Infectivity and pathological changes in murine clonorchiasis: comparison in immunocompetent and immunodeficient mice

Host genetic backgrounds: the key to determining parasite-host adaptation

Parasitic diseases pose a significant threat to global public health, particularly in developing countries. Host genetic factors play a crucial role in determining susceptibility and resistance to infection. Recent advances in molecular and biological technologies have enabled significant breakthroughs in understanding the impact of host genes on parasite adaptation. In this comprehensive review, we analyze the host genetic factors that influence parasite adaptation, including hormones, nitric oxide, immune cells, cytokine gene polymorphisms, parasite-specific receptors, and metabolites. We also establish an interactive network to better illustrate the complex relationship between host genetic factors and parasite-host adaptation. Additionally, we discuss future directions and collaborative research priorities in the parasite-host adaptation field, including investigating the impact of host genes on the microbiome, developing more sophisticated models, identifying and characterizing parasite-specific receptors, utilizing patient-derived sera as diagnostic and therapeutic tools, and developing novel treatments and management strategies targeting specific host genetic factors. This review highlights the need for a comprehensive and systematic approach to investigating the underlying mechanisms of parasite-host adaptation, which requires interdisciplinary collaborations among biologists, geneticists, immunologists, and clinicians. By deepening our understanding of the complex interactions between host genetics and parasite adaptation, we can develop more effective and targeted interventions to prevent and treat parasitic diseases. Overall, this review provides a valuable resource for researchers and clinicians working in the parasitology field and offers insights into the future directions of this critical research area.

Anti‐shigellosis activity of the aqueous extract of garlic, clove and fenugreek

Shigellosis causes severe diarrhea and, in some cases, death in children. In this study, we investigated the in vitro and in vivo anti‐shigellosis efficacy of some aqueous herbal extracts or their chosen mixtures, including fenugreek seed, black seed, clove, garlic, and ginger. The antibacterial potential was assessed by well diffusion and microdilution assays. The extracts' minimum inhibitory concentrations ranged from 0.39 to 12.5 mg/ml. The water extract of garlic and combinations of garlic with either fenugreek or clove extracts had the highest antibacterial efficacy, hence these extracts were chosen for the in vivo investigation. Rats were given a Shigella dysenteriae inoculum and then administrated two doses (100 and 200 mg/kg bw) of the selected herbal extracts or the antibiotic ciprofloxacin (20 mg/kg bw) to treat Shigellosis in vivo. The results showed that garlic and clove extract mixtures (G6, 200 mg/kg bw), garlic and fenugreek mixtures (G7 and G8, 100 and 200 mg/kg bw), and ciprofloxacin group (G9, 20 mg/kg bw) had the best anti‐Shigellosis efficacy. G7 (garlic and fenugreek mixtures (100 mg/kg bw) outperformed almost all other groups evaluated. This group had lower defecation frequency, lower stool‐Shigella loudness, restored body weight, recovered hematological, and liver and kidney functions, besides exhibited no anatomical alterations in the colon tissue that were comparable to the uninfected group. As a result, in the treatment of Shigella, this extract combination may be suggested as a viable therapeutic alternative to antibiotics.

Molecular Mechanisms of Clonorchis sinensis-Host Interactions and Implications for Vaccine Development

Infections caused by Clonorchis sinensis remain a significant public health challenge for both humans and animals, causing pyogenic cholangitis, cholelithiasis, cholecystitis, biliary fibrosis, and even cholangiocarcinoma. However, the strategies used by the parasite and the immunological mechanisms used by the host have not yet been fully understood. With the advances in technologies and the accumulated knowledge of host-parasite interactions, many vaccine candidates against liver flukes have been investigated using different strategies. In this review, we explore and analyze in-depth the immunological mechanisms involved in the pathogenicity of C. sinensis. We highlight the different mechanisms by which the parasite interacts with its host to induce immune responses. All together, these data will allow us to have a better understanding of molecular mechansism of host-parasite interactions, which may shed lights on the development of an effective vaccine against C. sinensis.

The dynamics of select cellular responses and cytokine expression profiles in mice infected with juvenile Clonorchis sinensis

Clonorchiasis is a zoonotic disease that can result in chronic infection in humans. The causative agent, Clonorchis sinensis (C. sinensis), is believed to primarily induce a Th2 immune response in infected mice. However, few studies have profiled host immune responses to C. sinensis infection during the juvenile phase. In the present study, the dynamics of select cellular responses and cytokine expression profiles during juvenile C. sinensis infection were investigated. The flow cytometry results showed that the CD4+ T cells percentage was significantly decreased between 12 days post-infection (dpi) and 24 dpi in the peripheral blood, and the CD8+ T cells percentage was significantly elevated after 3 dpi. The ratio of CD4+/CD8+ T cells was also significantly decreased after 3 dpi. Furthermore, we observed that the proportion of CD14+ monocyte-macrophages in the peripheral blood was significantly increased between 1 dpi and 12 dpi and peaked at 6 dpi. The percentage of classically activated macrophages (M1) and alternatively activated macrophages (M2) in the liver was significantly increased between 18 dpi and 30 dpi. qRT-PCR results showed that the expression levels of iNOS in the liver were significantly elevated after 3 dpi, and Arg-1 expression was significantly increased beginning at 12 dpi. ELISA results showed that the serum levels of the Th1 cytokines IFN-γ and IL-2 peaked at 6 dpi and decreased thereafter. Furthermore, the Th2 cytokines IL-4 and IL-13 began to be expressed and peaked at 24 dpi and 30 dpi, respectively. In addition, the levels of the Treg cytokines IL-10 and TGF-β₁ were significantly increased beginning at 6 dpi until 30 dpi. In the liver homogenate, the expression of IFN-γ, IL-2, and IL-4 mainly occurred before 6 dpi. IL-13 expression was significantly increased at 30 dpi. IL-10 and TGF-β₁ levels were significantly increased at 12 dpi and 24 dpi, and expression peaked at 24 dpi and 30 dpi, respectively. This study provides a fundamental characterization for the future analysis of host-parasite interactions and immune responses in hosts infected with juvenile C. sinensis.

Demographics and Clinical Presentation of Early-Stage Legg-Calvé-Perthes Disease: A Prospective, Multicenter, International Study

BACKGROUND

Children with Legg-Calvé-Perthes disease (LCPD) are classically described as small, thin, high-energy children presenting with a painless limp. Epidemiologic studies have historically been retrospective and regional in nature. The purpose of this study was to determine the demographic and clinical features of children presenting in the early stages of LCPD in an international, multicenter cohort.

METHODS

Children (6 to 10 years) in the early stages of LCPD (modified Waldenström stage I to IIa) were enrolled in a prospective, multicenter study. Demographic and clinical data at presentation were analyzed. Body mass index percentiles were determined using country-specific growth charts for children in the United States and India, two countries with largest enrollment. Statistical analyses included t-tests and chi-square.

RESULTS

A total of 209 children (86% males; mean age 7.9 ± 1.2 years) from 25 centers (six countries) were included. Eight-four percent of children presented with pain with or without a limp. Average pain score at presentation was 3 ± 2 (range 0 to 9), and 63% of children (n = 105) used pain medications. Of these children 65% required medication more than once per week. Thirty percent of children missed school due to pain in the past month, and of those, 74% missed at least 1 day per week. Twenty-nine percent of children from the United States and 20% of children from India were overweight or obese. Nineteen percent reported household smoking.

DISCUSSION

This prospective study provides a new international multicenter representation of early LCPD. The frequency of pain and missed school highlights the substantial morbidity and potential social cost and burden for children and families. The prevalence of being overweight/obese in our LCPD cohort was comparable to rates within the pediatric cohort as a whole, and fewer children have a history of smoke exposure than in previous reports.

LEVEL OF EVIDENCE

Level II, prospective comparative study.

TLR4 Deficiency Exacerbates Biliary Injuries and Peribiliary Fibrosis Caused by Clonorchis sinensis in a Resistant Mouse Strain

Mice with different genetic backgrounds have various susceptibilities to infection with Clonorchis sinensis, although the mechanisms underlying are largely unknown. Toll-like receptor 4 (TLR4) as one of the most important pattern recognition receptors (PPRs) is essential for the invasion, survival, pathogenesis, and elimination of worms. The roles played by TLR4 in C. sinensis infection may vary due to the different genetic backgrounds of mice. In the present study, a relatively resistant mouse strain-C57BL/10 to C. sinensis was used for investigation on the possible roles of TLR4 in the biliary injuries and peribiliary fibrosis. TLR4 wild type (TLR4^wild) and TLR4 defective (TLR4^def) mice were orally infected with 45 metacercariae of C. sinensis, and all C. sinensis-infected mice and non-infected groups were anesthetized on day 28 post-infection. The liver and serum from each mouse were collected for assessment of the biliary injuries and biliary fibrosis. Meanwhile, hepatic leukocytes were isolated and detected for the activation of M1 or M2 macrophage using flow cytometry. The hepatic type 1 immune response and type 2 immune responses -relative molecules were also evaluated using ELISA and quantitative PCR. The data showed that TLR4^def aggravated liver inflammatory cell infiltrations, bile duct proliferation, biliary and hepatocellular injuries, and ECM deposition in C. sinensis-infected mice, compared with TLR4^wild mice when they were intragastrically administered with the same amounts of C. sinensis metacercaria. Furthermore, the M2-like macrophages and type 2 immune responses were significantly predominant induced in TLR4^def mice, compared with that of TLR4^wild mice following C. sinensis infection. But the type 1 immune response were significantly decreased in TLR4^def mice, compared with TLR4^wild mice after C. sinensis infection. These data demonstrate that TLR4 deficiency exacerbates biliary injuries and peribiliary fibrosis caused by C. sinensis in C57BL/10 strain mice, which is contributed by augments of type 2 immune responses and decrease pro-inflammatory responses.

Protective effect of rosemary (Rosmarinus officinalis) against diethylnitrosamine-induced renal injury in rats

Context: The kidney plays a central role in detoxification and excretion of toxic metabolites, and therefore, is susceptible to toxicity by xenobiotics.Objective: To investigate the protective effect of Rosmarinus officinalis (rosemary) powder and its essential (volatile) oil against diethylnitrosamine (DEN)-induced renal injury in rats.Materials and methods: Phenolic and flavonoid components were characterised in rosemary powder using HPLC-UV instrument while rosemary essential oil (E.O) was investigated via GC-MS technique. In rat model, rosemary was administrated orally (in diet) for two months. Lipid profile, antioxidant biomarkers, kidney functions and histopathological examinations were assessed.Results: Hesperidin (4878.88 ppm) and ellagic acid (403.57 ppm) are among the major phenolic and flavonoid constituents in rosemary powder. Camphor (18.36%) and α-pinene (12.74%) represent the main E.O active ingredients. Rats treated with rosemary E.O showed a significant elevation in serum HDL (28.28%) accompanied by a decrease in LDL (115.47%). A significant decrease in serum creatinine and urea was also reported (69.72 and 109.89%, respectively). Moreover, serum glutathione peroxidise (GSH-Px) activity has been significantly increased. Kidney histopathological examinations confirmed the protective effect against DEN-induced abnormalities.Conclusion: Rosemary (powder/E.O) was able to reduce or even prevent the severity of diethylnitrosamine-induced renal dysfunction.

Phytochemicals, antioxidant activity and hepatoprotective effect of ginger (Zingiber officinale) on diethylnitrosamine toxicity in rats

Context: Chronic liver damage has serious medical consequences. Objective: To investigate the hepatoprotective effect of dry Zingiber officinale (ginger) and its essential (volatile) oil against diethylnitrosamine (DEN) toxicity in rats. Materials and methods: Phenols and flavonoids components were characterized in dry ginger using HPLC-UV instrument while ginger essential oil (E.O.) was investigated via GC-MS technique. Antioxidant activity was determined in vitro. In rat model, ginger was administrated for 2 months. Lipid profile, antioxidant biomarkers, liver functions and histopathology were assessed. Results: Chlorogenic acid (63.85 ppm) and hesperidin (156.91 ppm) are among the major phenolic and flavonoid constituents in dry ginger. Curcumene (15.21%) and linalool (13.47%) represent the main E.O. constituents. In rats treated with ginger E.O., a significant elevation in serum HDL (31.14%) was accompanied by a decrease in LDL (55.14%). A significant decrease in serum ALT and ALP was reported (56.85% and 53.84%, respectively). Serum GSH-Px activity has significantly increased 75.06%. Meanwhile, E.O. showed anticancer potential against HepG2 cell line (IC50 = 40 µg/mL). Liver histopathological examinations confirmed the protective effect against abnormalities. Conclusion: Ginger was able to reduce the severity of DEN-cytotoxicity in rats, which suggests a novel antioxidant role originating from this medicinal plant.

Membrane-bound IgE on B cells is increased during Clonorchis sinensis infection

A high level of serum IgE is a hallmark of helminthic disease. Secretory IgE can bind FcεRI or FcεRII/CD23. The combination of IgE and FcεRI, a high-affinity interaction, has long received attention and is believed to facilitate helminth control, while the properties of CD23-bound IgE have long been unexplored. Here, we established a Clonorchis sinensis (C. sinensis) infection model with different mouse strains and investigated membrane-bound IgE on B cells during infection. We show that after infection, the increase in CD23 expression on B cells was obvious, even in relatively resistant C57BL/6 mice, as well as in susceptible BALB/c and FVB mice. Although the serum IgE amount was lower in C57BL/6 mice than in BALB/c and FVB mice, the level of IgE binding to peripheral B cells was also elevated. Additionally, the IgE on B cells was soon undetectable in vitro due to dissociable binding. The results of the present study demonstrate the dramatic increase in CD23-bound IgE on B cells after C. sinensis infection. The significance of CD23-bound IgE in Ag transport and presentation has gained consideration in allergy development for its potential ability to promote the Th2 response. Therefore, even though the association of IgE and CD23 is not as substantial as that of IgE and FcεRI, membrane-bound IgE on B cells may be worth further study regarding clonorchiasis and other parasitic infections.

Investigation on oxidative stress of nitric oxide synthase interacting protein from Clonorchis sinensis

Numerous evidences indicate that excretory-secretory products (ESPs) from liver flukes trigger the generation of free radicals that are associated with the initial pathophysiological responses in host cells. In this study, we first constructed a Clonorchis sinensis (C. sinensis, Cs)-infected BALB/c mouse model and examined relative results respectively at 3, 5, 7, and 9 weeks postinfection (p.i.). Quantitative reverse transcription (RT)-PCR indicated that the transcriptional level of both endothelial nitric oxide synthase (eNOS) and superoxide dismutase (SOD) gradually decreased with lastingness of infection, while the transcriptional level of inducible NOS (iNOS) significantly increased. The level of malondialdehyde (MDA) in sera of infected mouse significantly increased versus the healthy control group. These results showed that the liver of C. sinensis-infected mouse was in a state with elevated levels of oxidation stress. Previously, C. sinensis NOS interacting protein coding gene (named CsNOSIP) has been isolated and recombinant CsNOSIP (rCsNOSIP) has been expressed in Escherichia coli, which has been confirmed to be a component present in CsESPs and confirmed to play important roles in immune regulation of the host. In the present paper, we investigated the effects of rCsNOSIP on the lipopolysaccharide (LPS)-induced activated RAW264.7, a murine macrophage cell line. We found that endotoxin-free rCsNOSIP significantly promoted the levels of nitric oxide (NO) and reactive oxygen species (ROS) after pretreated with rCsNOSIP, while the level of SOD decreased. Furthermore, rCsNOSIP could also increase the level of lipid peroxidation MDA. Taken together, these results suggested that CsNOSIP was a key molecule which was involved in the production of nitric oxide (NO) and its reactive intermediates, and played an important role in oxidative stress during C. sinensis infection.

The expression dynamics of transforming growth factor-β/Smad signaling in the liver fibrosis experimentally caused by Clonorchis sinensis

Background

Liver fibrosis is a hallmark of clonorchiasis suffered by millions people in Eastern Asian countries. Recent studies showed that the activation of TGF-β/Smad signaling pathway can potently regulate the hepatic fibrogenesis including Schistosoma spp. and Echinococcus multilocularis-caused liver fibrosis. However, little is known to date about the expression of transforming growth factor-β (TGF-β) and other molecules in TGF-β/Smad signaling pathway which may play an important role in hepatic fibrosis caused by C. sinensis.

Methods

A total of 24 mice were individually infected orally with 45 metacercariae, both experimental mice and mocked-infected control mice were anesthetized at 4 week post-infection (wk p.i.), 8 wk p.i. and 16 wk p.i., respectively. For each time-point, the liver and serum from each animal were collected to analyze histological findings and various fibrotic parameters including TGF-β₁, TGF-β receptors and down-stream Smads activation, as well as fibrosis markers expression.

Results

The results showed that collagen deposition indicated by hydroxyproline content and Masson’s trichrome staining was increased gradually with the development of infection. The expression of collagen type α1 (Col1a) mRNA transcripts was steadily increased during the whole infection. The mRNA levels of Smad2, Smad3 as well as the protein of Smad3 in the liver of C. sinensis-infected mice were increased after 4 wk p.i. (P < 0.05, compared with normal control) whereas the TGF-β₁, TGF-β type I receptor (TGFβRI) and TGF-β type II receptor (TGFβRII) mRNA expression in C. sinensis-infected mice were higher than those of normal control mice after 8 wk p.i. (P < 0.05). However, the gene expression of Smad4 and Smad7 were peaked at 4 wk p.i. (P < 0.05), and thereafter dropped to the basal level at 8 wk p.i., and 16 wk p.i., respectively. The concentrations of TGF-β₁ in serum in the C. sinensis-infected mice at 8 wk p.i. and 16 wk p.i (P < 0.05) were significantly higher than those in the control mice.

Conclusions

The results of the present study indicated for the first time that the activation of TGF-β/Smad signaling pathway might contribute to the synthesis of collagen type I which leads to liver fibrosis caused by C. sinensis.

Clonorchis sinensis ferritin heavy chain triggers free radicals and mediates inflammation signaling in human hepatic stellate cells

Clonorchiasis, caused by direct and continuous contact with Clonorchis sinensis, is associated with hepatobiliary damage, inflammation, periductal fibrosis, and the development of cholangiocarcinoma. Hepatic stellate cells respond to liver injury through production of proinflammatory mediators which drive fibrogenesis; however, their endogenous sources and pathophysiological roles in host cells were not determined. C. sinensis ferritin heavy chain (CsFHC) was previously confirmed as a component of excretory/secretory products and exhibited a number of extrahepatic immunomodulatory properties in various diseases. In this study, we investigated the expression pattern and biological role of CsFHC in C. sinensis. CsFHC was expressed throughout life stages of C. sinensis. More importantly, we found that treatment of human hepatic stellate cell line LX-2 with CsFHC triggered the production of free radicals via time-dependent activation of NADPH oxidase, xanthine oxidase, and inducible nitric oxide synthase. The increase in free radicals substantially promoted the degradation of cytosolic IκBα and nuclear translocation of NF-κB subunits (p65 and p50). CsFHC-induced NF-κB activation was markedly attenuated by preincubation with specific inhibitors of corresponding free radical-producing enzyme or the antioxidant. In addition, CsFHC induced an increased expression level of proinflammatory cytokines, IL-1β and IL-6, in NF-κB-dependent manner. Our results indicate that CsFHC-triggered free radical-mediated NF-κB signaling is an important factor in the chronic inflammation caused by C. sinensis infection.

Free radicals enzymatically triggered by Clonorchis sinensis excretory-secretory products cause NF-κB-mediated inflammation in human cholangiocarcinoma cells

Chronic clonorchiasis, caused by direct and continuous contact with Clonorchis sinensis worms and their excretory-secretory products, is associated with hepatobiliary damage, inflammation, periductal fibrosis and even development of cholangiocarcinoma. Our previous report revealed that intracellular reactive oxygen species were generated in C. sinensis excretory-secretory product-treated human cholangiocarcinoma cells; however, their endogenous sources and pathophysiological roles in host cells were not determined. In the present study, we found that treatment of human cholangiocarcinoma cells with excretory-secretory products triggered increases in free radicals via a time-dependent activation of NADPH oxidase, xanthine oxidase and inducible nitric oxide synthase. This increase in free radicals substantially promoted the degradation of cytosolic IκB-α, nuclear translocation of nuclear factor-κB subunits (RelA and p50), and increased κB consensus DNA-binding activity. Excretory-secretory product-induced nuclear factor-κB activation was markedly attenuated by preincubation with specific inhibitors of each free radical-producing enzyme or the antioxidant, N-acetylcysteine. Moreover, excretory-secretory products induced an increase in the mRNA and protein expression of the proinflammatory cytokines, IL-1β and IL-6, in an nuclear factor-κB-dependent manner, indicating that enzymatic production of free radicals in ESP-treated cells participates in nuclear factor-κB-mediated inflammation. These findings provide new insights into the pathophysiological role of C. sinensis excretory-secretory products in host chronic inflammatory processes, which are initial events in hepatobiliary diseases.

Cyst formation, increased anti-inflammatory cytokines and expression of chemokines support for Clonorchis sinensis infection in FVB mice

To verify the hypothesis that different pathology of Clonorchis sinensis infection by mouse strains is determined by different responses of cytokines and chemokines, we compared those responses of FVB with those of BALB/c mice. All of FVB mice infected with 30 metacercariae of C. sinensis showed cystic dilatation in the liver, whereas infected BALB/c mice did not. Mature worms were recovered from 19 of 20 liver sections of FVB mice while only one of 20 sections of BALB/c mice revealed a mature worm. In both strains the proportion of CD4(+) T cells was lower in C. sinensis-infected than in the uninfected group. However, the proportion of CD8(+) T cells was elevated in C. sinensis-infected from both strains compared to uninfected mice. The Th2-associated anti-inflammatory cytokines such as IL-4, IL-5 and IL-13, IL-10 and TGF-β, were significantly more produced by the lymphocytes of FVB than by those of BALB/c mice. Especially, the 2 anti-inflammatory cytokines, IL-10 and TGF-β, were presumably related with susceptibility and the development of worms in the liver. C. sinensis infected FVB mice also produced more chemokines such as RANTES and MIP-1α in the liver lymphocytes than BALB/c mice. In conclusion, the FVB mice provide the favorable niche for C. sinensis by cyst formation in the bile duct, increased production of Th2-associated anti-inflammatory cytokines and upregulation of chemokines.

Strain variation in the susceptibility and immune response to Clonorchis sinensis infection in mice

Mice have shown various susceptibility to infection by Clonorchis sinensis. To compare the intra-specific variation in the host-parasite relationship of C. sinensis, 6 strains of mice (ICR, BALB/c, C57BL/6, DDY, CBA/N, and C3H/HeN) with 3 different haplotypes were evaluated on their susceptibility. The worm recovery rate and immunological responses were observed after 4 and 8 weeks of infection with 30 metacercariae. The highest worm recovery rate was observed as 20.7% in the C3H/HeN strain after 4 weeks of infection along with histopathological changes. The rate was 10.0% in C57BL/6 mice after 8 weeks. ICR, BALB/c, and CBA/N showed elevated levels of IgE at both time points when compared to the rest of the strains. The serum IgG1 and IgG2a levels were elevated in most of the strains; however, the C57BL/6 strain showed a lower level of IgG2a that indicated the IgG1 predominance over IgG2a. The production of IL-4 after concanavalin-A stimulation of splenocytes slightly increased among the mouse strains except C3H/HeN after 4 or 8 weeks of infection, but each strain produced high levels of IFN-γ after 8 weeks, which implied mixed Th1/Th2 responses. ICR, DDY, CBA/N, and C3H/HeN strains showed a significantly increased level of IL-10 after 8 weeks as compared to C57BL/6. All of the strains showed an increased level of IL-13 and suggested fibrotic changes in the mice. In conclusion, mice are insusceptible to infection with C. sinensis; however, the C57BL/6, BALB/c and ICR strains are relatively susceptible after 8 weeks of infection among the six strains. Worm expulsion may be one of the causes of low susceptibility of C3H/HeN mice strain at the 8th week. Elevated IgE, IFN-γ, and IL-13 of infected mice suggest both Th1 and Th2 responses that may be related to the low host susceptibility.

FVB/N mice are highly resistant to primary infection with Nippostrongylus brasiliensis

Nippostrongylus brasiliensis larvae are particularly susceptible to immunological attack during the pre-lung stage of primary and secondary infections in mice. Whilst most of the common laboratory strains of mice are permissive hosts for the parasite, in this study we report for the first time, the strong resistance of naive FVB/N mice to N. brasiliensis. Damage to larvae is evident within the first 24 h of infection and this may be critical to later larval development and reproductive success. Inflammatory responses in the skin, and larval escape from this tissue were comparable in susceptible CBA/Ca and resistant FVB/N mice, with most larvae exiting within 4 h of a primary infection. Lung larval burdens were also similar between strains, but larvae recovered from FVB/N mice were smaller and less motile. In FVB/N mice, larval colonization of the gut was impaired and worms produced very few eggs. However FVB/N mice did not show enhanced resistance to Heligmosomoides bakeri (also known as Heligmosomoides polygyrus), a nematode largely restricted to the gut. Damage done in the pre-lung or lung stages of infection with N. brasiliensis is likely to contribute to ongoing developmental and functional abnormalities, which are profoundly evident in the gut phase of infection.

Development of resistance to reinfection by Clonorchis sinensis in rats

We investigated the induction of resistance to Clonorchis sinensis infection by prior infection in rat and hamster models. Animals were challenged with C. sinensis metacercariae, then treated with praziquantel and reinfected. Worm recovery rate in reinfected animals was used to estimate resistance to reinfection. The determined resistance rates to reinfection in rats and hamsters were 97.7% and 10.3%, respectively. In rats, cure from the primary infection of C. sinensis increased resistant to reinfection, and the greater the worm burden and the longer the duration of primary infection, the higher was the resistance rate. For primary infection doses of 10, 40 and 100 metacercariae per rat, the resistance rates were 87.4%, 93.8% and 98.4%, respectively. The resistance rates in rats after 2 or 8-week primary infection were 78.7% and 95.3%, respectively. All worms recovered from reinfected rats were immature. When cured rats were administered with methylprednisolone, resistance to reinfection became impaired. These findings indicate that rats develop a high degree of resistance to reinfection by C. sinensis after cure. The growths and maturations of reinfected worms were also impaired.

Clinical and epidemiological data of patients with clonorchiasis

AIM: To study the clinical and epidemiological features of patients with clonorchiasis so as to provide scientific evidences for the diagnosis and prevention of clonorchiasis.

METHODS: Stools from 282 subjects suspected of having clonorchiasis were examined for helminth eggs with modified Kato’s thick smear and sedimentation methods, and their sera were tested for HAV-DNA, HBV-DNA, HCV-RNA, HDV-RNA and HEV-RNA with polymerase chain reaction (PCR). Clinical symptoms of patients with clonorchiasis only were analyzed, and their blood samples were tested for circulating antigen (CAg) with Dot-ELISA, esoinophilic granulocyte count, and alanine aminotransferase (ALT). Meanwhile, they were asked to provide data of occupation, eating habit, hygienic habit and knowledge of clonorchiasis. In addition, the ecosystem of the environment in epidemic areas was surveyed.

RESULTS: Among the 282 patients, 61 (21.43%) were infected with clonorchis sinensis only, 97 (34.64%) were co-infected with clonorchis sinensis and other pathogens, 92 (32.86%) were infected with hepatitis virus only and 31 (11.07%) neither with clonorchis sinensis nor hepatitis virus. Among the 61 patients with clonorchiasis only, there were 14 (22.95%) subjects with discomfort over hepatic region or epigasfrium, 12 (19.67%) with general malaise or discomfort and inertia in total body, 6 (9.84%) with anorexia, indigestion and nausea, 4 (6.56%) with fever, dizziness and headache (6.56%), and 25 (40.98%) without any symptoms; sixty one (100%) with CAg (+), 98.33% (59/60) with eosinophilic granulocytes increased and 65.00% (39/60) with ALT increased. B-mode ultrasonography revealed 61 cases with dilated and thickened walls of intrahepatic bile duct, and blurred patchy echo acoustic image in liver. Twenty-six cases had stones in the bile duct, 39 cases had slightly enlarged liver with diffuse coarse spots in liver parenchyma. Twenty cases had enlarged gallbladder with thickened coarse wall and image of floating plagues, 9 cases had slightly enlarged spleen. By analysis of epidemiological data, we found that the ecologic environment was favorable for the epidemiology of clonorchiasis. Most patients with clonorchiasis were lack of knowledge about the disease. Their living environment, hygienic habits, eating habits and their occupations were the related factors that caused the prevalence of the disease.

CONCLUSION: The clinical symptoms of clonorchiasis are non-specific, and the main evidences for diagnosis of clonorchiasis should be provided by etiologic examination, B-mode ultrasonography and clinical history. The infection of clonorchis sinensis is related to occupations, bad eating habits and lack of knowledge about prevention of the disease.

Cytokine responses in mice infected with Clonorchis sinensis

FVB and BALB/c mice show different morbidity, development of Clonorchis sinensis, and pathological changes following C. sinensis infection. FVB mice are susceptible and BALB/c mice are relatively more resistant to C. sinensis infection. To investigate the relationship between cytokine reaction and susceptibility to C. sinensis infection in FVB and BALB/c mice, we described both the patterns and kinetics of Th1 cytokines and Th2 cytokines in spleen cell culture. Interleukin (IL)-4 and IL-10 cytokine production in the culture supernatants of the concanavalin-A-stimulated spleen cells increased at 2-3 weeks post-infection in both strains. IL-5 production increased between 2 and 5 weeks post-infection in both strains, and reached a peak level at 2 weeks post-infection in BALB/c mice and 4 weeks post-infection in FVB mice. In contrast, gamma interferon (IFN-gamma) production decreased between 2 and 4 weeks in both strains. IL-2 production increased slightly in BALB/c mice following infection, but was unchanged in FVB mice. IL-4 production over preinfection levels was significantly higher in FVB mice, whereas IFN-gamma, IL-2, and IL-10 production were significantly higher in BALB/c mice. The levels of serum immunoglobulin E (IgE) and blood eosinophils in both mouse strains significantly increased between 3 and 6 weeks postinfection. Serum IgE levels were significantly higher in FVB mice than in BALB/c mice. The results of this study suggest that susceptibility to C. sinensis infection is associated with Th2 cytokine production, especially IL-4 which is predominant in relatively susceptible FVB mice.