Variants in PCSK7, PNPLA3 and TM6SF2 are risk factors for the development of cirrhosis in hereditary haemochromatosis.

BACKGROUND: Cirrhosis develops in <10% of individuals homozygous for the C282Y variant in the homeostatic iron regulator (HFE) gene. Carriage of PCSK7:rs236918 is associated with an increased risk of cirrhosis in this population. AIM: To determine if genetic variants significantly associated with the risk of alcohol- and NAFLD-related cirrhosis also modulate the cirrhosis risk in C282Y homozygotes. METHODS: Variants in PCSK7, PNPLA3, TM6SF2, MBOAT7 and HSD17B13 were genotyped in 1319 C282Y homozygotes, from six European countries, of whom 171 (13.0%) had cirrhosis. Genotypic and allelic associations with the risk for developing cirrhosis were assessed, adjusting for age and sex. Fixed effects meta-analyses of the adjusted summary data for each country were performed. Post hoc association testing was undertaken in the 131 (76.6%) cases and 299 (26.0%) controls with available liver histology. RESULTS: Significant associations were observed between PCSK7:rs236918 (OR = 1.52 [95% CI 1.06-2.19]; P = 0.022; I2  = 0%); PNPLA3:rs738409 (OR = 1.60 [95% CI 1.22-2.11]; P = 7.37 × 10-4 ; I2  = 45.5%) and TM6SF2:rs58542926 (OR = 1.94 [95% CI 1.28-2.95]; P = 1.86 × 10-3 ; I2  = 0%) and the cirrhosis risk in C282Y homozygotes. These findings remained significant in the subpopulation with available liver histology. The population-attributable fractions were 5.6% for PCSK7:rs236918, 13.8% for PNPLA3:rs738409, 6.5% for TM6SF2:rs58542926 and 24.0% for carriage of all three variants combined. CONCLUSIONS: The risk of cirrhosis associated with carriage of PCSK7:rs236918 was confirmed in this much larger population of C282Y homozygotes. In addition, PNPLA3:rs738409 and TM6SF2:rs58542926 were established as significant additional risk factors. More detailed genetic testing of C282Y homozygotes would allow risk stratification and help guide future management.

Changes in the Intestinal Microbiome during a Multispecies Probiotic Intervention in Compensated Cirrhosis.

Probiotics have been used in trials to therapeutically modulate the gut microbiome and have shown beneficial effects in cirrhosis. However, their effect on the microbiome of cirrhosis patients is not fully understood yet. Here, we tested the effects of a multispecies probiotic on microbiome composition in compensated cirrhosis. The gut microbiome composition of 58 patients with compensated cirrhosis from a randomized controlled trial who received a daily dose of multispecies probiotics or placebo for six months was analysed by 16S rRNA gene sequencing. Microbiome composition of patients who received probiotics was enriched with probiotic strains and the abundance of Faecalibacterium prausnitzii, Syntrophococcus sucromutans, Bacteroides vulgatus, Alistipes shahii and a Prevotella species was increased in the probiotic group compared to the placebo group. Patients who had microbiome changes in response to probiotic treatment also showed a significant increase in neopterin and a significant decrease in faecal zonulin levels after intervention, which was not observed in placebo-treated patients or patients with unchanged microbiome compositions. In conclusion, multispecies probiotics may enrich the microbiome of compensated cirrhotic patients with probiotic bacteria during a six-month intervention and beneficially change the residential microbiome and gut barrier function.

FXR-dependent Rubicon induction impairs autophagy in models of human cholestasis.

BACKGROUND & AIMS: Cholestasis comprises a spectrum of liver diseases characterized by the accumulation of bile acids. Bile acids and activation of the farnesoid X receptor (FXR) can inhibit autophagy, a cellular self-digestion process necessary for cellular homeostasis and regeneration. In mice, autophagy appears to be impaired in cholestasis and induction of autophagy may reduce liver injury. METHODS: Herein, we explored autophagy in human cholestasis in vivo and investigated the underlying molecular mechanisms in vitro. FXR chromatin immunoprecipitation-sequencing and qPCR were performed in combination with luciferase promoter studies to identify functional FXR binding targets in a human cholestatic liver sample. RESULTS: Autophagic processing appeared to be impaired in patients with cholestasis and in individuals treated with the FXR ligand obeticholic acid (OCA). In vitro, chenodeoxycholic acid and OCA inhibited autophagy at the level of autophagosome to lysosome fusion in an FXR-dependent manner. Rubicon, which inhibits autophago-lysosomal maturation, was identified as a direct FXR target that is induced in cholestasis and by FXR-agonistic bile acids. Genetic inhibition of Rubicon reversed the bile acid-induced impairment of autophagic flux. In contrast to OCA, ursodeoxycholic acid (UDCA), which is a non-FXR-agonistic bile acid, induced autophagolysosome formation independently of FXR, enhanced autophagic flux and was associated with reduced Rubicon levels. CONCLUSION: In models of human cholestasis, autophagic processing is impaired in an FXR-dependent manner, partly resulting from the induction of Rubicon. UDCA is a potent inducer of hepatic autophagy. Manipulating autophagy and Rubicon may represent a novel treatment concept for cholestatic liver diseases. LAY SUMMARY: Autophagy, a cellular self-cleansing process, is impaired in various forms of human cholestasis. Bile acids, which accumulate in cholestatic liver disease, induce Rubicon, a protein that inhibits proper execution of autophagy. Ursodeoxycholic acid, which is the first-line treatment option for many cholestatic liver diseases, induces hepatic autophagy along with reducing Rubicon.

Cholemic nephropathy - Historical notes and novel perspectives.

Acute kidney injury is common in patients with liver disease and associated with significant morbidity and mortality. Besides bacterial infections, fluid loss, and use of nephrotoxic drugs AKI in liver disease may be triggered by tubular toxicity of cholephiles. Cholemic nephropathy, also known as bile cast nephropathy, supposedly represents a widely underestimated but important cause of renal dysfunction in cholestasic or advanced liver diseases with jaundice. Cholemic nephropathy describes impaired renal function along with characteristic histomorphological changes consisting of intratubular cast formation and tubular epithelial cell injury directed towards distal nephron segments. The underlying pathophysiologic mechanisms are not entirely understood and clear defined diagnostic criteria are still missing. This review aims to summarize (i) the present knowledge on clinical and morphological characteristics of cholemic nephropathy, (ii) available preclinical models, (iii) potential pathomechanisms especially the potential role of bile acids, and (iv) future diagnostic and therapeutic strategies for cholemic nephropathy. This article is part of a Special Issue entitled: Cholangiocytes in Health and Disease edited by Jesus Banales, Marco Marzioni, Nicholas LaRusso and Peter Jansen.

Genetic loss of the muscarinic M3 receptor markedly alters bile formation and cholestatic liver injury in mice.

AIM: Hepatic innervation represents a potentially underestimated regulator of liver function and regeneration. The muscarinic 3 receptor (M3 -R) is the primary cholangiocyte receptor for the afferent parasympathetic innervation of bile ducts. We aimed to determine the specific role of the M3 -R in bile formation and models for cholestatic liver disease in mice. METHODS: We compared bile flow and composition in M3 -R knock-out mice (M3 -R-/- ) and wild type littermates (WT). Furthermore, we compared liver inury of M3 -R-/- and WT mice after 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) feeding, a well-characterized preclinical model of cholestatic liver disease. To analyze the possible role of the M3 -R as a therapeutic target, we treated 4-week-old Mdr2-/- mice, a preclinical model for sclerosing cholangitis, with the M3 -R agonist bethanechol for 4 weeks. RESULTS: M3 -R-/- mice showed significantly reduced bile flow compared to WT mice, most likely due to decreased biliary HCO3- secretion. However, even aged M3 -R-/- mice did not spontaneously develop liver injury or cholestasis. Challenging M3 -R-/- and WT littermates with DDC feeding showed substantially aggravated liver injury in M3 -R-/- mice. After 4 weeks bethanechol treatment, Mdr2-/- mice showed less liver injury compared to controls. CONCLUSION: Our experimental findings suggest that M3 -R-signalling significantly influences bile formation. Loss of the M3 -R increases susceptibility to cholestatic injury in DDC-fed mice. Since treatment of Mdr2-/- mice with a M3 -R agonist decreases liver injury, M3-R signaling may represent a therapeutic target in specific cholangiopathies.

Austrian consensus guidelines on the management and treatment of portal hypertension (Billroth III).

The Billroth III guidelines were developed during a consensus meeting of the Austrian Society of Gastroenterology and Hepatology (ÖGGH) and the Austrian Society of Interventional Radiology (ÖGIR) held on 18 February 2017 in Vienna. Based on international guidelines and considering recent landmark studies, the Billroth III recommendations aim to help physicians in guiding diagnostic and therapeutic strategies in patients with portal hypertension.

Ultrasound verified inflammation and structural damage in patients with hereditary haemochromatosis-related arthropathy.

BACKGROUND: Chronic arthropathy occurs in approximately two thirds of patients with hereditary haemochromatosis (HH). The aim was to study inflammatory and structural lesions in patients with HH with (HH-A) and without arthropathy (HH-WA) using ultrasonography. METHODS: This was a cross-sectional study of 26 patients with HH-A, 24 with HH-WA and 37 with hand osteoarthritis (HOA). Clinical examination was performed in 68 joints, and we retrieved data on hand function, pain and global disease activity (all using a visual analogue scale (VAS)), morning stiffness and ferritin levels. Standard x-ray and ultrasound were conducted in 36 joints (hands, hips, knees and ankles), and we graded grey scale synovitis (GSS), power Doppler ultrasound (PD), osteophytes, erosions, tenosynovitis and cartilage damage semi-quantitatively in accordance with prior publications. RESULTS: Ultrasound revealed a high proportion of inflammatory changes in HH-A; GSS was found in 96.2% and PD signals in 80.8% of patients (median GSS score 9, PD score 2.5). The frequency of these findings was similar in HOA. Inflammation was also common in HH-WA, yielding GSS in 83.3% and PD signals in 50.0% of patients. Cartilage damage was most prominent in HH-A as compared to HH-WA and HOA (median scores 11.0, 2.5 and 2.0, respectively). The prevalence and extent of erosions and osteophytes were similar in all groups. None of the ultrasound scores was associated with pain or function; GSS, PD, osteophyte and cartilage scores correlated with x-ray-verified structural damage. CONCLUSION: A high prevalence of ultrasound-verified inflammation and cartilage damage was found in HH-A, and to a lesser extent in HH-WA. These findings were associated with x-ray-verified damage but not with clinical scores of pain and function.

Renal dysfunction in cirrhosis: acute kidney injury and the hepatorenal syndrome.

Renal dysfunction is a common complication of liver cirrhosis and of utmost clinical and prognostic relevance. Patients with cirrhosis are more prone to developing acute kidney injury (AKI) than the non-cirrhotic population. Pre-renal AKI, the hepatorenal syndrome type of AKI (HRS-AKI, formerly known as 'type 1') and acute tubular necrosis represent the most common causes of AKI in cirrhosis. Correct differentiation is imperative, as treatment differs substantially. While pre-renal AKI usually responds well to plasma volume expansion, HRS-AKI and ATN require different specific approaches and are associated with substantial mortality. Several paradigms, such as the threshold of 2.5 mg/dL for diagnosis of HRS-AKI, have recently been abolished and novel urinary biomarkers are being investigated in order to facilitate early and correct diagnosis and treatment of HRS-AKI and other forms of AKI in patients with cirrhosis. This review summarizes the current diagnostic criteria, as well as pathophysiologic and therapeutic concepts for AKI and HRS-AKI in cirrhosis.

NorUrsodeoxycholic acid ameliorates cholemic nephropathy in bile duct ligated mice.

BACKGROUND & AIMS: Severe cholestasis may cause cholemic nephropathy that can be modeled in common bile duct ligated (CBDL) mice. We aimed to explore the therapeutic efficacy and mechanisms of norursodeoxycholic acid (norUDCA) in cholemic nephropathy. METHODS: In 8-week CBDL mice fed with norUDCA (prior or post CBDL) or chow we evaluated serum urea levels, urine cytology and urinary neutrophil gelatinase associated lipocalin (uNGAL), kidney and liver tissue quantification of fibrosis by hydroxyproline content and gene chip expression looking at key genes of inflammation and fibrosis. Moreover, we comprehensively analysed bile acid profiles in liver, kidney, serum and urine samples. RESULTS: NorUDCA-fed CBDL mice had significantly lower serum urea and uNGAL levels and less severe cholemic nephropathy as demonstrated by normal urine cytology, significantly reduced tubulointerstitial nephritis, and renal fibrosis as compared to controls. NorUDCA underwent extensive metabolism to produce even more hydrophilic compounds that were significantly enriched in kidneys. CONCLUSION: NorUDCA ameliorates cholemic nephropathy due to the formation of highly hydrophilic metabolites enriched in kidney. Consequently, norUDCA may represent a medical treatment for cholemic nephropathy. LAY SUMMARY: The term cholemic nephropathy describes renal dysfunction together with characteristic morphological alterations of the kidney in obstructive cholestasis that can be mimicked by ligation of the common bile duct in mice. Feeding the hydrophilic bile acid norUDCA to bile duct ligated mice leads to a significant amelioration of the renal phenotype due to the formation of highly hydrophilic metabolites enriched in the kidney and may therefore represent a medical treatment for cholemic nephropathy.

Downgrading of a G3 Neuroendocrine Tumor to a G2 Tumor: Can First-Line Cytotoxic Chemotherapy Change the Tumor Biology?

The antiproliferative treatment options for neuroendocrine tumors (NET)/neuroendocrine carcinomas of the gastrointestinal tract critically depend on the proliferation rate, evaluated by immunohistochemical staining for Ki-67. According to their grading, tumors are treated with somatostatin analogs, mTOR inhibitors, or cytotoxic substances. This case illustrates downgrading of a primarily highly proliferative NET achieved by a variation of cytotoxic chemotherapy regimens, followed by a combination therapy using everolimus together with lanreotide. The latter medication might lead to a good clinical response as far as tumor growth is concerned.

Inhibition of intestinal bile acid absorption improves cholestatic liver and bile duct injury in a mouse model of sclerosing cholangitis.

BACKGROUND AND AIMS: Approximately 95% of bile acids (BAs) excreted into bile are reabsorbed in the gut and circulate back to the liver for further biliary secretion. Therefore, pharmacological inhibition of the ileal apical sodium-dependent BA transporter (ASBT/SLC10A2) may protect against BA-mediated cholestatic liver and bile duct injury. METHODS: Eight week old Mdr2(-/-) (Abcb4(-/-)) mice (model of cholestatic liver injury and sclerosing cholangitis) received either a diet supplemented with A4250 (0.01% w/w) - a highly potent and selective ASBT inhibitor - or a chow diet. Liver injury was assessed biochemically and histologically after 4weeks of A4250 treatment. Expression profiles of genes involved in BA homeostasis, inflammation and fibrosis were assessed via RT-PCR from liver and ileum homogenates. Intestinal inflammation was assessed by RNA expression profiling and immunohistochemistry. Bile flow and composition, as well as biliary and fecal BA profiles were analyzed after 1week of ASBT inhibitor feeding. RESULTS: A4250 improved sclerosing cholangitis in Mdr2(-/-) mice and significantly reduced serum alanine aminotransferase, alkaline phosphatase and BAs levels, hepatic expression of pro-inflammatory (Tnf-α, Vcam1, Mcp-1) and pro-fibrogenic (Col1a1, Col1a2) genes and bile duct proliferation (mRNA and immunohistochemistry for cytokeratin 19 (CK19)). Furthermore, A4250 significantly reduced bile flow and biliary BA output, which correlated with reduced Bsep transcription, while Ntcp and Cyp7a1 were induced. Importantly A4250 significantly reduced biliary BA secretion but preserved HCO3(-) and biliary phospholipid secretion resulting in an increased HCO3(-)/BA and PL/BA ratio. In addition, A4250 profoundly increased fecal BA excretion without causing diarrhea and altered BA pool composition, resulting in diminished concentrations of primary BAs tauro-ß-muricholic acid and taurocholic acid. CONCLUSIONS: Pharmacological ASBT inhibition attenuates cholestatic liver and bile duct injury by reducing biliary BA concentrations in mice.

The chronic kidney disease epidemiology collaboration equation combining creatinine and cystatin C accurately assesses renal function in patients with cirrhosis.

BACKGROUND: Accurate measurement of renal function in cirrhotic patients is still challenging. To find the best test for the determination of the true glomerular filtration rate (GFR) in cirrhotic patients this study prospectively compared measured (m)GFR, the gold standard, with estimated (e)GFR using equations based on serum levels of creatinine and cystatin C. METHODS: GFR was measured by sinistrin clearance using the bolus method in 50 patients with cirrhosis (Child Turcotte Pugh score A, B and C) and 24 age-matched healthy subjects as controls. Measured (m)GFR was compared to eGFR using bias, accuracy 10 % and 30 %, as well as correlation coefficients. RESULTS: Creatinine-based equations generally overestimated GFR in patients with cirrhosis and showed a bias (average difference between mGFR and eGFR) of -40 (CG), -12 (MDRD) and -9 (CKD-EPI-Cr) ml/min/1.73 m(2). Cystatin C-based equations underestimated GFR, especially in patients with Child Turcotte Pugh score C (bias 17 ml/min/1.73 m(2)for CKD-EPI-CysC). Of these equations, the CKD-EPI equation that combines creatinine and cystatin C (CKD-EPI-Cr-CysC) showed a bias of 0.12 ml/min/1.73 m(2) as compared to measured GFR. CONCLUSIONS: The CKD-EPI equation that combines serum creatinine and cystatin C measurements shows the best performance for accurate estimation of GFR in cirrhosis, especially at advanced stages.

Bile acid-induced cholemic nephropathy.

Kidney injury in deeply jaundiced patients became known as cholemic nephropathy. This umbrella term covers impaired renal function in cholestatic patients with characteristic histomorphological changes including intratubular cast formation and tubular epithelial cell injury. Cholemic nephropathy represents a widely underestimated but important cause of kidney dysfunction in patients with cholestasis and advanced liver disease. However, the nomenclature is inconsistent since there are numerous synonyms used; the underlying mechanisms of cholemic nephropathy are not entirely clear, and widely accepted diagnostic criteria are still missing. Consequently, the current article aims to summarize the present knowledge on the clinical and morphological characteristics, available preclinical models, derived potential pathomechanisms, and future diagnostic and therapeutic strategies in cholemic nephropathy. Furthermore, we provide a potential research agenda for this evolving field.

Potential of nor-Ursodeoxycholic Acid in Cholestatic and Metabolic Disorders.

24-nor-ursodeoxycholic acid (norUDCA) is a side-chain shortened derivate of ursodeoxycholic acid (UDCA). Since norUDCA is only ineffectively conjugated with glycine or taurine, it has specific physicochemical and therapeutic properties distinct from UDCA. Nonamidated norUDCA undergoes cholehepatic shunting enabling 'ductular targeting' and inducing a bicarbonate-rich hypercholeresis, with cholangioprotective effects. At the same time it has direct anti-inflammatory, antilipotoxic, anti fibrotic, and antiproliferative properties targeting various liver cell populations. norUDCA appears to be one of the most promising novel treatment approaches targeting the liver and the bile duct system at multifactorial and multicellular levels. This review article is a summary of a lecture given at the XXIII International Bile Acid Meeting (Falk Symposium 194) on 'Bile Acids as Signal Integrators and Metabolic Modulators' held in Freiburg, October 8-9, 2014, and summarizes the recent progress with norUDCA as a novel therapeutic approach in cholestatic and metabolic (liver) disorders.

Evaluation of genome-wide loci of iron metabolism in hereditary hemochromatosis identifies PCSK7 as a host risk factor of liver cirrhosis.

Genome-wide association studies (GWAS) have revealed genetic determinants of iron metabolism, but correlation of these with clinical phenotypes is pending. Homozygosity for HFE C282Y is the predominant genetic risk factor for hereditary hemochromatosis (HH) and may cause liver cirrhosis. However, this genotype has a low penetrance. Thus, detection of yet unknown genetic markers that identify patients at risk of developing severe liver disease is necessary for better prevention. Genetic loci associated with iron metabolism (TF, TMPRSS6, PCSK7, TFR2 and Chr2p14) in recent GWAS and liver fibrosis (PNPLA3) in recent meta-analysis were analyzed for association with either liver cirrhosis or advanced fibrosis in 148 German HFE C282Y homozygotes. Replication of associations was sought in additional 499 Austrian/Swiss and 112 HFE C282Y homozygotes from Sweden. Only variant rs236918 in the PCSK7 gene (proprotein convertase subtilisin/kexin type 7) was associated with cirrhosis or advanced fibrosis (P = 1.02 × 10(-5)) in the German cohort with genotypic odds ratios of 3.56 (95% CI 1.29-9.77) for CG heterozygotes and 5.38 (95% CI 2.39-12.10) for C allele carriers. Association between rs236918 and cirrhosis was confirmed in Austrian/Swiss HFE C282Y homozygotes (P = 0.014; ORallelic = 1.82 (95% CI 1.12-2.95) but not in Swedish patients. Post hoc combined analyses of German/Swiss/Austrian patients with available liver histology (N = 244, P = 0.00014, ORallelic = 2.84) and of males only (N = 431, P = 2.17 × 10(-5), ORallelic = 2.54) were consistent with the premier finding. Association between rs236918 and cirrhosis was not confirmed in alcoholic cirrhotics, suggesting specificity of this genetic risk factor for HH. PCSK7 variant rs236918 is a risk factor for cirrhosis in HH patients homozygous for the HFE C282Y mutation.