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A2965 - Inhibition of Glutamine Metabolism Accelerates Resolution of Acute Lung Injury
Author Block: C. Vigeland1, H. S. Beggs1, S. Collins2, J. Powell3, C. M. Doerschuk4, M. R. Horton5; 1Pulmonary and Critical Care, University of North Carolina, Chapel Hill, NC, United States, 2Pulmonary and Critical Care, Baltimore, MD, United States, 3Oncology, Sidney Kimmel Cancer Center, Baltimore, MD, United States, 4Univ of N Carolina, Chapel Hill, NC, United States, 5Johns Hopkins Univ, Baltimore, MD, United States.
RATIONALE: Despite causing significant morbidity and mortality, there are few effective therapies for ARDS. Dysregulated inflammation and repair are believed to underlie ARDS, and activated neutrophils and macrophages, reactive oxygen species, and pro-inflammatory cytokines have been implicated in this disease. Due to their high metabolic needs, these inflammatory cells rely upon increased glutamine metabolism to support activation, proliferation, and function. We hypothesize that by inhibiting glutamine metabolism, we can lessen the inflammation seen in ARDS and accelerate resolution of injury. METHODS: Acute lung injury (ALI) was induced in C57BL/6 mice by intratracheal administration of either LPS or bleomycin. The glutamine analog 6-diazo-5-oxo-L-norleucine (DON) was then administered via intraperitoneal injection. For LPS experiments, DON was administered on days 2 and 4, followed by harvest on day 5 to assess lung injury. For bleomycin experiments, DON was administered on days 7, 9, 11, and 13, followed by harvest on day 14. Bronchoalveolar lavage (BAL) fluid and lung tissue were collected and processed to assess the number and type of inflammatory cells present by flow cytometric analysis. Cytokine production in the BAL fluid and lung tissue was assessed by ELISA and RT-PCR. RESULTS: In LPS-induced ALI, mice treated with DON showed accelerated recovery of weight and a reduction in lung inflammation, with fewer neutrophils and inflammatory macrophages (CD45+Ly6G-CD64+SiglecF-Ly6C+) on day 5. The concentration of TNF-α within the BAL fluid was also lower. In bleomycin-induced ALI, DON treatment reduced mortality and resulted in less lung inflammation, with fewer neutrophils and Th17 cells than in vehicle-treated mice. Expression of the pro-fibrotic cytokine, IL-1β, was also reduced. CONCLUSIONS: Our findings indicate that inhibition of glutamine metabolism with DON reduces established lung inflammation and promotes recovery in ALI. Treatment with DON reduces lung neutrophils and inflammatory macrophages following LPS injury and reduces neutrophils and Th17 cells following bleomycin injury. These data indicates the important role of glutamine metabolism in promoting lung inflammation and reveals a new potential therapeutic target for ARDS.