Lysine lactylation is a crucial posttranslational modification (PTM) that regulates protein function. Here, this study revealed that L-lactic acid promotes host immune response and inhibits viral infection by inducing Interferon Regulatory Factor 9 (IRF9) L-lactylation. We first found L-lactylation modification (L-Kla) of IRF9 mediated by AARS 1. Further studies demonstrated that IRF9 L-lactylation potentiates type I interferon (IFN-I) signaling by promoting IRF9-STAT2 interaction, thereby boosting antiviral immune response. Intriguingly, L-lactic acid exhibits dual effects on viral infection: L-lactic acid exhibits antiviral effects at physiological and moderately elevated levels but proviral effects at high levels. Furthermore, we found that the viruses can achieve immune evasion by promoting SIRT1-mediated delactylation of IRF9. Interestingly, we uncovered that metformin promotes IRF9 L-lactylation by both accumulating lactic acid and disrupting virus-induced IRF9-SIRT1 interaction. These findings renew the understanding of the roles of lactic acid in antiviral immune response and determine metformin's immunomodulatory effects on antiviral immunity through regulating IRF9 L-lactylation.

Glycolysis is a central metabolic pathway that converts glucose into pyruvate. Although pyruvate has been well documented to be a key and terminal metabolite of glycolysis with both energetic and biosynthetic roles, its non-metabolic functions remain unexplored. Here, we report a pyruvate-mediated protein post-translational modification (PTM), protein pyruvylation. We reveal that high glucose-upregulated glycolysis promotes signal transducer and activator of transcription 1 (STAT1) pyruvylation at Lys201 (K201), which blocks STAT1 and signal transducer and activator of transcription 2 (STAT2) interaction, thus suppressing type I interferon (IFN-I) signaling and antiviral immune activity. Consequently, STAT1-K201R knockin mice exhibit enhanced IFN-I antiviral immunity. Importantly, high glucose promotes STAT1 pyruvylation and attenuates immune response to either virus infection or IFN-I treatment in humans. This study identifies the protein pyruvylation modification, reveals a non-metabolic function of the metabolite pyruvate, and provides insights into how high glucose impairs IFN-I antiviral immunity through pyruvate, offering strategies to improve IFN-I immune activity for both preventing and treating viral infections.

Glycosylphosphatidylinositol-specific phospholipase D1 (GPLD1) is traditionally known as a secreted enzyme that sheds glycosylphosphatidylinositol (GPI)-anchored proteins. Emerging evidence suggests its involvement in immune modulation. In this study, we report a non-canonical intracellular function of GPLD1 in potentiating IFN-I-mediated antiviral signaling. Mechanistically, GPLD1 physically interacts with signal transducer and activator of transcription 2 (STAT2) and competitively blocks its interaction with protein-tyrosine phosphatase 1B (PTP1B), a bona fide phosphatase that directly dephosphorylates STAT2 at Tyr690. By shielding STAT2 from PTP1B-mediated dephosphorylation, GPLD1 sustains STAT2 phosphorylation and facilitates time-dependent STAT2 nuclear translocation, thereby amplifying interferon-stimulated gene (ISG) expression and antiviral responses. Collectively, we identify a novel molecular mechanism by which GPLD1 regulates the IFN-I signaling pathway, providing a potential therapeutic target for the development of future antiviral strategies.

Viperin is considered as an antiviral protein known to directly target a variety of viruses. However, whether and how Viperin affects virus infection by targeting intracellular immune signaling remain unexplored. Here, we reveal that Viperin inhibits type-I interferon (IFN-I) antiviral immune signaling by degrading STAT1. We found that IFN-I upregulates the ubiquitin E3 ligase ITCH to degrade UBR5, while Viperin subsequently recruits another ubiquitin E3 ligase UBE4A to promote STAT1 ubiquitination and degradation to attenuate IFN-I signaling. Moreover, the multifunctional interfering peptide VS-IP1 can block Viperin-mediated STAT1 degradation, thus enhancing IFN-I antiviral immune function. This study reveals that Viperin is a suppressor of IFN-I immune signaling, which could renew understanding of the biological function of Viperin, and provide a strategy for enhancing clinical IFN-I therapeutic efficacy.

EV71-encoded 2A protease (2Apro) plays an important regulatory role in EV71 infection and replication. EV71-2Apro can help the viral immune escape by inhibiting host proteins, thereby disrupting the host antiviral immune response. However, the mechanism by which 2Apro proteins are regulated in host cells remains largely unknown. In this study, we identified USP21 that promotes EV71 infection. We discovered that USP21 downregulated K48-linked polyubiquitination of EV71-2Apro and stabilized 2Apro, ultimately promoting EV71 infection. Furthermore, the small-molecule inhibitor, BAY-805, reduced 2Apro levels and inhibited EV71 infection both in vivo and in vitro. Importantly, we found that the expression level of USP21 was positively correlated with the severity of EV71 infection. This study reveals the crucial regulatory role of USP21 in EV71 infection and provides a potential target for the treatment of EV71 infection.

While randomized clinical trials of stress ulcer prophylaxis (SUP) have generally shown no overall benefit, subgroup analyses suggest the benefit or harm of SUP in specific patients, indicating heterogeneity of treatment effects (HTE). Understanding HTE is crucial for tailoring SUP to individual treatment. This cohort study included patients admitted to intensive care unit (ICU) with at least one risk factor for clinically important gastrointestinal bleeding (GIB). The primary exposure was the use of SUP within 48 h after ICU entry; the primary outcome was 28-day mortality. We employed conventional subgroup analysis, risk-based analysis, and effect-based analysis to explore the HTE of SUP. A total of 25,475 patients were included, of whom 6199 (24.3

Aim/Background Ovarian Cancer (OC) accounts for the highest number of deaths among gynecological cancers. Our research is focused on investigating the therapeutic potential and the fundamental mechanism by which miR-142-5p exerts its effects in the treatment of OC. Materials and Methods The GSE53829 and GSE83693 data sets were collected for targeted miRNA identification. RT-qPCR was conducted to evaluate the expression levels of miRNA, N-cadherin, ZO-1, Claudin-1, E-cadherin, and DNMT1 mRNA expressions. Additionally, the protein expressions of these mentioned molecules were quantified using western blot analysis. The invasion and migratory abilities of OC cells were assessed through transwell and wound healing assays. Additionally, the possible interaction between miR-142-5p and DNMT1 was identified and confirmed using the Targetscan database in conjunction with a luciferase assay. Results The mRNA levels of miR-142-5p showed a notable reduction in both OC cell lines and metastatic tumors, as compared to their counterparts of normal ovarian cancer cells and non-metastatic tumors, respectively. Besides, the inhibition or overexpression of miR-142-5p had a significant impact on the migration, invasion ability, and Epithelial-Mesenchymal Transition (EMT) process of OC cells. The levels of DNMT1 were significantly increased in metastatic tumors and were notably affected by the expression of miR-142-5p. Moreover, interaction between DNMT1 mRNA and miR-142-5p was confirmed, and the knockdown of DNMT1 effectively counteracted the significant reversal in OC cell migration, invasion, and EMT caused by miR-142-5p suppression. Conclusion The role of miR-142-5p on OC metastasis is attributed to its ability to suppress EMT through DNMT1, indicating the promising therapeutic potential of miR-142-5p in the treatment of OC.

BACKGROUND:The potential relationship between oral microbiota (OM) and Alzheimer's disease (AD) is increasingly recognized, but the exact causal relationship between them remains uncertain. This study aims to reveal the causal relationship between OM and AD. METHODS:A two-sample Mendelian randomization (MR) approach was employed to examine the association between 594 OM exposures and AD outcomes. Effect estimates were derived from external genome-wide association study (GWAS) summary statistics, primarily utilizing inverse-variance weighted (IVW) analysis. Sensitivity analyses were conducted to assess the robustness of the findings. In addition, we genetically mapped SNPs corresponding to OM in the MR analysis to identify genes that may link OM to AD. RESULTS:A total of 48 OM exposures exhibited statistically significant associations with AD outcomes (p ≤ 0.05). Of these, 30 were identified at the genus level, 12 at the species level, and six at the family level. Genetic function analyses indicated that OM-related genes are closely linked to the regulation of neurobiological functions, supporting a potential role for OM in the pathogenesis of AD. CONCLUSION:The findings presented here provide genetic evidence for a causal relationship between OM and AD, offering insights that may guide the future development of prevention and treatment strategies targeting OM in the context of AD.

Aging changes the protein activity status to affect the body’s functions. However, how aging regulates protein posttranslational modifications (PTMs) to modulate the antiviral defense ability of the body remains unclear. Here, we found that aging promotes STAT1 β-hydroxybutyrylation (Kbhb) at Lys592, which inhibits the interaction between STAT1 and type-I interferon (IFN-I) receptor 2 (IFNAR2), thereby attenuating IFN-I-mediated antiviral defense activity. Additionally, we discovered that a small molecule from a plant source, hydroxy camptothecine, can effectively reduce the level of STAT1 Kbhb, thus increasing antiviral defense ability in vivo. Further studies revealed that STAT1 O-GlcNAc modifications at Thr699 block CBP-induced STAT1 Kbhb. Importantly, fructose can improve IFN-I antiviral defense activity by orchestrating STAT1 O-GlcNAc and Kbhb modifications. This study reveals the significance of the switch between STAT1 Kbhb and O-GlcNAc modifications in regulating IFN-I antiviral immunity during aging and provides potential strategies to improve the body’s antiviral defense ability in elderly individuals.

DNA-RNA hybrids triggered by double-strand breaks (DSBs) are crucial intermediates during DSB repair, and their timely resolution requires numbers of RNA helicases, including DEAD box 1 (DDX1). However, how these helicases are recruited to DSB-induced hybrids in time remains largely unclear. Here, we revealed that squamous cell carcinoma antigen recognized by T cells 3 (SART3) promotes DDX1 binding to DNA-RNA hybrids at DSBs for optimal homologous recombination (HR) repair. SART3 itself associates with DNA-RNA hybrids and PAR chains and accumulates at DSBs in both PARylation- and DNA-RNA hybrids-dependent fashion. SART3 also associates with DDX1 and is necessary for DDX1 enrichment at DSBs. The defective SART3-DDX1 association observed in cells expressing the cancer-associated variant SART3-R836W impairs not only the accumulation of DDX1, but also hybrid removal and HR efficiency. Moreover, SART3 promotes DNA end resection through enhancing USP15-BARD1 association and BRCA1-BARD1 retention. Together, our study reveals an role of SART3 in DSB repair, rendering SART3 a promising target for cancer therapy.

Bilirubin metabolism crucially maintains normal liver function, but whether it contributes to antiviral immunity remains unknown. Here, we reveal that the liver bilirubin metabolic pathway facilitates antiviral innate immunity of the body. We discovered that viral infection upregulates uridine diphosphate glucuronosyltransferase 1A1 (UGT1A1) expression in the liver, which in turn stabilizes IRF3 proteins to promote type I interferon (IFN-I) production. Moreover, we found that serum unconjugated bilirubin (UCB), a unique physiological substrate of UGT1A1, can competitively inhibit the binding of IFN-I to IFN-I receptor 2 (IFNAR2), thus attenuating IFN-I-induced antiviral signaling of the body. Accordingly, effective bilirubin metabolism in the liver promotes antiviral immunity of the body by specifically employing liver UGT1A1-mediated enhancement of IFN-I production and reducing serum bilirubin-mediated inhibition of IFN-I signaling. This study uncovers the significance of bilirubin metabolism in antiviral innate immunity and demonstrates that conventional IFN-I therapy is less efficient for patients with hepatitis B virus (HBV) with high levels of bilirubin.

Anti-melanoma differentiation-associated protein 5 antibody positive dermatomyositis (MDA5+ DM) is an autoimmune disease related to rapidly progressive interstitial lung disease (RPILD) with high mortality. However, the pathogenesis of MDA5+ DM with RPILD remains unclear. We aimed to explore the peripheral immune landscape of MDA5+ DM with RPILD using single-cell RNA sequencing (scRNA-seq). We performed scRNA-seq of peripheral blood mononuclear cells (PBMCs) from MDA5+ DM with RPILD (n = 4), MDA5+ DM with ILD (non-RPILD, n = 3), and healthy controls (HCs, n = 3). The proportion of CD14+ monocytes increased, but the proportion of natural killer cells, CD4+ T cells and CD8+ T cells decreased in MDA5+ DM with RPILD compared with HCs. Obvious antiviral response was the main feature of MDA5+ DM with RPILD, and the expression of several interferon-stimulated genes (ISGs) related to RIG-I pathway increased, including IRF7, DDX60, IFI27 and IFI6. However, this antiviral response was not significant in MDA5+ DM with ILD. In addition, multiple immune pathways were downregulated in MDA5+ DM with RPILD, including antigen processing and presentation, translation initiation, mRNA splicing, and activation of T and B cells. Cell communication analysis revealed that multiple signaling pathways, including MHC-I and MHC-II, were attenuated in MDA5+ DM with RPILD. Notably, MHC-II signaling was absent in CD4+ naïve T cells from MDA5+ DM with RPILD. This study demonstrates that antiviral response plays an important role in the pathogenesis of MDA5+ DM with RPILD, as well as changes in downstream immune pathways, providing potential therapeutic targets for future treatment.

Type I interferons (IFN-Is) constitute the primary defense mechanism against pathogenic infections in the human body. The antiviral signaling mediated by IFN-I is integral to the host immune response. Nevertheless, an imbalance in IFN-I function can perturb the organism’s homeostasis. Consequently, it is imperative for the body to meticulously regulate the intensity and duration of the IFN-I signaling cascade. These regulations ensure the effective execution of antiviral and antitumor functions advantageous to the host while preventing deleterious cytotoxic effects that may arise from aberrant signal activation. Post-translational modifications (PTMs) play a crucial role in establishing a precise and dynamic regulatory network for IFN-I signaling. Classical PTMs, including phosphorylation, ubiquitination, and acetylation, target various signaling molecules to effectively modulate the transduction of the IFN-I signaling pathway. This review synthesizes recent advancements in understanding the regulation of IFN-I signaling pathways by PTMs, with the aim of offering novel insights for the clinical application of IFN-I.

BackgroundAnti-programmed cell death protein 1 (anti-PD-1) antibodies have achieved revolutionary success in cancer therapy. However, the impact of anti-PD-1 therapy on host humoral immunity in humans during cancer immunotherapy requires further investigation.MethodsWe evaluated immunoglobulin titers by ELISA and screened the immune landscape of immune cells from 25 healthy donors and 50 cases including 25 new-onset hepatocellular carcinoma (HCC) patients prior to systemic treatment and 25 HCC patients undergoing anti-PD-1 therapy by multicolor flow cytometry. Flow or beads sorted cells were cultured ex vivo for proliferation and functional analysis.ResultsAnti-PD-1 therapy significantly increased the levels of IgG and IgA in the periphery of HCC patients. Anti-PD-1 treatment led to an increase in plasmablasts and a notable rise in circulating T follicular regulatory (cTfr) cells, while changes in circulating B cells, T follicular helper cells, or regulatory T cells were not significant. Anti-PD-1 therapy also influenced the proliferation and function of cTfr cells, promoting the differentiation of CD38+cTfr cells. We observed that the CD38+Tfr cell subset in the peripheral blood can promote plasmablast differentiation, associated with altered antibody production.ConclusionsTogether, these data demonstrate the immunomodulatory role of PD-1 in restricting the differentiation and function of human cTfr cells and in regulating humoral immunity.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) generally hijacks the cellular machinery of host cells for survival. However, how SARS-CoV-2 employs the host's deubiquitinase to facilitate virus replication remains largely unknown. In this study, we identified the host deubiquitinase USP22 as a crucial regulator of the expression of SARS-CoV-2 nucleocapsid protein (SARS-CoV-2 NP), which is essential for SARS-CoV-2 replication. We demonstrated that SARS-CoV-2 NP proteins undergo ubiquitination-dependent degradation in host cells, while USP22 interacts with SARS-CoV-2 NP and downregulates K63-linked polyubiquitination of SARS-CoV-2 NP, thereby protecting SARS-CoV-2 NP from degradation. Importantly, we further revealed that sulbactam, an antibiotic, can reduce USP22 protein levels, eventually promoting the degradation of SARS-CoV-2 NP in vitro and in vivo. This study reveals the mechanism by which SARS-CoV-2-encoded NP protein employs host deubiquitinase for virus survival and provides a potential strategy to fight against SARS-CoV-2 infection.IMPORTANCESevere acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nucleocapsid protein (SARS-CoV-2 NP) plays a pivotal role in viral infection by binding to viral RNA, stabilizing the viral genome, and promoting replication. However, the interactions between SARS-CoV-2 NP and host intracellular proteins had not been elucidated. In this study, we provide evidence that SARS-CoV-2 NP interacts with the deubiquitinase USP22 in host cells, which downregulates SARS-CoV-2 NP ubiquitination. This reduction in ubiquitination effectively prevents intracellular degradation of SARS-CoV-2 NP, thereby enhancing its stability, marking USP22 as a potential target for antiviral strategies. Additionally, our findings indicate that sulbactam significantly decreases the protein levels of USP22, thereby reducing SARS-CoV-2 NP levels. This discovery suggests a novel therapeutic pathway in which sulbactam could be repurposed as an antiviral agent, demonstrating how certain antibiotics might contribute to antiviral treatment. This work thus opens avenues for drug repurposing and highlights the therapeutic potential of targeting host pathways to inhibit viral replication.

Nipah virus (NiV) is a severe zoonotic pathogen that substantially threatens public health. Pigs are the natural hosts of NiV and can potentially transmit this disease to humans. Establishing a rapid, sensitive, and accurate point-of-care detection method is critical in the timely identification of infected pig herds. In this study, we developed an NiV detection method based on reverse transcription–recombinase polymerase amplification (RT-RAA) and the clustered regularly interspaced short palindromic repeats (CRISPR)-associated protein 13a (Cas13a) system for the precise detection of NiV. The highly conserved region of the NiV gene was selected as the detection target. We first designed eleven pairs of RT-RAA primers, and the optimal primer combination and reaction temperature were identified on the basis of RT-RAA efficiency. Additionally, the most efficient crRNA sequence was selected on the basis of the fluorescence signal intensity. The results revealed that the optimal reaction temperature for the developed method was 37 °C. The detection limit was as low as 1.565 copies/μL. Specificity testing revealed no cross-reactivity with nucleic acids from six common swine viruses, including Seneca virus A (SVA), foot-and-mouth disease virus (FMDV), classical swine fever virus (CSFV), porcine epidemic diarrhea virus (PEDV), African swine fever virus (ASFV), and pseudorabies virus (PRV). A validation test using simulated clinical samples revealed a 100% concordance rate. The detection results can be visualized via a fluorescence reader or lateral flow strips (LFSs). Compared with conventional detection methods, this RT-RAA-CRISPR/Cas13a-based method is rapid and simple and does not require scientific instruments. Moreover, the reagents can be freeze-dried for storage, eliminating the need for cold-chain transportation. This detection technology provides a convenient and efficient new tool for the point-of-care diagnosis of NiV and for preventing and controlling outbreaks.

Innate immunity is an important component of the immune system and serves as the first line of defense for the host against the invasion of foreign pathogens. Viperin (RSAD2), a core member of the interferon-stimulated gene (ISG) family, plays a key role in innate immunity through direct inhibition of viral replication and modulation of the host immune–metabolic network. The intracellular expression of Viperin rises markedly after viral infection or interferon-induced induction, showing a wide range of antiviral activities. In recent years, the versatility of Viperin in viral infections, autoimmune diseases, and tumor immune metabolism has been gradually revealed. Here, we summarize and discuss the gene regulatory network, molecular functions, and multi-dimensional roles of Viperin in diseases to provide a theoretical basis for the development of broad-spectrum antiviral strategies and immunometabolic therapies based on Viperin.

Metabolic diseases, including obesity, diabetes, and metabolic‐associated fatty liver disease (MAFLD), are increasingly common worldwide, posing a significant public health challenge. Recent research has revealed a complex interplay between these metabolic disorders and interferon (IFN) immune responses. As key immune regulators, interferons coordinate the host's defense against viral infections and are essential for maintaining immune homeostasis. However, metabolic dysregulation can significantly disrupt IFN signaling pathways, affecting the intensity and efficiency of immune responses. Conversely, alterations in IFN signaling can influence the onset and progression of metabolic diseases. This review explores the mechanisms by which metabolic diseases modulate IFN responses, focusing on how obesity, diabetes, and MAFLD alter IFN signaling. Additionally, we examine the implications of the changes in IFN immune responses for the progression of metabolic diseases. By synthesizing current research, this review aims to elucidate the interplay between IFN immune responses and common metabolic diseases, offering insights for future research and clinical applications in the field of IFN‐related metabolic diseases.

Coxsackievirus B3 (CVB3)-induced acute heart failure (AHF) is a common cause of cardiogenic death in young- and middle-aged people. However, the key molecular events linking CVB3 to AHF remain largely unknown, resulting in a lack of targeted therapy strategies thus far. Here, we unexpectedly found that Viperin deficiency does not promote CVB3 infection but protects mice from CVB3-induced AHF. Importantly, cardiac-specific expression of Viperin can induce cardiac dysfunction. Mechanistically, CVB3-encoded 3C protease rescues Viperin protein expression in cardiomyocytes by lowering UBE4A. Viperin in turn interacts with and reduces STAT1 to activate SGK1-KCNQ1 signaling, and eventually leads to cardiac electrical dysfunction and subsequent AHF. Furthermore, we designed an interfering peptide VS-IP1, which blocked Viperin-mediated STAT1 degradation and therefore prevented CVB3-induced AHF. This study established the first signaling link between CVB3 and cardiac electrical dysfunction, and revealed the potential of interfering peptides targeting Viperin for the treatment of CVB3-induced AHF.

The classic dual luciferase reporter assay has been widely used to rapidly and accurately determine the transcriptional activity of a given promoter induced by certain signal pathways in the cells. In particular, the sensitive characteristics of luciferase highlight its significance in many experiments, such as weak promoter analysis, transfection studies using small amounts of DNA, and detection in cell lines with low transfection efficiency. This chapter presents detailed information and experimental procedures for measuring interferon (IFN)-induced Interferon-Stimulated Response Element (ISRE) promoter activity using the dual luciferase reporter assay.