SOCS1, a Negative Regulator of Cytokine Signals and TLR Responses, in Human Liver Diseases

An herbal formulation "Shugan Xiaozhi decoction" ameliorates methionine/choline deficiency-induced nonalcoholic steatohepatitis through regulating inflammation and apoptosis-related pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Shugan Xiaozhi (SGXZ) decoction is a traditional Chinese medicine used for treating nonalcoholic steatohepatitis (NASH). It has been used clinically for over 20 years and proved to be effective; however, the molecular mechanism underlying the effects of SGXZ decoction remains unclear.

AIM OF THE STUDY

We analyzed the chemical components, core targets, and molecular mechanisms of SGXZ decoction to improve NASH through network pharmacology and in vivo experiments.

MATERIALS AND METHODS

The chemical components, core targets, and related signaling pathways of SGXZ decoction intervention in NASH were predicted using network pharmacology. Molecular docking was performed to verify chemical components and their core targets. The results were validated in the NASH model treated with SGXZ decoction. Mouse liver function was assessed by measuring ALT and AST levels. TC and TG levels were determined to evaluate lipid metabolism, and lipid deposition was assessed via oil red O staining. Mouse liver damage was determined via microscopy following hematoxylin and eosin staining. Liver fibrosis was assessed via Masson staining. Western blot (WB) and immunohistochemical (IHC) analyses were performed to detect inflammation and the expression of apoptosis-related proteins, including IL-1β, IL-6, IL-18, TNF-α, MCP1, p53, FAS, Caspase-8, Caspase-3, Caspase-9, Bax, Bid, Cytochrome c, Bcl-2, and Bcl-XL. In addition, WB and IHC were used to assess protein expression associated with the TLR4/MyD88/NF-κB pathway.

RESULTS

Quercetin, luteolin, kaempferol, naringenin, and nobiletin in SGXZ decoction were effective chemical components in improving NASH, and TNF-α, IL-6, and IL-1β were the major core targets. Molecular docking indicated that these chemical components and major core targets might interact. KEGG pathway analysis showed that the pathways affected by SGXZ decoction, primarily including apoptosis and TLR4/NF-κB signaling pathways, interfere with NASH. In vivo experiments indicated that SGXZ decoction considerably ameliorated liver damage, fibrosis, and lipid metabolism disorder in MCD-induced NASH mouse models. In addition, WB and IHC verified the underlying molecular mechanisms of SGXZ decoction as predicted via network pharmacology. SGXZ decoction inhibited the activation of apoptosis-related pathways in MCD-induced NASH mice. Moreover, SGXZ decoction suppressed the activation of TLR4/MyD88/NF-κB pathway in MCD-induced NASH mice.

CONCLUSION

SGXZ decoction can treat NASH through multiple targets and pathways. These findings provide new insights into the effective treatment of NASH using SGXZ decoction.

The Interplay Between Helicobacter pylori and Suppressors of Cytokine Signaling (SOCS) Molecules in the Development of Gastric Cancer and Induction of Immune Response

Helicobacter pylori (H. pylori) colonizes the stomach and leads to the secretion of a vast range of cytokines by infiltrated leukocytes directing immune/inflammatory response against the bacterium. To regulate immune/inflammatory responses, suppressors of cytokine signaling (SOCS) proteins bind to multiple signaling components located downstream of cytokine receptors, such as Janus kinase (JAK), signal transducers and activators of transcription (STAT). Dysfunctional SOCS proteins in immune cells may facilitate the immune evasion of H. pylori, allowing the bacteria to induce chronic inflammation. Dysregulation of SOCS expression and function can contribute to the sustained H. pylori-mediated gastric inflammation which can lead to gastric cancer (GC) development. Among SOCS molecules, dysregulated expression of SOCS1, SOCS2, SOCS3, and SOCS6 were indicated in H. pylori-infected individuals as well as in GC tissues and cells. H. pylori-induced SOCS1, SOCS2, SOCS3, and SOCS6 dysregulation can contribute to the GC development. The expression of SOCS molecules can be influenced by various factors, such as epigenetic DNA methylation, noncoding RNAs, and gene polymorphisms. Modulation of the expression of SOCS molecules in gastric epithelial cells and immune cells can be considered to control gastric carcinogenesis as well as regulate antitumor immune responses, respectively. This review aimed to explain the interplay between H. pylori and SOCS molecules in GC development and immune response induction as well as to provide insights regarding potential therapeutic strategies modulating SOCS molecules.

Aberrant expression of SOCS impairs the anti-leishmanial immune response

Establishing a balance between Th1 and Th2 subsets and M1- and M2-type macrophages is essential for the control of Leishmania infection. The suppressors of cytokine secretion (SOCS) proteins, particularly SOCS1 and SOCS3, play a significant role in regulating cytokine-triggered signaling pathways, thereby impacting the macrophage-and effector T-cell mediated antileishmanial immune response. In addition to the pro-inflammatory cytokines, Leishmania-derived lipophosphoglycan (LPG) and CpG-DNA interact with TLR2 and TLR9 to trigger SOCS expression. The aberrant levels of SOCS1 and SOCS3 expression in Leishmania-infected macrophages impair macrophage-T-cell interaction perturbing the balance in macrophage subsets polarization. This hinders macrophage apoptosis and macrophage-mediated leishmanicidal activity, both support the establishment of infection and parasite replication. Furthermore, aberrant SOCS3 levels in T-cells disrupt Th1 differentiation and aid in parasite replication, lesion development, and pathological immune responses. Strategically, selective modulation of SOCS expression and function in immune effector cells may reduce parasite survival and prevent disease progression.

Exploring TLR signaling pathways as promising targets in cervical cancer: The road less traveled

Cervical cancer is the leading cause of cancer-related deaths for women globally. Despite notable advancements in prevention and treatment, the identification of novel therapeutic targets remains crucial for cervical cancer. Toll-like receptors (TLRs) play an essential role in innate immunity as pattern-recognition receptors. There are several types of pathogen-associated molecular patterns (PAMPs), including those present in cervical cancer cells, which have the ability to activate toll-like receptors (TLRs). Recent studies have revealed dysregulated toll-like receptor (TLR) signaling pathways in cervical cancer, leading to the production of inflammatory cytokines and chemokines that can facilitate tumor growth and metastasis. Consequently, TLRs hold significant promise as potential targets for innovative therapeutic agents against cervical cancer. This book chapter explores the role of TLR signaling pathways in cervical cancer, highlighting their potential for targeted therapy while addressing challenges such as tumor heterogeneity and off-target effects. Despite these obstacles, targeting TLR signaling pathways presents a promising approach for the development of novel and effective treatments for cervical cancer.

The Tumor Suppressor SOCS1 Diminishes Tolerance to Oxidative Stress in Hepatocellular Carcinoma

SOCS1 is a tumor suppressor in hepatocellular carcinoma (HCC). Recently, we showed that a loss of SOCS1 in hepatocytes promotes NRF2 activation. Here, we investigated how SOCS1 expression in HCC cells affected oxidative stress response and modulated the cellular proteome. Murine Hepa1-6 cells expressing SOCS1 (Hepa-SOCS1) or control vector (Hepa-Vector) were treated with cisplatin or tert-butyl hydroperoxide (t-BHP). The induction of NRF2 and its target genes, oxidative stress, lipid peroxidation, cell survival and cellular proteome profiles were evaluated. NRF2 induction was significantly reduced in Hepa-SOCS1 cells. The gene and protein expression of NRF2 targets were differentially induced in Hepa-Vector cells but markedly suppressed in Hepa-SOCS1 cells. Hepa-SOCS1 cells displayed an increased induction of reactive oxygen species but reduced lipid peroxidation. Nonetheless, Hepa-SOCS1 cells treated with cisplatin or t-BHP showed reduced survival. GCLC, poorly induced in Hepa-SOCS1 cells, showed a strong positive correlation with NFE2L2 and an inverse correlation with SOCS1 in the TCGA-LIHC transcriptomic data. A proteomic analysis of Hepa-Vector and Hepa-SOCS1 cells revealed that SOCS1 differentially modulated many proteins involved in diverse molecular pathways, including mitochondrial ROS generation and ROS detoxification, through peroxiredoxin and thioredoxin systems. Our findings indicate that maintaining sensitivity to oxidative stress is an important tumor suppression mechanism of SOCS1 in HCC.

Prediction of the mechanisms of action of Qutan Huoxue decoction in non-alcoholic steatohepatitis (NASH): a network pharmacology study and experimental validation

CONTEXT

Qutan Huoxue decoction (QTHX) is used to treat non-alcoholic steatohepatitis (NASH) with good efficacy in the clinic. However, the mechanism is not clear yet.

OBJECTIVE

This study investigates the mechanism of QTHX in the treatment of NASH.

MATERIALS AND METHODS

Potential pathways of QTHX were predicted by network pharmacology. Fourty Sprague Dawley (SD) rats (half normal diet, half high-fat diet) were fed six to eight weeks, primary hepatocytes and Kupffer cells were extracted and co-cultured by the 0.4-micron trans well culture system. Then, the normal co-cultured cells were treated by normal serum, the NASH co-cultured cells were treated with various concentrations of QTHX-containing serum (0, 5, 7.5 or 10 μg/mL) for 24 h. The expression of targets were measured with Activity Fluorometric Assay, Western blot and PCR assay.

RESULTS

Network pharmacology indicated that liver-protective effect of QTHX was associated with its anti-inflammation response, oxidative stress, and lipid receptor signalling. 10 μg/mL QTHX significantly reduced the inflammation response and lipid levels in primary hepatocytes (ALT: 46.43 ± 2.76 U/L, AST: 13.96 ± 1.08 U/L, TG: 0.25 ± 0.01 mmol/L, TC: 0.14 ± 0.05 mmol/L), comparing with 0 μg/mL NASH group (ALT: 148 ± 9.22 U/L, AST: 53.02 ± 2.30 U/L, TG: 0.74 ± 0.07 mmol/L, TC: 0.91 ± 0.07 mmol/L) (p < 0.01). Meanwhile, QTHX increased expression of SOCS1 and decreased expression of TLR4, Myd88, NF-κB.

CONCLUSIONS

The study suggested that QTHX treats NASH in rats by activating the SCOS1/NF-κB/TLR4 pathway, suggesting QTHX could be further developed as a potential liver-protecting agent.

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.

The role of miRNA-26a-5p and target gene socs1a in flutolanil induced hepatotoxicity of zebrafish at environmental relevant levels

Flutolanil has been detected worldwide in aquatic environment and fish, which has become an undeniable stressor on ecosystem and human health. Flutolanil has been reported to be toxic to aquatic organisms. However, the pathophysiological and molecular mechanism behind the detrimental effects remains obscure. Here we reported hepatotoxicity induced by flutolanil in HepG2 cells and zebrafish, as revealed by toxicokinetic, HE staining, miRNAs-mRNAs sequencing, molecular dynamic simulations and dual luciferase reporter assays. Collectively, our results indicated that flutolanil could be absorbed by and accumulated in the liver of zebrafish, causing hepatic vacuolar degeneration, steatosis and nuclear condensation and abnormal liver function, where its exposure at environmental levels disrupted the expressions of miRNA-26a-5p and its target gene socs1a by mediating JAK-STAT signaling pathway, which was partially responsible for hepatotoxicity, correlated with oxidative stress, cell apoptosis, inflammation, cell cycle disorder and mitochondrial dysfunction. These findings suggest that miRNA-26a-5p/socs1a can serve as potential biomarkers of hepatotoxicity in zebrafish following exposure to flutolanil. This uncovered route will provide a new tool for the risk assessment of flutolanil and a guide to proper use of flutolanil and environmental remedy, and open up a new horizon for liver disease assessment.

Molecular characterization and immune response of suppressor of cytokine signaling 5b from redlip mullet (Planiliza haematocheilus): Disclosing its anti-viral potential and effect on cell proliferation

The suppressor of cytokine signaling (SOCS) proteins family comprising eight proteins (SOCS1-7 and cytokine-inducible SH2-containing (CIS)) are classical feedback inhibitors of cytokine signaling. Although the biological role of CIS and SOCS1-3 have been extensively studied, the biological functions of SOCS4-7 remain unclear. Here, we elucidated the molecular characteristics, expression profile, immune response, anti-viral potential, and effect on cell proliferation of Phsocs5b, a member of the SOCS protein family from redlip mullet (Planiliza haematocheilus); phsocs5b comprised 1695 nucleotides. It was 564 amino acids long with a molecular weight of 62.3 kDa and a theoretical isoelectric point of 8.95. Like SOCS4-7 proteins, Phsocs5b comprised an SH2 domain, SOCS box domain, and a long N-terminal. SH2 domain is highly identical to its orthologs in other vertebrates. Phsocs5b, highly expressed in the brain tissue, was localized in the cytoplasm. Temporal changes in phsocs5b expression were observed following immune stimulation with polyinosinic: polycytidylic acid, lipopolysaccharide, and Lactococcus garvieae. In FHM cells, Phsocs5b overexpression suppressed the viral hemorrhagic septicemia virus (VHSV) infection and epidermal growth factor receptor (egfr) expression but increased the mRNA levels of pi3k, akt, pro-inflammatory cytokines (il1β and il8), and anti-viral genes (isg15 and ifn). Overall, our findings suggest that Phsocs5b attenuates VHSV infection, either by hindering the cell entry via degradation of Egfr, enhancing pro-inflammatory cytokines and anti-viral factor production, or both. The results also indicated that Phsocs5b could directly activate Pi3k/Akt pathway by itself, thus enhancing the proliferation and migration of cells. Taken together, Phsocs5b may be considered a potential therapeutic target to enhance immune responses while positively regulating the proliferation and migration of cells.

Enhanced Therapeutic Efficacy of Immunostimulatory CpG-ODN by Silencing SOCS-1 with Polysaccharide/miR-155 Complexes

For the induction of antigen-specific immune responses, adjuvants as well as antigens are essential. CpG-ODN is a potent agonist of toll-like receptor 9 (TLR9) and is known as an adjuvant to induce cellular immune responses. We previously developed a therapeutic oligonucleotide delivery system based on the formation of a complex between schizophyllan (SPG), a kind of β-1,3-glucan, and poly(dA), which actively delivered CpG-ODN to antigen-presenting cells (APCs) in the draining lymph nodes and induced antigen-specific immune responses. However, unfortunately, the signaling pathway of TLR9 is negatively regulated by an intracellular protein called suppressor of cytokine signaling-1 (SOCS-1), which suppresses the adjuvant effect of CpG-ODN. To solve this, we focused on microRNA-155 (miR-155), which regulates innate and autoimmune processes by targeting SOCS-1. In this study, we proposed a strategy of combining miR-155 and CpG-ODN, each complexed with SPG (denoted as SPG/miR-155 and SPG/CpG, respectively), to induce a more potent immune response. As a result, we showed that the efficient delivery of miR-155 to APCs by a complex form could induce much more potent cellular immune responses than SPG/CpG alone. Furthermore, the mice treated with the combination of SPG/miR-155 and SPG/CpG showed a long delay in tumor growth occurrence and improved survival after tumor inoculation. These results indicate the possibility of therapeutic strategies for cancer.

Transcriptome analysis of pre-immune state induced by interferon gamma inhibiting the replication of H9N2 avian influenza viruses in chicken embryo fibroblasts

Interferon (IFN), a critical antiviral cytokine produced by pathogens-induced cells, plays an important role in host innate immune system. In this study, to investigate the inhibition effect of IFN on avian influenza virus (AIV), Chicken Embryo Fibroblasts (CEFs) was infected by H₉N₂ AIV. The pre-immune state and transcriptome analysis have been observed and performed. The result showed chicken interferon gamma (chIFN-γ) have the most inhibitory effect on H₉N₂ virus among three types of chicken interferons (chIFNs). Inhibition of chIFN-γ on H₉N₂ virus was verified by indirect immunofluorescence, RT-qPCR and western blot. The possible signaling pathways induced by chIFN-γ with or without virus were analyzed by transcriptome. The transcriptome data were compared among H₉N₂-infected, chIFN-γ-treated, chIFN-γ + H₉N₂-treated, and Control groups. In summary, RNA-sequencing (RNA-seq) data suggested that H₉N₂ virus infection resulted in corresponding response of certain defensive, inflammatory and metabolism pathways to the virus replication in CEFs. Furthermore, while CEFs were treated with chIFN-γ, many immune-related signaling pathways in cells are affected and altered. Antiviral genes involved in these immune pathways such as interferon regulatory factors, chemokines, interferon-stimulated genes (ISGs) and transcription factors were significantly up-regulated, and showed significant antiviral responses. Compared with virus infected CEFs alone, pretreatment with IFN induced the expression of antiviral genes and activated related antiviral pathways, inhibited the viral replication as result. Our study provided functional annotations for antiviral genes and the basis for studying the mechanism of chIFN-γ mediated response against H₉N₂ AIV.

Inhibition of anti-inflammatory pathway through suppressors of cytokine signalling (Socs2/Socs3) in the initiation of hepatocellular carcinoma

Hepatocellular carcinoma (HCC), a leading cause of cancer related deaths is predominantly driven by chronic inflammatory responses. Due to asymptomatic nature and lack of early patient biopsies, precise involvement of inflammation in hepatic injury initiation remains unidentified. Aim of the study was to elucidate the regulation patterns of inflammatory signalling from initiation of hepatic injury to development of HCC. HCC mice model was established using DEN followed by repeated doses of CCl₄ and sacrificed at three different stages of disease comprising 7, 14 and 21 weeks. Serum biochemical tests, hepatic lipids quantification, histopathology and qPCR analyses were conducted to characterize the initiation and progression of liver injury and inflammatory signalling. Notably, at 7 weeks, we observed hepatocyte damage and periportal necrotic bodies coupled with induction of Socs2/Socs3 and anti-inflammatory cytokine Il-10. At 14 weeks, mice liver showed advancement of liver injury with micro-vesicular steatosis and moderate collagen deposition around portal zone. With progression of injury, the expression of Socs3 was declined with further reduction of Il-10 and Tgf-β indicating the disturbance of anti-inflammatory mechanism. In contrast, pro-inflammatory cytokines Il1-β, Il6 and Tnf-α were upregulated contributing inflammation. Subsequently, at 21 weeks severe liver damage was estimated as characterized by macro-vesicular steatosis, perisinusoidal collagen bridging, immune cell recruitment and significant upregulation of Col-1α and α-Sma. In parallel, there was significant upregulation of pro/anti-inflammatory cytokines highlighting the commencement of chronic inflammation.

Findings of the study suggest that differential regulation of cytokine suppressors and inflammatory cytokines might play role in the initiation and progression of hepatic injury leading towards HCC.

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.

Junin Virus Activates p38 MAPK and HSP27 Upon Entry

Junín virus (JUNV), a New World arenavirus, is a rodent-borne virus and the causative agent of Argentine hemorrhagic fever. Humans become infected through exposure to rodent host secreta and excreta and the resulting infection can lead to an acute inflammatory disease with significant morbidity and mortality. Little is understood about the molecular pathogenesis of arenavirus hemorrhagic fever infections. We utilized Reverse Phase Protein Microarrays (RPPA) to compare global alterations in the host proteome following infection with an attenuated vaccine strain, Candid#1 (CD1), and the most parental virulent strain, XJ13, of JUNV in a human cell culture line. Human small airway epithelial cells were infected with CD1 or XJ13 at an MOI of 10, or mock infected. To determine proteomic changes at early timepoints (T = 1, 3, 8 and 24 h), the JUNV infected or mock infected cells were lysed in compatible buffers for RPPA. Out of 113 proteins that were examined by RPPA, 14 proteins were significantly altered following JUNV infection. Several proteins were commonly phosphorylated between the two strains and these correspond to entry and early replication events, to include p38 mitogen-activated protein kinase (MAPK), heat shock protein 27 (HSP27), and nuclear factor kappa B (NFκB). We qualitatively confirmed the alterations of these three proteins following infection by western blot analysis. We also determined that the inhibition of either p38 MAPK, with the small molecule inhibitor SB 203580 or siRNA knockdown, or HSP27, by siRNA knockdown, significantly decreases JUNV replication. Our data suggests that HSP27 phosphorylation at S82 upon virus infection is dependent on p38 MAPK activity. This work sheds light on the nuances of arenavirus replication.

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.

SOCS Proteins in Immunity, Inflammatory Diseases, and Immune-Related Cancer

Cytokine signaling represents one of the cornerstones of the immune system, mediating the complex responses required to facilitate appropriate immune cell development and function that supports robust immunity. It is crucial that these signals be tightly regulated, with dysregulation underpinning immune defects, including excessive inflammation, as well as contributing to various immune-related malignancies. A specialized family of proteins called suppressors of cytokine signaling (SOCS) participate in negative feedback regulation of cytokine signaling, ensuring it is appropriately restrained. The eight SOCS proteins identified regulate cytokine and other signaling pathways in unique ways. SOCS1–3 and CISH are most closely involved in the regulation of immune-related signaling, influencing processes such polarization of lymphocytes and the activation of myeloid cells by controlling signaling downstream of essential cytokines such as IL-4, IL-6, and IFN-γ. SOCS protein perturbation disrupts these processes resulting in the development of inflammatory and autoimmune conditions as well as malignancies. As a consequence, SOCS proteins are garnering increased interest as a unique avenue to treat these disorders.

TIRAP in the Mechanism of Inflammation

The Toll-interleukin-1 Receptor (TIR) domain-containing adaptor protein (TIRAP) represents a key intracellular signalling molecule regulating diverse immune responses. Its capacity to function as an adaptor molecule has been widely investigated in relation to Toll-like Receptor (TLR)-mediated innate immune signalling. Since the discovery of TIRAP in 2001, initial studies were mainly focused on its role as an adaptor protein that couples Myeloid differentiation factor 88 (MyD88) with TLRs, to activate MyD88-dependent TLRs signalling. Subsequent studies delineated TIRAP’s role as a transducer of signalling events through its interaction with non-TLR signalling mediators. Indeed, the ability of TIRAP to interact with an array of intracellular signalling mediators suggests its central role in various immune responses. Therefore, continued studies that elucidate the molecular basis of various TIRAP-protein interactions and how they affect the signalling magnitude, should provide key information on the inflammatory disease mechanisms. This review summarizes the TIRAP recruitment to activated receptors and discusses the mechanism of interactions in relation to the signalling that precede acute and chronic inflammatory diseases. Furthermore, we highlighted the significance of TIRAP-TIR domain containing binding sites for several intracellular inflammatory signalling molecules. Collectively, we discuss the importance of the TIR domain in TIRAP as a key interface involved in protein interactions which could hence serve as a therapeutic target to dampen the extent of acute and chronic inflammatory conditions.

SOCS-1 inhibition of type I interferon restrains Staphylococcus aureus skin host defense

The skin innate immune response to methicillin-resistant Staphylococcus aureus (MRSA) culminates in the formation of an abscess to prevent bacterial spread and tissue damage. Pathogen recognition receptors (PRRs) dictate the balance between microbial control and injury. Therefore, intracellular brakes are of fundamental importance to tune the appropriate host defense while inducing resolution. The intracellular inhibitor suppressor of cytokine signaling 1 (SOCS-1), a known JAK/STAT inhibitor, prevents the expression and actions of PRR adaptors and downstream effectors. Whether SOCS-1 is a molecular component of skin host defense remains to be determined. We hypothesized that SOCS-1 decreases type I interferon production and IFNAR-mediated antimicrobial effector functions, limiting the inflammatory response during skin infection. Our data show that MRSA skin infection enhances SOCS-1 expression, and both SOCS-1 inhibitor peptide-treated and myeloid-specific SOCS-1 deficient mice display decreased lesion size, bacterial loads, and increased abscess thickness when compared to wild-type mice treated with the scrambled peptide control. SOCS-1 deletion/inhibition increases phagocytosis and bacterial killing, dependent on nitric oxide release. SOCS-1 inhibition also increases the levels of type I and type II interferon levels in vivo. IFNAR deletion and antibody blockage abolished the beneficial effects of SOCS-1 inhibition in vivo. Notably, we unveiled that hyperglycemia triggers aberrant SOCS-1 expression that correlates with decreased overall IFN signatures in the infected skin. SOCS-1 inhibition restores skin host defense in the highly susceptible hyperglycemic mice. Overall, these data demonstrate a role for SOCS-1-mediated type I interferon actions in host defense and inflammation during MRSA skin infection.

SPTBN1 inhibits inflammatory responses and hepatocarcinogenesis via the stabilization of SOCS1 and downregulation of p65 in hepatocellular carcinoma

Background: Spectrin, beta, non-erythrocytic 1 (SPTBN1), an adapter protein for transforming growth factor beta (TGF-β) signaling, is recognized as a tumor suppressor in the development of hepatocellular carcinoma (HCC); however, the underlying molecular mechanisms of this tumor suppression remain obscure.

Methods: The effects on expression of pro-inflammatory cytokines upon the inhibition or impairment of SPTBN1 in HCC cell lines and liver tissues of Sptbn1^+/- and wild-type (WT) mice were assessed by analyses of quantitative real-time reverse-transcription polymerase chain reaction (QRT-PCR), enzyme linked immunosorbent assay (ELISA), Western blotting and gene array databases from HCC patients. We investigated the detailed molecular mechanisms underlying the inflammatory responses by immunoprecipitation-Western blotting, luciferase reporter assay, chromatin immunoprecipitation quantitative real time PCR (ChIP-qPCR), immunohistochemistry (IHC) and electrophoretic mobility shift assay (EMSA). The proportion of myeloid-derived suppressor cells in liver, spleen, bone marrow and peripheral blood samples from WT and Sptbn1^+/- mice were measured by fluorescence-activated cell sorting (FACS) analysis. Further, the hepatocacinogenesis and its correlation with inflammatory microenvironment by loss of SPTBN1/SOCS1 and induction of p65 were analyzed by treating WT and Sptbn1^+/- mice with 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC).

Results: Loss of SPTBN1 in HCC cells upregulated the expression of pro-inflammatory cytokines including interleukin-1α (IL-1α), IL-1β, and IL-6, and enhanced NF-κB transcriptional activation. Mechanistic analyses revealed that knockdown of SPTBN1 by siRNA downregulated the expression of suppressor of cytokine signaling 1 (SOCS1), an E3 ligase of p65, and subsequently upregulated p65 accumulation in the nucleus of HCC cells. Restoration of SOCS1 abrogated this SPTBN1 loss-associated elevation of p65 in HCC cells. In human HCC tissues, SPTBN1 gene expression was inversely correlated with gene expression of IL-1α, IL-1β and IL-6. Furthermore, a decrease in the levels of SPTBN1 gene, as well as an increase in the gene expression of IL-1β or IL-6 predicted shorter relapse free survival in HCC patients, and that HCC patients with low expression of SPTBN1 or SOCS1 protein is associated with poor survival. Heterozygous loss of SPTBN1 (Sptbn1^+/-) in mice markedly upregulated hepatic expression of IL-1α, IL-1β and IL-6, and elevated the proportion of myeloid-derived suppressor cells (MDSCs) and CD4⁺CD25⁺Foxp3⁺ regulatory T cells (Foxp3⁺Treg) cells in the liver, promoting hepatocarcinogenesis of mouse fed by DDC.

Conclusions: Our findings provided evidence that loss of SPTBN1 in HCC cells increases p65 protein stability via the inhibition of SOCS1 and enhances NF-κB activation, stimulating the release of inflammatory cytokines, which are critical molecular mechanisms for the loss of SPTBN1-induced liver cancer formation. Reduced SPTBN1 and SOCS1 predict poor outcome in HCC patients.

Understanding, predicting and achieving liver transplant tolerance: from bench to bedside

In the past 40 years, liver transplantation has evolved from a high-risk procedure to one that offers high success rates for reversal of liver dysfunction and excellent patient and graft survival. The liver is the most tolerogenic of transplanted organs; indeed, immunosuppressive therapy can be completely withdrawn without rejection of the graft in carefully selected, stable long-term liver recipients. However, in other recipients, chronic allograft injury, late graft failure and the adverse effects of anti-rejection therapy remain important obstacles to improved success. The liver has a unique composition of parenchymal and immune cells that regulate innate and adaptive immunity and that can promote antigen-specific tolerance. Although the mechanisms underlying liver transplant tolerance are not well understood, important insights have been gained into how the local microenvironment, hepatic immune cells and specific molecular pathways can promote donor-specific tolerance. These insights provide a basis for the identification of potential clinical biomarkers that might correlate with tolerance or rejection and for the development of novel therapeutic targets. Innovative approaches aimed at promoting immunosuppressive drug minimization or withdrawal include the adoptive transfer of donor-derived or recipient-derived regulatory immune cells to promote liver transplant tolerance. In this Review, we summarize and discuss these developments and their implications for liver transplantation.

SOCS Proteins Participate in the Regulation of Innate Immune Response Caused by Viruses

The host immune system has multiple innate immune receptors that can identify, distinguish and react to viral infections. In innate immune response, the host recognizes pathogen-associated molecular patterns (PAMP) in nucleic acids or viral proteins through pathogen recognition receptors (PRRs), especially toll-like receptors (TLRs) and induces immune cells or infected cells to produce type I Interferons (IFN-I) and pro-inflammatory cytokines, thus when the virus invades the host, innate immunity is the earliest immune mechanism. Besides, cytokine-mediated cell communication is necessary for the proper regulation of immune responses. Therefore, the appropriate activation of innate immunity is necessary for the normal life activities of cells. The suppressor of the cytokine signaling proteins (SOCS) family is one of the main regulators of the innate immune response induced by microbial pathogens. They mainly participate in the negative feedback regulation of cytokine signal transduction through Janus kinase signal transducer and transcriptional activator (JAK/STAT) and other signal pathways. Taken together, this paper reviews the SOCS proteins structures and the function of each domain, as well as the latest knowledge of the role of SOCS proteins in innate immune caused by viral infections and the mechanisms by which SOCS proteins assist viruses to escape host innate immunity. Finally, we discuss potential values of these proteins in future targeted therapies.

EGF-GH Axis in Rat Steatotic and Non-steatotic Liver Transplantation From Brain-dead Donors

BACKGROUND

We evaluated the potential dysfunction caused by changes in growth hormone (GH) levels after brain death (BD), and the effects of modulating GH through exogenous epidermal growth factor (EGF) in steatotic and nonsteatotic grafts.

METHODS

Steatotic and nonsteatotic grafts from non-BD and BD rat donors were cold stored for 6 hours and transplanted to live rats. Administration of GH and EGF and their underlying mechanisms were characterized in recipients of steatotic and nonsteatotic grafts from BD donors maintained normotensive during the 6 hours before donation. Circulating and hepatic GH and EGF levels, hepatic damage, and regeneration parameters were evaluated. Recipient survival was monitored for 14 days. Somatostatin, ghrelin, and GH-releasing hormones that regulate GH secretion from the anterior pituitary were determined. The survival signaling pathway phosphoinositide-3-kinase/protein kinase B that regulates inflammation (suppressors of cytokine signaling, high-mobility group protein B1, oxidative stress, and neutrophil accumulation) was evaluated.

RESULTS

BD reduced circulating GH and increased GH levels only in steatotic livers. GH administration exacerbated adverse BD-associated effects in both types of graft. Exogenous EGF reduced GH in steatotic livers, thus activating cell proliferation and survival signaling pathways, ultimately reducing injury and inflammation. However, EGF increased GH in nonsteatotic grafts, which exacerbated damage. The benefits of EGF for steatotic grafts were associated with increased levels of somatostatin, a GH inhibitor, whereas the deleterious effect on nonsteatotic grafts was exerted through increased amounts of ghrelin, a GH stimulator.

CONCLUSIONS

GH treatment is not appropriate in rat liver transplant from BD donors, whereas EGF (throughout GH inhibition) protects only in steatotic grafts.

Transcriptome Analysis of Paralichthys olivaceus Erythrocytes Reveals Profound Immune Responses Induced by Edwardsiella tarda Infection

Unlike mammalian red blood cells (RBCs), fish RBCs are nucleated and thus capable of gene expression. Japanese flounder (Paralichthys olivaceus) is a species of marine fish with important economic values. Flounder are susceptible to Edwardsiella tarda, a severe bacterial pathogen that is able to infect and survive in flounder phagocytes. However, the infectivity of and the immune response induced by E. tarda in flounder RBCs are unclear. In the present research, we found that E. tarda was able to invade and replicate inside flounder RBCs in both in vitro and in vivo infections. To investigate the immune response induced by E. tarda in RBCs, transcriptome analysis of the spleen RBCs of flounder challenged with E. tarda was performed. Six sequencing libraries were constructed, and an average of 43 million clean reads per library were obtained, with 85% of the reads being successfully mapped to the genome of flounder. A total of 1720 differentially expressed genes (DEGs) were identified in E. tarda-infected fish. The DEGs were significantly enriched in diverse Gene Ontology (GO) terms and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, especially those associated with immunity, disease, and infection. Ninety-one key DEGs involved in 12 immune-related pathways were found to form extensive interaction networks. Twenty-one genes that constituted the hub of the networks were further identified, which were highly regulated by E. tarda and involved in a number of immune processes, notably pathogen recognition and signal transduction, antigen processing and presentation, inflammation, and splicing. These results provide new insights into the immune role of flounder RBCs during bacterial infection.

microRNA-155 Modulates Hepatic Stellate Cell Proliferation, Apoptosis, and Cell Cycle Progression in Rats With Alcoholic Hepatitis via the MAPK Signaling Pathway Through Targeting SOCS1

The aim of this study was to investigate the regulatory function of the non-coding microRNA-155 (miR-155) and suppressor of cytokine signaling 1 (SOCS1) in alcoholic hepatitis (AH) and its potential mechanism associated with the mitogen-activated protein kinase (MAPK) signaling pathway. Levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), albumin (ALB), total bilirubin (TBIL), malondialdehyde (MDA), and superoxide dismutase (SOD) were measured in a rat model of AH. The biological prediction website microRNA.org and dual-luciferase reporter gene assay were used to identify whether SOCS1 was a direct target of miR-155, and the effects of miR-155 and SOCS1 on the viability, cycle progression, and apoptosis of hepatic stellate cells were assessed using RT-qPCR, Western blot assay, MTT assay, Annexin V/PI double staining, and PI single staining. The levels of ALT, AST, MDA, and TBIL and the liver cell morphology were all prominently changed in AH model rats. miR-155 suppressed SOCS1 by specifically binding to SOCS1-3'-UTR to activate the MAPK signaling pathway. SOCS1 had low expression while miR-155 was highly expressed in AH rats. miR-155 promoted hepatic stellate cell viability and cycle progression and reduced cell apoptosis by silencing SOCS1. Together, we find that silenced miR-155 could upregulate SOCS1 and inactivate the MAPK signaling pathway, thereby inhibiting the proliferation of alcoholic hepatic stellate cells and promoting cell apoptosis.

Clinical Correlation of Blood Cells with Suppression of Cytokine Signaling Gene Expression in Hepatitis C Virus-Infected Patients

Both innate and adaptive immune responses of host are regulated by fine balance between negative and positive signals to ensure their termination and onset on entry of pathogens. Suppressor of cytokine signaling (SOCS) genes inhibit cytokine signaling pathways and regulate innate and adaptive immunity. SOCS genes perform their function by positive and negative regulation of macrophages, development and differentiation of T cells, and activation of dendritic cells. Although the role of SOCS1 and SOCS3 genes in hepatitis C virus (HCV) patients has been well studied, the correlation of SOCS1 gene expression with complete blood count in HCV-positive patients has not been established yet. We observed a weak positive correlation of SOCS1 gene expression with hemoglobin (Hb) and platelet count, whereas leukocytes were negatively correlated with the expression. This study also provides a comparative analysis of complete blood count between healthy subjects and HCV-positive subjects. The findings suggest that Hb and platelet count were significantly lower (P < 0.0001) in HCV patients than in healthy subjects.

The Association between SOCS1-1656G>A Polymorphism, Insulin Resistance and Obesity in Nonalcoholic Fatty Liver Disease (NAFLD) Patients

Suppressor of cytokine signaling (SOCS) proteins prevent uncontrolled cytokine signaling and appear to play a role in the pathological processes behind obesity and insulin resistance. The polymorphism of the SOCS1 gene (rs243330, −1656G>A) is associated with obesity and glucose sensitivity. To estimate the effect of this SOCS1 gene polymorphism on nonalcoholic fatty liver disease (NAFLD) susceptibility, we performed a study on 138 patients with ultrasound-confirmed NAFLD and 1000 healthy blood donors. The relationship between the SOCS1−1656G>A polymorphism and serum biochemical parameters in NAFLD was additionally investigated. The SOCS1 variant was genotyped using a dedicated TaqMan assay. The frequency of rs243330 polymorphism did not differ between patients and controls. However, in a cohort of obese individuals (BMI ≥ 30 kg/m²) the occurrence of the G allele of the SOCS1−1656G>A polymorphism was strongly associated with NAFLD (odds ratio (OR) 1.6; 95% CI,1.1–2.5; p = 0.009), and carriers of the AA genotype have lower risk of developing NAFLD (OR 0.4; 95% CI, 0.2–0.7; p = 0.004). Overweight NAFLD patients who were carriers of GG genotypes had significantly lower levels of homeostasis model assessment of insulin resistance (HOMA-IR) values (p = 0.03 vs. AA), and the obese GG homozygotes had lower serum concertation of triglyceride (GG vs. AA; p = 0.02). Serum liver enzyme activities were not modified by the presence of SOCS1 risk variants. In conclusion, the observed phenotype of overweight NAFLD patients with non-elevated levels of TG and HOMA-IR, which is associated with genetic variants of SOCS1, provides a rationale for further research on the pathophysiology of fatty liver disease.

microRNA-221 restricts human cytomegalovirus replication via promoting type I IFN production by targeting SOCS1/NF-κB pathway

HCMV is a common pathogen for human with relatively high prevalence, which could be life-threatened in immunodeficient patients and lead to significant birth defects in newborns. In this study, we firstly report that HCMV infection significantly enhances the expression of microRNA-221 (miR-221) in Neural Precursor Cells (NPCs). We found that miR-221 directly targets at the 3'-UTR of suppressor of cytokine signaling 1 (SOCS1) and suppresses SOCS1 expression at the both mRNA and protein levels. MiR-221 overexpression restrained HCMV replication by promoting type I interferon (IFN) and interferon stimulating genes (ISGs) production, whereas reintroduction of SOCS1 abrogated the miR-221-induced effects on HCMV replication. Importantly, miR-221 positively regulated the phosphorylation and activation of NF-κB by suppressing SOCS1. What's more, miR-221 agomir alleviated MCMV-induced tissue injury by promoting type I IFN antiviral activities in vivo. Thus, miR-221 modulates the infection and replication of HCMV as an intrinsic antiviral factor, and could be developed as a treatment target for anti-HCMV treatment.

Hepatocyte growth control by SOCS1 and SOCS3

The extraordinary capacity of the liver to regenerate following injury is dependent on coordinated and regulated actions of cytokines and growth factors. Whereas hepatocyte growth factor (HGF) and epidermal growth factor (EGF) are direct mitogens to hepatocytes, inflammatory cytokines such as TNFα and IL-6 also play essential roles in the liver regeneration process. These cytokines and growth factors activate different signaling pathways in a sequential manner to elicit hepatocyte proliferation. The kinetics and magnitude of these hepatocyte-activating stimuli are tightly regulated to ensure restoration of a functional liver mass without causing uncontrolled cell proliferation. Hepatocyte proliferation can become deregulated under conditions of chronic inflammation, leading to accumulation of genetic aberrations and eventual neoplastic transformation. Among the control mechanisms that regulate hepatocyte proliferation, negative feedback inhibition by the 'suppressor of cytokine signaling (SOCS)' family proteins SOCS1 and SOCS3 play crucial roles in attenuating cytokine and growth factor signaling. Loss of SOCS1 or SOCS3 in the mouse liver increases the rate of liver regeneration and renders hepatocytes susceptible to neoplastic transformation. The frequent epigenetic repression of the SOCS1 and SOCS3 genes in hepatocellular carcinoma has stimulated research in understanding the growth regulatory mechanisms of SOCS1 and SOCS3 in hepatocytes. Whereas SOCS3 is implicated in regulating JAK-STAT signaling induced by IL-6 and attenuating EGFR signaling, SOCS1 is crucial for the regulation of HGF signaling. These two proteins also module the functions of certain key proteins that control the cell cycle. In this review, we discuss the current understanding of the functions of SOCS1 and SOCS3 in controlling hepatocyte proliferation, and its implications to liver health and disease.

Role of SOCS1 Gene in Chronic Hepatitis C Virus Patients: A Mini-Review

Hepatitis C virus (HCV) is a global health problem, with an estimated bioburden of >180 million. Every year about 350,000 people die from HCV-associated liver complications such as cirrhosis and cancer (e.g., hepatocellular carcinoma). Pakistan has the second highest prevalence of HCV. Treatment of this life-threatening disease has been a challenge, but recent developments in direct-acting antivirals have offered hope to many. Although direct-acting antivirals have dramatically improved viral clearance, their exorbitant costs put them out of reach for patients in developing countries. Thus, interferon therapy is still being used in Pakistan. Specifically, interferon-stimulating genes can alter treatment response. For example, interferons induce expression of many antiviral genes through signal transducer and activator of transcription/Janus kinase signaling. Suppressor of cytokine signaling genes play an eminent role in the inhibition of cytokine signaling pathways and regulation of both adaptive and innate immunity. The present review examines expression of suppressor of cytokine signaling-1 in HCV-treated patients.

MicroRNA-155 promotes pro-inflammatory functions and augments apoptosis of monocytes/macrophages during Vibrio anguillarum infection in ayu, Plecoglossus altivelis

Upon recognition of pathogen-associated molecular patterns by pattern-recognition receptors, immune cells are recruited, and multiple antibacterial/viral signaling pathways are activated, leading to the production of immune-related cytokines, chemokines, and interferons along with further activation of the adaptive immune response. MicroRNAs (miRs) play essential roles in regulating such immune signaling pathways, as well as the biological activities of immune cells; however, knowledge regarding the roles of miRs in the immune-related function of monocytes/macrophages (MO/MΦ) remains limited in teleosts. In the present study, we addressed the effects of miR-155 on Vibrio anguillarum-infected MO/MΦ. Our results showed that miR-155 augmented MO/MΦ expression of proinflammatory cytokines and attenuated the expression of anti-inflammatory cytokines. Additionally, the phagocytosis and bacteria-killing abilities of these cells were boosted by miR-155 administration, which also promoted M1-type polarization but inhibited M2-type polarization. Furthermore, the V. anguillarum-infection-induced apoptosis was also enhanced by miR-155 mimic transfection, which might have been due to excessive inflammation or the accumulation of reactive oxygen species. These results represent the first report providing a detailed account of the regulatory roles of miR-155 on MO/MΦ functions in teleosts and offer insight into the evolutionary history of miR-155-mediated regulation of host immune responses.

The Expression of SOCS and NF-ϰB p65 in Hypopharyngeal Carcinoma

BACKGROUND

Hypopharyngeal carcinoma is one of the most common types of head and neck tumors. Suppressers of cytokine signalling (SOCS) family members are key regulators of cytokine homeostasis, they play important roles in the process of cell proliferation, differentiation, maturation and apoptosis, and participate in the occurrence and development of tumor. The abnormal activation of NF-ϰB is an important feature of the tumor. The aim of this study was to investigate the relationships among SOCS, NF-ϰB p65 and hypopharyngeal carcinoma development.C.

METHODS

We included 72 hypopharyngeal cancer patients and 9 swallow cyst patients. The patients were recruited at The Second Hospital of Shandong University (Jinan, China) between 2014 and 2016. The mRNA and protein expression levels of SOCS-1, SOCS-3 and NF-ϰB p65 in hypopharyngeal carcinoma tissues, para-cancerous tissues and control tissues were detected by RT-PCR and Western blot analysis, respectively.

RESULTS

Hypopharyngeal carcinoma tissues had lower level expression of SOCS-1 and SOCS-3 than pericarcinoma tissues, but there was no significant difference, while cancer tissues had significantly higher level expression of NF-ϰB p65 than that of pericarcinoma tissues (0.412±0.266, 0.281±0.231, t=2.969, P=0.004). The early stage patients had striking higher level expression of SOCS-1 and SOCS-3 than that in advanced stages (F=16.202, P<0.001; F=52.295, P<0.001), while the expression of NF-ϰB p65 in early stages had lower level than that in advanced stages (F=3.383, P=0.04).

CONCLUSION

SOCS-1, SOCS-3 may be protective factors while NF-ϰB p65 could be a harmful factor in hypopharyngeal carcinoma.

Increased Expression of Resistin in MicroRNA-155-Deficient White Adipose Tissues May Be a Possible Driver of Metabolically Healthy Obesity Transition to Classical Obesity

We reported that microRNA-155 (miR-155) deficiency in ApoE-/- mice yields a novel metabolically healthy obese (MHO) model, which exhibits improved atherosclerosis but results in obesity, non-alcoholic fatty liver disease (NAFLD) without insulin resistance. Using experimental data mining approaches combined with experiments, we found that, among 109 miRNAs, miR-155, and miR-221 are significantly modulated in all four hyperlipidemia-related diseases (HRDs), namely atherosclerosis, NAFLD, obesity and type II diabetes (T2DM). MiR-155 is significantly upregulated in atherosclerosis and decreased in other HRDs. MiR-221 is increased in three HRDs but reduced in obesity. These findings led to our new classification of types I and II MHOs, which are regulated by miR-221 and miR-155, respectively. Western blots showed that the proinflammatory adipokine, resistin, is significantly increased in white adipose tissues (WAT) of the MHO mice, revealing our newly proposed, miR-155-suppressed “secondary wave inflammatory state (SWIS),” characteristic of MHO transition to classical obesity (CO). Taken together, we are first to show that MHO may have heterogeneity in comorbidities, and is therefore classified into type I, and type II MHOs; and that increased expression of resistin in miR-155-/- white adipose tissues may be a driver for SWIS in MHO transition to CO. Our findings provide novel insights into the pathogenesis of MHO, MHO transition to CO, hyperlipidemic pathways related to cancer, and new therapeutic targets.

Glycine Relieves Intestinal Injury by Maintaining mTOR Signaling and Suppressing AMPK, TLR4, and NOD Signaling in Weaned Piglets after Lipopolysaccharide Challenge

This study was conducted to envaluate whether glycine could alleviate Escherichia coli lipopolysaccharide (LPS)-induced intestinal injury by regulating intestinal epithelial energy status, protein synthesis, and inflammatory response via AMPK, mTOR, TLR4, and NOD signaling pathways. A total of 24 weanling piglets were randomly allotted to 1 of 4 treatments: (1) non-challenged control; (2) LPS-challenged control; (3) LPS + 1% glycine; (4) LPS + 2% glycine. After 28 days feeding, piglets were injected intraperitoneally with saline or LPS. The pigs were slaughtered and intestinal samples were collected at 4 h postinjection. The mRNA expression of key genes in these signaling pathways was measured by real-time PCR. The protein abundance was measured by Western blot analysis. Supplementation with glycine increased jejunal villus height/crypt depth ratio. Glycine also increased the jejunal and ileal protein content, RNA/DNA ratio, and jejunal protein/DNA ratio. The activities of citroyl synthetase in ileum, and α-ketoglutarate dehydrogenase complex in jejunum, were increased in the piglets fed diets supplemented with glycine. In addition, glycine decreased the jejunal and ileal phosphorylation of AMPKα, and increased ileal phosphorylation of mTOR. Furthermore, glycine downregulated the mRNA expression of key genes in inflammatory signaling. Meanwhile, glycine increased the mRNA expression of negative regulators of inflammatory signaling. These results indicate that glycine supplementation could improve energy status and protein synthesis by regulating AMPK and mTOR signaling pathways, and relieve inflammation by inhibiting of TLR4 and NOD signaling pathways to alleviate intestinal injury in LPS-challenged piglets.

MiRNA-155 Regulates the Th17/Treg Ratio by Targeting SOCS1 in Severe Acute Pancreatitis

Acute pancreatitis (AP) is a serious condition associated with intestinal barrier disruption or inflammation of the pancreatic tissue. Specific microRNAs are involved in the pathogenesis of AP, during which IL-17-producing CD4⁺ T helper (Th17) cells accumulate in the pancreas. In this study, significantly increased levels of miR-155 were detected in clinical samples from patients with AP, and overexpression of miR-155 correlated with severe AP (SAP). To identify the effect of miR-155 on T cell differentiation, we isolated CD4⁺ T lymphocytes and in vitro experiments showed that inhibition of miR-155 significantly reversed the stress-induced increase in the Th17/Treg ratio. The results also showed that miR-155 increased the Th17-mediated inflammatory response by targeting SOCS1. The interaction between miR-155 and the 3^′-UTR of SOCS1 was confirmed by a dual luciferase reporter assay and RT-PCR. Experimental AP of varying severity was induced in BALB/c mice by caerulein hyperstimulation and miR-155 expression was found to increase with disease progression. Inhibition of miR-155 expression significantly improved the pathology of the pancreas. We also observed downregulation of expression of inflammatory factors, IL-17, SOCS1 and phosphorylated STAT1 after miR-155 inhibition. In summary, miR-155 regulates the Th17/Treg ratio by targeting SOCS1, most probably via direct binding to its 3^′-UTR region, indicating that this microRNA may be a potential biomarker and/or therapeutic target for AP.

gga-miR-155 Enhances Type I Interferon Expression and Suppresses Infectious Burse Disease Virus Replication via Targeting SOCS1 and TANK

Infectious bursal disease (IBD) is an acute, highly contagious, and immunosuppressive avian disease caused by IBD virus (IBDV). MicroRNAs (miRNAs) are involved in host-pathogen interactions and innate immune response to viral infection. However, the role of miRNAs in host response to IBDV infection is not clear. We report here that gga-miR-155 acts as an anti-virus host factor inhibiting IBDV replication. We found that transfection of DF-1 cells with gga-miR-155 suppressed IBDV replication, while blockage of the endogenous gga-miR-155 by inhibitors enhanced IBDV replication. Furthermore, our data showed that gga-miR-155 enhanced the expression of type I interferon in DF-1 cells post IBDV infection. Importantly, we found that gga-miR-155 enhanced type I interferon expression via targeting SOCS1 and TANK, two negative regulators of type I IFN signaling. These results indicate that gga-miR-155 plays a critical role in cell response to IBDV infection.

The role of lnc-DC long non-coding RNA and SOCS1 in the regulation of STAT3 in coronary artery disease and type 2 diabetes mellitus

AIMS

Coronary artery disease (CAD) can be classified as an inflammatory disease, which affected by type 2 diabetes mellitus (T2DM). Elevated levels of many inflammatory molecules were found in the serum of patients with CAD. STAT3 molecule as a transcription factor plays an important role in the cytokines expression. Here, we examined the expression levels of STAT3 and its important regulatory genes lnc-DC and SOCS1, in patients with CAD and T2DM.

METHODS

Blood samples were obtained from 37 CAD+ and 36 CAD- patients. These patients were enrolled in this study based on angiography findings and categorized based on T2DM status. The expression levels of STAT3, lnc-DC and SOCS1 genes were examined with Real time PCR method.

RESULTS

A significant increase was observed in expression of STAT3 and lnc-DC genes but not SOCS1 in CAD+ versus CAD- patients. These results replicated partially in some groups categorized based on T2DM and CAD status. However, severity of CAD had no effect on expressions of these genes. Moreover, we found some significant correlations between expressions of lnc-DC with SOCS1 and STAT3, which confirmed by in silico analysis.

CONCLUSION

Our results shed further light to the inflammatory aspects of CAD and T2DM with emphasis to JAK/STAT pathway and the regulatory role of long non-coding RNAs in the physiopathology of these diseases.

Constitutively elevated levels of SOCS1 suppress innate responses in DF-1 immortalised chicken fibroblast cells

The spontaneously immortalised DF-1 cell line is rapidly replacing its progenitor primary chicken embryo fibroblasts (CEFs) for studies on avian viruses such as avian influenza but no comprehensive study has as yet been reported comparing their innate immunity phenotypes. We conducted microarray analyses of DF-1 and CEFs, under both normal and stimulated conditions using chicken interferon-α (chIFN-α) and the attenuated infectious bursal disease virus vaccine strain PBG98. We found that DF-1 have an attenuated innate response compared to CEFs. Basal expression levels of Suppressor of Cytokine Signalling 1 (chSOCS1), a negative regulator of cytokine signalling in mammals, are 16-fold higher in DF-1 than in CEFs. The chSOCS1 “SOCS box” domain (which in mammals, interacts with an E3 ubiquitin ligase complex) is not essential for the inhibition of cytokine-induced JAK/STAT signalling activation in DF-1. Overexpression of SOCS1 in chIFN-α-stimulated DF-1 led to a relative decrease in expression of interferon-stimulated genes (ISGs; MX1 and IFIT5) and increased viral yield in response to PBG98 infection. Conversely, knockdown of SOCS1 enhanced induction of ISGs and reduced viral yield in chIFN-α-stimulated DF-1. Consequently, SOCS1 reduces induction of the IFN signalling pathway in chicken cells and can potentiate virus replication.

SOCS Proteins as Regulators of Inflammatory Responses Induced by Bacterial Infections: A Review

Severe bacterial infections can lead to both acute and chronic inflammatory conditions. Innate immunity is the first defense mechanism employed against invading bacterial pathogens through the recognition of conserved molecular patterns on bacteria by pattern recognition receptors (PRRs), especially the toll-like receptors (TLRs). TLRs recognize distinct pathogen-associated molecular patterns (PAMPs) that play a critical role in innate immune responses by inducing the expression of several inflammatory genes. Thus, activation of immune cells is regulated by cytokines that use the Janus kinase/signal transducers and activators of transcription (JAK/STAT) signaling pathway and microbial recognition by TLRs. This system is tightly controlled by various endogenous molecules to allow for an appropriately regulated and safe host immune response to infections. Suppressor of cytokine signaling (SOCS) family of proteins is one of the central regulators of microbial pathogen-induced signaling of cytokines, principally through the inhibition of the activation of JAK/STAT signaling cascades. This review provides recent knowledge regarding the role of SOCS proteins during bacterial infections, with an emphasis on the mechanisms involved in their induction and regulation of antibacterial immune responses. Furthermore, the implication of SOCS proteins in diverse processes of bacteria to escape host defenses and in the outcome of bacterial infections are discussed, as well as the possibilities offered by these proteins for future targeted antimicrobial therapies.

Antimicrobial Peptide Epinecidin-1 Modulates MyD88 Protein Levels via the Proteasome Degradation Pathway

The cationic antimicrobial peptide epinecidin-1 was identified from Epinephelus coioides and possesses multiple biological functions, including antibacterial, antifungal, anti-tumor, and immunomodulatory effects. In addition, epinecidin-1 suppresses lipopolysaccharide (LPS)-induced inflammation by neutralizing LPS and ameliorating LPS/Toll-like receptor (TLR)-4 internalization. However, it is unclear whether the actions of epinecidin-1 depend on the regulation of TLR adaptor protein MyD88 or endogenous TLR signaling antagonists, which include A20, interleukin-1 receptor associated kinase (IRAK)-M, and suppressor of cytokine signaling (SOCS)-1. Our results demonstrate that epinecidin-1 alone does not affect A20, IRAK-M, or SOCS-1 protein levels. However, pre-incubation of epinecidin-1 significantly inhibits LPS-induced upregulation of A20, IRAK-M, and SOCS-1. In addition, epinecidin-1 significantly reduces the abundance of MyD88 protein. Both MG132 (a specific proteasome inhibitor) and Heclin (a specific Smurf E3 ligase inhibitor) are able to abolish epinecidin-1-mediated MyD88 degradation. Thus, our data suggest that epinecidin-1 directly inhibits MyD88 via induction of the Smurf E3 ligase proteasome pathway.

SOCS1 and pattern recognition receptors: TLR9 and RIG-I; novel haplotype associations in Egyptian fibrotic/cirrhotic patients with HCV genotype 4

In this paper we explore the role of suppressor of cytokine signaling 1 (SOCS1) (rs243327), the regulator of toll-like receptor-9 (TLR9) (rs352140), retinoic acid inducible gene-I (RIG-I) (rs669260), and cluster of differentiation 152 (CD152) (rs231776) in fibrotic/cirrhotic patients. Single nucleotide polymorphisms (SNPs) within these genes as well as haplotype analyses were performed on a cohort of 120 Egyptian fibrotic patients. Fibrosis had progressed from HCV genotype 4 infections. Using RT-PCR, SNPs were evaluated in the DNA collected from each patient using TaqMan® genotyping assays. A regression model was used to evaluate allelic and haplotypic associations with a fibrosis/cirrhotic scale. The necroinflammatory A score was adjusted for non-genetic covariates. The genotype distributions for SOCS1 (rs243327) and TLR-9 (rs352140) differed significantly between the F1-F3 and F3-F4 groups. On the other hand, the genotype distributions for RIG-I (rs669260) and CD152 (rs231776) genes did not significantly differ. The allele frequency was calculated using Hardy-Weinberg Equilibrium (HWE) for the SOCS1 (rs243327), RIG-I (rs669260), and CD152 (rs231776) genes. These calculated frequency values indicated the need to compare them to another population for that locus. However, TLR9 (rs352140) did not show similar results. The A allele in SOCS1, TLR9, and RIG-I SNPs was an adverse prognostic factor for liver fibrosis and liver activity. Haplotype analysis revealed a significant association between SOCS1 and TLR9 in fibrotic/cirrhotic patients. This indicated the presence of the A allele in either gene, which is considered a risk factor for the progression of liver disease to cirrhosis. SOCS1 rs243327, TLR9 rs352140, and RIG-I rs669260 polymorphisms might affect liver pathophysiology and the cirrhotic outcome following genotype 4 HCV infection. Therefore, performing this specific SNP testing may be of value for the stratification of the population at risk.

Suppressor of cytokine signaling 1 expression during LPS-induced inflammation and bone loss in rats

This study aimed to characterize the dynamics of suppressor of cytokine signaling (SOCS1) expression in a rat model of lipopolysaccharide-induced periodontitis. Wistar rats in the experimental groups were injected three times/week with LPS from Escherichia coli on the palatal aspect of the first molars, and control animals were injected with vehicle (phosphate-buffered saline). Animals were sacrificed 7, 15, and 30 days after the first injection to analyze inflammation (stereometric analysis), bone loss (macroscopic analysis), gene expression (qRT-PCR), and protein expression/activation (Western blotting). The severity of inflammation and bone loss associated with LPS-induced periodontitis increased from day 7 to day 15, and it was sustained through day 30. Significant (p < 0.05) increases in SOCS1, RANKL, OPG, and IFN-γ gene expression were observed in the experimental group versus the control group at day 15. SOCS1 protein expression and STAT1 and NF-κB activation were increased throughout the 30-day experimental period. Gingival tissues affected by experimental periodontitis express SOCS1, indicating that this protein may potentially downregulate signaling events involved in inflammatory reactions and bone loss and thus may play a relevant role in the development and progression of periodontal disease.

SOCS1 is a negative regulator of metabolic reprogramming during sepsis

Sepsis can induce an overwhelming systemic inflammatory response, resulting in organ damage and death. Suppressor of cytokine signaling 1 (SOCS1) negatively regulates signaling by cytokine receptors and Toll-like receptors (TLRs). However, the cellular targets and molecular mechanisms for SOCS1 activity during polymicrobial sepsis are unknown. To address this, we utilized a cecal ligation and puncture (CLP) model for sepsis; C57BL/6 mice subjected to CLP were then treated with a peptide (iKIR) that binds the SOCS1 kinase inhibitory region (KIR) and blocks its activity. Treatment with iKIR increased CLP-induced mortality, bacterial burden, and inflammatory cytokine production. Myeloid cell-specific SOCS1 deletion (Socs1Δmyel) mice were also more susceptible to sepsis, demonstrating increased mortality, higher bacterial loads, and elevated inflammatory cytokines, compared with Socs1fl littermate controls. These effects were accompanied by macrophage metabolic reprograming, as evidenced by increased lactic acid production and elevated expression of the glycolytic enzymes hexokinase, lactate dehydrogenase A, and glucose transporter 1 in septic Socs1Δmyel mice. Upregulation was dependent on the STAT3/HIF-1α/glycolysis axis, and blocking glycolysis ameliorated increased susceptibility to sepsis in iKIR-treated CLP mice. These results reveal a role of SOCS1 as a regulator of metabolic reprograming that prevents overwhelming inflammatory response and organ damage during sepsis.

Goat whey ameliorates intestinal inflammation on acetic acid-induced colitis in rats

Complementary or alternative medicine is of great interest for the treatment of inflammatory bowel disease, with the aim of ameliorating the side effects of the drugs commonly used or improving their efficacy. In this study, we evaluated the ability of goat whey to prevent intestinal inflammation in the experimental model of acetic acid-induced rats and compared it to sulfasalazine. Pretreatment with goat whey (1, 2, and 4g/kg) and sulfasalazine (250mg/kg) on colitic rats improved colonic inflammatory markers, including myeloperoxidase activity, leukotriene B₄ levels, as well as the production of proinflammatory cytokines IL-1β and tumor necrosis factor-α. Furthermore, the administration of goat whey significantly reduced the colonic oxidative stress by reducing malondialdehyde levels and increased total glutathione content, a potent antioxidant peptide. The histological evaluation of the colonic specimens from colitic rats confirmed these beneficial effects, as goat whey preserved the colonic tissue, especially in those rats treated with the highest dose of goat whey or with sulfasalazine. The immunohistochemistry analysis of the colonic tissue evaluation also revealed a reduction in the expression of cyclooxygenase-2, inducible nitric oxide synthase, and matrix metalloproteinase-9, together with an increased expression of suppressor of cytokine signaling-1. These results suggest that goat whey exerted a preventive effect against the intestinal damage induced by acetic acid, showing a similar efficacy to that shown by sulfasalazine, therefore making it a potential treatment for human inflammatory bowel disease.

Mincle suppresses Toll-like receptor 4 activation

Regulation of Toll-like receptor responses is critical for limiting tissue injury and autoimmunity in both sepsis and sterile inflammation. We found that Mincle, a C-type lectin receptor, regulates proinflammatory Toll-like receptor 4 signaling. Specifically, Mincle ligation diminishes Toll-like receptor 4-mediated inflammation, whereas Mincle deletion or knockdown results in marked hyperresponsiveness to lipopolysaccharide in vitro, as well as overwhelming lipopolysaccharide-mediated inflammation in vivo. Mechanistically, Mincle deletion does not up-regulate Toll-like receptor 4 expression or reduce interleukin 10 production after Toll-like receptor 4 ligation; however, Mincle deletion decreases production of the p38 mitogen-activated protein kinase-dependent inhibitory intermediate suppressor of cytokine signaling 1, A20, and ABIN3 and increases expression of the Toll-like receptor 4 coreceptor CD14. Blockade of CD14 mitigates the increased sensitivity of Mincle(-/-) leukocytes to Toll-like receptor 4 ligation. Collectively, we describe a major role for Mincle in suppressing Toll-like receptor 4 responses and implicate its importance in nonmycobacterial models of inflammation.

The MYC/miR-17-92 axis in lymphoproliferative disorders: A common pathway with therapeutic potential

MicroRNAs (miRNAs) represent a class of small non-coding single-stranded RNA molecules acting as master regulators of gene expression post transcriptionally by inhibiting the translation or inducing the degradation of target messenger RNAs (mRNAs). In particular, the miR-17-92 cluster is widely expressed in many different cell types and is essential for many developmental and pathogenic processes. As a strong oncogene, miR-17-92 can regulate multiple cellular processes that favor malignant transformation, promoting cell survival, rapid cell proliferation, and increased angiogenesis. The miR-17-92 cluster has been reported to be involved in hematopoietic malignancies including diffuse large B-cell lymphoma, mantle cell lymphoma, Burkitt's lymphoma, and chronic lymphocytic leukemia. Given the multiple and potent effects on cellular proliferation and apoptosis exerted by the miR-17-92 cluster, miRNAs belonging to the cluster surely represent attractive targets for cancer therapy also in the context of lymphoproliferative disorders. In the present review, we focus on the role of the miR-17-92 cluster in lymphoproliferative disorders, including diagnostic/prognostic implications, and on the potential applications of anti-miRNAs based therapies targeting miRNAs belonging to the cluster.

Tim-3 suppression combined with TLR3 activation enhances antiviral immune response in patients with chronic HCV infection

OBJECTIVE

To investigate the regulation mechanism of T cell immunoglobulin and mucin domain-3 (Tim-3) combined with toll-like receptor 3 (TLR3) or TLR4 on antiviral immune and inflammatory response in patients with chronic hepatitis C virus (HCV) infection.

METHODS

Patients with chronic HCV infection and healthy control subjects were recruited. Patients received interferon (IFN)-α based therapy. Plasma galectin-9 (Gal-9) was quantitated. Peripheral blood mononuclear cells (PBMCs) were cultured with TLR3 or TLR4 agonists, alone or in combination with Tim-3 antagonist. Levels of IFN-α, TNF-α, and 2'-5' oligoadenylate synthetase (2'-5'OAS), myxovirus resistance protein A (MxA) and suppressor of cytokine 1 (SOCS1) RNA in PBMC cultures were evaluated.

RESULTS

Plasma Gal-9 levels were increased in patients (n = 52) compared with controls (n = 20) and significantly declined at treatment week 12 and 24 weeks post-treatment. IFN-α, 2'-5'OAS, MxA, TNF-α and SOCS1 were upregulated by TLR3 and TLR4 agonists. TNF-α and SOCS1 levels were suppressed by the addition of Tim-3 antagonist.

CONCLUSIONS

Tim-3 blockade in combination with TLR activation induces the expression of antiviral molecules without a significant increase in TNF-α or SOCS1.