Resolvins Decrease Oxidative Stress Mediated Macrophage and Epithelial Cell Interaction through Decreased Cytokine Secretion

Abstract

BackgroundInflammation is a key hallmark of ALI and is mediated through ungoverned cytokine signaling. One such cytokine, interleukin-1beta (IL-1β) has been demonstrated to be the most bioactive cytokine in ALI patients. Macrophages are the key players responsible for IL-1β secretion into the alveolar space. Following the binding of IL-1β to its receptor, “activated” alveolar epithelial cells show enhanced barrier dysfunction, adhesion molecule expression, cytokine secretion, and leukocyte attachment. More importantly, it is an important communication molecule between the macrophage and alveolar epithelium. While the molecular determinants of this inflammatory event have been well documented, endogenous resolution processes that decrease IL-1β secretion and resolve alveolar epithelial cell activation and tissue inflammation have not been well characterized. Lipid mediator Aspirin-Triggered Resolvin D1 (AT-RvD1) has demonstrated potent pro-resolutionary effects in vivo models of lung injury; however, the contribution of the alveoli to the protective benefits of this molecule has not been well documented. In this study, we demonstrate that AT-RvD1 treatment lead to a significant decrease in oxidant induced macrophage IL-1β secretion and production, IL-1β-mediated cytokine secretion, adhesion molecule expression, leukocyte adhesion and inflammatory signaling.MethodsTHP-1 macrophages were treated with hydrogen peroxide and extracellular ATP in the presence or absence of AT-RvD1 (1000–0.1 nM). A549 alveolar-like epithelial cells were treated with IL-1β (10 ng/mL) in the presence or absence of AT-RvD1 (0.1 μM). Following treatment, cell lysate and cell culture supernatants were collected for Western blot, qPCR and ELISA analysis of pro-inflammatory molecules. Functional consequences of IL-1β induced alveolar epithelial cell and macrophage activation were also measured following treatment with IL-1β ± AT-RvD1.ResultsResults demonstrate that macrophages exposed to H2O2 and ATP in the presence of resolvins show decreased IL-1β production and activity. A549 cells treated with IL-1β in the presence of AT-RvD1 show a reduced level of proinflammatory cytokines IL-6 and IL-8. Further, IL-1β-mediated adhesion molecule expression was also reduced with AT-RvD1 treatment, which was correlated with decreased leukocyte adhesion. AT-RvD1 treatment demonstrated reduced MAP-Kinase signaling. Taken together, our results demonstrate AT-RvD1 treatment reduced IL-1β-mediated alveolar epithelial cell activation. This is a key step in unraveling the protective effects of resolvins, especially AT-RvD1, during injury.

Macrophages and the Recovery from Acute and Chronic Inflammation

“…One function of resolvins appears to be halting the infiltration of poly-morphonuclear leukocytes to sites of infections once they are no longer needed (86). A recent study demonstrated that macrophages stimulated in the presence of resolvins, specifically RvD1, had decreased production of IL-1β, IL-6, and IL-8 (87). This was due to lower caspase-1 activation and signaling through GPR32 on the macrophage surface (87, 88).…”

“…A recent study demonstrated that macrophages stimulated in the presence of resolvins, specifically RvD1, had decreased production of IL-1β, IL-6, and IL-8 (87). This was due to lower caspase-1 activation and signaling through GPR32 on the macrophage surface (87, 88). Additionally, RvD1 attenuates Th1 cytokine production by classically activated macrophages and upregulates arginase I expression (89).…”

Inhibition of endotoxin-induced airway epithelial cell injury by a novel family of pyrrol derivates

“…27 Numerous experimental studies have used human A549 alveolar and BEAS-2B bronchial epithelial cell lines to examine the acute lung inflammatory response induced by LPS, as an acceptable, validated, and suitable in vitro airway epithelial injury model based on the initial steps of the development of sepsis and ARDS [11][12][13][14][15][16]25,[28][29][30] and continue being extensively used. [31][32][33][34][35] We selected E. coli LPS because it has been used in most endotoxin-induced lung injury models 36,37 and LPS is a key pathogen recognition molecule for sepsis 27 that induces apoptosis in lung cells. 38 Previous reports examining the efficacy of molecules on the LPS-induced activation of inflammatory markers in the lung, or before evaluating the potential in vivo anti-inflammatory properties, have used a similar in vitro epithelial cell injury model to the one we used.…”

“…Second, we did not use primary alveolar epithelial cells; however, there is a plethora of published studies validating the use of human BEAS-2B and A549 cells as an acceptable model of epithelial cell injury and for studying the LPS-induced effects in the airway epithelium. [11][12][13][14][15][16]25,[28][29][30][31][32][33][34][35] Third, further studies are needed to elucidate whether there are other mechanisms by which the pyrrol compound DTA0118 elicits its anti-inflammatory and antiapoptotic activities. Fourth, TLR4, Ikβα, and β-actin were not adjusted for the cell number.…”

Frontline Science: Specialized proresolving lipid mediators inhibit the priming and activation of the macrophage NLRP3 inflammasome

“…Among the SPM family, in the current study, we focused our attention on resolvins of the D‐series and in particular in resolvin (Rv) D1 and RvD2, which are the most widely characterized and their receptors have been identified and cloned . In addition, these SPMs potently reduce the secretion of proinflammatory cytokines by activated macrophages, and more specifically are capable of reducing the expression of IL‐1β at the mRNA level in THP‐1 monocytic cells, burn wound neutrophils , and vascular smooth muscle cells as well as to reduce the levels of mature IL‐1β protein in adipose tissue, liver, and THP‐1 macrophages . However, the molecular determinants underlying the modulatory actions of these SPMs on IL‐1β levels have not yet been characterized.…”