Specialized pro-resolving lipid mediators protect epithelial barrier integrity of airway epithelial cells subject to a mechanical or fungal lesion - 17/02/23

Inflammation is normally self-regulated by an active resolution phase, orchestrated by specialized pro-resolving mediators (SPMs) such as lipoxins (LX), resolvins (Rv) and protectins (PD). We recently showed that SPMs biosynthesis by airway epithelial cells is altered in cystic fibrosis (CF) [1Shum M., London C.M., Briottet M., et al. CF patients’ airway epithelium and sex contribute to biosynthesis defects of pro-resolving lipids Front Immunol 2022 ;  13 : 915261

Cliquez ici pour aller à la section Références]. Among the actors that can modify the epithelial integrity, Aspergillus fumigatus (Af), a predominant filamentous fungus in cystic fibrosis (CF) and immunodeficient patients, is associated with lung injury and function decline. The aim of this study was to explore whether these SPMs have an impact on epithelial cell barrier function during mechanical lesion and Af exposure.

Airway epithelial cells (CFBE41o- cell line and human nasal epithelial cell primary cultures) were cultured either on plastic or on permeable filters under air-liquid interface (ALI) to obtain a differentiated epithelium. Af conidia were inoculated at an MOI of 1:6 on the apical side of airway epithelia simultaneously with SPMs treatment (10nM) in the basal side. Cell proliferation and repair was evaluated using the Incucyte technology (a real time live cell image analysis device). Cells barrier integrity was assessed using Trans Epithelial Electrical Resistance (TEER) measurement and by confocal immunofluorescence microscopy of tight junction protein (ZO-1) of epithelial cells. Af growth was evaluated by confocal microscopy analysis of Af-DsRed and using a Tecan® microplate reader.

SPMs (lipoxins, E-resolvins, D-resolvins, protectins) treatment significantly stimulated airway epithelial cell proliferation and enhanced TEER increase during cell differentiation. SPMs treatments also stimulated airway epithelial repair after a mechanical lesion. Although Af fungal growth was reduced in the presence of differentiated airway epithelial cells compared with undifferentiated cells, the undifferentiated cells exposed to Af showed strong cellular shape damages and significantly altered tight junctions allowing Af to transmigrate to the basolateral compartment of the cell culture insert within 24h. In contrast, SPMs treatment at the same time as Af inoculation prevented ZO-1 disruption and reduced Af growth and invasion within the epithelium. However, SPMs alone (without epithelial cells) did not directly affect Af growth.

Taken together, our data provide evidence for a role of SPM in stimulating of airway epithelial repair after mechanical injury and fighting Af invasion of airway epithelial cells by regulating Af growth, preventing epithelial damage and tight junction disruption. These data are consistent with a role for abnormal SPM biosynthesis in the reduced ability of CF airway to fight infection and have the potential to open new therapeutic perspectives [2patent # EP22305824.91.

Cliquez ici pour aller à la section Références].