Ly6C(low) and not Ly6C(high) macrophages accumulate first in the heart in a model of murine pressure-overload

PLoS One. 2014 Nov 21;9(11):e112710. doi: 10.1371/journal.pone.0112710. eCollection 2014.

Abstract

Cardiac tissue remodeling in the course of chronic left ventricular hypertrophy requires phagocytes which degrade cellular debris, initiate and maintain tissue inflammation and reorganization. The dynamics of phagocytes in left ventricular hypertrophy have not been systematically studied. Here, we characterized the temporal accumulation of leukocytes in the cardiac immune response by flow cytometry and fluorescence microscopy at day 3, 6 and 21 following transverse aortic constriction (TAC). Cardiac hypertrophy due to chronic pressure overload causes cardiac immune response and inflammation represented by an increase of immune cells at all three time points among which neutrophils reached their maximum at day 3 and macrophages at day 6. The cardiac macrophage population consisted of both Ly6C(low) and Ly6C(high) macrophages. Ly6C(low) macrophages were more abundant peaking at day 6 in response to pressure overload. During the development of cardiac hypertrophy the expression pattern of adhesion molecules was investigated by qRT-PCR and flow cytometry. CD11b, CX3CR1 and ICAM-1 determined by qRT-PCR in whole cardiac tissue were up-regulated in response to pressure overload at day 3 and 6. CD11b and CX3CR1 were significantly increased by TAC on the surface of Ly6C(low) but not on Ly6C(high) macrophages. Furthermore, ICAM-1 was up-regulated on cardiac endothelial cells. In fluorescence microscopy Ly6C(low) macrophages could be observed attached to the intra- and extra-vascular vessel-wall. Taken together, TAC induced the expression of adhesion molecules, which may explain the accumulation of Ly6C(low) macrophages in the cardiac tissue, where these cells might contribute to cardiac inflammation and remodeling in response to pressure overload.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cardiomegaly / immunology*
  • Cardiomegaly / physiopathology
  • Disease Models, Animal
  • Female
  • Flow Cytometry
  • Macrophages / immunology*
  • Mice
  • Mice, Inbred C57BL
  • Microscopy, Fluorescence
  • Pressure
  • Real-Time Polymerase Chain Reaction

Grants and funding

The authors acknowledge support by the flow-cytometry core facility and by the House for Experimental Therapy (HET) of the medical faculty of Bonn University. CW was supported by the Else Kröner-Forschungskolleg Bonn, and CK is a member of the excellence cluster “ImmunoSensation” at Bonn University. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.