Single-cell sequencing combined with spatial transcriptomics reveals that the IRF7 gene in M1 macrophages inhibits the occurrence of pancreatic cancer by regulating lipid metabolism-related mechanisms.

AIM: The main focus of this study is to explore the molecular mechanism of IRF7 regulation on RPS18 transcription in M1-type macrophages in pancreatic adenocarcinoma (PAAD) tissue, as well as the transfer of RPS18 by IRF7 via exosomes to PAAD cells and the regulation of ILF3 expression. METHODS: By utilising single-cell RNA sequencing (scRNA-seq) data and spatial transcriptomics (ST) data from the Gene Expression Omnibus database, we identified distinct cell types with significant expression differences in PAAD tissue. Among these cell types, we identified those closely associated with lipid metabolism. The differentially expressed genes within these cell types were analysed, and target genes relevant to prognosis were identified. Flow cytometry was employed to assess the expression levels of target genes in M1 and M2 macrophages. Cell lines with target gene knockout were constructed using CRISPR/Cas9 editing technology, and cell lines with target gene knockdown and overexpression were established using lentiviral vectors. Additionally, a co-culture model of exosomes derived from M1 macrophages with PAAD cells was developed. The impact of M1 macrophage-derived exosomes on the lipid metabolism of PAAD cells in the model was evaluated through metabolomics analysis. The effects of M1 macrophage-derived exosomes on the viability, proliferation, division, migration and apoptosis of PAAD cells were assessed using MTT assay, flow cytometry, EdU assay, wound healing assay, Transwell assay and TUNEL staining. Furthermore, a mouse PAAD orthotopic implantation model was established, and bioluminescence imaging was utilised to assess the influence of M1 macrophage-derived exosomes on the intratumoural formation capacity of PAAD cells, as well as measuring tumour weight and volume. The expression of proliferation-associated proteins in tumour tissues was examined using immunohistochemistry. RESULTS: Through combined analysis of scRNA-seq and ST technologies, we discovered a close association between M1 macrophages in PAAD samples and lipid metabolism signals, as well as a negative correlation between M1 macrophages and cancer cells. The construction of a prognostic risk score model identified RPS18 and IRF7 as two prognostically relevant genes in M1 macrophages, exhibiting negative and positive correlations, respectively. Mechanistically, it was found that IRF7 in M1 macrophages can inhibit the transcription of RPS18, reducing the transfer of RPS18 to PAAD cells via exosomes, consequently affecting the expression of ILF3 in PAAD cells. IRF7/RPS18 in M1 macrophages can also suppress lipid metabolism, cell viability, proliferation, migration, invasion and intratumoural formation capacity of PAAD cells, while promoting cell apoptosis. CONCLUSION: Overexpression of IRF7 in M1 macrophages may inhibit RPS18 transcription, reduce the transfer of RPS18 from M1 macrophage-derived exosomes to PAAD cells, thereby suppressing ILF3 expression in PAAD cells, inhibiting the lipid metabolism pathway, and curtailing the viability, proliferation, migration, invasion of PAAD cells, as well as enhancing cell apoptosis, ultimately inhibiting tumour formation in PAAD cells in vivo. Targeting IRF7/RPS18 in M1 macrophages could represent a promising immunotherapeutic approach for PAAD in the future.

Kaempferol Alleviates Injury in Human Retinal Pigment Epithelial Cells via STAT1 Ubiquitination-Mediated Degradation of IRF7.

BACKGROUND: Retinal pigment epithelial (RPE) cells have a pivotal function in preserving the equilibrium of the retina and moderating the immunological interaction between the choroid and the retina. This study primarily focuses on delineating the protective effect offered by Kaempferol (Kae) against RPE cell damage. METHODS: Bioinformatics analysis was performed on the GSE30719 dataset to identify hub genes associated with RPE. Subsequently, we analyzed the impact of Kae on RPE apoptosis, cell viability, and inflammatory response through cell experiments, and explored the interaction between hub genes and Kae. RESULTS: Based on the GSE30719 dataset, nine hub genes (ISG15, IFIT1, IFIT3, STAT1, OASL, RSAD2, IRF7, MX2, and MX1) were identified, all of which were highly expressed in the GSE30719 case group. Kae could boost the proliferative activity of RPE cells caused by lipopolysaccharide (LPS), as well as reduce apoptosis and the generation of inflammatory factors (tumor necrosis factor receptor (TNFR), interleukin-1beta (IL-1ß)) and cytokines (IL-1, IL-6, IL-12). STAT1 was shown to inhibit cell proliferation, promote apoptosis, and secrete IL-1/IL-6/IL-12 in LPS-induced RPE cells. Moreover, IRF7 was found to interact with STAT1 in LPS-induced RPE cells, and STAT1 could maintain IRF7 levels through deubiquitination. In addition, we also found that the protective effect of Kae on LPS-induced RPE cell injury was mediated through STAT1/IRF7 axis. CONCLUSION: This study provided evidence that Kae protects RPE cells via regulating the STAT1/IRF7 signaling pathways, indicating its potential therapeutic relevance in the diagnosis and management of retinal disorders linked with RPE cell damage.

IRF7 overexpression alleviates CFA-induced inflammatory pain by inhibiting nuclear factor-κB activation and pro-inflammatory cytokines expression in rats.

BACKGROUND: It is known that nerve signals arising from sites of inflammation lead to persistent changes in the spinal cord and contribute to the amplification and persistence of pain. Nevertheless, the underlying mechanisms have not yet been completely elucidated. We identified differentially expressed genes in the lumbar (L4-L6) segment of the spinal cord from complete Freund's adjuvant (CFA) rats compared to control animals via high throughput sequencing. Based on differential gene expression analysis, we selected interferon regulatory factor 7 (IRF7) for follow-up experiments to explore its antinociceptive potential. METHODS: An animal model of inflammatory pain was induced by intraplantar injection of CFA. We evaluated the effects of adeno-associated viral (AAV)-mediated overexpression of IRF7 in the spinal cord on pain-related behavior after CFA injection. Moreover, the activation of the nuclear factor-κB (NF-κB) and the expression of inflammatory cytokines were investigated to understand the underlying mechanisms related to the contribution of IRF7 to inflammatory pain. RESULTS: CFA intraplantar injection caused a significant decrease in the level of spinal IRF7, which is mainly expressed in the dorsal horn neurons and astrocytes. Moreover, IRF7 overexpression significantly attenuated pain-related behaviors, as well as the activity of NF-κB/p65 and the production of interleukin-1ß (IL-1ß), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) in the spinal cord of CFA rats. CONCLUSIONS: Our data indicated that spinal IRF7 plays an important role in the regulation of inflammatory pain. Thus, IRF7 overexpression at the spinal cord level might represent a potential target for the treatment of inflammatory pain.

IRF7 Exacerbates Candida albicans Infection by Compromising CD209-Mediated Phagocytosis and Autophagy-Mediated Killing in Macrophages.

IFN regulatory factor 7 (IRF7) exerts anti-infective effects by promoting the production of IFNs in various bacterial and viral infections, but its role in highly morbid and fatal Candida albicans infections is unknown. We unexpectedly found that Irf7 gene expression levels were significantly upregulated in tissues or cells after C. albicans infection in humans and mice and that IRF7 actually exacerbates C. albicans infection in mice independent of its classical function in inducing IFNs production. Compared to controls, Irf7-/- mice showed stronger phagocytosis of fungus, upregulation of C-type lectin receptor CD209 expression, and enhanced P53-AMPK-mTOR-mediated autophagic signaling in macrophages after C. albicans infection. The administration of the CD209-neutralizing Ab significantly hindered the phagocytosis of Irf7-/- mouse macrophages, whereas the inhibition of p53 or autophagy impaired the killing function of these macrophages. Thus, IRF7 exacerbates C. albicans infection by compromising the phagocytosis and killing capacity of macrophages via regulating CD209 expression and p53-AMPK-mTOR-mediated autophagy, respectively. This finding reveals a novel function of IRF7 independent of its canonical IFNs production and its unexpected role in enhancing fungal infections, thus providing more specific and effective targets for antifungal therapy.

Loss of RBM45 inhibits breast cancer progression by reducing the SUMOylation of IRF7 to promote IFNB1 transcription.

Type I interferons exhibit anti-proliferative and anti-cancer activities, but their detailed regulatory mechanisms in cancer have not been fully elucidated yet. RNA binding proteins are master orchestrators of gene regulation, which are closely related to tumor progression. Here we show that the upregulated RNA binding protein RBM45 correlates with poor prognosis in breast cancer. Depletion of RBM45 suppresses breast cancer progression both in cultured cells and xenograft mouse models. Mechanistically, RBM45 ablation inhibits breast cancer progression through regulating type I interferon signaling, particularly by elevating IFN-ß production. Importantly, RBM45 recruits TRIM28 to IRF7 and stimulates its SUMOylation, thereby repressing IFNB1 transcription. Loss of RBM45 reduced the SUMOylation of IRF7 by reducing the interaction between TRIM28 and IRF7 to promote IFNB1 transcription, leading to the inhibition of breast cancer progression. Taken together, our finding uncovers a vital role of RBM45 in modulating type I interferon signaling and cancer aggressive progression, implicating RBM45 as a potential therapeutic target in breast cancer.

Mitochondrial (mt)DNA-cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) signaling promotes pyroptosis of macrophages via interferon regulatory factor (IRF)7/IRF3 activation to aggravate lung injury during severe acute pancreatitis.

BACKGROUND: Macrophage proinflammatory activation contributes to the pathology of severe acute pancreatitis (SAP) and, simultaneously, macrophage functional changes, and increased pyroptosis/necrosis can further exacerbate the cellular immune suppression during the process of SAP, where cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) plays an important role. However, the function and mechanism of cGAS-STING in SAP-induced lung injury (LI) remains unknown. METHODS: Lipopolysaccharide (LPS) was combined with caerulein-induced SAP in wild type, cGAS -/- and sting -/- mice. Primary macrophages were extracted via bronchoalveolar lavage and peritoneal lavage. Ana-1 cells were pretreated with LPS and stimulated with nigericin sodium salt to induce pyroptosis in vitro. RESULTS: SAP triggered NOD-, LRR-, and pyrin domain-containing protein 3 (NLRP3) inflammasome activation-mediated pyroptosis of alveolar and peritoneal macrophages in mouse model. Knockout of cGAS/STING could ameliorate NLRP3 activation and macrophage pyroptosis. In addition, mitochondrial (mt)DNA released from damaged mitochondria further induced macrophage STING activation in a cGAS- and dose-dependent manner. Upregulated STING signal can promote NLRP3 inflammasome-mediated macrophage pyroptosis and increase serum interleukin (IL)-6, IL-1ß, and tumor necrosis factor (TNF)-α levels and, thus, exacerbate SAP-associated LI (SAP-ALI). Downstream molecules of STING, IRF7, and IRF3 connect the mtDNA-cGAS-STING axis and the NLRP3-pyroptosis axis. CONCLUSIONS: Negative regulation of any molecule in the mtDNA-cGAS-STING-IRF7/IRF3 pathway can affect the activation of NLRP3 inflammasomes, thereby reducing macrophage pyroptosis and improving SAP-ALI in mouse model.

The dsRNA isolated from Escherichia coli infected with the MS2 bacteriophage induces the production of interferons.

Viral infections pose a significant threat to public health, and the production of interferons represents one of the most critical antiviral innate immune responses of the host. Consequently, the screening and identification of compounds or reagents that induce interferon production are of paramount importance. This study commenced with the cultivation of host bacterium 15,597, followed by the infection of Escherichia coli with the MS2 bacteriophage. Utilizing the J2 capture technique, a class of dsRNA mixtures (MS2+15,597) was isolated from the E. coli infected with the MS2 bacteriophage. Subsequent investigations were conducted on the immunostimulatory activity of the MS2+15,597 mixture. The results indicated that the dsRNA mixtures (MS2+15,597) extracted from E. coli infected with the MS2 bacteriophage possess the capability to activate innate immunity, thereby inducing the production of interferon-ß. These dsRNA mixtures can activate the RIG-I and TLR3 pattern recognition receptors, stimulating the expression of interferon stimulatory factors 3/7, which in turn triggers the NF-κB signaling pathway, culminating in the cellular production of interferon-ß to achieve antiviral effects. This study offers novel insights and strategies for the development of broad-spectrum antiviral drugs, potentially providing new modalities for future antiviral therapies.

Non-transcriptional IRF7 interacts with NF-κB to inhibit viral inflammation.

Interferon (IFN) regulatory factors (IRF) are key transcription factors in cellular antiviral responses. IRF7, a virus-inducible IRF, expressed primarily in myeloid cells, is required for transcriptional induction of interferon α and antiviral genes. IRF7 is activated by virus-induced phosphorylation in the cytoplasm, leading to its translocation to the nucleus for transcriptional activity. Here, we revealed a nontranscriptional activity of IRF7 contributing to its antiviral functions. IRF7 interacted with the pro-inflammatory transcription factor NF-κB-p65 and inhibited the induction of inflammatory target genes. Using knockdown, knockout, and overexpression strategies, we demonstrated that IRF7 inhibited NF-κB-dependent inflammatory target genes, induced by virus infection or toll-like receptor stimulation. A mutant IRF7, defective in transcriptional activity, interacted with NF-κB-p65 and suppressed NF-κB-induced gene expression. A single-action IRF7 mutant, active in anti-inflammatory function, but defective in transcriptional activity, efficiently suppressed Sendai virus and murine hepatitis virus replication. We, therefore, uncovered an anti-inflammatory function for IRF7, independent of transcriptional activity, contributing to the antiviral response of IRF7.

Type I Interferon, Induced by Adenovirus or Adenoviral Vector Infection, Regulates the Cytokine Response to Lipopolysaccharide in a Macrophage Type-Specific Manner.

INTRODUCTION: While TLR ligands derived from microbial flora and pathogens are important activators of the innate immune system, a variety of factors such as intracellular bacteria, viruses, and parasites can induce a state of hyperreactivity, causing a dysregulated and potentially life-threatening cytokine over-response upon TLR ligand exposure. Type I interferon (IFN-αß) is a central mediator in the induction of hypersensitivity and is strongly expressed in splenic conventional dendritic cells (cDC) and marginal zone macrophages (MZM) when mice are infected with adenovirus. This study investigates the ability of adenoviral infection to influence the activation state of the immune system and underlines the importance of considering this state when planning the treatment of patients. METHODS: Infection with adenovirus-based vectors (Ad) or pretreatment with recombinant IFN-ß was used as a model to study hypersensitivity to lipopolysaccharide (LPS) in mice, murine macrophages, and human blood samples. The TNF-α, IL-6, IFN-αß, and IL-10 responses induced by LPS after pretreatment were measured. Mouse knockout models for MARCO, IFN-αßR, CD14, IRF3, and IRF7 were used to probe the mechanisms of the hypersensitive reaction. RESULTS: We show that, similar to TNF-α and IL-6 but not IL-10, the induction of IFN-αß by LPS increases strongly after Ad infection. This is true both in mice and in human blood samples ex vivo, suggesting that the regulatory mechanisms seen in the mouse are also present in humans. In mice, the scavenger receptor MARCO on IFN-αß-producing cDC and splenic marginal zone macrophages is important for Ad uptake and subsequent cytokine overproduction by LPS. Interestingly, not all IFN-αß-pretreated macrophage types exposed to LPS exhibit an enhanced TNF-α and IL-6 response. Pretreated alveolar macrophages and alveolar macrophage-like murine cell lines (MPI cells) show enhanced responses, while bone marrow-derived and peritoneal macrophages show a weaker response. This correlates with the respective absence or presence of the anti-inflammatory IL-10 response in these different macrophage types. In contrast, Ad or IFN-ß pretreatment enhances the subsequent induction of IFN-αß in all macrophage types. IRF3 is dispensable for the LPS-induced IFN-αß overproduction in infected MPI cells and partly dispensable in infected mice, while IRF7 is required. The expression of the LPS co-receptor CD14 is important but not absolutely required for the elicitation of a TNF-α over-response to LPS in Ad-infected mice. CONCLUSION: Viral infections or application of virus-based vaccines induces type I interferon and can tip the balance of the innate immune system in the direction of hyperreactivity to a subsequent exposure to TLR ligands. The adenoviral model presented here is one example of how multiple factors, both environmental and genetic, affect the physiological responses to pathogens. Being able to measure the current reactivity state of the immune system would have important benefits for infection-specific therapies and for the prevention of vaccination-elicited adverse effects.

A BET inhibitor, NHWD-870, can downregulate dendritic cells maturation via the IRF7-mediated signaling pathway to ameliorate imiquimod-induced psoriasis-like murine skin inflammation.

Psoriasis is a chronic, recurrent, inflammatory dermatosis accompanied by excessive activation of dendritic cells (DCs), which are primarily responsible for initiating an immune response. The bromodomain and extraterminal domain (BET) family plays a pivotal role in the transcriptional regulation of inflammation and its inhibitors can downregulate DCs maturation and activation. Here we investigated the effect of NHWD-870, a potent BET inhibitor, on inflammation in an imiquimod (IMQ)-induced psoriasis-like mouse model and murine bone marrow-derived dendritic cells (BMDCs) stimulated by lipopolysaccharide (LPS) and IMQ. Application of NHWD-870 significantly ameliorated IMQ-triggered skin inflammation in mice, and markers associated with DC maturation (CD40, CD80 and CD86) were decreased in skin lesions, spleen and lymph nodes. Additionally, NHWD-870 reduced LPS or IMQ induced DCs maturation and activation in vitro, with lower expression of inflammatory cytokines [interleukin (IL)-12, IL-23, tumor necrosis factor-α, IL-6, IL-1ß, chemokine (C-X-C motif) ligand (CXCL)9 and CXCL10]. In addition, we found that interferon regulatory factor 7 (IRF7) significantly increased during DCs maturation, and inhibition of IRF7 could impair BMDCs maturation and activation. What's more, IRF7 was highly expressed in both psoriatic patients and IMQ-induced psoriasis-like mice. Single-cell RNA sequencing of normal and psoriatic skin demonstrated that IRF7 expression was increased in DCs of psoriatic skin. While NHWD-870 could inhibit IRF7 and phosphorylated-IRF7 expression in vivo and in vitro. These results indicate that NHWD-870 suppresses the maturation and activation of DCs by decreasing IRF7 proteins which finally alleviates psoriasis-like skin lesions, and NHWD-870 may be a potent therapeutic drug for psoriasis.

The neuroprotective effect of near infrared light therapy in aged mice with postoperative neurocognitive disorder by upregulating IRF7.

BACKGROUND: Postoperative neurocognitive disorder (PND) is a common central nervous system complication after undergoing surgery and anesthesia especially in elderly patients, while the therapeutic options are very limited. This study was carried out to investigate the beneficial effects of transcranial near infrared light (NIRL) which was employed to the treatment of PND and propose the involved mechanisms. METHODS: The PND mice were established through left carotid artery exposure under isoflurane anesthesia and received transcranial NIRL treatment. Behavioral testing was performed to evaluate the cognitive function of PND mice after transcranial NIRL therapy. Changes in the transcriptomic profiles of prefrontal cortex (PFC) and hippocampus (HP) were identified by next generation sequencing (NGS), and the molecular mechanisms involved were examined by both in vivo mouse model and in vitro cell culture studies. RESULTS: We found that transcranial NIRL therapy effectively ameliorated learning and memory deficit induced by anesthesia and surgery in aged mice. Specifically, we identified down-regulation of interferon regulatory factor 7 (IRF7) in the brains of PND mice that was mechanistically associated with increased pro-inflammatory M1 phenotype of microglia and elevated neuroinflammatory. NIRL treatment produced protective effects through the upregulation of IRF7 expression and reversing microglial phenotypes from pro-inflammatory to neuroprotective, resulting in reduced brain damage and improved cognitive function in PND mice. CONCLUSION: Our results indicate that transcranial NIRL is an effective and safe therapy for PND via alleviating neuroinflammation, and IRF7 plays a key transcription factor in regulating the M1-to-M2 switch of microglia.

Melanoma Derived Exosomes Amplify Radiotherapy Induced Abscopal Effect via IRF7/I-IFN Axis in Macrophages.

Radiotherapy (RT) can induce tumor regression outside the irradiation field, known as the abscopal effect. However, the detailed underlying mechanisms remain largely unknown. A tumor-bearing mouse model is successfully constructed by inducing both subcutaneous tumors and lung metastases. Single-cell RNA sequencing, immunofluorescence, and flow cytometry are performed to explore the regulation of tumor microenvironment (TME) by RT. A series of in vitro assays, including luciferase reporter, RNA Pulldown, and fluorescent in situ hybridization (FISH) assays, are performed to evaluate the detailed mechanism of the abscopal effect. In addition, in vivo assays are performed to investigate combination therapy strategies for enhancing the abscopal effect. The results showed that RT significantly inhibited localized tumor and lung metastasis progression and improved the TME. Mechanistically, RT promoted the release of tumor-derived exosomes carrying circPIK3R3, which is taken up by macrophages. circPIK3R3 promoted Type I interferon (I-IFN) secretion and M1 polarization via the miR-872-3p/IRF7 axis. Secreted I-IFN activated the JAK/STAT signaling pathway in CD8+ T cells, and promoted IFN-γ and GZMB secretion. Together, the study shows that tumor-derived exosomes promote I-IFN secretion via the circPIK3R3/miR-872-3p/IRF7 axis in macrophages and enhance the anti-tumor immune response of CD8+ T cells.

Role of macrophage colony stimulating factor and interferon regulatory factor 7 in modulating the immune profile of mouse testicular macrophages.

Testicular macrophages (TM) are critical for the function of the testis by regulating homeostasis and inflammatory responses. However, the mechanisms by which TM fulfil these roles remain elusive. In this study, we explored the impact of two key testicular microenvironmental factors, namely 25-hydroxycholesterol (25HC), an oxysterol related to sex hormones and macrophage colony-stimulating factor (M-CSF), a factor crucial for macrophage survival and differentiation, on the regulation of the TM phenotype. Specifically, we examined their role in controlling the expression of the transcription factor interferon regulatory factor 7 (Irf7), a factor critical for maintaining the alternative macrophage phenotype. To achieve this, we used an in vitro bone marrow-derived macrophage (BMDM) model as a surrogate for TM to investigate the roles of 25HC and M-CSF in regulating the expression of Irf7 during the polarization of murine TM. M-CSF was identified as the main regulator of Irf7 expression, while 25HC production is a consequence of Irf7 activation in BMDM. In turn, 25HC plays a role in a negative feedback loop on the expression levels of Irf7 in BMDM. Using flow cytometry in Irf7-/- mouse testis the CD64loMHChi TM subpopulation was found to be decreased. Together with lower IL-10 protein levels in Irf7-/- TM this indicates a shift towards an M1-like macrophage profile. In summary, our data indicates that M-CSF could act as an inducer of high Irf7 expression levels in the mouse testis. However, the exact role of the high 25HC concentration in the testis in maintaining the local immune milieu still needs further study.

Decitabine induces IRF7-mediated immune responses in p53-mutated triple-negative breast cancer: a clinical and translational study.

p53 is mutated in half of cancer cases. However, no p53-targeting drugs have been approved. Here, we reposition decitabine for triple-negative breast cancer (TNBC), a subtype with frequent p53 mutations and extremely poor prognosis. In a retrospective study on tissue microarrays with 132 TNBC cases, DNMT1 overexpression was associated with p53 mutations (P = 0.037) and poor overall survival (OS) (P = 0.010). In a prospective DEciTabinE and Carboplatin in TNBC (DETECT) trial (NCT03295552), decitabine with carboplatin produced an objective response rate (ORR) of 42% in 12 patients with stage IV TNBC. Among the 9 trialed patients with available TP53 sequencing results, the 6 patients with p53 mutations had higher ORR (3/6 vs. 0/3) and better OS (16.0 vs. 4.0 months) than the patients with wild-type p53. In a mechanistic study, isogenic TNBC cell lines harboring DETECT-derived p53 mutations exhibited higher DNMT1 expression and decitabine sensitivity than the cell line with wild-type p53. In the DETECT trial, decitabine induced strong immune responses featuring the striking upregulation of the innate immune player IRF7 in the p53-mutated TNBC cell line (upregulation by 16-fold) and the most responsive patient with TNBC. Our integrative studies reveal the potential of repurposing decitabine for the treatment of p53-mutated TNBC and suggest IRF7 as a potential biomarker for decitabine-based treatments.

Augmented interferon regulatory factor 7 axis in whole tumor cell vaccines prevents tumor recurrence by inducing interferon gamma-secreting B cells.

Among cancer immunotherapy, which has received great attention in recent years, cancer vaccines can potentially prevent recurrent tumors by using the exquisite power and specificity of the immune system. Specifically, whole tumor cell vaccines (WTCVs) based on surgically resected tumors have been considered to elicit robust anti-tumor immune responses by exposing various tumor-associated antigens to host immunity. However, most tumors have little immunogenicity because of immunoediting by continuous interactions with host immunity; thus, preparing WTCVs based on patient-derived non-modified tumors cannot prevent tumor onset. Hence, the immunogenicity of tumor cells must be improved for effective WTCVs. In this study, we indicate the importance of the interferon regulatory factor 7 (Irf7) axis, including Irf7 and its downstream factors, within tumor cells in regulating immunogenicity. Indeed, WTCVs that augmented the Irf7 axis have exerted remarkable recurrence-preventive effects when vaccinated after tumor inactivation by radiation. Most notably, vaccination with murine colon cancer cells that enhanced the Irf7 axis prevented the development of challenged tumors in all mice and resulted in a 100% survival rate during the observation period. Furthermore, the mechanism leading to vaccine effectiveness was mediated by interferon-gamma-producing B cells. This study provides novel insights into how to enhance tumor immunogenicity and use WTCVs as recurrence prophylaxis.

Interferon regulatory factor 7 in inflammation, cancer and infection.

Interferon regulatory factor 7 (IRF7), a member of the interferon regulatory factors (IRFs) family, is located downstream of the pattern recognition receptors (PRRs)-mediated signaling pathway and is essential for the production of type I interferon (IFN-I). Activation of IRF7 inhibits various viral and bacterial infections and suppresses the growth and metastasis of some cancers, but it may also affect the tumor microenvironment and promote the development of other cancers. Here, we summarize recent advances in the role of IRF7 as a multifunctional transcription factor in inflammation, cancer and infection by regulating IFN-I production or IFN-I-independent signaling pathways.

Delayed CO2 postconditioning promotes neurological recovery after cryogenic traumatic brain injury by downregulating IRF7 expression.

AIMS: Few treatments are available in the subacute phase of traumatic brain injury (TBI) except rehabilitation training. We previously reported that transient CO2 inhalation applied within minutes after reperfusion has neuroprotective effects against cerebral ischemia/reperfusion injury. In this study, it was hypothesized that delayed CO2 postconditioning (DCPC) starting at the subacute phase may promote neurological recovery of TBI. METHODS: Using a cryogenic TBI (cTBI) model, mice received DCPC daily by inhaling 5%/10%/20% CO2 for various time-courses (one/two/three cycles of 10-min inhalation/10-min break) at Days 3-7, 3-14 or 7-18 after cTBI. Beam walking and gait tests were used to assess the effect of DCPC. Lesion size, expression of GAP-43 and synaptophysin, amoeboid microglia number and glia scar area were detected. Transcriptome and recombinant interferon regulatory factor 7 (Irf7) adeno-associated virus were applied to investigate the molecular mechanisms. RESULTS: DCPC significantly promoted recovery of motor function in a concentration and time-course dependent manner with a wide therapeutic time window of at least 7 days after cTBI. The beneficial effects of DCPC were blocked by intracerebroventricular injection of NaHCO3 . DCPC also increased puncta density of GAP-43 and synaptophysin, and reduced amoeboid microglia number and glial scar formation in the cortex surrounding the lesion. Transcriptome analysis showed many inflammation-related genes and pathways were altered by DCPC, and Irf7 was a hub gene, while overexpression of IRF7 blocked the motor function improvement of DCPC. CONCLUSIONS: We first showed that DCPC promoted functional recovery and brain tissue repair, which opens a new therapeutic time window of postconditioning for TBI. Inhibition of IRF7 is a key molecular mechanism for the beneficial effects of DCPC, and IRF7 may be a potential therapeutic target for rehabilitation after TBI.

NF-κB p65 and SETDB1 expedite lipopolysaccharide-induced intestinal inflammation in mice by inducing IRF7/NLR-dependent macrophage M1 polarization.

Macrophages exhibit distinct phenotypes that are pro-inflammatory (M1) or anti-inflammatory (M2) in response to inflammation. In this study, we tried to identify the roles and mechanisms of interferon regulatory factor 7 (IRF7) in modulating the phenotypes of macrophages in lipopolysaccharide (LPS)-induced intestinal inflammation. The mouse model of intestinal inflammation was induced by lipopolysaccharide (LPS), and mouse bone marrow-derived macrophages (BMDMs) and mouse intestinal epithelial cells were selected for experimental verification in vitro. Results demonstrated that IRF7 was highly expressed in the mouse model of intestinal inflammation, while IRF7 deficiency repressed macrophage M1 polarization and attenuated intestinal inflammation in mice. p65 and SET domain bifurcated 1 (SETDB1) synergistically promoted histone 3 lysine 4 trimethylation (H3K4me3) methylation to elevate IRF7 expression, which activated the Nod-like receptor (NLR) pathway to induce macrophage M1 polarization. Through this mechanism, IRF7 in BMDMs functioned to accelerate intestinal epithelial cell apoptosis and their release of pro-inflammatory proteins. Furthermore, the promoting effect of p65 and SETDB1 on LPS-induced intestinal inflammation was validated in vivo. To sum up, NF-κB p65 and SETDB1 facilitated IRF7-mediated macrophage M1 polarization, thereby aggravating the LPS-induced intestinal inflammation. Hence, this study highlights the appealing value of these factors as anti-inflammatory targets.

Avian Reovirus σA Protein Inhibits Type I Interferon Production by Abrogating Interferon Regulatory Factor 7 Activation.

Type I interferon (IFN) response is the first line of host-based innate immune defense against viral infections. However, viruses have developed multiple strategies to counter host IFN responses, so they may continue infecting hosts via effective replication. Avian reovirus (ARV), an RNA virus, causes viral arthritis or tenosynovitis in chickens. Previous studies have shown that ARV is highly resistant to the antiviral effects of IFN. However, the underlying mechanisms that enable ARV to block the IFN pathway remain unclear. In this study, we found that ectopic expression of ARV protein, σA, significantly inhibited the production of IFN-ß induced by melanoma-differentiation-associated gene 5 (MDA5) and poly(I·C). Knockdown of σA during ARV infection enhances the IFN-ß response and suppresses viral replication. ARV σA inhibited the MDA5-mediated IFN-ß activation by targeting interferon regulatory factor 7 (IRF7). Further studies demonstrated that σA interacts with IRF7, thereby blocking IRF7 dimerization and nuclear translocation, finally leading to the inhibition of IFN-ß production. These findings reveal a novel mechanism that allows ARV to evade host antiviral immunity. IMPORTANCE ARV, the causative agent of viral arthritis or tenosynovitis in chickens, has a significant economic impact as it results in poor weight gain and increased feed conversion ratios. The MDA5-mediated IFN-ß signal pathway plays an important role in host antiviral defense. Therefore, RNA viruses have developed mechanisms to counter this signaling pathway and successfully establish infection. However, the strategies adopted by ARV to block MDA5-IRF7 signaling remain unclear. In the current study, we demonstrated that ARV σA inhibits this pathway by binding to IRF7, which blocked IRF7 dimerization and nuclear translocation. Our findings may provide insights into how avian reovirus counteracts the innate antiviral immunity of the host to ensure viral replication.

Role of the OTUB1/IRF7/NOX4 axis in oxidative stress injury and inflammatory responses in mice with Parkinson's disease.

BACKGROUND: Parkinson's disease (PD) is one of the most devastating neurodegenerative disorders and is associated with oxidative stress injury (OSI) and inflammatory responses. This study sought to investigate the mechanism of ovarian tumour domain-containing ubiquitin aldehyde binding 1 (OTUB1) in OSI and inflammatory responses in PD, providing a theoretical foundation for PD treatment. METHODS: The PD mouse model was established by an intraperitoneal injection of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, followed by behavioural tests, observation of brain pathological changes, and quantification of inflammatory (TNF-α, IL-1ß, and IL-10) and OS (ROS, SOD, and MDA) factors. Next, the expression levels of OTUB1, interferon regulatory factor 7 (IRF7), and NADPH oxidase 4 (NOX4) levels were determined by real-time quantitative polymerase chain reaction and western blot assay, the binding of OTUB1 to IRF7 was analysed by co-immunoprecipitation, and the ubiquitination level of IRF7 and the enrichment and binding of IRF7 and the NOX4 promoter were measured by chromatin immunoprecipitation and dual-luciferase assays. Afterwards, rescue experiments were performed with IRF7 or NOX4 overexpression in OTUB1 knockout PD mice. RESULTS: OTUB1 was upregulated in brain tissues of PD mice. Inhibition of OTUB1 alleviated PD progression, OSI, and inflammatory responses. OTUB1 stabilized IRF7 through deubiquitination, and IRF7 bound to the NOX4 promoter to promote NOX4 expression. IRF7 or NOX4 overexpression reversed the effects of silencing OTUB1 on OSI and inflammatory responses in PD mice. CONCLUSION: OTUB1-mediated deubiquitination stabilized IRF7 and upregulated NOX4 expression, thereby promoting OSI and inflammatory responses in PD mice.