Pioneer factors: roles and their regulation in development

Pioneer factors are a subclass of transcription factors that can bind and initiate opening of silent chromatin regions. Pioneer factors subsequently regulate lineage-specific genes and enhancers and, thus, activate the zygotic genome after fertilization, guide cell fate transitions during development, and promote various forms of human cancers. As such, pioneer factors are useful in directed cell reprogramming. In this review, we define the structural and functional characteristics of pioneer factors, how they bind and initiate opening of closed chromatin regions, and the consequences for chromatin dynamics and gene expression during cell differentiation. We also discuss emerging mechanisms that modulate pioneer factors during development.

The chromatin signatures of enhancers and their dynamic regulation

Enhancers are cis-regulatory elements that can stimulate gene expression from distance, and drive precise spatiotemporal gene expression profiles during development. Functional enhancers display specific features including an open chromatin conformation, Histone H3 lysine 27 acetylation, Histone H3 lysine 4 mono-methylation enrichment, and enhancer RNAs production. These features are modified upon developmental cues which impacts their activity. In this review, we describe the current state of knowledge about enhancer functions and the diverse chromatin signatures found on enhancers. We also discuss the dynamic changes of enhancer chromatin signatures, and their impact on lineage specific gene expression profiles, during development or cellular differentiation.

SETDB1/NSD-dependent H3K9me3/H3K36me3 dual heterochromatin maintains gene expression profiles by bookmarking poised enhancers

Gene silencing by heterochromatin plays a crucial role in cell identity. Here, we characterize the localization, the biogenesis, and the function of an atypical heterochromatin, which is simultaneously enriched in the typical H3K9me3 mark and in H3K36me3, a histone mark usually associated with gene expression. We identified thousands of dual regions in mouse embryonic stem (ES) cells that rely on the histone methyltransferases SET domain bifurcated 1 (SETDB1) and nuclear set domain (NSD)-containing proteins to generate H3K9me3 and H3K36me3, respectively. Upon SETDB1 removal, dual domains lose both marks, gain signatures of active enhancers, and come into contact with upregulated genes, suggesting that it might be an important pathway by which genes are controlled by heterochromatin. In differentiated tissues, a subset of these dual domains is destabilized and becomes enriched in active enhancer marks, providing a mechanistic insight into the involvement of heterochromatin in the maintenance of cell identity.

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H3K9me3 and H3K36me3 dual domains form on thousands of regions in ES cells

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Dual domains depend on SETDB1 and NSD enzymes

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Most upregulated genes in Setdb1 KO cells are not normally heterochromatinized

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Dual domains become enhancers for these genes upon Setdb1 loss

SETDB1-dependent heterochromatin stimulates alternative lengthening of telomeres

Alternative lengthening of telomeres, or ALT, is a recombination-based process that maintains telomeres to render some cancer cells immortal. The prevailing view is that ALT is inhibited by heterochromatin because heterochromatin prevents recombination. To test this model, we used telomere-specific quantitative proteomics on cells with heterochromatin deficiencies. In contrast to expectations, we found that ALT does not result from a lack of heterochromatin; rather, ALT is a consequence of heterochromatin formation at telomeres, which is seeded by the histone methyltransferase SETDB1. Heterochromatin stimulates transcriptional elongation at telomeres together with the recruitment of recombination factors, while disrupting heterochromatin had the opposite effect. Consistently, loss of SETDB1, disrupts telomeric heterochromatin and abrogates ALT. Thus, inhibiting telomeric heterochromatin formation in ALT cells might offer a new therapeutic approach to cancer treatment.

Determination of avidity of IgG against protein antigens from Streptococcus pneumoniae: assay development and preliminary application in clinical settings

The measurement of antibody levels is a common test for the diagnosis of Streptococcus pneumoniae infection in research. However, the quality of antibody response, reflected by avidity, has not been adequately evaluated. We aimed to evaluate the role of avidity of IgG against eight pneumococcal proteins in etiologic diagnosis. Eight pneumococcal proteins (Ply, CbpA, PspA1 and 2, PcpA, PhtD, StkP-C, and PcsB-N) were used to develop a multiplex bead-based avidity immunoassay. The assay was tested for effects of the chaotropic agent, multiplexing, and repeatability. The developed assay was applied to paired samples from children with or without pneumococcal disease (n = 38 for each group), determined by either serology, polymerase chain reaction (PCR), or blood culture. We found a good correlation between singleplex and multiplex assays, with r ≥ 0.94.The assay was reproducible, with mean inter-assay variation ≤ 9% and intra-assay variation < 6%. Children with pneumococcal disease had lower median avidity indexes in the acute phase of disease for PspA1 and 2 (p = 0.042), PcpA (p = 0.002), PhtD (p = 0.014), and StkP-C (p < 0.001). When the use of IgG avidity as a diagnostic tool for pneumococcal infection was evaluated, the highest discriminative power was found for StkP-C, followed by PcpA (area under the curve [95% confidence interval, CI]: 0.868 [0.759-0.977] and 0.743 [0.607-879], respectively). The developed assay was robust and had no deleterious influence from multiplexing. Children with pneumococcal disease had lower median avidity against five pneumococcal proteins in the acute phase of disease compared to children without disease.

Prevalence and risk factors for wheezing in Salvador, Brazil: a population-based study

BACKGROUND

Wheezing is one of the most frequent causes of visit to emergency rooms among children. However, data on wheezing burden are mostly provided at healthcare setting, and particularly only for infants.

AIMS

We sought to estimate the prevalence of wheezing in children under 4 years and to assess potential risk factors in the community.

DESIGN

This was a cross-sectional analysis of a population-based cohort study.

METHODS

The sample comprised children aged <4 years living in Salvador, Brazil. Data were collected via home visits when the parents/guardians were interviewed. Data were recorded on standardized forms.

RESULTS

Of 1534 children, mean age was 21 ± 14 months (minimum 3 days; maximum 47 months; 6% <2 months); 780 (51%) were males and 501 [33%; 95% confidence interval (95% CI): 30-35%] reported wheezing in the last 12 months. Among wheezers, 321 (64%) had occasional wheezing. Overall, 180 (12%; 95% CI: 10-14%) had recurrent wheezing and 157 (10%; 95% CI: 9-12%) had asthma. For children in the first, second, third and fourth year of life wheezing was reported in 23, 41, 34 and 37%, respectively. Mother atopic-related disease was independently associated with recurrent wheezing (AdjPR[95% CI]: 1.54 [1.12-2.11]) and asthma (AdjPR[95% CI]: 1.54 [1.10-2.16]). Smoker at home (AdjPR[95% CI]: 1.34 [1.07-1.67]) and low birth weight (AdjPR[95%CI]: 1.38 [1.05-1.81]) were independently associated with occasional wheezing.

CONCLUSIONS

One-third of under 4 years reported wheezing; history of mother's atopic-related disease was an independent risk factor for recurrent wheezing and asthma; smoker at home and low birth weight were independent risk factors for occasional wheezing.

Changes in amounts of total salivary gland proteins of Lutzomyia longipallpis (Diptera: Psychodidae) according to age and diet

Saliva plays important roles in facilitation of a bloodmeal, lubrication of mouthparts, and parasite transmission for some vector insects. Salivary composition changes during the lifetime of an insect, and differences in the salivary profile may influence its functions. In this report, the amount and profile of salivary gland protein of the American visceral leishmaniasis vector Lutzomyia longipalpis (Lutz & Neiva, 1912) were analyzed at different times of insect development and diet. Protein content from unfed female sand flies increased significantly with age, and a significant difference was observed in sugar-fed females during the first 10 d of adult life. Salivary protein content sharply decreased 1 d after blood feeding, with gradual increase in concentration the following days. SDS-polyacrylamide gel electrophoresis analysis revealed that most polypeptides present in the saliva of sugar-fed also were present in the saliva of blood-fed females. Understanding changes in sand fly's saliva contents at distinct days after emergence and the influence of a bloodmeal in this aspect may reveal the role played by saliva during leishmaniasis transmission.

Role of Sand Fly Saliva in Human and Experimental Leishmaniasis: Current Insights

Leishmaniases are wide spread diseases transmitted to their vertebrate host by infected sand fly. The saliva from these arthropods contains a vast repertoire of pharmacologically active molecules that hampers the host's haemostatic, inflammatory and immune responses. The early interactions between Leishmania and the host's immune response are closely linked to disease evolution or protection against the protozoan, and the ectoparasite saliva contributes directly to these interactions. Current studies have depicted these features, and these relations are being widely explored. There are concrete indications that the host response against sand fly saliva influences disease outcome in leishmaniasis. Additionally, there are demonstrations that immunization with whole sand fly saliva, or its components, leads to protection against leishmaniasis in different host species. The combination of these evidences opens up optimistic perspectives for improving vaccine development against Leishmania infection.

Experimental model of chronic osteomyelitis caused by Leishmania (L) amazonensis

Experimental animal models have been used for the study of the physiopathogenesis of leishmaniasis, on some occasions with success, while in other situations such as bone alterations that accompany tegumentary leishmaniasis, especially in diffuse cutaneous form (DCL), the mechanisms are still unknown. In the present study, we determined these alterations in an animal model susceptible to Leishmania (L) amazonensis. Amastigotes of L. (L) amazonensis isolated from patients with diffuse cutaneous leishmaniasis (DCL) were inoculated into the hind paws of eight BALB/c mice, macroscopic and histopathological aspects were analyzed. After 90 and 120 days of evolution, histopathological analysis demonstrated a mononuclear cell infiltrate rich in plasma cells and intense parasitism of intra- and extra-medullary macrophages, with areas of bone necrosis and discrete involvement of cartilaginous tissue. The results show that the inflammatory process developed during L. (L) amazonensis infection might cause bone tissue destruction and secondarily affect the joints.

Imaging exams of bone lesions in patients with diffuse cutaneous leishmaniasis (DCL)

We studied bone lesion alterations in three patients with diffuse cutaneous leishmaniasis (DCL) by imaging exams (radiography and scintigraphy) and histopathology. Two patients had bone lesions of distal extremities of hands and feet, and one infiltrating plaques in the skin. The study was conducted at three specialized centers (Presidente Dutra Hospital/Nucleus of Tropical Pathology, UFMA-MA; Gonçalo Moniz Research Center-FIOCRUZ-BA; Laboratory of Pathology of Infectious Diseases (LIM-50), University of São Paulo, SP). Three-phase bone scintigraphy demonstrated high sensitivity and specificity for bone lesions, showing increased uptake of the radiopharmaceutical at sites of active lesions. In contrast, radiography demonstrated lytic lesions, cortical destruction and local osteopenia of the bone extremeties in two patients. Histopathological analysis showed sequestration with presence of amastigote forms of Leishmania (osteomyelitis), mononuclear cells and macrophages containing amastigote forms of Leishmania in one patient. These preliminary data indicate that imaging exams (radiography and scintigraphy) are important in the evaluation of bone lesions in diffuse cutaneous leishmaniasis and should be included in the routine histopathological diagnosis of the disease and follow-up of bone lesions.

The susceptibility of domestic cats (Felis catus) to experimental infection with Leishmania braziliensis

Over the last few years, several cases of feline leishmaniasis (FL) with cutaneous and visceral forms have been reported around the world. Nonetheless, the real susceptibility of cats to infection with Leishmania spp. and the outcome of leishmaniasis in these animals are poorly understood. Experimental studies on feline models will contribute to the knowledge of natural FL. Thus, in order to determine the susceptibility of domestic cats (Felis catus) to experimental infection with Leishmania braziliensis, 13 stray cats were infected with 10(7) promastigotes by the intradermal route in the ear and nose simultaneously and followed up for 72 weeks. Soon after infection, the earliest indication of a lesion was a papule on the ear at 2 weeks post-infection (w.p.i.). The emergence of satellite papules around the primary lesion was observed about 4 w.p.i. Two weeks later these papules coalesced and formed a huge and irregular nodule. Thereafter, there was lesion dissemination to the external and marginal surface of the ipsilateral ear, and later to the contralateral ear. At 10 w.p.i., some nodules became ulcerated. Nose lesions presented a similar evolution. At both sites, the largest lesion sizes occurred at 10 w.p.i. and started to decrease 15 days later. Ear and nose nodules healed at 32 and 40 w.p.i., respectively. Specific L. braziliensis IgG antibody titers (optical density> or = 0.01 as positive result) were detected as early as 2 w.p.i. (0.09 +/- 0.02) in only three animals (23%), and all cats had positive titers at 20 w.p.i. (0.34 +/- 0.06). Only three animals (38%) continued to show positive serology at 72 w.p.i. (0.08 +/- 0.02). Up to that time, none of the cats had lesion recurrence. In a feline model of cutaneous leishmaniasis, it seems that there is no correlation between active lesions and positive serology. The implications of these data are discussed.

Leishmanial infection: analysis of its first steps. A review

The first steps in leishmaniasis are critical in determining the evolution of the disease. Major advances have recently been done in understanding this crucial moment. Fundamental research in parasite-vector interaction, parasite biology, insect saliva, and vertebrate host response have shed new light and uncovered a most fascinating and complex moment in leishmaniasis. We review here some of these aspects and we try to connect them in a logical framework.

B-cell infiltration and frequency of cytokine producing cells differ between localized and disseminated human cutaneous leishmaniases

Biopsies from human localized cutaneous lesions (LCL n = 7) or disseminated lesions (DL n = 8) cases were characterized according to cellular infiltration,frequency of cytokine (IFN-gamma, TNF-alpha) or iNOS enzyme producing cells. LCL, the most usual form of the disease with usually one or two lesions, exhibits extensive tissue damage. DL is a rare form with widespread lesions throughout the body; exhibiting poor parasite containment but less tissue damage. We demonstrated that LCL lesions exhibit higher frequency of B lymphocytes and a higher intensity of IFN-gamma expression. In both forms of the disease CD8+ were found in higher frequency than CD4+ T cells. Frequency of TNF-alpha and iNOS producing cells, as well as the frequency of CD68+ macrophages, did not differ between LCL and DL. Our findings reinforce the link between an efficient control of parasite and tissue damage, implicating higher frequency of IFN-gamma producing cells, as well as its possible counteraction by infiltrated B cells and hence possible humoral immune response in situ.

Risk factors associated with asymptomatic infection by Leishmania chagasi in north-east Brazil

Various factors have been associated with a predisposition to the development of clinical American visceral leishmaniasis (AVL). However, little information is available about the factors that predispose to asymptomatic infection. To identify the risk factors associated with asymptomatic infection, a study was carried out between July 1997 and June 1998 on children aged 0-5 years in the districts of Vila Nova and Bom Viver in the municipality of Raposa in the island of São Luís, State of Maranhão, Brazil. A questionnaire containing socioeconomic, demographic and epidemiological data was used. The delayed-type hypersensitivity (DTH) test was carried out on 639 children in the first phase, and on 572 in the second, 7 months after the first survey, using Leishmania amazonensis antigen. Infection was determined by enzyme-linked immunosorbent assay (ELISA) in 638 children during the first phase, and in 572 during the second. Six outcome measures were used: initial prevalence, final prevalence and incidence, each determined by DTH and ELISA. The incidence of infection was 10.8% when determined by DTH and 28.5% when determined by ELISA. After adjustment for confounding variables using Cox regression, infection by L. chagasi was associated with child's age (> or = 2 years), location of the dwellings (Vila Nova) and reporting of relatives with AVL. Bathing outside the house and playing outdoors between 18:00 and 20:00 were identified as risk factors in some analyses but not in others. Presence of intra- and peridomestic Lutzomyia sandflies and animals such as dogs or chickens in the house or in the neighbourhood appeared as risk factors in some analyses but in others they unexpectedly seemed to protect from infection. Malnutrition was not found to be associated with infection.

Differences in gamma interferon production in vitro predict the pace of the in vivo response to Leishmania amazonensis in healthy volunteers

The initial encounter of Leishmania cells and cells from the immune system is fundamentally important in the outcome of infection and determines disease development or resistance. We evaluated the anti-Leishmania amazonensis response of naive volunteers by using an in vitro priming (IVP) system and comparing the responses following in vivo vaccination against the same parasite. In vitro stimulation allowed us to distinguish two groups of individuals, those who produced small amounts of gamma interferon (IFN-gamma) (n = 16) (low producers) and those who produced large amounts of this cytokine (n = 16) (high producers). IFN-gamma production was proportional to tumor necrosis factor alpha and interleukin 10 (IL-10) levels but did not correlate with IL-5 production. Volunteers who produced small amounts of IFN-gamma in vitro remained low producers 40 days after vaccination, whereas high producers exhibited increased IFN-gamma production. However, 6 months after vaccination, all individuals tested produced similarly high levels of IFN-gamma upon stimulation of their peripheral blood mononuclear cells with Leishmania promastigotes, indicating that low in vitro producers respond slowly in vivo to vaccination. In high IFN-gamma producers there was an increased frequency of activated CD8(+) T cells both in vitro and in vivo compared to the frequency in low producers, and such cells were positive for IFN-gamma as determined by intracellular staining. Such findings suggest that IVP responses can be used to predict the pace of postvaccination responses of test volunteers. Although all vaccinated individuals eventually have a potent anti-Leishmania cell-mediated immunity (CMI) response, a delay in mounting the CMI response may influence resistance against leishmaniasis.

Interleukin 8 as a vaso-occlusive marker in Brazilian patients with sickle cell disease

Sickle cell disease has a worldwide distribution and is a public health problem in Brazil. Although vaso-occlusive crisis (VOC) is one of the most important clinical features of the disease, there are still several steps of its pathogenesis which are unknown. The increase of the chemotactic factor interleukin 8 (IL-8) has been reported to be involved in sickle cell disease crisis, but this has not been demonstrated conclusively. In the present study we analyzed serum IL-8 levels by ELISA and hematological parameters and hemoglobin patterns by standard techniques in 23 (21 SS and 2 SC) Brazilian patients with sickle cell syndromes during VOC caused by different inducing factors, 22 (21 SS and 1 SC) sickle cell patients out of crisis, and 11 healthy controls. Increased IL-8 levels were observed in 19 of 23 VOC patients (79.2%), 3 of them with more than 1,000 pg/ml. Seventeen of 22 (77.3%) non-crisis patients showed low IL-8 levels (less than 15 pg/ml). Healthy controls had low IL-8 levels. A significant difference in serum IL-8 levels was observed between crisis and non-crisis sickle cell patients (P<0.0001). There was no correlation between IL-8 levels and hematological data or hemoglobin patterns. High serum IL-8 levels were observed in VOC patients independently of the crisis-inducing factor. We conclude that in the studied population, IL-8 concentration may be a useful VOC marker, although the mechanism of the pathogenic process of sickle cell VOC syndromes remains unclear.

[Leishmania (Leishmania) chagasi infection in children from an endemic area of visceral leishmaniasis in the São Luís Island-MA, Brazil]

A prospective study was undertaken in 648 children with less than 6 years of age in the municipality of Raposa, Maranhão, Brazil, from June 1997 to June 1998, to evaluate the characteristics of the infection by L.(L.)chagasi and verify if there is an association between malnutrition and asymptomatic infection. A standardized questionnaire was used containing socioeconomic, environmental and behavioral data. Montenegro skin reaction (IDRM) with L. amazonensis and Enzyme Linked Immunosorbent Assay (ELISA) test to detect infection, and anthropometric examination were performed. Initial and final prevalence and incidence of infection were 18.6%, 20.6% and 10.8% as measured by IDRM and 13.5%, 34.4% and 28% according to ELISA. The prevalence of chronic malnutrition was 26%. No association was detected between malnutrition and asymptomatic infection by L. (L.) chagasi. More effective control measures are needed in these areas since asymptomatic infection seems to be on the increase.

Flow cytometric determination of cellular sources and frequencies of key cytokine-producing lymphocytes directed against recombinant LACK and soluble Leishmania antigen in human cutaneous leishmaniasis

Leishmaniasis, caused by infection with the protozoan parasite Leishmania, affects millions of individuals worldwide, causing serious morbidity and mortality. This study directly determined the frequency of cells producing key immunoregulatory cytokines in response to the recombinant antigen Leishmania homolog of receptors for activated kinase C (LACK) and soluble leishmania antigen (SLA), and it determined relative contributions of these antigens to the overall cytokine profile in individuals infected for the first time with Leishmania braziliensis. All individuals presented with the cutaneous clinical form of leishmaniasis and were analyzed for proliferative responses to LACK antigen and SLA, frequency of lymphocyte subpopulations (analyzed ex vivo), and antigen-induced (LACK and SLA) cytokine production at the single-cell level (determined by flow cytometry). The following were determined. (i) The Th1-type response previously seen in patients with cutaneous leishmaniasis is due to gamma interferon (IFN-gamma) production by several different sources, listed in order of contribution: CD4(+) T lymphocytes, CD4(-), CD8(-) lymphocytes, and CD8(+) T lymphocytes. (ii) SLA induced a higher frequency of lymphocytes producing IFN-gamma and tumor necrosis factor alpha (TNF-alpha) than did LACK. (iii) LACK induced an activation of monocyte populations as reflected by an increased percentage of CD14-positive cells. (iv) Neither SLA nor LACK induced detectable frequencies of cells producing interleukin-4 (IL-4) or IL-5. These data demonstrated a multifaceted immune response to SLA in human leishmaniasis involving Th1 CD4(+) T lymphocytes (IFN-gamma(+) and IL-10(-)/IL-4(-)), Tc1 CD8(+) T cells (IFN-gamma(+), and IL-10(-)/IL-4(-)), and a high frequency of TNF-alpha-producing lymphocytes. Moreover, it was determined that the recombinant antigen LACK acts as a weak inducer of Th1-type lymphocyte responses compared to SLA.

Human immune response to sand fly salivary gland antigens: a useful epidemiological marker?

Antibody (IgG) responses to salivary gland homogenate and to a recombinant salivary protein from the sand fly Lutzomyia longipalpis were investigated using sera from children living in an endemic area of visceral leishmaniasis in Brazil. We classified children into four groups according to their responses to Leishmania antigen: (Group I) positive serology and positive delayed type hypersensitivity (DTH), (Group II) positive serology and negative DTH, (Group III) negative serology and positive DTH, and (Group IV) negative serology and negative DTH. A highly significant correlation was found between anti-salivary gland IgG levels and DTH responses. An L. longipalpis salivary recombinant protein used as an antigen in an enzyme-linked immuno sorbent assay (ELISA) gave a significant but different result. A positive correlation was found between anti-Leishmania IgG and anti-recombinant protein IgG titers. The results indicate that sand fly salivary proteins may be of relevance to the study the epidemiology of leishmaniasis.

A simple method for human peripheral blood monocyte isolation

We describe a simple method using percoll gradient for isolation of highly enriched human monocytes. High numbers of fully functional cells are obtained from whole blood or buffy coat cells. The use of simple laboratory equipment and a relatively cheap reagent makes the described method a convenient approach to obtaining human monocytes.

Mucosal leishmaniasis: quantitative nasal cytology as a marker of disease activity and indicator of healing

Mucosal leishmaniasis (ML) follow-up is based on subjective parameters. Using simplified quantitative cytology of nasal lavages (QNCs), we studied 20 ML patients, 10 patients with cutaneous leishmaniasis (CL), and 10 healthy subjects. Patients with ML were treated with antimony and followed up with otolaryngological examination plus QNCs for 6 months. At the first evaluation, the median total number of cells in ML patients (1,540,000) was greater than that in CL patients (215,000) or that in healthy subjects (250,000). Neutrophils were predominant in ML patients, in contrast to both sets of controls, in whom epithelial cells were more frequent. During treatment, we found a significant reduction in total nasal cell counts in ML patients who were cured, and encountered a switch in predominant cell type. The cytology of 2 patients who did not respond to antimony remained the same. It is therefore possible to detect nasal inflammation in ML patients through QNCs, which may indicate extension of mucosal involvement, providing an objective parameter to monitor therapy.

Down-regulation of Th1 type of response in early human American cutaneous leishmaniasis

This study examined the T cell responses in the early phase of Leishmania braziliensis infection. Cytokine profiles, lymphoproliferative responses, and skin test results in 25 patients with early cutaneous leishmaniasis (ECL; illness duration <60 days) were compared with those in persons with late cutaneous leishmaniasis (LCL; illness duration >2 months). Absent or low lymphoproliferative responses were observed in 8 (32%) of 25 patients and an absence of interferon (IFN)-gamma production in 9 (41%) of 22 patients prior to therapy. IFN-gamma production in ECL (mean +/- SD) was lower than in LCL (293+/-346 vs. 747+/-377 pg/mL, respectively; P<.01). In contrast, interleukin (IL)-10 production in ECL (mean +/- SD) was higher than in LCL (246+/-56 vs. 50+/-41 pg/mL, respectively; P<.01). Restoration of lymphoproliferative responses and IFN-gamma production was achieved when monoclonal antibody to IL-10 or IL-12 was added to the cultures. These results show that T cell responses during early-phase infection are down-regulated by IL-10 and may facilitate parasite multiplication.

[Outbreak of American cutaneous leishmaniasis in Canoa, Santo Amaro, Bahia, Brazil]

An outbreak of American cutaneous leishmaniasis (ACL) was detected in the village of Canoa in 1993. A prospective observational study was outlined to determine the frequency rates and to clinically characterize the disease. A total of 555 people were followed up. There were 29 cases of ACL, 11 cases of probably previous ACL (scars) and 529 healthy individuals. Of these 529 individuals, 65 had a positive Montenegro reaction without any present or past evidence of leishmaniasis. The prevalence of ACL during the two years was 5.2% (29/555). The leishmania involved was Leishmania braziliensis and the vector, Lutzomyia intermedia. Evidence of infection was detected in dogs and horses. The high frequency of the disease among children under ten years, the similar sex distribution of cases and a component of familial aggregation suggest a peri- or intra-domiciliary transmission.

A dhfr-ts- Leishmania major knockout mutant cross-protects against Leishmania amazonensis

E10-5A3 is a dhfr-ts- Leishmania major double knockout auxotrophic shown previously to induce substantial protection against virulent L. major infection in both genetically susceptible and resistant mice. We investigated the capacity of dhfr-ts- to protect against heterologous infection by L. amazonensis. The degree of protection was evaluated by immunization of BALB/c or C57BL/6 mice with E10-5A3, followed by L. amazonensis challenge. Whether immunized by subcutaneous (SC) or intravenous (IV) inoculation, susceptible and resistant mice displayed a partial degree of protection against challenge with virulent L. amazonensis. SC-immunized BALB/c mice developed lesions 40 to 65% smaller than non immunized mice, while IV immunization led to protection ranging from 40 to 75% in four out of six experiments compared to non immunized animals. The resistant C57BL/6 mice displayed comparable degrees of protection, 57% by SC and 49% by IV immunization. Results are encouraging as it has been previously difficult to obtain protection by SC vaccination against Leishmania, the preferred route for human immunization.

Immunochemotherapy with interferon-gamma and multidrug therapy for multibacillary leprosy

Treatment for multibacillary leprosy is presently performed with a multidrug therapy (MDT) scheme maintained for 2 years. Leprosy treatment however can benefit from the reduction of length. The lack of interferon-gamma (IFN-gamma) production by lepromatous leprosy (LL) patients' lymphocytes lead us to use this cytokine in the treatment of multibacillary leprosy associated with MDT in the treatment of multibacillary leprosy, and monitor several clinical and immunological parameters during the course of treatment. A total of 20 multibacillary leprosy patients were evaluated, 10 treated with MDT alone, and 10 treated with MDT + 10 daily doses of 2 x 10(6) international units (IU) of recombinant human IFN-gamma/m2 followed by 10 daily doses of 10(7) IU IFN-gamma/m2, intramuscularly, during the first 20 days of MDT. IFN-gamma was well tolerated and did not cause any increase in the rate of leprosy reactions development during treatment. Decrease of bacillary load, fall of anti-Mycobacterium leprae IgG serum antibodies, changes of histological pattern, as well as changes in lymphocyte proliferation assay in response to mitogens (PHA or PWM), M. leprae antigen or PPD was similar in both groups of patients. Among several soluble immunological markers measured before and 30 days after beginning of treatment, levels of soluble IL-2R receptor increased in patients treated with MDT plus IFN-gamma whereas decreased in patients treated with MDT alone. Soluble ICAM-1 levels decreased in the MDT group but did not change in the MDT + IFN-gamma treated patients. Soluble CD4 and soluble CD8 markers did not change significantly in either group of patients. Neopterin, a marker of macrophage activation, increased in all but one patient treated with MDT + IFN-gamma but in none treated with MDT alone, indicating that IFN-gamma was active in vivo. Our findings indicate that despite being able to promote macrophage activation in multibacillary leprosy patients a short course of systemically administered IFN-gamma is not able to change the clinical course of a long standing disease such as leprosy.

Clinical observations of unresponsive mucosal leishmaniasis

We report the long-term clinical follow-up of two patients with unresponsive mucosal leishmaniasis due to Leishmania (Viannia) braziliensis from the Três Braços area in Bahia State, Brazil. Both were agricultural male workers with extensive upper respiratory mucosal involvement that was not cured with conventional and experimental therapy.

Production of host-protective (IFN-gamma), host-impairing (IL-10, IL-13) and inflammatory (TNF-alpha) cytokines by PBMC from leprosy patients stimulated with mycobacterial antigens

The production of IFNgamma, IL-10, IL-13 and TNFalpha was determined using PBMC from 7 tuberculoid (TT) and 7 lepromatous leprosy (LL) patients, after stimulation with several mycobacterial antigens, in an attempt to characterize the cytokine responses to these antigens. The results showed that TT patients displayed higher IFNgamma levels than LL patients with the mycobacterial antigens tested, but no differences in IL-10 production were observed between the two groups. MLSC antigen was associated with the lowest IFNgamma production in TT and LL groups. Only BCG could be identified with stimulation of IFNgamma production in some LL patients. The mycobacterial antigens SP+, SP- and BCG were associated with higher TNFalpha production in patients and controls, suggesting that these antigens could be involved in immunopathological effects. Our findings showed that the antigens tested were associated with a heterogeneous cytokine production in leprosy patients. Further studies are required to establish if an individual antigen can be identified as inducing a protective immune response in leprosy.

Human_leishmaniasis/cytokines.bahia.br

The cell-mediated immune response is critical in the resistance to and recovery from leishmaniasis. Cytokines are central elements in mounting an immune response and have received a great deal of attention in both human and experimental leishmaniasis. IFN-gamma is responsible for macrophage activation leading to leishmanicidal mechanisms. Understanding the balance of cytokines that lead to enhanced production of or synergize with IFN-gamma, and those cytokines that counterbalance its effects is fundamental for developing rational immunotherapeutic or immunoprophylactic approaches to leishmaniasis. Here we focus on the cytokine balance in human leishmaniasis, particularly IL-10 as an IFN-gamma opposing cytokine, and IL-12 as an IFN-gamma inducer. The effects of these cytokines were evaluated in terms of several parameters of the human immune response. IL-10 reduced lymphocyte proliferation, IFN-gamma production and cytotoxic activity of responsive human peripheral blood mononuclear cells. Neutralization of IL-10 led to partial restoration of lymphoproliferation, IFN-gamma production and cytotoxic activity in unresponsive visceral leishmaniasis patients. IL-12 also restored the responses of peripheral blood mononuclear cells from visceral leishmaniasis patients. The responses obtained with IL-12 are higher than those obtained with anti-IL-10, even when anti-IL-10 is combined with anti-IL-4.

Parasite-driven in vitro human lymphocyte cytotoxicity against autologous infected macrophages from mucosal leishmaniasis

Parasite-specific cytotoxicity in human leishmaniasis was evaluated in an autologous system. PBL from cutaneous leishmaniasis (CL) or mucosal leishmaniasis (ML) patients were exposed to Leishmania amazonensis-infected autologous macrophages for 7 days and then used as effector cells in a cytotoxic assay using 51Cr-labeled autologous infected macrophages as targets. Results are reported as LU per 10(7) PBMC. Cytotoxic activity is present in ML (9.7 +/- 2.1 LU/10(7) PBMC) but not in CL (1.5 +/- 2.4 LU/10(7) PBMC) patients' lymphocytes, and the differences were highly significant (p &lt; 0.0001). Both CD8+ T cells and NK cells exhibited cytotoxic activity. Addition of rIL-12, but not of IFN-gamma, during the generation of effector cells increased cytotoxic responses against infected macrophages. On the other hand, addition of mAb against human IL-12 or IFN-gamma during the stimulation of PBL significantly decreased the cytotoxic responses. Addition of IL-10 led to diminished cytotoxic responses, whereas the addition of anti-IL-10 did not significantly increase the cytotoxic responses. The observation of parasite-driven autologous cytotoxic responses in patients with ML, the destructive form of leishmaniasis, but not in CL, suggests that this phenomenon is involved in tissue pathology rather than in protection. Understanding the regulation of cytotoxic responses in leishmaniasis may be relevant to strategies aimed at limiting pathologic tissue destruction.

Parasite-driven in vitro human lymphocyte cytotoxicity against autologous infected macrophages from mucosal leishmaniasis

Parasite-specific cytotoxicity in human leishmaniasis was evaluated in an autologous system. PBL from cutaneous leishmaniasis (CL) or mucosal leishmaniasis (ML) patients were exposed to Leishmania amazonensis-infected autologous macrophages for 7 days and then used as effector cells in a cytotoxic assay using 51Cr-labeled autologous infected macrophages as targets. Results are reported as LU per 10(7) PBMC. Cytotoxic activity is present in ML (9.7 +/- 2.1 LU/10(7) PBMC) but not in CL (1.5 +/- 2.4 LU/10(7) PBMC) patients' lymphocytes, and the differences were highly significant (p < 0.0001). Both CD8+ T cells and NK cells exhibited cytotoxic activity. Addition of rIL-12, but not of IFN-gamma, during the generation of effector cells increased cytotoxic responses against infected macrophages. On the other hand, addition of mAb against human IL-12 or IFN-gamma during the stimulation of PBL significantly decreased the cytotoxic responses. Addition of IL-10 led to diminished cytotoxic responses, whereas the addition of anti-IL-10 did not significantly increase the cytotoxic responses. The observation of parasite-driven autologous cytotoxic responses in patients with ML, the destructive form of leishmaniasis, but not in CL, suggests that this phenomenon is involved in tissue pathology rather than in protection. Understanding the regulation of cytotoxic responses in leishmaniasis may be relevant to strategies aimed at limiting pathologic tissue destruction.

Variation of cytokine patterns related to therapeutic response in diffuse cutaneous leishmaniasis

Diffuse cutaneous leishmaniasis is a rare entity characterized by disseminated cutaneous nodules associated with specific anergy to leishmanial antigens. A low but not absent IFN-gamma expression by cells present in cutaneous lesions has been documented during the active phase of diffuse cutaneous leishmaniasis. In this study we confirm this observation, and extend it by showing a similar pattern in peripheral blood mononuclear cells and the variation of mRNA cytokine expression pattern during different stages of the disease. During active disease, patients did not express mRNA for IFN-gamma, while expressing mRNA for IL-2, IL-4, and IL-10. In contrast, an expression of IFN-gamma and low IL-10 was observed after treatment-induced transient healing of cutaneous lesions. In three patients we have been able to analyze a third PBMC sample obtained after clinical relapse, documenting in all of them decreased IFN-gamma expression with no expression of IL-10. Although there was an association between the appearance of IFN-gamma expression and clinical improvement, with marked expression of IFN-gamma mRNA and decreased expression of mRNA for IL-10 after treatment, this was not sufficient to prevent relapse in these patients. Therefore, it is possible that factors other than the cytokines characteristic of the Th1 and Th2 balance are implicated in the inability of diffuse cutaneous leishmaniasis patients to mount an anti-Leishmania immune response causing clinical improvement.

[Open therapeutic study with aminosidine sulfate in mucosal leishmaniasis caused by Leishmania (Viannia) braziliensis]

From September to November 1994. 21 patients with active mucosal leishmaniasis were treated with aminosidine sulphate 16 mg/kg/day by intramuscular injection for 20 days. They were principally adult male agricultural workers. Thirteen patients had not received specific treatment and eight had failed to respond to Glucantime therapy. Diagnosis was based on clinical and epidemiological observations, a search for the parasite, leishmanin skin sensitivity and indirect fluorescent antibody serological tests. Sixty seven percent of patients had leishmania parasites isolated from inoculated hamsters or visualized in imprints or histopathological sections. The mean follow-up period was 12.6 months. All patients completed treatment. Side effects were pain at the injection site (86%); mild proteinuria (24%), elevated serum creatinine (.5%) and subclinical bearing loss in one of two patients who did audiometric tests. Clinical cure was achieved in 48% and the accumulated relapse rate was 29% (4/14).

Tegumentary leishmaniasis in childhood

Very little has been published about tegumentary leishmaniasis in children and there are many controversies about this disorder in the literature. Therefore, we discuss the pathogenesis, clinical aspects, means to diagnosis, and treatment of this endemic disease.

Cytotoxicity in patients with different clinical forms of Chagas' disease

There are few studies on cell-mediated cytotoxicity in human Chagas' disease. In the present study, we evaluated peripheral blood mononuclear cell (PBMC) cytotoxicity activity from chagasic patients with different clinical forms of disease. To verify the cytotoxic response, we performed cell lysis assays using 51Cr-labelled K562 cells as targets. Results are reported as lytic units (LU = number of cells required for 30% lysis) per million PBMC. Exposure of patients' PBMC to Trypanosoma cruzi antigen led to an increase in cytotoxic activity compared with unstimulated patient cells against K562. Asymptomatic cardiomyopathy patients had higher responses (37.8 +/- 5.0 LU/10(6) PBMC; mean +/- s.d.) than indeterminate (11.5 +/- 3.6 LU/10(6) and symptomatic cardiomyopathy (7.8 +/- 2.5 LU/10(6)). Normal control PBMC stimulated with T. cruzi antigen had 4.36 +/- 1.31 LU/10(6)) PBMC against K562. Addition of recombinant interferon-gamma (IFN-gamma) did not lead to significant increase in cytotoxicity in any group of patients. On the other hand, recombinant human IL-12 significantly increased cytotoxic responses from symptomatic cardiomyopathy patients and normal controls who presented low levels of cytotoxicity induced by T. cruzi antigen. The combined use of IL-12 and a neutralizing anti-IFN-gamma antibody did not change IL-12-induced cytotoxic responses, showing the direct role of this cytokine on natural killer (NK) cells. NK cells were the main cells responsible for the lysis of K562 target cells as evidenced by testing cell subsets following magnetic cell sorting. These data demonstrate that chagasic patients with different clinical forms of disease have PBMC which respond to T. cruzi antigen with a cytotoxic response, and this response is up-regulated by IL-12.

[Comparative study of meglumine antimoniate, pentamidine isethionate and aminosidine sulfate in the treatment of primary skin lesions caused by Leishmania (Viannia) braziliensis]

With the aim of comparing the therapeutic efficacy, tolerability and toxicity of meglumine antimoniate, aminosidine sulphate and pentamidine isethionate, a field study was conducted on randomized treatment of patients with primary cutaneous leishmaniasis due to Leishmania (Viannia) braziliensis (L(V)b), in Corte de Pedra, BA, from October 1992 up to January 1993. Forty six patients were treated and distributed into three groups, two with 15 and one with 16 subjects. All patients were submitted to clinical examination, histopathological and immunological investigations, as diagnostic criterium. All patients were treated by intramuscular route. Group 1 received pentamidine 4 mg/kg/every 2 days, for 8 applications; Group 2 received aminosidine 20 mg/kg/day, for 20 days, and Group 3 received meglumine 10 mg Sbv/kg/day, for 20 days. Failure of therapy was defined as ulceration of the skin lesion four months after treatment. Such failure occurred in five cases as follows: two cases in patients of group 1 one case in patients of group 2, and two cases in group 3, after the first year of follow up. In the evaluation after three years we reviewed fifteen patients, five in each group; except for one in Group 3, all of them were cured. Statistical significance of the results between the three schedules used was not verified.

Biological behavior of Leishmania amazonensis isolated from humans with cutaneous, mucosal, or visceral leishmaniasis in BALB/C mice

Leishmania amazonensis causes a wide spectrum of disease in humans. In this study, we evaluated BALB/c mice infected with five strains of L. amazonensis isolated from patients with either cutaneous, mucosal, or visceral leishmaniasis. Mice infected with cutaneous and mucosal isolates developed ulcerating footpad lesions with parasite-loaded macrophages and extensive tissue destruction. Skin metastases, early dissemination of parasites to the spleen, and high anti-Leishmania antibody levels were also noted. Mice infected with L. amazonensis strains isolated from patients with visceral disease had a controlled infection, with small footpad lesions with mononuclear cell infiltration, few infected macrophages, and granuloma formation. They had no skin metastases, delayed dissemination of the parasite to the spleen, lower levels of IgG and higher levels of IgG2a against L. amazonensis. These findings demonstrate an unexpected resistance of BALB/c mice to the infection with L. amazonensis isolated from patients with visceral leishmaniasis. This resistance seems to be due to differences in these parasites that may be related to the altered course of the disease in humans and in isogenic BALB/c mice.

In vivo protective effect of the lectin from Canavalia brasiliensis on BALB/c mice infected by Leishmania amazonensis

In vivo administration of Canavalia brasiliensis lectin (at the time of infection, or maintained throughout the infection) reduced the lesions of highly susceptible BALB/c mice infected by Leishmania amazonensis. At the doses used C. brasiliensis lectin (ConBr) does not interfere with penetration or fate of Leishmania in the macrophages in vitro. Since Interferon-gamma (IFN-gamma) is the major macrophage activating factor, and considered a critical element in the successful immune response against leishmaniasis, we explored its participation in this phenomenon. ConBr either in vivo or in vitro induced IFN-gamma production in normal or in leishmania-infected BALB/c mice. However we were unable to change the course of disease by in vivo IFN-gamma administration (although IFN-gamma preparations were effective in inducing a leishmanicidal effect in vitro on L. amazonensis-infected peritoneal macrophages). Additionally, IFN-gamma neutralization with anti-IFN-gamma monoclonal antibody did not alter the protection conferred by ConBr administration. These data show that lectin administration in vivo is protective in the otherwise unchecked L. amazonensis infection of BALB/c mice, and suggest that such effect is not mediated by IFN-gamma.

Serum soluble markers in the evaluation of treatment in human visceral leishmaniasis

Visceral leishmaniasis (VL) has a fatal course if not properly treated. Recovery from VL is linked to cellular immune response. Unresponsiveness to antimonial therapy reinforces the importance of determining parameters for treatment assessment. We analysed the pre- and post-treatment serum levels of soluble CD4 (sCD4), sCD8, sIL-2R, soluble intercellular adhesion molecule-1 (sICAM-1) and neopterin in groups of VL patients either responsive or not to standard antimonial therapy. Pretreatment serum levels of all markers except for sICAM-1 were significantly higher in VL patients than in healthy subjects from the same area (P < 0.05). sICAM-1 levels were similar in healthy controls and in VL patients refractory to antimonial therapy (P = 0.25), but significantly higher in patients responsive to treatment (P = 0.02). The comparison of pre- and post-treatment concentrations showed that all markers, except sCD4 and sICAM-1, presented a significant fall (P < 0.05) in patients responsive to antimonial therapy. However, only neopterin presented with levels compatible with those of healthy subjects at the end of treatment (P = 0.30). In refractory patients sICAM-1 presented with post-treatment levels significantly higher than the pretreatment determinations (P = 0.03), while sCD4 experienced a significant drop (P = 0.01). All markers displayed clearly distinct behaviour according to the patient's response to therapy. This makes all soluble molecules studied suitable for use as indicators of antimonial therapy response. Additionally the comparison of pretreatment levels of the markers between responders and refractory patients to antimonial therapy showed that serum concentrations of sIL-2R and sICAM-1 significantly differed among these two groups (P = 0.02 in each case), suggesting that they may be used in future as predictors of antimonial therapy response.

[An evolutionary study of mucosal leishmaniasis (a 7- to 17-year follow-up) due to Leishmania (Viannia) braziliensis in Tres Braços, Bahia]

Seventy seven (68%) patients with mucosal leishmaniasis recorded during the period 1976-1986 in the region of Três Braços, Bahia were traced and re-evaluated clinically, diagnostically and therapeutically. Sixty-five patients were alive. The families of 12 dead patients were interviewed about probable cause of death. The 65 patients had a fresh clinical examination supplemented when necessary by a skilled ENT examination. All had a titre of circulating immunofluorescent antibodies estimated at the time. Eight patients with active mucosal lesions had triturated biopsies which were cultivated in NNN medium and inoculated in hamsters to attempt to recover Leishmania. The isolates were identified by monoclonal antibodies as Leishmania (Viannia) braziliensis. Fifty-six (86%) patients were judged clinically cured. Nine (13%) had active lesions. Of the 12 patients who died 5 (41%) had no signs of activity at death. Mucosal leishmaniasis was thought to be the direct cause of death in 3 patients. The field treatment programme at Três Braços has managed to clinically cure 61 patients (79%) during 17 years. Follow-up periods were a mean of 10 years (range 7-17).

Transforming growth factor-beta in human cutaneous leishmaniasis

Transforming growth factor (TGF)-beta has several downregulatory functions on the immune system: inhibition of interleukin-2 receptor induction, decrease of interferon-gamma-induced class II antigen expression, inhibition of macrophage activation, as well as cytotoxic and lymphokine-activated killer cell generation. TGF-beta has also been recognized as an important immunoregulator in murine leishmaniasis, for which it increases susceptibility to disease. In the present study we evaluate the involvement of TGF-beta in human leishmaniasis in vitro and in patients with cutaneous leishmaniasis. Human macrophages produce active TGF-beta after infection by Leishmania amazonensis (480 +/- 44.7 pg/ml; mean +/- SEM), L. donovani chagasi (295 +/- 7.6 pg/ml), or L. braziliensis (196 +/- 15.7 pg/ml). When TGF-beta was added to cultures of human macrophages infected with L. braziliensis it led to an increase of approximately 50% in parasite numbers as compared with untreated cultures. Exogenous TGF-beta added to macrophage cultures was able to reverse the effect of interferon-gamma in controlling Leishmania growth. Even at 100 IU/ml interferon-gamma the presence of TGF-beta increases the number of intracellular parasites. On the other hand, TNF-alpha at high concentration (100 IU/ml) totally blunts the suppressive effect of TGF-beta. Immunostaining for TGF-beta was observed in the dermis, produced by fibroblasts and occasionally by inflammatory cells in the biopsies from human leishmaniasis lesions, being present in most of the biopsies taken from patients with early cutaneous leishmaniasis (less than 2 months of ulcer development) and in cases of active mucosal leishmaniasis. Taken together these observations suggest an important role for TGF-beta in human leishmaniasis, with its production by infected macrophages being probably related to parasite establishment in the early stages of the disease.

Diabetes mellitus associated with pentamidine isethionate in diffuse cutaneous leishmaniasis

The authors report a case of a male patient from Bacabal, MA with diffuse cutaneous leishmaniasis (DCL), for at least nine years, with 168 lesions on his body. These were tumour-like nodules with some ulceration. He used pentavalent antimonial (glucantime) and an association of gamma interferon plus glucantime with improvement of the lesions but relapsed later. Recently, pentamidine isethionate (pentacarinat) was given a dosage of 4mg/kg/weight/day on alternate days for 20 applications. After 3 months a similar course of 10 application was given 2 times. Later he developed diabetic signs with weight loss of 10kg, polydypsia, polyuria and xerostomia. The lower limbs lesions showed signs of activity. Blood glucose levels normalised and remain like this at moment. Attention is drawn to the fact that pentamidine isethionate should be used as a therapy option with care, obeying rigorous laboratory controls including a glucose tolerance test.

Lymphadenopathy as the first sign of human cutaneous infection by Leishmania braziliensis

This paper describes the presence of transitory lymphadenopathy as an initial sign of cutaneous leishmaniasis, and sometimes the only manifestation of Leishmania braziliensis infection. Ten patients with lymphadenopathy living in an area of L. braziliensis transmission had Leishmania cultivated from their lymph nodes previous to any other manifestation of cutaneous leishmaniasis. Seven of the 10 developed leishmanial ulcers later in the course of infection, whereas lymphadenopathy regressed in three cases and no other sign of infection developed. Results of tests for anti-Leishmania antibodies and an intradermal skin test were positive in four and five patients, respectively, at the time of the diagnosis. The documentation of Leishmania amastigotes in the lymph nodes before any clinical evidence of cutaneous disease indicates that early spread of L. braziliensis from the skin to lymph nodes occurs before a local lesion develops. All medical doctors examining patients coming from endemic areas of leishmaniasis should be aware that lymph node enlargement, even in the absence of a typical ulceration, may be indicative of leishmanial infection and warrants further investigation.