Inhibition of apoptosis of activated hepatic stellate cells by tissue inhibitor of metalloproteinase-1 is mediated via effects on matrix metalloproteinase inhibition: implications for reversibility of liver fibrosis

TIMP-1 Promotes Expression of MCP-1 and Macrophage Migration by Inducing Fli-1 in Experimental Liver Fibrosis

Background and Aims

Tissue inhibitor of metalloproteinase-1 (TIMP-1) plays a role in the excessive generation of extracellular matrix in liver fibrosis. This study aimed to explore the pathways through which TIMP-1 controls monocyte chemoattractant protein-1 (MCP-1) expression and promotes hepatic macrophage recruitment.

Methods

Liver fibrosis was triggered through carbon tetrachloride, and an adeno-associated virus containing small interfering RNA targeting TIMP-1 (siRNA-TIMP-1) was administered to both rats and mice. We assessed the extent of fibrosis and macrophage recruitment. The molecular mechanisms regulating macrophage recruitment by TIMP-1 were investigated through transwell migration assays, luciferase reporter assays, the use of pharmacological modulators, and an analysis of extracellular vesicles (EVs).

Results

siRNA-TIMP-1 alleviated carbon tetrachloride-induced liver fibrosis, reducing macrophage migration and MCP-1 expression. Co-culturing macrophages with hepatic stellate cells (HSCs) post-TIMP-1 downregulation inhibited macrophage migration. In siRNA-TIMP-1-treated HSCs, microRNA-145 (miRNA-145) expression increased, while the expression of Friend leukemia virus integration-1 (Fli-1) and MCP-1 was inhibited. Downregulation of Fli-1 led to decreased MCP-1 expression, whereas Fli-1 overexpression increased MCP-1 expression within HSCs. Transfection with miRNA-145 mimics reduced the expression of both Fli-1 and MCP-1, while miRNA-145 inhibitors elevated the expression of both Fli-1 and MCP-1 in HSCs. miRNA-145 bound directly to the 3'-UTR of Fli-1, and miRNA-145-enriched EVs secreted by HSCs after TIMP-1 downregulation influenced macrophage recruitment.

Conclusions

TIMP-1 induces Fli-1 expression through miRNA-145, subsequently increasing MCP-1 expression and macrophage recruitment. MiRNA-145-enriched EVs from HSCs can transmit biological information and magnify the function of TIMP-1.

Plasticity, heterogeneity, and multifunctionality of hepatic stellate cells in liver pathophysiology

HSCs, the resident pericytes of the liver, have consistently been at the forefront of liver research due to their crucial roles in various hepatic pathological processes. Prior literature often depicted HSCs in a binary framework, categorizing them as either quiescent or activated. However, recent advances in HSC research, particularly the advent of single-cell RNA-sequencing, have revolutionized our understanding of these cells. This sophisticated technique offers an unparalleled, high-resolution insight into HSC populations, uncovering a spectrum of diversity and functional heterogeneity across various physiological states of the liver, ranging from liver development to the liver aging process. The single-cell RNA-sequencing revelations have also highlighted the intrinsic plasticity of HSCs and underscored their complex roles in a myriad of pathophysiological processes, including liver injury, repair, and carcinogenesis. This review aims to integrate and clarify these recent discoveries, focusing on how the inherent plasticity of HSCs is central to their dynamic roles both in maintaining liver homeostasis and orchestrating responses to liver injury. Future research will clarify whether findings from rodent models can be translated to human livers and guide how these insights are harnessed to develop targeted therapeutic interventions.

The TIMP protein family: diverse roles in pathophysiology

The tissue inhibitors of matrix metalloproteinases (TIMPs) are a family of four matrisome proteins classically defined by their roles as the primary endogenous inhibitors of metalloproteinases (MPs). Their functions however are not limited to MP inhibition, with each family member harboring numerous MP-independent biological functions that play key roles in processes such as inflammation and apoptosis. Because of these multifaceted functions, TIMPs have been cited in diverse pathophysiological contexts. Herein, we provide a comprehensive overview of the MP-dependent and -independent roles of TIMPs across a range of pathological conditions. The potential therapeutic and biomarker applications of TIMPs in these disease contexts are also considered, highlighting the biomedical promise of this complex and often misunderstood protein family.

The role of sinusoidal endothelial cells and TIMP1 in the regulation of fibrosis in a novel human liver 3D NASH model

BACKGROUND

The prevalence of NAFLD is rapidly increasing. NAFLD can progress to NASH, fibrosis, cirrhosis, and HCC, which will soon become the main causes of liver transplantation. To date, no effective drug for NASH has been approved by the Food and Drug Administration. This is partly due to the lack of reliable human in vitro models. Here, we present a novel human liver spheroid model that can be used to study the mechanisms underlying liver fibrosis formation and degradation.

METHODS AND RESULTS

Such spheroids, which contain hepatocytes, stellate cells, KC, and LSECs, spontaneously develop fibrosis that is exacerbated by treatment with free fatty acids. Conditioned medium from activated LSECs caused similar activation of fibrosis in spheroids containing primary human hepatocyte and NPCs, indicating the action of soluble mediators from the LSECs. Spheroids containing LSECs treated with free fatty acids produced tissue inhibitor of metalloproteinases inhibitor 1, a matrix metalloproteinases inhibitor important for fibrosis progression. Tissue inhibitor of metalloproteinases inhibitor 1 knockdown using siRNA led to a reduction in collagen and procollagen accumulation, which could be partially rescued using a potent matrix metalloproteinases inhibitor. Interestingly, tissue inhibitor of metalloproteinases inhibitor 1 was found to be expressed at higher levels, specifically in a subtype of endothelial cells in the pericentral region of human fibrotic livers, than in control livers.

CONCLUSION

Potential anti-NASH drugs and compounds were evaluated for their efficacy in reducing collagen accumulation, and we found differences in specificity between spheroids with and without LSECs. This new human NASH model may reveal novel mechanisms for the regulation of liver fibrosis and provide a more appropriate model for screening drugs against NASH.

Antifibrogenic and apoptotic effects of Ocoxin in cultured rat hepatic stellate cells

Ocoxin is a nutritional supplement that has been shown to exert antioxidant and immunomodulatory responses in patients with chronic hepatitis C. The present work aimed to determine the effects of Ocoxin on activated hepatic stellate cells (HSC), the cell type mainly responsible for collagen deposition in the fibrotic liver. Ocoxin was found to reduce the survival of a cell line of immortalized non-tumoral rat HSC in a dose-response fashion and to diminish collagen type I levels. This latter effect was observed even at doses not affecting cell survival, pointing to an antifibrogenic action for the supplement. The decrease in viability exerted by Ocoxin on HSC correlated with an increase in histone-associated fragments in the cytoplasm and with increased activity of caspase-3, indicating the induction of apoptosis. To determine the molecular mechanisms mediating Ocoxin-induced apoptosis, the activation of members of the MAPK family was analyzed. Incubation of HSC with Ocoxin caused a transient and dramatic enhancement on ERK, JNK, and p38 MAPK phosphorylation levels. Using specific inhibitors for these enzymes, p38 MAPK was identified as a key mediator of the apoptotic effect of Ocoxin on HSC.

Found in translation-Fibrosis in metabolic dysfunction-associated steatohepatitis (MASH)

Metabolic dysfunction-associated steatohepatitis (MASH) is a severe form of liver disease that poses a global health threat because of its potential to progress to advanced fibrosis, leading to cirrhosis and liver cancer. Recent advances in single-cell methodologies, refined disease models, and genetic and epigenetic insights have provided a nuanced understanding of MASH fibrogenesis, with substantial cellular heterogeneity in MASH livers providing potentially targetable cell-cell interactions and behavior. Unlike fibrogenesis, mechanisms underlying fibrosis regression in MASH are still inadequately understood, although antifibrotic targets have been recently identified. A refined antifibrotic treatment framework could lead to noninvasive assessment and targeted therapies that preserve hepatocellular function and restore the liver's architectural integrity.

Correlation between SDF-1α, CD34 positive hematopoietic stem cells and CXCR4 expression with liver fibrosis in CCl4 rat model

BACKGROUND

One of the most frequent disorders is liver fibrosis. An improved understanding of the different events during the process of liver fibrosis & its reversibility could be helpful in its staging and in finding potential therapeutic agents.

AIM

The goal of this research was to evaluate the relationship among CD34 + HPSCs, SDF-1α, and CXCR4 receptor expression with the percentage of the area of hepatic fibrosis.

MATERIALS AND METHODS

Thirty-six male Sprague-Dawley rats were separated into the control group, liver injury group & spontaneous reversion group. The liver injury was induced by using 2 ml/kg CCl4 twice a week. Flow cytometric examination of CD34 + cells in the blood & liver was performed. Bone marrow & liver samples were taken for evaluation of the SDF-1α mRNA by PCR. Liver specimens were stained for histopathological and CXCR4 immuno-expression evaluation.

RESULTS

In the liver injury group, the hepatic enzymes, fibrosis area percentage, CXCR4 receptor expression in the liver, CD34 + cells in the blood and bone marrow & the level SDF-1α in the liver and its concentration gradient were statistically significantly elevated with the progression of the liver fibrosis. On the contrary, SDF-1α in the bone marrow was statistically significantly reduced with the development of liver fibrosis. During the spontaneous reversion group, all the studied parameters apart from SDF-1α in the bone marrow were statistically substantially decreased compared with the liver injury group. We found a statistically substantial positive correlation between fibrosis area and all of the following: liver enzymes, CXCR4 receptor expression in the liver, CD34 + cells in the blood and liver, and SDF- 1α in the liver and its concentration gradient. In conclusion, in CCl4 rat model, the fibrosis area is significantly correlated with many parameters in the blood, bone marrow, and liver, which can be used during the process of follow-up during the therapeutic interventions.

Role of Ferroptosis in Fibrosis Diseases

Ferroptosis is a pervasive non-apoptotic mode of cell death that is different from autophagy or necrosis. It is mainly caused by an imbalance between the production and degradation of lipid reactive oxygen species in cells. Several metabolic pathways and biochemical processes, such as amino acid and lipid metabolism, iron handling, and mitochondrial respiration, affect and regulate cell sensitivity to peroxidation and ferroptosis. Organ fibrosis, a pathological manifestation of several etiological conditions, leads to chronic tissue injury and is characterized by excessive deposition of extracellular matrix components. Excessive tissue fibrosis can have diverse pathophysiological effects on several organ systems, eventually causing organ dysfunction and failure. The current manuscript provides a review that illustrates the link between ferroptosis and organ fibrosis and to better understand the underlying mechanisms. It provides novel potential therapeutic approaches and targets for fibrosis diseases.

p53 and Myofibroblast Apoptosis in Organ Fibrosis

Organ fibrosis represents a dysregulated, maladaptive wound repair response that results in progressive disruption of normal tissue architecture leading to detrimental deterioration in physiological function, and significant morbidity/mortality. Fibrosis is thought to contribute to nearly 50% of all deaths in the Western world with current treatment modalities effective in slowing disease progression but not effective in restoring organ function or reversing fibrotic changes. When physiological wound repair is complete, myofibroblasts are programmed to undergo cell death and self-clearance, however, in fibrosis there is a characteristic absence of myofibroblast apoptosis. It has been shown that in fibrosis, myofibroblasts adopt an apoptotic-resistant, highly proliferative phenotype leading to persistent myofibroblast activation and perpetuation of the fibrotic disease process. Recently, this pathological adaptation has been linked to dysregulated expression of tumour suppressor gene p53. In this review, we discuss p53 dysregulation and apoptotic failure in myofibroblasts and demonstrate its consistent link to fibrotic disease development in all types of organ fibrosis. An enhanced understanding of the role of p53 dysregulation and myofibroblast apoptosis may aid in future novel therapeutic and/or diagnostic strategies in organ fibrosis.

literammp-9 mRNA Expression and Bridging Fibrosis Progression in Toxic Liver Injury

Developing liver disease treatments, in which fibrosis is a key pathogenetic link, still remains an urgent problem in hepatology. In the present study, the level of mmp-9 mRNA expression and the number of FAP+, α-SMA+, CD45+ cells were analyzed at nine time points of fibrosis and cirrhosis. It was found that in the case of liver fibrosis, the choice of the optimal reference gene depended on the stage of fibrogenesis. When studying the specific stages rather than the entire process in a long-term experiment, it was shown that choosing an optimal reference gene has to be done additionally. In this case, the mmp-9 mRNA expression level should be considered as a marker of liver fibrosis initiation and development but not as that of cirrhosis progression. In the liver, two morphologically heterogeneous populations of myofibroblasts were simultaneously identified as able to synthesize various types of immunohistochemical markers. It was found that the FAP+ cells were the main contributor to the development of portal fibrosis and the initial stages of bridging fibrosis. In the selected experimental model, fibrosis initiation and the development stages preceding parenchyma restructuring were accompanied by a low level of inflammation.

A standardized pomegranate fruit extract ameliorates thioacetamide-induced liver fibrosis in rats via AGE-RAGE-ROS signaling

This work aimed to investigate a possible mechanism that may mediate the hepatoprotective effects of pomegranate fruit extract (PFE) against thioacetamide (THIO)-induced liver fibrosis in rats. Male Sprague Dawley rats were randomly allocated into four groups (n = 8 each): control; PFE (150 mg/kg/day, orally); THIO (200 mg/kg, i.p, 3 times a week); and THIO and PFE-treated groups. Oral PFE treatment decreased liver/body weight ratio by 12.4%, diminished serum function levels of ALT, AST, ALP, LDH, and total bilirubin, increased serum albumin, boosted hepatic GSH (by 35.6%) and SOD (by 17.5%), and significantly reduced hepatic levels of ROS, MDA, 4-HNE, AGEs, and RAGE in THIO-fibrotic rats relative to untreated THIO group. Moreover, PFE administration downregulated the hepatic levels of profibrotic TGF-β1 (by 23.0%, P < 0.001) and TIMP-1 (by 41.5%, P < 0.001), attenuated α-SMA protein expression, decreased serum HA levels (by 41.3%), and reduced the hepatic levels of the fibrosis markers hydroxyproline (by 26.0%, P < 0.001), collagen type IV (by 44.3%, P < 0.001) and laminin (by 43.4%, P < 0.001) compared to the untreated THIO group. The histopathological examination has corroborated these findings, where PFE decreased hepatic nodule incidence, attenuated portal necroinflammation and reduced extent of fibrosis. These findings may suggest that oral PFE administration could slow the progression of hepatic fibrogenesis via reducing hepatic levels of AGEs, RAGE, ROS, TGF-β1, and TIMP-1.

Miglustat, a glucosylceramide synthase inhibitor, mitigates liver fibrosis through TGF-β/Smad pathway suppression in hepatic stellate cells

Transforming growth factor (TGF)-β/Smad pathway is implicated in the pathogenesis of liver fibrosis, a condition characterized by excessive deposition of extracellular matrix (ECM) proteins such as collagen in response to chronic inflammation. It has been reported that ceramide regulates collagen production through TGF-β/Smad pathway activation. In this study, we examined whether miglustat, an inhibitor of glucosylceramide synthase, can suppress liver fibrosis by reducing TGF-β/Smad pathway activity. Human hepatic stellate cells (HHSteCs) were cultured with TGF-β and multiple miglustat concentrations to examine dose-dependent effects on the expression levels of ECM-related genes and Smad proteins. To evaluate the efficacy of miglustat for fibrosis mitigation, C57BL/6 mice were treated with carbon tetrachloride (CCl₄) for 4 weeks to induce liver fibrosis, followed by combined CCl₄ plus miglustat for a further 2 weeks. To examine if miglustat can also prevent fibrosis, mice were treated with CCl₄ for 2 weeks, followed by CCl₄ plus miglustat for 2 weeks. Miglustat dose-dependently downregulated expression of α-smooth muscle actin and ECM components in TGF-β-treated HHSteCs. Both phosphorylation and nuclear translocation of Smad2 and Smad3 were also suppressed by miglustat treatment. Sirius-Red staining and hydroxyproline assays of model mouse liver samples revealed that miglustat reduced fibrosis, an effect accompanied by decreased expression of ECM. Our findings suggest that miglustat can both prevent and reverse liver fibrosis by inhibiting TGF-β/Smad pathway.

IL-10 is not anti-fibrotic but pro-fibrotic in endometriosis: IL-10 treatment of endometriotic stromal cells in vitro promotes myofibroblast proliferation and collagen type I protein expression

STUDY QUESTION

Is interleukin-10 (IL-10) anti-fibrotic in endometriosis?

SUMMARY ANSWER

IL-10 is not anti-fibrotic but pro-fibrotic in endometriosis, because IL-10 treatment of endometriotic stromal cells in vitro promotes myofibroblast proliferation and collagen type I protein expression.

WHAT IS KNOWN ALREADY

We previously showed that persistent activation of signal transducer and activator of transcription 3 (STAT3) via IL-6 trans-signaling promotes fibrosis of endometriosis. Studies showed marked anti-fibrotic effects of IL-10 via the STAT3 signaling pathway, which is generally considered to be anti-inflammatory, in various organs.

STUDY DESIGN, SIZE, DURATION

Endometrial and/or endometriotic samples of 54 patients who had histological evidence of deep endometriosis, and endometrial samples from 30 healthy fertile women were analyzed.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The effects of IL-10/STAT3 signaling as well as inhibition of STAT3 activation by knockdown of STAT3 gene on the pro-fibrotic phenotype in endometrial and endometriotic stromal cells in vitro were investigated. Then, the effects of various time points of IL-10 treatment in combination with transforming growth factor (TGF)-β1 and/or IL-6/soluble IL-6 receptor (sIL-6R) on the profibrotic phenotype of endometrial and endometriotic stromal cells were investigated.

MAIN RESULTS AND THE ROLE OF CHANCE

IL-10 induced pro-fibrotic phenotype (cell proliferation, collagen type I synthesis, α-smooth muscle actin positive stress fibers and collagen gel contraction) of endometriotic stromal cells. Knockdown of STAT3 gene decreased the IL-10 induced pro-fibrotic phenotype of endometriotic stromal cells. In contrast, IL-10 had no significant effects on pro-fibrotic phenotype of endometrial stromal cells of healthy women. Sequential IL-10 treatment with or without TGF-β1 and/or IL-6/sIL-6R induced persistent activation of STAT3 and significantly increased proliferation of myofibroblasts (cells with α-smooth muscle actin positive stress fibers) and protein expression of collagen type I in endometriotic stromal cells. TGF-β1 and/or IL-6/sIL6RIL-6/sIL6R treatment significantly increased tissue inhibitor of metalloproteinase 1 (TIMP1) protein expression, whereas IL-10 had no significant effects. Knockdown of STAT3 gene significantly decreased the TGF-β1 and/or IL-6/sIL6R induced TIMP1 protein expression. In contrast, pre-treatment with IL-10 before TGF-β1 and/or IL-6/sIL-6R treatment and sequential IL-10 treatment with or without TGF-β1 and/or IL-6/sIL-6R significantly decreased proliferation of fibroblasts (cells without α-smooth muscle actin positive stress fibers) and collagen type I protein expression in endometrial stromal cells of healthy women.

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

Given the large number of complex interactions and signaling pathways of pro- and anti-inflammatory mediators that are involved in the pathophysiology of endometriosis, the present study investigated only a very small portion of the whole. Further in vivo studies are required to validate the present findings.

WIDER IMPLICATIONS OF THE FINDINGS

Inflammatory mediators in the pathophysiology of endometriosis have been extensively investigated as potential therapeutic targets. However, the present study showed that anti-inflammatory signals of IL-10 and IL-6 through persistent STAT3 activation may promote endometriosis fibrosis. Therapeutic strategies, such as suppression of 'inflammation', might dysregulate the cross-regulation of 'pro- and anti-inflammatory mediators', leading to detrimental effects in patients with endometriosis, such as fibrosis. To develop new, but not deleterious, therapeutic strategies, studies are required to investigate whether, how and what 'anti-inflammatory mediators' along with pro-inflammatory mediators are involved in individual patients with endometriosis.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported in part by KARL STORZ SE & Co. KG (Tuttlingen, Germany). The authors have no conflict of interest to disclose.

Molecular Advances in MAFLD—A Link between Sphingolipids and Extracellular Matrix in Development and Progression to Fibrosis

Metabolic-Associated Fatty Liver Disease (MAFLD) is a major cause of liver diseases globally and its prevalence is expected to grow in the coming decades. The main cause of MAFLD development is changed in the composition of the extracellular matrix (ECM). Increased production of matrix molecules and inflammatory processes lead to progressive fibrosis, cirrhosis, and ultimately liver failure. In addition, increased accumulation of sphingolipids accompanied by increased expression of pro-inflammatory cytokines in the ECM is closely related to lipogenesis, MAFLD development, and its progression to fibrosis. In our work, we will summarize all information regarding the role of sphingolipids e.g., ceramide and S1P in MAFLD development. These sphingolipids seem to have the most significant effect on macrophages and, consequently, HSCs which trigger the entire cascade of overproduction matrix molecules, especially type I and III collagen, proteoglycans, elastin, and also tissue inhibitors of metalloproteinases, which as a result cause the development of liver fibrosis.

Matrix Metalloproteinases: From Molecular Mechanisms to Physiology, Pathophysiology, and Pharmacology

The first matrix metalloproteinase (MMP) was discovered in 1962 from the tail of a tadpole by its ability to degrade collagen. As their name suggests, matrix metalloproteinases are proteases capable of remodeling the extracellular matrix. More recently, MMPs have been demonstrated to play numerous additional biologic roles in cell signaling, immune regulation, and transcriptional control, all of which are unrelated to the degradation of the extracellular matrix. In this review, we will present milestones and major discoveries of MMP research, including various clinical trials for the use of MMP inhibitors. We will discuss the reasons behind the failures of most MMP inhibitors for the treatment of cancer and inflammatory diseases. There are still misconceptions about the pathophysiological roles of MMPs and the best strategies to inhibit their detrimental functions. This review aims to discuss MMPs in preclinical models and human pathologies. We will discuss new biochemical tools to track their proteolytic activity in vivo and ex vivo, in addition to future pharmacological alternatives to inhibit their detrimental functions in diseases. SIGNIFICANCE STATEMENT: Matrix metalloproteinases (MMPs) have been implicated in most inflammatory, autoimmune, cancers, and pathogen-mediated diseases. Initially overlooked, MMP contributions can be both beneficial and detrimental in disease progression and resolution. Thousands of MMP substrates have been suggested, and a few hundred have been validated. After more than 60 years of MMP research, there remain intriguing enigmas to solve regarding their biological functions in diseases.

Established Liposome-Coated IMB16-4 Polymeric Nanoparticles (LNPs) for Increasing Cellular Uptake and Anti-Fibrotic Effects In Vitro

As a global health problem, liver fibrosis still does not have approved treatment. It was proved that N-(3,4,5-trichlorophenyl)-2(3-nitrobenzenesulfonamide) benzamide (IMB16-4) has anti-hepatic fibrosis activity. However, IMB16-4 displays poor water solubility and poor bioavailability. We are devoted to developing biodegraded liposome-coated polymeric nanoparticles (LNPs) as IMB16-4 delivery systems for improving aqueous solubility, cellular uptake, and anti-fibrotic effects. The physical states of IMB16-4−LNPs were analyzed using a transmission electron microscope (TEM), high-performance liquid chromatography (HPLC), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and differential scanning calorimeter (DSC). The results show that IMB16-4−LNPs increased the drug loading compared to liposomes and enhanced cellular uptake behavior compared with IMB16-4−NPs. In addition, IMB16-4−LNPs could repress the expression of hepatic fibrogenesis-associated proteins, indicating that IMB16-4−LNPs exhibited evident anti-fibrotic effects.

Nonalcoholic Steatohepatitis (NASH) and Atherosclerosis: Explaining Their Pathophysiology, Association and the Role of Incretin-Based Drugs

Nonalcoholic steatohepatitis (NASH) is the most severe manifestation of nonalcoholic fatty liver disease (NAFLD), a common complication of type 2 diabetes, and may lead to cirrhosis and hepatocellular carcinoma. Oxidative stress and liver cell damage are the major triggers of the severe hepatic inflammation that characterizes NASH, which is highly correlated with atherosclerosis and coronary artery disease. Regarding drug therapy, research on the role of GLP-1 analogues and DPP4 inhibitors, novel classes of antidiabetic drugs, is growing. In this review, we outline the association between NASH and atherosclerosis, the underlying molecular mechanisms, and the effects of incretin-based drugs, especially GLP-1 RAs, for the therapeutic management of these conditions.

Design of a highly potent GLP-1R and GCGR dual-agonist for recovering hepatic fibrosis

Currently, there is still no effective curative treatment for the development of late-stage liver fibrosis. Here, we have illustrated that TB001, a dual glucagon-like peptide-1 receptor/glucagon receptor (GLP-1R/GCGR) agonist with higher affinity towards GCGR, could retard the progression of liver fibrosis in various rodent models, with remarkable potency, selectivity, extended half-life and low toxicity. Four types of liver fibrosis animal models which were induced by CCl₄, α-naphthyl-isothiocyanate (ANIT), bile duct ligation (BDL) and Schistosoma japonicum were used in our study. We found that TB001 treatment dose-dependently significantly attenuated liver injury and collagen accumulation in these animal models. In addition to decreased levels of extracellular matrix (ECM) accumulation during hepatic injury, activation of hepatic stellate cells was also inhibited via suppression of TGF-β expression as well as downstream Smad signaling pathways particularly in CCl₄-and S. japonicum-induced liver fibrosis. Moreover, TB001 attenuated liver fibrosis through blocking downstream activation of pro-inflammatory nuclear factor kappa B/NF-kappa-B inhibitor alpha (NFκB/IKBα) pathways as well as c-Jun N-terminal kinase (JNK)-dependent induction of hepatocyte apoptosis. Furthermore, GLP-1R and/or GCGR knock-down results represented GCGR played an important role in ameliorating CCl₄-induced hepatic fibrosis. Therefore, TB001 can be used as a promising therapeutic candidate for the treatment of multiple causes of hepatic fibrosis demonstrated by our extensive pre-clinical evaluation of TB001.

Molecular Mechanisms and Potential New Therapeutic Drugs for Liver Fibrosis

Liver fibrosis is the pathological process of excessive extracellular matrix deposition after liver injury and is a precursor to cirrhosis, hepatocellular carcinoma (HCC). It is essentially a wound healing response to liver tissue damage. Numerous studies have shown that hepatic stellate cells play a critical role in this process, with various cells, cytokines, and signaling pathways engaged. Currently, the treatment targeting etiology is considered the most effective measure to prevent and treat liver fibrosis, but reversal fibrosis by elimination of the causative agent often occurs too slowly or too rarely to avoid life-threatening complications, especially in advanced fibrosis. Liver transplantation is the only treatment option in the end-stage, leaving us with an urgent need for new therapies. An in-depth understanding of the mechanisms of liver fibrosis could identify new targets for the treatment. Most of the drugs targeting critical cells and cytokines in the pathogenesis of liver fibrosis are still in pre-clinical trials and there are hardly any definitive anti-fibrotic chemical or biological drugs available for clinical use. In this review, we will summarize the pathogenesis of liver fibrosis, focusing on the role of key cells, associated mechanisms, and signaling pathways, and summarize various therapeutic measures or drugs that have been trialed in clinical practice or are in the research stage.

High throughput interrogation of human liver stellate cells reveals microenvironmental regulation of phenotype

Liver fibrosis is a common feature of progressive liver disease and is manifested as a dynamic series of alterations in both the biochemical and biophysical properties of the liver. Hepatic stellate cells (HSCs) reside within the perisinusoidal space of the liver sinusoid and are one of the main drivers of liver fibrosis, yet it remains unclear how changes to the sinusoidal microenvironment impact HSC phenotype in the context of liver fibrosis. Cellular microarrays were used to examine and deconstruct the impacts of bio-chemo-mechanical changes on activated HSCs in vitro. Extracellular matrix (ECM) composition and stiffness were found to act individually and in combination to regulate HSC fibrogenic phenotype and proliferation. Hyaluronic acid and collagen III promoted elevated collagen I expression while collagen IV mediated a decrease. Previously activated HSCs exhibited reduced lysyl oxidase (Lox) expression as array substrate stiffness increased, with less dependence on ECM composition. Collagens III and IV increased HSC proliferation, whereas hyaluronic acid had the opposite effect. Meta-analysis performed on these data revealed distinct phenotypic clusters (e.g. low fibrogenesis/high proliferation) as a direct function of their microenvironmental composition. Notably, soft microenvironments mimicking healthy tissue (1 kPa), promoted higher levels of intracellular collagen I and Lox expression in activated HSCs, compared to stiff microenvironments mimicking fibrotic tissue (25 kPa). Collectively, these data suggest potential HSC functional adaptations in response to specific bio-chemo-mechanical changes relevant towards the development of therapeutic interventions. These findings also underscore the importance of the microenvironment when interrogating HSC behavior in healthy, disease, and treatment settings. STATEMENT OF SIGNIFICANCE: In this work we utilized high-throughput cellular microarray technology to systematically interrogate the complex interactions between HSCs and their microenvironment in the context of liver fibrosis. We observed that HSC phenotype is regulated by ECM composition and stiffness, and that these phenotypes can be classified into distinct clusters based on their microenvironmental context. Moreover, the range of these phenotypic responses to microenvironmental stimuli is substantial and a direct consequence of the combinatorial pairing of ECM protein and stiffness signals. We also observed a novel role for microenvironmental context in affecting HSC responses to potential fibrosis therapeutics.

New IMB16-4 Nanoparticles Improved Oral Bioavailability and Enhanced Anti-Hepatic Fibrosis on Rats

Liver fibrosis is challenging to treat because of the lack of effective agents worldwide. Recently, we have developed a novel compound, N-(3,4,5-trichlorophenyl)-2(3-nitrobenzenesulfonamido) benzamide referred to as IMB16-4. However, its poor aqueous solubility and poor oral bioavailability obstruct the drug discovery programs. To increase the dissolution, improve the oral bioavailability and enhance the antifibrotic activity of IMB16-4, PVPK30 was selected to establish the IMB16-4 nanoparticles. Drug release behavior, oral bioavailability, and anti-hepatic fibrosis effects of IMB16-4 nanoparticles were evaluated. The results showed that IMB16-4 nanoparticles greatly increased the dissolution rate of IMB16-4. The oral bioavailability of IMB16-4 nanoparticles was improved 26-fold compared with that of pure IMB16-4. In bile duct ligation rats, IMB16-4 nanoparticles significantly repressed hepatic fibrogenesis and improved the liver function. These findings indicate that IMB16-4 nanoparticles will provide information to expand a novel anti-hepatic fibrosis agent.

Thorny ground, rocky soil: Tissue-specific mechanisms of tumor dormancy and relapse

Disseminated tumor cells (DTCs) spread systemically yet distinct patterns of metastasis indicate a range of tissue susceptibility to metastatic colonization. Distinctions between permissive and suppressive tissues are still being elucidated at cellular and molecular levels. Although there is a growing appreciation for the role of the microenvironment in regulating metastatic success, we have a limited understanding of how diverse tissues regulate DTC dormancy, the state of reversible quiescence and subsequent awakening thought to contribute to delayed relapse. Several themes of microenvironmental regulation of dormancy are beginning to emerge, including vascular association, co-option of pre-existing niches, metabolic adaptation, and immune evasion, with tissue-specific nuances. Conversely, DTC awakening is often associated with injury or inflammation-induced activation of the stroma, promoting a proliferative environment with DTCs following suit. We review what is known about tissue-specific regulation of tumor dormancy on a tissue-by-tissue basis, profiling major metastatic organs including the bone, lung, brain, liver, and lymph node. An aerial view of the barriers to metastatic growth may reveal common targets and dependencies to inform the therapeutic prevention of relapse.

Human Liver Stem Cell Transplantation Alleviates Liver Fibrosis in a Rat Model of CCl4-Induced Liver Fibrosis

Background and Objectives

Mesenchymal stem cells (MSCs) elicit therapeutic effects against liver fibrosis in animal models. Human liver stem cells (HLSCs) are cells isolated from human liver tissue that have mesenchymal morphology and express MSC markers. HLSCs also possess intrahepatic stem cell properties. We introduce a rat model of liver fibrosis and trans-portal transplantation of HLSC to demonstrate alleviation of liver fibrosis.

Methods and Results

Liver fibrosis was induced by intraperitoneal injection of Carbon tetrachloride (CCl₄). Sprague Dawley rats underwent simultaneous partial hepatectomy of the left hepatic lobe and HLSC transplantation via the portal vein. Gross appearance of the liver observed following CCl₄ injection showed cholestasis and surface nodularity. Sirius red staining revealed deposition of collagen fibers in the extracellular matrix (ECM). Following HLSC transplantation, human albumin secreting cells were detected by immunohistochemistry in liver specimens. Quantitative measurements of fibrosis area stained by Sirius red were compared between baseline and post-HLSC transplant (1×10⁷ cells) following 10 weeks of CCl₄ treatment liver specimens. Fibrosis area (p<0.05), serum markers of liver inflammation and fibrosis (AST, ALT levels and APRI, p<0.05) significantly decreased from baseline after HLSC transplantation. RNA expression in liver tissues revealed significant decrease in tissue inhibitor of matrix metalloproteinase 1 (TIMP1), TIMP2 expression and increase in hepatocyte growth factor expression following HLSC transplantation (p<0.05).

Conclusions

HLSC transplantation effectively reduced the area of liver fibrosis with increased expression of factors promoting ECM degradation. These findings suggest the potential therapeutic role of HLSCs in various liver diseases presenting with liver fibrosis.

Costunolide Loaded in pH-Responsive Mesoporous Silica Nanoparticles for Increased Stability and an Enhanced Anti-Fibrotic Effect

Liver fibrosis remains a significant public health problem. However, few drugs have yet been validated. Costunolide (COS), as a monomeric component of the traditional Chinese medicinal herb Saussurea Lappa, has shown excellent anti-fibrotic efficacy. However, COS displays very poor aqueous solubility and poor stability in gastric juice, which greatly limits its application via an oral administration. To increase the stability, improve the dissolution rate and enhance the anti-liver fibrosis of COS, pH-responsive mesoporous silica nanoparticles (MSNs) were selected as a drug carrier. Methacrylic acid copolymer (MAC) as a pH-sensitive material was used to coat the surface of MSNs. The drug release behavior and anti-liver fibrosis effects of MSNs-COS-MAC were evaluated. The results showed that MSNs-COS-MAC prevented a release in the gastric fluid and enhanced the dissolution rate of COS in the intestinal juice. At half the dose of COS, MSNs-COS-MAC still effectively ameliorated parenchymal necrosis, bile duct proliferation and excessive collagen. MSNs-COS-MAC significantly repressed hepatic fibrogenesis by decreasing the expression of hepatic fibrogenic markers in LX-2 cells and liver tissue. These results suggest that MSNs-COS-MAC shows great promise for anti-liver fibrosis treatment.

The bright side of fibroblasts: molecular signature and regenerative cues in major organs

Fibrosis is a pathologic process characterized by the replacement of parenchymal tissue by large amounts of extracellular matrix, which may lead to organ dysfunction and even death. Fibroblasts are classically associated to fibrosis and tissue repair, and seldom to regeneration. However, accumulating evidence supports a pro-regenerative role of fibroblasts in different organs. While some organs rely on fibroblasts for maintaining stem cell niches, others depend on fibroblast activity, particularly on secreted molecules that promote cell adhesion, migration, and proliferation, to guide the regenerative process. Herein we provide an up-to-date overview of fibroblast-derived regenerative signaling across different organs and discuss how this capacity may become compromised with aging. We further introduce a new paradigm for regenerative therapies based on reverting adult fibroblasts to a fetal/neonatal-like phenotype.

Wild Bitter Melon Extract Regulates LPS-Induced Hepatic Stellate Cell Activation, Inflammation, Endoplasmic Reticulum Stress, and Ferroptosis

The activation of hepatic stellate cells (HSCs) is a key component of liver fibrosis. Two antifibrosis pathways have been identified, the reversion to quiescent-type HSCs and the clearance of HSCs through apoptosis. Lipopolysaccharide- (LPS-) induced HSCs activation and proliferation have been associated with the development of liver fibrosis. We determined the pharmacological effects of wild bitter melon (WM) on HSC activation following LPS treatment and investigated whether WM treatment affected cell death pathways under LPS-treated conditions, including ferroptosis. WM treatment caused cell death, both with and without LPS treatment. WM treatment caused reactive oxygen species (ROS) accumulation without LPS treatment and reversed the decrease in lipid ROS production in HSCs after LPS treatment. We examined the effects of WM treatment on fibrosis, endoplasmic reticulum (ER) stress, inflammation, and ferroptosis in LPS-activated HSCs. The western blotting analysis revealed that the WM treatment of LPS-activated HSCs induced the downregulation of the connective tissue growth factor (CTGF), α-smooth muscle actin (α-SMA), integrin-β1, phospho-JNK (p-JNK), glutathione peroxidase 4 (GPX4), and cystine/glutamate transporter (SLC7A11) and the upregulation of CCAAT enhancer-binding protein homologous protein (CHOP). These results support WM as an antifibrotic agent that may represent a potential therapeutic solution for the management of liver fibrosis.

Antifibrotic and anthelminthic effect of casticin on Schistosoma mansoni-infected BALB/c mice

BACKGROUND/PURPOSE

Schistosomiasis is an important tropical disease caused by Schistosoma. Although the pathogenesis of liver fibrosis has been intensively studied, the choice of effective treatment is still inadequate. In this study, we aimed to investigate the potential of using Casticin to treat Schistosoma mansoni-induced liver fibrosis.

METHODS

BALB/c mice were divided into three groups - control, infection, and treatment group. The infection and treatment group were percutaneously infected with 100-120 cercariae. Mice from the treatment group were treated with 20 mg/kg/day Casticin for 14 consecutive days to investigate the potential protective effects of Casticin. Mice were sacrificed and were used for histological, RNA, protein, and parasite burden analysis.

RESULTS

Our results showed that hepatic fibrosis was significantly attenuated, as indicated by histology and reduction of fibrotic markers such as collagen AI, transforming growth factor β (TGF-β), and α-smooth muscle actin (α-SMA). Furthermore, Casticin treatment significantly reduced worm burden. Anthelmintic effect of Casticin was also observed by scanning electron microscopy.

CONCLUSION

Collectively, our study suggested that Casticin may be a beneficial candidate in treating S. mansoni infection.

Fibrosis Regression After Eradication of Hepatitis C Virus: From Bench to Bedside

Hepatitis C virus (HCV) infection and its complications have been the major cause of cirrhosis and its complications for several decades in the Western world. Until recently, treatment for HCV with interferon-based regimens was associated with moderate success but was difficult to tolerate. More recently, however, an arsenal of novel and highly effective direct-acting antiviral (DAA) drugs has transformed the landscape by curing HCV in a broad range of patients, including those with established advanced fibrosis, cirrhosis, comorbidities, and even those with complications of cirrhosis. Fibrosis is a dynamic process comprising both extracellular matrix deposition, as well as its degradation. With almost universal sustained virologic response (SVR) (ie, elimination of HCV), it is timely to explore whether HCV eradication can reverse fibrosis and cirrhosis. Indeed, fibrosis in several types of liver disease is reversible, including HCV. However, we do not know with certainty in whom fibrosis regression can be expected after HCV elimination, how quickly it occurs, and whether antifibrotic therapies will be indicated in those with persistent cirrhosis. This review summarizes the evidence for reversibility of fibrosis and cirrhosis after HCV eradication, its impact on clinical outcomes, and therapeutic prospects for directly promoting fibrosis regression in patients whose fibrosis persists after SVR.

Novel IMB16-4 Compound Loaded into Silica Nanoparticles Exhibits Enhanced Oral Bioavailability and Increased Anti-Liver Fibrosis In Vitro

Background: Liver fibrosis, as a common and refractory disease, is challenging to treat due to the lack of effective agents worldwide. Recently, we have developed a novel compound, N-(3,4,5-trichlorophenyl)-2(3-nitrobenzenesulfonamide) benzamide (IMB16-4), which is expected to have good potential effects against liver fibrosis. However, IMB16-4 is water-insoluble and has very low bioavailability. Methods: Mesoporous silica nanoparticles (MSNs) were selected as drug carriers for the purpose of increasing the dissolution of IMB16-4, as well as improving its oral bioavailability and inhibiting liver fibrosis. The physical states of IMB16-4 and IMB16-4-MSNs were investigated using nitrogen adsorption, thermogravimetric analysis (TGA), HPLC, UV-Vis, X-ray diffraction (XRD) and differential scanning calorimetry (DSC). Results: The results show that MSNs enhanced the dissolution rate of IMB16-4 significantly. IMB16-4-MSNs reduced cytotoxicity at high concentrations of IMB16-4 on human hepatic stellate cells LX-2 cells and improved oral bioavailability up to 530% compared with raw IMB16-4 on Sprague–Dawley (SD) rats. In addition, IMB16-4-MSNs repressed hepatic fibrogenesis by decreasing the expression of hepatic fibrogenic markers, including α-smooth muscle actin (α-SMA), transforming growth factor-beta (TGF-β1) and matrix metalloproteinase-2 (MMP2) in LX-2 cells. Conclusions: These results provided powerful information on the use of IMB16-4-MSNs for the treatment of liver fibrosis in the future.

Molecular and cellular mechanisms of liver fibrosis and its regression

Chronic liver injury leads to liver inflammation and fibrosis, through which activated myofibroblasts in the liver secrete extracellular matrix proteins that generate the fibrous scar. The primary source of these myofibroblasts are the resident hepatic stellate cells. Clinical and experimental liver fibrosis regresses when the causative agent is removed, which is associated with the elimination of these activated myofibroblasts and resorption of the fibrous scar. Understanding the mechanisms of liver fibrosis regression could identify new therapeutic targets to treat liver fibrosis. This Review summarizes studies of the molecular mechanisms underlying the reversibility of liver fibrosis, including apoptosis and the inactivation of hepatic stellate cells, the crosstalk between the liver and the systems that orchestrate the recruitment of bone marrow-derived macrophages (and other inflammatory cells) driving fibrosis resolution, and the interactions between various cell types that lead to the intracellular signalling that induces fibrosis or its regression. We also discuss strategies to target hepatic myofibroblasts (for example, via apoptosis or inactivation) and the myeloid cells that degrade the matrix (for example, via their recruitment to fibrotic liver) to facilitate fibrosis resolution and liver regeneration.

Regression of portal hypertension: underlying mechanisms and therapeutic strategies

Portal hypertension is the main non-neoplastic complication of chronic liver disease, being the cause of important life-threatening events including the development of ascites or variceal bleeding. The primary factor in the development of portal hypertension is a pathological increase in the intrahepatic vascular resistance, due to liver microcirculatory dysfunction, which is subsequently aggravated by extra-hepatic vascular disturbances including elevation of portal blood inflow. Evidence from pre-clinical models of cirrhosis has demonstrated that portal hypertension and chronic liver disease can be reversible if the injurious etiological agent is removed and can be further promoted using pharmacological therapy. These important observations have been partially demonstrated in clinical studies. This paper aims at providing an updated review of the currently available data regarding spontaneous and drug-promoted regression of portal hypertension, paying special attention to the clinical evidence. It also considers pathophysiological caveats that highlight the need for caution in establishing a new dogma that human chronic liver disease and portal hypertension is reversible.

You Say You Want a Resolution (of Fibrosis)

In pathological fibrosis, aberrant tissue remodeling with excess extracellular matrix leads to organ dysfunction and eventual morbidity. Diseases of fibrosis create significant global health and economic burdens and are often deadly. Although fibrosis has traditionally been thought of as an irreversible process, a growing body of evidence demonstrates that organ fibrosis can reverse in certain circumstances, especially if an underlying cause of injury can be removed. This body of evidence has uncovered more and more contributors to persistent and nonresolving tissue fibrosis. Here, we review the present knowledge on resolution of organ fibrosis and restoration of near-normal tissue architecture. We emphasize three critical areas of tissue homeostasis that are necessary for fibrosis resolution, namely, the elimination of matrix-producing cells, the clearance of excess matrix, and the regeneration of normal tissue constituents. In so doing, we also highlight how profibrotic pathways interact with one another and where there may be therapeutic opportunities to intervene and remediate pathological persistent fibrosis.

Differential effects of olive oil, soybean oil, corn oil and lard oil on carbon tetrachloride-induced liver fibrosis in mice

Olive oil could attenuate carbon tetrachloride (CCl₄) induced liver fibrosis (LF) in mouse model. The present study aimed to evaluate the effects of other common oils on CCl₄ induced LF. Healthy male ICR mice were administered with CCl₄ intraperitoneally at 2.5 ml/kg twice a week for total 3 weeks. Mice were pre-treated with olive oil, soybean oil, corn oil or lard oil. After treatment, histopathological changes were observed using Masson trichrome staining, and alanine aminotransferase (ALT), aspartate aminotransferase (AST), malondialdehyde (MDA), hydroxyproline (HYP) and triglyceride (TG) were measured by commercial kits. The expression of LF related genes was detected by quantitative real-time PCR. We found that soybean oil or olive oil significantly reduced ALT and AST levels in serum, and MDA, HYP and TG levels in the liver, compared with corn oil or lard oil. Moreover, Masson trichrome staining and real-time PCR showed that the mice treated with CCl₄ dissolved in soybean oil or olive oil had less fibrosis and apoptosis in the liver comparted to the mice treated with CCl₄ dissolved in corn oil or lard oil. In conclusion, soybean oil but not corn or lard oil exerts protective effects against CCl₄ induced LF in mice, possibly due to its antioxidant activity.

Transplantation of Human Amnion Epithelial Cells Improves Endometrial Regeneration in Rat Model of Intrauterine Adhesions

Intrauterine adhesions (IUAs) are characterized by the injury of endometrium due to curettage and/or endometritis. The loss of functional endometrium in uterine cavity usually results in hypomenorrhea, amenorrhea, infertility, and/or recurrent pregnancy loss. Recently, stem cell transplantation has been applied to promote the endometrial regeneration. Human amnion epithelial cells (hAECs) have been shown to have stem cell characteristics. In this study, we found that PKH26-labeled hAECs were mainly distributed in the basal layer of endometrium after transplantation, and hAEC transplantation, including uterine injection and tail vein injection, could increase pregnancy rate and the number of embryos in rat model of IUAs. Moreover, hAEC transplantation was demonstrated to increase the endometrial thickness, promote the proliferation of glands and blood vessels, and decrease fibrotic areas in the endometrium. The immunohistochemical and quantitative polymerase chain reaction analysis showed the upregulated expression of growth factors, such as basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGF), insulin-like growth factor-1 (IGF-1) after hAEC transplantation; and the downregulated expression of collagen type I alpha 1 (COL1A1), tissue inhibitor of metalloproteinase-1 (TIMP-1), and transforming growth factor-β (TGF-β), all of which are associated with the extracellular matrix (ECM) deposition after hAEC transplantation. The mRNA sequencing indicated that platelet-derived growth factor-C (PDGF-C), thrombospondin-1 (THBS1), connective tissue growth factor (CTGF), Wnt5a, and Snai2 were significantly modulated in treatment groups. These results indicate that hAEC transplantation promotes endometrial regeneration and the restoration of fertility in rat model of IUAs.

Chrysophanol Prevents Lipopolysaccharide-Induced Hepatic Stellate Cell Activation by Upregulating Apoptosis, Oxidative Stress, and the Unfolded Protein Response

Hepatic stellate cell (HSC) activation is a vital driver of liver fibrosis. Recent research efforts have emphasized the clearance of activated HSCs by apoptosis, senescence, or reversion to the quiescent state. LPS induces human HSC activation directly and contributes to liver disease progression. Chrysophanol is an anthraquinone with hepatoprotective and anti-inflammatory effects. This study aimed to investigate the pharmacological effects and mechanisms of chrysophanol in an LPS-induced activated rat HSC cell line (HSC-T6). The fibrosis phenotype was identified from the expression of α-smooth muscle actin (α-SMA), connective tissue growth factor (CTGF), and integrin β1 by western blot analysis. We examined DNA fragmentation by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining. We detected the apoptotic markers p53 and cleaved caspase-3 by western blot analysis. Intracellular ROS were labeled with 2′,7′-dichlorofluorescein diacetate (DCF-DA) and the levels were measured by flow cytometry. Finally, we evaluated the ER stress markers binding immunoglobulin protein (BiP) and C/EBP homologous protein (CHOP) by Western blot analysis. Our results showed that chrysophanol decreased HSC-T6 cell viability in LPS-induced activated HSCs. Chrysophanol increased the expression of α-SMA, CTGF, integrin βI, p53, cleaved caspase-3, and DNA fragmentation. Chrysophanol also elevated ROS levels and increased the expression of BiP and CHOP. Pretreatment with chrysophanol prevented LPS-induced HSC-T6 cell activation by upregulating apoptosis, ROS accumulation, unfolded protein response (UPR) activation, and the UPR proapoptotic effect.

TIMP1 preserves the blood-brain barrier through interacting with CD63/integrin 1 complex and regulating downstream FAK/RhoA signaling

Blood-brain barrier (BBB) breakdown and the associated microvascular hyperpermeability are hallmark features of several neurological disorders, including traumatic brain injury (TBI). However, there is no viable therapeutic strategy to rescue BBB function. Tissue inhibitor of metalloproteinase-1 (TIMP1) has been considered to be beneficial for vascular integrity, but the molecular mechanisms underlying the functions of TIMP1 remain elusive. Here, we report that TIMP1 executes a protective role on neuroprotective function via ameliorating BBB disruption in mice with experimental TBI. In human brain microvessel endothelial cells (HBMECs) exposed to hypoxia and inflammation injury, the recombinant TIMP1 (rTIMP1) treatment maintained integrity of junctional proteins and trans-endothelial tightness. Mechanistically, TIMP1 interacts with CD63/integrin β1 complex and activates downstream FAK signaling, leading to attenuation of RhoA activation and F-actin depolymerization for endothelial cells structure stabilization. Notably, these effects depend on CD63/integrin β1 complex, instead of the MMP-inhibitory function. Together, our results identified a novel MMP-independent function of TIMP1 in regulating endothelial barrier integrity. Therapeutic interventions targeting TIMP1 and its downstream signaling may be beneficial to protect BBB function following brain injury and neurological disorders.

Metabolic inflammation as an instigator of fibrosis during non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is characterized by excessive storage of fatty acids in the form of triglycerides in hepatocytes. It is most prevalent in western countries and includes a wide range of clinical and histopathological findings, namely from simple steatosis to steatohepatitis and fibrosis, which may lead to cirrhosis and hepatocellular cancer. The key event for the transition from steatosis to fibrosis is the activation of quiescent hepatic stellate cells (qHSC) and their differentiation to myofibroblasts. Pattern recognition receptors (PRRs), expressed by a plethora of immune cells, serve as essential components of the innate immune system whose function is to stimulate phagocytosis and mediate inflammation upon binding to them of various molecules released from damaged, apoptotic and necrotic cells. The activation of PRRs on hepatocytes, Kupffer cells, the resident macrophages of the liver, and other immune cells results in the production of proinflammatory cytokines and chemokines, as well as profibrotic factors in the liver microenvironment leading to qHSC activation and subsequent fibrogenesis. Thus, elucidation of the inflammatory pathways associated with the pathogenesis and progression of NAFLD may lead to a better understanding of its pathophysiology and new therapeutic approaches.

Targeting Hepatic Stellate Cells for the Treatment of Liver Fibrosis by Natural Products: Is It the Dawning of a New Era?

Liver fibrosis is a progressive liver damage condition that is worth studying widely. It is important to target and alleviate the disease at an early stage before turning into later cirrhosis or liver cancer. There are currently no direct medicines targeting the attenuation or reversal of liver fibrosis, and so there is an urgent need to look into this area. Traditional Chinese Medicine has a long history in using herbal medicines to treat liver diseases including fibrosis. It is time to integrate the ancient wisdom with modern science and technology to look for the best solution to the disease. In this review, the principal concept of the pathology of liver fibrosis will be described, and then some of the single compounds isolated from herbal medicines, including salvianolic acids, oxymatrine, curcumin, tetrandrine, etc. will be discussed from their effects to the molecular mechanism behind. Molecular targets of the compounds are analyzed by network pharmacology approach, and TGFβ/SMAD was identified as the most common pathway. This review serves to summarize the current findings of herbal medicines combining with modern medicines in the area of fibrosis. It hopefully provides insights in further pharmaceutical research directions.

siRNA- and miRNA-based therapeutics for liver fibrosis

Liver fibrosis is a wound-healing process induced by chronic liver injuries, such as nonalcoholic steatohepatitis, hepatitis, alcohol abuse, and metal poisoning. The accumulation of excessive extracellular matrix (ECM) in the liver is a key characteristic of liver fibrosis. Activated hepatic stellate cells (HSCs) are the major producers of ECM and therefore play irreplaceably important roles during the progression of liver fibrosis. Liver fibrogenesis is highly correlated with the activation of HSCs, which is regulated by numerous profibrotic cytokines. Using RNA interference to downregulate these cytokines in activated HSCs is a promising strategy to reverse liver fibrosis. Meanwhile, microRNAs (miRNAs) have also been exploited for the treatment of liver fibrosis. This review focuses on the current siRNA- and miRNA-based liver fibrosis treatment strategies by targeting activated HSCs in the liver.

Dynamic features of liver fibrogenesis and fibrosis resolution in the absence of matrix metalloproteinase‑9

The two‑edged effect of matrix metalloproteinase‑9 (MMP9) makes it difficult to understand its role in liver fibrogenesis and fibrosis resolution. The present study aimed to investigate the dynamic features of liver fibrogenesis and fibrosis resolution in the absence of MMP9. MMP9‑/‑ mice were used to induce liver fibrosis by thioacetamide. The degrees of liver fibrogenesis and fibrosis resolution were designated by the levels of collagen I, III and IV, which were determined via western blotting. Liver injury and the transcriptional levels of MMPs and tissue inhibitor of metalloproteinases (TIMPs) were also determined. It was revealed that, in the absence of MMP9, acute liver injury was attenuated and the expression of collagen was alleviated at the early stage of liver fibrosis, particularly in the first 3 weeks. However, their levels increased to levels as high as those in the control group by week 8. During liver fibrosis resolution, in the absence of MMP9, the ratio of (MMP9 + MMP13)/TIMP1 and the ratio of (MMP2+ MMP14)/TIMP2 were decreased, and the collagen levels were increased. The present study revealed the dynamic features of liver fibrogenesis and fibrosis resolution in the absence of MMP9. The information obtained here will improve current understanding of the effect that MMP9 has in liver fibrogenesis and fibrosis resolution.

"Let my liver rather heat with wine" - a review of hepatic fibrosis pathophysiology and emerging therapeutics

Cirrhosis is characterized by extensive hepatic fibrosis, and it is the 14th leading cause of death worldwide. Numerous contributing conditions have been implicated in its development, including infectious etiologies, medication overdose or adverse effects, ingestible toxins, autoimmunity, hemochromatosis, Wilson’s disease and primary biliary cholangitis to list a few. It is associated with portal hypertension and its stigmata (varices, ascites, hepatic encephalopathy, combined coagulopathy and thrombophilia), and it is a major risk factor for hepatocellular carcinoma. Currently, orthotopic liver transplantation has been the only curative modality to treat cirrhosis, and the scarcity of donors results in many people waiting years for a transplant. Identification of novel targets for pharmacologic therapy through elucidation of key mechanistic components to induce fibrosis reversal is the subject of intense research. Development of robust models of hepatic fibrosis to faithfully characterize the interplay between activated hepatic stellate cells (the principal fibrogenic contributor to fibrosis initiation and perpetuation), hepatocytes and extracellular matrix components has the potential to identify critical components and mechanisms that can be exploited for targeted treatment. In this review, we will highlight key cellular pathways involved in the pathophysiology of fibrosis from extracellular ligands, effectors and receptors, to nuclear receptors, epigenetic mechanisms, energy homeostasis and cytokines. Further, molecular pathways of hepatic stellate cell deactivation are discussed, including apoptosis, senescence and reversal or transdifferentiation to an inactivated state resembling quiescence. Lastly, clinical evidence of fibrosis reversal induced by biologics and small molecules is summarized, current compounds under clinical trials are described and efforts for treatment of hepatic fibrosis with mesenchymal stem cells are highlighted. An enhanced understanding of the rich tapestry of cellular processes identified in the initiation, perpetuation and resolution of hepatic fibrosis, driven principally through phenotypic switching of hepatic stellate cells, should lead to a breakthrough in potential therapeutic modalities.

Apoptotic effects of hsian-tsao (Mesona procumbens Hemsley) on hepatic stellate cells mediated by reactive oxygen species and ERK, JNK, and caspase-3 pathways

The activation of hepatic stellate cells (HSCs) is an important step in the progress of liver fibrosis. Fibrosis can be impeded by HSC reversion to a quiescent state or HSC clearance through apoptosis. To investigate the apoptotic effects of hsian-tsao (Mesona procumbens Hemsl) on human HSCs, the expression levels of cleaved caspase-3, p38, and c-Jun N-terminal kinase (JNK) were assessed using Western blotting, and the caspase-3 activity was measured using caspase-3/CPP32 colorimetric assay kit. Hsian-tsao extract (HTE) increased the activity of caspase-3 and the level of activated caspase-3, indicating the activation of apoptosis. The intracellular reactive oxygen species (ROS) level increased in a dose-dependent manner. This increase was prevented by an antioxidant, suggesting that HTE induces ROS accumulation. In addition, we found that HTE induced the phosphorylation of the mitogen-activated protein kinases JNK and p38. These collective data indicate that HTE induces apoptosis via ROS production through the p38, JNK, and caspase-3-dependent pathways. HTE may decrease HSC activation in liver fibrosis and may have a therapeutic potential.

Functional recovery in photo-damaged human dermal fibroblasts by human adipose-derived stem cell extracellular vesicles

Ultraviolet-B (UVB) irradiation causes imbalance between dermal matrix synthesis and degradation through aberrant upregulation of matrix metalloproteinases (MMPs), which leads to overall skin photoaging. We investigated the effects of extracellular vesicles (EVs) derived from human adipose-derived stem cells (HASCs) on photo-damaged human dermal fibroblasts (HDFs). EVs were isolated from conditioned media of HASCs with tangential flow filtration and characterized using transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA), western blotting, micro RNA (miRNA) arrays, cytokine arrays and liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). The effects of EVs on the UVB-irradiated HDFs were evaluated using scratch assay, ELISA and real-time PCR. Microarrays exhibited that EVs are rich in various miRNAs and proteins, and that these EV contents are linked to a broad range of biological functions, including fibroblast proliferation, UV protection, collagen biosynthesis, DNA repair and cell ageing. A scratch assay showed that HASC-EVs enhanced the migration ability of UVB-irradiated HDFs. Real-time RT-PCR and ELISA analyses revealed that the HASC-derived EVs significantly suppressed the overexpression of MMP-1, -2, -3 and -9 induced by UVB irradiation and enhanced the expression of collagen types I, II, III and V and elastin. In particular, tissue inhibitor of metalloproteinase (TIMP)-1 and transforming growth factor (TGF)-β1, which are important factors involved in MMP suppression and ECM synthesis, were upregulated in EV-treated HDFs after UVB irradiation. Overall results suggest that diverse components that are enriched in HASC-derived EVs could act as a biochemical cue for recovery from skin photoaging.

Compound Danshen Dripping Pill Inhibits Retina Cell Apoptosis in Diabetic Rats

Scope: Diabetic retinopathy (DR) is a severe microvascular complication of diabetes. Previous clinical trials have shown that Compound Danshen Dripping Pill (CDDP) improves DR symptoms. However, the mechanism involved remains unclear.

Procedures: Rats fed a high-fat diet and injected with streptozotocin (STZ) were used as an experimental type 2 diabetes rodent model. CDDP was administered to two groups of diabetic rats at 0.2 and 0.4 g/kg/day via gastric gavage for 12 weeks. After the 12 weeks of treatment, retinal function was evaluated by electroretinography (ERG). Histological staining and TdT-mediated dUTP nick-end labeling (TUNEL) assays were also performed. Retinal genome expression was determined by gene array.

Results: We found that CDDP moderated ERG and histological abnormalities in diabetic rats, independent of blood glucose level. A gene array showed that CDDP changed 262 genes significantly in the diabetic retina. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis indicated that differentially expressed genes in the CDDP-treated groups were involved mainly in the apoptosis pathway. Moreover, CDDP reduced the number of TUNEL-positive cells in the diabetic retinas. CDDP prevented the reduction in Bcl-2 expression and the increase in BCL-2 associated X (Bax) and caspase-3 (Casp3) expression in diabetic rats.

Conclusion: Our results suggest that CDDP exerts its neuroprotective functions by inhibiting cell apoptosis in diabetic rats.

Graphene-Dendrimer Nanostars for Targeted Macrophage Overexpression of Metalloproteinase 9 and Hepatic Fibrosis Precision Therapy

Fibrosis contributes to ∼45% of all deaths in industrialized nations, but no direct antifibrotic therapeutic interventions exist to date. Graphene-based nanomaterials exhibit excellent versatility in electronics, and emerging trends exploit their properties for biomedical applications, especially for drug and gene delivery. We designed constructs of graphene nanostars linked to PAMAM-G5 dendrimer for the selective targeting and delivery of a plasmid expressing the collagenase metalloproteinase 9 under the CD11b promoter into inflammatory macrophages in cirrhotic livers. Graphene nanostars preferentially accumulated in inflammatory macrophages M1 in less than 3 h in a manner unaffected by covalent linkage to dendrimers. Dendrimer-graphene nanostars efficiently delivered the plasmid encoding for metalloproteinase 9 into macrophages, allowing the synthesis and secretion of the metalloproteinase to digest adjacent collagen fibers. In turn, metalloproteinase 9 overexpression promoted the macrophage switch from inflammatory M1 to pro-regenerative M2 in 3 days. This targeted gene therapy reduced selectively and locally the presence of collagen fibers in fibrotic tracts where inflammatory macrophages accumulated in cirrhotic mice without affecting the activation state of hepatic stellate cells. Overall, this treatment significantly reduced hepatic injury and improved liver restoration in mice with liver cirrhosis treated for 10 days. Graphene-dendrimer nanostars targeted the macrophage overexpression of metalloproteinase 9, selectively reducing hepatic fibrosis, and might be a good treatment for diseases associated with fibrosis and inflammatory macrophage accumulation.

The strength of the protein-material interaction determines cell fate

Extracellular matrix (ECM) proteins are key mediators of cell/material interactions. The surface density and conformation of these proteins adsorbed on the material surface influence cell adhesion and the cellular response. We have previously shown that subtle variations in surface chemistry lead to drastic changes in the conformation of adsorbed fibronectin (FN). On poly(ethyl acrylate) (PEA), FN unfolds and displays domains for cell adhesion and FN-FN interaction, whereas on poly(methyl acrylate) (PMA) - with only one methyl group less - FN remains globular as it is in solution. The effect of the strength of the protein/material interaction in cell response, and its relation to protein density and conformation, has received limited attention so far. In this work, we used FN-functionalized AFM cantilevers to evaluate, via force spectroscopy, the strength of interaction between fibronectin and the underlying polymer which controls FN conformation (PEA and PMA). We found that the strength of FN/PEA interaction is significantly higher than FN/PMA, which limits the mobility of FN layer on PEA, reduces the ability of cells to mechanically reorganize FN and then leads to enhanced proteolysis and degradation of the surrounding matrix with compromised cell viability. By contrast, both PEA and PMA support cell adhesion when FN density is increased and also in the presence of serum or other serum proteins, including vitronectin (VN) and bovine serum albumin (BSA), which provide a higher degree of mobility to the matrix.

STATEMENT OF SIGNIFICANCE

The identification of parameters influencing cell response is of paramount importance for the design of biomaterials that will act as synthetic scaffolds for cells to anchor, grow and, eventually, become specialised tissues. Cells interact with materials through an intermediate layer of proteins adsorbed on the material surface. It is known that the density and conformation of these proteins determine cell behaviour. Here we show that the strength of protein/material interactions, which has received very limited attention so far, is key to understand the cellular response to biomaterials. Very strong protein/material interactions reduce the ability of cells to mechanically reorganize proteins at the material interface which results in enhanced matrix degradation, leading ultimately to compromised cell viability.

Matrix metalloproteinase targeted peptide vesicles for delivering anticancer drugs

A matrix metalloproteinase (MMP) targeted tetrapeptide vesicle has been designed and developed, which strongly binds at a MMP9 enzymatic site. Interestingly, it has a propensity to encapsulate and deliver the doxorubicin drug specifically to the cancer cell, induces superior apoptotic death, and inhibits the metastatic cancer cell migration and growth of multicellular 3D spheroids.