DC-SIGN receptor is expressed by cells from cutaneous leishmaniasis lesions and differentially binds to Leishmania (Viannia) braziliensis and L. (Leishmania) amazonensis promastigotes.

BACKGROUND: Dendritic cells (DCs) specific intercellular adhesion molecule (ICAM)-3-grabbing non integrin receptor (DC-SIGN) binds to subgenera Leishmania promastigotes mediating its interaction with DC and neutrophils, potentially influencing the infection outcome. OBJECTIVES: In this work, we investigated whether DC-SIGN receptor is expressed in cells from cutaneous leishmaniasis (CL) lesions as well as the in vitro binding pattern of Leishmania (Viannia) braziliensis (Lb) and L. (L.) amazonensis (La) promastigotes. METHODS: DC-SIGN receptor was labeled by immunohistochemistry in cryopreserved CL tissue fragments. In vitro binding assay with CFSE-labeled Lb or La promastigotes and RAJI-transfecting cells expressing DC-SIGN (DC-SIGNPOS) or mock-transfected (DC-SIGNNEG) were monitored by flow cytometry at 2 h, 24 h and 48 h in co-culture. RESULTS: In CL lesion infiltrate, DC-SIGNPOS cells were present in the dermis and near the epidermis. Both Lb and La bind to DC-SIGNPOS cells, while binding to DC-SIGNNEG was low. La showed precocious and higher affinity to DC-SIGNhi population than to DC-SIGNlow, while Lb binding was similar in these populations. CONCLUSION: Our results demonstrate that DC-SIGN receptor is present in L. braziliensis CL lesions and interact with Lb promastigotes. Moreover, the differences in the binding pattern to Lb and La suggest DC-SIGN can influence in a difference way the intake of the parasites at the first hours after Leishmania infection. These results raise the hypothesis that DC-SIGN receptor could participate in the immunopathogenesis of American tegumentary leishmaniasis accounting for the differences in the outcome of the Leishmania spp. infection.

DC-SIGN receptor is expressed by cells from cutaneous leishmaniasis lesions and differentially binds to Leishmania (Viannia) braziliensis and L. (Leishmania) amazonensis promastigotes

BACKGROUND Dendritic cells (DCs) specific intercellular adhesion molecule (ICAM)-3-grabbing non integrin receptor (DC-SIGN) binds to subgenera Leishmania promastigotes mediating its interaction with DC and neutrophils, potentially influencing the infection outcome. OBJECTIVES In this work, we investigated whether DC-SIGN receptor is expressed in cells from cutaneous leishmaniasis (CL) lesions as well as the in vitro binding pattern of Leishmania (Viannia) braziliensis (Lb) and L. (L.) amazonensis (La) promastigotes. METHODS DC-SIGN receptor was labeled by immunohistochemistry in cryopreserved CL tissue fragments. In vitro binding assay with CFSE-labeled Lb or La promastigotes and RAJI-transfecting cells expressing DC-SIGN (DC-SIGNPOS) or mock-transfected (DC-SIGNNEG) were monitored by flow cytometry at 2 h, 24 h and 48 h in co-culture. RESULTS In CL lesion infiltrate, DC-SIGNPOS cells were present in the dermis and near the epidermis. Both Lb and La bind to DC-SIGNPOS cells, while binding to DC-SIGNNEG was low. La showed precocious and higher affinity to DC-SIGNhi population than to DC-SIGNlow, while Lb binding was similar in these populations. CONCLUSION Our results demonstrate that DC-SIGN receptor is present in L. braziliensis CL lesions and interact with Lb promastigotes. Moreover, the differences in the binding pattern to Lb and La suggest DC-SIGN can influence in a difference way the intake of the parasites at the first hours after Leishmania infection. These results raise the hypothesis that DC-SIGN receptor could participate in the immunopathogenesis of American tegumentary leishmaniasis accounting for the differences in the outcome of the Leishmania spp. infection.

Elevated Pentraxin-3 Concentrations in Patients With Leprosy: Potential Biomarker of Erythema Nodosum Leprosum.

Background: Leprosy, the leading infectious cause of disability worldwide, remains a major public health challenge in the most severely affected countries despite the sharp decline in new cases in recent years. The search for biomarkers is essential to achieve a better understanding of the molecular and cellular mechanisms underlying the disease. Methods: Pentraxin-3 (PTX3) analyses of sera from 87 leprosy patients with or without reactions were conducted via enzyme-linked immunosorbent assay. In situ identification of PTX3 in skin lesion was confirmed by quantitative reverse-transcription polymerase chain reaction, immunohistochemistry, and immunofluorescence assays. Results: We found that PTX3 serum levels were higher in multibacillary patients when evaluated before the onset of acute erythema nodosum leprosum (ENL) and persistently elevated during reaction. Thalidomide treatment reduced PTX3 in the serum 7 days after starting treatment. In situ analyses have also demonstrated enhancement of PTX3 in ENL lesions and showed that treatment with thalidomide reduced its expression and the prominent neutrophilic infiltrate, a hallmark of the disease. Conclusions: In summary, our study provides in vivo evidence that PTX3 is enhanced during ENL but not in reversal reaction and provides a new molecular target in ENL pathogenesis.

Type 1 reaction in leprosy: a model for a better understanding of tissue immunity under an immunopathological condition.

Type 1 reaction (T1R) or reversal reaction is the leading cause of physical disabilities and deformities in leprosy. Leprosy patients, even after being considered cured and released from treatment, may suffer from reactional episodes for long periods of time. Early diagnosis is a great challenge for effectively treating and managing T1R. There is an urgent need to identify the most significant biomarkers to prevent recurrent T1R and to differentiate late T1R from relapse. T1R continues to be treated with corticosteroids and complications due to iatrogenic treatment remain frequent. This review aims to provide a framework from which to approach the great challenges that still persist in T1R management and debate key issues in order to reduce the distance between basic research and the clinic.

Effect of apoptotic cell recognition on macrophage polarization and mycobacterial persistence.

Intracellular Mycobacterium leprae infection modifies host macrophage programming, creating a protective niche for bacterial survival. The milieu regulating cellular apoptosis in the tissue plays an important role in defining susceptible and/or resistant phenotypes. A higher density of apoptotic cells has been demonstrated in paucibacillary leprosy lesions than in multibacillary ones. However, the effect of apoptotic cell removal on M. leprae-stimulated cells has yet to be fully elucidated. In this study, we investigated whether apoptotic cell removal (efferocytosis) induces different phenotypes in proinflammatory (Mϕ1) and anti-inflammatory (Mϕ2) macrophages in the presence of M. leprae. We stimulated Mϕ1 and Mϕ2 cells with M. leprae in the presence or absence of apoptotic cells and subsequently evaluated the M. leprae uptake, cell phenotype, and cytokine pattern in the supernatants. In the presence of M. leprae and apoptotic cells, Mϕ1 macrophages changed their phenotype to resemble the Mϕ2 phenotype, displaying increased CD163 and SRA-I expression as well as higher phagocytic capacity. Efferocytosis increased M. leprae survival in Mϕ1 cells, accompanied by reduced interleukin-15 (IL-15) and IL-6 levels and increased transforming growth factor beta (TGF-ß) and IL-10 secretion. Mϕ1 cells primed with M. leprae in the presence of apoptotic cells induced the secretion of Th2 cytokines IL-4 and IL-13 in autologous T cells compared with cultures stimulated with M. leprae or apoptotic cells alone. Efferocytosis did not alter the Mϕ2 cell phenotype or cytokine secretion profile, except for TGF-ß. Based on these data, we suggest that, in paucibacillary leprosy patients, efferocytosis contributes to mycobacterial persistence by increasing the Mϕ2 population and sustaining the infection.

Thalidomide modulates Mycobacterium leprae-induced NF-κB pathway and lower cytokine response.

It is widely accepted that tumor necrosis factor alpha (TNF-α) plays a critical role in the development of tissue and nerve damage in leprosy and during the reactional episodes of acute inflammation. Thalidomide (N-α-phthalimidoglutarimide), a drug used to treat leprosy reaction, modulates immune response, inhibits inflammation and NF-κB activity. Here we investigated whether thalidomide inhibits NF-κB activation induced by Mycobacterium leprae, p38 and ERK1/2 MAPK activation. EMSA and supershift assays were performed to investigate NF-κB activation in response to M. leprae and its modulation following in vitro treatment with thalidomide. Luciferase assay was assayed in transfected THP-1 cells to determine NF-κB transcriptional activity. Flow cytometry and immunofluorescence were used to investigate p65 accumulation in the nucleus. Immunoblotting was used to investigate p38 and ERK1/2 phosphorylation. Following activation of PBMC and monocytes with M. leprae, the formation and nuclear localization of NF-κB complexes composed mainly of p65/p50 and p50/p50 dimers was observed. Induction of NF-κB activation and DNA binding activity was inhibited by thalidomide. The drug also reduced M. leprae-induced TNF-α production and inhibited p38 and ERK1/2 activation. Definition of the activation mechanisms in cells stimulated with M. leprae can lead to the development of new therapy applications to modulate NF-κB activation and to control the inflammatory manifestations due to enhanced TNF-α response as observed in leprosy and in leprosy reactions.

Mycobacterium leprae-host-cell interactions and genetic determinants in leprosy: an overview.

Leprosy, also known as Hansen's disease, is a chronic infectious disease caused by Mycobacterium leprae in which susceptibility to the mycobacteria and its clinical manifestations are attributed to the host immune response. Even though leprosy prevalence has decreased dramatically, the high number of new cases indicates active transmission. Owing to its singular features, M. leprae infection is an attractive model for investigating the regulation of human immune responses to pathogen-induced disease. Leprosy is one of the most common causes of nontraumatic peripheral neuropathy worldwide. The proportion of patients with disabilities is affected by the type of leprosy and delay in diagnosis. This article briefly reviews the clinical features as well as the immunopathological mechanisms related to the establishment of the different polar forms of leprosy, the mechanisms related to M. leprae-host cell interactions and prophylaxis and diagnosis of this complex disease. Host genetic factors are summarized and the impact of the development of interventions that prevent, reverse or limit leprosy-related nerve impairments are discussed.

HIV-M. leprae interaction: can HAART modify the course of leprosy?

It has been speculated that, as seen in tuberculosis, human immunodeficiency virus (HIV) and Mycobacterium leprae (M. leprae) co-infection may exacerbate the pathogenesis of leprosy lesions and/or lead to increased susceptibility to leprosy. However, to date, HIV infection has not appeared to increase susceptibility to leprosy. In contrast, initiation of antiretroviral treatment (ART) has been reported to be associated with anecdotal activation of M. leprae infection and exacerbation of existing leprosy lesions. To determine whether ART is associated with worsening of the manifestations of leprosy, a cohort of leprosy patients recruited between 1996 and 2006 at the Oswaldo Cruz Foundation (FIOCRUZ) Leprosy Outpatient Clinic in Rio de Janeiro, Brazil, was studied longitudinally. ART treatment of HIV/leprosy co-infection was associated with the tuberculoid type, paucibacillary disease, and lower bacillary loads. CD4 lymphocyte counts were higher among HIV/leprosy patients at the time of leprosy diagnosis, while viral loads were lower compared with the time of HIV diagnosis. The conclusion was that ART and immune reconstitution were critical factors driving the development and/or clinical appearance of leprosy lesions.

Ninjurin 1 asp110ala single nucleotide polymorphism is associated with protection in leprosy nerve damage.

Leprosy is the major cause of non-traumatic neuropathy. Herein, we investigated the role of ninjurin 1, an adhesion molecule involved in nerve regeneration in leprosy. Our results demonstrated that M. leprae stimulates in vitro up-regulation of ninjurin mRNA in cultured Schwann and blood cells as well as in vivo mRNA and protein expression in leprosy nerve biopsies. A polymorphism (asp110ala) was investigated in a case-control study (1123 individuals) and no association was found with leprosy per se or with disseminated forms. Nevertheless, ala110 was associated with functional nerve impairment (OR=2.42; p=0.02 for ala/ala) and with lower mRNA levels. Our data suggests that asp110ala could be a valuable genetic marker of nerve damage in leprosy.

Experimental mycobacterium leprae infection in BALB/c Mice: effect of BCG administration on TNF-a production and granuloma development

In the present study, the experimental model of Mycobacterium leprae infection in the foot pads of BALB/c mice was used to investigate the effects of BCG administration on tumor necrosis factor-alpha (TNF-alpha) production and granuloma development. It was observed that mice intravenously infected with BCG 7 months after M. leprae inoculation into the foot pads presented a more effective mycobacteria clearance, revealed by a significant reduction of BCG-colony forming units in the spleen and by the reduction of acid-fast bacilli (AFB) in the foot pads. BCG infection at the peak of M. leprae infection also modulated the granulomatous response to M. leprae by converting mononuclear granulomas into an epithelioid-cell granuloma. Furthermore, lower TNF-alpha serum levels were detected in M. leprae-infected mice when compared to mice infected with M. leprae + BCG. An analysis of the TNF-alpha gene expression in the spleen by semiquantitative reverse transcription-polymerase chain reactions (RT-PCR) demonstrated that co-infection with BCG induced an earlier expression of TNF-alpha mRNA than in M. leprae-infected mice. The numbers of TNF-alpha-positive cells and apoptotic cells were also enhanced in epithelioid versus non-epithelioid granulomas. As a whole, the data suggest that co-infection of M. leprae-infected mice with BCG modulates TNF-alpha synthesis which, in turn, leads to induction of protective epithelioid granuloma formation in the foot pads and subsequent mycobacterial clearance. Macrophage differentiation into epithelioid cells, in association with the enhancement of TNF-alpha production at the granuloma site, may represent a triggering signal that induced apoptosis in these cells, leading to mycobacterial elimination. Moreover, the rate of apoptosis in epithelioid granulomas may well be related to the extent of immunopathologically mediated tissue damage.

Immunological responsiveness to M. leprae and BCG antigens in 98 leprosy patients and their household contacts

The cellular immune response to M. leprae and BCG antigens was evaluated in 98 leprosy patients and 143 household contacts lacking clinical manifestation of the disease. The proliferative responses and release of Interferon-gamma by peripheral blood mononuclear cells were assessed and both patients and contacts were classified as low or high responders to M. leprae. The high responder contacts constitued 54.8% of the population analyzed, a three times higher proportion when compared to the controls, indicating the possible existence of active infection among them. The correlation coefficient between the immunological response to M. leprae and BCG was found to be higher within the contact group than in the patients, suggesting that cross-reactivity defense mechanisms against mycobacteria exist even before the onset of clinical detectable disease

Isolation and functional characterization of mononuclear phagocytes from human lepromatous lesions

Células inflamatórias presentes em lesöes Virchowianas humanas foram isoladas do tecido por um processo de digestäo enzimática. Elas foram mantidas em cultura por cerca de 5 dias e suas características morfológicas citoquímicas e funcionais foram descritas

Caracterizaçäo morfológica e funcional de células aderentes de baço de camundongo / Morphological and functional characterization of adherent splenic cells of mice

A separaçäo, caracterizaçäo e ensaio funcional das células inflamatórias presentes no local de lesäo têm se tornado imperiosos no estudo de diversas doenças. Através da utilizaçäo de métodos histoquímicos para esterase e fosfatase ácida, bem como do Teste de Fagocitose e da coloraçäo pelo Giemsa, realizados nas células esplénicas de dez camundongos, foi possível se caracterizar bem os componentes do Sistema Fagocítico Mononuclear e distinguir os outros tipos de células presentes, além de permitir a quantificaçäo diferencial das mesmas