Circulating Hsp90 Isoform Levels in Overweight and Obese Children and the Relation to Nonalcoholic Fatty Liver Disease: Results from a Cross-Sectional Study

Background. Obesity prevalence is increasing in children. It is associated with various comorbidities including nonalcoholic fatty liver disease (NAFLD). Hsp90 isoforms were identified in previous proteomic studies as potential biomarkers for NAFLD. The aim of the study was to analyze circulating levels of Hsp90 alpha and Hsp90 beta in overweight and obese children. In addition, Hsp90 alpha and Hsp90 beta were evaluated as biomarkers for NAFLD in overweight and obese children. Methods. 68 overweight and obese children and ten age- and gender-matched controls were recruited. Hsp90 alpha and Hsp90 beta levels were analyzed from serum in both controls and overweight and obese children by ELISA. Results. Serum Hsp90 beta and total Hsp90 levels were statistically significantly higher in overweight and obese children compared to controls. On the contrary, there was no difference in Hsp90 alpha levels between overweight and obese children and healthy controls. Hsp90 isoforms had different expression in NAFLD patients. Hsp90 beta levels were higher in overweight and obese NAFLD patients while Hsp90 alpha levels were lower. Hsp90 alpha to Hsp90 beta ratio had better accuracy for NAFLD diagnosis in obese and overweight patients compared to individual biomarkers. Conclusion. Hsp90 isoforms were confirmed on an independent cohort as biomarkers for NAFLD in overweight and obese children. In these patients, it seems to be more useful to separately analyze Hsp90 isoforms rather than total Hsp90 as the isoforms have greater discriminative capacity.