As shown in Fig. 1A, sALT levels increased as early as 1 hour of reperfusion, peaked at 6 hours, and decreased thereafter. To determine the function of PD-1/B7-H1 negative signaling in the acute phase of liver IRI in this model, WT mice treated with B7-H1Ig were subjected to 90 minutes of partial

liver warm Tamoxifen datasheet ischemia followed by 6 hours or 24 hours of reperfusion. Unlike WT mice given control Ig, those conditioned with B7-H1Ig were resistant against IR-mediated hepatocellular damage, as evidenced by reduced sALT levels (163 ± 30 U/L versus 845 ± 166 U/L [6 hours], P < 0.01; 65 ± 2 U/L versus 216 ± 113 U/L [24 hours], P < 0.05) (Fig. 1B). These data correlated with histological criteria of liver damage at the peak of 6 hours postreperfusion (Fig. 1C). Control livers revealed severe lobular edema, congestion, ballooning, and hepatocellular necrosis (Suzuki score 2.33 ± 0.29 [6 hours]). In contrast, the B7-H1Ig group showed well-preserved liver architecture and histological detail without edema, vacuolization, or necrosis (Suzuki score 0.33 ± 0.58 [6 hours], P < 0.01). To determine whether this effect was dependent on stimulation of PD-1/B7-H1, a separate group of WT mice was treated with anti–B7-H1 mAb. Indeed, PD-1/B7-H1 selleck chemicals llc blockade re-created IR-triggered hepatocellular injury

and augmented liver damage compared with controls, as evidenced by increased sALT levels (1,497 ± 164 U/L [6 hours], 737 ± 264 U/L [24 hours], P < 0.05) (Fig. 1B), and deterioration of liver histology (Fig. 1C), reflected by the Suzuki score (3.83 ± 0.29 [6 hours], P < 0.01). We performed immunohistochemical staining of liver infiltrating cells at 6 hours of reperfusion following 90 minutes of warm ischemia. Treatment with B7-H1Ig diminished the number of cells per high-power field for T cells (0.5 ± 0.58 versus 2.0 ± 0.82, P < 0.05) ( Fig. 2A), neutrophils (2.0 ± 1.0 versus 53.7 ± 3.2, P < 0.001) (Fig. 2B), and macrophages (4.3 ± 1.0 versus 78.0 ± 2.0, P < 0.001) (Fig. 2) in the ischemic liver lobe compared with controls. Myeloperoxidase assay revealed that liver neutrophil activity was also

depressed in the treatment group compared with controls (0.03 ± 0.2 U/g versus 上海皓元 1.13 ± 0.3 U/g, P < 0.05) (Supporting Information Fig. 1). To assess the immunoregulatory mechanism of PD-1/B7-H1 activation, we contrasted intrahepatic T lymphocyte–related cytokine expression patterns in our model. B7-H1Ig significantly (P < 0.05) suppressed gene induction of Th1-type IFN-γ/granzyme B and largely abolished otherwise enhanced gene transcript levels of neutrophil/monocyte-derived proinflammatory chemokines (CXCL-1, CXCL-5, CCL-2, CXCL-10) and cytokines (TNF-α, IL-1β, IFN-β, IL-6) (P < 0.01) ( Fig. 3A,B). In contrast, Th2-type IL-10 but not IL-4 expression significantly (P < 0.01) increased after B7-H1Ig engagement (Fig. 3C).