839.11 - Acat-1 Inhibition Reduces Inflammatory Response to Bleomycin-mediated Lung Injury

Tuesday, April 5, 2022

10:30 AM – 10:33 AM

Room: ASPET Poster Discussion Area, Exhibit Hall Booth #1418 - Pennsylvania Convention Center

Introduction: Experience the daily ASPET datablitz, a rapid-fire oral presentation of research. Ten poster presenters each day will present three minute short talks in the ASPET poster discussion lounge in the poster hall (Aisle 1400). These brief snippets of research are an introduction to their full presentations that will take place at their poster boards afterwards. You won’t want to miss this fast-paced overview of the most exciting science of the day.

Emily Stevenson (Rutgers, The State University of New Jersey), Melissa Wilkinson (Rutgers, The State University of New Jersey), Elena Abramova (Rutgers, The State University of New Jersey), Chiangjiang Guo (Rutgers, The State University of New Jersey), Andrew Gow (Rutgers, The State University of New Jersey)

Presenting Author(s)

Emily Stevenson

Presenting Author
Rutgers, The State University of New Jersey

Acute lung injury (ALI) is characterized by epithelial damage, barrier dysfunction, and pulmonary edema. Macrophage (MΦ) activation and failure to resolve play a role in in ALI, thus MΦ phenotype modulation is a rational target for therapeutic intervention. Large, lipid-laden MΦs have been observed in various injury models, including intratracheal bleomycin (ITB), suggesting that lipid storage may play a role in ALI severity. The mitochondrial enzyme Acat-1 is highly expressed in MΦs where it catalyzes the esterification of cholesterol, leading to intracellular lipid accumulation. We hypothesize that inhibition of Acat-1 will reduce MΦ activation and reduce ITB-mediated lung injury. K-604, a selective inhibitor of Acat-1, was used to reduce lipid accumulation in ITB. Male and female C57BL6/J mice (n=16-21/group) were administered PBS, K-604, ITB, or ITB +K-604 on d0, PBS or K-604 on d3, and were sacrificed on d7. ITB caused significant (*plt;0.05 v PBS) body weight loss (-13.92±2.05%* v 2.66±0.78%) and an increase in cholesterol accumulation (71.63±11.7 μM* v 15.51±9.1 μM) and size (29.67±10.6 μm* v 11±4.3 μm) of pulmonary MΦs. These changes were mitigated by Acat-1 inhibition, as ITB+K-604 mice had significantly (#plt;0.05 v ITB) reduced body weight loss (4.04±1.03%#), cholesterol accumulation (13.79±5.4#), and MΦ diameter (14.0±3.7 μm#), confirming successful inhibition of Acat-1 in the lung. Histological analysis showed that K-604 significantly reduced ITB-induced alveolar wall thickening (2.3±0.05 μm# v 4.35±0.04 μm) and reduced measures of consolidation and cell infiltration. Surface active function was normalized as indicated by a significant decrease in phospholipid:SP-B ratio in ITB+K-604 compared to ITB (7.95±1.22# v 13.28±2.17). K-604 administration rescued ITB-mediated loss of resident alveolar MΦs (CD45+/Siglec F+/F/480+, CD11c+, CD11b-) (72.00±5.67%# v 49.58±8.52%) and was found to decrease the % of pro-inflammatory alveolar MΦs (CD45+/Siglec F+/F/480+, Ly6c+, CD206-) (3.86±0.88%# v 8.22±1.76%). K-604 reduced ITB-mediated increases in NOS2 (64.23±20.07# v 131.89±17.07) and ARG1 expression (42.39±8.14# v 177.41±52.2) in BAL MΦs, suggesting reduced inflammatory signaling and immunometabolic demand. In our ITB model, K-604 also decreased the % of interstitial MΦs (IMs) (tissue-derived CD45+, Siglec F -, F4/80+, CD11b+) expressing markers of maturity and fibrotic potential (CD11c+/CD206+) (5.89±2.15%# v 19.72±1.93%). IMs were also found to have an increased rate of lipid uptake after K-604 regardless of ITB administration as measured by the uptake of fluorescently labeled LDL and visualization by confocal microscopy. These data, along with changes in cholesterol ester accumulation, suggest that Acat-1 inhibition alters lipid storage and uptake within pulmonary macrophages, affecting cell phenotype and function. Thus, Acat-1 may be a target for intervention in ALI.

Supported by NIH HL086621 and 4T32ES007148-30.