Quantification of neutrophil infiltration was also determined (Fig. 2D). Interestingly, the number of neutrophils was significantly Selleckchem Adriamycin decreased in not only global TLR4−/−, but also in Alb-TLR4−/− mice. These results again demonstrate the importance of hepatocyte TLR4 in I/R inflammatory response. HMGB1 is an evolutionarily conserved protein present in the nucleus of almost all eukaryotic cells, where it functions to stabilize nucleosomes and acts as a transcription factor.18 HMGB1 is also rapidly mobilized and released in the setting of hepatic I/R to act as a key damage-associated molecular pattern (DAMP) molecule.5, 19 TLR4 and HMGB1 are intimately related, with
TLR4 both functioning as a receptor for HMGB1 in addition to mediating its nucleocytoplasmic shuttling and subsequent GSI-IX release.7, 19 Thus, we sought to determine the role of cell-specific TLR4−/− in the release of HMGB1 after hepatic I/R. When serum HMGB1 levels after
I/R were analyzed, Alb-TLR4−/− Tg mice had significantly lower serum HMGB1 levels, compared to WT (Fig. 3A). Lyz-TLR4−/− also had lower serum HMGB1 levels, but did not reach statistical significance (Fig. 3A). Alb-TLR4−/− and global TLR4−/− mice had HMGB1 levels that were similar and significantly lower than Lyz-TLR4−/− mice (Fig. 3A). On the other hand, CD11c-TLR4−/− mice did not have any significant difference in HMGB1 levels, compared to WT. Because TLR4 on HCs appeared to be the main contributor to TLR4-mediated HMGB1 release after I/R, we next further investigated HMGB1 release in Alb-TLR4−/− and global TLR4−/− mice. These mice had decreased levels of circulating HMGB1 after both 3 and 6 hours of reperfusion, when compared to WT mice (Fig. 3B). IF staining of liver sections of these mice confirmed the role that TLR4 plays in the release of HMGB1 after I/R. Both Alb-TLR4−/− and global TLR4−/− mice livers had retained nuclear and decreased
cytoplasmic HMGB1, when compared to WT mice 上海皓元 (Fig. 3C). Our findings show that TLR4, on parenchymal cells, are the main contributors to circulating HMGB1 release during liver I/R. It has been found previously that decreased expression of hepatoprotective factors HO-1 and IL-10 from KCs and decreased IL-10 from DCs resulted in increased I/R injury.20-22 Therefore, we investigated IL-10 and HO-1 expression in Lyz-TLR4−/− and CD11c-TLR4−/− mice. When compared to WT mice, Lyz-TLR4−/− mice had both IL-10 and HO-1 up-regulated after I/R, possibly leading to the protection noted in these mice (Fig. 4A,C). This expression pattern was confirmed at the protein level as well (Fig. 4B,D). Additionally, expression of IL-10 was decreased in CD11c-TLR4−/− mice after I/R, suggesting a mechanism for the increased hepatocellular injury noted in these mice (Fig. 4C,D). Alb-TLR4−/− did not show any notable differences in either IL-10 or HO-1 expression, when compared to WT (data not shown).