Cytokine patterns at the site of mycobacterial infection

Different profiles of chemokines, cytokines and cell growth factors in plasma samples from patients with leprosy, leprosy reactions and households contacts

BACKGROUND

Leprosy is a highly neglected disease that is considered a serious public health problem in many countries. This illness is characterised by a variety of clinical and histopathological manifestations that are related to the patient immune response.

OBJECTIVES

This work aimed evaluate the profile of circulating immune mediators in the plasma from patients classified clinically as paucibacillary (PB), multibacillary (MB), households contacts (HHC), type1 leprosy reaction (T1R), type2 leprosy reaction (T2R) and control individuals without medical history of leprosy (CTL).

METHODS

To assessment of the plasma immune mediators was used multiplex microbeads immunoassay "Luminex".

FINDINGS

The results showed that patients (PB) had a regulatory-biased profile, while MB revealed a pro-inflammatory trend of highly expressed biomarkers. HHC display conspicuously increased levels in the plasma of the chemokines (CCL2, CCL3, CCL4, CCL5 and CXCL8), pro-inflammatory cytokines (IFN-γ,TNF and IL-1β), modulating cytokines (IL-9 and IL-1Ra) and growth factors (PDGF, G-CSF and IL-2). Interestingly, HHC displayed superior production of IFN-γ as compared to other leprosy groups, indicating a putative protective role for this cytokine during chronic Mycobacterium leprae exposure.

MAIN CONCLUSION

Further investigations are currently underway to elucidate the potential of these mediators as biomarkers applicable to the diagnosis/prognosis of leprosy and also T1R and T2R leprosy reactions.

Th17 Cells and Cytokines in Leprosy: Understanding the Immune Response and Polarization

While there are conflicting data concerning interleukin (IL)-17 levels in the serum of patients with leprosy compared with those in healthy controls, higher levels have been more evident in the tuberculoid clinical form of leprosy and type 1 reactions. This review aimed to highlight the role of Th17 cells and their cytokines in leprosy. Cytokines such as IL-1β and IL-23 induce Th17, while transforming growth factor beta and IL-10 inhibit Th17, indicating that the balance between Th17 and regulatory T cells is crucial for leprosy polarization. However, more comprehensive paired studies are required to better elucidate the role of Th17 cells in leprosy.

Host Immune-Metabolic Adaptations Upon Mycobacterial Infections and Associated Co-Morbidities

Mycobacterial diseases are a major public health challenge. Their causative agents include, in order of impact, members of the Mycobacterium tuberculosis complex (causing tuberculosis), Mycobacterium leprae (causing leprosy), and non-tuberculous mycobacterial pathogens including Mycobacterium ulcerans. Macrophages are mycobacterial targets and they play an essential role in the host immune response to mycobacteria. This review aims to provide a comprehensive understanding of the immune-metabolic adaptations of the macrophage to mycobacterial infections. This metabolic rewiring involves changes in glycolysis and oxidative metabolism, as well as in the use of fatty acids and that of metals such as iron, zinc and copper. The macrophage metabolic adaptations result in changes in intracellular metabolites, which can post-translationally modify proteins including histones, with potential for shaping the epigenetic landscape. This review will also cover how critical tuberculosis co-morbidities such as smoking, diabetes and HIV infection shape host metabolic responses and impact disease outcome. Finally, we will explore how the immune-metabolic knowledge gained in the last decades can be harnessed towards the design of novel diagnostic and therapeutic tools, as well as vaccines.

The emerging role of exosomal miRNAs as a diagnostic and therapeutic biomarker in Mycobacterium tuberculosis infection

Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb), has been the world's driving fatal bacterial contagious disease globally. It continues a public health emergency, and around one-third of the global community has been affected by latent TB infection (LTBI). This is mostly due to the difficulty in diagnosing and treating patients with TB and LTBI. Exosomes are nanovesicles (40-100 nm) released from different cell types, containing proteins, lipids, mRNA, and miRNA, and they allow the transfer of one's cargo to other cells. The functional and diagnostic potential of exosomal miRNAs has been demonstrated in bacterial infections, including TB. Besides, it has been recognized that cells infected by intracellular pathogens such as Mtb can be secreting an exosome, which is implicated in the infection's fate. Exosomes, therefore, open a unique viewpoint on the investigative process of TB pathogenicity. This study explores the possible function of exosomal miRNAs as a diagnostic biomarker. Moreover, we include the latest data on the pathogenic and therapeutic role of exosomal miRNAs in TB.

Broadly reactive human CD4+ T cells against Enterobacteriaceae are found in the naïve repertoire and are clonally expanded in the memory repertoire

Enterobacteriaceae are a large family of Gram-negative bacteria that includes both commensals and opportunistic pathogens. The latter can cause severe nosocomial infections, with outbreaks of multi-antibiotics resistant strains, thus being a major public health threat. In this study, we report that Enterobacteriaceae-reactive memory Th cells were highly enriched in a CCR6+ CXCR3+ Th1*/17 cell subset and produced IFN-γ, IL-17A, and IL-22. This T cell subset was severely reduced in septic patients with K. pneumoniae bloodstream infection who also selectively lacked circulating K. pneumonie-reactive T cells. By combining heterologous antigenic stimulation, single cell cloning and TCR Vβ sequencing, we demonstrate that a large fraction of memory Th cell clones was broadly cross-reactive to several Enterobacteriaceae species. These cross-reactive Th cell clones were expanded in vivo and a large fraction of them recognized the conserved outer membrane protein A antigen. Interestingly, Enterobacteriaceae broadly cross-reactive T cells were also prominent among in vitro primed naïve T cells. Collectively, these data point to the existence of immunodominant T cell epitopes shared among different Enterobacteriaceae species and targeted by cross-reactive T cells that are readily found in the pre-immune repertoire and are clonally expanded in the memory repertoire.

Targeting Autophagy as a Strategy for Developing New Vaccines and Host-Directed Therapeutics Against Mycobacteria

Mycobacterial disease is an immense burden worldwide. This disease group includes tuberculosis, leprosy (Hansen's disease), Buruli Ulcer, and non-tuberculous mycobacterial (NTM) disease. The burden of NTM disease, both pulmonary and ulcerative, is drastically escalating globally, especially in developed countries such as America and Australia. Mycobacteria's ability to inhibit or evade the host immune system has contributed significantly to its continued prevalence. Pre-clinical studies have highlighted promising candidates that enhance endogenous pathways and/or limit destructive host responses. Autophagy is a cell-autonomous host defense mechanism by which intracytoplasmic cargos can be delivered and then destroyed in lysosomes. Previous studies have reported that autophagy-activating agents, small molecules, and autophagy-activating vaccines may be beneficial in restricting intracellular mycobacterial infection, even with multidrug-resistant strains. This review will examine how mycobacteria evade autophagy and discusses how autophagy could be exploited to design novel TB treatment strategies, such as host-directed therapeutics and vaccines, against Mycobacterium tuberculosis and NTMs.

Case Report: Microglia Composition and Immune Response in an Immunocompetent Patient With an Intracranial Syphilitic Gumma

The pathogenesis of intracranial syphilitic gummas remains poorly understood. Microglia are generally considered to be the main cell type of the innate immune system in the brain. Determination of the composition of infiltrating microglia of patients with typical intracranial syphilitic gummas may contribute to the understanding of the pathological process. We report a case of an intracranial syphilitic gumma who presented with right upper limb weakness. The histological analysis showed the presence of Treponema pallidum and infiltration with histiocytes. Immunostaining indicated that cells were predominantly the M2a and M2c, which were Arg-1⁺ and IL-10⁺. These findings suggest that there is an increased number of M2a/M2c microglia in intracranial syphilitic gummas, which may be part of the immune escape mechanisms triggered by Treponema pallidum.

Simultaneous analysis of multiple T helper subsets in leprosy reveals distinct patterns of Th1, Th2, Th17 and Tregs markers expression in clinical forms and reactional events

Leprosy is a chronic infectious disease caused by Mycobacterium leprae. Previous studies have demonstrated that the difference among clinical forms of leprosy can be associated with the immune response of patients, mainly by T helper (Th) and regulatory T cells (Tregs). Then, aiming at clarifying the immune response, the expression of cytokines related to Th1, Th2, Th17 and Tregs profiles were evaluated by qPCR in 87 skin biopsies from leprosy patients. Additionally, cytokines and anti-PGL-1 antibodies were determined in serum by ELISA. The results showed that the expression of various targets (mRNA) related to Th1, Th2, Th17 and Tregs were significantly modulated in leprosy when compared with healthy individuals, suggesting the presence of a mixed profile. In addition, the targets related to Th1 predominated in the tuberculoid pole and side and Th2 and Tregs predominated in the lepromatous pole and side; however, Th17 targets showed a mixed profile. Concerning reactional events, Tregs markers were decreased and IL-15 was increased in reversal reaction and IL-17F, CCL20 and IL-8 in erythema nodosum leprosum, when compared with the respective non-reactional leprosy patients. Additionally, ELISA analysis demonstrated that IL-22, IL-6, IL-10 and anti-PGL-1 antibody levels were significantly higher in the serum of patients when compared with healthy individuals, and IL-10 and anti-PGL-1 antibodies were also increased in the lepromatous pole and side. Together, these results indicate that Th1, Th2 and Th17 are involved in the determination of clinical forms of leprosy and suggest that decreased Tregs activity may be involved in the pathogenesis of reactional events.

Cytokines as biomarkers to monitoring the impact of multidrug therapy in immune response of leprosy patients

Leprosy or Hansen's disease is a chronic infectious disease of the skin and nerves, caused by the intracellular bacilli Mycobacterium leprae. It is characterized by a spectrum of clinical forms depending on the host's immune response to M. leprae. Patients with tuberculoid (TT) leprosy have strong cell-mediated immunity (CMI) with elimination of the bacilli, whereas patients with lepromatous (LL) leprosy exhibit defective CMI to M. leprae. Despite advances in the understanding of the pathogenesis of leprosy and the development of new therapeutic strategies, there is a need for the identification of biomarkers which be used for early diagnosis and to discrimination between different forms of the disease, as prognostic markers. Here, we analyzed the serum levels of IL-1β, IL-6, IL-8, IL-10, IL-12p70, IL-13, IL-17A, IFN-γ and TNF in order to address the contribution of these cytokines in late phase of M. leprae infection, and the impact of multidrug therapy (MDT). Our results demonstrated that patients of LL group presented higher expression of serum levels of inflammatory cytokines before MDT, while TT patients presented a balance between inflammatory and regulatory cytokines. MDT changes the profile of serum cytokines in M. leprae infected patients, as evidenced by the cytokine network, especially in TT patients. LL patients displayed a multifaceted cytokine system characterized by strong connecting axes involving inflammatory/regulatory molecules, while TT patients showed low involvement of regulatory cytokines in network overall. Cytokines can be identified as good biomarkers of the impact of MDT on the immune system and the effectiveness of treatment.

Autophagy Is an Innate Mechanism Associated with Leprosy Polarization

Leprosy is a chronic infectious disease that may present different clinical forms according to the immune response of the host. Levels of IFN-γ are significantly raised in paucibacillary tuberculoid (T-lep) when compared with multibacillary lepromatous (L-lep) patients. IFN-γ primes macrophages for inflammatory activation and induces the autophagy antimicrobial mechanism. The involvement of autophagy in the immune response against Mycobacterium leprae remains unexplored. Here, we demonstrated by different autophagic assays that LC3-positive autophagosomes were predominantly observed in T-lep when compared with L-lep lesions and skin-derived macrophages. Accumulation of the autophagic receptors SQSTM1/p62 and NBR1, expression of lysosomal antimicrobial peptides and colocalization analysis of autolysosomes revealed an impairment of the autophagic flux in L-lep cells, which was restored by IFN-γ or rapamycin treatment. Autophagy PCR array gene-expression analysis revealed a significantly upregulation of autophagy genes (BECN1, GPSM3, ATG14, APOL1, and TPR) in T-lep cells. Furthermore, an upregulation of autophagy genes (TPR, GFI1B and GNAI3) as well as LC3 levels was observed in cells of L-lep patients that developed type 1 reaction (T1R) episodes, an acute inflammatory condition associated with increased IFN-γ levels. Finally, we observed increased BCL2 expression in L-lep cells that could be responsible for the blockage of BECN1-mediated autophagy. In addition, in vitro studies demonstrated that dead, but not live M. leprae can induce autophagy in primary and lineage human monocytes, and that live mycobacteria can reduce the autophagy activation triggered by dead mycobacteria, suggesting that M. leprae may hamper the autophagic machinery as an immune escape mechanism. Together, these results indicate that autophagy is an important innate mechanism associated with the M. leprae control in skin macrophages.

Leprosy is an interesting model to study immune responses in humans due to the dichotomy observed among the poles of the disease. While in the self-limited tuberculoid form (T-lep) there are high systemic levels of the cytokine IFN-γ, in the clinically progressive lepromatous form (L-lep) low IFN-γ levels are found. IFN-γ activates an antimicrobial mechanism called autophagy, which has been implicated in control of Mycobacterium tuberculosis infection. However, the role played by autophagy in the immunopathogenesis of leprosy remains unknown. Here we show that autophagy was differentially regulated in T-lep and L-lep patients. In T-lep skin lesion cells autophagy contributes for bacilli control, whereas in L-lep cells the BCL2-mediated block of autophagy promotes the mycobacterial persistence. We also observed that IFN-γ may counteract the inhibition of autophagy triggered by M. leprae infection in L-lep macrophages. In addition, the levels of autophagy were restored in L-lep patients who developed the reversal reaction, an inflammatory state associated with augmented IFN-γ, which is the most important cause of nerve damage and deformities in leprosy. These findings suggest that the modulation of autophagy has the potential to be useful in the treatment of the disease, and provides new insights to prevent leprosy reactional episodes.

Leprosy in Denmark 1980-2010: a review of 15 cases

Background

Leprosy, caused by Mycobacterium leprae, is a chronic and progressive granulomatous disease affecting mainly the skin and the peripheral nervous system. If left unrecognized, the infection can lead to permanent nerve damage and disability. The clinical presentation depends on the immune response of the patient and can result in a wide spectrum of symptoms. Leprosy is a rare encounter in Scandinavia but remains endemic in some parts of the world, with some areas reporting an increasing incidence. We performed a retrospective record review of leprosy cases in Denmark from 1980 to 2010 with the purpose of presenting the most common geographical, demographic and clinical findings and to discuss the diagnostic and therapeutic challenges of patients with leprosy.

Case presentation

In total 15 cases were reviewed. The majority (87 %) of leprosy patients in Denmark were born in South- and Southeast Asia, and were presumed to have contracted the infection in their countries of origin. Patients were predominately young males (mean age: 28.6 years). Anaesthetic skin lesion with or without nerve enlargement were the most common clinical presentations (73 %). Immunological leprosy reactions were seen in 40 % of the cases. Diagnoses were based on clinical findings and skin biopsies. Treatment length varied but all patients received multidrug regimens.

Conclusion

Leprosy should be kept in mind when encountering patients with suspicious skin lesions originating from leprosy endemic areas or with history of travel or work in the tropics. Due to the long incubation period with symptoms presenting long after immigration or return, clinicians often do not have the diagnosis in mind. The wide spectrum of symptoms and immunological reactions further complicates the diagnostic process. Treatment of leprosy and the complicated immunological reactions, which frequently accompanies the infection, should be performed in collaboration with a specialist.

Electronic supplementary material

The online version of this article (doi:10.1186/s13104-015-1768-6) contains supplementary material, which is available to authorized users.

Langerhans cells (CD1a and CD207), dermal dendrocytes (FXIIIa) and plasmacytoid dendritic cells (CD123) in skin lesions of leprosy patients

The clinical course of infection with Mycobacterium leprae varies widely and depends on the pattern of the host immune response. Dendritic cells play an important role in the activation of the innate and adaptive immune system and seem to be essential for the development of the disease. To analyze the presence of epidermal dendritic cells (CD1a and CD207), plasmacytoid dendritic cells (CD123) and dermal dendrocytes (factor XIIIa) in lesion fragments of leprosy patients, skin samples from 30 patients were studied. These samples were submitted to immunohistochemistry against CD1a, CD207, FXIIIa, and CD123. The results showed a larger number of Langerhans cells, detected with the CD1a or CD207 marker, dermal dendrocytes and plasmacytoid dendritic cells in patients with the tuberculoid form. A positive correlation was observed between the Langerhans cell markers CD1a and CD207 in both the tuberculoid and lepromatous forms, and between Langerhans cells and dermal dendrocytes in samples with the tuberculoid form. The present results indicate the existence of a larger number of dendritic cells in patients at the resistant pole of the disease (tuberculoid) and suggest that the different dendritic cells studied play a role, favoring an efficient immune response against infection with M. leprae.

Increased ferroportin-1 expression and rapid splenic iron loss occur with anemia caused by Salmonella enterica Serovar Typhimurium infection in mice

The Gram-negative intracellular bacterium Salmonella enterica serovar Typhimurium causes persistent systemic inflammatory disease in immunocompetent mice. Following oral inoculation with S. Typhimurium, mice develop a hematopathological syndrome akin to typhoid fever with splenomegaly, microcytic anemia, extramedullary erythropoiesis, and increased hemophagocytic macrophages in the bone marrow, liver, and spleen. Additionally, there is marked loss of iron from the spleen, an unanticipated result, given the iron sequestration reported in anemia of inflammatory disease. To establish why tissue iron does not accumulate, we evaluated multiple measures of pathology for 4 weeks following oral infection in mice. We demonstrate a quantitative decrease in splenic iron following infection despite increased numbers of splenic phagocytes. Infected mice have increased duodenal expression of the iron exporter ferroportin-1, consistent with increased uptake of dietary iron. Liver and splenic macrophages also express high levels of ferroportin-1. These observations indicate that splenic and hepatic macrophages export iron during S. Typhimurium infection, in contrast to macrophage iron sequestration observed in anemia of inflammatory disease. Tissue macrophage export of iron occurs concurrent with high serum concentrations of interferon gamma (IFN-γ) and interleukin 12 (IL-12). In individual mice, high concentrations of both proinflammatory (tumor necrosis factor alpha [TNF-α]) and anti-inflammatory (IL-10) cytokines in serum correlate with increased tissue bacterial loads throughout 4 weeks of infection. These in vivo observations are consistent with previous cell culture studies and suggest that the relocation of iron from tissue macrophages during infection may contribute to anemia and also to host survival of acute S. Typhimurium infection.

Relationship between growth factors and its implication in the pathogenesis of leprosy

Leprosy is a chronic infectious disease caused by Mycobacterium leprae which affects the skin and peripheral nervous system. The immune response of the host determines the clinical course of the disease. The tuberculoid form is the result of high cell-mediated immunity characterized by a Th1 response, whereas the lepromatous form is characterized by low cell-mediated immunity and a Th2 humoral response. The neural damage established produces marked changes in the expression of growth factors such as nerve growth factor (NGF) and its receptors (NGF-R). The expression of NGF, associated with the expression of Th1 and Th2 cytokines, might be involved in the tissue damage caused by the bacillus. Therefore, the objective of this study was to correlate the immunoexpression patterns of NGF and NGF-R in the different clinical forms of leprosy, and to associate the findings with the in situ expression of TGF-β and clinical classification of the disease. TGF-β, NGF and NGF-R immunoexpression was analyzed by immunohistochemistry in paraffin-embedded material. Most patients were males with a mean age of 40.7 years. TGF-β levels were significantly higher in the lepromatous forms. No significant difference in the immunoexpression of NGF or NGF-R was observed between the clinical forms, but expression tended to be higher at the lepromatous pole. There was a significant positive correlation between NGF and NGF-R in the different clinical forms of leprosy. A significant positive correlation was observed between NGF, NGF-R and TGF-β. It can be concluded that, even existing evidence on the role of these molecules in the clinical spectrum of leprosy.

Leprosy: review of the epidemiological, clinical, and etiopathogenic aspects - part 1

Leprosy is caused by Mycobacterium leprae and has been known since biblical times. It is still endemic in many regions of the world and a public health problem in Brazil. The prevalence rate in 2011 reached 1.54 cases per 10,000 inhabitants in Brazil. The mechanism of transmission of leprosy consists of prolonged close contact between susceptible and genetically predisposed individuals and untreated multibacillary patients. Transmission occurs through inhalation of bacilli present in upper airway secretion. The nasal mucosa is the main entry or exit route of M. leprae. The deeper understanding of the structural and biological characteristics of M. leprae, the sequencing of its genome, along with the advances in understanding the mechanisms of host immune response against the bacilli, dependent on genetic susceptibility, have contributed to the understanding of the pathogenesis, variations in the clinical characteristics, and progression of the disease. This article aims to update dermatologist on epidemiological, clinical, and etiopathogenic leprosy aspects.

Role of CD8(+) T cells in triggering reversal reaction in HIV/leprosy patients

It has been reported that the initiation of highly active anti-retroviral therapy (HAART) is associated with the development of reversal reaction (RR) in co-infected HIV/leprosy patients. Nevertheless, the impact of HIV and HAART on the cellular immune response to Mycobacterium leprae (ML) remains unknown. In the present study, we observed that ex vivo peripheral blood mononuclear cells (PBMCs) of both RR and RR/HIV patients presented increased percentages of activated CD4(+) T cells when compared with the healthy individuals (HC) group. The frequency of CD8(+)  CD38(+) cells increased in the PBMCs of RR/HIV patients but not in RR patients when compared with the HC group. Both RR and RR/HIV skin lesion cells presented similar percentages of activated CD4(+) cells, but the numbers of activated CD8(+) cells were higher in RR/HIV in comparison to the RR group. The frequency of interferon-γ-producing cells was high in response to ML regardless of HIV co-infection. In ML-stimulated cells, there was an increase in central memory CD4(+) T-cell frequencies in the RR and RR/HIV groups, but an increase in central memory CD8(+) T-cell frequency was only observed in the RR/HIV group. ML increased granzyme B(+) effector memory CD8(+) T-cell frequencies in the RR/HIV PBMCs, but not in the HC and RR groups. Our data suggest that the increased expression of effector memory CD8(+) T cells, together with greater perforin/granzyme B production, could be an additional mechanism leading to the advent of RR in co-infected patients. Moreoever, this increased expression may explain the severity of RR occurring in these patients.

Clinical and immunological evaluation after BCG-id vaccine in leprosy patients in a 5-year follow-up study

INTRODUCTION

The use of bacillus Calmette-Guérin (BCG) has long been considered a stimulus for immune reactivity in leprosy household contacts. Probably, the combination of multidrug therapy with BCG could facilitate the clearance of leprosy bacilli in the host, reduce relapse rates, and shorten the duration of skin-smear positivity.

METHODS

To investigate the mechanism of action of BCG, a study involving 19 leprosy patients, eleven multibacillary (MB) and eight paucibacillary, was performed to assess the in vitro production of interleukin (IL)-10, interferon (IFN)-γ, tumor necrosis factor (TNF)-α, IL-6, and IL-17 in the supernatant of peripheral blood mononuclear cells, before and 30 days after inoculation with BCG intradermally (BCG-id). Peripheral blood mononuclear cells isolated by Ficoll-Hypaque gradient were cultivated with Concanavalin-A (Con-A), lipopolysccharides (LPS), or BCG. The supernatant was collected for ELISA quantification of cytokines. The immunohistochemistry of IFN-γ, IL-1, IL-10, IL-12, transforming growth factor (TGF)-β, and TNF-α was carried out in biopsies of skin lesions of leprosy patients before and 30 days after inoculation of BCG-id. These patients were followed up for 5 years to assess the therapeutic response to multidrug therapy, the occurrence of leprosy reactions, and the results of bacterial index and anti-PGL-1 serology after the end of treatment.

RESULTS

The results showed increased production of cytokines after BCG-id administration in MB and paucibacillary leprosy patients. There was statistically higher levels of TNF-α (P = 0.017) in MB patients and of IL-17 (P = 0.008) and IFN-γ (P = 0.037) in paucibacillary patients. Immunohistochemical staining, especially for TNF-α, was more intense in biopsies of MB leprosy patients taken after BCG-id administration, probably for induction of innate human immunity. The clinical evaluation suggests that BCG-id is able to induce a more effective therapeutic response, with reduction of the number and the intensity of leprosy reactions.

CONCLUSION

These results suggest that BCG-id induces activation of the initial phase of immunocellular activity: innate human immunity (increase in TNF-α, IL-12 and macrophage activation). Therefore, we conclude that the use of BCG-id could be indicated as an adjuvant to multidrug therapy in treatment of leprosy patients.

New Aspects in Immunopathology of Mycobacterium tuberculosis

Our understanding of tuberculosis (TB) pathology and immunology has become extensively deeper and more refined since the identification of Mycobacterium tuberculosis (MTB) as the etiologic agent of disease by Dr. Robert Koch in 1882. A great challenge in chronic disease is to understand the complexities, mechanisms, and consequences of host interactions with pathogens. TB, caused by MTB, is a major health problem in world, with 10 million new cases diagnosed each year. Innate immunity is shown playing an important role in the host defense against the MTB, and the first step in this process is recognition of MTB by cells of the innate immune system. Several classes of pattern recognition receptors (PPRs) are involved in the recognition of MTB, including toll-like receptors (TLRs), C-type lectin receptors (CLRs), and nod-like receptors (NLRs). Among the TLR family, TLR1, TLR2, TLR4, and TLR9 and their down streams, proteins play the most prominent roles in the initiation of the immune response against MTB. Beside of TLRs signaling, recently the activation of inflammasome pathway in the pathogenesis of TB much appreciated. Knowledge about these signaling pathways is crucial for understanding the pathophysiology of TB, on one hand, and for the development of novel strategies of vaccination and treatment such as immunotherapy on the other. Given the critical role of TLRs/inflammasome signaling in innate immunity and initiation of the appropriate adaptive response, the regulation of these pathways is likely to be an important determinant of the clinical outcome of MTB infection. In this review paper we focused on the immune response, which is the recognition of MTB by inflammatory innate immune cells following infection.

Leprosy susceptibility: genetic variations regulate innate and adaptive immunity, and disease outcome

The past few years have been very productive concerning the identification of genes associated with leprosy. Candidate gene strategies using both case-control and family-based designs, as well as large-scale approaches such as linkage and gene-expression genomic scans and, more recently, genome-wide association studies, have refined and enriched the list of genes highlighting the most important innate and adaptive immune pathways associated with leprosy susceptibility or resistance. During the early events of host-pathogen interaction identified genes are involved in pattern recognition receptors, and mycobacterial uptake (TLRs, NOD2 and MRC1), which modulate autophagy. Another gene, LTA4H, which regulates the levels of lipoxin A4 and possibly interacts with lipid droplet-related events, also plays a role in the early immune responses to Mycobacterium leprae. Together, the activation of these pathways regulates cellular metabolism upon infection, activating cytokine production through NF-κB and vitamin D-vitamin D receptor pathways, while PARK2 and LRRK2 participate in the regulation of host-cell apoptosis. Concomitantly, genes triggered to form and maintain granulomas (TNF, LTA and IFNG) and genes involved in activating and differentiating T-helper cells (HLA, IL10, as well as the TNF/LTA axis and the IFNG/IL12 axis) bridge immunological regulation towards adaptive immunity. Subtle variations in these genes, mostly single nucleotide polymorphisms, alter the risk of developing the disease or the severity of leprosy. Knowing these genes and their role will ultimately lead to better strategies for leprosy prevention, treatment and early diagnosis. Finally, the same genes associated with leprosy were also associated with autoimmune (Crohn's disease, rheumathoid arthritis, psoriasis) or neurodegenerative diseases (Parkinson's and Alzheimer's). Thus, information retrieved using leprosy as a model could be valuable to understanding the pathogenesis of other complex diseases.

Morphine withdrawal stress modulates lipopolysaccharide-induced interleukin 12 p40 (IL-12p40) expression by activating extracellular signal-regulated kinase 1/2, which is further potentiated by glucocorticoids

Withdrawal stress is a common occurrence in opioid users, yet very few studies have examined the effects of morphine withdrawal (MW) on immune functioning or the role of glucocorticoids in MW-induced immunomodulation. This study investigated for the first time the role of glucocorticoids in MW modulation of LPS-induced IL-12p40, a key cytokine playing a pivotal role in immunoprotection. Using WT and μ-opioid receptor knock-out mice, we show that MW in vivo significantly attenuated LPS-induced IL-12p40 mRNA and protein expression. The role of glucocorticoids in MW modulation of IL-12p40 was investigated using a murine macrophage cell line, CRL2019, in an in vitro MW model. Interestingly, MW alone in the absence of glucocorticoids resulted in a significant reduction in IL-12p40 promoter activity and mRNA and protein expression. EMSA revealed a concurrent decrease in consensus binding to transcription factors NFκB, Activator Protein-1, and CCAAT/enhancer-binding protein and Western blot analysis demonstrated a significant activation of LPS-induced ERK1/2 phosphorylation. Interestingly, although glucocorticoid treatment alone also modulated these transcription factors and ERK1/2 activation, the addition of glucocorticoids to MW samples resulted in a greater than additive reduction in the transcription factors and significant hyperactivation of LPS-induced ERK1/2 phosphorylation. ERK inhibitors reversed MW and MW plus corticosterone inhibition of LPS-induced IL-12p40. The potentiating effects of glucocorticoids were non-genomic because nuclear translocation of glucocorticoid receptor was not significantly different between MW and corticosterone treatment. This study demonstrates for the first time that MW and glucocorticoids independently modulate IL-12p40 production through a mechanism involving ERK1/2 hyperactivation and that glucocorticoids can significantly augment MW-induced inhibition of IL-12p40.

Eosinophilia and biotoxin exposure in bottlenose dolphins (Tursiops truncatus) from a coastal area impacted by repeated mortality events

Bottlenose dolphins (Tursiops truncatus) inhabiting coastal waters in the northern Gulf of Mexico have been impacted by recurrent unusual mortality events over the past few decades. Several of these mortality events along the Florida panhandle have been tentatively attributed to poisoning from brevetoxin produced by the dinoflagellate Karenia brevis. While dolphins in other regions of the Florida coast are often exposed to K. brevis blooms, large-scale dolphin mortality events are relatively rare and the frequency and magnitude of die-offs along the Panhandle raise concern for the apparent vulnerability of dolphins in this region. We report results from dolphin health assessments conducted near St. Joseph Bay, Florida, an area impacted by 3 unusual die-offs within a 7-year time span. An eosinophilia syndrome, manifested as an elevated blood eosinophil count without obvious cause, was observed in 23% of sampled dolphins. Elevated eosinophil counts were associated with decreased T-lymphocyte proliferation and increased neutrophil phagocytosis. In addition, indication of chronic low-level exposure to another algal toxin, domoic acid produced by the diatom Pseudo-nitzschia spp., was determined. Previous studies of other marine mammal populations exposed recurrently to Pseudo-nitzschia blooms have suggested a possible link between the eosinophilia and domoic acid exposure. While the chronic eosinophilia syndrome could over the long-term produce organ damage and alter immunological status and thereby increase vulnerability to other challenges, the significance of the high prevalence of the syndrome to the observed mortality events in the St. Joseph Bay area is unclear. Nonetheless, the unusual immunological findings and concurrent evidence of domoic acid exposure in this sentinel marine species suggest a need for further investigation to elucidate potential links between chronic, low-level exposure to algal toxins and immune health.

Common polymorphisms in the NOD2 gene region are associated with leprosy and its reactive states

BACKGROUND

Because of its wide spectrum of clinical manifestations and its well-defined immunological complications, leprosy is a useful disease for studying genetic regulation of the host response to infection. We hypothesized that polymorphisms in the nucleotide-binding oligomerization domain containing 2 (NOD2) gene, for a cytosolic receptor known to detect mycobacteria, are associated with susceptibility to leprosy and its clinical outcomes.

METHODS

We used a case-control study design with 933 patients in Nepal. Our study included 240 patients with type 1 (reversal) reactions and 124 patients with type 2 (erythema nodosum leprosum) reactions. We compared the frequencies of 32 common polymorphisms in the NOD2 gene region between patients with the different clinical types of leprosy as well as between the patients and 101 control participants without leprosy.

RESULTS

Four polymorphisms were associated with susceptibility to leprosy when comparing allele frequencies, and 8 were associated when comparing genotype frequencies with a dominant model. Five polymorphisms were associated with protection from reversal reaction in an allelic analysis, and 7 were associated with reversal reaction with a dominant model. Four polymorphisms were associated with increased susceptibility to erythema nodosum leprosum in an allelic analysis, whereas 7 of 32 polymorphisms were associated with a dominant model.

CONCLUSION

These data suggest that NOD2 genetic variants are associated with susceptibility to leprosy and the development of leprosy reactive states.

IgA antibody response of swine to foot-and-mouth disease virus infection and vaccination

Foot-and-mouth disease virus (FMDV) continues to be a significant economic problem worldwide. Control of the disease involves the use of killed-virus vaccines, a control measure developed decades ago. After natural infection, the primary site of replication of FMDV is the pharyngeal area, suggesting that a mucosal immune response is the most effective. Humoral immunity to killed-virus vaccination induces antibodies that can prevent the clinical disease but not local infection. Determining whether infection or vaccination stimulates IgA-mediated local immunity depends on the method of analysis. Different assays have been described to analyze the quality of antibody responses of cattle and swine to FMDV, including indirect double-antibody sandwich enzyme-linked immunosorbent assay (IDAS-ELISA) and antibody capture assay-ELISA (ACA-ELISA). We tested these assays on swine and show that vaccinated animals had FMDV-specific IgM and IgG but no IgA in either serum or saliva. After the infection, both assays detected FMDV-specific IgM, IgG, and IgA in serum. Notably, serum IgA was more readily detected using the ACA-ELISA, whereas IgA was not detected in saliva with this assay. FMDV-specific IgA antibodies were detected in saliva samples using the IDAS-ELISA. These data show that parenterally administered, killed-virus vaccine does not induce a mucosal antibody response to FMDV and illuminates limitations and appropriate applications of the two ELISAs used to measure FMDV-specific responses. Further, the presence of the IgA antivirus in serum correlates with the presence of such antibodies in saliva.

Macrophage polarization in bacterial infections

Converging studies have shown that M1 and M2 macrophages are functionally polarized in response to microorganisms and host mediators. Gene expression profiling of macrophages reveals that various Gram-negative and Gram-positive bacteria induce the transcriptional activity of a "common host response," which includes genes belonging to the M1 program. However, excessive or prolonged M1 polarization can lead to tissue injury and contribute to pathogenesis. The so-called M2 macrophages play a critical role in the resolution of inflammation by producing anti-inflammatory mediators. These M2 cells cover a continuum of cells with different phenotypic and functional properties. In addition, some bacterial pathogens induce specific M2 programs in macrophages. In this review, we discuss the relevance of macrophage polarization in three domains of infectious diseases: resistance to infection, infectious pathogenesis, and chronic evolution of infectious diseases.

Dynamics of the cytokine response to Mycobacterium ulcerans during antibiotic treatment for M. ulcerans disease (Buruli ulcer) in humans

We have studied the evolution of the gamma interferon (IFN-gamma) and interleukin 10 (IL-10) responses after Mycobacterium ulcerans sonicate stimulation of whole blood from patients with early M. ulcerans lesions during treatment with rifampin and streptomycin for 8 weeks. Among the 26 patients, secretion of IFN-gamma increased during treatment, with a significant increase at 4 weeks and a further increase after 8 weeks overall. The increase was more rapid in patients with large or ulcerative lesions, becoming significant by 4 weeks. For small lesions, there was only a minor increase, which did not reach significance. There was no significant change in the median IL-10 response during antibiotic therapy, and there was no inverse correlation between IFN-gamma and IL-10 responses. These results demonstrate that an IFN-gamma secretory response to M. ulcerans developed, independently of IL-10 secretion, in patients whose M. ulcerans disease healed during antibiotic therapy.

Recovery of IFN-gamma levels in PBMCs from lepromatous leprosy patients through the synergistic actions of the cytokines IL-12 and IL-18

The shift to the production of a Th1 cytokine profile during an intracellular infection has been shown to depend on antigen presenting cells-derived IL-12 and T-cell-derived IFN-gamma production. IL-18 facilitates Th1 priming in synergy with IL-12 through the stimulation of IFN-gamma production by T cells, B cells, NK cells, macrophages and DCs. A low level of IFN-gamma production in PBMC cultures from lepromatous leprosy patients (LL) has been previously reported by several groups. We evaluated the synthesis of this cytokine after exogenous addition of recombinant IL-12 and IL-18 (IL12/IL18) in order to induce recovery of the IFN-gamma levels with Mycobacterium leprae antigenic stimulation. The aim of this study was to investigate if exogenous addition of IL12/IL18 to PBMC cell cultures in the presence of M. leprae antigens could induce recovery of IFN-gamma levels. We found that IFN-gamma levels in PBMCs cultured from LL patients were reestablished after exogenous addition of exogenous IL12/IL18 and we also observed a diminished IL-18R expression. Although the molecular mechanisms of IL12/IL18 synergy have not been clearly elucidated, we assume that recombinant cytokines can activate several transcription factors that induce IFN-gamma synthesis.

Interleukin-17 in pulmonary host defense

Interleukin (IL)-17A and IL-17F are produced by a novel class of effector alphabeta T cells called Th17 cells as well as gammadelta T cells. alphabeta IL-17-producing T cells are controlled by the transcription factor RORgammat and develop independent of GATA-3, T-bet, Stat 4, and Stat 6. Effector molecules produced by these cells include IL-17A, IL-17F, and IL-22. IL-17A and IL-17F bind to IL-17 receptor (IL-17R) and receptor signaling is critical for host defense against extracellular bacteria by regulating chemokine gradients for neutrophil emigration into infected tissue sites as well as via regulation of host granulopoiesis. Furthermore, it has recently been shown that IL-17 and IL-22 regulate the production of antimicrobial proteins in epithelium. Although Th17 cells are important in mucosal host defense, in the setting of retained antigenic stimulation, such as in the setting of asthma or chronic infection, such as in cystic fibrosis, or in the setting of autoimmunity, these cells can mediate immunopathology.

Th17 cells and mucosal host defense

Th17 cells are a new lineage of T-cells that are controlled by the transcription factor RORgammat and develop independent of GATA-3, T-bet, Stat 4 and Stat 6. Novel effector molecules produced by these cells include IL-17A, IL-17F, IL-22, and IL-26. IL-17RA binds IL-17A and IL-17F and is critical for host defense against extracellular planktonic bacteria by regulating chemokine gradients for neutrophil emigration into infected tissue sites as well as host granulopoiesis. Moreover, IL-17 and IL-22 regulate the production of antimicrobial proteins in mucosal epithelium. Although TGF-beta1 and IL-6 have been shown to be critical for development of Th17 cells from naive precursors, IL-23 is also important in regulating IL-17 release in mucosal tissues in response to infectious stimuli. Compared to Th1 cells, IL-23 and IL-17 show limited roles in controlling host defense against primary infections with intracellular bacteria such as Mycobacterium tuberculosis suggesting a predominate role of the Th17 lineage in host defense against extracellular pathogens. However, in the setting of chronic biofilm infections, as that occurs with cystic fibrosis or bronchiectasis, Th17 cells may be key contributors of tissue injury.

DC-SIGN association with the Th2 environment of lepromatous lesions: cause or effect?

The clinical spectrum of leprosy is related to patients' immune responses. Non-responsiveness towards Mycobacterium leprae (ML) seems to correlate with a Th2 cytokine profile. The reason for such a polarized immune response remains unclear. The C-type lectin, DC-SIGN, expressed by subsets of dendritic cells (DCs) and macrophages, has previously been associated with Th2 responses. Here we show abundant DC-SIGN expression in lepromatous but not borderline tuberculoid leprosy, in both HIV-positive and HIV-negative patients. Moreover, we demonstrate that DC-SIGN can act as an entry receptor for ML, as it does for M. tuberculosis, through the cell wall component lipoarabinomannan. DC-SIGN is expressed on virtually all ML-containing cells, providing further evidence for its role as a receptor. DC-SIGN may therefore be induced on macrophages in lepromatous leprosy and may then contribute to mycobacterial entry into these cells.

The continuing challenges of leprosy

Leprosy is best understood as two conjoined diseases. The first is a chronic mycobacterial infection that elicits an extraordinary range of cellular immune responses in humans. The second is a peripheral neuropathy that is initiated by the infection and the accompanying immunological events. The infection is curable but not preventable, and leprosy remains a major global health problem, especially in the developing world, publicity to the contrary notwithstanding. Mycobacterium leprae remains noncultivable, and for over a century leprosy has presented major challenges in the fields of microbiology, pathology, immunology, and genetics; it continues to do so today. This review focuses on recent advances in our understanding of M. leprae and the host response to it, especially concerning molecular identification of M. leprae, knowledge of its genome, transcriptome, and proteome, its mechanisms of microbial resistance, and recognition of strains by variable-number tandem repeat analysis. Advances in experimental models include studies in gene knockout mice and the development of molecular techniques to explore the armadillo model. In clinical studies, notable progress has been made concerning the immunology and immunopathology of leprosy, the genetics of human resistance, mechanisms of nerve injury, and chemotherapy. In nearly all of these areas, however, leprosy remains poorly understood compared to other major bacterial diseases.

Polarized helper T cells in tubercular pleural effusion: phenotypic identity and selective recruitment

Containment of Mycobacterium tuberculosis critically depends on orchestrated generation of Th1 cells and their selective recruitment at the pathologic sites. Understanding the mechanism involved in this process is important for defining better intervention strategies. We investigated the surface phenotype of Th1 cells and the role of chemotactic factors in their selective recruitment in tuberculosis pleural effusion and tuberculin site. Memory T cells obtained from the pleural fluid expressed a battery of homing receptors such as CD11a, CCR5 and CXCR3. Similar expression profile was noted on T cells infiltrating the tuberculin site. Expression of their respective ligands such as ICAM-1, RANTES, MIP1-alpha, Mig and IP-10 were detected at pathologic sites. In vitro assay of T cell adherence to activated human umbilical vein endothelial cells (HUVEC) expressing chemotactic ligands suggests an important role of these homing molecules in their selective trafficking. Here, we demonstrate a hierarchy of CXCR3 in effector cell adhesion to HUVEC in vitro, although CD11a and CCR5 were also observed to mediate cell adhesion in an additive fashion. Findings of the present study provide mechanistic insights into the critical events of T cell trafficking in tuberculosis and may help designing better therapeutic modalities.

Polymorphism of the 5' flanking region of the IL-12 receptor beta2 gene partially determines the clinical types of leprosy through impaired transcriptional activity

BACKGROUND

Individual differences in T cell responsiveness to interleukin 12 (IL-12), resulting from inherited factors, may be responsible for differences in the intensity of cell mediated immune (CMI) responses in patients with leprosy, a disease with a wide clinical spectrum.

AIM

Polymorphisms in the 5' flanking region of the IL12RB2 gene were analysed to determine potential immunogenetic factors affecting CMI responses, using leprosy as a model.

METHODS

Polymorphisms in the 5' flanking region of IL12RB2 were examined using direct sequencing techniques, and allele frequencies between patients with lepromatous leprosy and patients with tuberculoid leprosy were compared. The effect of these single nucleotide polymorphisms (SNPs) on IL12RB2 expression was estimated using the dual luciferase reporter gene assay in Jurkat T cells.

RESULTS

Several SNPs, including -1035A>G, -1023A>G, -650delG, and -465A>G, were detected within the 5' flanking region of IL12RB2. The frequency of haplotype 1 (-1035A, -1023A, -650G, -464A) was high in the general Japanese population, but was significantly lower in lepromatous patients compared with tuberculoid patients and healthy controls. Reporter gene assays using Jurkat T cells revealed that all haplotypes carrying one or more SNP exhibited a lower transcriptional activity compared with haplotype 1.

CONCLUSION

SNPs within the 5' flanking region of IL12RB2 affect the degree of expression of this gene and may be implicated in individual differences in CMI responsiveness to mycobacterial antigens, leading to lepromatous or tuberculoid leprosy.

Patterns of intracellular cytokines in CD4 and CD8 T cells from patients with mycobacterial infections

Using a short-term bulk culture protocol designed for an intracellular-staining method based on a flow cytometry approach to the frequencies of cytokine-producing cells from tuberculosis and leprosy patients, we found distinct patterns of T cell subset expression. The method also reveals the profile of peak cytokine production and can provide simultaneous information about the phenotype of cytokine-producing cells, providing a reliable assay for monitoring the immunity of these patients. The immune response of Mycobacterium leprae and purified protein derivative (PPD) in vitro to a panel of mycobacteria-infected patients from an endemic area was assessed in primary mononuclear cell cultures. The kinetics and source of the cytokine pattern were measured at the single-cell level. IFN-gamma-, TNF-alpha-, IL-4- and IL-10-secreting T cells were intracytoplasmic evaluated in an attempt to identify M. leprae- and PPD-specific cells directly from the peripheral blood. The analysis by this approach indicated that TNF-alpha was the first (8 h) to be produced, followed by IFN-gamma (16 h), IL-10 (20 h) and IL-4 (24 h), and double-staining experiments confirmed that CD4+ were a greater source of TNF-alpha than of CD8+ T cells (P < 0.05). Both T cell subsets secreted similar amounts of IFN-gamma. We conclude that the protocol permits rapid evaluation of cytokine production by different T cell populations. The method can also be used to define immune status in non-infected and contact individuals.

Leprosy

Leprosy remains an important health problem worldwide. The disease is caused by a chronic granulomatous infection of the skin and peripheral nerves with Mycobacterium leprae. The clinical range from tuberculoid to lepromatous leprosy is a result of variation in the cellular immune response to the mycobacterium. The resulting impairment of nerve function causes the disabilities associated with leprosy. This review summarises recent advances in understanding of the biology of leprosy, clinical features of the disease, the current diagnostic criteria, and the new approaches to treatment of the infection and the immune-mediated complications. Supervised multi-drug therapy (MDT) for fixed durations is highly effective for all forms of the disease. The widespread implementation of MDT has been associated with a fall in the prevalence of the leprosy but as yet no reduction in the case-detection rate globally. Thus, leprosy control activities must be maintained for decades to interrupt transmission of infection.

Monocytes of distinct clinical types of leprosy are differentially activated by cross-linking class II HLA molecules to secrete IL-12

Leprosy is characterized by a wide spectrum of clinical features depending on the individual differences in Th1-type immunity. The objective of this study was to evaluate whether monocyte activation by stimulus via class II HLA molecules would be correlated with the differences in cellular immune responses among diverse clinical forms of leprosy. IL-1beta and IL-12 productivity in monocyte preparations obtained from PBMCs was estimated in patients with lepromatous- and tuberculoid-type leprosy. We found that monocytes from lepromatous patients produced significantly higher (about 4-fold higher) amounts of IL-12 as compared to in patients with tuberculoid type of leprosy when class II HLA molecules were cross-linked with anti-HLA class II antibodies, whereas almost equal amounts of IL-1beta were produced from each monocyte preparation by stimulus via class II HLA molecules regardless of the clinical form of leprosy. These results suggest that monocyte activation differs between lepromatous and tuberculoid patients in terms of IL-12 secretion, which might be related to individual differences in the cellular immune responses according to the clinical type of leprosy.

Cytokine polarization in miliary and pleural tuberculosis

Cytokines were measured in patients with pleural effusion and miliary tuberculosis (TB). Patients with pleural effusion had significantly higher interferon-gamma (IFN-gamma) levels (P < 0.001) in their pleural fluid as compared to that of peripheral blood of the same patients, thus exhibiting localization of predominantly Th1-type immunity in the pleural fluid. On the contrary, patients with miliary TB had higher IFN-gamma levels in the peripheral blood as compared to their bronchoalveolar lavage fluid. Moreover, the median IFN-gamma: IL-4 ratio in the peripheral blood of miliary TB patients was two-fold higher as compared to bronchoalveolar lavage fluid, suggesting that the cytokine profile at the disease site is skewed toward a Th2-like bias. Further, flow cytometry data revealed a significantly higher (P < 0.001) percentage of CD4+ pleural fluid lymphocytes expressing IFN-gamma, whereas in the miliary TB, a nine-fold higher percentage of lymphocytes in bronchoalveolar lavage fluid expressed IL-4 in comparison with their peripheral CD4 T cells. Our data indicate, respectively, a Th1-like and Th2-like response in tuberculous pleural effusion and miliary TB, suggesting that these clinical forms of extrapulmonary tuberculosis probably reflect the extreme ends of a Th1-Th2 spectrum of the disease.

Molecular analysis of sarcoidosis tissues for mycobacterium species DNA

We performed polymerase chain reaction analysis, for Mycobacterium species 16S rRNA, rpoB, and IS6110 sequences, on 25 tissue specimens from patients with sarcoidosis and on 25 control tissue specimens consisting of mediastinal or cervical lymph nodes and lung biopsies. Mycobacterium species 16S rRNA sequences were amplified from 12 (48%) rpoB sequences and from 6 (24%) of the sarcoidosis specimens. In total, 16S rRNA or rpoB sequences were amplified from 15 sarcoidosis specimens (60%) but were not detected in any of the control tissues (p=0.00002, chi square). In three specimens, the sequences resembled Mycobacterium species other than M. tuberculosis. All specimens with sequences consistent with M. tuberculosis were negative for IS6110. We provide evidence that one of a variety of Mycobacterium species, especially organisms resembling M. tuberculosis, is found in most patients with sarcoidosis.

[Immunopathology of leprosy: the complexity of the mechanisms of host immune response to Mycobacterium leprae]

Leprosy, whose etiologic agent Mycobacterium leprae, is an illness of ample clinical and immunopathological spectrum. Its clinical manifestations are correlated with distinct immunologic forms, varying from a vigorous immune response mediated by cells to M. leprae, with Th1 standard in the tuberculoid polar region, to an absence of specific cellular response to antigens of M. leprae in the lepromatous polar region, with predominance of Th2 response and exacerbation of humoral response. It is probable that different polymorphic genes determine susceptibility to M. leprae. Additional studies are necessary to clarify the complex interactions between cytokines and the role of the phenotypic diversity of cells network that contribute to the host defense. The comprehension of such mechanisms will provide new insights for the identification of agonists and/or antagonists for pro- or anti-inflammatory effects, and also will indicate possible situations for its appropriate use in immunologic and/or immunotherapeutic interventions.

Inflammation and lymphocyte activation during mycobacterial infection in the interferon-gamma-deficient mouse

Interferon-gamma is a pivotal cytokine in the protective response to tuberculosis. In its absence rampant bacterial growth results in tissue destruction and death. While macrophage activation is key, this pleiotropic cytokine has other secondary but significant roles. To investigate these roles, both intravenous and aerosol infection of the IFN-gamma gene disrupted (GKO) mouse was performed. For the first time we describe the very similar growth of bacteria, during the initial phase of infection, between control and GKO mice. During this initial phase, however, very different histopathologic consequences between control and GKO mice were observed. Key observations included an early increased accumulation of granulocytes and a much more rapid and pronounced interstitial pneumonia in the GKO mice. As infection developed, GKO mice mounted an antigen-specific response; however, lymphocyte activation was much more rapid in these mice. Of interest is the fact that this increased rapidity occurred prior to significant differences in bacterial number. Taken together these data support a role for IFN-gamma in limiting both initial cellular recruitment and acquired lymphocytic responses to mycobacterial infection. This role may be key in surviving the kind of chronic stimulatory disease caused by Mycobacterium tuberculosis.

Association and linkage of leprosy phenotypes with HLA class II and tumour necrosis factor genes

Previous analyses indicate major gene control of susceptibility to leprosy per se and the HLA class II region has been implicated in determining susceptibility and control of clinical phenotype. Segregation analysis using data from 76 Brazilian leprosy multi-case pedigrees (1166 individuals) supported a two locus model as the best fit: a recessive major gene and a recessive modifier gene(s) (single locus vs two locus model, P = 0.0007). Combined segregation and linkage analysis to the major locus, showed strong linkage to HLA class II (HLA-DQB1 P = 0.000002, HLA-DQA1 P = 0.000002, HLA-DRB1 P = 0.0000003) and tumour necrosis factor genes (TNF P = 0.00002, LTA P = 0.003). Extended transmission disequilibrium testing, using multiple affected family members, demonstrated that the common allele TNF*1 of the -308 promoter region polymorphism showed linkage and/or association with disease per se, at a high level of significance (P < 0.0001). Two locus transmission disequilibrium testing suggested susceptibility (TNF*1/LTA*2) and protective (TNF*2/LTA*2) haplotypes in the class iii region. Taken together the segregation and HLA analyses suggest the possibility of more than one susceptibility locus in the MHC.

Characterization of an activation protein-1-binding site in the murine interleukin-12 p40 promoter. Demonstration of novel functional elements by a reductionist approach

Interleukin (IL)-12 is a heterodimeric cytokine produced by macrophages in response to intracellular pathogens and provides an obligatory signal for the differentiation of T-helper-1 cells. We previously reported an analysis of the IL-12 p40 promoter in RAW264.7 macrophages. Multiple control elements were involved in activation of transcription by bacterial products. A critical control element, located between -96 and -88, interacts with C/EBP family members. In this study, using a strategy to demonstrate functional activity in a minimal promoter context, three novel cis-acting elements are found to have an important role in IL-12 p40 promoter activation by lipopolysaccharide. One of these elements is characterized in detail. Mutations from -79 to -74 in the murine IL-12 p40 promoter significantly reduce lipopolysaccharide-induced promoter activity. Electrophoretic mobility shift assays demonstrate binding of AP-1 family members to this region. Spacing between the C/EBP and AP-1 site is important for promoter activation, suggesting cooperativity between these elements. c-Jun and a mutant c-Jun molecule activate the IL-12 p40 promoter and synergistically activate the promoter when co-expressed with C/EBPbeta. Finally, this region of the promoter is demonstrated to be a target for mitogen-activated protein kinase and toll-like receptor signaling pathways.

Differences in lymphocyte subpopulations from peripheral blood and lymphoid organs in natural caprine tuberculosis infection

Although the cell-mediated immune response is known to be a critical factor in host defence against intracellular mycobacterial infection, the different components of the T-cell response are unclear, particularly in caprine infection. In this study we examine the differences in the lymphocyte population of peripheral blood, spleen and mediastinal and superficial lymph nodes in 11 naturally infected goats showing positive reactions in the comparative tuberculine intradermal test. According to the different types of lesion showing, the goats were classified into proliferative or exudative tuberculosis. The results obtained by fflow cytometry analysis indicated that the main differences in peripheral blood were in the CD4 T-cell population, which decreased markedly in goats with exudative tuberculosis, while the CD8 and B cells increased in number. The gamma/delta T cells did not show significant differences in either type of tuberculosis, while interleukin-2 receptor cells decreased slightly in the exudative tuberculosis. The CD4:CD8 ratio was higher than 1 in goats with proliferative tuberculosis and lower than 1 in goats with exudative tuberculosis. In general, the lymphoid organs of the goats with exudative tuberculosis showed a significant increase in the number of CD8 T cells (CD4:CD8 ratio of less than 1) whereas no significant differences were observed in the CD4 T population between either type of tuberculosis.

The relative proportions of secreted interleukin-2 and interleukin-10 determine the magnitude of rheumatoid arthritis T-cell proliferation to the recall antigen tuberculin purified protein derivative

OBJECTIVE

To investigate the mechanisms of the deficient proliferative responses by rheumatoid arthritis (RA) peripheral blood T cells to the recall antigen tuberculin purified protein derivative (PPD).

METHODS

The concomitant production of interleukin (IL)-2, IL-10 and lymphocyte proliferation were studied by enzyme-linked immunosorbent assay and [(3)H]thymidine uptake, respectively, in 12 normal controls and eight RA patients.

RESULTS

An inverse correlation was found between IL-10 production and proliferation to PPD. The proliferative response was shown to be critically affected by the IL-2:IL-10 ratio so that absolute levels of secreted IL-2 or IL-10 correlated non-significantly with lymphocyte proliferation.

CONCLUSION

The deficient T-cell proliferation in RA peripheral blood mononuclear cells is related to the relative proportions of IL-2:IL-10 rather than the absolute amounts secreted.

Differential representations of memory T cell subsets are characteristic of polarized immunity in leprosy and atopic diseases

We identified functionally polarized subsets of CD4 memory T cells on the basis of the expression of CD11a, CD45RA and CD62L. Within the several phenotypically distinct subsets of CD4 memory cells are two that, upon stimulation, produce primarily IL-4 (MT(2), CD45RA(-)CD62L(+)CD11a(dim)) or primarily IFN-gamma (MT(1), CD45RA(-)CD62L(-)CD11a(bright)). In addition, four other phenotypically distinct subsets of CD4 cells have unique cytokine profiles. To determine the clinical relevance of the representation of these cell types, we analyzed blood from patients with the chronic diseases leprosy and atopy. These diseases are characterized as immunologically polarized, since T cell responses in affected individuals are often strongly biased towards T(h)1 (dominated by IFN-gamma production) or T(h)2 (IL-4 production). We show here that this polarization reflects homeostatic or differentiation mechanisms affecting the representation of the functionally distinct subsets of memory CD4 T cells, MT(1) and MT(2). Significantly, the representation of the MT(1) and MT(2) subsets differs dramatically between subjects with tuberculoid leprosy (a T(h)1 disease), or lepromatous leprosy or atopic disease (T(h)2 diseases). However, there was no difference in the cytokine profiles of these or any of the other finely resolved CD4 subsets, when compared between individuals across all disease states. Thus, it is the representation of these subsets in peripheral blood that is diagnostic of the polarized state of the immune system.