ADAM-15/Metargidin Mediates Homotypic Aggregation of Human T Lymphocytes and Heterotypic Interactions of T Lymphocytes with Intestinal Epithelial Cells
Laetitia Charrier, Yutao Yan, Hang Thi Thu Nguyen, Guillaume Dalmasso, Christian L. Laboisse, Andrew T. Gewirtz, Shanthi V. Sitaraman, Didier Merlin
Journal of Biological Chemistry
Intestinal epithelial cells (IEC) play an immunoregulatory role in the intestine. This role involves cell-cell interactions with intraepithelial lymphocytes that may also play a role in some enteropathies. The discovery of the RGD motif-containing protein ADAM-15 (a disintegrin and metalloprotease-15) raises the question of its involvement in these cell-cell interactions. Cell adhesion assays were performed using the Jurkat E6. T cell line as a model of T lymphocytes and Caco2-BBE monolayers as
... a model of intestinal epithelia. Our results show that an anti-ADAM-15 ectodomain antibody inhibited the attachment of Jurkat cells on Caco2-BBE monolayers. Overexpression of ADAM-15 in Caco2-BBE cells enhanced Jurkat cell binding, and overexpression of ADAM-15 in Jurkat cells enhanced their aggregation. Mutagenesis experiments showed that both the mutation of ADAM-15 RGD domain or the deletion of its cyto- plasmic tail decreased these cell-cell interactions. Moreover, wound-healing experiments showed that epithelial ADAM-15mediated Jurkat cell adhesion to Caco2-BBE cells enhances the mechanisms of wound repair. We also found that ADAM-15mediated aggregation of Jurkat cells increases the expression of tumor necrosis factor-␣ mRNA. These results demonstrate the following: 1) ADAM-15 is involved in heterotypic adhesion of intraepithelial lymphocytes to IEC as well as in homotypic aggregation of T cells; 2) both the RGD motif and the cytoplasmic tail of ADAM-15 are involved for these cell-cell interactions; and 3) ADAM-15-mediated cell-cell interactions are involved in mechanisms of epithelial restitution and production of pro-inflammatory mediators. Altogether these findings point to ADAM-15 as a possible therapeutic target for prevention of inappropriate T cell activation involved in some pathologies. . 2 Recipient of a research fellowship award from the Crohn and Colitis Foundation of America. 3 The abbreviations used are: IEC, intestinal epithelial cells; IBD, inflammatory bowel disease; TNF, tumor necrosis factor; PBS, phosphate-buffered saline; BCECF-AM, 2Ј,7Ј-bis-(2-carboxyethyl)-5 (and-6) carboxyfluorescein, acetoxymethyl ester; GAPDH, glyceraldehyde-3-phosphate dehydrogenase; Tricine, N-[2-hydroxy-1,1-bis(hydroxymethyl)ethyl]glycine; Vect, vector. by guest on July 25, 2018 http://www.jbc.org/ Downloaded from FIGURE 7. ADAM-15-mediated T cell adhesion to IEC is associated with enhanced wound healing. Caco2-BBE/Vect (A), Caco2-BBE/ADAM-15 (B), Caco2-BBE/SVD (C), and Caco2-BBE/del CT cells (D) were co-seeded with Jurkat cells (solid line) or with inert polystyrene beads used as a control (dotted line), as described under "Materials and Methods." Confluent co-cultures were wounded (arrow) through application of a high voltage pulse of 40-kHz frequency, 4.5-V amplitude, and a 30-s duration. The wound was then allowed to heal, and the level of recovery was assessed by continuous resistance measurements.