S100A4 promotes liver fibrosis via activation of hepatic stellate cells

Vincamine ameliorates hepatic fibrosis via inhibiting S100A4-mediated farnesoid X receptor activation: based on liver microenvironment and enterohepatic circulation dependence

BACKGROUND AND PURPOSE

Vincamine has extensive biological and pharmaceutical activity. We examined the hepatoprotective effects and mechanisms by which vincamine suppresses hepatic fibrosis.

EXPERIMENTAL APPROACH

Hepatic stellate cells (HSCs), TGF-β stimulated, were cultured with either vincamine, farnesoid X receptor (NR1H4; FXR) agonist or antagonist. Further, C57BL/6 mice were given thioacetamide (TAA) to induce hepatic fibrosis and subsequently treated with vincamine or curcumin.

KEY RESULTS

Vincamine regulated the deposition of extracellular matrix (ECM), inflammatory factors and S100A4, and up-regulated FXR and TGR5 (GPBA receptor) in activated HSCs, by activating FXR. FXR deficiency blocked vincamine effect on FXR, TGR5, α-smooth muscle actin (α-SMA) and IL1R1 in activated LX-2 cells. Vincamine corrected ECM imbalance, inflammatory secretion and FXR/TGR5 down-regulation in activated LX-2 cells with stimulating medium from LPS-primed THP-1 cells. S100A4 deficiency increased FXR and TGR5, and decreased IL-1β expression in activated THP-1. Further, S100A4 deficiency in activated macrophages could elevate FXR and TGR5 expression in activated LX-2, strengthening the impact of vincamine on α-SMA and IL-1β expression. Further, vincamine reduced serum ALT/AST levels, liver and intestinal histopathological changes, and caused ECM accumulation and protected the intestinal barrier in thioacetamide-induced hepatic fibrosis mice. Vincamine decreased inflammatory factors e.g. caspase 1 and IL-1β, and inhibited the S100A4-mediated FXR-TGR5 pathway.

CONCLUSION AND IMPLICATIONS

Vincamine significantly reverses hepatic fibrosis via inhibiting S100A4 involved in the crosstalk between macrophages and HSCs, and by activating the FXR-TGR5 pathway. Targeting the S100A4-mediated FXR dependence on modulating the liver environment may be the key target of vincamine in inhibiting hepatic fibrosis.

Identification of regulatory cell death-related genes during MASH progression using bioinformatics analysis and machine learning strategies

Background

Metabolic dysfunction-associated steatohepatitis (MASH) is becoming increasingly prevalent. Regulated cell death (RCD) has emerged as a significant disease phenotype and may act as a marker for liver fibrosis. The present study aimed to investigate the regulation of RCD-related genes in MASH to elucidate the role of RCD in the progression of MASH.

Methods

The gene expression profiles from the GSE130970 and GSE49541 datasets were retrieved from the Gene Expression Omnibus (GEO) database for analysis. A total of 101 combinations of 10 machine learning algorithms were employed to screen for characteristic RCD-related differentially expressed genes (DEGs) that reflect the progression of MASH. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were conducted to explore the enrichment pathways and functions of the feature genes. we performed cell classification analysis to investigate immune cell infiltration. Consensus cluster analysis was performed to identify MASH subtypes associated with RCD. The GSE89632 dataset was utilized to analyze the correlation of characteristic genes with clinical features of MASH. The DGIdb database was employed to screen for potential therapeutic drugs and compounds targeting the feature genes. In addition, we established mouse liver fibrosis models induced by methionine-choline-deficient (MCD) diet or CCl4 treatment, and further validated the expression of characteristic genes through quantitative real-time PCR (q-PCR). Lastly, we knocked down EPHA3 in LX2 cells to explore its effect on TGFb-induced activation of LX2 cells.

Results

This study discovered a total of 11 RCD-associated DEGs, which predicted the progression of MASH. Advanced MASH has higher levels of immune cell infiltration and is significantly correlated with the RCD-related DEGs expression. MASH can be classified into two subtypes, cluster 1 and cluster 2, based on these feature genes. Compared with cluster 1, cluster 2 has highly expressed RCD-related DEGs, shows an increase in the degree of fibrosis. Furthermore, We discovered that the expression levels of feature genes were positively correlated with AST and ALT levels. Subsequently, We also evaluated the expression of these 11 feature genes in the liver tissues of mice with fibrosis induced by MCD or CCl4, and the results suggested that these genes may be involved in the development of fibrosis. WB results showed that the protein level of EPHA3 significantly increased in both mouse models of liver fibrosis. In vitro, we observed that knocking down EPHA3 in LX2 cells significantly inhibited the activation of the TGF-β/Smad3 signaling pathway.

Conclusion

Our study sheds light on the fact that RCD contribute to the progression of MASH, high lighting potential therapeutic targets for treating this disease.

Molecular dissection of tendon development and healing: Insights into tenogenic phenotypes and functions

Tendon is a dense connective tissue that transmits contraction forces from skeletal muscles to bones. Adult tendon injury is a significant clinical problem because it occurs frequently with a high recurrence rate, and damaged tendon is rarely restored to full function. The main barrier to improving recovery outcomes is our incomplete understanding of the molecular mechanisms underlying the biological alterations following tendon injury in vivo. In this review, we specifically highlight the cellular dynamism of fibrotic tendon wound healing and the roles of mechanical loading. In particular, we document how tendon stem/progenitor cells expressing the tendon-specific transcription factor Scleraxis (Scx) play a role in fibrotic tendon wound healing, and describe novel experimental systems such as lineage cell tracing and single-cell analysis, both of which can shed light on tendon cell behavior and fate decisions during the tendon wound healing process.

The multi-faceted immune modulatory role of S100A4 in cancer and chronic inflammatory disease

S100A4 is a Ca2+-binding protein involved in multiple chronic inflammatory and neoplastic conditions. This review focuses on recent advances in the understanding of S100A4 function in immune cells, comparing and contrasting S100A4 regulation of immune responses in cancer and chronic inflammatory diseases. We provide evidence that S100A4 regulation of immune cell function has a profound role in promoting the pathogenesis of cancer and pro-inflammatory conditions. Finally, we discuss relevant future directions to target S100A4 therapeutically in different disease states.

Interferon regulatory factor 5 attenuates kidney fibrosis through transcriptional suppression of Tgfbr1

Tubulointerstitial fibrosis is a common pathway of the progressive development of chronic kidney diseases (CKD) with different etiologies. The transcription factor interferon regulatory factor 5 (IRF5) can induce anti-type I interferons and proinflammatory cytokine genes and has been implicated as a therapeutic target for various inflammatory and autoimmune diseases. Currently, no experimental evidence has confirmed the role of IRF5 in CKD. Our results showed that IRF5 was aberrantly upregulated in fibrotic kidneys of CKD patients and was colocalized with tubular epithelial cells, peritubular endothelial cells and kidney interstitial fibroblasts. Up-regulation of IRF5 was also seen in unilateral ureteral obstruction (UUO), unilateral ischemia reperfusion and repeated low-dose cisplatin induced mice models, as well as TGF-β1-stimulated tubular epithelial cells and interstitial fibroblasts. Knockdown of Irf5 aggravated the degree of renal fibrosis in UUO mice. Consistently, overexpression of Irf5 attenuated TGF-β1-induced partial epithelial-to-mesenchymal transition and endothelial mesenchymal transition, as well as renal interstitial fibroblast activation and proliferation. Mechanistically, IRF5 can bind to the promoter region of Tgfbr1 and inhibit its transcription, thus inhibiting pro-fibrosis TGF-β1/Smad3 signal transduction. In summary, this research revealed an anti-fibrotic effect of exogenous IRF5 in tubular epithelial cells, endothelial cells and intestinal fibroblasts via transcriptionally repressing Tgfbr1. Activating IRF5 could therefore be a novel therapeutic strategy in the prevention of renal fibrosis.

Effect of Anti-S100A4 Monoclonal Antibody Treatment on Experimental Skin Fibrosis and Systemic Sclerosis-Specific Transcriptional Signatures in Human Skin

OBJECTIVE

S100A4 is a DAMP protein. S100A4 is overexpressed in patients with systemic sclerosis (SSc), and levels correlate with organ involvement and disease activity. S100A4-/- mice are protected from fibrosis. The aim of this study was to assess the antifibrotic effects of anti-S100A4 monoclonal antibody (mAb) in murine models of SSc and in precision cut skin slices of patients with SSc.

METHODS

The effects of anti-S100A4 mAbs were evaluated in a bleomycin-induced skin fibrosis model and in Tsk-1 mice with a therapeutic dosing regimen. In addition, the effects of anti-S100A4 mAbs on precision cut SSc skin slices were analyzed by RNA sequencing.

RESULTS

Inhibition of S100A4 was effective in the treatment of pre-established bleomycin-induced skin fibrosis and in regression of pre-established fibrosis with reduced dermal thickening, myofibroblast counts, and collagen accumulation. Transcriptional profiling demonstrated targeting of multiple profibrotic and proinflammatory processes relevant to the pathogenesis of SSc on targeted S100A4 inhibition in a bleomycin-induced skin fibrosis model. Moreover, targeted S100A4 inhibition also modulated inflammation- and fibrosis-relevant gene sets in precision cut SSc skin slices in an ex vivo trial approach. Selected downstream targets of S100A4, such as AMP-activated protein kinase, calsequestrin-1, and phosphorylated STAT3, were validated on the protein level, and STAT3 inhibition was shown to prevent the profibrotic effects of S100A4 on fibroblasts in human skin.

CONCLUSION

Inhibition of S100A4 confers dual targeting of inflammatory and fibrotic pathways in complementary mouse models of fibrosis and in SSc skin. These effects support the further development of anti-S100A4 mAbs as disease-modifying targeted therapies for SSc.

METTL14 downregulation drives S100A4+ monocyte-derived macrophages via MyD88/NF-κB pathway to promote MAFLD progression

Without intervention, a considerable proportion of patients with metabolism-associated fatty liver disease (MAFLD) will progress from simple steatosis to metabolism-associated steatohepatitis (MASH), liver fibrosis, and even hepatocellular carcinoma. However, the molecular mechanisms that control progressive MAFLD have yet to be fully determined. Here, we unraveled that the expression of the N6-methyladenosine (m6A) methyltransferase METTL14 is remarkably downregulated in the livers of both patients and several murine models of MAFLD, whereas hepatocyte-specific depletion of this methyltransferase aggravated lipid accumulation, liver injury, and fibrosis. Conversely, hepatic Mettl14 overexpression alleviated the above pathophysiological changes in mice fed on a high-fat diet (HFD). Notably, in vivo and in vitro mechanistic studies indicated that METTL14 downregulation decreased the level of GLS2 by affecting the translation efficiency mediated by YTHDF1 in an m6A-depedent manner, which might help to form an oxidative stress microenvironment and accordingly recruit Cx3cr1+Ccr2+ monocyte-derived macrophages (Mo-macs). In detail, Cx3cr1+Ccr2+ Mo-macs can be categorized into M1-like macrophages and S100A4-positive macrophages and then further activate hepatic stellate cells (HSCs) to promote liver fibrosis. Further experiments revealed that CX3CR1 can activate the transcription of S100A4 via CX3CR1/MyD88/NF-κB signaling pathway in Cx3cr1+Ccr2+ Mo-macs. Restoration of METTL14 or GLS2, or interfering with this signal transduction pathway such as inhibiting MyD88 could ameliorate liver injuries and fibrosis. Taken together, these findings indicate potential therapies for the treatment of MAFLD progression.

S100A4 modulates cell proliferation, apoptosis and fibrosis in the hyperplastic prostate

Benign prostatic hyperplasia (BPH) is one of the most common diseases in elderly men worldwide that may result in lower urinary tract symptoms (LUTS). At present, the specific pathophysiological mechanism for BPH/LUTS LUTS remains unclear. S100 calcium binding protein A4 (S100A4), a member of the calcium binding protein family, regulates a variety of biological processes including cell proliferation, apoptosis and fibrosis. The aim of the current study was to explore and clarify the possible role of S100A4 in BPH/LUTS. The human prostate stromal cell line (WPMY-1), rat prostate epithelial cells, human prostate tissues and two BPH rat models were employed in this study. The expression and localization of S100A4 were detected by quantitative real time PCR (qRT-PCR), immunofluorescence microscopy, Western blotting and immunohistochemistry analysis. Also, S100A4 knockdown or overexpression cell models were constructed and a BPH rat model was induced with testosterone propionate (T) or phenylephrine (PE). The BPH animals were treated with Niclosamide, a S100A4 transcription inhibitor. Results demonstrated that S100A4 was mainly localized in human prostatic stroma and rat prostatic epithelium, and showed a higher expression in BPH. Knockdown of S100A4 induced cell apoptosis, cell proliferation arrest and a reduction of tissue fibrosis markers. Overexpression of S100A4 reversed the aforementioned changes. We also demonstrated that S100A4 regulated proliferation and apoptosis mainly through the ERK pathway and modulated fibrosis via Wnt/β-catenin signaling. In conclusion, our novel data demonstrate that S100A4 could play a crucial role in BPH development and may be explored as a new therapeutic target of BPH.

Schistosoma mansoni infection induces hepatic metallothionein and S100 protein expression alongside metabolic dysfunction in hamsters

Schistosomiasis, a widespread neglected tropical disease, presents a complex and multifaceted clinical-pathological profile. Using hamsters as final hosts, we dissected molecular events following Schistosoma mansoni infection in the liver-the organ most severely affected in schistosomiasis patients. Employing tandem mass tag-based proteomics, we studied alterations in the liver proteins in response to various infection modes and genders. We examined livers from female and male hamsters that were: noninfected (control), infected with either unisexual S. mansoni cercariae (single-sex) or both sexes (bisex). The infection induced up-regulation of proteins associated with immune response, cytoskeletal reorganization, and apoptotic signaling. Notably, S. mansoni egg deposition led to the down-regulation of liver factors linked to energy supply and metabolic processes. Gender-specific responses were observed, with male hamsters showing higher susceptibility, supported by more differentially expressed proteins than found in females. Of note, metallothionein-2 and S100a6 proteins exhibited substantial up-regulation in livers of both genders, suggesting their pivotal roles in the liver's injury response. Immunohistochemistry and real-time-qPCR confirmed strong up-regulation of metallothionein-2 expression in the cytoplasm and nucleus upon the infection. Similar findings were seen for S100a6, which localized around granulomas and portal tracts. We also observed perturbations in metabolic pathways, including down-regulation of enzymes involved in xenobiotic biotransformation, cellular energy metabolism, and lipid modulation. Furthermore, lipidomic analyses through liquid chromatography-tandem mass spectrometry and matrix-assisted laser desorption/ionization mass spectrometry imaging identified extensive alterations, notably in cardiolipin and triacylglycerols, suggesting specific roles of lipids during pathogenesis. These findings provide unprecedented insights into the hepatic response to S. mansoni infection, shedding light on the complexity of liver pathology in this disease.

IRF3 activates RB to authorize cGAS-STING-induced senescence and mitigate liver fibrosis

Cytosolic double-stranded DNA surveillance by cyclic GMP-AMP synthase (cGAS)-Stimulator of Interferon Genes (STING) signaling triggers cellular senescence, autophagy, biased mRNA translation, and interferon-mediated immune responses. However, detailed mechanisms and physiological relevance of STING-induced senescence are not fully understood. Here, we unexpectedly found that interferon regulatory factor 3 (IRF3), activated during innate DNA sensing, forms substantial endogenous complexes in the nucleus with retinoblastoma (RB), a key cell cycle regulator. The IRF3-RB interaction attenuates cyclin-dependent kinase 4/6 (CDK4/6)-mediated RB hyperphosphorylation that mobilizes RB to deactivate E2 family (E2F) transcription factors, thereby driving cells into senescence. STING-IRF3-RB signaling plays a notable role in hepatic stellate cells (HSCs) within various murine models, pushing activated HSCs toward senescence. Accordingly, IRF3 global knockout or conditional deletion in HSCs aggravated liver fibrosis, a process mitigated by the CDK4/6 inhibitor. These findings underscore a straightforward yet vital mechanism of cGAS-STING signaling in inducing cellular senescence and unveil its unexpected biology in limiting liver fibrosis.

S100A4 a classical DAMP as a therapeutic target in fibrosis

Fibrosis regardless of aetiology is characterised by persistently activated myofibroblasts that are contractile and secrete excessive amounts of extracellular matrix molecules that leads to loss of organ function. Damage-Associated Molecular Patterns (DAMPs) are endogenous host-derived molecules that are released from cells dying or under stress that can be triggered by a variety of insults, either chemical or physical, leading to an inflammatory response. Among these DAMPs is S100A4, part of the S100 family of calcium binding proteins that participate in a variety of cellular processes. S100A4 was first described in context of cancer as a pro-metastatic factor. It is now appreciated that aside from its role in cancer promotion, S100A4 is intimately involved in tissue fibrosis. The extracellular form of S100A4 exerts its effects through multiple receptors including Toll-Like Receptor 4 and RAGE to evoke signalling cascades involving downstream mediators facilitating extracellular matrix deposition and myofibroblast generation and can play a role in persistent activation of myofibroblasts. S100A4 may be best understood as an amplifier of inflammatory and fibrotic processes. S100A4 appears critical in systemic sclerosis pathogenesis and blocking the extracellular form of S100A4 in vivo in various animal models of disease mitigates fibrosis and may even reverse established disease. This review appraises S100A4's position as a DAMP and its role in fibrotic conditions and highlight therapeutically targeting this protein to halt fibrosis, suggesting that it is a tractable target.

Identification and Analysis of DNA Methylation Inflammation-Related Key Genes in Intracerebral Hemorrhage

Inflammation and DNA methylation have been reported to play key roles in intracerebral hemorrhage (ICH). This study aimed to investigate new diagnostic biomarkers associated with inflammation and DNA methylation using a comprehensive bioinformatics approaches. GSE179759 and GSE125512 were collected from the Gene Expression Omnibus database, and 3222 inflammation-related genes (IFRGs) were downloaded from the Molecular Signatures Database. Key differentially expressed methylation-regulated and inflammation-related genes (DE-MIRGs) were identified by overlapping methylation-regulated differentially expressed genes (MeDEGs) between patients with ICH and control samples, module genes from weighted correlation network analysis, and IFRGs. Functional annotation of DE-MIRGs was performed using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG). A protein-protein interaction (PPI) network was constructed to clarify the interrelationships between different DE-MIRGs. The key genes were categorized by least absolute shrinkage selection operator (LASSO) and support vector machine-recursive feature elimination (SVM-RFE), and gene set enrichment analysis (GSEA). A total of 22 DE-MIRGs were acquired from 451 MeDEGs, 3222 IFRGs, and 302 module genes, and were mainly enriched in the GO terms of wound healing, blood coagulation, and hemostasis; and the KEGG pathways of PI3K/Akt signaling, focal adhesion, and regulation of actin cytoskeleton. A PPI network with 22 nodes and 87 edges was constructed based on the 22 DE-MIRGs, 11 of which were selected for key gene selection. Two 2 key genes (SELP and S100A4) were identified using LASSO and SVM-RFE. Finally, SELP was mainly enriched in cell morphogenesis involved in differentiation, cytoplasmic translation, and actin binding of GO terms, and the KEGG pathway including endocytosis, focal adhesion, and platelet activation. S100A4 was mainly enriched in GO terms including mitochondrial inner membrane; mitochondrial respirasome and lysosomal membrane; and the KEGG pathway of oxidative phosphorylation, regulation of actin cytoskeleton, and chemical carcinogenesis-reactive oxygen species. Twenty-two DE-MIRGs-associated inflammation and DNA methylation were identified between patients with ICH and normal controls, and two key genes (SELP and S100A4) were identified and regarded as biomarkers for ICH, which could provide the research foundation for further investigation of the pathological mechanism of ICH.

MyD88 in myofibroblasts enhances nonalcoholic fatty liver disease-related hepatocarcinogenesis via promoting macrophage M2 polarization

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is a major cause of chronic liver diseases and has emerged as the leading factor in the pathogenesis of hepatocellular carcinoma (HCC). MyD88 contributes to the development of HCC. However, the underlying mechanism by which MyD88 in myofibroblasts regulates NAFLD-associated liver cancer development remains unknown.

RESULTS

Myofibroblast MyD88-deficient (SMAMyD88-/-) mice were protected from diet-induced obesity and developed fewer and smaller liver tumors. MyD88 deficiency in myofibroblasts attenuated macrophage M2 polarization and fat accumulation in HCC tissues. Mechanistically, MyD88 signaling in myofibroblasts enhanced CCL9 secretion, thereby promoting macrophage M2 polarization. This process may depend on the CCR1 receptor and STAT6/ PPARβ pathway. Furthermore, liver tumor growth was attenuated in mice treated with a CCR1 inhibitor. CCLl5 (homologous protein CCL9 in humans) expression was increased in myofibroblasts of HCC and was associated with shorter survival of patients with HCC. Thus, our results indicate that MyD88 in myofibroblasts promotes NAFLD-related HCC progression and may be a promising therapeutic target for HCC treatment.

CONCLUSION

This study demonstrates that MyD88 in myofibroblasts can promote nonalcoholic fatty liver disease-related hepatocarcinogenesis by enhancing macrophage M2 polarization, which might provide a potential molecular therapeutic target for HCC.

A novel mechanoeffector role of fibroblast S100A4 in myofibroblast transdifferentiation and fibrosis

Fibroblast to myofibroblast transdifferentiation mediates numerous fibrotic disorders, such as idiopathic pulmonary fibrosis (IPF). We have previously demonstrated that non-muscle myosin II (NMII) is activated in response to fibrotic lung extracellular matrix, thereby mediating myofibroblast transdifferentiation. NMII-A is known to interact with the calcium-binding protein S100A4, but the mechanism by which S100A4 regulates fibrotic disorders is unclear. In this study, we show that fibroblast S100A4 is a calcium-dependent, mechanoeffector protein that is uniquely sensitive to pathophysiologic-range lung stiffness (8-25 kPa) and thereby mediates myofibroblast transdifferentiation. Re-expression of endogenous fibroblast S100A4 rescues the myofibroblastic phenotype in S100A4 KO fibroblasts. Analysis of NMII-A/actin dynamics reveals that S100A4 mediates the unraveling and redistribution of peripheral actomyosin to a central location, resulting in a contractile myofibroblast. Furthermore, S100A4 loss protects against murine in vivo pulmonary fibrosis, and S100A4 expression is dysregulated in IPF. Our data reveal a novel mechanosensor/effector role for endogenous fibroblast S100A4 in inducing cytoskeletal redistribution in fibrotic disorders such as IPF.

CARD9 deficiency aggravated nonalcoholic steatohepatitis in mice through increasing inflammatory response

Nonalcoholic steatohepatitis (NASH), a subtype of nonalcoholic fatty liver disease (NAFLD), is the leading cause of liver-related morbidity worldwide. Caspase recruitment domain family member 9 (CARD9), a myeloid cell-specific signaling protein, belongs to the CARD protein family. However, its role in NASH is unknown. Therefore, this study aimed to investigate the role of CARD9 in the development of NASH. NASH models were established using CARD9-knockout and wild-type mice. They were either fed a methionine/choline deficient (MCD) diet for 6 weeks or a high-fat high-cholesterol (HFHC) diet for 16 weeks. Liver fibrosis model was also developed using CCl4. CARD9 deficiency accelerated steatohepatitis development in MCD or HFHC diet-fed mice, accompanied by an upregulation of fibrosis, adipogenesis, and proinflammatory genes. CARD9 deficiency was found to exacerbate CCl4-induced liver fibrosis. In vitro studies demonstrated that CARD9 deficiency induced the expression of S100a8/a9 through Toll-like receptor in Kupffer cells treated with palmitate. This led to an increased expression of proinflammatory, fibrosis, and lipid metabolism-related genes in NASH progression. These results highlight the role of CARD9 in the development of NASH and provide new insights into the therapeutic strategies for NASH.

Elafibranor upregulates the EMT-inducer S100A4 via PPARβ/δ

Elafibranor is a dual peroxisome proliferator-activated receptor (PPAR)α and β/δ agonist that has reached a phase III clinical trial for the treatment of metabolic dysfunction-associated steatotic liver disease (MASLD). Here, we examined the effects of elafibranor in mice fed a choline-deficient high-fat diet (CD-HFD), a model of metabolic dysfunction-associated steatohepatitis (MASH) that presents obesity and insulin resistance. Our findings revealed that elafibranor treatment ameliorated steatosis, inflammation, and fibrogenesis in the livers of CD-HFD-fed mice. Unexpectedly, elafibranor also increased the levels of the epithelial-mesenchymal transition (EMT)-promoting protein S100A4 via PPARβ/δ activation. The increase in S100A4 protein levels caused by elafibranor was accompanied by changes in the levels of markers associated with the EMT program. The S100A4 induction caused by elafibranor was confirmed in the BRL-3A rat liver cells and a mouse primary hepatocyte culture. Furthermore, elafibranor reduced the levels of ASB2, a protein that promotes S100A4 degradation, while ASB2 overexpression prevented the stimulating effect of elafibranor on S100A4. Collectively, these findings reveal an unexpected hepatic effect of elafibranor on increasing S100A4 and promoting the EMT program.

Anti-S100A4 antibody administration alleviates bronchial epithelial-mesenchymal transition in asthmatic mice

We elucidated the effect of S100A4 on airway remodeling by regulating airway inflammation and epithelial-mesenchymal transition (EMT) in mouse models of asthma. Asthmatic mouse models were established by sensitization and challenged with ovalbumin (OVA). Anti-S100A4 antibody or control IgG antibody was administered daily before the OVA challenge. After the last challenge, airway inflammation and airway hyperresponsiveness were measured; lung tissues and bronchoalveolar lavage fluid (BALF) were harvested. Lung tissue sections were stained and evaluated for pathological changes. Levels of inflammatory cytokines were measured using ELISA. Levels of S100A4 and EMT markers were determined via western blotting analysis. Human bronchial epithelial cells were stimulated with 100 mg/mL house dust mites (HDMs) to evaluate the effect of S100A4 downregulation on EMT in vitro. S100A4 was increased in lung tissues and BALF from asthmatic mice. The asthmatic mice presented airway hyperresponsiveness, airway inflammation, and airway remodeling. After anti-S100A4 antibody administration, pathophysiological signs, including airway hyperresponsiveness and increased infiltration of inflammatory cells, were attenuated. Additionally, anti-S100A4 administration downregulated vimentin and α-SMA expression and upregulated E-cadherin expression in OVA-challenged mice. S100A4 downregulation also inhibited EMT process in HDM-stimulated 16HBE cells. Anti-S100A4 antibody administration alters airway remodeling by preventing EMT in mouse models of asthma.

TP53RK Drives the Progression of Chronic Kidney Disease by Phosphorylating Birc5

Renal fibrosis is a common characteristic of various chronic kidney diseases (CKDs) driving the loss of renal function. During this pathological process, persistent injury to renal tubular epithelial cells and activation of fibroblasts chiefly determine the extent of renal fibrosis. In this study, the role of tumor protein 53 regulating kinase (TP53RK) in the pathogenesis of renal fibrosis and its underlying mechanisms is investigated. TP53RK is upregulated in fibrotic human and animal kidneys with a positive correlation to kidney dysfunction and fibrotic markers. Interestingly, specific deletion of TP53RK either in renal tubule or in fibroblasts in mice can mitigate renal fibrosis in CKD models. Mechanistic investigations reveal that TP53RK phosphorylates baculoviral IAP repeat containing 5 (Birc5) and facilitates its nuclear translocation; enhanced Birc5 displays a profibrotic effect possibly via activating PI3K/Akt and MAPK pathways. Moreover, pharmacologically inhibiting TP53RK and Birc5 using fusidic acid (an FDA-approved antibiotic) and YM-155(currently in clinical phase 2 trials) respectively both ameliorate kidney fibrosis. These findings demonstrate that activated TP53RK/Birc5 signaling in renal tubular cells and fibroblasts alters cellular phenotypes and drives CKD progression. A genetic or pharmacological blockade of this axis serves as a potential strategy for treating CKDs.

The S100 calcium-binding protein A6 plays a crucial role in hepatic steatosis by mediating lipophagy

BACKGROUND

S100 calcium-binding protein A6 (S100A6) is a calcium-binding protein that is involved in a variety of cellular processes, such as proliferation, apoptosis, and the cellular response to various stress stimuli. However, its role in NAFLD and associated metabolic diseases remains uncertain.

METHODS AND RESULTS

In this study, we revealed a new function and mechanism of S100A6 in NAFLD. S100A6 expression was upregulated in human and mouse livers with hepatic steatosis, and the depletion of hepatic S100A6 remarkably inhibited lipid accumulation, insulin resistance, inflammation, and obesity in a high-fat, high-cholesterol (HFHC) diet-induced murine hepatic steatosis model. In vitro mechanistic investigations showed that the depletion of S100A6 in hepatocytes restored lipophagy, suggesting S100A6 inhibition could alleviate HFHC-induced NAFLD. Moreover, S100A6 liver-specific ablation mediated by AAV9 alleviated NAFLD in obese mice.

CONCLUSIONS

Our study demonstrates that S100A6 functions as a positive regulator of NAFLD, targeting the S100A6-lipophagy axis may be a promising treatment option for NAFLD and associated metabolic diseases.

Intestinal B cells license metabolic T-cell activation in NASH microbiota/antigen-independently and contribute to fibrosis by IgA-FcR signalling

BACKGROUND & AIMS

The progression of non-alcoholic steatohepatitis (NASH) to fibrosis and hepatocellular carcinoma (HCC) is aggravated by auto-aggressive T cells. The gut-liver axis contributes to NASH, but the mechanisms involved and the consequences for NASH-induced fibrosis and liver cancer remain unknown. We investigated the role of gastrointestinal B cells in the development of NASH, fibrosis and NASH-induced HCC.

METHODS

C57BL/6J wild-type (WT), B cell-deficient and different immunoglobulin-deficient or transgenic mice were fed distinct NASH-inducing diets or standard chow for 6 or 12 months, whereafter NASH, fibrosis, and NASH-induced HCC were assessed and analysed. Specific pathogen-free/germ-free WT and μMT mice (containing B cells only in the gastrointestinal tract) were fed a choline-deficient high-fat diet, and treated with an anti-CD20 antibody, whereafter NASH and fibrosis were assessed. Tissue biopsy samples from patients with simple steatosis, NASH and cirrhosis were analysed to correlate the secretion of immunoglobulins to clinicopathological features. Flow cytometry, immunohistochemistry and single-cell RNA-sequencing analysis were performed in liver and gastrointestinal tissue to characterise immune cells in mice and humans.

RESULTS

Activated intestinal B cells were increased in mouse and human NASH samples and licensed metabolic T-cell activation to induce NASH independently of antigen specificity and gut microbiota. Genetic or therapeutic depletion of systemic or gastrointestinal B cells prevented or reverted NASH and liver fibrosis. IgA secretion was necessary for fibrosis induction by activating CD11b+CCR2+F4/80+CD11c-FCGR1+ hepatic myeloid cells through an IgA-FcR signalling axis. Similarly, patients with NASH had increased numbers of activated intestinal B cells; additionally, we observed a positive correlation between IgA levels and activated FcRg+ hepatic myeloid cells, as well the extent of liver fibrosis.

CONCLUSIONS

Intestinal B cells and the IgA-FcR signalling axis represent potential therapeutic targets for the treatment of NASH.

IMPACT AND IMPLICATIONS

There is currently no effective treatment for non-alcoholic steatohepatitis (NASH), which is associated with a substantial healthcare burden and is a growing risk factor for hepatocellular carcinoma (HCC). We have previously shown that NASH is an auto-aggressive condition aggravated, amongst others, by T cells. Therefore, we hypothesized that B cells might have a role in disease induction and progression. Our present work highlights that B cells have a dual role in NASH pathogenesis, being implicated in the activation of auto-aggressive T cells and the development of fibrosis via activation of monocyte-derived macrophages by secreted immunoglobulins (e.g., IgA). Furthermore, we show that the absence of B cells prevented HCC development. B cell-intrinsic signalling pathways, secreted immunoglobulins, and interactions of B cells with other immune cells are potential targets for combinatorial NASH therapies against inflammation and fibrosis.

The SLIT/ROBO Pathway in Liver Fibrosis and Cancer

Liver fibrosis is a common outcome of most chronic liver insults/injuries that can develop into an irreversible process of cirrhosis and, eventually, liver cancer. In recent years, there has been significant progress in basic and clinical research on liver cancer, leading to the identification of various signaling pathways involved in tumorigenesis and disease progression. Slit glycoprotein (SLIT)1, SLIT2, and SLIT3 are secreted members of a protein family that accelerate positional interactions between cells and their environment during development. These proteins signal through Roundabout receptor (ROBO) receptors (ROBO1, ROBO2, ROBO3, and ROBO4) to achieve their cellular effects. The SLIT and ROBO signaling pathway acts as a neural targeting factor regulating axon guidance, neuronal migration, and axonal remnants in the nervous system. Recent findings suggest that various tumor cells differ in SLIT/ROBO signaling levels and show varying degrees of expression patterns during tumor angiogenesis, cell invasion, metastasis, and infiltration. Emerging roles of the SLIT and ROBO axon-guidance molecules have been discovered in liver fibrosis and cancer development. Herein, we examined the expression patterns of SLIT and ROBO proteins in normal adult livers and two types of liver cancers: hepatocellular carcinoma and cholangiocarcinoma. This review also summarizes the potential therapeutics of this pathway for anti-fibrosis and anti-cancer drug development.

New progress with calcium-binding protein S100A16 in digestive system disease

INTRODUCTION

This review summarizes and analyzes the abnormal expression and mechanism of S100A16 in digestive system diseases, which is expected to provide new ideas and methods for adjuvant treatment and prognosis evaluation of digestive system diseases.

AREAS COVERED

Based on original publications found in database systems (PubMed, Cochrane), we introduce the mechanism and research progress of S100A16 in digestive system tumors, inflammatory bowel disease and fatty liver.

EXPERT OPINION

S100A16 is closely related to the proliferation, migration, and invasion of digestive system tumor cells. Further, it plays an important role in inflammatory bowel disease and fatty liver.

Metformin attenuates fibroblast activation during pulmonary fibrosis by targeting S100A4 via AMPK-STAT3 axis

Fibroblasts activation is a crucial process for development of fibrosis during idiopathic pulmonary fibrosis pathogenesis, and transforming growth factor (TGF)-β1 plays a key regulatory role in fibroblast activation. It has been reported that metformin (MET) alleviated bleomycin (BLM)-induced pulmonary fibrosis (PF) by regulating TGF-β1-induced fibroblasts activation, but the underlying mechanisms still deserve further investigations. In this study, MET blocked α-smooth muscle actin (α-SMA) accumulation in vivo accompanied with S100A4 expression and STAT3 phosphorylation inhibition, resulting in attenuating the progression of lung fibrosis after BLM administration. We determined that S100A4 plays critical roles in fibroblasts activation in vitro, evidenced by siRNA knockdown of S100A4 expression downregulated TGF-β1 induced α-SMA production in Human fetal lung fibroblast (HFL1) cells. Importantly, we found for the first time that the expression of S100A4 in fibroblasts was regulated by STAT3. Stattic, an effective small molecule inhibitor of STAT3 phosphorylation, reduced S100A4 level in TGF-β1- treated HFL1 cells accompanied with less α-SMA production. We further found that MET, which inhibits STAT3 phosphorylation by AMPK activation, also inhibits fibroblasts activation by targeting S100A4 in vitro. Together all these results, we conclude that S100A4 contributes to TGF-β1- induced pro-fibrogenic function in fibroblasts activation, and MET was able to protect against TGF-β1-induced fibroblasts activation and BLM-induced PF by down-regulating S100A4 expression through AMPK-STAT3 axis. These results provide a useful clue for a clinical strategy to prevent PF.

S100A4-dependent glycolysis promotes lymphatic vessel sprouting in tumor

Tumor-induced lymphangiogenesis promotes the formation of new lymphatic vessels, contributing to lymph nodes (LNs) metastasis of tumor cells in both mice and humans. Vessel sprouting appears to be a critical step in this process. However, how lymphatic vessels sprout during tumor lymphangiogenesis is not well-established. Here, we report that S100A4 expressed in lymphatic endothelial cells (LECs) promotes lymphatic vessel sprouting in a growing tumor by regulating glycolysis. In mice, the loss of S100A4 in a whole body (S100A4^-/-), or specifically in LECs (S100A4^ΔLYVE1) leads to impaired tumor lymphangiogenesis and disrupted metastasis of tumor cells to sentinel LNs. Using a 3D spheroid sprouting assay, we found that S100A4 in LECs was required for the lymphatic vessel sprouting. Further investigations revealed that S100A4 was essential for the position and motility of tip cells, where it activated AMPK-dependent glycolysis during lymphatic sprouting. In addition, the expression of S100A4 in LECs was upregulated under hypoxic conditions. These results suggest that S100A4 is a novel regulator of tumor-induced lymphangiogenesis. Targeting S100A4 in LECs may be a potential therapeutic strategy for lymphatic tumor metastasis.

Asiaticoside conveys an antifibrotic effect by inhibiting activation of hepatic stellate cells via the Jagged-1/Notch-1 pathway

The aim of this study was to investigate the underlying protective mechanisms of asiaticoside (AS) against liver fibrosis (LF) both in vivo and in vitro. A rat model with carbon tetrachloride (CCl₄)-induced liver fibrosis is employed to verify the effect and mechanism of AS on the process of liver fibrosis in vivo experiment. Hematoxylin/eosin and sirius red staining was conducted to assess the severity of liver injury and fibrosis. Further, the serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), albumin (ALB), glutamyl transferase (GGT), and total bilirubin (TBil) were measured. In addition, LX2 cells were cultured for vitro experiment to investigate the influence of AS on hepatic stellate cells (HSCs). Overproduction of α-smooth muscle actin and type I collagen is characteristic of LF and HSCs, as determined by immunohistochemical and Western blot analyses. The expression levels of molecules associated with the Notch signaling pathway (i.e., Notch-1, Jagged-1, and Delta-like-4) were assessed by Western blot analysis. The results revealed that AS attenuated LF, as defined by reduced deposition of collagen, expression of α-smooth muscle actin and collagen type 1, and expression of biochemical parameters (alanine aminotransferase, aspartate aminotransferase, and hydroxyproline). Notably, AS suppressed the expression levels of Notch-1, Jagged-1, and Delta-like-4 in activated HSCs and LF. Collectively, these results demonstrate that AS prevented the progression of LF by modulating the Notch signaling pathway, indicating that AS has potential therapeutic effects against LF.

In Situ Regulation and Mechanisms of 3D Matrix Stiffness on the Activation and Reversion of Hepatic Stellate Cells

Activated hepatic stellate cells (HSCs) is a key event in the progression of liver fibrosis. HSCs transdifferentiate into myofibroblasts and secrete large amounts of extracellular matrix, resulting in increased liver stiffness. It is difficult for platforms constructed in vitro to simulate the structure, composition, and stiffness of the 3D microenvironment of HSCs in vivo. Here, 3D scaffolds with different stiffness are constructed by decellularizing rat livers at different stages of fibrosis. The effects of matrix stiffness on the proliferation, activation, and reversion of HSCs are studied. The results demonstrate these scaffolds have good cytocompatibility. It is also found that the high stiffness can significantly promote the activation of HSCs, and this process is accompanied by the activation of integrin β1 as well as the nucleation and activation of Yes-associated protein (YAP). Moreover, the low stiffness of the scaffold can promote the reversion of activated HSCs, which is associated with cell apoptosis and accompanied by the inactivation of integrin β1 and YAP. These results suggest that YAP may be a potential therapeutic target for the treatment of liver fibrosis and the theoretical feasibility of inducing activated HSCs reversion to the resting state by regulating matrix stiffness of liver.

Inflammatory type 2 conventional dendritic cells contribute to murine and human cholangitis

BACKGROUND & AIMS

Primary sclerosing cholangitis (PSC) is a progressive cholangiopathy characterised by fibrotic stricturing and inflammation of bile ducts, which seems to be driven by a maladaptive immune response to bile duct injury. The histological finding of dendritic cell expansion in portal fields of patients with PSC prompted us to investigate the role of dendritic cells in orchestrating the immune response to bile duct injury.

METHODS

Dendritic cell numbers and subtypes were determined in different mouse models of cholangitis by flow cytometry based on lineage-imprinted markers. Findings were confirmed by immunofluorescence microscopy of murine livers, and liver samples from patients with PSC were compared to control samples from bariatric surgery patients. Using genetic tools, selected dendritic cell subsets were depleted in murine cholangitis. The dendritic cell response to bile duct injury was determined by single-cell transcriptomics.

RESULTS

Cholangitis mouse models were characterised by selective intrahepatic expansion of type 2 conventional dendritic cells, whereas plasmacytoid and type 1 conventional dendritic cells were not expanded. Expansion of type 2 conventional dendritic cells in human PSC lesions was confirmed by histology. Depletion studies revealed a proinflammatory role of type 2 conventional dendritic cells. Single-cell transcriptomics confirmed inflammatory maturation of the intrahepatic type 2 conventional dendritic cells and identified dendritic cell-derived inflammatory mediators.

CONCLUSIONS

Cholangitis is characterised by intrahepatic expansion and inflammatory maturation of type 2 conventional dendritic cells in response to biliary injury. Therefore, type 2 conventional dendritic cells and their inflammatory mediators might be potential therapeutic targets for the treatment of PSC.

LAY SUMMARY

Primary sclerosing cholangitis (PSC) is an inflammatory liver disease of the bile ducts for which there is no effective treatment. Herein, we show that the inflammatory immune response to bile duct injury is organised by a specific subtype of immune cell called conventional type 2 dendritic cells. Our findings suggest that this cell subtype and the inflammatory molecules it produces are potential therapeutic targets for PSC.

Liver-Derived S100A6 Propels β-Cell Dysfunction in NAFLD

Nonalcoholic fatty liver disease (NAFLD) is an independent predictor of systemic insulin resistance and type 2 diabetes mellitus (T2DM). However, converse correlates between excess liver fat content and β-cell function remain equivocal. Specifically, how the accumulation of liver fat consequent to the enhanced de novo lipogenesis (DNL) leads to pancreatic β-cell failure and eventually to T2DM is elusive. Here, we have identified that low-molecular-weight calcium-binding protein S100A6, or calcyclin, inhibits glucose-stimulated insulin secretion (GSIS) from β cells through activation of the receptor for the advanced glycation end products and diminution of mitochondrial respiration. Serum S100A6 level is elevated both in human patients with NAFLD and in a high-fat diet-induced mouse model of NAFLD. Although serum S100A6 levels are negatively associated with β-cell insulin secretory capacity in human patients, depletion of hepatic S100A6 improves GSIS and glycemia in mice, suggesting that S100A6 contributes to the pathophysiology of diabetes in NAFLD. Moreover, transcriptional induction of hepatic S100A6 is driven by the potent regulator of DNL, carbohydrate response element-binding protein (ChREBP), and ectopic expression of ChREBP in the liver suppresses GSIS in a S100A6-sensitive manner. Together, these data suggest elevated serum levels of S100A6 may serve as a biomarker in identifying patients with NAFLD with a heightened risk of developing β-cell dysfunction. Overall, our data implicate S100A6 as, to our knowledge, a hitherto unknown hepatokine to be activated by ChREBP and that participates in the hepato-pancreatic communication to impair insulin secretion and drive the development of T2DM in NAFLD.

ZIP1+ fibroblasts protect lung cancer against chemotherapy via connexin-43 mediated intercellular Zn2+ transfer

Tumour-stroma cell interactions impact cancer progression and therapy responses. Intercellular communication between fibroblasts and cancer cells using various soluble mediators has often been reported. In this study, we find that a zinc-transporter (ZIP1) positive tumour-associated fibroblast subset is enriched after chemotherapy and directly interconnects lung cancer cells with gap junctions. Using single-cell RNA sequencing, we identify several fibroblast subpopulations, among which Zip1+ fibroblasts are highly enriched in mouse lung tumours after doxorubicin treatment. ZIP1 expression on fibroblasts enhances gap junction formation in cancer cells by upregulating connexin-43. Acting as a Zn2+ reservoir, ZIP1+ fibroblasts absorb and transfer Zn2+ to cancer cells, leading to ABCB1-mediated chemoresistance. Clinically, ZIP1high stromal fibroblasts are also associated with chemoresistance in human lung cancers. Taken together, our results reveal a mechanism by which fibroblasts interact directly with tumour cells via gap junctions and contribute to chemoresistance in lung cancer.

Hepatocyte-Specific Smad4 Deficiency Alleviates Liver Fibrosis via the p38/p65 Pathway

Liver fibrosis is a wound-healing response caused by the abnormal accumulation of extracellular matrix, which is produced by activated hepatic stellate cells (HSCs). Most studies have focused on the activated HSCs themselves in liver fibrosis, and whether hepatocytes can modulate the process of fibrosis is still unclear. Sma mothers against decapentaplegic homologue 4 (Smad4) is a key intracellular transcription mediator of transforming growth factor-β (TGF-β) during the development and progression of liver fibrosis. However, the role of hepatocyte Smad4 in the development of fibrosis is poorly elucidated. Here, to explore the functional role of hepatocyte Smad4 and the molecular mechanism in liver fibrosis, a CCl₄-induced liver fibrosis model was established in mice with hepatocyte-specific Smad4 deletion (Smad4^Δhep). We found that hepatocyte-specific Smad4 deficiency reduced liver inflammation and fibrosis, alleviated epithelial-mesenchymal transition, and inhibited hepatocyte proliferation and migration. Molecularly, Smad4 deletion in hepatocytes suppressed the expression of inhibitor of differentiation 1 (ID1) and the secretion of connective tissue growth factor (CTGF) of hepatocytes, which subsequently activated the p38 and p65 signaling pathways of HSCs in an epidermal growth factor receptor-dependent manner. Taken together, our results clearly demonstrate that the Smad4 expression in hepatocytes plays an important role in promoting liver fibrosis and could therefore be a promising target for future anti-fibrotic therapy.

Protective effect of cilostazol and verapamil against thioacetamide-induced hepatotoxicity in rats may involve Nrf2/GSK-3β/NF-κB signaling pathway

BACKGROUND

Verapamil (VER) and cilostazol (Cilo) are mostly used as cardiovascular drugs; they have beneficial effects on different organs toxicities.

AIM

we investigated whether the Nuclear factor erythroid 2-related factor 2 (Nrf2), Glycogen synthase kinase-3β (GSK-3β), and Nuclear factor-kappa B (NF-κB) pathway involved in the protective role of these drugs against Thioacetamide (TAA) induced hepatotoxicity.

METHOD

male rats were randomized divided into five groups, each group (n = 10): control, TAA, VER+TAA, Cilo+TAA, and VER+Cilo+TAA groups. Hepatotoxicity induced in rats by TAA injection once on the 7th day of the experiment.

RESULTS

TAA-induced hepatotoxicity indicated by a significant elevated in serum markers (Alanine aminotransferases (ALT), Aspartate aminotransferases (AST), and bilirubin), oxidative stress markers (Malondialdehyde (MDA), and Nitric oxide (NO)), and protein levels markers (NF-κB, and S100 calcium-binding protein A4 (S100A4)). Also, TAA decreased Nrf2, and increased GSK-3β genes expression. Histopathological alterations in the liver also appeared as a response to TAA injection. On the other hand VER and/or Cilo significantly prevented TAA-induced hepatotoxicity in rats through significantly decreased in ALT, AST, bilirubin, MDA, NO, NF-κB, and S100A4 protein levels. Also, they increased Nrf2 and decreased GSK-3β genes expression which caused improvement in the histopathological changes of the liver.

CONCLUSION

the addition of verapamil to cilostazol potentiated the hepatoprotective activity, and inhibited the progression of hepatotoxicity caused by TAA through the Nrf2/GSK-3β/NF-κBpathway and their activity on oxidative stress, inflammation, and NF-κB protein expression.

S100a16 deficiency prevents hepatic stellate cells activation and liver fibrosis via inhibiting CXCR4 expression

INTRODUCTION

Liver fibrosis caused by hepatic stellate cells (HSCs) activation is implicated in the pathogenesis of liver diseases. To date, there has been no effective intervention means for this process. S100 proteins are calcium-binding proteins that regulate cell growth and differentiation. This study aimed to investigate whether S100A16 induces HSCs activation and participates in liver fibrosis progression.

METHODS

HSCs were isolated, and the relationship between S100A16 expression and HSCs activation was studied. S100a16 knockdown and transgenic mice were generated and subjected to HSCs activation and liver fibrosis stimulated by different models. Clinical samples were collected for further confirmation. Alterations in gene expression in HSCs were investigated, using transcriptome sequencing to determine the underlying mechanisms.

RESULTS

We observed increased S100A16 levels during HSCs activation. Genetic silencing of S100a16 prevented HSCs activation in vitro. Furthermore, S100a16 silencing exhibited obvious protective effects against HSCs activation and fibrosis progression in mice. In contrast, S100a16 transgenic mice exhibited spontaneous liver fibrosis. S100A16 was also upregulated in the HSCs of patients with fibrotic liver diseases. RNA sequencing revealed that C-X-C motif chemokine receptor 4 (Cxcr4) gene was a crucial regulator of S100A16 induction during HSCs activation. Mechanistically, S100A16 bound to P53 to induce its degradation; this augmented CXCR4 expression to activate ERK 1/2 and AKT signaling, which then promoted HSCs activation and liver fibrosis.

CONCLUSIONS

These data indicate that S100a16 deficiency prevents liver fibrosis by inhibiting Cxcr4 expression. Targeting S100A16 may provide insight into the pathogenesis of liver fibrosis and pave way for the design of novel clinical therapeutic strategies.

S100 Proteins in Fatty Liver Disease and Hepatocellular Carcinoma

Non-alcoholic fatty liver disease (NAFLD) is a highly prevalent and slow progressing hepatic pathology characterized by different stages of increasing severity which can ultimately give rise to the development of hepatocellular carcinoma (HCC). Besides drastic lifestyle changes, few drugs are effective to some extent alleviate NAFLD and HCC remains a poorly curable cancer. Among the deregulated molecular mechanisms promoting NAFLD and HCC, several members of the S100 proteins family appear to play an important role in the development of hepatic steatosis, non-alcoholic steatohepatitis (NASH) and HCC. Specific members of this Ca²⁺-binding protein family are indeed significantly overexpressed in either parenchymal or non-parenchymal liver cells, where they exert pleiotropic pathological functions driving NAFLD/NASH to severe stages and/or cancer development. The aberrant activity of S100 specific isoforms has also been reported to drive malignancy in liver cancers. Herein, we discuss the implication of several key members of this family, e.g., S100A4, S100A6, S100A8, S100A9 and S100A11, in NAFLD and HCC, with a particular focus on their intracellular versus extracellular functions in different hepatic cell types. Their clinical relevance as non-invasive diagnostic/prognostic biomarkers for the different stages of NAFLD and HCC, or their pharmacological targeting for therapeutic purpose, is further debated.

Pharmacological Inhibition of S100A4 Attenuates Fibroblast Activation and Renal Fibrosis

The TGF-β/Smad3 signaling pathway is an important process in the pathogenesis of kidney fibrosis. However, the molecular mechanisms are not completely elucidated. The current study examined the functional role of S100A4 in regulating TGF-β/Smad3 signaling in fibroblast activation and kidney fibrosis development. S100A4 was upregulated in the kidney in a murine model of renal fibrosis induced by folic acid nephropathy. Further, S100A4 was predominant in the tubulointerstitial cells of the kidney. Pharmacological inhibition of S100A4 with niclosamide significantly attenuated fibroblast activation, decreased collagen content, and reduced extracellular matrix protein expression in folic acid nephropathy. Overexpression of S100A4 in cultured renal fibroblasts significantly facilitated TGF-β1-induced activation of fibroblasts by increasing the expression of α-SMA, collagen-1 and fibronectin. In contrast, S100A4 knockdown prevented TGF-β1-induced activation of fibroblast and transcriptional activity of Smad3. Mechanistically, S100A4 interacts with Smad3 to stabilize the Smad3/Smad4 complex and promotes their translocation to the nucleus. In conclusion, S100A4 facilitates TGF-β signaling via interaction with Smad3 and promotes kidney fibrosis development. Manipulating S100A4 may provide a beneficial therapeutic strategy for chronic kidney disease.

Challenges and perspectives of tendon-derived cell therapy for tendinopathy: from bench to bedside

Tendon is composed of dense fibrous connective tissues, connecting muscle at the myotendinous junction (MTJ) to bone at the enthesis and allowing mechanical force to transmit from muscle to bone. Tendon diseases occur at different zones of the tendon, including enthesis, MTJ and midsubstance of the tendon, due to a variety of environmental and genetic factors which consequently result in different frequencies and recovery rates. Self-healing properties of tendons are limited, and cell therapeutic approaches in which injured tendon tissues are renewed by cell replenishment are highly sought after. Homologous use of individual’s tendon-derived cells, predominantly differentiated tenocytes and tendon-derived stem cells, is emerging as a treatment for tendinopathy through achieving minimal cell manipulation for clinical use. This is the first review summarizing the progress of tendon-derived cell therapy in clinical use and its challenges due to the structural complexity of tendons, heterogeneous composition of extracellular cell matrix and cells and unsuitable cell sources. Further to that, novel future perspectives to improve therapeutic effect in tendon-derived cell therapy based on current basic knowledge are discussed.

Effective delivery of osteopontin small interference RNA using exosomes suppresses liver fibrosis via TGF-β1 signaling

Objective and aims: Osteopontin (OPN), an oxidant stress sensitive cytokine, plays a central role in liver fibrosis. While OPN expression can be reduced by small interfering RNA (siRNA), the challenge to deliver siRNA safely and effectively into liver remains unresolved. Exosomes are promising natural nanocarriers for drug delivery that are able to enter cells with different biological barriers efficiently. In this study, we used exosomes as a delivery vehicle to target OPN in liver fibrosis.

Methods: Exosomes selectively home to fibrotic liver according to small animal imaging system. Electroporation technique was used to engineer exosomes to carry siRNA targeting OPN (Exo^siRNA−OPN). Primary hepatic stellate cells (HSCs) were isolated and treated with Exo^siRNA−OPN to assess the effect on activated HSCs (aHSCs). Immunofluorescence for α−SMA, an aHSCs marker, and sirius red staining were performed to assess ECM deposition. Finally, plasma OPN from patients with liver fibrosis was identified by ELISA assay.

Results: Exosome-mediated siRNA delivery systems show high uptake and low toxicity. Besides, Exo^siRNA−OPN suppressed HSCs activation and ECM deposition and more efficiently improved liver function when compared to naked siRNA-OPN. Moreover, Exo^siRNA−OPN was assumed inhibiting TGF-β1 signaling activation, along with other fibrotic-related genes based on a GEO datasheet of liver fibrosis samples for correlation analyzes. Exo^siRNA−OPN inhibited TGF-β1 signaling by decreasing high-mobility group box-1 (HMGB1). Plasma proteins from chronic HBV-induced fibrosis patients were identified that patients with high OPN expression correlates with more advanced fibrosis progression.

Discussion: This study shows that exosome-mediated siRNA-OPN delivery may be an effective option for the treatment of liver fibrosis.

Modulation of hepatic stellate cells by Mutaflor® probiotic in non-alcoholic fatty liver disease management

BACKGROUND

NAFLD and NASH are emerging as primary causes of chronic liver disease, indicating a need for an effective treatment. Mutaflor® probiotic, a microbial treatment of interest, was effective in sustaining remission in ulcerative colitis patients.

OBJECTIVE

To construct a genetic-epigenetic network linked to HSC signaling as a modulator of NAFLD/NASH pathogenesis, then assess the effects of Mutaflor® on this network.

METHODS

First, in silico analysis was used to construct a genetic-epigenetic network linked to HSC signaling. Second, an investigation using rats, including HFHSD induced NASH and Mutaflor® treated animals, was designed. Experimental procedures included biochemical and histopathologic analysis of rat blood and liver samples. At the molecular level, the expression of genetic (FOXA2, TEAD2, and LATS2 mRNAs) and epigenetic (miR-650, RPARP AS-1 LncRNA) network was measured by real-time PCR. PCR results were validated with immunohistochemistry (α-SMA and LATS2). Target effector proteins, IL-6 and TGF-β, were estimated by ELISA.

RESULTS

Mutaflor® administration minimized biochemical and histopathologic alterations caused by NAFLD/NASH. HSC activation and expression of profibrogenic IL-6 and TGF-β effector proteins were reduced via inhibition of hedgehog and hippo pathways. Pathways may have been inhibited through upregulation of RPARP AS-1 LncRNA which in turn downregulated the expression of miR-650, FOXA2 mRNA and TEAD2 mRNA and upregulated LATS2 mRNA expression.

CONCLUSION

Mutaflor® may slow the progression of NAFLD/NASH by modulating a genetic-epigenetic network linked to HSC signaling. The probiotic may be a useful modality for the prevention and treatment of NAFLD/NASH.

Time-resolved proteome and transcriptome of paraquat-induced pulmonary fibrosis

BACKGROUNDS

Pulmonary fibrosis (PF) is a pathological state presenting at the progressive stage of heterogeneous interstitial lung disease (ILD). The current understanding of the molecular mechanisms involved is incomplete. This clinical toxicology study focused on the pulmonary fibrosis induced by paraquat (PQ), a widely-used herbicide. Using proteo-transcriptome analysis, we identified differentially expressed proteins (DEPs) derived from the initial development of fibrosis to the dissolved stage and provided further functional analysis.

METHODS

We established a mouse model of progressive lung fibrosis via intratracheal instillation of paraquat. To acquire a comprehensive and unbiased understanding of the onset of pulmonary fibrosis, we performed time-series proteomics profiling (iTRAQ) and RNA sequencing (RNA-Seq) on lung samples from paraquat-treated mice and saline control. The biological functions and pathways involved were evaluated through Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) Pathway analysis. Correlation tests were conducted on comparable groups 7 days and 28 days post-exposure. Differentially expressed proteins and genes following the same trend on the protein and mRNA levels were selected for validation. The functions of the selected molecules were identified in vitro. The protein level was overexpressed by transfecting gene-containing plasmid or suppressed by transfecting specific siRNA in A549 cells. The levels of endothlial-mesenchymal transition (EMT) markers, including E-cadherin, vimentin, FN1, and α-SMA, were determined via western blot to evaluate the fibrotic process.

RESULTS

We quantified 1358 DEPs on day 7 and 426 DEPs on day 28 post exposure (Fold change >1.2; Q value < 0.05). The top 5 pathways - drug metabolism-cytochrome P450, metabolism of xenobiotics by cytochrome P450, complement and coagulation cascades, chemical carcinogenesis, protein digestion and absorption - were involved on both day 7 and day 28. Several pathways, including tight junction, focal adhesion, platelet activation, and ECM-receptor interaction, were more enriched on day 28 than on day 7. Integrative analysis of the proteome and transcriptome revealed a moderate correlation of quantitative protein abundance ratios with RNA abundance ratios (Spearman R = 0.3950 and 0.2477 on days 7 and 28, respectively), indicating that post-transcriptional regulation plays an important role in lung injury and repair. Western blot identified that the protein expressions of FN1, S100A4, and RBM3 were significantly upregulated while that of CYP1A1, FMO3, and PGDH were significantly downregulated on day 7. All proteins generally recovered to baseline on day 28. qPCR showed the mRNA levels of Fn1, S100a4, Rbm3, Cyp1a1, Fmo3, and Hpgd changed following the same trend as the levels of their respective proteins. Further, in vitro experiments showed that RBM3 was upregulated while PGDH was downregulated in an EMT model established in human lung epithelial A549 cells. RBM3 overexpression and PGDH knockout could both induce EMT in A549 cells. RBM3 knockout or PGDH overexpression had no reverse effect on EMT in A549 cells.

CONCLUSIONS

Our proteo-transcriptomic study determined the proteins responsible for fibrogenesis and uncovers their dynamic regulation from lung injury to repair, providing new insights for the development of biomarkers for diagnosis and treatment of fibrotic diseases.

The tendon microenvironment: Engineered in vitro models to study cellular crosstalk

Tendinopathy is a multi-faceted pathology characterized by alterations in tendon microstructure, cellularity and collagen composition. Challenged by the possibility of regenerating pathological or ruptured tendons, the healing mechanisms of this tissue have been widely researched over the past decades. However, so far, most of the cellular players and processes influencing tendon repair remain unknown, which emphasizes the need for developing relevant in vitro models enabling to study the complex multicellular crosstalk occurring in tendon microenvironments. In this review, we critically discuss the insights on the interaction between tenocytes and the other tendon resident cells that have been devised through different types of existing in vitro models. Building on the generated knowledge, we stress the need for advanced models able to mimic the hierarchical architecture, cellularity and physiological signaling of tendon niche under dynamic culture conditions, along with the recreation of the integrated gradients of its tissue interfaces. In a forward-looking vision of the field, we discuss how the convergence of multiple bioengineering technologies can be leveraged as potential platforms to develop the next generation of relevant in vitro models that can contribute for a deeper fundamental knowledge to develop more effective treatments.

MyD88 in hepatic stellate cells enhances liver fibrosis via promoting macrophage M1 polarization

During liver fibrosis, quiescent HSCs (qHSCs) are activated to become activated HSCs (aHSCs)/myofibroblasts. The signal adapter MyD88, an essential component of TLR signaling, plays an important role in liver fibrosis. However, far less is known about the specific effects of MyD88 signaling in both qHSCs and aHSCs in the progress of liver fibrosis. Here, we used a CCl₄-induced mouse fibrosis model in which MyD88 was selectively depleted in qHSCs (GFAP^MyD88−/− mice) or aHSCs (α-SMA^MyD88−/− mice). MyD88 deficiency in qHSCs or aHSCs attenuated liver fibrosis in mice and inhibited α-SMA-positive cell activation. Inhibition of MyD88 in HSCs decreased α-SMA and collagen I levels, inflammatory cell infiltration, and pro-inflammatory gene expression. Furthermore, MyD88 signaling in HSCs increased the secretion of CXCL10, which promoted macrophage M1 polarization through CXCR3, leading to activation of the JAK/STAT1 pathway. Inhibition of CXCL10 attenuated macrophage M1 polarization and reduced liver fibrosis. Thus, MyD88 signaling in HSCs crucially contributes to liver fibrosis and provides a promising therapeutic target for the prevention and treatment of liver fibrosis.

Macrophage-Secreted S100A4 Supports Breast Cancer Metastasis by Remodeling the Extracellular Matrix in the Premetastatic Niche

Metastasis is the major cause of cancer-related mortalities. A tumor-supportive microenvironment, also known as the premetastatic niche at secondary tumor sites, plays a crucial role in metastasis. Remodeling of the extracellular matrix (ECM) is essential for premetastatic niche formation, especially for circulating tumor cell colonization. However, the underlying molecular mechanism that contributes to this effect remains unclear. Here, we developed a lung metastasis model with 4T1 breast cancer cells and found that the metastasis critically depended on the early recruitment of macrophages to the lung. Disruption of macrophage recruitment reduced fibroblast activation and lung metastasis. Furthermore, we identified the secreted protein S100A4, which is produced by M2 macrophages and participates in fibroblast activation and ECM protein deposition via the ERK signaling pathway. Collectively, these results indicate that recruiting S100A4-expressing inflammatory macrophages plays a vital role in ECM remodeling in the premetastatic niche and may act as a potential therapeutic target for breast cancer lung metastasis.

Celecoxib induces adipogenic differentiation of hemangioma‑derived mesenchymal stem cells through the PPAR‑γ pathway in vitro and in vivo

Infantile hemangioma (IH) is a benign tumor that produces a permanent scar or a mass of fibro-fatty tissue after involution in 40-80% of cases. Celecoxib is an inhibitor of cyclooxygenase-2 (COX-2), and can inhibit angiogenesis and fibrosis. The present study aimed to clarify whether celecoxib is able to induce tumor regression with minimal side effects. For that purpose, the regulation of celecoxib in the involution of IH was investigated in an IH model. Hemangioma-derived mesenchymal stem cells (Hem-MSCs) were isolated from proliferating specimens, and an IH model was established by injecting these cells into nude mice. Celecoxib was administered in vitro and in vivo. Oil Red O staining and reverse transcription-quantitative-PCR were used to detect the adipogenic differentiation of Hem-MSCs. Histologic analysis and immunohistochemical staining of the tumor xenografts were performed to investigate the pathological evolution of the tumor. The results showed that celecoxib inhibited the proliferation and induced the adipogenic differentiation of Hem-MSCs in vitro. In vivo, adipocytes were only present in the celecoxib group at week 4, while a larger number of fibroblasts and collagenous fibers could be observed in the basic fibroblast growth factor group. Therefore, celecoxib may be a potential agent used for IH treatment by inducing adipogenesis and inhibiting fibroblast formation.

Ruxolitinib suppresses liver fibrosis progression and accelerates fibrosis reversal via selectively targeting Janus kinase 1/2

BACKGROUND

JAK1 and JAK2 have been implicated in fibrosis and cancer as a fibroblast-related marker; however, their role in liver fibrosis has not been elucidated. Here, we aim to determine the effect and underlying mechanism of JAK1/2 inhibition on liver fibrosis and hepatic stellate cells (HSCs) and further explore the therapeutic efficacy of Ruxolitinib, a JAK1/2 selective inhibitor, on preventing and reversing liver fibrosis in mice.

METHODS

Immunohistochemistry staining of JAK1 and JAK2 were performed on liver tissue in mice with hepatic fibrosis and human liver tissue microarray of liver cirrhosis and liver cancer. LX-2 cells treated with specific siRNA of JAK1 and JAK2 were used to analysis activation, proliferation and migration of HSCs regulated by JAK1/2. The effects of Ruxolitinib (JAK1/2 inhibitor) on liver fibrosis were studied in LX-2 cells and two progressive and reversible fibrosis animal models (carbon tetrachloride (CCl₄), Thioacetamide (TAA)).

RESULTS

We found that JAK1/2 expression was positively correlated with the progression of HCC in humans and the levels of liver fibrosis in mice. Silencing of JAK1/2 down-regulated their downstream signaling and inhibited proliferation, migration, and activation of HSCs in vitro, while Ruxolitinib had similar effects on HSCs. Importantly, Ruxolitinib significantly attenuated fibrosis progression, improved cell damage, and accelerated fibrosis reversal in the liver of mice treated with CCl₄ or TAA.

CONCLUSIONS

JAK1/2 regulates the function of HSCs and plays an essential role in liver fibrosis and HCC development. Its inhibitor, Ruxolitinib, may be an effective drug for preventing and treating liver fibrosis.

Dysfunction of S100A4+ effector memory CD8+ T cells aggravates asthma

Progressive loss of effector functions, especially IFN-γ secreting capability, in effector memory CD8⁺ T (CD8⁺ T_EM ) cells plays a crucial role in asthma worsening. However, the mechanisms of CD8⁺ T_EM cell dysfunction remain elusive. Here, we report that S100A4 drives CD8⁺ T_EM cell dysfunction, impairing their protective memory response and promoting asthma worsening in an ovalbumin (OVA)-induced asthmatic murine model. We find that CD8⁺ T_EM cells contain two subsets based on S100A4 expression. S100A4⁺ subsets exhibit dysfunctional effector phenotypes with increased proliferative capability, whereas S100A4^- subsets retain effector function but are more inclined to apoptosis, giving rise a dysfunctional CD8⁺ T_EM cell pool. Mechanistically, S100A4 upregulation of mitochondrial metabolism results in a decrease of acetyl-CoA levels, which impair the transcription of effector genes, especially ifn-γ, facilitating cell survival, tolerance and memory potential. Our findings thus reveal general insights into how S100A4 CD8⁺ T_EM cells reprogram into dysfunctional and less protective phenotypes to aggravate asthma. This article is protected by copyright. All rights reserved.

Endothelial c-Myc knockout enhances diet-induced liver inflammation and fibrosis

Endothelial cells play an essential role in inflammation through synthesis and secretion of chemoattractant cytokines and expression of adhesion molecules required for inflammatory cell attachment and infiltration. The mechanisms by which endothelial cells control the pro-inflammatory response depend on the type of inflammatory stimuli, endothelial cell origin, and tissue involved. In the present study, we investigated the role of the transcription factor c-Myc in inflammation using a conditional knockout mouse model in which Myc is specifically deleted in the endothelium. At a systemic level, circulating monocytes, the chemokine CCL7, and the extracellular-matrix protein osteopontin were significantly increased in endothelial c-Myc knockout (EC-Myc KO) mice, whereas the cytokine TNFSF11 was downregulated. Using an experimental model of steatohepatitis, we investigated the involvement of endothelial c-Myc in diet-induced inflammation. EC-Myc KO animals displayed enhanced pro-inflammatory response, characterized by increased expression of pro-inflammatory cytokines and leukocyte infiltration, and worsened liver fibrosis. Transcriptome analysis identified enhanced expression of genes associated with inflammation, fibrosis, and hepatocellular carcinoma in EC-Myc KO mice relative to control (CT) animals after short-exposure to high-fat diet. Analysis of a single-cell RNA-sequencing dataset of human cirrhotic livers indicated downregulation of MYC in endothelial cells relative to healthy controls. In summary, our results suggest a protective role of endothelial c-Myc in diet-induced liver inflammation and fibrosis. Targeting c-Myc and its downstream pathways in the endothelium may constitute a potential strategy for the treatment of inflammatory disease.

MyD88 in myofibroblasts regulates aerobic glycolysis-driven hepatocarcinogenesis via ERK-dependent PKM2 nuclear relocalization and activation

Hepatic stellate cells (HSCs) and cancer-associated fibroblasts (CAFs) play critical roles in liver fibrosis and hepatocellular carcinoma (HCC). MyD88 controls the expression of several key modifier genes in liver tumorigenesis; however, whether and how MyD88 in myofibroblasts contributes to the development of fibrosis-associated liver cancer remain elusive. Here, we used an established hepatocarcinogenesis mouse model involving apparent liver fibrogenesis, in which MyD88 was selectively depleted in myofibroblasts. Myofibroblast MyD88-deficient (Fib-MyD88 KO) mice developed significantly fewer and smaller liver tumor nodules. MyD88 deficiency in myofibroblasts attenuated liver fibrosis and aerobic glycolysis in hepatocellular carcinoma tissues. Mechanistically, MyD88 signaling in myofibroblasts increased the secretion of CCL20, which promoted aerobic glycolysis in cancer cells. This process was dependent on the CCR6 receptor and ERK/PKM2 signaling. Furthermore, liver tumor growth was greatly relieved when the mice were treated with a CCR6 inhibitor. Our data revealed a critical role for MyD88 in myofibroblasts in the promotion of hepatocellular carcinoma by affecting aerobic glycolysis in cancer cells and might provide a potential molecular therapeutic target for HCC. This article is protected by copyright. All rights reserved.

A characterized saponin extract of Panax japonicus suppresses hepatocyte EMT and HSC activation in vitro and CCl4-provoked liver fibrosis in mice: Roles of its modulatory effects on the Akt/GSK3β/Nrf2 cascade

BACKGROUND AND PURPOSE

Liver fibrosis constitutes a pathologic condition resulting in a series of advanced liver diseases. Oleanane-type saponins are distinctive active constituents in the medicinal plant Panax japonicus C. A. Mey (P. japonicus). Herein, we assessed protective effects of a characterized saponin extract of rhizomes of P. japonicus (SEPJ) on hepatocyte EMT and HSC activation in vitro and liver fibrosis in mice. We also investigated molecular mechanisms underlying the hepatoprotective activity of SEPJ.

METHODS

EMT of AML-12 hepatocytes was evaluated by observing morphology of cells and quantifying EMT marker proteins. Activation of LX-2 HSCs was assessed via scratch assay, transwell assay, and EdU-incorporation assay, and by quantifying activation marker proteins. Liver fibrosis in mice was evaluated by HE, SR, and Masson staining, and by measuring related serum indicators. Immunoblotting and RT-PCR were performed to study mechanisms underlying the action of SEPJ.

RESULTS

SEPJ inhibited TGF-β-induced EMT in AML-12 hepatocytes and activation of LX-2 HSCs. SEPJ elevated Akt phosphorylation at Ser473 and GSK3β phosphorylation at Ser9 in these cells, giving rise to a descent of the catalytic activity of GSK3β. These events increased levels of both total and nuclear Nrf2 protein and upregulated expressions of Nrf2-responsive antioxidative genes. In addition, enhanced phosphorylation of Akt and GSK3β acted upstream of SEPJ-mediated activation of Nrf2. Knockdown of Nrf2 or inhibition of Akt diminished the protective activity of SEPJ against TGF-β in both AML-12 and LX-2 cells. Our further in vivo experiments revealed that SEPJ imposed a considerable alleviation on CCl₄-provoked mouse liver fibrosis. Moreover, hepatic Akt/GSK3β/Nrf2 cascade were potentiated by SEPJ. Taken together, our results unveiled that SEPJ exerted protective effects against fibrogenic cytokine TGF-β in vitro and ameliorated liver fibrosis in mice. Mechanistically, SEPJ regulated the Akt/GSK3β/Nrf2 signaling which subsequently enhanced intracellular antioxidative capacity.

CONCLUSIONS

SEPJ inhibits hepatocyte EMT and HSC activation in vitro and alleviates liver fibrosis in mice. Modulation of the Akt/GSK3β/Nrf2 cascade attributes to its hepatoprotective effects. Our findings support a possible application of SEPJ in the control of liver fibrosis.

MyD88 in Macrophages Enhances Liver Fibrosis by Activation of NLRP3 Inflammasome in HSCs

Chronic liver disease mediated by the activation of hepatic stellate cells (HSCs) leads to liver fibrosis. The signal adaptor MyD88 of Toll-like receptor (TLR) signaling is involved during the progression of liver fibrosis. However, the specific role of MyD88 in myeloid cells in liver fibrosis has not been thoroughly investigated. In this study, we used a carbon tetrachloride (CCl₄)-induced mouse fibrosis model in which MyD88 was selectively depleted in myeloid cells. MyD88 deficiency in myeloid cells attenuated liver fibrosis in mice and decreased inflammatory cell infiltration. Furthermore, deficiency of MyD88 in macrophages inhibits the secretion of CXC motif chemokine 2 (CXCL2), which restrains the activation of HSCs characterized by NLR Family Pyrin Domain Containing 3 (NLRP3) inflammasome activation. Moreover, targeting CXCL2 by CXCR2 inhibitors attenuated the activation of HSCs and reduced liver fibrosis. Thus, MyD88 may represent a potential candidate target for the prevention and treatment of liver fibrosis.

Cluster of Differentiation 44 Promotes Liver Fibrosis and Serves as a Biomarker in Congestive Hepatopathy

Congestive hepatopathy (CH) with chronic passive congestion is characterized by the progression of liver fibrosis without prominent inflammation and hepatocellular damage. Currently, the lack of reliable biomarkers for liver fibrosis in CH often precludes the clinical management of patients with CH. To explore fibrosis biomarkers, we performed proteome analysis on serum exosomes isolated from patients with CH after the Fontan procedure. Exosomal cluster of differentiation (CD)44 levels were increased in patients with CH compared to healthy volunteers and was accompanied by increases in serum levels of soluble CD44 and CD44 expression in the liver. To address the roles of CD44 in CH, we established a mouse model of chronic liver congestion by partial inferior vena cava ligation (pIVCL) that mimics CH by fibrosis progression with less inflammation and cellular damage. In the pIVCL mice, enhanced CD44 expression in hepatic stellate cells (HSCs) and deposition of its ligand hyaluronan were observed in the liver. Blood levels of soluble CD44 were correlated with liver fibrosis. The blockade of CD44 with specific antibody inhibited liver fibrosis in pIVCL mice and was accompanied by a reduction in S100 calcium-binding protein A4 expression following activation of HSCs. Conclusion: Chronic liver congestion promotes fibrosis through CD44. This identifies CD44 as a novel biomarker and therapeutic target of liver fibrosis in patients with CH.

S100A4 Is Critical for a Mouse Model of Allergic Asthma by Impacting Mast Cell Activation

Background

The calcium-binding protein S100A4 demonstrates important regulatory roles in many biological processes including tumorigenesis and inflammatory disorders such as allergy. However, the specific mechanism of the contribution of S100A4 to allergic diseases awaits further clarification.

Objective

To address the effect of S100A4 on the regulation of mast cell activation and its impact on allergy.

Methods

Bone marrow-derived cultured mast cells (BMMCs) were derived from wild-type (WT) or S100A4-/- mice for in vitro investigation. WT and S100A4-/- mice were induced to develop a passive cutaneous anaphylaxis (PCA) model, a passive systemic anaphylaxis (PSA) model, and an ovalbumin (OVA)-mediated mouse asthma model.

Results

Following OVA/alum-based sensitization and provocation, S100A4-/- mice demonstrated overall suppressed levels of serum anti-OVA IgE and IgG antibodies and proinflammatory cytokines in serum, bronchoalveolar lavage fluid (BALF), and lung exudates. S100A4-/- mice exhibited less severe asthma signs which included inflammatory cell infiltration in the lung tissue and BALF, and suppressed mast cell recruitment in the lungs. Reduced levels of antigen reencounter-induced splenocyte proliferation in vitro were recorded in splenocytes from OVA-sensitized and challenged mice that lacked S100A4-/-. Furthermore, deficiency in the S100A4 gene could dampen mast cell activation both in vitro and in vivo, evidenced by reduced β-hexosaminidase release and compromised PCA and PSA reaction. We also provided evidence supporting the expression of S100A4 by mast cells.

Conclusion

S100A4 is required for mast cell functional activation, and S100A4 may participate in the regulation of allergic responses at least partly through regulating the activation of mast cells.