T-lymphocyte subsets in lung transplant recipients: association between nadir CD4 T-cell count and viral infections after transplantation

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.

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.

Acute rejection after liver transplantation is less common, but predicts better prognosis in HBV-related hepatocellular carcinoma patients

BACKGROUND

With a novel finding of significantly lower incidence of acute rejection (AR) in patients with hepatocellular carcinoma (HCC) after liver transplantation, compared with those with benign end-stage liver disease (BESLD), in a large national cohort, we analyzed the correlations among the perioperative immuno-inflammation status, postoperative AR, and prognosis in HCC and BESLD patients with same etiology of hepatitis B virus (HBV), who underwent liver transplantation.

METHODS

Patients who underwent liver transplantation due to HBV-related HCC or BESLD and experienced AR between September 2008 and April 2017 were analyzed retrospectively and followed up until April 2018. HCC patients with AR were matched with those without AR according to tumor stage and immunosuppressant concentration, at a 1:3 ratio. Preoperative immuno-inflammation status and prognosis of patients in both groups were compared.

RESULTS

The overall incidences of AR in patients with HCC and BESLD were 8.60% and 10.61%, respectively. The postoperative 28-day incidence of AR was significantly lower in HCC compared with BESLD patients (3.23% vs 7.08%, p = 0.031). Compared with BESLD patients, the rejection activity index and perioperative CD₄/CD₈ ratio were significantly lower (p = 0.047 and p < 0.001, respectively), while platelet/lymphocyte ratio was significantly higher in HCC patients (p = 0.041). Later tumor stage in HCC patients was associated with higher systemic immuno-inflammation index, neutrophil/lymphocyte ratio, monocyte/lymphocyte ratio, platelet/lymphocyte ratio, aspartate aminotransferase/lymphocyte ratio, C-reactive protein/albumin ratio and fibrinogen level, and lower CD₄/CD₈ ratio before transplantation. In HCC patients with AR, the percentage of regulatory T cells (CD₄⁺/CD₂₅⁺) and the level of IL-10 significantly decreased (p = 0.0023, < 0.0001, respectively), while Th1/Th2 ratio, levels of IFN-γ and IL-2 markedly increased before transplantation (p = 0.0018, 0.0059, 0.0416, respectively). Preoperative monocyte/lymphocyte ratio was an independent risk factor for overall and recurrence-free survival after liver transplantation in HCC patients (p = 0.025, < 0.001, respectively). The 1-, 3-, and 5-year survival rates were 76%, 71% and 53% in the AR group, and 67%, 37% and 25% in the non-AR group (p = 0.042).

CONCLUSION

Preoperative tumor-related immunosuppression may persist after liver transplantation in HCC patients, and reduce the incidence of AR. AR after liver transplantation may indicate a better prognosis in HCC patients.

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.

A simple score can identify kidney transplant recipients at high risk of severe infection over the following 2 years

BACKGROUND

The aim of this study was to determine whether a composite score of simple immune biomarkers and clinical characteristics could predict severe infections in kidney transplant recipients.

METHODS

We conducted a prospective study of 168 stable kidney transplant recipients who underwent measurement of lymphocyte subsets, immunoglobulins, and renal function at baseline and were followed up for 2 years for the development of any severe infections, defined as infection requiring hospitalization. A point score was developed to predict severe infection based on logistic regression analysis of factors in baseline testing.

RESULTS

Fifty-nine (35%) patients developed severe infection, 36 (21%) had two or more severe infections, and 3 (2%) died of infection. A group of 19 (11%) patients had the highest predicted infectious risk (>60%), as predicted by the score. Predictive variables were mycophenolate use, graft function, CD4+, and natural killer cell number. The level of immunosuppression score had an area under the receiver operating curve of 0.75 (95% CI: 0.67-0.83).

CONCLUSION

Our level of immunosuppression score for predicting the development of severe infection over 2 years has sufficient prognostic accuracy for identification of high-risk patients. This data can inform research that examines strategies to reduce the risks of infection.

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.

Sepsis is associated with lack of monocyte HLA-DR expression recovery without modulating T-cell reconstitution after lung transplantation

BACKGROUND

Immunosuppressive strategy targets mainly adaptive immunity after solid organ transplantation. We assessed the influence of early post-operative sepsis on T cell and monocyte reconstitution in anti-thymocyte globulin (ATG)-treated lung transplant recipients.

METHODS

We retrospectively included recipients who underwent a first lung transplant at our Lung Transplant Center (Marseille, France) between July 2011 and February 2013. Peripheral blood T-lymphocyte subset counts and monocyte HLA-DR (mHLA-DR) expression routinely performed by flow cytometry within 60 days post-transplant were analyzed. We compared the immune kinetics of patients who did or did not develop sepsis during the post-operative intensive care unit stay.

RESULTS

Among the 37 recipients included, 19 patients (51%) developed at least one episode of sepsis. At the ICU admission, septic recipients had higher SOFA score (9 [7.5-9] versus 6 [4-7]), p = .01), higher primary graft dysfunction score (1.4 ± 1.4 versus 0.3 ± 0.7, p = .008) and more frequent use of ECMO (47% versus 0%, p = .003). Whereas both groups had similar T-lymphocytes reconstitution in the post-operative period, mHLA-DR reconstitution was dramatically affected in septic patients after day 14, median mHLA-DR expression at 2.3 MFI [1.3-3.5] in the septic versus 8.0 MFI [5.1-10.5] in the non-septic group, p = .02.

CONCLUSION

We found that sepsis is negatively correlated with the mHLA-DR expression but not adaptive T cell immune reconstitution. This finding highlights the importance of immunomonitoring after lung transplantation and questions the strategy of a lower immunosuppression therapy in context of sepsis.

Effect of Immunosuppression on Target Blood Immune Cells Within 1 Year After Lung Transplantation: Influence of Age on T Lymphocytes

Background

Lymphocytes are targeted by immunosuppressive therapy in solid organ transplantation and they influence allograft outcome.

Material/Methods

Peripheral blood lymphocyte subsets (PBLS) determined by flow cytometry during the first year post-transplant from patients who underwent a first lung transplantation in a French University Hospital between December 2011 and July 2013 were retrospectively analyzed according to recipient characteristics and allograft outcome.

Results

Fifty-seven recipients were enrolled and 890 PBLS were collected. T lymphocytes and NK cells were rapidly decreased, below normal range, from the first postoperative days. B cells decreased more gradually, remaining within normal range, with the lowest level reached after day 100. In multivariate analysis, greater T lymphopenia was found in older recipients (−414 [−709 to −119] cells/μL, p=0.007). According to the outcome, multivariate analysis evidenced lower levels of lymphocytes when bacterial and viral infection occurred (−177 [−310 to −44] cells/μL, p=0.009 and (−601 [−984 to −218] cells/μL, p=0.002, respectively), higher CD8+ T lymphocytes with BOS (+324 [+94 to +553] cells/μL, p=0.006), and higher leukocytes with restrictive allograft syndrome (+3770 [+418 to +7122] cells/μL, p=0.028).

Conclusions

Aging is associated in our cohort with more severe T lymphopenia after induction therapy for lung transplantation. The analysis of leukocytes and PBLS is associated with specific profile according to the allograft outcome.

The role of CD4 cell count as discriminatory measure to guide chemoprophylaxis against Pneumocystis jirovecii pneumonia in human immunodeficiency virus-negative immunocompromised patients: A systematic review

BACKGROUND

In recent years, the incidence of Pneumocystis jirovecii pneumonia (PJP) has increased in immunocompromised patients without human immunodeficiency virus (HIV) infection. Chemoprophylaxis with trimethoprim-sulfamethoxazole (TMP-SMX) is highly effective in preventing PJP in both HIV-positive and -seronegative patients. In HIV-positive patients, the risk of PJP is strongly correlated with decreased CD4 cell count. The role of CD4 cell count in the pathogenesis of PJP in non-HIV immunocompromised patients is less well studied. For most immunosuppressive conditions, no clear guidelines indicate whether to start TMP-SMX.

METHOD

We conducted a systematic literature review with the aim to provide a comprehensive overview on the role of CD4 cell counts in managing the risk of PJP in HIV-seronegative patients.

RESULTS

Of the 63 individual studies retrieved, 14 studies report on CD4 cell counts in a variety of immunosuppressive conditions. CD4 cell count were <200/μL in 73.1% of the patients.

CONCLUSION

CD4 cell count <200/μL is a sensitive biomarker to identify non-HIV immunocompromised patients who are at risk for PJP. Measuring CD4 cell counts could help clinicians identify patients who may benefit from TMP-SMX prophylaxis.