Acetylated Diacylglycerol 1-palmitoyl-2-linoleoyl-3-acetyl-rac-glycerol in Autoimmune Arthritis and Interstitial Lung Disease in SKG Mice

Acetylated diacylglycerol 1-palmitoyl-2-linoleoyl-3-acetyl-rac-glycerol (PLAG) is a lipid molecule from the antlers of sika deer that might reduce inflammation by effectively controlling neutrophil infiltration, endothelial permeability and inflammatory chemokine production. Therefore, we evaluated the modulatory effect of PLAG on arthritis and interstitial lung disease (ILD) in an autoimmune arthritis model. We injected curdlan into SKG mice and PLAG was orally administered every day from 3 weeks to 20 weeks after the curdlan injection. The arthritis score was measured every week after the curdlan injection. At 20 weeks post-injection, the lung specimens were evaluated with H&E, Masson's trichrome and multiplexed immunofluorescent staining. Serum cytokines were also analyzed using a Luminex multiple cytokine assay. PLAG administration decreased the arthritis score until 8 weeks after the curdlan injection. However, the effect was not sustained thereafter. A lung histology revealed severe inflammation and fibrosis in the curdlan-induced SKG mice, which was attenuated in the PLAG-treated mice. Furthermore, immunofluorescent staining of the lung tissue showed a GM-CSF neutrophil accumulation and a decreased citrullinated histone 3 expression after PLAG treatment. PLAG also downregulated the levels of IL-6 and TNF-α and upregulated the level of sIL-7Rα, an anti-fibrotic molecule. Our results indicate that PLAG might have a preventative effect on ILD development through the resolution of NETosis in the lung.