Göttingen minipig model of diet-induced atherosclerosis: influence of mild streptozotocin-induced diabetes on lesion severity and markers of inflammation evaluated in obese, obese and diabetic, and lean control animals

Abstract

BackgroundFrom a pharmacological perspective, readily-available, well-characterized animal models of cardiovascular disease, including relevant in vivo markers of atherosclerosis are important for evaluation of novel drug candidates. Furthermore, considering the impact of diabetes mellitus on atherosclerosis in human patients, inclusion of this disease aspect in the characterization of a such model, is highly relevant. The objective of this study was to evaluate the effect of mild streptozotocin-induced diabetes on ex- and in vivo end-points in a diet-induced atherosclerotic minipig model.MethodsCastrated male Göttingen minipigs were fed standard chow (CD), atherogenic diet alone (HFD) or with superimposed mild streptozotocin-induced diabetes (HFD-D). Circulating markers of inflammation (C-reactive protein (CRP), oxidized low-density lipoprotein (oxLDL), plasminogen activator inhibitor-1, lipid and glucose metabolism were evaluated together with coronary and aortic atherosclerosis after 22 or 43 diet-weeks. Group differences were evaluated by analysis of variance for parametric data and Kruskal–Wallis test for non-parametric data. For qualitative assessments, Fisher’s exact test was applied. For all analyses, p < 0.05 was considered statistically significant.ResultsOverall, HFD and HFD-D displayed increased CRP, oxLDL and lipid parameters compared to CD at both time points. HFD-D displayed impaired glucose metabolism as compared to HFD and CD. Advanced atherosclerotic lesions were observed in both coronary arteries and aorta of HFD and HFD-D, with more advanced plaque findings in the aorta but without differences in lesion severity or distribution between HFD and HFD-D. Statistically, triglyceride was positively (p = 0.0039), and high-density lipoprotein negatively (p = 0.0461) associated with aortic plaque area.ConclusionsIn this model, advanced coronary and aortic atherosclerosis was observed, with increased levels of inflammatory markers, clinically relevant to atherosclerosis. No effect of mild streptozotocin-induced diabetes was observed on plaque area, lesion severity or inflammatory markers.Electronic supplementary materialThe online version of this article (doi:10.1186/s12967-015-0670-2) contains supplementary material, which is available to authorized users.

Dietary normalization from a fat, fructose and cholesterol-rich diet to chow limits the amount of myocardial collagen in a Göttingen Minipig model of obesity

“…This is in line with porcine studies linking increased myocardial oxidative stress, inflammation and development of myocardial fibrosis [ 27 , 30 ]. In a previous study of obese Göttingen Minipigs levels of oxidized low-density lipoprotein (oxLDL) and C-reactive protein, markers of systemic inflammation, were found to be increased after 22 weeks of a fat, fructose and cholesterol-rich diet [ 26 ]. Dietary fructose has been shown to contribute to inflammation in different tissues [ 36 ] and the dietary content of fructose in the present study may therefore have caused inflammation similar to the study by Ludvigsen and coworkers [ 26 ].…”

“…In a previous study of obese Göttingen Minipigs levels of oxidized low-density lipoprotein (oxLDL) and C-reactive protein, markers of systemic inflammation, were found to be increased after 22 weeks of a fat, fructose and cholesterol-rich diet [ 26 ]. Dietary fructose has been shown to contribute to inflammation in different tissues [ 36 ] and the dietary content of fructose in the present study may therefore have caused inflammation similar to the study by Ludvigsen and coworkers [ 26 ]. Furthermore, increased levels of oxLDL have been directly associated with stimulation of cardiac fibroblast signaling and collagen formation [ 37 ].…”

“…Two different diets with high fat, fructose and cholesterol content were used in the study. 5B4L was used for the first 5 months of the study period [ 26 ], whereas, 9G4U was used for the remainder of the study in order to avoid extremely high plasma cholesterol. Both diets contained 4.1 kcal/g with (percentage by weight) 16.7% protein, 19.8% fats and 42.3% carbohydrate.…”

“…Plasma was stored at − 80 °C until further analysis, except plasma used for glucose analysis which was performed on the day of IVGTT. Intravenous glucose tolerance index (K G ) was calculated as the negative slope of the linear regression of the natural logarithm to glucose vs. time from 5 to 30 min of IVGTT and area under the curve for insulin response was calculated at sampling time 0–60 min (AUC Insulin ), both as previously described [ 26 , 31 ]. Blood samples for evaluation of plasma triglyceride and total cholesterol levels were obtained 2-3 days prior to IVGTT, and handled as described above.…”

“…High-performance liquid chromatography using Superose 6 columns (10/300, GE Healthcare, Brøndby, DK) in an automatized system (Agilent 1100 HPLC system, Agilent Technologies, Waldbronn, GE) was used to estimate group cholesterol fractions; high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), very-low-density lipoprotein cholesterol (VLDL-C). Pooled plasma samples from termination were used and handled as previously described [ 26 ]. In short, two to three animals with total plasma cholesterol concentrations close to the group mean were selected (SD n = 2, FFC n = 3 and FFC/SD n = 3).…”