Macrophage deactivation by interleukin 10

Recombinant mouse interleukin 10 (IL-10) was exceedingly potent at suppressing the ability of mouse peritoneal macrophages (m phi) to release tumor necrosis factor alpha (TNF-alpha). The IC50 of IL-10 for the suppression of TNF-alpha release induced by 0.5 microgram/ml lipopolysaccharide was 0.04 +/- 0.03 U/ml, with as little as 1 U/ml suppressing TNF-alpha production by a factor of 21.4 +/- 2.5. At 10 U/ml, IL-10 markedly suppressed m phi release of reactive oxygen intermediates (ROI) (IC50 3.7 +/- 1.8 U/ml), but only weakly inhibited m phi release of reactive nitrogen intermediates (RNI). Since TNF-alpha is a T cell growth and differentiation factor, whereas ROI and RNI are known to inhibit lymphocyte function, it is possible that m phi exposed to low concentrations of IL-10 suppress lymphocytes. m phi deactivated by higher concentrations of IL-10 might be permissive for the growth of microbial pathogens and tumor cells, as TNF-alpha, ROI, and RNI are major antimicrobial and tumoricidal products of m phi. IL-10's effects on m phi overlap with but are distinct from the effects of the two previously described cytokines that suppress the function of mouse m phi, transforming growth factor beta and macrophage deactivation factor. Based on results with neutralizing antibodies, all three m phi suppressor factors appear to act independently.

Eradication of methicillin-resistant Staphylococcus aureus vaginitis with mupirocin

We report the case of a 54-year-old, quadriplegic woman with a methicillin-resistant Staphylococcus aureus (MRSA) vaginal infection. After failing a five-day course of intravenous vancomycin therapy, the patient was treated for ten days with mupirocin ointment applied intravaginally twice daily, which resulted in eradication of the infection. This report details a novel approach in treating MRSA vaginal infections.

Complementary DNA sequence of human neutrophil azurocidin, an antibiotic with extensive homology to serine proteases

Human neutrophils contain in their azurophil granules four antibiotic proteins with extensive homology to serine proteases, collectively termed serprocidins. Azurocidin is the only member of the group that lacks proteolytic activity. Using a monospecific antibody, we isolated from human bone marrow a cDNA encoding the complete azurocidin protein in its mature form, along with an N-terminal 24 residue hydrophobic peptide. The N-terminal third of the mature protein sequence contains a cluster of positively charged amino acid residues, many of which are predicted to be surface exposed. The primary sequence is highly homologous to elastase, proteinase 3, cathepsin G, T-cell granzymes and other serine proteases. However, azurocidin has Gly for Ser and Ser for His substitutions in the catalytic triad. Southern blot analysis of human genomic DNA suggests the existence of a single azurocidin coding sequence.

Mechanisms and modulation of macrophage activation

In the two decades following the discovery that macrophages can be activated by cytokines, there have been four major advances in our understanding of this phenomenon: (i) the identification of two biochemically defined, cytokine-inducible antimicrobial pathways, the enzymatic generation of superoxide and the enzymatic generation of nitric oxide; (ii) the identification of individual cytokines of known amino acid sequence capable of inducing these antimicrobial pathways and enhancing macrophage antimicrobial function; (iii) the demonstration of the utility of macrophage activating factors in the prevention and treatment of infectious diseases in man; and (iv) the discovery of the phenomenon of macrophage deactivation, together with the identification of several macrophage deactivating cytokines. This review briefly surveys each of these points, with emphasis on the regulation of production of the reactive oxygen intermediates and reactive nitrogen intermediates by two distinct but comparably suppressive cytokines, macrophage deactivation factor (MDF) and transforming growth factor-beta (TGF-beta).

The mode of action and clinical pharmacology of gliclazide: a review

Gliclazide is a sulphonylurea drug with an intermediate half-life of around 11 hours. It is extensively metabolised, and renal clearance accounts for only 4% of total drug clearance. The molecule contains an azabicyclo-octyl group which confers special properties on the basic sulphonylurea moiety. Gliclazide stimulates insulin secretion through the beta cell sulphonylurea receptor, and possibly through a direct effect on intracellular calcium transport. It specifically improves the abnormal first phase insulin release in type 2 diabetes, and also has an effect on the second phase. This pattern of insulin release is thought to explain the lower incidence of hypoglycaemic episodes and weight gain compared with some other sulphonylureas. There is also a reduction in hepatic glucose production and improvement in glucose clearance, without changes in insulin receptors. This suggests a possible post-receptor effect on insulin action, perhaps by stimulation of hepatic fructose-2,6-bisphosphatase and muscle glycogen synthase. Gliclazide reduces platelet adhesion, aggregation and hyperactivity and increases fibrinolysis. These actions, thought to be independent of its hypoglycaemic activity, may make gliclazide useful in halting the progression of diabetic microangiopathy.

Pilot trial of selective decontamination for prevention of bacterial infection in an intensive care unit

Selective decontamination of the oropharynx and gastrointestinal tract with nonabsorbable antimicrobials and sucralfate, a stress ulcer prophylactic that maintains the normal gastric acid bacterial barrier, were compared for prevention of pneumonia in a cardiac surgery intensive care unit. Over 8 months, 51 patients received selective decontamination and 56 received sucralfate. The selective decontamination regimen included polymyxin, gentamicin, and nystatin given as an oral paste and as a solution; patients also received standard antacid or histamine2 blocker stress ulcer prophylaxis. Patients in the selective decontamination group had significantly less colonization of the oropharynx and stomach by gram-negative bacilli (12% vs. 55%, P less than .001), significantly fewer infections due to gram-negative bacilli (6% vs. 20%, P = .02), and fewer infections overall (12% vs. 27%, P = .04). There was one episode of pneumonia in the selective decontamination group and five in the sucralfate group. Mortality and length of stay did not differ between the groups, but those receiving selective decontamination had less than one-third as many days of systemic antibiotic therapy with no increase in colonization or infection with resistant gram-negative bacilli. Thus, selective decontamination appeared to reduce both extrapulmonary and pulmonary infections.

Cloning of cDNA for proteinase 3: a serine protease, antibiotic, and autoantigen from human neutrophils

Closely similar but nonidentical NH2-terminal amino acid sequences have been reported for a protein or proteins in human neutrophils whose bioactivities is/are diverse (as a serine protease, antibiotic, and Wegener's granulomatosis autoantigen) but that share(s) several features: localization in the azurophil granules, a molecular mass of approximately 29 kD, reactivity with diisopropylfluorophosphate, and the ability to degrade elastin. We previously purified one such entity, termed p29b. Using a monospecific antibody, we have cloned from human bone marrow a cDNA encoding the complete p29b protein in its mature form, along with pre- and pro-sequences. The predicted amino acid sequence agrees closely with the NH2-terminal sequence obtained previously from purified p29b, as well as with sequences newly obtained from CNBr fragments. The primary structure is highly homologous to elastase, cathepsin G, T cell granzymes, and other serine proteases, and shares both the catalytic triad and substrate binding pocket of elastase. Hybridization of the full-length cDNA with restriction enzyme digests of human genomic DNA revealed only one fragment. This suggests that the closely related species described previously are the same, and can be subsumed by the term used for the first-described activity, proteinase 3. Proteinase 3 is more abundant in neutrophils than elastase and has a similar proteolytic profile and specific activity. Thus, proteinase 3 may share the role previously attributed to neutrophil elastase in tissue damage, and has the potential to function as an antimicrobial agent.

Widespread intradermal accumulation of mononuclear leukocytes in lepromatous leprosy patients treated systemically with recombinant interferon gamma

Intradermal administration of recombinant interferon gamma (rIFN-gamma) to lepromatous leprosy patients has converted the local histology toward a tuberculoid pattern. However, such changes have been confined to the site of injection. In contrast, in the present study, marked, intradermal accumulation of CD3+, CD4+, CD8+, and CD1a+ T cells and Leu-M5+ mononuclear phagocytes was induced at a distance from the sites of administration, in a dose-dependent manner, by 10 daily intramuscular injections of 10-30 micrograms rIFN-gamma/m2. Mononuclear cell infiltration began within 3 d of onset of rIFN-gamma therapy and persisted at least 8 wk. Intramuscular administration of rIFN-gamma to lepromatous patients receiving concurrent chemotherapy can safely induce widespread histologic features of an upgrading reaction.

Tumor necrosis factor and CD11/CD18 (beta 2) integrins act synergistically to lower cAMP in human neutrophils

The ability of neutrophils (PMN) to undergo a prolonged respiratory burst in response to cytokines such as tumor necrosis factor-alpha (TNF) depends on expression of CD11/CD18 (beta 2) integrins and interaction with matrix protein-coated surfaces (Nathan, C., S. Srimal, C. Farber, E. Sanchez, L. Kabbash, A. Asch, J. Gailit, and S. D. Wright. 1989. J. Cell Biol. 109:1341-1349). We tested the hypothesis that changes in cAMP mediate the joint action of cytokines and integrins. When plated on FBS- or fibrinogen-coated surfaces, PMN responded to TNF with a sustained fall in intracellular cAMP. This did not occur without TNF; in suspended PMN; in PMN treated with anti-CD18 mAb; or in PMN genetically deficient in beta 2 integrins. A preceding fall in cAMP appeared essential for TNF to induce a respiratory burst, because drugs that elevate cAMP blocked the burst if added any time before, but not after, its onset. Adenosine analogues and cytochalasins also block the TNF-induced respiratory burst if added before, but not after, its onset. Both also blocked the TNF-induced fall in cAMP. The effect of cytochalasins led us to examine the relationship between cAMP and actin reorganization. The same conditions that led to a sustained fall in cAMP led at the same time to cell spreading and the assembly of actin filaments. As with the respiratory burst, cAMP-elevating agents inhibited TNF-induced cell spreading and actin filament assembly if added before, but not after, spreading began. Thus, occupation of TNF receptors and engagement of CD18 integrins interact synergistically in PMN to promote a fall in cAMP. The fall in cAMP is closely related to cell spreading and actin reorganization. These changes are necessary for TNF to induce a prolonged respiratory burst. We conclude that integrins can act jointly with cytokines to affect cell shape and function through alterations in the level of a second messenger, cAMP.

Shedding of tumor necrosis factor receptors by activated human neutrophils

The capacity of human neutrophils (PMN) to bind tumor necrosis factor (TNF) was rapidly lost when the cells were incubated in suspension with agents that can stimulate their migratory and secretory responses. Both physiological (poly)peptides (FMLP, C5a, CSF-GM) and pharmacologic agonists (PMN, calcium ionophore A23187) induced the loss of TNF receptors (TNF-R) from the cell surface. Half-maximal loss in TNF-R ensued after only approximately 2 min with 10(-7) M FMLP at 37 degrees C, and required only 10(-9) M FMLP during a 30-min exposure. However, there were no such changes even with prolonged exposure of PMN to FMLP at 4 degrees or 16 degrees C. Scatchard analysis revealed loss of TNF-binding sites without change in their affinity (Kd approximately 0.4 nM) as measured at incompletely modulating concentrations of FMLP, C5a, PMA, or A23187. The binding of anti-TNF-R mAbs to PMN decreased in parallel, providing independent evidence for the loss of TNF-R from the cell surface. At the same time, soluble TNF-R appeared in the medium of stimulated PMN. This inference was based on the PMN- and FMLP-dependent generation of a nonsedimentable activity that could inhibit the binding of TNF to fresh human PMN or to mouse macrophages, and the ability of mAbs specific for human TNF-R to abolish inhibition by PMN-conditioned medium of binding of TNF to mouse macrophages. Soluble TNF-R activity was associated with a protein of Mr approximately 28,000 by ligand blot analysis of cell-free supernatants of FMLP-treated PMN. Thus, some portion of the FMLP-induced loss of TNF-R from human PMN is due to shedding of TNF-R. Shedding was unaffected by inhibitors of serine and thiol proteases and could not be induced with phosphatidylinositol-specific phospholipase C. Loss of TNF-R from PMN first stimulated by other agents may decrease their responsiveness to TNF. TNF-R shed by PMN may be one source of the TNF-binding proteins found in body fluids, and may blunt the actions of the cytokine on other cells.

Purification of macrophage deactivating factor

Macrophage deactivation factor (MDF) in P815 tumor cell-conditioned medium was assayed by its suppression of the ability of activated mouse peritoneal macrophages to release hydrogen peroxide. MDF displayed properties of a soluble protein(s) associated with both low (8-25,000) and high (greater than 450,000) Mr fractions. MDF was purified 6,140-fold by a seven-step procedure: extraction with acid-ethanol; precipitation with ether; and fractionation on gel filtration, anion-exchange, diphenyl reversed-phase and C4 reversed-phase HPLC columns, the last column twice. The final preparation contained two species: (a) a approximately 13,000 Mr band on reducing or nonreducing SDS-PAGE and on autoradiograms after radioiodination with chloramine T, and (b) a 66,000 Mr species ranging from approximately 5% to approximately 50% of the protein detectable by silver strain. The 66,000 Mr species was identified as albumin from its NH2-terminal amino acid sequence. However, no amino acid sequence could be obtained for the approximately 13,000 Mr species, either in fluid phase or after electroelution of the corresponding SDS-PAGE band. Thus, approximately 13,000 Mr MDF associates tightly with albumin through a variety of separation techniques, and may have a blocked NH2 terminus. Purified MDF afforded 50% inhibition of activated macrophage H2O2 releasing capacity at a concentration of 1-10 nM. Separation of MDF from most higher Mr moieties was associated with disproportionately small increases in specific activity, suggesting MDF might be partially inactivated by purification. As purified, MDF was approximately 1,000-fold less potent at deactivating macrophages than TGF-beta. Antibodies that neutralized the macrophage-deactivating effect of TGF-beta did not inhibit deactivation by MDF.

The epidemiology of Pseudomonas aeruginosa in oncology patients in a general hospital

Pseudomonas aeruginosa colonization and infection was studied over a 6-mo period in a 36-bed mixed general medical-oncology unit. We used selective media for serial surveillance cultures on 283 patients, the environment, and personnel. Twelve percent of patients were colonized on admission and 10% acquired P. aeruginosa. Using serotyping and multilocus enzyme electrophoresis, we identified 63 genetically distinctive strains; four prevalent strains accounted for 21% of isolates. Only 5 of 33 nosocomial acquisitions were due to horizontal transmission. Nine acquisitions were linked to environmental sources (e.g., sink surfaces), which often harbored antibiotic-resistant strains but posed a risk only to oncology patients. Although significant Pseudomonas infections occurred in only 11% of colonized patients, 63% of colonized severely neutropenic patients--predominantly those who had acquired the prevalent, often environmentally linked strains--developed infections. Thus, P. aeruginosa was a significant pathogen in oncology patients; typing by multilocus enzyme electrophoresis allowed the detection of important environmental sources.

Cytokine-induced respiratory burst of human neutrophils: dependence on extracellular matrix proteins and CD11/CD18 integrins

Human polymorphonuclear leukocytes (PMN) released large quantities of hydrogen peroxide in response to tumor necrosis factor, but only when the cells were adherent to surfaces coated with extracellular matrix proteins. The PMN did not respond when exposed to cytokines and matrix proteins in suspension, or when exposed to cytokines while adherent to surfaces coated with stearic acid. PMN from children with genetic deficiency of the CD11/CD18 integrins underwent a normal respiratory burst upon adherence to uncoated polystyrene, but not in response to tumor necrosis factor when tested on polystyrene that was coated with serum, fibronectin, vitronectin, fibrinogen, thrombospondin, or laminin. Anti-CD18 antibodies, alone of sixteen antibodies tested, induced a similar defect in PMN from normal donors, when the PMN were tested on surfaces coated with serum, fibrinogen, thrombospondin, or laminin; no defect was induced by the anti-CD18 monoclonal antibody IB4 in normal PMN tested on surfaces coated with fibronectin or vitronectin. Thus, for cytokines to induce a respiratory burst in PMN, the cells must be able to use CD11/CD18 integrins and must interact with matrix proteins in the solid phase. CD11/CD18, which is already known to serve as a receptor for fibrinogen, may also be a receptor for thrombospondin and laminin. Finally, receptor(s) exist on PMN for fibronectin and vitronectin which are not blocked by the anti-CD18 antibody IB4 but which are nonetheless CD11/CD18 dependent.

Failure of fenfluramine to affect basal and insulin-stimulated hexose transport in rat skeletal muscle

Fenfluramine is an effective appetite suppressant that mediates its action via serotoninergic neurons. We studied the effect of pure d- and l-fenfluramine on in vitro hexose transport in isolated rat soleus muscles and skeletal muscle cells in culture. We found no evidence to suggest that the fenfluramine enantiomers affect the basal transport activity. Furthermore, the drugs did not interfere with the ability of glucose to regulate its own transport. Muscle responsiveness to insulin was not altered by the enantiomers, nor did insulin unmask any effect of fenfluramine on muscle hexose transport. These conclusions are based on experiments performed with a wide concentration range of drug and insulin, from the therapeutic to suprapharmacological levels. We discuss our results in view of published data on the effects of fenfluramine on peripheral glucose metabolism.

Comparison of transforming growth factor-beta and a macrophage- deactivating polypeptide from tumor cells. Differences in antigenicity and mechanism of action

A factor in medium conditioned by mouse tumor cells was shown previously to suppress the capacity of mouse peritoneal macrophages to undergo a respiratory burst and to kill protozoal pathogens (macrophage deactivation factor, MDF). Recently, pure transforming growth factor-beta (TGF-beta) proved to be a potent macrophage deactivator as well. Two lines of evidence suggest that MDF is not identical with TGF-beta. First, rabbit anti-TGF-beta IgG neutralized the respiratory burst-suppressing activity of TGF-beta without affecting the bioactivity of MDF, even when the latter was treated with acid to activate potentially latent TGF-beta. Second, in contrast to MDF, which decreases the affinity of the NADPH oxidase for NADPH, permeabilized macrophages that had been deactivated with TGF-beta displayed the same Km and Vmax of the oxidase as activated macrophages. As with MDF, TGF-beta had no effect on two other potential control points over the secretion of respiratory burst products, namely, hydrogen peroxide catabolism or glucose uptake. Finally, neither MDF nor TGF-beta affected the extent or affinity of binding of phorbol diesters to macrophages, the activity or cofactor requirements for protein kinase C, or the ability of protein kinase C to translocate quantitatively from cytosol to membrane fractions in response to phorbol diesters. Thus, 1) MDF is not identical with TGF-beta, and 2) in contrast to the activation or deactivation of macrophages by numerous other agents, TGF-beta regulates macrophage respiratory burst capacity at a level other than the apparent affinity of the oxidase for its substrate.

Comparison of transforming growth factor-beta and a macrophage- deactivating polypeptide from tumor cells. Differences in antigenicity and mechanism of action

A factor in medium conditioned by mouse tumor cells was shown previously to suppress the capacity of mouse peritoneal macrophages to undergo a respiratory burst and to kill protozoal pathogens (macrophage deactivation factor, MDF). Recently, pure transforming growth factor-beta (TGF-beta) proved to be a potent macrophage deactivator as well. Two lines of evidence suggest that MDF is not identical with TGF-beta. First, rabbit anti-TGF-beta IgG neutralized the respiratory burst-suppressing activity of TGF-beta without affecting the bioactivity of MDF, even when the latter was treated with acid to activate potentially latent TGF-beta. Second, in contrast to MDF, which decreases the affinity of the NADPH oxidase for NADPH, permeabilized macrophages that had been deactivated with TGF-beta displayed the same Km and Vmax of the oxidase as activated macrophages. As with MDF, TGF-beta had no effect on two other potential control points over the secretion of respiratory burst products, namely, hydrogen peroxide catabolism or glucose uptake. Finally, neither MDF nor TGF-beta affected the extent or affinity of binding of phorbol diesters to macrophages, the activity or cofactor requirements for protein kinase C, or the ability of protein kinase C to translocate quantitatively from cytosol to membrane fractions in response to phorbol diesters. Thus, 1) MDF is not identical with TGF-beta, and 2) in contrast to the activation or deactivation of macrophages by numerous other agents, TGF-beta regulates macrophage respiratory burst capacity at a level other than the apparent affinity of the oxidase for its substrate.

Isolation of a complementary DNA clone encoding a precursor to human eosinophil major basic protein

A 14-kD protein was purified from human PMNs and its NH2-terminal sequence was determined. Comparison of a portion of the NH2-terminal sequence of this protein to the recently reported NH2-terminal sequence of eosinophil major basic protein (MBP) showed them to be identical. To aid further characterization of the structural and functional properties of this molecule, we isolated from an HL-60 cDNA library a single class of cDNA clones whose sequence matched exactly the NH2-terminal amino acid sequence of the 14-kD polypeptide. Northern analysis of HL-60 cells suggests that MBP is constitutively expressed in HL-60 cells and is highly transcribed from a single copy gene. The sequence of the full-length cDNA clones predicts that MBP is synthesized as a 23-kD precursor form (pro-MBP) which is subsequently cleaved to release the mature 14-kD MBP. The putative pro-MBP has a predicted pI of 6.0, but both the charged and the hydrophobic residues are asymmetrically distributed, creating a bipolar molecule. The NH2-terminal half has a predicted pI of 3.7 and is hydrophilic, while the COOH-terminal half (corresponding to mature MBP) has a predicted pI of 11.1 and is hydrophobic.

Identification of arginine as a precursor of endothelium-derived relaxing factor

Nitric oxide (NO) is a major endothelium-derived relaxing factor (EDRF) released in response to vasodilating amines, peptides, proteins, ionophores, and nucleotides. EDRF is an important regulator of smooth muscle tone and platelet aggregation and adhesion. Histamine and acetylcholine relax the intact norepinephrine-constricted guinea pig pulmonary artery by an EDRF-dependent mechanism in a medium free of amino acids. N omega-Monomethylarginine (N-MeArg; 0.25 mM) inhibited this relaxation by 64-73%. Inhibition by N-MeArg developed rapidly and was immediately and completely reversed by excess L-arginine but not by D-arginine or by citrulline. N-MeArg did not diminish relaxation induced by nitroprusside, an NO-generating agent, indicating that N-MeArg acts on endothelium rather than on smooth muscle. These observations strongly suggest that, in the intact guinea pig pulmonary artery, EDRF originates from enzymatic action on the guanido nitrogen(s) of an endogenous pool of arginine. This is strikingly similar to the origin of reactive nitrogen intermediates in activated macrophages.

Deactivation of macrophages by transforming growth factor-beta

Macrophage activation--enhanced capacity to kill, in a cell that otherwise mostly scavenges--is essential for host survival from infection and contributes to containment of tumours. Both microbes and tumour cells, therefore, may be under pressure to inhibit or reverse the activation of macrophages. This reasoning led to the demonstration of macrophage deactivating factors from both microbes and tumour cells. In some circumstances the host itself probably requires the ability to deactivate macrophages. Macrophages are essential to the healing of wounds and repair of tissues damaged by inflammation. Yet the cytotoxic products of the activated macrophages can damage endothelium, fibroblasts, smooth muscle and parenchymal cells (reviewed in ref. 6). Thus, after an inflammatory site has been sterilized, the impact of macrophage activation on the host might shift from benefit to detriment. These concepts led us to search for macrophage deactivating effects among polypeptide growth factors that regulate angiogenesis, fibrogenesis and other aspects of tissue repair. Among 11 such factors, two proteins that are 71% similar proved to be potent macrophage deactivators: these are transforming growth factor-beta 1 (TGF-beta 1) and TGF-beta 2.