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Biomedical subjects

M Baggiolini

Publications and source records attributed to M Baggiolini.

At least 217 records · Page 12Linked to original sources
PubMed1982

[Phagocytes and phagocytosis 100 years after Metchnikoff. A current picture of the neutrophil leukocyte].

The observation of the amoebocytes of primitive organisms led ELIAS METSCHNIKOFF in 1882 to the idea that blood phagocytes--neutrophilic leukocytes in particular--could constitute an anti-microbial defense system. This was the beginning of the phagocyte theory which METSCHNIKOFF developed over many years and which in essence is still valid. The author sets out to provide an updated view of the neutrophil. Circulating neutrophils are end-cells. They develop in the bone marrow by a relatively long maturation process during which the characteristic azurophil and specific granules are formed. The granules are stored organelles. The azurophil granules contain microbicidal enzymes, i.e. myeloperoxidase and lysozyme, together with a large number of acid hydrolases and neutral proteases. The specific granules contain lysozyme, a collagenase, lactoferrin and transcobalamines. By subcellular fractionation a third kind of storage organelle has recently been found which is characterized by its gelatinase content. Circulating neutrophils are activated on microbial invasion--first in the blood, by chemotactic factors formed at the site of infection, and subsequently by the microbes themselves which are phagocytosed by the immigrating neutrophils. Chemotactic factors lead to directed migration and induce the secretion of enzymes which presumably facilitate this process. Phagocytosis results in the mobilization of neutrophil products in large quantities. The contact between the cell and the microorganism activates in the neutrophil membrane an oxidase which produces superoxide, and a phospholipase which releases arachidonic acid. The latter is then oxidized by cyclooxygenase and lipoxygenase. There is also massive liberation of enzymes from all three storage compartments. The production of superoxide is the essential process for the killing of a large variety of microorganisms.

Allergy and Immunology↗
PubMed1982

Partial purification of collagenase and gelatinase from human polymorphonuclear leucocytes. Analysis of their actions on soluble and insoluble collagens.

The separation and further purification of human polymorphonuclear-leucocyte collagenase and gelatinase, using modifications of the method of Cawston & Tyler [(1979) Biochem J. 183, 647-656], are described. The final preparations yielded collagenase of specific activity 260 units/mg and gelatinase of specific activity 13 000 units/mg. Gelatinase was purified to apparent homogeneity in a latent form, and analysis of the activation of 125I-labelled latent enzyme by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis and gel-filtration techniques suggested that no peptide material was lost on conversion into the active form. The purified natural inhibitors alpha 2-macroglobulin, tissue inhibitor of metalloproteinases ('TIMP') and amniotic-fluid inhibitor of metalloproteinases all inhibited the two polymorphonuclear-leucocyte metalloproteinases, but the last two inhibitors were slow to act and complete inhibition was difficult to attain. Collagenase degraded soluble types I and III collagen equally efficiently, but soluble type II collagen less well. Gelatinase alone had little activity on these substrates, although it enhanced the action of collagenase. Gelatinase was capable of degrading soluble types IV and V collagen at 25 degrees C, whereas collagenase was only active at higher temperatures when the collagens were susceptible to trypsin activity. By using tissue preparations of insoluble collagens (type I, II or IV) the activity of leucocyte collagenase was low and gelatinase activity was negligible, as measured by the solubilization of hydroxyproline-containing material. The two enzymes together were two or three times more effective in the degradation of these insoluble collagens.

Animals↗
PubMed1982

Phagocytosis-stimulated macrophages. Production of prostaglandins and SRS-A, and prostaglandin effects on macrophage activation.

Quiescent mouse peritoneal macrophages which phagocytose, and which respond to phagocytosis with a sudden elevation in hexose monophosphate shunt activity, immediately release into the medium oxygen metabolites, arachidonic acid oxygenation products, and lysosomal hydrolases. Such cells subsequently differentiate and acquire the properties of inflammatory macrophages. The latter process appears to be under the control of prostaglandin E2 and possibly other cyclooxygenase products which are formed as a consequence of phagocytosis and seem to act as feed-back inhibitors.

Animals↗
PubMed1982

Phagocytosis of mast cell granules by mononuclear phagocytes, neutrophils and eosinophils during anaphylaxis.

The phagocytosis by mononuclear phagocytes, neutrophils and eosinophils of mast cell granules which are released in the course of anaphylactic reactions was studied in the rat. Degranulation of rat peritoneal mast cells was induced either in vivo or in vitro after passive sensitization with homologous reaginic antiovalbumin serum by challenge with the antigen. The approximate extent of degranulation was assessed by determining histamine release. The anaphylactic reaction was stopped by fixation with glutaraldehyde and the cells were examined by electron microscopy. Phagocytosis was quantified in randomly selected thin section at the magnification of 1,800. Rapid and extensive phagocytosis of mast cell granules was observed both in vivo and in vitro. About one third of the mononuclear phagocytes and between 30 and 53% of the neutrophils present were engaged in phagocytosis and usually contained several mast cell granules. Phagocytosis by eosinophils was less prominent, both with respect to the proportion of phagocytosing cell (10-23%) and to the number of mast cell granules per cell profile. Examination of large numbers of cells indicates that the uptake process is highly efficient since both condensed and already disaggregated granule bodies were seen to adhere to the phagocytes and were taken up rapidly and without the need for opsonization. In the neutrophils, extensive fusion of azurophil granules (as evidenced by peroxidase cytochemistry) with phagosomes containing mast cell granules was observed. Occasionally, mast cell granules were seen within disrupted vacuoles, which could result from the swelling of the granule matrix following engulfment. The result of this study indicate that mononuclear and polymorphonuclear phagocytes have the capacity to scavenge important amounts of mast cell granule products released by anaphylaxis.

Anaphylaxis↗
PubMed1982

Release of gelatinase from a novel secretory compartment of human neutrophils.

Gelatinase is a metallo-proteinase that acts specifically on denatured collagen. In human neutrophils, this enzyme is localized in small, morphologically still unidentified storage organelles that are resolved from the specific and the azurophil granules upon subcellular fractionation by differential sedimentation. When neutrophils isolated from freshly drawn blood are exposed to soluble stimuli such as N-formyl-methionyl-leucyl-phenylalanine, zymosan-activated serum, phorbol myristate acetate, or the calcium ionophore A 23187, or are induced to phagocytose opsonized zymosan, they rapidly release gelatinase in large amounts (30-70% of the cellular content in 10 min). When neutrophils from donor blood, which had been stored for 24 h at 4 degrees C are used, extensive release even occurs without added stimuli by simply warming to 37 degrees C. Gelatinase release appears to occur by secretion because it is not dependent on phagocytosis. It is paralelled by the release of specific granule contents (vitamin B(12)-binding protein), but is more rapid and much more extensive. It is, however, dissociated from the discharge of azurophil granules (as assessed by beta-glucuronidase). In addition, it was found that gelatinase release does not depend on the activation of the respiratory burst, although the two responses are often observed in parallel. Release is not due to cell damage as the cytoplasmic enzyme lactate dehydrogenase is fully retained. The distinct subcellular distribution and kinetics of release of gelatinase reported in this paper uncover a novel, truly secretory compartment of human neutrophils, which is highly responsive to stimulation. Gelatinase and possibly other enzymes stored in this secretory organelle may be involved in the early events of neutrophil mobilization, the response to chemotactic signals and diapedesis.

Calcimycin↗
PubMed1981

Dissociation between the anti-anaphylactic and the anti-histaminic actions of ketotifen.

Ketotifen is a compound with strong anti-anaphylactic and anti-histaminic properties both in experimental mental animals and man. In this paper pharmacological experiments are presented which show that these two activities are independent. In the rat, the two actions of ketotifen differ markedly in their time course. The ability of ketotifen to prevent a passive cutaneous anaphylactic reaction is of short duration and is already abolished at times when the compound still fully prevents the cutaneous reaction to histamine. Two anti-histamines, clemastine and mepyramine, were compared with ketotifen. All three compounds prevented the wheal and flare induced by intracutaneous administration of histamine, but only ketotifen also prevented passive cutaneous anaphylaxis. Accordingly, concomitant administration of the anti-histamine clemastine with ketotifen resulted in enhanced histamine-blocking effects but did not influence the anti-anaphylactic action of ketotifen. Finally, clemastine and mepyramine differed from ketotifen in their activities in a model of anaphylactically-induced bronchospasm. Ketotifen prevented the bronchospasm, dyspnea and respiratory arrest in dose-dependent fashion, while the two reference anti-histamines were virtually inactive.

Airway Resistance↗
PubMed1981

Effects of cyclooxygenase inhibitors and prostaglandin E2 on macrophage activation in vitro.

The effect of the cyclooxygenase inhibitors, indomethacin and diclofenac, and of PGE2 on either resting or stimulated macrophages was investigated. Peritoneal macrophages were obtained from untreated mice and cultured for 10 days. Macrophage activation was induced by zymosan phagocytosis and was monitored by testing for plasminogen activator secretion and the cellular levels of lactate dehydrogenase, beta-glucuronidase and alkaline phosphodiesterase I. It was found that cyclooxygenase inhibitors activate resting macrophages and enhance the degree of activation obtained after zymosan phagocytosis. Addition of exogenous PGE2, on the other hand, had the opposite effect, it suppressed activation induced either by cyclooxygenase inhibitors, phagocytosis or a combination of both. Cyclooxygenase inhibitors and PGE2 did not affect the hexose monophosphate shunt activity of resting macrophages and had only a minor effect on the respiratory burst occurring during zymosan phagocytosis. It appears, therefore, that the observed changes in the state of activation of the macrophages are not related to hexose monophosphate shunt activity. The described effects suggest that PGE2 and possibly other cyclooxygenase products may function as inhibitory feed-back regulators of macrophage activation.

Animals↗
PubMed1981

2,3-Dihydrobenzofuran-2-ones: a new class of highly potent antiinflammatory agents.

A series of 2,3-dihydrobenzofuran-2-one analogues of the mold metabolite wortmannin, which is a powerful antiinflammatory compound, was synthesized. Most of these compounds were tested for their ability to inhibit the carrageenin paw edema and the adjuvant-induced arthritis of the rat and for their ability to inhibit prostaglandin synthesis in vitro. Indomethacin and diclofenac were used as references. The results show that compounds bearing an alkyl or aryl group in position 6 and an additional substituent, preferably chlorine, in position 5 are very powerful antiinflammatory agents and inhibitors of prostaglandin synthesis. The most active among these compounds, 5-chloro-6-cyclohexyl-2,3-dihydrobenzofuran-2-one, was significantly more potent than diclofenac in all testing models, more powerful than indomethacin in inhibiting acute inflammation and prostaglandin synthesis, and somewhat less potent than the latter compound in the adjuvant arthritis model.

Animals↗
PubMed1981

Defective Aspergillus killing by neutrophil leucocytes in a case of systemic aspergillosis.

A persistent defect of Aspergillus killing was observed in the neutrophils of a 6-year-old patient with a systemic A. fumigatus infection which was highly refractory to anti-mycotic therapy. Aspergillus phagocytosis in vitro was normal, but nearly 80% of the ingested organisms (versus 30% in the controls) survived intracellularly during the 2-hr assay period. The patient's neutrophils showed a subnormal frequency of nitroblue tetrazolium reduction and a subnormal hexose monophosphate shunt activation in response to phagocytosis. The metabolic responsiveness, however, was clearly superior to that of chronic granulomatous disease neutrophils tested for comparison. The immune status of the patient and the following properties of his neutrophils were found to be normal: random and chemotactic motility, killing of S. aureus and C. albicans, and the contents of several granula enzymes. Our findings suggest the existence of neutrophil factors or functions which are required for killing Aspergillus, but not S. aureus and C. albicans.

Aspergillosis↗
PubMed1980

The latent collagenase and gelatinase of human polymorphonuclear neutrophil leucocytes.

Two metallo-proteinases of human neutrophil leucocytes, collagenase and gelatinase, were studied. Collagenase specifically cleaved native collagen into the TCA and TCB fragments, whereas gelatinase degraded denatured collagen, i.e. gelatin, and the TCA fragments produced by collagenase. On subcellular fractionation by zonal sedimentation, collagenase was found to be localized in the specific granules, separate from gelatinase, which was recovered in smaller subcellular organelles known as C-particles. Neither enzyme was present in the azurophil granules, which contain the two major serine proteinases of neutrophils, elastase and cathepsin G. Collagenase and gelatinase were separated by gel filtration from extracts of partially purified granules. Both enzymes were found to occur in latent forms and were activated either by trypsin or by 4-aminophenylmercuric acetate. Gelatinase was also activated by cathepsin G, which, however, destroyed collagenase. Both enzymes were destroyed by neutrophil elastase. Activation resulted in a decrease by 25 000 in the apparent mol. wt. of both latent metallo-proteinases.

Collagen↗
PubMed1980

Induction of plasminogen activator secretion in macrophages by electrochemical stimulation of the hexose monophosphate shunt with methylene blue.

Resident peritoneal macrophages were obtained from untreated mice and were cultured in medium 199 with or without 5% acid-treated fetal bovine serum. Three hours after harvesting, redox compounds--i.e., methylene blue, methyl viologen, or nitro blue tetrazolium--were added to the cultures of adherent cells. After 1 hr, the cells were washed and culturing was continued in the absence of redox compounds. The effects of the redox compounds were tested by assaying for hexose monophosphate (HMP) shunt activity and for plasminogen activator secretion, and the results were compared with the effects induced by phagocytic stimuli. Methylene blue caused a concentration-dependent stimulation of the HMP shunt, whereas methyl viologen and nitro blue tetrazolium were ineffective. Shunt stimulation by methylene blue was followed, after a lag of 2-4 days, by plasminogen activator secretion. The rate of secretion was dependent on the methylene blue concentration used. Methyl viologen and nitro blue tetrazolium were again ineffective, whereas phagocytosis of zymosan or sheep erythrocytes, which stimulates the HMP shunt, induced plasminogen activator secretion at rates similar to those induced by methylene blue. These results add further evidence to our hypothesis that the HMP shunt-dependent metabolic burst is involved in macrophage activation. Because methylene blue mimics the action of zymosan it appears that shunt stimulation by itself initiates the activation process independently of phagocytosis.

Animals↗
PubMed1979

Cellular mechanisms of proteinase release from inflammatory cells and the degradation of extracellular proteins.

Neutrophils and macrophages produce, store and release large amounts of various acid and neutral proteinases. The two main proteinases of neutrophils are elastase and cathepsin G. They are localized in the azurophil granules, together with proteinase 3 and the acid cathepsins B and D. In addition neutrophils contain collagenase in the specific granules, acid proteinases in the C-particles and plasminogen activator in organelles with the characteristics of secretory vesicles. The granule-bound proteinases are released during phagocytosis while plasminogen activator is apparently secreted. In macrophages, the acid hydrolases are bound to lysosomes while the neutral proteinases are confined to secretory vesicles. The main mechanism of enzyme release in macrophages is secretion. Lysosomal hydrolases are also released by phagocytosis. Enzyme secretion is a characteristic property of activated or inflammatory macrophages. Macrophages become activated after phagocytosis of certain particles and the metabolic burst appears to be an initial event in the activation process. The action of neutrophils and of purified elastase or plasmin on cartilage was tested. These experiments indicate that neutrophil-mediated degradation of cartilage proteoglycans is largely dependent on elastase.

Animals↗