Monitoring of intracellular adenosine triphosphate in CD4(+) T cells to predict the occurrence of cytomegalovirus disease in kidney transplant recipients

Utility of the Interferon-Gamma Enzyme-Linked Immunosorbent Spot Assay to Predict Risk of Cytomegalovirus Infection in Kidney Transplant Recipients

Non-specific interferon-gamma (IFN-γ) enzyme-linked immunosorbent (ELISpot) responses after solid organ transplant (SOT) and their relationship with cytomegalovirus (CMV) reactivation have hardly been investigated. Adult kidney transplant (KT) recipients underwent measurement of IFN-γ-producing T cells using the ELISpot assay before and 1 month after transplantation. Data for CMV infection episodes were collected. Risk factors for post-transplant CMV infection, based on IFN-γ responses, were analyzed using a Cox proportional hazards model. A total of 93 KT recipients were enrolled in the study and 84 evaluable participants remained at 1 month post KT. Thirty-three (39%) recipients developed subsequent CMV infection within 6 months post-transplant. At 1-month post-transplant, IFN-γ-producing T cells with <250 spot-forming units (SFUs)/2.5 × 105 peripheral blood mononuclear cells (PBMCs) were significantly associated with CMV infection (HR 3.1, 95% CI 1.4-7.1, p = 0.007). On multivariable analysis, posttransplant IFN-γ-producing T cells with <250 SFUs/2.5 × 105 PBMCs remained independently associated with CMV infection (HR 3.1, 95% CI 1.2-7.8, p = 0.019). Conclusions: KT recipients with low IFN-γ-producing T cells measured by the ELISpot assay are more likely to develop CMV infection after transplantation. Therefore, measurement of nonspecific cell-mediated immunity ELISpot responses could potentially stratify recipients at risk of CMV infection (Thai Clinical Trials Registry, TCTR20210216004).

Cytomegalovirus Cell-Mediated Immunity: Ready for Routine Use?

Utilizing assays that assess specific T-cell-mediated immunity against cytomegalovirus (CMV) holds the potential to enhance personalized strategies aimed at preventing and treating CMV in organ transplantation. This includes improved risk stratification during transplantation compared to relying solely on CMV serostatus, as well as determining the optimal duration of antiviral prophylaxis, deciding on antiviral therapy when asymptomatic replication occurs, and estimating the risk of recurrence. In this review, we initially provide an overlook of the current concepts into the immune control of CMV after transplantation. We then summarize the existent literature on the clinical experience of the use of immune monitoring in organ transplantation, with a particular interest on the outcomes of interventional trials. Current evidence indicates that cell-mediated immune assays are helpful in identifying patients at low risk for replication for whom preventive measures against CMV can be safely withheld. As more data accumulates from these and other clinical scenarios, it is foreseeable that these assays will likely become part of the routine clinical practice in organ transplantation.

A Systematic Review and Meta-analysis of Optimized CMV Preemptive Therapy and Antiviral Prophylaxis for CMV Disease Prevention in CMV High-Risk (D+R-) Kidney Transplant Recipients

The optimal strategy for cytomegalovirus (CMV) disease prevention in CMV donor/recipient kidney transplant recipients remains uncertain. Conclusions of prior meta-analyses that CMV disease rates with preemptive therapy (PET) and universal prophylaxis (UP) were comparable may have been affected by inclusion of studies lacking key determinants of efficacy of the respective strategies.

Methods

We conducted a systematic review and meta-analysis of PET with weekly CMV polymerase chain reaction monitoring for ≥3 mo and UP with 6 mo of valganciclovir. PubMed and Embase databases were reviewed from January 1, 2010, to April 1, 2022. Risk of bias was assessed with 3 instruments (Cochrane RoB, Cochrane RoBINS-I, and an instrument for assessing risk in observational studies). The primary outcome was CMV disease incidence by 1-y posttransplant. Secondary outcomes by 1-y were graft loss, acute allograft rejection, and mortality. Results were synthesized using generalized linear mixed model meta-analysis. PET studies were stratified into low-threshold (LT) and high-threshold (HT) PET based on the viral load threshold for initiation of antiviral therapy.

Results

Twenty-five studies met inclusion criteria (6 PET, 19 UP). CMV disease incidence was significantly higher in HT (0.30 [95% confidence interval (CI), 0.22-0.39]) versus LT PET (0.06 [95% CI, 0.03-0.12]). LT PET was associated with a significantly lower CMV disease incidence (0.06 [95% CI, 0.03-0.12]) versus UP (0.21 [95% CI, 0.17-0.27]). Incidence of graft loss, acute allograft rejection, or mortality was not significantly different between LT PET and UP (P > 0.05 for all comparisons). Receipt of lymphocyte-depleting antibodies was not associated with a significant difference in CMV disease incidence (odds ratio = 1.34 [95% CI, 0.80-2.25]).

Conclusions

LT PET is associated with a significantly lower incidence of CMV disease compared to UP with similar rates of other clinical outcomes. These findings provide rationale and preliminary data for a randomized superiority trial of optimized LT-PET versus UP in donor seropositive recipient seronegative kidney transplant recipients.

Bacterial and Viral Infection and Sepsis in Kidney Transplanted Patients

Kidney transplanted patients are a unique population with intrinsic susceptibility to viral and bacterial infections, mainly (but not exclusively) due to continuous immunosuppression. In this setting, infectious episodes remain among the most important causes of death, with different risks according to the degree of immunosuppression, time after transplantation, type of infection, and patient conditions. Prevention, early diagnosis, and appropriate therapy are the goals of infective management, taking into account that some specific characteristics of transplanted patients may cause a delay (the absence of fever or inflammatory symptoms, the negativity of serological tests commonly adopted for the general population, or the atypical anatomical presentation depending on the surgical site and graft implantation). This review considers the recent available findings of the most common viral and bacterial infection in kidney transplanted patients and explores risk factors and outcomes in septic evolution.

Epidemiology, risk factors, and outcomes associated with cytomegalovirus in adult kidney transplant recipients: A systematic literature review of real-world evidence

Kidney transplant recipients (KTRs) have increased risk for cytomegalovirus (CMV) infection/disease given the necessity of drug-induced immunosuppression. A comprehensive review of published literature reporting real-world data on prevention strategies utilized and associated CMV burden outcomes is limited. Such data could help inform future clinical practice and identify unmet needs in CMV management. We conducted a systematic review of observational studies published in Medline or EMBASE from January 2008 to November 2018 to identify current real-world CMV management approaches, CMV infection/disease risk factors, and outcomes associated with CMV infection. Descriptive statistics and pooled quantitative analyses were conducted. From 1608 records screened, 86 citations, including 69 803 adult KTR, were included. Prophylaxis and preemptive therapy (PET) were predominant approaches among D+/R- and R + CMV serostatus transplants, respectively. Valganciclovir and ganciclovir were frequently utilized across CMV risk strata. Despite prevention approaches, approximately one-fourth of KTR developed CMV infection. Age and D+/R- CMV serostatus were consistent risk factors for CMV infection/disease. CMV infection/disease was associated with increased mortality and graft loss. CMV was similarly associated with acute rejection (AR) risk, but with high heterogeneity among studies. Limited data were available on CMV and opportunistic infections (OIs) risk. CMV remains a significant issue. New strategies may be needed to optimize CMV management.

Immunosuppressive Agents and Infectious Risk in Transplantation: Managing the "Net State of Immunosuppression"

Successful solid organ transplantation reflects meticulous attention to the details of immunosuppression, balancing risks for graft rejection against risks for infection. The 'net state of immune suppression' is a conceptual framework of all factors contributing to infectious risk. Assays which measure immune function in the immunosuppressed transplant recipient relative to infectious risk and allograft function are lacking. The best measures of integrated immune function may be quantitative viral loads to assess the individual's ability to control latent viral infections. Few studies address adjustment of immunosuppression during active infections. Thus, confronted with infection in solid organ recipients, the management of immunosuppression is based largely on clinical experience. This review examines known measures of immune function and the immunologic effects of common immunosuppressive drugs and available studies reporting modification of drug regimens for specific infections. These data provide a conceptual framework for the management of immunosuppression during infection in organ recipients.

Predictive tools to determine risk of infection in kidney transplant recipients

Introduction: Infection represents a major complication after kidney transplantation (KT). Therapeutic drug monitoring is essentially the only approach for the adjustment of immunosuppression in current practice, with suboptimal results. The implementation of immune monitoring strategies may contribute to minimizing the risk of adverse events attributable to over-immunosuppression without compromising graft outcomes.Areas covered: The present review (based on PubMed/MEDLINE searches from database inception to November 2019) is focused on immune biomarkers with no antigen specificity (non-pathogen-specific), including serum levels of immunoglobulins and complement factors, peripheral blood lymphocyte subpopulations, soluble CD30, intracellular ATP production by stimulated CD4⁺ T-cells, and other cell-based immune assays. We also summarized recent advances in the use of replication kinetics of latent viruses to assess the functionality of T-cell immunity, with focus on the nonpathogenic anelloviruses. Finally, the composite risk scores reported in the literature are critically discussed.Expert opinion: Notable efforts have been made to develop an enlarging repertoire of immune biomarkers and prediction models, although most of them still lack technical standardization and external validation. Preventive interventions based on these tools (prolongation of prophylaxis, tapering of immunosuppression, or immunoglobulin replacement therapy in hypogammaglobulinemic patients) remain to be defined, ideally in the context of controlled trials.

Immune function as predictor of infectious complications and clinical outcome in patients undergoing solid organ transplantation (the ImmuneMo:SOT study): a prospective non-interventional observational trial

Background

Solid organ transplantation (SOT) is a well-established and life-saving treatment for patients with end-stage organ failure. Organ rejection and infections are among the main complications to SOT and largely determines the clinical outcome. The correct level of immunosuppression is of major importance to prevent these complications. However, it is a consistent observation that in recipients on the same immunosuppressive regimens the clinical outcome varies, and no reliable marker exists to monitor immune function.

Methods

In a prospective, observational study, we plan to enroll 630 adult patients with a planned organ transplantation at Rigshospitalet, University of Copenhagen, Denmark. Prior to and on different time points up to two years after transplantation we will perform a complete immunological profile on the recipients. This profile will consist of classical descriptive immune phenotyping (flow cytometry and circulating biomarkers) and the functional assay TruCulture®. In TruCulture® whole blood is incubated ex vivo with stimulants imitating bacterial, viral and fungal infections, where after a panel of selected cytokines is quantified. Clinical data from electronic health records will be obtained from the PERSIMUNE (Centre of Excellence for Personalized Medicine of Infections Complications in Immune Deficiency at Rigshospitalet, Copenhagen) data repository, a warehouse of data generated as part of routine care including vital signs, biochemistry, microbiology, pathology as well as medication, demographics, diagnoses, hospital contacts, surgical procedures and mortality.

Discussion

This will be the first large scale study to determine several aspects of immune function and perform a complete immunological profiling in SOT recipients. It is expected that knowledge generated will provide information to generate prediction models identifying patients at increased risk of infection and/or rejection. If the study is successful, we will subsequently use the generated prediction models to propose personalized immunosuppressive regimens to be tested in future randomized controlled trials.

Trial registration

This study has been approved by the Regional ethical committee (H-17024315), the Danish Data Protection Agency (RH-2016-47, RH-2015-04, I-Suite 03605) and the Danish National board of Health (3–3013-1060/1). The trial is retrospectively registered at clinicaltrials.gov (NCT03847285) the 20th February 2019.

Can immune biomarkers predict infections in solid organ transplant recipients? A review of current evidence

Despite improvements in graft survival, solid organ transplantation is still associated with considerable infection induced morbidity and mortality. If we were able to show that serious infection risk was associated with excessive suppression of immune capacity, we would be justified in "personalizing" the extent of immunosuppression by carefully monitored reduction to see if we can improve immune compromize without increasing the risk of rejection. Reliable biomarkers are needed to identify this patients at an increased risk of infection. This review focuses on the currently available evidence in solid organ transplant recipients for immune non-pathogen specific biomarkers to predict severe infections with the susceptibility to particular pathogens according to the component of the immune system that is suppressed. This review is categorized into immune biomarkers representative of the humoral, cellular, phagocytic, natural killer cell and complement system. Biomarkers humoral and cellular systems of the that have demonstrated an association with infections include immunoglobulins, lymphocyte number, lymphocyte subsets, intracellular concentrations of adenosine triphosphate in stimulated CD4⁺ cells and soluble CD30. Biomarkers of the innate immune system that have demonstrated an association with infections include natural killer cell numbers, complement and mannose binding lectin. Emerging evidence shows that quantification of viral nucleic acid (such as Epstein Barr Virus) can act as a biomarker to predict all-cause infections. Studies that show the most promise are those in which several immune biomarkers are assessed in combination. Ongoing research is required to validate non-pathogen specific immune biomarkers in multi-centre studies using standardized study designs.