Mesothelial CXCL10 potentiates fibre-driven inflammation within the pleural cavity

Basílio Queijo, Ivo and Jackson-Jones, Lucy (2025) Mesothelial CXCL10 potentiates fibre-driven inflammation within the pleural cavity. Masters thesis, Lancaster University.

Text (2025IvoBasilioQueijoMScbyResearch)
2025IvoBasilioQueijoMScbyResearch.pdf - Published Version
Restricted to Repository staff only until 12 June 2030.
Available under License Creative Commons Attribution-NonCommercial-NoDerivs.
Download (4MB)

Abstract

The pleural cavity is the potential closed space between the two pleurae in the thoracic cavity, which line the lungs and the inner walls of the thoracic cage. The pleurae are composed of mesothelial cells which can be affected by certain medical conditions, like malignant pleural mesothelioma (MPM). MPM refers to the devastating neoplasm of the mesothelial cells of the pleural cavity, linked to asbestos exposure. Clinical signs of mesothelioma develop around 4 decades after asbestos exposure, so it affects primarily older individuals. Protein CXCL10 has been linked to mesothelioma and has been found to be increased in this condition. The aim of this study was, therefore, to truly understand how CXCL10 plays a role in fibre-induced inflammation of the pleural cavity. To induce inflammation and recreate this environment, we used asbestos-like fibres NM-401 multiwalled carbon nanotubes (MWCNTs/CNTs). CNTs are structurally similar to asbestos and share the same bio-persistent profile, which confers them their carcinogenic properties. To investigate CXCL10 importance in this context, we firstly deliver by intra-pleural (i.pl) injection a lentiviral construct expressing CRE recombinase under the control of the mesothelin promoter to target deletion of the Cxcl10 gene exclusively to mesothelial cells of Cxcl10fl/fl mice. Mice were then instilled with the CNT and pleural lavage and adipose tissues were collected 4 or 14 days after CNT delivery. Immune cell identification was performed via flow cytometry, adipose tissue was also analysed through confocal microscopy, and cytokine and chemokine expression analysed with multi-plex assay. We firstly confirmed that age impairs immune responses and alters secretion of soluble mediators. We then moved on and ascertained differences in the pleural cavity inflammation with CNT instillation. Delivery of these resulted in increased infiltration of cells like neutrophils, monocytes and small cavity macrophages (SCM) to the pleural fluid. Deletion of the Cxcl10 gene then led to a decrease in the recruitment of these cells to the pleural fluid and monocyte recruitment to the Fat-Associated Lymphoid Clusters (FALCs), thus proposing a reduction in inflammation four days after CNT instillation. Interestingly, IFN-γ was not detected in our assays. Other soluble mediators such as TNFα, CCL4, IL-4, and IL-10 were all increased with CNT instillation, but not changed with Cxcl10 deletion, at day 4. At 14 days, we observed a similar trend in the recruitment of immune cells to the pleural fluid, though the number of cells was reduced compared to day 4. Recruitment of neutrophils, monocytes and SCM was negatively impacted with blockage of CXCL10 production from mesothelial cells, and observed an accumulation of monocytes in the FALCs away from the pleural fluid. We confirmed reduction of CXCL10 with our construct and observed an increase in secretion of certain cytokines such as IL-4, IL-6 and more importantly, IL-10. We proposed that IL-10 is a possible mechanism by which blocking mesothelial cells from producing CXCL10 induces a faster resolution of the pleural cavity inflammation in a fibre-driven context.