Involvement of endothelial cell adhesion molecules in the development of anti-Thy-1 nephritis.

To study an involvement of glomerular endothelial cells in the development of anti-Thy-1 nephritis, we examined the expression of endothelial cell adhesion molecules during the course of this model. Ribonuclease protection assay elucidated that expression of mRNA for intercellular adhesion molecule-1 (ICAM-1) was markedly enhanced in the glomeruli with a peak at 2 h (6.5-fold, p < 0.05) after the anti-Thy-1 antibody injection when mesangial cell lysis was recognized and IL-1beta mRNA expression was induced in the glomeruli. The glomerular ICAM-1 was predominantly localized in the endothelial cells and was intensely immunostained at day 1 in the glomerular endothelial cells. In contrast, platelet endothelial cell adhesion molecule-1 (PECAM-1) and vascular endothelial-cadherin mRNA expression increased gradually with a peak at day 6 (2.6-fold (p < 0.05) and 4.2-fold (p < 0.05), respectively) in the glomeruli with mesangial proliferative lesion. PECAM-1 was also immunolocalized in the glomerular endothelial cells and the immunoreactivity was greatly enhanced at day 6. Glomerular expression of vascular cell adhesion molecule-1 and endothelial leukocyte adhesion molecule-1 (E-selectin) was unchanged at a low level during the course of anti-Thy-1 nephritis. Blocking of ICAM-1 by administration of anti-ICAM-1 antibody showed significant decrease in the number of polymorphonuclear leukocytes accumulating in the glomeruli by 45.7% (9.4 +/- 0.2 vs. 5.1 +/- 0.1 per glomerular cross section, p < 0.01) at 2 h. These results suggest a significant involvement of glomerular endothelial cells in the development and repair of anti-Thy-1 nephritis via direct or indirect intercellular interactions between mesangial cells and glomerular endothelial cells.

Localization of olfactomedin-related glycoprotein isoform (BMZ) in the golgi apparatus of glomerular podocytes in rat kidneys.

Agene encoding olfactomedin-related glycoprotein was isolated from rat glomerulus despite its prior identification as a neuron-specific gene. The mRNA expression was remarkably intense in renal glomerulus and brain and faint in the lung and eye among rat systemic organs. Although the brain contained four mRNA variants (AMY, AMZ, BMY, and BMZ) transcribed from a single gene, the glomerulus, lung, and eye expressed only two variants (BMZ and BMY). The glycoprotein was intensely immunolocalized in glomerular podocytes and neurons by using an antibody against synthetic peptide of the M region, but weak in endothelial cells of the kidney and lung. Bronchiolar epithelial cells in the lung, and ciliary, corneal, and iris epithelial cells in the eye were also stained. Immunogold electron microscopy revealed selective localization of olfactomedin-related glycoprotein at the Golgi apparatus in podocytes. In glomerular culture, the staining was also intense at a juxtanuclear region in synaptopodin-positive epithelial cells of irregular shape (phenotypic feature of podocytes), whereas it was weak in synaptopodin-negative ones of cobblestone-like appearance (phenotypic feature of parietal epithelial cells of Bowman's capsule). Interestingly, Western blot analysis identified an intense band corresponding to BMZ isoform and another faint band corresponding to BMY isoform in the glomerulus, whereas the intensity of these two bands were nearly equal in the lung and eye. In the brain, four bands corresponding to four isoforms were observed apparently. Computer sequence analysis predicted coiled-coil structures in the secondary structure of the glycoprotein similar to those in Golgi autoantigens, suggesting significant roles in the unique functions of the Golgi apparatus in rat podocytes and neurons.