Targeting FOXO3a, TLR2/MyD88/NF-κB cascade, and ferroptosis by theaflavin ameliorates iron-elicited liver toxicity

While iron is essential in trace amounts, elevated level represents a serious health problem. Elevated iron level arises as a secondary consequence to hemochromatosis and anemias that necessitate frequent blood transfusions, leading to organ toxicity, particularly liver toxicity.

The current study investigated the potential ameliorating impact of theaflavin against the iron-elicited liver toxicity. A model of iron intoxication was established in male Wistar rats, and theaflavin was given over a 10-day period. Blood and liver specimens were collected and subjected to histopathological, ELISA, biochemical, and Western blotting investigations.

Theaflavin suppressed the iron-evoked liver injury as indicated by a significant decrease in activity of the hepatocellular enzymes in sera and improved hepatic histopathological architecture. Theaflavin activated the antioxidant transcription factor FOXO3a with upregulation of its responsive antioxidant gene products including thioredoxin reductase, superoxide dismutase, and catalase, along with reduced DNA oxidative modification. Equally important, theaflavin suppressed TLR2 inflammatory cascade as evidenced by a significant downregulation in protein expression of TLR2 and its adaptor protein MyD88, and inhibition of phosphorylation and nuclear translocation of its downstream inflammatory transcription factor NF-κB. In the same context, theaflavin markedly reduced levels of NF-κB-responsive cytokines TNF-α and IL-6. Interestingly, theaflavin repressed the iron-elicited hepatocellular ferroptosis as indicated by modulation of its biomarkers GPx4 and COX-2 protein expression, and levels of lipid hydroperoxides and hepatocellular iron load.

These findings emphasize the ameliorating impact of theaflavin against the iron-elicited liver toxicity and shed light on FOXO3a, TLR2/MyD88/NF-κB cascade, and ferroptosis as possible molecular targets.