Dendritic Cell-Derived IL-32α: A Novel Inhibitory Cytokine of NK Cell Function

Microbiota-Derived Short-Chain Fatty Acids Boost Antitumoral Natural Killer Cell Activity

Background: The intestinal microbiota can regulate numerous host functions, including the immune response. Through fermentation, the microbiota produces and releases microbial metabolites such as short-chain fatty acids (SCFAs), which can affect host homeostasis. There is growing evidence that the gut microbiome can have a major impact on cancer. Specific gut microbial composition and metabolites are associated with tumor status in the host. However, their effects on the antitumor response have scarcely been investigated. Natural killer (NK) cells play an important role in antitumor immunity due to their ability to directly identify and eliminate tumor cells. Methods: The aim of this study was to investigate the effects of SCFAs on antitumoral NK cell activity, using NK-92 cell line. Results: Here, we describe how SCFAs can boost antitumoral NK cell activity. The SCFAs induced the release of NK extracellular vesicles and reduced the secretion of the anti-inflammatory cytokine IL-10. The SCFAs also increased the cytotoxicity of the NK cells against multiple myeloma cells. Conclusions: Our results indicate, for the first time, the enormous potential of SCFAs in regulating antitumoral NK cell defense, where modulation of the SCFAs' production could play a fundamental role in cancer immunotherapy.

Ischemia-free liver transplantation improves the prognosis of recipients using functionally marginal liver grafts

BACKGROUND/AIMS

The shortage of donor liver hinders the development of liver transplantation. This study aimed to clarify the poor outcomes of functionally marginal liver grafts (FMLs) and provide evidence for the improvement of ischemia-free liver transplantation (IFLT) after FML transplantation.

METHODS

Propensity score matching was used to control for confounding factors. The outcomes of the control group and FML group were compared to demonstrate the negative impact of FMLs on liver transplantation patients. We compared the clinical improvements of the different surgical types. To elucidate the underlying mechanism, we conducted bioinformatic analysis based on transcriptome and single-cell profiles.

RESULTS

FMLs had a significantly greater hazard ratio (HR: 1.969, P=0.018) than did other marginal livers. A worse 90-day survival (Mortality: 12.3% vs. 5.0%, P=0.007) was observed in patients who underwent FML transplantation. Patients who received FMLs had a significant improvement in overall survival after IFLT (Mortality: 10.4% vs 31.3%, P=0.006). Pyroptosis and inflammation were inhibited in patients who underwent IFLT. The infiltration of natural killer cells was lower in liver grafts from these patients. Bulk transcriptome profiles revealed a positive relationship between IL-32 and Caspase 1 (R=0.73, P=0.01) and between IL-32 and Gasdermin D (R=0.84, P=0.0012).

CONCLUSION

FML is a more important negative prognostic parameter than other marginal liver parameters. IFLT might ameliorate liver injury in FMLs by inhibiting the infiltration of NK cells, consequently leading to the abortion of IL-32, which drives pyroptosis in monocytes and macrophages.

Role of interleukin‑32 in cancer progression (Review)

Interleukin (IL)-32 is induced by pro-inflammatory cytokines and promotes the release of inflammatory cytokines. Therefore, it can promote inflammatory responses. The present review article summarized the role of the receptors required for IL-32 action, the biological function of IL-32 and its mechanism of action in tumors. Moreover, it assessed the significance of aberrant IL-32 expression in associated diseases and analyzed the effects of IL-32 on four key types of cancer: Colorectal, gastric, breast and lung. However, the mechanism of action of IL-32 needs to be further demonstrated by assessing the role of this cytokine in cancer to elucidate novel and reliable targets for future cancer treatments.

StemDriver: a knowledgebase of gene functions for hematopoietic stem cell fate determination

StemDriver is a comprehensive knowledgebase dedicated to the functional annotation of genes participating in the determination of hematopoietic stem cell fate, available at http://biomedbdc.wchscu.cn/StemDriver/. By utilizing single-cell RNA sequencing data, StemDriver has successfully assembled a comprehensive lineage map of hematopoiesis, capturing the entire continuum from the initial formation of hematopoietic stem cells to the fully developed mature cells. Extensive exploration and characterization were conducted on gene expression features corresponding to each lineage commitment. At the current version, StemDriver integrates data from 42 studies, encompassing a diverse range of 14 tissue types spanning from the embryonic phase to adulthood. In order to ensure uniformity and reliability, all data undergo a standardized pipeline, which includes quality data pre-processing, cell type annotation, differential gene expression analysis, identification of gene categories correlated with differentiation, analysis of highly variable genes along pseudo-time, and exploration of gene expression regulatory networks. In total, StemDriver assessed the function of 23 839 genes for human samples and 29 533 genes for mouse samples. Simultaneously, StemDriver also provided users with reference datasets and models for cell annotation. We believe that StemDriver will offer valuable assistance to research focused on cellular development and hematopoiesis.

IL-32 as a potential biomarker and therapeutic target in skin inflammation

IL-32 is a recently described cytokine that performs a variety of functions under inflammatory conditions. Serum IL-32 has been shown to be elevated in several diseases, including type 2 diabetes, cancer, systemic lupus erythematosus, HIV infection, and atopic diseases including atopic dermatitis. There are nine different isoforms of IL-32, with IL-32γ being the most biologically active one. The following review summarizes the different roles of the various IL-32 isoforms in the context of skin inflammation, with a focus on atopic dermatitis.

Intrinsic and extrinsic factors determining natural killer cell fate: Phenotype and function

Natural killer (NK) cells are derived from hematopoietic stem cells. They belong to the innate lymphoid cell family, which is an important part of innate immunity. This family plays a role in the body mainly through the release of perforin, granzyme, and various cytokines and is involved in cytotoxicity and cytokine-mediated immune regulation. NK cells involved in normal immune regulation and the tumor microenvironment (TME) can exhibit completely different states. Here, we discuss the growth, development, and function of NK cells in regard to intrinsic and extrinsic factors. Intrinsic factors are those that influence NK cells to promote cell maturation and exert their effector functions under the control of internal metabolism and self-related genes. Extrinsic factors include the metabolism of the TME and the influence of related proteins on the "fate" of NK cells. This review targets the potential of NK cell metabolism, cellular molecules, regulatory genes, and other mechanisms involved in immune regulation. We further discuss immune-mediated tumor therapy, which is the trend of current research.

Induction of IL-32 in the immune response of keratinocytes to Mycobacterium marinum infection

Keratinocytes are the predominant cell type in the skin epidermis, and they not only protect the skin from the influence of external physical factors but also function as an immune barrier against microbial invasion. However, little is known regarding the immune defence mechanisms of keratinocytes against mycobacteria. Here, we performed single-cell RNA sequencing (scRNA-seq) on skin biopsy samples from patients with Mycobacterium marinum infection and bulk RNA sequencing (bRNA-seq) on M. marinum-infected keratinocytes in vitro. The combined analysis of scRNA-seq and bRNA-seq data revealed that several genes were upregulated in M. marinum-infected keratinocytes. Further in vitro validation of these genes by quantitative polymerase chain reaction and western blotting assay confirmed the induction of IL-32 in the immune response of keratinocytes to M. marinum infection. Immunohistochemistry also showed the high expression of IL-32 in patients' lesions. These findings suggest that IL-32 induction is a possible mechanism through which keratinocytes defend against M. marinum infection; this could provide new targets for the immunotherapy of chronic cutaneous mycobacterial infections.

Interleukin-32 in Pathogenesis of Atopic Diseases: Proinflammatory or Anti-Inflammatory Role?

Atopic diseases, such as atopic dermatitis (AD), allergic asthma (AA), and allergic rhinitis (AR), are increasingly becoming a worldwide issue. This atopic triad originates at an early age and on a multifactorial basis, causing significant discomfort to susceptible individuals. The global case number is now reaching new highs, so exploring immune system regulation and its components is becoming critical. One cytokine, interleukin-32 (IL-32), is involved in inflammation and regulation of the immune system. It has nine isoforms that show varying degrees of expression, both intracellularly and extracellularly. IL-32 is secreted by immune cells, such as monocytes, macrophages, natural killer cells, and T cells, and by nonimmune cells, including fibroblasts, keratinocytes, and endothelial cells. Its production is regulated and augmented by microorganisms, mitogens, and other cytokines. Early studies demonstrated that IL-32 was an immune regulator that functioned to protect against inflammatory diseases, including AD, AA, and AR, and proposed a proinflammatory role for IL-32 in immune regulation and symptom exacerbation. However, several later reports suggested that IL-32 is downregulated in inflammatory diseases and exerts an anti-inflammatory effect. This review article focuses on recent findings regarding the detrimental and protective roles of IL-32 in development and management of inflammatory diseases. The exact role of IL-32 in AD, AA, and AR still remains to be elucidated. Future research should explore new avenues of IL-32 functionality in human inflammatory diseases.

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.

Paracoccidioidesbrasiliensis induces IL-32 and is controlled by IL-15/IL-32/vitamin D pathway in vitro

Paracoccidioidomycosis (PCM) is a systemic fungal disease caused by Paracoccidioides spp., whose clinical outcome depends on immune response. Interleukin 32 (IL-32) is a cytokine present in inflammatory and infectious diseases, including bacterial, virus and protozoan infections. Its role in fungal disease remains unclear. The axis IL-15, IL-32 and vitamin D leads to microbicidal capacity against intracellular pathogens. Thus, the aims of this study were to investigate the production of IL-32 during Paracoccidioides spp. infection and whether this cytokine and IL-15 can increase P. brasiliensis control in a vitamin D dependent manner. IL-32 was highly detected in oral lesions from patients with PCM. In addition, high production of this cytokine was intracellularly detected in peripheral blood mononuclear cells (PBMCs) from healthy donors after exposure to particulated P. brasiliensis antigens (PbAg). The IL-32γ isoform was predominantly expressed, but there was mRNA alternative splicing for IL-32α isoform. The induction of IL-32 was dependent on Dectin-1 receptor. Infection of PBMCs with P. brasiliensis yeasts did not significantly induce IL-32 production even after activation with exogenous IFN-γ or IL-15 treatments. Although IL-15 was a potent inducer of IL-32 production, treatment with this cytokine did not increase the fungal control unless vitamin D was present in high levels. In this case, both IL-15 and IL-32 increased fungicidal activity of PBMCs. Together, data showed that IL-32 is present in lesions of PCM, PbAg induces IL-32, and the axis of IL-15/IL-32/vitamin D can contribute to control fungal infection. The data suggest that exposure to molecules from P. brasiliensis, as β-glucans, is needed to induce IL-32 production since only heat-killed and sonicated P. brasiliensis yeasts were able to increase IL-32, which was blocked by anti-Dectin-1 antibodies. This is the first description about IL-15/IL-32/vitamin D pathway role in P. brasiliensis infection.

Cytokines Orchestrating the Natural Killer-Myeloid Cell Crosstalk in the Tumor Microenvironment: Implications for Natural Killer Cell-Based Cancer Immunotherapy

Natural killer (NK) cells are endowed with germline-encoded receptors that enable them to detect and kill malignant cells without prior priming. Over the years, overwhelming evidence has identified an essential role for NK cells in tumor immune surveillance. More recently, clinical trials have also highlighted their potential in therapeutic settings. Yet, data show that NK cells can be dysregulated within the tumor microenvironment (TME), rendering them ineffective in eradicating the cancer cells. This has been attributed to immune suppressive factors, including the tumor cells per se, stromal cells, regulatory T cells, and soluble factors such as reactive oxygen species and cytokines. However, the TME also hosts myeloid cells such as dendritic cells, macrophages, neutrophils, and myeloid-derived suppressor cells that influence NK cell function. Although the NK-myeloid cell crosstalk can promote anti-tumor responses, myeloid cells in the TME often dysregulate NK cells via direct cell-to-cell interactions down-regulating key NK cell receptors, depletion of nutrients and growth factors required for NK cell growth, and secretion of metabolites, chemokines and cytokines that ultimately alter NK cell trafficking, survival, and cytotoxicity. Here, we review the complex functions of myeloid-derived cytokines in both supporting and suppressing NK cells in the TME and how NK cell-derived cytokines can influence myeloid subsets. We discuss challenges related to these interactions in unleashing the full potential of endogenous and adoptively infused NK cells. Finally, we present strategies aiming at improving NK cell-based cancer immunotherapies via pathways that are involved in the NK-myeloid cell crosstalk in the TME.

Molecular interactions and functions of IL-32

IL-32 is a multifaceted cytokine associated with several diseases and inflammatory conditions. Its expression is induced in response to cellular stress such as hypoxia, infections, and pro-inflammatory cytokines. IL-32 can be secreted from cells and can induce the production of pro-inflammatory cytokines from several cell types but are also described to have anti-inflammatory functions. The intracellular form of IL-32 is shown to play an important role in various cellular processes, including the defense against intracellular bacteria and viruses and in modulation of cell metabolism. In this review, we discuss current literature on molecular interactions of IL-32 with other proteins. We also review data on the role of intracellular IL-32 as a metabolic regulator and its role in antimicrobial host defense.

Genetic variation in Interleukin-32 influence the immune response against New World Leishmania species and susceptibility to American Tegumentary Leishmaniasis

Interleukin-32 is a novel inflammatory mediator that has been described to be important in the immunopathogenesis and control of infections caused by Leishmania parasites. By performing experiments with primary human cells in vitro, we demonstrate that the expression of IL-32 isoforms is dependent on the time exposed to L. amazonensis and L. braziliensis antigens. Moreover, for the first time we show the functional consequences of three different genetic variations in the IL32 (rs4786370, rs4349147, rs1555001) modulating IL-32γ expression, influencing innate and adaptive cytokine production after Leishmania exposure. Using a Brazilian cohort of 107 American Tegumentary Leishmaniasis patients and a control cohort of 245 healthy individuals, the IL32 rs4786370 genetic variant was associated with protection against ATL, whereas the IL32 rs4349147 was associated with susceptibility to the development of localized cutaneous and mucosal leishmaniasis. These novel insights may help improve therapeutic strategies and lead to benefits for patients suffering from Leishmania infections.

In this study, we described how IL-32 isoforms are crucial to host defense against new world Leishmania species infections. Furthermore, by accessing the genotype frequency of genetic variations in IL32 in a cohort of Brazilian patients with American Tegumentary Leishmaniasis (ATL) and controls, we have obtained indications that IL-32 is associated with disease susceptibility and the development of different clinical manifestations. Thus, this study provides us an extra evidence that the isoforms of IL-32 shape the immune response favoring the development of different cytokines produced by peripheral blood mononuclear cells that might contribute to skin/mucosal inflammation and host defense.

Understanding the basis of transcutaneous vaccine delivery

Under many circumstances, prophylactic immunizations are considered as the only possible strategy to control infectious diseases. Considerable efforts are typically invested in immunogen selection but, erroneously, the route of administration is not usually a major concern despite the fact that it can strongly influence efficacy. The skin is now considered a key component of the lymphatic system with tremendous potential as a target for vaccination. The purpose of this review is to present the immunological basis of the skin-associated lymphoid tissue, so as to provide understanding of the skin vaccination strategies. Several strategies are currently being developed for the transcutaneous delivery of antigens. The classical, mechanical or chemical disruptions versus the newest approaches based on microneedles for antigen delivery through the skin are discussed herein.

Human genes influence the interaction between Streptococcus mutans and host caries susceptibility: a genome-wide association study in children with primary dentition

Streptococcus mutans is a well-known cause of dental caries, due to its acidogenicity, aciduricity, and ability to synthesize exopolysaccharides in dental plaques. Intriguingly, not all children who carry S. mutans manifest caries, even with similar characteristics in oral hygiene, diet, and other environmental factors. This phenomenon suggests that host susceptibility potentially plays a role in the development of dental caries; however, the association between host genetics, S. mutans, and dental caries remains unclear. Therefore, this study examined the influence of host gene-by-S. mutans interaction on dental caries. Genome-wide association analyses were conducted in 709 US children (<13 years old), using the dbGap database acquired from the center for oral health research in appalachia (COHRA) and the Iowa Head Start programmes (GEIRS). A generalized estimating equation was used to examine the gene-by-S. mutans interaction effects on the outcomes (decayed and missing/filled primary teeth due to caries). Sequentially, the COHRA and GEIRS data were used to identify potential interactions and replicate the findings. Three loci at the genes interleukin 32 (IL32), galactokinase 2 (GALK2), and CUGBP, Elav-like family member 4 (CELF4) were linked to S. mutans carriage, and there was a severity of caries at a suggestive significance level among COHRA children (P < 9 × 10-5), and at a nominal significance level among GEIRS children (P = 0.047-0.001). The genetic risk score that combined the three loci also significantly interacted with S. mutans (P < 0.000 1). Functional analyses indicated that the identified genes are involved in the host immune response, galactose carbohydrate metabolism, and food-rewarding system, which could potentially be used to identify children at high risk for caries and to develop personalized caries prevention strategies.

Endometrial Tumor Microenvironment Alters Human NK Cell Recruitment, and Resident NK Cell Phenotype and Function

Endometrial Cancer is the most common cancer in the female genital tract in developed countries, and with its increasing incidence due to risk factors such as aging and obesity tends to become a public health issue. However, its immune environment has been less characterized than in other tumors such as breast cancers. NK cells are cytotoxic innate lymphoid cells that are considered as a major anti-tumoral effector cell type which function is drastically altered in tumors which participates to tumor progression. Here we characterize tumor NK cells both phenotypically and functionally in the tumor microenvironment of endometrial cancer. For that, we gathered endometrial tumors, tumor adjacent healthy tissue, blood from matching patients and healthy donor blood to perform comparative analysis of NK cells. First we found that NK cells were impoverished in the tumor infiltrate. We then compared the phenotype of NK cells in the tumor and found that tumor resident CD103⁺ NK cells exhibited more co-inhibitory molecules such as Tigit, and TIM-3 compared to recruited CD103⁻ NK cells and that the expression of these molecules increased with the severity of the disease. We showed that both chemokines (CXCL12, IP-10, and CCL27) and cytokines profiles (IL-1β and IL-6) were altered in the tumor microenvironment and might reduce NK cell function and recruitment to the tumor site. This led to hypothesize that the tumor microenvironment reduces resident NK cells cytotoxicity which we confirmed by measuring cytotoxic effector production and degranulation. Taken together, our results show that the tumor microenvironment reshapes NK cell phenotype and function to promote tumor progression.

Interleukin 32 expression in human melanoma

Background

Various proinflammatory cytokines can be detected within the melanoma tumor microenvironment. Interleukin 32 (IL32) is produced by T cells, NK cells and monocytes/macrophages, but also by a subset of melanoma cells. We sought to better understand the biology of IL32 in human melanoma.

Methods

We analyzed RNA sequencing data from 53 in-house established human melanoma cell lines and 479 melanoma tumors from The Cancer Genome Atlas dataset. We evaluated global gene expression patterns associated with IL32 expression. We also evaluated the impact of proinflammatory molecules TNFα and IFNγ on IL32 expression and dedifferentiation in melanoma cell lines in vitro. In order to study the transcriptional regulation of IL32 in these cell lines, we cloned up to 10.5 kb of the 5′ upstream region of the human IL32 gene into a luciferase reporter vector.

Results

A significant proportion of established human melanoma cell lines express IL32, with its expression being highly correlated with a dedifferentiation genetic signature (high AXL/low MITF). Non IL32-expressing differentiated melanoma cell lines exposed to TNFα or IFNγ can be induced to express the three predominant isoforms (α, β, γ) of IL32. Cis-acting elements within this 5′ upstream region of the human IL32 gene appear to govern both induced and constitutive gene expression. In the tumor microenvironment, IL32 expression is highly correlated with genes related to T cell infiltration, and also positively correlates with high AXL/low MITF dedifferentiated gene signature.

Conclusions

Expression of IL32 in human melanoma can be induced by TNFα or IFNγ and correlates with a treatment-resistant dedifferentiated genetic signature. Constitutive and induced expression are regulated, in part, by cis-acting sequences within the 5′ upstream region.

Electronic supplementary material

The online version of this article (10.1186/s12967-019-1862-y) contains supplementary material, which is available to authorized users.

The Biology and Role of Interleukin-32 in Tuberculosis

Tuberculosis, caused by Mycobacterium tuberculosis, remains a leading cause of morbidity and mortality globally, with nearly 10.4 million new cases of incidence and over 1.7 million deaths annually. Drug-resistant M. tuberculosis strains, especially multidrug-resistant or extensively drug-resistant strains, have further intensified the problem associated with tuberculosis control. Host-directed therapy is a promising alternative for tuberculosis control. IL-32 is increasingly recognized as an important host molecule against tuberculosis. In this review, we highlight the proinflammatory properties of IL-32 and the mode of action of IL-32 in mycobacterial infections to inspire the development of novel immunity-based countermeasures and host-directed therapies against tuberculosis.

Key gene co-expression modules and functional pathways involved in the pathogenesis of Graves' disease

Graves' disease (GD) is a common autoimmune thyroid disease characterized by positive thyroid stimulating hormone receptor antibody. To better understand its molecular pathogenesis, we adopted the weighted gene co-expression network analysis to reveal co-expression modules of key genes involved in the pathogenesis of GD, protein-protein interaction network analysis to identify the hub genes related to GD development and functional analyses to explore their possible functions. Our results showed that 1) a total of 2667 differentially expressed genes in our microarray study and 16 different gene co-expression modules were associated with GD, and 2) the most significant module was associated with the percentage of macrophages, T follicular helper cells and CD4⁺ memory T cells and mainly enriched in immune regulation and immune response. Overall, our study reveals several key gene co-expression modules and functional pathways involved in GD, which provides some novel insights into the pathogenesis of GD.

Interleukin-32 promotes detachment and activation of human Langerhans cells in a human skin explant model

BACKGROUND

Cross-talk between skin keratinocytes (KCs) and Langerhans cells (LCs) plays a fundamental role in the body's first line of immunological defences. However, the mechanism behind the interaction between these two major epidermal cells is unknown. Interleukin (IL)-32 is produced in inflammatory skin disorders. We questioned the role of IL-32 in the epidermis.

OBJECTIVES

We aimed to determine the role of IL-32 produced by KCs on surrounding LCs.

METHODS

We used an ex vivo human explant model from healthy donors and investigated the role of IL-32 on LC activation using imaging, flow cytometry, reverse transcriptase quantitative polymerase chain reaction and small interfering (si)RNA treatment.

RESULTS

Modified vaccinia virus ankara (MVA) infection induced KC death alongside the early production of the proinflammatory cytokine IL-32. We demonstrated that IL-32 produced by MVA-infected KCs induced modest but significant morphological changes in LCs and downregulation of adhesion molecules, such as epithelial cell adhesion molecule and very late antigen-4, and CXCL10 production. The treatment of KCs with IL-32-specific siRNA, and anti-IL-32 blocking antibody significantly inhibited LC activation, demonstrating the role of IL-32 in LC activation. We also found that some Toll-like receptor ligands induced a very high level of IL-32 production by KCs, which initiated LC activation.

CONCLUSIONS

We propose, for the first time, that IL-32 is a molecular link between KCs and LCs in healthy skin, provoking LC migration from the epidermis to the dermis prior to their migration to the draining lymph nodes.