Genetic network identifies novel pathways contributing to atherosclerosis susceptibility in the innominate artery

Abstract Background Atherosclerosis, the underlying cause of cardiovascular disease, results from both genetic and environmental factors. Methods In the current study we take a systems-based approach using weighted gene co-expression analysis to identify a candidate pathway of genes related to atherosclerosis. Bioinformatic analyses are performed to identify candidate genes and interactions and several novel genes are characterized using in-vitro studies. Results We identify 1 coexpression module associated with innominate artery atherosclerosis that is also enriched for inflammatory and macrophage gene signatures. Using a series of bioinformatics analysis, we further prioritize the genes in this pathway and identify Cd44 as a critical mediator of the atherosclerosis. We validate our predictions generated by the network analysis using Cd44 knockout mice. Conclusion These results indicate that alterations in Cd44 expression mediate inflammation through a complex transcriptional network involving a number of previously uncharacterized genes

Vegetation Cover Analysis of Hazardous Waste Sites in Utah and Arizona Using Hyperspectral Remote Sensing

This study investigated the usability of hyperspectral remote sensing for characterizing vegetation at hazardous waste sites. The specific objectives of this study were to: (1) estimate leaf-area-index (LAI) of the vegetation using three different methods (i.e., vegetation indices, red-edge positioning (REP), and machine learning regression trees), and (2) map the vegetation cover using machine learning decision trees based on either the scaled reflectance data or mixture tuned matched filtering (MTMF)-derived metrics and vegetation indices. HyMap airborne data (126 bands at 2.3 x 2.3 m spatial resolution), collected over the U. S. Department of Energy uranium processing sites near Monticello, Utah and Monument Valley, Arizona, were used. Grass and shrub species were mixed on an engineered disposal cell cover at the Monticello site while shrub species were dominant in the phytoremediation plantings at the Monument Valley site. Regression trees resulted in the best calibration performance of LAI estimation (R-2 > 0.80. The use of REPs failed to accurately predict LAI (R-2 < 0.2). The use of the MTMF-derived metrics (matched filter scores and infeasibility) and a range of vegetation indices in decision trees improved the vegetation mapping when compared to the decision tree classification using just the scaled reflectance. Results suggest that hyperspectral imagery are useful for characterizing biophysical characteristics (LAI) and vegetation cover on capped hazardous waste sites. However, it is believed that the vegetation mapping would benefit from the use of higher spatial resolution hyperspectral data due to the small size of many of the vegetation patches (<1 m) found on the sites.open111

Responsiveness of cardiometabolic-related microbiota to diet is influenced by host genetics

Intestinal microbial community structure is driven by host genetics in addition to environmental factors such as diet. In comparison with environmental influences, the effect of host genetics on intestinal microbiota, and how host-driven differences alter host metabolism is unclear. Additionally, the interaction between host genetics and diet, and the impact on the intestinal microbiome and possible down-stream effect on host metabolism is not fully understood, but represents another aspects of inter-individual variation in disease risk. The objectives of this study were to investigate how diet and genetic background shape microbial communities, and how these diet- and genetic-driven microbial differences relate to cardiometabolic phenotypes. To determine these effects, we used the 8 progenitor strains of the collaborative cross/diversity outbred mapping panels (C57BL/6J, A/J, NOD/ShiLtJ, NZO/HILtJ, WSB/EiJ, CAST/EiJ, PWK/PhJ, and 129S1/SvImJ). 16s rRNA profiling of enteric microbial communities in addition to the assessment of phenotypes central to cardiometabolic health was conducted under baseline nutritional conditions and in response to diets varying in atherogenic nutrient (fat, cholesterol, cholic acid) composition. These studies revealed strain-driven differences in enteric microbial communities which were retained with dietary intervention. Diet–strain interactions were seen for a core group of cardiometabolic-related microbial taxa. In conclusion, these studies highlight diet and genetically regulated cardiometabolic-related microbial taxa. Furthermore, we demonstrate the progenitor model is useful for nutrigenomic-based studies and screens seeking to investigate the interaction between genetic background and the phenotypic and microbial response to diet.Electronic supplementary materialThe online version of this article (doi:10.1007/s00335-014-9540-0) contains supplementary material, which is available to authorized users

Development and Characterization of Syngeneic Orthotopic Transplant Models of Obesity-Responsive Triple-Negative Breast Cancer in C57BL/6J Mice

Obesity is an established risk and progression factor for triple-negative breast cancer (TNBC), but preclinical studies to delineate the mechanisms underlying the obesity-TNBC link as well as strategies to break that link are constrained by the lack of tumor models syngeneic to obesity-prone mouse strains. C3(1)/SV40 T-antigen (C3-TAg) transgenic mice on an FVB genetic background develop tumors with molecular and pathologic features that closely resemble human TNBC, but FVB mice are resistant to diet-induced obesity (DIO). Herein, we sought to develop transplantable C3-TAg cell lines syngeneic to C57BL/6 mice, an inbred mouse strain that is sensitive to DIO. We backcrossed FVB-Tg(C3-1-TAg)cJeg/JegJ to C57BL/6 mice for ten generations, and spontaneous tumors from those mice were excised and used to generate four clonal cell lines (B6TAg1.02, B6TAg2.03, B6TAg2.10, and B6TAg2.51). We characterized the growth of the four cell lines in both lean and DIO C57BL/6J female mice and performed transcriptomic profiling. Each cell line was readily tumorigenic and had transcriptional profiles that clustered as claudin-low, yet markedly differed from each other in their rate of tumor progression and transcriptomic signatures for key metabolic, immune, and oncogenic signaling pathways. DIO accelerated tumor growth of orthotopically transplanted B6TAg1.02, B6TAg2.03, and B6TAg2.51 cells. Thus, the B6TAg cell lines described herein offer promising and diverse new models to augment the study of DIO-associated TNBC

Genetic network identifies novel pathways contributing to atherosclerosis susceptibility in the innominate artery

Abstract Background Atherosclerosis, the underlying cause of cardiovascular disease, results from both genetic and environmental factors. Methods In the current study we take a systems-based approach using weighted gene co-expression analysis to identify a candidate pathway of genes related to atherosclerosis. Bioinformatic analyses are performed to identify candidate genes and interactions and several novel genes are characterized using in-vitro studies. Results We identify 1 coexpression module associated with innominate artery atherosclerosis that is also enriched for inflammatory and macrophage gene signatures. Using a series of bioinformatics analysis, we further prioritize the genes in this pathway and identify Cd44 as a critical mediator of the atherosclerosis. We validate our predictions generated by the network analysis using Cd44 knockout mice. Conclusion These results indicate that alterations in Cd44 expression mediate inflammation through a complex transcriptional network involving a number of previously uncharacterized genes

Abstract 485: CD44 Deficiency Protects Against Diet-Induced Obesity and Reduces Adipose Tissue Inflammation in Mice

Natural genetic variation between C57BL/6J AND C3H/HeJ affects susceptibility to atherosclerosis and its related risk factors. Recent studies from our laboratory identified a genetic network of co-expressed genes regulating these traits and our mechanistic studies in macrophages identified CD44 as a critical mediator of the network. We found that perturbation of CD44 dramatically affects the network and has possible pleotropic effects on metabolism. CD44 is associated with altered immune function in mice and has been reported to affect atherosclerosis and diabetes, but the underlying mechanism is unclear. Our current hypothesis that CD44 is a critical mediator of a genetic network altering systemic inflammation associated with metabolic syndrome. Thus, we measured the effects of CD44 deficiency in mice challenged with a high fat diet. Male mice (either C57BL6 wild-type or CD44-/-) were fed a diet high in fat, cholesterol, and sucrose for 7 weeks. While there was no significant difference in final body weight, fat mass accumulation was reduced 30% in CD44-/- mice, relative to wild-type mice. Reduced fat mass could not be attributed to reduced food intake or an increase in energy expenditure as measured by indirect calorimetry. However, we observed altered adipose associated inflammation in epidydimal adipose tissue. We found that expression of macrophage markers F4/80, CD11b, and CD14 were decreased 40-60% and inflammation marker TNF-alpha was reduced 40% in CD44-/- mice, relative to wild-type mice. In conclusion, we demonstrate that mice deficient in CD44 exhibit improved metabolic parameters and adiposity, and this may be related to altered adipose tissue inflammation. We are currently extending these studies to include CD44-/- on a C3H/HeJ genetic background to determine if natural variation in macrophage phenotype modulates CD44’s role in adipose tissue associated inflammation.</jats:p

Obesogenic and diabetic effects of CD44 in mice are sexually dimorphic and dependent on genetic background

IntroductionCD44 is a candidate gene for obesity and diabetes development and may be a critical mediator of a systemic inflammation associated with obesity and diabetes.MethodsWe investigated the relationship of CD44 with obesity in CD44-deficient mice challenged with a high-fat diet.ResultsIn mice fed a diet high in fat, cholesterol, and sucrose for 12&nbsp;weeks fat mass accumulation was reduced in CD44-deficient mice bred onto both a C57BL/6J and the naturally TLR deficient C3H/HeJ background. Reduced fat mass could not be attributed to lower food intake or an increase in energy expenditure as measured by indirect calorimetry. However, we observed a 40-60% lower mRNA expression of the inflammation markers, F4/80, CD11b, TNF-α, and CD14, in adipose tissue of CD44-deficient mice on the C57BL/6J background but not the C3H/HeJ background, perhaps indicating that alternative factors may be affecting adiposity in this model. Measures of hepatic steatosis and insulin sensitivity were improved in CD44-deficient mice on a C57BL/6J but not in the C3H/HeJ mice. These results were highly sexually dimorphic as there were no detectable effects of CD44 inactivation in female mice on a C57BL/6&nbsp;J or C3H/HeJ background.ConclusionCD44 was associated with adiposity, liver fat, and glucose in male mice. However, the effects of CD44 on obesity may be independent of TLR4 signaling

Obesogenic and diabetic effects of CD44 in mice are sexually dimorphic and dependent on genetic background

AbstractIntroductionCD44 is a candidate gene for obesity and diabetes development and may be a critical mediator of a systemic inflammation associated with obesity and diabetes.MethodsWe investigated the relationship of CD44 with obesity in CD44-deficient mice challenged with a high-fat diet.ResultsIn mice fed a diet high in fat, cholesterol, and sucrose for 12 weeks fat mass accumulation was reduced in CD44-deficient mice bred onto both a C57BL/6J and the naturally TLR deficient C3H/HeJ background. Reduced fat mass could not be attributed to lower food intake or an increase in energy expenditure as measured by indirect calorimetry. However, we observed a 40–60% lower mRNA expression of the inflammation markers, F4/80, CD11b, TNF-α, and CD14, in adipose tissue of CD44-deficient mice on the C57BL/6J background but not the C3H/HeJ background, perhaps indicating that alternative factors may be affecting adiposity in this model. Measures of hepatic steatosis and insulin sensitivity were improved in CD44-deficient mice on a C57BL/6J but not in the C3H/HeJ mice. These results were highly sexually dimorphic as there were no detectable effects of CD44 inactivation in female mice on a C57BL/6 J or C3H/HeJ background.ConclusionCD44 was associated with adiposity, liver fat, and glucose in male mice. However, the effects of CD44 on obesity may be independent of TLR4 signaling.</jats:sec

Abstract 643: Atherosclerosis Susceptibility in the Collaborative Cross

Objective: The Collaborative Cross (CC) is a large recombinant inbred mouse population, generated from elaborate intercrosses of C57BL6/J, A/J, NOD/ShiLtJ, NZO/HiLtJ, WSB/EiJ, CAST/EiJ, PWK/PhJ, and 129S1/SvImJ mouse strains, useful for complex trait mapping and systems genetics. The CC population has tremendous genetic diversity, containing approximately 45 million segregating single-nucleotide polymorphisms (SNPs). The purpose of this study was to characterize atherosclerosis susceptibility in an initial cohort of Collaborative Cross strains. Methods and Results: We obtained 5 females from 20 CC lines available at the University of North Carolina and placed them on a low-fat, synthetic diet (AIN-76) for 2 weeks. Following two weeks of diet, all mice were assessed for plasma cardio-metabolic risk factors. The mice were then randomly assigned to cages and placed on a synthetic high-fat, cholic acid (HFCA) diet that contained 20% fat, 1.25% cholesterol, and 0.5% cholic acid. Aortic root atherosclerosis and cardio-metabolic risk factors were quantitated following 16 weeks of HFCA diet feeding. Atherosclerotic lesion size ranged from completely resistant (strains C004/TauUnc and CC037/TauUnc) to moderate lesion development in a majority of several strains. Notably all mice from strain CC063/Unc died prior to 20 weeks of age, while strain CC028/GeniUnc was highly susceptible to lesion development with an average lesion size of 105,781 ± 17,370 um 2 . As expected, strain is a significant contributor to atherosclerosis susceptibility (one way Anova analysis, p&lt;8.23x10 -08 ). Similar effects were observed for circulating cholesterol with strains C004/TauUnc and CC037/TauUnc having relatively low circulating total cholesterol after HFCA feeding (187 and 198 mg/dl respectively) to &gt; 500 mg/dl in strains CC006/UNC, CC011/Unc and CC036/Unc. Circulating cholesterol and atherosclerosis were significantly correlated (Spearman rho&gt;0.30, p&lt; 0.007). Conclusion: These results suggest that selective crosses between various CC strains should yield loci associated with atherosclerosis. High-resolution genome-wide association analysis for atherosclerosis may be feasible when more Collaborative Cross strains become available. </jats:p