Cliff Taggart

Keratinocyte Growth Factor Promotes Epithelial Survival and Resolution in a Human Model of Lung Injury

RATIONALE Increasing epithelial repair and regeneration may hasten resolution of lung injury in patients with the acute respiratory distress syndrome (ARDS). In animal models of ARDS, keratinocyte growth factor (KGF) reduces injury and increases epithelial proliferation and repair. The effect of KGF in the human alveolus is unknown. OBJECTIVES To test whether KGF can attenuate alveolar injury in a human model of ARDS. METHODS Volunteers were randomized to intravenous KGF (60 μg/kg) or placebo for 3 days, before inhaling 50 μg LPS. Six hours later, subjects underwent bronchoalveolar lavage (BAL) to quantify markers of alveolar inflammation and cell-specific injury. MEASUREMENTS AND MAIN RESULTS KGF did not alter leukocyte infiltration or markers of permeability in response to LPS. KGF increased BAL concentrations of surfactant protein D, matrix metalloproteinase (MMP)-9, IL-1Ra, granulocyte-macrophage colony-stimulating factor (GM-CSF), and C-reactive protein. In vitro, BAL fluid from KGF-treated subjects inhibited pulmonary fibroblast proliferation, but increased alveolar epithelial proliferation. Active MMP-9 increased alveolar epithelial wound repair. Finally, BAL from the KGF-pretreated group enhanced macrophage phagocytic uptake of apoptotic epithelial cells and bacteria compared with BAL from the placebo-treated group. This effect was blocked by inhibiting activation of the GM-CSF receptor. CONCLUSIONS KGF treatment increases BAL surfactant protein D, a marker of type II alveolar epithelial cell proliferation in a human model of acute lung injury. Additionally, KGF increases alveolar concentrations of the antiinflammatory cytokine IL-1Ra, and mediators that drive epithelial repair (MMP-9) and enhance macrophage clearance of dead cells and bacteria (GM-CSF). Clinical trial registered with ISRCTN 98813895.

The parasitic 68-mer peptide FhHDM-1 inhibits mixed granulocytic inflammation and airway hyperreactivity in experimental asthma

Tanaka, A., Allam, V., Simpson, J., Tiberti, N., Shiels, J., To, J., Lund, M., Combes, V., Weldon, S., Taggart, C., Dalton, J., Phipps, S., Sukkar, M., & Donnelly, S. (2018). The Parasitic 68-mer Peptide FhHDM-1 inhibits mixed granulocytic inflammation and airway hyperreactivity in experimental asthma. Journal of Allergy and Clinical Immunology, 141(6), 2316-2319. https://doi.org/10.1016/j.jaci.2018.01.050

A role for cathepsin S in the pathogenesis of cystic fibrosis lung disease

The pathogenesis of lung disease in cystic fibrosis (CF) has not been fully elucidated, however, neutrophil-dominated inflammation is thought to play a major role. Nonetheless, a number of proteases produced by other cells in the lung may play a pivotal role in CF lung damage. Human lysosomal cysteine proteases are a family of proteases that have been relatively unexplored in the area of CF lung disease. We have shown that cathepsin S activity is increased in CF bronchoalveolar lavage fluid. In addition to lung tissue degradation, cathepsins have been found to contribute significantly to the destruction of host defence proteins such as SLPI, β-defensins and lactoferrin. These findings indicate a role for cathepsin S in the diminution of the lung antiprotease and antimicrobial screen possibly leading to lung destruction and favouring conditions for bacterial infection. We have identified epithelial cells as a source of cathepsin S in the CF lung with the demonstration that CF bronchial and tracheal epithelial cell lines express and secrete significantly more active cathepsin S than normal cells in the absence of proinflammatory stimulation. These findings were confirmed in primary human bronchial epithelial cells from CF patients. On the basis of our results to date, we postulate that upregulated cathepsin S plays an important role in CF lung disease and we are currently investigating reasons for this upregulation of cathepsin S in CF epithelial cells. This data will shed valuable light on the role of cathepsin S in CF, an area that has been overshadowed to date, and may open up new avenues for exploration in the search for an effective therapeutic target in CF lung disease.

29 Airway epithelial cell IP-10 production is regulated by miR-31 via the transcription factor IRF-1

The C-X-C motif chemokine 10 (CXCL10) or interferon gamma-induced protein 10 (IP-10) is a pro-inflammatory cytokine which has been attributed to many roles including cellular activation and migration. The activity of this cytokine is mediated by binding to the CXCR3 receptor primarily on T cells, natural killer cells, macrophages and also neutrophils. IP-10 is produced by a wide variety of inflammatory cells and also airway epithelia. Previous work has shown that increased levels of IP-10 are present in bronchoalveolar lavage fluid from patients with CF. In this study, we evaluated IP-10 levels in CF pulmonary epithelial cells and found that IP-10 expression and production were significantly increased in CF tracheal and bronchial epithelial cell lines compared to non-CF controls. The transcription factor IRF-1 has been reported to play a role in the regulation of IP-10 and our recent work has shown that IRF-1 levels are increased in CF pulmonary epithelial cells via dysregulation of the miRNA, miR-31. In agreement with previous work, knockdown of IRF-1 using siRNA significantly decreased expression and secretion of IP-10 from CF bronchial epithelial cells. In addition, overexpression of miR-31 in CF bronchial epithelial cells resulted in a decrease in the levels of IRF-1, which was also associated with a significant decrease in the expression and production of IP-10. These findings suggest that pulmonary epithelial cells may be a potential source of IP-10 in the CF lung via dysregulated miR-31. Further work is required to elucidate the role of elevated IP-10 in the pathogenesis of CF lung disease.

165 An immunomodulatory role for the serine protease inhibitor, eppin, in the lung

A. Glasgow1, A. Scott1, M. McCrudden1, D. McLean1, F. Lundy1, C. Irwin2, D. Timson3, M. Tunney4, J.S. Elborn1, S. Weldon1, C. Taggart1. 1Queen’s University Belfast, Centre for Infection and Immunity, Belfast, United Kingdom; 2Queen’s University Belfast, Centre for Dental Education, Belfast, United Kingdom; 3Queen’s University Belfast, School of Biological Sciences, Belfast, United Kingdom; 4Queen’s University Belfast, School of Pharmacy, Belfast, United Kingdom

150 CF epithelial cells are primed for apoptosis as a result of increased Fas

Apoptosis is a physiological process essential for homeostasis of epithelial organisation and function. CF lung disease is characterised by chronic infection and inflammation and previous work suggests that apoptosis is dysfunctional in the CF airways with conflicting results. In addition, controversy exists regarding how CFTR misfolding contributes to apoptosis. In this study, we evaluated the relationship between CFTR mutation and apoptosis in DF508-CFTR CF airway epithelial cells. Basal activity of the executioner caspase, caspase-3, was significantly increased in CF tracheal and bronchial epithelial cell lines and primary bronchial epithelial cells compared to non-CF controls. In addition, activity of the upstream initiator caspase, caspase-8, was significantly increased in CF epithelial cells compared to controls, suggesting involvement of extrinsic apoptosis signalling, which is mediated by the activation of death receptors, such as Fas (CD95). Increased levels of Fas were observed in CF epithelial cells, and neutralization of Fas significantly inhibited caspase-3 activity in CF epithelial cells compared to untreated cells. Furthermore, activation of Fas significantly increased caspase-3 activity and apoptosis in CF epithelial cells compared to control cells. Overall, these results suggest that CF airway epithelial cells are more sensitive to apoptosis via increased levels of Fas and subsequent activation of the Fas death receptor pathway.