Pharmacological characterization of the first in class clinical candidate PF-05190457: a selective ghrelin receptor competitive antagonist with inverse agonism that increases vagal afferent firing and glucose-dependent insulin secretion ex vivo.

BACKGROUND AND PURPOSE: Ghrelin increases growth hormone secretion, gastric acid secretion, gastric motility and hunger but decreases glucose-dependent insulin secretion and insulin sensitivity in humans. Antagonizing the ghrelin receptor has potential as a therapeutic approach in the treatment of obesity and type 2 diabetes. Therefore, the aim was to pharmacologically characterize the novel small-molecule antagonist PF-05190457 and assess translational pharmacology ex vivo. EXPERIMENTAL APPROACH: Radioligand binding in filter and scintillation proximity assay formats were used to evaluate affinity, and europium-labelled GTP to assess functional activity. Rat vagal afferent firing and calcium imaging in dispersed islets were used as native tissues underlying food intake and insulin secretion respectively. KEY RESULTS: PF-05190457 was a potent and selective inverse agonist on constitutively active ghrelin receptors and acted as a competitive antagonist of ghrelin action, with a human Kd of 3 nM requiring 4 h to achieve equilibrium. Potency of PF-05190457 was similar across different species. PF-05190457 increased intracellular calcium within dispersed islets and increased vagal afferent firing in a concentration-dependent manner with similar potency but was threefold less potent as compared with the in vitro Ki in recombinant overexpressing cells. The effect of PF-05190457 on rodent islets was comparable with glibenclamide, but glucose-dependent and additive with the insulin secretagogue glucagon-like peptide-1. CONCLUSIONS AND IMPLICATIONS: Together, these data provide the pharmacological in vitro and ex vivo characterization of the first ghrelin receptor inverse agonist, which has advanced into clinical trials to evaluate the therapeutic potential of blocking ghrelin receptors in obesity and type 2 diabetes.

Cardiovascular risk, lipidemic phenotype and steatosis. A comparative analysis of cirrhotic and non-cirrhotic liver disease due to varying etiology.

BACKGROUND: Liver regulates lipid metabolism in health and disease states. Nevertheless, the entity of cardiovascular risk (CVR) resulting from dysregulation of lipid metabolism secondary to liver disease is poorly characterized. AIM AND METHODS: To review, based on a PubMed literature search, the features and the determinants of serum lipid phenotype and its correlation with hepatic steatosis, insulin resistance (IR) and CVR across the wide spectrum of the most common chronic liver diseases due to different etiologies. RESULTS: Alcoholic liver disease (ALD) is associated with steatosis, IR and a typical lipid profile. The relationship between alcohol intake, incident type 2 diabetes (T2D) and CVR describes a J-shaped curve. Non-alcoholic fatty liver disease (NAFLD), and probably nonalcoholic steatohepatitis (NASH) in particular, is associated with IR, atherogenic dyslipidemia and increased CVR independent of traditional risk factors. Moreover, NASH-cirrhosis and T2D contribute to increasing CVR in liver transplant recipients. HBV infection is generally free from IR, steatosis and CVR. HCV-associated dysmetabolic syndrome, featuring steatosis, hypocholesterolemia and IR, appears to be associated with substantially increased CVR. Hyperlipidemia is an almost universal finding in primary biliary cirrhosis, a condition typically spared from steatosis and associated with neither subclinical atherosclerosis nor excess CVR. Finally, little is known on CVR in patients with hepatocellular carcinoma. CONCLUSIONS: CVR is increased in ALD, NAFLD and chronic HCV infection, all conditions featuring IR and steatosis. Therefore, irrespective of serum lipid phenotype, hepatic steatosis and IR may be major shared determinants in amplifying CVR in common liver disease due to varying etiology.

Odontostomatological aspects in patients with Williams syndrome: a series of 4 cases.

The authors examined four patients with Williams syndrome presenting characteristic odontostomatological alterations. Agenesis, dental deposits, chewing difficulties due to bone malformations and poor cooperation of patients with malformations also in other districts and mental and physical retardation require the dentist to adopt different approaches, from restorative to orthodontic treatment, from periodontal to professional oral hygiene treatment.

Odontostomatological aspects in patients with Goldenhar syndrome: a series of 9 patients.

The authors observed and followed nine patients with Goldenhar syndrome to identify the variability and severity malformations mainly affecting the orofacial district, but also other systems. Considering the severity of the lesions and the affected organs and tissues, the authors report preventive and therapeutic approaches, which present considerable difficulties in timing and quality of interventions.

Increased appearance rate of 27-hydroxycholesterol in vivo in hypercholesterolemia: a possible compensatory mechanism.

BACKGROUND AND AIMS: The first step in the alternative pathway of bile acid biosynthesis is the 27-hydroxylation of cholesterol, which takes place both in liver and extrahepatic tissues. This pathway is believed to play a role in peripheral cholesterol degradation. Aim of this study was to investigate the impact of hyperlipidemia on 27-hydroxycholesterol appearance rate, and to assess the effects induced by treatment with statins. METHODS AND RESULTS: Seven patients with familial hypercholesterolemia and eight patients with familial combined hyperlipidemia underwent determination of 27-hydroxylation rates in vivo by i.v. infusion of deuterated 27-hydroxycholesterol. Isotope enrichment was assayed by gas chromatography-mass spectrometry, allowing to calculate 27-hydroxycholesterol appearance rates. Six normocholesterolemic subjects were regarded as controls. In some hypercholesterolemic patients the infusions were repeated during treatment with atorvastatin or rosuvastatin. Hydroxylation rates were higher in hypercholesterolemic patients (8.7 ± 2.5 mg/h; controls, 3.4 ± 2.0 mg/h; combined hyperlipidemia, 4.4 ± 1.6 mg/h; mean ± SD, P < 0.01 vs both). After statin treatment, both plasma cholesterol levels and hydroxylation rates dropped by nearly 50%. No difference was detectable between the two statins. A linear correlation was shown between plasma cholesterol and 27-hydroxylation rates. CONCLUSION: Hypercholesterolemia associates with increased 27-hydroxycholesterol appearance rates, which decrease during hypocholesterolemic treatment. The correlation with cholesterol levels supports the view that 27-hydroxylation may act as a compensatory mechanism in a condition of larger plasma cholesterol pool. A regulatory role for hepatic and extrahepatic nuclear receptors seems reasonable. These data prompt novel pharmacological approaches for the management of hypercholesterolemia and the prevention of atherosclerosis.

Risk for cardiovascular events in an Italian population of patients with type 2 diabetes.

BACKGROUND AND AIM: This study aims to analyse the risk of cardiovascular events in a local cohort of patients with type 2 diabetes, and to evaluate the prognostic accuracy of four algorithms used to estimate cardiovascular risk: the Framingham study, United Kingdom Prospective Diabetes Study (UKPDS), Riskard study and Progetto Cuore. METHOD AND RESULTS: We analysed clinical charts of the Diabetes Clinics of Modena for the period 1991-95. Patients in the age range of 35-65 with type 2 diabetes and no previous cardiovascular disease were eligible. The incidence of new cardiovascular disease was compared with estimated rates deriving from the different functions. A stratification was obtained in subgroups at different cardiovascular risk, allowing comparison between the algorithms. A total of 1532 patients were eligible; women presented a worse cardiovascular risk profile. An absolute 10-year rate of cardiovascular events of 14.9% was observed. Comparing patients with events with event-free subjects, we found significant differences in systolic blood pressure, age at visit, smoking, high-density lipoprotein (HDL)-cholesterol, duration of diabetes, glycosylated haemoglobin (HbA1c) and co-morbidities. Comparing the estimated risk rate according to the different functions, Italian algorithms were more consistent with observed data; however, Progetto Cuore and Riskard show underestimation of events when applied to females. CONCLUSIONS: Estimation of cardiovascular risk is dependent on the algorithm adopted and on the baseline risk of the reference cohort. Functions designed for a specific population, including risk variables peculiar for diabetes, should be adopted to increase the performance of such functions which is clearly unsatisfactory at present.

Practice guidelines for the diagnosis and management of nonalcoholic fatty liver disease. A decalogue from the Italian Association for the Study of the Liver (AISF) Expert Committee.

We report the evidence-based Italian Association for the Study of Liver guidelines for the appropriate diagnosis and management of patients with nonalcoholic fatty liver disease in clinical practice and its related research agenda. The prevalence of nonalcoholic fatty liver disease varies according to age, gender and ethnicity. In the general population, the prevalence of nonalcoholic fatty liver disease is about 25% and the incidence is of two new cases/100 people/year. 2-3% of individuals in the general population will suffer from nonalcoholic steatohepatitis. Uncomplicated steatosis will usually follow a benign course. Individuals with nonalcoholic steatohepatitis, however, have a reduced life expectancy, mainly owing to vascular diseases and liver-related causes. Moreover, steatosis has deleterious effects on the natural history of HCV infection. Nonalcoholic fatty liver disease is usually diagnosed in asymptomatic patients prompted by the occasional discovery of increased liver enzymes and/or of ultrasonographic steatosis. Medical history, complete physical examination, etiologic screening of liver injury, liver biochemistry tests, serum lipids and insulin sensitivity tests should be performed in every patient. Occult alcohol abuse should be ruled out. Ultrasonography is the first-line imaging technique. Liver biopsy, the gold standard in diagnosis and prognosis of nonalcoholic fatty liver disease, is an invasive procedure and its results will not influence treatment in most cases but will provide prognostic information. Assessment of fibrosis by composite scores, specific laboratory parameters and transient elastography might reduce the number of nonalcoholic fatty liver disease patients requiring liver biopsy. Dieting and physical training reinforced by behavioural therapy are associated with improved nonalcoholic fatty liver disease. Diabetes and the metabolic syndrome should be ruled out at timed intervals in nonalcoholic fatty liver disease. Nonalcoholic steatohepatitis patients should undergo periodic evaluation of cardiovascular risk and of advancement of their liver disease; those with nonalcoholic steatohepatitis-cirrhosis should be evaluated for early diagnosis of hepatocellular carcinoma.

Genetic polymorphisms in non-alcoholic fatty liver disease: interleukin-6-174G/C polymorphism is associated with non-alcoholic steatohepatitis.

BACKGROUND: Environmental and genetic factors play a role in the pathogenesis and natural history of non-alcoholic fatty liver disease (NAFLD). METHODS: In 114 subjects with NAFLD we report the prevalence and correlation with clinical parameters of three polymorphisms: interleukin-6 (-174G/C), plasma cell differentiation antigen (K121Q) and microsomal transfer protein (-493G/T). In 59 biopsied patients with NAFLD the polymorphisms were also related to histological features. RESULTS: IL-6 -174C variant was more prevalent (p<0.01) in NAFLD compared to controls. In the NAFLD group, C carriers had higher HOMA-IR and fasting insulin than G carriers (p<0.05). The prevalence of IL-6/C variant was higher (83%) in biopsied than in not biopsied subjects (66%) (p<0.05). In biopsied subjects, C carriers had higher HOMA and fasting insulin (p<0.05) compared than those with G allele. The prevalence of IL-6 -174G/C polymorphism was significantly higher in NASH than in NAFLD (p=0.048). At logistic regression analysis IL-6 -174C was an independent predictor of both NAFLD (OR 4.116, C.I. 1.126-15.048) and NASH (OR 7.035, C.I. 1.167-42.394). Conversely, the distribution of PC-1 and MTP polymorphisms was not significantly different compared to the control group, nor associated with clinical or histological characteristics. CONCLUSIONS: Our data suggest that IL-6 -174C genetic polymorphisms, involved in inflammation and insulin resistance, are associated with NASH. These data may contribute to the understanding of the genetic susceptibility to NAFLD.

Nuclear receptors as potential molecular targets in cholesterol accumulation conditions: insights from evidence on hepatic cholesterol degradation and gallstone disease in humans.

The liver plays a central role in the regulation of cholesterol homeostasis. Hepatic cholesterol content is maintained by a complex interplay between input and output pathways; alterations in the balance among these processes may lead to accumulation of excess cholesterol in body compartments with potentially deleterious consequences at the level of blood vessels (atherosclerosis) and biliary tract (gallstone disease). Molecular biology has brought new insights into this field. Nuclear receptors have been shown to play a key role in the "sensing" of intracellular cholesterol levels and in the triggering of metabolic responses via the sterol regulatory element binding protein (SREBP) cascade. A nuclear receptor for bile acids, farnesoid X receptor (FXR), has been identified and the molecular pathways underlying feedback inhibition of bile acid synthesis, the main mechanism of irreversible degradation of cholesterol, have been clarified. Such regulation involves a number of additional coactivators/corepressors of the transcription of the limiting enzyme of bile acid synthesis, cholesterol 7alpha-hydroxylase. Finally, the main transporters of biliary lipids (bile acids, phospholipids and cholesterol) have been described; most of them undergo transcriptional control by nuclear receptors, allowing regulation of biliary lipid efflux in conditions of different intracellular availability. Despite a body of evidence coming from experimental models the intimate mechanisms of regulation have not been clearly defined and direct evidence in humans is rather limited. This review will focus on the role of nuclear receptors in the regulation of hepatic cholesterol degradation and biliary lipid secretion, and on the theoretical applications from a pharmacotherapeutic perspective.

HCV and diabetes. A two-question-based reappraisal.

We used available studies to answer two clinically relevant questions, i.e. whether those with type 2 diabetes should undergo hepatitis C virus screening and whether hepatitis C virus positive individuals should be screened for diabetes. Four reasons argue against the hypothesis of screening diabetics for hepatitis C virus. First, although it induces insulin resistance, hepatitis C virus is not directly diabetogenic. Second, the clinical phenotype of hepatitis C virus-associated type 2 diabetes might be a clue to target the specific diabetic population to be screened. Third, diabetic patients are expected to be poor responders to antivirals and evidence that this might result in recovery from type 2 diabetes is insufficient. Fourth, no econometric data are available in the specific subset of those with type 2 diabetes. Case finding of type 2 diabetes in those with hepatitis C virus infection, in contrast, might be considered in those patients with type 2 diabetes who have cirrhosis, in whom--due to increased prevalence and severity of hepatic encephalopathy--diabetes is associated with increased mortality. Preliminary evidence suggests that the prognosis of cirrhosis might benefit from improved glycemic control and thus from earlier diagnosis of type 2 diabetes. Finally, studies are needed to ascertain the most cost-effective strategy of case-finding type 2 diabetes among those who are hepatitis C virus-infected. In conclusion, available data enabled us to answer the two questions. Hepatitis C virus screening should best be restricted to those (lean) diabetic patients with (advanced) liver disease. Glucose tolerance testing should best be performed in those with hepatitis C virus-related cirrhosis. However, additional studies are needed to support the cost-effectiveness of our conclusions.

Non-alcoholic fatty liver disease (NAFLD) and cardiovascular disease: an open question.

AIMS: To review available data concerning the basic science and epidemiological-clinical evidence for an association of NAFLD and cardiovascular disease. DATA SYNTHESIS: Non-alcoholic fatty liver disease (NAFLD) defines alcohol-like hepatic histological lesions seen in the non-alcoholic, insulin resistant patient representing the hepatic counterpart of the metabolic syndrome. Along with insulin resistance, additional genetic, endocrine and vascular changes together with environmental stimuli--which are also involved in the pathogenesis of atherosclerosis--play a prominent role in the development and progression of NAFLD. Clinical and epidemiological studies seem to indicate that NAFLD is associated with an increased risk for cardiovascular disease but further studies are needed to confirm the available data. The mainstay of NAFLD treatment is based on the correction of the same metabolic changes that predispose to atherosclerosis. CONCLUSIONS: Non-invasive evaluation of risk for cardiovascular events is recommended in all individuals presenting with NAFLD and conversely, the presence of NAFLD should always be looked for in subjects with features belonging to the metabolic syndrome. Further studies are needed on the mechanisms linking fatty liver and vascular diseases.

Age-related changes in bile acid synthesis and hepatic nuclear receptor expression.

BACKGROUND: Recent data highlighted the role of nuclear receptors in the transcriptional regulation of the limiting enzyme of bile acid synthesis, cholesterol 7alpha-hydroxylase, in cellular and animal models. This study was designed to analyze the effects of age on cholesterol 7alpha-hydroxylase and related nuclear receptor expression in human livers. DESIGN: Surgical liver biopsies were obtained in 23 patients requiring operation on the gastrointestinal tract. mRNA levels of cholesterol 7alpha-hydroxylase and related nuclear receptors and co-activators were assayed by quantitative real-time RT-PCR. Serum levels of 7alpha-hydroxy-4-cholesten-3-one, a marker of bile acid synthesis, were assayed by gas-liquid chromatography:mass spectrometry. RESULTS: Ageing was inversely correlated with serum 7alpha-hydroxy-4-cholesten-3-one and with cholesterol 7alpha-hydroxylase mRNA levels (r = -0.44 and r = -0.45 on a semi-log scale, respectively, P < 0.05). Among different nuclear factors, cholesterol 7alpha-hydroxylase mRNA best correlated with hepatocyte nuclear factor-4 (r = 0.55 on a log scale, P < 0.05); hepatocyte nuclear factor-4 levels were also inversely correlated with age (r = -0.64 on a semi-log scale, P < 0.05). Age was inversely correlated with serum insulin-like growth factor-I levels, which were directly correlated with hepatocyte nuclear factor-4 and cholesterol 7alpha-hydroxylase expression. No suppressive effect of short heterodimer partner expression on cholesterol 7alpha-hydroxylase was observed. CONCLUSIONS: Ageing associates with reduced bile acid synthesis, possibly related to decreased hepatic expression of hepatocyte nuclear factor-4 and consequently of cholesterol 7alpha-hydroxylase. Age-related modifications of the growth hormone/insulin-like growth factor axis might play a role. These findings may help to elucidate the pathophysiology of age-related modifications of cholesterol metabolism.

Is cholangiocarcinoma another complication of insulin resistance: a report of three cases.

BACKGROUND: Cholangiocarcinoma is the second most common primary liver cancer, and the number of cases of intrahepatic cholangiocarcinoma (ICC) have been steadily increasing worldwide. Although the reasons for this surge are unknown, insulin resistance (IR) could be a risk factor, similar to what has been reported for other cancers. CASE REPORT: We report on 3 cases of ICC arising in subjects sharing IR as an underlying risk factor. Case 1 was an obese and dyslipidemic patient with NAFLD. The second and the third patients were affected by type 2 diabetes. CONCLUSIONS: Evidence for a link between IR and onset of cholangiocarcinoma in our patients rests on three lines of evidence: epidemiological, biological, and exclusion of others risk factors. Studies are needed to confirm our hypothesis that IR is a risk factor for the development of ICC.

Decreased hepatic expression of PPAR-gamma coactivator-1 in cholesterol cholelithiasis.

BACKGROUND: Cholesterol cholelithiasis (gallstone disease) is a common disease in the Western world. The aim of the present study was to analyze the hepatic expression of a number of nuclear receptors involved in bile acid metabolism in human cholesterol gallstone disease. MATERIALS AND METHODS: Surgical liver biopsies were obtained from 11 patients with untreated cholesterol cholelithiasis and nine gallstone-free subjects; mRNA levels of cholesterol 7alpha-hydroxylase (CYP7A1) and related nuclear receptors and coactivators were assayed by quantitative real-time RT-PCR. RESULTS: No differences between the two groups were detected in mRNA levels of CYP7A1 and related nuclear receptors, with the exception of peroxysome proliferator-activated receptor-gamma coactivator 1 (PGC-1), which was significantly (P < 0.01) less expressed in gallstone subjects. Expression of PGC-1 was linearly correlated with farnesoid X receptor (FXR) in gallstone patients (r = 0.87 on a log scale, P < 0.01), but not in control subjects; in gallstone patients PGC-1 expression was also correlated with hepatocyte nuclear factor 4 (HNF-4) (r = 0.78, P < 0.01). CONCLUSION: These findings suggest that PGC-1 can play a role in the prevention of cholesterol gallstone disease in humans; this might take place via interaction with the bile acid receptor FXR, whose protective role in cholelithiasis has been suggested by recent evidence in animal models and other coactivators. The present data might help to understand the pathophysiology and possibly focus on new therapeutical targets in cholesterol gallstone disease.

Hepatitis C and steatosis: a reappraisal.

The overall prevalence of steatosis in patients with Hepatitis C virus (HCV) chronic infection is 55.5% (range 34.8-81.2%). This is a two to threefold increase compared with the prevalence of steatosis in chronic hepatitides because of other aetiologies and of the figures expected on the grounds of a steatosis-HCV chance association. HCV genotype 3 (HCV-3) has specific epidemiological features; furthermore, as compared with HCV-non-3 genotypes, it is associated with a higher prevalence (74.1%vs 47.9%, P < 0.01) and with more severe grades of steatosis (prevalence of grade 3 steatosis 29.6 vs 5.5 P < 0.01). Host and viral factors play a role, although to a variable extent, in the pathogenesis of HCV-3 and non-3 steatosis. HCV load and body mass index are associated with steatosis in HCV-3 and in HCV-non-3 patients respectively. Serum cholesterol levels and liver steatosis at baseline follow an inverse relationship in HCV infection. As hypocholesterolaemia corrects only in those sustained responders to antiviral treatment both in genotype 3 and in non-3 genotypes, the occurrence of a virally induced, acquired and reversible hypobetalipoproteinaemia seems plausible. Steatosis affects the natural course of HCV infection: it is associated with fibrosis, a possible mediator of increased risk to develop type 2 diabetes, it impairs the response to antiviral treatment in HCV-3 patients and might constitute a risk factor for the development of hepatocellular carcinoma. These observations indicate the need to evaluate the efficacy of combined antiviral and 'metabolic' approaches vs standard antiviral regimes in patients with steatosis and HCV chronic infection.

Review article: diabetes, genetics and ethnicity.

The prevalence of insulin resistance and diabetes has increased in the past decades at an alarming rate in all Western countries and in those countries which are adopting a 'western life style'. This trend suggests the impact of environmental factors such as diet, obesity and physical activity on the pathogenesis of diabetes. However it is known that the prevalence and variation of prevalence, as consequence of environmental changes, it is different in various ethnic groups. Studies conducted in multiethnic populations suggest that some ethnic groups, such as Hispanics or Asian Indians, might have a particular predisposition, possibly on genetic basis, to develop insulin resistance and diabetes, when exposed to adverse conditions. According to the 'thrifty gene' hypothesis, a clustering of different genetic defects or polymorphisms, developed as genetic advantage in some populations, could predispose some ethnic groups to insulin resistance and diabetes in presence of an increased food supply. Multiple mutations, associated with small changes in insulin sensitivity, when combined, may induce a significant reduction in insulin sensitivity. This review deals with the possible relevance of genetic factors in the expression of insulin resistance and diabetes in relation to ethnicity.

Review article: the metabolic syndrome and non-alcoholic fatty liver disease.

Metabolic syndrome represents a common risk factor for premature cardiovascular disease and cancer whose core cluster includes diabetes, hypertension, dyslipidaemia and obesity. The liver is a target organ in metabolic syndrome patients in which it manifests itself with non-alcoholic fatty liver disease spanning steatosis through hepatocellular carcinoma via steatohepatitis and cirrhosis. Given that metabolic syndrome and non-alcoholic fatty liver disease affect the same insulin-resistant patients, not unexpectedly, there are amazing similarities between metabolic syndrome and non-alcoholic fatty liver disease in terms of prevalence, pathogenesis, clinical features and outcome. The available drug weaponry for metabolic syndrome includes aspirin, metformin, peroxisome proliferator-activated receptor agonists, statins, ACE (angiotensin I-converting enzyme) inhibitors and sartans, which are potentially or clinically useful also to the non-alcoholic fatty liver disease patient. Studies are needed to highlight the grey areas in this topic. Issues to be addressed include: diagnostic criteria for metabolic syndrome; nomenclature of non-alcoholic fatty liver disease; enlargement of the clinical spectrum and characterization of the prognosis of insulin resistance-related diseases; evaluation of the most specific clinical predictors of metabolic syndrome/non-alcoholic fatty liver disease and assessment of their variability over the time; characterization of the importance of new risk factors for metabolic syndrome with regard to the development and progression of non-alcoholic fatty liver disease.

Review article: hepatic steatosis and insulin resistance.

Hepatic steatosis may be both an adaptive phenomenon and an example of lipotoxicity. Its prevalence ranks in the same order of magnitude of insulin resistance in the general population. Studies support the finding that hepatic steatosis is secondary to insulin resistance and not vice versa. A steatotic liver will further contribute to the development of insulin resistance through impaired clearance of insulin from the portal blood, creating a vicious cycle. Insulin resistance is the leading force in the pathogenesis and natural history of non-alcoholic fatty liver disease. Dysfunction of energetic homeostasis and the interaction of adiponectin, leptin and tumour necrosis factor-alpha are key events in the pathogenesis of steatosis and insulin resistance. Insulin resistance represents the frame within which hepatic and extrahepatic non-alcoholic fatty liver disease-related clinical manifestations are to be anticipated and interpreted.

'True' antimitochondrial antibody-negative primary biliary cirrhosis, low sensitivity of the routine assays, or both?

Anti-mitochondrial antibody (AMA) is considered the serological hallmark of primary biliary cirrhosis (PBC), but may be missing in a proportion of these patients. We assessed sensitivity and specificity of the currently available techniques for AMA detection in a large series of PBC patients and controls, and analysed their clinical and immunological features according to the AMA status. By indirect immunofluorescence on rat tissue sections and HEp-2 cells, Western immunoblot with bovine submitochondrial particles, and two ELISAs with AMA-specific recombinant proteins, we evaluated the presence of AMA in 127 PBC patients, 166 patients with type 1 autoimmune hepatitis and 100 with non alcoholic fatty liver disease. In PBC patients Western immunoblot detects AMA significantly more often than indirect immunofluorescence on HEp-2 cells (85%versus 72%, P = 0.02) or rodent tissue sections (71%, P = 0.01); both ELISAs are only slightly less sensitive than Western immunoblot (81% and 78%). Ten patients with non alcoholic fatty liver disease were AMA-positive by indirect immunofluorescence, but none recognized AMA-specific epitopes in Western immunoblot or in ELISAs. Twelve patients with type 1 autoimmune hepatitis were AMA-positive by indirect immunofluorescence, but only 6 (3.6%) reacted by Western immunoblot and ELISAs. Western immunoblot or ELISA should be regarded as first-line assay for the detection of AMA. Up to 15% of PBC patients are consistently AMA-negative, yet they share the same clinical, biochemical and histological features of AMA-positive PBC. Detection of AMA in type 1 autoimmune hepatitis might identify a subset of patients at risk of developing a hepatitic/cholestatic syndrome.