Cytomegalovirus replication within the lung allograft is associated with bronchiolitis obliterans syndrome

Advances in lung transplantation: 60 years on

Lung transplantation is a well-established treatment for advanced lung disease, improving survival and quality of life. Over the last 60 years all aspects of lung transplantation have evolved significantly and exponential growth in transplant volume. This has been particularly evident over the last decade with a substantial increase in lung transplant numbers as a result of innovations in donor utilization procurement, including the use donation after circulatory death and ex-vivo lung perfusion organs. Donor lungs have proved to be surprisingly robust, and therefore the donor pool is actually larger than previously thought. Parallel to this, lung transplant outcomes have continued to improve with improved acute management as well as microbiological and immunological insights and innovations. The management of lung transplant recipients continues to be complex and heavily dependent on a tertiary care multidisciplinary paradigm. Whilst long term outcomes continue to be limited by chronic lung allograft dysfunction improvements in diagnostics, mechanistic understanding and evolutions in treatment paradigms have all contributed to a median survival that in some centres approaches 10 years. As ongoing studies build on developing novel approaches to diagnosis and treatment of transplant complications and improvements in donor utilization more individuals will have the opportunity to benefit from lung transplantation. As has always been the case, early referral for transplant consideration is important to achieve best results.

Letermovir prophylaxis for cytomegalovirus in lung-transplant recipients: a comprehensive study with literature review of off-label use and real-world experiences

Letermovir, initially approved for cytomegalovirus (CMV) prophylaxis in hematopoietic stem-cell transplantation, has gained attention for off-label use in lung-transplant (LTx) recipients. Given the high susceptibility of LTx recipients to CMV infection, this study explores the effectiveness and safety of letermovir prophylaxis. A retrospective analysis of using letermovir for LTx recipients at Tohoku University Hospital (January 2000 to November 2023) was conducted. Case summaries from other Japanese transplant centers and a literature review were included. Six cases at Tohoku University Hospital and one at Kyoto University Hospital were identified. Prophylactic letermovir use showed positive outcomes in managing myelosuppression and preventing CMV replication. The literature review supported the safety of letermovir in high-risk LTx recipients. Despite limited reports, our findings suggest letermovir's potential as prophylaxis for LTx recipients intolerant to valganciclovir. Safety, especially in managing myelosuppression, positions letermovir as a promising option. However, careful consideration is important in judiciously integrating letermovir into the treatment protocol.

Impulse Oscillometry Versus Spirometry to Detect Bronchiolitis Obliterans Syndrome in Bilateral Lung Transplant Recipients: A Prospective Diagnostic Study

BACKGROUND

Chronic lung allograft dysfunction (CLAD), and especially bronchiolitis obliterans syndrome (BOS), remain dominant causes of morbidity and mortality after lung transplantation. Interest is growing in the forced oscillation technique, of which impulse oscillometry (IOS) is a form, as a tool to improve our understanding of these disorders. However, data remain limited and no longitudinal studies have been published, meaning there is no information regarding any capacity IOS may have for the early detection of CLAD.

METHODS

We conducted a prospective longitudinal study enrolling a consecutive sample of adult bilateral lung transplant recipients with healthy lung allografts or CLAD and performed ongoing paired IOS and spirometry tests on a clinically determined basis. We assessed for correlations between IOS and spirometry and examined any predictive value either modality may hold for the early detection of BOS.

RESULTS

We enrolled 91 patients and conducted testing for 43 mo, collecting 558 analyzable paired IOS and spirometry tests, with a median of 9 tests per subject (interquartile range, 5-12) and a median testing interval of 92 d (interquartile range, 62-161). Statistically significant moderate-to-strong correlations were demonstrated between all IOS parameters and spirometry, except resistance at 20 Hz, which is a proximal airway measure. No predictive value for the early detection of BOS was found for IOS or spirometry.

CONCLUSIONS

This study presents the first longitudinal data from IOS after lung transplantation and adds considerably to the growing literature, showing unequivocal correlations with spirometry but failing to demonstrate a predictive value for BOS.

Prevention of Cytomegalovirus Infection in Solid Organ Transplant Recipients: Guidelines by the Korean Society of Infectious Diseases and the Korean Society for Transplantation

Cytomegalovirus (CMV) is the most important opportunistic viral pathogen in solid organ transplant (SOT) recipients. The Korean guideline for the prevention of CMV infection in SOT recipients was developed jointly by the Korean Society for Infectious Diseases and the Korean Society of Transplantation. CMV serostatus of both donors and recipients should be screened before transplantation to best assess the risk of CMV infection after SOT. Seronegative recipients receiving organs from seropositive donors face the highest risk, followed by seropositive recipients. Either antiviral prophylaxis or preemptive therapy can be used to prevent CMV infection. While both strategies have been demonstrated to prevent CMV infection post-transplant, each has its own advantages and disadvantages. CMV serostatus, transplant organ, other risk factors, and practical issues should be considered for the selection of preventive measures. There is no universal viral load threshold to guide treatment in preemptive therapy. Each institution should define and validate its own threshold. Valganciclovir is the favored agent for both prophylaxis and preemptive therapy. The evaluation of CMV-specific cell-mediated immunity and the monitoring of viral load kinetics are gaining interest, but there was insufficient evidence to issue recommendations. Specific considerations on pediatric transplant recipients are included.

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.

Association between cytomegalovirus viremia and long-term outcomes in lung transplant recipients

Although cytomegalovirus (CMV) viremia/DNAemia has been associated with reduced survival after lung transplantation, its association with chronic lung allograft dysfunction (CLAD) and its phenotypes is unclear. We hypothesized that, in a modern era of CMV prophylaxis, CMV DNAemia would still remain associated with death, but also represent a risk factor for CLAD and specifically restrictive allograft syndrome (RAS)/mixed phenotype. This was a single-center retrospective cohort study of all consecutive adult, first, bilateral-/single-lung transplants done between 2010-2016, consisting of 668 patients. Risks for death/retransplantation, CLAD, or RAS/mixed, were assessed by adjusted cause-specific Cox proportional-hazards models. CMV viral load (VL) was primarily modeled as a categorical variable: undetectable, detectable to 999, 1000 to 9999, and ≥10 000 IU/mL. In multivariable models, CMV VL was significantly associated with death/retransplantation (≥10 000 IU/mL: HR = 2.65 [1.78-3.94]; P < .01), but was not associated with CLAD, whereas CMV serostatus mismatch was (D+R-: HR = 2.04 [1.30-3.21]; P < .01). CMV VL was not associated with RAS/mixed in univariable analysis. Secondary analyses with a 7-level categorical or 4-level ordinal CMV VL confirmed similar results. In conclusion, CMV DNAemia is a significant risk factor for death/retransplantation, but not for CLAD or RAS/mixed. CMV serostatus mismatch may have an impact on CLAD through a pathway independent of DNAemia.

Herpes Virus Infection in Lung Transplantation: Diagnosis, Treatment and Prevention Strategies

Lung transplantation is an ultimate treatment option for some end-stage lung diseases; due to the intense immunosuppression needed to reduce the risk of developing acute and chronic allograft failure, infectious complications are highly incident. Viral infections represent nearly 30% of all infectious complications, with herpes viruses playing an important role in the development of acute and chronic diseases. Among them, cytomegalovirus (CMV) is a major cause of morbidity and mortality, being associated with an increased risk of chronic lung allograft failure. Epstein-Barr virus (EBV) is associated with transformation of infected B cells with the development of post-transplantation lymphoproliferative disorders (PTLDs). Similarly, herpes simplex virus (HSV), varicella zoster virus and human herpesviruses 6 and 7 can also be responsible for acute manifestations in lung transplant patients. During these last years, new, highly sensitive and specific diagnostic tests have been developed, and preventive and prophylactic strategies have been studied aiming to reduce and prevent the incidence of these viral infections. In this narrative review, we explore epidemiology, diagnosis and treatment options for more frequent herpes virus infections in lung transplant patients.

Cytomegalovirus Immunity Assays Predict Viremia but not Replication Within the Lung Allograft

Cytomegalovirus (CMV) infection causes significant morbidity and mortality in lung transplant recipients. Current guidelines use pretransplant donor and recipient CMV serostatus to predict the risk of subsequent CMV replication and length of antiviral prophylaxis. Immunological monitoring may better inform the risk of CMV infection in patients, thereby allowing for improved tailoring of antiviral prophylaxis. In this study, we compared 2 commercially available assays, the QuantiFERON-CMV (QFN-CMV) and T-Track-CMV (enzyme-linked immunosorbent spot assay), to predict the risk of CMV disease in lung transplant recipients.

Methods

We performed CMV immunity assays on 32 lung transplant recipients at risk of CMV disease as defined by serostatus (CMV-seropositive recipients, n = 26; or CMV-seronegative lung transplant recipient receiving a CMV-seropositive donor organ, n = 6). QFN-CMV and T-Track were performed on peripheral blood mononuclear cells, and episodes of CMV replication in both serum and bronchoalveolar lavage were found to be correlated to the CMV immune assays. The predictive ability of the assays was determined using Kaplan-Meier curves.

Results

There was a degree of concordance between tests, with 44% of recipients positive for both tests and 28% negative for both tests; however, test results were discordant in 28% of cases. A negative result in either the QFN-CMV (P < 0.01) or T-Track (P < 0.05) assays was obtained in a significantly higher number of recipients who experienced CMV replication in the blood. Using these assays together gave higher predictability of CMV replication, with only 1 recipient experiencing CMV replication in the blood who obtained a positive test result for both assays. Neither assay was able to predict recipients who experienced CMV replication in the lung allograft.

Conclusions

Our study demonstrates that CMV immunity assays can predict viremia; however, the lack of association with allograft infection suggests that CMV-specific T-cell immunity in the circulation is not associated with the control of CMV replication within the transplanted lung allograft.

Infection induces tissue-resident memory NK cells that safeguard tissue health

Tissue health is dictated by the capacity to respond to perturbations and then return to homeostasis. Mechanisms that initiate, maintain, and regulate immune responses in tissues are therefore essential. Adaptive immunity plays a key role in these responses, with memory and tissue residency being cardinal features. A corresponding role for innate cells is unknown. Here, we have identified a population of innate lymphocytes that we term tissue-resident memory-like natural killer (NKRM) cells. In response to murine cytomegalovirus infection, we show that circulating NK cells were recruited in a CX3CR1-dependent manner to the salivary glands where they formed NKRM cells, a long-lived, tissue-resident population that prevented autoimmunity via TRAIL-dependent elimination of CD4+ T cells. Thus, NK cells develop adaptive-like features, including long-term residency in non-lymphoid tissues, to modulate inflammation, restore immune equilibrium, and preserve tissue health. Modulating the functions of NKRM cells may provide additional strategies to treat inflammatory and autoimmune diseases.

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.

Acute Rejection and Chronic Lung Allograft Dysfunction: Obstructive and Restrictive Allograft Dysfunction

Lung transplantation is an established treatment of well-selected patients with end-stage respiratory diseases. However, lung transplant recipients have the highest rates of acute and chronic rejection among transplanted solid organs. Owing to ongoing alloimmune recognition and associated immune-driven airway/vascular remodeling, precipitated by multifactorial, endogenous or exogenous, post-transplant injuries to the bronchovascular axis of the secondary pulmonary lobule, most lung transplant recipients will suffer from a pathophysiological decline of their allograft, either functionally and/or structurally. This review discusses current knowledge, barriers, and gaps in acute cellular rejection and chronic lung allograft dysfunction-the greatest impediment to long-term post-transplant survival.

Changes in HCMV immune cell frequency and phenotype are associated with chronic lung allograft dysfunction

Background

Human cytomegalovirus (HCMV) infection is common and often severe in lung transplant recipients (LTRs), and it is a risk factor associated with chronic lung allograft dysfunction (CLAD). The complex interplay between HCMV and allograft rejection is still unclear. Currently, no treatment is available to reverse CLAD after diagnosis, and the identification of reliable biomarkers that can predict the early development of CLAD is needed. This study investigated the HCMV immunity in LTRs who will develop CLAD.

Methods

This study quantified and phenotyped conventional (HLA-A2pp65) and HLA-E-restricted (HLA-EUL40) anti-HCMV CD8⁺ T (CD8 T) cell responses induced by infection in LTRs developing CLAD or maintaining a stable allograft. The homeostasis of immune subsets (B, CD4T, CD8 T, NK, and γδT cells) post-primary infection associated with CLAD was also investigated.

Results

At M18 post-transplantation, HLA-EUL40 CD8 T responses were less frequently found in HCMV⁺ LTRs (21.7%) developing CLAD (CLAD) than in LTRs (55%) keeping a functional graft (STABLE). In contrast, HLA-A2pp65 CD8 T was equally detected in 45% of STABLE and 47.8% of CLAD LTRs. The frequency of HLA-EUL40 and HLA-A2pp65 CD8 T among blood CD8 T cells shows lower median values in CLAD LTRs. Immunophenotype reveals an altered expression profile for HLA-EUL40 CD8 T in CLAD patients with a decreased expression for CD56 and the acquisition of PD-1. In STABLE LTRs, HCMV primary infection causes a decrease in B cells and inflation of CD8 T, CD57⁺/NKG2C⁺ NK, and δ2^-γδT cells. In CLAD LTRs, the regulation of B, total CD8 T, and δ2⁺γδT cells is maintained, but total NK, CD57⁺/NKG2C⁺ NK, and δ2^-γδT subsets are markedly reduced, while CD57 is overexpressed across T lymphocytes.

Conclusions

CLAD is associated with significant changes in anti-HCMV immune cell responses. Our findings propose that the presence of dysfunctional HCMV-specific HLA-E-restricted CD8 T cells together with post-infection changes in the immune cell distribution affecting NK and γδT cells defines an early immune signature for CLAD in HCMV⁺ LTRs. Such a signature may be of interest for the monitoring of LTRs and may allow an early stratification of LTRs at risk of CLAD.

Human cytomegalovirus strain diversity and dynamics reveal the donor lung as a major contributor after transplantation

Mixed human cytomegalovirus (HCMV) strain infections are frequent in lung transplant recipients (LTRs). To date, the influence of the donor (D) and recipient (R) HCMV serostatus on intra-host HCMV strain composition and viral population dynamics after transplantation is only poorly understood. Here, we investigated ten pre-transplant lungs from HCMV-seropositive donors and 163 sequential HCMV-DNA-positive plasma and bronchoalveolar lavage samples from fifty LTRs with multiviremic episodes post-transplantation. The study cohort included D+R+ (38 per cent), D+R- (36 per cent), and D-R+ (26 per cent) patients. All samples were subjected to quantitative genotyping by short amplicon deep sequencing, and twenty-four of them were additionally PacBio long-read sequenced for genotype linkages. We find that D+R+ patients show a significantly elevated intra-host strain diversity compared to D+R- and D-R+ patients (P = 0.0089). Both D+ patient groups display significantly higher viral population dynamics than D- patients (P = 0.0061). Five out of ten pre-transplant donor lungs were HCMV DNA positive, whereof three multiple HCMV strains were detected, indicating that multi-strain transmission via lung transplantation is likely. Using long reads, we show that intra-host haplotypes can share distinctly linked genotypes, which limits overall intra-host diversity in mixed infections. Together, our findings demonstrate donor-derived strains as the main source of increased HCMV strain diversity and dynamics post-transplantation. These results foster strategies to mitigate the potential transmission of the donor strain reservoir to the allograft, such as ex vivo delivery of HCMV-selective immunotoxins prior to transplantation to reduce latent HCMV.

Human cytomegalovirus: a survey of end-organ diseases and diagnostic challenges in solid organ transplant recipients

PURPOSE OF REVIEW

Human cytomegalovirus (CMV) infection is one of the most important infectious complications in solid organ transplant (SOT) recipients, leading to significant morbidity and mortality. Therefore, early detection and prompt treatment are imperative to improve transplant outcomes. This article highlights the clinical characteristics of the most common CMV end-organ diseases in SOT recipients and their diagnostic modalities and challenges.

RECENT FINDINGS

CMV can cause a variety of end-organ diseases in SOT recipients. Although CMV nucleic acid amplification by polymerase chain reaction (PCR) is frequently employed to detect CMV reactivation or infection, its predictive value for various CMV end-organ diseases remains uncertain. Given the limitation of PCR or other noninvasive tests, confirmation of CMV end-organ disease may require tissue biopsy, which may not be feasible or available, or may cause untoward complications.

SUMMARY

The utility of PCR to diagnose CMV end-organ disease is limited. As CMV can infect any organ system(s), clinicians caring for SOT recipients need to maintain vigilance for any signs and symptoms of end-organ disease to allow early recognition and prompt treatment. Invasive procedures might be needed to confirm the diagnosis and minimize the empirical use of antiviral therapy that may have substantial drug toxicities.

Aging Affects the Role of Myeloid-Derived Suppressor Cells in Alloimmunity

Myeloid-derived suppressor cells (MDSC) are defined as a group of myeloid cells with potent immunoregulatory functions that have been shown to be involved in a variety of immune-related diseases including infections, autoimmune disorders, and cancer. In organ transplantation, MDSC promote tolerance by modifying adaptive immune responses. With aging, however, substantial changes occur that affect immune functions and impact alloimmunity. Since the vast majority of transplant patients are elderly, age-specific modifications of MDSC are of relevance. Furthermore, understanding age-associated changes in MDSC may lead to improved therapeutic strategies. Here, we provide a comprehensive update on the effects of aging on MDSC and discuss potential consequences on alloimmunity.

Cytomegalovirus Infection Is Associated with Development of Chronic Lung Allograft Dysfunction

Background

Cytomegalovirus (CMV) is the major and most common opportunistic infection complicating lung transplant (LTX). The aim of this study was to analyse the epidemiological aspects of CMV infection in lung transplant patients subject to a pre-emptive anti-CMV approach and to study the impact of this infection on lung transplant outcome, in terms of onset of chronic lung allograft dysfunction (CLAD).

Methods

This single-centre retrospective study enrolled 87 LTX patients (median age 55.81 years; 41 females, 23 single LTX, 64 bilateral LTX). All patients were managed with a pre-emptive anti-CMV approach. The incidences of the first episode of CMV infection, 1, 3, 6 and 12 months after LTX, were 12.64%, 44.26%, 50.77% and 56.14%. A median interval of 41 days elapsed between LTX and the first episode of CMV infection. The median blood load of CMV-DNA at diagnosis was 20,385 cp/ml; in 67.64% of cases, it was also the peak value. Patients who had at least one episode had shorter CLAD-free survival. Patients who had three or more episodes of CMV infection had the worst outcome.

Results

CMV infection was confirmed to be a common event in lung transplant patients, particularly in the first three months after transplant. It had a negative impact on transplant outcome, being a major risk factor for CLAD. The hypothesis that lower viral replication thresholds may increase the risk of CLAD is interesting and deserves further investigation.

Ex vivo treatment of cytomegalovirus in human donor lungs using a novel chemokine-based immunotoxin

BACKGROUND

Transmission of latent human cytomegalovirus (HCMV) via organ transplantation with post-transplant viral reactivation is extremely prevalent and results in substantial adverse impact on outcomes. Therapies targeting the latent reservoir within the allograft to mitigate viral transmission would represent a major advance. Here, we delivered an immunotoxin (F49A-FTP) that targets and kills latent HCMV aiming at reducing the HCMV reservoir from donor lungs using ex-vivo lung perfusion (EVLP).

METHODS

HCMV seropositive human lungs were placed on EVLP alone or EVLP + 1mg/L of F49A-FTP for 6 hours (n = 6, each). CD14+ monocytes isolated from biopsies pre and post EVLP underwent HCMV reactivation assay designed to evaluate viral reactivation capacity. Off-target effects of F49A-FTP were studied evaluating cell death markers of CD34+ and CD14+ cells using flow cytometry. Lung function on EVLP and inflammatory cytokine production were evaluated as safety endpoints.

RESULTS

We demonstrate that lungs treated ex-vivo with F49A-FTP had a significant reduction in HCMV reactivation compared to controls, suggesting successful targeting of latent virus (76% median reduction in F49A-FTP vs 15% increase in controls, p = 0.0087). Furthermore, there was comparable cell death rates of the targeted cells between both groups, suggesting no off-target effects. Ex-vivo lung function was stable over 6 hours and no differences in key inflammatory cytokines were observed demonstrating safety of this novel treatment.

CONCLUSIONS

Ex-vivo F49A-FTP treatment of human lungs targets and kills latent HCMV, markedly attenuating HCMV reactivation. This approach demonstrates the first experiments targeting latent HCMV in a donor organ with promising results towards clinical translation.

Cytomegalovirus Exposure and the Risk of Overall Infection After Kidney Transplantation: A Cohort Study on the Indirect Effects Attributable to Viral Replication

Previous reports hypothesized that cytomegalovirus (CMV) may predispose to non-CMV infection after kidney transplantation (KT). We analysed the incidence of non-CMV infection (overall, bacterial and opportunistic) in 291 KT recipients according to the previous development of any level or high-level (≥1,000 IU/ml) CMV viremia. Exposure to CMV replication was assessed throughout fixed intervals covering first the 30, 90, 180 and 360 post-transplant days (cumulative exposure) and non-overlapping preceding periods (recent exposure). Adjusted Cox models were constructed for each landmark analysis. Overall, 67.7 and 50.5% patients experienced non-CMV and CMV infection, respectively. Patients with cumulative CMV exposure had higher incidence of non-CMV infection beyond days 30 (p-value = 0.002) and 90 (p-value = 0.068), although these associations did not remain after multivariable adjustment. No significant associations were observed for the remaining landmark models (including those based on high-level viremia or recent CMV exposure), or when bacterial and opportunistic infection were separately analysed. There were no differences in viral kinetics (peak CMV viremia and area under curve of CMV viral load) either. Our findings do not support the existence of an independent association between previous CMV exposure and the overall risk of post-transplant infection, although results might be affected by power limitations.

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.

Management of Multidrug Resistant Infections in Lung Transplant Recipients with Cystic Fibrosis

Cystic fibrosis (CF) is an inherited multisystem disease characterised by bronchiectasis and chronic respiratory infections which eventually cause end stage lung disease. Lung transplantation (LTx) is a well-established treatment option for patients with CF-associated lung disease, improving survival and quality of life. Navigating recurrent infections in the setting of LTx is often difficult, where immune suppression must be balanced against the constant threat of infection. Sepsis/infections are one of the major contributors to post-LTx mortality and multiresistant organisms (eg, Burkholderia cepacia complex, Mycobacterium abscessus complex, Scedosporium spp. and Lomentospora spp.) pose a significant threat to survival. This review will summarize current and novel therapies to assist with the management of multiresistant bacterial, mycobacterial, viral and fungal infections which threaten the CF LTx cohort.

Use of anti-CMV immunoglobulins in lung transplant recipients: The French experience

RATIONAL

Pending the authorization of new anti-CMV drugs with fewer adverse effects, exploring the possibilities offered by CMV immunoglobulins (CMVIG) seems necessary. In France, access to CMVIG requires official authorization by the national Health authority and is restricted to second line rescue therapy for CMV infection/disease. The aim of this multicenter retrospective study is to describe the indications and clinical situations that justified its use in France.

METHODS

A multicenter retrospective study included 22 lung transplant patients over a 3-year period. Data on clinical indication, tolerance and efficacy were collected.

RESULTS

The main indication for CMVIG initiation, which was documented in 17 of them (82%) was complex clinical situations resulting from side effects to antiviral drug. CMVIG indication was documented as treatment for 15 patients (68%) and as a secondary prophylaxis for 7 patients (32%). Only one side effect (pruritus during infusion with no anaphylactic symptoms) attributable to CMVIG was reported. After CMVIG initiation, no recurrence of infection or disease was observed during a median follow-up of 174 (12-682) days after treatment initiation for respectively 68% and 66% of the patients.

CONCLUSION

This study describes an unusual indication of CMVIG use as a last resort treatment in complex situations, based on clinical needs. CMVIG could be useful to change the course of CMV infection with minimal adverse effects or comorbidity.

Abnormal one-year post-lung transplant spirometry is a significant predictor of increased mortality and chronic lung allograft dysfunction

BACKGROUND

The prognostic value of evaluating spirometry at a fixed time point using standardized population reference has not previously been evaluated. Our aim was to assess the association between spirometric phenotype at 12 months (Spiro_12M), survival and incidence of chronic lung allograft dysfunction (CLAD) in bilateral lung transplant recipients.

METHODS

We conducted a retrospective cohort study of bilateral lung transplant recipients transplanted between January 2003 and September 2012. We defined Spiro_12M as the mean of the 2 prebronchodilator FEV₁ measurements 12-month post-transplant. Normal spirometry was defined as FEV₁/FVC ≥0.7 and FEV1≥80% and FVC≥80% predicted population-based values for that recipient. Abnormal spirometry was defined as failure to attain normal function by 12-months. We used a Cox regression model to assess the association between Spiro_12M, survival, and CLAD. We used logistic regression to assess potential pretransplant donor and recipient factors associated with abnormal Spiro_12M RESULTS: One hundred and eleven (51%) lung transplant recipients normalized their Spiro_12M. Normal Spiro_12M was associated improved survival (hazard ratio [HR] 0.60, 95% confidence interval [CI] 0.41-0.88], p = 0.009. Each 10% decrement in FEV₁ increased the risk of death in a stepwise fashion. Additionally, CLAD was reduced in those with normal Spiro_12M (HR:0.65, 95%CI:0.46-0.92, p = 0.016). Donor smoking history (OR:2.93, 95% CI:1.21-7.09; p = 0.018) and mechanical ventilation time in hours (OR:1.03, 95% CI:1.004-1.05; p = 0.02) were identified as independent predictors of abnormal Spiro_12M.

CONCLUSIONS

Abnormal Spiro_12M is associated with increased mortality and the development of CLAD. The effect is dose dependent with increased dysfunction corresponding to increased risk. This assessment of phenotype at 12-months can easily be incorporated into standard of care.

Inferior outcomes in lung transplant recipients with serum Pseudomonas aeruginosa specific cloaking antibodies

BACKGROUND

Chronic Lung Allograft Dysfunction (CLAD) limits long-term survival following lung transplantation. Colonization of the allograft by Pseudomonas aeruginosa is associated with an increased risk of CLAD and inferior overall survival. Recent experimental data suggests that 'cloaking' antibodies targeting the O-antigen of the P. aeruginosa lipopolysaccharide cell wall (cAbs) attenuate complement-mediated bacteriolysis in suppurative lung disease.

METHODS

In this retrospective cohort analysis of 123 lung transplant recipients, we evaluated the prevalence, risk factors and clinical impact of serum cAbs following transplantation.

RESULTS

cAbs were detected in the sera of 40.7% of lung transplant recipients. Cystic fibrosis and younger age were associated with increased risk of serum cAbs (CF diagnosis, OR 6.62, 95% CI 2.83-15.46, p < .001; age at transplant, OR 0.69, 95% CI 0.59-0.81, p < .001). Serum cAbs and CMV mismatch were both independently associated with increased risk of CLAD (cAb, HR 4.34, 95% CI 1.91-9.83, p < .001; CMV mismatch (D+/R-), HR 5.40, 95% CI 2.36-12.32, p < .001) and all-cause mortality (cAb, HR 2.75, 95% CI 1.27-5.95, p = .010, CMV mismatch, HR 3.53, 95% CI 1.62-7.70, p = .002) in multivariable regression analyses.

CONCLUSIONS

Taken together, these findings suggest a potential role for 'cloaking' antibodies targeting P. aeruginosa LPS O-antigen in the immunopathogenesis of CLAD.

Acute Rejection in the Modern Lung Transplant Era

Acute cellular rejection (ACR) remains a common complication after lung transplantation. Mortality directly related to ACR is low and most patients respond to first-line immunosuppressive treatment. However, a subset of patients may develop refractory or recurrent ACR leading to an accelerated lung function decline and ultimately chronic lung allograft dysfunction. Infectious complications associated with the intensification of immunosuppression can also negatively impact long-term survival. In this review, we summarize the most recent evidence on the mechanisms, risk factors, diagnosis, treatment, and prognosis of ACR. We specifically focus on novel, promising biomarkers which are under investigation for their potential to improve the diagnostic performance of transbronchial biopsies. Finally, for each topic, we highlight current gaps in knowledge and areas for future research.

Chronic Lung Allograft Dysfunction: Evolving Concepts and Therapies

The primary factor that limits long-term survival after lung transplantation is chronic lung allograft dysfunction (CLAD). CLAD also impairs quality of life and increases the costs of medical care. Our understanding of CLAD continues to evolve. Consensus definitions of CLAD and the major CLAD phenotypes were recently updated and clarified, but it remains to be seen whether the current definitions will lead to advances in management or impact care. Understanding the potential differences in pathogenesis for each CLAD phenotype may lead to novel therapeutic strategies, including precision medicine. Recognition of CLAD risk factors may lead to earlier interventions to mitigate risk, or to avoid risk factors all together, to prevent the development of CLAD. Unfortunately, currently available therapies for CLAD are usually not effective. However, novel therapeutics aimed at both prevention and treatment are currently under investigation. We provide an overview of the updates to CLAD-related terminology, clinical phenotypes and their diagnosis, natural history, pathogenesis, and potential strategies to treat and prevent CLAD.

Utility of CMV-Specific Immune Monitoring for the Management of CMV in Solid Organ Transplant Recipients: A Clinical Update

Cytomegalovirus (CMV) is one of the most important opportunistic infections in solid organ transplant (SOT) recipients. However, current techniques used to predict risk for CMV infection fall short. CMV-specific cell mediated immunity (CMI) plays an important role in protecting against CMV infection. There is evidence that assays measuring CMV-CMI might better identify SOT recipients at risk of complications from CMV compared to anti-CMV IgG, which is our current standard of care. Here, we review recently published studies that utilize CMV-CMI, at various points before and after transplantation, to help predict risk and guide the management of CMV infection following organ transplantation. The evidence supports the use of these novel assays to help identify SOT recipients at increased risk and highlights the need for larger prospective trials evaluating these modalities in this high-risk population.

Lung microbiota predict chronic rejection in healthy lung transplant recipients: a prospective cohort study

BACKGROUND

Alterations in the respiratory microbiome are common in chronic lung diseases, correlate with decreased lung function, and have been associated with disease progression. The clinical significance of changes in the respiratory microbiome after lung transplant, specifically those related to development of chronic lung allograft dysfunction (CLAD), are unknown. The aim of this study was to evaluate the effect of lung microbiome characteristics in healthy lung transplant recipients on subsequent CLAD-free survival.

METHODS

We prospectively studied a cohort of lung transplant recipients at the University of Michigan (Ann Arbor, MI, USA). We analysed characteristics of the respiratory microbiome in acellular bronchoalveolar lavage fluid (BALF) collected from asymptomatic patients during per-protocol surveillance bronchoscopy 1 year after lung transplantation. For our primary endpoint, we evaluated a composite of development of CLAD or death at 500 days after the 1-year surveillance bronchoscopy. Our primary microbiome predictor variables were bacterial DNA burden (total 16S rRNA gene copies per mL of BALF, quantified via droplet digital PCR) and bacterial community composition (determined by bacterial 16S rRNA gene sequencing). Patients' lung function was followed serially at least every 3 months by spirometry, and CLAD was diagnosed according to International Society of Heart and Lung Transplant 2019 guidelines.

FINDINGS

We analysed BALF from 134 patients, collected during 1-year post-transplant surveillance bronchoscopy between Oct 21, 2005, and Aug 25, 2017. Within 500 days of follow-up from the time of BALF sampling, 24 (18%) patients developed CLAD, five (4%) died before confirmed development of CLAD, and 105 (78%) patients remained CLAD-free with complete follow-up. Lung bacterial burden was predictive of CLAD development or death within 500 days of the surveillance bronchoscopy, after controlling for demographic and clinical factors, including immunosuppression and bacterial culture results, in a multivariable survival model. This relationship was evident when burden was analysed as a continuous variable (per log₁₀ increase in burden, HR 2·49 [95% CI 1·38-4·48], p=0·0024) or by tertiles (middle vs lowest bacterial burden tertile, HR 4·94 [1·25-19·42], p=0·022; and highest vs lowest, HR 10·56 [2·53-44·08], p=0·0012). In patients who developed CLAD or died, composition of the lung bacterial community significantly differed to that in patients who survived and remained CLAD-free (on permutational multivariate analysis of variance, p=0·047 at the taxonomic level of family), although differences in community composition were associated with bacterial burden. No individual bacterial taxa were definitively associated with CLAD development or death.

INTERPRETATION

Among asymptomatic lung transplant recipients at 1-year post-transplant, increased lung bacterial burden is predictive of chronic rejection and death. The lung microbiome represents an understudied and potentially modifiable risk factor for lung allograft dysfunction.

FUNDING

US National Institutes of Health, Cystic Fibrosis Foundation, Brian and Mary Campbell and Elizabeth Campbell Carr research gift fund.

Lung Transplant Pathology: An Overview on Current Entities and Procedures

Alloimmune reactions are, besides various infections, the major cause for impaired lung allograft function following transplant. Acute cellular rejection is not only a major trigger of acute allograft failure but also contributes to development of chronic lung allograft dysfunction. Analogous to other solid organ transplants, acute antibody-mediated rejection has become a recognized entity in lung transplant pathology. Adequate sensitivity and specificity in the diagnosis of alloimmune reactions in the lung can only be achieved by synoptic analysis of histopathologic, clinical, and radiological findings together with serologic and microbiologic 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.

Advances in Human Lung Transplantation

Lung transplantation improves survival and quality of life in patients with advanced pulmonary disease. Over the past several decades, the volume of lung transplants has grown substantially, with increasing transplantation of older and acutely ill individuals facilitated by improved utilization and preservation of available donor organs. Other advances include improvements in the diagnosis and mechanistic understanding of frequent post-transplant complications, such as primary graft dysfunction, acute rejection, and chronic lung allograft dysfunction (CLAD). CLAD occurs as a result of the host immune response to the allograft and is the principal factor limiting long-term survival after lung transplantation. Two distinct clinical phenotypes of CLAD have emerged, bronchiolitis obliterans syndrome and restrictive allograft syndrome, and this distinction has enabled further understanding of underlying immune mechanisms. Building on these advances, ongoing studies are exploring novel approaches to diagnose, prevent, and treat CLAD. Such studies are necessary to improve long-term outcomes for lung transplant recipients.

Cytomegalovirus replication is associated with enrichment of distinct γδ T cell subsets following lung transplantation: A novel therapeutic approach?

BACKGROUND

Anti-viral treatments to control cytomegalovirus (CMV) after lung transplantation (LTx) are associated with toxicity and anti-viral resistance. Cellular immunotherapy with virus-specific cytotoxic T cells has yielded promising results but requires donor/recipient matching. γδ T cells are involved in anti-viral immunity and can recognize antigens independently of major histocompatibility complex molecules and may not require the same level of matching. We assessed the phenotype of circulating γδ T cells after LTx to identify the candidate populations for CMV immunotherapy.

METHODS

Peripheral blood mononuclear cells were isolated from lung transplant recipients before transplantation and at routine bronchoscopies after LTx. Patients were stratified by risk of CMV disease into moderate risk (recipient CMV seropositive, n = 15) or high risk (HR) (recipient CMV seronegative/donor CMV seropositive, n = 10). CMV replication was classified as polymerase chain reaction positive (>150 copies/ml) in blood and/or bronchoalveolar lavage within the first 18 months. The phenotype of γδ T cells was assessed by multicolor flow cytometry, and T-cell receptor (TCR) sequences were determined by deep sequencing.

RESULTS

In HR lung transplant recipients with CMV replication, we observed striking phenotypic changes in γδ T cells, marked by an increase in the proportion of effector Vδ1+ γδ T cells expressing the activating natural killer cell receptor NKG2C. Moreover, we observed a remarkable increase in TCR diversity.

CONCLUSIONS

NKG2C+ Vδ1+ γδ T cells were associated with CMV replication and may indicate their potential to control infection. As such, we propose that they could be a potential target for cellular therapy against CMV.

Sterile inflammation in thoracic transplantation

The life-saving benefits of organ transplantation can be thwarted by allograft dysfunction due to both infectious and sterile inflammation post-surgery. Sterile inflammation can occur after necrotic cell death due to the release of endogenous ligands [such as damage-associated molecular patterns (DAMPs) and alarmins], which perpetuate inflammation and ongoing cellular injury via various signaling cascades. Ischemia-reperfusion injury (IRI) is a significant contributor to sterile inflammation after organ transplantation and is associated with detrimental short- and long-term outcomes. While the vicious cycle of sterile inflammation and cellular injury is remarkably consistent amongst different organs and even species, we have begun understanding its mechanistic basis only over the last few decades. This understanding has resulted in the developments of novel, yet non-specific therapies for mitigating IRI-induced graft damage, albeit with moderate results. Thus, further understanding of the mechanisms underlying sterile inflammation after transplantation is critical for identifying personalized therapies to prevent or interrupt this vicious cycle and mitigating allograft dysfunction. In this review, we identify common and distinct pathways of post-transplant sterile inflammation across both heart and lung transplantation that can potentially be targeted.

Unexpectedly High Prevalence of Cytomegalovirus DNAemia in Older Children and Adolescents With Perinatally Acquired Human Immunodeficiency Virus Infection

Background

Older children and adolescents with perinatally acquired human immunodeficiency virus (PHIV) infection in Africa experience multiple comorbidities that are not typical of HIV-associated opportunistic infections, including growth impairment and chronic lung disease. We examined associations between plasma cytomegalovirus (CMV) DNA and lung function and growth.

Methods

Plasma CMV DNA loads were measured children aged 6–16 years with PHIV (n = 402) and HIV-uninfected controls (n = 224). The HIV-infected children were either newly diagnosed or known HIV infected and stable on antiretroviral therapy (ART) for >6 months. CMV DNA loads were measured using quantitative polymerase chain reaction. CMV DNAemia was modeled as a time-varying outcome using longitudinal mixed-effects logistic regression.

Results

At enrollment, CMV DNAemia ≥1000 copies/mL (defined as “clinically significant”) was detected in 5.8% of uninfected children, 14.7% of HIV-infected participants stable on ART, and 22.6% of HIV-infected ART-naive children (χ² = 23.8, P < .001). The prevalence of CMV DNAemia ≥1000 copies/mL was associated with CD4 counts <350 cells/µL. Among HIV-infected ART-naive children, the presence of CMV DNAemia of ≥1000 copies/mL was independently associated with reduced lung function (adjusted odds ratio [aOR] = 3.23; 95% confidence interval [CI], 1.23–8.46; P = .017). Among ART-treated children, stunting was associated with CMV DNAemia of ≥1000 copies/mL (aOR = 2.79; 95% CI, 0.97–8.02; P = .057).

Conclusions

Clinically significant levels of CMV DNAemia were common in older children with PHIV, even those on ART, suggesting a role for inadequately controlled CMV infection in the pathogenesis of PHIV comorbidities in Africa.

Tailored combined cytomegalovirus management in lung transplantation: a retrospective analysis

BACKGROUND

There is no univocal prophylactic regimen to prevent cytomegalovirus (CMV) infection/disease in lung transplantation (LT) recipients. The aim of this study is to evaluate short-term clinical outcomes of a tailored combined CMV management approach.

METHODS

After 1-year follow up, 43 LT patients receiving combined CMV prophylaxis with antiviral agents and CMV-specific IgG were evaluated in a retrospective observational study. Systemic and lung viral infections were investigated by molecular methods on a total of 1134 whole blood and 167 bronchoalveolar lavage (BAL) and biopsy specimens. CMV immunity was assessed by ELISPOT assay. Clinical and therapeutic data were also evaluated.

RESULTS

We found 2/167 cases of CMV pneumonia (1.2%), both in the donor-positive/recipient-positive (D⁺/R⁺) population, and 51/167 cases of CMV pulmonary infection (BAL positivity 30.5%). However, only 32/167 patients (19.1%) were treated due to their weak immunological response at CMV ELISPOT assay. Viremia ⩾100,000 copies/mL occurred in 33/1134 specimens (2.9%). Regarding CMV-serological matching (D/R), the D⁺/R^- population had more CMV viremia episodes (p < 0.05) and fewer viremia-free days (p < 0.001).

CONCLUSIONS

Compared to previous findings, our study shows a lower incidence of CMV pneumonia and viremia despite the presence of a substantial CMV load. In addition, our findings further confirm the D⁺/R^- group to be a high-risk population for CMV viremia. Overall, a good immunological response seems to protect patients from CMV viremia and pneumonia but not from CMV alveolar replication. The reviews of this paper are available via the supplemental material section.

Extending cytomegalovirus prophylaxis in high-risk (D+/R-) lung transplant recipients from 6 to 9 months reduces cytomegalovirus disease: A retrospective study

RATIONALE

Cytomegalovirus (CMV)-seronegative recipients receiving a seropositive allograft (D+/R-) are at a high risk of developing CMV disease. Our program increased the duration of CMV prophylaxis from 6 to 9 months in May 2013. Here, we present the impact on the incidence of CMV infection, disease, side effects, rejection, and other factors.

METHODS

Retrospective cohort of 241 CMV (D+/R-) patients transplanted between January 1, 2008, and December 31, 2017. Blood CMV testing was done according to protocol. All patients received ganciclovir/valganciclovir as prophylaxis. We compared the incidence and timing of CMV infection and disease up to 6 months after cessation of prophylaxis between patients who received 9 months (May 2013 onwards) and a historical control group who received 6 months of prophylaxis (prior to May 2013). CMV infection was defined as detectable CMV viremia in the absence of symptoms. CMV disease was defined as CMV syndrome or tissue-invasive disease. Side effects of prophylaxis and CMV resistance were recorded.

RESULTS

A total of 116 patients were included in the 6-month group and 125 in the 9-month group. The extended 9-month CMV prophylaxis delayed the onset of CMV infection (median time to CMV infection after lung transplantation 295 vs 353 days, P < .01) but did not significantly reduce the incidence of CMV infection (65% vs 64%, P = .06, log-rank). The 9-month prophylaxis delayed the onset and decreased the incidence of CMV disease from 50% in the 6-month group to 42% (P = .02 log-rank). There was no difference in the rate of adverse effects (leukopenia in 32% in both groups, P = .53) or development of CMV resistance between the two groups (4 cases in both groups, P = .92). There were no significant differences in overall survival or the rate of chronic lung allograft dysfunction between the groups.

CONCLUSIONS

Extending duration of CMV prophylaxis from 6 to 9 months resulted in a delayed and decreased incidence of CMV disease in our lung transplant population. The absolute risk reduction achieved by extended CMV prophylaxis was 8%. The incidence of CMV infection, and ganciclovir resistance and side effects were similar between the two groups. Our results suggest that extending CMV prophylaxis in the highest risk CMV D+/R- group is effective in reducing CMV disease.

Emerging biomarkers in chronic lung allograft dysfunction

Introduction: Lung transplantation remains an important treatment for patients with end stage lung disease. Chronic lung allograft dysfunction (CLAD) remains the greatest limiting factor for long term survival. As the diagnosis of CLAD is based on pulmonary function tests, significant lung injury is required before a diagnosis is feasible, likely when irreversible damage has already occurred. Therefore, research is ongoing for early CLAD recognition, with biomarkers making up a substantial amount of this research.Areas covered: The purpose of this review is to describe available biomarkers, focusing on those which aid in predicting CLAD and distinguishing between different CLAD phenotypes. We describe biomarkers presenting in bronchial alveolar lavage (BAL) as well as circulating in peripheral blood, both of which offer an appealing alternative to lung biopsy.Expert opinion: Development of CLAD involves complex, multiple immune and nonimmune mechanisms. Therefore, evaluation of potential CLAD biomarkers serves a dual purpose: clinically, the goal remains early detection and identification of patients at increased risk. Simultaneously, biomarkers offer insight into the different mechanisms involved in the pathophysiology of CLAD, leading to the development of possible interventions. The ultimate goal is the development of both preventive and early intervention strategies for CLAD to improve the overall survival of our lung transplant recipients.

Bronchiolitis obliterans syndrome and restrictive allograft syndrome after lung transplantation: why are there two distinct forms of chronic lung allograft dysfunction?

Bronchiolitis obliterans syndrome (BOS) had been considered to be the representative form of chronic rejection or chronic lung allograft dysfunction (CLAD) after lung transplantation. In BOS, small airways are affected by chronic inflammation and obliterative fibrosis, whereas peripheral lung tissue remains relatively intact. However, recognition of another form of CLAD involving multiple tissue compartments in the lung, termed restrictive allograft syndrome (RAS), raised a fundamental question: why there are two phenotypes of CLAD? Increasing clinical and experimental data suggest that RAS may be a prototype of chronic rejection after lung transplantation involving both cellular and antibody-mediated alloimmune responses. Some cases of RAS are also induced by fulminant general inflammation in lung allografts. However, BOS involves alloimmune responses and the airway-centered disease process can be explained by multiple mechanisms such as external alloimmune-independent stimuli (such as infection, aspiration and air pollution), exposure of airway-specific autoantigens and airway ischemia. Localization of immune responses in different anatomical compartments in different phenotypes of CLAD might be associated with lymphoid neogenesis or the de novo formation of lymphoid tissue in lung allografts. Better understanding of distinct mechanisms of BOS and RAS will facilitate the development of effective preventive and therapeutic strategies of CLAD.

The role of innate immunity in the long-term outcome of lung transplantation

Long-term survival after lung transplantation remains suboptimal due to chronic lung allograft dysfunction (CLAD), a progressive scarring process affecting the graft. Although anti-donor alloimmunity is central to the pathogenesis of CLAD, its underlying mechanisms are not fully elucidated and it is neither preventable nor treatable using currently available immunosuppression. Recent evidence has shown that innate immune stimuli are fundamental to the development of CLAD. Here, we examine long-standing assumptions and new concepts linking innate immune activation to late lung allograft fibrosis.

Dectin-1 genetic deficiency predicts chronic lung allograft dysfunction and death

BACKGROUNDInnate immune activation impacts lung transplant outcomes. Dectin-1 is an innate receptor important for pathogen recognition. We hypothesized that genotypes reducing dectin-1 activity would be associated with infection, graft dysfunction, and death in lung transplant recipients.METHODSWe assessed the rs16910526 CLEC7A gene polymorphism Y238X, which results in dectin-1 truncation, in 321 lung allograft recipients at a single institution and in 1,129 lung allograft recipients in the multicenter Lung Transplant Outcomes Group (LTOG) cohort. Differences in dectin-1 mRNA, cytokines, protein levels, immunophenotypes, and clinical factors were assessed.RESULTSY238X carriers had decreased dectin-1 mRNA expression (P = 0.0001), decreased soluble dectin-1 protein concentrations in bronchoalveolar lavage (P = 0.008) and plasma (P = 0.04), and decreased monocyte surface dectin-1 (P = 0.01) compared with wild-type subjects. Y238X carriers had an increased risk of fungal pathogens (HR 1.17, CI 1.0-1.4), an increased risk of graft dysfunction or death (HR 1.6, CI 1.0-2.6), as well increased mortality in the UCSF cohort (HR 1.8, CI 1.1-3.8) and in the LTOG cohort (HR 1.3, CI 1.1-1.6), compared with wild-type CLEC7A subjects.CONCLUSIONIncreased rates of graft dysfunction and death associated with this dectin-1 polymorphism may be amplified by immunosuppression that drives higher fungal burden from compromised pathogen recognition.FUNDINGThe UCSF Nina Ireland Program for Lung Health Innovative Grant program, the Clinical Sciences Research & Development Service of the VA Office of Research and Development, and the Joel D. Cooper Career Development Award from the International Society for Heart and Lung Transplantation.

A Randomized Study of Quantiferon CMV-directed Versus Fixed-duration Valganciclovir Prophylaxis to Reduce Late CMV After Lung Transplantation

BACKGROUND

We provide the results of the first interventional study of cytomegalovirus (CMV)-specific immune monitoring to direct the length of antiviral prophylaxis in lung transplantation (LTx).

METHODS

Patients (n = 118) at risk of CMV infection were randomized 1:2 to either 5 months or variable length valganciclovir prophylaxis (5-11 mo post-LTx), as determined by the QuantiFERON (QFN)-CMV assay. Patients with a negative QFN-CMV assay (< 0.2 IU/mL) received prolonged valganciclovir prophylaxis.

RESULTS

The primary endpoint that was the incidence of CMV infection in the lung allograft within 18 months of LTx was significantly reduced in the QFN-CMV directed arm (37% versus 58%, P = 0.03). Secondary endpoints that included blood viremia, acute rejection, and chronic lung allograft dysfunction did not differ between the 2 arms. Of the 80/118 patients who ceased antiviral prophylaxis at 5 months, the incidence of viremia (> 600 copies/mL) within the blood was significantly reduced in patients with a positive QFN-CMV assay compared with those without protective immunity (13% versus 67%, P = 0.0003), as was the incidence of severe viremia (> 10 000 copies/mL) (3% versus 50%, P < 0.001). Ceasing antiviral prophylaxis at 11 months in patients with a negative assay was associated with a 25% incidence of late CMV viremia.

CONCLUSIONS

Cytomegalovirus immune monitoring allows an individualized approach to CMV prophylaxis and reduces late CMV infection within the lung allograft.

NKG2C Natural Killer Cells in Bronchoalveolar Lavage Are Associated With Cytomegalovirus Viremia and Poor Outcomes in Lung Allograft Recipients

BACKGROUND

Cytomegalovirus (CMV) infection is a risk factor for chronic lung allograft dysfunction (CLAD), which limits survival in lung allograft recipients. Natural killer (NK) cells that express the NKG2C receptor mediate CMV-specific immune responses. We hypothesized that NKG2C NK cells responding to CMV in the lung allograft would reduce CMV-related inflammation and would improve CLAD-free survival.

METHODS

We prospectively followed 130 subjects who underwent lung transplantation from 2012 to 2016. Bronchoalveolar lavage (BAL) NK cells were immunophenotyped for NKG2C, maturation, and proliferation markers. CMV viral load, serologies, serial spirometry, and mortality were recorded from medical records. Natural killer cell subset association with CMV endpoints were made using generalized estimating equation-adjusted linear models. BAL NKG2C NK cell association with CLAD-free survival was assessed by Cox proportional hazards modeling.

RESULTS

NKG2C NK cells were more mature and proliferative than NKG2C NK cells and represented a median of 7.8% of BAL NK cells. The NKG2C NK cell proportion increased prior to the first detection of viremia and was nearly tripled in subjects with high level viremia (>1000 copies/mL) compared with no detected viremia. Subjects with increased BAL NKG2C NK cells, relative to the median, had a significantly increased risk for CLAD or death (hazard ratio, 4.2; 95% confidence interval, 1.2-13.3).

CONCLUSIONS

The BAL NKG2C NK cell proportion may be a relevant biomarker for assessing risk of CMV viremia and quantifying potential CMV-related graft injury that can lead to CLAD or death.

Indefinite cytomegalovirus prophylaxis with valganciclovir after lung transplantation

Human cytomegalovirus (HCMV) infections and reactivations are common after lung transplantation and are associated with the development of bronchiolitis obliterans syndrome. Against this background, temporary HCMV prophylaxis is an established standard regimen after lung transplantation in most centers. However, the optimal duration of prophylaxis is unclear. We conducted a retrospective two-center study to determine the efficacy of indefinite lifelong HCMV prophylaxis with oral valganciclovir in a cohort of 133 lung transplant recipients with a mean follow-up time of approximately 5 years. During the follow-up period, HCMV DNA was detected in 22 recipients (16.5%). In one case, HCMV pneumonitis developed after prophylaxis had been terminated. We observed a beneficial safety profile and tolerability in our cohort, as the majority of patients still received valganciclovir after a 1- and 3-year observation period, respectively. Compared to the literature, these data indicate a beneficial effect of extended valganciclovir prophylaxis with an acceptable safety profile.

First-Onset Herpesviral Infection and Lung Injury in Allogeneic Hematopoietic Cell Transplantation

Rationale: "Noninfectious" pulmonary complications are significant causes of morbidity and mortality after allogeneic hematopoietic cell transplant. Early-onset viral reactivations or infections are common after transplant. Whether the first-onset viral infection causes noninfectious pulmonary complications is unknown. Objectives: To determine whether the first-onset viral infection within 100 days after transplant predisposes to development of noninfectious pulmonary complications. Methods: We performed a retrospective review of 738 allogeneic hematopoietic cell transplant patients enrolled from 2005 to 2011. We also established a novel bone marrow transplantation mouse model to test whether herpesviral reactivation after transplant causes organ injury. Measurements and Main Results: First-onset viral infections with human herpesvirus 6 or Epstein-Barr virus within 100 days after transplant increase the risk of developing idiopathic pneumonia syndrome (adjusted hazard ratio [aHR], 5.52; 95% confidence interval [CI], 1.61-18.96; P = 0.007; and aHR, 9.21; 95% CI, 2.63-32.18; P = 0.001, respectively). First infection with human cytomegalovirus increases risk of bronchiolitis obliterans syndrome (aHR, 2.88; 95% CI, 1.50-5.55; P = 0.002) and grade II-IV acute graft-versus-host disease (aHR, 1.59; 95% CI, 1.06-2.39; P = 0.02). Murine roseolovirus, a homolog of human herpesvirus 6, can also be reactivated in the lung and other organs after bone marrow transplantation. Reactivation of murine roseolovirus induced an idiopathic pneumonia syndrome-like phenotype and aggravated acute graft-versus-host disease. Conclusions: First-onset herpesviral infection within 100 days after allogeneic hematopoietic cell transplant increases risk of pulmonary complications. Experimentally reactivating murine roseolovirus causes organ injury similar to phenotypes seen in human transplant recipients.

Myeloid-Derived Suppressor Cells in Lung Transplantation

Myeloid-derived suppressor cells (MDSC) are a heterogeneous group of immune cells from the myeloid lineage. MDSCs expand in pathological situations, such as chronic infection, cancer, autoimmunity, and allograft rejection. As chronic lung allograft dysfunction (CLAD) limits long-term survival after lung transplantation (LTx), MDSCs may play a role in its pathophysiology. We assessed phenotype and frequency of MDSCs in peripheral blood from lung transplant recipients and its relationship to post-transplant complications and immunosuppression. Granulocytic (G)-MDSC were identified and quantified by flow cytometry of blood from 4 control subjects and 20 lung transplant patients (stable n = 6, infection n = 5; CLAD n = 9). G-MDSC functionality was assessed in vitro by their capability to block CD4 and CD8 T cell proliferation. More G-MDSC could be assessed using EDTA tubes compared to heparin tubes (p = 0.004). G-MDSC were increased in stable lung transplant recipients vs. non-transplant controls (52.1% vs. 9.4%; p = 0.0095). The infection or CLAD groups had lower G-MDSCs vs. stable recipients (28.2%p = 0.041 and 33.0%; p = 0.088, respectively), but were not different among CLAD phenotypes. G-MDSC tended to correlate with cyclosporine A and tacrolimus levels (r² = 0.18; r² = 0.17). CD4 and CD8 cells proliferation decreased by 50 and 80% if co-cultured with MDSCs (1:6 and 1:2 MDSC:T-cell ratio, respectively). In conclusion, circulating MDSCs are measurable, functional and have a G-MDSC phenotype in lung transplant patients. Their frequency is increased in stable patients, decreased during post-transplant complications, and related to level of immunosuppression. This study may pave the way for further investigations of MDSC in the context of lung transplantation.

The Third International Consensus Guidelines on the Management of Cytomegalovirus in Solid-organ Transplantation

Despite recent advances, cytomegalovirus (CMV) infections remain one of the most common complications affecting solid organ transplant recipients, conveying higher risks of complications, graft loss, morbidity, and mortality. Research in the field and development of prior consensus guidelines supported by The Transplantation Society has allowed a more standardized approach to CMV management. An international multidisciplinary panel of experts was convened to expand and revise evidence and expert opinion-based consensus guidelines on CMV management including prevention, treatment, diagnostics, immunology, drug resistance, and pediatric issues. Highlights include advances in molecular and immunologic diagnostics, improved understanding of diagnostic thresholds, optimized methods of prevention, advances in the use of novel antiviral therapies and certain immunosuppressive agents, and more savvy approaches to treatment resistant/refractory disease. The following report summarizes the updated recommendations.