IFN Response Research Articles

Apoptotic Caspases Suppress Expression of Endogenous Retroviruses in HPV31+ Cells That Are Associated with Activation of an Innate Immune Response

Avoidance of an immune response is critical to completion of the human papillomavirus (HPV) life cycle, which occurs in the stratified epithelium and is linked to epithelial differentiation. We previously demonstrated that high-risk HPVs use apoptotic caspases to suppress an antiviral innate immune response during the productive phase of the life cycle. We found that caspase-8 and caspase-3 suppress a type I IFN-β and type III IFN-λ response by disabling the MDA5/MAVS double-stranded RNA (dsRNA) sensing pathway, indicating that immunogenic RNAs increase upon differentiation in HPV+ cells. In this study, we demonstrate that caspase inhibition results in aberrant transcription of a subset of endogenous retroviruses (ERVs) that have been shown to activate an IFN response through dsRNA-sensing pathways. We show that the increase in ERV transcription is accompanied by an enrichment in dsRNA formation. Additionally, we demonstrate that the robust increase in ERV expression requires activation of the JAK/STAT-signaling pathway, indicating that this subset of ERVs is IFN-inducible. Overall, these results suggest a model by which caspase activity blocks the reactivation of ERVs through the JAK/STAT pathway, protecting HPV+ cells from an increase in immunogenic dsRNAs that otherwise would trigger an IFN response that inhibits productive viral replication.

Human genital dendritic cell heterogeneity confers differential rapid response to HIV-1 exposure

Dendritic cells (DCs) play critical roles in HIV pathogenesis and require further investigation in the female genital tract, a main portal of entry for HIV infection. Here we characterized genital DC populations at the single cell level and how DC subsets respond to HIV immediately following exposure. We found that the genital CD11c+HLA-DR+ myeloid population contains three DC subsets (CD1c+ DC2s, CD14+ monocyte-derived DCs and CD14+CD1c+ DC3s) and two monocyte/macrophage populations with distinct functional and phenotypic properties during homeostasis. Following HIV exposure, the antiviral response was dominated by DCs’ rapid secretory response, activation of non-classical inflammatory pathways and host restriction factors. Further, we uncovered subset-specific differences in anti-HIV responses. CD14+ DCs were the main population activated by HIV and mediated the secretory antimicrobial response, while CD1c+ DC2s activated inflammasome pathways and IFN responses. Identification of subset-specific responses to HIV immediately after exposure could aid targeted strategies to prevent HIV infection.

Immunomodulatory effects of trastuzumab deruxtecan through the cGAS-STING pathway in gastric cancer cells

Although the efficacy of trastuzumab deruxtecan (T-DXd) against HER2-positive gastric cancers (GCs) has driven its clinical application, the precise mechanisms governing its immunomodulatory role remain unclear. In this study, we examined the immune-related mechanisms of action of T-DXd in GC cells. T-DXd exhibited potent antitumor effects in GC cells across diverse HER2 expression levels by inducing DNA damage and apoptosis. Activation of the DNA damage response by T-DXd led to increased PD-L1 expression. RNA-Seq analysis revealed that T-DXd modulated immune-related pathways, resulting in the upregulation of genes associated with inflammation and IFN signaling. Importantly, T-DXd activated the cGAS-STING pathway, inducing an IFN-I response in HER2-positive GC cells. Furthermore, T-DXd activated dendritic cells via the cancer cell-intrinsic cGAS-STING-IFN axis and enhanced PBMC-mediated tumor cell killing by activating CD8+ T cells. These findings provide valuable insights into the role of the cytosolic DNA sensing pathway in the action of T-DXd and offer a compelling rationale for combining T-DXd with immune checkpoint blockade therapies in GC treatment.

Pseudorabies virus infection triggers mitophagy to dampen the interferon response and promote viral replication.

Pseudorabies virus (PRV) utilizes multiple strategies to inhibit type I interferon (IFN-I) production and signaling to achieve innate immune evasion. Among several other functions, mitochondria serve as a crucial immune hub in the initiation of innate antiviral responses. It is currently unknown whether PRV inhibits innate immune responses by manipulating mitochondria. In this study, we found that PRV infection damages mitochondrial structure and function, as shown by mitochondrial membrane potential depolarization, reduction in mitochondrial numbers, and an imbalance in mitochondrial dynamics. In addition, PRV infection triggered PINK1-Parkin-mediated mitophagy to eliminate the impaired mitochondria, which resulted in a suppression of IFN-I production, thereby promoting viral replication. Furthermore, we found that mitophagy resulted in the degradation of the mitochondrial antiviral signaling protein, which is located on the mitochondrial outer membrane. In conclusion, the data of the current study indicate that PRV-induced mitophagy represents a previously uncharacterized PRV evasion mechanism of the IFN-I response, thereby promoting virus replication.IMPORTANCEPseudorabies virus (PRV), a pathogen that induces different disease symptoms and is often fatal in domestic animals and wildlife, has caused great economic losses to the swine industry. Since 2011, different PRV variant strains have emerged in Asia, against which current commercial vaccines may not always provide optimal protection in pigs. In addition, there are indications that some of these PRV variant strains may sporadically infect people. In the current study, we found that PRV infection causes mitochondria injury. This is associated with the induction of mitophagy to eliminate the damaged mitochondria, which results in suppressed antiviral interferon production and signaling. Hence, our study reveals a novel mechanism that is used by PRV to antagonize the antiviral host immune response, providing a theoretical basis that may contribute to the research toward and development of new vaccines and antiviral drugs.

Toxoplasma gondii ROP5 Enhances Type I IFN Responses by Promoting Ubiquitination of STING.

Toxoplasma gondii is a widely spread opportunistic pathogen that can infect nearly all warm-blooded vertebrates and cause serious toxoplasmosis in immunosuppressed animals and patients. However, the relationship between the host's innate immune system and effector proteins is poorly understood, particularly with regard to how effectors antagonize cGAS-STING signaling during T. gondii infection. In this study, the ROP5 from the PRU strain of T. gondii was found to promote cGAS-STING-mediated immune responses. Mechanistically, ROP5 interacted with STING through predicted domain 2 and modulated cGAS-STING signaling in a predicted domain 3-dependent manner. Additionally, ROP5 strengthened cGAS-STING signaling by enhancing the K63-linked ubiquitination of STING. Consistently, ROP5 deficient PRU (PRUΔROP5) induced fewer type I IFN-related immune responses and replicated faster than the parental strain in RAW264.7 cells. Taken together, this study provides new insights into the mechanism by which ROP5 regulates T. gondii infection and provides new clues for strategies to prevent and control toxoplasmosis.

Systemic Sclerosis dermal fibroblast exosomes trigger a Type 1 interferon response in keratinocytes through the TBK/JAK/STAT signalling axis.

Activation of Type I IFN response has been shown to correlates with disease activity in systemic sclerosis. It is currently unknown whether the tissue-specific Type I IFN activation is a consequence of the response observed in blood or rather its source. Exosomes from SSc fibroblasts were recently shown to activate macrophages in vitro. Here, we aimed to determine the source of Type I IFN signature in SSc skin biopsies and the potential role of exosomes from SSc dermal fibroblasts in the process. Skin biopsies were obtained from healthy and SSc patients' forearms and processed for dermal fibroblasts and keratinocytes. Exosomes were isolated from healthy and SSc dermal fibroblast supernatants by ultracentrifugation and added to human skin keratinocytes. Keratinocyte transcriptome was analysed by RNA-seq analysis. TANK-binding kinase (TBK) and JAK were inhibited using a small molecule inhibitor (GSK8612) and Tofacitinib, respectively. SSc skin biopsies showed highest levels of Type I IFN response in the epidermal layer. RNA-seq analysis of keratinocytes transcriptome following exposure to dermal fibroblast exosomes showed strong upregulation of IFN signature genes induced by SSc exosomes compared to Healthy control. Inhibition of TBK or JAK activity suppressed the upregulation of the IFN signature induced by SSc exosomes. IFN activation of SSc keratinocytes is dependent on their crosstalk with dermal fibroblasts and inducible by extracellular exosomes. Our data indicates that SSc fibroblasts exosomes contributes to theType I IFN activation in SSc skin through activation of pattern recognition receptors upstream of TBK.

TMT-based quantitative proteomic analysis of IBDV-infected CEF cells reveals a favorable role of chicken IRF10 in IBDV replication via suppressing type-I interferon expression

Infectious bursal disease (IBD) is an acute, highly contagious disease caused by infectious bursal disease virus (IBDV), causing huge economic losses to the poultry industry worldwide. Currently, the emerging variant strains of IBDV and new recombinants in the field are circulating in many countries and poses severe threats to the development of poultry industry. Elucidation of the pathogenesis of IBDV infection will be of great help to the development of vaccines for control of IBDV infection. In this study, liquid chromatography tandem-mass spectrometry (LC–MS/MS) combined with tandem mass tag (TMT) labeling was performed to determine the expressions of nucleus proteins in IBDV-infected chicken embryonic fibroblast (CEF) cells 24 h post-infection (hpi). Our data show that a total of 236 nucleus proteins were differentially expressed in IBDV-infected cells vs mock-infected controls, and that among those proteins, 171 were significantly upregulated while 65 downregulated. Bioinformatics analysis reveals that the differentially expressed proteins (DEPs) were mainly involved in immune response, DNA replication, mismatch repair, and RIG-I-like receptor (RLR) signaling. Consistently, the expression of ten selected upregulated genes (IRF10, IRF7, IRF1, STAT1, ATF3, GTF3A, CSRP3, RARB, BASP1, and NF-κB1) markedly increased as examined by quantitative real‐time PCR (qRT-PCR). Furthermore, the expression of IRF10 was upregulated both in the cytoplasm and nucleus of DF-1 cells as examined by Western Blot. Moreover, knockdown of IRF10 remarkably inhibited IBDV replication via promoting IFN-I response, and overexpression of IRF10 significantly suppressed type I interferon and ISGs expression in both mock and IBDV-infected cells, suggesting that IRF10 serve as a negative regulator for host antiviral response. These results provide clues to further investigation into host–IBDV interactions and the underlying mechanisms of IBDV infection.

Elucidating the power of arginine restriction: taming type I interferon response in breast cancer via selective autophagy

BackgroundType I interferons (IFN-I) are potent alarm factors that initiate cancer cell elimination within tumors by the immune system. This critical immune response is often suppressed in aggressive tumors, thereby facilitating cancer immune escape and unfavorable patient outcome. The mechanisms underpinning IFN-I suppression in tumors are incompletely understood. Arginase-1 (ARG1)-expressing immune cells that infiltrate tumors can restrict arginine availability by ARG1-mediated arginine degradation. We hypothesized that arginine restriction suppresses the IFN-I response in tumors.MethodsComprehensive, unbiased open approach omics analyses, various in vitro techniques, including microscopy, qPCR, immunoblotting, knock-down experiments, and flow cytometry were employed, as well as ex vivo analysis of tumor tissue from mice. Several functional bioassays were utilized to assess metabolic functions and autophagy activity in cancer cells.ResultsArginine restriction potently induced expression of selective autophagy receptors, enhanced bulk and selective autophagy and strongly suppressed the IFN-I response in cancer cells in an autophagy-dependent manner.ConclusionOur study proposes a mechanism for how tumor-infiltrating immune cells can promote cancer immune escape by dampening the IFN-I response. We suggest ARG1 and autophagy as putative therapeutic targets to activate the IFN-I response in tumors.

7820 Immune system adaptation during gender-affirming testosterone treatment

Abstract Disclosure: T. Lakshmikanth: None. C. Consiglio: None. F. Sardh: None. R. Forlin: None. J. Wang: None. Z. Tan: None. H. Barencilla: None. L. Rodriguez: None. J. Sugrue: None. P. Noori: None. M. Ivanchenko: None. L. Piñero Páez: None. L. Gonzalez: None. C. Habimana Mugabo: None. A. Johnsson: None. H. Ryberg: None. Å. Hallgren: None. C. Pou: None. Y. Chen: None. J. Mikeš: None. A. James: None. P.M. Dahlqvist: None. J. Wahlberg Hughes: None. A. Hagelin: None. M. Holmberg: None. M. Degerblad: None. M. Isaksson: None. D. Duffy: None. O. Kampe: None. N. Landegren: None. P. Brodin: None. Immune system adaptation during gender-affirming testosterone treatment Infectious, inflammatory and autoimmune conditions present differently in males and females. Following SARS-CoV-2 infection, male sex is associated with increased risk of death, while female sex is associated with increased risk of the postinfectious disorder, long COVID. Similar trends are seen in other infections. Female immune responses to vaccines are typically stronger, and adverse reactions are more frequent, like most autoimmune diseases. Immunological sex-differences stem from genetic, hormonal and behavioural factors but their relative importance is poorly understood. To understand the consequences of changing sex-hormones in vivo, we performed longitudinal, systems-level analyses in 22 adults, assigned female at birth, and undergoing gender-affirming testosterone treatment (trans-men). We find that sex hormones modulate a cross-regulation axis of type-I interferon (IFN-I) and TNFα in humans. This is mediated by a reduced frequency of plasmacytoid dendritic cells (pDC), and functional attenuation of IFN-I responses in both pDCs and monocytes. Conversely, testosterone potentiates monocyte responses to lipopolysaccharide (LPS) leading to increased TNFα, IL-6 and IL-15 production and downstream epigenetic opening of NFκB regulated genes and potentiation of IFNγ responses, primarily by NK cells. IFNγ in turn feeds back onto monocytes leading to upregulation of SLAMF7 and further enhanced TNFα responses by myeloid cells. These results are corroborated by sex-divergent responses in multiple public datasets and collectively illustrate the dynamic recalibration of human immune systems by sex hormones with implications for individuals undergoing gender-affirming hormone therapy, but also better understanding of divergent responses to infection, vaccines and self-antigens in cisgender individuals. Presentation: 6/2/2024

7820 Immune system adaptation during gender-affirming testosterone treatment

Abstract Disclosure: T. Lakshmikanth: None. C. Consiglio: None. F. Sardh: None. R. Forlin: None. J. Wang: None. Z. Tan: None. H. Barencilla: None. L. Rodriguez: None. J. Sugrue: None. P. Noori: None. M. Ivanchenko: None. L. Piñero Páez: None. L. Gonzalez: None. C. Habimana Mugabo: None. A. Johnsson: None. H. Ryberg: None. Å. Hallgren: None. C. Pou: None. Y. Chen: None. J. Mikeš: None. A. James: None. P.M. Dahlqvist: None. J. Wahlberg Hughes: None. A. Hagelin: None. M. Holmberg: None. M. Degerblad: None. M. Isaksson: None. D. Duffy: None. O. Kampe: None. N. Landegren: None. P. Brodin: None. Infectious, inflammatory and autoimmune conditions present differently in males and females. Following SARS-CoV-2 infection, male sex is associated with increased risk of death, while female sex is associated with increased risk of the postinfectious disorder, long COVID. Similar trends are seen in other infections. Female immune responses to vaccines are typically stronger, and adverse reactions are more frequent, like most autoimmune diseases. Immunological sex-differences stem from genetic, hormonal and behavioural factors but their relative importance is poorly understood. To understand the consequences of changing sex-hormones in vivo, we performed longitudinal, systems-level analyses in 22 adults, assigned female at birth, and undergoing gender-affirming testosterone treatment (trans-men). We find that sex hormones modulate a cross-regulation axis of type-I interferon (IFN-I) and TNFα in humans. This is mediated by a reduced frequency of plasmacytoid dendritic cells (pDC), and functional attenuation of IFN-I responses in both pDCs and monocytes. Conversely, testosterone potentiates monocyte responses to lipopolysaccharide (LPS) leading to increased TNFα, IL-6 and IL-15 production and downstream epigenetic opening of NFκB regulated genes and potentiation of IFNγ responses, primarily by NK cells. IFNγ in turn feeds back onto monocytes leading to upregulation of SLAMF7 and further enhanced TNFα responses by myeloid cells. These results are corroborated by sex-divergent responses in multiple public datasets and collectively illustrate the dynamic recalibration of human immune systems by sex hormones with implications for individuals undergoing gender-affirming hormone therapy, but also better understanding of divergent responses to infection, vaccines and self-antigens in cisgender individuals. Presentation: 6/2/2024

Immunometabolic Mechanisms of LANCL2 in CD4+ T Cells and Phagocytes Provide Protection from Systemic Lupus Erythematosus.

Lanthionine synthetase C-like 2 (LANCL2) is an immunoregulatory therapeutic target for autoimmune diseases. NIM-1324 is an investigational new drug aimed at addressing the unmet clinical needs of patients with systemic lupus erythematosus (SLE) by targeting the LANCL2 immunometabolic pathway. In R848 and bm12 adoptive transfer models of systemic inflammation that share pathologies with SLE, Lancl2-/- mice experienced greater mortality, increased spleen weight, and reduced CD25hi FOXP3+ CD4+ regulatory T cells compared with the wild type. Conversely, treatment with NIM-1324 in the wild type increased CD25hi FOXP3+ regulatory T cells while reducing inflammatory IL-17+ and IL-21+ CD4+ T cell subsets in the spleen. In traditional mouse models of SLE (NZB/W F1 and MRL/lpr), oral treatment with NIM-1324 protected against weight loss and proteinuria, decreased anti-dsDNA titers, and provided similar changes to the CD4+ T cell compartment in the spleen. The pharmacological activation of LANCL2 by NIM-1324 rescued hypocomplementemia, reduced kidney histopathological scores, and decreased blood IFN response genes and inflammatory cytokines. The loss of LANCL2 in phagocytes impairs phagosome processing, leading to increased uptake of material and inflammatory cytokine production, yet decreased markers of endosomal maturation, phagosome turnover, and lysozyme activity. Treatment with NIM-1324 increases metabolic and lysozyme activity in the phagosome, providing support for increased markers of early phagosome function. This efficacy translated to human PBMCs from patients with SLE, because ex vivo treatment with NIM-1324 resulted in reduced levels of IFN-α, IL-6, and IL-8. Consequently, the activation of LANCL2 effectively modulates CD4+ T cell differentiation and phagocyte activation, supporting immune tolerance in SLE.

160 (PB148): Targeting AXL kinase with Bemcentinib to enhance Type 1 IFN response and sensitize tumors to chemo-immunotherapy

160 (PB148): Targeting AXL kinase with Bemcentinib to enhance Type 1 IFN response and sensitize tumors to chemo-immunotherapy

Identification and RT-qPCR Validation of Biomarkers Based on Butyrate Metabolism-Related Genes to Predict Recurrent Miscarriage.

To date, the cause of recurrent miscarriage (RM) in at least 50% of patients remains unknown. However, no study has explored the correlation between butyrate metabolism-related genes (BMRGs) and RM. RM-related datasets (GSE165004, GSE111974, GSE73025, and GSE179996) were obtained from the Gene Expression Omnibus (GEO) database. First, 595 differentially expressed genes (DEGs) were identified between the RM and control samples in GSE165004. Subsequently, 213 differentially expressed BMRGs (DE-BMRGs) were identified by considering the intersection of DEGs with BMRGs. The protein-protein interaction (PPI)network of DE-BMRGs contained 156 nodes and 250 edges, and a key module was obtained. In total, four biomarkers (ACTR2, ANXA2, PFN1, and OAS1) were acquired through least absolute shrinkage and selection operator (LASSO), support vector machine-recursive feature elimination (SVM-RFE), and random forest (RF). Immune analysis revealed two immune cells and three immune-related gene sets that were significantly different between the RM and control groups, namely, T helper cells, regulatory T cells (Treg), MHC class I, parainflammation, and type I IFN response. In addition, a TF-mRNA network based on the top 100 nodes ranked in the order of connectivity was created, including 100 nodes and 253 edges, such as MTERF2-ACTR2, NKX23-PFN1, STAT1-OAS1, and SP100-ANXA2. Finally, 3 drugs (withaferin A, N-ethylmaleimide, and etoposide) were predicted to interact with 2 biomarkers (ANXA2 and ACTR2). Eventually, ANXA2 and OAS1 were significantly downregulated, and PFN1 was markedly overexpressed in the RM group, as determined by reverse transcription quantitative polymerase chain reaction (RT-qPCR). Our findings authenticated four butyrate metabolism-related biomarkers for the diagnosis of RM, providing a scientific reference for further studies on RM treatment.

NOD2-mediated dual negative regulation of inflammatory responses triggered by TLRs in the gastrointestinal tract.

Loss-of-function mutations in nucleotide-binding oligomerization domain 2 (NOD2) constitute the primary risk factors for Crohn's disease. NOD2 is an intracellular sensor for muramyl dipeptide (MDP), a small molecule derived from the peptidoglycan layer of bacterial cell wall. Although NOD2 is involved in host immune responses, much attention has been paid to the involvement of NOD2 in the maintenance of intestinal homeostasis. Despite the fact that the proinflammatory cytokine and chemokine responses induced by NOD2 activation alone are weaker than those induced by toll-like receptors (TLRs), NOD2 plays a crucial role in host defense against invading pathogens and in the regulation of immune responses. Recent studies have highlighted the importance of negative regulatory functions of NOD2 in TLRs-mediated proinflammatory cytokine responses. MDP-mediated activation of NOD2 induces interferon regulatory factor 4 (IRF4) expression, thereby suppressing nuclear factor-κB-dependent colitogenic cytokine responses through the inhibition of Lys(K)63-linked polyubiquitination on receptor-interacting serine/threonine protein kinase 2. MDP-mediated activation of NOD2 also downregulates TLR9-induced type I IFN responses by inhibiting the K63-linked polyubiquitination of TNF receptor-associated factor 3 via deubiquitinating enzyme A (DUBA) expression. Thus, NOD2 exerts dual negative regulation of TLRs-mediated proinflammatory cytokine and type I IFN responses by inducing the expression of IRF4 and DUBA, respectively. In this review, we summarize the molecular mechanisms whereby NOD2 activation suppresses TLRs-mediated proinflammatory and type I IFN responses. In addition, we discuss the clinical relevance of the NOD2-mediated negative regulation of TLRs in inflammatory bowel disease.

Peripheral Blood IFN Responses to Toll-Like Receptor 1/2 Signaling Associate with Longer Survival in Men with Metastatic Prostate Cancer Treated with Sipuleucel-T.

The identification of factors that determine successful cancer immunotherapy, particularly in refractory tumor types like mCRPC, is urgently needed: both to identify patients that may benefit from such therapies and to uncover routes to sensitize patients with cancer to immunotherapy. Our work links functional peripheral immune responses with race and survival after cellular immunotherapy in men with mCRPC.

A sensitive assay for measuring whole-blood responses to type I IFNs

Human inborn errors of the type I IFN response pathway and auto-Abs neutralizing IFN-α, -β, and/or -ω can underlie severe viral illnesses. We report a simple assay for the detection of both types of condition. We stimulate whole blood from healthy individuals and patients with either inborn errors of type I IFN immunity or auto-Abs against type I IFNs with glycosylated human IFN-α2, -β, or -ω. As controls, we add a monoclonal antibody (mAb) blocking the type I IFN receptors and stimulated blood with IFN-γ (type II IFN). Of the molecules we test, IP-10 (encoded by the interferon-stimulated gene (ISG) CXCL10) is the molecule most strongly induced by type I and type II IFNs in the whole blood of healthy donors in an ELISA-like assay. In patients with inherited IFNAR1, IFNAR2, TYK2, or IRF9 deficiency, IP-10 is induced only by IFN-γ, whereas, in those with auto-Abs neutralizing specific type I IFNs, IP-10 is also induced by the type I IFNs not neutralized by the auto-Abs. The measurement of type I and type II IFN-dependent IP-10 induction therefore constitutes a simple procedure for detecting rare inborn errors of the type I IFN response pathway and more common auto-Abs neutralizing type I IFNs.

Interferon lambda signaling in neutrophils enhances the pathogenesis of Bordetella pertussis infection

Abstract Interferon lambda plays diverse roles in bacterial infections. Previously, we showed that interferon lambda is induced in the lungs of Bordetella pertussis-infected adult mice and exacerbates inflammation. Here, we report that mice lacking the interferon lambda receptor 1 specifically on neutrophils (MRP8creIFNLR1fl/fl mice) exhibit reduced lung bacterial load and inflammation compared to wild-type mice during B. pertussis infection. In B. pertussis-infected wild-type mice, lung type I and III IFN responses were higher than in MRP8creIFNLR1fl/fl mice, correlating with increased lung inflammatory pathology. There was an increased proportion of interferon gamma-producing neutrophils in the lungs of MRP8creIFNLR1fl/fl mice compared to wild-type mice. IFNLR1−/− neutrophils incubated with B. pertussis exhibited higher killing compared to wild-type neutrophils. Treatment of wild-type neutrophils with interferon lambda further decreased their bacterial killing capacity and treatment of wild-type mice with interferon lambda increased lung bacterial loads. Contributing to the differential killing, we found that IFNLR1−/− neutrophils exhibit higher levels of reactive oxygen species, myeloperoxidase, matrix metalloproteinase-9 activity, neutrophil extracellular traps, and interferon gamma secretion than wild-type neutrophils, and inhibiting NADPH oxidase inhibited bacterial killing in IFNLR1−/− neutrophils. B. pertussis-induced interferon lambda secretion and IFNLR1 gene expression in mouse and human neutrophils and this was dependent on the bacterial virulence protein pertussis toxin. Pertussis toxin enhanced bacterial loads in wild type but not in MRP8creIFNLR1fl/fl or IFNLR1−/− mice. Thus, pertussis toxin disrupts neutrophil function by enhancing type III IFN signaling, which prevents neutrophils from effectively clearing B. pertussis during infection, leading to higher bacterial loads and exacerbation of lung inflammation.

Tissue Kallikrein-1 Suppresses Type I Interferon Responses and Reduces Depressive-Like Behavior in the MRL/lpr Lupus-Prone Mouse Model.

Excessive production and response to Type I interferons (IFNs) is a hallmark of systemic lupus erythematosus (SLE). Neuropsychiatric lupus (NPSLE) is a common manifestation of human SLE, with major depression as the most common presentation. Clinical studies have demonstrated that IFNα can cause depressive symptoms. We have shown that the kallikrein-kinin system (KKS) [comprised of kallikreins (Klks) and bradykinins] and angiotensin-converting enzyme inhibitors suppressed Type I IFN responses in dendritic cells from lupus-prone mice and human peripheral blood mononuclear cells. Tissue Klk genes are decreased in patients with lupus, and giving exogenous Klk1 ameliorated kidney pathology in mice. We retro-orbitally administered mouse klk1 gene-carrying adenovirus in the Murphy Roths Large lymphoproliferative (MRL/lpr) lupus-prone mice at early disease onset and analyzed immune responses and depressive-like behavior. Klk1 improved depressive-like behavior, suppressed interferon-responsive genes and neuroinflammation, and reduced plasma IFNα levels and proinflammatory cytokines. Klk1 also reduced IFNAR1 and JAK1 protein expression, important upstream molecules in Type I IFN signaling. Klk1 reduced bradykinin B1 receptor expression, which is known to induce proinflammatory response. Together, these findings suggest that Klk1 may be a potential therapeutic candidate to control IFNα production/responses and other inflammatory responses in SLE and NPSLE.

The regulatory functions of ESX-1 substrates, EspE and EspF, are separable from secretion.

Pathogenic mycobacteria are a significant global health burden. The ESX-1 secretion system is essential for mycobacterial pathogenesis. The secretion of ESX-1 substrates is required for phagosomal lysis, which allows the bacteria to enter the macrophage cytoplasm, induce a Type I IFN response, and spread to new host cells. EspE and EspF are dual-functioning ESX-1 substrates. Inside the mycobacterial cell, they regulate transcription of ESX-1-associated genes. Following secretion, EspE and EspF are essential for lytic activity. The link between EspE/F secretion and regulatory function has not been investigated. We investigated the relationship between EspE and EspF using molecular genetics in Mycobacterium marinum, a non-tuberculous mycobacterial species that serves as an established model for ESX-1 secretion and function in Mycobacterium tuberculosis. Our data support that EspE and EspF, which require each other for secretion, directly interact. The disruption of the predicted protein-protein interaction abrogates hemolytic activity and secretion but does not impact their gene regulatory activities in the mycobacterial cell. In addition, we predict a direct protein-protein interaction between the EsxA/EsxB heterodimer and EspF. Our data support that the EspF/EsxA interaction is also required for hemolytic activity and EspE secretion. Our study sheds light on the intricate molecular mechanisms governing the interactions between ESX-1 substrates, regulatory function, and ESX-1 secretion, moving the field forward.IMPORTANCETuberculosis (TB), caused by Mycobacterium tuberculosis, is a historical and pervasive disease responsible for millions of deaths annually. The rise of antibiotic and treatment-resistant TB, as well as the rise of infection by non-tuberculous mycobacterial species, calls for a better understanding of pathogenic mycobacteria. The ESX-1 secreted substrates, EspE and EspF, are required for mycobacterial virulence and may be responsible for phagosomal lysis. This study focuses on the mechanism of EspE and EspF secretion from the mycobacterial cell.

CREB-binding protein/P300 bromodomain inhibition reduces neutrophil accumulation and activates antitumor immunity in triple-negative breast cancer.

Tumor-associated neutrophils (TANs) have been shown to promote immunosuppression and tumor progression, and a high TAN frequency predicts poor prognosis in triple-negative breast cancer (TNBC). Dysregulation of CREB-binding protein (CBP)/P300 function has been observed with multiple cancer types. The bromodomain (BRD) of CBP/P300 has been shown to regulate its activity. In this study, we found that IACS-70654, a selective CBP/P300 BRD inhibitor, reduced TANs and inhibited the growth of neutrophil-enriched TNBC models. In the bone marrow, CBP/P300 BRD inhibition reduced the tumor-driven abnormal differentiation and proliferation of neutrophil progenitors. Inhibition of CBP/P300 BRD also stimulated the immune response by inducing an IFN response and MHCI expression in tumor cells and increasing tumor-infiltrated cytotoxic T cells. Moreover, IACS-70654 improved the response of a neutrophil-enriched TNBC model to docetaxel and immune checkpoint blockade. This provides a rationale for combining a CBP/P300 BRD inhibitor with standard-of-care therapies in future clinical trials for neutrophil-enriched TNBC.