Outer membrane protein A of Escherichia coli K1 selectively enhances the expression of intercellular adhesion molecule-1 in brain microvascular endothelial cells

Area of Science:

• Neuroscience
• Microbiology
• Immunology

Background:

• Escherichia coli K1 meningitis remains a severe central nervous system disease with persistent high mortality and morbidity.
• The role of E. coli invasion in endothelial cells concerning Intercellular Adhesion Molecule 1 (ICAM-1) expression is not well understood.
• ICAM-1 is crucial for leukocyte trafficking to inflammatory sites in the vascular endothelium.

Purpose of the Study:

• To investigate the effect of E. coli K1 invasion on ICAM-1 expression in human brain microvascular endothelial cells (HBMEC).
• To elucidate the molecular mechanisms underlying E. coli-induced ICAM-1 up-regulation.
• To determine the functional consequence of increased ICAM-1 on immune cell binding.

Main Methods:

• Invasion assays using E. coli K1 and HBMEC.
• Quantitative analysis of ICAM-1 expression.
• Investigation of signaling pathways including PKC-alpha, PI3-kinase, and NF-kappaB.
• Bacterial outer membrane protein A (OmpA) and its receptor Ecgp interaction studies.
• THP-1 cell adhesion assays.

Main Results:

• E. coli K1 invasion selectively up-regulates ICAM-1 expression in HBMEC.
• The interaction between E. coli OmpA and its receptor Ecgp is critical for ICAM-1 up-regulation.
• PKC-alpha, PI3-kinase, and NF-kappaB signaling pathways are involved in this process.
• Increased ICAM-1 expression enhances the binding of THP-1 cells to HBMEC.

Conclusions:

• E. coli K1 invasion triggers a localized increase in ICAM-1 expression in HBMEC.
• This up-regulation is mediated by a novel interaction between OmpA and Ecgp, dependent on specific signaling pathways.
• The findings provide insights into the pathogenesis of E. coli K1 meningitis and potential therapeutic targets.