Prolonged Cold Ischemia Time Results in Local and Remote Organ Dysfunction in a Murine Model of Vascularized Composite Transplantation.

Vascularized composite allotransplantation (VCA) is a viable reconstructive option for complex tissue defects. Although grafts with a large muscular component may be uniquely susceptible to ischemia-reperfusion (I/R) syndrome, the safe cold ischemia time in VCA has not been established. We investigated the effects of cold ischemia on innate immune response and recipient survival in a murine orthotopic hindlimb transplantation model. Surprisingly, mice receiving grafts exposed to 6 h or longer of cold storage demonstrated reduced survival and massive elevations in serum creatinine, blood urea nitrogen, and creatine kinase, compared with 1 h of cold storage recipients. This was accompanied by progressive increase in macrophage and neutrophil cell infiltration in muscle biopsy specimens, altered platelet endothelial cell adhesion molecule-1 expression, and ultimate renal injury. Multiplex immunoassay analysis identified 21 cytokines in serum and 18 cytokines in muscle biopsy specimens that are likely essential in the complex response to I/R-triggered injury in VCA. In conclusion, this study, in a mouse model of orthotopic hindlimb transplantation, is the first to document that prolonged cold ischemia triggers progressive I/R injury with vascular endothelial damage and may lead to irrecoverable local and remote organ damage. These experimental findings are important in guiding future therapies for human VCA recipients.

A Soluble Form of P Selectin Glycoprotein Ligand 1 Requires Signaling by Nuclear Factor Erythroid 2-Related Factor 2 to Protect Liver Transplant Endothelial Cells Against Ischemia-Reperfusion Injury.

Liver endothelial cell (LEC) damage is essential in the pathogenesis of ischemia-reperfusion injury (IRI) in transplant recipients. We analyzed the mechanism of LEC resistance against IRI by using a novel recombinant soluble form of P selectin glycoprotein ligand 1, tandem P selectin glycoprotein ligand immunoglobulin (TSGL-Ig), in a mouse model of hepatic cold preservation (4°C in University of Wisconsin solution for 20 h) and syngeneic orthotopic liver transplantation (OLT). Unlike controls, TSGL-Ig protected orthotopic liver transplants against ischemia-reperfusion (IR) stress, shown by depressed serum alanine aminotransferase levels, well-preserved hepatic architecture, and improved survival (42% vs. 92%). TSGL-Ig suppressed neutrophil/macrophage sequestration and proinflammatory cytokine/chemokine programs in OLT. Treatment with TSGL-Ig mitigated LEC activation (P and E selectin, VCAM-1 and intercellular adhesion molecule 1 expression). In parallel in vitro studies, TSGL-Ig diminished cellular damage in H2 O2 -stressed LEC cultures (lactic acid dehydrogenase and alanine aminotransferase levels). Increased thioredoxin, glutamate-cysteine ligase, NAD(P)H quinone dehydrogenase 1, and hypoxia-inducible factor 1α expression, along with transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2), implied that TSGL-Ig exerts antioxidant functions in IR-stressed OLT and H2 O2 -stressed LECs. Indeed, Nrf2-deficient livers suffered fulminant IRI compared with WT despite concomitant TSGL-Ig therapy. Thus, TSGL-Ig is not only acting as a competitive antagonist blocking leukocyte migration into IR-stressed liver, but it may also act directly as an agonist stimulating Nrf2-mediated cytoprotection in LECs. This study supports the role of P selectin signaling in hepatic homeostasis in OLT, with broad implications for tissue damage conditions.

Liver transplantation for "very early" intrahepatic cholangiocarcinoma: International retrospective study supporting a prospective assessment.

UNLABELLED: The presence of an intrahepatic cholangiocarcinoma (iCCA) in a cirrhotic liver is a contraindication for liver transplantation in most centers worldwide. Recent investigations have shown that "very early" iCCA (single tumors ≤2 cm) may have acceptable results after liver transplantation. This study further evaluates this finding in a larger international multicenter cohort. The study group was composed of those patients who were transplanted for hepatocellular carcinoma or decompensated cirrhosis and found to have an iCCA at explant pathology. Patients were divided into those with "very early" iCCA and those with "advanced" disease (single tumor >2 cm or multifocal disease). Between January 2000 and December 2013, 81 patients were found to have an iCCA at explant; 33 had separate nodules of iCCA and hepatocellular carcinoma, and 48 had only iCCA (study group). Within the study group, 15/48 (31%) constituted the "very early" iCCA group and 33/48 (69%) the "advanced" group. There were no significant differences between groups in preoperative characteristics. At explant, the median size of the largest tumor was larger in the "advanced" group (3.1 [2.5-4.4] versus 1.6 [1.5-1.8]). After a median follow-up of 35 (13.5-76.4) months, the 1-year, 3-year, and 5-year cumulative risks of recurrence were, respectively, 7%, 18%, and 18% in the very early iCCA group versus 30%, 47%, and 61% in the advanced iCCA group, P = 0.01. The 1-year, 3-year, and 5-year actuarial survival rates were, respectively, 93%, 84%, and 65% in the very early iCCA group versus 79%, 50%, and 45% in the advanced iCCA group, P = 0.02. CONCLUSION: Patients with cirrhosis and very early iCCA may become candidates for liver transplantation; a prospective multicenter clinical trial is needed to further confirm these results. (Hepatology 2016;64:1178-1188).

Postoperative atrial fibrillation in liver transplantation.

Postoperative atrial fibrillation (POAF) is common after major surgeries and is associated with increased morbidity and mortality. POAF after liver transplantation (LT) has not been reported. This study was undertaken to investigate the incidence, impact, and risk factors of POAF in LT patients. After IRB approval, LT between January 2006 and August 2013 at our center were retrospectively reviewed. POAF that occurred within 30 days after LT was included. Patients with and without POAF were compared and independent risk factors were identified by logistic regression. Of 1387 adults LT patients, 102 (7.4%) developed POAF during the study period. POAF was associated with significantly increased mortality, graft failure, acute kidney injury and prolonged hospital stay. Independent risk factors included age, body weight, MELD score, presence of previous history of AF, the vasopressors use prior to LT and pulmonary artery diastolic pressure at the end of LT surgery (odds ratios 2.0-7.2, all p < 0.05). A risk index of POAF was developed and patients with the high-risk index had more than 60% chance of developing POAF. These findings may be used to stratify patients and to guide prophylaxis for POAF in the posttransplant period.

Hyperglycemia and liver ischemia reperfusion injury: a role for the advanced glycation endproduct and its receptor pathway.

Although pretransplant diabetes is a risk factor for mortality post-liver transplant, the underlying mechanism has not been fully defined. In a murine liver partial warm ischemia model, we addressed the question of how diabetes/hyperglycemia impacted tissue inflammatory injuries against ischemia reperfusion (IR), focusing on the advanced glycation endproduct (AGE) and its receptor (RAGE) pathway. Our results showed that hepatocellular injury was exacerbated in streptozotocin-induced diabetic mice against IR, in association with hyper-inflammatory immune activation in livers. Serum levels of AGEs, but not HMGB1, were increased in diabetic mice in response to liver IR. Both RAGE antagonist peptides and small interfering RNA alleviated liver injuries and inhibited inflammatory immune activation against IR in diabetic, but not normal, mice. Kupffer cells (KCs)/macrophages, but not hepatocytes, from diabetic mice expressed significantly higher levels of RAGE, leading to their hyper-inflammatory responsiveness to both TLR ligands and AGEs. In vitro, hyperglycemia increased macrophage RAGE expression and enhanced their TLR responses. Our results demonstrated that activation of the AGE-RAGE signaling pathway in KCs was responsible for hyper-inflammatory immune responses and exacerbated hepatocellular injuries in diabetic/hyperglycemic hosts against liver IR.

ATF6 mediates a pro-inflammatory synergy between ER stress and TLR activation in the pathogenesis of liver ischemia-reperfusion injury.

Although the roles of the metabolic stress in organ ischemia-reperfusion injury (IRI) have been well recognized, the question of whether and how these stress responses regulate innate immune activation against IR remains unclear. In a murine liver partial warm ischemia mode, we showed that prolonged ischemia triggered endoplasmic reticulum (ER) stress response, particularly, the activating transcription factor 6 (ATF6) branch, in liver Kupffer cells (KCs) and altered their responsiveness against Toll-like receptor (TLR) stimulation. Ischemia-primed cells increased pro-, but decreased anti-, inflammatory cytokine productions. Alleviation of ER stress in vivo by small chemical chaperon 4-phenylbutyrate or ATF6 small interfering RNA (siRNA) diminished the pro-inflammatory priming effect of ischemia in KCs, leading to the inhibition of liver immune response against IR and protection of livers from IRI. In vitro, ATF6 siRNA abrogated the ER stress-mediated pro-inflammatory enhancement of macrophage TLR4 response, by restricting NF-κB and restoring Akt activations. Thus, ischemia primes liver innate immune cells by ATF6-mediated ER stress response. The IR-induced metabolic stress and TLR activation function in synergy to activate tissue inflammatory immune response.

Randomized, double-blind trial of anidulafungin versus fluconazole for prophylaxis of invasive fungal infections in high-risk liver transplant recipients.

Invasive fungal infections (IFIs) are a common complication in liver transplant recipients. There are no previous randomized trials of an echinocandin for the prevention of IFIs in solid organ transplant recipients. In a randomized, double-blind trial conducted at University-affiliated transplant centers, 200 high-risk liver transplant recipients (100 patients per group) received either anidulafungin or fluconazole for antifungal prophylaxis. Randomization was stratified by Model for End-Stage Liver Disease score ≥30 and receipt of a pretransplant antifungal agent. The primary end point was IFI in a modified intent-to-treat analysis. The overall incidence of IFI was similar for the anidulafungin (5.1%) and the fluconazole groups (8.0%) (OR 0.61, 95% CI 0.19-1.94, p = 0.40). However, anidulafungin prophylaxis was associated with less Aspergillus colonization or infection (3% vs. 9%, p = 0.08), lower breakthrough IFIs among patients who had received pretransplant fluconazole (0% vs. 27%, p = 0.07), and fewer cases of antifungal resistance (no cases vs. 5 cases). Both drugs were well-tolerated. Graft rejection, fungal-free survival, and mortality were similar for both groups. Thus, anidulafungin and fluconazole have similar efficacy for antifungal prophylaxis in most liver transplant recipients. Anidulafungin may be beneficial if the patient has an increased risk for Aspergillus infection or received fluconazole before transplantation.

Liver transplantation in recipients receiving renal replacement therapy: outcomes analysis and the role of intraoperative hemodialysis.

The Model for End-Stage Liver Disease (MELD) system has dramatically increased the number of recipients requiring pretransplant renal replacement therapy (RRT) prior to liver transplantation (LT). Factors affecting post-LT outcomes and the need for intraoperative RRT (IORRT) were analyzed in 500 consecutive recipients receiving pretransplant RRT, including comparisons among recipients not receiving IORRT (No-IORRT, n = 401), receiving planned IORRT (Pl-IORRT, n = 70), and receiving emergent, unplanned RRT after LT initiation (Em-IORRT, n = 29). Despite a median MELD of 39, overall 30-day, 1-, 3- and 5-year survivals were 93%, 75%, 68% and 65%, respectively. Em-IORRT recipients had significantly more intraoperative complications (arrhythmias, postreperfusion syndrome, coagulopathy) compared with both No-IORRT and Pl-IORRT and greater 30-day graft loss (28% vs. 10%, p = 0.004) and need for retransplantation (24% vs. 10%, p = 0.099) compared with No-IORRT. A risk score based on multivariate predictors of IORRT accurately identified recipients with chronic (sensitivity 84%, specificity 72%, concordance-statistic [c-statistic] 0.829) and acute (sensitivity 93%, specificity 61%, c-statistic 0.776) liver failure requiring IORRT. In this largest experience of LT in recipients receiving RRT, we report excellent survival and propose a practical model that accurately identifies recipients who may benefit from IORRT. For this select group, timely initiation of IORRT reduces intraoperative complications and improves posttransplant outcomes.

Targeting TIM-1 on CD4 T cells depresses macrophage activation and overcomes ischemia-reperfusion injury in mouse orthotopic liver transplantation.

Hepatic injury due to cold storage followed by reperfusion remains a major cause of morbidity and mortality after orthotopic liver transplantation (OLT). CD4 T cell TIM-1 signaling costimulates a variety of immune responses in allograft recipients. This study analyzes mechanisms by which TIM-1 affects liver ischemia-reperfusion injury (IRI) in a murine model of prolonged cold storage followed by OLT. Livers from C57BL/6 mice, preserved at 4°C in the UW solution for 20 h, were transplanted to syngeneic recipients. There was an early (1 h) increased accumulation of TIM-1+ activated CD4 T cells in the ischemic OLTs. Disruption of TIM-1 signaling with a blocking mAb (RMT1-10) ameliorated liver damage, evidenced by reduced sALT levels and well-preserved architecture. Unlike in controls, TIM-1 blockade diminished OLT expression of Tbet/IFN-γ, but amplified IL-4/IL-10/IL-22; abolished neutrophil and macrophage infiltration/activation and inhibited NF-κB while enhancing Bcl-2/Bcl-xl. Although adoptive transfer of CD4 T cells triggered liver damage in otherwise IR-resistant RAG(-/-) mice, adjunctive TIM-1 blockade reduced Tbet transcription and abolished macrophage activation, restoring homeostasis in IR-stressed livers. Further, transfer of TIM-1(Hi) CD4+, but not TIM-1(Lo) CD4+ T cells, recreated liver IRI in RAG(-/-) mice. Thus, TIM-1 expressing CD4 T cells are required in the mechanism of innate immune-mediated hepatic IRI in OLTs.

Fibronectin-α4ß1 interactions in hepatic cold ischemia and reperfusion injury: regulation of MMP-9 and MT1-MMP via the p38 MAPK pathway.

Liver ischemia-reperfusion injury (IRI) remains a challenging problem in clinical settings. The expression of fibronectin (FN) by endothelial cells is a prominent feature of the hepatic response to injury. Here we investigate the effects of the connecting segment-1 (CS-1) peptide therapy, which blocks FN-α4ß1 integrin leukocyte interactions, in a well-established model of 24-h cold liver IRI. CS-1 peptides significantly inhibited leukocyte recruitment and local release of proinflammatory mediators (COX-2, iNOS and TNF-α), ameliorating liver IRI and improving recipient survival rate. CS1 therapy inhibited the phosphorylation of p38 MAPK, a kinase linked to inflammatory processes. Moreover, in addition to downregulating the expression of matrix metalloproteinase-9 (MMP-9) in hepatic IRI, CS-1 peptide therapy depressed the expression of membrane type 1-matrix metalloproteinase (MT1-MMP/MMP-14) by macrophages, a membrane-tethered MMP important for focal matrix proteolysis. Inhibition of p38 MAPK activity, with its pharmacological antagonist SB203580, downregulated MMP-9 and MT1-MMP/MMP-14 expressions by FN-stimulated macrophages, suggesting that p38 MAPK kinase pathway controls FN-mediated inductions of MMP-9 and MT1-MMP/MMP-14. Hence, this study provides new insights on the role of FN in liver injury, which can potentially be applied to the development of new pharmacological strategies for the successful protection against hepatic IRI.

The first report of orthotopic liver transplantation in the Western world.

Until the present time, the first experimental liver transplant which led to the development of human liver transplantation is attributed to C. Stuart Welch who performed a heterotopic transplant in the canine species in 1955. In 1956, Jack Cannon is credited with the first animal orthotopic liver transplant although the species was not disclosed. This report is intended to set the historical record straight by acknowledging that Vittorio Staudacher in 1952 was the first to perform a liver transplant in a large animal model.

Disruption of Type-I IFN pathway ameliorates preservation damage in mouse orthotopic liver transplantation via HO-1 dependent mechanism.

Ischemia/reperfusion injury (IRI) remains unresolved problem in clinical organ transplantation. We analyzed the role of Type-I interferon (IFN) pathway in a clinically relevant murine model of extended hepatic cold preservation followed by orthotopic liver transplantation (OLT). Livers from Type-I IFN receptor (IFNAR) knockout (KO) or wild-type (WT) mice (C57/BL6) were harvested, preserved at 4°C in UW solution for 20 h and transplanted to groups of syngeneic IFNAR KO or WT recipients. Liver graft but not recipient IFNAR deficiency was required to consistently ameliorate IRI in OLTs. Indeed, disruption of Type-I IFN signaling decreased serum alanine aminotransferase (sALT) levels (p < 0.001), diminished Suzuki's score of histological OLT damage (p < 0.01) and improved 14-day survival (from 42%[5/12] in WT to 92%[11/12] in IFNAR KO; p < 0.05). Unlike in WT group, IFNAR deficiency attenuated OLT expression of TNF-α, IL-1ß, IL-6, MCP-1, CXCL-10, ICAM-1; diminished infiltration by macrophages/PMNs; and enhanced expression of antioxidant HO-1/Nrf2. The frequency of TUNEL+ apoptotic cells and caspase-3 activity/expression selectively decreased in IFNAR KO group. Small interfering (si)RNA-directed targeting of HO-1 restored cardinal features of liver IRI in otherwise resistant IFNAR-deficient OLTs. Thus, intact Type-I IFN signaling is required for hepatic IRI, whereas HO-1 is needed for cytoprotection against innate immunity-dominated organ preservation damage in IFNAR-deficient liver transplants.

Liver ischemia and reperfusion injury: new insights into mechanisms of innate-adaptive immune-mediated tissue inflammation.

Ischemia and reperfusion injury (IRI) is a dynamic process that involves two distinctive yet interrelated phases of ischemic organ damage and inflammation-mediated reperfusion injury. Although multiple cellular and molecular pathways contribute and regulate tissue/organ damage, integration of different players into a unified mechanism is warranted. The crosstalk between innate and adaptive immune systems plays a significant role in the pathogenesis of liver IRI. In this review, we focus on recent progress in the mechanism of liver innate immune activation by IR. Kupffer cells (KC), DCs, NK, as well as T cells initiate local inflammation response, the hallmark of IRI, by utilizing distinctive immune receptors to recognize and/or trigger various molecules, both endogenous and exogenous. The interlocked molecular signaling pathways in the context of multiple liver cell types, the IRI kinetics and positive versus negative regulatory loops in the innate immune activation process are discussed. Better appreciation of molecular interactions that mediate these intricate cascades, should allow for the development of novel therapeutic approached against IRI in liver transplant recipients.

Sotrastaurin, a protein kinase C inhibitor, ameliorates ischemia and reperfusion injury in rat orthotopic liver transplantation.

Sotraustaurin (STN), a small molecule, targeted protein kinase C (PKC) inhibitor that prevents T-lymphocyte activation via a calcineurin-independent pathway, is currently being tested in Phase II renal and liver transplantation clinical trials. We have documented the key role of activated T cells in the inflammation cascade leading to liver ischemia/reperfusion injury (IRI). This study explores putative cytoprotective functions of STN in a clinically relevant rat model of hepatic cold ischemia followed by orthotopic liver transplantation (OLT). Livers from Sprague-Dawley rats were stored for 30 h at 4°C in UW solution, and then transplanted to syngeneic recipients. STN treatment of liver donors/recipients or recipients only prolonged OLT survival to >90% (vs. 40% in controls), decreased hepatocellular damage and improved histological features of IRI. STN treatment decreased activation of T cells, and diminished macrophage/neutrophil accumulation in OLTs. These beneficial effects were accompanied by diminished apoptosis, NF-κB/ERK signaling, depressed proapoptotic cleaved caspase-3, yet upregulated antiapoptotic Bcl-2/Bcl-xl and hepatic cell proliferation. In vitro, STN decreased PKCθ/IκBα activation and IL-2/IFN-γ production in ConA-stimulated spleen T cells, and diminished TNF-α/IL-1ß in macrophage-T cell cocultures. This study documents positive effects of STN on liver IRI in OLT rat model that may translate as an additional benefit of STN in clinical liver transplantation.

Major challenges limiting liver transplantation in the United States.

Liver transplantation is the gold standard of care in patients with end-stage liver disease and those with tumors of hepatic origin in the setting of liver dysfunction. From 1988 to 2009, liver transplantation in the United States grew 3.7-fold from 1713 to 6320 transplants annually. The expansion of liver transplantation is chiefly driven by scientific breakthroughs that have extended patient and graft survival well beyond those expected 50 years ago. The success of liver transplantation is now its primary obstacle, as the pool of donor livers fails to keep pace with the growing number of patients added to the national liver transplant waiting list. This review focuses on three major challenges facing liver transplantation in the United States and discusses new areas of investigation that address each issue: (1) the need for an expanded number of useable donor organs, (2) the need for improved therapies to treat recurrent hepatitis C after transplantation and (3) the need for improved detection, risk stratification based upon tumor biology and molecular inhibitors to combat hepatocellular carcinoma.

Posttransplantation hepatitis B prophylaxis with combination oral nucleoside and nucleotide analog therapy.

Liver transplant recipients are at risk of developing recurrent hepatitis B after liver transplantation for hepatitis B virus (HBV)-related liver disease. We evaluated the efficacy of a new hepatitis B prophylaxis regimen involving conversion from at least 12 months of HBIg with lamivudine to combination therapy with an oral nucleoside and nucleotide analog. Between June 2008 and May 2010, a total of 61 liver transplant recipients were converted to a combination of a nucleoside and nucleotide analog. The mean (±standard deviation) follow-up time after conversion was 15.0 (±6.1) months. Recurrent HBV occurred in two (3.3%) patients at 3.1 and 16.6 months after HBIg cessation. The overall person time incidence rate for HBV recurrence after HBIg cessation was 2.7 cases per 100 person-years. The estimate of HBV recurrence was 1.7% at 1 year after HBIg cessation. HBIg cessation a minimum of 12 months after liver transplantation with subsequent combination therapy with a nucleoside and nucleotide analog provides effective prophylaxis against recurrent HBV infection. The clinical implications of HBsAg detection without clinical, biochemical or molecular manifestations of recurrent hepatitis B require further study.

rPSGL-Ig for improvement of early liver allograft function: a double-blind, placebo-controlled, single-center phase II study.

The selectin antagonist known as recombinant P-selectin glycoprotein ligand IgG (rPSGL-Ig) blocks leukocyte adhesion and protects against transplantation ischemia reperfusion injury (IRI) in animal models. This randomized (1:1) single-center double-blind 47-patient phase 2 study with 6-month follow-up assessed rPSGL-Ig's safety and impact on early graft function at 1 mg/kg systemic dose with pretransplant allograft ex vivo treatment in deceased-donor liver transplant recipients. Safety was assessed in all patients, whereas efficacy was assessed in a prospectively defined per-protocol patient set (PP) by peak serum transaminase (TA) and bilirubin values, and normalization thereof. In PP patients, the incidence of poor early graft function (defined as peak TA >2500 U/L or bilirubin >10 mg/dL), average peak liver enzymes and bilirubin, normalization thereof and duration of primary and total hospitalization trended consistently lower in the rPSGL-Ig group compared to placebo. In patients with donor risk index above study-average, normalization of aspartate aminotransferase was significantly improved in the rPSGL-Ig group (p < 0.03). rPSGL-Ig treatment blunted postreperfusion induction versus placebo of IRI biomarker IP-10 (p < 0.1) and augmented cytoprotective IL-10 (p < 0.05). This is the first clinical trial of an adhesion molecule antagonist to demonstrate a beneficial effect on liver transplantation IRI and supported by therapeutic modulation of two hepatic IRI biomarkers.

Pediatric health-related quality of life after intestinal transplantation.

As outcomes after ITx improve, greater emphasis is needed on HRQOL. The primary aims of this study were to (i) assess the feasibility of measuring HRQOL in pediatric ITx recipients, (ii) measure HRQOL using validated instruments, and (iii) compare HRQOL in ITx recipients to healthy normal (NL) children. The CHQ and Pediatric Quality of Life (PedsQL4.0) instruments were administered to both patients and parents at outpatient visits. All 24 eligible patients were enrolled. The median age at study enrollment was 6.0 yr (range: 2-18 yr), and the median time from transplant to study enrollment was 2.8 yr (range: 0.5-11.8 yr). The majority of subjects were male (58%), Latino (58%), and liver-inclusive (92%) recipients. For CHQ and PedsQL4.0, parental responses were significantly lower in multiple categories including physical health and social functioning compared to healthy norms. Patient responses were not different from NL using CHQ but using PedsQL4.0 were significantly lower in the school functioning subcategory and psychosocial health summary score. HRQOL as reported by children and families after ITx is significantly lower in multiple categories compared to NL.

Alloimmune activation enhances innate tissue inflammation/injury in a mouse model of liver ischemia/reperfusion injury.

The deleterious sensitization to donor MHC Ags represents one of the most challenging problems in clinical organ transplantation. Although the role of effector/memory T cells in the rejection cascade has been extensively studied, it remains unknown whether and how these 'Ag-specific' cells influence host innate immunity, such as tissue inflammation associated with ischemia and reperfusion injury (IRI). In this study, we analyzed how allogeneic skin transplant (Tx) affected the sequel of host's own liver damage induced by partial warm ischemia and reperfusion. Our data clearly showed that allo-Tx recipients had increased inflammatory response against IR insult in their native livers, as evidenced by significantly more severe hepatocelluar damage, compared with syngeneic Tx recipient controls, and determined by serum ALT levels, liver histology (Suzuki's score) and intrahepatic proinflammatory gene inductions (TNF-alpha, IL-1beta and CXCL10). The CD4 T cells, but neither CD8 nor NK cells, mediated the detrimental effect of allo-Ag sensitization in liver IRI. Furthermore, CD154, but not IFN-gamma, was the key mechanism in allo-Tx recipients to facilitate IR-triggered liver damage. These results provide new evidence that alloreactive CD4 T cells are capable of enhancing innate tissue inflammation and organ injury via an Ag-nonspecific CD154-dependent but IFN-gamma independent mechanism.

Cytoprotective effects of a cyclic RGD peptide in steatotic liver cold ischemia and reperfusion injury.

The serious need for expanding the donor population has attracted attention to the use of steatotic donor livers in orthotopic liver transplantation (OLT). However, steatotic livers are highly susceptible to hepatic ischemia-reperfusion injury (IRI). Expression of fibronectin (FN) by endothelial cells is an important feature of hepatic response to injury. We report the effect of a cyclic RGD peptide with high affinity for the alpha5beta1, the FN integrin receptor, in a rat model of steatotic liver cold ischemia, followed by transplantation. RGD peptide therapy ameliorated steatotic IRI and improved the recipient survival rate. It significantly inhibited the recruitment of monocyte/macrophages and neutrophils, and depressed the expression of pro-inflammatory mediators, such as inducible nitric oxide synthase (iNOS) and interferon (IFN)-gamma. Moreover, it resulted in profound inhibition of metalloproteinase-9 (MMP-9) expression, a gelatinase implied in leukocyte migration in damaged livers. Finally, we show that RGD peptide therapy reduced the expression of the 17-kDa active caspase-3 and the number of apoptotic cells in steatotic OLTs. The observed protection against steatotic liver IRI by the cyclic RGD peptides with high affinity for the alpha5beta1 integrin suggests that this integrin is a potential therapeutic target to allow the successful utilization of marginal steatotic livers in transplantation.