Wa Buurman

Lack of evidence for the role of human adenovirus-36 in obesity in a European cohort.

Adenovirus infection has been shown to increase adiposity in chickens, mice, and nonhuman primates. Adenovirus type 36 (Ad‐36) DNA was detected in adipose tissues in these animal trials. In the United States, Ad‐36 significantly correlates with obesity as illustrated by an Ad‐36 seroprevalence of 30% in obese individuals and 11% in nonobese individuals. We investigated the possibility of a similar correlation of Ad‐36 in Dutch and Belgian persons. In total, 509 serum samples were analyzed for Ad‐36 antibodies using a serum neutralization assay. In addition, PCR was used to detect adenoviral DNA in visceral adipose tissue of 31 severely obese surgical patients. Our results indicated an overall Ad‐36 seroprevalence of 5.5% increasing with age. BMI of Ad‐36 seropositive humans was not significantly different from seronegative humans. No adenoviral DNA could be found using PCR on visceral adipose tissue. In conclusion, this first Ad‐36 study in the Netherlands and in Belgium indicates that Ad‐36 does not play a role as a direct cause of BMI increase and obesity in humans in Western Europe.

Novel Evidence for Chronic Exposure to Endotoxin in Human Nonalcoholic Steatohepatitis

Background Endotoxin is hypothesized to play an important role in the activation of inflammatory pathways associated with nonalcoholic steatohepatitis (NASH). However, demonstration of hepatic endotoxin exposure is challenging due to the inaccessibility of the portal circulation. Furthermore, reliable measurement of the relatively low endotoxin levels in plasma of patients with liver disease and subsequent interpretation remain difficult. Goals In this study, we used the EndoCab assay that measures endogenous antibodies to the core region of endotoxin to estimate hepatic endotoxin exposure over time. Study IgG levels against endotoxin were measured in peripheral plasma obtained from 21 severely obese patients with NASH and 9 severely obese patients with healthy livers. Results Plasma IgG levels against endotoxin were significantly elevated in patients with NASH compared with patients with healthy livers (48±63 GMU/mL vs. 10±13 GMU/mL). Moreover, these IgG levels progressively increased with NASH grade (grade 1 29±37; grade 2 58±51; grade 3 84±132 GMU/mL, P<0.05). There was no relation between plasma IgG levels and NASH stage. Conclusions Plasma IgG levels against endotoxin were found to be increased in biopsy-proven human NASH and increased with aggravated inflammation in NASH, suggesting a relationship between chronic endotoxin exposure and the severity of human NASH.

Effects of Liver Resection on Hepatic Short-Chain Fatty Acid Metabolism in Humans

Aim To determine whether acute loss of liver tissue affects hepatic short-chain fatty acid (SCFA) clearance. Methods Blood was sampled from the radial artery, portal vein, and hepatic vein before and after hepatic resection in 30 patients undergoing partial liver resection. Plasma SCFA levels were measured by liquid chromatography-mass spectrometry. SCFA exchange across gut and liver was calculated from arteriovenous differences and plasma flow. Liver volume was estimated by CT liver volumetry. Results The gut produced significant amounts of acetate, propionate, and butyrate (39.4±13.5, 6.2±1.3, and 9.5±2.6 μmol·kgbw-1·h-1), which did not change after partial hepatectomy (p = 0.67, p = 0.59 and p = 0.24). Hepatic propionate uptake did not differ significantly before and after resection (-6.4±1.4 vs. -8.4±1.5 μmol·kgbw-1·h-1, p = 0.49). Hepatic acetate and butyrate uptake increased significantly upon partial liver resection (acetate: -35.1±13.0 vs. -39.6±9.4 μmol·kgbw-1·h-1, p = 0.0011; butyrate: -9.9±2.7 vs. -11.5±2.4 μmol·kgbw-1·h-1, p = 0.0006). Arterial SCFA concentrations were not different before and after partial liver resection (acetate: 176.9±17.3 vs. 142.3±12.5 μmol/L, p = 0.18; propionate: 7.2±1.4 vs. 5.6±0.6 μmol/L, p = 0.38; butyrate: 4.3±0.7 vs. 3.6±0.6 μmol/L, p = 0.73). Conclusion The liver maintains its capacity to clear acetate, propionate, and butyrate from the portal blood upon acute loss of liver tissue.

P32 Liver mobilisation during liver resection induces immediate and profound hepatocellular damage and inflammation in humans

Introduction In a recent study we coincidentally showed that mobilisation of the liver was a major cause of liver surgery-induced damage. The magnitude of and mechanisms by which this damage occurs are unknown. Aim (A) To determine the relative contribution of mobilisation during liver surgery to liver damage and (B) To examine whether there is an association between mobilisation-induced liver damage and liver inflammation. Method Consecutive patients undergoing liver surgery requiring full mobilisation of the right hemi-liver were included. Plasma samples and liver biopsies were obtained immediately after induction, prior to and directly after liver mobilisation, and after liver transection. Liver Fatty Acid Binding Protein (L-FABP) and alanine aminotranferase (ALAT) were analysed as markers of hepatocyte injury. Specimens were stained by immunohistochemistry for myeloperoxidase (MPO), human neutrophil peptide (HNP), and caspase-3-mediated cleavage generated neo-epitope of CK18 (M30). Gene expression of interleukin (IL) 1β, 6 and 8, and intercellular adhesion molecule (ICAM) were analysed by q-RT-PCR. Results Nineteen patients were included (11M/8F, median age 64 years [30–79]) who underwent major liver surgery. L-FABP levels increased significantly during liver mobilisation (from 91.7 ng/ml [11.4–2212.5 ng/ml] to 1014.4 ng/ml [141.4–8986.1 ng/ml], p<0.001) and did not increase significantly thereafter (1315.2 ng/ml [67.0–20 099.2 ng/ml], p=0.75). L-FABP levels after ≥60 min mobilisation time were significantly higher when compared to ≥60 min mobilisation (1679.7 ng/ml vs 645.9 ng/ml, p=0.04). ALAT levels increased significantly from 26 IU/l [13–147] before to 130 IU/l [74–813] after liver mobilisation and to 275 IU/l [13–1352] after transection (all p<0.05). Liver mobilisation increased the numbers of positive cells in staining for MPO (p=0.0007), HNP (p=0.03), and M30 (p=0.01), whereas transaction led to no further increase thereafter. Liver mobilisation increased the gene expression of IL1b (p=0.01), IL-6 (p=0.08), IL-8 (p=0.02) and ICAM (p=0.007). Expression increases ranged from 2.8-fold in ICAM to 130-fold in IL-6. After transection, mRNA levels increased even further in IL-6 (p=0.004), IL-8 (p=0.0004) and ICAM (p=0.02), but not IL1b (p=0.32). Conclusion Mobilisation of the liver during surgery induces profound hepatocellular damage and inflammation, which is associated with activation and/or infiltration of immune cells. Given the short half-life of L-FABP (14 min), hepatocyte damage predominantly occurred during mobilisation of the liver and not during transaction. These data produce insight into the mechanisms of mobilisation-induced liver damage, and provide indications for designing interventions aiming at prevention of surgery-induced liver damage in the future.