Role of Leishmania donovani and its lipophosphoglycan in CD4+ T-cell activation-induced human immunodeficiency virus replication

The cytokine/chemokine response in Leishmania/HIV infection and co-infection

HIV infection progressively weakens the immune system by infecting and destroying cells involved in host defense. Viral infection symptoms are generated and aggravated as immunosuppression progresses, triggered by the presence of opportunistic infections: among these is leishmaniasis, a disease caused by the intracellular parasite Leishmania. The incidence of this co-infection is growing progressively due to the geographic distribution overlap. Both pathogens infect monocytes/macrophages and dendritic cells, although they can also modulate the activity of other cells without co-infecting, such as T and B lymphocytes. Leishmania/HIV co-infection could be described as a system comprising modulations of cell surface molecule expression, production of soluble factors, and intracellular death activities, leading ultimately to the potentiation of infectivity, replication, and spread of both pathogens. This review describes the cytokine/chemokine response in Leishmania/HIV infection and co-infection, discussing how these molecules modulate the course of the disease and analyzing the therapeutic potential of targeting this network.

Splenectomy in Patients with Visceral Leishmaniasis Resistant to Conventional Therapy and Secondary Prophylaxis: A Retrospective Cohort

Some patients with visceral leishmaniasis (VL), or kala-azar, suffer relapses and low quality of life despite adequate drug therapy, especially those co-infected with HIV. Occasionally, physicians indicate splenectomy, but the benefit of the procedure needs to be analyzed systematically. Therefore, a retrospective open cohort study was conducted in Teresina, Brazil. Inpatients from a reference hospital with relapsing VL who had a rescue splenectomy between 2012 and 2019 after the nationally recommended drug therapy failed were studied. The procedure's risks and benefits were assessed in a limited-resource setting. The primary outcomes were surgical complications, complete blood count, CD4+ cell count, hospitalizations, survival time, and medical complications preceding death. Thirteen adult patients received medical and surgical indications of splenectomy (12 men and one woman). Eleven had HIV infection. Two had early and two had late complications. Four died, all of whom were infected with HIV. An additional HIV-coinfected patient, apart from the cohort, died just before surgery. The death rate after surgery was 13.3 overall and 22.1 per 100 person-years among HIV-infected patients (31% overall and 36%, respectively). The impressive rise of complete blood counts and reduction of blood transfusions and hospitalizations were observed among all patients. Also, a meaningful increase in CD4+ cells in HIV-infected patients was noted. Splenectomy may benefit patients with relapsing VL. However, before performing splenectomy, available combined drug therapy for VL should be tried.

Effect of Health Care on Quality of Life among Human Immunodeficiency Virus Infected Adults With and Without Visceral Leishmaniasis in northwest Ethiopia: A Longitudinal Follow-Up Study

There has been a scarcity of data on the effect of health care on the quality of life (QoL) of human immunodeficiency virus (HIV)- and visceral leishmaniasis (VL)- coinfected patients over time. We sought to assess the change that health care brings about in the QoL of HIV patients with and without VL and its predictors in 6 months. A total of 465 HIV patients without VL and 125 HIV-VL-coinfected patients were enrolled in the longitudinal follow-up study from October 2015 to September 2016. Data on QoL at baseline and in 6 months were collected by trained nurses through face-to-face interviews using a short Amharic version of World Health Organization QoL instrument for HIV clients. Multiple linear regressions were used to assess the predictors of health-related QoL. There was an improvement in all of the domains of QoL at the sixth month follow-up compared with the baseline for both groups of patients (P < 0.001). Lack of social support and income were associated with the low improvement in QoL in most of the domains in both groups. Compared with patients having severe acute malnutrition, patients having moderate acute malnutrition and normal nutritional status were better in most of the QoL domains in both groups of patients. Both antiretroviral and anti-VL treatments showed improvement in all dimensions of QoL. Income, social support, and nutritional status were the predictors for most of the QoL domains.

Health-related quality of life of HIV infected adults with and without Visceral Leishmaniasis in Northwest Ethiopia

BACKGROUND

Health-related quality of life (HRQoL) is an important outcome measure among HIV infected patients receiving antiretroviral therapy (ART). When HIV infected patients coinfected with Visceral Leishmaniasis (VL) the problem become severe because VL accelerates HIV replication and disease progression. The impact of VL on the quality of life of HIV infected patients has not been studied. In this study in Ethiopia, we compared the quality of life of HIV infected patients with and without VL.

METHODS

A cross-sectional study was conducted from October 2015 to September 2016 in selected health centers and hospitals, in Northwest Ethiopia. Data on quality of life was collected by trained nurses. The instrument used to collect the data was the short Amharic version of the World Health Organization Quality of Life for HIV clients (WHOQoL-HIV). Depression was assessed using the validated version of Kessler scale. Data was entered and analyzed using SPSS version 20. Descriptive statistics, bivariate and multivariate linear regression model was used to summarize the results.

RESULTS

A total of 590 study participants were included in the study with response rate of 95%. Of the 590 patients included in our study 125 (21%) were HIV-VL coinfection. HIV-VL coinfected patients had a lower quality of life in all the domains as compared to HIV patients without VL. Depression was consistently and strongly associated with all the quality of life domains of both groups. Also, in HIV infected patients a longer duration in ART was associated with higher HRQoL domains except for the spiritual and level of independence domains. With regard to HIV-VL coinfected patients, a longer duration in ART was associated with psychological, spiritual and level of independence domains of HRQoL. Demographics, clinical, and treatment characteristics resulted few significant associations with HRQoL domains of both groups.

CONCLUSION

HIV-VL coinfected patients had a poor quality of life in all the domains of the WHOQoL-HIV instrument. Depression, duration of ART and education were strongly associated with the quality of life. Depression should be targeted for intervention to improve the quality of life.

Prevalence of Human Immunodeficiency Virus and associated factors among Visceral Leishmaniasis infected patients in Northwest Ethiopia: a facility based cross-sectional study

Background

Visceral Leishmaniasis coinfection with HIV/AIDS has emerged as a series of disease pattern. It most often results in unfavorable responses to treatment, frequent relapses, and deaths. Scarce data is available regarding the prevalence of HIV and associated factors among Visceral Leishmaniasis coinfected patients. This study sought to determine the prevalence of HIV and associated factors among Visceral Leishmaniasis infected patients.

Methods

Facility based cross-sectional study was conducted from October, 2015 to August, 2016 in Northwest Ethiopia. Cluster sampling technique was used to select 462 Visceral Leishmaniasis infected patients. Serologic and parasitological test results have been used to diagnose Visceral Leishmaniasis. The HIV diagnosis was based on the national algorithm with two serial positive rapid test results. In case of discrepancy between the two tests, Uni-Gold ^TM was used as a tie breaker. Structured questionnaire was used to collect independent variables. Data was entered by using Excel and analyzed by using SPSS version 20. Descriptive statistics and logistic regression model was used to analyze the data.

Results

A total of 462 study participants were included in the study with a response rate of 92.4%. HIV and Visceral Leishmaniasis coinfection was found to be 17.75% with 95% CI; 14.30–21.40. Age ≥ 30 years (AOR = 22.58, 95% CI 11.34, 45.01), urban residents (AOR = 2.02, 95% CI 1.16, 4.17) and daily laborer workers (AOR = 4.99, 95% CI 2.33, 10.68) were significantly associated with HIV and Visceral Leishmaniasis coinfection.

Conclusion

HIV and Visceral Leishmaniasis coinfection in the Northwest Ethiopia was found to be low. Age, residence and employment were independently associated with HIV-VL coinfection in the Northwest Ethiopia. It is better to design interventions to prevent and control HIV-VL coinfection for productive age groups (age ≥ 30) and daily laborers.

Interplay between a cytosolic and a cell surface carbonic anhydrase in pH homeostasis and acid tolerance of Leishmania

Leishmania parasites have evolved to endure the acidic phagolysosomal environment within host macrophages. How Leishmania cells maintain near-neutral intracellular pH and proliferate in such a proton-rich mileu remains poorly understood. We report here that, in order to thrive in acidic conditions, Leishmania major relies on a cytosolic and a cell surface carbonic anhydrase, LmCA1 and LmCA2, respectively. Upon exposure to acidic medium, the intracellular pH of the LmCA1^+/-, LmCA2^+/- and LmCA1^+/-:LmCA2^+/- mutant strains dropped by varying extents that led to cell cycle delay, growth retardation and morphological abnormalities. Intracellular acidosis and growth defects of the mutant strains could be reverted by genetic complementation or supplementation with bicarbonate. When J774A.1 macrophages were infected with the mutant strains, they exhibited much lower intracellular parasite burdens than their wild-type counterparts. However, these differences in intracellular parasite burden between the wild-type and mutant strains were abrogated if, before infection, the macrophages were treated with chloroquine to alkalize their phagolysosomes. Taken together, our results demonstrate that haploinsufficiency of LmCA1 and/or LmCA2 renders the parasite acid-susceptible, thereby unravelling a carbonic anhydrase-mediated pH homeostatic circuit in Leishmania cells.

Magnitude of visceral leishmaniasis and poor treatment outcome among HIV patients: meta-analysis and systematic review

Background

Visceral leishmaniasis (VL) coinfection with HIV/AIDS most often results in unfavorable responses to treatment, frequent relapses, and premature deaths. Scarce data are available, regarding the magnitude and poor treatment outcomes of VL-HIV coinfection.

Objective

The main objective of this systematic review was to describe the pooled prevalence of VL and poor treatment outcome among HIV patients.

Review methods

Electronic databases mainly PubMed were searched. Databases, such as Google and Google scholar, were searched for gray literature. Articles were selected based on their inclusion criterion, whether they included HIV-positive individuals with VL diagnosis. STATA 11 software was used to conduct a meta-analysis of pooled prevalence of VL-HIV coinfection.

Results

Fifteen of the 150 articles fulfilled the inclusion criteria. A majority of the study participants were males between 25 years and 41 years of age. The pooled prevalence of VL-HIV coinfection is 5.2% with 95% confidence interval of (2.45–10.99). Two studies demonstrated the impact of antiretroviral treatment on reduction in relapse rate compared with patients who did not start antiretroviral treatment. One study showed that the higher the baseline CD4+ cell count (>100 cells/mL) the lower the relapse rate. Former VL episodes were identified as risk factors for relapse in two articles. In one of the articles, an earlier bout of VL remains significant in the model adjusted to other variables.

Conclusion

The pooled prevalence of VL in HIV-infected patients is low and an earlier bout of VL and CD4+ count <100 cells/mL at the time of primary VL diagnosis are factors that predict poor treatment outcome.

Immunostimulatory potential and proteome profiling of Leishmania donovani soluble exogenous antigens

Isolation of the soluble exogenous antigens (SEAgs), its immune response study and proteome profiling is an essential prerequisite for understanding the molecular pathogenesis of Leishmania donovani. The immunostimulatory potential of L. donovani SEAgs, purified from culture of L. donovani clinical isolate, was evaluated for their ability to induce cellular responses in treated/cured hamsters. SEAgs induced significant proliferative responses in lymphocytes (SI 5.6 ± 2.3; P < 0.01) isolated from cured hamster. In addition, significant NO production in response to SEAgs was also noticed in macrophages of hamsters, mouse and human cell lines (J774A-1 and THP1). Western blot analyses with antibodies against proteophosphoglycan (PPG; surface-expressed and secreted molecule) of L. donovani revealed that PPG molecules are also present in L. donovani SEAgs. Mass spectrometry (MS)-based proteome analysis of 12 protein bands of SEAgs through MALDI-TOF/TOF endorsed the identification of some Th1-stimulatory immunogenic proteins. These immunogenic proteins may offer increased hope for the discovery of new promising vaccine candidates against visceral leishmaniasis (VL). The overall results suggest that immunostimulatory molecules are present in the SEAgs, which may be further exploited, for developing a subunit vaccine against VL a fatal human disease.

Changing trends in the epidemiology, clinical presentation, and diagnosis of Leishmania-HIV co-infection in India

Following the HIV epidemic, several countries have reported co-infections of Leishmania with HIV. Co-infection with these two pathogens results in rapid disease progression, more severe disease, and a poor response to treatment. A systematic review of the literature from India is presented herein. Since the first case of visceral leishmaniasis (VL) and HIV was published from India in 1999, a number of cases of HIV-Leishmania co-infection have been reported, but the proportion has been low (0.029-0.4%), as also reported in other countries where these two diseases are co-endemic. More than 89 cases of VL-HIV and 10 cases of cutaneous leishmaniasis (CL)-HIV have been published since 1999. Of these latter 10 cases, five had simple CL and five cases manifested with diffuse cutaneous leishmaniasis (DCL). In addition, one case of post-kala-azar mucocutaneous leishmaniasis in a patient with full-blown AIDS has also been reported. In two cases, it could not be ascertained whether they were cases of DCL or post-kala-azar dermal leishmaniasis from the description. Although the first case of VL-HIV co-infection was reported from the sub-Himalayan state of Uttarakhand, most cases have been reported from the VL endemic state of Bihar. HIV-Leishmania is not alarmingly high in India. Most cases were found to have occurred during 1997-2007. After that, the number of new cases decreased. This is most probably due to the low prevalence of HIV in VL and CL endemic regions and to the free supply of highly active antiretroviral therapy for HIV-infected patients.

Alteration of sFAS and sFAS ligand expression during canine visceral leishmaniosis

Visceral leishmaniosis (VL) is caused by intracellular parasites of the genus Leishmania that affect humans and several animal species. Dogs are one of the main urban reservoirs of Leishmania infantum and play a central role in the transmission cycle to humans via sandflies. CD3+ cells apoptosis is involved in the immune response in VL. Dysregulation of apoptosis has been implicated in various disease states. An important regulator of apoptosis is the FAS-FAS-associated death domain protein (cluster of differentiation 95 - CD95) and FASL-FAS ligand protein (cluster of differentiation 178 - CD178) system involved in the down-regulation of immune reactions and in T cell-mediated cytotoxicity. FAS is a member of the tumor necrosis factor (TNF) receptor super family, which can be expressed in transmembrane or soluble forms. The soluble levels of FAS (sFAS), FASL (sFASL) and active Caspase-3, this last related to apoptotic cascade, were investigated in the spleen of 19 symptomatic dogs presenting moderate VL and 6 healthy dogs, determined by ELISA assay. The splenic parasite load was determined by real-time PCR monitoring of amplification of the intergenic internal transcribed spacer (ITS1) gene of parasite rRNA. sFAS levels were lower (p<0.05). sFASL and active Caspase-3 levels were higher (p<0.05) in dogs with VL compared with controls. Negative correlation was observed between parasite burden and sFASL levels. The increase in sFASL could be related to the mechanism involved in the elimination of the parasite.

The immunology of Leishmania/HIV co-infection

Leishmaniases are emerging as an important disease in human immunodeficiency virus (HIV)-infected persons living in several sub-tropical and tropical regions around the world, including the Mediterranean. The HIV/AIDS pandemic is spreading at an alarming rate in Africa and the Indian subcontinent, areas with very high prevalence of leishmaniases. The spread of HIV into rural areas and the concomitant spread of leishmaniases to suburban/urban areas have helped maintain the occurrence of Leishmania/HIV co-infection in many parts of the world. The number of cases of Leishmania/HIV co-infection is expected to rise owing to the overlapping geographical distribution of the two infections. In Southwestern Europe, there is also an increasing incidence of Leishmania/HIV co-infection (particularly visceral leishmaniasis) in such countries as France, Italy, Spain and Portugal. Studies suggest that in humans, very complex mechanisms involving dysregulation of host immune responses contribute to Leishmania-mediated immune activation and pathogenesis of HIV. In addition, both HIV-1 and Leishmania infect and multiply within cells of myeloid or lymphoid origin, thereby presenting a perfect recipe for reciprocal modulation of Leishmania and HIV-1-related disease pathogenesis. Importantly, because recovery from leishmaniases is associated with long-term persistence of parasites at the primary infection sites and their draining lymph nodes, there is very real possibility that HIV-mediated immunosuppression (due to CD4(+) T cell depletion) could lead to reactivation of latent infections (reactivation leishmaniasis) in immunocompromised patients. Here, we present an overview of the immunopathogenesis of Leishmania/HIV co-infection and the implications of this interaction on Leishmania and HIV disease outcome.

Decreased memory T-cell response and function in human immunodeficiency virus-infected patients with tegumentary leishmaniasis

The effects of human immunodeficiency virus (HIV) on the immune response in patients with cutaneous leishmaniasis have not yet been fully delineated. This study quantified and evaluated the function of memory T-cell subsets in response to soluble Leishmania antigens (SLA) from patients coinfected with HIV and Leishmania with tegumentary leishmaniasis (TL). Eight TL/HIV coinfected subjects and 10 HIV seronegative subjects with TL were evaluated. The proliferative response of CD4+and CD8+T-cells and naïve, central memory (CM) and effector memory (EM) CD4+T-cells in response to SLA were quantified using flow cytometry. The median cell division indices for CD4+and CD8+T-cells of coinfected patients in response to SLA were significantly lower than those in patients with Leishmania monoinfection (p < 0.05). The proportions of CM and EM CD4+T-cells in response to SLA were similar between the coinfected patients and patients with Leishmania monoinfection. However, the median CM and EM CD4+T-cell counts from coinfected patients were significantly lower (p < 0.05). The reduction in the lymphoproliferative response to Leishmania antigens coincides with the decrease in the absolute numbers of both EM and CM CD4+T-cells in response to Leishmania antigens in patients coinfected with HIV/Leishmania.

CD95 (FAS) and CD178 (FASL) induce the apoptosis of CD4+ and CD8+ cells isolated from the peripheral blood and spleen of dogs naturally infected with Leishmania spp

Infected dogs are urban reservoirs of Leishmania chagasi, which is a causative agent of visceral leishmaniasis (VL). Dogs exhibit immune suppression during the course of this disease, and lymphocyte apoptosis is involved in this process. To investigate apoptosis and the expression levels of FAS-FAS-associated death domain protein (CD95 or APO-1), FASL-FAS ligand protein (CD178), and TRAIL-TNF-related apoptosis-inducing ligand (CD253) receptors in peripheral blood mononuclear cells and spleen leukocytes from 38 symptomatic dogs with moderate VL and 25 healthy dogs were evaluated by flow cytometry. The apoptosis rate of blood and splenic CD4+ and CD8+ cells was higher in infected dogs than in healthy dogs. The expression levels of FAS and FASL in blood and splenic CD4+ cells were lower in infected dogs than in healthy dogs. FAS expression in CD8+ cells was higher in infected dogs than in healthy dogs; in contrast, FASL expression was lower in infected dogs. The expression of the TRAIL receptor increased only in splenic CD8+ cells from infected dogs. The FAS and FAS-L blocking antibodies confirmed the importance of these receptors in apoptosis. Our results enhance the current understanding of the immune response in dogs infected with L. chagasi, facilitating the future development of therapeutic interventions to reduce lymphocyte depletion.

Apoptosis in T lymphocytes from spleen tissue and peripheral blood of L. (L.) chagasi naturally infected dogs

Dogs are the main domestic reservoirs of L. (L.) chagasi. Once in the vertebrate host, the parasite may cause visceral leishmaniasis, which can also be transmitted to humans. Infected symptomatic dogs show disorganization in the white pulp in spleen tissue and a reduction in T lymphocytes in peripheral blood. To investigate whether apoptosis is involved in white pulp disorganization and diminished T cell counts in peripheral blood, apoptotic T cells from the spleen and peripheral blood of dogs naturally infected with L. (L.) chagasi and presenting clinical manifestations were quantified and compared with healthy dogs. Thirteen symptomatic adult dogs infected by L. (L.) chagasi and six healthy dogs from a nonendemic area (controls) were included in the study. Samples from spleen and peripheral blood were used to quantify apoptosis in CD3 lymphocytes by flow cytometry using Anexin V and Multicaspase kits; the results were compared using the Mann Whitney test. The percentage of total T cells was lower in Leishmania infected dogs compared to healthy controls (P<0.05). Apoptosis levels in T cells from PBMC and spleen were higher in infected dogs than in controls (P<0.05). The least squares method test was used to determine the effect between the degree of structural organization of spleen white pulp and the percentage of apoptosis in the spleen. A significant effect on the level of white pulp morphological disorganization and percentage of apoptosis in spleen T cells was observed (F=20.45; P=0.0014). These data suggest that apoptosis is an important for the immunopathogenesis of canine visceral leishmaniasis.

HIV/AIDS-associated visceral leishmaniasis in patients from an endemic area in Central-west Brazil

An increase in morbidity associated with visceral leishmaniasis (VL) in human immunodeficiency virus (HIV)/AIDS patients has been described in Africa and the Mediterranean. Despite the high endemicity of VL and HIV-1/AIDS in Brazil, this association has not been thoroughly investigated. Our aim was to evaluate the epidemiologic and clinical characteristics of VL-HIV-1/AIDS cases from Central-west [Mato Grosso do Sul (MS)] Brazil. Medical records of 23 VL-HIV-1/AIDS patients were reviewed. Patients were predominantly adult males (87%) and 34.8% of the patients were intravenous drug users (IVDU). Leishmaniasis was the first opportunistic infection in 60% of the HIV-1 patients. Fever occurred in all patients, although splenomegaly and hepatomegaly were absent in 21.7% of the cases. CD4+ T-cell counts were below 200 cells/mm(3) in 80% of the cases and the counts did not increase after clinical remission despite antiretroviral therapy. The first drug chosen to treat the cases was antimonial, but the therapeutic regimen was altered to amphotericin B in 12 of 17 cases due to side effects. Relapses were reported in 56.5% of the patients. IVDU may constitute an important risk factor for the transmission of both diseases in MS. VL-HIV-1/AIDS patients in MS share similar clinical characteristics as those from other endemic regions worldwide. Thus, these findings are critical for improving the surveillance of VL-HIV/AIDS patients.

Tracing immunity to human leishmaniasis

People who have recovered from leishmaniasis are believed to have long-lasting protection against subsequent infection. Understanding the immunological changes that are associated with protection from cure of and susceptibility to the disease are fundamental to both designing and evaluating vaccine candidates against the leishmaniases. In the quest for a vaccine against leishmaniasis, appropriate surrogate markers of immunity would be valuable and cost effective. Biomarkers would ease screening and selection of potentially efficient vaccine candidates. Moreover, biomarkers of disease may be used to monitor disease and aid therapeutic prognosis. This would be useful in the evaluation of both existing and new drugs, making invasive post-treatment evaluation redundant. Biomarkers may also be indicative of the severity of the disease and may be able to predict the outcome of an infection and indicate whether the patient will spontaneously recover, exhibit mild symptoms or if the disease is disseminating and will be severe. In this article we discuss the immunological changes associated with different forms of human leishmaniasis and the value of appropriate immunological biomarkers in finding an effective vaccine and an evaluation of therapies against leishmanial disease will be given.

Anni 2.0: a multipurpose text-mining tool for the life sciences

Anni 2.0 provides an ontology-based interface to MEDLINE.

Anni 2.0 is an online tool () to aid the biomedical researcher with a broad range of information needs. Anni provides an ontology-based interface to MEDLINE and retrieves documents and associations for several classes of biomedical concepts, including genes, drugs and diseases, with established text-mining technology. In this article we illustrate Anni's usability by applying the tool to two use cases: interpretation of a set of differentially expressed genes, and literature-based knowledge discovery.

The relationship between leishmaniasis and AIDS: the second 10 years

To date, most Leishmania and human immunodeficiency virus (HIV) coinfection cases reported to WHO come from Southern Europe. Up to the year 2001, nearly 2,000 cases of coinfection were identified, of which 90% were from Spain, Italy, France, and Portugal. However, these figures are misleading because they do not account for the large proportion of cases in many African and Asian countries that are missed due to a lack of diagnostic facilities and poor reporting systems. Most cases of coinfection in the Americas are reported in Brazil, where the incidence of leishmaniasis has spread in recent years due to overlap with major areas of HIV transmission. In some areas of Africa, the number of coinfection cases has increased dramatically due to social phenomena such as mass migration and wars. In northwest Ethiopia, up to 30% of all visceral leishmaniasis patients are also infected with HIV. In Asia, coinfections are increasingly being reported in India, which also has the highest global burden of leishmaniasis and a high rate of resistance to antimonial drugs. Based on the previous experience of 20 years of coinfection in Europe, this review focuses on the management of Leishmania-HIV-coinfected patients in low-income countries where leishmaniasis is endemic.

Kutane Leishmaniasis

Infections with Leishmania are increasing worldwide because of tourism and job-related travel; central Europe is no exception. Infections often first become apparent after return from an endemic region. Depending on the Leishmania species and the host immune status, different forms of cutaneous (CL), mucocutaneous (MCL) (L. brasiliensis complex) or visceral leishmaniasis (L. donovani as well as L. infantum) may develop. CL may heal spontaneously with scarring but can evolve into diffuse CL (with reduced immune response to L. amazonensis, L. guyanensis, L. mexicana or L. aethiopica) or into recurrent CL. Diagnostic criteria include travel to an endemic area as well as ulcerated plaques or nodules on an exposed site which show no tendency towards healing over 3-4 weeks. Differential diagnostic considerations include ecthyma, other infectious ulcers, and malignant neoplasms. The diagnosis is confirmed by finding Leishmania in a smear or tissue biopsy, as well as by culture. Therapy options range from topical treatment of simple CL of the Old World caused by L. major to systemic therapy which is needed for most complex cases of CL as well as MCL. Miltefosine is a less toxic option to replace the antimony compounds.

CD4+ CCR5+ and CD4+ CCR3+ lymphocyte subset and monocyte apoptosis in patients with acute visceral leishmaniasis

The potential involvement of apoptosis in the pathogenesis of visceral leishmaniasis (VL) was examined by studying spontaneous and Leishmania antigen (LAg)-induced apoptosis using cryopreserved peripheral blood mononuclear cells (PBMC) of Sicilian patients with VL. Results indicate that monocytes and T lymphocytes from acute VL patients show a significantly higher level of apoptosis compared with that observed in healed subjects. The percentage of apoptotic cells was higher in monocytes than in T lymphocytes. T cells involved in programmed cell death (PCD) were mainly of the CD4(+) phenotype. In particular, the T helper 1-type (Th1) subset, as evaluated by chemokine receptor-5 (CCR5) expression, is involved in this process. Cell death in Th1-type uses a CD95-mediated mechanism. Furthermore, Th1-type CCR5(+) cells are prone to cell suicide in an autocrine or paracrine way, as attested by enhanced expression of CD95L in acute VL patients. The reduction in Th1-type cells by apoptosis was confirmed by the decrease in interferon-gamma secretion. In conclusion, apoptosis of monocytes, CD4(+) and CD4(+) CCR5(+) T cells could be involved in the failure of cell mediated immunity that is responsible for severe immune-depression in VL.

Immunization with Leishmania major exogenous antigens protects susceptible BALB/c mice against challenge infection with L. major

The potential of Leishmania major culture-derived soluble exogenous antigens (SEAgs) to induce a protective response in susceptible BALB/c mice challenged with L. major promastigotes was investigated. Groups of BALB/c mice were immunized with L. major SEAgs alone, L. major SEAgs coadministered with either alum (aluminum hydroxide gel) or recombinant murine interleukin-12 (rmIL-12), L. major SEAgs coadministered with both alum and rmIL-12, and L. major SEAgs coadministered with Montanide ISA 720. Importantly and surprisingly, the greatest and most consistent protection against challenge with L. major was seen in mice immunized with L. major SEAgs alone, in the absence of any adjuvant. Mice immunized with L. major SEAgs had significantly smaller lesions that at times contained more than 100-fold fewer parasites. When lymphoid cells from L. major SEAg-immunized mice were stimulated with leishmanial antigen in vitro, they proliferated and secreted a mixed profile of type 1 and type 2 cytokines. Finally, analyses with Western blot analyses and antibodies against three surface-expressed and secreted molecules of L. major (lipophosphoglycan, gp46/M2/PSA-2, and gp63) revealed that two of these molecules are present in L. major SEAgs, lipophosphoglycan and the molecules that associate with it and gp46/M2/PSA-2.

Leishmania infantum promotes replication of HIV type 1 in human lymphoid tissue cultured ex vivo by inducing secretion of the proinflammatory cytokines TNF-alpha and IL-1 alpha

Parasitic infections such as leishmaniasis can modulate the life cycle of HIV-1 and disease progression. Coinfection with HIV-1 and Leishmania has emerged as a serious threat in countries where both pathogenic agents are widespread. Although there are numerous clinical reports illustrating the cofactor role played by Leishmania in HIV-1-infected patients, there is still no information on the contribution of Leishmania to the biology of HIV-1 in human lymphoid tissue that is considered a major in vivo site of virus production. In this study we explored the modulatory effect of Leishmania on the process of HIV-1 infection using ex vivo cultured human tonsillar tissue. We found that the protozoan parasite Leishmania enhances both HIV-1 transcription and virus production after infection of human tonsillar tissue infected ex vivo with viral strains bearing various coreceptor usage profiles. Studies conducted with pentoxifylline and neutralizing Abs revealed that the Leishmania-mediated increase in HIV-1 production was linked to a higher production of TNF-alpha and IL-1alpha. Our findings help to unravel the molecular mechanism(s) through which the two microorganisms interact and provide information that may be useful for the design of more effective therapeutic strategies aimed at controlling disease progression in persons dually infected with HIV-1 and Leishmania. This work also indicates that histocultures of human lymphoid tissue infected by both pathogens represent an ideal experimental cell system to dissect interactions occurring between HIV-1 and an opportunist pathogen in a human microenvironment that approximates conditions prevailing under physiological situations.

Thalidomide for erythema nodosum leprosum and other applications

Thalidomide, administered as a sedative and antiemetic decades ago, was considered responsible for numerous devastating cases of birth defects and consequently was banned from markets worldwide. However, the drug remarkably has resurfaced with promise of immunomodulatory benefit in a wide array of immunologic disorders for which available treatments were limited. It is approved by the Food and Drug Administration for erythema nodosum leprosum (ENL). Although the relative paucity of leprosy and ENL worldwide may perceivably limit interest in and knowledge about thalidomide, increasing numbers of new and potential uses expand its applicability widely beyond ENL. Thalidomide, an inhibitor of tumor necrosis factor a, is the best known agent for short-term treatment of ENL skin manifestations, as well as postremission maintenance therapy to prevent recurrence. For this indication, it is effective as monotherapy and as part of combination therapy with corticosteroids. Studies of thalidomide in chronic graft-versus-host disease showed benefit in children and adults as treatment, but not as prophylaxis. The agent has been administered successfully for treatment of cachexia related to cancer, tuberculosis, and human immunodeficiency virus infection, although evidence of efficacy is inconclusive. Thalidomide monotherapy effectively induced objective response in trials in patients with both newly diagnosed and advanced or refractory multiple myeloma. Combination therapy with thalidomide and corticosteroids was also effective in these patients, as well as in treatment of aphthous and genital ulcers. Limited evidence supports the drug's benefit in treatment of Kaposi's sarcoma. Other thalidomide applications include Crohn's disease, rheumatoid arthritis, and multiple sclerosis. Somnolence, constipation, and rash were the most frequently cited adverse effects in studies, but thalidomide-induced neuropathy and idiopathic thromboembolism were critical causes for drug discontinuation. Thalidomide is still contraindicated in pregnant women, women of childbearing age, and sexually active men not using contraception. Clinicians should be conversant with thalidomide in ENL (its primary application) in the natural course of leprosy, as well as in the agent's other applications.

Alteration of Fas and Fas ligand expression during human visceral leishmaniasis

Several studies in murine systems have suggested a role of apoptosis in the pathogenesis of leishmaniasis. However, the role of apoptosis in visceral leishmaniasis in man has not been explored. In this study, we show that patients with visceral leishmaniasis demonstrate significant dysregulation of Fas and Fas ligand. Levels of soluble Fas (sFas) and soluble Fas ligand (sFasL) were elevated in plasma of patients with active visceral leishmaniasis (VL) and individuals co-infected with VL-HIV-1 compared to healthy controls. The levels of sFas and sFasL were normalized 6 months after successful treatment. In VL patients, the expression of membrane bound Fas, and to a lower extent FasL, were up-regulated on Leishmania donovani-infected spleen cells, the site of parasite multiplication. Expression of Fas and FasL on peripheral blood mononuclear cells was within normal range, probably reflecting that the blood is not a normal site of L. donovani infection. Furthermore, this is suggested by the finding that in vitro infection of macrophages with L. donovani up-regulated Fas expression on the surface of infected cells and enhanced the levels of sFasL in supernatants from infected cultures. How this dysregulation may affect the pathogenesis of human visceral leishmaniasis is discussed.

Intracellular protozoan parasites and apoptosis: diverse strategies to modulate parasite-host interactions

Programmed cell death (apoptosis) is an important regulator of the host's response during infection with a variety of intracellular protozoan parasites. Parasitic pathogens have evolved diverse strategies to induce or inhibit host-cell apoptosis, thereby modulating the host's immune response, aiding dissemination within the host or facilitating intracellular survival. Here, we review the molecular and cell-biological mechanisms of the pathogen-induced modulation of host-cell apoptosis and its effects on the parasite-host interaction and the pathogenesis of parasitic diseases. We also discuss the previously unrecognized phenomenon of apoptotic cell death in (unicellular) protozoan parasites and its potential implications.

Visceral leishmaniasis in human immunodeficiency virus (HIV)-infected and non-HIV-infected patients. A comparative study

Visceral leishmaniasis is an endemic infection in Mediterranean countries, where it has become a frequent complication of acquired immunodeficiency syndrome (AIDS). The incidence of visceral leishmaniasis is increasing in Spain due to human immunodeficiency virus (HIV)-related cases, but some aspects of its epidemiology, clinical features, and management remain unknown. In addition, no comparative clinical studies about the disease in HIV-infected and non-HIV-infected patients have been reported. During a 24-year period, 120 cases of visceral leishmaniasis were diagnosed at our institution and 80 (66%) were associated with HIV infection. The mean age at diagnosis was higher in HIV-infected that in non-HIV-infected patients (33.2 versus 23.2 yr; p = 0.002), but the male/female ratio was similar in both groups. The main risk factor for HIV infection was intravenous drug abuse (78.7%). The clinical presentation of leishmaniasis was similar in both groups, but HIV-infected patients had a lower frequency of splenomegaly than HIV-negative individuals (80.8% versus 97.4%; p = 0.02). HIV-infected patients had a greater frequency and degree of leukopenia, lymphocytopenia, and thrombocytopenia. Most of them were profoundly immunosuppressed (mean CD4+ lymphocyte count, 90 cells/mm3) at the time of diagnosis of leishmaniasis, and 53.7% had AIDS. The sensitivity of serologic studies for Leishmania was significantly lower in HIV-infected than in non-HIV-infected patients (50% versus 80%; p < 0.001), but the diagnostic yield of bone marrow aspirate (67.1% versus 79.4%) and bone marrow culture (62.9% versus 66.6%) was similar in both groups. After initial treatment, the response rate was significantly lower in HIV-infected than in non-HIV-infected individuals (54.8% versus 89.7%; p = 0.001). The relapse rate was 46.2% and 7.5%, respectively (p < 0.001). Secondary prophylaxis with antimonial compounds or amphotericin B seems to be useful in preventing relapses in HIV-infected patients. The mortality rate was higher (53.7% versus 7.5%; p < 0.001) and the median survival time shorter (25 versus > 160 mo; p < 0.001) in AIDS patients than in HIV-negative individuals. Although leishmaniasis could contribute to death in a significant number of HIV-infected patients, it was the main cause of death in only a few of them. The CD4+ lymphocyte count and the use of highly active antiretroviral therapy and secondary prophylaxis for leishmaniasis were the most significant prognostic factors for survival in AIDS patients. Visceral leishmaniasis behaves as an opportunistic infection in HIV-infected individuals and should be considered as an AIDS-defining disease.

A novel role for tumor necrosis factor-alpha in regulating susceptibility of activated CD4+ T cells from human and nonhuman primates for distinct coreceptor using lentiviruses

Although CD4+ T-cell activation has long been shown to promote infection and replication of simian immunodeficiency virus (SIV) and HIV, recent studies have documented that not all activated CD4+ T cells from human and nonhuman primates are susceptible to infection with HIV/SIV, respectively. Activation of CD4+ T cells with anti-CD3 + anti-CD28 conjugated beads led to induction of a state of anti-viral resistance to infection with strains of viruses that primarily use CCR5 as a coreceptor. The studies reported herein were designed to address the mechanism by which anti-CD3 + anti-CD28-induced stimulation in turn induced antiviral resistance. Results of these studies show that the anti-viral resistance induced by activation of CD4+ T cells with anti-CD3 + anti-CD28 is primarily conferred by the synthesis of tumor necrosis factor-alpha (TNF-alpha), and highlight a unique regulatory role for TNF-alpha in regulating synthesis of MIP-1alpha, MIP-1beta, and regulated-on-activation normal T-expressed and secreted cells, which contributes to this state of antiviral resistance to R5-tropic strains of HIV/SIV. However, while TNF-alpha has a protective role in antiviral resistance of activated CD4+ T cells to R5-tropic viruses, it enhances CXCR4 expression of CD4+ T cells and mediates increased susceptibility to infection with X4-tropic strains of HIV and recombinant SIVs. The results of the studies reported herein also suggest that it is not the Th1 v/s Th2 cytokine profile but the mode of CD4+ T-cell activation that dictates the synthesis of distinct cytokines which regulate the expression of chemokines and chemokine receptors which in turn regulate and confer susceptibility/resistance to R5 v/s X4-tropic HIV and SIV.