The transcription cofactor Hopx is required for regulatory T cell function in dendritic cell-mediated peripheral T cell unresponsiveness

Precision unveiled: Synergistic genomic landscapes in breast cancer-Integrating single-cell analysis and decoding drug toxicity for elite prognostication and tailored therapeutics

BACKGROUND

Globally, breast cancer, with diverse subtypes and prognoses, necessitates tailored therapies for enhanced survival rates. A key focus is glutamine metabolism, governed by select genes. This study explored genes associated with T cells and linked them to glutamine metabolism to construct a prognostic staging index for breast cancer patients for more precise medical treatment.

METHODS

Two frameworks, T-cell related genes (TRG) and glutamine metabolism (GM), stratified breast cancer patients. TRG analysis identified key genes via hdWGCNA and machine learning. T-cell communication and spatial transcriptomics emphasized TRG's clinical value. GM was defined using Cox analyses and the Lasso algorithm. Scores categorized patients as TRG_high+GM_high (HH), TRG_high+GM_low (HL), TRG_low+GM_high (LH), or TRG_low+GM_low (LL). Similarities between HL and LH birthed a "Mixed" class and the TRG_GM classifier. This classifier illuminated gene variations, immune profiles, mutations, and drug responses.

RESULTS

Utilizing a composite of two distinct criteria, we devised a typification index termed TRG_GM classifier, which exhibited robust prognostic potential for breast cancer patients. Our analysis elucidated distinct immunological attributes across the classifiers. Moreover, by scrutinizing the genetic variations across groups, we illuminated their unique genetic profiles. Insights into drug sensitivity further underscored avenues for tailored therapeutic interventions.

CONCLUSION

Utilizing TRG and GM, a robust TRG_GM classifier was developed, integrating clinical indicators to create an accurate predictive diagnostic map. Analysis of enrichment disparities, immune responses, and mutation patterns across different subtypes yields crucial subtype-specific characteristics essential for prognostic assessment, clinical decision-making, and personalized therapies. Further exploration is warranted into multiple fusions between metrics to uncover prognostic presentations across various dimensions.

Episomal Vectors for Stable Production of Recombinant Proteins and Engineered Antibodies

There is tremendous interest in the production of recombinant proteins, particularly bispecific antibodies and antibody-drug conjugates for research and therapeutic use. Here, we demonstrate a highly versatile plasmid system that allows the rapid generation of stable Expi293 cell pools by episomal retention of transfected DNA. By linking protein expression to puromycin resistance through an attenuated internal ribosome entry site, we achieve stable cell pools producing proteins of interest. In addition, split intein-split puromycin-mediated selection of two separate protein expression cassettes allows the stable production of bispecific antibody-like molecules or antibodies with distinct C-terminal heavy chain modifications, such as an antigen on one chain and a sortase tag on the other chain. We also use this novel expression system to generate stable Expi293 cell pools that secrete sortase A Δ59 variant Srt4M. Using these reagents, we prepared a site-specific drug-to-antibody ratio of 1 antibody-siRNA conjugate. We anticipate the simple, robust, and rapid stable protein expression systems described here being useful for a wide variety of applications.

Study on the expression changes of lncRNA in patients with systemic lupus erythematosus and its correlation with Treg cells

OBJECTIVES

We initially explored the link between the differentially expressed long non-coding RNAs (lncRNAs) and the number of regulatory T (Treg) cells by detecting the lncRNA expression profiles in patients with systemic lupus erythematosus (SLE), then analyzed the correlation between Treg-related lncRNAs and the clinical features of SLE patients, predicting the mechanism by which lncRNAs regulate the differentiation and development of Treg cells, and provided new ideas for the treatment of SLE.

METHODS

Peripheral blood of 9 active SLE patients were collected and mononuclear cells (PBMCs) were extracted; the lncRNA expression profiles of PBMCs were analyzed by whole transcriptome sequencing. Nine healthy people were used as controls to screen the differentially expressed lncRNAs, to analyze the correlation between lncRNAs and Treg cell number. Pearson test was used to analyze the correlation between lncRNAs and the number of Treg cell, and the correlation between Treg-associated lncRNA and SLEDAI score, ESR, C3, and C4 in SLE patients. The targeted genes of Treg-associated lncRNAs were predicted with miRcode and Targetscan databases and coexpression network.

RESULTS

There were 240 differentially expressed lncRNAs in SLE patients compared with healthy controls, including 134 highly expressed lncRNAs (p < 0.05) and 106 lowly expressed lncRNAs (p < 0.05). The expression of ANKRD44-AS1 (r = 0.7417, p = 0.0222), LINC00200 (r = 0.6960, p = 0.0373), AP001363.2 (r = 0.7766, p = 0.0138), and LINC02824 (r = 0.7893, p = 0.0114) were positively correlated with the number of Treg cell, and the expression of AP000640.1 (r = - 0.7225, p = 0.0279), AC124248.1 (r = - 0.7653, p = 0.0163), LINC00482 (r = - 0.8317, p = 0.0054), and MIR503HG (r = - 0.7617, p < 0.05) were negatively correlated with the number of Treg cell. Among these Treg-associated lncRNAs, the expression of LINC00482 (r = - 0.7348, p < 0.05) and MIR503 HG (r = - 0.7617, p < 0.05) were negatively correlated with C3. LINC00200, ANKRD44 - AS1, and AP000640.1 related to Treg cells regulate the expression of signal transducer and activator of transcription 5 (STAT5), phospholipase D1 (PLD1), homeodomain-only protein X (HOPX), and runt-related transcription factor 3 (RUNX3) through competitive binding of miRNA or trans-regulatory mechanism, thereby regulating the differentiation and development of Treg cell.

CONCLUSIONS

The lncRNA expression profiles were changed in SLE patients, the differentially expressed lncRNAs were associated with abnormal number and function of Treg cells in SLE, and Treg-associated lncRNAs were associated with SLE-disease activity, which may affect the expression of STAT5, PLD1, HOPX, RUNX3 and regulate Treg cell function and participate in the pathogenesis and progression of SLE by competitively binding to miRNAs or trans-regulatory mechanism. Key points • Systemic lupus erythematosus (SLE) is an autoimmune disease involving multiple organs and systems. lncRNAs may affect Treg cells function by regulating genes expression, which may be an important pathogenesis of SLE. • This study, taking SLE as an example, preliminarily analyzed the correlation between lncRNA and Treg cells in SLE patients, analyzed the correlation between Treg-related lncRNA and the clinical characteristics of SLE, and speculated that lncRNA could regulate the differentiation and development of Treg cells through competitive combination with miRNA or trans-regulatory mechanisms. • It is possible to target epigenetic therapy for SLE.

Homeodomain-only protein suppresses proliferation and contributes to differentiation- and age-related reduced CD8+ T cell expansion

T cell activation is a tightly controlled process involving both positive and negative regulators. The precise mechanisms governing the negative regulators in T cell proliferation remain incompletely understood. Here, we report that homeodomain-only protein (HOPX), a homeodomain-containing protein, and its most abundant isoform HOPXb, negatively regulate activation-induced proliferation of human T cells. We found that HOPX expression progressively increased from naïve (TN) to central memory (TCM) to effector memory (TEM) cells, with a notable upregulation following in vitro stimulation. Overexpression of HOPXb leads to a reduction in TN cell proliferation while HOPX knockdown promotes proliferation of TN and TEM cells. Furthermore, we demonstrated that HOPX binds to promoters and exerts repressive effects on the expression of MYC and NR4A1, two positive regulators known to promote T cell proliferation. Importantly, our findings suggest aging is associated with increased HOPX expression, and that knockdown of HOPX enhances the proliferation of CD8+ T cells in older adults. Our findings provide compelling evidence that HOPX serves as a negative regulator of T cell activation and plays a pivotal role in T cell differentiation and in age-related-reduction in T cell proliferation.

Type 2-polarized memory B cells hold allergen-specific IgE memory

Allergen-specific immunoglobulin E (IgE) antibodies mediate pathology in diseases such as allergic rhinitis and food allergy. Memory B cells (MBCs) contribute to circulating IgE by regenerating IgE-producing plasma cells upon allergen encounter. Here, we report a population of type 2-polarized MBCs defined as CD23hi, IL-4Rαhi, and CD32low at both the transcriptional and surface protein levels. These MBC2s are enriched in IgG1- and IgG4-expressing cells while constitutively expressing germline transcripts for IgE. Allergen-specific B cells from patients with allergic rhinitis and food allergy were enriched in MBC2s. Furthermore, MBC2s generated allergen-specific IgE during sublingual immunotherapy, thereby identifying these cells as a major reservoir for IgE. The identification of MBC2s provides insights into the maintenance of IgE memory, which is detrimental in allergic diseases but could be beneficial in protection against venoms and helminths.

EPISOMAL VECTORS FOR STABLE PRODUCTION OF RECOMBINANT PROTEINS AND ENGINEERED ANTIBODIES

There is tremendous interest in the production of recombinant proteins, particularly bispecific antibodies and antibody-drug conjugates for research and therapeutic use. Here, we demonstrate a highly versatile plasmid system that allows rapid generation of stable Expi293 cell pools by episomal retention of transfected DNA. By linking protein expression to puromycin resistance though an attenuated internal ribosome entry site, we achieve stable cell pools producing proteins of interest. In addition, split intein-split puromycin-mediated selection of two separate protein expression cassettes allows the stable production of bispecific antibody-like molecules or antibodies with distinct C-terminal heavy chain modifications, such as an antigen on one chain and a sortase tag on the other chain. We also use this novel expression system to generate stable Expi293 cell pools that secrete sortase A Δ59 variant Srt4M. Using these reagents, we prepared a site-specific drug-to-antibody ratio of 1 antibody-siRNA conjugate. We anticipate the simple, robust, and rapid stable protein expression systems described here being useful for a wide variety of applications.

GZMKhigh CD8+ T effector memory cells are associated with CD15high neutrophil abundance in non-metastatic colorectal tumors and predict poor clinical outcome

CD8⁺ T cells are a major prognostic determinant in solid tumors, including colorectal cancer (CRC). However, understanding how the interplay between different immune cells impacts on clinical outcome is still in its infancy. Here, we describe that the interaction of tumor infiltrating neutrophils expressing high levels of CD15 with CD8⁺ T effector memory cells (T_EM) correlates with tumor progression. Mechanistically, stromal cell-derived factor-1 (CXCL12/SDF-1) promotes the retention of neutrophils within tumors, increasing the crosstalk with CD8⁺ T cells. As a consequence of the contact-mediated interaction with neutrophils, CD8⁺ T cells are skewed to produce high levels of GZMK, which in turn decreases E-cadherin on the intestinal epithelium and favors tumor progression. Overall, our results highlight the emergence of GZMK^high CD8⁺ T_EM in non-metastatic CRC tumors as a hallmark driven by the interaction with neutrophils, which could implement current patient stratification and be targeted by novel therapeutics.

HOPX: A Unique Homeodomain Protein in Development and Tumor Suppression

Simple Summary

Homeobox (HOX) genes encode homeodomain proteins that regulate a wide range of molecular pathways. The homeodomain is highly conserved and binds to DNA. One exception is homeodomain-only protein (HOPX) that lacks DNA-binding capacity. HOPX plays a crucial role in development and its functional impairment is associated with a variety of diseases, including cancer. Loss of HOPX function occurs in a wide range of cancer types, where it functions as a tumor suppressor gene. Understanding the molecular mechanisms by which HOPX regulates carcinogenesis will likely lead to the development of new therapeutic approaches.

Abstract

Homeobox genes are master regulators of morphogenesis and differentiation by acting at the top of genetic hierarchies and their deregulation is associated with a variety of human diseases. They usually contain a highly conserved sequence that codes for the homeodomain of the protein, a specialized motif with three α helices and an N-terminal arm that aids in DNA binding. However, one homeodomain protein, HOPX, is unique among its family members in that it lacks the capacity to bind DNA and instead functions by interacting with transcriptional regulators. HOPX plays crucial roles in organogenesis and is expressed in both embryonic and adult stem cells. Loss of HOPX expression is common in cancer, where it functions primarily as a tumor suppressor gene. In this review, we describe the function of HOPX in development and discuss its role in carcinogenesis.

Gene Expression Profiles of Treatment Response and Non-Response in Children With Juvenile Dermatomyositis

Objective

The study objective was to identify differences in gene expression between treatment responders (TRs) and treatment non‐responders (TNRs) diagnosed with juvenile dermatomyositis (JDM).

Methods

Gene expression analyses were performed using whole blood messenger RNA sequencing in patients with JDM (n = 17) and healthy controls (HCs; n = 10). Four analyses were performed (A1‐4) comparing differential gene expression and pathways analysis exploiting the timing of sample acquisition and the treatments received to perform these comparative analyses. Analyses were done at diagnosis and follow‐up, which averaged 7 months later in the cohort.

Results

At diagnosis, the expression of 10 genes differed between TRs and TNRs. Hallmark and canonical pathway analysis revealed 11 and 60 pathways enriched in TRs and 3 and 21 pathways enriched in TNRs, respectively. Pathway enrichment at diagnosis in TRs was strongest in pathways involved in metabolism, complement activation, and cell signaling as mediated by IL‐8, p38/microtubule associated protein kinases (MAPK)/extracellular signal‐regulated kinases (ERK), Phosphatidylinositol 3 Kinase Gamma (PI3Kγ), and the B cell receptor. Follow‐up hallmark and canonical pathway analysis showed that 2 and 14 pathways were enriched in TRs, whereas 24 and 123 pathways were enriched in treatment TNRs, respectively. Prior treatment with glucocorticoids significantly altered expression of 13 genes in the analysis of subjects at diagnosis with JDM as compared with HCs.

Conclusion

Numerous genes and pathways differ between TRs and TNRs at diagnosis and follow‐up. Prior treatment with glucocorticoids prior to specimen acquisition had a small effect on the performed analyses.

TNF-α sculpts a maturation process in vivo by pruning tolerogenic dendritic cells

It remains unclear how the pro-immunogenic maturation of conventional dendritic cells (cDCs) abrogates their tolerogenic functions. Here, we report that the loss of tolerogenic functions depends on the rapid death of BTLAhi cDC1s, which, in the steady state, are present in systemic peripheral lymphoid organs and promote tolerance that limits subsequent immune responses. A canonical inducer of maturation, lipopolysaccharide (LPS), initiates a burst of tumor necrosis factor alpha (TNF-α) production and the resultant acute death of BTLAhi cDC1s mediated by tumor necrosis factor receptor 1. The ablation of these individual tolerogenic cDCs is amplified by TNF-α produced by neighboring cells. This loss of tolerogenic cDCs is transient, accentuating the restoration of homeostatic conditions through biological turnover of cDCs in vivo. Therefore, our results reveal that the abrogation of tolerogenic functions during an acute immunogenic maturation depends on an ablation of the tolerogenic cDC population, resulting in a dynamic remodeling of the cDC functional landscape.

Downregulated cytotoxic CD8+ T-cell identifies with the NKG2A-soluble HLA-E axis as a predictive biomarker and potential therapeutic target in keloids

Keloids are an abnormal fibroproliferative wound-healing disease with a poorly understood pathogenesis, making it difficult to predict and prevent this disease in clinical settings. Identifying disease-specific signatures at the molecular and cellular levels in both the blood circulation and primary lesions is urgently needed to develop novel biomarkers for risk assessment and therapeutic targets for recurrence-free treatment. There is mounting evidence of immune cell dysregulation in keloid scarring. In this study, we aimed to profile keloid scar tissues and blood cells and found that downregulation of cytotoxic CD8+ T cells is a keloid signature in the peripheral blood and keloid lesions. Single-cell RNA sequencing revealed that the NKG2A/CD94 complex was specifically upregulated, which might contribute to the significant reduction in CTLs within the scar tissue boundary. In addition, the NKG2A/CD94 complex was associated with high serum levels of soluble human leukocyte antigen-E (sHLA-E). We subsequently measured sHLA-E in our hospital-based study cohort, consisting of 104 keloid patients, 512 healthy donors, and 100 patients with an interfering disease. The sensitivity and specificity of sHLA-E were 83.69% (87/104) and 92.16% (564/612), respectively, and hypertrophic scars and other unrelated diseases exhibited minimal interference with the test results. Furthermore, intralesional therapy with triamcinolone combined with 5-fluorouracil drastically decreased the sHLA-E levels in keloid patients with better prognostic outcomes, while an incomplete reduction in the sHLA-E levels in patient serum was associated with higher recurrence. sHLA-E may effectively serve as a diagnostic marker for assessing the risk of keloid formation and a prognostic marker for the clinical outcomes of intralesional treatment.

Variegated Outcomes of T Cell Activation by Dendritic Cells in the Steady State

Conventional dendritic cells (cDC) control adaptive immunity by sensing damage- and pathogen-associated molecular patterns and then inducing defined differentiation programs in T cells. Nevertheless, in the absence of specific proimmunogenic innate signals, generally referred to as the steady state, cDC also activate T cells to induce specific functional fates. Consistent with the maintenance of homeostasis, such specific outcomes of T cell activation in the steady state include T cell clonal anergy, deletion, and conversion of peripheral regulatory T cells (pTregs). However, the robust induction of protolerogenic mechanisms must be reconciled with the initiation of autoimmune responses and cancer immunosurveillance that are also observed under homeostatic conditions. Here we review the diversity of fates and functions of T cells involved in the opposing immunogenic and tolerogenic processes induced in the steady state by the relevant mechanisms of systemic cDC present in murine peripheral lymphoid organs.

Landscape of Hopx expression in cells of the immune system

Homeodomain only protein (Hopx) is a regulator of cell differentiation and function, and it has also emerged as a crucial marker of specific developmental and differentiation potentials. Hopx expression and functions have been identified in some stem cells, tumors, and in certain immune cells. However, expression of Hopx in immune cells remains insufficiently characterized. Here we report a comprehensive pattern of Hopx expression in multiple types of immune cells under steady state conditions. By utilizing single-cell RNA sequencing (scRNA-seq) and flow cytometric analysis, we characterize a constitutive expression of Hopx in specific subsets of CD4⁺ and CD8⁺ T cells and B cells, as well as natural killer (NK), NKT, and myeloid cells. In contrast, Hopx expression is not present in conventional dendritic cells and eosinophils. The utility of identifying expression of Hopx in immune cells may prove vital in delineating specific roles of Hopx under multiple immune conditions.

HOPX+ injury-resistant intestinal stem cells drive epithelial recovery after severe intestinal ischemia

Intestinal ischemia is a life-threatening emergency with mortality rates of 50%-80% due to epithelial cell death and resultant barrier loss. Loss of the epithelial barrier occurs in conditions including intestinal volvulus and neonatal necrotizing enterocolitis. Survival depends on effective epithelial repair; crypt-based intestinal epithelial stem cells (ISCs) are the source of epithelial renewal in homeostasis and after injury. Two ISC populations have been described: 1) active ISC [aISC; highly proliferative; leucine-rich-repeat-containing G protein-coupled receptor 5 (LGR5⁺)-positive or sex-determining region Y-box 9 -antigen Ki67-positive (SOX9⁺Ki67⁺)] and 2) reserve ISC [rISC; less proliferative; homeodomain-only protein X positive (HOPX⁺)]. The contributions of these ISCs have been evaluated both in vivo and in vitro using a porcine model of mesenteric vascular occlusion to understand mechanisms that modulate ISC recovery responses following ischemic injury. In our previously published work, we observed that rISC conversion to an activated state was associated with decreased HOPX expression during in vitro recovery. In the present study, we wanted to evaluate the direct role of HOPX on cellular proliferation during recovery after injury. Our data demonstrated that during early in vivo recovery, injury-resistant HOPX⁺ cells maintain quiescence. Subsequent early regeneration within the intestinal crypt occurs around 2 days after injury, a period in which HOPX expression decreased. When HOPX was silenced in vitro, cellular proliferation of injured cells was promoted during recovery. This suggests that HOPX may serve a functional role in ISC-mediated regeneration after injury and could be a target to control ISC proliferation.NEW & NOTEWORTHY This paper supports that rISCs are resistant to ischemic injury and likely an important source of cellular renewal following near-complete epithelial loss. Furthermore, we have evidence that HOPX controls ISC activity state and may be a critical signaling pathway during ISC-mediated repair. Finally, we use multiple novel methods to evaluate ISCs in a translationally relevant large animal model of severe intestinal injury and provide evidence for the potential role of rISCs as therapeutic targets.

Spleen proteome profiling of dairy goats infected with C. pseudotuberculosis by TMT-based quantitative proteomics approach

Corynebacterium pseudotuberculosis (C.pseudotuberculosis) is a zoonotic pathogen that can cause cheese lymphadenitis in goats. In order to obtain detailed information about the pathogenesis and host immune response of goats infected with C.pseudotuberculosis, we used tandem mass tag (TMT)-labeling proteomic analysis to detect differentially expressed proteins (DEPs) in dairy goats infected with C.pseudotuberculosis, and confirmed the altered proteins with western blot. A total of 6611 trusted proteins were identified, and 126 proteins were differentially abundant. Gene ontology (GO) analysis showed that all DEPs were annotated as biological processes, cell composition, and molecular functions. Biological processes mainly involve acute inflammation and immune response; cell components mainly involve extracellular areas and high-density lipoprotein particles; molecular functions are mainly antigen binding, ferric iron binding, and iron ion binding. KEGG analysis showed that a total of 102 pathways were significantly enriched, mainly lysosomes, phagosomes, and mineral absorption pathways. Our findings provided the relevant knowledge of spleen protein levels in goats infected with C.pseudotuberculosis and revealed the complex molecular pathways and immune response mechanisms in the process of C.pseudotuberculosis infection. SIGNIFICANCE: C.pseudotuberculosis is the most fatal infectious disease in dairy goats, causing huge economic losses. However, the molecular pathways and immune response mechanisms of C.pseudotuberculosis infection in goats remain unclear. Therefore, we conducted a comparative quantitative proteomics study on dairy goats infected with C.pseudotuberculosis. The results provide a basis for better understanding the complexity of C.pseudotuberculosis infection, reveal the complex molecular pathways and immune response mechanisms in C.pseudotuberculosis infection, and provide some clues for identifying potential therapeutic targets. This is the first report to show that C.pseudotuberculosis infection in dairy goats can disrupt the immune response mechanism and lead to massive immune cell death. The study provided new findings on the interaction between C.pseudotuberculosis and the host.

Granulocyte-macrophage colony-stimulating factor mRNA and Neuroprotective Immunity in Parkinson's disease

Restoring numbers and function of regulatory T cells (Tregs) is a novel therapeutic strategy for neurodegenerative disorders. Whether Treg function is boosted by adoptive cell transfer, pharmaceuticals, or immune modulators, the final result is a robust anti-inflammatory and neuronal sparing response. Herein, a newly developed lipid nanoparticle (LNP) containing mRNA encoding granulocyte-macrophage colony-stimulating factor (Gm-csf mRNA) was developed to peripherally induce Tregs and used for treatment in preclinical Parkinson's disease (PD) models. Administration of Gm-csf mRNA to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated mice and rats overexpressing alpha-synuclein produced dose-dependent increases in plasma GM-CSF levels and peripheral CD4+CD25+FoxP3+ Treg populations. This upregulation paralleled nigrostriatal neuroprotection, upregulated immunosuppression-associated mRNAs that led to the detection of a treatment-induced CD4+ T cell population, and decreased reactive microgliosis. The current findings strengthen prior works utilizing immune modulation by harnessing Gm-csf mRNA to augment adaptive immune function by employing a new delivery platform to treat PD and potentially other neurodegenerative disorders.

Systems analysis of human T helper17 cell differentiation uncovers distinct time-regulated transcriptional modules

T helper (Th) 17 cells protect from infections and are pathogenic in autoimmunity. While human Th17 cell differentiation has been defined, the global and stepwise transcriptional changes accompanying this process remain uncharacterized. Herein, by performing transcriptome analysis of human Th17 cells, we uncovered three time-regulated modules: early, involving exclusively “signaling pathways” genes; late, characterized by response to infections; and persistent, involving effector immune functions. To assign them an inflammatory or regulatory potential, we compared Th17 cells differentiated in presence or absence of interleukin (IL)-1β, respectively. Most inflammatory genes belong to the persistent module, whereas regulatory genes are lately or persistently induced. Among inflammatory genes, we identified the effector molecules IL17A, IL17F, IL26, IL6, interferon (IFN)G, IFNK, LTA, IL1A, platelet-derived growth factor (PDGF) A and the transcriptional regulators homeodomain-only protein homeobox (HOPX) and sex-determining-region-Y-box (SOX)2, whose expression was independently validated. This study provides an integrative representation of the stepwise human Th17 differentiation program and offers new perspectives toward therapeutic targeting of Th17-related autoimmune diseases.

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Human Th17 cells are driven by early, late, and persistent transcriptional modules.

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Human Th17 cells express IL17A, IL17F, IL26, IL6, IFNG, IFNK, LTA, IL1A, and PDGFA.

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RORC regulates the IL17A, IL17F, IFNG, PDGFA, and IL1A expression in human Th17 cells.

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HOPX and SOX2 contribute to the expression of IFNG by human Th17 cells.

The role of HOPX in normal tissues and tumor progression

The homeodomain-only protein homeobox (HOPX) as the smallest homeodomain protein, lacks certain conserved residues required for DNA binding. Through our literature search, we reviewed the current understandings of HOPX in normal tissues and tumor progression. HOPX was initially identified as a critical transcription factor in various normal tissues, which interacted with serum response factor (SRF) or other substance to regulate normal physiological function. However, HOPX is at a low expression or methylation level in tumors. These data indicated that HOPX may play a very important role in regulating differentiation phenotype and tumor suppressive function. We predicted the prognosis of HOPX in tumors from TCGA database and discussed the downstream genes of HOPX. To understand how HOPX is involved in the mechanisms between physical and pathological conditions could lead to novel therapeutic strategies for treatment.

A Two-Step Process of Effector Programming Governs CD4+ T Cell Fate Determination Induced by Antigenic Activation in the Steady State

Various processes induce and maintain immune tolerance, but effector T cells still arise under minimal perturbations of homeostasis through unclear mechanisms. We report that, contrary to the model postulating primarily tolerogenic mechanisms initiated under homeostatic conditions, effector programming is an integral part of T cell fate determination induced by antigenic activation in the steady state. This effector programming depends on a two-step process starting with induction of effector precursors that express Hopx and are imprinted with multiple instructions for their subsequent terminal effector differentiation. Such molecular circuits advancing specific terminal effector differentiation upon re-stimulation include programmed expression of interferon-γ, whose production then promotes expression of T-bet in the precursors. We further show that effector programming coincides with regulatory conversion among T cells sharing the same antigen specificity. However, conventional type 2 dendritic cells (cDC2) and T cell functions of mammalian target of rapamycin complex 1 (mTORC1) increase effector precursor induction while decreasing the proportion of T cells that can become peripheral Foxp3⁺ regulatory T (pTreg) cells.

The mechanisms in the steady state that govern the formation of effector T cells with potentially autoimmune functions remain unclear. Opejin et al. reveal a two-step process starting with induction of effector precursors that express Hopx and are imprinted with multiple instructions for their subsequent terminal effector differentiation.

Targeting Dendritic Cells with Antigen-Delivering Antibodies for Amelioration of Autoimmunity in Animal Models of Multiple Sclerosis and Other Autoimmune Diseases

The specific targeting of dendritic cells (DCs) using antigen-delivering antibodies has been established to be a highly efficient protocol for the induction of tolerance and protection from autoimmune processes in experimental autoimmune encephalomyelitis (EAE), a model of multiple sclerosis (MS), as well as in some other animal disease models. As the specific mechanisms of such induced tolerance are being investigated, the newly gained insights may also possibly help to design effective treatments for patients. Here we review approaches applied for the amelioration of autoimmunity in animal models based on antibody-mediated targeting of self-antigens to DCs. Further, we discuss relevant mechanisms of immunological tolerance that underlie such approaches, and we also offer some future perspectives for the application of similar methods in certain related disease settings such as transplantation.

Cellular inflammation in pulmonary hypertension: Detailed analysis of lung and right ventricular tissue, circulating immune cells and effects of a dual endothelin receptor antagonist

Growing evidence suggests that inflammation is crucially involved in the pathogenesis of pulmonary hypertension (PH) and consecutive right heart failure. The present study analyzed the inflammatory response in lung and right ventricle in a rat model of PH and evaluated the effects of the dual endothelin receptor antagonist (ERA) Macitentan. PH was induced by monocrotalin (60 mg/kg body weight s.c.) in Sprague-Dawley rats (PH, n = 10) and compared to healthy controls (CON, n = 10) as well as monocrotalin-induced, macitentan-treated rats (THER, n = 10). Detection of Dendritic cells (DCs), regulatory T cells (Tregs) and others as well as RT-PCR based inflammatory gene expression analysis were performed. Circulating DCs and Tregs were quantified by flow cytometry in the rat model and in PH patients (n = 70) compared to controls (n = 52). Inflammatory cells were increased in lung and right ventricular tissue, whereas DCs and Tregs were decreased in blood. Expression of 17 genes in the lung and 20 genes in the right ventricle were relevantly (>2.0 fold) regulated in the PH group. These effects were, at least in part, attenuated in response to Macitentan treatment. In humans as well as rats, immune cells showed significant correlations to clinical, echocardiographic, and haemodynamic parameters. PH is accompanied by a distinct inflammatory response in lung and right but not left ventricular tissue attenuated by Macitentan. Correlations of circulating DCs as well as tissue resident immune cells with parameters reflecting right ventricular function raise the idea of both, promising biomarkers and novel treatment strategies.

Longitudinal DNA methylation differences precede type 1 diabetes

DNA methylation may be involved in development of type 1 diabetes (T1D), but previous epigenome-wide association studies were conducted among cases with clinically diagnosed diabetes. Using multiple pre-disease peripheral blood samples on the Illumina 450 K and EPIC platforms, we investigated longitudinal methylation differences between 87 T1D cases and 87 controls from the prospective Diabetes Autoimmunity Study in the Young (DAISY) cohort. Change in methylation with age differed between cases and controls in 10 regions. Average longitudinal methylation differed between cases and controls at two genomic positions and 28 regions. Some methylation differences were detectable and consistent as early as birth, including before and after the onset of preclinical islet autoimmunity. Results map to transcription factors, other protein coding genes, and non-coding regions of the genome with regulatory potential. The identification of methylation differences that predate islet autoimmunity and clinical diagnosis may suggest a role for epigenetics in T1D pathogenesis; however, functional validation is warranted.

Preservation of reserve intestinal epithelial stem cells following severe ischemic injury

Intestinal ischemia is an abdominal emergency with a mortality rate >50%, leading to epithelial barrier loss and subsequent sepsis. Epithelial renewal and repair after injury depend on intestinal epithelial stem cells (ISC) that reside within the crypts of Lieberkühn. Two ISC populations critical to epithelial repair have been described: 1) active ISC (aISC; highly proliferative; leucine-rich-repeat-containing G protein-coupled receptor 5 positive, sex determining region Y-box 9 positive) and 2) reserve ISC [rISC; less proliferative; homeodomain only protein X (Hopx)⁺]. Yorkshire crossbred pigs (8-10 wk old) were subjected to 1-4 h of ischemia and 1 h of reperfusion or recovery by reversible mesenteric vascular occlusion. This study was designed to evaluate whether ISC-expressing biomarkers of aISCs or rISCs show differential resistance to ischemic injury and different contributions to the subsequent repair and regenerative responses. Our data demonstrate that, following 3-4 h ischemic injury, aISC undergo apoptosis, whereas rISC are preserved. Furthermore, these rISC are retained ex vivo in spheroids in which cell populations are enriched in the rISC biomarker Hopx. These cells appear to go on to provide a proliferative pool of cells during the recovery period. Taken together, these data indicate that Hopx⁺ cells are resistant to injury and are the likely source of epithelial renewal following prolonged ischemic injury. It is therefore possible that targeting reserve stem cells will lead to new therapies for patients with severe intestinal injury. NEW & NOTEWORTHY The population of reserve less-proliferative intestinal epithelial stem cells appears resistant to injury despite severe epithelial cell loss, including that of the active stem cell population, which results from prolonged mesenteric ischemia. These cells can change to an activated state and are likely indispensable to regenerative processes. Reserve stem cell targeted therapies may improve treatment and outcome of patients with ischemic disease.

Immune checkpoints and the regulation of tolerogenicity in dendritic cells: Implications for autoimmunity and immunotherapy

The immune system is responsible for defending the host from a large variety of potential pathogens, while simultaneously avoiding immune reactivity towards self-components. Self-tolerance has to be tightly maintained throughout several central and peripheral processes; immune checkpoints are imperative for regulating the immunity/tolerance balance. Dendritic cells (DCs) are specialized cells that capture antigens, and either activate or inhibit antigen-specific T cells. Therefore, they play a key role at inducing and maintaining immune tolerance. DCs that suppress the immune response have been called tolerogenic dendritic cells (tolDCs). Given their potential as a therapy to prevent transplant rejection and autoimmune damage, several strategies are under development to generate tolDCs, in order to avoid activation and expansion of self-reactive T cells. In this article, we summarize the current knowledge relative to the main features of tolDCs, their mechanisms of action and their therapeutic use for autoimmune diseases. Based on the literature reviewed, autologous antigen-specific tolDCs might constitute a promising strategy to suppress autoreactive T cells and reduce detrimental inflammatory processes.

Human MAIT cells exit peripheral tissues and recirculate via lymph in steady state conditions

Mucosal-associated invariant T cells (MAIT cells) recognize bacterial metabolites as antigen and are found in blood and tissues, where they are poised to contribute to barrier immunity. Recent data demonstrate that MAIT cells located in mucosal barrier tissues are functionally distinct from their blood counterparts, but the relationship and circulation of MAIT cells between blood and different tissue compartments remains poorly understood. Previous studies raised the possibility that MAIT cells do not leave tissue and may either be retained or undergo apoptosis. To directly address if human MAIT cells exit tissues, we collected human donor-matched thoracic duct lymph and blood and analyzed MAIT cell phenotype, transcriptome, and T cell receptor (TCR) diversity by flow cytometry and RNA sequencing. We found that MAIT cells were present in the lymph, despite being largely CCR7- in the blood, thus indicating that MAIT cells in the lymph migrated from tissues and were capable of exiting tissues to recirculate. Importantly, MAIT cells in the lymph and blood had highly overlapping clonotype usage but distinct transcriptome signatures, indicative of differential activation states.

Modulation of the diet and gastrointestinal microbiota normalizes systemic inflammation and β-cell chemokine expression associated with autoimmune diabetes susceptibility

Environmental changes associated with modern lifestyles may underlie the rising incidence of Type 1 diabetes (T1D). Our previous studies of T1D families and the BioBreeding (BB) rat model have identified a peripheral inflammatory state that is associated with diabetes susceptibility, consistent with pattern recognition receptor ligation, but is independent of disease progression. Here, compared to control strains, islets of spontaneously diabetic BB DRlyp/lyp and diabetes inducible BB DR+/+ weanlings provided a standard cereal diet expressed a robust proinflammatory transcriptional program consistent with microbial antigen exposure that included numerous cytokines/chemokines. The dependence of this phenotype on diet and gastrointestinal microbiota was investigated by transitioning DR+/+ weanlings to a gluten-free hydrolyzed casein diet (HCD) or treating them with antibiotics to alter/reduce pattern recognition receptor ligand exposure. Bacterial 16S rRNA gene sequencing revealed that these treatments altered the ileal and cecal microbiota, increasing the Firmicutes:Bacteriodetes ratio and the relative abundances of lactobacilli and butyrate producing taxa. While these conditions did not normalize the inherent hyper-responsiveness of DR+/+ rat leukocytes to ex vivo TLR stimulation, they normalized plasma cytokine levels, plasma TLR4 activity levels, the proinflammatory islet transcriptome, and β-cell chemokine expression. In lymphopenic DRlyp/lyp rats, HCD reduced T1D incidence, and the introduction of gluten to this diet induced islet chemokine expression and abrogated protection from diabetes. Overall, these studies link BB rat islet-level immunocyte recruiting potential, as measured by β-cell chemokine expression, to a genetically controlled immune hyper-responsiveness and innate inflammatory state that can be modulated by diet and the intestinal microbiota.

Update on Dendritic Cell-Induced Immunological and Clinical Tolerance

Dendritic cells (DCs) as highly efficient antigen-presenting cells are at the interface of innate and adaptive immunity. As such, they are key mediators of immunity and antigen-specific immune tolerance. Due to their functional specialization, research efforts have focused on the characterization of DCs subsets involved in the initiation of immunogenic responses and in the maintenance of tissue homeostasis. Tolerogenic DCs (tolDCs)-based therapies have been designed as promising strategies to prevent and control autoimmune diseases as well as allograft rejection after solid organ transplantation (SOT). Despite successful experimental studies and ongoing phase I/II clinical trials using autologous tolDCs in patients with type 1 diabetes, rheumatoid arthritis, multiple sclerosis, and in SOT recipients, additional basic research will be required to determine the optimal DC subset(s) and conditioning regimens for tolDCs-based treatments in vivo. In this review, we discuss the characteristics of human DCs and recent advances in their classification, as well as the role of DCs in immune regulation and their susceptibility to in vitro or in vivo manipulation for the development of tolerogenic therapies, with a focus on the potential of tolDCs for the treatment of autoimmune diseases and the prevention of allograft rejection after SOT.

Dendritic Cells As Inducers of Peripheral Tolerance

Mechanisms of tolerance initiated in the thymus are indispensable for establishing immune homeostasis, but they may not be sufficient to prevent tissue-specific autoimmune diseases. In the periphery, dendritic cells (DCs) play a crucial tolerogenic role, extending the maintenance of immune homeostasis and blocking autoimmune responses. We review here these essential roles of DCs in orchestrating mechanisms of peripheral T cell tolerance as determined by targeted delivery of defined antigens to DCs in vivo in combination with various genetic modifications of DCs. Further, we discuss how DC functions empowered by specific delivery of T cell antigens could be harnessed for tolerance induction in clinical settings.

Peripherally Induced Regulatory T Cells: Recruited Protectors of the Central Nervous System against Autoimmune Neuroinflammation

Defects in regulatory T cells (Treg cells) aggravate multiple sclerosis (MS) after its onset and the absence of Treg cell functions can also exacerbate the course of disease in an animal model of MS. However, autoimmune neuroinflammation in many MS models can be acutely provoked in healthy animals leading to an activation of encephalitogenic T cells despite the induction of immune tolerance in the thymus including thymically produced (t)Treg cells. In contrast, neuroinflammation can be ameliorated or even completely prevented by the antigen-specific Treg cells formed extrathymically in the peripheral immune system (pTreg cells) during tolerogenic responses to relevant neuronal antigens. This review discusses the specific roles of Treg cells in blocking neuroinflammation, examines the impact of peripheral tolerance and dendritic cells on a relevant regulation of neuroinflammation, and explores some of the most recent advances in elucidation of specific mechanisms of the conversion and function of pTreg cells including the roles of CD5 and Hopx in these processes.

Transient antibody targeting of CD45RC induces transplant tolerance and potent antigen-specific regulatory T cells

Rat and human CD4⁺ and CD8⁺ Tregs expressing low levels of CD45RC have strong immunoregulatory properties. We describe here that human CD45 isoforms are nonredundant and identify distinct subsets of cells. We show that CD45RC is not expressed by CD4⁺ and CD8⁺ Foxp3⁺ Tregs, while CD45RA/RB/RO are. Transient administration of a monoclonal antibody (mAb) targeting CD45RC in a rat cardiac allotransplantation model induced transplant tolerance associated with inhibition of allogeneic humoral responses but maintained primary and memory responses against cognate antigens. Anti-CD45RC mAb induced rapid death of CD45RC^high T cells through intrinsic cell signaling but preserved and potentiated CD4⁺ and CD8⁺ CD45RC^low/- Tregs, which are able to adoptively transfer donor-specific tolerance to grafted recipients. Anti-CD45RC treatment results in distinct transcriptional signature of CD4⁺ and CD8⁺ CD45RC^low/- Tregs. Finally, we demonstrate that anti-human CD45RC treatment inhibited graft-versus-host disease (GVHD) in immune-humanized NSG mice. Thus, short-term anti-CD45RC is a potent therapeutic candidate to induce transplantation tolerance in human.

HOPX hypermethylation promotes metastasis via activating SNAIL transcription in nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is characterized by a high rate of local invasion and early distant metastasis. Increasing evidence indicates that epigenetic abnormalities play important roles in NPC development. However, the epigenetic mechanisms underlying NPC metastasis remain unclear. Here we investigate aberrantly methylated transcription factors in NPC tissues, and we identify the HOP homeobox HOPX as the most significantly hypermethylated gene. Consistently, we find that HOXP expression is downregulated in NPC tissues and NPC cell lines. Restoring HOPX expression suppresses metastasis and enhances chemosensitivity of NPC cells. These effects are mediated by HOPX-mediated epigenetic silencing of SNAIL transcription through the enhancement of histone H3K9 deacetylation in the SNAIL promoter. Moreover, we find that patients with high methylation levels of HOPX exhibit poor clinical outcomes in both the training and validation cohorts. In summary, HOPX acts as a tumour suppressor via the epigenetic regulation of SNAIL transcription, which provides a novel prognostic biomarker for NPC metastasis and therapeutic target for NPC treatment.

Immunomodulatory Functions of BTLA and HVEM Govern Induction of Extrathymic Regulatory T Cells and Tolerance by Dendritic Cells

Dendritic cells (DCs) initiate immunity and also antigen-specific tolerance mediated by extrathymic regulatory T (Treg) cells, yet it remains unclear how DCs regulate induction of such tolerance. Here, we report that efficient induction of Treg cells was instructed by BTLA⁺DEC205⁺CD8⁺CD11c⁺ DCs and the immunomodulatory functions of BTLA. In contrast, T cell activation in steady state by total CD11c⁺ DCs that include a majority of DCs that do not express BTLA did not induce Treg cells and had no lasting impact on subsequent immune responses. Engagement of HVEM, a receptor of BTLA, promoted Foxp3 expression in T cells through upregulation of CD5. In contrast, T cells activated in the absence of BTLA and HVEM-mediated functions remained CD5^lo and therefore failed to resist the inhibition of Foxp3 expression in response to effector cell-differentiating cytokines. Thus, DCs require BTLA and CD5-dependent mechanisms to actively adjust tolerizing T cell responses under steady-state conditions.

Distinct gene expression patterns correlate with developmental and functional traits of iNKT subsets

Invariant natural killer T (iNKT) cells comprise a subpopulation of innate lymphocytes developing in thymus. A new model proposes subdividing murine iNKT cells into iNKT1, 2 and 17 cells. Here, we use transcriptome analyses of iNKT1, 2 and 17 subsets isolated from BALB/c and C57BL/6 thymi to identify candidate genes that may affect iNKT cell development, migration or function. We show that Fcɛr1γ is involved in generation of iNKT1 cells and that SerpinB1 modulates frequency of iNKT17 cells. Moreover, a considerable proportion of iNKT17 cells express IL-4 and IL-17 simultaneously. The results presented not only validate the usefulness of the iNKT1/2/17-concept but also provide new insights into iNKT cell biology.

Homeobox-Only Protein Expression Is a Critical Prognostic Indicator of Pancreatic Neuroendocrine Tumor and Is Regulated by Promoter DNA Hypermethylation

OBJECTIVES

We have identified homeobox-only protein (HOPX) as a tumor suppressor gene in various human cancer, and its expression was reduced by promoter DNA hypermethylation. Homeobox-only protein is strongly expressed on pancreatic islet cells; however, clinical relevance of HOPX expression has remained elusive in pancreatic neuroendocrine tumor (pNET).

METHODS

We investigated 36 patients with pNET who undertook surgical resection between 1988 and 2012 for HOPX expression and DNA methylation to reveal its clinical significance.

RESULTS

(1) Homeobox-only protein is strongly expressed on pancreatic islet cells by immunohistochemistry (IHC). Homeobox-only protein expression was recognized on pNET tumor cells for 1+ in 15, for 2+ in 16, and for 3+ in 5. (2) Homeobox-only protein IHC expression was significantly associated with prognosis (P = 0.03), and survival rate was 37.5%, 70.3%, and 100% in HOPX 1+, 2+, and 3+, respectively. (3) Promoter DNA methylation was quantitatively assessed, and HOPX hypermethylation is found in 6.3%, 11.8%, and 66.7% of G1/G2/G3 pNET, respectively (P = 0.02). (4) Multivariate Cox proportional hazards model identified HOPX IHC expression and HOPX promoter DNA hypermethylation as independent prognostic factors in pNET.

CONCLUSIONS

Homeobox-only protein expression is a critical prognostic indicator of pNET, and its regulation may be made through promoter DNA methylation.

The CD4(+) T cell methylome contributes to a distinct CD4(+) T cell transcriptional signature in Mycobacterium bovis-infected cattle

We hypothesised that epigenetic regulation of CD4⁺ T lymphocytes contributes to a shift toward a dysfunctional T cell phenotype which may impact on their ability to clear mycobacterial infection. Combined RNA-seq transcriptomic profiling and Reduced Representation Bisulfite Sequencing identified 193 significantly differentially expressed genes and 760 differentially methylated regions (DMRs), between CD4⁺ T cells from M. bovis infected and healthy cattle. 196 DMRs were located within 10 kb of annotated genes, including GATA3 and RORC, both of which encode transcription factors that promote T_H2 and T_H17 T helper cell subsets respectively. Gene-specific DNA methylation and gene expression levels for the TNFRSF4 and Interferon-γ genes were significantly negatively correlated suggesting a regulatory relationship. Pathway analysis of DMRs identified enrichment of genes involved in the anti-proliferative TGF-β signaling pathway and TGFB1 expression was significantly increased in peripheral blood leukocytes from TB-infected cattle. This first analysis of the bovine CD4⁺ T cell methylome suggests that DNA methylation directly contributes to a distinct gene expression signature in CD4⁺ T cells from cattle infected with M. bovis. Specific methylation changes proximal to key inflammatory gene loci may be critical to the emergence of a non-protective CD4⁺ T cell response during mycobacterial infection in cattle.

HOPX: The Unusual Homeodomain-Containing Protein

The homeodomain-only protein homeobox (HOPX) is the smallest known member of the homeodomain-containing protein family, atypically unable to bind DNA. HOPX is widely expressed in diverse tissues, where it is critically involved in the regulation of proliferation and differentiation. In human skin, HOPX controls epidermal formation through the regulation of late differentiation markers, and HOPX expression correlates with the level of differentiation in cutaneous pathologies. In mouse skin, Hopx was additionally identified as a lineage tracing marker of quiescent hair follicle stem cells. This review discusses current knowledge of HOPX structure and function in normal and pathological conditions.

TGFβ-dependent expression of PD-1 and PD-L1 controls CD8(+) T cell anergy in transplant tolerance

CD8⁺ T cell anergy is a critical mechanism of peripheral tolerance, poorly investigated in response to immunotherapy. Here, using a pancreatic islet allograft model and CD3 antibody therapy, we showed, by single cell gene profiling, that intragraft CD8⁺ lymphocytes coexpressing granzyme B and perforin were selectively depleted through the Fas/FasL pathway. This step led to long-standing anergy of the remaining CD8⁺ T cells marked by the absence of cytotoxic/inflammatory gene expression also confirmed by transcriptome analysis. This sustained unresponsiveness required the presence of the alloantigens. Furthermore, tissue-resident CD8⁺ lymphocytes produced TGFβ and expressed the inhibitory receptors PD-1 and PD-L1. Blockade of TGFβ downregulated PD-1 and PD-L1 expression and precipitated graft rejection. Neutralizing PD-1, PD-L1 or TGFβRII signaling in T cells also abrogated CD3 antibody-induced tolerance. These studies unravel novel mechanisms underlying CD8⁺ T cell anergy and reveal a cell intrinsic regulatory link between the TGFβ and the PD-1/PD-L1 pathways.

DOI:http://dx.doi.org/10.7554/eLife.08133.001

The immune system is always on guard for signs of infection or cells that have become diseased. When these signs are identified, a subset of white blood cells called CD8⁺ T cells leap into action, multiply in number and then act to eliminate the potential threat. While this response is essential to fighting off infections and other diseases like cancer, it can backfire in people with an organ transplant. Indeed, the CD8⁺ T cells can target and attack the cells of the transplanted organ causing the body to reject the organ.

One way to avoid transplant rejection would be to turn off CD8⁺ T cells that have learned to recognize cells from the transplant. In fact, studies in 2012 and 2013 showed that treating transplanted animals with an antibody that binds T cells protects a transplanted organ from attack. This treatment had to be given after the CD8⁺ T cells had recognized and began targeting the transplanted organ to be effective. But it was not clear exactly how this antibody treatment protected the transplant.

Now, Baas, Besançon et al. – including some of the same researchers involved in the earlier studies – show that the antibodies used in the treatment selectively target and eliminate the attacking CD8⁺ T cells. This leaves behind only inactive CD8⁺ T cells that don’t harm the transplant. To do this, Baas, Besançon et al. transplanted pancreatic cells from mice into other mice with a diabetes-like disorder. Next, the experiments compared gene expression in CD8⁺ T cells found within the transplanted tissue in mice that were treated with the antibody and those that were not treated. The expression of many genes for toxic molecules was stopped after treatment with the antibody leaving the CD8⁺ T cells in an inactive state.

In addition, the treated CD8⁺ T cells expressed more of a certain type of receptor (called PD-1 and PD-L1) that acts as inhibitory checkpoint for the immune system. So, Baas, Besançon et al. treated transplanted mice with both the T cell-eliminating antibody and antibodies that block these inhibitory receptors to see what would happen. The transplanted organs were quickly attacked and rejected. This shows that the inhibitory receptors play a crucial role in helping to shut down attacking CD8⁺ T cells in the initial antibody treatment and allowed long-term survival of the transplanted organs. Blocking another protein called TGFβ in antibody-treated mice also caused organ rejection. The findings help explain how these antibodies protect transplanted organs and may help scientists trying to develop new anti-transplant rejection drugs in the future.

DOI:http://dx.doi.org/10.7554/eLife.08133.002

Peripherally Induced Tolerance Depends on Peripheral Regulatory T Cells That Require Hopx To Inhibit Intrinsic IL-2 Expression

Dendritic cells (DCs) can induce peripheral immune tolerance that prevents autoimmune responses. Ag presentation by peripheral DCs under steady-state conditions leads to a conversion of some peripheral CD4(+) T cells into regulatory T cells (Tregs) that require homeodomain-only protein (Hopx) to mediate T cell unresponsiveness. However, the roles of these peripheral Tregs (pTregs) in averting autoimmune responses, as well as immunological mechanisms of Hopx, remain unknown. We report that Hopx(+) pTregs converted by DCs from Hopx(-) T cells are indispensible to sustain tolerance that prevents autoimmune responses directed at self-Ags during experimental acute encephalomyelitis. Our studies further reveal that Hopx inhibits intrinsic IL-2 expression in pTregs after antigenic rechallenge. In the absence of Hopx, increased levels of IL-2 lead to death and decreased numbers of pTregs. Therefore, formation of Hopx(+) pTregs represents a crucial pathway of sustained tolerance induced by peripheral DCs, and the maintenance of such pTregs and tolerance requires functions of Hopx to block intrinsic IL-2 production in pTregs.

The homeobox only protein homeobox (HOPX) and colorectal cancer

The HOP (homeobox only protein) homeobox (HOPX) is most closely related to the homeobox protein that contains a homeobox-like domain but lacks certain conserved residues required for DNA binding. Here, we review the current understanding of HOPX in the progression of colorectal cancer (CRC). HOPX was initially reported as a differentiation marker and is expressed in various normal tissues. In the colon, HOPX is expressed uniquely in the quiescent stem cell, +4, and in differentiated mucosal cells of the colon. HOPX expression is markedly suppressed in a subset of cancers, mainly in an epigenetic manner. CRC may include separate entities which are differentially characterized by HOPX expression from a prognostic point of view. HOPX itself can regulate epigenetics, and defective expression of HOPX can result in loss of tumor suppressive function and differentiation phenotype. These findings indicate that HOPX may be both a central regulator of epigenetic dynamics and a critical determinant for differentiation in human cells. HOPX downstream targets were identified in CRC cell lines and hold promise as candidates for therapeutic targets of CRC, such as EphA2 or AP-1. Further analysis will elucidate and confirm the precise role of such proteins in CRC progression.

Intratumoral regulatory T cells with higher prevalence and more suppressive activity in hepatocellular carcinoma patients

Regulatory T cells (Treg) play a vital role in immunosuppressive crosstalk; however, Tregs from different locations lead to different clinical outcomes. Our aim was, therefore, to compare the prevalences and suppressive phenotypes of Tregs in the peripheral blood, peritumor, and intratumor of patients with hepatocellular carcinoma (HCC). METHODS : The frequencies and phenotypes of CD4(+) CD25(+) CD127(low/-) CD49d(-) Tregs in the periphery, peritumor, and intratumor of 78 HCC patients and 12 healthy controls were evaluated by flow cytometry. Treg-cell suppressive activity was determined using an in vitro CD154 expression assay. Tregs from tumor and paired peritumor were then hybridized using an Agilent whole genome oligo microarray, and selected genes were validated by real-time polymerase chain reaction. Functional analysis of the microarray data was performed using Kyoto Encyclopedia of Genes and Genomes and Gene Ontology analyses. RESULTS : Intratumoral Tregs exhibited higher frequencies and more suppressive phenotypic functions than those in peritumor and periphery, whereas there was no difference between the latter two. Functional analysis showed that complement cascades, p53, and glycosylphosphatidylinositol-anchor biosynthesis pathways were significantly upregulated in intratumoral Tregs; the salivary secretion pathway was significantly downregulated in intratumoral Tregs, and immune cells and tumor-immuno-related Gene Ontology terms were significantly affected. CONCLUSIONS : Tregs in different locations exhibited different functional statuses. A higher prevalence and more suppressive phenotype suggested a critical role for intratumoral Tregs in the formation of multicellular immunosuppressive networks. HCC immunotherapy may be improved, therefore, by specific locational Tregs elimination or suppression.

Temporal induction of immunoregulatory processes coincides with age-dependent resistance to viral-induced type 1 diabetes

The dilute plasma cytokine milieu associated with type 1 diabetes (T1D), while difficult to measure directly, is sufficient to drive transcription in a bioassay that uses healthy leukocytes as reporters. Previously, we reported disease-associated, partially IL-1 dependent, transcriptional signatures in both T1D patients and the BioBreeding (BB) rat model. Here, we examine temporal signatures in congenic BBDR.lyp/lyp rats that develop spontaneous T1D, and BBDR rats where T1D progresses only after immunological perturbation in young animals. After weaning, the BBDR temporal signature showed early coincident induction of transcription related to innate inflammation as well as IL-10- and TGF-β-mediated regulation. BBDR plasma cytokine levels mirrored the signatures showing early inflammation, followed by induction of a regulated state that correlated with failure of virus to induce T1D in older rats. In contrast, the BBDR.lyp/lyp temporal signature exhibited asynchronous dynamics, with delayed induction of inflammatory transcription and later, weaker induction of regulatory transcription, consistent with their deficiency in regulatory T cells. Through longitudinal analyses of plasma-induced signatures in BB rats and a human T1D progressor, we have identified changes in immunoregulatory processes that attenuate a preexisting innate inflammatory state in BBDR rats, suggesting a mechanism underlying the decline in T1D susceptibility with age.

MHC multimer-guided and cell culture-independent isolation of functional T cell receptors from single cells facilitates TCR identification for immunotherapy

Adoptive therapy using T cells redirected to target tumor- or infection-associated antigens is a promising strategy that has curative potential and broad applicability. In order to accelerate the screening process for suitable antigen-specific T cell receptors (TCRs), we developed a new approach circumventing conventional in vitro expansion-based strategies. Direct isolation of paired full-length TCR sequences from non-expanded antigen-specific T cells was achieved by the establishment of a highly sensitive PCR-based T cell receptor single cell analysis method (TCR-SCAN). Using MHC multimer-labeled and single cell-sorted HCMV-specific T cells we demonstrate a high efficacy (approximately 25%) and target specificity of TCR-SCAN receptor identification. In combination with MHC-multimer based pre-enrichment steps, we were able to isolate TCRs specific for the oncogenes Her2/neu and WT1 even from very small populations (original precursor frequencies of down to 0.00005% of CD3(+) T cells) without any cell culture step involved. Genetic re-expression of isolated receptors demonstrates their functionality and target specificity. We believe that this new strategy of TCR identification may provide broad access to specific TCRs for therapeutically relevant T cell epitopes.

Intestinal stem cells - types and markers

Intestinal epithelium is a rapidly cycling tissue, always renewing every 4-5 days under normal conditions, which is maintained by intestinal stem cells (ISCs). Using the fluorescence labelling trace, ISCs can be divided into two different types: active intestinal stem cells (A-ISCs) located in bottom of the intestinal crypt and the quiescent intestinal stem cells (Q-ISCs) in the +4 position of the crypt. There is a complex signal regulation net between the ISCs and other intestinal cells, such as Wnt and Notch pathways. ISCs have an intimate relationship with the colorectal cancer (CRC). However, a deficiency of stem cells markers severely limits research on the biological characteristics of ISCs. We have reviewed several ISCs markers, including Lgr5, PHLDA1, Bmi1 and Lrig1. These markers have widely different biological functions, but also have a close relationship with cancers, especially CRC. Our hypothesis concerns the reasons for ISCs having two distinct types and why endless ISCs markers have emerged.

Molecular definition of the identity and activation of natural killer cells

Using whole-genome microarray data sets of the Immunological Genome Project, we demonstrate a closer transcriptional relationship between NK cells and T cells than between any other leukocytes, distinguished by their shared expression of genes encoding molecules with similar signaling functions. Whereas resting NK cells are known to share expression of a few genes with cytotoxic CD8(+) T cells, our transcriptome-wide analysis demonstrates that the commonalities extend to hundreds of genes, many encoding molecules with unknown functions. Resting NK cells demonstrate a 'preprimed' state compared with naive T cells, which allows NK cells to respond more rapidly to viral infection. Collectively, our data provide a global context for known and previously unknown molecular aspects of NK cell identity and function by delineating the genome-wide repertoire of gene expression of NK cells in various states.

Synchronization of dendritic cell activation and antigen exposure is required for the induction of Th1/Th17 responses

The dendritic cell (DC) targeting/activation patterns required to elicit Th1/Th17 responses remain undefined. One postulated requirement was that of a physical linkage between Ags and immunomodulators. Accordingly, the separate same-site administration of Ag85B-ESAT-6 (hybrid-1 protein; H1), a mycobacterial fusion Ag, and the CAF01 liposome-based adjuvant induced similar Ab and weak Th2 responses as those of coformulated H1/CAF01 but failed to elicit Th1/Th17 responses. Yet, this separate same-site injection generated the same type and number of activated Ag(+)/adjuvant(+) DCs in the draining lymph nodes (LN) as that of protective H1/CAF01 immunization. Thus, targeting/activating the same DC population by Ag and adjuvant is not sufficient to elicit Th1/Th17 responses. To identify the determinants of Th1/Th17 adjuvanticity, in vivo tracking experiments using fluorescently labeled Ag and adjuvant identified that a separate same-site administration elicits an additional early Ag(+)/adjuvant(-) DC population with a nonactivated phenotype, resulting from the earlier targeting of LN DCs by H1 than by CAF01 molecules. This asynchronous targeting pattern was mimicked by the injection of free H1 prior to or with, but not after, H1/CAF01 or H1/CpG/ aluminum hydroxide immunization. The injection of soluble OVA similarly prevented the induction of Th1 responses by OVA/CAF01. Using adoptively transferred OT-2 cells, we show that the Ag targeting of LN DCs prior to their activation generates nonactivated Ag-pulsed DCs that recruit Ag-specific T cells, trigger their initial proliferation, but interfere with Th1 induction in a dose-dependent manner. Thus, the synchronization of DC targeting and activation is a critical determinant for Th1/Th17 adjuvanticity.

Plasticity of T(reg) cells: is reprogramming of T(reg) cells possible in the presence of FOXP3?

Regulatory T cells (T(reg) cells) are involved in self tolerance, immune homeostasis, prevention of autoimmunity, and suppression of immunity to pathogens or tumors. The forkhead transcription factor FOXP3 is essential for T(reg)-cell development and function as mutations in FOXP3 cause severe autoimmune diseases in mice and humans. Over the last years it has been postulated that FOXP3 expression in T(reg) prevents effector T-cell (T(effector)-cell) lineage commitment, yet several recent studies suggest that the co-existence of effector and regulatory T-cell programs can occur and might help to enable T(reg) cells with properties necessary to exert their function in peripheral tissues. Furthermore, downregulation of FOXP3 in the periphery might help T(reg) cells to lose suppressive functions and gain memory properties with specificity for self-antigens and an effector phenotype including the ability to produce IFN-γ and IL-17. This plasticity might have an impact on their reactivity towards autoimmunity as well as tumors or infections.

FOXP3 and RORγt: transcriptional regulation of Treg and Th17

FOXP3(+)CD4(+)CD25(+) Regulatory T (Treg) cells and IL-17 producing helper T cells (Th17) are critical subsets of T cells which play essential roles in immune homeostasis. The Forkhead family transcription factor FOXP3 is predominantly expressed in Treg cells, where the FOXP3 ensemble is essential for Treg cell development and function. As FOXP3 is to Treg cells, the orphan retinoic acid nuclear receptor (ROR) family transcription factor RORγt is essential for Th17 development and function. In this review, we summarize recent progress of our understanding towards the molecular mechanisms underlying the differentiation and function of FOXP3(+) Treg cells and RORγt expressing Th17 cells. These may provide new insights into therapeutic intervention and targeting of human immune-deficient diseases.