Fatty acid and endotoxin activate inflammasomes in mouse hepatocytes that release danger signals to stimulate immune cells

The pathogenesis of nonalcoholic steatohepatitis (NASH) and inflammasome activation involves sequential hits. The inflammasome, which cleaves pro-interleukin-1β (pro-IL-1β) into secreted IL-1β, is induced by endogenous and exogenous danger signals. Lipopolysaccharide (LPS), a toll-like receptor 4 ligand, plays a role in NASH and also activates the inflammasome. In this study, we hypothesized that the inflammasome is activated in NASH by multiple hits involving endogenous and exogenous danger signals. Using mouse models of methionine choline-deficient (MCD) diet-induced NASH and high-fat diet-induced NASH, we found up-regulation of the inflammasome [including NACHT, LRR, and PYD domains-containing protein 3 (NALP3; cryopyrin), apoptosis-associated speck-like CARD-domain containing protein, pannexin-1, and pro-caspase-1] at the messenger RNA (mRNA) level increased caspase-1 activity, and mature IL-1β protein levels in mice with steatohepatitis in comparison with control livers. There was no inflammasome activation in mice with only steatosis. The MCD diet sensitized mice to LPS-induced increases in NALP3, pannexin-1, IL-1β mRNA, and mature IL-1β protein levels in the liver. We demonstrate for the first time that inflammasome activation occurs in isolated hepatocytes in steatohepatitis. Our novel data show that the saturated fatty acid (FA) palmitic acid (PA) activates the inflammasome and induces sensitization to LPS-induced IL-1β release in hepatocytes. Furthermore, PA triggers the release of danger signals from hepatocytes in a caspase-dependent manner. These hepatocyte-derived danger signals, in turn, activate inflammasome, IL-1β, and tumor necrosis factor α release in liver mononuclear cells. CONCLUSION: Our novel findings indicate that saturated FAs represent an endogenous danger in the form of a first hit, up-regulate the inflammasome in NASH, and induce sensitization to a second hit with LPS for IL-β release in hepatocytes. Furthermore, hepatocytes exposed to saturated FAs release danger signals that trigger inflammasome activation in immune cells. Thus, hepatocytes play a key role in orchestrating tissue responses to danger signals in NASH.     

Alcohol Exposure as a Risk Factor for Adverse Outcomes in Elective Surgery

Background and Aims  

Alcohol consumption is a well-documented determinant of adverse perioperative outcome. We sought to determine the effect of active alcohol consumption following elective surgery.     

Tight metabolic control plus ACE inhibitor therapy improves GSD I nephropathy

The onset of microalbuminuria (MA) heralds the onset of glomerulopathy in patients with glycogen storage disease (GSD) type I. Unlike tubulopathy, which responds to improved metabolic control, glomerulopathy in GSD I is considered refractory to medical intervention, and it is thought to inexorably progress to overt proteinuria and renal failure. Recent reports of reduced microalbuminuria following strict adherence to therapy counter this view. In contrast to type Ia, little is known regarding the prevalence of kidney disease in GSD Ib, 0, III, VI, and IX. Subjects were evaluated with 24-h urine collections between 2005 and 2014 as part of a longitudinal study of the natural history of GSD. ACE inhibitor therapy (AIT) was commenced after documentation of microalbuminuria. Elevated urine albumin excretion was detected in 23 of 195 GSD Ia patients (11.7%) and six of 45 GSD Ib (13.3%). The median age of onset of microalbuminuria in GSD Ia was 24 years (range 9–56); in GSD Ib it was 25 years (range 20–38). Of 14 with GSD Ia who complied with dietary and AIT during the study period, microalbuminuria decreased in 11, in whom metabolic control improved. All 135 patients with the ketotic forms of GSD (0, III, VI and IX) consistently had normal microalbumin excretion. Strict adherence to dietary therapy and maintenance of optimal metabolic control is necessary to halt the progression of GSD Ia glomerulopathy in patients treated with AIT. With optimal care, protein excretion can be reduced and even normalize.     

Adult mouse model of early hepatocellular carcinoma promoted by alcoholic liver disease

AIM: To establish a mouse model of alcohol-driven hepatocellular carcinoma(HCC) that develops in livers with alcoholic liver disease(ALD).METHODS: Adult C57BL/6 male mice received multiple doses of chemical carcinogen diethyl nitrosamine(DEN) followed by 7 wk of 4% Lieber-De Carli diet. Serum alanine aminotransferase(ALT), alpha fetoprotein(AFP) and liver Cyp2e1 were assessed. Expression of F4/80, CD68 for macrophages and Ly6 G, MPO, E-selectin for neutrophils was measured. Macrophage polarization was determined by IL-1β/i NOS(M1) and Arg-1/IL-10/CD163/CD206(M2) expression. Liver steatosis and fibrosis were measured by oil-red-O and Sirius red staining respectively. HCC development was monitored by magnetic resonance imaging, confirmed by histology. Cellular proliferation was assessed by proliferating cell nuclear antigen(PCNA).RESULTS: Alcohol-DEN mice showed higher ALTs than pair fed- DEN mice throughout the alcohol feeding without weight gain. Alcohol feeding resulted in increased ALT, liver steatosis and inflammation compared to pair-fed controls. Alcohol-DEN mice had reduced steatosis and increased fibrosis indicatingadvanced liver disease. Molecular characterization showed high estlevels of both neutrophil and macrophage markers in alcohol-DEN livers. Importantly, M 2 macrophages were edominantly higher in alcohol-DEN livers. Magnetic resonance imaging revealed increased numbers of intrahepatic cysts and liver histology confirmed the presence of early HCC in alcohol-DEN mice compared to al l other groups. This correlated with increased serum alphafetoprotein, a marker of HCC, in alcohol-DEN mice. PCNA immunostaining revealed significantly increased hepatocyte proliferation in livers from alcohol-DEN compared to pair fed-DEN or alcohol-fed mice.CONCLUSION: We describe a new 12-wk HCC model in adult mice that develops in livers with alcoholic hepatitis and defines ALD as co-factor in HCC.     

Long-term changes in the antinociceptive potency of morphine or dexmedetomidine after a single treatment

Acute tolerance develops after a single administration of opiate or alpha(2)-adrenergic agonists, but the characteristics of the delayed type of acute tolerance have not been analyzed in acute and inflammatory thermal pain tests. We investigated the long-term changes in the antinociceptive potency of morphine (10 mg/kg) injected intraperitoneally and the alpha(2)-adrenoceptor agonist dexmedetomidine (150 microg/kg intraperitoneally) on acute heat pain (tail-flick test) sensitivity and on carrageenan-induced inflammatory thermal hyperalgesia (paw withdrawal test) after a second injection 7 days later. The first treatment did not influence the baseline values on Day 8 in either test. In the tail-flick test, the antinociceptive potency of morphine, but not that of dexmedetomidine, was significantly decreased after repeated administration, suggesting a delayed type of acute tolerance to morphine. In contrast, the antihyperalgesic effect of morphine in the paw withdrawal test did not change after repeated injection, whereas the potency of dexmedetomidine was increased on Day 8. There were significant differences between the inflamed and noninflamed sides on Day 1 but not on Day 8, revealing an increased potency of the drugs on the inflamed side. There was no sign of cross-tolerance between the two drugs in either pain test. These data indicate long-term changes in the antinociceptive potency of morphine or dexmedetomidine after single treatment in different heat pain tests.     

High-dose remifentanil does not impair cerebrovascular carbon dioxide reactivity in healthy male volunteers

BACKGROUND: Cerebrovascular carbon dioxide reactivity during high-dose remifentanil infusion was investigated in volunteers by measurement of regional cerebral blood flow (rCBF) and mean CBF velocity (CBFv). METHODS: Ten healthy male volunteers with a laryngeal mask for artificial ventilation received remifentanil at an infusion rate of 2 and 4 microg x kg-1 x min-1 under normocapnia, hypocapnia, and hypercapnia. Stable xenon-enhanced computed tomography and transcranial Doppler ultrasonography of the left middle cerebral artery were used to assess rCBF and mean CBFv, respectively. If required, blood pressure was maintained within baseline values with intravenous phenylephrine to avoid confounding effects of altered hemodynamics. RESULTS: Hemodynamic parameters were maintained constant over time. Remifentanil infusion at 2 and 4 microg x kg-1 x min-1 significantly decreased rCBF and mean CBFv. Both rCBF and mean CBFv increased as the arterial carbon dioxide tension increased from hypocapnia to hypercapnia, indicating that cerebrovascular reactivity remained intact. The average slopes of rCBF reactivity were 0.56 +/- 0.27 and 0.49 +/- 0.28 ml. 100 g-1 x min-1 x mmHg-1 for 2 and 4 microg x kg-1 x min-1 remifentanil, respectively (relative change in percent/mmHg: 1.9 +/- 0.8 and 1.6 +/- 0.5, respectively). The average slopes for mean CBFv reactivity were 1.61 +/- 0.95 and 1.54 +/- 0.83 cm x s-1 x mmHg-1 for 2 and 4 microg x kg-1 x min-1 remifentanil, respectively (relative change in percent/mmHg: 1.86 +/- 0.59 and 1.79 +/- 0.59, respectively). Preanesthesia and postanesthesia values of rCBF and mean CBFv did not differ. CONCLUSION: High-dose remifentanil decreases rCBF and mean CBFv without impairing cerebrovascular carbon dioxide reactivity. This, together with its known short duration of action, makes remifentanil a useful agent in the intensive care unit when sedation that can be titrated rapidly is required.