Tumor necrosis factor and macrophage activation are important in clearance of Nocardia brasiliensis from the livers and spleens of mice

The roles of tumor necrosis factor (TNF) and macrophage activation in clearance of Nocardia brasiliensis from BALB/c mouse livers and spleens were evaluated. TNF activity was detectable in sera from animals at all stages of infection. Treatment of infected mice with an antiserum against TNF significantly enhanced the experimental infection as judged by enumeration of CFU in the spleens and livers of infected mice. In another set of experiments, a population of activated macrophages from the peritoneal cavities of N. brasiliensis-infected mice was studied by using a cytostatic assay. The observed cytotoxic activity of these activated macrophages against L929 cells was mediated by TNF, since this activity was inhibited by anti-TNF antiserum treatment. The level of TNF activity generated in vitro in the presence of lipopolysaccharide (LPS) by peritoneal macrophages from infected mice was higher than that of adherent peritoneal cells obtained from normal mice after challenge with LPS. When the nocardiacidal activity of peritoneal cells from N. brasiliensis-infected mice was estimated in vitro, a significant decrease in the number of CFU recovered was observed. Moreover, nocardiacidal activity of peritoneal cells obtained from N. brasiliensis-infected mice previously treated with anti-TNF antiserum was significantly reduced compared with the activity of cells obtained from infected mice previously treated with normal rabbit serum and that of cells from uninfected mice. These data suggest a role for TNF in resistance to N. brasiliensis infection.

Detection of cellular immunity with the soluble antigen of the fungus Sporothrix schenckii in the systemic form of the disease

Sporothrix schenckii is the etiologic agent of sporotrichosis, a mycosis of world-wide distribution more commonly occurring in tropical regions. The immunological mechanisms involved in the prevention and control of sporotrichosis are not fully understood but apparently include both the humoral and cellular responses. In the present investigation, cellular immunity was evaluated by in vivo and in vitro tests in mice infected with yeast-like forms of S. schenckii. The disease developed systemically and cellular immunity was evaluated for a period of 10 weeks. The soluble antigen utilized in the tests was prepared from yeast form of the fungus through the sonication (20 min: 10 sonications at 50 W at 2-min intervals). Delayed hypersensitivity and lymphocyte transformation tests showed that the cellular immune response was depressed between the 4th and 6th week of infection when the animals were challenged with the soluble fungal antigen. This depression frequently indicates worsening of the disease, with greater involvement of the host. This is a promising field of research for a better understanding of the pathogeny of this mycosis.

Mycobacterium leprae 65hsp antigen expressed from a retroviral vector in a macrophage cell line is presented to T cells in association with MHC class II in addition to MHC class I

Mycobacterium leprae lives free in the cytoplasm in infected macrophages. To test if an M. leprae antigen released into the cytoplasm would associate with major histocompatibility complex (MHC) class II we introduced the gene encoding the 65 kDa heat-shock protein (ML65hsp) into a retroviral shuttle vector (pZIPNeoSV(X)) and transfected the murine macrophage cell line J774G8. S1 nuclease mapping and Western blot analysis of the transfected cell line (CJ11) showed that specific messenger RNA and ML65hsp antigen were stably expressed. Presence of antigen at the cell surface was demonstrated by flow cytometric analysis with specific monoclonal antibodies (mAb). Antigen-specific T lymphocytes were stimulated by CJ11 cells to proliferate and release interleukins (IL-2 and IL-3). These responses were blocked by mAbs specific for either MHC class II or for the mycobacterial antigen. The endogenous antigen was also recognised by MHC class I-dependent cytotoxic T cells; cytotoxicity was inhibited by mAbs against either MHC class I molecules or ML65hsp. Thus, production of ML65hsp within the host cytoplasm resulted in association of the antigen with both MHC class I and MHC class II antigen-presenting structures and evoked both lymphocyte proliferation and cytotoxicity towards the antigen-presenting cell. These findings may be relevant to the development of recombinant subunit vaccines against intracellular pathogens.

Tumor necrosis factor (cachectin) mediates induction of cachexia by cord factor from mycobacteria

The mechanism by which cord factor (CF), a toxic glycolipid from mycobacteria, induces cachexia was studied in BALB/c mice. Body weight was markedly reduced 48 h after CF administration; the animals became severely wasted and exhibited hypertriglyceridemia, hypoglycemia, and high levels of tumor necrosis factor (TNF) in plasma. After CF administration, a transferable factor which caused cachexia and hypertriglyceridemia in recipient mice was detected in the blood. Dexamethasone partially inhibited the cachexia-inducing action of CF. Conditioned medium from adherent peritoneal cell cultures incubated with CF produced the same wasting symptoms when inoculated intravenously into mice. These studies also demonstrated that adherent peritoneal cells produced a humoral factor in response to CF which was related to CF-induced cachexia. Antiserum to recombinant TNF-alpha prevented the cachectin action in passive-transfer experiments. Our findings indicate that cachectin (TNF) plays a role as a central mediator of the wasting induced by CF.

Mouse cachexia induced by trehalose dimycolate from Nocardia asteroides

Trehalose dimycolate (TDM) isolated from Nocardia asteroides induced in mice a severely wasted condition known as cachexia. Intraperitoneal injection of mice with five 10 micrograms doses of TDM in mineral oil at intervals of 2 d killed 90% of the animals within 26 d. Death followed a precipitous weight loss and an inflammatory process in the peritoneal cavity. When mice were injected intraperitoneally with a single 10 micrograms dose of TDM, 48 h later, they had begun to lose weight and exhibited extreme hypertriglyceridaemia and hypoglycaemia. Tumour necrosis factor (or cachectin) was detected in the plasma from animals injected with TDM. This cytokine released by mononuclear phagocytes may be involved in the induction of cachexia by TDM.

Studies on the pathogenesis of actinomycotic mycetoma in animals injected with fractions isolated from Nocardia brasiliensis

In the present study the participation was evaluated of isolated fractions of Nocardia brasiliensis in the genesis of the inflammatory response observed in actinomycotic mycetoma. Subcutaneous injection in mice of a suspension containing a polysaccharide fraction F1 obtained by treating cell walls with sodium hydroxide induced an inflammatory response at the inoculation site which was characterized by a large influx of polymorphonuclear (PMN) and mononuclear (MN) leucocytes between the 2nd and 4th days. On the 8th day, a typical granulomatous reaction was observed involving large numbers of epithelioid cells. Intravenous injection of the lipid extract adsorbed to charcoal particles into mice induced an inflammatory reaction around the particles embolized in the pulmonary microcirculation which was similar to that described above. The kinetics of the inflammatory cell migration was studied by total and differential counts of leukocytes that migrated to the peritoneal cavity of rats inoculated intraperitoneally with the F1 and lipid fractions. Both fractions initially induced intense PMN migration, which was later reduced, with a simultaneous increase in mononuclear cells. The present results demonstrate that a polysaccharide fraction (F1) and the lipid fraction reproduce the fundamental lesion of actinomycotic mycetoma.

The role of fractions from Paracoccidioides brasiliensis in the genesis of inflammatory response

The influx of inflammatory cells towards the peritoneal cavity in rats inoculated intraperitoneally with subcellular preparations of the fungus Paracoccidioides brasiliensis was studied. In addition to the dead fungus, also fractions F1 of the cell wall, which mainly consisted of polysaccharides and the lipid extract, induced intense cell migration 4 hr after inoculation, with a greatly increased number of polymorphonuclear leucocytes (PMN). Study of the kinetics of cell influx showed that both fraction F1 and the lipid extract initially induced intense PMN migration between the 4th and 24th hr after inoculation of these agents, followed by migration of mononuclear cells (MN) around the 48th hr. We also observed that migration of these cells increased gradually after inoculation of growing doses of fraction F1. The present data suggest that polysaccharides and lipids isolated from P. brasiliensis may participate in the initial phase of the inflammatory response in paracoccidioidomycosis.

Mouse toxicity induced by lipids and cell walls isolated from actinomycetes

The possibility was examined that the toxicity induced in mice by Actinomadura madurae, 'Streptomyces pelletieri' and Nocardia brasiliensis was due to lipid and cell-wall constituents. Mice were inoculated intraperitoneally with heat-killed bacteria, lipid extracts and cell-wall preparations emulsified in mineral oil: toxicity was evaluated by recording weight loss and deaths. Killed cells and cell-wall preparations of all three actinomycetes produced a pronounced loss of body weight, tissue necrosis, splenomegaly, a granulomatous inflammation and sometimes death. Mice inoculated with lipid extracts from A. madurae and 'S. pelletieri' neither died nor showed toxic effects, but mice injected with lipids isolated from N. brasiliensis did suffer toxic effects. They showed more marked wasting symptoms than observed after inoculation of heat-killed bacteria or of the cell-wall preparation.

Cord factor is associated with the maintenance of the chronic inflammatory reaction caused by mycobacteria

The distribution of an aqueous suspension of cord factor (CF) from Mycobacterium bovis BCG in several mouse organs was examined after intravenous injection, and the correlation between evolution of the inflammatory granulomatous reaction and the presence of CF in these organs was determined. CF was preferentially deposited in the lungs and liver, and the kinetics of the pulmonary and hepatic inflammatory reaction, evaluated by determining the indices for these organs, showed a gradual increase on day 2 after injection, reached a peak around the fifth day, and declined thereafter. Histological analysis showed that on day 5 both the lungs and the liver were diffusely damaged by a mononuclear inflammatory infiltrate arranged in a granulomatous manner and consisting predominantly of histiocytes. CF elimination was more marked in the liver than in the lungs: 2 d after injection 76% of the material deposited in the liver had been eliminated. Little or no CF was detected in the liver and lungs by day 16, when the inflammatory reaction was also substantially decreased. A second CF dose administered 8 d after the first exacerbated the inflammatory process in both the lungs and the liver, indicating that the intensity of this process depends on CF concentration in the lesion site.

Role of the fungal cell wall in the granulomatous response of mice to the agents of chromomycosis

Mice were given, intraperitoneally, inocula of a cell-wall preparation and fractions thereof from Fonsecaea pedrosoi, F. compactum, Cladosporium carrioni and Phialophora verrucosum. Large doses of cell-wall preparation, with or without trypsin treatment, produced a pronounced loss of body weight, a granulomatous reaction and, sometimes, death. After extraction of the cell wall preparation with 1N NaOH, three fractions were obtained: an alkali-insoluble fraction 1; an alkali-soluble acid-insoluble fraction 2; and an alkali- and acid-soluble fraction 3. Intravenous administration showed that only fraction 1 induced a granulomatous reaction and death in mice.

A Paracoccidioides brasiliensis polysaccharide having granuloma-inducing, toxic and macrophage-stimulating activity

The occurrence of a polysaccharide fraction of Paracoccidioides brasiliensis cell wall with toxic, granuloma-inducing and macrophage-stimulating activities was demonstrated. After fractionation of the lipid-extracted wall with 1 M-NaOH, three fractions were obtained: (1) an alkali-insoluble fraction; (2) an alkali-soluble, acid-insoluble fraction and (3) an alkali-soluble, acid-soluble fraction. When the three fractions were injected into mice only fraction (1) was able to induce chronic lung inflammation, causing a marked loss in body weight and death at a dose of 6 mg per animal. Analysis of the stimulation of peritoneal macrophages of mice (measured by cell spreading on glass) after intraperitoneal injection of fraction 1 showed that 75% of the cells were able to spread even 20 d after inoculation.

Role of cord factor in the modulation of infection caused by mycobacteria

The subcutaneous, intradermal, and pulmonary inflammatory lesions induced in mice by viable Mycobacterium bovis (BCG) with no glycolipid cord factor (CF) on the outer cell wall (delipidated BCG, dBCG) was drastically different from that induced by inoculation with intact bacteria. The reaction caused by dBCG was of an acute nature: the cells making up the inflammatory infiltrate exhibited polymorphonuclear-like (PMNs) morphologic characteristics, there was a decrease on delayed hypersensitivity response, and the lesion was resolved around the 16th day after inoculation. Complete disappearance of viable organisms from the lungs, liver, and spleen of these animals occurred in parallel with the dissipation of the dBCG-induced inflammatory infiltrate, showing that CF plays an important role in the host-parasite relationship that takes place in infections caused by mycobacteria. In addition, when deprived of this glycolipid component, bacilli lose their immunostimulant ability.

Granulomatous reactions induced by lipids extracted from Fonsecaea pedrosoi, Fonsecaea compactum, Cladosporium carrionii and Phialophora verrucosum

Granulomatous reactions induced by lipid extracts from the dermatophyte fungi Fonsecaea pedrosoi, Fonsecaea compactum, Cladosporium carrionii and Phialophora verrucosum, the causal organisms of chromoblastomycosis, were studied. Charcoal particles coated with the lipid extracts were prepared and injected intravenously into mice. Inflammation was characterized by an intense mononuclear cell infiltrate that lodged in the lung from 4 to 8 d after inoculation.

Granulomatous reaction induced by lipids isolated from Paracoccidioides brasiliensis

The possibility that the histological responses produced in paracoccidioidomycosis might be attributed to lipid constituents of cells of Paracoccidioides brasiliensis was investigated. Charcoal particles coated with the lipid extract were prepared and the suspension inoculated intravenously into mice. The lung inflammation was characterized by an intense mononuclear and polymorphonuclear cell infiltrate surrounding the particles from two to eight days after inoculation. Fractionation of lipid extract by preparative thin-layer chromatography allowed the separation of several fractions and it was observed that fractions containing free fatty acids and triglycerides were the most active. The participation of an uncommon fatty acid eliciting an inflammatory reaction is discussed.

Purification of 1-monoacylglycerols containing alpha-branched-beta-hydroxylated fatty acids from lipids of Corynebacterium pseudotuberculosis

A complex mixture of monoacylglycerols, identified as (C30--C36) corynomycoloylglycerols was isolated from the diethyl ether/acetone-soluble lipids of Corynebacterium pseudotuberculosis.