Human Gingival CD14⁺Fibroblasts Primed with Gamma Interferon Increase Production of Interleukin-8 in Response to Lipopolysaccharide through Up-Regulation of Membrane CD14 and MyD88 mRNA Expression

Abstract

Gamma interferon (IFN-γ)-primed human gingival fibroblasts (HGF) have been shown to produce higher levels of interleukin-8 (IL-8) upon stimulation with bacterial products and inflammatory cytokines than nonprimed controls. In this study, we examined whether priming of HGF with IFN-γ up-regulates IL-8 production by the cells in response to purified lipopolysaccharide (LPS). The priming effect of IFN-γ was clearly observed in the high-CD14-expressing (CD14high) HGF but not in the low-CD14-expressing (CD14low) HGF. The CD14high HGF were most effectively primed with IFN-γ (1,000 IU/ml) for 72 h. To elucidate the mechanism of the priming effects of IFN-γ for the LPS response by HGF, we examined whether IFN-γ regulated expression of CD14, Toll-like receptor 2 (TLR2), TLR4, MD-2, and MyD88, all of which are molecules suggested to be associated with LPS signaling. In CD14high HGF, IFN-γ markedly up-regulated CD14 and MyD88 but not TLR4 protein and MD-2 mRNA expression, while in CD14low HGF, IFN-γ slightly increased MyD88 and scarcely affected CD14, TLR4 protein, and MD-2 mRNA levels. LPS-induced IL-8 production by IFN-γ-primed CD14high HGF was significantly inhibited by monoclonal antibodies (MAbs) against CD14 and TLR4, but not by an anti-TLR2 MAb. These findings suggested that IFN-γ primed CD14high HGF to enhance production of IL-8 in response to LPS through augmentation of the CD14-TLR system, where the presence of membrane CD14 was indispensable for the response of HGF to LPS

Priming of human oral epithelial cells by interferon-γ to secrete cytokines in response to lipopolysaccharides, lipoteichoic acids and peptidoglycans

“…Alternatively, the priming activity of IFN-ª may be due to augmentation of the TLR-MyD88 signalling pathway, which mediates signalling not only of gram-negative but also of gram-positive bacterial cell-surface components, irrespective of CD14 [44][45][46]. In this context, this group confirmed that IFN-ª up-regulated mCD14 expression and MyD88 mRNA expression by human gingival fibroblasts, and resulted in enhanced production of IL-8 by the cells in response to Salmonella LPS [29]. Faure et al reported that IFN-ª induced TLR2 and TLR4 expression in human endothelial cells.…”

“…Previous studies [26][27][28] showed that human gamma-interferon (IFN-ª) primed human gingival fibroblasts (HGF) to enhance production of inflammatory cytokines upon stimulation with the LPS fraction from black-pigmented bacteria (BPB) such as Porphyromonas gingivalis and Prevotella intermedia. Furthermore, IFN-ª primed HGF which highly expressed membrane CD14 (mCD14) to increase expression of mCD14 and mRNA for CD14, TLR4 and MyD88, resulting in production of higher levels of IL-8 than non-primed cells upon stimulation with purified Salmonella LPS [29].…”

Endogenous IL-15 Sustains Recruitment of IL-2Rβ and Common γ and IL-2-Mediated Chemokine Production in Normal and Inflamed Human Gingival Fibroblasts

“…These observations also suggest that HGF in inflamed regions are actively involved in the inflammatory process by producing high concentrations of chemokines in response to exogenous IL-2/IL-15 as well as LPS. It has previously been shown that normal HGF primed with IFN-␥ produce increased levels of chemokines in response to LPS through up-regulation of CD14 and MyD88 mRNA expression (5). IFN-␥ treatment (1000 IU/ml for 3 days) induced the expression of IL-15R␣ mRNA, but had no effect on the expression of IL-2R␣ mRNA and surface expression of IL-15 (Ref.…”

“…Fibroblasts are not a homogeneous population in different anatomical regions or even within a single tissue, and are considered to actively define the structure of microenvironments and modulate immune cell behavior by conditioning the local and cellular microenvironment (1,2). Human gingival fibroblasts (HGF), 3 the major constituent of gingival connective tissue, have been shown to express immunologic receptors, such as a bacterial pattern recognition receptor CD14 (3,4), TLRs (5), and costimulatory molecule CD40 (1,6) and to produce various cytokines, such as IL-1, IL-6, IL-8, and MCP-1, by interaction with their ligands (3)(4)(5)7). These observations indicate that HGF also actively participate in immune responses and inflammatory processes.…”

Hepatic stellate cells primed with cytokines upregulate inflammation in response to peptidoglycan or lipoteichoic acid

“…[19][20][21][22] Those priming effects were mediated by an upregulation of TLR4 and/or other downstream signaling molecules including MD2, CD14, and MyD88. [20][21][22][23] These results are intriguing with regard to hepatic injury and inflammation because many proinflammatory cytokines, such as TNF-a, are upregulated in patients with liver cirrhosis and liver injury. 24,25 Therefore, we hypothesized that the inflammatory reaction induced by the gram-positive bacterial cell wall components is also enhanced in an injured liver.…”