In rats and mice given a high-fructose drink for eight weeks, researchers observed reduced levels of key proteins that maintain intestinal barrier integrity, increased chemical modifications to these...
Mechanism
Synthesis from 1 study
Too much fructose turns on a harmful enzyme in the gut and liver, which creates toxic chemicals that break down the glue holding gut cells together. This lets bacteria toxins leak into the blood, which then scar the liver. At the same time, the same toxins disable a protective liver protein,...
Most probable mechanism
When a lot of fructose is consumed, it triggers a chain reaction in the gut: a specific enzyme becomes overactive, producing harmful chemicals that damage the proteins holding gut cells together. These damaged proteins are marked for destruction and broken down, causing the gut to become leaky. Toxins from gut bacteria then escape into the bloodstream and reach the liver, where they activate cells that produce scar tissue. At the same time, the same harmful chemicals in the liver disable a key protective protein, which leads to fat buildup and more scarring. Without that enzyme, none of this damage happens.
Fructose consumption increases expression and activity of CYP2E1 in intestinal epithelial cells and hepatocytes
CYP2E1 generates reactive oxygen and nitrogen species, leading to nitration of tyrosine residues on tight and adherent junction proteins in the intestinal epithelium
Nitrated junctional proteins are tagged with ubiquitin and degraded by the proteasome, reducing their abundance and disrupting epithelial barrier integrity
Loss of junctional proteins increases paracellular permeability, allowing bacterial endotoxin to translocate from the gut lumen into systemic circulation
Circulating endotoxin binds to Toll-like receptor 4 on hepatic stellate cells, triggering their activation into collagen-producing myofibroblasts
Activated hepatic stellate cells deposit extracellular matrix proteins, including collagen-1 and collagen-4, leading to fibrotic scar formation
CYP2E1-driven nitrative stress in the liver causes tyrosine nitration and ubiquitin-mediated degradation of Sirt1, reducing its deacetylase activity
Loss of Sirt1 increases histone acetylation and suppresses PGC1-α and PPARα signaling, impairing mitochondrial fatty acid oxidation and promoting lipid accumulation
Lipid accumulation and mitochondrial dysfunction synergize with endotoxin-driven inflammation to amplify hepatic stellate cell activation and fibrosis progression
CYP2E1-mediated oxidative stress in intestinal epithelial cells activates JNK signaling, upregulates Bax, and induces caspase-3-dependent enterocyte apoptosis, further compromising barrier integrity
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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