Assessing the Efficacy and Safety of Liposomal Amphotericin B and Miltefosine in Combination for Treatment of Post Kala-Azar Dermal Leishmaniasis

Antimony susceptible Leishmania donovani: evidence from in vitro drug susceptibility of parasites isolated from patients of post-kala-azar dermal leishmaniasis in pre- and post-miltefosine era

Post-kala-azar dermal leishmaniasis (PKDL) patients are a key source of Leishmania donovani parasites, hindering the goal of eliminating visceral leishmaniasis (VL). Monitoring treatment response and parasite susceptibility is essential due to increasing drug resistance. We assessed the drug susceptibility of PKDL isolates (n = 18) from pre-miltefosine (MIL) era (1997-2004) with isolates (n = 16) from the post-miltefosine era (2010-2019) and post-miltefosine treatment relapse isolates (n = 5) towards miltefosine and amphotericin B (AmB) at promastigote stage and towards sodium antimony gluconate (SAG) at amastigote stage. PKDL isolates were examined for mutation in gene-encoding AQP1 transporter, C26882T mutation on chromosome 24, and miltefosine-transporter (MT). PKDL isolates from the post-miltefosine era were significantly more susceptible to SAG than SAG-resistant isolates from the pre-miltefosine era (P = 0.0002). There was no significant difference in the susceptibility of parasites to miltefosine between pre- and post-miltefosine era isolates. The susceptibility of PKDL isolates towards AmB remained unchanged between the pre- and post-miltefosine era. However, the post-miltefosine era isolates had a higher IC50 value towards AmB compared with PKDL relapse isolates. We did not find any association between AQP1 gene sequence variation and susceptibility to SAG, or between miltefosine susceptibility and single nucleotide polymorphisms (SNPs in the MT gene. This study demonstrates that recent isolates of Leishmania have resumed susceptibility to antimonials in vitro. The study also offers significant insights into the intrinsic drug susceptibility of Leishmania parasites over the past two decades, covering the period before the introduction of miltefosine and after its extensive use.

IMPORTANCE

Post-kala-azar dermal leishmaniasis (PKDL) patients, a key source of Leishmania donovani parasites, hinder eliminating visceral-leishmaniasis. Assessment of the susceptibility of PKDL isolates to antimony, miltefosine (MIL), and amphotericin-B indicated that recent isolates remain susceptible to antimony, enabling its use with other drugs for treating PKDL.

Post-kala-azar dermal leishmaniasis (PKDL) drug efficacy study landscape: A systematic scoping review of clinical trials and observational studies to assess the feasibility of establishing an individual participant-level data (IPD) platform

BACKGROUND

Post-kala-azar dermal leishmaniasis (PKDL) is a dermatosis which can occur after successful treatment of visceral leishmaniasis (VL) and is a public health problem in VL endemic areas. We conducted a systematic scoping review to assess the characteristics of published PKDL clinical studies, understand the scope of research and explore the feasibility and value of developing a PKDL individual patient data (IPD) platform.

METHODS

A systematic review of published literature was conducted to identify PKDL clinical studies by searching the following databases: PubMed, Scopus, Ovid Embase, Web of Science Core Collection, WHO Global Index Medicus, PASCAL, Clinicaltrials.gov, Ovid Global Health, Cochrane Database and CENTRAL, and the WHO International Clinical Trials Registry Platform. Only prospective studies in humans with PKDL diagnosis, treatment, and follow-up measurements between January 1973 and March 2023 were included. Extracted data includes variables on patient characteristics, treatment regimens, diagnostic methods, geographical locations, efficacy endpoints, adverse events and statistical methodology.

RESULTS

A total of 3,418 records were screened, of which 56 unique studies (n = 2,486 patients) were included in this review. Out of the 56 studies, 36 (64.3%) were from India (1983-2022), 12 (21.4%) from Sudan (1992-2021), 6 (10.7%) were from Bangladesh (1991-2019), and 2 (3.6%) from Nepal (2001-2007). Five (8.9%) studies were published between 1981-1990 (n = 193 patients), 10 (17.9%) between 1991-2000 (n = 230 patients), 10 (17.9%) between 2001-2010 (n = 198 patients), and 31 (55.4%) from 2011 onwards (n = 1,865 patients). Eight (14.3%) were randomised clinical trials, and 48 (85.7%) were non-randomised studies. The median post-treatment follow-up duration was 365 days (range: 90-540 days) in 8 RCTs and 360 days (range: 28-2,373 days) in 48 non-randomised studies. Disease diagnosis was based on clinical criterion in 3 (5.4%) studies, a mixture of clinical and parasitological methods in 47 (83.9%) and was unclear in 6 (10.7%) studies. Major drugs used for treatment were miltefosine (n = 636 patients), liposomal amphotericin B (L-AmB) (n = 508 patients), and antinomy regimens (n = 454 patients). Ten other drug regimens were tested in 270 patients with less than 60 patients per regimen.

CONCLUSIONS

Our review identified studies with very limited sample size for the three major drugs (miltefosine, L-AmB, and pentavalent antimony), while the number of patients combined across studies suggest that the IPD platform would be valuable. With the support of relevant stakeholders, the global PKDL community and sufficient financing, a PKDL IPD platform can be realised. This will allow for exploration of different aspects of treatment safety and efficacy, which can potentially guide future healthcare decisions and clinical practices.

Safety and efficacy of paromomycin/miltefosine/liposomal amphotericin B combinations for the treatment of post-kala-azar dermal leishmaniasis in Sudan: A phase II, open label, randomized, parallel arm study

BACKGROUND

Treatment for post-kala-azar dermal leishmaniasis (PKDL) in Sudan is currently recommended only for patients with persistent or severe disease, mainly because of the limitations of current therapies, namely toxicity and long hospitalization. We assessed the safety and efficacy of miltefosine combined with paromomycin and liposomal amphotericin B (LAmB) for the treatment of PKDL in Sudan.

METHODOLOGY/PRINCIPAL FINDINGS

An open-label, phase II, randomized, parallel-arm, non-comparative trial was conducted in patients with persistent (stable or progressive disease for ≥ 6 months) or grade 3 PKDL, aged 6 to ≤ 60 years in Sudan. The median age was 9.0 years (IQR 7.0-10.0y) and 87% of patients were ≤12 years old. Patients were randomly assigned to either daily intra-muscular paromomycin (20mg/kg, 14 days) plus oral miltefosine (allometric dose, 42 days)-PM/MF-or LAmB (total dose of 20mg/kg, administered in four injections in week one) and oral miltefosine (allometric dose, 28 days)-LAmB/MF. The primary endpoint was a definitive cure at 12 months after treatment onset, defined as clinical cure (100% lesion resolution) and no additional PKDL treatment between end of therapy and 12-month follow-up assessment. 104/110 patients completed the trial. Definitive cure at 12 months was achieved in 54/55 (98.2%, 95% CI 90.3-100) and 44/55 (80.0%, 95% CI 70.2-91.9) of patients in the PM/MF and AmB/MF arms, respectively, in the mITT set (all randomized patients receiving at least one dose of treatment; in case of error of treatment allocation, the actual treatment received was used in the analysis). No SAEs or deaths were reported, and most AEs were mild or moderate. At least one adverse drug reaction (ADR) was reported in 13/55 (23.6%) patients in PM/MF arm and 28/55 (50.9%) in LAmB/MF arm, the most frequent being miltefosine-related vomiting and nausea, and LAmB-related hypokalaemia; no ocular or auditory ADRs were reported.

CONCLUSIONS/SIGNIFICANCE

The PM/MF regimen requires shorter hospitalization than the currently recommended 60-90-day treatment, and is safe and highly efficacious, even for patients with moderate and severe PKDL. It can be administered at primary health care facilities, with LAmB/MF as a good alternative. For future VL elimination, we need new, safe oral therapies for all patients with PKDL.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03399955, https://clinicaltrials.gov/study/NCT03399955 ClinicalTrials.gov ClinicalTrials.gov.

Barriers to the effective management and prevention of post kala-azar dermal leishmaniasis (PKDL) in the Indian subcontinent

Post kala-azar dermal leishmaniasis (PKDL) is a skin disease that usually occurs among individuals with a past history of visceral leishmaniasis (VL). PKDL cases act as a reservoir of parasites and may play a significant role in disease transmission. Hence, prompt detection and complete treatment of PKDL cases are crucial for the control and elimination of VL. The purpose of this review was to highlight the barriers to effective control and prevention of VL/PKDL as well as potential solutions in India. Main obstacles are lack of knowledge about the disease and its vector, poor treatment-seeking behaviours, ineffective vector control measures, lack of confirmatory diagnostics in endemic areas, limited drug choices, treatment noncompliance among patients, drug resistance, and a lack of an adequate number of trained personnel in the health system. Therefore, in order to control and successfully eliminate VL in the Indian subcontinent, early detection of PKDL cases, improved diagnosis and treatment, raising awareness, and effective vector control mechanisms are necessary.

Post kala-azar dermal leishmaniasis in the Indian sub-continent: challenges and strategies for elimination

Visceral leishmaniasis (VL) is a severe and often fatal form of leishmaniasis caused by Leishmania donovani in the Indian sub-continent. Post Kala-azar Dermal Leishmaniasis (PKDL) is a late cutaneous manifestation of VL, typically occurring after apparent cure of VL, but sometimes even without a prior history of VL in India. PKDL serves as a significant yet neglected reservoir of infection and plays a crucial role in the transmission of the disease, posing a serious threat to the VL elimination program in the Indian sub-continent. Therefore, the eradication of PKDL should be a priority within the current VL elimination program aimed at achieving a goal of less than 1 case per 10,000 in the population at the district or sub-district levels of VL endemic areas. To accomplish this, a comprehensive understanding of the pathogenesis of PKDL is essential, as well as developing strategies for disease management. This review provides an overview of the current status of diagnosis and treatment options for PKDL, highlighting our current knowledge of the immune responses underlying disease development and progression. Additionally, the review discusses the impact of PKDL on elimination programs and propose strategies to overcome this challenge and achieve the goal of elimination. By addressing the diagnostic and therapeutic gaps, optimizing surveillance and control measures, and implementing effective intervention strategies, it is possible to mitigate the burden of PKDL and facilitate the successful elimination of VL in the Indian sub-continent.

Safety and Effectiveness of Miltefosine in Post-Kala-Azar Dermal Leishmaniasis: An Observational Study

Background

Post-kala-azar dermal leishmaniasis (PKDL) is a dermal complication of visceral leishmaniasis. Oral miltefosine (MF) is the first-line treatment for PKDL patients in South Asia. This study assessed the safety and effectiveness of MF therapy after 12 months of follow-up to explore more precise data.

Methods

In this observational study, 300 confirmed PKDL patients were enrolled. MF with the usual dose was administered to all patients for 12 weeks and followed up for 1 year. Clinical evolution was recorded systematically by photographs at screening and at 12 weeks, 6 months, and 12 months after treatment onset. Definitive cure consisted of disappearance of skin lesions with a negative PCR at 12 weeks or with >70% of lesions, disappearing or fading at 12-month follow-up. Patients with reappearing clinical features and any positive diagnostics of PKDL during the follow-up were considered as nonresponsive.

Results

Among 300 patients, 286 (95.3%) completed 12 weeks of treatment. The per-protocol cure rate at 12 months was 97%, but 7 patients relapsed and 51 (17%) were lost to 12-month follow-up, resulting in a final cure rate of only 76%. Eye-related adverse events were noted in 11 (3.7%) patients and resolved in most (72.7%) within 12 months. Unfortunately, 3 patients had persistent partial vision loss. Mild to moderate gastrointestinal side effects were seen in 28% patients.

Conclusions

Moderate effectiveness of MF was observed in the present study. A significant number of patients developed ocular complications, and thus MF for treatment for PKDL should be suspended and replaced with a safer alternative regimen.

In vitro anti-Leishmania activity of triclabendazole and its synergic effect with amphotericin B

Introduction

Leishmaniasis is a neglected tropical disease, with approximately 1 million new cases and 30,000 deaths reported every year worldwide. Given the lack of adequate medication for treating leishmaniasis, drug repositioning is essential to save time and money when searching for new therapeutic approaches. This is particularly important given leishmaniasis's status as a neglected disease. Available treatments are still far from being fully effective for treating the different clinical forms of the disease. They are also administered parenterally, making it challenging to ensure complete treatment, and they are extremely toxic, in some cases, causing death. Triclabendazole (TCBZ) is a benzimidazole used to treat fasciolosis in adults and children. It presents a lower toxicity profile than amphotericin B (AmpB) and is administered orally, making it an attractive candidate for treating other parasitoses. The mechanism of action for TCBZ is not yet well understood, although microtubules or polyamines could potentially act as a pharmacological target. TCBZ has already shown antiproliferative activity against T. cruzi, T. brucei, and L. infantum. However, further investigations are still necessary to elucidate the mechanisms of action of TCBZ.

Methods

Cytotoxicity assay was performed by MTT assay. Cell inhibition (CI) values were obtained according to the equation CI = (O.D treatment x 100/O.D. negative control). For Infection evaluation, fixated cells were stained with Hoechst and read at Operetta High Content Imaging System (Perkin Elmer). For growth curves, cell culture absorbance was measured daily at 600 nm. For the synergism effect, Fractional Inhibitory Concentrations (FICs) were calculated for the IC50 of the drugs alone or combined. Mitochondrial membrane potential (DYm), cell cycle, and cell death analysis were evaluated by flow cytometry. Reactive oxygen species (ROS) and lipid quantification were also determined by fluorimetry. Treated parasites morphology and ultrastructure were analyzed by electron microscopy.

Results

The selectivity index (SI = CC50/IC50) of TCBZ was comparable with AmpB in promastigotes and amastigotes of Leishmania amazonensis. Evaluation of the cell cycle showed an increase of up to 13% of cells concentrated in S and G2, and morphological analysis with scanning electron microscopy showed a high frequency of dividing cells. The ultrastructural analysis demonstrated large cytoplasmic lipid accumulation, which could suggest alterations in lipid metabolism. Combined administration of TCBZ and AmpB demonstrated a synergistic effect in vitro against intracellular amastigote forms with cSFICs of 0.25.

Conclusions

Considering that TCBZ has the advantage of being inexpensive and administrated orally, our results suggest that TCBZ, combined with AmpB, is a promising candidate for treating leishmaniasis with reduced toxicity.

Immune recovery-related patterns of post kala-azar dermal and ocular leishmaniasis in people living with HIV

OBJECTIVE

Post kala-azar dermal leishmaniasis (PKDL) is a rare complication of visceral leishmaniasis. We aimed at reporting PKDL cases in people living with HIV (PLHIV) and compare their characteristics based on whether PKDL occurred in the context of immune recovery under antiretroviral therapy (ART) or not.

DESIGN

National survey and literature review.

METHODS

We called for observations in France in October 2020 and performed a literature review from PubMed (Medline) and Web of Science up to December 2020. Two groups of patients were defined based on whether PKDL occurred in the context of immune recovery under ART (group 1) or not (group 2), and compared.

RESULTS

Three PLHIV with PKDL identified in France in the last decade were described and added to 33 cases from the literature. Compared with group 2 (16/36, 44.4%), patients from group 1 (20/36, 55.6%) originated more frequently from Europe (12/20, 60% vs. 2/16, 12.5%; P  = 0.0038), had higher median blood CD4 + cell counts (221/μl vs. 61/μl; P  = 0.0005) and increase under ART (122/μl, interquartile range 73-243 vs. 33/μl, interquartile range 0-53; P  = 0.0044), had less frequently concomitant visceral leishmaniasis (3/20, 15% vs. 8/12, 66.7%; P  = 0.006), and a trend to more frequent ocular involvement (7/20, 35% vs. 1/16, 6.25%; P  = 0.0531).

CONCLUSION

In PLHIV, PKDL occurs after a cured episode of visceral leishmaniasis as part of an immune restoration disease under ART, or concomitant to a visceral leishmaniasis relapse in a context of AIDS. For the latter, the denomination 'disseminated cutaneous lesions associated with visceral leishmaniasis' seems more accurate than PKDL.

Translating diagnostics and drug delivery technologies to low-resource settings

Diagnostics and drug delivery technologies engineered for low-resource settings aim to meet their technical design specifications using strategies that are compatible with limited equipment, infrastructure, and operator training. Despite many preclinical successes, very few of these devices have been translated to the clinic. Here, we identify factors that contribute to the clinical success of diagnostics and drug delivery systems for low-resource settings, including the need to engage key stakeholders at an early stage, and provide recommendations for the clinical translation of future medical technologies.

Leishmaniasis and Chagas disease: Is there hope in nanotechnology to fight neglected tropical diseases?

Nanotechnology is revolutionizing many sectors of science, from food preservation to healthcare to energy applications. Since 1995, when the first nanomedicines started being commercialized, drug developers have relied on nanotechnology to improve the pharmacokinetic properties of bioactive molecules. The development of advanced nanomaterials has greatly enhanced drug discovery through improved pharmacotherapeutic effects and reduction of toxicity and side effects. Therefore, highly toxic treatments such as cancer chemotherapy, have benefited from nanotechnology. Considering the toxicity of the few therapeutic options to treat neglected tropical diseases, such as leishmaniasis and Chagas disease, nanotechnology has also been explored as a potential innovation to treat these diseases. However, despite the significant research progress over the years, the benefits of nanotechnology for both diseases are still limited to preliminary animal studies, raising the question about the clinical utility of nanomedicines in this field. From this perspective, this review aims to discuss recent nanotechnological developments, the advantages of nanoformulations over current leishmanicidal and trypanocidal drugs, limitations of nano-based drugs, and research gaps that still must be filled to make these novel drug delivery systems a reality for leishmaniasis and Chagas disease treatment.

Advancement in leishmaniasis diagnosis and therapeutics: An update

Leishmaniasis is regarded as a neglected tropical disease by World Health Organization (WHO) and is ranked next to malaria as the deadliest protozoan disease. The primary causative agents of the disease comprise of diverse leishmanial species sharing clinical features ranging from skin abrasions to lethal infection in the visceral organs. As several Leishmania species are involved in infection, the role of accurate diagnosis becomes pivotal in adding new dimensions to anti-leishmanial therapy. Diagnostic methods must be fast, reliable, easy to perform, highly sensitive, and specific to differentiate among similar parasitic diseases. Herein, we present the conventional and recent approaches impended for the disease diagnosis and their sensitivity, specificity, and clinical application in parasite detection. Furthermore, we have also elaborated various new methods to cure leishmaniasis, which include host-directed therapies, drug repurposing, nanotechnology, and combinational therapy. This review addresses novel techniques and innovations in leishmaniasis, which can aid in unraveling new strategies to fight against the deadly infection.

Utility of Blood as the Clinical Specimen for the Molecular Diagnosis of Post-Kala-Azar Dermal Leishmaniasis

The countries in the Indian subcontinent have reported a dramatic decline in visceral leishmaniasis (VL) cases. However, the presence of the parasite reservoir in the form of post-kala-azar dermal leishmaniasis (PKDL), a dermal sequel of VL, is a hurdle in attaining VL elimination. Presently employed clinical specimens for the diagnosis of PKDL include skin biopsy specimens and slit skin smears. In this study, the use of blood as a clinical specimen was investigated in different manifestations of PKDL in India. This is a bicentric study (National Institute of Pathology, Indian Council of Medical Research [ICMR], New Delhi, and Institute of Medical Sciences [IMS], Banaras Hindu University, Varanasi), with 215 participants (120 PKDL patients and 95 controls). Highly sensitive quantitative real-time PCR (Q-PCR) and field-deployable loop-mediated isothermal amplification (LAMP) were employed using blood samples for diagnosis. Promising sensitivities of 77.50% (95% confidence interval [CI], 69.24 to 84.05%) for Q-PCR and 70.83% (95% CI, 62.16 to 78.22%) for LAMP were obtained for the diagnosis of PKDL. Further, enhanced sensitivities of 83.33% (95% CI, 71.28 to 90.98%) and 77.78% (95% CI, 65.06 to 86.80%) for Q-PCR and LAMP, respectively, were recorded for the detection of macular cases. The study revealed an inverse correlation between the parasite load estimated in slit and blood samples, thereby favoring the use of blood for the diagnosis of the macular variant, which may be missed due to scant parasite loads in the slit. This study is the first to propose the promising potential of blood as a clinical specimen for accurate diagnosis of PKDL, which would aid in fast-tracking VL elimination.

ENTPDases from Pathogenic Trypanosomatids and Purinergic Signaling: Shedding Light towards Biotechnological Applications

ENTPDases are enzymes known for hydrolyzing extracellular nucleotides and playing an essential role in controlling the nucleotide signaling via nucleotide/purinergic receptors P2. Moreover, ENTPDases, together with Ecto-5´-nucleotidase activity, affect the adenosine signaling via P1 receptors. These signals control many biological processes, including the immune system. In this context, ATP is considered as a trigger to inflammatory signaling, while adenosine (Ado) induces anti-inflammatory response. The trypanosomatids Leishmania and Trypanosoma cruzi, pathogenic agents of Leishmaniasis and Chagas Disease, respectively, have their own ENTPDases named "TpENTPDases," which can affect the nucleotide signaling, adhesion and infection, in order to favor the parasite. Besides, TpENTPDases are essential for the parasite nutrition, since the Purine De Novo synthesis pathway is absent in them, which makes these pathogens dependent on the intake of purines and nucleopurines for the Salvage Pathway, in which TpENTPDases also take place. Here, we review information regarding TpNTPDases, including their known biological roles and their effect on the purinergic signaling. We also highlight the roles of these enzymes in parasite infection and their biotechnological applications, while pointing to future developments.

Comparative EPR spectroscopy analysis of amphotericin B and miltefosine interactions with Leishmania, erythrocyte and macrophage membranes

Electron paramagnetic resonance (EPR) spectroscopy of spin labels was used to study the interactions of amphotericin B (AmB) with the plasma membrane of Leishmania (L.) amazonensis promastigotes, human erythrocytes and J774.A1 murine macrophages, in comparison with reported and novel data for miltefosine (MIL). One of the objectives of this work is to look for the relationships between the activities of these two drugs in the Leishmania parasite with their changes in the cell membrane. A spin-labeled stearic acid inserted into the cell membranes showed strong interactions with putative AmB/sterol complexes, characterized by reductions in molecular dynamics. The concentration of the drugs in the plasma membrane that reduced the cell population by 50%, and the membrane-water partition coefficient of the drugs, were assessed. These biophysical parameters enabled estimates of possible therapeutic concentrations of these two drugs in the interstitial fluids of the tissues to be made. AmB displayed higher affinity for the plasma membrane of L. amazonensis than for that of the macrophage and erythrocyte, denoting a preference for a membrane that contains ergosterol. AmB also demonstrated higher hemolytic potential than MIL for measurements on erythrocytes in both PBS and whole blood. For MIL, the EPR technique detected membrane changes induced by the drug in the same concentration range that inhibited the growth of parasites, but in the case of AmB, an 8-fold higher concentration of the IC₅₀ was necessary to observe a reduction in membrane fluidity, suggesting a better localized effect of AmB on the membrane. Taken together, the results demonstrate that the antiproliferative and cytotoxic effects of both drugs are associated with changes in cell membranes.

Real-Time Fluorimetry Loop-Mediated Isothermal Amplification for Diagnosis of Leishmaniasis and as a Tool for Assessment of Cure for Post-Kala-Azar Dermal Leishmaniasis

Despite the dwindling number of visceral leishmaniasis (VL) cases in India, there is an urgent need for early and unequivocal diagnostics for controlling and preventing the reemergence of VL. Post-kala-azar dermal leishmaniasis (PKDL), a dermal sequela of VL, serves as a reservoir of the parasite. Diagnosis of PKDL, especially the macular variant, is challenging and poses impediment toward attainment of VL elimination. In this study, a real-time fluorimetry loop-mediated isothermal amplification (RealAmp) assay has been established for the detection of different clinical manifestations of leishmaniasis. The study included 150 leishmaniasis patients (25 VL, 25 cutaneous leishmaniasis [CL], and 100-PKDL) along with 120 controls. The assay demonstrated sensitivity of 100% (95% CI: 86.68-100) for diagnosis of VL and PKDL (95% CI: 79.61-100) and 96% (95% CI: 86.68-100) for CL with 100% specificity. Moreover, considering the cardinal role of PKDL, diagnosis using minimally invasive slit aspirate was explored, which demonstrated remarkable sensitivity of 96% (95% CI: 87.64-98.47). As a test of cure for PKDL, RealAmp successfully detected parasite in two of posttreatment cases who later reported relapse on follow-up. Also, direct sample lysis using slit aspirate was attempted in a small group that yielded sensitivity of 89% (95% CI: 67.20-96.90). RealAmp depicted excellent diagnostic accuracy in the diagnosis of leishmaniasis in concordance with the established SYBR Green I-based visual loop-mediated isothermal amplification (LAMP) and the reference comparator real-time PCR. The study endorsed the employment of LAMP either as visual-LAMP or RealAmp for an accurate and expeditious diagnosis of PKDL and as a tool for assessment of cure.

Drug combinations as effective anti-leishmanials against drug resistant Leishmania mexicana

Leishmania is a parasite that causes the disease leishmaniasis, and 700 000 to 1 million new cases occur each year. There are few drugs that treat the disease and drug resistance in the parasite limits the clinical utility of existing drugs. One way to combat drug resistance is to use combination therapy rather than monotherapy. In this study we have compared the effect of single and combination treatments with four different compounds, i.e. alkylphosphocholine analogues APC12 and APC14, miltefosine (MIL), ketoconazole (KTZ), and amphotericin B (AmpB), on the survival of Leishmania mexicana wild-type promastigotes and a cell line derived from the WT with induced resistance to APC12 (C12Rx). The combination treatment with APC14 and APC16 had a synergistic effect in killing the WT while the combination treatment with KTZ and APC12 or APC14 or APC12 and APC14 had a synergistic effect against C12Rx. More than 90% killing efficiency was obtained using APC12 alone at >1 mg ml^-1 against the C12Rx strain; however, combinations with APC14 produced a similar killing efficiency using APC12 at 0.063-0.25 mg ml^-1 and APC14 at 0.003-0.5 mg ml^-1. These results show that combination therapy can negate induced drug resistance in L. mexicana and that the use of this type of screening system could accelerate the development of drug combinations for clinical use.

A clioquinol-containing Pluronic® F127 polymeric micelle system is effective in the treatment of visceral leishmaniasis in a murine model

A clioquinol (ICHQ)-containing Pluronic^® F127 polymeric micelle system (ICHQ/Mic) was recently shown to be effective against Leishmania amazonensis infection in a murine model. In the present study, ICHQ/Mic was tested against L. infantum infection. BALB/c mice (n = 12 per group) were infected with L. infantum stationary promastigotes through subcutaneous injection and, 45 days after challenge, received saline or were treated via the subcutaneous route with empty micelles, ICHQ or ICHQ/Mic. In addition, animals were treated with miltefosine by the oral route, as a drug control. Half of the animals were euthanized 1 and 15 days after treatment, aiming to evaluate two endpoints after therapy, when parasitological and immunological parameters were investigated. Results showed that the treatment using miltefosine, ICHQ or ICHQ/Mic induced significantly higher anti-parasite IFN-γ, IL-12, GM-CSF, nitrite and IgG2a isotype antibody levels, which were associated with low IL-4 and IL-10 production. In addition, a higher frequency of IFN-γ and TNF-α-producing CD4⁺ and CD8⁺ T-cells was found in these animals. The parasite load was evaluated in distinct organs, and results showed that the treatment using miltefosine, ICHQ or ICHQ/Mic induced significant reductions in organic parasitism in the treated and infected mice. A comparison between the treatments suggested that ICHQ/Mic was the most effective in inducing a highly polarized Th1-type response, as well as reducing the parasite load in significant levels in the treated and infected animals. Data obtained 15 days after treatment suggested maintenance of the immunological and parasitological responses. In conclusion, ICHQ/Mic could be considered in future studies for the treatment of visceral leishmaniasis.

Immune Responses in Post Kala-azar Dermal Leishmaniasis

Kala-azar, commonly known as visceral leishmaniasis (VL), is a neglected tropical disease that has been targeted in South Asia for elimination by 2020. Presently, the Kala-azar Elimination Programme is aimed at identifying new low-endemic foci by active case detection, consolidating vector control measures, and decreasing potential reservoirs, of which Post Kala-azar Dermal Leishmaniasis (PKDL) is considered as the most important. PKDL is a skin condition that occurs after apparently successful treatment of VL and is characterized by hypopigmented patches (macular) or a mixture of papules, nodules, and/or macules (polymorphic). To achieve this goal of elimination, it is important to delineate the pathophysiology so that informed decisions can be made regarding the most appropriate and cost-effective approach. We reviewed the literature with regard to PKDL in Asia and Africa and interpreted the findings in establishing a potential correlation between the immune responses and pathophysiology. The overall histopathology indicated the presence of a dense, inflammatory cellular infiltrate, characterized by increased expression of alternatively activated CD68+ macrophages, CD8+ T cells showing features of exhaustion, CD20+ B cells, along with decreased CD1a+ dendritic cells. Accordingly, this review is an update on the overall immunopathology of PKDL, so as to provide a better understanding of host-parasite interactions and the immune responses generated which could translate into availability of markers that can be harnessed for assessment of disease progression and improvement of existing treatment modalities.