Fonsecaea pedrosoi infection induces differential modulation of costimulatory molecules and cytokines in monocytes from patients with severe and mild forms of chromoblastomycosis

The host defense mechanism in chromoblastomycosis has not been thoroughly investigated. It has been suggested that cell- mediated immunity in patients with long- standing chromoblastomycosis is somehow impaired. As a result, these individuals became unable to develop an efficient immune reaction. Many studies have shown that monocyte- derived macrophages exhibit critical activities in immunity to microorganisms. Moreover, the ability of cells from the monocytic lineage to process and present antigens, to produce cytokines, and to provide costimulatory signals confirms their pivotal role in the initiation of specific immune responses. In the present study, it was observed that monocytes from patients with a severe form of disease had a higher production of IL- 10 and a lower expression of HLA- DR and costimulatory molecules when stimulated with specific antigen or LPS. Immune modulation with recombinant IL- 12 or anti- IL- 10 can restore the antigen- specific Th1- type immune response in chromoblastomycosis patients by up- regulating HLA- DR and costimulatory molecules in monocytes. Therefore, our data show that monocytes from patients with different clinical forms of chromoblastomycosis present distinct phenotypic and functional profiles. This observation suggests possible mechanisms that control the T cell response and influence their role in the development of pathology.

Nucleic acid vaccines: tasks and tactics

There are no adequate vaccines against some of the new or reemerged infectious scourges such as HIV and TB. They may require strong and enduring cell-mediated immunity to be elicited. This is quite a task, as the only known basis of protection by current commercial vaccines is antibody. As DNA or RNA vaccines may induce both cell-mediated and humoral immunity, great interest has been shown in them. However, doubt remains whether their efficacy will suffice for their clinical realization. We look at the various tactics to increase the potency of nucleic acid vaccines and divided them broadly under those affecting delivery and those affecting immune induction. For delivery, we have considered ways of improving uptake and the use of bacterial, replicon or viral vectors. For immune induction, we considered aspects of immunostimulatory CpG motifs, coinjection of cytokines or costimulators and alterations of the antigen, its cellular localization and its anatomical localization including the use of ligand-targeting to lymphoid tissue. We also thought that mucosal application of DNA deserved a separate section. In this review, we have taken the liberty to discuss these enhancement methods, whenever possible, in the context of the underlying mechanisms that might argue for or against these strategies.

Physiological, morphological and behavioural effects of selecting zebra finches for divergent levels of corticosterone

The effects of environmental stress on the physiology and behaviour of higher vertebrates has become an important avenue of research in recent years. Evidence from recent studies has suggested that the avian stress-related hormone corticosterone (CORT) may play a role in immunocompetence and sexual selection. We tested whether CORT is immunosuppressive by studying humoral and cell-mediated immune responses in populations of captive zebra finches selected for divergent peak levels of CORT. We also investigated whether selection for peak CORT has an effect on the quality of several sexually selected regions of the male zebra finch; in addition we compared morphometric parameters and the dominance ranking in males from the different selection lines. We also tested whether different components of the immune system compete for limited resources. We found that selection for divergent levels of peak CORT had little effect on humoral immunity, male sexual signal quality or dominance ranking. However, contrary to expectations, we did find a positive relationship between CORT titre and cell-mediated immunity, as well as a greater cell-mediated response in the birds selected for high CORT titre than those selected for low CORT titre. Consistent with predictions, significant negative relationships were found between both testosterone and CORT titre on humoral immunity. Birds from the low CORT lines were significantly larger in terms of skeletal size than those from the high CORT lines. Overall, our results suggest that the cell-mediated immune response is associated with a reduction in the humoral response, but only in males, and that there is no simple relationship between peak CORT levels and immune function.

Killer T cells in influenza

Antigen-specific CD8+ T cells play an important role in virus clearance. Here we review the current understanding of influenza virus-specific CD8+ T cell immunity in experimental mouse models and humans. The characteristics and nature of CD8+ T cell killing are discussed, as is the selection and maintenance of the influenza-specific effector and memory repertoires. Consideration is given to vaccine strategies and to the effects of ageing. Understanding the complexities of CD8+ T cell mediated immunity and memory has the potential for improving vaccine design, particularly to combat pandemics caused by newly emerging influenza viruses.

HIV-1 down-modulates γ signaling chain of FcγR in human macrophages : a possible mechanism for inhibition of phagocytosis

HIV-1 infection impairs a number of macrophage effector functions, thereby contributing to development of opportunistic infections and the pathogenesis of AIDS. FcγR-mediated phagocytosis by human monocyte-derived macrophages (MDM) is inhibited by HIV-1 infection in vitro, and the underlying mechanism was investigated in this study. Inhibition of phagocytosis directly correlated with the multiplicity of HIV-1 infection. Expression of surface FcγRs was unaffected by HIV-1 infection, suggesting that inhibition of phagocytosis occurred during or after receptor binding. HIV-1 infection of MDM markedly inhibited tyrosine phosphorylation of the cellular proteins, which occurs following engagement of FcγRs, suggesting a defect downstream of initial receptor activation. FcγR-mediated phagocytosis in HIV-infected MDM was associated with inhibition of phosphorylation of tyrosine kinases from two different families, Hck and Syk, defective formation of Syk complexes with other tyrosine-phosphorylated proteins, and inhibition of paxillin activation. Down-modulation of protein expression but not mRNA of the γ signaling subunit of FcγR (a docking site for Syk) was observed in HIV-infected MDM. Infection of MDM with a construct of HIV-1 in which nef was replaced with the gene for the γ signaling subunit augmented FcγR-mediated phagocytosis, suggesting that down-modulation of γ-chain protein expression in HIV-infected MDM caused the defective FcγR-mediated signaling and impairment of phagocytosis. This study is the first to demonstrate a specific alteration in phagocytosis signal transduction pathway, which provides a mechanism for the observed impaired FcγR-mediated phagocytosis in HIV-infected macrophages and contributes to the understanding of how HIV-1 impairs cell-mediated immunity leading to HIV-1 disease progression.

Inhibitory effect of antidepressant drugs on contact hypersensitivity reaction

Background: Contact hypersensitivity (CS) reaction in the skin is T-cell mediated immune reaction which plays a major role in the pathogenesis and chronicity of various inflammatory skin disorders and, like other delayed-type hypersensitivity (DTH) reactions, affords immunity against tumor cells and microbes. CS response is a self-limiting reaction, and interleukin (IL)-10 is considered to be a natural suppressant of cutaneous inflammatory response. Recently, it has been demonstrated that major depression is related to activation of the inflammatory response and elevation of some parameters of cell-mediated immunity. It has been suggested that such activation of the immune system may play a role in etiology of depression. If this immunoactivation is involved in etiology of depression, one would expect that antidepressant agents may have negative immunoregulatory effects. To the best of our knowledge, the effect of antidepressants on contact hypersensitivity has not been studied.

Methods: The aim of the present study was to establish the effect of prolonged desipramine or fluoxetine treatment on CS reaction to picryl chloride.

Results: Antidepressants significantly suppressed CS reaction, fluoxetine by 53% whereas desipramine by 47% compared to positive control. Moreover, desipramine and fluoxetine decreased relative weight of auxillary lymph nodes. Desipramine decreased also relative weight of inguinal lymph nodes and spleens whereas desipramine and fluoxetine increased production of IL-10 in comparison to positive control.

Conclusion: The observed effect of antidepressant drugs on CS reaction is consistent with the hypothesis that T-cell mediated immunity is targeted by antidepressants.

Fungal Mastoiditis in immunocompromised children

The immunocompromised host is subject to a variety of opportunistic infections. Mycotic infections, including invasive fungal sinusitis, are a dreaded complication in immune deficient children. Fungal mastoiditis has rarely been described in this population. Our experience with 2 cases of fungal mastoiditis in immunocompromised children is reviewed. Case histories describing aggressive medical management with and without surgical intervention and a review of the literature are presented.Fungal mastoiditis is a rare entity described in isolated case reports in the adult literature. It is seen almost entirely in immunocompromised patients, particularly those lacking cell-mediated immunity. The first case of Aspergillus mastoiditis was described in 1985.1 Reports of fungal mastoiditis have been primarily of patients with leukemia, and, more recently, of patients with acquired immunodeficiency syndrome.2,3 Using a computerized search of the MEDLINE database, we identified 1 report (in a non–English language journal) of fungal mastoiditis in a pediatric patient.4 We report 2 cases of fungal mastoiditis in immunosuppressed children.

Toward Omics-Based, Systems Biomedicine, and Path and Drug Discovery Methodologies for Depression-Inflammation Research.

Meta-analyses confirm that depression is accompanied by signs of inflammation including increased levels of acute phase proteins, e.g., C-reactive protein, and pro-inflammatory cytokines, e.g., interleukin-6. Supporting the translational significance of this, a meta-analysis showed that anti-inflammatory drugs may have antidepressant effects. Here, we argue that inflammation and depression research needs to get onto a new track. Firstly, the choice of inflammatory biomarkers in depression research was often too selective and did not consider the broader pathways. Secondly, although mild inflammatory responses are present in depression, other immune-related pathways cannot be disregarded as new drug targets, e.g., activation of cell-mediated immunity, oxidative and nitrosative stress (O&NS) pathways, autoimmune responses, bacterial translocation, and activation of the toll-like receptor and neuroprogressive pathways. Thirdly, anti-inflammatory treatments are sometimes used without full understanding of their effects on the broader pathways underpinning depression. Since many of the activated immune-inflammatory pathways in depression actually confer protection against an overzealous inflammatory response, targeting these pathways may result in unpredictable and unwanted results. Furthermore, this paper discusses the required improvements in research strategy, i.e., path and drug discovery processes, omics-based techniques, and systems biomedicine methodologies. Firstly, novel methods should be employed to examine the intracellular networks that control and modulate the immune, O&NS and neuroprogressive pathways using omics-based assays, including genomics, transcriptomics, proteomics, metabolomics, epigenomics, immunoproteomics and metagenomics. Secondly, systems biomedicine analyses are essential to unravel the complex interactions between these cellular networks, pathways, and the multifactorial trigger factors and to delineate new drug targets in the cellular networks or pathways. Drug discovery processes should delineate new drugs targeting the intracellular networks and immune-related pathways.

Influence of Th1/Th2 cytokines and nitric oxide in murine systemic infection induced by Sporothrix schenckii

In an attempt to elucidate the effects of Sporothrix schenckii infection on the immune response, our laboratory has developed a murine model of disseminated sporotrichosis. Helper T cells can be further subdivided into Th1 and Th2 phenotypes. The differentiation of two subsets of T lymphocytes is driven by IL-12 and IL-4 cytokines, respectively. Th1 cells produce IFN-gamma that activate macrophages and promote cell-mediated immunity. In addition, we found low levels of iNOS and NO production in the initial (1st and 2nd weeks) and final (9th and 10th weeks) periods of the infection, in contrast with the period of week 4 to 7 of elevated values. The determination of IFN-gamma and IL-12 are in agreement with NO/iNOS detection, showing the presence of cellular immune response throughout the infectious process. However, the production of IL-4 shows an increase in levels after the 5th and 6th weeks suggesting a participation of Th2 response in this period as well. Regarding these results, the study demonstrated that in experimental sporotrichosis infection the cellular immune response participated throughout the period analyzed as a nitric oxide dependent mechanism. In contrast, the presence of Th2 response began in the 5th week, suggesting the participation of humoral immune response in advanced stages of sporotrichosis.

Lymphocyte transformation assay for C neoformans antigen is not reliable for detecting cellular impairment in patients with Neurocryptococcosis

Background: Cryptococcus neoformans causes meningitis and disseminated infection in healthy individuals, but more commonly in hosts with defective immune responses. Cell-mediated immunity is an important component of the immune response to a great variety of infections, including yeast infections. We aimed to evaluate a specific lymphocyte transformation assay to Cryptococcus neoformans in order to identify immunodeficiency associated to neurocryptococcosis (NCC) as primary cause of the mycosis.Methods: Healthy volunteers, poultry growers, and HIV-seronegative patients with neurocryptococcosis were tested for cellular immune response. Cryptococcal meningitis was diagnosed by India ink staining of cerebrospinal fluid and cryptococcal antigen test (Immunomycol-Inc, SP, Brazil). Isolated peripheral blood mononuclear cells were stimulated with C. neoformans antigen, C. albicans antigen, and pokeweed mitogen. The amount of H-3-thymidine incorporated was assessed, and the results were expressed as stimulation index (SI) and log SI, sensitivity, specificity, and cut-off value (receiver operating characteristics curve). We applied unpaired Student t tests to compare data and considered significant differences for p<0.05.Results: The lymphotoxin alpha showed a low capacity with all the stimuli for classifying patients as responders and non-responders. Lymphotoxin alpha stimulated by heated-killed antigen from patients with neurocryptococcosis was not affected by TCD4+ cell count, and the intensity of response did not correlate with the clinical evolution of neurocryptococcosis.Conclusion: Response to lymphocyte transformation assay should be analyzed based on a normal range and using more than one stimulator. The use of a cut-off value to classify patients with neurocryptococcosis is inadequate. Statistical analysis should be based on the log transformation of SI. A more purified antigen for evaluating specific response to C. neoformans is needed.

Clinical presentation of tuberculoid leprosy in an epidermodysplasia verruciformis patient

Epidermodysplasia verruciformis (EV) is triggered by a variety of mechanisms that at least partly include genetic background. We present a Brazilian man with a 30-year history of flat, wart-like lesions with clinical, histopathological, and evolutive aspects consistent with papillomavirus (HPV)-associated EV. Histological analysis of the wart lesions showed epidermis with hyperkeratosis, regular acanthosis, hypergranulosis, and cells with abundant basophilic cytoplasm. Moreover, a perivascular lymphocytic infiltrate was found in the superficial dermis, consistent with a viral wart. Type-2-HPV DNA was detected in various fragments of skin-wart lesions using the polymerase chain reaction (PCR). Two years after the EV diagnosis, the patient presented with an anesthetic well-demarcated, erythematous and mildly scaly plaque on his right forearm. A histopathological analysis of this lesion demonstrated the presence of a compact tuberculoid granuloma. Ziehl-Neelsen staining demonstrated the presence of rare acid-fast bacilli and confirmed the tuberculoid leprosy diagnosis. The patient's Mitsuda Intradermal Reaction was positive. To elucidate the possible mechanism involved in this case of EV, we genotyped the HLA genes of this patient. DQB genotyping showed the polymorphic HLA alleles DQB1*0301 and 0501. The patient was treated with a paucibacillary multidrug therapy scheme, and the disease was cured in six months. This report describes an EV patient with an M. leprae infection, confirming that tuberculoid leprosy patients possess a relatively specific and efficient cell-mediated immunity against the bacillus and, therefore, localized forms of the disease. Moreover, we show the possible involvement of the polymorphic HLA alleles DQB1*0301 and 0501 in EV induction mechanisms.

Effects of propolis from Brazil and Bulgaria on fungicidal activity of macrophages against Paracoccidioides brasiliensis

Paracoccidioidomycosis is the most important systemic mycosis in Latin America. Its etiological agent, Paracoccidoides brasiliensis, affects individuals living in endemic areas through inhalation of airborne conidia or mycelial fragments. The disease may affect different organs and systems, with multiple clinical features, with cell-mediated immunity playing a significant role in host defence. Peritoneal macrophages from BALB/c mice were stimulated with Brazilian or Bulgarian propolis and subsequently challenged with P, brasiliensis. Data suggest an increase in the fungicidal activity of macrophages by propolis stimulation, independently from its geographic origin, (C) 2002 Elsevier B.V. Ireland Ltd. All rights reserved.

The Effect of Propolis on Th1/Th2 Cytokine Expression and Production by Melanoma-bearing Mice Submitted to Stress

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Paracoccidioidomycosis associated with acquired immunodificiency syndrome: report of seven cases

São apresentadas as características clínicas e evolutivas de sete pacientes (cinco masculinos e dois do sexo feminino), a maioria dos quais usuários de drogas ilícitas endovenosa, com paracoccidioidomicose associada à Síndrome da Imunodeficiência Adquirida (SIDA/AIDS). em quatro pacientes a paracoccidioidomicose comprometia os pulmões isoladamente, nos demais a doença era generalizada com envolvimento cutâneo. Apenas dois pacientes eram procedentes recentes da zona rural. O que nos faz presumir que nos demais a paracoccidioidomicose doença resultou da reativação de focos latentes da infecção. Dado o papel da imunidade medida por células na defesa do hospedeiro contra o Paracoccidioides brasiliensis, é de se prever crescente ocorrência da associação paracoccidioidomicose -SIDA/AIDS nas áreas endêmicas para ambas as enfermidades.

EXPERIMENTAL PARACOCCIDIOIDOMYCOSIS OF HAMSTER INOCULATED IN THE CHEEK POUCH

We compared the granuloma morphology and immune response of hamsters inoculated with Paracoccidioides brasiliensis (Pb) into the cheek pouch, which lacks lymphatic drainage, and into the footpad, which is rich in lymphatics. Our objective was to better understand the modulation of Pb granuloma in an immunocompetent animal inoculated in an immunologically privileged site. The humoral immune response (ELISA) and cell mediated immunity (footpad test) became positive on days 7 and 14, respectively in animals inoculated into footpad and on days 35 and 60 in animals inoculated into the pouch. Typical epithelioid granulomas were observed at both sites on day 14. The number of fungi gradually decreased from the beginning of the experiment in footpad lesions, but only after day 35 in pouch granulomas, when cell mediated immunity was detectable. The results indicate that typical epithelioid paracoccidioidomycotic granulomas may develop in the absence of a detectable immune response; however, they are incapable of controlling fungal reproduction. Lack of lymphatic drainage delays the appearance of a detectable immune response, but with time fungi escape from the pouch, elicit an immune response and reach other organs. Our results further indicate the importance of the lymphatics in the pathogenesis of paracoccidioidomycosis.