This narrative review discusses mechanisms underlying bidirectional communication between sleep and the immune system with a focus on innate immune signaling and neuroinflammatory processes. Decades of mechanistic research demonstrate that sleep and immune function are tightly integrated across molecular, cellular, and systems levels. Seminal experiments from the late 1960 s through the early 1980 s established that microbial products, such as muramyl peptides and lipopolysaccharide, along with cytokines including IL-1 and TNF, alter sleep and participate in its physiological regulation. These findings launched contemporary investigations into how innate immune receptors, PAMP recognition, and downstream inflammatory signaling shape sleep-wake architecture. More recent work demonstrates that acute or chronic sleep disruption-including deprivation, restriction, and fragmentation-activates inflammatory signaling pathways, alters cytokine expression, and induces neuroinflammatory responses within the brain. At the cellular level, glial cells play central roles in mediating these effects and linking immune activation to neuronal circuits regulating sleep-wake behavior. Together, these advances reveal that sleep-immune interactions are deeply integrated and critical for maintaining health.
Human adenovirus (HAdV), a double-stranded DNA virus, targets terminally differentiated cells in the upper respiratory tract. As a key platform for gene therapy vectors, elucidating HAdV's virulence factors is vital for optimizing therapeutic applications and mitigating risks. To achieve productive replication, HAdV strategically neutralizes host immune defenses and induces S-phase pathways essential for viral propagation. This review synthesizes the latest insights into the key pathways through which HAdVs harness these early proteins to enhance virulence, skilfully evading and counteracting host defense mechanisms while propelling viral replication. As foundational platforms for gene therapy vectors (e.g., in oncology and rare disease treatments) and vaccine backbones (e.g., COVID-19 vaccines like ChAdOx1), understanding HAdV's immunoshadowing-the multifaceted strategies used to cloak innate and adaptive immunity-is crucial for enhancing vector safety and efficacy. Recent insights unveil how early viral proteins-including E1A, E1B-55K, E4orf1, E4orf3, E4orf6, and the E3 complex-participate in these processes. This review critically synthesizes these pathways, evaluating study limitations such as reliance on immortalized cell lines that underestimate the role of these proteins in immunological competent cells, and addresses unresolved controversies, including differential immunoshadowing efficacy across HAdV species that impacts vaccine design.
African swine fever (ASF) is a highly contagious and lethal disease caused by African swine fever virus (ASFV), with a mortality rate approaching up to 100%. At present, the functions of multiple genes of ASFV remain to be elucidated. In this study, we demonstrate that pD345L is a late-expressed viral protein and localizes to the viral factory. The recombinant strain JX23-02ΔD345L was obtained from the genotype Ⅰ/Ⅱ strain JX23-02. In vitro assays demonstrated that the deletion of D345L remarkably impairs viral replication. Further analyses revealed that JX23-02ΔD345L significantly upregulated pro-inflammatory cytokines (IL-1β, TNF-α) and IFN pathway components in PAMs, induced pyroptosis, apoptosis, and interferon responses. In vivo animal experiments demonstrated that the JX23-02ΔD345L strain was completely attenuated in pigs, failing to induce any typical clinical signs of ASF even with a high-dose inoculation. Moreover, a single immunization with JX23-02ΔD345L can elicit specific humoral and cellular immune responses against ASFV, conferring 80% protection against intramuscular challenge with the homologous strain JX23-02 and 60% protection against heterologous strain SY18. These results reveal D345L as a crucial virulence-related gene for ASFV pathogenesis, which is highly correlated with viral replication and the host antiviral response. Furthermore, JX23-02ΔD345L represented a candidate for the development of effective and safe ASFV vaccines. This finding provides a foundation for the research on ASFV and offers an important target and evidence for vaccine development.
Trained immunity refers to the enduring functional reprogramming of innate immune cells after particular stimuli, driven by epigenetic and metabolic alterations that augment non-specific responses upon subsequent exposure. Neutrophils and monocytes/macrophages, as essential innate effectors, are crucial for the induction and control of trained immunity, which is the primary emphasis of this review. Neutrophils, the predominant circulating leukocytes, were historically considered incapable of memory owing to their brief lifespan. Emerging evidence indicates that trained immunity functions at the bone marrow progenitor level, influencing granulopoiesis to produce neutrophils with lasting functional modifications. This research offers new insights into neutrophil functions in infection, cancer, and inflammation. Monocytes and macrophages, characterized by phenotypic plasticity and tissue residence, function as conventional models of trained immunity. They experience direct peripheral reprogramming or emerge as primed descendants of trained bone marrow precursors, performing pro-inflammatory or reparative roles in malignancies, infections, and ischemia lesions. This study comprehensively outlines the regulatory mechanisms of trained immunity in these cells, clarifies their functions in various clinical situations, and examines therapeutic applications. Comprehending these pathways is crucial for elucidating the cellular foundation of innate immunological memory, uncovering its multiple functions in disease, and guiding innovative therapeutics aimed at granulopoiesis and monocyte-macrophage polarization.
The osteoblast lineage has traditionally been viewed through a structural and metabolic lens, yet growing evidence indicates that these cells possess diverse functions, including roles in innate and adaptive immune responses. To establish a coherent mechanistic framework, we performed a systematic review of the literature concerning immune signalling, antigen presentation, and pathogen responses across the osteoblast lineage. We identified 463 unique studies, with 43 meeting the inclusion criteria. Our synthesis reveals a stage-specialised immune continuum. Osteoprogenitors appear to initiate early inflammatory signalling while mature osteoblasts operate as microbial sensors and conditional antigen-presenting cells via inducible expression of cell membrane and cytosolic pattern recognition receptors, and a functional major histocompatibility complex class II apparatus. Osteocytes, the most abundant and long-lived bone cell type, are also capable of detecting microbial danger and activate extensive interferon, chemokine and cytokine programmes within the lacunocanalicular network. Together, these properties define a stromal immune system that coordinates both innate and adaptive immunity across bone surfaces and the mineralised matrix. This osteoblast lineage-integrated immune architecture provides a conceptual basis for understanding osteomyelitis incidence and persistence, biomaterial-immune interactions, as well as inflammatory bone remodelling, reframing this lineage as a previously underappreciated regulator of skeletal and systemic immunity.
The ten-eleven translocation (TET) family genes, which encode 5-methylcytosine (5mC) dioxygenases, play a "double-edged sword" role in tumor initiation and progression. However, the functional role and molecular mechanism of tumor cell-intrinsic TET3 in anti-tumor immunity remain incompletely understood. Here, we uncover that TET3 mRNA expression was aberrantly elevated in multiple cancer types and correlated with poor overall survival. Transcriptomic analysis reveals that TET3 depletion upregulated the expression of innate immune response genes, including numerous interferon-stimulated genes (ISGs), in cancer cells. The expression levels of dsRNA sensors (i.e., MDA5 and RIG-I) were increased in TET3 KO or KD cells, while the biogenesis of endogenous dsRNA was not affected. Mechanistically, TET3 regulates type I interferon signaling by inhibiting STAT1 activation. Importantly, depletion of TET3 in B16F10 melanoma cells significantly curbed the synergistic tumor growth, accompanied by increased tumor-infiltrating CD4+ T cells, CD8+ T cells, and dendritic cells. Notably, analysis of the TCGA dataset also shows that TET3 expression levels were negatively correlated with tumor-infiltrating cytotoxic CD8+ T cells and MHC-I expression across multiple cancer types. Taken together, our findings identify TET3 as a new negative regulator of the type I interferon signaling in cancer cells. We envisage that targeting the tumor cell-intrinsic TET3 could reduce tumor immune evasion and promote anti-tumor immunity.
In addition to inducing pathogen-specific adaptive immune responses, vaccines can train the innate immune system, thereby providing broader host protection. This concept of trained immunity (TRIM) is well-established in benchtop laboratory science. This review aims to evaluate the current evidence of vaccine-induced TRIM and translate these findings into a clinical context. Various laboratory methods are used to assess TRIM; however, inconsistent results have been reported across non-BCG vaccine studies. Existing analyses lack exploration of the mechanistic basis of vaccine-induced TRIM, particularly epigenetic reprogramming and metabolic rewiring. Patterns emerge between vaccines: live-attenuated vaccines generally induce TRIM, as evidenced by increased inflammatory cytokine production upon restimulation, whereas non-live vaccines tend to demonstrate reduced trained immunity. Such findings are not consistently observed for mRNA vaccines, which show heterogeneous patterns. The limited variety of studies on non-BCG vaccines impacts the reliability of findings. A more comprehensive understanding of the mechanisms and outputs of TRIM induced by specific vaccines could better inform rational vaccine design. Furthermore, various modifiers can alter vaccine-induced TRIM responses, including sequence and route of administration, sex, and age. Consideration of these modifiers has important clinical implications in optimising vaccine administration for enhanced immune protection.
The E3 ubiquitin ligase Stub1 (CHIP) is a core regulator of protein homeostasis and antiviral innate immunity, with established roles in targeting RIG‑I and MAVS for proteasomal or autophagic degradation. Here, we summarize our recent work revealing that Stub1 negatively regulates type I interferon (IFN‑I) production by driving chaperone‑mediated autophagy (CMA)-dependent degradation of TBK1. Stub1 directly interacts with TBK1 and catalyzes K27‑linked polyubiquitination at lysine 344 (K344) of TBK1, which enables recognition by the CMA chaperone HSC70 via a conserved KFDKQ CMA recognition motif. Subsequently, ubiquitinated TBK1 is delivered to lysosomes via HSC70 and the lysosomal membrane protein LAMP2A for degradation. This process is independent of macroautophagy and the ubiquitin - proteasome system. Myeloid‑specific Stub1 knockout mice show enhanced IFN‑I responses, lower viral loads, and improved survival rates upon viral infection. This study defines a Stub1-CMA signaling axis that fine‑tunes antiviral immunity and expands the regulatory scope of ubiquitin codes in selective protein degradation pathways.
Heterogeneous nuclear ribonucleoproteins (hnRNPs) play important roles in the life cycle of influenza A virus (IAV). Our previous mass spectrometry analysis identified cellular hnRNP D as a novel interaction partner of the IAV polymerase basic 2 (PB2) protein. However, the functional implications of hnRNP D in IAV replication and the underlying mechanisms remained unknown. In this study, we confirmed that hnRNP D directly interacts with the PB2 protein of the A/Puerto Rico/8/1934 (PR8, H1N1) strain, while also binding to other proteins within viral ribonucleoprotein complexes (vRNPs). These interactions collectively inhibit vRNPs assembly and viral polymerase activity. However, we have found that hnRNP D enhances the viral titer of IAV in A549 cells. Mechanistically, hnRNP D suppresses the activation of the interferon (IFN)-β promoter, and the mRNA levels of downstream factors in the type I IFN signaling pathway. In detail, hnRNP D inhibits IFN-β promoter activation induced by crucial antiviral proteins and interacts strongly with the interferon regulatory factor 3 (IRF3). More importantly, hnRNP D blocks the binding of TANK-binding kinase 1 (TBK1) to IRF3, thereby impeding the phosphorylation and activation of IRF3. Collectively, we unveil a novel viral immune evasion strategy by which IAV hijacks a host RNA-binding protein, hnRNP D, to facilitate self-replication. This work not only elucidates the intricate trade-off mechanisms in virus-host interaction but also identifies hnRNP D as a potential therapeutic target aimed at bolstering antiviral immunity. Influenza viruses are serious zoonotic pathogens, causing millions of severe infections and hundreds of thousands of deaths annually. The hnRNP family is known to influence IAV replication and pathogenesis. Here, we demonstrate for the first time that hnRNP D functions as a positive factor for IAV replication. We show that hnRNP D exerts a net promoting effect on viral replication primarily by suppressing the type I interferon response. The mechanism of action involves viral infection upregulating hnRNP D, which interacts with the key transcription factor IRF3, disrupting the TBK1-IRF3 signaling axis. Our findings provide novel insights into how a host RNA-binding protein can be co-opted by IAV to dampen antiviral innate immunity, presenting a potential target for developing new therapeutic strategies against influenza.
Immune checkpoint inhibitors have transformed the treatment of advanced melanoma, yet many patients develop primary or acquired resistance. Although most work has focused on adaptive checkpoints (PD-1 and CTLA-4), accumulating evidence implicates innate immune suppression and stem-like, drug-resistant melanoma cell states. CD24, a small, heavily glycosylated glycosylphosphatidylinositol (GPI)-anchored surface protein, sits at the intersection of these processes and is emerging as a context-dependent biomarker and potential mediator of aggressive, therapy-resistant melanoma states. In this review, we synthesize evidence indicating that CD24 is both a tumour-intrinsic and tumour-extrinsic regulator in melanoma. We summarize the structure, glycosylation and regulation of CD24, then discuss its role in melanoma, supporting phenotypic plasticity, sustaining stem-like populations and promoting resistance to BRAF-targeted and cytotoxic therapies through SOX2/STAT3-linked programmes. We then examine the CD24-Siglec-10 axis as an innate immune checkpoint that suppresses macrophage and dendritic cell function, promotes immune-excluded 'cold' tumour microenvironments and may shape responses to immunotherapy among CD24+ melanoma cells. We highlight CD24 in tumour tissue, blood and extracellular vesicles as potential biomarkers of prognosis and pathway activity, and review CD24-axis interventions, including anti-CD24 antibodies, Siglec-10 antagonists and CD24-targeted CAR-T/CAR-NK cells, with rational combinations alongside PD-1/CTLA-4 blockade and MAPK-targeted therapy. We propose that biomarker-driven trials targeting this axis could open a new front in melanoma immunotherapy.
Inflammation is a physiological and tightly regulated component of normal pregnancy, contributing to implantation, placental development, and the initiation of parturition. The placenta functions as an active immunological hub, coordinating innate and adaptive immune responses to maintain tolerance while protecting against infection. Preeclampsia and fetal growth restriction (FGR) are major causes of maternal and perinatal morbidity worldwide and represent central manifestations of placental disease. Increasing evidence indicates that these conditions share key pathophysiological mechanisms, including placental dysfunction and maladaptive maternal immune responses. When immune regulation at the maternal-fetal interface becomes disrupted, inflammatory pathways contribute to impaired placental development and vascular maladaptation. In this context, excessive immune activation-driven by inflammasome signaling, Th1/Th17 polarization, and altered natural killer and macrophage function-can compromise placental perfusion, promote antiangiogenic imbalance, and lead to systemic endothelial dysfunction. This review, therefore, focuses on how immune dysregulation contributes to placental dysfunction in preeclampsia and FGR, synthesizing current knowledge of the maternal-fetal immune interface and exploring therapeutic strategies that link pathogenic mechanisms to targeted interventions. A deeper understanding of placental immunology and inflammatory signaling is essential to develop precision therapies. Established therapies, including low-dose aspirin, low-molecular-weight heparin, and antenatal corticosteroids, aim to mitigate inflammation and optimize fetal outcomes, while adjunctive strategies target oxidative stress, nutritional deficits, and the maternal microbiome. Emerging approaches such as cytokine-targeted biologics, inflammasome inhibitors, and mesenchymal stem cell therapies show promise but require rigorous safety and efficacy evaluation. Future research should prioritize biomarker validation, pathway-specific interventions, and equitable implementation to reduce inflammation-driven pregnancy complications.
Complicated intra-abdominal infection (cIAI) represents a common and challenging surgical emergency that frequently progresses from localized infection to intra-abdominal sepsis (IAS), leading to rapid clinical deterioration, early organ dysfunction, and unfavorable outcomes. However, the immunological mechanisms underlying these clinical behaviors remain incompletely understood. This review advances a compartment-oriented immunopathological framework to explain the unique behavior of abdominal infection across the cIAI-IAS spectrum. The peritoneal cavity is not an immunologically passive space but a highly specialized immune compartment pre-equipped with fat-associated lymphoid clusters (milky spots), peritoneal resident macrophages (PRMs), B1 cells, and innate lymphoid cells (ILCs). Upon intra-abdominal contamination, this regional immune network enables rapid and high-intensity local inflammatory responses that initially favor containment of polymicrobial infection. However, inadequate or delayed multimodal intervention, together with unfavorable host conditions such as advanced age, immunosuppression, comorbidities, and high disease severity, may permit excessive inflammatory amplification and peritoneal barrier failure within this confined anatomical space. As a consequence, pathogen- and injury-associated signals disseminate rapidly through vascular and lymphatic pathways, driving progression from cIAI to IAS. Together, this compartment-oriented perspective challenges the traditionally source control-focused understanding of cIAI by highlighting the critical role of peritoneal immune compartmentalization, opening avenues for earlier risk stratification and immunologically informed, stratified intervention strategies across the full cIAI-IAS spectrum.
The lack of highly effective disease-modifying treatments for schizophrenia necessitates exploration of novel aspects of its pathophysiology, including attention to innate immune mechanisms outside the brain. C4 protein activation, associated with the complement cascade of innate immunity, associates with symptoms and predicts outcomes in schizophrenia. However, C4 protein activation does not coincide with expected changes to other proteins in the complement cascade, suggesting another source of C4 protein activation. Studying a combination of fresh whole blood from 10 anonymous donors and a large set of publicly available microarray data, we show that C4 protein is found and expressed primarily in neutrophils and monocytes. Then, we compared the correlation between C4 protein in neutrophils, classical monocytes, plasma, and the number of C4A gene copies. We determined the number of C4A genes using digital droplet PCR, C4 protein in neutrophils (15 patients/21 controls) and plasma (30 patients/38 controls) using Western blotting, and classical monocytes (30 patients/38 controls) using flow cytometry. We found a large positive correlation between the number of C4A gene copies and the amount of C4 protein only in neutrophils and only in the schizophrenia group (Spearman's rho = 0.63, 95% BCa CI: 0.12 to 0.89, P = 0.012). Our results indicate a convergence of innate immunity mechanisms associated with schizophrenia. The involvement of innate immunity deserves further attention to determine whether it could be a target for therapy in schizophrenia.
Aim2-like receptors (ALRs) play crucial roles in innate immune signaling pathways and demonstrate strong positive selection likely driven by pathogens. IFI207, an ALR found in all Mus species, enhances interaction with and stabilization of STING, contributing to the control of murine leukemia virus (MLV) infection. We show here that IFI207 enhances the type 1 interferon response by inhibiting activation-induced K63-linked ubiquitination of STING, thereby preventing its recognition by hepatocyte growth factor-regulated tyrosine kinase substrate (HRS), a key component of the ESCRT complex, and its subsequent degradation in lysosomes. IFI207 promotes downstream signaling in the STING pathway in multiple cell types and moreover enhances the STING-dependent response to herpes simplex virus 1 infection ex vivo and in vivo. We also show that IFI207 likely functions in dendritic cells to suppress MLV infection. Our study reveals that IFI207 acts as a modulator in the STING pathway, strengthening the host's defense against viral infections and suggesting that the expansion of the Alr locus in mice may have occurred in response to endemic viruses. The innate immune system serves as a first line of defense by utilizing a variety of pattern recognition receptors (PRRs) that detect various nucleic acids generated during virus infection, many of which activate the STING pathway, leading to interferon production. One family of PRRs, the Aim2-like receptors (ALRs), is thought to contribute to innate immunity by this mechanism. However, the Alr locus is highly polymorphic at the sequence and copy number level. We found that at least one member in mice, IFI207, contributes to innate immunity by preventing the degradation of STING that normally occurs after its activation, defining a novel mechanism for sustaining immune response. Several ALRs have been implicated in adipogenesis, autoimmune disease, and inflammation, and identification of the pressures that shaped the genes in the locus is thus important for understanding the biological processes in which the ALRs function.
SUMMARYEffective immunity requires the ability to mount strong pathogen defenses while minimizing detrimental effects on organismal fitness. To achieve this balance, many immune genes are maintained in a transcriptionally repressed but responsive state, ensuring rapid induction upon infection and timely repression once the threat subsides. This dynamic regulation is controlled by transcription factors and chromatin remodelers that fine-tune the accessibility of immune loci. The nematode Caenorhabditis elegans provides a powerful model for dissecting these mechanisms in non-professional immune cells. Its antiviral RNA interference (RNAi) pathway serves as a rapid, sequence-specific silencing system targeting viral RNA. Complementing RNAi, the intracellular pathogen response represents a specialized, inducible transcriptional program that protects C. elegans from intracellular pathogens, including viruses and microsporidia. In addition, pathways regulated by STAT family transcription factors coordinate immune activation in a pathogen- and tissue-specific manner, providing further regulatory diversity. This review explores how transcriptional and chromatin mechanisms coordinate these distinct immune programs to maintain effective yet balanced immune responses. Investigating these pathways in C. elegans continues to uncover both conserved and novel principles of immune regulation, offering insight into how organisms integrate transcriptional control with physiological constraints to thrive in a pathogen-rich environment.
Skin is a multifunctional organ essential for maintaining body homeostasis, regulating functions and providing protection from environmental stressors. In fish, skin is immune active, containing antimicrobial proteins acting as the first line of defence against infectious pathogens. The gills function similarly, as a key mucosal immunity site, where pathogens induce both innate and adaptive immune responses. In this study, proteomic analysis identified differentially expressed proteins in the skin and gills of ectoparasite Gyrodactylus turnbulli infected guppies (Poecilia reticulata) at two timepoints post-infection (Days 13 and 17). These fish were provided with a health-promoting additive, aimed to boost immunocompetency and reduce ectoparasite infections. Different proteomes were evidenced based on infection status of fish (susceptible, responding, or resistant) and in-feed supplementation. In skin tissue, susceptible fish showed no evidence of immune response, reflecting their high parasite load. Responding fish employed biological processes like apoptosis, reducing the gyrodactylid niche. In resistant fish, up-regulated innate and adaptive immunity explained the low parasite load on the host over the entire infection trajectory. Overall, fish protein expression in the skin and gills was affected both by the dietary supplement and gyrodactylid infection burden, highlighting the role of natural immunostimulants in aquatic infectious disease prophylaxis, control and treatment.
Immune checkpoint blockade (ICB) has transformed cancer therapy; however, its efficacy remains limited in immunologically "cold" tumors such as breast cancer. These tumors are typically characterized by low T-cell infiltration and an immunosuppressive tumor microenvironment (TME), which restrict the effectiveness of current immunotherapies. Therefore, strategies that enhance antigen presentation and promote coordinated activation of innate and adaptive immunity are needed to improve therapeutic outcomes. We developed a lipid nanoparticle platform (IC-LNP) for the co-delivery of interleukin-33 (IL-33) messenger RNA (mRNA) and the stimulator of interferon genes (STING) agonist cyclic di-adenosine monophosphate (c-di-AMP). This formulation enabled sustained intratumoral IL-33 expression and was associated with enhanced dendritic cell maturation and antigen cross-presentation, accompanied by activation of nuclear factor kappa B (NF-κB) signaling. In parallel, c-di-AMP activated the STING pathway, induced type I interferon responses, and enhanced cytotoxic T-cell activity. Consistent with these immunostimulatory effects, IC-LNP increased immune cell infiltration, reduced immunosuppressive cell populations, and shifted the tumor microenvironment toward a more immune-active state. In vivo, IC-LNP improved tumor control and potentiated the therapeutic efficacy of programmed death-ligand 1 (PD-L1) blockade, together with enhanced systemic antitumor immune responses. By enabling the coordinated delivery of IL-33 mRNA and a STING agonist, IC-LNP offers a dual-component immunotherapeutic strategy to enhance innate and adaptive antitumor immunity. These findings provide a basis for further development of combination immunotherapy strategies for poorly immunogenic breast cancer, including strategies to improve responses to checkpoint blockade.
Long non-coding RNAs (LncRNAs) play pivotal regulatory roles in various biological processes, notably in immune regulation and viral infection. We previously identified the broad anti-influenza activity for LncRNA#61. Here, we further investigate the mechanism underlying its antiviral effect, both in vitro and in vivo. Using a lipid-nanoparticle-based delivery strategy, LncRNA#61 was successfully delivered into mice and effectively attenuated the replication and virulence of the highly pathogenic H5N1 influenza virus. Integrative transcriptomic analysis revealed that forced expression of LncRNA#61 markedly activated lipid metabolism, cell death, and Ragulator-Rag-mTORC1 pathways. Quantitative reverse transcription PCR analysis and a targeting metabolic assay further confirmed that LncRNA#61 is actively involved in regulating these pathways. Subsequent functional studies demonstrated that LncRNA#61 consistently enhances GSDMD-mediated pyroptosis both in murine LET-1 and canine MDCK cells. Notably, such pyroptosis was found to restrict H5N1 influenza virus replication. Intriguingly, ectopic expression of viral PA-X protein enhanced antiviral activity of LncRNA#61 both in vitro and in vivo. Mechanistically, PA-X interacts with LncRNA#61 and promotes LncRNA#61-mediated pyroptosis via a RagA-dependent reactive oxygen species pathway. Collectively, we here propose a novel model in which viral and host factors cooperate to activate a pro-death antiviral pathway. Our findings not only advance the fundamental knowledge of virus-host interactions but also cross-link cell death, innate immunity, and metabolic regulation, pinpointing novel therapeutic targets against influenza. A current priority in anti-influenza research is developing broad-spectrum, host-directed therapeutics with low resistance risk. Here, we reveal that LncRNA#61-induced pyroptosis exerts an antiviral effect by restricting H5N1 virus replication both in vitro and in vivo, highlighting a novel cooperative virus-host interaction that enhances antiviral immunity. Key contributions include the following: (i) identifying pyroptosis as a direct executioner mechanism that restricts H5N1 virus infection; (ii) revealing the unexpected role of forced expression of viral PA-X in augmenting antiviral activity of host LncRNA#61; and (iii) deciphering that LncRNA#61 interacts with PA-X and synergistically promotes GSDMD-mediated pyroptosis through a RagA‑ROS signaling cascade. Collectively, our work elucidates a novel antiviral mechanism wherein host LncRNA and viral protein co-opt the RagA-ROS-GSDMD axis to drive pyroptosis and inhibit viral replication. This discovery innovatively establishes a novel connection among viral pathogenesis, host cell death, and cellular metabolism, offering a fresh, integrative perspective for future studies on host-directed antiviral strategies.
Neutrophils are the most abundant circulating leukocytes and are characterized by a proteome in which granule-associated proteins synthesized during granulopoiesis constitute a major fraction of total cellular protein, reflecting their preloaded effector nature in innate immune defense. A striking feature of neutrophil biology is the unusual abundance of the calcium-binding proteins S100A8 and S100A9, which together form the heterodimeric complex known as calprotectin. Early biochemical studies estimated that S100A8/A9 constitutes a substantial fraction of the soluble cytosolic proteome in neutrophils, with later studies often describing it as one of the most abundant protein complexes in these cells. Despite extensive studies on the antimicrobial and inflammatory activities of calprotectin, the biological rationale for this unusual abundance remains incompletely understood. In this review, we examine the structural, biochemical, and regulatory features of S100A8/A9 and explore the potential explanations for its high abundance in the neutrophil cytosol. We first discuss the unique organization of the neutrophil proteome and the transcriptional programs governing granulopoiesis that lead to large-scale production of neutrophil effector proteins. We then review the structural and biochemical properties of S100A8/A9, including its calcium-dependent conformational dynamics and high-affinity transition metal binding, which contribute to antimicrobial defense through nutritional immunity. Several functional hypotheses are considered to explain calprotectin abundance, including roles as an antimicrobial reservoir, a metal-sequestering molecule, a regulator of oxidative stress, and a source of damage-associated molecular patterns. Finally, we discuss the evolutionary logic of neutrophil protein preloading and the implications of calprotectin biology in inflammatory diseases and the tumor microenvironment. Resolving the abundance paradox of S100A8/A9 may reveal fundamental principles governing the organization of innate immune cell proteomes and provide new insights into the strategies used by neutrophils to achieve rapid and effective host defense.
Anthracnose disease, caused by Colletotrichum species, poses a significant threat to global litchi production, yet the molecular mechanisms governing host resistance remain poorly understood. To dissect the genetic basis of anthracnose resistance, we employed a comparative transcriptomic approach using two contrasting cultivars: 'YuJinQiu' (DR, disease-resistant genotype) and 'BaiTangYing' (DS, disease-susceptible genotype). Field evaluations and controlled infection assays demonstrated evident phenotypic divergence, with DR exhibiting delayed disease progression and 43.7% smaller lesion areas compared to DS at 72 h post-inoculation (hpi). Time-resolved RNA sequencing (0-72 hpi) revealed genotype-specific transcriptional dynamics, where DR displayed fewer differentially expressed genes (DEGs; 819-1457) compared to DS (5195-5735), suggesting a more targeted and efficient defense response. Functional enrichment analyses highlighted rapid activation of innate immunity pathways in DR, including pattern-triggered immunity, MAPK signaling, and jasmonic acid/ethylene biosynthesis, whereas DS prioritized cell wall modification and compensatory secondary metabolic processes. Weighted gene co-expression network analysis (WGCNA) pinpointed three modules tightly linked to anthracnose resistance, enriched for receptor-like kinases (RLKs), nucleotide-binding leucine-rich repeat (NLR) proteins, and phenylpropanoid biosynthesis genes. Hub regulators, including WRKY transcription factors (e.g., WRKY33), ubiquitin ligases, and pathogenesis-related proteins (PR1, PR5), were identified as central coordinators of defense signaling. Strikingly, DR exhibited sustained upregulation of effector-triggered immunity markers, particularly nucleotide-binding leucine-rich repeat (NLR) genes, and early accumulation of phytoalexins, correlating with pathogen suppression. Experimental validation via qRT-PCR confirmed the reliability of transcriptomic data. Our study unravels the multilayer regulatory network underlying litchi anthracnose resistance, providing not only a mechanistic model of cultivar-specific responses but also a robust gene toolkit for accelerating the development of resistant cultivars through marker-assisted breeding.