I-Fang Tsai1, Chiu-Ping Kuo2, Andrew B Lin3, Ming-Nan Chien4, Hsin-Tsung Ho5,6, Tsai-Yin Wei1, Chien-Liang Wu2,7, Yen-Ta Lu2,6. 1. Department of Medical Research, MacKay Memorial Hospital, Taipei, Taiwan. 2. Division of Chest Medicine, Department of Internal Medicine, MacKay Memorial Hospital, Taipei, Taiwan. 3. Biology Department, Case Western Reserve University, Cleveland, Ohio, USA. 4. Department of Endocrinology and Metabolism, MacKay Memorial Hospital, Taipei, Taiwan. 5. Department of Laboratory Medicine, MacKay Memorial Hospital, Taipei, Taiwan. 6. Department of Medicine, MacKay Medical College, New Taipei City, Taiwan. 7. MacKay Junior College of Medicine, Nursing, and Management, Taipei, Taiwan.
Abstract
BACKGROUND AND OBJECTIVE: Tuberculosis (TB) risk might be increased in patients with diabetes by factors other than hyperglycaemia, such as dyslipidaemia. Host lipids are essential energy sources used by mycobacteria to persist in a latent TB state. A potential therapy targeting cholesterol catabolism of mycobacteria has been proposed, but the potential of cholesterol-lowering drugs as anti-TB therapy is unclear. The purpose of this study was to determine the effects of ezetimibe, a 2-azetidinone cholesterol absorption inhibitor, on intracellular mycobacteria survival and dormancy. METHODS: Intracellular mycobacteria survival was determined by measurements of ATP activity and colony-formation units (CFUs). Gene expression profiles of hypoxia-induced dormant Mycobacterium tuberculosis (Mtb) were analysed by real-time PCR. Flow cytometry and microscopy analysis were used to measure the lipid loads of human macrophages with or without ezetimibe treatment. QuantiFERON-TB Gold In-Tube (QFT-G-IT) assays were performed to diagnose latent TB infection. The levels of intracellular cholesterol/ triglyceride were measured by an enzymatic fluorometric method. RESULTS: Ezetimibe was capable of effectively lowering intracellular growth of Mtb and hypoxia-induced dormant Mtb. There was a significant decrease in Mtb growth in leucocytes from ezetimibe-treated patients with diabetes in terms of ATP levels of intracellular mycobacteria and CFU formation. Also, patients receiving ezetimibe therapy had a lower prevalence of latent TB and had lower intracellular lipid contents. CONCLUSION: Ezetimibe, which is a currently marketed drug, could hold promise as an adjunctive, host-directed therapy for TB.
BACKGROUND AND OBJECTIVE:Tuberculosis (TB) risk might be increased in patients with diabetes by factors other than hyperglycaemia, such as dyslipidaemia. Host lipids are essential energy sources used by mycobacteria to persist in a latent TB state. A potential therapy targeting cholesterol catabolism of mycobacteria has been proposed, but the potential of cholesterol-lowering drugs as anti-TB therapy is unclear. The purpose of this study was to determine the effects of ezetimibe, a 2-azetidinone cholesterol absorption inhibitor, on intracellular mycobacteria survival and dormancy. METHODS: Intracellular mycobacteria survival was determined by measurements of ATP activity and colony-formation units (CFUs). Gene expression profiles of hypoxia-induced dormant Mycobacterium tuberculosis (Mtb) were analysed by real-time PCR. Flow cytometry and microscopy analysis were used to measure the lipid loads of human macrophages with or without ezetimibe treatment. QuantiFERON-TB Gold In-Tube (QFT-G-IT) assays were performed to diagnose latent TB infection. The levels of intracellular cholesterol/ triglyceride were measured by an enzymatic fluorometric method. RESULTS:Ezetimibe was capable of effectively lowering intracellular growth of Mtb and hypoxia-induced dormant Mtb. There was a significant decrease in Mtb growth in leucocytes from ezetimibe-treated patients with diabetes in terms of ATP levels of intracellular mycobacteria and CFU formation. Also, patients receiving ezetimibe therapy had a lower prevalence of latent TB and had lower intracellular lipid contents. CONCLUSION:Ezetimibe, which is a currently marketed drug, could hold promise as an adjunctive, host-directed therapy for TB.