Blood Parasite Load as an Early Marker to Predict Treatment Response in Visceral Leishmaniasis in Eastern Africa

BACKGROUND

To expedite the development of new oral treatment regimens for visceral leishmaniasis (VL), there is a need for early markers to evaluate treatment response and predict long-term outcomes.

METHODS

Data from 3 clinical trials were combined in this study, in which Eastern African VL patients received various antileishmanial therapies. Leishmania kinetoplast DNA was quantified in whole blood with real-time quantitative polymerase chain reaction (qPCR) before, during, and up to 6 months after treatment. The predictive performance of pharmacodynamic parameters for clinical relapse was evaluated using receiver-operating characteristic curves. Clinical trial simulations were performed to determine the power associated with the use of blood parasite load as a surrogate endpoint to predict clinical outcome at 6 months.

RESULTS

The absolute parasite density on day 56 after start of treatment was found to be a highly sensitive predictor of relapse within 6 months of follow-up at a cutoff of 20 parasites/mL (area under the curve 0.92, specificity 0.91, sensitivity 0.89). Blood parasite loads correlated well with tissue parasite loads (ρ = 0.80) and with microscopy gradings of bone marrow and spleen aspirate smears. Clinical trial simulations indicated a > 80% power to detect a difference in cure rate between treatment regimens if this difference was high (> 50%) and when minimally 30 patients were included per regimen.

CONCLUSIONS

Blood Leishmania parasite load determined by qPCR is a promising early biomarker to predict relapse in VL patients. Once optimized, it might be useful in dose finding studies of new chemical entities.

Efficacy and safety of a combined treatment of sodium stibogluconate at 20mg/kg/day with upper maximum daily dose limit of 850mg and Paromomycin 15mg/kg/day in HIV negative visceral leishmaniasis patients. A retrospective study, northwest Ethiopia

BACKGROUND

Visceral leishmaniasis (VL) is one of the most neglected tropical infectious diseases. It is fatal if left untreated. The objective of this study was to assess the efficacy and safety of 17-day injections of combined regimen of sodium stibogluconate and paromomycin (SSG/PM) in HIV-negative VL patients.

METHODS

A retrospective analysis of medical records of VL patients treated in the University of Gondar Hospital during period 2012-2019 was carried out.

RESULTS

A total of 2836 patients were treated for VL from 2012 to 2019. Of these 1233 were treated with SSG-PM, and 1000 of them were included in the study. Initial cure was achieved in 922 (92.2%) patients. The frequency of treatment failure, treatment interruptions, default and deaths respectively were 30 (3%), 20 (2%), 13 (1.3%) and 15 (1.5%). Among 280 patients who completed 6-month follow up, the final cure was 93.9% (263/280), 4 (1.4%) relapsed and 13 (4.6%) developed post-kala-azar dermal leishmaniasis (PKDL). The most common adverse events (AEs) were raised liver transaminases (35.1%; 351 patients), injection site pain (29.1%, 291 patients) and raised serum alpha-amylase (29.1%, 291 patients). Factors associated with poor treatment outcomes were sepsis, pneumonia, and adverse events.

CONCLUSION

A combination of SSG at 20mg/kg with upper daily maximum dose of 850mg and PM was effective for achieving initial cure at end of treatment and safe for treatment of HIV negative VL patients in northwestern Ethiopia. Our data are consistent with previous reports and confirms effectiveness of SSG/PM treatment regimen in the Eastern African countries. Efficacy at 6-months (93.9%) was estimated on data derived from patients who completed follow up and needs to be interrogated by future studies.

Distinct Laboratory and Clinical Features of Secondary Hemophagocytic Lymphohistiocytosis in Pediatric Visceral Leishmaniasis: A Retrospective Analysis of 127 Children in Andalusia, Spain (2004-2019)

BACKGROUND

Visceral leishmaniasis (VL) is an endemic in Southern Europe. However, details regarding disease burden, clinical presentations, laboratory markers, management and outcome in children are scarce.

METHODS

Medical records of children (<14 years) admitted with VL to 10 pediatric units in Andalusia (2004-2019) were retrospectively reviewed. VL diagnosis was based on clinical presentation, serology, microscopy and molecular methods. Diagnosis of secondary hemophagocytic lymphohistiocytosis (sHLH) was established using the hemophagocytic lymphohistiocytosis-2004 criteria.

RESULTS

A total of 127 patients were identified. Median age was 14.5 months; the main clinical presentations were fever and splenomegaly (95.3% each). Cytopenias were the most common laboratory abnormalities. Diagnostics as well as treatment regimens varied over time and the participating centers. Liposomal amphotericin B was prescribed in 97.6%; relapses as well as adverse events were rarely observed (3.1% each). Thirty-seven patients, diagnosed with sHLH required longer hospital admission (P = 0.001), an increased number of platelet (P < 0.006) and red blood cell (P = 0.0001) transfusions and pediatric intensive care unit admission (P = 0.007). Monocytopenia (P = 0.011) and high C-reactive protein levels (P = 0.031), variables not included in the hemophagocytic lymphohistiocytosis-2004 criteria, were associated with sHLH. One patient deceased in the context of the Leishmania infection.

CONCLUSIONS

We report data on the largest pediatric VL cohort from Europe, commonly associated with sHLH. Raised C-reactive protein levels and monocytopenia appear to be associated with sHLH. The latter may help to identify these patients and to guide decisions regarding need of additional supportive clinical care and immunomodulatory therapies. The observed high rate of heterogeneity in terms of diagnosis and management warrants the establishment of appropriate guidelines.

Biogenic nanoporous silicon carrier improves the efficacy of buparvaquone against resistant visceral leishmaniasis

Visceral leishmaniasis is a vector-borne protozoan infection that is fatal if untreated. There is no vaccination against the disease, and the current chemotherapeutic agents are ineffective due to increased resistance and severe side effects. Buparvaquone is a potential drug against the leishmaniases, but it is highly hydrophobic resulting in poor bioavailability and low therapeutic efficacy. Herein, we loaded the drug into silicon nanoparticles produced from barley husk, which is an agricultural residue and widely available. The buparvaquone-loaded nanoparticles were several times more selective to kill the intracellular parasites being non-toxic to macrophages compared to the pure buparvaquone and other conventionally used anti-leishmanial agents. Furthermore, the in vivo results revealed that the intraperitoneally injected buparvaquone-loaded nanoparticles suppressed the parasite burden close to 100%. By contrast, pure buparvaquone suppressed the burden only by 50% with corresponding doses. As the conclusion, the biogenic silicon nanoparticles are promising carriers to significantly improve the therapeutic efficacy and selectivity of buparvaquone against resistant visceral leishmaniasis opening a new avenue for low-cost treatment against this neglected tropical disease threatening especially the poor people in developing nations.

Evaluation of qPCR on blood and skin microbiopsies, peripheral blood buffy coat smear, and urine antigen ELISA for diagnosis and test of cure for visceral leishmaniasis in HIV-coinfected patients in India: a prospective cohort study

INTRODUCTION

HIV coinfection presents a challenge for diagnosis of visceral leishmaniasis (VL). Invasive splenic or bone marrow aspiration with microscopic visualisation of Leishmania parasites remains the gold standard for diagnosis of VL in HIV-coinfected patients. Furthermore, a test of cure by splenic or bone marrow aspiration is required as patients with VL-HIV infection are at a high risk of treatment failure. However, there remain financial, implementation and safety costs to these invasive techniques which severely limit their use under field conditions.

METHODS AND ANALYSIS

We aim to evaluate blood and skin qPCR, peripheral blood buffy coat smear microscopy and urine antigen ELISA as non-invasive or minimally invasive alternatives for diagnosis and post-treatment test of cure for VL in HIV-coinfected patients in India, using a sample of 91 patients with parasitologically confirmed symptomatic VL-HIV infection.

ETHICS AND DISSEMINATION

Ethical approval for this study has been granted by The Liverpool School of Tropical Medicine, The Institute of Tropical Medicine in Antwerp, the University of Antwerp and the Rajendra Memorial Research Institute of Medical Science in Patna. Any future publications will be published in open access journals.

TRIAL REGISTRATION NUMBER

CTRI/2019/03/017908.

Dissecting pathways to thrombocytopenia in a mouse model of visceral leishmaniasis

Visceral leishmaniasis is an important yet neglected parasitic disease caused by infection with Leishmania donovani or L infantum. Disease manifestations include fever, weight loss, hepatosplenomegaly, immune dysregulation, and extensive hematological complications. Thrombocytopenia is a dominant hematological feature seen in both humans and experimental models, but the mechanisms behind this infection-driven thrombocytopenia remain poorly understood. Using a murine model of experimental visceral leishmaniasis (EVL), we demonstrated a progressive decrease in platelets from day 14 after infection, culminating in severe thrombocytopenia by day 28. Plasma thrombopoietin (TPO) levels were reduced in infected mice, at least in part because of the alterations in the liver microenvironment associated with granulomatous inflammation. Bone marrow (BM) megakaryocyte cytoplasmic maturation was significantly reduced. In addition to a production deficit, we identified significant increases in platelet clearance. L donovani-infected splenectomized mice were protected from thrombocytopenia compared with sham operated infected mice and had a greater response to exogenous TPO. Furthermore, infection led to higher levels of platelet opsonization and desialylation, both associated with platelet clearance in spleen and liver, respectively. Critically, these changes could be reversed rapidly by drug treatment to reduce parasite load or by administration of TPO agonists. In summary, our findings demonstrate that the mechanisms underpinning thrombocytopenia in EVL are multifactorial and reversible, with no obvious residual damage to the BM microenvironment.

Pharmacokinetic / pharmacodynamic relationships of liposomal amphotericin B and miltefosine in experimental visceral leishmaniasis

BACKGROUND

There is a continued need to develop effective and safe treatments for visceral leishmaniasis (VL). Preclinical studies on pharmacokinetics and pharmacodynamics of anti-infective agents, such as anti-bacterials and anti-fungals, have provided valuable information in the development and dosing of these agents. The aim of this study was to characterise the pharmacokinetic and pharmacodynamic properties of the anti-leishmanial drugs AmBisome and miltefosine in a preclinical disease model of VL.

METHODOLOGY / PRINCIPAL FINDINGS

BALB/c mice were infected with L. donovani (MHOM/ET/67/HU3) amastigotes. Groups of mice were treated with miltefosine (orally, multi-dose regimen) or AmBisome (intravenously, single dose regimen) or left untreated as control groups. At set time points groups of mice were killed and plasma, livers and spleens harvested. For pharmacodynamics the hepatic parasite burden was determined microscopically from tissue impression smears. For pharmacokinetics drug concentrations were measured in plasma and whole tissue homogenates by LC-MS. Unbound drug concentrations were determined by rapid equilibrium dialysis. Doses exerting maximum anti-leishmanial effects were 40 mg/kg for AmBisome and 150 mg/kg (cumulatively) for miltefosine. AmBisome displayed a wider therapeutic range than miltefosine. Dose fractionation at a total dose of 2.5 mg/kg pointed towards concentration-dependent anti-leishmanial activity of AmBisome, favouring the administration of large doses infrequently. Protein binding was >99% for miltefosine and amphotericin B in plasma and tissue homogenates.

CONCLUSION / SIGNIFICANCE

Using a PK/PD approach we propose optimal dosing strategies for AmBisome. Additionally, we describe pharmacokinetic and pharmacodynamic properties of miltefosine and compare our findings in a preclinical disease model to available knowledge from studies in humans. This approach also presents a strategy for improved use of animal models in the drug development process for VL.

Gender disparity in cases enrolled in clinical trials of visceral leishmaniasis: A systematic review and meta-analysis

BACKGROUND

A higher caseload of visceral leishmaniasis (VL) has been observed among males in community-based surveys. We carried out this review to investigate how the observed disparity in gender distribution is reflected in clinical trials of antileishmanial therapies.

METHODS

We identified relevant studies by searching a database of all published clinical trials in VL from 1980 through 2019 indexed in the Infectious Diseases Data Observatory (IDDO) VL clinical trials library. The proportion of male participants enrolled in studies eligible for inclusion in this review were extracted and combined using random effects meta-analysis of proportion. Results were expressed as percentages and presented with respective 95% confidence intervals (95% CIs). Heterogeneity was quantified using I2 statistics and sub-group meta-analyses were carried out to explore the sources of heterogeneity.

RESULTS

We identified 135 published studies (1980-2019; 32,177 patients) with 68.0% [95% CI: 65.9%-70.0%; I2 = 92.6%] of the enrolled participants being males. The corresponding estimates were 67.6% [95% CI: 65.5%-69.7%; n = 91 trials; I2 = 90.5%; 24,218 patients] in studies conducted in the Indian sub-continent and 74.1% [95% CI: 68.4%-79.1%; n = 24 trials; I2 = 94.4%; 6,716 patients] in studies from Eastern Africa. The proportion of male participants was 57.9% [95% CI: 54.2%-61.5%] in studies enrolling children aged <15 years, 78.2% [95% CI: 66.0%-86.9%] in studies that enrolled adults (≥15 years), and 68.1% [95% CI: 65.9%-70.0%] in studies that enrolled patients of all ages. There was a trend for decreased proportions of males enrolled over time: 77.1% [95% CI: 70.2%-82.8%; 1356 patients] in studies published prior to the 1990s whereas 64.3% [95% CI: 60.3%-68.2%; 15,611 patients] in studies published on or after 2010. In studies that allowed the inclusion of patients with HIV co-infections, 76.5% [95% CI: 63.8%-85.9%; 5,123 patients] were males and the corresponding estimate was 64.0% [95% CI: 61.4%-66.5% 17,500 patients] in studies which excluded patients with HIV co-infections.

CONCLUSIONS

Two-thirds of the participants enrolled in clinical studies in VL conducted in the past 40 years were males, though the imbalance was less in children and in more recent trials. VL treatment guidelines are informed by the knowledge of treatment outcomes from a population that is heavily skewed towards adult males. Investigators planning future studies should consider this fact and ensure approaches for more gender-balanced inclusion.

3,5-Dimethyl-4-isoxazoyl selenocyanate as promising agent for the treatment of Leishmania infantum-infected mice

Compounds 1 and 2 (selenocyanate and diselenide derivatives, respectively) were evaluated for their potential use in vivo against visceral leishmaniasis (VL). Both entities showed low cytoxicity in vitro in Vero and Caco-2 cell lines. However, the compounds were not suitable for their oral administration, since they exhibited poor values of intestinal permeability in vitro. Microsomal stability assays did not show any metabolite for compound 1 after 120 min, whereas 2 was highly metabolized by the enzyme CYP450. Thus, the in vivo efficacy of compound 1 was assessed in a murine model of L. infantum VL. The daily i.v. administration of 1 mg/kg of compound 1 during 5 consecutive days reduced parasite load in liver, spleen and bone marrow (99.2%, 91.7% and 61.4%, respectively) compared to non-treated mice. To the best of our knowledge, this is the first time that a selenium compound has been tested in vivo against VL. Thus, this work evidences the possible usefulness of selenocyanate derivatives for the treatment of this disease.

Leishmaniasis in Norway

BACKGROUND

Leishmaniasis is a rare but potentially severe tropical infectious disease, and Norwegian clinicians are generally unfamiliar with its diagnosis and treatment. This study aimed to investigate the number of cases diagnosed, performance of diagnostic methods and treatment of leishmaniasis at five university hospitals in Norway.

MATERIAL AND METHOD

The number of cases, diagnosis and treatment of suspected leishmaniasis were registered prospectively in the period March 2014 - September 2017 at the university hospitals of Bergen, Oslo, Stavanger, Trondheim and Tromsø.

RESULTS

A total of 13 patients with leishmaniasis were registered in the period. Visceral leishmaniasis was diagnosed in two patients infected in the Mediterranean region, after 7 and 8 weeks with symptoms. The diagnosis was made by serology as well as microscopy and/or polymerase chain reaction tests (PCR) on spleen, blood and bone marrow. Both patients were treated effectively with liposomal amphotericin B. Cutaneous leishmaniasis was diagnosed in 11 patients, and samples from 10 of these tested positive with PCR. Two patients were infected with potentially mucotropic species. Liposomal amphotericin B was the first-line choice for all those who received treatment, but one patient recovered only after local therapy with sodium stibogluconate.

INTERPRETATION

Assessment of visceral leishmaniasis was undertaken according to international guidelines. The patients were diagnosed late in the disease course, presumably because the disease is rare and not well known in Norway. Cutaneous leishmaniasis was diagnosed with PCR, but none of the patients received local treatment as the first-line choice, as recommended in suitable cases, presumably because the drugs are not readily available in Norway and many clinicians are unfamiliar with the route of administration with local infiltration.

Antileishmanial activity of fullerol and its liposomal formulation in experimental models of visceral leishmaniasis

Visceral leishmaniasis (VL) is a systemic parasitic disease that leads to high rates of morbidity and mortality in humans worldwide. There is a great need to develop new drugs and novel strategies to make chemotherapy for this disease more efficacious and well tolerated. Recent reports on the immunomodulatory effects and the low toxicity of the spherical carbon nanostructure fullerol led us to investigate in vitro and in vivo antileishmanial activity in free and encapsulated forms in liposomes. When assayed against intramacrophagic Leishmania amastigotes, fullerol showed a dose-dependent reduction of the infection index with IC50 of 0.042 mg/mL. When given daily by i.p. route for 20 days (0.05 mg/kg/d) in a murine model of acute VL, fullerol promoted significant reduction in the liver parasite load. To improve the delivery of fullerol to the infection sites, liposomal formulations were prepared by the dehydration-rehydration method. When evaluated in the acute VL model, liposomal fullerol (Lip-Ful) formulations given i.p. at 0.05 and 0.2 mg/kg with 4-days intervals were more effective than the free form, with significant parasite reductions in both liver and spleen. Lip-Ful at 0.2 mg/kg promoted complete parasite elimination in the liver. The antileishmanial activity of Lip-Ful was further confirmed in a chronic model of VL. Lip-Ful was also found to induce secretion of pro-inflammatory TNF-α, IFN-γ and IL-1β cytokines. In conclusion, this work reports for the first time the antileishmanial activity of fullerol and introduces an innovative approach for treatment of VL based on the association of this nanostructure with liposomes.

Synergic effect of eugenol oleate with amphotericin B augments anti-leishmanial immune response in experimental visceral leishmaniasis in vitro and in vivo

Present treatment regimen on visceral leishmaniasis has multiple limitations including severe side effects, toxicity, and resistance of Leishmania strains. Amphotericin B is a well-established pharmacologically approved drug; however, mainly toxicity is a foremost issue with that drug. Recently, our group identified eugenol oleate as an anti-leishmanial immunomodulatory compound. The important objectives of this present study was to evaluate the possible synergistic effect of eugenol oleate with amphotericin B to reduce the toxicity of this approved drug. Results obtained from this study signified that combination of eugenol oleate and amphotericin B showed indifferent combinatorial effect against promastigotes with xΣFIC 1.015, while, moderate synergistic activity with xΣFIC 0.456 against amastigotes. It was also notable that eugenol oleate (2.5 μM) with low concentrations of amphotericin B (0.3125 μM) showed 96.45% parasite reduction within L. donovani-infected murine macrophages. Furthermore, eugenol oleate and amphotericin B significantly (p < 0.01) enhanced the nitrite generation, and pro-inflammatory cytokines (IL-12, IFN-γ and TNF-α) in infected macrophages in vitro and in BALB/c mice in vivo. Eugenol oleate (10 mg/Kg b. wt.) with amphotericin B (1 mg/Kg b.wt.) significantly (p < 0.01) controlled the parasite burden in liver by 96.2% and in spleen by 93.12%. Hence, this study strongly suggested the synergic potential of eugenol oleate with low concentration of amphotericin B in experimental visceral leishmaniasis through anti-leishmanial immune response.

Skin maculae, chronic diarrhea, cachexia, and splenomegaly-Late presentation of the first autochthonous case of visceral leishmaniasis in Tanzania

A 20-year-old man from Simanjiro district in northern Tanzania presented with a 3-year history of splenomegaly, fatigue, cachexia, skin maculae, and recent onset of watery diarrhea at Kilimanjaro Christian Medical Centre (KCMC) in Northern Tanzania. Due to laboratory findings of pancytopenia, diagnostic workup included bone marrow aspiration cytology and biopsy. Although the rapid test (IT LEISH, rK39 RDT) was negative, blood smear showed amastigote forms of leishmaniasis in macrophages. Repeat bone marrow aspiration and PCR eventually confirmed visceral leishmaniasis (VL). The patient denied travel to known endemic areas of VL. Treatment was initiated with Amphotericin B, but the patient died on the fourth day of treatment from respiratory insufficiency. An autopsy revealed massive organ manifestations of VL. This is the first reported autochthonous case of VL in Tanzania. Clark and colleagues detected the vector Phlebotomus martini in Northern Tanzania in 2013, in a region bordering the district of our patient. The negative rapid test draws attention to the fact that sensitivity and specificity were found to be low in East African VL patients as displayed earlier by a Kenyan study. Therefore, tissue samples (spleen or bone marrow) remain necessary for diagnosis. The variety of symptoms in this presented case was remarkable, including the occurrence of post-kala-azar dermal leishmaniasis (PKDL) and VL at the same time. This has been described in East African VL cases before as well as the occurrence of chronic diarrhea. An elongated undiagnosed period likely led to a mixed clinical picture that included hepato-splenomegaly, PKDL, cachexia, and diarrhea.

Lupeol and amphotericin B mediate synergistic anti-leishmanial immunomodulatory effects in Leishmania donovani-infected BALB/c mice

Leishmania donovani, a protozoan parasite, inflicts the disease Visceral leishmaniasis (VL) Worldwide. The only orally bioavailable drug miltefosine is toxic, whereas liposomal amphotericin B (AmpB) is expensive. Lupeol, a triterpenoid from Sterculia villosa bark, was exhibited immunomodulatory and anti-leishmanial activity in experimental VL. Herein, we evaluated synergism between sub-optimum dose of AmpB and lupeol in anti-leishmanial and immunomodulatory effects in L. donovani-infected BALB/c mice. We observed that a combination of sub-optimum dose of lupeol and AmpB significantly reduced the hepatic and splenic parasitic burden accompanied by enhanced nitric oxide production, robust induction of Th1 cytokines (IL-12 and IFN-γ) but suppressed Th2 cytokine (IL-10 and TGF- β) production. The treatment with the lupeol-AmpB combination enhanced p38mitogen-activated protein kinase (p38MAPK), but reduced extracellular signal-related kinase (ERK-1/2), phosphorylation and up-regulated pro-inflammatory response. The present work thus indicates a lupeol-AmpB-mediated immunotherapeutic approach for eliminating the parasite-induced immunosuppression.

Potential of Artesunate in the treatment of visceral leishmaniasis in dogs naturally infected by Leishmania infantum: Efficacy evidence from a randomized field trial

Leishmaniasis is among the world’s most neglected diseases. Dogs are the main reservoirs/hosts of Leishmania infantum, causative agent of both canine and human visceral leishmaniosis. Canine leishmaniasis (CanL) represents a public health problem as one of the most prevalent zoonotic diseases worldwide. Current therapeutics present drawbacks; thus, there is a need for more effective, safer, and cheaper drugs. The aim of this study was to evaluate and to compare the efficacy of oral administration of artesunate or meglumine antimoniate/allopurinol in dogs with clinical leishmaniasis. Forty-two dogs with naturally occurring clinical leishmaniasis were included in this open-label, simple randomized positive-control clinical field trial with 6 months of follow-up. Dogs received meglumine antimoniate 100 mg/kg/day and allopurinol 30 mg/kg/day for 28 days (control group, n = 26) or artesunate 25 mg/kg/day for 6 days (test group, n = 16). The animals were evaluated for their clinical evolution, parasite load (by qPCR) and humoral response at different time points: 0, 30, 90, and 180 days after treatment. Data analyses showed a significant improvement in both groups in clinical scores, parasitemia and antibody titers after treatment. Compared to the control group, the artesunate group showed significantly lower clinical score (P = 0.0001), lower parasitemia (P = 0.0001) and antibody titers after 6 months of follow-up. Compared to baseline values, a rapid, significant reduction (P < 0.012) in antibody levels, 2.28- versus 3.04-fold for the control versus artesunate groups, respectively, was observed 30 days after treatment. Antibody levels continued to decrease further in the artesunate group, where 58% of cases became seronegative at the 6-month follow-up. All qPCR-positive dogs were negative after treatment with artesunate, while 14.3% remained positive with the appearance of two new cases in the control group. Artesunate was well tolerated, and no side effects were recorded. Treatment failures were similar in both groups with 27.27% (6/22), including 18.18% (4/22) mortality in the control group, versus 26.66% (4/15), including 13.33% (2/15) mortality in the artesunate group. This is the first report showing the potential of artesunate in the treatment of dogs with clinical leishmaniasis. Artesunate showed higher efficacy than the current first-line treatment for CanL without any adverse effects. It could be a good alternative chemotherapy for CanL, and may be considered for further studies in human leishmaniases. Further clinical trials are needed to confirm these findings, to determine if there are relapses after treatment and if dogs remain infective to sandflies, to define the ideal therapeutic dosage and duration of treatment with artesunate.

Canine leishmaniasis (CanL) is a fatal, zoonotic vector-borne disease caused by Leishmania infantum, a common pathogen for both humans and dogs. Most CanL therapeutics are toxic, expensive, or ineffective. Artemisinin and derivatives have recently demonstrated potent antileishmanial activity in vitro and in experimental models. In this study, dogs with clinical leishmaniasis were randomly included in one of the treatment groups: meglumine antimoniate/allopurinol (control) or artesunate (alternative). Dogs were followed up for 6 months for their clinical score, parasitemia and Leishmania antibody levels. Both groups showed improved clinical scores, parasitemia and antibody titers after treatment. After six months of follow-up, treatment success was very similar in both groups, and 72.73% (16/22) of the controls versus 73.34% (11/15) in the artesunate group had clinical improvement. All dogs initially seropositive by PCR became negative after artesunate treatment, while 14.3% remained positive with the appearance of new cases in the control group. Antibody titers decreased rapidly (from day 30) from baseline especially in the artesunate group, where 58% of the dogs converted to seronegative after 6 months. Artesunate could be a good alternative for treatment of leishmaniasis. Additional clinical trials are needed to obtain more data on this drug.

Micronutrient levels and their effects on the prognosis of visceral leishmaniasis treatment, a prospective cohort study

BACKGROUND

Micronutrients are minerals and vitamins and they are essential for normal physiological activities. The objectives of the study were to describe the progress and determinants of micronutrient levels and to assess the effects of micronutrients in the treatment outcome of kalazar.

METHODS

A prospective cohort study design was used. The data were collected using patient interviews, measuring anthropometric indicators, and collecting laboratory samples. The blood samples were collected at five different periods during the leishmaniasis treatments: before starting anti-leishmaniasis treatments, in the first week, in the second week, in the third week, and in the 4th week of anti-leishmaniasis treatments. Descriptive statistics were used to describe the profile of patients and to compare the treatment success rate. The generalized estimating equation was used to identify the determinants of serum micronutrients.

RESULTS

The mean age of the patients were 32.88 years [SD (standard deviation) ±15.95]. Male constitute 62.3% of the patients and problematic alcohol use was present in 11.5% of the patients. The serum zinc level of visceral leishmaniasis patients was affected by alcohol (B - 2.7 [95% CI: - 4.01 - -1.5]), DDS (B 9.75 [95% CI: 7.71-11.79]), family size (B -1.63 [95% CI: - 2.68 - -0.58]), HIV (B -2.95 [95% CI: - 4.97 - -0.92]), and sex (B - 1.28 [95% CI: - 2.5 - -0.07]). The serum iron level of visceral leishmaniasis patients was affected by alcohol (B 7.6 [95% CI: 5.86-9.35]), family size (B -5.14 [95% CI: - 7.01 - -3.28]), malaria (B -12.69 [95% CI: - 14.53 - -10.87]), Hookworm (- 4.48 [- 6.82 - -2.14]), chronic diseases (B -7.44 [95% CI: - 9.75 - -5.13]), and HIV (B -5.51 [95% CI: - 8.23 - -2.78]). The serum selenium level of visceral leishmaniasis patient was affected by HIV (B -18.1 [95% CI: - 20.63 - -15.58]) and family size (B -11.36 [95% CI: - 13.02 - -9.7]). The iodine level of visceral leishmaniasis patient was affected by HIV (B -38.02 [95% CI: - 41.98 - -34.06]), DDS (B 25 .84 [95% CI: 22.57-29.1]), smoking (B -12.34 [95% CI: - 15.98 - -8.7]), chronic illness (B -5.14 [95% CI: - 7.82 - -2.46]), and regular physical exercise (B 5.82 [95% CI: 0.39-11.26]). The serum vitamin D level of visceral leishmaniasis patient was affected by HIV (B -9.43 [95% CI: - 10.92 - -7.94]), DDS (B 16.24 [95% CI: 14.89-17.58]), malaria (B -0.61 [95% CI: - 3.37 - -3.37]), and family size (B -1.15 [95% CI: - 2.03 - -0.28]). The serum vitamin A level of visceral leishmaniasis patient was affected by residence (B 0.81 [95% CI: 0.08-1.54]), BMI (B 1.52 [95% CI: 0.42-2.6]), DDS (B 1.62 [95% CI: 0.36-2.88]), family size (B -5.03 [95% CI: - 5.83 - -4.22]), HIV (B -2.89 [95% CI: - 4.44 - -1.34]),MUAC (B 0.86 [95% CI: 0.52-1.21]), and age (B 0.09 [95% CI: 0.07-0.12]).

CONCLUSION

The micronutrient levels of visceral leishmaniasis patients were significantly lower. The anti-leishmaniasis treatment did not increase the serum micronutrient level of the patients.

Visceral leishmaniasis in patients with lymphoma: Case reports and review of the literature

INTRODUCTION

Non-HIV-related visceral leishmaniasis (VL) is becoming increasingly prevalent in nontropical countries because of the increasing number of patients with chronic diseases and the development of immune-modulating drugs.

PATIENT CONCERNS

Case 1 is a 60-year-old male patient of Senegalese origin presented with weight loss, lymphadenopathy, anemia, and elevated lactate dehydrogenases. Case 2 is a 46-year-old male patient of Algerian origin, with a negative HIV serology presented with cutaneous lesions.

DIAGNOSIS

Patient 1: The diagnosis of stage IV lymphocytic lymphoma (LL) was confirmed by an inguinal nodal biopsy in 2013. Patient 2: The diagnosis of T-cell lymphoma was made in 2003.

INTERVENTIONS

Patient 1 received 5 cycles of bendamustine and rituximab followed by a complete remission. Patient 2 was initially treated with >10 different treatments followed by 8 different chemotherapy regimens due to the disease progression.

OUTCOMES

Patient 1: In 2017, after a follow-up of 4 years, the patient presented with fever, lymphadenopathy, splenomegaly, and pancytopenia in the setting of hemophagocytic syndrome. The initial diagnosis was a relapse of lymphoma and the patient was treated with ibrutinib. His status worsened, and Leishmania DNA was detected by polymerase chain reaction (PCR) on the blood and bone marrow aspirates. Ibrutinib was stopped. Amphotericin B treatment induced a complete clinical remission and clearance of Leishmania DNA from the blood.Patient 2: In 2017, after a follow-up of 14 years, the patient presented with fever, lymphadenopathy, hepatosplenomegaly, pancytopenia with hemophagocytic syndrome, and an increase in the tumor skin lesions. A skin biopsy was taken from the face and the patient. A careful reexamination of the skin biopsy revealed the presence of Leishmania bodies. He was treated with 40 mg/kg liposomal amphotericin B leading to a regression of the clinical symptoms and negativation of the blood PCR.

CONCLUSIONS

This case study shows that VL may be a diagnostic challenge in patients with lymphoma. Reactivation or primary infection should be considered in the differential diagnosis. The purpose of this study is to remind clinicians to think of VL in patients with systemic symptoms that could be misdiagnosed as a progression of the underlying lymphoma.

preADMET analysis and clinical aspects of dogs treated with the Organotellurium compound RF07: A possible control for canine visceral leishmaniasis?

Tellurium compounds have been described as potential leishmanicides, bearing promising leishmanicidal and antimalarial effects. Therefore, the present study investigated the pharmacological potential of the organotellurane compound RF07 through preADMET parameters, such as absorption, distribution, metabolism and excretion. After studying the pharmacokinetic properties of RF07, studies were carried out on dogs naturally infected with visceral leishmaniasis after the administration of RF07, in order to assess pathophysiological parameters. Thus, dogs were divided into 4 groups with administration of daily intraperitoneal injections for 3 weeks (containing RF07 or placebo). During the trial, hematological parameters, renal and hepatic toxicity were evaluated. Serum urea, creatinine, alkaline phosphatase, transaminases (GOT and GPT), as well as hemogram results, were evaluated before the first administration and during the second and third weeks after the start of the treatment. In dogs with VL, RF07 improved liver damage, regulated GPT levels and significantly decreased leukocyte count, promoting its regularization. These phenomena occurred at the end of the third week of treatment. The administration of RF07 promoted a significant decrease in the average levels of GOT and GPT after the third week of treatment and did not significantly alter the hematological parameters. The application of RF07 in the treatment of visceral leishmaniasis suggests that it is an alternative to the disease, since the reversal of clinical signs in dogs with VL requires the use of 0.6 mg/kg.

Intracellular adenosine released from THP-1 differentiated human macrophages is involved in an autocrine control of Leishmania parasitic burden, mediated by adenosine A2A and A2B receptors

Leishmania infected macrophages have conditions to produce adenosine. Despite its known immunosuppressive effects, no studies have yet established whether adenosine alter Leishmania parasitic burden upon macrophage infection. This work aimed at investigating whether endogenous adenosine exerts an autocrine modulation of macrophage response towards Leishmania infection, identifying its origin and potential pharmacological targets for visceral leishmaniasis (VL), using THP-1 differentiated macrophages. Adenosine deaminase treatment of infected THP-1 cells reduced the parasitic burden (29.1 ± 2.2%, P < 0.05). Adenosine A_2A and A_2B receptor subtypes expression was confirmed by RT-qPCR and by immunocytochemistry and their blockade with selective adenosine A_2A and A_2B antagonists reduced the parasitic burden [14.5 ± 3.1% (P < 0.05) and 12.3 ± 3.1% (P < 0.05), respectively; and 24.9 ± 2.8% (P < 0.05), by the combination of the two antagonists)], suggesting that adenosine A₂ receptors are tonically activated in infected THP-1 differentiated macrophages. The tonic activation of adenosine A₂ receptors was dependent on the release of intracellular adenosine through equilibrative nucleoside transporters (ENT1/ENT2): NBTI or dipyridamole reduced (~25%) whereas, when ENTs were blocked, adenosine A₂ receptor antagonists failed to reduce and A₂ agonists increase parasitic burden. Effects of adenosine A₂ receptors antagonists and ENT1/2 inhibitor were prevented by L-NAME, indicating that nitric oxide production inhibition prevents adenosine from increasing parasitic burden. Results suggest that intracellular adenosine, released through ENTs, elicits an autocrine increase in parasitic burden in THP-1 macrophages, through adenosine A₂ receptors activation. These observations open the possibility to use well-established ENT inhibitors or adenosine A₂ receptor antagonists as new therapeutic approaches in VL.

In vivo experiments demonstrate the potent antileishmanial efficacy of repurposed suramin in visceral leishmaniasis

BACKGROUND

Treatment failure and resistance to the commonly used drugs remains a major obstacle for successful chemotherapy against visceral leishmaniasis (VL). Since the development of novel therapeutics involves exorbitant costs, the effectiveness of the currently available antitrypanosomatid drug suramin has been investigated as an antileishmanial, specifically for VL,in vitro and in animal model experiments.

METHODOLOGY/PRINCIPAL

Leishmania donovani promastigotes were treated with suramin and studies were performed to determine the extent and mode of cell mortality, cell cycle arrest and other in vitro parameters. In addition, L. donovani infected BALB/c mice were administered suramin and a host of immunological parameters determined to estimate the antileishmanial potency of the drug. Finally, isothermal titration calorimetry (ITC) and enzymatic assays were used to probe the interaction of the drug with one of its putative targets namely parasitic phosphoglycerate kinase (LmPGK).

FINDINGS

The in vitro studies revealed the potential efficacy of suramin against the Leishmania parasite. This observation was further substantiated in the in vivo murine model, which demonstrated that upon suramin administration, the Leishmania infected BALB/c mice were able to reduce the parasitic burden and also generate the host protective immunological responses. ITC and enzyme assays confirmed the binding and consequent inhibition of LmPGK due to the drug.

CONCLUSIONS/SIGNIFICANCE

All experiments affirmed the efficacy of suramin against L. donovani infection, which could possibly lead to its inclusion in the repertoire of drugs against VL.

Post kala-azar dermal leishmaniasis: A threat to elimination program

Leishmaniasis remains a public health concern around the world that primarily affects poor folks of the developing world spanning across 98 countries with mortality of 0.2 million to 0.4 million annually. Post kala-azar dermal leishmaniasis (PKDL) is the late skin manifestation of visceral leishmaniasis (VL). It has been reported that about 2.5% to 20% of patients recovered from VL develop PKDL having stilted macular or nodular lesions with parasites. In the Indian subcontinent (ISC), it manifests a few months after recovery from VL, though in Africa it can occur simultaneously with VL or a little later. New cases of PKDL are also observed without prior VL in the ISC. These individuals with PKDL represent an important but largely neglected reservoir of infection that perpetuates anthroponotic Leishmania donovani transmission in the ISC and can jeopardize the VL elimination program as these cases can infect the sand flies and spread the endemic. Therefore, it becomes imperative to eradicate PKDL as a part of the VL elimination program. With the limited treatment options besides little knowledge on PKDL, this review stands out in focusing on different aspects that should be dealt for sustained VL elimination.

Highly sensitive UPLC-MS/MS method for the quantification of paromomycin in human plasma

A highly sensitive method was developed to quantitate the antileishmanial agent paromomycin in human plasma, with a lower limit of quantification of 5 ng/mL. Separation was achieved using an isocratic ion-pair ultra-high performance liquid chromatographic (UPLC) method with a minimal concentration of heptafluorobutyric acid, which was coupled through an electrospray ionization interface to a triple quadrupole - linear ion trap mass spectrometer for detection. The method was validated over a linear calibration range of 5 to 1000 ng/mL (r²≥0.997) with inter-assay accuracies and precisions within the internationally accepted criteria. Volumes of 50 μL of human K₂EDTA plasma were processed by using a simple protein precipitation method with 40 μL 20 % trichloroacetic acid. A good performance was shown in terms of recovery (100 %), matrix effect (C.V. ≤ 12.0 %) and carry-over (≤17.5 % of the lower limit of quantitation). Paromomycin spiked to human plasma samples was stable for at least 24 h at room temperature, 6 h at 35 °C, and 104 days at -20 °C. Paromomycin adsorbs to glass containers at low concentrations, and therefore acidic conditions were used throughout the assay, in combination with polypropylene tubes and autosampler vials. The assay was successfully applied in a pharmacokinetic study in visceral leishmaniasis patients from Eastern Africa.

A Multi-Species Phenotypic Screening Assay for Leishmaniasis Drug Discovery Shows That Active Compounds Display a High Degree of Species-Specificity

High genetic and phenotypic variability between Leishmania species and strains within species make the development of broad-spectrum antileishmanial drugs challenging. Thus, screening panels consisting of several diverse Leishmania species can be useful in enabling compound prioritization based on their spectrum of activity. In this study, a robust and reproducible high content assay was developed, and 1280 small molecules were simultaneously screened against clinically relevant cutaneous and visceral species: L. amazonensis, L. braziliensis, and L. donovani. The assay is based on THP-1 macrophages infected with stationary phase promastigotes and posterior evaluation of both compound antileishmanial activity and host cell toxicity. The profile of compound activity was species-specific, and out of 51 active compounds, only 14 presented broad-spectrum activity against the three species, with activities ranging from 52% to 100%. Notably, the compounds CB1954, Clomipramine, Maprotiline, Protriptyline, and ML-9 presented pan-leishmanial activity, with efficacy greater than 70%. The results highlight the reduced number of compound classes with pan-leishmanial activity that might be available from diversity libraries, emphasizing the need to screen active compounds against a panel of species and strains. The assay reported here can be adapted to virtually any Leishmania species without the need for genetic modification of parasites, providing the basis for the discovery of broad spectrum anti-leishmanial agents.

Impact of clinically acquired miltefosine resistance by Leishmania infantum on mouse and sand fly infection

Objectives

This study evaluated the implications of clinically acquired miltefosine resistance (MIL-R) by assessing virulence in mice and sand flies to reveal the potential of MIL-R strains to circulate.

Methods

Experimental infections with the MIL-R clinical Leishmania infantum isolate MHOM/FR/2005/LEM5159, having a defect in the LiROS3 subunit of the MIL-transporter, and its syngeneic experimentally reconstituted MIL-S counterpart (LEM5159^LiROS3) were performed in BALB/c mice and Lutzomyia longipalpis and Phlebotomus perniciosus sand flies. In mice, the amastigote burdens in liver and spleen were compared microscopically using Giemsa smears and by bioluminescent imaging. During the sand fly infections, the percentage of infected flies, parasite load, colonization of the stomodeal valve and metacyclogenesis were evaluated. The stability of the MIL-R phenotype after sand fly and mouse passage was determined as well.

Results

The fitness of the MIL-R strain differed between the mouse and sand fly infection model. In mice, a clear fitness loss was observed compared to the LiROS3-reconstituted susceptible strain. This defect could be rescued by episomal reconstitution with a wildtype LiROS3 copy. However, this fitness loss was not apparent in the sand fly vector, resulting in metacyclogenesis and efficient colonization of the stomodeal valve. Resistance was stable after passage in both sand fly and mouse.

Conclusion

The natural MIL-R strain is significantly hampered in its ability to multiply and cause a typical visceral infection pattern in BALB/c mice. However, this LiROS3-deficient strain efficiently produced mature infections and metacyclic promastigotes in the sand fly vector highlighting the transmission potential of this particular MIL-R clinical Leishmania strain.

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A clinical MIL-R L. infantum strain displays a loss-of-fitness in the mammalian host.

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ROS3-deficiency is compatible with efficient transmission by two sand fly species.

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Resistance is stable after mouse and sand fly passage.

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Transmission of this clinical MIL-R strain is a risk for immunocompromised patients.