Cholesterol-induced inflammation and macrophage accumulation in adipose tissue is reduced by a low carbohydrate diet in guinea pigs

BACKGROUND/OBJECTIVES: The main objective of this study was to evaluate the effects of a high cholesterol (HC) dietary challenge on cholesterol tissue accumulation, inflammation, adipocyte differentiation, and macrophage infiltration in guinea pigs. A second objective was to assess whether macronutrient manipulation would reverse these metabolic alterations. MATERIALS/METHODS: Male Hartley guinea pigs (10/group) were assigned to either low cholesterol (LC) (0.04g/100g) or high cholesterol (HC) (0.25g/100g) diets for six weeks. For the second experiment, 20 guinea pigs were fed the HC diet for six weeks and then assigned to either a low carbohydrate (CHO) diet (L-CHO) (10% energy from CHO) or a high CHO diet (H-CHO) (54% CHO) for an additional six weeks. RESULTS: Higher concentrations of total (P < 0.005) and free (P < 0.05) cholesterol were observed in both adipose tissue and aortas of guinea pigs fed the HC compared to those in the LC group. In addition, higher concentrations of pro-inflammatory cytokines in the adipose tissue (P < 0.005) and lower concentrations of anti-inflammatory interleukin (IL)-10 were observed in the HC group (P < 0.05) compared to the LC group. Of particular interest, adipocytes in the HC group were smaller in size (P < 0.05) and showed increased macrophage infiltration compared to the LC group. When compared to the H-CHO group, lower concentrations of cholesterol in both adipose and aortas as well as lower concentrations of inflammatory cytokines in adipose tissue were observed in the L-CHO group (P < 0.05). In addition, guinea pigs fed the L-CHO exhibited larger adipose cells and lower macrophage infiltration compared to the H-CHO group. CONCLUSIONS: The results of this study strongly suggest that HC induces metabolic dysregulation associated with inflammation in adipose tissue and that L-CHO is more effective than H-CHO in attenuating these detrimental effects.

Erratum: Lutein decreases oxidative stress and inflammation in liver and eyes of guinea pigs fed a hypercholesterolemic diet

This article was initially published on Nutrition Research and Practice with mistyped concentration of lutein used in the study.

Lutein decreases oxidative stress and inflammation in liver and eyes of guinea pigs fed a hypercholesterolemic diet

Guinea pigs were fed a hypercholesterolemic diet (0.25 g/100 g cholesterol) and randomly allocated either to a Control group (n = 9) or to a Lutein (0.1 g/100 g) group (n = 10) for 12 weeks to evaluate oxidative stress and inflammation in both liver and eyes. Malondialdehyde (MDA) concentrations and inflammatory cytokines were measured as well as hepatic nuclear factor-kappaB (NF-kappaB) binding. Lutein concentrations were greater in eyes (P < 0.01) and liver (P < 0.001) in the Lutein group. All guinea pigs had high concentrations of hepatic cholesterol as well as high plasma ALT and AST levels indicative of liver injury. However, the Lutein group had 43% lower hepatic free cholesterol than the Controls (P < 0.05). Hepatic MDA and MDA in the eye were lower in the Lutein compared to the Control group (P < 0.05). Hepatic tumor necrosis factor-alpha was 32% lower in the Lutein group (P < 0.05). Lastly, the Lutein group presented lower NF-kappaB DNA binding activity than the Control group (P < 0.001). These results suggest that in the presence of high cholesterol, lutein exerts both antioxidant and anti-inflammatory effects, which can be explained by attenuated NF-kappaB DNA binding activity. Furthermore, results also suggest that lutein accumulates in the eyes of guinea pigs to protect against oxidative stress.

Effects of resistance training on the inflammatory response

Resistance training (RT) is associated with reduced risk of low grade inflammation related diseases, such as cardiovascular disease and type 2 diabetes. The majority of the data studying cytokines and exercise comes from endurance exercise. In contrast, evidence establishing a relationship between RT and inflammation is more limited. This review focuses on the cytokine responses both following an acute bout, and after chronic RT. In addition, the effect of RT on low grade systemic inflammation such as individuals at risk for type 2 diabetes is reviewed. Cytokines are secreted proteins that influence the survival, proliferation, and differentiation of immune cells and other organ systems. Cytokines function as intracellular signals and almost all cells in the body either secrete them or have cytokine receptors. Thus, understanding cytokine role in a specific physiological situation such as a bout of RT can be exceedingly complex. The overall effect of long term RT appears to ameliorate inflammation, but the specific effects on the inflammatory cytokine, tumor necrosis factor alpha are not clear, requiring further research. Furthermore, it is critical to differentiate between chronically and acute Interleukin-6 levels and its sources. The intensity of the RT and the characteristics of the training protocol may exert singular cytokine responses and as a result different adaptations to exercise. More research is needed in the area of RT in healthy populations, specifically sorting out gender and age RT acute responses. More importantly, studies are needed in obese individuals who are at high risk of developing low grade systemic inflammatory related diseases. Assuring adherence to the RT program is essential to get the benefits after overcoming the first acute RT responses. Hence RT could be an effective way to prevent, and delay low grade systemic inflammatory related diseases.

Low HDL cholesterol is associated with increased atherogenic lipoproteins and insulin resistance in women classified with metabolic syndrome

Both metabolic syndrome (MetS) and elevated LDL cholesterol (LDL-C) increase the risk for cardiovascular disease (CVD). We hypothesized that low HDL cholesterol (HDL-C) would further increase CVD risk in women having both conditions. To assess this, we recruited 89 women with MetS (25-72 y) and LDL-C > or = 2.6 mmol/L. To determine whether plasma HDL-C concentrations were associated with dietary components, circulating atherogenic particles, and other risk factors for CVD, we divided the subjects into two groups: high HDL-C (H-HDL) (> or = 1.3 mmol/L, n = 32) and low HDL-C (L-HDL) (< 1.3 mmol/L, n = 57). Plasma lipids, insulin, adiponectin, apolipoproteins, oxidized LDL, Lipoprotein(a), and lipoprotein size and subfractions were measured, and 3-d dietary records were used to assess macronutrient intake. Women with L-HDL had higher sugar intake and glycemic load (P < 0.05), higher plasma insulin (P < 0.01), lower adiponectin (P < 0.05), and higher numbers of atherogenic lipoproteins such as large VLDL (P < 0.01) and small LDL (P < 0.001) than the H-HDL group. Women with L-HDL also had larger VLDL and both smaller LDL and HDL particle diameters (P < 0.001). HDL-C was positively correlated with LDL size (r = 0.691, P < 0.0001) and HDL size (r = 0.606, P < 0.001), and inversely correlated with VLDL size (r = -0.327, P < 0.01). We concluded that L-HDL could be used as a marker for increased numbers of circulating atherogenic lipoproteins as well as increased insulin resistance in women who are already at risk for CVD.