05 at all time points; Fig. 4C,D). Because there was a difference in apoptosis after APAP dosing in CXCR2 knockout mice versus wild-type

controls as well as differences in caspase-3 activation, we next investigated if there were differences in prosurvival protein expression after APAP administration. Western blotting for the antiapoptotic proteins cIAP2, XIAP, Bcl-2, and Bcl-XL was performed on hepatic tissues 1, 2, 4, AZD1152-HQPA nmr and 6 or 8 hours after APAP administration. There were no differences in hepatic Bcl-2 or Bcl-XL expression (Fig. 5A-C). In contrast, cIAP2 expression increased in wild-type and CXCR2 knockout mice after APAP, with significant increases seen within 1 to 2 hours of APAP dosing; levels decreased to the baseline by 6 hours after APAP (Fig. 5D,E). Although significant cIAP increases were seen in wild-type and CXCR2 knockout mice with respect to control animals, there were no significant differences in cIAP levels in wild-type mice versus knockout mice at any time point. XIAP demonstrated the most significant differences in survival protein expression. Wild-type mice expressed minimal XIAP in response to APAP. In contrast, significant hepatic XIAP expression was seen after APAP in CXCR2 knockout mice (P < 0.01 at 2 and 4 hours; Fig. 5D,F). XIAP up-regulation

is controlled by activation of NF-κB p65 and p52.11, 12 To investigate if hepatic NF-κB p65 was activated in mice after APAP administration, we measured phosphorylated NF-κB p65 by immunoprecipitation and immunoblotting at various time points after APAP dosing. There was no evidence of activated 上海皓元医药股份有限公司 hepatic NF-κB p65 in wild-type or CXCR2 knockout mice after APAP LY2157299 cost (Fig. 6A). Next, we measured hepatic cytoplasmic and nuclear NF-κB p52 in knockout or wild-type mice after APAP. There was significant NF-κB p52 expression in both the cytoplasmic and nuclear hepatic proteins from CXCR2 knockout

mice treated with APAP. There was no detectable hepatic NF-κB p52 after APAP in wild-type mice (Fig. 6B-D). We examined hepatic JNK expression in wild-type and CXCR2 knockout mice after the administration of 375 mg/kg APAP to investigate whether CXCR2 signaling causes JNK activation. CXCR2 knockout and wild-type mice had a significant JNK increase after APAP. Hepatic JNK activation in wild types peaked 1 hour after APAP administration, gradually declined, and returned to the baseline at 12 hours; JNK activation in CXCR2 knockout mice was slower and weaker than that in wild-type mice (Fig. 6E,F). Less JNK activation was seen in CXCR2 knockout mice versus wild-type mice; this was statistically significant at 1 hour (P < 0.05). To determine whether the effects of CXCR2 signaling occur directly within hepatocytes rather than indirectly on other cell types within the liver, we measured CXCR2 expression on primary mouse hepatocytes; we used mouse neutrophils as a positive control because these cells are well known to express CXCR2.