The potential therapeutic role of PTR1 gene in non-healing anthroponotic cutaneous leishmaniasis due to Leishmania tropica

BACKGROUND

Drug resistance is a common phenomenon frequently observed in countries where leishmaniasis is endemic. Due to the production of the pteridine reductase enzyme (PTR1), drugs lose their efficacy, and consequently, the patient becomes unresponsive to treatment. This study aimed to compare the in vitro effect of meglumine antimoniate (MA) on non- healing Leishmania tropica isolates and on MA transfected non-healing one to PTR1.

METHODS

Two non-healing and one healing isolates of L. tropica were collected from patients who received two courses or one cycle of intralesional MA along with biweekly liquid nitrogen cryotherapy or systemic treatment alone, respectively. After confirmation of L. tropica isolates by polymerase chain reaction (PCR), the recombinant plasmid pcDNA-rPTR (antisense) was transfected via electroporation and cultured on M199. Isolates in form of promastigotes were treated with different concentrations of MA and read using an enzyme-linked immunosorbent assay (ELISA) reader and the half inhibitory concentration (IC50 ) value was calculated. The amastigotes were grown in mouse macrophages and were similarly treated with various concentrations of MA. The culture glass slides were stained, and the mean number of intramacrophage amastigotes and infected macrophages were assessed in triplicate for both stages.

RESULTS

All three transfected isolates displayed a reduction in optical density compared with the promastigotes in respective isolates, although there was no significant difference between non-healing and healing isolates. In contrast, in the clinical form (amastigotes), there was a significant difference between non-healing and healing isolates (p < 0.05).

CONCLUSION

The results indicated that the PTR1 gene reduced the efficacy of the drug, and its inhibition by antisense and could improve the treatment of non-healing cases. These findings have future implications in the prophylactic and therapeutic modality of non- healing Leishmania isolates to drug.

A long-lasting emerging epidemic of anthroponotic cutaneous leishmaniasis in southeastern Iran: population movement and peri-urban settlements as a major risk factor

Background

Epidemics of cutaneous leishmaniasis (CL) are occurring more frequently and spreading faster and farther than before in many areas of the world. The present study aimed to assess a long-lasting emerging epidemic (2005–2019) of 5532 cases with anthroponotic CL (ACL) in peri-urban areas of Kerman city in southeastern Iran.

Methods

This descriptive-analytical study was carried out for 15 years in Kerman province, southeastern Iran. The data were passively obtained through the health surveillance system and the Kerman Leishmaniasis Research Center. Every subject was diagnosed using direct smear microscopy. The representative causative agent was further examined by ITS1-PCR, PCR-RFLP, 7SL RNA gene sequencing and phylogenetic analyses. For each subject, a case report form designating demographic and clinical data was recorded.

Results

A different pattern of ACL incidence was found in peri-urban areas compared to that in the city of Kerman. The incidence rate of ACL cases has significantly increased (P < 0.001) from 2005 to 2016 in new settlements with a gradual decline after that. The overall average risk of contracting the disease was 7.6 times higher in peri-urban areas compared to Kerman city, an old endemic focus. All isolates consisting of six variants were confirmed to be Leishmania tropica. The overall pattern of the ACL infection indicates that the etiological agent of ACL is propagated and transmitted by the bite of female Phlebotomus sergenti sandflies from person to person from dissimilar clones as reflected by the complexity of the migrants’ backgrounds in the province.

Conclusions

The movement of populations and establishment of new settlements in peri-urban areas close to endemic areas are major risk factors for and are directly linked to CL. The underlying factors of this emerging ACL epidemic caused by L. tropica were disasters and droughts, among others. A robust commitment to a multilateral approach is crucial to make improvements in this area. This will require decisive coordinated actions through all governmental factions and non-governmental organizations. Furthermore, active and passive case detection strategies, early diagnosis, and effective treatment could help control the disease.

The immunity of the recombinant prokaryotic and eukaryotic subunit vaccines against cutaneous leishmaniasis

Leishmaniasis counts as one of the most neglected tropical diseases. Despite the amount of research perceived in this field, no fully effective and approved vaccine against this disease is yet available in humans. In this study, LACK and KMP11 antigens were constructed simultaneously by recombinant methods in prokaryotic and eukaryotic expression systems and were compared and assessed along with the CpG adjuvant in BALB/c mice. In the prokaryotic method, LACK and KMP11 protein gene sequences were synthesized in pET28a-TEV vector. In order to extract these two proteins after expression, His-tag and S-tag sequences were added to the constructs, respectively for LACK and KMP11. The pET28a-TEV-LACK/KMP11 construct was transformed into Escherichia coli, and the inserts were verified by Colony PCR. Pure proteins were verified by western blot, and groups of BALB/c mice were injected with the created prokaryotic recombinant proteins along with an ODN CpG adjuvant. In the eukaryotic method, antigen sequences were constructed in the pLEXSY-neo 2.1 vector, E.coli Top10 strain was cloned in the bacteria, and after being linearized were transfected into Leishmania tarentolae genome. After recombinant strains were selected, they were verified by molecular methods. After the extraction and purification of the protein using the method above, groups of mice were injected with the recombinant antigens and ODN CpG adjuvant. Eukaryotic subunit vaccines showed more effective immunization compared with prokaryotic vaccines and caused an immune system shift towards Th1 and protection. Protein expression in L. tarentolae by the constructs created in this host contains Post-Translational Modifications. The constructed protein will be significantly similar to eukaryotic proteins, considering that they are identical epitopes. More comprehensive studies aiming to improve the effectiveness of this vaccine are being conducted to improve immune profiles and immunological memory stimulation in future designs.

Major risk factors and histopathological profile of treatment failure, relapse and chronic patients with anthroponotic cutaneous leishmaniasis: A prospective case-control study on treatment outcome and their medical importance

Over the last years, there has been a remarkable increase in the number of unresponsive patients with anthroponotic cutaneous leishmaniasis (ACL) reported worldwide. The primary objective of this study was to explore the role of demographic, clinical and environmental risk related-factors in the development of treatment failure, relapse and chronic cases compared to responsive patients with ACL. Moreover, molecular, histopathological and immunohistochemical (IHC) findings between these forms were explored. This work was undertaken as a prospective and case-control study in southeastern Iran. Culture media and nested PCR were used to identify the causative agent. Univariate multinomial and multiple multinomial logistic regression models and the backward elimination stepwise method were applied to analyze the data. A P<0.05 was defined as significant. Also, for different groups, skin punch biopsies were used to study the histopathological and immunohistochemical (IHC) profile. All samples showed that L. tropica was the only etiological agent in all unresponsive and responsive patients with ACL. Data analysis represented that 8 major risk factors including nationality, age groups, occupation, marital status, history of chronic diseases, duration of the lesion, the lesion on face and presence of domestic animals in the house were significantly associated with the induction of unresponsive forms. The histopathological and immunohistochemical findings were different from one form to another. The present findings clearly demonstrated a positive relation between ACL and distinct demographic, clinical and environmental risk determinants. Knowledge of the main risk factors for ACL infection is crucial in improving clinical and public health strategies and monitor such perplexing factors.

Negligible data are present related to anthroponotic cutaneous leishmaniasis (ACL) treatment outcome and resultant unresponsiveness risk determinants. The role of demographic, clinical, and environmental risk associated-factors in the development of treatment failure, relapse, and chronic forms of ACL has not been studied. We carried out a case-control study for a period of 4 years (2015–2019) using culture media and nested PCR to identify the causative agent. Afterward, we analyzed the data by univariate multinomial and multiple multinomial logistic regression models and the backward elimination stepwise method. Also, we examined skin punch biopsies to study the histopathological and immunohistochemical (IHC) profile for different comparative groups. The findings identified 8 major risk factors were significantly associated with the creation of unresponsive forms. Clinical practitioners and health surveillance systems should be aware of and monitor such perplexing factors. Awareness of the major determinants for unresponsiveness to the treatment of ACL is critical to improving clinical strategies and public health measures. These multidisciplinary approaches need to address specific barriers that directly affect the treatment outcome.

Partridge and embryonated partridge egg as new preclinical models for candidiasis

Candida albicans (C. albicans) is the most common cause of candidiasis in humans and animals. This study was established to a new experimental infection model for systemic candidiasis using partridge and embryonated partridge egg. First, we tested the induction of systemic candidiasis in partridge and embryonated partridge egg. Finally, interaction between virulence factors of C. albicans and Bcl-2 family members was predicted. We observed that embryonic infection causes a decrease in survival time and at later embryonic days (11–12th), embryos showed lesions. Morphometric analysis of the extra-embryonic membrane (EEM) vasculature showed that vascular apoptotic effect of C. albicans was revealed by a significant reduction in capillary area. In immunohistochemistry assay, low expression of Bcl-2 and increased expression of Bax confirmed apoptosis. The gene expression of Bax and Bcl-2 was also altered in fungi-exposed EEM. Ourin silico simulation has shown an accurate interaction between aspartic proteinase, polyamine oxidase, Bcl-2 and BAX. We observed that the disease was associated with adverse consequences, which were similar to human candidiasis. Acquired results support the idea that partridge and embryonated partridge egg can be utilized as appropriate preclinical models to investigate the pathological effects of candidiasis.

The potential role and apoptotic profile of three medicinal plant extracts on Leishmania tropica by MTT assay, macrophage model and flow cytometry analysis

Introduction

Treatment of leishmaniasis with conventional synthetic drugs is a major global challenge. This study was designed to explore the leishmanicidal activity and apoptotic profile of three leaf extracts on Leishmania tropica stages.

Methods

The plants of Quercus velutina, Calotropis procera and Nicotiana tabacum were gathered from Anbarabbad county, in the southeastern part of Kerman province and extracted by maceration method using methanol alcohol. Various concentrations of the extracts (1, 10, 100 and 1000 μg/mL) were used against L. tropica stages to evaluate the inhibitory effect by colorimetric assay, macrophage model and flow cytometry. The MTT assay was conducted to determine the IC₅₀ and CC₅₀ values in promastigotes and J774-A1 macrophages, respectively. For intra-macrophage amastigotes, the leishmanicidal activity was evaluated by calculating the mean number of amastigotes in each macrophage and also IC₅₀ values. The promastigote or amastigote stages with no drug and complete medium without organisms were considered as positive and negative controls, respectively. Meglumine antimoniate (Glucantime) was also used as standard drug. Also, annexin V was used to assess the apoptotic profile. All treatment settings were incubated for a standard time of 72 h in triplicates. Data were analyzed by t-test and ANOVA.

Results

The findings showed that all plant extracts inhibited the proliferation rate of promastigotes and amastigotes (P ˂ 0.001); especially, Q. velutina represented the lowest IC₅₀ in both stages. Besides, Q. velutina showed the least number of amastigotes in each macrophage compared to the other groups (4.5 μg/mL). The percentage of parasitic apoptosis at 1000 μg/mL of Q. velutina, C. procera, N. tabacum and Glucantime® were 37.4, 18.6, 8.5 and 52.4, respectively. Amastigotes (clinical stage) were significantly more susceptible to extracts and also Glucantime® than promastigotes (P < 0.001).

Conclusions

This study revealed that all three extracts of Q. velutina, C. procera and N. tabacum exhibited an effective antileishmanial activity and induced apoptosis against the L. tropica promastigotes. Further investigations are essential to isolate and analyze the chemical compositions and their biological properties.

New foci of zoonotic cutaneous leishmaniosis due to Leishmania major in the northeastern Iran cities of Sabzevar and Neghaab

Cutaneous leishmaniosis (CL) is a major public health challenge in Iran. Overall, 18 provinces out of 31 of the country's provinces are in the endemic areas. The objective of the present study was to determine the presence of CL species in Sabzevar and Neghaab cities, Khorasan Razavi province, northeastern Iran. Overall, 280 samples were taken from suspected individuals referred to Sabzevar's and Neghaab's health centers during 2014-2016. Smear preparation, case detection and further identification by partial amplification of 7SL RNA and high-resolution melting curve analysis were done for all samples, followed by randomly polymerase chain reaction (PCR)-sequencing confirmation. Based on findings, the most infection rate was found in males with the age groups of 20-30 in both districts. All samples were characterized as Leishmania major, except one isolate in Neghaab closely related to Leishmania tropica. Various risk factors play roles in creating new foci of zoonotic CL (ZCL) caused by L. major in Sabzevar and Neghaab in northeastern Iran. Reports of the prevalence of CL in new foci make serious concerns about the incidence of cases and expansion of disease to the neighboring areas. Further measures are essential to control the disease in the regions.

Linguatulosis in small ruminants in southeastern Iran: Epidemiological, histopathological and phylogenetic findings and its public health importance

Linguatulosis, as a zoonotic disease, can infect most ruminants and cause accidental infections in humans. The objective of this study was to explore the epidemiological, histopathological and phylogenetic profiles of Linguatula serrata infection in sheep and goats and its public health importance during 2015-2018. Mesenteric lymph nodes (MLNs) and liver tissue of goats and sheep were selected randomly in Kerman slaughterhouse. Nymphal samples were used for DNA extraction, amplification and subsequently phylogenetic analysis using 18s rRNA and cytochrome C oxidase subunit 1 (cox1). Overall, of 828 examined livestock, 179 (42.4%) goats and 71 (17.5%) sheep were found to be infected with the nymphal stage of L. serrata. A significant difference was observed between linguatulosis and age. In the histopathological assessment, longitudinal and transverse sections of L. serrata nymphs were observed within the cyst-like spaces surrounded by a wall of fine fibrosis and compact lymphocytes. Moreover, comparing with the L. serrata reference sequences, we found only a single nucleotide change in our goat haplotype in 18s genetic region; while much nucleotide variations were observed in cox1 gene sequences. The results of the present study showed a high infection rate among goats and sheep in southeastern Iran. A better understanding of the disease could be achieved when the parasite species, their molecular characterization and the extent of infection in the area are determined. It is fundamental to select a comprehensive control program in order to take proper preventive and therapeutic measures against the infection.

The importance of T cell-derived cytokines in post-kala-azar dermal leishmaniasis

Infection with the same species of Leishmania (L)donovani causes different manifestations including visceral leishmaniasis (VL) and post kala-azar dermal leishmaniasis (PKDL), indicating that the host-related immunological parameters perform a decisive role in the pathogenesis of diseases. As PKDL is a reservoir of the parasite, a better understanding of the host immune responses is necessary to restrict the L. donovani transmission. The proper local production of Th1 cell-related cytokines (including IFN-γ, TNF-α and IL-12), Th17 cell-derived cytokines (such as IL-17A, IL-17F and IL-22), and CD8⁺ cytotoxic T lymphocyte (CTL)-derived IFN-γ are protective against PKDL. However, dominant production of regulatory CD4⁺ T cell-derived cytokines (such as IL-10 and TGF-β), Th2 cell-derived cytokines (such as IL-4/IL-13), M2 macrophage-derived cytokines (such as IL-4 and IL-10), keratinocyte-derived IL-10, regulatory CD8⁺ T cell-derived IL-10, and dendritic cell-derived IL-10, IL-27 and IL-21 can contribute to the parasite persistence and PKDL development. Understanding of the T cell-related cytokine network within PKDL lesions gives rise to novel insights concerning the role of each cytokine in the protection or susceptibility to disease. Manipulation of the cytokine network can be considered as an interesting immunotherapeutic strategy for the treatment of L. donovani-mediated PKDL.

Evaluation of a new live recombinant vaccine against cutaneous leishmaniasis in BALB/c mice

Background

Leishmaniasis is a serious health problem in some parts of the world. In spite of the many known leishmaniasis control measures, the disease has continued to increase in endemic areas, and no effective vaccine has been discovered.

Methods

In this study, Leishmania tarentulae was used as a living factory for the production of two LACK and KMP11 immunogenic antigens in the mice body, and safety profiles were investigated. The sequences of the KMP11 and LACK L. major antigens were synthesized in the pLEXSY-neo 2.1 plasmid and cloned into E. coli strain Top10, and after being linearized with the SwaI enzyme, they were transfected into the genome of L. tarentolae. The L. tarentolae-LACK/KMP11/EGFP in the stationary phase with CpG ODN as an adjuvant was used for vaccination in BALB/c mice. Vaccination was performed into the left footpad. Three weeks later, the booster was injected in the same manner. To examine the effectiveness of the injected vaccine, pathogenic L. major (MRHO/IR/75/ER) was injected into the right footpad of all mice three weeks following the booster vaccination. In order to assess humoral immunity, the levels of IgG1, and IgG2a antibodies before and 6 weeks after the challenge were studied in the groups. In addition, in order to investigate cellular immunity in the groups, the study measured IFN-γ, IL-5, TNF-α, IL-6 and IL-17 cytokines before, 3 weeks and 8 weeks after the challenge, and also the parasite load in the lymph node with real-time PCR.

Results

The lowest level of the parasitic load was observed in the G1 group (mice vaccinated with L. tarentolae-LACK/KMP11/EGFP with CpG) in comparison with other groups (L. tarentolae-LACK/KMP11/EGFP +non-CpG (G2); L. tarentolae-EGFP + CpG (G3, control); L. tarentolae-EGFP + non-CpG (G4, control); and mice injected with PBS (G5, control). Moreover, the evaluation of immune response showed a delayed-type hypersensitivity towards Th1.

Conclusions

According to the results of this study, the live recombinant vaccine of L. tarentolae-LACK/KMP11/EGFP with the CpG adjuvant reduced the parasitic load and footpad induration in infected mice. The long-term effects of this vaccine can be evaluated in volunteers as a clinical trial in future planning.

Interleukin-27 Functional Duality Balances Leishmania Infectivity and Pathogenesis

IL-27 is a cytokine that exerts diverse effects on the cells of innate and adaptive immune systems. Chiefly expressed in macrophages and dendritic cells during the early phase of Leishmania infection, IL-27 contributes to the protection against L. major infection but suppresses the protective Th1 response against L. donovani, L. infantum, L. amazonensis and L. braziliensis infections, suggesting its functional duality. During the late stage of Leishmania infection, IL-27 limits the immunopathogenic reactions and tissue damages. Herein, we analyze the mechanism of the functional duality of IL-27 in the resistance or susceptibility to Leishmania infection, prompting IL-27 for anti-Leishmanial therapy.

Molecular characterization of ocular dirofilariasis: a case report of Dirofilaria immitis in south-eastern Iran

Background

Dirofilariasis is a zoonotic parasitic infection transmitted from animals to humans by culicid mosquitoes. Although the disease can be caused by Dirofilaria spp. including Dirofilaria immitis and Dirofilaria repens, human ocular dirofilariasis due to D. immitis is relatively rare in the world. This study was aimed to present a case of ocular dirofilariasis caused by D. immitis in southeastern Iran.

Case presentation

A nematode extracted from the right eye of a 69-year-old man referred with clinical symptoms including itching and redness was examined. After the morphometric analysis, Dirofilaria parasite was detected. Afterwards, a piece of worm body was cut and DNA was extracted and a 680-bp gene fragment amplification and nucleotide sequencing were performed. Phylogenetic analysis revealed a D. immitis roundworm as the causative agent of infection. The patient was treated with antibiotics and corticosteroid and followed up for 1 month.

Conclusion

The present study provides the second report on ocular dirofilariasis caused by D. immitis isolated from a human in southeast Iran. Based on the available evidence, dirofilariasis in dogs has significantly increased in endemic areas such as Iran. Therefore, physicians should be aware of such zoonotic nematodes so as to take proper and timely action and treatment against the disease.

Murine cathelicidin: as a host defensive response against Leishmania major infection

Leishmaniasis is a serious global challenge with neither efficacious prophylactic vaccine nor effective and safe therapeutic measures. Cathelicidins, members of antimicrobial peptides family, are small proteins of innate immunity system, which represent a protective barrier against a number of potential pathogens in living organisms. The murine cathelicidin or cathelin-related antimicrobial peptide (CRAMP) is expressed by a variety of cells or tissues, and highly resembles to human cathelicidin (LL-37). It is naturally expressed at a low concentration in adolescent age, but extensively increases during cutaneous infections. Despite its important role, it has less been investigated in parasitic infections. Among all cells, macrophages and skin cells are the two important cells that directly have a relationship with Leishmania major parasites. The present study aimed to show whether cathelicidins protect their hosts following cutaneous leishmaniasis due to L. major parasites. Both in vitro and in vivo models of L. major infection were established by exposing of J744 cell line (murine macrophages) and BALB/c mice with the stationary phase of L. major promastigotes for 24 h and 7 days. The findings revealed that both macrophages and skin cells significantly (p < 0.05) expressed a high level of CRAMP gene and peptide after challenging with L. major parasites. Thus, our data suggest a protective role for cathelicidins against infections caused by L. major parasites. This experimental model could be considered as a novel potential vaccine candidate for planning future control strategy against human leishmaniasis.

The potential role of nicotinamide on Leishmania tropica: An assessment of inhibitory effect, cytokines gene expression and arginase profiling

Leishmaniasis represents a major health concern worldwide which has no effective treatment modality. Nicotinamide (NAm) has been used for a wide range of applications from anticancer to antimicrobial usage. This study aimed to assess the effect of NAm combination on Leishmania tropica Inhibition, as well as on cytokines gene expression and arginase (ARG) activity in L. tropica-infected macrophages in an in vitro model. The leishmanicidal effects of NAm and Glucantime (meglumine antimoniate, MA) alone and in combination (NAm/MA) were evaluated using a colorimetric assay and macrophage model. Additionally, immunomodulatory effects and enzymatic activity were assessed by analyzing Th1 and Th2 cytokines gene expression and ARG level, respectively, in infected macrophages treated with NAm and MA, alone and in combination. Findings indicated that the NAm/MA combination demonstrated greater inhibitory effects on L. tropica promastigotes and amastigotes compared with each drug individually. Docking results proved the affinity of NAm to IFN-γ, which can affirm the increased levels of IFN-γ, IL-12p40 and TNF-α as well as reductions in IL-10 secretion with a dose-response effect, especially in the combination group. The NAm/MA combination also showed a significant reduction in the level of ARG activity at all concentrations used compared to each drug individually. These findings indicate higher effectiveness of NAm plus MA in reducing parasite growth, promoting immune response and inhibiting ARG level. This combination should be considered as a potential therapeutic regimen for treatment of volunteer patients with anthroponotic cutaneous leishmaniasis (ACL) in future control programs.

Epidemiological and molecular studies on Echinococcus granulosus from free-roaming dogs in Southeast Iran

Background and Aim:

Cystic echinococcosis (CE), as a major zoonotic helminth infection, imposes remarkable socioeconomic burden on many endemic countries across the world, including Iran. Due to the high importance of free-roaming dogs in the transmission of CE, epidemiological and molecular studies in this type of hosts are required in the endemic regions. This study aimed to investigate the epidemiology and genotyping of Echinococcusgranulosus isolated from stray dogs in Kerman, Southeast Iran.

Materials and Methods:

Eighty-four samples were isolated from stray dogs in the city and suburbs of Kerman in coordination with the health authorities and the municipality office for rabies control and dog population management. Dog demographic data, including age and sex were collected. The worm was isolated by necropsy and genomic DNA was extracted and partial cytochrome c oxidase subunit 1 gene was amplified using specific primers. Phylogenetic and Templeton-Crandall-Sing (TCS) network analyses were carried out on the sequence data.

Results:

The overall prevalence of CE in the surveyed dogs was 10.7% (9/84 cases). Out of 84 stray dogs, 33 (39.3%) and 51 (60.7%) cases were male and female, respectively. There was not a statistically significant difference between the infection and gender of dogs. However, infection is shown more in dogs under one year of age with a statistically significant difference (p<0.05). The results of molecular studies indicated E. granulosus G1 genotype for all isolates. The high presence of free-roaming dogs in urban and peri-urban areas and high frequency of parasite in this animal is a risk factor for humans in the region. Haplotype sequence analysis on the dog isolates revealed a close relationship with other E. granulosus isolates in Kerman.

Conclusion:

The findings of this study provide evidence-based data about the epidemiological and molecular characteristics of CE in dog definitive hosts of Southeast Iran. Further studies are required to understand the prevalence and parasite genotypes in dogs in Iran.

Transient knockdown of Nucleoside transporter 4 gene expression as a therapeutic target in Leishmania major by antisense RNA: In vitro and in vivo studies

Background & objectives

Leishmania parasites cause various clinical symptoms in humans such as cutaneous ulcers and fatal visceral diseases. These parasites cannot synthesize purine rings de novo and must uptake purines from their hosts via salvage. Salvage is regulated by permeases in the cell membrane. There are hundreds of membrane transporter proteins to receive nutrients in Leishmania. Nucleoside transporter 4 (NT4) is one of the purine transporters that is involved in enhancing the uptake of adenine in Leishmania major. They are important new drug targets for the treatment of leishmaniasis because they can be used to transport toxic purine analogs to kill parasitic cells, thus preventing the progression of the infection. The present study was conducted to silence the NT4 nucleobase involved in the salvage pathway to interrupt purine nucleotide membrane transport in the cells of L. major.

Methods

In this study, a 502 bp segment of NT4 gene sequence was selected and designed as antisense transcripts after insertion in the parasite. The NT4 construct was transfected into L. major promastigotes for in vitro study of gene expression. Then, BALB/c mice infected with transgenic Leishmania and wild-type strain along with the number and size of lesions were studied in vivo.

Results

The study showed that relative expression of NT4 gene in mutant Leishmania was lower than in the control on Day 3 to 20. The percentages and the number of amastigotes in infected macrophages with wild-type strain L. major were more than infected macrophages with mutant parasites. Infected BALB/c mice with transgenic Leish- mania showed a lower number and size of lesions than the BALB/c mice infected with wild-type strain.

Interpretation & conclusion

The results of the study indicated that the use of antisense RNA reduced NT4 gene expression in L. major. Further, studies are needed to ascertain that the use of antisense can be considered as a new treatment for leishmaniasis.

Antileishmanial Activity of Niosomal Combination Forms of Tioxolone along with Benzoxonium Chloride against Leishmania tropica

In this study, we carried out extensive in vitro studies on various concentrations of tioxolone along with benzoxonium chloride and their niosomal forms against Leishmania tropica. Niosomes were prepared by the hydration method and were evaluated for morphology, size, release study, and encapsulation efficiency. This study measured leishmanicidal activity against promastigote and amastigote, apoptosis and gene expression levels of free solution and niosomal-encapsulated tioxolone along with benzoxonium chloride. Span/Tween 60 niosome had good physical stability and high encapsulation efficiency (more than 97%). The release profile of the entrapped compound showed that a gradual release rate. The combination of niosomal forms on promastigote and amastigote were more effective than glucantime. Also, the niosomal form of this compound was significantly less toxic than glucantime (P≤0.05). The flowcytometric analysis on niosomal form of drugs showed that higher number of early apoptotic event as the principal mode of action (89.13% in 200 μg/ml). Also, the niosomal compound increased the expression level of IL-12 and metacaspase genes and decreased the expression level of the IL-10 gene, which further confirming the immunomodulatory role as the mechanism of action. We observed the synergistic effects of these 2 drugs that induced the apoptotic pathways and also up regulation of an immunomodulatory role against as the main mode of action. Also, niosomal form of this combination was safe and demonstrated strong anti-leishmaniasis effects highlights further therapeutic approaches against anthroponotic cutaneous leishmaniasis in future planning.

Leishmania species-dependent functional duality of toll-like receptor 2

Toll-like receptors (TLRs) are a subset of pattern recognition receptors (PRR) in innate immunity and act as a connecting link between innate and adaptive immune systems. During Leishmania infection, the activation of TLRs influences the pathogen-specific immune responses, which may play a decisive role in determining the outcome of infection, toward elimination or survival of the pathogen. Antigen-presenting cells (APCs) of the innate immune system such as macrophages, dendritic cells (DCs), neutrophils, natural killer (NK) cells, and NKT cells express TLR2, which plays a crucial role in the parasite recognition and elicitation of immune responses in Leishmania infection. Depending on the infecting Leishmania species, the TLR2 pathways may result in a host-protective or a disease-exacerbating response. While Leishmania major and Leishmania donovani infections trigger TLR2-related host-protective and non-protective immune responses, Leishmania mexicana and Leishmania infantum infections are reported to elicit TLR2-mediated host-protective responses and Leishmania amazonensis and Leishmania braziliensis infections are reported to evoke a disease-exacerbating response. These findings illustrate that TLR2-related effector functions are diverse and may be exerted in a species- or strain-dependent manner. TLR2 agonists or antagonists may have therapeutic potentials to trigger the desired immune response during leishmaniasis. In this review, we discuss the TLR2-related immune responses during leishmaniasis and highlight the novel insights into the possible role of TLR2-driven resistance or susceptibility to Leishmania.

Associated-risk determinants for anthroponotic cutaneous leishmaniasis treated with meglumine antimoniate: A cohort study in Iran

Background

The control of cutaneous leishmaniasis (CL) is facilitated by knowledge of factors associated with the treatment failures in endemic countries. The aim of this evaluation was to identify the potential risk determinants which might affect the significance of demographic and clinical characteristics for the patients with anthroponotic CL (ACL) and the outcome of meglumine antimoniate (MA) (Glucantime) treatment.

Methodology/Principal findings

This current was executed as a cohort spanning over a period of 5 years which centered in southeastern part of Iran. Altogether, 2,422 participants were evaluated and 1,391 eligible volunteer patients with ACL caused by Leishmania tropica were included. Overall, 1,116 (80.2%) patients received MA intraleisionally (IL), once a week for 12 weeks along with biweekly cryotherapy, while 275 (19.8%) patients received MA alone (20 mg/kg/day for 3 weeks) (intramuscular, IM). The treatment failure rate in ACL patients was 11% using IL combined with cryotherapy plus IM alone, whilst 9% and 18.5% by IL along with cryotherapy or IM alone, respectively. Multivariate logistic regression model predicted 5 major associated-risk determinants including male (odds ratio (OR) = 1.54, confidence interval (CI) = 1.079–2.22, p = 0.018), lesion on face (OR = 1.574, CI = 1.075–2.303, p = 0.02), multiple lesions (OR = 1.446, CI = 1.008–2.075, p = 0.045), poor treatment adherence (OR = 2.041, CI = 1.204–3.46, p = 0.008) and disease duration > 4 months (OR = 2.739, CI = 1.906–3.936, p≤0.001).

Conclusions/Significance

The present study is the original and largest cohort of ACL patients who treated with MA. A comprehensive intervention and coordinated action by the health authorities and policy-makers are crucial to make sure that patients strictly follow medical instructions. Early detection and effective therapy < 4 months following the onset of the lesion is critical for successful treatment of the patients. Since a significant number of patients are still refractory to MA, reducing man-vector exposure and development of new effective alternative drugs are essential measures against ACL due to L. tropica.

Cutaneous leishmaniasis (CL) is a serious neglected tropical disease with social stigma and associated disfiguring with health burden, especially in poor endemic regions of the world. Iran is among the seven high burden CL-infected countries. Limited data are available in regarding to CL treatment and related risk determinants. Parasitologically confirmed ACL patients caused by Leishmania tropica were treated over a 5-year period (2012–2016), with IL meglumine antimoniate (MA) (Glucantime), combined with cryotherapy or with IM MA alone. The objective of this study was to identify the potential risk factors that are associated with response to treatment. The ensuing results with both therapeutic routes identified 5 major risk determinants namely male patients, lesion on face, multiple lesions, poor treatment regimen and disease duration >4 months. The extent to which medical instructions related to patients, therapy and the healthcare system should be seriously monitored. This requires multidisciplinary actions to address specific barriers which directly threaten the treatment outcome. Furthermore, early detection and prompt treatment <4 months following the disease duration together with implementations of public health education and prophylactic measures should receive priority in high risk areas.

Niosomal formulation of amphotericin B alone and in combination with glucantime: In vitro and in vivo leishmanicidal effects

This study aimed to evaluate the efficacy of glucantime and amphotericin B (AmB) encapsulated in niosome against cutaneous leishmaniasis (CL) using in vitro and in vivo models. The niosomal formulations of the drugs alone and in combination were prepared and characterized. Subsequent to the examination of their cytotoxicity, their efficacy was evaluated using an in vitro MTT assay, macrophage model, flow cytometry, and gene expression profiling. For evaluation of therapeutic effect of niosomal combination on the lesion induced by Leishmania major in inbred BALB/c mice, the size of lesions and number of parasites in spleen was assessed. The niosomal formulations demonstrated significantly greater inhibitory effects compared with the non-niosomal forms when the IC₅₀ was considered. The niosomal combination showed an increase in the apoptotic values and gene expression levels of IL-12 and metacaspase and a decrease in the levels of IL-10 with a dose-response effect. The niosomal combination was also effective in reducing the lesion size and splenic parasite burden in mice. Our findings indicated that there is a synergistic effect between AmB and glucantime in niosomal form in the inhibition of intracellular and extracellular forms of L. tropica. Additionally, the in vivo results on L. major suggest that topical niosomal formulation could be useful in the treatment of CL.

Expansion of urban cutaneous leishmaniasis into rural areas of southeastern Iran: Clinical, epidemiological and phylogenetic profiles explored using 7SL high resolution melting-PCR analysis

Cutaneous leishmaniasis (CL) has increased remarkably in Iran and has expanded into new areas. The present study aimed to assess the emerging CL outbreak in southeastern Iran using high resolution melting-polymerase chain reaction (HRM-PCR) and phylogenetic analysis using the 7SL RNA gene marker. A cross-sectional and analytical survey was conducted during a house-to-house census of 11,021 inhabitants in Narmashir County in southeastern Iran in 2016. The cases were detected by direct smear microscopic examination and sequencing and were characterized using the 7SL RNA gene. All age groups and sexes were equally affected. Most were single lesions (70.7%). The hands (55.2%) and face (37.9%) were the main sites of involvement. The disease was more common among illiterate persons. Sequencing and HRM-PCR revealed that Leishmania tropica (accession no. MH632168 Qale-Shahid) was the principal causative agent of anthroponotic CL (ACL) in new areas of expansion. This is the first emergence of ACL in rural areas of Narmashir County. Based on the molecular data, the causative parasite species confirmed to be L. tropica. Sequencing and phylogenetic analysis indicated that a single clone of the organism derived from a single source has spread into the affected villages. Construction of a main road, population movement and recent urbanization in the area are likely the major factors associated with the establishment of this new outbreak. This study was essential to enable the planning of effective therapeutic and prophylactic measures to control the disease.

A Novel Niosomal Combination of Selenium Coupled with Glucantime against Leishmania tropica

There is no effective treatment modality available against different forms of leishmaniasis. Therefore, the aim of this study was to improve the penetration and efficacy of selenium and glucantime coupled with niosomes and compared them with their simple forms alone on in vitro susceptibility assays. In this study, the niosomal formulations of selenium and in combination with glucantime were prepared. The size and morphology of the niosomal formulations were characterized and the effectivity of the new formulation was also evaluated using in vitro MTT assay, intra-macrophage model, and gene expression profile. From the results obtained, no cytotoxicity effect was observed for niosomal and simple forms of drugs, as alone or in combination. Niosomal formulations of the drugs significantly showed more inhibitory effects (P ≤ 0.001) than the simple drugs when the selectivity index was considered. The gene expression levels of Interleukin (IL-10) significantly decreased, while the level of IL-12 and metacaspase significantly increased (P ≤ 0.001). The results of the present study showed that selenium plus glucantime niosome possess a potent anti-leishmanial effect and enhanced their lethal activity as evidenced by the in vitro experiments.

Host's immune response in unresponsive and responsive patients with anthroponotic cutaneous leishmaniasis treated by meglumine antimoniate: A case-control study of Th1 and Th2 pathways

The objective of the present study was to compare the host's immune responses between unresponsive and responsive patients with anthroponotic cutaneous leishmaniasis (ACL) treated by meglumine antimoniate. A case-control study was carried out in an endemic focus in Iran. Blood samples were taken from patients and peripheral blood mononuclear cells (PBMCs) were isolated. Two wells were considered for each isolate of unresponsive and responsive patients; one was exposed to L. tropica (Lt-stimulated cells) and the other remained non-exposed (non-stimulated cells). After 24 h of incubation, whole RNA was extracted from each sample. Real-time quantitative PCR was carried out to confirm the differences in expression levels of IL-12 P40, IFN-γ, IL-1β, IL-4 and IL-10 among isolates. Data were analyzed and P < 0.05 was considered to be statistically significant. In our study, Lt-stimulated cells and non-stimulated cells in unresponsive groups demonstrated significantly lower expression levels of IL-1β, IL-12 P40 and IFN-γ genes and higher expression levels of IL-4 and IL-10 genes, compared to Lt-stimulated cells and non-stimulated cells in responsive groups. There was a negative correlation between IL-12 P40 with IL-10 and IL-1β with IL-10 in ACL Lt-stimulated cells in unresponsive group, while a positive correlation between IL-12 P40 with IL-1β and IL-12 P40 with IFN-γ in ACL Lt-stimulated cells in responsive group. Probably, different immune responses caused by various factors play a major role in the pathogenesis and development of unresponsiveness in ACL patients. The profile and timing of cytokine production correlated well with the treatment outcome of Leishmania infection.

Protection induced by Leishmania Major antigens and the imiquimod adjuvant encapsulated on liposomes in experimental cutaneous leishmaniasis

There is a need for new, effective, and less expensive and toxic treatment for Leishmaniasis. It seems that the use of a suitable adjuvant and a delivery system is effective in inducing immune reactions for protection. Liposomes can be applied as immunoadjuvants to trigger immune reactions to different antigens. The adjuvant effects of imiquimod using DSPC liposomes containing SLA (soluble Leishmania antigens) were studied on the type and intensity of the produced immune reaction to the challenge of Leishmania major in BALB/c mice. Liposomes were produced by the lipid film procedure. BALB/C mice were immunized subcutaneously, three times at 2-week intervals and with various formulations. Lesion development and the parasite burden in the spleens and feet after the challenge with Leishmania major, Th1 cytokine (IFN-γ), and the IgG isotype titration were assessed to evaluate the induced immune reaction and the protection level. The group of mice immunized with Liposome DSPC +Imiquimod +SLA revealed less severe footpad swelling, being significantly different (P < .05) from other groups. A higher level of IgG2a and IFN-γ secretion was observed in the mice immunized with Liposome DSPC +Imiquimod +SLA than the control group. These observations imply that the DSPC liposome containing imiquimod induces the Th1 immune response that is protective against the challenge of Leishmania major.