The outcome of arginase activity inhibition in BALB/c mice hosting Leishmania tropica

Two species of Leishmania (L), L. tropica and L. major, are among the main causative agents of cutaneous leishmaniasis. Arginase (ARG) is an essential enzyme for cell growth, thus an attractive drug target. In this study, we tried to survey the inhibitory impact of ARG by nor-NOHA (N-ω-hydroxy-L-nor-arginine) on in vivo infection caused by L. tropica. BALB/c mice were inoculated with L. tropica^EGFP-LUC (Ltrop) or L. major^EGFP-LUC (Lmj) and then were treated by nor-NOHA. ARG inhibitor only indicated a delay in generation of a cutaneous lesion in inoculated footpad with nor-NOHA-Ltrop and nor-NOHA-Lmj. ARG activity has been significantly reduced in nor-NOHA-Ltrop group. In this group, ARG activity inhibition correlated with increased levels of nitric oxide (NO). In both inoculated mice with Ltrop or Lmj, parasite load showed a significant decrease at later steps during the CL course post-treatment. In vivo bioluminescence intensity did not show any ARG's inhibitory effect on treated-Ltrop. The findings verified that the ARG activity may partially control the L. tropica infection in BALB/c mice through reduction of parasite proliferation and parasite killing through NO generation. This effect is dose-dependent.     

An overview of a diagnostic and epidemiologic reappraisal of cutaneous leishmaniasis in Iran

Cutaneous leishmaniasis (CL) is a widespread tropical infection which has a high incidence rate in Iran. Leishmania tropica, the causative agent of anthroponotic cutaneous leishmaniasis (ACL), and Leishmania major, which causes zoonotic cutaneous leishmaniasis (ZCL), are endemic in various parts of Iran with a high incidence rate. The aim of this study was to evaluate the reappraisal of the diagnosis and epidemiology of CL in Iran, by different clinical, parasitological and molecular assays among patients suspected of CL referred to the Department of Parasitology, at the Pasteur Institute of Iran during 2006–2009. Two hundred samples from patients with ulcerative skin lesions were collected, clinical analyses were applied, data questionnaire was completed and samples were examined for CL by using both direct microscopic and culture methods. Moreover, PCR assay was applied for detection of Leishmania species in CL isolates resulting from parasitological assay. Clinical observation revealed that the majority (58%) of lesions was single; double lesions were observed in 22% of patients, and only 20% of CL had multiple lesions. Out of 200 patients, Leishman body was observed in 77 samples (38.5%) by direct smear and 40% by cultivation assay. Most patients (21.3%) had a travel history to the Isfahan province, one of the most important endemic areas of CL located in center of Iran. PCR assay by kDNA indicated 32 and 18 out of 50 isolates respectively had similar patterns with standard L. major and L. tropica. In conclusion, clinical manifestations and an appropriate diagnostic assay with a parallel molecular characterization of CL may lead to a screening evaluation of disease, prognosis, treatment and control strategies.     

Arginase activity of Leishmania isolated from patients with cutaneous leishmaniasis

Cutaneous leishmaniasis (CL) is one of the most important vector‐borne parasitic diseases, highly endemic in Iran, and its prevalence is increasing all over the country. Arginase (ARG) activity in isolated Leishmania parasites from CL patients is yet to be explored. This study aimed to compare the ARG activity of isolated Leishmania promastigotes from CL patients with a standard strain of Leishmania major and its influences on the disease pathogenesis. We recruited 16 confirmed CL patients from Qom Province, in central Iran; after detection of Leishmania species using PCR‐RFLP, we assessed the levels of ARG in the isolated promastigotes and determined the parasites’ growth rate. Only L. major was identified from CL patients. The level of ARG activity in the isolated Leishmania promastigotes from CL patients was significantly higher than that obtained from the standard strain of L. major. No significant correlations between ARG activity and lesion size, number or duration were observed; in contrast, a significant negative correlation was seen between ARG level and Leishmania’ growth rate. The obtained results suggest that increased ARG expression and activity in the isolated Leishmania promastigotes might contribute to the higher parasite infectivity and play a major role in the pathogenicity of the CL.     

Leishmania tropica in Egypt: an undesirable import

Cutaneous as well as visceral leishmaniasis has been previously reported in Egypt. The former clinical manifestation is attributed to Leishmania major, the latter to L. infantum. In this study, L. tropica was isolated from an Egyptian labourer returning from Saudi Arabia. Amastigotes were detected by both Giemsa staining and indirect immunofluorescence using rabbit anti-gp63. Promastigotes from Schneider's medium were typed isoenzymatically as L. tropica. In view of the emerging threat of visceralization of L. tropica, the potential risk for its transmission in Egypt is discussed.     

Emergence of a new focus of anthroponotic cutaneous leishmaniasis due to Leishmania tropica in rural communities of Bam district after the earthquake, Iran

Objectives To describe a new emerging focus of anthroponotic cutaneous leishmaniasis (ACL) due to Leishmania tropica in rural areas of Dehbakry county, south‐eastern Iran, after the earthquake of 2003. Methods House‐to‐house survey of 3884 inhabitants for active leishmaniasis lesions or scars. The diagnosis was confirmed by smears, cultures and identification of the parasite by polymerase chain reaction (PCR). Results All age groups were affected, although patients ≤10 years of age showed the highest rate of infection (P = 0.0001). The overall prevalence rate was 5.3%; 6.3% in females and 4.3% in males. Of 204 cases, 1.8% had active sores and 3.5% had scars, with a significant difference between the sexes (P = 0.005). 47% of the lesions were on the face and 77.9% had one lesion. The incidence rose gradually 2004–2005, but grew exponentially 2006–2008. Electrophoresis of PCR products indicated that L. tropica was the causative agent. Conclusions The current emergence was unexpected in this rural locality, where no previous history of CL was recorded. According to our knowledge this is the first report of a gradually establishing new ACL focus in rural communities after the 2003 earthquake.     

Identification of Old World Leishmania species by PCR–RFLP of the 7 spliced leader RNA gene and reverse dot blot assay

The aim of the study was to assess the 7SL RNA PCR followed by restriction fragment length polymorphism (RFLP) and reverse dot blot (RDB) assays for use in identification of Old World Leishmania species. Species‐specific RFLP patterns were obtained for Leishmania major, Leishmania tropica and the Leishmania donovani complex when the 7SL RNA PCR product was digested with the restriction enzyme BsuRI, an isoschizomer of HaeIII. For the RDB assay, biotin‐labelled 7SL RNA amplicons were hybridized to Leishmania genus‐specific and species‐specific oligonucleotide probes immobilized onto a membrane. The Old World Leishmania species could be distinguished by using five probes: one that was a genus‐specific probe and hybridized to all Leishmania species (Lc), two that were specific for L. major (Lm1 and Lm2), one that was specific for L. tropica (Lt) and one that detected both L. major and L. tropica (Lmt). The PCR–RDB was 10 times more sensitive than 7SL PCR and can detect <1 parasite. In addition, the identification of species was easier and more reliable than with 7SL PCR–RFLP. 7SL PCR–RFLP detected parasites in 50 of 57 clinical samples, whereas PCR–RDB detected 53 and 55 were detected by amplification of kinetoplast (k) DNA. The 7SL RNA PCR has proven useful for direct diagnosis of Old World leishmaniasis, especially when combined with the RBD assay for species identification.     

A molecular and parasitological survey on cutaneous leishmaniasis patients from historical city of Kashan in Isfahan province,center of Iran

ObjectiveTo study cutaneous leishmaniasis (CL) for identifying the dominant Leishmania species on CL patients referred to medical health centers of historical Kashan city and suburbs located in Isfahan province in central part of Iran during 2010 to 2011.MethodsFrom 137 CL cases, were microscopically positive, the skin lesion serosity materials of 103 cases were cultured in monophasic culture media (RPMI 1 640). We used the PCR-RFLP method for characterization the Leishmania isolates, by using specific internal transcribed spacer (ITS1) primers and HAEШ as the restriction fast enzyme. DNA was extracted from 63 samples.ResultsL. tropica is main species in 58 (92.1%) cases and L. major is identified in 5 (7.9%) cases. Indeed randomly two isolates were the species characterized as L. major produced ulcer at the base tail of BALB/c mice after 3 weeks but from three L. tropica isolates none of them produced any lesion during 6 months post inoculation.ConclusionsThe parasitological, epidemiological aspect and molecular methods of this study showed that, Kashan and suburb are anthroponetic CL area despite this city located in Isfahan province as an ancient focus of zoonotic CL in Iran.     

Amplified fragment length polymorphism (AFLP) analysis is useful for distinguishing Leishmania species of visceral and cutaneous forms

The Leishmania strains belonging to cutaneous leishmaniasis (CL) and visceral leishmaniasis (VL) have been reported to possess close homology in genome profiles. To confirm this on genetic basis an attempt was made to differentiate Leishmania major; Leishmania tropica and Leishmania donovani genetically for the first time using amplified fragment length polymorphism (AFLP)—a high throughput DNA fingerprinting technique. The objective of this research work was to identify DNA markers of CL and VL. Ten combinations of selective primers detect a total of 1487 informative AFLP marker. Percentage of polymorphism was 45.12%. Three hundred and thirty-seven unique AFLP markers were also identified in three species of Leishmania. A clear distinction was revealed between L. major and L. donovani. It was inferred by AFLP analysis that a higher rate of polymorphisms occurred among Leishmania species which indicate the distinguished pattern of the disease cause by Leishmania, i.e. VL and CL. Analysis based on polymorphic AFLP markers revealed considerably high genetic variation among the genome of these species which was sufficient to distinguish between CL and VL.     

First molecular identification of Leishmania species in a new endemic area of cutaneous leishmaniasis in Lorestan,Iran

ObjectiveTo identify Leishmania using PCR.MethodsThis study was conducted from April 2009 to March 2011 in order to identify Leishmania species in a new endemic area of CL in Lorestan, Iran. Samples were taken from 62 patients that referred to the health centers in different cities of Lorestan province, the presence of Leishmania was confirmed using direct smear and then grown in NNN media and mass cultured in RPMI 1 640 medium supplemented with 10% heat-inactivated fetal bovine serum. DNA was extracted from cultured promastigotes and used in ITS-PCR.Results45(72.6%) samples out of 62 showed a band in the range of 485 bp and 17 (27.4%) with a band in the range of 626 bp which were similar to standard strains of Leishmania tropica(L. tropica) and Leishmania major(L. major), respectively. 50 (65.80%) of samples were collected from people with no history of travel in at least a year prior to the onset which shows that indigenous source of infection.ConclusionsSince the vector and reservoir of the two species are different, so precise and extensive control and prevention methods should be designed and carried out.     

Cutaneous leishmaniasis caused by Leishmania (L.) major infection in Sindh province, Pakistan

Leishmaniasis is endemic in Pakistan and is wide-spread throughout the country. Polymerase chain reaction (PCR) was performed to identify the Leishmania species present in cutaneous leishmaniasis (CL) patients from new endemic areas of the central part of Sindh province, Pakistan. The PCR primers used were designed for the identification and differentiation of Leishmania (Leishmania) major and Leishmania (Leishmania) tropica species, and PCR bands at 620 and 830 bp of the parasite-specific kinetoplast DNA sequences was identified for L. (L.) major and L. (L.) tropica, respectively. Among a total of 144 DNA samples purified from the skin biopsies of clinically suspected CL patients, 108 (75%) were positive for PCR amplification. Out of the 108 cases, 105 (97.2%) were determined to be positive for L. (L.) major infection, and 3 (2.8%) were positive for L. (L.) tropica infection. It was concluded that CL caused by L. (L.) major is the main source of infection in the central part of Sindh province in Pakistan. This rapid screening technique could be used for the diagnosis of a large number of samples from skin lesions, which commonly contain other bacterial and fungal infections.     

Leishmania major: genetic heterogeneity of Iranian isolates by single-strand conformation polymorphism and sequence analysis of ribosomal DNA internal transcribed spacer

Protozoan parasites of Leishmania major are the causative agents of cutaneous leishmaniasis in different parts of Iran. We applied PCR-based methods to analyze L. major parasites isolated from patients with active lesions from different geographic areas in Iran in order to understand DNA polymorphisms within L. major species. Twenty-four isolates were identified as L. major by RFLP analysis of the ribosomal internal transcribed spacer 1 (ITS1) amplicons. These isolates were further studied by single-strand conformation polymorphism (SSCP) analysis and sequencing of ITS1 and ITS2. Data obtained from SSCP analysis of the ITS1 and ITS2 loci revealed three and four different patterns among all studied samples, respectively. Sequencing of ITS1 and ITS2 confirmed the results of SSCP analysis and showed the potential of the PCR-SSCP method for assessing genetic heterogeneity within L. major. Different patterns in ITS1 were due to substitution of one nucleotide, whereas in ITS2 the changes were defined by variation in the number of repeats in two polymorphic microsatellites. In total five genotypic groups LmA, LmB, LmC, LmD and LmE were identified among L. major isolates. The most frequent genotype, LmA, was detected in isolates collected from different endemic areas of cutaneous leishmaniasis in Iran. Genotypes LmC, LmD and LmE were found only in the new focus of CL in Damghan (Semnan province) and LmB was identified exclusively among isolates of Kashan focus (Isfahan province). The distribution of genetic polymorphisms suggests the existence of distinct endemic regions of L. major in Iran.     

A2 gene of Old World cutaneous <Emphasis Type="Italic">Leishmania</Emphasis> is a single highly conserved functional gene

Background  

Leishmaniases are among the most proteiform parasitic infections in humans ranging from unapparent to cutaneous, mucocutaneous or visceral diseases. The various clinical issues depend on complex and still poorly understood mechanisms where both host and parasite factors are interacting. Among the candidate factors of parasite virulence are the A2 genes, a family of multiple genes that are developmentally expressed in species of the Leishmania donovani group responsible for visceral diseases (VL). By contrast, in L. major determining cutaneous infections (CL) we showed that A2 genes are present in a truncated form only. Furthermore, the A2 genomic sequences of L. major were considered subsequently to represent non-expressed pseudogenes [1]. Consequently, it was suggested that the structural and functional properties of A2 genes could play a role in the differential tropism of CL and VL leishmanias. On this basis, it was of importance to determine whether the observed structural/functional particularities of the L. major A2 genes were shared by other CL Leishmania, therefore representing a proper characteristic of CL A2 genes as opposed to those of VL isolates.     

Olive (Olea europaea) leaf extract alters the cytokine profile of Leishmania major‐infected macrophages: New insight into the underlying mechanism

This study aimed to identify the effects of olive leaf extract (OLE) on IFNγ, TNFα, TGFβ and nitric oxide (NO) resulted from macrophages infected with Leishmania major (L. major) amastigotes in the culture medium. High‐performance liquid chromatography (HPLC) was used to analyse the level of Oleuropein in plant extract. To evaluate the immunomodulatory effects of OLE, the isolated BALB/c mice peritoneal macrophages were infected with L. major promastigotes and treated with 6.25, 12.5 and 25 μg/mL concentrations of OLE. To assess the cytokines, supernatants of cell cultures were harvested after 12, 24 and 48 hours. Cytokine production was evaluated by ELISA. Nitrite accumulation in the culture medium was assessed using the Griess reaction. The level of Oleuropein in the extract was 18.45% by HPLC. According to results, the production of IFNγ and TNFα was significantly increased when the infected and/or not infected macrophages with L. major promastigotes were affected by different concentrations of OLE. Conversely, the production of TGFβ was significantly decreased under the same conditions. Furthermore, the colorimetric determination of NO accumulation in the culture medium indicated that OLE has no effect on NO production. The study corroborates the immunomodulatory effects of OLE on L. major‐infected macrophages.     

Sambucus ebulus extract stimulates cellular responses in cutaneous leishmaniasis

This is the first study aiming to determine the therapeutic effects of the Sambucus ebulus aquatic extract as an antileishmanial herbal drug and evaluate the immune responses in Leishmania major major infected BALB/c mice. The antileishmanial activity of S ebulus aquatic extract was evaluated using MTT test as well as parasite rescue and transformation assay. Footpad swelling and parasite load of infected mice were measured by several techniques. The immune responses were evaluated by measuring the levels of IFN‐γ, IL‐4, nitric oxide and arginase. The results indicated that S. ebulus can significantly decrease L. major promastigotes and amastigotes viability, but it was not toxic to macrophages. The lesion size, parasite burden and the level of ARG decreased in the treated infected mice, while the IFN‐γ‐to‐IL‐4 ratio and the level of NO increased significantly. Altogether, the S. ebulus extract is an effective compound for killing Leishmania parasite without excessive toxicity to the host cells and can cure the CL by switching the host immune responses towards Th1 response. Thus, it may be a perfect therapeutic option for CL treatment.     

中国利什曼原虫分离株分子核型分析

目的：通过核型分析探讨中国利什曼原虫分离株遗传变异情况。方法：应用脉冲电泳技术对16株中国利什曼原虫分离株基因组核型进行分析。结果：被测分离株分有14条－26条染色体（低于2200kb）被区分，核型差异大多集中于225kb－850kb染色体区域，较大染色体相对保守。其中14株属于杜氏利什曼原虫复合体的分离株存在明显的种内核型差异，但来自同一流行区的分离株核型显示差异较小。所有杜氏利什曼原虫复合体的分离株均含有11条相似染色体带：320kb,350kb,380kb,870kb,910kb,1070kb， 200 kb, 1 250 kb, 1 350 kb, 1 600 kb 和1 900 kb。其中, 从白蛉体内分离出的771 分离株核型显示较为独特, 共分离出26 条染色体带。另两株从大沙鼠体内分离的、先前已分被命名为沙鼠利什曼原虫和都兰利什曼原虫的R12 和R20 分离株显示相近核型。结论: 中国杜氏利什曼原虫复合体内存在明显种内遗传变异, 但亲缘关系越近的分离株核型也越相近。地理环境与媒介白蛉均对杜氏利什曼原虫复合体内遗传变异起一定作用。R12 和R 20 分离株倾向于属于同一个种或两个亲缘关系极近的种。同时, 可见寄生的哺乳动物宿主不同可能与利什曼原虫遗传关系密切。     

我国利什曼原虫RAPD分析

目的　我国不同疫区利什曼原虫分离株的RAPD分析。　方法　用 7种随机引物 ,扩增来自我国 3个疫区 (得自利什曼病患者、病犬及白蛉 )的利什曼原虫分离株和国际标准株 ,并将扩增产物进行聚类分析。　结果　①来自我国山丘疫区及平原疫区的L d .分离株分别聚为两类 ,两者遗传距离较远 ;②来自新疆荒漠疫区、近荒漠疫区及平原地区的L d .XJ771、L d .XJ90 1和L d .XJ80 1聚在一类 ,表明它们的遗传距离较近 ;③山丘疫区虫株中来自病人和病犬的分离株区别不明显 ,两者同源性高 ,表明犬在传播中起着重要作用 ;④印度平原型标准株L d .DD8与我国平原疫区虫株聚在一类 ;⑤L infantum与我国山丘疫区的L d .分离株分属于两类 ;⑥L dJed与平原疫区L d .分离株亲缘关系较近 ;⑦L infantum与L tropica最早聚合 ,遗传距离最近。　结论　我国不同疫区利什曼原虫分离株在基因水平上存有差异。     

Distinct strains of Leishmania major induce different cytokine mRNA expression in draining lymph node of BALB/c mice

Four genotypically distinct strains of L. major collected from persons residing in different endemic areas of cutaneous leishmaniasis in Iran were evaluated in BALB/c mice. Parasite virulence was evaluated by measuring the parasite burden in the lymph nodes. Immunogenicity of the strains was assessed by analysis of cytokines mRNA expression levels in popliteal lymph nodes of the mice in early (3, 16, 40 h) and late (week 1, W3, W5 and W8) time periods after infection. The expression of cytokines mRNA, namely Ifng, Il2,Il4,Il10 and Il12, was quantitated by real‐time PCR. The lowest and the highest parasite loads were induced by Damghan (2·15 ×  10⁷) and Shiraz (9·59 ×  10⁹) strains, respectively. Moreover, Damghan strain elicited higher expression levels of Ifng and Il2 mRNA and the highest ratio of Ifng/Il4 mRNA expression compared with the other strains at 40 h and 8 weeks post‐infection. The results indicate that the inoculation of BALB/c mice with different strains induced high diversity in parasite burden and cytokines gene expression. Amongst the four strains, Damghan strain showed the lowest parasite load and the highest tendency to induce expression of Th1 cytokines gene and might be considered as a safe and immunogenic strain.     

Identification of immunodominant Leishmania major antigenic markers of the early C57BL/6 and BALB/c mice infection stages

The C57BL/6 mouse strain is resistant to Leishmania (L.) major infection and, unlike susceptible BALB/c, develops small self‐healing cutaneous lesions. The specific antibody responses of C57BL/6 and BALB/c mice were previously characterized by the predominance of IgG2a (‘resistant’ isotype associated with Th1) and IgG1 (‘pathogenic’ isotype associated with Th2) antibodies, respectively. In this study, we looked for the presence of antigens able to elicit an exclusive or predominant IgG1 production during the early stages of C57BL/6 lesion development and checked whether they are recognized or not by BALB/c mice. We demonstrate first that IgG2a predominance in C57BL/6 sera occurs only late after infection, whereas in BALB/c, IgG1 antibodies dominate mostly in the early stages. Interestingly, soon after inoculation of live amastigotes, C57BL/6 displayed an exclusive IgG1 reactivity against particular L. major antigens but with MWs different from those identified in BALB/c. Furthermore, mice immunized with killed amastigotes displayed striking differences in their immunodetection profiles, particularly for the IgG1 isotype. Taken together, the observed differences in the specific antibody repertoires between infected mice resulted, at least in part, from immunological events independent from those triggered by the replicating parasite, and bring new insights into the selection of future vaccine candidates.