Herpes simplex virus type 1 (HSV-1) is a prevalent pathogen that can lead to severe diseases, including herpes labialis, keratitis, and encephalitis. The development of novel antiviral therapies is significant due to the limited number of available treatments and the emergence of drug-resistant strains. In this study, a series of aza-fused heterocyclic derivatives were synthesized and evaluated for antiviral efficacy. Compound 5i demonstrated notable antiviral activity in vitro with an EC50 (Effective Concentration 50 %) of 1.95 ± 0.07 μM. This effect was achieved by inhibiting viral replication and targeting viral ICP4 and gD proteins. In addition, the expression of STING and NF-κB signaling pathways was down-regulated, cytokine storm was reduced, and the multi-targeted activity of compound 5i inhibited apoptosis. The high efficacy of compound 5i was demonstrated in a mouse herpes encephalitis model. Infected mice's survival significantly improved, and viral load in brain tissue was substantially reduced in the presence of compound 5i. Furthermore, compound 5i demonstrated favorable safety in preliminary in vivo evaluations, with no adverse effects on major organs observed. In conclusion, the aza-fused heterocyclic derivative 5i has substantial potential as a therapeutic agent for HSV-1 infection, providing a valuable foundation for further drug development and clinical translation.

One of the most well-known viral receptors of the group called named ALRs is IFI16 (interferon-inducible protein 16) that are responsible for responses against viral dsDNA. A pyrin domain (PYD), two HIN domains, a NLS (nuclear localization sequence), and S/T/P repeats region form the structure of IFI16. Five alternatively transcripts have been described (V1, V2, V9, V4 and Vβ) that encode five isoforms (IFI16-iso1, 2, 3, 4 and β) with different structure, localization, and function. Another four transcripts (V3, V5, V6, and V8) and 12 predicted transcripts (VX1-VX7, VX1.1-VX5.1) have also been registered in the Genebank without any structural study. In the present study, we have performed a complete study of the presence of the IFI16 transcripts in a healthy population. All the alternative transcripts described except six of the so-called predicted transcripts were found, furthermore, two new transcripts (V10, V11) were described. The main mechanisms for the regulation of mRNA from IFI16 expression are due to the insertion of non-coding regions and the loss of almost all exons. A total of nine different isoforms were found and the corresponding protein models were constructed to establish the modification of its functionality to form inflammasomes or the binding to viral DNA.

The presence of unexpected DNA in cellular compartments acts as a danger signal that activates immune responses. In mammals, delocalized self-DNA triggers strong inflammatory responses crucial for antiviral immunity and cancer control. In plants, application of exogenous self-DNA increases resistance to pathogens and herbivores. Although several mammalian DNA receptors have been identified with distinct subcellular localizations and mechanisms to discriminate between microbial and mitochondrial DNA, no DNA receptors have been identified in plants. Here, we show current evidence for different potential response mechanisms for DNA perception and consider several hypothetical mechanisms for its recognition in plants. Finally, we provide a potential framework for finding plant self-DNA receptors in the future.

Porcine circovirus type 3 (PCV3) is an emerging pathogen that causes porcine dermatitis and nephropathy syndrome-like symptoms, multisystemic inflammation, and reproductive failure. The PCV3 capsid (Cap) protein interacts with DEAD-box RNA helicase 10 (DDX10), a protein that functions primarily through regulating interferon (IFN)-β production to exert its antiviral activity. However, how the interaction between DDX10 and PCV3 Cap regulates viral replication remains unknown. We used Western blotting, interaction assays, and knockdown analyses to observe impaired PCV3 proliferation in transiently DDX10-overexpressing cells, as indicated by decreased viral protein expression levels and virus production. In contrast, PCV3 replication increased upon small interfering RNA-mediated DDX10 depletion. Furthermore, DDX10 positively regulated IFN-β production and interferon-stimulated gene expression, inhibiting PCV3 replication. Mechanistically, PCV3 Cap co-localized and interacted with DDX10, and the N-terminal nuclear localization signal of PCV3 Cap and the helicase domain of DDX10 were essential for the Cap-DDX10 interaction. Furthermore, PCV3 infection decreases DDX10 expression to antagonize its antiviral activity. These results show that DDX10 antagonizes PCV3 replication by interacting with the PCV3 Cap protein and activating IFN-β responses, which provides important insight into the prevention and control of PCV3 infection.IMPORTANCEClarifying how host factors contribute to infection with PCV3, a newly discovered pathogen associated with multiple clinicopathological signs in swine, helps elucidate viral pathogenesis. The PCV3 Cap protein has been shown to interact with DDX10, a crucial protein that regulates RNA virus replication. Herein, we further demonstrated that DDX10 expression is downregulated in PCV3-infected cells and antagonizes the replication of PCV3 and that DDX10 increases interferon-β and interferon-stimulated gene levels to inhibit PCV3 replication by binding to the PCV3 Cap. In addition, PCV3 infection decreases DDX10 expression to antagonize its antiviral activity. These results reveal a molecular mechanism by which DDX10 antagonizes PCV3 replication by binding to the PCV3 Cap protein and activating IFN signals, thereby providing important targets for preventing and controlling PCV3 infection.

The skin is a complex organ, containing an intricate network of immune cells that are crucial for host barrier function and defence against pathogens. Human papillomavirus (HPV) exclusively infects the skin, and its lifecycle is intimately associated with epithelial cell division and differentiation. There are over 450 HPV types, 12 of which are classified as carcinogenic. The primary focus of this review is the epithelial immune response to HPV infection of the cervix during the initial stages of infection, productive infection, and disease progression. During the early stages of infection, cells are HPV-positive; however, there are no attributable histological changes to the epithelium. The HPV-infected cells have the capacity for innate sensing and signalling through toll-like receptors in response to viral nucleic acids. However, HPV has evolved multiple mechanisms to evade the innate response. During productive infection, all viral antigens are expressed and there are visible histological changes to the epithelium, including koilocytosis. Disease regression is associated with Tbet positive cells in the infected epithelium and the presence of CD4 and CD8 T cells in the lamina propria. Disease progression is associated with the overexpression of the E6 and E7 oncoproteins after integration of viral genomes into the host chromosomal DNA. Histologically, the epithelium is less differentiated, and changes to cells include a higher nuclear-to-cytoplasmic ratio and an increased mitotic index. Immune changes associated with disease progression include increased numbers of cells expressing suppressor molecules, such as FoxP3, Blimp-1, and HMGB1, and myeloid cell infiltrates with an M2-like phenotype. This review highlights the gaps in the understanding of the immune response in HPV-positive cervical neoplasia, and in regression and progression of disease. This knowledge is critical for the development of effective immunotherapies that reliably cause HPV-positive cervical neoplasia to regress.

Microglia are the primary resident immune cells of the central nervous system (CNS) that respond to injury and infections. Being critical to CNS homeostasis, microglia also have been shown to contribute to neurodegenerative diseases and brain cancer. Hence, microglia are regarded as a potential therapeutic target in CNS diseases, resulting in an increased demand for reliable in vitro models. Two human microglia cell lines (HMC3 and C20) are being used in multiple in vitro studies, however, the knowledge of their biological and immunological characteristics remains limited. Our aim was to identify and compare the biological changes in these immortalised immune cells under normal physiological and immunologically challenged conditions. Using high-resolution quantitative mass spectrometry, we have examined in-depth proteomic profiles of non-stimulated and LPS or IFN-γ challenged HMC3 and C20 cells. Our findings reveal that HMC3 cells responded to both treatments through upregulation of immune, metabolic, and antiviral pathways, while C20 cells showed a response associated with mitochondrial and immune activities. Additionally, the secretome analysis demonstrated that both cell lines release IL-6 in response to LPS, while IFN-γ treatment resulted in altered kynurenine pathway activity, highlighting distinct immune and metabolic adaptations.

As an evolutionarily conserved and ubiquitous mechanism of host defense, non-immune cells in vertebrates possess the intrinsic ability to autonomously detect and combat intracellular pathogens. This process, termed cell-autonomous immunity, is distinct from classical innate immunity. In this review, we comprehensively examine the defense mechanisms employed by non-immune cells in response to intracellular pathogen invasion. We provide a detailed analysis of the cytosolic sensors that recognize aberrant nucleic acids, lipopolysaccharide (LPS), and other pathogen-associated molecular patterns (PAMPs). Specifically, we elucidate the molecular mechanisms underlying key signaling pathways, including the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway, the retinoic acid-inducible gene I (RIG-I)-like receptors (RLRs)-mitochondrial antiviral signaling (MAVS) axis, and the guanylate-binding proteins (GBPs)-mediated pathway. Furthermore, we critically evaluate the involvement of these pathways in the pathogenesis of various diseases, including autoimmune disorders, inflammatory conditions, and malignancies, while highlighting their potential as therapeutic targets.

Class A CpG-oligonucleotides (ODNs), a Toll-like receptor 9 (TLR9) agonist, have been applied for treating inflammatory diseases and cancer in preclinical studies and clinical trials. A recent study has reported that class A ODNs can activate the Cyclic GMP-AMP synthase (cGAS) signaling to regulate the inflammatory response in human monocytes. However, it remains unknown whether class A ODNs can activate the cGAS pathways in other cell types, such as fibroblastic reticular cells (FRC), which play critical roles in modulating the immune environments during inflammatory diseases and cancer.

To understand the role of class A ODN in regulating the cGAS signaling in FRC, we treated mouse FRC and human fibroblast with class A ODN, a cGAS agonist (HT-DNA), and combined class A and HT-DNA.

Unexpectedly, we found that class A ODNs suppress the cGAS level and downstream signaling in human and murine FRC. The class A ODN-induced suppression effect on cGAS is limited in FRC, but not other immune cell types, and is independent of TLR9. Performing pulldown assay and Mass spectrum, we found that class A ODNs regulate the cGAS level post translationally by interacting with cGAS and ZNF598, an E3 ubiquitin ligase.

Our data reveal an unrecognized off-target effect of class A ODN on suppressing the cGAS signaling in FRCs, which should be considered when designing class A ODN regimens for inflammatory diseases and cancer.

Sensing of cytosolic, double-stranded (ds) DNA or dsRNA molecules derived from microbial or endogenous sources triggers cell-intrinsic innate immunity, but sensors recognizing both cytosolic dsDNA and dsRNA are sparsely reported. Here we find that full-length human SAMD9 protein directly binds to synthetic or viral dsDNA or dsRNA. Overexpression of SAMD9 from various vertebrate species leads to robust production of interferons and pro-inflammatory cytokines. By contrast, loss of endogenous SAMD9 impairs the interferon responses to cytosolic dsDNA and dsRNA stimulation in multiple cell types and enhances the infectivity of pathogenic dsDNA and dsRNA viruses. Mice lacking Samd9l, the human SAMD9 homolog, show increased viral load and severe clinical manifestations of rotavirus and reovirus infections. Rotavirus-encoded non-structural protein 1 targets SAMD9 for proteasomal degradation. Collectively, our data demonstrate that SAMD9 may serve as a pattern-recognition receptor for cytosolic dsDNA and dsRNA across different domains of life and represents a potential target of viral innate immune evasion.

Orf virus (ORFV) is the type species of Parapoxvirus of the Poxviridae family that induces cutaneous pustular skin lesions in sheep and goats, and causes zoonotic infections in humans. Pattern recognition receptors (PRRs) sense pathogen-associated molecular patterns (PAMPs), leading to the triggering of the innate immune response through multiple signalling pathways involving type I interferons (IFNs). The major PAMPs generated during viral infection are nucleic acids, which are the most important molecules that are recognized by the host. The induction of type l IFNs leads to activation of the Janus kinase (JAK)-signal transducer activator of transcription (STAT) pathway, which results in the induction of hundreds of interferon-stimulated genes (ISGs), many of which encode proteins that have antiviral roles in eliminating virus infection and create an antiviral state. Genetic and functional analyses have revealed that ORFV, as found for other poxviruses, has evolved multiple immunomodulatory genes and strategies that manipulate the innate immune sensing response.

Elongation Factor Tu GTP Binding Domain Containing 2 (EFTUD2), a conserved spliceosomal GTPase, is involved in craniofacial development and various cancers, but its role in lung adenocarcinoma (LUAD) remains unclear.

EFTUD2 expression in LUAD tissues was analyzed using data from TCGA and GEO, and validated by immunohistochemistry, RT-qPCR, and Western blotting. The relationship between EFTUD2 expression and clinical features was examined using Fisher's exact test. Diagnostic and prognostic analyses were performed in R. Hub genes related to EFTUD2 were identified through topological algorithms, and immune infiltration was assessed using CIBERSORT. The cGAS-STING pathway and m6A modification were also analyzed in the TCGA LUAD cohort. Functional assays were conducted to assess EFTUD2's impact on LUAD cell proliferation, cell cycle, invasion, and metastasis, while glycolytic enzyme levels were measured by Western blotting.

EFTUD2 was upregulated in LUAD tissues and cells, correlating with N classification, visceral pleural invasion, intravascular tumor embolism, and cytokeratin-19 fragment antigen 21-1. Sixteen EFTUD2-related hub genes were identified. Higher EFTUD2 expression was linked to altered immune cell infiltration, with increased TumorPurity scores and decreased StromalScore, ImmuneScore, and ESTIMATEScore values. Gene enrichment analyses highlighted EFTUD2's involvement in cell adhesion, immune response. EFTUD2 was strongly associated with the cGAS-STING pathway and m6A modification. EFTUD2 knockdown inhibited LUAD cell proliferation, migration, and tumorigenicity, causing G0/G1 phase cell cycle arrest, and altered glycolytic enzyme expression. These findings may suggest that EFTUD2 positively regulates the progression of LUAD and modulates the glycolytic activity of tumor cells, making it valuable for LUAD treatment and prognosis.

EFTUD2 is a potential diagnostic and prognostic marker for LUAD, associated with immune infiltration, the tumor microenvironment, the cGAS-STING pathway, m6A modification, and glycolysis.

Macrophages can respond to infection or cellular stress by forming inflammasomes or by releasing extracellular traps (ETs) of DNA through METosis. While ETs have been extensively studied in neutrophils, there are fewer studies on METosis. We show that extracellular calcium and LPS enable human monocyte-derived macrophages (hMDM) to release extracellular DNA decorated with myeloperoxidase (MPO) and citrullinated histone, alongside ASC aggregation and IL-1ß maturation, indicating NLRP3 inflammasome activation. Compared with m-CSF differentiated macrophages only gm-CSF differentiated macrophages expressed macrophage elastase (MMP12) and METs released by the latter had significantly more bactericidal activity toward E. coli. Mechanistically, phospholipase C and peptidyl arginine deiminase-2 inhibition attenuate MET release. Interestingly, NLRP3 inflammasome blockade by MCC950 had a significant effect on MET release. Finally, MET release was completely blocked by plasma membrane stabilization by punicalagin. Altogether, we demonstrate that extracellular calcium-activated hMDM extrude DNA, containing citrullinated histones, MPO, MMP12, and ASC specks and released METs kill bacteria independent of hMDM phagocytotic activity. We believe that calcium-activated hMDM adds a physiologically relevant condition to calcium ionophore induced cell death that may be important in autoimmunity.

Nucleic acids from both self- and non-self-sources act as vital danger signals that trigger immune responses. Critical illnesses such as acute respiratory distress syndrome, sepsis, trauma and ischemia lead to the aberrant cytosolic accumulation and massive release of nucleic acids that are detected by antiviral innate immune receptors in the endosome or cytosol. Activation of receptors for deoxyribonucleic acids and ribonucleic acids triggers inflammation, a major contributor to morbidity and mortality in critically ill patients. In the past decade, there has been growing recognition of the therapeutic potential of targeting nucleic acid sensing in critical care. This review summarizes current knowledge of nucleic acid sensing in acute respiratory distress syndrome, sepsis, trauma and ischemia. Given the extensive research on nucleic acid sensing in common pathological conditions like cancer, autoimmune disorders, metabolic disorders and aging, we provide a comprehensive summary of nucleic acid sensing beyond critical illness to offer insights that may inform its role in critical conditions. Additionally, we discuss potential therapeutic strategies that specifically target nucleic acid sensing. By examining nucleic acid sources, sensor activation and function, as well as the impact of regulating these pathways across various acute diseases, we highlight the driving role of nucleic acid sensing in critical illness.

The malaria parasite, Plasmodium falciparum, secretes extracellular vesicles (EVs) to facilitate its growth and to communicate with the external microenvironment, primarily targeting the host's immune cells. How parasitic EVs enter specific immune cell types within the highly heterogeneous pool of immune cells remains largely unknown. Using a combination of imaging flow cytometry and advanced fluorescence analysis, we demonstrated that the route of uptake of parasite-derived EVs differs markedly between host T cells and monocytes. T cells, which are components of the adaptive immune system, internalize parasite-derived EVs mainly through an interaction with the plasma membrane, whereas monocytes, which function in the innate immune system, take up these EVs via endocytosis. The membranal/endocytic balance of EV internalization is driven mostly by the amount of endocytic incorporation. Integrating atomic force microscopy with fluorescence data analysis revealed that internalization depends on the biophysical properties of the cell membrane rather than solely on molecular interactions. In support of this, altering the cholesterol content in the cell membrane tilted the balance in favor of one uptake route over another. Our results provide mechanistic insights into how P. falciparum-derived EVs enter into diverse host cells. This study highlights the sophisticated cell-communication tactics used by the malaria parasite.

IFI16 (interferon-γ-inducible protein 16) is an innate-immune DNA sensor that detects viral dsDNA in the nucleus. It also functions as an antiviral restriction factor, playing a crucial role in regulating the latency/lytic balance of several herpesviruses, including Kaposi's sarcoma-associated herpesvirus (KSHV). We previously demonstrated that IFI16 achieves this by regulating the deposition of H3K9me3 marks on the KSHV genome. Here, we explored whether IFI16 impacts the KSHV latency/lytic balance through additional mechanisms. Our analysis of the IFI16 interactome revealed that IFI16 binds to the class-I HDACs, HDAC1 and HDAC2, and recruits them to the KSHV major latency protein, latency-associated nuclear antigen (LANA). Previous reports have suggested that LANA undergoes lysine acetylation through unknown mechanisms, which results in the loss of its ability to bind to the KSHV transactivator protein (RTA) promoter. However, how the LANA acetylation-deacetylation cycle is orchestrated and what effect this has on KSHV gene expression remains unknown. Here, we demonstrate that LANA, by default, undergoes post-translational acetylation, and during latency, IFI16 interacts with this acetylated LANA and recruits HDAC1/2 to it. This keeps LANA in a deacetylated form, competent in binding and repressing lytic promoters. However, during lytic reactivation, IFI16 is degraded via the proteasomal pathway, leading to the accumulation of acetylated LANA, which cannot bind to the RTA promoter. This results in the de-repression of the RTA and, subsequently, other lytic promoters, driving reactivation. These findings shed new light on the role of IFI16 in KSHV latency and suggest that KSHV utilizes the cellular IFI16-HDAC1/2 interaction to facilitate its latency.

Kaposi's sarcoma-associated herpesvirus (KSHV) is an oncogenic γ-herpesviruses etiologically associated with several human malignancies, including Kaposi's sarcoma, primary effusion B-cell lymphoma, and multicentric Castleman's disease. Understanding the molecular mechanisms governing the establishment and maintenance of latency in γ-herpesviruses is crucial because latency plays a pivotal role in oncogenesis and disease manifestation post-infection. Here, we have elucidated a new mechanism by which IFI16, a previously discovered antiviral restriction factor, is hijacked by KSHV to recruit class-I HDACs on latency-associated nuclear antigen (LANA), resulting in the latter's deacetylation. The acetylation status of LANA is critical for KSHV latency because it governs LANA's binding to the KSHV replication and transcription activator (RTA) promoter, an immediate-early gene crucial for lytic reactivation. Depletion of IFI16 results in the accumulation of acetylated LANA, which is incapable of maintaining latency. These newly discovered interactions between IFI16 and LANA and between IFI16 and HDAC1/2 enhance our understanding of KSHV latency regulations.

Recombinant adeno-associated virus (rAAV) is a widely used viral vector for gene therapy. However, a limitation of AAV-mediated gene therapy is that patients are typically dosed only once. In this study, we investigated the possibility of delivering multiple rounds of AAV through intracerebral injections in the mouse brain, and discovered a dose-dependent modulation of the second administration by the first-round AAV injection in a brain-wide scale. High-dose AAV injection increased chemokines CXCL9 and CXCL10 to recruit parenchymal infiltration of lymphocytes, whereas the blood-brain-barrier was relatively intact. Brain-wide dissection discovered the likely routes of the infiltrated lymphocytes through perivascular space and ventricles. Further analysis revealed that B lymphocytes played a critical role in inhibiting the redose. Choosing the right dosage for the first injection or switching the second AAV to a different serotype provided an effective way to antagonize the first-round AAV inhibition. Together, these results suggest that mammalian brains are not immunoprivileged for AAV infection, but multiple rounds of AAV gene therapy are feasible if designed carefully with proper doses and serotypes.

Porcine circovirus type 3 (PCV3) is an emerging pathogen that causes porcine dermatitis, and reproductive failure. PCV3 Cap interacts with DExD/H-box helicase 36 (DHX36), a protein that functions primarily through regulating interferon (IFN)-β production. However, how the interaction between DHX36 and PCV3 Cap regulates viral replication remains unknown. Herein, we observed impaired PCV3 proliferation after DHX36 overexpression as indicated by decreased Rep protein expression and virus production. In contrast, PCV3 replication increased upon small interfering RNA-mediated DHX36 depletion. Furthermore, DHX36 positively regulated IFN-β production and interferon-stimulated genes (ISGs) expression. Mechanistically, PCV3 Cap interacted with DHX36, and the PCV3 Cap-NLS and DHX36-NTD were essential for the interaction. Furthermore, DHX36 may get degraded because its binding cellular partners became ubiquitinated and then reduced, and PCV3 Cap-(35-100aa) also promoted the degradation of DHX36 through the K48-linked ubiquitination. Taken together, these results show that DHX36 antagonizes PCV3 replication by interacting with PCV3 Cap and activating IFN-β response, which provides important insight on the prevention and controlling of PCV3 infection. IMPORTANCE: Porcine circovirus type 3 (PCV3) is a newly discovered pathogen associated with multiple clinicopathological signs. Clarifying the mechanisms that host factors modulate PCV3 replication helps understanding of the viral pathogenesis. The PCV3 capsid (Cap) protein has been shown to interact with DExD/H-box helicase 36 (DHX36) (Zhou et al., 2022b), a crucial protein that regulates virus replication. Herein, we further demonstrated that DHX36 protein is degraded in PCV3-infected cells and antagonizes the replication of PCV3 and that DHX36 increases interferon-β and interferon-stimulated gene levels by binding to PCV3 Cap. In addition, PCV3 infection could decrease DHX36 expression levels to antagonize its antiviral activity. These results reveal a molecular mechanism by which DHX36 antagonizes PCV3 replication by binding to PCV3 Cap protein and activating IFN signals, thereby providing important targets for preventing and controlling PCV3 infection.

Viruses pose a significant threat to humans by causing numerous infectious and potentially fatal diseases. Understanding how the host's innate immune system recognizes viruses is essential to understanding pathogenesis and ways to control viral infection. Innate immunity also plays a critical role in shaping adaptive immune responses induced by vaccines. Recently developed adjuvants often include nucleic acids that stimulate pattern recognition receptors which are essential components of innate immunity necessary for activating antigen-presentation cells and thereby bridging innate and adaptive immunity. Therefore, understanding viral nucleic acid sensing by cytosolic sensors is essential, as it provides the potential means for developing new vaccine strategies, including effective adjuvants.

Most genetically modified mice have been produced using 129 strain-derived embryonic stem cells. Despite ample backcrosses with other strains, these may retain characteristics for 129 passenger mutations, leading to confounding phenotypes unrelated to targeted genes. Here we show that widely used Ackr1-/-129ES mice have approximately 6 Mb of the 129-derived genome retained adjacently to the Ackr1 locus on chromosome 1, including several characteristic polymorphisms. These most notably affect the expression of PYHIN and Fc-gamma receptor genes in myeloid cells, resulting in the overproduction of IL-1β by activated macrophages and the loss of Fc-gamma receptors on myeloid progenitor cells. Therefore, caution is warranted when interpreting Ackr1-/-129ES mouse phenotypes as being solely due to the ACKR1 deficiency. Our findings call for a careful reevaluation of data from previous studies using Ackr1-/-129ES mice and underscore the limitations and pitfalls inherent to mouse models produced using traditional genetic engineering techniques involving 129 embryonic stem cells.

Herpes simplex virus type 1 (HSV-1) is a DNA virus that infects humans and establishes long-term latency within the host. Throughout its prolonged interaction with the host, HSV-1 evades the innate immune system by encoding its own proteins. Post-translational modifications (PTMs) of these proteins play crucial roles in their function, activity, and interactions with other factors by modifying specific amino acids, thereby enabling a diverse range of protein functions. This review explores the mechanisms and roles of PTMs in HSV-1-encoded proteins, such as phosphorylation, ubiquitination, deamidation, and SUMOylation, during HSV-1 infection and latency. These modifications are essential for suppressing host innate immunity, facilitating viral replication, and elucidating the crosstalk among various post-translational modifications.

This study aimed to elucidate the transcriptomic signatures and dysregulated pathways associated with the autoimmune response in Cd38-/- mice compared to wild-type (WT) mice within the bm12 chronic graft-versus-host disease (cGVHD) lupus model. We conducted bulk RNA sequencing on peritoneal exudate cells (PECs) and spleen cells (SPC) at two and four weeks following adoptive cell transfer. We also analyzed cells from healthy, untreated mice. These analyses revealed a sustained upregulation of a transcriptional profile of purinergic receptors and ectonucleotidases in cGVHD WT PECs, which displayed a coordinated expression with several type I interferon-stimulated genes (ISGs) and with key molecules involved in the cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) signaling pathway, two hallmarks in the lupus pathology. A second purinergic receptor transcriptomic profile, which included P2rx7 and P2rx4, showed a coordinated gene expression of the components of the NLRP3 inflammasome with its potential activators. These processes were transcriptionally less active in cGVHD Cd38-/- PECs than in WT PECs. We have also shown evidence of a distinct enrichment in pathways signatures that define processes such as Ca2+ ion homeostasis, cell division, phagosome, autophagy, senescence, cytokine/cytokine receptor interactions, Th17 and Th1/Th2 cell differentiation in Cd38-/- versus WT samples, which reflected the milder inflammatory and autoimmune response elicited in Cd38-/- mice relative to WT counterparts in response to the allogeneic challenge. Last, we have shown an intense metabolic reprogramming toward oxidative phosphorylation in PECs and SPC from cGVHD WT mice, which may reflect an increased cellular demand for oxygen consumption, in contrast to PECs and SPC from cGVHD Cd38-/- mice, which showed a short-lived metabolic effect at the transcriptomic level. Overall, these findings support the pro-inflammatory and immunomodulatory role of CD38 during the development of the cGVHD-lupus disease.

The skin provides a life-sustaining interface between the body and the external environment. A dynamic communication among immune and non-immune cells in the skin is essential to ensure body homeostasis. Dysregulated cellular communication can lead to the manifestation of inflammatory skin conditions. In this review, we will focus on the following two key frontiers in the skin: innate immune sensors and cell death, as well as their cellular crosstalk in the context of skin homeostasis and inflammation. This review will highlight the recent advancements and mechanisms of how these pathways integrate signals and orchestrate skin immunity, focusing on inflammatory skin diseases and skin infections in mice and humans.

IFNs play a critical role in cancer biology, including impacting tumor cell behavior and instructing the tumor microenvironment (TME). IFNs recently have been shown to reprogram tumor metabolism through distinct mechanisms. Furthermore, IFNs shape the TME by modulating immune cell infiltration and function, contributing to the intricate interaction between the tumor and stromal cells. This review summarizes the effects of IFNs on metabolic reprogramming and their impacts on the function of immune cells within the TME, with a particular focus on the dual roles of IFNs in mediating both anti-tumor and pro-tumor immune responses. Understanding the significance of IFNs-mediated processes aids to advise future therapeutic strategies in cancer treatment.

Epstein-Barr virus (EBV), the first human oncovirus discovered in 1964, has become a focal point in virology, immunology, and oncology because of its unique biological characteristics and significant role in human diseases. As we commemorate the 60th anniversary of EBV's discovery, it is an opportune moment to reflect on the major advancements in our understanding of this complex virus. In this review, we highlight key milestones in EBV research, including its virion structure and life cycle, interactions with the host immune system, association with EBV-associated diseases, and targeted intervention strategies.

Transfection of plasmid DNA (pDNA) encoding target genes is a routine tool in gene function studies and therapeutic applications. However, nucleic acid-sensing-mediated innate immune responses influence multiple intracellular signaling pathways. The stimulator of interferon genes (STING) is a crucial adapter protein for DNA sensors in mammalian cells. In this study, we explored the molecular mechanisms underlying DNA sensing by investigating the relationship between mRNA and protein expression levels and the STING pathway using single-cell analysis. We observed that reporter gene expression was dose-nonlinear after transfection of pDNA in cells with intact DNA-sensing pathways. Moreover, blocking the STING pathway in THP-1 cells significantly downregulated innate immune responses, upregulated exogenous gene expression, and mitigated the effects of innate immune responses on cell and gene function, but did not affect the proportion of reporter protein-positive cells. We elucidated the mechanisms of DNA sensing-induced innate immune response and cell death by analyzing heterozygous cellular responses to DNA transfection and transcriptome changes in positive cells. These findings suggest that the regulation of STING-mediated nucleic acid-sensing pathways is crucial for the accuracy of gene function studies and could enhance the efficacy of gene therapy.

Glioblastoma multiforme (GBM) remains a therapeutic challenge due to its aggressive nature and recurrence. This study establishes a radioresistant GBM cell model through repeated irradiation and observes a cellular senescence-like phenotype in these cells. Comprehensive genomic and transcriptomic analyses identify IFI16 as a central regulator of this phenotype and contributes to radioresistance. IFI16 activates HMOX1 transcription thereby attenuating ferroptosis by reducing lipid peroxidation, ROS production, and intracellular Fe2+ content following irradiation. Furthermore, IFI16 interacts with the transcription factors JUND and SP1 through its pyrin domain, robustly facilitating HMOX1 expression, further inhibiting ferroptosis and enhancing radioresistance in GBM. Notably, glyburide, a sulfonylurea compound, effectively disrupts IFI16 function and enhances ferroptosis and radiosensitivity. By targeting the pyrin domain of IFI16, glyburide emerges as a potential therapeutic agent against GBM radioresistance. These findings underscore the central role of IFI16 in GBM radioresistance and offer promising avenues to improve GBM treatment.

The human body reacts to tissue damage by generating damage-associated molecular patterns (DAMPs) that activate sterile immune responses. To date, little is known about how DAMPs are removed to avoid excessive immune responses. Here, we show that proteasomal dysfunction induces the release of mitochondrial DNA (mtDNA) as a DAMP that activates the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon gene (STING) pathway and is subsequently degraded through the N-degron pathway. In the resolution phase of sterile immune responses, DNA-dependent protein kinase (DNA-PK) senses cytosolic mtDNA and activates N-terminal (Nt-) arginylation by ATE1 R-transferases. The substrates of Nt-arginylation include the molecular chaperone BiP/GRP78 retrotranslocated from the endoplasmic reticulum (ER). R-BiP, the Nt-arginylated species of BiP, is associated with cytosolic mtDNA to accelerate its targeting to autophagic membranes for lysosomal degradation. Thus, cytosolic mtDNA activates the N-degron pathway to facilitate its own degradation and form a negative feedback loop, by which the cell can turn off sterile immune responses at the right time.

The inflammasome is a cytoplasmic multiprotein complex that induces the maturation of the proinflammatory cytokines interleukin-1β (IL-1β) and interleukin-18 (IL-18) or pyroptosis by activating caspases, which play critical roles in regulating inflammation, cell death, and various cellular processes. Multiple studies have shown that the inflammasome is a key regulator of the host defence response against pathogen infections. During the process of pathogenic microbe invasion into host cells, the host's innate immune system recognizes these microbes by activating inflammasomes, triggering inflammatory responses to clear the microbes and initiate immune responses. Moreover, microbial pathogens have evolved various mechanisms to inhibit or evade the activation of inflammasomes. Therefore, we review the interactions between viruses and microbes with inflammasomes during the invasion process, highlight the molecular mechanisms of inflammasome activation induced by microbial pathogen infection, and highlight the corresponding strategies that pathogens employ to evade inflammasome activity. Finally, we also discuss potential therapeutic strategies for the treatment of pathogenic microbial infections via the targeting of inflammasomes and their products.

Aerobic glycolysis is a hallmark of many viral infections, leading to substantial accumulation of lactate. However, the regulatory roles of lactate during viral infections remain poorly understood. Here, we report that human cytomegalovirus (HCMV) infection leverages lactate to induce widespread protein lactylation and promote viral spread. We establish that lactyllysine is enriched in intrinsically disordered regions, regulating viral protein condensates and immune signaling transduction. Dynamic lactylation of immune factors suppresses immunity, a feature we show to be shared for HCMV and herpes simplex virus 1 infections, through regulation of RNA binding protein 14 and interferon-γ-inducible protein 16 (IFI16). K90 lactylation of the viral DNA sensor IFI16 inhibits recruitment of the DNA damage response kinase DNA-PK, preventing IFI16-driven virus gene repression and cytokine induction. Together, we characterize global protein lactylation dynamics during virus infection, finding that virus-induced lactate contributes to its immune evasion through direct inhibition of immune signaling pathways.

The cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) signalling pathway, which recognizes both pathogen DNA and host-derived DNA, has emerged as a crucial component of the innate immune system, having important roles in antimicrobial defence, inflammatory disease, ageing, autoimmunity and cancer. Recent work suggests that the regulation of cGAS-STING signalling is complex and sophisticated. In this Review, we describe recent insights from structural studies that have helped to elucidate the molecular mechanisms of the cGAS-STING signalling cascade and we discuss how the cGAS-STING pathway is regulated by both activating and inhibitory factors. Furthermore, we summarize the newly emerging understanding of crosstalk between cGAS-STING signalling and other signalling pathways and provide examples to highlight the wide variety of cellular processes in which cGAS-STING signalling is involved, including autophagy, metabolism, ageing, inflammation and tumorigenesis.

African swine fever virus (ASFV) is the causative agent of a lethal disease in pigs. Highly virulent strains of ASFV are known to suppress the induction of type I interferons (IFNs), while naturally attenuated strains do not exhibit this capability. Thus, the ability to suppress IFN is assumed to be associated with viral virulence. ASFV genome encodes many proteins capable of disrupting crucial components of host immune response pathways. Notably, these viral proteins interfere with the induction of type I IFNs by targeting various steps of the cGAS-STING signaling pathway. Additionally, certain viral proteins impede the expression of interferon-stimulated genes by interfering with the JAK-STAT pathway. Consequently, ASFV proteins hamper both IFN production and the induction of antiviral responses by IFNs. This review article summarizes the viral proteins responsible for suppressing various steps of the cGAS-STING and JAK-STAT signaling pathways and discusses the potential application of this knowledge to the rational design of a live-attenuated ASFV vaccine.

N-dihydrogalactochitosan (GC) is an immune stimulant/adjuvant. Synthesized from chitosan and galactose, GC is a new chemical entity that significantly enhances the immune-stimulating properties of its parental material, chitosan, making it a promising therapeutic agent. When used in combination with antigenic material, GC stimulates innate and adaptive antitumor and antiviral immunities. However, its mechanism has not been fully investigated. Herein we demonstrate that GC drives type I IFN activation in antigen-presenting cells (APCs). More importantly, GC drives alternative STING pathways, leading to inflammatory cell death that enhances dendritic cell (DC) activation. GC-activated DCs trigger a variety of nucleic acid sensing pattern recognition receptors (PRRs) pathways and IL-1β production via the activation of the inflammasome. In vivo, GC induces a potent response of type I IFNs and upregulates genes associated with STING signaling within the tumor microenvironment (TME). Moreover, intratumoral delivery of GC reduces the numbers of M2-like macrophages and increases M1-like macrophages residing within the TME, while subsequently increasing the number of activated DCs. Our findings demonstrate that GC acts as a multimodal immune stimulant via STING to generate a broad type I IFN response. This uniquely broad response holds therapeutic promise in generating enhanced antitumor and antiviral immunities.

Oncolytic viruses represent a promising class of immunotherapeutic agents for the treatment of malignant tumors. The proposed mechanism of action of various oncolytic viruses has initially been explained by the ability of such viruses to selectively lyse tumor cells without damaging healthy ones. Recently, there have emerged more studies determining the effect of the antiviral immunostimulating mechanisms on the effectiveness of treatment in cancer patients. Stimulation of innate immune cells by an oncolytic virus can initiate an adaptive antitumor immune response, yet at the same time, the antiviral mechanisms of the immune system can limit the spread of the virus, thereby reducing its effectiveness. Thus, the success of the clinical application of the oncolytic viruses directly depends on the three key components: tumor immunosuppression, antiviral responses, and antitumor immune responses. The review presents current data on the influence of pattern recognition receptors on the effectiveness of oncolytic viruses.

Pseudorabies virus (PRV) establishes persistent latent infections by effectively evading the host's antiviral innate immune response. PRV has developed sophisticated strategies to bypass immune surveillance through coevolution with its host. Currently, no effective vaccine exists to prevent or treat infections caused by emerging PRV variants, and the interactions between PRV and the host's innate immune defenses remain incompletely understood. Nevertheless, ongoing research is uncovering insights that may lead to novel treatments and preventive approaches for herpesvirus-related diseases. This review summarizes recent advances in understanding how PRV disrupts key adaptors in immune signaling pathways to evade antiviral immunity. Additionally, we explored the intrinsic cellular defenses that play crucial roles in combating viral invasion. A deeper understanding of the immune evasion strategies of PRV could inform the development of new therapeutic targets and vaccines.

Developments in mRNA/lipid nanoparticle (LNP) technology have advanced the fields of vaccinology and gene therapy, raising questions about immunogenicity. While some mRNA/LNPs generate an adjuvant-like environment in muscle tissue, other mRNA/LNPs are distinct in their capacity for multiple rounds of therapeutic delivery. We evaluate the adjuvancy of components of mRNA/LNPs by phenotyping cellular infiltrate at injection sites, tracking uptake by immune cells, and assessing the inflammatory state. Delivery of 9 common, but chemically distinct, LNPs to muscle revealed two classes of inflammatory gene expression programs: inflammatory (Class A) and noninflammatory (Class B). We find that intramuscular injection with Class A, but not Class B, empty LNPs (eLNPs) induce robust neutrophil infiltration into muscle within 2 h and a diverse myeloid population within 24 h. Single-cell RNA sequencing revealed SM-102-mediated expression of inflammatory chemokines by myeloid infiltrates within muscle 1 day after injection. Surprisingly, we found direct transfection of muscle infiltrating myeloid cells and splenocytes 24 h after intramuscular mRNA/LNP administration. Transfected myeloid cells within the muscle exhibit an activated phenotype 24 h after injection. Similarly, directly transfected splenic lymphocytes and dendritic cells (DCs) are differentially activated by Class A or Class B containing mRNA/LNP. Within the splenic DC compartment, type II conventional DCs (cDC2s) are directly transfected and activated by Class A mRNA/LNP. Together, we show that mRNA and LNPs work synergistically to provide the necessary innate immune stimuli required for effective vaccination. Importantly, this work provides a design framework for vaccines and therapeutics alike.

Interferon (IFN)-γ inducible protein 16 (IFI16), a key DNA sensor, triggers downstream STING-dependent type I interferon (IFN-I) production and antiviral immunity. However, how the IFI16-STING signaling pathway is regulated by EMCV infection is still not well elucidated. In this study, we investigated the interaction between IFI16 and EMCV. Results indicated EMCV infection suppressed IFI16 expression in A549 cells. This study reveals that IFI16 plays an active role in combating EMCV. Screening viral proteins in conjunction with IFI16, we found that the EMCV VP2 protein hinders the antiviral response mediated by IFI16 by causing degradation of the IFI16 protein via the caspase-dependent apoptosis pathway. Our study communicates the antiviral role of the IFI16-STING pathway during EMCV infection. Importantly, this study unveils the novel mechanism by which VP2 counteracts the innate immune signaling activated by foreign DNA.