Activation of YAP attenuates hepatic damage and fibrosis in liver ischemia-reperfusion injury

Icaritin attenuates ischemia-reperfusion injury by anti-inflammation, anti-oxidative stress, and anti-autophagy in mouse liver

BACKGROUND

Hepatic ischemia-reperfusion (IR) injury is a major complication of liver transplantation and gravely affects patient prognosis. Icaritin (ICT), the primary plasma metabolite of icariin (ICA), plays a critical role in anti-inflammatory and immunomodulatory processes. However, the role of ICT in hepatic IR injury remains largely undefined. In this study, we aimed to elucidate the role of ICT in hepatic IR injury.

METHODS

We established hepatic IR injury models in animals, as well as an oxygen-glucose deprivation/reperfusion (OGD/R) cell model. Liver injury in vivo was assessed by measuring serum alanine aminotransferase (ALT) levels, necrotic areas by liver histology and local hepatic inflammatory responses. For in vitro analyses, we implemented flow-cytometric and western blot analyses, transmission electron microscopy, and an mRFP-GFP-LC3 adenovirus reporter assay to assess the effects of ICT on OGD/R injury in AML12 and THLE-2 cell lines. Signaling pathways were explored in vitro and in vivo to identify possible mechanisms underlying ICT action in hepatic IR injury.

RESULTS

Compared to the mouse model group, ICT preconditioning considerably protected the liver against IR stress, and diminished the levels of necrosis/apoptosis and inflammation-related cytokines. In additional studies, ICT treatment dramatically boosted the expression ratios of p-PI3K/PI3K, p-AKT/AKT, and p-mTOR/mTOR proteins in hepatic cells following OGD/R damage. We also applied LY294002 (a PI3K inhibitor) and RAPA (rapamycin, an mTOR inhibitor), which blocked the protective effects of ICT in hepatocytes subjected to OGD/R.

CONCLUSION

This study indicates that ICT attenuates ischemia-reperfusion injury by exerting anti-inflammation, anti-oxidative stress, and anti-autophagy effects, as demonstrated in mouse livers. We thus posit that ICT could have therapeutic potential for the treatment of hepatic IR injury.

The deubiquitinase OTUD1 stabilizes NRF2 to alleviate hepatic ischemia/reperfusion injury

Hepatic ischemia/reperfusion (I/R) injury is an important cause of liver function impairment following liver surgery. The ubiquitin-proteasome system (UPS) plays a crucial role in protein quality control and has substantial impact on the hepatic I/R process. Although OTU deubiquitinase 1 (OTUD1) is involved in diverse biological processes, its specific functional implications in hepatic I/R are not yet fully understood. This study demonstrates that OTUD1 alleviates oxidative stress, apoptosis, and inflammation induced by hepatic I/R injury. Mechanistically, OTUD1 deubiquitinates and activates nuclear factor erythroid 2-related factor 2 (NRF2) through its catalytic site cysteine 320 residue and ETGE motif, thereby attenuating hepatic I/R injury. Additionally, administration of a short peptide containing the ETGE motif significantly mitigates hepatic I/R injury in mice. Overall, our study elucidates the mechanism and role of OTUD1 in ameliorating hepatic I/R injury, providing a theoretical basis for potential treatment using ETGE-peptide.

Regulation of YAP translocation by myeloid Pten deficiency alleviates acute lung injury via inhibition of oxidative stress and inflammation

BACKGROUND

Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is intricately involved in modulating the inflammatory response in acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). Nevertheless, the myeloid PTEN governing Hippo-YAP pathway mediated oxidative stress and inflammation in lipopolysaccharide (LPS)-induced ALI remains to be elucidate.

METHODS

The floxed Pten (PtenFL/FL) and myeloid-specific Pten knockout (PtenM-KO) mice were intratracheal instill LPS (5 mg/kg) to establish ALI, then Yap siRNA mix with the mannose-conjugated polymers was used to knockdown endogenous macrophage YAP in some PtenM-KO mice before LPS challenged. The bone marrow-derived macrophages (BMMs) from PtenFL/FL and PtenM-KO mice were obtained, and BMMs were transfected with CRISPR/Cas9-mediated glycogen synthase kinase 3 Beta (GSK3β) knockout (KO) or Yes-associated protein (YAP) KO vector subjected to LPS (100 ng/ml) challenged or then cocultured with MLE12 cells.

RESULTS

Here, our findings demonstrate that myeloid-specific PTEN deficiency exerts a protective against LPS-induced oxidative stress and inflammation dysregulated in ALI model. Moreover, ablation of the PTEN-YAP axis in macrophages results in reduced nuclear factor-E2-related factor-2 (NRF2) expression, a decrease in antioxidant gene expression, augmented levels of free radicals, lipid and protein peroxidation, heightened generation of pro-inflammatory cytokines, ultimately leading to increased apoptosis in MLE12 cells. Mechanistically, it is noteworthy that the deletion of myeloid PTEN promotes YAP translocation and regulates NRF2 expression, alleviating LPS-induced ALI via the inhibition of GSK3β and MST1 binding.

CONCLUSIONS

Our study underscores the crucial role of the myeloid PTEN-YAP-NRF2 axis in governing oxidative stress and inflammation dysregulated in ALI, indicating its potential as a therapeutic target for ALI.

Blockade of the mitochondrial DNA release ameliorates hepatic ischemia-reperfusion injury through avoiding the activation of cGAS-Sting pathway

BACKGROUND

Liver surgery during the perioperative period often leads to a significant complication known as hepatic ischemia-reperfusion (I/R) injury. Hepatic I/R injury is linked to the innate immune response. The cGAS-STING pathway triggers the activation of innate immune through the detection of DNA within cells. Nevertheless, the precise mechanism and significance of the cGAS-STING pathway in hepatic I/R injury are yet to be investigated.

METHODS

Mouse model of hepatic I/R injury was used in the C57BL/6 WT mice and the STING knockout (STING-KO) mice. In addition, purified primary hepatocytes were used to construct oxygen-glucose deprivation reperfusion (OGD-Rep) treatment models.

RESULTS

Our research revealed a notable increase in mRNA and protein levels of cGAS and STING in liver during I/R injury. Interestingly, the lack of STING exhibited a safeguarding impact on hepatic I/R injury by suppressing the elevation of liver enzymes, liver cell death, and inflammation. Furthermore, pharmacological cGAS and STING inhibition recapitulated these phenomena. Macrophages play a crucial role in the activation of the cGAS-STING pathway during hepatic I/R injury. The cGAS-STING pathway experiences a significant decrease in activity and hepatic I/R injury is greatly diminished following the elimination of macrophages. Significantly, we demonstrate that the activation of the cGAS-STING pathway is primarily caused by the liberation of mitochondrial DNA (mtDNA) rather than nuclear DNA (nDNA). Moreover, the safeguarding of the liver against I/R injury is also attributed to the hindrance of mtDNA release through the utilization of inhibitors targeting mPTP and VDAC oligomerization.

CONCLUSIONS

The results of our study suggest that the release of mtDNA plays a significant role in causing damage to liver by activating the cGAS-STING pathway during I/R injury. Furthermore, inhibiting the release of mtDNA can provide effective protection against hepatic I/R injury.

Angiotensin II depends on hippo/YAP signaling to reprogram angiogenesis and promote liver fibrosis

Liver fibrosis is a chronic pathological process in which the abnormal proliferation of connective tissue is induced by various pathogenic factors. During the process of fibrosis, excessive angiogenesis is observed. Physiological angiogenesis has the potential to impede the progression of liver fibrosis through augmenting matrix metalloenzyme activity; however, pathological angiogenesis can exacerbate liver fibrosis by promoting collagen accumulation. Therefore, a key scientific research focus in the treatment of liver diseases is to search for the "on-off" mechanism that regulates angiogenesis from normal proliferation to pathological proliferation. In this study, we found that excessive angiogenesis appeared during the initial phase of hepatic fibrosis without mesenchymal characteristics. In addition, angiogenesis accompanied by significant endothelial-to-mesenchymal transition (EndMT) was observed in mice after the intraperitoneal injection of angiotensin II (Ang II). Interestingly, the changes in Yes-associated protein (YAP) activity in endothelial cells (ECs) can affect the regulation of angiogenesis by Ang II. The results of in vitro experiments revealed that the regulatory influence of Ang II on ECs was significantly attenuated upon suppression of YAP activity. Furthermore, the function of Ang II in regulating angiogenesis during fibrosis was investigated in liver-specific transgenic mice. The results revealed that Ang II gene deletion could restrain liver fibrosis and EndMT. Meanwhile, Ang II deletion downregulated the profibrotic YAP signaling pathway in ECs. The small molecule AT1R agonist olmesartan targeting Ang II-YAP signaling could also alleviate liver fibrosis. In conclusion, this study identified Ang II as a pivotal regulator of EndMT during the progression of liver fibrosis and evaluated the therapeutic effect of the Ang II-targeted drug olmesartan on liver fibrosis.

A role for YAP/FOXM1/Nrf2 axis in oxidative stress and apoptosis of cataract induced by UVB irradiation

This study aims to investigate the hypothesis that Yes-associated protein (YAP) significantly regulates antioxidant potential and anti-apoptosis in UVB-induced cataract by exploring the underlying molecular mechanisms. To investigate the association between YAP and cataract, various experimental techniques were employed, including cell viability assessment, Annexin V FITC/PI assay, measurement of ROS production, RT-PCR, Western blot assay, and Immunoprecipitation. UVB exposure on human lens epithelium cells (HLECs) reduced total and nuclear YAP protein expression, increased cleaved/pro-caspase 3 ratios, decreased cell viability, and elevated ROS levels compared to controls. Similar Western blot results were observed in in vivo experiments involving UVB-treated mice. YAP knockdown in vitro demonstrated a decrease in the protein expression of FOXM1, Nrf2, and HO-1, which correlated with the mRNA expression, accompanied by an increase in cell apoptosis, caspase 3 activation, and the release of ROS. Conversely, YAP overexpression mitigated these effects induced by UVB irradiation. Immunoprecipitation revealed a FOXM1-YAP interaction. Notably, inhibiting FOXM1 decreased Nrf2 and HO-1, activating caspase 3. Additionally, administering the ROS inhibitor N-acetyl-L-cysteine (NAC) effectively mitigated the apoptotic effects induced by oxidative stress from UVB irradiation, rescuing the protein expression levels of YAP, FOXM1, Nrf2, and HO-1. The initial findings of our study demonstrate the existence of a feedback loop involving YAP, FOXM1, Nrf2, and ROS that significantly influences the cell apoptosis in HLECs under UVB-induced oxidative stress.

Ticlopidine protects hepatic ischemia-reperfusion injury via suppressing ferroptosis

Hepatic ischemia-reperfusion injury (IRI) is a major cause of liver damage during hepatic resection, transplantation, and other surgical procedures, often leading to graft failure and liver dysfunction. Recent studies have identified ferroptosis, a form of regulated cell death characterized by iron-dependent lipid peroxidation, as a key contributor to IRI. In this study, we investigated the protective effects of Ticlopidine, a thienopyridine compound and platelet aggregation inhibitor, on hepatic IRI. Using a C57BL/6J mouse model, we demonstrated that prophylactic Ticlopidine treatment significantly reduced necrotic and fibrotic areas in liver tissues, as well as serum levels of alanine transaminase (ALT) and aspartate aminotransferase (AST). Prussian Blue staining revealed that Ticlopidine pretreatment decreased iron accumulation in hepatic tissues, whereas markers of lipid peroxidation (malondialdehyde and 4-hydroxynonenal) and ferroptosis (PTGS2) were significantly downregulated. Additionally, Ticlopidine ameliorated inflammatory infiltration as indicated by reduced Gr-1 staining. In vitro, Ticlopidine dose-dependently inhibited ferroptosis induced by various inducers in liver cancer cell lines HUH7 and fibrosarcoma cells HT1080. The protective effects involved partial rescue of lipid peroxidation, significant reduction of ferrous iron levels, and strong protection against mitochondrial damage. These findings suggested that Ticlopidine acts as a broad-spectrum ferroptosis inhibitor, offering a promising therapeutic approach for protecting the liver against IRI.

Metabolic reprogramming in liver fibrosis

Chronic liver diseases, primarily metabolic dysfunction-associated steatotic liver disease (MASLD), harmful use of alcohol, or viral hepatitis, may result in liver fibrosis, cirrhosis, and cancer. Hepatic fibrogenesis is a complex process with interactions between different resident and non-resident heterogeneous liver cell populations, ultimately leading to deposition of extracellular matrix and organ failure. Shifts in cell phenotypes and functions involve pronounced transcriptional and protein synthesis changes that require metabolic adaptations in cellular substrate metabolism, including glucose and lipid metabolism, resembling changes associated with the Warburg effect in cancer cells. Cell activation and metabolic changes are regulated by metabolic stress responses, including the unfolded protein response, endoplasmic reticulum stress, autophagy, ferroptosis, and nuclear receptor signaling. These metabolic adaptations are crucial for inflammatory and fibrogenic activation of macrophages, lymphoid cells, and hepatic stellate cells. Modulation of these pathways, therefore, offers opportunities for novel therapeutic approaches to halt or even reverse liver fibrosis progression.

Inhibition of YAP/TAZ pathway contributes to the cytotoxicity of silibinin in MCF-7 and MDA-MB-231 human breast cancer cells

Breast cancer is one of the most common cancers threatening women's health. Our previous study found that silibinin induced the death of MCF-7 and MDA-MB-231 human breast cancer cells. We noticed that silibinin-induced cell damage was accompanied by morphological changes, including the increased cell aspect ratio (cell length/width) and decreased cell area. Besides, the cytoskeleton is also destroyed in cells treated with silibinin. YAP/TAZ, a mechanical signal sensor interacted with extracellular pressure, cell adhesion area and cytoskeleton, is also closely associated with cell survival, proliferation and migration. Thus, the involvement of YAP/TAZ in the cytotoxicity of silibinin in breast cancer cells has attracted our interests. Excitingly, we find that silibinin inhibits the nuclear translocation of YAP/TAZ in MCF-7 and MDA-MB-231 cells, and reduces the mRNA expressions of YAP/TAZ target genes, ACVR1, MnSOD and ANKRD. More importantly, expression of YAP1 gene is negatively correlated with the survival of the patients with breast cancers. Molecular docking analysis reveals high probabilities for binding of silibinin to the proteins in the YAP pathways. DARTS and CETSA results confirm the binding abilities of silibinin to YAP and LATS. Inhibiting YAP pathway either by addition of verteporfin, an inhibitor of YAP/TAZ-TEAD, or by transfection of si-RNAs targeting YAP or TAZ further enhances silibinin-induced cell damage. While enhancing YAP activity by silencing LATS1/2 or overexpressing YAPS127/397A, an active form of YAP, attenuates silibinin-induced cell damage. These findings demonstrate that inhibition of the YAP/TAZ pathway contributes to cytotoxicity of silibinin in breast cancers, shedding lights on YAP/TAZ-targeted cancer therapies.

Vitamin D3 attenuates autoimmune thyroiditis by regulating Th17/Treg cell differentiation via YAP/JAK1/STAT1 axis

BACKGROUND

Autoimmune thyroiditis (AITD) is an organ-specific autoimmune disease. Substantial evidence suggests that Vitamin D (VitD) deficiency is closely associated with an increased risk of AITD. However, the effects of VitD3 on immune cells, especially Th17/Treg cell subsets, and the underlying molecular mechanism in AITD have not yet been investigated.

METHODS

An experimental autoimmune thyroiditis (EAT) mouse model was established with a high-iodine diet. After 8 weeks, thyroid injury was assessed using hematoxylin and eosin (H&E) staining. ELISA was employed to measure serum levels of thyroxine (T3 and T4), thyroid autoimmune antibodies (Tg-Ab and TPO-Ab), and inflammatory cytokines. Flow cytometry and multiplex fluorescence immunohistochemical (mIHC) assays were used to analyze Th17/Treg cell subsets. The CCK-8 and flow cytometry assays were used to determine cell viability and apoptosis.

RESULTS

Administration of VitD3 reduced thyroid follicle destruction, decreased lymphocyte infiltration, and lowered T3, T4, Tg-Ab, and TPO-Ab serum levels in EAT mice. VitD3 treatment also reduced the frequency of Th17 cells while promoting the Treg cell subset both in the thyroid tissue and in the splenocytes cultured in vitro. Furthermore, VitD3 administration suppressed the production of inflammatory cytokines in EAT mice. VitD3 was also found to regulate Treg cells' differentiation, viability, and apoptosis. Mechanistically, we discovered that VitD3 treatment upregulated YAP expression and activated the JAK/STAT pathway. Rescue assays confirmed that depletion of YAP counteracted the effects of VitD3 on Treg cell differentiation and function.

CONCLUSION

Vitamin D3 attenuates AITD by modulating Th17/Treg cell balance via regulating the YAP/JAK1/STAT1 axis.

Inhibition of cysteine-serine-rich nuclear protein 1 ameliorates ischemia-reperfusion injury during liver transplantation in an MAPK-dependent manner

Hepatic ischemia-reperfusion injury (HIRI) is a critical pathophysiological process during liver transplantation (LT). Multiple genes and signal pathways are dysregulated during HIRI. This study aims to identify genes as potential therapeutic targets for ameliorating HIRI. Datasets containing samples from the human donor liver (GSE151648) and mouse HIRI model (GSE117066) were analyzed to determine differentially expressed genes (DEGs). The selected DEGs were confirmed by real-time PCR and western blot in the hepatocyte hypoxia-reoxygenation (HR) model, mouse HIRI model, and human liver samples after transplantation. Genetic inhibition was used to further clarify the underlying mechanism of the gene in vitro and in vivo. Among the DEGs, CSRNP1 was significantly upregulated (|log FC|= 2.08, P < 0.001), and was positively correlated with the MAPK signal pathway (R = 0.67, P < 0.001). CSRNP1 inhibition by siRNA significantly suppressed apoptosis in the AML-12 cell line after HR (mean Annexin+ ratio = 60.62% vs 42.47%, P = 0.0019), but the protective effect was eliminated with an additional MAPK activator. Knocking down CSRNP1 gene expression by intravenous injection of AAV-shRNA markedly reduced liver injury in mouse HIRI model (ALT: AAV-NC vs AAV-shCsrnp1 = 26,673.5 ± 2761.2 vs 3839.7 ± 1432.8, P < 0.001; AST: AAV-NC vs AAV-shCsrnp1 = 8640.5 ± 1450.3 vs 1786.8 ± 518.3, P < 0.001). Liver-targeted delivery of siRNA by nanoparticles effectively inhibited intra-hepatic genetic expression of Csrnp1 and alleviated IRI by reducing tissue inflammation and hepatocyte apoptosis. Furthermore, CSRNP1 inhibition was associated with reduced activation of the MAPK pathway both in vitro and in vivo. In conclusion, our results demonstrated that CSRNP1 could be a potential therapeutic target to ameliorate HIRI in an MAPK-dependent manner.

Gallic acid pretreatment mitigates parathyroid ischemia-reperfusion injury through signaling pathway modulation

Thyroid surgery often results in ischemia-reperfusion injury (IRI) to the parathyroid glands, yet the mechanisms underlying this and how to ameliorate IRI remain incompletely explored. Our study identifies a polyphenolic herbal extract-gallic acid (GA)-with antioxidative properties against IRI. Through flow cytometry and CCK8 assays, we investigate the protective effects of GA pretreatment on a parathyroid IRI model and decode its potential mechanisms via RNA-seq and bioinformatics analysis. Results reveal increased apoptosis, pronounced G1 phase arrest, and significantly reduced cell proliferation in the hypoxia/reoxygenation group compared to the hypoxia group, which GA pretreatment mitigates. RNA-seq and bioinformatics analysis indicate GA's modulation of various signaling pathways, including IL-17, AMPK, MAPK, transient receptor potential channels, cAMP, and Rap1. In summary, GA pretreatment demonstrates potential in protecting parathyroid cells from IRI by influencing various genes and signaling pathways. These findings offer a promising therapeutic strategy for hypoparathyroidism treatment.

Interplay between YAP/TAZ and metabolic dysfunction-associated steatotic liver disease progression

Metabolic dysfunction-associated steatotic liver disease (MASLD) is becoming an increasingly pressing global health challenge, with increasing mortality rates showing an upward trend. Two million deaths occur annually from cirrhosis and liver cancer together each year. Yes-associated protein (YAP) and transcriptional coactivator with PDZ-binding motif (TAZ), key effectors of the Hippo signaling pathway, critically regulate tissue homeostasis and disease progression in the liver. While initial studies have shown that YAP expression is normally restricted to cholangiocytes in healthy livers, the activation of YAP/TAZ is observed in other hepatic cells during chronic liver disease. The disease-driven dysregulation of YAP/TAZ appears to be a critical element in the MASLD progression, contributing to hepatocyte dysfunction, inflammation, and fibrosis. In this study, we focused on the complex roles of YAP/TAZ in MASLD and explored how the YAP/TAZ dysregulation of YAP/TAZ drives steatosis, inflammation, fibrosis, and cirrhosis. Finally, the cell-type-specific functions of YAP/TAZ in different types of hepatic cells, such as hepatocytes, hepatic stellate cells, hepatic macrophages, and biliary epithelial cells are discussed, highlighting the multifaceted impact of YAP/TAZ on liver physiology and pathology.

Angiotensin II type-2 receptor signaling facilitates liver injury repair and regeneration via inactivation of Hippo pathway

The angiotensin II type 2 receptor (AT2R) is a well-established component of the renin-angiotensin system and is known to counteract classical activation of this system and protect against organ damage. Pharmacological activation of the AT2R has significant therapeutic benefits, including vasodilation, natriuresis, anti-inflammatory activity, and improved insulin sensitivity. However, the precise biological functions of the AT2R in maintaining homeostasis in liver tissue remain largely unexplored. In this study, we found that the AT2R facilitates liver repair and regeneration following acute injury by deactivating Hippo signaling and that interleukin-6 transcriptionally upregulates expression of the AT2R in hepatocytes through STAT3 acting as a transcription activator binding to promoter regions of the AT2R. Subsequently, elevated AT2R levels activate downstream signaling via heterotrimeric G protein Gα12/13-coupled signals to induce Yap activity, thereby contributing to repair and regeneration processes in the liver. Conversely, a deficiency in the AT2R attenuates regeneration of the liver while increasing susceptibility to acetaminophen-induced liver injury. Administration of an AT2R agonist significantly enhances the repair and regeneration capacity of injured liver tissue. Our findings suggest that the AT2R acts as an upstream regulator in the Hippo pathway and is a potential target in the treatment of liver damage.

BTLA deficiency promotes HSC activation and protects against hepatic ischemia-reperfusion injury

BACKGROUND AND AIMS

Hepatic ischemia-reperfusion injury (IRI) is unavoidable even despite the development of more effective surgical approaches. During hepatic IRI, activated HSC (aHSC) are involved in liver injury and recovery.

APPROACH AND RESULT

A proportion of aHSC increased significantly both in the mouse liver tissues with IRI and in the primary mouse HSCs and LX-2 cells during hypoxia-reoxygenation. "Loss-of-function" experiments revealed that depleting aHSC with gliotoxin exacerbated liver damage in IRI mice. Subsequently, we found that the transcription of mRNA and the expression of B and T lymphocyte attenuator (BTLA) protein were lower in aHSC compared with quiescent HSCs. Interestingly, overexpression or knockdown of BTLA resulted in opposite changes in the activation of specific markers for HSCs such as collagen type I alpha 1, α-smooth muscle actin, and Vimentin. Moreover, the upregulation of these markers was also observed in the liver tissues of global BLTA-deficient (BTLA-/-) mice and was higher after hepatic IRI. Compared with wild-type mice, aHSC were higher, and liver injury was lower in BTLA-/- mice following IRI. However, the depletion of aHSC reversed these effects. In addition, the depletion of aHSC significantly exacerbated liver damage in BTLA-/- mice with hepatic IRI. Furthermore, the TGF-β1 signaling pathway was identified as a potential mechanism for BTLA to negatively regulate the activation of HSCs in vivo and in vitro.

CONCLUSIONS

These novel findings revealed a critical role of BTLA. Particularly, the receptor inhibits HSC-activated signaling in acute IRI, implying that it is a potential immunotherapeutic target for decreasing the IRI risk.

RASSF4 Attenuates Metabolic Dysfunction-Associated Steatotic Liver Disease Progression via Hippo Signaling and Suppresses Hepatocarcinogenesis

BACKGROUND & AIMS

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a dynamic chronic liver disease closely related to metabolic abnormalities such as diabetes and obesity. MASLD can further progress to metabolic dysfunction-associated steatohepatitis (MASH), fibrosis, cirrhosis, and even hepatocellular carcinoma (HCC). However, the mechanisms underlying the progression of MASLD and further progression to liver fibrosis and liver cancer are unknown.

METHODS

In this study, we performed transcriptome analysis in livers from mice with MASLD and found suppression of a potential anti-oncogene, RAS association domain protein 4 (RASSF4). RASSF4 expression levels were measured in liver or tumor tissues of patients with MASH or HCC, respectively. We established RASSF4 overexpression and knockout mouse models. The effects of RASSF4 were evaluated by quantitative polymerase chain reaction, Western blotting, histopathological analysis, wound healing assays, Transwell assays, EdU incorporation assays, colony formation assays, sorafenib sensitivity assays, and tumorigenesis assays.

RESULTS

RASSF4 was significantly down-regulated in MASH and HCC samples. Using liver-specific RASSF4 knockout mice, we demonstrated that loss of hepatic RASSF4 exacerbated hepatic steatosis and fibrosis. In contrast, RASSF4 overexpression prevented steatosis in MASLD mice. In addition, RASSF4 in hepatocytes suppressed the activation of hepatic stellate cells (HSCs) by reducing transforming growth factor beta secretion. Moreover, we found that RASSF4 is an independent prognostic factor for HCC. Mechanistically, we found that RASSF4 in the liver interacts with MST1 to inhibit YAP nuclear translocation through the Hippo pathway.

CONCLUSIONS

These findings establish RASSF4 as a therapeutic target for MASLD and HCC.

Gut microbiota-derived gamma-aminobutyric acid from metformin treatment reduces hepatic ischemia/reperfusion injury through inhibiting ferroptosis

Hepatic ischemia/reperfusion injury (HIRI) is a common and inevitable factor leading to poor prognosis in various liver diseases, making the outcomes of current treatments in clinic unsatisfactory. Metformin has been demonstrated to be beneficial to alleviate HIRI in recent studies, however, the underpinning mechanism remains unclear. In this study, we found metformin mitigates HIRI-induced ferroptosis through reshaped gut microbiota in mice, which was confirmed by the results of fecal microbiota transplantation treatment but showed the elimination of the beneficial effects when gut bacteria were depleted using antibiotics. Detailedly, through 16S rRNA and metagenomic sequencing, we identified that the metformin-reshaped microbiota was characterized by the increase of gamma-aminobutyric acid (GABA) producing bacteria. This increase was further confirmed by the elevation of GABA synthesis key enzymes, glutamic acid decarboxylase and putrescine aminotransferase, in gut microbes of metformin-treated mice and healthy volunteers. Furthermore, the benefit of GABA against HIRI-induced ferroptosis was demonstrated in GABA-treated mice. Collectively, our data indicate that metformin can mitigate HIRI-induced ferroptosis by reshaped gut microbiota, with GABA identified as a key metabolite.

BMX deletion mitigates neuroinflammation induced by retinal ischemia/reperfusion through modulation of the AKT/ERK/STAT3 signaling cascade

Aims

Retinal ischemia/reperfusion (I/R) injury is implicated in the etiology of various ocular disorders. Prior research has demonstrated that bone marrow tyrosine kinase on chromosome X (BMX) contributes to the advancement of ischemic disease and inflammatory reactions. Consequently, the current investigation aims to evaluate BMX's impact on retinal I/R injury and clarify its implied mechanism of action.

Main methods

This study utilized male and female systemic BMX knockout (BMX-/-) mice to conduct experiments. The utilization of Western blot assay and immunofluorescence labeling techniques was employed to investigate variations in the expression of protein and tissue localization. Histomorphological changes were observed through H&E staining and SD-OCT examination. Visual function changes were assessed through electrophysiological experiments. Furthermore, apoptosis in the retina was identified using the TUNEL assay, as well as the ELISA technique, which has been utilized to determine the inflammatory factors level.

Key findings

Our investigation results revealed that the knockdown of BMX did not yield a significant effect on mouse retina. In mice, BMX knockdown mitigated the negative impact of I/R injury on retinal tissue structure and visual function. BMX knockdown effectively reduced apoptosis, suppressed inflammatory responses, and decreased inflammatory factors subsequent to I/R injury. The outcomes of the current investigation revealed that BMX knockdown partially protected the retina through downregulating phosphorylation of AKT/ERK/STAT3 pathway.

Significance

Our investigation showed that BMX-/- reduces AKT, ERK, and STAT3 phosphorylation, reducing apoptosis and inflammation. Thus, this strategy protected the retina from structural and functional damage after I/R injury.

GRK2 mediated degradation of SAV1 initiates hyperplasia of fibroblast-like synoviocytes in rheumatoid arthritis

Hyperplasia and migration of fibroblast-like synoviocytes (FLSs) are the key drivers in the pathogenesis of rheumatoid arthritis (RA) and joint destruction. Abundant Yes-associated protein (YAP), which is a powerful transcription co-activator for proliferative genes, was observed in the nucleus of inflammatory FLSs with unknown upstream mechanisms. Using Gene Expression Omnibus database analysis, it was found that Salvador homolog-1 (SAV1), the pivotal negative regulator of the Hippo-YAP pathway, was slightly downregulated in RA synovium. However, SAV1 protein expression is extremely reduced. Subsequently, it was revealed that SAV1 is phosphorylated, ubiquitinated, and degraded by interacting with an important serine-threonine kinase, G protein-coupled receptor (GPCR) kinase 2 (GRK2), which was predominately upregulated by GPCR activation induced by ligands such as prostaglandin E2 (PGE2) in RA. This process further contributes to the decreased phosphorylation, nuclear translocation, and transcriptional potency of YAP, and leads to aberrant FLSs proliferation. Genetic depletion of GRK2 or inhibition of GRK2 by paroxetine rescued SAV1 expression and restored YAP phosphorylation and finally inhibited RA FLSs proliferation and migration. Similarly, paroxetine treatment effectively reduced the abnormal proliferation of FLSs in a rat model of collagen-induced arthritis which was accompanied by a significant improvement in clinical manifestations. Collectively, these results elucidate the significance of GRK2 regulation of Hippo-YAP signaling in FLSs proliferation and migration and the potential application of GRK2 inhibition in the treatment of FLSs-driven joint destruction in RA.

Abnormal metabolism in hepatic stellate cells: Pandora's box of MAFLD related hepatocellular carcinoma

Metabolic associated fatty liver disease (MAFLD) is a significant risk factor for the development of hepatocellular carcinoma (HCC). Hepatic stellate cells (HSCs), as key mediators in liver injury response, are believed to play a crucial role in the repair process of liver injury. However, in MAFLD patients, the normal metabolic and immunoregulatory mechanisms of HSCs become disrupted, leading to disturbances in the local microenvironment. Abnormally activated HSCs are heavily involved in the initiation and progression of HCC. The metabolic disorders and abnormal activation of HSCs not only initiate liver fibrosis but also contribute to carcinogenesis. In this review, we provide an overview of recent research progress on the relationship between the abnormal metabolism of HSCs and the local immune system in the liver, elucidating the mechanisms of immune imbalance caused by abnormally activated HSCs in MAFLD patients. Based on this understanding, we discuss the potential and challenges of metabolic-based and immunology-based mechanisms in the treatment of MAFLD-related HCC, with a specific focus on the role of HSCs in HCC progression and their potential as targets for anti-cancer therapy. This review aims to enhance researchers' understanding of the importance of HSCs in maintaining normal liver function and highlights the significance of HSCs in the progression of MAFLD-related HCC.

Endothelial YAP/TEAD1-CXCL17 signaling recruits myeloid-derived suppressor cells against liver ischemia-reperfusion injury

BACKGROUND AND AIMS

Liver ischemia-reperfusion injury (IRI) is a common complication of liver transplantation and hepatectomy and causes acute liver dysfunction and even organ failure. Myeloid-derived suppressor cells (MDSCs) accumulate and play immunosuppressive function in cancers and inflammation. However, the role of MDSCs in liver IRI has not been defined.

APPROACH AND RESULTS

We enrolled recipients receiving OLT and obtained the pre-OLT/post-OLT blood and liver samples. The proportions of MDSCs were significantly elevated after OLT and negatively associated with liver damage. In single-cell RNA-sequencing analysis of liver samples during OLT, 2 cell clusters with MDSC-like phenotypes were identified and showed maturation and infiltration in post-OLT livers. In the mouse model, liver IRI mobilized MDSCs and promoted their infiltration in the damaged liver, and intrahepatic MDSCs were possessed with enhanced immunosuppressive function by upregulation of STAT3 signaling. Under treatment with αGr-1 antibody or adoptive transfer MDSCs to change the proportion of MDSCs in vivo, we found that intrahepatic MDSCs alleviated liver IRI-induced inflammation and damage by inhibiting M1 macrophage polarization. Mechanistically, bulk RNA-sequencing analysis and in vivo experiments verified that C-X-C motif chemokine ligand 17 (CXCL17) was upregulated by YAP/TEAD1 signaling and subsequently recruited MDSCs through binding with GPR35 during liver IRI. Moreover, hepatic endothelial cells were the major cells responsible for CXCL17 expression in injured livers, among which hypoxia-reoxygenation stimulation activated the YAP/TEAD1 complex to promote CXCL17 transcription.

CONCLUSIONS

Endothelial YAP/TEAD1-CXCL17 signaling recruited MDSCs to attenuate liver IRI, providing evidence of therapeutic potential for managing IRI in liver surgery.

Inhibition of Sirt3 activates the cGAS-STING pathway to aggravate hepatocyte damage in hepatic ischemia-reperfusion injury mice

Hepatic ischemia-reperfusion injury (IRI) typically manifests during subtotal hepatectomy and inflicts substantial damage to liver function in the perioperative period. Although the central role of cGAS-STING-mediated immune inflammation in hepatocyte damage during hepatic IRI is acknowledged, the precise regulatory mechanisms remain elusive. The current study aims to elucidate how Sirt3 inhibition activates the cGAS-STING pathway and exacerbates hepatocyte damage in hepatic IRI. We established both in vivo and in vitro models by creating hepatic IRI mice model and subjecting AML-12 hepatocyte cell lines to oxygen-glucose deprivation/reperfusion (OGD/R). Hepatic IRI compromised liver and mitochondrial function while elevating cytosolic mitochondrial DNA (mtDNA) levels in hepatocytes. Additionally, both in vivo hepatic IRI and in vitro OGD/R induced increased phosphorylation and activation of cGAS, STING, and IRF3, accompanied by heightened levels of pro-inflammatory factors, including TNF-α, IL-1β, and type I interferon (IFN-β). Importantly, knockdown of cGAS or STING through siRNA effectively attenuated hepatic IRI-induced inflammation and ameliorated liver function in both experimental settings, underscoring the dynamic involvement of the cGAS-STING pathway in hepatic IRI-induced inflammation. Furthermore, we observed a significant reduction in Sirt3 expression following hepatic IRI, both in vivo and in vitro. Then we generated Sirt3-deficient mice and applied Sirt3 knockdown in AML-12 hepatocytes. Notably, Sirt3 deficiency led to increased phosphorylation and activation of cGAS, STING, and IRF3, coupled with elevated TNF-α, IL-1β, and IFN-β levels in both in vivo and in vitro conditions. Moreover, upon silencing various downstream targets of Sirt3, such as transcription factors Sp1, Pu1, and p65, we observed that specifically knocking down p65 in AML-12 hepatocytes reduced cGAS mRNA levels. Co-immunoprecipitation assays confirmed a direct interaction between Sirt3 and p65. The absence of Sirt3 significantly increased nuclear translocation of p65 in mice, whereas Sirt3 knockdown in AML-12 hepatocytes heightened nuclear translocation of p65. ChIP-PCR assays demonstrated that Sirt3 deficiency notably enhanced the binding of p65 to two cGAS promoters, ultimately promoting cGAS transcription. Collectively, our results underscored that inhibition of Sirt3 activates the cGAS-STING pathway to aggravate hepatocyte damage by increasing cytosolic mtDNA and promoting nuclear translocation of p65 to promote cGAS transcription in hepatic IRI. These findings hold promise for potential therapeutic interventions in hepatic IRI by targeting the Sirt3-cGAS-STING axis, offering new avenues for the development of clinical strategies to mitigate liver damage during the perioperative period.

Modification of Preservative Fluids with Antioxidants in Terms of Their Efficacy in Liver Protection before Transplantation

Transplantation is currently the only effective treatment for patients with end-stage liver failure. In recent years, many advanced studies have been conducted to improve the efficiency of organ preservation techniques. Modifying the composition of the preservation fluids currently used may improve graft function and increase the likelihood of transplantation success. The modified fluid is expected to extend the period of safe liver storage in the peri-transplantation period and to increase the pool of organs for transplantation with livers from marginal donors. This paper provides a literature review of the effects of antioxidants on the efficacy of liver preservation fluids. Medline (PubMed), Scopus, and Cochrane Library databases were searched using a combination of MeSH terms: "liver preservation", "transplantation", "preservation solution", "antioxidant", "cold storage", "mechanical perfusion", "oxidative stress", "ischemia-reperfusion injury". Studies published up to December 2023 were included in the analysis, with a focus on publications from the last 30 years. A total of 45 studies met the inclusion criteria. The chemical compounds analyzed showed mostly bioprotective effects on hepatocytes, including but not limited to multifactorial antioxidant and free radical protective effects. It should be noted that most of the information cited is from reports of studies conducted in animal models, most of them in rodents.

The inhibition of YAP Signaling Prevents Chronic Biliary Fibrosis in the Abcb4-/- Model by Modulation of Hepatic Stellate Cell and Bile Duct Epithelium Cell Pathophysiology

Primary sclerosing cholangitis (PSC) represents a chronic liver disease characterized by poor prognosis and lacking causal treatment options. Yes-associated protein (YAP) functions as a critical mediator of fibrogenesis; however, its therapeutic potential in chronic biliary diseases such as PSC remains unestablished. The objective of this study is to elucidate the possible significance of YAP inhibition in biliary fibrosis by examining the pathophysiology of hepatic stellate cells (HSC) and biliary epithelial cells (BEC). Human liver tissue samples from PSC patients were analyzed to assess the expression of YAP/connective tissue growth factor (CTGF) relative to non-fibrotic control samples. The pathophysiological relevance of YAP/CTGF in HSC and BEC was investigated in primary human HSC (phHSC), LX-2, H69, and TFK-1 cell lines through siRNA or pharmacological inhibition utilizing verteporfin (VP) and metformin (MF). The Abcb4-/- mouse model was employed to evaluate the protective effects of pharmacological YAP inhibition. Hanging droplet and 3D matrigel culture techniques were utilized to investigate YAP expression and activation status of phHSC under various physical conditions. YAP/CTGF upregulation was observed in PSC patients. Silencing YAP/CTGF led to inhibition of phHSC activation and reduced contractility of LX-2 cells, as well as suppression of epithelial-mesenchymal transition (EMT) in H69 cells and proliferation of TFK-1 cells. Pharmacological inhibition of YAP mitigated chronic liver fibrosis in vivo and diminished ductular reaction and EMT. YAP expression in phHSC was effectively modulated by altering extracellular stiffness, highlighting YAP's role as a mechanotransducer. In conclusion, YAP regulates the activation of HSC and EMT in BEC, thereby functioning as a checkpoint of fibrogenesis in chronic cholestasis. Both VP and MF demonstrate effectiveness as YAP inhibitors, capable of inhibiting biliary fibrosis. These findings suggest that VP and MF warrant further investigation as potential therapeutic options for the treatment of PSC.

PPM1G regulates hepatic ischemia/reperfusion injury through STING-mediated inflammatory pathways in macrophages

BACKGROUND

Ischemia/reperfusion injury (IRI) is generally unavoidable following liver transplantation. Here, we investigated the role of protein phosphatase, Mg2+ /Mn2+ dependent 1G (PPM1G) in hepatic IRI.

METHODS

Hepatic IRI was mimicked by employing a hypoxia/reperfusion (H/R) model in RAW 264.7 cells and a 70% warm ischemia model in C57BL/6 mice, respectively. In vitro, expression changes of tumor necrosis factor-α and interleukin were detected by quantitative real-time polymerase chain reaction (qRT-PCR), western blot analysis, and enzyme-linked immunosorbent assay. The protein expressions of PPM1G and the stimulator of interferon genes (STING) pathway components were analyzed by western blot. Interaction between PPM1G and STING was verified by coimmunoprecipitation (CO-IP). Immunofluorescence was applied for detection of p-IRF3. Flow cytometry, qRT-PCR and western blot were utilized to analyze markers of macrophage polarization. In vivo, histological analyses of mice liver were carried out by TUNEL and H&E staining. Changes in serum aminotransferases were also detected.

RESULTS

Following H/R intervention, a steady decline in PPM1G along with an increase in inflammatory cytokines in vitro was observed. Addition of plasmid with PPM1G sequence limited the release of inflammatory cytokines and downregulated phosphorylation of STING. CO-IP validated the interaction between PPM1G and STING. Furthermore, inhibition of PPM1G with lentivirus enhanced phosphorylation of STING and its downstream components; meanwhile, p65, p38, and Jnk were also surged to phosphorylation. Expression of INOS and CD86 was surged, while CD206, Arg-1, and IL-10 were inhibited. In vivo, PPM1G inhibition further promoted liver damage, hepatocyte apoptosis, and transaminases release. Selective inhibition of STING with C-176 partially reversed the activation of STING pathway and inflammatory cytokines in vitro. M1 markers were also suppressed by C-176. In vivo, C-176 rescued liver damage and transaminase release caused by PPM1G inhibition.

CONCLUSION

PPM1G suppresses hepatic IRI and macrophage M1 phenotype by repressing STING-mediated inflammatory pathways.

YAP promotes the healing of ischemic wounds by reducing ferroptosis in skin fibroblasts through inhibition of ferritinophagy

The impaired healing of chronic wounds is often attributed to the ischemic and hypoxic microenvironment, leading to increased cell death. Ferroptosis, a novel form of cell death unveiled in recent years, could potentially be linked with the process of wound healing. In this study, we explored the significance and mechanism of ferroptosis in ischemic wounds. Using transmission electron microscopy, Western blot, flow cytometry, immunofluorescence, and glutathione (GSH) assay, we observed that the death of primary mouse skin fibroblasts induced by oxygen and glucose deprivation (OGD) was associated with ferroptosis. Specifically, we observed elevated intracellular Fe2+ and lipid peroxidation levels and decreased GSH levels in vitro, indicative of ferroptosis. Importantly, we found that ferroptosis in OGD-treated skin fibroblasts was dependent on autophagy, as the autophagy inhibitor chloroquine phosphate (CHQ) significantly reduced ferroptosis induced by OGD. Moreover, our study revealed that NCOA4-mediated ferritinophagy significantly contributed to the occurrence of ferroptosis induced by OGD in skin fibroblasts. Additionally, we identified the involvement of YAP in the regulation of ferritinophagy, with YAP suppressing NCOA4 expression in OGD-treated skin fibroblasts, thereby reducing ferroptosis. Furthermore, in ischemic wound models in mice, both inhibitors of ferroptosis and autophagy promoted wound healing, while a YAP inhibitor, verteporfin, delayed wound healing. In conclusion, these findings indicate that ferroptosis, regulated by YAP through ferritinophagy inhibition, presents a novel mechanism responsible for the delayed healing of ischemic wounds. Understanding this process could offer promising therapeutic targets to improve wound healing in ischemic conditions.

Zinc Oxide Nanoparticles Ameliorate Histological Alterations Through Apoptotic Gene Regulation in Rat Model of Liver Ischemia-Reperfusion Injury

Background

Organ ischemia-reperfusion (IR) is a common clinical condition associated with various situations such as trauma surgery, organ transplantation, and myocardial ischemia. Current therapeutic methods for IR injury have limitations, and nanotechnology, particularly zinc oxide nanoparticles (ZnO NPs), offers new approaches for disease diagnosis and treatment. In this study, we investigated the protective and anti-apoptotic effects of ZnO NPs in liver ischemia-reperfusion (IR) injury in rats.

Methods

Forty-eight male rats were divided into six groups: sham, ZnO5, ZnO10, ischemia-reperfusion (IR), IR+ZnO5, and IR+ZnO10. The protective effect of ZnO NPs was evaluated by liver enzymes (AST, ALT, Bilirubin, ALP), biochemical (TAC, TNF-α, and MDA), molecular examinations (Bcl2, BAX), and histopathological evaluations (H&E, TUNEL).

Results

Pre-treatment with ZnO5 and ZnO10 improved hepatic function in IR liver injury, attenuated the levels of oxidants (P = 0.03) and inflammatory mediators, and reduced apoptosis (P = 0). ZnO10 was found to have a greater effect on ischemic reperfusion injury than ZnO5 did. Histopathological examination also showed a dose-dependent decrease in alterations in the IR+ZnO5 and IR+ZnO10 groups.

Conclusion

Administration of ZnO5 and ZnO10 improved liver function after IR. The findings of this study suggest that ZnO NPs have a protective effect against oxidative stress and apoptosis in liver ischemia-reperfusion injury in rats. These results may have important implications for developing advanced methods in ischemia-reperfusion treatment.

Nuclear deformation regulates YAP dynamics in cancer associated fibroblasts

Cells cultured on stiff 2D substrates exert high intracellular force, resulting in mechanical deformation of their nuclei. This nuclear deformation (ND) plays a crucial role in the transport of Yes Associated Protein (YAP) from the cytoplasm to the nucleus. However, cells in vivo are in soft 3D environment with potentially much lower intracellular forces. Whether and how cells may deform their nuclei in 3D for YAP localization remains unclear. Here, by culturing human colon cancer associated fibroblasts (CAFs) on 2D, 2.5D, and 3D substrates, we differentiated the effects of stiffness, force, and ND on YAP localization. We found that nuclear translocation of YAP depends on the degree of ND irrespective of dimensionality, stiffness and total force. ND induced by the perinuclear force, not the total force, and nuclear membrane curvature correlate strongly with YAP activation. Immunostained slices of human tumors further supported the association between ND and YAP nuclear localization, suggesting ND as a potential biomarker for YAP activation in tumors. Additionally, we conducted quantitative analysis of the force dynamics of CAFs on 2D substrates to construct a stochastic model of YAP kinetics. This model revealed that the probability of YAP nuclear translocation, as well as the residence time in the nucleus follow a power law. This study provides valuable insights into the regulatory mechanisms governing YAP dynamics and highlights the significance of threshold activation in YAP localization. STATEMENT OF SIGNIFICANCE: Yes Associated Protein (YAP), a transcription cofactor, has been identified as one of the drivers of cancer progression. High tumor stiffness is attributed to driving YAP to the nucleus, wherein it activates pro-metastatic genes. Here we show, using cancer associated fibroblasts, that YAP translocation to the nucleus depends on the degree of nuclear deformation, irrespective of stiffness. We also identified that perinuclear force induced membrane curvature correlates strongly with YAP nuclear transport. A novel stochastic model of YAP kinetics unveiled a power law relationship between the activation threshold and persistence time of YAP in the nucleus. Overall, this study provides novel insights into the regulatory mechanisms governing YAP dynamics and the probability of activation that is of immense clinical significance.

Neutrophil extracellular traps regulating tumorimmunity in hepatocellular carcinoma

As a component of the innate immune system, there is emerging evidence to suggest that neutrophils may play a critical role in the initiation and progression of hepatocellular carcinoma (HCC). Neutrophil extracellular traps (NETs) are web-like chromatin structures that protrude from the membranes during neutrophil activation. Recent research has shown that NETs, which are at the forefront of the renewed interest in neutrophil studies, are increasingly intertwined with HCC. By exploring the mechanisms of NETs in HCC, we aim to improve our understanding of the role of NETs and gain deeper insights into neutrophil biology. Therefore, this article provides a summary of key findings and discusses the emerging field of NETs in HCC.

Research progress of traditional Chinese medicine in improving hepatic fibrosis based on inhibiting pathological angiogenesis

Hepatic fibrosis is the formation of scar tissue in the liver. This scar tissue replaces healthy liver tissue and can lead to liver dysfunction and failure if left untreated. It is usually caused by chronic liver disease, such as hepatitis B or C, alcohol abuse, or non-alcoholic fatty liver disease. Pathological angiogenesis plays a crucial role in the development of hepatic fibrosis by promoting the growth of new blood vessels in the liver. These new vessels increase blood flow to the damaged areas of the liver, which triggers the activation of hepatic stellate cells (HSCs). HSCs are responsible for producing excess collagen and other extracellular matrix proteins that contribute to the development of fibrosis. Pathological angiogenesis plays a crucial role in the development of hepatic fibrosis by promoting the growth of new blood vessels in the liver. These new vessels increase blood flow to the damaged areas of the liver, which triggers the activation of HSCs. HSCs are responsible for producing excess collagen and other extracellular matrix proteins that contribute to the development of fibrosis. Traditional Chinese medicine (TCM) has been found to target pathological angiogenesis, thereby providing a potential treatment option for hepatic fibrosis. Several studies have demonstrated that TCM exhibits anti-angiogenic effects by inhibiting the production of pro-angiogenic factors, such as vascular endothelial growth factor and angiopoietin-2, and by reducing the proliferation of endothelial cells. Reviewing and highlighting the unique TCM recognition of treating hepatic fibrosis by targeting pathological angiogenesis may shed light on future hepatic fibrosis research.

Hepatic Stellate Cell- and Liver Microbiome-Specific Delivery System for Dihydrotanshinone I to Ameliorate Liver Fibrosis

Liver fibrosis is a major contributor to the morbidity and mortality associated with liver diseases, yet effective treatment options remain limited. Hepatic stellate cells (HSCs) are a promising target for hepatic fibrogenesis due to their pivotal role in disease progression. Our previous research has demonstrated the potential of Dihydrotanshinone I (DHI), a lipophilic component derived from the natural herb Salvia miltiorrhiza Bunge, in treating liver fibrosis by inhibiting the YAP/TEAD2 interaction in HSCs. However, the clinical application of DHI faces challenges due to its poor aqueous solubility and lack of specificity for HSCs. Additionally, recent studies have implicated the impact of liver microbiota, distinct from gut microbiota, on the pathogenesis of liver diseases. In this study, we have developed an HSC- and microbiome-specific delivery system for DHI by conjugating prebiotic-like cyclodextrin (CD) with vitamin A, utilizing PEG2000 as a linker (VAP2000@CD). Our results demonstrate that VAP2000@CD markedly enhances the cellular uptake in human HSC line LX-2 and enhances the deposition of DHI in the fibrotic liver in vivo. Subsequently, intervention with DHI-VAP2000@CD has shown a notable reduction in bile duct-like structure proliferation, collagen accumulation, and the expression of fibrogenesis-associated genes in rats subjected to bile duct ligation. These effects may be attributed to the regulation of the YAP/TEAD2 interaction. Importantly, the DHI-VAP2000@CD intervention has also restored microbial homeostasis in the liver, promoting the amelioration of liver inflammation. Overall, our findings indicate that DHI-VAP2000@CD represents a promising therapeutic approach for liver fibrosis by specifically targeting HSCs and restoring the liver microbial balance.

Identification of hub genes and potential inhibitory compounds in the process of liver transplantation through transcriptome sequencing

Liver transplantation (LT) is the best choice for patients with end-stage liver diseases. In order to better understand pathophysiological alterations in LT, we aimed to identify potential hub genes and inhibitory compounds involved in the LT process. Four pairs of peripheral blood mononuclear cell (PBMC) samples of the LT recipients before and after surgery were collected and taken for transcriptome sequencing. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were performed for the screened differentially expressed genes (DEGs) between pre- and post-operation groups. Common DEGs were obtained from GO and KEGG enriched pathways, followed by protein-protein interaction (PPI) network construction, hub gene identification, module analysis, and structure-based virtual screening process (SBVS). Compared to the pre-operation stage, 4745 genes were down-regulated and 798 up-regulated after LT. GO analysis showed that the DEGs were enriched in ribosome-related translation regulation, and KEGG analysis indicated that infection and immune-related pathways and diseases were largely enriched. A large number of down-regulated DEGs were not only associated with ribosome-related pathways but also with the alterations of epigenetic modifications, in particular ubiquitination. Moreover, through the PPI network of 29 common genes from GO and KEGG-enriched pathways, 7 hub genes were identified, including PTEN, MYC, EIF2S1, EIF4EBP1, HSP90AB1, TP53, and HSPA8, which were mainly involved in the PI3K-AKT signaling pathway. SBVS of the seed molecule PTEN (PDB code: 1D5R) predicted top hits compounds that may serve as potential inhibitors of PTEN, of which the compound ZINC4235331 had the lowest binding affinity of -10 kcal/mol. The significance of screened hub genes and potential inhibitors involved in the process of LT provides novel therapeutic strategies for improving the outcomes of LT recipients during surgery.

ROS/RNS as molecular signatures of chronic liver diseases

The liver can succumb to oxidant damage during the development of chronic liver diseases. Despite their physiological relevance to hepatic homeostasis, excessive reactive oxygen/nitrogen species (ROS/RNS) production under pathological conditions is detrimental to all liver constituents. Chronic oxidative stress coupled to unresolved inflammation sets in motion the activation of profibrogenic hepatic stellate cells (HSCs) and later pathogenesis of liver fibrosis, cirrhosis, and liver cancer. The liver antioxidant and repair systems, along with autophagic and ferroptotic machineries, are implicated in the onset and trajectory of disease development. In this review, we discuss the ROS/RNS-related mechanisms underlying liver fibrosis of distinct etiologies and highlight preclinical and clinical trials of antifibrotic therapies premised on remediating oxidative/nitrosative stress in hepatocytes or targeting HSC activation.

Hepatocellular SETDB1 Regulates Hepatic Ischemia-Reperfusion Injury through Targeting Lysine Methylation of ASK1 Signal

Background: Hepatic ischemia-reperfusion injury (HIRI) stands as an unavoidable complication arising from liver surgery, profoundly intertwined with its prognosis. The role of lysine methyltransferase SET domain bifurcated 1 (SETDB1) in HIRI remains elusive, despite its confirmation as a potential therapeutic target for diverse diseases. Here, we investigated the mechanism by which SETDB1 regulated HIRI. Methods: RNA sequencing data were used to identify the expression and potential targets of SETDB1 through bioinformatics analysis. To elucidate the impact of SETDB1 on HIRI, both an in vivo model of HIRI in mice and an in vitro model of hepatocyte hypoxia/reoxygenation were established. Biochemical and histological analyses were used to investigate the influence of SETDB1 on liver damage mediated by HIRI. Chromatin immunoprecipitation and coimmunoprecipitation were implemented to explore the in-depth mechanism of SETDB1 regulating HIRI. Results: We confirmed that hepatocellular SETDB1 was up-regulated during HIRI and had a close correlation with HIRI-related inflammation and apoptosis. Moreover, inhibition of SETDB1 could mitigate HIRI-induced liver damage, inflammation, and apoptosis. Through our comprehensive mechanistic investigation, we revealed that SETDB1 interacts with apoptosis-signal-regulating kinase 1 (ASK1) and facilitates the methylation of its lysine residues. Inhibition of SETDB1 resulted in reduced phosphorylation of ASK1, leading to a marked suppression of downstream c-Jun N-terminal kinase (JNK)/p38 signaling pathway activation. The therapeutic effect on inflammation and apoptosis achieved through SETDB1 inhibition was nullified by the restoration of JNK/p38 signaling activation through ASK1 overexpression. Conclusions: The findings from our study indicate that SETDB1 mediates lysine methylation of ASK1 and modulates the activation of the ASK1-JNK/p38 pathway, thus involved in HIRI-induced inflammation and apoptosis. These results suggest that SETDB1 holds promise as a potential therapeutic target for mitigating HIRI.

Ghrelin protects against ischemia/reperfusion-induced hepatic injury via inhibiting Caspase-11-mediated noncanonical pyroptosis

BACKGROUND

Ischemia/reperfusion (I/R) injury is a complication of liver transplantation. I/R-induced inflammatory cell death, namely, pyroptosis, that is triggered by overactive inflammasomes results in the production of proinflammatory cytokines. Hepatic I/R injury correlates with the activation of the Caspase-11-mediated pyroptosis pathway. We investigated whether ghrelin, which is a pleiotropic gut hormone, may have anti-hepatic I/R injury effects, but the mechanism by which Ghrelin ameliorates hepatic I/R -induced injury remains a mystery.

METHODS

Hepatic I/R injury was induced in a mouse model by clamping the left and right lobes of the liver for 90 min followed by reperfusion for 6 h, 12 h, or 24 h. As treatment, a saline with or without ghrelin was infused via the tail vain. Hepatocytes were isolated using a two-step collagenase liver perfusion method.

RESULTS

In our study, treatment with ghrelin protected against hepatic I/R injury as shown by decreased alanine aminotransferase (ALT) and lactate dehydrogenase (LDH) levels (p < 0.001) and reduced the histological injury in liver tissues compared with untreated controls. The LDH level of primary hepatocytes was increased by hypoxia/reoxygenation (H/R), and it was then restored to normal levels by ghrelin-treatment (p < 0.05). Western blotting analysis showed that ghrelin significantly inhibited the expression of pyroptosis-related proteins, including Caspase-11, GSDMD-N, NLRP3 and HMGB1, both in vivo and in vitro (all p < 0.05) compared with the untreated controls. Immunofluorescence showed that the expression of Gasdamin D (GSDMD) in hepatocytes was increased after I/R or H/R, whereas GSDMD expression was reduced by ghrelin treatment (p < 0.05).

CONCLUSIONS

Our findings suggest that ghrelin ameliorated I/R-induced hepatic injury by inhibiting Caspase-11-mediated pyroptosis. Ghrelin may be a potential therapeutic option to prevent hepatic I/R injury after liver transplantation.

FGF18 alleviates hepatic ischemia-reperfusion injury via the USP16-mediated KEAP1/Nrf2 signaling pathway in male mice

Hepatic ischemia-reperfusion injury (IRI) is a common complication occurs during hepatic resection and transplantation. However, the mechanisms underlying hepatic IRI have not been fully elucidated. Here, we aim to explore the role of fibroblast growth factor 18 (FGF18) in hepatic IRI. In this work, we find that Hepatic stellate cells (HSCs) secrete FGF18 and alleviates hepatocytes injury. HSCs-specific FGF18 deletion largely aggravates hepatic IRI. Mechanistically, FGF18 treatment reduces the levels of ubiquitin carboxyl-terminal hydrolase 16 (USP16), leading to increased ubiquitination levels of Kelch Like ECH Associated Protein 1 (KEAP1) and the activation of nuclear factor erythroid 2-related factor 2 (Nrf2). Furthermore, USP16 interacts and deubiquitinates KEAP1. More importantly, Nrf2 directly binds to the promoter of USP16 and forms a negative feedback loop with USP16. Collectively, our results show FGF18 alleviates hepatic IRI by USP16/KEAP1/Nrf2 signaling pathway in male mice, suggesting that FGF18 represents a promising therapeutic approach for hepatic IRI.

Divergent roles of the Hippo pathway in the pathogenesis of idiopathic pulmonary fibrosis: tissue homeostasis and fibrosis

Idiopathic pulmonary fibrosis (IPF) is a progressive aging-related lung disease with a poor prognosis. Despite extensive research, the cause of IPF remains largely unknown and treatment strategies are limited. Proposed mechanisms of the pathogenesis of IPF are a combination of excessive accumulation of the extracellular matrix and dysfunctional lung tissue regeneration. Epithelial cell dysfunction, in addition to fibroblast activation, is considered a key process in the progression of IPF. Epithelial cells normally maintain homeostasis of the lung tissue through regulated proliferation, differentiation, cell death, and cellular senescence. However, various stresses can cause repetitive damage to lung epithelial cells, leading to dysfunctional regeneration and acquisition of profibrotic functions. The Hippo pathway is a central signaling pathway that maintains tissue homeostasis and plays an essential role in fundamental biological processes. Dysregulation of the Hippo pathway has been implicated in various diseases, including IPF. However, the role of the Hippo pathway in the pathogenesis of IPF remains unclear, particularly given the pathway's opposing effects on the 2 key pathogenic mechanisms of IPF: epithelial cell dysfunction and fibroblast activation. A deeper understanding of the relationship between the Hippo pathway and the pathogenesis of IPF will pave the way for novel Hippo-targeted therapies.

METTL3 exacerbates insulin resistance in hepatocytes by regulating m6A modification of cytochrome P450 2B6

BACKGROUND

Insulin resistance (IR) in hepatocytes endangers human health, and frequently results in the development of non-alcoholic fatty liver disease (NAFLD). Research on m6A methylation of RNA molecules has gained popularity in recent years; however, the molecular mechanisms regulating the processes of m6A modification and IR are not known. The cytochrome P450 (CYP450) enzyme system, which is mainly found in the liver, is associated with the pathogenesis of NAFLD. However, few studies have been conducted on CYP450 related m6A methylation. Here, we investigated the role of the methyltransferase METTL3 in exacerbating IR in hepatocytes, mainly focusing on the regulation of m6A modifications in CYP2B6.

METHODS AND RESULTS

Analysis using dot blot and epitranscriptomic chips revealed that the m6A modification pattern of the transcriptome in high-fat diet (HFD)-induced fatty liver and free fatty acid (FFA)-induced fatty hepatocytes showed significant changes. CYP450 family members, especially Cyp2b10, whose homolog in humans is CYP2B6, led to a noticeable increase in m6A levels in HFD-induced mice livers. Application of the METTL3 methyltransferase inhibitor, STM2457, increased the level of insulin sensitivity in hepatocytes. We then analyzed the role of METTL3 in regulating m6A modification of CYP2B6 in hepatocytes. METTL3 regulated the m6A modification of CYP2B6, and a positive correlation was found between the levels of CYP2B6 translation and m6A modifications. Furthermore, interference with METTL3 expression and exposure to STM2457 inhibited METTL3 activity, which in turn interfered with the phosphorylated insulin receptor substrate (pIRS)-glucose transporter 2 (GLUT2) insulin signaling pathway; overexpression of CYP2B6 hindered IRS phosphorylation and translocation of GLUT2 to membranes, which ultimately exacerbated IR.

CONCLUSION

These findings offer unique insights into the role that METTL3-mediated m6A modifications of CYP2B6 play in regulating insulin sensitivity in hepatocytes and provide key information for the development of strategies to induce m6A modifications for the clinical treatment of NAFLD.

PGC-1α inhibits M2 macrophage polarization and alleviates liver fibrosis following hepatic ischemia reperfusion injury

Oxidative stress can induce inflammation, promoting macrophage polarization and liver fibrosis following hepatic ischemia-reperfusion (I/R). Peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) has anti-oxidant and anti-inflammatory activity. However, how PGC-1α regulates macrophage polarization following hepatic I/R remains largely unknown. Male C57BL/6 wild-type mice were pre-treated with vehicle or trichostatin A (TSA) for 2 days and subjected to surgical induction of I/R. Liver injury and fibrosis in individual mice were examined longitudinally and the expression levels of IL-6, STAT3, M2-type macrophage markers, Collagen I and α-SMA in the liver of mice were analyzed by immunohistochemistry, RT-qPCR and Western blot. The potential interaction of PGC-1α with phosphorylated NF-kBp65 was determined by immunoprecipitation. The impacts of PGC-1α deficiency in hepatocytes on their IL-6 production and macrophage polarization were tested in a Transwell co-culture system. Moreover, the M2-type macrophage polarization and liver fibrosis were examined in hepatocyte-specific PGC-1α knockout mice and AAV8-mediated PGC-1α over-expressing mice following liver I/R. The down-regulated PGC-1α expression by I/R was negatively correlated with IL-6 levels in the liver of I/R mice and PGC-1α deficiency enhanced IL-6 expression, STAT3 activation and M2-type macrophage polarization in the I/R mice, which were abrogated by TSA treatment. In addition, PGC-1α directly interacted with phosphorylated NF-kBp65 in I/R livers. Hepatocyte-specific PGC-1α deficiency increased IL-6 production and promoted macrophage polarization toward M2 type when co-culture. More importantly, administration with AAV8-PGC-1α rescued the I/R-induced liver fibrosis by inhibiting the IL-6/JAK2/STAT3 signaling and M2-type macrophage polarization in the liver. These results suggest that PGC-1α may alleviate the I/R-induced liver fibrosis by attenuating the IL-6/JAK2/STAT3 signaling to limit M2-type macrophage polarization. PGC-1α may be a therapeutic target for the treatment of liver fibrosis.

The roles of the Hippo-YAP signalling pathway in Cartilage and Osteoarthritis

Osteoarthritis (OA) is an age-related disease, characterized by cartilage degeneration. The pathogenesis of OA is complicated and the current therapeutic approaches for OA are limited. Cartilage, an integral part of the skeletal system composed of chondrocytes, is essential for skeletal development, tissue patterning, and maintaining the normal activity of joints. The development, homeostasis and degeneration of cartilage are tightly associated with OA. Over the past decade, accumulating evidence indicates that Hippo/YAP is a vital biochemical signalling pathway that strictly governs tissue development and homeostasis. The joint tissues, especially for cartilage, are sensitive to changes of Hippo/YAP signalling. In this review, we summarize the role of Hippo/YAP signalling in cartilage and discuss its involvement in OA progression from points of cartilage degradation, subchondral bone remodeling, and synovial alteration. We also highlight the potential therapeutic implications of Hippo/YAP signalling and further discuss current limitations and controversy on Hippo/YAP-based application for OA treatment.

Liquiritigenin Confers Liver Protection by Enhancing NRF2 Signaling through Both Canonical and Non-canonical Signaling Pathways

Oxidative stress plays a critical role in drug-induced liver injury. In recent years, liquiritigenin (LQ), a natural flavonoid distributed in Glycyrrhizae Radix et Rhizoma (Gan Cao), shows protective effects against oxidative hepatotoxicity. However, the underlying mechanism remains unclear. In this study, we mainly investigated the role of NRF2, a core transcription factor in oxidative stress, in LQ-induced hepatoprotection. Our results indicated that the function of LQ to eliminate reactive oxygen species in liver cells was dependent on NRF2 activation. Both a canonical signaling pathway and a non-canonical signaling pathway are involved in LQ-induced NRF2 activation. LQ induced NRF2 activation in a KEAP1-C151-dependent manner partially. Meanwhile, LQ led to the blockage of autophagic flux and upregulation of p62, which competitively bound with KEAP1 and conferred NRF2 activation in a KEAP1-C151-independent manner. Totally, our study reveals a novel molecular mechanism underlying the hepatoprotection of LQ, providing a new insight into the pathogenesis and therapeutic strategy of oxidative liver injury.

METTL3-mediated m6A mRNA modification was involved in cadmium-induced liver injury

Cadmium is an environmental pollutant that has extensive deleterious effects. However, the mechanisms underlying the hepatotoxicity induced by long-term exposure to cadmium remained undefined. In the present study, we explored the role of m6A methylation in the development of cadmium-induced liver disease. We showed a dynamic change of RNA methylation in liver tissue from mice administrated with cadmium chloride (CdCl2) for 3, 6 and 9 months, respectively. Particularly, the METTL3 expression was declined in a time-dependent manner, associated with the degree of liver injury, indicating the involvement of METTL3 in hepatotoxicity induced by CdCl2. Moreover, we established a mouse model with liver-specific over-expression of Mettl3 and administrated these mice with CdCl2 for 6 months. Notably, METTL3 highly expressed in hepatocytes attenuated CdCl2-induced steatosis and liver fibrosis in mice. In vitro assay also showed METTL3 overexpression ameliorated the CdCl2-induced cytotoxicity and activation of primary hepatic stellate cells. Furthermore, transcriptome analysis identified 268 differentially expressed genes both in mice liver tissue treated with CdCl2 for 3 months and 9 months. Among them, 115 genes were predicted to be regulated by METTL3 determined by m6A2Target database. Further analysis revealed the perturbation of metabolic pathway, glycerophospholipid metabolism, ErbB signaling pathway, Hippo signaling pathway, and choline metabolism in cancer, and circadian rhythm, led to hepatotoxicity induced by CdCl2. Collectively, our findings reveal new insight into the crucial role of epigenetic modifications in hepatic diseases caused by long-term exposure to cadmium.

A Spectrofluorometric Method for Real-Time Graft Assessment and Patient Monitoring

Biomarkers are powerful clinical diagnostics and predictors of patient outcome. However, robust measurements often require time and expensive laboratory equipment, which is insufficient to track rapid changes and limits direct use in the operating room. Here, this study presents a portable spectrophotometric device for continuous real-time measurements of fluorescent and non-fluorescent biomarkers at the point of care. This study measures the mitochondrial damage biomarker flavin mononucleotide (FMN) in 26 extended criteria human liver grafts undergoing hypothermic oxygenated perfusion to guide clinical graft assessment. Real-time data identified seven organs unsuitable for transplant that are discarded. The remaining grafts are transplanted and FMN values correlated with post-transplant indicators of liver function and patient recovery. Further, this study shows how this device can be used to monitor dialysis patients by measuring creatinine in real-time. Our approach provides a simple method to monitor biomarkers directly within biological fluids to improve organ assessment, patient care, and biomarker discovery.

YAP/TAZ: Molecular pathway and disease therapy

The Yes-associated protein and its transcriptional coactivator with PDZ-binding motif (YAP/TAZ) are two homologous transcriptional coactivators that lie at the center of a key regulatory network of Hippo, Wnt, GPCR, estrogen, mechanical, and metabolism signaling. YAP/TAZ influences the expressions of downstream genes and proteins as well as enzyme activity in metabolic cycles, cell proliferation, inflammatory factor expression, and the transdifferentiation of fibroblasts into myofibroblasts. YAP/TAZ can also be regulated through epigenetic regulation and posttranslational modifications. Consequently, the regulatory function of these mechanisms implicates YAP/TAZ in the pathogenesis of metabolism-related diseases, atherosclerosis, fibrosis, and the delicate equilibrium between cancer progression and organ regeneration. As such, there arises a pressing need for thorough investigation of YAP/TAZ in clinical settings. In this paper, we aim to elucidate the signaling pathways that regulate YAP/TAZ and explore the mechanisms of YAP/TAZ-induce diseases and their potential therapeutic interventions. Furthermore, we summarize the current clinical studies investigating treatments targeting YAP/TAZ. We also address the limitations of existing research on YAP/TAZ and propose future directions for research. In conclusion, this review aims to provide fresh insights into the signaling mediated by YAP/TAZ and identify potential therapeutic targets to present innovative solutions to overcome the challenges associated with YAP/TAZ.

Promising small molecule anti-fibrotic agents: Newly developed or repositioned drugs targeting myofibroblast transdifferentiation

Fibrosis occurs in all organs and tissues except the brain, and its progression leads to dysfunction of affected organs. Fibrosis-induced organ dysfunction results from the loss of elasticity, strength, and functionality of tissues due to the extracellular matrix secreted by myofibroblasts that express smooth muscle-type actin as a marker. Myofibroblasts, which play a major role in fibrosis, were once thought to originate exclusively from activated fibroblasts; however, it is now clear that myofibroblasts are diverse in origin, from epithelial cells, endothelial cells, adipocytes, macrophages, and other cells. Fibrosis of vital organs, such as the heart, lungs, kidneys, and liver, is a serious chronic disease that ultimately leads to death. Currently, anti-cancer drugs have made remarkable progress, as evidenced by the development of many molecular-targeted drugs, and are making a significant contribution to improving the prognosis of cancer treatment. However, the development of anti-fibrotic agents, which also play an important role in prognosis, has lagged. In this review, the current knowledge regarding myofibroblasts is summarized, with particular attention given to their origin and transdifferentiation signaling pathways (e.g., TGF-β, Wnt/β-catenin, YAP/TAZ and AMPK signaling pathways). The development of new small molecule anti-fibrotic agents and the repositioning of existing drugs targeting myofibroblast transdifferentiation are discussed.

Advances in Understanding the Role of NRF2 in Liver Pathophysiology and Its Relationship with Hepatic-Specific Cyclooxygenase-2 Expression

Oxidative stress and inflammation play an important role in the pathophysiological changes of liver diseases. Nuclear factor erythroid 2-related factor 2 (NRF2) is a transcription factor that positively regulates the basal and inducible expression of a large battery of cytoprotective genes, thus playing a key role in protecting against oxidative damage. Cyclooxygenase-2 (COX-2) is a key enzyme in prostaglandin biosynthesis. Its expression has always been associated with the induction of inflammation, but we have shown that, in addition to possessing other benefits, the constitutive expression of COX-2 in hepatocytes is beneficial in reducing inflammation and oxidative stress in multiple liver diseases. In this review, we summarized the role of NRF2 as a main agent in the resolution of oxidative stress, the crucial role of NRF2 signaling pathways during the development of chronic liver diseases, and, finally we related its action to that of COX-2, where it appears to operate as its partner in providing a hepatoprotective effect.

Hepatocyte HSPA12A inhibits macrophage chemotaxis and activation to attenuate liver ischemia/reperfusion injury via suppressing glycolysis-mediated HMGB1 lactylation and secretion of hepatocytes

Rationale: Liver ischemia-reperfusion (LI/R) injury is characterized by two interconnected phases: local ischemia that causes hepatic cell damage to release damage-associated molecular pattern (DAMPs), and DAMPs that recruit immune cells to elicit inflammatory cascade for further injury of hepatocytes. High-mobility group box 1 (HMGB1) is a representative DAMP. Studies in macrophages demonstrated that HMGB1 is secreted after lactylation during sepsis. However, whether lactylation mediates HMGB1 secretion from hepatocytes after LI/R is known. Heat shock protein A12A (HSPA12A) is an atypical member of HSP70 family. Methods: Gene expression was examined by microarray analysis and immunoblotting. The hepatic injury was analyzed using released ALT and AST activities assays. Hepatic macrophage chemotaxis was evaluated by Transwell chemotaxis assays. Inflammatory mediators were evaluated by immunoblotting. HMGB1 secretion was examined in exosomes or serum. HMGB1 lactylation was determined using immunoprecipitation and immunoblotting. Results: Here, we report that LI/R decreased HSPA12A expression in hepatocytes, while hepatocyte-specific HSPA12A overexpression attenuated LI/R-induced hepatic dysfunction and mortality of mice. We also noticed that hepatocyte HSPA12A overexpression suppressed macrophage chemotaxis to LI/R-exposed livers in vivo and to hypoxia/reoxygenation (H/R)-exposed hepatocytes in vitro. The LI/R-increased serum HMGB1 levels of mice and the H/R-increased HMGB1 lactylation and secretion levels of hepatocytes were also inhibited by hepatocyte HSPA12A overexpression. By contrast, HSPA12A knockout in hepatocytes promoted not only H/R-induced HMGB1 lactylation and secretion of hepatocytes but also the effects of H/R-hepatocytes on macrophage chemotaxis and inflammatory activation, while all these deleterious effects of HSPA12A knockout were reversed following hepatocyte HMGB1 knockdown. Further molecular analyses showed that HSPA12A overexpression reduced glycolysis-generated lactate, thus decreasing HMGB1 lactylation and secretion from hepatocytes, thereby inhibiting not only macrophage chemotaxis but also the subsequent inflammatory cascade, which ultimately protecting against LI/R injury. Conclusion: Taken together, these findings suggest that hepatocyte HSPA12A is a novel regulator that protects livers from LI/R injury by suppressing glycolysis-mediated HMGB1 lactylation and secretion from hepatocytes to inhibit macrophage chemotaxis and inflammatory activation. Therefore, targeting hepatocyte HSPA12A may have therapeutic potential in the management of LI/R injury in patients.

Knockdown of Yap attenuates TAA-induced hepatic fibrosis by interaction with hedgehog signals

Liver fibrosis is an aberrant wound healing response to tissue injury characterized by excessive extracellular matrix deposition and loss of normal liver architecture. Hepatic stellate cells (HSCs) activation is regards to be the major process in liver fibrogenesis which is dynamic and reversible. Both Hippo signaling core factor Yap and Hedgehog (Hh) signaling promote HSCs transdifferentiation thereby regulating the repair process of liver injury. However, the molecular function of YAP and the regulation between Yap and Hh during fibrogenesis remain uncertain. In this study, the essential roles of Yap in liver fibrosis were investigated. Yap was detected to be increased in liver fibrotic tissue by the thioacetamide (TAA)-induced zebrafish embryonic and adult models. Inhibition of Yap by both embryonic morpholino interference and adult's inhibitor treatment was proved to alleviate TAA-induced liver lesions by and histology and gene expression examination. Transcriptomic analysis and gene expression detection showed that Yap and Hh signaling pathway have a cross talking upon TAA-induced liver fibrosis. In addition, TAA induction promoted the nuclear colocalization of YAP and Hh signaling factor GLI2α. This study demonstrates that Yap and Hh play synergistic protective roles in liver fibrotic response and provides new theoretical insight concerning the mechanisms of fibrosis progression.

TRPM2 Mediates Hepatic Ischemia-Reperfusion Injury via Ca2+-Induced Mitochondrial Lipid Peroxidation through Increasing ALOX12 Expression

Hepatic ischemia-reperfusion (IR) injury is a serious clinical problem that complicates liver resection and transplantation. Despite recent advances in understanding of the pathophysiology of hepatic IR injury, effective interventions and therapeutics are still lacking. Here, we examined the role of transient receptor potential melastatin 2 (TRPM2), a Ca²⁺-permeable, non-selective cation channel, in mediating hepatic IR injury. Our data showed that TRPM2 deficiency attenuated IR-induced liver dysfunction, inflammation, and cell death in mice. Moreover, RNA sequencing analysis indicated that TRPM2-induced IR injury occurs via ferroptosis-related pathways. Consistently, as a ferroptosis inducer, (1S,3R)-RSL3 treatment induced mitochondrial dysfunction in hepatocytes and a TRPM2 inhibitor suppressed this. Interestingly, TRPM2-mediated calcium influx caused mitochondrial calcium accumulation via the mitochondrial Ca²⁺-selective uniporter and increased the expression level of arachidonate 12-lipoxygenase (ALOX12), which results in mitochondrial lipid peroxidation during hepatic IR injury. Furthermore, hepatic IR injury-induced ferroptosis was obviously relieved by a TRPM2 inhibitor or calcium depletion, both in vitro and in vivo. Collectively, these findings demonstrate a crucial role for TRPM2-mediated ferroptosis in hepatic IR injury via increased Ca²⁺-induced ALOX12 expression, indicating that pharmacological inhibition of TRPM2 may provide an effective therapeutic strategy for hepatic IR injury-related diseases, such as during liver resection and transplantation.