In patients with diabetes, obesity, or cardiovascular disease, the circulating proinflammatory mediators are often elevated. We made the novel observation that intestinal mucosal mast cells (MMC) are activated by fat absorption. In our well established conscious lymph fistula rats, we showed that fat absorption activates the intestinal mucosal mast cells (MMC) and they degranulate as evidenced by the marked increase (~ 20 fold) of the MMC marker protease II in intestinal lymph relative to fasting lymph (pre-ingestion of fat). This observation is very exciting from the standpoint of gut physiology;it may have profound clinical implications. We consume fat a few times a day and so the MMC are activated frequently during the day. With the activation and degranulation of MMC, the gut may be an important contributor to the circulating proinflammatory mediators. We hypothesized that the absorption of lipids and the formation and secretion of chylomicrons (CMs) activate the MMCs. This action is lipid specific and is not shared by proteins or carbohydrates. We further hypothesize that acute and chronic consumption of fat, the type of fat, influence its ability to activate the MMCs and that the order of potency is omega 6 (linoleate &arachidonate) >omega 9 (oleate) >omega 3 fatty acids (linolenate). To test these hypotheses, we proposed the following studies:
Specific Aim 1. We will determine the relationship between intestinal fat absorption and MMC activation.
Sub aims : 1) to further characterize the activation of MMC by measuring the release of mast cell mediators in lymph and tissue during fat absorption, we will determine if the release of lipid mediators, cytokines, chemokines is mostly from MMC by using the mast cell deficient Ws/Ws rats;2) to determine if the presence or absence of MMC stabilizers affects intestinal uptake and lymphatic transport of dietary lipids. We will also study fat absorption in Ws/Ws rats.
Specific Aim 2. We hypothesize that the production of CMs, resulting from dietary polyunsaturated long-chain fatty acids (FA) linoleic acid (18:2, n-6) is a potent determinant of the mast cell activation and this action is differently affected by the type of fatty acids. We will determine the acute and chronic exposure to fatty acids with different degree of unsaturation and the type (n-3, n-6, and n-9) fatty acids on MMC activation by fat absorption.
Specific Aim 3. We will test our hypothesis that fatty acid or the processing of CMs by the enterocytes results in the release of factor/factors that cause the activation of the MMCs (e.g. NF-kB response). To test our hypotheses, we have proposed the following 2 subaims. 1) We will study the in vitro effects of different types of FAs on rat basophil leukemia cells (RBL-2H3 cells, a surrogate of the rat MMC) activation through NF-kB signaling pathway;2) We will study the interaction of chylous lymph and its components e.g. chylomicrons (CMs) or the media containing CMs by the intestinal epithelial cell line (Caco-2 cells) on RBC-2H3 cell NF-kB response. If the outcome is positive, we will isolate the factor/factors involved.

Public Health Relevance

By focusing on the relationship between fat absorption and mucosal mast cell degranulation, our proposed studies will identify the role of gut-derived inflammatory factors in the normal process of dietary fat absorption and transport, identify which inflammatory agents are generated by normal fat absorption and may enter the general circulation, and contribute to the etiology of various diseases such as diabetes, metabolic syndrome, and atherosclerosis and coronary heart disease. Our results will also greatly enhance our understanding of function of gastrointestinal lymphatics in health and disease by clarifying the changes which occur in GI lymph parameters during normal physiological states such as fasting and lipid absorption, laying the ground work for future studies comparing the differences in lymph between diseased states and normal physiological states.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK092138-04
Application #
8694015
Study Section
Clinical, Integrative and Molecular Gastroenterology Study Section (CIMG)
Program Officer
Carrington, Jill L
Project Start
2011-07-01
Project End
2015-05-31
Budget Start
2014-07-01
Budget End
2015-05-31
Support Year
4
Fiscal Year
2014
Total Cost
Indirect Cost
Name
University of Cincinnati
Department
Pathology
Type
Schools of Medicine
DUNS #
City
Cincinnati
State
OH
Country
United States
Zip Code
45221
Li, Xiaoming; Wang, Fei; Xu, Min et al. (2017) ApoA-IV improves insulin sensitivity and glucose uptake in mouse adipocytes via PI3K-Akt Signaling. Sci Rep 7:41289
Zhang, Yupeng; He, Jing; Zhao, Jing et al. (2017) Effect of ApoA4 on SERPINA3 mediated by nuclear receptors NR4A1 and NR1D1 in hepatocytes. Biochem Biophys Res Commun 487:327-332
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Wang, Fei; Yang, Qing; Huesman, Sarah et al. (2015) The role of apolipoprotein A-IV in regulating glucagon-like peptide-1 secretion. Am J Physiol Gastrointest Liver Physiol 309:G680-7
Li, Xiaoming; Xu, Min; Wang, Fei et al. (2015) Interaction of ApoA-IV with NR4A1 and NR1D1 Represses G6Pase and PEPCK Transcription: Nuclear Receptor-Mediated Downregulation of Hepatic Gluconeogenesis in Mice and a Human Hepatocyte Cell Line. PLoS One 10:e0142098
Zhang, Linda S; Xu, Min; Yang, Qing et al. (2015) Apolipoprotein A-V deficiency enhances chylomicron production in lymph fistula mice. Am J Physiol Gastrointest Liver Physiol 308:G634-42
Zhang, Linda S; Xu, Min; Yang, Qing et al. (2015) ABCG5/G8 deficiency in mice reduces dietary triacylglycerol and cholesterol transport into the lymph. Lipids 50:371-9
Wang, Fei; Kohan, Alison B; Dong, H Henry et al. (2014) Overexpression of apolipoprotein C-III decreases secretion of dietary triglyceride into lymph. Physiol Rep 2:e00247
Li, Xiaoming; Xu, Min; Wang, Fei et al. (2014) Apolipoprotein A-IV reduces hepatic gluconeogenesis through nuclear receptor NR1D1. J Biol Chem 289:2396-404
Poole, Daniel P; Lee, Mike; Tso, Patrick et al. (2014) Feeding-dependent activation of enteric cells and sensory neurons by lymphatic fluid: evidence for a neurolymphocrine system. Am J Physiol Gastrointest Liver Physiol 306:G686-98

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