Endothelial POFUT1 controls injury-induced liver fibrosis by repressing fibrinogen synthesis

Liver sinusoidal endothelial cells in hepatic fibrosis: opportunities for future strategies

Liver sinusoidal endothelial cells (LSECs) are highly specialized endothelial cells that form the interface between the hepatic vasculature and parenchymal cells, playing a crucial role in maintaining hepatic homeostasis. Under pathological conditions, LSECs undergo capillarization, marked by the loss of fenestrae and formation of a basement membrane, thereby impairing microcirculation and promoting fibrosis. Beyond capillarization, LSECs experience a spectrum of pathological changes-including angiogenesis, endothelial-to-mesenchymal transition (EndMT), autophagy, and senescence-all of which contribute to fibrogenesis through distinct molecular pathways. Moreover, LSECs orchestrate liver fibrotic remodeling through dynamic crosstalk with hepatic stellate cells (HSCs), hepatocytes, Kupffer cells, and immune cells, exerting both pro- and anti-fibrotic effects. This review comprehensively summarizes LSECs dysfunction in hepatic fibrosis, with a particular focus on intercellular communication and emerging therapeutic strategies. Elucidating the regulatory networks that govern LSECs behavior may uncover new opportunities for the diagnosis and treatment of chronic liver disease.

Bioinformatics-Guided Experimental Validation Identifies NQO1 as a Senescence-Ferroptosis Hub in Liver Fibrosis

Background: As a pivotal point for the development of liver diseases, liver fibrosis (LF) is closely associated with cellular senescence and ferroptosis. However, there is a lack of effective markers that accurately predict LF status. This study aims to identify key genes involved in LF through bioinformatics analysis and experimental validation. Methods: We used bioinformatics analysis of Gene Expression Omnibus (GEO) data to investigate the gene functions, prognostic value, and immune associations of characteristic genes in LF. Functional enrichment analysis of DEGs was performed using GO and KEGG. Immune cell types and their proportions were estimated with CIBERSORTx. In addition, we analyzed the role of NQO1 in LF using IHC, WB, PCR, and flow cytometry. Results: Bioinformatics analysis identified 10 hub genes, including AR, CDKN1A, GJA1, CTSB, HIF1A, HMGB1, NQO1, PARP1, PTEN, and TXN. Among them, NQO1 was strongly correlated with immune cell activity. Experimental validation confirmed that NQO1 is upregulated and promotes αSMA and COL1A1 expression in hepatic stellate cells (HSCs). Knockdown of NQO1 significantly affected the proliferation of HSCs. Conclusions: NQO1 plays a critical role in HSC senescence and ferroptosis, promoting HSC activation and contributing to LF progression. Our findings suggest that NQO1 may serve as a potential biomarker for LF.

NSun2-Mediated tsRNAs Alleviate Liver Fibrosis via FAK Dephosphorylation

Sinusoidal capillarization - key symptoms of liver fibrosis progression - represents potential therapeutic targets. tRNA modification-mediated tRNA-derived small RNAs (tsRNAs) play a role in angiogenesis. NSun2, an RNA methyltransferase, generates a significant number of tsRNAs. However, the role of NSun2 and its mediated tsRNAs in liver fibrosis remains unclear. In this study, NSun2 deficiency was found to inhibit sinusoidal capillarization, alleviating liver fibrosis. Furthermore, endothelial cell angiogenesis and migration were disrupted in NSun2 knockout mice. Mechanistically, reduced NSun2 expression led to alterations in the functional tsRNAs tRF-1-S25 and tRF-5-V31, which regulate sinusoidal capillarization by targeting key proteins, including DUSP1 and FAK - crucial clinical targets. Moreover, intravenous injection of tRF-1-S25 and tRF-5-V31 inhibitor rescued liver fibrosis in mice. In conclusion, tsRNAs generated by NSun2-mediated modification of tRNAs inhibit sinusoidal capillarization. Furthermore, targeting the DUSP1/FAK/p-FAK pathway offers an innovative approach to treat this disease.

AI-based phenotyping of hepatic fiber morphology to inform molecular alterations in metabolic dysfunction-associated steatotic liver disease

BACKGROUND AND AIMS

Hepatic fiber morphology may significantly enhance our understanding of molecular alterations in metabolic dysfunction-associated steatotic liver disease (MASLD). We aimed to comprehensively characterize hepatic fiber morphological phenotypes in MASLD and their associated molecular alterations using multilayer omics analyses.

APPROACH AND RESULTS

To quantify the morphological phenotypes of hepatic fibers, the artificial intelligence-based FibroNest algorithm (PharmaNest) was applied to 94 MASLD-affected liver biopsies, among which 12 (13%) had concurrent HCC. FibroNest identified 327 fiber phenotypes that were summarized into 8 major principal components, named FibroPC1-8. Next, molecular alterations captured by morphological fiber phenotypes were evaluated by comparison with genome-wide transcriptomics of paired liver samples. Pathway analyses revealed that FibroPCs more sensitively captured MASLD-related molecular alterations, such as upregulation of interleukin-6 and susceptibility to resmetirom, compared with the histological fibrosis stage. Among them, FibroPC4, which reflects reticular fibers, was associated with a gene signature predictive of incident HCC from MASLD. Furthermore, we used a spatial single-cell transcriptome, CosMx, to reveal the cell-cell interactions driving MASLD pathogenesis, as captured by FibroPC4. CosMx revealed that the FibroPC4-rich microenvironment contains HCC-promoting HSCs located adjacent to periportal endothelial cells. Neighboring cell analyses suggested that the HCC-promoting phenotype of HSCs was acquired by insulin growth factor-binding protein 7 secreted from senescent periportal endothelial cells. Consistently, in vitro experiments showed that insulin growth factor-binding protein 7 transformed HSCs into an HCC-promoting phenotype.

CONCLUSIONS

Hepatic morphological fiber phenotyping can reveal the disease progression and underlying mechanisms of MASLD.

IRG1/Itaconate inhibits hepatic stellate cells ferroptosis and attenuates TAA-induced liver fibrosis by regulating SLC39A14 expression

This study aimed to elucidate the protective roles of Immune Response Gene-1 (IRG1) and exogenous itaconate in murine models of hepatic fibrosis and to delineate the underlying mechanistic pathways using both wild-type and IRG1-deficient (IRG1-/-) mice. Primary murine stellate cells (mHSC) and bone marrow-derived macrophages (BMDM) were isolated and cocultured. Hepatocellular fibrosis was induced in vitro using Transforming Growth Factor-beta (TGF-β) to evaluate the protective efficacy of IRG1/itaconate. Histopathological damage in the hepatic tissues was assessed using Hematoxylin and Eosin (H&E), Masson's trichrome, and Sirius red staining, followed by hepatic fibrosis scoring. The levels of released inflammatory cytokines were quantified using enzyme-linked immunosorbent assay (ELISA) kits. Immunohistochemistry was used to detect 4-Hydroxynonenal (4-HNE) levels and Perls staining was used to assess ferroptosis. RNA sequencing and gene enrichment analyses were performed to identify implicated molecular entities and signaling pathways. IRG1 and SLC39A14 knockdown and overexpression cell lines were generated. Quantitative real-time PCR (qRT-PCR) and western blotting (WB) were used to measure the mRNA and protein expression levels in hepatic tissues and cells. Kits were used to assess reactive oxygen species (ROS) and malondialdehyde (MDA) levels, and the concentrations of liver enzymes, iron, GSH, and GSSG within hepatic tissues and cells.4-octyl itaconate (4-OI) significantly attenuated the histopathological damage in hepatic tissues, preserved the normal hepatic function, effectively reduced the release of inflammatory cytokines, and mitigated oxidative stress markers such as ROS and MDA in Thioacetamide (TAA)-induced fibrotic mice. Notably, this study is the first to reveal the pivotal role of SLC39A14 in the pathogenesis of hepatic fibrosis in murine models and elucidate how IRG1/itaconate mediates downstream ferroptosis-related signaling pathways by targeting SLC39A14, thereby inhibiting ferroptosis-induced hepatic fibrosis. IRG1/itaconate can alleviate the TAA-induced hepatic fibrosis in mice by regulating the expression of SLC39A14, consequently suppressing hepatic stellate cell ferroptosis.

IL-1β-induced pericyte dysfunction with a secretory phenotype exacerbates retinal microenvironment inflammation via Hes1/STAT3 signaling pathway

Retinal pericytes are mural cells surrounding capillaries to maintain the integrity of blood-retina barrier and regulate vascular behaviors. Pericyte loss has been considered as the hallmark of diabetic retinopathy (DR), which is a major complication of diabetes and the leading cause of blindness in adults. However, the precise function of pericytes in regulating the retinal microenvironment and the underlying mechanism remains largely unknown. In this study, we observed a secretory phenotype of pericytes with elevated inflammatory cytokines in response to Interleukin-1β (IL-1β), a canonical inflammatory cytokine which significantly increases during the initial stages of diabetic retinopathy. This phenotype is also accompanied by reduced expression of adherent junction proteins and contractile proteins. Paracrine cytokines derived from pericytes further induce the chemotaxis of microglia cells and trigger detrimental changes in endothelial cells, including reduced expression of tight junction protein Occludin and increased apoptosis. Mechanically, the secretion potential in pericytes is partially mediated by Hes1/STAT3 signaling pathway. Moreover, co-injection of stattic, an inhibitor targeting STAT3 activation, could effectively attenuate IL-1β-induced retinal inflammation and microglial activation in retina tissues. Collectively, these findings demonstrate the potential of retinal pericytes as an initial inflammatory sensor prior to their anatomical pathological loss, via undergoing phenotypic changes and secreting paracrine factors to amplify local inflammation and damage endothelial cells in vitro. Furthermore, inhibition of STAT3 activation by inhibitors significantly ameliorates IL-1β-induced retinal inflammation, suggesting STAT3 in retinal pericytes as a promising target for alleviating DR and other IL-1β-induced ocular diseases.

Ginsenoside compound K restrains hepatic fibrotic response by dual-inhibition of GLS1 and LDHA

BACKGROUND

Liver fibrosis is a dynamic process marked by the accumulation of extracellular matrix due to hepatic stellate cells (HSCs) activation. Ginsenoside compound K (CK), a rare derivative of its parent ginsenosides, is known to significantly ameliorate metabolic disorders.

PURPOSE

The aim of this study was to elucidate the protective effects of CK against liver fibrosis with a focus on metabolic regulation.

METHODS

We established liver fibrosis models in mice using carbon tetrachloride (CCl4) challenge, bile duct ligation, or a methionine-choline deficient diet, with continuous oral administration of CK at specified doses and intervals. Simultaneously, we examined the impact of CK on metabolic regulation in cultured HSCs and investigated the associated mechanisms.

RESULTS

CK was found to alleviate liver injury and curb fibrotic responses in mouse models, as well as decrease elevated levels of liver enzyme. Metabolomic analysis in vitro highlighted the crucial roles of pyruvate and glutamine metabolism in metabolic remodeling. Immunohistochemical staining indicated significantly elevated expressions of lactate dehydrogenase A (LDHA) (p = 0.014) and glutaminase 1 (GLS1) (p = 0.024) in liver cirrhosis patients. Comparable alterations were noted in the liver of model mice and in cultured HSCs. Molecular docking and bio-layer interferometry demonstrated that CK interacts with and inhibits the activities of LDHA and GLS1. As expected, CK attenuated glycolysis and glutaminolysis, reducing HSC growth dependently on lactate and α-ketoglutarate (α-KG). Upon HSC activation, metabolism is reprogrammed with Myc as a key regulator, transcriptionally controlling LDHA, GLS1, and glutamine transporters SLC1A5 and SLC38A5. CK inhibited Myc induction, integrating glycolysis and glutaminolysis regulation to counteract the fibrotic response.

CONCLUSION

CK inhibited LDHA and GLS1 activities, thereby inhibiting hepatic fibrosis. These findings offer new insights into the role of ginsenosides in liver protection, especially regarding metabolic disorders.