Expanding TRAF function: TRAF3 as a tri-faced immune regulator. Nat Rev Immunol. 2011;11:457-468. [PMID: 21660053 DOI: 10.1038/nri2998]

Inhibiting NF-κB inducing kinase improved the motor performance of ALS animal model

BACKGROUND

Amyotrophic lateral sclerosis (ALS) is a typical neurodegenerative disorder typically characterized by inflammation activation. However, the relationship between non-canonical NF-κB (ncNF-κB) pathway activation and ALS progression is not clear.

METHODS

We tested the ncNF-κB pathway in the ALS animal model including hSOD1-G93A transgenic mice and TBK1 deletion mice.We treated age-matched SOD1-G93A mice with B022 (a NIK inhibitor) to investigate the role of NIK in the ALS animal model. We also established a new mice model by crossing SOD1-G93A mice with NIK+/- mice to further evaluate the interrelationship between the NIK and the disease progression in ALS animal model.

RESULTS

In this study, we found the ncNF-κB pathway was activated in SOD1-G93A animal model and TBK1 deletion model. Inhibition of NIK activity by small molecule B022 significantly improved the motor performance of the ALS animal model. However, NIK deletion enhanced the mutant SOD1 toxicity by inflammatory infiltration.

CONCLUSION

TBK1 deletion and mutant SOD1 shared the common pathological feature possibly via effects on NIK activation and inhibitor of NIK could be a novel strategy for treating ALS.

Downregulation of miR-1388 Regulates the Expression of Antiviral Genes via Tumor Necrosis Factor Receptor (TNFR)-Associated Factor 3 Targeting Following poly(I:C) Stimulation in Silver Carp (Hypophthalmichthys molitrix)

MicroRNAs (miRNAs) are highly conserved endogenous single-stranded non-coding RNA molecules that play a crucial role in regulating gene expression to maintain normal physiological functions in fish. Nevertheless, the specific physiological role of miRNAs in lower vertebrates, particularly in comparison to mammals, remains elusive. Additionally, the mechanisms underlying the control of antiviral responses triggered by viral stimulation in fish are still not fully understood. In this study, we investigated the regulatory impact of miR-1388 on the signaling pathway mediated by IFN regulatory factor 3 (IRF3). Our findings revealed that following stimulation with the viral analog poly(I:C), the expression of miR-1388 was significantly upregulated in primary immune tissues and macrophages. Through a dual luciferase reporter assay, we corroborated a direct targeting relationship between miR-1388 and tumor necrosis factor receptor (TNFR)-associated factor 3 (TRAF3). Furthermore, our study demonstrated a distinct negative post-transcriptional correlation between miR-1388 and TRAF3. We observed a significant negative post-transcriptional regulatory association between miR-1388 and the levels of antiviral genes following poly(I:C) stimulation. Utilizing reporter plasmids, we elucidated the role of miR-1388 in the antiviral signaling pathway activated by TRAF3. By intervening with siRNA-TRAF3, we validated that miR-1388 regulates the expression of antiviral genes and the production of type I interferons (IFN-Is) through its interaction with TRAF3. Collectively, our experiments highlight the regulatory influence of miR-1388 on the IRF3-mediated signaling pathway by targeting TRAF3 post poly(I:C) stimulation. These findings provide compelling evidence for enhancing our understanding of the mechanisms through which fish miRNAs participate in immune responses.

The TRAF3-DYRK1A-RAD54L2 complex maintains ACE2 expression to promote SARS-CoV-2 infection

Angiotensin converting enzyme 2 (ACE2), the host receptor for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, is differentially expressed in a wide variety of tissues and cell types. The expression of ACE2 is under tight regulation, but the mechanisms regulating ACE2 expression have not yet been well defined. Through a genome-wide CRISPR knockout screen, we discovered that host factors TRAF3, DYRK1A, and RAD54L2 (TDR) form a complex to regulate the expression of ACE2. Knockout of TRAF3, DYRK1A, or RAD54L2 reduces the mRNA levels of ACE2 and inhibits the cellular entry of SARS-CoV-2. On the other hand, SARS-CoV-2 continuously evolves by genetic mutations for the adaption to the host. We have identified mutations in spike (S) (P1079T) and nucleocapsid (N) (S194L) that enhance the replication of SARS-CoV-2 in cells that express ACE2 at a low level. Our results have revealed the mechanisms for the transcriptional regulation of ACE2 and the adaption of SARS-CoV-2.

IMPORTANCE

The expression of ACE2 is essential for the entry of SARS-CoV-2 into host cells. We identify a new complex-the TDR complex-that acts to maintain the abundance of ACE2 in host cells. The identification and characterization of the TDR complex provide new targets for the development of therapeutics against SARS-CoV-2 infection. By analysis of SARS-CoV-2 virus replicating in cells expressing low levels of ACE2, we identified mutations in spike (P1079T) and nucleocapsid (S194L) that overcome the restriction of limited ACE2. Functional analysis of these key amino acids in S and N extends our knowledge of the impact of SARS-CoV-2 variants on virus infection and transmission.

TRAF1 from a Structural Perspective

Tumor necrosis factor receptor-associated factor (TRAF) proteins play pivotal roles in a multitude of cellular signaling pathways, encompassing immune response, cell fate determination, development, and thrombosis. Their involvement in these processes hinges largely on their ability to interact directly with diverse receptors via the TRAF domain. Given the limited binding interface, understanding how specific TRAF domains engage with various receptors and how structurally similar binding interfaces of TRAF family members adapt their distinct binding partners has been the subject of extensive structural investigations over several decades. This review presents an in-depth exploration of the current insights into the structural and molecular diversity exhibited by the TRAF domain and TRAF-binding motifs across a range of receptors, with a specific focus on TRAF1.

Effects of Long-Term Cryopreservation on the Transcriptomes of Giant Grouper Sperm

The giant grouper fish (Epinephelus lanceolatus), one of the largest and rarest groupers, is a fast-growing economic fish. Grouper sperm is often used for cross-breeding with other fish and therefore sperm cryopreservation is important. However, freezing damage cannot be avoided. Herein, we performed a transcriptome analysis to compare fresh and frozen sperm of the giant grouper with frozen storage times of 0, 23, 49, and 61 months. In total, 1911 differentially expressed genes (DEGs), including 91 in El-0-vs-El-23 (40 upregulated and 51 downregulated), 251 in El-0-vs-El-49 (152 upregulated and 69 downregulated), and 1569 in El-0-vs-El-61 (984 upregulated and 585 downregulated), were obtained in the giant grouper sperm. DEGs were significantly increased at 61 months of cryopreservation (p < 0.05). GO and KEGG enrichment analyses of the DEGs revealed significant enrichment in the pilus assembly, metabolic process, MAPK signaling pathway, apoptosis, and P53 signaling pathway. Time-series expression profiling of the DEGs showed that consistently upregulated modules were also significantly enriched in signaling pathways associated with apoptosis. Four genes, scarb1, odf3, exoc8, and atp5f1d, were associated with mitochondria and flagella in a weighted correlation network analysis. These genes may play an important role in the response to sperm freezing. The experimental results show that long-term cryopreservation results in freezing damage to the giant grouper sperm. This study provides rich data for studies of the mechanism underlying frozen fish sperm damage as well as a technical reference and evaluation index for the long-term cryopreservation of fish sperm.

The Effect of Enteric-Derived Lipopolysaccharides on Obesity

Endotoxin is a general term for toxic substances in Gram-negative bacteria, whose damaging effects are mainly derived from the lipopolysaccharides (LPS) in the cell walls of Gram-negative bacteria, and is a strong pyrogen. Obesity is a chronic, low-grade inflammatory condition, and LPS are thought to trigger and exacerbate it. The gut flora is the largest source of LPS in the body, and it is increasingly believed that altered intestinal microorganisms can play an essential role in the pathology of different diseases. Today, the complex axis linking gut flora to inflammatory states and adiposity has not been well elucidated. This review summarises the evidence for an interconnection between LPS, obesity, and gut flora, further expanding our understanding of LPS as a mediator of low-grade inflammatory disease and contributing to lessening the effects of obesity and related metabolic disorders. As well as providing targets associated with LPS, obesity, and gut flora, it is hoped that interventions that combine targets with gut flora address the individual differences in gut flora treatment.

ALKBH5-mediated m6A demethylation of pri-miR-199a-5p exacerbates myocardial ischemia/reperfusion injury by regulating TRAF3-mediated pyroptosis

Myocardial ischemia‒reperfusion injury (MI/RI) is closely related to pyroptosis. alkB homolog 5 (ALKBH5) is abnormally expressed in the MI/RI models. However, the detailed molecular mechanism of ALKBH5 in MI/RI has not been elucidated. In this study, rats and H9C2 cells served as experimental subjects and received MI/R induction and H/R induction, respectively. The abundance of the targeted molecules was evaluated using RT-qPCR, Western blotting, immunohistochemistry, immunofluorescence, and enzyme-linked immunosorbent assay. The heart functions of the rats were evaluated using echocardiography, and heart injury was evaluated. Cell viability and pyroptosis were determined using cell counting Kit-8 and flow cytometry, respectively. Total m6A modification was measured using a commercial kit, and pri-miR-199a-5p m6A modification was detected by Me-RNA immunoprecipitation (RIP) assay. The interactions among the molecules were validated using RIP and luciferase experiments. ALKBH5 was abnormally highly expressed in H/R-induced H9C2 cells and MI/RI rats. ALKBH5 silencing improved injury and inhibited pyroptosis. ALKBH5 reduced pri-miR-199a-5p m6A methylation to block miR-199a-5p maturation and inhibit its expression. TNF receptor-associated Factor 3 (TRAF3) is a downstream gene of miR-199a-5p. Furthermore, in H/R-induced H9C2 cells, the miR-199a-5p inhibitor-mediated promotion of pyroptosis was reversed by ALKBH5 silencing, and the TRAF3 overexpression-mediated promotion of pyroptosis was offset by miR-199a-5p upregulation. ALKBH5 silencing inhibited pri-miR-199a-5p expression and enhanced pri-miR-199a-5p m6A modification to promote miR-199a-5p maturation and enhance its expression, thereby suppressing pyroptosis to alleviate MI/RI through decreasing TRAF3 expression.

Mechanism study of ubiquitination in T cell development and autoimmune disease

T cells play critical role in multiple immune processes including antigen response, tumor immunity, inflammation, self-tolerance maintenance and autoimmune diseases et. Fetal liver or bone marrow-derived thymus-seeding progenitors (TSPs) settle in thymus and undergo T cell-lineage commitment, proliferation, T cell receptor (TCR) rearrangement, and thymic selections driven by microenvironment composed of thymic epithelial cells (TEC), dendritic cells (DC), macrophage and B cells, thus generating T cells with diverse TCR repertoire immunocompetent but not self-reactive. Additionally, some self-reactive thymocytes give rise to Treg with the help of TEC and DC, serving for immune tolerance. The sequential proliferation, cell fate decision, and selection during T cell development and self-tolerance establishment are tightly regulated to ensure the proper immune response without autoimmune reaction. There are remarkable progresses in understanding of the regulatory mechanisms regarding ubiquitination in T cell development and the establishment of self-tolerance in the past few years, which holds great potential for further therapeutic interventions in immune-related diseases.

NLRP12 Senses the SARS-CoV-2 Membrane Protein and Promotes an Inflammatory Response

COVID-19 is an acute respiratory disorder that is caused by SARS-CoV-2, in which excessive systemic inflammation is associated with adverse patient clinical outcomes. Here, we observed elevated expression levels of NLRP12 (nucleotide-binding leucine-rich repeat-containing receptor 12) in human peripheral monocytes and lung tissue during infection with SARS-CoV-2. Co-immunoprecipitation analysis revealed that NLRP12 directly interacted with the M protein through its leucine-rich repeat domain. Moreover, in vitro studies demonstrated that NLRP12 interacted with TRAF3 and promoted its ubiquitination and degradation, which counteracted the inhibitory effect of TRAF3 on the NF-κB/MAPK signaling pathway and promoted the production of inflammatory cytokines. Furthermore, an in vivo study revealed that NLRP12 knockout mice displayed attenuated tissue injury and ameliorated inflammatory responses in the lungs when infected with a SARS-CoV-2 M protein-reconstituted pseudovirus and mouse coronavirus. Taken together, these findings suggest that NLRP12 mediates the inflammatory responses during coronavirus infection.

Exploring type I interferon pathway: virulent vs. attenuated strain of African swine fever virus revealing a novel function carried by MGF505-4R

African swine fever virus represents a significant reemerging threat to livestock populations, as its incidence and geographic distribution have surged over the past decade in Europe, Asia, and Caribbean, resulting in substantial socio-economic burdens and adverse effects on animal health and welfare. In a previous report, we described the protective properties of our newly thermo-attenuated strain (ASFV-989) in pigs against an experimental infection of its parental Georgia 2007/1 virulent strain. In this new study, our objective was to characterize the molecular mechanisms underlying the attenuation of ASFV-989. We first compared the activation of type I interferon pathway in response to ASFV-989 and Georgia 2007/1 infections, employing both in vivo and in vitro models. Expression of IFN-α was significantly increased in porcine alveolar macrophages infected with ASFV-989 while pigs infected with Georgia 2007/1 showed higher IFN-α than those infected by ASFV-989. We also used a medium-throughput transcriptomic approach to study the expression of viral genes by both strains, and identified several patterns of gene expression. Subsequently, we investigated whether proteins encoded by the eight genes deleted in ASFV-989 contribute to the modulation of the type I interferon signaling pathway. Using different strategies, we showed that MGF505-4R interfered with the induction of IFN-α/β pathway, likely through interaction with TRAF3. Altogether, our data reveal key differences between ASFV-989 and Georgia 2007/1 in their ability to control IFN-α/β signaling and provide molecular mechanisms underlying the role of MGF505-4R as a virulence factor.

Alternative splicing of pre-mRNA modulates the immune response in Holstein cattle naturally infected with Mycobacterium avium subsp. paratuberculosis

Little is known about the role of alternative splicing (AS) in regulating gene expression in Mycobacteria-infected individuals in distinct stages of infection. Pre-mRNA AS consists of the removal of introns and the assembly of exons contained in eukaryotic genes. AS events can influence transcript stability or structure with important physiological consequences. Using RNA-Seq data from peripheral blood (PB) and ileocecal valve (ICV) samples collected from Holstein cattle with focal and diffuse paratuberculosis (PTB)-associated histopathological lesions in gut tissues and without lesions (controls), we detected differential AS profiles between the infected and control groups. Four of the identified AS events were experimentally validated by reverse transcription-digital droplet PCR (RT-ddPCR). AS events in several genes correlated with changes in gene expression. In the ICV of animals with diffuse lesions, for instance, alternatively spliced genes correlated with changes in the expression of genes involved in endocytosis, antigen processing and presentation, complement activation, and several inflammatory and autoimmune diseases in humans. Taken together, our results identified common mechanisms of AS involvement in the pathogenesis of PTB and human diseases and shed light on novel diagnostic and therapeutic interventions to control these diseases.

USP13 Cooperates with MARCH8 to Inhibit Antiviral Signaling by Targeting MAVS for Autophagic Degradation in Teleost

Mitochondrial antiviral signaling protein (MAVS), as a central adapter protein in retinoic acid-inducible gene I-like receptor signaling, is indispensable for innate antiviral immunity. Yet, the molecular mechanisms modulating the stability of MAVS are not fully understood in low vertebrates. In this study, we report that the deubiquitinase ubiquitin-specific protease 13 (USP13) acts as a negative regulator of antiviral immunity by targeting MAVS for selective autophagic degradation in teleost fish. USP13 is induced by RNA virus or polyinosinic:polycytidylic acid stimulation and acts as a negative regulator to potentiate viral replication in fish cells. Mechanistically, USP13 functions as a scaffold to enhance the interaction between MAVS and the E3 ubiquitin ligase MARCH8, thus promoting MARCH8 to catalyze MAVS through K27-linked polyubiquitination for selective autophagic degradation. Taken together, to our knowledge, our study demonstrates a novel mechanism by which viruses evade host antiviral immunity via USP13 in fish and provides a new idea for mammalian innate antiviral immunity.

Cytokine and chemokine profiles in ulcerative colitis relapse after coronavirus disease 2019 vaccination

Coronavirus disease 2019 (COVID-19) vaccines are highly effective; however, vaccine-related adverse events, including autoimmunity, have been reported. Case reports describing relapse or new-onset of ulcerative colitis (UC) after COVID-19 mRNA vaccination are available. However, the molecular mechanisms underlying the development of colonic inflammation associated with COVID-19 mRNA vaccination are poorly understood. Furthermore, it is unclear whether the relapse of UC after COVID-19 vaccination is driven by unique cytokine responses that differ from those of UC not associated with vaccination. mRNAs derived from COVID-19 vaccines are potent inducers of type I IFN response. We encountered three cases of UC relapse after COVID-19 vaccination. mRNA expressions of IFN-α, IFN-β, IL-1β, and IL-12/23p40 showed higher tendency in the colonic mucosa of patients with UC associated with vaccination compared with those not associated with vaccination. In contrast, the expressions of C-X-C motif chemokine ligand 9 (CXCL9) and CXCL10 were comparable. Immunofluorescence analyses also showed higher expression of IFN-α in the colonic mucosa of patients with UC associated with COVID-19 vaccination than in those not associated with vaccination. Taken together, these data suggest that the colonic mucosa of patients with UC who relapsed after COVID-19 vaccination was characterized by enhanced type I IFN responses.

EFHD2 cooperates with E3 ubiquitin ligase Smurf1 to facilitate virus infection by promoting the degradation of TRAF6 in teleost fish

The ubiquitin-proteasome system is one of the most important protein stability regulation systems. It can precisely regulate host immune responses by targeting signaling proteins. TRAF6 is a crucial E3 ubiquitin ligase in host antiviral signaling pathway. Here, we discovered that EF-hand domain-containing protein D2 (EFHD2) collaborated with the E3 ubiquitin ligase Smurf1 to potentiate the degradation of TRAF6, hence facilitating RNA virus Siniperca chuatsi rhabdovirus infection. The mechanism analysis revealed that EFHD2 interacted with Smurf1 and enhanced its protein stability by impairing K48-linked polyubiquitination of Smurf1, thereby promoting Smurf1-catalyzed degradation of TRAF6. This study initially demonstrated a novel mechanism by which viruses utilize host EFHD2 to achieve immune escape and provided a new perspective on the exploration of mammalian innate immunity.IMPORTANCEViruses induce host cells to activate several antiviral signaling pathways. TNF receptor-associated factor 6 (TRAF6) plays an essential role in these pathways. Numerous studies have been done on the mechanisms of TRAF6-mediated resistance to viral invasion. However, little is known about the strategies that viruses employ to antagonize TRAF6-mediated antiviral signaling pathway. Here, we discovered that EFHD2 functions as a host factor to promote viral replication. Mechanistically, EFHD2 potentiates Smurf1 to catalyze the ubiquitin-proteasomal degradation of TRAF6 by promoting the deubiquitination and stability of Smurf1, which in turn inhibits the production of proinflammatory cytokines and interferons. Our study also provides a new perspective on mammalian resistance to viral invasion.

Macrophage-expressed SRA ameliorates alcohol-induced liver injury by suppressing S-glutathionylation of Notch1 via recruiting thioredoxin

Scavenger receptor A (SRA) is preferentially expressed in macrophages and implicated as a multifunctional pattern recognition receptor for innate immunity. Hepatic macrophages play a primary role in the pathogenesis of alcoholic liver disease. Herein, we observed that SRA expression was significantly increased in the liver tissues of mice with alcohol-related liver injury. SRA-deficient (SRA-/-) mice developed more severe alcohol-induced liver disease than wild-type mice. Enhanced liver inflammation existed in alcohol-challenged SRA-/- mice and was associated with increased Notch activation in hepatic macrophages compared with wild-type control animals. Mechanistically, SRA directly bound with Notch1 and suppressed its S-glutathionylation, thereby inhibiting Notch pathway activation. Further, we determined that the SRA interacted with thioredoxin-1 (Trx-1), a redox-active protein. SRA inhibited Trx-1 dimerization and facilitated the interaction of Trx-1 with Notch1. Application of a Trx-1-specific inhibitory agent during macrophage stimulation abolished SRA-mediated regulation of the Notch pathway and its downstream targets. In summary, our study revealed that SRA plays a critical role in macrophage inflammatory response by targeting Notch1 for its glutathionylation. SRA-mediated negative regulation of Notch activation might serve as a novel therapeutic strategy for alcohol-induced liver injury.

Enhanced NF-κB activation via HIV-1 Tat-TRAF6 cross-talk

The Tat proteins of HIV-1 and simian immunodeficiency virus (SIV) are essential for activating viral transcription. In addition, Tat stimulates nuclear factor κB (NF-κB) signaling pathways to regulate viral gene expression although its molecular mechanism is unclear. Here, we report that Tat directly activates NF-κB through the interaction with TRAF6, which is an essential upstream signaling molecule of the canonical NF-κB pathway. This interaction increases TRAF6 oligomerization and auto-ubiquitination, as well as the synthesis of K63-linked polyubiquitin chains to further activate the NF-κB pathway and HIV-1 transcription. Moreover, ectopic expression of TRAF6 significantly activates HIV-1 transcription, whereas TRAF6 knockdown inhibits transcription. Furthermore, Tat-mediated activation of NF-κB through TRAF6 is conserved among HIV-1, HIV-2, and SIV isolates. Our study uncovers yet another mechanism by which HIV-1 subverts host transcriptional pathways to enhance its own transcription.

FAT10 is phosphorylated by IKKβ to inhibit the antiviral type-I interferon response

IFN-I secretion provides a rapid host defense against infection with RNA viruses. Within the host cell, viral RNA triggers the activation of the RIG-I signaling pathway, leading to the production of IFN-I. Because an exaggerated IFN-I response causes severe tissue damage, RIG-I signaling is tightly regulated. One of the factors that control the IFN-I response is the ubiquitin-like modifier FAT10, which is induced by TNF and IFNγ and targets covalently FAT10-linked proteins for proteasomal degradation. However, the mechanism of how FAT10 modulates IFN-I secretion remains to be fully elucidated. Here, we provide strong evidence that FAT10 is phosphorylated by IκB kinase β (IKKβ) upon TNF stimulation and during influenza A virus infection on several serine and threonine residues. FAT10 phosphorylation increases the binding of FAT10 to the TRAF3-deubiquitylase OTUB1 and its FAT10-mediated activation. Consequently, FAT10 phosphorylation results in a low ubiquitylation state of TRAF3, which is unable to maintain interferon regulatory factor 3 phosphorylation and downstream induction of IFN-I. Taken together, we reveal a mechanism of how phosphorylation of FAT10 limits the production of tissue-destructive IFN-I in inflammation.

Scaffold Proteins in Autoimmune Disorders

Cells transmit information to the external environment and within themselves through signaling molecules that modulate cellular activities. Aberrant cell signaling disturbs cellular homeostasis causing a number of different diseases, including autoimmunity. Scaffold proteins, as the name suggests, serve as the anchor for binding and stabilizing signaling proteins at a particular locale, allowing both intra and intercellular signal amplification and effective signal transmission. Scaffold proteins play a critical role in the functioning of tight junctions present at the intersection of two cells. In addition, they also participate in cleavage formation during cytokinesis, and in the organization of neural synapses, and modulate receptor management outcomes. In autoimmune settings such as lupus, scaffold proteins can lower the cell activation threshold resulting in uncontrolled signaling and hyperactivity. Scaffold proteins, through their binding domains, mediate protein- protein interaction and play numerous roles in cellular communication and homeostasis. This review presents an overview of scaffold proteins, their influence on the different signaling pathways, and their role in the pathogenesis of autoimmune and auto inflammatory diseases. Since these proteins participate in many roles and interact with several other signaling pathways, it is necessary to gain a thorough understanding of these proteins and their nuances to facilitate effective target identification and therapeutic design for the treatment of autoimmune disorders.

New Promising Routes in Peptic Ulcers: Toll-like Receptors and Semaphorins

Peptic ulcers (PU) are one of the commonest yet problematic diseases found to be existing in the majority of the population. Today, drugs from a wide range of therapeutic classes are available for the management of the disease. Still, the complications of the condition are difficult to tackle and the side effect profile is quite a concern. The literature indicates that Toll-like receptors (TLRs) and Semaphorins (SEMAs) have been under study for their various pharmacological actions over the past few decades. Both these signalling pathways are found to regulate immunological and inflammatory responses. Moreover, receptors and signalling molecules from the family of TLRs and SEMAs are found to have bacterial recognition and antibacterial properties which are essential in eradicating Helicobacter pylori (H. pylori), one of the major causative agents of PU. Our understanding of SEMAs, a class of proteins involved in cell signalling, is relatively less developed compared to TLRs, another class of proteins involved in the immune response. SEMAs and TLRs play different roles in biological processes, with SEMAs primarily involved in guiding cell migration and axon guidance during development, while TLRs are responsible for recognizing pathogens and initiating an immune response. Here, in this review, we will discuss in detail the signalling cascade of TLRs and SEMAs and thereby understand its association with PU for future therapeutic targeting. The review also aims at providing an overview of the study that has been into exploring the role of these signalling pathways in the management of PU.

Circular RNAs: Promising Treatment Targets and Biomarkers of Ischemic Stroke

Ischemic stroke is one of the most significant causes of morbidity and mortality worldwide. However, there is a dearth of effective drugs and treatment methods for ischemic stroke. Significant numbers of circular RNAs (circRNAs) exhibit abnormal expression following ischemic stroke and are considered potential therapeutic targets. CircRNAs have emerged as promising biomarkers due to their stable expression in peripheral blood and their potential significance in ischemic stroke diagnosis and prognosis. This review provides a summary of 31 circRNAs involved in the pathophysiological processes of apoptosis, autophagy, inflammation, oxidative stress, and angiogenesis following ischemic stroke. Furthermore, we discuss the mechanisms of action of said circRNAs and their potential clinical applications. Ultimately, circRNAs exhibit promise as both therapeutic targets and biomarkers for ischemic stroke.

The SMAC mimetic birinapant alleviates lipopolysaccharide-induced acute lung injury by inhibiting MAPK signaling

The second mitochondria-derived activator of caspases (SMAC) mimetic birinapant attenuated liver injury by inhibited the degradation of tumor necrosis factor receptor-associated factor 3 (TRAF3) and activation of mitogen-activated protein kinase (MAPK) signaling pathway in liver macrophage, but its role in LPS induced acute lung injury (ALI) is not understood. The present study was to investigate the effects of birinapant on ALI and its possible mechanism. A dose of birinapant (30 mg/kg) or a vehicle was administered intravenously 24 hours before LPS (100 μg) stimulation in mice. The levels of TNF-α, IL-6 and IL-1β in bronchoalveolar lavage fluid (BALF) were measured by ELISA. The infiltrated macrophages and expression of monocyte chemoattractant protein-1 (MCP-1) was determined by immunohistochemistry staining in the lung tissues. The JNK and p38 MAPK activation, protein expression and K48-linked polyubiquitination of TRAF3 were determined in alveolar macrophage cell line (MH-S cells) after 1μg/ml LPS stimulation. The results showed that the birinapant down-regulated the levels of TNF-α, IL-6 and IL-1β in the BALF. In addition, birinapant markedly inhibited macrophages infiltration and MCP-1 protein expression in lung tissues. At last, birinapant suppressed the MAPKsignaling pathway and K48-linked ubiquitinated degradation of TRAF3 in MH-S cells after LPS administration. In conclusion, the results proved that birinapant protected against LPS-induced ALI through inhibiting MAPK activation and K48-linked ubiquitination of TRAF3 in alveolar macrophages.

SARS-CoV-2 ORF3a-Mediated NF-κB Activation Is Not Dependent on TRAF-Binding Sequence

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has caused a global pandemic of Coronavirus Disease 2019 (COVID-19). Excessive inflammation is a hallmark of severe COVID-19, and several proteins encoded in the SARS-CoV-2 genome are capable of stimulating inflammatory pathways. Among these, the accessory protein open reading frame 3a (ORF3a) has been implicated in COVID-19 pathology. Here we investigated the roles of ORF3a in binding to TNF receptor-associated factor (TRAF) proteins and inducing nuclear factor kappa B (NF-κB) activation. X-ray crystallography and a fluorescence polarization assay revealed low-affinity binding between an ORF3a N-terminal peptide and TRAFs, and a dual-luciferase assay demonstrated NF-κB activation by ORF3a. Nonetheless, mutation of the N-terminal TRAF-binding sequence PIQAS in ORF3a did not significantly diminish NF-κB activation in our assay. Our results thus suggest that the SARS-CoV-2 protein may activate NF-κB through alternative mechanisms.

The Interaction of OTUB1 and TRAF3 Mediates NLRP3 Inflammasome Activity to Regulate TGF-β1-induced BEAS-2B Cell Injury

Asthma is a frequently chronic respiratory disease with inflammation and remodeling in the airway. OTUB1 has been reported to be associated with pulmonary diseases. However, the role and potential mechanism of OTUB1 in asthma remain unclear. The expressions of OTUB1 in the bronchial mucosal tissues of asthmatic children and TGF-β1-induced BEAS-2B cells were determined. The biological behaviors were assessed in an asthma in vitro model using a loss-function approach. The contents of inflammatory cytokines were detected by ELISA kits. The related protein expressions were performed using western blot assay. Besides, the interaction between OTUB1 and TRAF3 was detected by Co-IP and ubiquitination assays. Our results showed that OTUB1 level was increased in asthmatic bronchial mucosal tissues and TGF-β1-induced BEAS-2B cells. OTUB1 knockdown promoted proliferation, inhibited apoptosis and EMT of TGF-β1-treated cells. The inhibition of OTUB1 attenuated the TGF-β1-induced inflammation and remodeling. Furthermore, OTUB1 knockdown inhibited the deubiquitination of TRAF3 and further suppressed the activation of NLRP3 inflammasome. The overexpression of TRAF3 or NLRP3 reversed the positive role of OTUB1 knockdown in TGF-β1-induced cells injury. Collectively, OTUB1 deubiquitinates TRAF3 to activate NLRP3 inflammasome, thereby leading to inflammation and remodeling of TGF-β1-induced cells, and further promoting the pathogenesis of asthma.

TMT-based quantitative proteomics reveals the targets of andrographolide on LPS-induced liver injury

BACKGROUND

Andrographolide (Andro) is a diterpenoid derived from Andrographis paniculate, which has anti-inflammatory, antibacterial, antiviral and hepatoprotective activities. Gram-negative bacterial infections can cause varying degrees of liver injury in chickens, although Andro has been shown to have a protective effect on the liver, its underlying mechanism of action and effects on liver proteins are not known.

METHODS

The toxicity of Andro on the viability of leghorn male hepatoma (LMH) cells at different concentrations and times was analyzed by CCK-8 assays. Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities in the culture supernatants were measured using an automatic biochemical analyzer to evaluate the protective effect of androscopolide on LPS-induced injury of LMH cells. Subsequently, TMT proteomics analysis were performed on the negative control group (NC group), LPS, and LPS-Andro groups, and bioinformatics analysis was performed on the differentially expressed proteins (DEPs).

RESULTS

It was found that Andro reduced ALT and AST levels in the cell supernatant and alleviated LPS-induced injury in LMH cells. Proteomic analysis identified 50 and 166 differentially expressed proteins in the LPS vs. NC group and LPS-Andro vs. LPS group, respectively. Andro may be involved in steroid metabolic processes, negative regulation of MAPK cascade, oxidative stress, and other processes to protect against LPS-induced liver injury.

CONCLUSIONS

Andro protects against LPS-induced liver injury, HMGCS1, HMGCR, FDPS, PBK, CAV1, PRDX1, PRDX4, and PRDX6, which were identified by differential proteomics, may be the targets of Andro. Our study may provide new theoretical support for Andro protection against liver injury.

Effects of TRAF3 on the proliferation and migration of lung adenocarcinoma depend partly on pyroptosis

BACKGROUND

Tumor necrosis factor receptor-associated factor 3 (TRAF3) has specific regulatory effects on a wide range of diseases, including tumors. However, the effect and mechanism of TRAF3 on lung adenocarcinoma (LUAD) are still unknown. The aim of the present study was to make clear the role and potential mechanism of TRAF3 in LUAD.

METHODS

TIMER2.0 database and western blot were applied to detect the expression of TRAF3 in lung adenocarcinoma tissue. Kaplan-Meier Plotter database was utilized to explore the effect of TRAF3 on the clinical prognosis of lung adenocarcinoma patients. Specific siRNA was used to inhibit the expression of TRAF3 in LUAD cells (A549 and H1299). CCK-8 and EdU assays were performed for assessing LUAD cells proliferation. Wound healing assay and transwell assay were performed for determining cells migration. CCK-8 assay was used to assess the response of the LUAD cells to paclitaxel. TIMER2.0 bioinformatics and western blot were employed to detect the effects of TRAF3 on pyroptosis in LUAD.

RESULTS

TRAF3 was highly expressed in lung adenocarcinoma tissues and cell lines. Patients with TRAF3 hyperexpression had a good prognosis compared to those with lower expression. TRAF3 inhibition notably induced proliferation and migration of LUAD cells. Inhibition of TRAF3 also weakened the sensitivity of LUAD cells to paclitaxel. Moreover, bioinformatics results showed that TRAF3 was positively correlated with the expression of pyroptosis-related genes in LUAD. Western blot assays showed that TRAF3 inhibition visibly decreased the expression of apoptosis-associated speck-like protein (ASC), cleaved caspase-1 and matured- IL-1β.

CONCLUSIONS

Inhibition of TRAF3 promotes the proliferation and migration of LUAD cells, and reduces the sensitivity of LUAD cells to paclitaxel. The effects of TRAF3 on LUAD cells were mediated in part by caspase-1-dependent pyroptosis.

Influence of Race and High Laminar Shear Stress on TNFR1 Signaling in Endothelial Cells

Tumor necrosis factor (TNF) binding to endothelial TNF receptor-I (TNFR-I) facilitates monocyte recruitment and chronic inflammation, leading to the development of atherosclerosis. In vitro data show a heightened inflammatory response and atherogenic potential in endothelial cells (ECs) from African American (AA) donors. High laminar shear stress (HSS) can mitigate some aspects of racial differences in endothelial function at the cellular level. We examined possible racial differences in TNF-induced monocyte adhesion and TNFR1 signaling complex expression/activity, along with the effects of HSS. Tohoku Hospital Pediatrics-1 (THP-1) monocytes were used in a co-culture system with human umbilical vein ECs (HUVECs) from Caucasian American (CA) and AA donors to examine racial differences in monocyte adhesion. An in vitro exercise mimetic model was applied to investigate the potential modulatory effect of HSS. THP-1 adherence to ECs and TNF-induced nuclear factor kappa B (NF-κB) DNA binding were elevated in AA ECs compared to CA ECs, but not significantly. We report no significant racial differences in the expression of the TNFR-I signaling complex. Application of HSS significantly increased the expression and shedding of TNFR-I and the expression of TRAF3, and decreased the expression of TRAF5 in both groups. Our data does not support TNF-induced NF-κB activation as a potential mediator of racial disparity in this model. Other pathways and associated factors activated by the TNFR1 signaling complex are recommended targets for future research.

TRAF3 deficiency in MDCK cells improved sensitivity to the influenza A virus

Tumor necrosis factor receptor-associated factor 3 (TRAF3), an adaptor protein, has significant and varying effects on immunity depending on cell types. The role of TRAF3 in Madin-Darby Canine Kidney Epithelial (MDCK) cell resistance to influenza A virus (IVA) remains elusive. In the present study, CRISPR-Cas9 gene editing technology was used to construct the TRAF3 knockout MDCK cells (MDCK-TRAF3-/-). Hemagglutination assay, plaque assay, transcriptome, and quantitative real-time PCR were performed after IVA infection. The results showed that after IVA infection, HA titers and virus titers were promoted, interferon I-related pathways were significantly blocked, and transcription of several antiviral-related genes was significantly decreased in MDCK-TRAF3-/- cells. Thus, our study suggests that TRAF3 gene knockout reduced MDCK cell's resistance to IVA, thereby resulting in a promising way for IVA isolation and vaccine manufacturing.

Regulation of type I IFN responses by deubiquitinating enzyme A in inflammatory bowel diseases

The development of Inflammatory bowel disease (IBD) is driven by excessive production of pro-inflammatory cytokines including TNF-α, IL-12, and IL-23. This notion is supported by the remarkable clinical success of biologics targeting these cytokines. Recognition of cell wall components derived from intestinal bacteria by Toll-like receptors (TLRs) induces the production of these pro-inflammatory cytokines by macrophages and dendritic cells in human IBD and experimental colitis model. Although sensing of bacterial nucleic acids by endosomal TLRs, specifically TLR3, TLR7, and TLR9 leads to robust production of type I IFNs, it remains debatable whether TLR-mediated type I IFN responses are pathogenic or protective in IBD patients. Additionally, recent studies identified deubiquitinating enzyme A (DUBA) as a novel negative regulator of TLR-mediated type I IFN responses. In light of these observations and their potential applications, in this review, we summarize recent findings on the roles of type I IFN responses and DUBA-mediated negative regulation of these responses in human IBD and experimental colitis model.

IRF5 promotes glycolysis in the progression of hepatocellular carcinoma and is regulated by TRIM35

OBJECTIVES

The interferon regulatory factor (IRF) family of proteins are involved in tumor progression. However, the role of IRF5 in tumorigenesis remains unknown. In this study we aimed to elucidate the functions of IRF5 in the progression of hepatocellular carcinoma (HCC).

METHODS

IRF5 expression in HCC was analyzed through quantitative polymerase chain reaction (qPCR), western blot, and immunohistochemistry (IHC), etc. The Cell Counting Kit 8 (CCK8) assay, anchorage-independent assay, and EdU assay were used to evaluate the role of IRF5. The molecular mechanisms were studied by analyzing the metabolites with mass spectrum and immunoprecipitation.

RESULTS

IRF5 was upregulated in HCC. Interfering with IRF5 inhibited the proliferation and tumorigenic potential of HCC cells. When studying the molecular mechanism, IRF5 was found to upregulate the expression of lactate dehydrogenase A (LDHA) and promoted glycolysis. Additionally, tripartite motif containing 35 (TRIM35) interacted with IRF5, promoting its ubiquitination and degradation. In the clinically obtained HCC samples, TRIM35 was negatively correlated with the expression of IRF5.

CONCLUSION

These findings reveal the oncogenic function of IRF5 in the progression of HCC by enhancing glycolysis, further supporting the potential of IRF5 as a viable target for HCC therapy.

Targeted inhibition of PTPN22 is a novel approach to alleviate osteogenic responses in aortic valve interstitial cells and aortic valve lesions in mice

BACKGROUND

Calcific aortic valve disease (CAVD) is the most prevalent valvular disease and has high morbidity and mortality. CAVD is characterized by complex pathophysiological processes, including inflammation-induced osteoblastic differentiation in aortic valve interstitial cells (AVICs). Novel anti-CAVD agents are urgently needed. Protein tyrosine phosphatase nonreceptor type 22 (PTPN22), an intracellular nonreceptor-like protein tyrosine phosphatase, is involved in several chronic inflammatory diseases, including rheumatoid arthritis and diabetes. However, it is unclear whether PTPN22 is involved in the pathogenesis of CAVD.

METHODS

We obtained the aortic valve tissue from human and cultured AVICs from aortic valve. We established CAVD mice model by wire injury. Transcriptome sequencing, western bolt, qPCR, and immunofluorescence were performed to elucidate the molecular mechanisms.

RESULTS

Here, we determined that PTPN22 expression was upregulated in calcific aortic valve tissue, AVICs treated with osteogenic medium, and a mouse model of CAVD. In vitro, overexpression of PTPN22 induced osteogenic responses, whereas siRNA-mediated PTPN22 knockdown abolished osteogenic responses and mitochondrial stress in the presence of osteogenic medium. In vivo, PTPN22 ablation ameliorated aortic valve lesions in a wire injury-induced CAVD mouse model, validating the pathogenic role of PTPN22 in CAVD. Additionally, we discovered a novel compound, 13-hydroxypiericidin A 10-O-α-D-glucose (1 → 6)-β-D-glucoside (S18), in a marine-derived Streptomyces strain that bound to PTPN22 with high affinity and acted as a novel inhibitor. Incubation with S18 suppressed osteogenic responses and mitochondrial stress in human AVICs induced by osteogenic medium. In mice with aortic valve injury, S18 administration markedly alleviated aortic valve lesions.

CONCLUSION

PTPN22 plays an essential role in the progression of CAVD, and inhibition of PTPN22 with S18 is a novel option for the further development of potent anti-CAVD drugs. Therapeutic inhibition of PTPN22 retards aortic valve calcification through modulating mitochondrial dysfunction in AVICs.

Triad3A involved in the regulation of endotoxin tolerance and mycobactericidal activity through the NFκB-nitric oxide pathway

INTRODUCTION

Sepsis is characterized by an endotoxin tolerance phenotype that occurs in the stage of infection. Persistent bacterial infection can lead to immune cell exhaustion. Triad3A, an E3 ubiquitin ligase, negatively regulates its activation by TLR4. However, the effect of Triad3A on endotoxin tolerance and bactericidal ability in the state of endotoxin tolerance remains unclear.

METHODS

Using single dose LPS and repeated LPS stimulated macrophage cell lines at indicated times, we investigated miR-191, Tirad3A, TRAF3, TLR4, p-P65, TNF-α, IL-1β, and iNOS expression, the effect of miR-191 on Triad3A and TRAF3, gene loss-of-function analyses, the effect of Triad3A on TLR4, p-P65, cytokine, and mycobactericidal activity in endotoxin tolerant cells infected with Mycobacterium marinum.

RESULTS

Here we found that Triad3A is involved in regulating endotoxin tolerance. Our result also displayed that miR-191 expression is downregulated in macrophages in the state of endotoxin tolerance. miR-191 can directly bind to Triad3A and TRAF3. Additionally, knockdown of Triad3A can reverse the effect of decreasing TNF-α and IL-1β in endotoxin tolerant macrophages. Furthermore, we demonstrated that the TLR4-NF-κB-NO pathway was associated with Triad3A and responsible for the killing of intracellular mycobacteria in a tuberculosis sepsis model.

CONCLUSIONS

These results provide new insight into the mechanisms of Triad3A induced tolerogenic phenotype in macrophages, which can help the better comprehension of the pathogenesis involved in septic shock with infection of Mycobacterium tuberculosis, and suggest that Triad3A may be a potential drug target for the treatment of severe septic tuberculosis.

Resolvins and cysteinyl-containing pro-resolving mediators activate resolution of infectious inflammation and tissue regeneration

This review is a synopsis of the main points from the opening presentation by the authors in the Resolution of Inflammation session at the 8th European Workshop on Lipid Mediators held at the Karolinska Institute, Stockholm, Sweden, June 29th, 2022. Specialized pro-resolving mediators (SPM) promote tissue regeneration, control infections and resolution of inflammation. These include resolvins, protectins, maresins and the newly identified conjugates in tissue regeneration (CTRs). We reported mechanisms of CTRs in activating primordial regeneration pathways in planaria using RNA-sequencing. Also, the 4S,5S-epoxy-resolvin intermediate in the biosynthesis of resolvin D3 and resolvin D4 was prepared by total organic synthesis. Human neutrophils convert this to resolvin D3 and resolvin D4, while human M2 macrophages transformed this labile epoxide intermediate to resolvin D4 and a novel cysteinyl-resolvin that is a potent isomer of RCTR1. The novel cysteinyl-resolvin significantly accelerates tissue regeneration with planaria and inhibits human granuloma formation.

Genome-wide identification of TNF receptor-associated factors in Japanese flounder (Paralichthys olivaceus) and functional analysis of resistance to temperature and Edwardsiella tarda stress

Tumor necrosis factor receptor-associated factors (TRAFs), as the signaling mediators of the tumor necrosis factor (TNFR) superfamily, toll-like receptors (TLR) and interleukin-1 receptor (IL-1R) superfamily, can activate downstream signal transduction pathways and play an important role in the body's immune process. In this study, six TRAF genes, namely PoTRAF2a, PoTRAF2b, PoTRAF3, PoTRAF4, PoTRAF6 and PoTRAF7, were identified and annotated in Japanese flounder by using bioinformatics methods. Phylogenetic analysis confirmed that TRAF genes can be divided into seven groups. Analysis of motif composition and gene structure demonstrated that all PoTRAF members were evolutionarily conserved. The expression patterns of PoTRAF genes were then further investigated in six different developmental stages and eleven tissues of healthy fish, and it was found that there were spatial and tissue specificities among the members. To investigate the immune response of Japanese flounder to abiotic and biotic stresses, we further analyzed the expression profile of PoTRAFs after temperature stress and pathogen challenge. The result showed that PoTRAF3 and PoTRAF4 were observably differentially expressed under temperature stress, indicating that they were involved in the immune response after temperature stress. The expression of PoTRAF2a, PoTRAF2b and PoTRAF4 was significantly different after E. tarda infection, suggesting that they might have antibacterial effects. These results would help to clarify the molecular roles of PoTRAF genes in the regulation of immune and inflammatory responses in Japanese flounder.

Disentangling the Pathogenesis of Systemic Lupus Erythematosus: Close Ties between Immunological, Genetic and Environmental Factors

Systemic Lupus Erythematosus (SLE) is a systemic autoimmune disease that attacks various organ systems with a variety of clinical implications, ranging from mild skin and mucosal manifestations to severe central nervous system manifestations and death. Cases of SLE have been documented nearly two centuries ago when scholars used the terms 'erythema centrifugum' and 'seborrhea congestiva' to describe the discoid skin lesions and the butterfly or malar rash in SLE. Since then, knowledge about this disease has developed rapidly, especially knowledge related to the underlying pathogenesis of SLE. To date, it is known that immune system dysregulation, supported by genetic and environmental predisposition, can trigger the occurrence of SLE in a group of susceptible individuals. Various inflammatory mediators, cytokines and chemokines, as well as intra- and intercellular signaling pathways, are involved in the pathogenesis of SLE. In this review, we will discuss the molecular and cellular aspects of SLE pathogenesis, with a focus on how the immune system, genetics and the environment interact and trigger the various clinical manifestations of SLE.

Stony coral tissue loss disease induces transcriptional signatures of in situ degradation of dysfunctional Symbiodiniaceae

Stony coral tissue loss disease (SCTLD), one of the most pervasive and virulent coral diseases on record, affects over 22 species of reef-building coral and is decimating reefs throughout the Caribbean. To understand how different coral species and their algal symbionts (family Symbiodiniaceae) respond to this disease, we examine the gene expression profiles of colonies of five species of coral from a SCTLD transmission experiment. The included species vary in their purported susceptibilities to SCTLD, and we use this to inform gene expression analyses of both the coral animal and their Symbiodiniaceae. We identify orthologous coral genes exhibiting lineage-specific differences in expression that correlate to disease susceptibility, as well as genes that are differentially expressed in all coral species in response to SCTLD infection. We find that SCTLD infection induces increased expression of rab7, an established marker of in situ degradation of dysfunctional Symbiodiniaceae, in all coral species accompanied by genus-level shifts in Symbiodiniaceae photosystem and metabolism gene expression. Overall, our results indicate that SCTLD infection induces symbiophagy across coral species and that the severity of disease is influenced by Symbiodiniaceae identity.

Long noncoding RNA LTCONS6801 up-regulates TBK1 mediated antiviral innate immunity in miiuy croaker, Miichttys miiuy

The development of seuencing technology has further accelerated the research of noncoding RNA (ncRNA). A large number of studies have shown that long noncoding RNA (lncRNA) in ncRNA can regulate gene expression in various ways and then affect various physiological and biochemical processes of the host. In this study, we found a novel lncRNA in Miichthys miiuy, named LTCONS6801, which is beneficial to TANK-binding kinase 1 (TBK1) and its -mediated pathway to promote the host immune function. First, we found that lncRNA LTCONS6801 can enhance cell activity through cell activity detection and cell proliferation detection. Besides, after poly (I: C) stimulation, overexpression of lncRNA LTCONS6801 promoted the expression of antiviral gene and TBK1. We found that lncRNA LTCONS6801 further affects NF-κB and IRF3 signaling pathways by regulating the expression of TBK1. In short, lncRNA LTCONS6801 is an lncRNA that can positively regulate the host innate immune response by regulating the expression of TBK1. Our study enriches the theory and insight of lncRNA regulating antiviral immune pathway and clarifies the important role of lncRNA in antiviral immunity of teleost fish.

Investigating the relationship between depression and breast cancer: observational and genetic analyses

BACKGROUND

Both depression and breast cancer (BC) contribute to a substantial global burden of morbidity and mortality among women, and previous studies have observed a potential depression-BC link. We aimed to comprehensively characterize the phenotypic and genetic relationships between depression and BC.

METHODS

We first evaluated phenotypic association using longitudinal follow-up data from the UK Biobank (N = 250,294). We then investigated genetic relationships leveraging summary statistics from the hitherto largest genome-wide association study of European individuals conducted for depression (N = 500,199), BC (N = 247,173), and its subtypes based on the status of estrogen receptor (ER + : N = 175,475; ER - : N = 127,442).

RESULTS

Observational analysis suggested an increased hazard of BC in depression patients (HR = 1.10, 95%CIs = 0.95-1.26). A positive genetic correlation between depression and overall BC was observed ([Formula: see text] = 0.08, P = 3.00 × 10-4), consistent across ER + ([Formula: see text] = 0.06, P = 6.30 × 10-3) and ER - subtypes ([Formula: see text] = 0.08, P = 7.20 × 10-3). Several specific genomic regions showed evidence of local genetic correlation, including one locus at 9q31.2, and four loci at, or close, to 6p22.1. Cross-trait meta-analysis identified 17 pleiotropic loci shared between depression and BC. TWAS analysis revealed five shared genes. Bi-directional Mendelian randomization suggested risk of depression was causally associated with risk of overall BC (OR = 1.12, 95%Cis = 1.04-1.19), but risk of BC was not causally associated with risk of depression.

CONCLUSIONS

Our work demonstrates a shared genetic basis, pleiotropic loci, and a putative causal relationship between depression and BC, highlighting a biological link underlying the observed phenotypic relationship; these findings may provide important implications for future studies aimed reducing BC risk.

TRAF3 suppression encourages B cell recruitment and prolongs survival of microbiome-intact mice with ovarian cancer

BACKGROUND

Ovarian cancer (OC) is known for exhibiting low response rates to immune checkpoint inhibitors that activate T cells. However, immunotherapies that activate B cells have not yet been extensively explored and may be a potential target, as B cells that secrete immunoglobulins have been associated with better outcomes in OC. Although the secretion of immunoglobulins is often mediated by the microbiome, it is still unclear what role they play in limiting the progression of OC.

METHODS

We conducted an in-vivo CRISPR screen of immunodeficient (NSG) and immune-intact wild type (WT) C57/BL6 mice to identify tumor-derived immune-escape mechanisms in a BRAC1- and TP53-deficient murine ID8 OC cell line (designated ITB1). To confirm gene expression and signaling pathway activation in ITB1 cells, we employed western blot, qPCR, immunofluorescent staining, and flow cytometry. Flow cytometry was also used to identify immune cell populations in the peritoneum of ITB1-bearing mice. To determine the presence of IgA-coated bacteria in the peritoneum of ITB1-bearing mice and the ascites of OC patients, we employed 16S sequencing. Testing for differences was done by using Deseq2 test and two-way ANOVA test. Sequence variants (ASVs) were produced in Qiime2 and analyzed by microeco and phyloseq R packages.

RESULTS

We identified tumor necrosis factor receptor-associated factor 3 (TRAF3) as a tumor-derived immune suppressive mediator in ITB1 cells. Knockout of TRAF3 (TRAF3KO) activated the type-I interferon pathway and increased MHC-I expression. TRAF3KO tumors exhibited a growth delay in WT mice vs. NSG mice, which was correlated with increased B cell infiltration and activation compared to ITB1 tumors. B cells were found to be involved in the progression of TRAF3KO tumors, and B-cell surface-bound and secreted IgA levels were significantly higher in the ascites of TRAF3KO tumors compared to ITB1. The presence of commensal microbiota was necessary for B-cell activation and for delaying the progression of TRAF3KO tumors in WT mice. Lastly, we observed unique profiles of IgA-coated bacteria in the ascites of OC-bearing mice or the ascites of OC patients.

CONCLUSIONS

TRAF3 is a tumor-derived immune-suppressive modulator that influences B-cell infiltration and activation, making it a potential target for enhancing anti-tumor B-cell responses in OC.

Characterization of TRAF genes and their responses to Vibrio anguillarum challenge in Argopecten scallops

The tumor necrosis factor receptor-related factor (TRAF) family has been reported to be involved in many immune pathways, such as TNFR, TLR, NLR, and RLR in animals. However, little is known about the roles of TRAF genes in the innate immune of Argopecten scallops. In this study, we first identified five TRAF genes, including TRAF₂, TRAF₃, TRAF₄, TRAF₆ and TRAF₇, but not TRAF₁ and TRAF₅, from both the bay scallop A. irradians (Air) and the Peruvian scallop A. purpuratus (Apu). The phylogenetic analysis showed that the TRAF genes in Argopecten scallops (AiTRAF) belong to the branch of molluscan TRAF family, which lacks TRAF₁ and TRAF₅. Since TRAF₆ is a key bridge factor in the tumor necrosis factor superfamily and plays an important role in innate and adaptive immunity, we cloned the ORFs of the TRAF₆ gene in both A. irradians and A. purpuratus, as well as in two reciprocal hybrids (Aip for the hybrid Air × Apu and Api for the hybrid Apu × Air). Differences in conformational and post-translational modification resulted from the variation in amino acid sequences may cause differences in activity among them. Analysis of conserved motifs and protein structural domains revealed that AiTRAF contains typical structural domains similar to those of other mollusks and has the same conserved motifs. Tissue expression of TRAF in Argopecten scallops challenged by Vibrio anguillarum was examined by qRT-PCR. The results showed that AiTRAF were higher in gill and hepatopancreas. When challenged by Vibrio anguillarum, the expression of AiTRAF was significantly increased compared with the control group, indicating that AiTRAF may play an important role in the immunity of scallops. In addition, the expression of TRAF was higher in Api and Aip than in Air when challenged by Vibrio anguillarum, suggesting that TRAF may have contributed to the high resistance of Api and Aip to Vibrio anguillarum. The results of this study may provide new insights into the evolution and function of TRAF genes in bivalves and ultimately benefit scallop breeding.

Leucine supplementation alleviates immune and antioxidant function damage in adult rats induced by early weaning

BACKGROUND

Early weaning (EW) can lead to stress and destroy intestinal integrity. Leucine has functional diversity in antioxidant, immune, and metabolic regulation.

OBJECTIVE

This study aims to explore a lifelong impact of early weaning on intestinal, immune and antioxidant functions of adult rats and the role of leucine supplementation in the alleviation of the damage caused by early weaning.

METHODS

In this 211-day study, 36 SD rat pups were divided into three groups: 21-day weaning normal group (C), 17-day early weaning group (E) and 17-day early weaning group with two-month leucine supplementation (EL). The content of amino acids in serum, immune and antioxidant indexes, intestinal morphology, liver transcriptomics, mRNA, and protein expression of signaling pathway were determined.

RESULTS

EW reduced the protein expression level of sIgA and GSH in jejunum, and increased the protein expression levels of IgA, IgM, and IL-17 in serum, and TNFα and IL-1β in jejunum. The impairment by EW was activated via NF-κB signal pathway. In terms of antioxidation, EW reduced the level of GSH in jejunum. After leucine supplementation, the damage induced by EW was partially repaired.

CONCLUSIONS

EW causes long-term damage to the intestinal barrier function, immunity, apoptosis factor, and antioxidant function of rats and leucine supplementation could alleviate the impairment, suggesting possible approach to EW.

FXYD3 enhances IL-17A signaling to promote psoriasis by competitively binding TRAF3 in keratinocytes

Psoriasis is a common chronic inflammatory skin disease characterized by inflammatory cell infiltration and epidermal hyperplasia. However, the regulatory complexity of cytokine and cellular networks still needs to be investigated. Here, we show that the expression of FXYD3, a member of the FXYD domain-containing regulators of Na+/K+ ATPases family, is significantly increased in the lesional skin of psoriasis patients and mice with imiquimod (IMQ)-induced psoriasis. IL-17A, a cytokine important for the development of psoriatic lesions, contributes to FXYD3 expression in human primary keratinocytes. FXYD3 deletion in keratinocytes attenuated the psoriasis-like phenotype and inflammation in an IMQ-induced psoriasis model. Importantly, FXYD3 promotes the formation of the IL-17R-ACT1 complex by competing with IL-17R for binding to TRAF3 and then enhances IL-17A signaling in keratinocytes. This promotes the activation of the NF-κB and MAPK signaling pathways and leads to the expression of proinflammatory factors. Our results clarify the mechanism by which FXYD3 serves as a mediator of IL-17A signaling in keratinocytes to form a positive regulatory loop to promote psoriasis exacerbation. Targeting FXYD3 may serve as a potential therapeutic approach in the treatment of psoriasis.

TRAF3 activates STING-mediated suppression of EV-A71 and target of viral evasion

Innate immunity represents one of the main host responses to viral infection.^1-3 STING (Stimulator of interferon genes), a crucial immune adapter functioning in host cells, mediates cGAS (Cyclic GMP-AMP Synthase) sensing of exogenous and endogenous DNA fragments and generates innate immune responses.⁴ Whether STING activation was involved in infection and replication of enterovirus remains largely unknown. In the present study, we discovered that human enterovirus A71 (EV-A71) infection triggered STING activation in a cGAS dependent manner. EV-A71 infection caused mitochondrial damage and the discharge of mitochondrial DNA into the cytosol of infected cells. However, during EV-A71 infection, cGAS-STING activation was attenuated. EV-A71 proteins were screened and the viral protease 2A^pro had the greatest capacity to inhibit cGAS-STING activation. We identified TRAF3 as an important factor during STING activation and as a target of 2A^pro. Supplement of TRAF3 rescued cGAS-STING activation suppression by 2A^pro. TRAF3 supported STING activation mediated TBK1 phosphorylation. Moreover, we found that 2A^pro protease activity was essential for inhibiting STING activation. Furthermore, EV-D68 and CV-A16 infection also triggered STING activation. The viral protease 2A^pro from EV-D68 and CV-A16 also had the ability to inhibit STING activation. As STING activation prior to EV-A71 infection generated cellular resistance to EV-A71 replication, blocking EV-A71-mediated STING suppression represents a new anti-viral target.

Activation of nucleotide-binding oligomerization domain 2 by muramyl dipeptide negatively regulates Toll-like receptor 9-mediated colonic inflammation through the induction of deubiquitinating enzyme A expression

Mutations in nucleotide-binding oligomerization domain 2 (NOD2) are associated with Crohn's disease (CD). Although NOD2 activation contributes to the maintenance of intestinal homeostasis through the negative regulation of pro-inflammatory cytokine responses mediated by Toll-like receptors (TLRs), the effects of NOD2 activation on interferon (IFN)-α responses induced by TLR9 have been poorly defined. To explore the cross-talk between NOD2 and TLR9, human monocytes or dendritic cells (DCs) were stimulated with NOD2 and/or TLR9 ligands to measure IFN-α production. The severity of dextran sodium sulfate (DSS)-induced colitis was compared in mice treated with NOD2 and/or TLR9 ligands. Expression of IFN-α and IFN-stimulated genes (ISGs) was examined in the colonic mucosa of patients with inflammatory bowel disease (IBD). NOD2 activation reduced TLR9-induced IFN-α production by monocytes and DCs in a deubiquitinating enzyme A (DUBA)-dependent manner. Activation of DUBA induced by the co-stimulation of TLR9 and NOD2 inhibited Lys63-linked polyubiquitination of TRAF3 and suppressed TLR9-mediated IFN-α production. NOD2 activation in hematopoietic cells protected mice from TLR9-induced exacerbation of DSS-induced colitis by down-regulating IFN-α responses and up-regulating DUBA expression. Colonic mucosa of patients with active and remitted IBD phases was characterized by the enhanced and reduced expression of ISGs, respectively. Expression levels of IFN-α and IL-6 positively correlated in the active colonic mucosa of patients with ulcerative colitis and CD, whereas DUBA expression inversely correlated with that of IFN-α in patients with CD. Collectively, these data suggest that DUBA-dependent negative effect of NOD2 on TLR9-mediated IFN-α responses contributes to the maintenance of intestinal homeostasis.

TNF receptor-related factor 3 inactivation promotes the development of intrahepatic cholangiocarcinoma through NF-κB-inducing kinase-mediated hepatocyte transdifferentiation

BACKGROUND AND AIMS

Intrahepatic cholangiocarcinoma (ICC) is a deadly but poorly understood disease, and its treatment options are very limited. The aim of this study was to identify the molecular drivers of ICC and search for therapeutic targets.

APPROACH AND RESULTS

We performed a Sleeping Beauty transposon-based in vivo insertional mutagenesis screen in liver-specific Pten -deficient mice and identified TNF receptor-related factor 3 ( Traf3 ) as the most significantly mutated gene in murine ICCs in a loss-of-function manner. Liver-specific Traf3 deletion caused marked cholangiocyte overgrowth and spontaneous development of ICC in Pten knockout and KrasG12D mutant mice. Hepatocyte-specific, but not cholangiocyte-specific, Traf3 -deficient and Pten -deficient mice recapitulated these phenotypes. Lineage tracing and single-cell RNA sequencing suggested that these ICCs were derived from hepatocytes through transdifferentiation. TRAF3 and PTEN inhibition induced a transdifferentiation-like phenotype of hepatocyte-lineage cells into proliferative cholangiocytes through NF-κB-inducing kinase (NIK) up-regulation in vitro. Intrahepatic NIK levels were elevated in liver-specific Traf3 -deficient and Pten -deficient mice, and NIK inhibition alleviated cholangiocyte overgrowth. In human ICCs, we identified an inverse correlation between TRAF3 and NIK expression, with low TRAF3 or high NIK expression associated with poor prognosis. Finally, we showed that NIK inhibition by a small molecule inhibitor or gene silencing suppressed the growth of multiple human ICC cells in vitro and ICC xenografts in vivo.

CONCLUSIONS

TRAF3 inactivation promotes ICC development through NIK-mediated hepatocyte transdifferentiation. The oncogenic TRAF3-NIK axis may be a potential therapeutic target for ICC.

A novel TBK1/IKKϵ is involved in immune response and interacts with MyD88 and MAVS in the scallop Chlamys farreri

Inhibitor of κB kinase (IKK) family proteins are key signaling molecules in the animal innate immune system and are considered master regulators of inflammation and innate immunity that act by controlling the activation of transcription factors such as NF-κB. However, few functional studies on IKK in invertebrates have been conducted, especially in marine mollusks. In this study, we cloned the IKK gene in the Zhikong scallop Chlamys farreri and named it CfIKK3. CfIKK3 encodes a 773-amino acid-long protein, and phylogenetic analysis showed that CfIKK3 belongs to the invertebrate TBK1/IKKϵ protein family. Quantitative real-time PCR analysis showed that CfIKK3 mRNA is ubiquitously expressed in all tested scallop tissues. The expression of CfIKK3 transcripts was significantly induced after challenge with lipopolysaccharide, peptidoglycan, or poly(I:C). Co-immunoprecipitation (co-IP) assays confirmed the direct interaction of CfIKK3 with MyD88 (the key adaptor in the TLR pathway) and MAVS (the key adaptor in the RLR pathway), suggesting that this IKK protein plays a crucial role in scallop innate immune signal transduction. In addition, the CfIKK3 protein formed homodimers and bound to CfIKK2, which may be a key step in the activation of its own and downstream transcription factors. Finally, in HEK293T cells, dual-luciferase reporter gene experiments showed that overexpression of CfIKK3 protein activated the NF-κB reporter gene in a dose-dependent manner. In conclusion, our experimental results confirmed that CfIKK3 could respond to PAMPs challenge and participate in scallop TLR and RLR pathway signaling, ultimately activating NF-κB. Therefore, as a key signaling molecule and modulator of immune activity, CfIKK3 plays an important role in the innate immune system of scallops.

Toll-like Receptors and Thrombopoiesis

Platelets are the second most abundant blood component after red blood cells and can participate in a variety of physiological and pathological functions. Beyond its traditional role in hemostasis and thrombosis, it also plays an indispensable role in inflammatory diseases. However, thrombocytopenia is a common hematologic problem in the clinic, and it presents a proportional relationship with the fatality of many diseases. Therefore, the prevention and treatment of thrombocytopenia is of great importance. The expression of Toll-like receptors (TLRs) is one of the most relevant characteristics of thrombopoiesis and the platelet inflammatory function. We know that the TLR family is found on the surface or inside almost all cells, where they perform many immune functions. Of those, TLR2 and TLR4 are the main stress-inducing members and play an integral role in inflammatory diseases and platelet production and function. Therefore, the aim of this review is to present and discuss the relationship between platelets, inflammation and the TLR family and extend recent research on the influence of the TLR2 and TLR4 pathways and the regulation of platelet production and function. Reviewing the interaction between TLRs and platelets in inflammation may be a research direction or program for the treatment of thrombocytopenia-related and inflammatory-related diseases.

TRAF3: A novel regulator of mitochondrial physiology and metabolic pathways in B lymphocytes

Mitochondria, the organelle critical for cell survival and metabolism, are exploited by cancer cells and provide an important therapeutic target in cancers. Mitochondria dynamically undergo fission and fusion to maintain their diverse functions. Proteins controlling mitochondrial fission and fusion have been recognized as essential regulators of mitochondrial functions, mitochondrial quality control, and cell survival. In a recent proteomic study, we identified the key mitochondrial fission factor, MFF, as a new interacting protein of TRAF3, a known tumor suppressor of multiple myeloma and other B cell malignancies. This interaction recruits the majority of cytoplasmic TRAF3 to mitochondria, allowing TRAF3 to regulate mitochondrial morphology, mitochondrial functions, and mitochondria-dependent apoptosis in resting B lymphocytes. Interestingly, recent transcriptomic, metabolic and lipidomic studies have revealed that TRAF3 also vitally regulates multiple metabolic pathways in B cells, including phospholipid metabolism, glucose metabolism, and ribonucleotide metabolism. Thus, TRAF3 emerges as a novel regulator of mitochondrial physiology and metabolic pathways in B lymphocytes and B cell malignancies. Here we review current knowledge in this area and discuss relevant clinical implications.

Structure of fish TRAF4 and its implication in TRAF4-mediated immune cell and platelet signaling

Due to an increasing interest in immunity and signal transduction in teleost fish, important key signaling molecules associated with the immune response, including TRAF molecules, have been recently cloned and characterized. To better understand the role of TRAF4 in fish immune signaling and compare it with the human system, our study cloned the TRAF4 gene from the Antarctic yellowbelly rockcod Notothenia coriiceps (ncTRAF4) and purified the protein. Here, we report the first crystal structure of teleost fish TRAF4. Based on biochemical characterization, our findings elucidated the mechanisms through which signaling molecules gain cold adaptivity. Additionally, we identified a platelet receptor GPIbβ homolog in N. coriiceps (ncGPIbβ) and found that the "RRFERLFKEARRTS" region of this homolog directly binds to ncTRAF4, indicating that ncTRAF4 also recognizes the "RLXA" motif for receptor interactions and further TARF4-mediated cellular signaling. Collectively, our findings provide novel insights into the mechanisms of TRAF4-mediated immune cell and platelet signaling in fish and the structural flexibility-mediated cold adaptiveness of signaling molecules.

African Swine Fever Virus Host-Pathogen Interactions

African swine fever virus is a complex double-stranded DNA virus that exhibits tropism for cells of the mononuclear phagocytic system. Virus replication is a multi-step process that involves the nucleus of the host cell as well the formation of large perinuclear sites where progeny virions are assembled prior to transport to, and budding through, the plasma membrane. Like many viruses, African swine fever virus reorganises the cellular architecture to facilitate its replication and has evolved multiple mechanisms to avoid the potential deleterious effects of host cell stress response pathways. However, how viral proteins and virus-induced structures trigger cellular stress pathways and manipulate the subsequent responses is still relatively poorly understood. African swine fever virus alters nuclear substructures, modulates autophagy, apoptosis and the endoplasmic reticulum stress response pathways. The viral genome encodes for at least 150 genes, of which approximately 70 are incorporated into the virion. Many of the non-structural genes have not been fully characterised and likely play a role in host range and modifying immune responses. As the field moves towards approaches that take a broader view of the effect of expression of individual African swine fever genes, we summarise how the different steps in virus replication interact with the host cell and the current state of knowledge on how it modulates the resulting stress responses.

Modulating glycosphingolipid metabolism and autophagy improves outcomes in pre-clinical models of myeloma bone disease

Patients with multiple myeloma, an incurable malignancy of plasma cells, frequently develop osteolytic bone lesions that severely impact quality of life and clinical outcomes. Eliglustat, a U.S. Food and Drug Administration-approved glucosylceramide synthase inhibitor, reduced osteoclast-driven bone loss in preclinical in vivo models of myeloma. In combination with zoledronic acid, a bisphosphonate that treats myeloma bone disease, eliglustat provided further protection from bone loss. Autophagic degradation of TRAF3, a key step for osteoclast differentiation, was inhibited by eliglustat as evidenced by TRAF3 lysosomal and cytoplasmic accumulation. Eliglustat blocked autophagy by altering glycosphingolipid composition whilst restoration of missing glycosphingolipids rescued autophagy markers and TRAF3 degradation thus restoring osteoclastogenesis in bone marrow cells from myeloma patients. This work delineates both the mechanism by which glucosylceramide synthase inhibition prevents autophagic degradation of TRAF3 to reduce osteoclastogenesis as well as highlighting the clinical translational potential of eliglustat for the treatment of myeloma bone disease.