Soluble egg antigens of Schistosoma japonicum induce senescence in activated hepatic stellate cells by activation of the STAT3/p53/p21 pathway

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.

rSjP40 Inhibited the Activity of Collagen Type I Promoter via Ets-1 in HSCs

Liver fibrosis is a severe disease characterized by excessive deposition of extracellular matrix (ECM) components in the liver. Activated hepatic stellate cells (HSCs) are a major source of ECM and a key regulator of liver fibrosis. Collagen type I alpha I (COL1A1) is one of the main components of ECM and is a major component in fibrotic tissues. Previously, we demonstrated that soluble egg antigen from Schistosoma japonicum could inhibit the expression of COL1A1 in activated HSCs. In addition, studies have found that Ets proto-oncogene 1 (Ets-1) suppresses the production of ECM by down-regulating matrix related genes such as COL1A1 induced by transforming growth factor β, and ultimately inhibits liver fibrosis. In this study, the major aim was to investigate the effect and mechanism of Ets-1 on inhibiting COL1A1 gene promoter activity in HSCs by recombinant Schistosoma japonicum protein P40 (rSjP40). We observed the rSjP40 inhibited the expression of COL1A1 by inhibiting the activity of the COL1A1 promoter, and the core region of rSjP40 acting on COL1A1 promoter was located at -1,722/-1,592. In addition, we also demonstrated that rSjP40 could promote the expression of Ets-1, and Ets-1 has a negative regulation effect on the COL1A1 promoter in human LX-2 cells. These data suggest that rSjP40 might inhibit the activity of COL1A1 promoter and inhibit the activation of HSCs by increasing the expression of transcription factor Ets-1, which will provide a new experimental basis for the prevention and treatment of liver fibrosis.

The role of let-7b in the inhibition of hepatic stellate cell activation by rSjP40

BACKGROUND

Hepatic stellate cells (HSCs) are one of the main cell types involved in liver fibrosis induced by many factors, including schistosomes. Previous studies in our lab have shown that recombinant P40 protein from Schistosoma japonicum (rSjP40) can inhibit HSC activation in vitro. Let-7b is a member of the let-7 microRNA family and plays an inhibitory role in a variety of diseases and inflammatory conditions. In this study, we investigated the role of let-7b in the inhibition of HSC activation by rSjP40.

METHODS

Expression of let-7b was detected by quantitative real-time PCR. A dual luciferase assay was used to confirm direct interaction between let-7b and collagen I. We also used western blot to assess protein levels of TGFβRI and collagen type I α1 (COL1A1).

RESULTS

We found that rSjP40 up-regulates expression of let-7b in HSCs. Let-7b inhibits collagen I expression by directly targeting the 3'UTR region of the collagen I gene. Furthermore, we discovered that let-7b inhibitor partially restores the loss of collagen I expression caused by rSjP40.

CONCLUSION

Our research clarifies the role of let-7b in the inhibition of HSC activation by rSjP40 and will provide new insights and ideas for the inhibition of HSC activation and treatment of liver fibrosis.

Schistosoma antigens as activators of inflammasome pathway: from an unexpected stimulus to an intriguing role

Parasites of the genus Schistosoma are organisms capable of living for decades within the definitive host. They interfere with the immune response by interacting with host's receptors. In this review, we discuss from the first reports to the most recent discoveries regarding the ability of Schistosoma antigens in triggering intracellular receptors and inducing inflammasome activation.

Sja-miR-71a in Schistosome egg-derived extracellular vesicles suppresses liver fibrosis caused by schistosomiasis via targeting semaphorin 4D

Schistosomiasis is characterized by liver fibrosis, and studies have indicated that Schistosoma japonicum (S. japonicum) eggs can limit the progression of liver fibrosis. However, the detailed molecular mechanisms are yet unclear. Extracellular vesicles (EVs) contain a selection of miRNAs for long-distance exchange of information and act as an important pathway for host-parasite communication. This study aimed to explore the potential role of S. japonicum egg-derived EVs and its key miRNA in liver fibrosis. Herein, we found that S. japonicum egg-derived EVs can inhibit the activation of hepatic stellate cells, which is mediated via the high expression of Sja-miR-71a. Sja-miR-71a in EVs attenuates the pathological progression and liver fibrosis in S. japonicum infection. Sja-miR-71a inhibiting TGF-β1/SMAD and interleukin (IL)-13/STAT6 pathways via directly targeting semaphorin 4D (Sema4D). In addition, Sja-miR-71a can also suppress liver fibrosis by regulating Th1/Th2/Th17 and Treg balance. This study contributes to further understanding of the molecular mechanisms underlying Schistosoma-host interactions, and Sema4D may be a potential target for schistosomiasis liver fibrosis treatment.

MicroRNA-708 represses hepatic stellate cells activation and proliferation by targeting ZEB1 through Wnt/β-catenin pathway

Liver fibrosis is caused by a sustained wound healing response to chronic liver injury, and the activation of insubstantial hepatic stellate cells (HSCs) is the key process involved. The progression of liver fibrosis may be attenuated by suppressing activation and proliferation of the HSCs. MicroRNA (miRNA) have emerged as major players in governing fundamental biological processes through multiple mechanisms MiR-708 is known to inhibit the development of hepatocellular carcinoma. However, whether miR-708 can function as a transcriptional regulator in liver fibrosis remains unclear. Our study demonstrated that miR-708 expression was inhibited in fibrotic liver tissues and in activated HSCs, accompanied by an increase of the Zinc finger E-box binding homeobox 1 (ZEB1) level. Besides, overexpression of miR-708 and silencing of ZEB1 inhibited the activation and proliferation of LX-2 cells. While knockdown of miR-708 or overexpression of ZEB1 showed reversed results. Further, dual luciferase reporter assays showed that miR-708 directly targeted ZEB1 in vitro. Interestingly, ZEB1 was found to be involved in HSCs by regulating Wnt/β-catenin signaling pathway. Together, our data showed that miR-708 may be a potential therapeutic target in liver fibrosis therapy.

SOCS1: phosphorylation, dimerization and tumor suppression

Suppressor of cytokine signaling (SOCS) family members are upregulated following JAK-STAT pathway activation by cytokines. SOCS proteins are recognized inhibitors of cytokine signaling playing roles in cell growth and differentiation. Moreover, SOCS1 and SOCS3 have been shown to be involved in tumor suppression through their ability to interact with p53 leading to the activation of its transcriptional program and showing the implication of SOCS family members in the regulation of apoptosis, ferroptosis and senescence. More recently, we demonstrated that the SRC family of non-receptor tyrosine kinases (SFK) can phosphorylate SOCS1 leading to its homodimerization and inhibiting its interaction with p53. Then, we reactivated the SOCS1-p53 tumor suppressor axis with the SFK inhibitor dasatinib in combination with the p53 activating compound PRIMA. This work suggests new avenues for cancer treatment and leaves open several new questions that deserve to be addressed.

Astragaloside IV regulates NF-κB-mediated cellular senescence and apoptosis of hepatic stellate cells to suppress PDGF-BB-induced activation

Activated hepatic stellate cells (HSCs) are the principal effectors during hepatic fibrosis, which is characterized by the accumulation of extracellular matrix. Therefore, present therapies and investigations into hepatic fibrosis mainly focus on the suppression of activated HSCs. Astragaloside IV (ASIV) is an effective constituent extracted from the plant Astragalus membranaceus and has exhibited anti-fibrotic properties in hepatic fibrosis. However, its protective mechanism against hepatic fibrosis is not fully understood. The present study aimed to investigate the mechanistic role of ASIV on rat HSC-T6 cells activated with platelet-derived growth factor (PDGF)-BB. HSC-T6 cells were activated using PDGF-BB and subsequently treated with ASIV (final concentrations of 20 and 40 µg/ml) for 48 h. ASIV treatment decreased the expression of α1 type I collagen, α-smooth muscle actin and fibronectin on mRNA and protein levels, suggesting that ASIV suppresses PDGF-BB-induced HSC-T6 activation. Senescence-associated β-galactosidase activity, p21, high-mobility group AT-hook 1 and p53, common biomarkers of senescence, were upregulated by ASIV treatment. In addition, the expression of telomerase reverse transcriptase was reduced. ASIV promoted apoptosis of PDGF-BB-activated HSC-T6 cells. The NF-κB signaling pathway, which controls cellular senescence and apoptosis, was demonstrated to be stimulated by ASIV by increasing p65, p52, p50 and inhibitor of NF-κB kinase α expression levels, and by suppressing the expression of NF-κB inhibitor α. Taken together, these results demonstrated that ASIV promoted cellular senescence and apoptosis by activating the NF-κB pathway to suppress PDGF-BB-induced HSC-T6 activation; with potential implications for the treatment of hepatic fibrosis.

rSJYB1 inhibits collagen type I protein expression in hepatic stellate cells via down-regulating activity of collagen α1 (I) promoter

YB1 is a negative regulator in liver fibrosis. We wondered whether SJYB1, a homologous protein of YB1 from Schistosoma japonicum, has an effect on liver fibrosis in vitro. Recombinant SJYB1 (rSJYB1) protein was expressed in a bacterial system and purified by Ni‐NTA His·Bind Resin. A human hepatic stellate cell line, the LX‐2 cell line, was cultured and treated with rSJYB1. The role of rSJYB1 on LX‐2 cells was then analysed by Western blot and luciferase assay. We succeeded in expressing and purifying SJYB1 in a bacterial system and the purified rSJYB1 could be recognized by S japonicum‐infected rabbit sera. Western bolt analysis showed that rSJYB1 inhibited the expression of collagen type I, but had little effect on α‐smooth muscle actin (α‐SMA). Further analysis revealed that rSJYB1 inhibited the activity of collagen α1 (I) (COL1A1) promoter and functioned at −1592/−1176 region of COL1A1 promoter. Our data demonstrate that rSJYB1‐mediated anti‐fibrotic activity involves inhibiting the activity of COL1A1 promoter and subsequently suppressing the expression of collagen type I in hepatic stellate cells.

Schistosoma japonicum soluble egg antigen inhibits TNF-α-induced IL-34 expression in hepatic stellate cells

Hepatic fibrosis is characterized by the activation of the main collagen-producing cells of the liver, hepatic stellate cells, and is associated with inflammation. Although the involvement of numerous inflammatory cytokines has been reported, IL-34 in particular has recently been identified as a profibrotic factor in the development of hepatic fibrosis. Previous studies have found that schistosome eggs can lead to transcriptional downregulation of fibrosis-associated genes, and based on this evidence, we attempted to investigate whether or not IL-34 is regulated by soluble egg antigen (SEA). Our findings testified that SEA inhibited TNF-α-induced expression of IL-34 at both the mRNA and protein levels. Furthermore, results from reporter assays and qPCR experiments demonstrated that SEA impaired the activation of NF-κB triggered by TNF-α, as well as the transcription of downstream genes. More importantly, SEA decreased the phosphorylation and degradation of IκBα induced by TNF-α, two events that are hallmarks of canonical NF-κB activation. In conclusion, our results suggest that, in hepatic stellate cells, SEA impairs NF-κB activation and thereby inhibits TNF-α-induced IL-34 expression. These findings reveal a previously unidentified target and signaling pathway that support SEA's involvement in hepatic fibrosis and provide a new clue to guide ongoing research into the anti-fibrotic effects of SEA.

CD276 (B7-H3) Maintains Proliferation and Regulates Differentiation in Angiogenic Function in Late Endothelial Progenitor Cells

Endothelial progenitor cells (EPCs) provide an important source of recovery from blood vessel dysfunction. Late EPCs (LEPCs) are circulating blood cells that are capable of promoting vascular repair. Using transcriptome analysis, we identified distinctive LEPC profiles and found that CD276 (B7-H3) mRNA is strongly expressed in LEPCs. CD276 protein is present abundantly on the cell surface of LEPC when analyzed by fluorescence-activated cell sorter and immunocytochemistry. CD276, a B7 family member, is a type I transmembrane glycoprotein. The role of CD276 in LEPCs remains unknown. CD276 knockdown by lentivirus transduction in LEPCs significantly decreased proliferation and increased apoptosis of LEPCs in vitro. After CD276 silencing, the cell cycle of LEPCs was prone to remain at the G0/G1 phase, and the cell migration rates as well as transwell and wound-healing migration were decreased. CD276 knockdown in LEPCs increased the G1 phase regulators cyclin D2/D3/E1-cyclin-dependent kinases (CDK2/4/6), but decreased the S-G2-M phase regulators cyclin A/B-CDK1. However, LEPCs with CD276 knockdown resulted in increased tube formation in vitro and angiogenesis in a Matrigel plug assay in vivo. FoxC1/C2, an upstream signal of Notch in arterial cell proliferation, and Hey1/2, which is known to promote arterial differentiation in the vasculature, were upregulated in CD276 knockdown LEPCs. In LEPCS, CD276 has a positive effect on proliferation and migration of endothelial cells, but negative effects on angiogenesis, particularly endothelial cell differentiation. Our data indicate, for therapeutic purpose, that CD276 can be used to acquire and maintain cell populations of LEPCs and blocking CD276 will promote angiogenetic differentiation. We found that CD276 (B7-H3) is enriched on the cell membrane of LEPCs. CD276 knockdown reduced proliferation and migration of LEPCs by increasing cell cycle inhibitors such as p21^cip1 and pRb and decreasing pErk1/2 and pAkt but promoted angiogenesis and endothelial cell differentiation by elevating vascular endothelial growth factor-vascular endothelial growth factor receptor 1 and p-p38. Stem Cells 2019;37:382-394.

MicroRNA-145 induces the senescence of activated hepatic stellate cells through the activation of p53 pathway by ZEB2

Activation of quiescent hepatic stellate cells (HSCs) is the major event in liver fibrosis, along with enhancement of cell proliferation and overproduction of extracellular matrix. Recent findings suggest that senescence of activated HSCs might limit the development of liver fibrosis. The p53, a guardian of the genome is associated with liver fibrosis, has been shown to regulate HSCs senescence. In this study, we report that microRNA-145 (miR-145) and p53 were downregulated in vivo and in vitro, concomitant with the enhanced expression of zinc finger E-box binding homeobox 2 (ZEB2). In addition, overexpression of miR-145 and p53 led to upregulation of the number of senescence-associated β-galactosidase-positive HSCs and the expression of senescence markers p16 and p21, along with the reduced abundance of HSC activation markers α-smooth muscle actin and type I collagen in activated HSCs. Furthermore, silencing of ZEB2 promoted senescence of activated HSCs. Moreover, we also demonstrated that miR-145 specifically targeted the 3'-untranslated regions of ZEB2. In vitro promoter regulation studies show that ZEB2 could bind to the E-box of the p53 promoter as well as inhibit its promoter activity and thus suppress the expression of p53, which in turn repressed activated HSCs senescence. Taken together, our results describe a novel miR-145-ZEB2-p53 regulatory line might participate in the senescence of activated HSCs and might carry potential therapeutic targets for restraining liver fibrosis.

rSjP40 suppresses hepatic stellate cell activation by promoting microRNA-155 expression and inhibiting STAT5 and FOXO3a expression

Activation of hepatic stellate cells (HSCs) is the central event of the evolution of hepatic fibrosis. Schistosomiasis is one of the pathogenic factors which could induce hepatic fibrosis. Previous studies have shown that recombinant Schistosoma japonicum egg antigen P40 (rSjP40) can inhibit the activation and proliferation of HSCs. MicroRNA‐155 is one of the multifunctional noncoding RNA, which is involved in a series of important biological processes including cell development, proliferation, differentiation and apoptosis. Here, we try to observe the role of microRNA‐155 in rSjP40‐inhibited HSC activation and explore its potential mechanisms. We found that microRNA‐155 was raised in rSjP40‐treated HSCs, and further studies have shown that rSjP40 enhanced microRNA‐155 expression by inhibiting STAT5 transcription. Up‐regulated microRNA‐155 can down‐regulate the expression of FOXO3a and then participate in rSjP40‐inhibited expression of α‐smooth muscle actin (α‐SMA) and collagen I. Furthermore, we observed microRNA‐155 inhibitor could partially restore the down‐regulation of FOXO3a, α‐SMA and collagen I expression in LX‐2 cells induced by rSjP40. Therefore, our research provides further insight into the mechanism by which rSjP40 could inhibit HSC activation via miR‐155.

Recombinant SjP40 protein enhances p27 promoter expression in hepatic stellate cells via an E2F1-dependent mechanism

The p27 protein plays a critical role in cell cycle arrest. Our previous studies have demonstrated that recombinant P40 protein from Schistosoma japonicum (rSjP40) could induce G1 phase arrest of cell cycle. We, therefore, attempted to observe the effect of rSjP40 on p27 promoter activity in LX-2 cells and to explore its potential mechanisms in this study. Using both Western blot and dual-luciferase reporter assay, we demonstrated that rSjP40 could enhance the expression of p27 in LX-2 cells. Results obtained using truncated fragments of p27 promoter showed that rSjP40 increased p27 promoter activity in LX-2 cells, mainly via some transcription factors that bind to the -1740/-873 region of p27 promoter. Further studies confirmed that the enhancement of p27 promoter activity induced by rSjP40 was related to E2F1 in LX-2 cells. Transfection of siRNA of E2F1 could also restore the effect of rSjP40 on expression of p27 and partially on α-SMA. Therefore, our study provided further insights into the mechanism by which rSjP40 induces LX-2 cell cycle arrest at G1 phase and inhibits HSC activation. Our results provide basis for future study of the blocking effect of rSjP40 in liver fibrosis.

Schistosome-Induced Fibrotic Disease: The Role of Hepatic Stellate Cells

Hepatic fibrosis is a common pathology in various liver diseases. Hepatic stellate cells (HSCs) are the main cell type responsible for collagen deposition and fibrosis formation in the liver. Schistosomiasis is characterised by granulomatous fibrosis around parasite eggs trapped within the liver and other host tissues. This response is facilitated by the recruitment of immune cells and the activation of HSCs. The interactions between HSCs and schistosome eggs are complex and diverse, and a better understanding of these interactions could lead to improved resolution of fibrotic liver disease, including that associated with schistosomiasis. Here, we discuss recent advances in HSC biology and the role of HSCs in hepatic schistosomiasis.

Molecular interplays in hepatic stellate cells: apoptosis, senescence, and phenotype reversion as cellular connections that modulate liver fibrosis

Liver fibrosis is a pathophysiological process correlated with intense repair and cicatrization mechanisms in injured liver, and over the past few years, the characterization of the fine-tuning of molecular interconnections that support the development of liver fibrosis has been investigated. In this cellular process, the hepatic stellate cells (HSCs) support the organ fibrogenesis. The HSCs are found in two distinct morpho-physiological states: quiescent and activated. In normal liver, most HSCs are found in quiescent state, presenting a considerable amount of lipid droplets in the cytoplasm, while in injured liver, the activated phenotype of HSCs is a myofibroblast, that secrete extracellular matrix elements and contribute to the establishment of the fibrotic process. Studies on the molecular mechanisms by which HSCs try to restore their quiescent state have been performed; however, no effective treatment to reverse fibrosis has been so far prescribed. Therefore, the elucidation of the cellular and molecular mechanisms of apoptosis, senescence, and the cell reversion phenotype process from activate to quiescent state will certainly contribute to the development of effective therapies to treat hepatic fibrosis. In this context, this review aimed to address central elements of apoptosis, senescence, and reversal of HSC phenotype in the control of hepatic fibrogenesis, as a guide to future development of therapeutic strategies.

Lyn kinase enhanced hepatic fibrosis by modulating the activation of hepatic stellate cells

The non-selectivity of tyrosine kinase inhibitors is the leading cause of drug withdrawals, and limits their application in anti-fibrosis. The role of Src tyrosine kinase Lyn in hepatic fibrosis remains elusive. In this study, we aimed to elucidate the role of Lyn kinase in the pathogenesis of hepatic fibrosis. Through examining Lyn-transgenic (Lyn TG) mice treated with CCl4 (carbon tetrachloride), we determined whether Lyn kinase is involved in the pathogenesis of hepatic fibrosis. On top of that, we also investigated the role of Lyn in the activation of hepatic stellate cells (HSCs) in vitro. Here, we showed that Lyn kinase was highly expressed in liver fibrosis upon CCl4 treatment. Meanwhile, Lyn TG mice showed that perivascular infiltration of mononuclear cells, and the markers of liver injury and hepatocytes apoptosis were significantly increased in liver tissue after CCl4 treatment. In comparison with wild-type (WT) mice after CCl4 treatment, we found that the fibrotic score in liver tissues of Lyn TG mice with the same treatment went up dramatically, so did the gene expression of fibrotic markers. In addition, over-expression of Lyn kinase drastically promoted the expression of HSCs activation markers in vivo or in vitro. Additionally, the Src-specific inhibitor PP2 significantly suppressed the increased expression of integrin αvβ3 in TGF-β1-induced HSCs, and PP2 further induced HSC apoptosis in TGF-β1-treated cells. These results collectively indicated that Lyn kinase is implicated in the pathogenesis of hepatic fibrosis through the modulating of HSC activation.

Egg antigen p40 of Schistosoma japonicum promotes senescence in activated hepatic stellate cells via SKP2/P27 signaling pathway

Schistosomiasis is characterized by egg deposition, granulomatous inflammatory reaction and then subsequent hepatic fibrosis formation. Activated HSCs are regarded as the main effector cells in the progression of liver fibrosis and induction of senescence in hepatic stellate cells (HSCs) is vital to the reversion of hepatic fibrosis. Our previous work has showed that S. japonicum egg antigen p40 (Sjp40) could promote HSCs senescence via a STAT3/p53/p21 mechanism. In this paper, the major aim was to explore whether there are other signaling pathways in the process of Sjp40-induced HSCs aging and the underlying effect of SKP2/P27 signal pathway in this procedure. We observed the Sjp40-induced decrease of α-SMA and the senescence of LX-2 cells, and Sjp40 could upregulate P27 and downregulate the protein level of SKP2. The senescence induced by Sjp40 might be reversed in LX-2 cells that treated with P27-specific siRNA or with SKP2-special over-expression plasmid. In addition, we also demonstrated that the decreased expression of P-Rb and α-SMA induced by Sjp40 were partly restored by SKP2-overexpression. These data suggest that Sjp40 might inhibit HSCs activation by promoting cellular senescence via SKP2/P27 signaling pathway, which put forward novel mechanism in the treatment of liver fibrosis.

Modulation of hepatic stellate cells and reversibility of hepatic fibrosis

Hepatic fibrosis (HF) is the pathological component of a variety of chronic liver diseases. Hepatic stellate cells (HSC) are the main collagen-producing cells in the liver and their activation promotes HF. If HSC activation and proliferation can be inhibited, HF occurrence and development can theoretically be reduced and even reversed. Over the past ten years, a number of studies have addressed this process, and here we present a review of HSC modulation and HF reversal.

Soluble Egg Antigens of Schistosoma japonicum Induce Senescence of Activated Hepatic Stellate Cells by Activation of the FoxO3a/SKP2/P27 Pathway

BACKGROUND

Liver fibrosis was viewed as a reversible process. The activation of hepatic stellate cells (HSCs) is a key event in the process of liver fibrosis. The induction of senescence of HSCs would accelerate the clearance of the activated HSCs. Previously, we demonstrated that soluble egg antigens (SEA) of Schistosoma japonicum promoted the senescence of HSCs via STAT3/P53/P21 pathway. In this paper, our study was aimed to explore whether there are other signaling pathways in the process of SEA-induced HSCs aging and the underlying effect of SKP2/P27 signal on senescent HSCs.

METHODOLOGY/PRINCIPAL FINDINGS

Human hepatic stellate cell line, LX-2 cells, were cultured and stimulated with SEA. Western blot and cellular immunofluorescence analysis were performed to determine the expression of senescence-associated protein, such as P27, SKP2 and FoxO3a. Besides, RNA interfering was applied to knockdown the expression of related protein. The senescence of HSCs was determined by senescence-associated β-gal staining. We found that SEA increased the expression of P27 protein, whereas it inhibited the expression of SKP2 and FoxO3a. Knockdown of P27 as well as overexpression of SKP2 both suppressed the SEA-induced senescence of HSCs. In addition, the nuclear translocation of FoxO3a from the nucleus to the cytoplasm was induced by SEA stimulation.

CONCLUSIONS/SIGNIFICANCE

The present study demonstrates that SEA promotes HSCs senescence through the FoxO3a/SKP2/P27 pathway.

STAT3 Inhibition Suppresses Hepatic Stellate Cell Fibrogenesis: HJC0123, a Potential Therapeutic Agent for Liver Fibrosis

Hepatic Stellate Cells (HSCs) are the major source of the excessive extracellular matrix (ECM) production that replaces liver parenchyma with fibrous tissue during liver fibrosis. The signal transducer and activator of transcription 3 (STAT3) promotes HCSs survival, proliferation, and activation contributing to fibrogenesis. We have previously used a fragment-based drug design approach and have discovered a novel STAT3 inhibitor, HJC0123. Here, we explored the biological effects of HJC0123 on the fibrogenic properties of HSCs. HJC0123 treatment resulted in the inhibition of HSCs proliferation at submicromolar concentrations. HJC0123 reduced the phosphorylation, nuclear translocation, and transcriptional activity of STAT3. It decreased the expression of STAT3-regulated proteins, induced cell cycle arrest, promoted apoptosis and downregulated SOCS3. HJC0123 treatment inhibited HSCs activation and downregulated ECM protein fibronectin and type I collagen expression. In addition, HJC0123 increased IL-6 production and decreased TGF-β induced Smad2/3 phosphorylation. These results demonstrate that HJC0123 represents a novel STAT3 inhibitor that suppresses the fibrogenic properties of HSCs, suggesting its therapeutic potential in liver fibrosis.