Hepatic recruitment of eosinophils and their protective function during acute liver injury

Myeloid-specific deficiency of group VIA calcium-independent phospholipase A2 preconditions myeloid cells for injury resolution after acetaminophen exposure

Genetic PLA2G6 variants are associated with C-reactive protein in humans. Myeloid-specific PLA2G6-deficient (Pla2g6M-/-) mice show increased hepatic myeloperoxidase and recruitment of granulocytes in response to lipopolysaccharide (LPS). We hypothesized that Pla2g6M-/- mice could be protected from acetaminophen (APAP) hepatotoxicity whereby neutrophils, eosinophils, and alternatively activated macrophages are reportedly protective. Herein, Pla2g6M-/- mice treated with 300 mg/kg APAP for 24 h showed attenuated hepatic necrosis and plasma cytokines, and with elevated levels of Ly6Clo in peripheral blood mononuclear cells and plasma lipoxin A4. Remarkably, bone-marrow-derived macrophages (BMDMs) from untreated Pla2g6M-/- mice exhibited elevated baseline expression of cPLA2α, NOX2, Rac1, Arg-1, phospho-MLKL, and iNOS protein, which was exacerbated by LPS in vitro. APAP administration preconditioned Pla2g6M-/- BMDMs for further activation of enzymes involving in phagocytosis (Rac1 and phospho-MLKL) and eicosanoids (COX2 and A15LOXB). Pla2g6M-/- BMDMs showed an increased release of pro-resolution lipid mediators lipoxin A4, PGE2, and 15d-PGJ2, which was further elevated by LPS in vitro or APAP in vivo. Phagocytic gene signatures (myeloperoxidase and NOX2) were also upregulated in livers of untreated and APAP-treated Pla2g6M-/- mice. APAP protection in Pla2g6M-/- mice was associated with increased proportion of neutrophils (Ly6G), eosinophils (eosinophilic cationic protein), and M2 macrophages (CD206) in/at the portal tract and central vein as determined by immunohistochemistry. Thus, myeloid-specific PLA2G6 deficiency preconditioned macrophages for eicosanoid and phagocytic pathways rendering protection against APAP hepatotoxicity. Our results may be applicable to patients with PLA2G6 mutations, and PLA2G6 inhibition specifically in myeloid cells may represent a new strategy to alleviate APAP poisoning.

The protective effects of propolis against lipopolysaccharide-induced acute liver injury by modulating serum metabolites and gut flora

Propolis has significant hepatoprotective effects, but the active components, targets, and mechanisms have not been fully elucidated. Here, we integrated network pharmacology, serum metabolomics, and 16 S rRNA sequencing to disclose the hepatoprotective effects of Chinese propolis (CP) by lipopolysaccharide (LPS)-induced acute liver injury (ALI) in mice. The core active ingredients of CP against ALI, including quercetin, luteolin, and kaempferol, can bind stably to pro-inflammatory factors such as TNF-α, IL-6, IL-1β, and IFN-γ. CP and its active ingredient quercetin obviously alleviated LPS-induced ALI in mice and downregulated the levels of pro-inflammatory genes (Tnf-α, Il-1β, Il-6, Mcp-1, Ifn-γ, and Cox-2) while increasing the protein expression levels of the antioxidant factors Nrf2 and HO-1. Untargeted serum metabolomics analysis indicated that CP and quercetin ameliorated LPS-induced metabolic disorders mainly by modulating the ascorbate and aldarate metabolisms. 16 S rRNA sequencing demonstrated that CP and quercetin modulated the gut microbiota, augmenting the relative abundance of anti-inflammatory bacteria like Lactobacillus and Dubosiella and diminishing the pro-inflammatory bacteria like Alistipes. Spearman correlation analysis revealed that there existed significant correlations among inflammatory factors, gut microbiota, and differential metabolites of serum after propolis pretreatment. Our research indicated that propolis effectively alleviated pathological damage in LPS-induced ALI mice mainly through partially restoring the ecology of gut flora and metabolic disorders to reduce inflammation.

Emerging Roles of C-C Motif Ligand 11 (CCL11) in Cancers and Liver Diseases: Mechanisms and Therapeutic Implications

C-C motif ligand 11 (CCL11) is a multifunctional chemokine that regulates immunity, angiogenesis, and tissue remodeling. In addition to its allergic inflammation role, CCL11 exhibits context-dependent dual functions in relation to cancer progression. In liver diseases, it mediates injury, fibrosis, and inflammation while serving as a disease biomarker. This review systematically examines CCL11-receptor interactions and their immunomodulatory mechanisms in cancers and hepatic pathologies. We highlight CCL11's therapeutic potential as both a prognostic marker and immunotherapeutic target. By integrating molecular and clinical insights, this work advances the understanding of CCL11's pathophysiological roles and facilitates targeted therapy development.

Liver failure diagnosis: key diagnostic biomarkers discovery and bioinformatic validation

Background

Glutathione peroxidase 3 (GPX3) is a strong antioxidant. While elevated GPX3 levels are linked to diverse pathologies, its role in liver failure (LF) remains underexplored. This study investigates GPX3's diagnostic potential and mechanistic contributions to LF pathogenesis.

Methods

We integrated two high-quality liver tissue datasets (GSE38941 and GSE14668) from the Gene Expression Omnibus (GEO) database. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses were conducted to identify potential biomarkers associated with liver failure. The Comparative Toxicogenomics Database was used to predict the function of GPX3. In addition, in our study, we verified the target gene mRNA expression level in 40 patients with acute or chronic acute liver failure (ACHBLF) by RT-QCPR experiment and detect the methylation status of GPX3 promoter of ACHBLF patients with methylation specific PCR (MSP).

Results

The results demonstrate that GPX3 drives pathogenic mechanisms in liver failure through oxidative stress-related pathways (e.g., collagen cross-linking, extracellular matrix remodeling) and immune dysregulation (e.g., macrophage activation, PD-1/CTLA-4 signaling). CPX8, PRDX6, GPX4, GSS, GSR, TXN, GPX7, PPARGC1A, ALOX15, and ALOX5 have been identified as key immune-related genes. Furthermore, there were significant differences in immune cell infiltration between the high and low expression groups of GPX3 groups. Immune infiltration analysis demonstrated strong correlations between GPX3 expression and key immune markers (p < 0.05), suggesting its role in modulating inflammatory responses. Additionally, GPX3 increased susceptibility to aerosols, cyclosporin and dexamethasone was observed in patients with elevated levels of GPX3. The mRNA expression of GPX3 was much higher in ACHBLF patients than in other groups. In ACHBLF patients, the group with GPX3 methylated promoter had higher mortality than those without.

Conclusion

In conclusion, GPX3 is a promising diagnostic biomarker for liver failure. Its promoter methylation status may serve as a prognostic indicator, highlighting its therapeutic potential.

DIA-based quantitative proteomics explores the mechanism of amelioration of APAP-induced liver injury by anoectochilus roxburghii (Wall.) Lindl

Background

Drug-induced liver injury (DILI) is the most common cause of acute liver injury. Anoectochilus roxburghii (Wall.) Lindl. (AR) and its polysaccharide fractions (ARPs) have been shown to have effective therapeutic effects with minimal side effects on a wide range of diseases including hepatopathy. This study aims to determine the therapeutic effects of ARPs on acetaminophen (APAP)-induced liver injury and to explore the mechanistic pathways involved.

Methods

C57BL/6J male mice at 8 weeks were used to construct a model of APAP-induced liver injury. The acute hepatic injury was induced by oral administration of APAP (300 mg/kg) before 16 h fasting. For therapeutic experiment, mice were gavaged with the water extract of AR (AR.WE) or the purified ARPs before and after APAP administration. Biochemical analyses, ELISA analyses, H&E staining, RT-PCR, and Quantitative proteomic analysis were used to investigate the effects and mechanisms of AR on DILI.

Results

Both AR.WE. and the purified ARPs treatment reduced APAP-induced liver injury, decreased hepatic glutathione and TNF-α levels, alleviated oxidative stress and inflammation. Quantitative proteomic analysis revealed that ARPs downregulated the protein levels involved in apoptosis, inflammation, oxidative stress, necroptosis, while upregulated the protein levels involved in autophagy. These protective effects of ARPs are possibly related to the downregulation of vATPase activity and thus participating in the autophagic process and ferroptosis.

Conclusion

ARPs can protect mice against APAP-induced liver injury, alleviate oxidative stress and inflammation. Our study reveals a potential therapeutic effect for ARPs in protecting APAP-induced liver injury.

Alleviation effect of macrophage depletion on hepatotoxicity of triptolide: A new insight based on metabolomics and proteomics

ETHNOPHARMACOLOGICAL RELEVANCE

Triptolide (TP) is an abietane-type diterpenoid isolated from the traditional Chinese herb Tripterygium wilfordii Hook. F, which is used to relieve rheumatism, alleviate joint pain and swelling, and promote blood circulation for more than 600 years in China. The most common preparations containing TP from Tripterygium wilfordii Hook F, which are Tripterygium tablets and Tripterygium glycoside tablets, are widely used in clinical for treating rheumatoid arthritis and other autoimmune diseases at present. However, the clinical application is hindered by severe systemic toxicity induced by TP, especially hepatotoxicity. It is crucial to discover potent and specific detoxification strategy for TP.

AIM OF STUDY

According to our previous study, TP-induced hepatotoxicity is primarily related to macrophages. This study aimed to investigate the alleviation effects of macrophage depletion on the TP-induced liver injury in mice and to explore the related mechanisms by integration of metabolomics and proteomics.

MATERIALS AND METHODS

Mice were treated with clodronate liposomes to deplete macrophage before administration of triptolide. The alleviation effects were evaluated by biochemical analysis of serum and histopathology observation of the hepatic tissues. Metabolomics and proteomics were carried out to explore the mechanism of macrophage depletion on triptolide-induced liver injury. The levels of mRNA and protein of TLR4- MyD88-NF-κB axis were further detected.

RESULTS

The altered levels of biochemistry indicators, including aminotransferase (ALT) and aspartate aminotransferase (AST), albumin (ALB), and γ-glutamyltranspeptidase (GGT) were significantly recovered, and histopathological liver injury also showed restoring tendency in mice with macrophage depletion compared to mice with TP-treatment. The inflammation indicator interleukin-6 (IL-6) and interleukin-1β (IL-1β) were recovered significantly after depletion of macrophage. Results of metabolomics and proteomics demonstrated that macrophage depletion exerted protective effects on triptolide-induced liver injury by regulating 85 metabolites and 202 proteins. Joint analysis of multi-omics data suggested macrophage depletion could regulate lipid metabolism and maintain inflammatory homeostasis. The increased expression of NF-κB, TLR4, and MyD88 were decreased after depletion of macrophage.

CONCLUSION

TP-induced hepatotoxicity is mainly associated with dysfunction of macrophages and imbalance of inflammatory homeostasis. The findings of this study may help facilitate the development of novel therapeutic strategies.

Chenodeoxycholic acid modulates cholestatic niche through FXR/Myc/P-selectin axis in liver endothelial cells

Cholestatic liver diseases are characterized by excessive bile acid accumulation in the liver. Endothelial cells (ECs) shape the local microenvironment in both normal conditions and liver injury, yet their role in cholestasis is unclear. Through a comparative analysis of single-cell RNA sequencing data from various murine models of liver injury, we identify distinctive Myc activation within ECs during obstructive cholestasis resulting from bile duct ligation (BDL). Myc overexpression in ECs significantly upregulates P-selectin, increasing neutrophil infiltration and worsening cholestatic liver injury. This process occurs through the FXR, activated by chenodeoxycholic acid (CDCA) and its conjugate TCDCA. Inhibiting P-selectin with PSI-697 reduces neutrophil recruitment and alleviates injury. Cholestatic patient liver samples also show elevated Myc and P-selectin in ECs, along with increased neutrophils. The findings identify ECs as key drivers of cholestatic liver injury through a Myc-driven program and suggest that targeting the CDCA/FXR/Myc/P-selectin axis may offer a therapeutic approach.

A new human autologous hepatocyte/macrophage co-culture system that mimics drug-induced liver injury-like inflammation

The development of in vitro hepatocyte cell culture systems is crucial for investigating drug-induced liver injury (DILI). One prerequisite for monitoring DILI related immunologic reactions is the extension of primary human hepatocyte (PHH) cultures towards the inclusion of macrophages. Therefore, we developed and characterized an autologous co-culture system of PHH and primary human hepatic macrophages (hepM) (CoC1). We compared CoC1 with a co-culture of the same PHH batch + M0 macrophages derived from THP1 cells (CoC2) in order to represent a donor independent macrophage reaction. Then, we treated the mono- and co-cultures with drugs that cause DILI-menadione (MEN, 1 or 10 µM, 3 h), diclofenac (DIC, 0.5 or 5 mM, 6 h), or acetaminophen (APAP, 0.5 or 5 mM, 6 h)-and assessed culture stability, cell activity, macrophage differentiation, cytokine production and cell viability. Without drug treatment, CoC1 was the most stable over a culture time of up to 60 h. Cytokine array analysis revealed a proinflammatory profile of PHH mono-cultures due to isolation stress but showed different influences of hepM and M0 on the cytokine profile in the co-cultures. MEN, DIC and APAP treatment led to donor-dependent signs of cell stress and toxicity. HepM can either promote or reduce the DILI effects donor dependently in CoC1. CoC2 are slightly less sensitive than CoC1 in representing DILI. In summary, we present a new autologous co-culture system that can mimic DILI in a donor-dependent manner. This cellular system could be useful for new drug testing strategies and reducing animal testing.

Eosinophils Respond to Extracellular Matrix Treated Muscle Injuries but are Not Required for Macrophage Polarization

The immune response to decellularized extracellular matrix (ECM) muscle injury is characterized by Th2 T cells, Tregs, M2-like macrophages, and an abundance of eosinophils. Eosinophils have previously been described as mediators of muscle regeneration but inhibit skin wound healing. In addition to response to wounding, a large number of eosinophils respond to biomaterial-treated muscle injury, specifically in response to decellularized ECM. ECM treatment of muscle wounds has been associated with positive outcomes in tissue regeneration, but the detailed mechanisms of action are still being evaluated. Here, this work investigates the role of these eosinophils in terms of their immunologic phenotype and subsequent effect on the local tissue microenvironment. These cells have a mixed phenotype showing both type-2 and regulatory gene upregulation and but are not required for macrophage polarization. Beyond the local tissue, ECM treatment is seen to induce a transient flux of eosinophils to the lungs but prevented a trauma-associated neutrophilia in the lungs of injured mice. This work believes this local and systemic immunomodulation contributes to the regenerative effects of the material and such distal tissue effects should be considered in therapeutic design and implementation.

Dynamic analysis of intrahepatic T cells reveals a unique group of restorative Cxcr3+ tissue-resident CD4 T cells in acute liver injury

Acetaminophen (APAP) stands as one of the most prevalent triggers of drug-induced acute liver injury (ALI). The intricate modulation of immune system activation and inflammatory cascades by hepatic immune cells is paramount in managing liver injury and subsequent restoration. In this study, we employed an integrative approach that fused our proprietary flow cytometry analyses across various time points post-APAP injury with publicly available single-cell RNA sequencing (scRNA-seq) datasets, encompassing time-series data from liver tissue of mice subjected to APAP intoxication. This allowed us to delve into the dynamics of T cell profiles during APAP-induced ALI. Our comprehensive analyses unveiled the intricate temporal shifts in intrahepatic T cell populations across different phases following APAP-induced ALI. Notably, we observed a persistent augmentation of intrahepatic CD4+ T cells post-APAP injury. Amongst these, a distinct population of restorative Cxcr3+ tissue-resident CD4+ T cells emerged. Inhibition of CXCR3 using a neutralizing antibody exacerbated APAP-induced liver function impairment and hepatocyte death. Furthermore, we identified that the Cxcr3+ tissue-resident CD4+ T cells were tightly regulated by intrahepatic ''Lgals9-Cd45'' and 'CXCL13-Cxcr3' signaling pathways. These discoveries underscore the novel protective function of CXCR3, a vital biological macromolecule, in mitigating APAP-induced ALI, and may shed lights on new therapeutic strategies targeting this condition.

Eosinophils Enhance Granuloma-Mediated Control of Persistent Salmonella Infection

Salmonella enterica can persist asymptomatically within tissues for extended periods. This remarkable feat is achieved through intricate host-pathogen interactions in immune cell aggregates called granulomas, wherein Salmonella find favorable cellular niches to exploit while the host limits its expansion and tissue dissemination. Here, using a mouse model of persistent Salmonella infection, we identify a host-protective role of eosinophils in control of Salmonella Typhimurium (STm) infection within the mesenteric lymph nodes (MLN), the main lymphoid tissue of STm persistence. Combining spatial transcriptomics and experimental manipulations, we found that macrophages responding to STm infection recruited eosinophils in a C-C motif chemokine ligand 11 (CCL11)-dependent manner and enhanced their activation. Eosinophil deficiencies increased Salmonella burdens, which was associated with altered granuloma size and impaired type-1 immunity in the MLN. Thus, eosinophils play a vital role in restraining Salmonella exploitation of granuloma macrophages at a key site of bacterial persistence.

Innate immune regulation in inflammation resolution and liver regeneration in drug-induced liver injury

Drug-induced liver injury (DILI) is an acute liver injury that poses a significant threat to human health. In severe cases, it can progress into chronic DILI or even lead to liver failure. DILI is typically caused by either intrinsic hepatotoxicity or idiosyncratic metabolic or immune responses. In addition to the direct damage drugs inflict on hepatocytes, the immune responses and liver inflammation triggered by hepatocyte death can further exacerbate DILI. Initially, we briefly discussed the differences in immune cell activation based on the type of liver cell death (hepatocytes, cholangiocytes, and LSECs). We then focused on the role of various immune cells (including macrophages, monocytes, neutrophils, dendritic cells, liver sinusoidal endothelial cells, eosinophils, natural killer cells, and natural killer T cells) in both the liver injury and liver regeneration stages of DILI. This article primarily reviews the role of innate immune regulation mediated by these immune cells in resolving inflammation and promoting liver regeneration during DILI, as well as therapeutic approaches targeting these immune cells for the treatment of DILI. Finally, we discussed the activation and function of liver progenitor cells (LPCs) during APAP-induced massive hepatic necrosis and the involvement of chronic inflammation in DILI.

Targeting PPARα/γ by icariside II to rescue GalN/LPS-induced acute liver injury in mice: Involvement of SIRT6/NF-κB signaling pathway

BACKGROUND

Peroxisome proliferator-activated receptor α and-γ (PPARα/γ) are known to play crucial roles in acute liver injury (ALI). Icariside II (ICS II), a natural flavonoid compound derived from Herba EpimedII, confers neuroprotection with PPARα/γ induction potency.

PURPOSE

This study was aimed to explore whether ICS II has the capacity to protect against ALI, and the role of PPARα/γ in the beneficial effect of ICS II on ALI.

METHODS

Mice challenged by D-galactosamine (GalN)/lipopolysaccharide (LPS) and Kupffer cells (KCs) upon LPS insult were used as ALI models in vivo and in vitro. PPARα/γ-deficient mice were treated with ICS II to validate the potential targets of ICS II on ALI.

RESULTS

We found that ICS II (5, 10, 20 mg/kg) dose-dependently improved the survival rate and liver histology, decreased ALT and AST in GalN/LPS-treated mice. Furthermore, ICS II directly bound to PPARα/γ and increased their activities. The protective properties of ICS II were counteracted when PPARα/γ were knocked out in GalN/LPS-induced mice and LPS-induced KCs, respectively. Mechanistically, ICS II restored mitochondrial function, reduced oxidative stress and inflammation through activating PPARα/γ, which activated Sirt6 and inhibited NF-κB nuclear translocation.

CONCLUSION

Our findings not only highlight PPARα/γ-SIRT6 signaling as a vital therapeutic target to combat ALI, but also reveal ICS II may serve as a novel dual PPARα/γ agonist to safeguard ALI from the oxidation-inflammation vicious circle by mediating SIRT6/NF-κB.

Circadian system disorder induced by aberrantly activated EFNB2-EPHB2 axis leads to facilitated liver metastasis in gastric cancer

BACKGROUND

Liver is one of the most preferred destinations for distant metastasis of gastric cancer (GC) and liver metastasis usually predicts poor prognosis. The achievement of liver metastasis requires continued cross-talk of complex members in tumor microenvironment (TME) including tumor associated macrophages (TAMs).

METHODS

Results from 35 cases of ex vivo cultured living tissues of GC liver metastasis have elucidated that circadian rhythm disorder (CRD) of key molecules involved in circadian timing system (CTS) facilitates niche outgrowth. We next analyzed 69 cases of liver metastasis from patients bearing GC and designed co-culture or 3D cell culture, discovering that TAMs expressing EFNB2 could interact with tumor cell expressing EPHB2 for forward downstream signaling and lead to CRD of tumor cells. Moreover, we performed intrasplenic injection models assessed by CT combined 3D organ reconstruction bioluminescence imaging to study liver metastasis and utilized the clodronate treatment, bone marrow transplantation or EPH inhibitor for in vivo study followed by exploring the clinical therapeutic value of which in patient derived xenograft (PDX) mouse model.

RESULTS

Ex vivo studies demonstrated that CRD of key CTS molecules facilitates niche outgrowth in liver metastases. In vitro studies revealed that TAMs expressing EFNB2 interact with tumor cells expressing EPHB2, leading to CRD and downstream signaling activation. The underlying mechanism is the enhancement of the Warburg effect in metastatic niches.

CONCLUSION

Overall, we aim to uncover the mechanism in TAMs induced CRD which promotes liver metastasis of GC and provide novel ideas for therapeutic strategies.

Spatial adaptation of eosinophils and their emerging roles in homeostasis, infection and disease

Eosinophils are bone marrow-derived granulocytes that are traditionally associated with type 2 immune responses, such as those that occur during parasite infections and allergy. Emerging evidence demonstrates the remarkable functional plasticity of this elusive cell type and its pleiotropic functions in diverse settings. Eosinophils broadly contribute to tissue homeostasis, host defence and immune regulation, predominantly at mucosal sites. The scope of their activities primarily reflects the breadth of their portfolio of secreted mediators, which range from cytotoxic cationic proteins and reactive oxygen species to multiple cytokines, chemokines and lipid mediators. Here, we comprehensively review basic eosinophil biology that is directly related to their activities in homeostasis, protective immunity, regeneration and cancer. We examine how dysregulation of these functions contributes to the physiopathology of a broad range of inflammatory diseases. Furthermore, we discuss recent findings regarding the tissue compartmentalization and adaptation of eosinophils, shedding light on the factors that likely drive their functional diversification within tissues.

Exploring Cuproptosis-Related Genes and Diagnostic Models in Renal Ischemia-Reperfusion Injury Using Bioinformatics, Machine Learning, and Experimental Validation

Background

Renal ischemia-reperfusion injury (RIRI) is a significant cause of acute kidney injury, complicating clinical interventions such as kidney transplants and partial nephrectomy. Recent research has indicated the role of cuproptosis, a copper-dependent cell death pathway, in various pathologies, but its specific involvement in RIRI remains insufficiently understood. This study aims to investigate the role of cuproptosis-related genes in RIRI and establish robust diagnostic models.

Methods

We analyzed transcriptomic data from 203 RIRI and 188 control samples using bioinformatics tools to identify cuproptosis-related differentially expressed genes (CRDEGs). The relationship between CRDEGs and immune cells was explored using immune infiltration analysis and correlation analysis. Gene Set Enrichment Analysis (GSEA) was conducted to identify pathways associated with CRDEGs. Machine learning models, including Least Absolute Shrinkage and Selection Operator(LASSO) logistic regression, Support Vector Machine Recursive Feature Elimination (SVM-RFE), Clustering analysis, and weighted gene co-expression network analysis (WGCNA), were used to construct diagnostic gene models. The models were validated using independent datasets. Experimental validation was conducted in vivo using a mouse bilateral RIRI model and in vitro using an HK-2 cell hypoxia-reoxygenation (HR) model with copper chelation intervention. HE, PAS, and TUNEL staining, along with plasma creatinine and blood urea nitrogen (BUN) measurements, were used to evaluate the protective effect of the copper chelator D-Penicillamine (D-PCA) on RIRI in mice. JC-1 and TUNEL staining were employed to assess apoptosis in HK-2 cells under hypoxia-reoxygenation conditions. Immunofluorescence and Western blot (WB) techniques were used to verify the expression levels of the SDHB and NDUFB6 genes.

Results

A total of 18 CRDEGs were identified, many of which were significantly correlated with immune cell infiltration. GSEA revealed that these genes were involved in pathways related to oxidative phosphorylation and immune response regulation. Four key cuproptosis marker genes (LIPA, LIPT1, SDHB, and NDUFB6) were incorporated into a Cuproptosis Marker Gene Model(CMGM), achieving an area under the curve (AUC) of 0.741-0.834 in validation datasets. In addition, a five-hub-gene SVM model (MOAP1, PPP2CA, SYL2, ZZZ3, and SFRS2) was developed, demonstrating promising diagnostic performance. Clustering analysis revealed two RIRI subtypes (C1 and C2) with distinct molecular profiles and pathway activities, particularly in oxidative phosphorylation and immune responses. Experimental results showed that copper chelation alleviated renal damage and cuproptosis in both in vivo and in vitro models.

Conclusion

Our study reveals that cuproptosis-related genes are significantly involved in RIRI, particularly influencing mitochondrial dysfunction and immune responses. The diagnostic models developed showed promising predictive performance across independent datasets. Copper chelation demonstrated potential therapeutic effects, suggesting that cuproptosis regulation may be a viable therapeutic strategy for RIRI. This work provides a foundation for further exploration of copper metabolism in renal injury contexts.

The Role of Eosinophils in Liver Disease

Previously, eosinophils were primarily regarded as effector toxic cells involved in allergic diseases and parasitic infections. Nevertheless, new research has shown that eosinophils are diverse and essential for immune regulation and tissue homeostasis. Their functional plasticity has been observed in patients with inflammatory diseases, cancer, infections, and other disorders. Although eosinophils are infrequently observed within the liver during periods of homeostasis, they are recruited to the liver in various liver diseases, including liver parasitosis, acute liver injury, autoimmune liver disease, and hepatocellular carcinoma. Furthermore, eosinophils have demonstrated the capacity to promote liver regeneration. This article explores the multifaceted roles of eosinophils in liver diseases, aiming to provide insights that could lead to more effective clinical therapies for these conditions.

Eosinophil-Associated Genes are Potential Biomarkers for Hepatocellular Carcinoma Prognosis

Background: Eosinophils, a type of white blood cell originating from the bone marrow, are widely believed to play a crucial role in inflammatory processes, including allergic reactions and parasitic infections. However, the relationship between eosinophils and liver cancer is not well understood. Methods: Tumor immune infiltration scores were calculated using single-sample Gene Set Enrichment Analysis (ssGSEA). Key modules and hub genes associated with eosinophils were screened using Weighted Gene Co-expression Network Analysis (WGCNA). Univariate and multivariate Cox analyses, along with LASSO regression, were used to identify prognostic genes and create a risk model. The Tumor Immune Dysfunction and Exclusion (TIDE) score was used to evaluate the immunotherapeutic significance of the eosinophil-associated gene risk score (ERS) model. Experiments such as flow cytometry, immunohistochemical analysis, real-time quantitative PCR (RT-qPCR), and Western blotting were used to determine gene expression levels and the status of eosinophil infiltration in tumors. Results: A risk trait model including 4 eosinophil-associated genes (RAMP3, G6PD, SSRP1, PLOD2) was developed by univariate Cox analysis and Lasso screening. Pathologic grading (p < 0.001) and model risk scores (p < 0.001) were found to be independent predictors of hepatocellular carcinoma (HCC) patient survival. Western blotting revealed higher levels of eosinophil peroxidase (EPX) in HCC tissues compared to adjacent normal tissues. Immunohistochemistry showed that eosinophils mainly infiltrated the connective tissue around HCC. The HCC samples showed low expression of RAMP3 and high expression of G6PD, SSRP1, and PLOD2, as detected by IHC and RT-qPCR analysis. The in vivo mouse experiments showed that IL-33 treatment induced the recruitment of eosinophils and reduced the number of intrahepatic tumor nodules. Conclusion: Overall, eosinophil infiltration in HCC is significantly correlated with patient survival. The risk assessment model based on eosinophil-related genes serves as a reliable clinical prognostic indicator and provides insights for precise treatment of HCC.

In-situ evaluation the fluctuation of hypochlorous acid in acute liver injury mice models with a mitochondria-targeted NIR ratiometric fluorescent probe

Acute liver injury (ALI) is a frequent and devastating liver disease that has been made more prevalent by the excessive use of chemicals, drugs, and alcohol in modern life. Hypochlorous acid (HClO), an important biomarker of oxidative stress originating mainly from the mitochondria, has been shown to be intimately connected to the development and course of ALI. Herein, a novel BODIPY-based NIR ratiometric fluorescent probe Mito-BS was constructed for the specific recognition of mitochondrial HClO. The probe Mito-BS can rapidly respond to HClO within 20 s with a ratiometric fluorescence response (from 680 nm to 645 nm), 24-fold fluorescence intensity ratio enhancement (I645/I680), a wide pH adaptation range (5-9) and the low detection limit (31 nM). The probe Mito-BS has been effectively applied to visualize endogenous and exogenous HClO fluctuations in living zebrafish and cells based on its low cytotoxicity and prominent mitochondria-targeting ability. Furthermore, the fluorescent probe Mito-BS makes it possible to achieve the non-invasive in-situ diagnosis of ALI through in mice, and provides a feasible strategy for early diagnosis and drug therapy of ALI and its complications.

Novel IL-4/HB-EGF-dependent crosstalk between eosinophils and macrophages controls liver regeneration after ischaemia and reperfusion injury

OBJECTIVE

Previous studies indicate that eosinophils are recruited into the allograft following orthotopic liver transplantation and protect from ischaemia reperfusion (IR) injury. In the current studies, we aim to explore whether their protective function could outlast during liver repair.

DESIGN

Eosinophil-deficient mice and adoptive transfer of bone marrow-derived eosinophils (bmEos) were employed to investigate the effects of eosinophils on tissue repair and regeneration after hepatic IR injury. Aside from exogenous cytokine or neutralising antibody treatments, mechanistic studies made use of a panel of mouse models of eosinophil-specific IL-4/IL-13-deletion, cell-specific IL-4rα-deletion in liver macrophages and hepatocytes and macrophage-specific deletion of heparin-binding epidermal growth factor-like growth factor (hb-egf).

RESULT

We observed that eosinophils persisted over a week following hepatic IR injury. Their peak accumulation coincided with that of hepatocyte proliferation. Functional studies showed that eosinophil deficiency was associated with a dramatic delay in liver repair, which was normalised by the adoptive transfer of bmEos. Mechanistic studies demonstrated that eosinophil-derived IL-4, but not IL-13, was critically involved in the reparative function of these cells. The data further revealed a selective role of macrophage-dependent IL-4 signalling in liver regeneration. Eosinophil-derived IL-4 stimulated macrophages to produce HB-EGF. Moreover, macrophage-specific hb-egf deletion impaired hepatocyte regeneration after IR injury.

CONCLUSION

Together, these studies uncovered an indispensable role of eosinophils in liver repair after acute injury and identified a novel crosstalk between eosinophils and macrophages through the IL-4/HB-EGF axis.

Endogenous PGD2 acting on DP2 receptor counter regulates Schistosoma mansoni infection-driven hepatic granulomatous fibrosis

Identifying new molecular therapies targeted at the severe hepatic fibrosis associated with the granulomatous immune response to Schistosoma mansoni infection is essential to reduce fibrosis-related morbidity/mortality in schistosomiasis. In vitro cell activation studies suggested the lipid molecule prostaglandin D2 (PGD2) as a potential pro-fibrotic candidate in schistosomal context, although corroboratory in vivo evidence is still lacking. Here, to investigate the role of PGD2 and its cognate receptor DP2 in vivo, impairment of PGD2 synthesis by HQL-79 (an inhibitor of the H-PGD synthase) or DP2 receptor inhibition by CAY10471 (a selective DP2 antagonist) were used against the fibrotic response of hepatic eosinophilic granulomas of S. mansoni infection in mice. Although studies have postulated PGD2 as a fibrogenic molecule, HQL-79 and CAY10471 amplified, rather than attenuated, the fibrotic response within schistosome hepatic granulomas. Both pharmacological strategies increased hepatic deposition of collagen fibers - an unexpected outcome accompanied by further elevation of hepatic levels of the pro-fibrotic cytokines TGF-β and IL-13 in infected animals. In contrast, infection-induced enhanced LTC4 synthesis in the schistosomal liver was reduced after HQL-79 and CAY10471 treatments, and therefore, inversely correlated with collagen production in granulomatous livers. Like PGD2-directed maneuvers, antagonism of cysteinyl leukotriene receptors CysLT1 by MK571 also promoted enhancement of TGF-β and IL-13, indicating a key down-regulatory role for endogenous LTC4 in schistosomiasis-induced liver fibrosis. An ample body of data supports the role of S. mansoni-driven DP2-mediated activation of eosinophils as the source of LTC4 during infection, including: (i) HQL-79 and CAY10471 impaired systemic eosinophilia, drastically decreasing eosinophils within peritoneum and hepatic granulomas of infected animals in parallel to a reduction in cysteinyl leukotrienes levels; (ii) peritoneal eosinophils were identified as the only cells producing LTC4 in PGD2-mediated S. mansoni-induced infection; (iii) the magnitude of hepatic granulomatous eosinophilia positively correlates with S. mansoni-elicited hepatic content of cysteinyl leukotrienes, and (iv) isolated eosinophils from S. mansoni-induced hepatic granuloma synthesize LTC4 in vitro in a PGD2/DP2 dependent manner. So, our findings uncover that granulomatous stellate cells-derived PGD2 by activating DP2 receptors on eosinophils does stimulate production of anti-fibrogenic cysLTs, which endogenously down-regulates the hepatic fibrogenic process of S. mansoni granulomatous reaction - an in vivo protective function which demands caution in the future therapeutic attempts in targeting PGD2/DP2 in schistosomiasis.

Self-Sulfhydrated, Nitro-Fixed Albumin Nanoparticles as a Potent Therapeutic Agent for the Treatment of Acute Liver Injury

Exogenous polysulfhydryls (R-SH) supplementation and nitric oxide (NO) gas molecules delivery provide essential antioxidant buffering pool components and anti-inflammatory species in cellular defense against injury, respectively. Herein, the intermolecular disulfide bonds in bovine serum albumin (BSA) molecules were reductively cleaved under native and mild conditions to expose multiple sulfhydryl groups (BSA-SH), then sulfhydryl-nitrosylated (R-SNO), and nanoprecipitated to form injectable self-sulfhydrated, nitro-fixed albumin nanoparticles (BSA-SNO NPs), allowing albumin to act as a NO donor reservoir and multiple sulfhydryl group transporter while also preventing unfavorable oxidation and self-cross-linking of polysulfhydryl groups. In two mouse models of ischemia/reperfusion-induced and endotoxin-induced acute liver injury (ALI), a single low dosage of BSA-SNO NPs (S-nitrosothiols: 4 μmol·kg-1) effectively attenuated oxidative stress and systemic inflammation cascades in the upstream pathophysiology of disease progression, thus rescuing dying hepatocytes, regulating host defense, repairing microcirculation, and restoring liver function. By mechanistically upregulating the antioxidative signaling pathway (Nrf-2/HO-1/NOQ1) and inhibiting the inflammatory cytokine storm (NF-κB/p-IκBα/TNF-α/IL-β), BSA-SNO NPs blocked the initiation of the mitochondrial apoptotic signaling pathway (Cyto C/Bcl-2 family/caspase-3) and downregulated the cell pyroptosis pathway (NLRP3/ASC/IL-1β), resulting in an increased survival rate from 26.7 to 73.3%. This self-sulfhydrated, nitro-fixed functionalized BSA nanoformulation proposes a potential drug-free treatment strategy for ALI.

The protective role of GATA6+ pericardial macrophages in pericardial inflammation

Prior research has suggested that GATA6+ pericardial macrophages may traffic to the myocardium to prevent interstitial fibrosis after myocardial infarction (MI), while subsequent literature claims that they do not. We demonstrate that GATA6+ pericardial macrophages are critical for preventing IL-33 induced pericarditis and attenuate trafficking of inflammatory monocytes and granulocytes to the pericardial cavity after MI. However, absence of GATA6+ macrophages did not affect myocardial inflammation due to MI or coxsackievirus-B3 induced myocarditis, or late-stage cardiac fibrosis and cardiac function post MI. GATA6+ macrophages are significantly less transcriptionally active following stimulation in vitro compared to bone marrow-derived macrophages and do not induce upregulation of inflammatory markers in fibroblasts. This suggests that GATA6+ pericardial macrophages attenuate inflammation through their interactions with surrounding cells. We therefore conclude that GATA6+ pericardial macrophages are critical in modulating pericardial inflammation, but do not play a significant role in controlling myocardial inflammation or fibrosis.

Good Cells Go Bad: Immune Dysregulation in the Transition from Acute Liver Injury to Liver Failure After Acetaminophen Overdose

The role of inflammatory cells and other components of the immune system in acetaminophen (APAP)-induced liver injury and repair has been extensively investigated. Although this has resulted in a wealth of information regarding the function and regulation of immune cells in the liver after injury, apparent contradictions have fueled controversy around the central question of whether the immune system is beneficial or detrimental after APAP overdose. Ultimately, this may not be a simple assignment of "good" or "bad." Clinical studies have clearly demonstrated an association between immune dysregulation and a poor outcome in patients with severe liver damage/liver failure induced by APAP overdose. To date, studies in mice have not uniformly replicated this connection. The apparent disconnect between clinical and experimental studies has perhaps stymied progress and further complicated investigation of the immune system in APAP-induced liver injury. Mouse models are often dismissed as not recapitulating the clinical scenario. Moreover, clinical investigation is most often focused on the most severe APAP overdose patients, those with liver failure. Notably, recent studies have made it apparent that the functional role of the immune system in the pathogenesis of APAP-induced liver injury is highly context dependent and greatly influenced by the experimental conditions. In this review, we highlight some of these recent findings and suggest strategies seeking to resolve and build on existing disconnects in the literature. SIGNIFICANCE STATEMENT: Acetaminophen overdose is the most frequent cause of acute liver failure in the United States. Studies indicate that dysregulated innate immunity contributes to the transition from acute liver injury to acute liver failure. In this review, we discuss the evidence for this and the potential underlying causes.

GPR116 alleviates acetaminophen-induced liver injury in mice by inhibiting endoplasmic reticulum stress

BACKGROUND

Acetaminophen (APAP) overdose is a significant contributor to drug-induced liver injury worldwide. G-protein-coupled receptor 116 (GPR116) is an important homeostatic maintenance molecule in the body, but little is known about its role in APAP-induced liver injury (AILI).

METHODS

GPR116 expression was determined in both human and mouse AILI models. Hepatic function and damage response were analyzed in hepatocyte-specific GPR116 deletion (GPR116△HC) mice undergoing APAP challenge. RNA-sequencing, immunofluorescence confocal, and co-immunoprecipitation (CO-IP) were employed to elucidate the impact and underlying mechanisms of GPR116 in AILI.

RESULTS

Intrahepatic GPR116 was upregulated in human and mice with AILI. GPR116△HC mice were vulnerable to AILI compared to wild-type mice. Overexpression of GPR116 effectively mitigated AILI in wild-type mice and counteracted the heightened susceptibility of GPR116△HC mice to APAP. Mechanistically, GPR116 inhibits the binding immunoglobulin protein (BiP), a critical regulator of ER function, through its interaction with β-arrestin1, thereby mitigating ER stress during the early stage of AILI. Additionally, the activation of GPR116 by ligand FNDC4 has been shown to confer a protective effect against early hepatotoxicity caused by APAP in murine model.

CONCLUSIONS

Upregulation of GPR116 on hepatocytes inhibits ER stress by binding to β-arrestin1, protecting mice from APAP-induced hepatotoxicity. GPR116 may serve as a promising therapeutic target for AILI.

Identification and validation of cuproptosis-related genes in acetaminophen-induced liver injury using bioinformatics analysis and machine learning

BACKGROUND

Acetaminophen (APAP) is commonly used as an antipyretic analgesic. However, acetaminophen overdose may contribute to liver injury and even liver failure. Acetaminophen-induced liver injury (AILI) is closely related to mitochondrial oxidative stress and dysfunction, which play critical roles in cuproptosis. Here, we explored the potential role of cuproptosis-related genes (CRGs) in AILI.

METHODS

The gene expression profiles were obtained from the Gene Expression Omnibus database. The differential expression of CRGs was determined between the AILI and control samples. Protein protein interaction, correlation, and functional enrichment analyses were performed. Machine learning was used to identify hub genes. Immune infiltration was evaluated. The AILI mouse model was established by intraperitoneal injection of APAP solution. Quantitative real-time PCR and western blotting were used to validate hub gene expression in the AILI mouse model. The copper content in the mouse liver samples and AML12 cells were quantified using a colorimetric assay kit. Ammonium tetrathiomolybdate (ATTM), was administered to mouse models and AML12 cells in order to investigate the effects of copper chelator on AILI.

RESULTS

The analysis identified 7,809 differentially expressed genes, 4,245 of which were downregulated and 3,564 of which were upregulated. Four optimal feature genes (OFGs; SDHB, PDHA1, NDUFB2, and NDUFB6) were identified through the intersection of two machine learning algorithms. Further nomogram, decision curve, and calibration curve analyses confirmed the diagnostic predictive efficacy of the four OFGs. Enrichment analysis indicated that the OFGs were involved in multiple pathways, such as IL-17 pathway and chemokine signaling pathway, that are related to AILI progression. Immune infiltration analysis revealed that macrophages were more abundant in AILI than in control samples, whereas eosinophils and endothelial cells were less abundant. Subsequently, the AILI mouse model was successfully established, and histopathological analysis using hematoxylin-eosin staining along with liver function tests revealed a significant induction of liver injury in the APAP group. Consistent with expectations, both mRNA and protein levels of the four OFGs exhibited a substantial decrease. The administration of ATTAM effectively mitigates copper elevation induced by APAP in both mouse model and AML12 cells. However, systemic administration of ATTM did not significantly alleviate AILI in the mouse model.

CONCLUSION

This study first revealed the potential role of CRGs in the pathological process of AILI and offered novel insights into its underlying pathogenesis.

The intricate dance of tumor evolution: Exploring immune escape, tumor migration, drug resistance, and treatment strategies

Recent research has unveiled fascinating insights into the intricate mechanisms governing tumor evolution. These studies have illuminated how tumors adapt and proliferate by exploiting various factors, including immune evasion, resistance to therapeutic drugs, genetic mutations, and their ability to adapt to different environments. Furthermore, investigations into tumor heterogeneity and chromosomal aberrations have revealed the profound complexity that underlies the evolution of cancer. Emerging findings have also underscored the role of viral influences in the development and progression of cancer, introducing an additional layer of complexity to the field of oncology. Tumor evolution is a dynamic and complex process influenced by various factors, including immune evasion, drug resistance, tumor heterogeneity, and viral influences. Understanding these elements is indispensable for developing more effective treatments and advancing cancer therapies. A holistic approach to studying and addressing tumor evolution is crucial in the ongoing battle against cancer. The main goal of this comprehensive review is to explore the intricate relationship between tumor evolution and critical aspects of cancer biology. By delving into this complex interplay, we aim to provide a profound understanding of how tumors evolve, adapt, and respond to treatment strategies. This review underscores the pivotal importance of comprehending tumor evolution in shaping effective approaches to cancer treatment.

Circulating myeloid populations have prognostic utility in alcohol-related liver disease

Introduction

Alcohol-related liver disease (ARLD) accounts for over one third of all deaths from liver conditions, and mortality from alcohol-related liver disease has increased nearly five-fold over the last 30 years. Severe alcohol-related hepatitis almost always occurs in patients with a background of chronic liver disease with extensive fibrosis or cirrhosis, can precipitate 'acute on chronic' liver failure and has a high short-term mortality. Patients with alcohol-related liver disease have impaired immune responses, and increased susceptibility to infections, thus prompt diagnosis of infection and careful patient management is required. The identification of early and non-invasive diagnostic and prognostic biomarkers in ARLD remains an unresolved challenge. Easily calculated predictors of infection and mortality are required for use in patients who often exhibit variable symptoms and disease severity and may not always present in a specialized gastroenterology unit.

Methods

We have used a simple haematological analyser to rapidly measure circulating myeloid cell parameters across the ARLD spectrum.

Results and Discussion

We demonstrate for the first time that immature granulocyte (IG) counts correlate with markers of disease severity, and our data suggests that elevated counts are associated with increased short-term mortality and risk of infection. Other myeloid populations such as eosinophils and basophils also show promise. Thus IG count has the potential to serve alongside established markers such as neutrophil: lymphocyte ratio as a simply calculated predictor of mortality and risk of infectious complications in patients with alcohol-related hepatitis. This would allow identification of patients who may require more intensive management.

Investigation of the usefulness of liver-specific deconvolution method by establishing a liver benchmark dataset

Immune responses in the liver are related to the development and progression of liver failure, and precise prediction of their behavior is important. Deconvolution is a methodology for estimating the immune cell proportions from the transcriptome, and it is mainly applied to blood-derived samples and tumor tissues. However, the influence of tissue-specific modeling on the estimation results has rarely been investigated. Here, we constructed a system to evaluate the performance of the deconvolution method on liver transcriptome data. We prepared seven mouse liver injury models using small-molecule compounds and established a benchmark dataset with corresponding liver bulk RNA-Seq and immune cell proportions. RNA-Seq expression for nine leukocyte subsets and four liver-associated cell types were obtained from the Gene Expression Omnibus to provide a reference. We found that the combination of reference cell sets affects the estimation results of reference-based deconvolution methods and established a liver-specific deconvolution by optimizing the reference cell set for each cell to be estimated. We applied this model to independent datasets and showed that liver-specific modeling is highly extrapolatable. We expect that this approach will enable sophisticated estimation from rich tissue data accumulated in public databases and to obtain information on aggregated immune cell trafficking.

Deficiency of purinergic P2X4 receptor alleviates experimental autoimmune hepatitis in mice

Purinergic P2X4 receptor (P2X4R) has been shown to have immunomodulatory properties in infection, inflammation, and organ damage including liver regeneration and fibrosis. However, the mechanisms and pathophysiology associated with P2X4R during acute liver injury remain unknown. We used P2X4R-/- mice to explore the role of P2X4R in three different models of acute liver injury caused by concanavalin A (ConA), carbon tetrachloride, and acetaminophen. ConA treatment results in an increased expression of P2X4R in the liver of mice, which was positively correlated with higher levels of aspartate aminotransferase and alanine aminotransferase in the serum. However, P2X4R gene ablation significantly reduced the severity of acute hepatitis in mice caused by ConA, but not by carbon tetrachloride or acetaminophen. The protective benefits against immune-mediated acute hepatitis were achieved via modulating inflammation (Interleukin (IL)-1β, IL-6, IL-17A, interferon-γ, tumor necrosis factor-α), oxidative stress (malondialdehyde, superoxide dismutase, glutathione peroxidase, and catalase), apoptosis markers (Bax, Bcl-2, and Caspase-3), autophagy biomarkers (LC3, Beclin-1, and p62), and nucleotide oligomerization domain-likereceptorprotein 3(NLRP3) inflammasome-activated pyroptosis markers (NLRP3, Gasdermin D, Caspase-1, ASC, IL-1β). Additionally, administration of P2X4R antagonist (5-BDBD) or agonist (cytidine 5'-triphosphate) either improved or worsened ConA-induced autoimmune hepatitis, respectively. This study is the first to reveal that the absence of the P2X4 receptor may mitigate immune-mediated liver damage, potentially by restraining inflammation, oxidation, and programmed cell death mechanisms. And highlight P2X4 receptor is essential for ConA-induced acute hepatitis.

Eosinophils promote CD8+ T cell memory generation to potentiate anti-bacterial immunity

Memory CD8+ T cell generation is crucial for pathogen elimination and effective vaccination against infection. The cellular and molecular circuitry that underlies the generation of memory CD8+ T cells remains elusive. Eosinophils can modulate inflammatory allergic responses and interact with lymphocytes to regulate their functions in immune defense. Here we report that eosinophils are required for the generation of memory CD8+ T cells by inhibiting CD8+ T cell apoptosis. Eosinophil-deficient mice display significantly impaired memory CD8+ T cell response and weakened resistance against Listeria monocytogenes (L.m.) infection. Mechanistically, eosinophils secrete interleukin-4 (IL-4) to inhibit JNK/Caspase-3 dependent apoptosis of CD8+ T cells upon L.m. infection in vitro. Furthermore, active eosinophils are recruited into the spleen and secrete more IL-4 to suppress CD8+ T cell apoptosis during early stage of L.m. infection in vivo. Adoptive transfer of wild-type (WT) eosinophils but not IL-4-deficient eosinophils into eosinophil-deficient mice could rescue the impaired CD8+ T cell memory responses. Together, our findings suggest that eosinophil-derived IL-4 promotes the generation of CD8+ T cell memory and enhances immune defense against L.m. infection. Our study reveals a new adjuvant role of eosinophils in memory T cell generation and provides clues for enhancing the vaccine potency via targeting eosinophils and related cytokines.

Visualization of therapeutic intervention for acute liver injury using low-intensity pulsed ultrasound-responsive phase variant nanoparticles

Acute liver injury (ALI) is a highly fatal condition characterized by sudden massive necrosis of liver cells, inflammation, and impaired coagulation function. Currently, the primary clinical approach for managing ALI involves symptom management based on the underlying causes. The association between excessive reactive oxygen species originating from macrophages and acute liver injury is noteworthy. Therefore, we designed a novel nanoscale phase variant contrast agent, denoted as PFP@CeO2@Lips, which effectively scavenges reactive oxygen species, and enables visualization through low intensity pulsed ultrasound activation. The efficacy of the nanoparticles in scavenging excess reactive oxygen species from RAW264.7 and protective AML12 cells has been demonstrated through in vitro and in vivo experiments. Additionally, these nanoparticles have shown a protective effect against LPS/D-GalN attack in C57BL/6J mice. Furthermore, when exposed to LIPUS irritation, the nanoparticles undergo liquid-gas phase transition and enable ultrasound imaging.

Nutrient-derived signals regulate eosinophil adaptation to the small intestine

Eosinophils are well recognized as effector cells of type 2 immunity, yet they also accumulate in many tissues under homeostatic conditions. However, the processes that govern homeostatic eosinophil accumulation and tissue-specific adaptation, and their functional significance, remain poorly defined. Here, we investigated how eosinophils adapt to the small intestine (SI) microenvironment and the local signals that regulate this process. We observed that eosinophils gradually migrate along the crypt-villus axis, giving rise to a villus-resident subpopulation with a distinct transcriptional signature. Retinoic acid signaling was specifically required for maintenance of this subpopulation, while IL-5 was largely dispensable outside of its canonical role in eosinophil production. Surprisingly, we found that a high-protein diet suppressed the accumulation of villus-resident eosinophils. Purified amino acids were sufficient for this effect, which was a consequence of accelerated eosinophil turnover within the tissue microenvironment and was not due to altered development in the bone marrow. Our study provides insight into the process of eosinophil adaptation to the SI, highlighting its reliance on nutrient-derived signals.

The dichotomic role of single cytokines: Fine-tuning immune responses

Cytokines are known for their pleiotropic effects. They can be classified by their function as pro-inflammatory, such as tumor necrosis factor (TNF), interleukin (IL) 1 and IL-12, or anti-inflammatory, like IL-10, IL-35 and transforming growth factor β (TGF-β). Though this type of classification is an important simplification for the understanding of the general cytokine's role, it can be misleading. Here, we discuss recent studies that show a dichotomic role of the so-called pro and anti-inflammatory cytokines, highlighting that their function can be dependent on the microenvironment and their concentrations. Furthermore, we discuss how the back-and-forth interplay between cytokines and immunometabolism can influence the dichotomic role of inflammatory responses as an important target to complement cytokine-based therapies.

Bioinformatics-led discovery of liver-specific genes and macrophage infiltration in acute liver injury

Background

Acute liver injury (ALI) is an important global health concern, primarily caused by widespread hepatocyte cell death, coupled with a complex immune response and a lack of effective remedies. This study explores the underlying mechanisms, immune infiltration patterns, and potential targets for intervention and treatment ALI.

Methods

The datasets of acetaminophen (APAP), carbon tetrachloride (CCl4), and lipopolysaccharide (LPS)-induced ALI were obtained from the GEO database. Differentially expressed genes (DEGs) were individually identified using the limma packages. Functional enrichment analysis was performed using KEGG, GO, and GSEA methods. The overlapping genes were extracted from the three datasets, and hub genes were identified using MCODE and CytoHubba algorithms. Additionally, PPI networks were constructed based on the String database. Immune cell infiltration analysis was conducted using ImmuCellAI, and the correlation between hub genes and immune cells was determined using the Spearman method. The relationship between hub genes, immune cells, and biochemical indicators of liver function (ALT, AST) was validated using APAP and triptolide (TP) -induced ALI mouse models.

Results

Functional enrichment analysis indicated that all three ALI models were enriched in pathways linked to fatty acid metabolism, drug metabolism, inflammatory response, and immune regulation. Immune analysis revealed a significant rise in macrophage infiltration. A total of 79 overlapping genes were obtained, and 10 hub genes were identified that were consistent with the results of the biological information analysis after screening and validation. Among them, Clec4n, Ms4a6d, and Lilrb4 exhibited strong associations with macrophage infiltration and ALI.

Eosinophils in obesity and obesity-associated disorders

Despite the rising prevalence and costs for the society, obesity etiology, and its precise cellular and molecular mechanisms are still insufficiently understood. The excessive accumulation of fat by adipocytes plays a key role in obesity progression and has many repercussions on total body physiology. In recent years the immune system as a gatekeeper of adipose tissue homeostasis has been evidenced and has become a focal point of research. Herein we focus on eosinophils, an important component of type 2 immunity, assuming fundamental, yet ill-defined, roles in the genesis, and progression of obesity and related metabolic disorders. We summarize eosinophilopoiesis and eosinophils recruitment into adipose tissue and discuss how the adipose tissue environments shape their function and vice versa. Finally, we also detail how obesity transforms the local eosinophil niche. Understanding eosinophil crosstalk with the diverse cell types within the adipose tissue environment will allow us to framework the therapeutic potential of eosinophils in obesity.

Mesenchymal stem cell-regulated miRNA-mRNA landscape in acute-on-chronic liver failure

BACKGROUND

Acute-on-chronic liver failure (ACLF) is a major challenge in the field of hepatology. While mesenchymal stem cell (MSC) therapy can improve the prognosis of patients with ACLF, the molecular mechanisms through which MSCs attenuate ACLF remain poorly understood. We performed global miRNA and mRNA expression profiling via next-generation sequencing of liver tissues from MSC-treated ACLF mice to identify important signaling pathways and major factors implicated in ACLF alleviation by MSCs.

METHODS

Carbon tetrachloride-induced ACLF mice were treated with saline or mouse bone marrow-derived MSCs. Mouse livers were subjected to miRNA and mRNA sequencing. Related signal transduction pathways were obtained through Gene Set Enrichment Analysis. Functional enrichment, protein-protein interaction, and immune infiltration analyses were performed for the differentially expressed miRNA target genes (DETs). Hub miRNA and mRNA associated with liver injury were analyzed using LASSO regression. The expression levels of hub genes were subjected to Pearson's correlation analysis and verified using RT-qPCR. The biological functions of hub genes were verified in vitro.

RESULTS

The tricarboxylic acid cycle and peroxisome proliferator-activated receptor pathways were activated in the MSC-treated groups. The proportions of liver-infiltrating NK resting cells, M2 macrophages, follicular helper T cells, and other immune cells were altered after MSC treatment. The expression levels of six miRNAs and 10 transcripts correlated with the degree of liver injury. miR-27a-5p was downregulated in the mouse liver after MSC treatment, while its target gene E2f2 was upregulated. miR-27a-5p inhibited E2F2 expression, suppressed G1/S phase transition and proliferation of hepatocytes, in addition to promoting their apoptosis.

CONCLUSIONS

This is the first comprehensive analysis of miRNA and mRNA expression in the liver tissue of ACLF mice after MSC treatment. The results revealed global changes in hepatic pathways and immune subpopulations. The miR-27a-5p/E2F2 axis emerged as a central regulator of the MSC-induced attenuation of ACLF. The current findings improve our understanding of the molecular mechanisms through which MSCs alleviate ACLF.

IL-33 Downregulates Hepatic Carboxylesterase 1 in Acute Liver Injury via Macrophage-derived Exosomal miR-27b-3p

Background and Aims

We previously reported that carboxylesterase 1 (CES1) expression was suppressed following liver injury. The study aimed to explore the role of interleukin (IL)-33 in liver injury and examine the mechanism by which IL-33 regulates CES1.

Methods

IL-33 and CES1 levels were determined in the livers of patients and lipopolysaccharide (LPS)-, acetaminophen (APAP)-treated mice. We constructed IL-33 and ST2 knockout (KO) mice. ST2-enriched immune cells in livers were screened to identify the responsible cells. Macrophage-derived exosome (MDE) activity was tested by adding exosome inhibitors. Micro-RNAs (miRs) were extracted from control and IL-33-stimulated MDEs (IL-33-MDEs) and subjected miR sequencing (miR-Seq). Candidate miR was tested in vitro and in vivo and its binding of a target gene was assessed by luciferase reporter assays. Lentivirus-vector cellular transfection and transcript silencing were used to examine pathways mediating IL-33 suppression of miR-27b-3p.

Results

Patient liver IL-33 and CES1 expression levels were inversely correlated. CES1 downregulation in liver injury was rescued in both IL-33-deficient and ST2 KO mice. Macrophages were shown to be responsible for IL-33 effects. IL-33-MDEs reduced CES1 levels in hepatocytes. Exosomal miR-Seq and qRT-PCR demonstrated increased miR-27b-3p levels in IL-33-MDEs; miR-27b-3p was implicated in Nrf2 targeting. IL-33 inhibition of miR-27b-3p was found to be GATA3-dependent.

Conclusions

IL-33-ST2-GATA3 pathway signaling increases miR-27b-3p content in MDEs, which upon being internalized by hepatocytes reduce CES1 expression by inhibiting Nrf2. The elucidation of this mechanism in this study contributes to a better understanding of CES1 dysregulation in liver injury.

Type 2 innate lymphoid cells are protective against hepatic ischaemia/reperfusion injury

BACKGROUND AND AIMS

Although type 2 innate lymphoid cells (ILC2s) were originally found to be liver-resident lymphocytes, the role and importance of ILC2 in liver injury remains poorly understood. In the current study, we sought to determine whether ILC2 is an important regulator of hepatic ischaemia/reperfusion injury (IRI).

METHODS

ILC2-deficient mice (ICOS-T or NSG) and genetically modified ILC2s were used to investigate the role of ILC2s in murine hepatic IRI. Interactions between ILC2s and eosinophils or macrophages were studied in coculture. The role of human ILC2s was assessed in an immunocompromised mouse model of hepatic IRI.

RESULTS

Administration of IL-33 prevented hepatic IRI in association with reduction of neutrophil infiltration and inflammatory mediators in the liver. IL-33-treated mice had elevated numbers of ILC2s, eosinophils, and regulatory T cells. Eosinophils, but not regulatory T cells, were required for IL-33-mediated hepatoprotection in IRI mice. Depletion of ILC2s substantially abolished the protective effect of IL-33 in hepatic IRI, indicating that ILC2s play critical roles in IL-33-mediated liver protection. Adoptive transfer of ex vivo-expanded ILC2s improved liver function and attenuated histologic damage in mice subjected to IRI. Mechanistic studies combining genetic and adoptive transfer approaches identified a protective role of ILC2s through promoting IL-13-dependent induction of anti-inflammatory macrophages and IL-5-dependent elevation of eosinophils in IRI. Furthermore, in vivo expansion of human ILC2s by IL-33 or transfer of ex vivo-expanded human ILC2s ameliorated hepatic IRI in an immunocompromised mouse model of hepatic IRI.

CONCLUSIONS

This study provides insight into the mechanisms of ILC2-mediated liver protection that could serve as therapeutic targets to treat acute liver injury.

IMPACT AND IMPLICATIONS

We report that type 2 innate lymphoid cells (ILC2s) are important regulators in a mouse model of liver ischaemia/reperfusion injury (IRI). Through manipulation of macrophage and eosinophil phenotypes, ILC2s mitigate liver inflammation and injury during liver IRI. We propose that ILC2s have the potential to serve as a therapeutic tool for protecting against acute liver injury and lay the foundation for translation of ILC2 therapy to human liver disease.

Updates on the Immune Cell Basis of Hepatic Ischemia-Reperfusion Injury

Liver ischemia-reperfusion injury (IRI) is the main cause of organ dysfunction and failure after liver surgeries including organ transplantation. The mechanism of liver IRI is complex and numerous signals are involved but cellular metabolic disturbances, oxidative stress, and inflammation are considered the major contributors to liver IRI. In addition, the activation of inflammatory signals exacerbates liver IRI by recruiting macrophages, dendritic cells, and neutrophils, and activating NK cells, NKT cells, and cytotoxic T cells. Technological advances enable us to understand the role of specific immune cells during liver IRI. Accordingly, therapeutic strategies to prevent or treat liver IRI have been proposed but no definitive and effective therapies exist yet. This review summarizes the current update on the immune cell functions and discusses therapeutic potentials in liver IRI. A better understanding of this complex and highly dynamic process may allow for the development of innovative therapeutic approaches and optimize patient outcomes.

Correlation between serum pro-inflammatory cytokine levels and the prognosis of the patients with acute liver failure

BACKGROUND AND AIM

The prognosis of acute liver failure (ALF) remains poor, and liver transplantation is an alternative treatment option. Assessing the prognosis of ALF is important in determining treatment strategies. Here, we investigated clinical factors including serum pro-inflammatory cytokine levels that are associated with the prognosis of ALF.

METHODS

Sixty-six patients who developed ALF were enrolled in this study. Serum concentrations of 12 pro-inflammatory cytokines were measured on admission. The prognosis and factors associated with survival and development of hepatic coma were analyzed.

RESULTS

Of 66 patients, 4 patients underwent liver transplantation, and 49 patients were rescued without liver transplantation, while the remaining 13 patients died. Serum concentrations of interleukin (IL)-1β, IL-4, IL-6, IL-8, IL-13, TNF, IFN -γ, IP-10, and G-CSF were significantly elevated in ALF patients. IL-4 and IL-8 levels were higher in patients who underwent liver transplantation or died than in rescued patients. Multivariable analysis identified age ≥ 55 years and IL-4 ≥ 1.2 pg/mL on admission as independent factors for mortality. Serum IL-8 levels were higher in patients with hepatic coma, and prothrombin-international normalized ratio ≥ 3.5 and IL-8 ≥ 77.2 pg/mL on admission were associated with development of hepatic coma after admission.

CONCLUSION

Serum levels of several pro-inflammatory cytokines were elevated in ALF patients. IL-4 and IL-8 were correlated with survival and development of hepatic coma after admission, respectively. Measurement of serum pro-inflammatory cytokines seems to be useful for the management of ALF.

Early-Life Exposure to Lipopolysaccharide Induces Persistent Changes in Gene Expression Profiles in the Liver and Spleen of Female FVB/N Mice

The objective of this study was to investigate how subcutaneous (sc) lipopolysaccharide (LPS) administration affects the gene expression profiles of insulin signaling as well as innate and adaptive immunity genes in mouse livers and spleens. FVB/N female mice were randomly assigned to one of two treatment groups at 5 weeks of age: (1) a six-week subcutaneous injection of saline at 11 μL/h (control-CON), or (2) a six-week subcutaneous injection of LPS from Escherichia coli 0111:B4 at 0.1 μg/g body weight at 11 μL/h. At 106 weeks (i.e., 742 days) after the last treatment, mice were euthanized. Following euthanasia, liver and spleen samples were collected, snap frozen, and stored at -80 °C until gene expression profiling. LPS upregulated nine genes in the liver, according to the findings (Pparg, Frs3, Kras, Raf1, Gsk3b, Rras2, Hk2, Pik3r2, and Myd88). With a 4.18-fold increase over the CON group, Pparg was the most up-regulated gene in the liver. Based on the annotation cluster analysis, LPS treatment upregulated liver genes which are involved in pathways associated with hepatic steatosis, B- and T-cell receptor signaling, chemokine signaling, as well as other types of cancers such as endometrial cancer, prostate cancer, and colorectal cancer. LPS increased the spleen expression of Ccl11, Ccl25, Il6, Cxcl5, Pparg, Tlr4, Nos2, Cxcl11, Il1a, Ccl17, and Fcgr3, all of which are involved in innate and adaptive immune responses and the regulation of cytokine production. Furthermore, functional analysis revealed that cytokine-cytokine receptor interaction and chemokine signaling pathways were the most enriched in LPS-treated mice spleen tissue. Our findings support the notion that early-life LPS exposure can result in long-term changes in gene expression profiling in the liver and spleen tissues of FVB/N female mice.

A dual role of inflammation in acetaminophen-induced liver injury

In many affluent nations, acetaminophen (APAP) overdose is the leading cause of drug-induced acute liver failure. The process of APAP-induced liver injury (AILI) is intimately tied to inflammation, including hepatocyte necrosis-caused initiation of inflammation, inflammation amplification that exacerbates liver injury, and the resolution of inflammation that triggers liver regeneration and repair. Excessive APAP metabolism in the liver eventually leads to hepatocyte necrosis and inflammation. Innate immune cells, such as neutrophils, eosinophils, monocytes, and gammadelta T cells, are recruited into the injured liver and release various cytokines. These immune cells and cytokines have been found to serve two purposes in AILI. In this review, we highlighted the dual role of inflammation, including inflammatory cytokines and inflammatory immune cells in AILI, and discussed possible explanations for contradictory findings.

Eosinophils protect against acetaminophen-induced liver injury through cyclooxygenase-mediated IL-4/IL-13 production

BACKGROUND AND AIMS

A better understanding of the underlying mechanism of acetaminophen (APAP)-induced liver injury (AILI) remains an important endeavor to develop therapeutic approaches. Eosinophils have been detected in liver biopsies of patients with APAP overdose. We recently demonstrated a profound protective role of eosinophils against AILI; however, the molecular mechanism had not been elucidated.

APPROACH AND RESULTS

In agreement with our previous data from experiments using genetic deletion of eosinophils, we found that depletion of eosinophils in wild-type (WT) mice by an anti-IL-15 antibody resulted in exacerbated AILI. Moreover, adoptive transfer of eosinophils significantly reduced liver injury and mortality rate in WT mice. Mechanistic studies using eosinophil-specific IL-4/IL-13 knockout mice demonstrated that these cytokines, through inhibiting interferon-γ, mediated the hepatoprotective function of eosinophils. Reverse phase protein array analyses and in vitro experiments using various inhibitors demonstrated that IL-33 stimulation of eosinophils activated p38 mitogen-activated protein kinase (MAPK), and in turn, cyclooxygenases (COX), which triggered NF-κB-mediated IL-4/IL-13 production. In vivo adoptive transfer experiments showed that in contrast to naive eosinophils, those pretreated with COX inhibitors failed to attenuate AILI.

CONCLUSIONS

The current study revealed that eosinophil-derived IL-4/IL-13 accounted for the hepatoprotective effect of eosinophils during AILI. The data demonstrated that the p38 MAPK/COX/NF-κB signaling cascade played a critical role in inducing IL-4/IL-13 production by eosinophils in response to IL-33.

Distinct T helper cell-mediated antitumor immunity: T helper 2 cells in focus

The adaptive arm of the immune system is crucial for appropriate antitumor immune responses. It is generally accepted that clusters of differentiation 4+ (CD4+) T cells, which mediate T helper (Th) 1 immunity (type 1 immunity), are the primary Th cell subtype associated with tumor elimination. In this review, we discuss evidence showing that antitumor immunity and better prognosis can be associated with distinct Th cell subtypes in experimental mouse models and humans, with a focus on Th2 cells. The aim of this review is to provide an overview and understanding of the mechanisms associated with different tumor outcomes in the face of immune responses by focusing on the (1) site of tumor development, (2) tumor properties (i. e., tumor metabolism and cytokine receptor expression), and (3) type of immune response that the tumor initially escaped. Therefore, we discuss how low-tolerance organs, such as lungs and brains, might benefit from a less tissue-destructive immune response mediated by Th2 cells. In addition, Th2 cells antitumor effects can be independent of CD8+ T cells, which would circumvent some of the immune escape mechanisms that tumor cells possess, like low expression of major histocompatibility-I (MHC-I). Finally, this review aims to stimulate further studies on the role of Th2 cells in antitumor immunity and briefly discusses emerging treatment options.

The immunological mechanisms and therapeutic potential in drug-induced liver injury: lessons learned from acetaminophen hepatotoxicity

Acute liver failure caused by drug overdose is a significant clinical problem in developed countries. Acetaminophen (APAP), a widely used analgesic and antipyretic drug, but its overdose can cause acute liver failure. In addition to APAP-induced direct hepatotoxicity, the intracellular signaling mechanisms of APAP-induced liver injury (AILI) including metabolic activation, mitochondrial oxidant stress and proinflammatory response further affect progression and severity of AILI. Liver inflammation is a result of multiple interactions of cell death molecules, immune cell-derived cytokines and chemokines, as well as damaged cell-released signals which orchestrate hepatic immune cell infiltration. The immunoregulatory interplay of these inflammatory mediators and switching of immune responses during AILI lead to different fate of liver pathology. Thus, better understanding the complex interplay of immune cell subsets in experimental models and defining their functional involvement in disease progression are essential to identify novel therapeutic targets for the treatment of AILI. Here, this present review aims to systematically elaborate on the underlying immunological mechanisms of AILI, its relevance to immune cells and their effector molecules, and briefly discuss great therapeutic potential based on inflammatory mediators.

Role of the chemokine system in liver fibrosis: a narrative review

BACKGROUND AND OBJECTIVE

Liver fibrosis is a disease with characteristics of an aberrant wound healing response. Fibrosis is commonly the end-stage for chronic liver diseases like alcohol-associated liver disease (ALD), metabolic-associated liver disease, viral hepatitis, and hepatic autoimmune disease. Innate immunity contributes to the progression of many diseases through multiple mechanisms including production of pro-inflammatory mediators, leukocyte infiltration and tissue injury. Chemokines and their receptors orchestrate accumulation and activation of immune cells in tissues and are associated with multiple liver diseases; however, much less is known about their potential roles in liver fibrosis. This is a narrative review of current knowledge of the relationship of chemokine biology to liver fibrosis with insights into potential future therapeutic opportunities that can be explored in the future.

METHODS

A comprehensive literature review was performed searching PubMed for relevant English studies and texts regarding chemokine biology, chronic liver disease and liver fibrosis published between 1993 and 2021. The review was written and constructed to detail the intriguing chemokine biology, the relation of chemokines to tissue injury and resolution, and identify areas of discovery for fibrosis treatment.

KEY CONTENT AND FINDINGS

Chemokines are implicated in many chronic liver diseases, regardless of etiology. Most of these diseases will progress to fibrosis without appropriate treatment. The contributions of chemokines to liver disease and fibrosis are diverse and include canonical roles of modulating hepatic inflammation as well as directly contributing to fibrosis via activation of hepatic stellate cells (HSCs). Limited clinical evidence suggests that targeting chemokines in certain liver diseases might provide a therapeutic benefit to patients with hepatic fibrosis.

CONCLUSIONS

The chemokine system of ligands and receptors is a complex network of inflammatory signals in nearly all diseases. The specific sources of chemokines and cellular targets lend unique pathophysiological consequences to chronic liver diseases and established fibrosis. Although most chemokines are pro-inflammatory and contribute to tissue injury, others likely aid in the resolution of established fibrosis. To date, very few targeted therapies exist for the chemokine system and liver disease and/or fibrosis, and further study could identify viable treatment options to improve outcomes in patients with end-stage liver disease.

Alanyl-Glutamine Protects against Lipopolysaccharide-Induced Liver Injury in Mice via Alleviating Oxidative Stress, Inhibiting Inflammation, and Regulating Autophagy

Acute liver injury is a worldwide problem with a high rate of morbidity and mortality, and effective pharmacological therapies are still urgently needed. Alanyl-glutamine (Ala-Gln), a dipeptide formed from L-alanine and L-glutamine, is known as a protective compound that is involved in various tissue injuries, but there are limited reports regarding the effects of Ala-Gln in acute liver injury. This present study aimed to investigate the protective effects of Ala-Gln in lipopolysaccharide (LPS)-induced acute liver injury in mice, with a focus on inflammatory responses and oxidative stress. The acute liver injury induced using LPS (50 μg/kg) and D-galactosamine (D-Gal) (400 mg/kg) stimulation in mice was significantly attenuated after Ala-Gln treatment (500 and 1500 mg/kg), as evidenced by reduced plasma alanine transaminase (ALT) (p < 0.01, p < 0.001), aspartate transaminase (AST) (p < 0.05, p < 0.001), and lactate dehydrogenase (LDH) (p < 0.01, p < 0.001) levels, and accompanied by improved histopathological changes. In addition, LPS/D-Gal-induced hepatic apoptosis was also alleviated by Ala-Gln administration, as shown by a greatly decreased ratio of TUNEL-positive hepatocytes, from approximately 10% to 2%, and markedly reduced protein levels of cleaved caspase-3 (p < 0.05, p < 0.001) in liver. Moreover, we found that LPS/D-Gal-triggered oxidative stress was suppressed after Ala-Gln treatment, the effect of which might be dependent on the elevation of SOD and GPX activities, and on GSH levels in liver. Interestingly, we observed that Ala-Gln clearly inhibited LPS/D-Gal exposure-induced macrophage accumulation and the production of proinflammatory factors in the liver. Furthermore, Ala-Gln greatly regulated autophagy in the liver in LPS/D-Gal-treated mice. Using RAW264.7 cells, we confirmed the anti-inflammatory role of Ala-Gln-targeting macrophages.