Complement levels in patients with hepatic dysfunction

Effect of Target-Mediated Disposition on Iptacopan Clinical Pharmacokinetics in Participants with Normal or Impaired Hepatic Function

Iptacopan, a first-in-class complement factor B inhibitor acting proximally in the alternative complement pathway, has been shown to be safe and effective for patients with complement-mediated diseases. Iptacopan selectively binds with high affinity to factor B, a soluble, plasma-based, hepatically produced protein. Factor B is abundant in the circulation but can be saturated at the iptacopan clinical dose of 200 mg twice daily. Iptacopan pharmacokinetics (PK) are influenced by target binding. This target-mediated drug disposition (TMDD) behavior makes PK data useful for understanding target occupancy and motivates modeling of drug-target binding to connect exposure with pharmacological effect. A phase I hepatic impairment (HI) PK study measuring both total and unbound iptacopan PK profiles provided an opportunity to characterize the effect of variation in target concentration (due to varying hepatic function) on iptacopan PK. HI caused no change in total iptacopan exposure but increased unbound iptacopan exposure 1.38- to 3.72-fold in participants with mild, moderate, or severe HI relative to demographically matched participants with normal hepatic function, with the largest increases in severe HI. A two-site competitive binding model was developed to elucidate the relationship between iptacopan PK and factor B occupancy to characterize exposure thresholds for maximal target engagement. The model was used to assess alternative dose regimens to provide insight into how to approach dose recommendations for patients with severe HI. This study provides an example of small-molecule TMDD, a behavior typically associated with targeted biologics; its importance is too often underappreciated in small-molecule drug development.

A Rare and Intriguing Case of Wilson's Disease Initially Suspected of Systemic Lupus Erythematosus

When systematic lupus erythematosus-like lab results (e.g., positive anti-double-stranded DNA antibody, low complement component 3) are inconsistent with physical findings, such as the absence of arthritis or nephritis, clinicians should consider diagnoses such as Wilson's disease, especially in the presence of abnormal liver function and elevated international normalized ratio (INR).

Supplementation of Paraformic Acid as a Substitute for Antibiotics in the Diet Improves Growth Performance and Liver Health in Broiler Chickens

The current study aimed to explore the effects of supplementing paraformic acid (PFA) into broilers’ diet on growth performance, inflammatory responses, and liver protection. A total of 567 healthy one-day-old broilers were used in a 42-d study, and they were randomized into three groups. Broilers were fed a basal diet (CON group) or the basal diet supplemented with either 50 mg/kg aureomycin (AB group) or 1000 mg/kg PFA (PFA group). The results showed that the PFA and AB groups had a higher feed conversion rate than the CON group from day 21 to 42 (p < 0.05). Dietary PFA or aureomycin supplementation decreased serum levels of interleukin (IL)-1β, IL-6, IL-10, alanine transaminase, diamine oxidase, and D-lactate, and significantly increased serum concentrations of immunoglobulin (Ig) A, IgM, and complement C4 (p < 0.05). Moreover, dietary PFA or aureomycin supplementation decreased hepatic levels of caspase-1, NOD-like receptor family pyrin domain containing 3 (NLRP3), tumor necrosis factor-alpha, IL-6, and IL-18, as well as NF-κB mRNA expression (p < 0.05). Above all, PFA supplementation into the broilers’ diet improved growth performance, inhibited inflammatory responses, and benefited liver protection. The protective effects of PFA on the liver might be related to inhibition of caspase-1-induced pyroptosis via inactivating the NF-κB/NLRP3 inflammasome axis in broiler chickens.

Complement System in Alcohol-Associated Liver Disease

Innate immunity contributes effectively to the development of Alcohol-Associated liver disease (ALD). Particularly, human studies and murine models of ALD have shown that Complement activation plays an important role during the initial and later stages of ALD. The Complement System may contribute to the pathogenesis of this disease since it has been shown that ethanol-derived metabolic products activate the Complement cascade on liver membranes, leading to hepatocellular damage. However, studies evaluating the plasma levels of Complement proteins in ALD patients present contradictory results in some cases, and do not establish a well-marked role for each Complement component. The impairment of leukocyte chemoattractant activity observed in these patients may contribute to the susceptibility to bacterial infections in the latter stages of the disease. On the other hand, murine models of ALD have provided more detailed insights into the mechanisms that link the Complement System to the pathogenesis of the disease. It has been observed that Classical pathway can be activated via C1q binding to apoptotic cells in the liver and contributes to the development of hepatic inflammation. C3 contributes to the accumulation of triglycerides in the liver and in adipose tissue, while C5 seems to be involved with inflammation and liver injury after chronic ethanol consumption. In this review, we present a compendium of studies evaluating the role of Complement in human and murine models of ALD. We also discuss potential therapies to human ALD, highlighting the use of Complement inhibitors.

Roles of the complement system in alcohol-induced liver disease

Alcohol-induced liver disease (ALD) is a complex disorder, with a disease spectrum ranging from steatosis to steatohepatitis, cirrhosis, and hepatocellular carcinoma. Although the pathogenesis of ALD is incompletely understood and currently no effective drugs are available for ALD, several lines of evidence suggest that complement activation and oxidative stress play crucial roles in the pathogenesis of ALD. Complement activation can regulate the production of ROS and influence oxidative stress in ALD. Precise regulation of the complement system in ALD may be a rational and novel avenue to postpone and even reverse the progression of disease and simultaneously promote the repair of liver injury. In this mini-review, we briefly summarize the recent research progress, especially focusing on the role of complement and oxidative stress-induced transfer RNA-derived fragments, which might help us to better understand the pathogenesis of ALD and provide aid in the development of novel therapeutic strategies for ALD.

Wilson disease and lupus nephritis: is it coincidence or a true association?

A 12-year-old girl born to third-degree consanguineous parents presented with recurrent episodes of haematuria for 8 months in association with peri-orbital and lower limb oedema for 20 days. There was no jaundice, hepatomegaly or neurological abnormality at presentation. An older brother had died following jaundice at 10 years of age. Urinalysis showed multiple dysmorphic erythrocytes without proteinuria and there was leucopenia, thrombocytopenia and hypo-albuminaemia (23 g/L). C₃ component of complementaemia was low and anti-nuclear antibodies and anti-double-stranded DNA antibodies were strongly positive by immunofluorescence. Systemic lupus erythematosus (SLE) was considered but the severe hypo-albuminaemia was unexplained. During the pre-renal biopsy work-up, a deranged coagulation profile with raised transaminases prompted evaluation for chronic liver disease which culminated in the diagnosis of Wilson disease. Treatment with penicillamine and immunosuppressants was initiated, but there was neurological deterioration on Day 30 of admission and she died owing to worsening liver failure on the Day 41. Post-mortem liver biopsy demonstrated cirrhosis and post-mortem renal biopsy showed features of class-II lupus nephritis. Auto-immune antibodies and autoimmune disorders have been reported in Wilson disease and there are anecdotal reports of an association of SLE with Wilson disease. However, this case is unique in that lupus nephritis was the presenting manifestation before Wilson disease was diagnosed. The underlying pathophysiological mechanisms of this association requires further research.

Pig Liver Xenotransplantation: A Review of Progress Toward the Clinic

Experience with clinical liver xenotransplantation has largely involved the transplantation of livers from nonhuman primates. Experience with pig livers has been scarce. This brief review will be restricted to assessing the potential therapeutic impact of pig liver xenotransplantation in acute liver failure and the remaining barriers that currently do not justify clinical trials. A relatively new surgical technique of heterotopic pig liver xenotransplantation is described that might play a role in bridging a patient with acute liver failure until either the native liver recovers or a suitable liver allograft is obtained. Other topics discussed include the possible mechanisms for the development of the thrombocytopenis that rapidly occurs after pig liver xenotransplantation in a primate, the impact of pig complement on graft injury, the potential infectious risks, and potential physiologic incompatibilities between pig and human. There is cautious optimism that all of these problems can be overcome by judicious genetic manipulation of the pig. If liver graft survival could be achieved in the absence of thrombocytopenia or rejection for a period of even a few days, there may be a role for pig liver transplantation as a bridge to allotransplantation in carefully selected patients.

Daclatasvir and Asunaprevir Combination Therapy-induced Hepatitis and Cholecystitis with Coagulation Disorder due to Hypersensitivity Reactions

A 70-year-old woman with chronic hepatitis C was admitted to our hospital due to liver injury, cholecystitis, and disseminated intravascular coagulation with a fever and skin rash. She had been on a combination regimen of daclatasvir and asunaprevir for 2 weeks of a 24-week regimen. Because of the symptoms, laboratory findings, results of a drug-induced lymphocyte stimulation test, and pathological findings of liver biopsy, we diagnosed her with drug-induced liver injury. Although daclatasvir and asunaprevir combination therapy is generally well-tolerated, some serious adverse effects have been reported. Our findings indicate that immunoallergic mechanisms were associated with daclatasvir and asunaprevir-induced liver injury.

Complement activation in acetaminophen-induced liver injury in mice

Overdose with acetaminophen (APAP) results in acute liver failure in humans and experimental animals. Complement comprises more than 30 proteins that can participate in tissue injury and/or repair, but the role of complement activation in APAP-induced hepatotoxicity has not been evaluated. Treatment of male, C57BL6J mice with APAP (200-400 mg/kg) resulted in liver injury as evidenced by increased activity of alanine aminotransferase (ALT) in plasma and hepatocellular necrosis. Plasma concentration of the complement component C3 was significantly reduced 6 h after treatment with APAP, indicating complement activation, and C3b (detected by immunostaining) accumulated in the centrilobular areas of liver lobules. Pretreatment with cobra venom factor (CVF; 15 U/mouse) to deplete complement components abolished APAP-mediated C3b accumulation, and this was accompanied by reductions in plasma ALT activity, hepatocellular necrosis, hepatic neutrophil accumulation, and expression of inflammatory genes (interleukin-6, interleukin-10, and plasminogen activation inhibitor-1) at 24 h after APAP treatment. Loss of hepatocellular GSH was similar in APAP-treated mice pretreated with either saline or CVF, suggesting that CVF pretreatment did not affect APAP bioactivation. Mice with a genetic deficiency in C3 had reduced ALT activity 6 and 12 h after APAP administration compared with wild-type animals. These results reveal a key role for complement activation in hepatic inflammation and progression of injury during the pathogenesis of APAP-induced hepatotoxicity.

Effect of alcohol drinking and cigarette smoking on neutrophil functions in adults

In recent years, the effects of smoking and excessive alcohol consumption on immune function have been studied, due to a high prevalence of infection or cancer in heavy drinkers, and the combination of smoking and drinking was considered to be a carcinogenic risk. However, the effect of smoking and drinking on systemic immune function has yet to be clearly understood. In this study, we investigated neutrophil functions (reactive oxygen species (ROS) productive activity, phagocytic ability and serum opsonic activity) and their relationship with alcohol consumption or amount of smoking. In total there were 731 male and female adult subjects who participated in the Iwaki Health Promotion Project in 2005. Multiple regression analysis showed a trend of increased ROS production in male subjects and a statistically significant decrease was observed in phagocytic activity caused by smoking in female subjects. In other words, oxidative stress caused by smoking in male subjects may be involved in ROS production from neutrophils. Decreased phagocytic activity of neutrophils caused by smoking suggests that host defense functions were impaired in female subjects. A relationship between neutrophil functions and the amount of alcohol consumption was not observed.

An in vitro model of pig liver xenotransplantation--pig complement is associated with reduced lysis of wild-type and genetically modified pig cells

BACKGROUND

After pig liver transplantation in humans, the graft will produce pig complement (C). We investigated in vitro the lysis of wild-type (WT), α1,3-galactosyltransferase gene-knockout (GTKO), and CD46 transgenic (CD46) pig peripheral blood mononuclear cells (PBMC) caused by human anti-pig antibodies (Abs) + pig C.

METHODS

Human serum IgM/IgG binding to WT and GTKO PBMC was determined by flow cytometry, and lysis of pig PBMC by a C-dependent cytotoxicity assay using (i) human serum (human Abs + C), (ii) GTKO pig serum (anti-Gal Abs + pig C), (iii) heat-inactivated human serum (human Abs) + rabbit C, or (iv) human Abs + pig C (serum).

RESULTS

Binding of human IgM and IgG to GTKO PBMC was less than to WT PBMC (P < 0.05). In the presence of human Abs, lysis of WT and GTKO PBMC by rabbit C was 87 and 13%, respectively (WT vs. GTKO, P < 0.01), but was only 37 and 0.4% in the presence of pig C (WT vs. GTKO, P < 0.05). Human/rabbit C-induced lysis was greater than pig C-induced lysis for both WT and GTKO PBMC. CD46 pig PBMC reduced rabbit/human C- and pig C-mediated lysis (P < 0.05).

CONCLUSIONS

Pig livers, particularly from GTKO and CD46 pigs, are likely to have an immunologic advantage over other organs after transplantation into humans. In the absence of pig antibodies directed to human tissues, pig complement is unlikely to cause problems after liver xenotransplantation, especially if GTKO/CD46 pigs are used as the source of the livers.

Liver xenografts for the treatment of acute liver failure: clinical and experimental experience and remaining immunologic barriers

A critical element restricting the application of liver transplantation is the shortage of human deceased donor organs. Xenotransplantation using pig organs might be a solution to this shortage. Although the problems that still require resolution include the immunologic barrier, the potential risk of transferring infectious agents with the transplanted organ, and uncertainty about whether the transplanted organ will function satisfactorily in the human environment, recent progress in the genetic manipulation of pigs has led to the prospect that clinical xenografting, at least as a bridge to allotransplantation, may be possible in the foreseeable future. Experience with clinical auxiliary and orthotopic liver xenotransplantation and experimental liver xenotransplantation in nonhuman primate and other large animal models is reviewed, and the remaining immunologic problems are discussed. Evidence suggests that, in patients with hepatic failure, the pig liver may be less susceptible to antibody-mediated injury than other pig organs, such as the heart or kidney. Pig Kupffer cells and other macrophages will recognize and phagocytose primate red blood cells, but this problem should be overcome by pretransplant depletion of macrophages from the organ-source pig. From the evidence currently available, it does not seem unduly optimistic to anticipate that a liver from an alpha1,3-galactosyltransferase gene-knockout pig would survive at least long enough to function as a successful bridge to allotransplantation.

Complement factor 5 is a quantitative trait gene that modifies liver fibrogenesis in mice and humans

Fibrogenesis or scarring of the liver is a common consequence of all chronic liver diseases. Here we refine a quantitative trait locus that confers susceptibility to hepatic fibrosis by in silico mapping and show, using congenic mice and transgenesis with recombined artificial chromosomes, that the gene Hc (encoding complement factor C5) underlies this locus. Small molecule inhibitors of the C5a receptor had antifibrotic effects in vivo, and common haplotype-tagging polymorphisms of the human gene C5 were associated with advanced fibrosis in chronic hepatitis C virus infection. Thus, the mouse quantitative trait gene led to the identification of an unknown gene underlying human susceptibility to liver fibrosis, supporting the idea that C5 has a causal role in fibrogenesis across species.

Efficacy of double-filtration plasmapheretic cross-circulation with a high-permeability membrane using canine harvested liver in porcine fulminant hepatic failure model

INTRODUCTION

The use of bioartificial liver devices requires. A sufficient liver cell mass to provide adequate metabolic support, reduction of xenogeneic immune reactions, and avoidance of viral transmission. We have developed a plasmapheresis system using a semipermeable membrane combined with canine whole liver perfusion (PMCWLP). In this study, we investigated the efficacy of our system in a porcine fulminant hepatic failure (FHF) model.

METHODS

The porcine FHF model was established by intraportal administration of alpha-amanitin (0.1 mg/kg) and lipopolysaccharide (1 microg/kg). Nine hours after drug injection, xenogenic perfusion treatment was performed twice within 6 hours (n = 5). As the plasmapheresis device, we used a hollow-fiber module with cellulose diacetate porous fibers (pore size, 0.05 microm, surface area, 2 m2). The canine whole liver was perfused with modified Krebs solution, which is commonly used in many laboratories, containing albumin (2 g/dL) and glucose (300 mg/dL). Control pigs (n = 10), had the circuit not connected to the whole canine liver.

RESULTS

The survival of FHF pigs was significantly increased by the treatment (58.9 +/- 21.8 hour) compared with the controls (22.3 +/- 8.1 hour). Mean blood ammonia levels and intracranial pressure during treatment were significantly lower compared with control groups.

CONCLUSION

Treatment of FHF pigs with the system significantly increased survival time, suggesting that this method may have applications as a clinical liver assist device.

Activation of complement components and reduced regulator expression in alcohol-induced liver injury in the rat

The purpose of this study was to evaluate the possible contribution of complement-mediated inflammation to the development of alcoholic liver disease. Male Wistar rats were fed ethanol by liquid diet in a model that results in continuous ethanol intoxication and induces early signs of alcoholic liver injury. After a six-week study period liver samples were analyzed for the deposition of complement components (C1, C3, and C8) and expression of cell membrane-bound regulators (Crry and CD59). Activation of the homologous complement system in vitro was tested by treating frozen liver sections with normal rat serum (NRS). Immunohistochemical analysis showed deposits of C8 in the liver sections of ethanol-treated rats. When frozen liver sections from these rats were treated with NRS, periportal deposition of both C3 and C8, but only slight C1 deposition, was observed. Immunohistochemical and Western blot analysis both revealed a reduced expression of the complement regulators Crry and CD59. These results suggest an induction of complement-activating capacity in the liver after chronic ethanol treatment. Lack of C1 deposition in the lesions suggests that complement activation occurs primarily via the alternative pathway. The reduced expression of the critical complement regulatory proteins Crry and CD59 may sensitize the liver to complement-mediated damage.

Prospects for the temporary treatment of acute liver failure

At present, the most successful treatment of acute liver failure is orthotopic liver transplantation, with survival rates ranging from 70% to 85%. However, mortality rates for liver failure remain high because of the shortage of available donor organs. Therefore, there has been renewed interest in temporary treatment methods for patients with acute liver failure to either allow liver regeneration or await liver transplantation. It is thought that the function of the liver can only be replaced with the biological substrate, e.g. liver cells or a whole liver specimen, which requires the availability of liver tissue from xenogeneic or human sources. In this review, existing temporary liver support techniques are summarized and the potential hazards are described. These include the immunological implications of these techniques, e.g. the host versus graft reaction, which may influence the effectivity of the support system, and in the long run may sensitize the patient to subsequent allogeneic transplantation. The graft versus host reaction is also considered. At present, one of the major concerns is the threat of pig-to-human transmission of activated endogenous retrovirus present in the pig genome. An overview is given of literature concerning the transmission of retrovirus particles in vitro and in vivo. Finally, new solutions for the development of ex vivo systems for temporary treatment of patients with acute liver failure are discussed. These include the use of new immortalized human cell lines and human fetal hepatocytes, and the possibility of isolating, expanding and genetically manipulating stem cells in order to have stable differentiated and committed cells.

Rejection of pig liver xenografts in patients with liver failure: implications for xenotransplantation

The pathophysiological state of rejection in liver xenotransplantation is poorly understood. Data from clinical pig liver perfusion suggest that pig livers might be rejected less vigorously than pig hearts or kidneys. Pig livers used in clinical xenoperfusions were exposed to blood from patients with liver failure. We have shown in an animal model that transplant recipients with liver failure are less capable of initiating hyperacute rejection of a xenografted liver than a healthy transplant recipient. The goal of this report is to examine the pathological characteristics of pig livers used in 2 clinical pig liver perfusions and combine this information with in vitro studies of pig-to-human liver xenotransplantation to determine whether the findings in the perfused pig livers could be explained in part by the diminished capacity of the patient with liver failure to respond to xenogeneic tissue. Pathological analysis of the perfused pig livers showed immunoglobulin M deposition in the sinusoids with little evidence of complement activation. Our in vitro studies showed that serum from patients with liver failure caused less injury to pig liver endothelium than serum from healthy subjects. Serum from patients with liver failure had similar levels of xenoreactive antibodies as serum from healthy humans. Incubation of serum from patients with liver failure with pig hepatic endothelial cells generated less iC3b, Bb fragment, and C5b-9 than serum from healthy subjects. We conclude that the altered injury in the perfused pig livers can be attributed to the relative complement deficiency that accompanies liver failure.

Extracorporeal perfusion for the treatment of acute liver failure

OBJECTIVE AND SUMMARY BACKGROUND DATA

Because of the shortage of available donor organs, death rates from liver failure remain high. Therefore, several temporary liver-assisting therapies have been developed. This article reviews various approaches to temporary liver support as well as immunologic and metabolic developments toward a solution for this problem.

METHODS

A literature review was performed using Medline and additional library searches to obtain further references. Only articles with a well-defined aim of study and methodology and a clear description of the outcome of the experiments were included.

CONCLUSIONS

Renewed interest has developed in old and new methods for an extracorporeal approach to the treatment of acute liver failure. Although temporary clinical improvement has been established, further research is needed to achieve a successful long-term clinical outcome. New developments in the field of genetic modification and tissue engineering await clinical application in the near future.

Complement profile in primary biliary cirrhosis

PBC is a chronic progressive liver disease of unknown etiology. Several abnormalities found in PBC support the hypothesis that it may be considered an autoimmune disease. Despite the complex and interesting relationship that exists between autoimmune disorders and the complement system, very few reports on the level of the serum complement component in PBC have been published, and most of these comprised only a few patients or analyzed only a scant number of the complement components. In the present study, sera of 73 PBC patients were analyzed for the levels of 10 complement components. It was found that the levels of most of the serum complement components, including C1q, C2, C3, C5, C7, properdin and factor B were significantly elevated in patients with PBC in comparison to healthy controls. The level of C4 was slightly lower than that of the normal controls (p = 0.019), while the levels of C6 and C8 were within the normal range. The number of PBC patients with serum levels of C4 and C6 < 60% of normal pooled serum was higher than in the respective control groups (6/69 compared with 0/26 and 4/71 compared with 0/27, respectively). However, the difference was not statistically significant. Thus, our study shows alterations in the levels of most complement components in PBC, the reasons for which are discussed.

Low serum levels of alpha-interferon, gamma-interferon, and interleukin-2 in alcoholic cirrhosis

The existence of cellular immune deficit in alcoholic cirrhosis, together with the role of alpha- and gamma-interferon and interleukin-2 in the immune system, led us to compare serum levels of these immune system mediators in a group of 40 patients with alcoholic cirrhosis classified according to Child-Pugh's grade of severity of liver disease and 23 healthy volunteers. Serum levels of alpha-IFN, gamma-IFN, and IL-2 were significantly depressed in alcoholic cirrhotics, with no significant differences between the different degrees of hepatic damage. The results suggest a profound alteration in the immune system of alcoholic cirrhotics, which may contribute to the development of the disease and the accompanying immune system deficit.

Infectious diseases associated with complement deficiencies

The complement system consists of both plasma and membrane proteins. The former influence the inflammatory response, immune modulation, and host defense. The latter are complement receptors, which mediate the cellular effects of complement activation, and regulatory proteins, which protect host cells from complement-mediated injury. Complement activation occurs via either the classical or the alternative pathway, which converge at the level of C3 and share a sequence of terminal components. Four aspects of the complement cascade are critical to its function and regulation: (i) activation of the classical pathway, (ii) activation of the alternative pathway, (iii) C3 convertase formation and C3 deposition, and (iv) membrane attack complex assembly and insertion. In general, mechanisms evolved by pathogenic microbes to resist the effects of complement are targeted to these four steps. Because individual complement proteins subserve unique functional activities and are activated in a sequential manner, complement deficiency states are associated with predictable defects in complement-dependent functions. These deficiency states can be grouped by which of the above four mechanisms they disrupt. They are distinguished by unique epidemiologic, clinical, and microbiologic features and are most prevalent in patients with certain rheumatologic and infectious diseases. Ethnic background and the incidence of infection are important cofactors determining this prevalence. Although complement undoubtedly plays a role in host defense against many microbial pathogens, it appears most important in protection against encapsulated bacteria, especially Neisseria meningitidis but also Streptococcus pneumoniae, Haemophilus influenzae, and, to a lesser extent, Neisseria gonorrhoeae. The availability of effective polysaccharide vaccines and antibiotics provides an immunologic and chemotherapeutic rationale for preventing and treating infection in patients with these deficiencies.