Open Access Research article

Characterization of monocyte/macrophage subsets in the skin and peripheral blood derived from patients with systemic sclerosis

Nobuyo Higashi-Kuwata1, Masatoshi Jinnin1*, Takamitsu Makino1, Satoshi Fukushima1, Yuji Inoue1, Faith C Muchemwa1, Yuji Yonemura2, Yoshihiro Komohara3, Motohiro Takeya3, Hiroaki Mitsuya45 and Hironobu Ihn1

Author Affiliations

1 Department of Dermatology & Plastic and Reconstructive Surgery, Faculty of Life Sciences, Kumamoto University, 1-1-1 Honjo, Kumamoto 860-8556, Japan

2 Department of Blood Transfusion Medicine and Cell Therapy, Faculty of Life Sciences, Kumamoto University, 1-1-1 Honjo, Kumamoto 860-8556, Japan

3 Department of Cell Pathology, Faculty of Life Sciences, Kumamoto University, 1-1-1 Honjo, Kumamoto 860-8556, Japan

4 Department of Hematology and Infectious Diseases, Faculty of Life Sciences, Kumamoto University, 1-1-1 Honjo, Kumamoto 860-8556, Japan

5 The experimental Retrovirology Section, HIV and AIDS Malignancy Branch, National Cancer Institute, 9000 Rockville Pike, Bethesda, MD, 20892, USA

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Arthritis Research & Therapy 2010, 12:R128  doi:10.1186/ar3066


See related editorial by Christmann and Lafyatis, http://arthritis-research.com/content/12/5/146

Published: 5 July 2010

Abstract

Introduction

Recent accumulating evidence indicates a crucial involvement of macrophage lineage in the pathogenesis of systemic sclerosis (SSc). To analyze the assembly of the monocyte/macrophage population, we evaluated the expression of CD163 and CD204 and various activated macrophage markers, in the inflammatory cells of the skin and in the peripheral blood mononuclear cells (PBMCs) derived from patients with SSc.

Methods

Skin biopsy specimens from 6 healthy controls and 10 SSc patients (7 limited cutaneous SSc and 3 diffuse cutaneous SSc) were analyzed by immunohistochemistry using monoclonal antibody against CD68 (pan-macrophage marker), CD163 and CD204. Surface and/or intracellular protein expression of CD14 (marker for monocyte lineage), CD163 and CD204 was analysed by flow cytometry in PBMCs from 16 healthy controls and 41 SSc patients (26 limited cutaneous SSc and 15 diffuse cutaneous SSc). Statistical analysis was carried out using Mann-Whitney U test for comparison of means.

Results

In the skin from SSc patients, the number of CD163+ cells or CD204+ cells between the collagen fibers was significantly larger than that in healthy controls. Flow cytometry showed that the population of CD14+ cells was significantly greater in PBMCs from SSc patients than that in healthy controls. Further analysis of CD14+ cells in SSc patients revealed higher expression of CD163 and the presence of two unique peaks in the CD204 histogram. Additionally, we found that the CD163+ cells belong to CD14brightCD204+ population.

Conclusions

This is the first report indicating CD163+ or CD204+ activated macrophages may be one of the potential fibrogenic regulators in the SSc skin. Furthermore, this study suggests a portion of PBMCs in SSc patients abnormally differentiates into CD14brightCD163+CD204+ subset. The subset specific to SSc may play an important role in the pathogenesis of this disease, as the source of CD163+ or CD204+ macrophages in the skin.