Tumor necrosis factor in leprosy patients

Do leprosy and tuberculosis generate a systemic inflammatory shift? Setting the ground for a new dialogue between experimental immunology and bioarchaeology

It is possible that during long lasting chronic infections such as tuberculosis (TB) and leprosy individuals who generate a stronger immune response will produce a chronic shift in the systemic levels of inflammatory proteins. Consequently, the systemic immunological shift could affect inflammatory responses against other persistent pathogens such as Porphyromonas gingivalis associated with periodontal disease (PD).

OBJECTIVE

To determine if in vitro exposure to Mycobacterium tuberculosis or M. leprae lysates impacts subsequent immune responses to P. gingivalis; and to propose a new dialogue between experimental immunology and paleopathology.

MATERIAL AND METHODS

We sequentially (2 days protocol) exposed peripheral blood mononuclear cells (PBMCs) from healthy donors to bacterial lysates either from M. tuberculosis, or M. leprae, or P. gingivalis. After collecting all supernatants, we measured the expression of immune proteins TNFα and IFNγ using an enzyme-linked immunosorbent assay.

RESULTS

Early exposure (day 1) of PBMCs to M. leprae or M. tuberculosis lysates induces an inflammatory shift detected by the increase of TNFα and IFNγ when the same cells are subsequently (day 2) exposed to oral pathogen P. gingivalis.

DISCUSSION

By extrapolating these results, we suggest that chronic infections, such as TB and leprosy, could generate a systemic immunological shift that can affect other inflammatory processes such the one present in PD. We propose that the presence and severity of PD should be explored as a proxy for inflammatory status or competence when reconstructing the health profile in past populations.

Relationship between growth factors and its implication in the pathogenesis of leprosy

Leprosy is a chronic infectious disease caused by Mycobacterium leprae which affects the skin and peripheral nervous system. The immune response of the host determines the clinical course of the disease. The tuberculoid form is the result of high cell-mediated immunity characterized by a Th1 response, whereas the lepromatous form is characterized by low cell-mediated immunity and a Th2 humoral response. The neural damage established produces marked changes in the expression of growth factors such as nerve growth factor (NGF) and its receptors (NGF-R). The expression of NGF, associated with the expression of Th1 and Th2 cytokines, might be involved in the tissue damage caused by the bacillus. Therefore, the objective of this study was to correlate the immunoexpression patterns of NGF and NGF-R in the different clinical forms of leprosy, and to associate the findings with the in situ expression of TGF-β and clinical classification of the disease. TGF-β, NGF and NGF-R immunoexpression was analyzed by immunohistochemistry in paraffin-embedded material. Most patients were males with a mean age of 40.7 years. TGF-β levels were significantly higher in the lepromatous forms. No significant difference in the immunoexpression of NGF or NGF-R was observed between the clinical forms, but expression tended to be higher at the lepromatous pole. There was a significant positive correlation between NGF and NGF-R in the different clinical forms of leprosy. A significant positive correlation was observed between NGF, NGF-R and TGF-β. It can be concluded that, even existing evidence on the role of these molecules in the clinical spectrum of leprosy.

Leprosy: review of the epidemiological, clinical, and etiopathogenic aspects - part 1

Leprosy is caused by Mycobacterium leprae and has been known since biblical times. It is still endemic in many regions of the world and a public health problem in Brazil. The prevalence rate in 2011 reached 1.54 cases per 10,000 inhabitants in Brazil. The mechanism of transmission of leprosy consists of prolonged close contact between susceptible and genetically predisposed individuals and untreated multibacillary patients. Transmission occurs through inhalation of bacilli present in upper airway secretion. The nasal mucosa is the main entry or exit route of M. leprae. The deeper understanding of the structural and biological characteristics of M. leprae, the sequencing of its genome, along with the advances in understanding the mechanisms of host immune response against the bacilli, dependent on genetic susceptibility, have contributed to the understanding of the pathogenesis, variations in the clinical characteristics, and progression of the disease. This article aims to update dermatologist on epidemiological, clinical, and etiopathogenic leprosy aspects.

Serial measurement of the circulating levels of tumour necrosis factor and its soluble receptors 1 and 2 for monitoring leprosy patients during multidrug treatment

Leprosy is an infectious and contagious spectral disease accompanied by a series of immunological events triggered by the host response to the aetiologic agent, Mycobacterium leprae . The induction and maintenance of the immune/inflammatory response in leprosy are linked to multiple cell interactions and soluble factors, primarily through the action of cytokines. The purpose of the present study was to evaluate the serum levels of tumour necrosis factor (TNF)-α and its soluble receptors (sTNF-R1 and sTNF-R2) in leprosy patients at different stages of multidrug treatment (MDT) in comparison with non-infected individuals and to determine their role as putative biomarkers of the severity of leprosy or the treatment response. ELISA was used to measure the levels of these molecules in 30 healthy controls and 37 leprosy patients at the time of diagnosis and during and after MDT. Our results showed increases in the serum levels of TNF-α and sTNF-R2 in infected individuals in comparison with controls. The levels of TNF-α, but not sTNF-R2, decreased with treatment. The current results corroborate previous reports of elevated serum levels of TNF-α in leprosy and suggest a role for sTNF-R2 in the control of this cytokine during MDT.

Leprosy as a model of immunity

ABSTRACT: Leprosy displays a spectrum of clinical manifestations, such as lepromatous and tuberculoid leprosy, and type I and II lepra reactions, which are thought to be a reflection of the host’s immunological response against Mycobacterium leprae. Therefore, differential recognition of M. leprae, as well as its degraded components, and subsequent activation of cellular immunity will be an important factor for the clinical manifestation of leprosy. Although M. leprae mainly parasitizes tissue macrophages in the dermis and the Schwann cells of peripheral nerves, the presence of M. leprae in other organs, such as the liver, may also play important roles in the further modification of seesaw-like bipolar phenotypes of leprosy. Thus, leprosy is an exciting model for investigating the role of the human immune system in host defense and susceptibility to infection.

Clinical and immunological evaluation after BCG-id vaccine in leprosy patients in a 5-year follow-up study

INTRODUCTION

The use of bacillus Calmette-Guérin (BCG) has long been considered a stimulus for immune reactivity in leprosy household contacts. Probably, the combination of multidrug therapy with BCG could facilitate the clearance of leprosy bacilli in the host, reduce relapse rates, and shorten the duration of skin-smear positivity.

METHODS

To investigate the mechanism of action of BCG, a study involving 19 leprosy patients, eleven multibacillary (MB) and eight paucibacillary, was performed to assess the in vitro production of interleukin (IL)-10, interferon (IFN)-γ, tumor necrosis factor (TNF)-α, IL-6, and IL-17 in the supernatant of peripheral blood mononuclear cells, before and 30 days after inoculation with BCG intradermally (BCG-id). Peripheral blood mononuclear cells isolated by Ficoll-Hypaque gradient were cultivated with Concanavalin-A (Con-A), lipopolysccharides (LPS), or BCG. The supernatant was collected for ELISA quantification of cytokines. The immunohistochemistry of IFN-γ, IL-1, IL-10, IL-12, transforming growth factor (TGF)-β, and TNF-α was carried out in biopsies of skin lesions of leprosy patients before and 30 days after inoculation of BCG-id. These patients were followed up for 5 years to assess the therapeutic response to multidrug therapy, the occurrence of leprosy reactions, and the results of bacterial index and anti-PGL-1 serology after the end of treatment.

RESULTS

The results showed increased production of cytokines after BCG-id administration in MB and paucibacillary leprosy patients. There was statistically higher levels of TNF-α (P = 0.017) in MB patients and of IL-17 (P = 0.008) and IFN-γ (P = 0.037) in paucibacillary patients. Immunohistochemical staining, especially for TNF-α, was more intense in biopsies of MB leprosy patients taken after BCG-id administration, probably for induction of innate human immunity. The clinical evaluation suggests that BCG-id is able to induce a more effective therapeutic response, with reduction of the number and the intensity of leprosy reactions.

CONCLUSION

These results suggest that BCG-id induces activation of the initial phase of immunocellular activity: innate human immunity (increase in TNF-α, IL-12 and macrophage activation). Therefore, we conclude that the use of BCG-id could be indicated as an adjuvant to multidrug therapy in treatment of leprosy patients.

Evaluation of the expression of interleukin 1 beta (IL-1beta) and interleukin 1 receptor antagonist (IL-1Ra) in leprosy patients

Leprosy is an infectious and contagious spectral disease accompanied by a series of immunological events triggered by the host's response to the etiologic agent, Mycobacterium leprae. Evidence suggests that the induction and maintenance of the immune/inflammatory response in leprosy are linked to multiple cell interactions and soluble factors, mainly through the action of cytokines. The ELISA test was used to measure the levels of IL-1beta and IL-1Ra in 37 new leprosy patients followed-up during treatment and 30 healthy controls. Peripheral blood was collected four times during the treatment of leprosy patients (MDT pretreatment, 2nd dose, 6th dose and post-MDT), and only once from the controls. The comparison of molecular levels in pre-MDT patients and controls showed a statistically significant difference for IL-1beta. The results suggest the participation of this cytokine in the genesis of the immune/inflammatory process.

Influence of TNF and IL10 gene polymorphisms in the immunopathogenesis of leprosy in the south of Brazil

OBJECTIVE

To determine whether cytokine polymorphisms are associated with leprosy and/or their subtypes in a Brazilian population.

METHODS

Genotyping using polymerase chain reaction with sequence-specific primers (PCR-SSP) was performed for: TNF(-308/-238), IL2(-330/+166), IL6(-174), IFNG(+874), TGFB1(+869/+915), and IL10(-592/-819/-1082) in 240 healthy controls and 167 patients with leprosy.

RESULTS

For TNF(-308), a higher frequency of GG genotype (85.5% vs. 74.1% in healthy controls, p = 0.009), along with a decreased frequency of GA/AA genotypes was observed among leprosy patients as compared to the control group (14.5% vs. 25.9%, p = 0.009). The GG genotype was particularly higher in patients with tuberculoid (TT) and borderline (BB) leprosy (90.5% and 89.8%, respectively). Analysis of IL10 genotypes revealed a lower frequency of GCC/GCC haplotype in lepromatous leprosy (LL) patients (6.2%) in comparison to controls (15.4%).

CONCLUSION

It is suggested that the G-->A substitution at position -308 in the TNF promoter region plays an important role in leprosy patients.

HLA-DRB1*12 is associated with protection against complicated typhoid fever, independent of tumour necrosis factor alpha

We investigated whether HLA-DR2 or -DR12 alleles in 63 Javanese patients with complicated or non-complicated typhoid fever were associated with severity of disease. No association was observed between HLA type and susceptibility to disease. However, in patients we did find a negative association of DR12 (DRB1*12021) with complicated typhoid fever (P = 0.05; OR = 0.3; 95% CI: 0.1-1.0). No effect of DR2 (DRB1*1502) on outcome (P = 0.46; OR = 1.5; 95% CI: 0.5-4.5) was demonstrated. The odds ratio for DR12 remained unchanged after adjusting for DR2. Tumour necrosis factor alpha (TNF-alpha) production capacity in lipopolysaccharide (LPS)-stimulated whole blood culture, as measured by non-equilibrium radioimmunoassay, was significantly lower in complicated than in non-complicated cases (P = 0.02), confirming previous data. No significant correlation of either DR12 (P = 0.47) or DR2 (P = 0.89) was found with TNF-alpha production capacity. Apparently, protection against complications by DR12 is attributable to other mechanisms.

[Immunopathology of leprosy: the complexity of the mechanisms of host immune response to Mycobacterium leprae]

Leprosy, whose etiologic agent Mycobacterium leprae, is an illness of ample clinical and immunopathological spectrum. Its clinical manifestations are correlated with distinct immunologic forms, varying from a vigorous immune response mediated by cells to M. leprae, with Th1 standard in the tuberculoid polar region, to an absence of specific cellular response to antigens of M. leprae in the lepromatous polar region, with predominance of Th2 response and exacerbation of humoral response. It is probable that different polymorphic genes determine susceptibility to M. leprae. Additional studies are necessary to clarify the complex interactions between cytokines and the role of the phenotypic diversity of cells network that contribute to the host defense. The comprehension of such mechanisms will provide new insights for the identification of agonists and/or antagonists for pro- or anti-inflammatory effects, and also will indicate possible situations for its appropriate use in immunologic and/or immunotherapeutic interventions.

[Edema in leprosy: the clinical and therapeutic aspects]

Edema, which is commonly described as a symptom of reactional states, may occur during the course of leprosy. Both diagnosis and adequate treatment measures are often difficult to achieve and failure to do so may result in permanent damage to the lower limbs. In a one-year follow-up study of leprosy patients--ten multibacillary and one paucibacillary--who had been submitted to a clinical protocol for diagnosis and pathological classification, a clinical pattern of localized and/or systemic edema was observed. Among these patients, five simultaneously presented other symptoms related to reactional states, 4 were diagnosed as Type I, and one as Type II. On the other hand, while three of the patients did not present reaction at the time when edema was diagnosed, they did develop some aspects of reactional disease later on (two had neuritis e one had Type I reaction). The edemas that preceded or were associated with reactional episodes showed clinical regression as a result of specific treatment against reactions (corticosteroids and/or pentoxifylline and/or thalidomide) in the absence of another treatment normally used for edemas. Although these data need to be confirmed by controlled studies, they strongly suggest that immunological mechanisms are involved in the physiopathology of edema in leprosy.

Cytokines in leprosy, I. Serum cytokine profile in leprosy

BACKGROUND

Leprosy is a chronic infectious disease characterized by a broad spectrum of clinical forms depending on the patient's immune response, in particular cell-mediated immune response.

METHODS

Cytokines can play a role in the cell-mediated immune response. Serum levels of interferon-gamma (IFN-gamma), interleukin-2 (IL-2), interleukin-2 receptor (IL-2R), interleukin-10 (IL-10), tumor necrosis factor-alpha (TNF-alpha), and interleukin-1beta (IL-1beta) were measured by enzyme-linked immunosorbent assay (ELISA) in 55 untreated leprosy patients and 35 reactional leprosy patients, in addition to 20 age- and sex-matched healthy controls.

RESULTS

Leprosy patients showed significantly higher serum levels of the studied cytokines (except IL-2) compared with healthy controls. When the two poles were compared, tuberculoid leprosy (TT) patients showed significantly higher levels of IFN-gamma and TNF-alpha with significant negative correlations with the bacterial index (BI), whereas lepromatous leprosy (LL) patients showed significantly higher serum levels of IL-2R, IL-10, and IL-1beta with significant positive correlations with the BI. Both type I and type II reactional patients showed significantly higher serum IFN-gamma, IL-2R, and IL-1beta, in addition to IL-10 in type II reactional patients, compared with nonreactional leprosy patients. When compared with each other, type I reactional patients showed increased levels of IFN-gamma, whereas type II reactional patients showed increased levels of IL-10.

CONCLUSIONS

In leprosy patients, both IFN-gamma and TNF-alpha are immunoprotective, whereas IL-2R, IL-10, and IL-1beta are immunosuppressive. Our results indicate that type I reaction, with increased levels of IFN-gamma, is a cell-mediated immune response, whereas type II reaction, with increased levels of IL-10, is essentially an immune complex disease.

Immunological status of ENL (erythema nodosum leprosum) patients: its relationship to bacterial load and levels of circulating IL-2R

Recent data suggest that the clinical course of reactional states in leprosy is closely related to the cytokine profile released locally or systemically by the patients. In the present study, patients with erythema nodosum leprosum (ENL) were grouped according to the intensity of their clinical symptoms. Clinical and immunological aspects of ENL and the impact of these parameters on bacterial load were assessed in conjunction with patients' in vitro immune response to mycobacterial antigens. In 10 out of the 17 patients tested, BI (bacterial index) was reduced by at least 1 log from leprosy diagnosis to the onset of their first reactional episode (ENL), as compared to an expected 0.3 log reduction in the unreactional group for the same MDT (multidrug therapy) period. However, no difference in the rate of BI reduction was noted at the end of MDT among ENL and unreactional lepromatous patients. Accordingly, although TNF-alpha (tumor necrosis factor) levels were enhanced in the sera of 70.6% of the ENL patients tested, no relationship was noted between circulating TNF-alpha levels and the decrease in BI detected at the onset of the reactional episode. Evaluation of bacterial viability of M. leprae isolated from the reactional lesions showed no growth in the mouse footpads. Only 20% of the patients demonstrated specific immune response to M. leprae during ENL. Moreover, high levels of soluble IL-2R (interleukin-2 receptor) were present in 78% of the patients. Circulating anti-neural (anti-ceramide and anti-galactocerebroside antibodies) and anti-mycobacterial antibodies were detected in ENL patients' sera as well, which were not related to the clinical course of disease. Our data suggest that bacterial killing is enhanced during reactions. Emergence of specific immune response to M. leprae and the effective role of TNF-alpha in mediating fragmentation of bacteria still need to be clarified.

Elaboration of type-1 plasminogen activator inhibitor from adipocytes. A potential pathogenetic link between obesity and cardiovascular disease

BACKGROUND

Obesity is known to predispose to attenuated fibrinolysis attributable to increased concentrations in plasma of type-1 plasminogen activator inhibitor (PAI-1), the primary physiological inhibitor of endogenous fibrinolysis. PAI-1 is present in neointimal vascular smooth muscle cells and lipid-laden macrophages.

METHODS AND RESULTS

The present study was designed to determine whether PAI-1 expression occurs in adipose tissue as well, thereby potentially contributing to increased cardiovascular risk associated with obesity. 3T3-L1 preadipocytes were differentiated into adipocytes by exposing them to isobutylxanthine (0.5 mmol/L) and dexamethasone (0.25 mumol/L) over 7 days and incubated for 24 hours with transforming growth factor-beta (TGF-beta), known to augment PAI-1 synthesis in several cell types and to be released from platelets when they are activated. TGF-beta increased PAI-1 activity in the conditioned media of the 3T3-L1-derived cells in a concentration-dependent fashion without significantly affecting cell proliferation. Western blotting and immunoprecipitation of 35S-labeled PAI-1 showed that the increased PAI-1 activity paralleled increased PAI-1 protein. Northern blotting showed that increased PAI-1 mRNA preceded increased accumulation of PAI-1 activity and protein in the conditioned media. Furthermore, TGF-beta (10 ng/g body wt) administered in vivo increased PAI-1 activity in mouse plasma and PAI-1 mRNA expression in mouse adipose tissue.

CONCLUSIONS

Increased plasma PAI-1 activity in obese human subjects may result from PAI-1 release from an increased mass of adipose tissue, particularly in association with thrombosis and elaboration of TGF-beta from platelet alpha-granules into the circulation. The increased PAI-1 may exacerbate vascular disease by shifting the balance between thrombosis and thrombolysis toward thrombosis and consequently exposing luminal surfaces of vessels to mitogens associated with microthrombi over protracted intervals.

Regulation of murine macrophage effector functions by lipoarabinomannan from mycobacterial strains with different degrees of virulence

Lipoarabinomannan (LAM) is the major arabinose- and mannose-containing phosphorylated lipopolysaccharide (LPS) in mycobacterial cell walls. LAM preparations from a virulent strain (Erdman) (LAM(Erdman)) and an attenuated strain (H37Ra) (LAMH37Ra) of Mycobacterium tuberculosis, as well as from M. leprae (a virulent mycobacterium), were analyzed for their effects on various macrophage (M phi) effector functions. LAMH37Ra, like gram-negative LPS, exhibited a dose-dependent ability to induce tumor necrosis factor alpha (TNF-alpha) production in normal M phi, and gamma interferon (IFN-gamma) priming of the M phi greatly augmented the levels of TNF-alpha. However, the effects of LAMH37Ra were unaffected by polymyxin B, which totally abrogated the effects of LPS. LAM(Erdman) and LAM from M. leprae, on the other hand, induced virtually no TNF-alpha production. Analysis of M phi mRNA by reverse transcription-polymerase chain reaction revealed that the levels of production. Analysis of M phi mRNA by reverse transcription-polymerase chain reaction revealed that the levels of TNF-alpha mRNA induced by the various preparations correlated with the levels of TNF-alpha protein detected. Interestingly, both LAMH37Ra and LAM(Erdman) could block subsequent IFN-gamma- and LPS-induced M phi activation, a previously reported measure of the potent ability of LAM to down-regulate M phi effector functions. Two lines of evidence suggested, however, that M phi cyclooxygenase products did not play a role in this down-regulation. LAMH37Ra and LPS could induce the production of NO2- in both normal and IFN-gamma-primed M phi, whereas LAM(Erdman) could stimulate NO2- production only in primed M phi. Both LAMH37Ra and LAM(Erdman) could substitute for LPS as a triggering signal for IFN-gamma-primed M phi in a toxoplasma killing assay. The triggering ability of LAM(Erdman), however, was abrogated by an anti-TNF-alpha antibody, suggesting that sufficient TNF-alpha production was stimulated by LAM(Erdman) to drive a M phi function relevant in host resistance. Thus, mycobacterial LAM is a potent regulator of M phi functions, a fact that may have important consequences in mycobacterial disease.

Tumour necrosis factor production in vivo and in vitro in response to Paracoccidioides brasiliensis and the cell wall fractions thereof

Tumour necrosis factor (TNF) was detected in serum from mice challenged with Paracoccidioides brasiliensis. The serum TNF levels of mice challenged with an avirulent strain were significantly higher than those of mice challenged with a virulent strain, and the same was observed for the TNF levels of mice challenged with a cell wall fraction (F1) from the two fungal strains. Fraction F1 consisted of chitin and beta-glucan; but although the chitin contents were similar for the two strains, the avirulent strain allowed a greater content of beta-glucan. The beta-glucan, purified from both strains, increased serum TNF levels in an identical dose-dependent manner, whereas purified chitin did not induce serum TNF levels. P. brasiliensis, the F1 fractions and beta-glucan induced macrophages to secrete TNF in vitro. The differences in TNF levels, induced by the different fungal strains, were correlated with the beta-glucan concentrations in the cell walls of both the avirulent and virulent strains of P. brasiliensis. These findings support a role for TNF in the pathogenicity of P. brasiliensis.

Tumor necrosis factor: status in reactions in leprosy before and after treatment

BACKGROUND

Tumor necrosis factor-alpha (TNF) is an important mediator of immunologic responses to chronic infections.

METHOD

Sera from 25 patients with acute reactions (6 with type 1 upgrading, 8 with type 1 downgrading, and 11 with type 2 reaction) were assayed for TNF before treatment and after clinical remission of the acute episode. The results were compared with serum TNF levels in healthy controls and fresh pauci- and multibacillary leprosy patients.

RESULTS

TNF levels in acute reactions were higher than in the control groups (significant only in upgrading reaction). In type 1 reaction, serum TNF concentrations fell to approximately the levels of the control patients following treatment and clinical remission. In type 2 reaction, however, levels of TNF were seen to rise further (became statistically significant) as a result of therapy induced clinical remission.

CONCLUSIONS

The rise in TNF-alpha level in reactions in leprosy is significant and indicates its active role in immunopathogenesis. The corresponding decline in TNF-alpha levels seen following regression of type 1 (lepra) reactions was not observed in the case of type 2 (ENL) reaction. This probably reflects the enhancement of cellular immunity in such cases and/or an attempt by the immunologic process to overcome specific inhibitors.

Suppression of cytokine production by supernatants from CD8+ lymphocytes activated by mycobacterial fractions: the role of interleukins 4 and 6

Supernatants derived from CD8+ lymphocytes treated with mycobacterial components, or the partially purified carbohydrates from these supernatants, increased the production of IL-4 and IL-6 by mononuclear cells. The addition of anti-IL4 or anti-IL6 antibodies to LPS stimulated MN cells incubated with supernatants from CD8+ lymphocytes or carbohydrates resulted in the restoration of other cytokine production by these MN cells. Recombinant IL-4 and IL-6 on their own suppressed the production of IL-1 beta, TNF-alpha, IL-2 and IFN-gamma by mononuclear cells. Such suppression could be reversed with antibodies to IL-4 and IL-6. The addition of rIL-4 and rIL-6 did not increase the suppression of cytokine production induced by suppressor supernatants or carbohydrates. Interleukin 4 decreased the production of IL-6 by MN cells; whilst IL-6 suppressed IL-4 production in a dose dependent manner. Both effects could be reversed with the appropriate antisera. Our results suggest that mycobacteria could evade host immunity by inducing the production of IL-4 and IL-6 by host mononuclear cells. These cytokines, in turn, would suppress the production of other cytokines necessary for effective cellular immunity.

Effects of clofazimine analogues and tumor necrosis factor-alpha individually and in combination on human polymorphonuclear leukocyte functions in vitro

In the present study the individual and interactive effects of clofazimine, or three analogues of this agent (selected on the basis of similar or superior pro-oxidative properties: B669, B746 and B4021) and human recombinant TNF-alpha on the generation of antimicrobial oxidants by human polymorphonuclear leukocytes (PMNL), as well as release of granule enzymes from these cells, were investigated in vitro. All four riminophenazines at the concentrations tested (0.5 and 1.0 micrograms/ml) significantly increased myeloperoxidase (MPO)-mediated iodination, superoxide (0(2).-) generation, oxygen (0(2)) consumption and chemiluminescence (CL), as well as the release of both primary and secondary granule contents (measured as the release of MPO, lysozyme and vitamin B12-binding protein) by stimulated PMNL. Similar, but less impressive effects were observed with TNF-alpha (0.4-50.0 ng/ml). When PMNL were preincubated with both TNF-alpha and clofazimine or its analogues, the observed stimulation of cellular oxidative metabolism and granule enzyme release was at least additive in many assays. These data demonstrate that the spectrum of effects of clofazimine and its analogues on PMNL closely resemble those of TNF-alpha. Furthermore, TNF-alpha potentiates the pro-oxidative effects of clofazimine and its analogues on PMNL. Among the riminophenazines tested, clofazimine and B669 appear to be the most potent pro-oxidative agents for PMNL.

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.

Tumor necrosis factor production in patients with leprosy

The spectrum of host responses to Mycobacterium leprae provides a model for investigating the role of cytokines in the pathogenesis of mycobacterial disease. Of particular interest is tumor necrosis factor (TNF), a cytokine which may have both antimycobacterial and immunopathologic effects. To evaluate the potential role of TNF in leprosy, we measured TNF production in response to M. leprae and its defined constituents by peripheral blood mononuclear cells from patients across the spectrum of disease. The levels of TNF induced through the stimulation of cells with M. leprae or its dominant "lipopolysaccharide," lipoarabinomannan, were higher in patients with the tuberculoid form of the disease than in those with the lepromatous form. In patients with erythema nodosum leprosum (ENL), a reactional state of lepromatous leprosy, the levels of TNF release by peripheral blood mononuclear cells were higher than in any other form of the disease. Treatment of ENL patients with thalidomide reduced TNF secretion by more than 90%. The mycolylarabinogalactan-peptidoglycan complex of Mycobacterium species, the protein-peptidoglycan complex, and muramyl dipeptide all elicited significant TNF release. Therefore, TNF release appears to be triggered by at least two major cell wall structural constituents of M. leprae, lipoarabinomannan and segments of the cell wall skeleton. The prominent TNF release in patients with the paucibacillary tuberculoid form of the disease compared with that in patients with the multibacillary lepromatous form suggests that this cytokine contributes to a resistant immune response to mycobacterial infection. However, the marked TNF release in patients with ENL indicates that TNF may also mediate immunopathologic effects, such as fever and tissue damage.

Tumor necrosis factor-induced reversal of adipocytic phenotype of 3T3-L1 cells is preceded by a loss of nuclear CCAAT/enhancer binding protein (C/EBP)

Tumor necrosis factor (TNF)-treated 3T3-L1 adipocytes were used as a model for studying the effects of systemic inflammation on adipose tissue. Lipopolysaccharide-treated monocyte-conditioned medium or recombinant human TNF alpha induced morphological dedifferentiation of the adipocytes and led to loss of adipocyte specific gene expression. Gel shift, Southwestern and Western immunoblot analysis demonstrated that dedifferentiation was preceded by a decrease in the DNA binding activity and protein level of the transcription factor CCAAT/enhancer binding protein (C/EBP). Liver activating protein, a related protein that binds identical DNA sequences, increased during cytokine treatment. Both proteins activate specific enhancer elements located in the promoter region of many genes whose transcription is altered during systemic inflammation. Pulse-chase labeling followed by immunoprecipitation demonstrated that C/EBP is a rapidly turning over protein in adipocytes and that cytokine treatment led to a specific, time dependent decrease in its rate of synthesis. Because C/EBP binding sites have been shown to play an important role in regulating the expression of genes involved in adipocyte metabolism, we propose that the TNF-induced changes in the complement of transcription factors binding those sites may be important in the pathogenesis of inflammation-induced atrophy of adipose tissue.

TNF-alpha failed to reverse the M. leprae-induced defective chemiluminescence response of human mononuclear cells

The effect of phagocyte activation by TNF-alpha on the ability to trigger a chemiluminescence (CL) response, associated with the release of oxidizing species was evaluated in healthy human mononuclear cells in the presence of Mycobacterium leprae. Recombinant TNF-alpha (r-TNF-alpha) increased the CL response of unstimulated M. bovis BCG- and PMA-stimulated cells but did not reverse the M. leprae defective activation of the human phagocyte oxidative burst. M. leprae was less well phagocytosed than M. bovis BCG but phagocytosis of mycobacteria was not altered by addition of r-TNF-alpha. The failure of activation of oxygen-free radical production might have some relevance to the pathogenesis of leprosy.

Misoprostol but not antacid prevents endotoxin-induced gastric mucosal injury: role of tumor necrosis factor-alpha

Many of the complications of septic shock are believed to be a consequence of elevated circulating levels of tumor necrosis factor (TNF), which is an important mediator of tissue injury. Prostaglandins (PGs) of the E series have recently been reported to inhibit TNF production in vitro. We investigated the in vivo effect of misoprostol, a PGE1 analog, on endotoxin-induced gastric mucosal injury and TNF production. For the gastric mucosal injury studies, groups of animals were pretreated with intragastric misoprostol (100 and 200 micrograms/kg) or with antacid (2 ml/animal of Maalox Plus) 30 min prior to a challenge with intravenous E. coli lipopolysaccharide (LPS) at 5.0 mg/kg. Stomachs were examined 3 hr after LPS. Systemic endotoxin alone induced microscopic edema, vascular congestion, and polymorphonuclear (PMN) infiltration of the gastric mucosa. Pretreatment with misoprostol, but not with antacid, significantly and dose-dependently reduced the gastric mucosal injury. For the TNF studies, groups of rats were given either misoprostol (100 or 200 micrograms/kg, intragastric), or saline 1 hr prior to LPS challenge. Serum samples were obtained 1.5 hr after LPS challenge. Misoprostol dose-dependently and significantly (P less than 0.01) inhibited TNF activity. We conclude that misoprostol is a potent inhibitor of TNF systemic production and inhibits the gastric mucosal injury induced by endotoxemia. These studies suggest a potentially important therapeutic role for misoprostol in inflammatory diseases in which TNF exerts a contributory role.

Tumor necrosis factor levels in serum and bronchoalveolar lavage fluid of patients with the adult respiratory distress syndrome

Tumor necrosis factor (TNF) was measured antigenically and functionally in serum and bronchoalveolar lavage fluid (BAL) of patients with ARDS and those at high risk for ARDS. Of 22 patients with ARDS, 14 had sepsis or serious infection as the major clinical predisposition, and 10 of 20 high-risk patients had sepsis or serious infection. Mean levels of TNF in serum of patients with ARDS and high risk showed a trend toward elevation but were not significantly higher than mean serum levels in normal subjects. Mean levels of TNF in BAL of ARDS patients (242 +/- 126 pg/ml) were significantly higher than in normal subjects (9 +/- 5 pg/ml), p less than 0.05. Antigenic levels of TNF were undetectable in approximately half the patients with ARDS or the high-risk state. Levels of TNF in BAL appeared to be highest in the first day of ARDS. There appeared to be no relationship between levels of TNF in serum or BAL and subsequent mortality. However, serum levels of TNF were significantly higher in septic patients than in nonseptic patients, whereas this difference was not apparent in BAL. These results show that functional and antigenic elevations of TNF are present in BAL and perhaps in serum of patients with ARDS or with the high-risk state.

Modulation of Mycobacterium lepraemurium growth in murine macrophages: beneficial effect of tumor necrosis factor alpha and granulocyte-macrophage colony-stimulating factor

Mycobacterium lepraemurium grew progressively in monolayers of Proteose Peptone-elicited macrophages from C57BL/6 mice. Treatment of macrophage monolayers with gamma interferon led to an enhancement of growth of M. lepraemurium in macrophages. Treatment with tumor necrosis factor alpha or granulocyte-macrophage colony-stimulating factor led to restriction of mycobacterial growth in macrophages.

Production of tumour necrosis factor during murine cutaneous leishmaniasis

We have assessed the role of tumour necrosis factor-alpha (TNF) during cutaneous leishmaniasis and demonstrated that significant levels of TNF were released by spleen cells from infected mice after in vitro restimulation with Leishmania major promastigotes. Spleen cells from both genetically resistant and genetically susceptible mice were equally capable of producing TNF. After challenge with bacterial endotoxin, TNF activity could also be demonstrated in the serum of L. major-infected mice and the titres correlated with the course of cutaneous disease in susceptible and resistant mice. TNF did not exert a direct leishmanicidal effect in vitro. Furthermore, our study indicated that macrophages are the source of L. major-induced TNF activity and that its elicitation is dependent on the presence of T cells. These findings suggest that TNF acts in concert with other cytokines produced during L. major infection and that its role depends on the composition of T cell subsets and cytokines present.

Elevated circulating levels of tumor necrosis factor in severe chronic heart failure

BACKGROUND AND METHODS

Although cachexia often accompanies advanced heart failure, little is known about the causes of the cachectic state. To assess the potential role of tumor necrosis factor in the pathogenesis of cardiac cachexia, we measured serum levels of the factor in 33 patients with chronic heart failure, 33 age-matched healthy controls, and 9 patients with chronic renal failure.

RESULTS

Mean (+/- SEM) serum levels of tumor necrosis factor were higher in the patients with heart failure (115 +/- 25 U per milliliter) than in the healthy controls (9 +/- 3 U per milliliter; P less than 0.001). Nineteen of the patients with chronic heart failure had serum levels of tumor necrosis factor greater than or equal to 39 U per milliliter (greater than 2 SD above the mean value for the control group), whereas the remaining 14 patients had serum levels of tumor necrosis factor below this level. The patients with high levels of tumor necrosis factor were more cachectic than those with low levels (82 +/- 3 vs. 95 +/- 6 percent of ideal body weight, respectively; P less than 0.05) and had more advanced heart failure, as evidenced by their higher values for plasma renin activity (2.92 +/- 0.53 vs. 1.06 +/- 0.53 ng per liter per second [10.5 +/- 1.9 vs. 3.8 +/- 1.9 ng per milliliter per hour]; P less than 0.01) and lower serum sodium concentration (135 +/- 1 vs. 138 +/- 1 mmol per liter; P less than 0.05). The group with high levels of tumor necrosis factor also had lower hemoglobin levels (7.82 +/- 0.2 vs. 8.69 +/- 0.4 mmol per liter [12.6 +/- 0.4 vs. 14.0 +/- 0.6 g per deciliter]) and higher values for blood urea nitrogen (19.5 +/- 2.2 vs. 12.5 +/- 1.8 mmol per liter) than the group with low levels of tumor necrosis factor (P less than 0.05 for both). The high levels of tumor necrosis factor were not due solely to decreased renal clearance, however, since the levels in the patients with heart failure were considerably higher than those in the nine patients with chronic renal failure (115 +/- 25 vs. 45 +/- 25 U per milliliter; P less than 0.05).

CONCLUSIONS

These findings indicate that circulating levels of tumor necrosis factor are increased in cachectic patients with chronic heart failure and that this elevation is associated with the marked activation of the renin-angiotensin system seen in patients with end-stage cardiac disease.