Alternative activation of macrophages by prostacyclin synthase ameliorates alcohol induced liver injury

Cell-to-cell and organ-to-organ crosstalk in the pathogenesis of alcohol-associated liver disease

Alcohol-associated liver disease (ALD) is a growing global health concern and its prevalence and severity are increasing steadily. While bacterial endotoxin translocation into the portal circulation is a well-established key factor, recent evidence highlights the critical role of sterile inflammation, triggered by diverse stimuli, in alcohol-induced liver injury. This review provides a comprehensive analysis of the complex interactions within the hepatic microenvironment in ALD. It examines the contributions of both parenchymal cells, like hepatocytes, and non-parenchymal cells, such as hepatic stellate cells, Kupffer cells, neutrophils, and liver sinusoidal endothelial cells, in driving the progression of the disease. Additionally, we explored the involvement of key mediators, including cytokines, chemokines and inflammasomes, which regulate inflammatory responses and promote liver injury and fibrosis. A particular focus has been placed on extracellular vesicles (EVs) as essential mediators of intercellular communication both within and beyond the liver. These vesicles facilitate the transfer of signalling molecules, such as microRNAs and proteins, which modulate immune responses, fibrogenesis and lipid metabolism, thereby influencing disease progression. Moreover, we underscore the importance of organ-to-organ crosstalk, particularly in the gut-liver axis, where dysbiosis and increased intestinal permeability lead to microbial translocation, exacerbating hepatic inflammation. The adipose-liver axis is also highlighted, particularly the impact of adipokines and free fatty acids from adipose tissue on hepatic steatosis and inflammation in the context of alcohol consumption.

Emerging role of liver-bone axis in osteoporosis

Background

Increasing attention to liver-bone crosstalk has spurred interest in targeted interventions for various forms of osteoporosis. Liver injury induced by different liver diseases can cause an imbalance in bone metabolism, indicating a novel regulatory paradigm between the liver and bone. However, the role of the liver-bone axis in both primary and secondary osteoporosis remains inadequately elucidated. Therefore, exploring the exact regulatory mechanisms of the liver-bone axis may offer innovative clinical approaches for treating diseases associated with the liver and bone.

Methods

Here, we summarize the latest research on the liver-bone axis by searching the PubMed and Web of Science databases and discuss the possible mechanism of the liver-bone axis in different types of osteoporosis. The literature directly reporting the regulatory role of the liver-bone axis in different types of osteoporosis from the PubMed and Web of Science databases has been included in the discussion of this review (including but not limited to the definition of the liver-bone axis, clinical studies, and basic research). In addition, articles discussing changes in bone metabolism caused by different etiologies of liver injury have also been included in the discussion of this review (including but not limited to clinical studies and basic research).

Results

Several endocrine factors (IGF-1, FGF21, hepcidin, vitamin D, osteocalcin, OPN, LCAT, Fetuin-A, PGs, BMP2/9, IL-1/6/17, and TNF-α) and key genes (SIRT2, ABCB4, ALDH2, TFR2, SPTBN1, ZNF687 and SREBP2) might be involved in the regulation of the liver-bone axis. In addition to the classic metabolic pathways involved in inflammation and oxidative stress, iron metabolism, cholesterol metabolism, lipid metabolism and immunometabolism mediated by the liver-bone axis require more research to elucidate the regulatory mechanisms involved in osteoporosis.

Conclusion

During primary and secondary osteoporosis, the liver-bone axis is responsible for liver and bone homeostasis via several hepatokines and osteokines as well as biochemical signaling. Combining multiomics technology and data mining technology could further advance our understanding of the liver-bone axis, providing new clinical strategies for managing liver and bone-related diseases.The translational potential of this article is as follows: Abnormal metabolism in the liver could seriously affect the metabolic imbalance of bone. This review summarizes the indispensable role of several endocrine factors and biochemical signaling pathways involved in the liver-bone axis and emphasizes the important role of liver metabolic homeostasis in the pathogenesis of osteoporosis, which provides novel potential directions for the prevention, diagnosis, and treatment of liver and bone-related diseases.

Identification and validation of an endoplasmic-reticulum-stress-related gene signature as an effective diagnostic marker of endometriosis

Background

Endometriosis is one of the most common benign gynecological diseases and is characterized by chronic pain and infertility. Endoplasmic reticulum (ER) stress is a cellular adaptive response that plays a pivotal role in many cellular processes, including malignant transformation. However, whether ER stress is involved in endometriosis remains largely unknown. Here, we aimed to explore the potential role of ER stress in endometriosis, as well as its diagnostic value.

Methods

We retrieved data from the Gene Expression Omnibus (GEO) database. Data from the GSE7305 and GSE23339 datasets were integrated into a merged dataset as the training cohort. Differentially expressed ER stress-related genes (DEG-ERs) were identified by integrating ER stress-related gene profiles downloaded from the GeneCards database with differentially expressed genes (DEGs) in the training cohort. Next, an ER stress-related gene signature was identified using LASSO regression analysis. The receiver operating characteristic curve was used to evaluate the discriminatory ability of the constructed model, which was further validated in the GSE51981 and GSE105764 datasets. Online databases were used to explore the possible regulatory mechanisms of the genes in the signature. Meanwhile, the CIBERSORT algorithm and Pearson correlation test were applied to analyze the association between the gene signature and immune infiltration. Finally, expression levels of the signature genes were further detected in clinical specimens using qRT-PCR and validated in the Turku endometriosis database.

Results

In total, 48 DEG-ERs were identified in the training cohort. Based on LASSO regression analysis, an eight-gene-based ER stress-related gene signature was constructed. This signature exhibited excellent diagnostic value in predicting endometriosis. Further analysis indicated that this signature was associated with a compromised ER stress state. In total, 12 miRNAs and 23 lncRNAs were identified that potentially regulate the expression of ESR1, PTGIS, HMOX1, and RSAD2. In addition, the ER stress-related gene signature indicated an immunosuppressive state in endometriosis. Finally, all eight genes showed consistent expression trends in both clinical samples and the Turku database compared with the training dataset.

Conclusions

Our work not only provides new insights into the impact of ER stress in endometriosis but also provides a novel biomarker with high clinical value.

Recent insight into the role of macrophage in alcohol-associated liver disease: a mini-review

Alcohol-associated liver disease (ALD) is a condition that develops due to prolonged and excessive alcohol consumption. It encompasses various stages of liver damage, including fatty liver, alcoholic hepatitis, and cirrhosis. Immune cells, particularly macrophages, of various types play a significant role in the onset and progression of the disease. Macrophages observed in the liver exhibit diverse differentiation forms, and perform a range of functions. Beyond M1 and M2 macrophages, human macrophages can polarize into distinct phenotypes in response to various stimuli. Recent advancements have improved our understanding of macrophage diversity and their role in the progression of ALD. This mini-review provides a concise overview of the latest findings on the role and differentiation of macrophages in ALD. Additionally, it discusses potential therapeutic targets associated with macrophages and explores potential therapeutic strategies.

Serum exosomal m6A demethylase FTO promotes gefitinib resistance in non-small cell lung cancer by up-regulating FLRT3, PTGIS and SIRPα expression

This study investigates the molecular mechanism of FTO m6A demethylase in non-small cell lung cancer (NSCLC) and gefitinib resistance using GEO and TCGA databases. Differentially expressed genes (DEGs) were screened from RNA-seq data sets of serum exosomes of gefitinib-resistant NSCLC patients in the GEO database and the NSCLC data set in the GEPIA2 database. From this analysis, FTO m6A demethylase was found to be significantly upregulated in the serum exosomes of gefitinib-resistant NSCLC patients. To identify downstream genes affected by FTO m6A demethylase, weighted correlation network analysis and differential expression analysis were performed, resulting in the identification of three key downstream genes (FLRT3, PTGIS, and SIRPA). Using these genes, the authors constructed a prognostic risk assessment model. Patients with high-risk scores exhibited a significantly worse prognosis. The model could predict the prognosis of NSCLC with high accuracy measured by AUC values of 0.588, 0.608, and 0.603 at 1, 3, and 5 years respectively. Furthermore, m6A sites were found in FLRT3, PTGIS, and SIRPA genes, and FTO was significantly positively correlated with the expression of these downstream genes. Overall, FTO m6A demethylase promotes gefitinib resistance in NSCLC patients by upregulating downstream FLRT3, PTGIS, and SIRPA expression, with these three downstream genes serving as strong prognostic indicators.

Ambiguous Pathogenic Roles of Macrophages in Alcohol-Associated Liver Diseases

Alcohol-associated liver disease (ALD) represents a major public health issue worldwide and is a leading etiology of liver cirrhosis. Alcohol-related liver injuries include a range of manifestations including alcoholic hepatitis (AH), simple steatosis, steatohepatitis, hepatic fibrosis, cirrhosis and liver cancer. Liver disease occurs from several pathological disturbances such as the metabolism of ethanol, which generates reactive oxygen species (ROS) in hepatocytes, alterations in the gut microbiota, and the immune response to these changes. A common hallmark of these liver affections is the establishment of an inflammatory environment, and some (broad) anti-inflammatory approaches are used to treat AH (eg, corticosteroids). Macrophages, which represent the main innate immune cells in the liver, respond to a wide variety of (pathogenic) stimuli and adopt a large spectrum of phenotypes. This translates to a diversity of functions including pathogen and debris clearance, recruitment of other immune cells, activation of fibroblasts, or tissue repair. Thus, macrophage populations play a crucial role in the course of ALD, but the underlying mechanisms driving macrophage polarization and their functionality in ALD are complex. In this review, we explore the various populations of hepatic macrophages in alcohol-associated liver disease and the underlying mechanisms driving their polarization. Additionally, we summarize the crosstalk between hepatic macrophages and other hepatic cell types in ALD, in order to support the exploration of targeted therapeutics by modulating macrophage polarization.

Predominantly Pro-Inflammatory Phenotype with Mixed M1/M2 Polarization of Peripheral Blood Classical Monocytes and Monocyte-Derived Macrophages among Patients with Excessive Ethanol Intake

Excessive alcohol consumption impairs the immune system, induces oxidative stress, and triggers the activation of peripheral blood (PB) monocytes, thereby contributing to alcoholic liver disease (ALD). We analyzed the M1/M2 phenotypes of circulating classical monocytes and macrophage-derived monocytes (MDMs) in excessive alcohol drinkers (EADs). PB samples from 20 EADs and 22 healthy controls were collected for isolation of CD14+ monocytes and short-term culture with LPS/IFNγ, IL4/IL13, or without stimulation. These conditions were also used to polarize MDMs into M1, M2, or M0 phenotypes. Cytokine production was assessed in the blood and culture supernatants. M1/M2-related markers were analyzed using mRNA expression and surface marker detection. Additionally, the miRNA profile of CD14+ monocytes was analyzed. PB samples from EADs exhibited increased levels of pro-inflammatory cytokines. Following short-term culture, unstimulated blood samples from EADs showed higher levels of soluble TNF-α and IL-8, whereas monocytes expressed increased levels of surface TNF-α and elevated mRNA expression of pro-inflammatory cytokines and inducible nitric oxide synthase. MDMs from EADs showed higher levels of TNF-α and CD206 surface markers and increased IL-10 production. LPS/IFNγ induced higher mRNA expression of Nrf2 only in the controls. miRNA analysis revealed a distinctive miRNA profile that is potentially associated with liver carcinogenesis and ALD through inflammation and oxidative stress. This study confirms the predominantly pro-inflammatory profile of PB monocytes among EADs and suggests immune exhaustion features in MDMs.

Prostacyclin Released by Cancer-Associated Fibroblasts Promotes Immunosuppressive and Pro-Metastatic Macrophage Polarization in the Ovarian Cancer Microenvironment

Metastasis of high-grade ovarian carcinoma (HGSC) is orchestrated by soluble mediators of the tumor microenvironment. Here, we have used transcriptomic profiling to identify lipid-mediated signaling pathways encompassing 41 ligand-synthesizing enzymes and 23 cognate receptors in tumor, immune and stroma cells from HGSC metastases and ascites. Due to its strong association with a poor clinical outcome, prostacyclin (PGI₂) synthase (PTGIS) is of particular interest in this signaling network. PTGIS is highly expressed by cancer-associated fibroblasts (CAF), concomitant with elevated PGI₂ synthesis, whereas tumor-associated macrophages (TAM) exhibit the highest expression of its surface receptor (PTGIR). PTGIR activation by PGI₂ agonists triggered cAMP accumulation and induced a mixed-polarization macrophage phenotype with altered inflammatory gene expression, including CXCL10 and IL12A repression, as well as reduced phagocytic capability. Co-culture experiments provided further evidence for the interaction of CAF with macrophages via PGI₂, as the effect of PGI₂ agonists on phagocytosis was mitigated by cyclooxygenase inhibitors. Furthermore, conditioned medium from PGI₂-agonist-treated TAM promoted tumor adhesion to mesothelial cells and migration in a PTGIR-dependent manner, and PTGIR activation induced the expression of metastasis-associated and pro-angiogenic genes. Taken together, our study identifies a PGI₂/PTGIR-driven crosstalk between CAF, TAM and tumor cells, promoting immune suppression and a pro-metastatic environment.

Myc-mediated circular RNA circMcph1/miR-370-3p/Irak2 axis is a progressive regulator in hepatic fibrosis

AIMS

Treating hepatic fibrosis (HF) is a major challenge worldwide. However, the biological functions and regulatory mechanisms of circular RNAs (circRNAs) remain unclear in HF. The present study aimed to elucidate the novel role of circMcph1 in HF.

MAIN METHODS

HF mouse model was established by injecting CCl₄ intraperitoneally and validated using hematoxylin and eosin staining, immunohistochemistry, and serological tests in vivo. RAW264.7 cells were treated with lipopolysaccharide (LPS) and interferon-γ (IFN-γ) in vitro inflammatory damage model. Gel electrophoresis, DNA sequencing, RNase R and actinomycin D treatment, random 6 primers and oligo dT primers assay, nuclear and cytoplasmic fractionation assay, and fluorescence in situ hybridization were performed to identify the characteristics of circMcph1. Functional assays such as ELISA, flow cytometry, and adeno-associated virus administration in vivo and liposome delivery gene therapy in vitro were used to determine the functional effects of circMcph1/miR-370-3p/interleukin-1 receptor-associated kinase 2 (Irak2) axis. Mechanistic assays such as luciferase reporter analysis, and chromatin immunoprecipitation revealed the molecular mechanism of the Myc/circMcph1/miR-370-3p/Irak2 axis in HF.

KEY FINDINGS

CircMcph1 expression was upregulated in liver tissues and primary Kupffer cells of CCl₄-induced HF mice, as well as in LPS and IFN-γ-treated RAW264.7 cells. Knockdown of circMcph1 ameliorated liver fibrogenesis and inflammatory damage in HF mice and reduced the inflammatory response in LPS and IFN-γ-treated RAW264.7 cells. Mechanically, circMcph1 mediated by Myc regulated the expression of Irak2 by sponging miR-370-3p in HF.

SIGNIFICANCE

The study findings suggested that the Myc/circMcph1/miR-370-3p/Irak2 axis might be a novel identifier and therapeutic target for HF.

Metabolic and Proteomic Profiles Associated with Immune Responses Induced by Different Inactivated SARS-CoV-2 Vaccine Candidates

Since the emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in late 2019, the virus has been mutating continuously, resulting in the continuous emergence of variants and creating challenges for epidemic prevention and control. Here, we immunized mice with different vaccine candidates, revealing the immune, protein, and metabolomic changes that take place in vaccines composed of different variants. We found that the prototype strain and Delta- and Omicron-variant inactivated vaccine candidates could all induce a high level of neutralizing antibodies and cellular immunity responses in mice. Next, we found that the metabolic and protein profiles were changed, showing a positive association with immune responses, and the level of the change was distinct in different inactivated vaccines, indicating that amino acid variations could affect metabolomics and proteomics. Our findings reveal differences between vaccines at the metabolomic and proteomic levels. These insights provide a novel direction for the immune evaluation of vaccines and could be used to guide novel strategies for vaccine design.

Innate lymphocytes: Role in alcohol-induced immune dysfunction

Alcohol use is known to alter the function of both innate and adaptive immune cells, such as neutrophils, macrophages, B cells, and T cells. Immune dysfunction has been associated with alcohol-induced end-organ damage. The role of innate lymphocytes in alcohol-associated pathogenesis has become a focus of research, as liver-resident natural killer (NK) cells were found to play an important role in alcohol-associated liver damage pathogenesis. Innate lymphocytes play a critical role in immunity and homeostasis; they are necessary for an optimal host response against insults including infections and cancer. However, the role of innate lymphocytes, including NK cells, natural killer T (NKT) cells, mucosal associated invariant T (MAIT) cells, gamma delta T cells, and innate lymphoid cells (ILCs) type 1–3, remains ill-defined in the context of alcohol-induced end-organ damage. Innate-like B lymphocytes including marginal zone B cells and B-1 cells have also been identified; however, this review will address the effects of alcohol misuse on innate T lymphocytes, as well as the consequences of innate T-lymphocyte dysfunction on alcohol-induced tissue damage.

Hypoxia-hindered methylation of PTGIS in endometrial stromal cells accelerates endometriosis progression by inducing CD16- NK-cell differentiation

Prostacyclin (PGI₂) plays key roles in shaping the immune microenvironment and modulating vasodilation, whereas its contribution to endometriosis (EMs) remains largely unclear. Our study suggested that prostacyclin synthase (PTGIS)-dependent PGI₂ signaling was significantly activated in EMs, which was involved in the hypoxic microenvironment of ectopic lesions and deficient methylation status of the PTGIS promoter. Notably, in vitro assays, hypoxia promoted PTGIS expression through DNA methyltransferase 1 (DNMT1)-mediated DNA methylation deficiency in endometrial stromal cells (ESCs); PTGIS overexpression enhanced the adhesive ability of ESCs and led to elevated PGI₂ production, and PGI₂ triggered CD16⁻ (encoded by FCGR3, Fc fragment of IgG receptor IIIa) natural killer (NK)-cell differentiation through PGI₂ receptor (IP, PTGIR) in an ESC/NK-cell coculture system. Our rodent model experiment suggested that treatment with the PGI₂ analog iloprost and adoptive transfer of fcgr3 knockout (fcgr3^−/−) NK cells aggravated EMs progression and that genetic ablation of ptgis (ptgis^−/−) in ectopic lesions and treatment with the PTGIR antagonist RO1138452 partially rescued this outcome. Thus, our findings identified the contribution of PGI₂ to EMs progression via enhancement of the adhesive ability of ESCs and inhibition of the activity of NK cells. We hypothesized that PGI₂ is a target for EMs intervention and provide a rationale for studying pharmacological PTGIR inhibition and PTGIS genetic depletion therapies as therapeutic strategies for EMs.

Inhibiting the activity of a critical enzyme found overexpressed in endometriosis lesions could lead to novel therapeutics. Endometriosis affects around 10 per cent of women of reproductive age globally, yet the condition is poorly understood. Endometriosis lesions are known to be in a hypoxic, or low oxygen, state. Zhao Dong at Tongji University in Shanghai, China, and co-workers used human tissue samples and mouse models to determine the roles of a metabolite called prostacyclin (PGI₂) and its catalytic enzyme (prostacyclin synthase, PTGIS) in endometriosis. PTGIS levels were significantly elevated in hypoxic endometrial cells, triggering the overproduction of PGI₂. This PTGIS/PGI₂ increase enhanced the adhesiveness of the cells, promoting survival of developing lesions. PGI₂ overproduction also triggered abnormal differentiation of a specific group of immune cells called natural killer cells, disrupting the body’s immune response.

A novel prostaglandin I2 agonist, ONO-1301, attenuates liver inflammation and suppresses fibrosis in non-alcoholic steatohepatitis model mice

BACKGROUND

ONO-1301 is a novel long-lasting prostaglandin (PG) I₂ mimetic with inhibitory activity on thromboxane (TX) A₂ synthase. This drug can also induce endogenous prostaglandin (PG)I2 and PGE2 levels. Furthermore, ONO-1301 acts as a cytokine inducer and can initiate tissue repair in a variety of diseases, such as pulmonary hypertension, pulmonary fibrosis, cardiac infarction, and obstructive nephropathy. In this study, our aim was to evaluate the effect of ONO-1301 on liver inflammation and fibrosis in a mouse model of non-alcoholic steatohepatitis (NASH).

METHODS

The therapeutic effects of ONO-1301 against liver damage, fibrosis, and occurrence of liver tumors were evaluated using melanocortin 4 receptor-deficient (Mc4r-KO) NASH model mice. The effects of ONO-1301 against macrophages, hepatic stellate cells, and endothelial cells were also evaluated in vitro.

RESULTS

ONO-1301 ameliorated liver damage and fibrosis progression, was effective regardless of NASH status, and suppressed the occurrence of liver tumors in Mc4r-KO NASH model mice. In the in vitro study, ONO-1301 suppressed LPS-induced inflammatory responses in cultured macrophages, suppressed hepatic stellate cell (HSC) activation, upregulated vascular endothelial growth factor (VEGF) expression in HSCs, and upregulated hepatocyte growth factor (HGF) and VEGF expression in endothelial cells.

CONCLUSIONS

The results of our study highlight the potential of ONO-1301 to reverse the progression and prevent the occurrence of liver tumors in NASH using in vivo and in vitro models. ONO-1301 is a multidirectional drug that can play a key role in various pathways and can be further analyzed for use as a new drug candidate against NASH.