Insights into type 2 diabetes mellitus in atrial fibrillation patients: a proteomics approach
Authors: Atzemian N , Androutsopoulou V , Portokallidou K , Leonidis G , Pallikarou M , Ragia G , Karangelis D , Mikroulis D , Manolopoulos V G 
Published: October 2024

Abstract

Introduction
Atrial fibrillation (AF) and Type 2 Diabetes Mellitus (T2DM) are two closely interconnected conditions, sharing a complex relationship within cardiac pathophysiology. Common risk factors such as obesity, hypertension, inflammation, and endothelial dysfunction contribute to their coexistence. T2DM is known to drive cardiac fibrosis and promote electrical and structural remodeling of the heart, creating a substrate conducive to AF onset, while AF in T2DM patients increases the risk of adverse cardiovascular outcomes, such as stroke. Understanding this complex relationship is pivotal for improving the therapeutic and preventive strategies for these patients. This study aims to examine the proteomic differences between AF patients with and without T2DM, providing novel insights into pathophysiological mechanisms and identifying novel therapeutic targets and biomarkers.

Methods
In total, 14 AF patients undergoing open-heart surgery, comprising of 6 T2DM individuals and 8 non-T2DM individuals have been included. The mean age of the T2DM patients was 69.5 ± 10 years, while the non-T2DM was 69.3 ± 8.2 and BMI was 29.2 ± 2.9 and 29.5 ± 3 respectively. Right atrial appendages (RAA) from these patients were obtained in an RNA stabilization solution during open-heart surgery and processed using the phenol-based method for protein extraction. The proteins were digested with trypsin to generate peptides, followed by an additional clean-up step using C18 pipette tips. The prepared peptide samples were analyzed by employing a label-free-based quantitative (LFQ) approach, using a C18 (75cmx75cm) column. Proteomic analysis was performed using a Nano liquid chromatography system coupled to tandem mass spectrometer (nano LC-MS/MS), followed by a comprehensive bioinformatics analysis, using appropriate software.

Results
A total of 1548 proteins were identified, of which 899 could be quantified using LFQ analysis. Applying strict significance criteria, including FDR &lt;0.1 and Abundance ratio (AR)&gt;2 or &lt;0.5, we identified 100 differential expressed proteins, with 21 upregulated and 79 downregulated in T2DM (Fig.1). Most notably, DPP9 and ATP1A2 were overexpressed in hearts of AF patients with T2DM (AR=100), while INPPL1 and ARID5A were underexpressed (AR=0.01), thereby representing attractive therapeutic targets. In pathway enrichment analysis (Fig.2), the dysregulated proteins participate in noteworthy pathways, including Non-alcoholic fatty liver disease (NAFLD), Type II diabetes mellitus, and Insulin signaling pathway.

Conclusion
Given the increased morbidity associated with the coexistence of AF and T2DM, there is a pressing need for novel therapeutic strategies tailored to this patient population. While AF and T2DM share certain molecular characteristics in the heart, this study emphasizes the necessity for further evaluation and validation of the distinct proteomic signatures identified.Fig.1:Volcano PlotFig.2:Protein Enrichment Network