Human NK Cells Lyse Th2-Polarizing Dendritic Cells via NKp30 and DNAM-1

Exploring the molecular mechanisms of asthma across multiple datasets

BACKGROUND

Asthma, a prevalent chronic respiratory disorder, remains enigmatic, notwithstanding considerable advancements in our comprehension. Continuous efforts are crucial for discovering novel molecular targets and gaining a comprehensive understanding of its pathogenesis.

MATERIALS AND METHODS

In this study, we analyzed gene expression data from 212 individuals, including asthma patients and healthy controls, to identify 267 differentially expressed genes, among which C1orf64 and C7orf26 emerged as potential key genes in asthma pathogenesis. Various bioinformatics tools, including differential gene expression analysis, pathway enrichment, drug target prediction, and single-cell analysis, were employed to explore the potential roles of the genes.

RESULTS

Quantitative PCR demonstrated differential expression of C1orf64 and C7orf26 in the asthmatic airway epithelial tissue, implying their potential involvement in asthma pathogenesis. GSEA enrichment analysis revealed significant enrichment of these genes in signaling pathways associated with asthma progression, such as ABC transporters, cell cycle, CAMs, DNA replication, and the Notch signaling pathway. Drug target prediction, based on upregulated and downregulated differential expression, highlighted potential asthma treatments, including Tyrphostin-AG-126, Cephalin, Verrucarin-a, and Emetine. The selection of these drugs was based on their significance in the analysis and their established anti-inflammatory and antiviral invasion properties. Utilizing Seurat and Celldex packages for single-cell sequencing analysis unveiled disease-specific gene expression patterns and cell types. Expression of C1orf64 and C7orf26 in T cells, NK cells, and B cells, instrumental in promoting hallmark features of asthma, was observed, suggesting their potential influence on asthma development and progression.

CONCLUSION

This study uncovers novel genetic aspects of asthma, highlighting potential therapeutic pathways. It exemplifies the power of integrative bioinformatics in decoding complex disease patterns. However, these findings require further validation, and the precise roles of C1orf64 and C7orf26 in asthma warrant additional investigation to validate their therapeutic potential.

Progressive accumulation of hyperinflammatory NKG2Dlow NK cells in early childhood severe atopic dermatitis

Atopic dermatitis (AD) is a chronic inflammatory skin disease that often precedes the development of food allergy, asthma, and allergic rhinitis. The prevailing paradigm holds that a reduced frequency and function of natural killer (NK) cell contributes to AD pathogenesis, yet the underlying mechanisms and contributions of NK cells to allergic comorbidities remain ill-defined. Here, analysis of circulating NK cells in a longitudinal early life cohort of children with AD revealed a progressive accumulation of NK cells with low expression of the activating receptor NKG2D, which was linked to more severe AD and sensitivity to allergens. This was most notable in children co-sensitized to food and aeroallergens, a risk factor for development of asthma. Individual-level longitudinal analysis in a subset of children revealed coincident reduction of NKG2D on NK cells with acquired or persistent sensitization, and this was associated with impaired skin barrier function assessed by transepidermal water loss. Low expression of NKG2D on NK cells was paradoxically associated with depressed cytolytic function but exaggerated release of the proinflammatory cytokine tumor necrosis factor-α. These observations provide important insights into a potential mechanism underlying the development of allergic comorbidity in early life in children with AD, which involves altered NK cell functional responses, and define an endotype of severe AD.

Natural killer cells in the lung: potential role in asthma and virus-induced exacerbation?

Asthma is a chronic inflammatory airway disorder whose pathophysiological and immunological mechanisms are not completely understood. Asthma exacerbations are mostly driven by respiratory viral infections and characterised by worsening of symptoms. Despite current therapies, asthma exacerbations can still be life-threatening. Natural killer (NK) cells are innate lymphoid cells well known for their antiviral activity and are present in the lung as circulating and resident cells. However, their functions in asthma and its exacerbations are still unclear. In this review, we will address NK cell activation and functions, which are particularly relevant for asthma and virus-induced asthma exacerbations. Then, the role of NK cells in the lungs at homeostasis in healthy individuals will be described, as well as their functions during pulmonary viral infections, with an emphasis on those associated with asthma exacerbations. Finally, we will discuss the involvement of NK cells in asthma and virus-induced exacerbations and examine the effect of asthma treatments on NK cells.

Progressive accumulation of hyperinflammatory NKG2D low NK cells in early childhood severe atopic dermatitis

Atopic dermatitis (AD) is a chronic inflammatory skin disease that often precedes the development of food allergy, asthma, and allergic rhinitis. The prevailing paradigm holds that a reduced frequency and function of natural killer (NK) cell contributes to AD pathogenesis, yet the underlying mechanisms and contributions of NK cells to allergic co-morbidities remain ill-defined. Herein, analysis of circulating NK cells in a longitudinal early life cohort of children with AD revealed a progressive accumulation of NK cells with low expression of the activating receptor NKG2D, which was linked to more severe AD and sensitivity to allergens. This was most notable in children co-sensitized to food and aero allergens, a risk factor for development of asthma. Individual-level longitudinal analysis in a subset of children revealed co-incident reduction of NKG2D on NK cells with acquired or persistent sensitization, and this was associated with impaired skin barrier function assessed by transepidermal water loss. Low expression of NKG2D on NK cells was paradoxically associated with depressed cytolytic function but exaggerated release of the proinflammatory cytokine TNF-α. These observations provide important insights into a potential mechanism underlying the development of allergic co-morbidity in early life in children with AD which involves altered NK-cell functional responses, and define an endotype of severe AD.

Circulating CXCR5+ natural killer cells are expanded in patients with myasthenia gravis

Objectives

Myasthenia gravis (MG) is a classic autoantibody-mediated disease in which pathogenic antibodies target postsynaptic membrane components, causing fluctuating skeletal muscle weakness and fatigue. Natural killer (NK) cells are heterogeneous lymphocytes that have gained increasing attention owing to their potential roles in autoimmune disorders. This study will investigate the relationship between the distinct NK cell subsets and MG pathogenesis.

Methods

A total of 33 MG patients and 19 healthy controls were enrolled in the present study. Circulating NK cells, their subtypes and follicular helper T cells were analysed by flow cytometry. Serum acetylcholine receptor (AChR) antibody levels were determined by ELISA. The role of NK cells in the regulation of B cells was verified using a co-culture assay.

Results

Myasthenia gravis patients with acute exacerbations had a reduced number of total NK cells, CD56^dim NK cells and IFN-γ-secreting NK cells in the peripheral blood, while CXCR5⁺ NK cells were significantly elevated. CXCR5⁺ NK cells expressed a higher level of ICOS and PD-1 and a lower level of IFN-γ than those in CXCR5^- NK cells and were positively correlated with Tfh cell and AChR antibody levels. In vitro experiments demonstrated that NK cells suppressed plasmablast differentiation while promoting CD80 and PD-L1 expression on B cells in an IFN-γ-dependent manner. Furthermore, CXCR5^- NK cells inhibited plasmablast differentiation, while CXCR5⁺ NK cells could more efficiently promote B cell proliferation.

Conclusion

These results reveal that CXCR5⁺ NK cells exhibit distinct phenotypes and functions compared with CXCR5^- NK cells and might participate in the pathogenesis of MG.

The CD56-CD16+ NK cell subset in chronic infections

Long-term human diseases can shape the immune system, and natural killer (NK) cells have been documented to differentiate into distinct subsets specifically associated with chronic virus infections. One of these subsets found in large frequencies in HIV-1 are the CD56-CD16+ NK cells, and this population's association with chronic virus infections is the subject of this review. Human NK cells are classically defined by CD56 expression, yet increasing evidence supports the NK cell status of the CD56-CD16+ subset which we discuss herein. We then discuss the evidence linking CD56-CD16+ NK cells to chronic virus infections, and the potential immunological pathways that are altered by long-term infection that could be inducing the population's differentiation. An important aspect of NK cell regulation is their interaction with human leukocyte antigen (HLA) class-I molecules, and we highlight work that indicates both virus and genetic-mediated variations in HLA expression that have been linked to CD56-CD16+ NK cell frequencies. Finally, we offer a perspective on CD56-CD16+ NK cell function, taking into account recent work that implies the subset is comparable to CD56+CD16+ NK cell functionality in antibody-dependent cell cytotoxicity response, and the definition of CD56-CD16+ NK cell subpopulations with varying degranulation capacity against target cells.

Dendritic cell-natural killer cell cross-talk modulates T cell activation in response to influenza A viral infection

Influenza viruses lead to substantial morbidity and mortality including ~3-5 million cases of severe illness and ~290,000-650,000 deaths annually. One of the major hurdles regarding influenza vaccine efficacy is generating a durable, robust cellular immune response. Appropriate stimulation of the innate immune system is key to generating cellular immunity. Cross-talk between innate dendritic cells (DC) and natural killer (NK) cells plays a key role in activating virus-specific T cells, yet the mechanisms used by influenza A viruses (IAV) to govern this process remain incompletely understood. Here, we used an ex vivo autologous human primary immune cell culture system to evaluate the impact of DC-NK cell cross-talk and subsequent naïve T cell activation at steady-state and after exposure to genetically distinct IAV strains-A/California/07/2009 (H1N1) and A/Victoria/361/2011 (H3N2). Using flow cytometry, we found that exposure of DCs to IAV in co-culture with NK cells led to a decreased frequency of CD83⁺ and CD86⁺ cells on DCs and an increased frequency of HLA-DR⁺ on both DCs and NK cells. We then assessed the outcome of DC-NK cell cross-talk on T cell activation. At steady-state, DC-NK cell cross-talk increased pan T cell CD69 and CD25 expression while exposure to either IAV strain reduced pan T cell CD25 expression and suppressed CD4⁺ and CD8⁺ T cell IFN-γ and TNF production, following chemical stimulation with PMA/Ionomycin. Moreover, exposure to A/Victoria/361/2011 elicited lower IFN-γ production by CD4⁺ and CD8⁺ T cells compared with A/California/07/2009. Overall, our results indicate a role for DC-NK cell cross-talk in T cell priming in the context of influenza infection, informing the immunological mechanisms that could be manipulated for the next generation of influenza vaccines or immunotherapeutics.

Differential IL-12 signaling induces human natural killer cell activating receptor-mediated ligand-specific expansion

IL-12 is an essential cytokine involved in the generation of memory or memory-like NK cells. Mouse cytomegalovirus infection triggers NK receptor-induced, ligand-specific IL-12-dependent NK cell expansion, yet specific IL-12 stimulation ex vivo leading to NK cell proliferation and expansion is not established. Here, we show that IL-12 alone can sustain human primary NK cell survival without providing IL-2 or IL-15 but was insufficient to promote human NK cell proliferation. IL-12 signaling analysis revealed STAT5 phosphorylation and weak mTOR activation, which was enhanced by activating NK receptor upregulation and crosslinking leading to STAT5-dependent, rapamycin-sensitive, or TGFβ-sensitive NK cell IL-12-dependent expansion, independently of IL-12 receptor upregulation. Prolonged IL-2 culture did not impair IL-12-dependent ligand-specific NK cell expansion. These findings demonstrate that activating NK receptor stimulation promotes differential IL-12 signaling, leading to human NK cell expansion, and suggest adopting strategies to provide IL-12 signaling in vivo for ligand-specific IL-2-primed NK cell-based therapies.

Emergence of the CD226 Axis in Cancer Immunotherapy

In recent years, a set of immune receptors that interact with members of the nectin/nectin-like (necl) family has garnered significant attention as possible points of manipulation in cancer. Central to this axis, CD226, TIGIT, and CD96 represent ligand (CD155)-competitive co-stimulatory/inhibitory receptors, analogous to the CTLA-4/B7/CD28 tripartite. The identification of PVRIG (CD112R) and CD112 has introduced complexity and enabled additional nodes of therapeutic intervention. By virtue of the clinical progression of TIGIT antagonists and emergence of novel CD96- and PVRIG-based approaches, our overall understanding of the ‘CD226 axis’ in cancer immunotherapy is starting to take shape. However, several questions remain regarding the unique characteristics of, and mechanistic interplay between, each receptor-ligand pair. This review provides an overview of the CD226 axis in the context of cancer, with a focus on the status of immunotherapeutic strategies (TIGIT, CD96, and PVRIG) and their underlying biology (i.e., cis/trans interactions). We also integrate our emerging knowledge of the immune populations involved, key considerations for Fc gamma (γ) receptor biology in therapeutic activity, and a snapshot of the rapidly evolving clinical landscape.

Update in TIGIT Immune-Checkpoint Role in Cancer

The in-depth characterization of cross-talk between tumor cells and T cells in solid and hematological malignancies will have to be considered to develop new therapeutical strategies concerning the reactivation and maintenance of patient-specific antitumor responses within the patient tumor microenvironment. Activation of immune cells depends on a delicate balance between activating and inhibitory signals mediated by different receptors. T cell immunoreceptor with immunoglobulin and ITIM domain (TIGIT) is an inhibitory receptor expressed by regulatory T cells (Tregs), activated T cells, and natural killer (NK) cells. TIGIT pathway regulates T cell-mediated tumor recognition in vivo and in vitro and represents an exciting target for checkpoint blockade immunotherapy. TIGIT blockade as monotherapy or in combination with other inhibitor receptors or drugs is emerging in clinical trials in patients with cancer. The purpose of this review is to update the role of TIGIT in cancer progression, looking at TIGIT pathways that are often upregulated in immune cells and at possible therapeutic strategies to avoid tumor aggressiveness, drug resistance, and treatment side effects. However, in the first part, we overviewed the role of immune checkpoints in immunoediting, the TIGIT structure and ligands, and summarized the key immune cells that express TIGIT.

Anti-JMH alloantibody in inherited JMH-negative patients leads to immunogenic destruction of JMH-positive RBCs

The clinical significance of the specific anti-John Milton Hagen (JMH) alloantibody in inherited JMH-negative patients remains unclear. During clinical blood transfusion, it is often classified as an anti-JMH autoantibody in acquired JMH-negative patients, which might further lead to the occurrence of haemolysis events. In this study, we found that the proportion of inherited JMH-negative people in the Guangzhou population was 0.41%, based on the study of 243 blood samples by flow cytometry. Gene sequencing analysis revealed two novel variants located in exon 11 (c.1348G>A, p.Ala449Thr) and exon 14 (c.1989G>T, p.Leu663Phe). Specific antigen presentation showed that JMH-positive RBCs (red blood cells) could be internalized by SEMA7A^-/- dendritic cells (DCs) and that SEMA7A^-/- DCs activated by the semaphorin 7a (Sema7a) protein or JMH-positive erythrocytes further induced activation of CD4⁺ T cells to secrete interferon (IFN)-γ. Transfusion of JMH-positive RBCs could lead to the production of the specific anti-JMH alloantibody in Sema7a knock-out (KO) C57 mice. After erythrocyte sensitization, complement C3 was specifically fixed, causing the destruction of JMH-positive erythrocytes. The anti-JMH alloantibody caused immunological destruction of JMH-positive erythrocytes and promoted the clearance of JMH-positive RBCs. We should be cautious when making conclusions about the clinical significance of the anti-JMH alloantibody.

Characterization and Manipulation of the Crosstalk Between Dendritic and Natural Killer Cells Within the Tumor Microenvironment

Cellular therapy has entered the daily clinical life with the approval of CAR T cell therapeutics and dendritic cell (DCs) vaccines in the US and the EU. In addition, numerous other adoptive cellular products, including natural killer (NK) cells, are currently evaluated in early phase I/ II clinical trials for the treatment of cancer patients. Despite these promising accomplishments, various challenges remain to be mastered in order to ensure sustained therapeutic success. These include the identification of strategies by which tumor cells escape the immune system or establish an immunosuppressive tumor microenvironment (TME). As part of the innate immune system, DCs and NK cells are both present within the TME of various tumor entities. While NK cells are well known for their intrinsic anti-tumor activity by their cytotoxicity capacities and the secretion of pro-inflammatory cytokines, the role of DCs within the TME is a double-edged sword as different DC subsets have been described with either tumor-promoting or -inhibiting characteristics. In this review, we will discuss recent findings on the interaction of DCs and NK cells under physiological conditions and within the TME. One focus is the crosstalk of various DC subsets with NK cells and their impact on the progression or inhibition of tumor growth. In addition, we will provide suggestions to overcome the immunosuppressive outcome of the interaction of DCs and NK cells within the TME.

Natural Killer-Dendritic Cell Interactions in Liver Cancer: Implications for Immunotherapy

Simple Summary

The reciprocal crosstalk between dendritic cells (DCs) and natural killer (NK) cells plays a pivotal role in regulating immune defense against viruses and tumors. The Th-cell polarizing ability, cytokine-producing capacity, chemokine expression, and migration of DCs are regulated by activated NK cells. Conversely, the effector functions including lysis and cytokine production, proliferation, and migration of NK cells are influenced by close interactions with activated DCs. In this review, we explore the impact of DC–NK cell crosstalk and its therapeutic potential in immune control of liver malignances.

Abstract

Natural killer (NK) and dendritic cells (DCs) are innate immune cells that play a crucial role in anti-tumor immunity. NK cells kill tumor cells through direct cytotoxicity and cytokine secretion. DCs are needed for the activation of adaptive immune responses against tumor cells. Both NK cells and DCs are subdivided in several subsets endowed with specialized effector functions. Crosstalk between NK cells and DCs leads to the reciprocal control of their activation and polarization of immune responses. In this review, we describe the role of NK cells and DCs in liver cancer, focusing on the mechanisms involved in their reciprocal control and activation. In this context, intrahepatic NK cells and DCs present unique immunological features, due to the constant exposure to non-self-circulating antigens. These interactions might play a fundamental role in the pathology of primary liver cancer, namely hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (ICC). Additionally, the implications of these immune changes are relevant from the perspective of improving the cancer immunotherapy strategies in HCC and ICC patients.

Impact of Polyvalent Mechanical Bacterial Lysate on lymphocyte number and activity in asthmatic children: a randomized controlled trial

BACKGROUND

Polyvalent Mechanical Bacterial Lysate (PMBL®) contains antigens of bacteria responsible for respiratory infections. PMBL® has been proven to reduce the number of respiratory infections, and in its use, immunological benefits have been seen in allergic patients. PMBL® activates both innate and specific immune responses. The lysate induces dendritic cells, T and B lymphocytes and IgA secretion, as well as the production of antibodies directed against administered bacterial antigens. Moreover, it increases the response against other bacteria and viruses. The immunologic mechanism of lysate's action is not yet clearly determined. The objective of this study was to assess the effect of PMBL® on T cells in children with allergic asthma.

METHODS

This study was a part of the EOLIA study. Herein, 49 children with allergic asthma and house dust mites allergy were included: 21 in PMBL® and 28 in the Placebo group, both, drug and placebo were administered sublingually. The tests were done at baseline and 12 weeks after the last tablet intake. The lymphocytes CD45+, lymphocytes T CD3+, CD3+CD25+, CD3+CD69+, Th CD3+CD4+, CD4+CD25+, CD4+CD25+ high, CD4+CD69+, Treg CD4+CD25+FOXP3, Tc CD3+CD8+, CD8+CD25+, CD8+CD69+, NK-like T CD3+CD16+CD56+ and NK cells CD3-CD16+CD56+ were described.

RESULTS

At baseline, no significant differences between groups relative to blood count cells were observed, except for eosinophils. After 12 weeks, we observed an increase of T lymphocytes count. In addition, CD4+CD25+FOXP3+, CD8+ and CD3-CD16+CD56+ and (insignificantly) Th count increased. However, CD69+ and CD25+ subset of CD3+ significantly decreased.

CONCLUSIONS

The EOLIA study demonstrated that PMBL® administration 10 days per month for 3 months changed the panel of T lymphocytes. Trial registration Clinical Trial Registration: This study was a part of the EOLIA (Efficacy Of mechanical bacterial Lysate In Allergic children), a clinical study NCT02541331. Frederic Durmont, MD Lallemand Pharma International AG. Date of registration 09/08/2013. URL of trial registry record: https://clinicaltrials.gov/ct2/show/study/NCT02541331.

Natural Killer Cells and Host Defense Against Human Rhinoviruses Is Partially Dependent on Type I IFN Signaling

Rhinovirus (RV), the causative agent of the common cold, causes only mild upper respiratory tract infections in healthy individuals, but can cause longer lasting and more severe pulmonary infections in people with chronic lung diseases and in the setting of immune suppression or immune deficiency. RV-infected lung structural cells release type I interferon (IFN-I), initiating the immune response, leading to protection against viruses in conjunction with migratory immune cells. However, IFN-I release is deficient in some people with asthma. Innate immune cells, such as natural killer (NK) cells, are proposed to play major roles in the control of viral infections, and may contribute to exacerbations of chronic lung diseases, such as asthma. In this study, we characterized the NK cell response to RV infection using an in vitro model of infection in healthy individuals, and determined the extent to which IFN-I signaling mediates this response. The results indicate that RV stimulation in vitro induces NK cell activation in healthy donors, leading to degranulation and the release of cytotoxic mediators and cytokines. IFN-I signaling was partly responsible for NK cell activation and functional responses to RV. Overall, our findings suggest the involvement of NK cells in the control of RV infection in healthy individuals. Further understanding of NK cell regulation may deepen our understanding of the mechanisms that contribute to susceptibility to RV infections in asthma and other chronic lung diseases.

Differentiation and adaptation of natural killer cells for anti-malarial immunity

Natural killer cells employ a diverse arsenal of effector mechanisms to target intracellular pathogens. Differentiation of natural killer (NK) cell activation pathways occurs along a continuum from reliance on innate pro-inflammatory cytokines and stress-induced host ligands through to interaction with signals derived from acquired immune responses. Importantly, the degree of functional differentiation of the NK cell lineage influences the magnitude and specificity of interactions with host cells infected with viruses, bacteria, fungi, and parasites. Individual humans possess a vast diversity of distinct NK cell clones, each with the capacity to vary along this functional differentiation pathway, which - when combined - results in unique individual responses to different infections. Here we summarize these NK cell differentiation events, review evidence for direct interaction of malaria-infected host cells with NK cells and assess how innate inflammatory signals induced by malaria parasite-associated molecular patterns influence the indirect activation and function of NK cells. Finally, we discuss evidence that anti-malarial immunity develops in parallel with advancing NK differentiation, coincident with a loss of reliance on inflammatory signals, and a refined capacity of NK cells to target malaria parasites more precisely, particularly through antibody-dependent mechanisms.

Novel Immunoregulatory Functions of IL-18, an Accomplice of TGF-β1

TGF-β1 is a pleiotropic factor exerting a strong regulatory role in several cell types, including immune cells. In NK cells it profoundly alters the surface expression of crucial activating and chemokine receptors. To understand which soluble signals might better contrast these effects, we cultured human NK cells in the presence of TGF-β1 and different innate and adaptive cytokines, generally referred as “immunostimulatory”. These included IL-2, IL-15, IL-21, IL-27, and IL-18. Unexpectedly, IL-18 strengthened rather than contrasting important TGF-β1-mediated functions. In particular, IL-18 further reduced the expression of CX₃CR1 and NKp30, leading to the virtual abrogation of the triggering capability of this activating receptor. Moreover, IL-18 further increased the expression of CXCR4. The IL-18-mediated additive effect on NKp30 and CXCR4 expression involved transcriptional regulation and activation of MEK/ERK and/or p38MAPK. A proteomic approach quantified both surface and intracellular proteins significantly modified in cytokine-treated NK cells, thus giving global information on the biological processes involving TGF-β1 and IL-18. Our data support the concept that IL-18 may have a different behavior depending on the type of soluble factors characterizing the microenvironment. In a TGF-β1 rich milieu such as tumors, it may contribute to the impairment of both NK cells recruitment and killing capability.