Aflatoxin-associated hepatocarcinogenesis in a changing climate: the gut microbiome as a missing link in the One Health framework.

Global anthropogenic climate change is restructuring the thermohygric parameters that govern Aspergillus flavus and Aspergillus parasiticus ecology, expanding the geographic range and contamination intensity of aflatoxin in staple food crops worldwide. Aflatoxin B1, a Group 1 IARC carcinogen and the most potent naturally occurring hepatocarcinogen, undergoes CYP3A4/CYP1A2-mediated bioactivation to the exo-8,9-epoxide, which alkylates N7-guanine residues in DNA, generating AFB1-N7-guanine adducts that produce G → T transversions culminating in the TP53 R249S gain-of-function mutation, a molecular fingerprint of aflatoxin-driven hepatocellular carcinoma. Beyond direct genotoxicity, AFB1 drives mitochondrial dysfunction through oxidative phosphorylation impairment, glutathione depletion, cardiolipin peroxidation, and mitochondrial membrane potential collapse. It activates NF-κB, STAT3, and TGF-β inflammatory signaling; and engages hepatic stellate cells in fibrogenesis culminating in cirrhosis. Critically, AFB1 also disrupts the gut microbiome, depleting butyrateproducing Ruminococcaceae, Faecalibacterium prausnitzii, and Akkermansia muciniphila while expanding pro-inflammatory Proteobacteria and Enterobacteriaceae. These dysbiotic changes compromise tight junction integrity, increase intestinal permeability, elevate portal LPS, and activate hepatic TLR4/MyD88/NF-κB and NLRP3 inflammasome cascades that amplify the carcinogenic consequences of direct AFB1 genotoxicity. This review integrates mechanistic evidence from molecular toxicology, microbiome biology, immunometabolism, and systems oncology to establish a unified framework positioning gut dysbiosis as a modifiable intermediate pathway in climate-sensitive aflatoxin-driven carcinogenesis.