Emily C. Graff

Niacin Increases Adiponectin and Decreases Adipose Tissue Inflammation in High Fat Diet-Fed Mice

Aims To determine the effects of niacin on adiponectin and markers of adipose tissue inflammation in a mouse model of obesity. Materials and Methods Male C57BL/6 mice were placed on a control or high-fat diet (HFD) and were maintained on such diets for the duration of the study. After 6 weeks on the control or high fat diets, vehicle or niacin treatments were initiated and maintained for 5 weeks. Identical studies were conducted concurrently in HCA2 −/− (niacin receptor−/−) mice. Results Niacin increased serum concentrations of the anti-inflammatory adipokine, adiponectin by 21% in HFD-fed wild-type mice, but had no effect on lean wild-type or lean or HFD-fed HCA2 −/− mice. Niacin increased adiponectin gene and protein expression in the HFD-fed wild-type mice only. The increases in adiponectin serum concentrations, gene and protein expression occurred independently of changes in expression of PPARγ C/EBPα or SREBP-1c (key transcription factors known to positively regulate adiponectin gene transcription) in the adipose tissue. Further, niacin had no effect on adipose tissue expression of ERp44, Ero1-Lα, or DsbA-L (key ER chaperones involved in adiponectin production and secretion). However, niacin treatment attenuated HFD-induced increases in adipose tissue gene expression of MCP-1 and IL-1β in the wild-type HFD-fed mice. Niacin also reduced the expression of the pro-inflammatory M1 macrophage marker CD11c in HFD-fed wild-type mice. Conclusions Niacin treatment attenuates obesity-induced adipose tissue inflammation through increased adiponectin and anti-inflammatory cytokine expression and reduced pro-inflammatory cytokine expression in a niacin receptor-dependent manner.

Metabolic phenotype and adipose and liver features in a high-fat Western diet-induced mouse model of obesity-linked NAFLD

nonalcoholic fatty liver disease (NAFLD), an obesity and insulin resistance associated clinical condition - ranges from simple steatosis to nonalcoholic steatohepatitis. To model the human condition, a high-fat Western diet that includes liquid sugar consumption has been used in mice. Even though liver pathophysiology has been well characterized in the model, little is known about the metabolic phenotype (e.g., energy expenditure, activity, or food intake). Furthermore, whether the consumption of liquid sugar exacerbates the development of glucose intolerance, insulin resistance, and adipose tissue dysfunction in the model is currently in question. In our study, a high-fat Western diet (HFWD) with liquid sugar [fructose and sucrose (F/S)] induced acute hyperphagia above that observed in HFWD-fed mice, yet without changes in energy expenditure. Liquid sugar (F/S) exacerbated HFWD-induced glucose intolerance and insulin resistance and impaired the storage capacity of epididymal white adipose tissue (eWAT). Hepatic TG, plasma alanine aminotransferase, and normalized liver weight were significantly increased only in HFWD+F/S-fed mice. HFWD+F/S also resulted in increased hepatic fibrosis and elevated collagen 1a2, collagen 3a1, and TGFβ gene expression. Furthermore, HWFD+F/S-fed mice developed more profound eWAT inflammation characterized by adipocyte hypertrophy, macrophage infiltration, a dramatic increase in crown-like structures, and upregulated proinflammatory gene expression. An early hypoxia response in the eWAT led to reduced vascularization and increased fibrosis gene expression in the HFWD+F/S-fed mice. Our results demonstrate that sugary water consumption induces acute hyperphagia, limits adipose tissue expansion, and exacerbates glucose intolerance and insulin resistance, which are associated with NAFLD progression.

Anti-inflammatory effects of the hydroxycarboxylic acid receptor 2.

The hydroxycarboxylic acid receptors (HCA1-3) are a family of G-protein-coupled receptors that are critical for sensing endogenous intermediates of metabolism. All three receptors are predominantly expressed on adipocytes and mediate anti-lipolytic effects. In addition to adipocytes, HCA2 is highly expressed on immune cells, including macrophages, monocytes, neutrophils and dermal dendritic cells, among other cell types. The endogenous ligand for HCA2 is beta-hydroxybutyrate (β-OHB), a ketone body produced by the liver through β-oxidation when an individual is in a negative energy balance. Recent studies demonstrate that HCA2 mediates profound anti-inflammatory effects in a variety of tissues, indicating that HCA2 may be an important therapeutic target for treating inflammatory disease processes. This review summarizes the roles of HCA2 on inflammation in a number of tissues and clinical states.

Characterization of HOX gene expression in canine mammary tumour cell lines from spontaneous tumours

Spatial/temporal controls of development are regulated by the homeotic (HOX) gene complex and require integration with oncogenes and tumour suppressors regulating cell cycle exit. Spontaneously derived neoplastic canine mammary carcinoma cell models were investigated to determine if HOX expression profiles were associated with neoplasia as HOX genes promote neoplastic potential in human cancers. Comparative assessment of human and canine breast cancer expression profiles revealed remarkable similarity for all four paralogous HOX gene clusters and several unlinked HOX genes. Five canine HOX genes were overexpressed with expression profiles consistent with oncogene-like character (HOXA1, HOXA13, HOXD4, HOXD9 and SIX1) and three HOX genes with underexpressed profiles (HOXA11, HOXC8 and HOXC9) were also identified as was an apparent nonsense mutation in HOXC6. This data, as well as a comparative analysis of similar data from human breast cancers suggested expression of selected HOX genes in canine mammary carcinoma could be contributing to the neoplastic phenotype.

Restricted feeding for 9 h in the active period partially abrogates the detrimental metabolic effects of a Western diet with liquid sugar consumption in mice

BACKGROUND Obesity is a major public health concern that can result from diets high in fat and sugar, including sugar sweetened beverages. A proposed treatment for dietary-induced obesity is time-restricted feeding (TRF), which restricts consumption of food to specific times of the 24-hour cycle. Although TRF shows great promise to prevent obesity and the development of chronic disease, the effects of TRF to reverse metabolic changes and the development of NAFLD in animal models of a Western diet with sugary water consumption is not known. OBJECTIVE The objective of the current study was to evaluate the role of TRF in the treatment of obesity and NAFLD through examination of changes in metabolic and histopathologic parameters. METHODS To better understand the role of TRF in the treatment of obesity and NAFLD, we investigated the metabolic phenotype and NAFLD parameters in a mouse model of NAFLD in which obesity and liver steatosis are induced by a Western Diet (WD): a high-fat diet of lard, milkfat and Crisco with sugary drinking water. Mice were subjected to a short-term (4-weeks) and long-term (10-weeks) TRF in which food was restricted to 9h at night. RESULTS Prior to TRF treatment, the WD mice had increased body mass, and exhibited less activity, and higher average daytime energy expenditure (EE) than chow fed mice. Approximately 4- and 10-weeks following TFR treatment, WD-TRF had moderate but not statistically significant weight loss compared to WD-ad libitum (WD-AL) mice. There was a modest but significant reduction in the inguinal adipose tissue weight in both WD-TRF groups compared to the WD-AL groups; however, there was no difference in epididymal and retroperitoneal adipose tissue mass or adipocyte size distribution. In contrast, the diet-induced increase in normalized liver tissue weight, hepatic triglyceride, and NAFLD score was partially abrogated in the 4-week WD-TRF mice, while systemic insulin resistance was partially abrogated and glucose intolerance was completely abrogated in the 10-week WD-TRF mice. Importantly, WD-induced metabolic dysfunction (substrate utilization, energy expenditure, and activity) was partially abrogated by 4- and 10-week TRF. CONCLUSIONS Our results support the hypothesis that TRF aids in reducing the detrimental metabolic effects of consuming a WD with sugary drinking water but does not ameliorate obesity.

Engraftment of canine peripheral blood lymphocytes into nonobese diabetic-severe combined immune deficient IL-2R common gamma chain null mice.

To study the canine immune system we generated a mouse model engrafted with canine lymphocytes using NOD SCID IL2R common gamma chain -/- (NSG) mice as recipients (Ca-PBL-SCID). Engraftment of canine peripheral blood lymphocytes (PBLs) was determined post-injection with 10(7) peripheral blood mononuclear cells (PBMCs) into irradiated NSG mice using flow cytometry and fluorescently labeled antibodies specific to canine helper T cells (CD45(+) CD4(+)), cytotoxic lymphocytes (CD45(+) CD8(+)), regulatory T cells (CD45(+) CD4(+) Foxp3(+)), and B cells (CD45(+) Ig(+) CD21lo). Canine CD45(+) lymphocytes were detectable as early as day 1 in the peritoneal cavity, and beginning at 9 days in the blood, bone marrow, and spleen. CD4(+) T cells, of which Foxp-3(+) CD25hi cells constituted a minor percentage, were the predominant lymphocyte population at 9 days post engraftment contrasting with increasing proportions of CD8(+) CTLs and Ig(+) B cells beginning at 16 days. Canine immunoglobulin was initially detected in the serum of Ca-PBL-SCID mice at 9 days post-engraftment and peaked in concentration at day 36. From day 28 to 52 post-engraftment 30% of the Ca-PBL-SCID mice became markedly anemic and thrombocytopenic, yet gross and histopathologic examination of bone marrow, kidneys, spleen, liver, and intestine revealed no obvious lesions. Blood smear evaluation revealed agglutination of mature red blood cells, reticulocytes and a regenerative anemia. These findings demonstrate that NSG mice are capable of engraftment of canine PBLs yet develop graft versus host disease similar to Hu-PBL-SCID mice.

Hypercalcemia of malignancy associated with renal cell carcinoma in a dog.

A 10 yr old castrated male Siberian husky was evaluated for polyuria, polydipsia, a retroperitoneal mass, and urolithiasis. A marked elevation in Ca was noted on initial blood work, and results of additional testing were consistent with hypercalcemia of malignancy, including an elevated parathyroid hormone-related peptide (PTHrp) value. Based on clinical signs, blood work, diagnostic imaging, and cytology results, unilateral renal neoplasia was suspected. Following a complete right nephrectomy and cystotomy, histopathologic examination confirmed a diagnosis of renal cell carcinoma (RCC). Five days postoperatively, the hypercalcemia had nearly resolved and the PTHrp was zero. This is the first reported case of hypercalcemia of malignancy associated with RCC in a dog.

Comparison of Chemiluminescence vs. Infrared Techniques for Detection of Fetuin-A in Saliva.

The western blotting technique for transfer and detection of proteins, named following the discovery of southern and northern blotting for DNA- and RNA-blotting, respectively, has traditionally relied on the use of X-ray films to capture chemiluminescence. Recent advancements use super-cooled charge coupled devices (CCD) cameras to capture both chemiluminescence and fluorescence images, which exhibit a greater dynamic range compared to traditional X-ray film. Chemiluminescence detected by a CCD camera records photons and displays an image based on the amount of light generated as a result of a dynamic chemical reaction. Fluorescent detection with a CCD camera, on the other hand, is measured in a static state. Despite this advantage, researchers continue to widely use chemiluminescent detection methods due to the generally poor performance of fluorophores in the visible spectrum. Infrared imaging systems offer a solution to the dynamic reactions of chemiluminescence and the poor performance of fluorophores detected in the visible spectrum, by imaging fluorophores in the infrared spectrum. Infrared imaging is static, has a wide linear range, high sensitivity, and reduced autofluorescence and light scatter. A distinct advantage of infrared imaging is the ability to detect two target proteins simultaneously on the same blot which increases accuracy of quantification and comparison, while minimizing the need for stripping and reprobing. Here, we compare the methodology for chemiluminescent (UVP BioChemi) and infrared (UVP Odyssey) detection of salivary total and phosphorylated fetuin-A, a multifunctional protein associated with cardio-metabolic risk, and discuss the advantages and disadvantages of these methodologies.