Fatty acid nitroalkenes inhibit the inflammatory response to bleomycin-mediated lung injury

Melissa L. Wilkinson, Elena Abramova, Changjiang Guo, James G. Gow, Alexa Murray, Adolf Koudelka, Veronika Cechova, Bruce A. Freeman, Andrew J. Gow

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Fatty acid nitroalkenes are reversibly-reactive electrophiles, endogenously detectable at nM concentrations, displaying anti-inflammatory actions. Nitroalkenes like 9- or 10-nitro-octadec-9-enoic acid (e.g. nitro-oleic acid, OA-NO2) pleiotropically suppress cardiovascular inflammatory responses, with pulmonary responses less well defined. C57BL/6 J male mice were intratracheally administered bleomycin (3 U/kg, ITB), to induce pulmonary inflammation and acute injury, or saline and were treated with 50 μL OA-NO2 (50 μg) or vehicle in the same instillation and 72 h post-exposure to assess anti-inflammatory properties. Bronchoalveolar lavage (BAL) and lung tissue were collected 7d later. ITB mice lost body weight, with OA-NO2 mitigating this loss (−2.3 ± 0.94 vs −0.4 ± 0.83 g). Histology revealed ITB induced cellular infiltration, proteinaceous debris deposition, and tissue injury, all significantly reduced by OA-NO2. Flow cytometry analysis of BAL demonstrated loss of Siglec F+/F4/80+/CD45+ alveolar macrophages with ITB (89 ± 3.5 vs 30 ± 3.7%). Analysis of CD11b/CD11c expressing cells showed ITB-induced non-resident macrophage infiltration (4 ± 2.3 vs 43 ± 2.4%) was decreased by OA-NO2 (24 ± 2.4%). Additionally, OA-NO2 attenuated increases in mature, activated interstitial macrophages (23 ± 4.8 vs. 43 ± 5.4%) in lung tissue digests. Flow analysis of CD31/CD45/Sca-1+ mesenchymal cells revealed ITB increased CD44+ populations (1 ± 0.4 vs 4 ± 0.4MFI), significantly reduced by OA-NO2 (3 ± 0.4MFI). Single cell analysis of mesenchymal cells by western blotting showed profibrotic ZEB1 protein expression induced by ITB. Lung digest CD45+ cells revealed ITB increased HMGB1+ cells, with OA-NO2 suppressing this response. Inhibition of HMGB1 expression correlated with increased basal phospholipid production and SP-B expression in the lung lining. These findings indicate OA-NO2 inhibits ITB-induced pro-inflammatory responses by modulating resident cell function.

Original languageEnglish (US)
Article number115236
JournalToxicology and applied pharmacology
StatePublished - Nov 15 2020

All Science Journal Classification (ASJC) codes

  • Toxicology
  • Pharmacology


  • Acute Lung Injury
  • Bleomycin
  • Inflammation
  • Macrophage
  • Nitro-Oleic Acid
  • Nitroalkene

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    Wilkinson, M. L., Abramova, E., Guo, C., Gow, J. G., Murray, A., Koudelka, A., Cechova, V., Freeman, B. A., & Gow, A. J. (2020). Fatty acid nitroalkenes inhibit the inflammatory response to bleomycin-mediated lung injury. Toxicology and applied pharmacology, 407, [115236]. https://doi.org/10.1016/j.taap.2020.115236