Cutaneous Leishmaniasis Research Articles

Optimization of the control strategy and research priorities to combat the resurgence of visceral leishmaniasis in China

Leishmaniasis is a zoonotic parasitic disease caused by Leishmania infection and transmitted by sandflies. There are three main forms of leishmaniasis, including cutaneous leishmaniasis, visceral leishmaniasis and mucocutaneous leishmaniasis. China is mainly endemic for visceral leishmaniasis, which is a class C notifiable infectious disease in the country. Following concerted efforts, the transmission of visceral leishmaniasis had been controlled in most endemic foci of China by the end of 1958, with a few cases reported in western China. Due to global climate changes and population mobility, resurgence of visceral leishmaniasis has recently occurred in historical endemic areas of central and western China, which is characterized by gradual expansion of endemic areas and remarkable rebounding epidemics. Hereby, we summarize the national and global epidemiology and control strategy of visceral leishmaniasis, propose 8 key research areas and 12 key research topics for visceral leishmaniasis control, and recommend the establishment of the joint prevention and control mechanism of "human-animals-vectors" and the working mechanism of animal prevention for human diseases based on the One Health approach, so as to combat the resurgence of visceral leishmaniasis in China.

Detection of Leishmania RNA Virus 2 (LRV2) among Clinical Isolates of Leishmania Major in Four Endemic Regions of Iran.

Leishmania RNA viruses (LRV) are double-stranded RNA viruses (dsRNA viruses) that play a role in the pathogenesis of Leishmania parasites. Cutaneous leishmaniasis (CL) is endemic in various parts of Iran. Our aimed was to investigate presence of LRV among the Leishmania major isolates in four endemic regions of Iran. In a cross-sectional study, we assessed the presence of LRV1 and LRV2 in 181 clinical isolates of L. major from four endemic cities in Iran using reverse transcription polymerase chain reaction (RT-PCR). After RNA extraction and cDNA synthesis, RT-PCR tests were conducted with LRV1 and LRV2 specific primers. Human beta-actin and kmp genes served as internal and external controls, respectively, and the Allele ID software was used to optimize melting curves. LRV2 was detected in 27.6% (50 out of 181) of L. major isolates, while no LRV1 was found. We did not observe a statistically significant difference in the presence of LRV2 based on age group, number, or location of lesions. This study confirms the presence of LRV2 in clinical isolates of L. major from endemic regions of Iran. Further researches with larger sample sizes is recommended to explore the association between LRV and clinical symptoms as well as treatment response.

HIF-α signaling regulates the macrophage inflammatory response during Leishmania major infection.

Cutaneous leishmaniasis (CL) contributes significantly to the global burden of neglected tropical diseases, with 12 million people currently infected with Leishmania parasites. CL encompasses a range of disease manifestations, from self-healing skin lesions to permanent disfigurations. Currently there is no vaccine available, and many patients are refractory to treatment, emphasizing the need for new therapeutic targets. Previous work demonstrated macrophage HIF-α-mediated lymphangiogenesis is necessary to achieve efficient wound resolution during murine L. major infection. Here, we investigate the role of macrophage HIF-α signaling independent of lymphangiogenesis. We sought to determine the relative contributions of the parasite and the host-mediated inflammation in the lesional microenvironment to myeloid HIF-α signaling. Because HIF-α activation can be detected in infected and bystander macrophages in leishmanial lesions, we hypothesize it is the host's inflammatory response and microenvironment, rather than the parasite, that triggers HIF-α activation. To address this, macrophages from mice with intact HIF-α signaling (LysM Cre ARNT f/+ ) or mice with deleted HIF-α signaling (LysM Cre ARNT f/f ) were subjected to RNASequencing after L. major infection and under pro-inflammatory stimulus. We report that L. major infection alone is enough to induce some minor HIF-α-dependent transcriptomic changes, while infection with L. major in combincation with pro-inflammatory stimuli induces numerous transcriptomic changes that are both dependent and independent of HIF-α signaling. Additionally, by coupling transcriptomic analysis with several pathway analyses, we found HIF-α suppresses pathways involved in protein translation during L. major infection in a pro-inflammatory environment. Together these findings show L. major induces a HIF-α-dependent transcriptomic program, but HIF-α only suppresses protein translation in a pro-inflammatory environment. Thus, this work indicates the host inflammatory response, rather than the parasite, largely contributes to myeloid HIF-α signaling during Leishmania infection.

Epidemiological Mapping of Cutaneous Leishmaniasis in Saudi Arabia: An Observational Descriptive Study

Cutaneous leishmaniasis (CL) is a parasitic disease that affects individuals worldwide. An epidemiological observational population–cohort study was conducted on the basis of comprehensive research on CL incidence in Saudi and non-Saudi residents. The Ministry of Health recorded the incidence of CL between January 2020 and December 2022. The chi-square test was used to analyze the data and determine CL incidence rates in age-specific incidence rates (ASIRs) and gender between Saudi and non-Saudi residents in Saudi Arabia. The study found that between 2020 and 2022, there were 2280 cases of CL in Saudi Arabia, with 1367 and 913 cases in men and women, respectively. Of Saudi nationals, 64.26% and 12.91% were male and female, respectively. The frequency of CL was higher (87.09%) among non-Saudi residents than among Saudi nationals, with a statistically significant difference (P = 0.001) between the two groups. The ASIRs for CL were higher in patients aged 15–45 years. This study revealed variations in CL incidence rates among the 13 administrative regions; Qassim, followed by Aseer, Ha’il, and Madinah, had higher rates than the other regions. These findings indicate the need for targeted interventions and public health strategies to reduce the burden on CL, particularly among non-Saudi residents.

A Systematic Assessment of Leishmania donovani Infection in Domestic and Wild Animal Reservoir Hosts of Zoonotic Visceral Leishmaniasis in India

Leishmaniasis is a neglected disease with a global spread that affects both domestic and wild animals in addition to people. Leishmania donovani is the suspected anthroponotic cause of visceral leishmaniasis (VL) in India, where it is an endemic disease. The reservoir hosts play a crucial role in the life cycle of the Leishmania parasite. The complicated connection between the pathogen, vector, and reservoir exhibits geographical and temporal diversity. Human-to-human and, to a lesser extent, human-to-animal transmission are the principal mechanisms for the maintenance of anthroponotic diseases. A number of animals were examined for the presence of Leishmania parasites and the findings were reviewed in order to examine the role of animal reservoirs in domestic transmission of cutaneous leishmaniasis in endemic regions of India. The analysis objective was to assess the research conducted on domestic animals’ propensity to spread L. donovani in endemic areas, with a particular emphasis on how proximity and animal density may impact the prevalence of human leishmaniasis. Species of the L. donovani complex have distinct enzootic, zoonotic, and anthroponotic life cycles that depend on the environment. The majority of Leishmania spp. are zoonotic, spreading from non-human mammals to humans. Many nations have leishmaniasis as an endemic disease, and the Indian subcontinent (ISC) has an estimated two to three lakh people who are at risk. This systematic review evaluates the gaps in our understanding of disease transmission that contradict conventional wisdom about the reservoir(s) of visceral leishmaniasis and efforts to manage it on the Indian subcontinent. Fundamental concerns in VL epidemiology and ecology will be clarified by a better understanding of L. donovani infection in domestic animals and its transfer to sandflies. A deliberate, systematic search was conducted on PubMed, Science Direct, and Google Scholar using keywords such as “Leishmania donovani”, “zoonotic visceral leishmaniasis”, and “wild animal reservoir for Leishmania donovani”. A total of 530 potentially relevant references were obtained from these databases, and 507 were not considered due to copy avoidance, irrelevant titles, research publications from nations other than India, or modified compositions. Among the remaining 23 investigations, 20 were rejected, and only 3 were included in the present study. Finally, three research papers with 867 goats, 161 cattle, 106 chickens, 26 sheep, three buffaloes, 406 dogs, and 309 rats were reported. Along with these data, studies across Asian and African countries that are considered VL-endemic areas have been discussed. According to the review, goats are the epidemic’s primary host and possible reservoir in several regions of India. In the endemic regions of the disease, some species of rodents, along with the canines, appear to be maintaining the L. donovani transmission cycle.

In Vivo Evaluation of Sepigel-Based Meglumine Antimoniate and Amphotericin B for Cutaneous Leishmaniasis Treatment.

Cutaneous leishmaniasis (CL) poses a significant public health concern in endemic regions due to its increasing prevalence and substantial impact on affected individuals. This disease is primarily caused by the Leishmania protozoa, which are transmitted through insect bites, and it manifests as a range of symptoms, from self-healing lesions to severe disfigurement. Current treatments, which often involve the parenteral administration of antimonials, face challenges such as poor compliance and adverse effects. This study investigates the efficacy of topical formulations containing meglumine antimoniate (MA) and amphotericin B (AmB), using Sepigel as an excipient, for treating CL. In the in vivo study, BALB/c mice infected with L. amazonensis developed lesions at the injection site five weeks post-infection. Subsequently, the mice were divided into eight groups: untreated mice, mice treated orally with miltefosine, mice treated intraperitoneally with MA, and mice treated topically with 15%, 22.5%, and 30% MA-Sepigel, as well as those treated with AmB-Sepigel. Treatments were applied daily for two weeks, and the results revealed a significant reduction in lesion size and parasite burden following topical application, particularly with the AmB-Sepigel formulations and 30% MA-Sepigel. Additionally, Sepigel-based treatments demonstrated improved patient compliance and reduced toxicity compared to systemic therapies. These findings underscore the potential of Sepigel-based formulations as a promising alternative for CL treatment. They offer enhanced efficacy and tolerability, while reducing the systemic toxicity associated with conventional therapies.

Letter in response to "Many faces of cutaneous leishmaniasis".

Letter in response to "Many faces of cutaneous leishmaniasis".

Effect of cutaneous leishmaniasis on hematological and immunological parameters in children/Iraq

Effect of cutaneous leishmaniasis on hematological and immunological parameters in children/Iraq

Demographic characteristics and clinical features of patients presenting with different forms of cutaneous leishmaniasis, in Lay Gayint, Northern Ethiopia.

Cutaneous leishmaniasis (CL) is a neglected tropical disease caused by Leishmania parasites, that can cause long-term chronic disabilities. The clinical presentation of CL varies in both type and severity. CL presents as three main clinical forms: localised lesions (localised cutaneous leishmaniasis, LCL); mucocutaneous leishmaniasis (MCL) that affects the mucosa of the nose or the mouth; or as disseminated not ulcerating nodules (diffuse cutaneous leishmaniasis, DCL). Here we recruited a cohort of CL patients in a newly established leishmaniasis treatment centre (LTC) in Lay Gayint, Northwest Ethiopia, and collected detailed demographic and clinical data. The results of our study show that more males than females present to the LTC to seek diagnosis and treatment. 70.2% of CL patients presented with LCL and 20.8% with MCL. A small number of patients presented with DCL, recidivans CL (a rare form of CL where new lesions appear on the edges of CL scars) or with a combination of different clinical presentations. The duration of illness varied from 1 month to 180 months. Over a third of CL patients had additional suspected CL cases in their household. Despite the majority of CL patients having heard about CL, only a minority knew about its transmission or that it could be treated. Most CL patients lived in areas where environmental factors known to be associated with the transmission of CL were present. This work highlights that CL is an important public health problem in Lay Gayint and emphasises the urgent need for more CL awareness campaigns, better health education and better disease management practices.

Semen Cannabis and Oleum Hyperici: Antileishmanial activity against Leishmania tropica promastigotes and intracellular amastigotes

The exploration of alternative agents and novel drug candidates for the effective treatment of cutaneous leishmaniasis has garnered significant attention, driven by the high cost, toxic effects, and the emergence of drug resistance associated with current therapeutic options. Plant extracts derived from Semen Cannabis, the seeds of the Cannabis sativa L. (hemp) plant, and Oleum Hyperici, the oily macerate of Hypericum perforatum L. (St. John's Wort) plant, were prepared by using solvents of varying polarity (n-hexane, chloroform, ethanol, and 60% aqueous ethanol). The primary objective of this study was to research in vitro and ex vivo antileishmanial efficacy of Semen Cannabis and Oleum Hyperici plant extracts against Leishmania tropica promastigotes and intracellular amastigotes. The efficacy of plant extracts against promastigotes were assessed using the cell counting by hemocytometer and the CellTiter-Glo assay. Additionally, their impact on infected THP-1 macrophages and the quantity of intracelluler amastigotes were investigated. Cytotoxicity was evaluated in THP-1 macrophages. Among the tested plant extracts, chloroform extract of Oleum Hyperici demonstrated significant antileishmanial activity against promastigotes (SI: 12.6) and intracellular amastigotes (SI: 16.8) of L. tropica without inducing cytotoxic effects and hold promise for further investigation as potential antileishmanial agents.

Use of topical rSm29 in combination with intravenous meglumine antimoniate in the treatment of cutaneous leishmaniasis: A randomized controlled trial

BackgroundCutaneous leishmaniasis (CL) caused by Leishmania (Viannia) braziliensis is associated with an inflammatory response. Granzyme (GzmB) and IL-1β play a key role in the pathology. Meglumine antimoniate (MA) is the first-choice drug for the treatment of CL, but therapy failure is observed in up to 50% of the cases. The protein, rSm29 of Schistosoma mansoni, down-modulates pro-inflammatory cytokine production. We evaluate if the combination of topical rSm29 plus MA increases the cure rate of CL. MethodsIn this randomized clinical trial, 91 CL patients were allocated in 3 groups. All cases received MA (20 mg/kg/weight) for 20 days. Group 1 used topical rSm29 (10 µg), group 2 a placebo topically applied, and group 3 received only MA. ResultsThe cure rate on day 90 was 71% in subjects treated with rSm29 plus MA, and 43% in patients who received MA plus placebo or MA alone (P < 0.05). There was a decrease in GzmB and an increase in IFN-γ (P < 0.05) in supernatants of skin biopsies of the lesions obtained on D7 of therapy (P < 0.05) in patients who received rSm29. ConclusionrSm29 associated with MA reduces GzmB levels, is more effective than MA alone, and decreases CL healing time. Clinical trials registrationClinicalTrial.gov under NCT06000514.

First detection of Leishmania major in dogs living in an endemic area of zoonotic cutaneous leishmaniasis in Tunisia

BackgroundDogs are considered the main domestic animals that may be a reservoir for Leishmania infantum, the agent of zoonotic visceral leishmaniasis (ZVL) in several countries of the world. The dog may host other Leishmania species, but its epidemiological role in the maintenance and spreading of these parasites is not completely elucidated. Zoonotic cutaneous leishmaniasis (ZCL), caused by Leishmania major, affects thousands of people every year and is particularly diffused in many countries of North Africa and Middle East Asia. In ZCL endemic countries, few reports of L. major-positive dogs have been reported, probably because most human cases occur in poor rural areas where the social role of the dog and its medical management is not well considered. The aim of the present study is to better understand the possible involvement of domestic dogs in the epidemiology of ZCL.MethodsOur research focused on a well-established endemic focus of ZCL, in the area of Echrarda, Kairouan Governorate, central Tunisia. A total of 51 dogs with no or mild clinical signs of vector borne diseases were selected in small villages where human cases of ZCL are yearly present. All dogs were sampled for the Leishmania spp. diagnosis, by using the following procedures: blood sample for serology and buffy coat quantitative polymerase chain reaction (qPCR), popliteal fine needle aspiration, and cutaneous biopsy punch for lymph node and skin qPCR.ResultsThe results demonstrated a high percentage (21.6%) of dogs positive at least at one or more test; the most sensitive technique was the lymph node qPCR that detected 8/11 positive dogs. Nine, out of the eleven positive dogs, resulted as infected by Leishmania infantum; ITS1-PCR-sequencing allowed Leishmania major identification in the remaining two cases, both from the popliteal lymph node samples, which can suggest a possible visceral spread of a cutaneous Leishmania species in the dog. Interestingly, one of the two L. major-positive dogs was living in the same house where 6-year-old children showed cutaneous lesions referred to as ZCL.ConclusionsTo our knowledge, this is the first report of L. major-positive dogs in Tunisia, the epidemiological role of which remains under investigation.Graphical

Enhanced translational activity is linked to lymphatic endothelial cell activation in cutaneous leishmaniasis.

Cutaneous leishmaniasis (CL) is a significant public health problem leading to permanently disfiguring skin lesions caused by Leishmania parasites. Lesion severity stems from an excessive host inflammatory response that prevents healing. Here, we characterized the transcriptional and translational responses of lymphatic endothelial cells (LECs) during murine CL using historical single-cell RNA sequencing data combined with flow cytometry and in vivo puromycin incorporation to assess translational activity. We identified upregulation of antigen presentation pathways including MHC-I, MHC-II, and immunoproteasome transcripts in dermal LECs from Leishmania major -infected mice compared to naive controls. LECs also exhibited increased expression of guanylate binding proteins and interferon-inducible genes, indicative of immune activation. Moreover, our findings demonstrate that LECs in leishmanial lesions displayed heightened translational activity relative to LECs from uninflamed ears, and LEC translational activity was highest in activated LECs. Furthermore, LEC translational activity exceeded that of other cell types within the lesion microenvironment. Validating the transcriptomic data, LECs in lesions expressed elevated MHC-II and programmed death-ligand 1 (PDL-1), supporting their potential role in antigen presentation. Functional assays using DQ-OVA confirmed that LECs from leishmanial lesions efficiently uptake and process antigens, highlighting their capability as antigen presenting cells in the inflamed dermal microenvironment. Overall, our study reveals the activation status of LECs in leishmanial lesions, shedding light on their potential role in shaping local immunity and inflammation in a variety of skin diseases.

The Role of Melatonin in the Inflammatory Process in Patients with Hyperglycemia and Leishmania Infection.

Type 2 diabetes mellitus is a metabolic disorder that causes chronic high blood sugar levels, and diabetic patients are more susceptible to infections. American cutaneous leishmaniasis is an infectious disease caused by a parasite that affects the skin and mucous membranes, leading to one or multiple ulcerative lesions. Chronic inflammation and functional changes in various organs and systems, including the immune system, are the primary causes of both diseases. Melatonin, an essential immunomodulatory, antioxidant, and neuroprotective agent, can benefit many immunological processes and infectious diseases, including leishmaniasis. Although, limited reports are available on diabetic patients with leishmaniasis. The literature suggests that melatonin may play a promising role in inflammatory disorders. This study was designed to assess melatonin levels and inflammatory mediators in diabetic patients affected by leishmaniasis. Blood samples from 25 individuals were analyzed and divided into four groups: a control group (without any diseases), a Leishmania-positive group, patients with type 2 diabetes mellitus, and patients with a combination of both diseases. This study measured the serum levels of melatonin through ELISA, while IL-4 and TNF-α were measured using flow cytometry, and C-reactive protein was measured through turbidimetry. This study found that patients with leishmaniasis significantly increased TNF-α and decreased melatonin levels. However, the group of diabetic patients with leishmaniasis showed higher melatonin levels than the control group. These observations suggest that TNF-α may influence melatonin production in patients with American cutaneous leishmaniasis, potentially contributing to the inflammatory characteristics of both diseases.

Safety and reactogenicity of a controlled human infection model of sand fly-transmitted cutaneous leishmaniasis.

The leishmaniases are globally important parasitic diseases for which no human vaccines are currently available. To facilitate vaccine development, we conducted an open-label observational study to establish a controlled human infection model (CHIM) of sand fly-transmitted cutaneous leishmaniasis (CL) caused by Leishmania major. Between 24 January and 12 August 2022, we exposed 14 participants to L. major-infected Phlebotomus duboscqi. The primary objective was to demonstrate effectiveness of lesion development (take rate) and safety (absence of CL lesion at 12 months). Secondary and exploratory objectives included rate of lesion development, parasite load and analysis of local immune responses by immunohistology and spatial transcriptomics. Lesion development was terminated by therapeutic biopsy (between days 14 and 42 after bite) in ten participants with clinically compatible lesions, one of which was not confirmed by parasite detection. We estimated an overall take rate for CL development of 64% (9/14). Two of ten participants had one and one of ten participants had two lesion recurrences 4-8 months after biopsy that were treated successfully with cryotherapy. No severe or serious adverse events were recorded, but as expected, scarring due to a combination of CL and the biopsy procedure was evident. All participants were lesion free at >12-month follow-up. We provide the first comprehensive map of immune cell distribution and cytokine/chemokine expression in human CL lesions, revealing discrete immune niches. This CHIM offers opportunities for vaccine candidate selection based on human efficacy data and for a greater understanding of immune-mediated pathology. ClinicalTrials.gov identifier: NCT04512742 .

Knowledge, attitude, prevention practice and lived experience towards cutaneous leishmaniasis and associated factors among residents of Kutaber district, Northeast Ethiopia, 2022: A mixed method study.

Cutaneous leishmaniasis is a widespread parasitic infection in Ethiopia. Few studies have been conducted on knowledge, attitudes, and prevention practice related to cutaneous leishmaniasis, and the existing studies have been mainly without qualitative support. This study aimed to assess the knowledge, attitude, prevention practice and lived experience towards cutaneous leishmaniasis and associated factors among residents of the Kutaber district, Northeast Ethiopia. A convergent parallel mixed method was conducted among 636 residents (for quantitative) and 20 in-depth interview participants (for qualitative) of the Kutaber district from July 1 to August 15, 2022. Quantitative data were entered into Epi-Data version 4.6 and exported to SPSS version 25 for cleaning and analysis. ATLAS.ti software version 8.0 was used for the analysis of qualitative data. The survey respondents in Kutaber district showed good knowledge (47.5%), a positive attitude towards (54.1%) and a good prevention practice (35.3%) regarding cutaneous leishmaniasis. Residents who were unable to read and write [AOR = 0.15] had lower odds to have good knowledge about cutaneous leishmaniasis. Residents aged >54.5 years [AOR = 0.33] had lower odds to have a positive attitude towards cutaneous leishmaniasis. Males [AOR = 1.76] had a good prevention practice towards cutaneous leishmaniasis. Five main study themes were formed following the qualitative analysis of the data. Residents of Kutaber district have a poor overall knowledge and prevention practice towards cutaneous leishmaniasis, despite having a positive attitude. The educational status of residents and years of residence were factors significantly associated with knowledge about cutaneous leishmaniasis. Age and years of residence were factors significantly associated with attitude towards cutaneous leishmaniasis. Gender, age, and household wealth were factors significantly associated with prevention practice towards cutaneous leishmaniasis. Cutaneous leishmaniasis in Kutaber is a true health problem.

The Therapeutic Effect of Shirvan Herbal Ointment on Human Cutaneous Leishmaniasis Compared with Glucantime.

Cutaneous leishmaniasis (CL) infection is caused by the Leishmania major (L. major) parasite and affects 1.5 to 2 million people worldwide each year. Although research into vaccines and antiparasitic drugs has been somewhat successful, their adverse effects include high toxicity, prolonged regeneration, and scarring. This has highlighted the importance of research to replace natural products with antibacterial and antioxidant properties, such as vegetable extracts and oils. Since, the anti-leishmaniasis effect of each of the components of Shirvan herbal ointment (aloe vera, Brazembel, Nigella sativa, propolis, lavender, and olive oil) has been separately studied and confirmed, it seems that the combination of these components can have an increasing anti-leishmanial effect to treat CL. Therefore, this study investigated the therapeutic impact of Shirvan herbal ointment on Iranian patients with leishmaniasis in comparison with glucantime (meglumine). Sixty patients with leishmaniasis were divided into the control and test groups. The control and test groups received intralesional glucantime and Shirvan herbal cream (two times daily), respectively. The size mean of the lesion was 51.5 ± 32.5 before and 11.11 ± 16.28 after treatment in the control group and 50.8 ± 31.2 before and 0.0 ± 0.0 after treatment in the test group. In addition, the period mean of treatment was 43.9 ± 14.4 days and 30.5 ± 7.4 days in the control and test groups, respectively. There was a significant difference in lesion size between the two groups after treatment. Data suggested that Shirvan herbal ointment can be an alternative drug in the treatment of human CL.

The Interaction of Zinc as an Essential Trace Element with Leishmania Parasites: A Systematic Review.

The trace element of zinc (Zn) has shown great effectiveness in control of leishmaniasis infection. Hence, the present study conducted a systematic review of in vitro and in vivo studies evaluating the zinc effect in the treatment or prevention of leishmaniasis. A systematic literature search was performed of all articles published in PubMed, SciELO, ScienceDirect, Scopus, Google Scholar, and Web of Science databases (1997-2023). The search terms were "zinc" OR "cutaneous leishmaniasis (CL)" OR "visceral leishmaniasis (VL)". Initial search yielded 89 citations, and 59 subjects were included. Data showed the zinc serum level in CL patients was lower than controls. Also, in vitro studies of zinc were more effective against L. tropica and L. major promastigotes compared to the amastigotes. Moreover, in vivo studies did not show destructive effects of zinc on the mammalian cell viability like macrophages. Furthermore, zinc depletion by specific chelators affected L. donovani survival and growth through promoting apoptosis and reactive oxygen species-dependent mechanisms. The serum level determination of zinc could be useful for estimating the leishmaniasis pathophysiology. Environmentally or genetically determined increases in zinc levels might augment resístanse to CL. In contrast, zinc depletion using a zinc-specific chelator could be effective treatment of VL in endemic areas.

In Vitro Evaluation of the Combinatorial Effect of Naringenin and Miltefosine against Leishmania amazonensis.

Leishmania amazonensis causes a clinical form called diffuse cutaneous leishmaniasis (DCL) with challenges to treatment, like low efficiency and drug toxicity. Therefore, it is necessary to investigate new therapies using less toxic leishmanicidal compounds, such as flavonoids like naringenin, and their combination with conventional drugs, such as miltefosine. Antileishmanial dose/response activity, isobologram, calculation of dose reduction index (DRI), and fractional inhibitory concentration index (FICI) tests were performed on in vitro assays using reference promastigote forms of L. amazonensis (IFLA/BR/67/PH8) to assess the combinatorial effect between naringenin and miltefosine. The in vitro results of isobologram, DRI, and FICI calculations showed that the combination of the compounds had an additive effect and was able to reduce the half maximal inhibitory concentration (IC50) of miltefosine in the promastigote forms of the parasite compared to the treatment of the drug alone. This study demonstrated in vitro the viability of a combination action of the flavonoid with the treatment with miltefosine, opening space for further investigations on the association of natural compounds with the drugs used for the treatment of L. amazonensis.

Microemulsions strongly promoted the activity of α-bisabolol against different Leishmania species and its skin permeation

This study aimed to develop microemulsions (MEs) containing α-bisabolol for the topical treatment of cutaneous leishmaniasis (CL). Initially, pseudoternary phase diagrams were developed using α-bisabolol as the oil phase, Eumulgin® CO 40 as the surfactant, Polymol® HE as the co-surfactant, and distilled water as the aqueous phase. Two transparent liquid systems (TLS) containing 5% of α-bisabolol were selected and characterized (F5E25 and F5EP25). Next, skin permeation and retention assays were performed using Franz cells. The interaction of the formulation with the stratum corneum (SC) was evaluated using the FTIR technique. The cytotoxicity was evaluated in murine peritoneal macrophages. Finally, the antileishmanial activity of microemulsions was determined in promastigotes and amastigotes of L. amazonensis (strain MHOM/BR/77/LTB 0016). As a result, the selected formulations showed isotropy, nanometric size (below 25 nm), Newtonian behavior and pH ranging from 6.5 to 6.9. The MEs achieved a 2.5-fold increase in the flux and skin-permeated amount of α-bisabolol. ATR-FTIR results showed that microemulsions promoted fluidization and extraction of lipids and proteins of the stratum corneum, increasing the diffusion coefficient and partition coefficient of the drug in the skin. Additionally, F5E25 and F5EP25 showed higher activity against promastigotes (IC50 13.27 and 18.29, respectively) compared to unencapsulated α-bisabolol (IC50 53.8). Furthermore, F5E25 and F5EP25 also showed antileishmanial activity against intracellular amastigotes of L. amazonensis, with IC50 50 times lower than free α-bisabolol and high selectivity index (up to 15). Therefore, the systems obtained are favorable to topical administration, with significant antileishmanial activity against L. amazonensis promastigotes and amastigotes, being a promising system for future in vivo trials.