Novel antibodies that selectively block mouse IL-12 enable the re-evaluation of the role of IL-12 in immune protection and pathology.

The dimeric cytokine IL-12 is important in the control of various infections but also contributes to the pathology of certain diseases making it a potential target for therapy. However, its specific inhibition with antibodies is complicated by the fact that its two subunits are present in other cytokines: p40 in IL-23 and p35 in IL-35. This has led to erroneous conclusions like the alleged implication of IL-12 in experimental autoimmune encephalomyelitis (EAE). Here, we report the development of a mouse anti-mouse IL-12 vaccine and the production of monoclonal antibodies (mAbs) that do not react with p40 or p35 (in IL-35) but specifically recognize and functionally inhibit the IL-12 heterodimer. Using one of these mAbs, MM12A1.6, that strongly inhibited IFN-γ production and LPS-induced septic shock after viral infection, we demonstrate the critical role played by IL-12 in the rejection of male skin graft by female C57BL/6 syngeneic recipients and in the clearance of an immunogenic mastocytoma tumor variant by DBA/2 mice, but not in a parent to F1 immune aggression model nor in MOG-induced EAE, which was clearly prevented by anti-p40 mAb C17.8. Given this selective inhibition of IL-12, these mAbs provide new options for reassessing IL-12 function in vivo.

Laparoscopic left liver resections: how far can we go?

INTRODUCTION: The aim of this study was to analyse the outcomes of laparoscopic anatomic hepatectomies of the left liver segments. METHODS: This is a retrospective multicentre study including all patients operated on laparoscopically divided into unisegmentectomy of 2, 3 or 4 (Group 1), left lobectomy (or left lateral sectionectomy LLS) (Group 2), left hepatectomy (Group 3) and extended left hepatectomy (Group 4) between 2000 and 2016. These four groups were compared in terms of demographics, intraoperative data and postoperative outcomes. RESULTS: Among the 190 selected patients, the groups 1, 2, 3, 4 included 25 (13.2%), 116 (61.0%), 27 (14.2%) and 22 (11.6%) patients, respectively. The cohorts were comparable except for the number of lesions (p = 0.001) and tumour diameter (p = 0.004). The operative time, blood loss and the use of vascular clamping were more frequent in the Groups 3 and 4 (p = 0.0001), as is the rate of conversion to laparotomy (p = 0.001). Total morbidity was 23.3%, and major complications were more frequent in Group 4 (p = 0.0001). The prevalence of hepatic complications (11.6%), intra-abdominal collections (7.4%) and respiratory complications (3.7%) was proportionally correlated to the hepatectomy extension (p = 0.0001). CONCLUSION: All laparoscopic left liver resections seem safe and feasible even though extended hepatectomy is associated with a significant morbidity.

Impact of intraoperative blood loss on the short-term outcomes of laparoscopic liver resection.

BACKGROUND: Intraoperative blood loss is one of the predictors of outcome of open hepatectomy. But the impact of blood loss in laparoscopic hepatectomy (LH) on postoperative outcomes is poorly understood. The aim of this study is to analyze the association between blood loss and postoperative outcomes after LH. METHODS: A retrospective analysis of prospectively maintained database of patients undergoing LH from 1995 to 2016 was performed. The data were divided into two groups based on the extent of blood loss: Group 1 (<250 ml) and Group 2 (≥250 ml). The basic characteristics and postoperative outcomes were compared between these groups. RESULTS: A total of 504 patients underwent 611 LH (Group 1: 414 and Group 2: 197). The mean age was 62.4 years. The most common indication was liver secondaries (71.7%). Major hepatectomy was performed in 37% cases. Mean operative time was 225 ± 110.5 min and estimated blood loss was 239 ± 399.4 ml (range 0-4500 ml). Group 2 had significantly higher number of patients with malignant lesions undergoing major hepatectomy, anatomical resection with higher requirement for blood transfusion, and longer hospital stay. The incidence of conversion rate, overall complications including liver failure, renal failure, and postoperative mortality, was significantly higher in Group 2. However, the bile leak rate was similar in the two groups. CONCLUSION: Intraoperative blood loss is most frequent in patients undergoing major LH. Blood loss ≥250 ml during LH may adversely affect the postoperative outcomes.

A comparison of laparoscopic resection of posterior segments with formal laparoscopic right hepatectomy for colorectal liver metastases: a single-institution study.

INTRODUCTION: The benefit of by laparoscopic resection for lesions located in postero-superior segments is unclear. The present series aimed at comparing intraoperative and post-operative results in patients undergoing either laparoscopic RPS or laparoscopic RH for colorectal liver metastases located in the right postero-superior segments. METHODS: From 2000 to 2015, patients who underwent laparoscopic resection of segment 6 and/or 7 (RPS group) were compared with those with right hepatectomy (RH group) in terms of tumour characteristics, surgical treatment, and short-term outcomes. RESULTS: Among the 177 selected patients, 78 (44.1 %) had laparoscopic RPS and 99 (55.9 %) a laparoscopic RH. Among RPS patients, 26 (33.3 %) underwent anatomical resection of either segment 7, 8 or both. Three (3 %) patients undergoing RH died in the post-operative course and none in the RPS group. Sixty-three (35.5 %) patients experienced post-operative complications, including major complications in 24 (13.5 %) patients. Liver failure (17.1 vs. 0 %, p = 000.1), biliary leakage (6.0 vs. 1.2 %, p = 00.1), intra-abdominal collection (19.1 vs. 2.5 %, p = 000.1), and pulmonary complication (16.1 vs. 1.2 %, p = 000.1) were significantly increased in the RH group. CONCLUSION: The present series suggests that patients who underwent laparoscopic resection of CRLM located in the postero-superior segments developed significantly less complications than patients undergoing formal RH.

Risk factors and surgical management of anastomotic biliary complications after pediatric liver transplantation.

Biliary complications (BCs) still remain the Achilles heel of liver transplantation (LT) with an overall incidence of 10% to 35% in pediatric series. We hypothesized that (1) the use of alternative techniques (reduced size, split, and living donor grafts) in pediatric LT may contribute to an increased incidence of BCs, and (2) surgery as a first treatment option for anastomotic BCs could allow a definitive cure for the majority of these patients. Four hundred twenty-nine primary pediatric LT procedures, including 88, 91, 47, and 203 whole, reduced size, split, and living donor grafts, respectively, that were performed between July 1993 and November 2010 were retrospectively reviewed. Demographic and surgical variables were analyzed, and their respective impact on BCs was studied with univariate and multivariate analyses. The modalities of BC management were also reviewed. The 1- and 5-year patient survival rates were 94% and 90%, 89% and 85%, 94% and 89%, and 98% and 94% for whole, reduced size, split, and living donor liver grafts, respectively. The overall incidence of BCs was 23% (n = 98). Sixty were anastomotic complications [47 strictures (78%) and 13 fistulas (22%)]. The graft type was not found to be an independent risk factor for the development of BCs. According to a multivariate analysis, only hepatic artery thrombosis and acute rejection increased the risk of anastomotic BCs (P < 0.001 and P = 0.003, respectively). Anastomotic BCs were managed primarily with surgical repair in 59 of 60 cases with a primary patency rate of 80% (n = 47). These results suggest that (1) most of the BCs were anastomotic complications not influenced by the type of graft, and (2) the surgical management of anastomotic BCs may constitute the first and best therapeutic option.

Local immunostimulation leading to rejection of accepted male skin grafts by female mice as a model for cancer immunotherapy.

Female mice of inbred strain CBA do not reject syngeneic male skin grafts even though they mount a T-cell response against the male-specific HY antigen. We show that local immunostimulation performed by injecting cytokines and Toll-like receptor ligands in close vicinity to the graft causes rejection. We feel that this approach should be tested in tumor-bearing human patients in combination with antitumor vaccination. Relief of intratumor immunosuppression may increase considerably the fraction of patients who respond to vaccination directed against tumor antigens recognized by T cells.

Prope tolerance after pediatric liver transplantation.

pT, under mono- and infratherapeutic calcineurin inhibition, may constitute an optimal condition combining graft acceptance with low IS load and minimal IS-related toxicity. We reviewed 171 pediatric (<15.0 yr) survivors beyond one yr after LT, transplanted between April 1999 and June 2007 under tacrolimus-based regimens (median follow-up post-LT: 6.0 yr, range: 0.8-9.5 yr). Their current status regarding IS therapy was analyzed and correlated with initial immunoprophylaxis. pT was defined as tacrolimus monotherapy, with mean trough blood levels <4 ng/mL during the preceding year of follow-up, combined with normal liver function tests. The 66 children transplanted before April 2001 received a standard tacrolimus-steroid regimen. Beyond April 2001, 105 patients received steroid-free tacrolimus-basiliximab or tacrolimus-daclizumab immunoprophylaxis. In the latter group, 43 (41%) never experienced any acute rejection episode and never received steroids. In the long term, a total of 79 recipients (47%) developed pT (n = 73) or IS-free operational tolerance (n = 6), 27 of them belonging to the 43 steroid-free patients (63%). In contrast, only 52/128 (41%) children treated with steroids subsequently developed prope/operational tolerance (p = 0.012). Steroid-free tacrolimus-based IS seems to promote long-term graft acceptance under minimal/no IS. These results constitute the first evidence that minimization of IS, including steroid avoidance, might be tolerogenic in the long term after pediatric LT.

Impact of pre-transplant liver hemodynamics and portal reconstruction techniques on post-transplant portal vein complications in pediatric liver transplantation: a retrospective analysis in 197 recipients.

BACKGROUND AND OBJECTIVE: Portal vein (PV) complications are the most frequent vascular complications in pediatric liver transplant (LT). We hypothesized that pre-LT liver hemodynamic parameters and PV reconstruction technique could predict the risk of PV complications post-LT. METHODS: Three hundred seventy-three children had a primary LT. A detailed ultrasound study of the pre-LT native liver hemodynamics was available in 198 cases, with details of PV anastomosis available for 197 of these: end-to-end anastomosis (n = 146, 74%), interposition vein graft technique (n = 28, 14%), or portoplasty (latero-lateral anastomosis of vein graft and recipient PV) (n = 23, 12%). RESULTS: Overall 5-year patient survival rate was 90%. Among the 198 patients with pre-LT hemodynamic data, 79 (40%) had PV hypoplasia (diameter ≤4 mm), 64 (32%) had a pathological portal flow (nonhepatopetal flow), and 47 (24%) had an arterial resistance index (ARI) ≥1. Abnormal hemodynamics were mostly observed in biliary atresia (BA). Among these 3 parameters, only ARI ≥1 was significantly correlated with a higher rate of PV complications post-LT (P = 0.041). PV complication-free survival at 5 years were 91% for end-to-end anastomosis, 91% for portoplasty, and 62% for interposition vein graft technique (P = 0.002). At multivariate analysis, the use of an interposition vein graft was the only factor to be significantly associated with a higher rate of PV complications post-LT (P = 0.003). CONCLUSIONS: PV hypoplasia with liver hemodynamic disturbances was mainly observed in BA. Hepatic ARI ≥1 might be a good predictor of PV complications post-LT. Latero-lateral portoplasty seemed to provide the best results when end-to-end anastomosis is not feasible.

Peptide-specific, TCR-alpha-driven, coreceptor-independent negative selection in TCR alpha-chain transgenic mice.

As thymocytes differentiate, Ag sensitivity declines, with immature CD4-CD8- double-negative (DN) cells being most susceptible to TCR signaling events. We show that expression of alphabetaTCR from the DN3 stage lowers the threshold for activation, allowing recognition of MHC peptides independently of the TCR beta-chain and without either T cell coreceptor. The MHC class I-restricted C6 TCR recognizes the Y-chromosome-derived Ag HYK(k)Smcy. Positive selection in C6 alphabetaTCR females is skewed to the CD8 compartment, whereas transgenic male mice exhibit early clonal deletion of thymocytes. We investigated the effect of the HYK(k)Smcy complex on developing thymocytes expressing the C6 TCR alpha-chain on a TCR-alpha(-/-) background. On the original selecting haplotype, the skew to the CD8 lineage is preserved. This is MHC dependent, as the normal bias to the CD4 subset is seen on an H2b background. In male H2k C6 alpha-only mice, the presence of the HYK(k)Smcy complex leads to a substantial deletion of thymocytes from the DN subset. This phenotype is replicated in H2k C6 alpha-only female mice expressing an Smcy transgene. Deletion is not dependent on the beta variable segment of the C6 TCR or on a restricted TCR-beta repertoire. In contrast, binding of HYK(k)Smcy and Ag-specific activation of mature CD8+ T cells is strictly dependent on the original C6 beta-chain. These data demonstrate that, in comparison with mature T cells, alphabetaTCR+ immature thymocytes can recognize and transduce signals in response to specific MHC-peptide complexes with relaxed binding requirements.

The immunological monitoring of kidney and liver transplants in adult and pediatric recipients.

Over the last half century, kidney and liver transplantation have been recognized as the treatment of choice for adult and children with end-stage renal or liver failure. Infants present a relative naïve immune system, but they are capable of mounting both cellular and humoral immune responses to the foreign antigens presented by the allograft. Immune monitoring is a way of measuring functional and molecular correlates of immune reactivity which may provide clinically useful information for identifying patients who have an increase risk of acute rejection prior to clinical symptoms or develop transplant tolerance. However, although numerous assays have been shown to predict rejection, to date no assays have been demonstrated to detect or predict transplantation tolerance. This is a summary of the published literature on promising antigen-specific and non-antigen-specific assays used for immunological monitoring in solid organ transplantation. This work also attempts to review their applicability to pediatric transplantation, specifically, pediatric kidney and liver recipients.

Liver retransplantation in children. A 21-year single-center experience.

In this study, the epidemiology and outcome of graft loss following primary pediatric liver transplantation (LT) were analysed, with the hypothesis that early retransplantation (reLT) might be associated with lower immunologic risks when compared with late reLT. Between March 1984 and December 2005, 745 liver grafts were transplanted to 638 children at Saint-Luc University Hospital, Brussels. Among them, a total of 90 children (14%) underwent 107 reLT, and were categorized into two groups (early reLT, n = 58; late reLT, n = 32), according to the interval between either transplant procedures (< or >30 days). Ten-year patient survival rate was 85% in recipients with a single LT, vs. 61% in recipients requiring reLT (P < 0.001). Ten-year patient survival rates were 59% and 66% for early and late reLT, respectively (P = 0.423), the corresponding graft survival rates being 51% and 63% (P = 0.231). Along the successive eras, the rate of reLT decreased from 17% to 10%, whereas progressive improvement of outcome post-reLT was observed. No recurrence of chronic rejection (CR) was observed after reLT for CR (0 of 19). Two children developed a positive cross-match at reLT (two of 10, 20%), both retransplanted lately for CR secondary to immunosuppression withdrawal following a post-transplant lymphoproliferative disease. In summary, the results presented could not evidence better results for late reLT when compared with early reLT. The former did not seem to be associated with higher immunologic risk, except for children having withdrawal of immunosuppression following the first graft.

Monitoring tolerance after human liver transplantation.

The validation of reliable, non-invasive immunological assays evaluating anti-donor responsiveness in allograft recipients would provide a clinically relevant tool for the early detection of ongoing rejection process as well as for the identification of operational tolerance in the long term. A sequential approach towards immunological monitoring of allografts is proposed in this review: (i) investigations exploring the initial donor-recipient alloresponses, including the analysis of the cytokine network; (ii) investigations regarding graft acceptance and operational tolerance in long-term transplant patients, consisting in the analysis of regulatory T cells and of circulating precursors of dendritic cells, in the measurement of T cell alloreactivity as well as in the study of T cell receptor repertoires. Beside the conventional in vivo and in vitro immunological techniques, the potential applications of molecular imaging in transplantation also deserve further exploration, with particular respect to allograft immune monitoring. Enforced collaboration between transplant clinicians and immunologists will be required to develop the translational research protocols required for the development of immunological monitoring, within an international multicentric network.

Pediatric liver transplantation using left hepatic segments from living related donors: surgical experience in 100 recipients at Saint-Luc University Clinics.

Living-related liver transplantation was developed in the context of deceased donor organ shortage, which is particularly acute for pediatric recipients. This retrospective study analyzes the surgical technique and complications in the first 100 pediatric liver transplantation using left segmental liver grafts from living donors, performed at Saint-Luc University Clinics between July 1993 and April 2002. Pre-operative evaluation in donors and recipients, analysis of the surgical technique, and postoperative complications were reviewed. After a median follow-up period of 2526 days, no donor mortality was encountered, with a minimal morbidity and no long-term sequelae. At one and five yr post-transplantation, the actuarial patient survival rates were 94% and 92%, the corresponding figures being 92% and 89% for graft survival. The incidences of portal vein and hepatic artery thromboses, and of biliary complications were 14%, 1%, and 27%, respectively. Living-related liver transplantation in children constitutes an efficient therapy for liver failure to face the increased demand for liver grafts. Donor morbidity was kept to acceptable incidence, and surgical technique in the recipient needs to be tailored to minimize postoperative complications.

Stepwise minimization of the immunosuppressive therapy in pediatric liver transplantation. A conceptual approach towards operational tolerance.

The evolution of immunosuppression in pediatric liver transplantation has been characterized by a steady reduction of the immunosuppressive load, including removal of anti-lymphocyte antibodies, with the aim to reduce the incidence of EBV-related post-transplant lymphoproliferative disorders. Acute rejection rates were studied retrospectively over two decades of pediatric liver transplantation, according to the successive immunoprophylactic regimens. 318 primary pediatric liver transplant recipients, included between 1984 and 2004 in successive prospective trials, were analyzed, with respect to the impact of the immunosuppressive protocol on acute rejection occurrence. A progressive decrease of rejection incidences was observed, which corresponded to reduced immunosuppressive load and to transplant eras. Such trend might be related to changing approaches towards acute rejection histology and therapy by transplant clinicians, but also to the stepwise minimization of immunosuppressive protocols, putatively enhancing graft acceptance. We hypothesize that the recent population of liver transplant recipients with low immunosuppression might be more suitable for progressive immunosuppression withdrawal trial, with the aim to reach ultimately operational tolerance.

PELD score and posttransplant outcome in pediatric liver transplantation: a retrospective study of 100 recipients.

BACKGROUND: Pediatric End-stage Liver Disease (PELD) score is proposed as an objective tool to prioritize children awaiting liver transplantation (LT), higher PELD being associated with increased pre-LT mortality. This study investigated whether PELD may also impact on post-LT results. METHODS: PELD was retrospectively analyzed in 100 pediatric recipients of a primary LT from living-related (n = 49) or postmortem donors (PMD, n = 51). The main pre-LT diagnosis was biliary atresia (n = 64), hepatic malignancy and fulminant hepatitis cases being excluded. PELD was calculated in all patients at the time of pre-LT assessment. Considering the median delay of 117 days between listing and LT in the PMD subgroup, a second PELD was calculated at the time of LT, allowing the determination of a delta PELD during the waiting period. PMD grafts were allocated using an allocation system taking into account waiting times as well as medical urgency, operative at EuroTransplant. RESULTS: Overall 5-year actuarial patient and graft survivals were 96% and 91%, respectively. PELD at listing (13.3 +/- 9.7) showed a normal statistical distribution. PELD scores at listing and at LT were not found to significantly impact on post-LT outcome (NS). In contrast, higher delta PELD might be associated with lower posttransplant patient survival (p = 0.094). CONCLUSIONS: The results of this retrospective analysis suggest that giving priority to high PELD recipients may not result in worsening post-LT outcome. Accordingly, these data support such "sickest children first" allocation policy, which should contribute to reduce pre-LT mortality without worsening post-LT results and increasing organ waste.