Opioid peptides and primary biliary cirrhosis

Liver transplantation in PBC and PSC: indications and disease recurrence

Primary biliary cirrhosis (PBC) and primary sclerosing cholangitis (PSC) represent major indications for liver transplantation (LT). Despite the steady increase in the incidence and prevalence of PBC, the number of liver transplants for PBC has fallen in recent years, whereas the number of transplants for PSC has remained stable. Indications for LT for PBC and PSC are no different from those of other causes of chronic liver disease, apart from some disease-specific indications. PBC and PSC have more favourable outcomes after LT, compared to viral hepatitis and alcohol-associated liver disease. Numerous studies have clearly demonstrated that PBC and PSC recur after LT. The diagnosis of recurrent disease should be made on agreed criteria. The impact of recurrent disease on survival is unclear. Study of recurrent PBC and PSC may provide a better understanding of the mechanisms of these diseases in the native liver.

Pathophysiology and current management of pruritus in liver disease

Pruritus is frequently reported by patients with cholestatic hepatobiliary diseases such as primary biliary cirrhosis, primary sclerosing cholangitis, intrahepatic cholestasis of pregnancy and hereditary cholestatic syndromes, but may accompany almost any other liver disease. Increased concentrations of bile salts, histamine, progesterone metabolites or endogenous opioids have been controversially discussed as potential pruritogens in cholestasis in the past. Most recently, novel insights unravelled lysophosphatidic acid (LPA), a potent neuronal activator, as a potential pruritogen in pruritus of cholestasis. Nevertheless, the pathogenesis of pruritus in cholestasis is still not clearly defined and current antipruritic treatment strategies provide relief only in a part of the affected patients. Based on recent experimental and clinical findings, this review outlines the actual insight in pathogenesis of pruritus in cholestasis and summarizes evidence-based and experimental therapeutic interventions for cholestatic patients suffering from itch.

Two histamine H2 receptor antagonists, zolantidine and cimetidine, modulate nociception in cholestatic rats

Cholestasis is associated with analgesia. The histamine H(2) receptors control pain perception. The involvement of histamine H(2) receptors on modulation of nociception in a model of elevated endogenous opioid tone, cholestasis, was investigated in this study using zolantidine and cimetidine as two H(2) receptor antagonists and dimaprit as a selective H(2) receptor agonist. Cholestasis was induced by ligation of the main bile duct using two ligatures and transsection of the duct at the midpoint between them. A significant increase in tail-flick latencies was observed in cholestatic rats compared to non-cholestatic rats. Administration of zolantidine (10, 20 and 40 mg/kg) and cimetidine (25, 50 and 100 mg/kg) in the cholestatic group significantly increased tail-flick latencies while dimaprit (10 and 20 mg/kg) injection in the cholestatic group decreased tail-flick latencies compared to the saline treated cholestatic group. Antinociception produced by injection of zolantidine and cimetidine in cholestatic rats was attenuated by co-administration of naloxone. Drug injection in non-cholestatic rats did not alter tail-flick latencies compared to the saline treated rats at any of the doses. At the doses used here, none of the drugs impaired motor coordination as revealed by the rota rod test. These data show that the histamine H(2) receptor system may be involved in the regulation of nociception during cholestasis. According to the hypothesis that increasing the nociception threshold in cholestasis may lead to a decrease in the perception of pruritus, the provision of the drugs that increase the threshold to nociception may be a novel approach to the treatment of cholestatic pruritus.

Naloxone in the management of hepatic encephalopathy

BACKGROUND/AIM

This study aimed to assess the effectiveness and safety of naloxone in the management of hepatic encephalopathy (HE).

METHODS

Cochrane collaboration methodology was used in a meta-analysis of randomized controlled trials of naloxone therapy for HE.

RESULTS

Seventeen randomized trials were identified with 15 studies involving 1054 patients meeting criteria for inclusion. Naloxone use was associated with a significant improvement in HE [relative risk (RR) 1.46; 95% confidence interval (CI) 1.27-1.67; P = 0.0005]. This comparison showed statistical heterogeneity (P < 0.10, and χ2 = 44.93). Subgroup analysis indicated naloxone administered parenterally by intermittent or continuous infusions to be effective (RR 1.34; 95% CI 1.17-1.53; P < 0.0001). A significant in trials by infusion route (RR 1.42; 95% CI 1.19-1.69; P < 0.0001) interaction was observed.

CONCLUSIONS

Naloxone may improve HE. However, published data are limited.

Innovative management of pruritus

Pruritus remains a significant problem facing dermatologists and can be associated with various dermatoses and systemic derangements. At times, one can treat the underlying cutaneous or systemic process to alleviate itch. However, it is frequently challenging to identify the cause of a patient's itch and, in this situation, even more difficult to manage the symptom effectively. In this article, the authors discuss the approach to a patient with generalized pruritus without clinically obvious dermatoses. They also addresses mechanisms and management modalities of itch in common systemic diseases, including cholestasis, uremia, and neuropathic dysfunction.

The relationship between inhalational anesthetic requirements and the severity of liver disease in liver transplant recipients according to three phases of liver transplantation

PURPOSE

Orthotopic liver transplantation (OLT) patients are known to show decreased intraoperative anesthetic requirements compared with patients undergoing other liver surgeries. The aim of this study was to determine the relationship between inhalational anesthetic requirements and the severity of liver disease among OLT patients.

METHODS

Fifty patients undergoing first living donor OLT were divided into 2 groups: model for end-stage liver disease (MELD) score<20 (low-MELD group; n=25) versus, MELD score>or=20 (high-MELD group; n=25). Anesthesia was maintained with desflurane and inspired concentration was titrated to maintain the bispectral index between 40 and 50. Neither intraoperative opioid nor epidural or intrathecal analgesia was used. End-tidal desflurane concentration (ETdes) was measured every 5 minutes and averaged in 30-minute intervals. These values were divided into 3 phases: preanhepatic (P 0.5 hour, P 1 hour, and P 1.5 hours), anhepatic (A 0.5 hour, A 1 hour, A 1.5 hours, and A 2 hours), and postreperfusion (R 0.5 hour, R 1 hour, R 1.5 hours, R 2 hours, R 2.5 hours, and R 3 hours). Results were compared between the 2 groups.

RESULTS

The demographic and intraoperative data were similar between the 2 groups. ETdes to maintain comparable anesthetic depth was significantly lower during the preanhepatic and anhepatic phases in the high-MELD than the low-MELD group, but there was no significant difference during the postreperfusion period.

CONCLUSIONS

OLT patients with high MELD scores showed less inhalational anesthetic requirements during the preanhepatic and the anhepatic periods than those with low MELD scores.

Fatigue in primary biliary cirrhosis

Primary biliary cirrhosis (PBC) is a chronic, autoimmune, cholestatic liver disease with a slowly progressive course. Without treatment, most patients eventually develop fibrosis of the liver and may need liver transplantation in the late stage of disease. Fatigue and pruritus are the most common symptoms of PBC, but the majority of patients are asymptomatic at first presentation. There is no specific treatment for fatigue in PBC, but modafinil has shown some potential beneficial effects, such as increased energy levels and decreased total sleep time. This Review article discusses the natural history and the measurement of fatigue in patients with PBC. The central and the peripheral mechanisms that have been suggested for the pathogenesis of fatigue in PBC are also discussed and treatment options are reviewed.

Antipruritic treatment with systemic μ-opioid receptor antagonists: a review

During the past two decades, systemic μ-opioid receptor antagonists (MORA) have been used in the treatment of various forms of chronic pruritus. In a number of case reports, case series, and controlled trials, treatment with MORA has demonstrated considerable antipruritic effects. In double-blind controlled studies, significant antipruritic relief has been achieved by MORA in cholestatic pruritus, chronic urticaria, and atopic dermatitis. In case reports and case series, antipruritic efficacy of MORA has been reported in prurigo nodularis, mycosis fungoides, postburn pruritus, aquagenic pruritus, hydroxyethyl starch-induced pruritus, and pruritus of unknown origin. However, most of the evidence remains anecdotal, the design of these trials varies, and comparison of results is difficult. In this review we aim to present an overview of these reports and to assess the evidence for the antipruritic action of the drugs naloxone, nalmefene, and naltrexone, which are currently in use for the treatment of chronic pruritus of different origins. We will also evaluate recommendations for the use of MORA in daily medical practice.

Clinical implications of novel aspects of biliary pathophysiology

Cholangiocytes are the epithelial cells that line the biliary tree; they are the target of chronic diseases termed cholangiopathies, which represent a daily challenge for clinicians, since definitive medical treatments are not available yet. It is generally accepted that the progression of injury in the course of cholangiopathies, and promotion and progression of cholangiocarcinoma are at least in part due to the failure of the cholangiocytes' mechanisms of adaptation to injury. Recently, several studies on the pathophysiology of the biliary epithelium have shed some light on the mechanisms that govern cholangiocyte response to injury. These studies provide novel information to help interpret some of the clinical aspects of cholangiopathies and cholangiocarcinoma; the purpose of this review is thus to describe some of these novel findings, focusing on their significance from a clinical perspective.

[Pruritus associated with cholestasis]

Pruritus is commonly associated with cholestatic disorders and shows wide interindividual variability. The presence of skin lesions due to scratching and the application of a visual analogue scale are useful for clinical evaluation. Although the pathophysiology of this entity is not well understood, advances have recently been made in understanding of the pruritoceptive neural pathway, which shares certain similarities with the nociceptive pathway, although there are other distinguishing characteristics such as the action of a specific neurotransmitter, GPR, on the first synapsis at the posterior horn of the spinal cord. Amongst the modulator systems of the pruritoceptive pathway is the action of the endogenous opioids. An increase of these opioids in cholestatic situations is the most widely accepted hypothesis for pruritus in these patients. Some treatments have proven efficacy in randomized clinical trials in patients with cholestatic disorders, such as anion exchange resins, rifampicin, opioid antagonists and ursodeoxycholic acid; the latter is especially useful in intrahepatic cholestasis of pregnancy.

A potent and selective inhibitor of endocannabinoid uptake, UCM707, potentiates antinociception induced by cholestasis

Cholestasis is associated with changes including analgesia. The endocannabinoid system can reduce pain sensitivity. Considering the interaction between the endogenous opioid and endocannabinoid systems in nociception processing, we studied the effect of UCM707 as a potent and selective inhibitor of endocannabinoid uptake on modulation of nociception in a model of elevated endogenous opioid tone, cholestasis. Cholestasis was induced in male Sprague-Dawley rats by ligation of the main bile duct using two ligatures and transecting the duct at the midpoint between them. Seven days later, tail-flick latencies were measured 10 min after injection of UCM707 (0.1, 1 and 10 mg/kg, i.p.) alone or with co-administration of a CB(1) receptor antagonist, AM251 (1 mg/kg, i.p.), with UCM707 (10 mg/kg, i.p.) in experimental groups. A significant increase (P < 0.01) in tail-flick latency was observed in cholestatic rats compared with rats belonging to unoperated and sham groups. Administration of UCM707 (1 and 10 mg/kg) to cholestatic animals significantly increased tail-flick latency compared with the vehicle-treated cholestatic group (P < 0.05 and P < 0.001, respectively). UCM707 injection in unoperated and sham groups did not alter baseline tail-flick latency compared with vehicle-treated groups. The effect of UCM707 in the cholestatic group was blocked by co-administration of AM251 (1 mg/kg, i.p.) with UCM707. These data showed that the endocannabinoid system is involved in nociception processing during cholestasis and that the effects of UCM707 on the pain threshold in cholestatic rats may be a result of CB(1) receptor activation by the increased extracellular levels of endocannabinoids.

Management of autoimmune and cholestatic liver disorders

The management of autoimmune and cholestatic liver disorders is a challenging area of hepatology. Autoimmune and cholestatic liver diseases represent a comparatively small proportion of hepatobiliary disorders, yet their appropriate management is of critical importance for patient survival. In this article, management strategies are discussed, including the indications and expectations of pharmacologic therapy, endoscopic approaches, and the role of liver transplantation.

[Opioid-induced pruritus. Mechanisms and treatment regimens]

Substantial progress has been achieved in recent years in research on the interaction between pain and pruritus. Over and above the known inhibition of pruritus by painful stimuli (e.g. scratching), a foundation for the explanation of opioid-induced pruritus was laid through the discovery of pruritus-specific neuronal processing channels. Although traditionally the degranulating effect of opioids on mast cells was assumed to be the essential mechanism, it is now clear that opioids can also induce itching at the spinal level. Neurons of the dorsal horn of the pain system inhibit spinal itch neurons. If this inhibition is weakened by opioids, the disinhibited itch neurons become active and mediate itching, without stimulation of the primary afferent peripheral nerves. Spinal triggering of itching is observed in particular by activation of mu-opioid receptors (mu-OR), while kappa-OR surprisingly suppress itch. The therapeutic implications of this interaction will be described.

Pathogenesis and treatment of pruritus in cholestasis

Pruritus is an enigmatic, seriously disabling symptom accompanying cholestatic liver diseases and a broad range of other disorders. Most recently, novel itch-specific neuronal pathways, itch mediators and their relevant receptors have been identified. In addition, new antipruritic therapeutic strategies have been developed and/or are under evaluation. This review highlights recent experimental and clinical findings focusing on the pathogenesis and actual treatment of pruritus in cholestatic liver disease. Evidence-based therapeutic recommendations, including the use of anion exchange resins cholestyramine, colestipol and colesevelam, the microsomal enzyme inducer rifampicin, the opioid receptor antagonists naltrexone and naloxone, and the serotonin reuptake inhibitor sertraline, are provided.

Role of plasmapheresis in the treatment of severe pruritus in pregnant patients with primary biliary cirrhosis: case reports

BACKGROUND

Primary biliary cirrhosis (PBC) may be associated with pruritus and, when present, may be accentuated during pregnancy. Several therapeutic modalities have been used to control itching caused by cholestasis, with variable responses. Drug therapies are ill-advised, particularly in early pregnancy. Plasmapheresis has been successful in controlling pruritus in patients with cholestasis. The use of plasmapheresis to alleviate severe life-threatening pruritus during pregnancy is reported in two patients with PBC.

CASE PRESENTATIONS

Two patients with PBC presented during their second trimester of pregnancy with severe pruritus that did not respond to the anion exchange resin cholestyramine. Their symptoms were disabling to the point that one patient had suicidal ideation. Given the severity of their symptoms, multiple sessions of plasmapheresis were instituted with good control of pruritus. Both patients tolerated the procedure well and delivered healthy babies.

CONCLUSION

Plasmapheresis is a relatively safe and rapidly effective treatment for severe pruritus during pregnancy in patients with PBC.

Effect of metal chelating agents on pentylenetetrazole-induced seizure threshold in cholestatic mice

Zinc has been proven to be anticonvulsant in several studies which indicate that diphenylthiocarbazone (dithizone) and diethyldithiocarbamate (DEDTC), zinc chelating agents, enhance seizure activities. There is also evidence that nitric oxide (NO) generators increase zinc concentration in the brain. On the other hand, the increased level of NO in the nervous system and the consequently increased seizure threshold in cholestatic mice have been well studied. Thus, it could be hypothesized that one of the reasons for the increased seizure threshold in cholestasis is partly the enhanced endogenous zinc concentration, at least in part, due to the overproduction of NO. In this study, we examined the hypothesis that zinc chelating agents might decrease seizure activity to its pre-cholestatic level in bile duct-ligated (BDL) mice. Mice were intra-peritoneally injected with dithizone and diethyldithiocarbamate (DEDTC) before the induction of seizure by pentylenetetrazole (PTZ) and then the seizure activity was recorded. Dose response (dithizone: 5, 30, 100 and 200mg/kg; DEDTC: 25, 50 and 100mg/kg) and time course (only for dithizone: 15, 30, 60 and 120 min) studies were performed first. Then, the effects of cholestasis, with and without dithizone injection, on seizure activity were assessed. Proconvulsant effect of dithizone and DEDTC was proved to be dose dependent although time interval between dithizone and PTZ injections did not play any significant role in the seizure activity. Cholestasis decreased seizure activity and increased lag phase before seizure and both effects were decreased by dithizone injection. It is elicited that zinc may mediate the cholestasis-induced decrement in seizure activity.

Elevation of pentylenetetrazole-induced seizure threshold in cholestatic mice: interaction between opioid and cannabinoid systems

BACKGROUND AND AIM

Several studies have reported that endogenous opioid and cannabinoid systems may be involved in some pathophysiological changes occurring in cholestatic liver disease. It is well known that endogenous opioids and cannabinoids alter the susceptibility of experimental animals to different models of seizure.

METHODS

The alterations in pentylenetetrazole-induced clonic seizure thresholds were evaluated from 1 to 6 days after bile duct ligation in mice. Whether the pretreatment of cholestatic mice with different doses of opioid receptor antagonist naltrexone or cannabinoid CB(1) receptor antagonist AM251 (AM251) would have changed the clonic seizure threshold was also examined.

RESULTS

Although the clonic seizure threshold was similar between sham-operated and unoperated mice, there was a time-dependent increase in the threshold in cholestatic mice, reaching a peak on day 3 after bile duct ligation and declining partially after day 4. Chronic pretreatment with naltrexone (2, 5, and 10 mg/kg) reversed the increased threshold in cholestatic mice on day 3 after operation in a dose-dependent manner with the highest doses used restoring the threshold to that of the control animals. A similar reversal of the increased threshold was observed after acute (0.5, 0.75, and 1 mg/kg) or chronic (0.5 mg/kg for 4 days) pretreatment with AM251. Moreover, concurrent administration of doses of AM251 and naltrexone that each separately induced a partial reversal of increased seizure threshold in cholestasis caused a complete restoring of the threshold to the control level.

CONCLUSIONS

Both opioid and cannabinoid CB(1) receptors may be involved in the dramatic increase in pentylenetetrazole-induced seizure threshold in cholestasis.

Effects of URB597 as an inhibitor of fatty acid amide hydrolase on modulation of nociception in a rat model of cholestasis

Cholestasis is associated with increased activity of the endogenous opioid system that results in analgesia. Endocannabinoid system can reduce pain sensitivity. The use of inhibitors of endocannabinoid metabolism is a novel means of pharmacologically increasing endocannabinoid levels. Considering the interaction that has been shown between the endogenous opioid and endocannabinoid systems in nociception processing, we studied the effects of URB597, a selective inhibitor of FAAH (fatty acid amide hydrolase), on modulation of nociception in a model of elevated endogenous opioid tone, cholestasis. Cholestasis was induced by ligation of the main bile duct using two ligatures and then transection of the duct at the midpoint between them. Seven days after surgery, tail-flick latencies were measured at 60 min after drug administration. A significant increase (P<0.001) in nociception threshold was observed in cholestatic rats compared to unoperated and sham groups. Administration of URB597 (0.3 mg/kg, i.p.) in cholestatic animals significantly (P<0.001) increased tail-flick latency compared to the vehicle treated cholestatic group. URB597 injection to unoperated and sham groups caused a significant (P<0.05, P<0.05) increase in tail-flick latency compared to their respective vehicle treated groups. The antinociceptive effect of URB597 was blocked by coadministration of a cannabinoid CB(1) receptor antagonist, AM251 (1 mg/kg, i.p.) but not by a cannabinoid CB(2) receptor antagonist, SR144528 (1 mg/kg, i.p.) with URB597. These data showed that URB597 as a FAAH inhibitor potentiates antinociception induced by cholestasis in tail-flick test and that the inhibitory effects of URB597 in this model are mediated by cannabinoid CB(1) and not CB(2) receptors.

Clinical features and management of primary biliary cirrhosis

Primary biliary cirrhosis (PBC), which is characterized by progressive destruction of intrahepatic bile ducts, is not a rare disease since both prevalence and incidence are increasing during the last years mainly due to the improvement of case finding strategies. The prognosis of the disease has improved due to both the recognition of earlier and indolent cases, and to the wide use of ursodeoxycholic acid (UDCA). New indicators of prognosis are available that will be useful especially for the growing number of patients with less severe disease. Most patients are asymptomatic at presentation. Pruritus may represent the most distressing symptom and, when UDCA is ineffective, cholestyramine represents the mainstay of treatment. Complications of long-standing cholestasis may be clinically relevant only in very advanced stages. Available data on the effects of UDCA on clinically relevant end points clearly indicate that the drug is able to slow but not to halt the progression of the disease while, in advanced stages, the only therapeutic option remains liver transplantation.

Cholestatic hepatitis as a possible new side-effect of oxycodone: a case report

Introduction

Oxycodone is a widely-used semisynthetic opioid analgesic that has been used for over eighty years. Oxycodone is known to cause side effects such as nausea, pruritus, dizziness, constipation and somnolence. As far as we are aware cholestatic hepatitis as a result of oxycodone use has not been reported so far in the world literature.

Case presentation

A 34-year-old male presented with cholestatic jaundice and severe pruritus after receiving oxycodone for analgesia post-T11 vertebrectomy. Extensive laboratory investigations and imaging studies did not reveal any other obvious cause for his jaundice and a liver biopsy confirmed canalicular cholestatis suggestive of drug-induced hepatotoxicity. The patient's symptoms and transaminases normalised on withdrawal of oxycodone confirming that oxycodone was the probable cause of the patient's hepatotoxicity.

Conclusion

We conclude that cholestatic hepatitis is possibly a rare side effect of oxycodone use. Physicians should be aware of the possibility of this potentially serious picture of drug-induced hepatotoxicity.

Pruritus in primary biliary cirrhosis: pathogenesis and therapy

Pruritus is a symptom experienced by patients who have primary biliary cirrhosis. It seems to result from pruritogens that (as a result of cholestasis) accumulate in plasma and other tissues, and which lead to altered neurotrasnmission. Administration of medications that change opioid neurotransmission (ie, opiate antagonists) results in relief of pruritus and its behavioral manifestation, scratching. Through unknown mechanisms, other centrally acting medications, including antidepressants, may have ameliorating effects on the pruritus of cholestasis. Stimulating endogenous detoxification pathways in the liver may also lead to the amelioration of pruritus. The removal of pruritogens through administration of nonabsorbable resins, nasobiliary drainage, biliary diversion, plasmapheresis, and various dialysis procedures is reported to decrease pruritus in liver disease, although the substances that are presumably removed are unknown.

Wound healing and local neuroendocrine regulation in the injured liver

The hepatic wound-healing response is a complex process involving many different cell types and factors. It leads to the formation of excessive matrix and a fibrotic scar, which ultimately disrupts proper functioning of the liver and establishes cirrhosis. Activated hepatic myofibroblasts, which are derived from cells such as hepatic stellate cells (HSCs), play a key role in this process. Upon chronic liver injury, there is an upregulation in the local neuroendocrine system and it has recently been demonstrated that activated HSCs express specific receptors and respond to different components of this system. Neuroendocrine factors and their receptors participate in a complex network that modulates liver inflammation and wound healing, and controls the development and progression of liver fibrosis. The first part of this review provides an overview of the molecular mechanisms governing hepatic wound healing. In the second section, we explore important components of the hepatic neuroendocrine system and their recently highlighted roles in HSC biology and hepatic fibrogenesis. We discuss the therapeutic interventions that are being developed for use in antifibrotic therapy.

Update on the treatment of the pruritus of cholestasis

The pruritus of cholestasis is a difficult clinical problem to manage. It can be severe and interfere with sleep. Clinical behavioral studies have confirmed that the pruritus is mediated at least in part by endogenous opioids. Other neurotransmitter systems may be involved in the mediation of pruritus. Work continues to identify the mechanisms that mediate the pruritus and to develop specific drugs to treat this often maddening symptom.

Primary biliary cirrhosis

Primary biliary cirrhosis (PBC) is a chronic and slowly progressive cholestatic liver disease of autoimmune etiology characterized by injury of the intrahepatic bile ducts that may eventually lead to liver failure. Affected individuals are usually in their fifth to seventh decades of life at time of diagnosis, and 90% are women. Annual incidence is estimated between 0.7 and 49 cases per million-population and prevalence between 6.7 and 940 cases per million-population (depending on age and sex). The majority of patients are asymptomatic at diagnosis, however, some patients present with symptoms of fatigue and/or pruritus. Patients may even present with ascites, hepatic encephalopathy and/or esophageal variceal hemorrhage. PBC is associated with other autoimmune diseases such as Sjogren's syndrome, scleroderma, Raynaud's phenomenon and CREST syndrome and is regarded as an organ specific autoimmune disease. Genetic susceptibility as a predisposing factor for PBC has been suggested. Environmental factors may have potential causative role (infection, chemicals, smoking). Diagnosis is based on a combination of clinical features, abnormal liver biochemical pattern in a cholestatic picture persisting for more than six months and presence of detectable antimitochondrial antibodies (AMA) in serum. All AMA negative patients with cholestatic liver disease should be carefully evaluated with cholangiography and liver biopsy. Ursodeoxycholic acid (UDCA) is the only currently known medication that can slow the disease progression. Patients, particularly those who start UDCA treatment at early-stage disease and who respond in terms of improvement of the liver biochemistry, have a good prognosis. Liver transplantation is usually an option for patients with liver failure and the outcome is 70% survival at 7 years. Recently, animal models have been discovered that may provide a new insight into the pathogenesis of this disease and facilitate appreciation for novel treatment in PBC.

Cholestasis and endogenous opioids: liver disease and exogenous opioid pharmacokinetics

A class of endogenous opioids is upregulated in liver disease particular to cholestasis, which contributes to symptoms in liver disease such as pruritus, hypotension and encephalopathy. Symptoms associated with cholestasis are reversed or at least ameliorated by mu opioid receptor antagonists. Palliation of symptoms related to cholestatic liver disease also involves bile acid binding agents. Opioid receptor antagonists, unlike bile acid binding agents, have been reported to relieve multiple symptoms, except for pruritus, and improve liver function as demonstrated in experimental cholestasis. Exogenous opioid pharmacology is altered by liver disease. Dose reduction or prolongation of dose intervals is necessary depending on the severity of liver disease.

The efficacy and safety of bile Acid binding agents, opioid antagonists, or rifampin in the treatment of cholestasis-associated pruritus

OBJECTIVES

The objective of this review was to evaluate the efficacy and safety of rifampin, opioid antagonists, or bile acid binding agents in the treatment of cholestasis-related pruritus (CAP) from available randomized controlled trial evidence.

METHODS

In addition to a comprehensive gray literature search, the Cochrane Library, MEDLINE, EMBASE, PubMed, and Web of Science were searched. Only full-text RCTs in participants (>75% adult) with CAP on at least one of the three medications were included. The primary outcome was change in pruritus score, recorded as a continuous or dichotomous outcome. Two independent reviewers performed trial selection and quality assessment.

RESULTS

From 487 citations, 12 RCTs were included. Rifampin (standardized mean difference [SMD]-1.62, 95% CI -3.05 to -0.18) and opioid antagonists (SMD -0.68, 95% CI -1.19 to -0.17) significantly reduced CAP. The two cholestyramine studies were too heterogeneous to pool. Although cholestyramine (P= 0.35) and rifampin (P= 0.96) were not associated with greater side effects compared with placebo, opioid antagonists were (number needed to harm = 2.6, 95% CI 1.4-25).

CONCLUSIONS

The available RCTs are small, few in number, and use varying scales for measuring pruritus. Although both opioid antagonists and rifampin demonstrated a reduction in pruritus, there were insufficient data to judge the efficacy of cholestyramine. Opioid antagonists were associated with transient side effects in a significant proportion of patients. A longer well-designed randomized controlled trial is needed to confirm the efficacy of bile acid binding agents and accurately assess adverse events.

micro-Opioid receptor activation prevents acute hepatic inflammation and cell death

BACKGROUND AND AIMS

The detrimental impact of opioid agonist on the clinical management of inflammatory diseases remains elusive. Given the anti-inflammatory properties of the mu-opioid receptor (MOR) agonists at the intestinal barrier, we hypothesised that MOR activation might also dampen acute hepatic inflammation and cell death-major determinants in the pathogenesis of liver diseases.

PATIENTS AND METHODS

The expression of MOR in liver biopsy specimens and peripheral blood mononuclear cells of untreated patients with chronic hepatitis C virus infection and controls, primary hepatocytes and cell lines was determined by quantitative PCR, immunoblotting and/or immunohistochemistry. The effects of peripheral MOR agonist (d-Ala2,NMe-Phe4,Gly5-ol (DAMGO)) and/or antagonist (naloxone methiodide) were explored in two models of acute hepatitis in mice. MOR-deficient mice were used to evaluate the essential regulatory role of MOR during carbon tetrachloride (CCl(4))-induced hepatitis. The role of DAMGO in cell death was investigated using terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling (TUNEL) analysis and quantification of lactate dehydrogenase release.

RESULTS

The key role of MOR in the prevention of acute hepatic inflammation and cell death in vivo and in vitro is reported. Whereas MOR gene expression increased transiently in the model of acute liver injury and TNFalpha-treated HepG2 cells, an impaired expression of MOR mRNA in human chronic hepatitis C samples was found. Furthermore, preventive administration of the selective MOR agonist DAMGO enhanced hepatoprotective-signalling pathways in vivo that were blocked by using naloxone methiodide. Consistently, genetic and pharmacological inhibition of MOR enhanced the severity associated with experimental hepatotoxin-induced hepatitis. Finally, treatment with DAMGO was shown to prevent cell death in vitro in HepG2 cells in a MOR-dependent manner and to prevent concanavalin A- and CCl(4)-induced cell death in vivo, providing a possible explanation for the anti-inflammatory role of MOR activation in the liver.

CONCLUSIONS

The results indicate that MOR agonists may prevent acute hepatitis and hold promising therapeutic use to maintain remission in both chronic inflammatory bowel and liver diseases.

Treatment of cholestatic pruritus in children

PURPOSE

The treatment of cholestatic pruritus in children is reviewed.

SUMMARY

Cholestasis is characterized by an accumulation of substances that are normally secreted in the bile. Pruritus is a well-known feature of chronic cholestasis in both adults and children and has been reported as the most incapacitating symptom in children with chronic liver disease. Traditional agents, such as antihistamines, are typically ineffective as monotherapy in controlling cholestatic pruritus. As a result, clinicians have looked to other agents, such as rifampin, phenobarbital, ursodiol, opioid antagonists, and bile-binding resins, for attaining better control of pruritic symptoms. Each agent demonstrates different levels of efficacy in pediatric and adult literature. There are no guidelines or algorithms to guide therapy with these agents for children. As a result, an agent should be selected based on the patient's concurrent diseases and current medication regimen. Cholestyramine and ursodiol are both safe and inexpensive, with documented efficacy for cholestatic pruritus in children. Because cholestatic pruritus is likely a result of multiple mechanisms, combination therapy with agents that have differing mechanisms of action might be beneficial and could capitalize on potential synergy between the agents used. Future therapy for cholestatic pruritus may include serotonin antagonists, selective serotonin-reuptake inhibitors, and leukotriene antagonists.

CONCLUSION

Depending on the underlying disease state resulting in cholestasis, phenobarbital, ursodiol, bile sequestering agents, and opioid antagonists appear to be most effective for treating pruritus related to intrahepatic cholestasis. Alternatively, rifampin appears to be the only agent with reported treatment efficacy for pruritus related to extrahepatic cholestasis.

Naltrexone, an opioid receptor antagonist, attenuates liver fibrosis in bile duct ligated rats

AIM

The aim of this study was to investigate the hypothesis that the opioid system is involved in the development of hepatic fibrosis.

METHODS

The effect of naltrexone (an opioid receptor antagonist) on hepatic fibrosis in bile duct ligated (BDL) or sham rats was assessed by histology and hepatic hydroxyproline levels. Liver matrix metalloproteinase 2 (MMP-2) was measured by zymography, and alpha smooth muscle actin (alpha-SMA) and CD45 (leucocyte common antigen) by immunohistochemistry. The redox state of the liver was assessed by hepatic glutathione (GSH)/oxidised glutathione (GSSG) and S-nitrosothiol levels. Subtypes of opioid receptors in cultured hepatic stellate cells (HSCs) were characterised by reverse transcriptase-polymerase chain reaction, and the effects of selective delta opioid receptor agonists on cellular proliferation, tissue inhibitor of metalloproteinase 1 (TIMP-1), and procollagen I expression in HSCs determined.

RESULTS

Naltrexone markedly attenuated the development of hepatic fibrosis as well as MMP-2 activity (p<0.01), and decreased the number of activated HSCs in BDL rats (p<0.05). The development of biliary cirrhosis altered the redox state with a decreased hepatic GSH/GSSG ratio and increased concentrations of hepatic S-nitrosothiols, which were partially or completely normalised by treatment with naltrexone, respectively. Activated rat HSCs exhibited expression of delta1 receptors, with increased procollagen I expression, and increased TIMP-1 expression in response to delta(1) and delta(2) agonists, respectively.

CONCLUSIONS

This is the first study to demonstrate that administration of an opioid antagonist prevents the development of hepatic fibrosis in cirrhosis. Opioids can influence liver fibrogenesis directly via the effect on HSCs and regulation of the redox sensitive mechanisms in the liver.

Modulation of cholestasis-induced antinociception in rats by two NMDA receptor antagonists: MK-801 and magnesium sulfate

Acute cholestasis is associated with increased activity of the endogenous opioid system that results to changes including analgesia. N-methyl-d-aspartate (NMDA) receptors are involved in the nociceptive pathway and play a major role in the development of morphine induced analgesia. The magnesium acts as a non-competitive NMDA receptor antagonist by blocking the NMDA receptor channel. Considering the reported antinociceptive effect of magnesium sulfate as a NMDA receptor antagonist and the existence of close functional links between NMDA receptor antagonists and magnesium with the opioid system, we studied the effect of acute and chronic administration of MK-801 as a NMDA antagonist and magnesium sulfate on modulation of nociception in an experimental model of elevated endogenous opioid tone, acute cholestasis, using the tail-flick paradigm. Cholestasis was induced by ligation of the main bile duct using two ligatures and then transsection of the duct at the midpoint between them. A significant increase (P<0.001) in nociception threshold was observed in bile duct ligated rats compared to unoperated and sham-operated animals. In acute treatment, MK-801 (0.1 mg/kg, b.i.d), but not magnesium (150 mg/kg magnesium sulfate, i.e. 30 mg/kg of Mg(+2), i.p., b.i.d.) increased antinociception in cholestatic rats compared to saline treated cholestatics (P<0.05). In chronic treatment, administration of MK-801 or magnesium sulfate for 7 consecutive days, increased tail-flick latency (P<0.05, P<0.01) in cholestatic animals compared to saline treated cholestatics. These data showed that NMDA receptor pathway is involved in modulation of cholestasis-induced antinociception in rats and that repeated dosages of magnesium sulfate similar to MK-801 is able to modulate nociception in cholestasis.

Resolving fibrosis in the diseased liver: translating the scientific promise to the clinic

Liver fibrosis and its end-stage disease cirrhosis are a major cause of mortality and morbidity throughout the world. Fibrosis is a response to chronic liver injury or infection that if unabated leads to the replacement of normal functional liver tissue with scar tissue. Basic research over the past decade has generated a vastly improved knowledge of the cell and molecular biology of liver fibrosis that provides a framework on which to design and develop therapeutics. The field has also witnessed a genuine paradigm shift from the original dogma that liver fibrosis is only ever a progressive process, to the new understanding that liver fibrosis even in an advanced stage can be reversible. There is therefore renewed optimism that liver fibrosis may be cured providing that we develop therapies that halt the fibrogenic process and encourage the natural regenerative properties of the liver. The key to the design of effective therapeutics will be to exploit the ongoing discoveries pertaining to the biology and function of fibrogenic hepatic myofibroblasts and their interplay with other liver cells and with the hepatic extracellular matrix. This review provides a critique of those discoveries in basic research that provide the most promise for translation to the clinic. In addition, we review the latest developments in the search for minimal invasive diagnostic tests for fibrosis that will be essential for determining the efficacy of anti-fibrotic drugs.

Rifampin is safe for treatment of pruritus due to chronic cholestasis: a meta-analysis of prospective randomized-controlled trials

OBJECTIVES

To determine the safety and efficacy of rifampin for treatment of pruritus associated with cholestasis due to chronic liver disease.

METHODS

Medical literature was searched systematically using keywords as rifampicin, rifampin, rifamycin, cholestasis, pruritus, itching, and liver disease. Trials that compared the efficacy of rifampin with placebo/alternative for treatment of pruritus due to chronic cholestasis were selected for analysis. Primary outcomes were resolution of pruritus and development of side effects. Association was measured with the odds ratio (OR). Breslow-Day method was used to treat for homogeneity under null hypothesis that OR was consistent across all the trials. Corrected Mantel-Haenszel chi(2) test was used to test if OR differed systematically from value of 1.

RESULTS

Five prospective randomized-controlled cross-over trials with 61 patients were identified. Treatment with rifampin led to complete or partial resolution of pruritus in 47 (77%) patients as compared with 12(20%) treated with placebo or alternative (OR 15.2, 95% confidence interval 5.2-45.6, P=0.001). Four (7%) patients treated with rifampin suffered side effects, which resolved after its discontinuation. There was no incidence of hepatotoxicity. Test of heterogeneity for primary end points among the trials was not significant (P=0.16).

CONCLUSION

This meta-analysis suggests that rifampin is safe and effective for treatment of pruritus due to chronic cholestasis. This analysis also suggests that use of rifampin for short duration is associated with a low risk of hepatotoxicity.

Involvement of nitrergic and opioidergic systems in the hypothermia induced by cholestasis in rats

BACKGROUND AND AIM

Cholestatic animals display abnormal hypothalamic responses to pyrogenic stimuli and decreased febrile response to lipopolysaccharide. The present study was undertaken to determine if obstructive cholestasis was associated with abnormal thermoregulation under thermoneutral conditions.

METHODS

Male Sprague-Dawley rats weighing 200-250g were randomly divided into 21 groups. Three sets of seven groups were unoperated control, sham-operated and bile duct-ligated rats. The groups of unoperated control, sham-operated and bile duct-ligated rats were treated with daily administration of isotonic saline solution, N(omega)-nitro-l-arginine methyl ester (l-NAME) (3, 10, or 20mg/kg), naltrexone (10 or 20mg/kg) or aminoguanidine (150mg/kg). Body temperatures were measured before and 1, 3, 5 and 7 days after the surgery.

RESULTS

Bile duct-ligated rats had lower body temperature than sham-operated animals at 3 (P<0.001) and 5 (P<0.01) days after surgery. l-NAME, a non-selective inhibitor of nitric oxide synthase (NOS) (10, 20mg/kg, i.p.) or aminoguanidine, a selective iNOS inhibitor (150mg/kg, i.p.), completely reversed this hypothermia (P>0.05). Naltrexone, a non-selective opioid antagonist (20mg/kg, i.p.), also completely corrected this hypothermia (P>0.05). There was a drop in temperature in the first day after the surgery in sham and BDL groups compared to unoperated controls, which was significant in some groups demonstrating the effect of surgery and anesthetic drugs on the body temperature.

CONCLUSIONS

Cholestatic rats show impaired thermoregulation suggesting the involvement of nitrergic and opioidergic systems.

Endogenous opioids modulate the growth of the biliary tree in the course of cholestasis

BACKGROUND & AIMS

There is poor knowledge on the factors that modulate the growth of cholangiocytes, the epithelial cell target of cholangiopathies, which are diseases leading to progressive loss of bile ducts and liver failure. Endogenous opioids are known to modulate cell growth. In the course of cholestasis, the opioidergic system is hyperactive, and in cholangiocytes a higher expression of opioid peptide messenger RNA has been described. This study aimed to verify if such events affect the cholangiocyte proliferative response to cholestasis.

METHODS

The presence of the delta opioid receptor (OR), muOR, and kappaOR was evaluated. The effects on cholangiocyte proliferation of the in vitro and in vivo exposure to their selective agonists, together with the intracellular signals, were then studied. The effects of the OR antagonist naloxone on cell growth were also tested both in vivo and in vitro.

RESULTS

Cholangiocytes express all 3 receptors studied. deltaOR activation strongly diminished the proliferative and functional response of cholangiocytes to cholestasis, whereas muOR resulted in a slight increase in cell growth. The deltaOR signal is mediated by the IP3/CamKIIalpha/PKCalpha pathway, which inhibits the cAMP/PKA/ERK1/2/AKT cascade. In contrast, muOR activation stimulates the cAMP/PKA/ERK1/2/AKT cascade but does not affect the IP3/CamKIIalpha/PKCalpha pathway. The blockage of endogenous opioid peptides by naloxone further enhanced cholangiocyte growth both in vivo and in vitro.

CONCLUSIONS

The increase in opioid peptide synthesis in the course of cholestasis aims to limit the excessive growth of the biliary tree in the course of cholestasis by the interaction with the deltaOR expressed by cholangiocytes.

Alteration in specific opioid-receptor labeling on peripheral blood leukocytes of bile duct-ligated rat

Cholestasis is associated with increased tonus and activity of opioidergic system. Opioid peptides have also immunomodulatory effects through stimulation of specific opioid receptors on the immune cells, or in an indirect fashion via the central nervous system. The combination of immunofluorescent technique and flow cytometry has proven to be sensitive method for the detection of leukocyte opioid receptors. This study was designed to examine the effect of cholestasis on the opioid-receptor labeling on the leukocytes from bile duct-ligated rats. Seven days after surgery, leukocytes were isolated from the peripheral blood of bile duct-ligated or sham-operated rats. The cells were incubated with naltrexone-fluorescein, in the absence or presence of unlabeled naltrexone, as a competitor and analysed by flow cytometry. Monocytes and granulocytes from bile duct-ligated rats showed an increase in the percentage of opioid-receptor labeling (29.6+/-2.08 for cholestatic versus 23+/-1.9 for sham, p<0.001; 50.6+/-3.18 for cholestatic versus 39.6+/-1.7 for sham, p<0.05; respectively). Furthermore, there was a decrease in the expression of opioid receptors on leukocytes due to cholestasis. In conclusion, changes in specific opioid-receptor labeling and percent of labeled leukocytes indicate that endogenous opioid-receptor interaction may be altered in peripheral blood leukocytes in acute cholestasis.

Extrahepatic manifestations of cholestatic liver diseases: pathogenesis and therapy

Pruritus, fatigue, and metabolic bone disease are frequent complications of cholestatic liver diseases, which can be quite distressing for the patient and can considerably reduce the quality of life. The molecular pathogenesis of these extrahepatic manifestations of cholestasis is poorly understood, and hypotheses to explain these symptoms are being discussed. This article provides treatment recommendations for the complications of cholestasis based on putative pathomechanisms and summarizes recent experimental and clinical data involving management options.

Extrahepatic manifestations of cholestatic liver diseases: pathogenesis and therapy

Pruritus, fatigue, and metabolic bone disease are frequent complications of cholestatic liver diseases, which can be quite distressing for the patient and can considerably reduce the quality of life. The molecular pathogenesis of these extrahepatic manifestations of cholestasis is poorly understood, and hypotheses to explain these symptoms are being discussed. This article provides treatment recommendations for the complications of cholestasis based on putative pathomechanisms and summarizes recent experimental and clinical data involving management options.

Palliative care for patients with end-stage liver disease ineligible for liver transplantation

The proportion of patients with ESLD who will be managed without liver transplantation will increase in the near future, largely as a result of the increasing age of the population. Patients with ESLD are subject to many physical and psychosocial symptoms that negatively affect health-related quality of life. Sleep quality should be maximized by controlling pruritus and leg cramps. Many frequently used therapies are not supported by a strong evidence base. Advance directives should be addressed with all patients with ESLD, preferably in the outpatient setting before an acute deterioration. Medicare provides a hospice benefit for patients with ESLD, and referral to a hospice is appropriate for patients with an expected survival of 6 months or less.

Medical palliation of the jaundiced patient with pruritus

Cholestasis secondary to infiltration of the liver by malignant tumors or by obstruction of the biliary tree can be complicated by pruritus. The clinician and ancillary personal must recognize how debilitating pruritus is and identify the treatment of this symptom as a priority. Because robust clinical trials have not been conducted in patients who have pruritus with cholestasis, a network connecting the services that provide care for these patients (eg, hospices) may be useful for disseminating information.

Effect of oral naltrexone on pruritus in cholestatic patients

AIM

To determine the efficacy and potential complications of oral naltrexone used in the treatment of pruritus in cholestatic patients and to compare them with other studies.

METHODS

Thirty-four enrolled cholestatic patients complaining of pruritus were studied. In the initial phase, pruritus scores during day and night were evaluated. Subsequently, patients were given a placebo for one week followed by naltrexone for one week. In each therapeutic course (placebo or naltrexone) day and night pruritus scores were distinguished by a visual analogue scale (VAS) system and recorded in patients' questionnaires.

RESULTS

Both naltrexone and placebo decreased VAS scores significantly. Naltrexone was more effective than placebo in decreasing VAS scores. Both day and night scores of pruritus decreased by half of the value prior to therapy in thirteen patients (38%). Daytime pruritus improved completely in two patients (5.9%), but no improvement in the nighttime values was observed in any patient. Sixteen patients (47%) suffered from naltrexone complications, eleven (32%) of them were related to its withdrawal. Complications were often mild. In the case of withdrawal, the complication was transient (within the first 24-28 h of therapy) and self-limited. We had to cease the drug in two cases (5.9%) because of severe withdrawal symptoms.

CONCLUSION

Naltrexone can be used in the treatment of pruritus in cholestatic patients and is a safe drug showing few, mild and self-limited complications.

5-hydroxytryptamine release in the anterior hypothalamic and the hippocampal areas of cholestatic rats

Cholestasis contributes to the genesis of fatigue through several mechanisms. Among these mechanisms, affected serotonergic neurotransmission is important in the pathogenesis of central fatigue. Previously, elevated levels of 5-hydroxyindole acetic acid (5-HIAA), the metabolite of 5-hydroxytryptamine (5-HT) and increased 5-HT(2) receptor density were demonstrated in the anterior hypothalamus and in the hippocampus of bile duct resected rats (BDR), respectively. The aim of this paper is to demonstrate evoked 5-HT release in selected brain regions like anterior hypothalamus and hippocampal CA1 regions of cholestatic rats using BDR rats as an experimental model for cholestasis. In this study, we analyzed the K+ evoked 5-HT and its metabolite 5-HIAA levels by using HPLC with electrochemical detection in the microdialysis samples collected from anterior hypothalamic and hippocampal CA1 regions of sham-operated and BDR rats (n = 6). The ratios of [5-HIAA] to [5-HT] following perfusion with 100 mM K+ artificial cerebrospinal fluid was used for the comparison of the evoked release of 5-HT. Locomotor activity was used to assess the signs of cholestasis associated fatigue in the BDR rats. The vertical and horizontal activity counts within 15 min were found to be decreased in the BDR rats compared to sham-operated rats (p < 0.05). Besides, the number of fecal boli (an index of emotionality) was also significantly fewer in the cholestatic rats (p < 0.05). No significant difference between the sham-operated and the BDR rats was detected in the basal 5-HT and 5-HIAA levels of anterior hypothalamus. K+ stimulation yielded a more profound increase in the [5-HIAA]/[5-HT] in the BDR rats (p < 0.05). The basal levels of 5-HT in CA1 region of the BDR rats was found to be lower than that of sham-operated group (p < 0.05), but no significant difference was observed in terms of evoked 5-HT release in both sham-operated and BDR rats. These findings imply the presence of affected serotonergic system in cholestasis.