Efficacy and mechanism of Xing-Pi-Qing-Gan decoction in treating alcoholic liver disease

Abstract

Alcoholic liver disease (ALD) represents a significant global health burden driven by oxidative stress, metabolic dysregulation, and chronic inflammation, yet effective therapies targeting its complex pathogenesis are limited. This study elucidates that Xing-Pi-Qing-Gan decoction (XPQG) significantly mitigates ethanol-induced liver injury and steatosis. Importantly, the authors identify the suppression of DDIT3 and the restoration of nuclear factor erythroid 2-related factor 2/heme oxygenase-1 signaling as the key molecular mechanism. These findings suggest that XPQG is a promising therapeutic candidate for ALD. In addition to confirming these findings, this review critically examines the potential effects of XPQG on the “gut-liver axis” regulation and epigenetic mechanisms, including microRNA-mediated post-transcriptional control, while emphasizing the necessity of standardized quality control based on quality markers for future clinical applications.

Key Words: Alcoholic liver disease; Xing-Pi-Qing-Gan decoction; DNA damage-inducible transcript 3; Nuclear factor erythroid 2-related factor 2/heme oxygenase-1 signaling pathway; Oxidative stress; Gut-liver axis; Epigenetics

Core Tip: This review on Xing-Pi-Qing-Gan decoction (XPQG) for alcoholic liver disease, demonstrating the mechanism by which XPQG inhibits liver injury by inhibiting DNA damage-inducible transcript 3 and activating nuclear factor erythroid 2-related factor 2/heme oxygenase-1 through multiple sets of experiments. On the basis of affirming the scientific evidence of traditional Chinese medicine in the treatment of metabolic liver disease, this article discusses the potential regulation mechanism of the “gut-liver axis” of this prescription, explores the epigenetic regulatory network involving non-coding RNAs, and puts forward the necessity of establishing a standardized drug quality control system incorporating chemical fingerprinting and pharmacokinetic profiling in the future clinical transformation.

INTRODUCTION

Huang et al[1] systematically elucidated the potential mechanism of Xing-Pi-Qing-Gan decoction (XPQG) in the treatment of alcoholic liver disease (ALD) through integrative multi-omics analyses, and attributed its therapeutic effects to downregulation of DDIT3 and restoration of the nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) antioxidant signaling pathway. These findings thereby provide robust molecular evidence supporting the application of traditional Chinese medicine (TCM) in the management of complex metabolic liver disorders. We fully concur with these conclusions. The results are in line with the general trend that multi-component herbal drugs can target multiple pathological nodes at once, yielding the potential advantage over single-target synthetic drugs[2,3]. In this article, we aim to further discuss and expand upon the clinical significance and underlying mechanisms in this study.

ALD

ALD continues to represent one of the leading causes of cirrhosis and liver-related mortality worldwide[4]. The global burden of ALD has been escalating, with alcohol consumption accounting for approximately 5% of the global burden of disease and injury[5,6]. Although alcohol abstinence remains the cornerstone of treatment, therapeutic options currently available in clinical practice for patients with advanced disease or suboptimal adherence are limited. Corticosteroids and pentoxifylline, despite their widespread clinical use, show limited efficacy in improving long-term survival and are associated with a range of adverse effects[7]. Recent clinical guidelines emphasize the need for novel pharmacological interventions that can halt disease progression in severe alcoholic hepatitis[3,8]. Therefore, there is an urgent need to identify alternative therapeutic strategies that are both safe and effective and capable of intervening in the pathogenic progression of ALD. The study by Huang et al[1] not only demonstrated that XPQG significantly ameliorated the pathological features of liver steatosis and injury, but more importantly, employed integrative multi-omics approaches to bridge the gap between traditional herbal formulations and contemporary molecular medicine, a contribution of substantial significance for advancing the modernization and global recognition of traditional Chinese medicine.

Firstly, the study centered on elucidating the role of DDIT3 (also known as C/EBP homologous protein, CHOP) in the cellular response to XPQG. DDIT3 is a key mediator of endoplasmic reticulum (ER) stress-mediated apoptosis and is closely associated with hepatocyte cell death during the progression of ALD[9]. ER stress is triggered by the accumulation of unfolded proteins, activating three sensor proteins PERK, IRE1 and ATF6[10,11]. The authors found that XPQG could markedly attenuate ethanol-induced overexpression of DDIT3, thereby providing mechanistic insight into how TCM compounds protect the liver by alleviating organelle stress. Recent studies have demonstrated that genetic depletion of DDIT3/CHOP significantly attenuates ER stress and ameliorates hepatic steatosis in mouse models, thereby reinforcing its critical role as a potential therapeutic target[12]. DDIT3 promotes apoptosis by downregulating Bcl-2, and upregulating pro-apoptotic proteins (e.g., Bim and PUMA) which will result in membrane permeabilization in mitochondrial outer membrane[13,14]. In the context of ALD, DDIT3 has been further validated as a central molecular node that orchestrates disease progression: It promotes hepatocyte apoptosis through activation of the BAX/Bcl-2 signaling axis while concurrently impairing Nrf2-dependent antioxidant responses. Moreover, emerging evidence suggests that modulation of oxidative stress through herbal plant-derived compounds, as well as the potential regulatory roles of epigenetic modifications-such as DNA methylation and microRNAs-in controlling DDIT3 expression, have emerged as promising new research areas worthy of deeper investigation[15,16]. In particular, ethanol exposure may promote DDIT3 transcription by increasing histone H3K9 acetylation at its promoter region via histone acetyltransferase[17,18]. However, the pathogenesis of ALD is highly complex and multifactorial, with a pivotal contribution arising from chronic alcohol-induced gut microbiota dysbiosis and disruption of intestinal barrier integrity. This pathological state results in intestinal hyperpermeability (leaky gut syndrome), allowing gut-derived endotoxins such as lipopolysaccharide to enter the liver via the portal circulation. Ethanol metabolism by cytochrome P450 2E1 generates reactive oxygen species (ROS) that further damage the intestinal epithelium[19-21]. Subsequent activation of toll-like receptor 4 on Kupffer cells amplifies inflammatory signaling cascades and further exacerbates hepatic oxidative stress and tissue injury[22,23]. The release of pro-inflammatory cytokines, including tumor necrosis factor-alpha, interleukin-1 beta, and interleukin-6, creates a vicious cycle of inflammation and hepatocellular damage[24,25]. Following oral administration, numerous bioactive constituents within traditional Chinese medicine decoctions undergo extensive biotransformation by the gut microbiota. These microbiota-mediated metabolic processes critically shape their systemic bioavailability and pharmacodynamic properties through the microbiota-gut-organ axis[26]. Specific bacterial genera, such as Akkermansia and Faecalibacterium, have been shown to correlate with improved barrier function and reduced endotoxemia in ALD models[27,28]. Future studies should further investigate whether XPQG acts upstream to prevent the initiation of ER stress and oxidative stress by modulating the composition of the gut microbiota or strengthening intestinal barrier integrity through the upregulation of tight junction proteins like zonula occludens-1 and occludin[29,30].

Secondly, the restoration of the Nrf2/HO-1 signaling pathway represents a well-established target for antioxidant therapy and a central strategy in the development and clinical translation of antioxidant drugs[31,32]. Under basal conditions, Nrf2 is sequestered in the cytoplasm by Keap1, which targets it for ubiquitination and degradation[33,34]. Traditional Chinese medicine compounds are typically multi-component and multi-target in nature[35]. Electrophilic compounds in herbs can modify cysteine residues on Keap1, leading to Nrf2 stabilization and nuclear translocation[36,37]. In addition to directly modulating Nrf2 nuclear translocation, whether the bioactive constituents of XPQG (such as flavonoids or saponins) regulate the expression of Nrf2 or DDIT3 through epigenetic mechanisms, including microRNA or DNA methylation, remains a scientific question to be addressed. Accumulating evidence indicates that alcohol exposure profoundly alters the expression of specific miRNAs. Among these, miR-34a is markedly upregulated in normal human hepatocytes and cholangiocytes following combined ethanol and lipopolysaccharide stimulation, while overexpression of miR-34a reduces ethanol-induced apoptosis in both cell types. After demethylation treatment, the expression levels of miR-34a significantly increased in both cell types[38]. Other miRNAs, such as miR-155 and miR-21, have also been implicated in regulating inflammatory responses and fibrosis in ALD[39,40]. In addition, miR-125b-5p has been shown to modulate the Keap1 (Kelch-like ECH-associated protein 1)/Nrf2/HO-1 antioxidant signaling pathway, thereby conferring protection against acute liver failure. These findings suggest that XPQG may exert its therapeutic effects through a similar epigenetic regulatory network[41]. Long non-coding RNAs and circular RNAs also serve as competing endogenous RNAs that sponge miRNAs, adding another layer of complexity to this regulatory network[42,43]. Furthermore, given that patients with ALD frequently exhibit mitochondrial dysfunction, investigation of the effects of XPQG on mitophagy may help to further elucidate the cytoprotective mechanisms underlying its anti-injury effects[44,45]. Impaired mitophagy leads to the accumulation of damaged mitochondria, which are major sources of ROS, further exacerbating oxidative stress[46,47]. To facilitate a clearer understanding of these complex interactions, we present a schematic illustration (Figure 1) and a summary of key pathways (Table 1) depicting the proposed mechanisms by which XPQG modulates the DDIT3-centered signaling network, restores Nrf2/HO-1 redox homeostasis, modulates gut microbiota composition, and ultimately attenuates hepatic injury.

Figure 1 Proposed molecular mechanism underlying the therapeutic effects of Xing-Pi-Qing-Gan decoction in alcoholic liver disease. BAX: Bcl-2-associated X protein; MAPK: Mitogen-activated protein kinase; ROS: Reactive oxygen species; SREBP-1c: Sterol regulatory element-binding protein-1c; Nrf2: Nuclear factor erythroid 2-related factor 2; HO-1: Heme oxygenase-1; XPQG: Xing-Pi-Qing-Gan decoction.

Table 1 Summary of key molecular pathways in alcoholic liver disease.

Pathway	Key molecules	Role in ALD pathogenesis	Ref.
ER stress	DDIT3, PERK, IRE1, ATF6	Mediates hepatocyte apoptosis and steatosis	[9-14]
Oxidative stress	Nrf2, HO-1, Keap1	Drives oxidative damage and inflammation	[31-34,36,37]
Inflammation	TNF-α, IL-1β, IL-6, TLR4	Amplifies immune response and tissue damage	[22-25]
Gut-liver axis	ZO-1, occludin	Disruption leads to endotoxemia	[26-28]
Epigenetics	miR-34a, miR-155, miR-21, miR-125b-5p	Regulates gene expression post-transcriptionally	[15,16,38,40-43]
Mitophagy	PINK1, Parkin	Clears damaged mitochondria	[44-47]

ATF6: Activating transcription factor 6; DDIT3: DNA damage-inducible transcript 3; HO-1: Heme oxygenase-1; IL-1β: Interleukin-1 beta; IL-6: Interleukin-6; IRE1: Inositol-requiring enzyme 1; Keap1: Kelch-like ECH-associated protein 1; Nrf2: Nuclear factor erythroid 2-related factor 2; PERK: Protein kinase RNA-like endoplasmic reticulum kinase; TLR4: Toll-like receptor 4; TNF-α: Tumor necrosis factor-alpha; ZO-1: Zonula occludens-1.

Finally, it must be acknowledged that the consistency and quality control of traditional Chinese medicine compounds remain critical challenges, both at the level of basic research and during clinical translation. Although the chemical composition of XPQG is clearly characterized in the present study, in real-world clinical practice, the therapeutic stability may be affected by batch-to-batch variability in the content of active ingredients derived from herbal materials[48,49]. Changes in soil, climate, harvesting time, and processing could alter the phytochemical profile of herbal medicine[50,51]. Therefore, the quality control regime can be provided by chemical fingerprinting, such as high-performance liquid chromatography and liquid chromatography-mass spectrometry[52,53], and to rigorously monitor the pharmacokinetic characteristics of the formulation in future clinical trials. We have suggested “Q-Marker” (Quality Marker) to detect compounds in the realm of clinical efficacy and safety[54,55]. These measures will provide essential evidence-based support for the development and validation of XPQG as a therapeutic option for ALD. Good Agricultural Practice (GAP) requirements can also be implemented[56,57].

CHALLENGES OF TRADITIONAL CHINESE MEDICINE

Although research on traditional Chinese medicine is increasingly recognized as feasible and promising, substantial challenges remain, including the need for standardized formulations, clearer elucidation of systematic mechanisms of action-often referred to as the “black box”-and rigorous clinical validation. The complexity of herb-drug interactions should also be addressed, especially for patients taking combined drugs for comorbidities[58,59]. Moving forward, system biology and various “omics” approaches should be leveraged to elucidate the synergistic effects of complex multi-component formulas like XPQG, thereby establishing a robust, evidence-based framework for clinical translation[60]. Large-scale, multi-center randomized controlled trials are ultimately needed to verify the efficacy and stability of XPQG in a clinical setting.

CONCLUSION

In summary, Huang et al[1] identified XPQG as a promising candidate traditional Chinese medicine for the treatment of ALD and elucidated its underlying molecular mechanism. We anticipate further studies and publications addressing the regulatory effects of XPQG on the gut-liver axis, epigenetic modifications, and mitochondrial quality control, as well as comprehensive evaluations of its efficacy and safety in large-scale clinical cohorts. Integrating modern systems biology and traditional medical knowledge is key to unlocking the full potential of XPQG for human liver health.