Self-regulation and cross-regulation of pattern-recognition receptor signalling in health and disease

mRNA vaccines contribute to innate and adaptive immunity to enhance immune response in vivo

Messenger RNA (mRNA) therapeutics have been widely employed as strategies for the treatment and prevention of diseases. Amid the global outbreak of COVID-19, mRNA vaccines have witnessed rapid development. Generally, in the case of mRNA vaccines, the initiation of the innate immune system serves as a prerequisite for triggering subsequent adaptive immune responses. Critical cells, cytokines, and chemokines within the innate immune system play crucial and beneficial roles in coordinating tailored immune reactions towards mRNA vaccines. Furthermore, immunostimulators and delivery systems play a significant role in augmenting the immune potency of mRNA vaccines. In this comprehensive review, we systematically delineate the latest advancements in mRNA vaccine research, present an in-depth exploration of strategies aimed at amplifying the immune effectiveness of mRNA vaccines, and offer some perspectives and recommendations regarding the future advancements in mRNA vaccine development.

USP46 promotes the interferon antiviral signaling in black carp by deubiquitinating TBK1

Ubiquitin-specific peptidase 46 (USP46) functions as a deubiquitinating enzyme, facilitating the removal of ubiquitin molecules attached to substrate proteins and playing a critical role in cancer and neurodegenerative diseases. However, its function in innate antiviral immunity is unknown. In this study we cloned and identified bcUSP46, a homolog of USP46 from black carp. We discovered that overexpression of bcUSP46 enhanced the transcription of interferon (IFN) promoters and increased the expression of IFN, PKR, and Mx1. In addition, bcUSP46 knockdown significantly inhibited the expression of ISG genes, as well as the antiviral activity of the host cells. Interestingly, when bcUSP46 was co-expressed with the RLR factors, it significantly enhanced the activity of the IFN promoter mediated by these factors, especially TANK-binding kinase 1 (TBK1). The subsequent co-immunoprecipitation (co-IP) and immunofluorescence (IF) assay confirmed the association between bcUSP46 and bcTBK1. Noteworthily, co-expression of bcUSP46 with bcTBK1 led to an elevation of bcTBK1 protein level. Further analysis revealed that bcUSP46 stabilized bcTBK1 by eliminating the K48-linked ubiquitination of bcTBK1. Overall, our findings highlight the unique role of USP46 in modulating TBK1/IFN signaling and enrich our knowledge of the function of deubiquitination in regulating innate immunity in vertebrates.

Guanylate-binding protein 1 inhibits inflammatory factors produced by H5N1 virus through Its GTPase activity

The combination of inflammatory factors resulting from an influenza A virus infection is one of the main causes of death in host animals. Studies have shown that guinea pig guanosine monophosphate binding protein 1 (guanylate-binding protein 1, gGBP1) can downregulate cytokine production induced by the influenza virus. Therefore, exploring the innate immune defense mechanism of GBP1 in the process of H5N1 influenza virus infection has important implications for understanding the pathogenic mechanism, disease prevention, and the control of influenza A virus infections. We found that, in addition to inhibiting the early replication of influenza virus, gGBP1 also inhibited the production of CCL2 and CXCL10 cytokines induced by the influenza virus as well as the proliferation of mononuclear macrophages induced by these cytokines. These findings further confirmed that gGBP1 inhibited the production of cytokines through its GTPase activity and cell proliferation through its C-terminal α-helix structure. This study revealed the effect of gGBP1 on the production of cellular inflammatory factors during influenza virus infection and determined the key amino acid residues that assist in the inhibitory processes mediated by gGBP1.

Dual inhibitors of DNMT and HDAC remodels the immune microenvironment of colorectal cancer and enhances the efficacy of anti-PD-L1 therapy

Colorectal cancer is the second most prevalent and deadly cancer worldwide. The emergence of immune checkpoint therapy has provided a revolutionary strategy for the treatment of solid tumors. However, less than 5% of colorectal cancer patients respond to immune checkpoint therapy. Thus, it is of great scientific significance to develop "potentiators" for immune checkpoint therapy. In this study, we found that knocking down different DNMT and HDAC isoforms could increase the expression of IFNs in colorectal cancer cells, which can enhance the effectiveness of immune checkpoint therapy. Therefore, the combined inhibition of DNMT and HDAC cloud synergistically enhance the effect of immunotherapy. We found that dual DNMT and HDAC inhibitors C02S could inhibit tumor growth in immunocompetent mice but not in immunocompromised nude mice, which indicates that C02S exerts its antitumor effects through the immune system. Mechanistically, C02S could increase the expression of ERVs, which generated the intracellular levels of dsRNA in tumor cells, and then promotes the expression of IFNs through the RIG-I/MDA5-MAVS signaling pathway. Moreover, C02S increased the immune infiltration of DCs and T cells in microenvironment, and enhanced the efficacy of anti-PD-L1 therapy in MC38 and CT26 mice model. These results confirmed that C02S can activate IFNs through the RIG-I/MDA5-MAVS signaling pathway, remodel the tumor immune microenvironment and enhance the efficacy of immune checkpoint therapy, which provides new evidence and solutions for the development of "potentiator" for colorectal cancer immunotherapy.

T Cell-Derived Apoptotic Extracellular Vesicles Hydrolyze cGAMP to Alleviate Radiation Enteritis via Surface Enzyme ENPP1

Radiation enteritis is the most common complication of pelvic radiotherapy, but there is no effective prevention or treatment drug. Apoptotic T cells and their products play an important role in regulating inflammation and maintaining physiological immune homeostasis. Here it is shown that systemically infused T cell-derived apoptotic extracellular vesicles (ApoEVs) can target mice irradiated intestines and alleviate radiation enteritis. Mechanistically, radiation elevates the synthesis of intestinal 2'3' cyclic GMP-AMP (cGAMP) and activates cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) proinflammatory pathway. After systemic infusion of ApoEVs, the ectonucleotide pyrophosphatase phosphodiesterase 1 (ENPP1) enriches on the surface of ApoEVs hydrolyze extracellular cGAMP, resulting in inhibition of the cGAS-STING pathway activated by irradiation. Furthermore, after ApoEVs are phagocytosed by phagocytes, ENPP1 on ApoEVs hydrolyzed intracellular cGAMP, which serves as an intracellular cGAMP hydrolyzation mode, thereby alleviating radiation enteritis. The findings shed light on the intracellular and extracellular hydrolysis capacity of ApoEVs and their role in inflammation regulation.

Host Factors Modulate Virus-Induced IFN Production via Pattern Recognition Receptors

Innate immunity is the first line of defense in the human body, and it plays an important role in defending against viral infection. Viruses are identified by different pattern-recognition receptors (PRRs) that activate the mitochondrial antiviral signaling protein (MAVS) or transmembrane protein 173 (STING), which trigger multiple signaling cascades that cause nuclear factor-κB (NF-κB) and interferon regulatory factor 3 (IRF3) to produce inflammatory factors and interferons (IFNs). PRRs play a pivotal role as the first step in pathogen induction of interferon production. Interferon elicits antiviral activity by inducing the transcription of hundreds of IFN-stimulated genes (ISGs) via the janus kinase (JAK) - signal transducer and activator of transcription (STAT) pathway. An increasing number of studies have shown that environmental, pathogen and host factors regulate the IFN signaling pathway. Here, we summarize the mechanisms of host factor modulation in IFN production via pattern recognition receptors. These regulatory mechanisms maintain interferon levels in a normal state and clear viruses without inducing autoimmune disease.

Impacts of preparation technologies on biological activities of edible mushroom polysaccharides - novel insights for personalized nutrition achievement

Edible mushroom polysaccharides (EMPs) as a natural macromolecular carbohydrate have a very complex structure and composition. EMPs are considered ideal candidates for developing healthy products and functional foods and have received significant research attention due to their unique physiological activities such as immunomodulatory, anti-inflammatory, anti-tumor/cancer, gut microbiota regulation, metabolism improvement, and nervous system protection. The structure and monosaccharide composition of edible mushroom polysaccharides have an unknown relationship with their functional activity, which has not been widely studied. Therefore, we summarized the preparation techniques of EMPs and discussed the association between functional activity, preparation methods, structure and composition of EMPs, laying a theoretical foundation for the personalized nutritional achievements of EMP. We also establish the foundation for the further investigation and application of EMPs as novel functional foods and healthy products.

Bovine DDX3X Restrains Bovine SP110c-Mediated Activation of Inflammasome in Macrophages

The inflammasome is a vital part of the host's innate immunity activated by cellular infection or stress. Our previous research identified the bovine SP110c isoform (bSP110c) as a novel activator of the inflammasome that promoted the secretion of proinflammatory cytokines IL-1β and IL-18 in macrophages infected with Listeria monocytogenes or stimulated with lipopolysaccharide (LPS). However, the exact molecular mechanism for inhibiting bSP110c-induced inflammasome activation requires further clarification. Here, the researchers identified bovine DDX3X (bDDX3X) as an NLRP3-associated protein and an inhibitor of the bSP110c-induced inflammasome in the human THP1 macrophage cell line. Immunoprecipitation showed that bDDX3X interacted with the bSP110c CARD domain via its helicase domain. The co-expression of bSP110c and bDDX3X in THP1 macrophages significantly prevented the bSP110c-induced activation of inflammasomes. In addition, both bDDX3X and bSP110c interacted with bovine NLRP3 (bNLRP3), and bDDX3X enhanced the interaction between bSP110c and bNLRP3. The expression of bDDX3X in nigericin-stimulated THP1 macrophages significantly suppressed NLRP3 inflammasome activation, ASC speck formation, and pyroptosis. These findings demonstrate that bDDX3X negatively regulates the bSP110c-mediated inflammatory response by restricting the activation of the NLRP3 inflammasome. This discovery unveils a novel regulatory mechanism involving bDDX3X and bSP110c in coordinating inflammasome activation and subsequent cell-fate decisions in LPS-treated macrophages and, in turn, constitutes a step forward toward the implementation of marker-assisted selection in breeding programs aimed at utilizing cattle's immune defenses.

Effect of ethanol exposure on innate immune response in sepsis

Alcohol use disorder, reported by 1 in 8 critically ill patients, is a risk factor for death in sepsis patients. Sepsis, the leading cause of death, kills over 270,000 patients in the United States alone and remains without targeted therapy. Immune response in sepsis transitions from an early hyperinflammation to persistent inflammation and immunosuppression and multiple organ dysfunction during late sepsis. Innate immunity is the first line of defense against pathogen invasion. Ethanol exposure is known to impair innate and adaptive immune response and bacterial clearance in sepsis patients. Specifically, ethanol exposure is known to modulate every aspect of innate immune response with and without sepsis. Multiple molecular mechanisms are implicated in causing dysregulated immune response in ethanol exposure with sepsis, but targeted treatments have remained elusive. In this article, we outline the effects of ethanol exposure on various innate immune cell types in general and during sepsis.

Advanced Immunomodulatory Biomaterials for Therapeutic Applications

The multifaceted biological defense system modulating complex immune responses against pathogens and foreign materials plays a critical role in tissue homeostasis and disease progression. Recently developed biomaterials that can specifically regulate immune responses, nanoparticles, graphene, and functional hydrogels have contributed to the advancement of tissue engineering as well as disease treatment. The interaction between innate and adaptive immunity, collectively determining immune responses, can be regulated by mechanobiological recognition and adaptation of immune cells to the extracellular microenvironment. Therefore, applying immunomodulation to tissue regeneration and cancer therapy involves manipulating the properties of biomaterials by tailoring their composition in the context of the immune system. This review provides a comprehensive overview of how the physicochemical attributes of biomaterials determine immune responses, focusing on the physical properties that influence innate and adaptive immunity. This review also underscores the critical aspect of biomaterial-based immune engineering for the development of novel therapeutics and emphasizes the importance of understanding the biomaterials-mediated immunological mechanisms and their role in modulating the immune system.

Zebrafish mylipb attenuates antiviral innate immunity through two synergistic mechanisms targeting transcription factor irf3

IFN regulatory factor 3 (IRF3) is the transcription factor crucial for the production of type I IFN in viral defence and inflammatory responses. The activity of IRF3 is strictly modulated by post-translational modifications (PTMs) to effectively protect the host from infection while avoiding excessive immunopathology. Here, we report that zebrafish myosin-regulated light chain interacting protein b (mylipb) inhibits virus-induced type I IFN production via two synergistic mechanisms: induction of autophagic degradation of irf3 and reduction of irf3 phosphorylation. In vivo, mylipb-null zebrafish exhibit reduced lethality and viral mRNA levels compared to controls. At the cellular level, overexpression of mylipb significantly reduces cellular antiviral capacity, and promotes viral proliferation. Mechanistically, mylipb associates with irf3 and targets Lys 352 to increase K6-linked polyubiquitination, dependent on its E3 ubiquitin ligase activity, leading to autophagic degradation of irf3. Meanwhile, mylipb acts as a decoy substrate for the phosphokinase tbk1 to attenuate irf3 phosphorylation and cellular antiviral responses independent of its enzymatic activity. These findings support a critical role for zebrafish mylipb in the limitation of antiviral innate immunity through two synergistic mechanisms targeting irf3.

Chimeric NOD2 Mincle Agonists as Vaccine Adjuvants

There is a need for improved vaccine adjuvants to augment vaccine efficacy. One way to address this is by targeting multiple immune cell pathogen recognition receptors (PRRs) using chimeric pathogen-associated molecular patterns (PAMPs). Conjugation of the PAMPs will ensure codelivery of the immunostimulatory molecules to the same cell, enhancing adjuvant activity. The macrophage inducible C-type lectin (Mincle) is a promising PRR for adjuvant development; however, no effective chimeric Mincle adjuvants have been prepared. We addressed this by synthesizing Mincle adjuvant conjugates, MDP-C18Brar and MDP-C18Brar-dilipid, which contain PAMPs recognized by Mincle and the nucleotide-binding oligomerization domain 2 (NOD2). The two PAMPs are joined by a pH-sensitive oxyamine linker which, upon acidification at lysosomal pH, hydrolyzed to release the NOD2 ligands. The conjugates elicited the production of Th1 and Th17 promoting cytokines in vitro, and when using OVA as a model antigen, exhibited enhanced T-cell-mediated immune responses and reduced toxicity in vivo, compared to the coadministration of the adjuvants.

PADI4 negatively regulates RIG-I-mediated antiviral response through deacetylation of IFN-β promoter via HDAC1

The production of type I interferon (IFN) is precisely modulated by host to protect against viral infection efficiently without obvious immune disorders. Elucidating the tight control towards type I IFN production would be helpful to get insight into natural immunity and inflammatory diseases. As yet, however, the mechanisms that regulate IFN-β production, especially the epigenetic regulatory mechanisms, remain poorly explored. This study elucidated the potential function of Peptidylarginine deiminases (PADIs)-mediated citrullination in innate immunity. We identified PADI4, a PADIs family member that can act as an epigenetic coactivator, could repress IFN-β production upon RNA virus infection. Detailed experiments showed that PADI4 deficiency increased IFN-β production and promoted antiviral immune activities against RNA viruses. Mechanistically, the increased PADI4 following viral infection translocated to nucleus and recruited HDAC1 upon binding to Ifnb1 promoter, which then led to the deacetylation of histone H3 and histone H4 for repressing Ifnb1 transcription. Taken together, we identify a novel non-classical role for PADI4 in the regulation of IFN-β production, suggesting its potential as treatment target in inflammatory or autoimmune diseases.

Proof of concept in utilizing the peptidoglycan skeleton of pathogenic bacteria as antigen delivery platform for enhanced immune response

Subunit vaccines are becoming increasingly important because of their safety and effectiveness. However, subunit vaccines often exhibit limited immunogenicity, necessitating the use of suitable adjuvants to elicit robust immune responses. In this study, we demonstrated for the first time that pathogenic bacteria can be prepared into a purified peptidoglycan skeleton without nucleic acids and proteins, presenting bacterium-like particles (pBLP). Our results showed that the peptidoglycan skeletons screened from four pathogens could activate Toll-like receptor1/2 receptors better than bacterium-like particles from Lactococcus lactis in macrophages. We observed that pBLP was safe in mouse models of multiple ages. Furthermore, pBLP improved the performance of two commercial vaccines in vivo. We confirmed that pBLP successfully loaded antigens onto the surface and proved to be an effective antigen delivery platform with enhanced antibody titers, antibody avidity, balanced subclass distribution, and mucosal immunity. These results indicate that the peptidoglycan skeleton of pathogenic bacteria represents a new strategy for developing subunit vaccine delivery systems.

The emerging role of hypoxia and environmental factors in inflammatory bowel disease

Inflammatory bowel disease (IBD) is a chronic and debilitating disorder characterized by inflammation of the gastrointestinal tract. Despite extensive research, the exact cause of IBD remains unknown, hampering the development of effective therapies. However, emerging evidence suggests that hypoxia, a condition resulting from inadequate oxygen supply, plays a crucial role in intestinal inflammation and tissue damage in IBD. Hypoxia-inducible factors (HIFs), transcription factors that regulate the cellular response to low oxygen levels, have gained attention for their involvement in modulating inflammatory processes and maintaining tissue homeostasis. The two most studied HIFs, HIF-1α and HIF-2α, have been implicated in the development and progression of IBD. Toxicological factors encompass a wide range of environmental and endogenous agents, including dietary components, microbial metabolites, and pollutants. These factors can profoundly influence the hypoxic microenvironment within the gut, thereby exacerbating the course of IBD and fostering the progression of colitis-associated colorectal cancer. This review explores the regulation of hypoxia signaling at the molecular, microenvironmental, and environmental levels, investigating the intricate interplay between toxicological factors and hypoxic signaling in the context of IBD, focusing on its most concerning outcomes: intestinal fibrosis and colorectal cancer.

The contribution of pattern recognition receptor signalling in the development of age related macular degeneration: the role of toll-like-receptors and the NLRP3-inflammasome

Age-related macular degeneration (AMD) is a leading cause of irreversible vision loss, characterised by the dysfunction and death of the photoreceptors and retinal pigment epithelium (RPE). Innate immune cell activation and accompanying para-inflammation have been suggested to contribute to the pathogenesis of AMD, although the exact mechanism(s) and signalling pathways remain elusive. Pattern recognition receptors (PRRs) are essential activators of the innate immune system and drivers of para-inflammation. Of these PRRs, the two most prominent are (1) Toll-like receptors (TLR) and (2) NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3)-inflammasome have been found to modulate the progression of AMD. Mutations in TLR2 have been found to be associated with an increased risk of developing AMD. In animal models of AMD, inhibition of TLR and NLRP3 has been shown to reduce RPE cell death, inflammation and angiogenesis signalling, offering potential novel treatments for advanced AMD. Here, we examine the evidence for PRRs, TLRs2/3/4, and NLRP3-inflammasome pathways in macular degeneration pathogenesis.

Sterile inflammation via TRPM8 RNA-dependent TLR3-NF-kB/IRF3 activation promotes antitumor immunity in prostate cancer

Inflammation is a common condition of prostate tissue, whose impact on carcinogenesis is highly debated. Microbial colonization is a well-documented cause of a small percentage of prostatitis cases, but it remains unclear what underlies the majority of sterile inflammation reported. Here, androgen- independent fluctuations of PSA expression in prostate cells have lead us to identify a prominent function of the Transient Receptor Potential Cation Channel Subfamily M Member 8 (TRPM8) gene in sterile inflammation. Prostate cells secret TRPM8 RNA into extracellular vesicles (EVs), which primes TLR3/NF-kB-mediated inflammatory signaling after EV endocytosis by epithelial cancer cells. Furthermore, prostate cancer xenografts expressing a translation-defective form of TRPM8 RNA contain less collagen type I in the extracellular matrix, significantly more infiltrating NK cells, and larger necrotic areas as compared to control xenografts. These findings imply sustained, androgen-independent expression of TRPM8 constitutes as a promoter of anticancer innate immunity, which may constitute a clinically relevant condition affecting prostate cancer prognosis.

Methyltransferase Setd2 prevents T cell-mediated autoimmune diseases via phospholipid remodeling

Coordinated metabolic reprogramming and epigenetic remodeling are critical for modulating T cell function and differentiation. However, how the epigenetic modification controls Th17/Treg cell balance via metabolic reprogramming remains obscure. Here, we find that Setd2, a histone H3K36 trimethyltransferase, suppresses Th17 development but promotes iTreg cell polarization via phospholipid remodeling. Mechanistically, Setd2 up-regulates transcriptional expression of lysophosphatidylcholine acyltransferase 4 (Lpcat4) via directly catalyzing H3K36me3 of Lpcat4 gene promoter in T cells. Lpcat4-mediated phosphatidylcholine PC(16:0,18:2) generation in turn limits endoplasmic reticulum stress and oxidative stress. These changes decrease HIF-1α transcriptional activity and thus suppress Th17 but enhance Treg development. Consistent with this regulatory paradigm, T cell deficiency of Setd2 aggravates neuroinflammation and demyelination in experimental autoimmune encephalomyelitis due to imbalanced Th17/Treg cell differentiation. Overall, our data reveal that Setd2 acts as an epigenetic brake for T cell-mediated autoimmunity through phospholipid remodeling, suggesting potential targets for treating neuroinflammatory diseases.

A Razor's Edge: Vascular Responses to Acute Inflammatory Lung Injury/Acute Respiratory Distress Syndrome

Historically considered a metabolically inert cellular layer separating the blood from the underlying tissue, the endothelium is now recognized as a highly dynamic, metabolically active tissue that is critical to organ homeostasis. Under homeostatic conditions, lung endothelial cells (ECs) in healthy subjects are quiescent, promoting vasodilation, platelet disaggregation, and anti-inflammatory mechanisms. In contrast, lung ECs are essential contributors to the pathobiology of acute respiratory distress syndrome (ARDS), as the quiescent endothelium is rapidly and radically altered upon exposure to environmental stressors, infectious pathogens, or endogenous danger signals into an effective and formidable regulator of innate and adaptive immunity. These dramatic perturbations, produced in a tsunami of inflammatory cascade activation, result in paracellular gap formation between lung ECs, sustained lung edema, and multi-organ dysfunction that drives ARDS mortality. The astonishing plasticity of the lung endothelium in negotiating this inflammatory environment and efforts to therapeutically target the aberrant ARDS endothelium are examined in further detail in this review.

Unmasking Chemokine-Inducing Specificity in Oligosaccharide Biomaterial to Promote Hair Growth

Hair loss affects over 50 million people worldwide with limited therapeutic options. Despite evidence highlighting the vital role of local immune cells in regulating the life cycle of hair follicles (HFs), accurate regulation of immunocytes to directly promote hair growth remains unachieved. Here, inspired by the physiological feedback in the skin immunity to suppress microbe-triggered inflammation, an oligosaccharide biomaterial with "unmasked" specific activity is developed to recruit regulatory T (Treg ) cells around HFs, leading to accelerated hair growth in mice. By processing the glucomannan polysaccharide via controllable enzymatic cleavage, a series of oligosaccharide fractions with more specific chemokine-inducing functions is obtained. Notably, a hexasaccharide-based fraction (OG6) stimulates macrophages to selectively express Treg -chemoattractant C-C Motif Chemokine Ligand 5 (CCL5) through a mannose receptor-mediated endocytosis and NOD1/2-dependent signaling, as evidenced by molecular docking, inhibition assays, and a Foxp3-reporter mouse model. Intradermal delivery of OG6 to the depilated mouse skin promotes Treg mobilization around HFs and stimulates de novo regeneration of robust hairs. This study demonstrates that unmasking precise immunomodulatory functions in oligosaccharides from their parental polysaccharide can potentially solve the long-lasting dilemma with polysaccharide biomaterials that are widely renowned for versatile activities yet high heterogeneity, opening new avenues to designing glycan-based therapeutic tools with improved specificity and safety.

DAMPs and radiation injury

The heightened risk of ionizing radiation exposure, stemming from radiation accidents and potential acts of terrorism, has spurred growing interests in devising effective countermeasures against radiation injury. High-dose ionizing radiation exposure triggers acute radiation syndrome (ARS), manifesting as hematopoietic, gastrointestinal, and neurovascular ARS. Hematopoietic ARS typically presents with neutropenia and thrombocytopenia, while gastrointestinal ARS results in intestinal mucosal injury, often culminating in lethal sepsis and gastrointestinal bleeding. This deleterious impact can be attributed to radiation-induced DNA damage and oxidative stress, leading to various forms of cell death, such as apoptosis, necrosis and ferroptosis. Damage-associated molecular patterns (DAMPs) are intrinsic molecules released by cells undergoing injury or in the process of dying, either through passive or active pathways. These molecules then interact with pattern recognition receptors, triggering inflammatory responses. Such a cascade of events ultimately results in further tissue and organ damage, contributing to the elevated mortality rate. Notably, infection and sepsis often develop in ARS cases, further increasing the release of DAMPs. Given that lethal sepsis stands as a major contributor to the mortality in ARS, DAMPs hold the potential to function as mediators, exacerbating radiation-induced organ injury and consequently worsening overall survival. This review describes the intricate mechanisms underlying radiation-induced release of DAMPs. Furthermore, it discusses the detrimental effects of DAMPs on the immune system and explores potential DAMP-targeting therapeutic strategies to alleviate radiation-induced injury.

Copper regulates the host innate immune response against bacterial infection via activation of ALPK1 kinase

Copper is an essential trace element for the human body, and its requirement for optimistic immune functions has been recognized for decades. How copper is involved in the innate immune pathway, however, remains to be clarified. Here, we report that copper serves as a signal molecule to regulate the kinase activity of alpha-kinase 1 (ALPK1), a cytosolic pattern-recognition receptor (PRR), and therefore promotes host cell defense against bacterial infection. We show that in response to infection, host cells actively accumulate copper in the cytosol, and the accumulated cytosolic copper enhances host cell defense against evading pathogens, including intracellular and, unexpectedly, extracellular bacteria. Subsequently, we demonstrate that copper activates the innate immune pathway of host cells in an ALPK1-dependent manner. Further mechanistic studies reveal that copper binds to ALPK1 directly and is essential for the kinase activity of this cytosolic PRR. Moreover, the binding of copper to ALPK1 enhances the sensitivity of ALPK1 to the bacterial metabolite ADP-heptose and eventually prompts host cells to elicit an enhanced immune response during bacterial infection. Finally, using a zebrafish in vivo model, we show that a copper-treated host shows an increased production of proinflammatory cytokines, enhanced recruitment of phagosome cells, and promoted bacterial clearance. Our findings uncover a previously unrecognized role of copper in the modulation of host innate immune response against bacterial pathogens and advance our knowledge on the cross talk between cytosolic copper homeostasis and immune system.

The aldehyde dehydrogenase ALDH1B1 exerts antiviral effects through the aggregation of the adaptor MAVS

Type I interferons (IFNs) are produced by almost all cell types and play a vital role in host defense against viral infection. Infection with an RNA virus activates receptors such as RIG-I, resulting in the recruitment of the adaptor protein MAVS to the RIG-I-like receptor (RLR) signalosome and the formation of prion-like functional aggregates of MAVS, which leads to IFN-β production. Here, we identified the aldehyde dehydrogenase 1B1 (ALDH1B1) as a previously uncharacterized IFN-stimulated gene (ISG) product with critical roles in the antiviral response. Knockout of ALDH1B1 increased, whereas overexpression of ALDH1B1 restricted, the replication of RNA viruses, such as vesicular stomatitis virus (VSV), Zika virus (ZIKV), dengue virus (DENV), and influenza A virus (IAV). We found that ALDH1B1 localized to mitochondria, where it interacted with the transmembrane domain of MAVS to promote MAVS aggregation. ALDH1B1 was recruited to MAVS aggregates. In addition, ALDH1B1 also enhanced the interaction between activated RIG-I and MAVS, thus increasing IFN-β production and the antiviral response. Furthermore, Aldh1b1-/- mice developed more severe symptoms than did wild-type mice upon IAV infection. Together, these data identify an aldehyde dehydrogenase in mitochondria that functionally regulates MAVS-mediated signaling and the antiviral response.

Immuno-Enhancing Effect of Ginsenoside Rh2 Liposomes on Foot-and-Mouth Disease Vaccine

The adjuvant is essential for vaccines because it can enhance or directly induce a strong immune response associated with vaccine antigens. Ginsenoside Rh2 (Rh2) had immunomodulatory effects but was limited by poor solubility and hemolysis. In this study, Rh2 liposomes (Rh2-L) were prepared by ethanol injection methods. The Rh2-L effectively dispersed in a double emulsion adjuvant system to form a Water-in-Oil-in-Water (W/O/W) emulsion and had no hemolysis. The physicochemical properties of the adjuvants were tested, and the immune activity and auxiliary effects indicated by the Foot-and-Mouth disease (FMDV) antigen were evaluated. Compared with the mice vaccinated with the FMD vaccine prepared with the double emulsion adjuvant alone, those with the FMD vaccine prepared with the double emulsion adjuvant containing Rh2-L had significantly higher neutralizing antibody titer and splenocyte proliferation rates and showed higher cellular and humoral immune responses. The results demonstrated that Rh2-L could further enhance the immune effect of the double emulsion adjuvant against Foot-and-Mouth Disease.

Glucosylation endows nanoparticles with TLR4 agonist capability to trigger macrophage polarization and augment antitumor immunity

Carbohydrates have emerged as promising candidates for immunomodulation, however, how to present them to immune cells and achieve potent immunostimulatory efficacy remains challenging. Here, we proposed and established an effective way of designing unique glyconanoparticles that can amplify macrophage-mediated immune responses through structural mimicry and multiple stimulation. We demonstrate that surface modification with glucose can greatly augment the immunostimulatory efficacy of nanoparticles, comparing to mannose and galactose. In vitro studies show that glucosylation improved the pro-inflammatory efficacy of iron oxide nanoparticles (IONPs) by up to 300-fold, with the immunostimulatory activity of glucosylated IONPs even surpassing that of LPS under certain conditions. In vivo investigation show that glucosylated IONPs elicited increased antitumor immunity and achieved favorable therapeutic outcomes in multiple murine tumor models. Mechanistically, we proposed that glucosylation potentiated the immunostimulatory effect of IONPs by amplifying toll-like receptors 4 (TLR4) activation. Specifically, glucosylated IONPs directly interacted with the TLR4-MD2 complex, resulting in M1 macrophage polarization and enhanced antitumor immunity via activation of NF-κB, MAPK, and STAT1 signaling pathways. Our work provides a simple modification strategy to endow nanoparticles with potent TLR4 agonist effects, which may shed new light on the development of artificial immune modulators for cancer immunotherapy.

Microbes mediated immunogenic cell death in cancer immunotherapy

Immunogenic cell death (ICD) is one of the 12 distinct cell death forms, which can trigger immune system to fight against cancer cells. During ICD, a number of cellular changes occur that can stimulate an immune response, including the release of molecules called damage-associated molecular patterns (DAMPs), signaling to immune cells to recognize and attack cancer cells. By virtue of their pivotal role in immune surveillance, ICD-based drug development has been a new approach to explore novel therapeutic combinations and personalized strategies in cancer therapy. Several small molecules and microbes can induce ICD-relevant signals and cause cancer cell death. In this review, we highlighted the role of microbe-mediate ICD in cancer immunotherapy and described the mechanisms through which microbes might serve as ICD inducers in cancer treatment. We also discussed current attempts to combine microbes with chemotherapy regimens or immune checkpoint inhibitors (ICIs) in the treatment of cancer patients. We surmise that manipulation of microbes may guide personalized therapeutic interventions to facilitate anticancer immune response.

Nuclear RPSA senses viral nucleic acids to promote the innate inflammatory response

Innate sensors initiate the production of type I interferons (IFN-I) and proinflammatory cytokines to protect host from viral infection. Several innate nuclear sensors that mainly induce IFN-I production have been identified. Whether there exist innate nuclear sensors that mainly induce proinflammatory cytokine production remains to be determined. By functional screening, we identify 40 S ribosomal protein SA (RPSA) as a nuclear protein that recognizes viral nucleic acids and predominantly promotes proinflammatory cytokine gene expression in antiviral innate immunity. Myeloid-specific Rpsa-deficient mice exhibit less innate inflammatory response against infection with Herpes simplex virus-1 (HSV-1) and Influenza A virus (IAV), the viruses replicating in nucleus. Mechanistically, nucleus-localized RPSA is phosphorylated at Tyr204 upon infection, then recruits ISWI complex catalytic subunit SMARCA5 to increase chromatin accessibility of NF-κB to target gene promotors without affecting innate signaling. Our results add mechanistic insights to an intra-nuclear way of initiating proinflammatory cytokine expression in antiviral innate defense.

DNA methylation and gene expression changes in mouse mammary tissue during successive lactations: part I - the impact of inflammation

Mastitis is among the main reasons women cease breastfeeding, which leads to them supplementing breast milk with artificial formula. In farm animals, mastitis results in significant economic losses and the premature culling of some animals. Nevertheless, researchers do not know enough about the effect of inflammation on the mammary gland. This article discusses the changes to DNA methylation in mouse mammary tissue caused by lipopolysaccharide-induced inflammation (4 h post-injection of lipopolysaccharide). We analysed the expression of some genes related to mammary gland function, epigenetic regulation, and the immune response. The analysis focused on three comparisons: inflammation during the first lactation, inflammation during second lactation with no history of inflammation, and inflammation during second lactation with previous inflammation. We identified differentially methylated cytosines (DMCs), differentially methylated regions (DMRs), and some differentially expressed genes (DEGs) for each comparison. The three comparisons shared some DEGs; however, few DMCs and only one DMR were shared. These observations suggest that inflammation is one of several factors affecting epigenetic regulation during successive lactations. Furthermore, the comparison between animals in second lactation with and without inflammation, with no inflammation history during first lactation showed a different pattern compared to the other conditions in this experiment. This indicates that inflammation history plays an important role in determining epigenetic changes. The data presented in this study suggest that lactation rank and previous inflammation history are equally important when explaining mammary tissue gene expression and DNA methylation changes.Abbreviations: RRBS, reduced representation bisulfite sequencing; RT-qPCR, real-time quantitative polymerase chain reaction; MEC, mammary epithelial cells; TSS, transcription start site; TTS, transcription termination site; UTR, untranslated region; SINE, short interspersed nuclear element; LINE, long interspersed nuclear element; CGI, CpG island; DEG, differentially expressed gene; DMC, differentially methylated cytosine; DMR, differentially methylated region; GO term, gene ontology term; MF, molecular function; BP, biological process.

Triptolide induces PANoptosis in macrophages and causes organ injury in mice

Macrophages represent the first lines of innate defense against pathogenic infections and are poised to undergo multiple forms of regulated cell death (RCD) upon infections or toxic stimuli, leading to multiple organ injury. Triptolide, an active compound isolated from Tripterygium wilfordii Hook F., possesses various pharmacological activities including anti-tumor and anti-inflammatory effects, but its applications have been hampered by toxic adverse effects. It remains unknown whether and how triptolide induces different forms of RCD in macrophages. In this study, we showed that triptolide exhibited significant cytotoxicity on cultured macrophages in vitro, which was associated with multiple forms of lytic cell death that could not be fully suppressed by any one specific inhibitor for a single form of RCD. Consistently, triptolide induced the simultaneous activation of pyroptotic, apoptotic and necroptotic hallmarks, which was accompanied by the co-localization of ASC specks respectively with RIPK3 or caspase-8 as well as their interaction with each other, indicating the formation of PANoptosome and thus the induction of PANoptosis. Triptolide-induced PANoptosis was associated with mitochondrial dysfunction and ROS production. PANoptosis was also induced by triptolide in mouse peritoneal macrophages in vivo. Furthermore, triptolide caused kidney and liver injury, which was associated with systemic inflammatory responses and the activation of hallmarks for PANoptosis in vivo. Collectively, our data reveal that triptolide induces PANoptosis in macrophages in vitro and exhibits nephrotoxicity and hepatotoxicity associated with induction of PANoptosis in vivo, suggesting a new avenue to alleviate triptolide's toxicity by harnessing PANoptosis.

Exploring the potential and safety of quantum dots in allergy diagnostics

Biomedical investigations in nanotherapeutics and nanomedicine have recently intensified in pursuit of new therapies with improved efficacy. Quantum dots (QDs) are promising nanomaterials that possess a wide array of advantageous properties, including electronic properties, optical properties, and engineered biocompatibility under physiological conditions. Due to these characteristics, QDs are mainly used for biomedical labeling and theranostic (therapeutic-diagnostic) agents. QDs can be functionalized with ligands to facilitate their interaction with the immune system, specific IgE, and effector cell receptors. However, undesirable side effects such as hypersensitivity and toxicity may occur, requiring further assessment. This review systematically summarizes the potential uses of QDs in the allergy field. An overview of the definition and development of QDs is provided, along with the applications of QDs in allergy studies, including the detection of allergen-specific IgE (sIgE), food allergens, and sIgE in cellular tests. The potential treatment of allergies with QDs is also described, highlighting the toxicity and biocompatibility of these nanodevices. Finally, we discuss the current findings on the immunotoxicity of QDs. Several favorable points regarding the use of QDs for allergy diagnosis and treatment are noted.

Polyethyleneimine-coated MXene quantum dots improve cotton tolerance to Verticillium dahliae by maintaining ROS homeostasis

Verticillium dahliae is a soil-borne hemibiotrophic fungal pathogen that threatens cotton production worldwide. In this study, we assemble the genomes of two V. dahliae isolates: the more virulence and defoliating isolate V991 and nondefoliating isolate 1cd3-2. Transcriptome and comparative genomics analyses show that genes associated with pathogen virulence are mostly induced at the late stage of infection (Stage II), accompanied by a burst of reactive oxygen species (ROS), with upregulation of more genes involved in defense response in cotton. We identify the V991-specific virulence gene SP3 that is highly expressed during the infection Stage II. V. dahliae SP3 knock-out strain shows attenuated virulence and triggers less ROS production in cotton plants. To control the disease, we employ polyethyleneimine-coated MXene quantum dots (PEI-MQDs) that possess the ability to remove ROS. Cotton seedlings treated with PEI-MQDs are capable of maintaining ROS homeostasis with enhanced peroxidase, catalase, and glutathione peroxidase activities and exhibit improved tolerance to V. dahliae. These results suggest that V. dahliae trigger ROS production to promote infection and scavenging ROS is an effective way to manage this disease. This study reveals a virulence mechanism of V. dahliae and provides a means for V. dahliae resistance that benefits cotton production.

Unraveling temporal and spatial biomarkers of epithelial-mesenchymal transition in colorectal cancer: insights into the crucial role of immunosuppressive cells

The occurrence and progression of tumors can be established through a complex interplay among tumor cells undergoing epithelial-mesenchymal transition (EMT), invasive factors and immune cells. In this study, we employed single-cell RNA sequencing (scRNA-seq) and spatially resolved transcriptomics (ST) to evaluate the pseudotime trajectory and spatial interactive relationship between EMT-invasive malignant tumors and immune cells in primary colorectal cancer (CRC) tissues at different stages (stage I/II and stage III with tumor deposit). Our research characterized the spatiotemporal relationship among different invasive tumor programs by constructing pseudotime endpoint-EMT-invasion tumor programs (EMTPs) located at the edge of ST, utilizing evolution trajectory analysis integrated with EMT-invasion genes. Strikingly, the invasive and expansive process of tumors undergoes remarkable spatial reprogramming of regulatory and immunosuppressive cells, such as myeloid-derived suppressor cells (MDSCs), tumor-associated macrophages (TAMs), regulatory T cells (Treg), and exhausted T cells (Tex). These EMTP-adjacent cell are linked to EMT-related invasion genes, especially the C-X-C motif ligand 1 (CXCL1) and CXCL8 genes that are important for CRC prognosis. Interestingly, the EMTPs in stage I mainly produce an inflammatory margin invasive niche, while the EMTPs in stage III tissues likely produce a hypoxic pre-invasive niche. Our data demonstrate the crucial role of regulatory and immunosuppressive cells in tumor formation and progression of CRC. This study provides a framework to delineate the spatiotemporal invasive niche in CRC samples.

Anti-inflammatory effect and mechanism of catalpol in various inflammatory diseases

Catalpol is a kind of iridoid glucoside, widely found in a variety of plants, mostly extracted from the rhizome of the traditional medicinal herb rehmanniae. It has various biological activities such as anti-inflammatory, antioxidant, and antitumor. The anti-inflammatory effects of catalpol have been demonstrated in a variety of diseases, such as neurological diseases, atherosclerosis, renal diseases, respiratory diseases, digestive diseases, bone and joint diseases, eye diseases, and periodontitis. The purpose of this review is to summarize the existing literature on the anti-inflammatory effects of catalpol in a variety of inflammatory diseases over the last decade and to focus on the anti-inflammatory mechanisms of catalpol.

Genome-Wide CRISPR/Cas9 Screening Identifies That Mitochondrial Solute Carrier SLC25A23 Attenuates Type I IFN Antiviral Immunity via Interfering with MAVS Aggregation

Activation of the mitochondrial antiviral signaling (MAVS) adaptor, also known as IPS-1, VISA, or Cardif, is crucial for antiviral immunity in retinoic acid-inducible gene I (RIG-I)-like receptor signaling. Upon interacting with RIG-I, MAVS undergoes K63-linked polyubiquitination by the E3 ligase Trim31, and subsequently aggregates to activate downstream signaling effectors. However, the molecular mechanisms that modulate MAVS activation are not yet fully understood. In this study, the mitochondrial solute carrier SLC25A23 was found to attenuate type I IFN antiviral immunity using genome-wide CRISPR/Cas9 screening. SLC25A23 interacts with Trim31, interfering with its binding of Trim31 to MAVS. Indeed, SLC25A23 downregulation was found to increase K63-linked polyubiquitination and subsequent aggregation of MAVS, which promoted type I IFN production upon RNA virus infection. Consistently, mice with SLC25A23 knockdown were more resistant to RNA virus infection in vivo. These findings establish SLC25A23 as a novel regulator of MAVS posttranslational modifications and of type I antiviral immunity.

Autophagy and LC3-associated phagocytosis contribute negatively to the killing capability of THP-1-derived macrophages against Candida albicans at the mid-stage

In innate immunity, macrophages play critical roles in defending against pathogens via the lysosomal degradation function of autophagy. Two distinct autophagy pathways have been identified in decades: canonical autophagy (referred to as autophagy) and LC3-associated phagocytosis (LAP). Since several conflicting findings about the anti-Candida capability of autophagy (or LAP) have been reported, they serve as the foe or friend for Candida survival is still unclearly. The current study showed that the fungicidal process of THP-1-derived macrophages (THP-1-MФ) against Candida albicans is divided into three stages as follows, the early stage (the first 12 h, increasing in the killing capability), the mid-stage (12-24 h, no change in killing capability), and the late stage (24-48 h, decreasing of the killing capability). Autophagic protein LC3B-II reached the peak in THP-1-MФ after 24 h inoculated either with C.albicans or whole glucan particles (WGP). Thus, both anti-Candida roles of autophagy and the LAP pathway have been detected at the mid-stage. For autophagy, after 24 h inoculation with C.albicans, ULK1 increased, but p-ATG13(s318) decreased obviously in THP-1-MФ, and the killing assay showed that autophagy is unhelpful for Candida killing capability. For the LAP pathway, Rubicon and ROS raised significantly in THP-1-MФ after 24 h inoculated with C.albicans; each inhibition would sharply cut down the LC3B-II accumulation, which indicated that LAP had been induced. However, mCherry-GFP-LC3 fluorescent assay exhibited that LAP phago-lysosomal fusion has been blocked, and Rubicon knockdown facilitated the Candida killing activity. These data indicated that autophagy presented as redundant to Candida defense, and LAP phago-lysosomal fusion obstruction impairs the Candida killing capability of THP-1-MФ at the mid-stage. That may explain the no change in Candida killing capability at the mid-stage.

Virus-induced lncRNA-BTX allows viral replication by regulating intracellular translocation of DHX9 and ILF3 to induce innate escape

The roles of long noncoding RNA (lncRNA) and RNA-binding proteins (RBPs) in antiviral innate response warrant further investigation. Here, we identify an lncRNA, termed lncRNA-BTX (between Tbk1 and Xpot), which is upregulated upon viral infection via an IRF3-type I interferon-independent pathway, promoting viral innate immune escape. Deletion of lncRNA-BTX in cells or mice significantly reduces viral load in vitro or in vivo, respectively. Mechanistically, lncRNA-BTX strengthens the interactions between DHX9 or ILF3 (two RBPs that have opposite functions in regulating the replication of RNA virus) and their respective partner, JMJD6 or ILF2, which regulates intracellular translocations of DHX9 and ILF3 from the nucleus to the cytoplasm. Put simply, lncRNA-BTX facilitates DHX9's return to the cytoplasm and retains ILF3 within the nucleus, promoting viral replication. This work unveils a strategy developed by the virus to bypass host innate immunity, thus providing a potential target for antiviral therapeutics.

Enzymolysis-based RNA pull-down identifies YTHDC2 as an inhibitor of antiviral innate response

The innate immune response must be terminated in a timely manner at the late stage of infection to prevent unwanted inflammation. The role of m6A-modified RNAs and their binding partners in this process is not well known. Here, we develop an enzymolysis-based RNA pull-down (eRP) method that utilizes the immunoglobulin G-degrading enzyme of Streptococcus pyogenes (IdeS) to fish out m6A-modified RNA-associated proteins. We apply eRP to capture the methylated single-stranded RNA (ssRNA) probe-associated proteins and identify YT521-B homology domain-containing 2 (YTHDC2) as the m6A-modified interferon β (IFN-β) mRNA-binding protein. YTHDC2, induced in macrophages at the late stage of virus infection, recruits IFN-stimulated exonuclease ISG20 (IFN-stimulated exonuclease gene 20) to degrade IFN-β mRNA, consequently inhibiting antiviral innate immune response. In vitro and in vivo deficiency of YTHDC2 increases IFN-β production at the late stage of viral infection. Our findings establish an eRP method to effectively identify RNA-protein interactions and add mechanistic insight to the termination of innate response for maintaining homeostasis.

Progress in understanding the role of cGAS-STING pathway associated with programmed cell death in intervertebral disc degeneration

Nucleus pulposus (NP) inflammatory response can induce intervertebral disc degeneration (IVDD) by causing anabolic and catabolic disequilibrium of the extracellular matrix (ECM). This process is accompanied by the production of endogenous DNAs, then detectable by the DNA sensor cyclic GMP-AMP synthase (cGAS). cGAS recognizes these DNAs and activates the downstream adaptor protein, a stimulator of interferon genes (STING), initiating a cascade of inflammation responses through various cytokines. This evidence implies a crucial role of the cGAS-STING signaling pathway in IVDD. Additionally, it is suggested that this pathway could modulate IVDD progression by regulating apoptosis, autophagy, and pyroptosis. However, a detailed understanding of the role of cGAS-STING pathway in IVDD is still lacking. This review provides a comprehensive summary of recent advances in our understanding of the role of the cGAS-STING pathway in modulating inflammatory response in IVDD. We delve into the connection between the cGAS-STING axis and apoptosis, autophagy, and pyroptosis in IVDD. Furthermore, we discuss the therapeutic potential of targeting the cGAS-STING signaling pathway in IVDD treatment. Overall, this review aims to provide a foundation for future directions in IVDD treatment strategies.

Multimodal Imaging-Guided Strategy for Developing 177Lu-Labeled Metal-Organic Framework Nanomedicine with Potential in Cancer Therapy

Nano-metal-organic frameworks (nano-MOFs) labeled with radionuclides have shown great potential in the anticancer field. In this work, we proposed to combine fluorescence imaging (FI) with nuclear imaging to systematically evaluate the tumor inhibition of new nanomedicines from living cancer cells to the whole body, guiding the design and application of a high-performance anticancer radiopharmaceutical to glioma. An Fe-based nano-MOF vector, MIL-101(Fe)/PEG-FA, was decorated with fluorescent sulfo-cyanine7 (Cy7) to investigate the binding affinity of the targeting nanocarriers toward glioma cells in vitro, as well as possible administration modes for in vivo cancer therapy. Then, lutetium-177 (177Lu)-labeled MIL-101(Fe)/PEG-FA was prepared for high-sensitive imaging and targeted radiotherapy of glioma in vivo. It has been demonstrated that the obtained 177Lu-labeled MIL-101(Fe)/PEG-FA can work as a complementary probe to rectify the cancer binding affinity of the prepared nanocarrier given by fluorescence imaging, providing more precise biodistribution information. Besides, 177Lu-labeled MIL-101(Fe)/PEG-FA has excellent antitumor effect, leading to cell proliferation inhibition, upregulation of intracellular reactive oxygen species, tumor growth suppression, and immune response-related protein and cytokine upregulation. This work reveals that optical imaging and nuclear imaging can work complementarily as multimodal imaging in the design and evaluation of anticancer nanomedicine, offering a MIL-101(Fe)/PEG-FA-based pharmaceutical with potential in tumor endoradiotherapy.

Integration of Protein Nanocage with CpG Motifs: A Virus-Mimicked Core-Shell Nanostructure to Ignite Antitumor Immunity

The tumor microenvironment typically possesses immunosuppressive properties that hinder the effectiveness of antitumor immune responses, even in the context of immunotherapies. However, it is observed that pathogenic microorganisms can trigger strong immune responses during infection, offering a potential means to counteract the immunosuppressive environment of tumors. In this study, a protein nanocage called CpG@HBc nanocages (NCs) is developed, which mimics the structure of the hepatitis B virus and combines with an immunostimulatory component known as cytosine phosphoguanosine oligonucleotide (CpG). By delivering these immunostimulatory agents, CpG@HBc NCs are able to effectively reverse the suppressive tumor microenvironment, resulting in the inhibition of poorly immunogenic tumors in mice. Through high-dimensional mass cytometry (CyTOF) analysis, remarkable alterations in immune responses is observed induced by CpG@HBc. Treatment with immunogenic CpG@HBc NCs, along with co-injection of an OX40 agonist, sensitized colorectal cancer tumors to T cell immune responses, resulting in significant impairment of tumor growth and robust immune activation. Furthermore, CpG@HBc NCs induced long-term antitumor immunological memory, protecting tumor-cured mice from tumor rechallenge. Overall, these findings highlight the potential of a virus-inspired protein nanocage to mimic anti-viral immunity and offer a unique therapeutic approach for cancer immunotherapy.

Lysine methyltransferase SMYD2 inhibits antiviral innate immunity by promoting IRF3 dephosphorylation

Phosphorylation of IRF3 is critical to induce type I interferon (IFN-I) production in antiviral innate response. Here we report that lysine methyltransferase SMYD2 inhibits the expressions of IFN-I and proinflammatory cytokines in macrophages upon viral infections. The Smyd2-deficient mice are more resistant to viral infection by producing more IFN-I and proinflammatory cytokines. Mechanistically, SMYD2 inhibits IRF3 phosphorylation in macrophages in response to viral infection independent of its methyltransferase activity. We found that SMYD2 interacts with the DNA-binding domain (DBD) and IRF association domain (IAD) domains of IRF3 by its insertion SET domain (SETi) and could recruit phosphatase PP1α to enhance its interaction with IRF3, which leads to decreased phosphorylation of IRF3 in the antiviral innate response. Our study identifies SMYD2 as a negative regulator of IFN-I production against virus infection. The new way of regulating IRF3 phosphorylation will provide insight into the understanding of IFN-I production in the innate response and possible intervention of the related immune disorders.

Bacterial outer membrane vesicles in cancer: Biogenesis, pathogenesis, and clinical application

Outer membrane vesicles (OMVs) are spherical, nano-sized particles of bilayer lipid structure secreted by Gram-negative bacteria. They contain a series of cargos from bacteria and are important messengers for communication between bacteria and their environment. OMVs play multiple roles in bacterial survival and adaptation and can affect host physiological functions and disease development by acting on host cell membranes and altering host cell signaling pathways. This paper summarizes the mechanisms of OMV genesis and the multiple roles of OMVs in the tumor microenvironment. Also, this paper discusses the prospects of OMVs for a wide range of applications in drug delivery, tumor diagnosis, and therapy.

Siglecs family used by pathogens for immune escape may engaged in immune tolerance in pregnancy

The Siglecs family is a group of type I sialic acid-binding immunoglobulin-like receptors that regulate cellular signaling by recognizing sialic acid epitopes. Siglecs are predominantly expressed on the surface of leukocytes, where they play a crucial role in regulating immune activity. Pathogens can exploit inhibitory Siglecs by utilizing their sialic acid components to promote invasion or suppress immune functions, facilitating immune evasion. The establishing of an immune-balanced maternal-fetal interface microenvironment is essential for a successful pregnancy. Dysfunctional immune cells may lead to adverse pregnancy outcomes. Siglecs are important for inducing a phenotypic switch in leukocytes at the maternal-fetal interface toward a less toxic and more tolerant phenotype. Recent discoveries regarding Siglecs in the reproductive system have drawn further attention to their potential roles in reproduction. In this review, we primarily discuss the latest advances in understanding the impact of Siglecs as immune regulators on infections and pregnancy.

XAF1 promotes anti-RNA virus immune responses by regulating chromatin accessibility

A rapid induction of antiviral genes is critical for eliminating viruses, which requires activated transcription factors and opened chromatins to initiate transcription. However, it remains elusive how the accessibility of specific chromatin is regulated during infection. Here, we found that XAF1 functioned as an epigenetic regulator that liberated repressed chromatin after infection. Upon RNA virus infection, MAVS recruited XAF1 and TBK1. TBK1 phosphorylated XAF1 at serine-252 and promoted its nuclear translocation. XAF1 then interacted with TRIM28 with the guidance of IRF1 to the specific locus of antiviral genes. XAF1 de-SUMOylated TRIM28 through its PHD domain, which led to increased accessibility of the chromatin and robust induction of antiviral genes. XAF1-deficient mice were susceptible to RNA virus due to impaired induction of antiviral genes. Together, XAF1 acts as an epigenetic regulator that promotes the opening of chromatin and activation of antiviral immunity by targeting TRIM28 during infection.

Ethanol mediates the interaction between Caenorhabditis elegans and the nematophagous fungus Purpureocillium lavendulum

Accurately recognizing pathogens by the host is vital for initiating appropriate immune response against infecting microorganisms. Caenorhabditis elegans has no known receptor to recognize pathogen-associated molecular pattern. However, recent studies showed that nematodes have a strong specificity for transcriptomes infected by different pathogens, indicating that they can identify different pathogenic microorganisms. However, the mechanism(s) for such specificity remains largely unknown. In this study, we showed that the nematophagous fungus Purpureocillium lavendulum can infect the intestinal tract of the nematode C. elegans and the infection led to the accumulation of reactive oxygen species (ROS) in the infected intestinal tract, which suppressed fungal growth. Co-transcriptional analysis revealed that fungal genes related to anaerobic respiration and ethanol production were up-regulated during infection. Meanwhile, the ethanol dehydrogenase Sodh-1 in C. elegans was also up-regulated. Together, these results suggested that the infecting fungi encounter hypoxia stress in the nematode gut and that ethanol may play a role in the host-pathogen interaction. Ethanol production in vitro during fungal cultivation in hypoxia conditions was confirmed by gas chromatography-mass spectrometry. Direct treatment of C. elegans with ethanol elevated the sodh-1 expression and ROS accumulation while repressing a series of immunity genes that were also repressed during fungal infection. Mutation of sodh-1 in C. elegans blocked ROS accumulation and increased the nematode's susceptibility to fungal infection. Our study revealed a new recognition and antifungal mechanism in C. elegans. The novel mechanism of ethanol-mediated interaction between the fungus and nematode provides new insights into fungal pathogenesis and for developing alternative biocontrol of pathogenic nematodes by nematophagous fungi. IMPORTANCE Nematodes are among the most abundant animals on our planet. Many of them are parasites in animals and plants and cause human and animal health problems as well as agricultural losses. Studying the interaction of nematodes and their microbial pathogens is of great importance for the biocontrol of animal and plant parasitic nematodes. In this study, we found that the model nematode Caenorhabditis elegans can recognize its fungal pathogen, the nematophagous fungus Purpureocillium lavendulum, through fungal-produced ethanol. Then the nematode elevated the reactive oxygen species production in the gut to inhibit fungal growth in an ethanol dehydrogenase-dependent manner. With this mechanism, novel biocontrol strategies may be developed targeting the ethanol receptor or metabolic pathway of nematodes. Meanwhile, as a volatile organic compound, ethanol should be taken seriously as a vector molecule in the microbial-host interaction in nature.

WDR77 inhibits prion-like aggregation of MAVS to limit antiviral innate immune response

RIG-I-MAVS signaling pathway plays a crucial role in defending against pathogen infection and maintaining immune balance. Upon detecting viral RNA, RIG-I triggers the formation of prion-like aggregates of the adaptor protein MAVS, which then activates the innate antiviral immune response. However, the mechanisms that regulate the aggregation of MAVS are not yet fully understood. Here, we identified WDR77 as a MAVS-associated protein, which negatively regulates MAVS aggregation. WDR77 binds to MAVS proline-rich region through its WD2-WD3-WD4 domain and inhibits the formation of prion-like filament of recombinant MAVS in vitro. In response to virus infection, WDR77 is recruited to MAVS to prevent the formation of its prion-like aggregates and thus downregulate RIG-I-MAVS signaling in cells. WDR77 deficiency significantly potentiates the induction of antiviral genes upon negative-strand RNA virus infections, and myeloid-specific Wdr77-deficient mice are more resistant to RNA virus infection. Our findings reveal that WDR77 acts as a negative regulator of the RIG-I-MAVS signaling pathway by inhibiting the prion-like aggregation of MAVS to prevent harmful inflammation.

Edge Length-Programmed Single-Stranded RNA Origami for Predictive Innate Immune Activation and Therapy

Ligands targeting nucleic acid-sensing receptors activate the innate immune system and play a critical role in antiviral and antitumoral therapy. However, ligand design for in situ stability, targeted delivery, and predictive immunogenicity is largely hampered by the sophisticated mechanism of the nucleic acid-sensing process. Here, we utilize single-stranded RNA (ssRNA) origami with precise structural designability as nucleic acid sensor-based ligands to achieve improved biostability, organelle-level targeting, and predictive immunogenicity. The natural ssRNAs self-fold into compact nanoparticles with defined shapes and morphologies and exhibit resistance against RNase digestion in vitro and prolonged retention in macrophage endolysosomes. We find that programming the edge length of ssRNA origami can precisely regulate the degree of macrophage activation via a toll-like receptor-dependent pathway. Further, we demonstrate that the ssRNA origami-based ligand elicits an anti-tumoral immune response of macrophages and neutrophils in the tumor microenvironment and retards tumor growth in the mouse pancreatic tumor model. Our ssRNA origami strategy utilizes structured RNA ligands to achieve predictive immune activation, providing a new solution for nucleic acid sensor-based ligand design and biomedical applications.

Circular and Circulating DNA in Inflammatory Bowel Disease: From Pathogenesis to Potential Molecular Therapies

Inflammatory bowel diseases (IBD), including Crohn's Disease (CD) and Ulcerative Colitis (UC) are chronic multifactorial disorders which affect the gastrointestinal tract with variable extent. Despite extensive research, their etiology and exact pathogenesis are still unknown. Cell-free DNAs (cfDNAs) are defined as any DNA fragments which are free from the origin cell and able to circulate into the bloodstream with or without microvescicles. CfDNAs are now being increasingly studied in different human diseases, like cancer or inflammatory diseases. However, to date it is unclear how IBD etiology is linked to cfDNAs in plasma. Extrachromosomal circular DNA (eccDNA) are non-plasmidic, nuclear, circular and closed DNA molecules found in all eukaryotes tested. CfDNAs appear to play an important role in autoimmune diseases, inflammatory processes, and cancer; recently, interest has also grown in IBD, and their role in the pathogenesis of IBD has been suggested. We now suggest that eccDNAs also play a role in IBD. In this review, we have comprehensively collected available knowledge in literature regarding cfDNA, eccDNA, and structures involving them such as neutrophil extracellular traps and exosomes, and their role in IBD. Finally, we focused on old and novel potential molecular therapies and drug delivery systems, such as nanoparticles, for IBD treatment.

The role of fibromodulin in inflammatory responses and diseases associated with inflammation

Inflammation is an immune response that the host organism eliminates threats from foreign objects or endogenous signals. It plays a key role in the progression, prognosis as well as therapy of diseases. Chronic inflammatory diseases have been regarded as the main cause of death worldwide at present, which greatly affect a vast number of individuals, producing economic and social burdens. Thus, developing drugs targeting inflammation has become necessary and attractive in the world. Currently, accumulating evidence suggests that small leucine-rich proteoglycans (SLRPs) exhibit essential roles in various inflammatory responses by acting as an anti-inflammatory or pro-inflammatory role in different scenarios of diseases. Of particular interest was a well-studied member, termed fibromodulin (FMOD), which has been largely explored in the role of inflammatory responses in inflammatory-related diseases. In this review, particular focus is given to the role of FMOD in inflammatory response including the relationship of FMOD with the complement system and immune cells, as well as the role of FMOD in the diseases associated with inflammation, such as skin wounding healing, osteoarthritis (OA), tendinopathy, atherosclerosis, and heart failure (HF). By conducting this review, we intend to gain insight into the role of FMOD in inflammation, which may open the way for the development of new anti-inflammation drugs in the scenarios of different inflammatory-related diseases.

E3 ligase HECTD3 promotes RNA virus replication and virus-induced inflammation via K33-linked polyubiquitination of PKR

Uncontrolled viral replication and excessive inflammation are the main causes of death in the host infected with virus. Hence inhibition of intracellular viral replication and production of innate cytokines, which are the key strategies of hosts to fight virus infections, need to be finely tuned to eliminate viruses while avoid harmful inflammation. The E3 ligases in regulating virus replication and subsequent innate cytokines production remain to be fully characterized. Here we report that the deficiency of the E3 ubiquitin-protein ligase HECTD3 results in accelerated RNA virus clearance and reduced inflammatory response both in vitro and in vivo. Mechanistically, HECTD3 interacts with dsRNA-dependent protein kinase R (PKR) and mediates Lys33-linkage of PKR, which is the first non-proteolytic ubiquitin modification for PKR. This process disrupts the dimerization and phosphorylation of PKR and subsequent EIF2α activation, which results in the acceleration of virus replication, but promotes the formation of PKR-IKK complex and subsequent inflammatory response. The finding suggests HECTD3 is the potential therapeutic target for simultaneously restraining RNA virus replication and virus-induced inflammation once pharmacologically inhibited.