Effect of CCL2 antisense oligodeoxynucleotides on bacterial translocation and subsequent sepsis in severely burned mice orally infected with Enterococcus faecalis

Severely burned mice are susceptible to sepsis stemming from Enterococcus faecalis translocation due to the impaired generation of M1 macrophages (M1Mφ{symbol}s) in local translocation sites. In our previous studies, CCL2 has been characterized as a major effector molecule on the burn-associated generation of M2Mφ{symbol}s, an inhibitor cell type for resident Mφ{symbol} conversion into M1Mφ{symbol}s. In this study, we tried to protect burned mice orally infected with E. faecalis utilizing CCL2 antisense oligodeoxynucleotides (ODNs). We show that M2Mφ{symbol}s in mesenteric lymph nodes (MLNs) were not demonstrated in burned mice treated with CCL2 antisense ODNs. M1Mφ{symbol}s were not induced by heat-killed E. faecalis from resident Mφ{symbol}s transwell-cultured with mesenteric lymph node macrophages (MLN-Mφ{symbol}s) from burned mice, while M1Mφ{symbol}s were induced by the same antigen from resident Mφ{symbol}s transwell-cultured with Mφ{symbol}s which were isolated from burned mice treated with CCL2 antisense ODNs. Bacterial growth in MLNs was shown in burned mice orally infected with a lethal dose of E. faecalis. However, after the same infection, sepsis did not develop in burned mice treated with CCL2 antisense ODNs. These results indicate that bacterial translocation and subsequent sepsis are controlled in burned mice orally infected with a lethal dose of E. faecalis by gene therapy utilizing CCL2 antisense ODNs.