American cutaneous leishmaniasis: In situ immune response of patients with recent and late lesions

Is There Any Difference in the In Situ Immune Response in Active Localized Cutaneous Leishmaniasis That Respond Well or Poorly to Meglumine Antimoniate Treatment or Spontaneously Heal?

Localized cutaneous leishmaniasis caused by Leishmania braziliensis can either respond well or poorly to the treatment or heal spontaneously; It seems to be dependent on the parasite and/or host factors, but the mechanisms are not fully understood. We evaluated the in situ immune response in eighty-two active lesions from fifty-eight patients prior to treatment classified as early spontaneous regression (SRL-n = 14); treatment responders (GRL-n = 20); and non-responders (before first treatment/relapse, PRL1/PRL2-n = 24 each). Immunohistochemistry was used to identify cell/functional markers which were correlated with the clinical characteristics. PRL showed significant differences in lesion number/size, clinical evolution, and positive parasitological examinations when compared with the other groups. SRL presented a more efficient immune response than GRL and PRL, with higher IFN-γ/NOS2 and a lower percentage of macrophages, neutrophils, NK, B cells, and Ki-67+ cells. Compared to SRL, PRL had fewer CD4+ Tcells and more CD163+ macrophages. PRL1 had more CD68+ macrophages and Ki-67+ cells but less IFN-γ than GRL. PRL present a less efficient immune profile, which could explain the poor treatment response, while SRL had a more balanced immune response profile for lesion healing. Altogether, these evaluations suggest a differentiated profile of the organization of the inflammatory process for lesions of different tegumentary leishmaniasis evolution.

Quality parameters for RNA preparations from biopsies of ulcerated human skin

Background: Obtaining high quality RNA from skin biopsies is complex due the physical composition and high content of nucleases of this tissue. This becomes particularly challenging when using compromised skin samples with necrotic, inflammed or damaged areas, such as those from patients suffering skin conditions, which affect more than 900 million people annually. We evaluated the impact of the biopsy size and tissue preservation method on the quality and quantity of RNA extracts. Methods: Skin lesion biopsies were obtained from patients with cutaneous leishmaniasis (CL). Biopsy specimens of 2 mm (n = 10) and 3 mm (n = 59) were preserved in Allprotect® reagent, and 4 mm biopsies in OCT (n = 54). Quality parameters were evaluated using Nanodrop and Bioanalyzer. The informativeness of the extracted samples for downstream analyses was evaluated using RT-qPCR and RNA-Seq. Results: The success rate, based on quality parameters of RNA extraction from tissue biopsies stored in OCT and 2 mm biopsies stored in Allprotect®, was 56% (30/54) and 30% (3/10), respectively. For 3 mm skin biopsies stored in Allprotect® was 93% (55/59). RNA preparations from 3 mm-Allprotect® biopsies had an average RIN of 7.2 ± 0.7, and their integrity was not impacted by sample storage time (up to 200 days at -20°C). RNA products were appropriate for qRT-PCR and RNA-seq. Based on these results, we propose a standardized method for RNA extraction from disrupted skin samples. This protocol was validated with lesion biopsies from CL patients (n = 30), having a success rate of 100%. Conclusions: Our results indicate that a biopsy size of 3 mm in diameter and preservation in Allprotect® for up to 200 days at -20°C, are best to obtain high quality RNA preparations from ulcerated skin lesion biopsy samples.

In situ expression of Th17 immunologic mediators in American cutaneous leishmaniasis caused by Leishmania (V.) braziliensis and Leishmania (L.) amazonensis in the Brazilian Amazon

American cutaneous leishmaniasis (ACL) presents a wide spectrum of clinical and immunopathological manifestations. In Brazil, Leishmania (L.) amazonensis[La] and Leishmania(V.)braziliensis[Lb] show the highest pathogenic potential for humans causing different clinical forms: localized cutaneous leishmaniasis (LCL : Lb/La), anergic diffuse cutaneous leishmaniasis (ADCL : La) and mucocutaneous leishmaniasis (MCL : Lb). ADCL and MCL are the most severe forms and infection leads to a cellular immune response at the hyposensitivity and hypersensitivity poles. Th17-cells are involved in the ACL pathogenesis, are derived from naïve TCD4+ cells regulated by RORγt, differentiate in presence of IL-6, TGF-β, IL- 1β, IL-23 and express IL-17. Aim of this study was to characterize the cellular immune response mediated by Th17-profile cells through in situ determination of the expression of RORγt, IL-17, IL-6, TGF-β, IL-1β, and IL-23 in the ACL clinical-immunopathological spectrum caused by L.(L.)amazonensis and L.(V.)braziliensis. Biopsies of skin and mucosal lesions from forty patients including ADCL(n=8), LCL[La](n=17), LCL[Lb](n=9) and MCL(n=6), were examined by immunohistochemistry. The immunostained cells density (cells/mm2) was determined in image analysis system using AxionVision 4.8 software (Zeiss). As the disease evolution time (DET) was different among ACL patients, the effect of DET on the expression of immunological markers was evaluated in different clinical forms and histopathological changes, using ANCOVA. Our results showed significantly increased expression of RORγt, IL-17, IL-6, IL-1β and IL-23 in patients with ACL polar forms (ADCL and MCL); higher TGF-β expression was found in ADCL. DET influenced the expression of RORγt and IL-6 in: clinical forms of ACL and in categories of parasitism. DET also affected the production of RORγt, IL-17, IL-6, TGF-β and IL-1β in types of inflammatory infiltrate, evidencing that DET had effect on the expression of Th17 profile cytokines in ACL. Together, the expression of immunological mediators of Th17 profile in the ACL spectrum, as well as the DET effect, demonstrate the participation of this cell lineage in the immunopathogenesis of ACL, mainly in the polar and more severe forms of ACL spectrum. The dubious role played by Th17-cells may favors immune response suppression and parasitic persistence in ADCL, while in MCL it contributes to an exacerbated immune response and parasite scarcity.

Quality parameters for RNA preparations from biopsies of ulcerated human skin

Background: Obtaining high quality RNA from skin biopsies is complex due the physical composition and high content of nucleases of this tissue. This becomes particularly challenging when using compromised skin samples with necrotic, inflammed or damaged areas, such as those from patients suffering skin conditions, which affect more than 900 million people annually. We evaluated the impact of the biopsy size and tissue preservation method on the quality and quantity of RNA extracts. Methods: Skin lesion biopsies were obtained from patients with cutaneous leishmaniasis (CL). Biopsy specimens of 2 mm (n = 10) and 3 mm (n = 59) were preserved in Allprotect® reagent, and 4 mm biopsies in OCT (n = 54). Quality parameters were evaluated using Nanodrop and Bioanalyzer. The informativeness of the extracted samples for downstream analyses was evaluated using RT-qPCR and RNA-Seq. Results: The success rate, based on quality parameters of RNA extraction from tissue biopsies stored in OCT and 2 mm biopsies stored in Allprotect®, was 56% (30/54) and 30% (3/10), respectively. For 3 mm skin biopsies stored in Allprotect® was 93% (55/59). RNA preparations from 3 mm-Allprotect® biopsies had an average RIN of 7.2 ± 0.7, and their integrity was not impacted by sample storage time (up to 200 days at -20°C). RNA products were appropriate for qRT-PCR and RNA-seq. Based on these results, we propose a standardized method for RNA extraction from disrupted skin samples. This protocol was validated with lesion biopsies from CL patients (n = 30), having a success rate of 100%. Conclusions: Our results indicate that a biopsy size of 3 mm in diameter and preservation in Allprotect® for up to 200 days at -20°C, are best to obtain high quality RNA preparations from ulcerated skin lesion biopsy samples.

Identification of Leishmania infantum and Leishmania braziliensis in captive primates from a zoo in Brazil

Wild nonhuman primates (NHP) are considered natural hosts of a protozoan parasite from the genus Leishmania, the etiological agent of leishmaniasis. It is important to study the population of this infectious agent in zoo animals to establish surveillance and control mechanisms in Sorocaba through the application of a One Health approach, this is where human-animal-environment health and disease interface and can aid in the protection of endangered species. This study aimed to identify Leishmania infantum and Leishmania braziliensis in NHP living in a city where leishmaniasis is endemic. DNA was extracted from 48 NHP and analyzed using polymerase chain reaction primers that are specific for the species L. infantum and L. braziliensis. The results of our research revealed the first report of L. infantum and L. braziliensis naturally infecting primates at Sorocaba zoo. One primate from the species Plecturocebus vieirai was positive for L. infantum and five primates (four Alouatta caraya and one Ateles chamek) were positive for L. braziliensis. This indicates a possible role of these animals on the maintenance of these parasites.

Leishmania Parasites Drive PD-L1 Expression in Mice and Human Neutrophils With Suppressor Capacity

Neutrophils play an important role in the outcome of leishmaniasis, contributing either to exacerbating or controlling the progression of infection, a dual effect whose underlying mechanisms are not clear. We recently reported that CD4⁺ and CD8⁺ T cells, and dendritic cells of Leishmania amazonensis-infected mice present high expression of PD-1 and PD-L1, respectively. Given that the PD-1/PD-L1 interaction may promote cellular dysfunction, and that neutrophils could interact with T cells during infection, we investigated here the levels of PD-L1 in neutrophils exposed to Leishmania parasites. We found that both, promastigotes and amastigotes of L. amazonensis induced the expression of PD-L1 in the human and murine neutrophils that internalized these parasites in vitro. PD-L1-expressing neutrophils were also observed in the ear lesions and the draining lymph nodes of L. amazonensis-infected mice, assessed through cell cytometry and intravital microscopy. Moreover, expression of PD-L1 progressively increased in neutrophils from ear lesions as the disease evolved to the chronic phase. Co-culture of infected neutrophils with in vitro activated CD8⁺ T cells inhibits IFN-γ production by a mechanism dependent on PD-1 and PD-L1. Importantly, we demonstrated that in vitro infection of human neutrophils by L braziliensis induced PD-L1⁺ expression and also PD-L1⁺ neutrophils were detected in the lesions of patients with cutaneous leishmaniasis. Taken together, these findings suggest that the Leishmania parasite increases the expression of PD-L1 in neutrophils with suppressor capacity, which could favor the parasite survival through impairing the immune response.

Immunization with extracellular vesicles excreted by Toxoplasma gondii confers protection in murine infection, activating cellular and humoral responses

The study aim was to analyze whether microvesicles and exosomes, named extracellular vesicles (EVs), purified from Toxoplasma gondii are able to stimulate the protective immunity of experimental mice when administered, as challenge, a highly virulent strain. EVs excreted from T. gondii tachyzoites (RH strain) were purified by chromatography and used for immunization assays in inbred mouse groups (EV-IM). Chronic infected (CHR) and naive (NI) mice were used as control groups, since the immune response is well known. After immunizations, experimental groups were challenged with 100 tachyzoites. Next, parasitemias were determined by real-time PCR (qPCR), and survival levels were evaluated daily. The humoral response was analyzed by detection of IgM, IgG, IgG1 and IgG2a, and opsonization experiments. The cellular response was evaluated in situ by immunohistochemistry on IFN-γ, IL-10, TNF-α and IL-17 expression in cells of five organs (brain, heart, liver, spleen and skeletal muscles). EV immunization reduced parasitemia and increased the survival index in two mouse lineages (A/Sn and BALB/c) infected with a lethal T. gondii strain. EV-IM mice had higher IgG1 levels than IgM or IgG2a. IgGs purified from sera of EV-IM mice were able to opsonize tachyzoites (RH strain), and mice that received these parasites had lower parasitemias, and mortality was delayed 48 h, compared with the same results from those receiving parasites opsonized with IgG purified from NI mice. Brain and spleen cells from EV-IM mice more highly expressed IFN-γ, IL-10 and TNF-α. In conclusion, EV-immunization was capable of inducing immune protection, eliciting high production of IgG1, IFN-γ, IL-10 and TNF-α.

In-situ immune profile of polymorphic vs. macular Indian Post Kala-azar dermal leishmaniasis

Post Kala-azar Dermal Leishmaniasis (PKDL), a sequel of apparently cured Visceral Leishmaniasis presents in South Asia with papulonodular (polymorphic) or hypomelanotic lesions (macular). Till date, the polymorphic variant was considered predominant, constituting 85–90%. However, following active-case surveillance, the proportion of macular PKDL has increased substantially to nearly 50%, necessitating an in-depth analysis of this variant. Accordingly, this study aimed to delineate the cellular infiltrate in macular vis-à-vis polymorphic PKDL. To study the overall histopathology, hematoxylin and eosin staining was performed on lesional sections and phenotyping by immunohistochemistry done in terms of dendritic cells (CD1a), macrophages (CD68), HLA-DR, T-cells (CD8, CD4), B-cells (CD20) and Ki67 along with assessment of the status of circulating homing markers CCL2, CCL7 and CXCL13. In polymorphic cases (n = 20), the cellular infiltration was substantial, whereas in macular lesions (n = 20) it was mild and patchy with relative sparing of the reticular dermis. Although parasite DNA was identified in both variants by ITS-1 PCR, the parasite load was significantly higher in the polymorphic variant and Leishman-Donovan bodies were notably minimally present in macular cases. Both variants demonstrated a decrease in CD1a⁺ dendritic cells, HLA-DR expression and CD4⁺ T-cells. In macular cases, the proportion of CD68⁺ macrophages, CD8⁺ T-cells and CD20⁺ B-cells was 4.6 fold, 17.0 fold and 1.6 fold lower than polymorphic cases. The absence of Ki67 positivity and increased levels of chemoattractants suggested dermal homing of these cellular subsets. Taken together, as compared to the polymorphic variant, patients with macular PKDL demonstrated a lower parasite load along with a lesser degree of cellular infiltration, suggesting differences in host-pathogen interactions, which in turn can impact on their disease transmitting potential and responses to chemotherapy.

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Comparative analysis of immunopathology of polymorphic vs. macular PKDL.

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Dense lymphohistiocytic infiltrate in polymorphic PKDL.

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Mild and patchy cellular infiltration in macular PKDL with minimal Leishman Donovan bodies.

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Decreased presence of CD1a, HLA-DR and CD4⁺ T-cells in both variants.

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The presence of CD8⁺, CD68⁺and CD20⁺ cells in polymorphic>>>macular PKDL.

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.

Circulating Senescent T Cells Are Linked to Systemic Inflammation and Lesion Size During Human Cutaneous Leishmaniasis

Leishmania (Viannia) braziliensis induces American tegumentary leishmaniasis that ranges in severity from the milder form, cutaneous (CL) to severe disseminated cutaneous leishmaniasis. Patients with CL develop a cell-mediated Th1 immune response accompanied by production of inflammatory cytokines, which contribute to parasite control and pathogenesis of disease. Here, we describe the accumulation of circulating T cells with multiple features of telomere dependent-senescence including elevated expression of CD57, KLRG-1, and γH2AX that have short telomeres and low hTERT expression during cutaneous L. braziliensis infection. This expanded population of T cells was found within the CD45RA⁺CD27^- (EMRA) subset and produced high levels of inflammatory cytokines, analogous to the senescence-associated secretory profile (SASP) that has been described in senescent non-lymphoid cells. There was a significant correlation between the accumulation of these cells and the extent of systemic inflammation, suggesting that they are involved in the inflammatory response in this disease. Furthermore, these cells expressed high level of the skin homing receptor CLA and there was a highly significant correlation between the number of these cells in the circulation and the size of the Leishmania-induced lesions in the skin. Collectively our results suggest that extensive activation during the early stages of leishmaniasis drives the senescence of T cells with the propensity to home to the skin. The senescence-related inflammatory cytokine secretion by these cells may control the infection but also contribute to the immunopathology in the disease.

Gene expression profile of cytokines produced in biopsies from patients with American cutaneous leishmaniasis

American cutaneous leishmaniasis (ACL) causes a local inflammatory process, inducing expression of several cytokine genes. Particularly, IFN-γ can predict to disease susceptibility. Based in these data, this study was aimed to investigate the gene expression profile of IFN-γ, IL-10, IL-27, TNF-γ, TGF-β and IL-6 produced in biopsies from ACL patients; and whether the gene expression profile of IFN-γ could determine the disease evolution. Gene expression of 6 cytokines was investigated in 40 formalin-fixed paraffin embedded (FFPE) biopsies from patients with cutaneous leishmaniosis (CL); and 10 FFPE biopsies from patients with mucosal leishmaniasis (ML) (control). All 50 patients were infected with Leishmania (Viannia) braziliensis. Gene expression was determined by qPCR; and a normal control group was used for calculations (5 normal biopsies). Values were expressed as Relative Quantification (RQ). The 40 CL patients were classified into 2 groups. CLlowIFN-γ, 35 patients with RQ for IFN-γ below 100; and CLhighIFN-γ, 5 (12.5%) patients with RQ above 100. Significant increase of mRNA levels of IFN-γ, IL-10 and IL-27 was shown in CLhighIFN-γ group when compared with CLlowIFN-γ and ML groups. TNF-α levels in CLlowIFN-γ group were higher than CLhighIFN-γ and ML groups. TGF-β and IL-6 were similar in 3 groups. Comparison of cytokine expression/group showed that CLlowIFN-γ group had an equilibrium between the cytokines analyzed. In ML group, IFN-γ was over-expressed; but in CLhighIFN-γ group, besides IFN-γ, IL-27 was also over-expressed. The immune response to Leishmania induces to identification of some markers, which can be determined by analysis by gene expression of cytokines produced in biopsies.

First case report of atypical disseminated cutaneous leishmaniasis in an opium abuser in Iran

Leishmaniasis is a worldwide tropical infectious disease caused by different species of intracellular protozoa parasites of the genus Leishmania . Herein, we report a 78-year-old man with unusual diffuse cutaneous leishmaniasis (DCL) who had a history of opium abuse and chronic obstructive pulmonary disease (COPD). He had multiple papular, crusted and severely ulcerated lesions extended to his arm and chest. Direct smears and skin punch biopsy of the lesions were suggestive of leishmaniasis. Parasite DNA was amplified from ulcers, and identified as Leishmania major by PCR-RFLP, confirmed by sequencing analyses. The aim of the current study was to bring to attention this atypical form of disease in CL endemic countries. Thus, this is the first case of DCL in an opium abuser with COPD due to L. major in Northeastern Iran indicating that atypical and extensive forms of CL (DCL) owing to L. major are increasing in Iran.

Arginase activity of Leishmania isolated from patients with cutaneous leishmaniasis

Cutaneous leishmaniasis (CL) is one of the most important vector-borne parasitic diseases, highly endemic in Iran, and its prevalence is increasing all over the country. Arginase (ARG) activity in isolated Leishmania parasites from CL patients is yet to be explored. This study aimed to compare the ARG activity of isolated Leishmania promastigotes from CL patients with a standard strain of Leishmania major and its influences on the disease pathogenesis. We recruited 16 confirmed CL patients from Qom Province, in central Iran; after detection of Leishmania species using PCR-RFLP, we assessed the levels of ARG in the isolated promastigotes and determined the parasites' growth rate. Only L. major was identified from CL patients. The level of ARG activity in the isolated Leishmania promastigotes from CL patients was significantly higher than that obtained from the standard strain of L. major. No significant correlations between ARG activity and lesion size, number or duration were observed; in contrast, a significant negative correlation was seen between ARG level and Leishmania' growth rate. The obtained results suggest that increased ARG expression and activity in the isolated Leishmania promastigotes might contribute to the higher parasite infectivity and play a major role in the pathogenicity of the CL.