Role of targeting TLR4 signaling axis in liver-related diseases

Chaihu Guizhi Ganjiang Decoction attenuates nonalcoholic steatohepatitis by enhancing intestinal barrier integrity and ameliorating PPARα mediated lipotoxicity

BACKGROUND

Nonalcoholic steatohepatitis (NASH) is a prominent cause of liver-related death that poses a threat to global health and is characterized by severe hepatic steatosis, lobular inflammation, and ballooning degeneration. To date, no Food and Drug Administration-approved medicine is commercially available. The Chaihu Guizhi Ganjiang Decoction (CGGD) shows potential curative effects on regulation of blood lipids and blood glucose, mitigation of organism inflammation, and amelioration of hepatic function. However, the overall regulatory mechanisms underlying its effects on NASH remain unclear.

PURPOSE

This study aimed to investigate the efficiency of CGGD on methionine- and choline-deficient (MCD)-induced NASH and unravel its underlying mechanisms.

METHODS

A NASH model of SD rats was established using an MCD diet for 8 weeks, and the efficacy of CGGD was evaluated based on hepatic lipid accumulation, inflammatory response, and fibrosis. The effects of CGGD on the intestinal barrier, metabolic profile, and differentially expressed genes (DEGs) profile were analyzed by integrating gut microbiota, metabolomics, and transcriptome sequencing to elucidate its mechanisms of action.

RESULTS

In MCD-induced NASH rats, pathological staining demonstrated that CGGD alleviated lipid accumulation, inflammatory cell infiltration, and fibrosis in the hepatic tissue. After CGGD administration, liver index, liver weight, serum alanine aminotransferase (ALT), and aspartate aminotransferase (AST) contents, liver triglycerides (TG), and free fatty acids (FFAs) were decreased, meanwhile, it down-regulated the level of proinflammatory mediators (TNF-α, IL-6, IL-1β, MCP-1), and up-regulated the level of anti-inflammatory factors (IL-4, IL-10), and the expression of liver fibrosis markers TGFβ, Acta2, Col1a1 and Col1a2 were weakened. Mechanistically, CGGD treatment altered the diversity of intestinal flora, as evidenced by the depletion of Allobaculum, Blautia, norank_f_Erysipelotrichaceae, and enrichment of the probiotic genera Roseburia, Lactobacillus, Lachnoclostridium, etc. The colonic histopathological results indicated that the gut barrier damage recovered in the CGGD treatment group, and the expression levels of colonic short-chain fatty acids (SCFAs)-specific receptors FFAR2, FFAR3, and tight junction (TJs) proteins ZO-1, Occludin, Claudin-1 were increased compared with those in the model group. Further metabolomic and transcriptomic analyses suggested that CGGD mitigated the lipotoxicity caused by glycerophospholipid and eicosanoid metabolism disorders by decreasing the levels of PLA2G4A, LPCAT1, COX2, and LOX5. In addition, CGGD could activate the inhibitory lipotoxic transcription factor PPARα, regulate the proteins of FABP1, APOC2, APOA2, and LPL to promote fatty acid catabolism, and suppress the TLR4/MyD88/NFκB pathway to attenuate NASH.

CONCLUSION

Our study demonstrated that CGGD improved steatosis, inflammation, and fibrosis on NASH through enhancing intestinal barrier integrity and alleviating PPARα mediated lipotoxicity, which makes it an attractive candidate for potential new strategies for NASH prevention and treatment.

Dahuang zhechong pill ameliorates hepatic fibrosis by regulating gut microbiota and metabolites

ETHNOPHARMACOLOGICAL RELEVANCE

DHZCP is a traditional Chinese medicinal formula in "The Synopsis of Prescriptions of the Golden Chamber" that has been often used in the treatment of hepatic disorders, gynecopathy and atherosclerosis. However, its underlying mechanisms in preventing hepatic fibrosis remain incompletely understood.

AIM OF THE STUDY

This study aims to explore the therapeutic efficacy and potential mechanism of DHZCP in a CCL4-induced experimental hepatic fibrosis rat model.

MATERIALS AND METHODS

DHZCP was orally administered at doses of 0.168, 0.084 and 0.042 g⋅kg-1⋅d-1 in a CCL4-induced hepatic fibrosis model using SD rats. Histopathology, immunohistochemistry and biochemical analysis, ELISA, Flow cytometry, WB, RT-PCR, 16 S rRNA, and untargeted metabolomic analysis were used to determine the therapeutic effects and mechanisms of DHZCP in the treatment of CCL4-induced hepatic fibrosis.

RESULTS

Pharmacodynamically, DHZCP inhibited ALT and AST, improved liver function, decreased NF-κB, TNF-α and IL-6 in liver tissue, indicating its role in inhibiting CCL4-induced liver inflammation. Most importantly, it reduces the level of fibrosis in serum and liver tissue. Histological analysis also showed that DHZCP could effectively inhibit inflammatory cytokine infiltration and excessive collagen deposition. Mechanistically, DHZCP regulates gut microbiota, improves the proportion of firmicutes and bacteroidota at the phylum level, and increases the abundance of beneficial bacteria at the genus level, such as muribagulaceae unclassified, prevotella, alloprevotella, closteriales unclassified, lachnospiraceae unclassified and phascolarctobacterium. Instead, it reduced the abundance of two harmful bacteria, desulfovibrio and colidextribacter. Four types of metabolites such as hydrocarbons, organic nitrogen compounds, organic oxygen compounds, and organosulfur compounds were added. Furthermore, DHZCP was found to reduce the damage of intestinal barrier caused by changes in gut microbiota and metabolites.

CONCLUSION

DHZCP is an effective inhibitor of hepatic fibrosis by regulating gut microbiota and metabolites, improving the integrity of the intestinal barrier.

Evodiamine alleviates DEHP-induced hepatocyte pyroptosis, necroptosis and immunosuppression in grass carp through ROS-regulated TLR4 / MyD88 / NF-κB pathway

Di (2-ethylhexyl) phthalate (DEHP) is a neuroendocrine disruptor that can cause multi-tissue organ damage by inducing oxidative stress. Evodiamine (EVO) is an indole alkaloid with anti-inflammatory, antitumor, and antioxidant pharmacological activity. In this manuscript, the effects of DEHP and EVO on the pyroptosis, necroptosis and immunology of grass carp hepatocytes (L8824) were investigated using DCFH-DA staining, PI staining, IF staining, AO/EB staining, LDH kit, qRT-PCR and protein Western blot. The results showed that DEHP exposure upregulated reactive oxygen species (ROS) levels, promoted the expression of TLR4/MyD88/NF-κB pathway, increased the expression of genes involved in cell pyroptosis pathway (LDH, NLRP3, ASC, caspase1, IL-1β, IL-18 and GSDMD) and necroptosis-related genes (RIPK1, RIPK3 and MLKL). The expression of DEHP can also affect immune function, which can be demonstrated by variationsin the activation of antimicrobial peptides (LEAP2, HEPC, and β-defensin) and inflammatory cytokines (TNF-α, IL-2, IL-6 and IL-10). EVO regulates cellular antioxidant capacity by inhibiting ROS burst, reduces DEHP-induced cell pyroptosis and necroptosis to some extent, and restores cellular immune function, after co-exposure with EVO. The TLR4 pathway was inhibited by the co-treatment of TLR4 inhibitor TLR-IN-C34 and DEHP, which attenuated the expression of cell pyroptosis, necroptosis, and immunosuppression. Thus, DEHP induced pyroptosis, necroptosis and abnormal immune function in L8824 cells by activating TLR4/MyD88/NF-κB pathway. In addition, EVO has a therapeutic effect on DEHP-induced toxic injury. This study further provides a theoretical basis for the risk assessment of plasticizer DEHP on aquatic organisms.