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E Brummer

Publications and source records attributed to E Brummer.

At least 55 records · Page 3Linked to original sources
PubMed1995

Antifungal mechanisms of activated murine bronchoalveolar or peritoneal macrophages for Histoplasma capsulatum.

The first line of defence against natural infection by Histoplasma capsulatum (Hc) consists of bronchoalveolar macrophages (BAM) and an early inflammatory response in the lungs. Little is known about the interaction of BAM and Hc, consequently we studied murine BAM in vitro to assess their role in the pulmonary defence in histoplasmosis. A short-term 3-h assay was used to measure fungicidal activity of control BAM and interferon-gamma (IFN-gamma) plus lipopolysaccharide (LPS)-activated BAM. Fungistatic activity of BAM was determined with a 24-h assay. A method devised for measuring colony-forming units (CFU) of non-ingested non-adherent and adherent ingested yeast cells of Hc in BAM cocultures was used. Activated BAM killed Hc (reduced inoculum CFU by 25 +/- 12%; n = 4). The fungicidal activity of BAM was abrogated by 0.2 mM NG-monomethyl-L-arginine (NMMA) or catalase but not by superoxide dismutase. In fungistatic assays activated BAM inhibited multiplication of Hc by 61 +/- 4% (n = 3) compared with cocultures with control BAM. However, Hc multiplied 100% more in control BAM cocultures than in medium alone. Data indicated that this was due to advantages that Hc has in the intracellular environment. Only NMMA inhibited fungistatic activity of activated BAM. In experiments with peritoneal macrophages (PM), results similar to those with BAM were obtained. In conclusion, activated BAM and PM kill yeast cells of Hc by a mechanism dependent on hydrogen peroxide and products of the nitric oxide synthase (NOS) pathway, whereas fungistasis depends only on products of the NOS pathway.

Animals↗
PubMed1995

Different components in human serum inhibit multiplication of Cryptococcus neoformans and enhance fluconazole activity.

The inhibitory effect of human serum on the multiplication of Cryptococcus neoformans and the interaction with fluconazole were studied. Compared with cryptococcal multiplication in RPMI 1640 medium alone, 5% human serum in medium inhibited multiplication by 76% +/- 6% (n = 8). The inhibitory effect of human serum was donor independent, [corrected] heat stable (56 degrees C, 30 min), and not due to albumin or globulin. Bovine and murine sera were not inhibitory at that concentration. A fungistatic concentration of fluconazole (5.0 micrograms/ml) in medium plus 5% human serum resulted in 40% +/- 5% (n = 8) killing (reduction of inoculum CFU) in a 24-h assay. Bovine or murine sera did not have the enhancing effect, and this human serum activity was heat stable and donor independent. At 2.5 micrograms of fluconazole per ml, fungistasis by fluconazole plus human serum was significantly greater than with either alone. Higher serum concentrations [corrected] potentiated fluconazole more. At higher fluconazole concentrations (e.g., 20 micrograms/ml) fluconazole alone could kill, but serum potentiated this. A fluconazole-resistant isolate (MIC, 100 micrograms/ml) was not killed by fluconazole (5.0 micrograms/ml) in 5% human serum, but human serum potentiated the partial fluconazole inhibition. When human serum was dialyzed (molecular weight cutoff, 6,000 to 8,000) against phosphate-buffered saline, it lost the ability to synergize with fluconazole for killing Cryptococcus organisms but not the capacity to inhibit multiplication. Filtration of serum suggested the filtrate with a molecular weight of < 10,000 could interact synergistically with fluconazole for killing but could not inhibit cryptococcal multiplication. These findings indicate that human serum has two components, one (macromolecular) with a unique ability to inhibit C. neoformans and a low-molecular-weight component that enhances fluconazole anticryptococcal activity.

Animals↗
PubMed1994

Anticryptococcal activity of macrophages: role of mouse strain, C5, contact, phagocytosis, and L-arginine.

The antifungal activity of nonactivated resident murine peritoneal macrophages for Cryptococcus neoformans was studied. Macrophages from five of six mouse strains tested had significant (40 to 80%) fungistatic activity, depending on the inoculum size, in a 24-hr coculture system. Macrophages from two outbred (SW and ICR) and three inbred (BALB/c, C57Bl/6, and DBA/2J) strains were fungistatic. Only macrophages from outbred CD-1 mice lacked fungistatic activity. Heat-inactivated and C5-deficient sera did not support phagocytosis or fungistasis by resident BALB/c or DBA/2 macrophages. Fungistasis correlated with contact, complement, and phagocytosis. Macrophages were studied in a Lab-Tek chamber slide system where noningested cells were washed away. Fungistasis in this system was similar to that found with a microtest plate coculture method where a smaller inoculum was cultured continuously with macrophages. After ingestion of yeast cells, CD-1 macrophages could be activated for fungistasis (70%) with interferon-gamma plus lipopolysaccharide. Activated BALB/c macrophages had increased fungistasis but were not fungicidal. NG-Monomethyl-L-arginine (200 microM), which inhibited the fungistatic activity of activated CD-1 macrophages, did not inhibit inherent fungistatic activity of BALB/c macrophages. The fungistatic mechanism of BALB/c macrophages resembled that reported for resident human macrophages.

Animals↗
PubMed1994

Effect of macrophage colony-stimulating factor (M-CSF) on macrophage morphology, phagocytosis, and intracellular multiplication of Histoplasma capsulatum.

M-CSF induced dramatic morphological changes in resident peritoneal macrophages (R-PM) in a time and dose dependent manner. Macrophages increased 2-3-fold in size and developed a dendritic morphology. Compared to macrophages cultured in medium alone M-CSF-treated macrophages were less phagocytic (67 versus 82%) for serum opsonized yeast cells of Histoplasma capsulatum. However, in M-CSF macrophages the intracellular multiplication of ingested yeast cells were significantly inhibited compared to growth in control macrophages. The fungistatic activity of M-CSF macrophages persisted for at least 48 h after infection.

Animals↗
PubMed1994

Macrophage colony-stimulating factor induction of enhanced macrophage anticryptococcal activity: synergy with fluconazole for killing.

Enhancement of anticryptococcal activity in macrophages by macrophage colony-stimulating factor (M-CSF) and possible synergy between macrophages and fluconazole for killing of Cryptococcus neoformans were tested. M-CSF (48 h)-treated macrophages underwent dramatic morphologic changes and inhibited cryptococcal multiplication by 96% +/- 4%, which was greater (P < .001) than that of macrophages cultured in medium alone. M-CSF (5000 units/mL) induced optimal anticryptococcal activity but did not increase percentage of phagocytosis. NG-mono-methyl-L-arginine did not affect enhanced fungistatic activity. For a very fluconazole-sensitive isolate, fungistatic macrophages synergized with fungistatic doses of fluconazole for killing; for a less sensitive isolate, synergy was significant only when macrophages were activated with M-CSF or interferon-gamma plus lipopolysaccharide; for a fluconazole-resistant isolate, macrophages collaborated with fluconazole for additive fungistasis but not killing, and M-CSF-treated macrophages were significantly more fungistatic with fluconazole than were nonactivated macrophages.

Animals↗
PubMed1994

Support of Paracoccidioides brasiliensis multiplication by human monocytes or macrophages: inhibition by activated phagocytes.

The interaction of human monocytes or monocyte-derived macrophages and yeast-form Paracoccidioides brasiliensis was studied in vitro. Yeast cells were readily ingested by adherent monocytes or macrophages. Multiplication of P. brasiliensis, measured by growth as colony forming units (cfu) on a supplemented medium with good plating efficiency, was greater in monocyte co-cultures compared to the number of cfu obtained from complete tissue-culture medium (CTCM). Multiplication increased with time in macrophage co-cultures, e.g., from two-six-fold in 24 h to nine-fold in 72 h. Microscopic observations indicated that ingested yeast cells multiplied inside macrophages. When monocytes were treated with supernate cytokines (CK) from concanavalin-A-stimulated mononuclear cells, then co-cultured with P. brasiliensis, multiplication was significantly inhibited compared with control monocyte co-cultures. Treatment of macrophages--derived from monocytes by culture in vitro for 3 days--for a further 3 days with CK resulted in maximal inhibition of multiplication over the subsequent 72 h. Similarly, when monocyte-derived macrophages (after culture for 7 days) were treated for 3 days with recombinant human gamma-interferon (IFN; 300 U/ml) or CK they restricted multiplication of P. brasiliensis by 65% and 95%, respectively, compared with control macrophages. Antibody to IFN abrogated the effect of IFN or CK treatment. These findings show that ingested P. brasiliensis can multiply in human monocytes or macrophages and that this multiplication can be restricted by activated monocytes or macrophages.

Adult↗
PubMed1994

Cytokine treatment of central nervous system infection: efficacy of interleukin-12 alone and synergy with conventional antifungal therapy in experimental cryptococcosis.

Cell-mediated immune responses appear to be critical in the outcome of cryptococcosis. Interleukin-12 (IL-12) was studied for its potential use as a therapeutic agent because of its stimulation of natural killer cells and gamma interferon production by stimulated T cells and natural killer cells. Gamma interferon-activated macrophages are important in host resistance against cryptococcosis. In two separate studies, male BALB/c mice were infected intravenously with Cryptococcus neoformans. In the first study, mice received either no treatment, 5.0 mg of fluconazole alone per kg of body weight per day (by gavage twice daily), or IL-12 subcutaneously at 0.01, 0.1, or 1.0 microgram/day once daily (low-dose study) alone or in combination with 5.0 mg of fluconazole per kg/day. In a second study (high dose), the dosages of IL-12 used were 1.0, 2.5, or 5.0 micrograms/day. Therapy was given for 10 consecutive days, and the number of CFU of C. neoformans remaining in various organs was quantitated 1 or 2 days after administration of the last dose. In the low-dose study, IL-12 at 0.1 or 1.0 microgram reduced the level of brain infection by approximately 10-fold (P < 0.05) and IL-12 at 1.0 or 0.1 microgram/day enhanced the efficacy of fluconazole. In liver, both the efficacy of IL-12 alone (0.01 or 0.1 microgram; P < 0.05) and enhancement of the efficacy of fluconazole (P < 0.05) were seen. No efficacy of IL-12 was seen in spleens or lungs, although spleen weights increased fourfold in mice given 1.0 microgram of IL-12 per day. In the high-dose study, all IL-12 doses alone again reduced the levels of brain infection (5- to 8-fold; P < 0.05) when the two were given in combination. No overt toxicities were observed at any dose, and overall, 1.0 microgram of IL-12 per day was found to be the optimal dosage for reducing infection in the brain. To our knowledge, this is the first demonstration of the efficacy of cytokine therapy in systemic and particularly brain infections with C. neoformans. The stimulation of cell-mediated immunity represents a new approach to therapy and can enhance suboptimal antimicrobial chemotherapy. IL-12 should be considered for further study and for clinical trials. These studies suggest that other opportunistic central nervous system pathogens should also be investigated.

Animals↗
PubMed1994

Effect of macrophage colony-stimulating factor on anticryptococcal activity of bronchoalveolar macrophages: synergy with fluconazole for killing.

The anticryptococcal activity of murine bronchoalveolar macrophages (BAM) and their synergy with fluconazole (FCZ) was studied. BAM cultured with tissue culture medium for 48 to 72 h were fungicidal (24 to 39%) in a 3-h killing assay. However, net killing of Cryptococcus neoformans did not continue when culture time was extended to 24 h, although BAM were fungistatic (88 to 98%). Treatment with macrophage colony-stimulating factor (M-CSF; 5,000 U/ml, 48 h) did not significantly increase BAM killing of a low challenge dose in 3-h assays compared with control BAM. However, M-CSF-treated BAM were significantly more fungistatic against higher challenge doses in the 3-h assays. FCZ was not fungicidal at 5 micrograms/ml but was highly fungistatic (98 and 99% at 24 and 48 h, respectively). M-CSF-treated BAM acted synergistically with FCZ (2.5 micrograms/ml) for significantly greater killing than control BAM, 55% versus 20% and 96% versus 45% at 24 h and 48 h, respectively. Killing by M-CSF BAM and FCZ (5.0 micrograms/ml) was significantly (P < 0.01) greater than that by control BAM and FCZ at 48 h. These findings indicate an important collaborative role for BAM and FCZ in killing C. neoformans, and this is enhanced by M-CSF.

Animals↗
PubMed1994

Effect of in vivo macrophage colony-stimulating factor on fungistasis of bronchoalveolar and peritoneal macrophages against Cryptococcus neoformans.

Macrophage colony-stimulating factor (M-CSF) given subcutaneously at a dose of 2.5 mg/kg of body weight (4.75 x 10(6) U/kg) to CD-1 male mice 8 to 12 weeks old was found to enhance significantly the fungistasis of bronchoalveolar macrophages (BAM) against Cryptococcus neoformans. When M-CSF was given 1, 3, 7, 9, or 13 days before an ex vivo challenge with C. neoformans, fungistasis was increased (P ranged from < 0.05 to < 0.001) compared with that induced by control BAM. A maximum effect was seen by days 1 and 3 after administration of M-CSF. Twenty-one days after M-CSF, BAM did not produce significantly enhanced fungistasis. M-CSF also significantly enhances the fungistatic effect of peritoneal macrophages (PM) if given 1, 3, and 7 days prior to testing against C. neoformans in comparison with control PM (P ranged from < 0.05 to < 0.001). PM did not produce enhanced fungistasis 9 or 13 days after administration of M-CSF. These studies demonstrating in vivo enhancement of anticryptococcal activity of macrophages with M-CSF provide a rationale for in vivo use of M-CSF to enhance resistance to infection with C. neoformans.

Animals↗
PubMed1994

Inhibitory effect of deferoxamine or macrophage activation on transformation of Paracoccidioides brasiliensis conidia ingested by macrophages: reversal by holotransferrin.

Conidia of P. brasiliensis ingested by murine macrophages at 37 degrees C showed enhanced transformation to yeast cells and further intracellular growth compared with conidia in culture medium alone. Treatment of macrophages with the iron chelator deferoxamine inhibited the intracellular conidium-to-yeast transformation. Cytokine-activated macrophages could also exert this inhibitory effect. Holotransferrin reversed the inhibitory effect of either deferoxamine or activated macrophages on intracellular conidium-to-yeast transformation. These results indicate that iron restriction is one of the mechanisms by which activated macrophages control the intracellular transformation of ingested conidia and growth of yeast cells.

Animals↗
PubMed1993

IL-4, IgE, and interferon-gamma production in pulmonary blastomycosis: comparison in mice untreated, immunized, or treated with an antifungal (SCH 39304).

The purpose of this study was to determine if there is a correlation between production of certain lymphokines in progressive blastomycosis in untreated mice, resistance to infection in immunized mice, and cure in antifungal triazole (SCH 39304)-treated mice. Infection was measured by colony-forming units of Blastomyces dermatitidis in lungs. Serum level of IgE was used as a marker for in vivo IL-4 activity. Serum IgE levels rose in untreated mice from 6 micrograms/ml at 3 weeks to 24 micrograms/ml by the fourth week as their infection progressed. This corresponded to a peak in vitro production of IL-4 (147 pg/ml) by antigen-stimulated spleen cells at Week 4. By contrast, there was an inverse relationship between serum IgE- and antigen-stimulated production of IFN-gamma in vitro, e.g., 80 U/ml at the third week and 4 U/ml at Week 4. In mice undergoing cure with SCH 39304, serum IgE decreased from 12 micrograms/ml at the third week to 2 micrograms/ml at Week 4. This correlated with a drop in IL-4 and an increase in IFN-gamma production in in vitro assays. As cure proceeded over the next 4 weeks, IgE and IFN-gamma measurements were near background levels. In immunized mice a low-grade chronic blastomycosis emerged after 3 weeks of infection. Chronic infection was associated with inverse cycles of elevated IgE in serum and IFN-gamma production as assayed in vitro. IL-4 production cycled directly with increased IgE levels in serum. Although spleen cells from untreated mice produced IFN-gamma and IL-4 when stimulated with antigen, they did not mount significant proliferative responses. By contrast, spleen cells and lymph node cells from immunized and SCH 39304-treated mice made good proliferative responses to antigen and this correlated with resistance and clearing of the infection, respectively. These data indicate that in pulmonary blastomycosis, serum IgE levels correlate directly with IL-4 and inversely with IFN-gamma production. Clearing of the infection by the antifungal agent SCH 39304 reduces lymphokine production to background levels but sensitizes lymphocytes for proliferative responses to antigen.

Animals↗
PubMed1993

Effect of anti-IL-4, interferon-gamma and an antifungal triazole (SCH 42427) in paracoccidioidomycosis: correlation of IgE levels with outcome.

Paracoccidioidomycosis is characterized by depressed cellular but enhanced humoral immune responses, which suggests a Th2 type of response to infection. We investigated possible therapeutic roles for anti-IL-4, interferon-gamma (IFN-gamma) and/or SCH 42427 (SCH), a new triazole antifungal agent, and their effect on serum IgE levels in a murine model of chronic Paracoccidioides brasiliensis infection. BALB/c mice infected by the pulmonary route were studied with three programmes. The subacute model and one acute model experiment investigated cytokine secretion by lymph node cells (LNC), and in a second acute experiment mice were given anti-IL-4, IFN-gamma or nothing 24 h post infection, then killed at 4 weeks. In the chronic model, mice began treatment at 4 weeks post infection, receiving either SCH, IFN-gamma alone, SCH+IFN-gamma, or no treatment for 8 weeks. At 2-week intervals lung and spleen burdens of infection and serum polyclonal IgE levels were determined. In the subacute model (non-progressive infection), initially there was dual production of IL-4 and IFN-gamma by antigen-stimulated LNC. In the acute progressive infection model IL-4, but not IFN-gamma, was secreted. Anti-IL-4 treatment of the acute phase resulted in enhanced host resistance to infection, which correlated with decreased serum IgE. The chronic model, in which the in vivo efficacy of SCH against P. brasiliensis was shown, suggests possible synergy between immunomodulation and antimicrobial chemotherapy (IFN-gamma and SCH). Decreased organ burdens of infection in the chronic model after treatment with SCH, SCH plus IFN-gamma, or anti-IL-4 correlated with decreased serum IgE. These promising novel approaches to treatment of systemic fungal infections suggest a Th2 type of response to P. brasiliensis infection, which can be reversed with successful therapy.

Animals↗
PubMed1993

Paracoccidioidomycosis: an update.

This review summarizes knowledge on various aspects of paracoccidioidomycosis. Mycelial propagules, chlamydospores, and arthroconidia exhibit thermal dimorphism; arthroconidia are infectious in animals and, by electron microscopy, appear well provided for survival. The mycelial-to-yeast-phase transformation requires a strict control of glucan synthesis probably mediated by membrane enzymes. Hormonal influences on the transformation of the fungus (mycelium or conidium to yeast phase) have been demonstrated. Estrogen-binding proteins have been detected in the fungal cytosol, and during the transformation novel proteins are produced as a result of estradiol incorporation. Clinical forms have been better defined on the basis of better experimental models. Emphasis has been placed on the lungs as the portal of entry and on the existence of silent pulmonary infections. A specific Paracoccidioides brasiliensis antigen, the 43-kDa glycoprotein (Gp43), has been identified, characterized, and cloned. This has led to improved reproducibility and specificity of serologic tests. The depression of cell-mediated immune responses has been associated with severe disease in humans and in the experimental host. T-cell subsets in patients' tissues were characterized by means of monoclonal antibodies, and a reduced CD4/CD8 ratio was demonstrated. This has been related to alterations in lymphokine and tumor necrosis factor production, production of antigen-antibody complexes, etc. Amphotericin B has provided effective therapy. Azole derivatives have also improved prognosis and facilitated therapy. Itraconazole is presently the drug of choice, yet incapacitating sequelae (mainly pulmonary fibrosis) still constitute major problems.

Adult↗
PubMed1992

A basis for resistance of Blastomyces dermatitidis killing by human neutrophils: inefficient generation of myeloperoxidase system products.

The mechanism by which the yeast form of Blastomyces dermatitidis resists killing by human peripheral blood polymorphonuclear neutrophils (PMN) was investigated. The metabolic products of the oxidative burst generated during the interaction of PMN and B. dermatitidis or Candida albicans were detected by lucigenin- or luminol-enhanced chemiluminescence (CL). Interaction of PMN and C. albicans resulted in luminol-enhanced CL 100-fold greater than that generated by PMN and B. dermatitidis. This correlated with killing of C. albicans and resistance of B. dermatitidis. Since B. dermatitidis and PMN interactions resulted in significant lucigenin-enhanced CL, deficient luminol CL was not due to a lack of products from the NADPH oxidase system. Killed B. dermatitidis cells at 37 degrees C were more efficient than live cells in stimulating PMN for luminol-enhanced CL; however, only fragmented B. dermatitidis cells elicited luminol-enhanced CL equivalent to that of C. albicans. Since lysates of PMN were active in a cell-free hydrogen peroxide-peroxidase-halide system, resistance of B. dermatitidis to PMN was not due to a defect in PMN peroxidase. Taken together, these findings indicate that resistance of B. dermatitidis to killing by PMN results from inefficient generation of products from the peroxidase-dependent PMN microbicidal system.

Acridines↗
PubMed1992

Synergy of itraconazole with macrophages in killing Blastomyces dermatitidis.

We examined in vitro interaction between the azole antifungal agents itraconazole and ketoconazole and macrophages and their activities against Blastomyces dermatitidis. Fungistatic and fungicidal concentrations for B. dermatitidis in vitro were assessed in a microculture system in which fungistasis was measured as inhibition of multiplication and fungicidal activity was measured as reduction of inoculum CFU. Resident peritoneal murine macrophages, which surround but do not phagocytize the fungus, were not fungicidal for B. dermatitidis isolates but were fungistatic for some isolates studied. Synergy was demonstrated when fungistatic concentrations (e.g., 0.01 micrograms/ml) of itraconazole, which limited growth 55% compared with that of controls, were cocultured with macrophages; this resulted in fungicidal activity (85% killing) against B. dermatitidis (ATCC 26199) in 72-h assays. This synergy could occur even if itraconazole was added after the macrophages had surrounded the fungus. Ketoconazole at fungistatic concentrations did not act synergistically with macrophages to kill B. dermatitidis. Lymph node lymphocytes could not substitute for macrophages in synergy with itraconazole to kill B. dermatitidis. When B. dermatitidis was separated by a filter from macrophages in Transwell cultures, fungicidal synergy with itraconazole was less efficient. Pretreatment of B. dermatitidis with itraconazole for 24 h did not render the fungus susceptible to killing by macrophages in the absence of itraconazole, whereas pretreatment of nonfungistatic macrophages with itraconazole rendered them fungistatic in a dose-dependent manner. Three other isolates were killed by otherwise fungistatic concentrations of itraconazole when the isolates were cocultured with macrophages. These findings indicate that one basis for the efficacy of itraconazole versus ketoconazole in treating blastomycosis could be synergy of a fungistatic concentration of itraconazole with macrophages in killing of B. dermatitidis.

Animals↗
PubMed1992

Fate of conidia of Paracoccidioides brasiliensis after ingestion by resident macrophages or cytokine-treated macrophages.

Conidia ingested by resident macrophages had an enhanced percentage of transformation to yeast cells compared with those in culture medium without macrophages. The yeast cells subsequently grew intracellularly by budding. Macrophages treated with cytokines from antigen-stimulated spleen cells from immunized mice significantly inhibited transformation of ingested conidia.

Animals↗