Progress 11/15/15 to 11/14/17
Outputs
Target Audience:The completed studies add to our knowledge regarding cardiovascular disease risk factors, dietary fat absorption, and dietary strategies for cardiovascular disease risk reduction. Therefore the target audience includes basic/clinical researchers interested in lipoprotein metabolism, apolipoproteins, and the intestine, as well as physicians and individuals who are interested in determining nutritional approaches to metabolic and cardiovascular disease. Manuscripts arising from this grant were published inpeer reviewed journals, and will be accessible via pubmed. Changes/Problems:None. What opportunities for training and professional development has the project provided?Training and Professional development: I have attended 3conferences: 1) American Physiologic Society Immunology, Inflammation, and Cardiovascular Disease conference, where my graduate student presented a poster on this topic. 2) ATVB 2016, where a second graduate student presented a poster; and 3) ATVB 2017, where my graduate student won an award for her presentation. How have the results been disseminated to communities of interest?1. Gabrielle West, Cayla Rodia, Diana Li, Zania Johnson, Hongli Dong, Alison B. Kohan. Key differences between apoC-III regulation and expression in intestine and liver. BBRC. Accepted June 2017. 2. Jattan J, Rodia C, Li D, Diakhate A, Dong H, Bataille A, Shroyer NF,Kohan AB. Using primary murine intestinal enteroids to study dietary TAG absorption, lipoprotein synthesis, and the role of apoC-III in the intestine. J Lipid Res. May;58(5):853-865, 2017.Select item 28739253 3.Gaia Botteri, Marta Montori, Anna Gumà, Javier Pizarro, Lídia Cedó, Joan Carles Escolà-Gil, Diana Li, Emma Barroso, Xavier Palomer, Alison B. Kohan, Manuel Vázquez-Carrera. VLDL and apolipoprotein CIII induce ER stress and inflammation and attenuate insulin signaling via toll-like receptor 2 and ERK1/2 in skeletal muscle cells. Diabetelogia. Accepted June 2017. 4. Li, D., Dong, H., Kohan A.B.The Isolation, Culture, and Propagation of Murine Intestinal Enteroids for the Study of Dietary Lipid Metabolism. Methods Mol Biol. 2017 Sep 20. doi: 10.1007/7651_2017_69. (Epub ahead of print) What do you plan to do during the next reporting period to accomplish the goals?N/A
Impacts
What was accomplished under these goals?
We have found the following as part of this work: 1) ApoC-III is a critical cardiovascular risk factor, and humans expressing null mutations in apoC-III are robustly protected from cardiovascular disease. Because of its critical role in elevating plasma lipids and CVD risk, hepatic apoC-III regulation has been studied at length. Considerably less is known about the factors that regulate intestinal apoC-III. We used primary murine enteroids, Caco-2cells, and dietary studies in wild-type mice to show that intestinal apoC-III expression does not change in response to fatty acids, glucose, or insulin administration, in contrast to hepatic apoC-III. Intestinal apoC-III is not sensitive to changes in FoxO1 expression (which is itself very low in the intestine, as is FoxO1 target IGFBP-1), nor is intestinal apoC-III responsive to western diet, a significant contrast to hepatic apoC-III stimulation during western diet. These data strongly suggest that intestinal apoC-III is not a FoxO1 target and support the idea that apoC-III is not regulated coordinately with hepatic apoC-III, and establishesanother key aspect of apoC-III that is unique in the intestine from the liver. We showed that enteroids can be used to elucidate intestinal mechanisms behind CVD risk factors, including tissue-specific apolipoprotein functions. Using enteroids, we show that intestinal apoC-III overexpression results in the secretion of smaller, less dense chylomicron particles along with reduced triacylglycerol secretion from the intestine. This model significantly expands our ability to test how specific genes or genetic polymorphisms function in dietary fat absorption and the precise intestinal mechanisms that are critical in the etiology of metabolic disease. 3) We have found that apoC-III is a critical modulator of lipid metabolism in immune cells in the intestine, and these cells, when stimulated with apoC-III become activated to dampen inflammation in the gut. We have now determined that mice expressing the human form of apoC-III (apoC-III transgenic (apoC-IIITg) mice) are highly resistant to colitis (induced with dextran-sulfate sodium (DSS), **P<0.001), and are resistant to all associated pathologies including weight loss, colon shortening, macroscopic damage, diarrhea, and pro-inflammatory secretion of IL-17. We have determined that this dramatic protection from colitis includes a significant increase in anti-inflammatory cytokine IL-10 and in the number of intestinally resident CD4+CD25+FOXP3+Tregs, a unique subset of Tregs that are optimally suppressive in the intestinal system. We have identified in vitro that both WT and apoC-IIITg Tregs proliferate rapidly in response to physiologically high levels of plasma apoC-III.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2017
Citation:
Li D., Dong H., Kohan A.B. (2017) The Isolation, Culture, and Propagation of Murine Intestinal Enteroids for the Study of Dietary Lipid Metabolism. In: . Methods in Molecular Biology. Humana Press
- Type:
Journal Articles
Status:
Published
Year Published:
2017
Citation:
Botteri G, Montori M, Gum� A, Pizarro J, Ced� L, Escol�-Gil JC, Li D, Barroso E, Palomer X, Kohan AB, V�zquez-Carrera M.VLDL and apolipoprotein CIII induce ER stress and inflammation and attenuate insulin signalling via Toll-like receptor 2 in mouse skeletal muscle cells.Diabetologia. 2017 Aug 23. doi: 10.1007/s00125-017-4401-5. [Epub ahead of print]
- Type:
Journal Articles
Status:
Published
Year Published:
2017
Citation:
Jattan J, Rodia C, Li D, Diakhate A, Dong H, Bataille A, Shroyer NF, Kohan AB. Using primary murine intestinal enteroids to study dietary TAG absorption, lipoprotein synthesis, and the role of apoC-III in the intestine. J Lipid Res. May;58(5):853-865, 2017.
- Type:
Journal Articles
Status:
Published
Year Published:
2017
Citation:
Gabrielle West, Cayla Rodia, Diana Li, Zania Johnson, Hongli Dong, Alison B. Kohan. Key differences between apoC-III regulation and expression in intestine and liver. BBRC. Accepted June 2017.
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Progress 11/15/15 to 11/14/16
Outputs
Target Audience:The proposed studies will add to our knowledge regarding cardiovascular disease risk factors, dietary fat absorption, and dietary strategies for cardiovascular disease risk reduction. Therefore the target audience includes basic/clinical researchers interested in lipoprotein metabolism, apolipoproteins, and the intestine, as well as physicians and individuals who are interested in determining nutritional approaches to metabolic and cardiovascular disease. A manuscript arising from this grant has been submitted to a peer reviewed journal, and will be accessible via pubmed should it be accepted. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Training and Professional development: I have co-created (with Dr. Annabelle Rodriguez-Oquendo at UConn Health Center) the Immuno-Cardiovascular Working Group (ICWG), which meets monthly in Farmington to bring together a diverse group of UConn and Jackson Labs researchers in genetics, immunology, and metabolism. The ICWG is beginning its 2nd year, and the group is beginning to collaborate through publications in an effort to ultimately submit grants that bridge our disparate research efforts. I have also attended 2 conferences: 1) American Physiologic Society Immunology, Inflammation, and Cardiovascular Disease conference, where my graduate student presented a poster on this topic. 2) ATVB 2016, where a second graduate student presented a poster How have the results been disseminated to communities of interest?Abstracts arising during this funding period: Cayla R, West G, Li D, Jellison E, Kohan AB. Identification of an additional role for apoC-III in atherogenesis: overexpression of apoC-III modulates basal T cell profile in mice. American Physiological Society: Immunity, Inflammation, and Cardiovascular Disease, Westminster, CO, 2016. West G, Rodia C, Li D, Jattan K, Dong H, Kohan AB. The Regulation of Intestinal apoC-III by Dietary Fat: Key Differences from Hepatic apoC-III Regulation and Implications for Lipoprotein Synthesis and Secretion. Arteriosclerosis, Thrombosis and Vascular Biology Scientific Sessions, Nashville, TN, 2016. What do you plan to do during the next reporting period to accomplish the goals?In year 2 of this project, we plan to accomplish the following goals: 1) We will complete the 12-week diet studies, and complete our comparison of apoC-III regulation between the liver and intestine in response to diet. These studies will thoroughly determine how intestinal apoC-III is regulated, and allow us to compare tissue-resident macrophage and T cell populations in the intestine when apoC-III expression is altered. 2) We plan to further determine how apoC-III is altering T cell speciation, and whether this requires apoC-III, or simply the high plasma triglycerides that accompany high apoC-III levels. Additionally, whether diets that include high levels of fish oil are protected from these T cell speciation changes is a major goal of the 2nd year of funding.
Impacts
What was accomplished under these goals?
In year 1 of this project, we made major strides towards our stated goals. Specifically: 1) We hypothesized that intestinal apoC-III is down-regulated by dietary intake of DHA via inhibition of FoxO1. We found that duodenal apoC-III is particularly responsive to chronic low fat, high carbohydrate feeding. ChREBP appears to be implicated in the increased expression of apoC-III in response to dietary carbohydrate. These results also confirm that fish oil feeding reduces hepatic apoC-III gene expression. However, the mechanism by which intestinal apoC-III expression is blunted by fish oil remains to be elucidated. In the course of these studies, we have found it necessary to culture primary mouse hepatocytes, both from wild-type and human apoC-III transgenic mice. This additional model enables us to dissect out the differences in regulation between the liver and intestine, and how diet plays into this. We have also taken on a 12-week dietary challenge, in order to see whether raising plasma lipids via western diet may change the regulation of apoC-III in wild-type mice. We are preparing this data for publication. 2) We have undertaken LPS-treatment of wild-type mice, as well as mice overexpressing apoC-III. Interestingly, we have not found any differences in macrophage activation in response to changes in apoC-III levels. Since atherogenesis has been associated with increased activated T-cells and differentiation of T-cells in to pro-inflammatory subsets, we have also discovered a potential role for apoC-III, or the resulting hypertriglyceridemia, in the speciation of circulating T cells. This has involved a novel technique for our lab, flow cytometry, and we are currently preparing this manuscript.
Publications
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