Comparison of markers of appetite and inflammation between hemodialysis patients with and without failed renal transplants

The prevalence and clinical significance of loss of appetite in older patients with chronic kidney disease

PURPOSE

To determine predictors of loss of appetite among older adults with chronic kidney disease (CKD).

METHODS

Demographic and clinical data, and scores of comprehensive geriatric assessment parameters of patients who were ≥ 60 years old and have CKD according to an estimated glomerular filtration rate (eGFR) of < 60 mL/min/1.73 m2 were reviewed. Loss of appetite was defined as a score of ≤ 28 in The Council on Nutrition Appetite Questionnaire. Logistic regression analysis was performed to determine the predictors of loss of appetite.

RESULTS

Of the 398 patients included, 288 (72%) were female, and the mean age was 80 ± 7. Loss of appetite was present in 233 (59%) of patients. The frequency appeared to significantly increase with a decline in eGFR to < 45 mL/min/1.73 m2 (p < 0.05). Older age, female sex, the presence of frailty, and higher scores of Insomnia Severity Index and geriatric depression scale-15 were associated with a higher risk of loss of appetite, while longer time on education, higher levels of hemoglobin, eGFR, and serum potassium, and higher scores of handgrip strength, Tinetti gait and balance test, basic and instrumental activities of daily living, and Mini-Nutritional risk Assessment (MNA) were associated with a lower risk (p < 0.05). Associations between insomnia severity and geriatric depression remained significant after adjustment for all parameters including the MNA score.

CONCLUSION

Loss of appetite is quite common in older adults with CKD and may be a sign of poor health status in older people with CKD. There is a close relationship between loss of appetite and insomnia or depressive mood.

Pathophysiological mechanisms leading to muscle loss in chronic kidney disease

Loss of muscle proteins is a deleterious consequence of chronic kidney disease (CKD) that causes a decrease in muscle strength and function, and can lead to a reduction in quality of life and increased risk of morbidity and mortality. The effectiveness of current treatment strategies in preventing or reversing muscle protein losses is limited. The limitations largely stem from the systemic nature of diseases such as CKD, which stimulate skeletal muscle protein degradation pathways while simultaneously activating mechanisms that impair muscle protein synthesis and repair. Stimuli that initiate muscle protein loss include metabolic acidosis, insulin and IGF1 resistance, changes in hormones, cytokines, inflammatory processes and decreased appetite. A growing body of evidence suggests that signalling molecules secreted from muscle can enter the circulation and subsequently interact with recipient organs, including the kidneys, while conversely, pathological events in the kidney can adversely influence protein metabolism in skeletal muscle, demonstrating the existence of crosstalk between kidney and muscle. Together, these signals, whether direct or indirect, induce changes in the levels of regulatory and effector proteins via alterations in mRNAs, microRNAs and chromatin epigenetic responses. Advances in our understanding of the signals and processes that mediate muscle loss in CKD and other muscle wasting conditions will support the future development of therapeutic strategies to reduce muscle loss.

Leptin and ghrelin in chronic kidney disease: their associations with protein-energy wasting

BACKGROUND

This study aimed to evaluate plasma concentrations of leptin and total ghrelin in children with chronic kidney disease (CKD) and assess their roles in protein-energy wasting (PEW).

METHODS

This study consisted of three different CKD populations [CKD group (20 patients with non-dialysis CKD), dialysis group (39 patients on dialysis), and kidney transplant (KTx) group (35 KTx recipients)] and control group (18 healthy children). Plasma leptin and total ghrelin levels were measured. Multi-frequency bioimpedance analysis was used for the assessment of fat and lean mass. PEW was defined using criteria including body mass, muscle mass, growth, serum albumin level, and protein intake.

RESULTS

While plasma leptin levels did not differ among the study groups, total ghrelin levels were significantly higher in the dialysis group (P < 0.001). Seven dialysis patients (18%) and one CKD patient (5%) but none of the KTx recipients met the criteria of PEW. Dialysis patients with PEW had lower plasma leptin levels compared to their counterparts (P = 0.018); however, total ghrelin levels did not differ between the two groups (P = 0.10). Low leptin level in dialysis patients was independently associated with lower fat mass index (P < 0.001) and lower height-specific SD scores of BMI (P = 0.019).

CONCLUSIONS

PEW is prevalent in dialysis patients. Low levels of leptin seem to be associated with PEW. Our result suggests that low leptin levels may be a consequence rather than a cause of PEW. Longitudinal studies are required to investigate this complex relationship between leptin and PEW in pediatric dialysis patients.

Transplant Patients With Failing Renal Allografts

Progress in patient care and immunosuppressive medications has resulted in improved allograft survival in the early posttransplant period; however, substantial graft loss continues in the long term. Therefore, the number of dialysis patients with failed allografts is increasing progressively. These patients have a worse prognosis than naive dialysis patients. Cardiovascular causes are the leading cause of death, followed by infections and malignancies. Delay in return to dialysis, a chronic inflammatory state, infections, and cancer are contributing factors to mortality, whereas type of dialysis modality does not have a significant effect on outcomes. Graft nephrectomy is a risky operation; therefore, it should not be a routine procedure and rather should be performed only when indicated. Overall, most grafts are left in place, whereas graft nephrectomy is performed in atients with graft intolerance syndrome. Management of immunosuppressive drugs after graft failure is controversial. In the case of maintaining immunosuppression, there is increased risk of infections, cardiovascular diseases, and malignancies and also steroid-related adverse effects. On the other hand, discontinuation of immunosuppressants may result in loss of residual allograft function and also acute graft inflammation. Together, immunosuppressive drugs are almost always discontinued in these patients because of their inherent adverse effects. Considering the sequence of cessation, first antiproliferative drugs are stopped, followed by calcineurin inhibitors, and finally steroids. Because many studies show a clear survival benefit, every attempt should be made for a retransplant in patients with failed renal allografts.

Age modifies the association between serum obestatin, appetite and nutritional status in maintenance hemodialysis patients

BACKGROUND/OBJECTIVES

Increased age is strongly associated with anorexia and protein-energy wasting (PEW) in maintenance hemodialysis (MHD) population. We hypothesized that the association of obestatin, a recently discovered anorexigenic gut hormone, with appetite and nutritional status differs by age groups.

SUBJECTS/METHODS

We performed a cross-sectional study on 261MHD patients. Obestatin, acyl-ghrelin, markers of inflammation (CRP, IL-6, TNF-α) and nutrition (self-reported appetite, dietary intake, biochemical nutritional parameters, and body composition) were measured.

RESULTS

Obestatin was associated with appetite in multivariate analyses even after controlling for such confounders as lean body mass (LBM), IL-6 and acyl-ghrelin in patients younger than 71 years. For each ng/ml increase in obestatin levels, the odds for diminished appetite was 0.75 (95% CI: 0.59-0.96). However, these associations were not observed in patients 71 years and older. Multivariable logistic regression models (including appetite) also showed increasing odds for PEW (defined by ESPEN consensus-based criteria for the diagnosis of malnutrition) across increasing serum obestatin levels (OR: 1.51, 95% CI: 1.05-2.18) in patients 71 years and older. However, after lean body mass (LBM) was added to this model, the association between obestatin and malnutrition was abolished (OR: 1.26, 95% CI: 0.83-1.91).

CONCLUSIONS

The association between serum obestatin, appetite and PEW differs depending on age in MHD patients. A positive link with appetite exists in patients younger than 71 years, whereas this relationship disappears by the age of 71. In older MHD patients, obestatin is associated with PEW through mechanisms related to LBM, but not to appetite.

Malnutrition in Chronic Kidney Disease

Patients with chronic kidney disease are at substantial risk for malnutrition, characterized by protein energy wasting and micronutrient deficiency. Studies show a high prevalence rate of malnutrition in both children and adults with chronic kidney disease. Apart from abnormalities in growth hormone-insulin like growth factor axis, malnutrition also plays a role in the development of stunted growth, commonly observed in children with chronic kidney disease. The pathogenic mechanisms of malnutrition in chronic kidney disease are complex and involve an interplay of multiple pathophysiologic alterations including decreased appetite and nutrient intake, hormonal derangements, metabolic imbalances, inflammation, increased catabolism, and dialysis related abnormalities. Malnutrition increases the risk of morbidity, mortality and overall disease burden in these patients. The simple provision of adequate calorie and protein intake does not effectively treat malnutrition in patients with chronic kidney disease owing to the intricate and multifaceted derangements affecting nutritional status in these patients. A clear understanding of the pathophysiologic mechanisms involved in the development of malnutrition in chronic kidney disease is necessary for developing strategies and interventions that are effective, and capable of restoring normal development and mitigating negative clinical outcomes. In this article, a review of the pathophysiologic mechanisms of malnutrition in chronic kidney disease is presented.

APPETITE PREDICTS INTAKE AND NUTRITIONAL STATUS IN PATIENTS RECEIVING PERITONEAL DIALYSIS

BACKGROUND

Sub-optimal nutrition status is common amongst patients receiving peritoneal dialysis (PD) and leads to poor clinical outcome. This population experiences multi-factorial challenges to achieving optimal nutritional status, particularly driven by inadequate intake.

OBJECTIVES

The aim of this investigation was to identify factors associated with inadequate protein intake and sub-optimal nutritional status in patients undergoing PD.

DESIGN/PARTICIPANTS

This was a cross-sectional study of 67 adult patients receiving PD (mean age 59 ± 14 years; 57% male) within a single centre. Participants were consecutively recruited and interviewed by renal dietitians, collecting: Subjective Global Assessment (SGA); quality of life (using EQ-5D); dietary intake (via dietary interview); and appetite (using Appetite and Diet Assessment Tool). Participant demographics were obtained via survey or medical charts. Main outcome measures were inadequate dietary protein intake (<1.1 g/kg adjusted body weight/day) and malnutrition (as defined by SGA rating B or C).

RESULTS

Overall, 15 (22%) patients were malnourished and 29 (43%) had inadequate protein intake. Poor appetite (anorexia) was reported in 62% (18/29) of participants with inadequate protein malnourished patients reported anorexia versus 12 (23%) of the well-nourished patients (p = 0.0001).

CONCLUSION

Anorexia was a key risk factor for inadequate protein intake and malnutrition in patients undergoing PD. These findings highlight a need to closely monitor patients with appetite disturbances.

Transplant nephrectomy: histologic findings—a single center study

AIMS

To identify the histopathological features of transplant nephrectomy (TN) specimens.

METHODS

We performed retrospective analysis of 73 nephrectomies to review the histopathology in detail and correlate the Banff grading characteristics of TN specimens with time post engraftment and clinical features. Retrospective data on donor-specific antibodies (DSA) were also collected.

RESULTS

The majority of patients who had TN in less than 3 months posttransplant (n = 20; median time to TN: 4 days) had hemorrhagic infarction; 7 patients (35%) had grade 3 acute rejection (AR). Patients who had TN later than 3 months posttransplant (n = 53; median time to TN: 67 months) had AR, grade 2B (21%) and 3 (43%), coexisting with advanced vascular injury in the form of interstitial hemorrhage, extensive interstitial fibrosis and tubular atrophy (IF/TA) as well as the presence of DSAs. Overall, the majority of patients without DSA pre-TN developed DSA post-TN.

CONCLUSIONS

Our data revealed extensive inflammation and ongoing immunologic activity in a subset of patients with a failed graft. Careful and individualized approach based on clinical and laboratory data should guide the decision for transplant nephrectomy.

Elevated resistin levels are associated with inflammation in hemodialysis patients with failed renal allografts

BACKGROUND

Resistin is an adipocytokine, associated with insulin resistance and inflammation. The aim of this study is to evaluate the levels of serum resistin levels and other markers of inflammation in hemodialysis (HD) patients with failed renal allografts.

METHODS

Sixty-nine HD patients with failed renal allografts and 98 never transplanted (naive) HD patients and also 21 healthy controls were included in the study. Serum levels of various biochemical parameters as well as resistin, IL-6, TNF-α and hs-CRP as biochemical markers of inflammation, were measured.

RESULTS

Serum resistin levels in patients with failed renal allografts (4.80 ± 2.06 ng/mL) were significantly higher than those of the naive HD patients (3.44 ± 1.48 ng/mL) and healthy controls (0.95 ± 0.38 ng/mL; p<0.001). Patients with failed transplants were also characterized by higher TNF-alpha levels (96.8 ± 131.3 pg/mL vs. 40.9 ± 25.4 pg/mL; p<0.001) and IL-6 levels (83.9 ± 150.9 pg/mL vs. 14.6 ± 14.4 pg/mL; p<0.001) as compared to naive HD patients. Serum hs-CRP levels in patients with failed renal allografts (9.33 ± 11.86 mg/L) were significantly higher than those of the naive HD patients (1.26 ± 1.71 mg/L) and healthy controls (2.12 ± 1.82 mg/L; p<0.001). Serum albumin levels in patients with failed transplants (3.84 ± 0.47 g/dL) were lower as compared to never transplanted HD patients (4.13 ± 0.33 g/dL) and healthy controls (4.53 ± 0.40 g/dL; p<0.001). There was a positive correlation between serum resistin and TNF-alpha levels (r = 0.486, p<0.001).

CONCLUSIONS

Serum resistin levels are increased in HD patients with failed renal allografts very probably reflecting an allograft-induced chronic inflammatory state.

Protein energy wasting and transplantation

In patients with advanced renal failure or those undergoing dialysis, protein energy wasting (PEW) is a frequently occurring complication that is associated with increased cardiovascular morbidity and mortality. Fewer data are available for patients after transplantation. In this article, the available data on nutritional status after kidney transplantation is reviewed. It was also found that signs of PEW and microinflammation in patients undergoing kidney transplantation are associated with both impaired transplantation outcomes and decreased patient survival. Data are lacking on nutritional support and outcomes after transplantation. Only 1 study revealed a possible relationship between healthier eating habits and better outcomes in patients who have undergone transplantation. More data support the notion that sufficient physical exercise improves graft survival and patient outcome after kidney transplantation. Future studies on nutritional support in patients with signs of PEW and microinflammation immediately after transplantation could reveal whether such a strategy improves renal and patient outcomes.

Timing of return to dialysis in patients with failing kidney transplants

In the last decade, the number of patients starting dialysis after a failed kidney transplant has increased substantially. These patients appear to be different from their transplant-naïve counterparts, and so may be the timing of dialysis therapy initiation. An increasing number of studies suggest that in transplant-naïve patients, later dialysis initiation is associated with better outcomes. Very few data are available on timing of dialysis reinitiation in failed transplant recipients, and they suggest that an earlier return to dialysis therapy tended to be associated with worse survival, especially among healthier and younger patients and women. Failed transplant patients may also have unique issues such as continuation of immunosuppression versus withdrawal or the need for remnant allograft nephrectomy with regard to dialysis reinitiation. These patients may have a different predialysis preparation work-up, worse blood pressure control, higher or lower serum phosphorus levels, lower serum bicarbonate concentration, and worse anemia management. The choice of dialysis modality may also represent an important question for these patients, even though there appears to be no difference in mortality between patients starting peritoneal versus hemodialysis. Finally, failed transplant patients returning to dialysis appear to have a higher mortality rate compared with transplant-naïve incident dialysis patients, especially in the first several months of dialysis therapy. In this review, we will summarize the available data related to the timing of dialysis initiation and outcomes in failed kidney transplant patients after returning to dialysis.

Association of genetic variants of ghrelin, leptin and UCP2 with malnutrition inflammation syndrome and survival in end-stage renal disease patients

Malnutrition inflammation syndrome (MIS) is common among ESRD patients. In the present study, we have investigated the association of genetic markers associated with appetite and energy regulation with malnutrition inflammation syndrome among end-stage renal disease (ESRD) patients. Two hundred and fifty-seven patients on maintenance hemodialysis and 200 normal healthy controls were included in the study. Nutritional assessment was done by subjective global assessment scores (SGA). Genotyping of leptin-2548 G/A (rs7799039), ghrelin Leu72Met (rs696217-408 C/A), Arg51Gln (rs34911341-346 G/A) and uncoupling protein 2 (UCP2) 45 bp insertion deletion was done using PCR-RFLP. Levels of leptin and acyl ghrelin were assessed using ELISA. Leptin-2548 AA genotype was associated with twofold higher risk of disease susceptibility while UCP2 insertion-deletion heterozygotes showed protective effect. Ghrelin Gln51Gln and Met72Met genotype were associated with 3.4- and 2.5-fold higher disease susceptibility. The Met72 and Gln51 allele showed 3.3- and 2.1-fold higher susceptibility to malnutrition in severe SGA group. Further, the levels of acyl ghrelin were significantly less in severe category of malnutrition and in poor appetite group. On combined analysis, the group 2 (presence of 3-4 risk alleles) showed 1.5- and twofold higher susceptibility to disease and malnutrition, respectively. On docking analysis, it was observed that higher receptor binding energy was associated with the mutant form of ghrelin (Gln51). Moderate and severe SGA were associated with 2.2- and 4.1-fold higher death hazard. Our study suggests that ghrelin may be major marker contributing to susceptibility to MIS among ESRD patients.