Secrete Tumor Necrosis Research Articles

Hydrogen sulfide attenuates renal I/R‑induced activation of the inflammatory response and apoptosis via regulating Nrf2‑mediated NLRP3 signaling pathway inhibition.

Renal ischemia/reperfusion (I/R) injury can lead to acute renal failure, delayed graft function and graft rejection. Nucleotide-binding oligomerization domain NOD-like receptor containing pyrin domain 3 (NLRP3)-mediated inflammation participates in the development of renal injury. Nrf2 accelerates NLRP3 signaling pathway activation and further regulates the inflammatory response. In addition, hydrogen sulfide serves a protective role in renal injury; however, the detailed underlying mechanism remains poorly understood. The present study investigated whether Nrf2 and NLRP3 pathway participate in hydrogen sulfide-regulated renal I/R-induced activation of the inflammatory response and apoptosis. Wild-type and Nrf2-knockout (KO) mice underwent surgery to induce renal I/R via clamping of the bilateral renal pedicles. A total of 20 mg/kg MCC950 (an NLRP3 inhibitor) was injected intraperitoneally daily for 14 days prior to surgery. Renal tissue and blood were collected from the I/R model mice to analyze NLRP3 and Nrf2 mRNA expression levels, NLRP3, PYD and CARD domain containing, caspase-1, IL-1β, Nrf2 and heme oxygenase 1 protein expression levels, cell apoptosis, the secretion of tumor necrosis factor-α, IL-1β and IL-6 cytokines and renal histopathology and function. Renal I/R activated the NLRP3 and Nrf2 signaling pathways. Conversely, MCC950 treatment inhibited activation of the NLRP3 signaling pathway, and prevented I/R-induced renal injury, release of cytokines and apoptosis in renal I/R model mice. Sodium hydrosulfide (NaHS) not only alleviated upregulation of NLRP3 protein expression levels, but also relieved renal injury, release of cytokines and cell apoptosis induced by renal I/R in wild-type mice, but not in Nrf2-KO mice. NaHS alleviated NLRP3 inflammasome activation, renal injury, the inflammatory response and cell apoptosis via the Nrf2 signaling pathway in renal I/R model mice.

Proinflammatory macrophages impair skeletal muscle differentiation in obesity through secretion of tumor necrosis factor‐α via sustained activation of p38 mitogen‐activated protein kinase

Obesity is associated with skeletal muscle loss and impaired myogenesis. Increased infiltration of proinflammatory macrophages in skeletal muscle is noted in obesity and is associated with muscle insulin resistance. However, whether the infiltrated macrophages can contribute to obesity-induced muscle loss is unclear. In this study, we investigate macrophage and muscle differentiation markers in the quadriceps (QC), gastrocnemius, tibia anterior, and soleus muscles from obese mice that were fed a high-fat diet for 16 weeks. Then, we examined the effect and mediator of macrophage-secreted factors on myoblast differentiation in vitro. We found markedly increased levels of proinflammatory macrophage markers (F4/80 and CD11c) in the QC muscle compared with the other three muscle groups. Consistent with the increased levels of proinflammatory macrophage infiltration, the QC muscle also showed a significant reduction in the expression of muscle differentiation makers MYOD1 and myosin heavy chain. In in vitro studies, treatment of C2C12 myoblasts with Raw 264.7 macrophage-conditioned medium (CM) significantly promoted cell proliferation and inhibited myoblast differentiation. Neutralization of tumor necrosis factorα (TNF-α) in Raw 264.7 macrophage CM reversed the reduction of myoblast differentiation. Finally, we found that both macrophage CM and TNF-α induced sustained activation of p38 mitogen-activated protein kinase (MAPK) in C2C12 myoblasts. Together, our findings suggest that the increased infiltration of proinflammatory macrophages could contribute toward obesity-induced muscle loss by secreting inflammatory cytokine TNF-α via the p38 MAPK signaling pathway.

Antioxidant and immunostimulatory activities of polysaccharides extracted from Tremella aurantialba mycelia.

In the present study, the physiochemical and biological properties of crude mycelium polysaccharide (CMCP) and purified mycelium polysaccharide (MCP) extracted from the Tremella aurantialba mycelium were investigated. A series of physiochemical properties were determined, including the total sugar, uronic acid and protein content, monosaccharide composition and structure, and molecular weight. The reducing power and scavenging activity of 2,2-diphenyl-1-picrylhydrazyl (DPPH) and hydroxyl radicals were determined to investigate the antioxidant activity of CMCP and MCP. Furthermore, the immunostimulatory activity of the polysaccharides was evaluated by detecting the effects of CMCP and MCP on proliferation, nitric oxide (NO) production and cytokine secretion by RAW264.7 cells. The chemical analysis revealed that MCP had a molecular weight of 4.3x104g/mol and was composed primarily of D‑glucose, D‑galactose and D‑mannose. The total carbohydrate contents of MCP and CMCP were 86.59 and 11.92%, respectively. Compared with CMCP, MCP demonstrated improved antioxidant properties. In addition, MCP induced RAW264.7 macrophage proliferation, NO production and secretion of tumor necrosis factor‑α, interleukin (IL)‑1 and IL‑6. These findings suggest that the total carbohydrate content may contribute to the improvement of antioxidant and immunostimulatory activities of MCP.

Polyinosinic-polycytidylic acid inhibits the differentiation of mouse preadipocytes through pattern recognition receptor-mediated secretion of tumor necrosis factor-α.

Viral infections can disturb the functions of adipose tissues and thus result in metabolic diseases. Polyinosinic-polycytidylic acid (poly(I:C)), a synthetic analog of viral double-stranded RNA, induces innate antiviral responses by mimicking viral infection through the activation of pattern recognition receptors (PRRs) such as Toll-like receptor 3 (TLR3), retinoic acid-inducible gene I (RIG-I) and melanoma differentiation-associated gene 5 (MDA5). Poly(I:C) also inhibits the differentiation of mouse preadipocytes but the mechanism underlying this process remains unclear. In this study, poly(I:C) inhibited preadipocyte differentiation in a dose-dependent manner, but not in a time-dependent manner. Endogenously transfected poly(I:C) severely impaired the adipogenesis of preadipocytes compared with exogenously added poly(I:C). Low concentration of tumor necrosis factor-α (TNF-α) could effectively inhibit the preadipocyte differentiation. The effect of exogenously added poly(I:C) on inhibition of differentiation was significantly diminished in the preadipocytes of TLR3 knockout mice. By contrast, endogenously transfected poly(I:C) still inhibited the differentiation of TLR3-deficient preadipocytes. Hence, MDA5/RIG-I signaling was involved in the poly(I:C)-induced inhibition of preadipocyte differentiation. The effect of poly(I:C) stimulation, either through endogenous transfection or exogenous addition, on inhibition of differentiation was significantly diminished in the preadipocytes of TNF-α knockout mice. These results confirmed the evidence that poly(I:C) inhibited the differentiation of mouse preadipocytes through PRR-mediated secretion of TNF-α.

2,3,7,8‐Tetrachlorodibenzo‐p‐dioxin promotes astrocyte activation and the secretion of tumor necrosis factor‐α via PKC/SSeCKS‐dependent mechanisms

2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is a ubiquitous environmental pollutant that could induce significant toxic effects in the human nervous system. However, the underlying molecular mechanism has not been entirely elucidated. Reactive astrogliosis has implicated in various neurological diseases via the production of a variety of pro-inflammatory mediators. Herein, we investigated the potential role of TCDD in facilitating astrocyte activation and the underlying molecular mechanisms. We showed that TCDD induced rapid astrocyte activation following TCDD exposure, which was accompanied by significantly elevated expression of Src-Suppressed-C Kinase Substrate (SSeCKS), a protein involved in protein kinase C (PKC)-mediated Nuclear Factor kappa B signaling, suggesting a possible involvement of PKC-induced SSeCKS activation in TCDD-triggered reactive astroglia. In keeping with the finding, we found that the level of phosphorylated Nuclear Factor kappa B p65 was remarkably increased after TCDD treatment. Furthermore, interference of SSeCKS attenuated TCDD-induced inducible nitric oxide synthase, glial fibrillary acidic protein, phospho-p65 expression, and tumor necrosis factor-α secretion in astrocytes. In addition, pre-treatment with PKC inhibitor also attenuated TCDD-induced astrocyte activation, as well as SSeCKS expression. Interestingly, we found that TCDD treatment could lead to SSeCKS perinuclear localization, which could be abolished after treatment with PKC inhibitor. Finally, we showed that inhibition of PKC activity or SSeCKS expression would impair TCDD-triggered tumor necrosis factor-α secretion. Our results suggested that TCDD exposure could lead to astrocyte activation through PKC/SSeCKS-dependent mechanisms, highlighting that astrocytes might be important target of TCDD-induced neurotoxicity. 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) elicits neurotoxic effects. Here, we show TCDD induces pro-inflammatory responses in astrocytes. TCDD initiates an increase of [Ca2+]i, followed by the activation of PKC, which then induces the activation of Src-suppressed C-kinase substrate (SSeCKS). SSeCKS promotes NF-κB activation and the secretion of TNF-α and nitric oxide in astrocytes.

Human multipotent stromal cells attenuate lipopolysaccharide-induced acute lung injury in mice via secretion of tumor necrosis factor-α-induced protein 6

IntroductionMultipotent stromal cells (MSCs) are currently in clinical trials for a number of inflammatory diseases. Recent studies have demonstrated the ability of MSCs to attenuate inflammation in rodent models of acute lung injury (ALI) suggesting that MSCs may also be beneficial in treating ALI.MethodsTo better understand how human MSCs (hMSCs) may act in ALI, the lungs of immunocompetent mice were exposed to lipopolysaccharide (LPS) and four hours later bone marrow derived hMSCs were delivered by oropharyngeal aspiration (OA). The effect of hMSCs on lung injury was assessed by measuring the lung wet/dry weight ratio and total protein in bronchoalveolar lavage (BAL) fluid 24 or 48 h after LPS. BAL fluid was also analyzed for the presence of inflammatory cells and cytokine expression by multiplex immunoassay. Microarray analysis of total RNA isolated from treated and untreated lungs was performed to elucidate the mechanism(s) involved in hMSC modulation of lung inflammation.ResultsAdministration of hMSCs significantly reduced the expression of pro-inflammatory cytokines, neutrophil counts and total protein in bronchoalveolar lavage. There was a concomitant reduction in pulmonary edema. The anti-inflammatory effects of hMSCs were not dependent on localization to the lung, as intraperitoneal administration of hMSCs also attenuated LPS-induced inflammation in the lung. Microarray analysis revealed significant induction of tumor necrosis factor (TNF)-α-induced protein 6 (TNFAIP6/TSG-6) expression by hMSCs 12 h after OA delivery to LPS-exposed lungs. Knockdown of TSG-6 expression in hMSCs by RNA interference abrogated most of their anti-inflammatory effects. In addition, intra-pulmonary delivery of recombinant human TSG-6 reduced LPS-induced inflammation in the lung.ConclusionsThese results show that hMSCs recapitulate the observed beneficial effects of rodent MSCs in animal models of ALI and suggest that the anti-inflammatory properties of hMSCs in the lung are explained, at least in part, by activation of hMSCs to secrete TSG-6.

Effect of Prostaglandin E Receptor Subtype EP4 Selective Agonist on the Secretion of Tumor Necrosis Factor‐α by Macrophages in Acute Ethanol‐Loaded Rats

Background: It is suggested that endotoxin and proinflammatory cytokines play an important role in the development and progression of alcoholic liver disease. Recently, a prostaglandin receptor subtype EP4 agonist with cytoprotective effect has been developed. We examined the efficacy of an EP4 agonist ONO‐AE1‐437 on tumor necrosis factor‐α (TNF‐α) secretion of Kupffer cells, splenic macrophages, and alveolar macrophages in acute ethanol‐loaded rats.Methods: Kupffer cells, splenic macrophages, and alveolar macrophages were isolated from control and acute ethanol‐loaded rats (5 mg/g body weight of ethanol, intraperitoneally). After the preculture in the medium that containing 0, 0.1, 1, 10, or 100 nmol/liter of ONO‐AE1‐437, TNF‐α secretion of these cells stimulated by 100 ng/ml of endotoxin was determined for 3 hr.Results: The amount of TNF‐α secreted from alveolar macrophages was largest in both the control and the acute ethanol‐loaded rats. Acute ethanol load enhances TNF‐α secretion of splenic macrophages. The addition of ONO‐AE1‐437 significantly inhibited TNF‐α secretion of Kupffer cells and splenic macrophages in both the control and the acute ethanol‐loaded rats. Alveolar macrophages were less affected.Conclusions: An EP4 agonist ONO‐AE1‐437 suppresses excess TNF‐α secretion from macrophages and seems promising for future trial in patients with severe alcoholic hepatitis.

Stachys riederi Inhibits Mast Cell‐Mediated Acute and Chronic Allergic Reactions

The effect of aqueous extract of Stachys riederi var. japonica Miq. (Labiatae) (SRAE) on the mast cell‐mediated allergic and inflammatory reactions were investigated. SRAE inhibited systemic allergic reaction induced by compound 48/80. SRAE dose‐dependently inhibited passive cutaneous anaphylaxis (PCA) activated by anti‐dinitrophenyl (DNP) IgE. SRAE also dose‐dependently inhibited the histamine release from rat peritoneal mast cells (RPMC) activated by compound 48/80 or anti‐DNP IgE. Moreover, SRAE inhibited the secretion of tumor necrosis factor‐α (TNF‐α) and interleukin (IL)‐6 in phorbol 12‐myristate 13‐acetate (PMA) plus calcium ionophore A23187‐stimulated human mast cells (HMC‐1 cells). These results provide evidences that SRAE may be beneficial in the treatment of acute and chronic allergic diseases.

Isodon japonicus Inhibits Mast Cell‐Mediated Immediate‐Type Allergic Reactions

The effect of aqueous extract of Isodon japonicus Hara (Labiatae) (IJAE) on mast cell‐mediated immediate‐type allergic reactions was investigated. IJAE inhibited systemic allergic reaction induced by compound 48/80. When IJAE was pretreated at the same concentrations with systemic allergic reaction test, the plasma histamine levels were reduced in a dose‐dependent manner. IJAE also inhibited local allergic reaction activated by anti‐dinitrophenyl (DNP) IgE antibody. IJAE dose‐dependently inhibited the histamine release from rat peritoneal mast cells (RPMC) activated by compound 48/80 or anti‐DNP IgE. IJAE inhibited the secretion of tumor necrosis factor‐α (TNF‐α) and interleukin (IL)‐6 in phorbol 12‐myristate 13‐acetate (PMA) plus calcium ionophore A23187‐stimulated human mast cell line (HMC‐1) cells. In addition, the expression of TNF‐α mRNA in HMC‐1 cells was inhibited by IJAE. These results indicate that IJAE may be beneficial in the regulation of immediate‐type allergic reaction.

Effect of Alcohol on the Secretion of Tumor Necrosis Factor‐α by Macrophages in the Presence of Rat Serum

Background It is suggested that endotoxin, proinflammatory cytokines, and lipopolysaccharide‐binding protein (LBP) play an important role in the development of alcoholic liver disease. Our previous study showed that splenic macrophages were important for endotoxin uptake and excessive production of tumor necrosis factor (TNF) in rats given large amounts of alcohol. To determine the pathophysiological roles of macrophages in alcoholic liver disease, we examined the effect of ethanol on TNF‐α secretion of rat Kupffer cells, alveolar macrophages, and peritoneal macrophages in the presence or absence of LBP.Methods Kupffer cells, alveolar macrophages, and peritoneal macrophages were isolated from male Sprague Dawley rats. After the preculture in the medium containing 0, 10, 50, and 100 mmol/liter of ethanol, TNF‐α secretion by these cells incubated with 100 ng/ml of endotoxin in the presence or absence of LBP (1% rat serum) was determined.Results In the absence of LBP, an addition of ethanol to the medium suppressed TNF‐α secretion of alveolar macrophages. Kupffer cells and peritoneal macrophages were less affected. Addition of LBP led to marked enhancement (7‐ to 24‐fold) of TNF‐α secretion of macrophages either with or without ethanol in the medium. Although ethanol tended to suppress TNF‐α secretion of these cells, alveolar macrophages were less affected in the presence of LBP.Conclusions Serum LBP enhances the secretion of TNF‐α by macrophages. Alveolar macrophages may be important for excessive production of TNF‐α in chronic alcoholics with endotoxemia.

Characterization of B61, the Ligand for the Eck Receptor Protein-Tyrosine Kinase

B61 was originally described as a novel secreted tumor necrosis factor-alpha-inducible gene product in endothelial cells (Holzman, L. B., Marks, R. M., and Dixit, V. M. (1990) Mol. Cell. Biol. 10, 5830-5838). It was recently discovered that soluble recombinant B61 could serve as a ligand for the Eck receptor protein-tyrosine kinase, a member of the Eph/Eck subfamily of receptor protein-tyrosine kinases (Bartley, T.D., Hunt, R. W., Welcher, A. A., Boyle, W. J., Parker, V. P., Lindberg, R. A., Lu, H. S., Colombero, A. M., Elliott, R. L., Guthrie, R. A., Holst, P. L., Skrine, J. D., Toso, R. J., Zhang, M., Fernandez, E., Trail, G., Yarnum, B., Yarden, Y., Hunter, T., and Fox, G. M. (1994) Nature 368, 558-560). We now show that B61 can also exist as a cell surface glycosylphosphatidyl-inositol-linked protein that is capable of activating the Eck receptor protein-tyrosine kinase, the first such report of a receptor protein-tyrosine kinase ligand that is glycosylphosphatidylinositol-linked. In addition, the expression patterns of B61 and Eck during mouse ontogeny were determined by in situ hybridization. Both were found to be highly expressed in the developing lung and gut, while Eck was preferentially expressed in the thymus. Finally, the gene for B61 was localized to a specific position on mouse chromosome 3 by interspecific back-cross analysis.

Inhibition of Tumor Necrosis Factor‐α and β Secretion by Lymphokine Activated Killer Cells by Transforming Growth Factor‐β

Transforming growth factor‐β (TGF‐β) has a variety of immunosuppressive properties. We investigated the effect of TGF‐β secreted by glioblastoma (T98G) cells on the secretion of tumor necrosis factor‐α and ‐β (TNFs) by lymphokine activated killer (LAK) cells stimulated with tumor cells. The supernatant from T98G cells was preincubated with anti‐TGF‐βl and ‐β2 neutralizing antibodies or untreated, and added to a coculture of LAK and Daudi cells. The neutralizing antibodies were added to LAK/Daudi and LAK culture, and natural human TGF‐β and recombinant human TGF‐β were also added to the LAK/Daudi culture. LAK cells were also cultured with T98G cells, of which the supernatant contained both active and latent forms of TGF‐/β1 and TGF‐β2, and the neutralizing antibodies were added to the coculture. TNFs activity in the supernatants from LAK/ Daudi cultures was examined by a specific bioassay. Addition of the supernatant from T98G cells to LAK/Daudi culture resulted in the inhibition of TNFs secretion by LAK cells. The inhibition was abrogated by the pretreatment of the supernatants with the anti‐TGF‐β antibodies. Addition of TGF‐β and TGF‐β to LAK/Daudi culture inhibited TNFs secretion by LAK cells in a dose‐dependent manner. Addition of anti‐TGFβ‐ antibodies to LAK culture resulted in an increase of TNFs secretion. These results suggest that, if tumor cells have the capacity to convert TGF‐β from a latent to an active form, the active TGF‐β suppresses TNFs secretion by LAK cells stimulated with the tumor cells, and that TGF‐β secreted and activated by glioblastoma cells suppresses the propagation of immune reaction by inhibiting TNFs secretion by activated lymphocytes adjacent to tumor cells.