Expression of the E-selectin gene in human gingival epithelial tissue

Co-Expression and Functional Interactions of Death Receptor 3 and E-Selectin in Clear Cell Renal Cell Carcinoma

Similar to the behavior of inflamed tubular epithelial cells, clear cell renal cell carcinoma (ccRCC) cells express death receptor 3 (DR3 or TNFSFR25) in situ, and expression increases with tumor grade. Surprisingly, E-selectin, which can be induced in endothelial cells by DR3 signaling, is also expressed by ccRCC cells and increases with tumor grade. In ccRCC organ cultures, addition of tumor necrosis factor-like 1A (TL1A or TNFSF15), the ligand for DR3, activates NF-κB and mitogen-activated protein kinases, induces both DR3 and E-selectin expression in an NF-κB-dependent manner, and promotes cell cycle entry. DR3 immunoprecipitated from ccRCC tissue contains sialyl Lewis X moieties (the ligand recognized by E-selectin), proximity ligation assays reveal DR3, and E-selectin interacts on ccRCC cells. Similar to that with the addition of TL1A, the addition of soluble E-selectin to ccRCC organ cultures activates NF-κB and mitogen-activated protein kinases in ccRCC cells and increases both DR3 and E-selectin expression and cell-cycle entry. In contrast, normal renal tubular epithelium, which poorly expresses DR3, is minimally responsive to either of these ligands. These data suggest a functional role for autocrine/paracrine DR3/E-selectin interactions in ccRCC and its progression, revealing a potential new target for therapeutic intervention.

Evidence for a carbohydrate-binding module (CBM) of Tannerella forsythia NanH sialidase, key to interactions at the host–pathogen interface

Bacterial sialidases cleave terminal sialic acid from a variety of host glycoproteins, and contribute to survival and growth of many human-dwelling bacterial species, including various pathogens. Tannerella forsythia, an oral, Gram-negative, fastidious anaerobe, is a key organism in periodontal disease and possesses a dedicated sialic acid utilisation and scavenging (nan) operon, including NanH sialidase. Here, we describe biochemical characterisation of recombinant NanH, including its action on host-relevant sialoglycans such as sialyl Lewis A and sialyl Lewis X (SLeA/X), and on human cell-attached sialic acids directly, uncovering that it is a highly active broad specificity sialidase. Furthermore, the N-terminal domain of NanH was hypothesised and proved to be capable of binding to a range of sialoglycans and non-sialylated derivatives with Kd in the micromolar range, as determined by steady-state tryptophan fluorescence spectroscopy, but it has no catalytic activity in isolation from the active site. We consider this domain to represent the founding member of a novel subfamily of carbohydrate-binding module (CBM), involved in glycosidase-ligand binding. In addition, we created a catalytically inactive version of the NanH enzyme (FRIP → YMAP) that retained its ability to bind sialic acid-containing ligands and revealed for the first time that binding activity of a CBM is enhanced by association with the catalytic domain. Finally, we investigated the importance of Lewis-type sialoglycans on T. forsythia–host interactions, showing that nanomolar amounts of SLeA/X were capable of reducing invasion of oral epithelial cells by T. forsythia, suggesting that these are key ligands for bacterial–cellular interactions during periodontal disease.

Role of OmpA2 surface regions of Porphyromonas gingivalis in host-pathogen interactions with oral epithelial cells

Outer membrane protein A (OmpA) is a key outer membrane protein found in Gram‐negative bacteria that contributes to several crucial processes in bacterial virulence. In Porphyromonas gingivalis, OmpA is predicted as a heterotrimer of OmpA1 and OmpA2 subunits encoded by adjacent genes. Here we describe the role of OmpA and its individual subunits in the interaction of P. gingivalis with oral cells. Using knockout mutagenesis, we show that OmpA2 plays a significant role in biofilm formation and interaction with human epithelial cells. We used protein structure prediction software to identify extracellular loops of OmpA2, and determined these are involved in interactions with epithelial cells as evidenced by inhibition of adherence and invasion of P. gingivalis by synthetic extracellular loop peptides and the ability of the peptides to mediate interaction of latex beads with human cells. In particular, we observe that OmpA2‐loop 4 plays an important role in the interaction with host cells. These data demonstrate for the first time the important role of P. gingivalis OmpA2 extracellular loops in interaction with epithelial cells, which may help design novel peptide‐based antimicrobial therapies for periodontal disease.

Cell adhesion molecules, the extracellular matrix and oral squamous carcinoma

Carcinomas are characterized by invasion of malignant cells into the underlying connective tissue and migration of malignant cells to form metastases at distant sites. These processes require alterations in cell-cell and cell-extracellular matrix interactions. As cell adhesion molecules play a role in cell-cell and cell-extracellular matrix adhesion and interactions they are involved in the process of tumour invasion and metastases. In epithelial tissues, receptors of the integrin family mediate adhesion to the adjacent matrix whereas cadherins largely mediate intercellular adhesion. These and other cell adhesion molecules such as intercellular adhesion molecule-1, CD44, dystroglycans and selectins, are involved and undergo changes in carcinomas, which provide possible targets for anti-cancer drug treatments. In the extracellular matrix that is associated with tumours, laminin 5, oncofetal fibronectin and tenascin C appear. The degree of expression of some of these moieties indicates prognosis in oral cancer and offer targets for antibody-directed radiotherapy. Metalloproteases which degrade the extracellular matrix are increased in carcinomas, and their activity is necessary for tumour angiogenesis and consequent invasion and metastases. Metalloprotease inhibitors have begun to produce decreases in mortality in clinical trials. This report provides a brief overview of our current understanding of cell adhesion molecules, the extracellular matrix, tumour invasion and metastasis.

Stimulation of adhesion molecule expression in human endothelial cells (HUVEC) by adrenomedullin and corticotrophin

Adrenomedullin (AM) and corticotrophin (ACTH) are both vasoactive peptides produced by a variety of cell types, including endothelial cells. Although AM and ACTH are considered to be important in the control of blood pressure and the response to stress, respectively, their role in inflammation and the immune response has not been clarified. This study shows, with the use of a cell-based ELISA, that AM and ACTH induce cell surface expression of the adhesion molecules E-selectin, VCAM-1, and ICAM-1 on human umbilical vein endothelial cells (HUVEC). Furthermore, this effect appears to be mediated in part via elevation of cAMP, given that both peptides elevate cAMP, the cell-permeable cAMP analog dibutyryl cAMP is able to mimic induction of all three cell adhesion molecules and the effect of AM and ACTH is inhibited by the adenylyl cyclase inhibitor SQ-22536. These findings demonstrate a role for AM and ACTH in the regulation of the immune and inflammatory response.

Glucocorticoid-induced differential expression of the sialylated and nonsialylated Lewis(a) epitopes and respective binding sites in human nasal polyps maintained under ex vivo tissue culture conditions

We characterized the anti-inflammatory effects of budesonide on the expression of adhesion molecules involving Lewis(a) (Le(a)) epitope, its sialylated derivative (sLe(a)), and their respective binding sites in human nasal polyposis. By computer-assisted microscopy, we quantitatively characterized the level of histochemical expression of L- and P-selectins, sialylated and nonsialylated Le(a) epitopes, and their respective binding sites in both surface epithelium and glandular epithelium of human nasal polyps obtained from surgical resection, maintained under ex vivo tissue culture conditions for 24 hours, and treated or not with budesonide. Intercellular adhesion molecule 1 (ICAM-1) and vascular cell adhesion molecule 1 (VCAM-1) were chosen as methodological controls, because data already published in the literature clearly indicated budesonide-mediated effects on ICAM-1 and VCAM-1 levels of expression. The present data show that budesonide significantly modified the levels of expression of ICAM-1 and VCAM-1, and to a lesser extent that of P-selectin, in the surface and glandular epithelia. Budesonide markedly decreased the levels of expression of the binding sites for both Le(a) and sLe(a), while those of Le(a) and sLe(a) remained globally unchanged. In conclusion, the present study documents that glucocorticoid-induced effects can encompass receptors for Le(a) epitopes different from E- and P-selectins on epithelial cells of human nasal polyps.

Cell adhesion molecules and oral cancer

Cell adhesion molecules (CAMs) are found on the surfaces of all cells, where they bind to extracellular matrix molecules or to receptors on other cells. As well as having a structural role, CAMs function as signaling receptors, transducing signals initiated by cellular interactions which regulate many diverse processes, including cell division, migration, and differentiation. Cell adhesion molecules are essential for maintaining stable tissue structure. However, cell adhesion must be dynamic to facilitate the mobility and turnover of cells. In dynamic situations, cells alter their cell-cell and cell-matrix interactions by virtue of altered expression and function of CAMs. The expression of CAMs is normally tightly regulated, thereby controlling cell proliferation, mobility, differentiation, and survival. Many of these processes are misregulated in malignant tumors, and it has been shown that many of the characteristics of tumor cells are attributable to the aberrant expression or function of CAMs. Integrins and E-cadherin are the most important CAMs expressed by stratified squamous epithelium. Altered expression of these molecules has been found in oral carcinoma, where loss of CAM expression is often seen in poorly differentiated lesions. However, up-regulation of certain integrins, such as alphavbeta6, has consistently been found in oral cancer, suggesting that it may play an active role in disease progression.

Adhesion receptors in health and disease

Cell adhesion molecules have been recognized to play a major role in a variety of physiological and pathological phenomena. They determine the specificity of cell-cell binding and the interactions between cells and extracellular matrix proteins. Some of them may also function as receptors that trigger intracellular pathways and participate in cellular processes like migration, proliferation, differentiation, and cell death. The receptors that mediate adhesion between epithelial cells that are discussed in this review include integrins, selectins, the immunoglobulin superfamily members, and cadherins. The intent of this review is to inform the reader about recent advances in cellular and molecular functions of certain receptors, specifically those that are considered important in cell adhesion. We have deliberately not provided all-inclusive detailed information on every molecule, but instead, have presented a generalized overview in order to give the reader a global perspective. This information will be useful in enhancing the reader's understanding of the molecular pathology of diseases and recognizing the potential role of these receptors and ligands as therapeutic agents.

Mechanisms of binding of cutaneous lymphocyte-associated antigen-positive and alphaebeta7-positive lymphocytes to oral and skin keratinocytes

Intraepithelial lymphocytes (IEL) utilize the integrin alphaebeta7 on their surface to bind to E-cadherin on epithelial cells in the gut and breast. In oral mucosa and skin IEL express alphaebeta7 and the cutaneous lymphocyte-associated antigen (CLA) but the mechanisms of adhesion of these subsets to keratinocytes are unknown. Levels of alphaebeta7 and CLA were up-regulated on peripheral blood lymphocytes (PBL) by transforming growth factor-beta (TGF-beta) and interleukin-12 (IL-12), respectively, and both groups of lymphocytes adhered onto oral and skin keratinocytes. Adhesion of IL-12-activated PBL was totally abolished by anti-lymphocyte-associated function antigen type 1 (anti-LFA-1) antibodies but was unaffected by anti-alphaebeta7 antibodies indicating that adhesion of the CLA-positive subset is mediated via LFA-1 interaction with intercellular adhesion molecule-1 (ICAM-1). Adhesion of TGF-beta-activated PBL to E-cadherin-positive oral and skin keratinocytes was partially inhibited by anti-alphaebeta7 antibodies but was unaffected by the blocking antibody E4.6 against E-cadherin which detects the binding site for alphaebeta7-positive lymphocytes in breast and gut epithelium. TGF-beta-activated PBL also bound to an E-cadherin-negative oral keratinocyte cell line and adhesion was inhibited by anti-alphaebeta7 antibodies. These results strongly suggest that in oral epithelium and epidermis alphaebeta7-positive lymphocytes do not bind to E-cadherin and there may be a novel second ligand for the alphaebeta7 integrin.

Cutaneous lymphocyte associated antigen (CLA) and alpha e beta 7 integrins are expressed by mononuclear cells in skin and oral lichen planus

The cutaneous lymphocyte associated- (CLA-) positive subset of lymphocytes appears to migrate preferentially into skin by interacting with E-selectin on vascular endothelium; lymphocytes expressing the alpha e beta 7 integrin accumulate preferentially in the epithelium of the gastrointestinal tract. To determine whether the mononuclear cell population of the oral mucosa resembles that of the skin or intestine, and using lichen planus as a model, the proportions of CLA- and alpha e beta 7-positive cells in the epithelium, lamina propria and peripheral blood were compared by immunostaining and flow cytometry. In both skin and oral lichen planus, selective accumulation of CLA-positive cells was seen in the epithelium but not in the lamina propria. In contrast, large numbers of alpha e beta 7-positive intraepithelial cells were found in oral but not in skin lichen planus. These results show that in terms of CLA and alpha e beta 7 expression there are important differences in the mononuclear cell population of oral mucosa and skin.

Human gingival keratinocytes express E-selectin (CD62E)

OBJECTIVES

E-selectin (CD62E) is an adhesion molecule that participates in the binding of leukocytes to activated blood vascular endothelium. The present study was undertaken to characterise the pattern of E-selectin expression on epithelial cells of the gingival crevice and oral epithelium.

METHODS

A panel of six anti-E-selectin monoclonal antibodies was reacted with cryosections of human gingiva and cytospins of cultured gingival keratinocytes.

RESULTS

Three antibodies raised against leukocyte binding epitopes of the molecule (H4/18, H18/7, 1.2B6) were reactive with gingival keratinocytes, three were negative (4D10, BBA1, BBA2), while all six reacted with endothelial cells. Staining with H18/7 and 1.2B6 was weaker and more variable than with H4/18. In cell culture, levels of E-selectin expression reduced slowly, and were only modestly increased by treatment with exogenous TNF alpha, a known inducer of E-selectin on endothelium.

CONCLUSIONS

E-selectin epitopes are expressed on gingival keratinocytes. These binding epitopes may be involved in the traffic of leukocytes in this tissue compartment.