Induced Secretion (induced + secretion)

Distribution by Scientific Domains

Selected Abstracts

Differential In Vitro Secretion of Gonadotropin-Releasing Hormone (GnRH) and [Hydroxyproline9]GnRH from the Rat Hypothalamus During Postnatal Development

L. Rochdi
Abstract The differential secretion of gonadotropin-releasing hormone (GnRH) and [hydroxyproline9]GnRH (HypGnRH) has been recently reported from the adult rat hypothalamus. We report here in vitro cosecretion of HypGnRH and GnRH by the hypothalamus of 2,45 day-old-rats and provide evidence that they are differentially regulated throughout development. The secretion of both forms of GnRH was increased in a dependent manner during depolarization by high K+ solutions, and was stimulated by forskolin and 12- O -tetradecanoylphorbol-13-acetate (TPA), activators of adenylate cyclase and protein kinase C pathways, respectively. The proportion of HypGnRH in the release of GnRH-like peptides remained stable and high (33,40%) under basal and K+ -induced conditions until days 13 and 21, respectively. By contrast, the proportion of HypGnRH in the total GnRH-like content of the developing hypothalamus continuously decreased (from 37% to 14%). Similarly, the proportion of HypGnRH: total GnRH-like material released remained stable in TPA- (30%) and forskolin- (50%) induced secretion until postnatal day 8. Evaluation of release over tissue store ratios revealed a 1.3-to 2.8-fold higher release of HypGnRH compared to GnRH according to the different secretions and postnatal periods examined. The preferential recruitment of HypGnRH was maintained under basal and K+ conditions during postnatal development, but it disappeared under TPA stimulation from day 13 onwards. After forskolin stimulation, the preferential mobilization of HypGnRH was markedly reduced from day 2 to day 13 but recovered its high perinatal level during puberty. Taken together, our results support the hypothesis that HypGnRH may play a specific role in development. In addition, a specific function of this peptide taking place during puberty through the activation of the adenylate cyclase pathway is suggested. [source]

Effects of statins on microglia

Catharina Lindberg
Abstract High serum cholesterol level has been shown as one of the risk factors for Alzheimer's disease (AD), and epidemiological studies indicate that treatment with cholesterol-lowering substances, statins, may provide protection against AD. An acute-phase reaction and inflammation, with increased levels of proinflammatory cytokines, are well known in the AD brain. Notably, there is evidence for antiinflammatory activities of statins, such as reduction in proinflammatory cytokines. Consequently, it is of interest to analyze the effects of statins on microglia, the main source of inflammatory factors in the brain, such as in AD. The aims of this study were to determine the effects of statins (atorvastatin and simvastatin) on microglial cells with regard to the secretion of the inflammatory cytokine interleukin-6 (IL-6) and cell viability after activation of the cells with bacterial lipopolysaccharides (LPS) or ,-amyloid1,40 (A,1,40) and in unstimulated cells. Cells of the human microglial cell line CHME-3 and primary cultures of rat neonatal cortical microglia were used. Incubation with LPS or A,1,40 induced secretion of IL-6, and A,1,40, but not LPS, reduced cell viability. Both atorvastatin and simvastatin reduced the basal secretion of IL-6 and the cell viability of the microglia, but only atorvastatin reduced LPS- and A,1,40 -induced IL-6 secretion. Both statins potentiated the A,1,40 -induced reduction in cell viability. The data indicate the importance of also considering the microglial responses to statins in evaluation of their effects in AD and other neurodegenerative disorders with an inflammatory component. © 2005 Wiley-Liss, Inc. [source]

Pregnancy-Specific Glycoproteins Function as Immunomodulators by Inducing Secretion of IL-10, IL-6 and TGF-,1 by Human Monocytes

PROBLEM: Low levels of pregnancy-specific glycoproteins (PSGs) in maternal serum have been correlated with complications of pregnancy. We investigated the ability of human PSGs to regulate in vitro production of cytokines. METHOD OF STUDY: Human monocytes and murine RAW 264.7 cells were treated with recombinant PSG1, PSG6, PSG11, or a truncated PSG6 consisting of only the N-terminal domain (PSG6N). Cytokine production in response to PSG-treatment was measured by ELISA and/or reverse transcriptase-PCR. RESULTS: All PSGs tested induced secretion of interleukin (IL)-10, IL-6 and transforming growth factor (TGF)-,1 by both human and murine cells, but not IL-1,, tumor necrosis factor (TNF)-, or IL-12. The N-terminal domain of PSG6 was sufficient for induction of monocyte cytokine secretion. Induction of IL-10 and IL-6 was preceded by an increase in the specific mRNAs. CONCLUSIONS: PSG1, PSG6, PSG6N, and PSG11 induce dose-dependent secretion of anti-inflammatory cytokines by human monocytes. Human and murine PSGs exhibit cross-species activity. Our results are consistent with a role for PSGs in modulation of the innate immune system. [source]

Galectin 3 induces a distinctive pattern of cytokine and chemokine production in rheumatoid synovial fibroblasts via selective signaling pathways

Andrew Filer
Objective High expression of galectin 3 at sites of joint destruction in rheumatoid arthritis (RA) suggests that galectin 3 plays a role in RA pathogenesis. Previous studies have demonstrated the effects of galectins on immune cells, such as lymphocytes and macrophages. This study was undertaken to investigate the hypothesis that galectin 3 induces proinflammatory effects in RA by modulating the pattern of cytokine and chemokine production in synovial fibroblasts. Methods Matched samples of RA synovial and skin fibroblasts were pretreated with galectin 3 or tumor necrosis factor , (TNF,), and the levels of a panel of cytokines, chemokines, and matrix metalloproteinases (MMPs) were determined using enzyme-linked immunosorbent assays and multiplex assays. Specific inhibitors were used to dissect signaling pathways, which were confirmed by Western blotting and NF-,B activation assay. Results Galectin 3 induced secretion of interleukin-6 (IL-6), granulocyte,macrophage colony-stimulating factor, CXCL8, and MMP-3 in both synovial and skin fibroblasts. By contrast, galectin 3,induced secretion of TNF,, CCL2, CCL3, and CCL5 was significantly greater in synovial fibroblasts than in skin fibroblasts. TNF, blockade ruled out autocrine TNF,-stimulated induction of chemokines. The MAPKs p38, JNK, and ERK were necessary for IL-6 production, but phosphatidylinositol 3-kinase (PI 3-kinase) was required for selective CCL5 induction. NF-,B activation was required for production of both IL-6 and CCL5. Conclusion Our findings indicate that galectin 3 promotes proinflammatory cytokine secretion by tissue fibroblasts. However, galectin 3 induces the production of mononuclear cell,recruiting chemokines uniquely from synovial fibroblasts, but not matched skin fibroblasts, via a PI 3-kinase signaling pathway. These data provide further evidence of the role of synovial fibroblasts in regulating the pattern and persistence of the inflammatory infiltrate in RA and suggest a new and important functional consequence of the observed high expression of galectin 3 in the rheumatoid synovium. [source]

The Critical Role of IL-12p40 in Initiating, Enhancing, and Perpetuating Pathogenic Events in Murine Experimental Autoimmune Neuritis

Lei Bao
Interleukin 12 (IL-12) is a proinflammatory cytokine with important immunoregulatory activities and is critical in determining the differentiation and generation of Th1 cells. For the present study, we investigated the role of endogenous IL-12 in the pathogenesis of experimental autoimmune neuritis (EAN), which is a CD4+ T-cell mediated autoimmune inflammatory disease of the peripheral nervous system. EAN is used as an animal model for Guillain-Barré syndrome of humans. Here, EAN was established in IL-12 p40 deficient mutant (IL-12 -/- ) C57BL/6 mice by immunization with P0 peptide 180,199, a purified component of peripheral nerve myelin, and Freund's complete adjuvant. In these IL-12 -/- mice the onset of clinical disease was delayed, and the incidence and severity of EAN were significantly reduced compared to that in wild-type mice. The former group's clinical manifestations were associated with less P0-peptide 180,199 induced secretion of interferon-, (IFN-,) by splenocytes in vitro and low production of anti-P0-peptide 180,199 IgG2b antibodies in serum. Fewer IFN-, and TNF-, producing cells, but more cells secreting IL-4, were found in sciatic nerve sections from IL-12 -/- mice, consistent with impaired Th1 functions and response. However, the IL-12 deficiency appeared not to affect P0 peptide 180,199-specific T-cell proliferation. These results indicate that IL-12 has a major role in the initiation, enhancement and perpetuation of pathogenic events in EAN by promoting a Th1 cell-mediated immune response and suppressing the Th2 response. This information augments consideration of IL-12 as a therapeutic target in Guillain-Barré syndrome and other T-cell-mediated autoimmune diseases. [source]

Anti-inflammatory properties of heat shock protein 70 and butyrate on Salmonella -induced interleukin-8 secretion in enterocyte-like Caco-2 cells

J. J. Malago
Summary Intestinal epithelial cells secrete the chemokine interleukin (IL)-8 in the course of inflammation. Because heat shock proteins (Hsps) and butyrate confer protection to enterocytes, we investigated whether they modulate Salmonella enterica serovar Enteritidis (S. serovar Enteritidis)-induced secretion of IL-8 in enterocyte-like Caco-2 cells. Caco-2 cells incubated with or without butyrate (0,20 m M, 48 h) were infected with S. serovar Enteritidis after (1 h at 42°C, 6 h at 37°C) or without prior heat shock (37°C). Levels of Hsp70 production and IL-8 secretion were analysed using immunostaining of Western blots and enzyme-linked immunosorbent assay (ELISA), respectively. The cells secreted IL-8 in response to S. serovar Enteritidis and produced Hsp70 after heat shock or incubation with butyrate. The IL-8 secretion was inhibited by heat shock and butyrate concentrations as low as 0·2 m M for crypt-like and 1 m M for villous-like cells. In a dose-dependent manner, higher butyrate concentrations enhanced IL-8 secretion to maximal levels followed by a gradual but stable decline. This decline was associated with increasing production of Hsp70 and was more vivid in crypt-like cells. In addition, the higher concentrations abolished the heat shock inhibitory effect. Instead, they promoted the IL-8 production in heat-shocked cells even in the absence of S. serovar Enteritidis. We conclude that heat shock and low concentrations of butyrate inhibit IL-8 production by Caco-2 cells exposed to S. serovar Enteritidis. Higher butyrate concentrations stimulate the chemokine production and override the inhibitory effect of the heat shock. The IL-8 down-regulation could in part be mediated via production of Hsp70. [source]