eliminate critical porcine antigens, have shown promise for mitigating immune reactions. Additionally, new immunosuppressive protocols, such as have techniques like decellularization and the use of porcine-derived acellular matrices, have greatly increased graft survival in preclinical models. Future research must focus on refining immunomodulatory strategies and improving graft preparation techniques to ensure the long-term survival and safety of porcine corneal xenotransplantation in clinical trials in humans.

Immunological Landscapes in Lung Transplantation: Insights from T Cell Profiling in BAL and PBMC

Lung transplant recipients frequently encounter immune-related complications, including chronic lung allograft dysfunction (CLAD). Monitoring immune cells within the lung microenvironment is pivotal for optimizing post-transplant outcomes. This study examined the proportion of T cell subsets in paired bronchoalveolar lavage (BAL) and peripheral PBMC comparing healthy (n = 4) and lung transplantation patients (n = 6, no CLAD and n = 14 CLAD) using 14-color flow cytometry. CD4+ T cell proportions were reduced in CD3 cells in both PBMC and BAL, and positive correlations were discerned between T cell populations in peripheral PBMC and BAL, suggesting the prospect of employing less invasive PBMC sampling as a means of monitoring lung T cells. Furthermore, regulatory T cells (Tregs) were enriched in BAL when compared to peripheral PBMC for transplant recipients. A parallel positive correlation emerged between Treg proportions in BAL and peripheral PBMC, underscoring potential avenues for monitoring lung Tregs. Finally, the most promising biomarker was the Teff (CD8+Granzyme B+)-Treg ratio, which was higher in both the PBMC and BAL of transplant recipients compared to healthy individuals, and increased in the patients with CLAD compared to no CLAD and healthy patients. Conclusions: Distinct T cell profiles in BAL and peripheral PBMC underscore the significance of localized immune monitoring in lung transplantation. The Teff (CD8+granzyme B+)-Treg ratio, particularly within the context of CLAD, emerges as a promising blood and BAL biomarker reflective of inflammation and transplant-related complications. These findings emphasize the imperative need for personalized immune monitoring strategies that tailored to address the unique immunological milieu in post-transplant lungs.

Immunogenicity and tolerance induction in vascularized composite allotransplantation

Vascularized composite allotransplantation (VCA) is the transplantation of multiple tissues such as skin, muscle, bone, nerve, and vessels, as a functional unit (i.e., hand or face) to patients suffering from major tissue trauma and functional deficits. Though the surgical feasibility has been optimized, issues regarding graft rejection remains. VCA rejection involves a diverse population of cells but is primarily driven by both donor and recipient lymphocytes, antigen-presenting cells, macrophages, and other immune as well as donor-derived cells. In addition, it is commonly understood that different tissues within VCA, such as the skin, elicits a stronger rejection response. Currently, VCA recipients are required to follow potent and lifelong immunosuppressing regimens to maximize graft survival. This puts patients at risk for malignancies, opportunistic infections, and cancers, thereby posing a need for less perilous methods of inducing graft tolerance. This review will provide an overview of cell populations and mechanisms, specific tissue involved in VCA rejection, as well as an updated scope of current methods of tolerance induction.

Unique Changes in the Lung Microbiome following the Development of Chronic Lung Allograft Dysfunction

The importance of lung microbiome changes in developing chronic lung allograft dysfunction (CLAD) after lung transplantation is poorly understood. The lung microbiome-immune interaction may be critical in developing CLAD. In this context, examining alterations in the microbiome and immune cells of the lungs following CLAD, in comparison to the lung condition immediately after transplantation, can offer valuable insights. Four adult patients who underwent lung retransplantation between January 2019 and June 2020 were included in this study. Lung tissues were collected from the same four individuals at two different time points: at the time of the first transplant and at the time of the explantation of CLAD lungs at retransplantation due to CLAD. We analyzed whole-genome sequencing using the Kraken2 algorithm and quantified the cell fractionation from the bulk tissue gene expression profile for each lung tissue. Finally, we compared the differences in lung microbiome and immune cells between the lung tissues of these two time points. The median age of the recipients was 57 years, and most (75%) had undergone lung transplants for idiopathic pulmonary fibrosis. All patients were administered basiliximab for induction therapy and were maintained on three immunosuppressants. The median CLAD-free survival term was 693.5 days, and the median time to redo the lung transplant was 843.5 days. Bacterial diversity was significantly lower in the CLAD lungs than at transplantation. Bacterial diversity tended to decrease according to the severity of the CLAD. Aerococcus, Caldiericum, Croceibacter, Leptolyngbya, and Pulveribacter genera were uniquely identified in CLAD, whereas no taxa were identified in lungs at transplantation. In particular, six taxa, including Croceibacter atlanticus, Caldiserium exile, Dolichospermum compactum, Stappia sp. ES.058, Kinetoplastibacterium sorsogonicusi, and Pulveribacter suum were uniquely detected in CLAD. Among immune cells, CD8+ T cells were significantly increased, while neutrophils were decreased in the CLAD lung. In conclusion, unique changes in lung microbiome and immune cell composition were confirmed in lung tissue after CLAD compared to at transplantation.

Inhibition of Prostaglandin-Degrading Enzyme 15-PGDH Mitigates Acute Murine Lung Allograft Rejection

PURPOSE

Acute rejection is a frequent complication among lung transplant recipients and poses substantial therapeutic challenges. 15-hydroxyprostaglandin dehydrogenase (15-PGDH), an enzyme responsible for the inactivation of prostaglandin E2 (PGE2), has recently been implicated in inflammatory lung diseases. However, the role of 15-PGDH in lung transplantation rejection remains elusive. The present study was undertaken to examine the expression of 15-PGDH in rejected lung allografts and whether inhibition of 15-PGDH ameliorates acute lung allograft rejection.

METHODS

Orthotopic mouse lung transplantations were performed between donor and recipient mice of the same strain or allogeneic mismatched pairs. The expression of 15-PGDH in mouse lung grafts was measured. The efficacy of a selective 15-PGDH inhibitor (SW033291) in ameliorating acute rejection was assessed through histopathological examination, micro-CT imaging, and pulmonary function tests. Additionally, the mechanism underlying the effects of SW033291 treatment was explored using CD8+ T cells isolated from mouse lung allografts.

RESULTS

Increased 15-PGDH expression was observed in rejected allografts and allogeneic CD8+ T cells. Treatment with SW033291 led to an accumulation of PGE2, modulation of CD8+ T-cell responses and mitochondrial activity, and improved allograft function and survival.

CONCLUSION

Our study provides new insights into the role of 15-PGDH in acute lung rejection and highlights the therapeutic potential of inhibiting 15-PGDH for enhancing graft survival. The accumulation of PGE2 and modulation of CD8+ T-cell responses represent potential mechanisms underlying the benefits of 15-PGDH inhibition in this model. Our findings provide impetus for further exploring 15-PGDH as a target for improving lung transplantation outcomes.

An Immune Atlas of T Cells in Transplant Rejection: Pathways and Therapeutic Opportunities

Short-term outcomes in allotransplantation are excellent due to technical and pharmacological advances; however, improvement in long-term outcomes has been limited. Recurrent episodes of acute cellular rejection, a primarily T cell-mediated response to transplanted tissue, have been implicated in the development of chronic allograft dysfunction and loss. Although it is well established that acute cellular rejection is primarily a CD4 + and CD8 + T cell mediated response, significant heterogeneity exists within these cell compartments. During immune responses, naïve CD4 + T cells are activated and subsequently differentiate into specific T helper subsets under the influence of the local cytokine milieu. These subsets have distinct phenotypic and functional characteristics, with reported differences in their contribution to rejection responses specifically. Of particular relevance are the regulatory subsets and their potential to promote tolerance of allografts. Unraveling the specific contributions of these cell subsets in the context of transplantation is complex, but may reveal new avenues of therapeutic intervention for the prevention of rejection.

IL-10-Engineered Dendritic Cells Modulate Allogeneic CD8+ T Cell Responses

Tolerogenic dendritic cells (tolDC) play a central role in regulating immune homeostasis and in promoting peripheral tolerance. These features render tolDC a promising tool for cell-based approaches aimed at inducing tolerance in T-cell mediated diseases and in allogeneic transplantation. We developed a protocol to generate genetically engineered human tolDC overexpressing IL-10 (DCIL-10) by means of a bidirectional lentiviral vector (LV) encoding for IL-10. DCIL-10 promote allo-specific T regulatory type 1 (Tr1) cells, modulate allogeneic CD4+ T cell responses in vitro and in vivo, and are stable in a pro-inflammatory milieu. In the present study, we investigated the ability of DCIL-10 to modulate cytotoxic CD8+ T cell responses. We demonstrate that DCIL-10 reduces allogeneic CD8+ T cell proliferation and activation in primary mixed lymphocyte reactions (MLR). Moreover, long-term stimulation with DCIL-10 induces allo-specific anergic CD8+ T cells without signs of exhaustion. DCIL-10-primed CD8+ T cells display limited cytotoxic activity. These findings indicate that stable over-expression of IL-10 in human DC leads to a population of cells able to modulate cytotoxic allogeneic CD8+ T cell responses, overall indicating that DCIL-10 represent a promising cellular product for clinical applications aimed at inducing tolerance after transplantation.

Cytotoxic T Lymphocytes (CTLs) and Kidney Transplantation: An Overview

Involvement of T lymphocytes in kidney transplantation is a well-developed topic; however, most of the scientific interest focused on the different type of CD4+ lymphocyte subpopulations. Few authors, instead, investigated the role of CD8+ T cells in renal transplantation and how deleterious they can be to long-term allograft survival. Recently, there has been a renewed interest in the CD8+ T cells involvement in the transplantation field with the aim to investigate the immunological mechanisms underlying the infiltration of CD8+ T cells and their biological functions in human kidney allografts. The purpose of the present review is to highlight the role of allo-reactive cytotoxic T lymphocytes (CTLs) CD8⁺ subset in allograft kidney recipients and their related clinical complications.

Berberine Prolongs Mouse Heart Allograft Survival by Activating T Cell Apoptosis via the Mitochondrial Pathway

Berberine, which is a traditional Chinese medicine can inhibit tumorigenesis by inducing tumor cell apoptosis. However, the immunoregulatory of effects berberine on T cells remains poorly understood. Here, we first examined whether berberine can prolong allograft survival by regulating the recruitment and function of T cells. Using a major histocompatibility complex complete mismatch mouse heterotopic cardiac transplantation model, we found that the administration of moderate doses (5 mg/kg) of berberine significantly prolonged heart allograft survival to 19 days and elicited no obvious berberine-related toxicity. Compared to that with normal saline treatment, berberine treatment decreased alloreactive T cells in recipient splenocytes and lymph node cells. It also inhibited the activation, proliferation, and function of alloreactive T cells. Most importantly, berberine treatment protected myocardial cells by decreasing CD4⁺ and CD8⁺ T cell infiltration and by inhibiting T cell function in allografts. In vivo and in vitro assays revealed that berberine treatment eliminated alloreactive T lymphocytes via the mitochondrial apoptosis pathway, which was validated by transcriptome sequencing. Taken together, we demonstrated that berberine prolongs allograft survival by inducing apoptosis of alloreactive T cells. Thus, our study provides more evidence supporting the potential use of berberine in translational medicine.

Cross-presentation of dead-cell-associated antigens by DNGR-1+ dendritic cells contributes to chronic allograft rejection in mice

The purpose of this study was to elucidate whether DC NK lectin group receptor-1 (DNGR-1)-dependent cross-presentation of dead-cell-associated antigens occurs after transplantation and contributes to CD8⁺ T cell responses, chronic allograft rejection (CAR), and fibrosis. BALB/c or C57BL/6 hearts were heterotopically transplanted into WT, Clec9a^-/- , or Batf3^-/- recipient C57BL/6 mice. Allografts were analyzed for cell infiltration, CD8⁺ T cell activation, fibrogenesis, and CAR using immunohistochemistry, Western blot, qRT² -PCR, and flow cytometry. Allografts displayed infiltration by recipient DNGR-1⁺ DCs, signs of CAR, and fibrosis. Allografts in Clec9a^-/- recipients showed reduced CAR (p < 0.0001), fibrosis (P = 0.0137), CD8⁺ cell infiltration (P < 0.0001), and effector cytokine levels compared to WT recipients. Batf3-deficiency greatly reduced DNGR-1⁺ DC-infiltration, CAR (P < 0.0001), and fibrosis (P = 0.0382). CD8 cells infiltrating allografts of cytochrome C treated recipients, showed reduced production of CD8 effector cytokines (P < 0.05). Further, alloreactive CD8⁺ T cell response in indirect pathway IFN-γ ELISPOT was reduced in Clec9a^-/- recipient mice (P = 0.0283). Blockade of DNGR-1 by antibody, similar to genetic elimination of the receptor, reduced CAR (P = 0.0003), fibrosis (P = 0.0273), infiltration of CD8⁺ cells (p = 0.0006), and effector cytokine levels. DNGR-1-dependent alloantigen cross-presentation by DNGR-1⁺ DCs induces alloreactive CD8⁺ cells that induce CAR and fibrosis. Antibody against DNGR-1 can block this process and prevent CAR and fibrosis.

CCR4 expression on host T cells is a driver for alloreactive responses and lung rejection

Despite current immunosuppressive strategies, long-term lung transplant outcomes remain poor due to rapid allogenic responses. Using a stringent mouse model of allo-airway transplantation, we identify the CCR4-ligand axis as a central node driving secondary lymphoid tissue homing and activation of the allogeneic T cells that prevent long-term allograft survival. CCR4 deficiency on transplant recipient T cells diminishes allograft injury and when combined with CTLA4-Ig leads to an unprecedented long-term lung allograft accommodation. Thus, we identify CCR4-ligand interactions as a central mechanism driving allogeneic transplant rejection and suggest it as a potential target to enhance long-term lung transplant survival.

Immunological Alterations due to Hemodialysis Might Interfere with Early Complications in Renal Transplantation

BACKGROUND

Chronic or intercurrent alterations of the immune system in patients with end-stage renal disease (CKD) and intermittent hemodialysis (CKD5D, HD) have been attributed to an acute rejection of renal allograft.

METHODS

Leukocyte subsets in flow cytometry, complement activation, and concentrations of TGFβ, sCD30 (ELISA), and interleukins (CBA) of fifteen patients eligible for renal transplantation were analyzed before, during, and after a regular HD.

RESULTS

Before HD, the median proportion of CD8+ effector cells, CD8+ CCR5+ effector cells, and HLA-DR+ regulatory T cells as well as the median concentration of soluble CD30 increased and naive CD8+ T cells decreased. During HD, there was a significant decrease in CD4- CD8- T cells (p < 0.001) and an increase in CD25+ T cells (p = 0.026), sCD30 (p < 0.001), HLA-DR+ regulatory T cells (p = 0.005), and regulatory T cells (p = 0.003). TGFβ and sCD30 increased significantly over time. The activity of the classical complement pathway started to slightly increase after the first hour of HD and lasted until fifteen minutes after finishing dialysis. The decrease in the functional activity of the alternative pathway was only transient and was followed by a significant increase within 15 minutes after finishing the treatment.

CONCLUSION

HD might interact with the allograft outcome by influencing T cell subsets and activation of the complement system in a biphasic course.

Immunomodulatory activity of glycodelin: implications in allograft rejection

Glycodelin is an immunomodulator, indispensable for the maintenance of pregnancy in humans. The glycoprotein induces apoptosis in activated CD4⁺ T cells, monocytes and natural killer (NK) cells, and suppresses the activity of cytotoxic T cells, macrophages and dendritic cells. This study explores the immunosuppressive property of glycodelin for its possible use in preventing graft rejection. Because glycodelin is found only in certain primates, the hypothesis was investigated in an allograft nude mouse model. It is demonstrated that treatment of alloactivated mononuclear cells with glycodelin thwarts graft rejection. Glycodelin decreases the number of activated CD4⁺ and CD8⁺ cells and down-regulates the expression of key proteins known to be involved in graft demise such as granzyme-B, eomesodermin (EOMES), interleukin (IL)-2 and proinflammatory cytokines [tumour necrosis factor (TNF)-α and IL-6], resulting in a weakened cell-mediated immune response. Immunosuppressive drugs for treating allograft rejection are associated with severe side effects. Glycodelin, a natural immunomodulator in humans, would be an ideal alternative candidate.

Targeting CD8 T-Cell Metabolism in Transplantation

Infiltration of effector CD8 T cells plays a major role in allograft rejection, and increases in memory and terminally differentiated effector memory CD8 T cells are associated with long-term allograft dysfunction. Alternatively, CD8 regulatory T cells suppress the inflammatory responses of effector lymphocytes and induce allograft tolerance in animal models. Recently, there has been a renewed interest in the field of immunometabolics and its important role in CD8 function and differentiation. The purpose of this review is to highlight the key metabolic pathways involved in CD8 T cells and to discuss how manipulating these metabolic pathways could lead to new immunosuppressive strategies for the transplantation field.

Peripheral blood biomarkers for the characterization of alloimmune reactivity after pediatric liver transplantation

Individualization of immunosuppressive medications is an important objective in transplantation medicine. Reliable biomarkers to distinguish between patients dependent from intensive immunosuppressive therapy and those where therapy can be minimized among pediatric transplant recipients receiving immunosuppressive medications are still not established. We evaluated the potential of cross-sectional quantification of regulatory T cells, lymphocyte subsets, and cytokine concentrations as biomarkers in 60 pediatric liver transplant recipients with AR, CR, or normal graft function and in 11 non-transplanted patients. Transplant recipients presenting with AR had significantly higher CD8+ T-cell counts, significantly higher concentrations of IL-2, and increased levels of IFN-γ compared with asymptomatic patients or controls. Regulatory T-cell numbers did not differ between children with rejection and children with good graft function. A tendency toward increased concentrations of IL-4 and TGF-β was detected in transplant recipients with good graft function. Cross-sectional parameters of peripheral regulatory T cells in pediatric liver transplant recipients do not seem to be valuable biomarkers for individualizing immunosuppressive therapy prior to the weaning process. Lymphocyte subsets, IL-2, IFN-γ, IL-4, and TGF-β serum concentrations may be helpful to identify children in whom immunosuppression can be reduced or discontinued.

Cytokine concentrations and regulatory T cells in living donor and deceased donor liver transplant recipients

Outcomes of pediatric liver transplantation have constantly improved in the last decade. Living-related liver transplantation does not seem to improve long-term outcomes following liver transplantation, but few studies have evaluated immunological parameters of the alloimmune response after living vs. deceased donor organ transplantation. We analyzed numbers of regulatory T cells, lymphocyte subsets, and serum cytokine concentrations in 12 pediatric recipients of living-related liver transplants and in 28 pediatric recipients of deceased donor organs during their annual follow-ups. Transplant recipients who underwent living donor organ transplantation had significantly higher numbers of regulatory T cells and IL-4 serum concentrations than recipients of deceased donor organs; both of these factors are associated with beneficial outcomes and transplantation tolerance. Living-related liver transplantation may have potentially beneficial immunological aspects, although long-term outcomes do not seem to be better in recipients of living donor organs than in recipients of deceased donor organs. Further studies are needed to compare immunological aspects of the two transplant procedures.

A direct comparison of rejection by CD8 and CD4 T cells in a transgenic model of allotransplantation

INTRODUCTION

The relative contributions of CD4+ and CD8+ T cells to transplant rejection remain unknown. The authors integrated a previous model of CD4-mediated graft rejection with a complementary model of CD8-mediated rejection to directly compare the function of graft-reactive CD4+ and CD8+ lymphocytes in vivo in a model where rejection requires transgenic T cells. These studies allow direct comparison of CD4 and CD8 T cell responses to the same antigen without the confounding effects of T cell depletion or homeostatic proliferation.

MATERIALS AND METHODS

Clone 4 and TS1 mice possess MHC class I- and II-restricted CD8+ and CD4+ T cells, respectively, which express transgenic T cell receptors that recognize the influenza hemagglutinin antigen (HA). We compared the in vivo response of CFSE-labeled, HA-specific transgenic CD8+ and CD4+ T cells after adoptive transfer into syngeneic BALB/c mice grafted with HA-expressing skin.

RESULTS

As in the authors' CD4+ model, HA104 skin was consistently rejected by both Clone 4 mice (n=9, MST: 14.2) and by 5 x 10(5) Clone 4 lymphocytes transferred to naive BALB/c hosts that do not otherwise reject HA+ grafts. Rejection correlated with extensive proliferation of either graft-reactive T cell subset in the draining lymph nodes, and antigen-specific CD4+ and CD8+ cells acquired effector function and proliferated with similar kinetics.

CONCLUSIONS

These data extend the authors' unique transgenic transplantation model to the investigation of CD8 T cell function. The initial results confirm fundamental functional similarity between the CD4 and CD8 T cell subsets and provide insight into the considerable redundancy underlying T cell mechanisms mediating allograft rejection.

Interleukin-17 and airway inflammation: a longitudinal airway biopsy study after lung transplantation

BACKGROUND

Interleukin-17 (IL-17) is a pro-inflammatory cytokine produced from CD4+ T cells and is associated with neutrophilia in infection, ischemia-reperfusion injury, and possibly acute and chronic rejection (bronchiolitis obliterans syndrome, or BOS) after lung transplantation (LTx). Everolimus (ERL) decreases acute rejection, possibly via decreasing airway CD4+ cells and neutrophils. This prospective study aims to assess: (1) the possible role of IL-17 as a link between LTx clinical outcomes (such as infection, acute rejection and BOS) and airway immunopathologic measures from endobronchial biopsy (EBB) and bronchoalveolar lavage (BAL); and (2) any differences in IL-17 production between ERL and azathioprine (AZA)-based immunosuppression.

METHODS

This sub-study, from a larger, prospective clinical ERL vs AZA randomized, controlled trial, examines EBB IL-17 expression, relating this to clinical outcomes, BAL and EBB cell counts. EBB IL-17 staining was measured by immunohistologic techniques and expressed as cells per square millimeter of lamina propria.

RESULTS

Thirty-four LTx patients were randomized in a double-blind study (ERL = 19, AZA = 15) and underwent a total of 113 bronchoscopies over a 3-year follow-up period. Twenty-six EBBs were taken from LTx recipients with BOS of at least Grade 0p (10 patients). Univariate associations correlated IL-17 positively with EBB CD8+ cells (R2 = 0.010, p = 0.001) and negatively with days post-LTx (R2 = 0.07, p = 0.002). In a multivariate model, IL-17 variability was explained by: days post-LTx (6.2%, p = 0.02); EBB CD8+ (5.9%, p = 0.02); cytomegalovirus mismatch (6.1%, p = 0.02); BAL lymphocyte percentage (4.2%, p = 0.05); and clinical infection (3.7%, p = 0.06).

CONCLUSIONS

IL-17 is associated with the early post-LTx time period and airway CD8+ cells. Unexpectedly, rejection grade, BOS, BAL IL-8 and neutrophil counts are not associated. ERL appears not to directly affect IL-17, despite its effects on CD4 cells.

Lymphoid cell proliferation in renal transplants: biologic and diagnostic implications

It is unclear whether alloreaction develops in peripheral lymphoid organs and effector cells being recruited to the target organs, or the entire process of alloreaction can happen within the transplanted kidneys. Interstitial inflammatory cell (IIC) proliferation was evaluated by MIB-1 antigen immunostain and the rate expressed as positive cells/1000 cells. This rate was higher in acute cell-mediated rejection (ACR) (25.7, n = 14) compared with normal kidney (0.4, n = 8), acute tubular necrosis (1.2, n = 8), chronic allograft nephropathy (CAN, 2.4, n = 20), and native kidneys with diverse diseases (9.2, n = 63); but was comparable to that in CAN with significant IIC (20.6, n = 16). 10.1% and 8.3% of T lymphocytes underwent proliferation in ACR with or without CAN, whereas only rare B lymphocytes or macrophages showed this change (<1.2%), regardless of diagnostic categories. All biopsies diagnosed as ACR in conjunction with a high rate of MIB-1 + IIC and 9/12 biopsies with CAN and significant IIC in which ACR was diagnosed due to a high rate of MIB-1 + IIC, responded to anti-rejection therapy. Proliferation of IIC involves predominantly T lymphocytes. These observations provide support for the concept of in situ alloimmunization, and facilitate the diagnosis of ACR.

Link between immune cell infiltration and mitochondria-induced cardiomyocyte death during acute cardiac graft rejection

Acute cardiac graft rejection (ACGR) is associated with cardiomyocyte apoptosis. We investigated the respective role of the Fas/FasL and mitochondrial permeability transition pore (mPTP) pathways in cardiomyocyte apoptosis accompanying ACGR. Heterotopic cardiac transplantations were performed in 7-9-week old C57BL6 or C3H mice. Wild type or Fas-deficient (lpr) mice underwent syngeneic (GS) or allogeneic (GA) transplantation, and received either saline or NIM811, a specific inhibitor of the mPTP. At day 5, we assessed ACGR by histology, cardiomyocyte apoptosis by caspase-3 activity and cytochrome c release, Ca(2+)-induced mPTP opening by a potentiometric approach, and expression of Fas, FasL, TNFalpha, perforin, granzyme using RT-PCR. Myocardial infiltration of CD8(+) T lymphocytes was performed by immunohistochemistry. Allogenic transplantation increased infiltration of inflammatory cells, upregulated FasL, perforin, granzyme, and TNFalpha, favored Ca(2+)-induced mPTP opening and increased caspase-3 activity and cytochrome c release in WT grafts. NIM811, but not Fas-deficiency, significantly reduced all these effects. NIM811 also limited infiltration of CD8(+) into WT and lpr transplants. These data suggest that the mPTP pathway plays a major role in cardiomyocyte apoptosis associated with ACGR. Inhibition of mPTP opening may attenuate cardiomyocyte apoptosis either directly or indirectly via a limitation of CD8(+) T-cell activation.

Fas/FasL and perforin/granzyme pathway in acute rejection and diffuse alveolar damage after allogeneic lung transplantation?a human biopsy study

Acute rejection and diffuse alveolar damage are major problems during the early time after transplantation. Against this background, lung biopsies after allogeneic lung transplantation were studied using immunohistochemistry. Biopsies with acute rejection, diffuse alveolar damage and morphological inconspicuous biopsies were chosen. The objectives of this study were to ascertain: (a) if and how CD4 and CD8 T cells contribute to allograft rejection and diffuse alveolar damage, (b) whether there is a correlation of the chemoattractant regulated on activation normal T cells (RANTES) with the mononuclear infiltrate and (c) whether perforin/granzyme and Fas/FasL pathways contribute to lung injury after lung transplantation. Our results show that CD4(+) and CD8(+) T cells were increased in biopsies with acute rejection and, to a minor extent, also in biopsies with diffuse alveolar damage due to reperfusion injury. RANTES expression of T cells was increased in biopsies with acute rejection. Perforin seemed to have a dual role in the alloimmune response. In one regard, it had a cytolytic function in the acute rejection process, and, in contrast, it may be responsible for downregulating both CD4- and CD8-mediated alloimmune responses. The FasL/Fas pathway is not only important for induction of apoptosis during rejection but is also a mechanism of lung injury in the development of diffuse alveolar damage.