Reduction by dexamethasone of chemotactic activity in inflammatory exudates

Review of dexamethasone administration for management of complications in postoperative third molar surgery

Dexamethasone has been used in oral and maxillofacial surgery for postoperative pain, swelling, and trismus following third molar surgeries. It is a potent and powerful drug that can alleviate the aforementioned postoperative sequelae. Dexamethasone is responsible for inhibiting the release of inflammatory mediators in the inflammation process to improve patient quality of life after surgical intervention. There are several available routes of administering dexamethasone. This article will help determine the suggested routes of administration, dosage, parameters, and dexamethasone timing for third molar surgeries.

Microglial chemotaxis, activation, and phagocytosis of amyloid beta-peptide as linked phenomena in Alzheimer's disease

Microglia are widely held to play important pathophysiologic roles in Alzheimer's disease (AD). On exposure to amyloid beta peptide (A beta) they exhibit chemotactic, phagocytic, phenotypic and secretory responses consistent with scavenger cell activity in a localized inflammatory setting. Because AD microglial chemotaxis, phagocytosis, and secretory activity have common, tightly linked soluble intermediaries (e.g., cytokines, chemokines), cell surface intermediaries (e.g., receptors, opsonins), and stimuli (e.g., highly inert A beta deposits and exposed neurofibrilly tangles), the mechanisms for microglial clearance of A beta are necessarily coupled to localized inflammatory mechanisms that can be cytotoxic to nearby tissue. This presents a critical dilemma for strategies to remove A beta by enhancing micoglial activation--a dilemma that warrants substantial further investigation.

Inflammatory repertoire of Alzheimer's disease and nondemented elderly microglia in vitro

We have previously developed and characterized isolated microglia and astrocyte cultures from rapid (<4 h) brain autopsies of Alzheimer's disease (AD) and nondemented elderly control (ND) patients. In the present study, we evaluate the inflammatory repertoire of AD and ND microglia cultured from white matter (corpus callosum) and gray matter (superior frontal gyrus) with respect to three major proinflammatory cytokines, three chemokines, a classical pathway complement component, a scavenger cell growth factor, and a reactive nitrogen intermediate. Significant, dose-dependent increases in the production of pro-interleukin-1beta (pro-IL-1beta), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), monocyte chemoattractant protein-1 (MCP-1), macrophage inflammatory peptide-1alpha (MIP-1alpha), IL-8, and macrophage colony-stimulating factor (M-CSF) were observed after exposure to pre-aggregated amyloid beta peptide (1-42) (Abeta1-42). Across constitutive and Abeta-stimulated conditions, secretion of complement component C1q, a reactive nitrogen intermediate, and M-CSF was significantly higher in AD compared with ND microglia. Taken together with previous in situ hybridization findings, these results demonstrate unequivocally that elderly human microglia provide a brain endogenous source for a wide range of inflammatory mediators.

The in vitro effects of estradiol and cortisol on the function of a long-term goldfish macrophage cell line

We examined the in vitro effects of estradiol and cortisol on the inflammatory function of a macrophage cell line. A dose-dependent inhibition of chemotaxis (0.5 and 0.1 microM, for estradiol and cortisol, respectively) and phagocytosis (1.0 microM for both steroids) were observed after treatment. Estradiol did not affect the nitric oxide production by the macrophage cell line, while cortisol strongly inhibited in vitro nitric oxide production. The steroids did not affect the ability of the macrophages to mount a respiratory burst response as measured by the NBT reduction assay.

Inhibitory effect of 4-acylaminophenol derivatives (T-0799 and T-0757), novel lipoxygenase inhibitors, on arachidonic acid-induced infiltration of polymorphonuclear leukocytes in rat skin

Effects of 4-acylaminophenol derivatives, novel 5-lipoxygenase inhibitors, on the neutrophil infiltration in arachidonic acid (AA) (10 mg/site)-induced skin inflammation in rats were examined. Myeloperoxidase (MPO) activity in the skin lesion, used as an indicator of neutrophil infiltration, was significantly increased after intradermal injection of AA. Dual inhibitors of cyclooxygenase and 5-lipoxygenase, phenidone (100 mg/kg x 2, i.p. and p.o.) and BW-755C (50 mg/kg x 2, p.o.), and 5-lipoxygenase inhibitors, AA-861 (100 mg/kg x 2, i.p.) and the 4-acylaminophenol derivatives T-0799 and T-0757 (10-100 mg/kg x 2, p.o.), inhibited the increase in MPO activity 5 hr after AA-injection, but the cyclooxygenase inhibitor indomethacin (5 mg/kg, i.p.) showed no effect. These results suggest that products of lipoxygenase, but not of cyclooxygenase, are involved in the MPO activity increase (i.e., neutrophil infiltration), and that this model is useful for in vivo evaluation of 5-lipoxygenase inhibitors. It is suggested that the 4-acylaminophenol derivatives may be useful as orally active drugs for treatment of some leukotriene-mediated diseases.

Schistosoma mansoni: the effect of dexamethasone on the cercaria-schistosomulum transformation, in vivo

Treatment with dexamethasone (DMS) in the early phases of the experimental Schistosoma mansoni infection causes an indirect effect on the cercaria-schistosomulum transformation process. This is observed when naive albino mice are treated with that drug (50 mg/Kg, subcutaneously) and infected intraperitoneally 01 hour later with about 500 S. mansoni cercariae (LE strain). An inhibition in the host cell adhesion to the larvae, with a simultaneous delay in the cercaria-schistosomulum transformation, is observed. This effect is probably due to a blockade of the neutrophil migration to the peritoneal cavity of mice, by an impairment of the release of chemotactic substances. Such delay probably favors the killing of S. mansoni larvae, still in the transformation process, by the vertebrate host defenses, as the complement system.

In vivo Mononuclear Phagocyte Migration: Paradoxical Effect of Adrenalectomy

The effect of adrenalectomy on neutrophil and monocyte migration into rat peritoneal and pleural cavities was investigated. Carrageenin- or thioglycollate-induced neutrophil emigration into both cavities was enhanced by adrenalectomy. In contrast, monocyte migration into peritoneal cavities induced by these two stimuli was significantl decreased. In pleural cavities, adrenalectomy enhanced the monocyte migration induced by carrageenin but had no effect on that induced by thioglycollate. Administration of physiological doses of glucocorticoids reversed the effect of adrenalectomy on monocyte migration by both stimuli into both cavities. The results support the hypothesis that endogenous glucocorticotds negatively control neutrophil migration independently of the site or type of stimulus. Their role in monocyte migration is, however, dependent on the site of injury and on the type of inflammatory stimulus. There is no obvious explanation for the divergent influence of endogenous glucocorticoids on the monocyte emigration into peritoneal and pleural cavities observed with different stimuli.

Infection with Toxoplasma gondii does not Alter TNFalpha and IL-6 Secretion by A human Astrocytoma Cell Line

The secretion of tumour necrosis factor-α (TNFα), interleukin-1α (IL-α) and interleukin-6 (IL-6) by a human astrocytoma cell fine was studied 1 h, 3 h, 6 h and 24 h after infection with tachyzoites from three Toxoplasma gondii strains (virulent, RH; cystogentc, 76K and Prugniaud strains). The astrocytoma cell fine constitutively secreted TNFα and IL-6, but no IL-1α. A positive control was obtained by stimulation with phorbol esters inducing a significant increase (p < 0.05) in TNFα and IL- 6 secretion but not in IL-1α, while lipopolysaccharide (alone and after priming), interferon gamma, ionophore A 23187 and sera positive to T. gondii did not induce any increase in cytokine levels. None of the tachyzoites, whatever their virulence, induced a significant increase in cytokine production at any time in the study. Tachyzoites did not inhibit the secretion induced by phorbol esters.

Alteration of neutrophil (PMN) function by heparin, dexamethasone, and enalapril

The aim of this study is to investigate the effect of a seemingly divergent class of pharmacologic agents, each having been reported to suppress intimal hyperplasia, on neutrophil (PMN) function. Human PMNs were isolated and exposed for 30 min to either saline or one of three different pharmacologic agents, each tested at three different concentrations: Group 1, saline (control, n = 14); Groups 2-4, heparin (5000 units, n = 8; 2500 units, n = 6; 1250 units, n = 6) respectively; Groups 5-7, dexamethasone (4 mg, n = 8; 2 mg, n = 6; 1 mg, n = 6), respectively; and Groups 8-10, enalapril (1.25 mg, n = 8; 0.62 mg, n = 6; 0.31 mg, n = 6). Superoxide anion production was measured by the reduction of cytochrome c in a spectrophotometric assay. Chemotaxis was evaluated by the number of PMNs migrating across a filter using a Neuro Probe chamber. Phagocytosis was determined by the ingestion of opsonized zymosan particles by PMNs. Serum obtained from each PMN donor was used both to opsonize the zymosan and as a chemoattractant in the chemotaxis assay. No agent, at any dose, significantly changed superoxide production when compared to control cells. All three agents significantly inhibited PMN chemotaxis at every dose tested (P less than 0.01). In the phagocytosis assay, both heparin (at high and intermediate doses) and enalapril (at all doses) significantly reduced phagocytic activity (P less than 0.01); however, dexamethasone (at high and intermediate doses) produced a marked stimulation (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Persistent experimental Salmonella dublin intramammary infection in dairy cows

Experimental intramammary infections were induced in five post-parturient Holstein cows by inoculation of low numbers (5000 colony forming units) of virulent Salmonella dublin via the teat canal of mammary gland quarters. Rectal temperature, pulse and respiratory rates, milk yield, and milk quality as assessed by the California Mastitis Test (CMT) and somatic cell counts (SCC) were recorded every 12 hours at milking. Bacteriologic cultures of foremilk quarter samples and feces were obtained daily, as were complete blood counts. ELISA titers for IgG and IgM recognizing S. dublin lipopolysaccharide (LPS) were obtained weekly on serum and quarter milk samples. All cows excreted S. dublin intermittently from infected quarters, but no changes were detected in rectal temperature, appearance of the mammary gland or secretions, CBC, milk yield, and pulse and respiratory rates. Somatic cell counts were modestly increased in infected quarters as compared with uninfected quarters (P = .015, paired t test); however, CMT scores after infection remained low, and were not significantly different from pre-infection scores (P greater than .10, sign test). After infection, administration of dexamethasone resulted in signs of clinical mastitis and increased excretion of S. dublin from mammary quarters (P = .0004, paired t test). One cow had necrotizing mastitis and S. dublin septicemia and was euthanatized. In the four surviving cows, clinical improvement was observed after systemic gentamicin therapy and intramammary infusion with polymyxin B, but all cows continued to excrete S. dublin intermittently from one or more quarters and occasionally from feces for the remaining period of observation. All infected cows demonstrated a rise in IgG and IgM ELISA titers recognizing S. dublin LPS in serum and milk. At necropsy (13-25 weeks postinfection), S. dublin was recovered only from the mammary tissue or supramammary lymph nodes in three of four cows. In one cow, mammary gland and lymph-node samples were negative for S. dublin despite positive milk cultures. In all cows, histopathologic examination revealed multifocal areas of chronic active mastitis. These lesions were similar to histopathologic findings from mammary gland carriers with naturally acquired S. dublin infection.

Review article: the pharmacological implications of leucocyte-endothelial cell interactions in Crohn's disease

The importance of leucocyte-endothelial cell interactions in the inflammatory process is now recognized. In Crohn's disease, we have proposed that these interactions mediate not only the development of the parenchymal cell infiltrate, but also initiate a process (multifocal gastrointestinal infarction) that leads to ischaemic damage to the bowel wall. We review data on the actions of drugs in the treatment of Crohn's disease and, where known, we highlight their effects on leucocyte adhesion to the endothelium. Corticosteroids inhibit adhesion by inhibiting production of interleukin-1, tumour necrosis factor, interferon gamma, leukotrienes and platelet activating factor. Drugs liberating 5-aminosalicylate inhibit leukotriene production. Cyclosporin inhibits T-cell activation, and amplification of the immune response. Inhibition of leucocyte--endothelial cell interactions probably accounts for some of the beneficial effects of these drugs in Crohn's disease.

Stimulation of neutrophil adherence to vascular endothelial cells by histamine and thrombin and its inhibition by PAF antagonists and dexamethasone

1. In order to clarify the roles of platelet-activating factor (PAF) in histamine- and thrombin-induced neutrophil adhesion to vascular endothelial cells, the effects of several PAF antagonists were examined. The effects of the glucocorticoid dexamethasone were also examined in order to gain further insight into the anti-inflammatory actions of glucocorticoids. 2. In culture, histamine and thrombin stimulated the adherence of rat peritoneal neutrophils to human endothelial cells from the umbilical vein. They did not stimulate neutrophil adherence in the absence of endothelial cells, suggesting that the target cells for the histamine- and thrombin-induced adherence of neutrophils were endothelial cells, not neutrophils. 3. Several PAF antagonists, such as CV-3988, L-652,731 and Y-24,180 inhibited the histamine- and thrombin-induced neutrophil adherence in a concentration-dependent manner. Indomethacin failed to inhibit it. 4. Dexamethasone, a steroidal anti-inflammatory drug, did not inhibit the histamine- and thrombin-induced adherence of neutrophils to endothelial cells when the drug was present only during the 20 min incubation period for the adherence assay. When the endothelial cells were preincubated for 3 h with dexamethasone, the adherence of neutrophils to endothelial cells induced by histamine or thrombin was not inhibited. 5. When the neutrophils were preincubated for 3 h with dexamethasone, the histamine- and thrombin-induced adherence of neutrophils to endothelial cells was inhibited. 6. Our studies indicate that: (a) adherence of neutrophils to endothelial cells induced by histamine and thrombin is mediated by PAF production since PAF antagonists inhibited the adherence of neutrophils; and (b) neutrophils, not endothelial cells, are the target cells through which dexamethasone acts to inhibit adherence.

Mechanism of the inhibitory action of cyclooxygenase inhibitors on leukocyte infiltration: involvement of endogenous histamine

The mechanism of the inhibitory action of cyclooxygenase inhibitors on leukocyte accumulation in the inflammatory locus was investigated in an allergic inflammation of the air pouch types in rats. Three kinds of cyclooxygenase inhibitors, indomethacin, diclofenac and tiaprofenic acid, caused not only inhibition of the vascular permeability response and leukocyte accumulation but also elevation of histamine levels in the exudate. These effects of indomethacin were all reversed by local administration of prostaglandin E2. Pyrilamine, an H1 antagonist, did not affect the anti-inflammatory actions of indomethacin. The H2 antagonists, cimetidine, ranitidine and famotidine, decreased the inhibitory effect of indomethacin on leukocyte accumulation without affecting the inhibitory action on vascular permeability. These results indicate that the inhibitory action of cyclooxygenase inhibitors on leukocyte accumulation is derived from their blocking effect against generation of PGE2 which works as an inhibitory factor on the production of histamine in the inflammatory tissues.

Inflammatory responses in cuff-induced atherosclerosis in rabbits

Cuff-treatment of the rabbit carotid artery produced a diffuse intimal thickening which resembled early lesions of atherosclerosis. A limited amount of focal endothelial damage occurred first (0.5 h), leukocytes infiltrated the subendothelium and extensive endothelial denudation occurred at 24 h. At 3 days, the regenerating endothelium covered the denuded area, and the media was edematous. At 7 days proliferation of intimal cells became visible. Maximum intimal thickening occurred at 3 weeks. Daily injection of dexamethasone (0.01-10 mg/kg i.m.) and ticlopidine (1-100 mg/kg i.m.) dose-dependently attenuated the intimal thickening. Indomethacin had little effect. Inflammatory exudate from zymosan-activated air pouch induced chemotaxis of rat smooth muscle cells (SMC) in vitro. Similar chemotactic activity was observed with leukotriene B4 (LTB4) but not with the other lipoxygenase products tested. The exudate contained reasonable amounts of LTB4, which would account for its chemotactic activity. Dexamethasone inhibited the chemotaxis by the exudate and proliferation of SMC. These results are discussed in relation to the mechanism of atherogenesis. It is concluded that leukocytes play a major role in cuff-induced intimal thickening, and that their products cause endothelial denudation and SMC chemotaxis. Involvement of platelet aggregation in atherogenesis is also suggested.

The release of a neutrophil chemotactic factor from peritoneal macrophages by endotoxin: inhibition by glucocorticoids

Glucocorticoids inhibit the migration of neutrophils induced by endotoxin (E. coli lipopolysaccharide, LPS) in vivo. Macrophage monolayers stimulated by LPS showed a dose-dependent release into the supernatant of a chemotactic factor for neutrophils, MNCF, which was active in vivo and in vitro. Dexamethasone reduced the neutrophil migration into the abdominal cavities of rats that was induced by LPS, but did not affect the migration induced by MNCF. The release of MNCF by LPS-pretreated macrophage monolayers was inhibited by dexamethasone and hydrocortisone but not by indomethacin and BW755C. MNCF was stable at 56 degrees C and did not release histamine from mast cells. Thus, MNCF activity seems not to be due to arachidonic acid metabolites or C5/C5a. MNCF shares some properties with interleukin-I, such as the blockade of its release by glucocorticoids, the association of its activity with a material of a molecular weight greater than 10 000 Daltons and the abolition of its activity by incubation with phenylglyoxal. However MNCF liberation was not blocked by cycloheximide and the time course of its release by macrophage monolayers stimulated by LPS differed from that described for interleukin-1. In addition human interleukin-1 when tested in dexamethasone-treated test rats failed to induce neutrophil migration. It is suggested that inhibition by glucocorticoids of LPS-induced neutrophil migration in vivo is not due to a direct effect upon the migrating cells but rather to an indirect one, i.e. through blockade of MNCF release by macrophages.

Vascular permeability responses and the role of prostaglandin E2 in an experimental allergic inflammation of air pouch type in rats

Rats were sensitized with azobenzene arsonate-conjugated acetyl bovine serum albumin. An allergic inflammation was induced in the preformed air pouch in the dorsum of the sensitized rats by injecting the antigen dissolved in a 2% sodium carboxymethyl cellulose solution into the air pouch. Time course changes of vascular permeability, accumulated pouch fluid volume and prostaglandin E2 (PGE2) levels in the pouch fluid were compared in sensitized and non-sensitized rats to characterize the allergic inflammatory reaction. Effects of three cyclo-oxygenase inhibitors (indomethacin, diclofenac sodium and tiaprofenic acid) on vascular permeability and accumulated pouch fluid volume 4 and 24 h after the immunological challenge injection were examined to elucidate a possible role of PGE2 in the inflammatory response. Four h after initiating the allergic reaction, although the level of PGE2 in the pouch fluid reached a high level, the vascular permeability response, measured over the period 3.5-4 h, was not suppressed by treatment with the three cyclo-oxygenase inhibitors and neither was the pouch fluid volume measured over the period 0-4 h. However, vascular permeability and accumulated pouch fluid volume at 24 h were suppressed by the cyclo-oxygenase inhibitors in a dose-dependent manner. These observations suggest that in this model, endogenous PGE2 does not affect oedema formation measured at 4 h. However, oedema formation measured at 24 h may be dependent on PGE2 generation.

A new simple plastic chemotaxis device of the Boyden chamber type utilizing an immunoassay plate

A new simple and economical plastic Boyden chamber for in vitro assay of leukocytes chemotaxis was devised by the use of a commercially available immunoassay plate. Zymosan-activated rat serum, formyl-methionyl-leucyl-phenylalanine and leukotriene B4 caused concentration-dependent migration of the leukocytes into the lower chamber. About 50% of the cells loaded in the upper chamber migrated into the lower chamber for 80 min at the optimal concentrations of the three chemoattractants tested.