Georg Oberhuber

The FXR agonist PX20606 ameliorates portal hypertension by targeting vascular remodelling and sinusoidal dysfunction

BACKGROUND & AIMS Steroidal farnesoid X receptor (FXR) agonists demonstrated potent anti-fibrotic activities and lowered portal hypertension in experimental models. The impact of the novel non-steroidal and selective FXR agonist PX20606 on portal hypertension and fibrosis was explored in this study. METHODS In experimental models of non-cirrhotic (partial portal vein ligation, PPVL, 7days) and cirrhotic (carbon tetrachloride, CCl4, 14weeks) portal hypertension, PX20606 (PX,10mg/kg) or the steroidal FXR agonist obeticholic acid (OCA,10mg/kg) were gavaged. We then measured portal pressure, intrahepatic vascular resistance, liver fibrosis and bacterial translocation. RESULTS PX decreased portal pressure in non-cirrhotic PPVL (12.6±1.7 vs. 10.4±1.1mmHg; p=0.020) and cirrhotic CCl4 (15.2±0.5 vs. 11.8±0.4mmHg; p=0.001) rats. In PPVL animals, we observed less bacterial translocation (-36%; p=0.041), a decrease in lipopolysaccharide binding protein (-30%; p=0.024) and splanchnic tumour necrosis factor α levels (-39%; p=0.044) after PX treatment. In CCl4 rats, PX decreased fibrotic Sirius Red area (-43%; p=0.005), hepatic hydroxyproline (-66%; p<0.001), and expression of profibrogenic proteins (Col1a1, α smooth muscle actin, transforming growth factor β). CCl4-PX rats had significantly lower transaminase levels and reduced hepatic macrophage infiltration. Moreover, PX induced sinusoidal vasodilation (upregulation of cystathionase, dimethylaminohydrolase (DDAH)1, endothelial nitric oxide synthase (eNOS), GTP-cyclohydrolase1) and reduced intrahepatic vasoconstriction (downregulation of endothelin-1, p-Moesin). In cirrhosis, PX improved endothelial dysfunction (decreased von-Willebrand factor) and normalized overexpression of vascular endothelial growth factor, platelet-derived growth factor and angiopoietins. While short-term 3-day PX treatment reduced portal pressure (-14%; p=0.041) by restoring endothelial function, 14week PX therapy additionally inhibited sinusoidal remodelling and decreased portal pressure to a greater extent (-22%; p=0.001). In human liver sinusoidal endothelial cells, PX increased eNOS and DDAH expression. CONCLUSIONS The non-steroidal FXR agonist PX20606 ameliorates portal hypertension by reducing liver fibrosis, vascular remodelling and sinusoidal dysfunction. LAY SUMMARY The novel drug PX20606 activates the bile acid receptor FXR and shows beneficial effects in experimental liver cirrhosis: In the liver, it reduces scarring and inflammation, and also widens blood vessels. Thus, PX20606 leads to an improved blood flow through the liver and decreases hypertension of the portal vein. Additionally, PX20606 improves the altered intestinal barrier and decreases bacterial migration from the gut.

ADAM17 is required for EGF-R-induced intestinal tumors via IL-6 trans-signaling.

Colorectal cancer is treated with antibodies blocking epidermal growth factor receptor (EGF-R), but therapeutic success is limited. EGF-R is stimulated by soluble ligands, which are derived from transmembrane precursors by ADAM17-mediated proteolytic cleavage. In mouse intestinal cancer models in the absence of ADAM17, tumorigenesis was almost completely inhibited, and the few remaining tumors were of low-grade dysplasia. RNA sequencing analysis demonstrated down-regulation of STAT3 and Wnt pathway components. Because EGF-R on myeloid cells, but not on intestinal epithelial cells, is required for intestinal cancer and because IL-6 is induced via EGF-R stimulation, we analyzed the role of IL-6 signaling. Tumor formation was equally impaired in IL-6−/− mice and sgp130Fc transgenic mice, in which only trans-signaling via soluble IL-6R is abrogated. ADAM17 is needed for EGF-R–mediated induction of IL-6 synthesis, which via IL-6 trans-signaling induces &bgr;-catenin–dependent tumorigenesis. Our data reveal the possibility of a novel strategy for treatment of colorectal cancer that could circumvent intrinsic and acquired resistance to EGF-R blockade.

Deviations of the immune cell landscape between healthy liver and hepatocellular carcinoma

Tumor-infiltrating immune cells are highly relevant for prognosis and identification of immunotherapy targets in hepatocellular carcinoma (HCC). The recently developed CIBERSORT method allows immune cell profiling by deconvolution of gene expression microarray data. By applying CIBERSORT, we assessed the relative proportions of immune cells in 41 healthy human livers, 305 HCC samples and 82 HCC adjacent tissues. The obtained immune cell profiles provided enumeration and activation status of 22 immune cell subtypes. Mast cells were evaluated by immunohistochemistry in ten HCC patients. Activated mast cells, monocytes and plasma cells were decreased in HCC, while resting mast cells, total and naïve B cells, CD4+ memory resting and CD8+ T cells were increased when compared to healthy livers. Previously described S1, S2 and S3 molecular HCC subclasses demonstrated increased M1-polarized macrophages in the S3 subclass with good prognosis. Strong total immune cell infiltration into HCC correlated with total B cells, memory B cells, T follicular helper cells and M1 macrophages, whereas weak infiltration was linked to resting NK cells, neutrophils and resting mast cells. Immunohistochemical analysis of patient samples confirmed the reduced frequency of mast cells in human HCC tumor tissue as compared to tumor adjacent tissue. Our data demonstrate that deconvolution of gene expression data by CIBERSORT provides valuable information about immune cell composition of HCC patients.

Gastric adenocarcinoma and proximal polyposis of the stomach (GAPPS) – a rare recently described gastric polyposis syndrome – report of a case

In rare cases with multiple gastric polyps in the corpus and fundus, a recently described gastric polyposis syndrome called gastric adenocarcinoma and proximal polyposis of the stomach (GAPPS) has to be considered. We report on the findings in a patient fulfilling the criteria of this disease.A female patient born in 1977 underwent gastroscopy in 2005 due to recurrent abdominal pain. Endoscopy revealed more than 100 fundic gland polyps in the corpus and fundus. An ileocolonoscopy was inconspicuous. The patient did not take proton pump inhibitors. In follow-up biopsies, fundic gland polyps with low-grade dysplasia were observed. In 2015 gastroscopy with biopsy revealed for the first time high-grade dysplasia in a polyp, and the patient underwent prophylactic gastrectomy.Macroscopic examination of the gastrectomy specimen revealed hundreds of polyps predominantly measuring 3 mm in diameter covering the fundus and corpus. Histology showed fundic gland polyps, mainly covered by normal appearing foveolae. However, several of them were covered by lesions reminiscent of gastric foveolar adenomas with low- and focally high-grade dysplasia. Molecular pathology revealed a point mutation in the adenomatous polyposis coli promotor 1B. These findings in conjunction with the knowledge that the patients father had died of gastric carcinoma in his 50 s led to the diagnosis of the autosomal dominant syndrome GAPPS, which has hitherto been described in 9 families.

Iron deficiency workup reveals high incidence of autoimmune gastritis with parietal cell antibody as reliable screening test

Iron deficiency (ID) workup is a common challenge for gastrointestinal endoscopy. In premenopausal women current guidelines recommend serologic evaluation of coeliac disease only. Here we systematically tested serologic screening for autoimmune gastritis (AIG) in a large cohort of patients with ID. This is a retrospective analysis of patients who attended an out-patient clinic specialized for ID. Patients with ferritin <50 µg/L or transferrin saturation <15% were included. Laboratory workup included endomysial antibodies and parietal-cell antibodies (PCA). Upper gastrointestinal endoscopy with pH-measurement of gastric juice and histology was performed to confirm positive serologic results. Three hundred seventy-three patients with ID were included, about half of whom were anemic. Patients were predominately female with a median age of 40 (confidence interval 11). Positive endomysial antibodies were found in 4 (1%) patients, elevated levels of PCA (>20 U/mL) were found in 69 (18.5%) patients, PCA >100 U/mL in 23 (6.2%). Twenty-six were followed up by gastroscopy; in 12 of 26 patients the diagnosis of AIG was confirmed by histology with 2 additional patients diagnosed as early and/or questionable AIG. A sensitivity of 93% and a specificity of 98% were estimated for a PCA cut-off of 100 U/mL. In 20 patients gastric pH was measured. Achlorhydria was found in 7 patients all diagnosed with AIG. In this ID cohort AIG is by far more common than coeliac disease. PCA above 100 U/mL are a sensitive and specific cut-off for workup of patients with ID prior to endoscopy. Serologic suspicion of AIG helps preselection of patients for endoscopic workup for ID.

The soluble guanylate cyclase stimulator riociguat reduces fibrogenesis and portal pressure in cirrhotic rats

In cirrhotic patients, portal hypertension (PHT) deteriorates survival, yet treatment options are limited. A major contributor to increased intrahepatic vasoconstriction in PHT is dysfunctional nitric-oxide signaling. Soluble guanylate cyclase (sGC) is the receptor of nitric-oxide and can be stimulated by riociguat. Riociguat is approved for pulmonary hypertension but has not been studied in liver cirrhosis. In this study we assessed the effects of riociguat on PHT and liver fibrosis in cholestatic (bile duct ligation, BDL) and toxic (carbon-tetrachloride, CCl4) rat models. In cirrhotic livers sGC expression was upregulated. In BDL rats, riociguat reduced liver fibrosis and decreased portal pressure without affecting systemic hemodynamics. In an early BDL disease stage, riociguat decreased bile duct proliferation, improved sinusoidal vascular dysfunction and inhibited angiogenesis. In advanced BDL riociguat exhibited anti-inflammatory effects. In CCl4 rats the beneficial effects of riociguat treatment were less pronounced and confined to an early disease stage. Similarly, in patients with cholestatic cirrhosis and PHT nitrates (that induce sGC activity) decreased portal pressure more effectively than in patients with non-cholestatic etiology. We also found an improvement of transaminases in patients with pulmonary hypertension receiving riociguat. Our findings support the clinical development of sGC stimulators in patients with cirrhotic PHT.