ObjectivePancreatic autoantibodies (PABs), comprising antibodies against glycoprotein 2 (anti-GP2), are typically associated with complicated phenotypes in Crohn's disease, but have also been observed with variable frequencies in patients with UC. In a previous study, we observed a high frequency of primary sclerosing cholangitis (PSC) in patients with anti-GP2-positive UC. We therefore aimed to characterise the role of anti-GP2 in PSC.DesignIn an evaluation phase, sera from 138 well-characterised Norwegian patients with PSC were compared with healthy controls (n=52), and patients with UC without PSC (n=62) for the presence of PABs by indirect immunofluorescence. Further, 180 German patients with PSC served as a validation cohort together with 56 cases of cholangiocarcinoma without PSC, 20 of secondary sclerosing cholangitis (SSC) and 18 of autoimmune hepatitis.ResultsAnti-GP2 IgA specifically occurred at considerable rates in large bile duct diseases (cholangiocarcinoma=36%, PSC and SSC about 50%). In PSC, anti-GP2 IgA consistently identified patients with poor survival during follow-up (Norwegian/German cohort: p Log Rank=0.016/0.018). Anti-GP2 IgA was associated with the development of cholangiocarcinoma in both PSC cohorts, yielding an overall OR of cholangiocarcinoma in patients with anti-GP2 IgA-positive PSC of 5.0 (p=0.001). Importantly, this association remained independent of disease duration, bilirubin level and age.ConclusionsAnti-GP2 IgA can be hypothesised as a novel marker in large bile duct diseases. In particular, in PSC, anti-GP2 IgA identified a subgroup of patients with severe phenotype and poor survival due to cholangiocarcinoma. Anti-GP2 IgA may therefore be a clinically valuable tool for risk stratification in PSC.

ObjectiveNon-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease and is associated with an enhanced risk for liver and cardiovascular diseases and mortality. NAFLD can progress from simple hepatic steatosis to non-alcoholic steatohepatitis (NASH). However, the mechanisms predisposing to this progression remain undefined. Notably, hepatic mitochondrial dysfunction is a common finding in patients with NASH. Due to a lack of appropriate experimental animal models, it has not been evaluated whether this mitochondrial dysfunction plays a causative role for the development of NASH.MethodsTo determine the effect of a well-defined mitochondrial dysfunction on liver physiology at baseline and during dietary challenge, C57BL/6J-mtFVB/N mice were employed. This conplastic inbred strain has been previously reported to exhibit decreased mitochondrial respiration likely linked to a non-synonymous gene variation (nt7778 G/T) of the mitochondrial ATP synthase protein 8 (mt-ATP8).ResultsAt baseline conditions, C57BL/6J-mtFVB/N mice displayed hepatic mitochondrial dysfunction characterized by decreased ATP production and increased formation of reactive oxygen species (ROS). Moreover, genes affecting lipid metabolism were differentially expressed, hepatic triglyceride and cholesterol levels were changed in these animals, and various acyl-carnitines were altered, pointing towards an impaired mitochondrial carnitine shuttle. However, over a period of twelve months, no spontaneous hepatic steatosis or inflammation was observed. On the other hand, upon dietary challenge with either a methionine and choline deficient diet or a western-style diet, C57BL/6J-mtFVB/N mice developed aggravated steatohepatitis as characterized by lipid accumulation, ballooning of hepatocytes and infiltration of immune cells.ConclusionsWe observed distinct metabolic alterations in mice with a mitochondrial polymorphism associated hepatic mitochondrial dysfunction. However, a second hit, such as dietary stress, was required to cause hepatic steatosis and inflammation. This study suggests a causative role of hepatic mitochondrial dysfunction in the development of experimental NASH.

We found distinct clinical phenotypes to be associated with PAB positivity. Therefore, determination of PABs and their subgroup analysis might identify patients with complicated disease behavior. However, the clinical relevance of our findings should be further evaluated in prospective cohorts.

Adherent-invasive Escherichia coli have been suggested to play a pivotal role within the pathophysiology of inflammatory bowel disease (IBD). Autoantibodies against distinct splicing variants of glycoprotein 2 (GP2), an intestinal receptor of the bacterial adhesin FimH, frequently occur in IBD patients. Hence, we aimed to functionally characterize GP2-directed autoantibodies as a putative part of IBD’s pathophysiology. Ex vivo, GP2-splicing variant 4 (GP2#4) but not variant 2 was expressed on intestinal M or L cells with elevated expression patterns in IBD patients. The GP2#4 expression was induced in vitro by tumor necrosis factor (TNF)-α. The IBD-associated GP2 autoantibodies inhibited FimH binding to GP2#4 and were decreased in anti-TNFα-treated Crohn’s disease patients with ileocolonic disease manifestation. In vivo, mice immunized against GP2 before infection with adherent-invasive bacteria displayed exacerbated intestinal inflammation. In summary, autoimmunity against intestinal expressed GP2#4 results in enhanced attachment of flagellated bacteria to the intestinal epithelium and thereby may drive IBD’s pathophysiology.

Awareness of ischemic colitis as a complication in comparable settings is favorable. So far, early countermeasures against even modest hypotension in patients with comparable past history may be considered on an individual basis depending on the entirety of risk factors. However, prospective studies are necessary to evaluate potential risk profiles for ischemic colitis in terms of colonoscopy.

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ZusammenfassungBeschrieben wird eine Hantavirus-assoziierte, ausgeprägte Myositis als seltene Differenzialdiagnose zu einer Polymyositis. In der Literatur wird für die Pathogenese der Hantaviruserkrankung weniger eine direkte virale Zytopathologie als eine sekundäre Immundysregulation mit Induktion eines Kapillarlecks diskutiert. Wir beschreiben mit diesem Fall erstmalig die erfolgreiche Behandlung einer protrahiert verlaufenen Hantavirus-Myositis mittels Einsatzes von hoch dosierten Glukokortikoiden und Cyclophosphamid, gefolgt von Ciclosporin und Methotrexat (MTX).

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