miR-33 deletion in hepatocytes attenuates NAFLD-NASH-HCC progression.

The complexity of the mechanisms underlying non-alcoholic fatty liver disease (NAFLD) progression remains a significant challenge for the development of effective therapeutics. miRNAs have shown great promise as regulators of biological processes and as therapeutic targets for complex diseases. Here, we study the role of hepatic miR-33, an important regulator of lipid metabolism, during the progression of NAFLD and the development of hepatocellular carcinoma (HCC). We report that miR-33 is elevated in the livers of humans and mice with NAFLD and that its deletion in hepatocytes (miR-33 HKO) improves multiple aspects of the disease, including steatosis and inflammation, limiting the progression to non-alcoholic steatohepatitis (NASH), fibrosis and HCC. Mechanistically, hepatic miR-33 deletion reduces lipid synthesis and promotes mitochondrial fatty acid oxidation, reducing lipid burden. Additionally, absence of miR-33 alters the expression of several known miR-33 target genes involved in metabolism and results in improved mitochondrial function and reduced oxidative stress. The reduction in lipid accumulation and liver injury resulted in decreased YAP/TAZ pathway activation, which may be involved in the reduced HCC progression in HKO livers. Together, these results suggest suppressing hepatic miR-33 may be an effective therapeutic approach to temper the development of NAFLD, NASH, and HCC in obesity.

Hepatocyte-specific miR-33 deletion attenuates NAFLD-NASH-HCC progression.

The complexity of the multiple mechanisms underlying non-alcoholic fatty liver disease (NAFLD) progression remains a significant challenge for the development of effective therapeutics. miRNAs have shown great promise as regulators of biological processes and as therapeutic targets for complex diseases. Here, we study the role of hepatic miR-33, an important regulator of lipid metabolism, during the progression of NAFLD. We report that miR-33 is overexpressed in hepatocytes isolated from mice with NAFLD and demonstrate that its specific suppression in hepatocytes (miR-33 HKO ) improves multiple aspects of the disease, including insulin resistance, steatosis, and inflammation and limits the progression to non-alcoholic steatohepatitis (NASH), fibrosis and hepatocellular carcinoma (HCC). Mechanistically, we find that hepatic miR-33 deficiency reduces lipid biosynthesis and promotes mitochondrial fatty acid oxidation to reduce lipid burden in hepatocytes. Additionally, miR-33 deficiency improves mitochondrial function, reducing oxidative stress. In miR-33 deficient hepatocytes, we found an increase in AMPKα activation, which regulates several pathways resulting in the attenuation of liver disease. The reduction in lipid accumulation and liver injury resulted in decreased transcriptional activity of the YAP/TAZ pathway, which may be involved in the reduced progression to HCC in the HKO livers. Together, these results suggest suppressing hepatic miR-33 may be an effective therapeutic approach at different stages of NAFLD/NASH/HCC disease progression.

Serum lipopolysaccharide-binding protein in endotoxemic patients with inflammatory bowel disease.

BACKGROUND: In inflammatory bowel disease (IBD), enhanced inflammatory activity in the gut is thought to increase the risk of bacterial translocation and endotoxemia. By searching for signs of endotoxin-signaling cascade activation, including augmented levels of endotoxin, lipopolysaccharide-binding protein (LBP), and soluble CD14 receptor (sCD14), this prospective study sought to establish whether endotoxemia could contribute to greater clinical activity of disease. METHODS: Concentrations of plasma endotoxin, LBP, sCD14, several cytokines, acute phase proteins and clinical activity indices were determined in 104 patients with Crohn's disease (CD) and 52 patients with ulcerative colitis (UC). RESULTS: Endotoxemia was present in 48% of the patients with CD and in 28% of the patients with UC. The mean LBP was higher in patients with active CD (23.1 +/- 13.7 microg/mL) and UC (21.4 +/- 10.9 microg/mL) than in healthy controls (7.2 +/- 1.8 microg/mL; P < 0.01). Elevated serum concentrations of endotoxin and LBP were even detected in patients with inactive CD. Among the patients with active IBD, those with higher endotoxin levels had the worst clinical activity scores and the highest LBP levels. Treatment normalized LBP concentrations, from 29.1 +/- 13.0 to 15.2 +/- 7.3 microg/mL; (P < 0.05) in active CD and from 21.7 +/- 9.8 to 13.6 +/- 5.7 microg/mL; (P < 0.01) in active UC, along with normalizing endotoxin and sCD14 plasma concentrations. CONCLUSIONS: Patients with IBD show increased serum levels of endotoxin, LBP and sCD14. This alteration correlates with disease activity, with normal levels recovered after treatment, although less completely in Crohn's disease, and parallels a rise in proinflammatory cytokines, suggesting a contribution of bacterial products to the inflammatory cascade in these patients.

Análisis de la composición de ácido araquidónico y ácidos grasos omega-3 en plasma, membrana eritrocitaria y células inmunitarias de pacientes con cirrosis / Analysis of composition of arachidonic acid and fatty acids omega-3 in plasma, erythrocyte membrane and immune cells in patients with cirrhosis

Introducción y objetivo. La participación de mediadores lipídicos derivados del ácido araquidónico (AA) en la lesión hepatocelular de la cirrosis y su modulación por ácidos grasos omega-3 como los ácidos docosahexaenoico (DHA) y eicosapentaenoico (EPA) es un tema de interés creciente. El contenido de AA, EPA y DHA puede ser importante para explicar, entre otras funciones, el tono vasoconstrictor del hígado y la capacidad funcional (fagocitosis, producción de ROS) de las células inmunitarias observada en la cirrosis. El objetivo del trabajo fue estudiar las alteraciones en la composición de AA, DHA y EPA en plasma, membrana eritrocitaria y células inmunitarias de sangre periférica en pacientes con cirrosis y establecer su relación con el deterioro de la función hepática. Pacientes y métodos. Se analizó la composición de ácidos grasos de 42 pacientes con cirrosis clasificados según Child-Pugh y 10 controles sanos en plasma, membrana eritrocitaria y células mononucleares (PMBC) y polimorfonucleares (PMN) de sangre periférica por cromatografía de gases con detección por masas. Resultados y conclusiones. 1) Los cirróticos presentan un descenso significativo en los porcentajes de AA, EPA y DHA en plasma y un descenso significativo de AA en membrana eritrocitaria. 2) El contenido de AA en plasma y en membrana eritrocitaria correlaciona con el deterioro en la función hepática (según Child-Pugh) y no depende de un deficitario aporte nutricional. 3) La composición en AA y DHA está alterada en los PBMC de cirróticos, lo que pudiera tener importancia en la funcionalidad de las células inmunitarias de estos enfermos (AU)

Introduction and objetive. The involvement of lipid mediators derived from arachidonic acid (AA) in cirrhosis hepatocellular injury and its modulation by omega-3 fatty acids, such as docosahexaenoic acid (DHA) and eicosapentaenoic (EPA) is a topic of growing interest. The content of AA, EPA and DHA may be important to explain, among other things, the vasoconstrictor tone of liver and functional capacity (phagocytosis, ROS production) of immune cells observed in cirrhosis. The objective was to study alterations in the composition of AA, DHA and EPA in plasma, erythrocyte membranes and peripheral blood immune cells in patients with cirrhosis and determine their relationship with liver function impairment. Patients and methods. We analyzed the fatty acid composition of 42 patients with cirrhosis using the Child-Pugh classification, and 10 healthy controls in plasma, erythrocyte membrane and mononuclear cells (PBMCs) and polymorphonuclear (PMN) from peripheral blood using gas chromatography with mass detection. Results and conclusions. 1) Patients with cirrhosis showed significant decreases in the percentages of AA in plasma and erythrocyte membrane, as well as EPA and DHA in plasma. 2) AA content in plasma and erythrocyte membrane correlates with impaired liver function (Child scale) and it does not depend on a nutritional deficit. 3) AA and DHA composition varies also in PBMC (lymphocytes and monocytes) of cirrhosis, which may affect immune function of these cells (AU)