Nutritional and Metabolic Issues in Solid Organ Transplantation: Targets for Future Research

Is Intestinal Dysbiosis-Associated With Immunosuppressive Therapy a Key Factor in the Pathophysiology of Post-Transplant Diabetes Mellitus?

Post-transplant diabetes mellitus (PTDM) is one of the most common and deleterious comorbidities after solid organ transplantation (SOT). Its incidence varies depending on the organs transplanted and can affect up to 40% of patients. Current research indicates that PTDM shares several common features with type 2 diabetes mellitus (T2DM) in non-transplant populations. However, the pathophysiology of PTDM is still poorly characterized. Therefore, ways should be sought to improve its diagnosis and therapeutic management. A clear correlation has been made between PTDM and the use of immunosuppressants. Moreover, immunosuppressants are known to induce gut microbiota alterations, also called intestinal dysbiosis. Whereas the role of intestinal dysbiosis in the development of T2DM has been well documented, little is known about its impacts on PTDM. Functional alterations associated with intestinal dysbiosis, especially defects in pathways generating physiologically active bacterial metabolites (e.g., short-chain fatty acids, trimethylamine N-oxide, indole and kynurenine) are known to favour several metabolic disorders. This publication aims at discussing the potential role of intestinal dysbiosis and dysregulation of bacterial metabolites associated with immunosuppressive therapy in the occurrence of PTDM.

Weight Gain After Heart Transplantation in Adults: Systematic Review and Meta-Analysis

Gain in weight is common after heart transplantation but the magnitude of usual weight gain and whether this varies by country is unknown. We systematically reviewed all relevant studies to quantify weight change among heart transplant recipients (HTRs) in the years after transplantation and assess variation with geographic location. We searched PubMed, Cumulative Index to Nursing and Allied Health Literature, and Excerpta Medica Database databases to September 2020. Eligible studies reported adult HTRs' mean/median weight and/or body mass index (BMI) up to time of transplantation (baseline) and posttransplantation in any language. Weighted mean differences (WMDs) (95% confidence intervals [CIs]) of weight/BMI from baseline to posttransplantation were estimated using a random-effects model. Ten studies met the inclusion criteria. Pooled analysis showed weight gain of 7.1 kg (95% CI, 4.4-9.8 kg) in HTRs 12 months posttransplant, with corresponding BMI increase of 1.69 kg/m2 (95% CI, 0.83-2.55 kg/m2). Greatest weight gain at 12 months posttransplant occurred in US HTRs (WMD weight 10.42 kg, BMI 3.25 kg/m2) and least, in European HTRs (WMD weight 3.10 kg, BMI 0.78 kg/m2). In conclusion, HTRs gain substantial weight in the years after transplantation, but varying widely by geographic location.

Usability and experience testing to refine an online intervention to prevent weight gain in new kidney transplant recipients

OBJECTIVES

Weight gain in the first year following kidney transplantation increases the risk of adverse health outcomes. Currently, there is no recognized intervention available to prevent weight gain after kidney transplantation. An online kidney transplant-specific resource, entitled Exercise in Renal Transplant Online (ExeRTiOn), has been co-created by a multi-professional team, including patients, to assist with weight prevention. This study aimed to evaluate patient and health care professional usability and experience of the ExeRTiOn online resource.

DESIGN

Qualitative study utilizing 'Think-Aloud' and semi-structured interviews.

METHODS

Participants (n = 17) were purposively sampled to include new kidney transplant recipients (n = 11) and transplant health care professionals (n = 6). Kidney transplant recipient participants were from a spread of physical activity levels based on scores from the General Practice Physical Activity Questionnaire (GPPAQ). 'Think-Aloud' interviews assessed the usability of ExeRTiOn. Semi-structured interviews explored participants' experience of ExeRTiOn, weight gain, and physical activity. The data set were analysed thematically. Participant characteristics, including login data and self-reported body weight, were collected.

RESULTS

Data analyses identified valued intervention content and usability aspects which were summarized by two themes. The first theme 'You need to know how to manage yourself' included subthemes: (1) the resource filled a guidance gap, (2) expert patient content resonated, and (3) the importance of goal setting and monitoring progress. The second theme 'room for improvement' included subthemes: (2) web support and (2) content and operational change suggestions.

CONCLUSIONS

Results have allowed for identification of potential areas for resource refinement. This has facilitated iterative enhancement of ExeRTiOn in preparation for a randomized controlled feasibility trial.

Long-term dietary habits and interventions in solid-organ transplantation

Diet and nutrition are moving to the forefront of modern primary and preventive care to help address the rising burden of chronic diseases among the general population. Such a movement has yet to occur formally across the field of transplantation. We therefore looked to establish the current base of knowledge regarding diet, nutrition and solid-organ transplantation. A limited number of focused studies looking into the dietary habits of solid-organ transplant patients have been performed and many of the available studies have detailed the nutritional status in the peri-operative period. Frequently described, however, is the heavy incidence of metabolic abnormalities, such as obesity, dyslipidemia and diabetes, occurring after solid-organ transplantation. Optimistically, several studies have noted improvement in several metabolic abnormalities with the use of dietary interventions in the post-transplant period. Despite these positive results, few consensus guidelines for post-transplant diet have been established and nutritional support among transplant programs remains limited. Although there are many hurdles to implementation of detailed dietary recommendations and nutritional support for transplant patients, creating such programs and guidelines could dramatically impact long-term outcomes and burden of chronic metabolic disease for transplant recipients.

Pediatric post-transplant metabolic syndrome: new clouds on the horizon

Liver transplantation (LT) is a standard treatment for children with end-stage liver disease, standing at more than 90% survival rate after one yr, and at over a 70% survival rate after five yr. The majority of transplanted children enjoy an excellent quality of life but complications can occur in the long term, and can develop subclinically in otherwise well children; there are various underestimated nutritional and metabolic aspects, including the so-called post-transplant metabolic syndrome (PTMS). During the post-transplant period, the use of immunosuppressants, corticosteroids, calcineurin inhibitors, and the presence of risk factors, including non-alcoholic fatty liver disease (NAFLD), and kidney and bone complications have been largely implicated in PTMS development. Strategies to reduce the progression of PMTS should include careful screening of patients for diabetes, dyslipidemia, and obesity, and to support weight reduction with a carefully constructed program, particularly based on diet modification and exercise. With early identification and appropriate and aggressive management, excellent long-term health outcomes and acceptable graft survival can be achieved.

Characterizing dietary intake and physical activity affecting weight gain in kidney transplant recipients

CONTEXT

Weight gain after kidney transplantation affects 50% to 90% of kidney transplant recipients. Factors leading to weight gain in recipients are thought to include a change in lifestyle (eg, dietary intake and physical activity), age, race, sex, and immunosuppressant medications.

OBJECTIVE

To examine dietary intake and physical activity of kidney transplant recipients at baseline and 3 and 6 months after transplantation to identify contributing factors to weight gain.

DESIGN

Descriptive, correlational study using secondary data from a larger parent study examining genetic and environmental contributors to weight gain after kidney transplantation.

PARTICIPANTS AND SETTING

Forty-four kidney transplant recipients at a mid-South university hospital-based transplant institute who had dietary intake, physical activity, and clinical data at baseline and 3 and 6 months were included.

MAIN OUTCOME MEASURES

Dietary intake, physical activity, weight, and body mass index.

RESULTS

Mean weight gain increased by 6% from baseline to 6 months. Interestingly, dietary intake did not change significantly from baseline to 6 months. Hours of sleep per day decreased during the same period (P = .02). Dietary intake, physical activity, age, race, sex, and immunosuppression showed no significant relationship to weight gain at 6 months.

CONCLUSION

Little consideration has been given to dietary intake and physical activity of kidney transplant recipients and the effects of these variables on weight gain. Further studies with a larger sample are needed, as weight gain after transplantation is a significant risk factor for diminished long-term outcomes.

Fasting long-acting natriuretic peptide correlates inversely with metabolic syndrome in kidney transplant patients

The metabolic syndrome (MetS) is a risk factor for posttransplant diabetes mellitus, chronic graft dysfunction, graft loss, occurrence of atherosclerotic events, and patient death among kidney transplantation patients. Long-acting natriuretic peptide (LANP) is among the peptide hormones in atrial natriuretic peptide prohormone. Low levels of natriuretic peptide may lead to reduced lipolysis and excessive weight gain in obese patients. This study was undertaken to evaluate the relationship between MetS and fasting serum LANP concentration among kidney transplanted patients. Fasting blood samples were obtained from 69 kidney recipients. The MetS and its components were defined using the diagnostic criteria of the International Diabetes Federation. Fasting LANP levels were measured using a commercial enzyme immunoassay kit. The prevalence rate of MetS was 20.3% (14/69). Fasting LANP level negatively correlated with MetS among these patients (P = .010). Using univariate linear regression analysis, serum LANP values were negatively correlated with hemoglobin (r = -0.252; P = .037), and positively correlated with blood urea nitrogen (r = 0.254; P = .035) and creatinine (r = 0.311; P = .009). Multivariate forward stepwise linear regression analysis of the significant variables revealed that creatinine (R(2) change = 0.097; P = .009) was an independent predictor of fasting serum LANP concentration among kidney transplanted patients. Serum LANP concentration correlates inversely with MetS; for these patients, creatinine is an independent predictor of the serum LANP value.

Serum adiponectin levels in renal transplant recipients with and without metabolic syndrome

OBJECTIVES

Adiponectin (APN) is an adipocyte-derived protein that has anti-inflammatory, anti-atherogenic, and insulin-sensitizing effects. Lower serum APN level is associated with various inflammatory and metabolic diseases in the general population. Kidney transplant (KT) recipients are at higher risk for developing several metabolic disorders, including metabolic syndrome (MS). The aim of the current study was to assess the change of APN level in KT recipients with and without MS.

METHODS

Prevalent KT recipients followed at our hospital were enrolled for the cross-sectional study of MS. The modified Adult Treatment Panel III criteria adopted for the Asian population were used to define MS. Overnight fasting blood samples were obtained for biochemistry and APN. APN was assayed with a commercially available enzyme-linked immunosorbent assay (ELISA) kit. The simplified Modification of Diet in Renal Disease (MDRD) equation was used for the calculation of estimated glomerular filtration rate (eGFR). Univariate and multivariate logistic regression were performed to determine parameters that were associated with serum APN level.

RESULTS

A total of 271 KT recipients (male:female = 133:138), with a mean age of 52.3 ± 12.6 years, were enrolled for the study of MS. The mean duration of follow-up posttransplantation was 9.02 ± 5.91 years. MS was found in 72 of 271 KT recipients (26.6%). Patients with MS were older, had significantly higher body weight, waist circumference, serum creatinine, fasting plasma sugar, and hemoglobin A1c, but lower serum APN level and eGFR than did patients without MS. Univariate logistic regression revealed the following variables were associated with APN level: MS, gender, body weight, body height, waist circumference, body mass index, serum creatinine, fasting blood sugar, triglyceride, high-density lipoprotein (HDL) cholesterol, and eGFR. Multivariate analysis revealed that gender, body weight, serum creatinine, triglyceride, and HDL cholesterol were associated with APN level.

CONCLUSION

Our results revealed that KT recipients with MS had significantly lower serum APN levels, even in the presence of lower eGFR, than those without MS.

Hypoadiponectinemia correlates with metabolic syndrome in kidney transplantation patients

Serum adiponectin values correlate inversely with the presence of metabolic syndrome (MS). This study was undertaken to evaluate the relationship between MS and fasting serum adiponectin concentrations in 55 kidney transplantation patients. MS and its components were defined using the diagnostic criteria of the International Diabetes Federation. Thirteen subjects (23.6%) with MS showed negative correlations with adiponectin levels (P = .035), which also negatively correlated with a number of MS criteria (P = .015). Univariate linear regression analysis showed, serum adiponectin values to negatively correlate with waist circumference (r = -0.367; P = .006), body mass index (r = -0.306; P = .023), and body fat mass (r = -0.373; P = .005). Multivariate forward stepwise linear regression analysis of the significant variables revealed that body fat mass (R(2) change = 0.139; P = .035) and waist circumference (R(2) change = 0.067; P = .041) were independent predictors of fasting serum adiponectin concentrations. Thus, serum adiponectin concentrations correlated inversely with MS. Body fat mass and waist circumference were independent predictors of serum adiponectin values in kidney transplant patients.

Hyperleptinemia positively correlated with metabolic syndrome in renal transplant recipients

OBJECTIVE

Our aim was to evaluate the relationship between metabolic syndrome and fasting serum leptin concentration in renal transplant recipients.

PATIENTS AND METHODS

Fasting blood samples were obtained from 55 renal transplant recipients. Metabolic syndrome and its components were defined using the diagnostic criteria of the International Diabetes Federation.

RESULTS

Thirteen patients (23.6%) had metabolic syndrome. Fasting leptin concentrations were positively correlated with metabolic syndrome (p=0.003). Univariate linear regression analysis indicated fasting serum leptin values were positively correlated with waist circumference (r=0.284; p=0.036), body mass index (r=0.358; p=0.007), body fat mass (r=0.610; p<0.001), triglycerides (r=0.268; p=0.048), high-sensitivity C-reactive protein (hs-CRP) (r=0.377; p=0.005), triceps skinfold (r=0.335; p=0.012), and mid-arm fat area (r=0.351; p=0.009). Multivariate forward stepwise linear regression analysis of the significant variables revealed that body fat mass (R2 change=0.373; p<0.001) and hs-CRP (R2 change=0.045; p=0.049) were the independent predictors of fasting serum leptin concentration.

CONCLUSION

Serum leptin concentration correlates positively with metabolic syndrome in renal transplant recipients.

Long-Term Impact of Cyclosporin Reduction with MMF Treatment in Chronic Allograft Dysfunction: REFERENECE Study 3-Year Follow Up

Calcineurin inhibitor (CNI) toxicity contributes to chronic allograft nephropathy (CAN). In the 2-year, randomized, study, we showed that 50% cyclosporin (CsA) reduction in combination with mycophenolate mofetil (MMF) treatment improves kidney function without increasing the risk for graft rejection/loss. To investigate the long-term effect of this regimen, we conducted a follow up study in 70 kidney transplant patients until 5 years after REFERENCE initiation. The improvement of kidney function was confirmed in the MMF group but not in the control group (CsA group). Four graft losses occurred, 2 in each group (graft survival in the MMF group 95.8% and 90.9% in control group). One death occurred in the control group. There was no statistically significant difference in the occurrence of serious adverse events or acute graft rejections. A limitation is the weak proportion of patient still remaining within the control group. On the other hand, REFERENCE focuses on the CsA regimen while opinions about the tacrolimus ones are still debated. In conclusion, CsA reduction in the presence of MMF treatment seems to maintain kidney function and is well tolerated in the long term.