Oligonucleotide Microarray Analysis of Dietary-Induced Hyperlipidemia Gene Expression Profiles in Miniature Pigs

BACKGROUND: Hyperlipidemia animal models have been established, but complete gene expression profiles of the transition from normal lipid levels have not been obtained. Miniature pigs are useful model animals for gene expression studies on dietary-induced hyperlipidemia because they have a similar anatomy and digestive physiology to humans, and blood samples can be obtained from them repeatedly. METHODOLOGY: Two typical dietary treatments were used for dietary-induced hyperlipidemia models, by using specific pathogen-free (SPF) Clawn miniature pigs. One was a high-fat and high-cholesterol diet (HFCD) and the other was a high-fat, high-cholesterol, and high-sucrose diet (HFCSD). Microarray analyses were conducted from whole blood samples during the dietary period and from white blood cells at the end of the dietary period to evaluate the transition of expression profiles of the two dietary models. PRINCIPAL FINDINGS: Variations in whole blood gene expression intensity within the HFCD or the HFCSD group were in the same range as the controls provide with normal diet at all periods. This indicates uniformity of dietary-induced hyperlipidemia for our dietary protocols. Gene ontology- (GO) based functional analyses revealed that characteristics of the common changes between HFCD and HFCSD were involved in inflammatory responses and reproduction. The correlation coefficient between whole blood and white blood cell expression profiles at 27 weeks with the HFCSD diet was significantly lower than that of the control and HFCD diet groups. This may be due to the effects of RNA originating from the tissues and/or organs. CONCLUSIONS: No statistically significant differences in fasting plasma lipids and glucose levels between the HFCD and HFCSD groups were observed. However, blood RNA analyses revealed different characteristics corresponding to the dietary protocols. In this study, whole blood RNA analyses proved to be a useful tool to evaluate transitions in dietary-induced hyperlipidemia gene expression profiles in miniature pigs

The relation of tissue or organ ESTs to the white blood cell contribution indicator.

<p>The X-axis indicates the expression intensity ratio of white blood cells to whole blood for each gene as the white blood cell contribution indicator in our experiments. The Y-axis indicates the liver, adipose tissue, or muscle EST numbers normalized to the blood EST number of each gene in Unigene, an NCBI database of the transcriptome.</p

Summary of dietary-related correlation coefficients among different diet groups.

<p>(A) Whole blood after 10 weeks. (B) Whole blood after 19 weeks. (C) Whole blood after 27 weeks. (D) White blood cells after 27 weeks. The bottom and top of the boxes represent the 25th and 75th percentiles respectively. The lower and upper whiskers denote the minimum and maximum values of the data. Comparisons of the groups were made with the ANOVA test. NS; not significant.</p

Subject body weights.

<p><b>•</b> represents control, <b>⧫</b> represents HFCD, and ▴ represents HFCSD. Values correspond to means (SD).</p

Functional classes of up- or down-regulated genes between HFCD and control.

<p>GO MF; GO molecular function, GO BP; GO biological process, Kegg; Kegg pathway.</p

The ratio of basophils to white blood cells (%).

<p>Values are the mean ± SD. NS; not significant.</p>†<p><i>P</i> values were calculated using a one-way factorial ANOVA.</p

Fasting plasma triglyceride levels (mg/dL).

<p>Values are mean ± SD. NS; not significant.</p>†<p><i>P</i> values were calculated using a one-way factorial ANOVA.</p

Top 10 significantly up-regulated genes in HFCSD.

<p>Top 10 significantly up-regulated genes in HFCSD.</p

Fasting plasma LDL cholesterol levels (mg/dL).

<p>Values are mean ± SD. NS; not significant.</p>†<p><i>P</i> values were calculated using a one-way factorial ANOVA.</p

Predominant GO terms for which the ratio changed in HFCD.

<p>Values are mean ± SD.</p