An unrestrained proinflammatory M1 macrophage population induced by iron impairs wound healing in humans and mice

• Published in: The Journal of clinical investigation Vol. 121; no. 3; pp. 985 - 997
• Main Authors: Sindrilaru, Anca, Peters, Thorsten, Wieschalka, Stefan, Baican, Corina, Baican, Adrian, Peter, Henriette, Hainzl, Adelheid, Schatz, Susanne, Qi, Yu, Schlecht, Andrea, Weiss, Johannes M., Wlaschek, Meinhard, Sunderkötter, Cord, Scharffetter-Kochanek, Karin
• Format: Journal Article
• Language: English
• Published: United States American Society for Clinical Investigation 01.03.2011
• Subjects: Animals; Biomedical research; Cellular Senescence; Cyclin-Dependent Kinase Inhibitor p16 - metabolism; Cytokines; Fibroblasts; Fibroblasts - metabolism; Gene expression; Growth factors; Health aspects; Humans; Hydroxyl Radical - metabolism; Hypertension; Inflammation; Inflammatory diseases; Iron - metabolism; Iron in the body; Leg ulcers; Leukocytes; Macrophages; Macrophages - cytology; Macrophages - metabolism; Mice; Models, Biological; Neutrophils; Pathogenesis; Phenotype; Physiological aspects; Reactive Oxygen Species; Risk factors; Tumor Necrosis Factor-alpha - metabolism; Wound Healing; Germany; Romania
• ISSN: 0021-9738; 1558-8238; 1558-8238
• DOI: 10.1172/JCI44490

Uncontrolled macrophage activation is now considered to be a critical event in the pathogenesis of chronic inflammatory diseases such as atherosclerosis, multiple sclerosis, and chronic venous leg ulcers. However, it is still unclear which environmental cues induce persistent activation of macrophages in vivo and how macrophage-derived effector molecules maintain chronic inflammation and affect resident fibroblasts essential for tissue homeostasis and repair. We used a complementary approach studying human subjects with chronic venous leg ulcers, a model disease for macrophage-driven chronic inflammation, while establishing a mouse model closely reflecting its pathogenesis. Here, we have shown that iron overloading of macrophages--as was found to occur in human chronic venous leg ulcers and the mouse model--induced a macrophage population in situ with an unrestrained proinflammatory M1 activation state. Via enhanced TNF-α and hydroxyl radical release, this macrophage population perpetuated inflammation and induced a p16(INK4a)-dependent senescence program in resident fibroblasts, eventually leading to impaired wound healing. This study provides insight into the role of what we believe to be a previously undescribed iron-induced macrophage population in vivo. Targeting this population may hold promise for the development of novel therapies for chronic inflammatory diseases such as chronic venous leg ulcers.