Targeting collagen homeostasis for the treatment of liver fibrosis: Opportunities and challenges

Collagen fibers quantification for liver fibrosis assessment using linear dichroism photoacoustic microscopy

Liver fibrosis represents a progressive pathological condition that can culminate in severe hepatic dysfunction, potentially advancing to cirrhosis and liver cancer. The extent of liver fibrosis is intrinsically associated with the quantity of collagen fibers. Although liver biopsy and ultrasound imaging are standard diagnostic tools, their application is constrained by risks of significant complications and variability in different investigators, respectively. In this study, we utilized linear dichroism photoacoustic microscopy (LDPAM) to visualize and quantify collagen fibers, which exhibit specific absorption of polarized light, subsequently calculating a collagen fibers degree of dichroism (CDOD) score. We obtained high-resolution images of liver structures, with an emphasis on collagen fibers within the hepatic tissue. Using the CDOD score, we categorized liver fibrosis into three distinct stages: normal, early, and advanced. For validation purposes, collagen fibers were visualized with Sirius-red staining and quantitatively assessed through the collagen proportional area (CPA) score. Our results demonstrated a significant correlation between the CDOD and CPA scores, with a Pearson coefficient of 0.95. This approach presents a promising and non-invasive method for assessing liver fibrosis by quantifying collagen fibers.

Skullcapflavone II induces G2/M phase arrest in hepatic stellate cells and suppresses hepatic fibrosis

RESEARCH PURPOSE

This investigation explored the therapeutic effects and mechanisms of Skullcapflavone II in hepatic fibrosis (HF).

MATERIALS AND METHODS

The optimal concentration of Skullcapflavone II for LX2 hepatic stellate cells was determined using the CCK8 assay. EdU staining and flow cytometry were utilised to assess cell proliferation and G2/M phase arrest. Mice with carbon tetrachloride-triggered HF were administered Skullcapflavone II at low (15 mg/day), medium (30 mg/day), and high (60 mg/day) doses. Subsequently, hepatic damage and fibrosis were assessed via body weight, liver index, biochemical markers, and histopathological staining. Immunohistochemistry for Collagen I and α-SMA were utilised to examine hepatic stellate cell (HSC) activation. RNA sequencing was utilised to ascertain differentially expressed genes. Molecular docking simulated interactions among Skullcapflavone II and target proteins as well as outcomes were validated by implementing western blotting, immunohistochemistry, and RT-qPCR.

RESULTS

Skullcapflavone II inhibited LX2 cell proliferation and triggered G2/M phase arrest. Its optimal intervention concentration was 160 μM. In vivo, it ameliorated hepatic function, diminished serum indicators of fibrosis, and suppressed HSC activation. Diminished collagen sediment was validated utilising histopathological examination, whereas immunohistochemistry indicated decreased expression of Collagen I and α-SMA. Additionally, molecular docking showed strong binding of Skullcapflavone II to DNA replication-related proteins. Western blotting and RT-qPCR implied that Skullcapflavone II disrupted DNA replication, which triggered G2/M arrest and hindered HSCs activation and proliferation.

CONCLUSION

The abovementioned mechanisms of action of Skullcapflavone II substantiate its prospective clinical application against HF.

Viscoelastic Mechanics: From Pathology and Cell Fate to Tissue Regeneration Biomaterial Development

Viscoelasticity is the mechanical feature of living tissues and the cellular extracellular matrix (ECM) and has been recognized as an essential biophysical cue in cell function and fate regulation, tissue development and homeostasis maintenance, and disease progression. These findings provide new insights for the development of biomaterials with comparable viscoelastic properties as native ECMs and the tissue matrix, displaying promising applications in regeneration medicine. In this review, the relationship between matrix viscoelasticity and tissue functions (e.g., development and regeneration) in physiological conditions and disease progression (e.g., aging, degenerative, fibrosis, and tumor) in pathological conditions will be especially highlighted to figure out the potential therapeutic target for disease treatment and inspiration for tissue regeneration related biomaterial development. Furthermore, findings and an understanding of the cell response to ECM viscoelasticity and the mechanism behind it are comprehensively summarized to provide a pathophysiological basis for viscoelastic biomaterials design. The advances of viscoelastic biomaterials on defect tissue repair are also reviewed, suggesting the significance of the native matrix matchable microenvironment on tissue regeneration. Although challenging, tunable viscoelastic biomaterials that match the mechanical properties of native tissues and ECMs show great promise. They could promote tissue regeneration, treat degenerative diseases, and support the development of organoids and artificial organs.

Advances in intrahepatic and extrahepatic vascular dysregulations in cirrhotic portal hypertension

Cirrhotic portal hypertension, the most prevalent and clinically significant complication of liver cirrhosis, manifests as elevated portal venous pressure and is associated with severe complications. Although much research on the mechanisms of portal hypertension has focused on liver fibrosis, less attention has been given to the role of intrahepatic and extrahepatic vascular dysfunction, particularly with respect to extrahepatic vasculature. While the role of hepatic fibrosis in cirrhotic portal hypertension is undeniable, the underlying mechanisms involving intrahepatic and extrahepatic vasculature are highly complex. Sinusoidal capillarization and endothelial dysfunction contribute to increased intrahepatic vascular resistance. Hemodynamic changes in the extrahepatic circulation, including splanchnic vasodilation and hyperdynamic circulation, play a significant role in the development of portal hypertension. Additionally, therapeutic strategies targeting these vascular mechanisms are diverse, including improvement of sinusoidal microcirculation, therapies targeting hepatic stellate cells activation, and pharmacological modulation of systemic vascular tone. Therefore, in this review, we will discuss the vascular-related mechanisms and treatment progress of portal hypertension in cirrhosis to provide a new theoretical basis and practical guidance for clinical treatment.

Hepatic stellate cell-targeted chemo-gene therapy for liver fibrosis using fluorinated peptide-lipid hybrid nanoparticles

Exploring precise and effective treatments for liver fibrosis is urgent. The effective therapy for liver fibrosis depends on the specific delivery of antifibrotic drugs to activated hepatic stellate cells (aHSCs). However, this is a challenging task due to pathological barriers, primarily caused by collagen deposition. This study developed vitamin A-functionalized fluorinated peptide/lipid hybrid nanoparticles to co-deliver sorafenib and siRNA against HSP47 (SF-siHSP47@VFPL NPs). This nanoparticle formulation offers significant advantages due to its fluorine‑fluorine and electrostatic interactions, allowing for high SF and siHSP47 loading efficiency and sustained drug release. Importantly, in vitro cell uptake and in vivo biodistribution revealed that VA functionalization significantly improved aHSC-targeted delivery efficiency by engaging retinol-binding protein receptors on HSCs. Furthermore, it dramatically reduced extracellular matrix deposition, as evidenced by diminished levels of liver fibrosis-associated genes (HSP47, TIMP-1, and collagen I), promoting collagen breakdown and preventing collagen production, thus overcoming drug delivery barriers. Thus, SF-siHSP47@VFPL NPs demonstrated optimal antifibrotic effects by triggering apoptosis and ferroptosis in aHSCs. In liver fibrosis mouse models, SF-siHSP47@VFPL NPs remodeled the pathological environment and restored liver functionality through a marked reduction in serum liver transferases, hydroxyproline content, collagen deposition, and α-SMA and CD31 expression in liver tissue, resulting in alleviated liver fibrosis. Consequently, SF-siHSP47@VFPL NPs showed significant potential for HSC-targeted, chemo-gene therapy in the treatment of liver fibrosis.

Interference with mitochondrial function as part of the antifibrogenic effect of Rilpivirine: A step towards novel targets in hepatic stellate cell activation

Activated hepatic stellate cells (aHSCs), the main perpetrators of liver fibrosis, are a promising therapeutic target in the treatment of chronic liver disease. During liver injury, HSCs transcend from a quiescent to a fibrotic phenotype, a process which involves major metabolic reprogramming with altered mitochondrial function. The antiretroviral drug Rilpivirine (RPV) has demonstrated a hepatoprotective and specifically antifibrotic effect in several animal models of chronic liver injury, as well as in vitro. Herein, we use HSCs activated with the profibrogenic cytokine TGF-β to explore whether mitochondrial function is implicated in this effect. The mitochondrial bioenergetic profile, morphology and dynamics of TGF-β-treated cells (48 h) were altered and these effects were prevented by co-treatment with clinically relevant concentrations of RPV. A MitoStress Test (Seahorse Analyzer) revealed that TGF-β increased both oxygen consumption rate (basal respiration, maximal respiration and spare respiratory capacity) and extracellular acidification rate (indicative of increased glycolysis). Cells exposed to TGF-β also displayed diminished mitochondrial membrane potential and enhanced mitochondrial fission. All of these effects were rescued with RPV. RNA sequencing analysis of cells exposed to TGF-β revealed the presence of 338 differentially expressed genes that encode mitochondrial proteins (mito-DEGs), of which 139 and 199 were significantly up- and down-regulated (adjusted p<0.05). This alteration in 15 (10.79 %) and 31 (22.03 %) of the up-regulated and 16 (8.04 %) and 49 (24.62 %) of the down-regulated mitoDEGs was prevented with co-exposure to RPV 4μM or 8μM, respectively. In conclusion, alterations in mitochondrial function are implicated in the antifibrogenic action of RPV, pointing to potential novel antifibrotic targets.

Inhibition of intrahepatic monocyte recruitment by Cenicriviroc and extracellular matrix degradation by MMP1 synergistically attenuate liver inflammation and fibrogenesis in vivo

The chemokine (CCL)-chemokine receptor (CCR2) interaction, importantly CCL2-CCR2, involved in the intrahepatic recruitment of monocytes upon liver injury promotes liver fibrosis. CCL2-CCR2 antagonism using Cenicriviroc (CVC) showed promising results in several preclinical studies. Unfortunately, CVC failed in phase III clinical trials due to lack of efficacy to treat liver fibrosis. Lack of efficacy could be attributed to the fact that macrophages are also involved in disease resolution by secreting matrix metalloproteinases (MMPs) to degrade extracellular matrix (ECM), thereby inhibiting hepatic stellate cells (HSCs) activation. HSCs are the key pathogenic cell types in liver fibrosis that secrete excessive amounts of ECM causing liver stiffening and liver dysfunction. Knowing the detrimental role of intrahepatic monocyte recruitment, ECM, and HSCs activation during liver injury, we hypothesize that combining CVC and MMP (MMP1) could reverse liver fibrosis. We evaluated the effects of CVC, MMP1 and CVC + MMP1 in vitro and in vivo in CCl4-induced liver injury mouse model. We observed that CVC + MMP1 inhibited macrophage migration, and TGF-β induced collagen-I expression in fibroblasts in vitro. In vivo, MMP1 + CVC significantly inhibited normalized liver weights, and improved liver function without any adverse effects. Moreover, MMP1 + CVC inhibited monocyte infiltration and liver inflammation as confirmed by F4/80 and CD11b staining, and TNFα gene expression. MMP1 + CVC also ameliorated liver fibrogenesis via inhibiting HSCs activation as assessed by collagen-I staining and collagen-I and α-SMA mRNA expression. In conclusion, we demonstrated that a combination therapeutic approach by combining CVC and MMP1 to inhibit intrahepatic monocyte recruitment and increasing collagen degradation respectively ameliorate liver inflammation and fibrosis.

Investigating the Antifibrotic Effects of β-Citronellol on a TGF-β1-Stimulated LX-2 Hepatic Stellate Cell Model

Liver fibrosis, a consequence of chronic liver damage or inflammation, is characterized by the excessive buildup of extracellular matrix components. This progressive condition significantly raises the risk of severe liver diseases like cirrhosis and hepatocellular carcinoma. The lack of approved therapeutics underscores the urgent need for novel anti-fibrotic drugs. Hepatic stellate cells (HSCs), key players in fibrogenesis, are promising targets for drug discovery. This study investigated the anti-fibrotic potential of Citrus hystrix DC. (KL) and its bioactive compound, β-citronellol (β-CIT), in a human HSC cell line (LX-2). Cells exposed to TGF-β1 to induce fibrogenesis were co-treated with crude KL extract and β-CIT. Gene expression was analyzed by real-time qRT-PCR to assess fibrosis-associated genes (ACTA2, COL1A1, TIMP1, SMAD2). The release of matrix metalloproteinase 9 (MMP-9) was measured by ELISA. Proteomic analysis and molecular docking identified potential signaling proteins and modeled protein-ligand interactions. The results showed that both crude KL extract and β-CIT suppressed HSC activation genes and MMP-9 levels. The MAPK signaling pathway emerged as a potential target of β-CIT. This study demonstrates the ability of KL extract and β-CIT to inhibit HSC activation during TGF-β1-induced fibrogenesis, suggesting a promising role of β-CIT in anti-hepatic fibrosis therapies.

Inhibition of the rapamycin-insensitive mTORC1 /4E-BP1 axis attenuates TGF-β1-induced fibrotic response in human Tenon's fibroblasts

Subconjunctival fibrosis is the major cause of failure in both conventional and modern minimally invasive glaucoma surgeries (MIGSs) with subconjunctival filtration. The search for safe and effective anti-fibrotic agents is critical for improving long-term surgical outcomes. In this study, we investigated the effect of inhibiting the rapamycin-insensitive mTORC1/4E-BP1 axis on the transforming growth factor-beta 1(TGF-β1)-induced fibrotic responses in human Tenon's fibroblasts (HTFs), as well as in a rat model of glaucoma filtration surgery (GFS). Primary cultured HTFs were treated with 3 ng/mL TGF-β1 for 24 h, followed by treatment with 10 μM CZ415 for additional 24 h. Rapamycin (10 μM) was utilized as a control for mTORC1/4E-BP1 signaling insensitivity. The expression levels of fibrosis-associated molecules were measured using quantitative real-time PCR, Western blotting, and immunofluorescence analysis. Cell migration was assessed through the scratch wound assay. Additionally, a rat model of GFS was employed to evaluate the anti-fibrotic effect of CZ415 in vivo. Our findings indicated that both rapamycin and CZ415 treatment significantly reduced the TGF-β1-induced cell proliferation, migration, and the expression of pro-fibrotic factors in HTFs. CZ415 also more effectively inhibited TGF-β1-mediated collagen synthesis in HTFs compared to rapamycin. Activation of mTORC1/4E-BP signaling following TGF-β1 exposure was highly suppressed by CZ415 but was only modestly inhibited by rapamycin. Furthermore, CZ415 was found to decrease subconjunctival collagen deposition in rats post GFS. Our results suggest that rapamycin-insensitive mTORC1/4E-BP1 signaling plays a critical role in TGF-β1-driven collagen synthesis in HTFs. This study demonstrated that inhibition of the mTORC1/4E-BP1 axis offers superior anti-fibrotic efficacy compared to rapamycin and represents a promising target for improving the success rate of both traditional and modern GFSs.

SIRT3: A potential therapeutic target for liver fibrosis

Sirtuin3 (SIRT3) is a nicotinamide adenine dinucleotide (NAD+)-dependent protein deacetylase located in the mitochondria, which mainly regulates the acetylation of mitochondrial proteins. In addition, SIRT3 is involved in critical biological processes, including oxidative stress, inflammation, DNA damage, and apoptosis, all of which are closely related to the progression of liver disease. Liver fibrosis characterized by the deposition of extracellular matrix is a result of long termed or repeated liver damage, frequently accompanied by damaged hepatocytes, the recruitment of inflammatory cells, and the activation of hepatic stellate cells. Based on the functions and pharmacology of SIRT3, we will review its roles in liver fibrosis from three aspects: First, the main functions and pharmacological effects of SIRT3 were investigated based on its structure. Second, the roles of SIRT3 in major cells in the liver were summarized to reveal its mechanism in developing liver fibrosis. Last, drugs that regulate SIRT3 to prevent and treat liver fibrosis were discussed. In conclusion, exploring the pharmacological effects of SIRT3, especially in the liver, may be a potential strategy for treating liver fibrosis.

Understanding the matrix: collagen modifications in tumors and their implications for immunotherapy

Tumors are highly complex and heterogenous ecosystems where malignant cells interact with healthy cells and the surrounding extracellular matrix (ECM). Solid tumors contain large ECM deposits that can constitute up to 60% of the tumor mass. This supports the survival and growth of cancerous cells and plays a critical role in the response to immune therapy. There is untapped potential in targeting the ECM and cell-ECM interactions to improve existing immune therapy and explore novel therapeutic strategies. The most abundant proteins in the ECM are the collagen family. There are 28 different collagen subtypes that can undergo several post-translational modifications (PTMs), which alter both their structure and functionality. Here, we review current knowledge on tumor collagen composition and the consequences of collagen PTMs affecting receptor binding, cell migration and tumor stiffness. Furthermore, we discuss how these alterations impact tumor immune responses and how collagen could be targeted to treat cancer.

Isolation and purification of polysaccharides from Bupleurum marginatum Wall.ex DC and their anti-liver fibrosis activities

Bupleurum marginatum Wall.ex DC [Apiaceae] (BM)is widely grown in southwestern China, and the whole plant is used as Traditional Chinese Medicine (TCM). Polysaccharides are main natural products in lots of TCM and have been studied for their effects of reducing oxidative stress, anti-inflammation and immune regulation. Herein, we investigated the extraction techniques of Bupleurum marginatum Wall.ex DC polysaccharides (BMP), the identification of their key components, and their ability to inhibit liver fibrosis in both cellular and animal models. Component identification indicated that monosaccharides in BMP mainly consisted of glucose, galactose, mannose, rhamnose, arabinose, and xylose. In vivo analysis revealed that BMP provided significant protective effects on N-Nitroso dimethylamine (NDMA)-induced liver fibrosis rats through reducing hepatomegaly, reducing tissue inflammation, and reducing collagen deposition. BMP also improved the hepatobiliary system and liver metabolism in accord to reduce the serum levels of ALT, AST, ALP, r-GT, and TBIL. In addition, BMP could reduce the level of inflammation and fibrosis through inhibition of IL-1β and TGF-β1. Cellular studies showed that the BMP could provide therapeutic effects on lipopolysaccharide (LPS)-induced cellular fibrosis model, and could reduce the level of inflammation and fibrosis by decreasing the level of TGF-β1, IL-1β, and TNF-α. Our study demonstrated that BMP may provide a new therapy strategy of liver injury and liver fibrosis.

C-X-C motif chemokine receptor 4 inhibition promotes the effect of plantamajoside in hepatocellular carcinoma

BACKGROUND AND STUDY AIM

Hepatocellular carcinoma (HCC) is the fifth leading cause of cancer-related mortality worldwide, and, more than half of these cases are diagnosed in China. However, effective treatment for HCC is still limited.

MATERIAL AND METHODS

C-X-C motif chemokine receptor 4 (CXCR4) was first activated and inhibited in HepG2 cells using a pharmacological method. HepG2 cell proliferation was detected using the CCK-8 method. Metastasis and apoptosis of HepG2 cells were detected using wound healing and flow cytometry. The expression of each target molecule related to metastasis and invasion, such as MMPs, E-cadherin and the PI3K/AKT/Mcl-1/PARP signaling pathway was detected by western blotting. The secretion of molecular metastases was detected using competitive ELISA.

RESULTS

This study constructed a CXCR4 activation and inhibition model in HepG2 cells. CXCR4 inhibition promoted the inhibitory effect of plantamajoside on the proliferation and metastasis of cells, which led to apoptosis. Furthermore, we found that the expression of apoptosis-related proteins was increased after treatment with plantamajoside combined with CXCR4 inhibition. In addition, the expression and secretion of pro-metastatic proteins, including MMPs and E-cadherin were decreased. We also noticed that this effect might be mediated by the PI3K/AKT/Mcl-1/PARP signaling pathway.

CONCLUSION

CXCR4 inhibition may contribute to the treatment of HCC. Inhibition of CXCR4 expression contributes to the therapeutic effect of plantamajoside; the effect of plantamajoside might be mediated by the PI3K/AKT/Mcl-1/PARP signaling pathway; and CXCR4 might be a therapeutic target of HCC.