Differences in atrial fibrillation-associated proteins between the left and right atrial appendages from patients with rheumatic mitral valve disease: A comparative proteomic analysis

The majority of proteomic studies have focused on identifying atrial fibrillation (AF)-associated proteins in the right atrium (RA), thus potential differences in AF‑associated proteins between the RA and left atrium (LA) remain unknown. The aim of the present study was to perform proteomic analysis to compare the potential differences in AF‑associated proteins between the right atrial appendage (RAA) and left atrial appendage (LAA) in patients with rheumatic mitral valve disease (RMVD). RAA and LAA tissues were obtained from 18 patients with RMVD (10 with AF) during mitral valve replacement surgery. Two‑dimensional fluorescence difference gel electrophoresis (2‑D DIGE) proteomics analysis was performed using these tissues to identify AF‑associated proteins in RAA and LAA. Subsequently, the proteomics data was validated using western blot analysis of nine selected proteins. In RAA, 32 AF‑associated proteins were significantly dysregulated (15 upregulated and 17 downregulated). In LAA, 31 AF‑associated proteins were significantly dysregulated (13 upregulated and 18 downregulated). Among these AF‑associated proteins, 17 were AF‑associated in both RAA and LAA, 15 were AF‑associated only in RAA, and 14 were AF‑associated only in LAA. Amongst the differentially expressed proteins, western blot analysis validated the results for 6 AF‑associated proteins, and demonstrated similar distributions in RAA and LAA compared with the 2‑D DIGE results. Of these proteins, 2 proteins were AF‑associated in both RAA and LAA, 2 were AF‑associated only in RAA, and 2 were AF‑associated only in LAA. Additionally, the different distributions of AF‑associated proteins in the RAA and LAA of patients with RMVD was analyzed, which may reflect the different regulatory mechanisms of the RA and LA in AF. These findings may provide new insights into the underlying molecular mechanisms of AF in patients with RMVD.