IL-1ß knockout increases the intestinal abundancy of Akkermansia muciniphila.

The proinflammatory cytokine interleukin-1ß (IL-1ß) is known to be upregulated in patients suffering from metabolic syndrome. IL-1ß contributes to insulin resistance in obesity and type 2 diabetes, yet its influence on the intestinal microbiome is incompletely understood. The data presented here demonstrate that mice genetically deficient in IL-1ß show a specific alteration of intestinal colonisation of a small group of bacteria. Especially Akkermansia muciniphila, a bacterium reported to be inversely associated with obesity, diabetes, cardiometabolic diseases and low-grade inflammation, showed increased colonisation in IL-1ß knockout mice. In comparative microarray analysis from mucus scrapings of the colon mucosa of IL-1ß knockout and wildtype mice, angiogenin 4 mRNA was strongly reduced in IL-1ß knockout animals. Since the presence of angiogenin 4 in the culture medium showed a significant growth inhibition on A. muciniphila which was not detectable for other bacteria tested, IL-1ß induced expression of angiogenin 4 is a strong candidate to be responsible for the IL-1ß induced suppression of A. muciniphila colonisation. Thus, the data presented here indicate that IL-1ß might be the lacking link between inflammation and suppression of A. muciniphila abundance as observed in a variety of chronic inflammatory disorders.

Pathological features of primary sclerosing cholangitis identified by bile proteomic analysis.

Primary sclerosing cholangitis (PSC) is a chronic cholestatic liver disease of unknown origin. Previous bile proteomic analyses in patients with PSC have revealed changes in disease activity specific to malignant transformation. In this study, we established a reference bile duct-derived bile proteome for PSC that can be used to evaluate biliary pathophysiology. Samples were collected from patients with PSC or with choledocholithiasis (control) (n=6 each). Furthermore, patients with PSC-associated cholangiocarcinoma (CC) and with CC without concomitant PSC were analyzed. None of the patients showed signs of inflammation or infection based on clinical and laboratory examinations. Proteins overexpressed in patients with PSC relative to control patients were detected by two-dimensional difference gel electrophoresis and identified by liquid chromatography-tandem mass spectrometry. Functional proteomic analysis was performed using STRING software. A total of 101 proteins were overexpressed in the bile fluid of patients with PSC but not in those of controls; the majority of these were predicted to be intracellular and related to the ribosomal and proteasomal pathways. On the other hand, 91 proteins were found only in the bile fluid of controls; most were derived from the extracellular space and were linked to cell adhesion, the complement system, and the coagulation cascade. In addition, proteins associated with inflammation and the innate immune response-e.g., cluster of differentiation 14, annexin-2, and components of the complement system-were upregulated in PSC. The most prominent pathways in PSC/CC-patients were inflammation associated cytokine and chemokine pathways, whereas in CC-patients the Wnt signaling pathway was upregulated. In PSC/CC-patients DIGE-analysis revealed biliary CD14 and Annexin-4 expression, among others, as the most prominent protein that discriminates between both cohorts. Thus, the bile-duct bile proteome of patients with PSC shows disease-specific changes associated with inflammation and the innate immune response even in the absence of obvious clinical signs of cholangitis, malignancy, or inflammation. This article is part of a Special Issue entitled: Cholangiocytes in Health and Diseaseedited by Jesus Banales, Marco Marzioni and Peter Jansen.

Fut2 genotype is a risk factor for dominant stenosis and biliary candida infections in primary sclerosing cholangitis.

BACKGROUND: A recent genome-wide association study identified the FUT2 secretor status and genotype defined by the single-nucleotide polymorphism rs601338 as potential genetic risk factor in primary sclerosing cholangitis (PSC), which significantly influences biliary bacterial composition. AIM: To determine the impact of the rs601338-FUT2 genotype on frequency of biliary infections, development of dominant stenosis and liver-transplantation-free survival in patients with PSC. METHODS: Cohort study of 215 patients with PSC treated at our tertiary care centre with respect to their rs601338-FUT2 genotype. Results of endoscopic retrograde cholangiography and bile culture were analysed; 639 biliary samples were obtained, cultured and subjected to microbial analysis. Clinical and laboratory data were analysed using chart reviews. RESULTS: For the rs601338-FUT2 genotype, 69 patients (32.1%) were found to be wildtype (GG), 97 (45.1%) patients were heterozygous (AG) and 49 patients (22.8%) were homozygous-mutated (AA). In addition to alterations in the bacterial pattern, especially in heterozygous carriers, patients with mutated alleles had a marked increase in the frequency of biliary Candida infections (P = 0.025). Further, patients with mutated alleles showed an increased frequency of episodes of cholangitis (P = 0.0025), development of dominant stenosis (P < 0.002) and a reduced actuarial transplantation-free survival (P = 0.044). Levels of biliary Ca19-9 were significantly elevated in the homozygous-mutated patients. CONCLUSIONS: The rs601338-FUT2 genotype is strongly associated with episodes of cholangitis, fungobilia and the incidence of dominant stenosis, which are three clinical hallmarks of PSC; FUT2 is thus an important genetic risk factor for host-microbial diversity and disease progression in PSC.

Helix bundles and coiled coils in alpha-spectrin and tropomyosin: a theoretical CD study.

The dipole interaction model is used to investigate the effects of interactions between helices and supertwisting of helices by determining whether the predicted UV absorption and CD spectra for the three-helix bundle and coiled coil are significantly different from spectra for the single straight alpha-helix. Crystallographic data by Yan et al. for alpha-spectrin are used to construct a three-helix bundle of poly(L-alanine) modeling the protein. Backbone torsion angles represented by Fourier series are used to generate supertwisted helices and coiled coil models of poly(L-alanine) that have pitch, radius, and residue repeat similar to experimental crystallographic data on tropomyosin. Calculated CD spectra are compared with available experimental data. Theoretical spectra for the three-helix bundle and the supertwisted structures are quite similar to predictions for the straight alpha-helix of the same length with similar torsion angles, suggesting that CD is primarily dependent on the average backbone conformation and would not be a sensitive tool for distinguishing between single straight helices and closely packed or twisted alpha-helices.