Cecilia Prêle

Mesothelial cells are specialized cells that cover the pleural surface as well as other serosal surfaces of most internal organs. Mesothelial cells can have dierent phenotypes which are likely to reect dierences in the functions of parietal and visceral pleura, as well as their activational state, particularly following injury. Mesothelial cells synthesize and secrete glycosaminoglycans and surfactant1 to provide lubrication between parietal and visceral pleura and play critical roles in the maintenance of pleural homeostasis in response to stimuli: mechanical injury, inammation, and immunoregulation. e main pleural pathologies are infections (tuberculosis [TB], other bacterial, and viral infections), brosis (adhesions, loculations, and pleural plaques), and cancers (e.g., mesothelioma). is chapter summarizes our present knowledge on the biology of mesothelial cells, focusing on immune regulation in the pleura and highlighting key cytokines that drive inammatory and immune responses.

This chapter describes the morphology and structure of the mesothelium and discusses some of the many roles mesothelial cells play under normal and pathological conditions. Mesothelial cells form a monolayer of cobblestone-like cells that line the peritoneal, pleural, and pericardial cavities and most internal organs. Under normal conditions, mesothelial cells form a monolayer, and play important roles in maintaining normal serosal membrane integrity and function. Mesothelial cells are unique in that they function as an epithelium but express both epithelial and mesenchymal markers and have an inherent ability to undergo Epithelial to mesenchymal transition (EMT), a process that has recently been termed mesothelial to mesenchymal transition (MMT). MMT is proposed to play a role in the establishment of endometriosis where retrograde menstrual tissue embeds on the peritoneal surface and forms an active lesion. The processes that occur during pathological EMT are thought to be comparable to physiological EMT as they are controlled by similar signaling pathway regulators and effector molecules.