The role of donor-specific anti-human leukocyte antigen antibodies (DSAs) that develop late after living donor liver transplantation is unknown. Seventy-nine pediatric recipients who had good graft function and underwent protocol liver biopsy more than 5 years after transplantation (median ¼ 11 years, range ¼ 5-20 years) were reviewed. DSAs were determined with the Luminex single-antigen bead assay at the time of the last biopsy, and complement component 4d (C4d) immunostaining was assessed at the times of the last biopsy and the previous biopsy. The donor specificity of antibodies could be identified in 67 patients: DSAs were detected in 32 patients (48%), and they were usually against human leukocyte antigen class II (30 cases) but were rarely against class I (2 cases). These patients had a higher frequency of bridging fibrosis or cirrhosis (28/32 or 88%) than DSA-negative patients (6/35 or 17%, P < 0.001). Fibrosis was likely to be centrilobular-based. DSA-positive patients, in comparison with DSA-negative patients, had higher frequencies of diffuse/focal endothelial C4d staining (P < 0.001) and mild/ indeterminate acute rejection [15/32 (47%) versus 5/35 (14%), P ¼ 0.004]. Four DSA-negative patients were off immunosuppression, whereas no patients in the DSA-positive group were (P ¼ 0.048). In conclusion, the high prevalence of graft fibrosis and anti-class II DSAs in late protocol biopsy samples suggests that humoral alloreactivity may contribute to the process of unexplained graft fibrosis late after liver transplantation.

The newly discovered T-cell immunoglobulin mucin (TIM) gene family molecules, expressed by T cells, regulate host immunity and tolerance. Although CD4+ T cells mediate innate immunity-dominated liver ischemia-reperfusion injury (IRI), the underlying mechanisms remain obscure. We have recently documented the novel function of TIM-1 pathway in the mechanism of liver IRI and also found that TLR4 activation plays a key triggering role. Using an anti-TIM-3 Ab, we now studied the role of TIM-3 signaling in the model of partial warm liver ischemia followed by reperfusion. Anti-TIM-3 Ab therapy exacerbated the liver damage, as compared with controls. Histological examination has revealed that anti-TIM-3 Ab augmented the hepatocellular damage, increased local neutrophil infiltration, facilitated local accumulation of T cells/macrophages and promoted liver cell apoptosis. Intrahepatic neutrophil activity, induction of pro-inflammatory cytokines/chemokines and expression of cleaved caspase-3/NF-NB/TLR4 were all increased in the treatment group. In parallel, anti-TIM-3 Ab and anti-galectin-9 (Gal-9; TIM-3 ligand) Ab increased IFN-γ production in ConA-stimulated spleen T cells, and TNFα/IL-6 expression in ConA-stimulated macrophage/T cell co-culture system. Interestingly, anti-TIM-3 Ab treatment did not affect liver IRI in TLR4-deficient (KO) mice. In conclusion, TIM-3 blockade exacerbated local inflammation and liver damage, suggesting importance of TIM-3/Gal-9 signaling in the maintenance of hepatic homeostasis. TIM-3-TLR4 cross regulation determined the severity of liver IRI in TLR4-dependent manner, a novel finding of potential importance to modulate tissue innate vs. adaptive responses in liver transplant patients. Thus, harnessing physiological negative T cell co-stimulation signaling on hepatic T cells may minimize innate immunity-mediated liver tissue damage.

The T cell immunoglobulin and mucin domain-containing molecules (TIM) protein family, which is expressed by T cells, plays a crucial role in regulating host adaptive immunity and tolerance. However, its role in local inflammation, such as innate immunity-dominated organ ischemia-reperfusion injury (IRI), remains unknown. Liver IRI occurs frequently after major hepatic resection or liver transplantation. Using an antagonistic anti-TIM-1 antibody (Ab), we studied the role of TIM-1 signaling in the model of partial warm liver ischemia followed by reperfusion. Anti-TIM-1 Ab monotherapy ameliorated the hepatocellular damage and improved liver function due to IR, as compared with controls. Histological examination has revealed that anti-TIM-1 Ab treatment decreased local neutrophil infiltration, inhibited sequestration of T lymphocytes, macrophages, TIM-1 ligand-expressing TIM-4 ؉ cells, and reduced liver cell apoptosis. Intrahepatic neutrophil activity and induction of proinflammatory cytokines/ chemokines were also reduced in the treatment group. In parallel in vitro studies, anti-TIM-1 Ab suppressed interferon-␥ (IFN-␥) production in concanavalin A (conA)-stimulated spleen T cells, and diminished tumor necrosis factor ␣ (TNF-␣)/interleukin (IL)-6 expression in a macrophage/spleen T cell coculture system. This is the first study to provide evidence for the novel role of TIM-1 signaling in the mechanism of liver IRI. TIM-1 regulates not only T for the role of cell activation but may also affect macrophage function in the local inflammation response. These results provide compelling data for further investigation of TIM-1 pathway in the mechanism of IRI, to improve liver function, expand the organ donor pool, and improve the overall success of liver transplantation. (HEPATOLOGY 2010;51:1363-1372 T he T cell immunoglobulin mucin (TIM) family of cell surface proteins has attracted much attention as potential regulators of the immune system. The TIM family is located on chromosome 11B1.1 in mice and consists of four identified members (TIM-1, -2, -3, and -4) and four putative members . In humans, the TIM family is located on chromosome 5q33.2 and consists of three members, TIM-1, TIM-3, and TIM-4. All are predicted to be type I membrane proteins that share a characteristic immunoglobulin

Programmed death-1 (PD-1)/B7-H1 costimulation acts as a negative regulator of host alloimmune responses. Although CD4 T cells mediate innate immunity-dominated ischemia and reperfusion injury (IRI) in the liver, the underlying mechanisms remain to be elucidated. This study focused on the role of PD-1/B7-H1 negative signaling in liver IRI. We used an established mouse model of partial liver warm ischemia (90 minutes) followed by reperfusion (6 hours). Although disruption of PD-1 signaling after anti-B7-H1 monoclonal antibody treatment augmented hepatocellular damage, its stimulation following B7-H1 immunoglobulin (B7-H1Ig) fusion protected livers from IRI, as evidenced by low serum alanine aminotransferase levels and well-preserved liver architecture. The therapeutic potential of B7-H1 engagement was evident by diminished intrahepatic T lymphocyte, neutrophil, and macrophage infiltration/activation; reduced cell necrosis/apoptosis but enhanced anti-necrotic/apoptotic Bcl-2/Bcl-xl; and decreased proinflammatory chemokine/ cytokine gene expression in parallel with selectively increased interleukin (IL)-10. Neutralization of IL-10 re-created liver IRI and rendered B7-H1Ig-treated hosts susceptible to IRI. These findings were confirmed in T cell-macrophage in vitro coculture in which B7-H1Ig diminished tumor necrosis factor-a/IL-6 levels in an IL-10-dependent manner. Our novel findings document the essential role of the PD-1/B7-H1 pathway in liver IRI. Conclusion: This study is the first to demonstrate that stimulating PD-1 signals ameliorated liver IRI by inhibiting T cell activation and Kupffer cell/macrophage function. Harnessing mechanisms of negative costimulation by PD-1 upon T cell-Kupffer cell cross-talk may be instrumental in the maintenance of hepatic homeostasis by minimizing organ damage and promoting IL-10-dependent cytoprotection. (HEPATOLOGY 2010;52:1380-1389

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To analyze the risk factors in the development of hepatic artery thrombosis (HAT) and assess the impact of our perioperative management for HAT on the long-term outcome after pediatric living donor liver transplantation (LDLT), we reviewed 382 patients under 12 yr of age who underwent 403 LDLT from January 1996 to December 2005. One- and 10-yr patient survival rates were 78% and 78% in the patients with HAT (27 patients; 6.7%), and 84% and 76% in the patients without HAT, respectively (p = n.s.). Univariate analysis showed gender (female), body weight (lower), and graft-to-recipient weight ratio (higher) were significant risk factors in the patients with HAT (p < 0.05). Patients with Doppler ultrasound signal loss of the hepatic artery (HA) accompanied by an increase of liver enzymes underwent thrombectomy and reanastomosis (S-group, n = 13), and patients with a weak HA signal underwent anticoagulant therapy (M-group, n = 13). One patient underwent re-LDLT. One- and five-yr patient survival rates were 83% and 83% in the S-group, and 77% and 77% in the M-group (p = n.s.). The incidence of biliary complications in the S-group (58%) was significantly higher than that of the M-group (15%). For a successful long-term outcome, the early detection of HAT and prompt medical and surgical intervention are crucial to minimize the insult of HAT.

Background A neutrophil elastase (NE) inhibitor, Sivelestat, has been approved for the treatment of acute lung injury associated with systemic inflammation in humans. Some reports have also shown its protective effects in liver inflammatory states. We have recently documented the importance of NE in the pathophysiology of liver ischemia and reperfusion injury (IRI), a local Ag-independent inflammation response. This study was designed to explore putative cytoprotective functions of clinically available Sivelestat in liver IRI. Methods Partial warm ischemia was produced in the left and middle hepatic lobes of C57BL/6 mice for 90 min, followed by 6 or 24 h of reperfusion. Mice were given Sivelestat (100 mg/kg, s.c.) at 10 min prior to ischemia, 10 min prior to reperfusion, and at 1 h and 3 h of reperfusion thereafter. Results Sivelestat treatment significantly reduced serum ALT levels and NE activity, as compared with controls. Histological liver examination has revealed that unlike in controls, Sivelestat ameliorated the hepatocellular damage and decreased local neutrophil activity and infiltration. The expression of pro-inflammatory cytokines (TNF-α, IL-6), chemokines (CXCL-1, CXCL-2, CXCL-10) and TLR4 was significantly reduced in the treatment group, along with diminished apoptosis via caspase-3 pathway. Moreover, in vitro studies confirmed downregulation of pro-inflammatory cytokine and chemokine programs in mouse macrophage cell cultures, along with depression of innate TLR4 signaling. Conclusion Sivelestat-mediated NE inhibition may represent an effective therapeutic option in liver transplantation and other inflammation disease states.

Anti-AT1R Ab and DSA-DRB1 may be candidates as biomarkers of graft fibrosis; both HLA and non-HLA immunity may be involved in graft fibrosis after IS withdrawal.