Trib1 Deficiency Promotes Hyperlipidemia, Inflammation, and Atherosclerosis in LDL Receptor Knockout Mice.

BACKGROUND: Genetic variants at the TRIB1 gene locus are strongly associated with plasma lipid traits and the risk of coronary artery disease in humans. Here, we analyzed the consequences of Trib1 deficiency on lipid metabolism and atherosclerotic lesion formation in atherosclerosis-susceptible Ldlr-/- mice. METHODS: Trib1-/- mice were crossed onto the Ldlr-/- background to generate double-knockout mice (Trib1-/-Ldlr-/-) and fed a semisynthetic, modified AIN76 diet (0.02% cholesterol and 4.3% fat) until 20 weeks of age. RESULTS: Trib1-/-Ldlr-/- mice had profoundly larger (5.8-fold) and more advanced atherosclerotic lesions at the aortic root as compared with Trib1+/+Ldlr-/- controls. Further, we observed significantly elevated plasma total cholesterol and triglyceride levels in Trib1-/-Ldlr-/- mice, resulting from higher VLDL (very-low-density lipoprotein) secretion. Lipidomics analysis revealed that loss of Trib1 altered hepatic lipid composition, including the accumulation of cholesterol and proinflammatory ceramide species, which was accompanied by signs of hepatic inflammation and injury. Concomitantly, we detected higher plasma levels of IL (interleukin)-6 and LCN2 (lipocalin 2), suggesting increased systemic inflammation in Trib1-/-Ldlr-/- mice. Hepatic transcriptome analysis demonstrated significant upregulation of key genes controlling lipid metabolism and inflammation in Trib1-/-Ldlr-/- mice. Further experiments suggested that these effects may be mediated through pathways involving a C/EPB (CCAAT/enhancer binding protein)-PPARγ (peroxisome proliferator-activated receptor γ) axis and JNK (c-Jun N-terminal kinase) signaling. CONCLUSIONS: We provide experimental evidence that Trib1 deficiency promotes atherosclerotic lesion formation in a complex manner that includes the modulation of lipid metabolism and inflammation.

Tribbles homolog 1 deficiency modulates function and polarization of murine bone marrow-derived macrophages.

Macrophages are essential for innate immunity and inflammatory responses and differentiate into various functional phenotypes. Tribbles homolog 1 (Trib1), a member of the mammalian Tribbles homolog pseudokinase family, has been implicated in regulation of cell differentiation, proliferation, and metabolism, but its role in macrophage biology has not been fully elucidated. Here, we investigated the consequences of Trib1 deficiency on macrophage functions and M1/M2 polarization. Bone marrow-derived macrophages (BMDMs) from Trib1-deficient (Trib1-/-) mice exhibited elevated phagocytic capacity, correlating with up-regulation of several scavenger receptors. Concomitantly, uptake of modified low-density lipoprotein was increased in Trib1-/- BMDMs. Trib1-/- macrophages also exhibited diminished migration in the presence of the chemokine MCP-1, associated with reduced expression of the MCP-1 receptor Ccr2 Furthermore, Trib1 deficiency attenuated the response of BMDMs to both M1 and M2 stimuli; induction of the M1-marker genes Il6, Il1b, and Nos2 upon LPS/IFNγ stimulation and of the M2-marker genes Cd206, Fizz1, and Arg1 upon IL-4 stimulation was reduced. Functionally, Trib1 deficiency decreased secretion of proinflammatory cytokines (IL-6, TNFα, IL-1ß, and CXCL1) and reduced nitric oxide and reactive oxygen species production in M1-polarized macrophages. Supporting the attenuated M2 phenotype, IL-4-stimulated Trib1-/- macrophages secreted less IL-10 and TGFß. Mechanistically, Trib1-/- BMDMs displayed lower levels of Janus kinase 1 (JAK1), resulting in reduced activation of LPS/IFNγ-mediated STAT1 signaling. Likewise, decreased levels of JAK1 along with lower activation of STAT6 and STAT3 were observed in M2-polarized Trib1-/- BMDMs. Our findings suggest that Trib1 extensively controls macrophage M1/M2 polarization via the JAK/STAT signaling pathway.

Leptin dose-dependently decreases atherosclerosis by attenuation of hypercholesterolemia and induction of adiponectin.

OBJECTIVES: Conflicting evidence concerning leptin in atherosclerosis has been published. Furthermore, dose-dependent effects of leptin on atherogenesis have not been studied. METHODS: Leptin-deficient low-density lipoprotein receptor (LDLR) knockout (LDLR(-/-);ob/ob) mice were treated with saline, 0.1, 0.5, or 3.0mg/kg body weight (BW)/d recombinant leptin over 12weeks starting at 8weeks of age. Aortic root and brachiocephalic artery (BCA) atherosclerotic lesions were analyzed by oil red O staining. Furthermore, glucose homeostasis, lipid metabolism, and liver function including tissue studies were assessed in all animals. RESULTS: Leptin treatment dose-dependently decreased BW in LDLR(-/-);ob/ob mice as compared to saline. Mice in the 0.1 and 0.5mg/kgBW/d groups remained heavier (i.e. subphysiological leptin dose) and in the 3.0mg/kgBW/d group had similar weight (i.e. physiological leptin dose) as compared to non-leptin-deficient LDLR(-/-) animals. Recombinant leptin dose-dependently reduced plaque area in the aortic root and the BCA by 36% and 58%, respectively. Leptin-mediated reductions of plasma total and LDL-cholesterol (Chol) remained independent predictors for aortic root plaque area. Chol content in liver, as well as hepatic expression of key lipid and proinflammatory genes, were dose-dependently regulated by leptin. Furthermore, leptin treatment increased circulating levels and adipose tissue mRNA expression of the adipokine adiponectin. CONCLUSIONS: Leptin administration within the subphysiological to physiological range diminishes atherosclerotic lesions. Leptin appears to mediate its antiatherogenic effects indirectly through reduction of hypercholesterolemia and liver steatosis, as well as upregulation of insulin-sensitizing and atheroprotective adiponectin.

Problematic mobile phone use: Validity and reliability of the Problematic Use of Mobile Phone (PUMP) Scale in a German sample.

BACKGROUND: Mobile phones are ubiquitous in everyday life. Scientific studies on the problematic use of mobile phones have given initial indications of negative consequences, such as increased depression and anxiety rates and reduced sleep quality. The Problematic Use of Mobile Phone (PUMP) scale is a well evaluated, 20-item questionnaire, but a German version of the scale is still lacking. METHOD: An online sample (n = 723, age 27.8 ± 11.2 years, 25.2% men) completed a German translation of the PUMP scale (PUMP-D). We conducted standard item analyses and calculated internal consistency and retest reliability. An exploratory (EFA) and a confirmatory factor analysis (CFA) were conducted using a random split of the sample, and correlations with the self-estimated time of mobile phone usage and a global self-rating of patterns of problematic use were computed. Additionally, a second sample (n = 256, age 25.0 ± 8.8 years, 34.0% men) completed the paper version of the PUMP-D scale twice to determine the 14-day retest reliability. RESULTS: The item-total correlations ranged from r = 0.35 (p < 0.001) to r = 0.75 (p < .001). The internal consistency was α = 0.90. The self-estimated time of usage correlated with the total value of the PUMP-D scale at r = 0.50 (p < .001). The EFA resulted in a single factor, which explained 36% of the variance. The CFA of the showed a moderate fit. The two-week retest reliability in the second sample was r tt = 0.87 (p < .001). DISCUSSION: The German translation of the PUMP-D demonstrated a single factor structure, good psychometric properties and can be used in further research.

Leptin decreases circulating inflammatory IL-6 and MCP-1 in mice.

Leptin influences inflammation and immune response. Dose-dependent effects of leptin on biomarkers of inflammation have not been studied in vivo, so far. Leptin-deficient low-density lipoprotein receptor (LDLR) knockout (LDLR-/- ;ob/ob) female mice were treated with three different leptin doses or saline for 12 weeks. The effect of leptin on plasma interleukin (IL)-6 and monocyte chemoattractant protein (MCP)-1 concentrations and Il-6 and Mcp-1 mRNA expression in vivo were assessed. Macrophage infiltration in epididymal adipose tissue (epiAT) after leptin treatment was determined by quantitative immunohistochemical analysis. Aortic root atherosclerotic lesions were analyzed by oil red O staining. Mean plasma IL-6 and MCP-1 decreased significantly in the 3.0 mg/kg BW/day group as compared to control mice (both P < 0.01). Messenger RNA expression of Il-6 and Mcp-1 was significantly down-regulated by leptin treatment in different adipose tissues in vivo. Characteristic crown-like structures formed by adipose tissue macrophages were significantly reduced by leptin treatment in epiAT. Recombinant leptin dose-dependently diminished plaque area in the aortic root. Leptin administration within the subphysiological to physiological range diminishes circulating pro-inflammatory IL-6 and MCP-1. Reduction of Il-6 and Mcp-1 gene expression in adipose tissue, as well as decreased adipose tissue macrophage infiltration might contribute. © 2018 BioFactors, 45(1):43-48, 2019.

Psychometric Evaluation of the Nine-Item Problematic Internet Use Questionnaire (PIUQ-9) in Nine European Samples of Internet Users.

Objectives: The nine-item Problematic Internet Use Questionnaire (PIUQ-9) is a brief self-report screening instrument for problematic internet use. The main objective of the present study was to explore the psychometric properties of the PIUQ-9 among nine different language-based samples of European internet users (Italian, German, French, Polish, Turkish, Hungarian, English, and Greek). Methods: The total sample comprised 5,593 internet users (38.1% men), aged between 18 and 87 years (M = 25.81; SD = 8.61). Via online recruitment, participants completed the PIUQ-9, the Brief Symptom Inventory (BSI) and items about time spent online. Results: Confirmatory factor analysis demonstrated that the bifactor model with one general factor (i.e., general problem) and two-specific factors (i.e., obsession and neglect + control disorder) yielded acceptable or good fit indices in all subsamples except for one. The common variance index in the bifactor model indicated that the general problem factor explained from 57.0 to 76.5% of common variance, which supports the presence of a strong global factor. According to the multiple indicators multiple causes (MIMIC) model, psychiatric symptoms had a moderate-to-strong direct effect on the general problem factor in all subsamples, ranging from ß = 0.28 to ß = 0.52 supporting the construct validity of the scale. Furthermore, in a majority of the subsamples, time spent online during the weekend had considerably higher effect sizes on the general problem factor than time spent online during weekdays. Conclusion: The present study highlights the appropriate psychometric properties of the PIUQ-9 across a number of European languages and cultures.

Validation of the Internet Gaming Disorder Questionnaire in a Sample of Adult German-Speaking Internet Gamers.

With the inclusion of Internet Gaming Disorder (IGD) in the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders comes the need for a reliable and valid questionnaire to assess the diagnosis. The Internet Gaming Disorder Questionnaire (IGDQ) is a short tool that measures IGD. Our study aimed at investigating its psychometric properties in a sample of German gamers. Eight hundred ninety-four Internet game players (mean age: 26.5 ± 8.5 years, range: 18-75 years, 87.36% male) completed an online version of the IGDQ and the Compulsive Internet Use Scale (CIUS) and provided information on their Internet and gaming use. Item and reliability analyses were computed. To investigate the component structure, the sample was randomly divided into two subsamples. A maximum likelihood factor analysis was conducted for one subsample and a confirmatory factor analysis (CFA) for the other subsample. The IGDQ had a Cronbach's alpha of 0.70. The IGDQ score correlated with the CIUS score (r = 0.59) and the time spent playing (r = 0.24). The maximum likelihood factor analysis extracted one component, explaining 30.26% of the variance, which was confirmed by the CFA. The correlation of the IGDQ score with the CIUS score is a first indicator that the IGDQ allows for valid interpretations. In all, 7.94% of the gamers met the criteria for IGD.

Attentional bias in excessive Internet gamers: Experimental investigations using an addiction Stroop and a visual probe.

Background and aims Internet Gaming Disorder is included in the Diagnostic and statistical manual of mental disorders (5th edition) as a disorder that merits further research. The diagnostic criteria are based on those for Substance Use Disorder and Gambling Disorder. Excessive gamblers and persons with Substance Use Disorder show attentional biases towards stimuli related to their addictions. We investigated whether excessive Internet gamers show a similar attentional bias, by using two established experimental paradigms. Methods We measured reaction times of excessive Internet gamers and non-gamers (N = 51, 23.7 ± 2.7 years) by using an addiction Stroop with computer-related and neutral words, as well as a visual probe with computer-related and neutral pictures. Mixed design analyses of variance with the between-subjects factor group (gamer/non-gamer) and the within-subjects factor stimulus type (computer-related/neutral) were calculated for the reaction times as well as for valence and familiarity ratings of the stimulus material. Results In the addiction Stroop, an interaction for group × word type was found: Only gamers showed longer reaction times to computer-related words compared to neutral words, thus exhibiting an attentional bias. In the visual probe, no differences in reaction time between computer-related and neutral pictures were found in either group, but the gamers were faster overall. Conclusions An attentional bias towards computer-related stimuli was found in excessive Internet gamers, by using an addiction Stroop but not by using a visual probe. A possible explanation for the discrepancy could lie in the fact that the visual probe may have been too easy for the gamers.

Using two web-based addiction Stroops to measure the attentional bias in adults with Internet Gaming Disorder.

Background and aims People with substance abuse and pathological gamblers show an attentional bias. In a laboratory setting, we found an attentional bias using an addiction Stroop in adults with Internet Gaming Disorder (IGD). We aimed at investigating this effect using two web-based experiments. Methods Study 1: Gamers with IGD, casual gamers, and non-gamers (N = 81, 28.1 ± 7.8 years) completed a web-based addiction Stroop with a fully randomized word order. They saw computer-related and neutral words in four colors and indicated the word color via keypress. Study 2: Gamers with IGD, casual gamers, and non-gamers (N = 87, 23.4 ± 5.1 years) completed a web-based addiction Stroop and a classical Stroop (incongruent color and neutral words), which both had a block design. We expected that in both studies, only the gamers with IGD would react more slowly to computer-related words in the addiction Stroop. All groups were expected to react more slowly to incongruent color words in the classical Stroop. Results In neither study did the gamers with IGD differ in their reaction times to computer-related words compared to neutral words. In Study 2, all groups reacted more slowly to incongruent color words than to neutral words confirming the validity of the online reaction time assessment. Discussion Gamers with IGD did not show a significant attentional bias. IGD may differ from substance abuse and pathological gambling in this respect; alternatively experimenting on the Internet may have introduced error variance that made it harder to detect a bias.