Sensing of Dietary Lipids by Enterocytes: A New Role for SR-BI/CLA-1

BACKGROUND: The intestine is responsible for absorbing dietary lipids and delivering them to the organism as triglyceride-rich lipoproteins (TRL). It is important to determine how this process is regulated in enterocytes, the absorptive cells of the intestine, as prolonged postprandial hypertriglyceridemia is a known risk factor for atherosclerosis. During the postprandial period, dietary lipids, mostly triglycerides (TG) hydrolyzed by pancreatic enzymes, are combined with bile products and reach the apical membrane of enterocytes as postprandial micelles (PPM). Our aim was to determine whether these micelles induce, in enterocytes, specific early cell signaling events that could control the processes leading to TRL secretion. METHODOLOGY/PRINCIPAL FINDINGS: The effects of supplying PPM to the apex of Caco-2/TC7 enterocytes were analyzed. Micelles devoid of TG hydrolysis products, like those present in the intestinal lumen in the interprandial period, were used as controls. The apical delivery of PPM specifically induced a number of cellular events that are not induced by interprandial micelles. These early events included the trafficking of apolipoprotein B, a structural component of TRL, from apical towards secretory domains, and the rapid, dose-dependent activation of ERK and p38MAPK. PPM supply induced the scavenger receptor SR-BI/CLA-1 to cluster at the apical brush border membrane and to move from non-raft to raft domains. Competition, inhibition or knockdown of SR-BI/CLA-1 impaired the PPM-dependent apoB trafficking and ERK activation. CONCLUSIONS/SIGNIFICANCE: These results are the first evidence that enterocytes specifically sense postprandial dietary lipid-containing micelles. SR-BI/CLA-1 is involved in this process and could be a target for further study with a view to modifying intestinal TRL secretion early in the control pathway

Health claims assessment in the field of joint and cartilage: a consensus viewpoint of the Group for the Respect of Ethics and Excellence in Science

Abstract Introduction: In 2006, the European Parliament and Council issued a regulation (No. 1924/2006) for the nutrition and health claims made on foods, including food supplements. According to the regulation, the use of nutrition and health claims shall only be permitted if the substance in respect of which the claim is made has been shown to have a beneficial nutritional or physiological effect. In the field of joint and cartilage health, there is no clear scientific-based definition of the nature of such a beneficial nutritional or physiological effect. The objective of this paper is to scientifically define the possible content of health claims related to joint and cartilage health and to provide scientific guidelines for the design of clinical studies which need to be adopted to substantiate such health claims. Methods: Literature review up to September 2011 followed by a consensus expert discussion organized by the Group for the Respect of Ethics and Excellence in Science (GREES). Results: In line with the general principles of the PASSCLAIM and the Codex recommendations, the GREES identified four acceptable health claims related to joint and cartilage health based on the effects on discomfort, joint and cartilage structural integrity or risk factors for joint and cartilage diseases. The GREES considers that randomized controlled trials on a relevant outcome is the best design to assess health claims. Moreover, animal studies could also be of interest to substantiate some health claims, to assess the clinical relevance of endpoints used in human studies or to extrapolate data obtained in patients to the target (apparently) healthy population. Conclusion: According to the methodology and biomarkers used in the study and whether or not additional animal studies are provided to support the claim, various health claims can be acceptable in the field of joint and cartilage health