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Patrolling monocytes control tumor metastasis to the lung.

The immune system plays an important role in regulating tumor growth and metastasis. Classical monocytes promote tumorigenesis and cancer metastasis, but how nonclassical "patrolling" monocytes (PMo) interact with tumors is unknown. Here we show that PMo are enriched in the microvasculature of the lung and reduce tumor metastasis to lung in multiple mouse metastatic tumor models. Nr4a1-deficient mice, which specifically lack PMo, showed increased lung metastasis in vivo. Transfer of Nr4a1-proficient PMo into Nr4a1-deficient mice prevented tumor invasion in the lung. PMo established early interactions with metastasizing tumor cells, scavenged tumor material from the lung vasculature, and promoted natural killer cell recruitment and activation. Thus, PMo contribute to cancer immunosurveillance and may be targets for cancer immunotherapy.

Animals

Exploring the proteomic landscape of THP-1 monocytes through two-challenge LPS induction.

Proteome remodelling is central to the regulation of innate immune activation, yet the temporal organisation of protein networks engaged during repeated lipopolysaccharide (LPS) stimulation remains incompletely defined. In the present study, label-free quantitative mass spectrometry-based proteomics was used to characterise protein abundance changes in THP-1 monocytes at early (30 min) and later (2 h) time points following a second LPS challenge. This analysis was complemented by an independent co-immunoprecipitation proteomics experiment designed to identify candidate proteins associated with the regulatory pseudo-kinase IRAK3 during early TLR4 signalling. At 30 min, differentially abundant proteins were enriched in pathways associated with pattern-recognition receptor signalling, NF-κB activity, RNA processing, phosphorylation, and ribonucleoprotein complex organisation. By 2 h, the proteomic response broadened to include oxidative phosphorylation, antigen processing and presentation, vesicle-mediated transport, protein folding, and cytokine-regulatory pathways. These findings indicate that repeated LPS stimulation is accompanied by progressive remodelling of inflammatory, metabolic, translational, and proteostatic programmes rather than major changes in protein identity. Co-immunoprecipitation identified established TLR/IRAK3-associated components together with candidate IRAK3-associated proteins linked to RNA regulation, kinase signalling, ubiquitin-mediated processes, redox control, cytoskeletal remodelling, and damage-associated molecular pattern responses. Collectively, these findings define a temporal framework of proteomic adaptation during repeated inflammatory stimulation and expand the range of candidate proteins potentially contributing to IRAK3-centred regulation of innate immune signalling.

Humans

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

Translation of scRNA-seq to a clinical blood test for infection diagnostics.

INTRODUCTION: Early and accurate triage of patients with febrile illness is crucial for appropriate treatment. While standard inflammatory biomarkers are often nonspecific, transcriptome analysis of peripheral blood has diagnostic potential. However, bulk gene expression data is often confounded by changes in cell count proportions, a more robust quantification of gene expression in specific single-cell types, such as monocytes, is required to serve as a reliable clinical biomarker. AREAS COVERED: Various methods to obtain single-cell-type gene expression results, including the gold standard of gene expression analysis after cell sorting and single-cell RNA sequencing, which are difficult to implement in the routine settings are discussed. Other method to interrogate gene expression of a single cell-type is needed. Finally, monocyte cell-type specific ratio-based biomarker (RBB, called Direct Leukocyte Single cell-type Transcript Abundance, or DIRECT LS-TA) which can estimate single cell-type (monocyte) specific gene expression without cell sorting is introduced. EXPERT OPINION: Traditional diagnostic test for differentiating infection has several limitations requiring breakthrough including turn-around time and cost. DIRECT LS-TA provides a reliable way to quantify monocyte-specific gene expression that strongly correlates with gold-standard methods. It is more affordable than single-cell RNA sequencing and can be readily implemented in clinical laboratories using widely available quantitative PCR or digital PCR machines.

Humans

Multiparametric flow cytometry immune profiling of pulmonary and extra-pulmonary tuberculosis reveals distinct blood-based biomarker signatures.

This study investigated immune cell distributions, cell-specific immune markers, and selected biomarker targets in pulmonary tuberculosis (PTB) and extrapulmonary tuberculosis (EPTB) using multiparametric flow cytometry (MFC). Whole blood was collected from 45 individuals, including healthy controls (HC), EPTB, and PTB patients (n&#x202f;=&#x202f;15/group). Peripheral blood leukocytes were analysed by MFC to characterize CD4+ and CD8+ T cells, natural killer (NK), invariant NKT (iNKT) and NKT cells, classical (CM), intermediate (IM) and non-classical monocytes (NCM), and activated monocytes (AM). Expression of GBP1, CALCOCO2, IFIT3, SNX10, ARG1, PD-1, and PD-L1 was assessed across these immune subsets. Increased frequencies of NK, NKT, and monocytes were observed in PTB and EPTB compared with HC, while CD4+, CD8+, iNKT, and AM were reduced. Monocyte-to-lymphocyte ratios were incrementally elevated in EPTB and PTB compared with HC. Despite variability of expression within groups, median biomarker fold-change expression changes were found between HC, EPTB and PTB groups; (i) (>2.0FC) for ARG1 in CD4, CD8, CM and AM, for CALCOCO2 in AM, GBP1 in CD8 and NCM, PD-1 in CD4, CD8, NK, IM and AM, PD-L1 in CD4, CD8, iNKT and NKT, NK, IM and AM and SNX10 in CD4, CD8, NCM, IM and AM (ii) (<2.0FC) in TB vs HC for CALCOCO2 in iNKT and NKT, IFIT3 in NCM, PD-1 in NK and NCM, PD-L1 in NCM, IM and AM and SNX10 in AM. Statistical significance was achieved for ARG1 (P&#x202f;=&#x202f;0.017) in CD4 cells. Our findings highlight distinct immune cell and biomarker signatures in PTB and EPTB.

Humans

CRISPRi screens identify the lncRNA, LOUP, as a multifunctional locus regulating macrophage differentiation and inflammatory signaling.

Long noncoding RNAs (lncRNAs) account for the largest portion of RNA from the transcriptome, yet most of their functions remain unknown. Here, we performed two independent high-throughput CRISPRi screens to understand the role of lncRNAs in monocyte function and differentiation. The first was a reporter-based screen to identify lncRNAs that regulate TLR4-NFkB signaling in human monocytes and the second screen identified lncRNAs involved in monocyte to macrophage differentiation. We successfully identified numerous noncoding and protein-coding genes that can positively or negatively regulate inflammation and differentiation. To understand the functional roles of lncRNAs in both processes, we chose to further study the lncRNA LOUP [lncRNA originating from upstream regulatory element of SPI1 (also known as PU.1)], as it emerged as a top hit in both screens. Not only does LOUP regulate its neighboring gene, the myeloid fate-determining factor SPI1, thereby affecting monocyte to macrophage differentiation, but knockdown of LOUP leads to a broad upregulation of NFkB-targeted genes at baseline and upon TLR4-NFkB activation. LOUP also harbors three small open reading frames capable of being translated and are responsible for LOUP's ability to negatively regulate TLR4/NFkB signaling. This work emphasizes the value of high-throughput screening to rapidly identify functional lncRNAs in the innate immune system.

RNA, Long Noncoding

Rare damaging CCR2 variants are associated with lower lifetime cardiovascular risk.

BACKGROUND: Previous work has shown a role of CCL2, a key chemokine governing monocyte trafficking, in atherosclerosis. However, it remains unknown whether targeting CCR2, the cognate receptor of CCL2, provides protection against human atherosclerotic cardiovascular disease. METHODS: Computationally predicted damaging or loss-of-function (REVEL&#x2009;>&#x2009;0.5) variants within CCR2 were detected in whole-exome-sequencing data from 454,775 UK Biobank participants and tested for association with cardiovascular endpoints in gene-burden tests. Given the key role of CCR2 in monocyte mobilization, variants associated with lower monocyte count were prioritized for experimental validation. The response to CCL2 of human cells transfected with these variants was tested in migration and cAMP assays. Validated damaging variants were tested for association with cardiovascular endpoints, atherosclerosis burden, and vascular risk factors. Significant associations were replicated in six independent datasets (n&#x2009;=&#x2009;1,062,595). RESULTS: Carriers of 45 predicted damaging or loss-of-function CCR2 variants (n&#x2009;=&#x2009;787 individuals) were at lower risk of myocardial infarction and coronary artery disease. One of these variants (M249K, n&#x2009;=&#x2009;585, 0.15% of European ancestry individuals) was associated with lower monocyte count and with both decreased downstream signaling and chemoattraction in response to CCL2. While M249K showed no association with conventional vascular risk factors, it was consistently associated with a lower risk of myocardial infarction (odds ratio [OR]: 0.66, 95% confidence interval [CI]: 0.54-0.81, p&#x2009;=&#x2009;6.1&#x2009;&#xd7;&#x2009;10-5) and coronary artery disease (OR: 0.74, 95%CI: 0.63-0.87, p&#x2009;=&#x2009;2.9&#x2009;&#xd7;&#x2009;10-4) in the UK Biobank and in six replication cohorts. In a phenome-wide association study, there was no evidence of a higher risk of infections among M249K carriers. CONCLUSIONS: Carriers of an experimentally confirmed damaging CCR2 variant are at a lower lifetime risk of myocardial infarction and coronary artery disease without carrying a higher risk of infections. Our findings provide genetic support for the translational potential of CCR2-targeting as an atheroprotective approach.

Humans

Hepatocyte-Specific Deficiency of Endoplasmic Reticulum-Associated Degradation Induces Coordinated Innate-Adaptive Immune Responses.

Hepatic inflammation is a defining feature of Metabolic Dysfunction-Associated Steatohepatitis (MASH), yet the specific contributions of individual immune cell populations and their reciprocal interactions remain incompletely understood. In this study, we combined flow cytometry with single-cell transcriptomic profiling to characterize the hepatic immune landscape in a novel model of spontaneous MASH caused by hepatocyte-specific deficiency of endoplasmic reticulum-associated degradation (ERAD). Hepatic ERAD deficiency led to the expansion of multiple immune cell populations in the liver, including CD8+ T cells, macrophages, monocytes, and dendritic cells, accompanied by extensive functional reprogramming of both innate and adaptive immune compartments. Myeloid cells exhibited enhanced phagocytic activity and increased antigen processing and presentation, whereas CD8+ T cells displayed elevated proliferation capacity, DNA repair activity and cytotoxicity. Notably, two functionally distinct triggering receptor expressed on myeloid cells 2 (TREM2)-expressing macrophage subsets emerged during the progression of ERAD deficiency-induced MASH. Depletion of CD8+ T cells increased monocyte infiltration and aggravated liver injury, suggesting that CD8+ T cells exert a previously unrecognized protective role by restraining monocyte recruitment. Collectively, these findings reveal highly coordinated interactions between innate and adaptive cells during MASH progression and identify CD8+ T cells as potential regulators of monocyte infiltration and hepatic injury.

Animals

Complement Activation Linked to Type II Interferon Signaling in Still Disease.

OBJECTIVE: Still disease (SD) is an autoinflammatory syndrome characterized by innate immune dysregulation. Although complement can drive inflammation, its involvement in SD remains to be defined. Thus, we aimed to assess complement activation in SD. METHODS: Complement was assessed using transcriptomic, proteomic, and in vitro approaches. RNA sequencing of monocytes was performed in healthy donors (n&#xa0;=&#xa0;15), those with nonsystemic juvenile idiopathic arthritis (JIA; n&#xa0;=&#xa0;8), patients with SD at onset (n&#xa0;=&#xa0;19) and remission (n&#xa0;=&#xa0;18), and those with macrophage activation syndrome (n&#xa0;=&#xa0;2). Whole-blood NanoString analysis of complement and interferon (IFN)-related gene expression was conducted in patients with SD (active n&#xa0;=&#xa0;41, inactive n&#xa0;=&#xa0;33) and JIA (n > 600). Complement products and inflammatory mediators were measured by Luminex and enzyme-linked immunosorbent assay. Functional complement activity was evaluated in SD (active n&#xa0;=&#xa0;30, inactive n&#xa0;=&#xa0;67) and JIA sera (n&#xa0;=&#xa0;12). In vitro assays examined monocytic C1q induction and complement-mediated CD8+ T cell activation. RESULTS: Transcriptomic analysis of monocytes from patients with SD at onset revealed enrichment of the complement cascade compared with patients in remission (adjusted P&#xa0;=&#xa0;3.7&#x2009;&#xd7;&#x2009;10-36), ranking among the top 10 up-regulated pathways. Classical complement genes (C1QB/C1QC) were markedly up-regulated in onset SD compared with patients with remission SD and JIA. Patients with active SD showed increased C1q, C3a, C5a, and terminal complement complex protein levels, with enhanced functional classical complement activity. Whole-blood C1QB/C1QC expression correlated with IFN-related markers, including interleukin-18, CXCL9, and CXCL10. Recombinant IFN-&#x3b3; induced monocytic C1q, whereas C1q enhanced IFN-&#x3b3; production by CD8+ T cells, supporting a feed-forward loop. CONCLUSION: SD is characterized by complement activation with marked up-regulation of C1q, which is closely linked to IFN-&#x3b3;/type II signaling.

Journal Article

The phosphate exporter XPR1 promotes gasdermin D-independent mature IL-1&#x3b2; secretion.

Interleukin (IL)-1&#x3b2; is a leaderless inflammatory cytokine that is not secreted via the classical endoplasmic reticulum-Golgi pathway. Instead, m(ature) IL-1&#x3b2; secretion is classically associated with pyroptosis, a caspase-dependent inflammatory cell death mediated by gasdermin D (GSDMD) pore formation at the plasma membrane. However, human monocytes can secrete mIL-1&#x3b2; in the absence of cell death, and the contribution of GSDMD in this secretory pathway remains poorly defined. Here, we distinguished two pathways for mIL-1&#x3b2; secretion in living human monocytic cells : a rapid, GSDMD-dependent pathway and a slower, GSDMD-independent pathway. Using a genome-wide CRISPR-Cas9 screen, we identified XPR1 (Xenotropic and Polytropic retrovirus Receptor 1) as a regulator of the GSDMD-independent pathway. XPR1, the only phosphate exporter identified in metazoans, has not previously been implicated in cytokine secretion. Genetic invalidation of XPR1 in GSDMD-deficient monocytic cells markedly reduced IL-1&#x3b2; secretion. We further showed that this regulatory function requires XPR1 surface expression and phosphate export activity. These findings reveal an unexpected link between phosphate homeostasis and non-lytic mIL-1&#x3b2; secretion, opening new opportunities to modulate IL-1&#x3b2;-driven inflammatory diseases.

IL-1&#x3b2; secretion

Genome-wide H3K4me3 profiling of circulating immune cells reveals dynamic epigenetic reprogramming during acute critical COVID-19.

INTRODUCTION: Severe COVID-19 is associated with innate immune dysregulation resembling sepsis-induced immunoparalysis. Epigenetic mechanisms, particularly changes in H3K4me3 enrichment at gene promoters, have been observed in immune tolerance and monocyte dysfunction in sepsis. Whether comparable H3K4me3 alterations occur during acute critical COVID-19 illness has not been investigated. METHODS: In this prospective single-center study, 46 hospitalized COVID-19 patients were enrolled, of whom 27 were treated in the intensive care unit (ICU group) and 19 on the normal ward (non-ICU group). Genome-wide H3K4me3 ChIP-seq was performed on PBMCs at hospital admission (T1) in the total cohort and after seven days (T2) in the ICU group. Monocyte HLA-DR expression and ex vivo TLR-stimulated cytokine secretion were assessed as functional immune readouts. RESULTS: Among 706 differentially bound consensus peaks with promoter association between ICU and non-ICU groups, 704 showed increased H3K4me3 occupancy in ICU patients, predominantly at neutrophil effector gene loci, supported by pathway enrichment of neutrophil degranulation and innate immune activation. Monocyte HLA-DR expression and ex vivo TLR-stimulated IL-6 secretion were persistently reduced throughout the first week of ICU treatment. Longitudinal profiling in the ICU group revealed a shift from an interferon-driven chromatin signature at admission toward sustained innate immune activation and ECM remodeling at day seven. CONCLUSION: This study provides the first genome-wide H3K4me3 characterization of circulating immune cells during acute critical COVID-19, demonstrating that epigenetic reprogramming is an active and dynamic process that mirrors the functional immune dysregulation observed in these patients.

Humans

BACH1 orchestrates macrophage state transitions to coordinate regenerative inflammation.

Efficient tissue regeneration requires the precise coordination of inflammatory and regenerative programs, principally mediated by monocyte-derived macrophages. However, the transcriptional wiring and epigenomic processes behind complex macrophage subtype specification and transition between the different states are not known. Here we have identified the transcriptional repressor BACH1 as a critical, cell-intrinsic regulator of monocyte-derived macrophage specification during skeletal muscle regeneration. Using a myeloid-specific BACH1 knockout mouse model, we demonstrate that BACH1 deficiency disrupts the temporal coordination of monocyte-to-macrophage differentiation, leading to aberrant macrophage subsets with concurrent opposing pro- and anti-inflammatory features. Single-cell RNA-sequencing profiling reveals that BACH1 controls a core transcriptional network, including Nfkb1, Cebpb, and interferon signaling, governing inflammatory resolution and functional macrophage specialization. Mechanistically, BACH1 loss accelerates macrophage differentiation but also affects its core cellular identity, resulting in sustained, rather than declining inflammatory programs including upregulation of Il1b and thus, defective tissue remodeling. These immune alterations compromise the paracrine landscape during regenerative inflammation and impair muscle stem cell differentiation. Our findings establish BACH1 as a molecular tuner or controller that integrates early innate immune signaling with regenerative output, positioning it as a central node linking transcriptional control, immune fate decisions, and tissue repair.

Animals

Uncovering metabolite-immune interactions in the pathogenesis of psoriatic arthritis: A 2-sample Mendelian randomization study.

PsA is a chronic inflammatory joint condition associated with psoriasis, and its underlying mechanisms are not fully elucidated. Serum metabolites, as direct reflections of metabolic status, may influence disease progression by regulating immune cell function; however, the causal relationships and specific pathways require further investigation. The present investigation utilized a 2-sample bidirectional MR methodology, leveraging extensive pooled GWAS data to thoroughly evaluate the causal relationships between 1440 serum metabolites and PsA. Additionally, mediation MR analysis was performed to explore the possible mediating effects of 731 immune cell characteristics. In the primary analysis, inverse-variance weighted was employed, and this was further supported by various sensitivity analyses to confirm the reliability of the findings. The genetic method to infer causality analysis revealed significant positive causal associations between 10 serum metabolites and PsA risk, with quinolinate levels demonstrating the most significant correlation (OR&#x2005;=&#x2005;1.56, 95% CI: 1.26-1.93); while 4 metabolites (e.g., citrate levels, OR&#x2005;=&#x2005;0.74, 95% CI: 0.61-0.89) exhibited protective effects. Regarding immune cells, 6 cellular features (e.g., CD20 on B cells) were positively correlated with disease risk, whereas 5 features (primarily HLA-DR expression on monocyte subsets) showed negative correlations. Mediation analysis identified 3 significant pathways,the percentage of the effect explained by the mediator: N6,N6,N6-trimethyllysine levels mediated via B cells (CD20 on IgD+ CD38br), with a proportion of 33.2%; 1-stearoyl-2-docosahexaenoyl-GPE (18:0/22:6) levels mediated through monocytes (HLA-DR on CD14- CD16-) with a 32.0% proportion; the unknown metabolite X-24736 also mediated 42.1% of the protective effect via the same monocyte phenotype. This study revealed that elevated amino acid-related metabolites and glycerophospholipids significantly increase PsA risk through immune cell effects. These are closely associated with PsA pathogenesis and may serve as potential biomarkers. The novel findings underscore metabolic-immune interactions as targets for biomarkers and therapies in PsA, advancing personalized medicine.

Humans

Integrated Cytokine and Immune Cell Profiling Reveals a Distinct Immune Signature Associated with High-Altitude Pulmonary Edema.

High-altitude pulmonary edema (HAPE) is a rapidly progressive, life-threatening disorder arising in otherwise healthy individuals upon ascent to high altitude, yet the mechanisms underlying maladaptive vascular leak remain poorly defined. Although elevated pulmonary arterial pressure and capillary stress failure are recognized as central hemodynamic drivers, accumulating evidence indicates that innate immune dysregulation is an equally critical, largely unexplored determinant of HAPE. To systematically delineate the immune and molecular programs that distinguish pathological responses to hypobaric hypoxia from acclimatization, peripheral blood along with clinical details was collected from low-altitude controls (LA-Cntrl, number of participants, (n = 19), healthy high-altitude sojourners (HA-Cntrl, n = 47), and HAPE patients (n = 90). Plasma proteomic markers were quantified using a targeted panel, while monocyte and dendritic cell subsets in peripheral blood mononuclear cells were immunophenotyped by multicolor flow cytometry. HA-Cntrl subjects displayed an anti-inflammatory profile, marked by the suppression of CXC chemokine receptor 3 axis chemokines. HAPE patients, in contrast, exhibited a pro-inflammatory, vascular injury signature, with elevated levels of inflammatory interleukins and myeloid and chemotactic factors. This inflammatory signature was accompanied by the expansion of classical monocytes, implicating a myeloid vascular program associated with HAPE.

Humans

High expression of Rex-orf-I and HBZ mRNAs and bronchiectasis in lung of HTLV-1A/C infected macaques.

HTLV-1 type-A rarely causes lung disease in humans, whereas HTLV-1 type-C is more frequently associated with respiratory failure and premature death. We investigated the genetic basis of HTLV-1C morbidity by constructing a chimeric HTLV-1A/CoI-L encompassing the highly divergent type C orf-I. We demonstrate that systemic infectivity of HTLV-1A and HTLV-1A/CoI-L is equivalent in macaques, but viral expression in lungs is significantly higher in HTLV-1A/CoI-L infection. In addition, bronchoalveolar-lavage immune cell dynamics differs greatly with neutrophils and monocytes producing TNF-&#x3b1; in HTLV-1A/CoI-L, but producing IL-10 in HTLV-1A infection. Animals infected with HTLV-1A/CoI-L develops bronchiectasis at 10 months from infection, but at the same timepoint those infected with HTLV-1A do not. HTLV-1A/CoI-L expressed a 16&#x2009;kDa fusion protein (p16C) via a doubly spliced, Rex-orf-IC, mRNA able to shield T-cells from efferocytosis, a monocyte function that mitigates inflammation via clearance of apoptotic cells. The Rex-orf-IC mRNA is expressed as more frequent in the lung of HTLV-1A/CoI-L than HTLV-1A infected animals. Since defective efferocytosis is associated with lung obstructive pathologies, the data raise the hypothesis that p16C may contribute to the lung morbidity observed in HTLV-1C infection.

Animals

Prior vaccination prevents overactivation of innate immune responses during COVID-19 breakthrough infection.

At this stage in the COVID-19 pandemic, most infections are "breakthrough" infections that occur in individuals with prior severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) exposure. To refine long-term vaccine strategies against emerging variants, we examined both innate and adaptive immunity in breakthrough infections. We performed single-cell transcriptomic, proteomic, and functional profiling of primary and breakthrough infections to compare immune responses from unvaccinated and vaccinated individuals during the SARS-CoV-2 Delta wave. Breakthrough infections were characterized by a less activated transcriptomic profile in monocytes and natural killer cells, with induction of pathways limiting monocyte migratory potential and natural killer cell proliferation. Furthermore, we observed a female-specific increase in transcriptomic and proteomic activation of multiple innate immune cell subsets during breakthrough infections. These insights suggest that prior SARS-CoV-2 vaccination prevents overactivation of innate immune responses during breakthrough infections with discernible sex-specific patterns and underscore the potential of harnessing vaccines in mitigating pathologic immune responses resulting from overactivation.

Immunity, Innate

Single-cell expression quantitative trait locus Mendelian randomization reveals immune cell-specific causal regulatory networks and actionable targets in polycystic ovary syndrome.

ObjectiveTo systematically investigate whether the pathogenesis of polycystic ovary syndrome (PCOS) is causally related to dysregulated gene expression in specific immune cell subsets, and to evaluate the potential of these causal genes as actionable drug targets.MethodsThis study employed a two-sample Mendelian randomization (MR) framework using publicly available genome-wide association study (GWAS) summary statistics. The participant data included 797 PCOS cases and 140,558 controls (no direct patient recruitment was involved). Instrumental variables were derived from high-resolution immune cell-specific single-cell expression quantitative trait locus (sc-eQTL) data (OneK1K project) across 14 immune cell types. Primary analyses utilized the inverse-variance weighted (IVW) method. Shared causal variants were validated using Bayesian colocalization. Phenome-wide association analysis (PheWAS), external transcriptomic dataset validation (GSE8157), and DrugBank database screening were conducted for pleiotropy assessment and drug repositioning.ResultsMR analysis revealed genome-wide significant causal associations for GLIPR1 in non-classical monocytes (Mono NC) and XBP1 in CD4+ effector memory T cells (CD4 ET) with PCOS risk. Higher GLIPR1 expression was associated with a decreased PCOS risk (OR = 0.669, P = 4.34&#xd7;10-6), whereas higher XBP1 expression was associated with an increased risk (OR = 1.406, P = 9.53&#xd7;10-8). Colocalization analysis confirmed that GLIPR1 shares a causal variant with PCOS (PP.H4 = 96.73%). PheWAS and external validation confirmed the safety profile and significant upregulation (P = 0.03) of GLIPR1. Drug repositioning identified SOT-107, a Phase III protein therapy drug, as a potential interacting agent for GLIPR1.ConclusionsThis sc-eQTL MR study reveals immune cell-specific causal regulatory networks in PCOS. GLIPR1 in non-classical monocytes represents a high-confidence protective target, while XBP1 provides suggestive evidence for immune-mediated pathogenesis. The candidate drug SOT-107 highlights theoretical repositioning opportunities, though rigorous preclinical validation remains required.

Female