Impact of Toll-like Receptor 4 Expression on Inflammatory Responses Related to Premature Membrane Rupture Induced by Lipopolysaccharide

Discov Med. 2023 Jun;35(176):429-435. doi: 10.24976/Discov.Med.202335176.43.

Abstract

Objective: This study aimed to determine the mechanism through which the expression of Toll-like receptor 4 (TLR4) influences the lipopolysaccharide (LPS)-induced inflammatory response, a condition that is associated with premature rupture of membranes (PROM).

Methods: Human myeloid leukemia mononuclear cells (THP-1) were employed as the experimental model. These cells were treated with LPS and the TLR4 inhibitor CLI-095 and subsequently divided into three groups. A range of assays were utilized, including methyl thiazolyl tetrazole (MTT) assay, real-time fluorescence quantitative polymerase chain reaction (RT-qPCR) for measuring TLR4 and tumor necrosis factor α (TNF-α) mRNA levels, double antibody sandwich enzyme-linked immunosorbent assay (ELISA) for assessing monocyte chemoattractant protein 1 (MCP-1) and matrix metalloproteinase 9 (MMP-9), as well as secretion levels of interleukin (IL)-6 and IL-1β. And western blotting was used to detect the expression of extracellular signal-regulated kinase (ERK) and nuclear factor κB (NF-κB) p65, which are components of the TLR4 downstream signaling pathway.

Results: The LPS-induced proliferation of THP-1 cells was significantly inhibited (p < 0.05) when compared with normal THP-1 cells. Moreover, LPS also promoted TLR4 mRNA and protein expression levels, TNF-α mRNA expression, secretion of inflammatory factors, and phosphorylation of ERK and NF-κB p65 proteins (p < 0.05). On the other hand, administration of the TLR4 inhibitor CLI-095 significantly inhibited the expression of TLR4 mRNA and protein. It also effectively increased the proliferative activity of THP-1 cells and inhibited the secretion of TNF-α and inflammatory factors, as well as the phosphorylation of ERK and NF-κB p65 proteins (p < 0.05).

Conclusions: In summary, suppressing TLR4 expression can mitigate inflammatory responses, thereby reducing the likelihood of premature rupture of membranes during pregnancy, which is often triggered by such inflammation.

Keywords: TNF-α; downstream signal molecule; inflammation; lipopolysaccharide; toll-like receptor.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Humans
  • Interleukin-6
  • Lipopolysaccharides* / toxicity
  • NF-kappa B* / metabolism
  • RNA, Messenger / genetics
  • Toll-Like Receptor 4 / genetics
  • Toll-Like Receptor 4 / metabolism
  • Tumor Necrosis Factor-alpha

Substances

  • ethyl 6-(N-(2-chloro-4-fluorophenyl)sulfamoyl)cyclohex-1-ene-1-carboxylate
  • Interleukin-6
  • Lipopolysaccharides
  • NF-kappa B
  • RNA, Messenger
  • Toll-Like Receptor 4
  • Tumor Necrosis Factor-alpha
  • TLR4 protein, human