Yes-associated protein inhibition ameliorates liver fibrosis and acute and chronic liver failure by decreasing ferroptosis and necroptosis

Piezo1-Mediated Calcium Flux Transfers Mechanosignal to YAP to Stimulate Matrix Production in Keloid

Keloids are fibroproliferative diseases affecting millions worldwide, but curing keloids remains challenging. Mechanical force is a common initiator and driver of keloids, and blocking the pro-adhesive signaling pathways is expected to cure keloids. This study found higher levels of Piezo1 in human keloid fibroblasts (KFbs) compared with normal skin fibroblasts (Fbs). Single-cell transcriptome analysis revealed a correlation of Piezo1 with YAP in KFbs. Knockdown of Piezo1/YAP in KFbs versus Fbs decreased CCN2 and CCN1 expression and fibrosis-related cell behaviors, identifying Piezo1 and YAP as upstream signals of pro-adhesive signaling loop in keloids. Treatment of patient-derived keloid xenograft model with Piezo1 inhibitor GsMTx4 and YAP inhibitor Verteporfin reduced keloid volume and decreased type I/III collagen ratio. Atomic force microscopy further confirmed the biomechanical improvements of keloids in elasticity, viscoelasticity, and roughness ex vivo. In addition, the Ca2+-sensitive fluorescent indicator Fluo-3/AM and double-labelling immunofluorescence stains showed Piezo1 transferred mechanosignal to increase YAP nuclear translocation via calcium flux. Finally, transcriptomics revealed target genes of the Piezo1/YAP signaling pathway, such as TBX3, SESN2, SMAD7, FOSB, JARID2, and HAS2. Consequently, the Piezo1/calcium flux/YAP signaling axis contributes to the mechanically induced pro-adhesive signaling pathway, and thus, Piezo1 and YAP are promising targets for keloid treatment.

USP21 is involved in the development of chronic hepatitis B by modulating the immune microenvironment

Hepatitis B virus (HBV) infection is a global public health challenge that alters the immune microenvironment of the liver and drives disease progression by triggering chronic inflammation that leads to hepatic cell death through multiple programmed cell death (PCD) modalities. Due to the persistence of covalently closed circular DNA in hepatocytes, there is a lack of curative drugs that can completely eradicate HBV. Therefore, revealing how HBV infection leads to changes in the hepatic immune microenvironment, as well as searching for specific molecular targets, is crucial for controlling the onset and progression of chronic hepatitis B (CHB). In this study, we used the single sample gene set enrichment analysis and CIBERSORT algorithms to assess immune cell infiltration in the livers of CHB patients. With three advanced machine learning algorithms, random forest, least absolute shrinkage and selection operator, and selected support vector machine recursive feature elimination, we identified the PCD signature genes associated with CHB from the candidate genes. We further validated that ubiquitin-specific peptidase 21 could differentiate CHB patients with different natural courses by receiver operating characteristic analysis. These findings enhance our understanding of the mechanisms of HBV infection.

Ferroptosis, from the virus point of view: opportunities and challenges

Ferroptosis is a new type of cell death, which is mainly dependent on the formation and accumulation of reactive oxygen species and lipid peroxides mediated by iron. It is distinct from other forms of regulation of cell death in morphology, immunology, biochemistry, and molecular biology. Various cell death mechanisms have been observed in many viral infections, and virus-induced cell death has long been considered as a double-edged sword that can inhibit or aggravate viral infections. However, understanding of the role of ferroptosis in various viral infections is limited. Special attention will be paid to the mechanisms of ferroptosis in mediating viral infection and antiviral treatment associated with ferroptosis. In this paper, we outlined the mechanism of ferroptosis. Additionally, this paper also review research on ferroptosis from the perspective of the virus, discussed the research status of ferroptosis in virus infection and classified and summarized research on the interaction between viral infections and ferroptosis.

Identification and validation of neutrophil-related biomarkers in acute-on-chronic liver failure

Dysfunction of peripheral blood neutrophils occurs in acute-on-chronic liver failure (ACLF). However, the molecular mechanisms of neutrophils involved in the pathophysiology of the ACLF remains poorly understood. Data downloaded from the GEO database (GSE142255) was used to identify both ACLF and neutrophil-related genes with the help of the limma package and Weighted Gene Co-Expression Network Analysis (WGCNA) algorithms. The analysis identified 288 ACLF-related differentially expressed genes (DEGs) in the circulating blood cells. Among these, three genes were found to be related to neutrophils and were identified as diagnostic genes, exhibiting high diagnostic efficacy as evidenced by an area under the curve (AUC) value of 1. Among these, matrix metallopeptidase-9 (MMP9) and S100 calcium binding protein A12 (S100A12) were upregulated, whereas C-C chemokine ligand 5 (CCL5) was downregulated in circulating immune cells from patients with ACLF compared to those from healthy controls. These findings were corroborated using an additional GEO dataset, GSE156382. The expression levels of the three key genes demonstrated a correlation with both ferroptosis and cuprotosis. Among the three diagnostic genes, only MMP9 was validated as differentially expressed through both quantitative real-time PCR (qRT-PCR) and western blot. Moreover, a significant elevation in plasma MMP9 levels was observed in patients with ACLF compared to those with chronic hepatitis B (CHB) and acute decompensated cirrhosis (AD). Notably, ACLF patients exhibiting elevated MMP9 levels (>175.8 ng/mL) experienced higher short-term mortality rates within both 30 and 90 days (p<0.001). In addition, a total of 21 drugs targeting the three diagnostic genes were identified from the Drug Bank database. Finally, the Kinase-TF-mRNA-miRNA network was constructed utilizing Cytoscape software. This study represents the initial application of WGCNA algorithms to identify novel biomarkers related to neutrophils in ACLF. Our findings offer new perspectives on the role of neutrophil in the pathogenesis of ACLF. However, additional research is required to substantiate the effects of these key genes and therapeutic agents on ACLF.

[Inhibiting Yes-associated protein alleviates CCl4 liver fibrosis in mice by reducing epithelial mesenchymal transition]

OBJECTIVE

To explore whether Yes-associated protein (YAP) affects occurrence and progression of liver fibrosis by regulating epithelial-mesenchymal transition (EMT).

METHODS

In a 8-week-old C57BL/6 mouse model of CCl4-induced liver fibrosis, the effect of verteporfin (a YAP inhibitor) intervention was assessed with HE staining and by detecting liver biochemistry and expressions of YAP and EMT-related genes using immunohistochemistry and Western blotting. Transcriptome and proteomic sequencing and informatics analysis were used to investigate the main downstream pathways of YAP in liver fibrosis. Serum levels of YAP, N-cadherin, vimentin and Twist were examined in 60 healthy individuals, 60 patients with chronic hepatitis B (CHB), and 60 patients with HBV-related liver cirrhosis. In another 24 C57BL/6 mice, the effects of Twist inhibitor alone or in combination with harmine (a YAP activator) on CCl4-induced liver fibrosis were evaluated by histopathological examination and Western blotting.

RESULTS

The mouse models of liver fibrosis showed obvious structural damages of the liver lobes with formation of pseudolobules, and verteporfin treatment significantly improved these pathologies and lowered plasma ALT and AST levels of the mice. Transcriptome and proteomic sequencing and informatics analysis suggested that N-cadherin and Twist were differentially expressed in liver fibrosis in close correlation with YAP. Inhibition of YAP obviously downregulated hepatic N-cadherin and Twist protein expressions in the mice with liver fibrosis. In patients with CHB and liver cirrhosis, serum levels of YAP elevated obviously with the severity of liver fibrosis and were significantly correlated with N-cadherin, vimentin and Twist levels. In mice with liver fibrosis, inhibiting Twist effectively improved liver inflammation and fibrosis, while the combined treatment with YAP activator worsened hepatic collagen fiber deposition and increased hepatic YAP and α-SMA expressions.

CONCLUSION

EMT is an important pathogenic mechanism of liver fibrosis, and inhibiting YAP can alleviate liver fibrosis by reducing EMT.

Yes-associated protein inhibition ameliorates carbon tetrachloride-induced acute liver injury in mice by reducing VDR

Carbon tetrachloride (CCl4) has a wide range of toxic effects, especially causing acute liver injury (ALI), in which rapid compensation for hepatocyte loss ensures liver survival, but proliferation of surviving hepatocytes (known as endoreplication) may imply impaired residual function. Yes-associated protein (YAP) drives hepatocytes to undergo endoreplication and ploidy, the underlying mechanisms of which remain a mystery. In the present study, we uncover during CCl4-mediated ALI accompanied by increased hepatocytes proliferation and YAP activation. Notably, bioinformatics analyses elucidate that hepatic-specific deletion of YAP substantially ameliorated CCl4-induced hepatic proliferation, effectively decreased the vitamin D receptor (VDR) expression. Additionally, a mouse model of acute liver injury substantiated that inhibition of YAP could suppress hepatocytes proliferation via VDR. Furthermore, we also disclosed that the VDR agonist nullifies CCl4-induced ALI alleviated by the YAP inhibitor in vivo. Importantly, hepatocytes were isolated from mice, and it was spotlighted that the anti-proliferative impact of the YAP inhibitor was abolished by the activation of VDR within these hepatocytes. Similarly, primary hepatic stellate cells (HSCs) were isolated and it was manifested that YAP inhibitor suppressed HSC activation via VDR during acute liver injury. Our findings further elucidate the YAP's role in ALI and may provide new avenues for protection against CCl4-drived acute liver injury.

Role of Hippo pathway dysregulation from gastrointestinal premalignant lesions to cancer

BACKGROUND

First identified in Drosophila melanogaster, the Hippo pathway is considered a major regulatory cascade controlling tissue homeostasis and organ development. Hippo signaling components include kinases whose activity regulates YAP and TAZ final effectors. In response to upstream stimuli, YAP and TAZ control transcriptional programs involved in cell proliferation, cytoskeletal reorganization and stemness.

MAIN TEXT

While fine tuning of Hippo cascade components is essential for maintaining the balance between proliferative and non-proliferative signals, pathway signaling is frequently dysregulated in gastrointestinal cancers. Also, YAP/TAZ aberrant activation has been described in conditions characterized by chronic inflammation that precede cancer development, suggesting a role of Hippo effectors in triggering carcinogenesis. In this review, we summarize the architecture of the Hippo pathway and discuss the involvement of signaling cascade unbalances in premalignant lesions of the gastrointestinal tract, providing a focus on the underlying molecular mechanisms.

CONCLUSIONS

The biology of premalignant Hippo signaling dysregulation needs further investigation in order to elucidate the evolutionary trajectories triggering cancer inititation and develop effective early therapeutic strategies targeting the Hippo/YAP pathway.

Ferroptosis as a Potential Therapeutic Target for Reducing Inflammation and Corneal Scarring in Bacterial Keratitis

Purpose

Bacterial keratitis (BK) is a serious ocular infection that can cause severe inflammation and corneal scarring, leading to vision loss. In this study, we aimed to investigate the involvement of ferroptosis in the pathogenesis of BK.

Methods

Transcriptome analysis was performed to evaluate ferroptosis-related gene expression in human BK corneas. Subsequently, the ferroptosis in mouse models of Pseudomonas aeruginosa keratitis and corneal stromal stem cells (CSSCs) were validated. The mice were treated with levofloxacin (LEV) or levofloxacin combined with ferrostatin-1 (LEV+Fer-1). CSSCs were treated with lipopolysaccharide (LPS) or LPS combined Fer-1. Inflammatory cytokines, α-SMA, and ferroptosis-related regulators were evaluated by RT-qPCR, immunostaining, and Western blot. Iron and reactive oxygen species (ROS) were measured.

Results

Transcriptome analysis revealed significant alterations in ferroptosis-related genes in human BK corneas. In the BK mouse models, the group treated with LEV+Fer-1 exhibited reduced inflammatory cytokines (MPO, TNF-α, and IFN-γ), decreased corneal scarring and α-SMA expression, and lower Fe3+ compared to the BK and LEV groups. Notably, the LEV+Fer-1 group showed elevated GPX4 and SLC7A11 in contrast to the BK and LEV group. In vitro, Fer-1 treatment effectively restored the alterations of ROS, Fe2+, GPX4, and SLC7A11 induced by LPS in CSSCs.

Conclusions

Ferroptosis plays a crucial role in the pathogenesis of BK. The inhibition of ferroptosis holds promise for mitigating inflammation, reducing corneal scarring, and ultimately enhancing the prognosis of BK. Consequently, this study provides a potential target for innovative therapeutic strategies for BK, which holds immense potential to transform the treatment of BK.

Targeting epigenetic and posttranslational modifications regulating ferroptosis for the treatment of diseases

Ferroptosis, a unique modality of cell death with mechanistic and morphological differences from other cell death modes, plays a pivotal role in regulating tumorigenesis and offers a new opportunity for modulating anticancer drug resistance. Aberrant epigenetic modifications and posttranslational modifications (PTMs) promote anticancer drug resistance, cancer progression, and metastasis. Accumulating studies indicate that epigenetic modifications can transcriptionally and translationally determine cancer cell vulnerability to ferroptosis and that ferroptosis functions as a driver in nervous system diseases (NSDs), cardiovascular diseases (CVDs), liver diseases, lung diseases, and kidney diseases. In this review, we first summarize the core molecular mechanisms of ferroptosis. Then, the roles of epigenetic processes, including histone PTMs, DNA methylation, and noncoding RNA regulation and PTMs, such as phosphorylation, ubiquitination, SUMOylation, acetylation, methylation, and ADP-ribosylation, are concisely discussed. The roles of epigenetic modifications and PTMs in ferroptosis regulation in the genesis of diseases, including cancers, NSD, CVDs, liver diseases, lung diseases, and kidney diseases, as well as the application of epigenetic and PTM modulators in the therapy of these diseases, are then discussed in detail. Elucidating the mechanisms of ferroptosis regulation mediated by epigenetic modifications and PTMs in cancer and other diseases will facilitate the development of promising combination therapeutic regimens containing epigenetic or PTM-targeting agents and ferroptosis inducers that can be used to overcome chemotherapeutic resistance in cancer and could be used to prevent other diseases. In addition, these mechanisms highlight potential therapeutic approaches to overcome chemoresistance in cancer or halt the genesis of other diseases.

Programmed Cell Death in Liver Fibrosis

Programmed cell death (PCD) is a comprehensive term that encompasses various forms of cell death, such as apoptosis, necroptosis, pyroptosis, ferroptosis, and autophagy, which play a crucial role in the pathogenesis of liver fibrosis. PCD facilitates the elimination of aberrant cells, particularly activated hepatic stellate cells (HSCs), which are the primary producers of extracellular matrix (ECM). The removal of HSCs may impede ECM synthesis, thereby mitigating liver fibrosis. As such, PCD has emerged as a promising therapeutic target for the development of novel drugs to treat liver fibrosis. Numerous studies have been conducted to investigate the underlying mechanisms of PCD in the elimination of activated HSCs and other aberrant liver cells in fibrotic liver tissue, including hepatocytes, hepatic sinusoid endothelial cells (LSECs), and Kupffer cells (KCs). The induction of PCD, the interplay between different forms of PCD, and the potential harm or benefit of PCD in liver fibrosis are topics of ongoing research. Evidences suggest that PCD is a complex process with dual effects on liver fibrosis. The purpose of this review is to summarize the most recent advances in PCD and liver fibrosis research.