In 2004, a novel mechanism of cellular death, called 'NETosis', was described in neutrophils. This mechanism, different from necrosis and apoptosis, is characterized by the release of chromatin webs admixed with microbicidal granular proteins and peptides (NETs). NETs trap and kill a variety of microorganisms. Diverse microorganisms, including Mycobacterium tuberculosis, are NET inducers in vitro. The aim of this study was to examine whether M. tuberculosis can also induce NETs in vivo and if the NETs are bactericidal to the microorganism. Guinea pigs were intradermally inoculated with M. tuberculosis H37Rv, and the production of NETs was investigated at several time points thereafter. NETs were detected as early as 30 min post-inoculation and were clearly evident by 4 h post-inoculation. NETs produced in vivo contained DNA, myeloperoxidase, elastase, histones, ROS and acid-fast bacilli. Viable and heat-killed M. tuberculosis, as well as Mycobacterium bovis BCG were efficient NET inducers, as were unilamellar liposomes prepared with lipids from M. tuberculosis. In vitro, guinea pig neutrophils also produced NETs in response to M. tuberculosis. However, neither the in vivo nor the in vitro-produced NETs were able to kill M. tuberculosis. Nevertheless, in vivo, neutrophils might propitiate recruitment and activation of more efficient microbicidal cells.

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The lack of granular MPO in mature macrophages, and the predilection of mycobacteria to infect these cells are two situations that favor the development of tuberculosis and related diseases, such as leprosy and Buruli ulcer.

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A small but relatively constant proportion (3-5%) of mice chronically infected with Mycobacterium lepraemurium (MLM) develops bilateral paralysis of the rear limbs. The aim of the study was to investigate whether or not the bilateral leg palsy results from nerve involvement. Direct bacterial nerve infection or acute/delayed inflammation might possibly affect the nerves. Therefore, palsied animals were investigated for the presence of: (a) histopathological changes in the leg tissues including nerves, bones and annexes, and (b) serum antibodies to M. lepraemurium and M. leprae lipids, including phenolic glycolipid I from M. leprae . Histopathological study of the palsied legs revealed that the paralysis was not the result of direct involvement of the limb nerves, as neither bacilli nor inflammatory cells were observed in the nerve branches studied. Antibodies to brain lipids and cardiolipin were not detected in the serum of the palsied animals, thus ruling out an immune response to self-lipids as the basis for the paralysis. Although high levels of antibodies to MLM lipids were detected in the serum of palsied animals they were not related to limb paralysis, as the nerves of the palsied legs showed no evidence of inflammatory damage. In fact, nerves showed no evidence of damage. Paralysis resulted from severe damage of the leg bones. Within the bones the bone marrow became replaced by extended bacilli-laden granulomas that frequently eroded the bone wall, altering the normal architecture of the bone and its annexes, namely muscle, tendons and connective tissue. Although this study rules out definitively the infectious or inflammatory damage of nerves in murine leprosy, it opens a new avenue of research into the factors that participate in the involvement or the sparing of nerves in human and murine leprosy, respectively.

Leprosy is a disease consisting of a spectrum of clinical, bacteriological, histopathological and immunological manifestations. Tuberculoid leprosy is frequently recognized as the benign polar form of the disease, while lepromatous leprosy is regarded as the malignant form. The different forms of leprosy depend on the genetic and immunological characteristics of the patient and on the characteristics of the leprosy bacillus. The malignant manifestations of lepromatous leprosy result from the mycobacterial-specific anergy that develops in this form of the disease. Using murine leprosy as a model of anergy in this study, we first induced the development of anergy to Mycobacterium lepraemurium (MLM) in mice and then attempted to reverse it by the administration of dialysable leucocyte extracts (DLE) prepared from healthy (HLT), BCG-inoculated and MLM-inoculated mice. Mice inoculated with either MLM or BCG developed a robust cell-mediated immune response (CMI) that was temporary in the MLM-inoculated group and long-lasting in the BCG-inoculated group. DLE were prepared from the spleens of MLM- and BCG-inoculated mice at the peak of CMI. Independent MLM intradermally-inoculated groups were treated every other day with HLT-DLE, BCG-DLE or MLM-DLE, and the effect was documented for 98 days. DLE administered at a dose of 1.0 U (1 × 10(6) splenocytes) did not affect the evolution of leprosy, while DLE given at a dose of 0.1 U showed beneficial effects regardless of the DLE source. The dose but not the specificity of DLE was the determining factor for reversing anergy.

SummaryRheumatoid arthritis is a disabling autoimmune disease with a high global prevalence. Treatment with disease‐modifying anti‐arthritic drugs (DIMARDs) has been routinely used with beneficial effects but with adverse long‐term consequences; novel targeted biologics and small‐molecule inhibitors are promising options. In this study, we investigated whether purified omega unsaturated fatty acids (ω‐UFAs) and dialysable leukocyte extracts (DLEs) prevented the development of arthritis in a model of collagen‐induced arthritis (CIA) in mice. We also investigated whether the transcription factor NF‐κB and the NLRP3 inflammasome were involved in the process and whether their activity was modulated by treatment. The development of arthritis was evaluated for 84 days following treatment with nothing, dexamethasone, DLEs, docosahexaenoic acid, arachidonic acid, and oleic acid. Progression of CIA was monitored by evaluating clinical manifestations, inflammatory changes, and histological alterations in the pads’ articular tissues. Both DLEs and ω‐UFAs led to an almost complete inhibition of the inflammatory histopathology of CIA and this was concomitant with the inhibition of NF‐kB and the inhibition of the activation of NLRP3. These data suggest that ω‐UFAs and DLEs might have NF‐κB as a common target and that they might be used as ancillary medicines in the treatment of arthritis.

Background: The Mediterranean Diet (MD) has been linked to a reduced risk of developing degenerative diseases, including atherosclerosis, heart stroke, diabetes, arthritis and cancer. However, only a few scientific investigations have attempted to validate this impression. The ingredients of the MD include significant amounts of omega (ω3, ω6, and ω9) unsaturated fatty acids (UFAs). A few studies of these UFAs in the prevention or treatment of arthritis have yielded controversial results, but a general belief regarding their beneficial effects has prevailed. Objective: To investigate the effects of three relevant UFAs, namely Docosahexaenoic Acid (DHA), Arachidonic Acid (AA), and Oleic Acid (OA) (ω3, ω6, and ω9, respectively), in the development of arthritis using a murine model of Collagen-Induced Arthritis (CIA). Methods: DBA-1 mice were immunized with chicken collagen type II (CII) and were subsequently treated with ω-UFAs for 53 days. Dexamethasone (DEXA) was used as a positive anti-inflammatory agent. The effect of the treatments was evaluated through several parameters: inflammation indices, antibody levels, cell proliferation, and histopathological findings. Results and Conclusion: The anti-inflammatory effect of the tested substances was inversely correlated with the histopathological findings: a greater antiinflammatory effect was associated with less articular damage. Oleic acid (ω9) was the most efficient anti-inflammatory UFA, followed by DHA and then AA. DEXA completely inhibited the development of arthritis, whereas the untreated CII-immunized mice developed the most severe articular damage. DBA-1 mice with CII-induced arthritis constitute an adequate model for the study of arthritis and its treatment.