2B, Supporting Fig. 1). Again, the segregation between progressors and nonprogressors is evident. We then tested 250 proteins, 154 up-regulated and 96 down-regulated, that define the clusters shown in Fig. 2, for confounding factors. HM781-36B The signature is robust against time (Fig. 2B), and all the potential confounding clinical factors are listed in Supporting

Fig. 3. The calculation of external isolation (a measure for how well individual biologic conditions separate) and internal cohesiveness (a measure for how well members of a single biological condition cluster together), and indicated in the different panels, allow quantification of this statement when compared with Fig. 2A and 2B. In conclusion, the subset of statistically significant differentially abundant proteins may indicate whether a patient will progress to severe liver disease posttransplantation. Consistent with the literature, we observed a significantly greater mean donor age in patients with rapidly progressive fibrosis (Table 1). The biological significance of the altered protein abundance pattern described above was further investigated by classifying the associated proteins within the context of biologically relevant functions using IPA. Patients with rapid fibrosis progression exhibited an enrichment of down-regulated proteins mapping to signaling or disease

pathways associated with hepatoprotective Linsitinib molecular weight activities, whereas up-regulated proteins

mapped to various immune response pathways (Table 2 and Supporting Table 6). With regard to the MCE latter, the representation of allograft rejection signaling pathways reflects the functional redundancy of proteins associated with inflammatory conditions attributed to viral recurrence or graft rejection, processes that are difficult to discern because they are histologically indistinguishable. We note that all patients received different combinations of immune-suppressing drugs, including treatment for graft rejection that trended with rapid fibrosis progression at 1 year posttransplantation (Table 1). However, we did detect differential regulation of biological processes such as proinflammatory innate immune activities and positive regulation of interferon gamma protein expression and downstream targets consistent with those described during the transcriptional deregulation associated specifically with HCV recurrence, rather than acute cellular rejection.23 Not surprisingly, patients with progressive liver disease further exhibited an enrichment of differentially regulated proteins mapping to the IPA toxicologic functional category of liver fibrosis, including proteins associated with hepatic stellate cell activation (P < 0.05), and demonstrate the possibility of detecting protein abundance profiles consistent with hepatic damage weeks or months prior to clinical evidence of liver injury.