Mesothelial Cells in Fibrosis: Focus on Intercellular Crosstalk.

Mesothelial cells line serosal cavities and internal organs, playing a vital role in maintaining serosal integrity and homeostasis. Their remarkable plasticity and ability to undergo mesothelial-to-mesenchymal transition (MMT) position them as key regulators of tissue repair. However, when normal repair processes fail, mesothelial cells can acquire a profibrotic phenotype. They actively contribute to all stages of fibrosis development, including inflammation, fibrin accumulation, myofibroblast differentiation, and extracellular matrix (ECM) remodeling. Fibrotic progression involves multiple cell types, and communication among them is essential for its perpetuation. Mesothelial cells are implicated in bidirectional crosstalk with fibroblasts, macrophages, lymphocytes, and endothelial cells of the serosal microenvironment through direct contact, paracrine signaling, and extracellular vesicle exchange. These interactions regulate immune cell recruitment, cytokine balance, endothelial permeability, and ECM deposition, while, in turn, immune and endothelial cells modulate mesothelial activation, proliferation, and transition. Understanding this complex network of intercellular communication provides new insights into fibrosis pathogenesis and reveals promising targets for antifibrotic therapies.