Pharmacology of AMG 181, a human anti-α4 ß7 antibody that specifically alters trafficking of gut-homing T cells.

BACKGROUND AND PURPOSE: AMG 181 is a human anti-α4 ß7 antibody currently in phase 1 and 2 trials in subjects with inflammatory bowel diseases. AMG 181 specifically targets the α4 ß7 integrin heterodimer, blocking its interaction with mucosal addressin cell adhesion molecule-1 (MAdCAM-1), the principal ligand that mediates α4 ß7 T cell gut-homing. EXPERIMENTAL APPROACH: We studied the in vitro pharmacology of AMG 181, and the pharmacokinetics and pharmacodynamics of AMG 181 after single or weekly i.v. or s.c. administration in cynomolgus monkeys for up to 13 weeks. KEY RESULTS: AMG 181 bound to α4 ß7 , but not α4 ß1 or αE ß7 , and potently inhibited α4 ß7 binding to MAdCAM-1 (but not vascular cell adhesion molecule-1) and thus inhibited T cell adhesion. Following single i.v. administration, AMG 181 Cmax was dose proportional from 0.01 to 80 mg·kg(-1) , while AUC increased more than dose proportionally. Following s.c. administration, dose-proportional exposure was observed with single dose ranging from 5 to 80 mg·kg(-1) and after 13 weekly doses at levels between 20 and 80 mg·kg(-1) . AMG 181 accumulated two- to threefold after 13 weekly 80 mg·kg(-1) i.v. or s.c. doses. AMG 181 had an s.c. bioavailability of 80%. The linear elimination half-life was 12 days, with a volume of distribution close to the intravascular plasma space. The mean trend for the magnitude and duration of AMG 181 exposure, immunogenicity, α4 ß7 receptor occupancy and elevation in gut-homing CD4+ central memory T cell count displayed apparent correlations. CONCLUSIONS AND IMPLICATIONS: AMG 181 has in vitro pharmacology, and pharmacokinetic/pharmacodynamic and safety characteristics in cynomolgus monkeys that are suitable for further investigation in humans.

Use of echocardiography to assess function of hDAF-transgenic pig cardiac xenografts.

The current standard of hand palpation may not be a sensitive method to detect rejection in heterotopic heart xenotransplants (HHTx). We sought to assess the use of echocardiography to detect rejection of pig heart xenografts. Four cynomolgus monkeys received HHTx from hDAF-transgenic pigs. Immunosuppression was cyclophosphamide induction, cyclosporine, steroids, sodium mycophenolate, alphaGal trisaccharide polymer, +/-soluble complement receptor type 1. Echocardiography was performed immediately after HHTx and three times a week postoperatively. Contractility on echo was scored as 1(none), 2(severely impaired), 3(moderate to severely impaired), 4(moderately impaired), 5(mild to moderately impaired), 6(mildly impaired), or 7(normal). Left ventricle wall thickness (LVWT) was measured in the anterior, inferior, posterior, lateral, and septal walls, the average was calculated. Impaired contractility or increase in LVWT were considered rejection and treated with steroids (solumedrol 15 mg/kg IV for 3-5 days). Palpation score (4-strong to 1-none) was recorded daily. Myocardial biopsies were obtained infrequently. At the time of first rejection, all four monkeys had an increase in LVWT and a decrease in contractility on echocardiography. Steroid treatment enhanced contractility in four monkeys and decreased LVWT in three monkeys. Palpation score remained at four of four during initial rejection episodes. Decrease in contractility and increase in LVWT on echocardiography appear to signify graft injury because steroid treatment results in improvement. Compared to palpation, echocardiography is more sensitive for assessing function of heterotopic pig heart xenografts. Echocardiography has, therefore, the potential to detect and treat early rejection episodes of heterotopic heart xenografts in nonhuman primates. This may help to achieve longer graft survival.

Functional metabolic characteristics of intact pig livers during prolonged extracorporeal perfusion: potential for a unique biological liver-assist device.

BACKGROUND: The clinical development of liver-support devices based on perfusion of either pig hepatocytes cartridges or whole pig livers has been hampered by the ability to use sufficient liver cell mass to provide adequate metabolic support, limited perfusion times, and the potential for patient exposure to pig zoonotic diseases. METHODS: We designed an original system in which an isolated intact pig liver was perfused extracorporeally under physiological conditions in a closed loop circuit with allogeneic pig blood and constant monitoring of major physiological and functional parameters. The perfusion circuit further included an interface membrane to provide for separation of patient and liver perfusion circulation. RESULTS: Prolonged (6-21 hr) liver perfusion did not produce significant liver damage as reflected by modest rises in the levels of the serum transaminases, stability of main biochemical parameters (including potassium), and the maintenance of normal cellular morphology. Optimal liver function was documented as measured by lactate consumption, control of glycemia, and the results of clotting studies and functional assays. The perfused liver cleared 82% and 79% of peak bilirubin and ammonia concentrations with clearing kinetics identical throughout perfusion. Indocyanine green clearance was identical to that observed in the living donor before explant surgery. CONCLUSIONS: In conclusion, the extracorporeal pig liver perfusion apparatus described here allows optimal pig liver function for prolonged periods of time. The microporous membrane to provide separation of donor organ and recipient and the high level of functional activity suggest that this form of liver metabolic support may have important clinical applications.

Immunogenicity of antigens in boiled alginate microspheres.

Vaccine efficacy can be enhanced by delivery of antigens in synthetic microspheres. The process of antigen incorporation into microspheres can expose fragile antigens to damaging conditions, such as high temperatures, and to bacterial contamination. Maintenance of immunogenicity of several antigens and reduction of bacterial load in alginate microspheres following boiling was evaluated. Mice were immunized subcutaneously, initially and again 21 days later, with either non-boiled or boiled microspheres containing ovalbumin (OVA), a culture supernatant vaccine of Pasteurella haemolytica (PHV), or a potassium thiocyanate extract of P. multocida (PTE). Serum samples were obtained prior to immunization and at the time of euthanasia 28 days later. Culture of microspheres showed that boiling completely eliminated aerobic bacterial growth for OVA-containing microspheres, and reduced growth by a factor of 10(4) for PTE microspheres. More bacteria were cultured after boiling than before for PHV microspheres. ELISA performed on serum and intestinal lamina propria explant supernatants showed that immunogenicity of PHV microspheres was not altered by boiling. Boiled OVA microspheres were still able to stimulate a significant serum IgG anti-OVA titer in mice, but boiled PTE microspheres completely lacked immunogenicity. Elispot assays of spleens showed that only PHV microspheres were able to retain immunogenicity after boiling. Results indicate that boiling is not an effective means for reducing the bacterial load of alginate microspheres and that the process is associated with a diminution of vaccine immunogenicity.

Surgical treatment of hepatocellular carcinoma in cirrhosis.

Hepatocellular carcinoma is one of the most frequent forms of cancer worldwide and its diagnosis and treatment have changed substantially during the last few years. Recent advances in ultrasonography, spiral computed tomography scan and nuclear magnetic resonance have further simplified the diagnostic approach to hepatocellular carcinoma. Ultrasonography is the reference examination, giving a wide variety of information on tumour size, location, relationship with portal and hepatic veins and splanchnic haemodynamics. Surgical resection and liver transplantation can both be defined as curative treatment while other techniques such as percutaneous ethanol injection and chemoembolization must be considered as palliative. Therapeutic strategies for hepatocellular carcinoma are based upon data concerning the characteristics of the tumour the functional status of non-tumoural liver parenchyma and patients' general conditions. Surgery of hepatocellular carcinoma in cirrhotic liver is mainly restricted by lack of functional hepatic reserve and by the limited capacity of hepatic regeneration. The best surgical results are obtained in early tumoural stages which generally need limited resection. Nevertheless, major liver resections have a specific role in selected cases. Recurrence rate after surgical resection is high and is related to a large number of factors. For this reason, liver transplantation, removing at the same time, the tumour and the underlying disease, is considered, theoretically, the best treatment for hepatocellular carcinoma, but its role is still debated and limited by difficult organ sharing. Integration of present therapeutic schemes are under evaluation with promising preliminary results.

Oral vaccination of animals with antigens encapsulated in alginate microspheres.

Most infectious diseases begin at a mucosal surface. Prevention of infection must therefore consider ways to enhance local immunity to prevent the attachment and invasion of microbes. Despite this understanding, most vaccines depend on parenterally administered vaccines that induce a circulating immune response that often does not cross to mucosal sites. Administration of vaccines to mucosal sites induces local immunity. To be effective requires that antigen be administered often. This is not always practical depending on the site where protection is needed, nor comfortable to the patient. Not all mucosal sites have inductive lymphoid tissue present as well. Oral administration is easy to do, is well accepted by humans and animals and targets the largest inductive lymphoid tissue in the body in the intestine. Oral administration of antigen requires protection of antigen from the enzymes and pH of the stomach. Polymeric delivery systems are under investigation to deliver vaccines to the intestine while protecting them from adverse conditions that could adversely affect the antigens. They also can enhance delivery of antigen specifically to the inductive lymphoid tissue. Sodium alginate is a readily available, inexpensive polymer that can be used to encapsulate a wide variety of antigens under mild conditions. Orally administered alginate microspheres containing antigen have successfully induced immunity in mice to enteric (rotavirus) pathogens and in the respiratory tract in cattle with a model antigen (ovalbumin). This delivery system offers a safe, effective means of orally vaccinating large numbers of animals (and perhaps humans) to a variety of infectious agents.

[Role of surgery in the treatment of refractory ascites in cirrhotic patients]. / Place de la chirurgie dans le traitement de l'ascite réfractaire du cirrhotique.

Ascites, generally directly reflecting portal hypertension, is the commonest cause of hospitalisation in patients with cirrhosis. In almost 10% of patients with ascites, optimal medical treatment combining bed rest, salt and water restriction, and diuretic treatment, is unable to induce sodium excretion and decrease the volume of the ascites, corresponding to the definition of refractory ascites. In other cases, it is the treatment of ascites itself (salt and water restriction and diuretics) which induce complications: water and electrolyte disturbances, functional renal failure, encephalopathy, the development of which also corresponds to refractory ascites. The therapeutic armamentarium for the management of refractory ascites remains varied, with the use of aspiration of ascites with compensation, peritoneovenous shunts, transhepatic or surgical porto-systemic anastomoses, and finally, liver transplantation. At the present time, each therapeutic measure must be taken while keeping in mind the possibility of subsequent liver transplantation and the potential risk of compromising liver transplantation by inappropriate treatments. In this context, the authors review and analyse the respective places of the various therapeutic modalities in the management of refractory ascites in cirrhotic patients.

The humoral response to xenografts is controlled by a restricted repertoire of immunoglobulin VH genes.

BACKGROUND: The early phases of the host immune response to xenografts are dominated by anti-donor antibodies. The immunological pathways responsible for mediating the host humoral responses to xenografts are largely unknown, and this report addresses the nature of the immunoglobulin genes controlling the host antibody response to xenografts. METHODS: cDNA libraries established from rat anti-hamster monoclonal antibodies and splenic lymphocytes from LEW rats rejecting hamster heart xenografts were used to clone, sequence, and identify the immunoglobulin genes responsible for encoding rat xenoantibodies to hamster heart grafts. Libraries for germline variable region heavy chain (VH) genes encoding the anti-hamster xenograft antibodies were established by genomic DNA cloning and analyzed by nucleotide sequencing. The frequency of Ig VH gene usage for controlling the antibody responses to hamster xenografts was examined by colony-filter dot hybridization. The nucleic acid structure of these genes was then compared to their genomic progenitors to identify the number and structural diversity expressed by the Ig VH genes used to mediate the response. RESULTS: Rat monoclonal antibodies selected for their ability to precipitate the rejection of hamster xenografts exclusively use a closely related group of VH genes. The VH genes used by these antibodies are restricted to a single family of germline genes (VHHAR) for which 15 family members have been identified. The frequency of VHHAR gene usage in splenic IgM-producing B cells from LEW rats rapidly expands from 0.8% in naive animals to 13% in recipients 4 days after xenotransplantation. cDNA libraries expressing VHHAR genes were established from splenic lymphocytes derived from naive or xenograft recipients at 4 and 21 days after transplantation. Examination of 20 cDNA clones revealed that the majority (75%) of these clones express VHHAR genes displaying limited somatic mutation. CONCLUSIONS: The use of a closely related group of Ig VH genes in a germline configuration to control the early humoral response to xenografts suggests that this response may represent the utilization of a primitive, T cell-independent pathway of antibody production by the graft recipients.

Preoperative chemoembolization of hepatocellular carcinoma: a comparative study.

OBJECTIVE: To assess the efficacy and adverse effects of preoperative transcatheter chemoembolization (CE) on surgical resection, postoperative outcome, and recurrence of hepatocellular carcinoma. DESIGN: A before-after trial comparing a group of patients undergoing liver resection after CE (CE group) with a group of patients undergoing liver resection without prior CE (control group), matched for tumor size and underlying liver disease. SETTING: A tertiary care university hospital in a metropolitan area. PATIENTS: Twenty-four patients in each group, treated between 1986 and 1992. INTERVENTIONS: A mean of 1.6+/-0.2 preoperative CE procedures were performed per patient in the CE group. Tumorectomies, segmentectomies, and major liver resections were performed with a comparable frequency in each group. RESULTS: Overall, CE was not associated with a significant reduction of tumor size (7.8+/-1 cm prior to CE vs 7.1+/-1 cm after CE) or alpha-fetoprotein levels (2560+/-2091 microg/L prior to CE vs 1788+/-1270 microg/L after the last CE). Chemoembolization promoted tumor necrosis but did not influence tumor encapsulation, invasion of the capsule, venous permeation, presence of daughter nodules, or surgical margins. Liver resection was rendered more difficult by preoperative CE as a result of pediculitis and gallbladder lesions in 37% of patients, but the postoperative course was not altered. Disease-free survival (33%+/-12% vs 32%+/-12% at 3 years) and overall survival were comparable. CONCLUSIONS: Convincing evidence is lacking to support systematic preoperative CE in patients with initially resectable hepatocellular carcinoma. Further studies should aim to identify the subgroup of patients who may benefit from this neoadjuvant treatment.

Microbiological hazards related to xenotransplantation of porcine organs into man.

Pigs are emerging as the most likely providers of genetically engineered organs and cells for the purpose of clinical xenotransplantation. Introduction of clinical trials has been delayed primarily by uncertainties regarding the risk of swine pathogen transmission that could harm the recipient. The concern that xenotransplantation carries the potential for a new epidemic has been highlighted by recent experiences with both bovine spongiform encephalopathy and human immunodeficiency diseases. As clinical trials have been postponed and xenotransplantation teams are working actively to gather data for an estimation of the risk, this review provides the reader with a state-of-the-art estimation of the microbiological hazards related to xenotransplantation of porcine organs to man. Particular emphasis is put on viral and retroviral hazards. Both current diagnostic tools and those under development are described, along with breeding strategies to provide donor animals that would not put the recipient or the general population at risk.

Hepatectomy with hypothermic perfusion of the liver.

Whereas most liver resections can be performed within 60 min, the period of vascular clamping and resulting ischemia may prove too short to allow complex major liver resections (MLR) especially on diseased livers. To overcome this problem, cooling of the liver with 4 degrees C preservations solution routinely used in liver transplantation may be used in three different approaches to MLR: I "In situ": the liver remains in the abdomen and integrity of afferent and efferent vessels is conserved. II "Ex situ-in vivo": the liver exteriorized from the abdomen by transecting all hepatic veins, remains connected to the porta hepatis. III "Ex vivo": the liver being removed from the abdomen, the MLR is performed extracorporeally. Of 15 MLR reported here, 11 were performed "in situ" and 4 "ex situ-in vivo"/Nowadays, the liver surgeon's "toolbox" must contain hypothermic liver perfusion. In carefully selected cases, these techniques allow MLR on diseases livers or mandating complex vascular procedures.

Induction of pulmonary immunity in cattle by oral administration of ovalbumin in alginate microspheres.

Respiratory infectious diseases are an important cause of economic losses to the cattle industry. There is a need for an effective, easy to administer vaccine to the critical bacterial pathogens that cause pneumonia in cattle. An orally administered vaccine could be given to a large number of animals without significant stress to the animals and with minimal labor. The purpose of this study was to determine whether the oral administration of a model antigen (ovalbumin) in alginate microspheres could induce pulmonary immunity in cattle. Calves were vaccinated orally with ovalbumin (OVA) following either a subcutaneous (s.c.) or oral priming dose of OVA. Calves primed and boostered by oral administration (oral/oral) of OVA encapsulated in alginate microparticles had increased numbers of antigen-specific IgA ASCs (ASCs) in bronchoalveolar lavage (BAL) fluids. Calves that received a s.c. priming followed by an oral booster inoculation (s.c./oral) of OVA in alginate microspheres had a greater number of anti-OVA IgA, IgG1 and IgG2 ASCs in BALF. S.c./oral calves also had increased numbers of anti-OVA IgG1 ASCs in peripheral blood whereas oral/oral calves had none. S.c./oral calves had increased anti-OVA IgG1, IgG2, and IgA titers in BALF, and IgG1 and IgG2 in serum compared to both oral/oral and sham vaccinated calves. These results indicate that oral administration of antigen encapsulated in alginate microspheres results in a mucosal immune response in the respiratory tract of cattle. Furthermore, s.c. priming both enhanced the IgA response and stimulated an IgG1 and IgG2 response not seen in oral/oral calves. The difference in antibody isotype results suggest that design of the vaccination protocol can direct antibody responses as needed for a specific immunization program.

[Vascular clamping of the liver. Indications and limits]. / Les clampages vasculaires du foie. Indications et limites.

Control of bleeding during liver surgery is an essential prognostic factor for postoperative morbidity and mortality. Several well defined methods are currently available to ensure vascular occlusion, ranging from selective clamping of a segmental pedicle to total vascular exclusion of the liver. These methods of vascular control each have specific indications. However, they can induce ischaemia of the liver whose functional consequences, such as postoperative liver failure, are particularly severe in the case of prolonged ischaemia, affecting the remaining liver and in the presence of histological or functional alterations of the hepatic parenchyma. Selective methods of vascular control, only affecting the part of the liver to be resected, can be used systematically. In contrast, when the occlusion is not selective, they must be used sparingly, essentially in the case of bleeding from the parenchymal section, adopting the principal objective of the briefest possible total ischaemia. Minimization of bleeding must be weighed up against the consequences of ischaemia on the remaining liver, especially in the case of extensive hepatectomy, prolonged clamping and pathological non-neoplastic liver.

Major extended hepatic resections in diseased livers using hypothermic protection: preliminary results from the first 12 patients treated with this new technique.

BACKGROUND: Hepatic vascular exclusion allows the performance of major hepatic resections with minimal intraoperative blood loss. We have previously shown that normothermic ischemia can be tolerated by a healthy liver for up to 90 minutes, and this period is increased to 4 hours if the liver is cooled to 4 degrees C using University of Wisconsin solution. STUDY DESIGN: This study assessed whether these techniques could be successfully applied for patients requiring resection of a diseased liver, which is more sensitive to ischemic damage. Between July 1990 and May 1994, 12 patients (6 men, 6 women; mean age, 57.8 years) in whom the planned hepatic resection was believed to require hepatic vascular exclusion for more than 1 hour were treated with perfusion with the University of Wisconsin solution. The surgical procedures were right hepatectomy (one patient), extended right hepatectomy (seven patients), and extended left hepatectomy (four patients). The underlying hepatic disease was cirrhosis or severe fibrosis with hepatocellular carcinoma (four patients), cholestasis (due to cholangiocarcinoma and biliary stricture, one patient each), and more than 30 percent steatosis after treatment of hepatic metastases with chemotherapy (six patients). The University of Wisconsin solution that had been cooled to 4 degrees C was perfused through a cannula placed in the portal vein or the hepatic arterial branch of the segment to be resected, but with flow directed toward the liver that should be retained and effluent fluid drained through a cavotomy. Before reperfusion, the liver was rinsed with Ringer's lactate solution, which was also 4 degrees C. RESULTS: The mean duration of hepatic ischemia was 121 minutes (range, 65 to 250 minutes), and venovenous bypass was used in three cases. The mean amount of blood transfused intraoperatively was 4.3 +/- 4 U; four cases required no transfusion. One patient died on postoperative day seven of portal vein thrombosis. The median hospital stay was 21 days (range, 12 to 56 days). Postoperative complications consisted of pneumonia (one patient), liver insufficiency (one patient, who recovered spontaneously), and subphrenic abscess (one patient). The postoperative tests of hepatic function were altered to the same degree as that seen after hepatic vascular exclusion of less than 1-hour duration in healthy livers. All patients who left the hospital were alive at 1 year. CONCLUSIONS: Cooling of the hepatic parenchyma allowed us to perform major hepatic resection in patients with diseased livers using hepatic vascular exclusion for longer than 1 hour without increased morbidity or mortality. However, because of particular difficulties due to the size or location of the lesions, the application of these new techniques should only be considered for the largest and most complex hepatic resections for which hepatic vascular exclusions longer than 1 hour are foreseen.

Systemic and pulmonary immune response to intrabronchial administration of ovalbumin in calves.

Local immunization of the respiratory tract may be the best way to achieve protection against respiratory pathogens. In order to do so successfully, it is important to fully understand how the immune response to antigen administered via the respiratory route develops. We studied the respiratory and systemic immune response after subcutaneous (SC) and intrabronchial (IB) inoculation of calves with ovalbumin (OVA). Eight calves received two SC inoculations of OVA and eight other calves received two SC and three additional IB inoculations of OVA. The occurrence of OVA-specific antibodies and antibody-secreting cells (ASC) was measured over time using isotype-specific enzyme linked immunosorbent assay (ELISA) and ELISPOT. SC immunization of calves did not result in OVA-specific IgA in bronchoalveolar lavage (BAL) fluid. Subcutaneous priming followed by intrabronchial challenge caused an initial IgG1 response in the bronchoalveolar lavage fluid, followed by a large IgA response. The presence of IgG1-ASCs indicated that the IgG1 was at least partially locally produced. Most of the OVA-specific IgA in the BAL fluid was secreted by pulmonary ASCs as indicated by the large number of IgA-ASCs in BAL samples and the low serum level of OVA-specific IgA. Antigen-specific IgG1 ASCs were detectable among peripheral mononuclear cells after culture with OVA.