Cytomegalovirus-associated allograft rejection in heart transplant patients

In Vitro Profiling of Commonly Used Post-transplant Immunosuppressants Reveals Distinct Impact on Antiviral T-cell Immunity Towards CMV

Infectious complications, including widespread human cytomegalovirus (CMV) disease, frequently occur after hematopoietic stem cell and solid organ transplantation due to immunosuppressive treatment causing impairment of T-cell immunity. Therefore, in-depth analysis of the impact of immunosuppressants on antiviral T cells is needed. We analyzed the impact of mTOR inhibitors sirolimus (SIR/S) and everolimus (EVR/E), calcineurin inhibitor tacrolimus (TAC/T), purine synthesis inhibitor mycophenolic acid (MPA/M), glucocorticoid prednisolone (PRE/P) and common double (T+S/E/M/P) and triple (T+S/E/M+P) combinations on antiviral T-cell functionality. T-cell activation and effector molecule production upon antigenic stimulation was impaired in presence of T+P and triple combinations. SIR, EVR and MPA exclusively inhibited T-cell proliferation, TAC inhibited activation and cytokine production and PRE inhibited various aspects of T-cell functionality including cytotoxicity. This was reflected in an in vitro infection model, where elimination of CMV-infected human fibroblasts by CMV-specific T cells was reduced in presence of PRE and all triple combinations. CMV-specific memory T cells were inhibited by TAC and PRE, which was also reflected with double (T+P) and triple combinations. EBV- and SARS-CoV-2-specific T cells were similarly affected. These results highlight the need to optimize immune monitoring to identify patients who may benefit from individually tailored immunosuppression.

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.

Patient years lost due to cytomegalovirus serostatus mismatching in the scientific registry of transplant recipients

Background

The cytomegalovirus (CMV) mismatch rate in deceased donor kidney transplant (DDKT) recipients in the US remains above 40%. Since CMV mismatching is common in DDKT recipients, the cumulative effects may be significant in the context of overall patient and graft survival. Our primary objective was to describe the short- and long-term risks associated with high-risk CMV donor positive/recipient negative (D+/R-) mismatching among DDKT recipients with the explicit goal of deriving a mathematical mismatching penalty.

Methods

We conducted a retrospective, secondary analysis of the Scientific Registry of Transplant Recipients (SRTR) database using donor-matched DDKT recipient pairs (N=105,608) transplanted between 2011-2022. All-cause mortality and graft failure hazard ratios were calculated from one year to ten years post-DDKT. All-cause graft failure included death events. Survival curves were calculated using the Kaplan-Meier estimation at 10 years post-DDKT and extrapolated to 20 years to provide the average graft days lost (aGDL) and average patient days lost (aPDL) due to CMV D+/R- serostatus mismatching. We also performed an age-based stratification analysis to compare the relative risk of CMV D+ mismatching by age.

Results

Among 31,518 CMV D+/R- recipients, at 1 year post-DDKT, the relative risk of death increased by 29% (p<0.001), and graft failure increased by 17% (p<0.001) as compared to matched CMV D+/R+ group (N=31,518). Age stratification demonstrated a significant increase in the risk associated with CMV mismatching in patients 40 years of age and greater. The aGDL per patient due to mismatching was 125 days and the aPDL per patient was 100 days.

Conclusion

The risks of CMV D+/R- mismatching are seen both at 1 year post-DDKT period and accumulated throughout the lifespan of the patient, with the average CMV D+/R- recipient losing more than three months of post-DDKT survival time. CMV D+/R- mismatching poses a more significant risk and a greater health burden than previously reported, thus obviating the need for better preventive strategies including CMV serodirected organ allocation to prolong lifespans and graft survival in high-risk patients.

Multicenter study of universal prophylaxis versus pre-emptive therapy for patients at intermediate risk (R+) for CMV following heart transplantation

INTRODUCTION

Heart transplant (HT) recipients with prior exposure to cytomegalovirus (CMV R+) are considered intermediate risk for CMV-related complications. Consensus guidelines allow for either universal prophylaxis (UP) or preemptive therapy (PET) (serial CMV testing) approaches to CMV prevention in such patients. Whether an optimal approach to mitigate CMV related risks exists in this setting remains uncertain. We therefore assessed the utility of PET as compared to UP in CMV R+ HT recipients.

METHODS

Retrospective analysis of all CMV R+ HT recipients from 6 U.S. centers between 2010 and 2018 was performed. The primary outcome was the development of CMV DNAemia or end-organ disease resulting in the initiation/escalation of anti-CMV therapy. The secondary outcome was CMV-related hospitalization. Additional outcomes included incidence of acute cellular rejection (ACR) ≥ grade 2R, death, cardiac allograft vasculopathy (CAV), and leukopenia.

RESULTS

Of 563 CMV R+ HT recipients, 344 (61.1%) received UP. PET was associated with increased risk for the primary (adjusted HR 3.95, 95% CI: 2.65-5.88, p < .001) and secondary (adjusted HR 3.19, 95% CI: 1.47-6.94, p = .004) outcomes, and with increased ACR ≥ grade 2R (PET 59.4% vs. UP 34.4%, p < .001). Incidence of detectable CAV was similar at 1 year (PET 8.2% vs. UP 9.5%, p = .698). UP was associated with increased incidence of leukopenia within 6 months post-HT (PET 34.7% vs. UP 43.6%, p = .036).

CONCLUSION

The use of a PET CMV prophylaxis strategy in intermediate risk HT recipients associated with increased risk of CMV infection and CMV-related hospitalization, and may associate with worse post-HT graft outcomes.

Primary Graft Dysfunction Is Associated With Development of Early Cardiac Allograft Vasculopathy, but Not Other Immune-mediated Complications, After Heart Transplantation

BACKGROUND

We investigated associations between primary graft dysfunction (PGD) and development of acute cellular rejection (ACR), de novo donor-specific antibodies (DSAs), and cardiac allograft vasculopathy (CAV) after heart transplantation (HT).

METHODS

A total of 381 consecutive adult HT patients from January 2015 to July 2020 at a single center were retrospectively analyzed. The primary outcome was incidence of treated ACR (International Society for Heart and Lung Transplantation grade 2R or 3R) and de novo DSA (mean fluorescence intensity >500) within 1 y post-HT. Secondary outcomes included median gene expression profiling score and donor-derived cell-free DNA level within 1 y and incidence of cardiac allograft vasculopathy (CAV) within 3 y post-HT.

RESULTS

When adjusted for death as a competing risk, the estimated cumulative incidence of ACR (PGD 0.13 versus no PGD 0.21; P  = 0.28), median gene expression profiling score (30 [interquartile range, 25-32] versus 30 [interquartile range, 25-33]; P  = 0.34), and median donor-derived cell-free DNA levels was similar in patients with and without PGD. After adjusting for death as a competing risk, estimated cumulative incidence of de novo DSA within 1 y post-HT in patients with PGD was similar to those without PGD (0.29 versus 0.26; P  = 0.10) with a similar DSA profile based on HLA loci. There was increased incidence of CAV in patients with PGD compared with patients without PGD (52.6% versus 24.8%; P  = 0.01) within the first 3 y post-HT.

CONCLUSIONS

During the first year after HT, patients with PGD had a similar incidence of ACR and development of de novo DSA, but a higher incidence of CAV when compared with patients without PGD.

Human cytomegalovirus and Epstein-Barr virus infections occurring early after transplantation are risk factors for antibody-mediated rejection in heart transplant recipients

Background

Antibody-mediated rejection (AMR) is a serious complication affecting the survival of patients receiving transplantation. Human cytomegalovirus (CMV) and Epstein-Barr virus (EBV) are common viral infections that occur after transplantation, frequently emerging as viral reactivation in donor grafts or transplant recipients. The present study aimed to investigate the association between CMV and EBV infections and early-onset AMR.

Materials and methods

This study was conducted at the Heart Transplantation Center of Padova General Hospital and included a cohort of 47 heart transplant recipients (HTxs), including 24 HTxs diagnosed with AMR and 23 control HTxs with no episodes of AMR. Only early cases of CMV and/or EBV infections (1-90 days after transplantation) were considered. Fisher's exact test and logistic regression analysis were used to statistically analyze the correlation and association between AMR and CMV or EBV infection.

Results

We observed a positive statistical association between CMV and EBV infections (two-sided Fisher's exact test, p = 0.0136) and between EBV infection and AMR (two-sided Fisher's exact test, p = 0.0034). Logistic regression analysis revealed a direct statistical association between CMV and EBV infections and AMR risk (p = 0.037 and 0.006 and odds ratio = 1.72 and 2.19, respectively). AMR occurrence was associated with increased viral loads of both CMV and EBV early after transplantation.

Discussion

These findings suggest the role of CMV and EBV infections as relevant risk factors for AMR in HTxs for the first time.

Absolute Lymphocyte Count as a Marker for Cytomegalovirus Infection After Heart Transplantation

BACKGROUND

Previous studies indicate an association between reduced absolute lymphocyte count (ALC) and cytomegalovirus (CMV) infection after solid organ transplantation and have therefore highlighted the potential of ALC as a simple tool to predict CMV infection in transplant patients. This study aimed to examine the utility of ALC as a valuable marker for CMV infection in heart transplant patients.

METHODS

Clinical information and ALC data of all adult patients who received orthotopic heart transplantation at the Medical University of Vienna between January 2004 and May 2019 were collected. We performed a multivariable Cox regression model that incorporates repeated measurements of ALC as a time-varying continuous factor in 2 ways, first as continuous logarithmic factor considering a 50% decrease of ALC levels and second as binary factor using a threshold of 610 cells/μL.

RESULTS

One hundred fifty-eight (39%) patients developed CMV infection over the course of 2 y. Patients with lymphopenia were shown to be at higher risk of developing CMV infection both in the continuous approach (HR [per 50% reduction] 1.29; confidence interval [CI], 1.09-1.53; P = 0.003) and the binary approach with a cutoff of 610 cells/μL (HR 1.74; CI, 1.20-2.51; P = 0.003).

CONCLUSIONS

This study demonstrated a strong association between reduced ALC and the development of CMV infection after heart transplantation. ALC value monitoring could provide an additional tool to assess individualized CMV risk after solid organ transplantation.

Impact of induction therapy on cytomegalovirus infection and post-transplant outcomes in pediatric heart transplant recipients receiving routine antiviral prophylaxis

OBJECTIVES

Induction therapy has been increasingly used in pediatric heart transplantation. This study evaluated the impact of anti-thymocyte globulin (ATG) versus basiliximab as induction therapy on post-transplant cytomegalovirus (CMV) infection, rejection at 1 year, coronary allograft vasculopathy (CAV), and mortality in pediatric heart transplant recipients receiving antiviral prophylaxis.

RESULTS

Of the 96 patients (age < 18 years) analyzed, 46 (47.9%) patients received basiliximab, and 50 (52.1%) received ATG. Median follow-up was 3.0 (IQR, 1.7-4.9) years with 32.3% reporting CMV infection. The ATG group, as compared with the basiliximab group, had similar incidences of CMV infection (36% vs. 28.3%, p = .418), CMV viremia (22% vs. 19.6%, p = .769), and CMV-positive tissue biopsy (30% vs. 22%, p = .486). The ATG group had lower incidences of rejection at 1 year (16% vs. 36.9%, p = .022) and CAV (4% vs. 23.9%, p = .006) with no difference in mortality (8% vs. 15.2%, p = .343), compared with the basiliximab group. Multivariate analysis showed that induction with ATG was associated with a lower risk of rejection at 1 year (OR, .31; 95% CI, .09-.94; p = .039) with no impact on the incidences of CMV infection (HR, 2.06; 95% CI, .54-7.89; p = .292), CAV (HR, .30; 95% CI, .04-2.58; p = .275), and mortality (HR, .39; 95% CI, .09-1.82; p = .233) compared to basiliximab induction.

DISCUSSION AND CONCLUSIONS

In conclusion, induction with ATG was associated with reduction in risk of rejection at 1 year with no effects on CMV infection, CAV, and mortality in pediatric heart transplant recipients with universal antiviral prophylaxis compared with basiliximab induction therapy.

Prevention and management of CMV infection in pediatric solid organ transplant recipients

Human cytomegalovirus (CMV) remains one of the most common opportunistic infections following solid organ transplantation in children. CMV causes morbidity and mortality through direct tissue-invasive disease and indirect immunomodulatory effects. In recent years, several new agents have emerged for the prevention and treatment of CMV disease in solid organ transplant recipients. However, pediatric data remain scarce, and many of the treatments are extrapolated from the adult literature. Controversies exist about the type and duration of prophylactic therapies and the optimal dosing of antiviral agents. This review provides an up-to-date overview of treatment modalities used to prevent and treat CMV disease in solid organ transplant (SOT) recipients.

Laboratory diagnostic testing for cytomegalovirus infection in solid organ transplant patients

Human cytomegalovirus (CMV) infection, which is one of the most common complications in transplant recipients, increases the risk of graft loss and rejection. Laboratory strategies for diagnosing CMV infection rely on the measurement of viral DNAemia and CMV-specific cell-mediated immunity (CMV-CMI). The CMV quantitative nucleic acid amplification test (QNAT) enabled the spread of preemptive therapy and prompted recommendations for surveillance, diagnosis, and monitoring. Despite the implementation of the World Health Organization international standard for calibration, variability of QNAT persists due to technical issues. CMV immunoglobulin G serology is the standard method for CMV immune screening of transplant candidates and donors. Assays for CMV-CMI play an important role in helping to predict the risk and to develop an individualized CMV management plan. Genotypic testing for resistance is needed when drug-resistant CMV infection is suspected. Here, we review the state of the art of laboratory tests for CMV infection in solid organ transplantation.

Patterns of Early Coronary Artery Changes in Pediatric Heart Transplant Recipients Detected Using Optical Coherence Tomography

BACKGROUND

Cardiac allograft vasculopathy, the leading cause of graft failure in pediatric heart transplant recipients, is characterized by diffuse and concentric coronary intimal thickening. Early treatment yields better outcomes. While coronary angiography is the standard for cardiac allograft vasculopathy screening and diagnosis, it only identifies luminal narrowing, which occurs in more severe disease. Coronary optical coherence tomography (OCT) is a high-definition intravascular imaging modality that may offer earlier diagnosis. We used OCT to investigate coronary intimal thickening in pediatric transplant recipients and examined its (1) location (ie, vessel type and location) and (2) nature (ie, characteristics of cross-sectional and longitudinal thickening).

METHODS

Sites collected coronary angiography and OCT data from participants (N=258 vessel segments from 73 individuals; median age: 11.5 years [8.4-15.3]; 55% male). Images were collected from the left anterior descending, left circumflex, and right coronary arteries, and location (ie, proximal, middle, and distal) were classified using coronary angiography.

RESULTS

OCT identified 32 vessel segments meeting criteria for significant thickening, 88% of which were angiographically silent. Longitudinal thickening was segmental rather than global in 88%, and cross-sectional thickening was 48% eccentric and 52% concentric. Intimal thickening prevalence and severity measures did not consistently differ between coronary artery type (P=1.000) or location (P=0.248) but increased with time since transplant and age at transplant and OCT procedure.

CONCLUSIONS

In pediatric transplant recipients, we observed a surprisingly high prevalence of segmental and eccentric intimal thickening. Insights from intravascular imaging suggest these patterns of coronary vascular changes may precede overt cardiac allograft vasculopathy. Identifying early changes may offer opportunity for enhanced surveillance and earlier intervention.

Observed elevated donor-derived cell free DNA in orthotopic heart transplant recipients without clinical evidence of rejection

Donor‐derived cell free DNA (dd‐cfDNA) has rapidly become part of rejection surveillance following orthotopic heart transplantation. However, some patients show elevated dd‐cfDNA without clinical evidence of rejection. With the aim to provide a clinical description of this subpopulation, we retrospectively analyzed 35 cardiac transplant recipients at our center who experienced elevated (≥.20%) dd‐cfDNA in the absence of clinical rejection, out of a total 106 recipients who had dd‐cfDNA results available during the first year. The median time to first elevated dd‐cfDNA level was 46 days, and the highest dd‐cfDNA recorded within 1 year was .31% [inter‐quartile range, .23–.45]. Twenty‐two (63%) patients experienced infections (cytomegalovirus (CMV) or other), and 16 (46%) presented with de novo donor‐specific antibodies. Cluster analysis revealed four distinct groups characterized by (a) subclinical rejection with 50% CMV (n = 16), (b) non‐CMV infections and the longest time to first elevated dd‐cfDNA (187 days) (n = 8), (c) right ventricular dysfunction (n = 6), and (d) women who showed the youngest median age (45 years) and highest median dd‐cfDNA (.50%) (n = 5). Continued prospective analysis is needed to determine if these observations warrant changes in patient management to optimize the utilization of this vital non‐invasive graft surveillance tool.

Diagnosis and management of cardiac allograft vasculopathy

One of the main causes of death beyond the first year after heart transplantation is cardiac allograft vasculopathy (CAV). This review summarises the current understanding of its complex pathophysiology, detection and treatment, including the available data on non-invasive imaging modalities used for screening and diagnosis. A better understanding of this entity is crucial to improving the long-term outcomes of the growing population of patients with a heart transplant.

Does reactivation of cytomegalovirus contribute to severe COVID-19 disease?

The majority of people infected with SARS-CoV-2 are asymptomatic or have mild to moderate symptoms. However, for unknown reasons, about 15 % have severe pneumonia requiring hospital care and oxygen support, and about 5 % develop acute respiratory distress syndrome, septic shock, and multiorgan failure that result in a high mortality rate. The risk of severe COVID-19 is highest among those who are over 70 years of age. Why severe COVID-19 develops in some people but not others is not understood. Could some cases involve reactivation of latent cytomegalovirus (CMV)?

COVID-19 management in heart transplanted recipients: registry of Almazov National Medical Research Centre

Aim      This study presents the experience of managing patients with COVID-19 after cardiac transplantation (CT).Material and methods  Infectious complications (IC) following CT are a leading cause for morbidity and mortality. A prolonged incubation period, atypical IC symptoms, and originally altered results of laboratory and instrumental diagnosis are characteristic of recipients due to immunosuppression. In 2020, the coronavirus infection (COVID-19) rapidly spread worldwide, and timely diagnosis and searching for effective treatments for this disease became a major challenge. From January 2010 through July 2020, 148 patients received orthotopic heart transplants at the V.A. Almazov National Medical Research Center; 34 of these patients died by the present time and were excluded from this analysis. 114 patients were included into the retrospective evaluation of results. These patients had been a part of the group followed up at the Center for more than a month.Results From March through July 2020, 12 (10.5 %) of 114 CT recipients were infected with the virus SARS-CoV-2. In 75 % (n=9) of the sick patients, the COVID-19 infection developed after more than one year after CT. From the first day of clinical symptoms, mycophenolic acid/everolimus were temporarily suspended. The outpatient treatment was started on the first day and included an antiviral therapy (oseltamivir), mucolytics (bromhexine), vitamin C, and anticoagulants. If the disease onset was associated with pyretic fever the empiric antibacterial levofloxacin treatment was administered due to a high risk of mixed infection. Hospitalized patients with moderately severe COVID-19 (n=3) were treated with oxygen inhalation through nasal cannula and prone position with a positive effect.Conclusion      Remote counseling of patients after CT and consistency of the outpatient treatment with recommendations of managing transplant physicians provided timely diagnosis of IC, early administration of treatment, and the absence of COVID-19 complications. Reducing the regimen of immunosuppressive therapy (antiproliferative agents) for up to 14 days facilitated infection control and was not associated with acute rejection crisis and/or impairment of the transplant function.

Association between cytomegalovirus infection and allograft rejection in a large contemporary cohort of heart transplant recipients

BACKGROUND

Cytomegalovirus (CMV) infection remains a common complication after heart transplantation (HTx). The association between CMV infection and allograft rejection is debated in the era of efficient prophylactic antiviral therapies.

METHODS

This single-center cohort study utilized a highly phenotyped database of HTx recipients (2012-2016). The primary endpoint was the analysis of the association between CMV infection (CMV load ≥ 500 IU/mL whole blood) and the risk of allograft rejection (cellular rejection ≥ 1R1B, antibody-mediated rejection ≥ pAMR1). Secondary endpoints included the analysis of a higher CMV load threshold (≥10 000 IU/mL) and different risk periods after PCR positivity. A mixed-effect logistic regression model with a random intercept was applied. Results were adjusted for important risk factors of rejection.

RESULTS

Overall, 384 patients were included and 6388 CMV loads and 3,494 endomyocardial biopsies were analyzed. CMV infections ≥ 500 IU/mL were diagnosed on 1223 (19.2%) blood samples from 284 (72.1%) patients and allograft rejections on 246 biopsies (7%) from 149 patients (38.8%). We did not find any association between CMV infection ≥ 500 IU/mL and rejection (univariable: OR 0.94, 95% CI [0.61, 1.45], P = .78, multivariable: OR 0.86, 95% CI [0.55, 1.33], P = .85). These results were consistent when analyzing a higher CMV load threshold and different periods of risk, reinforced by internal validation procedures and a posteriori calculation of the power (primary endpoint: power = 0.82, 95% CI [0.79-0.84]) and reproducible across different clinical scenarios.

CONCLUSIONS

CMV infection was not associated with an increased risk of rejection in a contemporary cohort of HTx recipients.

Impact of cytomegalovirus infection on gene expression profile in heart transplant recipients

BACKGROUND

Cytomegalovirus (CMV) infection has been implicated in the pathogenesis of allograft rejection in heart transplant (HT) recipients. The effect of a CMV infection on the gene expression profiling (GEP, AlloMap) scores in the absence of acute rejection is not known.

METHODS

Data from 14,985 samples collected from 2,288 adult HT recipients enrolled in Outcomes AlloMap Registry were analyzed. Patients with known CMV serology at the time of HT who had at least 1 AlloMap score reported during follow-up were included. AlloMap scores for those patients with CMV (but no ongoing rejection) were compared with those who were never infected. An exploratory analysis on the impact of CMV on available donor-derived cell-free DNA (AlloSure) was also performed.

RESULTS

A total of 218 patients (10%) were reported to have CMV infection after transplantation. AlloMap score in those samples with CMV infection (n = 311) had a GEP score (34; range: 29-36) significantly higher than the GEP score from samples (n = 14,674) obtained in the absence of CMV infection (30; range: 26-34; p < 0.0001). Both asymptomatic viremia and CMV disease demonstrated significantly higher AlloMap scores than no CMV infection samples (median scores: 33, 35, and 30, respectively; p < 0.0001). AlloSure levels, available for 776 samples, were not significantly different (median: 0.23% in 18 samples with CMV infection vs 0.15% in 776 samples without CMV infection; p = 0.66).

CONCLUSIONS

CMV infection in HT recipients is associated with an increase in AlloMap score, whereas AlloSure results do not appear to be impacted. This information should be considered when clinically interpreting abnormal/high AlloMap scores in HT recipients.

Cytomegalovirus infection and allograft rejection among pediatric heart transplant recipients in the era of valganciclovir prophylaxis

CMV infection remains a significant cause of morbidity among pediatric HTx recipients We explored the implications of CMV infection on post-transplant outcomes among CMV risk-stratified pediatric HTx recipients receiving VGC prophylaxis. Children who underwent HTx between January 2010 and October 2016 were stratified according to CMV risk at time of transplant and evaluated for evidence of post-transplant CMV infection, rejection, CAV, and graft loss. Among 97 children, 41 (42%) were considered HR or IR risk for CMV infection and received VGC prophylaxis. CMV DNAemia was observed in 34% of children, including 71% HR, 40% IR, and 18% LR individuals. Median time to CMV DNAemia following VGC prophylaxis was 32D among HR vs 277D in IR subjects (P = .042). No difference in overall graft loss was noted among groups, but CMV HR children had decreased rejection-free survival (3.5 years) compared to IR (6 years, P = .015) and LR children (8 years, P = .0003). CMV was noted on EMB in 13% of children but was not associated with increased CAV, rejection or graft loss. High-risk CMV status was associated with decreased time to CMV infection despite VGC prophylaxis, compared to IR, and decreased rejection-free survival times compared to both IR and LR recipients. Detection of CMV on EMB was not associated with increased rejection, CAV or graft loss. Additional studies are needed to explore the impact of CMV infection on rejection-free survival in HTx recipients.

Impact of late-onset cytomegalovirus infection in the development of cardiac allograft vasculopathy in heart transplant recipients

BACKGROUND

The impact of late-onset cytomegalovirus (CMV) infection (LOCI) on cardiac allograft vasculopathy (CAV) has yet to be established.

METHODS

A retrospective study was performed for patients who had undergone heart transplantation (HT) between January 1995 and October 2017 to analyze epidemiology of LOCI (any positive level of CMV pp65 antigenemia or DNAemia after 100 days, without previous CMV replication) and its association with CAV. Our main hypothesis was that LOCI causes less direct and indirect effects compared to early onset infection (EOCI).

RESULTS

Late-onset cytomegalovirus infection developed in 57 of 410 patients (13.9%) in a median time of 4.7 months post-transplant. CAV at 10 years was diagnosed in 31.6% of patients with LOCI, 34.6% with EOCI, and in 19.3% of CMV-uninfected patients. In the multivariate analysis, EOCI was an independent variable for developing CAV (HR 1.8, 95% CI 1.13-2.82, P = .01). Patients with LOCI showed a trend toward a higher risk of CAV, but the difference was not statistically significant (HR 1.7, 95% CI 0.95-3.08, P = .07). In the complementary log-log model, LOCI and EOCI had a similar CAV-free survival, and a higher probability of developing CAV than CMV-uninfected patients (P = .02).

CONCLUSIONS

Cytomegalovirus infection after HT may result in the same long-term events regardless of its onset, with a higher risk of developing CAV at 10 years than patients without CMV.

Cytomegalovirus myocarditis in solid organ transplant recipients: A case series and review of literature

Cytomegalovirus (CMV) is a DNA virus of the Herpesviridae family and is estimated to affect 15%-30% of high-risk solid organ transplant recipients. Typical manifestations of CMV end-organ disease in this population include colitis, esophagitis, and pneumonitis, and myocarditis is a rarely reported manifestation. We describe two cases of CMV myocarditis in solid organ transplant recipients and review the literature regarding previously published cases of CMV myocarditis.

Cytomegalovirus in solid organ transplant recipients-Guidelines of the American Society of Transplantation Infectious Diseases Community of Practice

Cytomegalovirus (CMV) is one of the most common opportunistic infections that affect the outcome of solid organ transplantation. This updated guideline from the American Society of Transplantation Infectious Diseases Community of Practice provides evidence-based and expert recommendations for screening, diagnosis, prevention, and treatment of CMV in solid organ transplant recipients. CMV serology to detect immunoglobulin G remains as the standard method for pretransplant screening of donors and transplant candidates. Antiviral prophylaxis and preemptive therapy are the mainstays of CMV prevention. The lack of a widely applicable viral load threshold for diagnosis and preemptive therapy is highlighted, as a result of variability of CMV nucleic acid testing, even in the contemporary era when calibrators are standardized. Valganciclovir and intravenous ganciclovir remain as drugs of choice for CMV management. Strategies for managing drug-resistant CMV infection are presented. There is an increasing use of CMV-specific cell-mediated immune assays to stratify the risk of CMV infection after solid organ transplantation, but their role in optimizing CMV prevention and treatment efforts has yet to be demonstrated. Specific issues related to pediatric transplant recipients are discussed.

Infections in Heart, Lung, and Heart-Lung Transplantation

Half a century has passed since the first orthotopic heart transplant took place. Surgical innovations allowed for heart, lung, and heart-lung transplantation to save lives of patients with incurable chronic cardiopulmonary conditions. The complexity of the surgical interventions, chronic host health conditions, and antirejection immunosuppressive medications makes infectious complications common. Infections have remained one of the main barriers for successful transplantation and a source of significant morbidity and mortality. Recognition of infections and its management in this setting require outstanding clinical skills since transplant recipients may not exhibit classic signs or symptoms of disease, and laboratory work has some pitfalls. The prevention, identification, and management of infectious diseases complications in this population are a priority to undertake to improve the medical outcomes of transplantation. Herein, we reviewed the historical aspects, epidemiology, and prophylaxis of infections in heart, lung, and heart-lung transplantation. We also discuss the most prevalent organisms affecting the host and the organ systems involved.

New therapies for human cytomegalovirus infections

The recent approval of letermovir marks a new era of therapy for human cytomegalovirus (HCMV) infections, particularly for the prevention of HCMV disease in hematopoietic stem cell transplant recipients. For almost 30 years ganciclovir has been the therapy of choice for these infections and by today's standards this drug exhibits only modest antiviral activity that is often insufficient to completely suppress viral replication, and drives the selection of drug-resistant variants that continue to replicate and contribute to disease. While ganciclovir remains the therapy of choice, additional drugs that inhibit novel molecular targets, such as letermovir, will be required as highly effective combination therapies are developed not only for the treatment of immunocompromised hosts, but also for congenitally infected infants. Sustained efforts, largely in the biotech industry and academia, have identified additional highly active lead compounds that have progressed into clinical studies with varying levels of success and at least two have the potential to be approved in the near future. Some of the new drugs in the pipeline inhibit new molecular targets, remain effective against isolates that have developed resistance to existing therapies, and promise to augment existing therapeutic regimens. Here, we will describe some of the unique features of HCMV biology and discuss their effect on therapeutic needs. Existing drugs will also be discussed and some of the more promising candidates will be reviewed with an emphasis on those progressing through clinical studies. The in vitro and in vivo antiviral activity, spectrum of antiviral activity, and mechanism of action of new compounds will be reviewed to provide an update on potential new therapies for HCMV infections that have progressed significantly in recent years.

Complications of Cardiac Transplantation

PURPOSE OF REVIEW

Despite the improvement in medical therapy for heart failure and the advancements in mechanical circulatory support, heart transplantation (HT) still remains the best therapeutic option to improve survival and quality of life in patients with advanced heart failure. Nevertheless, HT recipients are exposed to the risk of several potential complications that may impair their outcomes. In this article, we aim to provide a practical and scholarly framework for clinicians approaching heart transplant medicine, as well as a concise update for the experienced readers on the most relevant post-HT complications.

RECENT FINDINGS

While recognizing that most of the treatments herein discussed are based more on experience than on solid scientific evidence, significant step forward has been made in particular in the recognition and management of primary graft dysfunction, antibody-mediated rejection, and renal dysfunction. Complications after HT may vary according to the time from surgery and can be related to graft function and pathology or to diseases and dysfunctions occurring in other organs or systems, mainly as side effects of immunosuppressive drugs and progression of pre-existing conditions. Future research needs to focus on improving precision diagnostics of causes of graft dysfunction and on reaching an optimal and customized balance between efficacy and toxicities of immunosuppressive strategies.

Update on investigations pertaining to the pathogenesis of biliary atresia

Biliary atresia is a devastating biliary disease of neonates that results in liver transplantation for the vast majority. The etiology of biliary atresia is unknown and is likely multifactorial, with components of genetic predisposition, environmental trigger and autoimmunity contributing to disease pathogenesis. This review highlights recent work related to investigations of disease pathogenesis in biliary atresia.

Heart Transplantation and Risk of Cardiac Vasculopathy Development: What Factors Are Important?

BACKGROUND The aim of this study was to find the main risk factors for development of cardiac allograft vasculopathy (CAV), especially factors identified before the surgical procedure and factors related to the recipient profile and the medical history of the donor. MATERIAL AND METHODS There were 147 patients who had heart transplantation (HT) included in this study: mean age was 45.8±15.3 years. All study patients had coronary angiography after HT. Analyzed risk factors were: non-immunologic recipient risk factors (age of transplantation, smoking, hypertension, lipids, diabetes, obesity and weight gain after HT), immunologic recipient risk factors (acute cellular rejection (ACR), acute humoral rejection (AMR), cytomegalovirus (CMV) episodes), and donor-related risk factors (age, sex, catecholamine usage, ischemic time, compatibility of sex and blood groups, cause of death, cardiac arrest). RESULTS CAV was recognized in 48 patients (CAV group); mean age 53.6±13.6 years. There were 99 patients without CAV (nonCAV group); mean age 48.3±15.5 years. A univariate Cox analysis of the development of coronary disease showed statistical significance (p<0.05) for baseline high-density lipid (HDL), ACR, AMR, CMV, and donor age. Multivariate Cox regression model confirmed that only baseline HDL, episodes of ACR, donor age, and CMV infection are significant for the frequency of CAV after HT. CONCLUSIONS Older donor age is highly associated with CAV development. Older donor age and low level of HDL in heart recipients with the strongest influence of immunologic risk factors (ACR, CMV infection) were linked with development of CAV.

Infection in Organ Transplantation

The prevention, diagnosis, and management of infectious disease in transplantation are major contributors to improved outcomes in organ transplantation. The risk of serious infections in organ recipients is determined by interactions between the patient's epidemiological exposures and net state of immune suppression. In organ recipients, there is a significant incidence of drug toxicity and a propensity for drug interactions with immunosuppressive agents used to maintain graft function. Thus, every effort must be made to establish specific microbiologic diagnoses to optimize therapy. A timeline can be created to develop a differential diagnosis of infection in transplantation based on common patterns of infectious exposures, immunosuppressive management, and antimicrobial prophylaxis. Application of quantitative molecular microbial assays and advanced antimicrobial therapies have advanced care. Pathogen-specific immunity, genetic polymorphisms in immune responses, and dynamic interactions between the microbiome and the risk of infection are beginning to be explored. The role of infection in the stimulation of alloimmune responses awaits further definition. Major hurdles include the shifting worldwide epidemiology of infections, increasing antimicrobial resistance, suboptimal assays for the microbiologic screening of organ donors, and virus-associated malignancies. Transplant infectious disease remains a key to the clinical and scientific investigation of organ transplantation.

Human Cytomegalovirus Latency: Approaching the Gordian Knot

Herpesviruses have evolved exquisite virus-host interactions that co-opt or evade a number of host pathways to enable the viruses to persist. Persistence of human cytomegalovirus (CMV), the prototypical betaherpesvirus, is particularly complex in the host organism. Depending on host physiology and the cell types infected, CMV persistence comprises latent, chronic, and productive states that may occur concurrently. Viral latency is a central strategy by which herpesviruses ensure their lifelong persistence. Although much remains to be defined about the virus-host interactions important to CMV latency, it is clear that checkpoints composed of viral and cellular factors exist to either maintain a latent state or initiate productive replication in response to host cues. CMV offers a rich platform for defining the virus-host interactions and understanding the host biology important to viral latency. This review describes current understanding of the virus-host interactions that contribute to viral latency and reactivation.

Treatment and prevention of cytomegalovirus infection in heart and lung transplantation: an update

INTRODUCTION

Heart and lung transplantation are standard therapeutic strategies to improve survival and quality of life in selected patients with end-stage heart or lung diseases. Cytomegalovirus (CMV) is one the most clinically relevant and frequent post-transplant infectious agents, which may cause direct acute syndromes, and chronic indirect graft-related injury. Despite effective antiviral drugs being available to prevent and treat CMV infection, due to the immunosuppression burden and the specific characteristics of thoracic grafts, CMV infection remains a major clinical problem in heart and lung transplant recipients.

AREAS COVERED

We performed an extensive literature search focused on studies specifically including heart or lung transplantation, when available, or kidney transplant recipients when data on thoracic transplants were not available. We discuss the pros and cons supporting the use of currently available drugs and strategies for CMV prevention and treatment, highlighting current unmet needs.

EXPERT OPINION

While (Val)Ganciclovir remains the cornerstone of anti-CMV therapy, prolonged universal prophylaxis may expose a large number of patients to an excess of drug toxicity. Additional drugs with lower toxicity may be available in the context of anti-CMV prophylaxis, and effective CMV-risk stratification, by means of novel immune monitoring assays, which may help to customize the therapeutic approach.

Cytomegalovirus driven immunosenescence-An immune phenotype with or without clinical impact?

The continuous emerging increase in life span has led to vulnerability to a number of different diseases in the elderly. Some of these risks may be attributed to specific changes in the immune system referred to as immunoscenescence. This term aims to describe decreased immune functions among elderly individuals, and is characterized to be harmful age-associated changes in the immune system that lead to its gradual immune dysfunction. An impaired function of the immune system may increase susceptibility to various diseases in the elderly population such as infections, cardiovascular diseases and cancer. Although it is unclear how this immune phenotype develops, emerging evidence suggest that it may reflect an exhaustion of the immune system, possibly caused by one or several chronic infections. The main candidate is human cytomegalovirus (CMV), which can induce immune dysfunctions observed in immunoscenescence. Although the immune system is currently considered to be exhausted in CMV positive elderly individuals, it is not known whether such dysfunction of the immune system is a main reason for increased susceptibility to other diseases, or if direct effects of the virus in disease pathogenesis reflect the increased vulnerability to them. These aspects will be discussed in this review.

Risk factors of cardiac allograft vasculopathy

Despite advances in prevention and treatment of heart transplant rejection, development of cardiac allograft vasculopathy (CAV) remains the leading factor limiting long-term survival of the graft. Cardiac allograft vasculopathy etiopathogenesis is not fully understood, but a significant role is attributed to endothelial cell damage, caused by immunological and non-immunological mechanisms. Immunological factors include the differences between the recipient's and the donor's HLA systems, the presence of alloreactive antibodies and episodes of acute rejection. Among the non-immunological factors the most important are the age of the donor, ischemia-reperfusion injury and cytomegalovirus infection. The classical cardiovascular risk factors (diabetes, hypertension, obesity and hyperlipidemia) are also important. This study presents an up-to-date overview of current knowledge on the vasculopathy etiopathogenesis and the role played by endothelium and inflammatory processes in CAV, and it also investigates the factors which may serve as risk markers of cardiac allograft vasculopathy.

Cytomegalovirus infection and disease reduce 10-year cardiac allograft vasculopathy-free survival in heart transplant recipients

Background

Cytomegalovirus (CMV) is associated with an increased risk of cardiac allograft vasculopathy (CAV), the major limiting factor for long-term survival after heart transplantation (HTx). The purpose of this study was to evaluate the impact of CMV infection during long-term follow-up after HTx.

Methods

A retrospective, single-centre study analyzed 226 HTx recipients (mean age 45 ± 13 years, 78 % men) who underwent transplantation between January 1988 and December 2000. The incidence and risk factors for CMV infection during the first year after transplantation were studied. Risk factors for CAV were included in an analyses of CAV-free survival within 10 years post-transplant. The effect of CMV infection on the grade of CAV was analyzed.

Results

Survival to 10 years post-transplant was higher in patients with no CMV infection (69 %) compared with patients with CMV disease (55 %; p = 0.018) or asymptomatic CMV infection (54 %; p = 0.053). CAV-free survival time was higher in patients with no CMV infection (6.7 years; 95 % CI, 6.0–7.4) compared with CMV disease (4.2 years; CI, 3.2–5.2; p < 0.001) or asymptomatic CMV infection (5.4 years; CI, 4.3–6.4; p = 0.013). In univariate analysis, recipient age, donor age, coronary artery disease (CAD), asymptomatic CMV infection and CMV disease were significantly associated with CAV-free survival. In multivariate regression analysis, CMV disease, asymptomatic CMV infection, CAD and donor age remained independent predictors of CAV-free survival at 10 years post-transplant.

Conclusions

CAV-free survival was significantly reduced in patients with CMV disease and asymptomatic CMV infection compared to patients without CMV infection. These findings highlight the importance of close monitoring of CMV viral load and appropriate therapeutic strategies for preventing asymptomatic CMV infection.

HIV, highly active antiretroviral therapy and the heart: a cellular to epidemiological review

The advent of potent highly active antiretroviral therapy (HAART) for persons infected with HIV-1 has led to a "new" chronic disease with complications including cardiovascular disease (CVD). CVD is a significant cause of morbidity and mortality in persons with HIV infection. In addition to traditional risk factors such as smoking, hypertension, insulin resistance and dyslipidaemia, infection with HIV is an independent risk factor for CVD. This review summarizes: (1) the vascular and nonvascular cardiac manifestations of HIV infection; (2) cardiometabolic effects of HAART; (3) atherosclerotic cardiovascular disease (ASCVD) risk assessment, prevention and treatment in persons with HIV-1 infection.

Cytomegalovirus infection in renal transplantation: clinical aspects, management and the perspectives

Cytomegalovirus infection is one of most frequent infectious complications after renal transplantation, and can be classified as primo-infection, when the transmission occurs through the graft, or reactivation, when the recipient is cytomegalovirus seropositive. After transplantation, cytomegalovirus can appear as an infection, when the patient presents with evidence of viral replication without symptoms or disease, which has two clinical spectra: typical viral syndrome or invasive disease, which is a less common form. Their effects can be classified as direct, while the disease is developed, or indirect, with an increase of acute rejection and chronic allograft dysfunction risks. Diagnosis must be made based on viremia by one of the standardized methods: antigenemia or PCR, which is more sensitive. The risk factors related to infection after transplantation are the serologic matching (positive donor and negative recipient) and anti-lymphocyte antibody drugs. One of the strategies to reduce risk of disease should be chosen for patients at high risk: preemptive treatment or universal prophylaxis. Recent clinical research has described ganciclovir resistance as an emergent problem in management of cytomegalovirus infection. Two types of mutation that cause resistance were described: UL97 (most frequent) and UL54. Today, sophisticated methods of immunologic monitoring to detect specific T-cell clones against cytomegalovirus are used in clinical practice to improve the management of high-risk patients after renal transplantation.

Anti-CMV-IgG positivity of donors is beneficial for alloHSCT recipients with respect to the better short-term immunological recovery and high level of CD4+CD25high lymphocytes

Hematopoietic stem cell transplantation from anti-cytomegalovirus immunoglobulin G (anti-CMV-IgG) positive donors facilitated immunological recovery post-transplant, which may indicate that chronic CMV infection has an effect on the immune system. This can be seen in the recipients after reconstitution with donor lymphocytes. We evaluated the composition of lymphocytes at hematologic recovery in 99 patients with hematologic malignancies post hematopoietic stem cell transplantation (HSCT). Anti-CMV-IgG seropositivity of the donor was associated with higher proportions of CD4+ (227.963 ± 304.858 × 106 vs. 102.050 ± 17.247 × 106 cells/L, p = 0.009) and CD4+CD25high (3.456 ± 0.436 × 106 vs. 1.589 ± 0.218 × 106 cells/L, p = 0.003) lymphocytes in the blood at hematologic recovery. The latter parameter exerted a diverse influence on the risk of acute graft-versus-host disease (GvHD) if low (1.483 ± 0.360 × 106 vs. 3.778 ± 0.484 × 106 cells/L, p < 0.001) and de novo chronic GvHD (cGvHD) if high (3.778 ± 0.780 × 106 vs. 2.042 ± 0.261 × 106 cells/L, p = 0.041). Higher values of CD4+ lymphocytes in patients who received transplants from anti-CMV-IgG-positive donors translated into a reduced demand for IgG support (23/63 vs. 19/33, p = 0.048), and these patients also exhibited reduced susceptibility to cytomegalovirus (CMV), Epstein-Barr virus (EBV) and/or human herpes 6 virus (HHV6) infection/reactivation (12/50 vs. 21/47, p = 0.032). Finally, high levels (³0.4%) of CD4+CD25high lymphocytes were significantly associated with better post-transplant survival (56% vs. 38%, four-year survival, p = 0.040). Donors who experience CMV infection/reactivation provide the recipients with lymphocytes, which readily reinforce the recovery of the transplanted patients' immune system.

Cardiac allograft vasculopathy: a donor or recipient induced pathology?

Cardiac allograft vasculopathy (CAV) is one of the main causes of late-stage heart failure after heart transplantation. CAV is characterized by concentric luminal narrowing of the coronary arteries, but the exact pathogenesis of CAV is still not unraveled. Many researchers show evidence of an allogeneic immune response of the recipient, whereas others show contrasting results in which donor-derived cells induce an immune response against the graft. In addition, fibrosis of the neo-intima can be induced by recipient-derived circulating cells or donor-derived cells. In this review, both donor and recipient sides of the story are described to obtain better insight in the pathogenesis of CAV. Dual outcomes were found regarding the contribution of donor and recipient cells in the initiation of the immune response and the development of fibrosis during CAV. Future research could focus more on the potential synergistic interaction of donor and recipient cells leading to CAV.

Everolimus initiation and early calcineurin inhibitor withdrawal in heart transplant recipients: a randomized trial

In a randomized, open-label trial, everolimus was compared to cyclosporine in 115 de novo heart transplant recipients. Patients were assigned within 5 days posttransplant to low-exposure everolimus (3–6 ng/mL) with reduced-exposure cyclosporine (n = 56), or standard-exposure cyclosporine (n = 59), with both mycophenolate mofetil and corticosteroids. In the everolimus group, cyclosporine was withdrawn after 7–11 weeks and everolimus exposure increased (6–10 ng/mL). The primary efficacy end point, measured GFR at 12 months posttransplant, was significantly higher with everolimus versus cyclosporine (mean ± SD: 79.8 ± 17.7 mL/min/1.73 m2 vs. 61.5 ± 19.6 mL/min/1.73 m2; p < 0.001). Coronary intravascular ultrasound showed that the mean increase in maximal intimal thickness was smaller (0.03 mm [95% CI 0.01, 0.05 mm] vs. 0.08 mm [95% CI 0.05, 0.12 mm], p = 0.03), and the incidence of cardiac allograft vasculopathy (CAV) was lower (50.0% vs. 64.6%, p = 0.003), with everolimus versus cyclosporine at month 12. Biopsy-proven acute rejection after weeks 7–11 was more frequent with everolimus (p = 0.03). Left ventricular function was not inferior with everolimus versus cyclosporine. Cytomegalovirus infection was less common with everolimus (5.4% vs. 30.5%, p < 0.001); the incidence of bacterial infection was similar. In conclusion, everolimus-based immunosuppression with early elimination of cyclosporine markedly improved renal function after heart transplantation. Since postoperative safety was not jeopardized and development of CAV was attenuated, this strategy may benefit long-term outcome.

Interacting mechanisms in the pathogenesis of cardiac allograft vasculopathy

Cardiac allograft vasculopathy is the major cause of late graft loss in heart transplant recipients. Histological studies of characteristic end-stage lesions reveal arterial changes consisting of a diffuse, confluent, and concentric intimal expansion containing graft-derived cells expressing smooth muscle markers, extracellular matrix, penetrating microvessels, and a host mononuclear cell infiltrate concentrated subjacent to an intact graft-derived luminal endothelial cell lining with little evidence of acute injury. This intimal expansion combined with inadequate compensatory outward remodeling produces severe generalized stenosis extending throughout the epicardial and intramyocardial arterial tree that causes ischemic graft failure. Cardiac allograft vasculopathy lesions affect ≥50% of transplant recipients and are both progressive and refractory to treatment, resulting in ≈5% graft loss per year through the first 10 years after transplant. Lesions typically stop at the suture line, implicating alloimmunity as the primary driver, but pathogenesis may be multifactorial. Here, we will discuss 6 potential contributors to lesion formation (1) conventional risk factors of atherosclerosis; (2) pre- or peritransplant injuries; (3) infection; (4) innate immunity; (5) T-cell-mediated immunity; and (6) B-cell-mediated immunity through production of donor-specific antibody. Finally, we will consider how these various mechanisms may interact with each other.