Immunomodulatory Therapy of Visceral Leishmaniasis in Human Immunodeficiency Virus-Coinfected Patients

Consistent efficacy and safety of sublingual immunotherapy tablets across allergens and geographic regions

Background: The clinical development program of the SQ grass, ragweed, tree, and house dust mite (HDM) sublingual immunotherapy (SLIT)-tablets for allergic rhinitis/conjunctivitis (AR/C) included clinical trials conducted in North America, Europe, and Japan. Objective: Data from these trials were analyzed to assess efficacy, immunologic mechanisms, and safety outcomes across allergens and geographic regions. Methods: Thirteen phase III, double-blind, placebo controlled trials in the subjects with AR/C were conducted in North America, Europe (including Russia), and Japan (N = 7763 analyzed). Trials were generally similar with respect to medical practice, target population, eligibility criteria, and efficacy and safety monitoring. Data were analyzed for the approved doses in North America and Europe. Four statistical models were used to enhance comparison of the efficacy end points among the trials. Results: The SLIT-tablets demonstrated consistent efficacy across allergens and regions, regardless of the statistical analysis used. Relative improvement in the primary efficacy end point compared with placebo by using the predefined protocol analysis ranged from 17.9% to 32.8%, 17.5% to 19.3%, 20.6% to 38.3%, and 39.6% with the grass, HDM, ragweed, and tree SLIT-tablets, respectively. The kinetics of specific immunoglobulin E (IgE) and IgG4 responses were similar among the allergens and regions. Local application-site reactions were the most common adverse events for all allergens and in all regions. Most treatment-related adverse events for all allergens and in all regions were mild in severity. The rate of systemic allergic reactions was similar across regions (0%-0.54%). Conclusion: Confirmatory phase III trials for SLIT-tablets in the treatment of AR/C showed consistent efficacy, immunologic, and safety outcomes across allergens and geographic regions.

Persistent T cell unresponsiveness associated with chronic visceral leishmaniasis in HIV-coinfected patients

A large proportion of HIV-coinfected visceral leishmaniasis (VL-HIV) patients exhibit chronic disease with frequent VL recurrence. However, knowledge on immunological determinants underlying the disease course is scarce. We longitudinally profiled the circulatory cellular immunity of an Ethiopian HIV cohort that included VL developers. We show that chronic VL-HIV patients exhibit high and persistent levels of TIGIT and PD-1 on CD8+/CD8- T cells, in addition to a lower frequency of IFN-γ+ TIGIT- CD8+/CD8- T cells, suggestive of impaired T cell functionality. At single T cell transcriptome and clonal resolution, the patients show CD4+ T cell anergy, characterised by a lack of T cell activation and lymphoproliferative response. These findings suggest that PD-1 and TIGIT play a pivotal role in VL-HIV chronicity, and may be further explored for patient risk stratification. Our findings provide a strong rationale for adjunctive immunotherapy for the treatment of chronic VL-HIV patients to break the recurrent disease cycle.

Leishmania and HIV co-infection: first naturally Leishmania strain presenting decreased susceptibility to miltefosine, recovered from a patient in Portugal

BACKGROUND

In Europe, up to 70% of visceral leishmaniasis (VL) cases occurring in adults living with HIV. People living with HIV with VL co-infection often display persistent parasitemia, requiring chronic intermittent anti-Leishmania therapies. Consequently, frequent VL relapses and higher mortality rates are common in these individuals. As such, it is of paramount importance to understand the reasons for parasite persistence to improve infection management.

METHODS

To outline possible causes for treatment failure in the context of HIV-VL, we followed a person living with HIV-VL co-infection for nine years in a 12-month period. We characterized: HIV-related clinicopathological alterations (CD4+ T counts and viremia) and Leishmania-specific seroreactivity, parasitemia, quantification of pro-inflammatory cytokines upon stimulation and studied a Leishmania clinical isolate recovered during this period.

RESULTS

The subject presented controlled viremia and low CD4+ counts. The subject remained PCR positive for Leishmania and also seropositive. The cellular response to parasite antigens was erratic. The isolate was identified as the first Leishmania infantum case with evidence of decreased miltefosine susceptibility in Portugal.

CONCLUSION

Treatment failure is a multifactorial process driven by host and parasite determinants. Still, the real-time determination of drug susceptibility profiles in clinical isolates is an unexplored resource in the monitoring of VL.

Vaccine value profile for leishmaniasis

Leishmania infections are global, occurring in 98 countries and all World Health Organization (WHO) regions with 600 million to 1 billion people at risk of infection. Visceral leishmaniasis is associated with almost 20,000 reported deaths annually, with children under 5 years of age being at the greatest risk of mortality. Amongst WHO-recognised Neglected Tropical Diseases (NTDs), leishmaniasis is one of the most important in terms of mortality and morbidity. With an increasing global burden of disease and a growing threat from climate change, urbanisation and drug resistance, there remains an imperative to develop leishmaniasis vaccines. New tools to understand correlates of protection and to assess vaccine efficacy are being developed to ease the transition into larger scale efficacy trials or provide alternate routes to licensure. Early indications suggest a diverse portfolio of manufacturers exists in endemic countries with an appetite to develop leishmaniasis vaccines. This Vaccine Value Profile (VVP) provides a high-level, comprehensive assessment of the currently available data to inform the potential public health, economic, and societal value of leishmaniasis vaccines. The leishmaniasis VVP was developed by a working group of subject matter experts from academia, public health groups, policy organizations, and non-profit organizations. All contributors have extensive expertise on various elements of the leishmaniasis VVP and have collectively described the state of knowledge and identified the current gaps. The VVP was developed using only existing and publicly available information.

2-Aroyl quinazolinone: Synthesis and in vitro anti-parasitic activity

Trypanosomes and Leishmania are parasitic protozoans that affect millions of people globally. Herein we report the synthesis of 2-aroyl quinazolinones and their antiprotozoal efficacy against Trypanosoma brucei, Trypanosoma brucei rhodesiense, Trypanosoma cruzi, and Leishmania infantum. These compounds were counter-screened against a human cell line for cytotoxicity. Thirteen of the twenty target compounds in this study inhibited the growth of these parasites, with compounds KJ1, and KJ10 exhibiting IC50 values of 4.7 μM (T. b. brucei) and 1.1 μM (T. b. rhodesiense), respectively.

In vitro and in vivo therapeutic antileishmanial potential of ellagic acid against Leishmania donovani in murine model

Parasite of genus Leishmania viz. L. donovani and L. infantum cause visceral leishmaniasis (VL) or Kala-azar, systemic disease with significant enlargement of the liver and spleen, weight loss, anemia, fever and immunosuppression. The silent expansion of vectors, reservoir hosts and resistant strains is also of great concern in VL control. Considering all these issues, the present study focused on in vitro and in vivo antileishmanial screening of ellagic acid (EA) against L. donovani. The in vitro study was performed against the protozoan parasite L. donovani and a 50% inhibitory concentration was calculated. The DNA arrest in the sub-G0/G1 phase of the cell cycle was studied. In vivo studies included the assessment of parasite burden and immunomodulation in response to treatment of ellagic acid in BALB/c mice. The levels of Th1 and Th2 cytokines and isotype antibodies were assessed in different groups of mice. EA showed in vitro parasiticidal activity with IC₅₀ 18.55 µg/mL and thwarted cell-cycle progression at the sub-G0/G1 phase. Administration of ellagic acid to the BALB/c mice reported diminution of splenic and hepatic parasite burden coupled with an expansion of CD4⁺ and CD8⁺ T lymphocytes. EA further potentiated a protective immune response with augmentation of Th1 type immune response evidenced by elevation of serum IgG2a levels and DTH response. EA was reported to be safe and non-toxic to the THP-1 cell line as well as to the liver and kidneys of mice. These findings endorse the therapeutic potential of EA with significant immunomodulation and can serve as a promising agent against this debilitating parasitic disease.

Combined immunotherapeutic effect of Leishmania-derived recombinant aldolase and Ambisome against experimental visceral leishmaniasis

BACKGROUND

Available therapeutics for visceral leishmaniasis (VL), a deadly parasitic infection, are usually associated with inadequate efficacy and adverse aftereffects. Further, the primary site of Leishmania parasite are host macrophages resulting in compromised immunity; ensuing marked T-cell immunosuppression. Such settings emphasize the exploration of chemo-immunotherapeutic strategies for improvising the infected person's immune status with better resolution of infection.

METHODS

Present work employs the immunization of Leishmania-infected hamsters with Leishmania-derived recombinant aldolase (rLdAld) and enolase (rLdEno) proteins in consort with the sub-optimal dose of Ambisome (2.5 mg/kg). After the completion of immunization, hamsters were sacrificed on day 60 and 90 post infection and different organ samples were collected to perform immunological assay for evaluating the therapeutic efficacy and modulation in protective cellular immune responses.

RESULTS

Combining these proteins, particularly rLdAld with Ambisome (2.5 mg/kg), has significantly reduced the parasitic load (∼80%) with remarkable enhancement in DTH and lymphoproliferative responses compared to the infected control and only Ambisome treated groups. Moreover, cytokine levels at RNA and protein levels were noticed to be inclined towards Th-1 phenotype through up-regulation of IFN-γ and TNF-α with significant down-regulation in IL-10 and TGF-β expression, an indication towards the generation of protective immunity against experimental VL.

CONCLUSION

Our experimental findings demonstrated that the chemo-immunotherapeutic approach could be an effective way of controlling human VL infection at minimal dosages of antileishmanial with reduced side-effects and propensity of drug resistance emergence.

Knowledge, Attitude, and Practices among HIV/Leishmaniasis Co-Infected Patients in Bihar, India

Visceral leishmaniasis (VL) is a serious public health concern in the Indian state of Bihar, which has been exacerbated by an increasing HIV/AIDS incidence that has resulted in poor clinical outcomes. So far, there has been no investigation into the knowledge, attitude, and practices (KAP) of people who have been subjected to hospital-based supervision for VL or HIV/VL co-infection. This study assessed the KAP toward VL infection among 210 VL-infected patients (126 participants with VL and 84 participants with HIV/VL) using a pretested standard questionnaire. The findings are summarized descriptively and KAP scores are classified dichotomously (good/poor). Multivariable logistic regression and bivariate correlation were used in the analysis. The study showed that both VL-infected and co-infected patients exhibited similar deficits in KAP scores toward VL. The HIV/VL participants who had a personal or family history of VL were more likely to have appropriate awareness of and preventive practices toward VL. The independent predictors of attitude index in HIV/VL participants were education, VL family history, and marital status. There was a weak but significant positive correlation between knowledge and practice (rs = 0.321, p<0.001), and attitude and practice (rs = 0.294, p<0.001), while knowledge was strongly correlated with attitude (rs = 0.634, p<0.001). Based on the study findings, it is recommended that treatment programs in Bihar should concentrate on strengthening KAP among VL and HIV/VL co-infected patients to prevent reinfection-related complications. Behavior change communication intervention is ideal for tackling this problem. This proposal entails building a comprehensive public health program in endemic regions.

Comparison of serum cytokine levels in symptomatic and asymptomatic HIV-Leishmania coinfected individuals from a Brazilian visceral leishmaniasis endemic area

Background

Visceral leishmaniasis (VL) remains an important infectious disease worldwide. VL-HIV coinfected individuals can present with atypical clinical forms of VL and have a high risk of VL relapse. Some cytokines have been described as potential markers to diagnose active VL and to predict the severity of the cases. However, few studies have included VL-HIV coinfected patients. We aimed to characterize the levels of several cytokines among VL-HIV coinfected individuals living in a VL-endemic area in Northeast Brazil.

Methods

This was a retrospective, cross-sectional study, aiming to estimate the levels of various cytokines in symptomatic and asymptomatic VL-HIV coinfected individuals. There were 134 study participants (35 symptomatic VL-HIV, 75 asymptomatic VL-HIV, and 24 healthy controls), all ≥ 18 years-old. Serum cytokine levels (interferon-γ, tumor necrosis factor, and interleukins 2, 4, 6, 10, and 17A) were quantified using the Becton Dickinson-BD’s Cytometric Bead Array (CBA) system.

Results

The population mainly consisted of men (64.9%), with a median age of 35 (27–41) years. Asymptomatic individuals were younger (p = 0.013), with more years of education (p < 0.001), and were more often on antiretroviral therapy (p < 0.001) than those in the symptomatic group. Hemoglobin levels (p < 0.001), lymphocytes (p < 0.001) and CD4 count (p < 0.001) were lower in symptomatic individuals, while HIV viral loads were higher (p < 0.001). In the symptomatic VL-HIV coinfected group, we observed increased serum levels of IL-17A, IL-6, and IL-10 compared to asymptomatic patients and the healthy controls. There were no differences in the levels of all cytokines between asymptomatic VL-HIV coinfected individuals and the healthy controls.

Conclusions

Higher serum levels of IL-17A, IL-6, and IL-10 cytokines were observed in symptomatic coinfected individuals but not in asymptomatically infected individuals. More studies among HIV-positive persons are needed to better understand the role of serum cytokines for prognosis, to define cure and predict VL relapses in VL-HIV coinfected individuals.

Visceral leishmaniasis (VL) is a parasitic disease, classified as a neglected disease by the World Health Organization. It is present in more than 60 countries in four continents, with most tropical and subtropical countries affected. Without treatment, the disease is fatal. HIV-positive persons are especially affected by VL, with a worst prognosis. One of the main complications is the frequent reactivation of the disease even after successful treatment (VL relapse). Up to now, it is not clear why and when these reactivations occur, and many researches are trying to find some biological markers to answer this. Cytokines are one of these markers that may explain the progression of the disease. In this study, we compared the level of several key cytokines in symptomatic VL-HIV coinfected patients, asymptomatic VL-HIV coinfected individuals, and healthy controls living in a VL-endemic region in Northeastern Brazil. The serum cytokine levels were higher in symptomatic patients when compared with asymptomatic and healthy controls. More studies following VL-HIV patients are necessary to understand how these cytokines and the other biomarkers vary over time and whether they can predict VL relapse, and also the progression and the prognosis of the disease.

Knowledge, attitude and practices towards visceral leishmaniasis among HIV patients: A cross-sectional study from Bihar, India

Background

In the Indian state of Bihar, visceral leishmaniasis (VL) is a major public health issue that has been aggravated by the rising incidence of new Human immunodeficiency virus (HIV) infections. In endemic areas, the risk of VL infections in patients living with HIV (PLHIV) is higher. It is important to investigate the disease-related knowledge, attitude, and practices (KAP) of PLHIV in Bihar in order to monitor HIV/VL co-infection. Adequate knowledge, a positive attitude, and good practices for VL control are essential to stamp out the disease. This study investigated the KAP towards VL in HIV patients attending antiretroviral therapy (ART) clinic at ICMR-RMRIMS, Patna.

Methods

A questionnaire based cross-sectional study was performed among 120 HIV patients aged ≥18 years, to evaluate their KAP regarding visceral leishmaniasis. For the KAP indicators, each correct answer received a score of 1, while unsure and incorrect responses received a score of 0. Descriptive statistics and logistic regression were used for the analysis. Data analysis was performed using Statistical Package for the Social Sciences (SPSS) version 27.

Results

The study population had a male (68.30%) preponderance with a mean age of 37.03 years ± 9.80 years of standard deviation. The majority (93.30%) of the study participants had previously heard about VL. Only 32.10% of those who had heard about VL knew that the disease was transmitted by the sandfly. Most (80.40%) of the study respondents were ignorant of the sandfly breeding grounds. The vast majority (75.90%) had no idea how to recognize sandflies and were unaware of their biting time, leishmaniasis transmission season, and preventive practices. Although PLHIV are vulnerable to VL, only 27.70% of them agreed that VL is a fatal disease if untreated, and 42.90% believed they wear not at risk of developing the disease. Regarding the control methods of sandflies, 28.60% of participants did not use any methods to avoid sandfly bites. The multivariable analysis revealed that occupation and family history were the two independent predictor variables of the knowledge index. Age and gender were significantly associated with attitude towards VL. Participants working as laborers had significantly lesser odds (AOR: 0.248, 95% CI: 0.073–0.844) to follow good preventive practices. There were significantly higher odds of having good practice among participants aged 18–40 years (AOR: 6.866, 95% CI: 1.694–27.834) and those residing in urban areas (AOR: 4.159, 95% CI: 1.317–13.139) than their peers. Overall, 27.7% of respondents were knowledgeable, 41.1% had a positive mindset, and 33.9% had strong VL preventive habits, according to the study.

Conclusion

The study determined a remarkable gap in the knowledge attitude and practices towards VL among PLHIV. This underscores the need of augmented health education initiatives for PLHIV in endemic areas for good VL awareness and preventive practices.

Low antileishmanial drug exposure in HIV-positive visceral leishmaniasis patients on antiretrovirals: an Ethiopian cohort study

Background

Despite high HIV co-infection prevalence in Ethiopian visceral leishmaniasis (VL) patients, the adequacy of antileishmanial drug exposure in this population and effect of HIV-VL co-morbidity on pharmacokinetics of antileishmanial and antiretroviral (ARV) drugs is still unknown.

Methods

HIV-VL co-infected patients received the recommended liposomal amphotericin B (LAmB) monotherapy (total dose 40 mg/kg over 24 days) or combination therapy of LAmB (total dose 30 mg/kg over 11 days) plus 28 days 100 mg/day miltefosine, with possibility to extend treatment for another cycle. Miltefosine, total amphotericin B and ARV concentrations were determined in dried blood spots or plasma using LC–MS/MS.

Results

Median (IQR) amphotericin B C_max on Day 1 was 24.6 μg/mL (17.0–34.9 μg/mL), which increased to 40.9 (25.4–53.1) and 33.2 (29.0–46.6) μg/mL on the last day of combination and monotherapy, respectively. Day 28 miltefosine concentration was 18.7 (15.4–22.5) μg/mL. Miltefosine exposure correlated with amphotericin B accumulation. ARV concentrations were generally stable during antileishmanial treatment, although efavirenz C_min was below the 1 μg/mL therapeutic target for many patients.

Conclusions

This study demonstrates that antileishmanial drug exposure was low in this cohort of HIV co-infected VL patients. Amphotericin B C_max was 2-fold lower than previously observed in non-VL patients. Miltefosine exposure in HIV-VL co-infected patients was 35% lower compared with adult VL patients in Eastern Africa, only partially explained by a 19% lower dose, possibly warranting a dose adjustment. Adequate drug exposure in these HIV-VL co-infected patients is especially important given the high proportion of relapses.

Serious adverse events following treatment of visceral leishmaniasis: A systematic review and meta-analysis

Background

Despite a historical association with poor tolerability, a comprehensive review on safety of antileishmanial chemotherapies is lacking. We carried out an update of a previous systematic review of all published clinical trials in visceral leishmaniasis (VL) from 1980 to 2019 to document any reported serious adverse events (SAEs).

Methods

For this updated systematic review, we searched the following databases from 1^st Jan 2016 through 2^nd of May 2019: PUBMED, Embase, Scopus, Web of Science, Cochrane, clinicaltrials.gov, WHO ICTRP, and the Global Index Medicus. We included randomised and non-randomised interventional studies aimed at assessing therapeutic efficacy and extracted the number of SAEs reported within the first 30 days of treatment initiation. The incidence rate of death (IRD) from individual treatment arms were combined in a meta-analysis using random effects Poisson regression.

Results

We identified 157 published studies enrolling 35,376 patients in 347 treatment arms. Pentavalent antimony was administered in 74 (21.3%), multiple-dose liposomal amphotericin B (L-AmB) in 52 (15.0%), amphotericin b deoxycholate in 51 (14.7%), miltefosine in 33 (9.5%), amphotericin b fat/lipid/colloid/cholesterol in 31 (8.9%), and single-dose L-AmB in 17 (4.9%) arms. There was a total of 804 SAEs reported of which 793 (including 428 deaths) were extracted at study arm level (11 SAEs were reported at study level only). During the first 30 days, there were 285 (66.6%) deaths with the overall IRD estimated at 0.068 [95% confidence interval (CI): 0.041–0.114; I² = 81.4%; 95% prediction interval (PI): 0.001–2.779] per 1,000 person-days at risk; the rate was 0.628 [95% CI: 0.368–1.021; I² = 82.5%] in Eastern Africa, and 0.041 [95% CI: 0.021–0.081; I² = 68.1%] in the Indian Subcontinent. In 21 study arms which clearly indicated allowing the inclusion of patients with HIV co-infections the IRD was 0.575 [95% CI: 0.244–1.355; I² = 91.9%] compared to 0.043 [95% CI: 0.020–0.090; I² = 62.5%] in 160 arms which excluded HIV co-infections.

Conclusion

Mortality within the first 30 days of VL treatment initiation was a rarely reported event in clinical trials with an overall estimated rate of 0.068 deaths per 1,000 person-days at risk, though it varied across regions and patient populations. These estimates may serve as a benchmark for future trials against which mortality data from prospective and pharmacovigilance studies can be compared. The methodological limitations exposed by our review support the need to assemble individual patient data (IPD) to conduct robust IPD meta-analyses and generate stronger evidence from existing trials to support treatment guidelines and guide future research.

Visceral leishmaniasis, also known as Kala-Azar, is a neglected infectious disease of poverty affecting countries in the Indian Subcontinent and Eastern Africa. Existing treatments have concerning safety profiles and are far from ideal, with documented reports of serious adverse events (SAEs) following therapy. We did a systematic review of all published clinical trials in VL (1980–2019) to document SAEs following treatment administration reported in clinical literature and carried out a meta-analysis to quantify the incidence rate of mortality within 30 days of treatment initiation. We found that safety outcomes are poorly reported in published literature with substantial missing information regarding timing and frequency of the events. We also observed that mortality following treatment with antileishmanial drugs, as reported in the literature, is a rare event. There was substantial variability in mortality rates across geographical regions and patient sub-groups. Results from this review can provide benchmark estimates for comparing data from prospective trials and pharmacovigilance studies and support the need to assemble individual patient data (IPD) to conduct a robust IPD meta-analyses to overcome some of the underlying limitations.

Leucocytes and Th-associated Cytokine Profile of HIV-Leishmaniasis Co-Infected Persons Attending Abuja Teaching Hospital, Nigeria

Objective

T-helper cells (Th)-1& -2 cytokines homeostasis control or predict clinical outcome of infected persons, especially those with HIV /AIDS. This case-control study evaluated the leucocytes differentials, TNF-alpha, interleukin (IL)-2 and -10 levels among HIV infected persons with serological evidence of leishmaniasis attending University of Abuja Teaching Hospital, Nigeria.

Materials and Methods

Blood samples from 28 HIV infected persons who had Leishmania donovani rK39 and Immunoglobulin-G (IgG) positive (group 1), 30 age- & -sex matched HIV infected persons without Leishmania antibodies (group 2) and 30 apparently healthy persons without HIV and Leishmania antibodies (group 3). Full blood counts, TNF alpha, IL-2 and -10 levels were analyzed using automated hematology analyzer and ELISA, respectively. Structured questionnaires were used to collate biodata and clinical presentations of participants.

Results

Ten (35.7%) participants in group 1 were on ART, 15 (50%) in group 2 were on ART, while group 3 were ART naïve. There were significantly higher values in basophil (4.4±2.5%) and eosinophil counts (12.9±3.8%) in HIV/leishmania coinfected persons (p<0.005). However, other white cells subpopulation was significantly lower in HIV/leishmania co-infected participants (p<0.05). There was significantly reduced CD4+ T cell counts ([119±26 versus 348±63 versus 605±116 cells/mm3]), TNF-alpha ([36.82±8.21 versus 64.67±12.54 versus 254.98±65.59 pg/mL]) and IL-2 levels ([142.14±20.91 versus 507.6±84.42 versus 486.62±167.87 pg/mL]) among HIV/Leishmania co-infected participants compared to group 2 and group 3 participants, respectively. However, higher IL-10 level (80.35±14.57 pg/mL) was found in HIV/Leishmania co-infected participants as opposed to the HIV monoinfected (62.2±10.43 pg/mL) and apparently healthy persons (23.97±4.88 pg/mL) (p<0.001).

Conclusion

Eosinophil, basophil counts and serum IL-10 level were high in HIV/Leishmania coinfected persons, demonstrating parasite-induced hypersensitivity and immunosuppression.

Leishmaniasis immunopathology-impact on design and use of vaccines, diagnostics and drugs

Leishmaniasis is a disease complex caused by 20 species of protozoan parasites belonging to the genus Leishmania. In humans, it has two main clinical forms, visceral leishmaniasis (VL) and cutaneous or tegumentary leishmaniasis (CL), as well as several other cutaneous manifestations in a minority of cases. In the mammalian host Leishmania parasites infect different populations of macrophages where they multiply and survive in the phagolysosomal compartment. The progression of both VL and CL depends on the maintenance of a parasite-specific immunosuppressive state based around this host macrophage infection. The complexity and variation of immune responses and immunopathology in humans and the different host interactions of the different Leishmania species has an impact upon the effectiveness of vaccines, diagnostics and drugs.

Study of therapeutic effect of different concentrations of imatinib on Balb/c model of cutaneous leishmaniasis

Leishmaniasis, as a tropical and subtropical disease, is endemic in more than 90 countries around the world. Today, cutaneous leishmaniasis (CL) that affects more than 1.5 million people per year lacks a definitive treatment approach. Imatinib is an anticancer drug that inhibits the abnormal function of Bcr-Abl due to its tyrosine kinase inhibitor, and that was the reason why the drug was tested for CL treatment because protein kinases are essential enzymes in the Leishmania genus. In this study, the L. major CL model of Balb/c mice was produced by injection of the cultured metacyclic form of parasite at the base of the tail. The possible recovery of CL ulcers and determination of the optimum dose of imatinib against Leishmania amastigotes were evaluated. A significant decrease was observed in mice treated with amphotericin B (positive control group) as well as imatinib 50 mg/kg compared to the unreceived drug, negative control group (P<0.05). This study could be promising in gaining insight into the potential of imatinib as an effective treatment approach against CL.

In vitro and in vivo immunomodulatory properties of octyl-β-D-galactofuranoside during Leishmania donovani infection

BACKGROUND

The chemotherapeutic arsenal available to treat visceral leishmaniasis is currently limited, in view of many drawbacks such as high cost, toxicity or emerging resistance. New therapeutic strategies are particularly needed to improve the management and the outcome in immunosuppressed patients. The combination of an immunomodulatory drug to a conventional anti-Leishmania treatment is an emerging concept to reverse the immune bias from Th2 to Th1 response to boost healing and prevent relapses.

METHODS

Here, immunostimulating and leishmanicidal properties of octyl-β-D-galactofuranose (Galf) were assessed in human monocyte-derived macrophages (HM) and in a murine model, after challenge with Leishmania donovani promastigotes. We recorded parasite loads and expression of various cytokines and immune effectors in HM and mouse organs (liver, spleen, bone marrow), following treatment with free (Galf) and liposomal (L-Galf) formulations.

RESULTS

Both treatments significantly reduced parasite proliferation in HM, as well as liver parasite burden in vivo (Galf, P < 0.05). Consistent with in vitro results, we showed that Galf- and L-Galf-treated mice displayed an enhanced Th1 immune response, particularly in the spleen where pro-inflammatory cytokines TNF-α, IL-1β and IL-12 were significantly overexpressed compared to control group. The hepatic recruitment of myeloid cells was also favored by L-Galf treatment as evidenced by the five-fold increase of myeloperoxidase (MPO) induction, which was associated with a higher number of MPO-positive cells within granulomas. By contrast, the systemic level of various cytokines such as IL-1β, IL-6, IL-17A or IL-27 was drastically reduced at the end of treatment.

CONCLUSIONS

Overall, these results suggest that Galf could be tested as an adjuvant in combination with current anti-parasitic drugs, to restore an efficient immune response against infection in a model of immunosuppressed mice.

[Periodic fever and pancytopenia in a 35-year-old patient]

MEDICAL HISTORY AND INITIAL PRESENTATION

A 35-year-old patient with a previous history of persistent episodic fever, sore throat, myalgia, and cephalgia presented for evaluation of pancytopenia. He had no recent travel history, except for a stay in Italy 1 year prior to admission and in Spain several years in the past.

DIAGNOSTIC WORKUP

Laboratory evaluation confirmed pancytopenia, agranulocytosis, and elevated infection parameters without indicative serological results en par with lymphadenitis colli. Computed tomography scanning revealed cervical lymphadenopathy, hepatosplenomegaly, and colitis with occult perforation of the sigmoid colon. Bone marrow biopsy showed an infiltration of polyclonal plasma cells. Lymph node biopsy was compatible with necrotizing lymphadenitis.

DIAGNOSIS

Polymerase chain reaction analysis of a lymph node specimen confirmed the presence of Leishmania species, thereby enabling the diagnosis of visceral Leishmania.

THERAPY COURSE

Treatment with liposomal amphotericin B was initiated. Both fever and lymphadenopathy quickly resolved.

CONCLUSION

VL is a clinically pleiotropic, severe disease with fatal outcome if left untreated. It often presents with distinct similarities to hematologic malignancies. Exacerbation can occasionally occur as fulminant macrophage activation syndrome. Disease incidence is globally increasing and has not peaked as yet. A complex interplay between pathogen and the immune system is the key pathophysiological mechanism.

Miltefosine-Lopinavir Combination Therapy Against Leishmania infantum Infection: In vitro and in vivo Approaches

Concurrently, leishmaniasis and AIDS are global public health issues and the overlap between these diseases adds additional treats to the management of co-infected patients. Lopinavir (LPV) has a well characterized anti-HIV and leishmanicidal action, and to analyze its combined action with miltefosine (MFS) could help to envisage strategies to the management of co-infected patients. Here, we evaluate the interaction between LPV and MFS against Leishmania infantum infection by in vitro and in vivo approaches. The effect of the compounds alone or in association was assessed for 72 h in mouse peritoneal macrophages infected with L. infantum by the determination of the IC₅₀s and FICIs. Subsequently, mice were orally treated twice daily during 5 days with the compounds alone or in association and evaluated after 30 days. The in vitro assays revealed an IC₅₀ of 0.24 μM and 9.89 μM of MFS and LPV, respectively, and an additive effect of the compounds (FICI 1.28). The in vivo assays revealed that LPV alone reduced the parasite load in the spleen and liver by 52 and 40%, respectively. The combined treatment of infected BALB/c mice revealed that the compounds alone required at least two times higher doses than when administered in association to virtually eliminate the parasite. Mice plasma biochemical parameters assessed revealed that the combined therapy did not present any relevant hepatotoxicity. In conclusion, the association of MFS with LPV allowed a reduction in each compound concentration to achieve the same outcome in the treatment of visceral leishmaniasis. Although a pronounced synergistic effect was not evidenced, it does not discard that such combination could be useful in humans co-infected with HIV and Leishmania parasites.

Systematic Review of Host-Mediated Activity of Miltefosine in Leishmaniasis through Immunomodulation

Host immune responses are pivotal for the successful treatment of the leishmaniases, a spectrum of infections caused by Leishmania parasites. Previous studies speculated that augmenting cytokines associated with a type 1 T-helper cell (Th1) response is necessary to combat severe forms of leishmaniasis, and it has been hypothesized that the antileishmanial drug miltefosine is capable of immunomodulation and induction of Th1 cytokines.

Host immune responses are pivotal for the successful treatment of the leishmaniases, a spectrum of infections caused by Leishmania parasites. Previous studies speculated that augmenting cytokines associated with a type 1 T-helper cell (Th1) response is necessary to combat severe forms of leishmaniasis, and it has been hypothesized that the antileishmanial drug miltefosine is capable of immunomodulation and induction of Th1 cytokines. A better understanding of the immunomodulatory effects of miltefosine is central to providing a rationale regarding synergistic mechanisms of activity to combine miltefosine optimally with other conventional and future antileishmanials that are currently under development. Therefore, a systematic literature search was performed to evaluate to what extent and how miltefosine influences the host Th1 response. Miltefosine’s effects observed in both a preclinical and a clinical context associated with immunomodulation in the treatment of leishmaniasis are evaluated in this review. A total of 27 studies were included in the analysis. Based on the current evidence, miltefosine is not only capable of inducing direct parasite killing but also of modulating the host immunity. Our findings suggest that miltefosine-induced activation of Th1 cytokines, particularly represented by increased gamma interferon (IFN-γ) and interleukin 12 (IL-12), is essential to prevail over the Leishmania-driven Th2 response. Differences in miltefosine-induced host-mediated effects between in vitro, ex vivo, animal model, and human studies are further discussed. All things considered, an effective treatment with miltefosine is acquired by enhanced functional Th1 cytokine responses and may further be enhanced in combination with immunostimulatory agents.

Asymptomatic immune responders to Leishmania among HIV positive patients

Concomitant infection with human immunodeficiency virus (HIV) and the Leishmania parasite is a growing public health problem, the result of the former spreading to areas where the latter is endemic. Leishmania infection is usually asymptomatic in immunocompetent individuals, but the proportion of HIV+ individuals in contact with the parasite who remain asymptomatic is not known. The aim of the present work was to examine the use of cytokine release assays in the detection of asymptomatic immune responders to Leishmania among HIV+ patients with no previous leishmaniasis or current symptomatology. Eighty two HIV+ patients (all from Fuenlabrada, Madrid, Spain, where a leishmaniasis outbreak occurred in 2009) were examined for Leishmania infantum infection using molecular and humoral response-based methods. None returned a positive molecular or serological result for the parasite. Thirteen subjects showed a positive lymphoproliferative response to soluble Leishmania antigen (SLA), although the mean CD4+ T lymphocyte counts of these patients was below the normal range. Stimulation of peripheral blood mononuclear cells (PBMC) or whole blood with SLA (the lymphoproliferative assay and whole blood assay respectively), led to the production of specific cytokines and chemokines. Thus, despite being immunocompromised, HIV+ patients can maintain a Th1-type cellular response to Leishmania. In addition, cytokine release assays would appear to be useful tools for detecting these individuals via the identification of IFN-γ in the supernatants of SLA-stimulated PBMC, and of IFN-γ, MIG and IL-2 in SLA-stimulated whole blood. These biomarkers appear to be 100% reliable for detecting asymptomatic immune responders to Leishmania among HIV+ patients.

The proportion of patients with HIV+ who have at some time been infected with the Leishmania parasite, but who remain asymptomatic, is unknown. It is important to be able to identify such patients to determine the prevalence of asymptomatic leishmaniasis in the HIV+ population, and because these persons are at increased risk of developing symptomatic visceral leishmaniasis. In the present work, a population of HIV+ patients showing a cellular immune response to Leishmania infantum was identified. These subjects all showed a clear Th1-type response when their PBMC or blood were stimulated in vitro with soluble Leishmania antigen (SLA). Cytokine release assays and the detection of IFN-γ, MIG and IL-2 (specific biomarkers for immunity to Leishmania) were found to be useful for detecting this population of HIV+ patients. New studies with larger numbers of patients are needed to confirm the present results.

Treatment of toxoplasmosis: Current options and future perspectives

Toxoplasmosis is a worldwide parasitic disease infecting about one third of humans, with possible severe outcomes in neonates and immunocompromised patients. Despite continuous and successful efforts to improve diagnosis, therapeutic schemes have barely evolved since many years. This article aims at reviewing the main clinical trials and current treatment practices, and at addressing future perspectives in the light of ongoing researches.

The criminal association of Leishmania parasites and viruses

In nature, humans infected with protozoan parasites can encounter viruses, which could alter their host immune response. The impact of viruses on human parasitic diseases remains largely unexplored due to the highly sterilized environment in experimental studies and the difficulty to draw a correlation between co-infection and pathology. Recent studies show that viral infections exacerbate pathology and promote dissemination of some Leishmania infections, based on a hyper-inflammatory reaction driven by type I interferons. Thus, not only the infecting parasite species, but also bystander viral infections could be a major determinant of the outcome of Leishmania infection. In this review, we focus on the contribution of viral co-infection to the exacerbation of leishmaniasis's pathology and its possible impact on treatment and vaccination strategies.