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- Title
Moraxella catarrhalis lipooligosaccharide selectively upregulates ICAM-1 expression on human monocytes and stimulates adjacent naïve monocytes to produce TNF-α through cellular cross-talk.
- Authors
Hang Xie; Xin-Xing Gu
- Abstract
To elucidate the role of Moraxella catarrhalis lipooligosaccharide (LOS) in otitis media with effusion (OME), the effects of LOS on adhesion antigens of human monocytes were investigated. M. catarrhalis LOS selectively enhanced intercellular adhesion molecule 1 (ICAM-1 or CD54) expression on human monocytes by significantly increasing both the surface expression intensity and the percentage of ICAM-1+ cells. ICAM-1 upregulation on human monocytes by the LOS required surface CD14, TLR4, NF-κB p65 and c-Jun N-terminal kinase (JNK) activity. Our study also revealed that the LOS-induced surface ICAM-1 expression was partially mediated through a TNF-α dependent autocrine mechanism and could be further augmented by lipopolysaccharide-binding protein in serum. In addition, M. catarrhalis LOS also stimulated human monocytes to produce pro-inflammatory cytokines in both TLR4- and CD14-dependent pathways. Our results also indicated that enhanced surface ICAM-1 expression on monocytes may hinder their adherence to the lung epithelial monolayer. Furthermore, the LOS-activated human monocytes secreted a significantly high level of IL-8, and could stimulate adjacent naïve monocytes to produce TNF-α which was partially mediated via membrane ICAM-1 and IL-8/IL-8RA. These results suggest that M. catarrhalis LOS could induce excessive middle ear inflammation through a cellular cross-talk mechanism during OME.
- Subjects
MICROBIOLOGY; MONOCYTES; CYTOKINES; OTITIS media; CELL adhesion molecules; CARRIER proteins; SERUM; BLOOD plasma; ADSORPTION (Chemistry)
- Publication
Cellular Microbiology, 2008, Vol 10, Issue 7, p1453
- ISSN
1462-5814
- Publication type
Article
- DOI
10.1111/j.1462-5822.2008.01138.x