Activation of proteinase 3 contributes to Non-alcoholic Fatty Liver Disease (NAFLD) and insulin resistance

Contains fulltext : 169891.pdf (publisher's version ) (Open Access)Activation of inflammatory pathways is known to accompany development of obesity-induced non-alcoholic fatty liver disease (NAFLD), insulin resistance and type 2 diabetes. In addition to caspase-1, the neutrophil serine proteases proteinase 3, neutrophil elastase and cathepsin G are able to process the inactive pro-inflammatory mediators IL-1beta and IL-18 to their bioactive forms, thereby regulating inflammatory responses. In the present study, we investigated whether proteinase 3 is involved in obesity-induced development of insulin resistance and NAFLD. We investigated the development of NAFLD and insulin resistance in mice deficient for neutrophil elastase/proteinase 3 and neutrophil elastase/cathepsin G and in wild-type mice treated with the neutrophil serine proteinase inhibitor human alpha-1 antitrypsin. Expression profiling of metabolically relevant tissues obtained from insulin resistant mice showed that expression of proteinase 3 was specifically upregulated in the liver, whereas neutrophil elastase, cathepsin G and caspase-1 were not. Neutrophil elastase/proteinase 3 deficient mice showed strongly reduced levels of lipids in the liver after fed a high fat diet. Moreover, these mice were resistant to high fat diet-induced weight gain, inflammation and insulin resistance. Injection of proteinase 3 exacerbated insulin resistance in caspase-1(-/-) mice, indicating that proteinase 3 acts independently of caspase-1. Treatment with alpha-1 antitrypsin during the last 10 days of a 16 week high fat diet reduced hepatic lipid content and decreased fasting glucose levels. We conclude that proteinase 3 is involved in NAFLD and insulin resistance and that inhibition of proteinase 3 may have therapeutic potential

Unexpected diversity in socially synchronized rhythms of shorebirds

The behavioural rhythms of organisms are thought to be under strong selection, influenced by the rhythmicity of the environment1, 2, 3, 4. Such behavioural rhythms are well studied in isolated individuals under laboratory conditions1, 5, but free-living individuals have to temporally synchronize their activities with those of others, including potential mates, competitors, prey and predators6, 7, 8, 9, 10. Individuals can temporally segregate their daily activities (for example, prey avoiding predators, subordinates avoiding dominants) or synchronize their activities (for example, group foraging, communal defence, pairs reproducing or caring for offspring)6, 7, 8, 9, 11. The behavioural rhythms that emerge from such social synchronization and the underlying evolutionary and ecological drivers that shape them remain poorly understood5, 6, 7, 9. Here we investigate these rhythms in the context of biparental care, a particularly sensitive phase of social synchronization12 where pair members potentially compromise their individual rhythms. Using data from 729 nests of 91 populations of 32 biparentally incubating shorebird species, where parents synchronize to achieve continuous coverage of developing eggs, we report remarkable within- and between-species diversity in incubation rhythms. Between species, the median length of one parent’s incubation bout varied from 1–19 h, whereas period length—the time in which a parent’s probability to incubate cycles once between its highest and lowest value—varied from 6–43 h. The length of incubation bouts was unrelated to variables reflecting energetic demands, but species relying on crypsis (the ability to avoid detection by other animals) had longer incubation bouts than those that are readily visible or who actively protect their nest against predators. Rhythms entrainable to the 24-h light–dark cycle were less prevalent at high latitudes and absent in 18 species. Our results indicate that even under similar environmental conditions and despite 24-h environmental cues, social synchronization can generate far more diverse behavioural rhythms than expected from studies of individuals in captivity5, 6, 7, 9. The risk of predation, not the risk of starvation, may be a key factor underlying the diversity in these rhythms

Prednisolone induces the Wnt signalling pathway in 3T3-L1 adipocytes

Contains fulltext : 117166.pdf (publisher's version ) (Open Access)Synthetic glucocorticoids are potent anti-inflammatory drugs but show dose-dependent metabolic side effects such as the development of insulin resistance and obesity. The precise mechanisms involved in these glucocorticoid-induced side effects, and especially the participation of adipose tissue in this are not completely understood. We used a combination of transcriptomics, antibody arrays and bioinformatics approaches to characterize prednisolone-induced alterations in gene expression and adipokine secretion, which could underlie metabolic dysfunction in 3T3-L1 adipocytes. Several pathways, including cytokine signalling, Akt signalling, and Wnt signalling were found to be regulated at multiple levels, showing that these processes are targeted by prednisolone. These results suggest that mechanisms by which prednisolone induce insulin resistance include dysregulation of wnt signalling and immune response processes. These pathways may provide interesting targets for the development of improved glucocorticoids

Activation of Proteinase 3 Contributes to Nonalcoholic Fatty Liver Disease and Insulin Resistance

Abstract Activation of inflammatory pathways is known to accompany development of obesity-induced nonalcoholic fatty liver disease (NAFLD), insulin resistance and type 2 diabetes. In addition to caspase-1, the neutrophil serine proteases proteinase 3, neutrophil elastase and cathepsin G are able to process the inactive proinflammatory mediators interleukin (IL)-1β and IL-18 to their bioactive forms, thereby regulating inflammatory responses. In this study, we investigated whether proteinase 3 is involved in obesity-induced development of insulin resistance and NAFLD. We investigated the development of NAFLD and insulin resistance in mice deficient for neutrophil elastase/proteinase 3 and neutrophil elastase/cathepsin G and in wild-type mice treated with the neutrophil serine proteinase inhibitor human α-1 antitrypsin. Expression profiling of metabolically relevant tissues obtained from insulin-resistant mice showed that expression of proteinase 3 was specifically upregulated in the liver, whereas neutrophil elastase, cathepsin G and caspase-1 were not. Neutrophil elastase/proteinase 3-deficient mice showed strongly reduced levels of lipids in the liver after being fed a high-fat diet. Moreover, these mice were resistant to high-fat-diet-induced weight gain, inflammation and insulin resistance. Injection of proteinase 3 exacerbated insulin resistance in caspase-1−/− mice, indicating that proteinase 3 acts independently of caspase-1. Treatment with α-1 antitrypsin during the last 10 d of a 16-wk high-fat diet reduced hepatic lipid content and decreased fasting glucose levels. We conclude that proteinase 3 is involved in NAFLD and insulin resistance and that inhibition of proteinase 3 may have therapeutic potential

Treatment parameters for both non-arthritic and arthritic mice treated with placebo, prednisolone (10 mg/kg) or ORG 37663 (12 mg/kg) for 21 days.

<p>Both non-arthritic and arthritic mice are treated with placebo, prednisolone (10 mg/kg/day) or ORG 37663 (12 mg/kg/day) for 21 days. Each experimental group consists of 12 mice; in total 36 non-arthritic and 36 arthritic mice were included. Values represent means ± SD during the blood glucose kinetics test except BW, which is represented as means ± SD before the test.</p><p>* Significant difference (p≤0.05) when compared to the placebo-treated group of that same parameter.</p>#<p>Significant difference (p≤0.05) when compared to the placebo-treated non-arthritic mice.</p><p>Treatment parameters for both non-arthritic and arthritic mice treated with placebo, prednisolone (10 mg/kg) or ORG 37663 (12 mg/kg) for 21 days.</p

The formulas used to calculate the concentration <i>vs</i>. time curves and the kinetic parameters in a first order absorption process in an one-compartment model.

<p>C_t, D-[6,6-²H]-glucose concentration at time point t; M_t, fractional contribution of D-[6,6-²H]-glucose at time point t; [glc]_t, blood glucose concentration at time point t. C(0)^ab, initial concentration of D-[6,6-²H]-glucose determined by extrapolation of the absorption period; C(0)^el, initial concentration of D-[6,6-²H]-glucose determined by extrapolation of the elimination period; k^ab, absorption rate constant; k^el, absorption rate constant. D, dose D-[6,6-²H]-glucose administrated; BG, average blood glucose concentration during the test; Ra = EGP.</p><p>The formulas used to calculate the concentration <i>vs</i>. time curves and the kinetic parameters in a first order absorption process in an one-compartment model.</p