SOCS-1 binding to tyrosine 441 of IFN-gamma receptor subunit 1 contributes to the attenuation of IFN-gamma signaling in vivo

Elevated NS1 serum levels reduce CD119 expression and CXCL-10 synthesis in patients with dengue hemorrhagic fever

BACKGROUND

The intensity of dengue virus (DV) replication and circulating non-structural protein 1 (NS1) levels may promote changes in the human immune response and favor severe forms of infection. We investigated the correlations between NS1 with CXCL-8, CXCL-10, IFN-γ, and IL-12p40 serum levels, and IFN-γ receptor α chain (CD119) expression, and CXCL10 production by peripheral blood mononuclear cells (PBMCs) stimulated with recombinant IFN-γ in DV-infected patients with different clinical forms.

METHODS

Dengue virus NS1, CXCL-8, CXCL-10, IFN-γ, and IL-12p40 serum levels were measured in 152 DV-infected patients with different clinical forms and 20 non-infected individuals (NI) using enzyme-linked immunosorbent assay (ELISA). In addition, we investigated the CXCL-10 production after in vitro IFN-γ stimulation of PBMCs from 48 DV-infected individuals (with different clinical forms of dengue fever) and 20 NI individuals using ELISA, and CD119 expression on CD14+ cells with flow cytometry.

RESULTS

Patients with dengue hemorrhagic fever (DHF) had significantly higher NS1, CXCL-8, and CXCL-10 serum levels than those with classic dengue fever (DF). The response of PBMCs to IFN-γ stimulation was lower in patients with DHF than in those with DF or dengue with complications (DWC), with lower CD119 expression and reduced CXCL-10 synthesis. In addition, these alterations are associated with high NS1 serum levels.

CONCLUSIONS

Patients with DHF reported high NS1 levels, low CD119 expression, and low CXCL-10 synthesis in PBMCs, which may be associated with infection progression and severity.

Suppressor of Cytokine Signaling 1 Haploinsufficiency: A New Driver of Autoimmunity and Immunodysregulation

Suppressor of cytokine signaling 1 (SOCS1) is a negative regulator of cytokine signaling that inhibits the activation of Janus kinases. A human disease caused by SOCS1 haploinsufficiency was first identified in 2020. To date, 18 cases of SOCS1 haploinsufficiency have been described. These patients experience enhanced activation of leukocytes and multiorgan system immunodysregulation, with immune-mediated cytopenia as the most common feature. In this review, the authors provide an overview on the biology of SOCS1 and summarize their knowledge of SOCS1 haploinsufficiency including genetics and clinical manifestations. They discuss the available treatment experience and outline an approach for the evaluation of suspected cases.

Insights on TAM Formation from a Boolean Model of Macrophage Polarization Based on In Vitro Studies

Simple Summary

The recent success of immunotherapy treatments against cancer relies on helping our own body’s defenses in the fight against tumours, namely reinvigorating the cancer killing action of T cells. Unfortunately, in a large proportion of patients these therapies are ineffective, in part due to the presence of other immune cells, macrophages, which are mis-educated by the cancer cells into promoting tumour growth. Here we start from an existing model of macrophage polarization and extend it to the specific conditions encountered inside a tumour by adding signals, receptors, transcription factors and cytokines that are known to be the key components in establishing the cancer cell-macrophage interaction. Then we use a mathematical Boolean model applied to a gene regulatory network of this biological process to simulate its temporal behaviour and explore scenarios that have not been experimentally tested so far. Additionally, the KO and overexpression simulations successfully reproduce the known experimental results while predicting the potential role of regulators (such as STAT1 and EGF) in preventing the formation of pro-tumoural macrophages, which can be tested experimentally.

Abstract

The tumour microenvironment is the surrounding of a tumour, including blood vessels, fibroblasts, signaling molecules, the extracellular matrix and immune cells, especially neutrophils and monocyte-derived macrophages. In a tumour setting, macrophages encompass a spectrum between a tumour-suppressive (M1) or tumour-promoting (M2) state. The biology of macrophages found in tumours (Tumour Associated Macrophages) remains unclear, but understanding their impact on tumour progression is highly important. In this paper, we perform a comprehensive analysis of a macrophage polarization network, following two lines of enquiry: (i) we reconstruct the macrophage polarization network based on literature, extending it to include important stimuli in a tumour setting, and (ii) we build a dynamical model able to reproduce macrophage polarization in the presence of different stimuli, including the contact with cancer cells. Our simulations recapitulate the documented macrophage phenotypes and their dependencies on specific receptors and transcription factors, while also unravelling the formation of a special type of tumour associated macrophages in an in vitro model of chronic lymphocytic leukaemia. This model constitutes the first step towards elucidating the cross-talk between immune and cancer cells inside tumours, with the ultimate goal of identifying new therapeutic targets that could control the formation of tumour associated macrophages in patients.

Chemotherapy followed by anti-CD137 mAb immunotherapy improves disease control in a mouse myeloma model

Immunotherapy holds promise for multiple myeloma (MM) patients but little is known about how MM-induced immunosuppression influences response to therapy. Here, we investigated the impact of disease progression on immunotherapy efficacy in the Vk*MYC mouse model. Treatment with agonistic anti-CD137 (4-1BB) mAbs efficiently protected mice when administered early but failed to contain MM growth when delayed more than three weeks after Vk*MYC tumor cell challenge. The quality of CD8+ T cell response to CD137 stimulation was not altered by the presence of MM, but CD8+ T cell numbers were profoundly reduced at the time of treatment. Our data suggest that an insufficient ratio of CD8+ T cells over MM cells (CD8/MM) accounts for the loss of anti-CD137 mAb efficacy. We established serum M-protein levels prior to therapy as a predictive factor of response. Moreover, we developed an in silico model to capture the dynamic interactions between CD8+ T cells and MM cells. Finally, we explored two methods to improve the CD8/MM ratio: anti-CD137 mAb immunotherapy combined with Treg-depletion or administered after chemotherapy treatment with cyclophosphamide or melphalan efficiently reduced MM burden and prolonged survival. Altogether, our data indicate that consolidation treatment with anti-CD137 mAbs might prevent MM relapse.

IL-11 prevents IFN-γ-induced hepatocyte death through selective downregulation of IFN-γ/STAT1 signaling and ROS scavenging

Aims

Interferon-γ (IFN-γ) exhibits hepatotoxicity through signal transducer and activator of transcription 1 (STAT1) activation. On the contrary, interleukin-11 (IL-11) shows tissue-protective effects on various organs including the liver through STAT3 activation. Here, we found that IL-11 pretreatment protects hepatocytes from IFN-γ-induced death and investigated the molecular mechanisms, particularly focusing on signal crosstalk.

Methods and results

Primary culture mouse hepatocytes were treated with IL-11 prior to IFN-γ, and cell death was evaluated by lactate dehydrogenase release into media. As a result, IL-11 pretreatment effectively suppressed IFN-γ-induced hepatocyte death. Since IFN-γ-induced hepatocyte death requires STAT1 signaling, the activity of STAT1 was analyzed. IFN-γ robustly activated STAT1 with its peak at 1 hr after stimulation, which was significantly attenuated by IL-11 pretreatment. Consistently, IL-11 pretreatment impeded mRNA increase of STAT1-downstream molecules promoting cell death, i.e., IRF-1, caspase 1, bak, and bax. IL-11-mediated suppression of STAT1 signaling was presumably due to upregulation of the suppressor of cytokine signaling (SOCS) genes, which are well-known negative feedback regulators of the JAK/STAT pathway. Interestingly, however, IFN-γ pretreatment failed to affect the following IL-11-induced STAT3 activation, although IFN-γ also upregulated SOCSs. Finally, we demonstrated that IL-11 pretreatment mitigated oxidative stress through increasing expression of ROS scavengers.

Conclusion

IL-11 protects hepatocytes from IFN-γ-induced death via STAT1 signal suppression and ROS scavenging. Further investigation into the mechanisms underlying selective negative feedback regulation of IFN-γ/STAT1 signaling compared to IL-11/STAT3 signaling may shed new light on the molecular biology of hepatocytes.

Understanding SOCS protein specificity

The development and activity of our immune system are largely controlled by the action of pleiotropic cytokines and growth factors, small secreted proteins, which bind to receptors on the surface of immune cells to initiate an appropriate physiological response. Cytokine signalling is predominantly executed by intracellular proteins known as the Janus kinases (JAKs) and the signal transducers and activators of transcriptions (STATs). Although the 'nuts and bolts' of cytokine-activated pathways have been well established, the nuanced way in which distinct cellular outcomes are achieved and the precise molecular details of the proteins that regulate these pathways are still being elucidated. This is highlighted by the intricate role of the suppressor of cytokine signalling (SOCS) proteins. The SOCS proteins act as negative feedback inhibitors, dampening specific cytokine signals to prevent excessive cellular responses and returning the cell to a homeostatic state. A great deal of study has demonstrated their ability to inhibit these pathways at the receptor complex, either through direct inhibition of JAK activity or by targeting the receptor complex for proteasomal degradation. Detailed analysis of individual SOCS proteins is slowly revealing the complex and highly controlled manner by which they can achieve specificity for distinct substrates. However, for many of the SOCS, a level of detail is still lacking, including confident identification of the full suite of tyrosine phosphorylated targets of their SH2 domain. This review will highlight the general mechanisms which govern SOCS specificity of action and discuss the similarities and differences between selected SOCS proteins, focusing on CIS, SOCS1 and SOCS3. Because of the functional and sequence similarities within the SOCS family, we will also discuss the evidence for functional redundancy.

Galectin-3 captures interferon-gamma in the tumor matrix reducing chemokine gradient production and T-cell tumor infiltration

The presence of T cells in tumors predicts overall survival for cancer patients. However, why most tumors are poorly infiltrated by T cells is barely understood. T-cell recruitment towards the tumor requires a chemokine gradient of the critical IFNγ-induced chemokines CXCL9/10/11. Here, we describe how tumors can abolish IFNγ-induced chemokines, thereby reducing T-cell attraction. This mechanism requires extracellular galectin-3, a lectin secreted by tumors. Galectins bind the glycans of glycoproteins and form lattices by oligomerization. We demonstrate that galectin-3 binds the glycans of the extracellular matrix and those decorating IFNγ. In mice bearing human tumors, galectin-3 reduces IFNγ diffusion through the tumor matrix. Galectin antagonists increase intratumoral IFNγ diffusion, CXCL9 gradient and tumor recruitment of adoptively transferred human CD8⁺ T cells specific for a tumor antigen. Transfer of T cells reduces tumor growth only if galectin antagonists are injected. Considering that most human cytokines are glycosylated, galectin secretion could be a general strategy for tumor immune evasion.

Most tumours are poorly infiltrated by T cells. Here the authors show that galectin-3 secreted by tumours binds both glycosylated IFNγ and glycoproteins of the tumour extracellular matrix, thus avoiding IFNγ diffusion and the formation of an IFNγ-induced chemokine gradient required for T cell infiltration.

Transcriptional Regulation of Antiviral Interferon-Stimulated Genes

Interferon-stimulated genes (ISGs) are a group of gene products that coordinately combat pathogen invasions, in particular viral infections. Transcription of ISGs occurs rapidly upon pathogen invasion, and this is classically provoked via activation of the Janus kinase/signal transducer and activator of transcription (JAK–STAT) pathway, mainly by interferons (IFNs). However, a plethora of recent studies have reported a variety of non-canonical mechanisms regulating ISG transcription. These new studies are extremely important for understanding the quantitative and temporal differences in ISG transcription under specific circumstances. Because these canonical and non-canonical regulatory mechanisms are essential for defining the nature of host defense and associated detrimental proinflammatory effects, we comprehensively review the state of this rapidly evolving field and the clinical implications of recently acquired knowledge in this respect.

Transcriptional regulation of ISGs defines the state of host anti-pathogen defense.

In light of the recently identified regulatory elements and mechanisms of the IFN–JAK–STAT pathway, new insights have been gained into this classical cascade in regulating ISG transcription.

A variety of non-canonical mechanisms have been recently revealed that coordinately regulate ISG transcription.

With regards to the adverse effects of IFNs in clinic, ISG-based antiviral strategy could be the next promising frontier in drug discovery.

Dual Faces of IFNγ in Cancer Progression: A Role of PD-L1 Induction in the Determination of Pro- and Antitumor Immunity

IFNγ is a cytokine that plays a pivotal role in antitumor host immunity. IFNγ elicits potent antitumor immunity by inducing Th1 polarization, CTL activation, and dendritic cell tumoricidal activity. However, there are significant discrepancies in our understanding of the role of IFNγ as an antitumor cytokine. In certain circumstances, IFNγ obviously acts to induce tumor progression. IFNγ treatment has negatively affected patient outcomes in some clinical trials, while it has favorably affected outcomes in other trials. Several mechanisms, including IFNγ insensitivity and the downregulation of the MHC complex, have been regarded as the reasons for this discrepancy, but they do not fully explain it. We propose IFNγ-induced programmed cell death 1 ligand 1 (PD-L1) expression as a novel mechanism by which IFNγ impairs tumor immunity. When tumor cells encounter CTLs in the local environment, they detect them via the high concentration of IFNγ secreted from CTLs, which induces PD-L1 expression in preparation for an immune attack. Thus, tumor cells acquire the capability to counterattack immune cells. These findings indicate that although IFNγ is thought to be a representative antitumor cytokine, it actually has dual roles: one as a hallmark of antitumor immunity and the other as an inducer of the immune escape phenomenon through various mechanisms, such as PD-L1 expression. In this context, the optimization of immunotherapy according to the local immune environment is important. Anti-PD-1/PD-L1 treatment may be particularly promising when efficient tumor immunity is present, but it is disturbed by PD-L1 expression. Clin Cancer Res; 22(10); 2329-34. ©2016 AACR.

Interferons and their stimulated genes in the tumor microenvironment

Constitutive expression of interferons (IFNs) and activation of their signaling pathways have pivotal roles in host responses to malignant cells in the tumor microenvironment. IFNs are induced by the innate immune system and in tumors through stimulation of Toll-like receptors (TLRs) and through other signaling pathways in response to specific cytokines. Although in the oncologic context IFNs have been thought of more as exogenous pharmaceuticals, the autocrine and paracrine actions of endogenous IFNs probably have even more critical effects on neoplastic disease outcomes. Through high-affinity cell surface receptors, IFNs modulate transcriptional signaling, leading to regulation of more than 2,000 genes with varying patterns of temporal expression. Induction of the gene products by both unphosphorylated and phosphorylated STAT1 after ligand binding results in alterations in tumor cell survival, inhibition of angiogenesis, and augmentation of actions of T, natural killer (NK), and dendritic cells. The interferon-stimulated gene (ISG) signature can be a favorable biomarker of immune response but, in a seemingly paradoxical finding, a specific subset of the full ISG signature indicates an unfavorable response to DNA-damaging interventions such as radiation. IFNs in the tumor microenvironment thus can alter the emergence, progression, and regression of malignancies.

SOCS, inflammation, and cancer

Signal transduction pathways elicited by cytokines and hormones have been shown to regulate distinct stages of development. Suppressor of cytokine signaling (SOCS) proteins are negative feedback regulators of cytokine signaling mediated by the JAK-STAT signaling pathway. In particular, SOCS1 and SOCS3 are potent inhibitors of JAKs and can play pivotal roles in inflammation, as well as in the development and progression of cancers. Abnormal expression of SOCS1 and SOCS3 in cancer cells has been reported in human carcinoma associated with dysregulation of signals from cytokine receptors, Toll-like receptors (TLRs), and hormone receptors, resulting in malignancies. In this review, we focus on the role of SOCS1 and SOCS3 in cancer development. In addition, the potential of SOCS as a therapeutic target and diagnostic aid will be discussed.

Suppression of cytokine signaling: the SOCS perspective

The discovery of the Suppressor of Cytokine Signaling (SOCS) family of proteins has resulted in a significant body of research dedicated to dissecting their biological functions and the molecular mechanisms by which they achieve potent and specific inhibition of cytokine and growth factor signaling. The Australian contribution to this field has been substantial, with the initial discovery of SOCS1 by Hilton, Starr and colleagues (discovered concurrently by two other groups) and the following work, providing a new perspective on the regulation of JAK/STAT signaling. In this review, we reflect on the critical discoveries that have lead to our current understanding of how SOCS proteins function and discuss what we see as important questions for future research.

Detection of endogenous SOCS1 and SOCS3 proteins by immunoprecipitation and Western blot analysis

The suppressors of cytokine signalling (SOCS) protein family consist of eight members (SOCS 1-7, and CIS). SOCS1 and SOCS3 are the best-studied family members and have been shown to act as negative feedback inhibitors of the JAK/STAT signalling pathway. To study the physiological roles of the SOCS proteins, it is necessary to establish methods for detecting endogenous proteins often expressed at low levels in cells after cytokine induction. To facilitate the detection of endogenous SOCS1 and SOCS3 proteins, we have generated in-house antibodies specific to these proteins, which we have used together with commercially available antibodies. Here, we describe the methods for immunoprecipitating SOCS1 and SOCS3 proteins from mouse tissue extracts and their subsequent detection by Western blot analysis. These methods can also be applied to the detection of SOCS1 and SOCS3 in cell lines.

Suppression of cytokine signaling by SOCS3: characterization of the mode of inhibition and the basis of its specificity

Janus kinases (JAKs) are key effectors in controlling immune responses and maintaining hematopoiesis. SOCS3 (suppressor of cytokine signaling-3) is a major regulator of JAK signaling and here we investigate the molecular basis of its mechanism of action. We found that SOCS3 bound and directly inhibited the catalytic domains of JAK1, JAK2, and TYK2 but not JAK3 via an evolutionarily conserved motif unique to JAKs. Mutation of this motif led to the formation of an active kinase that could not be inhibited by SOCS3. Surprisingly, we found that SOCS3 simultaneously bound JAK and the cytokine receptor to which it is attached, revealing how specificity is generated in SOCS action and explaining why SOCS3 inhibits only a subset of cytokines. Importantly, SOCS3 inhibited JAKs via a noncompetitive mechanism, making it a template for the development of specific and effective inhibitors to treat JAK-based immune and proliferative diseases.

Role of SOCS1 in tumor progression and therapeutic application

SOCS1, a prototype molecule of the SOCS family, was initially defined as a suppressor of cytokine signaling. The molecular mechanisms of SOCS1-mediated functions have been subsequently identified by studies using gene knockout mice and gene silencing technology. As part of a negative feedback regulation, SOCS1 downregulates cytokine signaling through direct inhibition of the JAK tyrosine kinase and the signaling cascade of activated cytokine receptors, thereby attenuating cytokine-initiated signal transduction. Moreover, other studies have demonstrated that SOCS1 also downregulates TLR signaling through direct and indirect mechanisms. Both cytokine receptor and TLR signaling pathways mediate important functions in survival, maturation and differentiation of various types of cells and in the regulation of immune function. Abnormal expression of SOCS1 in tumor cells has been detected in various human cancers, where it is associated with dysregulation of cytokine receptor and TLR signaling to promote cell transformation. Recent studies on the function of SOCS1 in tumor cells have revealed its novel role in carcinogenesis. In this review, we will focus on the mechanism of action of SOCS1 in both tumor cells and antigen-presenting cells in the tumor microenvironment. The potential of using SOCS1 as a diagnostic marker and therapeutic target in tumor diagnosis, prognosis and treatment is discussed.

Dual biological effects of the cytokines interleukin-10 and interferon-γ

It is generally thought that each cytokine exerts either immune stimulatory (inflammatory) or immune inhibitory (antiinflammatory or regulatory) biological activities. However, multiple cytokines can enact both inhibitory and stimulatory effects on the immune system. Two of these cytokines are interleukin (IL)-10 and interferon-gamma (IFNγ). IL-10 has demonstrated antitumor immunity even though it has been known for years as an immunoregulatory protein. Generally perceived as an immune stimulatory cytokine, IFNγ can also induce inhibitory molecule expression including B7-H1 (PD-L1), indoleamine 2,3-dioxygenase (IDO), and arginase on multiple cell populations (dendritic cells, tumor cells, and vascular endothelial cells). In this review, we will summarize current knowledge of the dual roles of both of these cytokines and stress the previously underappreciated stimulatory role of IL-10 and inhibitory role of IFNγ in the context of malignancy. Our progressive understanding of the dual effects of these cytokines is important for dissecting cytokine-associated pathology and provides new avenues for developing effective immune therapy against human diseases, including cancer.

Signal transducers and activators of transcription-from cytokine signalling to cancer biology

Signal transducers and activators of transcription (STATs) are, as the name indicates, both signal transducers and transcription factors. STATs are activated by cytokines and some growth factors and thus control important biological processes. These include cell growth, cell differentiation, apoptosis and immune responses. Dysregulation of STATs, either due to constitutive activation or function impairment, can have, therefore, deleterious biological consequences. This review places particular emphasis on their structural organization, biological activities and regulatory mechanisms most commonly utilized by cells to control STAT-mediated signalling. STATs also play important roles in cancer and immune deficiencies and are thus being exploited as therapeutic targets.

Suppressor of cytokine signaling 1 regulates embryonic myelopoiesis independently of its effects on T cell development

Suppressor of cytokine signaling 1 (SOCS1) has been shown to play important roles in the immune system. It acts as a key negative regulator of signaling via receptors for IFNs and other cytokines controlling T cell development, as well as Toll receptor signaling in macrophages and other immune cells. To gain further insight into SOCS1, we have identified and characterized the zebrafish socs1 gene, which exhibited sequence and functional conservation with its mammalian counterparts. Initially maternally derived, the socs1 gene showed early zygotic expression in mesodermal structures, including the posterior intermediate cell mass, a site of primitive hematopoiesis. At later time points, expression was seen in a broad anterior domain, liver, notochord, and intersegmental vesicles. Morpholino-mediated knockdown of socs1 resulted in perturbation of specific hematopoietic populations prior to the commencement of lymphopoiesis, ruling out T cell involvement. However, socs1 knockdown also lead to a reduction in the size of the developing thymus later in embryogenesis. Zebrafish SOCS1 was shown to be able to interact with both zebrafish Jak2a and Stat5.1 in vitro and in vivo. These studies demonstrate a conserved role for SOCS1 in T cell development and suggest a novel T cell-independent function in embryonic myelopoiesis mediated, at least in part, via its effects on receptors using the Jak2-Stat5 pathway.

Diet-induced obesity in mice reduces the maintenance of influenza-specific CD8+ memory T cells

Obesity has been associated with increasing the risk for type 2 diabetes and heart disease, but its influence on the immune response to viral infection is understudied. Memory T cells generated during a primary influenza infection are important for protection against subsequent influenza exposures. Previously, we have demonstrated that diet-induced obese (DIO) mice have increased morbidity and mortality following secondary influenza infection compared with lean mice. To determine whether the problem resided in a failure to maintain functional, influenza-specific CD8(+) memory T cells, male DIO and lean mice were infected with influenza X-31. At 84 d postinfection, DIO mice had a 10% reduction in memory T cell numbers. This reduction may have resulted from significantly reduced memory T cell expression of interleukin 2 receptor beta (IL-2R beta, CD122), but not IL-7 receptor alpha (CD127), which are both required for memory cell maintenance. Peripheral leptin resistance in the DIO mice may be a contributing factor to the impairment. Indeed, leptin receptor mRNA expression was significantly reduced in the lungs of obese mice, whereas suppressor of cytokine signaling (Socs)1 and Socs3 mRNA expression were increased. It is imperative to understand how the obese state alters memory T cells, because impairment in maintenance of functional memory responses has important implications for vaccine efficacy in an obese population.