Targeted Deletion of Fibrinogen Like Protein 1 Reveals a Novel Role in Energy Substrate Utilization

Fibrinogen like protein 1(Fgl1) is a secreted protein with mitogenic activity on primary hepatocytes. Fgl1 is expressed in the liver and its expression is enhanced following acute liver injury. In animals with acute liver failure, administration of recombinant Fgl1 results in decreased mortality supporting the notion that Fgl1 stimulates hepatocyte proliferation and/or protects hepatocytes from injury. However, because Fgl1 is secreted and detected in the plasma, it is possible that the role of Fgl1 extends far beyond its effect on hepatocytes. In this study, we show that Fgl1 is additionally expressed in brown adipose tissue. We find that signals elaborated following liver injury also enhance the expression of Fgl1 in brown adipose tissue suggesting that there is a cross talk between the injured liver and adipose tissues. To identify extra hepatic effects, we generated Fgl1 deficient mice. These mice exhibit a phenotype suggestive of a global metabolic defect: Fgl1 null mice are heavier than wild type mates, have abnormal plasma lipid profiles, fasting hyperglycemia with enhanced gluconeogenesis and exhibit differences in white and brown adipose tissue morphology when compared to wild types. Because Fgl1 shares structural similarity to Angiopoietin like factors 2, 3, 4 and 6 which regulate lipid metabolism and energy utilization, we postulate that Fgl1 is a member of an emerging group of proteins with key roles in metabolism and liver regeneration

Risk Factors for Pediatric Asthma Readmissions: A Systematic Review

To systematically review the literature on pediatric asthma readmission risk factors. We searched PubMed/MEDLINE, CINAHL, Scopus, PsycINFO, and Cochrane Central Register of Controlled Trials for published articles (through November 2019) on pediatric asthma readmission risk factors. Two authors independently screened titles and abstracts and consensus was reached on disagreements. Full-text articles were reviewed and inclusion criteria applied. For articles meeting inclusion criteria, authors abstracted data on study design, patient characteristics, and outcomes, and 4 authors assessed bias risk. Of 5749 abstracts, 74 met inclusion criteria. Study designs, patient populations, and outcome measures were highly heterogeneous. Risk factors consistently associated with early readmissions (≤30 days) included prolonged length of stay (OR range, 1.1-1.6) and chronic comorbidities (1.7-3.2). Risk factors associated with late readmissions (>30 days) included female sex (1.1-1.6), chronic comorbidities (1.5-2), summer discharge (1.5-1.8), and prolonged length of stay (1.04-1.7). Across both readmission intervals, prior asthma admission was the most consistent readmission predictor (1.3-5.4). Pediatric asthma readmission risk factors depend on the readmission interval chosen. Prior hospitalization, length of stay, sex, and chronic comorbidities were consistently associated with both early and late readmissions. CRD42018107601

Length and tissue mass of <i>Fgl1^+/+</i> and <i>Fgl1^−/−</i> mice.

<p>(n = 5 for both cohorts except for liver (*) where n = 9).</p

The liver in the Fgl1 knockout mouse.

<p>A) Fgl1 transcript is absent in the livers of the knockout mouse pre and post PH. Note the expected induction of Fgl1 in the wild type mouse after PH (P<0.01 for Fgl1 at baseline and 48 h after PH, n = 3 per group) B) Fgl1 protein is absent in the livers of the knockout mouse before and after PH while it is detectable at baseline and induced after PH in the wild type mouse. C) <i>Fgl1^−/−</i> mice are larger than wild type mates as early as three weeks after birth (P<0.0001, n = 5 for each group). D) Representative graph of change in weight over time for <i>Fgl1^+/+</i> (n = 8 for first 4 weeks, n = 4 for last three weeks) and <i>Fgl1^−/−</i> (n = 9 for first 4 weeks and n = 8 for last three weeks). E) Liver mass is not different between <i>Fgl1^+/+</i> and <i>Fgl1^−/−</i> mice (n = 9 for each group). F) Liver weight to body weight ratio is smaller for <i>Fgl1^−/−</i> mice (P = 0.008, n = 9). G) Marked lipid accumulation in the livers of <i>Fgl1^−/−</i> mice after PH. Top: gross images of representative livers from <i>Fgl1^+/+</i> (left) and <i>Fgl1^−/−</i> (right). Arrows indicate remnant liver lobes. Middle: H&E images at 40× magnification of liver sections from <i>Fgl1^+/+</i> and <i>Fgl1^−/−</i> mice at 48 h post PH and bottom: similar H&E images at 96 h post PH. Note the resolution of steatosis in the <i>Fgl1^−/−</i> mouse by 96 h after PH. H) Triglyceride (TG) content of liver extracts from <i>Fgl1^+/+</i> and <i>Fgl1^−/−</i> mice before and after PH. The difference between <i>Fgl1^−/−</i> and <i>Fgl1^+/+</i> at 48 h after PH is significant (P = 0.014, n = 3–5 per cohort for experiments). I) mRNA levels of lipid regulatory genes at 48 h after PH (P = 0.011, 0.014 and 0.037 respectively for PPARα, PPARδ and FATP5 but is otherwise non significant). n = 4 for <i>Fgl1^+/+</i> except FATP5 where n = 3 per group. n = 5 for <i>Fgl1^−/−</i>.</p

Food intake and indirect calorimetry.

<p>Scatter plot of average food intake versus average weight for individually housed <i>Fgl1^+/+</i> (blue squares, n = 4) and <i>Fgl1^−/−</i>(red circles, n = 8) taken daily over an 18 day period. Note that <i>Fgl1^−/−</i> remain larger that wild types for the duration of the experiment. B and C) Indirect calorimetric values for VO₂ and VCO₂ respectively and D) RER. The RER is significant irrespective of day and night cycles (P = 0.04 and 0.016 respectively) and over the entire 24 h (P = 0.019). E) Heat generation is not significantly different and F) activity is not different between the Fgl1 containing and deficient mice. n = 6 for <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0058084#pone-0058084-g006" target="_blank">Figures 6B to 6F</a>.</p

Fgl1 in hepatic and brown adipose tissue.

<p>A) mRNA levels of Fgl1 in the liver at baseline (0 h) and at 24 h and 48 h after PH. Note the increased expression after PH. P = 0.002 between 0 h and 24 h and less than 0.0001 between 0 h and 48 h after PH. The difference between levels at 24 h and 48 h is not significant. B) mRNA levels of Fgl1 in brown adipose tissue (BAT) at baseline and at 24 h and 48 h after partial hepatectomy. Fgl1 is detectable in BAT prior to injury but expression is enhanced after PH. P = 0.026 between 0 and 24 h and P = 0.013 between 0 and 48 h after PH. The difference between levels at 24 h and 48 h is not significant. n = 3 for samples in 1A and B. C) Gel electrophoresis of amplified cDNA from BAT at baseline and at 24 h and 48 h after PH. Cyclophilin A is the loading control. D) Comparison of BAT Fgl1 levels pre and post PH with hepatic Fgl1 levels at baseline. Samples are normalized to hepatic Fgl1 at 100%. Fgl1 in BAT is 0.4%, 2.6% and 3.4% of hepatic levels at baseline and at 24 h and 48 h after PH (P<0.0001).</p

Glucose metabolism in the Fgl1 null mouse.

<p>A) <i>Fgl1^−/−</i> mice have fasting hyperglycemia (P = 0.005, n = 10 for <i>Fgl1^+/+</i> and n = 8 for <i>Fgl1^−/−</i>). B) Glucose tolerance tests of fasted 3 month old mouse. The graph represents a plot of plasma glucose versus time after i.p. administration of glucose. The superimposed panel represents plots of average area under the curve (AUC) for each mouse. The baseline was set as the mean pre-glucose administration plasma level. The difference is glucose levels as determined from the AUC is significant (P = 0.002, n = 4 per group). C) Insulin tolerance test on 3 month old fasted mouse shows a similar rate of decline of glucose levels between the <i>Fgl1^+/+</i> and <i>Fgl1^−/−</i> mice. AUC calculations after normalizing for baseline glucose for the first 45 min of the test shows no differences between Fgl1 containing and deficient mice (n = 5 per group). D) Insulin levels are not different between <i>Fgl1^+/+</i> and <i>Fgl1^−/−</i> mice. E) HOMA scores are not different for <i>Fgl1^+/+</i> and <i>Fgl1^−/−</i> (n = 5 for <i>Fgl1^+/+</i> and 4 for <i>Fgl1^−/−</i>). F) Graph of glucose levels following administration of pyruvate to fasted mice. Inset is AUC calculation which shows a difference in glucose levels over the duration of the experiment (P = 0.029, n = 5 per group).</p

Structure, content and activity of adipose tissues in the Fgl1 null mouse.

<p>A) Representative H&E stains (40× magnification) of brown adipose tissue. Lipid droplets are larger in <i>Fgl1^−/−</i> mice. B) Quantitation of lipid droplet size show significant difference between <i>Fgl1^+/+</i> and <i>Fgl1^−/−</i> mice (P = 0.011, n = 5 per group). C) Expression of brown adipose genes. Note the paradoxical up regulation of DiO2 and UCP1 (P = 0.002 and 0.0001 respectively. n = 11 per group except for Perilipin and HSL where n = 5 and 6 respectively). D) ¹⁸FDG incorporation into BAT. The % uptake represents the uptake of injected dose per gram of tissue. Note the marked decrease in radioisotope uptake in BAT (P = 0.05, n = 5 per group). E). Representative H&E stains (40× magnification) of white adipose tissue. Lipid droplets are larger in <i>Fgl1^−/−</i> mice. F) Quantitation of number of cells per HPF shows smaller number of white adipose cells in <i>Fgl1^−/−</i> (P = 0.005, n = 5). G) Expression of white adipose genes. Glut4, leptin and perilipin are significantly down regulated (*) with a P<0.04 for each. P for ATGL (#) is 0.06. n = 4–6 mice per group.</p

Plasma lipid, cholesterol and free fatty acid levels in the Fgl1 null mouse.

<p>A) There is no significant difference in steady state plasma TG levels of <i>Fgl1^+/+</i> and <i>Fgl1^−/−</i> mice. B) Free fatty acid levels are decreased in the Fgl1 null mouse (P = 0.001). C and D) Plasma cholesterol levels are levels are lower as determined by total cholesterol (P = 0.003) and FPLC analysis. n = 5 per group.</p