Expression and function of NKRP1A molecule on human monocytes and dendritic cells

Identification of immune-related genes in diagnosing retinopathy of prematurity with sepsis through bioinformatics analysis and machine learning

Background: There is increasing evidence indicating that immune system dysregulation plays a pivotal role in the pathogenesis of retinopathy of prematurity (ROP) and sepsis. This study aims to identify key diagnostic candidate genes in ROP with sepsis. Methods: We obtained publicly available data on ROP and sepsis from the gene expression omnibus database. Differential analysis and weighted gene correlation network analysis (WGCNA) were performed to identify differentially expressed genes (DEGs) and key module genes. Subsequently, we conducted functional enrichment analysis to gain insights into the biological functions and pathways. To identify immune-related pathogenic genes and potential mechanisms, we employed several machine learning algorithms, including Support Vector Machine Recursive Feature Elimination (SVM-RFE), Least Absolute Shrinkage and Selection Operator (LASSO), and Random Forest (RF). We evaluated the diagnostic performance using nomogram and Receiver Operating Characteristic (ROC) curves. Furthermore, we used CIBERSORT to investigate immune cell dysregulation in sepsis and performed cMAP analysis to identify potential therapeutic drugs. Results: The sepsis dataset comprised 352 DEGs, while the ROP dataset had 307 DEGs and 420 module genes. The intersection between DEGs for sepsis and module genes for ROP consisted of 34 genes, primarily enriched in immune-related pathways. After conducting PPI network analysis and employing machine learning algorithms, we pinpointed five candidate hub genes. Subsequent evaluation using nomograms and ROC curves underscored their robust diagnostic potential. Immune cell infiltration analysis revealed immune cell dysregulation. Finally, through cMAP analysis, we identified some small molecule compounds that have the potential for sepsis treatment. Conclusion: Five immune-associated candidate hub genes (CLEC5A, KLRB1, LCN2, MCEMP1, and MMP9) were recognized, and the nomogram for the diagnosis of ROP with sepsis was developed.

ILC3: a case of conflicted identity

Innate lymphoid cells type 3 (ILC3s) are the first line sentinels at the mucous tissues, where they contribute to the homeostatic immune response in a major way. Also, they have been increasingly appreciated as important modulators of chronic inflammatory and autoimmune responses, both locally and systemically. The proper identification of ILC3 is of utmost importance for meaningful studies on their role in immunity. Flow cytometry is the method of choice for the detection and characterization of ILC3. However, the analysis of ILC3-related papers shows inconsistency in ILC3 phenotypic definition, as different inclusion and exclusion markers are used for their identification. Here, we present these discrepancies in the phenotypic characterization of human and mouse ILC3s. We discuss the pros and cons of using various markers for ILC3 identification. Furthermore, we consider the possibilities for the efficient isolation and propagation of ILC3 from different organs and tissues for in-vitro and in-vivo studies. This paper calls upon uniformity in ILC3 definition, isolation, and propagation for the increased possibility of confluent interpretation of ILC3's role in immunity.

The prognostic significance of KLRB1 and its further association with immune cells in breast cancer

Background

Killer cell lectin-like receptor B1 (KLRB1) is an important member of the natural killer cell gene family. This study explored the potential value of KLRB1 as a breast cancer (BC) biomarker and its close association with the tumor immune microenvironment during the development of BC.

Methods

We examined the differential expression of KLRB1 in pan-cancer. Clinical and RNA-Seq data from BC samples were evaluated in The Cancer Genome Atlas (TCGA) and validated in Gene Expression Omnibus (GEO) datasets and by immunohistochemistry (IHC) staining. The relationship between KLRB1 and clinical parameters was explored through Chi-square tests. The diagnostic value of KLRB1 was evaluated using a receiver operating characteristic (ROC) curve. Survival analysis was tested by Kaplan-Meier curves to demonstrate the relationship between KLRB1 and survival. Univariable and multivariate cox regression analyses were carried out as well. The analysis of immune infiltration level and gene set enrichment analysis (GSEA) were conducted to examine KLRB1's mechanism during the progression of BC. We used the Tumor Immune Estimation Resource (TIMER), the Cancer Single-cell Expression Map (CancerSCEM) database, the Tumor Immune Single-cell Hub (TISCH) database, and the Cell-type Identification by Estimating Relative Subsets of RNA Transcripts (CIBERSORT) method to explore KLRB1's association with immune infiltration level and different quantitative distribution of immune cells. The relevant signaling pathways in BC associated with KLRB1 were identified using GSEA.

Results

The expression of KLRB1 was downregulated across the majority of cancers including BC. The lower KLRB1 expression group exhibited shorter relapse free survival (RFS) and overall survival (OS). IHC staining showed that KLRB1 staining was weaker in breast tumor tissues than in paratumors. Additionally, GSEA identified several pathway items distinctly enriched in BC. KLRB1 expression level was also positively related to the infiltrating number of immune cells in BC. Moreover, the CancerSCEM and TISCH databases as well as the CIBERSORT method demonstrated the close relationship between KLRB1 and immune cells, particularly macrophages.

Conclusion

Low KLRB1 expression was considered an independent prognostic biomarker and played an important role in the tumor immune microenvironment of BC patients.

Multimodal control of dendritic cell functions by nociceptors

It is known that interactions between nociceptors and dendritic cells (DCs) can modulate immune responses in barrier tissues. However, our understanding of the underlying communication frameworks remains rudimentary. Here, we show that nociceptors control DCs in three molecularly distinct ways. First, nociceptors release the calcitonin gene-related peptide that imparts a distinct transcriptional profile on steady-state DCs characterized by expression of pro-interleukin-1β and other genes implicated in DC sentinel functions. Second, nociceptor activation induces contact-dependent calcium fluxes and membrane depolarization in DCs and enhances their production of proinflammatory cytokines when stimulated. Finally, nociceptor-derived chemokine CCL2 contributes to the orchestration of DC-dependent local inflammation and the induction of adaptive responses against skin-acquired antigens. Thus, the combined actions of nociceptor-derived chemokines, neuropeptides, and electrical activity fine-tune DC responses in barrier tissues.

The immune cell profile of the developing rat brain

Little is known about the peripheral immune cell (PIC) profile of the developing brain despite growing appreciation for these cells in the mature nervous system. To address this gap, the PIC profile, defined as which cells are present, where they are located, and for how long, was examined in the developing rat using spectral flow cytometry. Select regions of the rat brain (cerebellum, hippocampus, and hypothalamus) were examined at embryonic day 20, and postnatal days 0, 7 and 16. At their peak (E20), PICs were most abundant in the cerebellum, then the hippocampus and hypothalamus. Within the PIC pool, monocytes were most prevalent in all regions and time points, and shifted from being majority classical at E20 to non-classical by PN7. T cells increased over time, and shifted from majority cytotoxic to T-helper cells by PN7. This suggests the PIC profile transitions from reactive to adaptive and surveilling in the second postnatal week. NK cells and mast cells increased temporarily, and mast cells were restricted to the hippocampus and hypothalamus, suggesting they may play a specific role in the development of those regions. Mimicking a viral infection by administration of Poly I:C increased the influx of PICs into the neonatal brain, particularly of NK cells and in the case of males only, non-classical monocytes. This work provides a map for researchers as they study immune cell contributions to healthy and pathological brain development.

Natural killer cells and immune-checkpoint inhibitor therapy: Current knowledge and new challenges

The discovery of immune checkpoints (ICs) and the development of specific blockers to relieve immune effector cells from this inhibiting mechanism has changed the view of anti-cancer therapy. In addition to cytotoxic T lymphocyte antigen 4 (CTLA4) and programmed death 1 (PD1), classical ICs of T lymphocytes and recently described also on a fraction of natural killer (NK) cells, several NK cell receptors, including killer immunoglobulin-like inhibitory receptors (KIRs) and NGK2A, have been recognized as checkpoint members typical of the NK cell population. This offers the opportunity of a dual-checkpoint inhibition approach, targeting classical and non-classical ICs and leading to a synergistic therapeutic effect. In this review, we will overview and discuss this new perspective, focusing on the most relevant candidates for this role among the variety of potential NK ICs. Beside listing and defining classical ICs expressed also by NK cells, or non-classical ICs either on T or on NK cells, we will address their role in NK cell survival, chronic stimulation or functional exhaustion, and the potential relevance of this phenomenon on anti-tumor immune response. Furthermore, NK ICs will be proposed as possible new targets for the development of efficient combined immunotherapy, not forgetting the relevant concerns that may be raised on NK IC blockade. Finally, the impact of epigenetic drugs in such a complex therapeutic picture will be briefly addressed.

Systematic Pan-Cancer Analysis of KLRB1 with Prognostic Value and Immunological Activity across Human Tumors

Introduction

KLRB1 is a gene encoding CD161 expressed in NK cells and some T cell subsets. At present, KLRB1 is believed to affect tumorigenesis and development by regulating the cytotoxicity of NK cells in several cancers. However, there is a lack of systematic reviews of KLRB1 in a variety of malignancies.

Objectives

Hence, our research is aimed at providing a relatively comprehensive understanding of the role of KLRB1 in different types of cancer, paving the way for further research on the molecular mechanism and immunotherapy potential of KLRB1.

Methods

In this study, we used relevant public databases, including TCGA (The Cancer Genome Atlas), GEO (Gene Expression Omnibus), CCLE (Cancer Cell Line Encyclopedia), GTEx (Genotype Tissue-Expression), and HPA (Human Protein Atlas), to perform a pan-cancer analysis of KLRB1 across 33 types of cancer. We explored the potential molecular mechanism of KLRB1 in clinical prognosis and tumor immunity from the aspects of gene expression, survival status, clinical phenotype, immune infiltration, immunotherapy response, and chemotherapeutic drug sensitivity.

Results

KLRB1 was downregulated in 13 cancers while upregulated in kidney cancer. Patients with high expression of KLRB1 have a better prognosis in most types of cancer. Moreover, the KLRB1 expression level is related to TMB and MSI and related to various immune signatures of tumor. The expression of KLRB1 can affect tumor immune cell infiltration. KLRB1 expression level can also affect the sensitivity of chemotherapy drugs.

Conclusions

KLRB1 may be a prognostic and immunological biomarker across tumors. At the same time, KLRB1 expression can reflect the sensitivity of cancer patients to chemotherapy drugs. KLRB1 may become a new target for immunotherapy.

CD8+CD161+ T-Cells: Cytotoxic Memory Cells With High Therapeutic Potential

NK1.1 and its human homolog CD161 are expressed on NK cells, subsets of CD4⁺ and CD8⁺ T cells, and NKT cells. While the expression of NK1.1 is thought to be inhibitory to NK cell function, it is reported to play both costimulatory and coinhibitory roles in T-cells. CD161 has been extensively studied and characterized on subsets of T-cells that are MR1-restricted, IL-17 producing CD4⁺ (T_H17 MAIT cells) and CD8⁺ T cells (Tc17 cells). Non-MAIT, MR1-independent CD161-expressing T-cells also exist and are characterized as generally effector memory cells with a stem cell like phenotype. Gene expression analysis of this enigmatic subset indicates a significant enhancement in the expression of cytotoxic granzyme molecules and innate like stress receptors in CD8⁺NK1.1⁺/CD8⁺CD161⁺ cells in comparison to CD8⁺ cells that do not express NK1.1 or CD161. First identified and studied in the context of viral infection, the role of CD8⁺CD161⁺ T-cells, especially in the context of tumor immunology, is still poorly understood. In this review, the functional characteristics of the CD161-expressing CD8⁺ T cell subset with respect to gene expression profile, cytotoxicity, and tissue homing properties are discussed, and application of this subset to immune responses against infectious disease and cancer is considered.

Differential Expression of TOM34, AL1A1, PADI2 and KLRBA in NNK Induced Lung Cancer in Wistar Rats and their Implications

BACKGROUND

Lung cancer is the most common cancer with a high mortality rate. The diagnosis only at advanced stages and lack of effective treatment are the main factors responsible for high mortality. Tobacco smoke is the major responsible factor for inflammation and tumor development in lungs.

OBJECTIVE

The present study was carried out to identify differentially expressed proteins and elucidate their role in carcinogenesis.

METHODS

The lung cancer was developed in Wistar rats by using NNK as carcinogen and cancer development was confirmed by histopathological examination. The 2D SDS PAGE was used to analyse total proteins and find out differentially expressed proteins in NNK treated lung tissue vis-a-vis control tissue. The findings of proteomic analysis were further validated by quantification of corresponding transcripts using Real Time PCR. Finally, Cytoscape was used to find out protein-protein interaction.

RESULTS

The histopathological examinations showed neoplasia at 9th month after NNK treatment. The proteomic analysis revealed several differentially expressed proteins, four of which were selected for further studies. (TOM34, AL1A1, PADI2 and KLRBA) that were up regulated in NNK treated lung tissue. The real time analysis showed over expression of the genes coding for the selected proteins. Thus, the proteomic and transcriptomic data corroborate each other. Further, these proteins showed interaction with the members of NF-κB family and STAT3.

CONCLUSION

We conclude that these proteins play a substantial role in the induction of lung cancer through NF-κB and STAT3 pathway. Therefore, these may have the potential to be used as therapeutic targets and for early detection of lung cancer.

Comprehensive mapping of immune perturbations associated with severe COVID-19

Although critical illness has been associated with SARS-CoV-2-induced hyperinflammation, the immune correlates of severe COVID-19 remain unclear. Here, we comprehensively analyzed peripheral blood immune perturbations in 42 SARS-CoV-2 infected and recovered individuals. We identified extensive induction and activation of multiple immune lineages, including T cell activation, oligoclonal plasmablast expansion, and Fc and trafficking receptor modulation on innate lymphocytes and granulocytes, that distinguished severe COVID-19 cases from healthy donors or SARS-CoV-2-recovered or moderate severity patients. We found the neutrophil to lymphocyte ratio to be a prognostic biomarker of disease severity and organ failure. Our findings demonstrate broad innate and adaptive leukocyte perturbations that distinguish dysregulated host responses in severe SARS-CoV-2 infection and warrant therapeutic investigation.

Immunologic perturbations in severe COVID-19/SARS-CoV-2 infection

Although critical illness has been associated with SARS-CoV-2-induced hyperinflammation, the immune correlates of severe COVID-19 remain unclear. Here, we comprehensively analyzed peripheral blood immune perturbations in 42 SARS-CoV-2 infected and recovered individuals. We identified broad changes in neutrophils, NK cells, and monocytes during severe COVID-19, suggesting excessive mobilization of innate lineages. We found marked activation within T and B cells, highly oligoclonal B cell populations, profound plasmablast expansion, and SARS-CoV-2-specific antibodies in many, but not all, severe COVID-19 cases. Despite this heterogeneity, we found selective clustering of severe COVID-19 cases through unbiased analysis of the aggregated immunological phenotypes. Our findings demonstrate broad immune perturbations spanning both innate and adaptive leukocytes that distinguish dysregulated host responses in severe SARS-CoV-2 infection and warrant therapeutic investigation.

One Sentence Summary

Broad immune perturbations in severe COVID-19.

The killer cell lectin-like receptor B1 (KLRB1) 503T>C polymorphism (rs1135816) and acute rejection after liver transplantation

The killer cell lectin-like receptor B1 (KLRB1) gene encodes for CD161 expressed by different subsets of leukocytes involved in the development of acute liver transplant rejection. The single nucleotide polymorphism (SNP) 503T>C (rs1135816) in the KLRB1 gene represents a missense mutation modifying functional properties of CD161. The aim of our study is to determine whether the SNP 503T>C is associated with acute liver transplant rejection. We genotyped the SNP for 163 liver recipients without acute rejection, 125 recipients with a single acute rejection, and 53 recipients with multiple acute rejections. The genotype frequencies within the groups did not show any significant difference. Our data suggest that the SNP 503T>C has no impact on the susceptibility of acute liver transplant rejection.

CD161 Expression Defines a Th1/Th17 Polyfunctional Subset of Resident Memory T Lymphocytes in Bronchoalveolar Cells

Alveolar resident memory T cells (T_RM) comprise a currently uncharacterized mixture of cell subpopulations. The CD3⁺CD161⁺ T cell subpopulation resides in the liver, intestine and skin, but it has the capacity for tissue migration; however, the presence of resident CD3⁺CD161⁺ T cells in the bronchoalveolar space under normal conditions has not been reported. Bronchoalveolar cells (BACs) from healthy volunteers were evaluated and found that 8.6% (range 2.5%-21%) of these cells were CD3⁺ T lymphocytes. Within the CD3⁺ population, 4.6% of the cells (2.1–11.3) expressed CD161 on the cell surface, and 74.2% of the CD161⁺CD3⁺ T cells expressed CD45RO. The number of CD3⁺CD161⁺ T cells was significantly lower in the bronchoalveolar space than in the blood (4.6% of BACs vs 8.4% of peripheral blood mononuclear cells (PBMCs); P<0.05). We also found that 2.17% of CD4⁺ T lymphocytes and 1.52% of CD8⁺ T lymphocytes expressed CD161. Twenty-two percent of the alveolar CD3⁺CD161⁺ T lymphocytes produced cytokines upon stimulation by PMA plus ionomycin, and significantly more interferon gamma (IFN-γ) was produced compared with other cytokines (P = 0.05). Most alveolar CD3⁺CD161⁺ T cells produced interleukin-17 (IL-17) and IFN-γ simultaneously, and the percentage of these cells was significantly higher than the percentage of CD3⁺CD161⁻ T cells. Moreover, the percentage of alveolar CD3⁺CD161⁺ T lymphocytes that produced IFN-γ/IL-17 was significantly higher than those in the peripheral blood (p<0.05). In conclusion, Th1/Th17-CD3⁺CD161⁺ T_RM could contribute to compartment-specific immune responses in the lung.

Complexity and Diversity of the NKR-P1:Clr (Klrb1:Clec2) Recognition Systems

The NKR-P1 receptors were identified as prototypical natural killer (NK) cell surface antigens and later shown to be conserved from rodents to humans on NK cells and subsets of T cells. C-type lectin-like in nature, they were originally shown to be capable of activating NK cell function and to recognize ligands on tumor cells. However, certain family members have subsequently been shown to be capable of inhibiting NK cell activity, and to recognize proteins encoded by a family of genetically linked C-type lectin-related ligands. Some of these ligands are expressed by normal, healthy cells, and modulated during transformation, infection, and cellular stress, while other ligands are upregulated during the immune response and during pathological circumstances. Here, we discuss historical and recent developments in NKR-P1 biology that demonstrate this NK receptor–ligand system to be far more complex and diverse than originally anticipated.

Alloimmune activation promotes anti-cancer cytotoxicity after rat liver transplantation

Liver transplantation for hepatocellular carcinoma (HCC) results in a specific condition where the immune response is potentially directed against both allogeneic and cancer antigens. We have investigated the level of anti-cancer immunity during allogeneic immune response. Dark Agouti-to-Lewis and Lewis-to-Lewis rat liver transplantations were performed and the recipients anti-cancer immunity was analysed at the time of alloimmune activation. The occurrence of rejection in the allogeneic recipients was confirmed by a shorter survival (p<0.01), increased liver function tests (p<0.01), the presence of signs of rejection on histology, and a donor-specific ex vivo mixed lymphocyte reaction. At the time of alloimmune activation, blood mononuclear cells of the allogeneic group demonstrated increased anti-cancer cytotoxicity (p<0.005), which was related to an increased natural killer (NK) cell frequency (p<0.05) and a higher monocyte/macrophage activation level (p<0.01). Similarly, liver NK cell anti-cancer cytotoxicity (p<0.005), and liver monocyte/macrophage activation levels (p<0.01) were also increased. The alloimmune-associated cytotoxicity was mediated through the NKG2D receptor, whose expression was increased in the rejected graft (p<0.05) and on NK cells and monocyte/macrophages. NKG2D ligands were expressed on rat HCC cells, and its inhibition prevented the alloimmune-associated cytotoxicity. Although waiting for in vivo validation, alloimmune-associated cytotoxicity after rat liver transplantation appears to be linked to increased frequencies and levels of activation of NK cells and monocyte/macrophages, and is at least in part mediated through the NKG2D receptor.

Combined ChIP-Seq and transcriptome analysis identifies AP-1/JunD as a primary regulator of oxidative stress and IL-1β synthesis in macrophages

BACKGROUND

The oxidative burst is one of the major antimicrobial mechanisms adopted by macrophages. The WKY rat strain is uniquely susceptible to experimentally induced macrophage-dependent crescentic glomerulonephritis (Crgn). We previously identified the AP-1 transcription factor JunD as a determinant of macrophage activation in WKY bone marrow-derived macrophages (BMDMs). JunD is over-expressed in WKY BMDMs and its silencing reduces Fc receptor-mediated oxidative burst in these cells.

RESULTS

Here we combined Jund RNA interference with microarray analyses alongside ChIP-sequencing (ChIP-Seq) analyses in WKY BMDMs to investigate JunD-mediated control of macrophage activation in basal and lipopolysaccharide (LPS) stimulated cells. Microarray analysis following Jund silencing showed that Jund activates and represses gene expression with marked differential expression (>3 fold) for genes linked with oxidative stress and IL-1β expression. These results were complemented by comparing whole genome expression in WKY BMDMs with Jund congenic strain (WKY.LCrgn2) BMDMs which express lower levels of JunD. ChIP-Seq analyses demonstrated that the increased expression of JunD resulted in an increased number of binding events in WKY BMDMs compared to WKY.LCrgn2 BMDMs. Combined ChIP-Seq and microarray analysis revealed a set of primary JunD-targets through which JunD exerts its effect on oxidative stress and IL-1β synthesis in basal and LPS-stimulated macrophages.

CONCLUSIONS

These findings demonstrate how genetically determined levels of a transcription factor affect its binding sites in primary cells and identify JunD as a key regulator of oxidative stress and IL-1β synthesis in primary macrophages, which may play a role in susceptibility to Crgn.

Novel method for isolating untouched rat natural killer cells with higher purity compared with positive selection and fluorescence-activated cell sorting

Natural killer (NK) cells are important effectors of both innate and adaptive immune responses. Although human and mouse NK cells are extensively characterized, much less is known about the rat cells, partly because of the current lack of reliable isolation techniques. We aimed to develop a method for isolating highly pure 'untouched' rat NK cells by negative selection from splenocytes. Thereafter, we characterized them phenotypically and functionally in comparison with those isolated by positive selection targeting the NKR-P1 receptor. Our novel method isolated highly pure untouched NK cells reproducibly with 97 ± 0.7% (n = 7), 96.6 ± 0.8% (n = 3) and 88.3 ± 1.5% (n = 9) in LEWIS, Fischer and athymic nude rats, respectively. The positively selected NK cells were less homogeneous and exhibited undesired method-related activation profiles. Resting negatively selected NK cells were less proliferative and less robust compared with positively selected NK cells. Although resting positively selected NK cells were more cytotoxic, interleukin-2 (IL-2) activation increased the cytotoxicity of negatively selected cells three-fold. The negatively selected NK cells responded to cross-linking of the NKR-P1 receptor by calcium mobilization from intracellular stores. However, combined IL-2 and IL-12 activation resulted in significantly more interferon-γ release from positively selected NK cells. This new NK-cell isolation method will allow a deeper insight into rat NK-cell phenotypes and the roles of their receptors in the biology of these cells.

C-type lectins, fungi and Th17 responses

Th17 cells are a recently discovered subset of T helper cells characterised by the release of IL-17, and are thought to be important for mobilization of immune responses against microbial pathogens, but which also contribute to the development of autoimmune diseases. The identification of C-type lectin receptors which are capable of regulating the balance between Th1 and Th17 responses has been of particular recent interest, which they control, in part, though the release of Th17 inducing cytokines. Many of these receptors recognise fungi, and other pathogens, and play key roles in driving the development of protective anti-microbial immunity. Here we will review the C-type lectins that have been linked to Th17 type responses and will briefly examine the role of Th17 responses in murine and human anti-fungal immunity.

PILAR is a novel modulator of human T-cell expansion

Robust T-cell responses without autoimmunity are only possible through a fine balance between activating and inhibitory signals. We have identified a novel modulator of T-cell expansion named proliferation-induced lymphocyte-associated receptor (PILAR). Surface PILAR is markedly up-regulated on CD4 and, to a lesser extent, on CD8 T cells on T-cell receptor engagement. In absence of CD28 costimulation, PILAR signaling through CD161 supports CD3 antibody-dependent and antigen-specificT-cell proliferation by increasing the expression of antiapoptotic Bcl-xL and induces secretion of T helper type 1 cytokines. These effects are abrogated by PILAR blockade with specific antibodies, which decrease surface levels of CD28. In contrast, PILAR induces apoptotic death on naive and early activated T cells if CD161 engagement is blocked. PILAR is expressed by approximately 7% to 10% of CD4 T cells in 2 samples of inflammatory synovial fluid, suggesting a potential role in the pathogenesis of joint inflammation. In addition, in the ovarian cancer microenvironment, effector T cells express PILAR, but not CD161, although expression of both can be augmented ex vivo. Our results indicate that PILAR plays a central role in modulating the extent of T-cell expansion. Manipulation of PILAR signaling may be important for treatment of autoimmune diseases and cancer.

Dendritic cell subsets in lymph nodes are characterized by the specific draining area and influence the phenotype and fate of primed T cells

Dendritic cells (DC) are important in differential T-cell priming. Little is known about the local priming by DC in the microenvironment of different lymph nodes and about the fate of the imprinted T cells. Therefore, freshly isolated rat DC from mesenteric lymph nodes (mLN) and axillary lymph nodes (axLN) were phenotyped and cultured with blood T cells in the presence of the superantigen Mycoplasma arthritidis mitogen (MAM). The phenotype, proliferation and apoptosis of the primed T cells were analysed. Our data show that a common DC population exists in both mLN and axLN. In addition, region-specific DC with an organotypical marker expression imprinted by the drained area were found. Coculture of T cells with DC from mLN or axLN resulted in a distinct shift in the CD4 and CD8 expression of T cells and their phenotype. Furthermore, when these differentially primed mLN and axLN T cells were injected into recipients, mLN-primed T cells survived longer in other lymphoid organs. The results show that the region-specific DC have a unique phenotype and an impact on the ratio of CD4 : CD8 T cells during an immune response in vivo.

Increased Frequency of CD4+ Cells Expressing CD161 in Cancer Patients

PURPOSE

Although the function of natural killer receptors on T cells infiltrating tumors and their potential effect on antitumor immunity has been investigated, little is known about T cells expressing NKR-P1A (CD161) in cancer patients. In the present study, we examined T cells expressing CD161 in the peripheral blood, the tumor tissue and in malignant effusions of patients with several types of malignancies.

EXPERIMENTAL DESIGN

Expression of CD161 in CD4(+) or CD8(+) (lacking CD56) T cells isolated from peripheral blood (n = 61), tumor specimens (n = 8), and malignant effusions (n = 37) of cancer patients was examined using four-color flow cytometry. Proliferative capacity and cytokine production of purified CD4(+)CD161(+)CD56(-) cells were studied after weak or strong stimulation, with or without costimulation, in the presence or absence of interleukin 2. The possible regulatory function of activated CD4(+)CD161(+)CD56(-) cells on T-cell alloresponses was also investigated.

RESULTS

CD4(+) cells expressing CD161 were increased in cancer patients, compared with healthy individuals. This increase in the peripheral blood of cancer patients positively correlated with disease stage and was augmented at the tumor site. Phenotypic analysis revealed that CD4(+)CD161(+) cells are memory T cells, with low expression of activation markers. CD4(+)CD161(+) cells play an immunoregulatory role through cytokine production, because upon receiving costimulatory signals via CD28, they exert suppressive activity on autologous peripheral blood mononuclear cell alloresponses.

CONCLUSIONS

CD4(+)CD161(+)CD56(-) cells represent a distinct memory T-cell population significantly increased in cancer patients. Depending on the type of signals provided by the tumor microenvironment, CD4(+)CD161(+) cells may regulate the immune response.

Recognition of a carbohydrate xenoepitope by human NKRP1A (CD161)

BACKGROUND

Many immunologically important interactions are mediated by leukocyte recognition of carbohydrates via cell surface receptors. Uncharacterized receptors on human natural killer (NK) cells interact with ligands containing the terminal Galalpha(1,3)Gal xenoepitope. The aim of this work was to isolate and characterize carbohydrate binding proteins from NK cells that bind alphaGal or other potential xenoepitopes, such as N-acetyllactosamine (NAcLac), created by the deletion of alpha1,3galactosyltransferase (GT) in animals.

METHODS AND RESULTS

Initial analysis suggested the human C-type lectin NKRP1A bound to a pool of glycoconjugates, the majority of which contained the terminal Galalpha(1,3)Gal epitope. This was confirmed by high level binding of cells expressing NKRP1A to mouse laminin, which contains a large number of N-linked oligosaccharides with the Galalpha(1,3)Gal structure. The consequence of removing the terminal alphaGal was then investigated. Elevated NAcLac levels were observed on thymocytes from GT-/- mice. Exposing NAcLac on laminin, by alpha-galactosidase treatment, resulted in a significant increase in NKRP1A binding.

CONCLUSIONS

NKRPIA binds to the alphaGal epitope. Moreover, exposing NAcLac by removal of alphaGal resulted in an increase in binding. This may be relevant in the later phases of xenotransplant rejection if GT-/- pigs, like GT-/- mice, display increased NAcLac expression.

Expression of CD161 (NKR-P1A) defines subsets of human CD4 and CD8 T cells with different functional activities

A subset of T cells in human peripheral blood expresses CD161 (NKR-P1A) receptors that are primarily associated with NK cells. In the current study we isolated blood T cell subsets according to the expression of CD161 and examined their contents of naive, central memory, and effector memory cells and their capacities for proliferation, cytokine secretion, and natural cytolysis. We found that CD4+CD161- and CD8+CD161- subsets contained predominantly naive T cells that secreted high levels of IL-2 after in vitro stimulation, and CD4+CD161int and CD8+CD161int subsets contained predominantly effector and central memory T cells that secreted high levels of IFN-gamma and TNF-alpha. All of these subsets showed vigorous proliferation after stimulation in vitro, but none had NK lytic activity. Unexpectedly, the CD8+CD161+ cells contained an anergic CD8alpha+CD8betalow/-CD161high T cell subset that failed to proliferate, secrete cytokines, or mediate NK lytic activity.

Divergence of natural killer cell receptor and related molecule in the decidua from sporadic miscarriage with normal chromosome karyotype

The aim of this cohort study was to investigate immunophenotypic characteristics of natural killer (NK) cells by assessing specific molecules expressed in the decidua of sporadic miscarriages and induced abortions. The deciduae were obtained from 29 consecutively seen women whose pregnancies ended in first trimester miscarriages (MS), and the fetal chromosome karyotype of these MS was analysed. Additionally, 13 deciduae were obtained from induced abortion (IA) with informed consent. The expression of perforin, CD94, CD161, CD158a, CD158b, CD244 on CD3-CD56+NK cells, and perforin on CD3+CD8+ T cells was analysed by flow cytometry. The CD158a (mean+/-SD, 26.2+/-14.7%) and CD94 (50.2+/-25.7%) expressions in MS with normal chromosome karyotype (MSNK; n=11) were significantly decreased as compared with those (41.5+/-19.5%, 71.4+/-20.4%) in MS with abnormal karyotype (MSAK; n=18) and those (44.3+/-21.9%, 80.8+/-17.5%) in IA (n=13). Conversely, the perforin expression on CD3-CD8-CD56+NK cells (76.3+/-11.0%) and CD3+CD8+T cells (30.6+/-9.2%) in MSNK was significantly increased as compared with those (66.8+/-16.6%, 23.6+/-8.7%) in MSAK and those (62.9+/-11.6%, 19.7+/-8.1%) in IA. A positive correlation between CD94 and CD158a expressions on NK cells, negative correlations between CD94 on NK cells and perforin on NK cells/T cells, and between CD158a on NK cells and perforin on T cells were found in the decidua. A divergence of NK cell repertoire in the decidua might be related to aetiology of sporadic MSNK.

Functional requirements for signaling through the stimulatory and inhibitory mouse NKR-P1 (CD161) NK cell receptors

The NK cell receptor protein 1 (NKR-P1) (CD161) molecules represent a family of type II transmembrane C-type lectin-like receptors expressed predominantly by NK cells. Despite sharing a common NK1.1 epitope, the mouse NKR-P1B and NKR-P1C receptors possess opposing functions in NK cell signaling. Engagement of NKR-P1C stimulates cytotoxicity of target cells, Ca2+ flux, phosphatidylinositol turnover, kinase activity, and cytokine production. In contrast, NKR-P1B engagement inhibits NK cell cytotoxicity. Nonetheless, it remains unclear how different signaling outcomes are mediated at the molecular level. Here, we demonstrate that both NKR-P1B and NKR-P1C associate with the tyrosine kinase, p56(lck). The interaction is mediated through the di-cysteine CxCP motif in the cytoplasmic domains of NKR-P1B/C. Disrupting this motif leads to abrogation of both stimulatory and inhibitory NKR-P1 signals. In addition, mutation of the consensus ITIM (LxYxxL) in NKR-P1B abolishes both its Src homology 2-containing protein tyrosine phosphatase-1 recruitment and inhibitory function. Strikingly, engagement of NKR-P1C on NK cells obtained from Lck-deficient mice failed to induce NK cytotoxicity. These results reveal a role for Lck in the initiation of NKR-P1 signals, and demonstrate a requirement for the ITIM in NKR-P1-mediated inhibition.

Decrease in a specific killer cell immunoglobulin-like receptor on peripheral natural killer cells in women with recurrent spontaneous abortion of unexplained etiology

PROBLEM

The aim of this study was to investigate immunophenotypic characteristics of natural killer (NK) cells by assessing specific molecules expressed in women with recurrent spontaneous abortion (RSA) of unexplained etiology.

METHOD OF STUDY

Peripheral blood cells were obtained from 20 RSA women and 15 fertile controls. The expression of perforin, CD94, CD161, CD158a, CD158b, and CD244 on CD3- CD56+ NK cells was analyzed by flow cytometry.

RESULTS

A significant decrease in CD158a expression was demonstrated in RSA women (mean +/- SD, 22.9 +/- 8.7%) as compared with that in controls (33.6 +/- 15.7%) (P < 0.05). The percentage of NK cells showing dual expression of CD94 and CD161 was relatively higher in RSA women (55.1 +/- 10.2%) than in the controls (47.1 +/- 19.0%), but without statistically significant (P = 0.096). The expression of perforin, CD158b, or CD244 in RSA women did not differ from that in the controls.

CONCLUSIONS

A divergence of the specific NK cell repertoire might be related to the etiology of RSA.

Dendritic cells induce the death of human papillomavirus-transformed keratinocytes

Although human papillomavirus (HPV) antigens are expressed in a majority of (pre)neoplastic lesions (squamous intraepithelial lesions; SILs) of the uterine cervix, progression to invasive cancer may occur, which suggests that the presentation of viral antigens to the immune system is deficient in some SILs. To determine whether professional antigen-presenting cells die in SILs, we assayed for the apoptosis of immature dendritic cells (DC) in organotypic cultures of HPV-transformed keratinocytes, which reproduce many features of in vivo observed SILs. Unexpectedly, the infiltration of organotypic cultures by DC specifically induced the apoptosis of HPV+ tumor cells, whereas DC were not affected. In the same conditions and in coculture experiments, apoptosis was not observed in normal keratinocytes. The induction of apoptosis required membrane contacts between DC and HPV-transformed keratinocytes. Although the HPV+cell lines were sensitive to the effects of TRAIL, soluble TRAILR2-Fc did not block the DC-induced apoptosis. Furthermore, although FasL and Fas were detected on DC and HPV+ cell lines, respectively, functional analysis revealed that this pathway is not responsible for the apoptosis induced by the DC. All together these results suggest that DC may be at the interface between innate and adaptive immunity by inducing the apoptosis of (pre)neoplastic cells.

Divergent and convergent evolution of NK-cell receptors

Natural killer (NK)-cell receptors specific for major histocompatibility complex (MHC) class I molecules have been identified in humans and mice. Some of the most important receptors are structurally unrelated in the two species: the murine Ly-49 receptors are C-type lectins, while human killer-cell inhibitory receptors (KIRs) belong to the immunoglobulin superfamily. Here, Roland Barten and colleagues describe the divergent and convergent evolution of NK-cell receptors.

The role of dendritic cells in the innate immune system

Dendritic cells (DCs) are bone-marrow-derived leucocytes that are specialised antigen-presenting cells capable of stimulating a primary T-lymphocyte response to specific antigen. In this chapter we discuss the role DCs play in the innate response acting as a critical link with the adaptive response and the influence of the innate response on dendritic cells.

Langerin, a novel C-type lectin specific to Langerhans cells, is an endocytic receptor that induces the formation of Birbeck granules

We have identified a type II Ca2+-dependent lectin displaying mannose-binding specificity, exclusively expressed by Langerhans cells (LC), and named Langerin. LC are uniquely characterized by Birbeck granules (BG), which are organelles consisting of superimposed and zippered membranes. Here, we have shown that Langerin is constitutively associated with BG and that antibody to Langerin is internalized into these structures. Remarkably, transfection of Langerin cDNA into fibroblasts created a compact network of membrane structures with typical features of BG. Langerin is thus a potent inducer of membrane superimposition and zippering leading to BG formation. Our data suggest that induction of BG is a consequence of the antigen-capture function of Langerin, allowing routing into these organelles and providing access to a nonclassical antigen-processing pathway.

Effects of alpha-galactosylceramide (KRN7000), interleukin-12 and interleukin-7 on phenotype and cytokine profile of human Valpha24+ Vbeta11+ T cells

The alpha-galactosylceramide KRN7000 was reported to be presented by CD1d to natural killer (NK) T cells, cells that are thought to play an important role in the rejection of malignant tumours and in the regulation of several autoimmune diseases. Here we analysed human peripheral blood (PB) NK T cells (Valpha24+ Vbeta11+ T cells) before and after a short-term culture in the presence of KRN7000. KRN7000 strongly activated PB Valpha24+ Vbeta11+ T cells and, when stimulated, the vast majority of these cells expressed interferon-gamma (IFN-gamma). Exposure of these KRN7000-cultured Valpha24+ Vbeta11+ T cells to interleukin-12 (IL-12), but not to IL-7, resulted in a relative increase in IFN-gamma-expressing Valpha24+ Vbeta11+ T cells, compared with IL-4-expressing Valpha24+ Vbeta11+ T cells, indicating a shift towards a T-helper type 1 (Th1) phenotype. KRN7000 strongly up-regulated the expression of the cytotoxic molecule granzyme B (GrB) in Valpha24+ Vbeta11+ T cells. Although IL-7 resulted in a decrease in GrB levels in KRN7000-cultured Valpha24+ Vbeta11+ T cells, IL-12 increased GrB levels in both Valpha24+ Vbeta11+ T cells and in Valpha24+ Vbeta11+ T-cell clones and increased cytotoxicity against hCD1d-transfected HeLa cells. Our data provide further insight into the characteristics of human Valpha24+ Vbeta11+ T cells and indicate that KRN7000 is a potent activator of Valpha24+ Vbeta11+ T cells. Combined with the established anti-tumour effects of KRN7000 in mouse models, these results may support the use of KRN7000 as an anti-tumour agent in man.

Dendritic cells: a link between innate and adaptive immunity

Dendritic cells (DC) constitute a unique system of cells able to induce primary immune responses. As a component of the innate immune system, DC organize and transfer information from the outside world to the cells of the adaptive immune system. DC can induce such contrasting states as active immune responsiveness or immunological tolerance. Recent years have brought a wealth of information regarding DC biology and pathophysiology, that shows the complexity of this cell system. Although our understanding of DC biology is still in its infancy, we are now in a position to use DC-based immunotherapy protocols to treat cancer and infectious diseases.

Augmentation of natural killer cell activity in mice by oral administration of transforming growth factor-beta

The latent form of transforming growth factor-beta (TGF-beta) in human milk and platelets was converted to the active form when conscious, pylorus-ligated mice were given human milk and platelets by intragastric intubation. Oral administration of TGF-beta exerted enhancing effects on the natural killer (NK)-cell activities in spleen and liver. Augmentation of NK-cell activities in spleen was observed for 7 days after oral administration of TGF-beta. TGF-beta at concentrations of 5 and 20 ng produced the greatest augmentation of NK-cell activities in spleen. However, NK-cell activities in spleen were unaffected when TGF-beta was given intravenously. Interleukin (IL)-12 production in spleen was enhanced by oral administration of TGF-beta, but not by intravenous administration of TGF-beta. These findings suggest that large amounts of TGF-beta in human milk are involved in early antiviral protection through the augmentation of NK-cell activities.

Differential Transcriptional Regulation of CD161 and a Novel Gene, 197/15a, by IL-2, IL-15, and IL-12 in NK and T Cells

Cytokine-mediated enhancement of spontaneous cytotoxicity depends, at least in part, on modulation of the expression of surface molecules responsible for recognition of target cell structures and triggering or inhibition of the cytotoxic machinery. We previously demonstrated that expression of transcription factors (e.g., Egr-1, JunB, and c-Fos) is differentially regulated by IL-2 and IL-12. Here we show that expression of CD161/NKR-P1A, a molecule involved in triggering cytotoxicity, is specifically up-regulated by IL-12. CD161 transcription, mRNA accumulation, and surface expression are increased by IL-12. Other cytokines sharing the IL-2R β- and/or common γ-chains (i.e., IL-15, IL-4, and IL-7) do not mediate these effects. In an effort to analyze the mechanisms by which IL-2, IL-12, and IL-15 differentially regulate gene transcription, we have isolated a novel gene, 197/15a, the expression of which in NK and T cells is down-regulated by IL-2 and IL-15, up-regulated by IL-12, and not affected by IL-4 and IL-7. IL-2 and IL-15 act, at least in part, repressing 197/15a transcription; their effect on 197/15a mRNA accumulation is partially independent of novel protein synthesis, likely not mediated by JunB, Bcl-2, or Bax, and requires the activity of rapamycin-sensitive molecule(s). The observation that IL-2 and IL-12 differentially modulate CD161 expression suggests the existence of cytokine-specific mechanisms of modulation of spontaneous cytotoxicity based on the regulation of expression of surface molecules involved in target cell recognition and/or triggering of the cytolytic machinery.

Lineage commitment and differentiation of T and natural killer lymphocytes in the fetal mouse

T cells and natural killer (NK) cells are presumed to share a common intrathymic precursor. The development of conventional alpha beta T lymphocytes begins within the early fetal thymus, after the colonization of multipotent CD117+ precursors. Irrevocable commitment to the T lineage is marked by thymus-induced expression of CD25. However, the contribution of the fetal thymus to NK lineage commitment and differentiation remains largely unappreciated. Recently, we demonstrated that the development of functional mouse NK cells occurs first in the fetal thymus. Moreover, the appearance of mature fetal thymic NK cells (NK1.1+/CD117-) is preceded by a thymus-induced developmental stage (NK1.1+/CD117+) that marks lineage commitment of multipotent hematopoietic precursors to the T and NK-cell fates. Commitment to the T/NK bipotent stage is induced by fetal thymic stroma, but is not thymus dependent. Recent data indicate that CD90+/CD117lo fetal blood prothymocytes exhibit NK lineage potential and are phenotypically and functionally identical to fetal thymic NK1.1+/CD117+ progenitors. This finding also indicates that full commitment of circulating precursors to the T-cell lineage occurs after thymus colonization. In this review, we discuss recent insights into the cellular and molecular events involved in fetal mouse T and NK lineage commitment and differentiation to unipotent progenitors.

CD161 (NKR-P1A) costimulation of CD1d-dependent activation of human T cells expressing invariant V alpha 24 J alpha Q T cell receptor alpha chains

A population of human T cells expressing an invariant V alpha 24 J alpha Q T cell antigen receptor (TCR) alpha chain and high levels of CD161 (NKR-P1A) appears to play an immunoregulatory role through production of both T helper (Th) type 1 and Th2 cytokines. Unlike other CD161(+) T cells, the major histocompatibility complex-like nonpolymorphic CD1d molecule is the target for the TCR expressed by these T cells (V alpha 24(invt) T cells) and by the homologous murine NK1 (NKR-P1C)+ T cell population. In this report, CD161 was shown to act as a specific costimulatory molecule for TCR-mediated proliferation and cytokine secretion by V alpha 24(invt) T cells. However, in contrast to results in the mouse, ligation of CD161 in the absence of TCR stimulation did not result in V alpha 24(invt) T cell activation, and costimulation through CD161 did not cause polarization of the cytokine secretion pattern. CD161 monoclonal antibodies specifically inhibited V alpha 24(invt) T cell proliferation and cytokine secretion in response to CD1d+ target cells, demonstrating a physiological accessory molecule function for CD161. However, CD1d-restricted target cell lysis by activated V alpha 24(invt) T cells, which involved a granule-mediated exocytotic mechanism, was CD161-independent. In further contrast to the mouse, the signaling pathway involved in V alpha 24(invt) T cell costimulation through CD161 did not appear to involve stable association with tyrosine kinase p56(Lck). These results demonstrate a role for CD161 as a novel costimulatory molecule for TCR-mediated recognition of CD1d by human V alpha 24(invt) T cells.

Involvement of dihydropyridine-sensitive calcium channels in human dendritic cell function. Competition by HIV-1 Tat

The entry of extracellular calcium in leukocytes mediates several cellular processes; however, unlike in excitable tissues, the underlying molecular mechanisms are poorly defined. In this paper we provide phenotypical and biochemical evidence that peripheral blood-derived human dendritic cells express dihydropyridine-sensitive calcium channels. Exposure to the dihydropyridine drug nifedipine, which binds L-type calcium channels blocking calcium influx, prevents two dendritic cell functions that are dependent on extracellular calcium entry: apoptotic body engulfment and interleukin-12 production induced by cross-linking of the surface lectin NKRP1A. It is known that exogenous human immunodeficiency virus, type 1 Tat affects several Ca2+-dependent immune cell responses. Here we demonstrate that Tat inhibits apoptotic body engulfment and interleukin-12 production by blocking extracellular calcium influx. This inhibition is prevented by the calcium channel agonist dihydropyridine derivative Bay K 8644, suggesting the involvement of L-type calcium channels. This hypothesis is further supported by the observation that Tat and dihydropyridine drugs compete for binding to dendritic cells. Taken together, these findings indicate that exogenous Tat exerts its inhibitory effects on dendritic cells by blocking dihydropyridine-sensitive L-type calcium channels.