The effect of hydrocortisone on superoxide production by leukocytes

The airway epithelium: more than just a structural barrier

The mammalian airway is lined by a variety of specialized epithelial cells that not only serve as a physical barrier but also respond to environment-induced damage through the release of biologically active factors and constant cellular renewal. The lung epithelium responds to environmental insults such as pathogens, cigarette smoke and pollution by secreting inflammatory mediators and antimicrobial peptides, and by recruiting immune cells to the site of infection or damage. When the epithelium is severely damaged, basal cells and Clara cells that have stem-cell-like properties are capable of self-renewal and proliferation in the affected area, to repair the damage. In order to effectively fight off infections, the epithelium requires the assistance of neutrophils recruited from the peripheral circulation through transendothelial followed by transepithelial migration events. Activated neutrophils migrate across the epithelium through a series of ligand-receptor interactions to the site of injury, where they secrete proteolytic enzymes and oxidative radicals for pathogen destruction. However, chronic activation and recruitment of neutrophils in airway diseases such as chronic obstructive pulmonary disease and asthma has been associated with tissue damage and disease severity. In this paper, we review the current understanding of the airway epithelial response to injury and its interaction with inflammatory cells, in particular the neutrophil.

Inhibitory capacity of different steroids on neutrophil migration across a bilayer of endothelial and bronchial epithelial cells

Neutrophil infiltration to the airway lumen is a common feature of respiratory inflammatory processes. The aim of this study was to evaluate whether different corticosteroids exert any selective effect on the migration of isolated neutrophils. A bilayer of cultured human endothelial and bronchial epithelial cells was used as a model for neutrophil migration through the blood-air barrier. Low spontaneous migration of neutrophils (2.8+/-0.9%, n=8; mean+/-S.E.M.) occurred, while in the absence of any steroid, a migration of 28.5+/-7.6% could be induced by lipopolysaccharide. Pre-incubation during 1 h of epithelial cells with dexamethasone, budesonide, or prednisolone (10(-10)-10(-4) M) showed in all instances a concentration-dependent inhibition following a bell-shaped curve. At 10(-7) M, both dexamethasone and budesonide were on the minimum effect peak of the bell-shaped curve. The peak for prednisolone was found at 10(-8) M. However, when steroid pre-incubation was extended to 4 h, a sigmoid curve was observed, with significant inhibition of migration at concentrations >10(-7) M. Steroids can inhibit neutrophil recruitment through two different pathways with distinct result, depending on the length of incubation time.

Endogenous glucocorticoids modulate neutrophil migration and synovial P-selectin but not neutrophil phagocytic or oxidative function in experimental arthritis

Pharmacologic glucocorticoids are powerful inhibitors of the inflammatory response at many levels, including leucocyte trafficking and function. The adhesion molecule P-selectin is a key participant in polymorphonuclear neutrophil (PMN) migration to sites of inflammation. The extent to which endogenous glucocorticoids influence PMN migration and activation is not clear. We used the glucocorticoid receptor antagonist RU486 to examine the effect of endogenous glucocorticoid blockade on PMN migration and function in carrageenan monoarthritis in the rat. Arthritis was induced by intraarticular injection of carrageenan and disease severity measured by PMN count in synovial lavage fluid. Decalcified frozen sections of injected joints were analysed for expression of P-selectin by immunohistochemistry. Adrenal glucocorticoid action was blocked in vivo with RU486 20 mg/kg. PMN phagocytosis and reactive oxygen species synthesis were measured by flow cytometry. Carrageenan injection was associated with severe arthritis (synovial lavage PMN 5.9 +/- 0.7 x 10(6), P < 0.01 versus control) which was dose-dependent. P-selectin was not detected in normal joints but was abundant in joints injected with 500 microg carrageenan. RU486 resulted in exacerbation of carrageenan arthritis (9.7 +/- 0.8 x 10(6), P < 0.05). RU486 also altered the threshold for disease induction, in that most RU486-treated animals were susceptible to arthritis at a dose of carrageenan (2.5 microg) which did not induce arthritis in most control-treated animals (P < 0.05), denoting an altered threshold for arthritis induction. RU486 treatment was associated with increased synovial P-selectin expression. Activation status as measured by PMN phagocytic and oxidative function were not influenced by endogenous glucocorticoid blockade. These findings suggest that endogenous glucocorticoids selectively influence PMN migration to inflamed joints via P-selectin expression, but have no effect on PMN activation status.

Effect of in vivo corticosterone and acute food deprivation on rat resident peritoneal cell chemiluminescence after activation ex vivo

Adrenoglucocorticoid regulation of rat peritoneal monocyte/macrophage function was studied by exposing rats to corticosterone (CS) in the drinking water, and to fast (48 h). Production of reactive oxygen metabolites was measured by luminol amplified chemiluminescence (CL) in preparations of peritoneal cells activated by serum treated zymosan (STZ). Administration of CS which led to an increase in plasma CS from 31 (controls) to 46 ng mL-1, reduced CL (per cell) by 31%. Fast, which did not change plasma CS or ACTH, also had an inhibitory effect on CL (-25%), while the combination of CS administration and fast strongly inhibited the CL (-89%), indicating that plasma CS and fast reduced CL in a synergistic way. Similar effects on cell number were observed: CS-administration, fast and the combination reduced macrophage numbers (-13, -19.7 and -55%), while no significant effect was observed on the number of monocytes. The effect of adrenalectomy (adx) was studied in another series of experiments; adx induced no significant change in peritoneal leucocyte number or composition, while cells from adx animals had significantly higher chemiluminescence reaction than cells from sham operated animals. CS substitution in adx animals reduced CL by 30% while sham operated animals had 49% lower CL in adx. The data from adx animals also suggest that endogenous levels of CS are inhibitory for CL, but the results are not conclusive for the effect of very low doses of CS since other mechanisms than elimination of CS could prime the chemiluminescence reaction after adx. In conclusion, a moderate elevation of CS after systemic administration in vivo reduced the total number of mononuclear phagocytes in rat peritoneum, reduced the relative number of macrophages compared with monocytes, and suppressed the function of monocytes/macrophages by reducing the production of reactive oxygen molecules in activated cells. Furthermore, the effect of corticosterone was also dependent on the physiological situation, since the effects of fast and corticosterone were synergistic.

Effect of fluticasone propionate on neutrophil chemotaxis, superoxide generation, and extracellular proteolytic activity in vitro

BACKGROUND

Corticosteroids are widely used in the treatment of many inflammatory conditions but the exact mode of action on neutrophil function is uncertain. Fluticasone propionate is a new topically active synthetic steroid which can be measured in body fluids and which undergoes first pass metabolism.

METHODS

The effects of fluticasone propionate on the function of neutrophils isolated from normal, healthy control subjects and on the chemotactic activity of sputum sol phase were assessed.

RESULTS

Preincubation of neutrophils with fluticasone propionate reduced the chemotactic response to 10(-8) mol/l F-Met-Leu-Phe (FMLP) and to a 1:5 dilution of sputum sol phase in a dose dependent manner. Furthermore, when fluticasone propionate was added to sputum from eight patients with stable chronic obstructive bronchitis the chemotactic activity of a 1:5 dilution of the sol phase fell from a mean (SE) value of 22.2 (1.21) cells/field to 19.6 (0.89), 17.1 (0.74), and 11.9 (0.6) cells field at 1 mumol/l, 10 mumol/l, and 100 mumol/l, respectively. In further experiments fluticasone propionate preincubated with neutrophils inhibited fibronectin degradation by resting cells and by cells stimulated by FMLP (15.2% inhibition of resting cells, 5.1% inhibition of stimulated cells with 1 mumol/l fluticasone propionate, 24% and 18.7% inhibition respectively at 100 mumol/l fluticasone propionate. Fluticasone propionate had no effect on generation of superoxide anion by resting or stimulated cells.

CONCLUSIONS

These results indicate that fluticasone propionate has a direct suppressive effect on several aspects of neutrophil function and may suggest a role for this agent in the modulation of neutrophil mediated damage to connective tissue.

Methylprednisolone normalizes superoxide anion production by polymorphs from patients with ANCA-positive vasculitides

It has been convincingly documented that reactive oxygen species released from activated neutrophils mediate glomerular damage in experimental glomerulonephritis. Recent findings that antineutrophil cytoplasmic autoantibodies (ANCA) induce neutrophils to degranulate and produce oxygen radicals in vitro led us to explore whether neutrophils from patients with ANCA-positive vasculitides and necrotizing glomerulonephritis generated an increased amount of superoxide anion (O2-). Since glucocorticoids inhibit oxygen radicals generation in vitro we also evaluated the effect of intravenous pulses of methylprednisolone. Polymorphs were isolated from peripheral blood collected before (basal), 6 and 24 hours after the first infusion of methylprednisolone and 24 hours after the third one. O2- release by cells was assessed after 30 minute incubation without specific stimuli. Basal O2- release was significantly higher in patients than in controls (P < 0.01). Intravenous infusion of high doses of methylprednisolone markedly reduced O2- production with respect to the basal value, and the difference was statistically significant at various time interval considered after the steroid infusion. Besides reducing the excessive O2- formation, methylprednisolone induced an increase in polymorph expression of the gene encoding for manganese superoxide dismutase (Mn-SOD) enzyme. We conclude that polymorphs taken from patients with ANCA-positive vasculitides and necrotizing glomerulonephritis generate higher amounts of O2- than those from normal subjects. Methylprednisolone normalizes the abnormal generation of O2-, likely through its ability to up-regulate the gene for Mn-SOD, a potent antioxidant enzyme.

The effect of in vitro and in vivo dexamethasone on human neutrophil function

There is a significant fall in PMN chemotaxis to the peptide FMLP in response to increasing concentrations of dexamethasone in vitro. The response fell in a dose related manner from a control value of 53.7 SE +/- 9.6 cells per high power field (cpf) to 47.3 SE +/- 8.1 at 10(-6) M (p less than 0.05) and 24.7 +/- 8.9 at 10(-3) M (p less than 0.025). A similar response was observed for the chemoattractants zymosan activated serum and the sol phase of purulent sputum. The effect was independent of protein synthesis or the period of incubation. Twelve milligrams of dexamethasone taken daily by 6 healthy volunteers resulted in a significant (p less than 0.025) reduction in the chemotactic response of PMN to 10(-8) M FMLP (from 29.5 +/- 1.55 to 13.7 +/- 1.8 cpf) which was apparent within 2 hours of taking the first dose. This effect was sustained for the three days on which dexamethasone was taken but returned to normal 7 days after the last dose had been administered. Dexamethasone therapy had no effect on unstimulated PMN superoxide anion production either in vitro or in vivo. The in vivo effect on neutrophil function occurred at mean serum dexamethasone concentrations of 1.26 (+/- 0.28) X 10(-7) M on day 1, 1.44 (+/- 0.15) X 10(-7) M on day 2 and 1.31 (+/- 0.13) X 10(-7) M on day 3. Thus we conclude that dexamethasone concentration which inhibit PMN chemotaxis in vivo are much lower than those required to exert the same effect in vitro.

Superoxide anion hyperproduction by neutrophils in a case of myelodysplastic syndrome. Association with Sweet's syndrome and interstitial pneumonia

The complication of Sweet's syndrome and interstitial pneumonia occurred in a patient with myelodysplastic syndrome. Superoxide anion production by the patient's neutrophils was considerably higher than that by neutrophils obtained from normal controls after stimulation with opsonized zymosan, phorbol myristate acetate, or myristic acid. Prednisone, which a potent inhibitor of superoxide anion production by neutrophils, dramatically improved the skin and pulmonary lesions, suggesting that they were parts of the same clinical spectrum associated with the superoxide anion hyperproduction.

The influence of corticosteroids on host defense mechanisms

Glucocorticosteroid hormones affect virtually every tissue type in the body, including tissues of host-defense systems. There is an enormous body of literature concerning specific effects of corticosteroids on host defenses. This literature review examines the affects of corticosteroids on leukocyte kinetics, phagocytic immunity, cell-mediated immunity, and humoral immunity in steroid-resistant species.

Oxygen radicals, inflammation, and arthritis: pathophysiological considerations and implications for treatment

A vast amount of circumstantial evidence implicates oxygen-derived free radicals, especially superoxide and hydroxyl radical (and to lesser extent, hydrogen peroxide), as mediators of inflammation and/or tissue destruction in inflammatory and arthritic disorders. The substrates for radical generation, namely properly stimulated phagocytic cells, transition metal catalysts, and (to a limited extent) ischemia, are all amply present, although there is no particular rheumatic disease in which a consistent abnormality of radical generation has been identified. These radical species can clearly degrade hyaluronic acid, modify collagen and perhaps proteoglycan structure and/or synthesis, alter and interact with immunoglobulins, activate enzymes and inactivate their inhibitors, and possibly participate in chemotaxis. In most situations, however, there is ample scavenging ability to detoxify these radicals before they hit their target, and many rheumatic disease drugs can decrease their production and/or effects. Despite the apparent sufficiency of natural scavengers and the lack of direct evidence that oxygen radicals are pathogenetically important, substantial pharmaceutical effort is still being made to develop free radical scavengers as therapeutic agents. Although individual free radicals die out quickly, rheumatologic interest in them has been sustained for nearly two decades.

Effect of high-dose of methylprednisolone on tourniquet ischaemia

High doses of corticosteroids have been found to have beneficial effects in various shock states. It has been well recognized that ischaemia is one of the important features in shock states. This prompted us to investigate the effect of high-dose methylprednisolone on tourniquet-induced ischaemia using mongrel dogs. After inflation of tourniquets to 600 mmHg on each thigh of the hind legs, one leg received an intravenous infusion of methyl-prednisolone, 3 mg.kg-1 dissolved in 20 ml of autologous blood. The other leg received the same amount of blood only, as a control. During two hours of tourniquet time and until 30 min after tourniquet deflation, venous blood was sampled five times from both hind legs for measurements of blood gas tensions (PvO2, PvCO2) and pH, lactic acid, creatinine kinase (CK), aspartate aminotransferase (AST) and lactate dehydrogenase (LDH). During tourniquet ischaemia, PvO2 and pH dropped and PvCO2, lactic acid, CK, AST and LDH rose steadily and significantly in both groups of legs, indicating respiratory and metabolic acidosis, and muscle cell damage. However, those changes were significantly smaller in the methylprednisolone-treated legs. The beneficial effect of methylprednisolone could be attributed to its vasodilatory effect, cellular membrane stabilization and direct metabolic effect on skeletal muscle cells. Although the tourniquet-induced ischaemia in our study is slightly different from the clinical paradigm, the results suggest that high-dose methylprednisolone may provide a beneficial effect during tourniquet ischaemia.

The effect of dexamethasone in vivo on blood and peritoneal neutrophils (PMN) in rabbits with peritonitis

Neutrophils play an essential role in the host's defense against infection. Our previous studies have shown that blood and peritoneal neutrophils (PMN) have different basal activities and responses to infection. We also demonstrated that peritonitis produces divergent changes in the cellular function of PMN both in the blood and in the peritoneal fluid. Steroids are well documented to cause immunosuppression both clinically and, more variably, at the cellular level. Understanding the mechanism of steroid-induced immunosuppression in surgical infection may impart insight on the management of this condition. Using a model of surgical peritonitis, we studied the effects of immunosuppression on rabbit blood and peritoneal PMN. Blood and peritoneal PMNs were harvested after the development of fibrinopurulent peritonitis. Rabbits were divided into two groups: immunosuppressed and control. Immunosuppression was accomplished by intramuscular injection of dexamethasone (2 mg/kg) for 10 days preoperatively and 10 days postoperatively. Purified PMNs were studied for phagocytosis, adhesiveness, superoxide anion production and chemotaxis from both groups. Survival was computed from the number of days the rabbit survived after the operation up to a total of 10 at which time they were sacrificed. Immunosuppression with dexamethasone resulted in inhibition of peritoneal phagocytosis and peritoneal adhesiveness; there were no changes in blood adhesiveness nor blood phagocytosis. Also, there was no significant change in superoxide anion production nor in chemotaxis. Survival of the rabbits was significantly reduced when treated with dexamethasone.(ABSTRACT TRUNCATED AT 250 WORDS)

Mammary leukocyte response to drug therapy

The possibility exists that antibiotics and anti-inflammatory agents will be used indiscriminately in attempts to reduce leukocyte or somatic cell counts in mammary secretions to conform with Interstate Milk Shippers quality standards for raw milk to be implemented July 1, 1986. Recent in vivo studies evaluating the effect of intramammary drug injection on milk leukocytes confirmed previous in vitro investigations demonstrating that certain drugs have a significant effect on leukocyte antimicrobial activity. Antibiotics commonly included in commercial infusion products used in this country such as penicillin G, semisynthetic penicillins, the mycins, cephalosporins, and sulfonamides did not affect leukocyte function. However, some drugs were detrimental, notably chloramphenicol, tiamulin, tetracycline, gentamicin, rifampicin, amikacin, and nitrofurantoin. In vitro investigations on the use of anti-inflammatory agents demonstrated that methylprednisolone had a stabilizing effect on leukocytes by maintaining viability and reducing degranulation, whereas flumethasone was detrimental to cell viability. The nonsteroid agent, ibuprofen, decreased viability and increased degranulation but also increased phagocytosis and bacterial killing. Intramammary infusion of anti-inflammatory agents was generally ineffective in lowering somatic cell counts of endotoxin-infused quarters, but certain drugs may be advantageous in limiting milk production losses during udder inflammation.

Is macrophage-induced microthrombosis during endotoxemia dependent on prostaglandin synthesis?

Steroids and nonsteroidal anti-inflammatory drugs (NSAID), in addition to inhibiting prostaglandin synthesis, have recently been shown to block production of procoagulant activity (PCA) by alveolar macrophages (A-M phi). This inhibition may ameliorate one deleterious effect of endotoxin (LPS), since LPS-induced PCA may contribute to the diffuse microvascular thrombosis (DIC) and subsequent organ failure seen in endotoxemia. However, the results of treatment of endotoxemia with steroids of NSAID are variable or short-lived. To help elucidate the basis for these results, the effect of these agents on production of PCA by another M phi population, the hepatic M phi (H-M phi PCA is functionally discrete from A-M phi PCA) was evaluated. Four agents, (hydrocortisone, indomethacin, ibuprofen and acetylsalicylic acid (ASA)) used to both block production of prostaglandins and ameliorate the deleterious effects of LPS in vivo were tested on the production of rabbit M phi PCA in vitro in homogeneous cultures. PCA was measured by a standardized one-step coagulation assay. Treatment with LPS (1 to 10 g/ml) produced maximal stimulation of PCA production with a peak at 8 hr with PCA levels 20- to 30+-fold higher than controls. The effect of pretreatment (T-10 min) of M phi cultures with the various inhibitors on PCA production at 8 hr post-LPS was evaluated, (N = 6 to 10 experiments).(ABSTRACT TRUNCATED AT 250 WORDS)

Human polymorphonuclear leukocytes of the bone marrow, circulation, and marginated pool: function and granule protein content

Polymorphonuclear leukocytes (PMN) demonstrate altered function during acute infections and after administration of corticosteroids. We questioned whether or not such changes are due to population shifts from functionally different compartments of the granulocyte pool. Volunteers were given epinephrine to induce demargination or hydrocortisone (HC) to promote egress of PMN from the bone marrow. PMN obtained before and after drug administration were compared for adherence, chemotaxis, luminol-enhanced chemiluminescence, and total content and release of lactoferrin (LF), myeloperoxidase (MPO), and beta-glucuronidase (beta-glu). Epinephrine induced a significant neutrophilia of mature PMN (segmented neutrophils), but there were no changes in function or granule protein content. HC induced a significant neutrophilia with segmented neutrophils and immature PMN (bands). Circulating PMN obtained 4 hr after HC administration demonstrated less adherence, increased chemiluminescence, increased MPO release, and decreased MPO content. Band neutrophils, however, were more adherent than segmented PMN and showed a similar decrease in adherence following HC in vivo. Thus alteration of PMN adherence following intravenous corticosteroids is not due to an influx of immature neutrophils. On the other hand, it is possible that MPO content and release and capacity for oxidative metabolism change as PMN mature.

Effect of cimetidine, hydrocortisone superoxide dismutase and catalase on the development of oedema after thermal injury

A new hypothesis for the pathophysiological mechanism underlying the development of oedema after a thermal injury has been tested in an experimental burn model. Support was given to the suggestion that oxygen-derived free radicals produced by invading leucocytes which upon activation release the superoxide radical (O2-), may be partly responsible for the increase in microvascular permeability seen after thermal injury. By removal of oxygen-derived free radicals with radical scavengers (superoxide dismutase and catalases) it was possible to reduce significantly the post-burn oedema formation. For comparison, one series of rats was pretreated with hydrocortisone and another with the histamine H2-blocker cimetidine. Hydrocortisone reduced the very early post-burn oedema formation which might partly be due to its membrane-stabilizing influence and partly to a direct effect on the microvasculature, causing a reduction of the vasodilatation observed post-burn. The inhibition of post-burn oedema formation by cimetidine, earlier demonstrated in animal burn models, was confirmed in the present study. The mean arterial blood pressure (MAP) in the cimetidine-treated rats decreased, however, after treatment. It is therefore difficult to determine to what extent the concentration of oedema is attributable to histamine H2-receptor blockade and to what extent to the reduced blood pressure. The influence of MAP on post-burn odema formation was further illustrated in two series of rats anaesthetized with Inactin an Hypnorm/Valium respectively. The results underline the importance of using the same anaesthetic throughout the experimental series.

In vitro effect of hydrocortisone on the attachment and ingestion phases of immunoglobulin G- and complement component 3b-mediated phagocytosis by human neutrophils

The fluorescence quenching method (FQ method) was used to investigate the effect of hydrocortisone on the attachment and ingestion phases of immunoglobulin G (IgG)- and complement component 3b (C3b)-mediated phagocytosis by human neutrophils (PMNs). The results were compared with metabolic activity (O2- release) of the phagocytes. When the PMNs were treated with 5 X 10(-5) M hydrocortisone or more, both IgG-mediated and C3b-mediated interactions decreased. The number of intracellular particles decreased as the total number of PMN-associated particles decreased, indicating an effect mainly on particle attachment. This was substantiated by the fact that pretreatment of the PMN with cytochalasin B resulted in a hydrocortisone dose-related decrease of interacting particles. The FQ method made it possible to quantify the stimulus-phagocyte interaction in relation to the metabolic response. Superoxide anion release decreased at the highest concentration of hydrocortisone used (5 X 10(-3) M), which merely reflected the decreased number of interacting particles. No reduction in metabolic activation was obtained when the superoxide anion release was correlated with the number of interacting yeast-IgG particles. The results indicate that hydrocortisone primarily affects the binding capacity of Fc and C3b receptors, resulting in decreased metabolic activation. The effector functions, e.g., ingestion and metabolic activation, were not affected by hydrocortisone in this study.

Effect of corticosteroids on the production of superoxide and hydrogen peroxide and the appearance of chemiluminescence by phagocytosing polymorphonuclear leukocytes

Human polymorphonuclear leukocytes were incubated with either methylprednisolone sodium succinate, hydrocortisone sodium succinate, or distilled water, and then latex spherules were added as target particles for phagocytosis. At low concentrations of these corticosteroids (0.04-0.22 mM), no effect was observed on O2-. production, H2O2 production, or chemiluminescence. At high concentrations of these steroids (2.7 mM), a significant inhibition was observed in both O2-. production and H2O2 production. At 2.7 mM, methylprednisolone sodium succinate significantly decreased chemiluminescence, whereas hydrocortisone sodium succinate was without effect on chemiluminescence.