The effect of 3',5'-adenosine monophosphate on granulocyte adhesion

Hemocyte-hemocyte adhesion and nodulation reactions of the greater wax moth, Galleria mellonella are influenced by cholera toxin and its B-subunit

Nodulation, the lepidopteran insect immune response to large numbers of microbes in the blood (hemolymph) consists of the coordination of the blood cell (hemocyte) types the granular cells and plasmatocytes in terms of granular cell-bacteria adhesion and hemocyte-hemocyte adhesion (microaggregation). Hemocyte-microbe adhesion is influenced by the secondary messenger, cAMP, and cAMP-dependent protein kinase A. In the present study, cholera toxin, an AB5 protein known to indirectly stimulate adenylate cyclase, is used to examine the hemocyte responses to glass, bacteria and hemocyte-hemocyte microaggregates. In vitro, this toxin induces a bimodal hemocyte adhesion response that varies with the holotoxin concentration in terms of the individual and aggregated hemocyte adhesion responses: the lower CTX concentration (1.2 nM) increases microaggregate adhesion and decreases individual hemocyte binding to glass, as does higher concentrations (6-120 nM), however microaggregates induced by lower concentrations do not adhere to glass. Cholera toxin-induced microaggregation is inhibited by RGDS, suggestive of integrin involvement. In vivo, cholera toxin (1.2-120 nM) injected into larvae induces also a bimodal hemocytic response: low levels (1.2-6 nM) cause reduced hemocyte adhesion, while high levels (12-120 nM) increase hemocyte release or mobilization of adhesive hemocyte counts in the hemolymph. Increasing levels of cholera toxin concomitantly injected with the non-pathogenic bacterium, Bacillus subtilis produces a bimodal pattern in bacterial removal from the hemolymph which correlates with nodule frequency in larvae injected with cholera toxin only. The effects of higher concentrations of cholera toxin in vitro (6-120 nM) and in vivo (12-120 nM) are mediated by the B-subunit, whereas the isolated A-subunit has no effect on hemocyte activity. Cholera toxin and its individual subunits did not detectably alter levels of intracellular cAMP in the hemocytes, suggesting a cAMP-independent mechanism stimulating the nodulation response.

Production of nitric oxide by carp (Cyprinus carpio L.) kidney leukocytes is regulated by cyclic 3',5'-adenosine monophosphate

The inducible nitric oxide synthase (iNOS) plays a central role in the inflammatory reactions that follow infection or tissue damage. Induction of nitric oxide (NO) synthesis by bacterial lipopolysaccharide (LPS) depends on activation of G protein-coupled receptors in mammals. Thus, it was our intention to evaluate whether similar mechanisms are involved in iNOS activation in fish leukocytes. Therefore, the participation of membrane-bound receptors which activate effectors via G proteins has been confirmed using the G protein inhibitor suramin. Furthermore, the NO produced by iNOS performs both beneficial and detrimental actions. It is thus conceivable that regulatory mechanisms exist which control the timing and intensity of NO production by iNOS in order to outweigh protective effects against detrimental ones. The second messenger cAMP produced by adenylyl cyclases (ACs) plays a key role in the regulation of many cellular functions. Since cAMP signaling inhibits numerous immunological reactions, studies have been carried out to determine whether cAMP-dependent pathways could inhibit NO production by carp leukocytes as well. To measure cellular responses such as NO production by carp leukocytes derived from head and trunk kidneys treatments were performed with the cAMP elevating agents forskolin and dibutyryl-cAMP (db-cAMP) prior to stimulation with Aeromonas hydrophila. Pharmacological studies in stimulated kidney leukocytes showed that increased intracellular cAMP levels lead to reduced NO formation. This reduction of NO production was not due to decreased cell numbers, since a tetrazolium dye-based assay revealed no reduction of cell viability by cyclic nucleotide elevating agents. Thus, our data provide evidence that the AC/cAMP signaling pathway is well established in carp leukocytes. Cyclic AMP leads to type II immune response. We provide evidence that the predominant AC in fish leukocytes is a particulate enzyme due to its sensitivity to forskolin. Treatment of leukocytes with agents increasing intracellular cAMP gave clear evidence for participation of this cyclic nucleotide in immune signaling.

Regulation of eosinophil adhesion by lysophosphatidylcholine via a non-store-operated Ca2+ channel

We examined the mechanism by which lysophosphatidylcholine (LPC) regulates beta2-integrin-mediated adhesion of eosiniophils. Eosinophils were isolated from blood of mildly atopic volunteers by negative immunomagnetic selection. beta2-integrin-dependent adhesion of eosinophils to plated bovine serum albumin (BSA) was measured by residual eosinophil peroxidase activity. LPC caused maximal adhesion of eosinophils to plated BSA at 4 microM. Lysophosphatidylinositol, which has a similar molecular shape, mimicked the effect of LPC on eosinophil adhesion, while neither lysophosphatidylserine nor lysophosphatidylethanolamine had any effect. Phosphatidylethanolamine, a lipid that has a molecular orientation that is the inverse of LPC, blocked eosinophil adhesion caused by LPC. Unlike platelet-activating factor, a G-protein-coupled receptor agonist, LPC did not cause Ca2+-store depletion, but caused increased Ca2+ influx upon addition of Ca2+ to extracellular medium. This influx was not inhibited by U73122, a phospholipase C inhibitor, demonstrating independence from the G protein-activated phospholipase C pathway. Ca2+ influx was inhibited by either preincubation of phosphotidylethanolamine or La3+, a broad spectrum blocker of cation channels. LPC induced up-regulation of the active conformation of CD11b, which was blocked by preincubation with phosphatidylethanolamine. These data suggest that LPC causes a non-store-operated Ca2+ influx into eosinophils, which subsequently activates CD11b/CD18 to promote eosinophil adhesion.

Inhibitory effect of prostaglandin E 1 on intimal thickening caused by poor runoff conditions in the canine autologous vein grafts

The efficacy of ONO-1608, a newly developed liposomal formulation of prostaglandin E 1 prodrug, was evaluated on intimal hyperplasia of experimental canine autologous vein grafts under distal poor runoff conditions. The femoral vein was implanted into the femoral artery, preparing a distal poor runoff canine model. After 4 weeks of preparing the poor runoff model, the femoral vein was implanted into the femoral artery. They were then divided into two groups consisting of the control group and the ONO-1608 group. At 4 weeks, the grafts were harvested and intimal hyperplasia of the graft was measured with an ocular cytometer. Intimal cell proliferation was determined by bromodeoxyuridine incorporation 2 weeks after surgery. In addition, the effect of ONO-1608 on the proliferation of platelet-derived growth factor (PDGF)-stimulated human aortic smooth muscle cells (HASMCs) in culture was also investigated. At 4 weeks, the degree of intimal hyperplasia of the graft in the ONO-1608 group was significantly less than that of the control group. The bromodeoxyuridine labeling index 2 weeks after grafting was significantly lower in the ONO-1608 group compared with that in the control group. In addition, ONO-1608 significantly inhibited the proliferation of PDGF-stimulated HASMCs in culture. These results demonstrate the efficacy of ONO-1608 in reducing the degree of intimal hyperplasia of canine autogenous vein grafts under poor runoff conditions. The mechanism of reducing the intimal hyperplasia may be that ONO-1608 inhibited PDGF-stimulated proliferation of the smooth muscle cell. These results suggest that the administration of ONO-1608 may be beneficial in patients who have undergone gone arterial reconstruction.

Increased plasma free cyclic-AMP levels following major trauma and their relevance to the immune response

BACKGROUND

Following injury, neutrophil mobilisation is an important element of the immune response. The ideal features of an agent responsible for this mobilisation would include the ability to mobilise neutrophils without activating them, and rapid reversibility. This study investigates the hypothesis that raised levels of plasma adrenaline following trauma act via cyclic adenosine monophosphate (cAMP) to mobilise neutrophils, and measures the amount of cAMP extruded from cells into the plasma following injury.

METHODS

20-ml samples of venous blood were drawn from 34 trauma patients within 3 h of injury and divided between three sample tubes: (1) ethylene diamine tetra-acetic acid anticoagulant (EDTA) for full blood count; (2) cooled EDTA for cAMP levels; and (3) cooled lithium heparin for catecholamines. The latter two tubes were immediately centrifuged at low temperature and the supernatant plasma deep frozen pending analysis. Adrenaline was measured using high pressure liquid chromatography (HPLC) and cAMP measured by an enzyme immunoassay technique.

RESULTS

34 patients, six of whom had sustained minor trauma (ISS 1-8), 12 moderate trauma (ISS 9-15) and 16, major trauma (ISS 16 and above) were studied. Median age was 39 years (range 16-77) and 30 patients were male. Plasma adrenaline levels were available for 28 of the patients. Plasma free cAMP levels were significantly raised in patients with major trauma (P < 0.006). There were positive correlations between the plasma levels of cAMP and adrenaline (rho 0.660, P = 0.011), adrenaline and neutrophil count (rho 0.654, P = 0.01) and cAMP and neutrophil count (rho 0.508, P = 0.013).

CONCLUSIONS

Evidence is presented of the possible inter-relationships between neutrophil counts, adrenaline levels and cAMP levels following injury, supporting the proposition that neutrophil mobilisation pathways are activated early via beta-adrenergic stimulation.

Superior protection in orthotopic rat lung transplantation with cyclic adenosine monophosphate and nitroglycerin-containing preservation solution

BACKGROUND

Primary lung graft failure is common, and current lung preservation strategies are suboptimal. Because the decline in lung levels of cyclic adenosine monophosphate and cyclic guanosine monophosphate during preservation could enhance adhesiveness of endothelial cells for leukocytes as well as increase vascular permeability and vasoconstriction, we hypothesized that buttressing these levels by means of a preservation solution would significantly improve lung preservation.

METHODS

An orthotopic rat left lung transplantation model was used. Lungs were harvested from male Lewis rats and preserved for 6 hours at 4 degrees C with (1) Euro-Collins solution (n = 8); (2) University of Wisconsin solution (n = 8); (3) low-potassium dextran glucose solution (n = 8); (4) Columbia University solution (n = 8), which contains a cyclic adenosine monophosphate analog (dibutyryl cyclic adenosine monophosphate) and a nitric oxide donor (nitroglycerin) to buttress cyclic guanosine monophosphate levels; or (5) Columbia University solution without cyclic adenosine monophosphate or nitroglycerin (n = 8). PaO2, pulmonary vascular resistance, and recipient survival were evaluated 30 minutes after left lung transplantation and removal of the nontransplanted right lung from the pulmonary circulation.

RESULTS

Among all groups studied, grafts stored with Columbia University solution demonstrated the highest Pa O2 (355 +/- 25 mm Hg for Columbia University solution versus 95 +/- 22 mm Hg for Euro-Collins solution, P <.01, 172 +/- 55 mm Hg for University of Wisconsin solution, P <.05, 76 +/- 15 mm Hg for low-potassium dextran glucose solution, P <.01, and 82 +/- 25 mm Hg for Columbia University solution without cyclic adenosine monophosphate or nitroglycerin, P <.01) and the lowest pulmonary vascular resistances (1 +/- 0.2 mm Hg * mL-1 * min-1 for Columbia University solution versus 12 +/- 4 mm Hg * mL-1 * min-1 for Euro-Collins solution, P <.01, 9 +/- 2 mm Hg * mL-1 * min-1 for University of Wisconsin solution, 14 +/- 6 mm Hg * mL-1 * min-1 for low-potassium dextran glucose solution, P <.01, and 8 +/- 2 mm Hg * mL-1 * min-1 for Columbia University solution without cyclic adenosine monophosphate and nitroglycerin). These functional and hemodynamic improvements provided by Columbia University solution were accompanied by decreased graft leukostasis and decreased recipient tumor necrosis factor alpha and interleukin 1alpha levels compared with the other groups. In toto, these improvements translated into superior survival among recipients of Columbia University solution-preserved grafts (100% for Columbia University solution, 37% for Euro-Collins solution, P <.01, 50% for University of Wisconsin solution, P <.05, 50% for low-potassium dextran glucose solution, P <.05, and 13% for Columbia University solution without cyclic adenosine monophosphate and nitroglycerin, P <.01).

CONCLUSION

Nitroglycerin and cyclic adenosine monophosphate confer beneficial vascular effects that make Columbia University solution a superior lung preservation solution in a stringent rat lung transplantation model.

Theophylline accelerates human granulocyte apoptosis not via phosphodiesterase inhibition

Theophylline, in addition to its bronchodilator effect, is reported to have an antiinflammatory action that may account for its clinical effectiveness in the reduction of inflammatory cells in the airway. In bronchial asthma, such inflammatory cytokines as GM-CSF and IL-5 are upregulated and have been proposed to cause granulocyte infiltration (neutrophils and eosinophils) in the airway by inhibition of granulocyte apoptosis. We examined the abilities of theophylline to counteract the prolongation of human granulocyte survival caused by cytokines. Theophylline was shown to shorten granulocyte survival in a dose-dependent manner. Upon incubation with a therapeutical concentration of theophylline (0.1 mM; 18 microg/ml), percentages of GM-CSF (10 ng/ml)-induced delayed apoptosis increased from 18+/-2% to 38+/-3% (p < 0.02) in neutrophils and from 21+/-2% to 35+/-2% (p < 0.02; 24-h incubation) in eosinophils. The percentage of IL-5 (5 ng/ml)-induced delayed eosinophil apoptosis also increased from 22+/-4% to 33+/-2% (P < 0. 05). In contrast, cyclic AMP (cAMP)-increasing agents (3-isobutylmethylxanthine, dibutyryl cAMP, and rolipram) inhibited granulocyte apoptosis in the control and anti-Fas antibody-treated cells. In eosinophils, the expression of bcl-2 protein decreased after incubation with theophylline. These findings suggest that theophylline accelerates granulocyte apoptosis, which may play an essential role in inflammation, and controls granulocyte longevity regardless of the elevation of intracellular cAMP levels.

Inhibitory effect of prostaglandin E1 on intimal thickening following photochemically induced endothelial injury in the rat femoral artery

The inhibitory effect of prostaglandin E1, which has an anti-platelet action and a vasodilating action via intracellular cyclic AMP elevation, was studied on intimal thickening in the rat femoral artery. A segment of the femoral artery was occluded by a platelet and fibrin-rich thrombus due to photochemical reaction between systemically administered Rose Bengal and transluminal green light which causes endothelial injury followed by platelet adhesion and aggregation at the site of photochemical reaction. Three weeks after endothelial injury, intimal thickening occurred at the irradiated site. Prostaglandin E1 (0.3 microgram/kg per min), administered as a continuous infusion 10 min before photochemical reaction significantly (P < 0.05) prolonged the time to occlusion of the femoral artery. In a separate experiment, prostaglandin E1 (0.3 microgram/kg per min) administered as a continuous infusion for 7 days just after endothelial injury significantly (P < 0.05) inhibited intimal thickening compared with a control group. In cultured rat-derived vascular smooth muscle cells, prostaglandin E1 produced concentration-dependent inhibition of migration and proliferation, stimulated by platelet-derived growth factor. These results suggest that prostaglandin E1 may be effective in preventing vascular restenosis after vascular surgery and angioplasty.

cAMP-mediated vascular protection in an orthotopic rat lung transplant model. Insights into the mechanism of action of prostaglandin E1 to improve lung preservation

Prostaglandin E1 (PGE1) is often added to the donor pulmonary flush solution to enhance clinical lung preservation for transplantation. Although PGE1 is thought to act as a pulmonary vasodilator during the harvest period, the precise mechanism(s) of action whereby PGE1 enhances lung preservation is unknown. Because cAMP levels decline in endothelial and vascular smooth muscle cells exposed to hypoxia, we hypothesized that a PGE1-mediated increase in cAMP levels within the preserved lungs might improve pulmonary vascular homeostasis following lung transplantation. Rat lungs demonstrated a time-dependent decline in cAMP levels during hypothermic storage, with cAMP levels significantly increased by PGE1 supplementation (approximately 2-fold by 6 hours, P < .0005). To test whether augmenting cAMP levels may enhance lung preservation, experiments were performed using an orthotopic rat left lung transplant model. Compared with controls, supplementing the preservation solution with the membrane-permeable cAMP analogue dibutyryl-cAMP resulted in dose-dependent preservation enhancement, marked by reduced pulmonary vascular resistance (6.0-fold, P < .01), improved arterial oxygenation (3.0-fold, P < .01), reduced graft neutrophil infiltration (1.5-fold, P < .05), and improved recipient survival (7.0-fold, P < .005). Similar preservation enhancement was observed with another cAMP analogue (8-bromo-cAMP) or the phosphodiesterase inhibitor indolidan. Stimulating the cAMP second messenger system by PGE1 supplementation resulted in marked hemodynamic benefits and improved recipient survival, in parallel with reduced graft neutrophil infiltration, vascular permeability, and platelet deposition. These beneficial effects of PGE1 were abrogated by simultaneous administration of the cAMP-dependent protein kinase antagonist Rp-cAMPS. Although an arterial vasodilator (minoxidil) resulted in significant pulmonary vasodilation during harvest, it lacked other nonvasodilating effects of PGE1 and resulted in poor preservation. These data show that harvest vasodilation by itself is insufficient to enhance lung preservation and that PGE1 enhances lung preservation by stimulating the cAMP-dependent protein kinase and promoting non-vasodilatory mechanisms of pulmonary protection.

Iloprost inhibits neutrophil-induced lung injury and neutrophil adherence to endothelial monolayers

We hypothesized that Iloprost, a long-acting prostacyclin analog, would inhibit neutrophil (PMN)-induced lung injury and decrease PMN adherence to vascular endothelium. Human PMNs infused into isolated buffer-perfused rat lungs subsequently stimulated with phorbol myristate acetate (PMA) resulted in lung injury as assessed by the accumulation of [125I]bovine serum albumin (125I-BSA) in lung parenchyma and alveolar lavage fluid. Addition of Iloprost to the lung perfusate, prior to activation of the PMNs, reduced lung injury as assessed by a decrease in the accumulation of 125I-BSA in the lung. This protective effect was not due to the vasodilatory effect of Iloprost. Protection by Iloprost was not linked to a reduction in PMA-induced PMN superoxide production since Iloprost did not reduce the amount of superoxide released into lung perfusate. In vitro, Iloprost caused a dose-dependent inhibition of PMA-stimulated PMN adherence to endothelial cells. Iloprost did not affect the number of Mo1 adhesion molecules constitutively expressed or the number of receptors expressed on the PMNs following PMA. Addition of cAMP or dibutyryl cAMP to the endothelial cells mimicked the effects of Iloprost, diminishing PMA-stimulated PMN adhesion. In separate experiments, addition of the phosphodiesterase inhibitor IBMX to Iloprost resulted in a greater inhibition of PMA-stimulated PMN adherence, while addition of an adenylate cyclase inhibitor, SQ 22,536, or cAMP antibodies with the Iloprost abolished Iloprost's inhibitory effect on PMN adhesion. Thus, Iloprost inhibits PMA-activated PMN-induced lung injury despite continued superoxide production. Iloprost inhibition of PMN adhesion is dependent on cAMP.

Leukocyte adhesion molecules deficiency: its structural basis, pathophysiology and implications for modulating the inflammatory response

Understanding the molecular basis of a rare inherited disease, Leu-CAM deficiency in humans, has underscored the importance of the cellular component of inflammation and unravelled the complex series of homotypic and heterotypic cell interactions necessary for mobilization of leukocytes to infected sites. Furthermore, this disease has shown that several apparently distinct cellular inflammatory responses (e.g. aggregation, adhesion to endothelium, directed migration and phagocytosis) are mechanistically related and mediated by a set of molecules which belong to a larger group of adhesion molecules (Integrins) mediating similar phenomena critical for immune surveillance, lymphocyte homing, morphogenesis and thrombogenesis. This disease also showed the relative biologic importance of CD11/CD18 in leukocytes. CD11/CD18 are more critical for the functions of phagocytic cells as compared to lymphocytes although similar inhibitory effects of anti-CD11/CD18 mAbs can be demonstrated in vitro. Expression and function of CD11/CD18 is regulated at several levels which include formation of stable heterodimers, qualitative changes in the receptor and quantitative changes in the levels of expression of the receptors and their ligands. We have identified inherited single amino acid substitutions on CD18 which impair heterodimer formation and cell surface expression, thus accounting for the pathogenesis of Leu-CAM deficiency. We also found a stimulus-induced phosphorylation of CD18, which is transient in nature when elicited through other surface receptors. This may be important in regulation of CD11/CD18 receptor avidity, recycling, endocytosis and cross-talk with other receptors. Finally, realization of the profound impairment in the acute cellular inflammatory response present in Leu-CAM deficiency has permitted novel ways of controlling the inflammatory response in several situations were inflammation serves an injurious rather than a beneficial role to the host.

Comparative studies on the adhesiveness of granulocytes of guinea pig and man

The high affinity of granulocytes of guinea pig and man to glass surfaces is modified by serum. Native serum contains both an adherence-promoting activity, which is related to complement, and components which reduce the adhesiveness of granulocytes. These components are stable at 56 degrees C for 30 min and are tightly bound to the glass surface. beta-Lipoproteins are candidates for this adherence reducing ability of serum. Adherence promotion by native serum is mediated by coating the glass surface with C3b/C3bi. Human granulocytes from the peripheral blood adhered pig serum with C3b/C3bi to almost the same extent as in the presence of native serum, but on guinea pig granulocytes elicited in the peritoneal cavity, a cell surface metalloproteinase degraded the C3b/C3bi, thus reducing the adhesiveness of these cells. This proteinase was inhibited by MgEDTA, DTT, and 1,10-phenanthroline, whereby the high adhesiveness of granulocytes was restored to C3b/C3bi-coated glass.

PGE1 inhibits neutrophil adherence and neutrophil-mediated injury to cultured endothelial cells

Prostaglandin E1 (PGE1) has been shown to inhibit acute inflammatory reactions involving vascular permeability changes and subsequent tissue damage caused by immune complex deposition and other inflammatory mediators. These effects have been postulated to be due to functional changes induced in circulating neutrophils by PGE1. We evaluated the ability of PGE1 (1 to 100 microM) to protect endothelial cells (EC) from neutrophil injury induced by C5a or phorbol myristate acetate (PMA). The injury to endothelial monolayers was quantitated by 51Cr loss after an 18-h incubation. In the presence of PGE1, there was a concentration-dependent inhibition of C5a- or PMA-stimulated human neutrophil injury to EC. The protective effect was more effective by pretreatment of neutrophils than EC. Since neutrophil adherence to endothelial cells is thought to be an early event in the sequence resulting in injury to vascular endothelium, we next evaluated the effect of PGE1 on neutrophil adherence to plastic surfaces and EC. In a similar fashion, there was a concentration-dependent inhibition of neutrophil adherence to plastic and EC following stimulation with PMA (10 ng/ml), human C5a (5 micrograms/ml) or formyl-met-leu-phe (FMLP, 2 x 10(-7) M). To investigate a possible mechanism of inhibition of neutrophil adherence to plastic surfaces or EC, expression of the neutrophil surface protein Mo1, previously shown to be associated with increased granulocyte adherence, was measured by fluorescence flow cytometry. Although basal levels of Mo1 expression by unstimulated neutrophils were diminished by PGE1 treatment, there was no significant inhibition of PMA- or FMLP-stimulated Mo1 expression in PGE1-treated neutrophils compared with neutrophils stimulated in the absence of PGE1.(ABSTRACT TRUNCATED AT 250 WORDS)

A comparison of the free radical scavenging activity of leukotrienes and prostaglandins

The relative reactivity of leukotrienes and prostaglandins to free radicals and the superoxide ion generated by the photo oxidation of dianisidine have been assessed in vitro. Leukotrienes are effective general radical scavengers rather than superoxide scavengers, with the order of effectiveness LTD4 greater than LTC4 greater than LTB4. Prostaglandins are relatively unreactive. It is suggested that this susceptibility to free radical attack may be one reason for the formation of chemotactic agents from leukotrienes rather than prostaglandins and this may be one part of the mode of action of these compounds in chronic inflammation.

A method for the determination of the adherence of granulocytes to microtitre plates

We report a new partially automated method for the measurement of the adherence of PMN in vitro. Adherence to a plastic surface was detected by measuring leukocyte alkaline phosphatase activity of the adherent cells, with a Titertek Multiscan system. Using three different cellular concentrations (1 X 10(6), 5 X 10(5), 2.5 X 10(5) PMN/ml) the response curve was linear to 45 min and adhesion was maximal by 30 min. The specificity of the reaction was acceptable as was the assay reproducibility (intra-assay coefficient of variation less than 8%; inter-assay coefficient of variation less than 11%).

In vitro effects of prostaglandin E1, prostaglandin E2, indomethacin, histamine, and tuftsin on chemiluminescence response of bovine polymorphonuclear leukocytes

The in vitro effects of prostaglandin E1 (PGE1), prostaglandin E2 (PGE2), indomethacin, histamine, and tuftsin on the chemiluminescence response of bovine polymorphonuclear cells (PMN) were determined. Addition of PGE1, PGE2, indomethacin, and histamine in vitro significantly suppressed the chemiluminescence response of bovine PMN's, whereas tuftsin had no effect. Suppression was dependent upon the continued presence of PGE1, PGE2, and histamine in the culture media. However, indomethacin's suppressive effect remained even after it was removed from the culture media. Hydrogen peroxide generated chemiluminescence was suppressed by high concentrations of indomethacin and histamine. Results of this study suggest possible pharmacologic or regulatory mechanisms for certain of these immune modulators in the control of the oxidative burst reaction of bovine PMN's.

The effects of histamine and serotonin on polymorphonuclear leukocyte accumulation in the rat

Histamine and serotonin were evaluated for their effects on rat polymorphonuclear leukocyte (PMN) accumulation in vivo and PMN migration in vitro. Both of the mediators inhibited the accumulation of PMNs when injected into the pleural cavity in a saline vehicle, and reduced the PMN content of the peripheral blood. Histamine also reduced the cellular influx when administered in combination with an intrapleural injection of carrageenan. Peripheral blood leukocytes removed from rats injected intrapleurally with histamine and carrageenan had a lesser chemotactic responsiveness compared with those removed from rats injected only with carrageenan. The effects of histamine in reducing PMN accumulation was abolished by treatment with cimetidine, an H2 antagonist, but not by treatment with chlorpheniramine, an H1 antagonist. These results suggest that a local release of histamine may play a role in reducing cellular infiltration into an inflammatory site.

Inhibition by prostaglandins of leukotriene B4 release from activated neutrophils

Chemoattractant N-formylmethionylleucylphenylalanine (fMet-Leu-Phe) in the presence of cytochalasin B stimulates the release of leukotriene B4 (LTB4), superoxide (O2-), and N-acetylglucosaminidase from elicited rat peritoneal and human peripheral neutrophils [PMN (polymorphonuclear leukocytes)]. Prostaglandins E1 and E2 (PGE1 and PGE2) inhibit LTB4 release from PMN in a dose-related manner with an IC50 of 1 X 10(-8) M. This action is associated with increased levels of cyclic AMP. The inhibitory activity of a variety of PGs on LTB4 production by rat peritoneal PMN parallels their affinity for PGE receptors in other tissues. O2- release is also suppressed by low levels of PGE1 and PGE2 in a dose-related manner and this inhibition is enhanced by theophylline. In contrast, lysosomal enzyme release is only minimally affected by physiological levels of PGs. These data are consistent with an action of PGs at the level of the PG receptor on LTB4 and O2- release from the fMet-Leu-Phe-stimulated rat peritoneal PMN. In addition, the fMet-Leu-Phe-induced adherence of PMN to endothelial cells and inhibition of this phenomenon by PGs may now be explained by PG-mediated inhibition of LTB4 formation.

Enhancement of granulocyte-endothelial cell adherence and granulocyte-induced cytotoxicity by platelet release products

Complement-stimulated granulocytes adhere to and induce significant 51Cr release from endothelial cells in vitro. Platelets were stimulated to undergo release, and these release products significantly enhanced granulocyte-endothelial cell adherence and granulocyte-induced 51Cr release from endothelial cells. Platelet serotonin appeared to mediate these phenomena because serotonin antagonists blocked both the enhanced endothelial adherence and 51Cr release. In addition, added serotonin mimicked the effect seen with the stimulated platelets upon granulocyte--endothelial cell adherence and cytotoxicity completely. This enhancement appeared to be due to serotonin effects upon both the granulocyte and endothelial cells. These data suggest that a released platelet constituent might modulate in vivo granulocyte-endothelial cell interactions in clinical disorders.

Thromboxane A2 mediates augmented polymorphonuclear leukocyte adhesiveness

We examined the role of prostaglandins and thromboxanes as mediators of plasma-dependent increased polymorphonuclear leukocyte adhesiveness induced by Escherichia coli lipopolysaccharide. The cyclo-oxygenase inhibitors-indomethacin and d,l-6-chloro-alpha-methyl-carbozole-2-acetic acid (R020-5720)-reduced lipopolysaccharide-induced adherence of polymorphonuclear leukocytes by 74 and 62%, respectively. In addition, inhibitors of thromboxane synthetase-imidazole, 9,11-azoprosta-5,13-dienoic acid, and 1-benzylimidazole-suppressed the stimulation of adherence by 31, 66, and 83%, respectively. Exogenous prostaglandins E(1), E(2), and F(2)alpha did not increase polymorphonuclear leukocyte adherence, nor were they detected in significant quantities in supernates of polymorphonuclear leukocytes exposed to lipopolysaccharide. However, inhibitors of both cyclo-oxygenase and thromboxane synthetase reduced increases in adherence induced by arachidonic acid (10 mug/ml), suggesting that lipopolysaccharide-mediated increases in adherence were due to an arachidonic acid product other than prostaglandin E(2) or F(2)alpha. 8,11,14-Eicosatrienoic acid, a precursor of monoenoic prostaglandins, did not enhance polymorphonuclear leukocyte adhesiveness. We next demonstrated lipopolysaccharide-stimulated generation, by polymorphonuclear leukocytes, of a labile, low molecular weight, dialyzable substance capable of enhancing the adherence of unstimulated leukocytes. In parallel experiments, a 10-fold increase in immunoreactive thromboxane B(2) over basal levels was detected after exposure of leukocytes to lipopolysaccharide. The inhibition of lipopolysaccharide enhancement of adherence by specific rabbit antibodies to thromboxane B(2) strongly supported a primary role for thromboxane A(2) as the mediator of the observed increases in adherence. Lipopolysaccharide-stimulated purified platelets did not increase leukocyte adherence, whereas thrombin-stimulated platelets did increase adherence. These studies suggest that lipopolysaccharide stimulates polymorphonuclear leukocytes to produce thromboxane A(2), which enhances their adhesiveness to nylon.

The evaluation of selected parameters of immune function in asthmatics after long-term corticosteroid therapy

The availability of inhaled beclomethasone diproprionate permitted the discontinuation of continuous, long-term systemic corticosteroid therapy (SCT) in a group of asthmatics who had previously required SCT to control their asthma. Twelve patients had been on SCT for a period of 2-22 years with an average duration of 7 years. To determine whether this previous long-term SCT and the current use of inhaled beclomethasone diproprionate had an effect on leucocyte functions, a variety of studies reflecting T lymphocyte, B lymphocyte and granulocyte function was done. The results were compared with those of twelve asthmatic patients of similar age ranges who had never received steroids. Results showed that the two patient populations could not be differentiated on the basis of phytohaemagglutinin stimulation of lymphocytes, sheep erythrocyte rosette formation, IgG, IgA, IgM and IgE concentrations or granulocyte bactericidal activity. Delayed skin reactivity was present in both groups, with more positive reactions in the non-SCT group. Polymorphonuclear adherence values were slightly lower in the SCT female population using beclomethasone diproprionate. The latter two minor differences may be due to the previous SCT, the use of beclomethasone diproprionate or the limited population of patients studied. We conclude from these studies that the long-term use of SCT at the low doses required for control of asthma resulted in little permanent effect on the variety of lymphocyte and granulocyte functions tested.

Motility and adhesiveness in human neutrophils. Effects of chemotactic factors

Human peripheral blood neutrophils (PMN) obtained from healthy adults were examined in vitro with techniques adapted to assess the effects of chemotactic factors (CF) on cellular configuration and adhesiveness. The results were compared with those that use certain conventional techniques for assessing chemotaxis and chemokinesis. Exposure of PMN to N-formyl-l-methionyl-l-phenylalanine (f-Met-Phe), zymosan-activated serum, bacterial chemotactic factor, or a low molecular weight chemotactic factor from activated serum (C5a) in the absence of a gradient resulted in a change in cellular shape from a spherical to a polarized configuration in a high percentage of cells. This occurred rapidly in suspension, under conditions designed to exclude a role for cell adhesiveness, and was reversible upon removal of the CF. Restimulation of cells with the CF resulted in reappearance of the polarized configuration to the same extent as on initial stimulation with one exception: f-Met-Phe pretreated cells failed to respond to f-Met-Phe, though they responded fully to the other CF. Each CF caused a significant increase in PMN attachment to protein-coated glass. This enhanced adhesiveness was not reversible upon removal of the CF when the cells were treated under conditions shown to produce chemotactic deactivation. Cells treated under these conditions also exhibited significantly reduced motility on glass and in micropore filters in the absence of a gradient of CF. Bacterial chemotactic factor, even at high concentrations, failed to produce deactivation and did not cause a sustained enhancement of adhesiveness.

The role of locomotion in lymphocyte migration

In this study, the role of cell locomotion in lymphocyte traffic was investigated following the in vivo fate of 51Cr labelled lymph node cells pretreated in vitro with substances known to modify cell motility. The results obtained show that lymphocyte migration is an energy dependent process, as it could be impaired by sodium azide. That it requires the integrity of microfilaments, as it was modified by Cytochalasin B; and that it is altered by isoproterenol, theophylline, prostaglandin E1 and dibutyryl cyclic-AMP. The relevance of these findings to the process of lymphocyte recirculation is discussed.

Propranolol antagonizes the anti-inflammatory effect of alcohol and improves survival of infected intoxicated rabbits

We studied the effects of alcohol and propranolol on the course of peritonitis in rabbits. Induction of sterile peritonitis with normal saline led to a 50% augmentation of granulocyte adherence in normal rabbits, and a mean cumulative granulocyte count of 27,000/mm(3) in peritoneal exudate by 8 h. Rabbits intoxicated with alcohol at the time of peritonitis induction maintained a granulocyte adherence below pretreatment values, and only delivered a cumulative mean of 12,000 granulocytes/mm(3) into the peritoneal fluid. When intoxicated rabbits received propranolol intravenously at the time of intoxication, adherence increased above preperitonitis levels, and stayed significantly above values for animals given alcohol alone. In addition, the defect in granulocyte delivery was prevented by propranolol, resulting in a mean cumulative granulocyte count in peritoneal fluid of 24,000/mm(3).When peritonitis was induced with live pneumococci instead of a sterile inflammatory stimulus, 14/18 normal animals survived the infection and were culture-negative when sacrificed at 2 wk. In contrast, 17/18 intoxicated animals died of the infection, in a mean of 2.8 days. 9 of 18 intoxicated animals who also received propranolol survived, and those who died lived a mean of 7.5 days. The survival rates and the time-to-death among the nonsurvivors given propranolol were both significantly greater than in the animals intoxicated without propranolol. Thus, propranolol prevents the granulocyte adherence and delivery defects induced by alcohol intoxication, and significantly improves survival from infection.

The neutrophil adherence assay as a method for detecting unique anti-inflammatory agents

Neutrophil adhesiveness is an important component of the pathophysiology of the inflammatory process. Modulation of this function could result in a reduction in the degree of inflammation and connective tissue damage. A simple technique using filtration of whole blood through nylon fiber columns has been developed to study the effect of anti-inflammatory agents on the adherence of rat peripheral blood neutrophils. Gold and chloroquine, in addition to many standard anti-inflammatory drugs, have been shown to cause inhibition of neutrophil adherence. Measurement of this parameter of cell behavior has the potential of detecting anti-inflammatory agents not normally effective in the standard animal models.

Thyrotropin-specific binding to human peripheral blood monocytes and polymorphonuclear leukocytes

[125I]Labeled thyrotropin binding to leukocytes has been studied using lymphocyte-, monocyte- and polymorphonuclear leukocytes-enriched preparations obtained by centrifugation of Ficoll-Angiocontrix gradients and Sephadex G-10 adherence. From the relation between thyrotropin binding and phagocytosis as shown by latex beads ingestion, it is concluded that the hormone binds essentially to monocytes and polymorphonuclear leukocytes. Equilibrium association constants of the high-affinity, low-capacity sites (1 nM-1) are similar to those found in isolated thyroid cells or in thyroid plasma membranes. The role of thyrotropin in the regulation of phagocytosis by leukocytes is discussed.

Mechanism of anti-inflammatory action of glucocorticosteroids

Glucocorticosteroids react with blood monocytes and tissue macrophages to produce a peptide factor which stimulates the random migration of polymorphs in vitro in the capillary-tube migration system. An identical effect on polymorph migration is produced by colchicine and vinblastine, drugs which inhibit the assembly of the cytoplasmic microtubules on which the functional activity of polymorphs depends. Pharmacological agents which inhibit microtubular assembly indirectly by increasing intracellular cyclic adenosine monophosphate (A.M.P.), also stimulate polymorph migration in vitro. These observations suggest that the anti-inflammatory activity of glucocorticosteroid drugs is mediated by a peptide hormone which inhibits polymorph microtubular assembly. Many peptide hormones are believed to act by increasing the concentration of cyclic A.M.P. within target cells and this mechanism is probably also responsible for the inhibitory effect of steroids on phagocytic cells.

The effect of anti-inflammatory agents and inflammation on granulocyte adherence. Evidence for regulation by plasma factors

Significant inhibition of granulocyte adherence to nylon fiber columns followed the administration of alcohol, aspirin, sodium salicylate, acetaminophen, indomethacin, phenylbutazone, colchicine or prednisone to normal subjects. The addition of salicylates and glucocorticoids to blood in vitro had no effect on adherence, but plasma from volunteer subjects treated with either drug contained a factor which inhibited the adherence of normal granulocytes. The factor is heat stable, nondialyzable and not present in serum; it produces a linear dose response in normal cells. When mixed with the adherence-increasing factor found in inflammatory diseases, it neutralizes the augmenting effect and normal granulocyte adherence results. The effect of anti-inflammatory therapy on inflammatory disease was studied in aspirin-treated patients with rheumatoid arthritis. Their granulocyte adherence fell into two categories based on the clinical control of their disease; patients in good control had only slightly increased granulocyte adherence, but those in poor control had an average adherence more than twice normal. Mean blood aspirin levels were equivalent for the two groups (11.0 mg/100 ml for the well controlled and 13.4 mg/100 ml for those poorly controlled). Thus, clinical response to anti-inflammatory therapy correlates well with granulocyte adherence, not with aspirin levels. The potential pathogenetic role of adherence-modifying factors in inflammatory diseases remains to be determined.

The effects of cyclic AMP on leucocyte inhibitory factor (LIF) production and on the inhibition of leucocyte migration

The effect of drugs known to increase intracellular levels of cyllic AMP were studied in the leucocyte migration ihibition system. It was found that cyclic AMP, dibutyryl cyclic AMP, theophyline, and prostaglandins E1 and E2 inhibited the production of leucocyte inhibiting factor by HA pulsed lymphocytes Inhibition only occured when the drugs were present during or after the PHA pulse. In addition it was found that these drugs enhanced the migration of polymorphonuclear leucocytes (PMN), in this system. Electrophoretic mobility of PMN cells was not altered by these drug indicating that the effect is not due to changes in membrane charge. However, granulocyte adhesion was reduced in the presence of these drug suggesting that adhesion is of primary importance in the migration of polymorphonuclear leucocytes out of capillary tubes. The findings show that cyclic AMP is important in modulating both cell-mediated and inflammatory responses.