Respiratory viral infections are a distinct risk for bronchiolitis obliterans syndrome and death

Influenza in immunocompromised patients: considerations for therapy

Influenza infection results in substantial morbidity and mortality in immunocompromised patients, and the risks for influenza and its related complications depend on the degree of immunosuppression. In addition to influenza vaccination and infection control precautions, two classes of antiviral drugs are currently approved for treatment and prophylaxis in uncomplicated infected patients. However, there are no randomized controlled trials assessing the efficacy and safety of licensed antivirals for influenza management in immunocompromised patients. The purpose of this article is to highlight some considerations for therapy in immunocompromised patients, the usefulness of vaccination for the prevention of influenza and the clinical interest in surveillance of antiviral resistance.

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.

Respiratory viruses in lung transplant recipients: a critical review and pooled analysis of clinical studies

Lung transplant recipients present an increased risk for severe complications associated with respiratory infections. We conducted a review of the literature examining the clinical relationship between viral respiratory infection and graft complications. Thirty-four studies describing the clinical impact of influenza, respiratory syncytial virus, parainfluenza, human metapneumovirus, rhinovirus, enterovirus, coronavirus, bocavirus or adenovirus were identified. The detection rate of respiratory viral infection ranged from 1.4% to 60%. Viruses were detected five times more frequently when respiratory symptoms were present [odds ratio (OR) = 4.97; 95% CI = 2.11-11.68]. Based on available observations, we could not observe an association between respiratory viral infection and acute rejection (OR = 1.35; 95% CI = 0.41-4.43). We found a pooled incidence of 18% (9/50) of bronchiolitis obliterans syndrome (BOS) in virus-positive cases compared to 11.6% (37/319) in virus-negative cases; however, limited number of BOS events did not allow to confirm the association. Our review confirms a causal relationship between respiratory viruses and respiratory symptoms, but cannot confirm a link between respiratory viruses and acute lung rejection. This is related in part to the heterogeneity and limitations of available studies. The link with BOS needs also to be reassessed in appropriate prospective studies.

Non-tuberculous mycobacterium infection after lung transplantation is associated with increased mortality

BACKGROUND

Pulmonary non-tuberculous mycobacterial (NTM) infection is relatively common after lung transplantation, but the effect on mortality remains undetermined. Herein we describe our experience with pulmonary NTM infection after lung transplantation and hypothesized that non-tuberculous mycobacterial infection after lung transplantation would be associated with increased mortality.

METHODS

We retrospectively evaluated 201 primary lung transplant recipients transplanted between January 2000 and August 2006. Serial bronchoscopies with bronchoalveolar lavage and transbronchial biopsy were performed according to a surveillance protocol and when clinically indicated. The diagnosis NTM infection was established by a positive NTM culture in a bronchoalveolar lavage sample or in at least two separate expectorated sputum samples. NTM infections were further classified as "disease" or "colonization," based on whether or not NTM infection patients developed symptoms and characteristic radiographic findings.

RESULTS

Thirty-six (18%) recipients were diagnosed with pulmonary NTM infection at a median of 97 days post-transplantation: 9 were classified as NTM disease and the remaining 27 as NTM colonization cases. Single lung transplant was a significant risk factor for NTM infection (HR 2.25, p = 0.02). NTM colonization was a risk factor for NTM disease (HR 8.39, p = 0.003). NTM infection significantly increased the risk of death after lung transplantation (HR 2.61, p = 0.001) and persisted in multivariate models controlling for single lung transplant and bronchiolitis obliterans syndrome. The increased risk was seen for both NTM colonization and NTM disease. Among the patients who died, non-NTM infection was a more common contributing factor in the cause of death for the NTM infection group (44% vs 12%, p = 0.04).

CONCLUSIONS

Non-tuberculous mycobacterial infection is common after lung transplantation. NTM colonization and treated acute rejection are risk factors for NTM disease. NTM infection is associated with increased risk of mortality independent of bronchiolitis obliterans syndrome.

The impact of pandemic influenza A H1N1 2009 on Australian lung transplant recipients

Influenza A H1N1 2009 led to 189 deaths during the Australian pandemic. Community-acquired respiratory viruses not only can cause prolonged allograft dysfunction in lung transplant recipients but have also been linked to bronchiolitis obliterans syndrome (BOS). We report the impact of the 2009 H1N1 pandemic on Australian lung transplant recipients. An observational study of confirmed H1N1 cases was conducted across five Australian lung transplant programs during the pandemic. An electronic database collected patient demographics, clinical presentation, management and outcomes up to a year follow-up. Twenty-four H1N1 cases (mean age 43 ± 14 years, eight females) were identified, incidence of 3%. Illness severity varied from upper respiratory tract symptoms only in 29% to lung allograft dysfunction (≥10% decline FEV1) in 75% to death in 5 (21%) cases (pre-existing BOS grade 3, n = 4). Treatment with oseltamivir occurred in all but one case confirmed after death, reduced immunosuppression, n = 1, augmented corticosteroid therapy, n = 16, and mechanical/noninvasive ventilation, n = 4. There was BOS grade decline within a year in six cases (32%). In conclusion, Australian lung transplant recipients were variably affected by the H1N1 pandemic mirroring the broader community with significant morbidity and mortality. After initial recovery, a considerable proportion of survivors have demonstrated BOS progression.

Pandemic influenza A/H1N1 virus infection in solid organ transplant recipients: a multicenter study

BACKGROUND

The 2009 novel influenza A/H1N1 virus pandemic did not spare solid organ transplant (SOT) recipients. We aimed to describe the behavior of pandemic influenza infection in a group of SOT recipients in Argentina.

METHODS

Data from 10 transplant (Tx) centers were retrospectively collected for SOT that presented with a respiratory illness compatible with pandemic influenza A infection, between May and September 2009. Cases were defined as suspected, probable, or confirmed according to diagnostic method.

RESULTS

Seventy-seven cases were included. No significant differences in presenting symptoms, pulmonary infiltrates, and graft involvement were found among 35 suspected, 19 probable, and 23 confirmed cases. The 33 ambulatory cases had significantly more sore throat and headache when compared with 34 cases admitted to medical ward (MW) and 10 admitted to intensive care unit (ICU), 9 of whom required ventilatory support. MW and ICU cases had significantly more dyspnea, hypoxemia, pulmonary infiltrates, and graft dysfunction. Time from onset of symptoms to first visit and to treatment was significantly longer in MW and ICU cases (P=0.008). Coinfections were found in six cases. Most cases received oseltamivir for 5 to 10 days. Six patients (7.8%) died from viral infection at a median of 15 days from admission. No differences in outcome were seen related to the transplanted organ, the immunosuppressive regimen, time from Tx, or confirmation of diagnosis.

CONCLUSIONS

Mortality is higher in Tx recipients than in the general population. Poor outcome seems to be related to a delay in the beginning of treatment.

Challenges in the diagnosis of 2009 H1N1 in a lung transplant patient and the long-term implications for prevention and treatment: a case report

Although respiratory viral infections have been associated with acute rejection and bronchiolitis obliterans syndrome, the long-term impact of the novel pandemic influenza A (2009 H1N1) virus on lung transplant patients has not been defined. We describe the diagnostic challenges and long-term consequences of 2009 H1N1 infection in a lung transplant patient, discuss the potential implications for prevention and treatment, and conclude that even timely antiviral therapy may be insufficient to prevent long-term morbidity.

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.

Influenza, including the novel H1N1, in organ transplant patients

PURPOSE OF REVIEW

This article will review the epidemiology, diagnosis, prevention and management of influenza in solid organ transplant recipients.

RECENT FINDINGS

A number of recent studies have documented that influenza vaccination is both well tolerated and generally effective in producing an immunologic response in most solid organ transplant (SOT) recipients. Antiviral use is associated with improved clinical outcomes, but prolonged shedding may require a longer course of therapy than what is currently approved by the FDA. Antiviral resistance emerges rarely in transplant patients and should be considered in all patients with an inadequate clinical and/or virologic response.

SUMMARY

Influenza is associated with significant morbidity and mortality, particularly in lung transplant recipients. Molecular diagnostics are preferred over other diagnostic modalities, if available. Influenza vaccination is well tolerated and provides protective benefit in most SOT recipients; in those with contraindications to vaccination or in whom responses are predicted to be poor, antivirals may be considered. Antiviral therapy is associated with improved outcomes in transplant patients and treatment should be continued until clinically and virologic response have been documented. Resistance, particularly with patients infected with the pandemic influenza A/H1N1, should be considered and treated with an antiviral with predicted activity.

Upper and lower respiratory tract viral infections and acute graft rejection in lung transplant recipients

BACKGROUND

Lung transplant recipients are frequently exposed to respiratory viruses and are particularly at risk for severe complications. The aim of this study was to assess the association among the presence of a respiratory virus detected by molecular assays in bronchoalveolar lavage (BAL) fluid, respiratory symptoms, and acute rejection in adult lung transplant recipients.

METHODS

Upper (nasopharyngeal swab) and lower (BAL) respiratory tract specimens from 77 lung transplant recipients enrolled in a cohort study and undergoing bronchoscopy with BAL and transbronchial biopsies were screened using 17 different polymerase chain reaction-based assays.

RESULTS

BAL fluid and biopsy specimens from 343 bronchoscopic procedures performed in 77 patients were analyzed. We also compared paired nasopharyngeal and BAL fluid specimens collected in a subgroup of 283 cases. The overall viral positivity rate was 29.3% in the upper respiratory tract specimens and 17.2% in the BAL samples (P < .001). We observed a significant association between the presence of respiratory symptoms and positive viral detection in the lower respiratory tract (P = .012). Conversely, acute rejection was not associated with the presence of viral infection (odds ratio, 0.41; 95% confidence interval, 0.20-0.88). The recovery of lung function was significantly slower when acute rejection and viral infection were both present.

CONCLUSIONS

A temporal relationship exists between acute respiratory symptoms and positive viral nucleic acid detection in BAL fluid from lung transplant recipients. We provide evidence suggesting that respiratory viruses are not associated with acute graft rejection during the acute phase of infection.

RNA interference therapy in lung transplant patients infected with respiratory syncytial virus

RATIONALE

Lower respiratory tract infections due to respiratory syncytial virus (RSV) are associated with development of bronchiolitis obliterans syndrome in lung transplant (LTX) recipients. ALN-RSV01 is a small interfering RNA targeting RSV replication.

OBJECTIVES

To determine the safety and explore the efficacy of ALN-RSV01 in RSV infection.

METHODS

We performed a randomized, double-blind, placebo-controlled trial in LTX recipients with RSV respiratory tract infection. Patients were permitted to receive standard of care for RSV. Aerosolized ALN-RSV01 (0.6 mg/kg) or placebo was administered daily for 3 days. Viral load was determined by quantitative reverse transcriptase-polymerase chain reaction on serial nasal swabs. Patients completed symptom score cards twice daily. Lung function, including the incidence of new-onset or progressive bronchiolitis obliterans syndrome, was recorded at Day 90.

MEASUREMENTS AND MAIN RESULTS

We enrolled 24 patients (ALN-RSV01, n = 16; placebo, n = 8); randomization was stratified by ribavirin use. ALN-RSV01 was well tolerated, with no drug-related serious adverse events or post-inhalation perturbations in lung function. Interpretation of viral measures was confounded by baseline differences between the two groups in viral load and time from symptom onset to first dose. Mean daily symptom scores were lower in subjects receiving ALN-RSV01, and the mean cumulative daily total symptom score was significantly lower with ALN-RSV01 (114.7 ± 63.13 vs. 189.3 ± 99.59, P = 0.035). At Day 90, incidence of new or progressive bronchiolitis obliterans syndrome was significantly reduced in ALN-RSV01 recipients compared with placebo (6.3% vs. 50%, P = 0.027).

CONCLUSIONS

ALN-RSV01 was safe and may have beneficial effects on long-term allograft function in LTX patients infected with RSV. Clinical trial registered with www.clinicaltrials.gov (NCT 00658086).

Long-term impact of respiratory viral infection after pediatric lung transplantation

To evaluate the epidemiology and to investigate the impact of RVI on chronic allograft rejection after pediatric lung transplantation, a retrospective study of pediatric lung transplant recipients from 2002 to 2007 was conducted. Association between RVI and continuous and categorical risk factors was assessed using Wilcoxon rank-sum tests and Fisher's exact tests, respectively. Association between risk factors and outcomes were assessed using Cox proportional hazards models. Fifty-five subjects were followed for a mean of 674 days (range 14-1790). Twenty-eight (51%) developed 51 RVI at a median of 144 days post-transplant (mean 246; range 1-1276); 41% of infections were diagnosed within 90 days. Twenty-five subjects developed 39 LRI, and eight subjects had 11 URI. Organisms recovered included rhinovirus (n = 14), adenovirus (n = 10), parainfluenza (n = 10), influenza (n = 5), and RSV (n = 4). Three subjects expired secondary to their RVI (two adenovirus, one RSV). Younger age and prior CMV infection were risks for RVI (HR 2.4 95% CI 1.1-5.3 and 17.0; 3.0-96.2, respectively). RVI was not associated with the development of chronic allograft rejection (p = 0.25) or death during the study period. RVI occurs in the majority of pediatric lung transplant recipients, but was not associated with mortality or chronic allograft rejection.

Incidence and morbidity of human metapneumovirus and other community-acquired respiratory viruses in lung transplant recipients

A. Weinberg, D.M. Lyu, S. Li, J. Marquesen, M.R. Zamora. Incidence and morbidity of human metapneumovirus and other community‐acquired respiratory viruses in lung transplant recipients
Transpl Infect Dis 2010: 12: 330–335. All rights reserved.

Abstract: To determine the role of human metapneumovirus (HMPV) in respiratory tract infections (RTIs) of lung transplant recipients, 60 patients were prospectively enrolled in this study spanning from September 2005 to November 2007. Community‐acquired respiratory viruses (CARVs) were identified by polymerase chain reaction and tissue culture in respiratory secretions. Of 112 RTIs, 51 were associated with ≥1 CARV, including 7 HMPV, 13 respiratory syncytial virus (RSV), 19 parainfluenza virus 1, 2, or 3 (PIV), 16 influenza A or B (FLU), and 3 human rhinoviruses (HRV). Sixteen CARV‐RTIs had multiple pathogens. While the standard protocol was to admit all paramyxoviral RTIs for inhaled ribavirin, 16% CARV‐RTIs required hospitalization because of the severity of their respiratory compromise, including 25% of HPMV‐single‐agent RTI, 38% of RSV single‐agent RTI, 10% of PIV‐single‐agent RTI, and 19% of multiple‐agent RTIs. None of those with non‐CARV RTIs required hospitalization. The incidence of clinically diagnosed acute graft rejection in the first 2 months after an RTI varied from 0 for single‐agent HRV to 88% for single‐agent RSV (25% for single‐agent HMPV). A new diagnosis of chronic graft rejection in the first year after an RTI was made in approximately 25% of the RTIs and did not significantly vary with the etiologic agent. No deaths occurred during this study. In conclusion, HMPV was associated with 6% of the RTIs in lung transplant recipients and its morbidity was similar to the average moribidity of CARVs.

H1N1 novel influenza A in pregnant and immunocompromised patients

OBJECTIVE

To describe the increased risk of severe disease and the appropriate management of patients at high risk such as pregnant women and immunosuppressed patients who acquire novel influenza A (H1N1).

DESIGN

Review of the literature regarding influenza A in these patient groups, and review of published and unpublished data with regard to novel influenza A (H1N1).

MAIN RESULTS

Pregnant women are at increased risk for severe pneumonitis and respiratory failure from influenza infection, particularly during pandemics, including the current pandemic. Fetal morbidity is significant, usually resulting from maternal fever and severe hypoxemia. Early antiviral therapy using oseltamivir may be beneficial, and intensive care unit support should target adequate oxygenation at all times. Immunosuppressed patients are at increased risk for influenza, as well as at risk for more severe or prolonged infection. Patients after hematopoietic stem cell transplantation, after lung transplantation, and those receiving chemotherapy for leukemia are at highest risk, whereas the risk for human immunodeficiency virus-infected individuals appears relatively low. Treatment with antiviral therapy may be beneficial, even after the usual cut-off of 48 hrs after symptom onset.

CONCLUSIONS

Optimal management of these patients is preventive by influenza vaccination, but the neuraminidase inhibitor antiviral agents provide effective treatment.

Viral infections in lung transplant recipients

Viral infections, including beta-herpes viruses and community respiratory viruses, are frequent pathogens in lung transplant recipients. These pathogens have become increasingly recognized as having a significant role in long-term outcomes of lung transplantation, which has been limited by the frequent development of infections, and chronic allograft dysfunction. Community respiratory viruses, such as influenza and respiratory syncytial virus have been associated with both acute rejection and chronic allograft dysfunction, particularly if early treatment was not administered. beta-herpes viruses, particularly cytomegalovirus (CMV), have long been associated with increased mortality in lung transplant recipients, although the advent of effective antiviral strategies has led to improved morbidity and mortality. Because these pathogens have been associated with altered immune responses against the allograft, a better understanding of immunopathogenesis of viral infections may lead to a broader approach to limit the morbidity from these pathogens.

Low incidence of severe respiratory syncytial virus infections in lung transplant recipients despite the absence of specific therapy

BACKGROUND

Respiratory syncytial virus (RSV) infections in lung transplant recipients (LTRs) have been associated with significant morbidity and mortality. Immunoglobulins, ribavirin, and palivizumab are suggested treatments for both pre-emptive and therapeutic purposes. However, in the absence of randomized, placebo-controlled trials, efficacy is controversial and there is toxicity as well as cost concerns.

METHODS

We retrospectively reviewed cases of lower respiratory tract RSV infections in adult LTRs. Diagnosis was based on clinical history, combined with a positive polymerase chain reaction (PCR) and/or viral cultures of bronchoalveolar lavage (BAL) specimens.

RESULTS

Ten symptomatic patients were identified (7 men and 3 women, age range 28 to 64 years). All were hospitalized for community-acquired respiratory tract infections. Two patients had a concomitant acute Grade A3 graft rejection, and 1 patient had a concomitant bacterial pneumonia. Eight patients did not receive a specific anti-RSV treatment because of clinical stability and/or improvement at the time of RSV diagnosis. Only 2 patients (1 with Grade A3 allograft rejection and 1 requiring mechanical ventilation) received ribavirin and palivizumab. All patients recovered without complications and with no persistent RSV infection. However, bronchiolitis obliterans (BOS) staging worsened in 6 patients during the mean follow-up of 45 months.

CONCLUSIONS

Our data suggest that mild RSV infections in LTRs might evolve favorably in the absence of specific anti-viral therapy. However, this observation needs confirmation in a large clinical trial specifically investigating the development of BOS in untreated vs treated patients.

Azithromycin is associated with increased survival in lung transplant recipients with bronchiolitis obliterans syndrome

BACKGROUND

Previous studies have suggested that azithromycin improves lung function in lung transplant recipients with bronchiolitis obliterans syndrome (BOS). However, these studies did not include a non-treated BOS control cohort or perform survival analysis. This study was undertaken to estimate the effect of azithromycin treatment on survival in lung transplant recipients with BOS.

METHODS

We conducted a retrospective cohort study of consecutive lung transplant recipients who developed BOS between 1999 and 2007. An association between azithromycin treatment and death was assessed using univariate and multivariate time-dependent Cox regression analysis.

RESULTS

Of the 178 recipients who developed BOS in our study, 78 did so after 2003 and were treated with azithromycin. The azithromycin-treated and untreated cohorts had similar baseline characteristics. Univariate analysis demonstrated that azithromycin treatment was associated with a survival advantage and this beneficial treatment effect was more pronounced when treatment was initiated during BOS Stage 1. Multivariate analysis demonstrated azithromycin treatment during BOS Stage 1 (adjusted hazard ratio = 0.23, p = 0.01) and absolute forced expiratory volume in 1 second (FEV(1)) at the time of BOS Stage 1 (adjusted hazard ratio = 0.52, p = 0.003) were both associated with a decreased risk of death.

CONCLUSIONS

In lung transplant recipients with BOS Stage 1, azithromycin treatment initiated before BOS Stage 2 was independently associated with a significant reduction in the risk of death. This finding supports the need for a randomized, controlled trial to confirm the impact of azithromycin on survival in lung transplant recipients.

Dynamics of human regulatory T cells in lung lavages of lung transplant recipients

BACKGROUND

Despite advances in the field of lung transplantation, the median survival after lung transplant remains below 5 years. Early rejection is a risk factor for the development of chronic rejection. In animal models of transplant tolerance, regulatory T cells (Tregs) can prevent the establishment of rejection.

METHODS

This study was designed to explore the dynamics of Tregs focally and systemically in lung transplant recipients. Sequential surveillance bronchoscopy results were available in 51 patients with at least four sequential samples recovered from each patient at defined times posttransplant. In 36 individuals, a complete year of follow-up data for BAL was analyzed. In 33 of these individuals had a complete year of follow-up data for peripheral blood monocyte cell specimens were also analyzed. Lung lavage cells were recovered from each bronchoscopy and corresponding blood draw and subjected to polychromatic flow cytometry. The percentage of CD4 lymphocytes, which expressed the intracellular transcription factor FoxP3 was recorded at each point. At each time point, lung biopsy specimens were scored for rejection.

RESULTS

Lung Treg frequency was significantly more variable than blood Treg frequency. Treg frequency in the lung was increased in the aftermath of acute rejection. In contrast, lung Treg frequency declined sequentially in patients demonstrating continued quiescence. Mean BAL Treg level integrated over the first transplant year correlated inversely with the degree of acute cellular rejection. In contrast, blood Treg levels demonstrated no correlation with lung pathology.

CONCLUSIONS

Lung Tregs increase in the setting of acute cellular rejection, whereas declining levels of BAL Tregs correlates with immunologic quiescence.

Influenza in immunosuppressed populations: a review of infection frequency, morbidity, mortality, and vaccine responses

Patients that are immunosuppressed might be at risk of serious influenza-associated complications. As a result, multiple guidelines recommend influenza vaccination for patients infected with HIV, who have received solid-organ transplants, who have received haemopoietic stem-cell transplants, and patients on haemodialysis. However, immunosuppression might also limit vaccine responses. To better inform policy, we reviewed the published work relevant to incidence, outcomes, and prevention of influenza infection in these patients, and in patients being treated chemotherapy and with systemic corticosteroids. Available data suggest that most immunosuppressed populations are indeed at higher risk of influenza-associated complications, have a general trend toward impaired humoral vaccine responses (although these data are mixed), and can be safely vaccinated--although longitudinal data are largely lacking. Randomised clinical trial data were limited to one study of HIV-infected patients with high vaccine efficacy. Better trial data would inform vaccination recommendations on the basis of efficacy and cost in these at-risk populations.

Aspergillus colonization of the lung allograft is a risk factor for bronchiolitis obliterans syndrome

Multiple infections have been linked with the development of bronchiolitis obliterans syndrome (BOS) post-lung transplantation. Lung allograft airway colonization by Aspergillus species is common among lung transplant recipients. We hypothesized that Aspergillus colonization may promote the development of BOS and may decrease survival post-lung transplantation. We reviewed all lung transplant recipients transplanted in our center between January 2000 and June 2006. Bronchoscopy was performed according to a surveillance protocol and when clinically indicated. Aspergillus colonization was defined as a positive culture from bronchoalveolar lavage or two sputum cultures positive for the same Aspergillus species, in the absence of invasive pulmonary Aspergillosis. We found that Aspergillus colonization was strongly associated with BOS and BOS related mortality in Cox regression analyses. Aspergillus colonization typically preceded the development of BOS by a median of 261 days (95% CI 87-520). Furthermore, in a multivariate Cox regression model, Aspergillus colonization was a distinct risk factor for BOS, independent of acute rejection. These data suggest a potential causative role for Aspergillus colonization in the development of BOS post-lung transplantation and raise the possibility that strategies aimed to prevent Aspergillus colonization may help delay or reduce the incidence of BOS.

Community-acquired respiratory viral infections in lung transplant recipients: a single season cohort study

BACKGROUND

The impact of community-acquired respiratory virus (CARV) infections on bronchiolitis obliterans syndrome (BOS) and outcome after lung transplantation (LTx) and diagnostic techniques were prospectively evaluated.

METHODS

A single-center prospective cohort study was performed in LTx-outpatients between October 31, 2005 and April 30, 2006. Symptoms of respiratory tract infections were recorded and nasopharyngeal and oropharyngeal swabs were obtained. Lower respiratory sampling was performed when indicated. Immunofluorescence testing, cultures, and polymerase chain reaction for 12 different CARV were applied. Patients were followed up until December 31, 2007. New onset and BOS-stage was recorded 1 year after presentation.

RESULTS

Three hundred eighty-eight LTx-recipients were screened. Fifty-one percent reported of symptoms of respiratory tract infection. Seven hundred seventy upper and 180 lower respiratory samples were obtained. Thirty-four CARV were detected in 30 patients (7.7%): 12 parainfluenza, 7 respiratory syncytial virus, 6 metapneumovirus, 5 coronavirus, 3 rhinovirus, and 1 influenza virus. At 1 year, 43 new cases of BOS developed. One-year incidence of BOS was 25.0% in CARV-positive versus 9.0% in CARV-negative patients (log-rank P=0.01). Symptomatic CARV-infection proved to be a significant covariate for 1-year BOS-free survival in multivariate analysis (P=0.002, adjusted hazard ratio 4.13). CARV-infection did not influence BOS progression in 88 patients with prior BOS (P 0.45). After paramyxovirus infection, 8 of 24 patients developed new-onset BOS, whereas no case was recorded after rhinovirus and coronavirus infection.

DISCUSSION

Surveillance detected CARV in LTx outpatients infrequently. Symptomatic CARV-infection increases the risk for new onset of BOS, but not progression. Risk to develop BOS was especially increased after paramyxovirus infection.

[Lung transplantation. Indications, long-term results and special impact of follow-up care]

Die Lungentransplantation ist bei weit fortgeschrittenen Lungenerkrankungen nach Ausschöpfung aller Therapiemöglichkeiten eine Therapieoption, welche die Lebensqualität und – bei bestimmten Indikationen (zystische Fibrose, Lungenfibrose, pulmonal arterielle Hypertonie) – Lebenserwartung verbessert. Die Anzahl verfügbarer Spenderorgane ist so gering, dass jeder 6. Patient auf der Warteliste verstirbt. Bei der Auswahl geeigneter Kandidaten sind neben der ursächlichen Lungen- oder Herz-Lungenerkrankung, das Alter, vorhandene Mobilität, Ernährungs- und Muskelstatus und extrapulmonale Begleiterkrankungen entscheidende Kriterien. Postoperative Komplikationen können durch die Operation bedingt, durch eine Transplantatabstoßung (akut oder chronisch), Atemwegskomplikationen, Infektionen und extrapulmonale Folgeerkrankungen auftreten. Die Nachsorge erfolgt immer in Kooperation mit dem Transplantationszentrum und hat in großen Zentren zu einer spürbaren Verbesserung der Langzeitergebnisse geführt.

Respiratory viral infections within one year after pediatric lung transplant

Abstract: To characterize epidemiology and risk factors for respiratory viral infections (RVI) in pediatric lung transplant recipients within the first post‐transplant year, a retrospective multicenter study of pediatric lung transplant recipients from 1988 to 2005 was conducted at 14 centers in the United States and Europe. Data were recorded for 1 year post transplant. Associations between RVI and continuous and categorical risk factors were assessed using Wilcoxon's rank‐sum and χ² tests, respectively. Associations between time to RVI and risk factors or survival were assessed by multivariable Cox proportional hazards models. Of 576 subjects, 79 subjects (14%) had 101 RVI in the first year post transplant. Subjects with RVI were younger than those without RVI (median ages 9.7, 13; P<0.01). Viruses detected included adenovirus (n=25), influenza (n=9), respiratory syncytial virus (n=21), parainfluenza virus (n=19), enterovirus (n=4), and rhinovirus (n=22). In a multivariable model for time to first RVI, etiology other than cystic fibrosis (CF), younger age, and no induction therapy were independently associated with risk of RVI. Cytomegalovirus serostatus and acute rejection were not associated with RVI. RVI was independently associated with decreased 12‐month survival (hazard ratio 2.6, 95% confidence interval 1.6–4.4). RVI commonly occurs after pediatric lung transplantation with risk factors including younger age and non‐CF diagnosis. RVI is associated with decreased 1‐year survival.

Orthotopic mouse lung transplantation as experimental methodology to study transplant and tumor biology

Unlike transplantation of other solid organs, vascularized mouse lung transplantation has only recently been developed. In this protocol, we describe a detailed method for performing a vascularized and aerated mouse orthotopic lung transplant, which to date represents the most physiological mouse model of lung transplantation. The procedure is divided into two separate portions consisting of donor harvest followed by implantation using the cuff technique for bronchovascular anastomoses. After a training period spanning several months, the procedure can be successfully mastered and, in experienced hands, requires approximately 90 min to perform. After an initial learning curve, perioperative survival is close to 100%. As the donor hematopoietic cells in the transplanted lung are replaced by those of the host over time, thereby creating a 'chimeric lung,' this model represents a novel research tool for the study of transplantation biology as well as other disease processes, such as malignancies.

Follicular bronchiolitis: a rare cause of bronchiolitis obliterans syndrome after lung transplantation: a case report

This case report is the first confirmed case of follicular bronchiolitis (FB), a rare bronchiolar disorder characterized by peribronchiolar lymphoid follicles, in a series of over 400 lung transplantations performed in our center. It is to our knowledge, the first publication describing FB after lung transplantation (LTx), presenting as chronic allograft dysfunction or bronchiolitis obliterans syndrome (BOS).

Update on lung transplantation

Lung transplantation is a suitable treatment to improve the quality of life and the prognosis of patients with various end-stage pulmonary diseases. There is a shortage of organs and the number of patients on waiting list is exceeding the number of transplants per year approximately two-fold in most countries. Strategies to increase the donor pool are therefore crucial. The long-term prognosis after lung transplantation is not yet as good as for other transplantation procedures and special complications should be taken into account. Aside from infections chronic organ dysfunction is the main cause of death and the most important prognosis limiting factor. Other typical problems are rejection, bronchus complications, and primary transplant dysfunction. However, the results of large centers show promising improvements in recent years.

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.

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.

The impact of induction on survival after lung transplantation: an analysis of the International Society for Heart and Lung Transplantation Registry

BACKGROUND

The use of induction immunosuppression after lung transplantation remains controversial. In this study, we examined the impact of induction on survival after lung transplantation.

METHODS

We performed a retrospective cohort study of 3970 adult lung transplant recipients reported to the ISHLT Registry. We divided the cohort into three groups based on the use of induction: none, interleukin-2 receptor antagonists (IL-2 RA), and polyclonal antithymocyte globulins (ATG). We estimated graft survival using the Kaplan-Meier method and constructed a multivariable Cox proportional hazards model to examine the impact of induction on graft survival in the context of other variables.

RESULTS

During the study period, 2249 patients received no induction, 1124 received IL-2 RA, and 597 received ATG. Four years after transplantation, recipients treated with IL-2 RA had better graft survival (64%) than those treated with ATG (60%) and those who did not receive induction (57%; log rank p = 0.0067). This survival advantage persisted in the multivariable model for single and bilateral recipients treated with IL-2 RA compared to those who did not receive induction (RR = 0.82, p = 0.007). Similarly, bilateral recipients treated with ATG had a survival advantage over bilateral recipients who did not receive induction (RR = 0.78, p = 0.043), but single lung recipients treated with ATG did not have a survival advantage over single lung recipients who did not receive induction (RR = 1.06, p = 0.58).

CONCLUSIONS

Induction with lL-2 RA for single and bilateral lung recipients and induction with ATG for bilateral recipients are associated with a survival benefit, independent of other variables that might impact survival.

[Infection in lung transplantation]

Actualmente, el trasplante de pulmón se considera un tratamiento válido para un buen número de pacientes con insuficiencia respiratoria grave. De todas formas, las complicaciones son muy frecuentes y pueden llevar a fracaso del injerto a medio y largo plazo y menor supervivencia. De acuerdo con el registro de la International Society for Heart and Lung Transplantation, las tasas de supervivencia al primer, segundo y quinto año fueron, en 2006, del 74, 65 y 47%, respectivamente. El principal obstáculo para el éxito a largo plazo del trasplante de pulmón es el rechazo crónico, caracterizado histológicamente como bronquiolitis obliterante, que acontece en cerca de dos terceras partes de los pacientes. Uno de los factores más importantes para el desarrollo de bronquiolitis obliterante, además del número de rechazos agudos, es la infección y la enfermedad por citomegalovirus (CMV). Recientemente, se ha destacado el papel de la infección por diferentes virus respiratorios como factores de riesgo para el desarrollo de rechazo crónico en receptores de un trasplante de pulmón. Las complicaciones infecciosas son una causa frecuente de morbimortalidad en este tipo de pacientes, y la causa de muerte de cerca de la mitad de ellos. La infección bacteriana es la complicación más frecuente de un receptor de un trasplante de pulmón. Del total, el 35-66% son bacterianas y el 50-85% de los pacientes presentan como mínimo un episodio de infección bacteriana. La segunda causa más frecuente de infección, después de la bacteriana, es la infección por CMV. A pesar de utilizar diferentes estrategias de prevención, la incidencia sigue siendo elevada, y se sitúa alrededor del 7% el primer año postrasplante. Es el único tipo de trasplante de órgano sólido en el cual la etiología más frecuente de la infección fúngica es Aspergillus spp., a diferencia del resto, en que típicamente se deben a Candida spp. La incidencia de aspergilosis invasora se cifra en alrededor del 4%.

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.

Mechanisms of chronic rejection in cardiothoracic transplantation

Despite significant improvements in early post-transplantation survival rates, long-term patient and graft survival have remained poor, due in large part to the vexing problem of chronic allograft rejection. Attempts to combat this problem with intensification of immunosuppression have led to concomitant increases in the rates of fatal malignancies and infections. In cardiac transplantation, chronic rejection is manifested primarily by a disease entity known as cardiac allograft vasculopathy, an occlusive narrowing of the coronary vessels. In lung transplantation, chronic rejection is typified by obliterative bronchiolitis, an airflow limiting narrowing of the bronchioles. From an immunologic standpoint, chronic rejection is believed to be the end result of repeated immune and non-immune insults to the graft. This review examines the pathophysiology of heart and lung chronic, with emphasis on both immune and non-immune causes.

Variability in immunization guidelines in children before and after lung transplantation

Lung transplant candidates and recipients are at high risk of infections from vaccine-preventable diseases. However, well-established guidelines neither exist for pre- and post-transplant vaccination nor do monitoring guidelines for pediatric lung transplant recipients. To ascertain the current vaccination and monitoring practices of pediatric lung transplant centers, a self-administered questionnaire was distributed to the 18 pediatric lung transplant centers within the International Pediatric Lung Transplant Collaborative in April 2006. Sixteen of 18 centers (89%) surveyed responded. Pretransplant, national vaccination guidelines are followed. Eleven centers reported following standardized vaccination guidelines post-transplant. Vaccines were more commonly provided by the primary-care physician pretransplant (69%) rather than post-transplant (38%). Post-transplant, 50% of the centers recommend live vaccines for household contacts but not for the transplant recipient. Pretransplant monitoring of response to prior vaccination was performed inconsistently except for varicella (88%). Only 44% of the transplant centers measure for response to vaccination post-transplant, mostly hepatitis B. Current vaccination practices of pediatric lung transplant centers are heterogeneous. The lung transplant community would be well served by studies designed to evaluate the efficacy of vaccinations in this population.

Treatment of adenovirus pneumonia with cidofovir in pediatric lung transplant recipients

BACKGROUND

Adenovirus pneumonia results in significant morbidity and mortality in lung transplant recipients. Cidofovir allows for directed therapy but can result in nephrotoxicity. We report our experience with cidofovir for the treatment of adenovirus pneumonia in pediatric lung transplant recipients.

METHODS

In a retrospective review, we identified four cases of culture-proven adenovirus pneumonia in children who underwent lung transplantation at Texas Children's Hospital (TCH). All patients received cidofovir 1 mg/kg every other day or three times a week for a total of 4 weeks. Probenecid and intravenous hydration were administered in conjunction with the cidofovir. Intravenous immunoglobulin (IVIg) was given as adjunctive therapy, and immunosuppression was not modified during the treatment course.

RESULTS

The four cases of adenovirus pneumonia comprised 4 of the 54 (7%) lung transplantations performed at TCH from 2002 to 2006, and all were in children <3 years of age. All patients developed pneumonia within 2 months after transplantation. With cidofovir treatment, three of the four children survived. Among the survivors, two developed early bronchiolitis obliterans within 1 year after transplant, and one has continued to have good graft function at 2 years after transplant. All patients maintained normal renal function throughout the treatment course.

CONCLUSIONS

Pediatric lung transplant recipients <3 years of age are at increased risk of adenovirus pneumonia early after transplantation. Cidofovir, when used in the modified dosing regimen and in combination with IVIg and renal protection measures, is a safe and potentially effective treatment option for adenovirus pneumonia in lung transplant recipients.

The influence of maternal respiratory infections during pregnancy on infant lung function

INTRODUCTION

We studied whether maternal respiratory infections during pregnancy adversely influence lung growth and development of the offspring, resulting in poor early life lung function.

METHODS

Infants were participants of the Wheezing Illnesses Study Leidsche Rijn (WHISTLER). Lung function measurements (single occlusion technique) were performed during natural sleep. Questionnaire data were used to obtain information on maternal respiratory infections during pregnancy. Multivariate analysis was conducted to assess the relationship between maternal respiratory infections during pregnancy and resistance and compliance of the respiratory system, adjusting for potential confounding variables.

RESULTS

Lower values of compliance (Crs) were found in infants of mothers with respiratory infections during pregnancy; Crs fell by 5.5% (P = 0.031). The difference in Crs between infants of mothers with and without respiratory infections during pregnancy remained unchanged and statistically significant after adjusting for potential confounding variables. The more respiratory infections the mother experienced during pregnancy, the lower the value of Crs was in her offspring (P for trend = 0.016). Using Crs corrected for body weight the relationship with maternal infections was non-significant, however still showing a trend.

CONCLUSIONS

The results of this study may indicate that mothers who experience respiratory infections during pregnancy have newborns with lower compliance of the respiratory system.

Pulmonary infections in transplantation pathology

CONTEXT

Pulmonary infections are common and often life-threatening in solid organ and stem cell transplant recipients. Understanding their pathology is critical to making improvements in care and survival as well as in surgical techniques, immunosuppression management, prophylaxis, and treatment. Pulmonary infections are particularly common and serious in the susceptible population of lung transplant recipients.

OBJECTIVE

To summarize recent updates in the field for opportunistic infections and some common pathogens, and to consider the role of the diagnostic pulmonary histopathologist as well as advances in molecular diagnosis.

DATA SOURCES

This work is based on a selected review of the relevant medical and scientific literature, with emphasis on lung transplantation experience gained during 2 decades of practice.

CONCLUSIONS

Pulmonary infections in transplant recipients present a diagnostic challenge and are a continuing source of mortality and morbidity despite improvement in prophylaxis and treatment. Accurate diagnosis requires multidisciplinary input from clinicians, radiologists, and pathology disciplines as well as complementary molecular methods.

Maintenance of airway epithelium in acutely rejected orthotopic vascularized mouse lung transplants

Lung transplantation remains the only therapeutic option for many patients suffering from end-stage pulmonary disease. Long-term success after lung transplantation is severely limited by the development of bronchiolitis obliterans. The murine heterotopic tracheal transplantation model has been widely used for studies investigating pathogenesis of obliterative airway disease and immunosuppressive strategies to prevent its development. Despite its utility, this model employs proximal airway that lacks airflow and is not vascularized. We have developed a novel model of orthotopic vascularized lung transplantation in the mouse, which leads to severe vascular rejection in allogeneic strain combinations. Here we characterize differences in the fate of airway epithelial cells in nonimmunosuppressed heterotopic tracheal and vascularized lung allograft models over 28 days. Up-regulation of growth factors that are thought to be critical for the development of airway fibrosis and interstitial collagen deposition were similar in both models. However, while loss of airway epithelial cells occurred in the tracheal model, airway epithelium remained intact and fully differentiated in lung allografts, despite profound vascular rejection. Moreover, we demonstrate expression of the anti-apoptotic protein Bcl-2 in airway epithelial cells of acutely rejected lung allografts. These findings suggest that in addition to alloimmune responses, other stimuli may be required for the destruction of airway epithelial cells. Thus, the model of vascularized mouse lung transplantation may provide a new and more physiologic experimental tool to study the interaction between immune and nonimmune mechanisms affecting airway pathology in lung allografts.

Challenges in pulmonary fibrosis. 2: Bronchiolocentric fibrosis

Bronchiolocentric fibrosis is essentially represented by the pathological pattern of constrictive fibrotic bronchiolitis obliterans. The corresponding clinical condition (obliterative bronchiolitis) is characterised by dyspnoea, airflow obstruction at lung function testing and air trapping with characteristic mosaic features on expiratory high resolution CT scans. Bronchiolitis obliterans may result from many causes including acute diffuse bronchiolar damage after inhalation of toxic gases or fumes, alloimmune chronic processes after lung or haematopoietic stem cell transplantation, or connective tissue disease (especially rheumatoid arthritis). Airway-centred interstitial fibrosis and bronchiolar metaplasia are other features of bronchiolocentric fibrosis.

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.

A mouse model of orthotopic vascularized aerated lung transplantation

Outcomes after lung transplantation are markedly inferior to those after other solid organ transplants. A better understanding of cellular and molecular mechanisms contributing to lung graft injury will be critical to improve outcomes. Advances in this field have been hampered by the lack of a mouse model of lung transplantation. Here, we report a mouse model of vascularized aerated single lung transplantation utilizing cuff techniques. We show that syngeneic grafts have normal histological appearance with minimal infiltration of T lymphocytes. Allogeneic grafts show acute cellular rejection with infiltration of T lymphocytes and recipient-type antigen presenting cells. Our data show that we have developed a physiological model of lung transplantation in the mouse, which provides ample opportunity for the study of nonimmune and immune mechanisms that contribute to lung allograft injury.