Ultrastructural localization of lectin-binding sites on the surface of the guinea pig conjunctival epithelium

Dual Regulation of L-Selectin-Mediated Leukocyte Adhesion by Endothelial Surface Glycocalyx

Endothelial surface glycocalyx (ESG) is a carbohydrate-rich, gel-like layer found on vascular endothelium, serving critical functions in mechanotransduction of blood flows, maintenance of the endothelial permeability, and the control of leukocyte adhesion and inflammation. This study aimed to clarify the role of ESG in the adhesion between leukocytes and Human Umbilical Vein Endothelial Cells (HUVECs) under resting or inflammatory conditions. Using an atomic force microscopy-based single-cell adhesion assay, we directly quantified the detachment force and work perpendicular to the cell membrane. Detachment force and work were measured for every separation event of a leukocyte from a HUVEC with ESG, or with the major ESG glycosaminoglycan components, heparan sulfate (HS) and hyaluronic acid (HA) removed. For the resting HUVECs, when HS and/or HA were removed, the detachment force and work increased dramatically. For the HUVECs activated by inflammatory cytokine tumor necrosis factor alpha, we observed increases in the detachment force and work compared to the resting HUVECs, and removal of HS and/or HA resulted in significant decreases in the detachment force and work. The results demonstrate that the ESG layer serves a dual function: (1) on resting endothelium, it prevents leukocyte adhesion, and (2) under inflammatory conditions, it participates in endothelial-leukocyte interactions with molecules such as selectins.

Characterisation of 20-kDa lectin-spermagglutinin from Arum maculatum that prevents Chlamydia pneumoniae infection of L-929 fibroblast cells

A novel lectin from the root of Arum maculatum was isolated by saline extraction and purified by cold ethanol precipitation and subsequent fractionation on Superose 6 column. The lectin named A. maculatum agglutinin is a non-glycosylated protein with 20-kDa molecular mass agglutinating human ejaculated spermatozoa, but not human erythrocytes. The agglutination was blocked in the presence of N-acetylneuraminic acid indicating that the lectin is sialoglycoprotein specific. Chlamydia pneumoniae strain AR-39 showed considerable potential to grow in murine L-929 fibroblast cells. Pretreatment of the cell monolayers with purified lectin reduced the entry and intracellular replication of C. pneumoniae. These results suggest that the isolated lectin prevents attachment by binding to a C. pneumoniae specific sialoglycoprotein receptor expressed on the surface of L-929 fibroblast cells.