TLR4 and hepatocellular carcinoma: Our mechanistic understanding of the role the microbiome plays in the development of HCC has been generated mainly in preclinical models using rodents [81,82,83,84]; these studies have shown how the activation of the TLR4 signalling pathway in response to LPS, as well as the direct toxic effects of secondary bile acids (which are microbial metabolites) in the liver, promote HCC development.