ATG-induced accelerated immune senescence: clinical implications in renal transplant recipients

Depletion of SASP senescent cardiomyocytes with senolytic drugs confers therapeutic effects in doxorubicin-related cardiotoxicity

Doxorubicin (Dox), an anthracycline antibiotic, is widely used in cancer treatment. Although its antitumor efficacy appears significant, its clinical use is greatly restricted by its induction of cardiotoxicity. Cardiac senescence drives the Dox-induced cardiotoxicity, but whether diminishing these senescent cardiomyocytes could alleviate the cardiotoxicity remains unclear. Here, we assessed whether senescent cardiomyocytes have a senescence-associated secretory phenotype (SASP) that affects healthy non-senescent cardiomyocytes, rendering them senescent via the delivery of exosomes. Additionally, we explored whether targeting SASP senescent cardiomyocytes using a Bcl-2 inhibitor could alleviate cardiotoxicity. Cardiac damage was induced in a mouse model of continuous Dox treatment in vivo, and cardiomyocytes in vitro. Immunofluorescence of the senescence markers of Cdkn2a, Cdkn1a and γ-H2A.X was used to assess the SASP in the Dox-treated heart. To explore the molecular mechanisms involved, the Bcl-2 inhibitor ABT-199 was employed to eliminate SASP senescent cardiomyocytes. We show that the cardiomyocytes acquire a SASP during Dox treatment. The senescent cardiomyocytes upregulated Bcl-2, although treatment of mice with ABT-199 selectively eliminated SASP senescent cardiomyocytes involved in Dox-induced cardiotoxicity, thus leading to partial alleviation of Dox-induced cardiotoxicity. Moreover, we concluded that SASP factors secreted by senescent cardiomyocytes induced by Dox renders otherwise healthy cardiomyocytes senescent through exosome delivery. Our findings suggest that SASP senescent cardiomyocytes are a significant component of the pathogenesis of Dox-dependent cardiotoxicity and indicate that targeting the clearance of SASP senescent cardiomyocytes could be a new therapeutic approach for Dox-induced cardiac injury.

Incidence, Risk Factors, and Outcomes of De Novo Malignancy following Kidney Transplantation

Introduction: Post-transplant malignancy is a significant cause of morbidity and mortality following kidney transplantation often emerging after medium- to long-term follow-up. To understand the risk factors for the development of de novo post-transplant malignancy (DPTM), this study aimed to assess the incidence, risk factors, and outcomes of DPTM at a single nephrology centre over two decades. Methods: This retrospective cohort study included 963 kidney transplant recipients who underwent kidney transplantation between January 2000 and December 2020 and followed up over a median follow-up of 7.1 years (IQR 3.9-11.4). Cox regression models were used to identify the significant risk factors of DPTM development, the association of DPTM with graft survival, and mortality with a functioning graft. Results: In total, 8.1% of transplant recipients developed DPTM, and the DPTM incidence rate was 14.7 per 100 patient-years. There was a higher mean age observed in the DPTM group (53 vs. 47 years, p < 0.001). The most affected organ systems were genitourinary (32.1%), gastrointestinal (24.4%), and lymphoproliferative (20.5%). Multivariate Cox analysis identified older age at transplant (aHR 9.51, 95%CI: 2.60-34.87, p < 0.001) and pre-existing glomerulonephritis (aHR 3.27, 95%CI: 1.10-9.77, p = 0.03) as significant risk factors for DPTM. Older age was significantly associated with poorer graft survival (aHR 8.71, 95%CI: 3.77-20.20, p < 0.001). When age was excluded from the multivariate Cox model, DPTM emerged as a significant risk factor for poor survival (aHR 1.76, 95%CI: 1.17-2.63, p = 0.006). Conclusion: These findings underscore the need for tailored screening, prevention, and management strategies to address DPTM in an aging and immunosuppressed kidney transplant population.

Pulmonary, Hepatic, and Allogeneic Hematopoietic Stem Cell Transplantation in Patients with Telomere Biology Disorders

PURPOSE OF THE REVIEW

This study aimed to summarize evidence and provide consensus-based guidelines for management of transplantation in patients with telomere biology disorders (TBD). Specifically, this review focuses on clinical management of lung, liver, and bone marrow transplantation in TBD patients.

RECENT FINDINGS

TBD patients have specific unique biological vulnerabilities such as T cell immunodeficiency, susceptibility to infections, hypersensitivity to chemotherapy and radiation, and cytopenias. Furthermore, multiple organ involvement at diagnosis makes clinical management especially challenging due to higher degree of organ damage, and stress-induced telomeric crisis. Sequential and combined organ transplants, development of novel radiation and alkylator-free conditioning regimen, and use of novel drugs for graft-versus-host disease prophylaxis are some of the recent updates in the field. Multidisciplinary management is essential to optimize transplant outcomes in patients with TBD. In this review, we provide consensus-based transplant management guidelines for clinical management of transplant in TBD.

Triglyceride-Glucose Index and Cardiovascular Events in Kidney Transplant Recipients

Introduction

Kidney transplant recipients (KTRs) have an increased risk of cardiovascular (CV) events (CVEs) compared with the general population. The impact of insulin resistance on CV risk after transplantation is not well defined.

Methods

We tested whether triglyceride-glucose (TyG) index, a surrogate marker of insulin resistance, may predict posttransplant CVEs in a cohort of 715 consecutive KTRs all included 1 year after transplant.

Results

Follow-up was 9.1 ± 4.6 years. Mean TyG at inclusion was 4.75 ± 0.29 (median, 4.73 [4.14-5.84]). In multiple regression analysis, having a TyG above the median value was associated with higher body mass index (BMI), low high-density lipoprotein (HDL) cholesterol level, and greater urinary protein excretion. A total of 127 CVEs (17.7%) occurred during the study period. In univariate analysis, TyG was strongly associated with CVE occurrence (hazard ratio [HR] 2.06, 95% CI 1.42-3.50, for each increase of 0.1 in TyG, P < 0.001). The best predictive value was 4.87 (HR 6.32, 95% CI 3.30-12.11, P < 0.001). The risk of CVE gradually increased with higher TyG index (quartile 2, HR 1.71, 95% CI 0.84-5.20, P = 0.139; quartile 3, HR 3.12, 95% CI 1.61-6.02, P < 0.001; quartile 4, HR 7.46, 95% CI 4.03-13.80, P < 0.001, vs. quartile 1). TyG remained associated with CVE in multivariate analysis (HR 2.11, 95% CI 1.22-3.68, for each increase of 0.1 in TyG, P < 0.001).

Conclusion

Insulin resistance, as measured by the TyG index is strongly associated with CVE in KTRs. Improving insulin sensitivity seems to be a major issue to prevent CV morbidity and mortality in this high-risk population.

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.

LincRNA-p21 Promotes Cellular Senescence by Down-regulating the Wnt/β-catenin Pathway in MPP+-treated SH-SY5Y Cells

AIM AND OBJECTIVE

Long intergenic non-coding RNA-p21 (lincRNA-p21) plays a critical role in various senescence-associated physiological and pathological conditions. We aimed to explore the senescence-associated effects of lincRNA-p21 in 1-methyl-4-phenylpyridinium (MPP+) treated neuroblastoma SH-SY5Y cell line as a therapeutic target.

MATERIALS AND METHODS

The RNA expression levels of lincRNA-p21, p53, p16, and telomere length were examined with reverse transcription-quantitative polymerase chain reaction (RTqPCR). The Telo TAGGG™ Telomerase PCR ELISA PLUS Kit was used to determine telomerase activity. Cellular viability was evaluated with the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and lactate dehydrogenase (LDH) assay. Western blot was performed to analyze β-catenin protein expression. Besides, oxidative stress was evaluated by Jaggregate- forming delocalized lipophilic cation, 5,5',6,6'-tetrachloro-1,1',3,3'- tetraethylbenzimidazolocarbocyanine++ + iodide (JC‑1) stain, fluorescence spectrophotometry, colorimetric assay, and malondialdehyde (MDA) formation.

RESULTS

This research demonstrated that MPP+ caused a distinct increase in the expression of LincRNA- p21 in SH-SY5Y cells. MPP+ induced cellular senescence with decreasing cellular proliferation and viability, increasing expression levels of senescence-associated makers such as genes p53 and p16, accompanied by significantly decreasing telomere length and telomerase activity. At the same time, these effects were abolished by silencing lincRNA-p21 with small interfering RNA (siRNA). On the contrary, β-catenin silencing contributes to reversing anti-senescent effects caused by lincRNA-p21 silencing. Moreover, modifying lincRNA-p21 exerted an anti-senescent influence depending on decreasing oxidant stress.

CONCLUSION

Our study showed that in the treatment of MPP+, lincRNA-p21 might serve a role in the SH-SY5Y cell senescence by modulating the Wnt/β-catenin pathway, as well as increasing oxidant stress. Thus, trying to target lincRNA-p21 may have important therapeutic and practical implications for PD.

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.

T-cell Exhaustion in Organ Transplantation

Exhaustion of T cells occurs in response to long-term exposure to self and foreign antigens. It limits T cell capacity to proliferate and produce cytokines, leading to an impaired ability to clear chronic infections or eradicate tumors. T-cell exhaustion is associated with a specific transcriptional, epigenetic, and metabolic program and characteristic cell surface markers' expression. Recent studies have begun to elucidate the role of T-cell exhaustion in transplant. Higher levels of exhausted T cells have been associated with better graft function in kidney transplant recipients. In contrast, reinvigorating exhausted T cells by immune checkpoint blockade therapies, while promoting tumor clearance, increases the risk of acute rejection. Lymphocyte depletion and high alloantigen load have been identified as major drivers of T-cell exhaustion. This could account, at least in part, for the reduced rates of acute rejection in organ transplant recipients induced with thymoglobulin and for the pro-tolerogenic effects of a large organ such as the liver. Among the drugs that are widely used for maintenance immunosuppression, calcineurin inhibitors have a contrasting inhibitory effect on exhaustion of T cells, while the influence of mTOR inhibitors is still unclear. Harnessing or encouraging the natural processes of exhaustion may provide a novel strategy to promote graft survival and transplantation tolerance.

De Novo Malignancies after Kidney Transplantation

Cancer is an important outcome after kidney transplantation because it is the second leading cause of death in most Western countries. The excess risk of cancer after transplantation is approximately two to three times higher than the age- and sex-matched general population, driven largely by viral- and immune-related cancers. Once cancer develops, outcomes are generally poor, particularly for those with melanoma, renal cell carcinoma, and post-transplant lymphoproliferative disease. More importantly, effective screening and treatment strategies are limited in this high-risk population. In this review, we begin with a patient's journey that maps the experience of living with a kidney transplant and understand the patient's knowledge, education, and experience of cancer in the context of transplantation. The epidemiology and burden of cancer in recipients of kidney transplants, along with the up-to-date screening and treatment strategies, are discussed. We also focus on the current understanding of optimal care for recipients of kidney transplants who are living with cancer from the patients' perspectives.

Effects of Reduced-Dose Anti-Human T-Lymphocyte Globulin on Overall and Donor-Specific T-Cell Repertoire Reconstitution in Sensitized Kidney Transplant Recipients

Background

Pre-sensitized kidney transplant recipients have a higher risk for rejection following kidney transplantation and therefore receive lymphodepletional induction therapy with anti-human T-lymphocyte globulin (ATLG) whereas non-sensitized patients are induced in many centers with basiliximab. The time course of lymphocyte reconstitution with regard to the overall and donor-reactive T-cell receptor (TCR) specificity remains elusive.

Methods/Design

Five kidney transplant recipients receiving a 1.5-mg/kg ATLG induction therapy over 7 days and five patients with 2 × 20 mg basiliximab induction therapy were longitudinally monitored. Peripheral mononuclear cells were sampled pre-transplant and within 1, 3, and 12 months after transplantation, and their overall and donor-reactive TCRs were determined by next-generation sequencing of the TCR beta CDR3 region. Overall TCR repertoire diversity, turnover, and donor specificity were assessed at all timepoints.

Results

We observed an increase in the donor-reactive TCR repertoire after transplantation in patients, independent of lymphocyte counts or induction therapy. Donor-reactive CD4 T-cell frequency in the ATLG group increased from 1.14% + -0.63 to 2.03% + -1.09 and from 0.93% + -0.63 to 1.82% + -1.17 in the basiliximab group in the first month. Diversity measurements of the entire T-cell repertoire and repertoire turnover showed no statistical difference between the two induction therapies. The difference in mean clonality between groups was 0.03 and 0.07 pre-transplant in the CD4 and CD8 fractions, respectively, and was not different over time (CD4: F(1.45, 11.6) = 0.64 p = 0.496; CD8: F(3, 24) = 0.60 p = 0.620). The mean difference in R20, a metric for immune dominance, between groups was -0.006 in CD4 and 0.001 in CD8 T-cells and not statistically different between the groups and subsequent timepoints (CD4: F(3, 24) = 0.85 p = 0.479; CD8: F(1.19, 9.52) = 0.79 p = 0.418).

Conclusion

Reduced-dose ATLG induction therapy led to an initial lymphodepletion followed by an increase in the percentage of donor-reactive T-cells after transplantation similar to basiliximab induction therapy. Furthermore, reduced-dose ATLG did not change the overall TCR repertoire in terms of a narrowed or skewed TCR repertoire after immune reconstitution, comparable to non-depletional induction therapy.

Risk of Severe Coronavirus Disease 2019 Infection in Kidney Transplant Recipients

Background

Despite all efforts, the incidence of severe coronavirus disease 2019 (COVID-19) infection has been high in renal transplant recipients, as in other groups (eg, older adults, patients with comorbidities or immunosuppression). The detection of any possible predictor of gravity could improve the early approach in these patients.

Patients and methods

We registered data from renal transplant recipients with severe acute respiratory syndrome coronavirus 2 (SARS-COV-2) infection in our area for a year (March 2020 to March 2021). We collected demographics, comorbidity, body mass index, lymphocyte count, and vitamin D levels before the diagnosis. We performed statistical analysis using SPSS Statistics version 20 (IBM Corp, Armonk, NY, United States).

Results

Of 63 patients, 57.1% required hospital admission and 14.3% required intensive care. The incidence of acute renal failure was 28.6%; 34.9% developed hyperinflammatory syndrome; 67% had lymphopenia, which was severe in 13.1%; and 11 patients died. There was significant correlation between lymphocyte count before and during the infection. For hospitalization, we found differences in age, pulmonary disease, and renal function. Related factors for admission to an intensive care unit were obesity, severe lymphopenia, altered renal function, and low level of vitamin D. Predictors for mortality were age, renal function, and minimum lymphocyte count.

Conclusion

In kidney transplant recipients with COVID-19 infection, renal function determines hospitalization, and body mass index determines admission to an intensive care unit. Previous vitamin D levels are also significantly lower in patients requiring intensive care. The analysis of lymphocyte count previous to infection is correlated with the minimum level during the disease, which is a predictor of mortality, and could be a prognosis factor.

MicroRNA therapy confers anti-senescent effects on doxorubicin-related cardiotoxicity by intracellular and paracrine signaling

Doxorubicin (Dox), an important anthracycline, is a potent anticancer agent that is used for treating solid tumors and hematologic malignancies. However, its clinical use is hampered by cardiac cardiotoxicity. This study aimed to investigate the cardioprotective potential of miR-199a-3p. Continuous Dox treatment not only markedly induced cardiomyocyte senescence but also resulted in a growing number of senescence-associated secretory phenotype (SASP) cardiomyocytes, frequently leading to heart senescence. This study showed that miR-199a-3p was downregulated in cardiomyocytes when exposed to Dox. The cardiac-specific overexpression of miR-199a-3p promoted cell cycle re-entry and cell proliferation, resulting in relief from cardiac senescence. Also, the elevation of miR-199a-3p inhibited the generation of SASP, thus, hampering the spread of senescence. In cardiomyocytes, the modulation of miR-199a-3p changed the levels of senescence-related protein GATA4. The ectopic expression of GATA4 blunted the anti-senescence effect of miR-199a-3p. Together, the data supported a role for miR-199a-3p during Dox cardiotoxicity. The elevation of miR-199a-3p might provide a dual therapeutic advantage in Dox cardiotoxicity therapy by simultaneously preventing cardiac senescence and reducing the spread of senescence.

Functional Consequences of Memory Inflation after Solid Organ Transplantation

CMV is a major infectious complication following solid organ transplantation. Reactivation of CMV leads to memory inflation, a process in which CD8 T cells expand over time. Memory inflation is associated with specific changes in T cell function, including increased oligoclonality, decreased cytokine production, and terminal differentiation. To address whether memory inflation during the first year after transplantation in human subjects alters T cell differentiation and function, we employed single-cell-matched TCRαβ and targeted gene expression sequencing. Expanded T cell clones exhibited a terminally differentiated, immunosenescent, and polyfunctional phenotype whereas rare clones were less differentiated. Clonal expansion occurring between pre- and 3 mo posttransplant was accompanied by enhancement of polyfunctionality. In contrast, polyfunctionality and differentiation state were largely maintained between 3 and 12 mo posttransplant. Highly expanded clones had a higher degree of polyfunctionality than rare clones. Thus, CMV-responsive CD8 T cells differentiated during the pre- to posttransplant period then maintained their differentiation state and functional capacity despite posttransplant clonal expansion.

End-Stage Renal Disease-Related Accelerated Immune Senescence: Is Rejuvenation of the Immune System a Therapeutic Goal?

End-stage renal disease (ESRD) patients exhibit clinical features of premature ageing, including frailty, cardiovascular disease, and muscle wasting. Accelerated ageing also concerns the immune system. Patients with ESRD have both immune senescence and chronic inflammation that are resumed in the so-called inflammaging syndrome. Immune senescence is particularly characterised by premature loss of thymic function that is associated with hyporesponsiveness to vaccines, susceptibility to infections, and death. ESRD-related chronic inflammation has multiple causes and participates to accelerated cardiovascular disease. Although, both characterisation of immune senescence and its consequences are relatively well-known, mechanisms are more uncertain. However, prevention of immune senescence/inflammation or/and rejuvenation of the immune system are major goal to ameliorate clinical outcomes of ESRD patients.

Cellular and humoral response after MRNA-1273 SARS-CoV-2 vaccine in kidney transplant recipients

According to preliminary data, seroconversion after mRNA SARS-CoV-2 vaccination might be unsatisfactory in Kidney Transplant Recipients (KTRs). However, it is unknown if seronegative patients develop at least a cellular response that could offer a certain grade of protection against SARS-CoV-2. To answer this question, we prospectively studied 148 recipients of either kidney (133) or kidney-pancreas (15) grafts with assessment of IgM/IgG spike (S) antibodies and ELISpot against the nucleocapside (N) and the S protein at baseline and 2 weeks after receiving the second dose of the mRNA-1273 (Moderna) vaccine. At baseline, 31 patients (20.9%) had either IgM/IgG or ELISpot positivity and were considered to be SARS-CoV-2-pre-immunized, while 117 (79.1%) patients had no signs of either cellular or humoral response and were considered SARS-CoV-2-naïve. After vaccination, naïve patients who developed either humoral or cellular response were finally 65.0%, of which 29.9% developed either IgG or IgM and 35.0% S-ELISpot positivity. Factors associated with vaccine unresponsiveness were diabetes and treatment with antithymocytes globulins during the last year. Side effects were consistent with that of the pivotal trial and no DSAs developed after vaccination. In conclusion, mRNA-1273 SARS-CoV-2 vaccine elicits either cellular or humoral response in almost two thirds of KTRs.

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.

A comparative study of human-and rhesus-specific antithymocyte globulins in Rhesus macaques

Rabbit antithymocyte globulin (RATG) preparations are widely used in transplantation. They are developed in vivo against thymocytes and contain polyclonal antibodies specific for myriad cellular targets. The rhesus monkey is commonly used as a preclinical transplant model, but the fidelity of commercially available human-specific RATGs to anticipate the effects of RATGs in rhesus has not been established. We therefore developed two rhesus-specific ATGs (rhATG) and compared them to human-specific RATG (huATG, Thymoglobulin^® ) in rhesus monkeys, assessing the magnitude and phenotype of depletion peripherally and in lymph nodes. Four primates were assigned to each group and received 20 mg/kg of drug. Depletion, repopulation, and changes in lymphocyte subsets were evaluated in peripheral blood and lymph nodes by flow cytometry over four months. We observed similar qualitative changes in lymphocyte subsets, but a generally more profound depletion with huATG compared to either rhATG. Peripheral homeostatic proliferation rather than thymic output was the major mechanism for repopulation with all RATGs. Repopulation was slower but qualitatively similar when examining RATGs in additional animals receiving concomitant chronic immunosuppression. Depletional induction is similar to human- and rhesus-specific RATGs in rhesus macaques. Both rhesus- and human-specific agents appear appropriate for preclinical modeling of clinical RATG use.

Pathogenesis of inclusion body myositis

PURPOSE OF REVIEW

To review the pathogenesis of inclusion body myositis (IBM).

RECENT FINDINGS

IBM is an autoimmune disease. Multiple arms of the immune system are activated, but a direct attack on muscle fibers by highly differentiated T cells drives muscle destruction.

SUMMARY

Further understanding of the pathogenesis of IBM guides rational approaches to developing therapeutic strategies.

Potential Effects of Immunosuppression on Oxidative Stress and Atherosclerosis in Kidney Transplant Recipients

Chronic kidney disease is a public health problem that, depending on the country, affects approximately 8-13% of the population, involving both males and females of all ages. Renal replacement therapy remains one of the most costly procedures. It is assumed that one of the factors influencing the course of chronic kidney disease might be oxidative stress. It is believed that the main mediators of oxidative stress are reactive oxygen species (ROS). Transiently increased concentrations of ROS play a significant role in maintaining an organism's homeostasis, as they are part of the redox-related signaling, and in the immune defense system, as they are produced in high amounts in inflammation. Systemic oxidative stress can significantly contribute to endothelial dysfunction along with exaggeration of atherosclerosis and development of cardiovascular disease, the leading cause of mortality in patients with kidney disease. Moreover, the progression of chronic kidney disease is strictly associated with the atherosclerotic process. Transplantation is the optimal method for renal replacement therapy. It improves better quality of life and prolongs survival compared with hemodialysis and peritoneal dialysis; however, even a successful transplantation does not correct the abnormalities found in chronic kidney disease. As transplantation reduces the concentration of uremic toxins, which are a factor of inflammation per se, both the procedure itself and the subsequent immunosuppressive treatment may be a factor that increases oxidative stress and hence vascular sclerosis and atherosclerotic cardiovascular disease. In the current work, we review the effect of several risk factors in kidney transplant recipients as well as immunosuppressive therapy on oxidative stress.

Evaluation of Thymic Output and Regulatory T Cells in Kidney Transplant Recipients with Chronic Antibody-Mediated Rejection

Background

Regulatory T cells (Tregs) and recent thymic emigrants (RTEs) have an essential role in the regulation of allogeneic immune responses. However, their mechanisms of action in chronic antibody-mediated rejection (cAMR) are still unclear. In this study, we aimed to compare Treg and RTE levels between stable graft function (SGF) patients and cAMR subjects after kidney transplantation.

Method

Mononuclear cells (MNs) were separated from peripheral blood, and flow cytometry analysis was performed for detection of CD4⁺ and CD25^high as Treg markers and CD4⁺, CD31⁺, and CD45RA⁺ as RTE immunophenotyping markers.

Result

The level of peripheral Treg cells was significantly lower in cAMR subjects in comparison to stable graft function patients. Moreover, SGF patients who had received cyclosporine A had a higher level of Treg in comparison to the tacrolimus recipients. Nevertheless, the RTE level between SGF and cAMR patients did not show any significant differences.

Conclusion

It seems that Treg cells are significantly associated with transplant outcomes in cAMR patients, and prescribed immunosuppressive drugs can influence the frequency of this crucial subset of T cells. Although these drugs are beneficial and inevitable for allograft maintenance, more investigations are needed to elucidate their complete effects on different immune cell subsets which some of them like Tregs are in favor of transplant tolerance. Besides, the thymic output is seemingly not a beneficial biomarker for predicting cAMR; however, more in vivo and in vitro studies are needed for revealing the precise role of Tregs and RTEs in the transplantation context.

Relationship between antithymocyte globulin, T cell phenotypes, and clinical outcomes in pediatric kidney transplantation

Depletional induction using antithymocyte globulin (ATG) reduces rates of acute rejection in adult kidney transplant recipients, yet little is known about its effects in children. Using a longitudinal cohort of 103 patients in the Immune Development in Pediatric Transplant (IMPACT) study, we compared T cell phenotypes after ATG or non-ATG induction. We examined the effects of ATG on the early clinical outcomes of alloimmune events (development of de novo donor specific antibody and/or biopsy proven rejection) and infection events (viremia/viral infections). Long-term patient and graft outcomes were examined using the Scientific Registry of Transplant Recipients. After ATG induction, although absolute counts of CD4 and CD8 T cells were lower, patients had higher percentages of CD4 and CD8 memory T cells with a concomitant decrease in frequency of naïve T cells compared to non-ATG induction. In adjusted and unadjusted models, ATG induction was associated with increased early event-free survival, with no difference in long-term patient or allograft survival. Decreased CD4⁺ naïve and increased CD4⁺ effector memory T cell frequencies were associated with improved clinical outcomes. Though immunologic parameters are drastically altered with ATG induction, long-term clinical benefits remain unclear in pediatric patients.

Preexisting melanoma and hematological malignancies, prognosis, and timing to solid organ transplantation: A consensus expert opinion statement

Patients undergoing evaluation for solid organ transplantation (SOT) frequently have a history of malignancy. Only patients with treated cancer are considered for SOT but the benefits of transplantation need to be balanced against the risk of tumor recurrence, taking into consideration the potential effects of immunosuppression. Prior guidelines on timing to transplant in patients with a prior treated malignancy do not account for current staging, disease biology, or advances in cancer treatments. To update these recommendations, the American Society of Transplantation (AST) facilitated a consensus workshop to comprehensively review contemporary literature regarding cancer therapies, cancer stage specific prognosis, the kinetics of cancer recurrence, as well as the limited data on the effects of immunosuppression on cancer-specific outcomes. This document contains prognosis, treatment, and transplant recommendations for melanoma and hematological malignancies. Given the limited data regarding the risk of cancer recurrence in transplant recipients, the goal of the AST-sponsored conference and the consensus documents produced are to provide expert opinion recommendations that help in the evaluation of patients with a history of a pretransplant malignancy for transplant candidacy.

A Case of Pneumocystis jirovecii Pneumonia under Belatacept and Everolimus: Benefit-Risk Balance between Renal Allograft Function and Infection

Pneumocystis jirovecii pneumonia is an opportunistic disease usually prevented by trimethoprim-sulfamethoxazole. A 49-year-old HLA-sensitized male with successful late conversion from tacrolimus-based to belatacept-based immunosuppression developed P. jirovecii pneumonia for which he presented several risks factors: low lymphocyte count with no CD4+ T cells detected since 2 years, hypogammaglobulinemia, history of acute cellular rejection 3 years before, and immunosuppressive treatment (belatacept, everolimus). Because of respiratory gravity in the acute phase, the patient was given oxygen, corticosteroids, and trimethoprim-sulfamethoxazole. Thanks to the improvement of respiratory status, and because of the renal impairment, trimethoprim-sulfamethoxazole was converted to atovaquone for 21 days. Indeed, after 1 week on intensive treatment, the benefit-risk balance favored preserving renal function according to respiratory improvement status. P. jirovecii pneumonia prophylaxis for the next 6 months was monthly aerosol of pentamidine. Long-term safety studies or early/late conversion to belatacept did not report on P. jirovecii pneumonia. Four other cases of P. jirovecii pneumonia under belatacept therapy were previously described in patients having no P. jirovecii pneumonia prophylaxis. Studies on the reintroduction of P. jiroveciipneumonia prophylaxis after conversion to belatacept would be of interest. It could be useful to continue regular evaluation within the second-year post-transplantation regarding immunosuppression: T-cell subsets and immunoglobulin G levels.

pre-existing diabetes and PTDM in kidney transplant recipients: how to handle immunosuppression

INTRODUCTION

Preexisting diabetes (PD) and post-transplant diabetes mellitus (PTDM) are common and severe comorbidities posttransplantation. The immunosuppressive regimens are modifiable risk factors.

AREAS COVERED

We reviewed Pubmed and Cochrane database and we summarize the mechanisms and impacts of available immunosuppressive treatments on the risk of PD and PTDM. We also assess the possible management of these drugs to improve glycemic parameters while considering risks inherent in transplantation.

EXPERT OPINION

PD i) increases the risk of sepsis, ii) is an independent risk factor for infection-related mortality, and iii) increases acute rejection risk. Regarding PTDM development i) immunosuppressive strategies without corticosteroids significantly reduce the risk but the price may be a higher incidence of rejection; ii) minimization or rapid withdrawal of steroids are two valuable approaches; iii) the diabetogenic role of calcineurin inhibitors(CNIs) is also well-described and is more important for tacrolimus than for cyclosporine. Reducing tacrolimus-exposure may improve glycemic parameters but also has a higher risk of rejection. PTDM risk is higher in patients that receive sirolimus compared to mycophenolate mofetil. Finally, conversion from CNIs to belatacept may offer the best benefits to PTDM-recipients in terms of glycemic parameters, graft and patient-outcomes.

The incidence of post-transplant malignancies in kidney transplant recipients treated with Rituximab

BACKGROUND

Rituximab has been proposed as induction therapy in kidney transplant recipients (KTRs) with preformed donor-specific antibodies (DSA) or a positive flow cross-match. We here evaluated whether adding rituximab was associated with a higher incidence of post-transplant malignancies (PTM) due to greater immunosuppression.

PATIENTS AND METHODS

Forty-eight HLA-sensitized KTRs received induction therapy with anti-thymocyte globulin (ATG) and rituximab because of preformed DSA or a positive flow cross-match (RTX group). They were compared with a control group of 154 patients receiving ATG alone.

RESULTS

Thirty-nine of 202 (19.3%) patients developed PTM; the rate was similar in the RTX and no-RTX groups (14.6% vs. 20.8%, respectively, P = .3). The distributions of the types of cancer were similar between the two groups, with the majority being non-melanoma skin cancer (NMSC, n = 24). The risk factors for PTM were male gender, age, history of cancer, and azathioprine.

CONCLUSION

Our data do not indicate a higher rate of post-transplantation de novo malignancies after kidney transplantation in high-immunological risk patients who received induction therapy based on ATG and rituximab.

Exosomal LncRNA-NEAT1 derived from MIF-treated mesenchymal stem cells protected against doxorubicin-induced cardiac senescence through sponging miR-221-3p

Background

The chemotherapy drug doxorubicin (Dox) is widely used for treating a variety of cancers. However, its high cardiotoxicity hampered its clinical use. Exosomes derived from stem cells showed a therapeutic effect against Dox-induced cardiomyopathy (DIC). Previous studies reported that exosomes derived from mesenchymal stem cells (MSCs) pretreated with macrophage migration inhibitory factor (MIF) (exosome^MIF) showed a cardioprotective effect through modulating long noncoding RNAs/microRNAs (lncRNAs/miRs). This study aimed to investigate the role of exosome^MIF in the treatment of DIC.

Results

Exosomes were isolated from control MSCs (exosome) and MIF-pretreated MSCs (exosome^MIF). Regulatory lncRNAs activated by MIF pretreatment were explored using genomics approaches. Fluorescence-labeled exosomes were tracked in vitro by fluorescence imaging. In vivo and in vitro, miR-221-3p mimic transfection enforced miR-221-3p overexpression, and senescence-associated β-galactosidase assay was applied to test cellular senescence. Exosomal delivering LncRNA-NEAT1 induced therapeutic effect in vivo was confirmed by echocardiography. It demonstrated that exosomes^MIF recovered the cardiac function and exerted the anti-senescent effect through LncRNA–NEAT1 transfer against Dox. TargetScan and luciferase assay showed that miR-221-3p targeted the Sirt2 3′-untranslated region. Silencing LncRNA–NEAT1 in MSCs, miR-221-3p overexpression or Sirt2 silencing in cardiomyocytes decreased the exosome^MIF-induced anti-senescent effect against Dox.

Conclusions

The results indicated exosome^MIF serving as a promising anti-senescent effector against Dox-induced cardiotoxicity through LncRNA–NEAT1 transfer, thus inhibiting miR-221-3p and leading to Sirt2 activation. The study proposed that exosome^MIF might have the potential to serve as a cardioprotective therapeutic agent during cancer chemotherapy.

PD-1 inhibitor inducing exosomal miR-34a-5p expression mediates the cross talk between cardiomyocyte and macrophage in immune checkpoint inhibitor-related cardiac dysfunction

Background

Immune checkpoint inhibitors (ICIs) have been an important therapeutic advancement in the field of cancer medicine. Recent reports provided greater insights into the cardiovascular adverse events, which prohibited the use of ICIs. Cardiovascular adverse events occur in different forms, such as myocarditis and cardiomyopathy, myocardial fibrosis, heart failure and pericardial disease. Cardiac aging overlapped with the occurrence of some cardiac diseases. Exosomes mediate cell–cell cross talk in cardiac diseases by transferring a variety of biomolecules, including microRNAs (miRs). miR-34a-5p is a well-known miR associated with the cardiac senescence. This study aimed to investigate whether cardiovascular adverse effects of the programmed cell death 1 (PD-1) inhibitor, a widely used ICI, were related to exosomal-transferred miR-34a-5p in cardiac senescence in a mouse model.

Methods and results

The upregulation of miR-34a-5p in cardiomyocytes induced by exosomes derived from PD-1 inhibitor–treated macrophages, accompanied by cardiac senescence, caused cardiac injury in mouse hearts. miR-34a-5p was identified as an exosomal transfer RNA to induce cardiac senescence–related injury. Inhibiting miR-34a-5p in macrophages attenuated the exosome^{PD-1 inhibitor}-induced pro-senescent effect in cardiomyocytes. TargetScan and luciferase assay showed that miR-34a-5p targeted the serine/threonine-protein phosphatase 1 regulatory subunit 10 (PNUTS) 3′-untranslated region.

Conclusions

Exosomes derived from PD-1 inhibitor–treated macrophages exerted a pro-senescent effect by modulating the miR-34a-5p/PNUTS signaling pathway. The findings might supply new targets to ameliorate cardiac injury in patients with cancer receiving PD-1 inhibitor treatment.

Uraemia-induced immune senescence and clinical outcomes in chronic kidney disease patients

BACKGROUND

Patients with chronic kidney disease (CKD) are more prone to develop premature age-related diseases. Data on immune senescence are scarce in CKD populations, except in end-stage renal disease and dialysis. We designed a longitudinal prospective study to evaluate immune senescence at different CKD stages and its influence on CKD patient outcomes.

METHODS

Clinical and biological data collections were performed on 222 patients at different CKD stages [1-2 (n = 85), 4 (n = 53) and 5 (n = 84)]. Immune senescence biomarkers were measured by cytometry on T cells (CD28, CD57, CD45RA, CD31, γH2A.X) or by quantitative polymerase chain reaction [relative telomere length (RTL)] on peripheral blood mononuclear cells and analysed according to CKD stages and outcomes.

RESULTS

CKD was associated with an increase in immune senescence and inflammation biomarkers, as follows: low thymic output (197 ± 25 versus 88 ± 13 versus 73 ± 21 CD4+CD45RA+CD31+ T cells/mm3), an increased proportion of terminally differentiated T cells (CD8+CD28-CD57+) (24 ± 18 versus 32 ± 17 versus 35 ± 19%) restricted to cytomegalovirus-positive patients, telomere shortening (1.11 ± 0.36 versus 0.78 ± 0.24 versus 0.97 ± 0.21 telomere:single copy ratio) and an increase in C-reactive protein levels [median 2.9 (range 1.8-4.9) versus 5.1 (27-9.6) versus 6.2 (3.4-10.5) mg/L]. In multivariate analysis, shorter RTL was associated with death {hazard ratio [HR] 4.12 [95% confidence interval (CI) 1.44-11.75]}. Low thymic output was associated with infections [HR 1.79 (95% CI (1.34-9.58)] and terminally differentiated CD8+ T-cell expansion with a risk of cardiovascular events [CEs; HR 4.86 (95% CI 1.72-13.72)].

CONCLUSION

CKD was associated with premature immune ageing. Each of these alterations increased the risk of specific age-related diseases, such as RTL and death, thymic function and infections and terminally differentiated CD8+ T-cell expansion and CEs.

Monitoring of CMV-specific cell-mediated immunity with a commercial ELISA-based interferon-γ release assay in kidney transplant recipients treated with antithymocyte globulin

Monitoring for cytomegalovirus (CMV)-specific cell-mediated immunity (CMV-CMI) may be useful for individualizing valganciclovir (VGCV) prophylaxis after kidney transplantation (KT). We performed a commercial ELISA-based interferon (IFN)-γ release assay (QTF-CMV) from posttransplant months 2-5 (362 points) in 120 CMV-seropositive KT recipients that received antithymocyte globulin as induction therapy and VGCV prophylaxis (median of 92 days). Forty-seven patients (39.3%) had CMV infection after discontinuation of prophylaxis. The QTF-CMV assay was reactive, nonreactive, and indeterminate in 264 (72.9%), 90 (24.9%), and 8 points (2.2%). The QTF-CMV assay at prophylaxis discontinuation exhibited suboptimal accuracy for predicting protective CMV-CMI (sensitivity: 77.4%; specificity: 34.3%; positive predictive value [PPV]: 64.1%; negative predictive value [NPV]: 50.0%), with no differences in 1-year CMV infection rates between patients with negative (nonreactive or indeterminate) or reactive results (45.8% vs 36.1%; P = .244). Specificity and PPV to predict protective CMV-CMI improved by elevating the IFN-γ cutoff value to 1.13 IU/mL (65.7% and 71.4%) and 7.0 IU/mL (85.7% and 76.2%), although NPVs decreased. The QTF-CMV assay as per manufacturer's interpretative criteria performed poorly to predict protection from CMV infection following discontinuation of VGCV prophylaxis among ATG-treated CMV-seropositive KT recipients. This performance is slightly improved by modifying the IFN-γ positivity threshold.

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.

Shorter telomere length following lung transplantation is associated with clinically significant leukopenia and decreased chronic lung allograft dysfunction-free survival

Patients with short telomeres and interstitial lung disease may have decreased chronic lung allograft dysfunction (CLAD)-free survival following lung transplantation. The relationship between post-transplant telomere length and outcomes following lung transplantation has not been characterised among all recipients, regardless of native lung disease.

This was a single-centre prospective cohort study. Consenting transplant recipients had their telomere length measured using quantitative real-time PCR assays on peripheral blood collected at the time of surveillance bronchoscopy. We assessed the association between early post-transplant telomere length (as measured in the first 100 days) and CLAD-free survival, time to clinically significant leukopenia, cytomegalovirus (CMV) viraemia, chronic kidney disease, and acute cellular rejection. We also assessed the association between rate of telomere shortening and CLAD-free survival.

Telomere lengths were available for 98 out of 215 (45.6%) recipients who underwent lung transplant during the study period (median measurement per patient=2 (interquartile range, 1–3)). Shorter telomere length was associated with decreased CLAD-free survival (hazard ratio (HR)=1.24; 95% CI=1.03–1.48; p=0.02), leukopenia requiring granulocyte colony-stimulating factor (HR=1.17, 95% CI=1.01–1.35, p=0.03), and CMV viraemia among CMV-mismatch recipients (HR=4.04, 95% CI=1.05–15.5, p=0.04). Telomere length was not associated with acute cellular rejection or chronic kidney disease. Recipients with more rapid loss in telomere length (defined as the highest tertile of telomere shortening) did not have worse subsequent CLAD-free survival than those without rapid loss (HR=1.38, 95% CI=0.27–7.01, p=0.70).

Shorter early post-transplant telomere length is associated with decreased CLAD-free survival and clinically significant leukopenia in lung transplant recipients, regardless of native lung disease.

Shorter recipient telomere length following lung transplantation is associated with clinically significant leukopenia and decreased chronic lung allograft dysfunction-free survivalhttps://bit.ly/2ytymXc

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.

Inclusion body myositis: clinical features and pathogenesis

Inclusion body myositis (IBM) is often viewed as an enigmatic disease with uncertain pathogenic mechanisms and confusion around diagnosis, classification and prospects for treatment. Its clinical features (finger flexor and quadriceps weakness) and pathological features (invasion of myofibres by cytotoxic T cells) are unique among muscle diseases. Although IBM T cell autoimmunity has long been recognized, enormous attention has been focused for decades on several biomarkers of myofibre protein aggregates, which are present in <1% of myofibres in patients with IBM. This focus has given rise, together with the relative treatment refractoriness of IBM, to a competing view that IBM is not an autoimmune disease. Findings from the past decade that implicate autoimmunity in IBM include the identification of a circulating autoantibody (anti-cN1A); the absence of any statistically significant genetic risk factor other than the common autoimmune disease 8.1 MHC haplotype in whole-genome sequencing studies; the presence of a marked cytotoxic T cell signature in gene expression studies; and the identification in muscle and blood of large populations of clonal highly differentiated cytotoxic CD8⁺ T cells that are resistant to many immunotherapies. Mounting evidence that IBM is an autoimmune T cell-mediated disease provides hope that future therapies directed towards depleting these cells could be effective.

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.

Telomere length regulators are activated in young men after pediatric kidney transplantation compared to healthy controls and survivors of childhood cancer-A cross-sectional study

Chronic diseases are known to cause premature aging and frailty. Data about telomere length and telomere length-regulating proteins after pediatric KTx are scarce. Leukocyte telomere length and gene expression level of eight telomere-binding proteins were analyzed in 20 KTx recipients, eight childhood NBL survivors, and nine healthy controls. The influence of key clinical parameters on telomere length and on regulators of telomere length was evaluated. The telomere length in the KTx recipients tended to be shorter (0.53 AU) than in the healthy controls (0.64 AU) but longer than in the NBL survivors (0.38 AU). There was no significant difference in telomere length between the NBL survivors and the KTx recipients (P = .110). The gene expression level of telomere length-preserving protein RPA1 was significantly higher in the KTx recipients than among the NBL survivors or healthy controls, while the expression of TRF2 and the tumor suppressor gene p16 was significantly higher in the KTX recipients when compared to the controls. TRF2 and TIN2 correlated significantly with hsCRP; additionally, TRF2 showed significant correlation with plasma creatinine and eGFR. KTx recipients have near to normal telomere length, but they have significantly higher gene expression levels of telomere regulatory proteins compared with healthy controls, suggesting activation of mechanisms preserving telomere length among KTx recipients. Our results suggest that declined graft function and consequent inflammatory response may have influence on telomerase activity.

Immunology of the ageing kidney

Immunosenescence involves a series of ageing-induced alterations in the immune system and is characterized by two opposing hallmarks: defective immune responses and increased systemic inflammation. The immune system is modulated by intrinsic and extrinsic factors and undergoes profound changes in response to the ageing process. Immune responses are therefore highly age-dependent. Emerging data show that immunosenescence underlies common mechanisms responsible for several age-related diseases and is a plastic state that can be modified and accelerated by non-heritable environmental factors and pharmacological intervention. In the kidney, resident macrophages and fibroblasts are continuously exposed to components of the external environment, and the effects of cellular reprogramming induced by local immune responses, which accumulate with age, might have a role in the increased susceptibility to kidney disease among elderly individuals. Additionally, because chronic kidney disease, especially end-stage renal disease, is often accompanied by immunosenescence, which affects these patients independently of age, and many kidney diseases are strongly age-associated, treatment approaches that target immunosenescence might be particularly clinically relevant.

NK Cells Contribute to the Immune Risk Profile in Kidney Transplant Candidates

Background: A previously proposed immune risk profile (IRP), based on T cell phenotype and CMV serotype, is associated with mortality in the elderly and increased infections post-kidney transplant. To evaluate if NK cells contribute to the IRP and if the IRP can be predicted by a clinical T cell functional assays, we conducted a cross sectional study in renal transplant candidates to determine the incidence of IRP and its association with specific NK cell characteristics and ImmuKnow® value.

Material and Methods: Sixty five subjects were enrolled in 5 cohorts designated by age and dialysis status. We determined T and NK cell phenotypes by flow cytometry and analyzed multiple factors contributing to IRP.

Results: We identified 14 IRP+ [CMV seropositivity and CD4/CD8 ratio < 1 or being in the highest quintile of CD8+ senescent (28CD–/CD57+) T cells] individuals equally divided amongst the cohorts. Multivariable linear regression revealed a distinct IRP+ group. Age and dialysis status did not predict immune senescence in kidney transplant candidates. NK cell features alone could discriminate IRP– and IRP+ patients, suggesting that NK cells significantly contribute to the overall immune status in kidney transplant candidates and that a combined T and NK cell phenotyping can provide a more detailed IRP definition. ImmuKnow® value was negatively correlated to age and significantly lower in IRP+ patients and predicts IRP when used alone or in combination with NK cell features.

Conclusion: NK cells contribute to overall immune senescence in kidney transplant candidates.

End-Stage Renal Disease-Associated Gut Bacterial Translocation: Evolution and Impact on Chronic Inflammation and Acute Rejection After Renal Transplantation

Chronic inflammation in end-stage renal disease (ESRD) is partly attributed to gut bacterial translocation (GBT) due to loss of intestinal epithelium integrity. Increased levels of circulating lipopolysaccharide (LPS) –a surrogate marker of GBT– contribute to maintain a chronic inflammatory state. However, circulating LPS can be neutralized by lipoproteins and transported to the liver for elimination. While ESRD-associated GBT has been widely described, less is known about its changes and impact on clinical outcome after kidney transplantation (KT). One hundred and forty-six renal transplant recipients with serum samples obtained immediately before and 1 year after transplantation (1-Year post KT) were included. Intestinal epithelium integrity (iFABP), total LPS (by measuring 3-hydroxymyristate), LPS activity (biologically active LPS measured by the LAL assay), inflammatory biomarkers (sCD14 and cytokines), lipoproteins and LPS-binding proteins (LBP and phospholipid transfer protein [PLTP] activity) were simultaneously measured. At 1-Year post KT, iFABP decreased but remained higher than in normal volunteers. Total LPS concentration remained stable while LPS activity decreased. Inflammation biomarkers decreased 1-Year post KT. We concomitantly observed an increase in lipoproteins. Higher sCD14 levels before transplantation was associated with lower incidence of acute rejection. Although GBT remained stable after KT, the contemporary increase in lipoproteins could bind circulating LPS and contribute concomitantly to neutralization of LPS activity, as well as improvement in ESRD-associated chronic inflammation. Chronic exposure to LPS in ESRD could promote endotoxin tolerance and explain why patients with higher pre-transplant sCD14 are less prompt to develop acute rejection after transplantation.

Highly differentiated cytotoxic T cells in inclusion body myositis

Inclusion body myositis is a late onset treatment-refractory autoimmune disease of skeletal muscle associated with a blood autoantibody (anti-cN1A), an HLA autoimmune haplotype, and muscle pathology characterized by cytotoxic CD8+ T cell destruction of myofibres. Here, we report on translational studies of inclusion body myositis patient muscle compared with a diverse set of other muscle disease samples. Using available microarray data on 411 muscle samples from patients with inclusion body myositis (n = 40), other muscle diseases (n = 265), and without neuromuscular disease (normal, n = 106), we identified a signature of T-cell cytotoxicity in inclusion body myositis muscle coupled with a signature of highly differentiated CD8 T-cell effector memory and terminally differentiated effector cells. Further, we examined killer cell lectin-like receptor G1 (KLRG1) as a marker of this population of cells, demonstrated the correlation of KLRG1 gene expression with lymphocyte cytotoxicity across 28 870 human tissue samples, and identified the presence of KLRG1 on pathogenic inclusion body myositis muscle invading T cells and an increase in KLRG1 expressing T cells in inclusion body myositis blood. We examined inclusion body myositis muscle T-cell proliferation by Ki67 immunohistochemistry demonstrating that diseased muscle-invading T cells are minimally or non-proliferative, in accordance with known properties of highly differentiated or terminally differentiated T cells. We found low expression of KLRG1 on infection-protective human lymphoid tissue central memory T cells and autoimmune-protective human blood regulatory T cells. Targeting highly differentiated cytotoxic T cells could be a favourable approach to treatment of inclusion body myositis.

Epidemiology, Risk Factors, and Outcomes of Opportunistic Infections after Kidney Allograft Transplantation in the Era of Modern Immunosuppression: A Monocentric Cohort Study

Epidemiology of opportunistic infections (OI) after kidney allograft transplantation in the modern era of immunosuppression and the use of OI prevention strategies are poorly described. We retrospectively analyzed a single-center cohort on kidney allograft adult recipients transplanted between January 2008 and December 2013. The control group included all kidney recipients transplanted in the same period, but with no OI. We analyzed 538 kidney transplantations (538 patients). The proportion of OI was 15% (80 and 72 patients). OI occurred 12.8 (6.0–31.2) months after transplantation. Viruses were the leading cause (n = 54, (10%)), followed by fungal (n = 15 (3%)), parasitic (n = 6 (1%)), and bacterial (n = 5 (0.9%)) infections. Independent risk factors for OI were extended criteria donor (2.53 (1.48–4.31), p = 0.0007) and BK viremia (6.38 (3.62–11.23), p < 0.0001). High blood lymphocyte count at the time of transplantation was an independent protective factor (0.60 (0.38–0.94), p = 0.026). OI was an independent risk factor for allograft loss (2.53 (1.29–4.95), p = 0.007) but not for patient survival. Post-kidney transplantation OIs were mostly viral and occurred beyond one year after transplantation. Pre-transplantation lymphopenia and extended criteria donor are independent risk factors for OI, unlike induction therapy, hence the need to adjust immunosuppressive regimens to such transplant candidates.

Monitoring of alphatorquevirus DNA levels for the prediction of immunosuppression-related complications after kidney transplantation

The replication kinetics of nonpathogenic anelloviruses belonging to the Alphatorquevirus genus (such as torque teno virus) might reflect the overall state of posttransplant immunosuppression. We analyzed 221 kidney transplant (KT) recipients in whom plasma alphatorquevirus DNA load was quantified by real-time polymerase chain reaction at baseline and regularly through the first 12 posttransplant months. Study outcomes included posttransplant infection and a composite of opportunistic infection and/or de novo malignancy (immunosuppression-related adverse event [iRAE]). Alphatorquevirus DNA loads at month 1 were higher among patients who subsequently developed posttransplant infection (P  = .023) or iRAE (P  = .009). Likewise, those with iRAE beyond months 3 and 6 also exhibited higher peak viral loads over the preceding periods. Areas under the curve for log₁₀ alphatorquevirus DNAemia estimated by months 1 or 6 were significantly higher in patients experiencing study outcomes. Alphatorquevirus DNA loads above 3.15 and 4.56 log₁₀ copies/mL at month 1 predicted the occurrence of posttransplant infection (adjusted hazard ratio [aHR]: 2.88; 95% confidence interval [CI]: 1.13-7.36; P  = .027) and iRAE (aHR: 5.17; 95% CI: 2.01-13.33; P  = .001). In conclusion, posttransplant monitoring of plasma alphatorquevirus DNA kinetics may be useful to identify KT recipients at increased risk of immunosuppression-related complications.

Lack of Benefit and Potential Harm of Induction Therapy in Simultaneous Liver-Kidney Transplants

The number of simultaneous liver-kidney transplantations (SLKTs) and use of induction therapy for SLKT have increased recently, without much published evidence, especially in the context of maintenance immunosuppression containing tacrolimus (TAC) and mycophenolic acid (MPA). We queried the Organ Procurement and Transplant Network registry for SLKT recipients maintained on TAC/MPA at discharge in the United States for 2002-2016. The cohort was divided into 3 groups on the basis of induction type: rabbit antithymocyte globulin (r-ATG; n = 831), interleukin 2 receptor antagonist (IL2RA; n = 1558), and no induction (n = 2333). Primary outcomes were posttransplant all-cause mortality and acute rejection rates in kidney and liver allografts at 12 months. Survival rates were analyzed by the Kaplan-Meier method. A propensity score analysis was used to control potential selection bias. Multivariate inverse probability weighted Cox proportional hazard and logistic regression models were used to estimate the hazard ratios (HRs) and odds ratios. Among SLKT recipients, survival estimates at 3 years were lower for recipients receiving r-ATG (P = 0.05). Compared with no induction, the multivariate analyses showed an increased mortality risk with r-ATG (HR, 1.29; 95% confidence interval [CI], 1.10-1.52; P = 0.002) and no difference in acute liver or kidney rejection rates at 12 months across all induction categories. No difference in outcomes was noted with IL2RA induction over the no induction category. In conclusion, there appears to be no survival benefit nor reduction in rejection rates for SLKT recipients who receive induction therapy, and r-ATG appears to increase mortality risk compared with no induction.

Telomeres in Interstitial Lung Disease: The Short and the Long of It

Telomeres are repetitive nucleotide sequences that cap linear chromosomes, thereby limiting progressive chromosomal shortening during cell replication. In conjunction with environmental factors, common single-nucleotide polymorphisms and rare and ultra-rare telomere-related mutations are associated with accelerated telomere shortening resulting in organ dysfunction, including interstitial lung disease (ILD). The most common telomere-related mutation-associated ILD is idiopathic pulmonary fibrosis (IPF). Up to one-third of individuals with familial IPF have shortened telomeres and/or carry a telomere-related mutation, and 1 in 10 individuals with sporadic IPF have telomere-related mutations. Regardless of ILD phenotype, individuals with short telomeres and/or known telomere-related mutations have more rapid disease progression and shorter lung transplant-free survival. Management should include initiation of antifibrotic agents for those with an IPF phenotype and early referral to a transplant center. Patients with ILD being considered for transplant should be screened for short telomeres if there is a significant family history of pulmonary fibrosis or evidence of extrapulmonary organ dysfunction associated with a short telomere syndrome. Post-transplant management of recipients with telomere-related mutations should include careful adjustment of immunosuppression regimens on the basis of bone marrow reserve. Data on the impact of shortened telomeres on post-transplant outcomes, however, remain mixed.

Parathyroid hormone and premature thymus ageing in patients with chronic kidney disease

Premature immune ageing, including thymic atrophy, is observed in patients with chronic kidney disease (CKD). Parathyroid hormone (PTH) and fibroblast growth factor 23 (FGF23), which are mineral and bone disorder (MBD)-related factors, affect immune cells and possibly cause thymic atrophy. We examined the cross-sectional association between thymic atrophy, evaluated as the number of CD3⁺CD4⁺CD45RA⁺CD31⁺ cells [recent thymic emigrants (RTE)/μL], and MBD-related factors [(serum PTH, FGF23, and alkaline phosphatase (ALP) level] in 125 patients with non-dialysis dependent CKD. Median estimated glomerular filtration rate (eGFR) was 17 mL/min/1.73 m². Older age (r = −0.46), male sex (r = −0.34), lower eGFR (r = 0.27), lower serum-corrected calcium (r = 0.27), higher PTH (r = −0.36), and higher ALP level (r = −0.20) were identified as determinants of lower number of RTE. In contrast, serum concentrations of FGF23 and phosphorus were not correlated with RTE. Multivariate non-linear regression analysis indicated a negative association between serum PTH and log-transformed RTE (P = 0.030, P for non-linearity = 0.124). However, the serum levels of FGF23 and ALP were not associated with RTE. In patients with CKD, serum PTH concentrations were related to thymic atrophy which contributes to immune abnormality.

miR‑34a derived from mesenchymal stem cells stimulates senescence in glioma cells by inducing DNA damage

Insights into the roles of microRNAs (miRNAs/miRs) in development and disease, particularly in cancer, have made miRNAs attractive tools and targets for novel therapeutic approaches in the treatment of glioma. miR‑34a, as a well‑known tumor suppressor miRNA, is closely related with cellular senescence. Mesenchymal stem cells (MSCs) are a major component of the tumor microenvironment and possess the ability to deliver exogenous miRs to glioma cells to exert anti‑tumor effects. The present study investigated whether modified MSCs with miR‑34a possess an anti‑tumor function in glioma cells. A Transwell system was used to co‑culture U87 glioma cells and MSCs overexpressing miR‑34a, and cell proliferation and senescence assessed. The expression of senescence‑related genes p53, Cdkn1a, and Cdkn2c were tested using reverse transcription‑quantitative polymerase chain reaction and protein expression levels of sirtuin 1 (SIRT1) and γ‑H2A histone family, member X were detected by western blotting. Telomerase activity of U87 cells was examined using the Telo TAGGG Telomerase PCR ELISA PLUS kit. The results demonstrated that the delivered exogenous miR‑34a from MSCs significantly decreased expression of the target gene SIRT1. In addition, the delivered miR‑34a decreased the proliferation of glioma cells and provoked the expression of senescence‑related genes p53, Cdkn1a, and Cdkn2c. In addition, upregulation of miR‑34a induced DNA damage, shortened telomere length and impaired telomerase activity. However, these pro‑senescent effects were reversed by forced SIRT1 upregulation. In conclusion, the results demonstrated a novel role for miR‑34a, inducing glioma cell senescence, whereas miR‑34a modulation of SIRT1, inducing DNA damage, is crucial for miRNA replacement therapy in glioma treatment.