[Effect of different fat emulsions on acute lung injury induced by endotoxin].

Objective: To assess the effect of Clinoleic 20% (olive oil-based, n-9) and Lipoven 20% (soy bean-based, n-6) lipid emulsions on inflammatory parameters in a murine acute lung injury (ALI) model induced by lipopolysaccharide (LPS) of E. coli O111:B4.

Methods: Male Balb/C mice were infused for three days with 0.9% NaCl, Clinoleic 20%, or Lipoven 20% respectively, and sacrificed either at 8 hours or 24 hours after intra-tracheal introduction of LPS. Survival rate, lung wet/dry weight ratio (W/D), lung tissue myeloperoxidase (MPO) activity were determined, and tumor necrosis factor-alpha (TNF-alpha) and macrophage inflammatory protein-2 (MIP-2) in bronchoalveolar lavage fluid (BALF) were determined with enzyme linked immunosorbent assay (ELISA). Serum free fatty acids [arachidonic acid (AA), oleic acid, linoleic acid] were determined by gas chromatography. Leukocytes in BALF were counted under light microscope.

Results: Lipoven significantly decreased survival rate at 24 hours after intra-tracheal LPS challenge compared to corresponding controls (both P<0.01). No significant difference was observed between Clinoleic and NaCl groups. MPO activity was obviously increased in lipids groups than that in NaCl group at 24 hours (both P<0.01), and no difference was found between two lipids groups. LPS markedly induced an increase in leukocyte infiltration, W/D ratio, lung MPO activity, release of TNF-alpha as well as MIP-2 into alveolar space in both lipids and NaCl groups. Pre-infusion with Lipoven gave rise to heavier leukocyte infiltration at 24 hours, which was blunted in Clinoleic group and NaCl group (both P<0.01). In contrast to Clinoleic and NaCl groups, Lipoven increased production of TNF-alpha at 24 hours and MIP-2 at 8 hours in LPS-treated mice (all P<0.01). Notably, lipid emulsions increased LPS-induced MPO activity, but no difference in effects was found in both Lipoven and Clinoleic groups. Clinoleic significantly reduced free AA at 8 and 24 hours compared with Lipoven (both P<0.01). There were no differences in lung tissues edema, serum oleic acid and linoleic acid among three groups.

Conclusion: In murine model of ALI, although LPS caused an increase in alveolar leucocytic infiltration, MPO activity, cytokine generation in both lipids and NaCl groups, Lipoven 20%, n-6 lipid emulsion induces a severer inflammatory reaction. It is speculated that by increasing AA, Lipoven 20% may aggravate ALI, whereas Clinoleic 20%, n-9 lipid emulsion possibly offers an alternative choice in producing less impact on inflammatory lung injury.