Regional unit definition for the nucleus of comet 67P/Churyumov-Gerasimenko on the SHAP7 model

Open Acces publication. This article is available under the Creative Commons CC-BY-NC-ND license and permits non-commercial use of the work as published, without adaptation or alteration provided the work is fully attributed.The previously defined regions on the nucleus of comet 67P/Churyumov-Gerasimenko have been mapped back onto the 3D SHAP7 model of the nucleus (Preusker et al., 2017). The resulting regional definition is therefore self-consistent with boundaries that are well defined in 3 dimensions. The facets belonging to each region are provided as supplementary material. The shape model has then been used to assess inhomogeneity of nucleus surface morphology within individual regions. Several regions show diverse morphology. We propose sub-division of these regions into clearly identifiable units (sub-regions) and a comprehensive table is provided. The surface areas of each sub-region have been computed and statistics based on grouping of unit types are provided. The roughness of each region is also provided in a quantitative manner using a technique derived from computer graphics applications. The quantitative method supports the sub-region definition by showing that differences between sub-regions can be numerically justified.© 2018 The AuthorsThe team from the University of Bern is supported through the Swiss National Science Foundation and through the NCCR PlanetS. The project has also received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 686709. This work was supported by the Swiss State Secretariat for Education, Research and Innovation (SERI) under contract number 16.0008-2

Regional unit definition for the nucleus of comet 67P/Churyumov-Gerasimenko on the SHAP7 model

The previously defined regions on the nucleus of comet 67P/Churyumov-Gerasimenko have been mapped back onto the 3D SHAP7 model of the nucleus (Preusker et al., 2017). The resulting regional definition is therefore self-consistent with boundaries that are well defined in 3 dimensions. The facets belonging to each region are provided as supplementary material. The shape model has then been used to assess inhomogeneity of nucleus surface morphology within individual regions. Several regions show diverse morphology. We propose sub-division of these regions into clearly identifiable units (sub-regions) and a comprehensive table is provided. The surface areas of each sub-region have been computed and statistics based on grouping of unit types are provided. The roughness of each region is also provided in a quantitative manner using a technique derived from computer graphics applications. The quantitative method supports the sub-region definition by showing that differences between sub-regions can be numerically justified

Risk factors and outcomes associated with recurrent autoimmune hepatitis following liver transplantation

Background & Aims: Autoimmune hepatitis can recur after liver transplantation (LT), though the impact of recurrence on patient and graft survival has not been well characterized. We evaluated a large, international, multicenter cohort to identify the probability and risk factors associated with recurrent AIH and the association between recurrent disease and patient and graft survival.Methods: We included 736 patients (77% female, mean age 42 +/- 1 years) with AIH who underwent LT from January 1987 through June 2020, among 33 centers in North America, South America, Europe and Asia. Clinical data before and after LT, biochemical data within the first 12 months after LT, and immunosuppression after LT were analyzed to identify patients at higher risk of AIH recurrence based on histological diagnosis.Results: AIH recurred in 20% of patients after 5 years and 31% after 10 years. Age at LT <= 42 years (hazard ratio [HR] 3.15; 95% CI 1.22-8.16; p = 0.02), use of mycophenolate mofetil post-LT (HR 3.06; 95% CI 1.39-6.73; p = 0.005), donor and recipient sex mismatch (HR 2.57; 95% CI 1.39-4.76; p = 0.003) and high IgG pre-LT (HR 1.04; 95% CI 1.01-1.06; p = 0.004) were associated with higher risk of AIH recurrence after adjusting for other confounders. In multivariate Cox regression, recurrent AIH (as a time-dependent covariate) was significantly associated with graft loss (HR 10.79, 95% CI 5.37-21.66, p <0.001) and death (HR 2.53, 95% CI 1.48-4.33, p = 0.001).Conclusion: Recurrence of AIH following transplant is frequent and is associated with younger age at LT, use of mycophenolate mofetil post-LT, sex mismatch and high IgG pre-LT. We demonstrate an association between disease recurrence and impaired graft and overall survival in patients with AIH, highlighting the importance of ongoing efforts to better characterize, prevent and treat recurrent AIH.Lay summary: Recurrent autoimmune hepatitis following liver transplant is frequent and is associated with some recipient features and the type of immunosuppressive medications use. Recurrent autoimmune hepatitis negatively affects outcomes after liver transplantation. Thus, improved measures are required to prevent and treat this condition. (C) 2022 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.Cellular mechanisms in basic and clinical gastroenterology and hepatolog

Analysis of ileal sodium/bile acid cotransporter and related nuclear receptor genes in a family with multiple cases of idiopathic bile acid malabsorption

The etiology of most cases of idiopathic bile acid malabsorption (IBAM) is unknown. In this study, a Swedish family with bile acid malabsorption in three consecutive generations was screened for mutations in the ileal apical sodium-bile acid cotransporter gene (ASBT; gene symbol, SLC10A2) and in the genes for several of the nuclear receptors known to be important for ASBT expression: the farnesoid X receptor (FXR) and peroxisome proliferator activated receptor alpha (PPAR\u3b1). The patients presented with a clinical history of idiopathic chronic watery diarrhea, which was responsive to cholestyramine treatment and consistent with IBAM. Bile acid absorption was determined using 75Se-homocholic acid taurine (SeHCAT); bile acid synthesis was estimated by measuring the plasma levels of 7\u3b1-hydroxy-4-cholesten-3-one (C4). The ASBT, FXR, and PPAR\u3b1 genes in the affected and unaffected family members were analyzed using single stranded conformation polymorphism (SSCP), denaturing HPLC, and direct sequencing. No ASBT mutations were identified and the ASBT gene did not segregate with the bile acid malabsorption phenotype. Similarly, no mutations or polymorphisms were identified in the FXR or PPAR\u3b1 genes associated with the bile acid malabsorption phenotype. These studies indicate that the intestinal bile acid malabsorption in these patients cannot be attributed to defects in ASBT. In the absence of apparent ileal disease, alternative explanations such as accelerated transit through the small intestine may be responsible for the IBAM

Tetrahydroxylated bile acids improve cholestatic liver and bile duct injury in the Mdr2(-/-) mouse model of sclerosing cholangitis via immunomodulatory effects

Bile salt export pump (Bsep) (Abcb11)(-/-) mice are protected from acquired cholestatic injury due to metabolic preconditioning with a hydrophilic bile acid (BA) pool with formation of tetrahydroxylated bile acids (THBAs). We aimed to explore whether loss of Bsep and subsequent elevation of THBA levels may have immunomodulatory effects, thus improving liver injury in the multidrug resistance protein 2 (Mdr2) (Abcb4)(-/-) mouse. Cholestatic liver injury in Mdr2(-/-)Bsep(-/-) double knockout (DKO), Mdr2(-/-), Bsep(-/-), and wild-type mice was studied for comparison. Mdr2(-/-) mice were treated with a THBA (3 alpha,6 alpha,7 alpha,12 alpha-Tetrahydroxycholanoic acid). RNA/protein expression of inflammatory/fibrotic markers were investigated. Serum BA-profiling was assessed by ultra-performance liquid chromatography tandem mass spectrometry. Hepatic immune cell profile was quantified by flow cytometric analysis (FACS). In vitro, the THBA effect on chenodeoxycholic acid (CDCA)-induced inflammatory signaling in hepatocyte and cholangiocytes as well as lipopolysaccharide (LPS)/interferon-gamma (IFN-gamma)-induced macrophage activation was analyzed. In contrast to Mdr2(-/-), DKO mice showed no features of sclerosing cholangitis. Sixty-seven percent of serum BAs in DKO mice were polyhydroxylated (mostly THBAs), whereas Mdr2(-/-) mice did not have these BAs. Compared with Mdr2(-/-), DKO animals were protected from hepatic inflammation/fibrosis. THBA feeding in Mdr2(-/-) mice improved liver injury. FACS analysis in DKO and Mdr2(-/-) THBA-fed mice showed changes of the hepatic immune cell profile towards an anti-inflammatory pattern. Early growth response 1 (EGR1) protein expression was reduced in DKO and in Mdr2(-/-) THBA-fed mice compared with Mdr2(-/-) control mice. In vitro, THBA-reduced CDCA induced EGR1 protein and mRNA expression of inflammatory markers in hepatocytes and cholangiocytes. LPS/IFN-gamma-induced macrophage activation was ameliorated by THBA. THBAs repress EGR1-related key pro-inflammatory pathways. Conclusion: THBA and their downstream targets may represent a potential treatment strategy for cholestatic liver diseases

Inhibition of MAP4K4 signaling initiates metabolic reprogramming to protect hepatocytes from lipotoxic damage.

The primary hepatic consequence of obesity is non-alcoholic fatty liver disease (NAFLD), affecting about 25% of the global adult population. Non-alcoholic steatohepatitis (NASH) is a severe form of NAFLD characterized by liver lipid accumulation, inflammation, and hepatocyte ballooning, with a different degree of hepatic fibrosis. In the light of rapidly increasing prevalence of NAFLD and NASH, there is an urgent need for improved understanding of the molecular pathogenesis of these diseases. The aim of this study was to decipher the possible role of STE20-type kinase MAP4K4 in the regulation of hepatocellular lipotoxicity and susceptibility to NAFLD. We found that MAP4K4 mRNA expression in human liver biopsies was positively correlated with key hallmarks of NAFLD (i.e., liver steatosis, lobular inflammation, hepatocellular ballooning, and fibrosis). We also found that the silencing of MAP4K4 suppressed lipid deposition in human hepatocytes by stimulating β-oxidation and triacylglycerol secretion, while attenuating fatty acid influx and lipid synthesis. Furthermore, downregulation of MAP4K4 markedly reduced the glycolysis rate and lowered incidences of oxidative/endoplasmic reticulum stress. In parallel, we observed suppressed JNK and ERK activation and increased AKT phosphorylation in MAP4K4-deficient hepatocytes. Together, these results provide the first experimental evidence supporting the potential involvement of STE20-type kinase MAP4K4 as a component of the hepatocellular lipotoxic milieu promoting NAFLD susceptibility

Serine/threonine protein kinase 25 antisense oligonucleotide treatment reverses glucose intolerance, insulin resistance, and nonalcoholic fatty liver disease in mice.

Nonalcoholic fatty liver disease (NAFLD) contributes to the pathogenesis of type 2 diabetes and cardiovascular disease, and patients with nonalcoholic steatohepatitis (NASH) are also at risk of developing cirrhosis, liver failure, and hepatocellular carcinoma. To date, no specific therapy exists for NAFLD/NASH, which has been recognized as one of the major unmet medical needs of the twenty-first century. We recently identified serine/threonine protein kinase (STK)25 as a critical regulator of energy homeostasis and NAFLD progression. Here, we investigated the effect of antisense oligonucleotides (ASOs) targeting on the metabolic and molecular phenotype of mice after chronic exposure to dietary lipids. We found that ASOs efficiently reversed high-fat diet-induced systemic hyperglycemia and hyperinsulinemia, improved whole-body glucose tolerance and insulin sensitivity, and ameliorated liver steatosis, inflammatory infiltration, apoptosis, hepatic stellate cell activation, and nutritional fibrosis in obese mice. Moreover, ASOs suppressed the abundance of liver acetyl-coenzyme A carboxylase (ACC) protein, a key regulator of both lipid oxidation and synthesis, revealing the likely mechanism underlying repression of hepatic fat accumulation by ASO treatment. We also found that STK25 protein levels correlate significantly and positively with NASH development in human liver biopsies, and several common nonlinked single-nucleotide polymorphisms in the human gene are associated with altered liver fat, supporting a critical role of STK25 in the pathogenesis of NAFLD in humans. : Preclinical validation for the metabolic benefit of pharmacologically inhibiting STK25 in the context of obesity is provided. Therapeutic intervention aimed at reducing STK25 function may provide a new strategy for the treatment of patients with NAFLD, type 2 diabetes, and related complex metabolic diseases

Ring Trial on Quantitative Assessment of Bile Acids Reveals a Method- and Analyte-Specific Accuracy and Reproducibility

Bile acids are a key mediator of the molecular microbiome-host interaction, and various mass spectrometry-based assays have been developed in the recent decade to quantify a wide range of bile acids. We compare existing methodologies to harmonize them. Methodology for absolute quantification of bile acids from six laboratories in Europe were compared for the quantification of the primary bile acids cholic acid (CA) and chenodeoxycholic acid (CDCA) and conjugated products glycocholic acid (GCA) and taurocholic acid (TCA). For the bacterially modified secondary bile acids, the quantification of deoxycholic acid (DCA) and lithocholic acid (LCA) was compared. For the murine bile acids, we used the primary muricholic acids (alpha-MCA and, beta-MCA) and the intestinally produced secondary bile acid muricholic (omega-MCA). The standards were spiked into methanol:water (1:1) mix as well as in human and murine serum at either low concentration range (150-3000 nM) or high concentration range (1500-40,000 nM). The precision was better for higher concentrations. Measurements for the hydrophobic unconjugated bile acids LCA and omega-MCA were the most challenging. The quality assessments were generally very similar, and the comprehensive analyses demonstrated that data from chosen locations can be used for comparisons between studies