Immunosuppression-induced bronchial epithelial-mesenchymal transition: a potential contributor to obliterative bronchiolitis.

OBJECTIVE: Obliterative bronchiolitis is the predominant histopathologic finding in patients with chronic rejection after lung transplant. This fibroproliferative transformation within small airways of lung allograft is poorly understood; however, studies suggest epithelial-mesenchymal transition plays a role. Transplant immunosuppressive therapy has been shown to cause epithelial-mesenchymal transition in renal tubular epithelial cells, with subsequent fibrosis. This study explored whether immunosuppressive therapy contributes to epithelial-mesenchymal transition in airway epithelial cells. METHODS: Bronchial epithelial cell line RL-65 was treated 3 to 5 days with several immunosuppressive agents, including cyclosporine (INN ciclosporin), tacrolimus, azathioprine, mycophenolic acid, sirolimus, prednisone, and transforming growth factor ß1 as control. We then analyzed cells for presence of mesenchymal morphology and protein markers. RESULTS: Treatment with cyclosporine, azathioprine, mycophenolate, and sirolimus resulted in elongated and irregular cell shape, and all but azathioprine showed loss of cell-cell adhesions relative to vehicle-treated cells. Expressions of extracellular matrix proteins, fibronectin and collagen, along with mesenchymal marker, vimentin, were significantly upregulated. Immunofluorescence showed loss of E-cadherin at cell membranes and cytoskeletal rearrangements typical of epithelial-mesenchymal transition. These immunosuppressive agents also increased transforming growth factor produced by cells; however, tacrolimus- and prednisone-treated cells maintained epithelial morphology, baseline levels of matrix protein expression, and transforming growth factor production levels. CONCLUSIONS: Overall, we found that certain immunosuppressive agents may contribute to partial epithelial-mesenchymal transition in bronchial epithelial cells, specifically increasing production of excessive extracellular matrix proteins. This may provide novel insights into the pathogenesis of obliterative bronchiolitis after lung transplant.

Genomic characterization of the inflammatory response initiated by surgical intervention and the effect of perioperative cyclooxygenase 2 blockade.

OBJECTIVE: There are potentially deleterious sequelae of the physiologic response to surgical intervention. Some inflammatory cytokines can act as tumor growth factors, angiogenic and metastatic promoters, or both. Modulation of negative effects could improve outcomes from surgical intervention. The effects of surgical intervention on gene expression have not been fully elucidated. We assayed gene expression changes in an animal model of thoracotomy versus a sham operation and evaluated the ability of a cyclooxygenase inhibitor, celecoxib, to mediate these changes. METHODS: Sixty adult male BALB/c mice were randomized into one of 3 experimental groups: sham operation with anesthesia only, thoracotomy incision, and thoracotomy incision with perioperative celecoxib administration. Six hours after surgical intervention, the animals were killed, and blood was collected. RNA pools from each group were labeled and hybridized to Mouse Whole Genome Microarrays. Gene expression profiles were analyzed to determine the effect of both surgical intervention and celecoxib treatment. RESULTS: Surgical intervention initiated a robust gene expression response. We identified 867 transcripts that were found to be statistically significant (corrected P < .05) and differentially expressed at least 2-fold in response to surgical intervention. Celecoxib had a profound effect on this response, preserving close to baseline levels of expression for most of those genes. CONCLUSIONS: Surgical intervention has a dramatic effect on the expression of genes related to the inflammatory response. Perioperative treatment with a cyclooxygenase 2 inhibitor abated many of these changes and might counteract many of the negative effects of the response to surgical intervention.