Activation and regulation mechanisms of NOD-like receptors based on structural biology

Inflammation unleashed: The role of pyroptosis in chronic liver diseases

Pyroptosis, a newly identified form of programmed cell death intertwined with inflammatory responses, is facilitated by the Gasdermin family's pore-forming activity, leading to cell lysis and the release of pro-inflammatory cytokines. This process is a double-edged sword in innate immunity, offering protection against pathogens while risking excessive inflammation and tissue damage when dysregulated. Specifically, pyroptosis operates through two distinct signaling pathways, namely the Caspase-1 pathway and the Caspase-4/5/11 pathway. In the context of chronic liver diseases like fibrosis and cirrhosis, inflammation emerges as a central contributing factor to their pathogenesis. The identification of inflammation is characterized by the activation of innate immune cells and the secretion of pro-inflammatory cytokines such as IL-1α, IL-1β, and TNF-α. This review explores the interrelationship between pyroptosis and the inflammasome, a protein complex located in liver cells that recognizes danger signals and initiates Caspase-1 activation, resulting in the secretion of IL-1β and IL-18. The article delves into the influence of the inflammasome and pyroptosis on various liver disorders, with a specific focus on their molecular and pathophysiological mechanisms. Additionally, the potential therapeutic implications of targeting pyroptosis for liver diseases are highlighted for future consideration.

Mannose and Lactobionic Acid in Nasal Vaccination: Enhancing Antigen Delivery via C-Type Lectin Receptors

BACKGROUND/OBJECTIVES

Nasal vaccines are a promising strategy for enhancing mucosal immune responses and preventing diseases at mucosal sites by stimulating the secretion of secretory IgA, which is crucial for early pathogen neutralization. However, designing effective nasal vaccines is challenging due to the complex immunological mechanisms in the nasal mucosa, which must balance protection and tolerance against constant exposure to inhaled pathogens. The nasal route also presents unique formulation and delivery hurdles, such as the mucous layer hindering antigen penetration and immune cell access.

METHODS

This review focuses on cutting-edge approaches to enhance nasal vaccine delivery, particularly those targeting C-type lectin receptors (CLRs) like the mannose receptor and macrophage galactose-type lectin (MGL) receptor. It elucidates the roles of these receptors in antigen recognition and uptake by antigen-presenting cells (APCs), providing insights into optimizing vaccine delivery.

RESULTS

While a comprehensive examination of targeted glycoconjugate vaccine development is outside the scope of this study, we provide key examples of glycan-based ligands, such as lactobionic acid and mannose, which can selectively target CLRs in the nasal mucosa.

CONCLUSIONS

With the rise of new viral infections, this review aims to facilitate the design of innovative vaccines and equip researchers, clinicians, and vaccine developers with the knowledge to enhance immune defenses against respiratory pathogens, ultimately protecting public health.

Unraveling the NLRP family: Structure, function, activation, critical influence on tumor progression, and potential as targets for cancer therapy

The innate immune system serves as the body's initial defense, swiftly detecting danger via pattern recognition receptors (PRRs). Among these, nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing proteins (NLRPs) are pivotal in recognizing pathogen-associated and damage-associated molecular patterns, thereby triggering immune responses. NLRPs, the most extensively studied subset within the NLR family, form inflammasomes that regulate inflammation, essential for innate immunity activation. Recent research highlights NLRPs' significant impact on various human diseases, including cancer. With differential expression across organs, NLRPs influence cancer progression by modulating immune reactions, cell fate, and proliferation. Their clinical significance in cancer makes them promising therapeutic targets. This review provides a comprehensive overview of the structure, function, activation mechanism of the NLRPs family and its potential role in cancer progression. In addition, we particularly focused on the concept of NLRP as a therapeutic target and its potential value in combination with immune checkpoint inhibitors.

Understanding the impact of in vitro transcription byproducts and contaminants

The success of messenger (m)RNA-based vaccines against SARS-CoV-2 during the COVID-19 pandemic has led to rapid growth and innovation in the field of mRNA-based therapeutics. However, mRNA production, whether in small amounts for research or large-scale GMP-grade for biopharmaceutics, is still based on the In Vitro Transcription (IVT) reaction developed in the early 1980s. The IVT reaction exploits phage RNA polymerase to catalyze the formation of an engineered mRNA that depends on a linearized DNA template, nucleotide building blocks, as well as pH, temperature, and reaction time. But depending on the IVT conditions and subsequent purification steps, diverse byproducts such as dsRNA, abortive RNAs and RNA:DNA hybrids might form. Unwanted byproducts, if not removed, could be formulated together with the full-length mRNA and cause an immune response in cells by activating host pattern recognition receptors. In this review, we summarize the potential types of IVT byproducts, their known biological activity, and how they can impact the efficacy and safety of mRNA therapeutics. In addition, we briefly overview non-nucleotide-based contaminants such as RNases, endotoxin and metal ions that, when present in the IVT reaction, can also influence the activity of mRNA-based drugs. We further discuss current approaches aimed at adjusting the IVT reaction conditions or improving mRNA purification to achieve optimal performance for medical applications.

Tissue-resident bacteria in metabolic diseases: emerging evidence and challenges

Although the impact of the gut microbiome on health and disease is well established, there is controversy regarding the presence of microorganisms such as bacteria and their products in organs and tissues. However, recent contamination-aware findings of tissue-resident microbial signatures provide accumulating evidence in support of bacterial translocation in cardiometabolic disease. The latter provides a distinct paradigm for the link between microbial colonizers of mucosal surfaces and host metabolism. In this Perspective, we re-evaluate the concept of tissue-resident bacteria including their role in metabolic low-grade tissue and systemic inflammation. We examine the limitations and challenges associated with studying low bacterial biomass samples and propose experimental and analytical strategies to overcome these issues. Our Perspective aims to encourage further investigation of the mechanisms linking tissue-resident bacteria to host metabolism and their potentially actionable health implications for prevention and treatment.

Role and molecular mechanism of NOD2 in chronic non-communicable diseases

Nucleotide-binding oligomerization domain containing 2 (NOD2), located in the cell cytoplasm, is a pattern recognition receptor belonging to the innate immune receptor family. It mediates the innate immune response by identifying conserved sequences in bacterial peptide glycans and plays an essential role in maintaining immune system homeostasis. Gene mutations of NOD2 lead to the development of autoimmune diseases such as Crohn's disease and Blau syndrome. Recently, NOD2 has been shown to be associated with the pathogenesis of diabetes, cardiac-cerebral diseases, and cancers. However, the function of NOD2 in these non-communicable diseases (CNCDs) is not well summarized in reviews. Our report mainly discusses the primary function and molecular mechanism of NOD2 as well as its potential clinical significance in CNCDs.

Immunotherapy in the context of sepsis-induced immunological dysregulation

Sepsis is a clinical syndrome caused by uncontrollable immune dysregulation triggered by pathogen infection, characterized by high incidence, mortality rates, and disease burden. Current treatments primarily focus on symptomatic relief, lacking specific therapeutic interventions. The core mechanism of sepsis is believed to be an imbalance in the host's immune response, characterized by early excessive inflammation followed by late immune suppression, triggered by pathogen invasion. This suggests that we can develop immunotherapeutic treatment strategies by targeting and modulating the components and immunological functions of the host's innate and adaptive immune systems. Therefore, this paper reviews the mechanisms of immune dysregulation in sepsis and, based on this foundation, discusses the current state of immunotherapy applications in sepsis animal models and clinical trials.

Unveiling the pathophysiology of restless legs syndrome through transcriptome analysis

The aim of this study was to analyze signaling pathways associated with differentially expressed messenger RNAs in people with restless legs syndrome (RLS). Seventeen RLS patients and 18 controls were enrolled. Coding RNA expression profiling of 12,857 gene transcripts by next-generation sequencing was performed. Enrichment analysis by pathfindR tool was carried-out, with p-adjusted ≤0.001 and fold-change ≥2.5. Nine main different network groups were significantly dysregulated in RLS: infections, inflammation, immunology, neurodegeneration, cancer, neurotransmission and biological, blood and metabolic mechanisms. Genetic predisposition plays a key role in RLS and evidence indicates its inflammatory nature; the high involvement of mainly neurotropic viruses and the TORCH complex might trigger inflammatory/immune reactions in genetically predisposed subjects and activate a series of biological pathways-especially IL-17, receptor potential channels, nuclear factor kappa-light-chain-enhancer of activated B cells, NOD-like receptor, mitogen-activated protein kinase, p53, mitophagy, and ferroptosis-involved in neurotransmitter mechanisms, synaptic plasticity, axon guidance, neurodegeneration, carcinogenesis, and metabolism.

The interaction of inflammasomes and gut microbiota: novel therapeutic insights

Inflammasomes are complex platforms for the cleavage and release of inactivated IL-1β and IL-18 cytokines that trigger inflammatory responses against damage-associated molecular patterns (DAMPs) or pathogen-associated molecular patterns (PAMPs). Gut microbiota plays a pivotal role in maintaining gut homeostasis. Inflammasome activation needs to be tightly regulated to limit aberrant activation and bystander damage to the host cells. Several types of inflammasomes, including Node-like receptor protein family (e.g., NLRP1, NLRP3, NLRP6, NLRP12, NLRC4), PYHIN family, and pyrin inflammasomes, interact with gut microbiota to maintain gut homeostasis. This review discusses the current understanding of how inflammasomes and microbiota interact, and how this interaction impacts human health. Additionally, we introduce novel biologics and antagonists, such as inhibitors of IL-1β and inflammasomes, as therapeutic strategies for treating gastrointestinal disorders when inflammasomes are dysregulated or the composition of gut microbiota changes.

Regulation of the AGEs-induced inflammatory response in human periodontal ligament cells via the AMPK/NF-κB/ NLRP3 signaling pathway

The heightened prevalence and accelerated progression of periodontitis in individuals with diabetes is primarily attributed to inflammatory responses in human periodontal ligament cells (HPDLCs). This study is aimed at delineating the regulatory mechanism of nucleotide-binding oligomerization domain-like receptors (NLRs) in mediating inflammation incited by muramyl dipeptide (MDP) in HPDLCs, under the influence of advanced glycation end products (AGEs), metabolic by-products associated with diabetes. We performed RNA-seq in HPDLCs induced by AGEs treatment and delineated activation markers for the receptor of AGEs (RAGE). It showed that advanced glycation end products modulate inflammatory responses in HPDLCs by activating NLRP1 and NLRP3 inflammasomes, which are further regulated through the NF-κB signaling pathway. Furthermore, AGEs synergize with NOD2, NLRP1, and NLRP3 inflammasomes to augment MDP-induced inflammation significantly.

DNA methylation profiling reveals potential biomarkers of β-lactams induced fatal anaphylactic shock

Anaphylaxis is a serious reaction of systemic hypersensitivity with that rapid onset and sudden death. Drug hypersensitivity, particularly induced by β-lactams, is one of the most frequent causes of anaphylaxis in adults. But identification of anaphylactic shock, in forensic sciences recently, is difficult, because it mainly depends on nonspecific characteristic morphological changes, as well as exclusion and circumstantial evidence. Here, we detected DNA methylation signatures of β-lactams-induced fatal anaphylactic shock with the Illumina Infinium Human Methylation EPIC BeadChip, to screen potential forensic biomarkers and reveal the molecular mechanisms of drug-induced anaphylaxis with fatal shock and sudden death. Our results indicated that DNA methylation was associated with β-lactams-induced fatal anaphylactic shock, in which the hypomethylation played a vital role. We found that 1459 differentially methylated positions (DMPs) were mainly involved in β-lactams-induced fatal anaphylactic shock by regulating MAPK and other signaling pathways. 18 DNA methylation signatures that could separate β-lactams-induced anaphylactic shock from healthy individuals were identified. The altered methylation of DMPs can affect the transcription of corresponding genes and promote β-lactams-induced fatal anaphylactic shock. The results suggest that DNA methylation can detect forensic identification markers of drug-induced anaphylaxis with fatal shock and sudden death, and it is an effective method for the forensic diagnosis.

NLRP6 deficiency inhibits neuroinflammation and ameliorates brain injury in ischemic stroke by blocking NLRs inflammasomes activation through proteasomal degradation of pro-caspase-1

Innate inflammation is crucial for ischemic stroke development. NLRP6, a nucleotide-binding and oligomerization domain-like receptors (NLRs) family member, regulates innate inflammation. Whether NLRP6 regulates neurological damage and neuroinflammation during ischemic stroke remains unclear. We report that NLRP6 is abundantly expressed in microglia and significantly upregulated in the ischemic brain. The brain injury severity was alleviated in NLRP6-deficient mice after ischemic stroke, as evidenced by reduced cerebral infarct volume, decreased neurological deficit scores, improved histopathological morphological changes, ameliorated neuronal denaturation, and relief of sensorimotor dysfunction. In the co-culture OGD/R model, NLRP6 deficiency prevented neuronal death and attenuated microglial cell injury. NLRP6 deficiency blocked several NLRs inflammasomes' activation and abrogated inflammasome-related cytokine production by decreasing the expression of the common effector pro-caspase-1. NLRP6 deficiency reduced pro-caspase-1's protein level by inducing proteasomal degradation. These findings confirm the neuroprotective role of NLRP6 deficiency in ischemic stroke and its underlying regulation mechanism in neuroinflammation and provide a potential therapeutic target for ischemic stroke.

Enterovirus D68 3C protease antagonizes type I interferon signaling by cleaving signal transducer and activator of transcription 1

Following the successful control of poliovirus, the re-emergence of respiratory enterovirus D68 (EV-D68), a prominent non-polio enterovirus, has become a serious public health concern worldwide. Host innate immune responses are the primary defense against EV-D68 invasion; however, the mechanism underlying viral evasion of the antiviral activity of interferons (IFN) remains unclear. In this study, we found that EV-D68 inhibited type I IFN signaling by cleaving signal transducer and activator of transcription 1 (STAT1), a crucial factor in cellular responses to interferons and other cytokines. We observed that the prototype and circulating EV-D68 strains conserved their ability to induce STAT1 cleavage and attenuate IFN signal transduction. Further investigation revealed that EV-D68 3C protease cleaves STAT1 at the 131Q residue. Interestingly, not all enterovirus-encoded 3C proteases exhibited this ability. EV-D68 and poliovirus 3C proteases efficiently induced STAT1 cleavage; whereas, 3C proteases from EV-A71, coxsackievirus A16, and echoviruses did not. STAT1 cleavage also abolished the nuclear translocation capacity of STAT1 in response to IFN stimulation to activate downstream signaling elements. Overall, these results suggest that STAT1, targeted by viral protease 3C, is utilized by EV-D68 to subvert the host's innate immune response.IMPORTANCEEnterovirus D68 (EV-D68) has significantly transformed over the past decade, evolving from a rare pathogen to a potential pandemic pathogen. The interferon (IFN) signaling pathway is an important defense mechanism and therapeutic target for the host to resist viral invasion. Previous studies have reported that the EV-D68 virus blocks or weakens immune recognition and IFN production in host cells through diverse strategies; however, the mechanisms of EV-D68 resistance to IFN signaling have not been fully elucidated. Our study revealed that EV-D68 relies on its own encoded protease, 3C, to directly cleave signal transducer and activator of transcription 1 (STAT1), a pivotal transduction component in the IFN signaling pathway, disrupting the IFN-mediated antiviral response. Previous studies on human enteroviruses have not documented direct cleavage of the STAT1 protein to evade cellular immune defenses. However, not all enteroviral 3C proteins can cleave STAT1. These findings highlight the diverse evolutionary strategies different human enteroviruses employ to evade host immunity.

A mouse model to distinguish NLRP6-mediated inflammasome-dependent and -independent functions

The NOD-like receptor (NLR) family pyrin domain containing 6 (NLRP6) serves as a sensor for microbial dsRNA or lipoteichoic acid (LTA) in intestinal epithelial cells (IECs), and initiating multiple pathways including inflammasome pathway and type I interferon (IFN) pathway, or regulating nuclear factor-κB (NF-κB) and mitogen-activated protein kinase (MAPK) pathways. NLRP6 can exert its function in both inflammasome-dependent and inflammasome-independent manners. However, there is no tool to distinguish the contribution of individual NLRP6-mediated pathway to the physiology and pathology in vivo. Here, we validated that Arg39 and Trp50 residues in the pyrin domain (PYD) of murine NLRP6 are required for ASC recruitment and inflammasome activation, but are not important for the RNA binding and PYD-independent NLRP6 oligomerization. We further generated the Nlrp6R39E&W50E mutant mice, which showed reduced inflammasome activation in either steady state intestine or during viral infection. However, the type I IFN production in cells or intestine tissue from Nlrp6R39E&W50E mutant mice remain normal. Interestingly, NLRP6-mediated inflammasome activation or the IFN-I production seems to play distinct roles in the defense responses against different types of RNA viruses. Our work generated a useful tool to study the inflammasome-dependent role of NLRP6 in vivo, which might help to understand the complexity of multiple pathways mediated by NLRP6 in response to the complicated and dynamic environmental cues in the intestine.

Linking NLRP3 inflammasome and pulmonary fibrosis: mechanistic insights and promising therapeutic avenues

Pulmonary fibrosis is a devastating disorder distinguished by redundant inflammation and matrix accumulation in the lung interstitium. The early inflammatory cascade coupled with recurring tissue injury orchestrates a set of events marked by perturbed matrix hemostasis, deposition of matrix proteins, and remodeling in lung tissue. Numerous investigations have corroborated a direct correlation between the NLR family pyrin domain-containing 3 (NLRP3) activation and the development of pulmonary fibrosis. Dysregulated activation of NLRP3 within the pulmonary microenvironment exacerbates inflammation and may incite fibrogenic responses. Nevertheless, the precise mechanisms through which the NLRP3 inflammasome elicits pro-fibrogenic responses remain inadequately defined. Contemporary findings suggest that the pro-fibrotic consequences stemming from NLRP3 signaling primarily hinge on the action of interleukin-1β (IL-1β). IL-1β instigates IL-1 receptor signaling, potentiating the activity of transforming growth factor-beta (TGF-β). This signaling cascade, in turn, exerts influence over various transcription factors, including SNAIL, TWIST, and zinc finger E-box-binding homeobox 1 (ZEB 1/2), which collectively foster myofibroblast activation and consequent lung fibrosis. Here, we have connected the dots to illustrate how the NLRP3 inflammasome orchestrates a multitude of signaling events, including the activation of transcription factors that facilitate myofibroblast activation and subsequent lung remodeling. In addition, we have highlighted the prominent role played by various cells in the formation of myofibroblasts, the primary culprit in lung fibrosis. We also provided a concise overview of various compounds that hold the potential to impede NLRP3 inflammasome signaling, thus offering a promising avenue for the treatment of pulmonary fibrosis.

Differential Gene Expression and Immune Cell Infiltration in Patients with Steroid-induced Necrosis of the Femoral Head

OBJECTIVE

The study aimed to study the differential gene expression and immune cell infiltration in patients with steroid-induced necrosis of the femoral head (SANFH), identify the key genes and immune cells of SANFH, and explore the relationship between immune cells and SANFH.

METHODS

The high-throughput gene chip dataset GSE123568 was downloaded from the GEO database, and the differential gene expression was analyzed with the R language. The STRING database and Cytoscape software were used to analyze the protein interaction network and screen key genes, and enrichment analysis was carried out on key genes. The infiltration of immune cells in SANFH patients was analyzed and verified by immunohistochemistry.

RESULTS

EP300, TRAF6, STAT1, JAK1, CASP8, and JAK2 are key genes in the pathogenesis of SANFH, which mainly involve myeloid cell differentiation, cytokine-mediated signaling pathway, tumor necrosis factor-mediated signaling pathway, and cellular response to tumor necrosis factor through JAK-STAT, NOD-like receptor, toll-like receptor, and other signaling pathways, leading to the occurrence of diseases; immune infiltration and immunohistochemical results have shown the expression of memory B cells and activated dendritic cells as reduced in SANFH patients, while in the same SANFH samples, M1 macrophages have been positively correlated with monocytes, and neutrophils have been negatively correlated with monocytes expression.

CONCLUSION

EP300, TRAF6, STAT1, JAK1, CASP8, and JAK2 have exhibited significant differences in SANFH (spontaneous osteonecrosis of the femoral head). Memory B cells, activated dendritic cells, M1 macrophages, monocytes, and neutrophils have shown abnormal expression in SANFH.

Pyroptosis in neurodegenerative diseases: from bench to bedside

The central nervous system regulates all aspects of physiology to some extent. Neurodegenerative diseases (NDDs) lead to the progressive loss and dysfunction of neurons, which are particularly evident in Alzheimer's disease, Parkinson's disease, and many other conditions. NDDs are multifactorial diseases with complex pathogeneses, and there has been a rapid increase in the prevalence of NDDs. However, none of these diseases can be cured, making the development of novel treatment strategies an urgent necessity. Numerous studies have indicated how pyroptosis induces inflammation and affects many aspects of NDD. Therefore, components related to pyroptosis are potential therapeutic candidates and are attracting increasing attention. Here, we review the role of pyroptosis in the pathogenesis of NDDs and potential treatment options. Additionally, several of the current drugs and relevant inhibitors are discussed. Through this article, we provide theoretical support for exploring new therapeutic targets and updating clinical treatment strategies for NDDs. Notably, pyroptosis, a recently widely studied mode of cell death, is still under-researched compared to other traditional forms of cell death. Moreover, the focus of research has been on the onset and progression of NDDs, and the lack of organ-specific target discovery and drug development is a common problem for many basic studies. This urgent problem requires scientists and companies worldwide to collaborate in order to develop more effective drugs against NDDs.

The pseudokinase MLKL contributes to host defense against Streptococcus pluranimalium infection by mediating NLRP3 inflammasome activation and extracellular trap formation

Host innate immunity plays a pivotal role in the early detection and neutralization of invading pathogens. Here, we show that pseudokinase mixed lineage kinase-like protein (MLKL) is required for host defence against Streptococcus pluranimalium infection by enhancing NLRP3 inflammasome activation and extracellular trap formation. Notably, Mlkl deficiency leads to increased mortality, increased bacterial colonization, severe destruction of organ architecture, and elevated inflammatory cell infiltration in murine models of S. pluranimalium pulmonary and systemic infection. In vivo and in vitro data provided evidence that potassium efflux-dependent NLRP3 inflammasome signalling downstream of active MLKL confers host protection against S. pluranimalium infection and initiates bacterial killing and clearance. Moreover, Mlkl deficiency results in defects in extracellular trap-mediated bactericidal activity. In summary, this study revealed that MLKL mediates the host defence response to S. pluranimalium, and suggests that MLKL is a potential drug target for preventing and controlling pathogen infection.

Sarcoid Uveitis in Children

Sarcoidosis is a multi-system granulomatous disease that often presents with uveitis. Although sarcoidosis and sarcoid uveitis typically occur in adulthood, children also may be affected. There are two distinct clinical presentations of the pediatric disease, associated with younger and older age groups, and having different causations. "Early-onset sarcoidosis", beginning at age 5 years or less, is an autosomal dominant genetic disease, caused by a mutation in the NOD2 gene. It is also known as sporadic Blau syndrome or Jabs syndrome. "Adult-type sarcoidosis", usually beginning between the ages of 8 and 15 years, is believed to represent an excessive response to an environmental antigen. There is limited literature on the management of pediatric sarcoidosis, and treatment follows an approach applied to other forms of pediatric non-infectious uveitis. When systemic immunomodulatory therapy is indicated, methotrexate and/or adalimumab are often employed. The condition may persist into adulthood, and thus long-term follow-up is indicated.

Risk factors, clinical features and treatment of Behçet's disease uveitis

Behçet's disease is a systemic vasculitis frequently associated with intraocular inflammation. Recent findings identified independent clinical clusters in Behçet's disease, each involving distinct combinations of affected organs. Ocular Behçet's disease, mainly manifested as uveitis, is characterized as an independent cluster with a low likelihood of association with other system involvements, such as intestinal, cardiovascular, or central nervous system. A prevailing theory suggests that the pathogenesis of the disease is multifactorial, where a variety of genetic and infectious agents may interact with each other to cause the disease. Among sporadic cases, the human leukocyte antigen (HLA) genes, including HLA-B51, HLA-A26, HLA-B15, and HLA-B5701, have been found to be a key component conferring genetic susceptibility. Outside the HLA region, a set of susceptibility variants are identified, closely related to interleukin (IL)-23/IL-17 pathway, tumor necrosis factor (TNF) signaling, and pattern recognition receptor systems. Microbial infections, such as Streptococcus sanguinis, Mycobacterium tuberculosis, and Herpes simplex virus (HSV), are linked to play the triggering of disease in immunogenetically predisposed individuals. Clinically, due to the notable relapsing-remitting course of ocular Behçet's disease, the prevention of recurrent attack would be the primary treatment goal. Combination of corticosteroids and immunomodulatory drugs, such as anti-TNF agents, interferon, and conventional immunosuppressants (e.g. cyclosporine, azathioprine), have been the mainstream regimen for the disease. Future research may focus on comparing the effectiveness of immunomodulatory drugs and identifying the most suitable subgroups for a specific drug on the basis of the knowledge of the molecular heterogeneity of the disease.

The neuropathological mechanism of EV-A71 infection attributes to inflammatory pryoptosis and viral replication via activating the hsa_circ_0045431/ hsa_miR_584/NLRP3 regulatory axis

Neuropathological damage has been considered to be the main cause of death from EV-A71 infection, but the underlying mechanism has not been elucidated. Pyroptosis, a new form of inflammatory programmed cell death, has been verified to be involved in the pathogenesis of various viruses. circRNAs are a novel type of endogenous noncoding RNA gaining research interest in recent years, especially their special roles in the process of virus infection. Thus, in this study, we combined EV-A71, pyroptosis and circRNA to find a breakthrough in the pathogenesis of EV-A71 infection. Firstly, whether EV-A71 infection leaded to pyroptosis formation was examined by a series detection of cell death, cell viability, LDH release, caspase 1 activity, the expression levels of pyroptosis-related molecules and the concentrations of IL-1β and IL-18. Secondly, high-throughput sequencing of circRNAs was carried out to excavate the circRNA-miRNA-mRNA regulatory axis which might be associated with pyroptosis formation. Finally, the gain- and loss-of-functional experiments were further conducted to identify their functions. Our results showed that EV-A71 infection caused pyroptosis formation in SH-SY5Y cells. The circRNA sequencing analyzed the differentially expressed circRNAs and their possible functions. It was found that the hsa_circ_0045431/hsa_miR_584/NLRP3 regulatory axis might be involved in pyroptosis formation during EV-A71 infection. Then, hsa_circ_0045431 sponged hsa_miR_584 and hsa_miR_584 directly targeted NLRP3 were validated by IF, dual-luciferase, qRT-PCR and WB assays. Functional experiments were performed to further uncover that the up-regulation of hsa_circ_0045431 and NLRP3 promoted the inflammatory pyroptosis and viral replication, while the up-regulation of hsa_miR_584 suppressed the inflammatory pyroptosis and viral replication, and vice versa. Collectively, our study demystified that EV-A71 infection induced pyroptosis formation by activating hsa_circ_0045431/hsa_miR_584/NLRP3 regulatory axis, which could further effect viral replication. These findings provided novel insights into the pathogenesis of EV-A71 infection, and meanwhile revealed that the hsa_circ_0045431/ hsa_miR_584/NLRP3 regulatory axis can serve as a potential biological therapeutic target for EV-A71 infection.

MDA5 with Complete CARD2 Region Inhibits the Early Replication of H9N2 AIV and Enhances the Immune Response during Vaccination

Chicken melanoma differentiation-associated gene 5 (MDA5) is a member of the RLRs family that recognizes the viral RNAs invading cells and activates downstream interferon regulatory pathways, thereby inhibiting viral replication. The caspase activation and recruitment domain (CARD) is the most important region in MDA5 protein. However, the antiviral and immune enhancement of MDA5 with the CARD region remains unclear. In this study, two truncated MDA5 genes with different CARD regions, namely MDA5-1 with CARD1 plus partial CARD2 domain and MDA5-2 with CARD1 plus complete CARD2 domain, were cloned via reverse transcription PCR and ligated into plasmid Flag-N vector to be Flag-MDA5-1 and Flag-MDA5-2 plasmids. DF-1 cells were transfected with two plasmids for 24 h and then inoculated with H9N2 virus (0.1 MOI) for 6 h to detect the levels of IFN-β, PKR, MAVS, and viral HA, NA, and NS proteins expression. The results showed that MDA5-1 and MDA5-2 increased the expression of IFN-β and PKR, activated the downstream molecule MAVS production, and inhibited the expression of HA, NA, and NS proteins. The knockdown of MDA5 genes confirmed that MDA5-2 had a stronger antiviral effect than that of MDA5-1. Furthermore, the recombinant proteins MDA5-1 and MDA5-2 were combined with H9N2 inactivated vaccine to immunize SPF chickens subcutaneously injected in the neck three times. The immune response of the immunized chicken was investigated. It was observed that the antibody titers and expressions of immune-related molecules from the chicken immunized with MDA5-1 and MDA5-2 group were increased, in which the inducing function of MDA5-2 groups was the highest among all immunization groups. These results suggested that the truncated MDA5 recombinant proteins with complete CARD2 region could play vital roles in antiviral and immune enhancement. This study provides important material for the further study of the immunoregulatory function and clinical applications of MDA5 protein.

The NLRP11 Protein Bridges the Histone Lysine Acetyltransferase KAT7 to Acetylate Vimentin in the Early Stage of Lung Adenocarcinoma

Accumulation of vimentin is the core event in epithelial-mesenchymal transition (EMT). Post-translational modifications have been widely reported to play crucial roles in imparting different properties and functions to vimentin. Here, a novel modification of vimentin, acetylated at Lys104 (vimentin-K104Ac) is identified, which is stable in lung adenocarcinoma (LUAD) cells. Mechanistically, NACHT, LRR, and PYD domain-containing protein 11 (NLRP11), a regulator of the inflammatory response, bind to vimentin and promote vimentin-K104Ac expression, which is highly expressed in the early stages of LUAD and frequently appears in vimentin-positive LUAD tissues. In addition, it is observed that an acetyltransferase, lysine acetyltransferase 7 (KAT7), which binds to NLRP11 and vimentin, directly mediates the acetylation of vimentin at Lys104 and that the cytoplasmic localization of KAT7 can be induced by NLRP11. Malignant promotion mediated by transfection with vimentin-K104Q is noticeably greater than that mediated by transfection with vimentin-WT. Further, suppressing the effects of NLRP11 and KAT7 on vimentin noticeably inhibited the malignant behavior of vimentin-positive LUAD in vivo and in vitro. In summary, these findings have established a relationship between inflammation and EMT, which is reflected via KAT7-mediated acetylation of vimentin at Lys104 dependent on NLRP11.

Nlrp3 Deficiency Alleviates Lipopolysaccharide-Induced Acute Kidney Injury via Suppressing Renal Inflammation and Ferroptosis in Mice

The nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3) inflammasome is a vital component of many inflammatory responses. Here, we intended to investigate the involvement of NLRP3 in lipopolysaccharide (LPS)-induced sepsis-associated acute kidney injury (S-AKI) and explore its mechanisms. For the first time, we validated elevated NLRP3 expression in the renal tissues of S-AKI patients by immunohistochemistry analysis. Through LPS injection in both wild-type and Nlrp3-/- mice, a S-AKI model was developed. It was found that LPS-induced kidney injury, including an abnormal morphology in a histological examination, abnormal renal function in a laboratory examination, and an increase in the expression of AKI biomarkers, was dramatically reversed in Nlrp3-deficient mice. Nlrp3 deletion alleviated renal inflammation, as evidenced by the suppression of the expression of pro-inflammatory cytokines and chemokines. A combinative analysis of RNA sequencing and the FerrDb V2 database showed that Nlrp3 knockout regulated multiple metabolism pathways and ferroptosis in LPS-induced S-AKI. Further qPCR coupled with Prussian blue staining demonstrated that Nlrp3 knockout inhibited murine renal ferroptosis, indicating a novel mechanism involving S-AKI pathogenesis by NLRP3. Altogether, the aforementioned findings suggest that Nlrp3 deficiency alleviates LPS-induced S-AKI by reducing renal inflammation and ferroptosis. Our data highlight that NLRP3 is a potential therapeutic target for S-AKI.

The Characteristics of Tumor Microenvironment Predict Survival and Response to Immunotherapy in Adrenocortical Carcinomas

Increasing evidence confirms that tumor microenvironment (TME) can influence tumor progression and treatment, but TME is still understudied in adrenocortical carcinoma (ACC). In this study, we first scored TME using the xCell algorithm, then defined genes associated with TME, and then used consensus unsupervised clustering analysis to construct TME-related subtypes. Meanwhile, weighted gene co-expression network analysis was used to identify modules correlated with TME-related subtypes. Ultimately, the LASSO-Cox approach was used to establish a TME-related signature. The results showed that TME-related scores in ACC may not correlate with clinical features but do promote a better overall survival. Patients were classified into two TME-related subtypes. Subtype 2 had more immune signaling features, higher expression of immune checkpoints and MHC molecules, no CTNNB1 mutations, higher infiltration of macrophages and endothelial cells, lower tumor immune dysfunction and exclusion scores, and higher immunophenoscore, suggesting that subtype 2 may be more sensitive to immunotherapy. 231 modular genes highly relevant to TME-related subtypes were identified, and a 7-gene TME-related signature that independently predicted patient prognosis was established. Our study revealed an integrated role of TME in ACC and helped to identify those patients who really responded to immunotherapy, while providing new strategies on risk management and prognosis prediction.

Structure, biochemical function, and signaling mechanism of plant NLRs

To counter pathogen invasion, plants have evolved a large number of immune receptors, including membrane-resident pattern recognition receptors (PRRs) and intracellular nucleotide-binding and leucine-rich repeat receptors (NLRs). Our knowledge about PRR and NLR signaling mechanisms has expanded significantly over the past few years. Plant NLRs form multi-protein complexes called resistosomes in response to pathogen effectors, and the signaling mediated by NLR resistosomes converges on Ca²⁺-permeable channels. Ca²⁺-permeable channels important for PRR signaling have also been identified. These findings highlight a crucial role of Ca²⁺ in triggering plant immune signaling. In this review, we first discuss the structural and biochemical mechanisms of non-canonical NLR Ca²⁺ channels and then summarize our knowledge about immune-related Ca²⁺-permeable channels and their roles in PRR and NLR signaling. We also discuss the potential role of Ca²⁺ in the intricate interaction between PRR and NLR signaling.

Proportion of Concentrate in the Diet of Early Lactation Dairy Cows Has Contrasting Effects on Circulating Leukocyte Global Transcriptomic Profiles, Health and Fertility According to Parity

The functionality of circulating leukocytes in dairy cows is suppressed after calving, with negative energy balance as a risk factor. Leukocyte transcriptomic profiles were compared separately in 44 multiparous (MP) and 18 primiparous (PP) Holstein-Friesian cows receiving diets differing in concentrate proportion to test whether immune dysfunction could be mitigated by appropriate nutrition. After calving, cows were offered either (1) low concentrate (LC); (2) medium concentrate (MC) or (3) high concentrate (HC) diets with proportions of concentrate to grass silage of 30%:70%, 50%:50% and 70%:30%, respectively. Cow phenotype data collected included circulating metabolites, milk yield and health and fertility records. RNA sequencing of circulating leukocytes at 14 days in milk was performed. The HC diet improved energy balance in both age groups. There were more differentially expressed genes in PP than MP cows (460 vs. 173, HC vs. LC comparison) with few overlaps. The MP cows on the LC diet showed upregulation of the complement and coagulation cascade and innate immune defence mechanisms against pathogens and had a trend of more cases of mastitis and poorer fertility. In contrast, the PP cows on the HC diet showed greater immune responses based on both gene expression and phenotypic data and longer interval of calving to conception. The leukocytes of MP and PP cows therefore responded differentially to the diets between age, nutrient supply and immunity affecting their health and subsequent fertility.