Abstract 4140558: Circulating plasma proteins in the Fontan circulation predict mitochondrial oxidative stress

Background: Single ventricle congenital heart disease such as hypoplastic left heart syndrome (HLHS) with a Fontan circulation constitute the largest group of children hospitalized with circulation failure, experiencing an in-hospital mortality rate of 20-50%. We investigated the mechanisms leading to circulation failure so as to identify novel therapeutic targets. Methods: Blood was collected from patients with HLHS s/p Fontan and controls with normal cardiac anatomy and function (N=6/group). Plasma microvesicles (MV) were isolated, and proteomics assessed using data independent acquisition mass spectroscopy. Dysregulated proteins with a fold change >1.5 or < -1.5, p<0.05, were evaluated using DAVID and Ingenuity pathway analysis. We assessed the association of most highly dysregulated proteins with NYHA class (clinical indicator of heart failure), right ventricular fractional area change (RV FAC) (echocardiographic indicator of RV systolic function), oxygen saturation and hemoglobin using Pearson correlation. Results: Age of Fontan patients vs. controls was 16.14±23 vs. 15.78±2; 40% were male in both groups. 80% of Fontan patients were in NYHA class II/III, 20% in NYHA class IV; 60% had Fontan-associated liver disease. Increasing expression of the following proteins was associated with worsening NYHA class: complement system (C1QA, r=0.91; C7, r=0.53; FCN3, r=0.52), membrane transporters (SLC2A1, r=0.82; SLC4A1, r=0.76), mitochondrial reactive oxygen species (mROS) generation (HSPD1, r=0.81; ATP5F1A, r=0.75) and cytoskeletal proteins (ANK1, r=0.63; ACTN1, r=0.76). Increasing expression of proteins involved in mROS generation were also associated with worsening RV FAC. Decreasing expression of the following proteins was associated with worsening NYHA class and RV FAC: B-cell lymphopoiesis (DOCK10; r=-0.80), adhesion (ADAM10, r=-0.72; CD151, r=-0.69), and coagulation (SERPINF2, r=-0.55). Higher expression of proteins involved in mitochondrial ROS generation and lower expression of proteins involved in lymphopoiesis and adhesion were associated with lower oxygen saturation and higher hemoglobin(Figure). Conclusion: Circulating plasma proteins in the Fontan circulation predict complement activation, mROS, cytoskeletal changes and decreased cell-cell adhesion. This circulating proteomic profile is associated with worsening heart failure and cyanosis providing mechanistic insight into heart failure progression and highlights novel therapeutic targets.