DC-SIGN receptor is expressed by cells from cutaneous leishmaniasis lesions and differentially binds to Leishmania (Viannia) braziliensis and L. (Leishmania) amazonensis promastigotes.

BACKGROUND: Dendritic cells (DCs) specific intercellular adhesion molecule (ICAM)-3-grabbing non integrin receptor (DC-SIGN) binds to subgenera Leishmania promastigotes mediating its interaction with DC and neutrophils, potentially influencing the infection outcome. OBJECTIVES: In this work, we investigated whether DC-SIGN receptor is expressed in cells from cutaneous leishmaniasis (CL) lesions as well as the in vitro binding pattern of Leishmania (Viannia) braziliensis (Lb) and L. (L.) amazonensis (La) promastigotes. METHODS: DC-SIGN receptor was labeled by immunohistochemistry in cryopreserved CL tissue fragments. In vitro binding assay with CFSE-labeled Lb or La promastigotes and RAJI-transfecting cells expressing DC-SIGN (DC-SIGNPOS) or mock-transfected (DC-SIGNNEG) were monitored by flow cytometry at 2 h, 24 h and 48 h in co-culture. RESULTS: In CL lesion infiltrate, DC-SIGNPOS cells were present in the dermis and near the epidermis. Both Lb and La bind to DC-SIGNPOS cells, while binding to DC-SIGNNEG was low. La showed precocious and higher affinity to DC-SIGNhi population than to DC-SIGNlow, while Lb binding was similar in these populations. CONCLUSION: Our results demonstrate that DC-SIGN receptor is present in L. braziliensis CL lesions and interact with Lb promastigotes. Moreover, the differences in the binding pattern to Lb and La suggest DC-SIGN can influence in a difference way the intake of the parasites at the first hours after Leishmania infection. These results raise the hypothesis that DC-SIGN receptor could participate in the immunopathogenesis of American tegumentary leishmaniasis accounting for the differences in the outcome of the Leishmania spp. infection.

Dual Role of Insulin-Like Growth Factor (IGF)-I in American Tegumentary Leishmaniasis.

BACKGROUND: Cytokines and growth factors involved in the tissue inflammatory process influence the outcome of Leishmania infection. Insulin-like growth factor (IGF-I) constitutively present in the skin may participate in the inflammatory process and parasite-host interaction. Previous work has shown that preincubation of Leishmania (Leishmania) amazonensis with recombinant IGF-I induces accelerated lesion development. However, in human cutaneous leishmaniasis (CL) pathogenesis, it is more relevant to the persistent inflammatory process than progressive parasite proliferation. In this context, we aimed to investigate whether IGF-I was present in the CL lesions and if this factor may influence the lesions' development acting on parasite growth and/or on the inflammatory/healing process. Methodology. Fifty-one CL patients' skin lesion samples from endemic area of L. (Viannia) braziliensis infection were submitted to histopathological analysis and searched for Leishmania and IGF-I expression by immunohistochemistry. RESULTS: In human CL lesions, IGF-I was observed preferentially in the late lesion (more than 90 days), and the percentage of positive area for IGF-I was positively correlated with duration of illness (r = 0.42, P < 0.05). IGF-I was highly expressed in the inflammatory infiltrate of CL lesions from patients evolving with good response to therapy (2.8% ± 2.1%; median = 2.1%; n = 18) than poor responders (1.3% ± 1.1%; median: 1.05%; n = 6; P < 0.05). CONCLUSIONS: It is the first time that IGF-I was detected in lesions of infectious cutaneous disease, specifically in American tegumentary leishmaniasis. IGF-I was related to chronicity and good response to treatment. We may relate this finding to the efficient anti-inflammatory response and the known action of IGF-I in wound repair. The present data highlight the importance of searching nonspecific factors besides adaptive immune elements in the study of leishmaniasis' pathogenesis.

DC-SIGN receptor is expressed by cells from cutaneous leishmaniasis lesions and differentially binds to Leishmania (Viannia) braziliensis and L. (Leishmania) amazonensis promastigotes

BACKGROUND Dendritic cells (DCs) specific intercellular adhesion molecule (ICAM)-3-grabbing non integrin receptor (DC-SIGN) binds to subgenera Leishmania promastigotes mediating its interaction with DC and neutrophils, potentially influencing the infection outcome. OBJECTIVES In this work, we investigated whether DC-SIGN receptor is expressed in cells from cutaneous leishmaniasis (CL) lesions as well as the in vitro binding pattern of Leishmania (Viannia) braziliensis (Lb) and L. (L.) amazonensis (La) promastigotes. METHODS DC-SIGN receptor was labeled by immunohistochemistry in cryopreserved CL tissue fragments. In vitro binding assay with CFSE-labeled Lb or La promastigotes and RAJI-transfecting cells expressing DC-SIGN (DC-SIGNPOS) or mock-transfected (DC-SIGNNEG) were monitored by flow cytometry at 2 h, 24 h and 48 h in co-culture. RESULTS In CL lesion infiltrate, DC-SIGNPOS cells were present in the dermis and near the epidermis. Both Lb and La bind to DC-SIGNPOS cells, while binding to DC-SIGNNEG was low. La showed precocious and higher affinity to DC-SIGNhi population than to DC-SIGNlow, while Lb binding was similar in these populations. CONCLUSION Our results demonstrate that DC-SIGN receptor is present in L. braziliensis CL lesions and interact with Lb promastigotes. Moreover, the differences in the binding pattern to Lb and La suggest DC-SIGN can influence in a difference way the intake of the parasites at the first hours after Leishmania infection. These results raise the hypothesis that DC-SIGN receptor could participate in the immunopathogenesis of American tegumentary leishmaniasis accounting for the differences in the outcome of the Leishmania spp. infection.

Is Leishmania (Viannia) braziliensis parasite load associated with disease pathogenesis?

BACKGROUND: Leishmania (Viannia) braziliensis is the main etiological agent of tegumentary leishmaniasis in the Americas. Parasite molecular diversity and host immune status contribute to extensive variations in its clinical presentation within endemic areas of Brazil. Pentavalent antimonials have been used for more than 60 years as the first-line drug for all cases, despite the potential for severe side effects and refractoriness. In Rio de Janeiro, Brazil, most L. (V.) braziliensis infections are benign with a scarcity of parasites, although metastasis and refractory infections can arise. In this scenario, the use of novel molecular tools can be useful for diagnosis and to assess tissue parasitism, and is of benefit to clinical and therapeutic management. METHODS: In this study, parasite load was assessed by real-time PCR based on the leishmanial small subunit ribosomal RNA gene. RESULTS AND CONCLUSION: The data revealed a tendency to higher tissue parasitism in the skin compared to mucous lesion sites and a reduction with disease progression. Parasite load was lower in poor compared to good responders to antimonials, and was also reduced in recurrent lesions compared to primary ones. However, parasite load became higher with sequential relapses, pointing to an immune system inability to control the infection. Therefore the parasite burden does not seem to be a good predictor of disease progression.

An alternative antimonial schedule to be used in cutaneous leishmaniasis when high doses of antimony are undesirable.

Despite more than half a century of use in leishmaniasis, antimony therapy still presents serious problems concerning dosage and toxicity. Low and high doses have been shown to be equally effective. In this paper, the feasibility of injecting one ampoule of meglumine antimoniate intramuscularly every other day until clinical cure is demonstrated, while studying a series of 40 cutaneous leishmaniasis cases. Total dose used varied from 1,822.5 to 12,150 mg of pentavalent antimony and total time of treatment varied from 3 to 10 weeks, with 86% efficacy. Thirty-six out of the 40 patients are still on follow-up with a mean time of 10.7 +/- 7 months and a median of 9 months. No relapse or mucosal lesions have been noted so far. The schedule showed good tolerance and easy application and its efficacy was comparable to the officially recommended WHO schedule. Therefore, such a schedule represents a valuable alternative for the cases with high toxicicity to antimony or daily injections are an obstacle to the treatment.

Successful therapeutic response of resistant cases of mucocutaneous leishmaniasis to a very low dose of antimony.

Two mucocutaneous leishmaniasis cases resistant to therapy are reported here. After the failure of initial therapies (antimony, amphotericin B and/or pentamidine) patients received a low-dose schedule: one ampoule of meglumine antimoniate (405 mg of pentavalent antimony [Sb v]) by intramuscular injection, three times a week until complete healing of the lesions. One patient was cured with a total of 30 ampoules in 10 weeks and the other received 36 ampoules in 12 weeks. Both remain clinically cured after one year of follow-up.

MMP-9 activity is induced by Leishmania braziliensis infection and correlates with mucosal leishmaniasis.

Infection of humans with Leishmania braziliensis typically results in localized cutaneous leishmaniasis (LCL). Rarely, after months or years of apparent clinical cure, some patients develop the destructive mucosal leishmaniasis (ML). ML results from L. braziliensis dissemination, probably via phagocytic cells. As the preferred cells for Leishmania spp. colonization, macrophages are critical to infection control, and may contribute to parasite dissemination. However, the host factors that determine this outcome are unknown. Matrix metalloproteinase 9 (MMP-9) is known to be important for immune cell migration, macrophage recruitment, and effective granuloma formation. Moreover, MMP-9 has been involved in Mycobacterium tuberculosis dissemination. Here, we demonstrate that in vitro infection of human macrophages with L. braziliensis increased the secretion and activation of MMP-9. We also demonstrate that macrophages from healthy cured individuals with previous history of ML had increased MMP-9 activity compared to LCL cured individuals. These findings may represent a fundamental difference in host innate immunity that could contribute to the clinical leishmaniasis presentation.

Cutaneous mucormycosis in a young, immunocompetent girl.

We report a case of cutaneous mucormycosis in a healthy, immunocompetent young girl (age 14 years). The patient had a 5-year history of a slowly enlarging, erythematous plaque with slight elevated, scaling, circinate borders on the right thigh. Histopathology showed a granulomatous infiltrate with broad, pale, non-septate hyphae. Mycological study identified Mucor hiemalis (Wehmer).

Genetic polymorphism and molecular epidemiology of Leishmania (Viannia) braziliensis from different hosts and geographic areas in Brazil.

Numerical zymotaxonomy and variability of the internal transcribed spacers (ITS) between the small and large subunits of the rRNA genes were used to examine strain variation and relationships in natural populations of Leishmania (Viannia) braziliensis. A total of 101 strains from distinct hosts and Brazilian geographic regions were assigned to 15 zymodemes clustered in two major genetic groups. The great number of isolates (48.5%) placed in zymodeme IOC/Z-27 were collected on the Atlantic coast. The high molecular diversity found in populations in the Amazon Basin was related to the great number of sandfly vector(s) in that region. The results of the restriction fragment length polymorphism analysis of the ITS depicted considerable intraspecific variation. Genotypic groups A, B, and C contained 39, 40, and 22 isolates, which were divided into 16, 10, and 15 genotypes, respectively. The genetic polymorphism observed demonstrates the degree of diversity of L. (V.) braziliensis strains from different regions where they are endemic. The results reinforce the clonal theory for Leishmania parasites showing the genetic diversity of this pathogen and an association of L. (V.) braziliensis genotypes with specific transmission cycles, probably reflecting an adaptation of different clones to the vector species involved.