Drug repurposing for schistosomiasis: molecular docking and dynamics investigations.

Schistosomiasis is a neglected disease of considerable health importance in tropical and subtropical regions. Its treatment relies on the use of praziquantel or oxamniquine but there are reported cases of treatment failures due to resistance or tolerance. Again, derivatives of praziquantel and oxamniquine have not shown significant activities than their parent compounds. The study predicted approved drugs with possible antischistosomal activities. Four schistosomal drug targets were obtained from Protein Data Bank and six hundred and twelve (612) approved drugs including their isomers were selected based on their Molinspiration® bioscore similarities with reference compounds (praziquantel, oxamniquine, [(2S,3S,4S,5S,6S)-3,4,5-triacetyloxy-6-sulfanyloxan-2-yl] methyl acetate, [propylamino-3-hydroxy-buta-1,4-dionyl]-isoleucylproline). The selected drugs and drug targets were obtained and prepared for molecular docking simulations. The molecular docking simulations were performed using AutoDockvina®-1.1.2 after validation of docking protocols while molecular dynamics simulations were performed with GROMACS-4.5.5. The binding energies were calculated using MMPBSA (Molecular Mechanics Poisson-Boltzmann Surface Area). Tolmetin was predicted as potential antischistosomal drug with binding energies of -231.064 ± 18.550 and -338.636 ± 36.900 KJ/mol for sulfotransferase and thioredoxin glutathione reductase (TGR) respectively. Also diflunisal was predicted as potential antischistosomal drug with binding energies of -168.641 ± 20.370 and -290.117 ± 43.800 KJ/mol for sulfotransferase and TGR respectively. Non-covalent interactions and conformational changes were responsible for molecular recognitions and specificities and average bond measurement showed that carboxylic functional groups in diflunisal and tolmetin may interact covalently with -SH group of Cys159 in TGR. Confirmation of covalent interactions and in vitro validations are recommended.Communicated by Ramaswamy H. Sarma.

Drug Discovery and Target Identification against Schistosomiasis: A Reality Check on Progress and Future Prospects.

Schistosomiasis ranks among the most important infectious diseases, with over 200 million people currently being infected and > 280,000 deaths reported annually. Chemotherapeutic treatment has relied on one drug, praziquantel, for four decades, while other drugs, such as oxamniquine and metrifonate, are no longer preferred for clinical use due to their narrow spectrum of activity - these are only active against S. mansoni and S. haematobium, respectively. Despite being cheap, safe, and effective against all schistosome species, praziquantel is ineffective against immature worms, which may lead to reinfections and treatment failure in endemic areas; a situation that necessitates repeated administration besides other limitations. Therefore, novel drugs are urgently needed to overcome this situation. In this paper, an up to date review of drug targets identified and validated against schistosomiasis while also encompassing promising clinical and preclinical candidate drugs is presented. While there are considerable efforts aimed at identifying and validating drug targets, the pipeline for new antischistosomals is dry. Moreover, the majority of compounds evaluated preclinically are not really advanced because most of them were evaluated in very small preclinical species such as mice alone. Overall, it appears that although a lot of research is going on at discovery phases, unfortunately, it does not translate to advanced preclinical and clinical evaluation.

Molecular basis for hycanthone drug action in schistosome parasites.

Hycanthone (HYC) is a retired drug formerly used to treat schistosomiasis caused by infection from Schistosoma mansoni and S. haematobium. Resistance to HYC was first observed in S. mansoni laboratory strains and in patients in the 1970s and the use of this drug was subsequently discontinued with the substitution of praziquantel (PZQ) as the single antischistosomal drug in the worldwide formulary. In endemic regions, multiple organizations have partnered with the World Health Organization to deliver PZQ for morbidity control and prevention. While the monotherapy reduces the disease burden, additional drugs are needed to use in combination with PZQ to stay ahead of potential drug resistance. HYC will not be reintroduced into the schistosomiasis drug formulary as a combination drug because it was shown to have adverse properties including mutagenic, teratogenic and carcinogenic activities. Oxamniquine (OXA) was used to treat S. mansoni infection in Brazil during the brief period of HYC use, until the 1990s. Its antischistosomal efficacy has been shown to work through the same mechanism as HYC and it does not possess the undesirable properties linked to HYC. OXA demonstrates cross-resistance in Schistosoma strains with HYC resistance and both are prodrugs requiring metabolic activation in the worm to toxic sulfated forms. The target activating enzyme has been identified as a sulfotransferase enzyme and is currently used as the basis for a structure-guided drug design program. Here, we characterize the sulfotransferases from S. mansoni and S. haematobium in complexes with HYC to compare and contrast with OXA-bound sulfotransferase crystal structures. Although HYC is discontinued for antischistosomal treatment, it can serve as a resource for design of derivative compounds without contraindication.

Oxamniquine resistance alleles are widespread in Old World Schistosoma mansoni and predate drug deployment.

Do mutations required for adaptation occur de novo, or are they segregating within populations as standing genetic variation? This question is key to understanding adaptive change in nature, and has important practical consequences for the evolution of drug resistance. We provide evidence that alleles conferring resistance to oxamniquine (OXA), an antischistosomal drug, are widespread in natural parasite populations under minimal drug pressure and predate OXA deployment. OXA has been used since the 1970s to treat Schistosoma mansoni infections in the New World where S. mansoni established during the slave trade. Recessive loss-of-function mutations within a parasite sulfotransferase (SmSULT-OR) underlie resistance, and several verified resistance mutations, including a deletion (p.E142del), have been identified in the New World. Here we investigate sequence variation in SmSULT-OR in S. mansoni from the Old World, where OXA has seen minimal usage. We sequenced exomes of 204 S. mansoni parasites from West Africa, East Africa and the Middle East, and scored variants in SmSULT-OR and flanking regions. We identified 39 non-synonymous SNPs, 4 deletions, 1 duplication and 1 premature stop codon in the SmSULT-OR coding sequence, including one confirmed resistance deletion (p.E142del). We expressed recombinant proteins and used an in vitro OXA activation assay to functionally validate the OXA-resistance phenotype for four predicted OXA-resistance mutations. Three aspects of the data are of particular interest: (i) segregating OXA-resistance alleles are widespread in Old World populations (4.29-14.91% frequency), despite minimal OXA usage, (ii) two OXA-resistance mutations (p.W120R, p.N171IfsX28) are particularly common (>5%) in East African and Middle-Eastern populations, (iii) the p.E142del allele has identical flanking SNPs in both West Africa and Puerto Rico, suggesting that parasites bearing this allele colonized the New World during the slave trade and therefore predate OXA deployment. We conclude that standing variation for OXA resistance is widespread in S. mansoni.

Schistosomiasis: Drugs used and treatment strategies.

Neglected tropical diseases (NTDs) affect millions of people in different geographic regions, especially the poorest and most vulnerable. Currently NTDs are prevalent in 149 countries, seventeen of these neglected tropical parasitic diseases are classified as endemic. One of the most important of these diseases is schistosomiasis, also known as bilharzia, a disease caused by the genus Schistosoma. It presents several species, such as Schistosoma haematobium, Schistosoma japonicum and Schistosoma mansoni, the latter being responsible for parasitosis in Brazil. Contamination occurs through exposure to contaminated water in the endemic region. This parasitosis is characterized by being initially asymptomatic, but it is able to evolve into more severe clinical forms, potentially causing death. Globally, more than 200 million people are infected with one of three Schistosome species, including an estimated 40 million women of reproductive age. In Brazil, about 12 million children require preventive chemotherapy with anthelmintic. However, according to the World Health Organization (WHO), only about 15% of the at-risk children receive regular treatment. The lack of investment by the pharmaceutical industry for the development and/or improvement of new pharmaceutical forms, mainly aimed at the pediatric public, is a great challenge. Currently, the main forms of treatment used for schistosomiasis are praziquantel (PZQ) and oxaminiquine (OXA). PZQ is the drug of choice because it presents as a high-spectrum anthelmintic, used in the treatment of all known species of schistosomiasis and some species of cestodes and trematodes. OXA, however, is not active against the three Schistosome species. This work presents a literature review regarding schistosomiasis. It addresses points such as available treatments, the role of the pharmaceutical industry against neglected diseases, and perspectives for treatment.

Ectopic Schistosoma mansoni Eggs Inside a Lipoma.

Ectopic schistosomiasis is uncommon and tends to occur when the parasite's eggs or adult forms are located far from their normal site. This report presents the first described case of ectopic Schistosoma mansoni eggs inside a subcutaneous lipoma far from the tissues of this worm's life cycle and with no connection to either portal veins or any other vascular system. These eggs were found inside giant cells surrounded by inflammatory cells. In conclusion, in humans, ectopic S. mansoni eggs can be found far from the tissues of the described life cycle of this worm, with no connection to portal veins or other blood vessels used for their migration.

Efficient linkage mapping using exome capture and extreme QTL in schistosome parasites.

BACKGROUND: Identification of parasite genes that underlie traits such as drug resistance and host specificity is challenging using classical linkage mapping approaches. Extreme QTL (X-QTL) methods, originally developed by rodent malaria and yeast researchers, promise to increase the power and simplify logistics of linkage mapping in experimental crosses of schistosomes (or other helminth parasites), because many 1000s of progeny can be analysed, phenotyping is not required, and progeny pools rather than individuals are genotyped. We explored the utility of this method for mapping a drug resistance gene in the human parasitic fluke Schistosoma mansoni. RESULTS: We staged a genetic cross between oxamniquine sensitive and resistant parasites, then between two F1 progeny, to generate multiple F2 progeny. One group of F2s infecting hamsters was treated with oxamniquine, while a second group was left untreated. We used exome capture to reduce the size of the genome (from 363 Mb to 15 Mb) and exomes from pooled F2 progeny (treated males, untreated males, treated females, untreated females) and the two parent parasites were sequenced to high read depth (mean = 95-366×) and allele frequencies at 14,489 variants compared. We observed dramatic enrichment of alleles from the resistant parent in a small region of chromosome 6 in drug-treated male and female pools (combined analysis: Z = 11.07, p = 8.74 × 10(-29)). This region contains Smp_089320 a gene encoding a sulfotransferase recently implicated in oxamniquine resistance using classical linkage mapping methods. CONCLUSIONS: These results (a) demonstrate the utility of exome capture for generating reduced representation libraries in Schistosoma mansoni, and (b) provide proof-of-principle that X-QTL methods can be successfully applied to an important human helminth. The combination of these methods will simplify linkage analysis of biomedically or biologically important traits in this parasite.

Schistogram changes after administration of antischistosomal drugs in mice at the early phase of Schistosoma mansoni infection.

Mice infected with Schistosoma mansoni were treated with oxamniquine, praziquantel, artesunate at the pre-patent phase, aiming at observing schistogram alterations. Half of the animals were perfused five days post-treatment for counting and classification of immature worms, based on pre-established morphological criteria (schistogram); the remaining animals were evaluated 42 or 100 days after infection and perfusion of the portal-system was performed for collection and counting of adult worms and oogram. It was observed that oxamniquine and artesunate treatment administered at the pre-postural phase causes significant reduction in the number of immature and adult worms. However, there was little reduction with praziquantel when used at the dose of 400 mg/kg for treatments administered 14, 15, 21 or 23 days post-infection. Artesunate was responsible for significant alterations in development of young worms, as well as for a higher number of worms presenting intestinal damages. Immature adult worms were detected in mice treated with artesunate or oxamniquine at the pre-patent phase of infection and recovered by perfusion 100 days after infection. Schistogram proved to be a very useful tool for experimental evaluation of the activity of antischistosomal drugs and a good model to identify the most sensitive stages to drugs.

Schistogram changes after administration of antischistosomal drugs in mice at the early phase of Schistosoma mansoni infection

Mice infected with Schistosoma mansoni were treated with oxamniquine, praziquantel, artesunate at the pre-patent phase, aiming at observing schistogram alterations. Half of the animals were perfused five days post-treatment for counting and classification of immature worms, based on pre-established morphological criteria (schistogram); the remaining animals were evaluated 42 or 100 days after infection and perfusion of the portal-system was performed for collection and counting of adult worms and oogram. It was observed that oxamniquine and artesunate treatment administered at the pre-postural phase causes significant reduction in the number of immature and adult worms. However, there was little reduction with praziquantel when used at the dose of 400 mg/kg for treatments administered 14, 15, 21 or 23 days post-infection. Artesunate was responsible for significant alterations in development of young worms, as well as for a higher number of worms presenting intestinal damages. Immature adult worms were detected in mice treated with artesunate or oxamniquine at the pre-patent phase of infection and recovered by perfusion 100 days after infection. Schistogram proved to be a very useful tool for experimental evaluation of the activity of antischistosomal drugs and a good model to identify the most sensitive stages to drugs.

Drugs for treating Schistosoma mansoni infection.

BACKGROUND: Schistosoma mansoni is a parasitic infection common in the tropics and sub-tropics. Chronic and advanced disease includes abdominal pain, diarrhoea, blood in the stool, liver cirrhosis, portal hypertension, and premature death. OBJECTIVES: To evaluate the effects of antischistosomal drugs, used alone or in combination, for treating S. mansoni infection. SEARCH METHODS: We searched MEDLINE, EMBASE and LILACS from inception to October 2012, with no language restrictions. We also searched the Cochrane Infectious Diseases Group Specialized Register, CENTRAL (The Cochrane Library 2012) and mRCT. The reference lists of articles were reviewed and experts were contacted for unpublished studies. SELECTION CRITERIA: Randomized controlled trials of antischistosomal drugs, used alone or in combination, versus placebo, different antischistosomal drugs, or different doses of the same antischistosomal drug for treating S. mansoni infection. DATA COLLECTION AND ANALYSIS: One author extracted data and assessed eligibility and risk of bias in the included studies, which were independently checked by a second author. We combined dichotomous outcomes using risk ratio (RR) and continuous data weighted mean difference (WMD); we presented both with 95% confidence intervals (CI). We assessed the quality of evidence using the GRADE approach. MAIN RESULTS: Fifty-two trials enrolling 10,269 participants were included. The evidence was of moderate or low quality due to the trial methods and small numbers of included participants.Praziquantel: Compared to placebo, praziquantel 40 mg/kg probably reduces parasitological treatment failure at one month post-treatment (RR 3.13, 95% CI 1.03 to 9.53, two trials, 414 participants, moderate quality evidence). Compared to this standard dose, lower doses may be inferior (30 mg/kg: RR 1.52, 95% CI 1.15 to 2.01, three trials, 521 participants, low quality evidence; 20 mg/kg: RR 2.23, 95% CI 1.64 to 3.02, two trials, 341 participants, low quality evidence); and higher doses, up to 60 mg/kg, do not appear to show any advantage (four trials, 783 participants, moderate quality evidence).The absolute parasitological cure rate at one month with praziquantel 40 mg/kg varied substantially across studies, ranging from 52% in Senegal in 1993 to 92% in Brazil in 2006/2007. Oxamniquine: Compared to placebo, oxamniquine 40 mg/kg probably reduces parasitological treatment failure at three months (RR 8.74, 95% CI 3.74 to 20.43, two trials, 82 participants, moderate quality evidence). Lower doses than 40 mg/kg may be inferior at one month (30 mg/kg: RR 1.78, 95% CI 1.15 to 2.75, four trials, 268 participants, low quality evidence; 20 mg/kg: RR 3.78, 95% CI 2.05 to 6.99, two trials, 190 participants, low quality evidence), and higher doses, such as 60 mg/kg, do not show a consistent benefit (four trials, 317 participants, low quality evidence).These trials are now over 20 years old and only limited information was provided on the study designs and methods. Praziquantel versus oxamniquine: Only one small study directly compared praziquantel 40 mg/kg with oxamniquine 40 mg/kg and we are uncertain which treatment is more effective in reducing parasitological failure (one trial, 33 participants, very low quality evidence). A further 10 trials compared oxamniquine at 20, 30 and 60 mg/kg with praziquantel 40 mg/kg and did not show any marked differences in failure rate or percent egg reduction.Combination treatments: We are uncertain whether combining praziquantel with artesunate reduces failures compared to praziquantel alone at one month (one trial, 75 participants, very low quality evidence).Two trials also compared combinations of praziquantel and oxamniquine in different doses, but did not find statistically significant differences in failure (two trials, 87 participants). Other outcomes and analyses: In trials reporting clinical improvement evaluating lower doses (20 mg/kg and 30 mg/kg) against the standard 40 mg/kg for both praziquantel or oxamniquine, no dose effect was demonstrable in resolving abdominal pain, diarrhoea, blood in stool, hepatomegaly, and splenomegaly (follow up at one, three, six, 12, and 24 months; three trials, 655 participants).Adverse events were not well-reported but were mostly described as minor and transient.In an additional analysis of treatment failure in the treatment arm of individual studies stratified by age, failure rates with 40 mg/kg of both praziquantel and oxamniquine were higher in children. AUTHORS' CONCLUSIONS: Praziquantel 40 mg/kg as the standard treatment for S. mansoni infection is consistent with the evidence. Oxamniquine, a largely discarded alternative, also appears effective.Further research will help find the optimal dosing regimen of both these drugs in children.Combination therapy, ideally with drugs with unrelated mechanisms of action and targeting the different developmental stages of the schistosomes in the human host should be pursued as an area for future research.

Schistosoma mansoni: avaliação da fibrose hepática em camundongos submetidos quimioterapia e reinfectados / Schistosoma mansoni: assessment of hepatic fibrosis in mice undergoing chemotherapy and reinfected

A esquistossomose mansônica é uma doença parasitária tropical. Causadas por helmintos do gênero Schistosoma. Com a intenção de conter a doença, diversos institutos e organizações vêm desenvolvendo medidas de controle para tratar indivíduos infectados e evitar a ocorrência de novas infecções. Estratégias de administração de medicamentos em massa são eficazes na cura da doença, entretanto o tratamento com drogas anti-helmínticas não previnem a possibilidade da ocorrência de reinfecções. Diante desta questão, neste trabalho propusemo-nos a analisar a cinética da fibrose hepática em camundongos esquistossomóticos tratados e submetidos à reinfecção. Para alcançar este objetivo, 70 camundongos Swiss foram infectados com 50 cercárias de S.mansoni, posteriormente tratados com Oxamniquine ou Praziquantel e reinfectados quatro meses após tratamento. Os fígados destes animais foram submetidos a técnicas de imunohistoquímica e imunofluorescência e microscopia eletrônica de transmissão para avaliação da expressão e participação de componentes envolvidos no processo fibrogênico. Para verificar os índices de colágeno entre os grupos utilizou-se a análise morfométrica. A análise histológica revelou que camundongos esquistossomóticos submetidos à quimioterapia específica desenvolveram altos índices de fibrose durante a reinfecção. A imunomarcação para alfa actina de músculo liso (α-SMA) revelou que grande parte do parênquima hepático dos animais tratados e reinfectados exibiam células com perfil miofibloblástico. A imunofluorescência demonstrou que o padrão de marcação para laminina estava alterado em animais com esquistossomose. A análise morfométrica revelou que reinfecção destes animais ocasionou uma intensa deposição de fibras colágenas no parênquima hepático. Os dados obtidos demonstraram que a reinfecção em animais previamente tratados, foi capaz de induzir uma resposta fibrótica semelhante a encontrada nos animais com infecção primária.

Schistosoma mansoni: a rare cause of tubal infection.

S. haematobium is an important cause of urinary schistosomiasis, and symptomatic female genital infection is a common gynecological finding in areas where S. haematobium is prevalent. On the other hand, genital manifestations of intestinal schistosomas as S. mansoni are not frequent or are misdiagnosed. A case of a 40-year-old woman with abnormal uterine bleeding and asymptomatic tubal infection by S. mansoni identified in histological examination is presented.

Antibody reactivity against potato apyrase, a protein that shares epitopes with Schistosoma mansoni ATP diphosphohydrolase isoforms, in acute and chronically infected mice, after chemotherapy and reinfection.

Schistosoma mansoni ATP diphosphohydrolase isoforms and potato apyrase share conserved epitopes. By enzyme-linked immunosorbent assays, elevated levels of IgM, IgG2a and IgG1 antibody reactivity against potato apyrase were observed in S. mansoni-infected BALB/c mice during the acute phase of infection, while only IgM and IgG1 antibody reactivity levels maintained elevated during the chronic phase of infection. Antibody reactivity against potato apyrase was monitored over an 11-month period in chronically-infected mice treated with oxamniquine. Eleven months later, the level of seropositive IgM decreased significantly (approximately 30%) compared to the level found in untreated, infected mice. The level of seropositive IgG1 decreased significantly four months after treatment (MAT) (61%) and remained at this level even after 11 months. The IgG2a reactivity against potato apyrase, although unchanged during chronic phase to 11 MAT, appeared elevated again in re-infected mice suggesting a response similar to that found during the acute phase. BALB/c mouse polyclonal anti-potato apyrase IgG reacted with soluble egg antigens probably due to the recognition of parasite ATP diphosphohydrolase. This study, for the first time, showed that the IgG2a antibody from S. mansoni-infected BALB mice cross-reacts with potato apyrase and the level of IgG2a in infected mice differentiates disease phases. The results also suggest that different conserved-epitopes contribute to the immune response in schistosomiasis.

Specific schistosomiasis treatment as a strategy for disease control.

The great hope for schistosomiasis treatment began with the development of oxamniquine and praziquantel. These drugs can be administered orally in a single dose and have a high curative power with minor side effects. In this study, we carried out a field experiment involving a population of 3,782 people. The population was examined at four localities in Minas Gerais within the valleys of the Doce and Jequitinhonha Rivers. In this cohort, there were 1,790 patients infected with Schistosoma mansoni (47.3%) and we showed that only 1,403 (78.4%) could be treated with oxamniquine in a single dose of 12.5-20 mg/kg orally. The other 387 (21.6%) were not treated during the first stage because of contraindications (pregnancy or impeditive diseases), absences or refusals. It was observed that, on average, 8.8-17% of the infected patients continued to excrete S. mansoni eggs at the end of the 2nd month after treatment and 30-32% of the cohort was infected by the end of the 24th month. In one of the areas that we followed-up for a total of 30 years, the prevalence of the infection with S. mansoni fell from 60.8-19.3% and the hepatosplenic form of the disease dropped from 5.8-1.3%. We conclude that specific treatment of schistosomiasis reduces the prevalence of infection in the short-term and the morbidity due to schistosomiasis in medium to long-term time frames, but does not help to control disease transmission.

Schistosoma mansoni: a rare cause of tubal infection

S. haematobium is an important cause of urinary schistosomiasis, and symptomatic female genital infection is a common gynecological finding in areas where S. haematobium is prevalent. On the other hand, genital manifestations of intestinal schistosomas as S. mansoni are not frequent or are misdiagnosed. A case of a 40-year-old woman with abnormal uterine bleeding and asymptomatic tubal infection by S. mansoni identified in histological examination is presented.

Schistosomiasis mansoni of the bladder simulating bladder cancer: a case report.

The relationship between bladder tumors and Schistosoma haematobium is well known, but only sporadic cases of bladder infection due to Schistosoma mansoni have been reported. In this case, a 48-year-old woman with macroscopic hematuria, dysuria and a palpable abdominal mass was investigated. Ultrasound showed a large exophytic mass in the bladder. Transurethral resection of the bladder revealed viable eggs of Schistosoma mansoni. The patient was treated clinically with oxamniquine and surgery was performed to resect the large mass. This case shows that schistosomiasis Mansoni in the bladder can simulate bladder cancer.

Schistosomiasis mansoni of the bladder simulating bladder cancer: a case report / Esquistossomose mansônica simulando câncer de bexiga: relato de caso

The relationship between bladder tumors and Schistosoma haematobium is well known, but only sporadic cases of bladder infection due to Schistosoma mansoni have been reported. In this case, a 48-year-old woman with macroscopic hematuria, dysuria and a palpable abdominal mass was investigated. Ultrasound showed a large exophytic mass in the bladder. Transurethral resection of the bladder revealed viable eggs of Schistosoma mansoni. The patient was treated clinically with oxamniquine and surgery was performed to resect the large mass. This case shows that schistosomiasis Mansoni in the bladder can simulate bladder cancer.

É bem conhecida a relação entre tumor vesical e Schistosoma haematobium, porém somente casos esporádicos de infecção vesical por Schistosoma mansoni foram relatados. Neste caso, uma mulher de 48 anos com hematúria macroscópica, disúria e massa abdominal palpável foi investigada, ultra-sonografia mostrou uma grande massa exofítica na bexiga. A ressecção transuretral de bexiga evidenciou ovos viáveis de Schistosoma mansoni. A paciente foi tratada clinicamente com oxaminiquine e uma cirurgia foi realizada para ressecar a grande massa. Este caso mostra que a esquistossomose mansônica vesical pode simular um câncer vesical.

Similar cellular responses after treatment with either praziquantel or oxamniquine in Schistosoma mansoni infection.

The effect of treatment with either oxamniquine or praziquantel on S.mansoni specific IFN-gamma, IL-4, IL-5 and IL-10 was compared on PBMC which were collected pretreatment, 6 and 18 weeks post treatment. Using sandwich ELISA on the supernatants harvested from the PBMC stimulation by crude S. mansoni SEA and SWAP antigens after 5 days the levels of PBMC proliferation and cytokine production were similar according to treatment with either praziquantel or oxamniquine. Before treatment, infected groups showed low ratios, of IL-4:IFN-gamma, IL-5:IFNgamma and IL-10:IFN-gamma, indicating that IFN-gamma was high in the infected individuals. The general increase in immuno-modulation was observed post-treatment with elevated immune reactivity and cytokine production in both treatment groups. Treatment induced significant increases in levels of IL-4 (p < 0.05), IL-5 (p < 0.0001) and IL-10 (p < 0.05) cytokines 6 and 18 weeks after treatment. There were no significant differences in the increase in IL-4, IL-5 and IL-10 between children treated with praziquantel or oxamniquine. Pre-treatment IFN-gamma and IL-5 levels were positively correlated with infection (p < 0.001), while post treatment IL-4 cytokine levels were negatively correlated with baseline infection status (p < 0.001). The results suggest that treatment-induced immune responses are similar for both common anti-schistosome drugs praziquantel or oxamniquine having similar and immunizing effect.

Oxamniquine, praziquantel and lovastatin association in the experimental Schistosomiasis mansoni.

The activity of lovastatin associated with oxamniquine or praziquantel against schistosomiasis mansoni was evaluated in mice infected with Schistosoma mansoni. Forty days after infection, mice were treated with lovastatin, 400 mg/kg for five consecutive days by oral route, and on the last day of this sequence with 50 mg/kg oxamniquine or with 200 mg/kg praziquantel, both by oral route, single dose. Fifteen days later, the animals were perfused in parallel with an untreated control group. Studies were carried out in vitro, using lovastatin in culture medium containing S. mansoni worms proceeding from experimentally infected mice. In the in vivo trials, the association of lovastatin with oxamniquine or praziquantel did not show any additive action, but there were oogram changes when lovastatin was associated with oxamniquine. In vitro lovastatin was able to interrupt the maturation of S. mansoni eggs, which remained at the 1st or 2nd stages, depending on the dose used. The total number of morphologically dead eggs found in culture of worms exposed to 2 microg/ml or 4 microg/ml concentrations of lovastatin was significantly higher than the number of viable eggs. Using the probe Hoescht 33258 it was observed that 70% of the eggs considered morphologically viable in the treated groups (against 16% in the control group) were labeled, indicating that the majority of the viable eggs had membrane permeability increased due to lovastatin action.