Cyclooxygenase-2 regulates granulocyte-macrophage colony-stimulating factor, but not interleukin-8, production by human vascular cells: role of cAMP

Myeloid derived suppressor cells in peripheral blood can be a prognostic factor in canine transitional cell carcinoma

Myeloid-derived suppressor cells (MDSCs) are immature cells with immunosuppressive properties found in the tumor microenvironment. MDSCs are divided into two major subsets: polymorphonuclear MDSCs (PMN-MDSCs) and monocytic MDSCs (M-MDSCs). Both MDSC subsets contribute to the creation of an immunosuppressive environment for tumor progression. In humans, patients with high levels of MDSCs show worse outcomes for several types of cancers. However, the association between MDSCs and clinical features has rarely been investigated in canine studies. In the present study, we measured the proportion of PMN-MDSCs and M-MDSCs in the peripheral blood and tumor tissue of dogs with hepatocellular carcinoma (HCC), prostate cancer (PC), transitional cell carcinoma (TCC), lymphoma, and pulmonary adenocarcinoma. Additionally, we examined immunosuppressive ability of PMN-MDSCs and M-MDSCs in peripheral blood mononuclear cells of TCC case on CD4+, CD8+ and interferon-γ+ cells and investigated the relationships of MDSCs with clinical features and outcomes. PMN-MDSCs increased in HCC, PC, TCC, and lymphoma. In contrast, M-MDSCs increased in the TCC. Both PMN-MDSCs and M-MDSCs exhibited immunosuppressive effects on CD8+, CD4+ and interferon-γ+ cells. In dogs with TCC, lymph node metastasis was associated with high level of PMN-MDSCs but not with M-MDSCs. High levels of both PMN-MDSCs and M-MDSCs were related to advanced tumor stage. Kaplan-Meier analysis revealed that high levels of both PMN-MDSCs and M-MDSCs were significantly associated with shorter overall survival. In addition, the Cox proportional hazard regression model showed that M-MDSCs and the tumor stage were independent prognostic factors for TCC. These results suggest that PMN-MDSCs and M-MDSCs may be involved in tumor progression and could be prognostic factors and promising therapeutic targets in dogs with TCC.

A bioassay system of autologous human endothelial, smooth muscle cells, and leukocytes for use in drug discovery, phenotyping, and tissue engineering

Blood vessels are comprised of endothelial and smooth muscle cells. Obtaining both types of cells from vessels of living donors is not possible without invasive surgery. To address this, we have devised a strategy whereby human endothelial and smooth muscle cells derived from blood progenitors from the same donor could be cultured with autologous leukocytes to generate a same donor “vessel in a dish” bioassay. Autologous sets of blood outgrowth endothelial cells (BOECs), smooth muscle cells (BO‐SMCs), and leukocytes were obtained from four donors. Cells were treated in monoculture and cumulative coculture conditions. The endothelial specific mediator endothelin‐1 along with interleukin (IL)‐6, IL‐8, tumor necrosis factor α, and interferon gamma‐induced protein 10 were measured under control culture conditions and after stimulation with cytokines. Cocultures remained viable throughout. The profile of individual mediators released from cells was consistent with what we know of endothelial and smooth muscle cells cultured from blood vessels. For the first time, we report a proof of concept study where autologous blood outgrowth “vascular” cells and leukocytes were studied alone and in coculture. This novel bioassay has usefulness in vascular biology research, patient phenotyping, drug testing, and tissue engineering.

Human airway smooth muscle cells secrete amphiregulin via bradykinin/COX-2/PGE2, inducing COX-2, CXCL8, and VEGF expression in airway epithelial cells

Human airway smooth muscle cells (HASMC) contribute to asthma pathophysiology through an increased smooth muscle mass and elevated cytokine/chemokine output. Little is known about how HASMC and the airway epithelium interact to regulate chronic airway inflammation and remodeling. Amphiregulin is a member of the family of epidermal growth factor receptor (EGFR) agonists with cell growth and proinflammatory roles and increased expression in the lungs of asthma patients. Here we show that bradykinin (BK) stimulation of HASMC increases amphiregulin secretion in a mechanism dependent on BK-induced COX-2 expression, increased PGE2 output, and the stimulation of HASMC EP2 and EP4 receptors. Conditioned medium from BK treated HASMC induced CXCL8, VEGF, and COX-2 mRNA and protein accumulation in airway epithelial cells, which were blocked by anti-amphiregulin antibodies and amphiregulin siRNA, suggesting a paracrine effect of HASMC-derived amphiregulin on airway epithelial cells. Consistent with this, recombinant amphiregulin induced CXCL8, VEGF, and COX-2 in airway epithelial cells. Finally, we found that conditioned media from amphiregulin-stimulated airway epithelial cells induced amphiregulin expression in HASMC and that this was dependent on airway epithelial cell COX-2 activity. Our study provides evidence of a dynamic axis of interaction between HASMC and epithelial cells that amplifies CXCL8, VEGF, COX-2, and amphiregulin production.

Pattern recognition receptors and interleukin-8 mediate effects of Gram-positive and Gram-negative bacteria on lung epithelial cell function

BACKGROUND AND PURPOSE

Lung epithelial cells express pattern recognition receptors, which react to bacteria. We have evaluated the effect of Gram-positive and Gram-negative bacteria on interleukin-8 (CXCL8) release from epithelial cells and the integrity of the epithelial barrier.

EXPERIMENTAL APPROACH

Primary cultures of human airway epithelial cells and the epithelial cell line A549 were used, and CXCL8 release was measured after exposure to Gram-negative or Gram-positive bacteria. Epithelial barrier function was assessed in monolayer cultures of A549 cells.

RESULTS

Gram-positive bacteria Staphylococcus aureus or Streptococcus pneumoniae, induced release of CXCL8 from human airway epithelial cells. These bacteria also disrupted barrier function in A549 cells, an effect mimicked by CXCL8 and blocked by specific binding antibodies to CXCL8. Gram-negative bacteria Escherichia coli or Pseudomonas aeruginosa induced greater release of CXCL8 than Gram-positive bacteria. However, Gram-negative bacteria did not affect epithelial barrier function directly, but prevented disruption induced by Gram-positive bacteria. These effects of Gram-negative bacteria on barrier function were mimicked by FK565, an agonist of the nucleotide-binding oligomerization domain 1 (NOD1) receptor, but not by the Toll-like receptor (TLR) 4 agonist bacterial lipopolysaccharide. Neither the Gram-negative bacteria nor FK565 blocked CXCL8 release.

CONCLUSIONS

These data show differential functional responses induced by Gram-negative and Gram-positive bacteria in human lung epithelial cells. The NOD1 receptors may have a role in preventing disruption of the epithelial barrier in lung, during inflammatory states.

NSAIDs increase GM-CSF release by human synoviocytes: comparison with nitric oxide-donating derivatives

Non-steroidal anti-inflammatory drugs (NSAIDs) are used to treat the condition of rheumatoid arthritis, where levels of prostaglandin E2 (PGE2) and granulocyte macrophage-colony stimulating factor (GM-CSF) are elevated in the synovial fluid. NO-NSAIDs are a new class of cyclooxygenase (COX)-inhibitors developed by coupling a nitric oxide (NO)-donating moiety to conventional NSAIDs. We show that, in cytokine-treated synoviocytes (from non-rheumatic patients), NO-naproxen and NO-flurbiprofen like their parent compounds concentration-dependently reduce the levels of PGE2 (an index of COX-2 activity), with a corresponding rise in the release of GM-CSF. Unlike acetylsalicylic acid (ASA), NO-ASA reduces the levels of PGE2, without increasing GM-CSF release, although cell viability is reduced at the highest concentration (1 mM). The effects of NSAIDs and NO-NSAIDs on GM-CSF release were attributable to the PGE2 mediated cyclic (c) AMP pathway because PGE2 reversed the effects of COX blockade. Second, phosphodiesterase inhibitors 3-isobutyl-1-methylxanthine (IBMX) and Ro-201724 (both of which elevate cAMP levels) decreased GM-CSF release, in the presence of PGE2. Finally, neither sodium nitroprusside nor zaprinast (both of which elevate cGMP levels) affected GM-CSF or PGE2 release. Our findings demonstrate that GM-CSF is regulated by NSAIDs and NO-NSAIDs via inhibition of COX and appears to be mediated via the cAMP pathway. NO-ASA is the exception, because it does not increase GM-CSF release, although at millimolar concentrations cell viability is reduced.

Cyclooxygenases 1, 2, and 3 and the Production of Prostaglandin I2: Investigating the Activities of Acetaminophen and Cyclooxygenase-2-Selective Inhibitors in Rat Tissues

It has been suggested recently that cyclooxygenase-3, formed as a splice variant of cyclooxygenase-1, is the enzymatic target for acetaminophen. To investigate the relative roles of the putative three cyclooxygenase isoforms in different target tissues, we compared the inhibitory effects of acetaminophen, a cyclooxygenase-2-selective inhibitor; rofecoxib, a nonsteroid anti-inflammatory drug; naproxen; and a cyclooxygenase-1-selective inhibitor, SC560 [5-(4-chlorophenyl)-1-(4-methoxyphenyl)-3-trifluoromethylpyrazole]. Prostanoid production by aorta, heart, lung, and whole blood was inhibited by all drugs tested with the order of potency SC560 > naproxen > acetaminophen >/= rofecoxib. In brain and cerebellum, no differences among drug potencies were found. Reverse transcription-polymerase chain reaction analysis of aorta, brain, cerebellum, heart, and lung showed general expression of cyclooxygenase-1 and cyclooxygenase-3 mRNA and particular expression of cyclooxygenase-2 mRNA in brain and cerebellum. Western blotting demonstrated general expression of cyclooxygenase-1 in test tissues and cyclooxygenase-2 within the brain and cerebellum. Western blotting using a commercially available antibody raised against canine cyclooxygenase-3 failed to detect any immunoreactive proteins. In conclusion, our studies indicate that cyclooxygenase-1 and cyclooxygenase-2 are the functional forms of the enzyme present in the rat tissues tested and that acetaminophen is not a selective inhibitor of "cyclooxygenase" activities in the central nervous system. This is consistent with the apparent impossibility for the expression of cyclooxygenase active protein from cyclooxygenase-3 mRNA in the rat. Also, our experiments show that the ability of rofecoxib to depress the circulating levels of prostaglandin I(2) is more readily associated with its ability to reduce production from the lung, heart, or brain than from arterial vessels.

CYTOCHROMES P450 ARE DIFFERENTLY EXPRESSED IN NORMAL AND VARICOSE HUMAN SAPHENOUS VEINS: LINKAGE WITH VARICOSIS

The expression of cytochrome P450 (CYP) enzymes and cyclo-oxygenases (COX) was investigated in human saphenous veins by reverse transcription-polymerase chain reaction analysis. Non-varicose veins were obtained from patients undergoing aortocoronary bypass grafting, whereas varicose veins were obtained from patients undergoing stripping removal of varicose saphenous veins. In non-varicose veins, CYP1B1, CYP2C, CYP2E1 and CYP4A11 were detected, whereas CYP2J2, CYP3A5, COX-1 and COX-2 were detected almost exclusively in varicose veins. CYP4F2 was not detectable. Except for CYP4A11, the levels of individual CYP mRNA were higher in varicose veins than in control veins. Smooth muscle cell volume, determined by a colour image-analysis system, was increased approximately 1.5-fold in varicose veins. Because CYPs and COXs produce various vasoactive compounds, increased expression of these enzymes could be involved in the impairment of vascular tone and may contribute to varicose pathology. Then, CYP or COX modulators may be potentially active in the treatment of chronic venous insufficiency.

15-Deoxy-Δ12,14-prostaglandin J2 inhibits the expression of granulocyte-macrophage colony-stimulating factor in endothelial cells stimulated with lipopolysaccharide

Granulocyte-macrophage colony-stimulating factor (GM-CSF), one of major hematopoietic growth factors, activates mature leukocytes. GM-CSF is produced by endothelial cells stimulated with lipopolysaccharide (LPS), and the LPS-induced GM-CSF production may play an important role in the activation of neutrophils on the endothelial surface. 15-Deoxy-delta 12,14-prostaglandin J2 (15d-PGJ2) is a ligand for peroxisome proliferator-activated receptor-gamma (PPAR-gamma) and modulates inflammatory reactions by regulating the expression of various genes. We studied the effect of 15d-PGJ2 on the LPS-induced GM-CSF expression in endothelial cells. Human umbilical vein endothelial cells (HUVEC) were cultured and the expressions of GM-CSF mRNA and protein were analyzed by reverse transcription-polymerase chain reaction and enzyme-linked immunosorbent assay, respectively. 15d-PGJ2 inhibited the LPS-induced GM-CSF expression in a concentration-dependent manner; but ciglitazone, another agonist for PPAR-gamma, had no effect. This suggests that 15d-PGJ2 inhibits GM-CSF expression through a mechanism unrelated to PPAR-gamma. 15d-PGJ2 induced, by itself, the expression of interleukin-8, a potent proinflammatory chemokine, in HUVEC. 15d-PGJ2 may regulate inflammatory reactions by controlling the balance of various cytokines.

Interleukins in atherosclerosis: molecular pathways and therapeutic potential

Interleukins are considered to be key players in the chronic vascular inflammatory response that is typical of atherosclerosis. Thus, the expression of proinflammatory interleukins and their receptors has been demonstrated in atheromatous tissue, and the serum levels of several of these cytokines have been found to be positively correlated with (coronary) arterial disease and its sequelae. In vitro studies have confirmed the involvement of various interleukins in pro-atherogenic processes, such as the up-regulation of adhesion molecules on endothelial cells, the activation of macrophages, and smooth muscle cell proliferation. Furthermore, studies in mice deficient or transgenic for specific interleukins have demonstrated that, whereas some interleukins are indeed intrinsically pro-atherogenic, others may have anti-atherogenic qualities. As the roles of individual interleukins in atherosclerosis are being uncovered, novel anti-atherogenic therapies, aimed at the modulation of interleukin function, are being explored. Several approaches have produced promising results in this respect, including the transfer of anti-inflammatory interleukins and the administration of decoys and antibodies directed against proinflammatory interleukins. The chronic nature of the disease and the generally pleiotropic effects of interleukins, however, will demand high specificity of action and/or effective targeting to prevent the emergence of adverse side effects with such treatments. This may prove to be the real challenge for the development of interleukin-based anti-atherosclerotic therapies, once the mediators and their targets have been delineated.

Modulation by colony stimulating factors of human epithelial colon cancer cell apoptosis

Colony stimulating factors (CSF) promote leukocyte survival by reducing apoptotic cell death. However, their effects on non-leukocyte cell types are unclear. Reduced apoptosis in colon epithelial cells is thought to contribute to the initiation of cancer. Here, we report diminished spontaneous apoptosis of human colon epithelial HT-29 cells in the presence of macrophage-CSF or granulocyte macrophage-CSF. Moreover, reduced apoptosis induced by sulindac sulfide was also observed with macrophage-CSF. Granulocyte-CSF failed to modify spontaneous or sulindac sulfide induced apoptosis. It seems, therefore, that the action of CSFs on apoptosis is not confined to haematopoietic cells but may be extended to stromal cells.

Cytokine modulation of granulocyte macrophage-CSF and granulocyte-CSF release from stimulated vascular smooth muscle cells

Cytokine-stimulated vascular smooth muscle cells release the colony-stimulating factors (CSFs) granulocyte macrophage-CSF and granulocyte-CSF. We have investigated the effects of a range of cytokines on the release of CSFs from human vascular smooth muscle cells stimulated with interleukin-1beta. Interleukin-4 suppressed granulocyte macrophage-CSF release but potentiated granulocyte-CSF release; interferon-gamma inhibited the release of both, whilst interleukin-5 had no effect. Both interleukin-10 and interleukin-13 inhibited granulocyte macrophage-CSF release but did not affect granulocyte-CSF release. The ability of individual cytokines to differentially modulate CSFs has profound consequences for the populations of leukocytes present at the site of inflammation.

Release of GM-CSF and G-CSF by human arterial and venous smooth muscle cells: differential regulation by COX-2

In addition to their traditional contractile function, vascular smooth muscle cells can be stimulated under inflammatory conditions to release a range of potent biological mediators. Indeed, we and others have shown that human vascular smooth muscle release the colony stimulating factors (CSF) granulocyte macrophage-CSF (GM-CSF) and granulocyte-CSF (G-CSF) as well as large amounts of prostaglandins following the induction of cyclo-oxygenase-2 (COX-2), when stimulated with cytokines. Here we demonstrate, for the first time, that co-induced COX-2 activity simultaneously suppresses GM-CSF release and potentiates G-CSF release by human vascular cells. Moreover, the differential regulation of GM-CSF and G-CSF release by COX-2 was mimicked by the prostacyclin (PGI(2)) mimetic, cicaprost. These observations suggest that PGI(2), released following the induction of COX-2, differentially regulates the release of GM-CSF (suppresses) and G-CSF (potentiates) from human vascular cells.