Selective whole-genome amplification reveals population genetics of Leishmania braziliensis directly from patient skin biopsies.

In Brazil, Leishmania braziliensis is the main causative agent of the neglected tropical disease, cutaneous leishmaniasis (CL). CL presents on a spectrum of disease severity with a high rate of treatment failure. Yet the parasite factors that contribute to disease presentation and treatment outcome are not well understood, in part because successfully isolating and culturing parasites from patient lesions remains a major technical challenge. Here we describe the development of selective whole genome amplification (SWGA) for Leishmania and show that this method enables culture-independent analysis of parasite genomes obtained directly from primary patient skin samples, allowing us to circumvent artifacts associated with adaptation to culture. We show that SWGA can be applied to multiple Leishmania species residing in different host species, suggesting that this method is broadly useful in both experimental infection models and clinical studies. SWGA carried out directly on skin biopsies collected from patients in Corte de Pedra, Bahia, Brazil, showed extensive genomic diversity. Finally, as a proof-of-concept, we demonstrated that SWGA data can be integrated with published whole genome data from cultured parasite isolates to identify variants unique to specific geographic regions in Brazil where treatment failure rates are known to be high. SWGA provides a relatively simple method to generate Leishmania genomes directly from patient samples, unlocking the potential to link parasite genetics with host clinical phenotypes.

The contrasting phenotypes of neutrophils during asymptomatic versus symptomatic Leishmania braziliensis infection.

BACKGROUND: The mechanisms that mediate immune protection in individuals with subclinical (SC) or asymptomatic infection with L. braziliensis are largely unknown. Neutrophils (PMNs) have been implicated in progressive symptomatic cutaneous leishmaniasis (CL), but their potential participation in maintenance of subclinical infection is unexplored. The aim of this study was to compare the phenotypic and functional profiles of PMNs in individuals with SC infection versus patients with symptomatic CL due to L. braziliensis. METHODS: Subjects were recruited in the endemic region of Corte de Pedra, Bahia, Brazil. Surface markers to define activation status were characterized by flow cytometry. Functional responses of PMNs including phagocytic capacity, production of oxidative species, and oxidative killing of intracellular parasites were studied in vitro. RESULTS: PMNs from individuals with SC infection displayed a more activated phenotype and greater ability to control the infection than PMNs from patients with CL. In contrast, PMNs from patients with CL exhibited higher expression of HLA-DR and higher production of oxidative species than PMNs from subjects with SC infection. CONCLUSION: PMNs from individuals with SC infection can control the infection more efficiently than PMNs from patients with CL, despite the lower production of oxidants. Our observations suggest that L. braziliensis may evade microbicidal mechanisms of PMNs from patients with CL, contributing to parasite dissemination and the establishment of disease.

Association of Intestinal Helminthiasis with Disseminated Leishmaniasis, Brazil.

Disseminated leishmaniasis is an emerging clinical form of Leishmania braziliensis infection. Evidence shows that co-infection by L. braziliensis and intestinal helminths does not affect clinical manifestations or response to therapy in cutaneous leishmaniasis patients. We evaluated whether co-infection was associated with those aspects in disseminated leishmaniasis patients in Brazil.

Disseminated Leishmaniasis, a Severe Form of Leishmania braziliensis Infection.

Disseminated leishmaniasis (DL) is an emergent severe disease manifesting with multiple lesions. To determine the relationship between immune response and clinical and therapeutic outcomes, we studied 101 DL and 101 cutaneous leishmaniasis (CL) cases and determined cytokines and chemokines in supernatants of mononuclear cells stimulated with leishmania antigen. Patients were treated with meglumine antimoniate (20 mg/kg) for 20 days (CL) or 30 days (DL); 19 DL patients were instead treated with amphotericin B, miltefosine, or miltefosine and meglumine antimoniate. High levels of chemokine ligand 9 were associated with more severe DL. The cure rate for meglumine antimoniate was low for both DL (44%) and CL (60%), but healing time was longer in DL (p = 0.003). The lowest cure rate (22%) was found in DL patients with >100 lesions. However, meglumine antimoniate/miltefosine treatment cured all DL patients who received it; therefore, that combination should be considered as first choice therapy.

Senescence-related genes are associated with the immunopathology signature of American Tegumentary Leishmaniasis lesions and may predict progression to mucosal leishmaniasis.

The American Tegumentary Leishmaniasis (ATL) is caused by protozoans of the genus Leishmania and varies from mild localized cutaneous leishmaniasis (LCL) form to more severe manifestations such as the diffuse cutaneous leishmaniasis (DCL) form and the mucosal leishmaniasis (ML) form. Previously, we demonstrated the accumulation of senescent cells in skin lesions of patients with LCL. Moreover, lesional transcriptomic analyses revealed a robust co-induction of senescence and pro-inflammatory gene signatures, highlighting the critical role of senescent T cells in orchestrating pathology. In this work we hypothesized that senescent cells might operate differently among the ATL spectrum, potentially influencing immunopathological mechanisms and clinical outcome. We analysed previously published RNA-Seq datasets of skin biopsies of healthy subjects and lesional skin from DCL patients, LCL patients and LCL patients that, after treatment, progressed to mucosal leishmaniasis (MLP). Our findings demonstrate a robust presence of a CD8 T cell signature associated with both LCL and MLP lesions. Moreover, both inflammatory and cytotoxic signatures were significantly upregulated, showing a strong increase in MLP and LCL groups, but not DCL. The senescence signature was elevated between LCL and MLP groups, representing the only distinguishable signature of immunopathology between them. Interestingly, our analyses further revealed the senescence signature's capacity to predict progression from LCL to mucosal forms, which was not observed with other signatures. Both the senescence-signature score and specific senescence-associated genes demonstrated an increased capacity to predict mucosal progression, with correct predictions exceeding 97% of cases. Collectively, our findings contribute to a comprehensive understanding of immunosenescence in ATL and suggest that senescence may represent the latest and most important signature of the immunopathogenisis. This highlights its potential value in predicting disease severity.

Evolution of erectile dysfunction in individuals infected with human T-lymphotropic virus 1: a prospective cohort study.

BACKGROUND: Virtually all patients with human T-lymphotropic virus 1 (HTLV-1)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) have some degree of erectile dysfunction (ED), but ED is also found in a large percentage of HTLV-1 carriers. AIM: To evaluate the evolution of ED in individuals infected with HTLV-1 who were followed for up to 15 years. METHODS: This prospective cohort study included men infected with HTLV-1 who had ED, were aged 18 to 70 years, and were followed from January 2004 to December 2019. We used the International Index of Erectile Function-5 (IIEF-5), the Expanded Disability Status Scale and Osame Motor Disability Scale, and the Overactive Bladder Symptom Score (OABSS) to define and stratify ED, neurologic disability, and bladder dysfunction, respectively. OUTCOMES: Time to development of severe ED was the main outcome. RESULTS: We studied 90 men with ED (mean ± SD age, 52.8 ± 9.78 years). At baseline, 42 were carriers, 16 had probable HAM/TSP, and 32 had definite HAM/TSP. IIEF-5 was highest among carriers and lowest in patients with definite HAM/TSP, whereas OABSS was lowest in carriers and highest in patients with definite HAM/TSP. Median (IQR) follow-up was 8.50 years (3.00-12.00). IIEF-5 fell significantly from baseline to last follow-up among carriers and patients with probable and definite HAM/TSP. There was an inverse correlation between the IIEF-5 and the OABSS at last follow-up (r = -0.62, P < .001). In survival analysis, the time to development of severe ED was significantly shorter in patients with definite HAM/TSP when compared with carriers (P = .001) and those with probable HAM/TSP (P = .014). The presence of definite HAM/TSP at baseline was independently associated with the development of severe ED, after adjustment for baseline age and proviral load (hazard ratio, 6.74; P = .008). CLINICAL IMPLICATIONS: Formal assessment of erectile function should be part of the routine clinical assessment of individuals infected with HTLV-1; worsening erectile function should alert clinicians to the possibility of neurologic deterioration. STRENGTHS AND LIMITATIONS: This is the first prospective cohort study to describe the course of ED in men infected with HTLV-1. The small sample size and absence of seronegative controls are limitations. CONCLUSION: ED is a slowly progressive clinical manifestation of HTLV-1 infection, and the degree of neurologic compromise at baseline is the main predictor of time to progression to severe ED.

Immune Response to LinB13, a Lutzomyia Intermedia Salivary Protein Correlates With Disease Severity in Tegumentary Leishmaniasis.

BACKGROUND: We have previously shown that seropositivity to rLinB-13, a salivary protein from Lutzomyia intermedia, predicted sand fly exposure and was associated with increased risk of developing cutaneous leishmaniasis (CL). METHODS: Here, we investigated the cellular immune response to saliva from Lu. intermedia, using rLinB-13 as a surrogate antigen in naturally exposed individuals presenting positive serology to LinB-13. We also investigated the response to rLinB-13 in leishmaniasis patients, displaying active ulcers and positive PCR for Leishmania braziliensis. RESULTS: Peripheral blood mononuclear cells (PBMCs) stimulated in vitro with rLinB-13 secreted elevated levels of interleukin-10 (IL-10), IL-4, IL-1ß, IL-1α, IL-6, and chemokines (CCL3, CCL4, CCL5, and CXCL5). CL and disseminated leishmaniasis (DL) patients displayed a significantly higher immunoglobulin G (IgG) response to rLinB-13 compared with healthy subjects, and anti-rLinB-13 IgG was positively correlated with the number of lesions in DL patients. Positive serology to rLinB-13 was also associated with chemotherapy failure. PBMCs from DL patients stimulated with rLINB-13 secreted significantly higher levels of IL-10 and IL-1ß compared with CL individuals. CONCLUSIONS: In this study, we observed an association between humoral and cellular immune response to the sand fly salivary protein rLinB-13 and disease severity in tegumentary leishmaniasis. This study brings evidence that immunity to rLinB-13 influences disease outcome in L. braziliensis infection and results indicate that positive serology to rLinB-13 IgG can be used as a marker of DL, an emerging and severe form of disease caused by L. braziliensis.

Profile of T and B lymphocytes in individuals resistant to Schistosoma mansoni infection.

The mechanisms involved in the development of resistance to infection/reinfection by Schistosoma mansoni still arouse great interest and controversy. Some authors demonstrate that resistance to infection is attributed to a mixed Th1 and Th2 response and resistance to reinfection after repeated treatments through mechanisms associated with the Th2 response. Through flow cytometry, the phenotypic characterization of B and T lymphocytes in individuals residing in endemic areas with low parasite loads over 10 years was evaluated for the first time in humans. In this study, individuals with low parasite loads for Schistosoma mansoni had a higher proportion of Th1 and Th2 cells. In addition, lymphocytes from these individuals showed a higher degree of expression of costimulatory molecules CD28 and CTLA-4 and regulatory molecules FoxP3 and IL-10, when compared to individuals with high parasite loads. Our data indicate that the control of the parasite load of S. mansoni must be associated with a Th1, Th2, and regulatory response, and that further studies are needed to elucidate the possibility of mechanisms associated with the hyporesponsiveness of lymphocytes from individuals with high parasite loads.

Impaired Th1 Response Is Associated With Therapeutic Failure in Patients With Cutaneous Leishmaniasis Caused by Leishmania braziliensis.

BACKGROUND: Leishmania skin test (LST) evaluates the delayed type hypersensitivity to Leishmania antigens (LA) and has been used for diagnosis of cutaneous leishmaniasis (CL). In CL patients LST is usually positive but a small percentage have negative LST. The aim of this study was to determine the clinical and immunologic features and response to antimony therapy in LST-negative CL patients. METHODS: We compare the clinical presentation, response to therapy, and immune response of CL patients with negative vs positive LST. RESULTS: The clinical presentation was similar in both groups but LST-negative patients had a lower cure rate. In the lesions, LST-negative patients displayed less inflammation and necrosis, and higher frequency of CD8+ T cells. Mononuclear cells from LST-negative patients had a poor T helper 1 cell (Th1) response but levels of interleukin-1ß (IL-1ß), IL-6, IL-17, granzyme B, and metalloproteinase-9 (MMP-9) were similar to the LST-positive group upon stimulation with LA. Leishmania internalization and killing by macrophages were similar in both groups. Cure of disease was associated with restoration of Th1 response. CONCLUSIONS: In LST-negative patients, impaired Th1 response is associated with therapeutic failure. Increased frequency of CD8+ T cells and high production of inflammatory cytokines, granzyme B, and MMP-9 contributes to immunopathology.

Influence of Obesity on Clinical Manifestations and Response to Therapy in Cutaneous Leishmaniasis Caused by Leishmania braziliensis.

BACKGROUND: Cutaneous leishmaniasis (CL) caused by Leishmania braziliensis is characterized by a single ulcer or multiple cutaneous lesions with raised borders. Cure rates <60% are observed in response to meglumine antimoniate therapy. We investigated the impact of obesity on CL clinical presentation and therapeutic response. METHODS: A total of 90 age-matched patients with CL were included (30 obese, 30 overweight, and 30 with normal body mass index [BMI]). CL was diagnosed through documentation of L. braziliensis DNA by polymerase chain reaction or identification of amastigotes in biopsied skin-lesion samples. Serum cytokine levels were determined by chemiluminescence. Antimony therapy with Glucantime (Sanofi-Aventis; 20 mg/kg/day) was administered for 20 days. RESULTS: Obese CL patients may present hypertrophic ulcers rather than typical oval, ulcerated lesions. A direct correlation between BMI and healing time was noted. After 1 course of antimony, cure was achieved in 73% of patients with normal BMI, 37% of overweight subjects, yet just 18% of obese CL patients (P < .01). Obese CL cases additionally presented higher leptin levels than overweight patients or those with normal BMI (P < .05). CONCLUSIONS: Obesity modifies the clinical presentation of CL and host immune response and is associated with greater failure to therapy.

A Double-blind, Randomized Trial to Evaluate Miltefosine and Topical Granulocyte Macrophage Colony-stimulating Factor in the Treatment of Cutaneous Leishmaniasis Caused by Leishmania braziliensis in Brazil.

BACKGROUND: The treatment of cutaneous leishmaniasis (CL) in Brazil using pentavalent antimony (Sbv) is associated with a high rate of failure. Miltefosine has proven efficacy for CL caused by L. braziliensis, with a cure rate (CR) of 75%. A combined treatment with granulocyte macrophage colony-stimulating factor (GM-CSF) and miltefosine could increase CR and decrease healing time. METHODS: A randomized, double-blind clinical trial to evaluate the efficacy of miltefosine combined with topical GM-CSF (M + GM) vs miltefosine and placebo (M + P) vs Sbv in 133 patients with CL caused by L. braziliensis in Bahia, Brazil. RESULTS: The final CR at 180 days after the initiation of treatment was 44.4% in the Sbv group, 76.6% in the M + P group (P = .003 vs Sbv), and 75.6% in the M + GM group (P = .004 vs Sbv). The median healing time for cure was 102 days for the Sbv group and 60 days for both miltefosine groups (P = .0009). During the 6-month follow-up period, 4 relapses were documented: 1 in the Sbv group, 1 in the M + P group, and 2 in the M + GM group. Mild adverse events occurred in 65% of patients from the Sbv group, 76% and 79% from the M + P and M + GM groups respectively. CONCLUSIONS: Miltefosine is more effective than Sbv for the treatment of CL caused by L. braziliensis in Brazil and accelerates the healing time. Association with GM-CSF does not improve therapeutic outcome. CLINICAL TRIALS REGISTRATION: NCT03023111.

A Genome-wide Association Study Identifies SERPINB10, CRLF3, STX7, LAMP3, IFNG-AS1, and KRT80 As Risk Loci Contributing to Cutaneous Leishmaniasis in Brazil.

BACKGROUND: Our goal was to identify genetic risk factors for cutaneous leishmaniasis (CL) caused by Leishmania braziliensis. METHODS: Genotyping 2066 CL cases and 2046 controls using Illumina HumanCoreExomeBeadChips provided data for 4 498 586 imputed single-nucleotide variants (SNVs). A genome-wide association study (GWAS) using linear mixed models took account of genetic diversity/ethnicity/admixture. Post-GWAS positional, expression quantitative trait locus (eQTL) and chromatin interaction mapping was performed in Functional Mapping and Annotation (FUMA). Transcriptional data were compared between lesions and normal skin, and cytokines measured using flow cytometry and Bioplex assay. RESULTS: Positional mapping identified 32 genomic loci associated with CL, none achieving genome-wide significance (P < 5 × 10-8). Lead SNVs at 23 loci occurred at protein coding or noncoding RNA genes, 15 with eQTLs for functionally relevant cells/tissues and/or showing differential expression in lesions. Of these, the 6 most plausible genetic risk loci were SERPINB10 (Pimputed_1000G = 2.67 × 10-6), CRLF3 (Pimputed_1000G = 5.12 × 10-6), STX7 (Pimputed_1000G = 6.06 × 10-6), KRT80 (Pimputed_1000G = 6.58 × 10-6), LAMP3 (Pimputed_1000G = 6.54 × 10-6), and IFNG-AS1 (Pimputed_1000G = 1.32 × 10-5). LAMP3 (Padjusted = 9.25 × 10-12; +6-fold), STX7 (Padjusted = 7.62 × 10-3; +1.3-fold), and CRLF3 (Padjusted = 9.19 × 10-9; +1.97-fold) were expressed more highly in CL biopsies compared to normal skin; KRT80 (Padjusted = 3.07 × 10-8; -3-fold) was lower. Multiple cis-eQTLs across SERPINB10 mapped to chromatin interaction regions of transcriptional/enhancer activity in neutrophils, monocytes, B cells, and hematopoietic stem cells. Those at IFNG-AS1 mapped to transcriptional/enhancer regions in T, natural killer, and B cells. The percentage of peripheral blood CD3+ T cells making antigen-specific interferon-γ differed significantly by IFNG-AS1 genotype. CONCLUSIONS: This first GWAS for CL identified multiple genetic risk loci including a novel lead to understanding CL pathogenesis through regulation of interferon-γ by IFNG antisense RNA 1.

Granzyme B Produced by Natural Killer Cells Enhances Inflammatory Response and Contributes to the Immunopathology of Cutaneous Leishmaniasis.

BACKGROUND: Skin lesions from patients infected with Leishmania braziliensis has been associated with inflammation induced by cytotoxic CD8+ T cells. In addition, CD8+ T cell-mediated cytotoxicity has not been linked to parasite killing. Meanwhile, the cytotoxic role played by natural killer (NK) cells in cutaneous leishmaniasis (CL) remains poorly understood. METHODS: In this study, we observed higher frequencies of NK cells in the peripheral blood of CL patients compared with healthy subjects, and that NK cells expressed more interferon-γ, tumor necrosis factor (TNF), granzyme B, and perforin than CD8+ T cells. RESULTS: We also found that most of the cytotoxic activity in CL lesions was triggered by NK cells, and that the high levels of granzyme B produced in CL lesions was associated with larger lesion size. Furthermore, an in vitro blockade of granzyme B was observed to decrease TNF production. CONCCLUSIONS: Our data, taken together, suggest an important role by NK cells in inducing inflammation in CL, thereby contributing to disease immunopathology.

Neurologic, clinical, and immunologic features in a cohort of HTLV-1 carriers with high proviral loads.

A high proviral load (PVL) is recognized as a risk factor for human T cell leukemia virus-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), but there is a lack of prospective studies evaluating whether or not HTLV-1 carriers with high PVL are at risk of developing HAM/TSP or other HTLV-1-related diseases. Here, we compare the incidence of clinical manifestations and the cytokine levels in 30 HTLV-1 carriers with high (> 50,000 copies/106 PBMC) and an equal number of subjects with low proviral load. Participants were followed for 3 to 16 years (median of 11 years). The PVL, IFN-γ, TNF, and IL-10 levels were quantified at entry and at the end of the follow-up. Among the self-reported symptoms in the initial evaluation, only the presence of paresthesia on the hands was more frequent in the group with high PVL (p < 0.04). The production of IFN-γ was higher in the group with high PVL group (median of 1308 versus 686 pg/ml, p < 0.011) when compared with the control group in the first assessment. There was no difference in the occurrence of urinary symptoms or erectile dysfunction, periodontal disease, Sicca syndrome, and neurologic signs between the two groups during the follow-up. The observation that none of the HTLV-1 carriers with high PVL and with exaggerated inflammatory response progressed to HAM/TSP indicates that other factors in addition to the PVL and an exaggerated immune response are involved in the pathogenesis of HAM/TSP.

A Th2-Type Response Is Associated With Exuberant Lesions in Pregnant Women Infected With Leishmania braziliensis.

Background: Cutaneous leishmaniasis (CL) is characterized by an exaggerated inflammatory response. During pregnancy there is a decreased inflammatory response, and we have shown that pregnant women with CL develop exuberant lesions. Methods: Cytokine production by peripheral blood mononuclear cells and the frequency of cells expressing cytokines in lesions from pregnant and nonpregnant women with CL were evaluated. Results: We observed that CL lesions from pregnant women displayed a more intense cellular infiltrate, associated with an increase in neutrophils and CD4+ cells. While no difference was observed regarding the number of interferon-gamma (IFN-γ)+ cells in lesions from pregnant compared to nonpregnant women with CL, interleukin-10 (IL-10) and IL-4 expression were approximately 3-times higher in lesions in pregnant women. Main sources of IL-4 and IL-10 were CD4+ and CD68+ cells, respectively. Expression of IL-4, but not IFN-γ or IL-10, was positively correlated with the intensity of inflammatory infiltrate in lesions from pregnant women. Conclusions: These results provide evidence of an IL-4-mediated pathology in Leishmania braziliensis-infected pregnant women. These differences in lesion pathogenesis in pregnant and nonpregnant women may open possibilities for new therapies for CL treatment during pregnancy, which are currently lacking.

CD8+ T cell cytotoxicity mediates pathology in the skin by inflammasome activation and IL-1ß production.

Deregulated CD8+ T cell cytotoxicity plays a central role in enhancing disease severity in several conditions. However, we have little understanding of the mechanisms by which immunopathology develops as a consequence of cytotoxicity. Using murine models of inflammation induced by the protozoan parasite leishmania, and data obtained from patients with cutaneous leishmaniasis, we uncovered a previously unrecognized role for NLRP3 inflammasome activation and IL-1ß release as a detrimental consequence of CD8+ T cell-mediated cytotoxicity, ultimately resulting in chronic inflammation. Critically, pharmacological blockade of NLRP3 or IL-1ß significantly ameliorated the CD8+ T cell-driven immunopathology in leishmania-infected mice. Confirming the relevance of these findings to human leishmaniasis, blockade of the NLRP3 inflammasome in skin biopsies from leishmania-infected patients prevented IL-1ß release. Thus, these studies link CD8+ T cell cytotoxicity with inflammasome activation and reveal novel avenues of treatment for cutaneous leishmaniasis, as well as other of diseases where CD8+ T cell-mediated cytotoxicity induces pathology.

Impaired immunoregulatory network of the CD4 T lymphocytes in refractory asthma.

BACKGROUND: The immunopathogenesis of severe asthma has been associated with an inefficient regulatory response. There are a few studies about the CD4 T cells profile among individuals with severe asthma refractory to treatment. OBJECTIVE: To evaluate the CD4 T lymphocyte profile from individuals with severe asthma according to their response to treatment, relating to their atopy status and age of asthma onset. METHODS: We evaluated nineteen individuals with severe asthma refractory to treatment (SAR), 21 with well-controlled or partly controlled severe asthma (CSA) and 23 with mild-to-moderate asthma (MMA). Lymphocytes were obtained from PBMC, and the frequency of expression of different molecules in this population was assessed using the flow cytometry. RESULTS: We observed the frequency of CD4+ IFN-γ+ T cells was higher in atopic individuals with SAR than with CSA. In addition, among the atopic and early-onset asthma (EOA), the frequency of CD4+ CTLA-4+ T cells was lower in the SAR group than the CSA group. In relation to non-atopic and late-onset asthma (LOA) phenotypes, we noted the frequency of CD4+ FoxP3+ T cells was lower in individuals with SAR than with CSA. We also observed among the LOA patients, the frequency of CD4+ TGF-ß+ T cells was decreased in SAR group than the in CSA group. CONCLUSION AND CLINICAL RELEVANCE: Our data suggest that refractoriness to treatment in asthma is associated with a lower expression of distinct regulatory molecules by CD4 T cells between those who are atopic and have EOA and those who are non-atopic and have LOA. Thus, these results may contribute to the identification of new regulatory strategies to treat asthma according to their phenotypes.

Leishmania braziliensis isolated from disseminated leishmaniasis patients downmodulate neutrophil function.

AIMS: The polymorphism observed in Leishmania braziliensis is associated with different clinical forms of leishmaniasis. Neutrophils (PMNs) participate in the pathogenesis of leishmania infection, and here, we evaluate neutrophil function after infection with isolates of L. braziliensis from cutaneous leishmaniasis (CL) or disseminated leishmaniasis (DL) patients. METHODS AND RESULTS: Neutrophils from 30 healthy subjects (HS) were infected with isolates of L. (V.) braziliensis obtained from three CL and three DL patients. They were infected at the ratio of 3:1 parasites per neutrophil, and leishmania uptake was evaluated by microscopy. The neutrophil activation markers and oxidative burst by expression of dihidrorhodamine (DHR) were evaluated by flow cytometry and cytokine production by ELISA. The frequency of infected cells and the number of amastigotes were higher in neutrophils infected with CL isolates compared to DL isolates (P < 0.05). The DHR and CD66b expression after infection with DL isolate was lower than with CL isolates. There was no difference regarding chemokine production. CONCLUSION: The L. (V.) braziliensis isolates of DL induced lower respiratory burst and neutrophils activation markers compared with CL isolates which may contribute to parasite survival and dissemination in DL patients.

Characterization of memory T cells in individuals resistant to Schistosoma mansoni infection.

Schistosomiasis affects about 240 million people worldwide and is estimated that about 700 million people live in areas at risk of infection. In the context of immune response associated with infection by Schistosoma mansoni, the role of memory T cells is not well understood. AIM: To evaluate the frequency of memory CD4+ and CD8+ T cells from individuals resistant and susceptible to Schistosoma mansoni infection. METHODS AND RESULTS: We selected individuals with low (resistant) and high (susceptible) parasite burden using databases generated during previous studies carried out in the same endemic area. The cell surface markers were performed using flow cytometry. In this study, the resistant individuals showed an increase in the CD4+ memory T-cell pool associated with an increase in the central memory cell (TCM) and a decrease in the effector memory cell (TEM ). Individuals susceptible to infection had higher frequencies of effector memory cells compared to resistant individuals. CONCLUSIONS: These data suggest that resistance to S mansoni infection may be associated with an increase in the number of CD4+ memory T cells and susceptibility to infection is associated with a decrease in the central memory cell as well as high proportions of effector memory cells.

Early Cutaneous Leishmaniasis Patients Infected With Leishmania braziliensis Express Increased Inflammatory Responses After Antimony Therapy.

Background: Early cutaneous leishmaniasis (ECL) is characterized by a nonulcerated papular lesion and illness duration less than 30 days. Approximately 4 weeks later, the cutaneous leishmaniasis (CL) ulcers appear. We were surprised to find that failure after antimony therapy (Sb5) is higher in ECL than CL. We hypothesize that the inflammatory response in ECL patients may increase during Sb5 therapy, which leads to treatment failure. Methods: A cohort of 44 ECL patients infected by Leishmania braziliensis was established to evaluate the response to Sb5 and to compare immunologic responses in ECL patients with CL and healthy subjects. Results: A hierarchical clustering based on cytokine levels showed a weak positive correlation between proinflammatory cytokine levels and those patients that failed Sb5 treatment. Although Sb5 therapy decreased interferon-γ and tumor necrosis factor levels in CL patients, we were surprised to find that an increase in these cytokines was observed in ECL patients. Moreover, interleukin (IL)-10 was less able to down-modulate immune responses in ECL. Conclusions: The enhanced production of proinflammatory cytokines, due in part to the decreased ability of IL-10 to down-modulate immune response during therapy in ECL, promotes the development and persistence of leishmania ulcer despite antimony therapy.