Novel Therapeutic Approaches to Liver Fibrosis Based on Targeting Oxidative Stress

Mechanism-guided drug development and treatment for liver fibrosis: a clinical perspective

Liver fibrosis is a common response to chronic liver injury due to multiple etiologies and plays a crucial in the progression of chronic liver disease to cirrhosis, hepatocellular carcinoma, and other liver-related clinical outcomes. Currently, available treatments to block liver fibrosis are designed to eliminate the underlying causes of liver disease. The lack of truly effective drugs to regress or reverse fibrosis is a major unmet clinical need. In this context, this article briefly describes the pathological process of hepatic fibrosis and focuses on reviewing the progress of clinical studies on mechanism-based anti-fibrotic drug development and therapy, highlighting that the positive effect of thyroid hormone receptor-β (THR-β) analogs, fibroblast growth factor 21 (FGF21) analogues, Glucagon-like peptide 1 receptor (GLP-1R) agonists, pan-peroxisome proliferator-activated receptor (pan-PPAR) agonists, fatty acid synthase (FASN) inhibitors, and hydronidone in reducing liver fibrosis caused by specific etiologies. Moreover, multi-pathway guided combination therapy or traditional Chinese medicine demonstrate significant advantages in combating liver fibrosis. Finally, new technologies and approaches affecting the clinical development of anti-hepatic fibrosis drugs were discussed.

Dual-Color Visualization of Hepatic Fibrosis and Multidimensional Assessment of Therapeutic Drugs by a Multifunctional Single-Molecular Fluorescent Probe

There is a high relevance between changes in ClO- levels/mitochondrial morphology and the development of hepatic fibrosis; however, the efficient tools that are capable of real-time monitoring both of them and exploring their interrelations are extremely rare. Herein, we developed a multifunctional fluorescent probe based on a "three-in-one" strategy, named Mito-XS, which is firmly anchored in mitochondria, allowing for the ratiometric detection of ClO- and the accurate analysis of mitochondrial morphology. Probe Mito-XS can sensitively capture the changes of ClO- levels in mitochondria and successfully achieve simultaneous real-time monitoring of ClO- levels and mitochondrial morphology during oxidative stress. Utilizing probe Mito-XS, the evaluations of three therapeutic drugs (silymarin, methyl ferulic acid, and puerarin) on protecting cells from CCl4-induced damage were visualized by assessing their capabilities of inhibiting ClO- levels and maintaining mitochondrial morphology. Furthermore, dual-color imaging in hepatic fibrosis mice models revealed the exacerbation of hepatic fibrosis, and the therapeutic effect of puerarin can be tracked by the fluctuation of ClO- levels. Therefore, probe Mito-XS is an effective imaging tool to monitor mitochondrial morphology and ClO- levels at the same time and has the potential to work as an evaluation tool to screen therapeutic drugs for hepatic fibrosis treatment.

A comprehensive study of liver-gut microbiota and antioxidant enzyme activity mediated regulation of late-laying hens by high and low residual feed intake

Residual feed intake (RFI) is a better indicator of feed efficiency than feed conversion ratio (FCR). It is frequently used to evaluate the efficacy of poultry and livestock feed consumption. Generally, Low RFI (LRFI) is associated with better feed conversion efficiency, whereas high RFI (HRFI) suggests poorer feed conversion efficiency. The study examined the association between microorganisms, tissue and organ functions. The results demonstrated that in contrast to the HRFI group, the LRFI group revealed higher length measurements, the digestive organs' mass, and chest width. The antioxidant indices revealed that the enzymatic activities (catalase and glutathione peroxidase) in the LRFI group were significantly higher than those in the HRFI group. The serum levels of HDLC, AST, and ACTH were identified as potential markers that could affect RFI. The variations between high and low RFI and the function of the liver and cecum microbiota of hens during late laying period were systematically investigated by multiple omics techniques. Through 16S, the most common beneficial microbial population in the gut of LRFI groups, such as Oscillospirales, Ruminococcaceae, and Butyricicoccaceae, has been detected via a microbiome-metabolome association analysis. Through multi-omics analysis, we found that FABP1 and ACSS2 are important regulatory genes affecting RFI. These findings will provide a basis for comprehending the role of gut microbiota in regulating RFI and the molecular mechanism behind the phenotypic changes observed in late-laying hens.

α‑1 Antitrypsin is a potential target of inflammation and immunomodulation (Review)

α‑1 Antitrypsin (AAT) is an acute phase protein encoded by the serine protease inhibitor family A member 1 gene. This multifunctional protein serves several roles, including anti‑inflammatory, antibacterial, antiapoptotic and immune regulatory functions. The primary role of AAT is to protect tissues and organs from protease‑induced damage due to its function as a serine protease inhibitor. AAT is associated with the development of lung inflammation, liver inflammation and immune‑mediated inflammatory diseases, which are influenced by environmental and genetic factors. For instance, AAT acts as an anti‑inflammatory protein to prevent and reverse type I diabetes. The present study briefly reviewed the molecular properties and mechanisms of AAT, as well as advances in the study of lung, liver and inflammatory diseases associated with AAT. The potential of AAT as a diagnostic and therapeutic target for inflammatory and immune‑mediated inflammatory diseases was reviewed. In addition, the damaging and protective effects of AAT, and its effects on organ function were discussed.

ROS-responsive injectable hydrogels loaded with exosomes carrying miR-4500 reverse liver fibrosis

The reversal of liver fibrosis requires effective strategies to reduce oxidative stress and inhibition of hepatic stellate cell (HSC) activation. MiR-4500 regulates pathological angiogenesis and collagen mRNA stability, with the potential to inhibit fibrosis. Herein, we explored the inhibition of HSC activation in vitro by exosomes (Exos) carrying miR-4500 and encapsulated ExosmiR-4500 in an intelligent injectable hydrogel with biological activity and reactive oxygen species (ROS) responsiveness for application in oxidative stress environments. Briefly, reversible boronic ester bonds were integrated into gelatin-based hydrogels through dynamic crosslinking of quaternized chitosan (QCS) and 4-carboxyphenylboronic acid (CPBA)-modified gelatin. The QCS-CPBA-Gelatin (QCG) hydrogel scavenged excess ROS from the local microenvironment and released ExosmiR-4500 through the dissociation of boronic ester bonds, providing a favorable microenvironment and in situ sustained-release drug delivery system for ExosmiR-4500. The results showed that QCG@ExosmiR-4500 hydrogel has biocompatibility, biodegradability, and slow-release ability, which could effectively clear ROS and inhibit HSC activation and pathological angiogenesis in vitro and in vivo. Furthermore, transcriptome analysis suggests that the pharmacological mechanism of the QCG@ExosmiR-4500 hydrogel is mainly related to anti-oxidation, anti-angiogenesis, anti-fibrosis processes, and signaling pathways. Thus, our study demonstrates that an intelligently responsive ExosmiR-4500 delivery system based on injectable hydrogels is a promising strategy for the treatment of liver fibrosis.

Investigating the protective effects of luteolin and gallic acid from Luffa acutangulavar. amara (Roxb.) C. B. Clarke. Fruit pericarp against alcohol-induced liver toxicity: Extraction, bioactivity-guided fractionation, molecular docking, and dynamics studies

ETHNOPHARMACOLOGICAL RELEVANCE

Luffa acutangula var. amara (Roxb.) C.B. Clarke, known as 'Katu Koshataki' in Ayurveda, is a traditional medicinal plant in India. The juice of these fruits is recommended for chronic alcohol-induced liver diseases.

AIM OF THE STUDY

This study aimed to validate the hepatoprotective and antioxidant properties of Luffa acutangula var. amara fruit pericarp ethanolic extract (EOLA) against ethanol-induced chronic hepatotoxicity in rats, isolate bioactive phytochemicals and in silico evaluation.

MATERIALS AND METHODS

Ethanolic extract of L. acutangula var. amara fruit pericarp was evaluated in chronic alcohol-induced hepatitis (20% ethanol orally twice daily for 28 days) at doses of 100 and 200 mg/kg p.o. Additionally, in vivo anti-inflammatory and antioxidant potential were assessed. Luteolin and gallic acid were isolated using bioactivity guided fractionation. Furthermore, these phytochemicals were assessed for hepatoprotective potential using molecular docking and molecular dynamics studies against different targets.

RESULTS

The EOLA demonstrated efficacy in stabilizing elevated biochemical markers and antioxidant levels associated with ethanol-induced hepatotoxicity in rats, and it preserved the normal architecture of hepatocytes in histological analyses compared to the ethanol control group. The EOLA was subjected to fractionation using hexane: chloroform (8:2 → 2:8), followed by chloroform: methanol (8:2 → 2:8) to yield a total eight fractions. The fractions 1, 2, and 3 showed potent antioxidant potential, yielding luteolin and gallic acid as LAC-1 and LAC-3 from fractions 1 and 8, respectively. Gallic acid and luteolin were investigated using molecular docking and molecular dynamic simulation techniques to assess their interactions with key proteins such as Cytochrome P450 2C9, Superoxide Dismutase, Glutathione Peroxidase, Glutathione S-Transferase, Catalase, Peroxisome Proliferator-Activated Receptor-ϒ, Vanin-1, and Cannabinoid Receptor CB2. The metabolites exhibit strong binding stability, with a root mean square deviation range of less than 2.8 Å.

CONCLUSIONS

It can be concluded that the fruit pericarp of L. acutangula var. amara could be used as a functional food for reducing the liver damage caused by alcohol and other factors.

Liver fibrosis as a barometer of systemic health by gauging the risk of extrahepatic disease

This review article proposes the theory that liver fibrosis, the abnormal accumulation of excessive extracellular matrix, is not just an indicator of liver disease but also a negative reflection of overall systemic health. Liver fibrosis poses a heavy financial burden on healthcare systems worldwide and can develop due to chronic liver disease from various causes, often due to sustained inflammation. Liver fibrosis may not generate symptoms and become apparent only when it reaches the stage of cirrhosis and is associated with clinically significant portal hypertension and leads to decompensation events or promotes the development of hepatocellular carcinoma. While chronic viral hepatitis and excessive alcohol consumption were once the primary causes of chronic liver disease featuring fibrosis, this role is now increasingly taken over by metabolic dysfunction-associated steatotic liver disease (MASLD). In MASLD, endothelial dysfunction is an essential component in pathogenesis, promoting the development of liver fibrosis, but it is also present in endothelial cells of other organs such as the heart, lungs, and kidneys. Accordingly, liver fibrosis is a significant predictor of liver-related outcomes, as well as all-cause mortality, cardiovascular risk, and extrahepatic cancer. Physicians should be aware that individuals seeking medical attention for reasons unrelated to liver health may also have advanced fibrosis. Early identification of these at-risk individuals can lead to a more comprehensive assessment and the use of various treatment options, both approved and investigational, to slow or reverse the progression of liver fibrosis.

Ferroptosis promotes valproate-induced liver steatosis in vitro and in vivo

Valproic acid (VPA), a common antiepileptic drug, can cause liver steatosis after long-term therapy. However, an impact of ferroptosis on VPA-induced liver steatosis has not been investigated. In the study, treatment with VPA promoted ferroptosis in the livers of mice by elevating ferrous iron (Fe2+) levels derived from the increased absorption by transferrin receptor 1 (TFR1) and the decreased storage by ferritin (FTH1 and FTL), disrupting the redox balance via reduced levels of solute carrier family 7 member 11 (SLC7A11), glutathione (GSH), and glutathione peroxidase 4 (GPX4), and augmenting acyl-CoA synthetase long-chain family member 4 (ACSL4) -mediated lipid peroxide generation, accompanied by enhanced liver steatosis. All the changes were significantly reversed by co-treatment with an iron-chelating agent, deferoxamine mesylate (DFO) and a ferroptosis inhibitor, ferrostatin-1 (Fer-1). Similarly, the increases in Fe2+, TFR1, and ACSL4 levels, as well as the decreases in GSH, GPX4, and ferroportin (FPN) levels, were detected in VPA-treated HepG2 cells. These changes were also attenuated after co-treatment with Fer-1. It demonstrates that ferroptosis promotes VPA-induced liver steatosis through iron overload, inhibition of the GSH-GPX4 axis, and upregulation of ACSL4. It offers a potential therapy targeting ferroptosis for patients with liver steatosis following VPA treatment.

The antifibrotic potential of IMT504: modulation of GLAST + Wnt1 + bone marrow stromal progenitors and hepatic microenvironment

BACKGROUND

The immunomodulatory oligodeoxynucleotide (ODN) IMT504 might harbor antifibrotic properties within the liver.

METHODS

Fibrosis models were induced in mice through thioacetamide (TAA) administration and bile-duct ligation. Cre-loxP mice were utilized to identify GLAST + Wnt1 + bone marrow stromal progenitors (BMSPs) and to examine their contribution with cells in the liver. In vivo and in vitro assays; flow-cytometry, immunohistochemistry, and qPCR were conducted.

RESULTS

IMT504 demonstrated significant inhibition of liver fibrogenesis progression and reversal of established fibrosis. Early responses to IMT504 involved the suppression of profibrogenic and proinflammatory markers, coupled with an augmentation of hepatocyte proliferation. Additionally, this ODN stimulated the proliferation and mobilization of GLAST + Wnt1 + BMSPs, likely amplifying their contribution with endothelial- and hepatocytes-like cells. Moreover, IMT504 significantly modulated the expression levels of Wnt ligands and signaling pathway/target genes specifically within GLAST + Wnt1 + BMSPs, with minimal impact on other BMSPs. Intriguingly, both IMT504 and conditioned media from IMT504-pre-treated GLAST + Wnt1 + BMSPs shifted the phenotype of fibrotic macrophages, hepatic stellate cells, and hepatocytes, consistent with the potent antifibrotic effects observed.

CONCLUSION

In summary, our findings identify IMT504 as a promising candidate molecule with potent antifibrotic properties, operating through both direct and indirect mechanisms, including the activation of GLAST + Wnt1 + BMSPs.

Forsythiaside-A improved bile-duct-ligation-induced liver fibrosis in mice: The involvement of alleviating mitochondrial damage and ferroptosis in hepatocytes via activating Nrf2

Liver fibrosis is a key and reversible stage in the progression of many chronic liver diseases to cirrhosis or hepatocellular carcinoma. Forsythiaside-A (FTA), a main compound isolated from Forsythiae Fructus, has an excellent liver protective activity. This study aims to investigate the efficacy of FTA in improving cholestatic liver fibrosis. Bile-duct-ligation (BDL) was conducted to induce liver fibrosis in mice. Hepatic collagen deposition was evaluated by Masson and Sirus red staining. The bile acid spectrum in the liver and serum was analyzed by mass spectrometry. Liver oxidative stress injury and mitochondria damage were observed by using Mito-Tracker Red fluorescence staining, transmission electron microscopy, etc. The level of ferrous iron (Fe2+) and the expression of ferroptosis-associated molecules were detected. The binding between FTA and its target protein was confirmed by Co-immunoprecipitation (Co-IP), cellular thermal shift assay (CETSA), drug affinity responsive target stability (DARTS) and surface plasmon resonance (SPR). Our results demonstrated that FTA alleviated BDL-induced liver fibrosis in mice. FTA did not decrease the elevated amount of bile acids in BDL-treated mice, but reduced the bile acid-induced mitochondrial damage, oxidative stress and ferroptosis in hepatocytes, and also induced nuclear factor erythroid 2-related factor-2 (Nrf2) activation. In Nrf2 knock-out mice, the FTA-provided protection against BDL-induced liver fibrosis was disappeared, and FTA's inhibition on mitochondrial damage, oxidative stress and ferroptosis were lowered. Further results displayed that FTA could directly bind to Kelch-like ECH-associated protein-1 (Keap1), thereby activating Nrf2. Moreover, the BDL-induced liver fibrosis was markedly weakened in liver-specific Keap1 knockout mice. Hence, this study suggests that FTA alleviated the BDL-induced liver fibrosis through attenuating mitochondrial damage and ferroptosis in hepatocytes by activating Nrf2 via directly binding to Keap1.

Air-ventilated normothermic mechanical perfusion improves susceptibility to donation after circulatory death and cold preservation-induced cholestatic liver injury through PPAR-γ/UGT1A1 axis

End-ischemic normothermic mechanical perfusion (NMP) could provide a curative treatment to reduce cholestatic liver injury from donation after circulatory death (DCD) in donors. However, the underlying mechanism remains elusive. Our previous study demonstrated that air-ventilated NMP could improve functional recovery of DCD in a preclinical NMP rat model. Here, metabolomics analysis revealed that air-ventilated NMP alleviated DCD- and cold preservation-induced cholestatic liver injury, as shown by the elevated release of alanine aminotransferase (ALT), aspartate aminotransferase (AST), bilirubin, and γ-glutamyl transferase (GGT) in the perfusate (p < .05) and the reduction in the levels of bile acid metabolites, including ω-muricholic acid, glycohyodeoxycholic acid, glycocholic acid, and glycochenodeoxycholate (GCDC) in the perfused livers (p < .05). In addition, the expression of the key bile acid metabolism enzyme UDP-glucuronosyltransferase 1A1 (UGT1A1), which is predominantly expressed in hepatocytes, was substantially elevated in the DCD rat liver, followed by air-ventilated NMP (p < .05), and in vitro, this increase was induced by decreased GCDC and hypoxia-reoxygenation in the hepatic cells HepG2 and L02 (p < .05). Knockdown of UGT1A1 in hepatic cells by siRNA aggravated hepatic injury caused by GCDC and hypoxia-reoxygenation, as indicated by the ALT and AST levels in the supernatant. Mechanistically, UGT1A1 is transcriptionally regulated by peroxisome proliferator-activator receptor-γ (PPAR-γ) under hypoxia-physoxia. Taken together, our data revealed that air-ventilated NMP could alleviate DCD- and cold preservation-induced cholestatic liver injury through PPAR-γ/UGT1A1 axis. Based on the results from this study, air-ventilated NMP confers a promising approach for predicting and alleviating cholestatic liver injury through PPAR-γ/UGT1A1 axis.

Hepatic microcirculatory disturbance in liver diseases: intervention with traditional Chinese medicine

The liver, a complex parenchymal organ, possesses a distinctive microcirculatory system crucial for its physiological functions. An intricate interplay exists between hepatic microcirculatory disturbance and the manifestation of pathological features in diverse liver diseases. This review updates the main characteristics of hepatic microcirculatory disturbance, including hepatic sinusoidal capillarization, narrowing of sinusoidal space, portal hypertension, and pathological angiogenesis, as well as their formation mechanisms. It also summarized the detection methods for hepatic microcirculation. Simultaneously, we have also reviewed the characteristics of microcirculatory disturbance in diverse liver diseases such as acute liver failure, hepatic ischemia-reperfusion injury, viral hepatitis, non-alcoholic fatty liver disease, hepatic fibrosis, hepatic cirrhosis, and hepatocellular carcinoma. Finally, this review also summarizes the advancement in hepatic microcirculation attributed to traditional Chinese medicine (TCM) and its active metabolites, providing novel insights into the application of TCM in treating liver diseases.

Biomarkers of NRF2 signalling: Current status and future challenges

The cytoprotective transcription factor NRF2 regulates the expression of several hundred genes in mammalian cells and is a promising therapeutic target in a number of diseases associated with oxidative stress and inflammation. Hence, an ability to monitor basal and inducible NRF2 signalling is vital for mechanistic understanding in translational studies. Due to some caveats related to the direct measurement of NRF2 levels, the modulation of NRF2 activity is typically determined by measuring changes in the expression of one or more of its target genes and/or the associated protein products. However, there is a lack of consensus regarding the most relevant set of these genes/proteins that best represents NRF2 activity across cell types and species. We present the findings of a comprehensive literature search that according to stringent criteria identifies GCLC, GCLM, HMOX1, NQO1, SRXN1 and TXNRD1 as a robust panel of markers that are directly regulated by NRF2 in multiple cell and tissue types. We assess the relevance of these markers in clinically accessible biofluids and highlight future challenges in the development and use of NRF2 biomarkers in humans.

Structural identification and antioxidant activity of trans-9, trans-11, cis-15-conjugated linolenic acid converted by probiotics

The study aimed to determine the chemical structures of octadecatrienoic acid isomers produced by probiotics through the bioconversion of α-linolenic acid and to assess their antioxidant capacities. The chemical structures were identified using nuclear magnetic resonance spectroscopy (NMR) and mass spectrometry (MS), while the antioxidant capacities were evaluated in vitro and in cellular. The NMR signals obtained allowed for definitive characterization, with the main ion fragments detected being m/z 58.0062, 59.0140, 71.0141, 113.0616, 127.0777, and 181.5833. Compounds at concentrations below 40 μM maintained the antioxidant capacity of HepG2 cells by protecting endogenous antioxidative enzymes and mitochondrial membrane potential. However, doses higher than 40 μM increase oxidative damage and mitochondrial dysfunction. These results confirmed the structure of the probiotic-derived compound as trans9, trans11, cis15-conjugated linolenic acid. Additionally, appropriate doses of CLNA can alleviate oxidative stress induced by AAPH, while high doses aggravate cellular damage. These findings provide foundational information for the further exploration of probiotic-derived edible lipids.

Interaction of Garcinia cambogia (Gaertn.) Desr. and Drugs as a Possible Mechanism of Liver Injury: The Case of Montelukast

Overweight and obesity prevalence has increased worldwide. Apart from conventional approaches, people also resort to botanical supplements for reducing body weight, although several adverse events have been associated with these products. In this context, the present study aimed at evaluating the toxicity of Garcinia cambogia-based products and shedding light on the mechanisms involved. The suspected hepatotoxic reactions related to G. cambogia-containing products collected within the Italian Phytovigilance System (IPS) were examined. Then, an in vitro study was performed to evaluate the possible mechanisms responsible for the liver toxicity, focusing on the modulation of oxidative stress and Nrf2 expression. From March 2002 to March 2022, the IPS collected eight reports of hepatic adverse reactions related to G. cambogia, which exclusively involved women and were mostly severe. The causality assessment was probable in three cases, while it was possible in five. In the in vitro experiments, a low cytotoxicity of G. cambogia was observed. However, its combination with montelukast greatly reduced cell viability, increased the intracellular ROS levels, and affected the cytoplasmic Nrf2 expression, thus suggesting an impairment of the antioxidant and cytoprotective defenses. Overall, our results support the safety concerns about G. cambogia-containing supplements and shed light on the possible mechanisms underpinning its hepatotoxicity.