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Oxidative stress induces E. coli aryl polyene expression, sensitizing the bacterial stress response and modulating the redox environment of innate immune cells.

UNLABELLED: Aryl polyenes (APEs) are specialized polyunsaturated outer membrane lipids that protect their producers from oxidative stress and contribute to biofilm formation. APEs are produced by an abundant biosynthetic gene cluster (BGC) family conserved across Gram-negative bacterial clades. The APE biosynthesis pathway involves 11 different enzymes and culminates in the attachment of APEs to an anchor molecule in the Gram-negative outer membrane. Unlike most other small molecule BGCs, the APE BGC does not contain a dedicated regulatory gene that controls the production of its metabolically costly compounds. Building from our prior observations of APEs' role in acute oxidative stress protection, we use a uropathogenic Escherichia coli (UPEC) strain to show that APE expression conveys a potential competitive advantage characterized by increased early-stage growth, sensitization of the bacterial oxidative stress response, and dampening of the redox stress of innate immune cells after in vitro infection. Our data indicate that APEs could act as a UPEC fitness factor, and in future work, we aim to study their contribution to overall bacterial pathogenicity and survival, as well as how APEs could facilitate the transition from an oxygen-poor environment, such as the gut, to the oxygen-rich environment of the urinary tract. IMPORTANCE: Bacterial pathogens use various mechanisms to achieve a competitive advantage under harsh conditions, such as during interactions with their host. We studied the function of aryl polyenes (APEs), specialized polyunsaturated fatty acids in the outer membrane, in the context of a uropathogenic E. coli strain. APE expression is induced by an oxidative environment and contributes to early-stage growth and sensitization of the oxidative stress response. Furthermore, APE-expressing E. coli dampen the intracellular oxidative milieu of target host phagocytes. These findings suggest a role for APEs as a fitness factor and create opportunities to study their in vivo function and explore them as a potential drug target.

Oxidative Stress

Epigenetic and metabolic reprogramming of innate immune cells establishes immunological memory in the Schistosomiasis vector snail Biomphalaria glabrata.

Innate immune memory enables non-vertebrates to mount faster and more effective immune responses upon re-exposure to a previously encountered pathogen, yet its cellular and molecular bases remain poorly understood. The freshwater snail Biomphalaria glabrata, intermediate host of the human parasite Schistosoma mansoni, provides a powerful model to investigate this phenomenon. Here, we show that innate immune memory in B. glabrata is carried by hemocytes and relies on profound metabolic and epigenetic reprogramming initiated during primary infection. Using an integrative multi-omics approach combining transcriptomics, chromatin accessibility profiling, whole-genome bisulfite sequencing and targeted metabolomics, we reveal that the first parasite encounter induces a stable rewiring of hemocyte metabolism and chromatin landscape. This reprogramming primes hemocytes for a massive and rapid transcriptional response upon secondary challenge, characterized by an immune shift toward highly specific humoral effector pathways. Metabolic analyses demonstrate an early switch toward aerobic glycolysis, altered tricarboxylic acid cycle activity and amino acid metabolism, consistent with a Warburg-like metabolic state previously described in vertebrate trained immunity. Notably, metabolic and epigenetic remodeling occurs primarily during the primary infection and remains stable upon secondary exposure, suggesting that immune memory is encoded prior to pathogen re-encounter. Together, our results identify conserved metabolic and epigenetic mechanisms underlying innate immune memory in a non-vertebrate host and provide direct evidence that hemocyte-mediated innate immune memory in B. glabrata shares core features with trained immunity described in vertebrates.

Animals

Ascites reprograms innate lymphoid immune cells in ovarian cancer by promoting ILC2 enrichment and dysfunctional NK-cell states.

BACKGROUND: High-grade serous ovarian cancer (HGSOC) is commonly accompanied by malignant ascites, a clinically relevant tumor niche that promotes immune evasion, metastasis, and treatment resistance. Although natural killer (NK)-cell dysfunction has been described in ovarian cancer, the broader innate lymphoid landscape of ascites and the mechanisms linking ascites-derived signals to innate immune suppression remain insufficiently resolved. METHODS: We performed single-cell RNA sequencing of NK/innate lymphoid cells from ovarian cancer ascites to define cellular heterogeneity and differentiation states. Functional assays assessed NK-cell cytotoxicity, degranulation, and receptor expression following exposure to patient-derived ascites, with or without transforming growth factor-β (TGF-β) receptor inhibition. Proteomic profiling was used to characterize the soluble ascites milieu, and clinical associations were examined for innate lymphoid subsets. RESULTS: Single-cell analysis identified eight transcriptionally distinct NK/innate lymphoid states, including cytotoxic, precursor, early-like, tolerant/immunoregulatory, regulatory, proinflammatory, and innate lymphoid populations. Ovarian cancer ascites was characterized by depletion of cytotoxic and precursor NK-cell states together with enrichment of early-like, tolerant, regulatory, pro-inflammatory, and innate lymphoid cell (ILC) populations. Trajectory analysis indicated impaired maturation toward terminally differentiated cytotoxic NK cells. Notably, ascites contained an expanded population of programmed cell death protein 1 (PD-1)+ ILC2s, which were more abundant in patients with shorter progression-free survival. In functional assays, short-term exposure of healthy donor NK cells to ascites suppressed degranulation and tumor-cell killing, reduced expression of activating receptors including NKp30 and DNAM-1, increased inhibitory receptor expression, and shifted NK cells toward a CD56highCD16low phenotype. Proteomic profiling supported a soluble milieu consistent with type 2 immune skewing and NK-cell suppression. Importantly, TGF-β receptor inhibition partially restored NK-cell activation and function in the presence of ascites. CONCLUSIONS: HGSOC ascites establishes a type 2-skewed immunoregulatory niche that coordinately drives NK cell dysfunction and PD-1+ ILC2 accumulation. The findings identify TGF-β-linked suppression and ascites-associated immune regulators as candidate immunotherapeutic vulnerabilities for restoring antitumor immunity in ovarian cancer.

Humans

Kmt2c and Kmt2d histone methyltransferase deficiencies compromise macrophage function.

Methylation of histone (H) 3 lysine (K) 4 (H3K4) has a well-established role in innate immune responses, but the contribution of H3K4 methyltransferases Kmt2c and Kmt2d in innate immunity is incompletely understood. Using conditional knockout mouse models, we investigated how Kmt2c- and Kmt2d-deficiencies affect innate immune cell function. Through functional, transcriptomic, and metabolic analyses, we delineate the consequences of disrupted epigenetic regulation on macrophage biology. Our findings reveal that loss of Kmt2c or Kmt2d in macrophages leads to impaired pro-inflammatory cytokine response and phagocytotic capacity, as well as skewed energy metabolism toward glycolysis, highlighting the critical role of H3K4 methylation-dependent chromatin regulation in shaping innate immune cell behavior. This study provides the first comprehensive characterization of innate immune system dysfunction in mouse models with conditional Kmt2c and Kmt2d deletions and offers mechanistic insight into how epigenetic regulators control fundamental immune processes.

Animals

Innate immune molecular landscape following controlled human influenza virus infection.

Viral infections can induce prolonged changes in innate immunity. Here, we use blood samples from a human influenza H3N2 challenge study (NCT03883113) to perform comprehensive multi-omics analyses. We detect remodeling of immune programs in circulating innate immune cells that persist after resolution of the infection. We find changes associated with suppressed inflammation, including decreased cytokine and AP-1 gene expression as well as decreased accessibility at AP-1 targets and interleukin-related gene promoter regions. We also find decreased histone deacetylase gene expression, increased MAP kinase gene expression, and increased accessibility at interferon-related gene promoter regions. Genes involved in inflammation and methylation remodeling show modulation of gene-chromatin site regulatory circuit activity. These results reveal a coordinated rewiring of the molecular landscape in innate immune cells induced by mild influenza virus infection.

Humans

Clonal stochasticity in early NK cell response to mouse cytomegalovirus is generated by mature subsets of varying proliferative ability.

Natural killer (NK) cells are classically defined as innate immune cells, but experiments show that mouse cytomegalovirus (MCMV) infection in C57BL/6 mice can cause NK cells to undergo antigen-specific proliferation and memory formation, similar to adaptive CD8+ T cells. One shared behavior between CD8+ T cells and NK cells is clonal expansion, where a single stimulated cell proliferates rapidly to form a diverse population of cells. For example, clones derived from single cells are most abundant during expansion when they are primarily CD27- for NK cells and CD62L- for T cells, phenotypes derived from precursor CD27+ and CD62L + cells, respectively. Here we determined the mechanistic rules involving proliferation, cell death, and differentiation of endogenous and adoptively transferred NK cells in the expansion phase of the response to MCMV infection. We found that the interplay between cell proliferation and cell death of mature CD27- NK cells and a highly proliferative CD27-Ly6C- mature subtype and intrinsic stochastic fluctuations in these processes play key roles in regulating the heterogeneity and population of the NK cell subtypes. Furthermore, we estimate rates for maturation of endogenous NK cells in homeostasis and in MCMV infection and found that only NK cell growth rates, and not differentiation rates, are appreciably increased by MCMV. Taken together, these results quantify the differences between the kinetics of NK cell antigen-specific expansion from that of CD8+T cells and unique mechanisms that give rise to the observed heterogeneity in NK cell clones generated from single NK cells in the expansion phase.

Animals

Rare epigenetic alterations are conserved across hematopoietic differentiation stages after mycobacterial infection.

Infection leads to durable cell-autonomous changes in hematopoietic stem and progenitor cells (HSPCs), resulting in production of innate immune cells with heightened immunity. The mechanisms underlying this phenomenon, termed central trained immunity, remain poorly understood. We hypothesized that infection induces histone modifications leading to changes in chromatin accessibility that are conserved during differentiation from HSPCs to myeloid progenitors and monocytes. We conducted genome-wide surveillance of histone marks H3K27ac and H3K4me3 and chromatin accessibility in hematopoietic stem cells, multipotent progenitor 3, granulocyte-monocyte progenitors, and monocytes and macrophages of naive and Mycobacterium avium-infected mice. IFN signaling pathways and related transcription factor binding motifs including IRFs, NF-κB, and CEBP showed increased activating histone marks and chromatin accessibility across cell types. However, histone marks and increased chromatin accessibility were conserved at only a few loci, notably Irf1 and Gbp6. Knock out of IRF1 disrupted enhanced mitochondrial respiration and bacterial killing in human monocyte cell lines, while GBP6-KO monocyte cell lines showed dysregulated mitochondrial respiration. In summary, this study identifies IRF1 and GBP6 as 2 key loci at which infection-induced systemic inflammation leads to epigenetic changes that are conserved from HSPCs to downstream monocytes, providing a mechanistic avenue for central trained immunity.

Animals

Programmed cell death-1: from a T-cell immune checkpoint to a regulator of Natural Killer cell biology.

Programmed cell death protein 1 (PD-1, CD279) is a pivotal inhibitory immune checkpoint receptor that plays a central role in maintaining immune homeostasis and peripheral tolerance. Originally characterized as a negative regulator of T-cell activation, PD-1 limits excessive immune responses and prevents autoimmunity, while its sustained expression under conditions of chronic antigen stimulation contributes to T-cell dysfunction and exhaustion. The discovery that blockade of the PD-1 pathway can restore anti-tumor immunity has revolutionized cancer therapy and established immune checkpoint inhibition as a cornerstone of modern oncology. Although PD-1 has traditionally been viewed as a key regulator of adaptive immunity, accumulating evidence indicates that its biological functions extend beyond T cells. In recent years, PD-1 expression has been identified in several innate immune cell populations, particularly Natural Killer (NK) cells, where it has emerged as an important modulator of effector functions, cytokine production, metabolic fitness, and antitumor activity. These findings have challenged the classical view of PD-1 biology and revealed unexpected similarities between NK-cell dysfunction and the exhausted phenotype described in chronically stimulated T cells. In the tumor microenvironment, PD-1 expression on NK cells has been associated with impaired cytotoxicity and reduced immune surveillance, suggesting that NK cells may also represent relevant targets of PD-1-mediated immunosuppression. At the same time, the mechanisms regulating PD-1 expression and signaling in NK cells appear to differ, at least in part, from those operating in T lymphocytes, highlighting the complexity of this pathway across distinct immune cell subsets. In this review, we summarize the current knowledge of PD-1 biology, from its established role in T-cell regulation to its emerging functions in NK cells. We discuss the molecular mechanisms governing PD-1 expression and signaling, its contribution to immune dysfunction in cancer and chronic diseases, and the potential implications of targeting the PD-1 axis to enhance both adaptive and innate antitumor immunity.

Natural Killer (NK) cells

Expression of intron-containing HIV-1 RNA induces NLRP1 inflammasome activation in myeloid cells.

Despite the success of antiretroviral therapy in suppressing plasma viremia in people living with human immunodeficiency virus type-1 (HIV-1), persistent viral RNA expression in tissue reservoirs is observed and can contribute to HIV-1-induced immunopathology and comorbidities. Infection of long-lived innate immune cells, such as tissue-resident macrophages and microglia may contribute to persistent viral RNA production and chronic inflammation. We recently reported that de novo cytoplasmic expression of HIV-1 intron-containing RNA (icRNA) in macrophages and microglia leads to MDA5 and MAVS-dependent innate immune sensing and induction of type I IFN responses, demonstrating that HIV icRNA is a pathogen-associated molecular pattern (PAMP). In this report, we show that cytoplasmic expression of HIV-1 icRNA also induces NLRP1 inflammasome activation and IL-1β secretion in macrophages and microglia in an RLR- and endosomal TLR-independent manner. Infection of both macrophages and microglia with either replication-competent or single-cycle HIV-1 induced IL-1β secretion, which was attenuated when cytoplasmic expression of viral icRNA was prevented. While IL-1β secretion was blocked by treatment with caspase-1 inhibitors or knockdown of NLRP1 or caspase-1 expression in HIV-infected macrophages, overexpression of NLRP1 significantly enhanced IL-1β secretion in an HIV-icRNA-dependent manner. Immunoprecipitation analysis revealed interaction of HIV-1 icRNA, but not multiply-spliced HIV-1 RNA, with NLRP1, suggesting that HIV-1 icRNA sensing by NLRP1 is sufficient to trigger inflammasome activation. Together, these findings reveal a pathway of NLRP1 inflammasome activation induced by de novo expressed HIV icRNA in HIV-infected myeloid cells.

HIV-1

Integrin-Linked Kinases 1, 4, and 5 participate in cell wall-mediated innate immunity to leaf and root pathogens.

The cell wall integrity (CWI) pathway is triggered by plasma membrane-localized receptors in plant cells and serves to orchestrate responses to cell wall damage by initiating compensatory changes under stressful environments. The essential role of CWI maintenance as part of plants' interactions with pests or pathogens and during growth is well known. Nevertheless, CWI pathways remain to be fully characterized. Here, we show that altered Integrin-Linked Kinase 1 (ILK1) expression causes widespread defects in the transcriptional program activated by the bacterial elicitor flg22, primarily in genes associated with cell wall integrity and immunity. These transcriptional deficiencies are recapitulated in mutant lines with altered ILK4 or ILK5 expression. Analysis of molecular and cellular defenses in ilk mutants revealed reduced callose accumulation in leaves treated with bacterial (elf18) and plant (pep1) elicitors and increased pathogen susceptibility. Histochemical analysis of cell-wall-associated staining across diverse cells and organs of ilk mutants revealed modified lignin-associated patterns in the root xylem and altered calcofluor staining patterns in the seed coat. All ilk mutants exhibited altered root morphology due to mechano-touch and high-NaCl stress. Based on these results, we propose that ILKs contribute to pathways connecting elicitor-triggered immune signaling with cell-wall-associated stress responses and that ILK-related defense functions may extend to the cotton root-nematode interaction, while the mechanism remains to be elucidated.

Cell Wall

The TRIM-cancer paradox: BCG as a programmable vaccine platform and a mechanistic probe for rational immunotherapy design.

BCG, a first-generation live vaccine, is being reconsidered as an immunological platform. Interest in its heterologous protection intensified during the pandemic. However, large-scale clinical trials revealed inconsistencies in the efficacy of native BCG. This review argues that BCG's main value lies in its potential as a modifiable vector platform and in its ability to reveal tractable molecular pathways for therapeutic design. This review summarizes the molecular basis of BCG-induced trained immunity (TRIM), focusing on PRR-driven signaling, metabolic rewiring, and epigenetic remodeling in innate immune cells and hematopoietic progenitors. It also maps their convergence with pathways that sustain pro-tumorigenic inflammation. The original conceptual paradigm of the "TRIM-Cancer Paradox" is presented. This paradigm posits that the same innate immune circuits that mediate protective heterologous responses can drive tumor-promoting inflammation and immune escape under conditions of chronic dysregulation. Recombinant BCG (rBCG) is further analyzed as a strategy to rationally amplify or redirect these circuits, the current clinical landscape of BCG-based interventions across various diseases and oncological malignancies is highlighted, and specific molecular nodes that could be exploited to increase the precision, efficacy, and safety of rBCG-based therapies are identified. Overall, this review proposes BCG a programmable immunological platform and to use the TRIM-Cancer Paradox as a novel design principle for next-generation rBCG platforms that transcend traditional vaccinology and cancer immunotherapy applications.

Humans

In vivo vitamin D target genes interconnect key signaling pathways of innate immunity.

The vitamin D3 metabolite 1,25-dihydroxyvitamin D3 (1,25(OH)2D3), its nuclear receptor VDR (vitamin D receptor) and hundreds of their target genes are not only key regulators of calcium homeostasis, but also important modulators of the immune system. Innate immune cells like monocytes use VDR for efficient differentiation and are very responsive to vitamin D. So far, most information on the gene regulatory function of vitamin D and its physiological impact had been obtained from in vitro studies using supraphysiological doses of 1,25(OH)2D3. Therefore, medical experiments like the study VitDHiD (NCT03537027), where 25 healthy individuals were supplemented once with a vitamin D3 bolus (80,000 IU), provide important insight into the response to vitamin D under in vivo conditions. In this study, we inspected 452 in vivo vitamin D target genes from peripheral blood mononuclear cells (PBMCs) detected in VitDHiD and found 61 of them involved in eight major KEGG (Kyoto Encyclopedia of Genes and Genomes) pathways of innate immunity. Under in vivo conditions in healthy individuals vitamin D either silences five pathways of innate immunity, stabilizes two and increases one, so that acute inflammation is suppressed and the release of cytokines is kept under control. A ranking of the 61 target genes by inducibility, basal expression and multiple involvements in the pathways highlighted the genes NFKBIA (NFκB inhibitor alpha), NFKBIZ, FOSL2 (FOS like 2, AP1 transcription factor subunit), JDP2 (Jun dimerization protein 2), PIK3R1 (phosphoinositide-3-kinase regulatory subunit 1), CLEC7A (C-type lectin domain containing 7A), DUSP6 (dual specificity phosphatase 6), NCF2 (neutrophil cytosolic factor 2), PLCB1 (phospholipase C beta 1), PLCG2 and TNFAIP3 (TNF alpha induced protein 3). In conclusion, vitamin D's in vivo effect on innate immunity in healthy adults is mediated by the interconnection of the pathways of neutrophil extracellular trap formation, Toll-like receptor, chemokine and phagosome signaling, NOD-like receptor, C-type lectin receptor, apoptosis and interleukin 17 through a limited set of proteins encoded by key target genes.

Humans

Strain-specific alterations in gut microbiome and host immune responses elicited by tolerogenic Bifidobacterium pseudolongum.

The beneficial effects attributed to Bifidobacterium are largely attributed to their immunomodulatory capabilities, which are likely to be species- and even strain-specific. However, their strain-specificity in direct and indirect immune modulation remain largely uncharacterized. We have shown that B. pseudolongum UMB-MBP-01, a murine isolate strain, is capable of suppressing inflammation and reducing fibrosis in vivo. To ascertain the mechanism driving this activity and to determine if it is specific to UMB-MBP-01, we compared it to a porcine tropic strain B. pseudolongum ATCC25526 using a combination of cell culture and in vivo experimentation and comparative genomics approaches. Despite many shared features, we demonstrate that these two strains possess distinct genetic repertoires in carbohydrate assimilation, differential activation signatures and cytokine responses signatures in innate immune cells, and differential effects on lymph node morphology with unique local and systemic leukocyte distribution. Importantly, the administration of each B. pseudolongum strain resulted in major divergence in the structure, composition, and function of gut microbiota. This was accompanied by markedly different changes in intestinal transcriptional activities, suggesting strain-specific modulation of the endogenous gut microbiota as a key to immune modulatory host responses. Our study demonstrated a single probiotic strain can influence local, regional, and systemic immunity through both innate and adaptive pathways in a strain-specific manner. It highlights the importance to investigate both the endogenous gut microbiome and the intestinal responses in response to probiotic supplementation, which underpins the mechanisms through which the probiotic strains drive the strain-specific effect to impact health outcomes.

Mice

Macrophage regulation of extracellular matrix remodeling in aging skeletal muscle.

The extracellular matrix (ECM) is a dynamic structural network that supports tissue architecture and regulates cell function. It is primarily composed of collagens, elastin, proteoglycans, and glycoproteins, which are synthesized by canonical and non-canonical ECM-producing cells. During aging, the ECM undergoes progressive changes in structure and composition, a process recently recognized as the 13th hallmark of aging. In skeletal muscle (SKM), age-associated ECM remodeling, largely regulated by immune system-ECM crosstalk, contributes to sarcopenia and impaired regeneration. Macrophages (MΦs), as key innate immune cells, regulate ECM dynamics both indirectly by activating canonical ECM-producing cells and directly by synthesizing ECM components. Notably, a distinct subset of ECM-producing MΦs that express collagen (COL+ MΦs) has been identified across multiple tissues, although their function in SKM homeostasis and aging remains poorly understood. Here, we review current knowledge of ECM production and remodeling, with special emphasis on MΦ involvement, including COL+ MΦs, as critical regulators of fibrogenesis, especially during SKM aging and regeneration.

Extracellular Matrix

Transcriptomic and proteomic signatures following AS03-adjuvanted Influenza A/H7N9 vaccine.

INTRODUCTION: Vaccines targeting avian influenza virus A/H7N9 are poorly immunogenic. While the immune responses can be improved with oil-in-water emulsion adjuvants such as Adjuvant System 03 (AS03), the cellular mechanisms underpinning the adjuvant effect are incompletely characterized and poorly understood. METHODS: We enrolled 30 healthy adult participants and used RNA sequencing and quantitative proteomics to characterize the response to two doses of the influenza A/H7N9 vaccine, with and without AS03, in six immune cell types. These responses were compared to those seen after administration of an unadjuvanted seasonal in uenza A/H3N2 variant vaccine to identify signatures unique to adjuvanted influenza vaccines and correlated with later antibody responses. Transcriptomic and proteomic analyses revealed that. RESULTS: AS03-adjuvanted vaccine was associated with upregulation of immune pathways in innate immune cells within 24h following vaccination for phagocytosis, antigen presentation and processing, inflammasome activation, NK-cell mediated cytotoxicity, IgA production, and interferon-response pathways. Moreover, while major histocompatibility complex (MHC I and II) upregulation was observed across multiple immune cell types, MHCII gene transcription was also increased in the neutrophil compartment, generating the hypothesis that neutrophils may play a more important role in antigen presentation than previously understood. DISCUSSION: Taken together, these data provide a more complete mechanistic understanding of oil-in-water adjuvants and their role in enhancing the immune response for pandemic influenza preparedness. CLINICAL TRIAL REGISTRATION: https://clinicaltrials.gov/study/NCT02921997?term=NCT02921997&viewType, idientifier NCT02921997.

Adult

Myeloid landscape of BRAF-mutant papillary thyroid cancer and thyroiditis.

Papillary thyroid cancer (PTC) is less aggressive when associated with lymphocytic thyroiditis (LT), even in the presence of oncogenic BRAF, including smaller tumours, less lymph node involvement and reduced extrathyroidal extension. To investigate possible immune mechanisms underlying this association, we compared the tumour microenvironment of PTC-BRAF with LT and that without LT using single-cell RNA sequencing (scRNA-seq). Single-cell libraries were generated from fresh and fixed tumour samples with post-dissociation viability >70% using the 10x Genomics Chromium Platform and sequenced on an Illumina NovaSeq 6000. We analysed scRNA-seq data from 11 PTC-BRAF tumours: four with LT (one publicly available sample) and seven without LT. Downstream analyses included quality control, batch correction, dimensionality reduction, and differential gene expression analysis. We found that neutrophils were the predominant myeloid cell type in PTCs without LT. Thyrocytes without LT showed significant expression of the neutrophil recruitment chemokine ECRG4. In the absence of LT, neutrophils expressed oncogenic genes with poor clinical outcomes. In contrast, thyrocytes from tumours with LT showed increased expression of MHC-II antigen presentation, consistent with effective immune surveillance. Thyrocytes and macrophages in the presence of LT showed enrichment of interferon gamma response pathways. Our data suggest that LT in thyroid cancer is associated with enhanced antigen presentation and fewer features of pro-tumourigenic innate immune activity. These results identify previously under-recognised innate immune cell population and associated transcriptomic features, which suggest new mechanisms to target immune treatments in PTC refractory to other therapies.

Humans

Identification of a necroptosis-related lncRNA prognostic signature and the hub RBP HNRNPK in esophageal squamous cell carcinoma.

ObjectiveEsophageal squamous cell carcinoma (ESCC) is a malignant tumor with poor prognosis. Necroptosis is important for tumor immunity, but its role in ESCC remains unclear. This retrospective bioinformatics study aimed to investigate the prognostic value of necroptosis-related long non-coding RNAs (lncRNAs) and to identify key lncRNA-binding proteins (RBPs) in ESCC patients.MethodsRNA transcriptome and clinical data of ESCC patients were obtained from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases. Necroptosis-related lncRNAs were identified through correlation analysis with necroptosis-related genes, subjected to consensus cluster analysis, and used to construct a prognostic risk model via least absolute shrinkage and selection operator (LASSO) regression. The hub RBP was experimentally validated by quantitative polymerase chain reaction (qPCR) using 30 pairs of ESCC and adjacent normal tissues from patients who underwent surgical resection.ResultsA total of 30 necroptosis-related lncRNAs were significantly correlated with overall survival (OS). The upregulated lncRNAs in the risk model were associated with high immune scores, innate immune cell infiltration, cluster 2 classification, and advanced T-stage disease (p&#x2009;<&#x2009;0.05). Three hub RBPs (HNRNPA1, HNRNPC, and HNRNPK) were identified through protein-protein interaction network analysis. qPCR confirmed that HNRNPK was significantly overexpressed in ESCC tissues compared to adjacent normal tissues (p&#x2009;<&#x2009;0.05).ConclusionsThe necroptosis-related lncRNA risk model is an independent prognostic factor for ESCC patients. HNRNPK was identified as a hub RBP significantly overexpressed in ESCC tissues. We hypothesize that HNRNPK may promote tumor progression through regulating proto-oncogene expression or modulating the immune microenvironment, though this requires further mechanistic validation.

Humans

Setdb2 Regulates Inflammatory Trigger-Induced Trained Immunity of Macrophages Through Two Different Epigenetic Mechanisms.

"Trained immunity" of innate immune cells occurs through a sequential two-step process where an initial pathogenic or sterile inflammatory trigger is followed by an amplified response to a later un-related secondary pathogen challenge. The memory effect is mediated at least in part through epigenetic modifications of the chromatin landscape. Here, we investigated the role of the epigenetic modifier Setdb2 in microbial (&#x3b2;-glucan) or sterile trigger (Western-diet-WD/oxidized-LDL-oxLDL)-induced trained immunity of macrophages. Using genetic mouse models and genomic analysis, we uncovered a critical role of Setdb2 in regulating proinflammatory and metabolic pathway reprogramming. We further show that Setdb2 regulates trained immunity through two different complementary mechanisms: one where it positively regulates glycolytic and inflammatory pathway genes via enhancer-promoter looping, and is independent of its enzymatic activity; while the second mechanism is associated with both increased promoter associated H3K9 methylation and repression of interferon response pathway genes. Interestingly, while both mechanisms occur in response to pathogenic training, only the chromatin-looping mechanism operates in response to the sterile inflammatory stimulus. These results reveal a previously unknown bifurcation in the downstream pathways that distinguishes between pathogenic and sterile inflammatory signaling responses associated with the innate immune memory response and may provide potential therapeutic opportunities to target cytokine vs. interferon pathways to limit complications of chronic inflammation.

Setdb2