Effects of intestine-specific deletion of FGF15 on the development of fatty liver disease with vertical sleeve gastrectomy.

BACKGROUND: Vertical sleeve gastrectomy (SGx) is a type of bariatric surgery to treat morbid obesity and metabolic dysfunction-associated steatotic liver disease (MASLD). The molecular mechanisms of SGx to improve MASLD are unclear, but increased bile acids (BAs) and FGF19 (mouse FGF15) were observed. FGF15/19 is expressed in the ileum in response to BAs and is critical in not only suppressing BA synthesis in the liver but also promoting energy expenditure. We hypothesized the reduction of obesity and resolution of MASLD by SGx may be mediated by FGF15/19. METHODS: First, we conducted hepatic gene expression analysis in obese patients undergoing SGx, with the results showing increased expression of FGF19 in obese patients' livers. Next, we used wild-type and intestine-specific Fgf15 knockout mice (Fgf15ile-/-) to determine the effects of FGF15 deficiency on improving the metabolic effects. RESULTS: SGx improved metabolic endpoints in both genotypes, evidenced by decreased obesity, improved glucose tolerance, and reduced MASLD progression. However, Fgf15ile-/- mice showed better improvement compared to wild-type mice after SGx, suggesting that other mediators than FGF15 are also responsible for the beneficial effects of FGF15 deficiency. Further gene expression analysis in brown adipose tissue suggests increased thermogenesis. CONCLUSIONS: FGF15 deficiency, the larger BA pool and higher levels of secondary BAs may increase energy expenditure in extrahepatic tissues, which may be responsible for improved metabolic functions following SGx.

A Giant Childhood Mesenteric Lipoblastoma With Extensive Maturation.

Abdominal lipoblastomas are uncommon soft tissue tumors in children and rarely arise from the mesentery. Due to intraabdominal location and slow growth, these masses can go unnoticed for long periods of time and often found on surgical exploration. We present a case of a 12-year-old male with years of abdominal distension accompanied by new onset early satiety that was found to have an intra-abdominal mass. He underwent an exploratory laparotomy revealing a large 33 x 27 x 15 cm rubbery mesenteric mass displacing the entire intra-abdominal contents, connected by a single vascular pedicle and encasing a loop of small intestine. The mass was resected and the patient did well without signs of recurrence. Histology confirmed the presence of mature adipocytes but on further cytogenetic analysis, a translocation between chromosomes 2 and 8 at the 12q arm was detected, which is often associated with lipoblastomas. This case represents the one of the largest mesenteric lipoblastomas that matured extensively to lipoma-like histology at the time of surgical resection.

Enhanced alcoholic liver disease in mice with intestine-specific farnesoid X receptor deficiency.

Alcoholic fatty liver disease (AFLD) is one of the major causes of liver morbidity and mortality worldwide. We have previously shown that whole-body, but not hepatocyte-specific, deficiency of farnesoid X receptor (FXR) in mice worsens AFLD, suggesting that extrahepatic FXR deficiency is critical for AFLD development. Intestinal FXR is critical in suppressing hepatic bile acid (BA) synthesis by inducing fibroblast growth factor 15 (FGF15) in mice and FGF19 in humans. We hypothesized that intestinal FXR is critical for reducing AFLD development in mice. To test this hypothesis, we compared the AFLD severity in wild type (WT) and intestine-specific Fxr knockout (FXRInt-/-) mice following treatment with control or ethanol-containing diet. We found that FXRInt-/- mice were more susceptible to ethanol-induced liver steatosis and inflammation, compared with WT mice. Ethanol treatment altered the expression of hepatic genes involved in lipid and BA homeostasis, and ethanol detoxification. Gut FXR deficiency increased intestinal permeability, likely due to reduced mucosal integrity, as revealed by decreased secretion of Mucin 2 protein and lower levels of E-cadherin protein. In summary, intestinal FXR may protect AFLD development by maintaining gut integrity.

Direct and Indirect Effects of Fibroblast Growth Factor (FGF) 15 and FGF19 on Liver Fibrosis Development.

Farnesoid X receptor (FXR) induces fibroblast growth factor 15 (FGF15; human ortholog FGF19) in the gut to potently inhibit bile acid (BA) synthesis in the liver. FXR activation in hepatic stellate cells (HSCs) reduces liver fibrosis (LF). Fgf15-/- mice develop attenuated LF, but the underlying mechanisms for this protection are unclear. We hypothesized that FGF15/19 functions as a profibrotic mediator or mitogen to HSCs and increased BAs in Fgf15-/- mice leads to enhanced FXR activation in HSCs, subsequently reducing fibrogenesis. In this study, complimentary in vivo and in vitro approaches were used: (1) CCl4 -induced LF model in wild type (WT), Fgf15-/- , and Fgf15 transgenic (TG) mice with BA levels modulated by feeding cholestyramine- or cholic acid-containing diets; (2) analysis of primary HSCs isolated from WT and Fgf15-/- mice; and (3) treatment of a human HSC line, LX-2, with FXR activators and/or recombinant FGF19 protein. The results showed that Fgf15-/- mice had lower basal collagen expression, which was increased by BA sequestration. CCl4 induced fibrosis with similar severity in all genotypes; however, cholestyramine increased fibrosis severity only in Fgf15-/- mice. HSCs from Fgf15-/- mice showed increased FXR activity and reduced expression of profibrotic mediators. In LX-2 cells, FXR activation increased peroxisome proliferator-activated receptor gamma activity and reduced proliferation. FGF19 activated both signal transducer and activator of transcription 3 and c-Jun N-terminal kinase pathways and reduced nuclear factor kappa-light-chain-enhancer of activated B cells signaling without increasing fibrogenic gene expression or cell proliferation. Conclusion: FGF15/19 does not act as a direct profibrotic mediator or mitogen to HSCs in our models, and the protection against fibrosis by FGF15 deficiency may be mediated through increased BA activation of FXR in HSCs.

FXR deficiency alters bile acid pool composition and exacerbates chronic alcohol induced liver injury.

Recent studies have investigated the roles of FXR deficiency in the pathogenesis of alcoholic liver disease (ALD). However, the underlying molecular mechanisms remain unclear. In this study, FXR knockout (FXR-/-) and wild-type (WT) mice were subjected to chronic-plus-binge alcohol feeding to study the effect of FXR deficiency on ALD development. The degree of liver injury was greater in FXR-/- mice compared to WT mice. Ethanol feeding enhanced hepatic steatosis in FXR-/- mice, accompanied by decreased mRNA levels of Pparα and Srebp-1c. The expression of Lcn2 was increased by ethanol treatment, despite unchanged expression of pro-inflammatory cytokines Tnfα, Il6 and Il-1ß. Furthermore, ethanol treatment altered bile acid (BA) homeostasis to a greater extent in FXR-/- mice, as well as serum and hepatic BA pool composition. The mRNA levels of hepatic Cyp7a1 and Shp, as well as intestinal Fgf15, were decreased in WT mice with ethanol feeding, which were further reduced in FXR-/- mice. Levels of both primary and secondary BAs were markedly elevated in FXR-/- mice, which were further increased after ethanol treatment. Moreover, hepatic MAPK signaling pathways were disturbed presumably by increased hepatic BA levels. In summary, FXR deficiency increased hepatic steatosis and altered BA pool composition, contributing to worsened liver toxicity.

FXR deletion in hepatocytes does not affect the severity of alcoholic liver disease in mice.

Emerging evidence has shown that FXR activation ameliorates the development of alcoholic liver diseases (ALD) while whole-body deficiency of FXR in mice leads to more severe ALD. However, it's unknown whether the enhanced susceptibility to ALD development in FXR-/- mice is due to deficiency of hepatic FXR or increased toxicity secondary to increased bile acid (BA) levels. Hepatocyte-specific FXR knockout mice (FXRhep-/-) present similar BA levels compared to wild-type mice, and are therefore a useful model to study a direct role of hepatic FXR in ALD development. FXRhep-/- mice were subject to an ALD model with chronic plus binge drinking of alcohol to determine the effects of hepatic FXR deficiency on ALD development. The FXRhep-/- mice showed an altered expression of genes involved in BA and lipid homeostasis with alcohol treatment. Despite a slightly increased trend in hepatic lipid deposition and collagen accumulation in FXRhep-/- mice, there were no significant differences in the severity of steatosis, inflammation, or fibrosis between WT and FXRhep-/- mice. Therefore, these findings indicate that FXR deficiency in hepatocytes might only play a minor role in ALD development. Deficiency of FXR in other non-hepatic tissues and/or increased BA levels resultant from whole-body FXR deficiency might be responsible for more severe ALD development.

Fibroblast Growth Factor 15-Dependent and Bile Acid-Independent Promotion of Liver Regeneration in Mice.

The role of intestine-derived factors in promoting liver regeneration after partial hepatectomy (PHx) are not entirely known, but bile acids (BAs) and fibroblast growth factor 15 (Fgf15) that is highly expressed in the mouse ileum could promote hepatocyte proliferation. Fgf15 strongly suppresses the synthesis of BAs, and emerging evidence indicates that Fgf15 is important for liver regeneration. The mechanisms by which Fgf15 promotes liver regeneration are unclear, but Fgf15 may do so indirectly by reducing BA levels and/or directly by promoting cell proliferation. However, it remains undetermined whether these two mechanisms are independent or integrated. In this study, we aimed to clarify these relationships by generating Fgf15 Tet-Off, transgenic mice (Fgf15 Tg) that had very low BA levels as a result from overexpressed Fgf15-mediated suppression of BA synthesis. Compared with wild-type mice, the Fgf15 Tg mice showed increased hepatocyte proliferation even without surgery, and a further induction of the genes in cell-cycle progression after PHx. Moreover, overexpression of Fgf15 by adeno-associated virus (AAV)-Fgf15 transduction or treatment with the recombinant Fgf15 protein led to increased cell proliferation in vivo. Furthermore, Fgf15 Tg mice exhibited an earlier and greater activation of mitogen-activated protein kinase, signal transducer and activator of transcription 3, and NF-κB signaling pathways in the priming stage, and a disruption of the hippo signaling pathway in the termination stage of liver regeneration. Conclusion: Direct in vivo evidence demonstrates that Fgf15 is critical in stimulating the phases of priming and termination of liver regeneration that are critical for cell survival and liver-size determination, independent of BA levels. (Hepatology 2018; 00:000-000).

Negative HBcAg in immunohistochemistry assay of liver biopsy is a predictive factor for the treatment of patients with nucleos(t)ide analogue therapy.

The hepatitis B core antigen (HBcAg) is an important target for antiviral response in chronic hepatitis B (CHB) patients. However, the correlation between HBcAg in the hepatocyte nucleus and nucleos(t)ide analogue (NA) therapeutic response is unclear. We sought to evaluate the role of HBcAg by analysing liver biopsies for viral response in NA-naïve hepatitis B e antigen (HBeAg) positive (+) CHB patients via immunohistochemistry (IHC). A total of 48 HBcAg-negative (-) patients and 48 HBcAg (+) patients with matching baseline characteristics were retrospectively analysed for up to 288 weeks. Virological response (VR) rates of patients in the HBcAg (-) group were significantly higher at week 48 and 96 than the HBcAg (+) group (77.1% versus 45.8% at week 48, respectively, P = 0.002 and 95.3% versus 83.3% at week 96, respectively, P = 0.045). The serological negative conversion rate of HBeAg was significantly higher in the HBcAg (-) than in the HBcAg (+) group from week 96 to 288 (35.4 % versus 14.6% at week 96, respectively, P = 0.018; 60.4% versus 14.6%, respectively, P < 0.001 at week 144; 72.9% versus 35.4%, respectively, P < 0.001 at week 288). The cumulative frequencies of VR and lack of HBeAg were higher in the HBcAg (-) group (both P < 0.05). Binary logistic regression analysis showed that HBcAg (-) was the predictor for the lack of HBeAg (OR 4.482, 95% CI: 1.58-12.68). In summary, the absence of HBcAg in the hepatocyte nucleus could be an independent predictor for HBeAg seroconversion rates during NA-naïve treatment in HBeAg (+) CHB patients.

The role of bile acids in nonalcoholic fatty liver disease and nonalcoholic steatohepatitis.

Nonalcoholic fatty liver disease is growing in prevalence worldwide. It is marked by the presence of macrosteatosis on liver histology but is often clinically asymptomatic. However, it can progress into nonalcoholic steatohepatitis which is a more severe form of liver disease characterized by inflammation and fibrosis. Further progression leads to cirrhosis, which predisposes patients to hepatocellular carcinoma or liver failure. The mechanism by which simple steatosis progresses to steatohepatitis is not entirely clear. However, multiple pathways have been proposed. A common link amongst many of these pathways is disruption of the homeostasis of bile acids. Other than aiding in the absorption of lipids and lipid-soluble vitamins, bile acids act as ligands. For example, they bind to farnesoid X receptor, which is critically involved in many of the pathways responsible for maintaining bile acid, glucose, and lipid homeostasis. Alterations to these pathways can lead to dysregulation of energy balance and increased inflammation and fibrosis. Repeated insults over time may be the key to development of steatohepatitis. For this reason, current drug therapies target aspects of these pathways to try to reduce and halt inflammation and fibrosis. This review will focus on the role of bile acids in these various pathways and how changes in these pathways may result in steatohepatitis. While there is no approved pharmaceutical treatment for either hepatic steatosis or steatohepatitis, this review will also touch upon the multitude of potential therapies.

Peliosis hepatis in a child with myotubular myopathy: successful treatment using hepatic artery embolization.

Peliosis hepatis (PH) is a rare condition characterized by multiple blood-filled spaces within the hepatic parenchyma that can lead to fatal hemorrhage. There is no consensus on the best treatment algorithm for PH, and therapy is directed at removing the potential causative agent with operative intervention when necessary. Here we present the first known case of PH in a child with myotubular myopathy who was successfully treated with angiography and hepatic artery embolization as a first line therapy, without the need for operative intervention. Awareness of this condition and the available treatment modalities may lead to favorable outcomes in future cases.

Acute colonoscopy-induced splenic rupture presenting to the emergency department.

Splenic rupture due to colonoscopy is a rarely reported event in the emergency medicine literature. Patients experiencing such an occurrence are likely to report to the emergency department. This paper documents an 84-year-old female who presented to the emergency department with abdominal pain and nausea less than 24 hours following a colonoscopy. An abdominal ultrasound revealed splenomegaly and free fluid. An abdominal computed tomography was significant for a splenic laceration. She underwent radiologic guided embolization and recovered without incident. Emergency medicine physicians need to consider splenic rupture as a differential in patients presenting after colonoscopy with abdominal pain.

Cultivation-dependent characterization of bacterial diversity from British Columbia forest soils subjected to disturbance.

Bacteria from forest surface organic matter and mineral soil horizons were cultivated using four methods and characterized by fatty acid methyl ester (FAME) analysis. Soil samples from a British Columbia Ministry of Forests Long-Term Soil Productivity (LTSP) installation were collected during winter and summer from two disturbance treatments (whole-tree harvesting with no soil compaction (plot N) and whole-tree harvesting plus complete surface organic matter removal with heavy soil compaction (plot S)) and from an unlogged reference plot (REF). Seventy-five percent of 1795 bacterial isolates were affiliated with 42 genera representing beta- and gamma-Proteobacteria, Actinobacteria, the Bacillus/Clostridium group, and the Cytophaga-Flexibacter-Bacteroides group. Approximately half of the culture collection represented genetic diversity confined to four bacterial genera: Pseudomonas, Bacillus, Paenibacillus, and Arthrobacter. A significantly higher proportion of bacterial isolates belonging to Actinobacteria, and the member genus Arthrobacter, were isolated from plot S soil samples compared with soil samples from plots N and REF. Twenty-five percent of bacterial isolates were not conclusively identified to genus with FAME analysis. Sherlock Tracker cluster analysis and partial 16S rRNA gene sequence analysis enabled classification of a subset of these isolates.

Molecular characterization of bacterial diversity from British Columbia forest soils subjected to disturbance.

Bacteria from forest soils were characterized by DNA sequence analysis of cloned 16S rRNA gene fragments (16S clones). Surface organic matter and mineral soil samples from a British Columbia Ministry of Forests Long-Term Soil Productivity (LTSP) installation were collected during winter and summer from two disturbance treatments: whole-tree harvesting with no soil compaction (plot N) and whole-tree harvesting plus complete surface organic matter removal with heavy soil compaction (plot S). Phylogenetic analyses revealed that 87% of 580 16S clones were classified as Proteobacteria, Actinobacteria, Acidobacterium, Verrucomicrobia, Bacillus/Clostridium group, Cytophaga-Flexibacter-Bacteroides group, green nonsulfur bacteria, Planctomyces, and candidate divisions TM6 and OP10. Seventy-five 16S clones could not be classified into known bacterial divisions, and five 16S clones were related to chloroplast DNA. Members of Proteobacteria represented 46% of the clone library. A higher proportion of 16S clones affiliated with y-Proteobacteria were from plot N compared with plot S. 16S rRNA gene fragments amplified with Pseudomonas-specific primers and cloned (Ps clones) were examined from mineral-soil samples from plots N and S from three LTSP installations. A significantly greater proportion of sequenced Ps clones from plot N contained Pseudomonas 16S rRNA gene fragments compared with Ps clones from plot S.

Molecular characterization of bacterial diversity in Lodgepole pine (Pinus contorta) rhizosphere soils from British Columbia forest soils differing in disturbance and geographic source.

Rhizosphere bacteria from Lodgepole pine (Pinus contorta) seedlings were characterized from forest soils which differed in disturbance and geographic source. Soil disturbance treatments included whole-tree harvesting with and without heavy soil compaction and whole-tree harvesting with complete surface organic matter removal and heavy soil compaction from British Columbia (BC) Ministry of Forests Long-Term Soil Productivity installations in three biogeoclimatic subzones in central BC, Canada. Bacterial community members were characterized by DNA sequence analysis of 16S rRNA gene fragments following direct DNA isolation from soil, polymerase chain reaction amplification and cloning. Phylogenetic analyses revealed that 85% of 709 16S rDNA clones were classified as alpha-, beta-, gamma-, and delta-Proteobacteria, Actinobacteria, Cytophaga-Flexibacter-Bacteroides group, Acidobacterium, Verrucomicrobia, and candidate divisions OP10 and TM6. Members of the Proteobacteria and Acidobacterium represented 55% and 19% of the clone library, respectively, whereas the remaining bacterial divisions each comprised less than 4% of the clone library. One hundred and six 16S rDNA clones could not be classified into known bacterial divisions. No significant differences were detected for soil disturbance treatment or site effects on the proportions of 16S rDNA clones affiliated with Proteobacteria and Acidobacterium. Phylogenetic analyses revealed that it was common for 16S rRNA gene fragments from different soil disturbance treatments and geographic locations to be closely related.