Celecoxib treatment dampens LPS-induced periapical bone resorption in a mouse model

AIM

To evaluate the efficacy of selective and nonselective inhibitors of cyclooxygenase-2 enzymes in the treatment of experimental apical periodontitis induced by bacterial lipopolysaccharide (LPS) in vivo in a mouse model.

METHODOLOGY

Thirty-six C57BL/6 mice were used. After access cavity preparation, a solution containing E. coli LPS (1.0 µg µL^-1 ) was inoculated into the root canals of the mandibular and maxillary right first molars (n = 72) After 30 days, apical periodontitis was established and the animals were systemically treated with celecoxib, a selective COX-2 inhibitor (15 mg kg^-1 ), or indomethacin, a nonselective COX-2 inhibitor (5 mg kg^-1 ), for 7 and 14 days. Blocks containing teeth and bone were removed for histopathological and histometric analyses (haematoxylin and eosin), evaluation of osteoclasts numbers (tartrate-resistant acid phosphatase enzyme - TRAP) and immunohistochemistry for RANK, RANKL and OPG. Gene expression was performed using reverse transcription and real-time polymerase chain reaction (qRT-PCR) for RANK, RANKL, OPG, TRAP, MMP-9, cathepsin K and calcitonin receptor. Histopathological, histometric, TRAP, immunohistochemistry and qRT-PCR data were evaluated using Kruskal-Wallis followed by Dunn's test (α = 0.05).

RESULTS

Systemic administration of celecoxib for 7 and 14 days prevented periapical bone resorption (P < 0.0001), differently from indomethacin that exacerbated bone resorption at 7 days (P < 0.0001) or exerted no effect at 14 days (P = 0.8488). Celecoxib treatment reduced osteoclast formation in apical periodontitis, regardless of the period of treatment (P < 0.0001 for 7 days and P = 0.026 for 14 days). Administration of celecoxib or indomethacin differentially modulated the expression of genes involved in bone resorption. At 7 days, celecoxib and indomethacin treatment significantly inhibited expression of mRNA for cathepsin K (P = 0.0005 and P = 0.016, respectively) without changing TRAP, MMP-9 and calcitonin receptor gene expression. At 14 days, celecoxib significantly inhibited expression of mRNA for MMP-9 (P < 0.0001) and calcitonin receptor (P = 0.004), whilst indomethacin exerted no effect on MMP-9 (P = 0.216) and calcitonin receptor (P = 0.971) but significantly augmented cathepsin K gene expression (P = 0.001).

CONCLUSIONS

The selective COX-2 inhibitor celecoxib reduced osteoclastogenic signalling and activity that dampened bone resorption in LPS-induced apical periodontitis in mice, with greater efficacy than the nonselective inhibitor indomethacin.

Effects of natural aging and gender on pro-inflammatory markers

The term inflammaging is now widely used to designate the inflammatory process of natural aging. During this process, cytokine balance is altered, presumably due to the loss of homeostasis, thus contributing to a greater predisposition to disease and exacerbation of chronic diseases. The aim of the study was to analyze the relationship between pro-inflammatory markers and age in the natural aging process of healthy individuals. One hundred and ten subjects were divided into 5 groups according to age (22 subjects/group). Interleukin-6 (IL-6) and tumor necrosis factor α (TNF-α) were quantified using the ELISA method. High-sensitivity C-reactive protein (hsCRP) was analyzed by turbidimetry according to laboratory procedures. The main findings of this study were: a positive correlation between hsCRP and IL-6 as a function of age (110 subjects); women showed stronger correlations; the 51–60 age group had the highest values for hsCRP and IL-6; women presented higher values for hsCRP in the 51–60 age group and higher values for IL-6 in the 61–70 age group; and men showed higher values in the 51–60 age group for hsCRP and IL-6. In conclusion, the natural aging process increased IL-6 and hsCRP levels, which is consistent with the inflammaging theory; however, women presented stronger correlations compared to men (IL-6 and hsCRP) and the 51–60 age range seems to be a key point for these increases. These findings are important because they indicate that early preventive measures may minimize the increase in these inflammatory markers in natural human aging.

Nanobiotechnological approaches to delivery of DNA vaccine against fungal infection

Vaccines play an essential role in keeping humans healthy. Innovative approaches to their use include the utilization of plasmid DNA encoding sequences to express foreign antigens. DNAhsp65 from Mycobacterium leprae is suitable for this purpose due to its ability to elicit a powerful immune response. Controlled release systems represent a promising approach to delivering vaccines. In this work, we used liposomes or PLGA systems to deliver DNAhsp65 to treat the pulmonary fungal infection Paracoccidioidomycosis. Both formulations modulated a protective immune response and reduced the pulmonary fungal burden even in the groups receiving less than four times the amount of the DNAhps65 entrapped within the nanoparticles. Although both systems had the same effective therapeutic results, the advantage of the liposome formulation was that it was administered intranasally, which may be more easily accepted by patients. These systems are a great alternative to be considered as adjuvant vaccine therapy for systemic mycosis.

Evidence for eosinophil recruitment, leukotriene B4 production and mast cell hyperplasia following Toxocara canis infection in rats

It is well known that eosinophilia is a key pathogenetic component of toxocariasis. The objective of the present study was to determine if there is an association between peritoneal and blood eosinophil influx, mast cell hyperplasia and leukotriene B(4) (LTB(4)) production after Toxocara canis infection. Oral inoculation of 56-day-old Wistar rats (N = 5-7 per group) with 1000 embryonated eggs containing third-stage (L3) T. canis larvae led to a robust accumulation of total leukocytes in blood beginning on day 3 and peaking on day 18, mainly characterized by eosinophils and accompanied by higher serum LTB(4) levels. At that time, we also noted increased eosinophil numbers in the peritoneal cavity. In addition, we observed increased peritoneal mast cell number in the peritoneal cavity, which correlated with the time course of eosinophilia during toxocariasis. We also demonstrated that mast cell hyperplasia in the intestines and lungs began soon after the T. canis larvae migrated to these compartments, reaching maximal levels on day 24, which correlated with the complete elimination of the parasite. Therefore, mast cells appear to be involved in peritoneal and blood eosinophil infiltration through an LTB(4)-dependent mechanism following T. canis infection in rats. Our data also demonstrate a tight association between larval migratory stages and intestinal and pulmonary mast cell hyperplasia in the toxocariasis model.

Leukotrienes are not essential for the efficacy of a heterologous vaccine against Mycobacterium tuberculosis infection

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.

Evaluation of environmental mycobacteria contamination in a specific pathogen free animal facility from a tropical country

With the evidence showing the protection variability of bacille Calmette-Guérin, new potential vaccines for tuberculosis have been tested around the world. One of the general concerns in tuberculosis vaccine development is the possibility of priming the host immune system with prior exposure to environmental mycobacteria antigens, which can change the efficacy of subsequent vaccination. As there is a great homology between the species from Mycobacterium genera, the previous contact of experimental animals with environmental mycobacteria could sensitize the mice and, in this way, could influence subsequent vaccine research. The aim of our study was to investigate critical points in an animal facility to search for environmental mycobacteria that eventually could be in direct or indirect contact with the experimental animals. Samples were collected from surfaces of walls, floor, animal cages and shelves and analysed using the Ogawa-Kudoh decontamination method. Samples of drinking water, food and sawdust were collected for analysis by the NALC/NaOH decontamination method. Also, the samples were cultivated directly in broth medium, without any method for decontamination. After decontamination methods, we observed bacterial colony growth in 4.31% of the total of samples analysed. These samples were stained with Ziehl-Neelsen and we did not detect any acid-fast bacilli, suggesting that the animal facility analysed is free from contamination by environmental mycobacteria and is not a source of mycobacterial antigens. Furthermore, our study showed a new paradigm in tuberculosis vaccine development: concern about the animal facility environment in terms of immune system priming of experimental animals by nascent bacterial contaminants.

Blocking central leukotrienes synthesis affects vasopressin release during sepsis

Recent studies revealed that vasopressinergic neurons have a high content of cys-leukotriene C(4) (LTC(4)) synthase, a critical enzyme in cys-leukotriene synthesis that may play a role in regulating vasopressin secretion. This study investigates the role of this enzyme in arginine vasopressin (AVP) release during experimentally induced sepsis. Male Wistar rats received an i.c.v. injection of 3-[1-(p-chlorobenzyl)-5-(isopropyl)-3-tert-butylthioindol-2-yl]-2, 2-dimethylpropanoic acid (MK-886) (1.0 microg/kg), a leukotrienes (LTs) synthesis inhibitor, or vehicle, 1 h before cecal ligation and puncture (CLP) or sham operation. In one group of animals the survival rate was monitored for 3 days. In another group, the animals were decapitated at 0, 4, 6, 18 and 24 h after CLP or sham operation, and blood was collected for hematocrit, serum sodium and nitrate, plasma osmolality, protein and AVP determination. A third group was used for blood pressure measurements. The neurohypophysis was removed for quantification of AVP content, and the hypothalamus was dissected for LTC(4) synthase analysis by Western blot. Mortality after CLP was reduced by the central administration of MK-886. The increase in plasma AVP levels and hypothalamus LTC(4) synthase content in the initial phase of sepsis was blocked, whereas the decrease in neurohypophyseal AVP content was partially reversed. Also the blood pressure drop was abolished in this phase. The increase of serum nitric oxide and hematocrit was reduced, and the decrease in plasma protein and osmolality was not affected by the LTs blocker. In the final phase of sepsis, the plasma AVP level and the hypothalamic LTC(4) synthase content were at basal levels. The central administration of MK-886 increased the hypothalamic LTC(4) synthase content but did not alter the plasma and neurohypophysis AVP levels observed, or the blood pressure during this phase. These results suggest that the central LTs are involved in the vasopressin release observed during sepsis.

Anti-eosinophilic effect of Lafoensia pacari in toxocariasis

We previously reported the anti-inflammatory activity of Lafoensia pacari extract in Toxocara canis infection, a model of systemic IL-5-dependent eosinophil migration. In the present study, we describe the kinetics of the anti-inflammatory activity of L. pacari extract and compare it with dexamethasone. T. canis-infected mice were submitted to different treatment protocols and the cells present in bronchoalveolar space and peritoneal cavity were collected at the end of each treatment period. The results showed that L. pacari extract effectively inhibited eosinophil migration only when the treatment was initiated before the peak of eosinophil migration (1st to 18th; 12th to 18th and 12th to 24th day post-infection). When eosinophil migration was established, administration of L. pacari extract had no effect on it (treatment 18th to 24th day post-infection). Dexamethasone was effective in inhibiting eosinophil migration in all periods studied. We suggest that L. pacari extract can potentially be a natural alternative treatment of eosinophilic diseases.

Nitric oxide synthase activity in tissues of the blowfly Chrysomya megacephala (Fabricius, 1794)

Although insects lack the adaptive immune response of the mammalians, they manifest effective innate immune responses, which include both cellular and humoral components. Cellular responses are mediated by hemocytes, and humoral responses include the activation of proteolytic cascades that initiate many events, including NO production. In mammals, nitric oxide synthases (NOSs) are also present in the endothelium, the brain, the adrenal glands, and the platelets. Studies on the distribution of NO-producing systems in invertebrates have revealed functional similarities between NOS in this group and vertebrates. We attempted to localize NOS activity in tissues of naïve (UIL), yeast-injected (YIL), and saline-injected (SIL) larvae of the blowfly Chrysomya megacephala, using the NADPH diaphorase technique. Our findings revealed similar levels of NOS activity in muscle, fat body, Malpighian tubule, gut, and brain, suggesting that NO synthesis may not be involved in the immune response of these larval systems. These results were compared to many studies that recorded the involvement of NO in various physiological functions of insects.

Impact of MK886 on Eosinophil Counts and Phenotypic Features in Toxocariasis

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.

Ultrasonically nebulized distilled water prevents exogenous histamine hyperreactivity in Toxocara canis-infected mice

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.

Immunotherapy with plasmid DNA encoding mycobacterial hsp65 in association with chemotherapy is a more rapid and efficient form of treatment for tuberculosis in mice

Tuberculosis (TB) remains a threat for public health, killing around 3 million people a year. Despite the fact that most cases can be cured with antibiotics, the treatment is long and patients relapse if chemotherapy is not continued for at least 6 months. Thus, a better characterization of the working principles of the immune system in TB and identification of new immunotherapeutic products for the development of shorter regimens of treatment are essential to achieve an effective management of this disease. In the present work, we demonstrate that immunotherapy with a plasmid DNA encoding the Mycobacterium leprae 65 kDa heat-shock protein (hsp65) in order to boost the efficiency of the immune system, is a valuable adjunct to antibacterial chemotherapy to shorten the duration of treatment, improve the treatment of latent TB infection and be effective against multidrug-resistant bacilli (MDR-TB). We also showed that the use of DNA-hsp65 alone or in combination with other drugs influence the pathway of the immune response or other types of inflammatory responses and should augment our ability to alter the course of immune response/inflammation as needed, evidencing an important target for immunization or drug intervention.

Differential release of MIP-1alpha and eotaxin during infection of mice by Histoplasma capsulatum or inoculation of beta-glucan

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

Interleukin-5 mediates peritoneal eosinophilia induced by the F1 cell wall fraction of Histoplasma capsulatum

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.

Lafoensia pacari extract inhibits IL-5 production in toxocariasis

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.

Disodium cromoglycate prevents ileum hyperreactivity to histamine in Toxocara canis-infected guinea pigs

The aim of this study was to investigate whether Toxocara canis infection in guinea pigs provokes changes in ileum responsiveness to histamine. Ileum segments from control and T. canis-infected groups were placed at isometric conditions and submitted to various doses of histamine. No changes were observed between controls and T. canis-infected groups at days 3, 6 and 12 after infection. However, at days 18 and 24 after infection, there was a significant increase in ileum responsiveness to histamine in T. canis-infected group. Pre-incubation of ileum segments with 1mgml(-1) disodium cromoglycate (DSCG) prevented the increased responsiveness to histamine in T. canis-infected guinea pigs and did not affect ileum contractility in non-infected animals. These results indicate that T. canis-infected guinea pigs develop increased intestinal responsiveness to histamine and that DSCG prevents alterations in smooth-muscle contractility.

Propolis: lymphocyte proliferation and IFN-gamma production

We evaluated propolis influence on polyclonal activation of lymphocytes by concanavalin A (Con A). The in vitro experiments showed that propolis decreases splenocyte proliferation both in the absence or presence of Con A. The suppression in mitogen-induced splenocyte proliferation also occurred when mice were treated intraperitoneally with propolis for 3 days. An increased of IFN-gamma production in the culture supernatants of the same cells was observed. A dual action of propolis on lymphocyte activation was proposed: it decreases splenocyte proliferation in the presence or absence of Con A and stimulates IFN-gamma production by spleen cells. These results are important to understand the immunomodulatory action of propolis on the host's specific and non-specific immunity.

Histoplasma capsulatum inhibits apoptosis and Mac-1 expression in leucocytes

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.

Inflammatory response to different endodontic irrigating solutions

AIM

The aim of this study was to evaluate the inflammatory response to irrigating solutions injected into the peritoneal cavity of mice.

METHODOLOGY

Sixty mice received intra-peritoneal injections of 0.3 mL of 0.5% sodium hypochlorite, 2.0% chlorhexidine digluconate or phosphate buffered saline (PBS, control). Five animals of each group were sacrificed at 4, 24, 48 h and 7 days after the injection. Liquid from the peritoneal cavity of each animal was collected for the total and differential counting of inflammatory cells and protein leakage.

RESULTS

The 0.5% sodium hypochlorite solution group had greater migration of neutrophils and mononuclear cells to the peritoneal cavity from 48 to 168 h (P < 0.05). There was a significant increase in protein leakage to the peritoneal cavity after 4 up to 48 h in the 0.5% sodium hypochlorite group compared to the control group. Protein leakage was similar in all groups at 168 h. The 2.0% chlorhexidine group had similar results to the control group at all time periods.

CONCLUSIONS

The 0.5% sodium hypochlorite solution induced an inflammatory response, however, the 2.0% chlorhexidine digluconate solution did not induce a significant inflammatory response.

Role of trehalose dimycolate in recruitment of cells and modulation of production of cytokines and NO in tuberculosis

Mice treated with viable Mycobacterium tuberculosis with no glycolipid trehalose dimycolate (TDM) on the outer cell wall (delipidated M. tuberculosis) by intraperitoneal or intratracheal inoculation presented an intense recruitment of polymorphonuclear cells into the peritoneal cavity and an acute inflammatory reaction in the lungs, respectively. In addition, lung lesions were resolved around the 32nd day after intratracheal inoculation. TDM-loaded biodegradable poly-DL-lactide-coglycolide microspheres as well as TDM-coated charcoal particles induced an intense inflammatory reaction. In addition, high levels of interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-alpha), IL-12, IL-10, gamma interferon (IFN-gamma), and IL-4 production were detected in lung cells, and nitric oxide (NO) production was high in culture supernatants of bronchoalveolar lavage cells. These in vivo data were confirmed by in vitro experiments using peritoneal macrophages cultured in the presence of TDM adsorbed onto coverslips. High levels of IFN-gamma, IL-6, TNF-alpha, IL-12, IL-10, and NO were detected in the culture supernatants. Our results suggest that TDM contributes to persistence of infection through production of cytokines, which are important for the recruitment of inflammatory cells and maintenance of a granulomatous reaction. In addition, our findings are important for a better understanding of the immunostimulatory activity of TDM and its possible use as an adjuvant in experiments using DNA vaccine or gene therapy against tuberculosis.

Comparison of different delivery systems of vaccination for the induction of protection against tuberculosis in mice

The way to deliver antigens and cellular requirements for long-lasting protection against tuberculosis are not known. Immunizations with mycobacterial 65 kDa heat shock protein (hsp65) expressed from J774-hsp65 cells (antigen-presenting cells that endogenously produce hsp65 antigen) or from plasmid DNA, or with the protein entrapped in cationic liposomes, can each give protective immunity similar to that obtained from live Bacillus Calmette Guérin (BCG), whereas injecting the protein in Freund's incomplete adjuvant (FIA) has minimal effect. Protective procedures elicited high frequencies of antigen-reactive alphabeta T cells with CD4+/CD8- and CD8+/CD4- phenotypes. Protection correlated with the abundance of hsp65-dependent cytotoxic CD8+/CD4-/CD44hi cells. The frequency of these cells and the level of protection declined during 8 months after J774-hsp65 or liposome-mediated immunization with hsp65 protein but were sustained or steadily increased over this period after hsp65-DNA or BCG immunizations. IFN-gamma predominated over IL-4 among the hsp65-reactive CD8+/CD4- and CD4+/CD8- populations after J774-hsp65-, hsp65-liposome-, and hsp65-DNA-mediated immunizations, but similar levels of these cytokines prevailed after BCG vaccination.

Cytotoxic T cells and mycobacteria

How the immune system kills Mycobacterium tuberculosis is still a puzzle. The classical picture of killing due to phagocytosis by activated macrophages may be only partly correct. Based on recent evidence, we express here the view that cytotoxic T lymphocytes also make an important contribution and suggest that DNA vaccines might be a good way to enhance this.

Characterization of the memory/activated T cells that mediate the long-lived host response against tuberculosis after bacillus Calmette-Guérin or DNA vaccination

The memory/activated T cells, which mediate the long-lived host response against tuberculosis, in mice immunized with either bacillus Calmette-Guérin (BCG) or mycobacterium heat-shock protein 65 (hsp 65) antigen expressed from plasmid DNA (DNA-hsp 65), were characterized. Protection against Mycobacterium tuberculosis challenge by DNA-hsp 65 vaccination was associated with the presence of lymph node T-cell populations in which CD8+/CD44hi interferon-gamma (IFN-gamma)-producing/cytotoxic cells were prominent even after 8 or 15 months of plasmid DNA-mediated immunizations, whereas after BCG vaccination the majority were CD4+/CD44lo IFN-gamma-producing T cells. When the cells were separated into CD4+CD8- and CD8+CD4- and then into CD44hi and CD44lo types, CD44lo cells were essentially unable to transfer protection in adoptive transfer experiments, the most protective CD44hi cells were CD8+CD4- and those from DNA-vaccinated mice were much more protective than those from BCG-immunized mice. The frequency of protective T cells and the level of protection were increased up to 8 months and decreased after 15 months following DNA or BCG immunizations.

Therapy of tuberculosis in mice by DNA vaccination

Mycobacterium tuberculosis continues to kill about 3 million people every year, more than any other single infectious agent. This is attributed primarily to an inadequate immune response towards infecting bacteria, which suffer growth inhibition rather than death and subsequently multiply catastrophically. Although the bacillus Calmette-Guerin (BCG) vaccine is widely used, it has major limitations as a preventative measure. In addition, effective treatment requires that patients take large doses of antibacterial drug combinations for at least 6 months after diagnosis, which is difficult to achieve in many parts of the world and is further restricted by the emergence of multidrug-resistant strains of M. tuberculosis. In these circumstances, immunotherapy to boost the efficiency of the immune system in infected patients could be a valuable adjunct to antibacterial chemotherapy. Here we show in mice that DNA vaccines, initially designed to prevent infection, can also have a pronounced therapeutic action. In heavily infected mice, DNA vaccinations can switch the immune response from one that is relatively inefficient and gives bacterial stasis to one that kills bacteria. Application of such immunotherapy in conjunction with conventional chemotherapeutic antibacterial drugs might result in faster or more certain cure of the disease in humans.

Cytokines in the modulation of eosinophilia

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.

Participation of interleukin-5, interleukin-8 and leukotriene B4 in eosinophil accumulation in two different experimental models

There are several experimental models describing in vivo eosinophil (EO) migration, including ip injection of a large volume of saline (SAL) or Sephadex beads (SEP). The aim of this study was to investigate the mechanisms involved in the EO migration in these two models. Two consecutive injections of SAL given 48 hr apart, induced a selective recruitment of EO into peritoneal cavity of rats, which peaked 48 hr after the last injection. SEP, when injected ip, promoted EO accumulation in rats. The phenomenon was dose-related and peaked 48 hr after SEP injection. To investigate the mediators involved in this process we showed that BW A4C, MK 886 and dexamethasone (DXA) inhibited the EO migration induced by SAL and SEP. To investigate the source of the EO chemotactic factor we showed that mast cells, macrophages (MO), but not lymphocytes, incubated in vitro in presence of SAL released a factor which induced EO migration. With SEP, only mast cells release a factor that induced EO migration, which was inhibited by BW A4c, MK 886 and DXA. Furthermore, the chemotactic activity of SAL-stimulated mast cells was inhibited by antisera against IL-5 and IL-8 (interleukins). SAL-stimulated MO were only inhibited by anti-IL-8 antibodies as well SEP-stimulated mast cells. These results suggest that the EO migration induced by SAL may be dependent on resident mast cells and MO and mediated by LTB4, IL-5 and IL-8. SEP-induced EO migration was dependent on mast cells and may be mediated by LTB4 and IL-8. Furthermore, IL-5 and IL-8 induced EO migration, which was also dependent on resident cells and mediated by LTB4. In conclusion, EO migration induced by SAL is dependent on mast cells and MO, whereas that induced by SEP is dependent on mast cells alone. Stimulated mast cells release LTB4, IL-5 and IL-8 while MO release LTB4 and IL-8. The IL-5 and IL-8 release by the SAL or SEP-stimulated resident cells may act in an autocrine fashion, thus potentiating LTB4 release.

Interleukin-5 modulates interleukin-8 secretion in eosinophilic inflammation

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.

Inflammatory response to calcium hydroxide based root canal sealers

This study evaluated the inflammatory response to Sealapex, CRCS, Apexit, and Sealer 26 in the subcutaneous tissue and in peritoneal cavity of Balb/c mice. The inflammatory response of subcutaneous tissue was analyzed after 2, 4, 8, and 16 days. Intense neutrophilia was seen in response to all sealers during the initial periods. Differences among them related to the presence of necrosis and the number of inflammatory cells. In the intermediate phase marked differentiation of cells of the mononucleate phagocytic system into macrophages, epithelioid cells and multinucleate giant cells were observed with Sealapex. This response was less intense with CRCS and Apexit. Tissue necrosis was observed only at tissue sealer interfaces and only during the initial period with Sealapex but was seen throughout the experiment with all other sealers. The animals were injected in the peritoneal cavity with solutions containing the sealers and five mice from each group were killed 6 and 24 h, and 5 and 15 days later. During the initial periods (6 and 24 h) there was an intense migration of polymorphonuclear leukocytes to the peritoneal cavity in response to all sealers compared to the control. This migration was more intense for Sealer 26 and Apexit. An increase in mononucleate cell number was observed after 6 and 24 h and 5 days for all sealers and no differences were observed in relation to the control after 15 days.

Participation of interleukin-5 and interleukin-8 in the eosinophil migration induced by a large volume of saline

Recently we demonstrated that the eosinophil migration into rat peritoneal cavities induced by a large volume of saline is mediated by LTB4 released by the resident macrophages and mast cells. In the present study, we have investigated the involvement of IL-5 and IL-8 in this process. We observed that saline-stimulated mast cells released the eosinophil chemotactic cytokines IL-5 and IL-8, while macrophages released only IL-8. These observations were confirmed by the ability of antibodies against IL-5 and IL-8 block the eosinophil chemotactic activity of the mast cell supernatants while the chemotactic activity of the macrophage supernatants was inhibited only by the antibody to IL-8. Recombinant forms of IL-5 and IL-8, when injected intraperitoneally, induced a dose-dependent eosinophil accumulation in naïve rats. The mechanism by which these cytokines induce eosinophil migration seems to be dependent on the resident cell population since depleting the peritoneal cavities of the latter renders the animals unresponsive to the eosinophil recruitment when challenged with IL-5, IL-8 or the supernatants of saline-treated mast cells or macrophages. Dexamethasone and MK 886 blocked the eosinophil migration induced by both the supernatants of saline-stimulated mast cells or macrophages and by IL-5 or IL-8. The IL-5-induced eosinophil migration was also blocked by BW A4C, another lipoxygenase inhibitor. Together, these results suggest LTB4 to be the lipoxygenase metabolite involved in the eosinophil recruitment induced by IL-5 and IL-8. Our results indicate that the eosinophil migration induced by saline is a complex phenomenon which is dependent on the resident mast cells and macrophages and is mediated by LTB4, IL-5 and IL-8. Mast cells release LTB4, IL-5 and IL-8, whereas macrophages release mainly LTB4 and IL-8. The inhibition of one of these mediators (IL-5, IL-8 or LTB4) completely blocked the eosinophil migration induced by saline, suggesting that they act synergistically.

Differential correlation between interleukin patterns in disseminated and chronic human paracoccidioidomycosis

In an attempt to understand better the immunoregulatory disorders in paracoccidioidomycosis (PCM), the possible correlation between interleukin pattern, lymphoproliferation, C-reactive protein (CRP) and specific antibody levels was investigated in the polarized clinical forms of this disease. We studied 16 PCM patients, eight with the disseminated disease (four under treatment and four non-treated) and eight with the chronic disease. The patients with disseminated disease exhibited high antibody titres specific to Paracoccidioides brasiliensis antigen compared with patients with the chronic form of disease. Tumour necrosis factor (TNF), IL-1, IL-6 and CRP in the serum of non-treated disseminated PCM patients were increased, which correlated positively with the low mitogenic response of peripheral blood mononuclear cells (PBMC) to phytohaemagglutinin (PHA) (P < 0.01) and with the high antibody titres (P < 0.001) of these patients. Moreover, we found in the disseminated PCM patients positive correlations between IL-1 and IL-6 (P = 0.0007); IL-1 and TNF (P = 0.0045); IL-1 and IL-6 with the high antibody titres (P = 0.0834 and P = 0.0631, respectively); IL-1, IL-6 and TNF with CRP levels. By contrast, no correlations were found with those interleukins in the treated disseminated and chronic patients or in controls. It was interesting to find an inverse correlation between IL-4 and antibody production in non-treated disseminated PCM (r = -0.4770); moreover, a significant correlation (P = 0.0820) was found in chronic PCM patients with respect to the low level of either IL-4 and antibody titres against fungus antigen. Chronic PCM patients also had IL-2 levels inversely correlated with antibody production (r = -0.6313; P = 0.0628). Inverse correlations were also observed between IL-2 and IL-6 levels in non-treated disseminated patients (P = 0.0501) and between IL-2 and IL-4 in chronic patients (P = 0.0131). The inflammatory cytokines might have a pivotal role in the genesis and in control of some aspects of the disease, such as granulomatous reaction, hypergammaglobulinaemia and depression of T cell-mediated immunity in PCM.

LPS-induced 111In-eosinophil accumulation in guinea-pig skin: evidence for a role for TNF-alpha

Lipopolysaccharide (LPS) is a major component of the cell wall of Gram-negative bacteria with powerful pro-inflammatory activities. Although the mechanisms involved in LPS-induced neutrophil accumulation have been studied extensively, few reports have focused on the effects of LPS on eosinophil infiltration. In this study we have used an in vivo model of local 111In-eosinophil accumulation in the guinea-pig to investigate the mechanisms of LPS-induced eosinophilia. Using a 4-hr in vivo test period, the intradermal injection of LPS (50-1000 ng/site) led to a marked and dose-dependent accumulation of 111In-eosinophils into guinea-pig skin sites. Time-course experiments revealed that this cell infiltration was delayed in onset, becoming significant 1 hr after the intradermal administration of LPS. The slow development of the response and its sensitivity to the locally administered protein synthesis inhibitor, actinomycin D, suggested that the LPS-induced 111In-eosinophil accumulation in vivo is mediated by the generation of de novo proteins. The intravenous pretreatment of guinea-pigs with a soluble tumour necrosis factor-alpha (TNF-alpha) receptor fusion protein (TNFR-IgG, 1 mg/kg), potently inhibited the 111In-eosinophil accumulation induced by LPS. Our results demonstrate that LPS can induce 111In-eosinophil accumulation in vivo in guinea-pig skin, and that this process is mediated by TNF-alpha.

Investigation of the endogenous chemoattractants involved in 111In-eosinophil accumulation in passive cutaneous anaphylactic reactions in the guinea-pig

1. Eosinophil accumulation and plasma extravasation are features of type I allergic responses. In an attempt to characterize the mediators of these responses, we have examined the local accumulation of 111In-eosinophils and leakage of 125I-human serum albumin (125I-HSA) during passive cutaneous anaphylaxis (PCA) reactions and in response to defined inflammatory mediators in the guinea-pig. Animals were passively sensitized by intradermal injection of anti-bovine gamma globulin antibody (50 microliters, 1/50 dilution). After 20-24 h, animals were injected intravenously with 111In-eosinophils and 125I-HSA for the measurement of cell accumulation and plasma leakage, respectively. 2. When injected into sensitized sites, antigen caused a dose-related increase in the accumulation of 111In-eosinophils and plasma leakage in guinea-pig skin. Time course experiments over 24 h revealed that the maximal rate of 111In-eosinophil accumulation occurred over the first 90 min, with little accumulation at later time points. Plasma leakage was completed within the first 30 min after challenge. Responses to the mast cell degranulator, compound 48/80, exhibited very similar responses to the PCA reaction. 3. Co-injection of antigen with the PAF antagonist, WEB 2086 (10(-7) mol/site) or the 5-lipoxygenase inhibitor, PF 5901 (10(-7) mol/site) did not significantly alter the accumulation of 111In-eosinophils or plasma leakage, whereas these drug doses abolished responses to exogenous PAF (10(-9) mol/site) and arachidonic acid (AA, 3 x 10(-8) mol/site), respectively. The H1 receptor antagonist chlorpheniramine (2.5 x 10(-8) mol/site) did not reduce antigen-induced 111In-eosinophil accumulation. Drug combinations were also injected with antigen into sensitized sites, but were unable to reduce "'In-eosinophil accumulation.4. These results indicate that anaphylactic eosinophil accumulation in this model involves mediators other than histamine, PAF or lipoxygenase products. This is in contrast to plasma leakage in this reaction, which can be abolished by a combination of antagonists blocking these mediators.

Role of resident peritoneal cells in eosinophil migration induced by saline

In the present study, we investigated the role of resident peritoneal cells as well as the mediators involved in the eosinophil migration induced by large volumes of physiological saline. Two consecutive intraperitoneal injections of saline given 48 h apart, induced a selective recruitment of eosinophils into the cavity. This response was not observed with phosphate-buffered saline (PBS). Saline-induced eosinophil migration may be mediated at least in part by LTB4, since the lipoxygenase inhibitors BW A4C and MK 886 prevented the response. In the presence of saline, but not of PBS, mast cells and macrophages incubated in vitro released a factor which induced eosinophil migration when injected into the peritoneal cavity of rats. This release was inhibited by BW A4C and MK 886. These results indicate the importance of mast cells and macrophages in the eosinophil migration induced by saline and suggest the participation of LTB4 in this phenomenon. An abrupt reduction in the extracellular potassium concentration at the membrane of resident cells may be responsible for the saline effects since addition of potassium ions to saline abolished the eosinophil chemotactic activity of the same as well as its ability to stimulate the release of eosinophil chemotactic factor in vitro. Dexamethasone blocked both the saline-induced eosinophil migration and the release of eosinophil chemotactic factor by mast cells and macrophages. Pretreatment of the animals with dexamethasone inhibited the eosinophil migration induced either by the supernatants of saline-stimulated mast cells and macrophages or by LTB4. These results indicate that the release of additional mediators is necessary in order to account for the final eosinophil migration.(ABSTRACT TRUNCATED AT 250 WORDS)

Eosinophil accumulation induced by human interleukin-8 in the guinea-pig in vivo

Interleukin-8 (IL-8) is a neutrophil chemoattractant cytokine. Initially IL-8 appeared to exhibit specificity for neutrophils over other cells of the immune system. However, several recent studies have shown that this mediator can also activate other leucocyte types in vitro. In this study we have used an in vivo model of local [111In]leucocyte accumulation in the guinea-pig and an in vitro assay of leucocyte activation (changes in cytosolic-free Ca2+) to investigate the eosinophil chemoattractant activity of IL-8. The intradermal injection of recombinant human (rh)IL-8 induced a dose-dependent accumulation of intravenously administered [111In]eosinophils into the skin sites over 4 hr. Time-course experiments revealed that this cell infiltration was delayed in onset, occurring between 1 and 2 hr after injection of IL-8. The delay may indicate that IL-8 operates via an indirect mechanism. In contrast, eosinophil accumulation induced by the complement fragment C5a occurred within the first hour following injection. Other human cytokines, IL-1, IL-3, IL-5, tumour necrosis factor (TNF) and granulocyte-macrophage colony-stimulating factor (GM-CSF), were not eosinophil chemoattractants in this in vivo test system. Direct activation of eosinophils by IL-8 was demonstrated in vitro by a transient elevation in cytoplasmic-free Ca2+ levels where it was less potent than either rhC5a or leukotriene B4 (LTB4). Experiments using [111In]neutrophils in vivo indicated that rhIL-8 and rhC5a were similar in potency in inducing local neutrophil infiltration into guinea-pig skin. The demonstration of the eosinophil chemoattractant activity of IL-8 in vivo raises the possibility that this cytokine, or a structurally related molecule, contributes towards eosinophil infiltration in a number of inflammatory conditions such as asthma, helminthic infections and adult respiratory distress syndrome.

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.

Blockade of hyperalgesia and neurogenic oedema by topical application of nitroglycerin

Surprisingly, a single topical application of a nitroglycerin (NTG) gel in humans has been shown to cause analgesia and to reduce oedema in thrombophlebitis. In the present investigation, we showed that the NTG gel reduces prostaglandin E2-induced hyperalgesia and blocks neurogenic inflammation induced in rat skin by antidromic electrical stimulation of the saphenous nerve. These results offer an explanation for the effects of topical application of NTG observed in thrombophlebitis, which may be common to other cutaneous pathologies. The data also support the development of nitrates the effects of which are restricted to the site of application.

The accumulation of 111In-eosinophils induced by inflammatory mediators, in vivo

Eosinophils are implicated in the pathogenesis of a variety of allergic inflammatory diseases such as asthma. Several substances have been shown to be chemotactic for eosinophils in vitro, but the inflammatory mediators involved in the accumulation of eosinophils in vivo are as yet unidentified. In this study we have developed a system to measure the accumulation of 111In-eosinophils in guinea-pig skin in vivo. Horse serum-induced guinea-pig peritoneal eosinophils were radiolabelled with 111In and injected intravenously into recipient animals. 125I-albumin was also injected intravenously in order to measure local oedema formation simultaneously. A range of putative mediators was injected intradermally and responses measured for up to 2 hr. Of the mediators tested, guinea-pig C5a des Arg in zymosan-activated plasma was the most active. Recombinant human C5a (rHC5a) was also highly active, but less than the guinea-pig material. C5a des Arg in maximally activated plasma induced a 1500% increase in eosinophil accumulation, while rHC5a (10(-10) mol dose) induced a 600% increase. Platelet-activating factor (PAF) and leukotriene B4 (LTB4) were also tested for comparison. With respect to 111In-eosinophil accumulation, the order of potency of the mediators tested was as follows: guinea-pig C5a des Arg greater than LTB4 greater than PAF. In contrast, the order of potency of the mediators with respect to oedema formation was: PAF greater than guinea-pig C5a des Arg greater than LTB4. The techniques described will facilitate analysis of the mechanisms involved in eosinophil accumulation in defined inflammatory reactions.

Recombinant interleukin-1 and tumor necrosis factor induce neutrophil migration "in vivo" by indirect mechanisms

The alpha and beta forms of recombinant interleukin-1 (IL-1 alpha and IL-1 beta) and of recombinant Tumor Necrosis Factor (TNF alpha and TNF beta) induced dose-dependent neutrophil migration into rat peritoneal cavities. Migration induced by both IL-1s showed a bell-shaped dose-response curve and IL-1 beta was 3-fold more potent than IL-1 alpha. Pretreatment of the animals with dexamethasone or depletion of the peritoneal macrophage population, abolished the neutrophil migration induced by the four cytokines. "In vitro" stimulation of macrophage monolayers with IL-1 beta and the TNFs released a factor into the supernatant which, unlike these cytokines, induced neutrophil migration in dexamethasone pretreated animals. These results suggest that the neutrophil migration induced by IL-1 alpha, IL-1 beta, TNF alpha and TNF beta is not due to a direct effect on neutrophils, but occurs via the release of a chemotactic factor(s) from resident macrophages.

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.

The anti-oedematogenic effect of SRS as an additional factor in the mode of action of non-steroid anti-inflammatory drugs

A partially purified preparation of SRS was obtained from peritoneal exudates induced by a non-anaphylactic immediate hypersensitivity reaction. This preparation injected in the rat skin caused vasoconstriction and when administered together with carrageenin reduced oedema formation. Injection of carrageenin into the peritoneal cavity progressively increased exudate formation. Pretreatment of the animals with anti-inflammatory doses of aspirin, indomethacin and salicylate significantly reduced exudate formation and this inhibition was correlated with the appearance of SRS in the exudates. It is suggested that, in some inflammatory exudates, stimulation of the synthesis of vasoconstrictor SRS might be an additional factor to the inhibition of prostaglandin synthesis induced by non-steroid anti-inflammatory drugs.