Serum metabolic signatures of primary biliary cirrhosis and primary sclerosing cholangitis

Protection against oxidative stress mediated by the Nrf2/Keap1 axis is impaired in Primary Biliary Cholangitis

In response to oxidative stress, nuclear factor (erythroid-derived 2)-like2 (Nrf2) induces expression of cytoprotective genes. The Nrf2 pathway is controlled by microRNAs and Kelch-like ECH-associated protein1 (Keap1). Nrf2 is stabilized when Keap1 is degraded through the autophagy pathway in a p62-dependent manner. The inhibition of autophagy causes protein accumulation, and Keap1 is inactivated by binding to p62. We investigated the role of the Nrf2/Keap1 axis in the amelioration of oxidative stress in primary biliary cholangitis (PBC). Liver specimens from patients with PBC, with (n = 24) or without cirrhosis (n = 14), and from controls (n = 16) were used for molecular analyses. We found that Nrf2 protein levels were elevated in PBC compared to controls, but Nrf2 gene expression was significantly reduced in cirrhotic PBC. Nrf2 target gene products, HO-1 and GCLC proteins, were reduced compared to controls and reduction of Nrf2 gene expression was associated with elevated levels of microRNA-132 and microRNA-34a. Both Keap1 and p62 protein levels were substantially increased in PBC compared to controls. PBC was associated with reduced Nrf2 expression and autophagy deterioration and these impairments were more advanced in patients with cirrhosis. Aberrant Nrf2/Keap1 system integrity may affect self-defence mechanisms against oxidative stress in PBC.

Intestinal microbiota in primary sclerosing cholangitis

PURPOSE OF REVIEW

Alterations of the gut-liver axis have been linked to the pathogenesis of primary sclerosing cholangitis (PSC) since the disease was first described. The purpose of this review is to discuss multiple recent studies on the intestinal microbiota in human PSC and experimental models of this disease.

RECENT FINDINGS

Data are available from eight cross-sectional studies of human PSC, which include a variable number of patients (n = 11-85), material (mucosal or fecal), and microbiota profiling methodology. Despite the heterogeneity of the studies, a pattern of differences is observed that could represent a theme or signature of the PSC gut microbiota, characterized by low diversity and with alterations in multiple bacterial taxa. In experimental models of PSC, re-derivation of animals into germ-free facilities may either aggravate or attenuate the disease, depending on host genetics and putative disease mechanisms (e.g., fibrotic or immune-driven processes, respectively).

SUMMARY

The present data provide a strong rationale to explore the functional consequences of the observed gut microbial alterations and their influence on the pathogenesis in PSC. Studies of gut microbiota as biomarker and treatment target may potentially also lead to early translation into clinical practice.

Impaired Hepatic Adaptation to Chronic Cholestasis induced by Primary Sclerosing Cholangitis

Pathogenesis of primary sclerosing cholangitis (PSC) may involve impaired bile acid (BA) homeostasis. We analyzed expressions of factors mediating enterohepatic circulation of BA using ileal and colonic (ascending and sigmoid) biopsies obtained from patients with PSC with and without ulcerative colitis (UC) and explanted PSC livers. Two-fold increase of BA-activated farnesoid X receptor (FXR) protein levels were seen in ascending and sigmoid colon of PSC patients with correspondingly decreased apical sodium-dependent BA transporter (ASBT) gene expression. This was associated with increased OSTβ protein levels in each part of analyzed gut. An intestinal fibroblast growth factor (FGF19) protein expression was significantly enhanced in ascending colon. Despite increased hepatic nuclear receptors (FXR, CAR, SHP), and FGF19, neither CYP7A1 suppression nor CYP3A4 induction were observed. The lack of negative regulation of BA synthesis may be accountable for lower levels of cholesterol observed in PSC in comparison to primary biliary cholangitis (PBC). In conclusion, chronic cholestasis in PSC induces adaptive changes in expression of BA transporters and FXR in the intestine. However hepatic impairment of expected in chronic cholestasis downregulation of CYP7A1 and upregulation of CYP3A4 may promote BA-induced liver injury in PSC.

Metabonomic window into hepatitis B virus-related hepatic diseases

Metabonomics has recently been widely used to discover the pathogenesis and find potential metabolic markers with high sensitivity and specificity. Furthermore, it develops new diagnosis and treatment methods, increases early phase diagnosis rates of certain diseases and provides a new basis for targeted therapy. This review mainly analyzes the research progress of the metabonomics of hepatitis B virus (HBV)-related hepatic diseases, hoping to discover some potential metabolic markers for identification of HBV-related hepatic diseases from other etiologies and for HBV-related hepatitis, liver cirrhosis and hepatocellular carcinoma. This can contribute to early discovery, diagnosis and treatment, eventually increasing the survival rate of HBV-related hepatic diseases.

Colonic mucosal gene expression and genotype in irritable bowel syndrome patients with normal or elevated fecal bile acid excretion

The mucosal gene expression in rectosigmoid mucosa (RSM) in irritable bowel syndrome with diarrhea (IBS-D) is unknown. Our objectives were, first, to study mRNA expression [by RT(2) PCR of 19 genes pertaining to tight junctions, immune activation, intestinal ion transport and bile acid (BA) homeostasis] in RSM in IBS-D patients (n = 47) and healthy controls (n = 17) and study expression of a selected protein (PDZD3) in 10 IBS-D patients and 4 healthy controls; second, to assess RSM mRNA expression according to genotype and fecal BA excretion (high ≥ 2,337 μmol/48 h); and third, to determine whether genotype or mucosal mRNA expression is associated with colonic transit or BA parameters. Fold changes were corrected for false detection rate for 19 genes studied (P < 0.00263). In RSM in IBS-D patients compared with controls, mRNA expression of GUC2AB, PDZD3, and PR2Y4 was increased, whereas CLDN1 and FN1 were decreased. One immune-related gene was upregulated (C4BP4) and one downregulated (CCL20). There was increased expression of a selected ion transport protein (PDZD3) on immunohistochemistry and Western blot in IBS-D compared with controls (P = 0.02). There were no significant differences in mucosal mRNA in 20 IBS-D patients with high compared with 27 IBS-D patients with normal BA excretion. GPBAR1 (P < 0.05) was associated with colonic transit. We concluded that mucosal ion transport mRNA (for several genes and PDZD3 protein) is upregulated and barrier protein mRNA downregulated in IBS-D compared with healthy controls, independent of genotype. There are no differences in gene expression in IBS-D with high compared with normal fecal BA excretion.

Urine and serum metabolomic profiling reveals that bile acids and carnitine may be potential biomarkers of primary biliary cirrhosis

In order to provide non-invasive, reliable and sensitive laboratory parameters for the diagnosis of primary biliary cirrhosis (PBC), metabolic technology of ultraperformance liquid chromatography coupled with quadrupole-time-of-flight mass spectrometry (UPLC/Q-TOF MS) was used to compare small molecule metabolites in blood and urine from patients with PBC and healthy controls. We then screened for bio-markers in the blood and urine of the patients with PBC. Data were processed by Bruker ProfileAnalysis metabonomic software and imported to SIMCA-P software, which utilized principal component analysis (PCA) to create models of patients with PBC and healthy controls. In total, 18 urinary markers were found and the levels of 11 of these urinary markers were elevated in the patients with PBC, whereas the levels of the remaining 7 markers were lower in the PBC group compared to the control group. We also identified 20 blood-based biomarkers in the patients with PBC and the levels of 9 of these markers were higher in the PBC group, whereas the levels of the remaining 11 markers were lower in the patients with PBC compared to the controls. Among these biomarkers, the levels of bile acids increased with the progression of PBC, while the levels of carnitines, such as propionyl carnitine and butyryl carnitine, decreased with the progression of PBC. In conclusion, the findings of the present study suggest that the circulating levels of bile acids and carnitine are differentially altered in patients with PBC.