Antimicrobial Activity of Neutrophils Against Mycobacteria.

The mycobacterium genus contains a broad range of species, including the human pathogens M. tuberculosis and M. leprae. These bacteria are best known for their residence inside host cells. Neutrophils are frequently observed at sites of mycobacterial infection, but their role in clearance is not well understood. In this review, we discuss how neutrophils attempt to control mycobacterial infections, either through the ingestion of bacteria into intracellular phagosomes, or the release of neutrophil extracellular traps (NETs). Despite their powerful antimicrobial activity, including the production of reactive oxidants such as hypochlorous acid, neutrophils appear ineffective in killing pathogenic mycobacteria. We explore mycobacterial resistance mechanisms, and how thwarting neutrophil action exacerbates disease pathology. A better understanding of how mycobacteria protect themselves from neutrophils will aid the development of novel strategies that facilitate bacterial clearance and limit host tissue damage.

Neutrophil extracellular traps contribute to the pathogenesis of leprosy type 2 reactions.

Up to 50% of patients with the multibacillary form of leprosy are expected to develop acute systemic inflammatory episodes known as type 2 reactions (T2R), thus aggravating their clinical status. Thalidomide rapidly improves T2R symptoms. But, due to its restricted use worldwide, novel alternative therapies are urgently needed. The T2R triggering mechanisms and immune-inflammatory pathways involved in its pathology remain ill defined. In a recent report, we defined the recognition of nucleic acids by TLR9 as a major innate immunity pathway that is activated during T2R. DNA recognition has been described as a major inflammatory pathway in several autoimmune diseases, and neutrophil DNA extracellular traps (NETs) have been shown to be a prime source of endogenous DNA. Considering that neutrophil abundance is a marked characteristic of T2R lesions, the objective of this study was to investigate NETs production in T2R patients based on the hypothesis that the excessive NETs formation would play a major role in T2R pathogenesis. Abundant NETs were found in T2R skin lesions, and increased spontaneous NETs formation was observed in T2R peripheral neutrophils. Both the M. leprae whole-cell sonicate and the CpG-Hlp complex, mimicking a mycobacterial TLR9 ligand, were able to induce NETs production in vitro. Moreover, TLR9 expression was shown to be higher in T2R neutrophils, suggesting that DNA recognition via TLR9 may be one of the pathways triggering this process during T2R. Finally, treatment of T2R patients with thalidomide for 7 consecutive days resulted in a decrease in all of the evaluated in vivo and ex vivo NETosis parameters. Altogether, our findings shed light on the pathogenesis of T2R, which, it is hoped, will contribute to the emergence of novel alternative therapies and the identification of prognostic reactional markers in the near future.

Type 2 leprosy reaction with Sweet's syndrome-like presentation.

Leprosy is a chronic disease characterized by manifestations in the peripheral nerves and skin. The course of the disease may be interrupted by acute phenomena called reactions. This article reports a peculiar case of type 2 leprosy reaction with Sweet's syndrome-like features as the first clinical manifestation of leprosy, resulting in a delay in the diagnosis due to unusual clinical presentation. The patient had clinical and histopathological features reminiscent of Sweet's syndrome associated with clusters of vacuolated histiocytes containing acid-fast bacilli isolated or forming globi. Herein, it is discussed how to recognize type 2 leprosy reaction with Sweet's syndrome features, the differential diagnosis with type 1 leprosy reaction and the treatment options. When this kind of reaction is the first clinical presentation of leprosy, the correct diagnosis might be not suspected clinically, and established only with histopathologic evaluation.

Type 2 leprosy reaction with Sweet's syndrome-like presentation

Abstract Leprosy is a chronic disease characterized by manifestations in the peripheral nerves and skin. The course of the disease may be interrupted by acute phenomena called reactions. This article reports a peculiar case of type 2 leprosy reaction with Sweet's syndrome-like features as the first clinical manifestation of leprosy, resulting in a delay in the diagnosis due to unusual clinical presentation. The patient had clinical and histopathological features reminiscent of Sweet's syndrome associated with clusters of vacuolated histiocytes containing acid-fast bacilli isolated or forming globi. Herein, it is discussed how to recognize type 2 leprosy reaction with Sweet's syndrome features, the differential diagnosis with type 1 leprosy reaction and the treatment options. When this kind of reaction is the first clinical presentation of leprosy, the correct diagnosis might be not suspected clinically, and established only with histopathologic evaluation.

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.

Thalidomide as an immunotherapeutic agent: the effects on neutrophil-mediated inflammation.

Thalidomide was developed in the 1950s as a sedative drug and withdrawn in 1961 because of its teratogenic effects, but has been rediscovered as an immuno-modifying drug. It has been administered successfully for the treatment of erythema nodosum leprosum, aphthous ulceration in HIV disease, inflammatory bowel diseases, and multiple myeloma. So far, investigations into the mode of action of thalidomide have focused on lymphocytes and vascular endothelial cells and have shown that this agent inhibits the production of tumor necrosis factor (TNF)-alpha and is an inhibitor of tumor angiogenesis. Recently, other immunological effects of this drug have been gaining attention, including attenuation of neutrophil activation and inhibition of myelo-proliferative responses. In autoimmune diseases, inflammation is characterized by an influx of granulocytes, and the association of granulocytes with gastrointestinal ulcer formation or rheumatic arthritis has been well documented. The suppressive effect of thalidomide on the activation of the nuclear transcription factor NF-(kappa)B may explain these effects of thalidomide. NF-(kappa)B is retained in the cytoplasm with I(kappa)B(alpha), and is activated by a wide variety of inflammatory stimuli including TNF, IL-1 and endotoxin followed by its translocation to the nucleus. Constitutive activation of NF-(kappa)B has been detected in various inflammatory diseases, while angiogenesis and organogenesis also require NF-(kappa)B activation. Thalidomide, on the other hand, has been shown to selectively suppress NF-(kappa)B activation induced by inflammatory mediators. NF-(kappa)B is known to be located downstream of proliferative and/or survival signaling induced by growth factors, which regulate anti-apoptotic genes. Myeloid cells in vitro, however, have been found to proceed to apoptosis as the result of the treatment with thalidomide and subsequent inactivation of NF-(kappa)B. These findings are consistent with clinical symptoms that showed the recovery from leukocytosis and/or neutrophilia after the administration of thalidomide. These findings shed new light on the anti-inflammatory properties of thalidomide and suggested that they may inhibit granulocyte-mediated tissue injury.

A rare variant of erythema nodosum leprosum: a case report.

We report a patient with lepromatous leprosy who developed a rare variant of type-2 lepra reaction, characterized by pustular lesions, on switching from WHO multi drug therapy (MDT) to ofloxacin-aided MDT.

Cytodiagnosis of erythema nodosum leprosum. A case report.

BACKGROUND: The application of cytology in leprosy has been restricted to the evaluation of morphologic and bacterial indices by slit skin smears to facilitate diagnosis of cases according to the Ridley-Jopling scale. Isolated reports have now documented the use of fine needle aspiration cytology (FNAC) in the diagnosis of leprosy. CASE: A 45-year-old male presented with the abrupt onset of multiple nodular eruptions all over the body. The clinical diagnosis was Sweet's syndrome. FNAC showed numerous neutrophils in a background of foamy macrophages. Special stains revealed the presence of a large number of fragmented acid-fast bacilli in the smears. A diagnosis of erythema nodosum leprosum (ENL) was made on FNAC. CONCLUSION: The presence of neutrophils in a characteristic milieu of foamy macrophages is seen in lesions of ENL. Such a picture should prompt the cytologist to use a modified Ziehl-Neelsen stain to demonstrate acid-fast bacilli, as ENL can present as an acute episode in patients without a previous diagnosis of leprosy.

Neutrophils isolated from leprosy patients release TNF-alpha and exhibit accelerated apoptosis in vitro.

This study demonstrated that polymorphonuclear neutrophils (PMN) participate in the acute inflammatory response in leprosy as effector cells. Lepromatous patients present intense infiltrate of neutrophils in reactional (ENL) lesions. Circulating PMN of nonreactional patients, healthy donors, and reactional patients were purified and analyzed in vitro. The study confirmed the short lifespan of these cells in culture with progressive changes characteristic of apoptosis. Apoptosis was greatly accelerated in ENL patients as shown by cellular morphology, later confirmed by qualitative and quantitative analysis of fragmented DNA. It was observed that neutrophils stimulated with lipopolysaccharide, Mycobacterium leprae, and lipoarabinomannan secrete interleukin-8 and tumor necrosis factor alpha (TNF-alpha). Thalidomide, a drug known to inhibit TNF-alpha synthesis on monocytes, also exerted an inhibitory effect on TNF-alpha secretion in neutrophils. These data suggest that PMN can participate in the regulation of the immune response in leprosy and can contribute to the amplification of TNF-alpha production at the site of ENL lesion.

Nodular lepromatous leprosy: report of a case diagnosed by FNA.

Lepromatous leprosy can present with skin nodules which can be misdiagnosed as soft tissue tumors or infected cysts. FNA can be diagnostic if unstained, refractile, intracellular mycobacteria are recognized on Romanowsky stained smears. Fite stain for Mycobacterium leprae confirms the diagnosis. Awareness of the differential diagnosis of skin nodules yielding foamy histiocytes on FNA, briefly discussed, should help avoid error.

Rationale for the histological spectrum of tuberculosis. A basis for classification.

There is need to re-appraise the cellular response to Mycobacterium tuberculosis. Histological analysis of 54 untreated patients with established disease demonstrated a continuous spectrum of tissue responses in which six groups correlated with evidence of resistance to bacterial multiplication. A predominance of cases in the two middle groups (82%) signified an immunological equilibrium in middle grade resistant patients that is absent in related diseases such as leprosy and cutaneous leishmaniasis. The dominant feature was necrosis, which increased progressively across the spectrum. Its form varied from minimal fibrinoid change, through fine eosinophilic necrosis, to basophilic necrosis characterized by neutrophil karyorrhexis, and finally to an almost acellular lesion with many bacilli. Cytological differentiation of the granuloma was of subsidiary significance, mature epithelioid cells being found only in high resistant cases. No correlation was found for the number of lymphocytes. This classification is thought to be an accurate reflection of the immune state in relation to antigenic load. It raises a hitherto unconsidered possibility that "caseation", a loosely applied macroscopic term, may embrace immunologically distinct states. The classification of multiple lesions was consistent. Histology offers a promising basis for further immunopathological investigation.

Erythema nodosum leprosum: nature and extent of the cutaneous microvascular alterations.

Skin biopsy specimens from four patients with erythema nodosum leprosum, when examined as Epon-embedded, 1-micron sections, exhibited a necrotizing vasculitis involving capillaries, venules, and small-to-medium arteries and veins. In the superficial dermis, affected venules and capillaries showed endothelial cell enlargement and focal necrosis associated with perivascular infiltrates of lymphocytes. In the deep dermis and subcutaneous tissue, affected venules, arterioles, and arteries exhibited endothelial cell necrosis and matted fibrin in the vessel walls associated with perivascular infiltrates of neutrophils. Throughout the dermis, mononuclear phagocytes with vacuoles containing numerous fragmented organisms were observed. By electron microscopy, electron-dense material resembling immune complexes was observed in the walls of these vessels. These observations support the concept that erythema nodosum leprosum is an immune complex-mediated necrotizing vasculitis involving capillaries, arterioles, arteries, venules, and veins.

Sequential histological study of lepromin reaction.

Skin testing with Dharmendra antigen was performed on 55 patients with TT, BT, BL, and LL types of leprosy and the reaction measured at different intervals from 24 hr to 28 days. At various time intervals, a biopsy specimen was taken from the reaction site. In TT and BT cases, the erythema was maximum at 48 hr; while the induration was maximum at 21 days. The sequence of the histological changes was built up on the observations made from different cases at varying intervals. The quantum of cellular exudate was high in TT and BT cases as compared to BL and LL cases. The cellular distribution showed loose scattering of cells in the LL and BL types and attempts to form tight clusters in the TT and BT cases. Neutrophils were predominant during the first 48 hr, particularly in the LL, BL, and BT types. By 72 hr the cells were mainly lymphocytic. A tendency for the lymphocytes to cluster around nerve twigs was seen in the TT and BT cases. In the early reaction the quantum of exudate correlated both with erythema and induration; while in the late reaction, it correlated with induration only. The intensity of the early lepromin reaction was more in BT than in TT leprosy, while the induration in the late reaction was more in TT than in BT types. The significance of these findings is discussed.

Mycobacterium leprae infection in nude mice: bacteriological and histological responses to primary infection and large inocula.

Previous studies have demonstrated that congenitally athymic, nude mice are highly susceptible to infection with Mycobacterium leprae. In this study, we showed that footpad inoculation of nude mice with different inoculum sizes of M. leprae resulted in exponential growth of bacilli until bacillary numbers reached approximately 10(10) bacilli per footpad. There was dissemination of the infection from approximately 10 months after inoculation. When nude mice were compared with thymectomized and irradiated mice and normal intact mice for the ability to detect growth from large inocula of low viability, nude mice were the most sensitive, permitting the detection of 10(2) viable M. leprae among 10(7) irradiation-killed organisms. There was widespread dissemination of the infection throughout the reticuloendothelial system and the tissues of the cooler body sites from approximately 10 months after inoculation. Histologically, the lesions resembled those seen in lepromatous leprosy, although the bacillary load appeared larger and was similar to that seen in heavily infected tissues of the nine-banded armadillo. An unusual feature was the presence of numerous foci of neutrophil polymorphs in the footpads and liver of infected nude mice.