Pattern Recognition Receptors: Significance of Expression in the Liver

Protective effects of 17-β-estradiol on liver injury: The role of TLR4 signaling pathway and inflammatory response

Liver injury, a major global health issue, stems from various causes such as alcohol consumption, nonalcoholic steatohepatitis, obesity, diabetes, metabolic syndrome, hepatitis, and certain medications. The liver's unique susceptibility to ischemia and hypoxia, coupled with the critical role of the gut-liver axis in inflammation, underscores the need for effective therapeutic interventions. The study highlights E2's interaction with estrogen receptors (ERs) and its modulation of the Toll-like receptor 4 (TLR4) signaling pathway as key mechanisms in mitigating liver injury. Activation of TLR4 leads to the release of pro-inflammatory cytokines and chemokines, exacerbating liver inflammation and injury. E2 down-regulates TLR4 expression, reduces oxidative stress, and inhibits pro-inflammatory cytokines, thereby protecting the liver. Both classic (ERα and ERβ) and non-classic [G protein-coupled estrogen receptor (GPER)] receptors are influenced by E2. ERα is particularly crucial for liver regeneration, preventing liver failure by promoting hepatocyte proliferation. Furthermore, E2 exerts anti-inflammatory, antioxidant, and anti-apoptotic effects by inhibiting cytokines such as IL-6, IL-1β, TNF-α, and IL-17, and by reducing lipid peroxidation and free radical damage. The article calls for further clinical research to validate these findings and to develop estrogen-based treatments for liver injuries. Overall, the research emphasizes the significant potential of E2 as a therapeutic agent for liver injuries. It advocates for extensive clinical studies to validate E2 hepatoprotective properties and develop effective estrogen-based treatments.

Inflammatory Response in the Pathogenesis and Treatment of Hepatocellular Carcinoma: A Double-Edged Weapon

Hepatocellular carcinoma (HCC) is the most frequent among primary liver tumors (90%) and one of the main causes of cancer-related death. It develops usually in a chronically inflamed environment, ranging from compensatory parenchymal regeneration to fibrosis and cirrhosis: carcinogenesis can potentially happen in each of these stages. Inflammation determined by chronic viral infection (hepatitis B, hepatitis C, and hepatitis delta viruses) represents an important risk factor for HCC etiology through both viral direct damage and immune-related mechanisms. The deregulation of the physiological liver immunological network determined by viral infection can lead to carcinogenesis. The recent introduction of immunotherapy as the gold-standard first-line treatment for HCC highlights the role of the immune system and inflammation as a double-edged weapon in both HCC carcinogenesis and treatment. In this review we highlight how the inflammation is the key for the hepatocarcinogenesis in viral, alcohol and metabolic liver diseases.

Hepatocytes and the art of killing Plasmodium softly

The Plasmodium parasites that cause malaria undergo asymptomatic development in the parenchymal cells of the liver, the hepatocytes, prior to infecting erythrocytes and causing clinical disease. Traditionally, hepatocytes have been perceived as passive bystanders that allow hepatotropic pathogens such as Plasmodium to develop relatively unchallenged. However, now there is emerging evidence suggesting that hepatocytes can mount robust cell-autonomous immune responses that target Plasmodium, limiting its progression to the blood and reducing the incidence and severity of clinical malaria. Here we discuss our current understanding of hepatocyte cell-intrinsic immune responses that target Plasmodium and how these pathways impact malaria.

Effect of Shenlingyigan decoction on inflammatory factors related to liver injury regulated by TLR3 signaling pathway

Background

To investigate the therapeutic effect of Shenlingyigan decoction on acute liver injury. Further explored the mechanisms involved in the therapeutic properties of Shenlingyigan decoction by test several key proteins (TLR3, TRIF, TBK1, IRF3, IFNβ, IL-1 and IL-6) within the TLR3 signaling pathway.

Methods

The mouse acute liver injury model group was established by pretreatment with D-GalN and Poly (I:C) induction. The acute liver injury mouse treatment groups were gavage with different doses of Shenlingyigan decoction for 3 days. The therapeutic effects of Shenlingyigan decoction were preliminarily evaluated using organ indices, tissue images, and HE staining. Furthermore, potential associated signaling pathways and target effects were predicted through network pharmacology. Western blot experiments were conducted to examine the expression of relevant proteins (TLR3, TRIF, TBK1, IRF3, IL-1, and IL-6). In addition, immunofluorescence assays were performed to assess the localization of IRF3 and IFNβ expression in the cytoplasm and nucleus. Finally, the effects of Shenlingyigan decoction on the expression of TLR3, TRIF, TBK1 and IRF3 genes were further studied by QT-PCR.

Results

The liver organ index, the tissue photos and HE staining showed that Shenlingyigan decoction could reduce inflammation by decreasing the presence of inflammatory cells and downregulating the expression of IL-1 and IL-6. The result of network pharmacology showed 709 potential drug and disease overlapping targets. Toll-like receptor signaling pathway was related with these targets through KEGG analysis. Besides, TLR3, TBK1, IRF3, IL6, were important targets associated with viral hepatitis. Westernblot and Immunofluorescence analysis showed that Shenlingyigan decoction reduced the expression of TLR3 and TBK1 in mice with liver injury, while increasing the expression of IRF3. Shenlingyigan decoction does not significantly affect the expression of TRIF and IFNβ; however, it enhances the expression of IRF3 in the nucleus, consequently leading to increased expression of IFNβ in the nucleus. The results of QT-PCR showed that Shenlingyigan decoction could down-regulate the expression of TLR3, TRIF and TBK1 genes, and up-regulate the expression of IRF3 gene.

Conclusions

Shenlingyigan decoction participated in immune responses by effecting the expression of TLR3 signaling pathway-related factors to treat the acute liver injury.

Emerging roles of tyrosine kinases in hepatic inflammatory diseases and therapeutic opportunities

Inflammation has been convicted of causing and worsening many liver diseases like acute liver failure, fibrosis, cirrhosis, fatty liver and liver cancer. Pattern recognition receptors (PRRs) like TLRs 4 and 9 localized on resident or recruited immune cells are well known cellular detectors of pathogen and damage-associated molecular patterns (PAMPs/DAMPs). Stimulation of these receptors generates the sterile and non-sterile inflammatory responses in the liver. When these responses are repeated, there will be a sustained liver injury that may progress to fibrosis and its outcomes. Crosstalk between inflammatory/fibrogenic-dependent streams and certain tyrosine kinases (TKs) has recently evolved in the context of hepatic diseases. Because of TKs increasing importance, their role should be elucidated to highlight effective approaches to manage the diverse liver disorders. This review will give a brief overview of types and functions of some TKs like BTK, JAKs, Syk, PI3K, Src and c-Abl, as well as receptors for TAM, PDGF, EGF, VEGF and HGF. It will then move to discuss the roles of these TKs in the regulation of the proinflammatory, fibrogenic and tumorigenic responses in the liver. Lastly, the therapeutic opportunities for targeting TKs in hepatic inflammatory disorders will be addressed. Overall, this review sheds light on the diverse TKs that have substantial roles in hepatic disorders and potential therapeutics modulating their activity.

Omics are Getting Us Closer to Understanding IgA Nephropathy

During the last decade, thanks to omics technologies, new light has been shed on the pathogenesis of many diseases. Genomics, epigenomics, transcriptomics, and proteomics have helped to provide a better understanding of the origin and heterogeneity of several diseases. However, the risk factors for most autoimmune diseases remain unknown. The successes and pitfalls of omics have also been observed in nephrology, including immunoglobulin A nephropathy (IgAN), the most common form of glomerulonephritis and a principal cause of end-stage renal disease worldwide. Unfortunately, the immense progress in basic research has not yet been followed by the satisfactory development of a targeted treatment. Although, most omics studies describe changes in the immune system, there is still insufficient data to apply their results in the constantly evolving multi-hit pathogenesis model and thus do to provide a complete picture of the disease. Here, we describe recent findings regarding the pathophysiology of IgAN and link omics studies with immune system dysregulation. This review provides insights into specific IgAN markers, which may lead to the identification of potential targets for personalised treatment in the future.

Histone H3 activates caspase-1 and promotes proliferation and metastasis in hepatocellular carcinoma

Background: As a component of nucleosomes, histone H3 plays an important role in chromosome structure and gene expression. Current studies have mostly focused on the role of histones in epigenetics, but in addition to this, the role of histones themselves in tumor development and microenvironment have been less explored. Methods: Western blot and immunofluorescence were carried out to detect the content and localization of histone H3 in hepatocellular carcinoma. The changes of histone H3 were observed in hypoxia treatment cells, the specific action mechanism of histone H3 was studied by CoIP and other methods. Cell Counting Kit-8 assay, plate cloning assay and transwell assay were used to exam the effect of histone H3 on cell proliferation and metastasis, which were verified by subcutaneous tumors in mice and lung metastasis by tail vein injection in mice. Results: We found that histone H3 was overexpressed in hepatocellular carcinoma tumor tissues compared to adjacent non-tumor tissues, and there was concomitant translocation of histone H3 from the nucleus to the cytoplasm. We found that hypoxia could contribute to this phenomenon of histone H3 translocation from the nucleus to the cytoplasm in hepatocellular carcinoma cells and increased binding levels to TLR9. At the same time, hypoxia induced downstream activation of TLR9 and caspase-1, as well as cleavage and release of the pro-inflammatory cytokines IL-1β and IL-18. We further demonstrated that histone H3 could also promote proliferation and metastasis of hepatocellular carcinoma through TLR9 activation of NLRP3 inflammasome. In addition, overexpression of histone H3 was also confirmed to promote hepatocellular carcinoma proliferation and metastasis in mouse models of hepatocellular carcinoma growth assay and lung metastasis. Conclusions: In hypoxic hepatocellular carcinoma cells, histone H3 can translocate to the cytoplasm and activate caspase-1 via TLR9, thereby producing pro-inflammatory cytokines that promote tumor proliferation and metastasis.

Diet-induced gut dysbiosis and inflammation: Key drivers of obesity-driven NASH

Sucrose, the primary circulating sugar in plants, contains equal amounts of fructose and glucose. The latter is the predominant circulating sugar in animals and thus the primary fuel source for various tissue and cell types in the body. Chronic excessive energy intake has, however, emerged as a major driver of obesity and associated pathologies including nonalcoholic fatty liver diseases (NAFLD) and the more severe nonalcoholic steatohepatitis (NASH). Consumption of a high-caloric, western-style diet induces gut dysbiosis and inflammation resulting in leaky gut. Translocation of gut-derived bacterial content promotes hepatic inflammation and ER stress, and when either or both of these are combined with steatosis, it can cause NASH. Here, we review the metabolic links between diet-induced changes in the gut and NASH. Furthermore, therapeutic interventions for the treatment of obesity and liver metabolic diseases are also discussed with a focus on restoring the gut-liver axis.

TRIM25 inhibits spring viraemia of carp virus replication by positively regulating RIG-I signaling pathway in common carp (Cyprinus carpio L.)

Common carp (Cyprinus carpio L.) is one of the most widely cultivated fish in China. Spring viraemia of carp virus (SVCV) is a highly pathogenic virus and has often caused excessive losses in carp pond fisheries. Innate immune play important roles against virus infection. To better understand the immune response of common carp against SVCV infection, transcriptome analysis was performed using the Illumina Novaseq 6000 platform. It was showed that a total of 3953 differentially expressed unigenes were identified, and the RLR signaling pathway were significantly enriched after SVCV infection. Subsequently, the role of RLR signaling pathway in SVCV infection was studied. The results showed that common carp RIG-I (CcRIG-I) and TRIM25 (CcTRIM25) significantly decreased the replication of SVCV by inducing the phosphorylation of TBK1, IRF3 and p65 and the expression of ifn-1, viperin, isg15 and mx. Further studies illustrated that CcTRIM25 could positive regulate CcRIG-I mediated downstream signaling pathway. Finally, the mechanism of CcTRIM25 promoting CcRIG-I-mediated signaling was investigated. CcTRIM25 could interact with the caspase activation and recruitment domain (CARD) of CcRIG-I and promoted K63-linked polyubiquitination of CcRIG-I. Altogether, the study revealed a mechanism of CcTRIM25 regulating CcRIG-I mediated immune response in SVCV infection.

Gut microbiota alteration and modulation in hepatitis B virus-related fibrosis and complications: Molecular mechanisms and therapeutic inventions

Hepatitis B virus (HBV) has posed a threat to public health, mainly resulting in liver damage. With long-term accumulation of extracellular matrix, patients with chronic hepatitis B are at high risk of developing into liver fibrosis and cirrhosis and even life-threatening hepatic carcinoma. The occurrence of complications such as spontaneous bacterial peritonitis and hepatic encephalopathy greatly increases disability and mortality. With deeper understanding of the bidirectional interaction between the liver and the gut (gut-liver axis), there is a growing consensus that the human health closely relates to the gut microbiota. Supported by animal and human studies, the gut microbiota alters as the HBV-related liver fibrosis initials and progresses, characterized as the decrease of the ratio between “good” and “potentially pathogenic” microbes. When the primary disease is controlled via antiviral treatment, the gut microbiota dysfunction tends to be improved. Conversely, the recovery of gut microbiota can promote the regression of liver fibrosis. Therapeutic strategies targeted on gut microbiota (rifaximin, probiotics, engineered probiotics and fecal microbiota transplantation) have been applied to animal models and patients, obtaining satisfactory results.

Chlorogenic Acid Alleviates the Inflammatory Stress of LPS-Induced BV2 Cell via Interacting with TLR4-Mediated Downstream Pathway

Background

Neuroinflammation is related with the inflammatory stress of brain tissue induced by the activation of microglial in the central nervous system (CNS), which is still an intractable disease for modern clinical system. Chlorogenic acid has multiple biological activities such as antivirus and anti-inflammation, while few researches have revealed its therapeutic functions in neuroinflammation.

Methods

BV2 cells were treated with lipopolysaccharide (LPS) to establish neuroinflammation cell models, and the effects and mechanism of chlorogenic acid in improving the inflammatory progression were investigated. In brief, the toxicity of chlorogenic acid on BV2 cells was detected with MTT assay. The levels of the inflammatory factors including TNF-α, IL-6, IL-1β, and IFN-α were measured with ELISA, and the abundances of TLR4, MyD88, TRIF, and NF-κB were observed by qRT-PCR and western blot.

Results

Chlorogenic acid did not exhibit obvious toxic and side effects on BV2 cells. The levels of TNF-α, IL-6, IL-1β, and IFN-α were observably upregulated in BV2 cells after treating with LPS. Chlorogenic acid significantly reduced the levels of TNF-α, IL-6, IL-1β, and IFN-α. Moreover, the abundances of TLR4, MyD88, TRIF, and NF-κB were increased in LPS-induced BV2 cells, while chlorogenic acid could obviously reduce their expressions.

Conclusion

This study suggests that chlorogenic acid can improve the inflammatory stress of LPS-induced BV2 cell via interacting with the TLR4-mediated downstream pathway, which is a potential drug for neuroinflammation treatment.

IL28B, TLR7 SNPs, and cytomegalovirus infection are risk factors for advanced liver disease in chronic hepatitis C patients

BACKGROUND

Chronic hepatitis C (CHC) is a leading cause of cirrhosis and hepatocellular carcinoma (HCC). This study aimed to study the association of IL28B, toll-like receptor (TLR) 7, cytomegalovirus and advanced liver disease.

METHODS

Four groups were included; control (n = 125, 25.9%), CHC (n = 114, 23.6%), liver cirrhosis (n = 120, 24.8%), and HCC (n = 124, 25.7%).

RESULTS

In CHC group, patients were mainly F1 (60%) followed by F2. IL28B genotype CC percentage was higher in control group than the CHC and cirrhosis groups. CT and TT genotypes were higher in the CHC and cirrhosis groups than control group. The C allele was higher in the control group than the CHC, cirrhosis and HCC groups and the opposite with the T allele. Control and CHC had same TLR7 alleles. Cirrhosis patients and HCC had lower TLR 7 A allele and higher G allele than the control group. Both cirrhosis and HCC groups had statistically significant higher percentage of the AG and GG genotypes than the control group. Patients with HCC had higher cytomegalovirus infection percentage than cirrhosis and CHC group (38.7% vs 20% vs 16.7%), respectively.

CONCLUSION

IL28B, TLR7 SNPs and cytomegalovirus infection are risk factors for advanced liver disease in hepatitis C patients.

Toll-like receptors and hepatitis C virus infection

BACKGROUND

Hepatitis C virus (HCV) infection is a worldwide issue. However, the current treatment for hepatitis C has many shortcomings. Toll-like receptors (TLRs) are pattern recognition receptors involved in HCV infection, and an increasing number of studies are focusing on the role of TLRs in the progression of hepatitis C.

DATA SOURCES

We performed a PubMed search up to January 2021 with the following keywords: hepatitis C, toll-like receptors, interferons, inflammation, and immune evasion. We also used terms such as single-nucleotide polymorphisms (SNPs), susceptibility, fibrosis, cirrhosis, direct-acting antiviral agents, agonists, and antagonists to supplement the query results. We reviewed relevant publications analyzing the correlation between hepatitis C and TLRs and the role of TLRs in HCV infection.

RESULTS

TLRs 1-4 and 6-9 are involved in the process of HCV infection. When the host is exposed to the HCV, TLRs, as important participants in HCV immune evasion, trigger innate immunity to remove the virus and also promote inflammation and liver fibrosis. TLR gene SNPs affect hepatitis C susceptibility, treatment, and prognosis. The contribution of each TLR to HCV is different. Drugs targeting various TLRs are developed and validated, and TLRs can synergize with classic hepatitis C drugs, including interferon and direct-acting antiviral agents, constituting a new direction for the treatment of hepatitis C.

CONCLUSIONS

TLRs are important receptors in HCV infection. Different TLRs induce different mechanisms of virus clearance and inflammatory response. Although TLR-related antiviral therapy strategies exist, more studies are needed to explore the clinical application of TLR-related drugs.

Targeting Gut–Liver Axis for Treatment of Liver Fibrosis and Portal Hypertension

Antifibrotic therapies for the treatment of liver fibrosis represent an unconquered area of drug development. The significant involvement of the gut microbiota as a driving force in a multitude of liver disease, be it pathogenesis or fibrotic progression, suggest that targeting the gut–liver axis, relevant signaling pathways, and/or manipulation of the gut’s commensal microbial composition and its metabolites may offer opportunities for biomarker discovery, novel therapies and personalized medicine development. Here, we review potential links between bacterial translocation and deficits of host-microbiome compartmentalization and liver fibrosis that occur in settings of advanced chronic liver disease. We discuss established and emerging therapeutic strategies, translated from our current knowledge of the gut–liver axis, targeted at restoring intestinal eubiosis, ameliorating hepatic fibrosis and rising portal hypertension that characterize and define the course of decompensated cirrhosis.

Multi-Modal Fusion Emotion Recognition Method of Speech Expression Based on Deep Learning

The redundant information, noise data generated in the process of single-modal feature extraction, and traditional learning algorithms are difficult to obtain ideal recognition performance. A multi-modal fusion emotion recognition method for speech expressions based on deep learning is proposed. Firstly, the corresponding feature extraction methods are set up for different single modalities. Among them, the voice uses the convolutional neural network-long and short term memory (CNN-LSTM) network, and the facial expression in the video uses the Inception-Res Net-v2 network to extract the feature data. Then, long and short term memory (LSTM) is used to capture the correlation between different modalities and within the modalities. After the feature selection process of the chi-square test, the single modalities are spliced to obtain a unified fusion feature. Finally, the fusion data features output by LSTM are used as the input of the classifier LIBSVM to realize the final emotion recognition. The experimental results show that the recognition accuracy of the proposed method on the MOSI and MELD datasets are 87.56 and 90.06%, respectively, which are better than other comparison methods. It has laid a certain theoretical foundation for the application of multimodal fusion in emotion recognition.

Identification and functional characterization of a fish-specific tlr19 in common carp (Cyprinus carpio L.) that recruits TRIF as an adaptor and induces ifn expression during the immune response

Toll-like receptor 19 (Tlr19) is a fish-specific TLR that plays a critical role in innate immunity. In the present study, we aimed to identify tlr19 from common carp (Cyprinus carpio L.) and explored its expression profile, localization, adaptor, and signaling pathways. A novel tlr19 cDNA sequence (Cctlr19) was identified in common carp. Phylogenetic analysis revealed that CcTlr19 was most closely related to Danio rerio Tlr19. Subcellular localization analysis indicates that CcTlr19 was synthesized in the free ribosome and then transported to early endosomes. Cctlr19 was constitutively expressed in all the examined tissues, with the highest expression in the brain. After poly(I:C) and Aeromonas hydrophila injection, the expression of Cctlr19 was significantly upregulated in immune-related organs. In addition, the expression of Cctlr19 was upregulated in head kidney leukocytes (HKL) upon stimulation with different ligands. Immunofluorescence and luciferase analyses indicate that CcTlr19 recruited TRIF as an adaptor. Furthermore, CcTlr19 can activate the expression of ifn-1 and viperin. Taken together, these findings lay the foundation for future research to investigate the mechanisms underlying fish tlr19.

Tumor Immune Microenvironment and Immunosuppressive Therapy in Hepatocellular Carcinoma: A Review

Liver cancer has the fourth highest mortality rate of all cancers worldwide, with hepatocellular carcinoma (HCC) being the most prevalent subtype. Despite great advances in systemic therapy, such as molecular-targeted agents, HCC has one of the worst prognoses due to drug resistance and frequent recurrence and metastasis. Recently, new therapeutic strategies such as cancer immunosuppressive therapy have prolonged patients' lives, and the combination of an immune checkpoint inhibitor (ICI) and VEGF inhibitor is now positioned as the first-line therapy for advanced HCC. Since the efficacy of ICIs depends on the tumor immune microenvironment, it is necessary to elucidate the immune environment of HCC to select appropriate ICIs. In this review, we summarize the findings on the immune microenvironment and immunosuppressive approaches focused on monoclonal antibodies against cytotoxic T lymphocyte-associated protein 4 and programmed cell death protein 1 for HCC. We also describe ongoing treatment modalities, including adoptive cell transfer-based therapies and future areas of exploration based on recent literature. The results of pre-clinical studies using immunological classification and animal models will contribute to the development of biomarkers that predict the efficacy of immunosuppressive therapy and aid in the selection of appropriate strategies for HCC treatment.