From chronic kidney disease to transplantation: the roles of obestatin

Unacylated ghrelin and obestatin: promising biomarkers of protein energy wasting in children with chronic kidney disease

BACKGROUND

Impairment in orexigenic/anorexigenic hormone balance may be key in the pathogenesis of protein energy wasting in children with chronic kidney disease (CKD). Measurement of ghrelin and obestatin concentrations in children with CKD would help assess the potential contribution of these hormones to uremic protein energy wasting.

METHODS

This was a cross-sectional case-control study. Acylated and unacylated ghrelin and obestatin were measured in 42 children on conservative treatment (CT), 20 children on hemodialysis, 48 pediatric renal transplant (RTx) recipients and 43 controls (CTR) (mean age 11.9, range 5-20 years). Weight, height and bicipital, tricipital, subscapular and suprailiac folds were measured, and the body mass index-standard deviation score (BMI-SDS), percentage of fat mass and fat-free mass were calculated. Urea and creatinine were measured and the glomerular filtration rate (GFR) calculated.

RESULTS

Unacylated ghrelin level was higher in patients than controls (p = 0.0001), with the highest levels found in hemodialysis patients (p = 0.001 vs. CKD-CT, p = 0.0001 vs. RTx, p < 0.0001 vs. CTR). Obestatin level was significantly higher in patients on hemodialysis than those on conservative treatment, RTx recipients and controls (p < 0.0001 in each case). Unacylated ghrelin negatively correlated with weight-SDS (p < 0.0001), BMI-SDS (p = 0.0005) and percentage fat mass (p = 0.004) and positively correlated with percentage fat-free mass (p = 0.004). Obestatin concentration negatively correlated with weight-SDS (p = 0.007). Unacylated ghrelin and obestatin concentrations positively correlated with creatinine and urea and inversely with eGFR, even after adjustments for gender, age, puberty and BMI-SDS (p < 0.0001 for each model).

CONCLUSIONS

Unacylated ghrelin and obestatin, negatively related to renal function, seem to be promising inverse indicators of nutritional status in children with CKD. Potential therapeutic implications in terms of optimization of their removal in patients on hemodialysis could be hypothesized.

Emerging markers of cachexia predict survival in cancer patients

BACKGROUND

Cachexia may occur in 40% of cancer patients, representing the major cause of death in more than 20% of them. The aim of this study was to investigate the role of leptin, ghrelin and obestatin as diagnostic and predictive markers of cachexia in oncologic patients. Their impact on patient survival was also evaluated.

METHODS

140 adults with different cancer diagnoses were recruited. Thirty healthy volunteers served as control. Serum ghrelin, obestatin and leptin were tested at baseline and after a follow-up period of 18 months.

RESULTS

Ghrelin levels were significantly higher in cancer patients than in healthy subjects (573.31 ± 130 vs 320.20 ± 66.48 ng/ml, p < 0.0001), while obestatin (17.42 ± 7.12 vs 24.89 ± 5.54 ng/ml, p < 0.0001) and leptin (38.4 ± 21.2 vs 76.28 ± 17.48 ng/ml, p < 0.0001) values were lower. At ROC analyses the diagnostic profile of ghrelin (AUC 0.962; sensitivity 83%; specificity 98%), obestatin (AUC 0.798; sensitivity 74.5%; specificity 81.5%) and leptin (AUC 0.828; sensitivity 79%; specificity 73%) was superior to that of albumin (AUC 0.547; sensitivity 63%, specificity 69.4%) for detecting cachexia among cancer patients. On Cox multivariate analyses ghrelin (HR 1.02; 95% CI 1.01 - 1.03; p < 0.0001) and leptin (HR 0.94; 95% CI 0.92 - 0.96; p < 0.0001) were significant predictors of death even after correction for other known risk factors such as presence of metastasis and chronic kidney disease.

CONCLUSION

Ghrelin and leptin are promising biomarkers to diagnose cachexia and to predict survival in cancer patients.

Changes in ghrelin and obestatin levels before and after a meal in children with simple obesity and anorexia

BACKGROUND

Obestatin and ghrelin both have effects on the hypothalamus which controls food intake. We hypothesize that the circulating levels of obestatin and ghrelin may change after a meal and might be different between obesity and anorexia, which might be relevant to anorexia or obesity.

METHOD

Fifteen children with obesity, 25 children with anorexia and 17 normal-weight healthy controls were enrolled in the study. The preprandial and postprandial glucose, insulin, total ghrelin and obestatin tests were completed in the three groups. The values of these indices were compared.

RESULTS

The obesity group had the highest values for BMI and fasting glucose (p < 0.001), while the anorexia group had the highest values for obestatin and ghrelin, followed by the control and obesity groups. No differences in ratios of ghrelin to obestatin were found between the anorexia and obesity groups (p > 0.05), but both were higher than that of the control group (p < 0.05). BMI was negatively correlated with preprandial obestatin (r = -0.8413, p < 0.001) and ghrelin (r = -0.7400, p < 0.001), but showed no significant correlations with the ghrelin-to-obestatin ratio.

CONCLUSION

Although there is still controversy between the present and previous studies, the present study show that levels of obestatin and ghrelin are inversely correlated with BMI.