Anti-inflammatory effects of methoxyphenolic compounds on human airway cells

Human airway cells were stimulated with TNF-α in the presence or absence of 4-substituted methoxyphenols and resveratrol. The expression of various cytokines was measured by qPCR, ELISAs, and protein arrays. Reactive oxygen species (ROS) production was measured with a reactive fluorescent probe (3',6'-diacetate-2',7'-dichlorofluorescein). Activation of NF-κB was measured by nuclear translocation and phosphorylation. Ribonuclear protein association with mRNA was assessed with a biotin-RNA affinity isolation assay.Multiple inflammatory mediators were inhibited by methoxyphenols, including: CCL2, CCL5, IL-6, IL-8, ICAM-1, MIF, CXCL1, CXCL10, and Serpin E1. IC50 values were obtained for each compound that showed significant anti-inflammatory activity: diapocynin (20.3 μM), resveratrol (42.7 μM), 2-methoxyhydroquinone (64.3 μM), apocynin (146.6 μM), and 4-amino-2-methoxyphenol (410 μM). The anti-inflammatory activity did not correlate with inhibition of reactive oxygen species production or NF-κB activation. However, methoxyphenols inhibited binding of the RNA-binding protein HuR to mRNA, indicating that they may act post-transcriptionally.Methoxyphenols demonstrate anti-inflammatory activity in human airway cells. More potent compounds that act via similar mechanisms may have therapeutic potential as novel anti-inflammatory agents.The airway epithelium plays a crucial role in the pathogenesis of asthma, chronic obstructive pulmonary disease, and other inflammatory lung diseases. By serving as a key interface between the host and environment, the airway participates in activation of innate immunity and production of cytokines and other inflammatory mediators in response to microbes, allergens, pollutants, and other inflammatory stimuli [1,2]. As such, the airway epithelium is a prime target for anti-inflammatory agents.The production of cytokines from the airway epithelium has been shown to play an important role in regulating inflammation associated with respiratory dis