Abstract P537: Reduced Cardiovascular Regenerative Capacity is Associated With Enhanced Inflammatory Response to Acute Psychological Stress

Abstract

Background: Bone marrow-derived progenitor cells (PCs) are involved in vascular regeneration and correlate with vascular function and cumulative cardiovascular risk. Systemic inflammation is associated with increased mobilization and differentiation of circulating PCs (CPCs) which may ultimately lead to exhaustion of vascular regenerative capacity. Individuals with coronary artery disease (CAD) exhibit a pro-inflammatory response to a mental stress challenge that has been associated with an elevated risk of adverse outcomes. We sought to determine whether subjects with reduced numbers of circulating PCs (CPCs) are at higher risk of a pro-inflammatory response to acute mental stress. Methods: 500 outpatients with stable CAD were enrolled into the Mental Stress Ischemia Prognosis study and underwent a laboratory-based mental stress protocol. Mononuclear cells expressing CD45med, CD34 and CXCR4 epitopes, known to be enriched for hematopoietic PCs, were enumerated using flow cytometry. Interleukin-6 (IL6) and C-Reactive Protein (CRP) levels were measured before and after mental stress. Baseline and changes in IL6 levels were compared across CPC tertiles using linear regression after adjusting for patient characteristics. Results: Mean age was 63± 9 years, 77% male, 70% white. Median CD34+ CPC count was 1.64 (1.02-2.43 cells/μL. CPC levels were not associated with either the baseline IL6 level (Beta= 0.071 95%CI, -0.091, 0.23) or CRP levels (Beta, 0.60, 95%CI, -0.25, 0.44). However, independent of demographics, CAD risk factors and baseline IL6 levels, lower CD34+/CXCR4+ CPC counts were associated with a higher inflammatory response during mental stress, measured as a rise in IL6 level (Beta= -0.11, 95%CI, -0.20, -0.028). Conclusions: Patients with reduced CPC levels have a greater pro-inflammatory response to mental stress. Thus, the observed higher risk in subjects with impaired regenerative capacity might be at least partly due to a higher stress-related pro-inflammatory response.