Interferon regulatory factor 8 regulates expression of acid ceramidase and infection susceptibility in cystic fibrosis

• Published in: The Journal of biological chemistry Vol. 296; p. 100650
• Main Authors: Gardner, Aaron Ions, Wu, Yuqing, Verhaegh, Rabea, Liu, Yongjie, Wilker, Barbara, Soddemann, Matthias, Keitsch, Simone, Edwards, Michael J., Haq, Iram J., Kamler, Markus, Becker, Katrin Anne, Brodlie, Malcolm, Gulbins, Erich
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.01.2021; American Society for Biochemistry and Molecular Biology
• Subjects: acid ceramidase; Acid Ceramidase - genetics; Acid Ceramidase - metabolism; Animals; ceramide; Ceramides - metabolism; cystic fibrosis; Cystic Fibrosis - immunology; Cystic Fibrosis - metabolism; Cystic Fibrosis - microbiology; Cystic Fibrosis - pathology; Cystic Fibrosis Transmembrane Conductance Regulator - genetics; Cystic Fibrosis Transmembrane Conductance Regulator - metabolism; Epithelial Cells - immunology; Epithelial Cells - metabolism; Epithelial Cells - microbiology; Epithelial Cells - pathology; Humans; Interferon Regulatory Factors - genetics; Interferon Regulatory Factors - metabolism; interferon response factor-8; Lung - immunology; Lung - metabolism; Lung - microbiology; Lung - pathology; Mice; Mice, Knockout; Pseudomonas aeruginosa; Pseudomonas aeruginosa - isolation & purification; Pseudomonas Infections - genetics; Pseudomonas Infections - metabolism; Pseudomonas Infections - microbiology; sphingosine; Sphingosine - metabolism; DTPA; CF; TBS; FABP; PFA; TLC; sphingosine; SDS-PAGE; ceramide; interferon response factor-8; cystic fibrosis; FCS; Pseudomonas aeruginosa; IRF8; CFTR; acid ceramidase
• DOI: 10.1016/j.jbc.2021.100650
• ISSN: 0021-9258

Most patients with cystic fibrosis (CF) suffer from acute and chronic pulmonary infections with bacterial pathogens, which often determine their life quality and expectancy. Previous studies have demonstrated a downregulation of the acid ceramidase in CF epithelial cells resulting in an increase of ceramide and a decrease of sphingosine. Sphingosine kills many bacterial pathogens, and the downregulation of sphingosine seems to determine the infection susceptibility of cystic fibrosis mice and patients. It is presently unknown how deficiency of the cystic fibrosis transmembrane conductance regulator (CFTR) connects to a marked downregulation of the acid ceramidase in human and murine CF epithelial cells. Here, we employed quantitative PCR, western blot analysis, and enzyme activity measurements to study the role of IRF8 for acid ceramidase regulation. We report that genetic deficiency or functional inhibition of CFTR/Cftr results in an upregulation of interferon regulatory factor 8 (IRF8) and a concomitant downregulation of acid ceramidase expression with CF and an increase of ceramide and a reduction of sphingosine levels in tracheal and bronchial epithelial cells from both human individuals or mice. CRISPR/Cas9- or siRNA-mediated downregulation of IRF8 prevented changes of acid ceramidase, ceramide, and sphingosine in CF epithelial cells and restored resistance to Pseudomonas aeruginosa infections, which is one of the most important and common pathogens in lung infection of patients with CF. These studies indicate that CFTR deficiency causes a downregulation of acid ceramidase via upregulation of IRF8, which is a central pathway to control infection susceptibility of CF cells.