Suppressor of cytokine signaling 3 A+930-->G (rs4969168) polymorphism is associated with apolipoprotein A1 and low-density lipoprotein cholesterol

This study aimed to detect the association of the suppressor of cytokine signaling 3 gene (SOCS3) A+930-->G (rs4969168) single nucleotide polymorphism (SNP) and environmental factors with serum lipid levels in the Han and Mulao populations. Genotyping of the SOCS3 A+930-->G (rs4969168) SNP was performed in 752 of Han and 690 of Mulao participants using polymerase chain reaction and restriction fragment length polymorphism. The genotype and allele frequencies were significantly different between the Han and Mulao populations (GG, 57.71% vs. 51.16%, GA, 36.97% vs. 41.16%, AA, 5.32% vs. 7.68%, P = 0.023; G, 76.20% vs. 71.74%, A, 23.80% vs. 28.26%; P = 0.006; respectively). Serum apolipoprotein (Apo) A1 levels in Han were different among the genotypes (P < 0.05). Subgroup analyses showed that the levels of ApoA1 in Han females, and ApoA1 and low-density lipoprotein cholesterol (LDL-C) in Mulao males were different among the genotypes (P < 0.05). Serum lipid parameters were also associated with several environmental factors in both ethnic groups (P < 0.05-0.001). These findings suggest that there may be a racial/ethnic- and/or sex-specific association between the SOCS3 A+930-->G (rs4969168) SNP and serum lipid parameters in some populations.

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.

Sodium salicylate reduced insulin resistance in the retina of a type 2 diabetic rat model

Sodium salicylate has been reported to reduce markers of diabetic retinopathy in a type 1 rat model. Because rates of type 2 diabetes are on the rise, we wanted to determine whether salicylate could improve insulin resistance in a type 2 rat model, as well as improve retinal function. We treated lean and obese BBZDR/Wor type 2 diabetic rats with salicylate in their chow for 2 months. Prior to salicylate treatment, rats underwent an electroretinogram to measure retinal function. After 2 months of treatment, rats underwent an additional electroretinogram prior to sacrifice. In addition to the animal model, we also treated retinal endothelial cells (REC) and rat Müller cells with salicylate and performed the same analyses as done for the rat retinal lysates. To investigate the role of salicylate in insulin signaling, we measured TNFα and caspase 3 levels by ELISA, as well as performed Western blotting for insulin receptor substrate 1, insulin receptor, SOCS3, and pro- and anti-apoptotic markers. Data demonstrated that salicylate significantly improved retinal function, as well as reduced TNFα and SOCS3-induced insulin resistance in all samples. Overall, results suggest that salicylate is effective in reducing insulin resistance in the retina of type 2 diabetic rat models.

Phosphodiesterase-3B-cAMP pathway of leptin signalling in the hypothalamus is impaired during the development of diet-induced obesity in FVB/N mice

The phosphodiesterase-3B (PDE3B)-cAMP pathway plays an important role in transducing the action of leptin in the hypothalamus. Obesity is usually associated with hyperleptinaemia and resistance to anorectic and body weight-reducing effects of leptin. To determine whether the hypothalamic PDE3B-cAMP pathway of leptin signalling is impaired during the development of diet-induced obesity (DIO), we fed male FVB/N mice a high-fat diet (HFD: 58% kcal as fat) or low-fat diet (LFD: 6% kcal as fat) for 4 weeks. HFD fed mice developed DIO in association with hyperphagia, hyperleptinaemia and hyperinsulinaemia. Leptin (i.p.) significantly increased hypothalamic PDE3B activity and phosphorylated (p)-Akt levels in LFD-fed but not in HFD-fed mice. However, basal p-Akt levels in hypothalamus were increased in DIO mice. Additionally, amongst six-microdissected brain nuclei examined, leptin selectively decreased cAMP levels in the arcuate nucleus (ARC) of LFD-fed mice but failed to do so in HFD-fed mice. We next tested whether both the PBE3B and Akt pathways of leptin signalling remained impaired in DIO mice on the HFD for 12 weeks (long-term). DIO mice were hyperinsulinaemic and hyperleptinaemic in association with impaired glucose and insulin tolerance. Although, in LFD-fed mice, leptin significantly increased PDE3B activity and p-Akt levels in the hypothalamus, it failed to do so in HFD-fed mice. Also, basal p-Akt levels in the hypothalamus were increased in DIO mice and leptin had no further effect. Similarly, immunocytochemistry showed that leptin increased the number of p-Akt-positive cells in the ARC of LFD-fed but not in HFD-fed mice, and there was an increased basal number of p-Akt positive cells in the ARC of DIO mice. These results suggest that the PDE3B-cAMP- and Akt-pathways of leptin signalling in the hypothalamus are impaired during the development of DIO. Thus, a defect in the regulation by leptin of the hypothalamic PDE3B-cAMP pathway and Akt signalling may be one of the mechanisms of central leptin resistance and the development of DIO.

SOCS3 silencing attenuates eosinophil functions in asthma patients

Eosinophils are one of the key inflammatory cells in asthma. Eosinophils can exert a wide variety of actions through expression and secretion of multiple molecules. Previously, we have demonstrated that eosinophils purified from peripheral blood from asthma patients express high levels of suppressor of cytokine signaling 3 (SOCS3). In this article, SOCS3 gene silencing in eosinophils from asthmatics has been carried out to achieve a better understanding of the suppressor function in eosinophils. SOCS3 siRNA treatment drastically reduced SOCS3 expression in eosinophils, leading to an inhibition of the regulatory transcription factors GATA-3 and FoxP3, also interleukin (IL)-10; in turn, an increased STAT3 phosphorilation was observed. Moreover, SOCS3 abrogation in eosinophils produced impaired migration, adhesion and degranulation. Therefore, SOCS3 might be regarded as an important regulator implicated in eosinophil mobilization from the bone marrow to the lungs during the asthmatic process.

Down-regulation of suppressor of cytokine signaling 3 by miR-122 enhances interferon-mediated suppression of hepatitis B virus

MicroRNA-122 (miR-122) is involved in the pathogenesis of several liver diseases, including chronic hepatitis B infection and hepatocellular carcinoma. This study aimed to explore the potential role of miR-122 in the interferon (IFN)-mediated suppression of hepatitis B virus (HBV) in hepatocytes. We found that elevated expression of suppressor of cytokine signaling 3 (SOCS3) following HBV infection, contributed to the inactivation of the IFN signaling pathway. Based on previous studies from our laboratory showing that miR-122 can modulate type I IFN expression by inhibiting SOCS1 expression, we analyzed the SOCS3 mRNA sequence for putative miR-122 binding sites. We demonstrate that miR-122 inhibits SOCS3 expression by targeting the 3'-untranslated region of the SOCS3 mRNA within the region 1887-1910 nucleotides. Finally, we demonstrate that significantly increased levels of IFN lead to decreased HBV expression in miR-122 mimic-treated Huh7 cells, whereas inhibition of endogenous miR-122 leads to enhanced viral production, owing to a marked decrease in IFN expression. Taken together, our results demonstrate that miR-122 down-regulates SOCS3, thus positively affecting the anti-HBV efficiency of endogenous type I IFN. Our study suggests that suppression of miR-122 induced by HBV infection, leads to the inactivation of IFN expression, which in turn enhances HBV replication, contributing to viral persistence and hepatocarcinogenesis.

IL-1 signaling modulates activation of STAT transcription factors to antagonize retinoic acid signaling and control the TH17 cell-iTreg cell balance

Interleukin 17 (IL-17)-producing helper T cells (TH17 cells) and CD4(+) inducible regulatory T cells (iTreg cells) emerge from an overlapping developmental program. In the intestines, the vitamin A metabolite retinoic acid (RA) is produced at steady state and acts as an important cofactor to induce iTreg cell development while potently inhibiting TH17 cell development. Here we found that IL-1 was needed to fully override RA-mediated expression of the transcription factor Foxp3 and induce protective TH17 cell responses. By repressing expression of the negative regulator SOCS3 dependent on the transcription factor NF-κB, IL-1 increased the amplitude and duration of phosphorylation of the transcription factor STAT3 induced by TH17-polarizing cytokines, which led to an altered balance in the binding of STAT3 and STAT5 to shared consensus sequences in developing T cells. Thus, IL-1 signaling modulated STAT activation downstream of cytokine receptors differently to control the TH17 cell-iTreg cell developmental fate.

MicroRNA-185 targets SOCS3 to inhibit beta-cell dysfunction in diabetes

Diabetes is the most common and complex metabolic disorder, and one of the most important health threats now. MicroRNAs (miRNAs) are a group of small non-coding RNAs that have been suggested to play a vital role in a variety of physiological processes, including glucose homeostasis. In this study, we investigated the role of miR-185 in diabetes. MiR-185 was significantly downregulated in diabetic patients and mice, and the low level was correlated to blood glucose concentration. Overexpression of miR-185 enhanced insulin secretion of pancreatic β-cells, promoted cell proliferation and protected cells from apoptosis. Further experiments using in silico prediction, luciferase reporter assay and western blot assay demonstrated that miR-185 directly targeted SOCS3 by binding to its 3'-UTR. On the contrary to miR-185's protective effects, SOCS3 significantly suppressed functions of β-cell and inactivated Stat3 pathway. When treating cells with miR-185 mimics in combination with SOCS3 overexpression plasmid, the inhibitory effects of SOCS3 were reversed. While combined treatment of miR-185 mimics and SOCS3 siRNA induced synergistically promotive effects compared to either miR-185 mimics or SOCS3 siRNA treatment alone. Moreover, we observed that miR-185 level was inversely correlated with SOCS3 expression in diabetes patients. In conclusion, this study revealed a functional and mechanistic link between miR-185 and SOCS3 in the pathogenesis of diabetes. MiR-185 plays an important role in the regulation of insulin secretion and β-cell growth in diabetes. Restoration of miR-185 expression may serve a potentially promising and efficient therapeutic approach for diabetes.

High suppressor of cytokine signaling-3 expression impairs STAT3-dependent protective effects of interleukin-22 in ulcerative colitis in remission

BACKGROUND

High SOCS3 expression in intestinal epithelial cells (IECs) of patients with ulcerative colitis (UC) in remission reflects the shorter time to relapse. We investigated whether high SOCS3 increased risk for relapse through violating STAT3-dependent protective effects of interleukin (IL)-22 during UC remission.

METHODS

Expression of IL-22 and c-Myc in UC remission mucosa was analyzed by immunohistochemistry. Effects of IL-22 on migration and proliferation of IEC cell lines with enforced SOCS3 expression were assessed with wounding assay and CCK-8 assay, respectively. Influence of STAT3 interference and SOCS3 overexpression on IL-22-regulated expression of antimicrobial peptide and proliferation-related molecules, including DMBT1, c-Myc, Survivin, Bcl-2, and Bcl-xL, were performed with quantitative real-time polymerase chain reaction or Western blot.

RESULTS

Patients with UC in remission showed significantly more IL-22-positive immune cells, but no difference of epithelial c-Myc levels, in mucosa compared with healthy controls. Overexpression of SOCS3 nearly abolished IL-22-induced activation of STAT3. By inhibiting STAT3 signaling, SOCS3 influenced IL-22-induced expression of DMBT1, c-Myc, Survivin, and Bcl-2 as well as proliferation and migration processes in cultured IEC cell line.

CONCLUSIONS

SOCS3 overexpression impairs IL-22-mediated epithelial homeostasis and mucosal wound healing, which could be the mechanism for high SOCS3 IEC expression contributed early relapse of mucosal inflammation. Prevention of SOCS3 expression or enhancement of IL-22/STAT3 signaling in IEC seems to be rational therapeutic strategies for UC remission maintenance.

[Serum levels of suppressor of cytokine signaling 3, tumor necrosis factor-alpha and interleukin-10 in preeclampsia mothers and their clinical values]

OBJECTIVE

To explore the serum levels of suppressor of cytokine signaling 3 (SOCS3), tumor necrosis factor-alpha (TNF-α) and interleukin-10 (IL-10) in preeclampsia mothers and determine their clinical values.

METHODS

A total of 40 preeclampsia mothers at International Peace Maternity and Child Health Hospital of China Welfare Institute Affiliated to Shanghai Jiaotong University from March 2011 to August 2013 were enrolled into observation group. Another 40 cases of mothers without pregnancy complications were selected as control group. Then the serum contents of SOCS3, TNF-α and IL-10 were detected and their correlations analyzed.

RESULTS

(1) The mRNA levels of SOCS3 of observation and control groups were 38 ± 6and 100 ± 16while the mRNA levels of TNF-α 226 ± 40 and 100 ± 19 respectively; (2)the proteins levels of SOCS3 of observation group were lower than those of control group (P < 0.05) while the proteins levels of TNF-α of observation group were higher than those of control group (P < 0.05); (3)the mRNA and protein contents of SOCS3 were negatively correlated with mRNA and protein contents of TNF-α and positively correlated with IL-10.

CONCLUSION

The serum content of SOCS3 decreases significantly in preeclampsia so that there is a down-regulation of Th1 type cytokine TNF-α and an up-regulation of Th2 type cytokine IL-10. And it may play an important role in the occurrence of disease.

Hepatitis C virus infection in vitro triggers endoplasmic reticulum stress and downregulates insulin receptor substrates 1 and 2 through upregulation of cytokine signaling suppressor 3

Hepatitis C virus (HCV) infection is highly prevalent worldwide and most of HCV infections enter into chronic phase subsequently leading to insulin resistance (IR) and clinical complications. Although the clinics of chronic HCV infection is well described, there is need to better understand the molecular mechanisms of HCV-induced IR. Therefore this study was aimed to unveil the role of host genes involved in the development of HCV-induced IR. For this purpose the expression of selected genes in HCV-infected and non-infected Huh-7 cells at various time post infection (p.i.) was assayed by real-time PCR. HCV infection was found to trigger endoplasmic reticulum (ER) stress response as demonstrated by an increase in the expression of calreticulin (Cal) gene but no change in the expression of Gadd153 gene. The infection also enhanced the expression of suppressor of cytokine signaling 3 (SOCS-3), responsible for the degradation of insulin receptor substrates (IRS). Moreover, it led to a decreased expression of key signaling molecules IRS-1 and IRS-2, unchanged expression of SOCS-7 and increased expression of downstream signaling molecule Akt. Altogether these findings indicate that the HCV infection induces ER stress and IR in Huh-7 cells in vitro.

Japanese encephalitis virus upregulates the expression of SOCS3 in mouse brain and Raw264.7 Cells

Japanese encephalitis virus (JEV) is one of the pathogens that can invade the central nervous system, causing acute infection and inflammation of brain. SOCS3 protein plays a vital role in immune processes and inflammation of the central nervous system. In this study, Raw264.7 cells and suckling mice were infected with JEV, and SOCS3 expression was analyzed by the gene expression profile, semiquantitative RT-PCR, qRT-PCR, immunohistochemistry (IHC) and Western blot. Results indicated that 520 genes were found to be differentially expressed (fold change ≥ 2.0, p < 0.05) in total. The differentially regulated genes were involved in biological processes, such as stimulus response, biological regulation and immune system processes. JEV early infection could induce SOCS3 expression, upregulating both the mRNA and protein levels in Raw264.7 cells in a time-dependent manner. The SOCS3 expression was much lower in Raw264.7 cells infected with inactivated JEV than wild-type JEV. In vivo, SOCS3 protein was also found to upregulate the expression of mRNA and protein in JEV-infected mouse brain. Taken together, our data showed that JEV early infection could induce the upregulation of SOCS3 expression, both in vitro and in vivo, providing the basic theoretical foundation for future research on the invasion mechanism of JEV.

Impaired interferon signaling in chronic hepatitis C patients with advanced fibrosis via the transforming growth factor beta signaling pathway

Malnutrition in the advanced fibrosis stage of chronic hepatitis C (CH-C) impairs interferon (IFN) signaling by inhibiting mammalian target of rapamycin complex 1 (mTORC1) signaling. However, the effect of profibrotic signaling on IFN signaling is not known. Here, the effect of transforming growth factor (TGF)-β signaling on IFN signaling and hepatitis C virus (HCV) replication was examined in Huh-7.5 cells by evaluating the expression of forkhead box O3A (Foxo3a), suppressor of cytokine signaling 3 (Socs3), c-Jun, activating transcription factor 2, ras homolog enriched in brain, and mTORC1. The findings were confirmed in liver tissue samples obtained from 91 patients who received pegylated-IFN and ribavirin combination therapy. TGF-β signaling was significantly up-regulated in the advanced fibrosis stage of CH-C. A significant positive correlation was observed between the expression of TGF-β2 and mothers against decapentaplegic homolog 2 (Smad2), Smad2 and Foxo3a, and Foxo3a and Socs3 in the liver of CH-C patients. In Huh-7.5 cells, TGF-β1 activated the Foxo3a promoter through an AP1 binding site; the transcription factor c-Jun was involved in this activation. Foxo3a activated the Socs3 promoter and increased HCV replication. TGF-β1 also inhibited mTORC1 and IFN signaling. Interestingly, c-Jun and TGF-β signaling was up-regulated in treatment-resistant IL28B minor genotype patients (TG/GG at rs8099917), especially in the early fibrosis stage. Branched chain amino acids or a TGF-β receptor inhibitor canceled these effects and showed an additive effect on the anti-HCV activity of direct-acting antiviral drugs (DAAs).

CONCLUSION

Blocking TGF-β signaling could potentiate the antiviral efficacy of IFN- and/ or DAA-based treatment regimens and would be useful for the treatment of difficult-to-cure CH-C patients.

Inhibition of leptin-induced vascular extracellular matrix remodelling by adiponectin

Vascular extracellular matrix (ECM) remodelling, which is the result of disruption in the balance of ECM synthesis and degradation, induces vessel fibrosis and thereby leads to hypertension. Leptin is known to promote tissue fibrosis, while adiponectin has recently been demonstrated to be anti-fibrogenic in tissue fibrosis. In this study, we aimed to evaluate the leptin-antagonist function of adiponectin and to further elucidate the mechanisms through which adiponectin dampens leptin signalling in vascular smooth muscle cells, thus preventing excess ECM production, in our already established 3D co-culture vessel models. Our 3D co-culture vessel model, which mimics true blood vessels, is composed of vascular endothelial cells, vascular smooth muscle cells and collagen type I. We validated the profibrogenic effects of leptin and analysed matrix metalloproteinase 2 (MMP2), MMP9, tissue inhibitor of metalloproteinase 1 (TIMP1) and collagen types II/IV secretion in 3D vessel models. The protective/inhibitory effects of adiponectin were re-analysed by inhibiting adiponectin receptor 1 (AdipoR) and AdipoR2 expression in endothelial cells using RNAi technology. In the 3D vessel models, adiponectin blocked the leptin-stimulated secretion of collagen types II/IV and TIMP1 while significantly increasing MMP2/9 activity. In endothelial cells, adiponectin induced phosphorylation of AMPK, thereby suppressing leptin-mediated STAT3 phosphorylation through induction of SOCS3 in smooth muscle cells. Our findings indicate that adiponectin disrupted the leptin-induced vascular ECM remodelling via AdipoR1 and enhanced AMPK signalling in endothelial cells, which, in turn, promoted SOCS3 up-regulation in smooth muscle cells to repress leptin-stimulated phosphorylation of STAT3.

Ghrelin induces leptin resistance by activation of suppressor of cytokine signaling 3 expression in male rats: implications in satiety regulation

The anorexigenic adipocyte-derived hormone leptin and the orexigenic hormone ghrelin act in opposition to regulate feeding behavior via the vagal afferent pathways. The mechanisms by which ghrelin exerts its inhibitory effects on leptin are unknown. We hypothesized that ghrelin activates the exchange protein activated by cAMP (Epac), inducing increased SOCS3 expression, which negatively affects leptin signal transduction and neuronal firing in nodose ganglia (NG) neurons. We showed that 91 ± 3% of leptin receptor (LRb) -bearing neurons contained ghrelin receptors (GHS-R1a) and that ghrelin significantly inhibited leptin-stimulated STAT3 phosphorylation in rat NG neurons. Studies of the signaling cascades used by ghrelin showed that ghrelin caused a significant increase in Epac and suppressor of cytokine signaling 3 (SOCS3) expression in cultured rat NG neurons. Transient transfection of cultured NG neurons to silence SOCS3 and Epac genes reversed the inhibitory effects of ghrelin on leptin-stimulated STAT3 phosphorylation. Patch-clamp studies and recordings of single neuronal discharges of vagal primary afferent neurons showed that ghrelin markedly inhibited leptin-stimulated neuronal firing, an action abolished by silencing SOCS3 expression in NG. Plasma ghrelin levels increased significantly during fasting. This was accompanied by enhanced SOCS3 expression in the NG and prevented by treatment with a ghrelin antagonist. Feeding studies showed that silencing SOCS3 expression in the NG reduced food intake evoked by endogenous leptin. We conclude that ghrelin exerts its inhibitory effects on leptin-stimulated neuronal firing by increasing SOCS3 expression. The SOCS3 signaling pathway plays a pivotal role in ghrelin's inhibitory effect on STAT3 phosphorylation, neuronal firing, and feeding behavior.

Dysregulation of the suppressor of cytokine signalling 3-signal transducer and activator of transcription-3 pathway in the aetiopathogenesis of Sjögren's syndrome

The suppressor of cytokine signalling 3 (SOCS3) negatively regulates the Janus kinase (JAK)/signal transducer and activator of transcription-3 (STAT-3)/interleukin (IL)-17 pathway. The proinflammatory cytokine IL-17 is over-expressed in Sjögren's syndrome (SS) and is a key factor in its pathogenesis. We hypothesized that IL-17 over-expression in SS results from ineffective regulation by SOCS3. The expression of SOCS3 was analysed in peripheral blood mononuclear cells (PBMC) from SS cases, sicca controls (SC) and healthy controls (HC) and tissue samples from SS, SC and healthy salivary glands (HSG). PBMC and salivary gland tissue from SS and controls were dual-immunostained for SOCS3 and IL-17. IL-6-stimulated PBMC from SS and controls were evaluated for time-dependent STAT-3 activation and SOCS3 induction, and for IL-17 expression. Immunoblotting revealed greater levels of SOCS3 in PBMC from SS than SC (P = 0·017) or HC (P < 0·001). Similarly, the proportion of salivary-gland tissue cells staining for SOCS3 was significantly higher in SS than SC (P = 0·029) or HSG (P = 0·021). The cells in PBMC/salivary gland samples from controls predominantly expressed either SOCS3 or IL-17. However, there was a high frequency of SOCS3/IL-17 co-expression within cells of SS samples. IL-6-stimulation of PBMC from SS cases revealed prolonged activation of STAT-3 with reduced negative regulation by SOCS3, and enhanced expression of IL-17. This study showed that SOCS3 expression is up-regulated in SS. However, the absence in SS of the normal inverse relationship between SOCS3 and pSTAT-3/IL-17 indicates a functional disturbance in this signalling cascade. Consequently, a reduction in function, rather than a reduction in expression of SOCS3 accounts for the unregulated expression of IL-17 in SS, and may play a crucial role in aetiopathogenesis.

[Activation of TNF-α and signaling pathway in the hypothalamus of the rats subjected to chronic unpredictable mild stressors after middle cerebral artery occlusion]

This study was aimed to investigate the changes of the hypothalamic-pituitary-adrenal axis (HPAA) activity and the cytokines system in the hypothalamus of the depressive rats which were exposed to chronic unpredictable mild stressors (CUMS) after middle cerebral artery occlusion (MCAO). By means of qRT-PCR, ELISA and Western blot, mRNA and/or protein expressions of corticotropin releasing factor (CRF), tumor necrosis factors-α (TNF-α), suppressor of cytokines signaling 3 (SOCS3), phosphorylation of signal transducers and activators of transcription 3 (pSTAT3) were measured in the hypothalamus of rats. The results showed that, compared with control group, CUMS+MCAO group exhibited increased mRNA levels of CRF, TNF-α, SOCS3, as well as up-regulated CRF, TNF-α, SOCS3 and pSTAT3 protein expressions. Furthermore, there were correlations between CRF and TNF-α, TNF-α and SOCS3, SOCS3 and pSTAT3, respectively. These observations indicated the CRF system was activated in the post stroke depression (PSD) status. The TNF-α and its signaling pathway, STAT3/SOCS3, were up-regulated in mRNA and protein levels. In conclusion, this study presents the evidence which supports the hypothesis of signaling cross-talk between the CRF system and TNF-α signaling pathway after ischemic stroke and CUMS.

Insulin resistance, adipokine profile and hepatic expression of SOCS-3 gene in chronic hepatitis C

AIM

To analyze adipokine concentrations, insulin resistance and hepatic expression of suppressor of cytokine signaling 3 (SOCS-3) in patients with chronic hepatitis C genotype 1 with normal body weight, glucose and lipid profile.

METHODS

The study group consisted of 31 patients with chronic hepatitis C and 9 healthy subjects. Total levels of adiponectin, leptin, resistin, visfatin, omentin, osteopontin and insulin were measured using an ELISA kit. The hepatic expression of SOCS-3 was determined by the use of the reverse transcription polymerase chain reaction method.

RESULTS

Homeostasis model assessment for insulin resistance (HOMA-IR) values were significantly higher in hepatitis C virus (HCV) infected patients without metabolic disorders compared to healthy controls (2.24 vs 0.59, P = 0.0003). Hepatic steatosis was observed in 32.2% of patients with HCV infection and was found in patients with increased HOMA-IR index (2.81 vs 1.99, P = 0.05) and reduced adiponectin level (5.96 vs 8.37, P = 0.04). Inflammatory activity (G ≥ 2) was related to increased osteopontin concentration (34.04 vs 23.35, P = 0.03). Advanced liver fibrosis (S ≥ 2) was associated with increased levels of omentin and osteopontin (436.94 vs 360.09, P = 0.03 and 32.84 vs 20.29, P = 0.03) and reduced resistin concentration (1.40 vs 1.74, P = 0.047). No correlations were reported between adipokine profile, HOMA-IR values and hepatic expression of the SOCS-3 gene.

CONCLUSION

We speculated that no relationship between adipokines and HOMA-IR values may indicate that HCV can induce insulin resistance itself. Some adipokines appear to be biochemical markers of steatosis, inflammation and fibrosis in patients with chronic HCV infection. © 2014 Baishideng Publishing Group Inc. All rights reserved.

Short communication: serum-based assay accurately detects single nucleotide polymorphisms of IL28B and SOCS3 in HIV/hepatitis C virus-coinfected subjects

Single nucleotide polymorphisms (SNPs) have become important in predicting treatment response to interferon containing anti-hepatitis C virus (HCV) therapy in HCV and HIV/HCV-infected patients. A reliable method for extracting host DNA from serum for genotyping assays would present a practical alternative for clinicians and investigators seeking to perform SNP analyses in HCV-infected patients, particularly in resource-limited settings. Human genomic DNA was extracted from peripheral blood mononuclear cells (PBMCs) and serum of 51 HIV/HCV coinfected patients using the QIAamp DNA Blood Mini Kit and QIAamp Min Elute Virus Spin Kit, respectively. Genotyping assays for the IL28B SNP (rs12979860) and SOCS3 SNP (rs4969170) were performed using the commercially available ABI Taqman allelic discrimination kit and reverse transcriptase-polymerase chain reaction (RT-PCR) was performed using 50 cycles. Results of the genotyping assays using DNA from both PBMCs and cell-free serum were determined separately and then analyzed for concurrence. Genotype analyses performed using DNA isolated from PBMCs or cell-free serum showed a 100% agreement between the IL28B genotyping results from the serum and PBMC isolates and 98% agreement for SOCS3 SNP. This novel serum-based assay to isolate DNA fragments from the serum of HIV/HCV-coinfected subjects can accurately determine a subject's genotype for IL28B (rs12979860) and SOCS3 (rs4969170). This assay could be immediately valuable for detecting clinically relevant SNPs from serum in cases in which PBMCs are not available.

Inducible STAT3 NH2 terminal mono-ubiquitination promotes BRD4 complex formation to regulate apoptosis

Signal Transducers and Activator of Transcription-3 (STAT3) are latent transcription factors that are regulated by post-translational modifications (PTMs) in response to cellular activation by the IL-6 superfamily of cytokines to regulate cell cycle progression and/or apoptosis. Here we observe that STAT3 is inducibly mono-ubiquitinated and investigate its consequences. Using domain mapping and highly specific selected reaction monitoring-mass spectrometric assays, we identify lysine (K) 97 in its NH2-terminal domain as the major mono-ubiquitin conjugation site. We constructed a mono-ubiquitinated mimic consisting of a deubiquitinase-resistant monomeric ubiquitin fused to the NH2 terminus of STAT3 (ubiquitinated-STAT3 FP). In complex assays of ectopically expressed ubi-STAT3-FP, we observed enhanced complex formation with bromodomain-containing protein 4 (BRD4), a component of the activated positive transcriptional elongation factor (P-TEFb) complex. Chromatin immunoprecipitation experiments in STAT3(+/-) and STAT3(-/-) MEFs showed BRD4 recruitment to STAT3-dependent suppressor of cytokine signaling-3 gene (SOCS3). The effect of a selective small molecule inhibitor of BRD4, JQ1, to inhibit SOCS3 expression demonstrated the functional role of BRD4 for STAT3-dependent transcription. Additionally, ectopic ubiquitinated-STAT3 FP expression upregulated BCL2, BCL2L1, APEX1, SOD2, CCND1 and MYC expression indicating the role of ubiquitinated STAT3 in anti-apoptosis and cellular proliferation. Finally we observed that ubiquitinated-STAT3 FP suppressed TNFα-induced apoptotic cell death, indicating the functional importance of mono-ubiquitinated STAT3 in antiapoptotic gene expression. We conclude that STAT3 mono-ubiquitination is a key trigger in BRD4-dependent antiapoptotic and pro-proliferative gene expression programs. Thus, inhibiting the STAT3 mono-ubiquitination-BRD4 pathway may be a novel therapeutic target for the treatment of STAT3-dependent proliferative diseases.

SOCS3 expression correlates with severity of inflammation in mouse hepatitis virus strain 3-induced acute liver failure and HBV-ACLF

Recently, suppressor of cytokine signaling-3 (SOCS3) has been shown to be an inducible endogenous negative regulator of Janus kinase/signal transducers and activators of transcription (JAK/STAT) pathway which is relevant in inflammatory response, while its functions in acute liver failure and HBV-induced acute-on-chronic liver failure (HBV-ACLF) have not been fully elucidated. In this study, we explored the role of SOCS3 in the development of mouse hepatitis virus strain 3 (MHV-3)-induced acute liver failure and its expression in liver and peripheral blood mononuclear cells (PBMCs) of patients with HBV-ACLF. Inflammation-related gene expression was detected by real-time PCR, immunohistochemistry and Western blotting. The correlation between SOCS3 level and liver injury was studied. Our results showed that the SOCS3 expression was significantly elevated in both the liver tissue and PBMCs from patients with HBV-ACLF compared to mild chronic hepatitis B (CHB). Moreover, a time course study showed that SOCS3 level was increased remarkably in the liver of BALB/cJ mice at 72 h post-infection. Pro-inflammatory cytokines, interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α, were also increased significantly at 72 h post-infection. There was a close correlation between hepatic SOCS3 level and IL-6, and the severity of liver injury defined by alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels, respectively. These data suggested that SOCS3 may play a pivotal role in the pathogenesis of MHV-3-induced acute liver failure and HBV-ACLF.

Zac1 regulates astroglial differentiation of neural stem cells through Socs3

Cell-fate decisions and differentiation of embryonic and adult neural stem cells (NSC) are tightly controlled by lineage-restricted and temporal factors that interact with cell-intrinsic programs and extracellular signals through multiple regulatory loops. Imprinted genes are important players in neurodevelopment and mental health although their molecular and cellular functions remain poorly understood. Here, we show that the paternally expressed transcriptional regulator Zac1 (zinc finger protein regulating apoptosis and cell cycle arrest) is transiently induced during astroglial and neuronal differentiation of embryonic and adult NSC lines. Thereby, Zac1 transactivates Socs3 (suppressor of cytokine signaling 3), a potent inhibitor of prodifferentiative Jak/Stat3 signaling, in a lineage-specific manner to prevent precocious astroglial differentiation. In vivo, Zac1 and Socs3 colocalize in the neocortical ventricular zone during incipient astrogliogenesis. Zac1 overexpression in primary NSCs delays astroglial differentiation whereas knockdown of Zac1 or Socs3 facilitates formation of astroglial cells. This negative feedback loop is unrelated to Zac1's cell cycle arrest function and specific to the Jak/Stat3 pathway. Hence, reinstating Jak/Stat3 signaling in the presence of increased Zac1 expression allows for timely astroglial differentiation. Overall, we suggest that the imprinted gene Zac1 curtails astroglial differentiation of NSCs in the developing and adult brain.

Leptin does not induce an inflammatory response in the murine placenta

Leptin is described as a pro-inflammatory signal in fat tissue, which is released from adipocytes and in turn activates immune cells. Also, leptin levels are known to be increased in pregnancies complicated with enhanced inflammatory processes in the placenta. Hence, we assumed that increased leptin amounts might contribute to inducing an inflammatory response in the placenta. To test this hypothesis, pregnant mice were continuously infused with recombinant murine leptin s. c. from day g13 to g16, resulting in a 3-fold increase of maternal circulating serum leptin levels. Dissected placentas were examined for the expression of pro-inflammatory cytokines IL-6 and TNF-alpha and the anti-inflammatory cytokine IL-10 using qPCR analysis. No changes were found except for TNF-alpha, which was slightly elevated upon leptin stimulation. However, TNF-alpha protein levels were not significantly higher in placentas from leptin treated mice. Also, leukocyte infiltration in the labyrinth section of placentas was not increased. In summary, our data demonstrate for the first time that elevated leptin levels alone do not induce an inflammatory response in the placenta.

Expression of selected genes in liver biopsy specimens in relation to early virological response in patients with chronic hepatitis C with HCV mono- and HIV/HCV co-infection

The aim of our study was to evaluate the significance of IL-28B single-nucleotide polymorphism and hepatic expression of IFI27, SOCS3 and miR-122 in order to predict early virological response (EVR) in patients infected with HCV genotype 1 or 4. The study group consisted of 65 patients: 46 with HCV mono- and 19 with HIV/HCV co-infection. Analyses of IL-28B single-nucleotide polymorphism C/T (rs12979860) in the blood and expression of SOCS3, IFI27 and miR-122 in liver biopsy samples obtained before PegIFN and ribavirin treatment were performed by the RT-PCR method. EVR was defined as a >2log decline in HCV viremia at week 12. EVR was associated with a lower expression of IFI27 and a more frequent presence of the IL28BCC genotype. IFI27 expression was lower in patients with the CC genotype, irrespective of EVR. In multivariate logistic regression, only IL28B CC genotype and age above 40 years influenced EVR (OR =5.09 and 0.29 respectively). In contrast to IFI27, expression of miR-122 and SOCS3 in patients with different IL28B genotypes was not statistically significantly different. A correlation between miR-122 and SOCS3 was found (Rho =0.495094 p< 0.0001). Analysis of IFI27, SOCS3 and miR-122 hepatic expression does not provide substantial benefits for the prognosis of EVR. The only independent prognostic factors for EVR are age and IL28B genotype. The prognostic significance of IFI27 expression for EVR is dependent on the genetic polymorphism of IL28B.

Aspirin-triggered Lipoxin A4 attenuates mechanical allodynia in association with inhibiting spinal JAK2/STAT3 signaling in neuropathic pain in rats

Aspirin-triggered Lipoxin A4 (ATL), as a Lipoxin A4 (LXA4) epimer, is endogenously produced by aspirin-acetylated cycloxygenase-2 (COX-2) and plays a vital role in endogenous anti-inflammation via the LXA4 receptor (ALX). Recent investigations have indicated that spinal neuroinflammation and the activation of the Janus Kinase 2 (JAK2)/Signal Transducers and Transcription Activators 3 (STAT3) signaling pathway are involved in neuropathic pain states. However, the effect of ATL on neuroinflammation and JAK2/STAT3 signaling in chronic constriction injury (CCI)-induced neuropathic pain in rats has not been well-studied. The present study demonstrated the anti-inflammatory and analgesic effect of ATL on neuropathic pain and assessed the role of spinal JAK2/STAT3 signaling on the effect of ATL. Intrathecal administration of ATL significantly attenuated mechanical allodynia via spinal ALX and inhibited the upregulation of pro-inflammatory cytokines (IL-1β, IL-6, and TNF-α) on day 7 of CCI surgery. In addition, ATL markedly suppressed the upregulation of p-STAT3 induced by the neuropathic pain. Blockade of JAK2-STAT3 signaling with intrathecal administration of the JAK2 inhibitor AG490 or the STAT3 inhibitor S3I-201 clearly reduced mechanical allodynia and the upregulation of pro-inflammatory cytokines in CCI rats. Interestingly, inhibition of JAK2/STAT3 signaling via ATL or the specific signaling inhibitor (AG49, S3I-201) further promoted the increased expression of suppressor of cytokine signaling 3 (SOCS3) mRNA in the spinal cord induced by CCI surgery. Taken together, our results suggested that the analgesic effect of ATL was mediated by inhibiting spinal JAK2/STAT3 signaling and hence the spinal neuroinflammation in CCI rats.