ABSTRACT
Prostaglandins (PGs) and leukotrienes (LTs) are produced in Mycobacterium tuberculosis (Mtb)-infected lungs and have immune suppressive and protective effects, respectively. Considering that both of these mediators are produced during mycobacterial infection, we investigated the specific and relative biological importance of each in regulating host response in experimental tuberculosis. Administration of celecoxib, which was found to reduce lung levels of PGE(2) and increase LTB(4), enhanced the 60-day survival of Mtb-infected mice in 14%. However administration of MK-886, which reduced levels of LTB(4) but did not enhance PGE(2), reduced 60-day survival from 86% to 43% in Mtb-infected mice, and increased lung bacterial burden. MK-886 plus celecoxib reduced survival to a lesser extent than MK-886 alone. MK-886- and MK-886 plus celecoxib-treated animals exhibited reduced levels of the protective interleukin-12 and gamma-interferon. Our findings indicate that in this model, the protective effect of LTs dominates over the suppressive effect of PGs.
Subject(s)
Adjuvants, Immunologic/pharmacology , Immunosuppressive Agents/pharmacology , Leukotrienes/pharmacology , Lung/drug effects , Mycobacterium tuberculosis/drug effects , Prostaglandins/pharmacology , Animals , Bronchoalveolar Lavage Fluid/immunology , Bronchoalveolar Lavage Fluid/microbiology , Cytokines/immunology , Cytokines/metabolism , Indoles/pharmacology , Leukotrienes/immunology , Lipoxygenase Inhibitors/pharmacology , Lung/immunology , Lung/microbiology , Male , Mice , Mice, Inbred BALB C , Mycobacterium tuberculosis/growth & development , Mycobacterium tuberculosis/immunology , Nitric Oxide/immunology , Nitric Oxide/metabolism , Prostaglandins/immunology , Tuberculosis, Pulmonary/immunology , Tuberculosis, Pulmonary/pathology , Tuberculosis, Pulmonary/prevention & controlABSTRACT
Leukotrienes are reported to be potent proinflammatory mediators that play a role in the development of several inflammatory diseases such as asthma, rheumatoid arthritis and periodontal disease. Leukotrienes have also been associated with protection against infectious diseases. However, the role of leukotrienes in Mycobacterium tuberculosis infection is not understood. To answer this question, we studied the role of leukotrienes in the protective immune response conferred by prime-boost heterologous immunization against tuberculosis. We immunized BALB/c mice (4-11/group) with subcutaneous BCG vaccine (1 x 10(5) M. bovis BCG) (prime) followed by intramuscular DNA-HSP65 vaccine (100 µg) (boost). During the 30 days following the challenge, the animals were treated by gavage daily with MK-886 (5 mg·kg-1·day-1) to inhibit leukotriene synthesis. We showed that MK-886-treated mice were more susceptible to M. tuberculosis infection by counting the number of M. tuberculosis colony-forming units in lungs. The histopathological analysis showed an impaired influx of leukocytes to the lungs of MK-886-treated mice after infection, confirming the involvement of leukotrienes in the protective immune response against experimental tuberculosis. However, prime-boost-immunized mice treated with MK-886 remained protected after challenge with M. tuberculosis, suggesting that leukotrienes are not required for the protective effect elicited by immunization. Protection against M. tuberculosis challenge achieved by prime-boost immunization in the absence of leukotrienes was accompanied by an increase in IL-17 production in the lungs of these animals, as measured by ELISA. Therefore, these data suggest that the production of IL-17 in MK-886-treated, immunized mice could contribute to the generation of a protective immune response after infection with M. tuberculosis.
Subject(s)
Animals , Female , Mice , Bacterial Proteins/immunology , /immunology , Leukocytes/immunology , Leukotrienes/biosynthesis , Tuberculosis, Pulmonary/prevention & control , Vaccines, DNA/immunology , BCG Vaccine/administration & dosage , BCG Vaccine/immunology , Bacterial Proteins/administration & dosage , Cell Movement , /administration & dosage , Cytokines/biosynthesis , Immunization, Secondary , Indoles/pharmacology , Leukotriene Antagonists/pharmacology , Leukotrienes/agonists , Lung/immunology , Lung/microbiology , Lung/pathology , Mice, Inbred BALB C , Tuberculosis, Pulmonary/immunology , Tuberculosis, Pulmonary/pathology , Vaccines, DNA/administration & dosageABSTRACT
Leukotrienes are reported to be potent proinflammatory mediators that play a role in the development of several inflammatory diseases such as asthma, rheumatoid arthritis and periodontal disease. Leukotrienes have also been associated with protection against infectious diseases. However, the role of leukotrienes in Mycobacterium tuberculosis infection is not understood. To answer this question, we studied the role of leukotrienes in the protective immune response conferred by prime-boost heterologous immunization against tuberculosis. We immunized BALB/c mice (4-11/group) with subcutaneous BCG vaccine (1 x 10(5) M. bovis BCG) (prime) followed by intramuscular DNA-HSP65 vaccine (100 microg) (boost). During the 30 days following the challenge, the animals were treated by gavage daily with MK-886 (5 mg x kg(-1) x day(-1)) to inhibit leukotriene synthesis. We showed that MK-886-treated mice were more susceptible to M. tuberculosis infection by counting the number of M. tuberculosis colony-forming units in lungs. The histopathological analysis showed an impaired influx of leukocytes to the lungs of MK-886-treated mice after infection, confirming the involvement of leukotrienes in the protective immune response against experimental tuberculosis. However, prime-boost-immunized mice treated with MK-886 remained protected after challenge with M. tuberculosis, suggesting that leukotrienes are not required for the protective effect elicited by immunization. Protection against M. tuberculosis challenge achieved by prime-boost immunization in the absence of leukotrienes was accompanied by an increase in IL-17 production in the lungs of these animals, as measured by ELISA. Therefore, these data suggest that the production of IL-17 in MK-886-treated, immunized mice could contribute to the generation of a protective immune response after infection with M. tuberculosis.
Subject(s)
Bacterial Proteins/immunology , Chaperonin 60/immunology , Leukocytes/immunology , Leukotrienes/biosynthesis , Tuberculosis, Pulmonary/prevention & control , Vaccines, DNA/immunology , Animals , BCG Vaccine/administration & dosage , BCG Vaccine/immunology , Bacterial Proteins/administration & dosage , Cell Movement , Chaperonin 60/administration & dosage , Cytokines/biosynthesis , Female , Immunization, Secondary , Indoles/pharmacology , Leukotriene Antagonists/pharmacology , Leukotrienes/agonists , Lung/immunology , Lung/microbiology , Lung/pathology , Mice , Mice, Inbred BALB C , Tuberculosis, Pulmonary/immunology , Tuberculosis, Pulmonary/pathology , Vaccines, DNA/administration & dosageABSTRACT
AIM: To evaluate in vitro the effect of calcium hydroxide [Ca(OH)(2)] and Er:YAG laser on bacterial endotoxin [also known as lipopolysaccharide (LPS)] as determined by nitric oxide (NO) detection in J774 murine macrophage cell line culture. METHODOLOGY: Samples of LPS solution (50 microg mL(-1)), Ca(OH)(2) suspension (25 mg mL(-1)) and LPS suspension with Ca(OH)(2) were prepared. The studied groups were: I - LPS (control); II - LPS + Ca(OH)(2); III - LPS + Er:YAG laser (15 Hz 140 mJ); IV - LPS + Er:YAG laser (15 Hz 200 mJ); V - LPS + Er:YAG laser (15 Hz 250 mJ), VI - Pyrogen-free water; VII - Ca(OH)(2). Murine macrophage J774 cells were plated and 10 microL of the samples were added to each well. The supernatants were collected for NO detection by the Griess reaction. Data were analysed statistically by one-way anova and Tukey's test at 5% significance level. RESULTS: The mean and SE (in micromol L(-1)) values of NO release were: I - 10.48 +/- 0.58, II - 6.41 +/- 0.90, III - 10.2 +/- 0.60, IV - 8.35 +/- 0.40, V - 10.40 +/- 0.53, VI - 3.75 +/- 0.70, VII - 6.44 +/- 0.60; and the values for the same experiment repeated after 1 week were: I - 21.20 +/- 1.50, II - 9.10 +/- 0.60, III - 19.50 +/- 1.00, IV - 18.50 +/- 0.60, V - 21.30 +/- 0.90, VI - 2.00+/- 0.20, VII - 6.80 +/- 1.70. There was no significant difference (P > 0.05) between the control and the laser-treated groups (III, IV and V), or comparing groups II, VI and VII to each other (P > 0.05). Group I had significantly higher NO release than group II (P < 0.05). Groups II and VI had similar NO release (P > 0.05). CONCLUSIONS: Calcium hydroxide inactivated the bacterial endotoxin (LPS) whereas none of the Er:YAG laser parameter settings had the same effectiveness.
Subject(s)
Calcium Hydroxide/pharmacology , Lasers, Solid-State , Lipopolysaccharides/antagonists & inhibitors , Macrophages/metabolism , Nitric Oxide/biosynthesis , Root Canal Irrigants/pharmacology , Animals , Cell Line , Escherichia coli/chemistry , Macrophages/drug effects , Mice , Nitric Oxide/analysisABSTRACT
OBJECTIVE: Suramin is a polysulphonated napthylurea antiprotozoal and anthelminitic drug, which also presents inhibitory activity against a broad range of enzymes. Here we evaluate the effect of suramin on the hydrolytic and biological activities of secreted human group IIA phospholipase A(2) (hsPLA(2)GIIA). MATERIALS AND METHODS: The hsPLA(2)GIIA was expressed in E. coli, and refolded from inclusion bodies. The hydrolytic activity of the recombinant enzyme was measured using mixed dioleoylphosphatidylcholine/dioleoylphosphatidylglycerol (DOPC/DOPG) liposomes. The activation of macrophage cell line RAW 264.7 by hsPLA(2) GIIA was monitored by NO release, and bactericidal activity against Micrococcus luteus was evaluated by colony counting and by flow cytometry using the fluorescent probe Sytox Green. RESULTS: The hydrolytic activity of the hsPLA(2) GIIA was inhibited by a concentration of 100 nM suramin and the activation of macrophages by hsPLA(2) GIIA was abolished at protein/suramin molar ratios where the hydrolytic activity of the enzyme was inhibited. In contrast, both the bactericidal activity of hsPLA(2) GIIA against Micrococcus luteus and permeabilization of the bacterial inner membrane were unaffected by suramin concentrations up to 50 microM. CONCLUSIONS: These results demonstrate that suramin selectively inhibits the activity of the hsPLA(2) GIIA against macrophages, whilst leaving the anti-bacterial function unchanged.
Subject(s)
Antinematodal Agents/pharmacology , Group II Phospholipases A2/metabolism , Macrophage Activation/drug effects , Suramin/pharmacology , Animals , Antinematodal Agents/chemistry , Cell Line , Group II Phospholipases A2/chemistry , Group II Phospholipases A2/genetics , Humans , Inclusion Bodies/enzymology , Macrophage Activation/physiology , Macrophages/cytology , Macrophages/physiology , Microbial Sensitivity Tests , Molecular Structure , Protein Conformation , Recombinant Proteins/chemistry , Recombinant Proteins/genetics , Recombinant Proteins/metabolism , Suramin/chemistryABSTRACT
Experimental toxocariasis was used as a model of eosinophil migration. Mice inoculated with 200 Toxocara canis eggs were treated with the leukotriene inhibitor MK886 (1 mg/kg/day). Eosinophils were counted in peripheral blood (PB), peritoneal cavity (PC) and bronchoalveolar lavage fluid (BALF) samples on post-infection days 3, 6, 12, 18, 24 and 36. Eosinophil expression of Mac-1 and VLA-4 was analysed in PB and PC samples. We found that T. canis infection induced systemic eosinophilia from post-infection day 3, peaking on days 6, 12 and 24 in PB, PC and BALF samples respectively. Eosinophilia was more pronounced in PB and PC samples than in BALF samples, and MK886 downregulated eosinophilia to varying degrees in the different sample types. In PB and PC samples, T. canis infection caused early upregulation of Mac-1 with late changes in the VLA-4 profile, whereas MK886 had opposite effects. The distinct time-dependent eosinophilia peaks and differential involvement of leukotrienes in integrin expression demonstrate that, despite the systemic eosinophilia triggered by T. canis infection, inflammatory responses vary by compartment.
Subject(s)
Eosinophilia/drug therapy , Eosinophils/drug effects , Indoles/therapeutic use , Lipoxygenase Inhibitors/therapeutic use , Toxocariasis/drug therapy , Animals , Bronchoalveolar Lavage Fluid/cytology , Bronchoalveolar Lavage Fluid/immunology , Cell Movement/drug effects , Cell Movement/immunology , Eosinophilia/immunology , Eosinophils/immunology , Female , Flow Cytometry , Integrin alpha4beta1/biosynthesis , Integrin alpha4beta1/drug effects , Macrophage-1 Antigen/biosynthesis , Macrophage-1 Antigen/drug effects , Mice , Mice, Inbred BALB C , Phenotype , Toxocariasis/immunologyABSTRACT
OBJECTIVE: This study examines the effect of ultrasonically nebulized distilled water inhalation on the systemic histamine hyperreactivity of Toxocara canis-infected mice. METHODS: Uninfected and T. canis-infected mice received an intravenous sublethal dose of histamine and lethality rates were documented. At 24 days post infection, infected mice received ultrasonically nebulized distilled water inhalation for 1 h. Twenty-four hours later histamine levels were determined in bronchoalveolar lavage fluid as well as histamine lethality and toluidine blue-stained mast cell number in the lung. RESULTS: T. canis-infected mice showed increased lethality after exposure to histamine in comparison to uninfected mice. Ultrasonically nebulized distilled water inhalation prevented histamine-induced lethality and reduced toluidine blue-stained mast cell numbers in the lung. CONCLUSIONS: The correlation between decreases in stained mast cells in the lung after ultrasonically nebulized distilled water inhalation and inhibition of histamine-induced lethality in these animals suggests participation of mast cells in the phenomenon and could be helpful in understanding the mechanisms of hyperreactivity during helminth parasite infections.
Subject(s)
Histamine/administration & dosage , Histamine/pharmacology , Hypersensitivity/prevention & control , Nebulizers and Vaporizers , Toxocara canis/physiology , Toxocariasis/complications , Water/administration & dosage , Anaphylaxis/chemically induced , Anaphylaxis/prevention & control , Animals , Female , Hypersensitivity/complications , Kinetics , Lung/drug effects , Lung/parasitology , Lung/pathology , Mast Cells/cytology , Mast Cells/drug effects , Mice , Mice, Inbred BALB C , Serotonin/pharmacology , Toxocariasis/parasitology , Ultrasonics , Water/chemistryABSTRACT
OBJECTIVE: In the present study, we evaluated the levels of MIP-1alpha and eotaxin and in vivo migration in the peritoneal cavity model, in mice inoculated with live yeast forms of Histoplasma capsulatum or the beta-glucan cell wall component of this fungus, and the influence of a leukotriene biosynthesis inhibitor, MK886, on the release of these chemokines in relation to cell recruitment. MATERIALS: Female outbred Swiss mice (N = 4-5 per group, 3-4 wk, were used. Mice were injected i.p. with 1 ml of the 6 x 10(5) live yeast form of the fungus or with 10 microg of beta-glucan from the cell wall fraction, and treated daily with MK886 (1 mg kg(-1), p.o.) or vehicle. RESULTS: The fungus induced rapid generation of high levels of MIP-1alpha, which remained elevated from 4-48 h whereas very little eotaxin was detected at any time point (Fig. 1A and B). In contrast, the beta-glucan induced a little MIP-1alpha but considerably higher concentrations of eotaxin within the first four hours; however, the level of neither chemokine was sustained (Fig. 2A and B). Treatment of animals with MK886 was effective in reducing the numbers of neutrophils, eosinophils and, to a lesser degree, mononuclear cells accumulating in the peritoneal cavity in response to both the live fungus (Fig. 1C-E) and the cell wall beta-glucan (Fig. 2C-E). CONCLUSIONS: The results suggest that chemokines and leukotrienes may play key roles in the inflammatory cell influx to H. capsulatum infection or to the inoculation of the beta-glucan cell wall component of this fungus
Subject(s)
Chemokines, CC/metabolism , Histoplasma/physiology , Histoplasmosis/metabolism , Macrophage Inflammatory Proteins/metabolism , beta-Glucans/administration & dosage , beta-Glucans/pharmacology , Animals , Cell Wall/chemistry , Chemokine CCL11 , Chemokine CCL3 , Chemokine CCL4 , Chemokines/blood , Female , Histoplasmosis/immunology , Inflammation/immunology , Inflammation/microbiology , Inflammation/pathology , Leukocytes/drug effects , Leukotrienes/biosynthesis , Leukotrienes/metabolism , Mice , Time FactorsABSTRACT
An alkali-insoluble fraction 1 (F1), which contains mainly ss-glucan isolated from the cell wall of Histoplasma capsulatum, induces eosinophil recruitment into the peritoneal cavity of mice. The present study was carried out to determine the participation of interleukin-5 (IL-5) in this process. Inbred C57BL/6 male mice weighing 15-20 g were treated ip with 100 microg of anti-IL-5 monoclonal antibody (TRFK-5, N=7) or an isotype-matched antibody (N=7), followed by 300 microg F1 in 1 ml PBS ip 24 h later. Controls (N=5) received only 1 ml PBS. Two days later, cells from the peritoneal cavity were harvested by injection of 3 ml PBS and total cell counts were determined using diluting fluid in a Neubauer chamber. Differential counts were performed using Rosenfeld-stained cytospin preparations. The F1 injection induced significant (P<0.01) leukocyte recruitment into the peritoneal cavity (8.4 x 10(6) cells/ml) when compared with PBS alone (5.5 x 10(6) cells/ml). Moreover, F1 selectively (P<0.01) induced eosinophil recruitment (1 x 10(6) cells/ml) when compared to the control group (0.07 x 10(6) cells/ml). Treatment with TRFK-5 significantly (P<0.01) inhibited eosinophil recruitment (0.18 x 10(6) cells/ml) by F1 without affecting recruitment of mononuclear cells or neutrophils. We conclude that the F1 fraction of the cell wall of H. capsulatum induces peritoneal eosinophilia by an IL-5-dependent mechanism. Depletion of this cytokine does not have effect on the recruitment of other cell types induced by F1.
Subject(s)
Eosinophils/drug effects , Glucans/pharmacology , Histoplasma/chemistry , Interleukin-5/physiology , Peritoneal Cavity/cytology , Animals , Antibodies, Monoclonal/administration & dosage , Antibodies, Monoclonal/immunology , Cell Count , Cell Movement , Cell Wall/chemistry , Eosinophilia/etiology , Eosinophils/physiology , Glucans/isolation & purification , Male , Mice , Mice, Inbred C57BLABSTRACT
An alkali-insoluble fraction 1 (F1), which contains mainly á-glucan isolated from the cell wall of Histoplasma capsulatum, induces eosinophil recruitment into the peritoneal cavity of mice. The present study was carried out to determine the participation of interleukin-5 (IL-5) in this process. Inbred C57BL/6 male mice weighing 15-20 g were treated ip with 100 µg of anti-IL-5 monoclonal antibody (TRFK-5, N = 7) or an isotype-matched antibody (N = 7), followed by 300 µg F1 in 1 ml PBS ip 24 h later. Controls (N = 5) received only 1 ml PBS. Two days later, cells from the peritoneal cavity were harvested by injection of 3 ml PBS and total cell counts were determined using diluting fluid in a Neubauer chamber. Differential counts were performed using Rosenfeld-stained cytospin preparations. The F1 injection induced significant (P < 0.01) leukocyte recruitment into the peritoneal cavity (8.4 x 10(6) cells/ml) when compared with PBS alone (5.5 x 10(6) cells/ml). Moreover, F1 selectively (P < 0.01) induced eosinophil recruitment (1 x 10(6) cells/ml) when compared to the control group (0.07 x 10(6) cells/ml). Treatment with TRFK-5 significantly (P < 0.01) inhibited eosinophil recruitment (0.18 x 10(6) cells/ml) by F1 without affecting recruitment of mononuclear cells or neutrophils. We conclude that the F1 fraction of the cell wall of H. capsulatum induces peritoneal eosinophilia by an IL-5-dependent mechanism. Depletion of this cytokine does not have effect on the recruitment of other cell types induced by F1.
Subject(s)
Animals , Male , Mice , Antibodies, Monoclonal , Eosinophilia , Glucans , Histoplasma , Interleukin-5 , Peritoneal Cavity , Antibodies, Monoclonal , Cell Count , Cell Movement , Cell Wall , Glucans , Mice, Inbred C57BLABSTRACT
Toxocariasis is an infection induced by Toxocara canis, an intestinal parasite of dogs. In this study, an experimental murine model of toxocariasis was used to evaluate the anti-inflammatory activity of an ethanolic extract of Lafoensia pacari stem bark. Mice infected with T. canis were treated with L. pacari extract (200 mg/kg, p.o.). Subsequently, we observed a reduction in the number of eosinophils in the peritoneal cavity, bronchoalveolar fluid, blood and bone marrow. Production of interleukin (IL)-5, a major cytokine involved in eosinophilic differentiation, proliferation and activation, is also an important marker for infection. The reduced levels of IL-5 observed in serum, lung homogenates and bronchoalveolar fluid demonstrated the anti-inflammatory mechanisms of L. pacari. Larvae recovery from infected mice treated with L. pacari was comparable with that from untreated mice, suggesting that L. pacari is not toxic to the parasite. Nonetheless, our results demonstrate a potential therapeutic effect of L. pacari extract in IL-5-mediated inflammatory diseases and provide new prospects for the development of drugs to treat IL-5-dependent allergic diseases such as parasite infection and asthma.
Subject(s)
Interleukin-5/biosynthesis , Magnoliopsida , Phytotherapy , Toxocariasis/drug therapy , Animals , Bone Marrow Cells/immunology , Bronchoalveolar Lavage Fluid/cytology , Bronchoalveolar Lavage Fluid/immunology , Eosinophils/immunology , Female , Interleukin-5/blood , Larva , Leukocyte Count , Leukocytes, Mononuclear/immunology , Lung/immunology , Mice , Peritoneal Cavity/cytology , Plant Extracts/therapeutic use , Toxocariasis/immunology , Toxocariasis/parasitologyABSTRACT
Histoplasma capsulatum is a fungus found intracellularly in neutrophils and peripheral blood mononuclear cells (PBMCs), suggesting that it is capable of evading damage and survives inside these cells. In this study, we report that neutrophils from H. capsulatum-infected mice, and human neutrophils and mononuclear cells exposed to H. capsulatum presented less apoptosis than those from noninfected animals or cells exposed to medium only. Moreover, cells harvested from infected animals are resistant to apoptosis induced by dexamethasone - a proapoptotic stimulant. We also show that neutrophils harvested from infected mice and PBMCs from humans exposed to the fungus had a greatly decreased Mac-1 expression. We conclude that H. capsulatum induces an antiapoptotic state on leucocytes, which correlates with decreased cell-surface Mac-1 expression. These facts may represent an escape mechanism for the fungus by delaying cell death and allowing the fungus to survive inside leucocytes.
Subject(s)
Apoptosis , Gene Expression Regulation, Fungal , Histoplasma/physiology , Leukocytes, Mononuclear/microbiology , Macrophage-1 Antigen/biosynthesis , Neutrophils/microbiology , Animals , Apoptosis/drug effects , Chemotaxis, Leukocyte , Dexamethasone/pharmacology , Female , Histoplasmosis/immunology , Histoplasmosis/pathology , Humans , Leukocytes, Mononuclear/metabolism , Macrophage-1 Antigen/genetics , Mice , Neutrophils/metabolism , Peritonitis/immunology , Peritonitis/microbiology , Peritonitis/pathologyABSTRACT
Development and evaluation of new vaccines and immunotherapy against tuberculosis demand a better understanding of the immune mechanisms in this disease. Costimulatory signals and intercellular contact seem to be pivotal in determining whether recognition of antigen by T cells leads to activation or anergy. In this paper, we show that virulent M. tuberculosis H37Rv downmodulates the ex vivo expression of CD18 and CD86 on peritoneal macrophages and VLA-4 on lymphocytes but does not disturb the in vitro production of interleukin (IL)-12 and interferon (IFN)-gamma after intraperitoneal infection. In addition, splenocytes from infected mice produce IL-10, while the expression of cell surface receptors is unchanged. The interplay among IL-12, IFN-gamma and IL-10 in vivo and the downmodulation of cell-surface receptors during the infection at the inflammatory site may contribute to the explanation of the maintenance of infection.
Subject(s)
Antigens, CD/metabolism , CD18 Antigens/metabolism , Integrins/metabolism , Lymphocytes/immunology , Macrophages, Peritoneal/immunology , Membrane Glycoproteins/metabolism , Peritonitis, Tuberculous/immunology , Receptors, Lymphocyte Homing/metabolism , Animals , B7-2 Antigen , Down-Regulation , In Vitro Techniques , Integrin alpha4beta1 , Interferon-gamma/biosynthesis , Interleukin-10/biosynthesis , Interleukin-12/biosynthesis , Lymphocyte Activation , Mice , Mice, Inbred BALB C , Mycobacterium tuberculosis/pathogenicityABSTRACT
1. The inflammatory cell influx towards the peritoneal cavity in mice inoculated i.p. with live or dead Histoplasma capsulatum or with its subcellular preparations was studied. We also evaluated the effects of dexamethasone (Dexa) or MK886, an inhibitor of leukotriene (LT) biosynthesis, on the recruitment of leukocytes. 2. Live yeast form of fungus (LYH) induced an increase in neutrophils (NE) which was highest 4 to 24 h after inoculation. Mononuclear cell (MN) migration beginning at 24 h with a gradual increase over 48 and 168 h, and an eosinophil (EO) recruitment occurs between 24 and 48 h. 3. NE and EO recruitment induced by dead mycelial form of fungus (DMH) was greater than that observed for dead yeast form of fungus (DYH). A similar leukocyte migration pattern was seen after i.p. injection of the alkali-insoluble fraction (F1) from DYH (F1Y) and F1 from DMH (F1M) this being more active than former. The difference in concentration of beta-glucan in DYH and DMH could explain the different inflammatory capacity exhibited by the two forms of H. capsulatum. 4. LT seems to be the principal mediator of leukocyte migration in response to LYH, DYH or DMH or to beta-glucan. However, other mediators appear to contribute to NE and EO migration since the treatment with Dexa was more effective in inhibiting cell migration than MK886. Complement dependent leukocyte migration may participate in this recruitment. Treatment with MK886 completely abolished MN cell migration, indicating its dependence on the presence of LT.
Subject(s)
Chemotaxis, Leukocyte , Glucans/immunology , Histoplasma/immunology , Leukocytes/microbiology , Leukotrienes/physiology , Animals , Anti-Inflammatory Agents/pharmacology , Cell Wall/immunology , Cell Wall/metabolism , Chemotaxis, Leukocyte/drug effects , Dexamethasone/pharmacology , Female , Glucans/metabolism , Histoplasma/metabolism , Histoplasmosis/immunology , Histoplasmosis/microbiology , Indoles/pharmacology , Leukocytes/drug effects , Leukotriene Antagonists/pharmacology , Leukotrienes/biosynthesis , Leukotrienes/metabolism , Mice , Neutrophil Infiltration/drug effectsABSTRACT
Serum and BALF (bronchoalveolar lavage fluid) IL-8 levels and serum levels were investigated in Toxocara canis infected guinea-pigs and the role of IL-5 as a modulator of cytokine secretion was studied. Serum levels increased early in infected animals, exceeding control levels 4 h after infection, peaked between days 6 and 18, and continued to exceed control levels after 48 days of infection. Serum and BALF IL-8 levels showed the same profile as blood eosinophilia, increasing 6 days post-infection and peaking between days 18 and 24. Treatment of infected animals with anti-IL-5 Ab suppressed eosinophilia with a parallel increase in blood IL-8 levels, whereas no change was found in levels. To support our in vivo observation we carried out experiments in vitro using guinea-pig LPS-stimulated adherent peritoneal cells which release large amounts of IL-8 into the supernatants. When rIL-5 was added to LPS-stimulated cells, 65% inhibition of IL-8 release into the supernatants was observed. Pre-incubation of cells with anti-IL-5 Ab prevented the inhibition of IL-8 release into the supernatants induced by rIL-5. Our results demonstrate for the first time that TNF-alpha and IL-8 are released concomitant with or after IL-5 in the eosinophilic inflammation induced by T. canis. Moreover, in addition to showing that IL-5 is fundamental for the induction of blood eosinophilia, the present results suggest that this cytokine may play a new biological role by acting as modulator of IL-8 secretion.
Subject(s)
Eosinophils/metabolism , Interleukin-5/metabolism , Interleukin-8/metabolism , Toxocara canis/immunology , Toxocariasis/metabolism , Animals , Antibodies/metabolism , Blood Cell Count , Bronchoalveolar Lavage Fluid , Down-Regulation , Eosinophils/cytology , Eosinophils/immunology , Female , Femur/metabolism , Guinea Pigs , Toxocariasis/blood , Toxocariasis/immunology , Tumor Necrosis Factor-alpha/metabolismABSTRACT
In this review we discuss our recently results showing interleukin 5 (IL-5) involvement in eosinophil migration and in the maintenance of eosinophilia in blood, bone marrow, lung and peritoneal cavity, in a visceral larva migrans syndrome model using guinea-pigs infected with Toxocara canis. We also describe the sequential release of TNF-alpha and IL-8 during the course of infection. Finally we propose a biological role for IL-5, at least in our model, as a modulator of IL-8 release and secretion.