Plasma levels of glucagon but not GLP-1 are elevated in response to inflammation in humans.

OBJECTIVE: Glucagon and glucagon-like peptide-1 (GLP-1) originate from the common precursor, proglucagon, and their plasma concentrations have been reported to be increased during inflammatory conditions. Increased blood glucose levels are frequently observed in septic patients, and therefore we hypothesized that glucagon, but not GLP-1, is increased in individuals with inflammation. DESIGN: Prospective longitudinal cohort study. MATERIALS AND METHODS: We measured glucagon and GLP-1 in plasma sampled consecutively in three cohorts consisting of patients with infective endocarditis (n = 16), urosepsis (n = 28) and post-operative inflammation following percutaneous aortic valve implantation or thoracic endovascular aortic repair (n = 5). Correlations between C-reactive protein (CRP), a marker of systemic inflammation, and glucagon and GLP-1 concentrations were investigated. Additionally, glucagon and GLP-1 concentrations were measured after a bolus infusion of lipopolysaccharide (LPS, 1 ng/kg) in nine healthy young males. RESULTS: Glucagon and CRP were positively and significantly correlated (r = 0.27; P = 0.0003), whereas no significant association between GLP-1 and CRP was found (r = 0.08, P = 0.30). LPS infusion resulted in acute systemic inflammation reflected by increased temperature, pulse, tumor necrosis factor-α (TNFα), interleukin-6 (IL-6) and concomitantly increased concentrations of glucagon (P < 0.05) but not GLP-1. CONCLUSIONS: Systemic inflammation caused by bacterial infections or developed as a non-infected condition is associated with increased plasma concentration of glucagon, but not GLP-1. Hyperglucagonemia may contribute to the impaired glucose control in patients with systemic inflammatory diseases.

In vivo-induced size transformation of cerium oxide nanoparticles in both lung and liver does not affect long-term hepatic accumulation following pulmonary exposure.

Recent findings show that cerium oxide (CeO2) nanoparticles may undergo in vivo-induced size transformation with the formation of smaller particles that could result in a higher translocation following pulmonary exposure compared to virtually insoluble particles, like titanium dioxide (TiO2). Therefore, we compared liver deposition of CeO2 and TiO2 nanoparticles of similar primary sizes 1, 28 or 180 days after intratracheal instillation of 162 µg of NPs in female C57BL/6 mice. Mice exposed to 162 µg CeO2 or TiO2 nanoparticles by intravenous injection or oral gavage were included as reference groups to assess the amount of NPs that reach the liver bypassing the lungs and the translocation of NPs from the gastrointestinal tract to the liver, respectively. Pulmonary deposited CeO2 nanoparticles were detected in the liver 28 and 180 days post-exposure and TiO2 nanoparticles 180 days post-exposure as determined by darkfield imaging and by the quantification of Ce and Ti mass concentration by inductively coupled plasma-mass spectrometry (ICP-MS). Ce and Ti concentrations increased over time and 180 days post-exposure the translocation to the liver was 2.87 ± 3.37% and 1.24 ± 1.98% of the initial pulmonary dose, respectively. Single particle ICP-MS showed that the size of CeO2 nanoparticles in both lung and liver tissue decreased over time. No nanoparticles were detected in the liver following oral gavage. Our results suggest that pulmonary deposited CeO2 and TiO2 nanoparticles translocate to the liver with similar calculated translocation rates despite their different chemical composition and shape. The observed particle size distributions of CeO2 nanoparticles indicate in vivo processing over time both in lung and liver. The fact that no particles were detected in the liver following oral exposure showed that direct translocation of nanoparticles from lung to the systemic circulation was the most important route of translocation for pulmonary deposited particles.

Primary genotoxicity in the liver following pulmonary exposure to carbon black nanoparticles in mice.

BACKGROUND: Little is known about the mechanism underlying the genotoxicity observed in the liver following pulmonary exposure to carbon black (CB) nanoparticles (NPs). The genotoxicity could be caused by the presence of translocated particles or by circulating inflammatory mediators released during pulmonary inflammation and acute-phase response. To address this, we evaluated induction of pulmonary inflammation, pulmonary and hepatic acute-phase response and genotoxicity following exposure to titanium dioxide (TiO2), cerium oxide (CeO2) or CB NPs. Female C57BL/6 mice were exposed by intratracheal instillation, intravenous injection or oral gavage to a single dose of 162 µg NPs/mouse and terminated 1, 28 or 180 days post-exposure alongside vehicle control. RESULTS: Liver DNA damage assessed by the Comet Assay was observed after intravenous injection and intratracheal instillation of CB NPs but not after exposure to TiO2 or CeO2. Intratracheal exposure to NPs resulted in pulmonary inflammation in terms of increased neutrophils influx for all NPs 1 and 28 days post-exposure. Persistent pulmonary acute phase response was detected for all NPs at all three time points while only a transient induction of hepatic acute phase response was observed. All 3 materials were detected in the liver by enhanced darkfield microscopy up to 180 days post-exposure. In contrast to TiO2 and CeO2 NPs, CB NPs generated ROS in an acellular assay. CONCLUSIONS: Our results suggest that the observed hepatic DNA damage following intravenous and intratracheal dosing with CB NPs was caused by the presence of translocated, ROS-generating, particles detected in the liver rather than by the secondary effects of pulmonary inflammation or hepatic acute phase response.