Toll-like receptor 2 activation in monocytes contributes to systemic inflammation and alcohol-associated liver disease in humans

AHCC inhibited hepatic stellate cells activation by regulation of cytoglobin induction via TLR2-SAPK/JNK pathway and collagen production via TLR4-NF-κβ pathway

Cirrhosis, which represents the end stage of liver fibrosis, remains a life-threatening condition without effective treatment. Therefore, prevention of the progression of liver fibrosis through lifestyle habits such as diet and exercise is crucial. The functional food AHCC, a standardized extract of cultured Lentinula edodes mycelia produced by Amino Up Co., Ltd. (Sapporo, Japan)] has been reported to be effective in improving the pathophysiology of various liver diseases. In this study, the aim was to analyze the influence of AHCC on hepatic stellate cells, which are responsible for liver fibrosis. Eight-week-old male C57BL6/j mice were induced with liver fibrosis by intraperitoneal injection of carbon tetrachloride. Simultaneously, they were orally administered 3% AHCC to investigate its impact on the progression of liver fibrosis. Using the human hepatic stellate cell (HHSteC) line, we analyzed the influence of AHCC on the expression of molecules related to hepatic stellate cell activation. The administration of AHCC resulted in reduced expression of collagen1a, α smooth muscle actin (αSMA), and heat shock protein 47 in the liver. Furthermore, the expression of cytoglobin, a marker for quiescent hepatic stellate cells, was enhanced. In vitro study, it was confirmed that AHCC inhibited αSMA by inducing cytoglobin via upregulating the stress-activated protein kinase/Jun NH2-terminal kinase (SAPK/JNK) pathway through Toll-like receptor (TLR) 2. In addition, AHCC suppressed collagen1a production by hepatic stellate cells through TLR4-NF-κβ pathway. AHCC was suggested to suppress hepatic fibrosis by inhibition of hepatic stellate cells activation. Daily intake of AHCC from mild fibrotic stages may have the potential to prevent the progression of liver fibrosis.NEW & NOTEWORTHY AHCC, a standardized extract of cultured Lentinula edodes mycelia, suppresses liver fibrosis progression by induction of cytoglobin via the Toll-like receptor 2 (TLR2)-stress-activated protein kinase/Jun NH2-terminal kinase (SAPK/JNK) pathway and the inhibition of collagen production via the TLR4-NFκβ pathway in hepatic stellate cells. Daily oral administration of AHCC from the stage of MASLD may have the potential to prevent disease progression to MASH with fibrosis.

Polyethylene microplastics induced gut microbiota dysbiosis leading to liver injury via the TLR2/NF-κB/NLRP3 pathway in mice

Microplastics (MPs) are ubiquitous environmental contaminants that have negative impacts on health and safety. The gut microbiota plays multiple roles as a newly discovered virtual metabolic organ. The objective of this study was to investigate the potential of MPs to cause liver injury by disrupting the balance of gut microbiota. The results indicated that exposure to MPs resulted in liver damage and disrupted the homeostasis of gut microbiota. MPs significantly reduced the liver organ coefficient, leading to liver cell injury and impaired function. Additionally, there was an increase in the expression of fibril-related proteins, which positively correlated with MPs concentration. Furthermore, MPs increased the relative abundances of Desulfovibrio, Clostridia, Enterorhabdus, Bacteroides, and Gemella while decreasing the abundance of Dubosoella. Different concentrations of MPs exhibited varying effects on specific bacterial groups, however, both concentrations resulted in an increase in pathogenic bacteria and a decrease in beneficial bacteria, as well as alterations in microbial structure. Moreover, MPs induced oxidative stress, inflammation, apoptosis and necrosis in liver cells. The study found that MPs disrupted gut microbiota homeostasis and activated TLR2/NF-κB/NLRP3 pathway in the liver, providing a new insight into the mechanism underlying MPs-induced liver injury. These findings serve as a warning regarding environmental pollution caused by MPs.

Ambiguous Pathogenic Roles of Macrophages in Alcohol-Associated Liver Diseases

Alcohol-associated liver disease (ALD) represents a major public health issue worldwide and is a leading etiology of liver cirrhosis. Alcohol-related liver injuries include a range of manifestations including alcoholic hepatitis (AH), simple steatosis, steatohepatitis, hepatic fibrosis, cirrhosis and liver cancer. Liver disease occurs from several pathological disturbances such as the metabolism of ethanol, which generates reactive oxygen species (ROS) in hepatocytes, alterations in the gut microbiota, and the immune response to these changes. A common hallmark of these liver affections is the establishment of an inflammatory environment, and some (broad) anti-inflammatory approaches are used to treat AH (eg, corticosteroids). Macrophages, which represent the main innate immune cells in the liver, respond to a wide variety of (pathogenic) stimuli and adopt a large spectrum of phenotypes. This translates to a diversity of functions including pathogen and debris clearance, recruitment of other immune cells, activation of fibroblasts, or tissue repair. Thus, macrophage populations play a crucial role in the course of ALD, but the underlying mechanisms driving macrophage polarization and their functionality in ALD are complex. In this review, we explore the various populations of hepatic macrophages in alcohol-associated liver disease and the underlying mechanisms driving their polarization. Additionally, we summarize the crosstalk between hepatic macrophages and other hepatic cell types in ALD, in order to support the exploration of targeted therapeutics by modulating macrophage polarization.