CD4+25+ regulatory T cells limit Th1-autoimmunity by inducing IL-10 producing T cells following human lung transplantation

An instructive role of donor macrophages in mixed chimeras in the induction of recipient CD4(+)Foxp3(+) Treg cells

The immune regulatory function of macrophages (Møs) in mixed chimeras has not been determined. In the present study, with a multi-lineage B6-to-BALB/c mixed chimeric model, we examined the ability of donor-derived splenic Møs in the induction of regulatory T cells (Treg). B6 splenic Møs from mixed chimeras induced significantly less cell proliferation, more IL-10 and TGF-β, and less IL-2 and IFN-γ productions of CD4(+) T cells from BALB/c mice than naive B6 Møs did, whereas they showed similar stimulatory activity to the third part C3H CD4(+) T cells. Importantly, highly purified donor F4/80(+)CD11c(-) Møs efficiently induced recipient CD4(+)Foxp3(+) Treg cells from CD4(+)CD25(-)Foxp3(-) T cells. Furthermore, donor Møs of mixed chimeras produced more IL-10 and less IFN-γ than those of naive mice when cultured with BALB/c but not the third party C3H CD4(+) T cells. Induction of recipient CD4(+) Treg cells by donor Møs was significantly blocked by anti-IL-10, but not by anti-TGF-β mAb. Therefore, donor Møs have the ability to induce recipient CD4(+)Foxp3(+) Treg cells in a donor antigen-specific manner, at least partially, via an IL-10-dependent pathway. This study for the first time showed that, in mixed allogeneic chimeras, donor Møs could be specifically tolerant to recipients and gained the ability to induce recipient but not the third party Foxp3(+) Treg cells. Whether this approach is involved in transplant immune tolerance needs to be determined.

Efficient peripheral construction of functional human regulatory CD4(+)CD25(high)Foxp3(+) T cells in NOD/SCID mice grafted with fetal human thymus/liver tissues and CD34(+) cells

Regulatory T cells, especially CD4(+)CD25(+) regulatory T cells are critical regulators of immune tolerance in humans and mice. Mice with humanized immunity have been developed by various transplantation strategies of human tissues or cells related to immunity, which are being extensively applied in biomedical research. However, it is unclear whether human CD4(+)CD25(+) regulatory T cells can normally develop in human thymic grafts and efficiently populate in the periphery in NOD/SCID mouse recipients. In human thymic grafts, high percentage of mature human CD4(+)CD25(high) regulatory T cells was detected. Human CD4(+)CD25(+) regulatory T cells maturing in fetal human thymus grafts could subsequently output to the periphery of NOD/SCID mouse recipients. Importantly, these cells exhibited Foxp3(+)CD45RO(+)CTLA4(+)CD127(-) phenotype, similarly to those in healthy individuals. In addition, human CD4(+)CD25(+) regulatory T cells maturing in human thymic grafts suppressed proliferative response of CD4(+)CD25(-) T cells to allogeneic antigens, though the peripheral CD4(+)CD25(+) regulatory T cells in fetal human thymus-grafted NOD/SCID mice showed somewhat decreased immunosuppressive ability compared with normal CD4(+)CD25(+) regulatory T cells. Thus, this humanized animal model is suitable for examining development and function of human CD4(+)CD25(+) regulatory T cells in vivo.

A role for antibodies to human leukocyte antigens, collagen-V, and K-α1-Tubulin in antibody-mediated rejection and cardiac allograft vasculopathy

BACKGROUND

We determined the role of donor-specific antibodies (DSA) and antibodies (Abs) to self-antigens, collagen-V (Col-V), and K-α1-Tubulin (KAT) in pathogenesis of acute antibody-mediated rejection (AMR) and cardiac allograft vasculopathy (CAV) after human heart transplantation (HTx).

METHODS

One hundred thirty-seven HTx recipients, with 60 early period (≤ 12 months) and 77 late period (>12 months), were enrolled in this study. Circulating DSA was determined using LUMINEX. Abs against Col-I, II, IV, V, and KAT were measured using ELISA. Frequency of CD4+T helper cells (CD4+Th) secreting interferon (IFN)-γ, interleukin (IL)-5, -10, or -17 specific to self-antigens were determined using Enzyme Linked Immunosorbent Spot assay.

RESULTS

A significant association between AMR and DSA was demonstrated. Development of DSA in AMR patients correlated well with the development of auto-Abs to Col-V (AMR[+]: 383 ± 72 μg/mL, AMR[-]: 172 ± 49 μg/mL, P=0.033) and KAT (AMR[+]: 252 ± 49 μg/mL, AMR[-]: 61 ± 21 μg/mL, P=0.014). Patients who developed AMR demonstrated increased frequencies of CD4+Th secreting IFN-γ and IL-5 with reduction in IL-10 specific for Col-V/KAT. Patients diagnosed with CAV also developed DSA and auto-Abs to Col-V (CAV[+]: 835 ± 142 μg/mL, CAV[-]: 242 ± 68 μg/mL, P=0.025) and KAT (CAV[+]: 768 ± 206 μg/mL, CAV[-]: 196 ± 72 μg/mL, P=0.001) with increased frequencies of CD4+Th secreting IL-17 with reduction in IL-10 specific for Col-V/KAT. CONCLUSIONS.: Development of Abs to human leukocyte antigens and self-antigens are associated with increases in CD4+Th secreting IFN-γ and IL-5 in AMR and IL-17 in CAV, with reduction in CD4+Th secreting IL-10 in both AMR and CAV.

Alloimmunity-induced autoimmunity as a potential mechanism in the pathogenesis of chronic rejection of human lung allografts

BACKGROUND

Bronchiolitis obliterans syndrome (BOS) is a major cause of morbidity and mortality after lung transplantation (LTx). We sought to better understand the relationship between alloimmune responses and autoimmunity and, subsequently, how autoimmunity leads to chronic rejection.

METHODS

We analyzed the development of donor-specific antibodies (Abs) in LTx by flow PRA and the development of Abs to K-α1 tubulin (K-α1T) and collagen V (ColV) by ELISA. The frequency of K-α1T- and ColV-specific T cells that secrete IFN-γ, IL-17 and IL-10 in LTx recipients was measured by ELISPOT.

RESULTS

In a retrospective analysis of 42 LTx recipients, we demonstrated a strong correlation between development of donor-specific anti-HLA Abs, Abs to self-antigens and BOS (p < 0.05). To test the hypothesis that alloimmunity is related to an immune response to self-antigens, we analyzed 103 LTx patients prospectively for the development of donor-specific Abs (DSA) and Abs to self-antigens. A total of 42.7% of recipients developed DSA and 30.1% developed Abs to K-α1T and ColV. Development of DSA preceded development of Abs to self-antigens. BOS(+) patients had higher frequency of T cells secreting IL-17 (p < 0.01) and IFN-γ (p < 0.05) with decreased IL-10 (p < 0.05) when compared with BOS(-) patients.

CONCLUSIONS

Based on these results we propose that alloimmune responses to donor HLA can induce autoimmune responses to airway epithelial self-antigens, characterized by activation of the IL-17 pathway. These immune responses to self-antigens along with alloimmunity contribute to the pathogenesis of BOS. Strategies to prevent development of autoimmunity may be play a key role in preventing the development of chronic rejection.

Regulatory T cells in lung transplantation--an emerging concept

Lung transplantation represents an option for patients with a variety of end-stage lung diseases. While surgical advances have led to improvements in short-term survival, long-term survival is limited by chronic rejection termed bronchiolitis obliterans syndrome (BOS). A growing body of work is devoted to determining why some patients develop BOS. One avenue of interest that has emerged recently is the role that regulatory T cells (Tregs) may have in protection from BOS. In this review, we will discuss the evidence that Tregs are relevant to outcomes following transplant. We will discuss the relevant animal models, in vitro assays, and human observational studies that support a role for Tregs. We will also explore the interplay between injurious T cells such as Th17 cells and Tregs as well as the effect that additional cell types and chemokines have on the balance between inflammation and regulation. Finally, we will review emerging therapies which may harness the ability of Tregs to lessen the effects of BOS.

Respiratory virus-induced dysregulation of T-regulatory cells leads to chronic rejection

BACKGROUND

Lower respiratory viral infections predispose to bronchiolitis obliterans syndrome (BOS). In addition, there is emerging evidence to support the role of autoimmunity in the pathogenesis of BOS. Because CD4(+)CD25(+)Foxp3(+) regulatory T-cells (Treg) control autoimmunity, we tested the hypothesis that respiratory virus-induced Treg dysfunction leads to BOS.

METHODS

Treg frequency was monitored using flow cytometry. Apoptosis, cytokines, and antibodies were analyzed using annexin V assay, LUMINEX, and enzyme-linked immunosorbent assay, respectively. Murine studies were performed using the orthotopic tracheal transplant model.

RESULTS

(A) Human studies: Treg troughs (decrease >50% of baseline) were found in 13 (43.3%) of 30 lung transplant recipients. Treg isolated during troughs revealed increased apoptosis (37.8%). Patients with Treg troughs had increased prevalence of antibodies to self-antigens collagen type I (23.1% vs 5.8% pretrough), collagen V (7.7% vs 0%), and k-alpha tubulin (30.7% vs 11.7%, p < 0.01) at 6 months post-trough. Increased number of Treg troughs correlated with more rapid onset of BOS. (B) Murine studies: Infection of tracheal transplant recipients with murine parainfleunza sendai virus led to increased Treg apoptosis (50.5%) in the draining lymph nodes. Vaccination against sendai virus prior to transplant abrogated apoptosis of Treg. In vitro, sendai virus-infected, but not naive, tracheal epithelial cells demonstrated upregulation of FasL (>3.5-fold) and induction of co-cultured Treg apoptosis (5.6-fold increase).

CONCLUSIONS

Respiratory viral infections cause Treg apoptosis which leads to the development of de novo autoimmunity that may play a role in the pathogenesis of BOS.

Decreased percentage of CD4+FoxP3+ cells in bronchoalveolar lavage from lung transplant recipients correlates with development of bronchiolitis obliterans syndrome

BACKGROUND

Lung transplantation, in patients with end-stage lung disease, is limited by chronic rejection, which occurs with an incidence and severity exceeding most other transplanted organs. Alloimmune responses play an important role in progression to chronic rejection that manifests as bronchiolitis obliterans syndrome (BOS), but no biomarker can currently predict the progression to BOS. Studies in animal models suggest that intragraft T regulatory cells (Tregs) are important in maintaining transplantation tolerance, and FoxP3 is the protoypic Treg marker.

METHODS

Leukocytes in blood and bronchoalveolar lavage (BAL) fluid were compared for expression of FoxP3 by flow cytometry in 14 stable lung transplant recipients and 6 lung transplant recipients who eventually developed BOS.

RESULTS

Stable patients, compared with patients who subsequently developed BOS, consistently had a significantly increased percentage of FoxP3 cells among CD4 cells in BAL and greater levels of the Treg-attracting chemokine CCL22. These differences were observed in limited sequential analyses, before, at the time of acute rejection, and postacute rejection. In this pilot study, a threshold of 3.2% CD4/FoxP3 cells in the BAL distinguished stable recipients from those subsequently developing BOS within the first 2 years posttransplantation.

CONCLUSION

The proportion of FoxP3 cells among CD4 cells in BAL may help to predict lung allograft outcome and guide therapeutic immunosuppression in lung transplant recipients.

Alloimmunity and autoimmunity in chronic rejection

PURPOSE OF REVIEW

Recent studies demonstrate an increasing role for alloimmune responses in the disruption of self-tolerance leading to immune responses to self-antigens that play a role in the immunopathogenesis of chronic rejection following solid organ transplantation. This review summarizes recent studies and implications for the alloimmune-response-induced de-novo development of autoimmune responses following solid organ transplantations.

RECENT FINDINGS

Immediately following organ transplantation, several factors lead to enduring an inflammatory milieu. Studies from our laboratory and others have demonstrated that development of antihuman leukocyte antigen antibodies precedes the development of chronic rejection. Using an in-vivo murine model, we have demonstrated that administration of anti-major histocompatibility complex (MHC) class I directly into the native lungs leads to chronic rejection pathology. Further, the in-vitro ligation of epithelial cell surface MHC class I molecules by specific anti-MHC can lead to cell activation and production of fibrinogenic growth factors.

SUMMARY

On the basis of these findings, we hypothesized that alloimmune responses can lead to autoimmunity, thus playing an important role in chronic rejection. Characterization of both the temporal occurrence and functional significance of antibodies to self-antigens may provide insight into the pathogenesis of chronic rejection and these antibodies can serve as clinically useful biomarkers.

Antibodies to self-antigens predispose to primary lung allograft dysfunction and chronic rejection

BACKGROUND

Primary graft dysfunction (PGD) is a known risk factor for bronchiolitis obliterans syndrome (BOS) after lung transplantation. Here, we report that preformed antibodies to self-antigens increase PGD risk and promote BOS.

METHODS

Adult lung transplant recipients (n = 142) were included in the study. Primary graft dysfunction and BOS were diagnosed based on International Society for Heart and Lung Transplantation guidelines. Antibodies to self-antigens k-alpha-1 tubulin, collagen type V, and collagen I were quantitated using standardized enzyme-linked immunosorbent assays, and cytokines were analyzed using Luminex immunoassays (Biosource International, Camirillo, CA). Human leukocyte antigen (HLA) antibodies were measured using Flow-PRA (One Lambda, Canoga Park, CA).

RESULTS

Lung transplant recipients with pretransplant antibodies to self-antigens had increased risk of PGD (odds ratio 3.09, 95% confidence interval: 1.2 to 8.1, p = 0.02) compared with recipients without. Conversely, in patients with PGD, 34.7% were positive for pretransplant antibodies whereas in the PGD negative group, only 14.6% had antibodies (p = 0.03). Antibody positive patients demonstrated high levels of proinflammatory cytokines interleukin (IL)-1β (2.1-fold increase), IL-2 (3.0), IL-12 (2.5), IL-15 (3.0), and chemokines interferon-inducible protein-10 (3.9) and monocyte chemotactic protein-1 (3.1; p < 0.01 for all). On 5-year follow-up, patients without antibodies showed greater freedom from development of HLA antibodies compared with patients who had antibodies (class I: 67% versus 38%, p = 0.001; class II: 71% versus 41%, p < 0.001). Patients with pretransplant antibodies were found to have an independent relative risk of 2.3 (95% confidence interval: 1.7 to 4.5, p = 0.009) for developing BOS.

CONCLUSIONS

Presence of antibodies to self-antigens pretransplant increases the risk of PGD immediately after transplant period and BOS on long-term follow-up. Primary graft dysfunction is associated with an inflammatory cascade that augments the alloimmune (anti-HLA) response that predisposes to BOS.

Collagen V and vascular injury promote lung architectural changes in systemic sclerosis

BACKGROUND

Systemic sclerosis (SSc) is a multisystem disorder characterized by inflammation, fibrosis and vascular damage. The aim of this study was to evaluate the interactions between basement membrane disruption, endothelial injury and collagen V deposition on the vascular wall, as well as their association with pulmonary function tests in patients with SSc.

METHOD

The endothelial apoptosis was assessed by TUNEL and electron microscopy, and quantified through the point-counting technique. To evaluate basement membrane integrity, laminin immunostaining and electron microscopy were used. Immunofluorescence and morphometric analysis were used to determine the amount of collagen V in the vascular walls in 23 open lung biopsies of patients with SSc without pulmonary hypertension. Normal lung tissue was obtained from five individuals who had died of traumatic injuries.

RESULTS

The apoptosis index in SSc was higher in the endothelial cells (13.83 +/- 6.83) when compared with the control (2.51 +/- 2.06) group (P < 0.001) and confirmed by electron microscopy. We observed an important disruption of the basement membrane on the vascular wall shown by discontinuous laminin immunostaining and electron microscopy. An increase in collagen V on the vascular wall of the SSc group was observed (45.28 +/- 13.21), when compared with control group (22.90 +/- 4.13, P < 0.001), and this difference was statistically significant. An inverse correlation was found between vital capacity, forced vital capacity, forced expiratory volume in 1 s, vascular collagen V and endothelial apoptosis (P < 0.05).

CONCLUSIONS

We conclude that the endothelial apoptosis and vascular collagen V interaction reinforce the vascular pathway in the SSc pathogenesis. Further studies are needed to determine whether this relationship is causal or consequential.

Protection against bronchiolitis obliterans syndrome is associated with allograft CCR7+ CD45RA- T regulatory cells

Bronchiolitis obliterans syndrome (BOS) is the major obstacle to long-term survival after lung transplantation, yet markers for early detection and intervention are currently lacking. Given the role of regulatory T cells (Treg) in modulation of immunity, we hypothesized that frequencies of Treg in bronchoalveolar lavage fluid (BALF) after lung transplantation would predict subsequent development of BOS. Seventy BALF specimens obtained from 47 lung transplant recipients were analyzed for Treg lymphocyte subsets by flow cytometry, in parallel with ELISA measurements of chemokines. Allograft biopsy tissue was stained for chemokines of interest. Treg were essentially all CD45RA(-), and total Treg frequency did not correlate to BOS outcome. The majority of Treg were CCR4(+) and CD103(-) and neither of these subsets correlated to risk for BOS. In contrast, higher percentages of CCR7(+) Treg correlated to reduced risk of BOS. Additionally, the CCR7 ligand CCL21 correlated with CCR7(+) Treg frequency and inversely with BOS. Higher frequencies of CCR7(+) CD3(+)CD4(+)CD25(hi)Foxp3(+)CD45RA(-) lymphocytes in lung allografts is associated with protection against subsequent development of BOS, suggesting that this subset of putative Treg may down-modulate alloimmunity. CCL21 may be pivotal for the recruitment of this distinct subset to the lung allograft and thereby decrease the risk for chronic rejection.

Ecto-5'-nucleotidase (CD73) attenuates allograft airway rejection through adenosine 2A receptor stimulation

There are multiple drivers of leukocyte recruitment in lung allografts that contribute to lymphocytic bronchitis (LB) and bronchiolitis obliterans (BO). The innate mechanisms driving (or inhibiting) leukocyte trafficking to allografts remain incompletely understood. This study tested the hypothesis that CD73 (ecto-5'nucleotidase), an enzyme that catalyzes the conversion of AMP to adenosine, is a critical negative regulator of LB and BO. Implantation of tracheal allografts from wild type (WT) mice into CD73(-/-) recipients revealed a striking increase in airway luminal obliteration at 7 d (62 +/- 4% and 47 +/- 5% for CD73(-/-) and WT allograft recipients, respectively; p = 0.046). There was also a concordant increase in CD3(+) lymphocytic infiltration (523 +/- 41 cells and 313 +/- 43 cells for CD73(-/-) and WT allograft recipients, respectively; p = 0.013). Because real-time PCR revealed a 43-fold upregulation of mRNA for the adenosine A2A receptor (A2AR) in WT allografts compared with WT isografts (p = 0.032), additional experiments were performed to determine whether the protective effect of CD73 was due to generation of adenosine and its stimulation of the A2AR. Treatment of WT recipients with an A2AR agonist significantly reduced CD3(+) lymphocyte infiltration and airway luminal obliteration; similar treatment of CD73(-/-) recipients rescued them from LB and airway obliteration. These data implicate CD73 acting through adenosine generation and its stimulation of the A2AR as a critical negative modulator of lymphocyte recruitment into airway allografts. The CD73/adenosine axis might be a new therapeutic target to prevent BO.

Association between decreases in type V collagen and apoptosis in mouse lung chemical carcinogenesis: a preliminary model to study cancer cell behavior

OBJECTIVE

The importance of type V collagen and its relationships with other types of collagen and with vascular and epithelial apoptosis were studied in a model of chemical carcinogenesis in the mouse lung.

METHODS

TWO GROUPS OF MALE BALB/C MICE WERE STUDIED: a) animals that received two intraperitoneal doses of 3 g/kg urethane carcinogen (urethane group = 24); and b) animals submitted to a sham procedure, comparable to the test group (control group = 7). Both groups were sacrificed after 120 days. In situ detection of apoptosis, immunohistochemistry, immunofluorescence and histomorphometry were used to evaluate the fraction occupied by the tumor, vascular and epithelial apoptosis, and type V, III and I collagen fibers in the lung parenchyma from both groups.

RESULTS

The lung parenchyma from the urethane group showed low fractions of vascular and epithelial apoptosis as well as reduced type V collagen fibers when compared to the control group. A significant direct association was found between type V and III collagen fibers and epithelial apoptosis, type V collagen fibers and vascular apoptosis, and type V and type I collagen fibers.

CONCLUSION

The results show that a direct link between low amounts of type V collagen and decreased cell apoptosis may favor cancer cell growth in the mouse lung after chemical carcinogenesis, suggesting that strategies aimed at preventing decreased type V collagen synthesis or local responses to reduced apoptosis may have a greater impact in lung cancer control.

Genetic polymorphisms in MMP7 and reduced serum levels associate with the development of bronchiolitis obliterans syndrome after lung transplantation

BACKGROUND

Pulmonary epithelium is the primary target of injury in the development of bronchiolitis obliterans syndrome (BOS) after lung transplantation. Matrix metalloproteinases (MMP)-8 and -9 already have been implicated in the pathogenesis of BOS. MMP-7, which is involved in the repair of the lung epithelium, has not been studied in this respect. We hypothesized that genetic polymorphisms in MMP7 influence its expression and correlate with serum MMP-7 levels and the development of BOS.

METHODS

DNA was collected from 110 lung transplant recipients, including 21 patients with BOS. We genotyped 7 single nucleotide polymorphisms in MMP7 and measured serum MMP-7 levels. The control group comprised 422 healthy individuals.

RESULTS

BOS(pos) patients had lower levels of MMP-7 than BOS(neg) patients (7.87 vs 10.18 ng/ml). Significant differences in genotype and haplotype distribution between the BOS(pos) and BOS(neg) patients and controls were found. An increased risk for BOS development was found in patients homozygous for the major alleles of rs17098318, rs11568818, and rs12285347, and for the minor allele rs10502001 (odds ratio, 3.88-5.30). Haplotypes constructed with 3 or 4 risk alleles correlated with lower MMP-7 levels.

CONCLUSIONS

Genetic polymorphisms of MMP7 predispose to the development of BOS. Patients carrying these risk alleles express lower levels of MMP-7, which may contribute to aberrant tissue repair and culminate in the development of BOS.

Antihuman leukocyte antigen antibody-induced autoimmunity: role in chronic rejection

PURPOSE OF REVIEW

We provide evidence for the role of de-novo development of immune responses to self-antigens in the posttransplant period and its possible induction by alloimmunity in the pathogenesis of chronic rejection following lung, heart and kidney transplantation. The present review details recent findings for the two distinct yet interdependent immune processes in the immunopathogenesis of chronic rejection.

RECENT FINDINGS

The contribution of both humoral and cell-mediated alloimmune responses against mismatched donor histocompatibility antigens (HLA) in the pathogenesis of chronic rejection is well established. Recent studies have focused on development of immune responses to self-antigens during the posttransplant period and its correlation with chronic rejection. These self-antigens include myosin and vimentin in cardiac, K-alpha-1-tubulin and collagen-V in lung and angiotensin II type 1 receptor, collagen-IV and VI in kidney transplants. During the posttransplant period, the development of immune responses to self-antigens is facilitated by induction of a distinct subset of autoreactive T-helper cells referred to as Th17 cells.

SUMMARY

Following organ transplantation, tissue injury and remodeling inflicted by antibodies (Abs) to HLA antigens is conducive to develop autoimmunity. Abs to HLA and self-antigens are detectable in the serum of transplant recipients who develop chronic rejection. Anti-HLA Abs are often present transiently but precede the development of Abs to self-antigens.

Type V collagen-induced oral tolerance plus low-dose cyclosporine prevents rejection of MHC class I and II incompatible lung allografts

Autoimmunity to type V collagen (col(V)) is a major risk factor for lung allograft rejection. Although col(V)-induced oral tolerance abrogates rejection of minor histoincompatible lung transplants, its ability to prevent rejection of fully MHC incompatible lung allografts is unknown. Rat lung allografts fully incompatible at MHC class I and II loci (Brown Norway (RT1(n))) were transplanted into untreated Wistar Kyoto rat recipients (WKY, RT1(l)), or WKY rats were fed col(V) pretransplantation. To determine whether col(V) enhanced cyclosporine (CsA)-mediated immune suppression, WKY rats were treated with low-dose CsA (5 mg/kg), posttransplant, or oral col(V) plus CsA. The data showed that in contrast to col(V) or CsA, col(V) plus low-dose CsA significantly prevented rejection pathology, down-regulated alloantigen-induced production of IFN-gamma and IL-17A, and suppressed chemotaxis for lung macrophages in allograft bronchoalveolar lavage fluid that was associated with lower local levels of MCP-1 (CCL2). Col(V) plus CsA was associated with alloantigen-induced expression of IL-10 in mediastinal lymph node or splenic T cells, intragraft expression of IL-10 and Foxp3 in perivascular and peribronchiolar mononuclear cells, and constitutive production of IL-10 from allograft alveolar macrophages. These data demonstrate that col(V) enhances low-dose CsA-mediated immune suppression, and suggest a role for oral col(V) in immune modulation in lung transplantation.

Bronchiolitis obliterans after allogeneic hematopoietic stem cell transplantation

With improvements in supportive care, both long-term survival following allogeneic hematopoietic stem cell transplantations (HSCTs) and the indications for this procedure have increased. As a result, the number of patients living with long-term toxic effects due to HSCT has increased. A once rare condition of the donor immune cells attacking healthy host tissues, termed chronic graft-vs-host disease, has become a more common phenomenon. When chronic graft-vs-host disease affects the lung tissue, bronchiolitis obliterans syndrome ensues. Recent data suggest that bronchiolitis obliterans syndrome may affect up to 6% of HSCT recipients and dramatically alters survival, with overall survival of only 13% at 5 years. These statistics have not improved since the first presentation of this disease over 20 years ago. Challenges to the progress of medical management of bronchiolitis obliterans syndrome include difficulties and delays in diagnosis and a paucity of data on pathogenesis to direct new therapies. This article critically evaluates the current diagnostic criteria for bronchiolitis obliterans syndrome and reviews the epidemiology, pathogenesis, and available treatments. Improvements in survival will likely require early disease recognition, allowing for therapeutic modulation of disease prior to the development of irreversible airway obliteration.

Antibodies to MHC class I induce autoimmunity: role in the pathogenesis of chronic rejection

Alloimmunity to mismatched donor HLA-Ags and autoimmunity to self-Ags have been hypothesized to play an important role in immunopathogenesis of chronic rejection of transplanted organs. However, it is not known what role, if any, alloimmune response plays in inducing autoimmunity. To test whether Ab-developed posttransplantation to mismatched donor MHC induces autoimmunity and chronic rejection, we developed a murine model wherein anti-MHC class I Abs or control (C1.18.4/anti-keratin) were administered intrabronchially into native lungs. Animals receiving anti-MHC class I, but not control Abs, developed marked cellular infiltration around vessels and bronchiole of lung by day 15, followed by epithelial hyperplasia, fibrosis, and occlusion of the distal airways similar to chronic rejection following human lung transplantation. Lungs of mice receiving anti-MHC class I showed increased expression of chemokines, their receptors, and growth factors, and induced IL-17 as well as de novo Abs to self-Ags, K-alpha1 tubulin, and collagen V. IL-17 neutralization by anti-IL-17 resulted in reduction of autoantibody and lesions induced by anti-MHC class I Abs. Thus, our results indicate that Abs to donor MHC can induce autoimmunity, mediated by IL-17, which plays a pivotal role in chronic rejection postlung transplantation. Therefore, approaches to prevent autoimmunity should be considered for the treatment of chronic rejection postlung transplantation.

Bronchiolitis obliterans syndrome: alloimmune-dependent and -independent injury with aberrant tissue remodeling

Long-term success in lung transplantation continues to be challenged by chronic graft dysfunction, which is manifest as bronchiolitis obliterans syndrome (BOS). The mechanisms of BOS involve both immune-mediated pathways (rejection, autoimmune-like mechanisms), and alloimmune-independent pathways (infection, aspiration, ischemia, primary graft failure), which lead to a fibroproliferative responses. BOS correlates histologically with obliterative bronchiolitis in terminal bronchioles and evidence of aberrant remodeling in the airway epithelium, vasculature, stroma, and lymphoid system. A potentially important mechanism that supports the progressive and therapy-resistant nature of BOS is a continuous cycle of ongoing injury and aberrant remodeling. Namely, anatomical and functional abnormalities induce and exacerbate immune-mediated and alloimmune-independent pathways through various mechanisms (e.g., epithelial remodeling decreases mucociliary clearance that exacerbates aspiration-related injury). From this viewpoint, we review current therapeutic strategies and revisit the role of transplant surgeons in attenuating the initial transplant-related injuries to prevent the lung grafts from entering the remodeling-injury cycle.

Late primary graft dysfunction after lung transplantation and bronchiolitis obliterans syndrome

Primary graft dysfunction (PGD) is a common early complication after lung transplantation. We conducted a retrospective cohort study of 334 recipients to evaluate the impact of PGD graded at 24, 48 and 72 h on the risk of bronchiolitis obliterans syndrome (BOS) development (stage 1) and progression (stages 2 and 3). We constructed multivariable Cox proportional hazards models to determine the risk of BOS attributable to PGD in the context of other potential risk factors including acute rejection, lymphocytic bronchitis and respiratory viral infections. All grades of PGD at all time points were significant risk factors for BOS development and progression independent of acute rejection, lymphocytic bronchitis and respiratory viral infections. Specifically, PGD grade 1 at T24 was associated with a relative risk of BOS stage 1 of 1.93, grade 2 with a relative risk of 2.29 and grade 3 with a relative risk of 3.31. Furthermore, this direct relationship between the severity of PGD and the risk of BOS persisted at all time points. We conclude that all grades of PGD at all time points are independent risk factors for BOS development and progression. Future strategies that might attenuate the severity of PGD may mitigate the risk of BOS.

Activated effector and memory T cells contribute to circulating sCD30: potential marker for islet allograft rejection

T-cell activation up-regulates CD30 resulting in an increase in serum soluble CD30 (sCD30). CD4+ T cells, a major source for sCD30, play a significant role in the pathogenesis of rejection. In this study, sCD30 was measured pre- and posttransplant in mouse islet allograft models and human islet allograft recipients. sCD30 was measured by ELISA in diabetic C57BL/6, CD4Knockout (KO) and CD8KO islet allograft recipients. sCD30 increased significantly prior to rejection (1.8 +/- 1 days) in 80% of allograft recipients. Sensitization with donor splenocytes, or a second graft, further increased sCD30 (282.5 +/- 53.5 for the rejecting first graft vs. 374.6 +/- 129 for the rejecting second graft) prior to rejection suggesting memory CD4+ T cells contribute to sCD30. CD4KO failed to reject islet allograft and did not demonstrate sCD30 increase. CD8KO showed elevated (227 +/- 107) sCD30 (1 day) prior to rejection. High pretransplant sCD30 (>20 U/ml) correlated with poor outcome in human islet allograft recipients. Further, increase in sCD30 posttransplant preceded (3-4 months) loss of islet function. We conclude that sCD30 is released from activated CD4 T cells prior to islet allograft rejection and monitoring sCD30 can be a valuable adjunct in the follow-up of islet transplant recipients.

Chronic aspiration of gastric fluid induces the development of obliterative bronchiolitis in rat lung transplants

Long-term survival of a pulmonary allograft is currently hampered by obliterative bronchiolitis (OB), a form of chronic rejection that is unique to lung transplantation. While tracheobronchial aspiration from gastroesophageal reflux disease (GERD) has clinically been associated with OB, no experimental model exists to investigate this problem. Using a WKY-to-F344 rat orthotopic left lung transplant model, the effects of chronic aspiration on pulmonary allograft were evaluated. Recipients received cyclosporine with or without 8 weekly aspirations of gastric fluid into the allograft. Six (66.7%) of 9 allografts with aspiration demonstrated bronchioles with surrounding monocytic infiltrates, fibrosis and loss of normal lumen anatomy, consistent with the development of OB. In contrast, none of the allografts without aspiration (n = 10) demonstrated these findings (p = 0.002). Of the grafts examined grossly, 83% of the allografts with chronic aspiration but only 20% without aspiration appeared consolidated (p = 0.013). Aspiration was associated with increased levels of IL-1 alpha, IL-1 beta, IL-6, IL-10, TNF-alpha and TGF-beta in BAL and of IL-1 alpha, IL-4 and GM-CSF in serum. This study provides experimental evidence linking chronic aspiration to the development of OB and suggests that strategies aimed at preventing aspiration-related injuries might improve outcomes in clinical lung transplantation.

Immunological link between primary graft dysfunction and chronic lung allograft rejection

BACKGROUND

Primary graft dysfunction (PGD) in the immediate post-lung transplant period strongly increases the risk of chronic rejection (broncholitis obliterans syndrome). Here, we hypothesized that PGD-induced inflammation augments alloimmunity, thereby predisposing to broncholitis obliterans syndrome.

METHODS

Primary graft dysfunction and broncholitis obliterans syndrome were diagnosed according to the established International Society for Heart and Lung Transplantation criteria. Anti-human leukocyte antigen (HLA) alloantibodies were analyzed using Flow-PRA. Donor HLA class II-specific T cells were analyzed using interferon (IFN)-gamma ELISPOT. Serum levels of 25 cytokines and chemokines were measured using LUMINEX.

RESULTS

Of the 127 subjects, 29 (22.8%) had no PGD (grade 0), 42 (33.2%) had PGD-1, 36 (28.3%) had PGD-2, and 20 (15.7%) had PGD-3. Patients with PGD grades 1 to 3 (PGD(1-3)) had elevated proinflammatory mediators MCP-1, IP-10, interleukin (IL)-1 beta, IL-2, IFN-gamma, and IL-12 in the sera during the early posttransplant period compared with patients with PGD grade 0 (PGD(0)). On serial analysis, PGD(1-3) patients revealed increased development of de novo anti-HLA-II (5 years: 52.2% versus PGD(0) 13.5%, p = 0.008). However, no difference was found in anti-HLA-I alloantibody development (PGD(1-3) patients 48% versus PGD(0) 39.6%, p = 0.6). Furthermore, PGD(1-3) patients had increased frequency of donor HLA class II-specific CD4(+) T cells [(91.4 +/- 19.37) x 10(-6) versus (23.6 +/- 15.93) x 10(-6), p = 0.003].

CONCLUSIONS

Primary graft dysfunction induces proinflammatory cytokines that can upregulate donor HLA-II antigens on the allograft. Increased donor HLA-II expression along with PGD-induced allograft inflammation promotes the development of donor specific alloimmunity. This provides an important mechanistic link between early posttransplant lung allograft injury and reported association with broncholitis obliterans syndrome.

Chronic aspiration of gastric fluid induces the development of obliterative bronchiolitis in rat lung transplants

Long-term survival of a pulmonary allograft is currently hampered by obliterative bronchiolitis (OB), a form of chronic rejection that is unique to lung transplantation. While tracheobronchial aspiration from gastroesophageal reflux disease (GERD) has clinically been associated with OB, no experimental model exists to investigate this problem. Using a WKY-to-F344 rat orthotopic left lung transplant model, the effects of chronic aspiration on pulmonary allograft were evaluated. Recipients received cyclosporine with or without 8 weekly aspirations of gastric fluid into the allograft. Six (66.7%) of 9 allografts with aspiration demonstrated bronchioles with surrounding monocytic infiltrates, fibrosis and loss of normal lumen anatomy, consistent with the development of OB. In contrast, none of the allografts without aspiration (n = 10) demonstrated these findings (p = 0.002). Of the grafts examined grossly, 83% of the allografts with chronic aspiration but only 20% without aspiration appeared consolidated (p = 0.013). Aspiration was associated with increased levels of IL-1 alpha, IL-1 beta, IL-6, IL-10, TNF-alpha and TGF-beta in BAL and of IL-1 alpha, IL-4 and GM-CSF in serum. This study provides experimental evidence linking chronic aspiration to the development of OB and suggests that strategies aimed at preventing aspiration-related injuries might improve outcomes in clinical lung transplantation.

T regulatory cells: aid or hindrance in the clearance of disease?

CD4⁺ CD25⁺ T regulatory cells (Tregs) are classified as a subset of T cells whose role is the suppression and regulation of immune responses to self and non-self. Since their discovery in the early 1970s, the role of CD4⁺ CD25⁺ Tregs in both autoimmune and infectious disease has continued to expand. This review exam-ines the recent advances on the role CD4⁺ CD25⁺ Tregs may be playing in various diseases regarding pro-gression or protection. In addition, advances made in the purification and manipulation of CD4⁺ CD25⁺ Tregs using new cell markers, techniques and antibodies are discussed. Ultimately, an overall understanding of the exact mechanism which CD4⁺ CD25⁺ Tregs implement during disease progression will enhance our ability to manipulate CD4⁺ CD25⁺ Tregs in a clinically beneficial manner.

De novo production of K-alpha1 tubulin-specific antibodies: role in chronic lung allograft rejection

Lung transplantation is the treatment option for a variety of end-stage pulmonary diseases. Posttransplant development of Abs against donor HLA and non-HLA Ags have been associated with acute and chronic rejection of transplanted organs. Development of bronchiolitis obliterans syndrome (BOS) following lung transplantation has been correlated with de novo production of anti-donor-HLA Abs. However, only a portion of the patients with BOS demonstrate detectable anti-donor-HLA Abs. Airway epithelium is considered as a major target for lung allograft rejection. In this study we demonstrate that many BOS(+) patients (12 of 36) develop Abs reactive to epithelial cell Ag that are distinct from HLA. Furthermore, de novo production of antiepithelial cell Ab precedes clinical onset of BOS. N-terminal sequencing and blastx analysis as well as blocking with K-alpha1 tubulin-specific Ab identified the epithelial Ag as K-alpha1 tubulin. Binding of the de novo-produced anti-K-alpha1 tubulin Abs to the airway epithelial cells resulted in the increased expression of transcription factors (TCF5 and c-Myc), leading to increased expression of fibrogenic growth factors, activation of cell cycle signaling, and fibroproliferation, the central events in immunopathogenesis of BOS following human lung transplantation.

IL-17-dependent cellular immunity to collagen type V predisposes to obliterative bronchiolitis in human lung transplants

Bronchiolitis obliterans syndrome (BOS), a process of fibro-obliterative occlusion of the small airways in the transplanted lung, is the most common cause of lung transplant failure. We tested the role of cell-mediated immunity to collagen type V [col(V)] in this process. PBMC responses to col(II) and col(V) were monitored prospectively over a 7-year period. PBMCs from lung transplant recipients, but not from healthy controls or col(IV)-reactive Goodpasture's syndrome patients after renal transplant, were frequently col(V) reactive. Col(V)-specific responses were dependent on both CD4+ T cells and monocytes and required both IL-17 and the monokines TNF-alpha and IL-1beta. Strong col(V)-specific responses were associated with substantially increased incidence and severity of BOS. Incidences of acute rejection, HLA-DR mismatched transplants, and induction of HLA-specific antibodies in the transplant recipient were not as strongly associated with a risk of BOS. These data suggest that while alloimmunity initiates lung transplant rejection, de novo autoimmunity mediated by col(V)-specific Th17 cells and monocyte/macrophage accessory cells ultimately causes progressive airway obliteration.

Induction of transplantation tolerance by allogeneic donor-derived CD4(+)CD25(+)Foxp3(+) regulatory T cells

Several studies have shown that recipient-derived CD4(+)CD25(+)Foxp3(+) regulatory T cells (Tregs) are involved in transplantation tolerance. However, it is not clear whether allogeneic donor-derived Tregs are able to regulate T cell alloreactivity after solid organ allograft transplantation. Related studies in experimental bone marrow transplantation have shown that allogeneic donor-derived Tregs are capable of promoting early and long-term allogeneic hematopoietic engraftment, accompanied by tolerance to donor and recipient antigens. However, in these models, donor-derived Tregs are syngeneic with respect to the T responder cells. The role of Tregs in solid organ transplantation models where recipient-derived T responder and donor-derived Tregs are allogeneic has been scarcely studied. In order to determine whether allogeneic Tregs were able to regulate T cell alloreactivity, CD4(+)CD25(-) and CD8(+) T responder cells were cultured with stimulator dendritic cells in several responder-stimulator strain combinations (C57BL/6-->BALB/c, BALB/c-->C57BL/6 and C3H-->BALB/c) in the presence of responder-derived, stimulator-derived or 3rd-party-derived Tregs. Then, the frequency of IFN-gamma+ alloreactive T cells was determined by means of ELISPOT assay. The results of this study demonstrate that, regardless of the responder-stimulator strain combination, both responder-derived and stimulator-derived Tregs, but not 3rd-party-derived Tregs, significantly inhibited CD4(+) and CD8(+) T cell alloreactivity. The effect of allogeneic stimulator-derived Tregs was dependent on IL-10 and TGF-beta and reversed by exogenous IL-2. In vivo experiments in nu/nu recipients reconstituted with CD4(+)CD25(-) T responder and Tregs showed that recipient and donor-derived, but not 3rd-party-derived Tregs, significantly enhanced skin allograft survival. Importantly, T cells from both recipient-derived and donor-derived Treg-reconstituted nu/nu recipients exhibited donor-specific unresponsiveness in vitro. These results show that allogeneic donor-derived Tregs significantly inhibit T cell alloreactivity and suggest their potential use in the induction of transplantation tolerance.

Th-17, monokines, collagen type V, and primary graft dysfunction in lung transplantation

RATIONALE

The pathogenesis of primary graft dysfunction (PGD), a serious complication of lung transplantation, is poorly understood. Human studies and rodent models have shown that collagen type V (col[V]), stimulates IL-17-dependent cellular immunity after lung transplantation.

OBJECTIVES

To determine whether patients with end-stage lung disease develop pretransplant col(V)-specific cellular immunity, and if so, the impact of this response on PGD.

METHODS

Trans-vivo delayed-type hypersensitivity (TV-DTH) assays were used to evaluate memory T-cell responses to col(V) in 55 patients awaiting lung transplantation. Pa(O(2))/Fi(O(2)) index data were used to assess PGD. Univariate risk factor analysis was performed to identify variables associated with PGD. Rats immunized with col(V) or irrelevant antigen underwent lung isografting to determine if prior anti-col(V) immunity triggers PGD in the absence of alloreactivity.

MEASUREMENTS AND MAIN RESULTS

We found that 58.8% (10/17) of patients with idiopathic pulmonary fibrosis, and 15.8% (6/38) of patients without idiopathic pulmonary fibrosis tested while on the wait list for a lung transplant were col(V) DTH positive. Col(V) reactivity was CD4(+) T-cell and monocyte mediated, and dependent on IL-17, IL-1beta, and tumor necrosis factor (TNF)-alpha. Pa(O(2))/Fi(O(2)) indices were impaired significantly 6-72 hours after transplantation in col(V)-reactive versus nonreactive patients. Univariate risk factor analysis identified only preoperative TV-DTH to col(V) and ischemic time as predictors of PGD. Finally, in a rat lung isograft model, col(V) sensitization resulted in significantly lower Pa(O(2))/Fi(O(2)), increased local TNF-alpha and IL-1beta production, and a moderate-to-severe bronchiolitis/vasculitis when compared with control isografts.

CONCLUSIONS

The data suggest that activation of innate immunity by col(V)-specific Th-17 memory cells represents a novel pathway to PGD after lung transplantation.

Allopeptides and the alloimmune response

The inherent ability of the host immune system to distinguish between self- and non-self forms the basis of allorecognition. T lymphocytes constitute the most important effector arm of allorecognition. Here we describe the fundamentals of direct and indirect pathways by which allopeptides are presented to effector T cells. The nature of allopeptides presented along with tolerogenic strategies like altered peptide ligands and intra- or extra-thymic allopeptide inoculation are discussed. In addition, we speculate on the potential of regulatory T cells to modulate alloimmune responses.

Absence of regulatory T-cell control of TH1 and TH17 cells is responsible for the autoimmune-mediated pathology in chronic graft-versus-host disease

Graft-versus-host disease (GVHD) remains the major complication after allogeneic bone marrow transplantation (BMT). The process whereby acute GVHD mediated by alloreactive donor T cells transitions into chronic GVHD, which is characterized by prominent features of auto-immunity, has long been unresolved. In this study, we demonstrate that GVHD-associated autoimmunity and, by extension, chronic GVHD is attributable to the progressive loss of CD4(+)CD25(+)Foxp3(+) regulatory T cells during the course of acute GVHD. This leads to the expansion of donor-derived CD4(+) T cells with T(H)1 and T(H)17 cytokine phenotypes that release proinflammatory cytokines and cause autoimmune-mediated pathological damage. These T cells are present early after transplantation, indicating that the pathophysiological events that lead to chronic GVHD are set in motion during the acute phase of GVHD. We conclude that the absence of CD4(+)CD25(+) regulatory T cells coupled with unregulated T(H)1 and T(H)17 cells leads to the development of autoimmunity and that donor-derived T(H)1 and T(H)17 cells serve as the nexus between acute and chronic GVHD.

Nasal tolerance with collagen v protein reverts bronchovascular axis remodeling in experimental bronchiolitis obliterans

INTRODUCTION

The precise role of the remodeling process and possible therapies for bronchiolitis obliterans remain to be established.

OBJECTIVE

[corrected] In the present study, we sought to validate the importance of nasal collagen V tolerance to verify whether bronchovascular axis remodeling could be reverted by this therapeutic approach when compared to steroid treatment.

METHODS

Mice were randomly divided into 4 groups: control, bronchiolitis obliterans, collagen V tolerance, and prednisone groups. Morphometry was employed to evaluate bronchovascular axis dimensions, collagen density, and immune cell response. Collagen V nasal tolerance and steroid-treated mice showed significantly lower values of terminal bronchiole wall thickness and reduction in peribronchovascular cells; bronchioalveolar lymphoid tissue; and CD3+, CD4+, CD8+, and CD20+ lymphocytes. A significant decrease in CD68+ macrophage density was found in prednisone-treated mice. In addition, a strong quantitative relationship was found between collagen V tolerance, and reduction in density of immune cells and collagen.

RESULTS

Our results indicate that bronchovascular axis remodeling in bronchiolitis obliterans can be reverted by collagen V nasal tolerance, possibly as the result of T-cell suppression.

CONCLUSION

We concluded that the tolerance effects in this model were strongly related to the improvement in bronchovascular remodeling, and these may be an appropriate targets for further prospective studies on nasal collagen V tolerance.

Metalloproteinase Inhibition Has Differential Effects on Alloimmunity, Autoimmunity, and Histopathology in the Transplanted Lung

BACKGROUND

Upregulation of matrix metalloproteinases (MMPs) has been associated with chronic lung allograft rejection known as bronchiolitis obliterans syndrome. It has been suggested that MMP inhibition could prevent the rejection response. However, the effect of MMP inhibition on lung allograft rejection has not been reported.

METHODS

Utilizing a rat model of lung transplantation, tissue inhibitors of metalloproteinases (TIMP-1 and TIMP-2) were overexpressed by gene therapy in F344 rat lung allografts prior to transplantation into WKY recipient rats. Separately, WKY rats that received F344 lung allografts were treated systemically with COL-3, a global MMP inhibitor.

RESULTS

TIMP-1 and TIMP-2 had differential effects on delayed type hypersensitivity (DTH) responses to donor antigens and type V collagen, an autoantigen involved in the rejection response. Neither TIMP-1 or TIMP-2 affected the onset of rejection pathology. COL-3 suppressed DTH responses to donor antigens and type V collagen, abrogated local production of tumor necrosis factor-alpha, and interleukin-1beta. Although it did not prevent rejection pathology, COL-3 (30 mg/kg) induced intragraft B cell hyperplasia suggestive of posttransplant proliferative disorder (PTLD).

CONCLUSIONS

These data identify a complex role for MMPs and TIMPs in the immunopathogenesis of lung allograft rejection, and indicate their effects are not limited to matrix remodeling.

Early Posttransplant Inflammation Promotes the Development of Alloimmunity and Chronic Human Lung Allograft Rejection

BACKGROUND

Chronic human lung allograft rejection, represented by bronchiolitis obliterans syndrome (BOS), is the single most important factor that limits the long-term survival following lung transplantation (LT). However, the pathogenesis of BOS remains unclear. We hypothesized that the early posttransplant inflammation would promote the development of donor anti-human leukocyte antigen (HLA) alloimmunity and predispose to BOS.

METHODS

Serum levels of interleukin (IL)-1beta, IL-2, IL-4, IL-5, IL-6, IL-7, IL-8, IL-10, IL-12, IL-13, IL-15, IL-17, Eotaxin, IP-10, MIG, MCP-1, MIP-1alpha, MIP-1beta, RANTES, tumor necrosis factor (TNF)-alpha, interferon (IFN)-alpha, IFN-gamma, granulocyte-macrophage colony-stimulating factor, IL-1Ralpha, and IL-2R were serially analyzed in 31 BOS+ and matched 31 BOS- patients using quantitative multiplex bead immunoassays. Donor-specific HLA class II cellular immunity was analyzed using enzyme-linked immunospot (ELISPOT) by testing recipient peripheral blood mononuclear cells against mismatched donor HLA-DR peptides. Anti-HLA class II antibodies were monitored using flow panel reactive antibodies.

RESULTS

There was early posttransplant elevation in basal serum levels of proinflammatory chemokines IP-10 and MCP-1 and Th1-cytokines IL-1beta, IL-2, IL-12, and IL-15 in BOS+ patients, compared to BOS- and normal subjects. In addition, a threefold decline in IL-10 levels was found during BOS development. BOS+ patients revealed increased development of HLA class II alloantibodies and Th1-predominant donor-specific cellular immunity with high frequency of IFN-gamma and low IL-5 producing T-cells.

CONCLUSION

Early posttransplant elevation of proinflammatory mediators is associated with alloimmunity and chronic human lung allograft rejection.

Elevated Soluble CD30 Correlates with Development of Bronchiolitis Obliterans Syndrome Following Lung Transplantation

BACKGROUND

The long-term function of lung transplants is limited by chronic rejection (bronchiolitis obliterans syndrome, BOS). Due to lack of specific markers, BOS is diagnosed clinically. Because there is strong evidence that alloimmunity plays a significant role in the pathogenesis of BOS, we investigated whether soluble CD30 (sCD30), a T-cell activation marker, would correlate with BOS.

METHODS

Sera collected serially from BOS+ (n = 20) and matched BOS- (n = 20) lung transplant (LT) patients were analyzed for sCD30 by enzyme-linked immunosorbent assay. Pretransplant sera and sera from normal donors were also analyzed.

RESULTS

PreLT levels were comparable to normal subjects. However, posttransplant there was a significant elevation in sCD30 levels during BOS development in all BOS+ patients, compared to BOS- (mean 139.8+/-10.7 vs. 14.8+/-2.7 U/ml, P < 0.001). sCD30 levels declined in the BOS+ patients but were still elevated compared to BOS- (48.52+/-5.04 vs. 7.19+/-2.9, P < 0.0001).

CONCLUSIONS

We conclude that sCD30 may represent a novel marker to monitor the development of BOS.

Impact of immediate primary lung allograft dysfunction on bronchiolitis obliterans syndrome

RATIONALE

Primary graft dysfunction is a common complication after lung transplantation and a significant risk factor for short- and long-term mortality.

OBJECTIVE

We examined the impact of primary graft dysfunction on bronchiolitis obliterans syndrome.

METHODS

We performed a retrospective cohort study of 334 adult lung transplant recipients at our program and graded the severity of primary graft dysfunction according to the International Society for Heart and Lung Transplantation definition. We evaluated the impact of primary graft dysfunction on acute rejection, lymphocytic bronchitis, and bronchiolitis obliterans syndrome stage 1, using univariable and multivariable Cox proportional hazards models.

MAIN RESULTS

Among the 334 recipients, 65 did not have primary graft dysfunction (grade 0), 130 had grade 1, 69 had grade 2, and 70 had grade 3. In the univariable analysis, all grades of primary graft dysfunction were associated with a significantly increased risk of bronchiolitis obliterans syndrome stage 1 (grade 1: relative risk [RR] = 1.73; grade 2: RR = 2.13; and grade 3: RR = 2.53, compared with grade 0). The multivariable model demonstrated that the increased risk of bronchiolitis obliterans syndrome associated with primary graft dysfunction was independent of acute rejection, lymphocytic bronchitis, and community-acquired respiratory viral infections. However, there was no association between primary graft dysfunction and acute rejection or lymphocytic bronchitis.

CONCLUSIONS

Primary graft dysfunction is associated with an increased risk of bronchiolitis obliterans syndrome independent of acute rejection, lymphocytic bronchitis, and community-acquired respiratory viral infections, and this risk is directly related to the severity of primary graft dysfunction.