Role of Gut Microecology in the Pathogenesis of Drug-Induced Liver Injury and Emerging Therapeutic Strategies

Abstract

Drug-induced liver injury (DILI) is a common clinical pharmacogenic disease. In the United States and Europe, DILI is the most common cause of acute liver failure. Drugs can cause hepatic damage either directly through inherent hepatotoxic properties or indirectly by inducing oxidative stress, immune responses, and inflammatory processes. These pathways can culminate in hepatocyte necrosis. The role of the gut microecology in human health and diseases is well recognized. Recent studies have revealed that the imbalance in the gut microecology is closely related to the occurrence and development of DILI. The gut microecology plays an important role in liver injury caused by different drugs. Recent research has revealed significant changes in the composition, relative abundance, and distribution of gut microbiota in both patients and animal models with DILI. Imbalance in the gut microecology causes intestinal barrier destruction and microorganism translocation; the alteration in microbial metabolites may initiate or aggravate DILI, and regulation and control of intestinal microbiota can effectively mitigate drug-induced liver injury. In this paper, we provide an overview on the present knowledge of the mechanisms by which DILI occurs, the common drugs that cause DILI, the gut microbiota and gut barrier composition, and the effects of the gut microbiota and gut barrier on DILI, emphasizing the contribution of the gut microecology to DILI.

Keywords: drug-induced liver injury; gut microbiota; gut microecology; molecular mechanisms.

Figure 1

The molecular mechanisms of DILI. Direct hepatotoxicity is caused by agents that are intrinsically toxic to the liver. The incidence of idiosyncratic liver injury is predominantly related to the unique physiological constitution of the patient. Indirect hepatotoxicity of drugs refers to liver toxicity that is secondary to the pharmacological effects of a medication, rather than being an inherent or specific hepatotoxic quality of the drug itself. The arrows down indicate downregulation.

Figure 2

Intestinal microbiome influences DILI. When the intestinal barrier is compromised, translocated bacteria and microbial toxins can gain axis to distant sites. Bacteria, their metabolites, and PAMPs can enter the portal circulation and access the liver, exacerbating DILI. TLRs are multiprotein complexes that recognize PAMPs such as bacterial peptidoglycans (PGN) or lipopolysaccharide (LPS), double-stranded DNA and RNA (dsDNA, dsRNA), and lipoteichoic acid (LTA). SCFAs, the metabolites produced by the gut microbiota, play a critical role in regulating the balance between the function and morphology of the mucosal barrier, regulating the proliferation and differentiation of mucosal cells, protecting the integrity and permeability of the mucosal barrier, and maintaining the stability of tight junctions. Portal circulation allows intestinal-derived SCFAs to flow to the liver, reducing hepatic inflammatory injury and oxidative stress. The arrows pointing up indicate upregulation and the pointing down indicate downregulation.