Identification of a role for TRIM29 in the control of innate immunity in the respiratory tract

Role of TRIM29 in disease: What is and is not known

Tripartite motif-containing proteins (TRIMs), comprising the greatest subfamily of E3 ubiquitin ligases with approximately 80 members of this family, are widely distributed in mammalian cells. TRIMs actively participate in ubiquitination of target proteins, a type of post-translational modification associated with protein degradation and other functions. Tripartite motif-containing protein 29 (TRIM29), a member of the TRIM family, differs from other members of this family in that it lacks the RING finger structural domain containing cysteine and histidine residues that mediates DNA binding, protein-protein interactions, and ubiquitin ligase, at its N-terminus. The expression of TRIM29 was initially found to be associated with cancer and diabetic nephropathy progression, and antiviral immunity which is triggered by virus-derived nucleic acids binding to pattern recognition receptors (PRRs) on immune cells. Recently, TRIM29 has also been explored as a diagnostic biomarker and therapeutic target for some immune-related diseases. Here, we review the functions of TRIM29 in the progression of diseases and the inherent mechanisms, as well as the remaining gaps in the literature. A thorough understanding of the detailed regulatory mechanisms of TRIM29 will ultimately facilitate the development of different therapeutic strategies for various diseases.

When animal viruses meet N6-methyladenosine (m6A) modifications: for better or worse?

N6-methyladenosine (m6A) is a prevalent and dynamic RNA modification, critical in regulating gene expression. Recent research has shed light on its significance in the life cycle of viruses, especially animal viruses. Depending on the context, these modifications can either enhance or inhibit the replication of viruses. However, research on m6A modifications in animal virus genomes and the impact of viral infection on the host cell m6A landscape has been hindered due to the difficulty of detecting m6A sites at a single-nucleotide level. This article summarises the methods for detecting m6A in RNA. It then discusses the progress of research into m6A modification within animal viruses' infections, such as influenza A virus, porcine epidemic diarrhoea virus, porcine reproductive, and respiratory syndrome virus. Finally, the review explores how m6A modification affects the following three aspects of the replication of animal RNA viruses: the regulation of viral genomic RNA function, the alteration of the m6A landscape in cells after viral infection, and the modulation of antiviral immunity through m6A modification. Research on m6A modifications in viral RNA sheds light on virus-host interactions at a molecular level. Understanding the impact of m6A on viral replication can help identify new targets for antiviral drug development and may uncover novel regulatory pathways that could potentially enhance antiviral immune responses.

Metabolism: a potential regulator of neutrophil fate

Neutrophils are essential components of the innate immune system that defend against the invading pathogens, such as bacteria, viruses, and fungi, as well as having regulatory roles in various conditions, including tissue repair, cancer immunity, and inflammation modulation. The function of neutrophils is strongly related to their mode of cell death, as different types of cell death involve various cellular and molecular alterations. Apoptosis, a non-inflammatory and programmed type of cell death, is the most common in neutrophils, while other modes of cell death, including NETOsis, necrosis, necroptosis, autophagy, pyroptosis, and ferroptosis, have specific roles in neutrophil function regulation. Immunometabolism refers to energy and substance metabolism in immune cells, and profoundly influences immune cell fate and immune system function. Intercellular and intracellular signal transduction modulate neutrophil metabolism, which can, in turn, alter their activities by influencing various cell signaling pathways. In this review, we compile an extensive body of evidence demonstrating the role of neutrophil metabolism in their various forms of cell death. The review highlights the intricate metabolic characteristics of neutrophils and their interplay with various types of cell death.

Human airway epithelium controls Pseudomonas aeruginosa infection via inducible nitric oxide synthase

Introduction

Airway epithelial cells play a central role in the innate immune response to invading bacteria, yet adequate human infection models are lacking.

Methods

We utilized mucociliary-differentiated human airway organoids with direct access to the apical side of epithelial cells to model the initial phase of Pseudomonas aeruginosa respiratory tract infection.

Results

Immunofluorescence of infected organoids revealed that Pseudomonas aeruginosa invades the epithelial barrier and subsequently proliferates within the epithelial space. RNA sequencing analysis demonstrated that Pseudomonas infection stimulated innate antimicrobial immune responses, but specifically enhanced the expression of genes of the nitric oxide metabolic pathway. We demonstrated that activation of inducible nitric oxide synthase (iNOS) in airway organoids exposed bacteria to nitrosative stress, effectively inhibiting intra-epithelial pathogen proliferation. Pharmacological inhibition of iNOS resulted in expansion of bacterial proliferation whereas a NO producing drug reduced bacterial numbers. iNOS expression was mainly localized to ciliated epithelial cells of infected airway organoids, which was confirmed in primary human lung tissue during Pseudomonas pneumonia.

Discussion

Our findings highlight the critical role of epithelial-derived iNOS in host defence against Pseudomonas aeruginosa infection. Furthermore, we describe a human tissue model that accurately mimics the airway epithelium, providing a valuable framework for systemically studying host-pathogen interactions in respiratory infections.

The crosstalk between DNA-damage responses and innate immunity

DNA damage is typically caused during cell growth by DNA replication stress or exposure to endogenous or external toxins. The accumulation of damaged DNA causes genomic instability, which is the root cause of many serious disorders. Multiple cellular organisms utilize sophisticated signaling pathways against DNA damage, collectively known as DNA damage response (DDR) networks. Innate immune responses are activated following cellular abnormalities, including DNA damage. Interestingly, recent studies have indicated that there is an intimate relationship between the DDR network and innate immune responses. Diverse kinds of cytosolic DNA sensors, such as cGAS and STING, recognize damaged DNA and induce signals related to innate immune responses, which link defective DDR to innate immunity. Moreover, DDR components operate in immune signaling pathways to induce IFNs and/or a cascade of inflammatory cytokines via direct interactions with innate immune modulators. Consistently, defective DDR factors exacerbate the innate immune imbalance, resulting in severe diseases, including autoimmune disorders and tumorigenesis. Here, the latest progress in understanding crosstalk between the DDR network and innate immune responses is reviewed. Notably, the dual function of innate immune modulators in the DDR network may provide novel insights into understanding and developing targeted immunotherapies for DNA damage-related diseases, even carcinomas.

Deciphering the potential role of post-translational modifications of histones in gastrointestinal cancers: a proteomics-based review with therapeutic challenges and opportunities

Oncogenesis is a complex and multi-step process, controlled by several factors including epigenetic modifications. It is considered that histone modifications are critical components in the regulation of gene expression, protein functions, and molecular interactions. Dysregulated post-translationally modified histones and the related enzymatic systems are key players in the control of cell proliferation and differentiation, which are associated with the onset and progression of cancers. The most of traditional investigations on cancer have focused on mutations of oncogenes and tumor suppressor genes. However, increasing evidence indicates that epigenetics, especially histone post-translational modifications (PTMs) play important roles in various cancer types. Mass spectrometry-based proteomic approaches have demonstrated tremendous potential in PTMs profiling and quantitation in different biological systems. In this paper, we have made a proteomics-based review on the role of histone modifications involved in gastrointestinal cancers (GCs) tumorigenesis processes. These alterations function not only as diagnostic or prognostic biomarkers for GCs, but a deeper comprehension of the epigenetic regulation of GCs could facilitate the treatment of this prevalent malignancy through the creation of more effective targeted therapies.

Divergent sensory pathways of sneezing and coughing

Sneezing and coughing are primary symptoms of many respiratory viral infections and allergies. It is generally assumed that sneezing and coughing involve common sensory receptors and molecular neurotransmission mechanisms. Here, we show that the nasal mucosa is innervated by several discrete populations of sensory neurons, but only one population (MrgprC11+MrgprA3-) mediates sneezing responses to a multitude of nasal irritants, allergens, and viruses. Although this population also innervates the trachea, it does not mediate coughing, as revealed by our newly established cough model. Instead, a distinct sensory population (somatostatin [SST+]) mediates coughing but not sneezing, unraveling an unforeseen sensory difference between sneezing and coughing. At the circuit level, sneeze and cough signals are transmitted and modulated by divergent neuropathways. Together, our study reveals the difference in sensory receptors and neurotransmission/modulation mechanisms between sneezing and coughing, offering neuronal drug targets for symptom management in respiratory viral infections and allergies.

TRIM29 controls enteric RNA virus-induced intestinal inflammation by targeting NLRP6 and NLRP9b signaling pathways

Infections by enteric virus and intestinal inflammation are recognized as a leading cause of deadly gastroenteritis, and NLRP6 and NLRP9b signaling control these infection and inflammation. However, the regulatory mechanisms of the NLRP6 and NLRP9b signaling in enteric viral infection remain unexplored. In this study, we found that the E3 ligase TRIM29 suppressed type III interferon (IFN-λ) and interleukin-18 (IL-18) production by intestinal epithelial cells (IECs) when exposed to polyinosinic:polycytidylic acid (poly I:C) and enteric RNA viruses. Knockout of TRIM29 in IECs was efficient to restrict intestinal inflammation triggered by the enteric RNA viruses, rotavirus in suckling mice, and the encephalomyocarditis virus (EMCV) in adults. This attenuation in inflammation was attributed to the increased production of IFN-λ and IL-18 in the IECs and more recruitment of intraepithelial protective Ly6A+CCR9+CD4+ T cells in small intestines from TRIM29-deficient mice. Mechanistically, TRIM29 promoted K48-linked ubiquitination, leading to the degradation of NLRP6 and NLRP9b, resulting in decreased IFN-λ and IL-18 secretion by IECs. Our findings reveal that enteric viruses utilize TRIM29 to inhibit IFN-λ and inflammasome activation in IECs, thereby facilitating viral-induced intestinal inflammation. This indicates that targeting TRIM29 could offer a promising therapeutic strategy for alleviating gut diseases.

Extracellular vesicles from a novel Lactiplantibacillus plantarum strain suppress inflammation and promote M2 macrophage polarization

Background

Lactiplantibacillus plantarum (L. plantarum) is known for its probiotic properties, including antioxidant and anti-inflammatory effects. Recent studies have highlighted the role of extracellular vesicles (EVs) from prokaryotic cells in anti-inflammatory effects.

Objective

This study aims to investigate the anti-inflammatory effects of extracellular vesicles derived from a newly isolated strain of L. plantarum (LP25 strain) and their role in macrophage polarization.

Methods

The LP25 strain and its extracellular vesicles were isolated and identified through genomic sequencing, transmission electron microscopy (TEM), and nanoparticle tracking analysis (NTA). RAW 264.7 cells were treated with lipopolysaccharide (LPS) and/or LP25-derived extracellular vesicles (LEV). Morphological changes in the cells were observed, and the expression levels of pro-inflammatory cytokines (TNF-α, IL-6)、iNOS and anti-inflammatory cytokines (IL-10) 、Arg-1 were measured using quantitative real-time PCR (qPCR). Flow cytometry was used to detect the expression of Arg-1 in the treated cells.

Results

Treatment with LP25 EVs led to significant morphological changes in RAW 264.7 cells exposed to LPS. LP25 EVs treatment resulted in increased expression of Arg-1 and anti-inflammatory cytokines IL-10, and decreased expression of iNOS and surface markers protein CD86. Flow cytometry confirmed the increased expression of the M2 macrophage marker Arg-1 in the LP25 EVs-treated group.

Conclusion

Extracellular vesicles from Lactiplantibacillus plantarum LP25 can suppress inflammatory responses and promote the polarization of macrophages toward the anti-inflammatory M2 phenotype. These findings provide new evidence supporting the anti-inflammatory activity of L. plantarum-derived EVs.

Macrophage polarization and its impact on idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a lung disease that worsens over time, causing fibrosis in the lungs and ultimately resulting in respiratory failure and a high risk of death. Macrophages play a crucial role in the immune system, showing flexibility by transforming into either pro-inflammatory (M1) or anti-inflammatory (M2) macrophages when exposed to different stimuli, ultimately impacting the development of IPF. Recent research has indicated that the polarization of macrophages is crucial in the onset and progression of IPF. M1 macrophages secrete inflammatory cytokines and agents causing early lung damage and fibrosis, while M2 macrophages support tissue healing and fibrosis by releasing anti-inflammatory cytokines. Developing novel treatments for IPF relies on a thorough comprehension of the processes involved in macrophage polarization in IPF. The review outlines the regulation of macrophage polarization and its impact on the development of IPF, with the goal of investigating the possible therapeutic benefits of macrophage polarization in the advancement of IPF.

Exploring TRIM proteins' role in antiviral defense against influenza A virus and respiratory coronaviruses

Numerous tripartite motif (TRIM) proteins, identified as E3 ubiquitin ligases, participate in various viral infections through ubiquitylation, ISGylation, and SUMOylation processes. Respiratory viruses, particularly influenza A virus (IAV) and respiratory coronaviruses (CoVs), have severely threatened public health with high morbidity and mortality, causing incalculable losses. Research on the regulation of TRIM proteins in respiratory virus infections is crucial for disease prevention and control. This review introduces TRIM proteins, summarizes recent discoveries regarding their roles and molecular mechanisms in IAV and CoVs infections, discusses current research gaps, and explores potential future trends in this rapidly developing field. It aims to enhance understanding of virus-host interactions and inform the development of new molecularly targeted therapies.

An investigation of the molecular characterization of the tripartite motif (TRIM) family and primary validation of TRIM31 in gastric cancer

Most TRIM family members characterized by the E3-ubiquitin ligases, participate in ubiquitination and tumorigenesis. While there is a dearth of a comprehensive investigation for the entire family in gastric cancer (GC). By combining the TCGA and GEO databases, common TRIM family members (TRIMs) were obtained to investigate gene expression, gene mutations, and clinical prognosis. On the basis of TRIMs, a consensus clustering analysis was conducted, and a risk assessment system and prognostic model were developed. Particularly, TRIM31 with clinical prognostic and diagnostic value was chosen for single-gene bioinformatics analysis, in vitro experimental validation, and immunohistochemical analysis of clinical tissue microarrays. The combined dataset consisted of 66 TRIMs, of which 52 were differentially expressed and 43 were differentially prognostic. Significant survival differences existed between the gene clusters obtained by consensus clustering analysis. Using 4 differentially expressed genes identified by multivariate Cox regression and LASSO regression, a risk scoring system was developed. Higher risk scores were associated with a poorer prognosis, suppressive immune cell infiltration, and drug resistance. Transcriptomic data and clinical sample tissue microarrays confirmed that TRIM31 was highly expressed in GC and associated with a poor prognosis. Pathway enrichment analysis, cell migration and colony formation assay, EdU assay, reactive oxygen species (ROS) assay, and mitochondrial membrane potential assay revealed that TRIM31 may be implicated in cell cycle regulation and oxidative stress-related pathways, contribute to gastric carcinogenesis. This study investigated the whole functional and expression profile and a risk score system based on the TRIM family in GC. Further investigation centered around TRIM31 offers insight into the underlying mechanisms of action exhibited by other members of its family in the context of GC.

Multi-Directional Mechanisms of Participation of the TRIM Gene Family in Response of Innate Immune System to Bacterial Infections

The multigene TRIM family is an important component of the innate immune system. For a long time, the main function of the genes belonging to this family was believed to be an antiviral defense of the host organism. The issue of their participation in the immune system response to bacterial invasion has been less studied. This review is the first comprehensive analysis of the mechanisms of functioning of the TRIM family genes in response to bacterial infections, which expands our knowledge about the role of TRIM in the innate immune system. When infected with different types of bacteria, individual TRIM proteins regulate inflammatory, interferon, and other responses of the immune system in the cells, and also affect autophagy and apoptosis. Functioning of TRIM proteins in response to bacterial infection, as well as viral infection, often includes ubiquitination and various protein-protein interactions with both bacterial proteins and host cell proteins. At the same time, some TRIM proteins, on the contrary, contribute to the infection development. Different members of the TRIM family possess similar mechanisms of response to viral and bacterial infection, and the final impact of these proteins could vary significantly. New data on the effect of TRIM proteins on bacterial infections make an important contribution to a more detailed understanding of the innate immune system functioning in animals and humans when interacting with pathogens. This data could also be used for the search of new targets for antibacterial defense.

The "root" causes behind the anti-inflammatory actions of ginger compounds in immune cells

Ginger (Zingiber officinale) is one of the most well-known spices and medicinal plants worldwide that has been used since ancient times to treat a plethora of diseases including cold, gastrointestinal complaints, nausea, and migraine. Beyond that, a growing body of literature demonstrates that ginger exhibits anti-inflammatory, antioxidant, anti-cancer and neuroprotective actions as well. The beneficial effects of ginger can be attributed to the biologically active compounds of its rhizome such as gingerols, shogaols, zingerone and paradols. Among these compounds, gingerols are the most abundant in fresh roots, and shogaols are the major phenolic compounds of dried ginger. Over the last two decades numerous in vitro and in vivo studies demonstrated that the major ginger phenolics are able to influence the function of various immune cells including macrophages, neutrophils, dendritic cells and T cells. Although the mechanism of action of these compounds is not fully elucidated yet, some studies provide a mechanistic insight into their anti-inflammatory effects by showing that ginger constituents are able to target multiple signaling pathways. In the first part of this review, we summarized the current literature about the immunomodulatory actions of the major ginger compounds, and in the second part, we focused on the possible molecular mechanisms that may underlie their anti-inflammatory effects.

The Male Reproductive Toxicity Caused by 2-Naphthylamine Was Related to Testicular Immunity Disorders

2-naphthylamine (NAP) was classified as a group I carcinogen associated with bladder cancer. The daily exposure is mostly from cigarette and E-cigarette smoke. NAP can lead to testicular atrophy and interstitial tissue hyperplasia; however, the outcomes of NAP treatment on spermatogenesis and the associated mechanisms have not been reported. The study aimed to investigate the effect of NAP on spermatogenesis and sperm physiologic functions after being persistently exposed to NAP at 5, 20, and 40 mg/kg for 35 days. We found that sperm motility, progressive motility, sperm average path velocity, and straight-line velocity declined remarkably in the NAP (40 mg/kg) treated group, and the sperm deformation rate rose upon NAP administration. The testis immunity- and lipid metabolism-associated processes were enriched from RNA-sequence profiling. Plvap, Ccr7, Foxn1, Trim29, Sirpb1c, Cfd, and Lpar4 involved in testis immunity and Pnliprp1 that inhibit triglyceride and cholesterol absorption were confirmed to rise dramatically in the NAP-exposed group. The increased total cholesterol and CD68 levels were observed in the testis from the NAP-exposed group. Gpx5, serving as an antioxidant in sperm plasma, and Semg1, which contributes to sperm progressive motility, were both down-regulated. We concluded that the short-term exposure to NAP caused reproductive toxicity, primarily due to the inflammatory abnormality in the testis.

Loss of TRIM29 mitigates viral myocarditis by attenuating PERK-driven ER stress response in male mice

Viral myocarditis, an inflammatory disease of the myocardium, is a significant cause of sudden death in children and young adults. The current coronavirus disease 19 pandemic emphasizes the need to understand the pathogenesis mechanisms and potential treatment strategies for viral myocarditis. Here, we found that TRIM29 was highly induced by cardiotropic viruses and promoted protein kinase RNA-like endoplasmic reticulum kinase (PERK)-mediated endoplasmic reticulum (ER) stress, apoptosis, and reactive oxygen species (ROS) responses that promote viral replication in cardiomyocytes in vitro. TRIM29 deficiency protected mice from viral myocarditis by promoting cardiac antiviral functions and reducing PERK-mediated inflammation and immunosuppressive monocytic myeloid-derived suppressor cells (mMDSC) in vivo. Mechanistically, TRIM29 interacted with PERK to promote SUMOylation of PERK to maintain its stability, thereby promoting PERK-mediated signaling pathways. Finally, we demonstrated that the PERK inhibitor GSK2656157 mitigated viral myocarditis by disrupting the TRIM29-PERK connection, thereby bolstering cardiac function, enhancing cardiac antiviral responses, and curbing inflammation and immunosuppressive mMDSC in vivo. Our findings offer insight into how cardiotropic viruses exploit TRIM29-regulated PERK signaling pathways to instigate viral myocarditis, suggesting that targeting the TRIM29-PERK axis could mitigate disease severity.

When DNA-damage responses meet innate and adaptive immunity

When cells proliferate, stress on DNA replication or exposure to endogenous or external insults frequently results in DNA damage. DNA-Damage Response (DDR) networks are complex signaling pathways used by multicellular organisms to prevent DNA damage. Depending on the type of broken DNA, the various pathways, Base-Excision Repair (BER), Nucleotide Excision Repair (NER), Mismatch Repair (MMR), Homologous Recombination (HR), Non-Homologous End-Joining (NHEJ), Interstrand Crosslink (ICL) repair, and other direct repair pathways, can be activated separately or in combination to repair DNA damage. To preserve homeostasis, innate and adaptive immune responses are effective defenses against endogenous mutation or invasion by external pathogens. It is interesting to note that new research keeps showing how closely DDR components and the immune system are related. DDR and immunological response are linked by immune effectors such as the cyclic GMP-AMP synthase (cGAS)-Stimulator of Interferon Genes (STING) pathway. These effectors act as sensors of DNA damage-caused immune response. Furthermore, DDR components themselves function in immune responses to trigger the generation of inflammatory cytokines in a cascade or even trigger programmed cell death. Defective DDR components are known to disrupt genomic stability and compromise immunological responses, aggravating immune imbalance and leading to serious diseases such as cancer and autoimmune disorders. This study examines the most recent developments in the interaction between DDR elements and immunological responses. The DDR network's immune modulators' dual roles may offer new perspectives on treating infectious disorders linked to DNA damage, including cancer, and on the development of target immunotherapy.

TP63-TRIM29 axis regulates enhancer methylation and chromosomal instability in prostate cancer

BACKGROUND

Prostate adenocarcinoma (PRAD) is the second leading cause of cancer-related deaths in men. High variability in DNA methylation and a high rate of large genomic rearrangements are often observed in PRAD.

RESULTS

To investigate the reasons for such high variance, we integrated DNA methylation, RNA-seq, and copy number alterations datasets from The Cancer Genome Atlas (TCGA), focusing on PRAD, and employed weighted gene co-expression network analysis (WGCNA). Our results show that only single cluster of co-expressed genes is associated with genomic and epigenomic instability. Within this cluster, TP63 and TRIM29 are key transcription regulators and are downregulated in PRAD. We discovered that TP63 regulates the level of enhancer methylation in prostate basal epithelial cells. TRIM29 forms a complex with TP63 and together regulates the expression of genes specific to the prostate basal epithelium. In addition, TRIM29 binds DNA repair proteins and prevents the formation of the TMPRSS2:ERG gene fusion typically observed in PRAD.

CONCLUSION

Our study demonstrates that TRIM29 and TP63 are important regulators in maintaining the identity of the basal epithelium under physiological conditions. Furthermore, we uncover the role of TRIM29 in PRAD development.

Analysis of single nuclear chromatin accessibility reveals unique myeloid populations in human pancreatic ductal adenocarcinoma

BACKGROUND

A better understanding of the pancreatic ductal adenocarcinoma (PDAC) immune microenvironment is critical to developing new treatments and improving outcomes. Myeloid cells are of particular importance for PDAC progression; however, the presence of heterogenous subsets with different ontogeny and impact, along with some fluidity between them, (infiltrating monocytes vs. tissue-resident macrophages; M1 vs. M2) makes characterisation of myeloid populations challenging. Recent advances in single cell sequencing technology provide tools for characterisation of immune cell infiltrates, and open chromatin provides source and function data for myeloid cells to assist in more comprehensive characterisation. Thus, we explore single nuclear assay for transposase accessible chromatin (ATAC) sequencing (snATAC-Seq), a method to analyse open gene promoters and transcription factor binding, as an important means for discerning the myeloid composition in human PDAC tumours.

METHODS

Frozen pancreatic tissues (benign or PDAC) were prepared for snATAC-Seq using 10× Chromium technology. Signac was used for preliminary analysis, clustering and differentially accessible chromatin region identification. The genes annotated in promoter regions were used for Gene Ontology (GO) enrichment and cell type annotation. Gene signatures were used for survival analysis with The Cancer Genome Atlas (TCGA)-pancreatic adenocarcinoma (PAAD) dataset.

RESULTS

Myeloid cell transcription factor activities were higher in tumour than benign pancreatic samples, enabling us to further stratify tumour myeloid populations. Subcluster analysis revealed eight distinct myeloid populations. GO enrichment demonstrated unique functions for myeloid populations, including interleukin-1b signalling (recruited monocytes) and intracellular protein transport (dendritic cells). The identified gene signature for dendritic cells influenced survival (hazard ratio = .63, p = .03) in the TCGA-PAAD dataset, which was unique to PDAC.

CONCLUSIONS

These data suggest snATAC-Seq as a method for analysis of frozen human pancreatic tissues to distinguish myeloid populations. An improved understanding of myeloid cell heterogeneity and function is important for developing new treatment targets in PDAC.

Biology of Pellino1: a potential therapeutic target for inflammation in diseases and cancers

Pellino1 (Peli1) is a highly conserved E3 Ub ligase that exerts its biological functions by mediating target protein ubiquitination. Extensive evidence has demonstrated the crucial role of Peli1 in regulating inflammation by modulating various receptor signaling pathways, including interleukin-1 receptors, Toll-like receptors, nuclear factor-κB, mitogen-activated protein kinase, and phosphoinositide 3-kinase/AKT pathways. Peli1 has been implicated in the development of several diseases by influencing inflammation, apoptosis, necrosis, pyroptosis, autophagy, DNA damage repair, and glycolysis. Peli1 is a risk factor for most cancers, including breast cancer, lung cancer, and lymphoma. Conversely, Peli1 protects against herpes simplex virus infection, systemic lupus erythematosus, esophageal cancer, and toxic epidermolysis bullosa. Therefore, Peli1 is a potential therapeutic target that warrants further investigation. This comprehensive review summarizes the target proteins of Peli1, delineates their involvement in major signaling pathways and biological processes, explores their role in diseases, and discusses the potential clinical applications of Peli1-targeted therapy, highlighting the therapeutic prospects of Peli1 in various diseases.

Intricate confrontation: Research progress and application potential of TRIM family proteins in tumor immune escape

BACKGROUND

Tripartite motif (TRIM) family proteins have more than 80 members and are widely found in various eukaryotic cells. Most TRIM family proteins participate in the ubiquitin-proteasome degradation system as E3-ubiquitin ligases; therefore, they play pivotal regulatory roles in the occurrence and development of tumors, including tumor immune escape. Due to the diversity of functional domains of TRIM family proteins, they can extensively participate in multiple signaling pathways of tumor immune escape through different substrates. In current research and clinical contexts, immune escape has become an urgent problem. The extensive participation of TRIM family proteins in curing tumors or preventing postoperative recurrence and metastasis makes them promising targets.

AIM OF REVIEW

The aim of the review is to make up for the gap in the current research on TRIM family proteins and tumor immune escape and propose future development directions according to the current progress and problems.

KEY SCIENTIFIC CONCEPTS OF REVIEW

This up-to-date review summarizes the characteristics and biological functions of TRIM family proteins, discusses the mechanisms of TRIM family proteins involved in tumor immune escape, and highlights the specific mechanism from the level of structure-function-molecule-pathway-phenotype, including mechanisms at the level of protein domains and functions, at the level of molecules and signaling pathways, and at the level of cells and microenvironments. We also discuss the application potential of TRIM family proteins in tumor immunotherapy, such as possible treatment strategies for combination targeting TRIM family protein drugs and checkpoint inhibitors for improving cancer treatment.

Deciphering roles of TRIMs as promising targets in hepatocellular carcinoma: current advances and future directions

Tripartite motif (TRIM) family is assigned to RING-finger-containing ligases harboring the largest number of proteins in E3 ubiquitin ligating enzymes. E3 ubiquitin ligases target the specific substrate for proteasomal degradation via the ubiquitin-proteasome system (UPS), which seems to be a more effective and direct strategy for tumor therapy. Recent advances have demonstrated that TRIM genes associate with the occurrence and progression of hepatocellular carcinoma (HCC). TRIMs trigger or inhibit multiple biological activities like proliferation, apoptosis, metastasis, ferroptosis and autophagy in HCC dependent on its highly conserved yet diverse structures. Remarkably, autophagy is another proteolytic pathway for intracellular protein degradation and TRIM proteins may help to delineate the interaction between the two proteolytic systems. In depth research on the precise molecular mechanisms of TRIM family will allow for targeting TRIM in HCC treatment. We also highlight several potential directions warranted further development associated with TRIM family to provide bright insight into its translational values in hepatocellular carcinoma.

Single cell transcriptomics reveals cell type specific features of developmentally regulated responses to lipopolysaccharide between birth and 5 years

Background

Human perinatal life is characterized by a period of extraordinary change during which newborns encounter abundant environmental stimuli and exposure to potential pathogens. To meet such challenges, the neonatal immune system is equipped with unique functional characteristics that adapt to changing conditions as development progresses across the early years of life, but the molecular characteristics of such adaptations remain poorly understood. The application of single cell genomics to birth cohorts provides an opportunity to investigate changes in gene expression programs elicited downstream of innate immune activation across early life at unprecedented resolution.

Methods

In this study, we performed single cell RNA-sequencing of mononuclear cells collected from matched birth cord blood and 5-year peripheral blood samples following stimulation (18hrs) with two well-characterized innate stimuli; lipopolysaccharide (LPS) and Polyinosinic:polycytidylic acid (Poly(I:C)).

Results

We found that the transcriptional response to LPS was constrained at birth and predominantly partitioned into classical proinflammatory gene upregulation primarily by monocytes and Interferon (IFN)-signaling gene upregulation by lymphocytes. Moreover, these responses featured substantial cell-to-cell communication which appeared markedly strengthened between birth and 5 years. In contrast, stimulation with Poly(I:C) induced a robust IFN-signalling response across all cell types identified at birth and 5 years. Analysis of gene regulatory networks revealed IRF1 and STAT1 were key drivers of the LPS-induced IFN-signaling response in lymphocytes with a potential developmental role for IRF7 regulation.

Conclusion

Additionally, we observed distinct activation trajectory endpoints for monocytes derived from LPS-treated cord and 5-year blood, which was not apparent among Poly(I:C)-induced monocytes. Taken together, our findings provide new insight into the gene regulatory landscape of immune cell function between birth and 5 years and point to regulatory mechanisms relevant to future investigation of infection susceptibility in early life.

5-Methoxytryptophan ameliorates endotoxin-induced acute lung injury in vivo and in vitro by inhibiting NLRP3 inflammasome-mediated pyroptosis through the Nrf2/HO-1 signaling pathway

BACKGROUND AND AIM

Endotoxin-induced acute lung injury (ALI) is a complicated and fatal condition with no specific or efficient clinical treatments. 5-Methoxytryptophan (5-MTP), an endogenous metabolite of tryptophan, was revealed to block systemic inflammation. However, the specific mechanism by which 5-MTP affects ALI still needs to be clarified. The purpose of this study was to determine whether 5-MTP protected the lung by inhibiting NLRP3 inflammasome-mediated pyroptosis through the Nrf2/HO-1 signaling pathway.

METHODS AND RESULTS

We used lipopolysaccharide (LPS)-stimulated C57BL/6 J mice and MH-S alveolar macrophages to create models of ALI, and 5-MTP (100 mg/kg) administration attenuated pathological lung damage in LPS-exposed mice, which was associated with decreased inflammatory cytokines and oxidative stress levels, upregulated protein expression of Nrf2 and HO-1, and suppressed Caspase-1 activation and NLRP3-mediated pyroptosis protein levels. Moreover, Nrf2-deficient mice or MH-S cells were treated with 5-MTP to further confirm the protective effect of the Nrf2/HO-1 pathway on lung damage. We found that Nrf2 deficiency partially eliminated the beneficial effect of 5-MTP on reducing oxidative stress levels and inflammatory responses and abrogating the inhibition of NLRP3-mediated pyroptosis induced by LPS.

CONCLUSION

These findings suggested that 5-MTP could effectively ameliorate ALI by inhibiting NLRP3-mediated pyroptosis via the Nrf2/HO-1 signaling pathway.

USP10 regulates macrophage inflammation responses via stabilizing NEMO in LPS-induced sepsis

BACKGROUND

Sepsis is a systemic inflammatory response syndrome characterized by persistent inflammation and immunosuppression, leading to septic shock and multiple organ dysfunctions. Ubiquitin-specific peptidase 10 (USP10), a deubiquitinase enzyme, plays a vital role in cancer and arterial restenosis, but its involvement in sepsis is unknown.

OBJECTIVE

In this study, we investigated the significance of USP10 in lipopolysaccharide (LPS)-stimulated macrophages and its biological roles in LPS-induced sepsis.

METHODS

Lipopolysaccharides (LPS) were used to establish sepsis models in vivo and in vitro. We use western blot to identify USP10 expression in macrophages. Spautin-1 and USP10-siRNA were utilized for USP10 inhibition. ELISA assays were used to assess for TNF-α and IL-6 in vitro and in vivo. Nuclear and cytoplasmic protein extraction and Confocal microscopy were applied to verify the translocation of NF-κB. Mechanically, co-immunoprecipitation and rescue experiments were used to validate the regulation of USP10 and NEMO.

RESULTS

In macrophages, we found that LPS induced USP10 upregulation. The inhibition or knockdown of USP10 reduced the pro-inflammatory cytokines TNF-α and IL-6 and suppressed LPS-induced NF-κB activation by regulating the translocation of NF-κB. Furthermore, we found that NEMO, the regulatory subunit NF-κB essential modulator, was essential for the regulation of LPS-induced inflammation by USP10 in macrophages. NEMO protein evidently interacted with USP10, whereby USP10 inhibition accelerated the degradation of NEMO. Suppressing USP10 significantly attenuated inflammatory responses and improved the survival rate in LPS-induced sepsis mice.

CONCLUSIONS

Overall, USP10 was shown to regulate inflammatory responses by stabilizing the NEMO protein, which may be a potential therapeutic target for sepsis-induced lung injury.

TRIM29 hypermethylation drives esophageal cancer progression via suppression of ZNF750

Esophageal cancer (ESCA) is the seventh most frequent and deadly neoplasm. Due to the lack of early diagnosis and high invasion/metastasis, the prognosis of ESCA remains very poor. Herein, we identify skin-related signatures as the most deficient signatures in invasive ESCA, which are regulated by the transcription factor ZNF750. Of note, we find that TRIM29 level strongly correlated with the expression of many genes in the skin-related signatures, including ZNF750. TRIM29 is significantly down-regulated due to hypermethylation of its promoter in both ESCA and precancerous lesions compared to normal tissues. Low TRIM29 expression and high methylation levels of its promoter are associated with malignant progression and poor clinical outcomes in ESCA patients. Functionally, TRIM29 overexpression markedly hinders proliferation, migration, invasion, and epithelial-mesenchymal transition of esophageal cancer cells, whereas opposing results are observed when TRIM29 is silenced in vitro. In addition, TRIM29 inhibits metastasis in vivo. Mechanistically, TRIM29 downregulation suppresses the expression of the tumor suppressor ZNF750 by activating the STAT3 signaling pathway. Overall, our study demonstrates that TRIM29 expression and its promoter methylation status could be potential early diagnostic and prognostic markers. It highlights the role of the TRIM29-ZNF750 signaling axis in modulating tumorigenesis and metastasis of esophageal cancer.

Regulatory mechanisms of macrophage polarization in adipose tissue

In adipose tissue, macrophages are the most abundant immune cells with high heterogeneity and plasticity. Depending on environmental cues and molecular mediators, adipose tissue macrophages (ATMs) can be polarized into pro- or anti-inflammatory cells. In the state of obesity, ATMs switch from the M2 polarized state to the M1 state, which contributes to chronic inflammation, thereby promoting the pathogenic progression of obesity and other metabolic diseases. Recent studies show that multiple ATM subpopulations cluster separately from the M1 or M2 polarized state. Various factors are related to ATM polarization, including cytokines, hormones, metabolites and transcription factors. Here, we discuss our current understanding of the potential regulatory mechanisms underlying ATM polarization induced by autocrine and paracrine factors. A better understanding of how ATMs polarize may provide new therapeutic strategies for obesity-related diseases.

TRIM29 promotes podocyte pyroptosis in diabetic nephropathy through the NF-kB/NLRP3 inflammasome pathway

Diabetic nephropathy (DN) is one of the most common complications of diabetes. Gradual loss of podocytes is a sign of DN and pyroptosis mechanistically correlates with podocyte injury in DN; however, the mechanism(s) involved remain unknown. Here we reveal that TRIM29 is overexpressed in high glucose (HG)-treated murine podocytes cells and that TRIM29 silencing significantly inhibits podocyte damage due to HG treatment, as evidenced by lower desmin expression and greater nephrin expression. Additionally, flow cytometry analysis showed that TRIM29 silencing significantly inhibited HG treatment-induced pyroptosis, which was confirmed by immunoblotting for NLRP3, active Caspase-1, GSDMD-N, and phosphorylated NF-κB-p65. Conversely, overexpression of TRIM29 could trigger pyroptosis that was attenuated by NF-κB inhibition, indicating that TRIM29 promotes pyroptosis through the NF-κB pathway. Mechanistic studies revealed that TRIM29 interacts with IκBα to mediate its ubiquitination-dependent degradation, which in turn leads to NF-κB activation. Taken together, our data demonstrate that TRIM29 can promote podocyte pyroptosis by activating the NF-κB/NLRP3 pathway. Thus, TRIM29 represents a potentially novel therapeutic target that may also be clinically relevant in the management of DN.

A novel interleukin-2-based fusion molecule, HCW9302, differentially promotes regulatory T cell expansion to treat atherosclerosis in mice

Atherosclerosis is a chronic inflammatory disease caused by deposition of oxidative low-density lipoprotein (LDL) in the arterial intima which triggers the innate immune response through myeloid cells such as macrophages. Regulatory T cells (Tregs) play an important role in controlling the progression or regression of atherosclerosis by resolving macrophage-mediated inflammatory functions. Interleukin-2 (IL-2) signaling is essential for homeostasis of Tregs. Since recombinant IL-2 has an unfavorable pharmacokinetic profile limiting its therapeutic use, we constructed a fusion protein, designated HCW9302, containing two IL-2 domains linked by an extracellular tissue factor domain. We found that HCW9302 exhibited a longer serum half-life with an approximately 1000-fold higher affinity for the IL-2Rα than IL-2. HCW9302 could be administered to mice at a dosing range that expanded and activated Tregs but not CD4⁺ effector T cells. In an ApoE^-/- mouse model, HCW9302 treatment curtailed the progression of atherosclerosis through Treg activation and expansion, M2 macrophage polarization and myeloid-derived suppressor cell induction. HCW9302 treatment also lessened inflammatory responses in the aorta. Thus, HCW9302 is a potential therapeutic agent to expand and activate Tregs for treatment of inflammatory and autoimmune diseases.

Chronic exposure to low-level lipopolysaccharide dampens influenza-mediated inflammatory response via A20 and PPAR network

Influenza A virus (IAV) infection leads to severe inflammation, and while epithelial-driven inflammatory responses occur via activation of NF-κB, the factors that modulate inflammation, particularly the negative regulators are less well-defined. In this study we show that A20 is a crucial molecular switch that dampens IAV-induced inflammatory responses. Chronic exposure to low-dose LPS environment can restrict this excessive inflammation. The mechanisms that this environment provides to suppress inflammation remain elusive. Here, our evidences show that chronic exposure to low-dose LPS suppressed IAV infection or LPS stimulation-induced inflammation in vitro and in vivo. Chronic low-dose LPS environment increases A20 expression, which in turn positively regulates PPAR-α and -γ, thus dampens the NF-κB signaling pathway and NLRP3 inflammasome activation. Knockout of A20 abolished the inhibitory effect on inflammation. Thus, A20 and its induced PPAR-α and -γ play a key role in suppressing excessive inflammatory responses in the chronic low-dose LPS environment.

Duck TRIM29 negatively regulates type I IFN production by targeting MAVS

The innate immune response is a host defense mechanism that induces type I interferon and proinflammatory cytokines. Tripartite motif (TRIM) family proteins have recently emerged as pivotal regulators of type I interferon production in mammals. Here, we first identified duck TRIM29, which encodes 571 amino acids and shows high sequence homology with other bird TRIM29 proteins. DuTRIM29 inhibited IFN-β and IRF7 promoter activation in a dose-dependent manner and downregulated the mRNA expression of IFN-β, IRF7, Mx and IL-6 mediated by duRIG-I. Moreover, duTRIM29 interacted and colocalized with duMAVS in the cytoplasm. DuTRIM29 interacted with duMAVS via its C-terminal domains. In addition, duTRIM29 inhibited IFN-β and IRF7 promoter activation and significantly downregulated IFN-β and immune-related gene expression mediated by duMAVS in ducks. Furthermore, duTRIM29 induced K29-linked polyubiquitination and degradation of duMAVS to suppress the expression of IFN-β. Overall, our results demonstrate that duTRIM29 negatively regulates type I IFN production by targeting duMAVS in ducks. This study will contribute to a better understanding of the molecular mechanism regulating the innate immune response by TRIM proteins in ducks.

Increased IKKϵ protein stability ensures efficient type I interferon responses in conditions of TBK1 deficiency

TBK1 and IKKϵ are related, crucial kinases in antiviral immune signaling pathways downstream of cytosolic nucleic acid receptors such as cGAS and RIG-I-like receptors. Upon activation, they phosphorylate the transcription factors IRF3 and IRF7 and thereby initiate the expression of type I interferons and antiviral effectors. While point mutation-induced loss of TBK1 kinase activity results in clinical hyper-susceptibility to viral infections, a complete lack of TBK1 expression in humans is unexpectedly not associated with diminished antiviral responses. Here, we provide a mechanistic explanation for these so-far unexplained observations by showing that TBK1 controls the protein expression of its related kinase IKKϵ in human myeloid cells. Mechanistically, TBK1 constitutively diminishes the protein stability of IKKϵ independent of TBK1 kinase activity but dependent on its interaction with the scaffold protein TANK. In consequence, depletion of TBK1 protein but not mutation-induced kinase deficiency induces the upregulation of IKKϵ. Due to the functional redundancy of the kinases in cGAS-STING and RIG-I-like receptor signaling in human myeloid cells, enhanced IKKϵ expression can compensate for the loss of TBK1. We show that IKKϵ upregulation is crucial to ensure unmitigated type I interferon production in conditions of TBK1 deficiency: While the type I interferon response to Listeria monocytogenes infection is maintained upon TBK1 loss, it is strongly diminished in cells harboring a kinase-deficient TBK1 variant, in which IKKϵ is not upregulated. Many pathogens induce TBK1 degradation, suggesting that loss of TBK1-mediated destabilization of IKKϵ is a critical backup mechanism to prevent diminished interferon responses upon TBK1 depletion.

Approaches to Evaluating Necroptosis in Virus-Infected Cells

The immune system functions to protect the host from pathogens. To counter host defense mechanisms, pathogens have developed unique strategies to evade detection or restrict host immune responses. Programmed cell death is a major contributor to the multiple host responses that help to eliminate infected cells for obligate intracellular pathogens like viruses. Initiation of programmed cell death pathways during the early stages of viral infections is critical for organismal survival as it restricts the virus from replicating and serves to drive antiviral inflammation immune recruitment through the release of damage-associated molecular patterns (DAMPs) from the dying cell. Necroptosis has been implicated as a critical programmed cell death pathway in a diverse set of diseases and pathological conditions including acute viral infections. This cell death pathway occurs when certain host sensors are triggered leading to the downstream induction of mixed-lineage kinase domain-like protein (MLKL). MLKL induction leads to cytoplasmic membrane disruption and subsequent cellular destruction with the release of DAMPs. As the role of this cell death pathway in human disease becomes apparent, methods identifying necroptosis patterns and outcomes will need to be further developed. Here, we discuss advances in our understanding of how viruses counteract necroptosis, methods to quantify the pathway, its effects on viral pathogenesis, and its impact on cellular signaling.

Regulation of CD18 stability by SIGIRR-modulated ubiquitination: new insights into the relationship between innate immune response and acute lung injury

Inappropriate accumulation of alveolar macrophages (AMs) and subsequent excessive production of immune responses play critical roles in the pathogenesis of acute lung injury (ALI), but the core negative regulators governing innate signalling in AMs are ill defined. We have previously shown that single immunoglobin IL-1 receptor-related protein (SIGIRR), a negative regulator of IL-1 receptor and Toll-like receptor signalling, inhibits lipopolysaccharide (LPS)-induced inflammatory responses in AMs. To address the biological relevance of SIGIRR in vivo, we generated a murine ALI model via intratracheal instillation of LPS. Intriguingly, SIGIRR expression was observed to be decreased in resident and recruited macrophages during ALI. This decrease was associated with parallel induction in CD18 protein levels in LPS-challenged lung tissues. Through intranasal injection of SIGIRR lentiviral particles studies, we showed that the overexpression of SIGIRR attenuated recruitment of macrophages and neutrophils, decreased production of inflammatory cytokines and ameliorated pathological changes in lungs. Whilst exploring the basis for this phenotype, SIGIRR was found to be coexpressed with CD18 in AMs, and SIGIRR potentiated the instability of CD18 protein via enhancement of its ubiquitination and proteasome degradation. Conversely, by using CD18^-/- mice, we further observed that CD18 deletion completely abolished the therapeutic effects of overexpression of SIGIRR on LPS-induced ALI. Mover, overexpression of CD18 in AMs promoted adhesion to ECM components, enhanced TLR4-mediated inflammasome activation and thereby potentiated IL-1β production. These data collectively identify SIGIRR/CD18 as a key negative regulatory circuit maintaining innate immune homeostasis in AMs along the pathogenesis of ALI.

Whole-transcriptome analyses of sheep embryonic testicular cells infected with the bluetongue virus

Introduction

bluetongue virus (BTV) infection triggers dramatic and complex changes in the host's transcriptional profile to favor its own survival and reproduction. However, there is no whole-transcriptome study of susceptible animal cells with BTV infection, which impedes the in-depth and systematical understanding of the comprehensive characterization of BTV-host interactome, as well as BTV infection and pathogenic mechanisms.

Methods

to systematically understand these changes, we performed whole-transcriptome sequencing in BTV serotype 1 (BTV-1)-infected and mock-infected sheep embryonic testicular cells, and subsequently conducted bioinformatics differential analyses.

Results

there were 1504 differentially expressed mRNAs, 78 differentially expressed microRNAs, 872 differentially expressed long non-coding RNAs, and 59 differentially expressed circular RNAs identified in total. Annotation from the Gene Ontology, enrichment from the Kyoto Encyclopedia of Genes and Genomes, and construction of competing endogenous RNA networks revealed differentially expressed RNAs primarily related to virus-sensing and signaling transduction pathways, antiviral and immune responses, inflammation, and development and metabolism related pathways. Furthermore, a protein-protein interaction network analysis found that BTV may contribute to abnormal spermatogenesis by reducing steroid biosynthesis. Finally, real-time quantitative PCR and western blotting results showed that the expression trends of differentially expressed RNAs were consistent with the whole-transcriptome sequencing data.

Discussion

this study provides more insights of comprehensive characterization of BTV-host interactome, and BTV infection and pathogenic mechanisms.

E3 Ubiquitin Ligases: The Operators of the Ubiquitin Code That Regulates the RLR and cGAS-STING Pathways

The outbreaks caused by RNA and DNA viruses, such as SARS-CoV-2 and monkeypox, pose serious threats to human health. The RLR and cGAS-STING pathways contain major cytoplasmic sensors and signaling transduction axes for host innate antiviral immunity. In physiological and virus-induced pathological states, the activation and inactivation of these signal axes are tightly controlled, especially post-translational modifications (PTMs). E3 ubiquitin ligases (E3s) are the direct manipulator of ubiquitin codons and determine the type and modification type of substrate proteins. Therefore, members of the E3s family are involved in balancing the host's innate antiviral immune responses, and their functions have been extensively studied over recent decades. In this study, we overviewed the mechanisms of different members of three E3s families that mediate the RLR and cGAS-STING axes and analyzed them as potential molecular targets for the prevention and treatment of virus-related diseases.

Macrophage autophagy in macrophage polarization, chronic inflammation and organ fibrosis

As the essential regulators of organ fibrosis, macrophages undergo marked phenotypic and functional changes after organ injury. These changes in macrophage phenotype and function can result in maladaptive repair, causing chronic inflammation and the development of pathological fibrosis. Autophagy, a highly conserved lysosomal degradation pathway, is one of the major players to maintain the homeostasis of macrophages through clearing protein aggregates, damaged organelles, and invading pathogens. Emerging evidence has shown that macrophage autophagy plays an essential role in macrophage polarization, chronic inflammation, and organ fibrosis. Because of the high heterogeneity of macrophages in different organs, different macrophage types may play different roles in organ fibrosis. Here, we review the current understanding of the function of macrophage autophagy in macrophage polarization, chronic inflammation, and organ fibrosis in different organs, highlight the potential role of macrophage autophagy in the treatment of fibrosis. Finally, the important unresolved issues in this field are briefly discussed. A better understanding of the mechanisms that macrophage autophagy in macrophage polarization, chronic inflammation, and organ fibrosis may contribute to developing novel therapies for chronic inflammatory diseases and organ fibrosis.

Adipose tissue macrophages in remote modulation of hepatic glucose production

Hepatic glucose production (HGP) is fine-regulated via glycogenolysis or gluconeogenesis to maintain physiological concentration of blood glucose during fasting-feeding cycle. Aberrant HGP leads to hyperglycemia in obesity-associated diabetes. Adipose tissue cooperates with the liver to regulate glycolipid metabolism. During these processes, adipose tissue macrophages (ATMs) change their profiles with various physio-pathological settings, producing diverse effects on HGP. Here, we briefly review the distinct phenotypes of ATMs under different nutrition states including feeding, fasting or overnutrition, and detail their effects on HGP. We discuss several pathways by which ATMs regulate hepatic gluconeogenesis or glycogenolysis, leading to favorable or unfavorable metabolic consequences. Furthermore, we summarize emerging therapeutic targets to correct metabolic disorders in morbid obesity or diabetes based on ATM-HGP axis. This review puts forward the importance and flexibility of ATMs in regulating HGP, proposing ATM-based HGP modulation as a potential therapeutic approach for obesity-associated metabolic dysfunction.

BAG6 negatively regulates the RLR signaling pathway by targeting VISA/MAVS

The virus-induced signaling adaptor protein VISA (also known as MAVS, ISP-1, Cardif) is a critical adaptor protein in the innate immune response to RNA virus infection. Upon viral infection, VISA self-aggregates to form a sizeable prion-like complex and recruits downstream signal components for signal transduction. Here, we discover that BAG6 (BCL2-associated athanogene 6, formerly BAT3 or Scythe) is an essential negative regulator in the RIG-I-like receptor signaling pathway. BAG6 inhibits the aggregation of VISA by promoting the K48-linked ubiquitination and specifically attenuates the recruitment of TRAF2 by VISA to inhibit RLR signaling. The aggregation of VISA and the interaction of VISA and TRAF2 are enhanced in BAG6-deficient cell lines after viral infection, resulting in the enhanced transcription level of downstream antiviral genes. Our research shows that BAG6 is a critical regulating factor in RIG-I/VISA-mediated innate immune response by targeting VISA.

TRIM18 is a critical regulator of viral myocarditis and organ inflammation

BACKGROUND

Infections by viruses including severe acute respiratory syndrome coronavirus 2 could cause organ inflammations such as myocarditis, pneumonia and encephalitis. Innate immunity to viral nucleic acids mediates antiviral immunity as well as inflammatory organ injury. However, the innate immune mechanisms that control viral induced organ inflammations are unclear.

METHODS

To understand the role of the E3 ligase TRIM18 in controlling viral myocarditis and organ inflammation, wild-type and Trim18 knockout mice were infected with coxsackievirus B3 for inducing viral myocarditis, influenza A virus PR8 strain and human adenovirus for inducing viral pneumonia, and herpes simplex virus type I for inducing herpes simplex encephalitis. Mice survivals were monitored, and heart, lung and brain were harvested for histology and immunohistochemistry analysis. Real-time PCR, co-immunoprecipitation, immunoblot, enzyme-linked immunosorbent assay, luciferase assay, flow cytometry, over-expression and knockdown techniques were used to understand the molecular mechanisms of TRIM18 in regulating type I interferon (IFN) production after virus infection in this study.

RESULTS

We find that knockdown or deletion of TRIM18 in human or mouse macrophages enhances production of type I IFN in response to double strand (ds) RNA and dsDNA or RNA and DNA virus infection. Importantly, deletion of TRIM18 protects mice from viral myocarditis, viral pneumonia, and herpes simplex encephalitis due to enhanced type I IFN production in vivo. Mechanistically, we show that TRIM18 recruits protein phosphatase 1A (PPM1A) to dephosphorylate TANK binding kinase 1 (TBK1), which inactivates TBK1 to block TBK1 from interacting with its upstream adaptors, mitochondrial antiviral signaling (MAVS) and stimulator of interferon genes (STING), thereby dampening antiviral signaling during viral infections. Moreover, TRIM18 stabilizes PPM1A by inducing K63-linked ubiquitination of PPM1A.

CONCLUSIONS

Our results indicate that TRIM18 serves as a negative regulator of viral myocarditis, lung inflammation and brain damage by downregulating innate immune activation induced by both RNA and DNA viruses. Our data reveal that TRIM18 is a critical regulator of innate immunity in viral induced diseases, thereby identifying a potential therapeutic target for treatment.

RNA-seq Based Transcriptome Analysis Reveals The Cross-Talk of Macrophage and Adipocyte of Chicken Subcutaneous Adipose Tissue during The Embryonic and Post-Hatch Period

With high fecundity and short production cycle, poultry is one of the important sources of meat. During the embryonic and post-hatch period, the higher death rate caused huge economic losses in poultry production. Our previous study showed that chick subcutaneous adipose tissue is an important energy supply tissue besides yolk. Therefore, the metabolic mechanism of subcutaneous adipose tissue in chicks could provide a new perspective of brooding. The objectives of the current study were to evaluate the differences between chick subcutaneous adipose tissue and abdominal adipose tissue before and after hatching and reveal the cross-talk of different cells within the chick subcutaneous adipose tissue. The results of RNA-seq and weighted gene co-expression network analysis (WGCNA) of chick subcutaneous and abdominal adipose tissues showed that the function of chick subcutaneous tissue was related to immunoreaction, and macrophage could be the major immune infiltration cell type in chicken subcutaneous adipose tissue, which were also verified by qPCR, HE stain, and IHC. The results of free fatty acids (FFAs)-induced the cross-talk between macrophages and adipocytes showed that FFAs-Ccl2 (chicken CCL26) axis could have an important role in lipid transportation in adipose tissue. The results of Oil Red O and Nile red stain demonstrated that macrophages have the ability to absorb FFAs quickly. Interestingly, according to the genomic organization of CCL family with representative vertebrate species, we found that chicken CCL26 could be the major chemokine in chicken adipocyte as the status of CCL2 in mammal adipocyte. In conclusion, we demonstrate that FFA-induced Ccl2 (chicken CCL26) secretion is crucial in determining fat depot-selective adipose tissue macrophage (ATM) infiltration, which could be an important medium of lipid transportation in chicken subcutaneous adipose tissue. These findings may have multiple important implications for understanding macrophage biology with chick subcutaneous adipose tissue and provide theoretical basis for lipid metabolism in poultry brooding.

Monocyte-derived alveolar macrophages autonomously determine severe outcome of respiratory viral infection

Various lung insults can result in replacement of resident alveolar macrophages (AM) by bone marrow monocyte-derived (BMo)-AM. However, the dynamics of this process and its long-term consequences for respiratory viral infections remain unclear. Using several mouse models and a marker to unambiguously track fetal monocyte-derived (FeMo)-AM and BMo-AM, we established the kinetics and extent of replenishment and their function to recurrent influenza A virus (IAV) infection. A massive loss of FeMo-AM resulted in rapid replenishment by self-renewal of survivors, followed by the generation of BMo-AM. BMo-AM progressively outcompeted FeMo-AM over several months, and this was due to their increased glycolytic and proliferative capacity. The presence of both naïve and experienced BMo-AM conferred severe pathology to IAV infection, which was associated with a proinflammatory phenotype. Furthermore, upon aging of naïve mice, FeMo-AM were gradually replaced by BMo-AM, which contributed to IAV disease severity in a cell-autonomous manner. Together, our results suggest that the origin rather than training of AM determines long-term function to respiratory viral infection and provide an explanation for the increased severity of infection seen in the elderly.

The Roles of Adipose Tissue Macrophages in Human Disease

Macrophages are a population of immune cells functioning in antigen presentation and inflammatory response. Research has demonstrated that macrophages belong to a cell lineage with strong plasticity and heterogeneity and can be polarized into different phenotypes under different microenvironments or stimuli. Many macrophages can be recruited by various cytokines secreted by adipose tissue. The recruited macrophages further secrete various inflammatory factors to act on adipocytes, and the interaction between the two leads to chronic inflammation. Previous studies have indicated that adipose tissue macrophages (ATMs) are closely related to metabolic diseases like obesity and diabetes. Here, we will not only conclude the current progress of factors affecting the polarization of adipose tissue macrophages but also elucidate the relationship between ATMs and human diseases. Furthermore, we will highlight its potential in preventing and treating metabolic diseases as immunotherapy targets.

Reovirus Activated Cell Death Pathways

Mammalian orthoreoviruses (ReoV) are non-enveloped viruses with segmented double-stranded RNA genomes. In humans, ReoV are generally considered non-pathogenic, although members of this family have been proven to cause mild gastroenteritis in young children and may contribute to the development of inflammatory conditions, including Celiac disease. Because of its low pathogenic potential and its ability to efficiently infect and kill transformed cells, the ReoV strain Type 3 Dearing (T3D) is clinical trials as an oncolytic agent. ReoV manifests its oncolytic effects in large part by infecting tumor cells and activating programmed cell death pathways (PCDs). It was previously believed that apoptosis was the dominant PCD pathway triggered by ReoV infection. However, new studies suggest that ReoV also activates other PCD pathways, such as autophagy, pyroptosis, and necroptosis. Necroptosis is a caspase-independent form of PCD reliant on receptor-interacting serine/threonine-protein kinase 3 (RIPK3) and its substrate, the pseudokinase mixed-lineage kinase domain-like protein (MLKL). As necroptosis is highly inflammatory, ReoV-induced necroptosis may contribute to the oncolytic potential of this virus, not only by promoting necrotic lysis of the infected cell, but also by inflaming the surrounding tumor microenvironment and provoking beneficial anti-tumor immune responses. In this review, we summarize our current understanding of the ReoV replication cycle, the known and potential mechanisms by which ReoV induces PCD, and discuss the consequences of non-apoptotic cell death—particularly necroptosis—to ReoV pathogenesis and oncolysis.

The Adipose Tissue Macrophages Central to Adaptive Thermoregulation

White fat stores excess energy, and thus its excessive expansion causes obesity. However, brown and beige fat, known as adaptive thermogenic fat, dissipates energy in the form of heat and offers a therapeutic potential to counteract obesity and metabolic disorders. The fat type-specific biological function is directed by its unique tissue microenvironment composed of immune cells, endothelial cells, pericytes and neuronal cells. Macrophages are major immune cells resident in adipose tissues and gained particular attention due to their accumulation in obesity as the primary source of inflammation. However, recent studies identified macrophages’ unique role and regulation in thermogenic adipose tissues to regulate energy expenditure and systemic energy homeostasis. This review presents the current understanding of macrophages in thermogenic fat niches with an emphasis on discrete macrophage subpopulations central to adaptive thermoregulation.

Tripartite motif family proteins in inflammatory bowel disease: Mechanisms and potential for interventions

Inflammatory bowel disease (IBD) is a chronic recurrent gastrointestinal inflammatory disease that poses a heavy burden to the global healthcare system. However, the current paucity of mechanistic understanding of IBD pathogenesis hampers the development of aetiology‐directed therapies. Novel therapeutic options based on IBD pathogenesis are urgently needed for attaining better long‐term prognosis for IBD patients. The tripartite motif (TRIM) family is a large protein family including more than 70 structurally conservative members, typically characterized by their RBCC structure, which primarily function as E3 ubiquitin ligases in post‐translational modification. They have emerged as regulators of a broad range of cellular mechanisms, including proliferation, differentiation, transcription and immune regulation. TRIM family proteins are involved in multiple diseases, such as viral infection, cancer and autoimmune disorders, including inflammatory bowel disease. This review provides a comprehensive perspective on TRIM proteins' involvement in the pathophysiology and progression of IBD, in particular, on intestinal mucosal barriers, gene susceptibility and opportunistic infections, thus providing novel therapeutic targets for this complicated disease. However, the exact mechanisms of TRIM proteins in IBD pathogenesis and IBD‐related carcinogenesis are still unknown, and more studies are warranted to explore potential therapeutic targets of TRIM proteins in IBD.

KAP1 Positively Modulates Influenza A Virus Replication by Interacting with PB2 and NS1 Proteins in Human Lung Epithelial Cells

Influenza virus only encodes a dozen of viral proteins, which need to use host machinery to complete the viral life cycle. Previously, KAP1 was identified as one host protein that potentially interacts with influenza viral proteins in HEK 293 cells. However, the role of KAP1 in influenza virus replication in human lung alveolar epithelial cells and the underlying mechanism remains unclear. In this study, we first generated KAP1 KO A549 cells by CRISPR/Cas9 gene editing. KAP1 deletion had no significant effect on the cell viability and lack of KAP1 expression significantly reduced the influenza A virus replication. Moreover, we demonstrated that KAP1 is involved in the influenza virus entry, transcription/replication of viral genome, and viral protein synthesis in human lung epithelial cells and confirmed that KAP1 interacted with PB2 and NS1 viral proteins during the virus infection. Further study showed that KAP1 inhibited the production of type I IFN and overexpression of KAP1 significantly reduced the IFN-β production. In addition, influenza virus infection induces the deSUMOylation and enhanced phosphorylation of KAP1. Our results suggested that KAP1 is required for the replication of influenza A virus and mediates the replication of influenza A virus by facilitating viral infectivity and synthesis of viral proteins, enhancing viral polymerase activity, and inhibiting the type I IFN production.

Genetically programmed alternative splicing of NEMO mediates an autoinflammatory disease phenotype

Host defense and inflammation are regulated by the NF-κB essential modulator (NEMO), a scaffolding protein with a broad immune cell and tissue expression profile. Hypomorphic mutations in inhibitor of NF-κB kinase regulatory subunit gamma (IKBKG) encoding NEMO typically present with immunodeficiency. Here, we characterized a pediatric autoinflammatory syndrome in 3 unrelated male patients with distinct X-linked IKBKG germline mutations that led to overexpression of a NEMO protein isoform lacking the domain encoded by exon 5 (NEMO-Δex5). This isoform failed to associate with TANK binding kinase 1 (TBK1), and dermal fibroblasts from affected patients activated NF-κB in response to TNF but not TLR3 or RIG-I–like receptor (RLR) stimulation when isoform levels were high. By contrast, T cells, monocytes, and macrophages that expressed NEMO-Δex5 exhibited increased NF-κB activation and IFN production, and blood cells from these patients expressed a strong IFN and NF-κB transcriptional signature. Immune cells and TNF-stimulated dermal fibroblasts upregulated the inducible IKK protein (IKKi) that was stabilized by NEMO-Δex5, promoting type I IFN induction and antiviral responses. These data revealed how IKBKG mutations that lead to alternative splicing of skipping exon 5 cause a clinical phenotype we have named NEMO deleted exon 5 autoinflammatory syndrome (NDAS), distinct from the immune deficiency syndrome resulting from loss-of-function IKBKG mutations.

When cyclin-dependent kinases meet viral infections, including SARS-CoV-2

Cyclin‐dependent kinases (CDKs) are protein kinases that play a key role in cell division and transcriptional regulation. Recent studies have demonstrated the critical roles of CDKs in various viral infections. However, the molecular processes underpinning CDKs' roles in viral infection and host antiviral defense are unknown. This minireview briefly overviews CDKs' functions and highlights the most recent discoveries of CDKs' emerging roles during viral infections, thereby providing a scientific and theoretical foundation for antiviral regulation and shedding light on developing novel drug targets and therapeutic strategies against viral infection.