Bongseok Jung & Jun Yan He

Updated: Dec 31, 2019

A Novel Proposal for Nonalcoholic Steatohepatitis: Ubiquitous Compound 4-Methylimidazole Promotes Both the Classic Hallmarks of NASH and a Novel Immunoediting Pathway to to Elicit Immune-Mediated Liver Damage

Nonalcoholic Steatosishepatitis (NASH) is a chronic disease that affects 3% of Americans

where the liver becomes steatotic and inflamed. 4-Methylimidazole (4-MI) is a ubiquitous

byproduct of caramel coloring production, and as a result is frequently ingested. Recent studies have shown that 4-MI causes hepatic lipid and macrophage accumulation. Because of this, 4-MI’s ability to regulate classic genetic hallmarks of NASH along with new potential contributors to hepatic damage in NASH was tested. HepG2 (Liver) and U937 (Immune) cells were treated with 4-MI for 24 hours. Genetic analysis was conducted via RT PCR and cellular analysis of inflammatory potency and viability was conducted via Inflammatory Attachment and Trypan Blue Assay. On the molecular level 4-MI dysregulated genes to promote NASH: disrupting homeostasis, downregulating anti-inflammatory and upregulating pro-inflammatory genes. Proinflammatory gene COX2 was downregulated in HepG2, however further research revealed its pivotal role in regeneration and results demonstrated downregulation of regeneration genes. Apoptotic genes were dysregulated to promote immunoediting: tumor antigens BCL2 and MCL1 were overexpressed in HepG2 while proapoptotic FASR and FASL were upregulated in HepG2 and U937 respectively, allowing detection of hepatocytes as precancerous while opening a separate apoptotic pathway. Molecular results were supported on the cellular level; inflammatory activity increased in U937. Viability increased in HepG2 but decreased pass control with the introduction of FASL protein. Overall, this data suggests that 4-MI promotes the classic pathology of NASH: promoting steatosis and chronic inflammation. Furthermore, 4-MI encourages liver damage via immunogenic apoptosis while decreasing healing efficiency.

Keywords: 4-Methylimidazole; 4-MI; Toll-Like Receptors; TLR; Cytokines; Nonalcoholic

Steatohepatitis; NASH