Eikenella corrodens lipopolysaccharide stimulates the pro‐atherosclerotic response in human coronary artery endothelial cells and monocyte adhesion

Abstract

Eikenella corrodens is a gram‐negative bacterium, and although primarily associated with periodontal infections or infective endocarditis, it has been identified in coronary atheromatous plaques. The effect of its lipopolysaccharide (LPS) on human coronary artery endothelial cells (HCAECs) is unknown. Our aim was to examine the mechanism underlying the inflammatory response in HCAECs stimulated with E. corrodens‐LPS and to evaluate monocyte adhesion. Endothelial responses were determined by measuring the levels of chemokines and cytokines using flow cytometry. The surface expression of intercellular adhesion molecule 1 (ICAM‐1) was determined using a cell‐based ELISA, and the adhesion of THP‐1 monocytes to HCAECs was also monitored. The involvement of toll‐like receptors (TLRs) 2 and 4 was examined using TLR‐neutralizing antibodies, and activation of extracellular signal‐regulated kinase (ERK)1/2 and nuclear factor‐kappa B (NF‐κB) p65 were measured by western blotting and ELISA, respectively. Eikenella corrodens‐LPS increased secretion of interleukin‐8 (IL‐8), monocyte chemotactic protein 1 (MCP‐1), and granulocyte–macrophage colony‐stimulating factor (GM‐CSF), and expression of ICAM‐1 on the surface of HCAECs, consistent with the increased adhesion of THP‐1 cells. Moreover, E. corrodens‐LPS interacted with TLR4, a key receptor able to maintain the levels of IL‐8, MCP‐1, and GM‐CSF in HCAECs. Phosphorylation of ERK1/2 and activation of NF‐κB p65 were also increased. The results indicate that E. corrodens‐LPS activates HCAECs through TLR4, ERK, and NF‐κB p65, triggering a pro‐atherosclerotic endothelial response and enhancing monocyte adhesion.

Differential responses of endothelial cells on three‐dimensional scaffolds to lipopolysaccharides from periodontopathogens

“…Similarly, we showed that HCAECs in both 2D and 3D models exhibit an innate inflammatory cellular response to Aa‐LPS that might be related to the adhesion of monocytes. This response is similar to that induced in HCAECs by LPS from E. corrodens (Viafara‐Garcia et al, ) . Therefore, these results suggest that oral pathogens other than P. gingivalis strains have the capacity to induce proatherosclerotic endothelial dysfunction.…”

“…Evaluation of the adhesion of THP‐1 monocytes (ATCC ® ) to cultured HCAECs was carried out following a previously described procedure (Viafara‐Garcia et al, ). The 3D and 2D cultures were established by seeding 2 × 10 4 HCAECs on type I collagen scaffolds or in 96‐well plates, respectively, and incubating (5% CO 2 , 37°C) until cell confluence was reached.…”

“…The evidence indicates that the interactions between bacteria and ECs play an important role in the pathogenesis of endothelial dysfunction. However, in vitro studies with EC cultures have shown that Pg‐LPS does not induce strong expression of markers of the inflammatory response, while LPS from Aggregatibacter actinomycetemcomitans (Aa) and Eikenella corrodens does (Erridge, Spickett, & Webb, ; Gualtero et al, ; Ho, Guo, Chunga, Goodwin, & Xie, ; Kebschull, Demmer, & Papapanou, ; Viafara‐Garcia, Gualtero, Avila‐Ceballos, & Lafaurie, ). In these two‐dimensional (2D) models, cultured ECs are not exposed to the components of the basement membrane that underlie the endothelium.…”

Periodontal pathogens and their role in cardiovascular outcome

“…E. corrodens is among the bacteria frequently isolated from subgingival pockets in patients with severe periodontitis (Puig‐Silla, Montiel‐Company, Dasi‐Fernandez, & Almerich‐Silla, ). In an in vitro study, lipopolysaccharide of E. corrodens was proven to induce a pro‐atherosclerotic endothelial response and enhancing monocyte adhesion via toll‐like receptor 4, extracellular signal‐regulated kinase, and nuclear factor‐κB and p65 (Viafara‐Garcia, Gualtero, Avila‐Ceballos, & Lafaurie, ). This would imply that E. corrodens contribute to promote the atherosclerotic process by triggering endothelial inflammation.…”

Aggregatibacter actinomycetemcomitans induces a proatherosclerotic response in human endothelial cells in a three‐dimensional collagen scaffold model

“…However, little is known about the mechanisms used by periodontal pathogenic bacteria to damage the cardiovascular arterial endothelium. Human coronary artery endothelial cells (HCAECs) stimulated in vitro with lipopolysaccharide (LPS) or periodontopathogenic bacteria induce the secretion of cytokines and chemokines that favor the adhesion of monocytes to the activated endothelium (Gualtero et al, 2017;Viafara-Garcia et al, 2018).…”