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At least 19 recordsLinked to original sources

Genome-Wide Aggregated Trans Effects Analysis Identifies Genes Encoding Immune Checkpoints as Core Genes for Rheumatoid Arthritis.

OBJECTIVE: The sparse effector "omnigenic" hypothesis postulates that the polygenic effects of common single nucleotide polymorphisms (SNPs) on a typical complex trait are mediated by trans effects that coalesce on expression of a relatively sparse set of core genes. The objective of this study was to identify core genes for rheumatoid arthritis by testing for association of rheumatoid arthritis with genome-wide aggregated trans effects (GATE) scores for expression of each gene as transcript in whole blood or as circulating protein levels. METHODS: GATE scores were calculated for 5,400 cases and 453,705 non-cases of primary rheumatoid arthritis in UK Biobank participants of European ancestry. RESULTS: Testing for association with GATE scores identified 16 putative core genes for rheumatoid arthritis outside the HLA region, of which six-TP53BP1, PDCD1, TNFRSF14, LAIR1, LILRA4, and IDO1-were supported by Mendelian randomization analysis based on the marginal likelihood of the causal effect parameter. Five of these 16 genes were validated by a reported association of rheumatoid arthritis with SNPs within 200 kb of the transcription site, eight by association of the measured protein level with rheumatoid arthritis in UK Biobank, 10 by experimental perturbation in mouse models of inflammatory arthritis, and two-CTLA4 and PDCD1-by evidence that drugs targeting the gene cause or ameliorate inflammatory arthritis in humans. Fourteen of these 16 genes are in pathways affecting immunity or inflammation, and six-CD5, CTLA4, TIGIT, LAIR1, TNFRSF14, and PDCD1-encode receptors that have been characterized as immune checkpoints exploited by cancer cells to escape the immune response. CONCLUSION: These results highlight the key role of immune checkpoints in rheumatoid arthritis and identify possible therapeutic targets.

Humans

Glucocorticoids mobilize macrophages by transcriptionally up-regulating the exopeptidase DPP4.

Glucocorticoids are potent endogenous anti-inflammatory molecules, and their cognate receptor, glucocorticoid receptor (GR), is expressed in nearly all immune cells. Macrophages are heterogeneous immune cells having a central role in both tissue homeostasis and inflammation and also play a role in the pathogenesis of some inflammatory diseases. Paradoxically, glucocorticoids have only a limited efficacy in controlling the resolution of these macrophage-related diseases. Here, we report that the transcriptomes of monocyte-like THP-1 cells and macrophage-like THP-1 cells (THP1-MΦ) have largely conserved gene expression patterns. In contrast, the differentiation to THP1-MΦ significantly altered the sensitivity of gene transcription to glucocorticoids. Among glucocorticoid-regulated genes, we identified the exopeptidase dipeptidyl peptidase-4 (DPP4) as a critical glucocorticoid-responsive gene in THP1-MΦ. We found that GR directly induces DPP4 gene expression by binding to two glucocorticoid-responsive elements (GREs) within the DPP4 promoter. Additionally, we show that glucocorticoid-induced DPP4 expression is blocked by the GR antagonist RU-486 and by GR siRNA transfection and that DPP4 enzyme activity is reduced by DPP4 inhibitors. Of note, glucocorticoids highly stimulated macrophage mobility; unexpectedly, DPP4 mediated the glucocorticoid-induced macrophage migration, and siRNA-mediated knockdowns of GR and DPP4 blocked dexamethasone-induced THP1-MΦ migration. Moreover, glucocorticoid-induced DPP4 activation was also observed in proinflammatory M1-polarized murine macrophages, as well as peritoneal macrophages, and was associated with increased macrophage migration. Our results indicate that glucocorticoids directly up-regulate DPP4 expression and thereby induce migration in macrophages, potentially explaining why glucocorticoid therapy is less effective in controlling macrophage-dominated inflammatory disorders.

Animals

Human genetic variation reveals FCRL3 is a lymphocyte receptor for Yersinia pestis.

Yersinia pestis is the bacterium responsible for plague, one of the deadliest diseases in history. To discover human genetic determinants of Y. pestis infection, we utilized nearly 1,000 genetically diverse lymphoblastoid cell lines in a cellular genome-wide association study. A nonsynonymous SNP, rs2282284 (N721S), in Fc receptor-like 3 (FCRL3) was associated with bacterial invasion of host cells (p = 9 × 10-8). Overexpressed FCRL3 facilitated attachment and invasion of Y. pestis and colocalized with Y. pestis at attachment sites. These properties were variably conserved across the FCRL family, revealing an immunoglobulin-like domain and signaling motifs shared by FCRL3 and FCRL5 to be necessary for attachment and invasion. Direct binding to FCRL5 extracellular domain was confirmed, and B cells (the primary cells that express FCRLs) were preferentially invaded by Y. pestis. Thus, Y. pestis hijacks FCRL proteins, possibly taking advantage of an immune receptor to create a lymphocyte niche during infection.

Yersinia pestis

Platelet triggering receptor expressed on myeloid cells-like transcript 1 regulation in healthy donors and patients at risk of bleeding and thrombosis.

BACKGROUND: Triggering receptor expressed on myeloid cells-like transcript 1 (TLT-1), a platelet-specific &#x3b1;-granule protein, is implicated in hemostasis, but its regulation remains unclear. Platelet dysfunction contributes to trauma-induced coagulopathy (TIC) and thrombotic complications in trauma or mechanical circulatory support (MCS); however, underlying mechanisms remain poorly understood. OBJECTIVES: This study investigated the molecular mechanisms underlying soluble TLT (sTLT)-1 release and its role as a biomarker of platelet dysfunction in patients with severe trauma or receiving MCS. METHODS: TLT-1 dynamics on platelets exposed to glycoprotein (GP)VI ligand, coagulation, or shear stress in vitro were evaluated by ELISA and immunoblotting. sTLT-1 was measured in plasma from trauma or MCS-treated patients and healthy donors. Associations with TIC, injury severity, and mortality were assessed. RESULTS: Proteolysis of TLT-1 to release a 10- to 17-kDa fragment was metalloproteinase dependent and blocked by ADAM10 and ADAM17 inhibition. Unlike GPVI, platelet TLT-1 exposure increased following PAR-1 activation. sTLT-1 was elevated in trauma patients compared with controls and correlated with TIC (P < .05) and injury severity (P < .01). Receiver-operating characteristic analysis demonstrated discriminatory performance for TIC (area under the curve, 0.78; P = .011), with a Youden cutoff of 1.180 ng/mL yielding 89% sensitivity and 73% specificity. Platelet TLT-1 was basally expressed, mobilized 2.5-fold with activation, and shed in response to GPVI ligation and plasma recalcification. Shear-exposed platelets and plasma from MCS-treated patients exhibited elevated sTLT-1 levels. CONCLUSION: Unlike GPVI, TLT-1 increased on activated platelets and was regulated by ADAM10 and ADAM17. TLT-1 release is triggered by shear stress, GPVI ligands or activated factor X. Plasma sTLT-1 was associated with trauma severity and TIC.

Humans

Dengue Virus Replicative-Form dsRNA Is Recognized by Both RIG-I and MDA5 to Activate Innate Immunity.

RIG-I like receptors (RLRs) are a family of cytosolic RNA sensors that sense RNA virus infection to activate innate immune response. It is generally believed that different RNA viruses are recognized by either RIG-I or MDA5, two important RLR members, depending on the nature of pathogen-associated molecular patterns (PAMPs) that are generated by RNA virus replication. Dengue virus (DENV) is an important RNA virus causing serious human diseases. Despite extensive investigations, the molecular basis of the DENV PAMP recognized by the host RLR has been poorly defined. Here, we demonstrated that the DENV infection-induced interferon response is dependent upon both RIG-I and MDA5, with RIG-I playing a predominant role. Next we purified the DENV PAMP RNA from the DENV-infected cells, and demonstrated that the purified DENV PAMP is viral full-length double-stranded RNA bearing 5'ppp modifications, likely representing the viral replicative-form RNA. Finally, we confirmed the nature of the DENV PAMP by reconstituting the viral replicative-form RNA from in vitro synthesized DENV genomic RNA. In conclusion, our work not only defined the molecular basis of the RLR-PAMP interaction during DENV infection, but also revealed the previously underappreciated recognition of a distinct moiety of the same PAMP by different RLRs in innate immunity against RNA viruses.

Interferon-Induced Helicase, IFIH1

High baseline PD-1+ CD8 T Cells and TIGIT+ CD8 T Cells in circulation associated with response to PD-1 blockade in patients with non-small cell lung cancer.

Blockade of PD-1 or its ligand PD-L1 with antibodies revolutionized treatment for stage III and IV non-small cell lung cancer (NSCLC) since FDA approval in 2015. However, resistance to PD-1/PD-L1 blockade remains a challenge, highlighting the need for biomarkers. This study analyzed 36 stage III and IV NSCLC patients, classified as responders or non-responders by iRECIST criteria. Peripheral blood mononuclear cells collected at baseline and post-treatment were examined for surface and intracellular markers via flow cytometry. CITE sequencing of CD8 T cells from three patients and plasma ctDNA analysis from 13 patients was performed using an ultrasensitive barcoding and next-generation sequencing method. Phenotypic analysis of CD8 T cells revealed higher TIGIT and PD-1 expression at baseline in responders compared to non-responders. Long-term responders (>&#x2009;21&#xa0;months) exhibited increased TCF-1+PD-1+ CD8 T cell frequencies relative to shorter-term responders (>&#x2009;15&#xa0;months) and non-responders. CITE sequencing revealed intrinsic differences in immune regulation pathways between responders and non-responders. Finally, non-responders showed elevated and increasing ctDNA levels post-treatment, correlating with declining TCF-1+PD-1+ CD8 T cells. Our data suggests combining CD8 T cell analysis with ctDNA dynamics could identify promising biomarkers for monitoring clinical response and treatment efficacy to PD-1/PD-L1 blockade in NSCLC.

Humans

The transcription factor GATA-3 controls cell fate and maintenance of type 2 innate lymphoid cells.

Innate lymphoid cells (ILCs) reside at mucosal surfaces and control immunity to intestinal infections. Type 2 innate lymphoid cells (ILC2s) produce cytokines such as IL-5 and IL-13, are required for immune defense against helminth infections, and are involved in the pathogenesis of airway hyperreactivity. Here, we have investigated the role of the transcription factor GATA-3 for ILC2 differentiation and maintenance. We showed that ILC2s and their lineage-specified bone marrow precursors (ILC2Ps), as identified here, were characterized by continuous high expression of GATA-3. Analysis of mice with temporary deletion of GATA-3 in all ILCs showed that GATA-3 was required for the differentiation and maintenance of ILC2s but not for ROR&#x3b3;t(+) ILCs. Thus, our data demonstrate that GATA-3 is essential for ILC2 fate decisions and reveal similarities between the transcriptional programs controlling ILC and T helper cell fates.

Animals

Elevated Triggering Receptor Expressed on Myeloid Cells 2 Expression in Tumor-Associated Macrophages Suppresses Cytotoxic T Cell Infiltration and Facilitates Immune Escape in Colorectal Cancer.

BACKGROUND & AIMS: Emerging evidence supports a crucial role for tumor-associated macrophages in shaping the immunosuppressive tumor microenvironment. Furthermore, research has identified that the triggering receptor expressed on myeloid cells 2 has immunomodulatory functions. The present investigated the potential effect of triggering receptor expressed on myeloid cells 2 expression in tumor-associated macrophages on facilitating immune evasion in colorectal cancer. METHODS: Immunohistochemical analysis of clinical specimens, complemented by extensive data mining from The Cancer Genome Atlas, revealed a significant upregulation of triggering receptor expressed on myeloid cells 2 in colorectal cancer-associated tumor-associated macrophages, with this upregulation exhibiting a correlation with poor patient prognosis. RESULTS: Mechanistically, triggering receptor expressed on myeloid cells 2+ tumor-associated macrophages were found to drive fibroblast activation through transforming growth factor-&#x3b2; signaling, inducing fibroblast-activated protein-positive cancer-associated fibroblasts that secrete collagen I/III to establish dense peritumoral barriers. Spatial profiling revealed that these fibrous structures physically impede CD8+ T-cell infiltration, restricting cytotoxic lymphocytes to stromal compartments. Intriguingly, triggering receptor expressed on myeloid cells 2 deficiency enhanced the secretion of matrix metalloproteinase 13 by macrophages, thereby promoting extracellular matrix degradation and improving T-cell penetration. In vivo, Trem2-knockout mice showed a reduction in tumor growth with enhanced intratumoral CD8+ T-cell infiltration compared with wild-type controls. CONCLUSIONS: Our findings establish triggering receptor expressed on myeloid cells 2+ tumor-associated macrophages as central regulators of stromal remodeling and suggest that therapeutic targeting of the triggering receptor expressed on myeloid cells 2/transforming growth factor-&#x3b2;/fibroblast-activated protein pathway may overcome immune resistance in patients with colorectal cancer.

Colorectal Neoplasms

A TIGIT nanotrapping-guided STING-activatable immunometabolic strategy overcomes innate immune silence and T cell exhaustion in breast cancer.

Breast cancer exhibits a profoundly immunosuppressive tumor microenvironment (TME), where innate immune silence prevents antigen sensing and persistent T cell exhaustion limits effector responses, rendering most immunotherapies ineffective. Clinical profiling of 1093 The Cancer Genome Atlas (TCGA) cases identified a glucose-fueled glutathione (GSH)-glutathione peroxidase 4 (GPX4)-dihydrolipoamide S-acetyltransferase (DLAT) axis as a dominant metabolic shield that suppresses oxidative stress, and thereby enforces both stimulator of interferon genes (STING) silence and CD8+ T cell exclusion. To dismantle this barrier, we developed an immunometabolic nanotherapy, GOx/ES-CO-LDH@TIGIT-Nanotrap (TNT). In acidic tumors, proton-driven layered double hydroxide (LDH) disassembly releases glucose oxidase (GOx) and extremely small cuprous oxide (ES-CO). GOx depletes glucose and nicotinamide adenine dinucleotide phosphate (NADPH) to induce disulfidptosis, while ES-CO releases cuprous ions (Cu+) that trigger cuproptosis via binding to lipoylated mitochondrial proteins. Their mutual biochemical amplification produces a cycloacclerated disulfidptosis-cuproptosis cascade that collapses the GSH-GPX4-DLAT axis and restores STING activation. Meanwhile, the macrophage-derived T cell immunoreceptor with Ig and ITIM domains (TIGIT) Nanotrap sequesters CD155 to prevent T cell suppression. Together, this coordinated innate reactivation and adaptive rescue converts immune-cold tumors into STING-inflamed and T cell responsive lesions.

Female

Biological correlates of elevated soluble TREM2 in cerebrospinal fluid.

Cerebrospinal fluid (CSF) soluble triggering receptor expressed on myeloid cells-2 (sTREM2) is an emerging biomarker of neuroinflammation in Alzheimer's disease (AD). Yet, sTREM2 expression has not been systematically evaluated in relation to concomitant drivers of neuroinflammation. While associations between sTREM2 and tau in CSF are established, we sought to determine additional biological correlates of CSF sTREM2 during the prodromal stages of AD by evaluating CSF A&#x3b2; species (A&#x3b2;x-40), a fluid biomarker of blood-brain barrier integrity (CSF/plasma albumin ratio), and CSF biomarkers of neurodegeneration measured in 155 participants from the Vanderbilt Memory and Aging Project. A novel association between high CSF levels of both sTREM2 and A&#x3b2;x-40 was observed and replicated in an independent dataset. A&#x3b2;x-40 levels, as well as the CSF/plasma albumin ratio, explained additional and unique variance in sTREM2 levels above and beyond that of CSF biomarkers of neurodegeneration. The component of sTREM2 levels correlated with A&#x3b2;x-40 levels best predicted future cognitive performance. We highlight potential contributions of A&#x3b2; homeostasis and blood-brain barrier integrity to elevated CSF sTREM2, underscoring novel biomarker associations relevant to disease progression and clinical outcome measures.

Alzheimer Disease

Signalling thresholds and negative B-cell selection in acute lymphoblastic leukaemia.

B cells are selected for an intermediate level of B-cell antigen receptor (BCR) signalling strength: attenuation below minimum (for example, non-functional BCR) or hyperactivation above maximum (for example, self-reactive BCR) thresholds of signalling strength causes negative selection. In &#x223c;25% of cases, acute lymphoblastic leukaemia (ALL) cells carry the oncogenic BCR-ABL1 tyrosine kinase (Philadelphia chromosome positive), which mimics constitutively active pre-BCR signalling. Current therapeutic approaches are largely focused on the development of more potent tyrosine kinase inhibitors to suppress oncogenic signalling below a minimum threshold for survival. We tested the hypothesis that targeted hyperactivation--above a maximum threshold--will engage a deletional checkpoint for removal of self-reactive B cells and selectively kill ALL cells. Here we find, by testing various components of proximal pre-BCR signalling in mouse BCR-ABL1 cells, that an incremental increase of Syk tyrosine kinase activity was required and sufficient to induce cell death. Hyperactive Syk was functionally equivalent to acute activation of a self-reactive BCR on ALL cells. Despite oncogenic transformation, this basic mechanism of negative selection was still functional in ALL cells. Unlike normal pre-B cells, patient-derived ALL cells express the inhibitory receptors PECAM1, CD300A and LAIR1 at high levels. Genetic studies revealed that Pecam1, Cd300a and Lair1 are critical to calibrate oncogenic signalling strength through recruitment of the inhibitory phosphatases Ptpn6 (ref. 7) and Inpp5d (ref. 8). Using a novel small-molecule inhibitor of INPP5D (also known as SHIP1), we demonstrated that pharmacological hyperactivation of SYK and engagement of negative B-cell selection represents a promising new strategy to overcome drug resistance in human ALL.

Amino Acid Motifs

Plasticity of human microglia and brain perivascular macrophages in aging and Alzheimer's disease.

Myeloid cells, including microglia and perivascular macrophages, are central to Alzheimer's disease (AD) neurobiology, yet their role remains incompletely understood. We profiled 832,505 human myeloid cells from the prefrontal cortex of 1,607 donors spanning the lifespan and showing varying degrees of AD neuropathology. We delineated six subclasses comprising 13 transcriptionally distinct subtypes and identified adaptive changes associated with aging and AD progression. Here we show that a disease-associated microglial subtype, characterized by elevated GPNMB expression and enriched for polygenic AD risk, expands with AD pathology and shows increased phagocytic activity. We identify MITF as an upstream regulator required to maintain this microglial state. Cell-cell interaction analyses prioritize APOE-SORL1 and APOE-TREM2 signaling pairs associated with disease progression. Using human and mouse models, we demonstrate that the neuroprotective effects of this microglial subtype depend on TREM2. These findings provide mechanistic insights into myeloid cell function in aging and AD, aiding therapeutic discovery.

Humans

Mannose receptor (MRC1) mediates uptake of dextran by bone marrow-derived macrophages.

Macrophages survey their environment using receptor-mediated endocytosis and pinocytosis. Receptor-mediated endocytosis allows internalization of specific ligands, whereas pinocytosis nonselectively internalizes extracellular fluids and solutes. CRISPR/Cas9 whole-genome screens were used to identify genes regulating constitutive and growth factor-stimulated dextran uptake in murine bone marrow-derived macrophages (BMDM). The mannose receptor c-type 1 (MRC1/CD206) was a top hit in the screen. Targeted gene disruptions of Mrc1 reduced dextran uptake but had little effect on fluid-phase uptake of Lucifer yellow. Other screen hits also differentially affected the uptake of dextran and Lucifer yellow, indicating internalization by separate mechanisms. Visualization of dextran and Lucifer yellow uptake by microscopy showed enrichment of dextran in small puncta, which was inhibitable by mannan, a ligand of MRC1. In contrast, Lucifer yellow predominantly was internalized in larger macropinosomes. In addition, IL4-treated BMDMs internalized more dextran than untreated BMDM correlating with increased MRC1 expression. Therefore, dextran is not an effective marker for pinocytosis in BMDMs since it is internalized by receptor-mediated process. Numerous genes that regulate dextran internalization in primary murine macrophages were identified in the whole-genome screens, which can inform understanding of the regulation of MRC1 expression and MRC1-mediated uptake in macrophages.

Animals

The R203M and D377Y mutations of the nucleocapsid protein promote SARS-CoV-2 infectivity by impairing RIG-I-mediated antiviral signaling.

The viral protein mutations can modify virus-host interactions during virus evolution, and thus alter the extent of infection or pathogenicity. Studies indicate that nucleocapsid (N) protein of SARS-CoV-2 participates in viral genome assembly, intracellular signal regulation and immune interference. However, its biological function in viral evolution is not well understood. SARS-CoV-2&#x2009;N protein mutations were analyzed in Delta, Omicron, and original strains. Two mutations with a methionine (M) residue at site 203 and a tyrosine (Y) residue at site 377 of the N protein were found in Delta strain but not in Omicron and original strains, and promoted SARS-CoV-2 infection therein. Those mutations, R203M and D377Y, enhanced the inhibitory impact of N protein on the impairment of RIG-I-mediated antiviral signaling, such as IRF3 phosphorylation and IFN-&#x3b2; activation. The viral RNA-binding activity of N protein was promoted by these mutations, effectively attenuating the recognition and interaction of RIG-I with viral RNA compared to the original or other variants. The R203M/D377Y mutations thus enhanced the suppressive activity of the N protein on RIG-I-mediated interferon induction both in vitro and in vivo, which in turn promoted viral replication. This study helps to understand the variability of SARS-CoV-2 in regulating host immunity.

SARS-CoV-2

Innovations Toward Immunopeptidomics.

Over the past 30&#xa0;years, immunopeptidomics has grown alongside improvements in mass spectrometry technology, genomics, transcriptomics, T cell receptor sequencing, and immunological assays to identify and characterize the targets of activated T cells. Together, multiple research groups with expertise in immunology, biochemistry, chemistry, and peptide mass spectrometry have come together to enable the isolation and sequence identification of endogenous major histocompatibility complex (MHC)-bound peptides. The idea to apply highly sensitive mass spectrometry techniques to study the landscape of peptide antigens presented by cell surface MHCs was innovative and continues to be successfully used and improved upon to deepen our understanding of how peptide antigens are processed and presented to T cells. Multiple research groups were involved in this bringing immunopeptidomics to the forefront of translational research, and we will highlight the contributions of one of the earliest developers, Professor Donald F. Hunt, and his research group at the University of Virginia. The Hunt laboratory applied cutting edge mass spectroscopy-based immunopeptidomics to study cancer, autoimmunity, transplant rejection, and infectious diseases. Across these diverse research areas, the Hunt laboratory and collaborators would characterize previously unknown MHC peptide-binding motifs and identify immunologically active antigens using ultra sensitive mass spectrometry techniques. Amazingly, many of the MHC-bound peptide antigens discovered in collaborations with the Hunt laboratory were sequenced by mass spectrometry before the completion of the human genome using manual de novo sequencing. In this perspective article, we will chronicle the work of the Hunt laboratory and their many collaborators that would be a major part of the foundation for mass spectrometry-based immunopeptidomics and its application to immunology research.

Animals

Prognostic value and immune landscape implications of using a novel homologous recombination repair pathway signature in prostate cancer: A retrospective cohort study.

ObjectiveAlthough the homologous recombination repair (HRR) pathway plays a critical role in the treatment of prostate cancer, its prognostic value remains incompletely understood. This study aimed to identify HRR pathway-related biomarkers with clinical utility for prognosis prediction and treatment guidance.MethodsWe analyzed genomic data from The Cancer Genome Atlas and Chinese patients with prostate cancer in a retrospective cohort study using a comprehensive multiomics approach to characterize a novel HRR-related prognostic signature and its immune implications.ResultsIn the Chinese cohort, 25.6% of the patients exhibited homologous recombination deficiency scores >42, whereas 27.3% carried &#x2265;1 HRR gene mutation. We established a prognostic HRR signature (homologous recombination deficiency score >32, HRR gene mutations, and Signature 3) associated with poor outcomes. Compared with The Cancer Genome Atlas data, the Chinese cohort demonstrated a higher prevalence of HRR signature. Patients with HRR signatures demonstrated significantly increased genomic instability markers, including segment number, alteration burden, aneuploidy score, and intratumor heterogeneity. The HRR signature was associated with higher neoantigen load but reduced T cell receptor (TCR) evenness. Immunologically, HRR-positive tumors were associated with computationally inferred immune profiles suggestive of reduced immune activity, characterized by depletion of T-helper 17 cell; downregulation of TLR4/PDCD1LG2 expression; and upregulation of ARG1, IFNG, KIR2DL3, and CXCL9. However, these findings are descriptive and require experimental validation.ConclusionOur findings identify a clinically relevant HRR signature that warrants investigation as a potential predictive biomarker for prostate cancer prognosis and treatment response. This biomarker provides new insights for personalized therapy and may help optimize patient outcomes.

Humans

Recognition of vaccinia virus-infected cells by human natural killer cells depends on natural cytotoxicity receptors.

Natural Killer (NK) cells are important in the immune response to a number of viruses; however, the mechanisms used by NK cells to discriminate between healthy and virus-infected cells are only beginning to be understood. Infection with vaccinia virus provokes a marked increase in the susceptibility of target cells to lysis by NK cells, and we show that recognition of the changes in the target cell induced by vaccinia virus infection depends on the natural cytotoxicity receptors NKp30, NKp44, and NKp46. Vaccinia virus infection does not induce expression of ligands for the activating NKG2D receptor, nor does downregulation of major histocompatibility complex class I molecules appear to be of critical importance for altered target cell susceptibility to NK cell lysis. The increased susceptibility to lysis by NK cells triggered upon poxvirus infection depends on a viral gene, or genes, transcribed early in the viral life cycle and present in multiple distinct orthopoxviruses. The more general implications of these data for the processes of innate immune recognition are discussed.

Cell Line

Tracking GAD-specific T-cell expansions in Type 1 diabetes by intradermal GAD-Alum challenge.

Identifying and monitoring autoreactive T cells that drive beta cell destruction remains a major obstacle to developing effective immunotherapies for type 1 diabetes (T1D). These cells are extremely rare in peripheral blood and cannot be accessed directly from the pancreas. We used intradermal injection of Glutamic Acid Decarboxylase (GAD)-Alum to recruit GAD-specific T cells to accessible sites in the skin and skin-draining lymph nodes (LNs), sampled by skin suction blisters and ultrasound-guided LN aspiration. Peripheral blood samples obtained before GAD injection were restimulated with GAD in vitro to detect reactive CD4+ T cells. Single-cell RNA sequencing (scRNAseq) followed by re-expression of selected T cell receptors (TCRs) confirmed antigen specificity. Up to 70% of T cells at the skin injection site were clonally-expanded and 4 of 14 (28%) re-expressed TCRs were GAD-reactive. In LNs 1 of 14 (4%) clonally-expanded TCRs was GAD-reactive, representing ~0.08% of all T-cells. GAD-reactive cells across compartments displayed Th1 and Th17-associated transcription signatures. These results demonstrate the intradermal autoantigen challenge and scRNAseq, enable direct identification and molecular profiling of autoreactive T cells in vivo. This minimally invasive approach provides a powerful platform for tracking antigen-specific T cells to monitor disease activity and evaluate immune interventions in T1D.

Autoimmunity