A defect in endothelial autophagy occurs in patients with non-alcoholic steatohepatitis and promotes inflammation and fibrosis.

BACKGROUND & AIMS: Previous studies demonstrated that autophagy is protective in hepatocytes and macrophages, but detrimental in hepatic stellate cells in chronic liver diseases. The role of autophagy in liver sinusoidal endothelial cells (LSECs) in non-alcoholic steatohepatitis (NASH) is unknown. Our aim was to analyze the potential implication of autophagy in LSECs in NASH and liver fibrosis. METHODS: We analyzed autophagy in LSECs from patients using transmission electron microscopy. We determined the consequences of a deficiency in autophagy: (a) on LSEC phenotype, using primary LSECs and an LSEC line; (b) on early stages of NASH and on advanced stages of liver fibrosis, using transgenic mice deficient in autophagy specifically in endothelial cells and fed a high-fat diet or chronically treated with carbon tetrachloride, respectively. RESULTS: Patients with NASH had half as many LSECs containing autophagic vacuoles as patients without liver histological abnormalities, or with simple steatosis. LSECs from mice deficient in endothelial autophagy displayed an upregulation of genes implicated in inflammatory pathways. In the LSEC line, deficiency in autophagy enhanced inflammation (Ccl2, Ccl5, Il6 and VCAM-1 expression), features of endothelial-to-mesenchymal transition (α-Sma, Tgfb1, Col1a2 expression) and apoptosis (cleaved caspase-3). In mice fed a high-fat diet, deficiency in endothelial autophagy induced liver expression of inflammatory markers (Ccl2, Ccl5, Cd68, Vcam-1), liver cell apoptosis (cleaved caspase-3) and perisinusoidal fibrosis. Mice deficient in endothelial autophagy treated with carbon tetrachloride also developed more perisinusoidal fibrosis. CONCLUSIONS: A defect in autophagy in LSECs occurs in patients with NASH. Deficiency in endothelial autophagy promotes the development of liver inflammation, features of endothelial-to-mesenchymal transition, apoptosis and liver fibrosis in the early stages of NASH, but also favors more advanced stages of liver fibrosis. LAY SUMMARY: Autophagy is a physiological process controlling endothelial homeostasis in vascular beds outside the liver. This study demonstrates that autophagy is defective in the liver endothelial cells of patients with non-alcoholic steatohepatitis. This defect promotes liver inflammation and fibrosis at early stages of non-alcoholic steatohepatitis, but also at advanced stages of chronic liver disease.

Liver microRNA-21 is overexpressed in non-alcoholic steatohepatitis and contributes to the disease in experimental models by inhibiting PPARα expression.

OBJECTIVE: Previous studies suggested that microRNA-21 may be upregulated in the liver in non-alcoholic steatohepatitis (NASH), but its role in the development of this disease remains unknown. This study aimed to determine the role of microRNA-21 in NASH. DESIGN: We inhibited or suppressed microRNA-21 in different mouse models of NASH: (a) low-density lipoprotein receptor-deficient (Ldlr-/-) mice fed a high-fat diet and treated with antagomir-21 or antagomir control; (b) microRNA-21-deficient and wild-type mice fed a methionine-choline-deficient (MCD) diet; (c) peroxisome proliferation-activator receptor α (PPARα)-deficient mice fed an MCD diet and treated with antagomir-21 or antagomir control. We assessed features of NASH and determined liver microRNA-21 levels and cell localisation. MicroRNA-21 levels were also quantified in the liver of patients with NASH, bland steatosis or normal liver and localisation was determined. RESULTS: Inhibiting or suppressing liver microRNA-21 expression reduced liver cell injury, inflammation and fibrogenesis without affecting liver lipid accumulation in Ldlr-/- fed a high-fat diet and in wild-type mice fed an MCD diet. Liver microRNA-21 was overexpressed, primarily in biliary and inflammatory cells, in mouse models as well as in patients with NASH, but not in patients with bland steatosis. PPARα, a known microRNA-21 target, implicated in NASH, was decreased in the liver of mice with NASH and restored following microRNA-21 inhibition or suppression. The effect of antagomir-21 was lost in PPARα-deficient mice. CONCLUSIONS: MicroRNA-21 inhibition or suppression decreases liver injury, inflammation and fibrosis, by restoring PPARα expression. Antagomir-21 might be a future therapeutic strategy for NASH.

A new NRF2 activator for the treatment of human metabolic dysfunction-associated fatty liver disease.

Background & Aims: Oxidative stress triggers metabolic-associated fatty liver disease (MAFLD) and fibrosis. Previous animal studies demonstrated that the transcription factor nuclear factor (erythroid-derived 2)-like 2 (NRF2), the master regulator of antioxidant response, protects against MAFLD and fibrosis. S217879, a next generation NRF2 activator has been recently shown to trigger diet-induced steatohepatitis resolution and to reduce established fibrosis in rodents. Our aim was to evaluate the therapeutic potential of S217879 in human MAFLD and its underlying mechanisms using the relevant experimental 3D model of patient-derived precision cut liver slices (PCLS). Methods: We treated PCLS from 12 patients with varying stages of MAFLD with S217879 or elafibranor (peroxisome proliferator-activated receptor [PPAR]α/δ agonist used as a referent molecule) for 2 days. Safety and efficacy profiles, steatosis, liver injury, inflammation, and fibrosis were assessed as well as mechanisms involved in MAFLD pathophysiology, namely antioxidant response, autophagy, and endoplasmic reticulum-stress. Results: Neither elafibranor nor S217879 had toxic effects at the tested concentrations on human PCLS with MAFLD. PPARα/δ and NRF2 target genes (pyruvate dehydrogenase kinase 4 [PDK4], fibroblast growth factor 21 [FGF21], and NAD(P)H quinone dehydrogenase 1 [NQO1], heme oxygenase 1 [HMOX1], respectively) were strongly upregulated in PCLS in response to elafibranor and S217879, respectively. Compared with untreated PCLS, elafibranor and S217879-treated slices displayed lower triglycerides and reduced inflammation (IL-1ß, IL-6, chemokine (C-C motif) ligand 2 [CCL2]). Additional inflammatory markers (chemokine (C-C motif) ligand 5 [CCL5], stimulator of interferon genes [STING], intercellular adhesion molecule-1 [ICAM-1], vascular cell adhesion molecule-1 [VCAM-1]) were downregulated by S217879. S217879 but not elafibranor lowered DNA damage (phospho-Histone H2A.X [p-H2A.X], RAD51, X-ray repair cross complementing 1 [XRCC1]) and apoptosis (cleaved caspase-3), and inhibited fibrogenesis markers expression (alpha smooth muscle actin [α-SMA], collagen 1 alpha 1 [COL1A1], collagen 1 alpha 2 [COL1A2]). Such effects were mediated through an improvement of lipid metabolism, activated antioxidant response and enhanced autophagy, without effect on endoplasmic reticulum-stress. Conclusions: This study highlights the therapeutic potential of a new NRF2 activator for MAFLD using patient-derived PCLS supporting the evaluation of NRF2 activating strategies in clinical trials. Impact and implications: Oxidative stress is a major driver of metabolic-associated fatty liver disease (MAFLD) development and progression. Nuclear factor (erythroid-derived 2)-like 2, the master regulator of the antioxidative stress response, is an attractive therapeutic target for the treatment of MAFLD. This study demonstrates that S217879, a new potent and selective nuclear factor (erythroid-derived 2)-like 2 activator, displays antisteatotic effects, lowers DNA damage, apoptosis, and inflammation and inhibits fibrogenesis in human PCLS in patients with MAFLD.

Computational Learning of microRNA-Based Prediction of Pouchitis Outcome After Restorative Proctocolectomy in Patients With Ulcerative Colitis.

BACKGROUND: Ileal pouch-anal anastomosis (IPAA) is the standard of care after total proctocolectomy for ulcerative colitis (UC). However, inflammation often develops in the pouch, leading to acute or recurrent/chronic pouchitis (R/CP). MicroRNAs (miRNA) are used as accurate diagnostic and predictive biomarkers in many human diseases, including inflammatory bowel diseases. Therefore, we aimed to identify an miRNA-based biomarker to predict the occurrence of R/CP in patients with UC after colectomy and IPAA. METHODS: We conducted a retrospective study in 3 tertiary centers in France. We included patients with UC who had undergone IPAA with or without subsequent R/CP. Paraffin-embedded biopsies collected from the terminal ileum during the proctocolectomy procedure were used for microarray analysis of miRNA expression profiles. Deep neural network-based classifiers were used to identify biomarkers predicting R/CP using miRNA expression and relevant biological and clinical factors in a discovery cohort of 29 patients. The classification algorithm was tested in an independent validation cohort of 28 patients. RESULTS: A combination of 11 miRNA expression profiles and 3 biological/clinical factors predicted the outcome of R/CP with 88% accuracy (area under the curve = 0.94) in the discovery cohort. The performance of the classification algorithm was confirmed in the validation cohort with 88% accuracy (area under the curve = 0.90). Apoptosis, cytoskeletal regulation by Rho GTPase, and fibroblast growth factor signaling were the most dysregulated targets of the 11 selected miRNAs. CONCLUSIONS: We developed and validated a computational miRNA-based algorithm for accurately predicting R/CP in patients with UC after IPAA.

Heterogeneity of tumor prognostic markers: a reproducibility study applied to liver metastases of pancreatic endocrine tumors.

Liver biopsy of metastatic pancreatic endocrine tumors allows confirmation of the diagnosis and assessment of prognosis. However, sampling variability is a potential limitation. Our aim was to use the tissue microarray technique to assess the heterogeneity of three prognostic markers, ie, MIB-1 proliferation index, microvascular density and somatostatin receptor type 2, inside single or between synchronous or metachronous liver metastases of pancreatic endocrine tumors. Tissue microarrays were constructed, which included core biopsies taken from surgically resected liver metastases in 29 patients. MIB-1, microvascular density and somatostatin receptor type 2 were evaluated after immunostaining. The heterogeneity was highlighted by the calculation of the reproducibility of the values of two cores randomly selected among all the cores studied. For quantitative variables, it was assessed by the intraclass correlation coefficient and by a Bland-Altman approach. For qualitative variables, observed agreement and weighted kappa were given. A total of 184 liver metastases were analyzed. For MIB-1, the intraclass correlation coefficients were 0.63, 0.69 and 0.67 and for microvascular density, the intraclass correlation coefficients were 0.48, 0.60 and 0.00, respectively, in single, synchronous and metachronous liver metastases. The variability increased for higher mean values of microvascular density. For somatostatin receptor type 2, the observed agreements were 91% (kappa=0.81), 69% (kappa=0.49) and 79% (kappa=0.68) in single, synchronous and metachronous liver metastases, respectively. In conclusion, tissue microarray analysis identifies heterogeneity of protein expression in pancreatic endocrine metastases, which depends on the marker tested. The reproducibility is better for MIB-1 and somatostatin receptor type 2 than for microvascular density. Sampling variability should be taken into consideration as a potential limitation to the assessment of prognostic and therapeutic markers in biopsy samples from metastatic pancreatic endocrine tumors.

Frozen sectioning of the pancreatic cut surface during resection of intraductal papillary mucinous neoplasms of the pancreas is useful and reliable: a prospective evaluation.

OBJECTIVE: To prospectively evaluate the accuracy of frozen sectioning (FS) of the pancreatic transection margin and its influence on surgery during resection of intraductal papillary and mucinous neoplasms (IPMNs). SUMMARY BACKGROUND DATA: Preoperative assessment of IPMN extension is difficult and transection margin is frequently tumoral on the surgical specimen. PATIENTS AND METHODS: FS was performed in 127 patients who underwent partial pancreatectomy for IPMN from 1996 to 2004, corresponding to 90 pancreaticoduodenectomies (1-4 successive FS; total = 132), 25 distal pancreatectomies (1-2 FS; total = 27), and 12 medial pancreatectomies (2-4 FS; total = 29). Dysplasia was graded in both main (MD) and branch ducts (BD), and pancreatectomy was extended if FS revealed at least IPMN adenoma on the MD or borderline IPMN on BD (defined as "significant" lesions). RESULTS: The 188 FS revealed that MD and BD epithelium comprised significant noninvasive lesions in 49 and 13 cases, respectively, and infiltrating carcinoma in 4 other ones. Definitive examination corroborated FS in 176 of 188 cases (94%). Altogether, 54 of 188 (29%) FS comprised significant lesions that resulted in 46 additional resections in 38 patients (30%). Eight patients did not have additional resection because of either high operative risk or preoperative diagnosis of noncurable infiltrating carcinoma. The 134 FS without significant lesions were associated with 7 additional resections mainly because of macroscopic suspicion of another tumor location. Conflicting results between FS and definitive examination resulted in inadequate extent of pancreatectomy in 4 patients (3%). CONCLUSIONS: Results of FS of the transection margin are confirmed by definitive examination in 94% of cases. According to our protocol, FS changes the extent of resection in 30% of patients and allows adequate resection in 97% of patients.