Endothelin Receptor Antagonists Attenuate the Inflammatory Response of Human Pulmonary Vascular Smooth Muscle Cells to Bacterial Endotoxin

Abstract

Bacterial infections induce exacerbations in chronic lung diseases, e.g., chronic obstructive pulmonary disease (COPD), by enhancing airway inflammation. Exacerbations are frequently associated with right heart decompensation and accelerate disease progression. Endothelin receptor antagonists (ERAs) might have therapeutic potential as pulmonary vasodilators and anti-inflammatory agents, but utility in exacerbations of chronic lung diseases is unknown. We hypothesized that cytokine releases induced by lipopolysaccharide (LPS), the major bacterial trigger of inflammation, are reduced by ERAs in pulmonary vascular smooth muscle cells (PVSMCs). Ex vivo cultivated human PVSMCs were preincubated with the endothelin-A-receptor selective inhibitor ambrisentan, with the endothelin-B-receptor selective inhibitorhexanoate], or with the dual blocker bosentan before stimulation with smooth LPS (S-LPS), rough LPS (Re-LPS), or a mixture of long and short forms (M-LPS). Expression of cytokines and LPS receptors (TLR4, CD14) were analyzed via enzyme-linked immunosorbent assay (ELISA) and/or quantitative reverse transcriptase polymerase chain reaction (qRT-PCR). All LPS forms induced interleukin (IL)-6-, IL-8-, and granulocyte macrophage-colony stimulating factor (GM-CSF) release. Bosentan and BQ788 inhibited M-LPS-induced release of all cytokines and soluble CD14 (sCD14) but not TLR4 expression. Ambrisentan blocked M-LPS-induced IL-6 release but not IL-8, GM-CSF, or LPS receptors. IL-8 release induced by S-LPS, which requires CD14 to activate TLR4, was blocked by bosentan and BQ788. IL-8 release induced by Re-LPS, which does not require CD14 to activate TLR4, was insensitive to both bosentan and BQ788. In conclusion, PVSMCs contribute to inflammation in bacteriainduced exacerbations of chronic lung diseases. Inhibition of the endothelin-B receptor suppresses cytokine release induced by long/smooth LPS attributable to sCD14 downregulation. ERAs, particularly when targeting the endothelin-B receptor, might have therapeutic utility in exacerbations of chronic lung diseases.

Challenges and opportunities in treating inflammation associated with pulmonary hypertension

“…There are several studies that show that bosentan inhibits endothelin 1-induced IFNgamma release from CD4+ cells (105) or endotoxin-stimulated cytokine release from pulmonary arterial smooth muscle cells (106), however, Brun et al assessed the systemic inflammatory response in congenital heart disease -associated PAH patients and found no effect of bosentan treatment inflammation (107). …”

Ameliorative Effect of a Selective Endothelin ETAReceptor Antagonist in Rat Model of L-Methionine-induced Vascular Dementia

“…Reduced levels of NO contribute to increased vascular tone, inflammation, platelet aggregation and oxidative stress which all are central features of atherosclerosis and hyperhomocysteinemia [17]. Endothelin receptor antagonists including ambrisentan are noted to exert their anti-inflammatory actions along with reduction in reactive oxygen species (ROS) generation which are subsequently responsible for endothelial dysfunction [18,19]. ET receptor antagonists have also been shown to provide a beneficial effect in various cerebrovascular disorders such as moyamoya disease [20], ischemic stroke [21] and subarachnoid hemorrhage [22].…”

The multifaceted role of c-di-AMP signaling in the regulation of Porphyromonas gingivalis lipopolysaccharide structure and function

“…To further assess the impact of dysregulated c-di-AMP signaling on this characteristic of the LPS profile, we conducted a gel mobility shift assay to assess the mobility of LPS samples, as well as the interaction between LPS and polymyxin B under “native” electrophoretic conditions. Polymyxin B, a positively charged antibiotic, is a widely used component in LPS binding studies ( Knobloch et al., 2013 ; Manioglu et al., 2022 ). The comparative analysis of relative mobility shifts between polymyxin B-treated and untreated LPS samples run on a native gel is depicted in Figure 7B and Supplementary Table 5 .…”