Experimental Modeling of Leprosy in BALB/c, BALB/c Nude, CBA, and C57BL/6ТNF-/- Mice.

Leprosy was modeled in an experiment on BALB/c, BALB/cNude, CBA, and C57BL/6ТNF-/- mice using three Mycobacterium leprae strains obtained from patients with a diagnosis of A30 according to ICD-10 from different regions of the Russian Federation. Proliferation of M. leprae of the used strains showed a temporal-quantitative dependence on the used mouse line. CBA and BALB/cNude mice were optimal for strain R and BALB/c and BALB/cNude lines were optimal for strain I. BALB/cNude mice infected with strain I had low lifespan. M. leprae strain M showed low proliferation activity in BALB/cNude and C57BL/6ТNF-/- mice.

[Phagocytosis of Mycobacterium leprae down-regulates anti-microbial activity of murine macrophages against Mycobacterium intracellulare].

Patients with highly bacillated lepromatous leprosy (LL) essentially lack T cell-mediated immune responses specific to Mycobacterium leprae (ML) antigens, resulting in severely impaired host resistance to leprosy bacilli. Such type of immune unresponsiveness characteristic of LL patients is mainly attributable to markedly depressed T cell ability to activate/expand in response to ML antigens. In this study, we examined profiles of antimycobacterial activity of macrophages, which phagocytized leprosy bacilli, because there is another possibility that, in LL patients, host macrophages in the leprosy lesions are impaired in their antimicrobial activity due to their interaction with infected leprosy bacilli, particularly cellular events through binding with and/or internalization of the pathogens, thereby causing the reduction in host resistance to ML pathogens. The present study indicated the following. First, the anti-M. avium complex activity of murine peritoneal macrophages was significantly reduced when they had phagocytosed heat-killed leprosy bacilli. Second, infection of macrophages with leprosy bacilli did not affect macrophage-mediated suppressor activity against T cell proliferative response to Concanavalin A. These findings indicate that macrophage's intracellular signaling pathways that are up-regulated in response to phagocytosis of leprosy bacilli are linked to the signaling cascades participating in macrophage antimicrobial functions, but not cross-talk with those allowing the expression of macrophage's suppressor activity against T cell functions.

The activity of several newer antimicrobials against logarithmically multiplying M. leprae in mice.

INTRODUCTION: Moxifloxacin, rifampicin, rifapentine, linezolid, and PA 824, alone and in combination, have been previously administered, as single doses and five times daily doses, to M. leprae infected mice during lag phase multiplication and were each found to have some bactericidal activity. DESIGN: The fluroquinolones, ofloxacin, moxifloxacin and gatifloxacin, (50 mg/kg, 150 mg/kg and 300 mg/kg) and the rifamycins (5 mg/kg, 10 mg/kg, and 20 mg/kg), rifampicin and rifapentine, were evaluated alone and in combination for bactericidal activity against M. leprae using the mouse footpad model during logarithmic multiplication. Linezolid and PA 824 were similarly evaluated alone and linezolid in combination with rifampicin, minocycline and ofloxacin. RESULTS: The three fluroquinolones and rifamycins were found alone and in combination to be bactericidal at all dosage schedules. PA 824 had no activity against M. leprae, while linezolid at a dose of 25 mg/kg was bacteriostatic, and progressively more bactericidal at doses of 50 mg/kg and 100 mg/kg. No antagonisms were detected between any of these drugs when used in combinations. CONCLUSION: Moxifloxacin, gatifloxacin, rifapentine and linezolid were found bactericidal against rapidly multiplying M. leprae.

Antileprosy activity and preliminary toxicological characteristics of some dialkyldithiocarbamate derivatives.

Antileprosy activity of dialkyldithiocarbamate derivatives was studied in experiments on mice infected with M. leprae into paw pads. We found that 2-diethyldithiocarbamoyl-3-cyano-5-nitropyridine is the most promising antileprosy agent; it effectively suppresses multiplication of M. leprae and is well tolerated under conditions of chronic animal experiment.

[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.

Study of antileprosy activities of some dialkyldithiocarbamate derivatives.

Effects of some dialkyldithiocarbamate derivatives on multiplication of M. leprae were studied in infected mice. Compounds significantly suppressing M. leprae proliferation were selected. By antibacterial activity one of these compounds was superior to dapsone, the main antileprosy drug.

Synthesis and antileprosy activity of some dialkyldithiocarbamates.

OBJECTIVES: To investigate the antileprosy potential of a set of original compounds with antimycobacterial activity. METHODS: We developed a facile synthesis of 2-chloro-3-cyano-5-nitropyridine and synthesized a series of 3-cyano-2-dialkyldithiocarbamoyl-5-nitropyridine derivatives. In vivo therapeutic efficacy against Mycobacterium leprae was assessed in the infected mouse footpad model. RESULTS: The compounds were active in vitro against Mycobacterium smegmatis, Mycobacterium aurum, Mycobacterium vaccae and Mycobacterium fortuitum, with MICs generally in the range of 0.4-6.25 mg/L. Reduction of the bacterial load in vivo in the mouse footpad and toxic side effects were dependent on the individual structure of the compounds and on the doses applied. Compounds 2a, 3a and 3b reduced the number of M. leprae by two orders of magnitude, comparable to the effect of dapsone. Co-administration of compounds 2a and 3a with dapsone synergistically enhanced the activity. In addition, these compounds were well tolerated over the treatment period of 7.5 months. CONCLUSIONS: Individual synthetic dithiocarbamate derivatives have promising antileprosy activity.

[Chronobiological aspects of the action of diaminodiphenylsulfone on hematological mice induces in summer and winter seasons ]. / Khronobiologicheskie aspekty vliianiia diaminodifenilsul'fona na gematologicheskie pokazateli u myshei v letnii i zimnii sezony goda.

Mice experiments were made to study effects of diaminodiphenylsulphone (DDS)--basic antileprous drug--on circadian rhythms of hemoglobin levels, counts of red cells and leukocytes. The time of the drug administration varied within the day while seasons of the year were two--winter and summer. Blood components were studied with unified methods. The results of the study showed that DDS has significant effects on the structure of circadian rhythms of the above blood components. These effects correlate with the season of the year and time of DDS administration.

Effects of horseradish root on functional activity of phagocytes, total blood cell count, and state of the liver in mice with experimental leprosy.

Therapy of experimental leprosy with dried and grated horseradish root administered perorally in a dose of 300 mg/kg mixed food and treatment with purified horseradish peroxidase increased myeloperoxidase activity of blood neutrophils, enhanced antimicrobial functions of phagocytes, decreased leukocytosis, normalized total blood cell count, and produced no adverse effects on the functional state of the liver in mice.

Dosage and site of entry influence growth and dissemination of Mycobacterium leprae in T900r mice.

The role of dosage of Mycobacterium leprae and the environment of the inoculated site, in producing leprosy lesions in immunologically-suppressed, highly-susceptible T900r mice, was investigated. Various doses of M. leprae, i.e., 10(7), 10(6), 10(5), 10(4), were inoculated into both flanks and footpads of two different groups of mice. The sites of inoculation were biopsied for histopathological examination and for M. leprae counts at the end of 6, 8 and 12 months. M. leprae multiplied at the infected site and disseminated [figure: see text] to other parts of the body at all concentrations in the mice that were infected in the footpad with a temperature of 31 degrees C. In animals inoculated at the flanks with a temperature of 37 degrees C, multiplication was recorded only when the dosage of M. leprae was high and there was no dissemination of the organism in any of them. The temperature at the site of entry and the dose of infecting M. leprae may play an important role in the development of leprosy in susceptible individuals exposed to M. leprae.

Drug resistant-Mycobacterium leprae--results of mouse footpad studies from a laboratory in south India.

Out of 265 biopsies of leprosy patients received at the Experimental Pathology Laboratory of Schieffelin Leprosy Research and Training Centre from 1987 to 1997 for evaluating resistant strains of M. leprae, using the mouse footpad technique, 49 showed resistant strains of M leprae to varying concentrations of dapsone, rifampicin and clofazimine. 23 (47%) of these were from a control area. With 369 skin-smear positive multibacillary (MB) patients as the risk group (denominator), 23 (6.23%) were resistant to one or more drugs. 18 (4.88%) had dapsone resistance, 5 (1.36%) were resistant to rifampicin and 9 (2.44%) had resistance to low concentrations of clofazimine (0.0001%). Out of the 23 biopsies with drug resistance from the control area, primary dapsone resistance was seen in 7 (30%) biopsies and secondary dapsone resistance in 11 (48%). Primary rifampicin resistance was seen in 4 (17.4%) patients, secondary rifampicin resistance in 1 (4.35%) and primary clofazimine resistance in 7 (30%). 3 (13%) of the strains showed secondary clofazimine resistance. One biopsy had resistant strains to all the three drugs. In a control area where properly supervised effective multidrug therapy (MDT) was regularly administered over the years, the emergence of drug resistance is negligible. It may not be the case if the content, duration and regularity of the drug regimen were not satisfactory. Aware of the possible shortcomings in mass administration of MDT, it is emphasized that mouse footpad studies on drug resistance should be made available at least in endemic areas where the incidence of the disease has not changed despite good MDT coverage in order to monitor the emergence of drug resistance. Research into molecular biological identification of drug resistant-M.leprae should be intensified. These steps would help to institute timely measures to check the spread of any drug-resistant organisms in the community.

Effects of horseradish root on functional activity of phagocytes, total blood cell count, and state of the liver in mice with experimental leprosy

Therapy of experimental leprosy with dried and grated horseradish root administered perorally in a dose of 300 mg/kg mixed food and treatment with purified horseradish peroxidase increased myeloperoxidase activity of blood neutrophils, enhanced antimicrobial functions of phagocytes, decreased leukocytosis, normalized total blood cell count, and produced no adverse effects on the functional state of the liver in mice.

Drug resistant-Mycobacterium leprae--results of mouse footpad studies from a laboratory in south India

Out of 265 biopsies of leprosy patients received at the Experimental Pathology Laboratory of Schieffelin Leprosy Research and Training Centre from 1987 to 1997 for evaluating resistant strains of M. leprae, using the mouse footpad technique, 49 showed resistant strains of M leprae to varying concentrations of dapsone, rifampicin and clofazimine. 23 (47%) of these were from a control area. With 369 skin-smear positive multibacillary (MB) patients as the risk group (denominator), 23 (6.23%) were resistant to one or more drugs. 18 (4.88%) had dapsone resistance, 5 (1.36%) were resistant to rifampicin and 9 (2.44%) had resistance to low concentrations of clofazimine (0.0001%). Out of the 23 biopsies with drug resistance from the control area, primary dapsone resistance was seen in 7 (30%) biopsies and secondary dapsone resistance in 11 (48%). Primary rifampicin resistance was seen in 4 (17.4%) patients, secondary rifampicin resistance in 1 (4.35%) and primary clofazimine resistance in 7 (30%). 3 (13%) of the strains showed secondary clofazimine resistance. One biopsy had resistant strains to all the three drugs. In a control area where properly supervised effective multidrug therapy (MDT) was regularly administered over the years, the emergence of drug resistance is negligible. It may not be the case if the content, duration and regularity of the drug regimen were not satisfactory. Aware of the possible shortcomings in mass administration of MDT, it is emphasized that mouse footpad studies on drug resistance should be made available at least in endemic areas where the incidence of the disease has not changed despite good MDT coverage in order to monitor the emergence of drug resistance. Research into molecular biological identification of drug resistant-M.leprae should be intensified. These steps would help to institute timely measures to check the spread of any drug-resistant organisms in the community.

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.

Dendritic epidermal gamma/delta T cells (DETC) activated in vivo proliferate in vitro in response to Mycobacterium leprae antigens.

BACKGROUND: gamma/delta T-cell receptor (TCR)+ dendritic epidermal T cells (DETC) are part of a primitive defense system in the skin; they are capable of responding only to a limited number of antigens. The aim of the present study was to test whether DETC can proliferate in vitro in response to antigens of Mycobacterium leprae. METHODS: DETC were obtained from CBA mouse ear skin by trypsinization and Histopaque gradient centrifugation. The resulting epidermal cell suspension contained up to 20% DETC, as analyzed by the fluorescence activated cell sorter (FACS) after staining with anti-Thy-1 or anti-gamma/delta TCR monoclonal antibodies (mAbs). The freshly isolated cells, or DETC cultured up to 4 weeks with interleukin-2 (IL-2), were exposed in vitro for up to 6 days to varying doses of the following M. leprae antigens: (1) integral (live) M. leprae bacilli; (2) Dharmendra antigen; and (3) PGL-1 (phenolic glycolipid of M. leprae). The DETC response was assessed by tritiated thymidine (3H-TdR) incorporation. RESULTS: The freshly isolated DETC, or DETC cultured up to 4 weeks with IL-2, did not respond significantly to any of the M. leprae antigens, although at the same time they were able to respond vigorously to concanavalin A (Con A), as positive control. If, however, DETC were isolated from skin, painted 7 days before with croton oil (10 microL/cm2 to cause irritant dermatitis, they were able to respond to all M. leprae antigens by a 3-4-fold incrase in the 3H-TdR uptake. The most effective stimulator was a 1 : 1 mixture of Dharmendra and PGL-1 (0. 01 microg/mL), which was as effective as 10-fold higher doses of either antigen alone. Cell counts confirmed that increased DNA synthesis was associated with cell proliferation. Experiments employing alpha/beta-TCR CBA murine spleen cells and epidermal cell suspension treated with anti-gamma/delta or antialpha/beta mAbs + C' proved that only the gamma/delta DETC were the responder cells to M. leprae antigens. CONCLUSIONS: The results suggest that activation of DETC in vivo may make them responsive to M. leprae antigens. A significant increase in the number of class II major histocompatibility complex (MHC) positive, nondendritic cells was observed in the croton oil-treated epidermis. We hypothesize that croson oil-induced upregulation of class II MHC expression, which endows epidermal cells with antigen-presenting capabilities, might be an important factor in vivo in delivering an immunogenic signal to resident DETC in the skin.

Effect of peroxidase on the development of experimental leprosy in mice after intraplantar infection.

Lyophilized horseradish peroxidase (activity 100 U/mg) administered per os in a dose of 100-200 mg/kg fodder enhanced bactericidal activity of phagocytes in mice experimentally infected with Mycobacterium leprae, which manifested in suppression of M. leprae growth in comparison with untreated controls.

Effects of peroxidase therapy on functional state of the liver and phagocytes and blood cell counts in mice with experimental leprosy.

We studied the effects of long-term therapy with horseradish peroxidase administered orally to mice with experimental leprosy. Horseradish peroxidase stimulated phagocyte myeloperoxidase activity that correlated with their functional activity, reduced leukocytosis, and produced no adverse effects on the liver.

Relapse as histoid leprosy after receiving multidrug therapy (MDT); a report of three cases.

The histoid type of leprosy has been described as occurring in lepromatous leprosy patients who relapse after many years of apparently successful dapsone monotherapy. Three patients who had received the World Health Organization-recommended regimens of multidrug therapy (WHO/MDT) relapsed as histoid leprosy 12-15 years after completion of treatment. In one patient, through mouse foot pad studies, the bacilli were found to be sensitive to rifampin and clofazimine and resistant to dapsone. In the other two patients mouse foot pad studies were inconclusive. The patients were re-started on WHO/MDT. Two patients took regular treatment and improved, both clinically and bacteriologically. One patient was irregular in treatment, and 1 year after re-starting WHO/MDT nodules were still present although the bacterial index had fallen slightly.