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High folic acid consumption leads to pseudo-MTHFR deficiency, altered lipid metabolism, and liver injury in mice.

Christensen KE, Mikael LG, Leung KY, Lévesque N, Deng L, Wu Q, Malysheva OV, Best A, Caudill MA, Greene ND, Rozen R - Am. J. Clin. Nutr. (2015)

Bottom Line: The latter changes, which included higher nuclear sterol regulatory element-binding protein 1, higher Srepb2 messenger RNA (mRNA), lower farnesoid X receptor (Nr1h4) mRNA, and lower Cyp7a1 mRNA, would lead to greater lipogenesis and reduced cholesterol catabolism into bile.We suggest that high folic acid consumption reduces MTHFR protein and activity levels, creating a pseudo-MTHFR deficiency.This deficiency results in hepatocyte degeneration, suggesting a 2-hit mechanism whereby mutant hepatocytes cannot accommodate the lipid disturbances and altered membrane integrity arising from changes in phospholipid/lipid metabolism.

View Article: PubMed Central - PubMed

Affiliation: From the Departments of Human Genetics and Pediatrics, McGill University, and the Montreal Children's Hospital site of the McGill University Health Centre Research Institute, Montreal, Quebec, Canada (KEC, LGM, NL, LD, QW, and RR); Developmental Biology and Cancer Programme, Institute of Child Health, University College London, London, United Kingdom (K-YL and NDEG); the Division of Nutritional Sciences and Genomics, Cornell University, Ithaca, NY (OVM and MAC); and the Department of Mathematics and Statistics, McGill University, Montreal, Quebec, Canada (AB).

ABSTRACT

Background: Increased consumption of folic acid is prevalent, leading to concerns about negative consequences. The effects of folic acid on the liver, the primary organ for folate metabolism, are largely unknown. Methylenetetrahydrofolate reductase (MTHFR) provides methyl donors for S-adenosylmethionine (SAM) synthesis and methylation reactions.

Objective: Our goal was to investigate the impact of high folic acid intake on liver disease and methyl metabolism.

Design: Folic acid-supplemented diet (FASD, 10-fold higher than recommended) and control diet were fed to male Mthfr(+/+) and Mthfr(+/-) mice for 6 mo to assess gene-nutrient interactions. Liver pathology, folate and choline metabolites, and gene expression in folate and lipid pathways were examined.

Results: Liver and spleen weights were higher and hematologic profiles were altered in FASD-fed mice. Liver histology revealed unusually large, degenerating cells in FASD Mthfr(+/-) mice, consistent with nonalcoholic fatty liver disease. High folic acid inhibited MTHFR activity in vitro, and MTHFR protein was reduced in FASD-fed mice. 5-Methyltetrahydrofolate, SAM, and SAM/S-adenosylhomocysteine ratios were lower in FASD and Mthfr(+/-) livers. Choline metabolites, including phosphatidylcholine, were reduced due to genotype and/or diet in an attempt to restore methylation capacity through choline/betaine-dependent SAM synthesis. Expression changes in genes of one-carbon and lipid metabolism were particularly significant in FASD Mthfr(+/-) mice. The latter changes, which included higher nuclear sterol regulatory element-binding protein 1, higher Srepb2 messenger RNA (mRNA), lower farnesoid X receptor (Nr1h4) mRNA, and lower Cyp7a1 mRNA, would lead to greater lipogenesis and reduced cholesterol catabolism into bile.

Conclusions: We suggest that high folic acid consumption reduces MTHFR protein and activity levels, creating a pseudo-MTHFR deficiency. This deficiency results in hepatocyte degeneration, suggesting a 2-hit mechanism whereby mutant hepatocytes cannot accommodate the lipid disturbances and altered membrane integrity arising from changes in phospholipid/lipid metabolism. These preliminary findings may have clinical implications for individuals consuming high-dose folic acid supplements, particularly those who are MTHFR deficient.

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High folic acid consumption in Mthfr+/− mice may cause degeneration of hepatocytes. Hematoxylin and eosin–stained liver sections from (A) CD+/− and (B) FASD+/− mice (400× magnification). Most cells in FASD Mthfr+/− liver appear unusually large with clear patches in the cytoplasm consistent with hepatocyte degeneration. In contrast, most livers of the other 3 groups appeared normal or had only isolated abnormal cells. Examples of these unusual cells are indicated by arrows. (C) Incidence of widespread degenerating hepatocytes in diet/genotype groups (n = 7–8 per group). Both diet (P = 0.016; estimated OR: 25.0) and genotype (P = 0.009; estimated OR: 28.9) had significant effects on the incidence of widespread degeneration (exact binary logistic regression). CD, control diet; FASD, folic acid–supplemented diet.
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fig1: High folic acid consumption in Mthfr+/− mice may cause degeneration of hepatocytes. Hematoxylin and eosin–stained liver sections from (A) CD+/− and (B) FASD+/− mice (400× magnification). Most cells in FASD Mthfr+/− liver appear unusually large with clear patches in the cytoplasm consistent with hepatocyte degeneration. In contrast, most livers of the other 3 groups appeared normal or had only isolated abnormal cells. Examples of these unusual cells are indicated by arrows. (C) Incidence of widespread degenerating hepatocytes in diet/genotype groups (n = 7–8 per group). Both diet (P = 0.016; estimated OR: 25.0) and genotype (P = 0.009; estimated OR: 28.9) had significant effects on the incidence of widespread degeneration (exact binary logistic regression). CD, control diet; FASD, folic acid–supplemented diet.

Mentions: Examination of hematoxylin and eosin–stained sections revealed histologic changes associated with nonalcoholic fatty liver disease (NAFLD). Considerable numbers of unusually large cells with vacuolation of the cytoplasm, consistent with hydropic degeneration or hepatocyte ballooning, were observed (Figure 1). Both diet and genotype significantly affected the incidence of degenerating cells. However, it is clear from inspection of the data (Figure 1C) that these results are driven by the FASD Mthfr+/− group, as 6 of 7 of FASD Mthfr+/− livers presented with this phenotype, compared with a maximum of 1 of 7 in the other groups. Hydropic degeneration, caused by accumulation of fluid in the cytoplasm, is associated with disturbed membrane integrity (50). Changes in membrane integrity can result from disruption of phospholipid metabolism, because phospholipids, especially phosphatidylcholine (PtdCho), are critical components of membranes (51).


High folic acid consumption leads to pseudo-MTHFR deficiency, altered lipid metabolism, and liver injury in mice.

Christensen KE, Mikael LG, Leung KY, Lévesque N, Deng L, Wu Q, Malysheva OV, Best A, Caudill MA, Greene ND, Rozen R - Am. J. Clin. Nutr. (2015)

High folic acid consumption in Mthfr+/− mice may cause degeneration of hepatocytes. Hematoxylin and eosin–stained liver sections from (A) CD+/− and (B) FASD+/− mice (400× magnification). Most cells in FASD Mthfr+/− liver appear unusually large with clear patches in the cytoplasm consistent with hepatocyte degeneration. In contrast, most livers of the other 3 groups appeared normal or had only isolated abnormal cells. Examples of these unusual cells are indicated by arrows. (C) Incidence of widespread degenerating hepatocytes in diet/genotype groups (n = 7–8 per group). Both diet (P = 0.016; estimated OR: 25.0) and genotype (P = 0.009; estimated OR: 28.9) had significant effects on the incidence of widespread degeneration (exact binary logistic regression). CD, control diet; FASD, folic acid–supplemented diet.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4340065&req=5

fig1: High folic acid consumption in Mthfr+/− mice may cause degeneration of hepatocytes. Hematoxylin and eosin–stained liver sections from (A) CD+/− and (B) FASD+/− mice (400× magnification). Most cells in FASD Mthfr+/− liver appear unusually large with clear patches in the cytoplasm consistent with hepatocyte degeneration. In contrast, most livers of the other 3 groups appeared normal or had only isolated abnormal cells. Examples of these unusual cells are indicated by arrows. (C) Incidence of widespread degenerating hepatocytes in diet/genotype groups (n = 7–8 per group). Both diet (P = 0.016; estimated OR: 25.0) and genotype (P = 0.009; estimated OR: 28.9) had significant effects on the incidence of widespread degeneration (exact binary logistic regression). CD, control diet; FASD, folic acid–supplemented diet.
Mentions: Examination of hematoxylin and eosin–stained sections revealed histologic changes associated with nonalcoholic fatty liver disease (NAFLD). Considerable numbers of unusually large cells with vacuolation of the cytoplasm, consistent with hydropic degeneration or hepatocyte ballooning, were observed (Figure 1). Both diet and genotype significantly affected the incidence of degenerating cells. However, it is clear from inspection of the data (Figure 1C) that these results are driven by the FASD Mthfr+/− group, as 6 of 7 of FASD Mthfr+/− livers presented with this phenotype, compared with a maximum of 1 of 7 in the other groups. Hydropic degeneration, caused by accumulation of fluid in the cytoplasm, is associated with disturbed membrane integrity (50). Changes in membrane integrity can result from disruption of phospholipid metabolism, because phospholipids, especially phosphatidylcholine (PtdCho), are critical components of membranes (51).

Bottom Line: The latter changes, which included higher nuclear sterol regulatory element-binding protein 1, higher Srepb2 messenger RNA (mRNA), lower farnesoid X receptor (Nr1h4) mRNA, and lower Cyp7a1 mRNA, would lead to greater lipogenesis and reduced cholesterol catabolism into bile.We suggest that high folic acid consumption reduces MTHFR protein and activity levels, creating a pseudo-MTHFR deficiency.This deficiency results in hepatocyte degeneration, suggesting a 2-hit mechanism whereby mutant hepatocytes cannot accommodate the lipid disturbances and altered membrane integrity arising from changes in phospholipid/lipid metabolism.

View Article: PubMed Central - PubMed

Affiliation: From the Departments of Human Genetics and Pediatrics, McGill University, and the Montreal Children's Hospital site of the McGill University Health Centre Research Institute, Montreal, Quebec, Canada (KEC, LGM, NL, LD, QW, and RR); Developmental Biology and Cancer Programme, Institute of Child Health, University College London, London, United Kingdom (K-YL and NDEG); the Division of Nutritional Sciences and Genomics, Cornell University, Ithaca, NY (OVM and MAC); and the Department of Mathematics and Statistics, McGill University, Montreal, Quebec, Canada (AB).

ABSTRACT

Background: Increased consumption of folic acid is prevalent, leading to concerns about negative consequences. The effects of folic acid on the liver, the primary organ for folate metabolism, are largely unknown. Methylenetetrahydrofolate reductase (MTHFR) provides methyl donors for S-adenosylmethionine (SAM) synthesis and methylation reactions.

Objective: Our goal was to investigate the impact of high folic acid intake on liver disease and methyl metabolism.

Design: Folic acid-supplemented diet (FASD, 10-fold higher than recommended) and control diet were fed to male Mthfr(+/+) and Mthfr(+/-) mice for 6 mo to assess gene-nutrient interactions. Liver pathology, folate and choline metabolites, and gene expression in folate and lipid pathways were examined.

Results: Liver and spleen weights were higher and hematologic profiles were altered in FASD-fed mice. Liver histology revealed unusually large, degenerating cells in FASD Mthfr(+/-) mice, consistent with nonalcoholic fatty liver disease. High folic acid inhibited MTHFR activity in vitro, and MTHFR protein was reduced in FASD-fed mice. 5-Methyltetrahydrofolate, SAM, and SAM/S-adenosylhomocysteine ratios were lower in FASD and Mthfr(+/-) livers. Choline metabolites, including phosphatidylcholine, were reduced due to genotype and/or diet in an attempt to restore methylation capacity through choline/betaine-dependent SAM synthesis. Expression changes in genes of one-carbon and lipid metabolism were particularly significant in FASD Mthfr(+/-) mice. The latter changes, which included higher nuclear sterol regulatory element-binding protein 1, higher Srepb2 messenger RNA (mRNA), lower farnesoid X receptor (Nr1h4) mRNA, and lower Cyp7a1 mRNA, would lead to greater lipogenesis and reduced cholesterol catabolism into bile.

Conclusions: We suggest that high folic acid consumption reduces MTHFR protein and activity levels, creating a pseudo-MTHFR deficiency. This deficiency results in hepatocyte degeneration, suggesting a 2-hit mechanism whereby mutant hepatocytes cannot accommodate the lipid disturbances and altered membrane integrity arising from changes in phospholipid/lipid metabolism. These preliminary findings may have clinical implications for individuals consuming high-dose folic acid supplements, particularly those who are MTHFR deficient.

Show MeSH
Related in: MedlinePlus