Sja-let-7 suppresses the development of liver fibrosis via Schistosoma japonicum extracellular vesicles

Schistosomiasis is a fatal zoonotic parasitic disease that also threatens human health. The main pathological features of schistosomiasis are granulomatous inflammation and subsequent liver fibrosis, which is a complex, chronic, and progressive disease. Extracellular vesicles (EVs) derived from schistosome eggs are broadly involved in host-parasite communication and act as important contributors to schistosome-induced liver fibrosis. However, it remains unclear whether substances secreted by the EVs of Schistosoma japonicum, a long-term parasitic "partner" in the hepatic portal vein of the host, also participate in liver fibrosis. Here, we report that EVs derived from S. japonicum worms attenuated liver fibrosis by delivering sja-let-7 into hepatic stellate cells (HSCs). Mechanistically, activation of HSCs was reduced by targeting collagen type I alpha 2 chain (Col1α2) and downregulation of the TGF-β/Smad signaling pathway both in vivo and in vitro. Overall, these results contribute to further understanding of the molecular mechanisms underlying host-parasite interactions and identified the sja-let-7/Col1α2/TGF-β/Smad axis as a potential target for treatment of schistosomiasis-related liver fibrosis.

Pathology and molecular mechanisms of Schistosoma japonicum-associated liver fibrosis

Schistosomiasis has been widely disseminated around the world, and poses a significant threat to human health. Schistosoma eggs and soluble egg antigen (SEA) mediated inflammatory responses promote the formation of egg granulomas and liver fibrosis. With continuous liver injuries and inflammatory stimulation, liver fibrosis can develop into liver cirrhosis and liver cancer. Therefore, anti-fibrotic therapy is crucial to increase the survival rate of patients. However, current research on antifibrotic treatments for schistosomiasis requires further exploration. In the complicated microenvironment of schistosome infections, it is important to understand the mechanism and pathology of schistosomiasis-associated liver fibrosis(SSLF). In this review, we discuss the role of SEA in inhibiting liver fibrosis, describe its mechanism, and comprehensively explore the role of host-derived and schistosome-derived microRNAs (miRNAs) in SSLF. Inflammasomes and cytokines are significant factors in promoting SSLF, and we discuss the mechanisms of some critical inflammatory signals and pro-fibrotic cytokines. Natural killer(NK) cells and Natural killer T(NKT) cells can inhibit SSLF but are rarely described, therefore, we highlight their significance. This summarizes and provides insights into the mechanisms of key molecules involved in SSLF development.

[Imbalance of Th17/Tregs promotes egg granuloma formation of liver with Schistosomiasis japonicum in mice]

Objectives To investigate the effect of the imbalance of Th17/Treg on egg granuloma formation of liver with Schistosomiasis japonicum. Methods The BALB/c mice were infected with Schistosoma japonicum cercariae to establish a model of Schistosomiasis japonica. The blood samples, liver tissues and spleen tissue were harvested at the 2nd, 4th, 6th, 8th week, respectively. HE staining and Masson staining were performed to assess the pathological characteristics of the liver. Flow cytometry (FCM) was conducted to evaluate the proportion of CD4⁺ T cell subsets including Th17 cells and Tregs in liver and spleen tissue. The quantitative real-time PCR (qRT-PCR) was carried out to investigate the mRNA level of cytokines including RORγt, FOXP3, IL-6, IL-17, IL-23 and IL-10 in liver tissues. Finally, ELISA was performed to assess the serum level of cytokines including IL-6, IL-17, IL-23 and TGF-β. Schistosoma japonicium soluble egg antigen (SjSEA) were prepared to stimulate mouse spleen cells in vitro. qRT-PCR was carried out to investigate the mRNA level of cytokine including RORγt and FOXP3 and ELISA was performed to assess the expression level of cytokines including IL-6, IL-17, IL-23 and TGF-β at different time points. Results HE and Masson staining demonstrated that inflammatory cell infiltration, schistosome egg granuloma formation and the collagen deposition increased in the liver tissue after the 4th week. The longer the infection, the more severe the liver pathology. In the liver and spleen tissues, the percentage of Th17 cells of infection group (2nd, 4th and 6th weeks) were significantly higher than the healthy group. The percentage of Tregs in the liver tissues of infection group (4th, 6th and 8th weeks) were significantly higher than the healthy group, and the percentage of Tregs in the spleen of infection group (2nd and 4th weeks) were significantly higher than the healthy group. Th17/Treg ratios in the liver of infection group were lower than the healthy group. Th17/Treg ratios in the spleen of infection group (2nd and 4th weeks) were lower than the healthy group, while it increased in the 6th week. At the same time, the levels of Th17 cells and Tregs related nuclear transcription factors and cytokines showed similar dynamic changes as the percentages of T cell subsets. SjSEA can induce the differentiation of Th17 and Tregs and the expression of related cytokines and transcription factors. Conclusion Th17 cells may play a major role in liver pathology, and the imbalance of Th17 cells/Tregs was closely related to the schistosome egg granuloma formation.

Genome-Wide Association Study Identifies New Risk Loci for Progression of Schistosomiasis Among the Chinese Population

Schistosoma japonicum infections, which lead to local inflammatory responses to schistosome eggs trapped in host tissues, can result in long-term, severe complications. The development of schistosomiasis may result from a complex interaction between the pathogenic, environmental, and host genetic components. Notably, the genetic factors that influence the development of schistosomiasis complications are poorly understood. Here we performed a genome-wide association study on multiple schistosomiasis-related phenotypes of 637 unrelated schistosomiasis patients in the Chinese population. Among three indicators of liver damage, we identified two novel, genome-wide significant single-nucleotide polymorphisms (SNPs) rs34486793 (P = 1.415 × 10^-8) and rs2008259 (P = 6.78 × 10^-8) at locus 14q32.2 as well as a gene, PMEPA1, at 20q13.31 (index rs62205791, P = 6.52 × 10^-7). These were significantly associated with serum levels of hyaluronic acid (HA). In addition, RASIP1 and MAMSTR at 19q13.33 (index rs62132778, P = 1.72 × 10^-7) were significantly associated with serum levels of aspartate aminotransferase (AST), and TPM1 at 15q22.2 (index rs12442303, P = 4.39 × 10^-7) was significantly associated with serum levels of albumin. In schistosomiasis clinical signs, ITIH4 at 3p21.1 (index rs2239548) was associated with portal vein diameter (PVD) class, an indicator of portal hypertension, and OGDHL at 10q11.23 (index rs1258172) was related to ascites grade. We also detected an increased expression of these six genes in livers of mice with severe schistosomiasis. Summary data-based Mendelian randomization analyses indicated that ITIH4, PMEPA1 and MAMSTR were pleiotropically associated with PVD class, HA and AST, respectively.

Analysis of CT characteristics in the diagnosis of Schistosoma japonicum associated appendicitis with clinical and pathological correlation: a diagnostic accuracy study

PURPOSE

To clarify unique non-contrast CT (NCCT) characteristics for early recognition of Schistosomal associated appendicitis (SAA) differentiating from Non-schistosomal associated appendicitis (NSA).

MATERIAL AND METHODS

Clinical and pathological data of 50 cases with SAA and 60 cases with NSA who underwent emergency appendectomy were retrospectively compared to pre-surgical NCCT features such as direct and indirect signs of acute appendicitis as well as appendicoliths, colon calcifications as diagnostic criteria. Statistical methods such as Chi-square (χ²), t-tests, Principal component analysis (PCA), Binary Logistic regression (LR) and Factor Analysis (FA) were utilized to observe differences and isolate recognizable CT features of SAA. Pre and post hoc diagnostic performance of all criteria was calculated as sensitivity, specificity, and the Odds Ratio (OR).

RESULTS

Age > 50 years, diameter > 13 mm, pneumatosis, peri appendiceal abscess, focal wall defect, perforation; Orbital, linear and point types of appendicular wall calcifications; sigmoid colon and cecal curvilinear calcifications were observed as unique characteristics with a sensitivity of 84-95% and specificity of 91-98% in predicting SAA by OR of 6.2 times. Pre and post hoc hypothetical analysis did not show any significance for all other factors.

CONCLUSION

Factors such as elderly age, CT features such as larger appendicular diameter, appendicular wall calcifications along with sigmoid colon, and cecal calcifications, signs of perforation or abscess are characteristic for early recognition of SAA.

Improvement of Mitochondrial Activity and Fibrosis by Resveratrol Treatment in Mice with Schistosoma japonicum Infection

Schistosomiasis caused by Schistosoma japonicum is a major parasitic disease in the People's Republic of China. Liver fibrosis is the main pathological mechanism of schistosomiasis, and it is also the major lesion. The common drug used for its treatment, praziquantel (PZQ), does not have a marked effect on liver fibrosis. Resveratrol (RSV), which is an antioxidant, improves mitochondrial function and also attenuates liver fibrosis. The combination of PZQ and RSV has been found to have a synergistic antischistosomal effect on Schistosoma mansoni; additionally, the activity of PZQ is enhanced in the presence of RSV. Here, we examine the therapeutic effects of RSV on the S. japonicum infection in a mouse model, and we investigate RSV as a novel therapeutic agent for mitochondrial function and schistosomiasis-associated liver fibrosis (SSLF). Mitochondrial membrane potential was examined using flow cytometry analysis. The expression of the mitochondrial biogenesis genes PGC-α and fibrosis-associated genes collagen I, collagen III and α-SMA were examined using western blot analysis. Fibrosis-associated histological changes were examined using Masson trichrome staining. Additionally, the effects of RSV on S. japonicum adult worms were examined using scanning electron microscopy and transmission electron microscopy. RSV treatment improved mitochondrial function by increasing membrane potential and increasing PGC-α expression (mitochondrial biogenesis). Further, RSV attenuated liver injury, including liver scarring, by decreasing collagen deposition and the extent of fibrosis, based on the decrease in expression of the fibrosis-related genes. RSV also decreased the adult worm count and caused considerable physical damage to the worm. These results indicate that RSV upregulates mitochondrial biogenesis and inhibits fibrosis. RSV may have potential as a therapeutic target for the treatment of fibrosis in schistosomiasis.

Toll-like receptor-2 regulates macrophage polarization induced by excretory-secretory antigens from Schistosoma japonicum eggs and promotes liver pathology in murine schistosomiasis

Schistosomiasis is endemic to many regions of the world and affects approximately 200 million people. Conventional adaptive T cell responses are considered to be the primary contributors to the pathogenesis of Schistosoma japonicum infection, leading to liver granuloma and fibrosis. However, the functional polarization of macrophages and the associated underlying molecular mechanisms during the pathogenesis of schistosomiasis remains unknown. In the present study, we found that excretory-secretory (ES) antigens derived from S. japonicum eggs can activate macrophages, which exhibit an M2b polarization. Furthermore, ES antigen-induced M2b polarization was found to be dependent on enhanced NF-κB signaling mediated by the MyD88/MAPK pathway in a TLR2-dependent manner. In addition, the cytokine profile of the liver macrophages from wild-type-infected mice are quite distinct from those found in TLR2 knockout-infected mice by quantitative PCR analysis. More importantly, the size of granuloma and the severity of the fibrosis in the livers of TLR2^-/- mice were significantly reduced compared to that in WT mice. Our findings reveal a novel role for M2b polarization in the pathogenesis of schistosome infection.

Schistosomiasis is a global health concern that affects primarily tropical and subtropical areas. During a schistosome infection, the eggs are trapped in the host liver and products derived from eggs induce a polarized Th2 response, resulting in granuloma formation and eventually fibrosis. Thus, it is important to elucidate the mechanism of granuloma formation and fibrosis development. Here, we show that activated macrophages play a novel role in the promotion of hepatic granuloma formation and liver fibrosis in a Schistosoma japonicum-infected mouse model. In addition, M2b polarization induced by egg products was dependent on enhanced NF-κB signaling mediated by the MyD88/MAPK pathway in a TLR2-dependent manner. Our findings reveal a novel role and mechanism of M2b polarization in the liver pathogenesis in S. japonicum-infected mice.

The ratio of the seroprevalence to the egg-positive prevalence of Schistosoma japonicum in China: a meta-analysis

BACKGROUND

Schistosomiasis, caused by Schistosoma japonicum, remains one of the most important parasitic diseases, and detection of S. japonicum infections in humans plays a crucial role in control and treatment. However, comparisons between the parasitological and the immunological examinations in the fields of China are lacking. Therefore we performed a meta-analysis to compare the seroprevalence of Schistosoma japonicum, as determined by IHA or ELISA, with coprological prevalence, as determined by Kato-Katz, and estimate the ratio of the serological to the egg-positive prevalence in order to evaluate the potential threat of egg-negative but worm-positive schistosomiasis.

METHODS

Studies published up to July 2018 on the parasitological and immunological examinations of schistosomiasis in the fields of China were searched in five databases including CNKI, WanFang, VIP, PubMed and Web of Science. The ratio of the serological to the egg-positive prevalence and its 95%CI for each study were calculated, and then point estimates and their 95%CIs of pooled prevalence ratio were meta-analyzed. Subgroup meta-analyses were also performed according to potential influential factors.

RESULTS

A total of 23 articles were included. The prevalence ratio varied from 0.57 to 48.83 for IHA to Kato-Katz and ranged from 0.38 to 13.97 for ELISA to Kato-Katz. The pooled ratio was 4.72 (95%CI: 3.87~ 5.76) for IHA to KK and 4.65 (95%CI: 3.50~ 6.17) for ELISA to KK. Subgroup analyses implied that the ratio of the serological to the egg-positive prevalence may decrease with the endemic levels. The highest prevalence ratio was observed when Kato-Katz was performed with three slides per stool or in hilly and mountainous regions.

CONCLUSIONS

The worm-determined prevalence by IHA or ELISA is 4- to 5-fold higher than the egg-determined prevalence by Kato-Katz, which implied Kato-Katz may largely underestimate the prevalence of S. japonicum in China. The degree of underestimation was greater when Kato-Katz with three slides per stool was carried out, especially in low endemic areas or in hilly and mountainous regions. Therefore, more attention should be paid to those egg-negative but worm-positive patients with the aim of final elimination of S. japonicum in China.

Evidence for an important role of host microRNAs in regulating hepatic fibrosis in humans infected with Schistosoma japonicum

MicroRNAs (miRNAs) are short, non-coding RNAs that repress the translation of target gene transcripts. They have been implicated in various activities such as cell proliferation, survival, differentiation, migration and metabolism. We report here the first known miRNome and transcriptome analysis of human livers displaying advanced fibrosis due to Schistosoma japonicum infection. We present evidence that hsa-miR-150-5p, hsa-miR-10a-5p, hsa-miR-199a-3p, hsa-miR-4521, hsa-miR-222/221, hsa-miR-663b and hsa-miR-143-3p (associated without correction) play an important role in hepatic fibrosis by acting on metabolism, organization of the extracellular matrix proteins, lipid mobilization and limitation of oxidative damage stress.

Inhibition of Notch Signaling Attenuates Schistosomiasis Hepatic Fibrosis via Blocking Macrophage M2 Polarization

Macrophages play a key role in the pathogenesis of liver granuloma and fibrosis in schistosomiasis. However, the underlying mechanisms have not been fully characterized. This study revealed that the macrophages infiltrating the liver tissues in a murine model of Schistosoma japonica infection exhibited M2 functional polarization, and Notch1/Jagged1 signaling was significantly upregulated in the M2 polarized macrophages in vivo and in vitro. Furthermore, the blockade of Notch signaling pathway by a γ-secretase inhibitor could reverse macrophage M2 polarization in vitro and alleviate liver granuloma and fibrosis in the murine model of schistosomiasis. These results implied that the Notch1/Jagged1 signaling-dependent M2 polarization of macrophages might play an important role in liver granuloma and fibrosis in schistosomiasis, and the inhibition of Notch1/Jagged1 signaling might provide a novel therapeutic approach to administrate patients with schistosomiasis.

Blockade of PD-1 Signaling Enhances Th2 Cell Responses and Aggravates Liver Immunopathology in Mice with Schistosomiasis japonica

Background

More than 220 million people worldwide are chronically infected with schistosomes, causing severe disease or even death. The major pathological damage occurring in schistosomiasis is attributable to the granulomatous inflammatory response and liver fibrosis induced by schistosome eggs. The inflammatory response is tightly controlled and parallels immunosuppressive regulation, constantly maintaining immune homeostasis and limiting excessive immunopathologic damage in important host organs. It is well known that the activation of programmed death 1 (PD-1) signaling causes a significant suppression of T cell function. However, the roles of PD-1 signaling in modulating CD4⁺ T cell responses and immunopathology during schistosome infection, have yet to be defined.

Methodology/Principal Findings

Here, we show that PD-1 is upregulated in CD4⁺ T cells in Schistosoma japonicum (S. japonicum)-infected patients. We also show the upregulation of PD-1 expression in CD4⁺ T cells in the spleens, mesenteric lymph nodes, and livers of mice with S. japonicum infection. Finally, we found that the blockade of PD-1 signaling enhanced CD4⁺ T helper 2 (Th2) cell responses and led to more severe liver immunopathology in mice with S. japonicum infection, without a reduction of egg production or deposition in the host liver.

Conclusions/Significance

Overall, our study suggests that PD-1 signaling is specifically induced to control Th2-associated inflammatory responses during schistosome infection and is beneficial to the development of PD-1-based control of liver immunopathology.

Schistosomiasis is a parasitic disease that affects approximately 220 million people and causes serious morbidity and economic problems mainly in (sub)tropical regions. After Schistosoma japonicum or Schistosoma mansoni infection, parasite eggs are trapped in host liver and induce liver inflammation and fibrosis, leading to irreversible impairment of the liver, and even death of the host. Meanwhile, schistosomes also induce strong regulatory mechanisms to suppress inflammation and prevent excessive immunopathology. Considering it is well known that PD-1 plays a critical role in suppressing T cell function, understanding the role of PD-1 in modulating immune responses during schistosome infection is necessary for the development of PD-1-based control of liver damage in schistosomiasis. Here, increased PD-1 expression in CD4⁺ T cells from both humans and mice with schistosome infection was shown. We further showed that PD-1 blockade preferentially augmented Th2 cell responses and ultimately resulted in more severe liver immunopathology in mice with Schistosomiasis japonica, suggesting that PD-1 signaling is beneficial to further explore therapeutic possibilities for preventing the excessive liver immunopathology.

Colonic High-grade Tubular Adenomas Associated with Schistosoma japonicum

We reported a case of sigmoid colonic high grade tubular adenomas associated with deposited ova of Schistosoma japonicum. A 76-year-old Japanese man was referred to our colonoscopy due to a positive fecal occult blood test. He had a medical history of schistosomiasis japonica. The colonoscopy revealed that there were two sigmoid colon polyps, approximately 8 mm in diameter. These were removed by endoscopic mucosal resection (EMR). Pathological examination revealed high grade tubular adenomas and deposited some ova of Schistosoma japonicum with severe fibrotic change and granuloma formation in the submucosal layer. Colonic schistosomiasis is a probable independent risk factor for the development of colorectal carcinogenesis.

FOXP3+ Regulatory T Cells in Hepatic Fibrosis and Splenomegaly Caused by Schistosoma japonicum: The Spleen May Be a Major Source of Tregs in Subjects with Splenomegaly

Schistosoma eggs cause chronic liver inflammation and a complex disease characterized by hepatic fibrosis (HF) and splenomegaly (SplM). FOXP3+ Tregs could regulate inflammation, but it is unclear where these cells are produced and what roles they play in human schistosomiasis. We investigated blood and spleen FOXP3+ Tregs in Chinese fishermen with lifelong exposure to Schistosoma japonicum and various degrees of liver and spleen disease. FOXP3+ Tregs accounted for 4.3% of CD4+ T cells and 41.2% of FOXP3+CD4+ T cells; they could be divided into CD45RA-FOXP3hi effector (eTregs) and CD45RA+FOXP3low naive Tregs. Blood Treg levels were high in severe HF (+1.3; p = 0.004) and in SplM (+1.03, p = 0.03). Multivariate regression showed that severe HF (+0.85, p = 0.01) and SplM (+0.97; p = 0.05) were independently associated with the higher proportion of Tregs in the blood. This effect was mostly due to an increase in the proportion of eTregs in the blood of HF+++ (+0.9%; p = 0.04) and SplM (+0.9%; p = 0.04) patients. The proportion of eTregs expressing CXCR3 in the blood was lower in the HF+++ patients (37.4 +/- 5.9%) than in those with milder fibrosis (51.7 ± 2%; p = 0.009), whereas proportion were similar for cells expressing CD25hi, CCR7, and CTLA-4. Splenectomy improves symptoms and was associated with decreases in blood FOXP3+ Treg (-2.5; p<0.001) and eTreg (-1.3; p = 0.03) levels. SplM spleens contained a high proportion of eTregs with CXCR3, CCR5 and CTLA4 upregulation and CCR7 downregulation. This, and the strong expression of ligands of CXCR3 and CCR5 in the liver (n = 8) but not in the spleen suggested that spleen eTregs migrated to Th1-infiltrated liver tissues. Such migration may be attenuated in hepatosplenic patients due to lower levels of CXCR3 expression on Tregs (p = 0.009). Thus, higher blood Treg levels are associated with severe liver disease and splenomegaly. Our data are consistent with the hypothesis that the spleen is a major source of Tregs in subjects with splenomegaly. In most cases, Tregs migrate to the Th1-infiltrated liver and the lower levels of CXCR3+ Tregs in the blood of patients with severe schistosomiasis suggest that decreases in Treg migration sites of inflammation may aggravate the disease.

GdCl3 Attenuates Schistosomiasis japonicum Egg-Induced Granulomatosis Accompanied by Decreased Macrophage Infiltration in Murine Liver

Early-stage hepatic granuloma and advanced-stage fibrosis are important characteristics of schistosomiasis. The direct consequences of gadolinium chloride (GdCl₃) in egg-induced granuloma formation have not been reported, although GdCl₃ is known to block the macrophages. In present study, mice were infected with 15 Schistosoma japonicum (S. japonicum) cercariae and treated with GdCl₃ (10 mg/kg body weight) twice weekly from day 21 to day 42 post-infection during the onset of egg-laying towards early granuloma formation. Histochemical staining showed that repeated injection of GdCl₃ decreased macrophages infiltration in liver of mice infected with S. japonicum. Macrophage depletion by GdCl₃ during the initial phase attenuated liver pathological injury characterized by smaller granuloma size and decreased immune inflammation as well as less fibrogenesis. In addition, IL-13Rα2 expression was reduced by GdCl₃ in liver of mice infected with S. japonicum. The results suggest that GdCl₃ depleted macrophages, which attenuated helminth infected immune responses involving with IL-13Rα2 signal. These findings would highlight a therapeutic potential via manipulating IL-13Rα2+ macrophage in schistosomiasis.

[Distribution characteristics of deposited eggs and pathological changes in viscera of New Zealand white rabbits infected with Schistosoma japonicum at different time]

OBJECTIVE

To study the distribution characteristics of deposited eggs and pathological changes in the viscera of animal infected with Schistosoma japonicum at different time.

METHODS

New Zealand white rabbits were infected artificially with quantitative S. japonicum miracidia, then the distribution characteristics and the hatchability of schistosome eggs as well as the pathological changes of the corresponding viscera of the rabbits 42 and 60 d post-infection were observed and compared.

RESULTS

On the 42nd day post-infection, among all the viscera observed, the percentage of eggs deposited, the number of eggs per gram and the hatchability were the highest in the liver, while on the 60th day post-infection, the tissues and organs with the highest values of the above 3 indexes were the liver, rectum and upper section of the small intestine, respectively. From 42 day to 60 day post-infection, the liver of infected rabbits became swelling, hardening and lost elasticity, the color changed from black to dark grey, and egg nodules gradually appeared in the different sections of the small intestine, and also the mucosal hyperemia, edema and egg nodules were seen in the colon, cecum and rectum. The lesion levels tended to be correlated with the deposition of eggs.

CONCLUSION

The amount and the density as well as the hatching rate of deposited eggs of S. japonicum in the viscera of infected rabbits at different time are different, and the lesion level in the host is correlated with the deposition of eggs.

Activation of nuclear factor kappa B in the hepatic stellate cells of mice with schistosomiasis japonica

Schistosomiasis japonica is a serious tropical parasitic disease in humans, which causes inflammation and fibrosis of the liver. Hepatic stellate cells (HSCs) are known to play an important role in schistosome-induced fibrosis, but their role in schistosome-induced inflammation is still largely unknown. Here, we use a murine model of schistosomiasis japonica to investigate the role that nuclear factor kappa B (NF-κB), a critical mediator of inflammatory responses, plays in schistosome-induced inflammation. We revealed that NF-κB was significantly activated in HSCs at the early stage of infection, but not at later stages. We also show that the expression levels of several chemokines regulated by NF-κB signaling (Ccl2, Ccl3 and Ccl5) were similarly elevated at early infection. TLR4 signaling, one of the strongest known inducers of NF-κB activation, seemed not activated in HSCs post-infection. Importantly, we found that levels of miR-146 (a known negative regulator of NF-κB signaling) in HSCs opposed those of NF-κB signaling, elevating at later stage of infection. These results indicate that HSCs might play an important role in the progression of hepatic schistosomiasis japonica by linking liver inflammation to fibrosis via NF-κB signaling. Moreover, our work suggests that miR-146 appeared to regulate this process. These findings are significant and imply that manipulating the function of HSCs by targeting either NF-κB signaling or miR-146 expression may provide a novel method of treating hepatic schistosomiasis japonica.

A boswellic acid-containing extract ameliorates schistosomiasis liver granuloma and fibrosis through regulating NF-κB signaling in mice

Boswellic acid (BA)-containing extracts such as BSE have anti-inflammatory and immunomodulatory activity. In chronic schistosomiasis, the hepatic granuloma and fibrosis induced by egg deposition in the liver is the most serious pathological manifestations. However, little is known regarding the role of BAs in Schistosoma japonicum (S. japonicum) egg-induced liver granuloma and fibrosis. In order to investigate the effect of a water-soluble complex preparation of BSE, BSE-CD, on S. japonicum egg-induced liver pathology, liver granuloma and fibrosis were induced by infecting C57BL/6 mice with 18-22 cercariae of S. japonicum. S. japonicum cercariae infected mice were injected with BSE-CD at the onset of egg granuloma formation (early phase BSE-CD treatment after 4 weeks infection) or after the formation of liver fibrosis (late phase BSE-CD treatment after 7 weeks infection). Our data show that treatment of infected mice with BSE-CD significantly reduced both the extent of hepatic granuloma and fibrosis. Consistent with an inhibition of NF-κB signaling as evidenced by reduced IκB kinase (IKK) activation, the mRNA expression of VEGF (vascular endothelial growth factor, VEGF), TNF-α (tumor necrosis factor-alpha TNF-α) and MCP-1 (monocyte chemotactic protein 1, MCP-1) was decreased. Moreover, immunohistochemical analysis (IHC) revealed that the content of α-SMA in liver tissue of BSE-CD treated mice was dramatically decreased. Our findings suggest that BSE-CD treatment attenuates S. japonicum egg-induced hepatic granulomas and fibrosis, at least partly due to reduced NF-κB signaling and the subsequently decreased expression of VEGF, TNF-α, and MCP-1. Suppression of the activation of hepatic stellate cells (HSC) may also be involved in the therapeutic efficacy of BSE-CD.

Upregulation of cannabinoid receptor-1 and fibrotic activation of mouse hepatic stellate cells during Schistosoma J. infection: role of NADPH oxidase

The endocannabinoid system (CS) has been implicated in the development of hepatic fibrosis such as schistosomiasis-associated liver fibrosis (SSLF). However, the mechanisms mediating the action of the CS in hepatic fibrosis are unclear. The present study hypothesized that Schistosoma J. infection upregulates cannabinoid receptor 1 (CB1) due to activation of NADPH oxidase leading to a fibrotic phenotype in hepatic stellate cells (HSCs). The SSLF model was developed by infecting mice with Schistosoma J. cercariae in the skin, and HSCs from control and infected mice were then isolated, cultured, and confirmed by analysis of HSC markers α-SMA and desmin. CB1 significantly increased in HSCs isolated from mice with SSLF, which was accompanied by a greater expression of fibrotic markers α-SMA, collagen I, and TIMP-1. CB1 upregulation and enhanced fibrotic changes were also observed in normal HSCs treated with soluble egg antigen (SEA) from Schistosoma J. Electron spin resonance (ESR) analysis further demonstrated that superoxide (O2(-)) production was increased in infected HSCs or normal HSCs stimulated with SEA. Both Nox4 and Nox1 siRNA prevented SEA-induced upregulation of CB1, α-SMA, collagen I, and TIMP-1 by inhibition of O2(-) production, while CB1 siRNA blocked SEA-induced fibrotic changes without effect on O2(-) production in these HSCs. Taken together, these data suggest that the fibrotic activation of HSCs on Schistosoma J. infection or SEA stimulation is associated with NADPH oxidase-mediated redox regulation of CB1 expression, which may be a triggering mechanism for SSLF.

Follicular helper T cells promote liver pathology in mice during Schistosoma japonicum infection

Following Schistosoma japonicum (S. japonicum) infection, granulomatous responses are induced by parasite eggs trapped in host organs, particular in the liver, during the acute stage of disease. While excessive liver granulomatous responses can lead to more severe fibrosis and circulatory impairment in chronically infected host. However, the exact mechanism of hepatic granuloma formation has remained obscure. In this study, we for the first time showed that follicular helper T (Tfh) cells are recruited to the liver to upregulate hepatic granuloma formation and liver injury in S. japonicum-infected mice, and identified a novel function of macrophages in Tfh cell induction. In addition, our results showed that the generation of Tfh cells driven by macrophages is dependent on cell–cell contact and the level of inducible costimulator ligand (ICOSL) on macrophages which is regulated by CD40–CD40L signaling. Our findings uncovered a previously unappreciated role for Tfh cells in liver pathology caused by S. japonicum infection in mice.

Schistosomiasis is a chronic helminthic disease that affects approximately 200 million people. After S. japonicum infection, parasite eggs are trapped in host liver and granulomas are induced to form around eggs. Severe granuloma subsequently results in serious liver fibrosis and circulatory impairment chronically. It is important to fully elucidate the mechanism of the granuloma formation. Here, we show that Tfh cells play a novel role of promoting the hepatic granuloma formation and liver injury, and identified a novel function of macrophages in Tfh cells induction in S. japonicum-infected mouse model. In addition, we show that the generation of Tfh cells driven by macrophages is cell–cell contact dependent and regulated by CD40-CD40L signaling. Our findings revealed a novel role and mechanism of macrophages in Tfh cell generation and the liver pathogenesis in S. japonicum-infected mouse model.

[A case of previous infection with schistosomiasis japonica diagnosed holistically on the basis of various clinical examination findings]

A 66-year-old male was referred to our hospital because of a high CRP level. CT and MRI revealed cord-like contrast effects along the periphery of the liver, and peripheral portal vein occlusion was suspected. Histopathological analysis revealed fibrotic occlusion and eosinophil and histiocytic infiltration of the portal vein. Taking into account various clinical imaging tests, blood tests, and histopathological tests and of his current clinical history, he was diagnosed with previous infection of schistosomiasis japonica. We believe that this case illustrates the importance of a comprehensive diagnosis; in addition, we implemented real-time virtual sonography and EOB-MRI that provided useful visual information.

[Therapeutic effect of resveratrol as well as resveratrol combined with praziquantel on the liver fibrosis due to Schistosoma japonicum infection in mice]

OBJECTIVE

To study the therapeutical effect and mechanisms of resveratrol and its combination with praziquantel on the liver fibrosis due to Schistosoma japonicum infection.

METHODS

Eighty mice infected with 25 S. japonicum cercariae for 6 weeks were randomly divided into four groups named as praziquantel group (A), resveratrol group (B), resveratrol+praziquantel group (C) and infection group (D). Mice in groups A and B were treated with praziquantel [500 mg/(kg x d)] for 2 d, and resveratrol [20 mg/(kg x d)] for 6 weeks, respectively. Mice in group C were treated with resveratrol [20 mg/(kg x d)] for 6 weeks after praziquantel treatment [500 mg/(kg x d)x 2 d]. Group D served as infection control. Twenty normal mice were taken as normal control group (Group E). At the 12th week post-infection, all mice were sacrificed and the liver tissues were removed. Histopathological changes were observed in the liver of all groups. RT-PCR was used to detect the relative VEGF mRNA level in liver tissue. Maleic dialdehyde (MDA) content and superoxide dismutase (SOD) activity in liver were measured by ELISA. The expressions of VEGF, type I and type III collagen were examined by immunohistochemistry.

RESULTS

After treatment, the degrees of liver fibrosis in groups A, B and C decreased. The hepatic expression of VEGF mRNA and VEGF protein levels in groups A (0.37 +/- 0.06, 0.69 +/- 0.42), B (0.23 +/- 0.01, 0.38 +/- 0.42), C (0.11 +/- 0.00, 0.12 +/- 0.17) and E (0.06 +/- 0.03, 0.04 +/- 0.02) were lower than that of group D (0.60 +/- 0.03, 0.97 +/- 0.36) (P < 0.01), those in groups A and B were significantly lower than that of group C (P < 0.01 or P < 0.05), and those in group A were lower than in group B (P < 0.05). There was no significant difference in liver SOD activity and MDA content between group A(13.56 +/- 2.56, 7.62 +/- 2.30) and group B(14.28 +/- 1.56, 6.63 +/- 2.31)(P > 0.05). Compared with group C (22.36 +/- 1.55, 2.31 +/- 1.31), mice in groups A and B exhibited decreased an SOD activity, but increased MDA content (P < 0.05). SOD activity of groups A, B, and C was higher than that of group D (P < 0.05 or P < 0.01), and MDA content in the above three groups was lower than that of group D (P < 0.05 or P < 0.01).

CONCLUSION

Resveratrol has an antifibrogenic effect through inhibiting the expression of VEGF and reducing oxidative stress in mice with Schistosoma japonicum egg-induced liver fibrosis. Resveratrol and praziquantel show a synergistic action in antifibrosis treatment.

[Effect of immune response mediated by ICOS signaling pathway on hepatic fibrosis in mice infected with Schistosoma japonicum]

OBJECTIVE

To investigate the effect of Th2 polarization mediated by ICOS signaling pathway on hepatic fibrosis in mice infected with Schistosoma japonicum.

METHODS

ICOS transgenic (ICOS-Tg) mice and wild-type FVB/NJ mice were used as experimental schistosomiasis model. The sera, livers and spleen lymphocytes of mice were collected, and spleen lymphocytes were stimulated with SEA for 72 h on the day before infection (0 week), and at 4, 7, 12, 16 and 20 weeks post-infection. The concentrations of Th1 cytokines (IFN-gamma and IL-12) and Th2 cytokines (IL-4 and IL-13) in the culture supernatants were measured with sandwich ELISA kit. The levels of SEA-specific antibodies of IgG and its subtypes (IgG1 and IgG2a) in mice sera were measured by ELISA. The concentrations of hyaluronic acid (HA) and hydroxyproline (HYP) in mice sera were measured with sandwich ELISA kit. The expression of alpha-SMA, TGF-beta1 and collagen-I in livers from ICOS-Tg/wild-type mice were assessed by immunohistochemical staining. Liver granulomatous pathology and fibrosis level in ICOS-Tg/wild-type mice was dynamically observed with hematoxylin-eosin (HE) staining and Masson trichrome staining, respectively.

RESULTS

The levels of Th2-type cytokines (IL-4 and IL-13) of ICOS-Tg mice were significantly higher than that of wild-type FVB/NJ mice on 7, 12, 16, and 20 weeks post-infection (P < 0.05). However, Th1 cytokines IFN-gamma and IL-12 showed no significant difference between the two groups (P > 0.05). Th2 differentiation index of ICOS-Tg mice was significantly higher than that of wild-type mice on 7, 12, 16 and 20 weeks post-infection (P < 0.05 or P < 0.01). Compared with wild-type mice, the levels of SEA-specific antibodies of IgG and its subtypes (IgG1 and IgG2a) in ICOS-Tg mice increased significantly (P < 0.05 or P < 0.01, except IgG on 4 and 7 weeks post-infection). Moreover, the ratio of IgG1/IgG2a in ICOS-Tg mice (5.75 +/- 0.94, 4.96 +/- 0.98) were significantly higher than that of wild-type mice (4.31 +/- 0.81, 3.41 +/- 0.83) on 12 and 16 weeks post-infection (P < 0.05). The levels of HA on 7, 12, 16, and 20 weeks post-infection (P < 0.05 or P < 0.01) and HYP on 12, 16, and 20 weeks post-infection (P < 0.05) in ICOS-Tg mice were significantly higher than that of wild-type mice. Immunohistochemical staining showed, from 7 to 20 weeks post-infection, alpha-SMA and TGF-beta1 expression in liver of ICOS-Tg mice was significantly higher than that of wild-type mice (P < 0.05 or P < 0.01); collagen-I level was also higher than wild-type mice. However, there was a significant difference in collagen-I level between the two groups on 20 weeks post-infection (P < 0.05). Furthermore, HE staining showed, on 7, 12, and 16 weeks post-infection, single-egg granuloma volume of ICOS-Tg mice [(28.72 +/- 6.68) x 10(6), (20.47 +/- 5.09) x 10(6) and (12.77 +/- 4.86) x 10(6) microm 3] was significantly higher than that of wild-type mice [(18.04 +/- 6.21) x 10(6), (15.28 +/- 4.87) x 10(6) and (11.24 +/- 4.38) x 10(6) microm 3]. Masson staining showed that level of hepatic fibrosis in ICOS-Tg mice were higher than that of wild-type mice, but the fibrosis scores showed no statistically significant difference between the two groups (P > 0.05).

CONCLUSION

Th2 immune response is up-regulated in ICOS-Tg mice infected with S. japonicum, and the degree of hepatic fibrosis and related indicators increase. These findings suggest that Th2 polarization mediated by ICOS signaling plays a role in hepatic fibrosis formation in mice infected with S. japonicum.

[Study of closed colony of Microtus fortis infected with Schistosoma japonicum]

OBJECTIVE

To understand the pathological changes of tissues and organs in Microtus fortis infected with Schistosoma japonicum for further insight into the biological dynamic variation and explore immune mechanisms of M. fortis against S. japonicum infection.

METHODS

The healthy M. fortis and mouse were infected with cercariae of S. japonicum through abdominal skin. On the day 12, 20 and 40, the M. fortis and mouse were sacrificed by cervical dislocation and dissected. The liver and kidney slices of M. fortis and mouse of the different groups were prepared and stained with hematoxylin eosin stain (HE) by conventional techniques, respectively.

RESULTS

We did not find obvious lesions on the internal organs of mouse 12 d and 20 d after the infection and the lesions of M. fortis 40 d after the infection. However, white nodules appeared on the liver, kidney and spleen of the M. fortis 12 d and 20 d after the infection, and there were a lot of S. japonicum worms on pathological sections of inflamed liver and kidney tissues, and the boundary between worms and normal organization was clear. There were no parasites on pathological section of liver and kidney of mouse 12 d and 20 d after the infection.

CONCLUSION

Among M. fortis, there are severe immune responses and the immune responses have an individual difference 12 days after S. japonicum infection.

[Preliminary observation on the effect of mefloquine against egg granuloma formation in the liver of mice infected with Schistosoma japonicum]

OBJECTIVE

To explore whether mefloquine possesses the effect on granuloma formation induced by Schistosoma japonicum eggs.

METHODS

Seventeen out of twenty-eight mice infected with 20 S. japonicum cercariae for 35 days were treated orally with mefloquine at a single dose of 200 mg/kg, and groups of 2-3 mice were sacrificed at various intervals post-treatment. The livers removed from each group of mice were fixed in 10% formaldehyde. While the remained 11 untreated mice divided into 6 groups (1-2 mice per group) were sacrificed at the same time periods as groups of mice treated with mefloquine, and their livers served as untreated corresponding controls. The granulomas with single egg in the center were counted and their diameters were measured using an ocular micrometer. The liver tissue sections were stained with hematoxylin and eosin (HE), Foot's or Mallory's methods for observation on histopathological alteration of egg granulomas, and on the appearance of reticular and collagen fibers within the granulomas.

RESULTS

After infected mice were treated with mefloquine for 3, 7, 14, 21, 28 and 35 days, i.e., 38, 42, 49, 56, 63, and 70 days post-infection, the mean diameters of granuloma with single egg measured in the liver tissues section were (161 +/- 19), (175 +/- 13), (195 +/- 9), (171 +/- 40), (180 +/- 13), and (145 +/- 25) microm, respectively, and each of them was significantly lower than that of its corresponding control group of (189 +/- 18), (197 +/- 11), (211 +/- 12), (208 +/- 19), (203 +/- 16), and (207 +/- 36) microm (P < 0.01 or P < 0.05). Histopathological observation showed that in mice treated with mefloquine, the eosinophil-predominant inflammatory cells around the egg granuloma were sustained to 14-21 d post treatment (49-56 d post infection), which was significantly different from the corresponding control groups that all the eggs were surrounded by fibroblasts at 42 d post infection. Up to 28-35 d post treatment (63-70 d post infection), the boundary of egg granulomas distributed in the liver tissues of mefloquine treated groups was nearer in comparison to the corresponding control groups. Further observation on the reticular and collagen fibers within the egg granulomas by using specially staining methods demonstrated that in groups of mice treated with mefloquine for 2 weeks, the emergence and amount of the two kinds of fibers were delayed and less in comparison with corresponding control groups. After infected mice treated with mefloquine for 21 d (56 d post infection), the amount of the two kinds of fibers revealed in some egg granulomas was similar to the corresponding control group, but no further increase in the amount of the fibers, and seldom spread over the boundary of egg granuloma were seen 28 d and 35 d after treatment (63 d and 60 d post infection). While in corresponding control groups, the two kinds of fibers increased continuously with time post infection to become thick, and spread over the boundary of granuloma to further interconnect with the fibers stretched from the adjacent granuloma, and separate the liver tissue to form the grid-like structure.

CONCLUSION

Preliminary observation demonstrates that mefloquine possesses suppressive effect on granuloma formation induced by S. japonicum eggs.

[Expression of Smad proteins in the process of liver fibrosis in mice infected with Schistosoma japonicum]

OBJECTIVE

To study the expression of Smads proteins involved in TGF-beta1 signal transduction during the process of liver fibrosis in BALB/c mice infected with Schistosoma japonicum.

METHODS

Thirty-four BALB/c mice were each infected with (20 +/- 1) S. japonicum cercariae. The mice were sacrificed at 8, 12, 16 and 24 weeks postinfection. Ten healthy BALB/c mice served as normal control group. The liver tissues were fixed in 10% formaldehyde for histology and immunohistochemistry assay. The single-egg granuloma area was measured in hematoxylin-eosin stain section. The degree of liver fibrosis was determined by Sirius red staining. Immunohistochemistry was used to observe the expression of Smad protein.

RESULTS

The area of single-egg granuloma peaked at 8th week post-infection [(533 +/- 1.03) mm2], and with time passing, the area diminished, and the area of granuloma reduced to (2.94 +/- 1.69) mm2 at 24 weeks post-infection. The difference was significant among the 4 periods after infection in single-egg granuloma area (P < 0.05). Collagen fibers appeared around granulomas at 8 weeks (2.03 +/- 0.52) and increased gradually. At 24 weeks post-infection, the degree of liver fibrosis reached a peak (6.90 +/- 1.57), and the liver fibrosis degree was significantly different among infection groups (P < 0.05). Immunohistochemistry showed low expression level of Smad2/3 and Smad7 and inconspicuous level of Smad4 in livers of the normal mice. The expression of Smad2/3 was found mostly in the cytoplasm and nucleus of cells around granulomas at 8th week post-infection, and the positive area of Smad2/3 was (7.24 +/- 1.64)% by semi-quantity. At 12 weeks post-infection, the Smad2/3 protein expression level around granulomas and liver sinus reached the peak [(10.01 +/- l.07)%], and there was significant difference between infection groups and the control [(2.13 +/- 0.32)%]. A significant difference in the Smad2/3 protein expression level was found between 12 weeks post-infection group and 8 weeks or 16 weeks post-infection groups. The expression level of Smad4 was (8.81 +/- 1.13)% at 8th week post-infection, higher than that in the control [(4.83 +/- 1.15)%] (P < 0.05). There was no difference among the infected mice at different periods in the level of Smad4 (P > 0.05). After 8 weeks post infection, Smad7 protein sparsely appeared around the granuloma [(4.15 +/- 1.26)%] while it disappeared around liver sinus. At 12 weeks post-infection, the level of Smad7 protein was higher [(6.34 +/- 1.5)%], but with prolonged infection time, no significant difference was revealed (P > 0.05). The level of Smad7 in infected mice was higher than that in the control (P < 0.05).

CONCLUSION

Resylts show high expression for Smad2/3 and Smad7 and low expression level of Smad4 during the process of liver fibrosis in BALB/c mice infected with Schistosoma japonicum.

Exogenous bone morphogenetic protein-7 reduces hepatic fibrosis in Schistosoma japonicum-infected mice via transforming growth factor-β/Smad signaling

AIM: To investigate the antifibrotic effects of bone morphogenetic protein-7 (BMP-7) on Schistosoma japonicum (S. japonicum)-induced hepatic fibrosis in BALB/C mice.

METHODS: Sixty BALB/C mice were randomly divided into three groups, including a control group (group A, n = 20), model group (group B, n = 20) and BMP-7 treated group (group C, n = 20). The mice in group B and group C were abdominally infected with S. japonicum cercariae to induce a schistosomal hepatic fibrosis model. The mice in group C were administered human recombinant BMP-7. Liver samples were extracted from mice sacrificed at 9 and 15 wk after modeling. Hepatic histopathological changes were assessed using Masson’s staining. Transforming growth factor-beta 1 (TGF-β1), alpha-smooth muscle actin (α-SMA), phosphorylated Smad2/3 (pSmad2/3) and Smad7 protein levels and localization were measured by Western blotting and immunohistochemistry, respectively, and their mRNA expressions were detected by reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS: The schistosomal hepatic fibrosis mouse model was successfully established, as the livers of mice in group B and group C showed varying degrees of typical schistosomal hepatopathologic changes such as egg granuloma and collagen deposition. The degree of collagen deposition in group C was higher than that in group A (week 9: 22.95 ± 6.66 vs 2.02 ± 0.76; week 15: 12.84 ± 4.36 vs 1.74 ± 0.80; P < 0.05), but significantly lower than that in group B (week 9: 22.95 ± 6.66 vs 34.43 ± 6.96; week 15: 12.84 ± 4.36 vs 18.90 ± 5.07; P < 0.05) at both time points. According to immunohistochemistry data, the expressions of α-SMA, TGF-β1 and pSmad2/3 protein in group C were higher than those in group A (α-SMA: week 9: 21.24 ± 5.73 vs 0.33 ± 0.20; week 15: 12.42 ± 4.88 vs 0.34 ± 0.27; TGF-β1: week 9: 37.00 ± 13.74 vs 3.73 ± 2.14; week 15: 16.71 ± 9.80 vs 3.08 ± 2.35; pSmad2/3: week 9: 12.92 ± 4.81 vs 0.83 ± 0.48; week 15: 7.87 ± 4.09 vs 0.90 ± 0.45; P < 0.05), but significantly lower than those in group B (α-SMA: week 9: 21.24 ± 5.73 vs 34.39 ± 5.74; week 15: 12.42 ± 4.88 vs 25.90 ± 7.01; TGF-β1: week 9: 37.00 ± 13.74 vs 55.66 ± 14.88; week 15: 16.71 ± 9.80 vs 37.10 ± 12.51; pSmad2/3: week 9: 12.92 ± 4.81 vs 19.41 ± 6.87; week 15: 7.87 ± 4.09 vs 13.00 ± 4.98; P < 0.05) at both time points; the expression of Smad7 protein in group B was higher than that in group A and group C at week 9 (8.46 ± 3.95 vs 1.00 ± 0.40 and 8.46 ± 3.95 vs 0.77 ± 0.42; P < 0.05), while there were no differences in Smad7 expression between the three groups at week 15 (1.09 ± 0.38 vs 0.97 ± 0.42 vs 0.89 ± 0.39; P > 0.05). Although minor discrepancies were observed, the results of RT-PCR and Western blotting were mainly consistent with the immunohistochemical results.

CONCLUSION: Exogenous BMP-7 significantly decreased the degree of hepatic fibrosis in both the acute and chronic stages of hepato-schistosomiasis, and the regulatory mechanism may involve the TGF-β/Smad signaling pathway.

Schistosoma japonicum egg antigen up-regulates fibrogenesis and inhibits proliferation in primary hepatic stellate cells in a concentration-dependent manner

AIM: To investigate the effects of different concentrations of Schistosoma japonicum (S. japonicum) egg antigen on fibrogenesis and apoptosis in primary hepatic stellate cells (HSCs).

METHODS: A mouse model of schistosomiasis-associated liver fibrosis (SSLF) was established by infecting mice with schistosomal cercaria via the abdomen. HSCs were isolated from SSLF mice by discontinuous density gradient centrifugation, and their identity was confirmed by immunofluorescence double staining of α-smooth muscle actin (α-SMA) and desmin. The growth inhibitory effect and 50% inhibitory concentration (IC50) of S. japonicum egg antigen for primary HSCs (24 h) were determined using a cell counting kit-8 (CCK-8) assay. The expression levels of α-SMA, matrix metalloproteinase-9 (MMOL/LP-9) and tissue inhibitor of metalloproteinases-1 (TIMP-1) in HSCs in response to different concentrations of S. japonicum egg antigen were detected by Western blotting and real-time reverse transcription-polymerase chain reaction. The levels of phospho-P38 (P-P38), phospho-Jun N-terminal kinase (P-JNK) and phospho-Akt (P-AKT) in HSCs were detected by Western blotting.

RESULTS: An SSLF mouse model was established, and primary HSCs were successfully isolated and cultured. S. japonicum egg antigen inhibited HSC proliferation in a concentration-dependent manner. The IC50 of the S. japonicum egg antigen was 244.53 ± 35.26 μg/mL. S. japonicum egg antigen enhanced α-SMA expression at both the mRNA and protein levels and enhanced TIMP-1 expression at the mRNA level in HSCs (P < 0.05), whereas the expression of MMOL/LP-9 was attenuated at both the mRNA and protein levels in a concentration-dependent manner (P < 0.05). A high concentration of S. japonicum egg antigen enhanced P-P38, P-JNK and P-AKT activation (P < 0.05). The changes in α-SMA and MMOL/LP-9 expression induced by S. japonicum egg antigen were closely correlated with P-P38 and P-JNK activation (P < 0.05). The attenuation of MMOL/LP-9 was also correlated with P-AKT activation (P < 0.05), but the increase in α-SMA expression was not. TIMP-1 expression was not correlated with P-P38, P-JNK or P-AKT activation.

CONCLUSION: S. japonicum egg antigen promotes fibrogenesis, activates the P38/JNK mitogen-activated protein kinase and AKT/PI3K signaling pathways and inhibits proliferation in primary HSCs isolated from SSLF mice in a concentration-dependent manner.

A boswellic acid-containing extract attenuates hepatic granuloma in C57BL/6 mice infected with Schistosoma japonicum

Granuloma formation has been shown to be induced and elicited by schistosome egg antigens, and it finally develops into fibrosis in intestine and the liver. Hepatic fibrosis is the main cause of increased morbidity and mortality in humans infected with schistosomes. Boswellic acid (BA)-containing extracts such as extracts of the oleogum resin from Boswellia serrata (BSE) have anti-inflammatory and immunomodulatory activity. However, little is known about the role of such extracts in schistosome egg-induced granulomatous inflammation. In order to investigate the effect of a watersoluble cyclodextrin complex preparation of BSE (BSE-CD) on Schistosoma japonicum (S. japonicum) egg-induced liver granuloma, mice infected with S. japonicum cercariae were injected with BSE-CD during egg granuloma formation. The data showed that BSE-CD significantly reduced the size of liver granuloma and levels of serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST); however, BSE-CD treatment had no effect on worm load and egg burden. The data also showed that BSE-CD significantly decreased the expression of leukotriene B(4) (LTB(4)) and prostaglandin E(2) (PGE(2)), as well as the expression of matrix metallopeptidase 9 (MMP-9) in liver both on the mRNA and protein level. Thus, BSE-CD can significantly attenuate S. japonicum egg-induced hepatic granuloma, which may be partly dependent on the downregulation of some biochemical mediators.

The sources and metabolic dynamics of Schistosoma japonicum DNA in serum of the host

The polymerase chain reaction (PCR) assay has turned out to be one of the most potential tools for diagnosis of schistosomiasis. However, the source and metabolic dynamics of Schistosoma japonicum DNA in the blood of hosts is not clear. In this study, rabbit models with monosexual and mixed sexual cercariae infection were established to interpret the source of the parasite DNA in serum of the hosts. Following administration of praziquantel at 7 weeks postinfection, the metabolic mechanism of S. japonicum DNA in serum of the hosts was studied. The findings showed that, for the monosexual cercariae infection, the parasite DNA was detectable in serum of the host from day 3 to week 3 postinfection, while for the mixed sexual cercariae infection, the detection results were continually positive during the 7 weeks after infection. After treatment with praziquantel, detection of S. japonicum DNA in rabbit sera became positive at the second day posttreatment, and the positive period lasted 3 weeks in the monosexual cercariae infection group. However, with the mixed sexual cercariae infection group, the PCR results remained positive for 16 weeks after treatment. We conclude that the S. japonicum DNA in host serum primarily comes from the residual body of dead schistosomula and/or tegument shedding of worm growing in the first 4 weeks postinfection, while during the spawning stage of the female schistosome, the parasite DNA mainly comes from the disintegration of inactive eggs. The duration from treatment to total elimination of worm origin DNA in serum is not exceeding 3 weeks. However, the DNA release from inactive eggs can last for more than 16 weeks. Further studies are needed to address the sources and metabolic dynamics of S. japonicum DNA in human serum.

[Comparison of collagen fiber staining between Van-Gieson staining and Masson trichrome staining of hepatic specimens in mice with Schistosoma japonicum infection]

OBJECTIVE

To compare the effects of collagen fiber staining between Van-Gieson staining and Masson trichrome staining of hepatic specimens in mice with Schistosoma japonicum infection.

METHODS

A model of hepatic granuloma and fibrosis was established by infecting mice with S. japonicum cercariae, then the hepatic specimens were taken and Van-Gieson staining and Masson trichrome staining were performed. Eventually, the area of granuloma and fibrosis were measured by imaging analysis software.

RESULTS

When the time of staining was 3-7 min, there was no significant difference of the fibrosis areas between the two methods (P > 0.05); when the time of staining was more than 10 min, the staining area showed by Masson's staining was significantly larger than that showed by Van-Gieson staining, and the difference was statistically significant (P < 0.05).

CONCLUSION

The operation procedures of Van-Gieson staining are simpler and easier to master than those of Masson trichrome staining, therefore Van-Gieson staining is a better method to display collagen.

Comparison of worm development and host immune responses in natural hosts of Schistosoma japonicum, yellow cattle and water buffalo

BACKGROUND

Yellow cattle and water buffalo are two of the most important natural hosts for Schistosoma japonicum in China. Previous observation has revealed that yellow cattle are more suited to the development of S. japonicum than water buffalo. Understanding more about the molecular mechanisms involved in worm development, as well as the pathological and immunological differences between yellow cattle and water buffalo post infection with S japonicum will provide useful information for the vaccine design and its delivery procedure.

RESULTS

The worm length (p < 0.01), worm recovery rate (p < 0.01) and the percentage of paired worms (p < 0.01) were significantly greater in yellow cattle than those in water buffalo. There were many white egg granulomas in the livers of yellow cattle, but fewer were observed in water buffalo at 7 weeks post infection. The livers of infected yellow cattle contained significantly increased accumulation of inflammatory cells, and the schistosome eggs were surrounded with large amounts of eosinophil infiltration. In contrast, no hepatocyte swelling or lymphocyte infiltration, and fewer white blood cells, was observed in water buffalo. The percentage of CD4⁺ T cells was higher in yellow cattle, while the percentage of CD8⁺ T cells was higher in water buffalo from pre-infection to 7 w post infection. The CD4/CD8 ratios were decreased in both species after challenge with schistosomes. Comparing with water buffalo, the IFN-γ level was higher and decreased significantly, while the IL-4 level was lower and increased gradually in yellow cattle from pre-infection to 7 w post infection.

CONCLUSIONS

In this study, we confirmed that yellow cattle were more suited to the development of S. japonicum than water buffalo, and more serious pathological damage was observed in infected yellow cattle. Immunological analysis suggested that CD4⁺ T cells might be an integral component of the immune response and might associate with worm development in yellow cattle. A shift from Th1 to Th2 type polarized immunity was only shown clearly in schistosome-infected yellow cattle, but no shift in water buffalo. The results provide valuable information for increased understanding of host-schistosome interactions, and for control of schistosomiasis.

[Causes of death of advanced schistosomiasis patients in Jiaxing City from 1998 to 2008]

OBJECTIVE

To understand the causes of death of advanced schistosomiasis patients in Jiaxing City from 1998 to 2008, so as to provide the evidence for improving the diagnosis and treatment of advanced schistosomiasis patients.

METHODS

The data of advance schistosomiasis inpatients from April 1998 to March 2008 were collected, analyzed and combined with the following up to understand the epidemic characteristics and the causes of death of advance schistosomiasis patients.

RESULTS

There were 2 004 of advanced schistosomiasis inpatients and 202 patients died. Among the 202 cases, 39.60% of patients were 60-70 years old and 34.65% 70-80 years old. The death causes included upper gastrointestinal hemorrhage (69 cases, 34.16%), hepatic encephalopathy (45 cases, 22.84%), and others.

CONCLUSION

The upper gastrointestinal hemorrhage and hepatic encephalopathy were the main causes of death of advanced schistosomiasis patients in Jiaxing City during the past 10 years.

Polyinosinic-polycytidylic acid attenuates hepatic fibrosis in C57BL/6 mice with Schistosoma japonicum infection

The development of hepatic fibrosis is the principal cause of morbidity and mortality in human beings infected with schistosoma. In this study, we investigated the effect of polyinosinic-polycytidylic acid (poly I:C) on Schistosoma japonicum (S. japonicum) egg-induced liver fibrosis. S. japonicum cercariae infected mice were injected with poly I:C at the onset of egg granuloma formation (early phase poly I:C treatment) or after the formation of liver fibrosis (late phase poly I:C treatment). Our results showed that both early and late phase poly I:C treatment significantly reduced collagen deposition and hepatic stellate cell activation in the liver. Poly I:C is one of the most effective adjuvants for Th1 type responses, and its protective effect on liver fibrosis was accompanied by increased IFN-α, IFN-β, IFN-γ, IL-12, TNF-α, and IL-10 mRNA expression, and decreased IL-4 and IL-5 mRNA expression. Moreover, poly I:C injection also enhanced the mRNA expression of natural killer group 2 member D (NKG2D) and tumor necrosis factor related apoptosis-inducing ligand (TRAIL). Therefore, it is indicated that poly I:C can significantly attenuate S. japonicum egg-induced hepatic fibrosis, which may be partly dependent on the increased Th1 response and decreased Th2 response.

Negative regulation of Schistosoma japonicum egg-induced liver fibrosis by natural killer cells

The role of natural killer (NK) cells in infection-induced liver fibrosis remains obscure. In this study, we elucidated the effect of NK cells on Schistosoma japonicum (S. japonicum) egg-induced liver fibrosis. Liver fibrosis was induced by infecting C57BL/6 mice with 18–20 cercariae of S. japonicum. Anti-ASGM1 antibody was used to deplete NK cells. Toll-like receptor 3 ligand, polyinosinic-polycytidylic acid (poly I∶C) was used to enhance the activation of NK cells. Results showed that NK cells were accumulated and activated after S. japonicum infection, as evidenced by the elevation of CD69 expression and IFN-γ production. Depletion of NK cells markedly enhanced S. japonicum egg-induced liver fibrosis. Administration of poly I∶C further activated NK cells to produce IFN-γ and attenuated S. japonicum egg-induced liver fibrosis. The observed protective effect of poly I∶C on liver fibrosis was diminished through depletion of NK cells. Disruption of IFN-γ gene enhanced liver fibrosis and partially abolished the suppression of liver fibrosis by poly I∶C. Moreover, expression of retinoic acid early inducible 1 (RAE 1), the NKG2D ligand, was detectable at high levels on activated hepatic stellate cells derived from S. japonicum-infected mice, which made them more susceptible to hepatic NK cell killing. In conclusion, our findings suggest that the activated NK cells in the liver after S. japonicum infection negatively regulate egg-induced liver fibrosis via producing IFN-γ, and killing activated stellate cells.

Schistosomiasis continues to be a major public health problem in the developing world. Parasite egg-induced liver fibrosis is the principal cause of morbidity and mortality in human infected with schistosoma. Thus, elucidating the mechanisms that restrict tissue fibrosis may lead to more effective strategies for immunological intervention in this and a variety of chronic diseases. NK cells have been demonstrated to play an important role in suppressing carbon tetrachloride (CCl₄)-induced liver fibrosis. However, little is known about the role of NK cells in an infection-based model of fibrosis. In the current study, we determined, for the first time, the role of NK cells in S. japonicum egg-induced liver fibrosis. Our findings suggest that the activated NK cells in the liver after S. japonicum infection negatively regulate egg-induced liver fibrosis via producing IFN-γ, and killing activated stellate cells. These results further our understanding of the innate immune cells that regulate the development of S. japonicum-induced fibrosis and aid in the development of potential strategies to enhance immunity against this and other chronic inflammatory diseases of the liver where fibrosis is a common feature.

Oral delivery of the Sj23LHD-GST antigen by Salmonella typhimurium type III secretion system protects against Schistosoma japonicum infection in mice

BACKGROUND

Schistosomiasis japonica is a zoonotic parasitic disease and oral vaccine delivery system would be benefit for prevention of this disease. Although attenuated salmonella has been used as an antigen expression vector for oral vaccine development, the membrane-bound vacuoles in which bacteria reside hinders the presentation of expressed heterologous antigens to the major histocompatibility complex (MHC) molecules. The present work used an attenuated Salmonella typhimurium strain VNP20009 to secretory expression of Sj23LHDGST bivalent antigen from Schistosoma japonicum and tested the protective efficacy against S. japonicum infection in orally immunized mice.

METHODOLOGY/PRINCIPAL FINDINGS

Promoters (nirB or pagC) were used to express the antigen (Sj23LHDGST) and the Salmonella type III or α-hemolysin secretion system was employed to secrete it. The immunoblotting analysis and fluorescent microscopy revealed that the antigen was effectively expressed and delivered to the cytosol of macrophages in vitro. Among recombinant vaccine strains, an engineered VNP20009 which expressed the antigen by nirB promoter and secreted it through type III secretion system (nirB-sopE(1-104)-Sj23LHD-GST) efficiently protected against S. japonicum infection in a mouse model. This strain elicited a predominantly IgG(2a) antibody response and a markedly increase in the production of IL-12 and IFN-γ. The flow cytometric analysis demonstrated that this strain caused T cell activation as evidenced by significantly increased expression of CD44 and CD69.

CONCLUSION/SIGNIFICANCE

Oral delivery of antigen by nirB-driven Salmonella typhimurium type III secretion system is a novel, safe, inexpensive, efficient and convenient approach for schistosome vaccine development.

Differential expression of chemokine and matrix re-modelling genes is associated with contrasting schistosome-induced hepatopathology in murine models

The pathological outcomes of schistosomiasis are largely dependent on the molecular and cellular mechanisms of the host immune response. In this study, we investigated the contribution of variations in host gene expression to the contrasting hepatic pathology observed between two inbred mouse strains following Schistosoma japonicum infection. Whole genome microarray analysis was employed in conjunction with histological and immunohistochemical analysis to define and compare the hepatic gene expression profiles and cellular composition associated with the hepatopathology observed in S. japonicum-infected BALB/c and CBA mice. We show that the transcriptional profiles differ significantly between the two mouse strains with high statistical confidence. We identified specific genes correlating with the more severe pathology associated with CBA mice, as well as genes which may confer the milder degree of pathology associated with BALB/c mice. In BALB/c mice, neutrophil genes exhibited striking increases in expression, which coincided with the significantly greater accumulation of neutrophils at granulomatous regions seen in histological sections of hepatic tissue. In contrast, up-regulated expression of the eosinophil chemokine CCL24 in CBA mice paralleled the cellular influx of eosinophils to the hepatic granulomas. Additionally, there was greater down-regulation of genes involved in metabolic processes in CBA mice, reflecting the more pronounced hepatic damage in these mice. Profibrotic genes showed similar levels of expression in both mouse strains, as did genes associated with Th1 and Th2 responses. However, imbalances in expression of matrix metalloproteinases (e.g. MMP12, MMP13) and tissue inhibitors of metalloproteinases (TIMP1) may contribute to the contrasting pathology observed in the two strains. Overall, these results provide a more complete picture of the molecular and cellular mechanisms which govern the pathological outcome of hepatic schistosomiasis. This improved understanding of the immunopathogenesis in the murine model schistosomiasis provides the basis for a better appreciation of the complexities associated with chronic human schistosomiasis.

Schistosomiasis is a significant cause of morbidity and mortality in the tropical world although its true burden has been historically underestimated. Millions of people currently endure severe pathology as a result of schistosome infections, although some individuals appear to be less susceptible to infection despite constant parasite exposure. A similar range of disease susceptibility is evident in different strains of inbred mice infected with schistosomes, thereby mirroring the clinical situation. Granuloma formation in the liver of both humans and mice is a characteristic manifestation of chronic schistosomiasis, and is largely controlled by gene signalling pathways. Certain genes expressed in particular cohorts of mice and humans may be associated with the development of severe pathology, or may confer a protective phenotype. This murine study highlights some key molecular aspects of chronic schistosomiasis which may be responsible for the development of both mild and severe pathology, and provides a bench mark for studying the mechanisms of schistosome-induced disease in humans.

[Destructive effect of eggs of Schistosoma japonicum on spleens in C57BL/6 mice]

OBJECTIVE

To observe the destructive effect of eggs of Schistosomajaponicum on the splenic structure in C57BL/6 mice.

METHODS

The C57BL/6 mice were injected intravenously with eggs of S. japonicum or soluble egg antigen (SEA), or the eggs were injected surgically into the spleens of the mice. Four weeks later, the mice were sacrificed, the splenic paraffin sections were stained with H & E and the splenic structures were observed. Other two groups of mice were infected with single-sex and both sexes of schistosome cercariae, respectively. Nine weeks after the infection, the mice were sacrificed, and the splenic structures were observed and compared among the groups aforementioned.

RESULTS

The splenic structure of mice injected intravenously with eggs were destroyed, and characterized with decreased number of lymphoid follicles and blurred marginal zone. Lymphoid follicles around the eggs injected into the spleen were also seriously depauperated. The splenic weight (0.15 +/- 0.01) g of the mice infected with single-sex cercariae significantly less than that (0.41 +/- 0.03) g of the mice infected with both sexes cercariae (P < 0.01). However, the splenic structure of the mice infected with single-sex cercariae kept integrated.

CONCLUSION

Eggs of S. japonicum have a destructive effect on the splenic structure in C57BL/6 mice.

[Anti-hepatofibrosis effect of fasudil hydrochloride on Schistosoma japonicum-infected mice]

OBJECTIVE

To investigate the anti-fibrotic effect of fasudil hydrochloride on Schistosoma japonicum-infected mice, and the effect of fasudil hydrochloride on hepatic stellate cells (HSCs).

METHODS

Thirty female BALB/c mice were randomly divided into 3 groups viz, normal control group (NC group), infection group, and experiment group. Mice in both infection group and experiment group were infected with (14:2) cercariae of S japonicum. At 6 weeks post infection, mice in experiment group were intraperitoneally injected with fasudil hydrochloride (10 mg/kg) twice a day for 7 d, while mice in NC group and infection group received the same volume of physiological saline. All mice were sacrificed 12 h after the last injection. Livers from NC group and infection group were used to prepare tissue sections for hematoxylin and eosin (HE) staining, or sirius red staining, and observed under light microscope. Livers from all three groups were used to detect content of hydroxyproline (Hyp) and the mRNA expressions of alpha-smooth muscle actin (alpha-SMA), type I collagen alpha1 (Col1alpha1) and epithelial cell transforming sequence 2 (Ect2). HSCs from mice in all three groups were isolated to detect the mRNA levels of alpha-SMA, Col1alpha1, and Ect2, respectively.

RESULTS

Pathological sections showed that in livers from mice in infection group, inflammatory cells infiltrated and collagenous fibre proliferated around portal areas and egg granulomas. The content of Hyp in liver from mice of NC group, infection group, and experiment group was (279.7 +/- 21.2) microg, (528.0 +/- 15.0) microg, and (355.4 +/- 22.6) microg, respectively. The content of Hyp in livers from mice of experiment group was significantly reduced compared to infection group (P < 0.01). The mRNA expression of alpha-SMA, Col1alpha1 and Ect2 in livers and HSCs from mice in experiment group were significantly down-regulated compared to infection group (P < 0.05).

CONCLUSION

Fasudil hydrochloride can depress hepatofibrosis in Schistosoma japonicum-infected mice.

Schistosomiasis and signet ring cell carcinoma of the rectum

A definitive link between Schistosoma hematobium infection and squamous cell carcinoma of the bladder has been identified. A weaker association between S japonicum infection and colorectal neoplasia has been proposed, although reports are limited to case reports, a case series, and epidemiologic studies. Virtually all cases presented in the literature describe intestinal-type adenocarcinoma occurring in association with S japonicum. We here describe a 40-year-old male Filipino patient with signet ring cell carcinoma of the rectum and evidence of infection by S japonicum.

[Ageing down-modulates the immune responses to Schistosoma japonicum infection in mice]

OBJECTIVE

To investigate the effect of ageing on the immune responses against Schistosoma japonicum infection in mice.

METHODS

Female BALB/c mice were divided into young group (2 months) and old group (18 months), each composed of 8 mice. Each mouse was percutaneously infected with 40 +/- 1 S. japonicum cercariae. At 6 weeks post-infection, the mice were sacrificed, and the spleens were removed and single-cell suspensions of splenocytes were prepared. Worms were perfused from hepatic portal system and counted. The number of eggs in the liver was determined after KOH digestion. Mean single-egg granulomas sizes were determined in stained histological sections. Splenocyte proliferation responses were analyzed by MTT colorimetry. Level of interferon-gamma (IFN-gamma) and interleukin-4 (IL-4) in the splenocyte culture supernatants was determined by ELISA.

RESULTS

The worm burden and egg per gram of liver in old mice [19.75 +/- 1.95, (1.59 +/- 1.05) x 10(4)] were significantly lower than that of young mice [26.00 +/- 2.42, (208 +/- 0.87) x 10(4)] (P < 0.05). The mean volume of single-egg granulomas of the livers in old mice [(30.13 +/- 10.97) x 10(3) mm3] was significantly lower than that of the young mice [(47.02 +/- 24.13) x l0(3) mm3] (P < 0.05).

RESULTS

of T cell proliferation showed that the splenocytes had poorer immune reactivity to ConA in old mice (SI: 1.08 +/- 0.12) than that in young mice (SI: 131 +/- 0.14) (P < 0.05). Levels of IFN-gamma and IL-4 in the splenocyte culture supernatants [(24.05 +/- 6.24), (4.15 +/- 0.68) pg/ml] from old mice were lower than that of young mice [(34.25 +/- 869), (7125 +/- 0.83) pg/ml](P < 0.05).

CONCLUSION

Ageing down-modulates the immune responses and the poorer immune reactivity might decrease pathological alterations in mice infected with Schistosoma japonicum.

Quantifying quality of life and disability of patients with advanced schistosomiasis japonica

BACKGROUND

The Chinese government lists advanced schistosomiasis as a leading healthcare priority due to its serious health and economic impacts, yet it has not been included in the estimates of schistosomiasis burden in the Global Burden of Disease (GBD) study. Therefore, the quality of life and disability weight (DW) for the advanced cases of schistosomiasis japonica have to be taken into account in the re-estimation of burden of disease due to schistosomiasis.

METHODOLOGY/PRINCIPAL FINDINGS

A patient-based quality-of-life evaluation was performed for advanced schistosomiasis japonica. Suspected or officially registered advanced cases in a Schistosoma japonicum-hyperendemic county of the People's Republic of China (P.R. China) were screened using a short questionnaire and physical examination. Disability and morbidity were assessed in confirmed cases, using the European quality of life questionnaire with an additional cognitive dimension (known as the "EQ-5D plus"), ultrasonography, and laboratory testing. The age-specific DW of advanced schistosomiasis japonica was estimated based on patients' self-rated health scores on the visual analogue scale of the questionnaire. The relationships between health status, morbidity and DW were explored using multivariate regression models. Of 506 candidates, 215 cases were confirmed as advanced schistosomiasis japonica and evaluated. Most of the patients reported impairments in at least one health dimension, such as pain or discomfort (90.7%), usual activities (87.9%), and anxiety or depression (80.9%). The overall DW was 0.447, and age-specific DWs ranged from 0.378 among individuals aged 30-44 years to 0.510 among the elderly aged ≥ 60 years. DWs are positively associated with loss of work capacity, psychological abnormality, ascites, and active hepatitis B virus, while splenectomy and high albumin were protective factors for quality of life.

CONCLUSIONS/SIGNIFICANCE

These patient-preference disability estimates could provide updated data for a revision of the GBD, as well as for evidence-based decision-making in P.R. China's national schistosomiasis control program.

[Effects of signal transducers and activators of transcription 4 and 6 on development of worms and granuloma formation in mice infected with Schistosoma japonicum]

OBJECTIVE

To explore the effects of STAT4 and STAT6 on the development of worms and granuloma formation in mice infected with Schistosoma japonicum.

METHODS

All the intact BALB/cJ mice and STAT4(-/-), STAT6(-/-) mice with the same genetic background were infected with 25 S. japonicum cercariae. All the mice were sacrificed on the 42nd day after infection and the worms were collected. The total number of worms and the mean number of worm pairs were counted. The liver of each mouse was removed for the count of eggs, the histological examination and the determination of the size of single-egg granulomas in the liver.

RESULTS

No significant differences were found in the total number of worms, the number of worm pairs and the number of eggs per pair of worms in the liver among STAT4(-/-), STAT6(-/-) and BALB/cJ mice. The size of single-egg granulomas in the liver of STAT6(-/-) mice (213.3 +/- 68.6) microm was significantly smaller than that in the liver of normal BALB/cJ mice (319.5 +/- 71.9) microm (P < 0.05). The liver granulomas were not well formed and the liver fibrosis decreased in STAT6(-/-) mice.

CONCLUSIONS

STAT4 or STAT6 deficiency has no conspicuous effect on the development and fecundity of S. japonicum. STAT6 plays an important role for the granuloma formation and liver fibrosis.

The impact of Schistosoma japonicum infection and treatment on ultrasound-detectable morbidity: a five-year cohort study in Southwest China

BACKGROUND

Ultrasonography allows for non-invasive examination of the liver and spleen and can further our understanding of schistosomiasis morbidity.

METHODOLOGY/PRINCIPAL FINDINGS

We followed 578 people in Southwest China for up to five years. Participants were tested for Schistosoma japonicum infection in stool and seven standard measures of the liver and spleen were obtained using ultrasound to evaluate the relationship between schistosomiasis infection and ultrasound-detectable pathology, and the impact of targeted treatment on morbidity. Parenchymal fibrosis, a network pattern of the liver unique to S. japonicum, was associated with infection at the time of ultrasound (OR 1.40, 95% CI: 1.03-1.90) and infection intensity (test for trend, p = 0.002), adjusting for age, sex and year, and more strongly associated with prior infection status and intensity (adjusted OR 1.84, 95% CI: 1.30-2.60; test for trend: p<0.001 respectively), despite prompt treatment of infections. While declines in parenchymal fibrosis over time were statistically significant, only 28% of individuals with severe parenchymal fibrosis (grades 2 or 3) at enrollment reversed to normal or grade 1 within five years. Other liver abnormalities were less consistently associated with S. japonicum infection.

CONCLUSIONS/SIGNIFICANCE

Parenchymal fibrosis is an appropriate measure of S. japonicum morbidity and can document reductions in disease following control efforts. Other ultrasound measures may have limited epidemiological value in regions with similar infection levels. Because severe fibrosis may not reverse quickly following treatment, efforts to reduce exposure to S. japonicum should be considered in combination with treatment to prevent schistosomiasis morbidity.

Co-ordinated gene expression in the liver and spleen during Schistosoma japonicum infection regulates cell migration

Determining the molecular events induced in the spleen during schistosome infection is an essential step in better understanding the immunopathogenesis of schistosomiasis and the mechanisms by which schistosomes modulate the host immune response. The present study defines the transcriptional and cellular events occurring in the murine spleen during the progression of Schistosoma japonicum infection. Additionally, we compared and contrasted these results with those we have previously reported for the liver. Microarray analysis combined with flow cytometry and histochemistry demonstrated that transcriptional changes occurring in the spleen were closely related to changes in cellular composition. Additionally, the presence of alternatively activated macrophages, as indicated by up-regulation of Chi3l3 and Chi3l4 and expansion of F4/80⁺ macrophages, together with enhanced expression of the immunoregulatory genes ANXA1 and CAMP suggests the spleen may be an important site for the control of S. japonicum-induced immune responses. The most striking difference between the transcriptional profiles of the infected liver and spleen was the contrasting expression of chemokines and cell adhesion molecules. Lymphocyte chemokines, including the homeostatic chemokines CXCL13, CCL19 and CCL21, were significantly down-regulated in the spleen but up-regulated in the liver. Eosinophil (CCL11, CCL24), neutrophil (CXCL1) and monocyte (CXCL14, CCL12) chemokines and the cell adhesion molecules VCAM1, NCAM1, PECAM1 were up-regulated in the liver but unchanged in the spleen. Chemokines up-regulated in both organs were expressed at significantly higher levels in the liver. Co-ordinated expression of these genes probably contributes to the development of a chemotactic signalling gradient that promotes recruitment of effector cells to the liver, thereby facilitating the development of hepatic granulomas and fibrosis. Together these data provide, for the first time, a comprehensive overview of the molecular events occurring in the spleen during schistosomiasis and will substantially further our understanding of the local and systemic mechanisms driving the immunopathogenesis of this disease.

Schistosomiasis is a significant cause of illness and death in the developing world. Inflammation and scarring in the liver and enlargement of the spleen (splenomegaly) are common features of the disease. Changes occurring in the spleen have the potential to influence the way in which the body deals with infection but the mechanisms driving these changes are not well characterised. In the present study we determined, for the first time, the gene expression profile of the mouse spleen during infection with Schistosoma japonicum and compared these results to those previously reported for the liver to determine if processes occurring in these organs co-operate to promote hepatic inflammation and granuloma formation. Our data indicated that gene expression in the spleen is related to the types of cells present and suggest that the spleen might be important in controlling schistosome-induced inflammation. Comparison of the liver and spleen showed that expression of cell signalling molecules (chemokines) was much higher in the liver, potentially promoting the recruitment of specific cell types to this organ, causing inflammation and scarring. The results from this study enhance our knowledge of the mechanisms that drive schistosome-induced splenomegaly and liver inflammation.

[Effect of paeoniflorin on hepatic immunopathogenesis in mice with Schistosoma japonicum infection]

OBJECTIVE

To investigate the mechanism of paeoniflorin in preventing hepatic granuloma formation and fibrosis in mice infected with Schistosoma japonicum.

METHODS

Model of hepatic granuloma and fibrosis was established by infecting mice with S. japonicum cercariae. The infected mice were randomly divided into 4 groups: group A as model (infected control) group (15 mice), and paeoniflorin being given before, simultaneously and after praziquantel treatment as groups B, C and D. Each of the groups B, C and D was subdivided into 3 subgroups (15 mice each): low dose (paeoniflorin 2 ml, 30 mg/(kg x d) x 30 d), high dose(paeoniflorin 2 ml, 120 mg/(kg x d) x 30 d) and control (2 ml, 0.5% sodium carboxymethylcellulose x 30 d). In group B, paeoniflorin or sodium carboxymethylcellulose was orally administrated on 12 d after infection. In groups C and D, paeoniflorin or sodium carboxymethylcellulose was administrated on 42 d or 72 d after infection. Each of group B, C and D was orally given praziquantel 2 ml (500 mg/(kg x d) x 2 d) on 42 d after infection. On the 102nd day after infection, all animals were sacrificed by cervical dislocation. Serum hyaluronic acid (HA) was detected by radioimmunoassay; area of egg granuloma and degree of hepatic fibrosis were observed via HE and Masson stainings; the expression of transforming growth factor beta1 (TGF-beta1), alpha smooth muscle actin (alpha-SMA and collagen I (Col I) protein were measured by immunohistochemical method.

RESULTS

In group B, the level of HA (0.719 +/- 0.239 microg/ml, 0.721 +/- 0.182 microg/ml) in low or high dose subgroups was significantly lower (F = 9.429, P < 0.01) than the control subgroup (1.049 +/- 0.286 microg/ml); the area of granuloma (0.066 +/- 0.005 mm2, 0.064 +/- 0.004 mm2) or the degree of hepatic fibrosis (2.067 +/- 0.458, 1.967 +/- 0.399) in low or high dose subgroups was significantly greater (F = 862.540, F = 29.738, P < 0.01) than the control (0.141 +/- 0.008 mm2, 3.467 +/- 0.834); the expression of alpha-SMA positive cells (2.933 +/- 0.594, 3.000 +/- 0.535) in low or high dose subgroups was significantly lower (F = 12.323, P < 0.01, P < 0.01) than its control (4.800 +/- 1.859); the expression of TGF-beta1 (0.256 +/- 0.057, 0.274 +/- 0.054) in low or high dose subgroups was significantly lower (F = 148.990, P < 0.01) than its control (0.552 +/- 0.047); the content of Col I (0.334 +/- 0.041, 0.339 +/- 0.042) in low or high dose subgroups was significantly lower (F = 180.881, P < 0.01) than its control (0.601 +/- 0.049). In groups C & D, no significant difference was found between the low or high dose subgroups or between the subgroups and their corresponding controls.

CONCLUSION

Paeoniflorin can significantly reduce hepatic granuloma formation and fibrosis due to schistosome eggs, and decrease the expression of TGF-beta1, alpha-SMA in mice when it is given before praziquantel administration, which may associate with the activation of hepatic stellate cells and the expression of TGF-beta1 in liver tissue.

Surgical treatment of epilepsy with chronic cerebral granuloma caused by Schistosoma japonicum

PURPOSE

To study the surgical treatment of epilepsy with cerebral granuloma caused by Schistosoma japonicum.

METHODS

Two hundred fifty cases of epilepsy caused by cerebral schistosomiasis from 1955 to 2004 were analyzed retrospectively.

RESULTS

There were no deaths. Follow-up of 196 cases for 4-5 years after operation demonstrated that 180 cases (92%) were seizure-free or well-controlled.

CONCLUSIONS

Surgical treatment should be considered when drug therapy fails to control epilepsy or the lesion shows mass effect. Intraoperative electrocorticography monitoring is helpful to define the extent of the resection of the lesion.

Radiology corner. Answer to last month's radiology case and images: Schistosomiasis japonicum involving the liver and colon

Abdominal radiography showed subtle curvilinear densities overlying the left lower quadrant and central within the pelvis (Fig. 1a). This was confirmed on intravenous contrast-enhanced abdominopelvic CT to be caused by thin mucosal surface calcifications within the descending and sigmoid colons (Fig. 1b, c). Incidental note is made of thin right hepatic lobe capsule calcifications (Fig. 1d). These colonic and hepatic calcifications are characteristic of Schistosomiasis infection of the gastrointestinal tract. Liver biopsy confirmed Schistosomiasis japonicum infection.