Serum Proteomic Analysis of Peripartum Cardiomyopathy Reveals Distinctive Dysregulation of Inflammatory and Cholesterol Metabolism Pathways

Background: The pathophysiology of peripartum cardiomyopathy (PPCM) and its distinctive biological features remain incompletely understood. High-throughput serum proteomic profiling, a powerful tool to gain insights into the pathophysiology of diseases at a systems biology level, has never been used to investigate PPCM relative to nonischemic cardiomyopathy. Objectives: The aim of this study was to characterize the pathophysiology of PPCM through serum proteomic analysis. Methods: Aptamer-based proteomic analysis (SomaScan 7K) was performed on serum samples from women with PPCM (n = 67), women with nonischemic nonperipartum cardiomyopathy (NPCM) (n = 31), and age-matched healthy peripartum and nonperipartum women (n = 10 each). Serum samples were obtained from the IPAC (Investigation of Pregnancy-Associated Cardiomyopathy) and IMAC2 (Intervention in Myocarditis and Acute Cardiomyopathy) studies. Results: Principal component analysis revealed unique clustering of each patient group (P for difference <0.001). Biological pathway analyses of differentially measured proteins in PPCM relative to NPCM, before and after normalization to pertinent healthy controls, highlighted specific dysregulation of inflammatory pathways in PPCM, including the upregulation of the cholesterol metabolism-related anti-inflammatory pathway liver-X receptor/retinoid-X receptor (LXR/RXR) (P < 0.01, Z-score 1.9-2.1). Cardiac recovery by 12 months in PPCM was associated with the downregulation of pro-inflammatory pathways and the upregulation of LXR/RXR, and an additional RXR-dependent pathway involved in the regulation of inflammation and metabolism, peroxisome proliferator-activated receptor α/RXRα signaling. Conclusions: Serum proteomic profiling of PPCM relative to NPCM and healthy controls indicated that PPCM is a distinct disease entity characterized by the unique dysregulation of inflammation-related pathways and cholesterol metabolism-related anti-inflammatory pathways. These findings provide insight into the pathophysiology of PPCM and point to novel potential therapeutic targets.