Metabolomics analysis of patients with Schistosoma japonicum infection based on UPLC-MS method.

BACKGROUND: Schistosomiasis is still one of the most serious parasitic diseases. Evidence showed that the metabolite profile in serum can potentially act as a marker for parasitic disease diagnosis and evaluate disease progression and prognosis. However, the serum metabolome in patients with Schistosoma japonicum infection is not well defined. In this study, we investigated the metabolite profiles of patients with chronic and with advanced S. japonicum infection. METHODS: The sera of 33 chronic S. japonicum patients, 15 patients with advanced schistosomiasis and 17 healthy volunteers were collected. Samples were extracted for metabolites and analyzed with ultra-performance liquid chromatography-mass spectrometry (UPLC-MS). RESULTS: We observed significant differences in metabolite profiles in positive and negative ion modes between patients with advanced and chronic S. japonicum infection. In patients with chronic S. japonicum infection, 199 metabolites were significantly upregulated while 207 metabolites were downregulated in advanced infection. These differential metabolites were mainly concentrated in steroid hormone biosynthesis, cholesterol metabolism and bile secretion pathways. We also found that certain bile acid levels were significantly upregulated in the progression from chronic to advanced S. japonicum infection. In receiver operator characteristic (ROC) analysis, we identified three metabolites with area under the curve (AUC) > 0.8, including glycocholic (GCA), glycochenodeoxycholate (GCDCA) and taurochenodeoxycholic acid (TCDCA) concentrated in cholesterol metabolism, biliary secretion and primary bile acid biosynthesis. CONCLUSIONS: This study provides evidence that GCA, GCDCA and TCDCA can potentially act as novel metabolite biomarkers to distinguish patients in different stages of S. japonicum infection. This study will contribute to the understanding of the metabolite mechanisms of the transition from chronic to advanced S. japonicum infection, although more studies are needed to validate this potential role and explore the underlying mechanisms.

Using blood routine indicators to establish a machine learning model for predicting liver fibrosis in patients with Schistosoma japonicum.

This study intends to use the basic information and blood routine of schistosomiasis patients to establish a machine learning model for predicting liver fibrosis. We collected medical records of Schistosoma japonicum patients admitted to a hospital in China from June 2019 to June 2022. The method was to screen out the key variables and six different machine learning algorithms were used to establish prediction models. Finally, the optimal model was compared based on AUC, specificity, sensitivity and other indicators for further modeling. The interpretation of the model was shown by using the SHAP package. A total of 1049 patients' medical records were collected, and 10 key variables were screened for modeling using lasso method, including red cell distribution width-standard deviation (RDW-SD), Mean corpuscular hemoglobin concentration (MCHC), Mean corpuscular volume (MCV), hematocrit (HCT), Red blood cells, Eosinophils, Monocytes, Lymphocytes, Neutrophils, Age. Among the 6 different machine learning algorithms, LightGBM performed the best, and its AUCs in the training set and validation set were 1 and 0.818, respectively. This study established a machine learning model for predicting liver fibrosis in patients with Schistosoma japonicum. The model could help improve the early diagnosis and provide early intervention for schistosomiasis patients with liver fibrosis.

Adult schistosomes have an epithelial bacterial population distinct from the surrounding mammalian host blood.

BACKGROUND: Schistosomiasis is a neglected tropical parasitic and chronic disease affecting hundreds of millions of people. Adult schistosomes reside in the blood stream of the definitive mammalian host. These helminth parasites possess two epithelial surfaces, the tegument and the gastrodermis, both of which interact with the host during immune evasion and in nutrient uptake. METHODS: Female ARC Swiss mice (4-6 weeks old) were infected percutaneously with Schistosoma japonicum cercariae freshly shed from Oncomelania hupensis quadrasi snails (Philippines strain). Fluorescent in situ hybridisation (FISH) was performed by using fresh adult S. japonicum perfused from those infected mice. Adult S. japonicum worms were processed to isolate the tegument from the carcass containing the gastrodermis; blood and bile were collected individually from infected and uninfected mice. Total DNA extracted from all those samples were used for microbiome profiling. RESULTS: FISH and microbiome profiling showed the presence of bacterial populations on two epithelial surfaces of adult worms, suggesting they were distinct not only from the host blood but also from each other. Whereas microbial diversity was reduced overall in the parasite epithelial tissues when compared with that of host blood, specific bacterial taxa, including Anoxybacillus and Escherichia, were elevated on the tegument. Minimal differences were evident in the microbiome of host blood during an active infection, compared with that of control uninfected blood. However, sampling of bile from infected animals identified some differences compared with controls, including elevated levels of Limnohabitans, Clostridium and Curvibacter. CONCLUSIONS: Using FISH and microbial profiling, we were able to demonstrate, for the first time, that bacteria are presented on the epithelial surfaces of adult schistosomes. These schistosome surface-associated bacteria, which are distinct from the host blood microenvironment, should be considered as a new and important component of the host-schistosome interaction. The importance of individual bacterial species in relation to schistosome parasitism needs further elucidation.

Schistosoma japonicum cathepsin B as potential diagnostic antigen for Asian zoonotic schistosomiasis.

In this study, the diagnostic value of Schistosoma japonicum cathepsin B (SjCatB) was evaluated as an antigen for the early detection of S. japonicum infection. SjCatB is a key protease used by the cercaria to penetrate the intact skin of the host for transdermal infection. The early exposure of the host's immune system to this enzyme may elicit early production of antibodies against this molecule. Therefore, the recombinant SjCatB (rSjCatB) was expressed in Escherichia coli with N-terminal 6xHis-tag. rSjCatB was tested for its performance as a diagnostic antigen using indirect enzyme-linked immunosorbent assay (ELISA) with sera from experimentally infected mice collected at > 8 weeks post-infection. Showing 100% sensitivity and 95.0% specificity in the ELISA, rSjCatB was then evaluated with sera from experimentally infected mice collected at 1-7 weeks post-infection to determine how early the antibodies can be detected. Results showed that as early as 6 weeks post-infection, 2 of the 3 infected mice were found to be positive with the antibodies against SjCatB. Furthermore, the potential of the recombinant antigen in detecting human schistosomiasis was evaluated with archived serum samples collected from individuals who had been diagnosed with S. japonicum infection by stool examination. Results showed 86.7% sensitivity and 96.7% specificity suggesting its high diagnostic potential for human schistosomiasis. In addition, SjCatB showed minimal cross-reaction with the sera collected from patients with other parasitic diseases. In conclusion, the results of this study suggest that SjCatB will be useful in the development of a sensitive and specific early detection test for S. japonicum infection.

Comparison of Kato Katz, antibody-based ELISA and droplet digital PCR diagnosis of schistosomiasis japonica: Lessons learnt from a setting of low infection intensity.

BACKGROUND: Zoonotic schistosomiasis in Asia, caused by Schistosoma japonicum, remains a major public health concern in China and the Philippines. The developing epidemiological and socio-economic picture of the disease in endemic areas necessitates the development of affordable and highly accurate field diagnostics as an important component in evaluating ongoing integrated control and elimination efforts. METHODS: Three diagnostic methods, namely Kato-Katz (KK) stool microscopy, ELISA and droplet digital (dd) PCR assays, were compared by detecting infection in a total of 412 participants from an area moderately endemic for schistosomiasis in the Philippines. RESULTS: This comprehensive comparison further defined the diagnostic performance and features for each assay. Compared with the ddPCR assay analysing DNA from faeces (F_ddPCR), which exhibited the highest sensitivity, the SjSAP4 + Sj23-LHD-ELISA had the best accuracy (67.2%) among all five ELISA assays assessed. Schistosomiasis prevalence determined by the SjSAP4 + Sj23-LHD-ELISA and ddPCRs was similar and was at least 2.5 times higher than obtained with the KK method. However, the agreement between these assays was low. In terms of cost and logistical convenience, the SjSAP4 + Sj23-LHD-ELISA represents a cost-effective assay with considerable diagnostic merits. In contrast, although the ddPCR assays exhibited a high level of diagnostic performance, the high cost and the need for specialized equipment presents a major obstacle in their application in screening campaigns. CONCLUSION: The SjSAP4 + Sj23-LHD-ELISA represents a cost-effective tool for the diagnosis of schistosomiasis that could prove an important component in the monitoring of integrated control measures as elimination draws closer, whereas the ddPCR assays, in addition to their high sensitivity and specificity, are capable of quantifying infection intensity. However, the high cost of ddPCR hinders its wider application in screening programs, although it could be a valuable reference in the development and improvement of other diagnostic assays.

Gene Expression in Developmental Stages of Schistosoma japonicum Provides Further Insight into the Importance of the Schistosome Insulin-Like Peptide.

We showed previously that the Schistosoma japonicum insulin-like peptide (SjILP) binds the worm insulin receptors, thereby, activating the parasite's insulin pathway and emphasizing its important role in regulating uptake of glucose, a nutrient essential for parasite survival. Here we show that SjILP is differentially expressed in the schistosome life cycle and is especially highly transcribed in eggs, miracidia, and adult female worms. RNA inference was employed to knockdown SjILP in adults in vitro, with suppression confirmed by significantly reduced protein production, declined adenosine diphosphate levels, and reduction in glucose consumption. Immunolocalization showed that SjILP is located to lateral gland cells of mature intra-ovular miracidia in the schistosome egg, and is distributed on the ciliated epithelium and internal cell masses of newly transformed miracidia. In schistosomula, SjILP is present on the tegument in two antero-lateral points, indicating highly polarized expression during cercarial transformation. Analysis of serum from S. japonicum-infected mice by ELISA using a recombinant form of SjILP as an antigen revealed IgG immunoreactivity to this molecule at 7 weeks post-infection indicating it is likely secreted from mature eggs into the host circulation. These findings provide further insights on ILP function in schistosomes and its essential roles in parasite survival and growth in different development stages.

[Endemic situation of schistosomiasis in national surveillance sites of Jiangsu Province from 2011 to 2018].

OBJECTIVE: To analyze and investigate the changing trend of the endemic situation of schistosomiasis in national surveillance sites of Jiangsu Province from 2011 to 2018, so as to provide scientific evidence for formulating strategies for schistosomiasis control. METHODS: From 2011 to 2014, the national schistosomiasis surveillance sites were set in seven schistosomiasis endemic counties (cities, districts) across Jiangsu Province as according to the National Schistosomiasis Surveillance Scheme (2011 version), and from 2015 to 2018, the national surveillance sites were assigned in all 64 counties (cities, districts) endemic for schistosomiasis in Jiangsu Province according to the National Schistosomiasis Surveillance Scheme (2014 version). Schistosoma japonicum infections in local populations, mobile populations and livestock, and snail status were monitored in the national schistosomiasis surveillance sites of Jiangsu Province from 2011 to 2018, and the monitoring data were statistically analyzed. RESULTS: The sero-prevalence of S. japonicum infections was 1.50% to 4.61% among local populations in the national schistosomiasis surveillance sites of Jiangsu Province from 2011 to 2018, and a higher sero-prevalence was seen in men than in women, with the sero-positives predominantly detected in local populations at ages of over 50 years. The positive rate of stool examinations was 0 to 0.14% among sero-positive local populations in the national schistosomiasis surveillance sites of Jiangsu Province from 2011 to 2018, and no acute case was found in local populations during the study period. The sero-prevalence of S. japonicum infections was 0.46% to 15.97% among mobile populations in the national schistosomiasis surveillance sites of Jiangsu Province from 2011 to 2018, and no egg-positives were identified. A total of 1 453 livestock were tested in the national schistosomiasis surveillance sites of Jiangsu Province from 2011 to 2018, and no S. japonicum infections were detected. During the period from 2011 through 2018, snail survey was conducted in an area of 216 million m2 in the national schistosomiasis surveillance sites of Jiangsu Province, and 1 291.01 hm2 snail habitats were identified, with snail densities ranging from 0.01 to 0.47 snails/0.1 m2; however, no S. japonicum infections were identified in snails. CONCLUSIONS: The overall endemic situation of schistosomiasis appears a tendency towards a decline in Jiangsu Province, and S. japonicum infection remains at a low level in both humans and livestock. No S. japonicum infection has been identified in local populations in Jiangsu Province since 2012. In the future, monitoring and management of imported sources of S. japonicum infections should be intensified in Jiangsu Province, and the capability building of passive surveillance of schistosomiasis should be improved in sentinel hospitals in national schistosomiasis surveillance sites of Jiangsu Province. In addition, the examination of schistosomiasis should be strengthened in mobile populations in Jiangsu Province, a sensitive and effective surveillance-response system for schistosomiasis is urgently needed.

Circulating miRNAs as footprints for liver fibrosis grading in schistosomiasis.

BACKGROUND: Chronic infection with Schistosoma japonicum or S. mansoni results in hepatic fibrosis of the human host. Staging fibrosis is crucial for the prognosis and to determine the rapid need of treatment in patients with schistosomiasis. METHODS: To establish whether there is a correlation between circulating microRNA (miRNA) level and fibrosis progression in schistosomiasis, ten miRNAs were selected to assess their potential in grading schistosomiasis liver fibrosis. This was done firstly in two mouse strains (C57BL/6 and BALB/c) to determine the temporal expression profiles in serum over the course of S. japonicum infection, and then within a cohort of 163 schistosomiasis japonica patients with different grades of liver fibrosis. FINDING: Four miRNAs (miR-150-5p, let-7a-5p, let-7d-5p and miR-146a-5p) were able to distinguish patients with mild versus severe fibrosis. The level of serum miR-150-5p showed the most promising potential for grading hepatic fibrosis in schistosomiasis. The diagnostic performance of miR-150-5p in discriminating mild from severe fibrosis is comparable with that of the ELF test and serum HA level. In addition, the serum levels of the four miRNAs rebounded in infected C57BL/6 mice, after 6 months post treatment, following the regression of liver fibrosis, thereby providing further support for the utility of these miRNAs in grading schistosomal hepatic fibrosis. INTERPRETATION: Circulating miRNAs can be a supplementary tool for assessing hepatic fibrosis in human schistosomiasis. FUND: National Health and Medical Research Council (NHMRC) of Australia (APP1102926, APP1037304 and APP1098244).

Antinuclear antibodies and interleukin responses in patients with Schistosoma japonicum infection.

Schistosomiasis poses a serious threat to public health, and the infection will develop into chronic and advanced late-stage disease if not treated. Apart from the clinical signs due to immune reactions to schistosome eggs trapped in host tissues, it also increases the risk for the development of autoimmunity reflected by dysfunctional, auto-reactive antibodies. Antinuclear antibodies (ANA) have been reported in schistosomiasis due to S. mansoni and S. haematobium. We demonstrate ANA in schistosomiasis japonica and explore the relationship between this infection and autoimmune disease by measuring ANA and interleukin (IL)-10, IL-12 and IL-17 responses in the sera of 125 Chinese patients with different stages of schistosomiasis japonica. The incidence rates of ANA in the patients with acute, chronic and late stages of schistosomiasis infection were 6.7%, 23.3% and 70.0%, respectively, with statistically significant differences between each stage (P = 0.000). IL-17 concentrations were high at the acute stage of schistosomiasis compared to the other stages of the disease (P = 0.000). This pattern was also seen for IL-10 and IL-12 concentrations (P = 0.01). IL concentrations in patients in the chronic and late stages of the disease were low and showed no difference compared to the healthy adults.

A perspective for improving the sensitivity of detection: The application of multi-epitope recombinant antigen in serological analysis of buffalo schistosomiasis.

The sensitivity and specificity are two crucial aspects of addressing the efficacy of diagnostic antigens. Achilles' heel of low sensitivity rate exists in current diagnostic recombinant antigens for schistosomiasis detection. This study focused on the diagnosis of water buffalo schistosomiasis japonica and a perspective of improving recombinant antigens' sensitivity was assessed using archived 220 water buffalo sera (114 positive sera, 92 negative sera and 14 Paramphistomum-infected sera) and the method of enzyme-linked immunosorbent assay (ELISA). The subjects included two trivalent recombinant proteins, one bivalent antigen and two single-molecular antigens. The crude antigen SEA (soluble egg antigen) was employed as reference antigen. The highest sensitivity rate in the five recombinant antigens assigned to the trivalent multi-epitope antigen PA4 (95.61%, 109/114), no significant difference with SEA (100%, 114/114, p = .836), and showing remarkable differences with the two single-molecular antigens (p < 0.01). In term of specificity, two trivalent multi-epitope antigens PA4 (97.83%, 90/92), PA5 (100%, 92/92) and the bivalent antigen PA3 (98.91%, 91/92) had few differences with one monovalent antigens PA1 (97.83%, 90/92, p = .304/0.103/0.640), significant differences with another monovalent antigens PA2 (92.39%, 85/92, p < 0.01) and SEA (82.61%, 76/92, p < 0.01). Additional, all the recombinant antigens had low cross-reactivity (7.14%, 1/14, 0% for PA5) with serum samples of paramphistomiasis, contrast with that of SEA (50%, 7/14, p < 0.01). The results indicated that multi-epitope antigens have the possibility to improve diagnostic sensitivity and the trivalent multi-epitope antigen PA4 possesses greater likelihood to be a diagnostic antigen for water buffalo schistosomiasis.

[Changes of serum anti-schistosome antibody levels in schistosomiasis japonica patients after treatment].

OBJECTIVE: To investigate the changes of serum anti-schistosome antibody titers in schistosomiasis japonica patients after treatment, in order to provide the evidence for formulating the schistosomiasis surveillance program in marshland and lake regions. METHODS: Upon prospective cohort study, the stool examination positive schistosomiasis patients and blood examination positive suspected patients (the titer was more than 1:80, including 1:80) were selected as the research objects in Jiangling County in 2014, and they received the 2-day praziquantel therapy. Half year, one year and two years after the treatment, their blood samples and fecal samples were collected for IHA anti-schistosome antibody detections and schistosome egg and miracidium detections. RESULTS: In 2014, the stool examination positives were 251, and the majority of them were over 41 years old, accounting for 93.23% (234/251) ; 581 cases of high antibody titers were detected by the IHA method, and the majority of them were over 41 years old, accounting for 89.16% (518/581) . Half year, one year and two years after the treatment, among the stool examination positives, the negative conversion rates of stool positives were 99.60% (250/251), 100% (239/239) and 100% (234/234) respectively and the negative conversion rates of antibody positives were 21.91% (55/251), 64.11% (156/239) and 76.89% (193/234) respectively. In the high antibody titer positives, the negative conversion rates were 38.04% (221/581), 64.11% (359/560), and 77.86% (429/551) respectively, Half year, one year and two years after the treatment. There were statistically significant differences among the antibody negative conversion rates by χ2 test (χ2 = 77.538, 183.412, 25.469 respectively, all P < 0.001) . The geometric mean values of antibody titers of different durations between 2 groups were analyzed by 2-independent-samples T test, and the geometric mean values of antibody titers between the 2 groups were different before the treatment (t = 23.576, P < 0.01), but the geometric mean values of antibody titers between the 2 groups were not different 6 months, 1 year and 2 years after the treatment (t = -0.046, 1.165, -0.132, P = 0.964, 0.245, 0.895 respectively). CONCLUSIONS: The levels of serum anti-schistosome antibody degrade slowly in schistosomiasis japonica patients after the treatment, and the results of IHA tests cannot distinguish the current schistosome infection from previous schistosome infection. Therefore, it is necessary to develop the specific diagnostic technology for schistosome infection in order to meet the need of monitoring.

Population based and animal study on the effects of Schistosoma japonicum infection in the regulation of host glucose homeostasis.

Although parasitic infection affects the glucose homeostasis of mice, only few studies have integrated epidemiological and animal data to determine the effect of Schistosoma japonicum infection on mice metabolism. The current study assessed the effects of S. japonicum infection on blood glucose and other metabolic parameters in both patients and animal models of chronic schistomiasis. A total of 2183 patients with chronic schistosomiasis and age- and gender-matched individuals without schistosomiasis (n = 1798) were enrolled in this study. Fasting blood glucose and other metabolic parameters, including body mass index (BMI) and serum triglyceride and total cholesterol, were compared between the two groups. Mice infected with S. japonicum were used to test the effects of the parasite on glucose tolerance. We found that chronic schistosomiasis patients had significantly lower BMI and fasting blood glucose, serum triglyceride, and total cholesterol levels than non-schistosomiasis individuals. In the animal studies, both bisexual and unisexual S. japonicum infection improved glucose tolerance in wild-type mice. Additionally, S. japonicum-infected ob/ob mice, a model that spontaneously develops obesity and diabetes, also had decreased body weight and improved glucose tolerance. We further observed that S. japonicum-infected mice had lower inflammatory gene expression in the visceral white adipose tissue than the control mice. Collectively, our results demonstrated that S. japonicum infection improved glucose tolerance and other metabolic parameters both in human and animals. Downregulated inflammatory gene expression due to S. japonicum infection might be among the mechanisms for the improved glucose tolerance.

The regulation of regulation: interleukin-10 increases CD4+ CD25+ regulatory T cells but impairs their immunosuppressive activity in murine models with schistosomiasis japonica or asthma.

CD4+ CD25+ Foxp3+ regulatory T (Treg) cells play an important role in maintaining immune homeostasis. Interleukin-10 (IL-10), a cytokine with anti-inflammatory capacities, also has a critical role in controlling immune responses. In addition, it is well known that production of IL-10 is one of the suppression mechanisms of Treg cells. However, the action of IL-10 on Treg cells themselves remains insufficiently understood. In this study, by using a Schistosoma japonicum-infected murine model, we show that the elevated IL-10 contributed to Treg cell induction but impaired their immunosuppressive function. Our investigations further suggest that this may relate to the up-regulation of serum transforming growth factor (TGF-ß) level but the decrease in membrane-bound TGF-ß of Treg cells by IL-10 during S. japonicum infection. In addition, similar IL-10-mediated regulation on Treg cells was also confirmed in the murine model of asthma. In general, our findings identify a previously unrecognized opposing regulation of IL-10 on Treg cells and provide a deep insight into the precise regulation in immune responses.

Nested-PCR assay for detection of Schistosoma japonicum infection in domestic animals.

BACKGROUND: Schistosomiasis japonica is a common zoonosis. Domestic animals are the primary source of infection and play an important role in disease transmission. The prevalence and infectivity of this disease in domestic animals in China have significantly decreased and, for this reason, diagnostics with a higher sensitivity have become increasingly necessary. It was reported that polymerase chain reaction (PCR)-based methods could be used to detect schistosome infection in humans and animals and presented a high sensitivity and specificity. The present study aimed to develop a PCR-based method for detection of Schistosoma japonicum infection in domestic animals. METHODS: A specific nested-PCR assay was developed to detect S. japonicum infection in domestic animals via amplification of a 231-bp DNA fragment of retrotransposon SjR2. The developed assay was first used in sera and dry blood filter paper (DBFP) from goats and buffaloes at different time points of infection. Then, 78 DBFPs from 39 artificially-infected bovines at 14 and 28 days post-infection and 42 DBFPs from schistosome-negative bovines from the city of Huangshan in the Anhui province were used to evaluate the diagnostic validity. Furthermore, this assay was used to detect S. japonicum infection in domestic animals in Dongzhi and Wangjiang counties. RESULTS: The expected PCR product was detected in eggs and adult worms of S. japonicum and blood samples from S. japonicum-infected goats and water buffaloes, but not from Fasciola and Haemonchus contortus worms. The nested-PCR assay could detect the target S. japonicum DNA in DBFPs from goats and buffaloes after day 3 post-infection. The sensitivity in buffaloes at 14 and 28 days post-infection was 92.30% (36/39) and 100% (39/39), respectively. The specificity was 97.60% (41/42). The positivity rates in Dongzhi and Wangjiang counties were 6.00% and 8.00% in bovines and 22.00% and 16.67% in goats, respectively. The positivity rates in goats in both counties were higher than those in bovines with a significant difference in Dongzhi County but not in Wangjiang County (P < 0.05 and P = 0.23, respectively). CONCLUSIONS: Our results suggest that the developed nested-PCR assay may be used for the diagnosis of S. japonicum infection in domestic animals, and the control of S. japonicum infection in goats should be paid more attention.

Early detection of circulating DNA of Schistosoma japonicum in sentinel mice models.

Currently in China, the schistosomiasis control program has shifted its focus from transmission control to the elimination of the disease. Effective forecast and surveillance systems of schistiosomiasis are of great importance for issuing timely and early warnings on risk of infection, and therefore implementing preventive measures to avoid infection. There is great demand in more sensitive and specific methods to improve the surveillance system for early detection of S. japonicum infection in sentinel mice. In this study, we reported a sensitive nested-PCR assay targeting a 303-bp fragment from highly repetitive retrotransposon SjCHGCS19 to detect the S. japonicum DNA in sera of experimental mice. Meanwhile, detection efficacy of the nested-PCR was compared with two conventional methods for field monitoring schistosomiasis such as ELISA and IHA. The nested-PCR assay could detect the specific DNA at 3-day post-infection in sera of mice with 5 cercariae infection, while for ELISA and IHA, both show negative results even after 2 weeks post-infection in mice with 20 cercariae infection. Our results demonstrated the DNA-based assay was more sensitive to make early diagnosis of S. japonicum infection in sentinel mice models, which will improve the early-warning ability of schistosomiasis surveillance system.

IL-33 Contributes to Schistosoma japonicum-induced Hepatic Pathology through Induction of M2 Macrophages.

Interleukin (IL)-33 is involved in T helper (Th)2-biased immune responses in mice infected with Schistosoma, but the precise mechanism remains to be elucidated. Herein, we investigated the role of IL-33 and its receptor ST2L in hepatic granuloma pathology induced by Schistosoma japonicum infection. We found that IL-33 induced the increased production of IL-5 and IL-13 from splenocytes and liver mononuclear cells (MNCs) of infected mice. The infected mice developed significantly higher number of ST2L-expressing cells in spleen and liver. Most of the ST2L-expressing cells in liver were F4/80(+) macrophages, indicating the key role of macrophages in the response to IL-33. However, the liver MNCs in male-only worm infection had a poor response to IL-33, though elevated serum IL-33 was observed. ST2L(+)F4/80(+) cells were lower in male-only worm infection than that of mixed infection. IL-33 and soluble egg antigen (SEA) upregulated ST2L expression on macrophages in vitro and ST2L-expressing macrophage displayed MHCII(-)CD11b(+)M2 phenotype. Macrophage deletion significantly attenuated IL-33-induced type 2 immunity and egg granuloma formation during S. japonicum infection. These data demonstrate that IL-33 contributes to hepatic granuloma pathology through induction of M2 macrophages during S. japonicum infection.

Saposin-like Proteins, a Multigene Family of Schistosoma Species, are Biomarkers for the Immunodiagnosis of Schistosomiasis Japonica.

BACKGROUND: One major obstacle to schistosomiasis prevention and control is the lack of accurate and sensitive diagnostic approaches, which are essential for planning, targeting, and evaluating disease control efforts. METHODS: Based on bioinformatics analysis, we identified a multigene family of saposin-like protein (SAPLP) in the schistosome genomes. Schistosoma japonicum SAPLPs (SjSAPLPs), including recently reported promising biomarker SjSP-13, were systematically and comparatively assessed as immunodiagnostic antigens for schistosomiasis japonica. RESULTS: Two novel antigens (SjSAPLP4 and SjSAPLP5) could specifically react to serum samples from both S. japonicum-infected laboratory animals and patients. The sensitivities of SjSAPLP4, SjSAPLP5, and SjSP-13 for immunodiagnosis were 98% (95% confidence interval, 88.0%-99.9%), 96% (85.1%-99.3%), and 88% (75.0%-95.0%), respectively, and 100% (91.1%-100%) specificity was observed for the 3 antigens with enzyme-linked immunosorbent assay; there was no cross-reaction with clonorchiosis (0 of 19 patients), echinococcosis (0 of 20 patients), or trichinellosis (0 of 18 patients) for the 3 antigens. Antibodies to the 3 antigens could be detected in the serum samples of rabbits infected with 1000 cercariae as early as 3-4 weeks after infection. CONCLUSIONS: These results suggest that SjSAPLP4 and SjSAPLP5 could serve as novel biomarkers for the immunodiagnosis of schistosomiasis japonica, which will further improve diagnostic sensitivity and specificity.

Circulating miRNAs: Potential Novel Biomarkers for Hepatopathology Progression and Diagnosis of Schistosomiasis Japonica in Two Murine Models.

BACKGROUND: Schistosomiasis remains a major public health issue, with an estimated 230 million people infected worldwide. Novel tools for early diagnosis and surveillance of schistosomiasis are currently needed. Elevated levels of circulating microRNAs (miRNAs) are commonly associated with the initiation and progression of human disease pathology. Hence, serum miRNAs are emerging as promising biomarkers for the diagnosis of a variety of human diseases. This study investigated circulating host miRNAs commonly associated with liver diseases and schistosome parasite-derived miRNAs during the progression of hepatic schistosomiasis japonica in two murine models. METHODOLOGY/PRINCIPAL FINDINGS: Two mouse strains (C57BL/6 and BALB/c) were infected with a low dosage of Schistosoma japonicum cercariae. The dynamic patterns of hepatopathology, the serum levels of liver injury-related enzymes and the serum circulating miRNAs (both host and parasite-derived) levels were then assessed in the progression of schistosomiasis japonica. For the first time, an inverse correlation between the severity of hepatocyte necrosis and the level of liver fibrosis was revealed during S. japonicum infection in BALB/c, but not in C57BL/6 mice. The inconsistent levels of the host circulating miRNAs, miR-122, miR-21 and miR-34a in serum were confirmed in the two murine models during infection, which limits their potential value as individual diagnostic biomarkers for schistosomiasis. However, their serum levels in combination may serve as a novel biomarker to mirror the hepatic immune responses induced in the mammalian host during schistosome infection and the degree of hepatopathology. Further, two circulating parasite-specific miRNAs, sja-miR-277 and sja-miR-3479-3p, were shown to have potential as diagnostic markers for schistosomiasis japonica. CONCLUSIONS/SIGNIFICANCE: We provide the first evidence for the potential of utilizing circulating host miRNAs to indicate different immune responses and the severity of hepatopathology outcomes induced in two murine strains infected with S. japonicum. This study also establishes a basis for the early and cell-free diagnosis of schistosomiasis by targeting circulating schistosome parasite-derived miRNAs.

Tissue Transglutaminase-Regulated Transformed Growth Factor-ß1 in the Parasite Links Schistosoma japonicum Infection with Liver Fibrosis.

Transforming growth factor (TGF-ß1) is among the strongest factors of liver fibrogenesis, but its association with Schistosoma-caused liver fibrosis is controversial. Tissue transglutaminase (tTG) is the principal enzyme controlling TGF-ß1 maturation and contributes to Sj-infected liver fibrosis. Here we aim to explore the consistency between tTG and TGF-ß1 and TGF-ß1 source and its correlation with liver fibrosis after Sj-infection. TGF-ß1 was upregulated at weeks 6 and 8 upon liver fibrosis induction. During tTG inhibition, TGF-ß1 level decreased in sera and liver of infected mice. TGF-ß1 showed positive staining in liver containing Sj adult worms and eggs. TGF-ß1 was also detected in Sj adult worm sections, soluble egg antigen and Sj adult worm antigen, and adult worms' culture medium. The TGF-ß1 mature peptide cDNA sequence and its extended sequence were amplified through RT-PCR and RACE-PCR using adult worms as template, and sequence is analyzed and loaded to NCBI GenBank (number GQ338152.1). TGF-ß1 transcript in Sj eggs was higher than in adult worms. In Sj-infected liver, transcriptional level of TGF-ß1 from Sj, but not mouse liver, correlated with liver fibrosis extent. This study provides evidence that tTG regulates TGF-ß1 and illustrates the importance of targeting tTG in treating Sj infection-induced fibrosis.

Serological Prevalence of Schistosoma japonicum in Mobile Populations in Previously Endemic but Now Non-Endemic Regions of China: A Systematic Review and Meta-Analysis.

BACKGROUND: Schistosomiasis japonica has been resurging in certain areas of China where its transmission was previously well controlled or interrupted. Several factors may be contributing to this, including mobile populations, which if infected, may spread the disease. A wide range of estimates have been published for S. japonicum infections in mobile populations, and a synthesis of these data will elucidate the relative risk presented from these groups. METHODS: A literature search for publications up to Oct 31, 2014 on S. japonicum infection in mobile populations in previously endemic but now non-endemic regions was conducted using four bibliographic databases: China National Knowledge Infrastructure, WanFang, VIP Chinese Journal Databases, and PubMed. A meta-analysis was conducted by pooling one arm binary data with MetaAnalyst Beta 3.13. The protocol is available on PROSPERO (No. CRD42013005967). RESULTS: A total of 41 studies in Chinese met the inclusion criteria, covering seven provinces of China. The time of post-interruption surveillance ranged from the first year to the 31st year. After employing a random-effects model, from 1992 to 2013 the pooled seroprevalence ranged from 0.9% (95% CI: 0.5-1.6%) in 2003 to 2.3% (95% CI: 1.5-3.4) in 1995; from the first year after the disease had been interrupted to the 31st year, the pooled seroprevalence ranged from 0.6% (95% CI: 0.2-2.1%) in the 27th year to 4.0% (95%CI: 1.3-11.3%) in the second year. The pooled seroprevalence in mobile populations each year was significantly lower than among the residents of endemic regions, whilst four papers reported a lower level of infection in the mobile populations than in the local residents out of only 13 papers which included this data. CONCLUSIONS: The re-emergence of S. japonicum in areas which had previously interrupted transmission might be due to other factors, although risk from re-introduction from mobile populations could not be excluded.