Cardiovascular Risk after Kidney Transplantation: Causes and Current Approaches to a Relevant Burden

The use of digital health interventions to deliver prehabilitation in solid organ transplant recipients: are we there yet?

PURPOSE OF REVIEW

Prehabilitation, defined as preparing the body physically and psychologically for upcoming surgery is of increasing prominence in presurgical care. The aim of this review is to discuss the evidence base around prehabilitation in solid organ transplantation, the use of digital health as a tool to deliver these interventions, and consider future directions.

RECENT FINDINGS

Prehabilitation is of increasing interest as an adjunct to pretransplant care for individuals working up for solid organ transplantation. To date, research has shown that prehabilitation is acceptable and feasible; however, the literature base remains small. The majority of research has been delivered using in-person rehabilitation programmes, and the evidence base utilizing digital health as a means to deliver prehabilitation is limited.

SUMMARY

To date, the research evidence base in prehabilitation for solid organ transplantation is limited. Evidence in other surgical populations has demonstrated promising results, particularly in aerobic capacity, physical function and postoperative complications. Further high-quality randomized controlled clinical trials are required to strengthen the evidence base, understand how digital health can be harnessed and utilized to deliver multimodal prehabilitation with an aim to see how this may form part of routine care in the solid organ transplantation pathway.

The Effect of Chronic Immunosuppressive Regimen Treatment on Apoptosis in the Heart of Rats

Chronic immunosuppressive therapy is currently the only effective method to prevent acute rejection of a transplanted organ. Unfortunately, the expected effect of treatment brings a number of grave side effects, one of the most serious being cardiovascular complications. In our study, we wanted to investigate how treatment with commonly used immunosuppressive drugs affects the occurrence of programmed cardiac cell death. For this purpose, five groups of rats were treated with different triple immunosuppressive regimens. Cardiac tissue fragments were subjected to the TUNEL assay to visualize apoptotic cells. The expression of Bcl-2 protein, Bax protein, caspase 3 and caspase 9 was also assessed. This study indicates that all immunosuppressive protocols used chronically at therapeutic doses result in an increased percentage of cells undergoing apoptosis in rat heart tissue. The greatest changes were recorded in the TMG (rats treated with tacrolimus, mycophenolate mofetil and glucocorticosteroids) and CMG (rats treated with cyclosporin A, mycophenolate mofetil and glucocorticosteroids) groups. The TRG (rats treated with rapamycin, tacrolimus and glucocorticosteroids) group showed the lowest percentage of apoptotic cells. The internal apoptosis pathway was confirmed only in the TMG group; in the remaining groups, the results indicate programmed cell death via the receptor pathway.

Association between the Serum Soluble Urokinase Plasminogen Activator Receptor and Peripheral Arterial Stiffness According to the Cardio-Ankle Vascular Index in Patients Undergoing Kidney Transplantation

Background

High soluble urokinase plasminogen activator receptor (suPAR) levels are correlated with cardiovascular (CV) disease. Arterial stiffness is associated with aging-related vascular diseases and is an independent risk factor for CV morbidity and mortality. It can be measured by the cardio-ankle vascular index (CAVI). We evaluated the association between serum suPAR levels and arterial stiffness according to the CAVI in kidney transplantation (KT) recipients.

Methods

In this study, 82 patients undergoing KT were enrolled. Serum suPAR levels were analyzed using an enzyme immunoassay. The CAVI was measured using a plethysmograph waveform device, and patients with a CAVI of ≥ 9.0 were assigned to the peripheral arterial stiffness (PAS) group.

Results

Twenty KT patients (24.4%) had PAS, were of older age (p = 0.042), and had higher serum triglyceride (p = 0.023) and suPAR levels (p < 0.001) than the normal group. After adjusting for factors significantly associated with PAS by multivariate logistic regression analysis, serum suPAR levels (odds ratio [OR] 1.072, 95% confidence interval (CI) 1.023-1.123; p = 0.004) were independently associated with PAS in KT patients. The logarithmically transformed suPAR level (log-suPAR) was also positively correlated with the left or right CAVI values (all p < 0.001) from the results of the Spearman correlation analysis in KT patients.

Conclusions

Serum suPAR levels are positively associated with left or right CAVI values and are independently associated with PAS in KT patients.

Association of Serum Activin Levels with Allograft Outcomes in Patients with Kidney Transplant: Results from the KNOW-KT

INTRODUCTION

Serum activin A has been reported to contribute to vascular calcification and kidney fibrosis in chronic kidney disease. We aimed to investigate whether higher serum activin levels were associated with poor allograft outcomes in patients with kidney transplantation (KT).

METHODS

A total of 860 KT patients from KNOW-KT (Korean Cohort Study for Outcome in Patients with Kidney Transplantation) were analyzed. We measured serum activin levels pre-KT and 1 year after KT. The primary outcome was the composite of a ≥50% decline in estimated glomerular filtration rate and graft failure. Multivariable cause-specific hazard model was used to analyze association of 1-year activin levels with the primary outcome. The secondary outcome was coronary artery calcification score (CACS) at 5 years after KT.

RESULTS

During the median follow-up of 6.7 years, the primary outcome occurred in 109 (12.7%) patients. The serum activin levels at 1 year were significantly lower than those at pre-KT (488.2 ± 247.3 vs. 704.0 ± 349.6). When patients were grouped based on the median activin level at 1 year, the high-activin group had a 1.91-fold higher risk (95% CI, 1.25-2.91) for the primary outcome compared to the low-activin group. A one-standard deviation increase in activin levels as a continuous variable was associated with a 1.36-fold higher risk (95% CI, 1.16-1.60) for the primary outcome. Moreover, high activin levels were significantly associated with 1.56-fold higher CACS (95% CI, 1.12-2.18).

CONCLUSION

Post-transplant activin levels were independently associated with allograft functions as well as coronary artery calcification in KT patients.

Adverse Drug Events after Kidney Transplantation

Introduction: Kidney transplantation stands out as the optimal treatment for patients with end-stage kidney disease, provided they meet specific criteria for a secure outcome. With the exception of identical twin donor-recipient pairs, lifelong immunosuppression becomes imperative. Unfortunately, immunosuppressant drugs, particularly calcineurin inhibitors like tacrolimus, bring about adverse effects, including nephrotoxicity, diabetes mellitus, hypertension, infections, malignancy, leukopenia, anemia, thrombocytopenia, mouth ulcers, dyslipidemia, and wound complications. Since achieving tolerance is not feasible, patients are compelled to adhere to lifelong immunosuppressive therapies, often involving calcineurin inhibitors, alongside mycophenolic acid or mTOR inhibitors, with or without steroids. Area covered: Notably, these drugs, especially calcineurin inhibitors, possess narrow therapeutic windows, resulting in numerous drug-related side effects. This review focuses on the prevalent immunosuppressive drug-related side effects encountered in kidney transplant recipients, namely nephrotoxicity, post-transplant diabetes mellitus, leukopenia, anemia, dyslipidemia, mouth ulcers, hypertension, and viral reactivations (cytomegalovirus and BK virus). Additionally, other post-kidney-transplantation drugs such as valganciclovir may also contribute to adverse events such as leukopenia. For each side effect, we propose preventive measures and outline appropriate treatment strategies.

Levels of Cell-Free DNA in Kidney Failure Patients before and after Renal Transplantation

Circulating cell-free DNA (cfDNA) has diverse applications in oncological, prenatal, toxicological, cardiovascular, and autoimmune diseases, diagnostics, and organ transplantation. In particular, mitochondrial cfDNA (mt-cfDNA) is associated with inflammation and linked to early vascular ageing (EVA) in end-stage kidney failure (ESKF), which could be a noninvasive marker for graft rejection and organ damage. Plasma samples from 44 ESKF patients, of whom half (n = 22) underwent either conservative therapy (non-HD) or hemodialysis (HD) before kidney transplantation (KT). These samples were analyzed at baseline and two years after KT. cfDNA was extracted from plasma and quantified using the fluorometric method. qPCR was used to quantify and differentiate the fractions of mt-cfDNA and nuclear cfDNA (nc-cfDNA). mt-cfDNA levels in KT patients decreased significantly from baseline to two years post-KT (p < 0.0268), while levels of total cfDNA and nc-cfDNA did not differ. Depending on therapy modality (HD vs. non-HD) before KT, total cfDNA levels were higher in HD patients at both baseline (p = 0.0133) and two years post-KT (p = 0.0421), while nc-cfDNA levels were higher in HD only at baseline (p = 0.0079). Males showed a nonsignificant trend of higher cfDNA levels. Patients with assessed vascular fibrosis (p = 0.0068), either alone or in combination with calcification plus fibrosis, showed reduced mt-cfDNA post-KT (p = 0.0195). Changes in mt-cfDNA levels suggests the impact of KT on the inflammatory state of ESKF, as evidenced via its correlation with high sensitivity C-reactive protein after KT. Further studies are warranted to assess if cfDNA could serve as a noninvasive method for monitoring the response to organ transplantation and even for amelioration of EVA status per se.

Immunosuppressive Therapy and Nutritional Status of Patients after Kidney Transplantation: A Protocol for a Systematic Review

(1) Background: Kidney transplantation is widely recognized as the most effective method of treating end-stage renal disease. Immunosuppressive therapy plays a pivotal role in the treatment of kidney transplant patients, encompassing all patients (except identical twins), and is administered from organ transplantation until the end of its function. The aim of this systematic review is to identify the evidence of the association between immunosuppressive therapy and nutritional status of patients following kidney transplantation. (2) Methods: This protocol has been designed in line with Preferred Items for Systematic Reviews (PRISMA-P). Our search encompasses several databases, including MEDLINE (via PubMed), EMBASE (Elsevier), Scopus and Web of Science. We intend to include observational studies (cross-sectional, case-control, and cohort designs), randomized controlled trials (RCTs), as well as completed and ongoing non-randomized study designs. We will confine our search to studies published in English within the past decade (from inception to 17 February 2023). Qualitative studies, case studies, and conference reports will be excluded. The selection process will be done in Covidence by two independent reviewers. Data extraction will be conducted using a standardized MS Excel template version 16.0. Quality assessment of included studies will be performed using the Cochrane Risk of Bias tool for randomized trials (RoB2), or the Risk of Bias in Non-randomized Studies of Interventions (ROBINS-I) tool. Risk-of-bias plots will be generated using the web application Robvis. Relevant data that have been extracted from eligible studies will be presented in a narrative synthesis. We expect the studies to be too heterogeneous to perform subgroup analyses. (3) Conclusion: This systematic review will offer insights into the evidence regarding association between immunosuppressive therapy and nutritional status of adult patients (18 years of age or older) within the initial year following kidney transplantation. To our knowledge, there is no systematic review addressing that question.

Serum Adropin Levels and Body Mass Composition in Kidney Transplant Recipients-Are There Sex Differences?

Adropin is a secretory peptide that regulates glucose, lipid, and protein metabolism, which is closely related to obesity, insulin resistance, dyslipidemia, and atherogenesis. The serum adropin level is related to sex and depends upon nutritional preferences. This study aims to determine the association between serum adropin levels and body composition parameters in kidney transplant recipients (KTRs), especially emphasizing sex differences. Our case-control study involved 59 KTRs (28 postmenopausal women and 31 men) who were divided into two groups according to sex, and each group of those KTRs was further divided into higher or lower adropin values than the mean value in each sex group. Univariate regression showed a negative association of adropin levels with most anthropometric and body composition parameters in men's KTRs. Contrary to this, the serum adropin level was negatively associated only with phase angle in postmenopausal female KTRs. Multivariate regression showed that skeletal muscle mass and phase angle were the only negative predictors in women's KTRs, whereas in men, negative predictors were BMI and body water. These findings imply that adropin could have a different impact on metabolic homeostasis in KTRs regarding sex and could be considered a negative predictor of body composition in KTRs.

Treatment Options for Anemia in Kidney Transplant Patients: A Review

Anemia is common after kidney transplantation. The etiology may be multifactorial, such as causes of anemia in the general population and causes that are unique to the kidney transplant setting. Posttransplant anemia, particularly when severe, may be associated with adverse effects such as graft failure, mortality, and a decline in kidney function. After careful investigation, that is, having excluded or treated reversible causes of anemia, treatment of anemia in patients with a kidney transplant is based on iron supplementation or erythropoiesis-stimulating agents (ESA), although there are no specific guidelines on anemia management in this patient population. Iron therapy is often needed, but optimal and safe iron-deficiency management strategies remain to be defined. Evidence suggests that ESAs are safe and potentially associated with favorable outcomes. Better graft function has been reported with ESA use targeting hemoglobin levels higher than those recommended in the general population with chronic kidney disease and with no apparent increased risk of cardiovascular events. These results require further investigation. Data on the use of hypoxia-inducible factor inhibitors are limited. Prevention and treatment of anemia in kidney transplantation can improve patients' quality of life, life expectancy, allograft function, and survival.

Current Status Regarding Immunosuppressive Treatment in Patients after Renal Transplantation

Renal transplantation is now the best treatment for end-stage renal failure. To avoid rejection and prolong graft function, organ recipients need immunosuppressive therapy. The immunosuppressive drugs used depends on many factors, including time since transplantation (induction or maintenance), aetiology of the disease, and/or condition of the graft. Immunosuppressive treatment needs to be personalised, and hospitals and clinics have differing protocols and preparations depending on experience. Renal transplant recipient maintenance treatment is mostly based on triple-drug therapy containing calcineurin inhibitors, corticosteroids, and antiproliferative drugs. In addition to the desired effect, the use of immunosuppressive drugs carries risks of certain side effects. Therefore, new immunosuppressive drugs and immunosuppressive protocols are being sought that exert fewer side effects, which could maximise efficacy and reduce toxicity and, in this way, reduce both morbidity and mortality, as well as increase opportunities to modify individual immunosuppression for renal recipients of all ages. The aim of the current review is to describe the classes of immunosuppressive drugs and their mode of action, which are divided by induction and maintenance treatment. An additional aspect of the current review is a description of immune system activity modulation by the drugs used in renal transplant recipients. Complications associated with the use of immunosuppressive drugs and other immunosuppressive treatment options used in kidney transplant recipients have also been described.