Prolonged CD4 T cell lymphopenia increases morbidity and mortality after renal transplantation

Biomarkers of biological aging in recipients of solid organ transplantation and clinical outcomes: A scoping review

INTRODUCTION

Biological aging is the accumulation of cellular and molecular damage within an individual over time. The biological age of a donor organ is known to influence clinical outcomes of solid organ transplantation, including delayed graft function and frequency of rejection episodes. While much research has focused on the biological age of donor organs, the recipient's biological age may also influence transplantation outcomes. The aim of this scoping review was to identify and provide an overview of the existing evidence regarding biological aging in solid organ transplant recipients and the impact on patient outcomes post-transplant.

METHODS

Literature searches were carried out on PubMed, Web of Science, Google Scholar, Embase and TRIP using the phrases 'solid organ transplant', 'cell senescence', 'cell aging' and 'outcomes', using boolean 'and/or' phrases and MeSH terms. Duplicates were removed and abstracts were reviewed by two independent reviewers. Full papers were then screened for inclusion by two reviewers. Data extraction was carried out using a standardised proforma agreed on prior to starting.

RESULTS

32 studies, including data on a total of 7760 patients, were identified for inclusion in this review; 23 relating to kidney transplant recipients, three to liver transplant, five to lung transplant and one to heart transplantation. A wide range of biomarkers of biological aging have been assessed in kidney transplant recipients, whereas studies of liver, lung and heart transplant have predominantly assessed recipient telomere length. The most robust associations with clinical outcomes are observed in kidney transplant recipients, possibly influenced by the larger number of studies and the use of a wider range of biomarkers of biological aging. In kidney transplant recipients reduced thymic function and accumulation of terminally differentiated T cell populations was associated with reduced risk of acute rejection but increased risk of infection and mortality.

CONCLUSION

Studies to date on biological aging in transplant recipients have been heavily biased to kidney transplant recipients. The results from these studies suggest recipient biological age can influence clinical outcomes and future research is needed to prioritise robust biomarkers of biological aging in transplant recipients.

Role of mTOR inhibitor in the cellular and humoral immune response to a booster dose of SARS-CoV-2 mRNA-1273 vaccine in kidney transplant recipients

Background

Immunocompromised patients have an increased risk of developing severe COVID disease, as well as a tendency to suboptimal responses to vaccines. The objective of this study was to evaluate the specific cellular and humoral adaptive immune responses of a cohort of kidney transplant recipients (KTR) after 3 doses of mRNA-1273 vaccine and to determinate the main factors involved.

Methods

Prospective observational study in 221 KTR (149 non infected), 55 healthy volunteers (HV) and 23 dialysis patients (DP). We evaluated anti-spike (by quantitative chemiluminescence immunoassay) and anti-nucleocapsid IgG (ELISA), percentage of TCD4⁺ and TCD8⁺ lymphocytes producing IFNγ against S-protein by intracellular flow cytometry after Spike-specific 15-mer peptide stimulation and serum neutralizing activity (competitive ELISA) at baseline and after vaccination.

Results

Among COVID-19 naïve KTR, 54.2% developed cellular and humoral response after the third dose (vs 100% in DP and 91.7% in HV), 18% only showed cell-mediated response, 22.2% exclusively antibody response and 5.6% none. A correlation of neutralizing activity with both the IgG titer (r=0.485, p<0.001) and the percentage of S-protein-specific IFNγ-producing CD8-T cells (r=0.198, p=0.049) was observed. Factors related to the humoral response in naïve KTR were: lymphocytes count pre-vaccination >1000/mm³ [4.68 (1.72-12.73, p=0.003], eGFR>30 mL/min [7.34(2.72-19.84), p<0.001], mTOR inhibitors [6.40 (1.37-29.86), p=0.018]. Infected KTR developed a stronger serologic response than naïve patients (96.8 vs 75.2%, p<0.001).

Conclusions

KTR presented poor cellular and humoral immune responses following vaccination with mRNA-1273. The immunosuppression degree and kidney function of these patients play an important role, but the only modifiable factor with a high impact on humoral immunogenicity after a booster dose was an immunosuppressive therapy including a mTOR inhibitor. Clinical trials are required to confirm these results.

Human papillomavirus in the setting of immunodeficiency: Pathogenesis and the emergence of next-generation therapies to reduce the high associated cancer risk

Human papillomavirus (HPV), a common sexually transmitted virus infecting mucosal or cutaneous stratified epithelia, is implicated in the rising of associated cancers worldwide. While HPV infection can be cleared by an adequate immune response, immunocompromised individuals can develop persistent, treatment-refractory, and progressive disease. Primary immunodeficiencies (PIDs) associated with HPV-related disease include inborn errors of GATA, EVER1/2, and CXCR4 mutations, resulting in defective cellular function. People living with secondary immunodeficiency (e.g. solid-organ transplants recipients of immunosuppression) and acquired immunodeficiency (e.g. concurrent human immunodeficiency virus (HIV) infection) are also at significant risk of HPV-related disease. Immunocompromised people are highly susceptible to the development of cutaneous and mucosal warts, and cervical, anogenital and oropharyngeal carcinomas. The specific mechanisms underlying high-risk HPV-driven cancer development in immunocompromised hosts are not well understood. Current treatments for HPV-related cancers include surgery with adjuvant chemotherapy and/or radiotherapy, with clinical trials underway to investigate the use of anti-PD-1 therapy. In the setting of HIV co-infection, persistent high-grade anal intraepithelial neoplasia can occur despite suppressive antiretroviral therapy, resulting in an ongoing risk for transformation to overt malignancy. Although therapeutic vaccines against HPV are under development, the efficacy of these in the setting of PID, secondary- or acquired- immunodeficiencies remains unclear. RNA-based therapeutic targeting of the HPV genome or mRNA transcript has become a promising next-generation therapeutic avenue. In this review, we summarise the current understanding of HPV pathogenesis, immune evasion, and malignant transformation, with a focus on key PIDs, secondary immunodeficiencies, and HIV infection. Current management and vaccine regimes are outlined in relation to HPV-driven cancer, and specifically, the need for more effective therapeutic strategies for immunocompromised hosts. The recent advances in RNA-based gene targeting including CRISPR and short interfering RNA (siRNA), and the potential application to HPV infection are of great interest. An increased understanding of both the dysregulated immune responses in immunocompromised hosts and of viral persistence is essential for the design of next-generation therapies to eliminate HPV persistence and cancer development in the most at-risk populations.

Anti‐thymocyte globulin‐mediated immunosenescent alterations of T cells in kidney transplant patients

Objectives

Kidney transplant (KT) is the most effective treatment for end‐stage renal disease. The immunosuppressant anti‐thymocyte globulin (ATG) has been applied for induction therapy to reduce the risk of acute transplant rejection for patients at high immunological risk. Despite its putative role in replicative stress during immune reconstitution, the effects of ATG on T‐cell immunosenescent changes remain to be understood.

Methods

Phenotypic and functional features of senescent T cells were examined by flow cytometry in 116 healthy controls (HC) and 95 KT patients for comparative analysis according to ATG treatment and CMV reactivation. The TCR repertoire was analysed in peripheral blood mononuclear cells (PBMCs) of KT patients.

Results

T cells of KT patients treated with ATG (ATG⁺) show typical immunosenescent features, accumulation of CD28⁻, CD85j⁺ or CD57⁺ T cells, and imbalance of functional T‐cell subsets, compared with untreated KT patients (ATG⁻). Plasma IL‐15 and CMV‐IgG levels were higher in KT patients than in HCs, and the IL‐15 level positively correlated with the frequency of CD28⁻ T cells in KT patients. ATG⁺ patients had a higher prevalence of CMV reactivation, which is associated with an increased frequency of CD28⁻ T cells. As a result, ATG⁺ patients had expanded CMV‐specific T cells and decreased TCR diversity. However, proliferation, cytokine‐producing capacity and polyfunctionality of T cells were preserved in ATG⁺ patients.

Conclusion

Our findings suggest that ATG treatment contributes to the accumulation of senescent T cells, which may have lifelong clinical implications in KT patients. Thus, these patients require long‐term and comprehensive immune monitoring.

Durability of Antibody Response after Primary Pneumococcal Double-Dose Prime-Boost Vaccination in Adult Kidney Transplant Recipients and Candidates: 18-Month Follow-Up in a Non-Blinded, Randomised Clinical Trial

Background: Pneumococcal prime-boost vaccination is recommended for solid organ transplant recipients and candidates. The long-term durability of the antibody (AB) response is unknown. The same applies to a dose-dependent immune response. Methods: We studied the durability of the vaccine response after 18 months in kidney transplant recipients (KTRs) and patients on the kidney transplant waiting list (WLPs). Both groups received either a normal dose (ND) or a double dose (DD) of the 13-valent pneumococcal conjugate vaccine and the 23-valent pneumococcal polysaccharide vaccine. The average pneumococcal AB geometric mean concentration (GMC) was evaluated. A level ≥ 1 mg/L was considered protective against invasive pneumococcal disease (IPD). Results: Sixty WLPs and 70 KTRs were included. The proportion of participants protected declined from 52% to 33% in WLPs and from 29% to 16% in KTRs, with the previously significant dose-effect in WLPs no longer present (40% DD vs. 27% ND; p = 0.273). Average pneumococcal AB GMCs remained significantly above baseline levels (all groups p ≤ 0.001). Drug-induced immunosuppression diminished the vaccine dose-effect. Conclusions: At follow-up, the pneumococcal prime-boost vaccination still provided significantly elevated average pneumococcal AB GMCs in both populations. Though the proportion of participants protected against IPD in WLP-DD and WLP-ND were statistically comparable, a DD may still be recommended for WLPs (EudraCT: 2016-004123-23).

Induction Therapy and Therapeutic Antibodies

Prevention of allograft rejection is one of the crucial goals in solid organ transplantation to ensure durability of the graft and is chiefly mediated by cellular and humoral pathways targeting cell surface alloantigens. The risk of rejection is highest in the first post-transplant year and wanes with time albeit the risk always exists and varies with the type of organ transplanted. Induction therapies refer to the use of high-intensity immunosuppression in the immediate post-operative period to mitigate the highest risk of rejection. This term encompasses chiefly the use of antibody therapies directed against one of the key pathways in T-cell activation or abrogating effects of circulating alloantibodies. These antibodies carry more potent immunomodulatory effect than maintenance immunosuppressive therapy alone and many of them lead to durable immune cell depletion. A variety of monoclonal and polyclonal antibodies have been utilized for use not only for induction therapy, but also for treatment of allograft rejection when it occurs and as components of desensitization therapy before and after transplantation to modulate circulating alloantibodies.

Effect of Kidney Transplantation on Accelerated Immunosenescence and Vascular Changes Induced by Chronic Kidney Disease

Kidney transplantation is the best option for patients with end-stage renal disease. Despite the improvement in cardiovascular burden (leading cause of mortality among patients with chronic kidney disease), cardiovascular adverse outcomes related to the inflammatory process remain a problem. Thus, the aim of the present study was to characterize the immune profile and microvesicles of patients who underwent transplantation. We investigated the lymphocyte phenotype (CD3, CD4, CD8, CD19, and CD56) and monocyte phenotype (CD14, CD16, CD86, and CD54) in peripheral blood, and endothelium-derived microvesicles (annexin V+CD31+CD41–) in plasma of patients with advanced chronic kidney disease (n = 40), patients with transplantation (n = 40), and healthy subjects (n = 18) recruited from the University Hospital “12 de Octubre” (Madrid, Spain). Patients with kidney transplantation had B-cell lymphopenia, an impairment in co-stimulatory (CD86) and adhesion (CD54) molecules in monocytes, and a reduction in endothelium-derived microvesicles in plasma. The correlations between those parameters explained the modifications in the expression of co-stimulatory and adhesion molecules in monocytes caused by changes in lymphocyte populations, as well as the increase in the levels of endothelial-derived microvesicles in plasma caused by changes in lymphocyte and monocytes populations. Immunosuppressive treatment could directly or indirectly induce those changes. Nevertheless, the particular characteristics of these cells may partly explain the persistence of cardiovascular and renal alterations in patients who underwent transplantation, along with the decrease in arteriosclerotic events compared with advanced chronic kidney disease. In conclusion, the expression of adhesion molecules by monocytes and endothelial-derived microvesicles is related to lymphocyte alterations in patients with kidney transplantation.

Unraveling the thread of uncontrolled immune response in COVID-19 and STEMI: an emerging need for knowledge sharing

The outbreak of severe acute respiratory syndrome coronavirus 2 that first emerged in Wuhan in December 2019 has resulted in the devastating pandemic of coronavirus disease 2019, creating an emerging need for knowledge sharing. Meanwhile, myocardial infarction is and will probably remain the foremost cause of death in the Western world throughout the coming decades. Severe deregulation of the immune system can unnecessarily expand the inflammatory response and participate in target and multiple organ failure, in infection but also in critical illness. Indeed, the course and fate of inflammatory cells observed in severe ST-elevation myocardial infarction (neutrophilia, monocytosis, and lymphopenia) almost perfectly mirror those recently reported in severe coronavirus disease 2019. A pleiotropic proinflammatory imbalance hampers adaptive immunity in favor of uncontrolled innate immunity and is associated with poorer structural and clinical outcomes. The goal of the present review is to gain greater insight into the cellular and molecular mechanisms underlying this canonical activation and downregulation of the two arms of the immune response in both entities, to better understand their pathophysiology and to open the door to innovative therapeutic options. Knowledge sharing can pave the way for therapies with the potential to significantly reduce mortality in both infectious and noninfectious scenarios.

T cell markers recount the course of immunosenescence in healthy individuals and chronic kidney disease

Aging results in substantial changes in almost all cellular subpopulations within the immune system, including functional and phenotypic alterations. T lymphocytes, as the main representative population of cellular immunity, have been extensively studied in terms of modifications and adjustments during aging. Phenotypic alterations are attributed to three main mechanisms; a reduction of naïve T cell population with a shift to more differentiated forms, a subsequent oligoclonal expansion of naïve T cells characterized by repertoire restriction, and replicative insufficiency after repetitive activation. These changes and the subsequent phenotypic disorders are comprised in the term "immunosenescence". Similar changes seem to occur in chronic kidney disease, with T cells of young patients resembling those of healthy older individuals. A broad range of surface markers can be utilized to identify immunosenescent T cells. In this review, we will discuss the most important senescence markers and their potential connection with impaired renal function.

Comparison of Clinical Outcomes of Induction Regimens in Patients Undergoing Liver Transplantation for Acute Liver Failure

Spontaneous survival rates in acute liver failure (ALF) are vastly improved by liver transplantation (LT). However, the value of induction agents beyond steroids continues to be debated. To understand the potential benefit of different induction regimens in the ALF population, we compared overall survival of recipients undergoing LT in the United States for ALF. Using the Scientific Registry of Transplant Recipients, we assessed the impact of induction immunosuppression (IS) in a cohort of 3754 first-time LT recipients with a diagnosis of ALF from 2002 to 2018. Induction IS therapy was grouped into steroid-only induction, use of antithymocyte globulin (ATG), or interleukin 2 receptor antibody. Other regimens were excluded from analysis. Survival analysis was estimated via Cox proportional hazards models and expressed as hazard ratios (HRs). In LT for ALF, the use of induction agents beyond steroids is increasingly frequent over the last 2 decades. The use of ATG is associated with worse overall survival, even after adjusting for donor and recipient factors, with HR of 1.24 (95% confidence interval, 1.00-1.53; P = 0.05). An elevated serum creatinine, recipient and donor age, and Black ethnicity, were all associated with reduced survival, whereas maintenance IS with calcineurin inhibitors (CNIs) was associated with improved survival. Although adjunct induction therapy has become more common, our analysis shows that compared with a steroid-only induction regimen, the addition of ATG is associated with worse overall survival after LT for ALF. CNI maintenance was highly protective, suggesting that an IS strategy focusing on corticosteroid-only induction followed by CNI maintenance may offer the best overall survival rate.

Time-dependent lymphocyte count after transplantation is associated with higher risk of graft failure and death

The transplantation field requires the identification of specific risk factors associated with the level of immunosuppression. Here, our aim was to analyze the association between the number of circulating lymphocytes, monitored routinely by complete blood cell counts during outpatient visits, and patient and graft survival. In total, 2,999 kidney or combined kidney-pancreas recipients transplanted between 2000 and 2016, from two University hospitals, were enrolled. We investigated the etiological relationship between time-dependent lymphocyte count beyond one year after transplantation and patient and graft survival, viral infection and cancer risk using time-dependent multivariate Cox models. Model 1 considered kidney function at one year and model 2 as time-dependent variable. At the time of inclusion (one year after transplantation), 584 patients (19.4%) had deep lymphopenia (under 750 /mm³) and 1,072 (35.7%) had a normal count (over 1,500 /mm³). A patient with deep lymphopenia at a given follow-up time had significantly higher risks of graft failure, death and viral infection than comparable patients with a normal lymphocyte count at the same time point. Thus, after the first year of transplantation, the occurrence of deep lymphopenia within a patient's follow-up is a risk factor for long-term graft failure, death and viral infection.

BK Polyomavirus-Specific CD8 T-Cell Expansion In Vitro Using 27mer Peptide Antigens for Developing Adoptive T-Cell Transfer and Vaccination

BACKGROUND

BK polyomavirus (BKPyV) remains a significant cause of premature kidney transplant failure. In the absence of effective antivirals, current treatments rely on reducing immunosuppression to regain immune control over BKPyV replication. Increasing BKPyV-specific CD8 T cells correlate with clearance of BKPyV DNAemia in kidney transplant patients. We characterized a novel approach for expanding BKPyV-specific CD8 T cells in vitro using 27mer-long synthetic BKPyV peptides, different types of antigen-presenting cells, and CD4 T cells.

METHODS

Langerhans cells and immature or mature monocyte-derived dendritic cells (Mo-DCs) were generated from peripheral blood mononuclear cells of healthy blood donors, pulsed with synthetic peptide pools consisting of 36 overlapping 27mers (27mP) or 180 15mers (15mP). BKPyV-specific CD8 T-cell responses were assessed by cytokine release assays using 15mP or immunodominant 9mers.

RESULTS

BKPyV-specific CD8 T cells expanded using 27mP and required mature Mo-DCs (P = .0312) and CD4 T cells (P = .0156) for highest responses. The resulting BKPyV-specific CD8 T cells proliferated, secreted multiple cytokines including interferon γ and tumor necrosis factor α, and were functional (CD107a+/PD1-) and cytotoxic.

CONCLUSIONS

Synthetic 27mP permit expanding BKPyV-specific CD8 T-cell responses when pulsing mature Mo-DCs in presence of CD4 T cells, suggesting novel and safe approaches to vaccination and adoptive T-cell therapies for patients before and after kidney transplantation.

Pre-transplant Thymic Function Predicts Is Associated With Patient Death After Kidney Transplantation

Accelerated thymic involution is a main feature of end-stage renal disease (ESRD)-associated immune senescence. Recent evidences suggest that ESRD-associated immune senescence is associated with adverse outcomes in dialysis patients. However, no study focused on the association between pre-transplant thymic function and patient survival after transplantation. We conducted a prospective, multicenter study to assess whether pre-transplant thymic function measured by recent thymic emigrants (RTE) may predict death after first kidney transplantation. Results were tested in a validation cohort. Nine hundred and sixty-seven incident kidney transplant recipients were included in the prospective study. Mean follow up was 5.1 + 2.9 years. Eighty two patients (8.5%) died during follow up. Lower RTE levels were associated with a higher risk of death (2.53; 95%CI, 1.54–4.39 for each decrease of 1 log in RTE; p < 0.001). Cancer-related death was particularly increased in patients with low RTE levels (4.23; 95%CI, 1.43–12.13; p = 0.007). One hundred and thirty-six patients having received a first kidney transplantation were included in the validation cohort. Lower TREC levels were associated with higher risk of death (1.90; 95%CI, 1.11–3.51 for each decrease of 1 log in RTE; p = 0.025). RTE were not associated with death-censored graft loss. Pre-transplant thymic function is strongly associated with death after transplantation. Attempt to reverse ESRD-related thymic loss may prevent premature death.

Idiopathic CD4 Lymphocytopenia: Current Insights

Idiopathic CD4 lymphocytopenia is a condition characterized by low CD4 counts. It is rare and most of the information about this illness comes from case reports. Presentation is usually in the 4th decade of life with opportunistic infections, autoimmune disease or neoplasia. The pathophysiology of this condition is not well understood. Management revolves around treatment of the presenting condition and close follow-up of these patients. This review presents a narrative summary of the current literature on idiopathic CD4 lymphocytopenia.

Thymoglobulin vs. ATG-Fresenius as Induction Therapy in Kidney Transplantation: A Bayesian Network Meta-Analysis of Randomized Controlled Trials

Background: Thymoglobulin (THG) and antithymocyte globulin-Fresenius (ATG-F) have not been compared directly as induction therapies in kidney transplantation. Materials and Methods: We performed a Bayesian network meta-analysis to compare THG with ATG-F by pooling direct and indirect evidence. Surface under the cumulative ranking curve (SUCRA) values were used to compare the superiority of one method over the other. Results: A total of 27 randomized controlled trials (RCT) were eligible for the network meta-analysis. Efficacy endpoints, as well as safety indicators, were statistically comparable. For efficacy endpoints, THG seemed inferior to ATG-F in preventing delayed graft function [odds ratio (OR): 1.27; SUCRA: 78% vs. 58%], patient deaths (OR: 2.78; SUCRA: 83% vs. 34%), and graft loss (OR: 1.40; SUCRA: 83% vs. 59%), but superior to ATG-F in biopsy-proven acute rejection (BPAR; OR: 0.59; SUCRA: 78% vs. 39%) and steroid-resistant BPAR prevention (OR: 0.61; SUCRA: 76% vs. 49%) within the first year. For safety endpoints, THG was associated with higher risk of infection (OR: 1.49, SUCRA: 79% vs. 54%), cytomegalovirus infection (OR: 1.04; SUCRA: 40% vs. 37%), de novo diabetes (OR: 1.10; SUCRA: 90% vs. 30%), and malignancy (OR: 8.40; SUCRA: 89% vs. 6%) compared to ATG-F. A subgroup analysis of patients at high risk for immunologic complications revealed similar results, but THG performed better for graft loss (OR: 0.82; SUCRA: 68% vs. 54%). Conclusion: ATG-F seemed to be more effective than THG in improving the short-term kidney transplantation outcomes. Prospective head-to-head comparison of THG and ATG-F with larger sample sizes and longer follow-up is still required.

Uremia-Associated Ageing of the Thymus and Adaptive Immune Responses

Progressive loss of renal function is associated with a series of changes of the adaptive immune system which collectively constitute premature immunological ageing. This phenomenon contributes significantly to the mortality and morbidity of end-stage renal disease (ESRD) patients. In this review, the effect of ESRD on the T cell part of the adaptive immune system is highlighted. Naïve T cell lymphopenia, in combination with the expansion of highly differentiated memory T cells, are the hallmarks of immunological ageing. The decreased production of newly formed T cells by the thymus is critically involved. This affects both the CD4 and CD8 T cell compartment and may contribute to the expansion of memory T cells. The expanding populations of memory T cells have a pro-inflammatory phenotype, add to low-grade inflammation already present in ESRD patients and destabilize atherosclerotic plaques. The effect of loss of renal function on the thymus is not reversed after restoring renal function by kidney transplantation and constitutes a long-term mortality risk factor. Promising results from animal experiments have shown that rejuvenation of the thymus is a possibility, although not yet applicable in humans.

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 very low thymus function identifies patients with substantial increased risk for long-term mortality after kidney transplantation

Background

End-stage renal disease is associated with premature ageing of the T cell immune system but inter-individual variation is substantial. The hypothesis was tested that advanced immunological T cell ageing assessed by peripheral T cell differentiation increases the long-term mortality risk after renal transplantation.

Results

Circulating T cells of 211 recipients of a kidney from a living donor were analyzed before and in the first year after transplantation. The number of CD31-positive naive T cells (as a marker for recent thymic emigrants) and the differentiation status of the memory T cells was assessed. Thirty recipients died during follow-up of at least 5 years. Absolute numbers of naive CD4⁺ (living:258 cells/μl vs. deceased:101 cells/μl, p < 0.001) and naive CD8⁺ T cells (living:97 cells/μl vs. deceased:37 cells/μl, p < 0.001) were significantly lower in the deceased group prior to transplantation. In a multivariate proportional hazard analysis the number of naive CD4⁺ T cells remained associated with all-cause mortality (HR 0.98, CI 0.98–0.99, p < 0.001). The low number of naive T cells in the deceased patient group was primarily caused by a decrease in recent thymic emigrants (i.e. less CD31⁺ naive T cells) indicating a lowered thymus function. In addition, the physiological age-related compensatory increase in CD31⁻ naïve T cells was not observed. Within the first year after transplantation, the number and characteristics of naive T cells remained stable.

Conclusions

A severe reduction in circulating naïve T cells because of a decrease in recent thymic emigrants is highly associated with all-cause mortality after renal transplantation.

T cell reconstitution after lymphocyte depletion features a different pattern of inhibitory receptor expression in ABO- versus HLA-incompatible kidney transplant recipients

Chronic antigen stimulation can lead to immune exhaustion (a state of T cell dysfunction). Several phenotypical signatures of T cell exhaustion have been described in various pathological situations, characterized by aberrant expression of multiple inhibitory receptors (IR). This signature has been barely studied in the context of allogenic organ transplantation. We undertook a cross-sectional analysis of the expression of IR [CD244, CD279, T cell immunoreceptor with immunoglobulin (Ig) and immunoreceptor tyrosine-based inhibition motif (ITIM) domains (TIGIT) and CD57] and their correlation with cytokine-producing functions in T cells reconstituting after lymphocyte depletion in patients transplanted from living donors, with preformed donor-specific antibodies. After ABO incompatible transplantation, T cells progressively acquired a phenotype similar to healthy donors and the expression of several IR marked cells with increased functions, with the exception of TIGIT, which was associated with decreased cytokine production. In stark contrast, T cell reconstitution in patients with anti-human leukocyte antigen (HLA) antibodies was characterized with an increased co-expression of IR by T cells, and specifically by an increased expression of TIGIT. Furthermore, expression of these receptors was no longer directly correlated to cytokine production. These results suggest that T cell alloreactivity in HLA-incompatible kidney transplantation drives an aberrant T cell reconstitution with respect to IR profile, which could have an impact on the transplantation outcome.

[Premature immune senescence and chronic kidney disease: Update and perspectives]

Immune senescence is associated with age-related diseases (i.e. infectious disease, cardiovascular diseases and cancers). Chronic kidney disease patients die prematurely when compared with general population, because of a higher occurrence of infections, cardiovascular events and cancer. These diseases are commonly observed in the elderly population and frequently associated with immune senescence. Indeed, chronic kidney disease causes a premature aging of the T lymphocyte compartment, widely related to a decrease in thymic function, a phenomenon that plays a key role in the onset of age-related diseases in chronic kidney disease patients. The degree of immune senescence also influences patients' outcome after renal transplantation, particularly the risk of acute rejection and infections. Partial reversion of pre-transplant immune senescence is observed for some renal transplant patients. In conclusion, to reduce the increasing incidence of morbidity and mortality of chronic kidney disease patients, a better knowledge of uremia-induced immune senescence would help to pave the way to build clinical studies and promote innovative therapeutic approaches. We believe that therapeutic reversion and immune senescence prevention approaches will be part of the management of chronic kidney disease patients in the future.

Pretransplant Levels of C-Reactive Protein, Soluble TNF Receptor-1, and CD38+HLADR+ CD8 T Cells Predict Risk of Allograft Rejection in HIV+ Kidney Transplant Recipients

INTRODUCTION

HIV-positive (HIV+) kidney transplant recipients exhibit a 2- to 3-fold increased risk of allograft rejection. Dysregulated immune activation in HIV infection persists despite successful antiretroviral therapy and is associated with non-AIDS morbidity, including renal disease. We hypothesized that the pathological levels of inflammation and immune activation associated with chronic HIV infection could have clinical utility in the prediction of rejection in HIV+ kidney recipients.

METHODS

Prospective cohort study of 22 HIV-negative (HIV-; donor) to HIV+ (recipient) kidney transplant recipients who underwent biomarker assessment pretransplant and were subsequently followed for development of acute rejection. Plasma levels of markers of inflammation (soluble tumor necrosis factor receptor 1 [sTNF-R1] and C-reactive protein [CRP]) and microbial translocation (soluble CD14 and lipopolysaccharide) were measured by enzyme-linked immunosorbent assay or chromogenic endpoint assay. Levels of activated (CD38+HLADR+) CD4+ and CD8+ T cells, and T regulatory cells (CD4+CD25highFoxP3+) were measured by flow cytometry.

RESULTS

Among the biomarkers evaluated, only the pretransplant levels of sTNF-R1, CRP, and frequencies of CD38+HLADR+ CD8 T cells, were found to be at significantly higher levels among patients who experienced biopsy-proven acute rejection. Confirming our hypothesis, patients with high pretransplant levels of sTNF-R1 or activated CD8+ T cells had a significantly increased 200-day cumulative incidence of biopsy-proven acute rejection (0 vs. 38% for both; P = 0.01). Similarly, pretransplant CRP levels higher than 5 μg/ml were associated with increased risk of acute rejection within the first 6 months post-transplant (0 vs. 43%; P = 0.01).

CONCLUSION

Biomarker-based identification of HIV+ recipients at increased risk for rejection might facilitate individualized induction immunosuppression regimens in this vulnerable patient population.

Hereditary polycystic kidney disease is characterized by lymphopenia across all stages of kidney dysfunction: an observational study

Background

Polycystic kidney disease (PKD) is characterized by urinary tract infections and extrarenal abnormalities such as an increased risk of cancer. As mutations in polycystin-1 and -2 are associated with decreased proliferation of immortalized lymphoblastoid cells in PKD, we investigated whether lymphopenia could be an unrecognized trait of PKD.

Methods

We studied 700 kidney transplant recipients with (n = 126) or without PKD at the time of kidney transplantation between 1 January 2003 and 31 December 2014 at Ghent University Hospital. We also studied 204 patients with chronic kidney disease (CKD) with PKD and 204 matched CKD patients without PKD across comparable CKD strata with assessment between 1 January 1999 and 1 February 2016 at three renal outpatient clinics. We compared lymphocyte counts with multiple linear regression analysis to adjust for potential confounders. We analysed flow cytometric immunophenotyping data and other haematological parameters.

Results

Lymphocyte counts were 264/µL [95% confidence interval (CI) 144-384] and 345/µL (95% CI 245-445) (both P < 0.001) lower in the end-stage kidney disease (ESKD) and CKD cohort, respectively, after adjustment for age, sex, ln(C-reactive protein) and estimated glomerular filtration rate (in the CKD cohort only). In particular, CD8+ T and B lymphocytes were significantly lower in transplant recipients with versus without PKD (P < 0.001 for both). Thrombocyte and monocyte counts were lower in patients with versus without PKD in both cohorts (P < 0.001 for all analyses except P = 0.01 for monocytes in the ESKD cohort).

Conclusion

PKD is characterized by distinct cytopenias and especially lymphopenia, independent of kidney function. This finding has the potential to alter our therapeutic approach to patients with PKD.

Induction immunosuppression agents as risk factors for incident cardiovascular events and mortality after kidney transplantation

Low T cell counts and acute rejection are associated with increased cardiovascular events (CVEs); T cell-depleting agents decrease both. Thus, we aimed to characterize the risk of CVEs by using an induction agent used in kidney transplant recipients. We conducted a secondary data analysis of patients who received a kidney transplant and used Medicare as their primary insurance from 1999 to 2010. Outcomes of interest were incident CVE, all-cause mortality, CVE-related mortality, and a composite outcome of mortality and CVE. Of 47 258 recipients, 29.3% received IL-2 receptor antagonist (IL-2RA), 33.3% received anti-thymocyte globulin (ATG), 7.3% received alemtuzumab, and 30.0% received no induction. Compared with IL-2RA, there was no difference in the risk of CVE in the ATG (adjusted hazard ratio [aHR] 0.98, 95% confidence interval [CI] 0.92-1.05) and alemtuzumab group (aHR 1.01, 95% CI 0.89-1.16), but slightly higher in the no induction group (aHR 1.06, 95% CI 1.00-1.14). Acute rejection did not modify this association in the latter group but did increase CVE by 46% in the alemtuzumab group. There was no difference in the hazard of all-cause or CVE-related mortality. Only in the ATG group, a 7% lower hazard of the composite outcome of mortality and CVE was noted. Induction agents are not associated with incident CVE, although prospective trials are needed to determine a personalized approach to prevention.

ESRD-associated immune phenotype depends on dialysis modality and iron status: clinical implications

BACKGROUND

End-stage renal disease (ESRD) causes premature ageing of the immune system. However, it is not known whether hemodialysis (HD) and peritoneal dialysis (PD) similarly affect the T cell system.

METHODS

The aim of our study was to analyse whether dialysis modality may mitigate ESRD-induced immune senescence. We explored a large population of patients (675 ESRD patients) and both confirmed and refined the results in a second cohort (84 patients).

RESULTS

HD patients exhibited higher inflammatory monocytes counts (44/mm3 (1-520) vs 36/mm3 (1-161); p = 0.005). Patients on HD also had higher frequency of CD8 T cells (24% (7-61) vs 22% (8-42); p = 0.003) and reduced CD4/CD8 ratio. Such results were confirmed in the second cohort. Moreover, both CD4 + CD57 + CD28- (3.25% (0-38.2) vs 1.05% (0-28.5); p = 0.068) and CD8 + CD57 + CD28- (38.5% (3.6-76.8) vs 26.1 (2.1-46.9); p = 0.039) T cells frequencies were increased in HD patients. Telomere length did not differ according to dialysis modality, but was inversely related to ferritin levels (r = - 0.33; p = 0.003). There was a trend towards higher telomerase activity in PD patients (11 ± 13 vs 6 ± 11; p = 0.053). Thymic function was not different in PD and HD patients. Patients on PD before transplantation had a higher risk of acute rejection after kidney transplantation (HR, 1.61; 95%CI, 1.02 to 2.56; p = 0.041).

CONCLUSIONS

More pronounced inflammation with hemodialysis may induce premature aging of the immune system. This observation correlates with a lower risk of acute kidney rejection in patients previously on HD. Clinical consequences in patients maintained on dialysis should be determined.

TRIAL REGISTRATION

Trial registration: NCT02843867, registered July 8, 2016.

Posttransplant Immune Activation: Innocent Bystander or Insidious Culprit of Posttransplant Accelerated Atherosclerosis

Cardiovascular disease is a major cause of morbidity, disability, and mortality in kidney transplant patients. Cumulative reports indicate that the excessive risk of cardiovascular events is not entirely explained by the increased prevalence of traditional cardiovascular risk factors. Atherosclerosis is a chronic inflammatory disease, and it has been postulated that posttransplant immune disturbances may explain the gap between the predicted and observed risks of cardiovascular events. Although concordant data suggest that innate immunity contributes to the posttransplant accelerated atherosclerosis, only few arguments plead for a role of adaptive immunity. We report and discuss here consistent data demonstrating that CD8⁺ T cell activation is a frequent posttransplant immune feature that may have pro-atherogenic effects. Expansion of exhausted/activated CD8⁺ T cells in kidney transplant recipients is stimulated by several factors including cytomegalovirus infections, lymphodepletive therapy (e.g., antithymocyte globulins), chronic allogeneic stimulation, and a past history of renal insufficiency. This is observed in the setting of decreased thymic activity, a process also found in elderly individuals and reflecting accelerated immune senescence.

Anti-thymocyte globulins in kidney transplantation: focus on current indications and long-term immunological side effects

Antithymocyte globulins (ATGs) are part of the immunosuppression arsenal currently used by clinicians to prevent or treat acute rejection in solid organ transplantation. ATG is a mixture of non-specific anti-lymphocyte immunoglobulins targeting not only T cell subsets but also several other immune and non-immune cells, rendering its precise immunoglobulin composition difficult to appreciate or to compare from one preparation to another. Furthermore, several mechanisms of action have been described. Taken together, this probably explains the efficacy and the side effects associated with this drug. Recent data suggest a long-term negative impact on allograft and patient outcomes, pointing out the need to better characterize the potential toxicity and the benefit-risk balance associated to this immunosuppressive therapy within large clinical trials.

Antithymocyte globulins in renal transplantation-from lymphocyte depletion to lymphocyte activation: The doubled-edged sword

Compelling data suggest that lymphocyte depletion following T cell depleting therapy may induce prolonged CD4 T cell lymphopenia and trigger lymphocyte activation in some patients. These profound and non-reversible immune changes in T cell pool subsets are the consequence of both impaired thymic renewal and peripheral homeostatic proliferation. Chronic viral challenges by CMV play a major role in these immune alterations. Even when the consequences of CD4 T cell lymphopenia have been now well described, recent studies shed new light on the clinical consequences of immune activation. In this review, we will first focus on the mechanisms involved in T cell pool reconstitution after T cell depletion and further consider the clinical consequences of ATG-induced T cell activation and senescence in renal transplant recipients.

Efficacy and Safety of ATG-Fresenius as an Induction Agent in Living-Donor Kidney Transplantation

BACKGROUND

Induction therapy is mostly recommended for deceased-donor transplantation, whereas it has some controversies in live-donor transplantation. In this study, we described the outcomes of live-donor renal transplant recipients who received ATG-Fresenius (ATG-F) induction.

METHODS

Live-donor transplantations in patients over 18 years old with ATG-F induction between 2009 and 2015 were included. All patients received quadruple immunosuppression, one of which was ATG-F induction. Biopsies after the artery anastomosis (zero hour) and protocol biopsies at the 6th month and at the 1st first year were obtained. Acute graft dysfunction was defined as a 20% to 25% increase in creatinine level from baseline. All acute rejection episodes were biopsy-confirmed. All episodes were initially treated with intravenous methyl prednisolone (MP) or ATG-F if resistant to MP. Four hundred twenty-two patients with live-donor transplantation were evaluated. The mean age was 40 ± 13 (18-73) years. The mean panel-reactive antibody levels were 42% ± 30% and 45% ± 30% for class I and II, respectively.

RESULTS

The mean mismatch number for living unrelated donors (n = 112) was 4.6 ± 1.0. Acute rejection rate was 29.1% (123 patients) within the first year. The mean cumulative ATG-F doses for per patient and per kilogram were 344 ± 217 mg and 5.1 ± 2.7 mg, respectively. Patient survival rates were 98.3% and 96.7% for 12 months and 60 months, respectively. Death-censored graft survival rates were 97.6% and 92.1% for 12 months and 60 months, respectively.

CONCLUSIONS

ATG-F induction provided excellent graft and patient survival rates without any significantly increased side effects. Increasing sensitized patient numbers, more unrelated donors, increasing re-transplantation numbers, and more desensitization protocols make ATG-F more favorable in an induction regimen.

Uremia-Associated Premature Aging of T Cells Does Not Predict Infectious Complications After Renal Transplantation

Patients with end-stage renal disease have prematurely aged T cell systems. We tested whether T cell aging parameters were associated with the risk of infections after renal transplantation (RTx). We studied 188 patients over 1 year. Peripheral T cells were analyzed before and at 3 and 6 mo after RTx for frequency of recent thymic emigrants, relative telomere length and differentiation status. These parameters were related to the occurrence of opportunistic and serious infections. Overall, 84 patients developed an infection. In this group, 50 developed an opportunistic infection and 53 developed a serious infection. T cell aging parameters assessed before RTx were not associated with infection risk. The memory T cells showed a decrease within the first 3 mo in both groups (p < 0.001). The CD4(+) memory T cells increased between 3 and 6 mo within the infection group (p = 0.015). The number of CD8(+) memory T cells increased in both groups (p < 0.001) but reached baseline levels only in the infection group. In the infection group, the CD8(+) CD28(null) T cell percentage increased between 3 and 6 mo (p = 0.024), tending to be higher than at baseline (p = 0.061). These differences in post-RTx dynamics resulted from infections. Parameters of uremia-associated premature aging of peripheral T cells do not predict posttransplant infections.

Pretransplant CD4 Count Influences Immune Reconstitution and Risk of Infectious Complications in Human Immunodeficiency Virus-Infected Kidney Allograft Recipients

In current practice, human immunodeficiency virus-infected (HIV(+) ) candidates with CD4 >200 cells/mm(3) are eligible for kidney transplantation; however, the optimal pretransplant CD4 count above this threshold remains to be defined. We evaluated clinical outcomes in patients with baseline CD4 >350 and <350 cells/mm(3) among 38 anti-thymocyte globulin (ATG)-treated HIV-negative to HIV(+) kidney transplants performed at our center between 2006 and 2013. Median follow-up was 2.6 years. Rates of acute rejection and patient and graft survival were not different between groups. Occurrence of severe CD4 lymphopenia (<200 cells/mm(3) ), however, was more common among patients with a baseline CD4 count 200-349 cells/mm(3) compared with those transplanted at higher counts (75% vs. 30% at 4 weeks [p = 0.04] and 71% vs. 5% at 52 weeks [p = 0.001], respectively, after transplant). After adjusting for age, baseline CD4 count of 200-349 cells/mm(3) was an independent predictor of severe CD4 lymphopenia at 4 weeks (relative risk [RR] 2.6; 95% confidence interval [CI] 1.3-5.1) and 52 weeks (RR 14.3; 95% CI 2-100.4) after transplant. Patients with CD4 <200 cells/mm(3) at 4 weeks had higher probability of serious infections during first 6 months after transplant (19% vs. 50%; log-rank p = 0.05). These findings suggest that ATG must be used with caution in HIV(+) kidney allograft recipients with a pretransplant CD4 count <350 cells/mm(3) .

Concise Review: Apoptotic Cell-Based Therapies-Rationale, Preclinical Results and Future Clinical Developments

The objectives of this review are to summarize the experimental data obtained using apoptotic cell-based therapies, and then to discuss future clinical developments. Indeed, apoptotic cells exhibit immunomodulatory properties that are reviewed here by focusing on more recent mechanisms. These immunomodulatory mechanisms are in particular linked to the clearance of apoptotic cells (called also efferocytosis) by phagocytes, such as macrophages, and the induction of regulatory T cells. Thus, apoptotic cell-based therapies have been used to prevent or treat experimental inflammatory diseases. Based on these studies, we have identified critical steps to design future clinical trials. This includes: the administration route, the number and schedule of administration, the appropriate apoptotic cell type to be used, as well as the apoptotic signal. We also have analyzed the clinical relevancy of apoptotic-cell-based therapies in experimental models. Additional experimental data are required concerning the treatment of inflammatory diseases (excepted for sepsis) before considering future clinical trials. In contrast, apoptotic cells have been shown to favor engraftment and to reduce acute graft-versus-host disease (GvHD) in different relevant models of transplantation. This has led to the conduct of a phase 1/2a clinical trial to alleviate GvHD. The absence of toxic effects obtained in this trial may support the development of other clinical studies based on this new cell therapy. Stem Cells 2016;34:1464-1473.

Pemphigus vulgaris-associated interstitial lung disease

Autoimmune bullous diseases (AIBDs)-associated interstitial lung disease (ILD) is extremely rare. Pemphigus vulgaris (PV) is an intraepidermal autoimmune blistering disease caused by circulating autoantibodies against desmoglein. To date, PV-associated ILD has rarely been reported in English literature. We report a rare association of PV and ILD. A 53-year-old Chinese female with PV for 8 months developed ILD after a relapse of PV for 2 months due to discontinuation of oral prednisone by herself. She was successfully treated by systemic methylprednisolone. Taken previously reported bullous pemphigoid-associated ILD and linear IgA/IgG bullous dermatosis-associated ILD together, in general, AIBDs-associated ILD occurs when AIBDs relapse or are not controlled, responds well to systemic corticosteroids, and has a relatively better prognosis when compared with rheumatoid arthritis- or dermatomyositis-associated ILD.

Pretransplant thymic function predicts acute rejection in antithymocyte globulin-treated renal transplant recipients

Lack of clear identification of patients at high risk of acute rejection hampers the ability to individualize immunosuppressive therapy. Here we studied whether thymic function may predict acute rejection in antithymocyte globulin (ATG)-treated renal transplant recipients in 482 patients prospectively studied during the first year post-transplant of which 86 patients experienced acute rejection. Only CD45RA(+)CD31(+)CD4(+) T cell (recent thymic emigrant [RTE]) frequency (RTE%) was marginally associated with acute rejection in the whole population. This T-cell subset accounts for 26% of CD4(+) T cells. Pretransplant RTE% was significantly associated with acute rejection in ATG-treated patients (hazard ratio, 1.04; 95% confidence interval, 1.01-1.08) for each increased percent in RTE/CD4(+) T cells), but not in anti-CD25 monoclonal (αCD25 mAb)-treated patients. Acute rejection was significantly more frequent in ATG-treated patients with high pretransplant RTE% (31.2% vs. 16.4%) or absolute number of RTE/mm(3) (31.7 vs. 16.1). This difference was not found in αCD25 monclonal antibody-treated patients. Highest values of both RTE% (>31%, hazard ratio, 2.50; 95% confidence interval, 1.09-5.74) and RTE/mm(3) (>200/mm(3), hazard ratio, 3.71; 95% confidence interval, 1.59-8.70) were predictive of acute rejection in ATG-treated patients but not in patients having received αCD25 monoclonal antibody). Results were confirmed in a retrospective cohort using T-cell receptor excision circle levels as a marker of thymic function. Thus, pretransplant thymic function predicts acute rejection in ATG-treated patients.

A Rationale for Age-Adapted Immunosuppression in Organ Transplantation

Demographic changes are associated with a steady increase of older patients with end-stage organ failure in need for transplantation. As a result, the majority of transplant recipients are currently older than 50 years, and organs from elderly donors are more frequently used. Nevertheless, the benefit of transplantation in older patients is well recognized, whereas the most frequent causes of death among older recipients are potentially linked to side effects of their immunosuppressants.Immunosenescence is a physiological part of aging linked to higher rates of diabetes, bacterial infections, and malignancies representing the major causes of death in older patients. These age-related changes impact older transplant candidates and may have significant implications for an age-adapted immunosuppression. For instance, immunosenescence is linked to lower rates of acute rejections in older recipients, whereas the engraftment of older organs has been associated with higher rejection rates. Moreover, new-onset diabetes mellitus after transplantation is more frequent in the elderly, potentially related to corticosteroids, calcineurin inhibitors, and mechanistic target of rapamycin inhibitors.This review presents current knowledge for an age-adapted immunosuppression based on both, experimental and clinical studies in and beyond transplantation. Recommendations of maintenance and induction therapy may help to improve graft function and to design future clinical trials in the elderly.

Juvenile generalized pustular psoriasis with IL36RN mutation treated with short-term infliximab

A 8-year-old Chinese boy with generalized pustular psoriasis (GPP) refractory to cyclosporine and methylprednisolone was treated successfully with two infusions of infliximab 3.3 mg/kg. He remained in remission for 21 months. Direct sequencing of IL36RN gene showed a homozygous mutation, c.115 + 6T>C. Juvenile GPP is a rare severe form of psoriasis occasionally associated with life-threatening complications. Like acitretin, cyclosporine and methotrexate, infliximab has been reported to be effective for juvenile GPP in case reports. However, there is a lack of data in the optimal treatment course of infliximab for juvenile GPP. Prolonged administration of these medications may cause toxic or fatal complications. We suggest that short-term infliximab regimen should be recommended as a choice for acute juvenile GPP refractory to traditional systemic therapies. WBC count and CRP are sensitive parameters to reflect the disease activity and evaluate the effectiveness of treatment. Monitoring CD4 T lymphocyte count, preventing and correcting CD4 lymphocytopenia are important in the treatment course of juvenile GPP.