Search

Background Schistosomiasis is a debilitating and neglected tropical disease for which praziquantel (PZQ) remains the first-choice drug for treatment and control of the disease. In our previous studies, we found that the patented compound DW-3-15 (patent no. ZL201110142538.2) displayed significant and stabilized antiparasitic activity through a mechanism that might be distinct from PZQ. Here, we investigated the antischistosomal efficacy of PZQ combined with DW-3-15 against schistosomula and adult worms of Schistosoma japonicum in vitro and in vivo, to verify whether there was a synergistic effect of the two compounds. Methods The antischistosomal efficacy of PZQ combined with DW-3-15 in comparison with an untreated control and monotherapy group against schistosomula and adult worms was assessed both in vitro and in vivo. Parasitological studies, scanning electron microscopy, combination index, and histopathological analysis were used for the assessment. Results The results showed significantly reduced viability of schistosomes, achieving 100% viability reduction for juveniles and males by combination chemotherapy using PZQ together with DW-3-15 in vitro. The combination index was 0.28, 0.27, and 0.53 at the higher concentration of PZQ combined with DW-3-15 against juveniles, males, and females, respectively, indicating that the two compounds display strong synergism. Scanning electron microscopy observations also demonstrated that the compound combination induced more severe and extensive alterations to the tegument and subtegument of S. japonicum than those with each compound alone. In vivo, compared with the single-compound-treated group, the group treated with the higher-dose combination demonstrated the best schistosomicidal efficacy, with significantly reduced worm burden, egg burden, and granuloma count and area, which was evident against schistosomula and adult worms. Conclusions Our study provides a potential novel chemotherapy for schistosomiasis caused by S. japonicum. It would improve the antischistosomal effect on schistosomula and adult worms of S. japonicum, and decrease individual dosages. Graphical Abstract

Background This study aims to understand whether there is a seasonal change in the internet search interest for Toxoplasma by using the data derived from Google Trends (GT). Methods The present study searched for the relative search volume (RSV) for the search term ‘Toxoplasma’ in GT within six major English-speaking countries (Australia, New Zealand [Southern Hemisphere] and Canada, Ireland, the UK and the USA [Northern Hemisphere] from 1 January 2004 to 31 December 2019, utilizing the category of ‘health’. Data regarding the RSV of Toxoplasma was obtained and further statistical analysis was performed in R software using the ‘season’ package. Results There were significantly seasonal patterns for the RSV of the search term ‘Toxoplasma’ in five countries (all p Conclusions Overall, our study revealed the seasonal variation for Toxoplasma in using internet search data from GT, providing additional evidence on seasonal patterns in Toxoplasma.

Background Th1, Th2, Th17, Treg and Tfh cells play important roles in schistosomiasis. Th9 cells secrete IL-9 as a signature cytokine and contribute to several classes of inflammatory disease. However, the effects of Th9 cells in schistosomiasis are unknown. We aimed to explore the dynamic changes and potential roles of Th9 cells in the pathogenesis of hepatic egg granulomatous inflammation in mice infected with Schistosoma japonicum. Methods Twenty mice with S. japonicum infection and five normal controls (NC) were used as models. The average areas of egg granulomas were estimated by hematoxylin-eosin (H & E) staining. Hepatic IL-9 and transcription factor PU.1 levels were detected by immunohistochemistry. Flow cytometry techniques were used to analyze the proportions of Th9 cells. With the help of ELISA, serum levels of IL-9 were examined. Results The egg granulomas began to form from four weeks after infection and continued to develop. In parallel with the development of egg granulomas, the hepatic levels of IL-9 and PU.1 increased very slowly during the first four weeks post-infection and increased rapidly thereafter. Moreover, the proportions of splenic Th9 cells and levels of serum IL-9 had similar developmental trends with the egg granulomas. Conclusion The proliferation of Th9 cells and levels of IL-9 were significantly higher in S. japonicum-infected mice compared to NC. In addition, dynamic changes of Th9 and IL-9 were synchronous with the developmental trend of hepatic egg granulomatous inflammation, suggesting that Th9 cells might be a new subset in the pathogenesis of schistosomiasis.

BackgroundHumoral immune responses play an important role in mediating liver granulomatous inflammation and fibrosis in schistosomiasis. Follicular helper T (Tfh) cells have a central role in mediating humoral immune responses. Generation of Tfh cells depends on inducible T cell costimulator (ICOS) signaling, but the underlying molecular mechanisms are incompletely understood in pathogenesis of schistosomiasis.Methodology/Principal FindingsWe used a strain of ICOS-transgenic (Tg) mice to test the degrees of liver granulomatous inflammation and fibrosis, the frequency of splenic Tfh cells and soluble egg antigen-specific cytokine responses longitudinally in mice following Schistosoma japonicum (S. japonicum) infection. In comparison with that in wide-type (WT) mice, significantly severer liver granulomatous inflammation and fibrosis and higher mortality were observed in ICOS-Tg mice. Significantly higher frequency of splenic Tfh cells was accompanied by significantly higher levels of Bcl-6 and CXCR5 expression in the livers of ICOS-Tg mice. Furthermore, significantly higher levels of SEA-specific IL-4, IL-6, IL-10, IL-13, IL-17A, IL-21 and TGF-β1 responses, but lower levels of IFN-γ responses were detected in ICOS-Tg mice, which were abrogated by treatment with ICOS blockers in vitro. In addition, significantly higher levels of serum anti-SEA IgG were detected in ICOS-Tg mice.Conclusions/SignificanceThe ICOS-related signaling may promote the pathogenesis of murine schistosomiasis by polarizing Tfh cells, which may be immune check points for the prevention and intervention of schistosomiasis.Author summaryGranulomatous inflammation and fibrosis in the liver are the major pathogenic characteristics of schistosomiasis. ICOS is crucial for the development of Tfh cells, which are the key modulators of B cell activation and humoral immunity. However, the underlying molecular mechanisms are incompletely understood in pathogenesis of schistosomiasis. Here, our results showed that the ICOS over-expression would significantly induce severer liver inflammation and fibrosis, higher frequency of splenic Tfh, higher levels of anti-SEA IgG as well as imbalanced SEA-specific cytokine responses in ICOS-Tg mice. The findings suggested that ICOS signaling may promote the pathogenesis of murine schistosoma-related liver inflammation and fibrosis by polarizing Tfh cells. Potentially, ICOS signaling and Tfh cells may be immune check points for the prevention and intervention of schistosomiasis.

Hepatic fibrosis induced by schistosomes is regulated by a complex network of cytokines. T helper type 9 (Th9) cells are a new type of effector T helper cells, which mainly secrete the specific cytokine interleukin-9 (IL-9). Interleukin-9 has been shown to contribute to liver fibrosis in patients with chronic hepatitis B and in a mouse model due to carbon tetrachloride. However, the role of IL-9 in schistosomiasis fibrosis remains unknown. In this study, we investigated the roles of IL-9 in schistosomiasis through in vivo and in vitro studies. The in vivo studies found that neutralization of IL-9 reduced liver granulomatous inflammation and collagen deposition around parasite eggs. The in vitro studies found that the treatment of primary hepatic stellate cells with IL-9 induced a significant increase of collagen and α-smooth-muscle actin. Moreover, we also described the dynamics and relevance of IL-9 and IL-4 in mice infected with Schistosoma japonicum. We found that IL-9 might appear more quickly and at higher levels than IL-4. Hence, our findings indicated that IL-9 might play a role in regulating hepatic fibrosis in early-stage schistosomiasis and become a promising approach for regulating hepatic fibrosis caused by S. japonicum.

Background Schistosomiasis is a debilitating neglected tropical disease that affects approximately 190 million people around the world. Praziquantel (PZQ) is the only drug available for use against all Schistosoma species. Although PZQ has a high efficacy, recognized concerns have prompted the development of new, alternative drugs for repeated use in endemic areas where PZQ efficacy against strains of Schistosoma is reduced. A hybrid drug containing different pharmacophores within a single molecule is a promising strategy. Our earlier in vivo studies showed the significant antiparasitic activity of a praziquantel derivative, DW-3-15, against Schistosoma japonicum. In the present study, DW-3-15 was synthesized in large amounts by a pharmaceutical company and its schistosomicidal efficacy and stability were further confirmed. Parameters such as parasite viability, pairing and oviposition were evaluated in vitro. An in vivo study was conducted to assess the effect of commercial DW-3-15 on worm burden, egg production and diameter of granulomas. Additionally, to gain insight into the mechanism of action for DW-3-15, morphological changes in the tegument of S. japonicum were also examined. Results The in vitro study showed the antiparasitic activity of DW-3-15 against S. japonicum, with significant reductions in viability of adult and juvenile worms, worm pairings and egg output. Compared to PZQ, DW-3-15 induced similar ultrastructural changes and evident destruction of the tegument surface in male worms. In vivo, the oral administration of DW-3-15 at a dose of 400 mg/kg per day for five consecutive days in mice significantly reduced the total worm burden and number of eggs in the liver. Histological analysis of the livers showed a marked reduction in the average diameter of the egg granuloma. Conclusions Our findings suggest that DW-3-15, a PZQ derivative with the prospect of commercial production, can be developed as a potential promising schistosomicide. Electronic supplementary material The online version of this article (10.1186/s13071-019-3442-7) contains supplementary material, which is available to authorized users.

The pathology of schistosome egg-induced liver granuloma, fibrosis and eventually liver scarring is complicated. CD4+ helper T (Th) cells play critical roles in both host humoral immunity and cellular immunity against parasitic infection and immunopathology in schistosomiasis. Follicular helper T (Tfh) cells are another specialized subset of Th cells and involved in infectious diseases. However, the immune regulatory mechanism of Tfh cells in severe liver pathology of schistosomiasis is still poorly understood. In this study, using a S. japonicum-infected mouse model, we studied the dynamics and effects of Tfh cells in vivo and demonstrated that Tfh phenotype molecules ICOS, PD-1 and functional factor IL-21 were positively correlated with disease development by flow cytometry. Meanwhile, our results also showed that Tfh cells enriched in splenic germinal center (GC) and promoted B cells producing IgM with the progress of hepatic immunopathology by B-T co-culture experiments. More importantly, our data indicated that IL-21 contributed to the formation and development of hepatic egg granuloma and subsequent fibrosis by driving GC responses and activating HSCs by immunohistochemical detection and blocking assay in vitro. Our findings contribute to the better understanding of the immunopathogenesis of schistosomiasis and have implications for therapeutic intervention of hepatic fibrotic diseases.

Background Schistosomiasis japonica is a serious debilitating and sometimes fatal disease. Accurate diagnostic tests play a key role in patient management and control of the disease. However, currently available diagnostic methods are not ideal, and the detection of the parasite DNA in blood samples has turned out to be one of the most promising tools for the diagnosis of schistosomiasis. In our previous investigations, a 230-bp sequence from the highly repetitive retrotransposon SjR2 was identified and it showed high sensitivity and specificity for detecting Schistosoma japonicum DNA in the sera of rabbit model and patients. Recently, 29 retrotransposons were found in S. japonicum genome by our group. The present study highlighted the key factors for selecting a new perspective sensitive target DNA sequence for the diagnosis of schistosomiasis, which can serve as example for other parasitic pathogens. Methodology/Principal Findings In this study, we demonstrated that the key factors based on the bioinformatic analysis for selecting target sequence are the higher genome proportion, repetitive complete copies and partial copies, and active ESTs than the others in the chromosome genome. New primers based on 25 novel retrotransposons and SjR2 were designed and their sensitivity and specificity for detecting S. japonicum DNA were compared. The results showed that a new 303-bp sequence from non-long terminal repeat (LTR) retrotransposon (SjCHGCS19) had high sensitivity and specificity. The 303-bp target sequence was amplified from the sera of rabbit model at 3 d post-infection by nested-PCR and it became negative at 17 weeks post-treatment. Furthermore, the percentage sensitivity of the nested-PCR was 97.67% in 43 serum samples of S. japonicum-infected patients. Conclusions/Significance Our findings highlighted the key factors based on the bioinformatic analysis for selecting target sequence from S. japonicum genome, which provide basis for establishing powerful molecular diagnostic techniques that can be used for monitoring early infection and therapy efficacy to support schistosomiasis control programs., Author Summary Schistosomiasis remains a serious parasitic disease worldwide. Adequate case-finding is important and crucial for the effective control programs as schistosomiasis control programs are chiefly based on treatment of infected populations. However, the currently available diagnostic assays are not ideal, and DNA detection can provide useful alternative approaches for the sensitive and specific diagnosis of schistosomiasis, provided that reliable genetic markers are employed in the tests. However, different target sequences used for DNA detection of samples showed different sensitivity. In previous studies, we identified a 230-bp sequence of high sensitivity and specificity from the retrotransposon SjR2 of Schistosoma japonicum. Here, new primers based on 25 novel retrotransposons were designed and their sensitivities and specificities for detecting S. japonicum DNA were compared. Of these, a new 303-bp DNA sequence from the non-LTR retrotransposon (SjCHGCS19) had high sensitivity and specificity in detecting S. japonicum DNA. More importantly, we also found that both the SjCHGCS19 (303-bp sequence) and SjR2 (230-bp sequence) have high repetitive copies, higher genome proportions and active ESTs in the genome of S. japonicum. Our findings provide new insights into selecting suitable target sequences which may play a key role for the sensitive and specific detection of S. japonicum DNA.