A family of cytokine-inducible inhibitors of signalling

Preclinical advances and the immunophysiology of a new therapeutic chagas disease vaccine

INTRODUCTION

Chronic infection with the protozoal parasite Trypanosoma cruzi leads to a progressive cardiac disease, known as chronic Chagasic cardiomyopathy (CCC). A new therapeutic Chagas disease vaccine is in development to augment existing antiparasitic chemotherapy drugs.

AREAS COVERED

We report on our current understanding of the underlying immunologic and physiologic mechanisms that lead to CCC, including parasite immune escape mechanisms that allow persistence and the subsequent inflammatory and fibrotic processes that lead to clinical disease. We report on vaccine design and the observed immunotherapeutic effects including induction of a balanced T_H1/T_H2/T_H17 immune response that leads to reduced parasite burdens and tissue pathology. Further, we report vaccine-linked chemotherapy, a dose sparing strategy to further reduce parasite burdens and tissue pathology.

EXPERT OPINION

Our vaccine-linked chemotherapeutic approach is a multimodal treatment strategy, addressing both the parasite persistence and the underlying deleterious host inflammatory and fibrotic responses that lead to cardiac dysfunction. In targeting treatment towards patients with chronic indeterminate or early determinate Chagas disease, this vaccine-linked chemotherapeutic approach will be highly economical and will reduce the global disease burden and deaths due to CCC.

Identification of selection signatures in Iranian dromedary and Bactrian camels using whole genome sequencing data

The Old World camels play an important role as one of the main food sources in large parts of Asia and Africa. Natural selection combined with artificial selection by human has affected parts of the domestic animal genome for adapting them to their habitats and meeting human needs. Here, we used whole genome sequencing data of 34 camels (including 14 dromedaries and 20 Bactrian camels) to identify the genomic signature of selection in the Iranian dromedary (ID) and Bactrian camels (IB). To detect the mentioned regions, we used two methods including population differentiation index (Fst) and cross-population extended haplotype homozygosity (XP-EHH) with 50 kb sliding window and 25 kb step size. Based on gene ontology analysis on the candidate genes identified for IB camels, we found GO terms associated with lung development, nervous system development, immune system and behavior. Also, we identified several genes related to body thermoregulation (ZNF516), meat quality (ANK1 and HSPA13), and high-altitude adaptation (OPA1) for IB camels. In the list of detected candidate genes under selection in ID camels, the genes related to energy metabolism (BDH1), reproduction (DLG1, IMMP2L and FRASI), long-term memory (GRIA1), kidney (SLC12A1), lung development (EMILIN2 and FBN1) and immunity (SOCS2, JAK1, NRROS and SENP1) were found. Our findings, along with further studies in this field, will strengthen our knowledge about the effect of selection on the camelid genome under different geographical, climatic and even cultural conditions.

The E3 ubiquitin ligase SOCS-7 reverses immunosuppression via Shc1 signaling in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common primary liver malignancies and is the third leading cause of tumor-related mortality worldwide. Despite advances in HCC treatment, diagnosis at the later stages, and the complex mechanisms relating to the cause and pathogenesis, results in less than 40% of HCC patients being eligible for potential therapy. Prolonged inflammation and resulting immunosuppression are major hallmarks of HCC; however, the mechanisms responsible for these processes have not been clearly elucidated. In this study, we identified SOCS-7, an inhibitor of cytokine signaling, as a novel regulator of immunosuppression in HCC. We found that SOCS-7 mediated E3 ubiquitin ligase activity on a signaling adaptor molecule, Shc1, in Huh-7 cells. Overexpression of SOCS-7 reduced the induction of immunosuppressive factors, TGF-β, Versican, and Arginase-1, and further reduced STAT3 activation. Furthermore, using an in vivo tumor model, we confirmed that SOCS-7 negatively regulates immunosuppression and inhibits tumor growth by targeting Shc1 degradation. Together, our study identified SOCS-7 as a possible therapeutic target to reverse immunosuppression in HCC.

Strawberry notch homolog 2 regulates the response to interleukin-6 in the central nervous system

BACKGROUND

The cytokine interleukin-6 (IL-6) modulates a variety of inflammatory processes and, context depending, can mediate either pro- or anti-inflammatory effects. Excessive IL-6 signalling in the brain is associated with chronic inflammation resulting in neurodegeneration. Strawberry notch homolog 2 (Sbno2) is an IL-6-regulated gene whose function is largely unknown. Here we aimed to address this issue by investigating the impact of Sbno2 disruption in mice with IL-6-mediated neuroinflammation.

METHODS

Mice with germline disruption of Sbno2 (Sbno2-/-) were generated and crossed with transgenic mice with chronic astrocyte production of IL-6 (GFAP-IL6). Phenotypic, molecular and transcriptomic analyses were performed on tissues and primary cell cultures to clarify the role of SBNO2 in IL-6-mediated neuroinflammation.

RESULTS

We found Sbno2-/- mice to be viable and overtly normal. By contrast GFAP-IL6 × Sbno2-/- mice had more severe disease compared with GFAP-IL6 mice. This was evidenced by exacerbated neuroinflammation and neurodegeneration and enhanced IL-6-responsive gene expression. Cell culture experiments on primary astrocytes from Sbno2-/- mice further showed elevated and sustained transcript levels of a number of IL-6 stimulated genes. Notably, despite enhanced disease in vivo and gene expression both in vivo and in vitro, IL-6-stimulated gp130 pathway activation was reduced when Sbno2 is disrupted.

CONCLUSION

Based on these results, we propose a role for SBNO2 as a novel negative feedback regulator of IL-6 that restrains the excessive inflammatory actions of this cytokine in the brain.

Suppressors of Cytokine Signaling and Hepatocellular Carcinoma

Simple Summary

Hepatocellular carcinoma (HCC) is a common malignancy worldwide. The HCC generally develops in the liver of patients already suffering from chronic liver disease. There have been significant advances in both the curative and palliative treatment of HCC. Although liver resection is a curative treatment for HCC, its indication is often limited due to an impaired liver function reservoir. There is still a need to understand how to control liver regeneration after resection and find better cancer immunotherapy and anticancer drugs for advanced HCC. Suppressors of cytokine signaling (SOCS) negatively regulate cytokine signaling related to cell proliferation, differentiation, and immune response; therefore, SOCS are thought to play an important role in HCC development and liver regeneration.

Abstract

Cytokines are secreted soluble glycoproteins that regulate cellular growth, proliferation, and differentiation. Suppressors of cytokine signaling (SOCS) proteins negatively regulate cytokine signaling and form a classical negative feedback loop in the signaling pathways. There are eight members of the SOCS family. The SOCS proteins are all comprised of a loosely conserved N-terminal domain, a central Src homology 2 (SH2) domain, and a highly conserved SOCS box at the C-terminus. The role of SOCS proteins has been implicated in the regulation of cytokines and growth factors in liver diseases. The SOCS1 and SOCS3 proteins are involved in immune response and inhibit protective interferon signaling in viral hepatitis. A decreased expression of SOCS3 is associated with advanced stage and poor prognosis of patients with hepatocellular carcinoma (HCC). DNA methylations of SOCS1 and SOCS3 are found in HCC. Precise regulation of liver regeneration is influenced by stimulatory and inhibitory factors after partial hepatectomy (PH), in particular, SOCS2 and SOCS3 are induced at an early time point after PH. Evidence supporting the important role of SOCS signaling during liver regeneration also supports a role of SOCS signaling in HCC. Immuno-oncology drugs are now the first-line therapy for advanced HCC. The SOCS can be potential targets for HCC in terms of cell proliferation, cell differentiation, and immune response. In this literature review, we summarize recent findings of the SOCS family proteins related to HCC and liver diseases.

SOCS1, the feedback regulator of STAT1/3, inhibits the osteogenic differentiation of rat bone marrow mesenchymal stem cells

Our study showed that Signal transducer and activator of transcription (STAT)1 and STAT3 phosphorylation was firstly upregulated in the early stage of osteogenic differentiation (OD), and quickly eliminated in hours. Following with phosphorylation of STAT1/3, its downstream feedback regulator Suppressor of cytokine signaling 1 (SOCS1) protein also underwent a quick elevation. Further activation and deactivation of STAT1/3, by administrated with Colivelin and Nifuroxazide in Bone mesenchymal stem cells (BMSCs), increased and decreased SOCS1 expression, inhibited and promoted OD of BMSCs, respectively, as evidenced by Alizarin staining, alkaline phosphatase (ALP) activity, and determination of Run-related transcription factor 2 (RUNX2), Osteocalcin (OCN), ALP, and Bone sialoprotein (BSP). In addition, administration of Colivelin and Nifuroxazide caused and blocked inflammation and apoptosis of BMSCs. To further elucidate the role of STAT1/3-SOCS1 regulatory loop on OD of BMSCs, we overexpressed or silenced SOCS1 in BMSCs during OD. WB data showed that overexpression of SOCS1 repressed STAT1/3 phosphorylation, and knockdown of SOCS1 increased the phosphorylated STAT1/3. Further mechanism study showed that OD of BMSCs was elevated or reduced by SOCS1 overexpression or knockdown, respectively. The findings presenting indicated that the STAT1/3-SOCS1 axis may be exploited as an innovative strategy to enhance osteogenesis in regenerative medicine.

Molecular characterization and immunoregulatory analysis of suppressors of cytokine signaling 1 (SOCS1) in black rockfish, Sebastes schlegeli

The suppressors of cytokine signaling (SOCS) family are important soluble mediators to inhibit signal transduction via the Janus kinase/signal transducer and activator of transcription (JAK-STAT) pathway in the innate and adaptive immune responses. SOCS1 is the primary regulator of a number of cytokines. In this study, two spliced transcripts of SOCS1 were identified and characterized from black rockfish (Sebastes schlegeli), named SsSOCS1a and SsSOCS1b. SsSOCS1a and SsSOCS1b contained conserved structural and functional domains including KIR region, ESS region, SH2 domain and SOCS box. SsSOCS1a and SsSOCS1b were distributed ubiquitously in all the detected tissues with the higher expression level in liver and spleen. After stimulation in vivo with Vibrio anguillarum and Edwardsiella tarda, the mRNA expression of SsSOCS1a and SsSOCS1b were induced in most of the immune-related tissues, including head kidney, spleen and liver. Meanwhile, poly I:C and IFNγ up-regulated the expression of SsSOCS1a and SsSOCS1b that reached the highest level at 24 h in macrophages in vitro. Luciferase assays in HEK293 cells showed SsSOCS1a and SsSOCS1b had the similar function in inhibiting ISRE activity after poly I:C and IFNγ treatment. Furthermore, KIR domain in black rockfish was determined to have a negative regulatory role in IFN signaling. SsSOCS1a and SsSOCS1b were found to interact strongly with each other by Co-immunoprecipitation analyses. These results indicated that the function of SOCS1 in the negative regulation of IFN signaling is conserved from teleost to mammals which will be helpful to further understanding of the biological functions of teleosts SOCS1 in innate immunity.

Cytokine-inducible SH2 domain containing protein contributes to regulation of adiposity, food intake, and glucose metabolism

The cytokine-inducible SH2 domain containing protein (CISH) is the founding member of the suppressor of cytokine signaling (SOCS) family of negative feedback regulators and has been shown to be a physiological regulator of signaling in immune cells. This study sought to investigate novel functions for CISH outside of the immune system. Mice deficient in CISH were generated and analyzed using a range of metabolic and other parameters, including in response to a high fat diet and leptin administration. CISH knockout mice possessed decreased body fat and showed resistance to diet-induced obesity. This was associated with reduced food intake, but unaltered energy expenditure and microbiota composition. CISH ablation resulted in reduced basal expression of the orexigenic Agrp gene in the arcuate nucleus (ARC) region of the brain. Cish was basally expressed in the ARC, with evidence of co-expression with the leptin receptor (Lepr) gene in Agrp-positive neurons. CISH-deficient mice also showed enhanced leptin responsiveness, although Cish expression was not itself modulated by leptin. CISH-deficient mice additionally exhibited improved insulin sensitivity on a high-fat diet, but not glucose tolerance despite reduced body weight. These data identify CISH as an important regulator of homeostasis through impacts on appetite control, mediated at least in part by negative regulation of the anorexigenic effects of leptin, and impacts on glucose metabolism.

Interferons limit autoantigen-specific CD8+ T-cell expansion in the non-obese diabetic mouse

Interferon gamma (IFNγ) is a proinflammatory cytokine implicated in autoimmune diseases. However, deficiency or neutralization of IFNγ is ineffective in reducing disease. We characterize islet antigen-specific T cells in non-obese diabetic (NOD) mice lacking all three IFN receptor genes. Diabetes is minimally affected, but at 125 days of age, antigen-specific CD8⁺ T cells, quantified using major histocompatibility complex class I tetramers, are present in 10-fold greater numbers in Ifngr-mutant NOD mice. T cells from Ifngr-mutant mice have increased proliferative responses to interleukin-2 (IL-2). They also have reduced phosphorylated STAT1 and its target gene, suppressor of cytokine signaling 1 (SOCS-1). IFNγ controls the expansion of antigen-specific CD8⁺ T cells by mechanisms which include increased SOCS-1 expression that regulates IL-2 signaling. The expanded CD8⁺ T cells are likely to contribute to normal diabetes progression despite reduced inflammation in Ifngr-mutant mice.

Phosphorylation-Induced Conformational Dynamics and Inhibition of Janus Kinase 1 by Suppressors of Cytokine Signaling 1

The dysfunction of the JAK/STAT (Janus kinase/signal transducers and activators of transcription) pathway results in several pathophysiological conditions, including autoimmune disorders. The negative feedback regulators of the JAK/STAT signaling pathway, suppressors of cytokine signaling (SOCS), act as a natural inhibitor of JAK and inhibit aberrant activity. SOCS1 is the most potent member of the SOCS family, whose kinase inhibitory region targets the substrate-binding groove of JAK with high affinity and blocks the phosphorylation of JAK kinases. Overall, we performed an aggregate of 13 μs molecular dynamics simulations on the activation loop's three different phosphorylation (double and single) states. Results from our simulations show that the single Tyr¹⁰³⁴ phosphorylation could stabilize the JAK1/SOCS1 complex as well as the flexible activation segment. The phosphate-binding loop (P-loop) shows conformational variability at dual and single phosphorylated states. Principal component analysis and protein structure network (PSN) analysis reveal that the different phosphorylation states and SOCS1 binding induce intermediate inactive conformations of JAK1, which could be a better target for future JAK1 selective drug design. PSN analysis suggests that the com-pY1034 system is stabilized due to higher values of network hubs than the other two complex systems. Moreover, the binding free energy calculations suggest that pTyr¹⁰³⁴ states show a higher affinity toward SOCS1 than the dual and pTyr¹⁰³⁵ states. We believe that the mechanistic understanding of JAK1/SOCS1 complexation will aid future studies related to peptide inhibitors based on SOCS1.

SOCS-1 1478 CA/del gene polymorphism affects survival in colorectal carcinoma

Aims and Background

Suppressor of cytokine signaling 1 (SOCS1) is a prototype molecule of the SOCS family. Alterations in the SOCS1 expression have been reported in human cancers and some studies suggest that SOCS1 might act as a tumor suppressor in carcinogenesis. In the present study, we aimed to evaluate the association of SOCS1 promoter -1478CA/del gene polymorphism detected in DNA isolated from the tissues of patients with colorectal cancer (CRC) for histopathological characteristics and survival.

Patients and Methods

For the study, we retrospectively enrolled 53 patients with resected colon due to CRC and 23 control subjects with no systemic illness. SOCS1- 1478CA/del gene polymorphism was determined using the polymerase chain reaction-restriction fragment length polymorphism methodology. These results were evaluated in relation to histopathological features and survival results and analyzed statistically. A P value equal to or less than 0.05 was considered significant.

Results

Neither control subjects nor the CRC group showed a significant association with SOCS1 -1478CA/del gene polymorphism (p = 0.248). SOCS1 -1478CA/del gene polymorphism was not significantly associated with histopathological features either. However, in the overall survival (OS) analysis, those patients with the del/del allele were found to have a 3.9-fold greater risk of mortality compared to those with CA/CA allele (p = 0.05). Progression-free survival (PFS) was also significantly different in such patients (p = 0.05).

Conclusion

The present study examining the association of SOCS1 -1478CA/del gene polymorphism with CRC showed that CRC patients with del/del allele had both significantly shorter PFS and OS versus those with CA/CA or CA/del allele.

Suppressor of cytokine signaling 1 (SOCS1) inhibits antiviral responses to facilitate Senecavirus A infection by regulating the NF-κB signaling pathway

Senecavirus A (SVA) is a new virus inducing porcine idiopathic vesicular disease that causes significant economic losses. Although some progress has been made in etiological research, the role of host factors in SVA infection remains unclear. This study investigated the role of the host factor, suppressor of cytokine signaling 1 (SOCS1), in SVA infection. The expression of SOCS1 was significantly upregulated with infection of SVA in a dose-dependent manner, and SOCS1 inhibited the expression of type I interferons (IFN-α, IFN-β) and the production of interferon stimulating genes (ISGs) (ISG56, ISG54, PKR), thereby facilitating viral replication. Further results showed that inhibition of antiviral responses of SOCS1 was achieved by regulating the NF-κB signaling pathway, which attenuates the production of IFNs and pro-inflammatory cytokines. These findings provide a new perspective of SVA pathogenesis and may partially explain the persistence of this infection. Moreover, the data indicate that targeting SOCS1 can help in developing new agents against SVA infection.

CTLA4Ig/VISTAIg combination therapy selectively induces CD4+ T cell-mediated immune tolerance by targeting the SOCS1 signaling pathway in porcine islet xenotransplantation

T cell inhibitory receptors can regulate the proliferation or function of T cells by binding to their ligands and present a unique opportunity to manage destructive immune responses during porcine islet xenotransplantation. We applied ex vivo porcine islet xenotransplantation and in vitro mixed lymphocyte-islet reaction models to assess immune checkpoint receptor expression profiles in recipient T cells, investigate whether CTLA4 or VISTA immunoglobulin (Ig) combination therapy alone could suppress porcine islet xenograft rejection and further analyze its potential immune tolerance mechanism. Recipient T cells expressed moderate to high levels of CTLA4, PD-1, TIGIT, and VISTA, and the frequency of CTLA4⁺ CD4⁺ , TIGIT⁺ CD4⁺ , VISTA⁺ CD4⁺ and VISTA⁺ CD8⁺ T cells was positively correlated with porcine islet xenograft survival time in xenotransplant recipients. Combined treatment with CTLA4Ig and VISTAIg selectively inhibited recipient CD4⁺ T cell hyperresponsiveness and proinflammatory cytokine production and significantly delayed xenograft rejection. SOCS1 deficiency in CD4⁺ T cells stimulated by xenogeneic islets facilitated hyperresponsiveness and abolished the suppressive effect of combination therapy on recipient T cell-mediated porcine islet damage in vivo and in vitro. Further mechanistic studies revealed that combined treatment significantly induced SOCS1 expression and inhibited the Jak-STAT signaling pathway in wild-type recipient CD4⁺ T cells stimulated by xenogeneic islets, whereas SOCS1 deficiency resulted in Jak-STAT signaling pathway activation in recipient CD4⁺ T cells. We demonstrated a major role for CTLA4 and VISTA as key targets in CD4⁺ T cell hyperresponsiveness and porcine islet xenograft rejection. The selective inhibition of CD4⁺ T cell immunity by CTLA4Ig/VISTAIg is based on SOCS1-dependent signaling.

Mechanisms of reduced leptin-mediated satiety signaling during obesity

BACKGROUND/OBJECTIVES

Disrupted leptin signaling in vagal afferent neurons contributes to hyperphagia and obesity. Thus, we tested the hypothesis that intrinsic negative regulators of leptin signaling, suppressor of cytokine signaling 3 (SOCS3) and protein tyrosine phosphatase 1B (PTP1B) underlie dysfunctional leptin-mediated vagal afferent satiety signaling during obesity.

METHODS

Experiments were performed on standard chow-fed control mice, high-fat fed (HFF), or low-fat fed (LFF) mice. SOCS3 and PTP1B expression were quantified using western blot and quantitative PCR. Nodose ganglion neuronal excitability and jejunal afferent sensitivity were measured by patch clamp and extracellular afferent recordings, respectively.

RESULTS

Increased expression of SOCS3 and PTP1B were observed in the jejunum of HFF mice. Prolonged incubation with leptin attenuated nodose ganglion neuronal excitability, and this effect was reversed by inhibition of SOCS3. Leptin potentiated jejunal afferent nerve responses to CCK in LFF mice but decreased them in HFF mice. Inhibition of SOCS3 restored impaired vagal afferent neuronal excitability and afferent nerve responses to satiety mediators during obesity. Two-pore domain K⁺ channel (K_2P) conductance and nitric oxide (NO) production that we previously demonstrated were elevated during obesity were decreased by inhibitions of SOCS3 or PTP1B.

CONCLUSIONS

This study suggests that obesity impairs vagal afferent sensitivity via SOCS3 and PTP1B, likely as a consequence of obesity-induced hyperleptinemia. The mechanisms underlying leptin resistance appear also to cause a more global impairment of satiety-related vagal afferent responsiveness.

Circulating Exosomal miR-1290 for Diagnosis of Epithelial Ovarian Cancer

The aim of the study was to develop a new diagnostic biomarker for identifying serum exosomal miRNAs specific to epithelial ovarian cancer (EOC) and to find out target gene of the miRNA for exploring the molecular mechanisms in EOC. A total of 84 cases of ovarian masses and sera were enrolled, comprising EOC (n = 71), benign ovarian neoplasms (n = 13). We detected expression of candidate miRNAs in the serum and tissue of both benign ovarian neoplasm group and EOC group using real-time polymerase chain reaction. Immunohistochemistry were constructed using formalin fixed paraffin embedded (FFPE) tissue to detect expression level of suppressor of cytokine signaling 4 (SOCS4). In the EOC group, miRNA-1290 was significantly overexpressed in serum exosomes and tissues as compared to benign ovarian neoplasm group (fold change ≥ 2, p < 0.05). We observed area under the receiver operating characteristic curve (AUC) for miR-1290, using a cut-off of 0.73, the exosomal miR-1290 from serum had AUC, sensitivity, and specificity values of 0.794, 69.2 and 87.3, respectively. In immunohistochemical study, expression of SOCS4 in EOC was lower than that in benign ovarian neoplasm. Serum exosomal miR-1290 could be considered as a biomarker for differential diagnosis of EOC from benign ovarian neoplasm and SOCS4 might be potential target gene of miR-1290 in EOC.

Elimination of negative feedback in TLR signalling allows rapid and hypersensitive detection of microbial contaminants

The exquisite specificity of Toll-like receptors (TLRs) to sense microbial molecular signatures is used as a powerful tool to pinpoint microbial contaminants. Various cellular systems, from native human blood cells to transfected cell lines exploit TLRs as pyrogen detectors in biological preparations. However, slow cellular responses and limited sensitivity have hampered the replacement of animal-based tests such as the rabbit pyrogen test or lipopolysaccharide detection by Limulus amoebocyte lysate. Here, we report a novel human cell-based approach to boost detection of microbial contaminants by TLR-expressing cells. By genetic and pharmacologic elimination of negative control circuits, TLR-initiated cellular responses to bacterial molecular patterns were accelerated and significantly elevated. Combining depletion of protein phosphatase PP2ACA and pharmacological inhibition of PP1 in the optimized reporter cells further enhanced the sensitivity to allow detection of bacterial lipoprotein at 30 picogram/ml. Such next-generation cellular monitoring is poised to replace animal-based testing for microbial contaminants.

The Tyrosine Kinase Tec Regulates Effector Th17 Differentiation, Pathogenicity, and Plasticity in T-Cell-Driven Intestinal Inflammation

T helper (Th) 17 cells are not only key in controlling infections mediated by extracellular bacteria and fungi but are also triggering autoimmune responses. Th17 cells comprise heterogeneous subsets, some with pathogenic functions. They can cease to secrete their hallmark cytokine IL-17A and even convert to other T helper lineages, a process known as transdifferentiation relying on plasticity. Both pathogenicity and plasticity are tightly linked to IL-23 signaling. Here, we show that the protein tyrosine kinase Tec is highly induced in Th17 cells. Th17 differentiation was enhanced at low interleukin-6 (IL-6) concentrations in absence of Tec, which correlates with increased STAT3 phosphorylation and higher Il23r expression. Therefore, we uncovered a function for Tec in the IL-6 sensing via STAT3 by CD4⁺ T cells, defining Tec as a fine-tuning negative regulator of Th17 differentiation. Subsequently, by using the IL-17A fate mapping mouse combined with in vivo adoptive transfer models, we demonstrated that Tec not only restrained effector Th17 differentiation but also pathogenicity and plasticity in a T-cell intrinsic manner. Our data further suggest that Tec regulates inflammatory Th17-driven immune responses directly impacting disease severity in a T-cell-driven colitis model. Notably, consistent with the in vitro findings, elevated levels of the IL-23 receptor (IL-23R) were observed on intestinal pre- and postconversion Th17 cells isolated from diseased Tec^-/- mice subjected to adoptive transfer colitis, highlighting a fundamental role of Tec in restraining IL-23R expression, likely via the IL-6-STAT3 signaling axis. Taken together, these findings identify Tec as a negative regulator of Th17 differentiation, pathogenicity, and plasticity, contributing to the mechanisms which help T cells to orchestrate optimal immune protection and to restrain immunopathology.

Identification of the Prognostic Value Among Suppressor Of Cytokine Signaling Family Members in Kidney Renal Clear Cell Carcinoma

Background: Kidney renal clear cell carcinoma (KIRC) has become one of the most prevalent malignancies worldwide and remains a crucial cause of cancer-related morbidity and mortality. Aberrant activation of the JAK/STAT pathway acts as an important role in KIRC. The suppressor of cytokine signaling (SOCS) family members are the key negative regulators of the JAK/STAT pathway. SOCS family members have been verified to act as significant roles in regulating cellular responses to many cytokines and growth factors. However, whether the expression levels of SOCS affect the prognosis of patients with KIRC is still elusive.

Methods: We first evaluated the expression of SOCS family genes in KIRC and determined the correlation between SOCS expression and different clinicopathological features. Then, we analyzed the genetic alterations, potential functions, transcription factor targets, and immune infiltration of SOCS family members based on the information available on public databases. Finally, we assessed the prognostic value of differentially expressed SOCS family members.

Results: The expression levels of SOCS2, SOCS4, SOCS6, SOCS7, and CISH were downregulated in KIRC, and all SOCS genes were associated with clinicopathological features of patients with KIRC. SOCS family members have been predominantly related to protein binding, signaling adaptor activity, and JAK/STAT cascade. We found that STAT3, STAT6, and IRF1 are the key transcription factors that may be participated in the regulation of SOCS. We also found an association between the expression levels of SOCS and the immune infiltrates of KIRC. Finally, we have illuminated that SOCS1 and SOCS3 are risky genes, whereas SOCS2, SOCS4, SOCS6, SOCS7, and CISH are some of the protective genes for patients with KIRC; based on these, we have created a KIRC prognostic index for predicting the prognosis of patients of KIRC.

Conclusion: Our study may contribute to further understanding the functions of SOCS genes in KIRC, which may help clinicians in selecting the appropriate drugs and predicting the outcomes for patients with KIRC.

Immunopathology of RSV: An Updated Review

RSV is a leading cause of respiratory tract disease in infants and the elderly. RSV has limited therapeutic interventions and no FDA-approved vaccine. Gaps in our understanding of virus-host interactions and immunity contribute to the lack of biological countermeasures. This review updates the current understanding of RSV immunity and immunopathology with a focus on interferon responses, animal modeling, and correlates of protection.

SOCS-2 gene expression at diagnosis does not predict for outcome of chronic myeloid leukemia patients on imatinib treatment

SOCS-2 gene expression at diagnosis has been suggested as a predictor of clinical outcome in chronic myeloid leukemia (CML). In this study SOCS-2 and GUS expression levels were determined by real-time PCR in pretherapeutic samples at diagnosis. First, three patient groups were compared after assessment at 48 months: optimal molecular responders (n = 35), patients with resistance to imatinib (n = 28), and blast crisis patients (n = 27). A significant difference in SOCS-2 gene expression at diagnosis was observed comparing blast crisis vs. resistant patients (p = 0.042) and optimal responders (p = 0.010). Second, a validation sample of consecutively randomized patients (n = 123) was investigated. No discriminative SOCS-2 gene expression cutoff could be derived to predict molecular or cytogenetic response, progression-free or overall survival. Although SOCS-2 gene was differentially expressed at the time of diagnosis in blast crisis patients when compared to other groups, a prognostic impact in consecutively randomized patients was not observed.

Discovery of an exosite on the SOCS2-SH2 domain that enhances SH2 binding to phosphorylated ligands

Suppressor of cytokine signaling (SOCS)2 protein is a key negative regulator of the growth hormone (GH) and Janus kinase (JAK)-Signal Transducers and Activators of Transcription (STAT) signaling cascade. The central SOCS2-Src homology 2 (SH2) domain is characteristic of the SOCS family proteins and is an important module that facilitates recognition of targets bearing phosphorylated tyrosine (pTyr) residues. Here we identify an exosite on the SOCS2-SH2 domain which, when bound to a non-phosphorylated peptide (F3), enhances SH2 affinity for canonical phosphorylated ligands. Solution of the SOCS2/F3 crystal structure reveals F3 as an α-helix which binds on the opposite side of the SH2 domain to the phosphopeptide binding site. F3:exosite binding appears to stabilise the SOCS2-SH2 domain, resulting in slower dissociation of phosphorylated ligands and consequently, enhances binding affinity. This biophysical enhancement of SH2:pTyr binding affinity translates to increase SOCS2 inhibition of GH signaling.

Combination of two monoclonal antibodies with SOCS1 N- and C-terminal binding sites to address SOCS1 status in B cells and B-cell lymphoma

INTRODUCTION

Accumulating studies show that the tumour suppressor SOCS1 is one of the most frequently mutated genes in lymphomas, often affecting the coding sequence of SOCS1 protein. Depending on the type of mutation and lymphoma concerned, SOCS1 mutations have different impacts on progression-free and overall survival. Two antibodies binding the N and C terminals of SOCS1 would be a suitable 'test pair' to identify truncated versions of SOCS1. We, therefore, compared the C-terminal antibody 424C with the N-terminal antibody 4H1.

MATERIALS AND METHODS

As 424C has already been characterised, we performed a comparative analysis of anti-SOCS1 antibody 4H1 using immunohistochemistry on human tonsil tissue and chamber slides, immunoblots on SOCS1 wildtype and mutated transfected HEK293T cells and lymphoma cell lines and cross-reactivity analysis and epitope mapping with protein microarrays.

RESULTS

Compared with 424C, anti-SOCS1 antibody 4H1 showed various cross-reactions with other proteins resulting in a 'pancellular' immunohistochemical staining pattern in FFPE lymphoid tissue. Like 424C, 4H1 identified SOCS1 wildtype and SOCS1 mutations in immunoblot experiments but also bound an unknown protein with high intensity.

CONCLUSION

Anti-SOCS1 antibody 4H1 may be useful in a molecular setting but is disqualified as an immunohistochemical diagnostic tool due to its very broad non-specific binding.

MicroRNAs and JAK/STAT3 signaling: A new promising therapeutic axis in blood cancers

Blood disorders include a wide spectrum of blood-associated malignancies resulting from inherited or acquired defects. The ineffectiveness of existing therapies against blood disorders arises from different reasons, one of which is drug resistance, so different types of leukemia may show different responses to treatment. Leukemia occurs for a variety of genetic and acquired reasons, leading to uncontrolled proliferation in one or more cell lines. Regarding the genetic defects, oncogene signal transducer and activator of transcription (STAT) family transcription factor, especially STAT3, play an essential role in hematological disorders onset and progress upon mutations, dysfunction, or hyperactivity. Besides, microRNAs, as biological molecules, has been shown to play a dual role in either tumorigenesis and tumor suppression in various cancers. Besides, a strong association between STAT3 and miRNA has been reported. For example, miRNAs can regulate STAT3 via targeting its upstream mediators such as IL6, IL9, and JAKs or directly binding to the STAT3 gene. On the other hand, STAT3 can regulate miRNAs. In this review study, we aimed to determine the role of either microRNAs and STAT3 along with their effect on one another's activity and function in hematological malignancies.

SOCS proteins and their roles in the development of glioblastoma

Glioblastoma multiforme (GBM) is the most common type of primary brain tumor in adults. GBM is characterized by a high degree of malignancy and aggressiveness, as well as high morbidity and mortality rates. GBM is currently treatable via surgical resection, chemotherapy and radiotherapy, but the prognosis of patients with GBM is poor. The suppressor of cytokine signaling (SOCS) protein family comprises eight members, including SOCS1-SOCS7 and cytokine-inducible SH2-containing protein. SOCS proteins regulate the biogenesis of GBM via the JAK/STAT and NF-κB signaling pathways. Driven by NF-κB, the expression of SOCS proteins can serve as a negative regulator of the JAK/STAT signaling pathway and exerts a potential inhibitory effect on GBM. In GBM, E3 ubiquitin ligase is involved in the regulation of cellular functions, such as the receptor tyrosine kinase (RTK) survival signal, in which SOCS proteins negatively regulate RTK signaling, and kinase overexpression or mutation can lead to the development of malignancies. Moreover, SOCS proteins affect the proliferation and differentiation of GBM cells by regulating the tumor microenvironment. SOCS proteins also serve specific roles in GBM of different grades and different isocitrate dehydrogenase mutation status. The aim of the present review was to describe the biogenesis and function of the SOCS protein family, the roles of SOCS proteins in the microenvironment of GBM, as well as the role of this protein family and E3 ubiquitin ligases in GBM. Furthermore, the role of SOCS proteins as diagnostic and prognostic markers in GBM and their potential role as GBM therapeutics were explored.

The membrane-associated E3 ubiquitin ligase MARCH3 downregulates the IL-6 receptor and suppresses colitis-associated carcinogenesis

The IL-6-STAT3 axis is critically involved in inflammation-associated carcinogenesis (IAC). How this axis is regulated to modulate IAC remains unknown. Here, we show that the plasma membrane-associated E3 ubiquitin ligase MARCH3 negatively regulates STAT3 activation triggered by IL-6, as well as another IL-6 subfamily member, Oncostatin M (OSM). MARCH3 is associated with the IL-6 receptor α-chain (IL-6Rα) and its coreceptor gp130. Biochemical experiments indicated that MARCH3 mediates the polyubiquitination of IL-6Rα at K401 and gp130 at K849 following IL-6 stimulation, leading to their translocation to and degradation in lysosomes. MARCH3 deficiency increases IL-6- and OSM-triggered activation of STAT3 and induction of downstream effector genes in various cell types. MARCH3 deficiency enhances dextran sulfate sodium (DSS)-induced STAT3 activation, increases the expression of inflammatory cytokines, and exacerbates colitis, as well as azoxymethane (AOM)/DSS-induced colitis-associated cancer in mice. In addition, MARCH3 is downregulated in human colorectal cancer tissues and associated with poor survival across different cancer types. Our findings suggest that MARCH3 is a pivotal negative regulator of IL-6-induced STAT3 activation, inflammation, and inflammation-associated carcinogenesis.

Significance of Interleukin (IL)-4 and IL-13 in Inflammatory Arthritis

Interleukin (IL)-4 and IL-13 belong to the T helper 2 (Th2) cytokine family, along with IL-3, IL-5, and IL-9. These cytokines are key mediators of allergic inflammation. They have important immunomodulatory activities and exert influence on a wide variety of immune cells, such as B cells, eosinophils, basophils, monocytes, fibroblasts, endothelial cells, airway epithelial cells, smooth muscle cells, and keratinocytes. Recent studies have implicated IL-4 and IL-13 in the development of various autoimmune diseases. Additionally, these cytokines have emerged as potential players in pathogenesis of inflammatory arthritis. Recent findings suggest that the IL-4 and IL-13 might play a significant role in the downregulation of inflammatory processes underlying RA pathology, and beneficially modulate the course of the disease. This review summarizes the biological features of the IL-4 and IL-13 and provides current knowledge regarding the role of these cytokines in inflammatory arthritis.

Emerging role of signal transducer and activator of transcription 3 (STAT3) in pituitary adenomas

Pituitary adenomas are benign tumours that can cause an individual various clinical manifestations including tumour mass effects and/or the diverse effects of abnormal pituitary hormone secretion. Given the morbidity and limited treatment options for pituitary adenomas, there is a need for better biomarkers and treatment options. One molecule that is of specific interest is the signal transducer and activator of transcription 3 (STAT3), a transcription factor that plays a critical role in mediating cytokine-induced changes in gene expression. In addition, STAT3 controls cell proliferation by regulating mitochondrial activity. Not only does activation of STAT3 play a crucial role in tumorigenesis, including pituitary tumorigenesis, but a number of studies also demonstrate pharmacological STAT3 inhibition as a promising treatment approach for many types of tumours, including pituitary tumours. This review will focus on the role of STAT3 in different pituitary adenomas, in particular, growth hormone-producing adenomas and null cell adenomas. Furthermore, how STAT3 is involved in the cell proliferation and hormone regulation in pituitary adenomas and its potential role as a molecular therapeutic target in pituitary adenomas will be summarized.

Function and proteolytic generation of the soluble interleukin-6 receptor in health and disease

The pleiotropic cytokine interleukin-6 (IL-6) is involved in numerous physiological and pathophysiological functions that include development, immune cell differentiation, inflammation and cancer. IL-6 can signal via the membrane-bound IL-6 receptor (IL-6R, classic signaling) or via soluble forms of the IL-6R (sIL-6R, trans-signaling). Both modes of signaling induce the formation of a homodimer of the signal transducing β-receptor glycoprotein 130 (gp130) and the activation of several intracellular signaling cascades, e.g. the Jak/STAT pathway. Intriguingly, only IL-6 trans-signaling is required for the pro-inflammatory properties of IL-6, while regenerative and anti-inflammatory functions are mediated via classic signaling. The sIL-6R is generated by different molecular mechanisms, including alternative mRNA splicing, proteolysis of the membrane-bound IL-6R and the release of extracellular vesicles. In this review, we give an in-depth overview on these molecular mechanisms with a special emphasize on IL-6R cleavage by the metalloprotease ADAM17 and other proteases. We discuss the biological functions of the sIL-6R and highlight attempts to selectively block IL-6 trans-signaling in pre-clinical animal models as well as in clinical studies in patients with inflammatory bowel disease.

Nanotechnology based advanced therapeutic strategies for targeting interleukins in chronic respiratory diseases

Both communicable and non-communicable chronic respiratory conditions have accorded for suffering of millions of people of all ages and stated to be leading cause of death, morbidity, economic and social pressures, and disability-adjusted life-years (DALYs) worldwide. These illnesses impair patient's health and negatively impacts families and society, particularly in low and middle-income countries. Chronic respiratory diseases (CRDs) affect different organs of respiratory system, involving airways, parenchyma, and pulmonary vasculature. As the number of respiratory diseases are exponentially escalating but still the stakeholders are not paying attention towards its serious complications. Currently, the treatment being used primarily focusses only on alleviating symptoms of these illness rather delivering the therapeutic agent at target site for optimal care and/or prevention. Lately, extensive research is being conducted on airways and systemic inflammation, oxidative stress, airway, or parenchymal rehabilitation. From which macrophages, neutrophils, and T cells, as well as structural cells as fibroblasts, epithelial, endothelial, and smooth muscle cells have been found to be active participants that are involved in these chronic respiratory diseases. The pathogenesis of all these chronic respiratory diseases gets caused differently via mediators and proteins, including cytokines, chemokines, growth factors and oxidants. Presently, the target of prescription therapies is to reduce the inflammation of airways and relieve the airway contraction. In all studies, cytokines have been found to play an imperative role in fostering chronic airway inflammation and remodelling. Owing to the limitations of conventional treatments, the current review aims to summarize the current knowledge about the chronic respiratory disease and discuss further about the various conventional methods that can be used for treating this ailment. Additionally, it also highlights and discusses about the advanced drug delivery system that are being used for targeting the interleukins for the treatment of CRDs.

Association between inflammatory cytokines and caregiving distress in family caregivers of cancer patients

PURPOSE

Caregivers of cancer patients experience distress that can manifest as caregiving burden, burnout, depression, and fatigue. Caregiving distress affects physical health in various ways such as causing the dysregulation of inflammatory functions. We examined the relationships between psychological distress experienced by and inflammatory cytokine levels of family caregivers of cancer patients.

METHODS

A descriptive, cross-sectional study involving 93 family caregivers of cancer patients was conducted. Self-report questionnaires were used to measure the distress variables, which included the caregiving burden, burnout, depression, and fatigue, and peripheral blood samples were collected to measure the IL-6, IL-10, and TNF-α levels. Multiple linear regression analyses were conducted to evaluate the impact of caregivers' distress on their inflammatory cytokine levels.

RESULTS

Inflammatory cytokine levels were negatively correlated with caregiving distress. High fatigue levels (B =  - 0.047, p = 0.026) and additional days of care provided per week (B =  - 0.048, p = 0.009) was associated with low IL-6 levels. High depression levels (B =  - 0.250, p = 0.007), high fatigue levels (B =  - 0.054, p = 0.027), and more days of care provided per week (B =  - 0.048, p = 0.033) were associated with low TNF-α levels. The age of the caregiver (B =  - 0.011, p = 0.020) and days of care provided per week (B =  - 0.138, p = 0.031) were associated factors for IL-10 levels.

CONCLUSION

The inflammatory responses were associated with the distress in family caregiving for cancer patients. Thus, interventions are needed to support caregivers and manage their caregiving distress.

The tyrosine phosphatase SHP2 increases robustness and information transfer within IL-6-induced JAK/STAT signalling

Background

Cell-to-cell heterogeneity is an inherent feature of multicellular organisms and is central in all physiological and pathophysiological processes including cellular signal transduction. The cytokine IL-6 is an essential mediator of pro- and anti-inflammatory processes. Dysregulated IL-6-induced intracellular JAK/STAT signalling is associated with severe inflammatory and proliferative diseases. Under physiological conditions JAK/STAT signalling is rigorously controlled and timely orchestrated by regulatory mechanisms such as expression of the feedback-inhibitor SOCS3 and activation of the protein-tyrosine phosphatase SHP2 (PTPN11). Interestingly, the function of negative regulators seems not to be restricted to controlling the strength and timely orchestration of IL-6-induced STAT3 activation. Exemplarily, SOCS3 increases robustness of late IL-6-induced STAT3 activation against heterogenous STAT3 expression and reduces the amount of information transferred through JAK/STAT signalling.

Methods

Here we use multiplexed single-cell analyses and information theoretic approaches to clarify whether also SHP2 contributes to robustness of STAT3 activation and whether SHP2 affects the amount of information transferred through IL-6-induced JAK/STAT signalling.

Results

SHP2 increases robustness of both basal, cytokine-independent STAT3 activation and early IL-6-induced STAT3 activation against differential STAT3 expression. However, SHP2 does not affect robustness of late IL-6-induced STAT3 activation. In contrast to SOCS3, SHP2 increases the amount of information transferred through IL-6-induced JAK/STAT signalling, probably by reducing cytokine-independent STAT3 activation and thereby increasing sensitivity of the cells. These effects are independent of SHP2-dependent MAPK activation.

Conclusion

In summary, the results of this study extend our knowledge of the functions of SHP2 in IL-6-induced JAK/STAT signalling. SHP2 is not only a repressor of basal and cytokine-induced STAT3 activity, but also ensures robustness and transmission of information.

Plain English summary Cells within a multicellular organism communicate with each other to exchange information about the environment. Communication between cells is facilitated by soluble molecules that transmit information from one cell to the other. Cytokines such as interleukin-6 are important soluble mediators that are secreted when an organism is faced with infections or inflammation. Secreted cytokines bind to receptors within the membrane of their target cells. This binding induces activation of an intracellular cascade of reactions called signal transduction, which leads to cellular responses. An important example of intracellular signal transduction is JAK/STAT signalling. In healthy organisms signalling is controlled and timed by regulatory mechanisms, whose activation results in a controlled shutdown of signalling pathways. Interestingly, not all cells within an organism are identical. They differ in the amount of proteins involved in signal transduction, such as STAT3. These differences shape cellular communication and responses to intracellular signalling. Here, we show that an important negative regulatory protein called SHP2 (or PTPN11) is not only responsible for shutting down signalling, but also for steering signalling in heterogeneous cell populations. SHP2 increases robustness of STAT3 activation against variable STAT3 amounts in individual cells. Additionally, it increases the amount of information transferred through JAK/STAT signalling by increasing the dynamic range of pathway activation in heterogeneous cell populations. This is an amazing new function of negative regulatory proteins that contributes to communication in heterogeneous multicellular organisms in health and disease.

SOCS: negative regulators of cytokine signaling for immune tolerance

Cytokines are important intercellular communication tools for immunity. Many cytokines promote gene transcription and proliferation through the JAK/STAT (Janus kinase / signal transducers and activators of transcription) and the Ras/ERK (GDP/GTP-binding rat sarcoma protein / extracellular signal-regulated kinase) pathways, and these signaling pathways are tightly regulated. The SOCS (suppressor of cytokine signaling) family are representative negative regulators of JAK/STAT-mediated cytokine signaling and regulate the differentiation and function of T cells, thus being involved in immune tolerance. Human genetic analysis has shown that SOCS family members are strongly associated with autoimmune diseases, allergy and tumorigenesis. SOCS family proteins also function as immune-checkpoint molecules that contribute to the unresponsiveness of T cells to cytokines.

[Myokines and adipomyokines: inflammatory mediators or unique molecules of targeted therapy for obesity?]

Skeletal muscles make up about 25% of the total mass in children and more than 40% in adults. Studies of the last twenty years have shown that along with the main functions, muscle tissue has hormonal activity. It was found that myocytes are able to release signaling molecules-myokines. They act auto-and paracrine within the muscle, and at a high level-through the systemic circulation, carrying out interactions between skeletal muscles and various organs and tissues, such as the liver, bone and adipose tissue, the brain. It is proved that the key factor in the expression of myokines is physical activity, and their level largely depends on physical fitness, the amount of skeletal muscle mass and its composition (the ratio of fast and slow fibers), on the intensity and duration of physical activity. Myokines have a wide range of physiological effects: myostatin suppresses the growth and differentiation of muscle tissue, and decorin, acting as its antagonist, promotes muscle hypertrophy. Interleukin 6 provides an energy substrate for contracting muscle fibers, fibroblast growth factor 21 activates the mechanisms of energy production during fasting and improves tissue sensitivity to insulin; irisin stimulates thermogenesis, glucose uptake by myocytes, and also contributes to an increase in bone mineral density. The study of myokines is one of the key links in understanding the mechanisms underlying obesity and metabolic complications, the consequences of a sedentary lifestyle, as well as the implementation of the action of physical activity. Taking into account the physiological effects of myokines in the body, in the future they can become therapeutic targets for the treatment of these conditions.

4-Phenylbutyric acid improves free fatty acid-induced hepatic insulin resistance in vivo

Plasma free fatty acids (FFAs) are elevated in obesity and can induce insulin resistance via endoplasmic reticulum (ER) stress. However, it is unknown whether hepatic insulin resistance caused by the elevation of plasma FFAs is alleviated by chemical chaperones. Rats received one of the following i.v. treatments for 48 h: saline, intralipid plus heparin (IH), IH plus the chemical chaperone 4-phenylbutyric acid (PBA), or PBA alone and a hyperinsulinemic-euglycemic clamp was performed during the last 2 h. PBA co-infusion normalized IH-induced peripheral insulin resistance, similar to our previous findings with an antioxidant and an IκBα kinase β (IKKβ) inhibitor. Different from our previous results with the antioxidant and IKKβ inhibitor, PBA also improved IH-induced hepatic insulin resistance in parallel with activation of Akt. Unexpectedly, IH did not induce markers of ER stress in the liver, but PBA prevented IH-induced elevation of phosphorylated eukaryotic initiation factor-2α protein in adipose tissue. PBA tended to decrease circulating fetuin-A and significantly increased circulating fibroblast growth factor 21 (FGF21) without affecting markers of activation of hepatic protein kinase C-δ or p38 mitogen-activated protein kinase that we have previously involved in hepatic insulin resistance in this model. In conclusion: (i) PBA prevented hepatic insulin resistance caused by prolonged plasma FFA elevation without affecting hepatic ER stress markers; (ii) the PBA effect is likely due to increased FGF21 and/or decreased fetuin-A, which directly signal to upregulate Akt activation.

Inhibitory feedback control of NF-κB signalling in health and disease

Cells must adapt to changes in their environment to maintain cell, tissue and organismal integrity in the face of mechanical, chemical or microbiological stress. Nuclear factor-κB (NF-κB) is one of the most important transcription factors that controls inducible gene expression as cells attempt to restore homeostasis. It plays critical roles in the immune system, from acute inflammation to the development of secondary lymphoid organs, and also has roles in cell survival, proliferation and differentiation. Given its role in such critical processes, NF-κB signalling must be subject to strict spatiotemporal control to ensure measured and context-specific cellular responses. Indeed, deregulation of NF-κB signalling can result in debilitating and even lethal inflammation and also underpins some forms of cancer. In this review, we describe the homeostatic feedback mechanisms that limit and ‘re-set’ inducible activation of NF-κB. We first describe the key components of the signalling pathways leading to activation of NF-κB, including the prominent role of protein phosphorylation and protein ubiquitylation, before briefly introducing the key features of feedback control mechanisms. We then describe the array of negative feedback loops targeting different components of the NF-κB signalling cascade including controls at the receptor level, post-receptor signalosome complexes, direct regulation of the critical ‘inhibitor of κB kinases’ (IKKs) and inhibitory feedforward regulation of NF-κB-dependent transcriptional responses. We also review post-transcriptional feedback controls affecting RNA stability and translation. Finally, we describe the deregulation of these feedback controls in human disease and consider how feedback may be a challenge to the efficacy of inhibitors.

Stat3 loss in mesenchymal progenitors causes Job syndrome-like skeletal defects by reducing Wnt/β-catenin signaling

Job syndrome is a rare genetic disorder caused by STAT3 mutations and primarily characterized by immune dysfunction along with comorbid skeleton developmental abnormalities including osteopenia, recurrent fracture of long bones, and scoliosis. So far, there is no definitive cure for the skeletal defects in Job syndrome, and treatments are limited to management of clinical symptoms only. Here, we have investigated the molecular mechanism whereby Stat3 regulates skeletal development and osteoblast differentiation. We showed that removing Stat3 function in the developing limb mesenchyme or osteoprogenitor cells in mice resulted in shortened and bow limbs with multiple fractures in long bones that resembled the skeleton symptoms in the Job Syndrome. However, Stat3 loss did not alter chondrocyte differentiation and hypertrophy in embryonic development, while osteoblast differentiation was severely reduced. Genome-wide transcriptome analyses as well as biochemical and histological studies showed that Stat3 loss resulted in down-regulation of Wnt/β-catenin signaling. Restoration of Wnt/β-catenin signaling by injecting BIO, a small molecule inhibitor of GSK3, or crossing with a Lrp5 gain of function (GOF) allele, rescued the bone reduction phenotypes due to Stat3 loss to a great extent. These studies uncover the essential functions of Stat3 in maintaining Wnt/β-catenin signaling in early mesenchymal or osteoprogenitor cells and provide evidence that bone defects in the Job Syndrome are likely caused by Wnt/β-catenin signaling reduction due to reduced STAT3 activities in bone development. Enhancing Wnt/β-catenin signaling could be a therapeutic approach to reduce bone symptoms of Job syndrome patients.

Cyanocobalamin prevents cardiomyopathy in type 1 diabetes by modulating oxidative stress and DNMT-SOCS1/3-IGF-1 signaling

Patients with long-standing diabetes have a high risk for cardiac complications that is exacerbated by increased reactive oxygen species (ROS) production. We found that feeding cyanocobalamin (B12), a scavenger of superoxide, not only prevented but reversed signs of cardiomyopathy in type 1 diabetic Elmo1^H/H Ins2^Akita/+ mice. ROS reductions in plasma and hearts were comparable to those in mice treated with other antioxidants, N-acetyl-L-cysteine or tempol, but B12 produced better cardioprotective effects. Diabetes markedly decreased plasma insulin-like growth factor (IGF)-1 levels, while B12, but not N-acetyl-L-cysteine nor tempol, restored them. B12 activated hepatic IGF-1 production via normalization of S-adenosylmethionine levels, DNA methyltransferase (DNMT)-1/3a/3b mRNA, and DNA methylation of promoters for suppressor of cytokine signaling (SOCS)-1/3. Reductions of cardiac IGF-1 mRNA and phosphorylated IGF-1 receptors were also restored. Thus, B12 is a promising option for preventing diabetic cardiomyopathy via ROS reduction and IGF-1 retrieval through DNMT-SOCS1/3 signaling.

Dissecting the molecular control of Interleukin 6 signaling using the M1 cell line

Interleukin 6 is the classical member of the IL-6 family of cytokines which triggers activation of the JAK/STAT signaling cascade in cells. IL-6 is a pleiotropic cytokine that acts on many cell types and plays a critical role in immune responses, inflammation, and haematopoiesis. Our understanding of the molecular mechanisms governing IL-6 signaling has been aided by numerous studies of this signal transduction pathway, including those utilising the M1 cell line. Here we discuss the studies that we and others have undertaken using the M1 line to examine IL-6 inducible genes, particularly those targets that acts as negative regulators of signaling. Finally, we present a model for the current understanding of the IL-6 signaling pathway at a structural and mechanistic level.

Inhibitory Effect of Lipoteichoic Acid Derived from Three Lactobacilli on Flagellin-Induced IL-8 Production in Porcine Peripheral Blood Mononuclear Cells

Probiotics in livestock feed supplements are considered to be an alternative to antibiotics. However, effector molecules responsible for the beneficial roles of probiotics in pigs are in general not well known. Thus, this study demonstrated that a well-known virulence factor, flagellin of Salmonella typhimurium, significantly induced IL-8 production in porcine peripheral blood mononuclear cells, whereas lipoteichoic acid (LTA), a major cell wall component of Gram-positive bacteria Lactobacillus plantarum, L. casei, and L. rhamnosus GG, effectively inhibited flagellin-induced IL-8 production at mRNA and protein levels. However, the lipoproteins of L. plantarum, L. casei, and L. rhamnosus GG did not suppress flagellin-induced IL-8 production. While D-alanine-deficient L. plantarum LTA inhibited flagellin-induced IL-8 production, L. plantarum LTA deficient in both D-alanine and acyl chains failed to inhibit it; this suggests that the acyl moieties of L. plantarum LTA are essential for inhibiting flagellin-induced IL-8 production. Taken together, L. plantarum LTA plays an important role in improving anti-inflammatory responses of porcine peripheral blood mononuclear cells.

UBX Domain Protein 6 Positively Regulates JAK-STAT1/2 Signaling

Type I/III IFNs induce expression of hundreds of IFN-stimulated genes through the JAK/STAT pathway to combat viral infections. Although JAK/STAT signaling is seemingly straightforward, it is nevertheless subjected to complex cellular regulation. In this study, we show that an ubiquitination regulatory X (UBX) domain-containing protein, UBXN6, positively regulates JAK-STAT1/2 signaling. Overexpression of UBXN6 enhanced type I/III IFNs-induced expression of IFN-stimulated genes, whereas deletion of UBXN6 inhibited their expression. RNA viral replication was increased in human UBXN6-deficient cells, accompanied by a reduction in both type I/III IFN expression, when compared with UBXN6-sufficient cells. Mechanistically, UBXN6 interacted with tyrosine kinase 2 (TYK2) and inhibited IFN-β-induced degradation of both TYK2 and type I IFNR. These results suggest that UBXN6 maintains normal JAK-STAT1/2 signaling by stabilizing key signaling components during viral infection.

Rab40-Cullin5 complex regulates EPLIN and actin cytoskeleton dynamics during cell migration

Rab40b is a SOCS box–containing protein that regulates the secretion of MMPs to facilitate extracellular matrix remodeling during cell migration. Here, we show that Rab40b interacts with Cullin5 via the Rab40b SOCS domain. We demonstrate that loss of Rab40b–Cullin5 binding decreases cell motility and invasive potential and show that defective cell migration and invasion stem from alteration to the actin cytoskeleton, leading to decreased invadopodia formation, decreased actin dynamics at the leading edge, and an increase in stress fibers. We also show that these stress fibers anchor at less dynamic, more stable focal adhesions. Mechanistically, changes in the cytoskeleton and focal adhesion dynamics are mediated in part by EPLIN, which we demonstrate to be a binding partner of Rab40b and a target for Rab40b–Cullin5-dependent localized ubiquitylation and degradation. Thus, we propose a model where Rab40b–Cullin5-dependent ubiquitylation regulates EPLIN localization to promote cell migration and invasion by altering focal adhesion and cytoskeletal dynamics.

UFMylation inhibits the proinflammatory capacity of interferon-γ-activated macrophages

Macrophages activated with interferon-γ (IFN-γ) in combination with other proinflammatory stimuli, such as lipopolysaccharide or tumor necrosis factor-α (TNF-α), respond with transcriptional and cellular changes that enhance clearance of intracellular pathogens at the risk of damaging tissues. IFN-γ effects must therefore be carefully balanced with inhibitory mechanisms to prevent immunopathology. We performed a genome-wide CRISPR knockout screen in a macrophage cell line to identify negative regulators of IFN-γ responses. We discovered an unexpected role of the ubiquitin-fold modifier (Ufm1) conjugation system (herein UFMylation) in inhibiting responses to IFN-γ and lipopolysaccharide. Enhanced IFN-γ activation in UFMylation-deficient cells resulted in increased transcriptional responses to IFN-γ in a manner dependent on endoplasmic reticulum stress responses involving Ern1 and Xbp1. Furthermore, UFMylation in myeloid cells is required for resistance to influenza infection in mice, indicating that this pathway modulates in vivo responses to infection. These findings provide a genetic roadmap for the regulation of responses to a key mediator of cellular immunity and identify a molecular link between the UFMylation pathway and immune responses.

A new reliable and highly specific monoclonal antibody to detect the C-terminal region of silencer of cytokine signaling 1

INTRODUCTION

SOCS1, a negative regulator of JAK/STAT signaling, is among the most frequently mutated genes in DLBCL and classical Hodgkin lymphoma. The C-terminal SOCS box domain, mediating the degradation of phospho-JAK2, is often affected or even lacking. The analysis of such variants is hampered by the lack of a SOCS1-specific monoclonal antibody recognizing the C-terminus of SOCS1. As this C-terminus is often lost or mutated in B-cell lymphomas, staining with amino-terminal targeting antibodies in a lymphoma setting might be misleading.

METHODS

BALB/c mice were immunized with a truncated SOCS1 C-terminal protein. The supernatant of generated hybridoma cells was screened by ELISA and, immunohistochemically, on formalin-fixed and paraffin-embedded tonsil. After antibody purification by affinity chromatography, epitope mapping and cross-reactivity check followed via substitution scans. SOCS1 protein expression was investigated on cell cultures and cytoblocks of SOCS1_WT stably transfected HEK293T cells, lymphoma cell lines and lymphoid tissues.

RESULTS

Procedures resulted in one monoclonal IgG1 anti-SOCS1 antibody, 424C, that recognizes and strongly binds to the C-terminal region of SOCS1 in immunoblot and immunohistochemistry analyses.

CONCLUSION

This new anti-SOCS1 monoclonal antibody is a valuable tool to detect SOCS1 expression dependent on an existing SOCS1 box and, therefore, indicating a full-length SOCS1 protein.

Uveitis: Molecular Pathogenesis and Emerging Therapies

The profound impact that vision loss has on human activities and quality of life necessitates understanding the etiology of potentially blinding diseases and their clinical management. The unique anatomic features of the eye and its sequestration from peripheral immune system also provides a framework for studying other diseases in immune privileged sites and validating basic immunological principles. Thus, early studies of intraocular inflammatory diseases (uveitis) were at the forefront of research on organ transplantation. These studies laid the groundwork for foundational discoveries on how immune system distinguishes self from non-self and established current concepts of acquired immune tolerance and autoimmunity. Our charge in this review is to examine how advances in molecular cell biology and immunology over the past 3 decades have contributed to the understanding of mechanisms that underlie immunopathogenesis of uveitis. Particular emphasis is on how advances in biotechnology have been leveraged in developing biologics and cell-based immunotherapies for uveitis and other neuroinflammatory diseases.

Suppressor of cytokine signaling 2 is induced in Huntington's disease and involved in autophagy

Suppressor of cytokine signaling (SOCS) proteins are primarily feedback inhibitors of cytokine signaling. The two conserved domains of SOCS proteins have distinct functions. Src homology 2 (SH2) domain inhibits cytokine receptor, while SOCS box acts as an E3 ubiquitin ligase. SOCS2, a cytokine signaling suppressor, has been primarily implicated in regulating inflammatory conditions in neuronal diseases. However, SOCS proteins have been suggested to play diverse roles in healthy and diseased nervous system including neurodegenerative disorders. In this study, SOCS2 was found to be upregulated in Huntington's disease and was substantially induced in extended polyglutamine (polyQ)-expressing striatal cells. The induced level was augmented under aging conditions. In extended polyQ-expressing cells, downregulated SOCS2 improved autophagic dysfunction rather than altered inflammatory conditions. Overall, we suggest that SOCS2 involves in regulating autophagy by functioning as an E3 ligase in extended polyQ conditions, and consequently regulates cell damage and cell death type.

People with HIV-1 demonstrate type 1 interferon refractoriness associated with upregulated USP18

HIV-1 infection persists in humans despite expression of antiviral type 1 interferons (IFN). Even exogenous administration of IFNα only marginally reduces HIV-1 abundance, raising the hypothesis that people living with HIV-1 (PLWH) are refractory to type 1 IFN. We demonstrated type 1 IFN refractoriness in CD4+ and CD8+ T cells isolated from HIV-1 infected persons by detecting diminished STAT1 phosphorylation (pSTAT1) and interferon-stimulated gene (ISG) induction upon type 1 IFN stimulation compared to healthy controls. Importantly, HIV-1 infected people who were virologically suppressed with antiretrovirals also showed type 1 IFN refractoriness. We found that USP18 levels were elevated in people with refractory pSTAT1 and ISG induction and confirmed this finding ex vivo in CD4+ T cells from another cohort of HIV-HCV coinfected persons who received exogenous pegylated interferon-α2b in a clinical trial. We used a cell culture model to recapitulate type 1 IFN refractoriness in uninfected CD4+ T cells that were conditioned with media from HIV-1 inoculated PBMCs, inhibiting de novo infection with antiretroviral agents. In this model, RNA interference against USP18 partly restored type 1 IFN responses in CD4+ T cells. We found evidence of type 1 IFN refractoriness in PLWH irrespective of virologic suppression that was associated with upregulated USP18, a process that might be therapeutically targeted to improve endogenous control of infection.ImportancePeople living with HIV-1 (PLWH) have elevated constitutive expression of type 1 interferons (IFN). However, it is unclear whether this impacts downstream innate immune responses. We identified refractory responses to type 1 IFN stimulation in T cells from PLWH, independent of antiretroviral treatment. Type 1 IFN refractoriness was linked to elevated USP18 levels in the same cells. Moreover, we found that USP18 levels predicted the anti-HIV-1 effect of type 1 IFN-based therapy on PLWH. In vitro, we demonstrated that refractory type 1 IFN responses were transferrable to HIV-1 uninfected target CD4+ T cells, and this phenomenon was mediated by type 1 IFN from HIV-1 infected cells. Type 1 IFN responses were partially restored by USP18 knockdown. Our findings illuminate a new mechanism by which HIV-1 contributes to innate immune dysfunction in PLWH, through the continuous production of type 1 IFN that induces a refractory state of responsiveness.

The role of SOCS proteins in the development of virus- induced hepatocellular carcinoma

Background

Liver cancer has become one of the most common cancers and has a high mortality rate. Hepatocellular carcinoma is one of the most common liver cancers, and its occurrence and development process are associated with chronic hepatitis B virus (HBV) and hepatitis C virus (HCV) infections.

Main body

The serious consequences of chronic hepatitis virus infections are related to the viral invasion strategy. Furthermore, the viral escape mechanism has evolved during long-term struggles with the host. Studies have increasingly shown that suppressor of cytokine signaling (SOCS) proteins participate in the viral escape process. SOCS proteins play an important role in regulating cytokine signaling, particularly the Janus kinase-signal transducer and activator of transcription (JAK-STAT) signaling pathway. Cytokines stimulate the expression of SOCS proteins, in turn, SOCS proteins inhibit cytokine signaling by blocking the JAK-STAT signaling pathway, thereby achieving homeostasis. By utilizing SOCS proteins, chronic hepatitis virus infection may destroy the host’s antiviral responses to achieve persistent infection.

Conclusions

This review provides recent knowledge regarding the role of SOCS proteins during chronic hepatitis virus infection and provides some new ideas for the future treatment of chronic hepatitis.

Microtubule-dependent mechanism of anti-inflammatory effect of SOCS1 in endothelial dysfunction and lung injury

Suppressors of cytokine signaling (SOCS) provide negative regulation of inflammatory reaction. The role and precise cellular mechanisms of SOCS1 in control of endothelial dysfunction and barrier compromise associated with acute lung injury remain unexplored. Our results show that siRNA-mediated SOCS1 knockdown augmented lipopolysaccharide (LPS)-induced pulmonary endothelial cell (EC) permeability and enhanced inflammatory response. Consistent with in vitro data, EC-specific SOCS1 knockout mice developed more severe lung vascular leak and accumulation of inflammatory cells in bronchoalveolar lavage fluid. SOCS1 overexpression exhibited protective effects against LPS-induced endothelial permeability and inflammation, which were dependent on microtubule (MT) integrity. Biochemical and image analysis of unstimulated EC showed SOCS1 association with the MT, while challenge with LPS or MT depolymerizing agent colchicine impaired this association. SOCS1 directly interacted with N2 domains of MT-associated proteins CLIP-170 and CLASP2. Furthermore, N-terminal region of SOCS1 was indispensable for these interactions and SOCS1-ΔN mutant lacking N-terminal 59 amino acids failed to rescue LPS-induced endothelial dysfunction. Depletion of endogenous CLIP-170 or CLASP2 abolished SOCS1 interaction with Toll-like receptor-4 and Janus kinase-2 leading to impairment of SOCS1 inhibitory effects on LPS-induced inflammation. Altogether, these findings suggest that endothelial barrier protective and anti-inflammatory effects of SOCS1 are critically dependent on its targeting to the MT.

Multi-omics links IL-6 trans-signalling with neutrophil extracellular trap formation and Haemophilus infection in COPD

BACKGROUND

IL-6 trans-signalling (IL-6TS) is emerging as a pathogenic mechanism in chronic respiratory diseases, however the drivers of IL-6TS in the airways and the phenotypic characteristic of patients with increased IL-6TS pathway activation remain poorly understood.

OBJECTIVE

Our aim was to identify and characterize COPD patients with increased airway IL-6TS and to elucidate the biological drivers of IL-6TS pathway activation.

METHODS

We used an IL-6TS-specific sputum biomarker profile (sIL-6R, IL-6, IL-1β, IL-8, MIP-1β) to stratify sputum data from patients with COPD (n=74; BEAT-COPD) by hierarchical clustering. The IL-6TS signature was related to clinical characteristics and sputum microbiome profiles. The induction of neutrophil extracellular trap formation (NETosis) and IL-6TS by Haemophilus influenzae were studied in human neutrophils.

RESULTS

Hierarchical clustering revealed an IL-6TS-high subset (n=24) of COPD patients, which shared phenotypic traits with an IL-6TS-high subset previously identified in asthma. The subset was characterized by increased sputum cell counts (p=0.0001), persistent sputum neutrophilia (p=0.0004), reduced quality of life (CRQ total score; p=0.008), and increased levels of pro-inflammatory mediators and MMPs in sputum. IL-6TS-high COPD patients showed an increase in Proteobacteria, with Haemophilus as the dominating genus. NETosis induced by H. influenzae was identified as a potential mechanism for increased soluble IL-6 receptor (sIL-6R) levels. This was supported by a significant positive correlation between sIL-6R and NETosis markers in bronchoalveolar lavage fluid from COPD patients.

CONCLUSION

IL-6TS pathway activation due to chronic colonization with Haemophilus may be an important disease driver in a subset of COPD patients.