Community-acquired Respiratory Viruses Are a Risk Factor for Chronic Lung Allograft Dysfunction

Respiratory infections in lung transplant recipients

PURPOSE OF REVIEW

Morbidity and mortality rates after lung transplantation still remain higher than after other forms of solid organ transplantation, primarily due to a higher risk of infections and the development of chronic lung allograft dysfunction. Thus, a tiered approach highlighting the most significant respiratory pathogens including common opportunistic infections along with diagnostic, treatment and prevention strategies, including vaccination and prophylaxis is needed.

RECENT FINDINGS

The need for intense immunosuppressive therapy to prevent rejection, coupled with the transplanted lung's constant exposure to environment and impaired local defence mechanisms leads to frequent infections. Viral and bacterial infections are most frequent while fungal infections mainly involve the tracheobronchial tract but may be fatal in case of disseminated disease. Some infectious agents are known to trigger acute rejection or contribute to chronic allograft dysfunction. Invasive testing in the form of bronchoscopy with bronchoalveolar lavage is standard and increasing experience in point of care testing is gained to allow early preemptive therapy.

SUMMARY

Timely diagnosis, treatment, and ongoing monitoring are essential, but this can be difficult due to the wide variety of potential pathogens.

COVID-19 caused by the Omicron variant in lung transplant recipients: a single center case series

Background

Although coronavirus disease 2019 (COVID-19) is no longer classified as a Public Health Emergency of International Concern by World Health Organization, its global impact persists. Data on its impact in lung transplant recipients (LTRs) from China remain limited. This study aims to share clinical experiences and provide insights into managing LTRs with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection.

Methods

We conducted a study on LTRs with COVID-19 caused by the Omicron variant from November 17, 2022, to May 1, 2023. Clinical information was gathered retrospectively through electronic medical records, questionnaires, or follow-up telephone calls.

Results

A total of 227 LTRs were reviewed for infection with Omicron variant. After excluding 49 cases without confirmed SARS-CoV-2 infection, this left a final cohort of 178 infected LTRs, accounting for an infection rate of 78.4% (178/227). Of the patients, 50% (89/178) required hospitalization, with an average hospital stay of 16 days [interquartile range (IQR): 9.5-25.5 days]. Of the 89 hospitalized patients, 41.6% (37/89) eventually progressed to severe or critical disease, forming the severe/critical group (S/C group), while the remaining 58.4% (52/89) had mild or moderate disease (M/M group). In comparison to the M/M group, the S/C group had higher C-reactive protein (CRP) (59.6 vs. 16.8 mg/L, P<0.001), Erythrocyte sedimentation rate (45.5 vs. 22.5 mm/h, P=0.005) and D-dimer level (1.09 vs. 0.65 mg/L, P=0.01), but lower CD4+ T lymphocytes count (217 vs. 427 cells/µL, P=0.004). The S/C group had significantly higher rates of combined pulmonary bacterial infection (67.6% vs. 38.5%, P=0.006) and pulmonary fungal infection (73.0% vs. 38.5%, P=0.001) during the course of COVID-19, nearly double that of the M/M group. In a multivariate logistic analysis, elevated CRP (>41.8 mg/L), combined pulmonary fungal infection, and interstitial lung disease (ILD) as primary disease emerged as high-risk factors for developing the severe disease phenotype following Omicron variant infection in LTRs, with respective odds ORs values of 4.23 [95% confidence interval (CI): 1.68-11.23], 4.76 (95% CI: 1.59-15.64), and 5.13 (95% CI: 1.19-29.17). Receiver operating characteristic (ROC) curve analysis showed that CD4+ T lymphocyte count may be a strong marker for predicting death. At a cutoff of 404 cells/µL, sensitivity was 0.509, specificity 0.999, and area under the curve (AUC) was 0.806 (95% CI: 0.678-0.934). Ultimately, 13 recipients succumbed to COVID-19 related respiratory failure or secondary multiple organ dysfunction, resulting in an overall mortality rate of 7.3% (13/178).

Conclusions

LTRs are at high risk of secondary lung infections after Omicron. Key risk factors for severe disease include CRP >41.8 mg/L, ILD as primary disease, and pulmonary fungal infection. CD4+ T lymphocyte count may predict mortality risk in LTRs with COVID-19.

Predicting Time to First Rejection Episode in Lung Transplant Patients Using a Comprehensive Multi-Indicator Model

Background

Rejection hinders long-term survival in lung transplantation, and no widely accepted biomarkers exist to predict rejection risk. This study aimed to develop and validate a prognostic model using laboratory data to predict the time to first rejection episode in lung transplant recipients.

Methods

Data from 160 lung transplant recipients were retrospectively collected. Univariate Cox analysis assessed the impact of patient characteristics on time to first rejection episode. Kaplan-Meier survival analysis, LASSO regression, and multivariate Cox analysis were used to select prognostic indicators and develop a riskScore model. Model performance was evaluated using Kaplan-Meier analysis, time-dependent ROC curves, and multivariate Cox regression.

Results

Patient characteristics were not significantly associated with the time to the first rejection episode. Six laboratory indicators-Activated Partial Thromboplastin Time, IL-10, estimated intrapulmonary shunt, 50% Hemolytic Complement, IgA, and Complement Component 3-were identified as significant predictors and integrated into the riskScore. The riskScore demonstrated good predictive performance. It outperformed individual indicators, was an independent risk factor for rejection, and was validated in the validation dataset.

Conclusion

The riskScore model effectively predicts time to first rejection episode in lung transplant recipients.

Reduced levels of liver kinase B1 in small extracellular vesicles as a predictor for chronic lung allograft dysfunction in cystic fibrosis lung transplant recipients

Small extracellular vesicles (sEVs) isolated from plasma of lung transplant recipients (LTRs) with chronic lung allograft dysfunction (CLAD) contain increased levels of lung associated self-antigens, Kα1 tubulin and collagen V, and decreased expression of the tumor suppressor liver kinase B1 (LKB1). In this study, sEVs were isolated from plasma collected from LTRs with or without cystic fibrosis (CF) from multiple centers at the onset of CLAD and 6 and 12 months before clinical diagnosis of CLAD (n = 32) as well as from time-matched stable controls (n = 25). sEVs were analyzed for Kα1 tubulin, collagen V, and LKB1 by western blot. Exoview R200, a functionalized microarray chip was employed to characterize the LKB1 in sEVs. EVs from non-CF LTRs had higher levels of lung self-antigens (p < 0.05) and lower levels of LKB1 (p = 0.024) 12 months before CLAD diagnosis than those from time-matched stable LTRs; however, in CF LTRs, only LKB1 levels were lower (p = 0.0005) 6 months before diagnosis. Further characterization of sEVs 6 months before CLAD in CF LTRs also demonstrated significantly lower numbers of LKB1 and LKB1/CD9 + sEV particles. Reduced LKB1 in circulating sEVs offers a potential biomarker for the risk of CLAD in LTRs with CF.

Description, clinical impact and early outcome of S. maltophilia respiratory tract infections after lung transplantation, A retrospective observational study

BACKGROUND AND RESEARCH QUESTION

S. maltophilia infections are associated with significant morbidity and mortality. Little is known regarding its presentation, management, and outcome in lung transplant recipients.

STUDY DESIGN AND METHODS

This retrospective case control study reviewed S. maltophilia respiratory tract infection in lung transplant recipients (01/01/2011-31/01/2020) and described the clinical, microbiological and outcome characteristics matched with lung transplant recipients without respiratory tract infection.

RESULTS AND INTERPRETATION

We identified 63 S. maltophilia infections in lung transplant recipients. Among them none were colonized before transplantation. Infections occurred a median of 177 (IQR: 45- 681) days post transplantation. Fifty-four (85.7 %) patients received trimethoprim-sulfamethoxazole (400/80 mg three times a week) to prevent Pneumocystis jirovecii pneumonia (PJP). S. maltophilia strains were susceptible to trimethoprim-sulfamethoxazole, levofloxacin, minocycline and ceftazidime in respectively 85.7 %, 82.5 %, 96.8 % and 34.9 % of cases. Median duration of treatment was 9 days (IQR 7-11.5). Clinical and microbiological recurrence were observed in respectively 25.3 % and 39.7 % of cases. Combination therapy was not associated with a decrease in the risk of recurrence and did not prevent the emergence of resistance. S. maltophilia respiratory tract infection was associated with a decline in FEV-1 at one year.

CONCLUSION

S. maltophilia is an important cause of lower respiratory tract infection in lung transplant recipients. Trimethoprim-sulfamethoxazole use as prophylaxis for PJP doesn't prevent S. maltophilia infection among lung transplant recipients. Levofloxacin and trimethoprim-sulfamethoxazole appear to be the two molecules of choice for the treatment of these infections and new antibiotic strategies (cefiderocol, aztreonam/avibactam) are currently being evaluated for multi-resistant S. maltophilia infections.

Association between Respiratory Virus Infection and Development of De Novo Donor-Specific Antibody in Lung Transplant Recipients

Chronic lung allograft dysfunction (CLAD) is the most common cause of long-term lung allograft failure. Several factors, including respiratory virus infection (RVI), have been associated with CLAD development, but the underlying mechanisms of these associations are not well understood. We hypothesize that RVI in lung transplant recipients elicits the development of donor-specific antibodies (DSAs), thus providing a mechanistic link between RVI and CLAD development. To test this hypothesis, we retrospectively evaluated for the presence of HLA antibodies in a cohort of lung transplant recipients with symptomatic RVI within the first four months post-transplant using sera at two time points (at/directly after the transplant and following RVI) and time-matched controls without RVI (post-transplant). We found a trend toward the development of de novo DSAs in those with symptomatic RVI versus controls [6/21 (29%) vs. 1/21 (5%), respectively, p = 0.09]. No cases or controls had DSA at baseline. We also found increased rates of CLAD and death among those who developed class II DSA versus those who did not (CLAD: 5/7 (71.4%) vs. 19/34 (54.3%), death: 5/7 (71.4%) vs. 17/35 (48.6%)). Prospective studies evaluating the temporal development of DSA after RVI in lung transplant patients and the subsequent outcomes are warranted.

Immunopathology of lung transplantation: from infection to rejection and vice versa

Lung transplantation offers a lifesaving option for patients with end-stage lung disease, but it is marred by a high risk of post-transplant infections, particularly involving multidrug-resistant bacteria, Cytomegalovirus, and fungal pathogens. This elevated infection rate, the highest among solid organ transplants, poses a significant challenge for clinicians, particularly within the first year post-transplantation, where infections are the leading cause of mortality. The direct exposure of lung allografts to the external environment exacerbates this vulnerability leading to constant immune stimulation and consequently to an elevated risk of triggering alloimmune responses to the lung allograft. The necessity of prolonged immunosuppression to prevent allograft rejection further complicates patient management by increasing susceptibility to infections and neoplasms, and complicating the differentiation between rejection and infection, which require diametrically opposed management strategies. This review explores the intricate balance between preventing allograft rejection and managing the heightened infection risk in lung transplant recipients.

COVID-19 infection is mild and has minimal impact on lung function in well vaccinated and widely treated lung transplant recipients

BACKGROUND

COVID-19 has become a common infection affecting lung transplant recipients (LTR), who are at high risk for poor outcomes. Outcomes early in the pandemic were poor, but since the rollout of vaccination and novel COVID-19 treatments, outcomes of LTR have not been well described. Our aim was to evaluate the effect of COVID-19 on the clinical course and lung function trajectory in an Australian cohort of LTR.

METHODS

Data were retrospectively collected from LTR with confirmed COVID-19 managed at Alfred Health, between August 2020 and December 2022. Baseline demographics, COVID-19 disease details (including severity) and spirometry pre- and postinfection have been analyzed.

RESULTS

A total of 279 LTR were included. The cohort was comorbid, but well vaccinated, with 275/279 (98.6%) having ≥2 COVID-19 vaccines at symptom onset. Severe disease occurred in only 17 cases (6%) and overall mortality was very low (4%). Prompt treatment with antivirals, particularly remdesevir (OR 0.18, 95% CI 0.04-0.81, p = 0.02) and vaccination (OR 0.24, CI 0.08-0.81, p = 0.01), was protective. There was not a clinically significant drop in lung function post-COVID-19 with the median absolute decline in forced expiratory volume (FEV1) being 40 ml (IQR 5-120 ml, p < 0.001), with a decline of >10% occurring in only 42 patients (17%). After multivariate adjustment, only rejection before COVID-19 was significantly associated with FEV1 decline afterward (OR 3.74, 1.12-11.86, p = 0.03).

CONCLUSIONS

In our highly COVID-19 vaccinated, promptly treated LTR, the majority of COVID-19 infections were mild and did not result in a clinically significant decline in lung function.

Opportunistic Infections Post-Lung Transplantation: Viral, Fungal, and Mycobacterial

Opportunistic infections are a leading cause of lung transplant recipient morbidity and mortality. Risk factors for infection include continuous exposure of the lung allograft to the external environment, high levels of immunosuppression, impaired mucociliary clearance and decreased cough reflex, and impact of the native lung microbiome in single lung transplant recipients. Infection risk is mitigated through careful pretransplant screening of recipients and donors, implementation of antimicrobial prophylaxis strategies, and routine surveillance posttransplant. This review describes common viral, fungal, and mycobacterial infectious after lung transplant and provides recommendations on prevention and treatment.

Center variability in the prognostic value of a cumulative acute cellular rejection "A-score" for long-term lung transplant outcomes

The acute rejection score (A-score) in lung transplant recipients, calculated as the average of acute cellular rejection A-grades across transbronchial biopsies, summarizes the cumulative burden of rejection over time. We assessed the association between A-score and transplant outcomes in 2 geographically distinct cohorts. The primary cohort included 772 double lung transplant recipients. The analysis was repeated in 300 patients from an independent comparison cohort. Time-dependent multivariable Cox models were constructed to evaluate the association between A-score and chronic lung allograft dysfunction or graft failure. Landmark analyses were performed with A-score calculated at 6 and 12 months posttransplant. In the primary cohort, no association was found between A-score and graft outcome. However, in the comparison cohort, time-dependent A-score was associated with chronic lung allograft dysfunction both as a time-dependent variable (hazard ratio, 1.51; P < .01) and when calculated at 6 months posttransplant (hazard ratio, 1.355; P = .031). The A-score can be a useful predictor of lung transplant outcomes in some settings but is not generalizable across all centers; its utility as a prognostication tool is therefore limited.

Systemic corticosteroids for outpatient respiratory viral infections in lung transplant recipients

INTRODUCTION

Respiratory viral infections (RVI) in lung transplant recipients (LTR) have variably been associated with rejection and chronic lung allograft dysfunction. Our center has used systemic corticosteroids to treat outpatient RVI in some cases, but evidence is limited. We reviewed all adult LTR diagnosed with outpatient RVI January 2017 to December 2019. The primary outcome was recovery of lung function (forced expiratory volume in 1 s [FEV1]) at next stable visit between 1 and 12 months postinfection, expressed as a ratio over stable preinfection FEV1 (FEV1 recovery ratio).

METHODS

We identified 100 adult LTR with outpatient RVI diagnoses eligible for study, 36% of whom received corticosteroids. We modelled the adjusted association between corticosteroid use and FEV1 recovery ratio using linear regression.

RESULTS

Steroid-treated patients had a lower FEV1 presentation ratio (0.92 vs. 1.04, p = .0070) and were more likely to have chronic lung allograft dysfunction at time of infection (25% vs. 5%, p = .0077). Mean FEV1 recovery ratio was 1.02 (SD 0.19) with no association with corticosteroid therapy via multivariable linear regression (p = .5888).

CONCLUSIONS

Steroid treatment was not associated with FEV1 recovery. This suggests corticosteroids may not have a role in the management of RVI in this population.

Evaluation of post-COVID symptoms of the SARS-CoV-2 Delta and Omicron variants in children: a prospective study

The post-COVID-19 syndrome is a new syndrome defined in patients with a history of probable or confirmed SARS-CoV-2 infection, usually within three months of the onset of COVID-19, with symptoms and effects lasting at least 2 months. This study is aimed at comprehensively comparing symptoms of the post-COVID-19 syndrome in children with Delta and Omicron variants. This prospective study included children with COVID-19 followed in hospitalized or outpatient clinics in a tertiary hospital. We used a special questionnaire to ask about the presence of persistent symptoms more than 12 weeks after the initial diagnosis. Patients with positive SARS-CoV-2 PCR were selected randomly and grouped according to the dominant variants in our country at that time as follows: Omicron group (after December 16, 2021); Delta (B.1.617.2) group (August 15, 2021, and December 15, 2021). This study included 200 children, 71 of whom were in the Delta group and 129 of whom were in the Omicron group. Weakness (8.5% vs. 1.6%; p = 0.017), the impact of physical efforts (5.6% vs. 3.9%; p = 0.020), fatigue (22.5% vs. 8.5%; p = 0.009), anxiety disorder (12.7% vs. 0.8%; p = 0.001), and gastrointestinal changes (12.7% vs. 4.7%, p = 0.050) were statistically significantly higher in patients with the Delta variant compared to patients with the Omicron variant. There were no differences between the groups regarding anorexia, anosmia/ageusia, arthralgia, influenza-like symptoms, sleeping disorders, decreased physical activity daily, headache, need for analgesia, concentration and memory disorder, and weight loss (p > 0.05).  Conclusion: This study showed that weakness, the impact of physical efforts, fatigue, anxiety disorder, and gastrointestinal changes were more frequent in the Delta group compared to the Omicron group. The incidence of post-COVID-19 syndrome is high in children as well as adults and affects several systems; therefore, it should be kept in mind that children should be followed for post-COVID-19 syndrome. What is Known: • Despite the milder severity of acute COVID-19 in children, post-COVID-19 symptoms may occur. The post-COVID-19 condition is complex and novel, especially in the pediatric population. What is New: • Post-COVID-19 symptoms in children differ depending on the viral variant. Post-COVID-19 syndrome has a great impact on the social life of children which may have serious and long-term effects.

Incidence and severity of SARS-CoV-2 infection in lung transplant recipients in the Omicron era

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection may cause serious illness in lung transplant recipients. We aimed to investigate incidence and severity of SARS-CoV-2 infection in lung transplant recipients in the Omicron era. We conducted a retrospective study investigating COVID-19 incidence and outcomes among lung transplant recipients between December 27, 2021, and October 31, 2022, in Denmark. We performed COX regression analysis of potential risk factors with hospitalization as an endpoint. Among 236 included patients, 108 had a first positive SARS-CoV-2 polymerase chain reaction during a total of 133 person-years of follow-up, resulting in an incidence rate of 813 per 1000 person-years (95% confidence intervals (CI) 670-977). The cumulative incidence of hospitalization was 24.1% (95% CI 26-32.1) and admission to the intensive care unit was 3.7% (95% CI 0.1-6.3). The 30-day mortality of recipients with a SARS-CoV-2 infection was 0.9% (95% CI 0-2.7). We found that the incidence rate of patients with SARS-CoV-2 infection was markedly higher, whereas the mortality rate was lower in the omicron era compared to earlier reports for lung transplant recipients conducted in the delta era. On the other hand, a substantial proportion of patients were hospitalized, suggesting a continuous impact on this patient population.

Imaging in Lung Transplantation: Surgical Techniques and Complications

Lung transplant is an established treatment for patients with end-stage lung disease. As a result, there is increased demand for transplants. Despite improvements in pretransplant evaluation, surgical techniques, and postsurgical care, the average posttransplant life expectancy is only around 6.5 years. Early recognition of complications on imaging and treatment can improve survival. Knowledge of surgical techniques and imaging findings of surgical and nonsurgical complications is essential. This review covers surgical techniques and imaging appearance of postsurgical and nonsurgical complications, including allograft dysfunction, infections, neoplasms, and recurrence of primary lung disease.

Impact of SARS-CoV-2-Related Hygiene Measures on Community-Acquired Respiratory Virus Infections in Lung Transplant Recipients in Switzerland

Background and Objectives: Community-acquired respiratory virus (CARV) infections pose a serious risk for lung transplant recipients (LTR) as they are prone to severe complications. When the COVID-19 pandemic hit Switzerland in 2020, the government implemented hygiene measures for the general population. We investigated the impact of these measures on the transmission of CARV in lung transplant recipients in Switzerland. Materials and Methods: In this multicenter, retrospective study of lung transplant recipients, we investigated two time periods: the year before the COVID-19 pandemic (1 March 2019-29 February 2020) and the first year of the pandemic (1 March 2020-28 February 2021). Data were mainly collected from the Swiss Transplant Cohort Study (STCS) database. Descriptive statistics were used to analyze the results. Results: Data from 221 Swiss lung transplant cohort patients were evaluated. In the year before the COVID-19 pandemic, 157 infections were diagnosed compared to 71 infections in the first year of the pandemic (decline of 54%, p < 0.001). Influenza virus infections alone showed a remarkable decrease from 17 infections before COVID-19 to 2 infections after the beginning of the pandemic. No significant difference was found in testing behavior; 803 vs. 925 tests were obtained by two of the three centers during the respective periods. Conclusions: We observed a significant decline in CARV infections in the Swiss lung transplant cohort during the first year of the COVID-19 pandemic. These results suggest a relevant impact of hygiene measures when implemented in the population due to the COVID-19 pandemic on the incidence of CARV infections.

Invasive fungal infections after respiratory viral infections in lung transplant recipients are associated with lung allograft failure and chronic lung allograft dysfunction within 1 year

BACKGROUND

Respiratory viral infections (RVI) are associated with chronic lung allograft dysfunction (CLAD) and mortality in lung transplant recipients (LTRs). However, the prevalence and impact of secondary invasive fungal infections (IFIs) post RVIs in LTRs have not been investigated.

METHODS

We performed a single center retrospective study including LTRs diagnosed with 5 different respiratory viral pathogens between January 2010 to May 2021 and evaluated their clinical outcomes in 1 year. The risk factors of IFIs were evaluated by logistic regression. The impact of IFIs on CLAD stage progression/death was examined by Cox regression.

RESULTS

A total of 202 RVI episodes (50 influenza, 31 severe acute respiratory syndrome coronavirus-2, 30 metapneumovirus, 44 parainfluenza, and 47 respiratory syncytial virus) in 132 patients was included for analysis. Thirty-one episodes (15%) were associated with secondary IFIs, and 27 occurred in LTRs with lower respiratory tract infection (LRTI; 28% from 96 LRTI episodes). Aspergillosis was the most common IFI (80%). LTRs with IFIs had higher disease severity during RVI episodes. In multivariable analysis, RVI with LTRI was associated with IFI (adjusted odds ratio [95% confidence interval (CI)] of 7.85 (2.48-24.9). Secondary IFIs were associated with CLAD stage progression/death after accounting for LRTI, pre-existing CLAD, intensive care unit admission, secondary bacterial pneumonia and underlying lung diseases pre-transplant with adjusted hazard ratio (95%CI) of 2.45 (1.29-4.64).

CONCLUSIONS

This cohort demonstrated 15% secondary IFI prevalence in LTRs with RVIs. Importantly, secondary IFIs were associated with CLAD stage progression/death, underscoring the importance of screening for fungal infections in this setting.

Opportunistic Infections Post-Lung Transplantation: Viral, Fungal, and Mycobacterial

Opportunistic infections are a leading cause of lung transplant recipient morbidity and mortality. Risk factors for infection include continuous exposure of the lung allograft to the external environment, high levels of immunosuppression, impaired mucociliary clearance and decreased cough reflex, and impact of the native lung microbiome in single lung transplant recipients. Infection risk is mitigated through careful pretransplant screening of recipients and donors, implementation of antimicrobial prophylaxis strategies, and routine surveillance posttransplant. This review describes common viral, fungal, and mycobacterial infectious after lung transplant and provides recommendations on prevention and treatment.

Elevated cell-free DNA in respiratory viral infection and associated lung allograft dysfunction

Respiratory viral infection (RVI) in lung transplant recipients (LTRs) is a risk for chronic lung allograft dysfunction (CLAD). We hypothesize that donor-derived cell-free DNA (%ddcfDNA), at the time of RVI predicts CLAD progression. We followed 39 LTRs with RVI enrolled in the Genomic Research Alliance for Transplantation for 1 year. Plasma %ddcfDNA was measured by shotgun sequencing, with high %ddcfDNA as ≥1% within 7 days of RVI. We examined %ddcfDNA, spirometry, and a composite (progression/failure) of CLAD stage progression, re-transplant, and death from respiratory failure. Fifty-nine RVI episodes, 38 low and 21 high %ddcfDNA were analyzed. High %ddcfDNA subjects had a greater median %FEV₁ decline at RVI (-13.83 vs. -1.83, p = .007), day 90 (-7.97 vs. 0.91, p = .04), and 365 (-20.05 vs. 1.09, p = .047), compared to those with low %ddcfDNA and experienced greater progression/failure within 365 days (52.4% vs. 21.6%, p = .01). Elevated %ddcfDNA at RVI was associated with an increased risk of progression/failure adjusting for symptoms and days post-transplant (HR = 1.11, p = .04). No difference in %FEV₁ decline was seen at any time point when RVIs were grouped by histopathology result at RVI. %ddcfDNA delineates LTRs with RVI who will recover lung function and who will experience sustained decline, a utility not seen with histopathology.

Critical Care of the Lung Transplant Patient

Lung transplantation is a therapeutic option for end-stage lung disease that improves survival and quality of life. Prelung transplant admission to the intensive care unit (ICU) for bridge to transplant with mechanical ventilation and extracorporeal membrane oxygenation (ECMO) is common. Primary graft dysfunction is an important immediate complication of lung transplantation with short- and long-term morbidity and mortality. Later transplant-related causes of respiratory failure necessitating ICU admission include acute cellular rejection, atypical infections, and chronic lung allograft dysfunction. Lung transplantation for COVID-19-related ARDS is increasingly common..

COVID-19-Associated Lung Fibrosis: Two Pathways and Two Phenotypes, Lung Transplantation, and Antifibrotics

COVID-19 can be associated with lung fibrosis. Although lung fibrosis after COVID-19 is a relatively rare finding, the mere fact that globally a very large number of patients have had COVID-19 leads to a significant burden of disease. However, patients with COVID-19-associated lung fibrosis have different clinical and radiological features. The aim of this review is to define the different phenotypes of COVID-19-associated lung fibrosis, based on the medical literature. We found that two phenotypes have emerged. One phenotype is COVID-19-related acute respiratory distress syndrome (CARDS); the other phenotype is post-COVID-19 pulmonary fibrosis (PCPF). Both phenotypes have different risk factors, clinical, and radiological features, and differ in their pathophysiological mechanisms and prognoses. A long-term follow-up of patients with pulmonary complications after COVID-19 is warranted, even in patients with only discrete fibrosis. Further studies are needed to determine the optimal treatment because currently the literature is scarce, and evidence is only based on small case series or case reports.

Respiratory Syncytial Virus, Human Metapneumovirus, and Parainfluenza Virus Infections in Lung Transplant Recipients: A Systematic Review of Outcomes and Treatment Strategies

Background

Respiratory syncytial virus (RSV), parainfluenza virus (PIV), and human metapneumovirus (hMPV) are increasingly associated with chronic lung allograft dysfunction (CLAD) in lung transplant recipients (LTR). This systematic review primarily aimed to assess outcomes of RSV/PIV/hMPV infections in LTR and secondarily to assess evidence regarding the efficacy of ribavirin.

Methods

Relevant databases were queried and study outcomes extracted using a standardized method and summarized.

Results

Nineteen retrospective and 12 prospective studies were included (total 1060 cases). Pooled 30-day mortality was low (0–3%), but CLAD progression 180–360 days postinfection was substantial (pooled incidences 19–24%) and probably associated with severe infection. Ribavirin trended toward effectiveness for CLAD prevention in exploratory meta-analysis (odds ratio [OR] 0.61, [0.27–1.18]), although results were highly variable between studies.

Conclusions

RSV/PIV/hMPV infection was followed by a high CLAD incidence. Treatment options, including ribavirin, are limited. There is an urgent need for high-quality studies to provide better treatment options for these infections.

Bronchiolitis obliterans syndrome after lung or haematopoietic stem cell transplantation: current management and future directions

Bronchiolitis obliterans syndrome (BOS) may develop after either lung or haematopoietic stem cell transplantation (HSCT), with similarities in histopathological features and clinical manifestations. However, there are differences in the contributory factors and clinical trajectories between the two conditions. BOS after HSCT occurs due to systemic graft-versus-host-disease (GVHD), whereas BOS after lung transplantation is limited to the lung allograft. BOS diagnosis after HSCT is more challenging, as the lung function decline may occur due to extrapulmonary GVHD, causing sclerosis or inflammation in the fascia or muscles of the respiratory girdle. Treatment is generally empirical with no established effective therapies. This review provides rare insights and commonalities of both conditions, that are not well elaborated elsewhere in contemporary literature, and highlights the importance of cross disciplinary learning from experts in other transplant modalities. Treatment algorithms for each condition are presented, based on the published literature and consensus clinical opinion. Immunosuppression should be optimised, and other conditions or contributory factors treated where possible. When initial treatment fails, the ultimate therapeutic option is lung transplantation (or re-transplantation in the case of BOS after lung transplantation) in carefully selected candidates. Novel therapies under investigation include aerosolised liposomal cyclosporine, Janus kinase inhibitors, antifibrotic therapies, and (in patients with BOS after lung transplantation) B-cell–directed therapies. Effective novel treatments that have a tangible impact on survival and thereby avoid the need for lung transplantation or re-transplantation are urgently required.

One-year immunologic outcomes of lung transplantation utilizing hepatitis C-viremic donors

Little is known about the effects of hepatitis C viremia on immunologic outcomes in the era of direct-acting antivirals. We conducted a prospective, single-arm trial of lung transplantation from hepatitis C-infected donors into hepatitis C-naïve recipients (n = 21). Recipients were initiated on glecaprevir-pibrentasvir immediately post-transplant and were continued on therapy for a total of 8 weeks. A control group of recipients of hepatitis C-negative lungs were matched 1:1 on baseline variables (n = 21). The primary outcome was the frequency of acute cellular rejection over 1-year post-transplant. Treatment with glecaprevir-pibrentasvir was well tolerated and resulted in viremia clearance after a median of 16 days of therapy (IQR 10-24 days). At one year, there was no difference in incidence of acute cellular rejection (71.4% vs. 85.7%, P = .17) or rejection requiring treatment (33.3% vs. 57.1%, P = .12). Mean cumulative acute rejection scores were similar between groups (.46 [SD ± .53] vs. .52 [SD ± .37], P = .67). Receipt of HCV+ organs was not associated with acute rejection on unadjusted Cox regression analysis (HR .55, 95% CI .28-1.11, P = .09), or when adjusted for risk factors known to be associated with acute rejection (HR .57, 95% CI .27-1.21, P = .14). Utilization of hepatitis C infected lungs with immediate treatment leads to equivalent immunologic outcomes at 1 year.

The effect of COVID-19 on transplant function and development of CLAD in lung transplant patients: a multicenter experience

Background

Concerns have been raised on the impact of coronavirus disease (COVID-19) on lung transplant (LTx) patients. The aim of this study was to evaluate the transplant function pre- and post-COVID-19 in LTx patients.

Methods

Data were retrospectively collected from LTx patients with confirmed COVID-19 from all 3 Dutch transplant centers, between February 2020 and September 2021. Spirometry results were collected pre-COVID-19, 3- and 6-months post infection.

Results

Seventy-four LTx patients were included. Forty-two (57%) patients were admitted, 19 (26%) to the intensive care unit (ICU). The in-hospital mortality was 20%. Twelve out of 19 ICU patients died (63%), a further 3 died on general wards. Patients with available spirometry (78% at 3 months, 65% at 6 months) showed a significant decline in mean forced expiratory volume in 1 second (FEV1) (ΔFEV1 138 ± 39 ml, p = 0.001), and forced vital capacity (FVC) (ΔFVC 233 ±74 ml, p = 0.000) 3 months post infection. Lung function improved slightly from 3 to 6 months after COVID-19 (ΔFEV1 24 ± 38 ml; ΔFVC 100 ± 46 ml), but remained significantly lower than pre-COVID-19 values (ΔFEV1 86 ml ± 36 ml, p = 0.021; ΔFVC 117 ± 35 ml, p = 0.012). FEV1/FVC was > 0.70.

Conclusions

In LTx patients COVID-19 results in high mortality in hospitalized patients. Lung function declined 3 months after infection and gradually improved at 6 months, but remained significantly lower compared to pre-COVID-19 values. The more significant decline in FVC than in FEV1 and FEV1/FVC > 70%, suggested a more restrictive pattern.

Viral infections in lung transplantation

Viral infections account for up to 30% of all infectious complications in lung transplant recipients, remaining a significant cause of morbidity and even mortality. Impact of viral infections is not only due to the direct effects of viral replication, but also to immunologically-mediated lung injury that may lead to acute rejection and chronic lung allograft dysfunction. This has particularly been seen in infections caused by herpesviruses and respiratory viruses. The implementation of universal preventive measures against cytomegalovirus (CMV) and influenza (by means of antiviral prophylaxis and vaccination, respectively) and administration of early antiviral treatment have reduced the burden of these diseases and potentially their role in affecting allograft outcomes. New antivirals against CMV for prophylaxis and for treatment of antiviral-resistant CMV infection are currently being evaluated in transplant recipients, and may continue to improve the management of CMV in lung transplant recipients. However, new therapeutic and preventive strategies are highly needed for other viruses such as respiratory syncytial virus (RSV) or parainfluenza virus (PIV), including new antivirals and vaccines. This is particularly important in the advent of the COVID-19 pandemic, for which several unanswered questions remain, in particular on the best antiviral and immunomodulatory regimen for decreasing mortality specifically in lung transplant recipients. In conclusion, the appropriate management of viral complications after transplantation remain an essential step to continue improving survival and quality of life of lung transplant recipients.

Prevention of viral infections in solid organ transplant recipients in the era of COVID-19: a narrative review

INTRODUCTION

In solid organ transplant (SOT) recipients, viral infections are associated with direct morbidity and mortality and may influence long-term allograft outcomes. Prevention of viral infections by vaccination, antiviral prophylaxis, and behavioral measures is therefore of paramount importance.

AREAS COVERED

We searched Pubmed to select publications to review current preventive strategies against the most important viral infections in SOT recipients, including SARS-CoV-2, influenza, CMV, and other herpesvirus, viral hepatitis, measles, mumps, rubella, and BK virus.

EXPERT OPINION

The clinical significance of the reduced humoral response following mRNA SARS-CoV-2 vaccines in SOT recipients still needs to be better clarified, in particular with regard to the vaccines' efficacy in preventing severe disease. Although a third dose improves immunogenicity and is already integrated into routine practice in several countries, further research is still needed to explore additional interventions. In the upcoming years, further data are expected to better delineate the role of virus-specific cell mediated immune monitoring for the prevention of CMV and potentially other viral diseases, and the role of the letermovir in the prevention of CMV in SOT recipients. Future studies including clinical endpoints will hopefully facilitate the integration of successful new influenza vaccination strategies into clinical practice.

Respiratory Viruses in Solid Organ Transplant Recipients

Solid organ transplantation is often lifesaving, but does carry an increased risk of infection. Respiratory viral infections are one of the most prevalent infections, and are a cause of significant morbidity and mortality, especially among lung transplant recipients. There is also data to suggest an association with acute rejection and chronic lung allograft dysfunction in lung transplant recipients. Respiratory viral infections can appear at any time post-transplant and are usually acquired in the community. All respiratory viral infections share similar clinical manifestations and are all currently diagnosed using nucleic acid testing. Influenza has good treatment options and prevention strategies, although these are hampered by resistance to neuraminidase inhibitors and lower vaccine immunogenicity in the transplant population. Other respiratory viruses, unfortunately, have limited treatments and preventive methods. This review summarizes the epidemiology, clinical manifestations, therapies and preventive measures for clinically significant RNA and DNA respiratory viruses, with the exception of SARS-CoV-2. This area is fast evolving and hopefully the coming decades will bring us new antivirals, immunologic treatments and vaccines.

The lung microbiome in lung transplantation

Culture-independent study of the lower respiratory tract after lung transplantation has enabled an understanding of the microbiome - that is, the collection of bacteria, fungi, and viruses, and their respective gene complement - in this niche. The lung has unique features as a microbial environment, with balanced entry from the upper respiratory tract, clearance, and local replication. There are many pressures impacting the microbiome after transplantation, including donor allograft factors, recipient host factors such as underlying disease and ongoing exposure to the microbe-rich upper respiratory tract, and transplantation-related immunosuppression, antimicrobials, and postsurgical changes. To date, we understand that the lung microbiome after transplant is dysbiotic; that is, it has higher biomass and altered composition compared to a healthy lung. Emerging data suggest that specific microbiome features may be linked to host responses, both immune and non-immune, and clinical outcomes such as chronic lung allograft dysfunction (CLAD), but many questions remain. The goal of this review is to put into context our burgeoning understanding of the lung microbiome in the postlung transplant patient, the interactions between microbiome and host, the role the microbiome may play in post-transplant complications, and critical outstanding research questions.

Post-COVID-19 symptoms 6 months after acute infection among hospitalized and non-hospitalized patients

OBJECTIVES

To assess the prevalence of and factors associated with post-coronavirus disease 2019 (COVID-19) syndrome 6 months after the onset.

METHODS

A bidirectional prospective study. Interviews investigated symptoms potentially associated with COVID-19 6 months after the disease onset of all consecutive adult inpatients and outpatients with COVID-19 attending Udine Hospital (Italy) from March to May 2020. IgG antibodies against Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) were also evaluated 6 months after the onset of symptoms, at the time of the interview.

RESULTS

A total of 599 individuals were included (320 female, 53.4%; mean age 53 years, SD 15.8) and interviewed 187 days (22 SD) after onset. The prevalence of post-COVID-19 syndrome was 40.2% (241/599). The presence of IgG antibodies was significantly associated with the occurrence of post-COVID-19 syndrome (OR 2.56, 95% CI 1.48-4.38, p 0.001) and median SARS-CoV-2 IgG titres were significantly higher in patients with post-COVID-19 syndrome than in patients without symptoms (42.1, IQR 17.1-78.4 vs. 29.1, IQR 12.1-54.2 kAU/L, p 0.004). Female gender (OR 1.55, 95% CI 1.05-2.27), a proportional increase in the number of symptoms at the onset of COVID-19 (OR 1.81, 95% CI 1.59-2.05) and ICU admission OR 3.10, 95% CI 1.18-8.11) were all independent risk factors for post-COVID-19 syndrome. The same predictors also emerged in a subgroup of 231 patients with the serological follow-up available at the time of the interview alongside the proportional increase in anti-SARS-CoV-2 IgG (OR 1.01, 95% CI 1.00-1.02, p 0.04).

DISCUSSION

Prospective follow-up could be offered to specific subgroups of COVID-10 patients, to identify typical symptoms and persistently high anti-SARS-CoV-2 IgG titres as a means of early detection of post-COVID-19 long-term sequelae.

Comparing cytomegalovirus diagnostics by cell culture and quantitative nucleic acid testing in broncho-alveolar lavage fluids

Many clinical laboratories have replaced virus isolation in cell-culture (VIC) for cytomegalovirus (CMV) by quantitative-nucleic-acid testing (QNAT), rendering clinically relevant CMV-replication difficult to distinguish from CMV-shedding or latent infection. We compared direct VIC in 1109 consecutive bronchoalveolar lavage fluids (BALFs) and a well-validated CMV-QNAT (Basel-CMV-UL111a-77bp). In the retrospective Group 1 (N = 694) and Group 2 (N = 303), CMV-QNAT was performed within 48 h from 2-fold and 10-fold concentrated total nucleic acid (TNA) eluates, respectively. In Group 3 (N = 112), 2-fold and 10-fold concentrated TNA eluates were prospectively analyzed in parallel to VIC. CMV was detected by VIC in 79 of 694 (11%) and 26 of 303 (9%) of Groups 1 and 2, but in 114 of 694 (16%) and 57 of 303 (17%) by CMV-QNAT, respectively. Median CMV loads were significantly higher in VIC-positive than in VIC-negative BALF. The likelihood for CMV detection by VIC was 85% for BALF CMV- loads >4 log10 copies/ml. In the prospective Group 3, CMV was detected by VIC in 10 of 112 (9%), and in 14 of 112 (13%) and 20 of 112 (18%) by CMV-QNAT, when using 2-fold and 10-fold concentrated TNA eluates, respectively. Notably, CMV was undetectable by CMV-QNAT in 10 VIC-positive cases of Groups 1 and 2, but in none of Group 3. We conclude that CMV-QNAT can be adopted to BALF diagnostics but requires several careful steps in validation. CMV-QNAT loads >10 000 copies/ml in BALF may indicate significant CMV replication as defined by VIC, if short shipment and processing procedures can be guaranteed. Discordance of detecting CMV in time-matched plasma samples emphasises the role of local pulmonary CMV replication, for which histopathology remains the gold standard of proven CMV pneumonia.

Donor derived cell free DNA% is elevated with pathogens that are risk factors for acute and chronic lung allograft injury

BACKGROUND

Acute and chronic forms of lung allograft injury are associated with specific respiratory pathogens. Donor-derived cell free DNA (ddcfDNA) has been shown to be elevated with acute lung allograft injury and predictive of long-term outcomes. We examined the %ddcfDNA values at times of microbial isolation from bronchoalveolar lavage (BAL).

METHODS

Two hundred and six BAL samples from 51 Lung Transplant Recipients (LTRs) with concurrently available plasma %ddcfDNA were analyzed along with microbiology and histopathology. Microbial species were grouped into bacterial, fungal, and viral and "higher risk" and "lower risk" cohorts based on historical association with downstream allograft dysfunction. Analyses were performed to determine pathogen category association with %ddcfDNA, independent of inter-subject variability.

RESULTS

Presence of microbial isolates in BAL was not associated with elevated %ddcfDNA compared to samples without isolates. However, "higher risk" bacterial and viral microbes showed greater %ddcfDNA values than lower risk species (1.19% vs. 0.65%, p < 0.01), independent of inter-subject variability. Histopathologic abnormalities concurrent with pathogen isolation were associated with higher %ddcfDNA compared to isolation episodes with normal histopathology (medians 1.23% and 0.66%, p = 0.05). Assessments showed no evidence of correlation between histopathology or bronchoscopy indication and presence of higher risk vs. lower risk pathogens.

CONCLUSION

%ddcfDNA is higher among cases of microbial isolation with concurrent abnormal histopathology and with isolation of higher risk pathogens known to increase risk of allograft dysfunction. Future studies should assess if %ddcfDNA can be used to stratify pathogens for risk of CLAD and identify pathogen associated injury prior to histopathology.

Community-Acquired Respiratory Viruses Post-Lung Transplant

Survival in lung transplant recipients (LTRs) lags behind heart, liver, and kidney transplant, in part due to the direct and indirect effects of infection. LTRs have increased susceptibility to infection due to the combination of a graft continually exposed to the outside world, multiple mechanisms for impaired mucus clearance, and immunosuppression. Community-acquired respiratory viral infections (CARVs) are common in LTRs. Picornaviruses have roughly 40% cumulative incidence followed by respiratory syncytial virus and coronaviruses. Although single-center retrospective and prospective series implicate CARV in rejection and mortality, conclusive evidence for and well-defined mechanistic links to long-term outcome are lacking. Treatment of viral infections can be challenging except for influenza. Future studies are needed to develop better treatments and clarify the links between CARV and long-term outcomes.

The potential of biomarkers of fibrosis in chronic lung allograft dysfunction

Chronic lung allograft dysfunction (CLAD) is the major long-term cause of morbidity and mortality after lung transplantation. Both bronchiolitis obliterans syndrome and restrictive lung allograft syndrome, two main types of CLAD, lead to fibrosis in either the small airways or alveoli and pleura. Pathological pathways in CLAD and other types of fibrosis, for example idiopathic pulmonary fibrosis, are assumed to overlap and therefore fibrosis biomarkers could aid in the early detection of CLAD. These biomarkers could help to differentiate between different phenotypes of CLAD and could, in comparison to biomarkers of inflammation, possibly distinguish an infectious event from CLAD when a decline in lung function is present. This review gives an overview of known CLAD specific biomarkers, describes new promising fibrosis biomarkers currently investigated in other types of fibrosis, and discusses the possible use of these fibrosis biomarkers for CLAD.

Burden, epidemiology, and outcomes of microbiologically confirmed respiratory viral infections in solid organ transplant recipients: a nationwide, multi-season prospective cohort study

Solid organ transplant (SOT) recipients are exposed to respiratory viral infection (RVI) during seasonal epidemics; however, the associated burden of disease has not been fully characterized. We describe the epidemiology and outcomes of RVI in a cohort enrolling 3294 consecutive patients undergoing SOT from May 2008 to December 2015 in Switzerland. Patient and allograft outcomes, and RVI diagnosed during routine clinical practice were prospectively collected. Median follow-up was 3.4 years (interquartile range 1.61-5.56). Six hundred ninety-six RVIs were diagnosed in 151/334 (45%) lung and 265/2960 (9%) non-lung transplant recipients. Cumulative incidence was 60% (95% confidence interval [CI] 53%-69%) in lung and 12% (95% CI 11%-14%) in non-lung transplant recipients. RVI led to 17.9 (95% CI 15.7-20.5) hospital admissions per 1000 patient-years. Intensive care unit admission was required in 4% (27/691) of cases. Thirty-day all-cause case fatality rate was 0.9% (6/696). Using proportional hazard models we found that RVI (adjusted hazard ratio [aHR] 2.45; 95% CI 1.62-3.73), lower respiratory tract RVI (aHR 3.45; 95% CI 2.15-5.52), and influenza (aHR 3.57; 95% CI 1.75-7.26) were associated with graft failure or death. In this cohort of SOT recipients, RVI caused important morbidity and may affect long-term outcomes, underlying the need for improved preventive strategies.

COVID-19 in lung transplant recipients: A multicenter study

This study describes the clinical presentation, treatment, and outcomes of SARS-CoV-2 infection in lung transplant recipients (LTRs). This is a multicenter, retrospective study of all adult LTRs with confirmed SARS-CoV-2 infection from March 4 until April 28, 2020 in six Spanish reference hospitals for lung transplantation. Clinical and radiological data, treatment characteristics, and outcomes were reviewed. Forty-four cases were identified in that period. The median time from transplantation was 4.2 (interquartile range: 1.11-7.3) years. Chest radiography showed acute parenchymal abnormalities in 32 (73%) cases. Hydroxychloroquine was prescribed in 41 (93%), lopinavir/ritonavir (LPV/r) in 14 (32%), and tocilizumab in 19 (43%) patients. There was a strong interaction between tacrolimus and LPV/r in all cases. Thirty-seven (84%) patients required some degree of respiratory support and/or oxygen therapy, and 13 (30%) were admitted to intermediate or intensive critical care units. Seventeen (39%) patients had died and 20 (45%) had been discharged at the time of the last follow-up. Deceased patients had a worse respiratory status and chest X-ray on admission and presented with higher D-dimer, interleukin-6, and lactate dehydrogenase levels. In this multicenter LTR cohort, SARS-CoV-2 presented with high mortality. Additionally, the severity of disease on presentation predicted subsequent mortality.

Challenges in the use of highly effective modulator treatment for cystic fibrosis

The last decade has seen development of oral, small molecule therapies that address the basic cystic fibrosis transmembrane conductance regulator (CFTR) protein defect. Highly effective modulator treatment (HEMT) that is efficacious for a large majority of people living with cystic fibrosis (CF) promises to change the landscape of this chronic life-limiting disease. Some people living with CF have a CFTR genotype that renders them eligible for HEMT, but also have comorbidities that excluded them from the original Phase III clinical trials that led to US Food and Drug Administration approval. The purpose of this review is to address the use of HEMT in challenging situations, including initiation for those with advanced CF lung disease, and use after solid organ transplant, during pregnancy, and for individuals with CFTR-related disorders without a definitive diagnosis of CF.

Evaluation of 10 years of parainfluenza virus, human metapneumovirus, and respiratory syncytial virus infections in lung transplant recipients

Respiratory tract infection with pneumoviruses (PVs) and paramyxoviruses (PMVs) are increasingly associated with chronic lung allograft dysfunction (CLAD) in lung transplant recipients (LTRs). Ribavirin may be a treatment option but its effectiveness is unclear, especially with respect to infection severity. We retrospectively analyzed 10 years of PV/PMV infections in LTRs. The main end points were forced expiratory volume in 1 second (FEV₁ ) at 3 and 6 months postinfection, expressed as a percentage of pre-infection FEV₁ and incidence of new or progressed CLAD 6 months postinfection. A total of 139 infections were included: 88 severe infections (63%) (defined as >10% FEV₁ loss at infection) and 51 mild infections (37%) (≤10% FEV₁ loss). Overall postinfection CLAD incidence was 20%. Associations were estimated on postinfection FEV₁ for ribavirin vs no ribavirin (+13.2% [95% CI: 7.79; 18.67]) and severe vs mild infection (-11.1% [95% CI: -14.76; -7.37]). Factors associated with CLAD incidence at 6 months were ribavirin treatment (odds ratio (OR [95% CI]) 0.24 [0.10; 0.59]), severe infection (OR [95% CI] 4.63 [1.66; 12.88]), and mycophenolate mofetil use (OR [95% CI] 0.38 [0.14; 0.97]). These data provide valuable information about the outcomes of lung transplant recipients with these infections and suggests possible associations of ribavirin use and infection severity with long-term outcomes. Well-designed prospective trials are needed to confirm these findings.

Infectious Complications in Lung Transplant Recipients

Lung transplantation is a lifesaving intervention for patients with advanced lung disease. Due to a combination of immunosuppression, continuous exposure of the lungs to the environment, and complications at the anastomotic sites, lung transplant recipients are at high risk for infectious complications. The aim of this review is to summarize recent developments in the field of infectious diseases as it pertains to lung transplant recipients.

General Approach to the Clinical Care of Solid Organ Transplant Recipients with COVID-19 Infection: Management for Transplant Recipients

PURPOSE OF REVIEW

Insufficient knowledge about COVID-19 and the potential risks of COVID-19 are limiting organ transplantation in wait-listed candidates and deferring essential health care in solid organ transplant recipients. In this review, we expand the understanding and present an overview of the optimized management of COVID-19 in solid organ transplant recipients.

RECENT FINDINGS

Transplant recipients are at an increased risk of severe COVID-19. The unique characteristics of transplant recipients can make it more difficult to identify COVID-19. Based on the COVID-19 data to date and our experience, we present testing, management, and prevention methods for COVID-19. Comprehensive diagnostic tests should be performed to determine disease severity, phase of illness, and identify other comorbidities in transplant recipients diagnosed with COVID-19. Outpatients should receive education for preventative measures and optimal health care delivery minimizing potential infectious exposures. Multidisciplinary interventions should be provided to hospitalized transplant recipients for COVID-19 because of the complexity of caring for transplant recipients.

SUMMARY

Transplant recipients should strictly adhere to infection prevention measures. Understanding of the transplant specific pathophysiology and development of effective treatment strategies for COVID-19 should be prioritized.

Epidemiology and persistence of rhinovirus in pediatric lung transplantation

BACKGROUND

Infection with rhinovirus (HRV) occurs following pediatric lung transplantation. Prospective studies documenting frequencies, persistence, and progression of HRV in this at-risk population are lacking.

METHODS

In the Clinical Trials in Organ Transplant in Children prospective observational study, we followed 61 lung transplant recipients for 2 years. We quantified molecular subtypes of HRV in serially collected nasopharyngeal (NP) and bronchoalveolar lavage (BAL) samples and correlated them with clinical characteristics.

RESULTS

We identified 135 community-acquired respiratory infections (CARV) from 397 BAL and 480 NP samples. We detected 93 HRV events in 42 (68.8%) patients, 22 of which (23.4%) were symptomatic. HRV events were contiguous with different genotypes identified in 23 cases, but symptoms were not preferentially associated with any particular species. Nine (9.7%) HRV events persisted over multiple successive samples for a median of 36 days (range 18-408 days). Three persistent HRV were symptomatic. When we serially measured forced expiratory volume in one second (FEV1) in 23 subjects with events, we did not observe significant decreases in lung function over 12 months post-HRV.

CONCLUSION

In conjunction with our previous reports, our prospectively collected data indicate that molecularly heterogeneous HRV infections occur commonly following pediatric lung transplantation, but these infections do not negatively impact clinical outcomes.

Etiologies and Outcomes of Acute Respiratory Failure in Solid Organ Transplant Recipients: Insight Into the EFRAIM Multicenter Cohort

BACKGROUND

Respiratory complications of solid organ transplant (SOT) are a diagnostic and therapeutic challenge when requiring intensive care unit (ICU) admission. We aimed at describing this challenge in a prospective cohort of SOT recipients admitted in the ICU.

METHODS

In this post hoc analysis of an international cohort of immunocompromised patients admitted in the ICU for an acute respiratory failure, we analyzed all SOT recipients and compared their severity, etiologic diagnosis, prognosis, and outcome according to the performance of an invasive diagnostic strategy (encompassing a fiber-optic bronchoscopy and bronchoalveolar lavage), the type of transplanted organ, and the need of invasive ventilation at day 1.

RESULTS

Among 1611 patients included in the primary study, 142 were SOT recipients (kidney, n = 73; 51.4%; lung, n = 33; 23.2%; liver, n = 29; 20.4%; heart, n = 7; 4.9%). Lung transplant recipients were younger than other SOT recipients, and severity did not differ across type of received organ. An invasive diagnostic strategy was more frequently performed in lung transplant recipients with a trend toward a higher rate of bacterial etiology in lung than kidney transplant recipients. Overall ICU survival of SOT recipients was 75.4%. Invasive diagnostic strategy, type of transplanted organ, and need of invasive mechanical ventilation at day 1 did not affect ICU prognosis.

CONCLUSIONS

ICU management of hypoxemic acute respiratory failure in SOT recipients translated into a low ICU mortality rate, whatever the transplanted organ or the acute respiratory failure cause. The post-ICU burden of acute respiratory failure SOT recipients remains to be investigated.

Recommended prophylactic and management strategies for severe acute respiratory syndrome coronavirus 2 infection in transplant recipients

Since December 2019, increasing attention has been paid to the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) epidemic in Wuhan, China. SARS-CoV-2 primarily invades the respiratory tract and lungs, leading to pneumonia and other systemic disorders. The effect of SARS-CoV-2 in transplant recipients has raised significant concerns, especially because there is a large population of transplant recipients in China. Based on the current epidemic situation, this study reviewed publications on this virus and coronavirus disease 2019 (COVID-19), analyzed common features of respiratory viral pneumonias, and presented the currently reported clinical characteristics of COVID-19 in transplant recipients to improve strategies regarding the diagnosis and treatment of COVID-19 in this special population.

Surveillance for acute cellular rejection after lung transplantation

Acute cellular rejection (ACR) is a common complication following lung transplantation (LTx), affecting almost a third of recipients in the first year. Established, comprehensive diagnostic criteria exist but they necessitate allograft biopsies which in turn increases clinical risk and can pose certain logistical and economic problems in service delivery. Undermining these challenges further, are known problems with inter-observer interpretation of biopsies and uncertainty as to the long-term implications of milder or indeed asymptomatic episodes. Increased risk of chronic lung allograft dysfunction (CLAD) has long been considered the most significant consequence of ACR. Consensus is lacking as to whether this applies to mild ACR, with contradictory evidence available. Given these issues, research into alternative, minimal or non-invasive biomarkers represents the main focus of research in ACR. A number of potential markers have been proposed, but none to date have demonstrated adequate sensitivity and specificity to allow translation from bench to bedside.

Absence of evidence that respiratory viral infections influence pediatric lung transplantation outcomes: Results of the CTOTC-03 study

Based on reports in adult lung transplant recipients, we hypothesized that community-acquired respiratory viral infections (CARVs) would be a risk factor for poor outcome after pediatric lung transplant. We followed 61 pediatric lung transplant recipients for 2+ years or until they met a composite primary endpoint including bronchiolitis obliterans syndrome/obliterative bronchiolitis, retransplant, or death. Blood, bronchoalveolar lavage, and nasopharyngeal specimens were obtained with standard of care visits. Nasopharyngeal specimens were obtained from recipients with respiratory viral symptoms. Respiratory specimens were interrogated for respiratory viruses by using multiplex polymerase chain reaction. Donor-specific HLA antibodies, self-antigens, and ELISPOT reactivity were also evaluated. Survival was 84% (1 year) and 68% (3 years). Bronchiolitis obliterans syndrome incidence was 20% (1 year) and 38% (3 years). The primary endpoint was met in 46% of patients. CARV was detected in 156 patient visits (74% enterovirus/rhinovirus). We did not find a relationship between CARV recovery from respiratory specimens and the primary endpoint (hazard ratio 0.64 [95% confidence interval: 0.25-1.59], P = .335) or between CARV and the development of alloimmune or autoimmune humoral or cellular responses. These findings raise the possibility that the immunologic impact of CARV following pediatric lung transplant is different than that observed in adults.

Community-Acquired Respiratory Viruses in Transplant Patients: Diversity, Impact, Unmet Clinical Needs

Patients undergoing solid-organ transplantation (SOT) or allogeneic hematopoietic cell transplantation (HCT) are at increased risk for infectious complications. Community-acquired respiratory viruses (CARVs) pose a particular challenge due to the frequent exposure pre-, peri-, and posttransplantation. Although influenza A and B viruses have a top priority regarding prevention and treatment, recent molecular diagnostic tests detecting an array of other CARVs in real time have dramatically expanded our knowledge about the epidemiology, diversity, and impact of CARV infections in the general population and in allogeneic HCT and SOT patients. These data have demonstrated that non-influenza CARVs independently contribute to morbidity and mortality of transplant patients. However, effective vaccination and antiviral treatment is only emerging for non-influenza CARVs, placing emphasis on infection control and supportive measures. Here, we review the current knowledge about CARVs in SOT and allogeneic HCT patients to better define the magnitude of this unmet clinical need and to discuss some of the lessons learned from human influenza virus, respiratory syncytial virus, parainfluenzavirus, rhinovirus, coronavirus, adenovirus, and bocavirus regarding diagnosis, prevention, and treatment.