Mobilization and extracellular release of granular enzymes from human leukocytes during phagocytosis: inhibition by colchicine and cortisol but not by salicylate

Predictive value of baseline alpha defensin level in patients with stable coronary artery disease: A retrospective single center study

Background

Inflammation plays a central role in atherogenesis. The major neutrophilic peptide alpha-defensin is a promising evolving risk factor for atherosclerosis. The aim of the present study was to examine the role of alpha-defensin in predicting future major adverse cardiovascular events (MACE) occurrence in fully revascularized patients with stable CAD under optimal medical therapy.

Methods and results

We retrospectively examined the prognostic value of baseline plasma alpha-defensin levels in predicting MACE occurrence in 174 fully revascularized patients for stable CAD between March 2016 and January 2017. Alpha-defensin levels were found 20 % higher among demised patients (10,859 pg/ml, IQR [6,920 to 23,320] vs. 9,020 pg/ml, IQR [5,540 to 16,180] pg/ml, P = 0.15). The absolute increase in mortality risk in patients with alpha-defensin levels greater than the median values was 72.5 % (P = 0.33). Log-rank analysis proved both recurrent PCI for de novo lesions (14.9 % and 2.3 %) and the composite of mortality and recurrent PCI for de novo lesions (27.6 % vs. 9.2 %) were significantly related to alpha-defensin values greater than the median (>9200 pg/ml).

Conclusion

Baseline plasma alpha-defensin is an independent predictor of mortality and recurrent PCI among patients with stable CAD. Alpha-defensin may evolve as a promising factor in cardiovascular risk assessment beyond traditional risk factors. Targeting alpha-defensin to ameliorate MACE occurrence should be addressed in future studies.

Micro- and Macrovascular Effects of Inflammation in Peripheral Artery Disease-Pathophysiology and Translational Therapeutic Approaches

Inflammation has a critical role in the development and progression of atherosclerosis. On the molecular level, inflammatory pathways negatively impact endothelial barrier properties and thus, tissue homeostasis. Conformational changes and destruction of the glycocalyx further promote pro-inflammatory pathways also contributing to pro-coagulability and a prothrombotic state. In addition, changes in the extracellular matrix composition lead to (peri-)vascular remodelling and alterations of the vessel wall, e.g., aneurysm formation. Moreover, progressive fibrosis leads to reduced tissue perfusion due to loss of functional capillaries. The present review aims at discussing the molecular and clinical effects of inflammatory processes on the micro- and macrovasculature with a focus on peripheral artery disease.

IgA Vasculitis: Etiology, Treatment, Biomarkers and Epigenetic Changes

IgA, previously called Henoch-Schönlein vasculitis, is an essential immune component that drives the host immune response to the external environment. As IgA has the unique characteristic of a flexible response to broad types of microorganisms, it sometimes causes an autoreactive response in the host human body. IgA vasculitis and related organ dysfunction are representative IgA-mediated autoimmune diseases; bacterial and viral infections often trigger IgA vasculitis. Recent drug developments and the presence of COVID-19 have revealed that these agents can also trigger IgA vasculitis. These findings provide a novel understanding of the pathogenesis of IgA vasculitis. In this review, we focus on the characteristics of IgA and symptoms of IgA vasculitis and other organ dysfunction. We also mention the therapeutic approach, biomarkers, novel triggers for IgA vasculitis, and epigenetic modifications in patients with IgA vasculitis.

Colchicine use is associated with decreased prevalence of myocardial infarction in patients with gout

OBJECTIVE

The ability of antiinflammatory strategies to alter cardiovascular risk has not been rigorously examined. Colchicine is an antiinflammatory agent that affects macrophages, neutrophils, and endothelial cells, all of which are implicated in the pathogenesis of cardiovascular disease. We examined whether colchicine use was associated with a reduced risk of myocardial infarction (MI) in patients with gout.

METHODS

We conducted a retrospective, cross-sectional study of all patients with an International Classification of Diseases, 9th ed, code for gout in the electronic medical record (EMR) of the New York Harbor Healthcare System Veterans Affairs network and ≥ 1 hospital visit between August 2007 and August 2008. Hospital pharmacy data were used to identify patients who had filled at least 1 colchicine prescription versus those who had not. Demographics and CV comorbidities were collected by EMR review. The primary outcome was diagnosis of MI. Secondary outcomes included all-cause mortality and C-reactive protein (CRP) level.

RESULTS

In total, 1288 gout patients were identified. Colchicine (n = 576) and no colchicine (n = 712) groups had similar baseline demographics and serum urate levels. Prevalence of MI was 1.2% in the colchicine versus 2.6% in the no-colchicine group (p = 0.03). Colchicine users also had fewer deaths and lower CRP levels, although these did not achieve statistical significance. Colchicine effects persisted when allopurinol users were excluded from the analysis.

CONCLUSION

In this hypothesis-generating study, gout patients who took colchicine had a significantly lower prevalence of MI and exhibited trends toward reduced all-cause mortality and lower CRP level versus those who did not take colchicine.

Colchicine: its mechanism of action and efficacy in crystal-induced inflammation

New light has been shed on the mechanisms of action of colchicine in crystal-associated arthropathies. Colchicine, long used to treat gout, arrests microtubule assembly and inhibits many cellular functions. At micromolar concentrations, it suppresses monosodium urate crystal-induced NACHT-LRR-PYD-containing protein-3 (NALP3) inflammasome-driven caspase-1 activation, IL-1beta processing and release, and L-selectin expression on neutrophils. At nanomolar concentrations, colchicine blocks the release of a crystal-derived chemotactic factor from neutrophil lysosomes, blocks neutrophil adhesion to endothelium by modulating the distribution of adhesion molecules on the endothelial cells, and inhibits monosodium urate crystal-induced production of superoxide anions from neutrophils. Cyto-chrome P450 3A4, the multidrug transporter P-glycoprotein, and the drugs that bind these proteins influence its pharmacokinetics and pharmacodynamics. Trial evidence supports its efficacy in acute gout and in preventing gout flares, but it has narrow therapeutic index, and overdosage is associated with gastrointestinal, hepatic, renal, neuromuscular, and cerebral toxicity; bone marrow damage; and high mortality.

Exocytotic "constipation" is a mechanism of tubulin/lysosomal interaction in colchicine myopathy

Colchicine, a known microtubule disrupting agent, produces a human myopathy, characterized by accumulation of lysosomes. We have created a reliable animal model of colchicine myopathy that replicates the subacute myopathy seen in humans, reproducing the chronic proximal weakness and vacuolar changes in nonnecrotic myofibers. If a microtubule network plays a role in lysosomal function in muscle, disturbance of it could alter degradation of intrinsic membrane receptors, presumably at some intracellular processing site or at exocytosis. Thus, we examined, as a possible cellular pathogenesis of colchicine myopathy, how the muscle cytoskeleton affects the degradation of membrane proteins, which are processed through the endosomal/lysosomal pathway. We used the acetylcholine receptor as a model membrane component in cultured myotubes allowed to preincubate with colchicine. We tested at which step colchicine interferes with receptor trafficking by accounting for internalization, delivery to lysosomes, hydrolysis, or exocytotic release of debris. We report that colchicine significantly decreases the exocytosis of AChRs but does not affect receptor internalization, lysosomal hydrolysis, or the number of surface membrane receptors. Further, our immunofluorescence observations revealed a morphologic tubulin network in rat skeletal muscle that is more densely distributed in white (mitochondria-poor) muscle fibers than in red (mitochondria-rich) fibers but is present in both. Ultrastructurally, immunogold labeling localized tubulin in the intermyofibrillar region in a long and linear fashion, unassociated with myofibers or mitochondria. Taken together, our findings suggest the following: (1) Microtubules likely play a functional role in the pathway of lysosomal degradation in normal adult skeletal muscle; (2) The observed decrease in overall apparent degradation of membrane receptors by colchicine must be due primarily to inhibition of exocytosis. These data indicate that lysosomal "constipation" underlies colchicine myopathy. (3) An animal model faithful to the human disorder will allow further pathogenetic studies.

Update on colchicine and its mechanism of action

Colchicine is a unique anti-inflammatory drug with respect to its limited clinical usefulness and its mode of action. Colchicine is mainly indicated for the treatment and prophylaxis of gout and familial Mediterranean fever. Its mode of action includes modulation of chemokine and prostanoid production and inhibition of neutrophil and endothelial cell adhesion molecules by which it interferes with the initiation and amplification of the joint inflammation. This paper discusses its adverse effects and indications.

Rapid and reversible tubulin tyrosination in human neutrophils stimulated by the chemotactic peptide, fMet-Leu-Phe

Neutrophil activation by specific stimuli, such as the oligopeptide chemotactic factor fMet-Leu-Phe (fMLF), is associated with an increased enzymatic addition of tyrosine to tubulin alpha-subunits, as measured by 14C tyrosine uptake. In studies using immunoblots we have found that this increased tyrosine uptake into tubulin in activated neutrophils reflects an increase in the proportion of cellular tubulin that is tyrosinated rather than simply an increase in the turnover of tyrosinated subunits. However, the increased accumulation of tyrosinated tubulin was also found to follow an initial depletion of tyrosinated tubulin and concomitant increase in detyrosinated tubulin between 0 and 60 sec following stimulation of neutrophils with fMLF. Immunogold electron microscopy studies of intact microtubules recovered from activated neutrophils demonstrated that these rapid changes in the relative content of tubulin isoforms in the cells were not associated with the formation or disappearance of microtubule microdomains composed of only one form of tubulin. Previously, we have shown that under conditions of fMLF-stimulated exocytosis there is an increased binding of neutrophil granules to endogenous microtubules. Since neutrophil activation by fMLF is associated with increased tyrosination of alpha-tubulin subunits, we speculated that rapid changes in the levels of tyrosinated tubulin in the microtubules of activated neutrophils might have a role in the regulation of granule-microtubule interactions. When the binding of purified neutrophil granules to reconstituted rat brain microtubules containing approximately 50% tyrosinated tubulin was measured by electron microscopy and compared with granule binding to microtubules that contained no detectable tyrosinated tubulin, granule-microtubule associations were found to be significantly favored by detyrosinated vs. tyrosinated tubulin. These findings indicate that interactions between cytoplasmic granules and microtubules in activated neutrophils may be modulated by rapid changes in the relative content of detyrosinated and tyrosinated tubulin in the microtubule network of the cells.

Interactions of cytoplasmic granules with microtubules in human neutrophils

Ultrastructural and functional studies of degranulation responses by human neutrophils have suggested that microtubules (MTs) have a role in the intracellular transport of neutrophil granules. We have found that granule-MT complexes can be isolated from disrupted taxol-treated (1.0 microM) neutrophils, visualized by electron microscopy, and quantified in terms of granules per MT length. After incubation of neutrophils with the chemotactic peptide N-formyl-methionyl-leucyl-phenylalanine (fMLP), granule-MT complex formation was found to be increased two- to threefold. Enhanced binding of granules to MTs was detectable within 30 s of fMLP stimulation and was dependent on the concentration of fMLP. Incubation of cells with dibutyryl cAMP inhibited this fMLP-stimulated granule-MT complex formation in a dose-responsive fashion. These granule-MT interactions could be reproduced in a cell-free system with neutrophil granules isolated by density gradient centrifugation and MTs polymerized from phosphocellulose-purified tubulin. Furthermore, reconstituted granule-MT interactions were found to be modulated by ATPase inhibitors. Sodium orthovanadate increased granule-MT interactions in a concentration-dependent manner, while AMP-PNP, a nonhydrolyzable ATP analogue, and N-ethylmaleimide decreased or eliminated these interactions. In addition, we found that a MT-activated ATPase could be recovered from intact neutrophil granules by salt extraction, and that extracts enriched in this ATPase contained a polypeptide of between 115 and 120 kD which binds ATP and is immunologically related to kinesin. These studies demonstrate that cytoplasmic granules interact with MTs in human neutrophils in a regulated stimulus-responsive manner, and they suggest that such interactions may involve an MT-based, ATPase-dependent, vesicle translocation system as has been demonstrated in other types of cells.

Linkage between neutrophil degranulation and calcium discharge

Calcium flux across organelle and plasma membranes is an important event in neutrophil activation. We measured calcium discharge into the media from neutrophils stimulated with formyl-methionyl-leucyl-phenylalanine after treatment with cytochalasin b. Cytochalasin markedly potentiated calcium efflux from stimulated neutrophils, and similarly promoted release of lysosomal enzymes into the media. Colchicine neither reproduced nor modified the cytochalasin effect. Neutrophil cytoplasts discharged very little calcium in response to stimulation, and discharge was not significantly altered by cytochalasin b. These findings indicate that neutrophil degranulation is accompanied by efflux of calcium into the media, and suggest that the neutrophil granules constitute a source of mobilizable calcium which could be used to modify the extracellular microenvironment.

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.

Influence of fever temperatures and of some cytoactive drugs on in vitro lysozyme release from monocytes and granulocytes

The selective in vitro release of lysozyme from human monocytes and granulocytes was not greatly influenced by temperatures above 37 degrees C and up to 40 degrees C. The release was markedly inhibited by preincubation with phenylbutazone, oxyphenylbutazone, colchicine and vincristine. A water-soluble hydrocortisone complex also inhibited lysozyme release, but at high concentrations, lysis of the cells occurred. Although methotrexate had a weak inhibiting effect, no appreciable influence on release was observed with cyclophosphamide or cytarabine. Thus, release of lysozyme from blood leukocytes is likely to be dependent on cellular functions involving the stability of both microtubules and membranes.

Anomalous effects of anti-inflammatory corticosteroids in endotoxin-induced ocular inflammation

The effect of anti-inflammatory corticosteroids upon leukocyte infiltration was investigated in vivo, using the eye as an experimental model. The inflammatory response was induced by injecting bacterial endotoxin into the vitreous body of the albino rabbit eye. Polymorphonuclear leukocyte (PMN) infiltration into the aqueous humor was quantified by counting cells directly, whereas accumulation of leukocytes in the ocular tissues was determined by measuring myeloperoxidase (MPO) activity. Systemically administered corticosteroids inhibited plasma protein leakage and PMN infiltration into the aqueous humor, but, anomalously, increased MPO activity and hence the number of PMNs in the ciliary body. These findings were confirmed qualitatively by histology. However, the clinical manifestations of the inflammatory responses were almost totally suppressed by the corticosteroids. We suggest that the inhibitory effect of corticosteroids on PMN infiltration into the aqueous humor, and possibly inflammatory exudates in general, represents the suppression of inflammatory cell activity in a manner which is unrelated to a direct effect on leukocyte movement.

The effects of in vivo hydrocortisone on lymphocyte-mediated cytotoxicity

To examine the effects of in vivo hydrocortisone sodium succinate (HC) on natural killer (NK) cell and antibody-dependent cellular cytotoxicity (ADCC), 11 normal adults received a single intravenous bolus of 400 mg hydrocortisone. Lymphocytes were tested for NK activity and ADCC using 51chromium (51Cr)-release and single cell cytotoxicity assays against Molt-4 and sensitized RL O leads to target cells, respectively. Four hours after injection, both NK and ADCC activity were transiently increased in the 51Cr-release system (P less than 0.05). At 4 hours, there was a twofold increase in the relative frequency of potentially cytotoxic target binding cells (P less than 0.001) but the absolute number of these cells did not change (P less than 0.1). However, the percentage lysis of bound targets at 4 hours was not altered (P greater than 0.1). These data suggest that: 1) lymphocytes participating in NK and ADCC reactions are refractory to the kinetic and functional effects of HC; 2) the increased lytic activity observed at 4 hours is due to a selective depletion of noncytotoxic cells from the circulation; and 3) NK and ADCC activity did not differ in their responses to HC.

Influence of glucocorticoids on histamine release and 45calcium uptake by isolated rat mast cells

Hydrocortisone and prednisolone inhibited the histamine release from isolated rat mast cells induced by antigen, the ionophore A23187, and compound 48/80 in the absence and in the presence of calcium. Hydrocortisone reduced the response to the different releasing agents by 50% in the concentration range 2-6 X 10(-4) M, whereas prednisolone was about 1.5 times more potent. The inhibitory effect of hydrocortisone had a rapid onset of action and maximal inhibition was observed after preincubation for 20 minutes. The effect of hydrocortisone was reversed by including 2 mM glucose in the medium. The reversal was only partial with antigen and the ionophore A23187, indicating a greater energy requirement of these releasing agents compared with compound 48/80. The inhibition of the histamine release was accompanied by a concentration-related inhibition of the 45Ca uptake, except with the ionophore. The inhibition of the 45Ca uptake was also reversed by glucose, but differences were noted concerning the influence of preincubation time. The observations are explained by an association of 45Ca to cellular material, e.g. granules, secondary to the release process. The effects of hydrocortisone and prednisolone were qualitatively identical and were not observed with estriol. The glucocorticoid inhibition of histamine release does not seem to be caused by effects on phospholipase activity or cyclic AMP metabolism. The present observations are fully consistent with an impaired mitochondrial function as the mechanism for the mast cell effects of the glucocorticoids.

The efficacy of colchicine prophylaxis in articular gout--a reappraisal after 20 years

Prophylactic colchicine remains an efficacious drug in preventing recurrent attacks of acute gouty arthritis. Its use is indicated especially in those patients with frequent and severe attacks, and in those with coexisting medical complications. In the present study which reviews the experience of 540 patients, 518 males and 22 females over a period of more than 20 yr, excellent results were obtained in approximately 82% of the patients, the response was satisfactory in 12%, and unsatisfactory in 5%. Hyperuricemia per se did not offset the efficacy of the prophylactic regimen. Factors affecting the failure of the regimen were most frequently related to associated uncontrolled medical complications or intemperate habits of food or alcoholic beverages. Few patients were colchicine intolerant. No hematologic or renal toxic effects were observed with extended and regular ingestion of colchicine. At the dosage employed for prophylaxis 0.5 or 1.0 mg, colchicine was most likely involved in the suppression of chemotactic factors involving the synovial lining cells. There is no evidence of chromosomal aberration or infertility. Discontinuance of the prophylactic program may be attempted in any patient who has been free from recurrent attacks for several years, particularly in older patients with no medical complications.

Modulation of beta-adrenergic receptor by hydrocortisone in human polymorphonuclear leukocytes

We have examined the influence of isoproterenol and hydrocortisone on the cycle AMP content and lysosomal enzyme release from highly purified human polymorphonuclear leukocytes. It was found that isoproterenol, although a potent stimulus for cAMP accumulation in human lymphocytes, had only marginal effects on both cAMP content of PMN and enzyme release. Since corticosteroids have been reported to increase the response to beta-agonists in various tissues, it was considered that some of the anti-inflammatory potential of corticosteroids might be related to enhancing the response of PMN to beta-agonists. The influence of hydrocortisone on the response to isoproterenol was accordingly examined. It was found that hydrocortisone did in fact augment the isoproterenol-induced increase in cAMP content. In contrast to the potentiation of cAMP accumulation caused by hydrocortisone and isoproterenol together, the two agents produced only an additional inhibition of enzyme release. Since the inhibition of lysosomal enzyme release from human PMN did not closely reflect the changes observed in the cAMP content, a possible compartmentalization of intracellular cAMP is suggested.

Prolonged reduction in polymorphonuclear adhesion following oral colchicine

Polymorphonuclear leucocyte (PMN) function was studied in 7 healthy subjects before and after 5 mg of colchicine taken in divided doses over 24 hours. Mean adherence to nylon fibre colums fell from a pretreatment level of 51% to 33.6% by day 1, remained low (31.8%) at day 5, and returned to pretreatment levels only by about day 9. Random motility (agarose plate method) fell from 932 micrometers to 688 micrometers by day 1, but had returned to normal by day 5. Directed migration and the phagocytic index (opsonised Candida albicans method) were not affected by colchicine treatment. In this marked and prolonged reduction in PMN adhesion implies an influence on maturing PMN precursors in bone marrow. Adherence to nylon fibres may reflect in-vivo properties of PMN which are important in the pathogenesis of acute gouty arthritis.

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.

Synovial fluid beta 2 microglobulin and hydroxyproline fractions in rheumatoid arthritis and nonautoimmune arthropathies

Fourteen patients with classical and definite seropositive rheumatoid arthritis (RA), 5 patients with microcrystalline arthritis, and 7 patients with osteoarthrosis were studied with respect to markers of newly synthesised collagen (synovial NDOH pro levels); markers of connective tissue resorption (synovial DOH pro and NBH levels); markers of lymphoid tissue activity (synovial and plasma beta 2m levels). Higher amounts of NDOH pro in RA synovial fluid are compatible with the hypothesis of a local connective tissue production as suggested by Uitto et al. on basis of a higher protocollagen proline hydroxylase activity in RA synovial tissue. DOH pro and NBH do not differ significantly in synovial fluid from RA or gouty patients, but the correlations between these forms of OH pro and, respectively, synovial lymphocytes and polymorphonuclear leucocytes are indicative of different processes of connective tissue remodelling in the 2 conditions. Synovial beta 2m levels are a direct function of total synovial lymphocyte counts independently of the type of arthropathy being explored. The ratio of synovial to plasma beta 2m is systematically above unity in RA patients only.

The effect of various corticosteroids on the release of beta-glucuronidase from human leukocytes challenged with zymosan

Seven corticosteroids were tested for their effect on the release of beta-glucuronidase when human white cells were challenged with zymosan. Stabilization was noted in two areas of dilution with every steroid but destabilization occurred at high concentrations. However, those steroids that stabilized effectively at low concentrations were also those which were the most potent vasoconstrictors.

The antinflammatory effects of glucocorticosteroids. A brief review of the literature

The effects of glucocorticosteroids on immune and inflammatory responses are reviewed. The steroids seem to change the number or function of cell receptors for regulating agents, so that in areas of inflammation: (a) blood vessels dilate less, (b) lymphocytes proliferate less, (c) all leukocytes infiltrate less, (d) macrophages become less activated (digesting and secreting less), and (e) fibroblasts produce less collagen and ground substance. In addition, the corticosteroids seem to alter the response of cells to various signals from their receptors by affecting the prostaglandin system, cyclic nucleotides, and perhaps other internal mediators.

The Arthus reaction in rats, a possible test for anti-inflammatory and antiheumatic drugs

The Arthus reaction is an immunologically induced inflammatory response characterized by immune complex deposition, complement fixation, polymorphonuclear leukocyte infiltration and tissue damage. Many of these same pathological tissue alterations are found in the lesions of rheumatoid arthritis (RA). The similarities between the reversed passive Arthus reaction (RPAR) and RA led us to investigate the usefulness of the RPAR in the search for new antirheumatic agents. The RPAR was elicited in the skin of rats using chicken ovalbumin and the IgG fraction of rabbit anti-ovalbumin. Paramethasone, hydrocortisone, indomethacin, pirprofen, sulfinpyrazone, thalidomide and theophylline all gave significant inhibition of the RPAR. Ibuprofen, naproxen, cyprohepatadine and cromolyn sodium were inactive, while phenylbutazone and ASA exhibited a dose-dependent effect. The data show that the Arthus reaction, which is the result of the complex interaction of many factors, can be affected either generally or selectively at different time intervals by various therapeutic agents. The RPAR in rats may prove useful in detecting new therapeutic agents for the treatment of RA.

Colchicine-estrogen interactions

Colchicine does not block estrogen-induced recognition of uterine blood vessel surface by eosinophils, but interfers with their migration through endothelial lining and therefore blocks estrogen-induced uterine eosinophilia and edema.

Destruction of sensitized erythrocytes by human monocytes in vitro: effects of cytochalasin B, hydrocortisone and colchicine

The purpose of this study was to characterize the destruction of sensitized erythrocytes by human blood monocytes in vitro. The incubation in vitro of human monocytes with 51Cr-labelled human erythrocytes sensitized with IgG rhesus alloantibodies anti-D (EAIgG anti-D) resulted in release of 51Cr from the erythrocytes (lysis) as well as uptake of 51Cr-labelled erythrocytes by the monocytes (phagocytosis). The lysis of EAIgG anti-D by monocytes was not dependent on phagocytosis, because cytochalasin B, which inhibited phagocytosis of EAIgG, enhanced lysis. In contrast, hydrocortisone and colchicine inhibited lysis, but had no effect on phagocytosis. These agents did not affect binding of EAIgG anti-D to monocytes. The effect of these agents on lysis corresponded to their effect on release of lysosomal enzymes by monocytes. The release of lysosomal enzymes, when induced by EAIgG anti-D, was, likewise, enhanced by cytochalasin B and inhibited by hydrocortisone and colchicine. A significant correlation was found between lysosomal enzyme release and lysis. Together, these results strongly suggest that lysosomal enzymes, released by the monocytes when incubated with anti-D-sensitized erythrocytes, are responsible for the cytotoxic activity of these cells towards sensitized erythrocytes. The action of these enzymes only occurs over a short range, probably at the site of attachment of the erythrocyte, because only erythrocytes that were bound to the monocytes were lysed. The finding of other investigators that removal of monocytes from suspensions of human mononuclear leucocytes results in a strong reduction in the cytotoxic activity of these leucocytes towards sensitized erythrocytes in vitro. was confirmed.

Mechanisms of the immunosuppressive and anti-inflammatory effects of glucocorticosteroids

Corticosteroids have multifaceted effects on various phases of inflammatory and immunological activity. These include effects on vascular and tissue responses, effects on the movement or traffic of inflammatory or immunologically reactive cells, direct effects on functional capabilities of cells, and direct or indirect effects on various soluble factors mediating inflammation or immunologic activity. It is clear that there is a differential sensitivity of various populations and subpopulations of cells to the corticosteriod modulation of cellular kinetic patterns, cellular interactions, and functional capabilities. In general, corticosteroids have a much greater and more obvious effect on the traffic and kinetics than on the functional properties of cells involved in inflammation and immunologic activity. Hypotheses concerning the precise mechanisms of many of these effects have been proposed, but still await verification and possibly amplification.

Effect of auranofin, a new antiarthritic agent, on immune complex-induced release of lysosomal enzymes from human leukocytes

Auranofin, an oral chrysotherapeutic agent effective in the treatment of rheumatoid arthritis (RA), was found to be a potent, noncytotoxic inhibitor of IgG-RF immune complex-induced lysosomal enzyme release (LER) from human leukocytes. At a concentration of 1 microg Au/ml (5 microM), auranofin produced a marked reduction in beta-glucuronidase (100%), acid phosphatase (88%), and lysozyme (72%) release. In contrast, gold sodium thiosulfate (GST, an injectable gold compound) had no inhibitory activity on LER at equivalent gold concentrations (i.e., 1 microg Au/ml) and only modest activity (less than 36% inhibition) at concentrations as high as 40 microg Au/ml. The 50% inhibitory dose (LD50) of auranofin on LER was calculated to be 3-4 microM (0.6-0.8 microg Au/ml). Blood gold levels in auranofin-treated RA patients were found to be within the range required for in vitro inhibition of LER, and correlated with decreases in IgG, RF titers, and IgG-RF immune-complex formation in vitro. These results suggest that the therapeutic action of auranofin may be caused, at least in part, by inhibition of LER and/or decreases in immune-complex formation.

Role of microtubule assembly in lysosomal enzyme secretion from human polymorphonuclear leukocytes. A reevaluation

The dose-related inhibition by colchicine of both lysosomal enzyme release and microtubule assembly was studied in human polymorphonuclear leukocytes (PMN) exposed to the nonphagocytic stimulus, zymosan-treated serum (ZTS). Cells were pretreated with colchicine (60 min, 37 degrees C) with or without cytochalasin B (5 microng/ml, 10 min) and then stimulated with ZTS (10%). Microtubule numbers in both cytochalasin B-treated and untreated PMN were increased by stimulation and depressed below resting levels in a dose-response fashion by colchicine concentrations above 10(-7) M. These concentrations also inhibited enzyme release in a dose-response fashion although the inhibition of microtubule assembly was proportionately greater than the inhibition of enzyme release. Other aspects of PMN morphology were affected by colchicine. Cytochalasin B-treated PMN were rounded, and in thin sections the retracted plasma membrane appeared as invaginations oriented toward centrally located centrioles. Membrane invaginations were restricted to the cell periphery in cells treated with inhibitory concentrations of colchicine, and the centrioles and Golgi apparatus were displaced from their usual position. After stimulation and subsequent degranulation, the size and number of membrane invaginations greatly increased. They remained peripheral in cells pretreated with greater than 10(-7) M colchicine but were numerous in the pericentriolar region in cells treated with less than 10(-7) M. Similarly, untreated PMN that were permitted to phagocytose immune precipitates had many phagosomes adjacent to the centriole. After colchicine treatment, phagosomes were distributed randomly, without any preferential association with the centrioles. These data suggest that microtubules are involved in maintaining the internal organization of cells and the topologic relationships between organelles and the plasma membrane.

Effect of indomethacin and related drugs on the calcium ion-dependent secretion of lysosomal and other enzymes by neutrophil polymorphonuclear leucocytes in vitro

1 Rabbit isolated peritoneal neutrophil polymorphonuclear leucocytes were depleted of calcium by exposure for 1 h to calcium-free bathing fluid at 4 degrees C. 2 Addition of calcium ions to the previously calcium-depleted calls during incubation at 37 degrees C stimulated the release of beta-glucuronidase and of lysozyme but not of lactate dehydrogenase. 3 Low concentrations of indomethacin, flufenamate or salicylate, such as those which occur in the blood plasma after therapeutic doses of these drugs, selectively inhibited the calcium-induced release of beta-glucuronidase. The slight release of this enzyme which occurred in the absence of added calcium ions was not altered by these drugs, neither was the release of lactate dehydrogenase. 4 Release of lysozyme was inhibited by low concentrations of salicylate, amidopyrine or oxyphenbutazone, independent of the presence or absence of calcium ions. 5 Chloroquine, hydrocortisone or colchicine did not alter the release of leucocyte enzymes.

Glucocorticosteroid inhibition of nonphagocytic discharge of lysosomal enzymes from human neutrophils

Glucocorticosteroids and mineralocorticosteroids were tested for their capacity to inhibit the nonphagocytic discharge of two lysosomal enzymes--a cartilage matrix-degrading neutral protease and beta-glucuronidase--from highly purified human neutrophils. Lysosomal enzyme discharge from neutrophils adherent to nonphagocytizable, immobilized, heat-aggregated IgG was inhibited by the four glucocorticosteroids--methylprednisolone sodium succinate, triamcinolone acetonide hemisuccinate, para methasone acetate, and hydrocortisone sodium succinate. These glucocorticoids also inhibited zymosan-induced release of beta-glucuronidase from neutrophils that had been pretreated with cytochalasin B in order to completely prevent the onset of phagocytosis. Inhibition by the glucocorticoids of lysosomal enzyme discharge provoked by a soluble divalent cation ionophore was also observed. Neither desoxycorticosterone acetate nor aldosterone hemisuccinate, two mineralocorticosteroids, inhibited lysosomal enzyme release. Similarly, the salt moieties of some of the steroids tested, such as sodium succinate and sodium acetate, failed to elicit an effect on enzyme release. Therefore interference with lysosomal enzyme discharge was restricted to the glucocorticosteroid ring structure. Because interference either with the adherence of neutrophils to immune reactants or with the activities of the discharged lysosomal enzymes by the glucocorticoids could be interpreted as inhibition of lysosomal enzyme release, steroidal effects on these parameters were examined. None of the glucocorticoids tested elicited any significant effects on neutrophil adherence or lysosomal enzyme activity. Thus it appears that glucocorticosteroids are capable of inhibiting directly the nonphagocytic discharge of lysosomal enzymes from human neutrophils.

Phospholipid metabolism and lysosomal enzyme secretion by leukocytes. Effects of dibutyryl cyclic adenosine 3':5'-monophosphate and ATP

The effects of dibutyryl cyclic adenosine 3':5'-monophosphate and ATP on isotope incorporation into phospholipids and the release of beta-glucuronidase into the extracellular medium were studied in polymorphonuclear leukocytes from guinea pig peritoneal exudates. Exogenous dibutyryl cyclic adenosine 3':5'-monophosphate (0.1--1.0 mM) reduced beta-glucoronidase release induced by cytochalasin B in the absence of inert particles. It selectively inhibited 32Pi incorporation into phosphatidic acid and the phosphoinositides and the incorporation of myo-[2-3H]inositol into the phosphoinositides. Added ATP (0.1--1.0 MM), but not other nucleotides, was found to potentiate beta-glucuronidase release provoked by cytochasin B, but it impaired the labeling of the phosphoinositides by myo-[2-3H]inositol. The mechanism of the inhibition the isotope incarparation into these acidic phospholipids by the two mucleotides has not been defined. Dibutyryl cyclic adenosine 3':5'-monophosphate at 2--4 mM concentration was not found to appreciably alter the incorporation of [gamma-32P]ATP into phosphatidic acid, phosphatidylinositol, diphosphoinositide, and triphosphoinositide.

The effect of anti-inflammatory compounds on the biochemical changes in the Arthus reaction

The effect of anti-inflammatory drugs on the biochemical changes in the Arthus reaction have been studied and correlated to changes in the pathology of the reaction. In the Arthus reaction all the non-steroidal anti-inflammatory drugs inhibited the migration of cells into the lesion and reduced the lysosomal enzyme concentration at the Arthus site. The steroids did not inhibit the cellular inflitration or the total lysosomal enzyme concentration in the skin but did reduce the concentration of cathepsin D in the oedema fluid. In addition, prednisolone and, to a lesser extent, hydrocortisone reduced the degree of oedema formation. The results suggest that non-steroidal anti-inflammatory drugs inhibit the Arthus reaction by reducing the cellular infiltration whereas anti-inflammatory steroids act by preventing these cells secreting their lysosomal enzymes and thus causing tissue damage.

Influence of corticosteroids on human polymorphonuclear leukocyte function in vitro : Reduction of lysosomal enzyme release and superoxide production

In an experimental system in which phagocytosis or adherence of cells to surfaces were excluded as variables, we have investigated the possibility that corticosteroids may inhibit release of lysosomal constituents from viable human polymorphonuclear leukocytes into the extracellular environment. Release ofΒ-glucuronidase and lysozyme from cytochalasin B-treated cells exposed to serum-treated zymosan, heat-aggregated human IgG, and the complement component C5a was significantly reduced by pretreatment with hydrocortisone sodium succinate and methylprednisolone sodium succinate (5×10(-4) M). Both steroids also reduced superoxide production by these cells. These in vitro studies provide evidence that corticosteroids influence membrane-dependent responses of intact, viable polymorphonuclear leukocytes to immune reactants. Inhibition of these responses (lysosomal enzyme release, superoxide production) may explain, in part, both the antiinflammatory actions of steroids and their deleterious effects on host defenses.

The effect of steroids on differentiation and function of cultured, mononuclear cells

When monocytes had differentiated to macrophages during 8 days of culture in vitro without being exposed to steroids, neither the engulfement nor the digestion step of phagocytosis was found to be influenced by cortisol or the other steroids tested. This indicates that cortisol has no direct effect on the phagocytic function of macrophages in doses below 10(-1) mg/ml. Continuous exposure to cortisol during the period of differentiation resulted in a dose dependent inhibition of the differentiation of monocytes to macrophages. Testosterone, deoxycorticosterone and tetrahydrocortisol in concentration of 10(-1) mg/ml, tested in the same way were found to be toxic to the cells. In lower concentrations, however, these steroids were found to have no effect on the cultured cells. The impaired differentiation of monocytes is suggested as an additional explanation of the reduced number of macrophages appearing at the site of inflammation during cortisol treatment.

Effects of steroid hormones on human polymorphonuclear leukocyte lysosomes

Lysosomal membrane stabilization has been proposed as a mechanism for the anti-inflammatory action of corticosteroid hormones. This hypothesis was based on studies with liver organelles. We studied the action of steroids on intact lysosomes isolated from human peripheral blood polymorphonuclear (PMN) leukocytes. Both androstenedione and progesterone, 10(-3)-10(-5) M, caused leakage of acid hydrolase markers from these organelles, thus resembling their effects on liver lysosomes. But none of the anti-inflammatory steroids tested protected organelle membranes from either detergent lysis (Triton X-100) or heat incubation (37 degrees C, 90 min). Hydrocortisone (HC), HC sodium succinate, HC acetate, HC hemisuccinate, prednisone, and dexamethasone were without detectable stabilizing activity at concentrations of 10(-3)-5 x 10(-8) M. Release of the lysosomal marker, beta-glucuronidase, was not retarded by any of the compounds studied. In addition, PMN leukocyte lysosomes isolated from human volunteers receiving prednisolone were not more stable than control organelles, nor did serum from steroid-treated humans protect intact lysosomes from detergent lysis. Variations in cholesterol and phospholipid contents of liver and PMN leukocyte lysosome membranes could possibly account for the different reactivity to corticosteroids observed. We believe that the anti-inflammatory activity of adrenal corticosteroids can best be explained by their inhibitory effects on cellular metabolism rather than by their direct interaction with lysosomal membranes.