High-mobility group box 1 accelerates lipopolysaccharide-induced lung fibroblast proliferation in vitro: involvement of the NF-κB signaling pathway.

Abstract

The mechanism underlying lipopolysaccharide (LPS)-induced aberrant proliferation of lung fibroblasts in Gram-negative bacilli-associated pulmonary fibrosis is unknown. High-mobility group box 1 (HMGB1) is a ubiquitous nuclear protein that is released from the nuclei of lung fibroblasts after LPS stimulation. It can exasperate LPS-induced inflammation and hasten cell proliferation. Thus, this study investigated the effects of LPS- and/or HMGB1-stimulating murine lung fibroblasts on gene expression using various assays in vitro. Thiazolyl-diphenyl-tetrazolium bromide (MTT) assay data showed that either LPS or HMGB1 could induce lung fibroblast proliferation. Endogenous HMGB1 secreted from lung fibroblasts was detected by enzyme-linked immunosorbent assay (ELISA) 48 h after LPS stimulation. Pretreatment with an anti-HMGB1 antibody inhibited the proliferative effects of LPS on lung fibroblasts. DNA microarray data showed that the NF-κB signaling genes were upregulated in cells after stimulated with LPS, HMGB1, or both. Secretion of matrix metalloproteinase (MMP)-2 and MMP-9, and tissue inhibitor of metalloproteinase 2 (TIMP-2) was significantly upregulated after treatment with LPS, HMGB1, or their combination. However, an NF-κB inhibitor was able to downregulate levels of these proteins. In addition, levels of Toll-like receptor 4 (TLR4), Toll-like receptor 2 (TLR2), and receptors for advanced glycation end products (RAGE) mRNA and proteins were also upregulated in these cells after LPS treatment and further upregulated by LPS plus HMGB1. In conclusion, the data from the current study demonstrate that LPS-induced lung fibroblast secretion of endogenous HMGB1 can augment the proproliferative effects of LPS and, therefore, may play a key role in exacerbation of pulmonary fibrosis. The underlying molecular mechanisms are related to the activation of the TLR4/NF-κB signaling pathway and its downstream targets.

• Authors: Wen Li, Qiaoyi Xu, Yuxiao Deng, Zhongwei Yang, Shunpeng Xing, Xianyuan Zhao, Ping Zhu, Xiangrui Wang, Zhengyu He, Yuan Gao
• Journal: Laboratory investigation; a journal of technical methods and pathology (Lab Invest) Vol. 95 Issue 6 Pg. 635-47 (Jun 2015) ISSN: 1530-0307 [Electronic] United States
• PMID: 25867768 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• HMGB1 Protein
• Lipopolysaccharides
• NF-kappa B

Topics

• Animals
• Cell Line
• Cell Proliferation (drug effects)
• Fibroblasts (cytology, metabolism)
• HMGB1 Protein (pharmacology)
• Lipopolysaccharides (pharmacology)
• Lung (cytology)
• Mice
• NF-kappa B (metabolism)
• Pulmonary Fibrosis
• Signal Transduction (drug effects)