Lysophosphatidylserine receptor P2Y10: A G protein-coupled receptor that mediates eosinophil degranulation.

BACKGROUND: P2Y10, along with GPR34 and GPR174, is a G protein-coupled receptor that is activated by an endogenous lipid mediator lysophosphatidylserine (LysoPS). Its expression pattern and its function are completely unknown. We have previously shown that P2Y10 is one of the highly up-regulated genes at the late differentiation stage during in vitro eosinophilopoiesis. OBJECTIVE: We explored the expression and functions of P2Y10 in human cord blood (CB)-derived and peripheral blood (PB) eosinophils. METHODS: Real-time PCR, FACS, Western blot, ELISA, and chemotaxis assays were performed to determine the expression and function of P2Y10. RESULTS: As CB cells differentiated towards eosinophils, P2Y10 mRNA and protein were abundantly expressed. P2Y10 was the most highly expressed in the granulocytes from PB, to a lesser extent in monocytes, and least in lymphocytes. Further fractionation of granulocytes revealed that eosinophils express P2Y10 much more strongly than do neutrophils. PB eosinophils solely expressed P2Y10 among the three LysoPS receptors, while PB neutrophils expressed the three at comparable levels. LysoPS activated both CB and PB eosinophils to induce a robust ERK phosphorylation. Importantly, LysoPS was capable of triggering degranulation of ECP in PB eosinophils. This response was significantly reduced by pharmacological inhibitors of TNF-alpha-converting enzyme (TACE), epidermal growth factor receptor (EGFR), and ERK1/2, which were known to be required in P2Y10-mediated signalling pathways. However, LysoPS had no effect on chemotaxis, differentiation, or eosinophil survival. CONCLUSIONS AND CLINICAL RELEVANCE: LysoPS provokes eosinophil degranulation through P2Y10. Therefore, P2Y10 is a potential therapeutic target to control eosinophil-associated diseases.

Emergence of Enterococcus species in the infectious microorganisms cultured from patients with endophthalmitis in South Korea.

PURPOSE: To investigate the microorganisms in culture-proven endophthalmitis and their susceptibilities to antimicrobial agents commonly used in South Korea. METHODS: Medical records of consecutive patients with culture-proven endophthalmitis at eight institutions between 1 January 2004 and 31 July 31 2010 were reviewed. Four categories of endophthalmitis were studied: postoperative, posttraumatic, endogenous, and unspecified. Outcome measures were culture-proven infectious organisms, antimicrobial susceptibilities, and final visual acuity in the patients. RESULTS: A total of 93 microorganisms were identified from 103 patients during the study period. The positive culture rate was 59.2 % (103/174). The most common organisms identified were Enterococcus faecalis (in 20.8 % of patients, 20/96), Staphylococcus epidermidis (18.8 %, 18/96), other coagulase-negative staphylococci (10.4 %, 10/96), Pseudomonas aeruginosa (6.3 %, 6/96), and Klebsiella pneumoniae (6.3 %, 6/96). Two cases of Enterococcus faecium (2.1 %) were recognized. Overall, 70 of 96 (73.0 %) isolates were Gram-positive bacteria, 22 (23.0 %) were Gram-negative bacteria, and 4 (4.2 %) were fungi. The most common organisms resulting in reduced light perception were E. faecalis and K. pneumoniae. CONCLUSIONS: The emergence of E. faecalis in endophthalmitis is mainly caused by the high incidence of E. faecalis in postoperative endophthalmitis. This increase also impacts the final visual acuity of the patients.

An increase in cancer stem cell population after primary systemic therapy is a poor prognostic factor in breast cancer.

BACKGROUND: The cancer stem cell (CSC) hypothesis has important clinical implications for cancer therapeutics because of the proposed role of CSCs in chemoresistance. The aim of this study was to investigate changes in the CSC populations before and after primary systemic therapy (PST) and their prognostic role in human breast cancer. METHODS: Paired samples (before and after PST) of breast cancer tissue were obtained from clinical stage II or III patients (n=92) undergoing PST with the regimen of doxorubicin plus docetaxel (AD) (n=50) or doxorubicin plus cyclophosphamide (AC) (n=42) and subsequent breast resection. The proportions of putative CSCs with CD44+/CD24- or aldehyde dehydrogenase 1+ (ALDH1+) phenotypes were determined by immunohistochemistry. RESULTS: A higher proportion of CD44+/CD24- tumour cells and ALDH1 positivity in pre-chemotherapy tissue was correlated with higher histologic grade, oestrogen receptor (ER) negativity, high Ki-67 proliferation index and basal-like subtype of breast cancer. Aldehyde dehydrogenase 1 positivity in pre-chemotherapy biopsy was also associated with a higher rate of pathologic complete response following PST. In comparisons of putative CSC populations before and after PST, the proportions of CD44+/CD24- and ALDH1+ tumour cells were significantly increased after PST. The cases with increased CD44+/CD24- tumour cell populations after PST showed high Ki-67 proliferation index in post-chemotherapy specimens and those with increased ALDH1+ tumour cell population after PST were associated with ER negativity and p53 overexpression. Furthermore, cases showing such an increase had significantly shorter disease-free survival time than those with no change or a reduced number of CSCs, and the survival difference was most notable with regard to the changes of ALDH1+ tumour cell population in the patients who received AC regimen. CONCLUSION: The present study provides the clinical evidence that the putative CSCs in breast cancer are chemoresistant and are associated with tumour progression, emphasising the need for targeting of CSCs in the breast cancer therapeutics.

Genetic effect of single-nucleotide polymorphisms in the PPARGC1B gene on airway hyperreactivity in asthmatic patients.

BACKGROUND: Peroxisome proliferator-activated receptor gamma coactivator 1 beta (PPARGC1B) is a co-activator for intracellular receptors such as the estrogen receptor, PPAR, and glucocorticoid receptor, which are involved in asthma development. OBJECTIVES: Genetic association of single-nucleotide polymorphisms (SNPs) in the PPARGC1B gene with the risk of asthma and airway hyperreactivity (AHR) was investigated, as well as the functional effects of these SNPs on PPARGC1B gene and protein expression. METHODS: Direct sequencing of DNA from 24 Korean was performed to identify PPARGC1B SNPs. Genotyping was done in 264 controls and 949 asthmatics using single-base extension methods. PPARGC1B mRNA levels were measured using real-time PCR methodology. Luciferase and electrophoretic mobility shift assays (EMSA) were performed to functionally analyse PPARGC1B SNPs on promoter. RESULTS: Eighteen SNPs and one insertion/deletion polymorphism were identified, and seven SNPs were genotyped. No significant difference existed in the distribution of SNPs and haplotypes between the asthmatics and controls. However, the allele frequency of -427C>T and +102525G>A;R265Q showed a significant association with log-transformed PC(20) methacholine values in the asthmatics (P=0.005-0.0004). Real-time PCR demonstrated higher PPARGC1B mRNA levels in asthmatics having -427CC allele than in those having -427TT or CT alleles (P=0.048). The ratio of the mRNA expression for each PPARGC1B exon4-mRNA compared with the wild type was similar in peripheral blood mononuclear cells carrying the +102525G>A allele. Luciferase reporter assays revealed that -427C allele caused higher promoter activity than -427T allele. EMSA demonstrated that -427C allele exhibited stronger binding activity to a nuclear protein in 293T cells than did the -427T allele. CONCLUSIONS AND CLINICAL RELEVANCE: Polymorphisms of -427C>T on the promoter and those of +102525G>A on exon 5 of the PPARGC1B gene may affect the development of AHR through the modulation of PPARGC1B gene products. The PPARGC1B genotypes may serve as genetic markers for AHR.

Differential tumor necrosis factor alpha expression by astrocytes from experimental allergic encephalomyelitis-susceptible and -resistant rat strains.

There is evidence that the cytokine tumor necrosis factor alpha (TNF-alpha) contributes to the pathogenesis of neurological autoimmune diseases such as multiple sclerosis (MS) and experimental allergic encephalomyelitis (EAE). TNF-alpha exerts damaging effects on oligodendrocytes, the myelin-producing cell of the central nervous system (CNS), and myelin itself. We have recently demonstrated TNF-alpha expression from astrocytes induced by lipopolysaccharide (LPS), interferon gamma (IFN-gamma), and interleukin 1 beta (IL-1 beta). Astrocytes secrete TNF-alpha in response to LPS alone, and can be primed by IFN-gamma to enhance LPS-induced TNF-alpha production. IFN-gamma and IL-1 beta, cytokines known to be present in the CNS during neurological disease states, do not induce TNF-alpha production alone, but act synergistically to stimulate astrocyte TNF-alpha expression. Inbred Lewis and Brown-Norway (BN) rats differ in genetic susceptibility to EAE, which is controlled in part by major histocompatibility complex (MHC) genes. We examined TNF-alpha gene expression by astrocytes derived from BN rats (resistant to EAE) and Lewis rats (highly susceptible). Astrocytes from BN rats express TNF-alpha mRNA and protein in response to LPS alone, yet IFN-gamma does not significantly enhance LPS-induced TNF-alpha expression, nor do they express appreciable TNF-alpha in response to the combined stimuli of IFN-gamma/IL-1 beta. In contrast, astrocytes from Lewis rats express low levels of TNF-alpha mRNA and protein in response to LPS, and are extremely responsive to the priming effect of IFN-gamma for subsequent TNF-alpha gene expression. Also, Lewis astrocytes produce TNF-alpha in response to IFN-gamma/IL-1 beta. The differential TNF-alpha production by astrocytes from BN and Lewis strains is not due to the suppressive effect of prostaglandins, because the addition of indomethacin does not alter the differential pattern of TNF-alpha expression. Furthermore, Lewis and BN astrocytes produce another cytokine, IL-6, in response to LPS, IFN-gamma, and IL-1 beta in a comparable fashion. Peritoneal macrophages and neonatal microglia from Lewis and BN rats are responsive to both LPS and IFN-gamma priming signals for subsequent TNF-alpha production, suggesting that differential TNF-alpha expression by the astrocyte is cell type specific. Taken together, these results suggest that differential TNF-alpha gene expression in response to LPS and IFN-gamma is strain and cell specific, and reflects both transcriptional and post-transcriptional control mechanisms.(ABSTRACT TRUNCATED AT 400 WORDS)

Association of angiotensin I-converting enzyme gene polymorphisms with aspirin intolerance in asthmatics.

BACKGROUND: Aspirin-intolerant asthma (AIA) refers to the development of bronchoconstriction in asthmatic individuals following the ingestion of aspirin or other non-steroidal anti-inflammatory drugs (NSAIDs). Angiotensin I-converting enzyme (ACE), a membrane-bound peptidase present in the lung, plays a pivotal role in the metabolism of the endogenous peptides involved in the pathogenesis of asthma. METHODS: We screened a Korean asthma cohort (581 asthmatics including 81 aspirin-intolerant asthmatics and 231 aspirin-tolerant asthmatics, and 181 normal controls) for four single nucleotide polymorphisms (SNPs; -262 A>T and -115 T>C in the 5'-flanking region and +5467 T>C [Pro450Pro] and+11860 A>G [Thr776Thr] in the coding region) and one ins/del (+21288 CT) in the ACE gene. RESULTS: None of the SNPs or haplotypes showed any association with the development of asthma, but they were significantly associated with the risk of AIA. Logistic regression indicated that the frequency of the rare alleles of -262 A>T and -115 T>C was higher in subjects with AIA than in subjects with aspirin-tolerant asthma (ATA) (P=0.003-0.01, P( corr)=0.015-0.05). Subjects homozygous for the rare alleles of -262 A>T and -115 T>C showed a greater decline in forced expiratory volume in 1 s (FEV(1)) after aspirin provocation than those homozygous for the common alleles (P<0.05). A luciferase reporter assay indicated that ACE promoters containing the rare -262 A>T allele possessed lower activity than did those containing the common allele (P=0.009). In addition, ACE promoters bearing the rare -115 T>C allele had no luciferase activity. DNA-protein binding assays revealed a band containing the ACE promoter region (including -262 A) and a protein complex. CONCLUSION: The -262 A>T polymorphism in the promoter of the ACE gene is associated with AIA, and the rare allele of -262 A>T may confer aspirin hypersensitivity via the down-regulation of ACE expression.

Triamcinolone acetonide protects the rat retina from STZ-induced acute inflammation and early vascular leakage.

Streptozotocin (STZ) has been commonly used to induce in vivo and in vitro hyperglycemic diabetes and its toxicity leads to inflammation and vascular injury. Triamcinolone acetonide (TA), as an anti-angiogenic/anti-inflammatory drug, is clinically used to improve the visual acuity in neovascular and edematous ocular diseases. The aim of this study was to investigate the effect of TA on early inflammation and vascular leakage in the retina of STZ-induced hyperglycemic rats. Hyperglycemia was induced in 8-week-old male Sprague-Dawley (SD) rats by a single intraperitoneal injection of STZ (65 mg/kg); only rats with blood glucose levels >13.9 mmol/l 1 day after STZ injection were included in STZ-hyperglycemic group. Sex- and age-matched SD rats injected with buffer were used as the control group. One day before STZ and buffer injection, 2 microl TA (4 mg/ml in saline) and 2 microl saline were intravitreal-injected into the right and the left eyes of rats, respectively. Retinal vascular leakage was measured using the Evans-blue method. Changes in pro-inflammatory target genes, such as tumor necrotic factor (TNF)-alpha, intracellular adhesion molecule (ICAM)-1, and vascular endothelial growth factor (VEGF) were assessed by immunoblottings, immunostaining, and ELISA analyses. Vascular hyperleakage and up-regulation of most pro-inflammatory genes peaked within a few days after STZ injection and had recovered. However, these changes were blocked by TA pretreatment. Our data suggest that TA controls STZ-induced early vascular leakage and temporary pro-inflammatory signals in the rat retina.

A novel human ERK phosphatase regulates H-ras and v-raf signal transduction.

A cDNA encoding a novel human extracellularly-regulated kinase (ERK) phosphatase, designated B59, was isolated from a B5/589 human mammary epithelial cell cDNA library. The 1104 nucleotide open reading frame encodes 368 amino acids including the highly conserved catalytic site sequence of protein phosphotyrosine phosphatases (PTPs), VXVHCXXGXXR, at amino acid position 276-287. The predicted 70 amino acid stretch surrounding the HC motif shares significant sequence identity with other human dual specificity PTPs (dsPTPs), including the known ERK PTPs CL100, PAC1, B23, as well as the dsPTPs VH-1 and VHR. B59 protein synthesized in vitro in a rabbit reticulocyte lysate dephosphorylated rat ERK1 and ERK2 proteins whose phosphorylation had been stimulated by v-mos kinase added to the lysate. Ectopic expression of B59 in NIH3T3 fibroblasts inhibited the induction of an oncogene-responsive promoter by the dominant-activating raf mutant, raf-BXB. Moreover, cotransfection of NIH3T3 cells with B59 inhibited morphological transformation by H-ras and v-raf oncogenes. These results suggest that B59 suppresses the transforming activity of H-ras or v-raf oncogenes through ERK dephosphorylation and inactivation.

Cloning and sequence analysis of the rat tumor necrosis factor-encoding genes.

We have isolated an approximately 22-kb TNF locus (encoding tumor necrosis factor) from a rat genomic library and sequenced the 7105-bp fragment that comprises the TNF-alpha and TNF-beta genes, including their flanking sequences. The two genes are tandemly arranged with TNF-beta 5' to TNF-alpha and separated by approximately 1.1 kb of intergenic space, and each gene consists of four exons and three introns, similar to those of the other species examined thus far. Comparison analysis showed that the rat TNF have high sequence homology with the mouse TNF (TNF-alpha, 86.5%; TNF-beta, 89.3%) and relatively low homology with the human, rabbit, and porcine TNF. The upstream sequence of rat TNF-alpha contains a number of sequence motifs implicated in the expression and regulation of eukaryotic genes, including binding sites for the transcription factors Sp-1, Ap-2, IFN.1 and NF-kappa B. The possible significance of potential regulatory sequence elements found in the rat TNF-alpha in the context of transcriptional regulatory mechanisms is discussed.

Regulation of intercellular adhesion molecule-1 gene expression by tumor necrosis factor-alpha, interleukin-1 beta, and interferon-gamma in astrocytes.

Intercellular adhesion molecule-1 (ICAM-1) is a cell surface glycoprotein which can be induced on astrocytes, the major glial cell of the central nervous system (CNS). In this study, we examined the effect of three proinflammatory cytokines, tumor necrosis factor-alpha (TNF-alpha), interleukin-1 beta (IL-1 beta), and interferon-gamma (IFN-gamma), on the expression of ICAM-1 by primary rat astrocytes. Astrocytes constitutively express ICAM-1 mRNA and protein, which is enhanced by treatment with TNF-alpha, IL-1 beta and IFN-gamma. TNF-alpha is the most potent inducer of ICAM-1 expression, followed by IL-1 beta, then IFN-gamma. Kinetic analysis demonstrated optimum ICAM-1 mRNA expression after a 1-h exposure to TNF-alpha, 2 h exposure to IL-1 beta, and 4 h exposure to IFN-gamma. Peak ICAM-1 protein expression was detected 12-16 h after treatment with TNF-alpha or IL-1 beta, and after a 24-h exposure to IFN-gamma. Nuclear run-on analysis demonstrated that the ICAM-1 gene is transcribed under basal conditions in astrocytes, and that both TNF-alpha and IL-1 beta enhance transcriptional activation of the ICAM-1 gene. ICAM-1 mRNA stability studies determined that basal ICAM-1 mRNA has a half-life of about 1 h, and that TNF-alpha, IL-1 beta and IFN-gamma have a modest effect on stabilization of basal ICAM-1 mRNA expression. These results indicate that under inflammatory conditions in the CNS, such as multiple sclerosis (MS) and experimental allergic encephalomyelitis (EAE), astrocytes can be induced to express the adhesion molecule ICAM-1, which can contribute to inflammatory events within the CNS.

Interleukin-1 beta induction of tumor necrosis factor-alpha gene expression in human astroglioma cells.

Cells that produce tumor necrosis factor-alpha (TNF-alpha) require the presence of signaling molecules since this cytokine is not normally expressed in a constitutive manner. It has been demonstrated that glial cells can produce TNF-alpha; however, the specific inducing molecules and their mechanism(s) of action have not been clearly defined. In this study, we examined the effect of human recombinant interleukin-1 beta (IL-1 beta) on the expression of TNF-alpha by CH235-MG human malignant glioma cells. CH235-MG cells do not constitutively express TNF-alpha mRNA or protein; however, upon stimulation with IL-1 beta, these cells synthesize and secrete biologically active TNF-alpha. IL-1 beta induces the expression of a 1.9 kb TNF-alpha mRNA species. Kinetic analysis demonstrated optimum TNF-alpha mRNA expression after a 4 h exposure to IL-1 beta, and peak TNF-alpha protein production at 18 h. Cycloheximide (CHX), an inhibitor of protein synthesis, markedly increased expression of TNF-alpha mRNA in IL-1 beta stimulated CH235-MG cells, indicating that de novo protein synthesis is not required for astroglioma TNF-alpha gene expression. Nuclear run-off analysis demonstrates that IL-1 beta causes transcriptional activation of the TNF-alpha gene, and CHX enhances IL-1 beta-induced TNF-alpha transcription. Studies of TNF-alpha mRNA stability using actinomycin D show that IL-1 beta-induced TNF-alpha mRNA has a half-life of approximately 30 min, and CHX increases the half-life of IL-1 beta-induced TNF-alpha mRNA to approximately 210 min. These results indicate that IL-1 beta, a cytokine present in the central nervous system during some pathological disease states, is a potent inducer of TNF-alpha in human malignant glioma cells.

Tumor necrosis factor production and receptor expression by a human malignant glioma cell line, D54-MG.

Human malignant gliomas possess some of the same immune-related functions as astrocytes do. For instance, they are capable of secreting various immunoregulatory molecules and expressing HLA-DR antigens on their surface. The human malignant glioma cell line, D54-MG, was used to investigate the proliferative effects of tumor necrosis factor-alpha (TNF-alpha) and the expression of specific surface receptors for TNF-alpha. Additionally, we were interested in examining whether D54-MG cells are capable of synthesizing and secreting biologically active TNF-alpha. D54-MG cells responded in a mitogenic fashion upon incubation with TNF-alpha for 48 h under serum-free conditions. 125I-labeled TNF-alpha was used in this study to investigate the expression of receptors specific for TNF-alpha on D54-MG cells. Scatchard analysis of our receptor binding data produced curvilinear plots indicating there are two distinct receptor sites for TNF-alpha. From these data, we calculated that there are approximately 3500 high affinity and 24,666 low affinity binding sites per cell. Pretreating these cells with interferon-gamma (IFN-gamma) resulted in a 2-fold increase in the number of high affinity binding sites and a moderate increase in the number of low affinity binding sites, with no appreciable change in binding affinity (Kd) of either site. D54-MG cells were unable to constitutively secrete TNF-alpha; however, upon stimulation, these cells synthesize and secrete biologically active TNF-alpha. Polyclonal antisera reactive with human macrophage-derived TNF-alpha neutralized the cytotoxicity of D54-MG-derived TNF-alpha, demonstrating that the cytotoxic activity was in fact due to TNF-alpha. Our observations indicate that TNF-alpha could act in an autocrine fashion to induce the proliferation of this malignant glioma cell line and that TNF-alpha exerts its effect by binding to specific TNF-alpha receptors whose expression was enhanced by IFN-gamma.

The biochemical and molecular characterization of recombinant Bacillus subtilis tripeptidase (PepT) as a zinc-dependent metalloenzyme.

Aminopeptidases catalyze the release of N-terminal amino acid residue from polypeptides and peptides, and most of them are known to be metalloenzymes. A tripeptidase gene (pepT) of Bacillus subtilis was expressed in Escherichia coli, and the resulting recombinant PepT was purified in an active form through sequential chromatographies. The addition of Zn2+ or Co2+ increased the enzymatic activity by approximately two fold. The points at which Zn2+ and Co2+ stimulated a half-maximum activity of the PepT were 650 nM and 1,700 nM, respectively. The measurement of the metal content showed that this enzyme contained 0.26 atom of Zn2+ per molecule with essentially the absence of Co2+ and others, and 0.53 atom of Zn2+ with 1.5-fold increase of activity when reconstituted with Zn2+. Consistent with this result, this enzyme is much readily refolded in the presence of Zn2+ than Co2+. To further delineate the structure and function relations, we made serial deletion mutants and analyzed their enzymatic activities. Of eight deletion mutants, only a mutant lacking the N-terminal 66 amino acid residues retained enzymatic activity. The mutant enzyme, however, required a concentration of Zn2+ ion at least ten-fold higher to reach maximum activity without significantly affecting kinetic parameters such as Km and Vmax compared to the full length PepT. Taken together, these data suggest that the B. subtilis PepT is likely to be a Zn2+-dependent metalloenzyme and that the N-terminal region of the PepT stabilizes Zn2+-binding.

Revascularization of the ischemic colon transplant using the internal mammary vessels.

We describe a successful reconstruction of the esophagus with the isoperistaltic right colon and terminal ileum, which had very poor continuity of the marginal artery. The stomach and the left colon were not available because of corrosive injury and intraabdominal adhesions. The blood supply of the ischemic transplant was augmented by anastomosis of the internal mammary vessels to the iliocolic vessels.

Effect and mechanism of lipopolysaccharide on allergen-induced interleukin-5 and eotaxins production by whole blood cultures of atopic asthmatics.

Interleukin (IL)-5 and eotaxin families regulate the development of eosinophilic inflammation of asthma in a co-operative manner. The exposure to airborne lipopolysaccharide (LPS) induces varying degrees of airflow obstruction and neutrophilic airway inflammation. Production of IL-5 and eotaxin subfamily chemokines was analysed in response to Dermatophagoides pteronyssinus allergen (D.p.) according to the presence of specific IgE to D.p., and investigated the mechanism underlying their LPS-mediated regulation of these cytokines in response to the specific allergen. Peripheral blood cells (PBCs) from asthmatics with (group 1) or without (group 2) specific IgE to D.p. and from non-asthmatics with (group 3) or without (group 4) were stimulated with D.p. or LPS. For LPS-mediated inhibition of IL-5 and eotaxin-2 production, LPS-induced cytokines were added to the D.p.-stimulated PBCs. IL-5 and eotaxin-2, but not eotaxin-1 and 3, were significantly increased by D.p.-stimulated-PBCs from group 1, while only eotaxin-2 was elevated in group 3. Eotaxin-2 production was found in monocytes and correlated with the level of specific IgE to D.p. LPS treatment resulted in the decrease in eotaxin-2 and IL-5 production by the D.p.-stimulated PBCs. LPS-induced IL-10 completely inhibited D.p.-stimulated production of eotaxin-2 and IL-5. The differential responses of the eotaxin family to specific antigens suggest that the predominant role of eotaxin-2 and LPS may attenuate eosinophilic inflammation by inhibiting IL-5 and eotaxin-2 synthesis through IL-10 production.

Triamcinolone suppresses retinal vascular pathology via a potent interruption of proinflammatory signal-regulated activation of VEGF during a relative hypoxia.

We examined the effect of triamcinolone acetonide (TA), a corticosteroid, on the relationship between vascular pathophysiology and vascular endothelial growth factor (VEGF) activation in the retina of a rat model of oxygen-induced retinopathy (OIR). OIR was induced by exposure of hyperoxia (80% oxygen) to Sprague-Dawley (SD) rats from P2 to P14 and then returned to normoxic conditions. TA was intravitreal-injected once into the right eye of OIR rats at P15. Effects of TA on vascular pathophysiology or changes of various genes in response to hypoxia and/or proinflammation under hypoxic retina were assessed by the Evans-blue method, fluorescein isothiocyanate-dextran (FITC-D) infusion, immunoblotting, and ELIZA. TA not only reduced retinal neovascularization and vascular leakage in the OIR-rat retina, but also blocked the induction of hypoxia-response proinflammatory genes before it negatively controlled VEGF activation. These findings suggest a potential that TA suppresses retinal neovascular pathophysiology via proinflammation-mediated activation of VEGF during hypoxia.

Tumor necrosis factor-alpha production by astrocytes. Induction by lipopolysaccharide, IFN-gamma, and IL-1 beta.

Astrocytes have the capacity to secrete or respond to a variety of cytokines including IL-1, IL-6, IL-3, and TNF-alpha. In this study, we have examined the capacity of astrocytes to secrete TNF-alpha in response to a variety of biologic stimuli, particularly cytokines such as IL-1 and IFN-gamma, which are known to be present in the central nervous system during neurologic diseases associated with inflammation. Rat astrocytes do not constitutively produce TNF-alpha, but have the ability to secrete TNF-alpha in response to LPS, and can be primed by IFN-gamma to respond to a suboptimal dose of LPS. IFN-gamma and IL-1 beta alone do not induce TNF-alpha production, however, the combined treatment of IFN-gamma and IL-1 beta results in a striking synergistic effect on astrocyte TNF-alpha production. Astrocyte TNF-alpha protein production induced by a combined treatment of either IFN-gamma/LPS or IFN-gamma/IL-1 beta occurs in a dose- and time-dependent manner, and appears to require a "priming signal" initiated by IFN-gamma, which then renders the astrocyte responsive to either a suboptimal dose of LPS or IL-1 beta. Astrocyte TNF-alpha production by IFN-gamma/LPS stimulation can be inhibited by the addition of anti-rat IFN-gamma antibody, whereas IFN-gamma/IL-1-induced TNF-alpha production is inhibited by antibody to either IFN-gamma or IL-1 beta. Polyclonal antisera reactive with mouse macrophage-derived TNF-alpha neutralized the cytotoxicity of IFN-gamma/LPS and IFN-gamma/IL-1 beta-induced astrocyte TNF-alpha, demonstrating similarities between these two sources of TNF-alpha. We propose that astrocyte-produced TNF-alpha may have a pivotal role in augmenting intracerebral immune responses and inflammatory demyelination due to its diverse functional effects on glial cells such as oligodendrocytes and astrocytes themselves.

Role of protein kinase C activity in tumor necrosis factor-alpha gene expression. Involvement at the transcriptional level.

Primary rat astrocytes express TNF-alpha protein in response to various stimuli including a combined treatment with IFN-gamma and LPS, or IFN-gamma and IL-1 beta. This study was undertaken to further elucidate the mechanisms underlying TNF-alpha gene expression in the astrocyte, and to determine the intracellular signaling pathways involved in IFN-gamma/LPS and/or IFN-gamma/IL-1 beta induction of the TNF-alpha gene. We demonstrate that TNF-alpha mRNA is rapidly induced, and mRNA levels peak after 2 h of stimulation. De novo protein synthesis is not required for TNF-alpha expression because the inclusion of cycloheximide does not prevent expression of the gene and acts to superinduce TNF-alpha mRNA levels. IFN-gamma/LPS induces transcriptional activation of the TNF-alpha gene as assessed by nuclear run-on experiments. Cycloheximide acts to increase both transcription of the TNF-alpha gene and stability of TNF-alpha mRNA thereby resulting in increased TNF-alpha steady state mRNA levels. Two protein kinase C (PKC) inhibitors, H7 and staurosporine, abrogate IFN-gamma/LPS- and IFN-gamma/IL-1 beta-induced TNF-alpha expression in a dose-dependent manner. PKC activity is required for transcription of the TNF-alpha gene, and does not appear to be involved in TNF-alpha mRNA stabilization. Taken together, these data demonstrate that TNF-alpha gene expression in primary rat astrocytes is induced in a PKC-dependent manner.

Role of cAMP-dependent pathway in eosinophil apoptosis and survival.

The survival and apoptosis of eosinophils is of pivotal importance for controlling allergic diseases such as asthma and rhinitis. In this study we have investigated the role for cAMP in regulating eosinophil survival and apoptosis in the absence of eosinophil-active cytokines. The treatment with dibutyryl cyclic AMP (dbcAMP) increased eosinophil survival with a concomitant decrease of apoptosis in a dose-dependent manner. The pretreatment with a protein kinase A (PKA) inhibitor blocked the effects of dbcAMP on survival and apoptosis of eosinophils. The catalytic subunit of PKA was translocated to nucleus in parallel with a robust increase of intracellular cAMP levels upon exposure to dbcAMP but not IL-5, suggesting the separation of PKA activation from the IL-5-induced suppression of eosinophil apoptosis. When eosinophils were treated with pharmacological inhibitors of protein kinases prior to exposure to dbcAMP or IL-5, only the mitogen-activating protein kinase (MAPK) inhibitor, PD098059, was partly able to block dbcAMP-induced augmentation of eosinophil viability, whereas both Janus kinase 2 and MAPK inhibitors effectively interrupted the IL-5-induced prolongation of eosinophil survival. The effects of dbcAMP and these protein kinase inhibitors on eosinophil apoptosis were confirmed by morphologic analysis. We propose that a cAMP-dependent pathway may constitute an important component for regulating eosinophil survival/apoptosisand that cAMP may inhibit eosinophil apoptosis through the activation of PKA and of subsequent MAPK in part.