Histone methyltransferase KMT2D inhibits ENKTL carcinogenesis by epigenetically activating SGK1 and SOCS1

BACKGROUND

Epigenetic alteration plays an essential role in the occurrence and development of extranodal natural killer/T cell lymphoma (ENKTL). Histone methyltransferase (HMT) KMT2D is an epigenetic regulator that plays different roles in different tumors, but its role and mechanism in ENKTL are still unclear.

METHODS

We performed immunohistochemical staining of 112 ENKTL formalin-fixed paraffin-embedded (FFPE) samples. Then, we constructed KMT2D knockdown cell lines and conducted research on cell biological behavior. Finally, to further investigate KMT2D-mediated downstream genes, ChIP-seq and ChIP -qPCR was performed.

RESULTS

The low expression of KMT2D was related to a decreased abundance in histone H3 lysine 4 mono- and trimethylation (H3K4me1/3). In KMT2D knockdown YT and NK-YS cells, cell proliferation was faster (P < 0.05), apoptosis was decreased (P < 0.05), the abundance of S phase cells was increased (P < 0.05), and the level of H3K4me1 was decreased. Notably, ChIP-seq revealed two crucial genes and pathways downregulated by KMT2D.

CONCLUSIONS

KMT2D is a tumor suppressor gene that mediates H3K4me1 and influences ENKTL proliferation and apoptosis by regulating the cell cycle. Moreover, in ENKTL, serum- and glucocorticoid-inducible kinase-1 (SGK1) and suppressor of cytokine signaling-1 (SOCS1) are downstream genes of KMT2D.

The potential role of human HIV-1 TAT-Interactive Protein 2 levels in the pathogenesis of contact dermatitis

Background/aim

Human HIV-1 TAT interactive protein 2 (HTATIP2/TIP30) is a gene that is extensively expressed in human tissues as well as in tumor tissues. This study aimed to explore the potential role of HTATIP2/TIP30 in contact dermatitis (CD), which is one of the most common inflammatory cutaneous conditions.

Materials and methods

This cross-sectional study involved adult patients with acute contact dermatitis who were admitted to the outpatient dermatology clinic of a tertiary hospital and healthy adult volunteers without any cutaneous or systemic diseases. The blood concentration of HTATIP2/TIP30 was measured using ELISA kits.

Results

The research sample consisted of 31 patients with CD (18 males, 13 females) and 20 healthy control subjects (14 males, 6 females). The mean ages of the patients with CD and healthy volunteers were 37 and 30 years, respectively (p > 0.05). The mean value of serum HTATIP2/TIP30 levels in patients with CD was 1.65 ng ml–1, which is 0.60 ng ml–1 in the control group (p = 0.02)

Conclusion

In this study, serum levels of HTATIP2/TIP30 were statistically significantly higher in patients with CD when compared to healthy controls. This outcome may indicate possible role of HTATIP2/TIP30 in the pathogenesis of CD.

Tumor evolution selectively inactivates the core microRNA machinery for immune evasion

Cancer cells acquire genetic heterogeneity to escape from immune surveillance during tumor evolution, but a systematic approach to distinguish driver from passenger mutations is lacking. Here we investigate the impact of different immune pressure on tumor clonal dynamics and immune evasion mechanism, by combining massive parallel sequencing of immune edited tumors and CRISPR library screens in syngeneic mouse tumor model and co-culture system. We find that the core microRNA (miRNA) biogenesis and targeting machinery maintains the sensitivity of cancer cells to PD-1-independent T cell-mediated cytotoxicity. Genetic inactivation of the machinery or re-introduction of ANKRD52 frequent patient mutations dampens the JAK-STAT-interferon-γ signaling and antigen presentation in cancer cells, largely by abolishing miR-155-targeted silencing of suppressor of cytokine signaling 1 (SOCS1). Expression of each miRNA machinery component strongly correlates with intratumoral T cell infiltration in nearly all human cancer types. Our data indicate that the evolutionarily conserved miRNA pathway can be exploited by cancer cells to escape from T cell-mediated elimination and immunotherapy.

Suppressors of cytokine signaling (SOCS) proteins in inflammatory bone disorders

Suppressor of cytokine signaling (SOCS) proteins are significant regulators of cellular immune responses. Therefore, the role of SOCS in bone-inflammatory disorders, including arthritis and periodontitis, has been investigated in experimental and clinical conditions. Recent evidence shows that SOCS proteins are expressed in major bone-related cells, including osteoblasts, osteoclasts, chondrocytes and synoviocytes, although their direct role in these cells is not fully described. These signaling molecules, especially SOCS1, 2 and 3, were shown to play critical roles in the control of bone resorption associated to inflammation. This review focuses on the involvement of SOCS proteins in inflammatory bone remodeling, including their direct and indirect role in the control of osteoclast hyperactivation, during arthritis and periodontitis. The description of the roles of SOCS proteins in inflammatory bone diseases highlights the pathways involved in the pathophysiology of these conditions and, thus, may contribute to the development and improvement of potential therapeutic interventions.

Inhibiting Sphingosine Kinase 2 Derived-sphingosine-1-phosphate Ameliorates Psoriasis-like Skin Disease via Blocking Th17 Differentiation of Naïve CD4 T Lymphocytes in Mice

Sphingosine-1-phosphate (S1P) is a signalling sphingolipid metabolite that regulates important cell processes, including cell proliferation and apoptosis. Circulating S1P levels have been reported to be increased in patients with psoriasis relative to healthy patients. The aim of this study was to examine the potency of S1P inhibition using an imiquimod-induced psoriasis mouse model. Both topical ceramidase and sphingosine kinase 1/2 inhibition, which blocks S1P generation, alleviated imiquimod-induced skin lesions and reduced the serum interleukin 17-A levels induced by application of imiquimod. These treatments also normalized skin mRNA levels of genes associated with inflammation and keratinocyte differentiation. Inhibition of sphingosine kinase 2, but not sphingosine kinase 1, diminished levels of suppressor of cytokine signalling 1 and blocked T helper type 17 differentiation of naïve CD4+ T cells; imiquimod-induced psoriasis-like skin symptoms were also ameliorated. These results indicate the distinct effects of sphingosine kinase 1 and sphingosine kinase 2 inhibition on T helper type 17 generation and suggest molecules that inhibit S1P formation, including ceramidase and sphingosine kinase 2 inhibitors, as novel therapeutic candidates for psoriasis.

Resveratrol inhibits STAT3 signaling pathway through the induction of SOCS-1: Role in apoptosis induction and radiosensitization in head and neck tumor cells

BACKGROUND

Signal transducer and activator of transcription 3 (STAT3) is persistently activated in squamous cell carcinoma of the head and neck (SCCHN) and can cause uncontrolled cellular proliferation and division.

HYPOTHESIS

Thus, its targeted abrogation could be an effective strategy to reduce the risk of SCCHN. Resveratrol is known for its anti-cancer efficacy in a variety of cancer models.

STUDY DESIGN

The effect resveratrol on STAT3 activation, associated protein kinases, phosphatases, cellular proliferation and apoptosis was investigated.

METHODS

We evaluated the effect of resveratrol on STAT3 signaling cascade and its regulated functional responses in SCCHN cells.

RESULTS

We found that HN3 and FaDu cells expressed strongly phosphorylated STAT3 on both tyrosine 705 and serine 727 residues as compared to other SCCHN cells. The phosphorylation was completely suppressed by resveratrol in FaDu cells, but not substantially in HN3 cells. STAT3 suppression was mediated through the inhibition of activation of upstream JAK2, but not of JAK1 and Src kinases. Treatment with the protein tyrosine phosphatase (PTP) inhibitor pervanadate reversed the resveratrol-induced down-regulation of STAT3, thereby indicating a critical role for a PTP. We also found that resveratrol induced the expression of the SOCS-1 protein and mRNA. Further, deletion of SOCS-1 gene by siRNA suppressed the induction of SOCS-1, and reversed the inhibition of STAT3 activation. Resveratrol down-regulated various STAT3-regulated gene products, inhibited proliferation, invasion, as well as induced the cell accumulation in the sub-G1 phase and caused apoptosis. Beside, this phytoalexin also exhibited the enhancement of apoptosis when combined with ionizing radiation treatment.

CONCLUSION

Our results suggest that resveratrol blocks STAT3 signaling pathway through induction of SOCS-1, thus attenuating STAT3 phosphorylation and proliferation in SCCHN cells.

Exposure to TiO2 Nanoparticles Induces Immunological Dysfunction in Mouse Testitis

Although TiO2 nanoparticles (NPs) as endocrine disruptors have been demonstrated to be able to cross the blood-testis barriers and induce reproductive toxicity in male animals, whether the reproductive toxicity of male animals due to exposure to endocrine disruptor TiO2 NPs is related to immunological dysfunction in the testis remains not well understood. This study determined whether the reproductive toxicity and immunological dysfunction induced by exposure to TiO2 NPs is associated with activation or inhibition of TAM/TLR-mediated signal pathway in mouse testis. The results showed that male mice exhibited significant reduction of fertility, infiltration of inflammatory cells, rarefaction, apoptosis, and/or necrosis of spermatogenic cells and Sertoli cells due to TiO2 NPs. Furthermore, these were associated with decreased expression of Tyro3 (-18.16 to -66.6%), Axl (-14.7 to -57.99%), Mer (-7.98 to -72.62%), and IκB (-11.25 to -63.16%), suppression of cytokine signaling (SOCS) 1 (-21.99 to -73.8%) and SOCS3 (-8.11 to -34.86%), and increased expression of Toll-like receptor (TLR)-3 (21.4-156.03%), TLR-4 (37.0-109.87%), nuclear factor-κB (14.75-69.34%), interleukin (IL)-lβ (46.15-123.08%), IL-6 (2.54-81.98%), tumor necrosis factor-α (6.95-88.39%), interferon (IFN)-α (2.54-37.25%), and IFN-β (10.19-80.56%), which are involved in the immune environment in the testis. The findings showed that reproductive toxicity of male mice induced by exposure to endocrine disruptor TiO2 NPs may be associated with biomarkers of impairment of immune environment or dysfunction of TAM/TLR3-mediated signal pathway in mouse testitis. Therefore, the potential risks to reproductive health should be attended, especially in those who are occupationally exposed to TiO2 NPs.

Aberrant promoter methylation of SOCS-1 gene may contribute to the pathogenesis of hepatocellular carcinoma: a meta-analysis

PURPOSE

We conducted this meta-analysis of published case-control studies aiming to evaluate the relationship between abnormal suppression of cytokine signaling-1 (SOCS-1) promoter methylation and the risk of hepatocellular carcinoma (HCC).

METHODS

Relevant studies were retrieved from PubMed, Embase, Web of Science, Cochrane Library, Chinese National Knowledge Infrastructure (CNKI) and China Biological Medicine (CBM) databases without language restrictions. Meta-analysis was conducted using the STATA 12.0 software. We calculated odds ratio (OR) and its 95 % confidence interval (95% CI) to estimate the correlations.

RESULTS

Sixteen case-control studies with a total of 941 HCC patients and 114 individuals with benign liver diseases met our inclusion criteria. Our results demonstrated that the frequency of SOCS-1 promoter methylation in cancer tissues was significantly higher than in adjacent non-tumorous tissues and benign tissues (cancer tissue vs adjacent tissue: OR=3.05, 95%CI 1.62-5.77, p=0.001; cancer tissue vs benign tissue: OR=11.55, 95%CI 5.93-22.49, p=0.000). Subgroup analyses by ethnicity, detecting method and sample size also suggested that abnormal SOCS-1 promoter methylation was correlated to the risk of HCC in the majority of these subgroups.

CONCLUSION

Our findings provide empirical evidence that abnormal SOCS-1 promoter methylation may contribute to the pathogenesis of HCC. Thus, detection of SOCS-1 promoter methylation may be a valuable diagnostic biomarker for HCC.

Suppressors of cytokine signalling in ankylosing spondylitis and their associations with disease severity, acute-phase reactants and serum cytokines

OBJECTIVES

To investigate the suppressors of cytokine signalling (SOCS1 and SOCS3) expression in peripheral blood cells in ankylosing spondylitis (AS), and their associations with clinical and laboratory manifestations.

METHODS

The levels of SOCS1 and SOCS3 mRNA in peripheral blood mononuclear cells (PBMCs), T cells and monocytes were measured by RT-PCR in 53 AS patients and 31 healthy controls. Patient's serum IL-6, IL-10 and IL-17A levels were determined by ELISA. We evaluated patient's disease activity, functional ability and global assessment, and tested their ESR, CRP and IgA levels.

RESULTS

Cellular SOCS1 expression did not show significant differences between AS patients and controls. However, T cells SOCS1 decreased significantly in the AS subgroup with lower ESR than controls (p=0.013). PBMCs (p=0.047) and T cells (p=0.035) SOCS1 decreased significantly in the AS subgroup with lower CRP than controls. Importantly, SOCS3 expression increased significantly in AS patients compared to the controls in PBMCs (p=0.025), T cells (p=0.003) and monocytes (p=0.009). Moreover, PBMCs SOCS3 correlated with ESR (r=0.297, p=0.031) and CRP (r=0.320, p=0.019). T cells SOCS3 correlated with BASFI (r=0.337, p=0.015), ESR (r=0.435, p=0.001) and CRP (r=0.300, p=0.029). Monocytes SOCS3 correlated with ESR (r=0.281, p=0.041) and IgA (r=0.426, p=0.006). Furthermore, T cells SOCS1 (r=-0.454, p=0.023) and T cells SOCS3 (r=-0.405, p=0.045) negatively correlated with serum IL-17A. Monocytes SOCS3 negatively correlated with serum IL-6 (r=-0.584, p=0.002).

CONCLUSIONS

The decreased SOCS1 and increased SOCS3 expression in AS PBMCs and T cells, and their correlation with patient's functional ability, acute-phase reactants and serum pro-inflammatory cytokines suggested that SOCS may participate in the pathogenesis of AS.

Hepatitis B virus X protein upregulates DNA methyltransferase 3A/3B and enhances SOCS-1CpG island methylation

The aim of the present study was to investigate the effect of hepatitis B virus X protein (HBx) on the expression of DNA methyltransferase (DNMT)3A/3B and suppressors of cytokine signaling‑1 (SOCS‑1), as well as promoter CpG island methylation of the SOCS‑1 gene. Stable hepatocyte cell lines expressing the HBx gene (pcDNA‑X/QSG7701) or an empty gene (pcDNA3.0/QSG7701) were established. Reverse transcription quantitative polymerase chain reaction (PCR) was used to detect the mRNA expression levels of DNMT3A/3B and SOCS‑1. Immunohistochemistry was used to detect the protein expression of DNMT3A/3B. Methylation‑specific PCR (MSP) was used to detect the methylation status of the SOCS‑1 gene promoter. The mRNA and protein expression levels of DNMT3A/3B were significantly higher in the pcDNA‑X/QSG7701‑transfected cells, compared with those in the pcDNA3.0/QSG7701 or non‑transfected QSG7701 cells (P<0.05), whereas the relative mRNA expression of SOCS‑1 was significantly lower in the pcDNA‑X/QSG7701 cells compared with the pcDNA3.0/QSG7701 and non‑transfected QSG7701 cells (F=19.6; P<0.05). Western blot analysis showed that the protein expression of SOCS‑1 was significantly lower in the pcDNA‑X/QSG7701 cells, compared with the pcDNA3.0/QSG7701 or non‑transfected QSG7701 cells (F=19.4; P<0.05). The results of the MSP analysis showed that SOCS‑1 promoter region methylation was present only in the pcDNA‑X/QSG7701 cells. The HBV‑X gene upregulated the mRNA and protein expression levels of DNMT3A/3B, downregulated the expression of SOCS‑1 and increased SOCS‑1 gene promoter CpG island methylation. This may provide a potential explanation of the mechanism underlying HBx-associated hepatocellular carcinoma.

Silenced suppressor of cytokine signaling 1 (SOCS1) enhances the maturation and antifungal immunity of dendritic cells in response to Candida albicans in vitro

Dendritic cells (DCs) are known to play an important role in initiating and orchestrating antimicrobial immunity. Given the fact that candidiasis appears often in immunocompromised patients, it seems plausible that DCs hold the key to new antifungal strategies. One possibility to enhance the potency of DC-based immunotherapy is to silence the negative immunoregulatory pathways through the ablation suppressor of cytokine signaling suppressor 1 (SOCS1). Here, we deliver small interfering RNA (siRNA) against SOCS1 into murine bone marrow DCs, and as a consequence, we investigate the maturation/action of DCs and the subsequent T cell response after exposure to C. albicans. Our results show that the maturation of DCs (i.e., expressions of CD80, CD40, CD86, and MHC II) are significantly increased in the silenced SOCS1 treatment group after exposure to C. albicans. As a result, suppression of the SOCS1 promotes the greatest expression of IFN-γ and IL-12, and reduces IL-4 secretions, which induce CD4⁺ cell Th1 differentiation but inactivate Th2 cell development. The responses of IL-6 and TNF-β consist of up-regulation in the presence of C. albicans, but this is not specific to SOCS1 silencing, suggesting that these cytokines are not regulated by the SOCS1 gene in fungal infections. We find Th17 differentiation is unchanged regardless of SOCS1 inhibition. The increase in phagocytosis and killing of C. albicans in SOCS1 gene-treated DCs indicate a role for this cytokine suppressor in innate immunity as well. In conclusion, our findings support the view that SOCS1 protein is a critical inhibitory molecule for controlling cytokine response and antigen presentation by DCs, thereby regulating the magnitude of innate and adaptive immunities by generating IFN-γ-production T cells (Th1)—but not Th17—from naïve CD4⁺ T cells. Our study demonstrates that SOCS1 siRNA can serve as a useful vehicle to modulate the function of DCs against C. albicans infection.

Galectins regulate the inflammatory response in airway epithelial cells exposed to microbial neuraminidase by modulating the expression of SOCS1 and RIG1

Influenza patients frequently display increased susceptibility to Streptococcus pneumoniae co-infection and sepsis, the prevalent cause of mortality during influenza pandemics. However, the detailed mechanisms by which an influenza infection predisposes patients to suffer pneumococcal pneumonia are not fully understood. A murine model for influenza infection closely reflects the observations in human patients, since if the animals that have recovered from influenza A virus (IAV) sublethal infection are challenged with S. pneumoniae, they undergo a usually fatal uncontrolled cytokine response. We have previously demonstrated both in vitro and in vivo that the expression and secretion of galectin-1 (Gal1) and galectin-3 (Gal3) are modulated during IAV infection, and that the viral neuraminidase unmasks galactosyl moieties in the airway epithelia. In this study we demonstrate in vitro that the binding of secreted Gal1 and Gal3 to the epithelial cell surface modulates the expression of SOCS1 and RIG1, and activation of ERK, AKT or JAK/STAT1 signaling pathways, leading to a disregulated expression and release of pro-inflammatory cytokines. Our results suggest that the activity of the viral and pneumococcal neuraminidases on the surface of the airway epithelial cells function as a "danger signal" that leads to rapid upregulation of SOCS1 expression to prevent an uncontrolled inflammatory response. The binding of extracellular Gal1 or Gal3 to the galactosyl moieties unmasked on the surface of airway epithelial cells can either "fine-tune" or severely disregulate this process, respectively, the latter potentially leading to hypercytokinemia.

Endogenous galectin-3 expression levels modulate immune responses in galectin-3 transgenic mice

Galectin-3 (Gal-3), a β-galactoside-binding mammalian lectin, is involved in cancer progression and metastasis. However, there is an unmet need to identify the underlying mechanisms of cancer metastasis mediated by endogenous host galectin-3. Galectin-3 is also known to be an important regulator of immune responses. The present study was aimed at analysing how expression of endogenous galectin-3 regulates host immunity and lung metastasis in B16F10 murine melanoma model. Transgenic Gal-3(+/-) (hemizygous) and Gal-3(-/-) (null) mice exhibited decreased levels of Natural Killer (NK) cells and lower NK mediated cytotoxicity against YAC-1 tumor targets, compared to Gal-3(+/+) (wild-type) mice. On stimulation, Gal-3(+/-) and Gal-3(-/-) mice splenocytes showed increased T cell proliferation than Gal-3(+/+) mice. Intracellular calcium flux was found to be lower in activated T cells of Gal-3(-/-) mice as compared to T cells from Gal-3(+/+) and Gal-3(+/-) mice. In Gal-3(-/-) mice, serum Th1, Th2 and Th17 cytokine levels were found to be lowest, exhibiting dysregulation of pro-inflammatory and anti-inflammatory cytokines balance. Marked decrease in serum IFN-γ levels and splenic IFN-γR1 (IFN-γ Receptor 1) expressing T and NK cell percentages were observed in Gal-3(-/-) mice. On recombinant IFN-γ treatment of splenocytes in vitro, Suppressor of Cytokine Signaling (SOCS) 1 and SOCS3 protein expression was higher in Gal-3(-/-) mice compared to that in Gal-3(+/+) and Gal-3(+/-) mice; suggesting possible attenuation of Signal Transducer and Activator of Transcription (STAT) 1 mediated IFN-γ signaling in Gal-3(-/-) mice. The ability of B16F10 melanoma cells to form metastatic colonies in the lungs of Gal-3(+/+) and Gal-3(-/-) mice remained comparable, whereas it was found to be reduced in Gal-3(+/-) mice. Our data indicates that complete absence of endogenous host galectin-3 facilitates lung metastasis of B16F10 cells in mice, which may be contributed by dysregulated immune responses resulting from decreased NK cytotoxicity, disturbed serum Th1, Th2, Th17 cytokine milieu, reduced serum IFN-γ levels and attenuation of splenic STAT1 mediated IFN-γ signalling in Gal-3(-/-) mice.

Estrogen receptor 2b deficiency impairs the antiviral response of zebrafish

Although several studies have demonstrated the ability of some endocrine disruptive chemicals (EDCs) to alter the physiology of zebrafish, the immune-reproductive interaction has received little attention in this species. In this study, we used a homozygous line carrying an insertion of 8 amino acids in the ligand-binding domain of the estrogen receptor 2b gene (esr2b) to further understand the role of estrogen signaling on innate immunity. Adult mutant fish showed distorted sexual ratios related with alterations in testicular morphology and supraphysiological testosterone and 17β-estradiol (E2) levels. Immunity-wise, although esr2b mutant fish showed unaltered antibacterial responses, they were unable to mount an effective antiviral response upon viral challenge. RT-qPCR analysis demonstrated that mutant fish were able to induce the genes encoding major antiviral molecules, including Ifnphi1, Ifnphi2, Infphi3, Mxb and Mxc, and the negative feedback regulator of cytokine signaling Socs1. Notably, although esr2b mutant larvae showed a similar resistance to SVCV infection to their wild type siblings, waterborne E2 increased their viral susceptibility. Similarly, the exposure of adult wild type zebrafish to E2 also resulted in increased susceptibility to SVCV infection. Finally, the administration of recombinant Ifnphi1 hardly reversed the higher viral susceptibility of esr2b mutant zebrafish, suggesting that elevated socs1 levels impair Ifn signaling. All together, these results uncover an important role for E2 and Esr signaling in the fine-tuning of sexual hormone balance and the antiviral response of vertebrates.

Functional Impairment of Myeloid Dendritic Cells during Advanced Stage of HIV-1 Infection: Role of Factors Regulating Cytokine Signaling

INTRODUCTION

Severely immunocompromised state during advanced stage of HIV-1 infection has been linked to functionally defective antigen presentation by dendritic cells (DCs). The molecular mechanisms behind DC impairment are still obscure. We investigated changes in DC function and association of key regulators of cytokine signaling during different stages of HIV-1 infection and following antiretroviral therapy (ART).

METHODS

Phenotypic and functional characteristics of circulating myeloid DCs (mDCs) in 56 ART-naive patients (23 in early and 33 in advanced stage of disease), 36 on ART and 24 healthy controls were evaluated. Sixteen patients were studied longitudinally prior-to and 6 months after the start of ART. For functional studies, monocyte-derived DCs (Mo-DCs) were evaluated for endocytosis, allo-stimulation and cytokine secretion. The expression of suppressor of cytokine signaling (SOCS)-1 and other regulators of cytokine signaling was evaluated by real-time RT-PCR.

RESULTS

The ability to respond to an antigenic stimulation was severely impaired in patients in advanced HIV-1 disease which showed partial recovery in the treated group. Mo-DCs from patients with advanced HIV-disease remained immature with low allo-stimulation and reduced cytokine secretion even after TLR-4 mediated stimulation ex-vivo. The cells had an increased expression of negative regulatory factors like SOCS-1, SOCS-3, SH2-containing phosphatase (SHP)-1 and a reduced expression of positive regulators like Janus kinase (JAK)2 and Nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB)1. A functional recovery after siRNA mediated silencing of SOCS-1 in these mo-DCs confirms the role of negative regulatory factors in functional impairment of these cells.

CONCLUSIONS

Functionally defective DCs in advanced stage of HIV-1 infection seems to be due to imbalanced state of negative and positive regulatory gene expression. Whether this is a cause or effect of increased viral replication at this stage of disease, needs further investigation. The information may be useful in design of novel therapeutic targets for better management of disease.

NMAAP1 Expressed in BCG-Activated Macrophage Promotes M1 Macrophage Polarization

Macrophages are divided into two subpopulations: classically activated macrophages (M1) and alternatively activated macrophages (M2). BCG (Bacilli Calmette-GuC)rin) activates disabled naC/ve macrophages to M1 macrophages, which act as inflammatory, microbicidal and tumoricidal cells through cell-cell contact and/or the release of soluble factors. Various transcription factors and signaling pathways are involved in the regulation of macrophage activation and polarization. We discovered that BCG-activated macrophages (BAM) expressed a new molecule, and we named it Novel Macrophage Activated Associated Protein 1 (NMAAP1). The current study found that the overexpression of NMAAP1 in macrophages results in M1 polarization with increased expression levels of M1 genes, such as inducible nitric oxide synthase (iNOS), tumor necrosis factor alpha (TNF-N1), Interleukin 6 (IL-6), Interleukin 12 (IL-12), Monocyte chemoattractant protein-1 (MCP-1) and Interleukin-1 beta (IL-1N2), and decreased expression of some M2 genes, such as Kruppel-like factor 4 (KLF4) and suppressor of cytokine signaling 1 (SOCS1), but not other M2 genes, including arginase-1 (Arg-1), Interleukin (IL-10), transforming growth factor beta (TGF-N2) and found in inflammatory zone 1 (Fizz1). Moreover, NMAAP1 overexpression in the RAW264.7 cell line increased cytotoxicity against MCA207 tumor cells, which depends on increased inflammatory cytokines rather than cell-cell contact. NMAAP1 also substantially enhanced the phagocytic ability of macrophages, which implies that NMAAP1 promoted macrophage adhesive and clearance activities. Our results indicate that NMAAP1 is an essential molecule that modulates macrophages phenotype and plays an important role in macrophage tumoricidal functions.

Suppressor of cytokine signaling 1-modulated metalloproteinases and tissue inhibitor of metalloproteinase in pulmonary fibrosis

An imbalance between metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) affects the synthesis and degradation of extracellular matrix molecules, which have an important role in the pathogenesis of pulmonary fibrosis. Lower mRNA expression levels of suppressor of cytokine signaling 1 (SOCS1) are present in fibroblasts from the lungs of pulmonary fibrosis. However, little is currently known regarding the precise role of SOCS1 has in idiopathic pulmonary fibrosis (IPF). The present study examined the expression levels of MMPs and TIMPs in A549 human epithelial lung carcinoma cells and human embryonic lung fibroblasts (HLFs) stimulated with transforming growth factor‑β1 (TGF‑β1) in conditions of deficiency and over‑expression of SOCS1, by transfection with a lentivirus. Overexpression of SOCS1 in A549 cells and HLFs significantly inhibited the mRNA expression levels of MMP‑1, MMP‑2 and MMP‑9 (P<0.05). In the A549 cells lacking SOCS1 expression, the mRNA expression levels of TIMP‑1 were significantly higher compared with the control groups (P<0.01). Overexpression of SOCS1 partially reversed these changes. The expression levels of TIMP‑1 in the HLFs with an overexpression of SOCS1 were decreased, as compared with the SOCS1‑deficient HLFs following TGF‑β1 stimulation; however, this finding was not significant (0.24±0.01 vs. 0.53±0.02, P>0.05). The expression levels of TIMP‑2 were significantly lower in the cells overexpressing SOCS1. Conversely, the mRNA expression levels of TIMP‑2 were significantly higher in the SOCS1‑deficient A549 cells, as compared with all of the other groups (P<0.05). TIMP‑4 expression levels were elevated in the A549 cells and HLFs transfected with the SOCS1‑deficient lentivirus. The expression levels of TIMP‑4 were significantly lower in the groups overexpressing SOCS1, as compared with the other groups. These results suggest that SOCS1 may act as a suppressor of pulmonary fibrosis, by reducing the expression of MMPs and TIMPs. Therefore, SOCS1 may be a target for IPF treatment.

MiR-19a targets suppressor of cytokine signaling 1 to modulate the progression of neuropathic pain

PURPOSE

We aimed to investigate whether miR-19a is associated with neuropathic pain and elucidate the underlying regulatory mechanism.

METHODS

We established a neuropathic pain model of bilateral chronic constriction injury (bCCI). Then bCCI rats were injected with mo-miR-19a, siR-SOCS1 or blank expression vector through a microinjection syringe via an intrathecal catheter on 3 day before surgery and after surgery. Behavioral tests, such as mechanical allodynia, thermal hyperalgesia and acetone induced cold allodynia, were performed to evaluate the pain threshold. Besides, quantitative real-time polymerase chain reaction (qRT-PCR) was performed to determine the expression of miR-19a and western blotting was carried out to measure the expression of SOCS1.

RESULTS

miR-19a expression levels were markedly increased in neuropathic pain models. Moreover, miR-19a significantly attenuated mechanical allodynia and thermal hyperalgesia, and similar results were obtained after knockdown of SOCS1 expression. However, miR-19a markedly increased the times that the rats appeared a sign of cold allodynia, and knockdown of SOCS1 expression had similar effects. Besides, the results of bioinformatics analysis and western blotting analysis were all confirmed that SOCS1 was a direct target of miR-19a in neuropathic pain models.

CONCLUSIONS

Our finding indicate that SOCS1 is a direct target of miR-19a in neuropathic pain rats and miR-19a may play a critical role in regulating of neuropathic pain via targeting SOCS1.

GH signaling in human adipose and muscle tissue during 'feast and famine': amplification of exercise stimulation following fasting compared to glucose administration

OBJECTIVE

Fasting and exercise stimulates, whereas glucose suppresses GH secretion, but it is uncertain how these conditions impact GH signaling in peripheral tissues. To test the original 'feast and famine hypothesis' by Rabinowitz and Zierler, according to which the metabolic effects of GH are predominant during fasting, we specifically hypothesized that fasting and exercise act in synergy to increase STAT-5b target gene expression.

DESIGN AND METHODS

Eight healthy men were studied on two occasions in relation to a 1 h exercise bout: i) with a concomitant i.v. glucose infusion ('feast') and ii) after a 36 h fast ('famine'). Muscle and fat biopsy specimens were obtained before, immediately after, and 30 min after exercise.

RESULTS

GH increased during exercise on both examination days and this effect was amplified by fasting, and free fatty acid (FFA) levels increased after fasting. STAT-5b phosphorylation increased similarly following exercise on both occasions. In adipose tissue, suppressors of cytokine signaling 1 (SOCS1) and SOCS2 were increased after exercise on the fasting day and both fasting and exercise increased cytokine inducible SH2-containing protein (CISH). In muscle, SOCS2 and CISH mRNA were persistently increased after fasting. Muscle SOCS1, SOCS3, and CISH mRNA expression increased, whereas SOCS2 decreased after exercise on both examination days.

CONCLUSIONS

This study demonstrates that fasting and exercise act in tandem to amplify STAT-5b target gene expression (SOCS and CISH) in adipose and muscle tissue in accordance with the 'feast and famine hypothesis'; the adipose tissue signaling responses, which hitherto have not been scrutinized, may play a particular role in promoting FFA mobilization.

Type III Interferon Induces Distinct SOCS1 Expression Pattern that Contributes to Delayed but Prolonged Activation of Jak/STAT Signaling Pathway: Implications for Treatment Non-Response in HCV Patients

Suppressor of cytokine signaling 1 (SOCS1) has long been thought to block type I interferon signaling. However, IFN-λ, a type III IFN with limited receptor expression in hepatic cells, efficiently inhibits HCV (Hepatitis C virus) replication in vivo with potentially less side effects than IFN-α. Previous studies demonstrated that type I and type III activated Janus kinase/signal transducer and activator of transcription (Jak/STAT) signaling pathway differently, with delayed but prolonged activation by IFN-λ stimulation compared to IFNα/β. However, the molecular mechanisms underlying this observation is not well understood. Here, we found that there are distinct differences in SOCS1 expression patterns in Huh-7.5.1 cells following stimulation with IFN-α and IFN-λ. IFN-λ induced a faster but shorter expression of SOCS1. Furthermore, we confirmed that SOCS1 over-expression abrogates anti-HCV effect of both IFN-α and IFN-λ, leading to increased HCV RNA replication in both HCV replicon cells and JFH1 HCV culture system. In line with this, SOCS1 over-expression inhibited STAT1 phosphorylation, attenuated IFN-stimulated response elements (ISRE) reporter activity, and blocked IFN-stimulated genes (ISGs) expression. Finally, we measured SOCS1 mRNA expression levels in peripheral blood mononuclear cells (PBMCs) with or without IFN-α treatment from 48 chronic hepatitis C patients and we found the baseline SOCS1 expression levels are higher in treatment non-responders than in responders before IFN-α treatment. Taken together, SOCS1 acts as a suppressor for both type I and type III IFNs and is negatively associated with sustained virological response (SVR) to IFN-based therapy in patients with HCV. More importantly, faster but shorter induction of SOCS1 by IFN-λ may contribute to delayed but prolonged activation of IFN signaling and ISG expression kinetics by type III IFN.

Adenovirus-mediated transfer of the SOCS-1 gene to mouse lung confers protection against hyperoxic acute lung injury

Suppressor of cytokine signaling-1 (SOCS-1) is a member of the suppressor of cytokine signaling family of proteins and an inhibitor of interleukin-6 (IL-6) signaling. SOCS-1 has been shown to protect cells from cellular damage and apoptosis induced by tumor necrosis factor (TNF), lipopolysaccharide (LPS), and interferon gamma (IL-γ). However, it is not known whether increased SOCS-1 is protective during pulmonary oxidative stress. Therefore, we hypothesized that increased SOCS-1 in the lungs of mice would be protective in the setting of hyperoxic lung injury. We administered SOCS-1 adenovirus (Ad-SOCS-1) intratracheally into the lungs and exposed the mice to 100% O2. Mice infected with GFP adenovirus (Ad-GFP) were used as controls. Mice treated with Ad-SOCS-1 had enhanced survival in 100% oxygen compared to Ad-GFP-administered mice. After 3 days of hyperoxia, Ad-GFP mice were ill and tachypnic and died after 4 days. In contrast, all Ad-SOCS-1-treated mice survived for at least 6 days in hyperoxia and 80% survived beyond 7 days. Ad-SOCS-1 transfection protected mouse lungs from injury as indicated by lower lung wet/dry weight, alveolar-capillary protein leakage, reduced infiltration of inflammatory cells, and lower content of thiobarbituric acid-reactive substances in lung homogenate. Our results also indicated that Ad-SOCS-1 significantly inhibits hyperoxia-induced ASK-1 (apoptosis signal-regulating kinase 1) expression. Taken together, these findings show that increased expression of adenovirus-mediated SOCS-1 in the lungs of mice significantly protects against hyperoxic lung injury.

HIV-1 Tat Protein Induces Production of Proinflammatory Cytokines by Human Dendritic Cells and Monocytes/Macrophages through Engagement of TLR4-MD2-CD14 Complex and Activation of NF-κB Pathway

We recently reported that the human immunodeficiency virus type-1 (HIV-1) Tat protein induced the expression of programmed death ligand-1 (PD-L1) on dendritic cells (DCs) through a TLR4 pathway. However, the underlying mechanisms by which HIV-1 Tat protein induces the abnormal hyper-activation of the immune system seen in HIV-1 infected patients remain to be fully elucidated. In the present study, we report that HIV-1 Tat protein induced the production of significant amounts of the pro-inflammatory IL-6 and IL-8 cytokines by DCs and monocytes from both healthy and HIV-1 infected patients. Such production was abrogated in the presence of anti-TLR4 blocking antibodies or soluble recombinant TLR4-MD2 as a decoy receptor, suggesting TLR4 was recruited by Tat protein. Tat-induced murine IL-6 and CXCL1/KC a functional homologue of human IL-8 was abolished in peritoneal macrophages derived from TLR4 KO but not from Wt mice, confirming the involvement of the TLR4 pathway. Furthermore, the recruitment of TLR4-MD2-CD14 complex by Tat protein was demonstrated by the activation of TLR4 downstream pathways including NF-κB and SOCS-1 and by down-modulation of cell surface TLR4 by endocytosis in dynamin and lipid-raft-dependent manners. Collectively, these findings demonstrate, for the first time, that HIV-1 Tat interacts with TLR4-MD2-CD14 complex and activates the NF-κB pathway, leading to overproduction of IL-6 and IL-8 pro-inflammatory cytokines by myeloid cells from both healthy and HIV-1 infected patients. This study reveals a novel mechanism by which HIV-1, via its early expressed Tat protein, hijacks the TLR4 pathway, hence establishing abnormal hyper-activation of the immune system.

Bacterial extract OM-85 BV protects mice against experimental chronic rhinosinusitis

OBJECTIVES

To investigate the therapeutic effects of OM-85 BV as an adjunctive treatment on experimental chronic rhinosinusitis (CRS) in mice.

METHODOLOGY

Female BALB/c mice aged 8-12 weeks were sensitized and administrated by intranasal Aspergillus fumigatis (AF) three times per week for 1 week, 3 weeks, 2 months and 3 months (n = 10 each time point). The mice were randomly and equally assigned to four groups: normal control group, model group, OM-85-BV plus amoxicillin group, and isolated amoxicillin group. Inflammatory changes were determined by hematoxylin-eosin (HE) staining. The expression levels of suppressor of cytokine signaling (SOCS) 1, SOCS3, tumor necrosis factor (TNF)-α, and interferon (IFN)-γ in samples were assessed by using real-time PCR (RT-PCR) and Western blotting.

RESULTS

There were significantly inflammatory and structural changes between the model and other groups. Compared to the model group, the mRNA expression levels of SOCS1, SOCS3, TNF-α, and IFN-γ were significantly decreased in OM-85-BV plus amoxicillin group and isolated amoxicillin group, along with the protein levels.

CONCLUSION

The bacterial extract OM-85 BV is a low-cost alternatively adjunctive drug to treat CRS with simple oral administration, good safety, and few side effects.

Depletion of suppressor of cytokine signaling-1a causes hepatic steatosis and insulin resistance in zebrafish

Suppressor of cytokine signaling-1a (SOCS1a) is a member of the suppressor of cytokine signaling family, a group of related molecules that mediate the negative regulation of the JAK-STAT pathway. Here, we depleted SOCS1a using the transcription activator-like (TAL) effector nuclease (TALEN) technique to understand its physiological roles in zebrafish. Although elevated levels of JAK-STAT5 activation and erythropoiesis have been observed in socs1a-deficient zebrafish, these animals exhibited normal growth during the early stages. Socs1a-deficient zebrafish began to grow slowly with certain mortalities after 20 days postfertilization (dpf), whereas the heterozygous socs1a-deficient zebrafish exhibited enhanced somatic growth. Decreased adiposity, hepatic steatosis, and insulin resistance were observed in our socs1a-deficient adult zebrafish, which is similar to the lipodystrophy phenotypes observed in mammals. Comparative transcriptomic analyses revealed elevated levels of gluconeogenesis, lipolysis, and hypoxia-inducible response and decreased activities of lipogenesis and glycolysis in the hepatocytes of socs1a-deflicient adult zebrafish. Evident mitochondrial dysfunction has also been observed in hepatocytes from socs1a-deficient zebrafish. Taken together, our results suggest that the negative regulatory roles of SOCS1a on JAK-STAT5 signaling may be involved in the suppression of the erythropoiesis and growth hormone activities, which was also reflected in the enhanced somatic growth performance observed in the heterozygous socs1a-deficient fish. The differences in the effects caused by SOCS1a depletion on insulin sensitivity, lipid metabolism, and inflammatory responses between zebrafish and mammalian models observed here may reflect differences between the functional mechanisms of SOCS members in terrestrial mammals and aquatic teleosts.

Diphlorethohydroxycarmalol inhibits interleukin-6 production by regulating NF-κB, STAT5 and SOCS1 in lipopolysaccharide-stimulated RAW264.7 cells

Diphlorethohydroxycarmalol (DPHC) is a phlorotannin compound isolated from Ishige okamuarae, a brown alga. This study was conducted to investigate the anti-inflammatory effect and action mechanism of DPHC in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages. We found that DPHC strongly reduces the production of interleukin 6 (IL-6), but not that of tumor necrosis factor-alpha (TNF-α) induced by LPS. DPHC (12.5 and 100 μM) suppressed the phosphorylation and the nuclear translocation of NF-kappaB (NF-κB), a central signaling molecule in the inflammation process induced by LPS. The suppressor of cytokine signaling 1 (SOCS1) is a negative feedback regulator of Janus kinase (Jak)-signal transducer and activator of transcription (STAT) signaling. In this study, DPHC inhibited STAT5 expression and upregulated that of SOCS1 at a concentration of 100 μM. Furthermore, N-tosyl-l-phenylalanine chloromethyl ketone (TPCK) (a specific NF-κB inhibitor) and JI (a specific Jak2 inhibitor) reduced the production of IL-6, but not that of tumor necrosis factor-alpha (TNF-α) in LPS-stimulated RAW 264.7 macrophages. These findings demonstrate that DPHC inhibits IL-6 production via the downregulation of NF-κB and Jak2-STAT5 pathway and upregulation of SOCS1.

Interleukin 23 produced by myeloid dendritic cells contributes to T-cell dysfunction in HIV type 1 infection by inducing SOCS1 expression

The mechanism of myeloid dendritic cell (mDC)-mediated impaired T-cell function was investigated during human immunodeficiency virus type 1 (HIV-1) infection. HIV or gp120 were found to inhibit lipopolysaccharide-induced mDC maturation and cause defects in allogeneic T-cell proliferation, interleukin 2 and interferon γ (IFN-γ) production, and phosphorylated STAT1 expression. gp120-treated mDCs downregulated autologous T-cell proliferation and IFN-γ production against a peptide pool consisting of cytomegalovirus, Epstein-Barr virus, and influenza virus (CEF). These T-cell defects were associated with a decrease in production of the T-helper type 1-polarizing cytokine interleukin 12p70 and an increase in interleukin 23 (IL-23) production by gp120-treated mDCs. gp120-induced IL-23 upregulated suppressor of cytokine signaling 1 (SOCS1) protein in T cells, which inhibited IFN-γ production and killing of CEF-pulsed monocytes. These effector functions were recovered by silencing SOCS1 in T cells. Furthermore, we observed IL-23-induced SOCS1 binding to the IFN-γ transcription complex. These results identify SOCS1 as a novel target to improve the immune function in HIV-infected persons.

MicroRNA 21 is a homeostatic regulator of macrophage polarization and prevents prostaglandin E2-mediated M2 generation

Macrophages dictate both initiation and resolution of inflammation. During acute inflammation classically activated macrophages (M1) predominate, and during the resolution phase alternative macrophages (M2) are dominant. The molecular mechanisms involved in macrophage polarization are understudied. MicroRNAs are differentially expressed in M1 and M2 macrophages that influence macrophage polarization. We identified a role of miR-21 in macrophage polarization, and found that cross-talk between miR-21 and the lipid mediator prostaglandin E₂ (PGE₂) is a determining factor in macrophage polarization. miR-21 inhibition impairs expression of M2 signature genes but not M1 genes. PGE₂ and its downstream effectors PKA and Epac inhibit miR-21 expression and enhance expression of M2 genes, and this effect is more pronounced in miR-21-/- cells. Among potential targets involved in macrophage polarization, we found that STAT3 and SOCS1 were enhanced in miR-21-/- cells and further enhanced by PGE₂. We found that STAT3 was a direct target of miR-21 in macrophages. Silencing the STAT3 gene abolished PGE₂-mediated expression of M2 genes in miR-21-/- macrophages. These data shed light on the molecular brakes involved in homeostatic macrophage polarization and suggest new therapeutic strategies to prevent inflammatory responses.

The early induction of suppressor of cytokine signaling 1 and the downregulation of toll-like receptors 7 and 9 induce tolerance in costimulated macrophages

Toll-like receptors (TLR) 7 and 9 transduce a cellular signal through the MyD88-dependent pathway and induce the production of inflammatory mediators against microbial nucleotide components. The repeated stimulation of TLR4 leads to endotoxin tolerance, but the molecular mechanisms of tolerance induced through the costimulation of individual TLR has not yet been established, although endosomal TLRs share signaling pathways with TLR4. In the present study, mouse macrophages were simultaneously stimulated with the TLR7 agonist, gardiquimod (GDQ), and the TLR9 agonist, CpG ODN 1826, to examine the mechanism and effector functions of macrophage tolerance. Compared with individual stimulation, the costimulation of both TLRs reduced the secretion of TNF-α and IL-6 through the delayed activation of the NF-κB pathway; notably, IL-10 remained unchanged in costimulated macrophages. This tolerance reflected the early induction of suppressor of cytokine signaling-1 (SOCS-1), according to the detection of elevated TNF-α secretion and restored NF-κB signaling in response to the siRNA-mediated abrogation of SOCS-1 signaling. In addition, the restimulation of each TLRs using the same ligand significantly reduced the expression of both TLRs in endosomes. These findings revealed that the costimulation of TLR7 and TLR9 induced macrophage tolerance via SOCS-1, and the restimulation of each receptor or both TLR7 and TLR9 downregulated TLR expression through a negative feedback mechanisms that protects the host from excessive inflammatory responses. Moreover, the insufficient and impaired immune response in chronic viral infection might also reflect the repeated and simultaneous stimulation of those endosomal TLRs.

Expression of suppressor of cytokine signaling 1 (SOCS1) impairs viral clearance and exacerbates lung injury during influenza infection

Suppressor of cytokine signaling (SOCS) proteins are inducible feedback inhibitors of cytokine signaling. SOCS1^−/− mice die within three weeks postnatally due to IFN-γ-induced hyperinflammation. Since it is well established that IFN-γ is dispensable for protection against influenza infection, we generated SOCS1^−/−IFN-γ^−/− mice to determine whether SOCS1 regulates antiviral immunity in vivo. Here we show that SOCS1^−/−IFN-γ^−/− mice exhibited significantly enhanced resistance to influenza infection, as evidenced by improved viral clearance, attenuated acute lung damage, and consequently increased survival rates compared to either IFN-γ^−/− or WT animals. Enhanced viral clearance in SOCS1^−/−IFN-γ^−/− mice coincided with a rapid onset of adaptive immune responses during acute infection, while their reduced lung injury was associated with decreased inflammatory cell infiltration at the resolution phase of infection. We further determined the contribution of SOCS1-deficient T cells to antiviral immunity. Anti-CD4 antibody treatment of SOCS1^−/−IFN-γ^−/− mice had no significant effect on their enhanced resistance to influenza infection, while CD8⁺ splenocytes from SOCS1^−/−IFN-γ^−/− mice were sufficient to rescue RAG1^−/− animals from an otherwise lethal infection. Surprisingly, despite their markedly reduced viral burdens, RAG1^−/− mice reconstituted with SOCS1^−/−IFN-γ^−/− adaptive immune cells failed to ameliorate influenza-induced lung injury. In conclusion, in the absence of IFN-γ, the cytoplasmic protein SOCS1 not only inhibits adaptive antiviral immune responses but also exacerbates inflammatory lung damage. Importantly, these detrimental effects of SOCS1 are conveyed through discrete cell populations. Specifically, while SOCS1 expression in adaptive immune cells is sufficient to inhibit antiviral immunity, SOCS1 in innate/stromal cells is responsible for aggravated lung injury.

Cytokines are critical in regulating the balance between protective immunity and detrimental inflammation during influenza infection. Suppressor of cytokine signaling (SOCS) proteins are inducible feedback inhibitors of cytokine signaling. Using gene-deficient and infectious animal models, we determined how SOCS1 regulates immune defense against influenza infection. We show that the intracellular protein SOCS1 not only inhibits adaptive antiviral immune responses but also exacerbates inflammatory lung damage. These detrimental effects of SOCS1 are conveyed through discrete cell populations. Specifically, while SOCS1 expression in adaptive immune cells is sufficient to inhibit antiviral immunity, SOCS1 in innate/stromal cells is responsible for aggravated lung injury. To our knowledge, there is no report showing the regulatory role of SOCS1 during the course of influenza infection, and importantly, no evidence directly linking SOCS1 with excessive inflammation in other infectious disease models. The distinct and non-competing detrimental roles of SOCS1, as revealed in this study, make it an appealing target in the design of effective immunotherapies for combating influenza infection.

Suppression of microRNA-155 attenuates neuropathic pain by regulating SOCS1 signalling pathway

Chronic neuropathic pain is an unfavourable pathological pain characterised by allodynia and hyperalgesia which has brought considerable trouble to people's physical and mental health, but effective therapeutics are still lacking. MicroRNAs (miRNAs) have been widely studied in the development of neuropathic pain and neuronal inflammation. Among various miRNAs, miR-155 has been widely studied. It is intensively involved in regulating inflammation-associated diseases. However, the role of miR-155 in regulating neuropathic pain development is poorly understood. In the present study, we aimed to investigate whether miR-155 is associated with neuropathic pain and delineate the underlying mechanism. Using a neuropathic pain model of chronic constriction injury (CCI), miR-155 expression levels were markedly increased in the spinal cord. Inhibition of miR-155 significantly attenuated mechanical allodynia, thermal hyperalgesia and proinflammatory cytokine expression. We also demonstrated that miR-155 directly bound with the 3'-untranslated region of the suppressor of cytokine signalling 1 (SOCS1). The expression of SOCS1 significantly decreased in the CCI rat model, but this effect could be reversed by miR-155 inhibition. Furthermore, knockdown of SOCS1 abrogated the inhibitory effects of miR-155 inhibition on neuropathic development and neuronal inflammation. Finally, we demonstrated that inhibition of miR-155 resulted in the suppression of nuclear factor-κB and p38 mitogen-activated protein kinase activation by mediating SOCS1. Our data demonstrate the critical role of miR-155 in regulating neuropathic pain through SOCS1, and suggest that miR-155 may be an important and potential target in preventing neuropathic pain development.

CSN-associated USP48 confers stability to nuclear NF-κB/RelA by trimming K48-linked Ub-chains

Diligent balance of nuclear factor kappa B (NF-κB) activity is essential owing to NF-κB's decisive role in cellular processes including inflammation, immunity and cell survival. Ubiquitin/proteasome-system (UPS)-dependent degradation of activated NF-κB/RelA involves the cullin-RING-ubiquitin-ligase (CRL) ECS(SOCS1). The COP9 signalosome (CSN) controls ubiquitin (Ub) ligation by CRLs through the removal of the CRL-activating Ub-like modifier NEDD8 from their cullin subunits and through deubiquitinase (DUB) activity of associated DUBs. However, knowledge about DUBs involved in the regulation of NF-κB activity within the nucleus is scarce. In this study we observed that USP48, a DUB of hitherto ill-defined function identified through a siRNA screen, associates with the CSN and RelA in the nucleus. We show that USP48 trims rather than completely disassembles long K48-linked free and substrate-anchored Ub-chains, a catalytic property only shared with ataxin-3 (Atx3) and otubain-1 (OTU1), and that USP48 Ub-chain-trimming activity is regulated by casein-kinase-2 (CK2)-mediated phosphorylation in response to cytokine-stimulation. Functionally, we demonstrate for the first time the CSN and USP48 to cooperatively stabilize the nuclear pool of RelA, thereby facilitating timely induction and shutoff of NF-κB target genes. In summary, this study demonstrates that USP48, a nuclear DUB regulated by CK2, controls the UPS-dependent turnover of activated NF-κB/RelA in the nucleus together with the CSN. Thereby USP48 contributes to a timely control of immune responses.

[Regulation of Jinxin Oral Liquid for the expression of negative regulatory factor of TLR3 signaling pathway SOCS1 in RSV infected BALB/c mice]

OBJECTIVE

To investigate the regulation trend of Jinxin Oral Liquid (JXOL) on the expression of negative regulatory factor of TLR3 signaling pathway SOCS1 in the lung tissue of RSV infected BALB/c mice at different time points.

METHODS

Totally 75 BALB/c mice were randomly divided into 5 groups, i.e., the normal control group, the model group, the ribavirin group, the high dose JXOL group, and the equivalent dose JXOL group, 15 in each group. Each group had 3 intervention ways (I, II, and III) with 5 mice treated in each group. BALB/c mice were nasally infected with respiratory syncytial virus (RSV), and treated by different intervention ways. After intervention, mice were killed and their lung tissues were sampled, mRNA expression levels of RSV-M, SOCS1, and IFN-β were detected by Real time PCR. The expression of SOCSl at the protein level was detected by Western blot.

RESULTS

Compared with the normal control group, the mRNA expression level of SOCS1 and IFN-β, and the protein expression level of SOCS1 increased significantly in the model group intervened by intervention I and II (all P < 0.01), but the mRNA expression level of IFN-β decreased significantly in model group intervened by intervention III (P < 0.01). Compared with the model group, the mRNA expression level of RSV-M all significantly decreased in the high dose JXOL group and the equivalent dose JXOL group intervened by 3 intervention ways (all P < 0.01). The mRNA expression level of SOCS1 significantly decreased in the high dose JXOL group intervened by intervention I and III and the equivalent dose JXOL group intervened by 3 intervention ways (all P < 0.01). The mRNA expression level of IFN-β significantly decreased in the high dose JXOL group intervened by intervention I and II and the equivalent dose JXOL group intervened by intervention I (all P < 0.01), while it significantly increased in the high dose JXOL group intervened by intervention III and the equivalent dose JXOL group intervened by intervention III (all P < 0.01). The protein expression level of SOCS1 significantly decreased in the high dose JXOL group intervened by intervention I and the equivalent dose JXOL group intervened by 3 intervention ways (all P < 0.01), while it significantly increased in the high dose JXOL group intervened by intervention III (all P < 0.01). Compared with the high dose JXOL group, the mRNA expression level of RSV-M decreased significantly in the equivalent dose JXOL group intervened by intervention I and II (P < 0.01). The mRNA expression level of SOCS1 and IFN-β decreased significantly in the equivalent dose JXOL group intervened by intervention I (P < 0.01), but the mRNA expression level of IFN-β increased significantly in the equivalent dose JXOL group intervened by intervention II and III (all P < 0.01). The protein expression level of SOCS1 decreased significantly in the equivalent dose JXOL group intervened by 3 intervention ways (all P < 0.01).

CONCLUSIONS

JXOL could inhibit the expression of SOCS1 in the lung tissue of RSV infected BALB/c mice at different time points. Its regulatory effect might be associated with promoting the expression of interferon type I and further fighting against RSV.

Increased miR-155 expression in peripheral blood mononuclear cells of primary immune thrombocytopenia patients was correlated with serum cytokine profiles

We investigated the possible pathogenic role of a microRNA (miR-155) in primary immune thrombocytopenia (ITP). We used quantitative real-time PCR to determine the relative expression of miR-155 and SOCS1 (suppressor of cytokine signaling) mRNA in peripheral blood mononuclear cells (PBMCs) from 28 ITP patients and 28 healthy controls. Cytokine plasma levels were determined by ELISA. Possible associations between miR-155 levels and serum cytokine concentrations were assessed using Spearman or Pearson correlation analysis. Seven naive ITP patients were followed and the effects of medical treatment on miR-155 levels were assessed. Compared to healthy controls, ITP patients had increased miR-155 and decreased SOCS1 mRNA levels. ITP patients also had increased plasma IL-17A and decreased IL-4, IL-10 and TGF-β1 levels. miR-155 levels were negatively correlated with platelet counts, SOCS1 mRNA levels, and the plasma levels of IL-4, IL-10 and TGF-β1, but positively correlated with plasma IL-17A levels. Medical treatment for ITP decreased miR-155 levels. Thus, our results suggest that miR-155 might be involved in the pathogenesis of ITP by regulating cytokine profiles, which may be mediated by miR-155 targeting SOCS1.

MiR-122 directly inhibits human papillomavirus E6 gene and enhances interferon signaling through blocking suppressor of cytokine signaling 1 in SiHa cells

Human Papillomavirus (HPV) 16 infection is considered as one of the significant causes of human cervical cancer. The expression of the viral oncogenes like E6 and E7 play an important role in the development of the cancer. MiR-122 has been reported to exhibit a strong relationship with hepatitis viruses and take part in several tumor development, while the effects of miR-122 on HPV infection and the HPV viral oncogenes expression still remain unexplored. In this study, using RNAhybrid software, the potential binding sites between miR-122 and HPV16 E6 and E7 mRNAs were identified. Over and loss of miR-122 function showed that miR-122 could directly bind with HPV16 E6 mRNA and significantly inhibit its expression in SiHa cells, which was further confirmed by constructing the miR-122-E6-mu to eliminate the miR-122 binding effects with E6. The increase of the expression of type I interferon (IFN) and its classical effective molecules and the phosphorylation of signal transducers and activators of transcription (STAT1) protein indicated that miR-122 might enhance type I interferon in cervical carcinoma cells, which explained the significant reduction of HPV16 E7 and E6*I mRNA expression. This might be due to the binding between miR-122 and suppressor of cytokine signaling 1 (SOCS1) mRNA, which is the suppressor of interferon signaling pathway. Moreover, it was identified that the miR-122 binding position was nt359-nt375 in SOCS1 mRNA. Taken together, this study indicated that HPV16 could be effectively inhibited by miR-122 through both direct binding with E6 mRNA and promoting SOCS1-dependent IFN signaling pathway. Thus, miR-122 may serve as a new therapeutic option for inhibiting HPV infection.

Formal modelling of toll like receptor 4 and JAK/STAT signalling pathways: insight into the roles of SOCS-1, interferon-β and proinflammatory cytokines in sepsis

Sepsis is one of the major causes of human morbidity and results in a considerable number of deaths each year. Lipopolysaccharide-induced sepsis has been associated with TLR4 signalling pathway which in collaboration with the JAK/STAT signalling regulate endotoxemia and inflammation. However, during sepsis our immune system cannot maintain a balance of cytokine levels and results in multiple organ damage and eventual death. Different opinions have been made in previous studies about the expression patterns and the role of proinflammatory cytokines in sepsis that attracted our attention towards qualitative properties of TLR4 and JAK/STAT signalling pathways using computer-aided studies. René Thomas' formalism was used to model septic and non-septic dynamics of TLR4 and JAK/STAT signalling. Comparisons among dynamics were made by intervening or removing the specific interactions among entities. Among our predictions, recurrent induction of proinflammatory cytokines with subsequent downregulation was found as the basic characteristic of septic model. This characteristic was found in agreement with previous experimental studies, which implicate that inflammation is followed by immunomodulation in septic patients. Moreover, intervention in downregulation of proinflammatory cytokines by SOCS-1 was found desirable to boost the immune responses. On the other hand, interventions either in TLR4 or transcriptional elements such as NFκB and STAT were found effective in the downregulation of immune responses. Whereas, IFN-β and SOCS-1 mediated downregulation at different levels of signalling were found to be associated with variations in the levels of proinflammatory cytokines. However, these predictions need to be further validated using wet laboratory experimental studies to further explore the roles of inhibitors such as SOCS-1 and IFN-β, which may alter the levels of proinflammatory cytokines at different stages of sepsis.

Quercetagetin inhibits macrophage-derived chemokine in HaCaT human keratinocytes via the regulation of signal transducer and activator of transcription 1, suppressor of cytokine signalling 1 and transforming growth factor-β1

BACKGROUND

Inflammatory chemokines, such as macrophage-derived chemokine (MDC/CCL22), are elevated in the serum and lesioned skin of patients with atopic dermatitis (AD), and are ligands for C-C chemokine receptor 4, which is predominantly expressed on T helper 2 lymphocytes, basophils and natural killer cells. We have previously reported that quercetagetin has an inhibitory activity on inflammatory chemokines, which is induced by interferon (IFN)-γ and tumour necrosis factor (TNF)-α, occurring via inhibition of the signal transducer and activator of transcription 1 (STAT1) signal.

OBJECTIVES

To investigate the specific mechanisms of quercetagetin on the STAT1 signal.

METHODS

We confirmed the inhibitory activity of quercetagetin on MDC and STAT1 in HaCaT keratinocytes. The interaction between STAT1 and IFN-γR1 was investigated using immunoprecipitation. The small interfering RNA approach was used to investigate the role of suppressor of cytokine signalling 1 (SOCS1) and transforming growth factor (TGF)-β1 induced by quercetagetin.

RESULTS

Quercetagetin inhibited the expression of MDC at both the protein and mRNA levels in IFN-γ- and TNF-α-stimulated HaCaT human keratinocytes. Moreover, quercetagetin inhibited the phosphorylation of STAT1 through upregulation of SOCS1. Increased expression of SOCS1 disrupted the binding of STAT1 to IFN-γR1. Furthermore, quercetagetin augmented the expression of TGF-β1, which is known to modulate the immune response and inflammation.

CONCLUSIONS

These results suggest that quercetagetin may be a potent inhibitor of the STAT1 signal, which could be a new molecular target for anti-inflammatory treatment, and may thus have therapeutic applications as an immune modulator in inflammatory diseases such as AD.

Genetic variation in the JAK/STAT/SOCS signaling pathway influences breast cancer-specific mortality through interaction with cigarette smoking and use of aspirin/NSAIDs: the Breast Cancer Health Disparities Study

The Janus kinase (JAK)/signal transducer and activator of transcription (STAT) signaling pathway is involved in immune function and cell growth; genetic variation in this pathway could influence breast cancer risk. We examined 12 genes in the JAK/STAT/SOCS signaling pathway with breast cancer risk and mortality in an admixed population of Hispanic (2,111 cases, 2,597 controls) and non-Hispanic white (1,481 cases, 1,585 controls) women. Associations were assessed by Indigenous American (IA) ancestry. After adjustment for multiple comparisons, JAK1 (three of ten SNPs) and JAK2 (4 of 11 SNPs) interacted with body mass index (BMI) among pre-menopausal women, while STAT3 (four of five SNPs) interacted significantly with BMI among post-menopausal women to alter breast cancer risk. STAT6 rs3024979 and TYK2 rs280519 altered breast cancer-specific mortality among all women. Associations with breast cancer-specific mortality differed by IA ancestry; SOCS1 rs193779, STAT3 rs1026916, and STAT4 rs11685878 associations were limited to women with low IA ancestry, and associations with JAK1 rs2780890, rs2254002, and rs310245 and STAT1 rs11887698 were observed among women with high IA ancestry. JAK2 (5 of 11 SNPs), SOCS2 (one of three SNPs), and STAT4 (2 of 20 SNPs) interacted with cigarette smoking status to alter breast cancer-specific mortality. SOCS2 (one of three SNPs) and all STAT3, STAT5A, and STAT5B SNPs significantly interacted with use of aspirin/NSAIDs to alter breast cancer-specific mortality. Genetic variation in the JAK/STAT/SOCS pathway was associated with breast cancer-specific mortality. The proportion of SNPs within a gene that significantly interacted with lifestyle factors lends support for the observed associations.

Macrophage control of phagocytosed mycobacteria is increased by factors secreted by alveolar epithelial cells through nitric oxide independent mechanisms

Tissue-resident macrophages are heterogeneous with tissue-specific and niche-specific functions. Thus, simplified models of macrophage activation do not explain the extent of heterogeneity seen in vivo. We focus here on the respiratory tract and ask whether factors secreted by alveolar epithelial cells (AEC) can influence the functionality of resident pulmonary macrophages (PuM). We have previously reported that factors secreted by AEC increase control of intracellular growth of BCG in macrophages. In the current study, we also aimed to investigate possible mechanisms by which AEC-derived factors increase intracellular control of BCG in both primary murine interstitial macrophages, and bone marrow-derived macrophages and characterize further the effect of these factors on macrophage differentiation. We show that; a) in contrast to other macrophage types, IFN-γ did not increase intracellular growth control of Mycobacterium bovis, Bacillus Calmette-Guérin (BCG) by interstitial pulmonary macrophages although the same macrophages could be activated by factors secreted by AEC; b) the lack of response of pulmonary macrophages to IFN-γ was apparently regulated by suppressor of cytokine signaling (SOCS)1; c) AEC-derived factors did not induce pro-inflammatory pathways induced by IFN-γ e.g. expression of inducible nitric oxide synthase (iNOS), secretion of nitric oxide (NO), or IL-12, d) in contrast to IFN-γ, intracellular bacterial destruction induced by AEC-derived factors was not dependent on iNOS transcription and NO production. Collectively, our data show that PuM were restricted in inflammatory responses mediated by IFN-γ through SOCS1 and that factors secreted by AEC- enhanced the microbicidal capacities of macrophages by iNOS independent mechanisms.

Association of the suppressor of cytokine signaling 1 (SOCS1) gene polymorphisms with acute coronary syndrome in Mexican patients

Recent studies provide evidence on the emerging role of the SOCS1 gene in the development and progression of atherosclerotic lesions. This gene encodes for the suppressor of the cytokine signaling-1 protein that interacts directly with the Janus kinases that are essential intracellular mediators of the immune cytokine action. The aim of this study was to test for associations between SOCS1 gene single nucleotide polymorphisms (SNPs) and the risk of developing acute coronary syndromes (ACS) in a group of Mexicans patients. Four SNPs [-3969 C>T (rs243327), -1656 G>A (rs243330), -820 G>T (rs33977706) and +1125 G>C (rs33932899)] of SOCS1 gene were determined for TaqMan genotyping assays in a group of 447 patients with ACS and 622 healthy controls. Under heterozygous model, the -3969 C>T (rs243327) SNP was associated with increased risk of ACS (OR=1.45, P(Het)=0.021). On the other hand, under co-dominant and heterozygous models, the -1656 G/A (rs243330) SNP was associated with increased risk of ACS (OR=1.47, P(Co-dom)=0.038 and OR=1.50, P(Het)=0.013, respectively). Moreover, under co-dominant, dominant, and heterozygous models, the -820T/G (rs33977706) SNP was associated with increased risk of ACS (OR=1.59, P(Co-dom)=0.03, OR=1.48, P(Dom)=0.028 and OR=1.61, P(Het)=0.01). Finally, under co-dominant and heterozygous models, the +1125 G/C (rs33932899) SNP was associated with increased risk of ACS (OR=1.54, P(Co-dom)=0.006, OR=1.58, P(Het)=0.012, respectively). Models were adjusted for gender, age, body index mass, dyslipidemia, alcohol consumption, and smoking. In summary, our data suggests that the four studied polymorphisms of the SOCS1 gene play an important role as susceptibility markers for developing ACS.

[Triptolide inhibits the inflammatory response of monocytes from rheumatoid arthritis patients by regulating miR-155]

OBJECTIVE

To explore the anti-inflammatory effect of triptolide (TPT) by regulating miR-155 in monocytes pre-stimulated by lipopolysaccharide (LPS) from rheumatoid arthritis (RA) patients.

METHODS

Monocytes were isolated by CD14⁺ magnetic beads from peripheral blood mononuclear cells (PBMCs) of RA and stimulated by LPS for 24 hours. The levels of tumor-necrosis factor-α (TNF-α) and interleukin 6 (IL-6) in monocytes were detected by ELISA and the expression of miR-155 was measured by real-time quantitative PCR (qRT-PCR) in monocytes before and after the treatment of TPT at different concentrations. MiR-155 mimic and negative control were respectively transfected into the LPS-stimulated monocytes by Lipofectamine(TM)2000. Twenty-four hours later, the monocytes were treated with or without TPT for another 24 hours. TNF-α and IL-6 expressions in the cell culture supernatants were detected by ELISA and the expressions of suppressor of cytokine signaling-1 (SOCS1) and Src homology 2 domain-containing inositol 5-phosphatase 1 (SHIP-1) were tested by Western blotting.

RESULTS

TPT suppressed the expressions of TNF-α, IL-6 and miR-155 in LPS-stimulated peripheral blood monocytes from RA patients. Over-expression of miR-155 significantly reversed the down-regulation of TNF-α and IL-6 by TPT in monocytes. TPT up-regulated the expressions of SOCS1 and SHIP-1 in monocytes, but over-expressed miR-155 antagonized the effect of TPT on SHIP-1 while the expression of SOCS1 was not affected.

CONCLUSION

TPT suppressed the expression of miR-155 and up-regulated the release of SHIP-1, thus inhibiting the inflammatory response in the LPS-stimulated monocytes of RA patients.

Conserved inhibitory role of teleost SOCS-1s in IFN signaling pathways

The suppressor of cytokine signaling 1 (SOCS-1) protein is a critical regulator in the immune systems of humans and mammals, which functions classically as an inhibitor of the IFN signaling pathways. However, data on functional characterisation of SOCS-1 in ancient vertebrates are limited. In this study, we report the function of teleost SOCS-1s in IFN signaling in fish models (zebrafish and Tetraodon) and human cells. Structurally, teleost SOCS-1s share conserved functional domains with their mammalian counterparts. Functionally, teleost SOCS-1s could be significantly induced upon stimulation with IFN stimulants and zebrafish IFNφ1. Overexpression of teleost SOCS-1s could dramatically suppress IFNφ1-induced Mx, Viperin and PKZ activation in zebrafish, and IFN-induced ISG15 activation in HeLa cells. Furthermore, a SOCS-1 variant that lacks the KIR domain was also characterised. This study demonstrates the conserved negative regulatory role of teleost SOCS-1s in IFN signaling pathways, providing perspective into the functional conservation of SOCS-1 proteins during evolution.

Pegylated IFN-α regulates hepatic gene expression through transient Jak/STAT activation

The use of pegylated interferon-α (pegIFN-α) has replaced unmodified recombinant IFN-α for the treatment of chronic viral hepatitis. While the superior antiviral efficacy of pegIFN-α is generally attributed to improved pharmacokinetic properties, the pharmacodynamic effects of pegIFN-α in the liver have not been studied. Here, we analyzed pegIFN-α-induced signaling and gene regulation in paired liver biopsies obtained prior to treatment and during the first week following pegIFN-α injection in 18 patients with chronic hepatitis C. Despite sustained high concentrations of pegIFN-α in serum, the Jak/STAT pathway was activated in hepatocytes only on the first day after pegIFN-α administration. Evaluation of liver biopsies revealed that pegIFN-α induces hundreds of genes that can be classified into four clusters based on different temporal expression profiles. In all clusters, gene transcription was mainly driven by IFN-stimulated gene factor 3 (ISGF3). Compared with conventional IFN-α therapy, pegIFN-α induced a broader spectrum of gene expression, including many genes involved in cellular immunity. IFN-induced secondary transcription factors did not result in additional waves of gene expression. Our data indicate that the superior antiviral efficacy of pegIFN-α is not the result of prolonged Jak/STAT pathway activation in hepatocytes, but rather is due to induction of additional genes that are involved in cellular immune responses.

Impact of STAT/SOCS mRNA expression levels after major injury

BACKGROUND

Fulminant changes in cytokine receptor signalling might provoke severe pathological alterations after multiple trauma. The aim of this study was to evaluate the posttraumatic imbalance of the innate immune system with a special focus on the STAT/SOCS family.

METHODS

20 polytraumatized patients were included. Blood samples were drawn 0 h-72 h after trauma; mRNA expression profiles of IL-10, STAT 3, SOCS 1, and SOCS 3 were quantified by qPCR.

RESULTS

IL-10 mRNA expression increased significantly in the early posttraumatic period. STAT 3 mRNA expressions showed a significant maximum at 6 h after trauma. SOCS 1 levels significantly decreased 6 h-72 h after trauma. SOCS 3 levels were significantly higher in nonsurvivors 6 h after trauma.

CONCLUSION

We present a serial, sequential investigation in human neutrophil granulocytes of major trauma patients evaluating mRNA expression profiles of IL-10, STAT 3, SOCS 1, and SOCS 3. Posttraumatically, immune disorder was accompanied by a significant increase of IL-10 and STAT 3 mRNA expression, whereas SOCS 1 mRNA levels decreased after injury. We could demonstrate that death after trauma was associated with higher SOCS 3 mRNA levels already at 6 h after trauma. To support our results, further investigations have to evaluate protein levels of STAT/SOCS family in terms of posttraumatic immune imbalance.

IL-4 suppresses the responses to TLR7 and TLR9 stimulation and increases the permissiveness to retroviral infection of murine conventional dendritic cells

Th2-inducing pathological conditions such as parasitic diseases increase susceptibility to viral infections through yet unclear mechanisms. We have previously reported that IL-4, a pivotal Th2 cytokine, suppresses the response of murine bone-marrow-derived conventional dendritic cells (cDCs) and splenic DCs to Type I interferons (IFNs). Here, we analyzed cDC responses to TLR7 and TLR9 ligands, R848 and CpGs, respectively. We found that IL-4 suppressed the gene expression of IFNβ and IFN-responsive genes (IRGs) upon TLR7 and TLR9 stimulation. IL-4 also inhibited IFN-dependent MHC Class I expression and amplification of IFN signaling pathways triggered upon TLR stimulation, as indicated by the suppression of IRF7 and STAT2. Moreover, IL-4 suppressed TLR7- and TLR9-induced cDC production of pro-inflammatory cytokines such as TNFα, IL-12p70 and IL-6 by inhibiting IFN-dependent and NFκB-dependent responses. IL-4 similarly suppressed TLR responses in splenic DCs. IL-4 inhibition of IRGs and pro-inflammatory cytokine production upon TLR7 and TLR9 stimulation was STAT6-dependent, since DCs from STAT6-KO mice were resistant to the IL-4 suppression. Analysis of SOCS molecules (SOCS1, −2 and −3) showed that IL-4 induces SOCS1 and SOCS2 in a STAT6 dependent manner and suggest that IL-4 suppression could be mediated by SOCS molecules, in particular SOCS2. IL-4 also decreased the IFN response and increased permissiveness to viral infection of cDCs exposed to a HIV-based lentivirus. Our results indicate that IL-4 modulates and counteracts pro-inflammatory stimulation induced by TLR7 and TLR9 and it may negatively affect responses against viruses and intracellular parasites.

Suppressor of cytokine signaling 1 inhibition strategy to enhance anti-HIV vaccination

Extensive efforts aimed at stimulating immune responses by modifying HIV antigens and using various delivery systems and adjuvants have so far failed to generate promising HIV vaccines, highlighting the urgent need to explore alternative immunization approaches. Antigen-presenting cells, such as dendritic cells, play a critical role in the initiation and maintenance of immune responses against HIV infection and dendritic cells are regulated by stimulatory, as well as inhibitory signaling. Recent studies demonstrate that the suppressor of cytokine signaling 1 (SOCS1) functions as an antigen-presentation attenuator by restricting the Janus-activated kinase-signal transducers and activators of transcription and Toll-like receptor-signaling pathways. SOCS1-silenced dendritic cells produce higher levels of both T-helper 1- and 2-polarizing cytokines, broadly enhance memory HIV-specific B-cell and T-cell responses and activate natural killer cells owing to unbridled cytokine feedback signaling loops. Therefore, the inhibition of antigen-presentation attenuators represents a generally applicable and alternative strategy for enhancing the potency of various forms of prophylactic and therapeutic HIV vaccines.

Suppression of interferon lambda signaling by SOCS-1 results in their excessive production during influenza virus infection

Innate cytokine response provides the first line of defense against influenza virus infection. However, excessive production of cytokines appears to be critical in the pathogenesis of influenza virus. Interferon lambdas (IFN-λ) have been shown to be overproduced during influenza virus infection, but the precise pathogenic processes of IFN-λ production have yet to be characterized. In this report, we observed that influenza virus induced robust expression of IFN-λ in alveolar epithelial cells (A549) mainly through a RIG-I-dependent pathway, but IFN-λ-induced phosphorylation of the signal transducer and activator of transcription protein 1 (STAT1) was dramatically inhibited in the infected cells. Remarkably, influenza virus infection induced robust expression of suppressor of cytokine signaling-1 (SOCS-1), leading to inhibition of STAT1 activation. Interestingly, the virus-induced SOCS-1 expression was cytokine-independent at early stage of infection both in vitro and in vivo. Using transgenic mouse model and distinct approaches altering the expression of SOCS-1 or activation of STAT signaling, we demonstrated that disruption of the SOCS-1 expression or expression of constitutively active STAT1 significantly reduced the production of IFN-λ during influenza virus infection. Furthermore, we revealed that disruption of IFN-λ signaling pathway by increased SOCS-1 protein resulted in the activation of NF-κB and thereby enhanced the IFN-λ expression. Together, these data imply that suppression of IFN-λ signaling by virus-induced SOCS-1 causes an adaptive increase in IFN-λ expression by host to protect cells against the viral infection, as a consequence, leading to excessive production of IFN-λ with impaired antiviral response.

Influenza virus infection triggers innate immune responses. However, aberrant host immune responses such as excessive production of cytokines contribute to the pathogenesis of influenza virus. Type III interferons (IFN-λ) constitute the major innate immune response to influenza virus infection, but the precise pathogenic processes of IFN-λ production and mechanistic underpinnings are not well understood. In this study, we report that influenza virus induces robust IFN-λ expression mainly through a RIG-I-dependent pathway, but signaling activated by IFN-λ was dramatically inhibited by virus-induced SOCS-1. Importantly, we found that disruption of the SOCS-1 expression or forced activation of STAT1 significantly reduced the expression of IFN-λ in vitro and in vivo, suggesting that suppression of IFN-λ signaling by SOCS-1 results in their excessive production during influenza virus infection. Furthermore, our experiments revealed that disruption of IFN-λ signaling pathway resulted in the activation of NF-κB that governs the IFN-λ expression. Together these findings, we propose that impaired antiviral response of IFN-λ due to the inhibitory effect of SOCS-1 causes an adaptive increase in IFN-λ expression by host to protect cells against the viral infection. This is a novel mechanism that may be critical in the pathogenesis of the influenza virus strains that induce hypercytokinemia.

Expression of suppressor of cytokine signaling 1 in the peripheral blood of patients with idiopathic pulmonary fibrosis

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a progressive diffuse parenchymal disease with a poor prognosis. A variety of cytokines and chemokines are involved in its pathophysiology. The aim of this study was to evaluate the clinical features in IPF patients with the expression of suppressor of cytokine signaling 1 (SOCS-1), which acts as a negative regulator of cytokine signaling.

METHODS

IPF patients (n = 20) and healthy controls (n = 16) were included in this study. The expression of SOCS-1 was analyzed in peripheral blood mononuclear cells (PBMC) of subjects using RT-PCR. Interleukin 4 (IL-4), transforming growth factor β1 (TGF-β1) and type I collagen expression were also analyzed in each individual using enzyme-linked immunosorbent assay (ELISA). The clinical characteristics of IPF patients were delineated. These results were analyzed by SPSS13.0 statistics software.

RESULTS

SOCS-1 mRNA expression was significantly decreased in the PBMC of IPF patients compared with healthy controls; serum levels of IL-4 and TGF-β1 were higher in IPF patients. The patients with lower expression of SOCS-1 developed lower percentage of forced vital capacity (FVC%) and DLCO/VA. A patients' SOCS-1 mRNA level was negatively correlated with serum levels of IL-4, and negatively correlated with their high-resolution computed tomography (HRCT) scores.

CONCLUSIONS

SOCS-1 mRNA can be detected in PBMC, and it is down-regulated in IPF patients. The expression of SOCS-1 is associated with the severity of IPF patients' symptoms, so it might be the predictor of disease severity. SOCS-1 might play an important role in IPF by reducing the expression of the T helper type 2 (Th2) cell-related cytokine IL-4.

Upregulation of SOCS-1 by Nutlin-3 in acute myeloid leukemia cells but not in primary normal cells

OBJECTIVE

It has been shown that SOCS-1 plays an important role in the proper control of cytokine/growth factor responses and acts as a tumor suppressor in acute myeloid leukemias. Therefore, the objective of the present study was to evaluate the in vitro effect of treatment with Nutlin-3, a small molecule inhibitor of the MDM2/p53 interaction, on the expression of the suppressor of cytokine signaling 1 in primary acute myeloid leukemia cells and in myeloid cell lines with differential p53 status.

METHOD

The expression of the suppressor of cytokine signaling 1 was quantitatively analyzed by real-time PCR in myeloid p53wild-type (OCI and MOLM) and p53null HL-60, leukemic cell lines, in patient-derived acute myeloid leukemia blasts, and in primary normal cell types, such as macrophages, endothelial cells, and bone marrow mesenchymal stem cells. The p53-dependence of the suppressor of cytokine signaling 1 upregulation that is induced by Nutlin-3 was analyzed in experiments performed using siRNA for p53, while the functional upregulation of the suppressor of cytokine signaling 1 was analyzed by assessing the levels of phosphorylated STAT-3.

RESULTS

Nutlin-3 significantly upregulated the transcription of the suppressor of cytokine signaling 1 in p53wild-type OCI and MOLM but not in p53deleted p53null HL60, myeloid leukemic cell lines, as well as in primary acute myeloid leukemia blasts. Conversely, and somewhat unexpectedly, Nutlin-3 did not modulate the suppressor of cytokine signaling 1 expression in primary normal macrophages, endothelial cells, and bone marrow mesenchymal stem cells. The p53-dependent upregulation of the suppressor of cytokine signaling 1 by Nutlin-3 was associated with the downregulation of phosphorylated STAT-3, a major molecular target of the suppressor of cytokine signaling 1.

CONCLUSION

Overall, our data suggest a potential role for the suppressor of cytokine signaling 1 as a therapeutic target of Nutlin-3 in p53 wild-type acute myeloid leukemias.