Structural basis for receptor sharing and activation by interleukin-20 receptor-2 (IL-20R2) binding cytokines

Oncolytic Newcastle disease virus carrying the IL24 gene exerts antitumor effects by inhibiting tumor growth and vascular sprouting

The second-leading cause of death, cancer, poses a significant threat to human life. Innovations in cancer therapies are crucial due to limitations in traditional approaches. Newcastle disease virus (NDV), a nonpathogenic oncolytic virus, exhibits multifunctional anticancer properties by selectively infecting, replicating, and eliminating tumor cells. To enhance NDV's antitumor activity, four oncolytic NDV viruses were developed, incorporating IL24 and/or GM-CSF genes at different gene loci using reverse genetics. In vitro experiments revealed that oncolytic NDV virus augmented the antitumor efficacy of the parental virus rClone30, inhibiting tumor cell proliferation, inducing tumor cell fusion, and promoting apoptosis. Moreover, NDV carrying the IL24 gene inhibited microvessel formation in CAM experiments. Evaluation in a mouse model of liver cancer confirmed the therapeutic efficacy of oncolytic NDV viral therapy. Tumors in mice treated with oncolytic NDV virus significantly decreased in size, accompanied by tumor cell detachment and apoptosis evident in pathological sections. Furthermore, oncolytic NDV virus enhanced T cell and dendritic cell production and substantially improved the survival rate of mice with hepatocellular carcinoma, with rClone30-IL24(P/M) demonstrating significant therapeutic effects. This study establishes a basis for utilizing oncolytic NDV virus as an antitumor agent in clinical practice.

Drosophila cytokine GBP2 exerts immune responses and regulates GBP1 expression through GPCR receptor Mthl10

Growth-blocking peptide (GBP), an insect cytokine, was first found in armyworm Mythimna separata. A functional analogue of GBP, stress-responsive peptide (SRP), was also identified in the same species. SRP gene expression has been demonstrated to be enhanced by GBP, indicating that both cytokines are organized within a hierarchical regulatory network. Although GBP1 (CG15917) and GBP2 (CG11395) have been identified in Drosophila melanogaster, immunological functions have only been characterized for GBP1. It is expected that the biological responses of two structurally similar peptides should be coordinated, but there is little information on this topic. Here, we demonstrate that GBP2 replicates the GBP1-mediated cellular immune response from Drosophila S2 cells. Moreover, the GBP2-induced response was silenced by pre-treatment with dsRNA targeting the GBP receptor gene, Mthl10. Furthermore, treatment of S2 cells with GBP2 enhanced GBP1 expression levels, but GBP1 did not affect GBP2 expression. GBP2 derived enhancement of GBP1 expression was not observed in the presence of GBP1, indicating that GBP2 is an upstream expressional regulator of a GBP1/GBP2 cytokine network. GBP2-induced enhancement of GBP1 expression was not observed in Mthl10 knockdown cells. Enhancement of GBP2 expression was observed in both Drosophila larvae and S2 cells under heat stress conditions; expressional enhancement of both GBP1 and GBP2 was eliminated in Mthl10 knockdown cells and larvae. Finally, Ca2+ mobilization assay in GCaMP3-expressing S2 cells demonstrated that GBP2 mobilizes Ca2+ upstream of Mthl10. Our finding revealed that Drosophila GBP1 and GBP2 control immune responses as well as their own expression levels through a hierarchical cytokine network, indicating that Drosophila GBP1/GBP2 system can be a simple model that is useful to investigate the detailed regulatory mechanism of related cytokine complexes.

Characterization of fish-specific IFNγ-related binding with a unique receptor complex and signaling through a novel pathway

Unlike mammals, fish express two type II interferons, IFNγ and fish-specific IFNγ (IFNγ-related or IFNγrel). We previously reported the presence of two IFNγrel genes, IFNγrel 1 and IFNγrel 2, which exhibit potent antiviral activity in the Ginbuna crucian carp, Carassius auratus langsdorfii. We also found that IFNγrel 1 increased allograft rejection; however, the IFNγrel 1 receptor(s) and signaling pathways underlying this process have not yet been elucidated. In this study, we examined the unique signaling mechanism of IFNγrel 1 and its receptors. The phosphorylation and transcriptional activation of STAT6 in response to recombinant Ginbuna IFNγrel 1 (rgIFNγrel 1) was observed in Ginbuna-derived cells. Binding of rgIFNγrel 1 to Class II cytokine receptor family members (Crfbs), Crfb5 and Crfb17, which are also known as IFNAR1 and IFNGR1-1, respectively, was detected by flow cytometry. Expression of the IFNγrel 1-inducible antiviral gene, Isg15, was highest in Crfb5- and Crfb17-overexpressing GTS9 cells. Dimerization of Crfb5 and Crfb17 was detected by chemical crosslinking. The results indicate that IFNγrel 1 activates Stat6 through an interaction with unique pairs of receptors, Crfb5 and Crfb17. Indeed, this cascade is distinct from not only that of IFNγ but also that of known IFNs in other vertebrates. IFNs may be classified by their receptor and signal transduction pathways. Taken together, IFNγrel 1 may be classified as a novel type of IFN family member in vertebrates. Our findings provide important information on interferon gene evolution in bony fish.

Structural insights into IL-11-mediated signalling and human IL6ST variant-associated immunodeficiency

IL-11 and IL-6 activate signalling via assembly of the cell surface receptor gp130; however, it is unclear how signals are transmitted across the membrane to instruct cellular responses. Here we solve the cryoEM structure of the IL-11 receptor recognition complex to discover how differences in gp130-binding interfaces may drive signalling outcomes. We explore how mutations in the IL6ST gene encoding for gp130, which cause severe immune deficiencies in humans, impair signalling without blocking cytokine binding. We use cryoEM to solve structures of both IL-11 and IL-6 complexes with a mutant form of gp130 associated with human disease. Together with molecular dynamics simulations, we show that the disease-associated variant led to an increase in flexibility including motion within the cytokine-binding core and increased distance between extracellular domains. However, these distances are minimized as the transmembrane helix exits the membrane, suggesting a stringency in geometry for signalling and dimmer switch mode of action.

Deciphering the Receptor-Mediated Signaling Pathways of Interleukin-19 and Interleukin-20

Interleukin-19 (IL-19) and Interleukin-20 (IL-20) are inflammatory cytokines belonging to the IL-10 family with immunoregulatory properties. Emerging evidence highlights the importance of association of these cytokines with both immunological and inflammatory disorders, including chronic inflammation, cardiac dysfunction, and cancer. IL-19 and IL-20 bind to the heterodimeric receptor complex and induce multiple downstream signaling cascades by activating the signal transducer and activator of transcription 3 (STAT3), Jun N-terminal kinase (JNK), extracellular signal-regulated kinase (ERK), AKT serine/threonine kinase 1 (AKT1), and NFKB inhibitor alpha (NFKBIA), leading to proinflammatory and anti-inflammatory reactions in cancer, inflammation, tumor microenvironment, and infectious diseases. Considering the significant role of these cytokines, we integrated its cellular signaling network by combining multiomics molecular events associated with 56 molecules of induced by IL-19 and 156 molecules of by IL-20. The reactions of these signaling events are classified into enzyme catalysis/post-translational modifications, activation/inhibition events, molecular associations, gene regulations at the mRNA and protein level, and the protein translocation events. We believe that this signaling pathway map would serve as a knowledge base, that aid researchers and clinicians to understand and explore the intricate mechanisms and identify novel signaling components and therapeutic targets for diseases associated with dysregulated IL-19 and IL-20 signaling.

Molecular cloning, characterization and gene expression analysis of twelve interleukins in obscure puffer Takifugu obscurus

Interleukins (ILs) are a subgroup of secreted cytokines, which are molecules involved in the intercellular regulation of the immune system. In this study, 12 IL homologs were cloned and functionally identified from obscure puffer Takifugu obscurus, and they were termed as ToIL-1β, ToIL-1, ToIL-6, ToIL-10, ToIL-11, ToIL-12, ToIL-17, ToIL-18, ToIL-20, ToIL-24, ToIL-27, and ToIL-34. Multiple alignment results showed that except for ToIL-24 and ToIL-27, other deduced ToIL proteins shared typical characteristics and structure with other known fish ILs. Phylogenetic analysis revealed that 12 ToILs were evolutionarily closely related to their counterparts in other selected vertebrates. Tissue distribution assay demonstrated that the mRNA transcripts of most ToIL genes were constitutively expressed in all tissues examined, with relatively high expression in immune tissues. Following Vibrio harveyi and Staphylococcus aureus infection, the expression levels of 12 ToILs in the spleen and liver were significantly upregulated, and their response over time varied. Taken together, these data were discussed accordingly with the ToIL expression and the immune response under the different situations tested. The results suggest that the 12 ToIL genes are involved in the antibacterial immune response in T. obscurus.

Characterization of IL-10 Family of Cytokines in Acute and Convalescent COVID-19 Individuals

Cytokines are major players in orchestrating inflammation, disease pathogenesis, and severity during COVID-19. Members of the interleukin (IL)-10 family of cytokines play important roles in regulating immune responses to various inflammatory and infectious diseases. However, the role of the IL-10 family of cytokines in COVID-19 remains elusive. Hence, we determined the plasma levels of the IL-10 family of cytokines (IL-10, IL-19, IL-20, IL-22, and IL-24) in 7 groups of COVID-19 individuals, based on days since real-time reverse transcriptase-polymerase chain reaction confirmation of SARS-CoV-2 infection. Our data show that the levels of IL-10, IL-19, IL-20, IL-22, and IL-24 cytokines decreased from days 15-30 to days 61-90 and plateaued thereafter. Severe COVID-19 patients exhibit increased plasma levels of IL-10, IL-19, IL-20, IL-22, and IL-24 compared to mild patients. Thus, our study provides evidence of alterations in the plasma levels of the IL-10 family of cytokines in convalescent COVID-19 individuals.

Sustained and intermittent hypoxia differentially modulate primary monocyte immunothrombotic responses to IL-1β stimulation

Venous thromboembolism (VTE) is a leading cause of preventable deaths in hospitals, and its incidence is not decreasing despite extensive efforts in clinical and laboratory research. Venous thrombi are primarily formed in the valve pockets of deep veins, where activated monocytes play a crucial role in bridging innate immune activation and hemostatic pathways through the production of inflammatory cytokines, chemokines, and tissue factor (TF) - a principal initiator of coagulation. In the valve pocket inflammation and hypoxia (sustained/intermittent) coexist, however their combined effects on immunothrombotic processes are poorly understood. Inflammation is strongly associated with VTE, while the additional contribution of hypoxia remains largely unexplored. To investigate this, we modelled the intricate conditions of the venous valve pocket using a state-of-the-art hypoxia chamber with software-controlled oxygen cycling. We comprehensively studied the effects of sustained and intermittent hypoxia alone, and in combination with VTE-associated inflammatory stimuli on primary monocytes. TF expression and activity was measured in monocytes subjected to sustained and intermittent hypoxia alone, or in combination with IL-1β. Monocyte responses were further analyzed in detailed by RNA sequencing and validated by ELISA. Stimulation with IL-1β alone promoted both transcription and activity of TF. Interestingly, the stimulatory effect of IL-1β on TF was attenuated by sustained hypoxia, but not by intermittent hypoxia. Our transcriptome analysis further confirmed that sustained hypoxia limited the pro-inflammatory response induced by IL-1β, and triggered a metabolic shift in monocytes. Intermittent hypoxia alone had a modest effect on monocyte transcript. However, in combination with IL-1β intermittent hypoxia significantly altered the expression of 2207 genes and enhanced the IL-1β-stimulatory effects on several chemokine and interleukin genes (e.g., IL-19, IL-24, IL-32, MIF), as well as genes involved in coagulation (thrombomodulin) and fibrinolysis (VEGFA, MMP9, MMP14 and PAI-1). Increased production of CCL2, IL-6 and TNF following stimulation with intermittent hypoxia and IL-1β was confirmed by ELISA. Our findings provide valuable insights into how the different hypoxic profiles shape the immunothrombotic response of monocytes and shed new light on the early events in the pathogenesis of venous thrombosis.

Molecular and cellular factors determining the functional pleiotropy of cytokines

Cytokines are soluble factors vital for mammalian physiology. Cytokines elicit highly pleiotropic activities, characterized by their ability to induce a wide spectrum of functional responses in a diverse range of cell subsets, which makes their study very challenging. Cytokines activate signalling via receptor dimerization/oligomerization, triggering activation of the JAK (Janus kinase)/STAT (signal transducer and activator of transcription) signalling pathway. Given the strong crosstalk and shared usage of key components of cytokine signalling pathways, a long-standing question in the field pertains to how functional diversity is achieved by cytokines. Here, we discuss how biophysical - for example, ligand-receptor binding affinity and topology - and cellular - for example, receptor, JAK and STAT protein levels, endosomal compartment - parameters contribute to the modulation and diversification of cytokine responses. We review how these parameters ultimately converge into a common mechanism to fine-tune cytokine signalling that involves the control of the number of Tyr residues phosphorylated in the receptor intracellular domain upon cytokine stimulation. This results in different kinetics of STAT activation, and induction of specific gene expression programs, ensuring the generation of functional diversity by cytokines using a limited set of signalling intermediaries. We describe how these first principles of cytokine signalling have been exploited using protein engineering to design cytokine variants with more specific and less toxic responses for immunotherapy.

Grass carp IL-20 binds to IL-20R2 but induces STAT3 phosphorylation via IL-20R1

IL-20 is a pleiotropic cytokine that belongs to the IL-10 family and has a variety of biological functions in tissue homeostasis and regulation of host immune defenses. It signals through a heterodimeric receptor composed of a subunit with a long intracellular domain (R1 type receptor) and a subunit with a short intracellular domain (R2 type receptor). In this study, the R1 type receptor (CiIL-20R1/CRFB8) and the R2 type receptor (CiIL-20R2/CRFB16) were identified in grass carp Ctenopharyngodon idella. Expression analysis revealed that IL-20R2 was highly expressed in the gills and skin in healthy fish. Infection with Flavobacterium columnare resulted in the downregulation of both receptors in the gill at 48 and 72 h, whilst infection with grass carp reovirus induced their expression in the head kidney and spleen at 72 h. In the primary head kidney leucocytes, the expression levels of IL-20R1 and IL-20R2 were decreased after stimulation with 250 ng/mL IL-1β but not affected by IFN-γ. Co-immunoprecipitation analysis showed that CiIL-20R2/CRFB16 but not CiIL-20R1/CRFB8 bound to CiIL-20L. Furthermore, it was shown that CiIL-20R1/CRFB8 was responsible for activating the phosphorylation of STAT3, whilst CiIL-20R2/CRFB16 was not involved. Structural modeling analysis showed that key residues involved in the interaction between IL-20 and receptors were highly conserved between grass carp and humans, suggesting that the signal transduction and functions of IL-20/IL-20R axis are evolutionarily conserved.

Immune checkpoint of B7-H3 in cancer: from immunology to clinical immunotherapy

Immunotherapy for cancer is a rapidly developing treatment that modifies the immune system and enhances the antitumor immune response. B7-H3 (CD276), a member of the B7 family that plays an immunoregulatory role in the T cell response, has been highlighted as a novel potential target for cancer immunotherapy. B7-H3 has been shown to play an inhibitory role in T cell activation and proliferation, participate in tumor immune evasion and influence both the immune response and tumor behavior through different signaling pathways. B7-H3 expression has been found to be aberrantly upregulated in many different cancer types, and an association between B7-H3 expression and poor prognosis has been established. Immunotherapy targeting B7-H3 through different approaches has been developing rapidly, and many ongoing clinical trials are exploring the safety and efficacy profiles of these therapies in cancer. In this review, we summarize the emerging research on the function and underlying pathways of B7-H3, the expression and roles of B7-H3 in different cancer types, and the advances in B7-H3-targeted therapy. Considering different tumor microenvironment characteristics and results from preclinical models to clinical practice, the research indicates that B7-H3 is a promising target for future immunotherapy, which might eventually contribute to an improvement in cancer immunotherapy that will benefit patients.

Genomic basis for early-life mortality in sharpsnout seabream

Mortality at early life stages of fishes is common in nature and can be shaped by stochastic and selective processes. Selective mortality has rarely been assessed in natural conditions but can now be studied by combining genomic data with information on different life stages that realates to fitness. Here we investigate selective mortality between settlers and six-month survivors of the sharpsnout seabream by genotype-phenotype/environmental association studies in three localities along a geographic gradient. We gathered information on 105 individuals at 85,031 SNPs, obtained from individual based 2b-RAD libraries, as well as 9 phenotypic and environmental variables derived from individual otolith readings. We found common signals across localities for potential selection, such as lower survival rates for individuals hatching earlier, growing faster and experiencing higher temperatures during their planktonic phase. We identified 122 loci with parallel significant association to phenotypic and environmental variables. Importantly, one of these loci mapped to the exonic region of the il20rb, a gene involved in immune response, in the phylogenetically closest reference genome, showing parallel frequency changes in non-synonymous mutations in the three studied populations. Further temporal assessments are needed to understand how polymorphisms that are key to selective mortality are maintained.

IL-24 intrinsically regulates Th17 cell pathogenicity in mice

In certain instances, Th17 responses are associated with severe immunopathology. T cell–intrinsic mechanisms that restrict pathogenic effector functions have been described for type 1 and 2 responses but are less well studied for Th17 cells. Here, we report a cell-intrinsic feedback mechanism that controls the pathogenicity of Th17 cells. Th17 cells produce IL-24, which prompts them to secrete IL-10. The IL-10–inducing function of IL-24 is independent of the cell surface receptor of IL-24 on Th17 cells. Rather, IL-24 is recruited to the inner mitochondrial membrane, where it interacts with the NADH dehydrogenase (ubiquinone) 1 α subcomplex subunit 13 (also known as Grim19), a constituent of complex I of the respiratory chain. Together, Grim19 and IL-24 promote the accumulation of STAT3 in the mitochondrial compartment. We propose that IL-24–guided mitochondrial STAT3 constitutes a rheostat to blunt extensive STAT3 deflections in the nucleus, which might then contribute to a robust IL-10 response in Th17 cells and a restriction of immunopathology in experimental autoimmune encephalomyelitis.

Interleukin 20 receptor subunit beta (IL20RB) predicts poor prognosis and regulates immune cell infiltration in clear cell renal cell carcinoma

BACKGROUND AND OBJECTIVE

Emerging evidence has proven the robust role of tumor mutation burden (TMB) and immune cell infiltration (ICI) in cancer immunotherapy. However, the precise effect of TMB and ICI on clear cell renal cell carcinoma (ccRCC) remains elusive and merits further investigation. Therefore, we aim to identify the TMB-related genes in predicting prognosis and to explore the potential mechanisms of the identified Interleukin 20 receptor subunit beta (IL20RB) in ICI in ccRCC.

METHOD

The relative information of patients with ccRCC was obtained from The Cancer Genome Atlas database (TCGA). Immune-related genes were downloaded from the Immunology Database and Analysis Portal database. Cox regression analysis was used to identify prognosis-related immune genes for ccRCC. The relationship of IL20RB expression levels with clinicopathological parameters was analyzed using the "limma" and "survival" packages. Gene Expression Omnibus (GEO) and International Cancer Genome Consortium (ICGC) databases were used as external validation. Quantitative Real-time PCR (qRT-PCR) and western blots were used to validate the expression levels of IL20RB in tumor cells. Cell counting kit-8 (CCK-8) assay and colony formation assay were used to examine the effect of IL20RB on the viability of ccRCC cells. Gene set enrichment analysis (GSEA) was introduced for the analysis of IL20RB-related signaling pathways. Tumor Immune Estimation Resource (TIMER) and Tumor and Immune System Interaction Database (TISIDB) were utilized to determine the correlation of IL20RB expression levels with tumor-infiltrating immune cells (TIICs).

RESULTS

IL20RB was significantly overexpressed in different ccRCC tissues and cells. High IL20RB expression in ccRCC patients was associated with short overall survival, high tumor grade, and advanced TNM stage. After knockdown of IL20RB with small interfering RNA (siRNA) technology, ccRCC cells' proliferation was significantly attenuated. Moreover, overexpression of IL20RB could increase the infiltration level of several immune cells, especially T follicular helper cells (Tfh), and overexpressed Tfh cells were correlated with poor prognosis in ccRCC.

CONCLUSIONS

IL20RB may function as an immune-associated therapeutic target for it determines cancer progression and regulates immune cell infiltration in ccRCC.

IL-20 promotes cutaneous inflammation and peripheral itch sensation in atopic dermatitis

Atopic dermatitis (AD) is a chronic skin disease, which is associated with intense itch, skin barrier dysfunction and eczematous lesions. Aberrant IL‐20 expression has been implicated in numerous inflammatory diseases, including psoriasis. However, the role of IL‐20 in AD remains unknown. Here, RNA‐seq, Q‐PCR, and immunocytochemistry were utilized to examine disease‐driven changes of IL‐20 and its cognate receptor subunits in skin from healthy human subjects, AD patients and murine AD‐models. Calcium imaging, knockdown and cytokine array were used to investigate IL‐20‐evoked responses in keratinocytes and sensory neurons. The murine cheek model and behavioral scoring were employed to evaluate IL‐20‐elicited sensations in vivo. We found that transcripts and protein of IL‐20 were upregulated in skin from human AD and murine AD‐like models. Topical MC903 treatment in mice ear enhanced IL‐20R1 expression in the trigeminal sensory ganglia, suggesting a lesion‐associated and epidermal‐driven mechanism for sensitization of sensory IL‐20 signaling. IL‐20 triggered calcium influx in both keratinocytes and sensory neurons, and promoted their AD‐related molecule release and transcription of itch‐related genes. In sensory neurons, IL‐20 application increased TLR2 transcripts, implicating a link between innate immune response and IL‐20. In a murine cheek model of acute itch, intradermal injection IL‐20 and IL‐13 elicited significant itch‐like behavior, though only when co‐injected. Our findings provide novel insights into IL‐20 function in peripheral (skin‐derived) itch and clinically relevant intercellular neuron‐epidermal communication, highlighting a role of IL‐20 signaling in the pathophysiology of AD, thus forming a new basis for the development of a novel antipruritic strategy via interrupting IL‐20 epidermal pathways.

Protein kinase R is an innate immune sensor of proteotoxic stress via accumulation of cytoplasmic IL-24

Proteasome dysfunction can lead to autoinflammatory disease associated with elevated type I interferon (IFN-αβ) and NF-κB signaling; however, the innate immune pathway driving this is currently unknown. Here, we identified protein kinase R (PKR) as an innate immune sensor for proteotoxic stress. PKR activation was observed in cellular models of decreased proteasome function and in multiple cell types from patients with proteasome-associated autoinflammatory disease (PRAAS). Furthermore, genetic deletion or small-molecule inhibition of PKR in vitro ameliorated inflammation driven by proteasome deficiency. In vivo, proteasome inhibitor-induced inflammatory gene transcription was blunted in PKR-deficient mice compared with littermate controls. PKR also acted as a rheostat for proteotoxic stress by triggering phosphorylation of eIF2α, which can prevent the translation of new proteins to restore homeostasis. Although traditionally known as a sensor of RNA, under conditions of proteasome dysfunction, PKR sensed the cytoplasmic accumulation of a known interactor, interleukin-24 (IL-24). When misfolded IL-24 egress into the cytosol was blocked by inhibition of the endoplasmic reticulum-associated degradation pathway, PKR activation and subsequent inflammatory signaling were blunted. Cytokines such as IL-24 are normally secreted from cells; therefore, cytoplasmic accumulation of IL-24 represents an internal danger-associated molecular pattern. Thus, we have identified a mechanism by which proteotoxic stress is detected, causing inflammation observed in the disease PRAAS.

De novo developed protein binders mimicking Interferon lambda signaling

We hereby describe the process of design and selection of nonantibody protein binders mimicking cytokine signaling. We chose to mimic signaling of IFN-λ1, type 3 interferon (also known as IL-29) for its novelty and the importance of its biological functions. All four known interferons λ signal through binding to the extracellular domains of IL-28 receptor 1 (IL-28R1) and IL-10 receptor 2 (IL-10R2). Our binders were therefore trained to bind both receptors simultaneously. The bifunctional binder molecules were developed by yeast display, a method of directed evolution. The signaling capacity of the bivalent binders was tested by measuring phosphorylation of the JAK/STAT signaling pathway and production of mRNA of six selected genes naturally induced by IFN- λ1 in human cell lines. The newly developed bivalent binders offer opportunities to study cytokine-related biological functions and modulation of the cell behavior by receptor activation on the cell surfaces alternative to the use of natural IFN-λ.

Evaluation of the relationship between anti-inflammatory cytokines and adverse cardiac remodeling after myocardial infarction

Aim    To clarify the role of interleukin (IL) - 10 and members of its subfamily (IL-19 and IL-26) in cardiac remodeling during the post-myocardial infarction (MI) period.Material and methods    A total of 45 patients with ST-segment elevation MI were enrolled. Serum cytokine concentrations were measured at the first day and 14 days post-MI. Left ventricular (LV) reverse remodeling (RR) was defined as the reduction of LV end-diastolic volume or LV end-systolic volume by ≥ 12 % in cardiac magnetic resonance images at 6‑mo follow-up. A 12 % increase was defined as adverse remodeling (AR).Results    The post-MI first-day median IL-10 (9.7 pg / ml vs. 17.6 pg / ml, p<0.001), median IL-19 (28.7 pg / ml vs. 36.9 pg / ml, p<0.001), and median IL-26 (47.8 pg / ml vs. 90.7 pg / ml, p<0.001) were lower in the RR group compared to the AR group. There was a significant decrease in the concentration of anti-inflammatory cytokines in the AR group from the first to the 14 days post-MI. However, no significant change was observed in the RR group. Regression analysis revealed that a low IL-10 concentration on the post-MI first day was related to RR (OR=0.76, p=0.035). A 1 % increase in change of IL-10 concentration increased the probability of RR by 1.07 times.Conclusion    The concentrations of cytokines were higher in the AR group, but this elevation was not sustained and significantly decreased for the 14 days post-MI. In the RR group, the concentrations of cytokines did not change and stable for the 14 days post-MI. As a reflection of this findings, stable IL-10 concentration may play a role the improvement of cardiac functions.

Expression of IL-20 Receptor Subunit β Is Linked to EAE Neuropathology and CNS Neuroinflammation

Considerable clinical evidence supports that increased blood-brain barrier (BBB) permeability is linked to immune extravasation of CNS parenchyma during neuroinflammation. Although BBB permeability and immune extravasation are known to be provoked by vascular endothelial growth factor-A (i.e., VEGF-A) and C-X-C motif chemokine ligand 12 (CXCL12), respectively, the mechanisms that link both processes are still elusive. The interleukin-20 (i.e., IL-20) cytokine signaling pathway was previously implicated in VEGF-mediated angiogenesis and is known to induce cellular response by way of signaling through IL-20 receptor subunit β (i.e., IL-20RB). Dysregulated IL-20 signaling is implicated in many inflammatory pathologies, but it's contribution to neuroinflammation has yet to be reported. We hypothesize that the IL-20 cytokine, and the IL cytokine subfamily more broadly, play a key role in CNS neuroinflammation by signaling through IL-20RB, induce VEGF activity, and enhance both BBB-permeability and CXCL12-mediated immune extravasation. To address this hypothesis, we actively immunized IL-20RB^-/- mice and wild-type mice to induce experimental autoimmune encephalomyelitis (EAE) and found that IL-20RB^-/- mice showed amelioration of disease progression compared to wild-type mice. Similarly, we passively immunized IL-20RB^-/- mice and wild-type mice with myelin-reactive Th1 cells from either IL-20RB^-/- and wild-type genotype. Host IL-20RB^-/- mice showed lesser disease progression than wild-type mice, regardless of the myelin-reactive Th1 cells genotype. Using multianalyte bead-based immunoassay and ELISA, we found distinctive changes in levels of pro-inflammatory cytokines between IL-20RB^-/- mice and wild-type mice at peak of EAE. We also found detectable levels of all cytokines of the IL-20 subfamily within CNS tissues and specific alteration to IL-20 subfamily cytokines IL-19, IL-20, and IL-24, expression levels. Immunolabeling of CNS region-specific microvessels confirmed IL-20RB protein at the spinal cord microvasculature and upregulation during EAE. Microvessels isolated from macaques CNS tissues also expressed IL-20RB. Moreover, we identified the expression of all IL-20 receptor subunits: IL-22 receptor subunit α-1 (IL-22RA1), IL-20RB, and IL-20 receptor subunit α (IL-20RA) in human CNS microvessels. Notably, human cerebral microvasculature endothelial cells (HCMEC/D3) treated with IL-1β showed augmented expression of the IL-20 receptor. Lastly, IL-20-treated HCMEC/D3 showed alterations on CXCL12 apicobasal polarity consistent with a neuroinflammatory status. This evidence suggests that IL-20 subfamily cytokines may signal at the BBB via IL-20RB, triggering neuroinflammation.

Upregulation of interleukin-19 in severe asthma: a potential saliva biomarker for asthma severity

Interleukin (IL)-19, a designated IL-20 subfamily cytokine, has been implicated in inflammatory disorders including rheumatoid arthritis, psoriasis and, lately, asthma. Here, through the analysis of transcriptomic datasets of lung tissue of large asthma cohorts, we report that IL-19 expression is upregulated in asthma and correlates with disease severity. The gene expression of IL-19 was significantly higher in lung tissue from patients with severe and mild/moderate asthma compared to healthy controls. IL-19 protein level, however, was significantly higher in the blood and saliva of patients with severe asthma compared to mild/moderate subgroups as measured by ELISA assay. IL-19 protein level was not affected by corticosteroid treatment in plasma. Our data provide insights into the potential use of IL-19 as a saliva marker for asthma severity and a potential therapeutic target.

Plasma and saliva IL-19 are significantly upregulated in asthma and correlate with disease severity. Plasma IL-19 is not affected by steroid treatment. This suggests that IL-19 can be used as a biomarker of asthma severity.https://bit.ly/2QfYwpc

Interleukin-20 Acts as a Promotor of Osteoclastogenesis and Orthodontic Tooth Movement

Objectives

Bones constitute organs that are engaged in constant self-remodelling. Osteoblast and osteoclast homeostasis during remodelling contribute to overall skeletal status. Orthodontics is a clinical discipline that involves the investigation and implementation of moving teeth through the bone. The application of mechanical force to the teeth causes an imbalance between osteogenesis and osteogenesis in alveolar bone, leading to tooth movement. Osteoimmunology comprises the crosstalk between the immune and skeletal systems that regulate osteoclast–osteoblast homeostasis. Interleukin- (IL-) 20, an IL-10 family member, is regarded as a proinflammatory factor for autoimmune diseases and has been implicated in bone loss disease. However, the mechanism by which IL-20 regulates osteoclast differentiation and osteoclastogenesis activation remains unclear. This study investigated the effects of IL-20 on osteoclast differentiation in a rat model; it explored the underlying molecular mechanism in vitro and the specific effects on orthodontic tooth movement in vivo.

Methods

For in vitro analyses, primary rat bone marrow-derived macrophages (BMMs) were prepared from Sprague–Dawley rats for osteoclast induction. After BMMs had been treated with combinations of recombinant IL-20 protein, siRNA, and plasmids, the expression levels of osteoclast-specific factors and signalling pathway proteins were detected through real-time polymerase chain reaction, western blotting, and immunofluorescence staining. For in vivo analyses, IL-20 was injected into the rat intraperitoneal cavity after the establishment of a rat orthodontic tooth movement (OTM) model. OTM distance was detected by Micro-CT and HE staining; the expression levels of protein were detected through immunofluorescence staining.

Results

In vitro analyses showed that a low concentration of IL-20 promoted preosteoclast proliferation and osteoclastogenesis. However, a high concentration of IL-20 inhibited BMM proliferation and osteoclastogenesis. IL-20 knockdown decreased the expression of osteoclast specific-markers, while IL-20 overexpression increased the expression of osteoclast specific-markers. Furthermore, IL-20 regulated osteoclast differentiation through the OPG/RANKL/RANK pathway. Overexpression of IL-20 could significantly upregulate RANKL-mediated osteoclast differentiation and osteoclast specific-marker expression; moreover, RANKL/NF-κB/NFATc1 acted as downstream signalling molecule for IL-20. In vivo analysis showed that OTM speed was significantly increased after intraperitoneal injection of IL-20; additionally, mechanical stress sensing proteins were markedly activated.

Conclusions

IL-20 augments osteoclastogenesis and osteoclast-mediated bone erosion through the RANKL/NF-κB/NFATc1 signalling pathway. IL-20 inhibition can effectively reduce osteoclast differentiation and diminish bone resorption. Furthermore, IL-20 can accelerate orthodontic tooth movement and activate mechanical stress sensing proteins.

Interleukins and Interleukin Receptors Evolutionary History and Origin in Relation to CD4+ T Cell Evolution

Understanding the evolution of interleukins and interleukin receptors is essential to control the function of CD4+ T cells in various pathologies. Numerous aspects of CD4+ T cells’ presence are controlled by interleukins including differentiation, proliferation, and plasticity. CD4+ T cells have emerged during the divergence of jawed vertebrates. However, little is known about the evolution of interleukins and their origin. We traced the evolution of interleukins and their receptors from Placozoa to primates. We performed phylogenetic analysis, ancestral reconstruction, HH search, and positive selection analysis. Our results indicated that various interleukins’ emergence predated CD4+ T cells divergence. IL14 was the most ancient interleukin with homologs in fungi. Invertebrates also expressed various interleukins such as IL41 and IL16. Several interleukin receptors also appeared before CD4+ T cells divergence. Interestingly IL17RA and IL17RD, which are known to play a fundamental role in Th17 CD4+ T cells first appeared in mollusks. Furthermore, our investigations showed that there is not any single gene family that could be the parent group of interleukins. We postulate that several groups have diverged from older existing cytokines such as IL4 from TGFβ, IL10 from IFN, and IL28 from BCAM. Interleukin receptors were less divergent than interleukins. We found that IL1R, IL7R might have diverged from a common invertebrate protein that contained TIR domains, conversely, IL2R, IL4R and IL6R might have emerged from a common invertebrate ancestor that possessed a fibronectin domain. IL8R seems to be a GPCR that belongs to the rhodopsin-like family and it has diverged from the Somatostatin group. Interestingly, several interleukins that are known to perform a critical function for CD4+ T cells such as IL6, IL17, and IL1B have gained new functions and evolved under positive selection. Overall evolution of interleukin receptors was not under significant positive selection. Interestingly, eight interleukin families appeared in lampreys, however, only two of them (IL17B, IL17E) evolved under positive selection. This observation indicates that although lampreys have a unique adaptive immune system that lacks CD4+ T cells, they could be utilizing interleukins in homologous mode to that of the vertebrates’ immune system. Overall our study highlights the evolutionary heterogeneity within the interleukins and their receptor superfamilies and thus does not support the theory that interleukins evolved solely in jawed vertebrates to support T cell function. Conversely, some of the members are likely to play conserved functions in the innate immune system.

IL-20R Activation via rIL-19 Enhances Hematoma Resolution through the IL-20R1/ERK/Nrf2 Pathway in an Experimental GMH Rat Pup Model

Aims

Blood clots play the primary role in neurological deficits after germinal matrix hemorrhage (GMH). Previous studies have shown a beneficial effect in blood clot clearance after hemorrhagic stroke. The purpose of this study is to investigate interleukin-19's role in hematoma clearance after GMH and its underlying mechanism of IL-20R1/ERK/Nrf2 signaling pathway.

Methods

A total of 240 Sprague-Dawley P7 rat pups were used. GMH was induced by intraparenchymal injection of bacterial collagenase. rIL-19 was administered intranasally 1 hour post-GMH. IL-20R1 CRISPR was administered intracerebroventricularly, or Nrf2 antagonist ML385 was administered intraperitoneally 48 hours and 1 hour before GMH induction, respectively. Neurobehavior, Western blot, immunohistochemistry, histology, and hemoglobin assay were used to evaluate treatment regiments in the short- and long-term.

Results

Endogenous IL-19, IL-20R1, IL-20R2, and scavenger receptor CD163 were increased after GMH. rIL-19 treatment improved neurological deficits, reduced hematoma volume and hemoglobin content, reduced ventriculomegaly, and attenuated cortical thickness loss. Additionally, treatment increased ERK, Nrf2, and CD163 expression, whereas IL-20R1 CRISPR-knockdown plasmid and ML385 inhibited the effects of rIL-19 on CD163 expression.

Conclusion

rIL-19 treatment improved hematoma clearance and attenuated neurological deficits induced by GMH, which was mediated through the upregulation of the IL-20R1/ERK/Nrf2 pathways. rIL-19 treatment may provide a promising therapeutic strategy for the GMH patient population.

TgROP18 targets IL20RB for host-defense-related-STAT3 activation during Toxoplasma gondii infection

Background

Toxoplasma gondii is an opportunistic protozoan infecting almost one-third of the world’s population. Toxoplasma gondii rhoptry protein 18 (TgROP18) is a key virulence factor determining the parasite’s acute virulence and is secreted into host cells during infection. We previously identified the interaction of TgROP18 and host cell immune-related receptor protein IL20RB, and observed the activation of STAT3 in human keratinocytes (HaCaT) cells infected by the rop16 knockout RH strain, though TgROP16 is regarded as being responsible for host STAT3 activation during T. gondii invasion. Therefore, we hypothesize TgROP18 can activate host STAT3 through binding to IL20RB.

Methods

CRISPR-CAS9 technology was used to generate the ROP16 and ROP18 double knockout RH strain, RH-∆rop16∆rop18. SDS-PAGE and western blot were used to detect STAT3 activation in different HaCaT cells with high endogenous IL20RB expression treated with T. gondii tachyzoites infection, recombinant ROP18, or IL-20. FRET and co-immunoprecipitation (Co-IP) was used to detect the protein-protein interaction.

Results

We observed that TgROP18 was involved in a synergic activation of the host JAK/STAT3 pathway together with TgROP16 in human HaCaT cells infected with T. gondii or treated with recombinant TgROP18 protein, stimulating host proinflammatory immune responses such as expression of TNF-α. The effect of recombinant ROP18 on STAT3 phosphorylation was presented in a dose-dependent manner. Additionally, TgROP18 was identified to target IL20RB on its extracellular domain. When we treated different cell lines with the recombinant ROP18, STAT3 phosphorylation could only be observed in the cells with endogenous IL20RB expression, such as HaCaT cells.

Conclusions

These findings indicate that TgROP18-IL20RB interaction upon T. gondii invasion was involved in STAT3 activation, which is associated with host cell defense.

Characterization of Type-I IFN subtype autoantibodies and activity in SLE serum and urine

BACKGROUND/OBJECTIVE

Type-I interferons contribute to pathogenesis in systemic lupus erythematosus, including nephritis. Interferons consist of a family of 16 proteins yet are often characterized in patients without knowledge of the specific interferon subtypes involved. Different interferons may function in the kidneys, and other organs, relative to what is often measured in patient blood. Moreover, antibodies to interferons may potentially modulate systemic or organ-specific interferon activity. The aim of this study was to characterize global interferon activity levels and identify autoantibodies to the 12 interferon α subtypes in patient serum and urine.

METHODS

Interferon activity levels in serum and urine were measured using an interferon bioassay. Anti-interferon and anti-cytokine autoantibodies were measured by ELISA. Serum and urine samples were also characterized for their ability to neutralize the biological activity of exogenously added interferons.

RESULTS

Serum interferon activity was increased in 62% of systemic lupus erythematosus patient samples, relative to healthy donor controls, whereas binding interferon α autoantibodies to at least one interferon α subtype were found in 68% of the samples evaluated. High Systemic Lupus Erythematosus Disease Activity Index scores were significantly (p = 0.001) associated with patient samples containing interferon α autoantibodies to three or more interferon α subtypes in their serum. Interferon α autoantibodies that potently block interferon activity were rare (∼5% of samples), but collectively bound to all 12 interferon α subtypes. Urine interferon activity and interferon α autoantibody profiles did not correlate with their serum counterparts, suggesting immune responses in systemic lupus erythematosus kidneys can be distinct from those measured in serum. Analysis of autoantibodies to 15 additional cytokines in serum identified higher frequencies of granulocyte-macrophage colony-stimulating factor and interleukin 17A autoantibodies, suggesting these signaling pathways may potentially contribute, with interferons, to systemic lupus erythematosus pathogenesis.

CONCLUSIONS

The measurement of autoantibodies to multiple interferon subtypes in serum and urine may provide an alternative method for following interferon-mediated systemic lupus erythematosus disease activity. The results suggest autoantibodies might be used for patient monitoring and/or identifying additional cytokine signaling pathways that are functioning in different systemic lupus erythematosus patients.

IL-24: A new player in the pathogenesis of pro-inflammatory and allergic skin diseases

Interleukin (IL)-24 is a member of the IL-20 family of cytokines and is produced by various types of cells, such as CD4⁺ T cells, NK cells, mast cells, keratinocytes, bronchial epithelial cells, and myofibroblasts. Previous studies suggest that IL-24 plays an essential role in the pathogenesis of pro-inflammatory autoimmune disorders such as psoriasis, arthritis, and inflammatory bowel diseases. However, the role of IL-24 in the pathogenesis of allergic diseases has been elusive. It has already been reported that IL-24 is involved in the pathogenesis of allergic lung and skin diseases. Moreover, we have recently revealed for the first time the pivotal functions of IL-24 in IL-13-mediated skin barrier dysfunction in atopic dermatitis (AD), which is known to be a characteristic of AD caused by Th2 cytokines such as IL-4 or IL-13. In this review, we show recent advances in the basic characteristics of IL-24 and its novel functions in the pathogenesis of allergic skin inflammation, focusing on AD. A better understanding of the role of IL-24 in allergic diseases can lead to the development of new therapeutic options.

The Evaluation of tLyP-1-Bound Mda-7/IL-24 Killing Activity on a Liver Tumor Cell Line

Introduction: The melanoma differentiation-associated gene-7 (Mda-7)/interleukin-24 (IL-24) is a tumor killing cytokine, the bystander effect of which can be enhanced through tethering to tumor homing peptides (THPs). Materials and Methods: After fusing tLyP-1, RGR, and buforin as THPs to Mda-7/IL-24, enzyme-linked immunosorbent assay (ELISA) was used to determine the secretion potency of the recombinant proteins. The killing potency of plasmids expressing IL-24, IL-24.tLyP1, IL-24.RGR, and buf.IL-24 were assessed, using MTT, Annexin/PI staining assays as well as measuring the expression level of GADD-153 and BCL2-associated X (BAX) on Huh-7 cells. Three-dimensional structural analysis and protein-receptor interaction were also evaluated by modeling. Results: The ELISA result showed that contrary to IL-24.RGR and buf.IL-24, IL-24.tLyP-1 retained the secretion potency, similar to the native form. The viability assessments showed that IL-24 and IL-24.tLyP-1 had the most growth suppressive effects in comparison with the control group (p < 0.0001). Furthermore, IL-24 and IL-24.tLyP-1 had the highest apoptotic activity and significant upregulatory effect on the GADD-153 and BAX genes (p < 0.0003). The modeling showed that peptide modifications left no detrimental effect on IL-24 attachment to the cognate receptor. Conclusion: IL-24 can tolerate tLyP-1 peptide modification by retaining its secretion potency. Tethering tLyP-1 to IL-24 can induce more apoptosis than its modified versions by RGR or buforin.

Characterization of IL-19, -20, and -24 in acute and chronic kidney diseases reveals a pro-fibrotic role of IL-24

BACKGROUND

Recently, the role of IL-19, IL-20 and IL-24 has been reported in renal disorders. However, still little is known about their biological role.

METHODS

Localization of IL-20RB was determined in human biopsies and in the kidneys of mice that underwent unilateral ureteral obstruction (UUO). Renal Il19, Il20 and Il24 expression was determined in ischemia/reperfusion, lipopolysaccharide, streptozotocin, or UUO induced animal models of kidney diseases. The effects of H₂O₂, LPS, TGF-β1, PDGF-B and IL-1β on IL19, IL20 and IL24 expression was determined in peripheral blood mononuclear cells (PBMCs). The extents of extracellular matrix (ECM) and α-SMA, Tgfb1, Pdgfb, and Ctgf expression were determined in the kidneys of Il20rb knockout (KO) and wild type (WT) mice following UUO. The effect of IL-24 was also examined on HK-2 tubular epithelial cells and NRK49F renal fibroblasts.

RESULTS

IL-20RB was present in the renal biopsies of patients with lupus nephritis, IgA and diabetic nephropathy. Amount of IL-20RB increased in the kidneys of mice underwent UUO. The expression of Il19, Il20 and Il24 increased in the animal models of various kidney diseases. IL-1β, H₂O₂ and LPS induced the IL19, IL20 and IL24 expression of PBMCs. The extent of ECM, α-SMA, fibronectin, Tgfb1, Pdgfb, and Ctgf expression was lower in the kidney of Il20rb KO compared to WT mice following UUO. IL-24 treatment induced the apoptosis and TGF-β1, PDGF-B, CTGF expression of HK-2 cells.

CONCLUSIONS

Our data confirmed the significance of IL-19, IL-20 and IL-24 in the pathomechanism of renal diseases. Furthermore, we were the first to demonstrate the pro-fibrotic effect of IL-24.

Role of IL-24 in the mucosal remodeling of children with coeliac disease

BACKGROUND

Recently, involvement of IL-19, IL-20 and IL-24 has been reported in inflammatory diseases associated with tissue remodeling. However, their impact on the pathomechanism of coeliac disease (CD) is still completely unknown.

METHODS

Expression of IL19, IL20 and IL24 was measured by real-time RT-PCR, protein amount of IL-24, α smooth muscle actin (α-SMA) and fibronectin (FN) was determined by Western-blot analysis in the duodenal biopsies of therapy naive children with CD and controls. Localization of IL-24 and IL-20RB was investigated by immunofluorescent staining in the duodenal mucosa. Effect of recombinant IL-1β, TNF-α, TGF-β and IL-17 treatment on the expression of IL19, IL20, IL24 and their receptors was investigated by real-time RT-PCR in small intestinal epithelial cells (FHs74Int), in primary duodenal myofibroblasts (pdMFs) and in peripheral blood mononuclear cells (PBMCs). Effect of IL-24 on H₂O₂ treated FHs74Int cells and on pdMFs was measured by MTT, LDH, Annexin V assays, real-time RT-PCR and by fluorescent microscopy.

RESULTS

We found increased level of IL-24 (3.3×, p < 0.05), α-SMA (2.4×, p < 0.05) and FN (2.3×, p < 0.05) in the duodenal mucosa and increased expression of IL19 (3.6×, p < 0.05) and IL24 (5.2×, p < 0.05) in the PBMCs of children with CD compared to that of controls. IL-1β was a strong inducer of IL24 expression of FHs74Int cells (9.9×, p < 0.05), pdMFs (552.9×, p < 0.05) or PBMCs (17.2×, p < 0.05), as well. IL-24 treatment reduced the number of apoptotic cells (0.5×, p < 0.05) and decreased the expression of inflammatory factors, including IL1A, IL6 and TNF of H₂O₂-treated FHs74Int cells. IL-24 decreased the proliferation (0.6×, p < 0.05) of PDGF-B treated pdMFs. Moreover, IL-24 treatment altered the morphology of pdMFs by influencing the size of the angles between stress fibers and the longitudinal axis of the cells (2.0×, p < 0.05) and the expression of cytoskeletal components, including ACTA2, ACTB, VIM, SNAI1 and SNAI2.

CONCLUSION

Our results suggest that IL-24 plays a significant role in the maintenance of duodenal mucosal integrity in CD.

The molecular details of cytokine signaling via the JAK/STAT pathway

More than 50 cytokines signal via the JAK/STAT pathway to orchestrate hematopoiesis, induce inflammation and control the immune response. Cytokines are secreted glycoproteins that act as intercellular messengers, inducing proliferation, differentiation, growth, or apoptosis of their target cells. They act by binding to specific receptors on the surface of target cells and switching on a phosphotyrosine-based intracellular signaling cascade initiated by kinases then propagated and effected by SH2 domain-containing transcription factors. As cytokine signaling is proliferative and often inflammatory, it is tightly regulated in terms of both amplitude and duration. Here we review molecular details of the cytokine-induced signaling cascade and describe the architectures of the proteins involved, including the receptors, kinases, and transcription factors that initiate and propagate signaling and the regulatory proteins that control it.

Analysis of interleukin-20 receptor complexes in trabecular meshwork cells and effects of cytokine signaling in anterior segment perfusion culture

Purpose

Inflammatory responses may be involved in the glaucomatous process. Our previous studies mapped a T104M mutation in interleukin-20 receptor beta (IL-20RB) in a family with primary open angle glaucoma (POAG). IL-20RB can heterodimerize with IL-20RA to propagate signals from IL-20 family cytokines, IL-19, IL-20, and IL-24 (the type I receptor complex), or it can heterodimerize with IL-22RA to propagate signals from IL-20 and IL-24 (type II receptor complex). In this study, we investigated IL-20 heterodimeric receptor complexes in the trabecular meshwork (TM) compared to dermal fibroblast cell cultures, and examined the phosphorylation of signal transducer and activator of transcription (STAT)-1, -3, and -5 following exposure to IL-20 family cytokines. Additionally, we determined the effects of IL-20 family cytokines on outflow rates in anterior segment perfusion culture, an in vitro model of intraocular pressure (IOP) regulation.

Methods

Primary human TM (HTM) cells were grown from dissected TM tissue, and IL-20 receptor expression was investigated with PCR. A Duolink assay was performed to investigate in situ IL-20 receptor protein interactions in HTM or dermal fibroblasts, and Imaris software was used to quantitate the association of the heterodimeric complexes. Phosphorylation of STAT-1, -3, and -5 were evaluated in HTM or dermal fibroblasts using Western immunoblotting after exposure to IL-10, IL-19, IL-20, IL-22, or IL-24. Anterior segment perfusion culture was performed in human cadaver and porcine eyes treated with IL-20, IL-19, or IL-24.

Results

All of the IL-20 receptors, IL-20RA, IL-20RB, and IL-22RA1 were expressed in HTM cells. Two isoforms of IL-20RA were expressed: The V1 variant, which is the longest, is the predominant isoform, while the V3 isoform, which lacks exon 3, was also expressed. The Duolink assay demonstrated that the type I (IL-20RA-IL-20RB) and type II (IL-22RA1-IL-20RB) receptors were expressed in HTM cells and dermal fibroblasts. However, in the HTM cells, the type I receptor was present at significantly higher levels, while the type II receptor was preferentially used in the dermal fibroblasts. The HTM cells and the dermal fibroblasts predominantly phosphorylate the Ser727 site in STAT-3. The dermal fibroblasts had higher induction of phosphorylated STAT-1 compared to the HTM cells, while neither cell type had phosphorylated STAT-5 in the cell lysates. The outflow rates in the human anterior segment cultures were increased 2.3-fold by IL-20. However, IL-19 and IL-24 showed differential responses. For IL-19 and IL-24, 50% of the eyes responded with a 1.7- or 1.5-fold increase, respectively, while the other half did not respond. Similarly, perfused porcine anterior segments showed "responders" and "non-responders": IL-20 responders (2.3-fold increase in outflow, n=12) and non-responders (n=11); IL-19 responders (2.1-fold increase, n=7) and non-responders (n=5); and IL-24 responders (1.8-fold increase, n=12) and non-responders (n=5).

Conclusions

Type I and type II IL-20 receptor complexes are expressed in human TM cells with predominant expression of the type I receptor (IL-20RA and IL-20RB), which propagates signals from all three IL-20 family cytokines. However, there was a variable response in the outflow rates following perfusion of cytokines in two different species. This may explain why some people are more susceptible to developing elevated IOP in response to inflammation.

Murine astrocytes produce IL-24 and are susceptible to the immunosuppressive effects of this cytokine

BACKGROUND

Glia are key regulators of inflammatory responses within the central nervous system (CNS) following infection or trauma. We have previously demonstrated the ability of activated glia to rapidly produce pro-inflammatory mediators followed by a transition to an anti-inflammatory cytokine production profile that includes the immunosuppressive cytokine interleukin (IL)-10 and the closely related cytokine IL-19. IL-24, another member of the IL-10 family, has been studied in a number of inflammatory conditions in the periphery and is known to modulate immune cell activity. However, the ability of glia to produce IL-24 remains unclear and the effects of this pleiotropic cytokine on glial immune functions have not been investigated.

METHODS

In this study, we have assessed whether primary murine glia produce IL-24 following stimulation and evaluated the effect of this cytokine on the immune responses of such cells. We have utilized RT-PCR and immunoblot analyses to assess the expression of IL-24 and its cognate receptors by astrocytes following challenge with bacteria or their components. Furthermore, we have determined the effect of recombinant IL-24 on astrocyte immune signaling and responses to clinically relevant bacteria using RT-PCR and specific capture ELISAs.

RESULTS

We demonstrate that astrocytes express IL-24 mRNA and release detectable amounts of this cytokine protein in a delayed manner following bacterial challenge. In addition, we have determined that glia constitutively express the cognate receptors for IL-24 and show that such expression can be increased in astrocytes following activation. Importantly, our results indicate that IL-24 exerts an immunosuppressive effect on astrocytes by elevating suppressor of cytokine signaling 3 expression and limiting IL-6 production following challenge. Furthermore, we have demonstrated that IL-24 can also augment the release of IL-10 by bacterially challenged astrocytes and can induce the expression of the potentially neuroprotective mediators, glutamate transporter 1, and cyclooxygenase 2.

CONCLUSIONS

The expression of IL-24 and its cognate receptors by astrocytes following bacterial challenge, and the ability of this cytokine to limit inflammatory responses while promoting the expression of immunosuppressive and/or neuroprotective mediators, raises the intriguing possibility that IL-24 functions to regulate or resolve CNS inflammation following bacterial infection in order to limit neuronal damage.

Interleukin-10 Family Cytokines Immunobiology and Structure

The Interleukin (IL)-10 cytokine family includes IL-10, IL-19, IL-20, IL-22, IL-24, and IL-26, which are considered as Class 2α-helical cytokines. IL-10 is the most important cytokine in suppressing pro-inflammatory responses in all kinds of autoimmune diseases and limiting excessive immune responses. Due to protein structure homology and shared usage of receptor complexes as well as downstream signaling pathway, other IL-10 family cytokines also show indispensable functions in immune regulation, tissue homeostasis, and host defense. In this review, we focus on immune functions and structures of different cytokines in this family and try to better understand how their molecular mechanisms connect to their biological functions. The molecular details regarding their actions also provide useful information in developing candidate immune therapy reagents for a variety of diseases.

The Interleukin-10 Family of Cytokines and Their Role in the CNS

Resident cells of the central nervous system (CNS) play an important role in detecting insults and initiating protective or sometimes detrimental host immunity. At peripheral sites, immune responses follow a biphasic course with the rapid, but transient, production of inflammatory mediators giving way to the delayed release of factors that promote resolution and repair. Within the CNS, it is well known that glial cells contribute to the onset and progression of neuroinflammation, but it is only now becoming apparent that microglia and astrocytes also play an important role in producing and responding to immunosuppressive factors that serve to limit the detrimental effects of such responses. Interleukin-10 (IL-10) is generally considered to be the quintessential immunosuppressive cytokine, and its ability to resolve inflammation and promote wound repair at peripheral sites is well documented. In the present review article, we discuss the evidence for the production of IL-10 by glia, and describe the ability of CNS cells, including microglia and astrocytes, to respond to this suppressive factor. Furthermore, we review the literature for the expression of other members of the IL-10 cytokine family, IL-19, IL-20, IL-22 and IL-24, within the brain, and discuss the evidence of a role for these poorly understood cytokines in the regulation of infectious and sterile neuroinflammation. In concert, the available data indicate that glia can produce IL-10 and the related cytokines IL-19 and IL-24 in a delayed manner, and these cytokines can limit glial inflammatory responses and/or provide protection against CNS insult. However, the roles of other IL-10 family members within the CNS remain unclear, with IL-20 appearing to act as a pro-inflammatory factor, while IL-22 may play a protective role in some instances and a detrimental role in others, perhaps reflecting the pleiotropic nature of this cytokine family. What is clear is that our current understanding of the role of IL-10 and related cytokines within the CNS is limited at best, and further research is required to define the actions of this understudied family in inflammatory brain disorders.

Crystal Structure of the Labile Complex of IL-24 with the Extracellular Domains of IL-22R1 and IL-20R2

Crystal structure of the ternary complex of human IL-24 with two receptors, IL-22R1 and IL-20R2, has been determined at 2.15 Å resolution. A crystallizable complex was created by a novel approach involving fusing the ligand with a flexible linker to the presumed low-affinity receptor, and coexpression of this construct in Drosophila S2 cells together with the presumed high-affinity receptor. This approach, which may be generally applicable to other multiprotein complexes with low-affinity components, was necessitated by the instability of IL-24 expressed by itself in either bacteria or insect cells. Although IL-24 expressed in Escherichia coli was unstable and precipitated almost immediately upon its refolding and purification, a small fraction of IL-24 remaining in the folded state was shown to be active in a cell-based assay. In the crystal structure presented here, we found that two cysteine residues in IL-24 do not form a predicted disulfide bond. Lack of structural restraint by disulfides, present in other related cytokines, is most likely reason for the low stability of IL-24. Although the contact area between IL-24 and IL-22R1 is larger than between the cytokine and IL-20R2, calculations show the latter interaction to be slightly more stable, suggesting that the shared receptor (IL-20R2) might be the higher-affinity receptor.

The IL-20 Cytokine Family in Rheumatoid Arthritis and Spondyloarthritis

This review describes the IL-20 family of cytokines in rheumatoid arthritis (RA) and spondyloartrhitits (SpA) including psoriatic arthritis. The IL-20 receptor (R) cytokines IL-19, IL-20, and IL-24 are produced in both the peripheral blood and the synovial joint and are induced by Toll-like receptor ligands and autoantibody-associated immune complexes in monocytes. IL-19 seems to have anti-inflammatory functions in arthritis. In contrast, IL-20 and IL-24 increase the production of proinflammatory molecules such as monocyte chemoattractant protein 1 and are associated with bone degradation and radiographic progression. IL-22 is also associated with progression of bone erosions. This suggests that the IL-22RA1 subunit shared by IL-20, IL-22, and IL-24 is important for bone homeostasis. In line with this, the IL-22RA1 has been found on preosteoclasts in early RA. IL-26 is produced in high amounts by myofibroblasts and IL-26 stimulation of monocytes is an important inducer of Th17 cells in RA. This indicates a role for IL-26 as an important factor in the interactions between resident synovial cells and infiltrating leukocytes. Clinical trials that investigate inhibitors of IL-20 (fletikumab) and IL-22 (fezakinumab) in psoriasis and RA have been terminated. Instead, it seems that the strategy for modulating the IL-20 cytokine family should take the overlap in cellular sources and effector mechanisms into account. The redundancy encourages inhibition of more than one cytokine or one of the shared receptors. All IL-20 family members utilize the Janus kinase signaling pathway and are therefore potentially inhibited by drugs targeting these enzymes. Effects and adverse effects in ongoing clinical trials with inhibitors of IL-22 and the IL-22RA1 subunit and recombinant IL-22 fusion proteins will possibly provide important information about the IL-20 subfamily of cytokines in the future.

Interferons type II and their receptors R1 and R2 in fish species: Evolution, structure, and function

Interferon gamma (IFN-γ) is one of the key players in the immune system of vertebrates. The evolution and properties of IFN-γ and its receptors in fish species are of special interest as they point to the origin of innate immunity in vertebrates. We studied the phylogeny, biophysical and structural properties of IFN-γ and its receptors. Our phylogeny analysis suggests the existence of two groups of IFN-γ related proteins, one specific for Acanthomorpha, the other for Cypriniformes, Characiformes and Siluriformes. The analysis further shows an ancient duplication of the gene for IFN-γ receptor 1 (IFN- γR1) and the parallel existence of the duplicated genes in all current teleost fish species. In contrast, only one gene can be found for receptor 2, IFN- γR2. The specificity of the interaction between IFN- γ and both types of IFN- γR1 was determined by microscale thermophoresis measurements of the equilibrium dissociation constants for the proteins from three fish species. The measured preference of IFN- γ for one of the two forms of receptor 1agrees with the bioinformatic analysis of the coevolution between IFN- γ and receptor 1. To elucidate structural relationships between IFN-γ of fish and other vertebrate species, we determined the crystal structure of IFN-γ from olive flounder (Paralichthys olivaceus, PoliIFN-γ) at crystallographic resolution of 2.3 Å and the low-resolution structures of Takifugu rubripes, Oreochromis niloticus, and Larimichthys crocea IFN-γ by small angle X-ray diffraction. The overall PoliIFN-γ fold is the same as the fold of the other known IFN- γ structures but there are some significant structural differences, namely the additional C-terminal helix G and a different angle between helices C and D in PoliIFN-γ.

Comparison of monocyte gene expression among patients with neurocysticercosis-associated epilepsy, Idiopathic Epilepsy and idiopathic headaches in India

Background

Neurocysticercosis (NCC), a neglected tropical disease, inflicts substantial health and economic costs on people living in endemic areas such as India. Nevertheless, accurate diagnosis using brain imaging remains poorly accessible and too costly in endemic countries. The goal of this study was to test if blood monocyte gene expression could distinguish patients with NCC-associated epilepsy, from NCC-negative imaging lesion-free patients presenting with idiopathic epilepsy or idiopathic headaches.

Methods/Principal findings

Patients aged 18 to 51 were recruited from the Department of Neurological Sciences, Christian Medical College and Hospital, Vellore, India, between January 2013 and October 2014. mRNA from CD14+ blood monocytes was isolated from 76 patients with NCC, 10 Recovered NCC (RNCC), 29 idiopathic epilepsy and 17 idiopathic headaches patients. A preliminary microarray analysis was performed on six NCC, six idiopathic epilepsy and four idiopathic headaches patients to identify genes differentially expressed in NCC-associated epilepsy compared with other groups. This analysis identified 1411 upregulated and 733 downregulated genes in patients with NCC compared to Idiopathic Epilepsy. Fifteen genes up-regulated in NCC patients compared with other groups were selected based on possible relevance to NCC, and analyzed by qPCR in all patients’ samples. Differential gene expression among patients was assessed using linear regression models. qPCR analysis of 15 selected genes showed generally higher gene expression among NCC patients, followed by RNCC, idiopathic headaches and Idiopathic Epilepsy. Gene expression was also generally higher among NCC patients with single cyst granulomas, followed by mixed lesions and single calcifications.

Conclusions/Significance

Expression of certain genes in blood monocytes can distinguish patients with NCC-related epilepsy from patients with active Idiopathic Epilepsy and idiopathic headaches. These findings are significant because they may lead to the development of new tools to screen for and monitor NCC patients without brain imaging.

Taenia solium is a parasite normally transmitted between humans and pigs in areas with poor sanitation. Neurocysticercosis (NCC) occurs when humans are infected with larvae of T. solium that are shed with human feces and the larvae establish in the brain. NCC is often accompanied by neurological symptoms such as epilepsy. In fact, NCC causes approximately one-third of epilepsy cases in areas where T. solium is common. Unfortunately, diagnosis of NCC requires brain computerized tomography or magnetic resonance imaging, tools rarely accessible to people living where NCC is prevalent. This study tested whether genes expressed in blood monocytes, a type of white blood cell, could distinguish between people with epilepsy caused by NCC from those with epilepsy of unknown cause (idiopathic). We compared gene expression in people with NCC and epilepsy, people with idiopathic epilepsy, people cured of NCC and people without NCC or epilepsy but with headaches. We identified 15 genes which were expressed differently in the four different groups indicating that monocyte gene expression patterns in people with NCC and epilepsy are different than people with idiopathic epilepsy. These findings could lead to better understanding how humans respond to NCC and to diagnostic tests which would not require brain imaging.

Increased interleukin (IL)-20 and IL-24 target osteoblasts and synovial monocytes in spondyloarthritis

The pathogenesis of spondyloarthritis (SpA) involves activation of the innate immune system, inflammation and new bone formation. The two cytokines interleukin (IL)-20 and IL-24 have been shown to link innate immune activation and tissue homeostasis. We hypothesized that these two cytokines are secreted as part of activation of the innate immune system and affect bone homeostasis in SpA. IL-20 and IL-24 were measured in plasma from axial SpA patients (n = 83). Peripheral SpA patients (n = 16) were included for in-vitro cell culture studies. The plasma IL-20 and IL-24 levels were increased in SpA patients compared with healthy controls (HCs) by 57 and 83%, respectively (both P < 0·0001). The Toll-like receptor 4-induced secretion of the two cytokines was greater in SpA peripheral blood mononuclear cells (PBMCs) compared with HC PBMCs. IL-20 and IL-24 increased the production of monocyte chemoattractant protein-1 by activated SpA synovial fluid monocytes, decreased the production of Dickkopf-1 by SpA fibroblast-like synovial cells and induced mineralization in human osteoblasts. Taken together, our findings indicate disease-aggravating functions of IL-20 and IL-24 in SpA.

A Broad Blockade of Signaling from the IL-20 Family of Cytokines Potently Attenuates Collagen-Induced Arthritis

Two heterodimeric receptors consisting of either IL-20R1 or IL-22R1 in complex with a common β receptor subunit IL-20R2 are shared by three of the IL-20 family of cytokines: IL-19, IL-20, and IL-24. These proinflammatory cytokines have been implicated in the pathogenesis of some autoimmune diseases, including rheumatoid arthritis (RA), psoriasis, and atopic dermatitis. Although mAbs against IL-19 and IL-20 have each been shown to modulate disease severity of collagen-induced arthritis in animal models, and anti-IL-20 therapeutic Ab has exhibited some efficacy in the treatment of RA in clinical trials, benefits for a complete blockade of these functionally redundant cytokines remain to be explored. In this report, we show that recombinant human soluble IL-20R2-Fc fusion protein binds to IL-19, IL-20, and IL-24 with similar high affinity and blocks their signaling in vitro. In DBA/1 mouse collagen-induced arthritis model, recombinant human IL-20R2-Fc exhibits comparable efficacy as TNF blocker etanercept in the treatment of established arthritis, whereas the combined use of both biologics manifests little synergistic therapeutic effects. In situ ligand-receptor functional binding analysis shows that a large amount of immune infiltrates expressing high levels of TNFR and IL-20 subfamily cytokines congregate within the inflamed disease tissues. Colocalization experiments reveal that signals from IL-20R2 and TNF transduction pathways seem to converge in macrophages and function in tandem in orchestrating the pathogenesis of RA. Elucidation of this interaction provides a better understanding of cytokine cross-talk in RA and a rationale for more effective biologic therapies that target IL-20R2 instead of individual cytokines from IL-20 family.

Crystal structure of human interferon-γ receptor 2 reveals the structural basis for receptor specificity

Interferon-γ receptor 2 is a cell-surface receptor that is required for interferon-γ signalling and therefore plays a critical immunoregulatory role in innate and adaptive immunity against viral and also bacterial and protozoal infections. A crystal structure of the extracellular part of human interferon-γ receptor 2 (IFNγR2) was solved by molecular replacement at 1.8 Å resolution. Similar to other class 2 receptors, IFNγR2 has two fibronectin type III domains. The characteristic structural features of IFNγR2 are concentrated in its N-terminal domain: an extensive π-cation motif of stacked residues KWRWRH, a NAG-W-NAG sandwich (where NAG stands for N-acetyl-D-glucosamine) and finally a helix formed by residues 78-85, which is unique among class 2 receptors. Mass spectrometry and mutational analyses showed the importance of N-linked glycosylation to the stability of the protein and confirmed the presence of two disulfide bonds. Structure-based bioinformatic analysis revealed independent evolutionary behaviour of both receptor domains and, together with multiple sequence alignment, identified putative binding sites for interferon-γ and receptor 1, the ligands of IFNγR2.

Impact of RGD Peptide Tethering to IL24/mda-7 (Melanoma Differentiation Associated Gene-7) on Apoptosis Induction in Hepatocellular Carcinoma Cells

BACKGROUND

Melanoma differentiation-associated gene-7 (MDA-7)/interleukin-24 (IL-24), a unique tumor suppressor gene, has killing activity in a broad spectrum of cancer cells. Herein, plasmids producing mda-7 proteins fused to different RGD peptides (full RGD4C and shortened RGD, tRGD) were evaluated for apoptosis induction with a hepatocellular carcinoma cell line, Hep-G2. The study aim was to improve the apoptosis potency of mda-7 by tethering to RGD peptides.

MATERIALS AND METHODS

Three plasmids including mda-7, mda-7-RGD and mda-7-tRGD genes beside a control vector were transfected into Hep-G2 cells. After 72 hours incubation, cell viability was evaluated by MTT assay. In addition, the rate of apoptosis was analyzed by flow cytometry using PI/annexin staining. To detect early events in apoptosis, 18 hours after transfection, expression of the BAX gene was quantified by real time PCR. Modeling of proteins was also performed to extrapolate possible consequences of RGD modification on their structures and subsequent attachment to receptors.

RESULTS AND CONCLUSIONS

In MTT assays, while all mda-7 forms showed measurable inhibition of proliferation, unmodified mda-7 protein exhibited most significant effect compared to control plasmid (P<0.001). Again, flow cytometry analysis showed a significant apoptosis induction by simple mda-7 gene but not for those RGD-fused mda-7 proteins. These findings were also supported by expression analysis of BAX gene (P<0.001). Protein modelling analysis revealed that tethering RGD at the end of IL-24/Mda7 disrupt attachment to cognate receptor, IL-20R1/ IL-20R2. In conclusion, fusion of RGD4C and shortened RGD peptides to carboxyl terminal of mda7, not only reduce apoptosis property in vitro but also disrupt receptor attachment as demonstrated by protein modelling.

Identification of the Glycosaminoglycan Binding Site of Interleukin-10 by NMR Spectroscopy

The biological function of interleukin-10 (IL-10), a pleiotropic cytokine with an essential role in inflammatory processes, is known to be affected by glycosaminoglycans (GAGs). GAGs are highly negatively charged polysaccharides and integral components of the extracellular matrix with important functions in the biology of many growth factors and cytokines. The molecular mechanism of the IL-10/GAG interaction is unclear. In particular, experimental evidence about IL-10/GAG binding sites is lacking, despite its importance for understanding the biological role of the interaction. Here, we report the experimental determination of a GAG binding site of IL-10. Although no co-crystal structure of the IL-10·GAG complex could be obtained, its structural characterization was possible by NMR spectroscopy. Chemical shift perturbations of IL-10 induced by GAG binding were used to narrow down the location of the binding site and to assess the affinity for different GAG molecules. Subsequent observation of NMR pseudocontact shifts of IL-10 and its heparin ligand, as induced by a protein-attached lanthanide spin label, provided structural restraints for the protein·ligand complex. Using these restraints, pseudocontact shift-based rigid body docking together with molecular dynamics simulations yielded a GAG binding model. The heparin binding site is located at the C-terminal end of helix D and the adjacent DE loop and coincides with a patch of positively charged residues involving arginines 102, 104, 106, and 107 and lysines 117 and 119. This study represents the first experimental characterization of the IL-10·GAG complex structure and provides the starting point for revealing the biological significance of the interaction of IL-10 with GAGs.

Interleukin 20 regulates dendritic cell migration and expression of co-stimulatory molecules

Background

Psoriasis is an inflammatory disease characterized by leukocyte skin infiltration. Interestingly, recent works suggest that the migration of dendritic cells (DCs) is abnormal in psoriatic skin. DCs have significant role in regulating the function of T lymphocytes, at least in part influenced by the local environment of cytokines. In psoriatic skin lesions the expression of IL-20 is highly up-regulated. It is unclear if this cytokine has any influence on DCs.

Methods

Here, we investigated the influence of IL-20 in monocyte-derived dendritic cell (MDDCs) in vitro. This work addressed IL-20 effects on DC maturation, receptor expression and signaling. By use of extra cellular matrix components mimicking the skin environment, we also studied the functional effects of IL-20 on the chemotactic migration of DCs. Based on the recent finding that CD18 integrin are shed during migration of myeloid leukocytes, the concentration of these adhesion molecules was measured in MDDCs culture supernatants post migration.

Results

Following stimulation with IL-20, immature human MDDCs enhanced the expression of the co-stimulatory molecule CD86, further enabling activation of the p38 MAPK, but not the STAT3, pathway. IL-20 increased the migration of MDDCs in a biphasic response narrowly controlled by the interleukin concentration. A concomitant change in the shedding of CD18 integrins suggested that these adhesion molecules play a role in the migration of the MDDCs through the extracellular matrix layer.

Conclusion

Taken together, our findings points to a possible, yet subtle, role of IL-20 in DCs migration. The biphasic response suggests that the aberrant IL-20 expression in psoriasis impedes DC migration, which could be a part of the processes that precipitates the dysregulated inflammatory response associated with this disease.

Electronic supplementary material

The online version of this article (doi:10.1186/s40591-016-0046-x) contains supplementary material, which is available to authorized users.

Interleukin 20 regulates dendritic cell migration and expression of co-stimulatory molecules

BACKGROUND

Psoriasis is an inflammatory disease characterized by leukocyte skin infiltration. Interestingly, recent works suggest that the migration of dendritic cells (DCs) is abnormal in psoriatic skin. DCs have significant role in regulating the function of T lymphocytes, at least in part influenced by the local environment of cytokines. In psoriatic skin lesions the expression of IL-20 is highly up-regulated. It is unclear if this cytokine has any influence on DCs.

METHODS

Here, we investigated the influence of IL-20 in monocyte-derived dendritic cell (MDDCs) in vitro. This work addressed IL-20 effects on DC maturation, receptor expression and signaling. By use of extra cellular matrix components mimicking the skin environment, we also studied the functional effects of IL-20 on the chemotactic migration of DCs. Based on the recent finding that CD18 integrin are shed during migration of myeloid leukocytes, the concentration of these adhesion molecules was measured in MDDCs culture supernatants post migration.

RESULTS

Following stimulation with IL-20, immature human MDDCs enhanced the expression of the co-stimulatory molecule CD86, further enabling activation of the p38 MAPK, but not the STAT3, pathway. IL-20 increased the migration of MDDCs in a biphasic response narrowly controlled by the interleukin concentration. A concomitant change in the shedding of CD18 integrins suggested that these adhesion molecules play a role in the migration of the MDDCs through the extracellular matrix layer.

CONCLUSION

Taken together, our findings points to a possible, yet subtle, role of IL-20 in DCs migration. The biphasic response suggests that the aberrant IL-20 expression in psoriasis impedes DC migration, which could be a part of the processes that precipitates the dysregulated inflammatory response associated with this disease.

The Role of the IL-20 Subfamily in Glaucoma

Glaucoma is a common disease that leads to loss of peripheral vision and, if left untreated, ultimately to blindness. While the exact cause(s) of glaucoma is still unknown, two leading risk factors are age and elevated intraocular pressure. Several studies suggest a possible link between glaucoma and inflammation in humans and animal models. In particular, our lab recently identified a T104M mutation in IL-20 receptor-B (IL-20RB) in primary open angle glaucoma patients from a large pedigree. Several of the interleukin- (IL-) 20 family of cytokines and receptors are expressed in ocular tissues including the trabecular meshwork, optic nerve head, and retinal ganglion cells. The DBA/2J mouse develops high intraocular pressures with age and has characteristic optic nerve defects that make it a useful glaucoma model. IL-24 expression is significantly upregulated in the retina of these mice, while IL-20RA expression in the optic nerve is downregulated following pressure-induced damage. The identification of a mutation in the IL-20RB gene in a glaucoma pedigree and changes in expression levels of IL-20 family members in the DBA/2J mouse suggest that disruption of normal IL-20 signaling in the eye may contribute to degenerative processes associated with glaucoma.