The Response of Hepatic Transcriptome to Dietary Cholesterol in Prague Hereditary Hypercholesterolemic (PHHC) Rat

Prebiotic and Immunomodulatory Properties of the Microalga Chlorella vulgaris and Its Synergistic Triglyceride-Lowering Effect with Bifidobacteria

The microalga Chlorella and strains of Bifidobacterium have been used in human or animal food supplements for decades because of their positive health effects. The presented study assessed different properties of C. vulgaris and its combination with bifidobacteria with the aim to develop new functional foods. The growth of four bifidobacteria strains in milk and whey supplemented with 1.0% (w/v) C. vulgaris and the immunomodulatory effects of aqueous Chlorella solutions (0.5%, 1.0%, and 3.0%) on human peripheral mononuclear cells were evaluated. Furthermore, synergistic effects on lipid metabolism of rats fed a high-fat diet with Chlorella and B. animalis subsp. lactis BB-12® were analysed. Chlorella had a positive growth-promoting effect on the tested bifidobacteria (p < 0.05), and significantly increased the secretion of inflammatory cytokines (tumor necrosis factor-α, interleukin-10, and interleukin-6), depending on the concentration of Chlorella (p < 0.05). After 8 weeks, significant synergistic effects of Chlorella and bifidobacteria on triglyceride levels in rat heart, liver, and serum were observed (p < 0.05). These results demonstrate that various combinations of Chlorella and bifidobacteria have significant potential for the development of new fermented products, dependent on the algal species, probiotic strain, application form, and concentrations for acceptable sensory quality for consumers.

Functional Properties of Chlorella vulgaris, Colostrum, and Bifidobacteria, and Their Potential for Application in Functional Foods

The market for new functional foods and food supplements is rapidly evolving, with a current emphasis on using natural sources. Algae, probiotics, and colostrum are rich sources of nutrients and bioactive compounds with positive effects on human and animal health. To determine the potential for developing new functional foods combining these components, we evaluated their synergistic effects. We assessed the growth of selected bifidobacteria in a medium supplemented with Chlorella vulgaris and its immunomodulatory and cytotoxic effects on the human peripheral mononuclear cells and colon cancer cell lines Caco-2 and HT29. The hypocholesterolemic effects of Chlorella powder and bovine colostrum fermented by Bifidobacterium animalis subsp. lactis BB12® on lipid metabolism in rats fed a high-fat diet were also determined. Chlorella addition promoted Bifidobacteria growth, with significantly increased inflammatory cytokine (TNF-α and IL-6) levels following 1.0% (w/v) Chlorella stimulation. Rats fed diets containing fermented colostrum with 0.5% (w/v) added Chlorella powder exhibited significantly decreased triglyceride, very low-density lipoprotein, and alanine and aspartate aminotransferase levels, compared to those of the control group. These results support that C. vulgaris is not cytotoxic in intestinal cell models and affords prebiotic and immunomodulatory effects, as well as synergistic triglyceride-lowering effects with bovine colostrum and B. animalis subsp. lactis BB-12.

Reverse Transport of Cholesterol Is the Reason for Resistance to Development of Atherosclerosis in Prague Hereditary Hypercholesterolemic (PHHC) Rat

The Prague Hereditary Hypercholesterolemic (PHHC) rat is a model of hypercholesterolemia. In previous experiments, it was found to be completely resistant to the development of atherosclerosis. It was assumed that the reverse transport of cholesterol (RCT) might be the reason for this resistance. In this study, RCT was measured in vivo by cholesterol efflux from macrophages to plasma, using previously established methods for RCT in mice (Rader 2003), optimized for measurements in rats. Primary cell culture of macrophages was labeled with 14C-cholesterol and then injected intraperitoneally into rats. Plasma and feces were collected at 24 and 48 h. The plasma 14C-cholesterol levels at both 24 and 48 h were significantly higher in male PHHC rats compared to control Wistar rats. The PHHC rats excreted less 14C-cholesterol in feces in 24 and 48 h compared to Wistar rats. The largest pool of 14C-cholesterol was found in the adipose tissue of PHHC rats and in contrast lower levels of 14C-cholesterol were measured in the liver and muscle tissues of PHHC rats compared with Wistar rats. Increasing release of 14C-cholesterol efflux from macrophages demonstrates accelerated RTC and leads to prevention of atherogenesis in PHHC rats.