Oxidative stress induces expression of the toll-like receptors (TLRs) 2 and 4 in the human peripheral blood mononuclear cells: Implications for metabolic inflammation

Nadeem Akhter, Ashraf Madhoun, Hossein Arefanian, Ajit Wilson, Shihab Kochumon, Reeby Thomas, Steve Shenouda, Fahd Al-Mulla, Rasheed Ahmad, Sardar Sindhu

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)

Abstract

BACKGROUND/AIMS: Innate immune toll-like receptors (TLRs) are emerging as nutrient sensors. Oxidative stress in the adipose tissue in obesity acts as a critical early trigger of altered pathophysiology. TLR2/TLR4 adipose upregulation has been associated with insulin resistance in humans; however, it remains unclear whether oxidative stress can modulate expression of TLR2/4 and related immune-metabolic regulators (IRF3/5) in immune cells. We, therefore, assessed their expression along with proinflammatory cytokines in the human PBMC following induction of oxidative stress.

METHODS: PBMC were isolated from blood of healthy donors using Ficoll-Paque method and cells were treated with H 2O 2 to induce oxidative stress. ROS was measured by DCFH-DA assay. Target gene and protein expression was determined using real-time RT-PCR and flow cytometry/confocal microscopy, respectively. TLR2/4 expression by H 2O 2 in presence of ROS-inhibitors or leptin/LPS/fatty acids was also assessed. Expression of phosphorylated/total ERK1/2, c-Jun, p38, and NF-κB was determined by western blotting. The data (mean±SEM) were compared using unpaired student's t-test or ANOVA; all P-values <0.05 were considered significant.

RESULTS: TLR2/4 mRNA/protein expression was elevated by oxidative stress in PBMC compared to controls (P<0.001). This induction was abrogated by apocynin/N-acetyl cysteine treatments (P<0.01). H 2O 2-induced TLR2/4 gene expression was further enhanced by leptin, LPS, oleate, or palmitate (P<0.05). Oxidative stress also promoted expression of IRF3/5 and proinflammatory cytokines including IFN-γ, IL-1β, IL-6, TNF-α, and MCP-1/CCL2. This oxidative stress in PBMC involved MAPK/NF-κB dependent signaling.

CONCLUSION: Taken together, oxidative stress upregulates expression of TLR2/4, IRF3/5 and signature proinflammatory cytokines in PBMC, involving MAPK/NF-κB dependent signaling, all of which may have implications for metabolic inflammation.

Original languageEnglish
Pages (from-to)1-18
Number of pages18
JournalCellular Physiology and Biochemistry
Volume53
Issue number1
DOIs
Publication statusPublished - 1 Jan 2019

Keywords

  • Cells, Cultured
  • Humans
  • Inflammation/genetics
  • Interferon Regulatory Factor-3/genetics
  • Interferon Regulatory Factors/genetics
  • Leukocytes, Mononuclear/metabolism
  • Oxidative Stress
  • Reactive Oxygen Species/metabolism
  • Toll-Like Receptor 2/genetics
  • Toll-Like Receptor 4/genetics
  • Up-Regulation

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