Changes in weight during the first year after kidney transplantation

Approach and Management of Hypertension After Kidney Transplantation

Hypertension is one of the most common cardiovascular co-morbidities after successful kidney transplantation. It commonly occurs in patients with other metabolic diseases, such as diabetes mellitus, hyperlipidemia, and obesity. The pathogenesis of post-transplant hypertension is complex and is a result of the interplay between immunological and non-immunological factors. Post-transplant hypertension can be divided into immediate, early, and late post-transplant periods. This classification can help clinicians determine the etiology and provide the appropriate management for these complex patients. Volume overload from intravenous fluid administration is common during the immediate post-transplant period and commonly contributes to hypertension seen early after transplantation. Immunosuppressive medications and donor kidneys are associated with post-transplant hypertension occurring at any time point after transplantation. Transplant renal artery stenosis (TRAS) and obstructive sleep apnea (OSA) are recognized but common and treatable causes of resistant hypertension post-transplantation. During late post-transplant period, chronic renal allograft dysfunction becomes an additional cause of hypertension. As these patients develop more substantial chronic kidney disease affecting their allografts, fibroblast growth factor 23 (FGF23) increases and is associated with increased cardiovascular and all-cause mortality in kidney transplant recipients. The exact relationship between increased FGF23 and post-transplant hypertension remains poorly understood. Blood pressure (BP) targets and management involve both non-pharmacologic and pharmacologic treatment and should be individualized. Until strong evidence in the kidney transplant population exists, a BP of <130/80 mmHg is a reasonable target. Similar to complete renal denervation in non-transplant patients, bilateral native nephrectomy is another treatment option for resistant post-transplant hypertension. Native renal denervation offers promising outcomes for controlling resistant hypertension with no significant procedure-related complications. This review addresses the epidemiology, pathogenesis, and specific etiologies of post-transplant hypertension including TRAS, calcineurin inhibitor effects, OSA, and failed native kidney. The cardiovascular and survival outcomes related to post-transplant hypertension and the utility of 24-h blood pressure monitoring will be briefly discussed. Antihypertensive medications and their mechanism of actions relevant to kidney transplantation will be highlighted. A summary of guidelines from different professional societies for BP targets and antihypertensive medications as well as non-pharmacological interventions, including bilateral native nephrectomy and native renal denervation, will be reviewed.

Early Weight Gain After Transplantation Can Cause Adverse Effect on Transplant Kidney Function

BACKGROUND

The outcomes of kidney transplant recipients with increased body mass index (BMI) remain controversial. We studied the relationship between changes in BMI and kidney transplant function, especially during the first year after transplantation.

METHODS

We performed an observational cohort study of all kidney transplant recipients at our center from March 2009 to June 2014 to determine whether changes in BMI were associated with kidney transplant function, as measured by estimated glomerular filtration rate (eGFR). Recipient BMI and eGFR were calculated pre-transplant and at 1, 3, 6, 9, and 12 postoperative months (POM) after transplantation. The correlation between changes in BMI and eGFR was then evaluated.

RESULTS

Eighty-one patients were studied. There was a strong negative correlation between changes in BMI and eGFR from pre-transplant to POM 1 (correlation coefficient, -0.406; P < .0001) and from POM 1 to POM 3 (r = -0.324, P = .004).

CONCLUSIONS

We found that increased BMI caused a significant decline in renal function as measured by eGFR, especially in the initial 3 months after kidney transplantation.

Incidence of Diabetes Mellitus After Kidney Transplantation in Slovakia: Multicentric, Prospective Analysis

BACKGROUND

The incidence rate of post-transplant diabetes mellitus (PTDM) after kidney transplantation (KT) is 5% to 40%. The objective of this analysis was to identify the risk factors of PTDM after KT in the Slovak Republic (SR).

METHODS

In the group of 133 patients/non-diabetics, we identified the risk factors of PTDM in the monitored period of 12 months from transplantation.

RESULTS

The incidence of PTDM in the SR in 2014 was 38.3%. By logistic regression, we discovered that the age at the time of KT [odds ratio, 1.0885; 95% CI, 1.0222-1.1592; P = .0082], the value of body mass index (BMI) at the time of KT [odds ratio, 1.4606; 95% CI, 1.0099-2.1125; P = .0442], and the value of insulin resistance index (homeostatic model assessment for insulin resistance) at the time of KT [odds ratio, 2.5183; 95% CI, 1.7119-3.4692; P < .0001] represented predictive factors of PTDM. The independent risk factors of PTDM in our group were age at the time of KT of more than 60 years [HR 0.3871; 95% CI 0.1659-1.7767; P = .0281], waist circumference at the time of KT in men more than 94 cm and in women more than 80 cm [HR, 3.4833; 95% CI, 1.2789-9.4878 (P = .0146)], BMI at the time of KT [HR 3.0011; 95% CI 1.0725-8.3977 (P = .0363)], and triacylglycerols at the time of KT more than 1.7 mmol/L [HR, 2.9763; 95% CI, 1.0141-8.7352; P = .0471].

CONCLUSIONS

In the group of Slovak patients after kidney transplantation, the dominating risk factor for PTDM development was insulin resistance prior to KT.

Weighted Genetic Risk Scores and Prediction of Weight Gain in Solid Organ Transplant Populations

Background

Polygenic obesity in Solid Organ Transplant (SOT) populations is considered a risk factor for the development of metabolic abnormalities and graft survival. Few studies to date have studied the genetics of weight gain in SOT recipients. We aimed to determine whether weighted genetic risk scores (w-GRS) integrating genetic polymorphisms from GWAS studies (SNP group#1 and SNP group#2) and from Candidate Gene studies (SNP group#3) influence BMI in SOT populations and if they predict ≥10% weight gain (WG) one year after transplantation. To do so, two samples (n_A = 995, n_B = 156) were obtained from naturalistic studies and three w-GRS were constructed and tested for association with BMI over time. Prediction of 10% WG at one year after transplantation was assessed with models containing genetic and clinical factors.

Results

w-GRS were associated with BMI in sample A and B combined (BMI increased by 0.14 and 0.11 units per additional risk allele in SNP group#1 and #2, respectively, p-values<0.008). w-GRS of SNP group#3 showed an effect of 0.01 kg/m² per additional risk allele when combining sample A and B (p-value 0.04). Models with genetic factors performed better than models without in predicting 10% WG at one year after transplantation.

Conclusions

This is the first study in SOT evaluating extensively the association of w-GRS with BMI and the influence of clinical and genetic factors on 10% of WG one year after transplantation, showing the importance of integrating genetic factors in the final model. Genetics of obesity among SOT recipients remains an important issue and can contribute to treatment personalization and prediction of WG after transplantation.

Oxidative stress is associated with weight gain in recipients at 12-months following kidney transplantation

OBJECTIVE

Weight gain after kidney transplantation (Tx) is considered a risk factor for poor outcomes. Increased oxidative stress is associated with not only chronic renal disease and Tx, but also obesity and cardiovascular disease. The aim of this pilot study was to test whether oxidative stress is related to weight gain at 12-months after kidney Tx and to obtain preliminary insight into potential mechanisms involved.

DESIGN & METHODS

Recipients (n=33) were classified into two groups; weight loss and weight gain, based on their weight changes at 12-months post-transplant. Total antioxidant capacity (TAOC) and lipid peroxidation (TBARS) were measured to evaluate oxidative stress from plasma at baseline and 12-months. A secondary data analysis was conducted to identify potential gene regulation.

RESULTS

Seventeen recipients lost (-6.63±5.52kg), and sixteen recipients gained weight (8.94±6.18kg). TAOC was significantly decreased at 12-months compared to baseline for the total group, however, there was no significant difference between groups at either time point. TBARS was higher in weight gain group, at both time points, and it was significantly higher at 12-months (p=0.012). Gene expression profiling analysis showed that 7 transcripts annotated to reactive oxygen species related genes in adipose tissue were expressed significantly lower in weight gain group at baseline, which might be a negative feedback mechanism to reduce oxidative stress.

CONCLUSION

These results may indicate that elevated oxidative stress (TBARS) is associated with weight gain after kidney Tx and that incorporating early clinical prevention strategies known to decrease oxidative stress could be recommended.

A Pilot Study of Demographic and Dopaminergic Genetic Contributions to Weight Change in Kidney Transplant Recipients

Kidney transplant recipients often experience a significant amount of weight gain in the first year post-transplantation. While demographic factors such as age, race, and sex have been associated with weight gain in this population, these factors do not explain all of the variability seen. A number of studies have suggested that genetics also plays a critical role in weight changes. Recently, alterations in the activity of the neurotransmitter dopamine have been associated with weight change, and gene expression studies in kidney transplant recipients have supported this association. The purpose of this pilot study is to first examine the feasibility and methodology, and then to examine the associations of age, race, sex, and genotype for 13 SNPs and 3 VNTRs in 9 dopaminergic pathway genes (ANKK1, DRD2, DRD3, DRD4, SLC6A3/DAT1, MAOA, MAOB, COMT, CPE) for associations with percent weight change at 12 months post-transplantation. Seventy kidney transplant recipients had demographic and clinical data collected as a part of a larger observational study. DNA was extracted from repository buffy coat samples taken at the time of transplant, and genotyped using Taqman and PCR based methods. Three SNPs were independently associated with percent weight change: ANKK1 rs1800497 (r = -0.28, p = 0.05), SLC6A3/DAT1 rs6347 (p = 0.046), and CPE rs1946816 (p = 0.028). Stepwise regression modelling confirmed the combined associations of age (p = 0.0021), DRD4 VNTR 4/5 genotype (p = 0.0074), and SLC6A3/DAT1 rs6347 CC genotype (p = 0.0009) and TT genotype (p = 0.0004) with percent weight change in a smaller sample (n = 35) of these kidney transplant recipients that had complete genotyping. These associations indicate that there may be a genetic, and an age component to weight changes post transplantation.

Pre-transplant predictors of one yr weight gain after kidney transplantation

Clinically useful predictors of weight gain could be used to reduce the epidemic of post-kidney transplant obesity and resulting co-morbidities. The purpose of this study was to identify predictors of weight gain at 12 months following kidney transplant in a cohort of 96 recipients. Demographic, clinical, and environmental data were obtained at transplant and 12 months. Descriptive, correlational, and Bayesian network analysis were used to identify predictors. For the 52 (55.9%) recipients who gained weight, the average amount gained was 9.18 ± 6.59 kg. From the 15 baseline factors that met inclusion criteria, Bayesian network modeling identified four baseline predictors for weight gain: younger age, higher carbohydrate consumption, higher trunk fat percentage, and higher perception of mental health quality of life. Three are modifiable through either pre- or immediate post-transplant clinical intervention programs.

Expression levels of obesity-related genes are associated with weight change in kidney transplant recipients

Background

The aim of this study was to investigate the association of gene expression profiles in subcutaneous adipose tissue with weight change in kidney transplant recipients and to gain insights into the underlying mechanisms of weight gain.

Methodology/Principal Findings

A secondary data analysis was done on a subgroup (n = 26) of existing clinical and gene expression data from a larger prospective longitudinal study examining factors contributing to weight gain in transplant recipients. Measurements taken included adipose tissue gene expression profiles at time of transplant, baseline and six-month weight, and demographic data. Using multivariate linear regression analysis controlled for race and gender, expression levels of 1553 genes were significantly (p<0.05) associated with weight change. Functional analysis using Gene Ontology and Kyoto Encyclopedia of Genes and Genomes classifications identified metabolic pathways that were enriched in this dataset. Furthermore, GeneIndexer literature mining analysis identified a subset of genes that are highly associated with obesity in the literature and Ingenuity pathway analysis revealed several significant gene networks associated with metabolism and endocrine function. Polymorphisms in several of these genes have previously been linked to obesity.

Conclusions/Significance

We have successfully identified a set of molecular pathways that taken together may provide insights into the mechanisms of weight gain in kidney transplant recipients. Future work will be done to determine how these pathways may contribute to weight gain.

The challenge of closing the diversity gap: development of Hispanic nursing faculty through a Health Resources and Services Administration Minority Faculty Fellowship Program grant

Underrepresentation of minority faculty in schools of nursing is well reported. Recently, there have been multiple initiatives from both public and private sectors to alleviate the shortage of minority faculty. This article describes how the University of Tennessee Health Science Center (UTHSC) College of Nursing took advantage of one such initiative: the Health Resources and Services Administration (HRSA) Minority Faculty Fellowship Program (MFFP) grant. This program grant provides stipends to enable health professions educational programs to increase the number of faculty who are racial and ethnic minorities underrepresented in the health professions. It enabled the college to recruit a Hispanic nurse and to assist her in preparing for a successful academic career. HRSA provided a stipend in an amount not exceeding 50% of regular faculty salary of the institution for 3 years, to be matched by the institution. Expert faculty mentored the nurse's development in the areas of pedagogy, administration and leadership, design and conduct of research, grant writing and scientific writing for publication in peer-reviewed journals, and cultural competence. Dr. Susan Jacob was the project director of the MFFP grant received by the College of Nursing at UTHSC, and Zoila Sanchez, a Cuban American, was the minority faculty fellow supported by an HRSA MFFP grant. Dr. Sanchez was the first minority faculty fellow selected from the nursing profession. Past fellows represented the other health professions such as medicine and dentistry.

Prevalence of metabolic syndrome and obesity in renal transplanted Mexican children

The purpose of the study was to evaluate the prevalence of MS and obesity in Mexican children with more than one yr post-renal transplantation. Thirty-two children transplanted between January 2004 and February 2006 were included in the study. The weight and height at the time of renal transplant were obtained. A fasting blood sample was drawn for serum creatinine, adiponectin, and complete lipid profile, and a three-h glucose tolerance test was also taken. A complete nutritional evaluation was performed including anthropometry. There was a statistically significant increase in BMI at one yr post-transplant that was maintained at two yr post-transplant. Three patients exhibited obesity and were overweight. Seventeen patients had hypertension, 14 patients had low HDL, 12 patients had hypertriglyceridemia, all had normal fasting glucose, six of them had glucose intolerance, and two had waist circumference higher than 90%. Eight patients (25%) had MS. Patients with MS had higher proportion of deceased donor grafts, acute rejection episodes, and received more methylprednisolone pulses; also they had a statistically significant higher pretransplant BMI than patients without MS. There was a significant relationship between BMI at one yr post-renal transplant and creatinine clearance estimated by Schwartz formula.