Hiro Goto

Current diagnosis and treatment of cutaneous and mucocutaneous leishmaniasis

Tegumentary leishmaniasis, comprising the cutaneous and mucocutaneous forms, is caused by at least 13 dermotropic species of protozoa of the genus Leishmania, most of which are prevalent in the New World. Although diseases in the Old and New Worlds share similar characteristics, the ultimate manifestations and severity are quite different, with more severe forms associated with mucosal lesions observed in the New World. For the diagnosis and treatment of leishmaniasis, differences based on clinical features, usefulness/sensitivity of diagnostic methods and therapeutic responses are mainly emphasized. We present a critical review of the diagnostic methods, their contribution and the necessity for their improvement/development, particularly in molecular diagnosis aimed at detection and species identification, as well as serodiagnosis. In addition to a review of the drugs currently utilized, we describe differences in their effectiveness in Old and New World leishmaniasis. HIV/Leishmania coinfection is also presented in the context of diagnosis and treatment.

Cutaneous and Mucocutaneous Leishmaniasis

Tegumentary leishmaniases are caused by approximately 15 species of protozoa of the genus Leishmania. They prevail in tropical and subtropical areas of the Old and New World but human mobility also makes them a medical problem in nonendemic areas. Clinical manifestations may comprise cutaneous and mucocutaneous forms that may be localized, disseminated, or diffuse in distribution and may differ in Old and New World leishmaniases. Diagnosis and treatment vary according to the clinical manifestations, geographic area, and Leishmania species involved. This article highlights the diversity and complexity of tegumentary leishmaniases, which are worsened by human immunodeficiency virus/Leishmania coinfection.

Immunity and immunosuppression in experimental visceral leishmaniasis

Leishmaniasis is a disease caused by protozoa of the genus Leishmania, and visceral leishmaniasis is a form in which the inner organs are affected. Since knowledge about immunity in experimental visceral leishmaniasis is poor, we present here a review on immunity and immunosuppression in experimental visceral leishmaniasis in mouse and hamster models. We show the complexity of the mechanisms involved and differences when compared with the cutaneous form of leishmaniasis. Resistance in visceral leishmaniasis involves both CD4+ and CD8+ T cells, and interleukin (IL)-2, interferon (IFN)-gamma, and IL-12, the latter in a mechanism independent of IFN-gamma and linked to transforming growth factor (TGF)-beta production. Susceptibility involves IL-10 but not IL-4, and B cells. In immune animals, upon re-infection, the elements involved in resistance are different, i.e., CD8+ T cells and IL-2. Since one of the immunopathological consequences of active visceral leishmaniasis in humans is suppression of T-cell responses, many studies have been conducted using experimental models. Immunosuppression is mainly Leishmania antigen specific, and T cells, Th2 cells and adherent antigen-presenting cells have been shown to be involved. Interactions of the co-stimulatory molecule family B7-CTLA-4 leading to increased level of TGF-beta as well as apoptosis of CD4+ T cells and inhibition of macrophage apoptosis by Leishmania infection are other components participating in immunosuppression. A better understanding of this complex immune response and the mechanisms of immunosuppression in experimental visceral leishmaniasis will contribute to the study of human disease and to vaccine development.

A Global Comparative Evaluation of Commercial Immunochromatographic Rapid Diagnostic Tests for Visceral Leishmaniasis

Accuracy of rapid diagnostic tests was high in the Indian subcontinent; however, in Brazilian and East African samples, reduced sensitivity suggests that several cannot be used alone to exclude visceral leishmaniasis. Data on ease of use and performance using whole blood and in human immunodeficiency virus coinfections is needed.

Immunoactivation and immunopathogeny during active visceral leishmaniasis

Visceral leishmaniasis is caused by protozoan parasites of the Leishmania donovani complex. During active disease in humans, high levels of IFN-gamma and TNF-alpha detected in blood serum, and high expression of IFN-gamma mRNA in samples of the lymphoid organs suggest that the immune system is highly activated. However, studies using peripheral blood mononuclear cells have found immunosuppression specific to Leishmania antigens; this poor immune response probably results from Leishmania antigen-engaged lymphocytes being trapped in the lymphoid organs. To allow the parasites to multiply, deactivating cytokines IL-10 and TGF-beta may be acting on macrophages as well as anti-Leishmania antibodies that opsonize amastigotes and induce IL-10 production in macrophages. These high activation and deactivation processes are likely to occur mainly in the spleen and liver and can be confirmed through the examination of organ samples. However, an analysis of sequential data from studies of visceral leishmaniasis in hamsters suggests that factors outside of the immune system are responsible for the early inactivation of inducible nitric oxide synthase, which occurs before the expression of deactivating cytokines. In active visceral leishmaniasis, the immune system actively participates in non-lymphoid organ lesioning. While current views only consider immunocomplex deposition, macrophages, T cells, cytokines, and immunoglobulins by diverse mechanism also play important roles in the pathogenesis.

Tegumentary Leishmaniasis as a Manifestation of Immune Reconstitution Inflammatory Syndrome in 2 Patients with AIDS

Immune reconstitution inflammatory syndromes (IRISs) have been reported in patients with human immunodeficiency virus/acquired immunodeficiency syndrome (AIDS) since the introduction of highly active antiretroviral therapy (HAART). This syndrome is characterized by clinical manifestations of opportunistic infections when signs of immune reconstitution are observed during therapy. We report on leishmaniasis, suggestive of HAART-induced IRIS, in 2 patients with AIDS. After beginning HAART, 1 patient presented with disseminated, tegumentary lesions, whereas the other patients preexisting lesions worsened and became more extensive; however, at the same time, their CD4(+) T cell counts were recovering and their virus loads were decreasing significantly. The lesions healed with anti-Leishmania therapy.

Protein disulfide isomerase (PDI) associates with NADPH oxidase and is required for phagocytosis of Leishmania chagasi promastigotes by macrophages

PDI, a redox chaperone, is involved in host cell uptake of bacteria/viruses, phagosome formation, and vascular NADPH oxidase regulation. PDI involvement in phagocyte infection by parasites has been poorly explored. Here, we investigated the role of PDI in in vitro infection of J774 macrophages by amastigote and promastigote forms of the protozoan Leishmania chagasi and assessed whether PDI associates with the macrophage NADPH oxidase complex. Promastigote but not amastigote phagocytosis was inhibited significantly by macrophage incubation with thiol/PDI inhibitors DTNB, bacitracin, phenylarsine oxide, and neutralizing PDI antibody in a parasite redox‐dependent way. Binding assays indicate that PDI preferentially mediates parasite internalization. Bref‐A, an ER‐Golgi‐disrupting agent, prevented PDI concentration in an enriched macrophage membrane fraction and promoted a significant decrease in infection. Promastigote phagocytosis was increased further by macrophage overexpression of wild‐type PDI and decreased upon transfection with an antisense PDI plasmid or PDI siRNA. At later stages of infection, PDI physically interacted with L. chagasi, as revealed by immunoprecipitation data. Promastigote uptake was inhibited consistently by macrophage preincubation with catalase. Additionally, loss‐ or gain‐of‐function experiments indicated that PMA‐driven NADPH oxidase activation correlated directly with PDI expression levels. Close association between PDI and the p22phox NADPH oxidase subunit was shown by confocal colocalization and coimmunoprecipitation. These results provide evidence that PDI not only associates with phagocyte NADPH oxidase but also that PDI is crucial for efficient macrophage infection by L. chagasi.

Interstitial nephritis in human kala-azar☆

Little is known about renal alterations in kala-azar. The renal histopathology of 21 patients admitted to hospital in São Paulo, Brazil, during the period 1960 through 1981 who either died or had a renal biopsy (two cases) is presented. All the specimens showed oedema and diffuse interstitial inflammatory infiltrate of lymphocytes and plasma cells with more compact foci of cells in some areas. In general, glomeruli did not show any important alterations. These aspects were interpreted as acute interstitial nephritis aetiologically related to later phase kala-azar. This interstitial alteration does not usually seem to determine any clinical manifestations. However, it seems that moderate and severe cortical intersitial damage contribute to the onset of renal insufficiency when severe clinical complications occur. The precise mechanisms of this lesion need further investigation since the aetiological agents have not been seen causing the damage locally.

Unusual manifestations of tegumentary leishmaniasis in AIDS patients from the New World

Background  Comorbidity from tegumentary leishmaniasis and AIDS is poorly characterized.

Transmission potential, skin inflammatory response, and parasitism of symptomatic and asymptomatic dogs with visceral leishmaniasis

BackgroundVisceral leishmaniasis in Brazil is caused by the protozoan Leishmania (Leishmania) chagasi and it is transmitted by sandfly of the genus Lutzomyia. Dogs are an important domestic reservoir, and control of the transmission of visceral leishmaniasis (VL) to humans includes the elimination of infected dogs. However, though dogs are considered to be an important element in the transmission cycle of Leishmania, the identification of infected dogs representing an immediate risk for transmission has not been properly evaluated. Since it is not possible to treat infected dogs, they are sacrificed when a diagnosis of VL is established, a measure that is difficult to accomplish in highly endemic areas. In such areas, parameters that allow for easy identification of reservoirs that represents an immediate risk for transmission is of great importance for the control of VL transmission. In this study we aimed to identify clinical parameters, reinforced by pathological parameters that characterize dogs with potential to transmit the parasite to the vector.ResultsThe major clinical manifestations of visceral leishmaniasis in dogs from an endemic area were onicogriphosis, skin lesions, conjunctivitis, lymphadenopathy, and weight loss. The transmission potential of these dogs was assessed by xenodiagnosis using Lutzomyia longipalpis. Six of nine symptomatic dogs were infective to Lutzomyia longipalpis while none of the five asymptomatic dogs were infective to the sandfly. Leishmania amastigotes were present in the skin of all clinically symptomatic dogs, but absent in asymptomatic dogs. Higher parasite loads were observed in the ear and ungueal region, and lower in abdomen. The inflammatory infiltrate was more intense in the ears and ungueal regions of both symptomatic and asymptomatic dogs. In clinically affected dogs in which few or none Leishmania amastigotes were observed, the inflammatory infiltrate was constituted mainly of lymphocytes and macrophages. When many parasites were present, the infiltrate was also comprised of lymphocytes and macrophages, as well as a larger quantity of polymorphonuclear neutrophils (PMNs).ConclusionDogs that represent an immediate risk for transmission of Leishmania in endemic areas present clinical manifestations that include onicogriphosis, skin lesions, conjunctivitis, lymphadenopathy, and weight loss. Lymphadenopathy in particular was a positive clinical hallmark since it was closely related to the positive xenodiagnosis.