Acute pulmonary allograft rejection. Mechanisms, diagnosis, and management

Immunosuppressive drug therapy for preventing rejection following lung transplantation in cystic fibrosis

BACKGROUND

For people with cystic fibrosis and advanced pulmonary damage, lung transplantation is an available and viable option. However, graft rejection is an important potential consequence after lung transplantation. Immunosuppressive therapy is needed to prevent episodes of graft rejection and thus subsequently reduce morbidity and mortality in this population. There are a number of classes of immunosuppressive drugs which act on different components of the immune system. There is considerable variability in the use of immunosuppressive agents after lung transplantation in cystic fibrosis. While much of the research in immunosuppressive drug therapy has focused on the general population of lung transplant recipients, little is known about the comparative effectiveness and safety of these agents in people with cystic fibrosis. This is an update of a previously published review.

OBJECTIVES

To assess the effects of individual drugs or combinations of drugs compared to placebo or other individual drugs or combinations of drugs in preventing rejection following lung transplantation in people with cystic fibrosis.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register and scanned references of the potentially eligible study. We also searched the www.clinicaltrials.gov registry and the World Health Organisation (WHO) International Clinical Trials Registry Platform (ICTRP) to obtain information on unpublished and ongoing studies.Date of latest search: 29 May 2018.

SELECTION CRITERIA

Randomised and quasi-randomised studies.

DATA COLLECTION AND ANALYSIS

We independently assessed the studies identified from our searches for inclusion in the review. Should eligible studies be identified and included in future updates of the review, we will independently extract data and assess the risk of bias. We will use GRADE to summarize our results through a summary of findings table for each comparison we present in the review.

MAIN RESULTS

While five studies addressed the interventions of interest, we did not include them in the review because the investigators of the studies did not report any information specific to people with cystic fibrosis. Our attempts to obtain this information have not yet been successful. We will include any provided data in future updates of the review.

AUTHORS' CONCLUSIONS

The lack of currently available evidence makes it impossible to draw conclusions about the comparative efficacy and safety of the various immunosuppressive drugs among people with cystic fibrosis after lung transplantation. A 2013 Cochrane Review comparing tacrolimus with cyclosporine in all lung transplant recipients (not restricted to those with cystic fibrosis) reported no significant difference in mortality and risk of acute rejection. However, tacrolimus use was associated with lower risk of broncholitis obliterans syndrome and arterial hypertension and higher risk of diabetes mellitus. It should be noted that this wider review contained only a small number of included studies (n = 3) with a high risk of bias. Additional randomised studies are required to provide evidence for the benefit and safety of the use of immunosuppressive therapy among people with cystic fibrosis after lung transplantation.

Imaging of Lung Transplantation

Lung transplantation has become a viable treatment option for end-stage lung disease. Common indications for lung transplantation are chronic obstructive pulmonary disease (COPD), idiopathic pulmonary fibrosis, cystic fibrosis, alpha-1 antitrypsin deficiency, and pulmonary arterial hypertension. Either single or bilateral lung transplantation can be performed, but bilateral lung recipients appear to have a better median survival than single lung recipients. Complications after lung transplantation are common and may have nonspecific clinical and radiologic manifestations. The time point at which these complications occur relative to the date of transplant is crucial in formulating a differential diagnosis and recognizing them accurately. Significant advances in imaging techniques and recognition of air trapping in exhalation images and other patterns /distribution of parenchymal abnormalities have led to routine use of HRCT for diagnostic evaluation in patients manifesting respiratory decline in the lung transplant recipient.

Diagnostic value of plasma and bronchoalveolar lavage samples in acute lung allograft rejection: differential cytology

Diagnosis of acute lung allograft rejection is currently based on transbronchial lung biopsies. Additional methods to detect acute allograft dysfunction derived from plasma and bronchoalveolar lavage samples might facilitate diagnosis and ultimately improve allograft survival. This review article gives an overview of the cell profiles of bronchoalveolar lavage and plasma samples during acute lung allograft rejection. The value of these cells and changes within the pattern of differential cytology to support the diagnosis of acute lung allograft rejection is discussed. Current findings on the topic are highlighted and trends for future research are identified.

What can happen after lung transplantation and the importance of the time since transplantation: radiological review of post-transplantation complications

Lung transplantation is the best treatment option in the final stages of diseases such as cystic fibrosis, pulmonary hypertension, chronic obstructive pulmonary disease, or idiopathic pulmonary fibrosis. Better surgical techniques and advances in immunosuppressor treatments have increased survival in lung transplant recipients, making longer follow-up necessary because complications can occur at any time after transplantation. For practical purposes, complications can be classified as early (those that normally occur within two months after transplantation), late (those that normally occur more than two months after transplantation), or time-independent (those that can occur at any time after transplantation). Many complications have nonspecific clinical and radiological manifestations, so the time factor is key to narrow the differential diagnosis. Imaging can guide interventional procedures and can detect complications early. This article aims to describe and illustrate the complications that can occur after lung transplantation from the clinical and radiological viewpoints so that they can be detected as early as possible.

Immunosuppressive drug therapy for preventing rejection following lung transplantation in cystic fibrosis

BACKGROUND

For people with cystic fibrosis and advanced pulmonary damage, lung transplantation is an available and viable option. However, graft rejection is an important potential consequence after lung transplantation. Immunosuppressive therapy is needed to prevent episodes of graft rejection and thus subsequently reduce morbidity and mortality in this population. There are a number of classes of immunosuppressive drugs which act on different components of the immune system. There is considerable variability in the use of immunosuppressive agents after lung transplantation in cystic fibrosis. While much of the research in immunosuppressive drug therapy has focused on the general population of lung transplant recipients, little is known about the comparative effectiveness and safety of these agents in people with cystic fibrosis. This is an update of a previously published review.

OBJECTIVES

To assess the effects of individual drugs or combinations of drugs compared to placebo or other individual drugs or combinations of drugs in preventing rejection following lung transplantation in people with cystic fibrosis.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register and scanned references of the potentially eligible study. We also searched the www.clinicaltrials.gov registry to obtain information on unpublished and ongoing studies.Date of latest search: 19 May 2015.

SELECTION CRITERIA

Randomised and quasi-randomised studies.

DATA COLLECTION AND ANALYSIS

We independently assessed the studies identified from our searches for inclusion in the review. Should eligible studies be identified and included in future updates of the review, we will independently extract data and assess the risk of bias.

MAIN RESULTS

While two studies met our inclusion criteria, we did not include them in the review because the investigators of the studies did not report any information specific to people with cystic fibrosis. Our attempts to obtain this information have not yet been successful. We will include any provided data in future updates of the review.

AUTHORS' CONCLUSIONS

The lack of currently available evidence makes it impossible to draw conclusions about the comparative efficacy and safety of the various immunosuppressive drugs among people with cystic fibrosis after lung transplantation. A recent Cochrane review comparing tacrolimus with cyclosporine in all lung transplant recipients (not restricted to those with cystic fibrosis) reported no significant difference in mortality and risk of acute rejection. However, tacrolimus use was associated with lower risk of broncholitis obliterans syndrome and arterial hypertension and higher risk of diabetes mellitus. It should be noted that this wider review contained only a small number of included studies (n = 3) with a high risk of bias. Additional randomised studies are required to provide evidence for the benefit and safety of the use of immunosuppressive therapy among people with cystic fibrosis after lung transplantation.

Imaging in lung transplants: Checklist for the radiologist

Post lung transplant complications can have overlapping clinical and imaging features, and hence, the time point at which they occur is a key distinguisher. Complications of lung transplantation may occur along a continuum in the immediate or longer postoperative period, including surgical and mechanical problems due to size mismatch and vascular as well as airway anastomotic complication, injuries from ischemia and reperfusion, acute and chronic rejection, pulmonary infections, and post-transplantation lymphoproliferative disorder. Life expectancy after lung transplantation has been limited primarily by chronic rejection and infection. Multiple detector computed tomography (MDCT) is critical for evaluation and early diagnosis of complications to enable selection of effective therapy and decrease morbidity and mortality among lung transplant recipients.

Immunosuppressive drug therapy for preventing rejection following lung transplantation in cystic fibrosis

BACKGROUND

For patients with cystic fibrosis and advanced pulmonary damage, lung transplantation is an available and viable option. However, graft rejection is an important potential consequence after lung transplantation. Immunosuppressive therapy is needed to prevent episodes of graft rejection and thus subsequently reduce morbidity and mortality in this population. There are a number of classes of immunosuppressive drugs which act on different components of the immune system. There is considerable variability in the use of immunosuppressive agents after lung transplantation in cystic fibrosis. While much of the research in immunosuppressive drug therapy has focused on the general population of lung transplant recipients, little is known about the comparative effectiveness and safety of these agents in patients with cystic fibrosis.

OBJECTIVES

To assess the effects of individual drugs or combinations of drugs compared to placebo or other individual drugs or combinations of drugs in preventing rejection following lung transplantation in patients with cystic fibrosis.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register and scanned references of the potentially eligible study. We also searched the www.clinicaltrials.gov trials registry to obtain information on unpublished and ongoing studies.Date of latest search: 22 August 2013.

SELECTION CRITERIA

Randomised and quasi-randomised studies.

DATA COLLECTION AND ANALYSIS

We independently assessed the studies identified from our searches for inclusion in the review. Should eligible studies be identified and included in future updates of the review, we will independently extract data and assess the risk of bias.

MAIN RESULTS

While two studies met our inclusion criteria, we did not include them in the review because the investigators of the studies did not report any information specific to patients with cystic fibrosis. Our attempts to obtain this information have not yet been successful. We will include any provided data in future updates of the review.

AUTHORS' CONCLUSIONS

The lack of currently available evidence makes it impossible to make conclusions about the comparative efficacy and safety of the various immunosuppressive drugs among patients with cystic fibrosis after lung transplantation. A recent Cochrane review comparing tacrolimus with cyclosporine in all patients with lung transplantation (not restricted to patients with cystic fibrosis) reported no significant difference in mortality and risk of acute rejection. However, tacrolimus use was associated with lower risk of broncholitis obliterans syndrome and arterial hypertension and higher risk of diabetes mellitus. It should be noted that this review contained only a small number of included studies (n = 3) with a high risk of bias. Additional randomised studies are required to provide evidence for the benefit and safety of the use of immunosuppressive therapy among patients with cystic fibrosis after lung transplantation.

Computed tomography findings of postoperative complications in lung transplantation

Due to the increasing number and improved survival of lung transplant recipients, radiologists should be aware of the imaging features of the postoperative complications that can occur in such patients. The early treatment of complications is important for the long-term survival of lung transplant recipients. Frequently, HRCT plays a central role in the investigation of such complications. Early recognition of the signs of complications allows treatment to be initiated earlier, which improves survival. The aim of this pictorial review was to demonstrate the CT scan appearance of pulmonary complications such as reperfusion edema, acute rejection, infection, pulmonary thromboembolism, chronic rejection, bronchiolitis obliterans syndrome, cryptogenic organizing pneumonia, post-transplant lymphoproliferative disorder, bronchial dehiscence and bronchial stenosis.

Postoperative complications of lung transplantation: radiologic findings along a time continuum

In the past decade, lung transplantation has become established as an accepted therapy for end-stage pulmonary disease. Complications of lung transplantation that may occur in the immediate or longer postoperative term include mechanical problems due to a size mismatch between the donor lung and the recipient thoracic cage; malposition of monitoring tubes and lines; injuries from ischemia and reperfusion; acute pleural events; hyperacute, acute, and chronic rejection; pulmonary infections; bronchial anastomotic complications; pulmonary thromboembolism; upper-lobe fibrosis; primary disease recurrence; posttransplantation lymphoproliferative disorder; and native lung complications such as hyperinflation, malignancy, and infection. Radiologic imaging--particularly chest radiography, computed tomography (CT), and high-resolution CT--is critical for the early detection, evaluation, and diagnosis of complications after lung transplantation. To enable the selection of an effective and relevant course of therapy and, ultimately, to decrease morbidity and mortality among lung transplant recipients, radiologists at all levels of experience must be able to recognize and understand the imaging manifestations of posttransplantation complications.

Bronchoalveolar lavage fluid characteristics in acute and chronic lung transplant rejection

BACKGROUND

The detection of graft rejection by bronchoalveolar lavage remains controversial.

METHODS

To assess the value of bronchoalveolar lavage fluid in acute and chronic rejection after lung transplantation we analyzed bronchoalveolar lavage fluid cellular differential characteristics, lymphocyte sub-types and interleukin-6 (IL-6) and interleukin-8 (IL-8) cytokine levels in patients with exclusively either acute rejection (n = 37) or bronchiolitis obliterans (BO; n = 48). Both groups were compared with a control group of lung transplantation patients without rejection or infection, matched for the time the lavage was performed after lung transplantation.

RESULTS

The bronchiolitis obliterans group showed marked neutrophilia, high IL-8 and higher CD4(+)CD25(+) and CD8(+)CD45(+) bronchoalveolar lavage fluid levels when compared with their stable controls. When using a cut-off point of >3% neutrophils in the lavage, the sensitivity for BO is 87.0%, the specificity 77.6%. The sensitivity of IL-8 for BO when using a cut-off point of >71.4 pg/ml is 74.5%, the specificity 83.3%. Bronchoalveolar lavage fluid in acute rejection was characterized by marked lymphocytosis, but showed no difference when compared with stable controls in any of the lymphocyte sub-types studied. When using a cut-off point of <==1% lymphocytes in the lavage, the sensitivity for acute rejection (AR) is 40.4%, the specificity 95.6%. The marked neutrophilia, high IL-8 cytokine level and more activated lymphocyte population in bronchiolitis obliterans may indicate ongoing local allograft rejection.

CONCLUSIONS

In the present study we were not able to show any difference in lymphocyte sub-types when comparing acute rejection and control subjects. Cellular and soluble parameters in bronchoalveolar lavage fluid appear useful for diagnosing bronchiolitis obliterans.

Gene expression profiling of bronchoalveolar lavage cells in acute lung rejection

Lung transplantation is effective for many diseases that are unresponsive to other therapy. However, long-term survival of recipients is limited by the development of bronchiolitis obliterans syndrome. Acute rejection is a major risk factor for bronchiolitis obliterans syndrome, but noninvasive biomarkers have not been identified. To address this deficiency, gene expression microarrays were performed using bronchoalveolar lavage cells of lung transplant recipients with acute rejection (n = 7) and with no rejection (n = 27). The cell and differential counts were similar. Signal values for genes between groups were compared using t tests. One hundred thirty-five genes were upregulated in the acute-rejection group, including genes involved in acute rejection, immune response genes with an unknown role in rejection, genes not known to have a role in rejection, and genes of unknown function. Two-dimensional hierarchical clustering grouped all acute rejection samples into one cluster and the majority of the no-rejection samples into a second cluster. The acute-rejection samples showed significant changes in gene expression for seven biological pathways. Bronchoalveolar lavage cells are a reliable RNA source for microarray analysis, which is powerful in identifying acute-rejection genes. The individual genes, patterns of gene expression, or biologic pathways identified may represent novel biomarkers for acute rejection.

Pattern and Predictors of Early Rejection After Lung Transplantation

• Background Most lung transplant recipients experience improvement in their underlying pulmonary condition but are faced with the threat of allograft rejection, the primary determinant of long-term survival. Several studies examined predictors of rejection, but few focused on the early period after transplantation.

• Objectives To describe the pattern and predictors of early rejection during the first year after transplantation to guide the development of interventions to facilitate earlier detection and treatment of rejection.

• Methods Data for donor, recipient, and posttransplant variables were retrieved retrospectively for 250 recipients of single or double lung transplants.

• Results Most recipients (85%) had at least 1 episode of acute rejection; 33% had a single episode; 23% had recurrent rejection; 3% had persistent rejection; 13% had refractory rejection; and 14% had clinicopathological evidence of chronic rejection. Serious rejection (refractory acute rejection or chronic rejection) developed in 27% of recipients. Compared with other recipients, recipients who had serious rejection had more episodes of acute rejection (P = .004), and the first acute episodes occurred sooner after transplantation (P = .01) and were of a higher grade (P = .002).

• Conclusions Recipients who experienced higher grades for their first episode of acute rejection (P=.03) and higher cumulative rejection scores (P = .004) were significantly more likely than other recipients to have serious rejection during the first year after transplantation.

Patterns and significance of exhaled-breath biomarkers in lung transplant recipients with acute allograft rejection

BACKGROUND

Obliterative bronchiolitis (OB) remains one of the leading causes of death in lung transplant recipients after 2 years, and acute rejection (AR) of lung allograft is a major risk factor for OB. Treatment of AR may reduce the incidence of OB, although diagnosis of AR often requires bronchoscopic lung biopsy. In this study, we evaluated the utility of exhaled-breath biomarkers for the non-invasive diagnosis of AR.

METHODS

We obtained breath samples from 44 consecutive lung transplant recipients who attended ambulatory follow-up visits for the Johns Hopkins Lung Transplant Program. Bronchoscopy within 7 days of their breath samples showed histopathology in 21 of these patients, and we included them in our analysis. We measured hydrocarbon markers of pro-oxidant events (ethane and 1-pentane), isoprene, acetone, and sulfur-containing compounds (hydrogen sulfide and carbonyl sulfide) in exhaled breath and compared their levels to the lung histopathology, graded as stable (non-rejection) or AR. None of the study subjects were diagnosed with OB or infection at the time of the clinical bronchoscopy.

RESULTS

We found no significant difference in exhaled levels of hydrocarbons, acetone, or hydrogen sulfide between the stable and AR groups. However, we did find significant increase in exhaled carbonyl sulfide (COS) levels in AR subjects compared with stable subjects. We also observed a trend in 7 of 8 patients who had serial sets of breath and histopathology data that supported a role for COS as a breath biomarker of AR.

CONCLUSIONS

This study demonstrated elevations in exhaled COS levels in subjects with AR compared with stable subjects, suggesting a diagnostic role for this non-invasive biomarker. Further exploration of breath analysis in lung transplant recipients is warranted to complement fiberoptic bronchoscopy and obviate the need for this procedure in some patients.

In the lung aerosol cyclosporine provides a regional concentration advantage over intramuscular cyclosporine

BACKGROUND

Acute rejection remains an almost universal complication among lung transplant recipients. Refractory rejection as well as chronic systemic immunosuppression is associated with significant morbidity and mortality. Recent studies suggest that aerosol cyclosporine may address these issues by effectively preventing acute cellular rejection while maintaining low systemic drug concentrations. This study was designed to evaluate the concentrations of cyclosporine in blood and lung tissue after aerosol and intramuscular administration.

METHODS

Lewis rats were divided into 4 experimental groups: Groups A (n = 33) and B (n = 30) received aerosol cyclosporine 3 and 5 mg/kg, respectively; Groups C (n = 33) and D (n = 30) received systemic cyclosporine 5 and 15 mg/kg, respectively. We used high-performance liquid chromatography to quantitate blood and lung tissue cyclosporine levels at timed intervals. We used the trapezoidal rule to approximate area under the concentration vs time curve (AUC).

RESULTS

Aerosol delivery of cyclosporine resulted in higher and more rapid peak drug levels in lung tissue samples than did systemic delivery. At an equivalent 5 mg/kg dose, the cyclosporine AUC was 3 times higher with aerosol delivery than with intramuscular delivery in lung tissue (477,965 vs 157,706 ng x hour/g, respectively). The lung tissue: blood AUC ratio was highest in the aerosol groups (27.3:1 and 17.4:1) compared with the intramuscular groups (8.1:1 and 9.4:1).

CONCLUSION

Local aerosol inhalation delivery of cyclosporine provides a regional advantage over systemic intramuscular therapy by providing higher peak concentrations and greater lung tissue exposure.

Successful treatment of acute, ongoing rat lung allograft rejection with the novel immunosuppressant SDZ-RAD

BACKGROUND

Recent experimental data have shown that coadministration of microemulsion cyclosporine and the novel immunosuppressant SDZ-RAD potentiates the immunosuppressive efficacies of both drugs to suppress allograft rejection. Our study was designed to assess the potential of delayed SDZ-RAD administration, in addition to cyclosporine maintenance therapy, to reverse acute rejection in an allogeneic rat lung transplant model.

METHODS

Unilateral left lung transplantation was performed using Brown-Norway donors implanted into Lewis recipients. An untreated control group and a cyclosporine monotherapy group (7.5 mg/kg) were followed for 7 days. An additional cyclosporine monotherapy group (7.5 mg/kg), and a combined therapy group treated with cyclosporine (7.5 mg/kg) plus SDZ-RAD (2.5 mg/kg), were followed for 21 days. For treatment of ongoing rejection, 7.5 mg/kg cyclosporine was given as maintenance therapy, and SDZ-RAD (2.5 mg/kg) was added on postoperative day 7. Drugs were given orally, and in the combined therapy regimens, administered 6 hours apart. Outcome variables included daily weight, radiographs, and histology.

RESULTS

Radiographs on postoperative day 7 showed mild and moderate opacification of the left chest in the cyclosporine monotherapy groups and the untreated control group. Addition of SDZ-RAD to cyclosporine treatment on postoperative day 7 reversed opacification by postoperative days 14 and 21. Monotherapy with microemulsion CsA resulted in mild histological rejection by day 7, which progressed to moderate rejection by day 21. Addition of SDZ-RAD on postoperative day 7 reversed acute rejection, resulting in none or minimal rejection at day 21.

CONCLUSIONS

SDZ RAD reverses acute rejection under cyclosporine maintenance therapy in a stringent lung allotransplant model.

The histology of subcutaneously implanted donor bronchial rings correlates with rejection scores of lung allografts in a primate lung transplant model

BACKGROUND

The diagnosis of acute rejection in lung transplantation generally relies on transbronchial biopsies. This invasive procedure may be associated with bronchial bleeding or pneumothorax and may not be feasible in patients with severely compromised lung function. The hypothesis of the current study was that histopathological findings of donor bronchial segments implanted into the subcutaneous tissue of lung allograft recipients would predict lung tissue rejection scores, thus providing the clinician with an alternate source of information.

METHODS

Unilateral left lung transplantation was performed in 34 cynomolgus monkeys as part of a drug efficacy study. After completion of the transplant procedure, 4 bronchial ring segments of the explanted recipient left lung and 4 bronchial ring segments of the non-transplanted right donor lung were implanted subcutaneously in the abdominal region. Lung allograft rejection was evaluated by open lung biopsies of the allograft performed on postoperative (PO) Day 14 and during sacrifice on PO Day 28. At the time of each biopsy, 2 donor and 2 recipient subcutaneous bronchial rings were explanted. Histologic evaluation of the lung tissue samples was performed according to the working formulation of the International Society for Heart and Lung Transplantation. Bronchial rings were independently evaluated by assessing the degree of airway narrowing; percentage of intact epithelial coverage as well as its specific histology (respiratory ciliated, flattened cuboidal, squamous); presence of lymphocytes, macrophages or spindle cells; and presence of peribronchial inflammation, luminal fibrosis, lymphocytic bronchitis or luminal mucous. Statistical analysis was performed by logistic regression.

RESULTS

In the recipient bronchial rings, there was no evidence of airway narrowing. There was 98% epithelial coverage, 71% that were respiratory ciliated cells, and there was no inflammation. Donor bronchial rings showed no airway narrowing for monkeys with grade A0 to A2 rejection in tissue biopsies and a maximum narrowing (41.2%) with A4 rejection. Epithelial cell coverage was approximately 100% with grade A0-A2 and 44+/-11% with A4 rejection. Lymphocytic bronchitis was most severe in A4 rejection and minimal in A0 to A2 rejection. By logistic regression analysis, independent predictors of a likelihood of rejection were the degree of airway obliteration, the percentage of epithelial cell coverage, the degree of lymphocytic bronchitis and the product of respiratory and flattened cuboidal cell coverage.

CONCLUSIONS

The current data show that histologic alterations of subcutaneously implanted donor bronchial rings correlate with lung tissue biopsy scores based on the ISHLT working formulation. Because subcutaneous bronchial rings can be explanted under local anesthesia, they may provide useful information for the diagnosis of acute allograft rejection in patients with impaired lung function, patients that obtaining lung tissue samples may not be feasible.