Premature aging of circulating T cells in patients with end-stage renal disease. Kidney Int. 2011;80:208-217. [PMID: 21525849 DOI: 10.1038/ki.2011.110]

Hemogram-Derived Inflammatory Markers in Cats with Chronic Kidney Disease

Chronic kidney disease (CKD) is characterized by chronic inflammation, which mediates the progressive replacement of functional nephrons by fibrotic tissue. Hemogram-derived inflammatory markers are known to serve as markers of pathological conditions; however, their diagnostic value in feline CKD is still unknown. The aim of this retrospective study was to investigate selected hemogram-derived inflammatory markers (neutrophil-to-lymphocyte ratio (NLR), monocyte-to-lymphocyte ratio (MLR), platelet-to-lymphocyte ratio (PLR) and the systemic immune-inflammatory index (SII)) in cats at different clinical stages of CKD. Eighty-eight client-owned cats with CKD and thirty-two healthy control cats were included. Cats with CKD were divided into two groups: early CKD (IRIS stage 1 and 2; 62 cats) and progressed CKD (IRIS stage 3 and 4; 26 cats). The values of inflammatory markers were compared between the two CKD groups and the control group. All investigated hemogram-derived inflammatory markers were significantly (p < 0.05) greater in cats with advanced CKD than in those in the other two groups. Additionally, we demonstrated a statistically significant weak to moderate correlation between serum urea, creatinine, selected hematologic and urinary parameters, and the investigated inflammatory markers in cats with CKD. Chronic inflammation can be easily and inexpensively assessed with hemogram-derived markers.

Interleukin-16 is increased in dialysis patients but is not a cardiovascular risk factor

Oxalate, a uremic toxin that accumulates in dialysis patients, is associated with cardiovascular disease. As oxalate crystals can activate immune cells, we tested the hypothesis that plasma oxalate would be associated with cytokine concentrations and cardiovascular outcomes in dialysis patients. In a cohort of 104 US patients with kidney failure requiring dialysis (cohort 1), we measured 21 inflammatory markers. As IL-16 was the only cytokine to correlate with oxalate, we focused further investigations on IL-16. We searched for associations between concentrations of IL-16 and mortality and cardiovascular events in the 4D cohort (1255 patients, cohort 2) and assessed further associations of IL-16 with other uremic toxins in this cohort. IL-16 levels were positively correlated with pOx concentrations (ρ = 0.39 in cohort 1, r = 0.35 in cohort 2) and were elevated in dialysis patients when compared to healthy individuals. No significant association could be found between IL-16 levels and cardiovascular events or mortality in the 4D cohort. We conclude that the cytokine IL-16 correlates with plasma oxalate concentrations and is substantially increased in patients with kidney failure on dialysis. However, no association could be detected between IL-16 concentrations and cardiovascular disease in the 4D cohort.

Podocyte Ercc1 is indispensable for glomerular integrity

As life expectancy continues to increase, age-related kidney diseases are becoming more prevalent. Chronic kidney disease (CKD) is not only a consequence of aging but also a potential accelerator of aging process. Here we report the pivotal role of podocyte ERCC1, a DNA repair factor, in maintaining glomerular integrity and a potential effect on multiple organs. Podocyte-specific ERCC1-knockout mice developed severe proteinuria, glomerulosclerosis, and renal failure, accompanied by a significant increase in glomerular DNA single-strand breaks (SSBs) and double-strand breaks (DSBs). ERCC1 gene transfer experiment in the knockout mice attenuated proteinuria and glomerulosclerosis with reduced DNA damage. Notably, CD44+CD8+ memory T cells, indicative of T-cell senescence, were already elevated in the peripheral blood of knockout mice at 10 weeks old. Additionally, levels of senescence-associated secretory phenotype (SASP) factors were significantly increased in both the circulation and multiple organs of the knockout mice. In older mice and human patients, we observed an accumulation of DSBs and an even greater buildup of SSBs in glomeruli, despite no significant reduction in ERCC1 expression with age in mice. Collectively, our findings highlight the crucial role of ERCC1 in repairing podocyte DNA damage, with potential implications for inflammation in various organs.

Immunosenescence, gut dysbiosis, and chronic kidney disease: Interplay and implications for clinical management

Immunosenescence refers to the immune system changes observed in individuals over 50 years old, characterized by diminished immune response and chronic inflammation. Recent investigations have highlighted similar immune alterations in patients with reduced kidney function. The immune system and kidney function have been found to be closely interconnected. Studies have shown that as kidney function declines, both innate and adaptive immunity are affected. Chronic kidney disease (CKD) patients exhibit decreased levels of naive and regular T cells, as well as naive and memory B cells, while memory T cell counts increase. Furthermore, research suggests that CKD and end-stage kidney disease (ESKD) patients experience early thymic dysfunction and heightened homeostatic proliferation of naive T cells. In addition to reduced thymic T cell production, CKD patients display shorter telomeres in both CD4+ and CD8+ T cells. Declining kidney function induces uremic conditions, which alter the intestinal metabolic environment and promote pathogen overgrowth while reducing diversity. This dysbiosis-driven imbalance in the gut microbiota can result in elevated production of uremic toxins, which, in turn, enter the systemic circulation due to compromised gut barrier function under uremic conditions. The accumulation of gut-derived uremic toxins exacerbates local and systemic kidney inflammation. Immune-mediated kidney damage occurs due to the activation of immune cells in the intestine as a consequence of dysbiosis, leading to the production of cytokines and soluble urokinase-type plasminogen activator receptor (suPAR), thereby contributing to kidney inflammation. In this review, we delve into the fundamental mechanisms of immunosenescence in CKD, encompassing alterations in adaptive immunity, gut dysbiosis, and an overview of the clinical findings pertaining to immunosenescence.

Impact of Immunosenescence in Older Kidney Transplant Recipients: Associated Clinical Outcomes and Possible Risk Stratification for Immunosuppression Reduction

The number of older individuals receiving a kidney transplant as replacement therapy has significantly increased in the past decades and this increase is expected to continue. Older patients have a lower rate of acute rejection but an increased incidence of death with a functioning graft. Several factors, including an increased incidence of infections, post-transplant malignancy and cardiovascular comorbidity and mortality, contribute to this increased risk. Notwithstanding, kidney transplantation is still the best form of kidney replacement therapy in all patients with chronic kidney disease, including in older individuals. The best form of immunosuppression and the optimal dose of these medications in older recipients remains a topic of discussion. Pharmacological studies have usually excluded older patients and when included, patients were highly selected and their numbers insignificant to draw a reasonable conclusion. The reduced incidence of acute rejection in older recipients has largely been attributed to immunosenescence. Immunosenescence refers to the aging of the innate and adaptive immunity, accumulating in phenotypic and functional changes. These changes influences the response of the immune system to new challenges. In older individuals, immunosenescence is associated with increased susceptibility to infectious pathogens, a decreased response after vaccinations, increased risk of malignancies and cardiovascular morbidity and mortality. Chronic kidney disease is associated with premature immunosenescent changes, and these are independent of aging. The immunosenescent state is associated with low-grade sterile inflammation termed inflammaging. This chronic low-grade inflammation triggers a compensatory immunosuppressive state to avoid further tissue damage, leaving older individuals with chronic kidney disease in an immune-impaired state before kidney transplantation. Immunosuppression after transplantation may further enhance progression of this immunosenescent state. This review covers the role of immunosenescence in older kidney transplant recipients and it details present knowledge of the changes in chronic kidney disease and after transplantation. The impact of immunosuppression on the progression and complications of an immunosenescent state are discussed, and the future direction of a possible clinical implementation of immunosenescence to individualize/reduce immunosuppression in older recipients is laid out.

Anogenital distribution of mucosal HPV in males and females before and after renal transplantation

INTRODUCTION

Immunosuppressive drugs taken by transplant recipients may favor HPV infection at anogenital sites. HPV-type prevalence was studied in males and females before and after renal transplantation.

PATIENTS AND METHODS

Anal, cervical and penile samples were taken from 62 patients before transplantation and from 41 patients after transplantation. HPV DNA was investigated using the INNO-LiPA HPV genotyping extra test and HPV-type distribution determined.

RESULTS

Before transplantation, up to 30% of analyzed samples harbored HPV DNA, with the highest prevalence found in cervical specimens (60%). After transplantation, a trend toward HPV clearance was observed in females. By contrast, a trend toward incident infections by a wide variety of HPV genotypes at the penis and anal level was documented in men.

CONCLUSION

High prevalence of HPV at anogenital sites was documented before and after renal transplantation. Immunosuppressive drugs taken after transplantation may impact HPV acquisition or reactivation, especially in males. Special attention should be paid in view of preventing HPV-associated diseases in this vulnerable population.

Safety and efficacy of kidney transplantation in patients with aortoiliac stenosis: a retrospective cohort study

BACKGROUND

The impact of aortoiliac occlusive disease on kidney transplantation remains unclear. This study aims to investigate the clinical outcomes of kidney transplant patients with aortoiliac atherosclerotic stenosis.

METHODS

Retrospective data from our transplant center were used to identify patients undergoing kidney transplantation between January 2010 and December 2020. Aortoiliac atherosclerotic stenosis was screened and stratified by the Trans-Atlantic Inter-Society Consensus (TASC) II classification. The primary outcome was patient survival. Secondary outcomes were 90-day mortality, death-censored graft survival, graft function, and arterial complications. Propensity score matching was used to match all patients in the stenosis group with patients without stenosis sharing similar characteristics.

RESULTS

The analysis included 655 patients, 524 without stenosis and 131 with aortoiliac stenosis (95 with TASC A/B stenosis and 36 with TASC C/D stenosis). Recipient age [median (IQR), 66 (60-70) vs. 66 (59-71) years; P =0.47], sex [male: 87 (66%) vs. 355 (68%), P =0.85], and comorbidities were comparable between the stenosis and no-stenosis groups. Forty-six (35%) patients with stenosis were symptomatic. Patient survival was significantly lower in the stenosis group compared with the no-stenosis group (TASC A/B: 30.6% vs. no-stenosis: 44.1%, P =0.013; TASC C/D: 11.4% vs. no-stenosis: 44.1%, P <0.001). The incidence rates of artery dissection, lower extremity ischemia, and acute thrombosis were significantly higher in the stenosis group ( P <0.001). However, death-censored graft survival (TASC A/B: 73.6% vs. no-stenosis: 72.9%, P =0.62; TASC C/D: 58.1% vs. no-stenosis: 72.9%, P =0.16) and graft function were comparable between the groups.

CONCLUSIONS

Aortoiliac atherosclerotic stenosis significantly impacts patient survival but not graft survival. Our analyses suggest that patients with TASC A/B stenosis have prolonged survival and enhanced quality of life through kidney transplantation. However, for patients with TASC C/D stenosis, kidney transplantation improves quality of life without bringing survival benefits.

Immunological features of ESRD patients undergoing hemodialysis of various ages

AIMS

To investigate the immunological characteristics of hemodialysis (HD) patients with end-stage renal disease (ESRD) of various ages, and the impact of age-related immune alterations on these patients, with a focus on peripheral T cells.

METHODS

From September 2016 to September 2019, HD patients were enrolled and followed prospectively for 3 years. Patients were divided into three groups based on their ages: < 45, 45 to 64, and ≥ 65. The distribution of T cell subsets in different age groups was investigated and compared. The effects of altered T cell subsets on overall survival were also investigated.

RESULTS

A total of 371 HD patients were enrolled. The reduced number of naive CD8+ T cells (P < 0.001) and increased number of EMRA CD8+ T cells (P = 0.024) were independently associated with the advanced age among all T cell subsets studied. Patient survival may be affected by numerical changes in naive CD8+ T cells. However, when HD patients were < 45 or ≥ 65 years, the reduction had no significant impact on survival. Only in HD patients aged 45 to 64 years, the number of naïve CD8+ T cells found to be insufficient but not deficient, identified as an independent predictor of poor survival.

CONCLUSIONS

The most significant age-related immune change in HD patients was a decrease in peripheral naive CD8+ T cells, which was an independent predictor of 3-year overall survival in HD patients aged 45 ~ 64 years.

Gut-immune axis and cardiovascular risk in chronic kidney disease

Patients with chronic kidney disease (CKD) suffer from marked cardiovascular morbidity and mortality, so lowering the cardiovascular risk is paramount to improve quality of life and survival in CKD. Manifold mechanisms are hold accountable for the development of cardiovascular disease (CVD), and recently inflammation arose as novel risk factor significantly contributing to progression of CVD. While the gut microbiome was identified as key regulator of immunity and inflammation in several disease, CKD-related microbiome-immune interaction gains increasing importance. Here, we summarize the latest knowledge on microbiome dysbiosis in CKD, subsequent changes in bacterial and host metabolism and how this drives inflammation and CVD in CKD. Moreover, we outline potential therapeutic targets along the gut-immune-cardiovascular axis that could aid the combat of CVD development and high mortality in CKD.

The Incidence of Antibody-Mediated Rejection Is Age-Related, Plateaus Late After Kidney Transplantation, and Contributes Little to Graft Loss in the Older Recipients

It is not known whether antibody-mediated rejection (ABMR) is age-related, whether it plateaus late after transplantation, and to what extent it contributes to graft loss in older recipients. Patients transplanted between 2010 and 2015 (n = 1,054) in a single center had regular follow-up until January 2023. Recipients were divided into age groups at transplantation: 18-39 years ("young"), 40-55 years ("middle age"), and >55 years ("elderly"). Ten years after transplantation the cumulative % of recipients with ABMR was 17% in young, 15% in middle age, and 12% in elderly recipients (p < 0.001). The cumulative incidence of ABMR increased over time and plateaued 8-10 years after transplantation. In the elderly, with a median follow-up of 7.5 years, on average 30% of the recipients with ABMR died with a functional graft and ABMR contributed only 4% to overall graft loss in this group. These results were cross-validated in a cohort of recipients with >15 years follow-up. Multivariate cox-regression analysis showed that increasing recipient age was independently associated with decreasing risk for ABMR. In conclusion, the cumulative risk for ABMR is age-dependent, plateaus late after transplantation, and contributes little to overall graft loss in older recipients.

Induction of Vesicular Trafficking and JNK-Mediated Apoptotic Signaling in Mononuclear Leukocytes Marks the Immuno-Proteostasis Response to Uremic Proteins

INTRODUCTION

Uremic retention solutes have been alleged to induce the apoptotic program of different cell types, including peripheral blood mononuclear leukocytes (PBL), which may contribute to uremic leukopenia and immune dysfunction.

METHODS

The molecular effects of these solutes were investigated in uremic PBL (u-PBL) and mononuclear cell lines (THP-1 and K562) exposed to the high molecular weight fraction of uremic plasma (u-HMW) prepared by in vitro ultrafiltration with 50 kDa cut-off microconcentrators.

RESULTS

u-PBL show reduced cell viability and increased apoptotic death compared to healthy control PBL (c-PBL). u-HMW induce apoptosis both in u-PBL and c-PBL, as well as in mononuclear cell lines, also stimulating cellular H2O2 formation and secretion, IRE1-α-mediated endoplasmic reticulum stress signaling, and JNK/cJun pathway activation. Also, u-HMW induce autophagy in THP-1 monocytes. u-PBL were characterized by the presence in their cellular proteome of the main proteins and carbonylation targets of u-HMW, namely albumin, transferrin, and fibrinogen, and by the increased expression of receptor for advanced glycation end-products, a scavenger receptor with promiscuous ligand binding properties involved in leukocyte activation and endocytosis.

CONCLUSIONS

Large uremic solutes induce abnormal endocytosis and terminal alteration of cellular proteostasis mechanisms in PBL, including UPR/ER stress response and autophagy, ultimately activating the JNK-mediated apoptotic signaling of these cells. These findings describe the suicidal role of immune cells in facing systemic proteostasis alterations of kidney disease patients, a process that we define as the immuno-proteostasis response of uremia.

Immunosenescence and Immune Exhaustion Are Associated with Levels of Protein-Bound Uremic Toxins in Patients on Hemodialysis

BACKGROUND

The accumulation of protein-bound uremic toxins (PBUTs) in chronic kidney disease may affect patients' immune status. The aim of the study was to evaluate their potential impacts on lymphocyte alterations in patients on hemodialysis (HD).

METHODS

The plasma levels of PBUTs were assessed in 54 patients on HD and 31 healthy individuals, using ultra-performance liquid chromatography. The results correlated with the senescent and exhausted status of lymphocytes, based on certain surface molecules, analyzed by flow cytometry.

RESULTS

The plasma levels of PBUTs were significantly increased in the patients on HD compared with the healthy controls. The patients with residual kidney function had reduced hippuric acid (HA) levels, total (p = 0.03) and free (p = 0.04), and free IxS levels (p = 0.02). The total and free HA levels correlated negatively with less differentiated subpopulations, CD4+CD45RA+CD31+ (p = 0.037 and p = 0.027), CD8+CD28+CD57- (p = 0.01, p = 0.01), and naïve B cells (CD19+IgD+CD27-) (p = 0.04, p = 0.03). Both the total and the free pCS levels correlated positively with exhausted CD4 cells, p = 0.02 and p = 0.01, respectively. A multivariate analysis showed that IxS and age were the main independent parameters implicated in the reduction intotal CD4 and B lymphocytes and their naïve and early differentiated subsets.

CONCLUSIONS

Increased PBUTs levels are associated with immune disturbances of patients on HD, HA, and IxS in the immunosenescent and pCS in the immunoexhaustion alterations.

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.

Lowering maintenance immune suppression in elderly kidney transplant recipients; connecting the immunological and clinical dots

The management of long-term immune suppressive medication in kidney transplant recipients is a poorly explored field in the area of transplant medicine. In particular, older recipients are at an increased risk for side effects and have an exponentially increased risk of infection-related death. In contrast, an aged immune system decreases the risk of acute T-cell-mediated rejection in older recipients. Recent advances in alloimmunity research have shown a rapid and substantial decline in polyfunctional, high-risk CD4⁺ T cells post-transplantation. This lowers the direct alloreactivity responsible for T-cell-mediated rejection, also known as donor-specific hyporesponsiveness. Chronic antibody-mediated rejection (c-aABMR) is the most frequent cause of kidney graft loss in the long term. However, in older adults, c-aABMR as a cause of graft loss is outnumbered by death with a functioning graft. In addition, DSA development and a diagnosis of c-aABMR plateau ~10 years after transplantation, resulting in a very low risk for rejection thereafter. The intensity of immune suppression regimes could likely be reduced accordingly, but trials in this area are scarce. Tacrolimus monotherapy for 1 year after transplantation seems feasible in older kidney transplant recipients with standard immunological risk, showing the expected benefits of fewer infections and better vaccination responses.

Exhaustion of CD8+ central memory responder T cell differentiation provokes non-melanoma skin cancer in elderly kidney transplant recipients

Introduction

Immunosuppressive therapy prevents graft rejection but increases the risk of non-melanoma skin cancer (NMSC), especially in elderly kidney transplant recipients (KTR).

Methods

In this study, we separately investigated the differentiation of CD8⁺ regulatory T cells (Tregs) and responder T cells (Tresps) between healthy KTR without NMSC, KTR developing de-novo NMSC within two years after the enrolment, and KTR with NMSC at the time of enrolment. Antigen-unexperienced CCR7⁺CD45RA⁺CD31⁺ recent thymic emigrant (RTE) cells differentiate via CD45RA^-CD31⁺ memory (CD31⁺ memory) cells, via resting mature naïve (MN) cells or via direct proliferation into CD45RA^-CD31^- memory (CD31^- memory) cells, consisting of both CCR7⁺CD45RA^- central memory (CM) and CCR7^-CD45RA^- effector memory (EM) cells.

Results

We found that both RTE Treg and Tresp differentiation via CD31⁺ memory Tregs/Tresps was age-independently increased in KTR, who developed de novo NMSC during the follow-up period, causing abundant CM Treg/Tresp production, which may be crucial for cancer immunity. These changes favored a strongly increased CD8⁺ Treg/Tresp ratio, suggesting this ratio as a reliable marker for de-novo NMSC development in KTR. However, with age, this differentiation was replaced by increased conversion of resting MN Tregs/Tresps into CM Tregs/Tresps, which exhausted for Tresps but not for Tregs. In KTR with already existing NMSC at enrolment, differentiation was maintained via conversion and proliferation of resting MN Tregs/Tresps, which however increasingly exhausted with age, especially for Tresps. This resulted in a strong accumulation of terminally differentiated effector memory (TEMRA) Tresps in elderly individuals. Patients with NMSC recurrence showed increased proliferation of resting MN Tregs/Tresps into EM Tregs/Tresps, which tended to exhaust more rapidly, particularly for Tresps, than in patients without NMSC recurrence.

Discussion

In conclusion, we provide evidence that immunosuppressive therapy inhibits differentiation of CD8⁺ Tregs more than that of CD8⁺ Tresps, resulting in an exhausted Tresp profile, thus providing a possible therapeutic approach to improve poor cancer immunity in elderly KTR.

Differential Methylation of Telomere-Related Genes Is Associated with Kidney Disease in Individuals with Type 1 Diabetes

Diabetic kidney disease (DKD) represents a major global health problem. Accelerated ageing is a key feature of DKD and, therefore, characteristics of accelerated ageing may provide useful biomarkers or therapeutic targets. Harnessing multi-omics, features affecting telomere biology and any associated methylome dysregulation in DKD were explored. Genotype data for nuclear genome polymorphisms in telomere-related genes were extracted from genome-wide case-control association data (n = 823 DKD/903 controls; n = 247 end-stage kidney disease (ESKD)/1479 controls). Telomere length was established using quantitative polymerase chain reaction. Quantitative methylation values for 1091 CpG sites in telomere-related genes were extracted from epigenome-wide case-control association data (n = 150 DKD/100 controls). Telomere length was significantly shorter in older age groups (p = 7.6 × 10^-6). Telomere length was also significantly reduced (p = 6.6 × 10^-5) in DKD versus control individuals, with significance remaining after covariate adjustment (p = 0.028). DKD and ESKD were nominally associated with telomere-related genetic variation, with Mendelian randomisation highlighting no significant association between genetically predicted telomere length and kidney disease. A total of 496 CpG sites in 212 genes reached epigenome-wide significance (p ≤ 10^-8) for DKD association, and 412 CpG sites in 193 genes for ESKD. Functional prediction revealed differentially methylated genes were enriched for Wnt signalling involvement. Harnessing previously published RNA-sequencing datasets, potential targets where epigenetic dysregulation may result in altered gene expression were revealed, useful as potential diagnostic and therapeutic targets for intervention.

Impact of Single Hemodialysis Treatment on immune Cell Subpopulations

Hemodialysis (HD) is known to trigger a chronic inflammatory status, affecting the innate and acquired immune response. This study was aimed at a comparative analysis of immune cell subsets, proliferation, and apoptosis in subjects receiving chronic HD treatment with respect to a healthy control. Regardless of the dialysis filter used, we observed a reshaping of the acquired immune component both with respect to healthy patients and between the various sessions of dialysis treatment, with an impairment of CD3 cells, along with an increase in CD4 and CD8 cell populations producing pro-inflammatory factors such as IL-17 and IFN-gamma. The population of B cells, monocytes and NK cells were not impaired by the dialysis procedure. These results confirmed the high impact of the HD treatment on the patient's immune system, underlying the imbalance of T cell counterparts.

Harnessing Genomic Analysis to Explore the Role of Telomeres in the Pathogenesis and Progression of Diabetic Kidney Disease

The prevalence of diabetes is increasing globally, and this trend is predicted to continue for future decades. Research is needed to uncover new ways to manage diabetes and its co-morbidities. A significant secondary complication of diabetes is kidney disease, which can ultimately result in the need for renal replacement therapy, via dialysis or transplantation. Diabetic kidney disease presents a substantial burden to patients, their families and global healthcare services. This review highlights studies that have harnessed genomic, epigenomic and functional prediction tools to uncover novel genes and pathways associated with DKD that are useful for the identification of therapeutic targets or novel biomarkers for risk stratification. Telomere length regulation is a specific pathway gaining attention recently because of its association with DKD. Researchers are employing both observational and genetics-based studies to identify telomere-related genes associated with kidney function decline in diabetes. Studies have also uncovered novel functions for telomere-related genes beyond the immediate regulation of telomere length, such as transcriptional regulation and inflammation. This review summarises studies that have revealed the potential to harness therapeutics that modulate telomere length, or the associated epigenetic modifications, for the treatment of DKD, to potentially slow renal function decline and reduce the global burden of this disease.

Telomere Attrition in Chronic Kidney Diseases

Telomeres are dynamic DNA nucleoprotein structures located at the end of chromosomes where they maintain genomic stability. Due to the end replication problem, telomeres shorten with each cell division. Critically short telomeres trigger cellular senescence, which contributes to various degenerative and age-related diseases, including chronic kidney diseases (CKDs). Additionally, other factors such as oxidative stress may also contribute to accelerated telomere shortening. Indeed, telomeres are highly susceptible to oxidative damage due to their high guanine content. Here, we provide a comprehensive review of studies examining telomere length (TL) in CKDs to highlight the association between TL and the development and progression of CKDs in humans. We then focus on studies investigating TL in patients receiving kidney replacement therapy. The mechanisms of the relationship between TL and CKD are not fully understood, but a shorter TL has been associated with decreased kidney function and the progression of nephropathy. Interestingly, telomere lengthening has been observed in some patients in longitudinal studies. Hemodialysis has been shown to accelerate telomere erosion, whereas the uremic milieu is not reversed even in kidney transplantation patients. Overall, this review aims to provide insights into the biological significance of telomere attrition in the pathophysiology of kidney disease, which may contribute to the development of new strategies for the management of patients with CKDs.

Decreased thymic output predicts progression of chronic kidney disease

BACKGROUND

Chronic kidney disease (CKD) is age-related disease, and decreased renal function is associated with the premature aging of T cells and increased incidence of other age-related diseases. However, the relationship between T cell senescence and CKD progression remains unclear. Here, we investigated the relationship between T cell senescence, as indicated by decreased thymic output and increased proportion of highly differentiated CD28^- T cells, and CKD progression.

RESULTS

A total of 175 patients with non-dialysis-dependent CKD were enrolled in this study. Thymic output was assessed based on the CD45RA⁺CD31⁺CD4⁺ cell (recent thymic emigrant [RTE]) counts (RTEs) (/mm³) and the proportion of RTE among CD4⁺ T cells (RTE%). Highly differentiated T cells were assessed based on the proportion of CD28^- cells among CD4⁺ T cells (CD28^-/CD4⁺) and CD28^- cells among CD8⁺ T cells (CD28^-/CD8⁺). The primary outcome was estimated glomerular filtration rate (eGFR) decline of ≥40% or initiation of renal replacement therapy. The association between T cell senescence and renal outcomes was examined using Cox proportional hazards models and restricted cubic splines. The median age was 73 years, 33% were women, and the median eGFR was 26 mL/min/1.73 m². The median RTEs, RTE%, CD28^-/CD4⁺, and CD28^-/CD8⁺ were 97.5/mm³, 16.2, 5.3, and 49.7%, respectively. After a median follow-up of 1.78 years, renal outcomes were observed in 71 patients. After adjusting for age, sex, eGFR, proteinuria, diabetes, and cytomegalovirus seropositivity, decreased RTEs, which corresponded to decreased thymic output, significantly and monotonically increased the risk of poor renal outcome (p = 0.04), and decreased RTE% and increased highly differentiated CD28^-/CD4⁺ T cells also tended to monotonically increase the risk (p = 0.074 and p = 0.056, respectively), but not CD28^-/CD8⁺ T cells.

CONCLUSIONS

Decreased thymic output in CKD patients, as well as increased highly differentiated CD4⁺ T cells, predicted renal outcomes. Thus, the identification of patients prone to CKD progression using T cell senescence, particularly decreased RTE as a biomarker, may help to prevent progression to end-stage kidney disease.

Dysbiosis of Gut Microbiota Contributes to Uremic Cardiomyopathy via Induction of IFNγ-Producing CD4+ T Cells Expansion

Uremic cardiomyopathy (UCM) correlates with chronic kidney disease (CKD)-induced morbidity and mortality. Gut microbiota has been involved in the pathogenesis of certain cardiovascular disease, but the role of gut microbiota in the pathogenesis of UCM remains unknown. Here, we performed a case-control study to compare the gut microbiota of patients with CKD and healthy controls by 16S rRNA (rRNA) gene sequencing. To test the causative relationship between gut microbiota and UCM, we performed fecal microbiota transplantation (FMT) in 5/6th nephrectomy model of CKD. We found that opportunistic pathogens, particularly Klebsiella pneumoniae (K. pneumoniae), are markedly enriched in patients with CKD. FMT from CKD patients aggravated diastolic dysfunction in the mouse model. The diastolic dysfunction was associated with microbiome-dependent increases in heart-infiltrating IFNγ+ CD4+ T cells. Monocolonization with K. pneumoniae increased cardiac IFNγ+ CD4+ T cells infiltration and promoted UCM development of the mouse model. A probiotic Bifidobacterium animalis decreased the relative abundance of K. pneumoniae, reduced levels of cardiac IFNγ+ CD4+ T cells and ameliorated the severity of diastolic dysfunction in the mice. Thus, the aberrant gut microbiota in CKD patients, especially K. pneumoniae, contributed to UCM pathogenesis through the induction of heart-infiltrating IFNγ+ CD4+ T cells expansion, proposing that a Gut Microbiota-Gut-Kidney-Heart axis could play a critical role in elucidating the etiology of UCM, and suggesting that modulation of the gut bacteria may serve as a promising target for the amelioration of UCM. IMPORTANCE Uremic cardiomyopathy (UCM) correlates tightly with increased mortality in patients with chronic kidney disease (CKD), yet the pathogenesis of UCM remains incompletely understood, limiting therapeutic approaches. Our study proposed that a Gut Microbiota-Gut-Kidney-Heart axis could play a critical role in understanding etiology of UCM. There is a major need in future clinical trials of patients with CKD to explore if modulation of gut microbiota by fecal microbiota transplantation (FMT), probiotics or antibiotics can alleviate cardiac dysfunction, reduce mortality, and improve life quality.

Hemodialysis-Associated Immune Dysregulation in SARS-CoV-2-Infected End-Stage Renal Disease Patients

Patients on hemodialysis show dysregulated immunity, basal hyperinflammation and a marked vulnerability to COVID-19. We evaluated the immune profile in COVID-19 hemodialysis patients and the changes associated with clinical deterioration after the hemodialysis session. Recruited patients included eight hemodialysis subjects with active, PCR-confirmed SARS-CoV-2 infection, five uninfected hemodialysis patients and five healthy controls. In SARS-CoV-2-infected hemodialysis patients TNF-α, IL-6 and IL-8 were particularly increased. Lymphopenia was mostly due to reduction in CD4+ T, B and central memory CD8+ T cells. There was a predominance of classical and intermediate monocytes with reduced HLA-DR expression and enhanced production of pro-inflammatory molecules. Immune parameters were analysed pre- and post-hemodialysis in three patients with COVID-19 symptoms worsening after the hemodialysis session. There was a higher than 2.5-fold increase in GM-CSF, IFN-γ, IL-1β, IL-2, IL-6, IL-17A and IL-21 in serum, and augmentation of monocytes-derived TNF-α, IL-1β and IL-8 and CXCL10 (p < 0.05). In conclusion, COVID-19 in hemodialysis patients associates with alteration of lymphocyte subsets, increasing of pro-inflammatory cytokines and monocyte activation. The observed worsening during the hemodialysis session in some patients was accompanied by augmentation of particular inflammatory cytokines, which might suggest biomarkers and therapeutic targets to prevent or mitigate the hemodialysis-related deterioration during SARS-CoV-2 infection.

Characterization of regulatory T cells in SARS-CoV-2 infected hemodialysis patients: relation to clinical and radiological severity

BACKGROUND

Disordered Treg counts and function have been observed in patients with SARS-Cov-2 and are thought to contribute to disease severity. In hemodialysis patients, scarce data are available on the Treg response to SARS-CoV-2 or its relation to the clinical presentation.

METHODS

A cross-sectional study included one hundred patients divided into three groups, thirty SARS-CoV-2-infected hemodialysis patients (COV-HD), and thirty confirmed SARSCoV-2 infected patients (COV), and forty non-infected hemodialysis patients (HD). Flow cytometric analysis of CD4, CD25, FoxP3, and CD39+ Tregs was done for all patients and tested for correlation to in-hospital mortality, clinical, radiological severity indices.

RESULTS

COV-HD and COV patients had significantly lower Treg cell count than HD patients (Median value of 0.016 cell/ μl vs 0.28 cell/ μl, respectively- P: 0.001). COV-HD patients had higher CD39+ Tregs (median value of 0.006 cell/ μl vs 0.002 cell/ μl, respectively- P: 0.04). COV-HD patients had significantly lower hospital stay (median value of 3 vs 13 days, P:0.001), ICU admission rates (26.5% vs 46.7%, P:0.005) and in-hospital mortality (20.7% versus 43.3%, P:0.003) than COV patients. Treg and CD39 expressing Treg counts were not correlated to severity indices in both groups. A high neutrophil to lymphocyte ratio is strongly correlated to disease severity in COV-HD patients.

CONCLUSIONS

This study provides evidence of T-cell, particularly T-regulatory cell decline in SARS-CoV-2 and suggests that hemodialysis per se does not distinctively impact the T-cell response. COV-HD patients exhibited a higher CD39+ Treg count and a better clinical profile, however, larger studies are needed to extrapolate on these findings.

Different Types of Chronic Inflammation Engender Distinctive Immunosenescent Profiles in Affected Patients

Immunosenescence encompasses a spectrum of lymphocyte phenotypic alterations. The aim of the study was to evaluate immunosenescent effect of two different forms of chronic inflammation, Systemic Lupus Erythematosous (SLE), a systemic autoimmune disease, and End-Stage Kidney Disease (ESKD), a chronic inflammatory disorder. Certain lymphocyte surface molecules, including CD31, CD45RA, CCR7, CD28, CD57, for T, and IgD, CD27 for B lymphocytes, were analyzed by flow cytometry in 30 SLE and 53 ESKD patients on hemodialysis (HD), and results were compared to 31 healthy controls (HC) of similar age, gender, and nationality. Significant Lymphopenia was evident in both SLE and ESKD-HD patients, compared to HC, affecting B cells 75.4 (14.4−520.8), 97 (32−341), and 214 (84−576) cells/μL, respectively, p < 0.0001, and CD4 cells 651.2 (71.1−1478.2), 713 (234−1509), and 986 (344−1591) cells/μL, respectively, p < 0.0001. The allocation of B cell subpopulations was remarkably different between SLE and ESKD-HD patients. SLE showed a clear shift to senescence (CD19IgD-CD27−) cells, compared to ESKD-HD and HC, 11.75 (10)% vs. 8 (6) vs. 8.1 (10), respectively. Regarding T lymphocytes, Central Memory CD8 cells predominated in both SLE and ESKD-HD patients compared to HC, 53 (50)%, 52 (63), and 24 (64)%, respectively, while ESKD-HD but not SLE patients also had increased expression of CD4CD28− and CD8CD28− cells. In conclusion, both diseases are followed by significant lymphopenia; however, the senescent phenomenon affects the B lymphocyte compartment in SLE patients and T lymphocytes in ESKD-HD patients.

The diseased kidney: aging and senescent immunology

Immunosenescence is the deterioration of the innate and adaptive immune systems associated with aging and is primarily characterized by a reduction in T cell production and accumulation of atypical subsets. Age-related immunological dysfunction leads to impaired immune protection and persistent low-grade chronic inflammation, resulting in a decreased vaccination response and increased vulnerability to infection, cancer, cardiovascular disease, and autoimmune disease in the elderly. As the elderly constitute a growing proportion of the population with renal disease, immunosenescence is a normal aging process that is prevalent among older people. In addition, immunosenescence seems to be more pronounced in patients with kidney diseases than in healthy controls, as shown by severe chronic inflammation, accumulation of immune cells with the senescent phenotype (CD28− T cells, CD14+CD16+ monocytes), and proinflammatory cytokine production. Immunosenescence inhibits immunological clearance and renal tissue regeneration, thereby increasing the risk of permanent renal damage, infection, and cardiovascular events in patients with kidney disease, lowering the prognosis, and even influencing the efficacy of renal replacement treatment. Biological drugs (senomorphics and senolytics) target the aging immune system and exert renoprotective effects. This review aims to emphasize the features of immunosenescence and its influence on kidney diseases and immunotherapy, highlighting the future directions of kidney disease treatment using senescence-focused techniques.

Vaccination in patients with kidney failure: lessons from COVID-19

Infection is the second leading cause of death in patients with chronic kidney disease (CKD). Adequate humoral (antibody) and cellular (T cell-driven) immunity are required to minimize pathogen entry and promote pathogen clearance to enable infection control. Vaccination can generate cellular and humoral immunity against specific pathogens and is used to prevent many life-threatening infectious diseases. However, vaccination efficacy is diminished in patients with CKD. Premature ageing of the immune system and chronic systemic low-grade inflammation are the main causes of immune alteration in these patients. In the case of SARS-CoV-2 infection, COVID-19 can have considerable detrimental effects in patients with CKD, especially in those with kidney failure. COVID-19 prevention through successful vaccination is therefore paramount in this vulnerable population. Although patients receiving dialysis have seroconversion rates comparable to those of patients with normal kidney function, most kidney transplant recipients could not generate humoral immunity after two doses of the COVID-19 vaccine. Importantly, some patients who were not able to produce antibodies still had a detectable vaccine-specific T cell response, which might be sufficient to prevent severe COVID-19. Correlates of protection against SARS-CoV-2 have not been established for patients with kidney failure, but they are urgently needed to enable personalized vaccination regimens.

Telomere therapy for chronic kidney disease

Chronic kidney disease (CKD) is estimated to affect almost 10% of individuals worldwide and is one of the leading causes of morbidity and mortality. Renal fibrosis, a central pathway in CKD progression (irrespective of etiology), is associated with shortened or dysfunctional telomeres in animal studies. Telomeres are specialized nucleoprotein structures located at the chromosome end that maintain genomic integrity. The mechanisms of associations between telomere length and CKD have not yet been fully elucidated, however, CKD patients with shorter telomere length may have decreased renal function and a higher mortality rate. A plethora of ongoing research has focused on possible therapeutic applications of telomeres with the overall goal to preserve telomere length as a therapy to treat CKD.

Boosting the VZV-Specific Memory B and T Cell Response to Prevent Herpes Zoster After Kidney Transplantation

Background

Solid organ transplant recipients are at high risk to develop (complicated) herpes zoster (HZ). Booster vaccination could prevent HZ. However, end-stage renal disease (ESRD) patients show poor immunological responses to vaccinations. We studied the effect of a live attenuated VZV booster vaccine on VZV-specific B and T cell memory responses in ESRD patients and healthy controls. NL28557.000.09, www.toetsingonline.nl

Methods

VZV-seropositive patients, aged ≥50 years, awaiting kidney transplantation, were vaccinated with Zostavax^®. Gender and age-matched VZV-seropositive potential living kidney donors were included as controls. VZV-specific IgG titers were measured before, at 1, 3 and 12 months post-vaccination. VZV-specific B and T cell responses before, at 3 months and 1 year after vaccination were analysed by flow-cytometry and Elispot, respectively. Occurrence of HZ was assessed at 5 years post-vaccination.

Results

26 patients and 27 donors were included. Median VZV-specific IgG titers were significantly higher at all time-points post-vaccination in patients (mo 1: 3104 IU/ml [1967-3825], p<0.0001; mo 3: 2659 [1615-3156], p=0.0002; mo 12: 1988 [1104-2989], p=0.01 vs. pre: 1397 [613-2248]) and in donors (mo 1: 2981 [2126-3827], p<0.0001; mo 3: 2442 [2014-3311], p<0.0001; mo 12: 1788 [1368-2460], p=0.0005 vs. pre: 1034 [901-1744]. The patients’ IgG titers were comparable to the donors’ at all time-points. The ratio VZV-specific B cells of total IgG producing memory B cells had increased 3 months post-vaccination in patients (0.85 [0.65-1.34] vs. pre: 0.56 [0.35-0.81], p=0.003) and donors (0.85 [0.63-1.06] vs. pre: 0.53 [0.36-0.79], p<0.0001) and remained stable thereafter in donors. One year post-vaccination, the percentage of CD4+ central memory cells had increased in both patients (0.29 [0.08-0.38] vs. 0.12 [0.05-0.29], p=0.005) and donors (0.12 [0.03-0.37] vs. 0.09 [0.01-0.20], p=0.002) and CD4+ effector memory cells had increased in donors (0.07 [0.02-0.14] vs. 0.04 [0.01-0.12], p=0.007). Only 1 patient experienced HZ, which was non-complicated.

Conclusion

VZV booster vaccination increases VZV-specific IgG titers and percentage VZV-specific memory T-cells for at least 1 year both in ESRD patients and healthy controls. VZV-specific memory B cells significantly increased in patients up to 3 months after vaccination. Prophylactic VZV booster vaccination prior to transplantation could reduce HZ incidence and severity after transplantation.

Immunosenescence: A Critical Factor Associated With Organ Injury After Sepsis

Progressive immune dysfunction associated with aging is known as immunosenescence. The age-related deterioration of immune function is accompanied by chronic inflammation and microenvironment changes. Immunosenescence can affect both innate and acquired immunity. Sepsis is a systemic inflammatory response that affects parenchymal organs, such as the respiratory system, cardiovascular system, liver, urinary system, and central nervous system, according to the sequential organ failure assessment (SOFA). The initial immune response is characterized by an excess release of inflammatory factors, followed by persistent immune paralysis. Moreover, immunosenescence was found to complement the severity of the immune disorder following sepsis. Furthermore, the immune characteristics associated with sepsis include lymphocytopenia, thymus degeneration, and immunosuppressive cell proliferation, which are very similar to the characteristics of immunosenescence. Therefore, an in-depth understanding of immunosenescence after sepsis and its subsequent effects on the organs may contribute to the development of promising therapeutic strategies. This paper focuses on the characteristics of immunosenescence after sepsis and rigorously analyzes the possible underlying mechanism of action. Based on several recent studies, we summarized the relationship between immunosenescence and sepsis-related organs. We believe that the association between immunosenescence and parenchymal organs might be able to explain the delayed consequences associated with sepsis.

A Novel Technique for the Generation of Substantial Numbers of Functional Resident T Cells from Kidney Tissue

Studying functionality and antigen-specificity of resident kidney T cells derived from a kidney biopsy is hampered by the lack of sufficient numbers of T cells obtained by the standard method of enzymatic tissue dissociation. Enzymatic dissociation of kidney tissue was compared to a novel method of whole kidney tissue culture allowing T cells to migrate into the medium in the presence of exogenous IL-2 and IL-15. T cell numbers were quantified and phenotype of resident T cells (CD69+CD103+/−), TCR Vβ repertoire and functional characteristics were analyzed with multi-parameter flow cytometry. Renal tissue culture for four weeks in the presence of exogenous IL-2 and IL-15 yielded significantly higher numbers of T cells (1.3 × 104/mm3) when compared to cultures without exogenous cytokines (71/mm3) or direct isolation by enzymatic dissociation (662/mm3 T cells, p < 0.05). The proportion of T cells with a resident phenotype did not change in the tissue culture; percentages amounted to 87.2% and 85.1%, respectively. In addition, frequencies of CD4+, CD8+, CD4−CD8−, T cells and MAIT T cells remained similar. For both CD4+ and CD8+, T cells had a more differentiated memory phenotype after tissue culture, but the distribution of TCR Vβ families did not change. In addition, the predominant Th1 cytokine secretion profile and poly-functionality of resident kidney T cell remained intact. T cell proliferation potential was not affected, excluding exhaustion and enrichment of BKV- and CMV-reactive resident T cells was observed. In conclusion, the kidney tissue culture method yields significantly increased numbers of resident T cells without major effects on composition and functionality.

Chronic Kidney Failure Provokes the Enrichment of Terminally Differentiated CD8+ T Cells, Impairing Cytotoxic Mechanisms After Kidney Transplantation

Chronic kidney failure (KF) provokes the development of immune senescent CD8⁺ cytotoxic T cells, affecting the occurrence of graft rejection, viral infections, and malignancies after kidney transplantation. In this study, we analyzed the impact of KF, subsequent dialysis treatment, and kidney transplantation on the differentiation of CD8⁺CD31⁺CD45RA⁺CCR7⁺ recent thymic emigrant (CCR7⁺ RTE) Tregs/Tresps into CD8⁺CD31^-CD45RA^- memory (CD31^- memory) Tregs/Tresps and its effect on the release of cytokines, Fas receptor, Fas ligand as well as cytotoxic mediators by naïve, central memory (CM), effector memory (EM), and terminally differentiated effector memory (TEMRA) Tresps. We found that normal age-dependent differentiation of CD8⁺ Tregs/Tresps generally differs in the way that TEMRA cells only arise in Tresps. Compared to healthy controls, KF patients revealed an age-independently decreased frequency of CCR7⁺ RTE Tregs/Tresps, but increased frequencies of CCR7⁺ MN Tregs/Tresps and CD31^- memory Tregs/Tresps, suggesting an increased differentiation via CD31⁺CD45RA^- memory (CD31⁺ memory) Tregs/Tresps into CD31^- memory Tregs/Tresps. Intensified differentiation via CD31⁺ memory Tresps increased the emergence of apoptosis-resistant CM Tresps with strong Fas ligand-mediated cytotoxicity. CCR7⁺ RTE Tresp proliferation generated TEMRA Tresps, secreting high levels of cytotoxic mediators. In dialysis and transplant patients, CD31⁺ TEMRA Tregs/Tresps accumulated, proposing an impaired CCR7⁺ RTE Treg/Tresp differentiation via CD31⁺ memory Tregs/Tresps into CD31^- memory Tregs/Tresps. Increased percentages of CD31^- TEMRA Tresps, but not of CD31^- TEMRA Tregs, were observed in all patient groups, indicating impaired proliferation of CCR7⁺ RTE Tresps, but not of CCR7⁺ RTE Tregs, into CD31^- memory Tregs/Tresps. In transplant patients, CCR7⁺ RTE Tregs accumulated, while frequencies of CCR7⁺ RTE Tresps were decreased, suggesting that the immunosuppressive therapy only prevented excessive CCR7⁺ RTE Treg differentiation but not that of CCR7⁺ RTE Tresps. Presumably, this caused the accumulation of TEMRA Tresps with decreased release of cytotoxic mediators, such as perforin. In conclusion, we propose that chronic KF affects both the differentiation of CD8⁺ Tregs and CD8⁺ Tresps. However, the immunosuppressive therapy after transplantation may successfully prevent excessive Treg differentiation, but not as suffciently that of Tresps. Therefore, the risk for graft rejection may be reduced, while the susceptibility for infections and malignancies may be increased in these patients.

Clustering of End Stage Renal Disease Patients by Dimensionality Reduction Algorithms According to Lymphocyte Senescence Markers

End stage renal disease (ESRD) engenders detrimental effects in the Immune system, manifested as quantitative alterations of lymphocyte subpopulations, akin, albeit not identical to those observed during the ageing process. We performed dimensionality reduction of an extended lymphocyte phenotype panel of senescent and exhaustion related markers in ESRD patients and controls with Principal Component Analysis (PCA) and Uniform Manifold Approximation and Projection (UMAP). The plane defined by the first two principal components of PCA showed two fuzzy clusters, for patients and controls, respectively, with loadings of non-senescent markers pointing towards the controls’ centroid. Naive lymphocytes were reduced in ESRD patients compared to controls (CD4+CD45RA+CCR7+ 200(150-328) vs. 426(260-585cells/μl respectively, P = 0.001, CD19+IgD+CD27- 54(26-85) vs. 130(83-262)cells/μl respectively, P < 0.001). PCA projections of the multidimensional ESRD immune phenotype suggested a more senescent phenotype in hemodialysis compared to hemodiafiltration treated patients. Lastly, clustering based on UMAP revealed three distinct patient groups, exhibiting gradual changes for naive, senescent, and exhausted lymphocyte markers. Machine learning algorithms can distinguish ESRD patients from controls, based on their immune-phenotypes and also, unveil distinct immunological groups within patients’ cohort, determined possibly by dialysis prescription.

Chronic Inflammation Might Protect Hemodialysis Patients From Severe COVID-19

Hemodialysis patients (HD) are expected to have excess mortality in coronavirus disease 2019 (COVID-19). This was challenged by a recent study reporting HD patients to have comparable mortality and less ICU admissions when hospitalized with COVID-19. An altered immune system due to chronic inflammation might protect HD-patients from severe COVID-19. Therefore, we aimed to describe the peripheral blood immune phenotype in HD-patients and respective controls with COVID-19.

Relative leucocyte telomere length is associated with incident end-stage kidney disease and rapid decline of kidney function in type 2 diabetes: analysis from the Hong Kong Diabetes Register

AIMS/HYPOTHESIS

Few large-scale prospective studies have investigated associations between relative leucocyte telomere length (rLTL) and kidney dysfunction in individuals with type 2 diabetes. We examined relationships between rLTL and incident end-stage kidney disease (ESKD) and the slope of eGFR decline in Chinese individuals with type 2 diabetes.

METHODS

We studied 4085 Chinese individuals with type 2 diabetes observed between 1995 and 2007 in the Hong Kong Diabetes Register with stored baseline DNA and available follow-up data. rLTL was measured using quantitative PCR. ESKD was diagnosed based on the ICD-9 code and eGFR.

RESULTS

In this cohort (mean ± SD age 54.3 ± 12.6 years) followed up for 14.1 ± 5.3 years, 564 individuals developed incident ESKD and had shorter rLTL at baseline (4.2 ± 1.2 vs 4.7 ± 1.2, p < 0.001) than the non-progressors (n = 3521). On Cox regression analysis, each ∆∆Ct decrease in rLTL was associated with an increased risk of incident ESKD (HR 1.21 [95% CI 1.13, 1.30], p < 0.001); the association remained significant after adjusting for baseline age, sex, HbA1c, lipids, renal function and other risk factors (HR 1.11 [95% CI 1.03, 1.19], p = 0.007). Shorter rLTL at baseline was associated with rapid decline in eGFR (>4% per year) during follow-up (unadjusted OR 1.22 [95% CI 1.15, 1.30], p < 0.001; adjusted OR 1.09 [95% CI 1.01, 1.17], p = 0.024).

CONCLUSIONS/INTERPRETATION

rLTL is independently associated with incident ESKD and rapid eGFR loss in individuals with type 2 diabetes. Telomere length may be a useful biomarker for the progression of kidney function and ESKD in type 2 diabetes.

SARS-CoV-2 infection in dialysis and kidney transplant patients: immunological and serological response

Background

Dialysis and kidney transplant patients with moderate-severe COVID-19 have a high mortality rate, around 30%, that is similar in the two populations, despite differences in their baseline characteristics. In these groups, the immunology of the disease has been poorly explored.

Methods

Thirty-two patients on dialysis or with kidney transplant and SARS-CoV-2 infection requiring hospitalization (COV group) were included in our study. Lymphocyte subsets, dendritic cell (DC) counts and monocyte activation were studied. SARS-CoV-2 anti-spike/anti-nucleocapsid were monitored, and baseline cytokines and chemokines were measured in 10 patients.

Results

The COV group, compared to healthy subjects and uninfected dialysis/kidney transplant controls, showed lower numbers of CD4 + and CD8 + T cells, Natural-Killer (NK), B cells, plasmacytoid and myeloid DCs, while the proportion of terminally differentiated B-cells was increased. IL6, IL10, IFN-α and chemokines involved in monocyte and neutrophil recruitment were higher in the COV group, compared to uninfected dialysis/kidney transplant controls.

Patients with severe disease had lower CD4 + , CD8 + and B-cell counts and lower monocyte HLA-DR expression. Of note, when comparing dialysis and kidney transplant patients with COVID-19, the latter group presented lower NK and pDC counts and monocyte HLA-DR expression. Up to 60 days after symptom onset, kidney transplant recipients showed lower levels of anti-spike antibodies compared to dialysis patients.

Conclusions

During SARS-CoV-2 infection, dialysis and kidney transplant patients manifest immunophenotype abnormalities; these are similar in the two groups, however kidney transplant recipients show more profound alterations of the innate immune system and lower anti-spike antibody response.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s40620-021-01214-8.

Expression of Ferroptosis-Related Genes is Correlated with Immune Microenvironment in Diabetic Kidney Disease

OBJECTIVE

This study aims to explore the correlation between ferroptosis and immune microenvironment (IME) in diabetic kidney disease (DKD) to provide a new clue for exploring the underlying molecular mechanisms.

METHODS

Corresponding RNA data of DKD patients were downloaded from GEO databases. The weighted gene co-expression network analysis (WGCNA) was used to construct the network, and the selected hub genes, then, overlapped with ferroptosis-related genes (FRGs) from FerrDb. Consensus clustering was performed to identify new molecular subgroups. ESTIMATE, TIMER and ssGSEA analyses were applied to determinate the IME and immune status. Functional analyses including GO, KEGG and GSEA were conducted to elucidate the underlying mechanisms.

RESULTS

Two molecular subtypes were identified based on the expression of FRGs. ESTIMATE algorithm revealed that there were significant differences in ESTIMATE score between these two clusters of DKD patients, with no significant difference found in stromal score and immune score. In addition, TIMER algorithm indicated there was a significant difference in the degree of T cell infiltration. The ssGSEA algorithm showed immunity was mainly concentrated in thick ascending limb and distal convoluted tubule in adult kidney. GO, KEGG and GSEA analyses revealed that the differentially expressed genes (DEGs) were mainly enriched in immune and metabolism associated pathways.

CONCLUSION

The ferroptosis may be induced by dysregulation of IME, thereby accelerating the progression of DKD. Our work could be applied to provide a new clue for exploring the underlying molecular mechanisms and sheds novel light on the therapy strategy of DKD.

T cell subpopulations and cytokine levels in hemodialysis patients

HD patients have impaired adaptive immune responses, which might depend on the primary cause of chronic kidney disease (CKD). We analyzed percentages of T cells subpopulations with the expression of CD69, CD25, CD95, and HLA-DR antigens in HD patients to determine the status of T cell activation. Also, we determined serum levels of cytokines: IL12p70, TNF, IL-10, IL-6, IL-1β, IL-8. HD patients had increased percentages of CD4⁺CD25⁺, CD4⁺CD69⁺, CD4⁺HLA-DR⁺, CD8⁺CD69⁺, and CD8⁺HLA-DR⁺ cells compared to healthy people. Also, their IL-6 and IL-8 serum levels were higher. Changes in T cell subpopulations were seen in patients with diabetic nephropathy (DN) or ischemic nephropathy (IN) but not with glomerulonephritis (GN). HD patients dialyzed for more than six months had a lower percentage of CD4⁺CD69⁺, CD8⁺HLA-DR⁺, CD8⁺CD95⁺ cells, higher IL-12p70 levels, and lower IL-8 levels. Our results show that HD treatment and CKD cause influence T cell activation status.

Comparing Humoral and Cellular Adaptive Immunity during Convalescent Phase of COVID-19 in Hemodialysis Patients and Kidney Transplant Recipients

Background. It is still unclear whether COVID-19 convalescent kidney transplant recipients (KTR) and hemodialysis (HD) patients can develop anti-SARS-CoV-2 adaptive immunity. The aim was to characterize and compare the immune response to the virus in HD patients and KTR. Methods. The study included 26 HD patients and 54 KTR—both convalescent (14 HD, 25 KTR) and unexposed. The immune response was assessed by determining the anti-SARS-CoV-2 antibodies in serum and specific T cell response via the interferon-gamma release assay (IGRA). Moreover, blood-morphology-derived parameters, immune cell phenotypes, and acute phase reactants were evaluated. Results. KRT and HD convalescents presented similar serum levels of anti-SARS-CoV-2 IgG and IgA. A negative correlation occurred between IgG and time after the infection was observed. There was a strong relationship between the prevalence of anti-SARS-CoV-2 cellular and humoral responses in both groups. Convalescent IGRA response was significantly higher in HD patients compared to KTR. Conclusions. HD patients and KTR develop humoral and cellular responses after COVID-19. The antibodies levels are similar in both groups of patients. SARS-CoV-2-reactive T cell response is stronger in HD patients compared to KTR. The SARS-CoV-2-specific IgG level decreases with time while IgA and a cellular response are maintained. IGRA proved to be a valuable test for the assessment of specific cellular immunity in immunocompromised HD patients and KTR.

The Magnitude and Functionality of SARS-CoV-2 Reactive Cellular and Humoral Immunity in Transplant Population Is Similar to the General Population Despite Immunosuppression

BACKGROUND

The ability of transplant (Tx) patients to generate a protective antiviral response under immunosuppression is pivotal in COVID-19 infection. However, analysis of immunity against SARS-CoV-2 is currently lacking.

METHODS

Here, we analyzed T cell immunity directed against SARS-CoV-2 spike-, membrane-, and nucleocapsid-protein by flow cytometry and spike-specific neutralizing antibodies in 10 Tx in comparison to 26 nonimmunosuppressed (non-Tx) COVID-19 patients.

RESULTS

Tx patients (7 renal, 1 lung, and 2 combined pancreas-kidney Txs) were recruited in this study during the acute phase of COVID-19 with a median time after SARS-CoV-2-positivity of 3 and 4 d for non-Tx and Tx patients, respectively. Despite immunosuppression, we detected antiviral CD4+ T cell-response in 90% of Tx patients. SARS-CoV-2-reactive CD4+ T cells produced multiple proinflammatory cytokines, indicating their potential protective capacity. Neutralizing antibody titers did not differ between groups. SARS-CoV-2-reactive CD8+ T cells targeting membrane- and spike-protein were lower in Tx patients, albeit without statistical significance. However, frequencies of anti-nucleocapsid-protein-reactive, and anti-SARS-CoV-2 polyfunctional CD8+ T cells, were similar between patient cohorts. Tx patients showed features of a prematurely aged adaptive immune system, but equal frequencies of SARS-CoV-2-reactive memory T cells.

CONCLUSIONS

In conclusion, a polyfunctional T cell immunity directed against SARS-CoV-2 proteins as well as neutralizing antibodies can be generated in Tx patients despite immunosuppression. In comparison to nonimmunosuppressed patients, no differences in humoral and cellular antiviral-immunity were found. Our data presenting the ability to generate SARS-CoV-2-specific immunity in immunosuppressed patients have implications for the handling of SARS-CoV-2-infected Tx patients and raise hopes for effective vaccination in this cohort.

The Role of Ageing and Parenchymal Senescence on Macrophage Function and Fibrosis

In this review, we examine senescent cells and the overlap between the direct biological impact of senescence and the indirect impact senescence has via its effects on other cell types, particularly the macrophage. The canonical roles of macrophages in cell clearance and in other physiological functions are discussed with reference to their functions in diseases of the kidney and other organs. We also explore the translational potential of different approaches based around the macrophage in future interventions to target senescent cells, with the goal of preventing or reversing pathologies driven or contributed to in part by senescent cell load in vivo.

Rationale and design of the OPTIMIZE trial: OPen label multicenter randomized trial comparing standard IMmunosuppression with tacrolimus and mycophenolate mofetil with a low exposure tacrolimus regimen In combination with everolimus in de novo renal transplantation in Elderly patients

BACKGROUND

In 2019, more than 30 % of all newly transplanted kidney transplant recipients in The Netherlands were above 65 years of age. Elderly patients are less prone to rejection, and death censored graft loss is less frequent compared to younger recipients. Elderly recipients do have increased rates of malignancy and infection-related mortality. Poor kidney transplant function in elderly recipients may be related to both pre-existing (i.e. donor-derived) kidney damage and increased susceptibility to nephrotoxicity of calcineurin inhibitors (CNIs) in kidneys from older donors. Hence, it is pivotal to shift the focus from prevention of rejection to preservation of graft function and prevention of over-immunosuppression in the elderly. The OPTIMIZE study will test the hypothesis that reduced CNI exposure in combination with everolimus will lead to better kidney transplant function, a reduced incidence of complications and improved health-related quality of life for kidney transplant recipients aged 65 years and older, compared to standard immunosuppression.

METHODS

This open label, randomized, multicenter clinical trial will include 374 elderly kidney transplant recipients (≥ 65 years) and consists of two strata. Stratum A includes elderly recipients of a kidney from an elderly deceased donor and stratum B includes elderly recipients of a kidney from a living donor or from a deceased donor < 65 years. In each stratum, subjects will be randomized to a standard, tacrolimus-based immunosuppressive regimen with mycophenolate mofetil and glucocorticoids or an adapted immunosuppressive regimen with reduced CNI exposure in combination with everolimus and glucocorticoids. The primary endpoint is 'successful transplantation', defined as survival with a functioning graft and an eGFR ≥ 30 ml/min per 1.73 m2 in stratum A and ≥ 45 ml/min per 1.73 m2 in stratum B, after 2 years, respectively.

CONCLUSIONS

The OPTIMIZE study will help to determine the optimal immunosuppressive regimen after kidney transplantation for elderly patients and the cost-effectiveness of this regimen. It will also provide deeper insight into immunosenescence and both subjective and objective outcomes after kidney transplantation in elderly recipients.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT03797196 , registered January 9th, 2019. EudraCT: 2018-003194-10, registered March 19th, 2019.

Association of Premature Immune Aging and Cytomegalovirus After Solid Organ Transplant

Immune function is altered with increasing age. Infection with cytomegalovirus (CMV) accelerates age-related immunological changes resulting in expanded oligoclonal memory CD8 T cell populations with impaired proliferation, signaling, and cytokine production. As a consequence, elderly CMV seropositive (CMV⁺) individuals have increased mortality and impaired responses to other infections in comparison to seronegative (CMV^–) individuals of the same age. CMV is also a significant complication after organ transplantation, and recent studies have shown that CMV-associated expansion of memory T cells is accelerated after transplantation. Thus, we investigated whether immune aging is accelerated post-transplant, using a combination of telomere length, flow cytometry phenotyping, and single cell RNA sequencing. Telomere length decreased slightly in the first year after transplantation in a subset of both CMV⁺ and CMV^– recipients with a strong concordance between CD57⁺ cells and short telomeres. Phenotypically aged cells increased post-transplant specifically in CMV⁺ recipients, and clonally expanded T cells were enriched for terminally differentiated cells post-transplant. Overall, these findings demonstrate a pattern of accelerated aging of the CD8 T cell compartment in CMV⁺ transplant recipients.

Uremia-Associated Immunological Aging and Severity of COVID-19 Infection

One year after the start of the COVID-19 pandemic it has become clear that some groups of individuals are at particular high risk of a complicated course of infection resulting in high morbidity and mortality. Two specific risk factors are most prominent, old age and the presence of co-morbidity. Recent studies have shown that patients with compromised renal function, especially those treated with renal replacement therapy or having received a kidney transplant are at a much higher risk for severe COVID infection and increased mortality. This may be in part due to the increased prevalence of co-morbid conditions in these patients but specific alterations in their immune system, reflecting premature immunological aging, may be equally important. In this review the different aspects, in particular thymus function and memory T cell expansion, of uremia-associated immunological aging are reviewed with respect to COVID 19 infection. In essence, the decreased generation of naïve T cells may be instrumental in suboptimal anti-viral immune responses while the relatively uncontrolled expansion of effector T cells may facilitate the feared phase of the COVID-19 infection with excessive and live-threatening inflammation of the lung parenchyma.

Effects of Different Dialysis Strategies on Inflammatory Cytokine Profile in Maintenance Hemodialysis Patients with COVID-19: A Randomized Trial

Uncontrolled inflammation plays a relevant role in the pathogenesis of coronavirus disease-19 (COVID-19). Here, we studied the time trend of inflammatory markers in a population of hemodialysis (HD) patients affected by COVID-19, undergoing two different dialysis approaches. In a prospective study, thirty-one maintenance HD patients with COVID-19 were randomized to expanded HD (HDx), performed using a medium cut-off membrane, or standard treatment using a protein-leaking dialyzer (PLD). Circulating levels of interleukin-6 (IL-6), interleukin-8 (IL-8), interleukin-10 (IL-10), soluble TLR4 (sTLR4), and interferon-gamma (IFN-γ), were collected at diagnosis, and one and two weeks after. Compared with 14 non-infected HD patients, COVID-19 patients showed lymphopenia and higher ferritin and lactate dehydrogenase levels. Moreover, COVID-19 patients had higher levels of IL-10 (15.2 (12.5) vs. 1.2 (1.4) pg/mL, p = 0.02). Twenty-nine patients were randomized to HDx (n = 15) or PLD (n = 14). After a single treatment, IL-8 showed a significant reduction in both groups, whereas IL-10 decreased only in HDx. All over the study, there were no significant modifications in circulating cytokine levels between the two groups, except for a parallel increase of IL-8 and IL-10 at one week control in the HDx group. No correlations were found between cytokine levels and clinical outcomes. In maintenance HD patients, COVID-19 is not related to a sustained inflammatory response. Therefore, modulation of inflammation seems not to be a suitable therapeutic target in this specific population.

Herpes Zoster in Solid Organ Transplantation: Incidence and Risk Factors

Background

Studies on herpes zoster (HZ) incidence in solid organ transplant (SOT) recipients report widely varying numbers. We investigated HZ incidence, severity, and risk factors in recipients of four different SOTs, with a follow-up time of 6-14 years.

Methods

Records of 1,033 transplant recipients after first heart (HTx: n = 211), lung (LuTx: n = 121), liver (LiTx: n = 258) and kidney (KTx: n = 443) transplantation between 2000 and 2014 were analyzed for VZV-PCR, clinical signs of HZ, and complications.

Results

HZ was diagnosed in 108 of 1,033 patients (10.5%): 36 HTx, 17 LuTx, 15 LiTx, and 40 KTx recipients. Overall HZ incidence rate after HTx (30.7 cases/1,000 person-years (PY)), LuTx (38.8 cases/1,000 PY), LiTx (22.7 cases/1,000 PY) and KTx (14.5 cases/1,000 PY) was significantly higher than in the general 50-70 year population. Multivariable analysis demonstrated age ≥50 years at transplantation (p = 0.038, RR 1.536), type of organ transplant (overall p = 0.002; LuTx p = 0.393; RR 1.314; LiTx p = 0.011, RR 0.444; KTx p = 0.034, RR 0.575), CMV prophylaxis (p = 0.043, RR 0.631) and type of anti-rejection therapy (overall p = 0.020; methylprednisolone p = 0.008, RR 0.475; r-ATG p = 0.64, RR1.194) as significant risk factors. Complications occurred in 33 of 108 (31%) patients (39% of HTx, 47% of LuTx, 20% of LiTx, 20% of KTx): post-herpetic neuralgia, disseminated disease, and cranial nerve involvement.

Conclusion

HZ incidence and severity in SOT recipients are most pronounced after heart and lung transplantation, in older patients, and when CMV prophylaxis is lacking.

Decreased Peripheral Naïve T Cell Number and Its Role in Predicting Cardiovascular and Infection Events in Hemodialysis Patients

Patients with end-stage renal disease (ESRD) are at high risk of morbidity and mortality from cardiovascular and infectious diseases, which have been found to be associated with a disturbed immune response. Accelerated T-cell senescence is prevalent in these patients and considered a significant factor contributing to increased risk of various morbidities. Nevertheless, few studies have explicated the relevance of T-cell senescence to these fatal morbidities in ESRD patients. In this study, we designed a longitudinal prospective study to evaluate the influence of T-cell senescence on cardiovascular events (CVEs) and infections in hemodialysis (HD) patients. Clinical outcomes of 404 patients who had been on HD treatment for at least 6 months were evaluated with respect to T-cell senescence determined using flow cytometry. We found that T-cell senescence was associated with systemic inflammation. High-sensitivity C-reactive protein was positively associated with decreased naïve T cell levels. Elevated tumor necrosis factor-α and interleukin 6 levels were significantly associated with lower central memory T cell and higher T effector memory CD45RA cell levels. Decreased CD4⁺ naïve T cell count was independently associated with CVEs, whereas decreased CD8⁺ naïve T cell count was independently associated with infection episodes in HD patients. In conclusion, HD patients exhibited accelerated T-cell senescence, which was positively related to inflammation. A reduction of naïve T cell could be a strong predictor of CVEs and infection episodes in HD patients.

Memory T Cells in Transplantation: Old Challenges Define New Directions

Immunologic memory is the ability of adaptive immune system to quickly and specifically recognize previously encountered antigens and initiate an effector response. Alloreactive memory cells can mount rapid and robust responses to the transplanted organ resulting in allograft injury. Thus preexisting humoral or cellular memory alloresponses are typically associated with poor graft outcomes in experimental and clinical transplantation. While both B and T lymphocytes exhibit memory responses, this review discusses recent updates on the biology of memory T cells and their relevance to the field of transplantation. Three major areas of focus are the emergence and characterization of tissue resident memory T cells, manipulation of T cell metabolic pathways, and the latest promising approaches to targeting detrimental T cell memory in the settings of organ transplantation.

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.