Intralesional injection of 2% zinc sulfate solution in the treatment of acute old world cutaneous leishmaniasis: a randomized, double-blind, controlled clinical trial

Several in vitro and in vivo studies have shown inhibitory effects of zinc sulfate (ZnSO4) on Leishmania parasites. The objective of this study was to compare the efficacy of intralesional injections of 2% ZnSO4 solution with meglumine antimonate (Glucantime) in the treatment of acute Old World cutaneous leishmaniasis (CL). Seventy-two patients with CL lesions less than 8 weeks were recruited in a randomized, double-blind, clinical trial in an area endemic for Leishmania major after giving written informed consent. They were treated with 6 weekly intralesional injections of either drug. Among 36 patients with 53 lesions treated with ZnSO4 and 36 patients with 53 lesions treated with Glucantime, 13 patients with 19 lesions and 22 patients with 31 lesions completed the trial, respectively. Inadequacy of treatment was the main reason for drop-out in 12 (33.3%) and 2 (5.5%) patients in ZnSO4 and Glucantime groups, respectively (P < .05). Complete re-epithelialization was observed in 2 (10.5%) and 19 (61.3%) lesions 1 week after the end of treatment in the ZnSO4 and Glucantime groups, respectively (P < .05). In conclusion a 6-week course of weekly intralesional injections of 2% ZnSO4 solution was less effective than Glucantime in the treatment of acute Old World CL.     

Leishmanization: use of an old method for evaluation of candidate vaccines against leishmaniasis

To establish the safety and reproducibility of live challenge with Leishmania major, a single frozen stabilate was used in two open, single-arm leishmanization (LZ) trials. A total of 42 inoculations in 28 male adult volunteers were followed until complete healing. Lesions induced by LZ are as diverse as natural infection, but much milder. Total protection was seen in 100% (11/11) of recovered volunteers. LZ used as live challenge to test vaccine candidates reduces the required sample size, is cost effective for surrogate markers studies and will induce protection in the participants who are not protected by candidate vaccines.     

Comparison of topical paromomycin sulfate (twice/day) with intralesional meglumine antimoniate for the treatment of cutaneous leishmaniasis caused by L. major

This is an open study to compare the cure rate of cutaneous leishmaniasis caused by L. major and treated with either paromomycin sulfate or intralesional injection of meglumine antimoniate. Sixty parasitologically proven cases with 1-3 lesions were included and divided randomly into two equal groups; one group received 1 ml of meglumine antimonate intradermally every other day for 20 days, the other group received the ointment containing 15% parmomycin sulfate in urea twice daily for 20 days. The patients were clinically evaluated at 1 and 6 weeks after treatment was completed. The results of clinical evaluation at 1 week after treatment completed showed a cure rate of 18 out of 27 (66%) in the meglumine antimonate injected group and 20 out of 29 (68%) in the paromomycin sulfate treated group. The chi square test was used to compare the cure rate between the two groups and showed no significant difference (p = 0.85).     

Preparation and evaluation of niosomes containing autoclaved Leishmania major: a preliminary study

In this study, different positively charged niosomal formulations containing sorbitan esters, cholesterol and cetyl trimethyl ammonium bromide were prepared by film hydration method for the entrapment of autoclaved Leishmania major (ALM). Size distribution pattern and stability of niosomes were investigated by laser light scattering method and ALM encapsulation per cent was measured by the bicinchoninic acid method. Finally, the selected formulation was used for the induction of the immune response against cutaneous leishmaniasis in BALB/c mice. Size distribution curves of all the formulations followed a log-normal pattern and the mean volume diameter was in the range 7.57-15.80 μm. The mean volume diameters were significantly increased by adding Tween to Span formulations (p?相似文献   

Immunization against leishmaniasis by PLGA nanospheres encapsulated with autoclaved Leishmania major (ALM) and CpG-ODN

Various adjuvants and delivery systems have been evaluated for increasing the protective immune responses against leishmaniasis and mostly have been shown not to be effective enough. In this study, poly(d,l-lactide-co-glycolide) (PLGA) nanospheres as an antigen delivery system and CpG-ODN as an immunoadjuvant have been used for the first time to enhance the immune response against autoclaved Leishmania major (ALM). PLGA nanospheres were prepared by a double-emulsion (W/O/W) technique. Particulate characteristics were studied by scanning electron microscopy and particle size analysis. Mean diameter of ALM + CpG-ODN-loaded nanospheres was 300 ± 128 nm. BALB/c mice were immunized three times in 3-week intervals using ALM plus CpG-ODN-loaded nanospheres [(ALM + CpG-ODN)_PLGA], ALM encapsulated PLGA nanospheres [(ALM)_PLGA], (ALM)_PLGA + CpG, ALM + CpG, ALM alone, or phosphate buffer solution (PBS). The intensity of infection induced by L. major challenge was assessed by measuring size of footpad swelling. The strongest protection, showed by significantly (P < 0.05) smaller footpad, was observed in mice immunized with (ALM + CpG-ODN)_PLGA. The (ALM)_PLGA, (ALM)_PLGA + CpG, and ALM + CpG were also showed a significantly (P < 0.05) smaller footpad swelling compared to the groups received either PBS or ALM alone. The mice immunized with (ALM + CpG-ODN)_PLGA, (ALM)_PLGA + CpG, and ALM + CpG showed the highest IgG2a/IgG1 ratio, interferon-γ production, and lowest interleukin-4 production compared to the other groups. It is concluded that when both PLGA nanospheres and CpG-ODN adjuvants were used simultaneously, it induce stronger immune response and enhance protection rate against Leishmania infection.     

Cationic liposomes formulated with a novel whole Leishmania lysate (WLL) as a vaccine for leishmaniasis in murine model

Although there have been numerous attempts to develop a successful vaccine against leishmaniasis, based on the clinical trial in this field, no vaccine against Leishmania in routine way can be found for globally effective vaccination in human. Amongst, first generation vaccines consisting of parasite fractions or whole killed Leishmania showed more successful results in clinical trials. It seems that the main reason for the low efficacy of these vaccines is lack of a suitable adjuvant. In this study, a crude extract of detergent-solubilized L. major promastigotes as a novel developed antigen (whole Leishmania lysate (WLL)) was formulated in liposomal form. The cationic liposomes consisting of 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) were used to deliver WLL. Liposomes formulations containing different WLL concentrations (prepared from 10³, 10⁴, 10⁵, 10⁶ and 10⁷ parasites) were prepared and characterized for particle size, surface charge, proteins, DNA and phospholipids contents. Moreover, to explore the type of immune response generated and extend of immunization, in vivo and in vitro tests including evaluation of lesion development, parasite burden in the foot and spleen, Th1 and Th2 cytokine analysis, and titration of IgG isotypes before and after the challenge were used. The maximum immunization was provided by WLL06 as depicted by the reduction of footpad swelling andparasite load, increase in anti-Leishmania IgG2a production, though no significant difference was observed between mice which received WLL05 vs WLL06. While maximum immunization was seen in WLL06 group, most of the liposomal WLL formulations induced a mixed Th1/Th2 response. Hence, a more protective immune response is expected to be induced when an immune potentiator adjuvant such as CpG ODNs would be co-deliverd in WLL liposomal formulations.     

Liposomal SLA co-incorporated with PO CpG ODNs or PS CpG ODNs induce the same protection against the murine model of leishmaniasis

First generation Leishmania vaccines consisting of whole killed parasites with or without adjuvants have reached phase 3 trial and failed to show enough efficacy mainly due to the lack of an appropriate adjuvant. In this study, the nuclease-resistant phosphorothioate CpG oligodeoxynucleotides (PS CpG) or nuclease-sensitive phosphodiester CpG ODNs (PO CpG) were used as adjuvants to enhance immunogenicity and rate of protection against leishmaniasis. Due to the susceptibility of PO CpG to nuclease degradation, an efficient liposomal delivery system was developed to protect them from degradation. 1, 2-dioleoyl-3-trimethylammonium-propane (DOTAP) as a cationic lipid was used because of its unique adjuvanticity and electrostatic interaction with negatively charged CpG ODNs. To evaluate the role of liposomal formulation in protection rate and enhanced immune response, BALB/c mice were immunized subcutaneously with liposomal soluble Leishmania antigens (SLA) co-incorporated with PO CpG (Lip-SLA-PO CpG), Lip-SLA-PS CpG, SLA+PO CpG, SLA+PS CpG, SLA or buffer. As criteria for protection, footpad swelling at the site of challenge, parasite loads, the levels of IFN-γ and IL-4, and the IgG subtypes were evaluated. The groups of mice receiving Lip-SLA-PO CpG or Lip-SLA-PS CpG showed a high protection rate compared with the control groups. In addition, there was no significant difference in immune response generation between mice immunized with PS CpG and the group receiving PO CpG when incorporated into the liposomes. The results suggested that liposomal form of PO CpG might be used instead of PS CpG in future vaccine formulations as an efficient adjuvant.     

Gene Regulation of Pteridine Reductase 1 in Leishmania Promastigotes and Amastigotes Using a Full-Length Antisense Construct

Background

Pteridine metabolic pathway is unusual features of Leishmania, which is necessary for the growth of parasite. Leishmania has evolved a complex and versatile pteridine salvage network which has the ability of scavenging a wide area of the conjugated and unconjugated pteridines especially folate and biopterin. In this study, we focus on the inhibition of ptr1 gene expression.

Methods

L. major ptr1 gene was cloned into pcDNA3 and digested using KpnI and BamHI. The gene was subcloned so that antisense will transcribe and called pcDNA-rPTR. Leishmania major was cultured and late logarithmic-phase promastigotes were harvested. The promastigotes were divided into two groups. One group was transfected with 50 µg of pcDNA-rPTR, whereas the other group was transfected with pcDNA3. Transfected cells were cultured and plated onto semi-solid media. Mouse pritonean macrophages were transfected using pcDNA-rPTR–tansfected promastigotes. Western blotting was performed on mouse transfected pritonean macrophages and extracts from transfected promastigotes of L. major using a L. major ptr1 antibody raised in rabbits.

Results

The PTR1 protein was not expressed in pcDNA-rPTR– tansfected promastigotes and mouse macrophage transfected with pcDNA-rPTR– tansfected promastigotes.

Conclusion

This approach might be used to study the pteridine salvage pathway in Leishmania or to assess the possibility of using gene expression inhibition in the treatment of leishmaniasis.     

Imiquimod in combination with meglumine antimoniate for cutaneous leishmaniasis: a randomized assessor-blind controlled trial

OBJECTIVE: To determine the efficacy and safety of imiquimod in combination with meglumine antimoniate in treating cutaneous leishmaniasis. DESIGN: Prospective, randomized, assessor-blind, parallel-design, placebo-controlled trial. SETTING: Two primary care health clinics. PATIENTS: One hundred nineteen patients (59 patients in the imiquimod group and 60 in the placebo group) were included in the study. INTERVENTIONS: Patients were randomly assigned to receive a combined 4-week course of imiquimod or placebo with meglumine antimoniate treatment (20 mg/kg of pentavalent antimony daily for 2 weeks) in an endemic area of Leishmania tropica. MAIN OUTCOME MEASURES: The primary end point was clinical cure, defined as more than 75% reduction in the size of lesions compared with baseline at week 8. RESULTS: At the end of the 4-week treatment period, clinical cure was similar in both groups (11 patients [18.6%] in the imiquimod-treated group vs 18 patients [30.0%] in the placebo group) (P = .15). Four weeks after the end of treatment, 26 patients (44.1%) and 29 patients (48.3%) in the imiquimod-treated and placebo groups, respectively, were cured (P = .64). Pruritus and burning sensation were reported by 3 patients treated with imiquimod and by no patients treated with placebo. CONCLUSION: This study showed no beneficial effect of combining a 4-week course of treatment with 5% imiquimod cream and a standard course of treatment with meglumine antimoniate in patients with cutaneous leishmaniasis in an endemic area of L tropica. TRIAL REGISTRATION: isrctn.org Identifier:ISRCTN77659407 and Cochrane Skin Group Identifier: CSG Trial No. 32.     

PEGylation of cationic liposomes encapsulating soluble Leishmania antigens reduces the adjuvant efficacy of liposomes in murine model

Although there have been several attempts to develop a vaccine against leishmaniasis, no vaccine in human has been developed yet. Liposomes consisting of 1, 2‐dioleoyl‐3‐trimethylammonium‐propane (DOTAP) encapsulating soluble Leishmania antigens (SLA) enhance protective immunity of SLA against Leishmania major infection in mice. However, they immobilized at the injection site because of their positive charge. To overcome the problem, shielding the surface charge with polyethylene glycol (PEGylation) was chosen in this study. Liposomal SLA consisting different concentrations of PEG (1.9%‐15% mol) were prepared. BALB/c mice were immunized three times in 3 weeks intervals with different formulations. Lesion development and parasite burden in footpad and spleen were evaluated to specify the type of generated immune response and extent of protection. Th1/Th2 cytokine profiles and IgG isotypes were also analysed. The maximum protection was observed in mice immunized with Lip‐SLA or pLip‐SLA (1.9%) due to smaller footpad swelling, reduction in parasite load, an increase in IgG2a and IFN‐γ production. Our results showed that immunization of mice with a high level of PEG (>7.5%) did not improve protective immunity of liposomal SLA. The presence of PEG, particularly more than 3.75%, is not recommended for protection against leishmaniasis.