Abstract 16534: Remodeling of Intimal Matrix by C. Pneumoniae-infected Macrophages
Introduction: Chlamydia pneumoniae, an intracellular pulmonary pathogen, is considered an important risk factor for atherosclerosis through the mechanisms is poorly understood. Infected monocytes from the lung enter atherosclerotic foci, and create a pro-inflammatory environment in the intima. Here, we tested the hypothesis that C. pneumoniae infection contributes to intimal matrix remodeling using a 3D model.
Methods: Primary human monocytes infected with C. pneumoniae (either live of heat-killed organisms) at an MOI-1 were embedded in type I collagen matrix. Between 1 to 9 days, we analyzed the kinetics of MMP and cytokine release, cell migration, and structural and mechanical characteristics of the matrix by ELISA, microscopy and rheometry, respectively – with or without specific inhibitors of molecular mechanisms. All experiments were performed with at least 3 donors in triplicates; and statistical significance was assessed by Student’s t-test or ANOVA.
Results: We observed that the infection of macrophages encapsulated in a 3D collagen matrix promote: (i) the production of MMP and pro-inflammatory cytokines; (ii) the remodeling process including degradation, aggregation and realignment of fibers (Fig. A); (iii) an increase in macrophage podosomal extensions and microenvironmental interactions; (iv) the collective, coordinated migration of macrophages to form focal clusters (Fig. B); and (v) an increase in the elastic modulus (Fig. C). We observed that these changes were more pronounced in live than in heat-killed infection. Further, inhibition of MMP, chemotactic stimuli and cell migratory signaling attenuates matrix remodeling.
Significance: Our results provide novel insights into the role of infection and the mechanisms in modulating atherosclerotic progression, which may provide an attractive new approach to not only test the infectious burden hypothesis but also for the prevention and/or treatment of cardiovascular diseases.
Author Disclosures: S.J. Evani: None. S. Dallo: None. A.K. Ramasubramanian: None.
- © 2015 by American Heart Association, Inc.