A Cross-Species Proteomic Investigation of Atrial Fibrillation: Insights from Equine and Human Hearts

Background: Horses and humans are among the few mammals prone to developing spontaneous atrial fibrillation (AF), both suffering from high recurrence rates after treatment. Treatment resistance is often attributed to functional, structural, and metabolic remodeling of the atria. The aim of this explorative study was to evaluate the molecular pathways associated with early stages of AF in horses and to compare the AF proteomes between horses and humans. Methods: We performed data-independent acquisition mass spectrometry on myocardial biopsies collected from the right atrium (RA), left atrium (LA), and left ventricular chamber (LV) in horses with early stages of naturally occurring persistent AF and controls (n=8 in each group). Results: We identified a total of 3400 quantifiable proteins, several of which were differentially regulated between AF horses and controls (268 in RA, 324 in LA, and 284 in LV, p<0.05). Pathway enrichment analyses identified changes in metabolic, contractile, and extracellular matrix (ECM) proteins. Atrial hypocontractility and ECM remodeling were confirmed by echocardiography and histology, respectively. Key proteomic changes in horses with AF overlapped with human AF public datasets, underscoring the translational relevance of the equine AF model. Particularly, contractile proteins, such as cardiac troponins (TNNT2), myosin (MYH6) and tropomyosin (TPM2), along with metabolic regulators as heat shock protein family A (HSPA4) and Proteasome 26S Subunit, Non-ATPase 13 (PSMD13) were shared between horses and humans with AF. Moreover, a significant increase in several ECM glycoproteins was detected in both species, highlighting the importance of early ECM remodeling that extends beyond the fibrotic changes often associated with AF. Conclusion: The horse and human cardiac proteome share similar AF-related changes. Metabolic, functional, and structural protein changes identified in early-stage AF may provide clues to pharmacological targets for preventing AF-associated atrial remodeling and improving treatment success across species.

背景：马与人类是少数可自发罹患心房颤动（atrial fibrillation, AF）的哺乳动物，二者在接受治疗后均存在较高的复发率。治疗抵抗常被归因于心房的功能、结构与代谢重塑。本项探索性研究旨在评估马类早期心房颤动相关的分子通路，并对比马与人类的心房颤动蛋白质组（proteome）特征。方法：我们对罹患早期自发性持续性心房颤动的马类及对照组（每组各8例）采集的右心房（right atrium, RA）、左心房（left atrium, LA）与左心室腔（left ventricular chamber, LV）心肌活检样本，开展了数据非依赖采集质谱（data-independent acquisition mass spectrometry）分析。结果：本研究共鉴定出3400种可定量蛋白质，其中心房颤动马类与对照组间存在差异表达的蛋白质共268种（右心房）、324种（左心房）及284种（左心室腔），差异均具有统计学意义（p<0.05）。通路富集分析显示，代谢、收缩及细胞外基质（extracellular matrix, ECM）相关蛋白质存在表达变化。超声心动图与组织病理学检测分别验证了心房收缩功能减退与细胞外基质重塑现象。心房颤动马类的核心蛋白质组变化与人类心房颤动公共数据集存在重叠，凸显了马类心房颤动模型的转化研究价值。具体而言，收缩相关蛋白质（如心肌肌钙蛋白TNNT2、肌球蛋白MYH6与原肌球蛋白TPM2），以及代谢调节因子如热休克蛋白家族A（HSPA4）与26S蛋白酶体非ATP酶亚基13（PSMD13），在心房颤动马类与人类中均存在共通的表达改变。此外，两类物种中均检测到多种细胞外基质糖蛋白的显著上调，这凸显了早期细胞外基质重塑的重要性——该过程远超心房颤动常伴随的纤维化改变范畴。结论：马类与人类的心脏蛋白质组存在相似的心房颤动相关表达变化。早期心房颤动中鉴定出的代谢、功能及结构蛋白质变化，可为跨物种预防心房颤动相关心房重塑、提升治疗成功率的药理学靶点开发提供思路。