ROS/TNF-α Crosstalk Triggers the Expression of IL-8 and MCP-1 in Human Monocytic THP-1 Cells via the NF-κB and ERK1/2 Mediated Signaling.

Nadeem Akhter,Ashraf Al-Madhoun,Hossein Arefanian,Ajit Wilson,Areej Al-Roub,Sardar Sindhu,Fatema Al-Rashed,Rasheed Ahmad,Shihab Kochumon,Reeby Thomas,Fahd Al-Mulla

doi:10.3390/ijms221910519

Nadeem Akhter, Ashraf Al-Madhoun + Show 9 more

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https://doi.org/10.3390/ijms221910519

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Abstract

IL-8/MCP-1 act as neutrophil/monocyte chemoattractants, respectively. Oxidative stress emerges as a key player in the pathophysiology of obesity. However, it remains unclear whether the TNF-α/oxidative stress interplay can trigger IL-8/MCP-1 expression and, if so, by which mechanism(s). IL-8/MCP-1 adipose expression was detected in lean, overweight, and obese individuals, 15 each, using immunohistochemistry. To detect the role of reactive oxygen species (ROS)/TNF-α synergy as a chemokine driver, THP-1 cells were stimulated with TNF-α, with/without H2O2 or hypoxia. Target gene expression was measured by qRT-PCR, proteins by flow cytometry/confocal microscopy, ROS by DCFH-DA assay, and signaling pathways by immunoblotting. IL-8/MCP-1 adipose expression was significantly higher in obese/overweight. Furthermore, IL-8/MCP-1 mRNA/protein was amplified in monocytic cells following stimulation with TNF-α in the presence of H2O2 or hypoxia (p ˂ 0.0001). Synergistic chemokine upregulation was related to the ROS levels, while pre-treatments with NAC suppressed this chemokine elevation (p ≤ 0.01). The ROS/TNF-α crosstalk involved upregulation of CHOP, ERN1, HIF1A, and NF-κB/ERK-1,2 mediated signaling. In conclusion, IL-8/MCP-1 adipose expression is elevated in obesity. Mechanistically, ROS/TNF-α crosstalk may drive expression of these chemokines in monocytic cells by inducing ER stress, HIF1A stabilization, and signaling via NF-κB/ERK-1,2. NAC had inhibitory effect on oxidative stress-driven IL-8/MCP-1 expression, which may have therapeutic significance regarding meta-inflammation.

Highlights

First, we present the clinical data showing that obesity is a positive modulator of IL-8 and MCP-1, and we demonstrate in vitro that the reactive oxygen species (ROS)/Tumor necrosis factor (TNF)-α crosstalk promotes the expression of IL-8 and MCP-1 in human monocytic THP-1 cells through the mechanisms involving endoplasmic reticulum (ER) stress, stabilization of hypoxia-inducible factor (HIF)-1α, and activation of the nuclear factor(NF)-κB and extracellular signal-regulated kinase (ERK)-1/2 signaling pathways
We first determined the changes in adipose expression of IL-8 and MCP-1 in overweight (BMI: 27.80 ± 1.60 kg/m2 ) and obese individuals (BMI: 35.08 ± 3.73 kg/m2 )
The mechanisms addressing inflammatory gene reprogramming under oxidative stress remain poorly understood

Summary

Introduction

Chemotactic cytokines called chemokines play a role in driving the metabolic inflammation associated with obesity, which later leads to the development of type 2 diabetes (T2D), or results in metabolic syndrome. It is important to study the factors and mechanisms of expression of obesity-related chemokines, since these are the early pathophysiologic changes that could later lead to more serious metabolic disorders, such as T2D, atherosclerosis, cardiovascular disease, hepatic steatosis, and metabolic syndrome. These small proteins act as “directional signals” which regulate the trafficking of effector leukocytes to the sites of inflammation.

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