Infection and Drug Resistance (Apr 2023)
Decreased Sphingosine Due to Down-Regulation of Acid Ceramidase Expression in Airway of Bronchiectasis Patients: A Potential Contributor to Pseudomonas aeruginosa Infection
Abstract
Qian Qi,1,2,* Jiawei Xu,1,2,* Yujiao Wang,3,* Jian Zhang,1 Mingxia Gao,1 Yu Li,4 Liang Dong1,2 1Department of Respiratory, the First Affiliated Hospital of Shandong First Medical University & Shandong Provincial Qianfoshan Hospital, Shandong Institute of Respiratory Diseases, Jinan, Shandong Province, People’s Republic of China; 2Department of Respiratory, Shandong Provincial Qianfoshan Hospital, Shandong University, Jinan, Shandong Province, People’s Republic of China; 3Department of Clinical Laboratory Medicine, the First Affiliated Hospital of Shandong First Medical University & Shandong Provincial Qianfoshan Hospital, Jinan, Shandong Province, People’s Republic of China; 4Department of Respiratory, Qilu Hospital, Shandong University, Jinan, Shandong Province, People’s Republic of China*These authors contributed equally to this workCorrespondence: Liang Dong, Department of Respiratory, the First Affiliated Hospital of Shandong First Medical University & Shandong Provincial Qianfoshan Hospital, #16766, Jingshi Road, Jinan, Shandong Province, 250014, People’s Republic of China, Tel +86 13505401207, Email [email protected]: To assess the metabolites associated with Pseudomonas aeruginosa infection by analyzing the microbial diversity and metabolomics in lower respiratory tract of bronchiectasis patients and to explore the therapeutic approaches for Pseudomonas aeruginosa infection.Methods: Bronchoalveolar lavage fluid samples from bronchiectasis patients and controls were analyzed by 16S rRNA and ITS sequencing, and metabolomic analysis was performed by liquid chromatography/mass spectrometry. A co-culture model of air-liquid interface cultured human bronchial epithelial cell with Pseudomonas aeruginosa was constructed to verify the correlation between sphingosine metabolism, acid ceramidase expression, and Pseudomonas aeruginosa infection.Results: After screening, 54 bronchiectasis patients and 12 healthy controls were included. Sphingosine levels in bronchoalveolar lavage fluid were positively correlated with lower respiratory tract microbial diversity and negatively correlated with the abundance of Pseudomonas spp. Moreover, sphingosine levels in bronchoalveolar lavage fluid and acid ceramidase expression levels in lung tissue specimens were significantly lower in bronchiectasis patients than in healthy controls. Sphingosine levels and acid ceramidase expression levels were also significantly lower in bronchiectasis patients with positive Pseudomonas aeruginosa cultures than in bronchiectasis patients without Pseudomonas aeruginosa infection. Acid ceramidase expression in air-liquid interface cultured human bronchial epithelial cell had significantly increased after 6 h of Pseudomonas aeruginosa infection, while it had decreased significantly after 24 h of infection. In vitro experiments showed that sphingosine had a bactericidal effect on Pseudomonas aeruginosa by directly disrupting its cell wall and cell membrane. Furthermore, adherence of Pseudomonas aeruginosa on bronchial epithelial cells was significantly reduced after sphingosine supplementation.Conclusion: Down-regulation of acid ceramidase expression in airway epithelial cells of bronchiectasis patients leads to insufficient metabolism of sphingosine, which has a bactericidal effect, and consequently weakens the clearance of Pseudomonas aeruginosa; thus, a vicious circle is formed. Exogenous supplementation with sphingosine aids bronchial epithelial cells in resisting Pseudomonas aeruginosa infection.Keywords: metabolomics, bronchiectasis, sphingosine, Pseudomonas aeruginosa, acid ceramidase
