In rodents, the enzyme CYP2E1 is required for fructose to cause damage to the intestinal barrier and inflammation in the liver. Without this enzyme, these effects do not occur.
Mechanism
Synthesis from 1 study
Fructose turns on a specific enzyme that creates damaging chemicals in the gut, breaking the seals between cells and letting bacteria leak into the blood. These bacteria then trigger scarring in the liver and disrupt its ability to process fat. Without this enzyme, none of this damage occurs, even...
Most probable mechanism
When fructose is consumed, it causes a specific enzyme in the gut to become more active, which generates harmful chemicals that damage the tight seals between gut cells. This lets bacteria and their toxins leak into the bloodstream. These toxins then travel to the liver, where they activate cells that produce scar tissue, while also disabling a key regulator that helps the liver burn fat and maintain energy balance. Without this enzyme, none of this damage happens, even with the same amount of fructose.
Fructose consumption increases the expression and activity of CYP2E1 in intestinal epithelial cells
Elevated CYP2E1 generates reactive oxygen and nitrogen species, leading to tyrosine nitration of tight and adherent junction proteins
Nitrated junctional proteins are tagged with ubiquitin and degraded by the proteasome, disrupting the intestinal epithelial barrier
Loss of barrier integrity increases paracellular permeability, allowing bacterial endotoxin to translocate into the portal circulation
Circulating endotoxin binds to TLR4 receptors on hepatic stellate cells, triggering their activation into collagen-producing myofibroblasts
Activated stellate cells deposit extracellular matrix proteins, initiating liver fibrosis
CYP2E1-mediated nitrative stress in the liver causes tyrosine nitration and proteasomal degradation of Sirt1
Loss of Sirt1 reduces deacetylation of PGC1-α and PPARα, impairing mitochondrial fatty acid oxidation and promoting lipid accumulation
Mitochondrial dysfunction and lipid overload further promote stellate cell activation and fibrotic signaling
CYP2E1-driven oxidative stress activates JNK signaling in enterocytes, increasing Bax expression and caspase-3 cleavage, leading to epithelial cell apoptosis
Evidence from Studies
Supporting (1)
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Fructose Promotes Leaky Gut, Endotoxemia and Liver Fibrosis through CYP2E1-Mediated Oxidative and Nitrative Stress
Contradicting (0)
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