Trigonelline regulates glycolysis and energy metabolism during hepatic fibrosis via Glut-1-HIF-1α axis: Focusing the interaction of macrophages and HSCs

Hepatic fibrosis is a pathological process caused by acute or chronic liver injury and inflammation, such as viral infection, alcoholic and non-alcoholic steatohepatitis, and accompanied by excessive accumulation of extracellular matrix (ECM) (Kisseleva and Brenner, 2021). If not effectively treated, hepatic fibrosis progressively impairs normal liver regeneration and increases the risk of liver failure, which may further develop into cirrhosis or even hepatocellular carcinoma (Banerjee and Farci, 2024). Transdifferentiation of quiescent hepatic stellate cells (HSCs) into myofibroblast-like activated HSCs generates large ECM deposits, including α-smooth muscle actin (α-SMA), fibronectin and collagen, thereby driving hepatic fibrosis (Jiang et al., 2024; Dou et al., 2024). HSCs activation is influenced by the complex hepatic microenvironment and is mainly attributed to direct or indirect crosstalk between hepatocytes and a variety of tissue-resident cells. Studies have shown that when hepatocytes are injured, adjacent Kupffer cells form a chronic inflammatory microenvironment by continuously secreting inflammatory cytokines, which in turn promotes HSCs activation (Tacke et al., 2023). Therefore, inhibition of HSCs activation, hepatic inflammation, and improving liver microenvironment may be an effective strategy to ameliorate hepatic fibrosis.

A growing number of studies have reported that dysregulation of aerobic glycolysis and energy metabolism is closely associated with the progression of liver fibrosis (Yang et al., 2023). Recent understanding revels that activated HSCs requires metabolic reprogramming and continuous energy supply, while aerobic glycolysis is an important metabolic feature of activated HSCs, a process like the Warburg effect in tumor cells (Vallée et al., 2017). The activated HSCs prefer glycolysis pathway rather than oxidative phosphorylation as cell energy metabolism method, which may be due to the metabolic pathway of glycolysis is relatively short, and rapidly generate adenosine triphosphate (ATP) to meet the high demands of HSCs proliferation and activation (Hou et al., 2018). Notably, the occurrence of glycolysis depends on high levels of glucose ingestion. Glucose transporter 1 (Glut-1) is a widely distributed glucose transporter, mainly responsible for glucose transport by membrane translocation to maintain the operation of glycolysis (Wei et al., 2022). Changes in cell metabolism can regulate the expression of Glut-1, further affects cells grow and proliferate. Meanwhile, studies have confirmed that transforming growth factor β 1 (TGF-β) induces Glut-1 expression and promotes aerobic glycolysis, thus participating in metabolic reprogramming of HSCs (Zhou et al., 2021). Hypoxia-Inducible Factor 1 alpha (HIF-1α) is a transcriptional active nuclear protein with broad target gene spectrum, and participate in the occurrence and development of liver diseases (Yuan et al., 2022). Studies has reported that the hedgehog signaling through HIF-1α can upregulate the activity of key glycolytic enzymes even under normoxic conditions, thereby enhancing glycolytic flux and promoting HSCs activation (She et al., 2018; Dong et al., 2022). HIF-1α also enhances aerobic glycolytic flux by promoting the expression of glucose transporter proteins. This effect is mediated through the binding of HIF-1 to hypoxia-responsive elements located in the promoter regions of the corresponding genes (Kierans and Taylor., 2021). In addition, knockdown of Glut-1 also can affect HIF-1α expression has been demonstrated in Hep-2 laryngeal carcinoma cells (Jiang et al., 2018). Here, we investigated the effects of Glut-1 and HIF-1α on hepatic fibrosis by regulating glycolysis in hepatic microenvironment.

Trigonelline (TRG, chemical structure listed in Fig. 1A) is a plant alkaloid first isolated from Trigonella foenum-graecum L, and is widely present in various edible natural products for human daily consumption, such as coffee beans (Nguyen et al., 2024). Previous studies have shown that TRG as a component of coffee and coffee by-products appears to be safe for human health (Konstantinidis et al., 2023). Over the past few decades, extensive researches on TRG have demonstrated its therapeutic effects in various pathological conditions, including diabetes, hyperlipidemia, migraine, and neuroprotective effects (Liang et al., 2023). Regarding liver diseases, study has reported that TRG could prevent liver lipid accumulation and lipid toxicity in mice induced by a high cholesterol and high fat diet by restoring liver autophagy (Sharma et al., 2018). Meanwhile, TRG protected nonalcoholic fatty liver disease in mice by regulating Bcl-2 and BAX expressions (Zhang et al., 2015). These studies have evaluated the effectiveness of TRG for liver protection, but there is a lack of data on its effectiveness in treating liver fibrosis.

Thus, the current study would investigate the anti-hepatic fibrosis effect of TRG and its potential mechanism in vivo and in vitro, especially based on perspective of glycolysis and energy metabolism. In addition, the study also discussed the potential mechanism of TRG against liver fibrosis by affecting the crosstalk between macrophages and HSCs.