Retinol-binding protein 4: a promising circulating marker of liver damage in pediatric nonalcoholic fatty liver disease

Retinol binding protein 4 is associated with adiposity-related co-morbidity risk factors in children

OBJECTIVE

In adults, elevated levels of retinol binding protein 4 (RBP4) have been associated with biochemical markers of adiposity-related co-morbidities including insulin resistance, dyslipidemia, hypertension, and abdominal obesity. This study examined the relationship between RBP4 and risk factors for co-morbidities of adiposity in a population of ethnically diverse children in early- to mid-adolescence in the public school system of New York City.

MATERIALS/METHODS

We analyzed anthropometric (body mass index, % body fat, waist circumference), metabolic (lipids, glucose), and inflammatory (TNF-alpha, interleukin-6, C-reactive protein, adiponectin) markers for adiposity-related co-morbidities and serum alanine aminotransferase (ALT) in 106 school children (65 males, 41 females) 11-15 years of age (mean +/- SD = 13.0 +/- 0.1 years) who were enrolled in the Reduce Obesity and Diabetes (ROAD) project. Insulin sensitivity was assessed by quantitative insulin sensitivity check index. Insulin secretory capacity was measured as acute insulin response and glucose disposal index.

RESULTS

Serum RBP4 was significantly correlated directly with ALT, triglycerides, and triglyceride z-score, and inversely correlated with adiponectin. Correlations with ALT and adiponectin remained significant when corrected for % body fat, age, and gender. There were significant ethnic differences in the relationship of RBP4 to ALT, glucose disposal index and adiponectin.

CONCLUSIONS

In early- to mid-adolescents, circulating concentrations of RBP4 are correlated with multiple risk factors for adiposity-related co-morbidities. The observation that many associations persisted when corrected for % body fat, suggests that RBP4 can be viewed as an independent marker of adiposity-related co-morbidity risk in children.

Comparative analysis of serum proteomes of moyamoya disease and normal controls

OBJECTIVE

The etiology and pathogenesis of moyamoya disease remain unclear. Furthermore, the definitive diagnostic protein-biomarkers for moyamoya disease are still unknown. The present study analyzed serum proteomes from normal controls and moyamoya patients to identify novel serological biomarkers for diagnosing moyamoya disease.

METHODS

We compared the two-dimensional electrophoresis patterns of sera from moyamoya disease patients and normal controls and identified the differentially-expressed spots by matrix-assisted laser desorption/ionization-time-of flight mass spectrometry and electrospray ionization quadruple time-of-flight mass spectrometry.

RESULTS

We found and analyzed 22 differently-expressed proteomes. Two proteins were up-regulated. Twenty proteins were down-regulated. Complement C1 inhibitor protein and apolipoprotein C-III showed predominantly changed expressions (complement C1 inhibitor protein averaged a 7.23-fold expression in moyamoya patients as compared to controls, while apolipoprotein C-III averaged a 0.066-fold expression).

CONCLUSION

Although our study had a small sample size, our proteomic data provide serologic clue proteins for understanding moyamoya disease.

Nonalcoholic fatty liver disease in children

PURPOSE OF REVIEW

The intent of this review is to provide a concise overview of all recent acquisitions in terms of therapies and early noninvasive diagnostic approaches for nonalcoholic fatty liver disease (NAFLD) in children.

RECENT FINDINGS

NAFLD is increasingly being diagnosed in children. If undiscovered and if certain risks are present (i.e. obesity), nonalcoholic steatohepatitis, the most severe form of NAFLD, may silently progress to cirrhosis, hepatocarcinoma and liver-related death in adulthood. Current therapies include approaches for reducing the incidence of risk factors (i.e. weight reduction), drugs targeting the major molecular mechanisms thought essential in the pathogenesis of the disease (insulin resistance and oxidative stress) or both, but other novel treatments are under investigation.

SUMMARY

Although weight reduction, achieved through a combination of diet and exercise, makes it possible to modify the natural course of simple steatosis, the addition of adequate drugs might also provide a therapeutic action on nonalcoholic steatohepatitis. Moreover, preventive strategies and the design and translation into clinical practice of indices that integrate noninvasive diagnostic tools and serum biomarkers might be a winning approach for improving management of paediatric NAFLD/nonalcoholic steatohepatitis in the coming years.

Serum proteomics and biomarker discovery across the spectrum of nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD), ranging from relatively benign simple steatosis to progressive nonalcoholic steatohepatitis (NASH) and fibrosis, is an increasingly common chronic liver disease. Liver biopsy is currently the only reliable tool for staging the subtypes of NAFLD; therefore, noninvasive serum biomarkers for evaluation of liver disease and fibrosis are urgently needed. We performed this study to describe changes in the serum proteome and identify biomarker candidates in serum samples from 69 patients with varying stages of NAFLD (simple steatosis, NASH, and NASH with advanced bridging [F3/F4] fibrosis) and 16 obese controls. Using a label-free mass spectrometry-based approach we identified over 1,700 serum proteins with a peptide identification (ID) confidence level of >75%, 605 of which changed significantly between any two patient groups (false discovery rate <5%). Importantly, expression levels of 55 and 15 proteins changed significantly between the simple steatosis and NASH F3/F4 group and the NASH and NASH F3/F4 group, respectively. Classification of proteins with significant changes showed involvement in immune system regulation and inflammation, coagulation, cellular and extracellular matrix structure and function, and roles as carrier proteins in the blood. Further, many of these proteins are synthesized exclusively by the liver and could potentially serve as diagnostic biomarkers for identifying and staging NAFLD.

CONCLUSION

This proteomic analysis reveals important information regarding the pathogenesis/progression of NAFLD and NASH and demonstrates key changes in serum protein expression levels between control subjects and patients with different stages of fatty liver. Future validation of these potential biomarkers is needed such that these proteins may be used in place of liver biopsy to facilitate diagnosis and treatment of patients with NAFLD.