Schisantherin A alleviates non-alcoholic fatty liver disease by restoring intestinal barrier function

Schisandra chinensis lignans ameliorate hepatic inflammation and steatosis in methionine choline-deficient diet-fed mice by modulating the gut-liver axis

ETHNOPHARMACOLOGICAL RELEVANCE

Schisandra chinensis is used as a traditional Chinese medicine to treat a variety of diseases. Schisandra chinensis lignans (SCL) are one of the most active components extracted from Schisandrae chinensis fructus, exhibit a broad array of pharmacological properties, especially anti-inflammatory and hepatic lipid-lowering effects, suggesting SCL may have potential anti-nonalcoholic steatohepatitis (NASH) ability. However, the therapeutic efficacy of SCL against NASH and the underlying mechanism of this action remains unclear.

AIM OF THE STUDY

In the current study, we aimed to investigate the anti-NASH action of SCL and explore the underlying mechanism in vitro and in vivo. We also assess the involvement of the gut-liver axis in the anti-NASH effects of SCL.

METHODS

Palmitic acid (PA)-treated HepG2 cells, mouse primary hepatocytes (MPHs) and methionine-choline deficient (MCD) diet-fed mice were selected as NASH models. ORO staining and qRT-PCR were performed to assess hepatic steatosis and inflammatory responses, respectively. Masson's trichrome staining was used to detect the liver fibrosis. Protein expression was detected by Western blotting or immunohistochemistry. The changes of gut microbiota were analyzed using 16S rDNA sequencing in mice. The levels of metabolites in liver and feces were measured by metabolomics.

RESULTS

The results showed that SCL treatment alleviated steatosis and inflammation in palmitic acid (PA)-treated HepG2 cells and mouse primary hepatocytes (MPHs). SCL treatment suppressed the phosphorylation of key components involved in NF-κB signaling and enhanced the expression of fatty acid oxidation (FAO)-related enzymes (e.g. CPT1, HMGCS2, and ACOX1) in PA-treated HepG2 cells. SCL could ameliorate hepatic steatosis and inflammation in NASH mice. SCL also ameliorated intestinal barrier injury and restructured the gut microbiota in NASH mice. SCL also modulated hepatic and colonic bile acid metabolism via FXR signaling.

CONCLUSION

These findings indicate that SCL treatment ameliorates hepatic inflammation and steatosis in NASH mice, potentially though to the suppression of NF-κB signaling and the promotion of fatty acid β-oxidation. Moreover, SCL could restore gut microbiota-mediated bile acid homeostasis via activation of FXR/FGF15 signaling. Our study presents a pharmacological rationale for using SCL in the management of NASH.

Health benefits of medicinal plant natural products via microbiota-mediated different gut axes

This review examines the multifaceted roles of medicinal plant natural products in influencing gut microbiota and their subsequent impact on various organ systems through established gut axes, including the gut-brain, gut-liver, gut-heart, gut-lung, and gut-kidney axes. Medicinal plant natural products have exhibited diverse pharmacological activities, including modulation of microbiota composition, enhancement of metabolic processes, and alleviation of inflammation and oxidative stress. Evidence suggests that these components can ameliorate conditions such as neurological disorders, metabolic syndrome, and chronic kidney disease by restoring microbial balance and improving gut barrier integrity. Furthermore, the review highlights the potential of medicinal plant natural products to foster beneficial microbial communities and improve gut health, which may lead to reduced disease severity and inflammation. By comprehensively analyzing current literature, this review provides a foundation for future research aim at exploring the therapeutic applications of medicinal plant natural products in disease prevention and treatment. The findings underscore the need for further studies to elucidate the underlying mechanisms of action and validate the clinical efficacy of medicinal plant natural products in managing chronic conditions through gut microbiota modulation.

Heat-Processed Diet Rich in Advanced Glycation End Products Induced the Onset and Progression of NAFLD via Disrupting Gut Homeostasis and Hepatic Lipid Metabolism

Epidemiologic studies have suggested an association between the consumption of dietary advanced glycation end products (dAGEs) and the incidence of nonalcoholic fatty liver disease (NAFLD). However, the precise mechanism by which dAGEs induce NAFLD development, particularly the pathogenic role of the gut-liver axis, remains poorly understood. In this study, by establishing a high-AGE diet (HAD)-fed C57BL/6 mouse model, we employed multiomics approaches combined with a series of biological analyses to investigate the effect of HAD on NAFLD in vivo. Our results showed that exposure to HAD led to fat accumulation, oxidative stress, inflammation, and fibrosis in the liver of mice. Transcriptome analysis further revealed that HAD exposure disrupted lipid metabolism and activated inflammation-related signaling pathways in the liver. Additionally, exposure to HAD induced perturbations in gut homeostasis, as evidenced by the compromised gut barrier function, reduced probiotic abundance, and increases in pathogenic bacterial proportions. Dysbiosis of gut homeostasis may further act as a trigger for the initiation and progression of NAFLD via the gut-liver axis. This study sheds light on the underlying mechanisms through which dAGEs contribute to the development of NAFLD and helps to understand the detrimental effects of food ultraprocessing products in modern diets. Future studies are needed to explore the in-depth mechanisms related to the gut-liver axis to consolidate our conclusions.

Anti-pneumoconiosis effect of schisantherin A in PMA-induced A549 cells and SiO2/TiO2nanoparticles-induced acute pulmonary injury in mice

There has been significant global interest in respiratory health driven by the coronavirus disease (COVID-19) and severe environmental pollution. This study explored the potential of schisantherin A (SchA), a compound derived from Schisandra chinensis, to protect against acute pneumoconiosis. We assessed the effects of SchA on phorbol 12-myristate 13-acetate (PMA)-stimulated A549 alveolar epithelial cells and SiO2/TiO2-induced pulmonary injury in mice. In A549 cells, SchA significantly decreased pro-inflammatory mediators such as inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), and interleukin (IL)-8 levels. SchA-mediated reduction in inflammatory mediators was associated with the downregulation of PMA-stimulated nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and mitogen-activated protein kinase (MAPK) signaling activation. In SiO2/TiO2-induced lung-injured mice, SchA administration significantly reduced MUC5AC production in lung tissue. SchA administration significantly downregulated the overexpression of NK-κB and the subsequent production of COX-2, iNOS, and NOD-like receptor pyrin domain-containing protein 3 (NLRP3) inflammasomes. It significantly suppressed expected increases in total cell numbers and pro-inflammatory cytokines, including tumor necrosis factor-alpha (TNF-α) and IL-1β in the bronchoalveolar lavage fluid (BALF) in SiO2/TiO2-stimulated mice. In contrast, the SiO2/TiO2-mediated decrease in IL-10 levels was significantly improved by SchA treatment. These fundamental results can be used to develop potential treatments involving SchA for acute pneumoconiosis.

Modulatory effects of traditional Chinese medicines on gut microbiota and the microbiota-gut-x axis

The gut microbiota offers numerous benefits to the human body, including the promotion of nutrient absorption, participation in metabolic processes, and enhancement of immune function. Recent studies have introduced the concept of the gut-organ axis, which encompasses interactions such as the gut-brain axis, gut-liver axis, and gut-lung axis. This concept underscores the complex interplay between gut microbiota and various organs and tissues, including the brain, heart, lungs, liver, kidneys, muscles, and bones. Growing evidence indicates that gut microbiota can influence the onset and progression of multi-organ system diseases through their effects on the gut-organ axis. Traditional Chinese medicine has demonstrated significant efficacy in regulating the gastrointestinal system, leveraging its unique advantages. Considerable advancements have been made in understanding the role of gut microbiota and the gut-organ axis within the mechanisms of action of traditional Chinese medicine. This review aims to elucidate the roles of gut microbiota and the gut-organ axis in human health, explore the potential connections between traditional Chinese medicine and gut microbiota, and examine the therapeutic effects of traditional Chinese medicine on the microbiota-gut-organ axis. Furthermore, the review addresses the limitations and challenges present in current research while proposing potential directions for future investigations in this area.

Effects of plant natural products on metabolic-associated fatty liver disease and the underlying mechanisms: a narrative review with a focus on the modulation of the gut microbiota

Metabolic-associated fatty liver disease (MAFLD) is a chronic liver disease characterized by the excessive accumulation of fat in hepatocytes. However, due to the complex pathogenesis of MAFLD, there are no officially approved drugs for treatment. Therefore, there is an urgent need to find safe and effective anti-MAFLD drugs. Recently, the relationship between the gut microbiota and MAFLD has been widely recognized, and treating MAFLD by regulating the gut microbiota may be a new therapeutic strategy. Natural products, especially plant natural products, have attracted much attention in the treatment of MAFLD due to their multiple targets and pathways and few side effects. Moreover, the structure and function of the gut microbiota can be influenced by exposure to plant natural products. However, the effects of plant natural products on MAFLD through targeting of the gut microbiota and the underlying mechanisms are poorly understood. Based on the above information and to address the potential therapeutic role of plant natural products in MAFLD, we systematically summarize the effects and mechanisms of action of plant natural products in the prevention and treatment of MAFLD through targeting of the gut microbiota. This narrative review provides feasible ideas for further exploration of safer and more effective natural drugs for the prevention and treatment of MAFLD.

Schisantherin A protects hepatocyte via upregulating DDAH1 to ameliorate liver fibrosis in mice

BACKGROUND

Hepatic fibrosis is the pivotal determinant in the progression of chronic liver diseases towards cirrhosis or advanced stages. Studies have shown that Schisantherin A (Sin A), the primary active compound from Schizandra chinensis (Turcz.) Baill., exhibits anti-hepatic fibrosis effects. However, the mechanism of Sin A in liver fibrosis remain unclear.

PURPOSE

To examine the effects and underlying mechanism of Sin A on hepatic fibrosis.

STUDY DESIGN AND METHODS

The effects and mechanism of Sin A were investigated using liver fibrosis mouse models induced by carbon tetrachloride (CCl4) or dimethylnitrosamine (DMN), as well as H2O2-induced hepatocyte injury in vitro.

RESULTS

Sin A treatment ameliorated hepatocyte injury, inflammation, hepatic sinusoidal capillarization, and hepatic fibrosis in both CCl4-induced and DMN-induced mice. Sin A effectively reversed the reduction of DDAH1 expression, the p-eNOS/eNOS ratio and NO generation and attenuated the elevation of hepatic ADMA level induced by CCl4 and DMN. Knockdown of DDAH1 in hepatocytes not only triggered hepatocyte damage, but it also counteracted the effect of Sin A on protecting hepatocytes in vitro.

CONCLUSION

Our findings indicate that Sin A ameliorates liver fibrosis by upregulating DDAH1 to protect against hepatocyte injury. These results provide compelling evidence for Sin A treatment in liver fibrosis.

Mechanisms and Therapeutic Strategies for MAFLD Targeting TLR4 Signaling Pathways

BACKGROUND

Metabolic-associated fatty liver disease (MAFLD) is one of the most common chronic liver diseases. The underlying pathophysiological mechanisms are intricate and involve various factors. Unfortunately, there is currently a lack of available effective treatment options. Toll-like receptors (TLRs) are a group of pattern-recognition receptors that are responsible for activating the innate immune system. Research has demonstrated that TLR4 plays a pivotal role in the progression of MAFLD by facilitating the pathophysiological mechanisms.

SUMMARY

Lipid peroxidation, pro-inflammatory factors, insulin resistance (IR), and dysbiosis of intestinal microbiota are considered as the pathogenic mechanisms of MAFLD. This review summarizes the impact of TLR4 signaling pathways on the progression of MAFLD, specifically in relation to lipid metabolic disorders, IR, oxidative stress, and gut microbiota disorders. Additionally, we emphasize the potential therapeutic approaches for MAFLD that target TLR4 signaling pathways, including the use of plant extracts, traditional Chinese medicines, probiotics, pharmaceuticals such as peroxisome proliferator-activated receptor antagonists and farnesol X agonists, and lifestyle modifications such as dietary changes and exercise also considered. Furthermore, TLR4 signaling pathways have also been linked to the lean MAFLD.

KEY MESSAGES

TLR4 plays a crucial role in MAFLD by triggering IR, buildup of lipids, imbalance in gut microbiota, oxidative stress, and initiation of immune responses. The mitigation of MAFLD can be accomplished by suppressing the TLR4 signaling pathway. In the future, it could potentially emerge as a therapeutic target for the condition.

Neurodegenerative and Neurodevelopmental Diseases and the Gut-Brain Axis: The Potential of Therapeutic Targeting of the Microbiome

The human gut microbiome contains the largest number of bacteria in the body and has the potential to greatly influence metabolism, not only locally but also systemically. There is an established link between a healthy, balanced, and diverse microbiome and overall health. When the gut microbiome becomes unbalanced (dysbiosis) through dietary changes, medication use, lifestyle choices, environmental factors, and ageing, this has a profound effect on our health and is linked to many diseases, including lifestyle diseases, metabolic diseases, inflammatory diseases, and neurological diseases. While this link in humans is largely an association of dysbiosis with disease, in animal models, a causative link can be demonstrated. The link between the gut and the brain is particularly important in maintaining brain health, with a strong association between dysbiosis in the gut and neurodegenerative and neurodevelopmental diseases. This link suggests not only that the gut microbiota composition can be used to make an early diagnosis of neurodegenerative and neurodevelopmental diseases but also that modifying the gut microbiome to influence the microbiome-gut-brain axis might present a therapeutic target for diseases that have proved intractable, with the aim of altering the trajectory of neurodegenerative and neurodevelopmental diseases such as Alzheimer's disease, Parkinson's disease, multiple sclerosis, autism spectrum disorder, and attention-deficit hyperactivity disorder, among others. There is also a microbiome-gut-brain link to other potentially reversible neurological diseases, such as migraine, post-operative cognitive dysfunction, and long COVID, which might be considered models of therapy for neurodegenerative disease. The role of traditional methods in altering the microbiome, as well as newer, more novel treatments such as faecal microbiome transplants and photobiomodulation, are discussed.

Gut dysbiosis in nonalcoholic fatty liver disease: pathogenesis, diagnosis, and therapeutic implications

The incidence of nonalcoholic fatty liver disease (NAFLD) is increasing recently and has become one of the most common clinical liver diseases. Since the pathogenesis of NAFLD has not been completely elucidated, few effective therapeutic drugs are available. As the "second genome" of human body, gut microbiota plays an important role in the digestion, absorption and metabolism of food and drugs. Gut microbiota can act as an important driver to advance the occurrence and development of NAFLD, and to accelerate its progression to cirrhosis and hepatocellular carcinoma. Growing evidence has demonstrated that gut microbiota and its metabolites directly affect intestinal morphology and immune response, resulting in the abnormal activation of inflammation and intestinal endotoxemia; gut dysbiosis also causes dysfunction of gut-liver axis via alteration of bile acid metabolism pathway. Because of its composition diversity and disease-specific expression characteristics, gut microbiota holds strong promise as novel biomarkers and therapeutic targets for NAFLD. Intervening intestinal microbiota, such as antibiotic/probiotic treatment and fecal transplantation, has been a novel strategy for preventing and treating NAFLD. In this article, we have reviewed the emerging functions and association of gut bacterial components in different stages of NAFLD progression and discussed its potential implications in NAFLD diagnosis and therapy.