P6390Macrophages as contributors to chronic inflammation and cardiac fibrosis in patients with myocardial infarction
Authors: Gombozhapova A , Rogovskaya Y , Rebenkova M , Kzhyshkowska J , Ryabov V 
Published: October 2019

Abstract

Introduction
The functional characteristics of tissue macrophages associated with the progression of cardiac fibrosis in clinic are still unknown.

Purpose
The purpose was to study cardiac macrophage phenotypes contributing to the development of chronic inflammation and fibrosis in patients with myocardial infarction (MI).

Methods
The study included 41 patients with fatal MI type 1. Group 1 (n=24) comprised patients who died within 72 hours of MI (the inflammatory phase) and group 2 (n=17) comprised patients who died 4–28 days after MI (the regenerative phase). Macrophage infiltration (number of cells) in the heart was assessed by double immunofluorescence in the non-infarct area. Each area was evaluated in 20 random fields. We used CD163, CD206, stabilin-1, α-smooth muscle actin (α-SMA), interleukin-10 (IL-10) as markers of M2-like macrophages.

Results
The number of CD163+/CD206− (p=0.087) and CD163+/206+ (p=0.072) macrophages was higher during the regenerative phase of MI. The number of CD163-/CD206+, stabilin-1+/α-SMA-, stabilin-1+/α-SMA+, stabilin-1+/IL-10−, stabilin-1+/IL-10+, stabilin-1-/IL-10+ did not significantly change throughout the entire period of MI. The comparison of various M2 macrophage subpopulations into groups revealed following. In group 1 the number of CD163+/CD206− and CD163+/CD206+ cells prevailed over CD163−/CD206+ (p=0.033 and p=0.003, respectively), stabilin1+/α-SMA− cells over stabilin-1+/α-SMA+ (p<0.001), and stabilin-1+/IL-10+ cells over stabilin-1+/IL-10− (p=0.018). In group 2 the quantity of stabilin-1+/α-SMA− macrophages prevailed over stabilin-1+/α-SMA+ (p=0.005) and stabilin-1+/IL-10+ over stabilin-1−/IL-10+ (p=0.028). In group 1 the number of CD163+/CD206+ cells correlated with the absolute and the relative number of peripheral blood monocytes prior to the onset of death (R=0.97), while the quantity of stablin-1+/α-SMA+ cells correlated with the absolute number of peripheral blood monocytes at admission (R=-0.53). In group 2 the quantity of CD206+/CD163− cells correlated with the absolute and the relative number of monocytes in the peripheral blood at admission (R=0.73 and R=0.59, respectively), the quantity of CD163+/CD206− macrophages with the incidence of recurrent MI (R= 0.54), and the number of stabilin-1+/α-SMA+ macrophages with the age of patients (R=-0.58).

Conclusions
We have suggested that the key cardiac macrophage phenotypes contributing to the development of chronic inflammation and cardiac fibrosis in the regenerative phase of MI were stabilin-1+/α-SMA− and stabilin-1+/IL-10+. We revealed subpopulation of stabilin-1+/α-SMA+ macrophages, that indicated the possibility of cellular transdifferentiation and macrophage plasticity. Thus, our results supports that understanding the role of macrophages in initiation, progression, and resolution of cardiac fibrosis is one of the most promising goal in the design of anti-fibrotic treatment strategies for patients with MI.