Dietary Aloe Improves Insulin Sensitivity via the Suppression of Obesity-induced Inflammation in Obese Mice

Abstract

Background: Insulin resistance is an integral feature of metabolic syndromes, including obesity, hyperglycemia, and hyperlipidemia. In this study, we evaluated whether the aloe component could reduce obesity-induced inflammation and the occurrence of metabolic disorders such as blood glucose and insulin resistance.

Methods: Male C57BL/6 obese mice fed a high-fat diet for 54 days received a supplement of aloe formula (PAG, ALS, Aloe QDM, and Aloe QDM complex) or pioglitazone (PGZ) and were compared with unsupplemented controls (high-fat diet; HFD) or mice fed a regular diet (RD). RT-PCR and western blot analysis were used to quantify the expression of obesity-induced inflammation.

Results: Aloe QDM lowered fasting blood glucose and plasma insulin compared with HFD. Obesity-induced inflammatory cytokine (IL-1β, -6, -12, TNF-α) and chemokine (CX3CL1, CCL5) mRNA and protein were decreased markedly, as was macrophage infiltration and hepatic triglycerides by Aloe QDM. At the same time, Aloe QDM decreased the mRNA and protein of PPARγ/LXRα and 11β-HSD1 both in the liver and WAT.

Conclusion: Dietary aloe formula reduces obesity-induced glucose tolerance not only by suppressing inflammatory responses but also by inducing anti-inflammatory cytokines in the WAT and liver, both of which are important peripheral tissues affecting insulin resistance. The effect of Aloe QDM complex in the WAT and liver are related to its dual action on PPARγ and 11β-HSD1 expression and its use as a nutritional intervention against T2D and obesity-related inflammation is suggested.

Keywords: Aloe QDM complex; Insulin sensitivity; Obesity-induced inflammation; Type 2 diabetes mellitus.

Figure 1

Effects of aloe formulas on body weight change and obesity-induced glucose intolerance. C57BL/6 mice were fed a high-fat diet supplemented with an aloe formula. (A) Weekly changes in body weight of aloe formula-supplemented mice. (B) fasting glucose and (C) insulin levels in plasma. Data are means±SEM.values. ^‡p<0.01 compared with RD-fed mice. ^*p<0.05, ^†p<0.01 compared with untreated HFD-fed mice.

Figure 2

Histological observations of liver and WAT. At the end of the experimental period, (A) fatty livers were isolated from representative mice from each group, sectioned, and then stained with hematoxylin and eosin. Photomicrographs are of tissues isolated from RD-fed mice (a), untreated HFD mice (b), PGZ (c), PAG (d), ALS (e), Aloe QDM (f), and Aloe QDM complex-treated HFD mice (g). Photomicrographs were taken at a magnification of ×200. (B) epididymal fat pads were isolated from mice, sectioned, and then stained with hematoxylin and eosin. Photomicrographs are of tissues isolated from RD-fed mice (a), untreated HFD mice (b), PGZ (c), and Aloe QDM complex-treated HFD mice (d). Arrows show infiltrated cells. Photomicrographs were taken at a magnification of ×400.

Figure 3

Effect of aloe formulas on obesity-induced inflammation. Liver and WAT were isolated from mice. (A) mRNA expression in the both liver and WAT were measured by RT-PCR. (B) protein expression of inflammatory cytokine-related enzymes and (C) proinflammatory cytokines and chemokines were measured by western blot. This was repeated in triplicate and similar results were obtained in all three.

Figure 4

Effect of aloe formulas on adipogenesis. Liver and WAT were isolated from mice. (A) mRNA expression of PPARγ and LXRα in the both liver and WAT were measured by RT-PCR. (B) protein expression of ABCA1 was measured by western blot. (C) mRNA expression and (D) protein expression of 11β-HSD1 in both the liver and WAT were measured by RT-PCR and western blot, respectively. This was repeated in triplicate and similar results were obtained in all three.

Figure 5

Effects of aloe formulas on antiinflammatory cytokines. WAT were isolated from mice. Protein expressions of antiinflammatory cytokines were measured by western blot. This was repeated in triplicate and similar results were obtained in all three.