High-fat/high-sucrose diet-induced obesity results in joint-specific development of osteoarthritis-like degeneration in a rat model

Abstract

Objectives: Metabolic syndrome and low-grade systemic inflammation are associated with knee osteoarthritis (OA), but the relationships between these factors and OA in other synovial joints are unclear. The aim of this study was to determine if a high-fat/high-sucrose (HFS) diet results in OA-like joint damage in the shoulders, knees, and hips of rats after induction of obesity, and to identify potential joint-specific risks for OA-like changes.

Methods: A total of 16 male Sprague-Dawley rats were allocated to either the diet-induced obesity group (DIO, 40% fat, 45% sucrose, n = 9) or a chow control diet (n = 7) for 12 weeks. At sacrifice, histological assessments of the shoulder, hip, and knee joints were performed. Serum inflammatory mediators and body composition were also evaluated. The total Mankin score for each animal was assessed by adding together the individual Modified Mankin scores across all three joints. Linear regression modelling was conducted to evaluate predictive relationships between serum mediators and total joint damage.

Results: The HFS diet, in the absence of trauma, resulted in increased joint damage in the shoulder and knee joints of rats. Hip joint damage, however, was not significantly affected by DIO, consistent with findings in human studies. The total Mankin score was increased in DIO animals compared with the chow group, and was associated with percentage of body fat. Positive significant predictive relationships for total Mankin score were found between body fat and two serum mediators (interleukin 1 alpha (IL-1α) and vascular endothelial growth factor (VEGF)).

Conclusion: Systemic inflammatory alterations from DIO in this model system may result in a higher risk for development of knee, shoulder, and multi-joint damage with a HFS diet.Cite this article: K. H. Collins, D. A. Hart, R. A. Seerattan, R. A. Reimer, W. Herzog. High-fat/high-sucrose diet-induced obesity results in joint-specific development of osteoarthritis-like degeneration in a rat model. Bone Joint Res 2018;7:274-281. DOI: 10.1302/2046-3758.74.BJR-2017-0201.R2.

Keywords: Hip; Inflammation; Knee; Shoulder; Sprague-Dawley.

Fig. 1

Graph showing that diet-induced obesity (DIO) leads to increases in the severity of joint damage in the shoulders, knees, and hips of rats. DIO animals (n = 9) had increased Modified Mankin scores at the shoulder and knee compared with chow-fed animals (n = 7). Overlapping scores are represented by one point on the graph. Each line indicates the scores for one animal across the three joints. Hip scores were similar between groups. The blue line corresponds with the DIO animal depicted in Figure 2 for shoulder and hip, the purple line corresponds with the DIO animal depicted in Figure 2 for knee, and the green line corresponds with the chow animal illustrated in Figure 2. *p ⩽ 0.05 between DIO versus chow for shoulder and knee joints.

Fig. 2

Histology images taken at ×10, showing that DIO leads to increases in joint damage in shoulder and knee joints, but not hip joints. Scale bars indicate 500 μm. Black arrows indicate lesions.

Graphs showing that: a) total Mankin score is increased in diet-induced obesity (DIO) animals versus chow-fed controls; b) the sum of knee and shoulder Mankin scores is increased in DIO animals versus chow-fed controls; c) total Mankin score is positively significantly associated with percentage of body fat across all animals; and d) the sum of knee and shoulder Mankin scores is positively significantly associated with percentage of body fat across all animals. Empty squares represent DIO animals (n = 9) and black squares represent chow-fed control animals (n = 7). *p ⩽ 0.05 in DIO versus chow.