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This study presents the development and validation of an innovative microfluidic liver-on-a-chip device utilizing gravity-driven perfusion for the evaluation of drug hepatotoxicity. This research involved the construction of a hydrogel-based coculture chip that integrates liver parenchymal and stellate cells within a tri-channel configuration. The assembly and operation of the liver-on-a-chip and its accompanying custom rocker were straightforward. The cells in the chip maintained high viability and continuously synthesized liver albumin over extended culture durations. Acetaminophen (APAP), a hepatic injury-inducing drug, was utilized as a positive control in hepatic toxicity assays on the chip. The liver chip exhibited hepatotoxic responses comparable to those observed in 2D models. Furthermore, in this study we evaluated the effects of two plant-derived natural compounds, aristolochic acid I (AA) and its analog aristolactam AII (AL), in both 2D cell models and the liver-on-a-chip system. AA, known for its hepatorenal toxicity, was observed to cause hepatotoxicity in both the 2D models and on the chip. The flow cytometry and mRNA sequencing results confirmed the propensity of these compounds to induce liver cell apoptosis. Notably, AL, previously considered nontoxic, provoked a significant decrease in the hepatic functionality marker albumin exclusively in the liver chip but not in 2D models, indicating the liver chip's enhanced sensitivity to toxic substances. In summary, this pumpless liver-on-a-chip is a simple yet powerful tool for drug hepatotoxicity studies. [ABSTRACT FROM AUTHOR]

Metabolic dysfunction-associated steatohepatitis (MASH), formerly known as nonalcoholic steatohepatitis (MASH), is a major risk factor for cirrhosis and hepatocellular carcinoma (HCC) and a leading cause of liver transplantation. MASH is caused by an accumulation of toxic fat molecules in the hepatocyte which leads to inflammation and fibrosis. Inadequate human "MASH in a dish" models have limited our advances in understanding MASH pathogenesis and in drug discovery. This study uses complex multicellular 3D bioprinting, combining hepatocytes with nonparenchymal cells in physiologically relevant cell ratios using biocompatible hydrogels to generate bioinks Bioprinted human liver tissues consisting of the four major cell types, (hepatocytes, liver endothelial cells, Kupffer cells, and hepatic stellate cells) are generated from cells purified from normal human livers, using this complex bioprinting platform. These liver tissues are incubated in a cocktail consisting of fatty acids, lipopolysaccharide (LPS), and fructose to produce a MASH phenotype in comparison to liver tissues incubated in control media. Furthermore, these bioprinted liver tissues are of sufficient size to undergo histological processing and immunohistchemistry comparable to classic clinical pathological analysis. The MASH liver tissues develop hepatocyte steatosis, inflammation, and fibrosis, in response to the MASH induction media. Additionally, the transcriptome of the MASH tissues differed significantly from the healthy tissues and more closely resembled the transcriptome of biopsies of MASH livers from patients Thus, this study has developed a MASH bioprinted liver tissue suitable for studies on pathophysiology and drug discovery. [ABSTRACT FROM AUTHOR]

Cell states are modulated by intrinsic driving forces such as gene expression noise and extrinsic signals from the tissue microenvironment. The distinction between intrinsic and extrinsic cell state determinants is essential for understanding the regulation of cell fate in tissues during development, homeostasis and disease. The rapidly growing availability of single-cell resolution spatial transcriptomics makes it possible to meet this challenge. However, available computational methods to infer topological tissue domains, spatially variable genes, or ligand-receptor interactions are limited in their capacity to capture cell state changes driven by crosstalk between individual cell types within the same niche. We present NiCo, a computational framework for integrating single-cell resolution spatial transcriptomics with matched single-cell RNA-sequencing reference data to infer the influence of the spatial niche on the cell state. By applying NiCo to mouse embryogenesis, adult small intestine and liver data, we demonstrate the ability to predict novel niche interactions that govern cell state variation underlying tissue development and homeostasis. In particular, NiCo predicts a feedback mechanism between Kupffer cells and neighboring stellate cells dampening stellate cell activation in the normal liver. NiCo provides a powerful tool to elucidate tissue architecture and to identify drivers of cellular states in local niches. A key question in single-cell biology is how cells communicate and exchange information with neighboring cells in tissues. Here, the authors introduce NiCo to predict the downstream effect of cell-cell interactions on cellular states in tissue niches from spatial transcriptomics data. [ABSTRACT FROM AUTHOR]

Macrophages are pleiotropic and diverse cells that populate all tissues of the body. Besides tissue-specific resident macrophages such as alveolar macrophages, Kupffer cells, and microglia, multiple organs harbor at least two subtypes of other resident macrophages at steady state. During certain circumstances, like tissue insult, additional subtypes of macrophages are recruited to the tissue from the monocyte pool. Previously, a recruited macrophage population marked by expression of Spp1, Cd9, Gpnmb, Fabp5, and Trem2, has been described in several models of organ injury and cancer, and has been linked to fibrosis in mice and humans. Here, we show that Notch2 blockade, given systemically or locally, leads to an increase in this putative pro-fibrotic macrophage in the lung and that this macrophage state can only be adopted by monocytically derived cells and not resident alveolar macrophages. Using a bleomycin and COVID-19 model of lung injury and fibrosis, we find that the expansion of these macrophages before lung injury does not promote fibrosis but rather appears to ameliorate it. This suggests that these damage-associated macrophages are not, by themselves, drivers of fibrosis in the lung. Macrophages are pleiotropic and can have different functions and phenotypes. Here the authors show that a population of macrophages, previously described as pro-fibrotic, can be induced through Notch2 blockade and that in a mouse lung injury and fibrosis model this macrophage population does not promote inflammation or fibrosis. [ABSTRACT FROM AUTHOR]

In adults, liver-resident macrophages, or Kupffer cells (KCs), reside in the sinusoids and sterilize circulating blood by capturing rapidly flowing microbes. We developed quantitative intravital imaging of 1-day-old mice combined with transcriptomics, genetic manipulation, and in vivo infection assays to interrogate increased susceptibility of newborns to bloodstream infections. Whereas 1-day-old KCs were better at catching Escherichia coli in vitro, we uncovered a critical 1-week window postpartum when KCs have limited access to blood and must translocate from liver parenchyma into the sinusoids. KC migration was independent of the microbiome but depended on macrophage migration inhibitory factor, its receptor CD74, and the adhesion molecule CD44. On the basis of our findings, we propose a model of progenitor macrophage seeding of the liver sinusoids via a reverse transmigration process from liver parenchyma. These results also illustrate the importance of developing newborn mouse models to understand newborn immunity and disease. Editor's summary: Newborns are particularly vulnerable to bloodstream bacterial infections that can lead to meningitis, but the mechanisms underlying this susceptibility are not fully understood. Using real-time intravital microscopy of neonatal mice, Araujo David et al. found that relocalization of Kupffer cells (KCs) from the liver parenchyma into sinusoids during the first week of life coincides with improved clearance of bloodstream bacteria. KC migration into liver sinusoids required macrophage migration inhibitory factor and its receptor CD74 but was independent of the microbiome. These findings demonstrate that delayed KC seeding of the liver sinusoids postnatally may underlie the increased susceptibility to bloodstream infections in newborns. —Claire Olingy [ABSTRACT FROM AUTHOR]

Septic patients, coupling severe disseminated intravascular coagulation (DIC) and thrombocytopenia, have poor prognoses and higher mortality. The platelet glycoprotein Ibα (GPIbα) is involved in thrombosis, hemostasis, and inflammation response. However, it remains unclear whether the GPIbα cytoplasmic tail regulates sepsis-mediated platelet activation and inflammation, especially in Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) infections. Using a mouse model of S. aureus-induced bacteremia, we found that both 10 amino acids of GPIbα C-terminal sequence deficiency and pharmacologic inhibition of protein kinase C (PKC) alleviated pathogenesis by diminishing platelet activation and aggregate formation. Furthermore, the GPIbα cytoplasmic tail promoted the phagocytosis of platelets by Kupffer cells in vivo. The genetically deficient GPIbα cytoplasmic tail also downregulated inflammatory cytokines and reduced liver damage, ultimately improving the survival rate of the septic mice. Our results illustrate that the platelet GPIbα cytoplasmic domain exacerbates excessive platelet activation and inflammation associated with sepsis through a PKC-dependent pathway. Thus, our findings provide insights for the development of effective therapeutic strategies using PKC inhibitor treatment against bacterial infection. [ABSTRACT FROM AUTHOR]

Analyzing tissue microstructure is essential for understanding complex biological systems in different species. Tissue functions largely depend on their intrinsic tissue architecture. Therefore, studying the three-dimensional (3D) microstructure of tissues, such as the liver, is particularly fascinating due to its conserved essential roles in metabolic processes and detoxification. Here, we present TiMiGNet, a novel deep learning approach for virtual 3D tissue microstructure reconstruction using Generative Adversarial Networks and fluorescence microscopy. TiMiGNet overcomes challenges such as poor antibody penetration and time-intensive procedures by generating accurate, high-resolution predictions of tissue components across large volumes without the need of paired images as input. We applied TiMiGNet to analyze tissue microstructure in mouse and human liver tissue. TiMiGNet shows high performance in predicting structures like bile canaliculi, sinusoids, and Kupffer cell shapes from actin meshwork images. Remarkably, using TiMiGNet we were able to computationally reconstruct tissue structures that cannot be directly imaged due experimental limitations in deep dense tissues, a significant advancement in deep tissue imaging. Our open-source virtual prediction tool facilitates accessible and efficient multi-species tissue microstructure analysis, accommodating researchers with varying expertise levels. Overall, our method represents a powerful approach for studying tissue microstructure, with far-reaching applications in diverse biological contexts and species. [ABSTRACT FROM AUTHOR]

Resident macrophages of various mammalian organs are characterized by several distinctive features in their gene expression profile and phenotype, including involvement in the regulation of organ functions, as well as reduced sensitivity to proinflammatory activation factors. The reasons for the formation of such a specific phenotype remain the subject of intensive research. Some papers emphasize the role of the origin of organ macrophages. Other studies indicate that monocytes that develop in the red bone marrow are also able to form resident macrophages with a phenotype characteristic of a particular organ, but this requires appropriate microenvironmental conditions. In this article, we studied the possibility of differentiation of monocyte‐derived macrophages into cells with a Kupffer‐like phenotype under the influence of the main stromal components of Kupffer cells macrophage niche: Ito cells, liver sinusoid endotheliocytes and hepatocyte growth factor (HGF). It was found that Kupffer cells are characterized by several features, including increased expression of transcription factors Spic and Id3, as well as MUP family genes, Clusterin and Ngp genes. In addition, Kupffer cells were characterized by a higher proliferative activity. The expression of marker genes of Kupffer cells (i.e. Id3, Spic, Marco and Timd4) increased in monocyte‐derived macrophages during coculture with Ito cells, liver sinusoid endothelial cells, macrophage colony–stimulating factor and HGF cells only by 3 days. However, the expression level of these genes was always higher in Kupffer cells. In addition, a complete coincidence of the expressed gene profile in monocyte‐derived macrophages and Kupffer cells did not occur even after 3 days of culturing. [ABSTRACT FROM AUTHOR]

Trichloroethylene (TCE) is a volatile, colorless liquid that is widely used as a chlorinated organic vehicle in industrial production and processing industries. Many workers exposed to trichloroethylene may develop trichloroethylene hypersensitivity syndrome (THS). However, the underlying mechanism of THS is still unclear, especially liver injury. The present study aimed to investigate whether Wnt5a/c-Jun N-terminal kinase (JNK) is involved in and regulates liver injury caused by TCE exposure and to provide new directions for the prevention and treatment in clinical settings of liver injury caused by TCE exposure. We used 6- to 8-week-old SPF-grade BALB/c female mice to establish a TCE sensitization model and explored the mechanism through inhibitor intervention. We found that the expression of Wnt5a/JNK was significantly elevated in the liver of TCE sensitization-positive mice. Inhibitors of Wnt Production 2 (IWP-2) are known antagonists of the Wnt pathway. TCE-sensitization mice treated with IWP-2 showed downregulated Wnt5a/JNK expression, reduced Kupffer cell activation, and decreased liver injury. At the same time, we found that phosphorylated JNK in TCE-sensitization mouse livers and extracted Kupffer cells showed a significant downward trend after inhibition of Wnt5a function. We also found that a specific JNK inhibitor, SP600125, decreased the secretion of cytokines and chemokines and decreased Kupffer cell activation. We demonstrated that Wnt5a/JNK was involved in the regulation of liver injury in TCE-sensitization mice and that it exacerbated liver injury by activating Kupffer cells and releasing chemokines. We therefore hypothesized that Kupffer cell activation was affected by JNK, which reduced chemokine and cytokine secretion and attenuated liver injury in TCE-sensitization mice. [ABSTRACT FROM AUTHOR]

Inflammatory signals lead to recruitment of circulating monocytes and induce their differentiation into pro-inflammatory macrophages. Therefore, whether blocking inflammatory monocytes can mitigate disease progression is being actively evaluated. Here, we employ multiple lineage-tracing models and show that monocyte-derived macrophages (mo-mac) are the major population of immunosuppressive, liver metastasis-associated macrophages (LMAM), while the proportion of Kupffer cells (KC) as liver-resident macrophages is diminished in metastatic nodules. Paradoxically, genetic ablation of mo-macs results in only a marginal decrease in LMAMs. Using a proliferation-recording system and a KC-tracing model in a monocyte-deficient background, we find that LMAMs can be replenished either via increased local macrophage proliferation or by promoting KC infiltration. In the latter regard, KCs undergo transient proliferation and exhibit substantial phenotypic and functional alterations through epigenetic reprogramming following the vacating of macrophage niches by monocyte depletion. Our data thus suggest that a simultaneous blockade of monocyte recruitment and macrophage proliferation may effectively target immunosuppressive myelopoiesis and reprogram the microenvironment towards an immunostimulatory state. In liver metastasis of cancer, the inflammatory macrophage niche is dominated by both circulating monocytes and local expansion, but the nature and dynamic of this niche is still unclear. Here the authors use mouse genetic models and lineage-tracing tools to show that, under the condition of monocyte depletion, Kupffer cells pursue epigenetic reprogramming to contribute to this niche. [ABSTRACT FROM AUTHOR]

Primary biliary cholangitis (PBC) is a chronic autoimmune liver disease characterized by multilineage immune dysregulation, which subsequently causes inflammation, fibrosis, and even cirrhosis of liver. Due to the limitation of traditional assays, the local hepatic immunopathogenesis of PBC has not been fully characterized. Here, we utilize single-cell RNA sequencing technology to depict the immune cell landscape and decipher the molecular mechanisms of PBC patients. We reveal that cholangiocytes and hepatic stellate cells are involved in liver inflammation and fibrosis. Moreover, Kupffer cells show increased levels of inflammatory factors and decreased scavenger function related genes, while T cells exhibit enhanced levels of inflammatory factors and reduced cytotoxicity related genes. Interestingly, we identify a liver-resident Th1-like population with JAK-STAT activation in the livers of both PBC patients and murine PBC model. Finally, blocking the JAK-STAT pathway alleviates the liver inflammation and eliminates the liver-resident Th1-like cells in the murine PBC model. In conclusion, our comprehensive single-cell transcriptome profiling expands the understanding of pathological mechanisms of PBC and provides potential targets for the treatment of PBC in patients. Primary biliary cholangitis is a chronic autoimmune disease critically linked to immunological dysregulation but the local immune-pathogenesis is poorly understood. Here the authors present single cell transcriptomic characterisation of primary biliary cholangitis and implicates Th1 like cells in a murine model. [ABSTRACT FROM AUTHOR]

Listeria monocytogenes (LM) possesses the ability to breach multiple barriers and elicit intricate immune responses. However, there remains a lack of explicit understanding regarding how LM evades innate immune surveillance within the body. Here, we utilized liver intravital imaging to elucidate the dynamic process of LM during infection in the liver. We discovered that LM can rapidly escape from Kupffer cells (KCs) through listeriolysin O (LLO) and proliferate within hepatocytes. Upon LM exposure to the hepatic sinusoids, neutrophils rapidly aggregate at the site of infection. Subsequently, LM can induce type I interferon (IFN-I) production primarily in the spleen, which acts systemically on neutrophils to hamper their swarming by deactivating the ERK pathway, thus evading neutrophil-mediated eradication. Furthermore, our findings suggest that virus-induced IFN-I suppresses neutrophil swarming, and COVID-19 patients exhibit impaired neutrophil aggregation function. In conclusion, our findings provide compelling evidence demonstrating that intracellular bacteria represented by LM can hijack host defense mechanisms against viral infections to evade immune surveillance. Additionally, impaired neutrophil swarming caused by IFN-I is one of the significant factors contributing to the increased susceptibility to bacterial infections following viral infections. Intracellular bacterial infection triggers numerous innate immune responses. Here, Li et al. use intravital imaging to understand how L. monocytogenes invades the liver and avoids triggering neutrophil swarming. [ABSTRACT FROM AUTHOR]

Background and aims: Myofibroblasts, the primary producers of extracellular matrix, primarily originate from hepatic stellate cells (HSCs), and their activation plays a pivotal role in liver fibrosis. This study aimed to investigate the function of CXC motif ligand 14 (CXCL14) in the progression of liver fibrosis. Approach and results: CXCL14 knockdown significantly reduced the extent of liver fibrosis. Using Ingenuity pathway analysis and qRT‐PCR, activating transcription factor 3 (ATF3) was identified as a key upstream regulator of CXCL14 expression. Mechanistically, ATF3 was shown to bind to the CXCL14 promoter, promoting its transactivation by TGF‐β in HSCs. Notably, both global CXCL14 deletion (CXCL14−/−) and HSC/myofibroblast‐specific CXCL14 knockdown significantly attenuated liver fibrosis in mice. RNA‐seq comparisons between CXCL14−/− and WT mice highlighted Jak2 as the most significantly downregulated gene, implicating its role in the antifibrotic effects of CXCL14 suppression on HSC inactivation. Moreover, Jak2 overexpression reversed the inhibition of liver fibrosis caused by CXCL14 knockdown in vivo. Conclusions: These findings unveil a novel ATF3/CXCL14/Jak2 signalling axis in liver fibrosis, presenting potential therapeutic targets for the disease. [ABSTRACT FROM AUTHOR]

Activation of extracellular matrix–producing hepatic stellate cells (HSCs) is a key event in liver fibrogenesis. We showed that the expression of the heme-thiolate monooxygenase cytochrome P450 1B1 (CYP1B1) was elevated in human and mouse fibrotic livers and activated HSCs. Systemic or HSC-specific ablation and pharmacological inhibition of CYP1B1 attenuated HSC activation and protected male but not female mice from thioacetamide (TAA)–, carbon tetrachloride (CCl4)–, or bile duct ligation (BDL)–induced liver fibrosis. Metabolomic analysis revealed an increase in the disaccharide trehalose in CYP1B1-deficient HSCs resulting from intestinal suppression of the trehalose-metabolizing enzyme trehalase, whose gene we found to be a target of RARα. Trehalose or its hydrolysis-resistant derivative lactotrehalose exhibited potent antifibrotic activity in vitro and in vivo by functioning as an HSC-specific autophagy inhibitor, which may account for the antifibrotic effect of CYP1B1 inhibition. Our study thus reveals an endobiotic function of CYP1B1 in liver fibrosis in males, mediated by liver-intestine cross-talk and trehalose. At the translational level, pharmacological inhibition of CYP1B1 or the use of trehalose/lactotrehalose may represent therapeutic strategies for liver fibrosis. Editor's summary: Hepatic stellate cells (HSCs) are well-known actors in liver fibrosis, and a better understanding of the factors governing their activity could open up therapeutic opportunities. Tung et al. examined the role of the cytochrome P450 analog CYP1B1 in liver fibrosis, finding that its inhibition or depletion reduced liver pathology in multiple mouse models in a sex-dependent manner. The authors tied the observed antifibrotic effect in males to HSC accumulation of trehalose as a result of inhibition of trehalase in the intestine. As a test of therapeutic potential, male mice fed trehalose or nonhydrolyzable lactotrehalose in drinking water showed reduced liver fibrogenesis, with follow-up analysis of similarly treated HSCs demonstrating reduced autophagic degradation. This study suggests that the metabolite trehalose may play a sex-specific role in liver fibrosis. —Catherine Charneski [ABSTRACT FROM AUTHOR]

Non-alcoholic fatty liver disease (NAFLD) and its more advanced form, nonalcoholic steatohepatitis (NASH), have become global health challenges with significant morbidity and mortality rates. NAFLD encompasses several liver diseases, ranging from simple steatosis to more severe inflammatory and fibrotic forms. Ultimately, this can lead to liver cirrhosis and hepatocellular carcinoma. The intricate role of hepatic macrophages, particularly Kupffer cells (KCs) andmonocyte-derivedmacrophages (MoMFs), in the pathogenesis of NAFLD and NASH, has received increasing attention. Hepatic macrophages can interact with hepatocytes, hepatic stellate cells, and endothelial cells, playing a crucial role inmaintaining homeostasis. Paradoxically, they also participate in the pathogenesis of some liver diseases. This review highlights the fundamental role of hepatic macrophages in the pathogenesis of NAFLD and NASH, emphasizing their plasticity and contribution to inflammation and fibrosis, and hopes to provide ideas for subsequent experimental research and clinical treatment. [ABSTRACT FROM AUTHOR]

Background: The adenosine-adenosine receptor pathway plays important roles in the immune system and inflammation. Four adenosine receptors (i.e., A1R, A2AR, A2BR, and A3R) have been identified. However, the roles of these receptors were different in the disease progress and even play opposite roles in the same disease. This study aims to investigate the roles of A1R/A2AR/A2BR/A3R activation in liver fibrosis. Methods: Intraperitoneal injection of CCl4 into C57BL/6 mice was used to induce liver fibrosis in the models. Adenosine receptor agonists CCPA, CGS21680, BAY 60-6583, and namodenoson were used for A1R/A2AR/A2BR/A3R activation, respectively. Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels were used to evaluate the liver function. Hematoxylin and eosin (H&E) staining was used to investigate the pathological damage. Masson staining and Sirius Red staining were performed to evaluate the degree of collagen deposition. CCK8 and scratch assays were used to investigate the proliferation and migration ability of hepatic stellate cells (HSCs). Results: By using liver fibrosis mouse models, we observed that the A1R and A2AR agonists aggravated liver fibrosis, characterized by increasing ALT and AST levels, more serious liver pathological damage, and collagen deposition. However, the A2BR and A3R agonists alleviated liver fibrosis. Moreover, the A1R and A2AR agonist treatment promotes the proliferation and migration of HSC line LX2, while A2BR and A3R agonist treatment inhibited LX2 proliferation and migration. Consistently, A1R and A2AR agonist treatment elevated the expression of a-SMA and Col1a1 in LX2, whereas A2BR and A3R agonist treatment inhibited the expression of a-SMA and Col1a1 in LX2 cells. Additionally, 5'-N-ethylcarboxamidoadenosine (NECA), a metabolically stable adenosine analog, alleviated liver fibrosis and inhibited LX2 cell activity, proliferation, and migration. Conclusion: This study demonstrated the different roles of A1R/A2AR/A2BR/A3R during liver fibrosis development via regulating the HSC activity and proliferation. [ABSTRACT FROM AUTHOR]

Both DNA 5-methylcytosine (5mC) and RNA N6-methyladenosine (m6A) modifications are reported to participate in cellular stress responses including inflammation. Phosphoenolpyruvate carboxykinase 2 (PCK2) is upregulated in Kupffer cells (KCs) to facilitate the proinflammatory phosphorylation signaling cascades upon LPS stimulation, yet the role of 5mC and m6A in PCK2 upregulation remain elusive. Here, we report that the significantly augmented PCK2 mRNA and protein levels are associated with global 5mC demethylation coupled with m6A hypermethylation in LPS-activated KCs. The suppression of 5mC demethylation or m6A hypermethylation significantly alleviates the upregulation of PCK2 and proinflammatory cytokines in LPS-challenged KCs. Further reciprocal tests indicate 5mC demethylation is upstream of m6A hypermethylation. Specifically, CpG islands in the promoters of PCK2 and RNA methyltransferase (METTL3 and METTL14) genes are demethylated, while the 3′UTR of PCK2 mRNA is m6A hypermethylated, in LPS-stimulated KCs. These modifications contribute to the transactivation of the PCK2 gene as well as increased PCK2 mRNA stability and protein production via a m6A-mediated mechanism with IGF2BP1 as the reader protein. These results indicate that DNA 5mC and RNA m6A collaborate to upregulate PCK2 expression, respectively, at the transcriptional and post-transcriptional levels during KC activation. [ABSTRACT FROM AUTHOR]

Proinflammatory hepatic macrophage activation plays a key role in the development of nonalcoholic steatohepatitis (NASH). This involves increased embryonic hepatic Kupffer cell (KC) death, facilitating the replacement of KCs with bone marrow–derived recruited hepatic macrophages (RHMs) that highly express proinflammatory genes. Moreover, phago/efferocytic activity of KCs is diminished in NASH, enhancing liver inflammation. However, the molecular mechanisms underlying these changes in KCs are not known. Here, we show that hypoxia-inducible factor 2α (HIF-2α) mediates NASH-associated decreased KC growth and efferocytosis by enhancing lysosomal stress. At the molecular level, HIF-2α stimulated mammalian target of rapamycin (mTOR)– and extracellular signal–regulated kinase-dependent inhibitory transcription factor EB (TFEB) phosphorylation, leading to decreased lysosomal and phagocytic gene expression. With increased metabolic stress and phago/efferocytic burden in NASH, these changes were sufficient to increase lysosomal stress, causing decreased efferocytosis and lysosomal cell death. Of interest, HIF-2α–dependent TFEB regulation only occurred in KCs but not RHMs. Instead, in RHMs, HIF-2α promoted mitochondrial reactive oxygen species production and proinflammatory activation by increasing ANT2 expression and mitochondrial permeability transition. Consequently, myeloid lineage–specific or KC-specific HIF-2α depletion or the inhibition of mTOR-dependent TFEB inhibition using antisense oligonucleotide treatment protected against the development of NASH in mice. Moreover, treatment with an HIF-2α–specific inhibitor reduced inflammatory and fibrogenic gene expression in human liver spheroids cultured under a NASH-like condition. Together, our results suggest that macrophage subtype–specific effects of HIF-2α collectively contribute to the proinflammatory activation of liver macrophages, leading to the development of NASH. Editor's summary: Abberant hepatic macrophage activity has been implicated in NASH development, but the mechanism of this immune dysregulation is unclear. Jeelani et al. show that a hypoxia-inducible factor, HIF-2α, promotes differential effects on macrophage subpopulations during NASH in obesity. HIF-2α suppressed the growth and function of endogenous liver macrophages (Kupffer cells) but increased the proinflammatory activation of the myeloid-derived macrophages that are subsequently recruited to the liver and that start to replace the Kupffer cells. HIF-2α–specific approaches in a murine NASH model and human organoids suggested that this disease biology may be therapeutically targetable. —Catherine Charneski [ABSTRACT FROM AUTHOR]

Liver fibrosis is a serious global health issue for which effective treatment remains elusive. Chemical-induced hepatocyte-like cells (ciHeps) have emerged as an appealing source for cell transplantation therapy, although they present several challenges such as the risk of lung thromboembolism or hemorrhage. Apoptotic vesicles (apoVs), small membrane vesicles generated during the apoptosis process, have gained attention for their role in regulating various physiological and pathological processes. In this study, we generated ciHep-derived apoVs (ciHep-apoVs) and investigated their therapeutic potential in alleviating liver fibrosis. Our findings revealed that ciHep-apoVs induced the transformation of macrophages into an anti-inflammatory phenotype, effectively suppressed the activity of activated hepatic stellate cells (aHSCs), and enhanced the survival of hepatocytes. When intravenously administered to mice with liver fibrosis, ciHep-apoVs were primarily engulfed by macrophages and myofibroblasts, leading to a reduction in liver inflammation and fibrosis. Proteomic and miRNA analyses showed that ciHep-apoVs were enriched in various functional molecules that modulate crucial cellular processes, including metabolism, signaling transduction, and ECM-receptor interactions. ciHep-apoVs effectively suppressed aHSCs activity through the synergistic inhibition of glycolysis, the PI3K/AKT/mTOR pathway, and epithelial-to-mesenchymal transition (EMT) cascades. These findings highlight the potential of ciHep-apoVs as multifunctional nanotherapeutics for liver fibrosis and provide insights into the treatment of other liver diseases and fibrosis in other organs. [ABSTRACT FROM AUTHOR]

In this study, we examined the effects of experimental intraperitoneal infection with haemotropic Mycoplasma ovis (0.5 mL of blood containing 80% parasitaemia) on selected serum biomarkers and cellular pathology in mice. After infection, M. ovis cells appeared in the blood films within one week. A dose-dependent peak of parasitemia was observed during the 3rd-week post-infection (pi), with a significant decrease in mean PCV between treatment versus control group at week 3 (t14 = -3.693, P < 0.02), week 5 (t14 = -2.096, P = 0.055), and week 7 (t14 = -4.329, P = 0.0 01). There was a significantly (t8 = -2.330, P = 0.048) lower serum oestrogen in treatment (10.38 ± 5.07) than control (17.43 ± 4.48), while serum progesterone was significantly (t8 = 5.415, P = 0.001) increased in treatment (27.37 ± 2.17) than control (15.92 ± 4.20). Serum haptoglobin was significantly (t8 = 8.525, P < 0.01) lower in treatment (8.72 ± 1.49) than control (18.16 ± 1.98) while the SAA was significantly (t8 = 3.362, P = 0.01) higher in treatment (16.79 ± 2.71) than control (11.59 ± 2.15). Prominent lesions observed in the ovary include degeneration, necrosis, vacuolation, and hypertrophy of the lutein cells in corpora lutea. In the lymph nodes, diffused cellular hyperplasia of the lymphoid tissue in the cortex. In the liver, degeneration and necrosis accompanied by leucocytic cellular infiltration and Kupffer cell proliferation within the sinusoids. There were diffused leucocytic infiltrations and proliferative lesions in the glomerulus of the kidneys. The disturbance in progesterone and ovarian pathology highlights the potential role of haemotropic M. ovis in reproductive disorders. The observed changes in biomarkers and cellular reactions following M. ovis infection in the mouse may be further advanced in sheep and goats. [ABSTRACT FROM AUTHOR]

While macrophage heterogeneity during metabolic dysfunction-associated steatohepatitis (MASH) has been described, the fate of these macrophages during MASH regression is poorly understood. Comparing macrophage heterogeneity during MASH progression vs regression, we identified specific macrophage subpopulations that are critical for MASH/fibrosis resolution. We elucidated the restorative pathways and gene signatures that define regression-associated macrophages and establish the importance of TREM2+ macrophages during MASH regression. Liver-resident Kupffer cells are lost during MASH and are replaced by four distinct monocyte-derived macrophage subpopulations. Trem2 is expressed in two macrophage subpopulations: i) monocyte-derived macrophages occupying the Kupffer cell niche (MoKC) and ii) lipid-associated macrophages (LAM). In regression livers, no new transcriptionally distinct macrophage subpopulation emerged. However, the relative macrophage composition changed during regression compared to MASH. While MoKC was the major macrophage subpopulation during MASH, they decreased during regression. LAM was the dominant macrophage subtype during MASH regression and maintained Trem2 expression. Both MoKC and LAM were enriched in disease-resolving pathways. Absence of TREM2 restricted the emergence of LAMs and formation of hepatic crown-like structures. TREM2+ macrophages are functionally important not only for restricting MASH-fibrosis progression but also for effective regression of inflammation and fibrosis. TREM2+ macrophages are superior collagen degraders. Lack of TREM2+ macrophages also prevented elimination of hepatic steatosis and inactivation of HSC during regression, indicating their significance in metabolic coordination with other cell types in the liver. TREM2 imparts this protective effect through multifactorial mechanisms, including improved phagocytosis, lipid handling, and collagen degradation. [ABSTRACT FROM AUTHOR]

Introduction: Liver fibrosis is primarily driven by the activation of hepatic stellate cells (HSCs), which involves various epigenetic modifications. Objectives: N6‐methyladenosine (m6A), the most prevalent RNA modification in eukaryotic cells, influences numerous physiological and pathological processes. Nevertheless, the role of insulin‐like growth factor 2 mRNA‐binding protein 3 (IGF2BP3), a reader gene mediating m6A modifications, in liver fibrosis remains unclear. Methods and results: This study demonstrated that IGF2BP3 knockout reduces liver fibrosis by promoting HSC ferroptosis (FPT) and inactivating HSCs. Multi‐omics analysis revealed that HSC‐specific IGF2BP3 knockout decreased m6A content in Jagged1 (Jag1), a key component of the Notch signalling pathway. Furthermore, IGF2BP3 deficiency significantly reduced the expression of hairy and enhancer of split‐1 (Hes1), a transcription factor in the Notch/Jag1 signalling pathway, with mRNA levels declining to 35%–62% and protein levels to 28%–35%. Additionally, it suppressed glutathione peroxidase 4 (GPX4) (decreased to approximately 31%–38%), a negative regulator of FPT, thereby facilitating HSC FPT progression and reducing profibrotic gene expression. Conclusion: These findings uncover a novel IGF2BP3/Notch/Jag1 signalling pathway involving HSC FPT, suggesting promising targets for ameliorating liver fibrosis. Key Points/Highlights: IGF2BP3 deficiency inactivates Jag1 signalling.IGF2BP3 deficiency‐mediated m6A modifications promote HSC ferroptosis.IGF2BP3 inhibition facilitates ferroptosis in HSCs via the Hes1/GPX4 axis.IGF2BP3 deficiency inactivates Jag1/Notch1/3/Hes1 signalling pathway inactivation, leading to the decrease in GPX4, which contributes to HSC ferroptosis. [ABSTRACT FROM AUTHOR]

DNA nanostructures, known for their programmability, ease of modification, and favourable biocompatibility, have gained widespread application in the biomedical field. Among them, Tetrahedral DNA Origami (TDOs), as a novel DNA nanostructure, possesses well‐defined structures, multiple modification sites, and large cavities, making it a promising drug carrier. However, current understanding of TDOs' interactions with biological systems, particularly with target cells and organs, remains unexplored, limiting its further applications in biomedicine. In this work, we prepared TDOs with an average particle size of 40 nm and labelled them with Cy5 fluorescent molecules. Following intravenous injection in mice, the uptake of TDOs by different types of liver and kidney cells was observed. Results indicated that TDOs accumulate in renal tubules and are metabolized by Kupffer cells, epithelial cells, and hepatocytes in the liver. Additionally, in a tumour‐bearing mouse model, TDOs passively targeted tumour tissues and exhibited excellent tumour penetration and retention after rapid metabolism in hepatocytes. Our findings provide crucial insights for the development of TDO‐based drug delivery systems. [ABSTRACT FROM AUTHOR]

Cholestasis is a common clinical event in which bile formation and excretion are blocked, leading to retention of bile acids or bile salts; whether it occurs intra- or extrahepatically, primary or secondary, its pathogenesis is still unclear and is influenced by a combination of factors. In a variety of inflammatory and immune cells such as neutrophils, macrophages (intrahepatic macrophages are also known as Kupffer cells), mast cells, NK cells, and even T cells in humoral immunity and B cells in cellular immunity, inflammation can be a "second strike" against cholestatic liver injury. These cells, stimulated by a variety of factors such as bile acids, inflammatory chemokines, and complement, can be activated and accumulate in the cholestatic liver, and with the involvement of inflammatory mediators and modulation by cytokines, can lead to destruction of hepatocytes and bile duct epithelial cells and exacerbate (and occasionally retard) the progression of cholestatic liver disease. In this paper, we summarized the new research advances proposed so far regarding the relationship between inflammation and cholestasis, aiming to provide reference for researchers and clinicians in the field of cholestatic liver injury research. [ABSTRACT FROM AUTHOR]

Intrahepatic accumulation dominates organ distribution for most nanomedicines. However, obscure intrahepatic fate largely hampers regulation on their in vivo performance. Herein, PEGylated liposomal doxorubicin is exploited to clarify the intrahepatic fate of both liposomes and the payload in male mice. Kupffer cells initiate and dominate intrahepatic capture of liposomal doxorubicin, following to deliver released doxorubicin to hepatocytes with zonated distribution along the lobule porto-central axis. Increasing Kupffer cells capture promotes doxorubicin accumulation in hepatocytes, revealing the Kupffer cells capture-payload release-hepatocytes accumulation scheme. In contrast, free doxorubicin is overlooked by Kupffer cells, instead quickly distributing into hepatocytes by directly crossing fenestrated liver sinusoid endothelium. Compared to free doxorubicin, liposomal doxorubicin exhibits sustained metabolism/excretion due to the extra capture-release process. This work unveils the pivotal role of Kupffer cells in intrahepatic traffic of PEGylated liposomal therapeutics, and quantitively describes the intrahepatic transport/distribution/elimination process, providing crucial information for guiding further development of nanomedicines. Here, authors looked at the roles of Kupffer cells in determining intrahepatic traffic of PEGylated liposomal doxorubicin, providing information for design and clinical applications of liposomal therapeutics. [ABSTRACT FROM AUTHOR]

Nonalcoholic steatohepatitis (NASH) and alcoholic hepatitis (AH) affect a large part of the general population worldwide. Dysregulation of lipid metabolism and alcohol toxicity drive disease progression by the activation of hepatic stellate cells and the capillarization of liver sinusoidal endothelial cells. Collagen deposition, along with sinusoidal remodeling, alters sinusoid structure, resulting in hepatic inflammation, portal hypertension, liver failure, and other complications. Efforts were made to develop treatments for NASH and AH. However, the success of such treatments is limited and unpredictable. We report a strategy for NASH and AH treatment involving the induction of integrin αvβ3-mediated cell apoptosis using a rationally designed protein (ProAgio). Integrin αvβ3 is highly expressed in activated hepatic stellate cells (αHSCs), the angiogenic endothelium, and capillarized liver sinusoidal endothelial cells (caLSECs). ProAgio induces the apoptosis of these disease-driving cells, therefore decreasing collagen fibril, reversing sinusoid remodeling, and reducing immune cell infiltration. The reversal of sinusoid remodeling reduces the expression of leukocyte adhesion molecules on LSECs, thus decreasing leukocyte infiltration/activation in the diseased liver. Our studies present a novel and effective approach for NASH and AH treatment. [ABSTRACT FROM AUTHOR]

Metabolic dysfunction-associated steatohepatitis (MASH), previously called non-alcoholic steatohepatitis (NASH), is a growing concern worldwide, with liver fibrosis being a critical determinant of its prognosis. Monocyte-derived macrophages have been implicated in MASH-associated liver fibrosis, yet their precise roles and the underlying differentiation mechanisms remain elusive. In this study, we unveil a key orchestrator of this process: long chain saturated fatty acid-Egr2 pathway. Our findings identify the transcription factor Egr2 as the driving force behind monocyte differentiation into hepatic lipid-associated macrophages (hLAMs) within MASH liver. Notably, Egr2-deficiency reroutes monocyte differentiation towards a macrophage subset resembling resident Kupffer cells, hampering hLAM formation. This shift has a profound impact, suppressing the transition from benign steatosis to liver fibrosis, demonstrating the critical pro-fibrotic role played by hLAMs in MASH pathogenesis. Long-chain saturated fatty acids that accumulate in MASH liver emerge as potent inducers of Egr2 expression in macrophages, a process counteracted by unsaturated fatty acids. Furthermore, oral oleic acid administration effectively reduces hLAMs in MASH mice. In conclusion, our work not only elucidates the intricate interplay between saturated fatty acids, Egr2, and monocyte-derived macrophages but also highlights the therapeutic promise of targeting the saturated fatty acid-Egr2 axis in monocytes for MASH management. Egr2 plays a central role in driving the differentiation of monocytes into hLAMs in MASH liver. [ABSTRACT FROM AUTHOR]

Background and aims: Metabolic dysfunction-associated steatohepatitis (MASH) is a significant health concern with limited treatment options. AXL, a receptor tyrosine kinase activated by the GAS6 ligand, promotes MASH through activation of hepatic stellate cells and inflammatory macrophages. This study identified cell subsets affected by MASH progression and the effect of AXL inhibition. Methods: Mice were fed chow or different fat-enriched diets to induce MASH, and small molecule AXL kinase inhibition with bemcentinib was evaluated. Gene expression was measured by qPCR. Time-of-flight mass cytometry (CyTOF) used single cells from dissociated livers, acquired on the Fluidigm Helios, and cell populations were studied using machine learning. Results: In mice fed different fat-enriched diets, liver steatosis alone was insufficient to elevate plasma soluble AXL (sAXL) levels. However, in conjunction with inflammation, sAXL increases, serving as an early indicator of steatohepatitis progression. Bemcentinib, an AXL inhibitor, effectively reduced proinflammatory responses in MASH models, even before fibrosis appearance. Utilizing CyTOF analysis, we detected a decreased population of Kupffer cells during MASH while promoting infiltration of monocytes/macrophages and CD8+ T cells. Bemcentinib partially restored Kupffer cells, reduced pDCs and GzmB-NK cells, and increased GzmB+CD8+ T cells and LSECs. Additionally, AXL inhibition enhanced a subtype of GzmB+CD8+ tissue-resident memory T cells characterized by CX3CR1 expression. Furthermore, bemcentinib altered the transcriptomic landscape associated with MASH progression, particularly in TLR signaling and inflammatory response, exhibiting differential cytokine expression in the plasma, consistent with liver repair and decreased inflammation. Conclusion: Our findings highlight sAXL as a biomarker for monitoring MASH progression and demonstrate that AXL targeting shifted liver macrophages and CD8+ T-cell subsets away from an inflammatory phenotype toward fibrotic resolution and organ healing, presenting a promising strategy for MASH treatment. [ABSTRACT FROM AUTHOR]

The main focus of in vitro toxicity assessment methods is to assess the viability of the cells, which is usually based on metabolism changes. Yet, when exposed to toxic substances, the cell triggers multiple signals in response. With this in mind, we have developed a promising cell-based toxicity method that observes various cell responses when exposed to toxic substances (either death, division, or remain viable). Based on the collective cell response, we observed and predicted the dynamics of the cell population to determine the toxicity of the toxicant. The method was tested with two different conformations: In the first conformation, we exposed a monoculture model of blood macrophages to UV light, hydrogen peroxide, nutrient deprivation, tetrabromobisphenol A, fatty acids, and 5-fluorouracil. In the second, we exposed a coculture liver model consisting of hepatocytes, hepatic stellate cells, Kupffer cells, and liver sinusoidal endothelial cells to rifampicin, ibuprofen, and 5-fluorouracil. The method showed good accuracy compared to established toxicity assessment methods. In addition, this approach provided more representative information on the toxic effects of the compounds, as it considers the different cellular responses induced by toxic agents. [ABSTRACT FROM AUTHOR]

Objective: Pistacia vera is commonly used in traditional medicine to treat various disorders. This study aims to investigate the antianemia and hepatoprotective effects of Pistacia vera pericarp extract (PVPE) in a rat model of phenylhydrazine (PHZ)-induced anemia. Materials and Methods: PVPE was prepared using the maceration method. The extract was administered at doses of 20, 80, and 160 mg/kg for 28 days to normal and PHZ-treated rats. The effects of PVPE were evaluated in terms of changes in biochemical, histological, hematological, and molecular biomarkers in the liver and blood. Results: Administration of PVPE to the anemic animals significantly restored these deleterious effects on hematological parameters compared to the anemic group. Kupffer cell activation was seen in the liver tissue of the anemic rats. Administration of PVPE mitigated these deleterious effects. Conclusion: PVPE has potent antioxidant activity and may represent a promising treatment for anemia and liver protection in clinical settings. [ABSTRACT FROM AUTHOR]

Background: Heavy elements such as antimony greatly affect the environment and living organisms. Antimony is discharged into the environment by mining and industries that use it as pesticides and flame retardants. This activity can lead to environmental pollution, water and soil contamination. Antimony can also accumulate in living organisms and cause negative health effects, such as damage to the respiratory system and skin, and growth abnormalities of animals and plants. Methods: The primary objective of this investigation was to explore the teratogenic impact of the antimony heavy metal on histological structure of the liver in adult rabbits (Oryctolagus cuniculus). The study included 21 adult white rabbits divided into several groups: the first one is the control group injected with physiological saline (0.09% NaCl), the other group injected with 20 mg/kg antimony, and the last injected with 30 mg/kg antimony over a 30-day period. Following this, postmortem procedures were conducted to extract and fix the liver organ, and tissue sections were prepared. Result: The results revealed significant histological changes, including distortion and rupture in Glisson's Capsule, leading to the formation of a sub-capsular space due to its separation from hepatocytes. Additionally, alterations in the radial organization of hepatocytes and pyknosis in the nuclei were observed, characterized by a dark color and reduced size. Karyolysis, where nuclei completely disappeared, and hydropic degeneration in hepatocytes with swollen appearance and dark nuclei due to fluid accumulation were noted. Moreover, an increase in Kupffer cells and blood congestion in the central vein, resulting in dilation compared to the control group, were observed. Conclusion: Overall, the treatment with antimony at 20 and 30 mg/g doses for 30 days show profound teratogenic effects on the histological structure of the liver in adult rabbits. These effects are represented by the destruction of various parts of liver, in addition to changes in arrangement, and distortion and rupture of the cells. Furthermore, an increase in Kupffer cells and blood congestion were also recorded. [ABSTRACT FROM AUTHOR]

Liver fibrosis is a pathological process of various liver diseases, and a large number of studies have shown that liver fibrosis is reversible. Natural products are important sources of drugs for treating liver fibrosis. The present study evaluated the protective effect of cycloastragenol (CAG) on liver fibrosis and the underlying mechanisms. The mouse model of liver fibrosis was established by intraperitoneal injection of carbon tetrachloride (CCl4) and olive oil. Subsequently, CAG was administered orally at different doses (2.5 mg/kg/d, 5 mg/kg/d, 10 mg/kg/d), and the degree of liver fibrosis was assessed using hematoxylin-eosin, Van Gieson, and Sirius Red staining. Alanine aminotransferase, aspartate aminotransferase, hyaluronic acid, and hydroxyproline levels were detected using biochemical analyses. The mRNA and protein expression levels of α-SMA, LC3, P62, PI3K, Akt, and mTOR in the liver tissue were assessed by reverse-transcription polymerase chain reaction and western blot, respectively. The expression of fibrogenesis-related marker α-SMA in the liver tissue was assessed using immunofluorescence. As expected, CAG alleviated liver fibrosis and suppressed hepatic stellate cell activation. And then, CAG inhibited autophagy and activated the PI3K/Akt/mTOR signaling pathway. Thus, CAG attenuated CCI4-induced liver fibrosis in mice by inhibiting autophagy and activating the PI3K/Akt/mTOR signaling pathway. [ABSTRACT FROM AUTHOR]

The existing in vitro toxicological models lack translational potential, which makes difficult the application of gathered information to clinical usage. To tackle this issue, we built a model with four different types of primary liver cells: hepatic sinusoidal endothelial cells, hepatic stellate cells, Kupffer cells and hepatocytes. We cultured them in different combinations of composition and volumes of cell medium, hepatocyte proportions of total cells and additions of extracellular matrixes. We added rifampicin (RIF), ibuprofen (IBU) and 5-fluorouracil (5-FU) to this model and observed the microanatomy and physiology changes for a week with preclinical and clinical instruments. Among the different model configurations, we selected the feature combination of the in vitro model that had similar biomarker values to those measured in clinical diagnostics. When we exposed the selected model configuration to RIF, IBU and 5-FU, we observed similar glucose, triglyceride and albumin dynamics as in vivo (from clinical data). Therefore, we have built an in vitro liver model that resembles the liver microenvironment, and we have analysed it with clinical instrumentation to facilitate data translation. Furthermore, during these observations, we found that Kupffer and LSEC cells are suitable candidates for the search for clinical diagnostic markers of liver function. [ABSTRACT FROM AUTHOR]

Healthy livers contain 80% of body resident macrophages known as Kupffer cells. In diseased livers, the number of Kupffer cells usually drops but is compensated by infiltration of monocyte-derived macrophages, some of which can differentiate into Kupffer-like cells. Early studies suggest that Kupffer cells play important roles in both promoting liver injury and liver regeneration. Yet, the distinction between the functionalities of resident and infiltrating macrophages is not always made. By using more specific macrophage markers and targeted cell depletion and single-cell RNA sequencing, recent studies revealed several subsets of monocyte-derived macrophages that play important functions in inducing liver damage and inflammation as well as in liver repair and regeneration. In this review, we discuss the different roles that hepatic macrophages play in promoting necrotic liver lesion resolution and dead cell clearance, as well as the targeting of these cells as potential tools for the development of novel therapies for acute liver failure and acute-on-chronic liver failure. [ABSTRACT FROM AUTHOR]

The article provides an overview of immune cell development and differentiation in liver diseases, emphasizing the liver's role as a key site for these processes. Topics discussed include the impact of macrophage polarization on inflammation and tissue damage in hepatitis, the role of immune cells in liver fibrosis and cancer, and the dual functions of immune cells in liver transplantation.

The article focuses on the development and utility of the BAC-Alb-FlpO transgenic mouse line as a novel tool for liver disease research. Topics include its ability to express FlpO recombinase for high-efficiency genetic manipulation, its application in generating liver cancer models, and its potential combination with existing recombination systems for advanced studies on liver diseases.

Taking the hepatic sinusoid (HS) as the main delivery area of liver nutrients and metabolic waste, recognizing its structure is important for a deep understanding of liver function. In this paper, based on lycopersicon esculentum lectin (LEL), with targeting ability for endothelial cells, and carbon quantum dots (CQDs), with high biosafety, an LEL-coupled CQD immunofluorescence probe (CQD@LEL) that can label microvessels is designed and used for the fluorescence labeling and imaging of HS in liver tissue sections. The CQD size is approximately 2 nm. Blue fluorescence is emitted under excitation; its optimal excitation wavelength is 400 nm while the emission is at about 450 nm. Gel electrophoresis and capillary electrophoresis confirm that glutaraldehyde can couple LEL to CQD, and the obtained CQD@LEL retains the fluorescence property and has good stability. Optimization experiments show that its labeling effect is positively correlated with time and probe concentration for dyeing the blood vessels of mouse liver slices. In order to improve the effect further, a probe concentration of 0.17 mg mL−1 and incubation time of 3 h were chosen to label the liver tissue sections. The results show that the liver microvessels are formed by interstitial structures among the hepatic cords, and the HS presents a granular or patchy appearance. H&E and ultrathin section TEM show that the microvascular wall of the liver is composed of discontinuous endothelial cells, and there are Kupffer cells and other cells in the tubes, proving that our probe can clearly label the structure and morphology of liver microvessels. This work is of great significance for the visualization of HS. [ABSTRACT FROM AUTHOR]

Liver fibrosis is characterized by the activation and transformation of hepatic stellate cells (HSCs) induced by various injury factors. The degree of liver fibrosis can be significantly improved, but persistent injury factors present a significant therapeutic challenge. Hepatocytes are the most important parenchymal cell type in the liver. In this study, we explored the molecular mechanisms by which damaged liver cells activate HSCs through extracellular vesicles. We established a coculture model of LO2 and LX2 and validated its exosomal transmission activity. Subsequently, differentially expressed long noncoding RNAs (lncRNAs) were screened through RNA sequencing and their mechanisms of action as competing endogenous RNAs (ceRNAs) further confirmed using biological methods, such as FISH and luciferase assays. Damaged liver cells induced activation of LX2 and upregulation of liver fibrosis‐related markers. Exosomes extracted and identified from the supernatant fraction contained differentially expressed lncRNA cytoskeleton regulator RNA (CYTOR) that competed with microRNA‐125 (miR‐125) for binding to glial cell line‐derived neurotrophic factor (GDNF) in HSCs, in turn, promoting LX2 activation. MiR‐125 could target and regulate both CYTOR and GDNF and vice versa, as verified using the luciferase assay. In an in vivo model, damaged liver extracellular vesicles induced the formation of liver fibrosis. Notably, downregulation of CYTOR within extracellular vesicles effectively inhibited liver fibrosis. The lncRNA CYTOR in exosomes of damaged liver cells is upregulated and modulates the expression of downstream GDNF through activity as a ceRNA, providing an effective mechanism for activation of HSCs. [ABSTRACT FROM AUTHOR]

Aim of the study: Metabolic associated steatotic liver disease (MASLD) is one of the most frequent chronic liver diseases in the world; macrophage activation is reflected by increased expression of CD163, which sheds as serum soluble CD163 that is linked to hepatic steatosis, inflammation, and fibrosis. Aim of the study was assessment of liver macrophage activation and hepatic histopathological changes in patients with MASLD. Material and methods: A total of 30 patients with MASLD and equal numbers of age- and sex-matched healthy controls were enrolled in the study. Quantitative serum levels of soluble CD163 (sCD163) were determined using a commercially available standard sandwich ELISA kit. Core liver biopsies were obtained from patients with MASLD and evaluation of CD163 using anti-CD163 Ab-1 (Clone 10D6) - mouse monoclonal antibody. Results: The median sCD163 level was significantly higher in patients with MASLD compared with healthy controls. It can discriminate patients with MASLD from healthy controls at a cut-off value of 814 pg/ml. sCD163 level and intrahepatic total CD163-positive cell count were positively correlated, and both showed positive correlations with nonalcoholic fatty liver disease activity score. Conclusions: Soluble CD163 can discriminate MASLD patients from healthy controls after the exclusion of other causes of inflammation. [ABSTRACT FROM AUTHOR]

Background and aims: A complete understanding of disease pathophysiology in advanced liver disease is hampered by the challenges posed by clinical specimen collection. Notably, in these patients, a transjugular liver biopsy (TJB) is the only safe way to obtain liver tissue. However, it remains unclear whether successful sequencing of this extremely small and fragile tissue can be achieved for downstream characterization of the hepatic landscape. Methods: Here we leveraged in-house available single-cell RNA-sequencing (scRNA-seq) and single-nucleus (snRNA-seq) technologies and accompanying tissue processing protocols and performed an in-patient comparison on TJB's from decompensated cirrhosis patients (n = 3). Results: We confirmed a high concordance between nuclear and whole cell transcriptomes and captured 31,410 single nuclei and 6,152 single cells, respectively. The two platforms revealed similar diversity since all 8 major cell types could be identified, albeit with different cellular proportions thereof. Most importantly, hepatocytes were most abundant in snRNA-seq, while lymphocyte frequencies were elevated in scRNA-seq. We next focused our attention on hepatic myeloid cells due to their key role in injury and repair during chronic liver disease. Comparison of their transcriptional signatures indicated that these were largely overlapping between the two platforms. However, the scRNA-seq platform failed to recover sufficient Kupffer cell numbers, and other monocytes/macrophages featured elevated expression of stressrelated parameters. Conclusion: Our results indicate that single-nucleus transcriptome sequencing provides an effective means to overcome complications associated with clinical specimen collection and could sufficiently profile all major hepatic cell types including all myeloid cell subsets. [ABSTRACT FROM AUTHOR]

Over-consumption of fructose in adults and children has been linked to increased risk of non-alcoholic fatty liver disease (NAFLD). Recent studies have highlighted the effect of fructose on liver inflammation, fibrosis, and immune cell activation. However, little work summarizes the direct impact of fructose on macrophage infiltration, phenotype, and function within the liver. We demonstrate that chronic fructose diet decreased Kupffer cell populations while increasing transitioning monocytes. In addition, fructose increased fibrotic gene expression of collagen 1 alpha 1 (Col1a1) and tissue metallopeptidase inhibitor 1 (Timp1) as well as inflammatory gene expression of tumor necrosis factor alpha (Tnfa) and expression of transmembrane glycoprotein NMB (Gpnmb) in liver tissue compared to glucose and control diets. Single cell RNA sequencing (scRNAseq) revealed fructose elevated expression of matrix metallopeptidase 12 (Mmp12), interleukin 1 receptor antagonist (Il1rn), and radical S-adenosyl methionine domain (Rsad2) in liver and hepatic macrophages. In vitro studies using IMKC and J774.1 cells demonstrated decreased viability when exposed to fructose. Additionally, fructose increased Gpnmb, Tnfa, Mmp12, Il1rn, and Rsad2 in unpolarized IMKC. By mass spectrometry, C13 fructose tracing detected fructose metabolites in glycolysis and the pentose phosphate pathway (PPP). Inhibition of the PPP further increased fructose induced Il6, Gpnmb, Mmp12, Il1rn, and Rsad2 in nonpolarized IMKC. Taken together, fructose decreases cell viability while upregulating resolution and anti-inflammatory associated genes in Kupffer cells. [ABSTRACT FROM AUTHOR]

Although a lot of effort has been put into creating drugs and combination therapies against chronic hepatitis, no effective treatment has been established. Type-I interferon is a promising therapeutic for chronic hepatitis due to its excellent anti-inflammatory effects through interferon receptors on hepatic macrophages. To develop a type-I IFN equipped with the ability to target hepatic macrophages through the macrophage mannose receptor, the present study designed a mouse type-I interferon-mannosylated albumin fusion protein using site-specific mutagenesis and albumin fusion technology. This fusion protein exhibited the induction of anti-inflammatory molecules, such as IL-10, IL-1Ra, and PD-1, in RAW264.7 cells, or hepatoprotective effects on carbon tetrachloride-induced chronic hepatitis mice. As expected, such biological and hepatoprotective actions were significantly superior to those of human fusion proteins. Furthermore, the repeated administration of mouse fusion protein to carbon tetrachloride-induced chronic hepatitis mice clearly suppressed the area of liver fibrosis and hepatic hydroxyproline contents, not only with a reduction in the levels of inflammatory cytokine (TNF-α) and fibrosis-related genes (TGF-β, Fibronectin, Snail, and Collagen 1α2), but also with a shift in the hepatic macrophage phenotype from inflammatory to anti-inflammatory. Therefore, type-I interferon-mannosylated albumin fusion protein has the potential as a new therapeutic agent for chronic hepatitis. [ABSTRACT FROM AUTHOR]

Metabolic dysfunction-associated steatotic liver disease (MASLD) is closely related to some metabolic disorders, such as central obesity and type 2 diabetes (T2D). Glucagon-like peptide 1 receptor agonists (GLP-1RAs), such as semaglutide, may have therapeutic roles in MASLD associated with T2D. This study aims to investigate the molecular mechanisms underlying the effectiveness of semaglutide on MASLD in terms of progression from liver steatosis to fibrosis. We characterized exosomes from ten patients with type 2 diabetes (T2D) before (T0) and after 12 months (T12) of treatment with once-weekly subcutaneous semaglutide. Six of ten patients were considered responders to therapy (R) based on MASLD severity downgrading by at least one class according to a validated ultrasonographic (US) score. Normal hepatocytes (HEPA-RG) and stellate (LX-2) cells were challenged with exosomes from R and NR patients, isolated before and after 12 months of therapy. Exosomes from both R and NR patients isolated at T0 significantly affected LX-2 viability. After 12 months of treatment, only those isolated from R patients restored cell viability, whereas those from NR patients did not. No effects were observed on HEPA-RG cells. Exosomes at T12 from R but not from NR patients significantly decreased the production of α-SMA, a marker of LX-2 activation, a liver stellate cell model, and ph-SMAD2 and CTGF, involved in fibrosis processes. TGF-β1 was not modulated by the exosomes of R and NR patients. As a downstream effect, Vimentin, Collagen 1A1, and Fibronectin extracellular matrix components were also downregulated, as measured by droplets digital PCR. In conclusion, these results shed light on the potential effectiveness of semaglutide in improving liver fibrosis in MASLD. [ABSTRACT FROM AUTHOR]

The liver is a complex organ that governs many types of metabolisms, including energy metabolism and other cellular processes. The liver also plays a crucial role in important functions in immunity, and the activity of liver tissue-associated immunity affects the outcome of many liver pathologies. A thorough characterization of the liver immune microenvironment may contribute to a better understanding of immune signaling, the mechanisms of specific immune responses, and even to improved predictions about therapy outcomes. In this paper, we present an optimized, simple, and rapid protocol to characterize the liver-associated immune cell milieu. We believe that the most suitable technique for obtaining a complex immune cell suspension and for removing contaminating blood cells is to perform mouse liver perfusion, using only phosphate buffer saline. Combining an enzymatic digestion and a mechanical dissociation of liver tissue, followed by cell purification, improves downstream applications. This combination is an essential prerequisite for immune cell determination and characterization. We then demonstrate a flow cytometry-based multiparametric immunophenotyping along with a gating strategy to detect and quantify liver endothelial cells, T cells (helper and cytotoxic), B cells, NK cells, NKT cells, neutrophils, monocytes (subsets included), dendritic cells (subsets included), macrophages and Kupffer cells. [ABSTRACT FROM AUTHOR]

The liver is a key organ in the pharmacokinetics of iron oxide nanoparticles (IONPs). This paper examined how the intravenous (IV) or intragastric (IG) route of administration influenced the intrahepatic distribution or therapeutic effects of IONPs. Wistar rats, some with bleeding-induced anemia, and iron oxide nanoparticles functionalized with salicylic acid (SaIONPs), with an average hydrodynamic diameter of 73 nm, compatible with rat sinusoid fenestrations, were used in this study. Light microscopy and multispectral camera analysis of Prussian blue labeled SaIONPs allowed mapping of intrahepatic nanoparticle deposits and revealed intrahepatic distribution patterns specific to each route of administration: loading of Kupffer cells and periportal hepatocytes when the IV route was used and predominant loading of hepatocytes when the IG route was used. Reducing the time to return to baseline values for hemoglobin (HGB) in rats with bleeding-induced anemia with IV or IG therapy has proven the therapeutic potential of SaIONPs in such anemias. The long-term follow-up showed that IV therapy resulted in higher HGB values. Proper use of the administration routes may modulate intrahepatic distribution and therapeutic effects of nanoparticles. These results may be beneficial in theragnosis of liver disease. [ABSTRACT FROM AUTHOR]

The incidence of liver fibrosis is increasing worldwide, and if left untreated, it will later develop into cirrhosis with a high mortality rate. In this paper, the activation pathway and related mechanism of stellate cells in liver fibrosis are introduced, and some current therapeutic methods are summarized. These results suggest that stellate cells play an important role in liver fibrosis, and targeted therapy for the purpose of inhibiting the activation of stellate cells and inducing their apoptosis is expected to be an effective regimen to reverse liver fibrosis. However, there are some problems such as insufficient in-depth study of related mechanisms and imperfect experiments. In future animal experiments and clinical trials, more studies can be carried out to provide high-quality protocols for the treatment of liver fibrosis. [ABSTRACT FROM AUTHOR]

Kupffer cells are liver resident macrophages and play critical role in fatty liver disease, yet the underlying mechanisms remain unclear. Here, we show that activation of G-protein coupled receptor 3 (GPR3) in Kupffer cells stimulates glycolysis and protects mice from obesity and fatty liver disease. GPR3 activation induces a rapid increase in glycolysis via formation of complexes between β-arrestin2 and key glycolytic enzymes as well as sustained increase in glycolysis through transcription of glycolytic genes. In mice, GPR3 activation in Kupffer cells results in enhanced glycolysis, reduced inflammation and inhibition of high-fat diet induced obesity and liver pathogenesis. In human fatty liver biopsies, GPR3 activation increases expression of glycolytic genes and reduces expression of inflammatory genes in a population of disease-associated macrophages. These findings identify GPR3 activation as a pivotal mechanism for metabolic reprogramming of Kupffer cells and as a potential approach for treating fatty liver disease. Whether Kupffer cells play a role in regulating the pathogenesis of fatty liver disease remains to be completely explored. Here, the authors show GPR3 activation stimulates glycolysis in Kupffer cells through GPR3-β-arrestin2-GAPDHPKM2 pathway and inhibits high-fat diet induced obesity and liver pathogenesis. [ABSTRACT FROM AUTHOR]

Salvianolic acid B (Sal B) is the primary water-soluble bioactive constituent derived from the roots of Salvia miltiorrhiza Bunge. This research was designed to reveal the potential mechanism of Sal B anti-liver injury from the perspective of macrophages. In our lipopolysaccharide-induced M1 macrophage model, Sal B showed a clear dose-dependent gradient of inhibition of the macrophage trend of the M1 type. Moreover, Sal B downregulated the expression of lactate dehydrogenase A (LDHA), while the overexpression of LDHA impaired Sal B's effect of inhibiting the trend of macrophage M1 polarization. Additionally, this study revealed that Sal B exhibited inhibitory effects on the lactylation process of histone H3 lysine 18 (H3K18la). In a ChIP-qPCR analysis, Sal B was observed to drive a reduction in H3K18la levels in the promoter region of the LDHA, NLRP3, and IL-1β genes. Furthermore, our in vivo experiments showed that Sal B has a good effect on alleviating CCl4-induced liver injury. An examination of liver tissues and the Kupffer cells isolated from those tissues proved that Sal B affects the M1 polarization of macrophages and the level of histone lactylation. Together, our data reveal that Sal B has a potential mechanism of inhibiting the histone lactylation of macrophages by downregulating the level of LDHA in the treatment of liver injury. [ABSTRACT FROM AUTHOR]

Background: As the largest substantive organ of animals, the liver plays an essential role in the physiological processes of digestive metabolism and immune defense. However, the cellular composition of the pig liver remains poorly understood. This investigation used single-nucleus RNA sequencing technology to identify cell types from liver tissues of pigs, providing a theoretical basis for further investigating liver cell types in pigs. Results: The analysis revealed 13 cells clusters which were further identified 7 cell types including endothelial cells, T cells, hepatocytes, Kupffer cells, stellate cells, B cells, and cholangiocytes. The dominant cell types were endothelial cells, T cells and hepatocytes in the liver tissue of Dahe pigs and Dahe black pigs, which accounts for about 85.76% and 82.74%, respectively. The number of endothelial cells was higher in the liver tissue of Dahe pigs compared to Dahe black pigs, while the opposite tendency was observed for T cells. Moreover, functional enrichment analysis demonstrated that the differentially expressed genes in pig hepatic endothelial cells were significantly enriched in the protein processing in endoplasmic reticulum, MAPK signaling pathway, and FoxO signaling pathway. Functional enrichment analysis demonstrated that the differentially expressed genes in pig hepatic T cells were significantly enriched in the thyroid hormone signaling pathway, B cell receptor signaling pathway, and focal adhesion. Functional enrichment analysis demonstrated that the differentially expressed genes in pig hepatic hepatocytes were significantly enriched in the metabolic pathways. Conclusions: In summary, this study provides a comprehensive cell atlas of porcine hepatic tissue. The number, gene expression level and functional characteristics of each cell type in pig liver tissue varied between breeds. [ABSTRACT FROM AUTHOR]

Hepatitis B virus (HBV) genotype C is a prevalent HBV genotype in the Chinese population. Although genotype C shows higher sequence heterogeneity and more severe liver disease than other genotypes, its pathogenesis and immunological traits are not yet fully elucidated. In this study, we first established and chemically synthesized the consensus sequence based on representative 138 full-length HBV genotype C genomes from the Chinese population. The pHBV1.3C plasmid system, containing a 1.3-fold full-length HBV genotype C consensus sequence, was constructed for subsequent validation. Next, we performed functional assays to investigate the replicative competence of pHBV1.3C in vitro through the transient transfection of HepG2 and Huh7 cells and validated the in vivo function via a hydrodynamic injection to BALB/c recipient mice. The in vitro investigation revealed that the extracellular HBV DNA and intracellular replicative intermediate (i.e., pregenomic RNA, pgRNA) were apparently measurable at 48 h, and the HBsAg and HBcAg were still positive in hepatoma cells at 96 h. We also found that HBsAg and HBeAg accumulated at the extracellular and intracellular levels in a time-dependent manner. The in vivo validation demonstrated that pHBV1.3C plasmids induced HBV viremia, triggered morphological changes and HBsAg- or HBcAg- positivity of hepatocytes, and ultimately caused inflammatory infiltration and focal or piecemeal necrosis in the livers of the murine recipients. HBV protein (HBsAg) colocalized with CD8+ T cells or CD4+ T cells in the liver. F4/80+ Kupffer cells were abundantly recruited around the altered murine hepatocytes. Taken together, our results indicate that the synthetic consensus sequence of HBV genotype C is replication-competent in vitro and in vivo. This genotype C consensus genome supports the full HBV life cycle, which is conducive to studying its pathogenesis and immune response, screening novel antiviral agents, and further optimizing testing and therapeutics. [ABSTRACT FROM AUTHOR]