HMGB‐1 induces c‐kit+ cell microvascular rolling and adhesion via both toll‐like receptor‐2 and toll‐like receptor‐4 of endothelial cells

• Published in: Journal of cellular and molecular medicine 2012-05, Vol.16 (5), p.1094-1105
• Main Authors: Furlani, Dario, Donndorf, Peter, Westien, Ingeborg, Ugurlucan, Murat, Pittermann, Erik, Wang, Weiwei, Li, Wenzhong, Vollmar, Brigitte, Steinhoff, Gustav, Kaminski, Alexander, Ma, Nan
• Format: Article
• Language: English
• Subjects: Animals; Blood; Bone marrow; c-Kit protein; Cell activation; Cell Adhesion - drug effects; Cell adhesion molecules; Cell migration; Cell Movement - drug effects; cremaster muscle; c‐kit; Endothelial cells; Endothelium; Gene expression; high‐mobility group box 1; HMGB1 protein; HMGB1 Protein - metabolism; HMGB1 Protein - pharmacology; Immunofluorescence; Inflammation; intravital microscopy; Laboratory animals; Leukocyte Rolling - drug effects; Leukocyte Rolling - physiology; Lipopolysaccharides; Male; Mice; Mice, Inbred C3H; Mice, Inbred C57BL; Mice, Knockout; Microscopy; Microvasculature; Microvessels - drug effects; Microvessels - physiology; mRNA; Muscle, Skeletal - drug effects; Nitric Oxide Synthase Type III - biosynthesis; Nitric-oxide synthase; Original; Proto-Oncogene Proteins c-kit - physiology; Stem cells; TLR2 protein; TLR4 protein; Toll-Like Receptor 2 - metabolism; Toll-Like Receptor 4 - metabolism; Toll-like receptors
• ISSN: 1582-1838; 1582-4934
• DOI: 10.1111/j.1582-4934.2011.01381.x

High‐mobility group box 1 (HMGB‐1) is a strong chemo‐attractive signal for both inflammatory and stem cells. The aim of this study is to evaluate the mechanisms regulating HMGB‐1–mediated adhesion and rolling of c‐kit+ cells and assess whether toll‐like receptor‐2 (TLR‐2) and toll‐like receptor‐4 (TLR‐4) of endothelial cells or c‐kit+ cells are implicated in the activation of downstream migration signals to peripheral c‐kit+ cells. Effects of HMGB‐1 on the c‐kit+ cells/endothelial interaction were evaluated by a cremaster muscle model in wild‐type (WT), TLR‐2 (−/−) and Tlr4 (LPS‐del) mice. The mRNA and protein expression levels of endothelial nitric oxide synthase were determined by quantitative real‐time PCR and immunofluorescence staining. Induction of crucial adhesion molecules for rolling and adhesion of stem cells and leukocytes were monitored in vivo and in vitro. Following local HMGB‐1 administration, a significant increase in cell rolling was detected (32.4 ± 7.1% in ‘WT’ versus 9.9 ± 3.2% in ‘control’, P < 0.05). The number of firmly adherent c‐kit+ cells was more than 13‐fold higher than that of the control group (14.6 ± 5.1 cells/mm2 in ‘WT’ versus 1.1 ± 1.0 cells/mm2 in ‘control’, P < 0.05). In knockout animals, the fraction of rolling cells did not differ significantly from control levels. Firm endothelial adhesion was significantly reduced in TLR‐2 (−/−) and Tlr4 (LPS‐del) mice compared to WT mice (1.5 ± 1.4 cells/mm2 in ‘TLR‐2 (−/−)’ and 2.4 ± 1.4 cells/mm2 in ‘Tlr4 (LPS‐del)’ versus 14.6 ± 5.1 cells/mm2 in ‘WT’, P < 0.05). TLR‐2 (−/−) and Tlr4 (LPS‐del) stem cells in WT mice did not show significant reduction in rolling and adhesion compared to WT cells. HMGB‐1 mediates c‐kit+ cell recruitment via endothelial TLR‐2 and TLR‐4.