Dapsone as treatment adjunct in ARDS.

Multiple pharmacological interventions tested over the last decades have failed to reduce ARDS mortality. This short note recounts past data indicating that (i) neutrophils home along an IL-8 gradient, (ii) in ARDS, massive neutrophil accumulation and degranulation in and along bronchoalveolar spaces contributes to damage and hypoxia, (iii) large increases in IL-8 are one of the chemotaxic signals drawing neutrophils to the ARDS lung, and (iv) old data from dermatology and glioblastoma research showed that the old drug against Hansen's disease, dapsone, inhibits neutrophils' chemotaxis to IL-8. Therefore dapsone might lower neutrophils' contributions to ARDS lung pathology. Dapsone can create methemoglobinemia that although rarely problematic it would be particularly undesirable in ARDS. The common antacid drug cimetidine lowers risk of dapsone related methemoglobinemia and should be given concomitantly.

Erythema Nodosum Leprosum Neutrophil Subset Expressing IL-10R1 Transmigrates into Skin Lesions and Responds to IL-10.

Erythema nodosum leprosum (ENL) is an inflammatory complication in leprosy. Yet, the involvement of ENL neutrophils in the inflammatory response against Mycobacterium leprae remains poorly explored. Our primary aim was to investigate the utility of the surface expression of neutrophil IL-10R1 as an ENL biomarker and, secondarily, to evaluate whether leprosy or healthy M. leprae-stimulated neutrophils produce cytokines and are able to respond to IL-10. We, in this study, describe a subpopulation of circulating neutrophils of ENL patients that exclusively expressed IL-10R1, providing evidence that IL-10R1+ neutrophils are present in ENL lesions. It was also found that ENL neutrophils, but not those of nonreactional leprosy controls, were able to secret detectable levels of TNF ex vivo and the addition of IL-10 blocked TNF release. It was likewise observed that M. leprae-stimulated, healthy neutrophils expressed IL-10R1 in vitro, and ENL-linked cytokines were released by M. leprae-cultured neutrophils in vitro. Moreover, consistent with the presence of a fully functional IL-10R, the addition of IL-10 prevented the release of M. leprae-induced cytokines. Most importantly, dead M. leprae revealed its superior capacity to induce CCL4 and IL-8 in primary neutrophils over live Mycobacterium, suggesting that M. leprae may hamper the inflammatory machinery as an immune escape mechanism.

Expression of CD64 on Circulating Neutrophils Favoring Systemic Inflammatory Status in Erythema Nodosum Leprosum.

Erythema Nodosum Leprosum (ENL) is an immune reaction in leprosy that aggravates the patient´s clinical condition. ENL presents systemic symptoms of an acute infectious syndrome with high leukocytosis and intense malaise clinically similar to sepsis. The treatment of ENL patients requires immunosuppression and thus needs to be early and efficient to prevent both disabilities and permanent nerve damage. Some patients experience multiple episodes of ENL and prolonged use of immunosuppressive drugs may lead to serious adverse effects. Thalidomide treatment is extremely effective at ameliorating ENL symptoms. Several mechanisms have been proposed to explain the efficacy of thalidomide in ENL, including the inhibition of TNF production. Given its teratogenicity, thalidomide is prohibitive for women of childbearing age. A rational search for molecular targets during ENL episodes is essential to better understand the disease mechanisms involved, which may also lead to the discovery of new drugs and diagnostic tests. Previous studies have demonstrated that IFN-γ and GM-CSF, involved in the induction of CD64 expression, increase during ENL. The aim of the present study was to investigate CD64 expression during ENL and whether thalidomide treatment modulated its expression. Leprosy patients were allocated to one of five groups: (1) Lepromatous leprosy, (2) Borderline leprosy, (3) Reversal reaction, (4) ENL, and (5) ENL 7 days after thalidomide treatment. The present study demonstrated that CD64 mRNA and protein were expressed in ENL lesions and that thalidomide treatment reduced CD64 expression and neutrophil infiltrates-a hallmark of ENL. We also showed that ENL blood neutrophils exclusively expressed CD64 on the cell surface and that thalidomide diminished overall expression. Patient classification based on clinical symptoms found that severe ENL presented high levels of neutrophil CD64. Collectively, these data revealed that ENL neutrophils express CD64, presumably contributing to the immunopathogenesis of the disease.

Dapsone in the management of autoimmune bullous diseases.

Dapsone is used in the treatment of autoimmune bullous diseases (AIBD), a group of disorders resulting from autoimmunity directed against basement membrane and/or intercellular adhesion molecules on cutaneous and mucosal surfaces. This review summarizes the limited published data evaluating dapsone as a therapy for AIBD.

The rationale of targeting neutrophils with dapsone during glioblastoma treatment.

Data from past research is presented showing that neutrophils are active participants in new vessel formation in normal physiology, in proliferating human endometrium, in non-cancer pathologies as in the pannus of rheumatoid arthritis, and in various cancers, among them glioblastoma. These data show that interleukin-8 (IL-8) is a major chemokine attracting neutrophil infiltrates in these states. Since the old anti-Hansen's disease drug dapsone inhibits neutrophil migration along an IL-8 gradient towards increasing concentrations, and is used therapeutically for this attribute to good effect in dermatitis herpetiformis, bullous pemphigoid and rheumatoid arthritis, we suggest dapsone may deprive glioblastoma of neutrophil-mediated growth promoting effects. We review past research showing that vascular endothelial growth factor, VEGF, is carried predominantly intracellularly within neutrophils--only 2% of circulating VEGF is found free in serum. Based on the available evidence summarized by the authors, dapsone has a strong theoretical potential to become a useful anti-VEGF, anti-angiogenic agent in glioblastoma treatment.

[Prospects for leprosy treatment via complexation of rifampicin witH iodide and horse-radish root].

A model of leprosy was used to study the therapeutic effect of horse-radish root (HRR) containing peroxidase in combination with rifampicin (RFP) and potassium iodide (PI) as compared to routine combined therapy with RFP and diaminodiphenylsulfonum. Therapy with HRR and iodide showed the best antimicrobial effect than the routine combined therapy. A combination of RFP, HRR, and PI increased the activity of neutrophilic myeliperoxidase produced an anti-inflammatory activity and caused no persistent anemia or toxic effect on the murine liver.

Partial characterization of phagocytic activity in neutrophils of the nine-banded armadillo Dasypus novemcinctus.

Though the armadillo is important as a research model in leprosy studies, the activity of armadillo's neutrophils is an aspect of little research. The aim of this study was carried out to partially characterize the chemotaxis, endocytosis and bacteriocidal ability of the neutrophils found in the nine-banded armadillo (Dasypus novemcinctus). Results showed that the chemotactic activity of the neutrophils, evaluated by the movement of the neutrophils through a nitrocellulose membrane (5 microm) in response to a chemo-attractive substance, was greater towards the armadillo serum (5.16+/-1.35 migration index, p<0.05) than towards the formil methionyl leucil phenylalanine (fMLP, 1.43+/-0.18 migration index) or human serum (0.56+/-0.18 migration index). Regarding endocytic capacity of the neutrophils and the monocytes against Escherichia coli was evaluated by a flow cytometry and using opsonized and non-opsonized E. coli-FITC at the following incubation times: 5, 10, 20, 30 and 60 min. The largest percentage of endocytosis by the neutrophils was 92.32+/-0.12% with opsonized bacteria and 77.73+/-14.33% with non-opsonized bacteria at 10 min incubation time, while the largest percentage of endocytosis by monocytes was 89.94+/-1.40% with opsonized bacteria and 73.07+/-15.6% with non-opsonized bacteria at 20 min incubation time. Evaluation of the bacteriocidal capacity of neutrophils using the methyl-thiazol-tetrazolium salts (MTT) reduction color-measurement assay showed an 89.0+/-10% mortality rate of non-opsonized E. coli and 89.0+10% of opsonized E. coli. In conclusion, the armadillo neutrophils show a good phagocytosis and bacteriocidal activity; however, a deficiency in the migration towards the fMLP was observed. This deficiency could be a cause so that the armadillo neutrophils do not respond quickly to invading microorganism.

Effect of peroxidase in complex with basic antileprosy drugs on liver, blood, and functional activity of phagocytes in mice with experimental leprosy.

Therapeutic effect of lyophilized horseradish peroxidase in complex with the basic antileprosy drugs diaminodiphenylsulfone and rifampicin was studied in experimental leprosy. Oral therapy with drug complexes was more effective than monotherapy. Treatment with drug combinations activated myeloperoxidase in blood neutrophil, produced an antiinflammatory effect, stimulated cell immunity, and had no toxic effect on mouse liver.

Long-lasting T-cell reactivity to Mycobacterium leprae antigens in human volunteers vaccinated with killed M. leprae.

A trial with a candidate anti-leprosy vaccine based on killed Mycobacterium leprae was started in Norway in 1983 to evaluate its toxicity and efficacy to induce cell-mediated immunity (CMI) in BCG-vaccinated healthy volunteers. The vaccinated subjects were found to be free of unacceptable side-effects and their T cells showed elevated proliferative response to M. leprae up to 1 year postvaccination. When tested in 1991, 8 years after vaccination, peripheral blood mononuclear cells from the same volunteers showed a persistent high proliferative response to M. leprae. From a total of 147 T-cell clones established from these subjects, 26 clones were specific to M. leprae and the remaining T-cell clones responded to M. leprae as well as to BCG and other cultivable mycobacteria. The epitopes recognized by the M. leprae-specific T-cell clones were present on several protein antigens including the 18 kDa and the 65 kDa heat shock proteins. A dominant epitope, peptides 38-50 on the M. leprae 18 kDa heat shock protein, which was recognized by M. leprae-specific T cells 1 year after vaccination, was also recognized 8 years after vaccination by the same donor. This is the first report demonstrating the unique property of killed M. leprae with respect to the induction of long-lasting T-cell reactivity towards M. leprae antigens in humans.

The influence of structural modifications of dihydrophenazines on arachidonic acid mobilization and superoxide generation by human neutrophils.

In this study the effects of nine dihydrophenazine derivatives, relative to clofazimine (B663), on the N-formyl-L-methionyl-L-leucyl-L-phenylalanine (FMLP) stimulated release of superoxide anion and on the spontaneous generation of arachidonic acid by human neutrophils were investigated. Previous findings that the pro-oxidative activity of the agents depended largely on the substitution in position 2 of the phenazine molecule and on chlorination in the paraposition of the phenyl and anilino rings were confirmed. Only riminophenazines, but not aposafranone derivatives or the imidazophenazine B621, could enhance superoxide release from activated neutrophils. The lack of chlorination of the phenyl and anilino rings could be compensated for by chlorine substitution in position 7 of the phenazine core. The priming effect of the agents on FMLP stimulated superoxide generation was completely prevented by the phospholipase A2 inhibitor 4-p-bromophenacyl bromide. Furthermore pro-oxidative activities correlated closely with a stimulatory effect of the agents on arachidonic acid release. It was therefore concluded that dihydrophenazine derivatives with pro-oxidative properties can prime neutrophils for FMLP-stimulated superoxide release by modulation of phospholipase A2 activity.

Apparent involvement of phospholipase A2, but not protein kinase C, in the pro-oxidative interactions of clofazimine with human phagocytes.

The anti-leprosy agent, clofazimine, at concentrations of 0.1-5 micrograms/ml caused a dose-related, stimulus-non-specific (N-formyl-methionyl-leucyl-phenylalanine, calcium ionophore, opsonised zymosan, arachidonic acid and phorbol myristate acetate) potentiation of superoxide generation by human neutrophils in vitro without affecting basal oxidative responses. The pro-oxidative interactions of clofazimine with neutrophils were eliminated by the phospholipase A2 inhibitor 4-p-bromophenacyl bromide but not by the protein kinase C (PKC) inhibitor H-7. In support of these observations clofazimine promoted the release of radiolabeled arachidonic acid from neutrophil membrane phospholipids but did not influence the activity of PKC in cytosolic extracts of neutrophils or of purified PKC from rat brain. Pro-oxidative interactions of clofazimine with human phagocytes may contribute to the intraphagocytic antimycobacterial activity of this agent.

Efecto inhibitorio de la endocitosis en leucocitos polimorfonucleares causado por talidomida / Inhibitory effect of endocytosis in polimophonuclear celis caused by thalidomide

La talidomida es un medicamento útil para el tratamiento de la lepra lepromatosa reaccional y se conoce parcialmente su mecanismo de acción. Para entender mejor las propiedades de este fármaco se estudió la función fagocítica de los polimorfonucleares en presencia de talidomida. Los resultados indican que este fármaco disminuye de manera significativa la fagocitosis in vitro y, probablemente mediante el mismo mecanismo, ayuda a disminuir el proceso inflamatorio de la reacción leprosa y otras enfermedades inflamatorias de la piel

Enhancement by clofazimine and inhibition by dapsone of production of prostaglandin E2 by human polymorphonuclear leukocytes in vitro.

The effects of the antileprosy agents clofazimine and dapsone (1 to 10 micrograms/ml) on the spontaneous and stimulated release of prostaglandin E2 (PG E2) by human polymorphonuclear leukocytes (PMNL) in vitro have been investigated. PMNL were obtained from normal adult volunteers and three patients with leprosy (two borderline lepromatous and one subpolar lepromatous leprosy). The synthetic chemotactic tripeptide N-formyl-L-methionyl-L-leucyl-L-phenylalanine (FMLP) at a concentration of 10(-7) M was used as the stimulant of PG E2 synthesis. None of the test agents at the concentrations used inhibited the binding of radiolabeled FMLP to PMNL. However, dapsone at 5 and 10 micrograms/ml inhibited the spontaneous and FMLP-induced release of PG E2 by PMNL. Clofazimine, on the other hand, significantly increased both the spontaneous and the FMLP-induced synthesis of PG E2 by PMNL. The enhancing effects of clofazimine on FMLP-mediated synthesis of PG E2 were particularly striking and were observed at concentrations of 1 to 10 micrograms of the drug per ml. Measurements of PMNL spontaneous and FMLP-induced synthesis of PG E2 in the presence of both clofazimine and dapsone (5 micrograms/ml) indicated that the two drugs are mutually antagonistic. PMNL from both normal control subjects and patients with leprosy were equally sensitive to these effects of clofazimine and dapsone. The immunostimulatory and immunosuppressive properties of dapsone and clofazimine, respectively, may be related to the opposite effects of these agents on PG E2 synthesis in human leukocytes.

Thalidomide: use and possible mode of action in reactional lepromatous leprosy and in various other conditions.

The literature concerning the use and possible mode of action of thalidomide in reactional lepromatous leprosy and in various other conditions is reviewed. Although it has no action against the leprosy bacillus, its value in the treatment of the adverse reactions in this type of leprosy is well established, many leprologists considering it to be superior to any other drug for this purpose. Its efficacy in actinic prurigo is also impressive, and there are reports suggesting benefit in discoid lupus erythematosus. By contrast, its reported action in a number of other conditions, including severe aphthous stomatitis, Behçet's syndrome, pyoderma gangrenosum, nodular prurigo, and postherpetic neuralgia, needs confirmation in a larger number of cases, backed in some instances by clinical trial. The mechanism of action of this drug may be related to (1) anti-inflammatory effects, particularly an inhibition of neutrophil chemotaxis, (2) immunosuppressive effects, or (3) effects on neural tissue. Furthermore, structure-activity studies may allow separation of these and other possible effects. This review is in no way intended to lend support to the indiscriminate use of a potentially hazardous drug in various diseases of unknown cause, but rather to draw attention to a number of conditions in which the drug has been found effective. The further judicious use of thalidomide or a nonteratogenic analogue, with careful observation of results, may contribute to knowledge of the underlying pathology in some of these conditions, and possibly also to the mechanism of action of the drug itself.

Effects of clofazimine alone or combined with dapsone on neutrophil and lymphocyte functions in normal individuals and patients with lepromatous leprosy.

The effects of clofazimine on neutrophil activities such as random motility, migration to the leukoattractants endotoxin-activated serum and N-formyl-L-methionyl-L-leucyl-L-phenylalanine phagocytosis of Candida albicans, postphagocytic hexose-monophosphate shunt activity, and myeloperoxidase-mediated iodination and the effects of clofazimine on lymphocyte transformation to mitogens were assessed in vitro and after ingestion of the drug by normal individuals and patients with lepromatous leprosy. For in vitro studies, the concentration range of the drug investigated was 10(-6) M to 10(-2) M. for in vivo studies, subjects ingested 200 mg of clofazimine daily for a period of 5 days. At concentrations of 5 X 10(-6) M to 5 X 10(-3) M clofazimine caused a progressive dose-dependent inhibition of neutrophil motility without detectable effects on phagocytosis, postphagocytic hexose-monophosphate shunt activity, or myeloperoxidase-mediated iodination. Over the same concentration range, clofazimine inhibited lymphocyte transformation. The inhibitory effect on neutrophil motility was associated with a spontaneous stimulation of oxidative metabolism and could be prevented by coincubation of dapsone with clofazimine. after ingestion of clofazimine responsiveness of lymphocytes to mitogens was decreased in normal volunteers and leprosy patients: neutrophil motility in normal individuals was likewise inhibited.

Effects of ascorbate on normal and abnormal leucocyte functions.

The stimulatory effects of ascorbate on neutrophil motility in vitro and in vivo and lymphocyte transformation to mitogens following ingestion or intravenous injection of ascorbate have been found to be related entirely to inhibition of the autooxidative effect of the myeloperoxidase/hydrogen peroxide/halide system (MPO/H2O2/halide system). Stimulation of neutrophil migration and lymphocyte transformation following a single intravenous injection of 1 g of ascorbate was associated with inhibition of the MPO/H2O2/halide system. The immunostimulatory activity and peroxidase inhibitory activity was related entirely to the serum ascorbate level. The relationship between inhibition of the peroxidase/h2O2/halide system and stimulation of neutrophil motility and lymphocyte mitogen-induced transformation was further established by using the horseradish peroxidase (HRP)/H2O2/halide system in vitro. Neutrophils and lymphocytes, exposed to this system, manifested markedly impaired chemotactic responsiveness and mitogen-induced transformation, respectively. However inclusion of ascorbate with the peroxidative system protected the neutrophils and lymphocytes from these inhibitory effects. Further studies in 3 patients with chronic granulomatous disease (CGD) and 10 patients with bronchial asthma suggested that ascorbate may be of value to improve the primary immunological abnormalities (neutrophil motility and antimicrobial activity) in CGD and the secondary abnormalities (neutrophil motility and lymphocyte transformation) found in some individuals with bronchial asthma.