Abstract 424: Hyper-Inflammatory Macrophages in Coronary Artery Disease and Rheumatoid Arthritis; A Signature of CCL18, Krüppel-like Factor 2 and 4 and Oxidative Stress Response Genes

Abstract

Background: Autoimmune disease is an independent risk factor for accelerated coronary artery disease (CAD). Patients with rheumatoid arthritis (RA) have a 2-fold increased risk for CAD, comparable to the impact of diabetes mellitus. Abnormalities in the immune system contribute to both RA and CAD pathogenesis and defining these might elucidate disease mechanisms. We studied inflammatory macrophages in RA and CAD to identify shared and disease-specific molecular pathways. Methods: Patients with CAD and a history of myocardial infarction, patients with RA who satisfied the 2010 RA Classification Criteria and age-matched controls were enrolled. Monocytes isolated from peripheral blood were differentiated into macrophages and further polarized into M1 or M2 with IFNγ and lipopolysaccharide or IL-4 and IL-13, respectively. The expression of 55 genes was measured by quantitative PCR. Intracellular reactive oxygen species (ROS) were quantified using CellROX and the oxidant superoxide was scavenged using the SOD mimetic Tempol. Results: Both CAD and RA macrophages exhibited a gene expression signature of excess inflammatory activity when compared to controls. Besides the upregulation of cytokine genes, the hyper-inflammatory signature included the loss of the inflammatory suppressors Krüppel-like factor (KLF)-2 and KLF-4, and the gain of the chemokine CCL18 and the oxidative stress response gene, NAD(P)H:quinone oxidoreductase 1 (NQO1). Quantification of intracellular ROS confirmed increased oxidative stress in the patient-derived macrophages. To examine whether superoxide affects production of CCL18, cells were treated with Tempol. ROS depletion normalized the excess production of CCL18. Conclusion: Pro-inflammatory macrophages in RA and CAD share molecular abnormalities characterized by excessive cytokines and chemokine production, the loss of negative regulators and the gain of oxidative stress responses. Unbalanced ROS production is upstream of abnormal chemokine production and correcting redox balance in macrophages may be helpful in suppressing the hyper-inflammatory phenotype of these cells in CAD and in the CAD-prone autoimmune disease RA.