Non-toxic sulfur inhibits LPS-induced inflammation by regulating TLR-4 and JAK2/STAT3 through IL-6 signaling

Mol Med Rep. 2021 Jul;24(1):485. doi: 10.3892/mmr.2021.12124. Epub 2021 Apr 28.

Abstract

Janus kinase 2 (JAK2) and STAT3 signaling is considered a major pathway in lipopolysaccharide (LPS)‑induced inflammation. Toll‑like receptor 4 (TLR‑4) is an inflammatory response receptor that activates JAK2 during inflammation. STAT3 is a transcription factor for the pro‑inflammatory cytokine IL‑6 in inflammation. Sulfur is an essential element in the amino acids and is required for growth and development. Non‑toxic sulfur (NTS) can be used in livestock feeds as it lacks toxicity. The present study aimed to inhibit LPS‑induced inflammation in C2C12 myoblasts using NTS by regulating TLR‑4 and JAK2/STAT3 signaling via the modulation of IL‑6. The 3‑(4,5‑dimethylthiazol‑2‑yl)‑2,5‑diphenyltetrazolium bromide assay was conducted to analyze cell viability and reverse transcription polymerase chain reaction and western blotting performed to measure mRNA and protein expression levels. Chromatin immunoprecipitation and enzyme‑linked immunosorbent assays were used to determine the binding activity of proteins. The results indicated that NTS demonstrated a protective effect against LPS‑induced cell death and inhibited LPS‑induced expression of TLR‑4, JAK2, STAT3 and IL‑6. In addition, NTS inhibited the expression of nuclear phosphorylated‑STAT3 and its binding to the IL‑6 promoter. Therefore, NTS may be a potential candidate drug for the treatment of inflammation.

Keywords: IL-6; Janus kinase 2; STAT3; Toll-like receptor 4; non-toxic sulfur.

MeSH terms

  • Animals
  • Cell Line
  • Cytokines / metabolism
  • Gene Expression Regulation
  • Inflammation / chemically induced
  • Inflammation / drug therapy*
  • Inflammation / genetics
  • Interleukin-6 / metabolism*
  • Janus Kinase 2 / genetics
  • Janus Kinase 2 / metabolism*
  • Lipopolysaccharides / adverse effects*
  • Mice
  • STAT3 Transcription Factor / genetics
  • STAT3 Transcription Factor / metabolism*
  • Signal Transduction / drug effects*
  • Sulfur / pharmacology*
  • Toll-Like Receptor 4 / genetics
  • Toll-Like Receptor 4 / metabolism*

Substances

  • Cytokines
  • Interleukin-6
  • Lipopolysaccharides
  • STAT3 Transcription Factor
  • Stat3 protein, mouse
  • Tlr4 protein, mouse
  • Toll-Like Receptor 4
  • Sulfur
  • Jak2 protein, mouse
  • Janus Kinase 2

Grants and funding

The present study was supported by Nara Bio Co., Ltd., Republic of Korea, in 2018 and by the Cooperative Research Program for Agriculture Science and Technology Development (project no. PJ01325702) and by the National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIT; grant no. 2018R1C1B6006146).