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A Hypomethylating Ketogenic Diet in Apolipoprotein E-Deficient Mice: A Pilot Study on Vascular Effects and Specific Epigenetic Changes

Hyperhomocysteneinemia (HHcy) is common in the general population and is a risk factor for atherosclerosis by mechanisms that are still elusive. A hypomethylated status of epigenetically relevant targets may contribute to the vascular toxicity associated with HHcy. Ketogenic diets (KD) are diets wit...

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Autores principales: Castro, Rita, Whalen, Courtney A., Gullette, Sean, Mattie, Floyd J., Florindo, Cristina, Heil, Sandra G., Huang, Neil K., Neuberger, Thomas, Ross, A. Catharine
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2021
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8537671/
https://www.ncbi.nlm.nih.gov/pubmed/34684577
http://dx.doi.org/10.3390/nu13103576
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author Castro, Rita
Whalen, Courtney A.
Gullette, Sean
Mattie, Floyd J.
Florindo, Cristina
Heil, Sandra G.
Huang, Neil K.
Neuberger, Thomas
Ross, A. Catharine
author_facet Castro, Rita
Whalen, Courtney A.
Gullette, Sean
Mattie, Floyd J.
Florindo, Cristina
Heil, Sandra G.
Huang, Neil K.
Neuberger, Thomas
Ross, A. Catharine
author_sort Castro, Rita
collection PubMed
description Hyperhomocysteneinemia (HHcy) is common in the general population and is a risk factor for atherosclerosis by mechanisms that are still elusive. A hypomethylated status of epigenetically relevant targets may contribute to the vascular toxicity associated with HHcy. Ketogenic diets (KD) are diets with a severely restricted amount of carbohydrates that are being widely used, mainly for weight-loss purposes. However, studies associating nutritional ketosis and HHcy are lacking. This pilot study investigates the effects of mild HHcy induced by nutritional manipulation of the methionine metabolism in the absence of dietary carbohydrates on disease progression and specific epigenetic changes in the apolipoprotein-E deficient (apoE(–/–)) mouse model. ApoE(–/–) mice were either fed a KD, a diet with the same macronutrient composition but low in methyl donors (low methyl KD, LMKD), or control diet. After 4, 8 or 12 weeks plasma was collected for the quantification of: (1) nutritional ketosis, (i.e., the ketone body beta-hydroxybutyrate using a colorimetric assay); (2) homocysteine by HPLC; (3) the methylating potential S-adenosylmethionine to S-adenosylhomocysteine ratio (AdoHcy/AdoMet) by LC-MS/MS; and (4) the inflammatory cytokine monocyte chemoattractant protein 1 (MCP1) by ELISA. After 12 weeks, aortas were collected to assess: (1) the vascular AdoHcy/AdoMet ratio; (2) the volume of atherosclerotic lesions by high-field magnetic resonance imaging (14T-MRI); and (3) the content of specific epigenetic tags (H3K27me3 and H3K27ac) by immunofluorescence. The results confirmed the presence of nutritional ketosis in KD and LMKD mice but not in the control mice. As expected, mild HHcy was only detected in the LMKD-fed mice. Significantly decreased MCP1 plasma levels and plaque burden were observed in control mice versus the other two groups, together with an increased content of one of the investigated epigenetic tags (H3K27me3) but not of the other (H3K27ac). Moreover, we are unable to detect any significant differences at the p < 0.05 level for MCP1 plasma levels, vascular AdoMet:AdoHcy ratio levels, plaque burden, and specific epigenetic content between the latter two groups. Nevertheless, the systemic methylating index was significantly decreased in LMKD mice versus the other two groups, reinforcing the possibility that the levels of accumulated homocysteine were insufficient to affect vascular transmethylation reactions. Further studies addressing nutritional ketosis in the presence of mild HHcy should use a higher number of animals and are warranted to confirm these preliminary observations.
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spelling pubmed-85376712021-10-24 A Hypomethylating Ketogenic Diet in Apolipoprotein E-Deficient Mice: A Pilot Study on Vascular Effects and Specific Epigenetic Changes Castro, Rita Whalen, Courtney A. Gullette, Sean Mattie, Floyd J. Florindo, Cristina Heil, Sandra G. Huang, Neil K. Neuberger, Thomas Ross, A. Catharine Nutrients Article Hyperhomocysteneinemia (HHcy) is common in the general population and is a risk factor for atherosclerosis by mechanisms that are still elusive. A hypomethylated status of epigenetically relevant targets may contribute to the vascular toxicity associated with HHcy. Ketogenic diets (KD) are diets with a severely restricted amount of carbohydrates that are being widely used, mainly for weight-loss purposes. However, studies associating nutritional ketosis and HHcy are lacking. This pilot study investigates the effects of mild HHcy induced by nutritional manipulation of the methionine metabolism in the absence of dietary carbohydrates on disease progression and specific epigenetic changes in the apolipoprotein-E deficient (apoE(–/–)) mouse model. ApoE(–/–) mice were either fed a KD, a diet with the same macronutrient composition but low in methyl donors (low methyl KD, LMKD), or control diet. After 4, 8 or 12 weeks plasma was collected for the quantification of: (1) nutritional ketosis, (i.e., the ketone body beta-hydroxybutyrate using a colorimetric assay); (2) homocysteine by HPLC; (3) the methylating potential S-adenosylmethionine to S-adenosylhomocysteine ratio (AdoHcy/AdoMet) by LC-MS/MS; and (4) the inflammatory cytokine monocyte chemoattractant protein 1 (MCP1) by ELISA. After 12 weeks, aortas were collected to assess: (1) the vascular AdoHcy/AdoMet ratio; (2) the volume of atherosclerotic lesions by high-field magnetic resonance imaging (14T-MRI); and (3) the content of specific epigenetic tags (H3K27me3 and H3K27ac) by immunofluorescence. The results confirmed the presence of nutritional ketosis in KD and LMKD mice but not in the control mice. As expected, mild HHcy was only detected in the LMKD-fed mice. Significantly decreased MCP1 plasma levels and plaque burden were observed in control mice versus the other two groups, together with an increased content of one of the investigated epigenetic tags (H3K27me3) but not of the other (H3K27ac). Moreover, we are unable to detect any significant differences at the p < 0.05 level for MCP1 plasma levels, vascular AdoMet:AdoHcy ratio levels, plaque burden, and specific epigenetic content between the latter two groups. Nevertheless, the systemic methylating index was significantly decreased in LMKD mice versus the other two groups, reinforcing the possibility that the levels of accumulated homocysteine were insufficient to affect vascular transmethylation reactions. Further studies addressing nutritional ketosis in the presence of mild HHcy should use a higher number of animals and are warranted to confirm these preliminary observations. MDPI 2021-10-13 /pmc/articles/PMC8537671/ /pubmed/34684577 http://dx.doi.org/10.3390/nu13103576 Text en © 2021 by the authors. https://creativecommons.org/licenses/by/4.0/Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Castro, Rita
Whalen, Courtney A.
Gullette, Sean
Mattie, Floyd J.
Florindo, Cristina
Heil, Sandra G.
Huang, Neil K.
Neuberger, Thomas
Ross, A. Catharine
A Hypomethylating Ketogenic Diet in Apolipoprotein E-Deficient Mice: A Pilot Study on Vascular Effects and Specific Epigenetic Changes
title A Hypomethylating Ketogenic Diet in Apolipoprotein E-Deficient Mice: A Pilot Study on Vascular Effects and Specific Epigenetic Changes
title_full A Hypomethylating Ketogenic Diet in Apolipoprotein E-Deficient Mice: A Pilot Study on Vascular Effects and Specific Epigenetic Changes
title_fullStr A Hypomethylating Ketogenic Diet in Apolipoprotein E-Deficient Mice: A Pilot Study on Vascular Effects and Specific Epigenetic Changes
title_full_unstemmed A Hypomethylating Ketogenic Diet in Apolipoprotein E-Deficient Mice: A Pilot Study on Vascular Effects and Specific Epigenetic Changes
title_short A Hypomethylating Ketogenic Diet in Apolipoprotein E-Deficient Mice: A Pilot Study on Vascular Effects and Specific Epigenetic Changes
title_sort hypomethylating ketogenic diet in apolipoprotein e-deficient mice: a pilot study on vascular effects and specific epigenetic changes
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8537671/
https://www.ncbi.nlm.nih.gov/pubmed/34684577
http://dx.doi.org/10.3390/nu13103576
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