Comprehensive Proteomics Profiling Reveals Circulating Biomarkers of Hypertrophic Cardiomyopathy

Abstract

Background: Hypertrophic cardiomyopathy (HCM) is caused by mutations in the genes coding for proteins essential in normal myocardial contraction. However, it remains unclear through which molecular pathways gene mutations mediate the development of HCM. The objectives were to determine plasma protein biomarkers of HCM and to reveal molecular pathways differentially regulated in HCM.

Methods: We conducted a multicenter case-control study of cases with HCM and controls with hypertensive left ventricular hypertrophy. We performed plasma proteomics profiling of 1681 proteins. We performed a sparse partial least squares discriminant analysis to develop a proteomics-based discrimination model with data from 1 institution (ie, the training set). We tested the discriminative ability in independent samples from the other institution (ie, the test set). As an exploratory analysis, we executed pathway analysis of significantly dysregulated proteins. Pathways with false discovery rate <0.05 were declared positive.

Results: The study included 266 cases and 167 controls (n=308 in the training set; n=125 in the test set). Using the proteomics-based model derived from the training set, the area under the receiver operating characteristic curve was 0.89 (95% CI, 0.83-0.94) in the test set. Pathway analysis revealed that the Ras-MAPK (mitogen-activated protein kinase) pathway, along with its upstream and downstream pathways, was upregulated in HCM. Pathways involved in inflammation and fibrosis-for example, the TGF (transforming growth factor)-β pathway-were also upregulated.

Conclusions: This study serves as the largest-scale investigation with the most comprehensive proteomics profiling in HCM, revealing circulating biomarkers and exhibiting both novel (eg, Ras-MAPK) and known (eg, TGF-β) pathways differentially regulated in HCM.

Keywords: biomarkers; cardiomyopathies; hypertrophy; mutation; proteomics.

Figure 1.. Three-dimensional score plot of proteomics profiling in cases with hypertrophic cardiomyopathy and controls with hypertensive left ventricular hypertrophy.

Each red dot represents the proteomic profile of an HCM case. Each green dot corresponds to that of a hypertensive LVH control. N = 433 (266 cases and 167 controls). HCM = hypertrophic cardiomyopathy, LVH = left ventricular hypertrophy

Figure 2.. Area under the receiver-operating-characteristic curve in the independent test set, using the proteomics-based discrimination model developed in the training set.

N = 308 (191 cases and 117 controls) in the training set; N = 125 (75 cases and 50 controls) in the test set. AUC = area under the receiver-operating-characteristic curve, CI = confidence interval

Figure 3.. The 30 most discriminant proteins to distinguish cases with hypertrophic cardiomyopathy from controls with hypertensive left ventricular hypertrophy.

A red box indicates that the protein concentration was increased in HCM, while a green box means that the concentration was decreased in HCM. P values were computed using the Mann-Whitney-Wilcoxon test. Fold change was calculated by dividing the median in the cases by the median in the controls. The discrimination model was developed using the training set with N = 308 (191 cases and 117 controls). HCM = hypertrophic cardiomyopathy