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.

Retracted: Circular RNA ANKRD36 attends to lipopolysaccharide‐aroused MRC‐5 cell injury via regulating microRNA‐31‐3p

“…Lots of literatures reported that NF‐κB pathway was activated in pneumonia . Earlier research also confirmed that LPS could activate NF‐κB pathway in lung fibroblast cells . Shi et al indicated that silencing circANKRD36 could inhibit NF‐κB pathway in myocardial H9c2 cells .…”

HMGB1 induces lung fibroblast to myofibroblast differentiation through NF-κB-mediated TGF-β1 release

“…It has been reported that HMGB1 accelerates lipopolysaccharide-induced lung fibroblast proliferation in vitro via the NF-κB signaling pathway (38). Conversely, the present study demonstrated that NF-κB activation in lung fibroblasts, induced by HMGB1, may promote TGF-β1 release and induce fibroblast to myofibroblast differentiation.…”

Activation of AMP‐activated protein kinase during sepsis/inflammation improves survival by preserving cellular metabolic fitness

“…We elected to use a combined insult because this model (a) Associates the effect of DAMPs and PAMPs on a mono‐cellular culture, better resembling the septic milieu to which TEC may be exposed; (b) Combines prototypical molecules that induce early (LPS) and late (HMGB1) inflammatory injury during sepsis; (c) Was shown by Li et al, to increase mRNA and protein expression of TLR2 and 4 receptors more than LPS or HMGB1 alone, which is known to be part of the innate renal response to sepsis; and (d) proved to increase MCP‐1 more than LPS alone (Figure S1), without inducing more cell death in our preliminary studies. Inflammatory mix was composed of the following concentrations based on our preliminary data (Figure S1) and work by Li et al 28 : lipopolysaccharide ( Escherichia coli , Sigma, L2630 in HBSS media, Gibco 14025‐076, 10 μg/mL) plus High mobility group box 1 (HMGB1) (1 μg/mL). We selected the concentrations of AICAR and Compound C based on preliminary pilot studies showing adequate AMPK activation and inhibition (data not shown).…”