Keywords
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            | Schistosoma mansoni, Selenium nano-particles, Liver, Mice. | 
        
        
            
            Introduction
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            | Developing countries such as “Africa, South America and       Asia” are suffering from morbidity and mortality due to       schistosomiasis. The main agent of human schistosomiasis is       Schistosoma mansoni [1]. Predominantly, eggs of Schistosoma       mansoni are deposited in the liver and intestines which       resulting in parasitic disease [2]. In addition; Mahmoud et al.       [3] reported that the clinical symptoms include       hepatosplenomegaly, liver fibrosis, portal hypertension, and       liver cirrhosis. Acute symptoms of schistosomiasis include       fever, diarrhea, abdominal pain, weight loss, and eosinophilia       [4]. | 
        
        
            | Chang et al., [5] reported that eggs are transported to the liver       by portal circulation. Acute schistosomiasis is associated with       heavy primary infections and with the initiation of egg       production [4]. In the portal venous system eggs are deposited       while eggs are trapped in the peri-sinusoidal spaces of the liver,       thus causing periportal granulomatous inflammation and the       deposition of scar tissue around the eggs trapped inside the       liver [6]. Granulomas are formed of inflammatory cells       “eosinophils, macrophages, and lymphocytes” [7,8]. | 
        
        
            | Current treatment of schistosomiasis depends on praziquantel       (PZQ), which was developed in the late 1970s [9]. PZQ has       been widely used as an effective means to control       schistosomiasis. However, PZQ does not treat early infection       or prevent reinfection [10]. In addition, available evidence       indicates the appearance of PZQ resistance by schistosomes       [11,12,13,14]. | 
        
        
            | Heretofore controlling schistosomiasis, there is an urgent       necessity to discover a new effective drug. According to       National Science Foundation of USA, nanotechnology deals       with controlling or restructuring of the material dimension       more or less between 1 and 100 nm. For various reasons       related to their small size, e.g., better solubility, absorption and       uptake, nanoparticle-based medicines can get across cell       membranes and reach specific targets more easily than bulk       form agents [15]. | 
        
        
            | The field encompasses nanomedicine, which strives to utilize       nanotechnology to improve health care [16]. Various       nanoparticles have applications for diagnosis and treatment       [17]. Armstead and Li [18] recently summarized the range of       intracellular infectious diseases that nanomedicines may be       more effective in treating than conventional bulk form drugs,       such diseases include leismaniasis and malaria [19,20]. | 
        
        
            | Nano-elemental selenium (Se) has attracted wide spread       attention due to its high bioavailability and low toxicity       because nanometer particulates exhibit novel characteristics,       such as great specific surface area, high surface activity, and a       lot of surface active centers, high catalytic efficiency and       strong adsorbing ability and the character of low toxicity of       routine Se0 [21]. | 
        
        
            | Science the nano-elemental selenium (Se) has high       bioavailability, low toxicity and nanometer particulates; it has       attracted wide spread attention. Moreover, it showed new       features, such as great specific surface area, high surface       activity, high catalytic efficiency and strong adsorbing ability       and the character of low toxicity of routine Se0 [22]. | 
        
        
            | Many investigations have shown that Se in nano-form has       novel in vitro and in vivo antioxidant properties, which acts       through the activation of seleno-proteins [23]. | 
        
        
            | So far, there is not any information concerning Se       nanoparticles role in treatment of schistosome infected mice,       thus the aim of this paper is to investigate the anti-schistosomal       effect of Se nanoparticles on liver of infected mice. | 
        
        
            
            Materials and Methods
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            Animals
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            | Male Swiss albino mice weighing 20 ± 2 g were obtained from       the Experimental Animal Research Unit of the Schistosome Biological Supply Program at Theodor Bilharz   Research       Institute (TBRI), Al-Giza, Egypt and fed a standard diet and       water ad libitum. All experimental protocols were approved by       the legal and ethical guidelines of the Medical Ethics       Committee of TBRI, Giza, Egypt (Approval No. 4018/2011). | 
        
        
            
            Selenium nanoparticles
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            | Selenium nanoparticles (50-100 nm particle size) were       obtained from Nano-tech Lab in 6 October City, Egypt, as a       sterilized solution, as they were dispersed in phosphatebuffered       saline (PBS) and ready for use. In brief, a simple wet       chemical method has been developed to synthesize selenium       nanoparticles, by the reaction of sodium selenosulphate       precursor with deferent organic acids in aqueous medium,       under ambient conditions. Polyvinyl alcohol has been used to       stabilize the selenium nanoparticles. The synthesized       nanoparticles can be separated from its sol by using a highspeed       centrifuge and can be re-dispersed in aqueous medium       with a sonicator [24]. | 
        
        
            | Transmission electron microscope (TEM) was used for       characterization of nanoparticles (shape and size)       (Figure1).TEM were performed on JEOL JEM-2100 high       resolution TEM at an accelerating voltage of 200 kV,       respectively to characterize the size and shape of Se       nanoparticles. | 
        
        
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            Mice infection
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            | Mice were injected subcutaneously by 100 ± 10 S. mansoni       cercariae per mouse according to Oliver and Stirewalt [25].       The procedures of cercaria injection were done in Schistosome Biological Supply Center at Theodor Bilharz   ResearchInstitute,       Imbaba, Giza, Egypt. | 
        
        
            
            Experimental design
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            | Forty eight mice were divided into four groups (12 mice/       group), as follows: Group I normal, non-infected control group       received vehicle (0.5 ml/mice PBS by intrapretoneal (i.p)       injection for 7 consecutive days this group was injected b.       Groups II, III and IV were infected with S. mansoni cercariae       (100 ± 10). On day 46 post infection (pi) with S. mansoni, the       animals of group III were i.p injected 0.5 mg/kg SeNPs       dispersed in 0.5 ml PBS; for 7 consecutive days [26]. Infected       animals of group IV were orally administered 0.5 ml of PZQ       (600 mg/kg body weight) on day 46 pi at an interval of 24 h for       2 days. | 
        
        
            
            Egg count in infected hepatic tissue
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            | According to Pelligrino et al. [27]; the eggs in the hepatic       tissue of infected mice were counted. Concisely, 0.1 g of liver       was divided into 4 fragments; each one was crushed between a       slide and a cover slip. The slides were examined by light       microscope. | 
        
        
            
            Liver histopathology
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            | After animal dissection; mice hepatic tissue samples from each       of the groups were immediately fixed in 10% neutral buffered       formalin, then dehydrated and processed for paraffin       sectioning. Sections were then deparaffinised and stained with       hematoxylin and eosin. In addition; the diameter of tissue       granuloma was determined by measuring the mean diameter       (µm) for 30 granulomas were chosen from different sections       and different mice in each group. | 
        
        
            
            Biochemical analysis
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            | Glutathione level | 
        
        
            | By using Ellman’s reagent glutathione (GSH) level was       determined in the hepatic homogenates. This method is based on the reduction of Ellman’s reagent (5,5'   dithiobis (2-       nitrobenzoic acid) with GSH to produce a yellow compound.       The chromogen is directly proportional to the GSH       concentration and its absorbance was measured at 405 nm [28]. | 
        
        
            
            Nitrite/nitrate level
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            | According to the method of Green et al. [29]; the level of       nitrite/nitrate was determined; where, nitrous acid diazotize       sulfanilamide was formed in an acid medium and in the       presence of nitrite. Then nitrous acid diazotize sulfanilamide is       coupled with N-(1-naphthyl) ethylene diamine forming Azo       dye (a bright reddish-purple color) and it can be measured at       540 nm. | 
        
        
            
            Malondialdehyde level
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            | In liver homogenate malondialdehyde (MDA) level was       determined by using trichloroacetic acid (1 ml;10%) and of       thiobarbituric acid (1 ml;0.67%).In a boiling water bath; the       mixture was heated for 30 min. Thiobarbituric acid-reactive       substances were measured at 535 nm [30]. | 
        
        
            
            Statistical analysis
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            | The statistical comparisons among the groups were carried out       by using one-way ANOVA (Duncan’s test); (SPSS version       17.0). P<0.05 was considered as significant for all statistical       analysis in this study. | 
        
        
            
            Results
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            | From the histological view; schistosomiasis resulted in a       significant destructive lesions and distorted architecture of       hepatic tissue. Distinct granulomatous inflammation and       eosinophilic infiltration were noticed. In addition, S. mansoni       induced parenchyma disorganization, cell vacuolization and       liver necrosis as compared to non-infected group. Furthermore,       treatment with SeNPs revealed improvement in the histological       picture versus infected group (Figure 2). | 
        
        
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            | In the same manner, SeNPs treatment (0.5 mg/kg b.wt.) for 7       successive days reduced the number of ova in hepatic tissue of       infected mice significantly. Moreover, the granuloma size       (granuloma diameter) recorded a significant reduction (400 ±       31 µm) and (370 ± 29 µm) as a result of SeNPs and PZQ       injection, respectively versus schistosome-infected group (750       ± 55 µm) as shown in figure 3. | 
        
        
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            | The data presented in figure 4, revealed that the treatment of       schistosomiasis by SeNPs and PZQ induced a significant       reduction in eggs count in liver as compared to infected mice. | 
        
        
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            | Hepatic GSH level showed a significant reduction as a result of       Schistosomiasis mansoni. On contrary, the infection induced a       significant increment in both levels of nitrite/nitrate and MDA       as compared to non-infected values. On the other hand, SeNPs       treatment to the schistosome infected mice increased hepatic       GSH level significantly and reduced nitrite/nitrate and MDA       levels significantly versus infected group (Table1). | 
        
        
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            Discussion
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            | Ferrari et al. [31] cleared that in Schistosomiasis mansoni;       there is a marked correlation between worm burden and       disease severity in endemic areas. Moreover, severe       hepatosplenic forms were developed in approximately 4% of       untreated parasitized people. | 
        
        
            | Ferrari [32] studied the medical applications of       nanotechnology and concluded that while the risks are very       small, the potential benefits are huge in comparison. As a       consequence; in toxoplasmosis an alternative treatment       involved gold nanospheres. In addition, several nano sized       delivery systems have already proved their effectiveness in       animal models for the treatment and prophylaxis of malaria       [33]. Likewise, the use of nanotechnology for treatment of       leishmaniasis showed promising results and thus could be the pavement for curing this disease [34]. In   addition, Soflaei et al.       [35] revealed that selenium NPs and SeO2 have dosedependent       anti-leishmanial activities. Also, selenium NPs have       more anti-leishmanial activities with less cytotoxic effects than       SeO2. | 
        
        
            | The liver pathology of S. mansoni revealed a significant       distorted architecture and altered liver parenchyma. As well as,       the parasite infection caused granulomatous inflammatory       response; our histological findings go hand in hand with that of       Amer et al. [36]; Kadry et al. [37] and Dkhil [38]. | 
        
        
            | Granulomas were remarkable by concentric fibrosis and many       fibroblasts encircled the trapped eggs [36,37]. Moreover; Dkhil       [38] reported that infection with S. mansoni caused a severe       hepatic granulomatous inflammatory response which appears       in form of inflammatory cellular infiltration, cytoplasmic vacuolation and degeneration of hepatocytes. The   presence of       huge number of granulomas resulted in disorganization of the       hepatic strands and lobular structure where granulomas are       surrounded by a cuff of aggregated lymphocytes, epitheloid       cells, eosinophils and collagenous fibres. Also, the hepatic       sinusoids were dilated and apparently contained more Kupffer       cells. Meanwhile, our treatment with SeNPs improved all the       histological disturbances of liver of infected mice. | 
        
        
            | From the present results and previous studies; Schistosma       parasite induced a marked hepatic oxidative stress in       schistoseme-infected mice [36,37,38,39]. Amer et al. [36] and       Dkhil [38] deduced that S. mansoni altered the levels of free       radicals and enzymatic/non-enzymatic antioxidands       significantly. In the same manner, Fahmy et al. [39] reported       that schistosome infected mice elevated the level of MDA,       while decreased the GSH level and catalase activity       significantly in hepatic tissue. A significant elevation was       noticed in MDA and nitrite/nitrate levels, meanwhile; a       significant reduction was tabulated in an antioxidant markers       (GSH, glutathione reductase, catalase, thioredoxine reductase)       of infected liver [37]. | 
        
        
            | SeNPs injection (0.5 mg/kg b.wt.) increased GSH level on       contrary; it reduced the levels of nitrite/nitrate and MDA as       compared to infected mice. Previous studies revealed that Se at       nano-size can serve as antioxidant [40,41]; with lower toxic       effects than Se [41,42,43]. | 
        
        
            | From our results we can conclude that the SeNPs (0.5 mg/kg       body weight) injection for 7 sequent days caused ameliorating       effects of hepatic disturbances, histopathology and oxidative       stress. Ultimately, SeNPs have anti-schistosomal activities in       hepatic tissue of schistosome infected mice. | 
        
        
            
            Conflict of interest
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            | The authors declare that they have no conflict of interest. | 
        
        
            
            Acknowledgement
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            | The authors would like to extend their sincere appreciation to       the Deanship of Scientific Research at King Saud University       for its funding this research group No (RG-198). | 
        
        
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