Differential Rates of Apoptosis in Bronchoalveolar Lavage and Blood of Lung Transplant Patients

Donor Club Cell Secretory Protein G38A Polymorphism Is Associated With a Decreased Risk of Primary Graft Dysfunction in the French Cohort in Lung Transplantation

BACKGROUND

Club Cell Secretory Protein (CCSP) G38A polymorphism has recently been involved in lung epithelial susceptibility to external injuries. Lung transplantation (LT) is currently limited by ischemia-reperfusion injury leading to primary graft dysfunction (PGD). We thus hypothesized that donor CCSP G38A polymorphism might impact the risk of PGD after LT.

METHODS

We focused on LT included in the French multicentric Cohort in Lung Transplantation (COLT), performed between January 2009 and December 2014, and associated with preoperative blood samples from the donor and the recipient. Characteristics of the donors, recipients, procedures, early and late outcomes were prospectively recorded in COLT. The CCSP serum concentration and CCSP gene G38A polymorphism were retrospectively determined in a blind manner. Their association with grade 3 PGD was studied in univariate and multivariate analysis.

RESULTS

The study group included 104 LT donors and recipients, 84 with grade 0 to 2 PGD and 20 with grade 3 PGD. Preoperative CCSP serum concentration was significantly higher in the donors (median, 22.54 ng/mL; interquartile range, 9.6-43.9) than in the recipients (median, 7.03 ng/mL; interquartile range, 0.89-19.2; P < 0.001) but none impacted the risk of grade 3 PGD (P = 0.93 and P = 0.69, respectively). Donor CCSP G38A polymorphism was associated with a decreased risk of grade 3 PGD in univariate (AG + AA 3/21 = 14.2% vs GG 10/26 = 38.4%, P = 0.044) and multivariate analysis (odds ratio associated with AG + AA, 0.22; 95% confidence interval, 0.041-0.88; P = 0.045), but recipient CCSP G38A polymorphism was not.

CONCLUSIONS

Donor CCSP G38A polymorphism is associated with a decreased risk of severe PGD after LT in the COLT study. These findings should be confirmed in the frame of a prospective study.

Adverse effects of immunosuppressant drugs upon airway epithelial cell and mucociliary clearance: implications for lung transplant recipients

Optimal post-transplantation immunosuppression is critical to the survival of the graft and the patient after lung transplantation. Immunosuppressant agents target various aspects of the immune system to maximize graft tolerance while minimizing medication toxicities and side effects. The vast majority of patients receive maintenance immunosuppressive therapy consisting of a triple-drug regimen including a calcineurin inhibitor, a cell cycle inhibitor and a corticosteroid. Although these immunosuppressant drugs are frequently used after transplantation and to control inflammatory processes, limited data are available with regard to their effects on cells other than those from the immunological system. Notably, the airway epithelial cell is of interest because it may contribute to development of bronchiolitis obliterans through production of pro-inflammatory cytokines. This review focuses the current armamentarium of immunosuppressant drugs used after lung transplantation and their main side effects upon airway epithelial cells and mucociliary clearance.

Altered sputum granzyme B and granzyme B/proteinase inhibitor-9 in patients with non-eosinophilic asthma

BACKGROUND AND OBJECTIVE

The non-eosinophilic phenotype of asthma (NEA) is associated with chronic airway inflammation and airway neutrophilia. An accumulation of apoptotic airway epithelial cells, if not efficiently cleared by efferocytosis, can undergo secondary necrosis, with the potential for inflammation of surrounding tissues. Apoptosis may occur via the T cell granzyme B pathway. The role of granzyme B in NEA is not known. The aim of this study was to investigate production of granzyme B and its inhibitor proteinase inhibitor (PI)-9 by T cells from induced sputum and compare expression between eosinophilic, NEA and healthy controls.

METHODS

We investigated T cell intracellular granzyme B and its inhibitor, PI-9, in sputum from healthy control subjects (n = 10), and patients with NEA (n = 22) or eosinophilic asthma (EA) (n = 15) using flow cytometry.

RESULTS

Granzyme B expression and the ratio of granzyme B to PI-9 positive cells were highest in those with NEA for both CD3+ and CD4+ T cells. The expression of granzyme B was not statistically different between patients with NEA and EA; however, the ratio of granzyme B to PI-9 positive cells for CD3+ T cells was significantly higher in those with NEA compared with EA.

CONCLUSIONS

Induced sputum provides a non-invasive tool for investigating T cell cytotoxic mediators in the various asthma subtypes. Granzyme B expression is increased in NEA and the contribution of granzyme B to chronic inflammation requires further study.

Decreased efferocytosis and mannose binding lectin in the airway in bronchiolitis obliterans syndrome

BACKGROUND

Mannose binding lectin (MBL) is a key mediator of both innate immunity and efferocytosis (phagocytosis of apoptotic cells) in the airway. Defective efferocytosis results in a net increase in apoptotic material that can undergo secondary necrosis, leading to tissue damage and chronic inflammation. We have shown reduced MBL and efferocytosis in other chronic inflammatory lung diseases; we therefore hypothesized that reduced MBL and efferocytosis in the airways may be a determinant of bronchiolitis obliterans syndrome (BOS) after lung transplantation.

METHODS

We investigated MBL (enzyme-linked immunosorbent assay [ELISA]), MBL-mediated complement deposition (UC4, ELISA), and efferocytosis of apoptotic bronchial epithelial cells (flow cytometry) in bronchoalveolar lavage (BAL) and peripheral blood from 75 lung transplant recipients, comprising 16 with stable graft function, 34 stable with proven infection, 25 with BOS, and 14 healthy controls.

RESULTS

In plasma, MBL levels were highly variable (0-17.538 μg/ml), but increased in infected patients vs control (p = 0.09) or stable groups (p = 0.003). There was a similar increase in UC4 in infected patients and a significant correlation between MBL and UC4. There was no correlation between MBL and time after transplant. In BAL, MBL levels were less variable (0-73.3 ng/ml) and significantly reduced in patients with BOS vs controls and stable groups. Efferocytosis was significantly reduced in the BOS group vs control and stable groups (mean [SEM] control, 20% [1.3%]; stable, 20.5% [2.5%]; infected, 17.3% [2.8%]; BOS, 11.3% [1.5%], p = 0.04).

CONCLUSIONS

Low levels of MBL in the airway may play a role in reduced efferocytosis, subsequent tissue damage, and BOS after lung transplantation.

Mannose-binding lectin deficiency linked to cytomegalovirus (CMV) reactivation and survival in lung transplantation

Despite the use of immunosuppressives mainly influencing T and B cell responses, the prevalence of the bronchiolitis obliterans syndrome (BOS) after lung transplantation is high. Mannose-binding lectin (MBL) is a pattern recognition molecule of complement and an important component of the innate immunity. MBL is associated with rejection, infection and survival in other solid organ transplantations. In this study the relation between functional MBL levels and cytomegalovirus (CMV) reactivations and the development of BOS and survival after lung transplantation was investigated. MBL levels were measured in 85 patients before and in 57 of these patients after lung transplantation. The relation of MBL on survival, CMV reactivation and the development of BOS were investigated with Kaplan-Meier (log-rank) survival analysis. MBL levels decreased on average by 20% (P < 0·001) after transplantation and eventually returned to pretransplant levels. Fourteen of the 85 patients had deficient pretransplant MBL levels and these patients had a tendency towards a better survival compared to those with normal MBL levels (P = 0·08). Although no correlation was found between MBL deficiency and the development of BOS, more CMV reactivations occurred in recipients with deficient versus normal levels of MBL (P = 0·03). Our results suggest that MBL deficiency is associated with CMV reactivations and a longer overall survival, but not with the development of BOS.

Value of FOXP3 expression in peripheral blood as rejection marker after miniature swine lung transplantation

BACKGROUND

Outcome for highly immunogenic lung transplantation remains unsatisfactory despite the development of potent immunosuppressants. The poor outcome may be the result of a lack of minimally invasive methods to detect early rejection. There is emerging clinical evidence that, paradoxically, expression of forkhead box P3 (FOXP3, a specific marker for the regulatory T cells) is upregulated within rejecting grafts.

METHODS

Orthotopic lung transplantation was performed using miniature swine without immunosuppression. Rejection was monitored by chest radiography and open lung biopsy. Expressions levels of FOXP3, perforin, Fas-L and IP-10 mRNA were quantified in the peripheral blood. In addition, rescue immunosuppressive therapy (steroid plus tacrolimus) was administered on post-operative day (POD) 4 or 6.

RESULTS

Early rejection was detected by open lung biopsy, but misdiagnosed by chest radiography on POD 4. Expression of FOXP3 in the peripheral blood reached its highest value as early as POD 4, followed by a decline. Such an increase of FOXP3 was not observed in recipients given high-dose tacrolimus. Neither perforin, Fas-L or IP-10 in the peripheral blood exhibited significant fluctuations in the early phase of rejection. Rescue immunosuppressive therapy from POD 4, when peak FOXP3 was seen, prolonged graft survival (27.2 days, versus 9.1 days without immunosuppression, p < 0.001), in contrast to POD 6, when rejection was suspected by chest radiography (11.5 days, p = not statistically significant [NS]).

CONCLUSIONS

In a miniature swine lung transplantation model, the FOXP3 mRNA level in the peripheral blood was upregulated at an early phase of rejection. The clinical implication of this finding remains to be elucidated.

Posttransplant bronchiolitis obliterans syndrome is associated with bronchial epithelial to mesenchymal transition

Bronchiolitis obliterans syndrome (BOS) compromises lung transplant outcomes and is characterised by airway epithelial damage and fibrosis. The process whereby the normal epithelial configuration is replaced by fibroblastic scar tissue is poorly understood, but recent studies have implicated epithelial mesenchymal transition (EMT). The primary aim of this study was to assess the utility of flow cytometry in detecting and quantifying EMT in bronchial epithelial cells. Large airway brushings were obtained at 33 bronchoscopies in 16 BOS-free and 6 BOS grade 1-3 patients at 2-120 months posttransplant. Flow cytometry was used to assess expression of the mesenchymal markers alphaSMA, S100A4 and ED-A FN and HLA-DR. TGF beta 1 and HGF were measured in Bronchoalveolar lavage (BAL). Expression of all three mesenchymal markers was increased in BOS, as was HLA-DR. BAL HGF, but not TGF beta 1 was increased in BOS. Longitudinal investigation of one patient revealed a 100% increase in EMT markers concurrent with a 6-fold increase in BAL TGF beta 1 and the diagnosis of BOS at 17 months posttransplant. Flow cytometric evaluation of bronchial epithelium may provide a novel and rapid means to assess lung allografts at risk of BOS.

Compartmentalization of intracellular proinflammatory cytokines in bronchial intraepithelial T cells of stable lung transplant patients

Allograft rejection remains a major cause of morbidity and mortality following lung transplantation and is associated with an increased expression of T cell proinflammatory cytokines. We have shown that CD4(+) T cell proinflammatory cytokine production was significantly reduced in peripheral blood and bronchoalveolar lavage (BAL) of stable lung transplant patients, consistent with immunosuppression therapy. However, analysis of inflammatory cytokine profiles of intraepithelial T cells in bronchial brushing (BB) may be more relevant than peripheral blood or BAL T cells for assessing immune graft status. To investigate the immunomodulatory effects of currently used immunosuppressive regimens on bronchial intraepithelial T cell cytokine production, whole blood, BAL and BB from stable lung transplant patients and control volunteers were stimulated in vitro and cytokine production by CD8(+) and CD4(+) T cell subsets determined using multi-parameter flow cytometry. In bronchial intraepithelial T cell subsets in control subjects and transplant patients there was compartmentalization of interferon (IFN)-gamma and tumour necrosis factor (TNF)-alpha production, a decrease in interleukin (IL)-2 production by CD4(+) T cells and CD4 : CD8 inversion compared with blood and BAL. Although there was a decrease in T cell proinflammatory cytokine production in blood of transplant patients, this was not found in BAL or bronchial intraepithelial CD8 T cell subsets, suggesting that the same level of immunosuppression may not occur in the lung of transplant recipients. Drugs that effectively reduce CD8 T cell proinflammatory cytokine production in the lung compartment may improve current protocols for reducing graft rejection in these patients.