Identification and confirmation of haptoglobin as a potential serum biomarker in hypertrophic cardiomyopathy using proteomic approaches.

INTRODUCTION

Aiming at identifying biomarkers for hypertrophic cardiomyopathy (HCM), the serum proteome was explored through a two-dimensional gel-based proteomic approach (2D-DIGE) coupled with mass spectrometry and database interrogation.

METHODS

Serum samples from 20 male HCM patients and their sex- and age-matched controls were cleaned from interfering components. Patients and controls were pooled in five matched groups with the same age, and proteins extracts from each pool were labelled with cyanine dyes. Then, gel images were analysed using a fluorescence scanner and proteins were identified. Tryptic peptides were analysed by capillary reversed-phase liquid chromatography coupled online with tandem mass spectrometry (MS/MS).

RESULTS

Four different proteins were observed to be differentially expressed between HCM patients and their matched controls. Of them, decreases in haptoglobin levels were confirmed to be associated with HCM in an independent set of 181 consecutive HCM patients from our monographic clinic and 114 controls with similar age and sex using a nephelometer-based technique. Moreover, a significant negative correlation was observed between haptoglobin and subaortic gradient, thus highlighting the role of haptoglobin in HCM.

CONCLUSION

All these observations point out the utility of the 2D-DIGE proteomic strategy for the identification of serum proteins indicative of the presence of cardiac injury.