Mycobacterium-induced transmesothelial migration of monocytes into pleural space: Role of intercellular adhesion molecule-1 in tuberculous pleurisy

The pleural mesothelium is a dynamic cellular membrane with multiple key functions, it plays a pivotal role in pleural inflammation through its release of several cytokines and the expression of cell-surface molecules. The expression of intercellular adhesion molecule (ICAM)-1 in the pleural mesothelium of patients with active pleural tuberculosis and the role of ICAM-1 in monocyte transmigration across pleural mesothelium during tuberculous inflammation was investigated. Results indicate pleural mesothelial cells (PMCs) express ICAM-1 in tuberculous pleuritis. When PMCs were stimulated with bacille Calmette-Guerin (BCG) in vitro, they expressed ICAM-1 in a time-dependent manner. Monocyte transmigration was higher across PMC monolayers that had been stimulated with BCG. Blocking ICAM-1 on BCG-activated PMC monolayers inhibited monocyte transmigration against chemotactic gradient generated by macrophage inflammatory protein 1-alpha or monocyte chemotactic protein-1. These results indicate that ICAM-1 expression in PMCs facilitates monocyte transmigration during tuberculous pleural inflammation.