Transplantation of adipose-derived stem cells ameliorates Echinococcus multilocularis-induced liver fibrosis in mice.

BACKGROUND: Alveolar echinococcosis (AE) can cause severe liver fibrosis and could be fatal if left untreated. Currently, there are no effective therapeutic options for AE-induced liver fibrosis. In view of the therapeutic potential of adipose-derived stem cells (ADSCs), we investigated whether ADSCs transplantation has the ability to control or reverse fibrosis progression in the liver of Echinococcus multilocularis (E. multilocularis) infected mice. METHODOLOGY/PRINCIPAL FINDINGS: C57BL/6 mice infected with E. multilocularis through portal vein inoculation were intravenously injected with ADSCs isolated from inguinal adipose tissues of 6-8 weeks old mice. Histopathological analysis including heamatoxylin & eosin staining as well as Masson's trichrome staining, and Sirius red staining were performed to access the degree of liver fibrosis. Histopathological examination 30 days after ADSCs transplantation revealed that ADSCs significantly decreased the degree of liver fibrosis in E. multilocularis infected mice by inhibiting the expressions of α-SMA and type 1 collagen deposition. In addition, compared to the non-transplanted group, ADSCs transplantation reduced fibrotic areas in E. multilocularis infected mice. We also found that ADSCs transplantation significantly down-regulated TGF-ß1 and TGF-ßR expressions, while up-regulating Smad7 expression in the TGF-ß/Smad signaling pathway. CONCLUSIONS: ADSCs can alleviate Echinococcus multilocularis infection-induced liver fibrosis by modulating the activity level of the TGF-ß/Smad7 signaling pathway and provide a potential therapeutic approach for E. multilocularis-induced fibrosis.

An improved experimental method for simultaneously isolating hepatocytes and hepatic stellate cells in mouse liver infected with Echinococcus multilocularis.

BACKGROUND: Alveolar echinococcosis (AE) is a zoonotic disease caused by the larval stage of Echinococcus multilocularis parasitizing in the human liver, causing local pathological changes in the liver and manifesting as hyperplasia, liver fibrosis, atrophy, degeneration, and necrosis. Here, we report a method that can simultaneously isolate hepatocytes and hepatic stellate cells (HSCs) from mice infected with Echinococcus multilocularis. METHODS: A mouse model of AE was established. Hepatocytes and HSCs were isolated from mouse liver using a two-step method combining in situ collagenase perfusion and gradient centrifugation. Expressions of Alb, Desmin, and α-SMA were detected with immunofluorescence to identify the isolated hepatocytes and HSCs. RESULTS: The viability and purity of hepatocytes and HSCs both reached 90% or above. For hepatocytes, clear cell boundaries were observed, and the nuclei were round or oval, with clear nucleoli. There was a homogeneous distribution of the hepatocyte marker Alb in the cytoplasm of hepatocytes. Lipid droplets and Desmin expression were observed in the cytoplasm of freshly isolated HSCs. During the activation of HSCs, the lipid droplets gradually decreased and disappeared with a high expression of α-SMA. CONCLUSION: Hepatocytes and HSCs are simultaneously isolated. This may provide a research tool to investigate the interaction between hepatocytes and HSCs and to investigate the mechanism of Echinococcus multilocularis infection-induced liver pathological changes.

Red foxes harbor two genetically distinct, spatially separated Echinococcus multilocularis clusters in Brandenburg, Germany.

BACKGROUND: Alveolar echinococcosis (AE) is a clinically serious zoonosis caused by the fox tapeworm Echinococcus multilocularis. We studied the diversity and the distribution of genotypes of E. multilocularis isolated from foxes in Brandenburg, Germany, and in comparison to a hunting ground in North Rhine-Westphalia. METHODS: Echinococcus multilocularis specimens from 101 foxes, 91 derived from Brandenburg and 10 derived from North Rhine-Westphalia, were examined. To detect potential mixed infections with different genotypes of E. multilocularis, five worms per fox were analyzed. For genotyping, three mitochondrial markers, namely cytochrome c oxidase subunit 1 (Cox1), NADH dehydrogenase subunit 1 (Nad1), and ATP synthase subunit 6 (ATP6), and the nuclear microsatellite marker EmsB were used. To identify nucleotide polymorphisms, the mitochondrial markers were sequenced and the data were compared, including with published sequences from other regions. EmsB fragment length profiles were determined and confirmed by Kohonen network analysis and grouping of Sammon's nonlinear mapping with k-means clustering. The spatial distribution of genotypes was analyzed by SaTScan for the EmsB profiles found in Brandenburg. RESULTS: With both the mitochondrial makers and the EmsB microsatellite fragment length profile analyses, mixed infections with different E. multilocularis genotypes were detected in foxes from Brandenburg and North Rhine-Westphalia. Genotyping using the mitochondrial markers showed that the examined parasite specimens belong to the European haplotype of E. multilocularis, but a detailed spatial analysis was not possible due to the limited heterogeneity of these markers in the parasite population. Four (D, E, G, and H) out of the five EmsB profiles described in Europe so far were detected in the samples from Brandenburg and North Rhine-Westphalia. The EmsB profile G was the most common. A spatial cluster of the E. multilocularis genotype with the EmsB profile G was found in northeastern Brandenburg, and a cluster of profile D was found in southern parts of this state. CONCLUSIONS: Genotyping of E. multilocularis showed that individual foxes may harbor different genotypes of the parasite. EmsB profiles allowed the identification of spatial clusters, which may help in understanding the distribution and spread of the infection in wildlife, and in relatively small endemic areas.

Epidemiological and Clinical Characteristics of Alveolar Echinococcosis: An Emerging Infectious Disease in Alberta, Canada.

Human alveolar echinococcosis (AE) is a zoonotic cestode infection which is usually fatal in the absence of treatment. Treatment involves major surgery or indefinite antiparasitic therapy. The incidence is rising in Europe and Asia, with an increased risk observed in immunocompromised individuals. Previously, AE acquisition in North America was extremely rare, except for one remote Alaskan Island. Recent studies have demonstrated a new European-like strain of Echinococcus multilocularis (Em) in wildlife and in human AE in western Canada. We report the experience of all AE patients diagnosed in Alberta. Each was diagnosed by histopathology, serology, and PCR-confirmed by a reference laboratory. Seventeen cases of human AE, aged 19-78 years, nine females, were diagnosed between 2013 and 2020: all definitely or probably acquired in Alberta. Six lived in urban areas, and 14 had kept dogs. In eight, the lesions were found incidentally on abdominal imaging performed for other indications. Six were immunocompromised to varying degrees. Six were first diagnosed at surgery. All have been recommended benzimidazole therapy. One died of surgical complications. Clinicians should be aware of this diagnostic possibility in patients presenting with focal nonmalignant hepatic mass lesions. Greater urbanization of coyotes, the predominant definitive host of Em in Alberta, and growing numbers of immune suppressed individuals in the human population may lead to increasing recognition of AE in North America.

Overview of Echinococcus multilocularis in Turkey and in the World

Echinococcus multilocularis, a heteroxen and zoonotic parasite, is found in the intestine of carnivores, particularly foxes. Adult cestodes are regarded apathogenic in definitive hosts, while metacestode, the alveolar form, is high pathogenic for intermediate hosts. The alveolar cyst causes a maling tumor-like lesions with infiltrative, proliferative and destructive character which locates in the liver primarily, then metastasizes to other organs. If it is not treated in intermediate hosts it causes irreversible symtoms and death after located in vital organs such as liver, lungs, brain. Humans are infected by oral uptake of the viable eggs, accidentally. Because its life-cycle depends on relationship between hunter and hunting, endemic areas of the parasite are limited. The cestoda is found only in the Northern Hemisphere, while some countries are regarded high-endemic, such as Turkey. However, there is a few study on epidemiology of the parasite in Turkey, except human cases. In the review, data on the distribution of E. multilocularis in definitive and intermediate hosts in the world are presented, and the situation of the parasite in Turkey has been evaluated in detail.

Enhanced Oral Bioavailability and Anti-Echinococcosis Efficacy of Albendazole Achieved by Optimizing the "Spring" and "Parachute".

Maximizing the pharmacological efficacy of albendazole (ABZ), an anti-echinococcosis drug, is essential in the long-term treatment of patients with echinococcosis. As a weakly alkaline drug, ABZ has a pH-dependent solubility that decreases dramatically from gastric fluid (pH 1.4) to intestinal fluid (pH 6.5), where it is absorbed. In this study, we endeavored to develop an optimized tablet formulation of ABZ to improve its dissolution and oral bioavailability from two aspects: a faster initial dissolution in the gastric pH condition (i.e., the "spring") and a more prolonged drug supersaturation in the intestinal pH condition (i.e., the "parachute"). To achieve this goal, ABZ-HCl salt was selected first, which demonstrated a higher intrinsic dissolution rate under pH 1.4 compared with the ABZ free base that is used in the commercial product Albenda. Second, by comparing the ABZ supersaturation kinetics under pH 6.5 in the presence of various polymers including poly(vinylpyrrolidone) (PVP), PVP/VA, hydroxypropyl methylcellulose (HPMC), and HPMC acetate succinate (HPMC-AS), HPMC-AS was found to be the most effective crystallization inhibitor for ABZ, likely due to the hydrophobic interaction between ABZ and HPMC-AS in an aqueous environment. The newly designed tablet formulation containing ABZ-HCl and HPMC-AS showed ∼3 times higher oral bioavailability compared with that of Albenda in Beagle dogs. More significantly, the anti-echinococcosis efficacy of the improved formulation was 2.4 times higher than that of Albenda in a secondary hepatic alveolar echinococcosis Sprague-Dawley rat model. The strategy of simultaneously improving the spring and parachute of an oral formulation of ABZ, by using a highly soluble salt and an effective polymeric crystallization inhibitor, was once again proven to be a viable and readily translatable approach to optimize the unsatisfactory oral medicines due to solubility and bioavailability limitations.

Repurposing of an old drug: In vitro and in vivo efficacies of buparvaquone against Echinococcus multilocularis.

The metacestode stage of the fox tapeworm Echinococcus multilocularis causes the lethal disease alveolar echinococcosis. Current chemotherapeutic treatment options are based on benzimidazoles (albendazole and mebendazole), which are insufficient and hence alternative drugs are needed. In this study, we screened the 400 compounds of the Medicines for Malaria Venture (MMV) Pathogen Box against E. multilocularis metacestodes. For the screen, we employed the phosphoglucose isomerase (PGI) assay which assesses drug-induced damage on metacestodes, and identified ten new compounds with activity against the parasite. The anti-theilerial drug MMV689480 (buparvaquone) and MMV671636 (ELQ-400) were the most promising compounds, with an IC50 of 2.87 µM and 0.02 µM respectively against in vitro cultured E. multilocularis metacestodes. Both drugs suggested a therapeutic window based on their cytotoxicity against mammalian cells. Transmission electron microscopy revealed that treatment with buparvaquone impaired parasite mitochondria early on and additional tests showed that buparvaquone had a reduced activity under anaerobic conditions. Furthermore, we established a system to assess mitochondrial respiration in isolated E. multilocularis cells in real time using the Seahorse XFp Analyzer and demonstrated inhibition of the cytochrome bc1 complex by buparvaquone. Mice with secondary alveolar echinococcosis were treated with buparvaquone (100 mg/kg per dose, three doses per week, four weeks of treatment), but the drug failed to reduce the parasite burden in vivo. Future studies will reveal whether improved formulations of buparvaquone could increase its effectivity.

Biochemical Characterization of Echinococcus multilocularis Antigen B3 Reveals Insight into Adaptation and Maintenance of Parasitic Homeostasis at the Host-Parasite Interface.

Alveolar echinococcosis (AE) caused by Echinococcus multilocularis metacestode is frequently associated with deleterious zoonotic helminthiasis. The growth patterns and morphological features of AE, such as invasion of the liver parenchyme and multiplication into multivesiculated masses, are similar to those of malignant tumors. AE has been increasingly detected in several regions of Europe, North America, Central Asia, and northwestern China. An isoform of E. multilocularis antigen B3 (EmAgB3) shows a specific immunoreactivity against patient sera of active-stage AE, suggesting that EmAgB3 might play important roles during adaptation of the parasite to hosts. However, expression patterns and biochemical properties of EmAgB3 remained elusive. The protein profile and nature of component proteins of E. multilocularis hydatid fluid (EmHF) have never been addressed. In this study, we conducted proteome analysis of EmHF of AE cysts harvested from immunocompetent mice. We observed the molecular and biochemical properties of EmAgB3, including differential transcription patterns of paralogous genes, macromolecular protein status by self-assembly, distinct oligomeric states according to individual anatomical compartments of the worm, and hydrophobic ligand-binding protein activity. We also demonstrated tissue expression patterns of EmAgB3 transcript and protein. EmAgB3 might participate in immune response and recruitment of essential host lipids at the host-parasite interface. Our results might contribute to an in depth understanding of the biophysical and biological features of EmAgB3, thus providing insights into the design of novel targets to control AE.

Successful intestinal Echinococcus multilocularis oncosphere invasion and subsequent hepatic metacestode establishment in resistant RccHan™:WIST rats after pharmacological immunosuppression.

Susceptibility/resistance to larval Echinococcus multilocularis infection varies greatly depending on host species and strains. Whereas several mice strains and non-human primates are highly susceptible to alveolar echinococcosis, rats and most of humans are considered as more resistant. In this study, we aimed to elucidate factors responsible for host resistance in rats (Experiments A-D). (A) The parasite establishment was not observed in immunocompetent Wistar rats orally inoculated with sodium hypochlorite resistant eggs with/without pig bile, or activated/non-activated oncospheres (NAO). Peritoneal inoculation with NAO or metacestode tissue allowed the parasite establishment in rats. (B) T-cell-deficient athymic nude rats showed complete resistance against the metacestode establishment after oral inoculation with parasite eggs. This finding suggests that T-cell-independent parasite clearance occurred in the animals during early phase of the parasite invasion. Finally, Wistar rats that received pharmacological immunosuppression using either dexamethasone (DMS) alone or methotrexate (MTX) i.p. alone or a combination of these compounds were orally inoculated with the parasite's eggs. As a result (D), successful establishment of metacestode with protoscoleces was observed in all 3 rats treated with DMS (s.c.) alone or in all 6 rats treated with DMS (s.c.) plus MTX but not in 8 rats with MTX alone, suggesting that factors affected by DMS treatment are responsible to regulate the parasite invasion and establishment.

Competence of hosts and complex foraging behavior are two cornerstones in the dynamics of trophically transmitted parasites.

Multi-host trophically transmitted parasite (TTP) is a common life cycle where prey and predators are respectively intermediate and definitive hosts of the parasite. In these systems, the foraging response of the predator toward variations in prey community composition underlies the dynamic of the parasite. Therefore, modeling epidemiological dynamic of infectious diseases considering ecological predator-prey interactions is essential to understand the spreading of parasites in ecosystems. However, two important weaknesses of previous TTP models including feeding interaction can be pointed out: (i) the choice of a linear density-dependent contact rate is faintly realistic as it supposes an unlimited ingestion rate with an increase of prey density and (ii) considering only one host prey species prevents the study of host biodiversity effect due to change in the prey community composition where species have different competences to be infected and to transmit the parasite. This article attempts to address the dynamics of parasite in a context of multiple intermediate hosts differentiated by their competences and of complex foraging behavior of the predator. We present and analyze a deterministic one predator-two prey model, which is then used to explore the transmission cycle of the cestode Echinococcus multilocularis. This study examines the foraging condition for the co-existence of the prey, and then, based on the computation of the threshold measure of disease risk, R0, we show that the pattern of feeding interactions changes the relationship between disease risk and prey community composition. Finally, we disentangle the mechanism leading to the counter-intuitive observation of a decrease of disease risk while the population density of intermediate hosts increases.

Alveolar echinococcosis: how knowledgeable are primary care physicians and pharmacists in the Franche-Comté region of France?

BACKGROUND: Alveolar echinococcosis (AE) is a parasitic disease resulting from the intrahepatic growth of Echinococcus multilocularis larva. This zoonotic helminthic disease is rare but, if left untreated or treated too late, can be severe or even fatal. In France, endemic areas containing infected foxes have become larger, spreading towards western regions of the country and leading to an increased risk of environmental contamination. An observational survey was undertaken in 2014 to assess the level of knowledge of AE among primary care physicians (PCPs) and pharmacists in the Franche-Comté region. METHODS: Standardized questionnaires were sent to a random sample of 183 PCPs and 236 pharmacists practicing in the Franche-Comté region (eastern France), requesting their voluntary and anonymous participation. The questionnaires collected socio-demographic details, self-evaluation and asked multiple choice questions (MCQs) about epidemiology, prevention, diagnosis and management of AE. RESULTS: The crude response rate was 37.5% of the PCPs and pharmacists questioned. Responses to MCQs showed that most of the participating PCPs and pharmacists had acceptable basic knowledge of AE, especially concerning epidemiology and prevention of the disease. However, a serious lack of knowledge was observed concerning the management of AE. CONCLUSION: PCPs are often the first health professionals to suspect latent AE, which is still a rural disease in France. Both PCPs and pharmacists play an important role in informing and referring patients potentially exposed to AE. This study shows that although AE is rare, PCPs and pharmacists of the Franche-Comté region have a satisfactory level of knowledge of AE.

A Newly Discovered Epidemic Area of Echinococcus multilocularis in West Gansu Province in China.

Alveolar echinococcosis (AE) is a lethal parasitic disease. In Gansu Province of China, all AE cases reported in literature were from Zhang and Min Counties, the southern part of the province. Here, we report the discovery of nine AE cases and one cystic echinococcosis (CE) case from Nanfeng Town of Minle County, in the middle of Hexi Corridor in west Gansu Province. The diagnosis of these cases were confirmed by serology, histopathology, computed tomography, B-ultrasound, immunohistochemistry method, DNA polymerase chain reaction and sequencing analysis. Because eight of nine AE cases came from First Zhanglianzhuang (FZLZ) village, we conducted preliminary epidemiological analyses of 730 persons on domestic water, community and ecology such as 356 dogs' faeces of FZLZ, in comparison with those of other five villages surrounding FZLZ. Our studies indicate that Nanfeng Town of Minle County is a newly discovered focus of AE in China as a CE and AE co-epidemic area. Further research of Echinococcus multilocularis transmission pattern in the area should be carried for prevention of this parasitic disease.

Suppression of E. multilocularis hydatid cysts after ionizing radiation exposure.

BACKGROUND: Heavy-ion therapy has an advantage over conventional radiotherapy due to its superb biological effectiveness and dose conformity in cancer therapy. It could be a potential alternate approach for hydatid cyst treatment. However, there is no information currently available on the cellular and molecular basis for heavy-ion irradiation induced cell death in cystic echinococcosis. METHODODOLOGY/PRINCIPAL FINDINGS: LD50 was scored by protoscolex death. Cellular and ultrastructural changes within the parasite were studied by light and electron microscopy, mitochondrial DNA (mtDNA) damage and copy number were measured by QPCR, and apoptosis was determined by caspase 3 expression and caspase 3 activity. Ionizing radiation induced sparse cytoplasm, disorganized and clumped organelles, large vacuoles and devoid of villi. The initial mtDNA damage caused by ionizing radiation increased in a dose-dependent manner. The kinetic of DNA repair was slower after carbon-ion radiation than that after X-rays radiation. High dose carbon-ion radiation caused irreversible mtDNA degradation. Cysts apoptosis was pronounced after radiation. Carbon-ion radiation was more effective to suppress hydatid cysts than X-rays. CONCLUSIONS: These studies provide a framework to the evaluation of attenuation effect of heavy-ion radiation on cystic echinococcosis in vitro. Carbon-ion radiation is more effective to suppress E. multilocularis than X-rays.

Immune responses on allograft heart transplantation in inbred rats infected with Echinococcosis multilocularis.

BACKGROUND: Alveolar echinococcosis (AE) is caused by the metacestode stage of Echinococcus multilocularis (E. multilocularis) and is a rare but life-threatening disease. This disease commonly is characterized by an infiltrative, tumor-like growth of the E. multilocularis metacestode in the liver of human. Liver transplantation is an effective therapy for end-stage of hepatic AE, but the characteristics of host immunity associated with E. multilocularis infection with organ transplantation are poorly defined. We hereby aimed to study the immunological status and allograft heart survival in inbred rats with E. multilocularis infection. METHODS: Rat models of AE were established by injecting the E. multilocularis suspension made from E. multilocularis infected tissues into the abdomen of Lewis (LEW) rats. Three months later, in the experimental group, allograft heart transplantation was performed from Brown-Norway (BN) rats to the E. multilocularis infected LEW rats. In the control group, we transplanted hearts from BN rats to healthy LEW rats. The influence of the disturbed immune system in E. multilocularis infected rats on the heart transplantation was assessed, including observation of allograft heart survival time, histopathological examination of grafts and immunohistochemical examination of infiltrating cells (CD4(+) T cells, CD8(+) T cells and eosinophile granulocytes), measurement of interleukin (IL)-4 and interferon (IFN)-γ in the serum by enzyme-linked immunosorbent assay (ELISA) and analysis of CD4(+)CD25(+) regulatory T cells in peripheral blood by fluorescence activated cell sorting (FACS) flow cytometric analysis. RESULTS: The survival time of recipients in the experimental group was prolonged compared with those in the control group. The numbers of graft infiltrating CD8(+) T cells were decreased whereas the graft infiltrating eosinophil granulocytes (CD15(+)) were increased in grafts in the experimental group (P < 0.05). Furthermore, the proportion of CD4(+)CD25(+) regulatory T cells in the peripheral blood was 10.8% on average in the experimental group, which was significantly higher than that in the control group (6.1%). In addition, the level of serum IL-4 in E. multilocularis infected rats was higher than that in the control group rats, whereas the level of serum IFN-γ in experimental group was lower than that in the control group when graft rejection occurred (P < 0.05). CONCLUSIONS: This study suggests that E. multilocularis infection could prolong the allograft survival time through the polarization of Th1/Th2-type cells and induction of CD4(+)CD25(+) regulatory T cells. This strategy may provide a new idea for establishing transplantation tolerance.

The impact of globalisation on the distribution of Echinococcus multilocularis.

In the past three decades, Echinococcus multilocularis, the cause of human alveolar echinococcosis, has been reported in several new countries both in definitive hosts (canids) as well as in people. Unless treated, infection with this cestode in people is fatal. In previously endemic countries throughout the Northern Hemisphere, geographic ranges and human and animal prevalence levels seem to be increasing. Anthropogenic influences, including increased globalisation of animals and animal products, and altered human/animal interfaces are thought to play a vital role in the global emergence of this pathogenic cestode. Molecular epidemiological techniques are a useful tool for detecting and tracing introductions, and differentiating these from range expansions.

Excretory/secretory-products of Echinococcus multilocularis larvae induce apoptosis and tolerogenic properties in dendritic cells in vitro.

BACKGROUND: Alveolar echinococcosis, caused by Echinococcus multilocularis larvae, is a chronic disease associated with considerable modulation of the host immune response. Dendritic cells (DC) are key effectors in shaping the immune response and among the first cells encountered by the parasite during an infection. Although it is assumed that E.multilocularis, by excretory/secretory (E/S)-products, specifically affects DC to deviate immune responses, little information is available on the molecular nature of respective E/S-products and their mode of action. METHODOLOGY/PRINCIPAL FINDINGS: We established cultivation systems for exposing DC to live material from early (oncosphere), chronic (metacestode) and late (protoscolex) infectious stages. When co-incubated with Echinococcus primary cells, representing the invading oncosphere, or metacestode vesicles, a significant proportion of DC underwent apoptosis and the surviving DC failed to mature. In contrast, DC exposed to protoscoleces upregulated maturation markers and did not undergo apoptosis. After pre-incubation with primary cells and metacestode vesicles, DC showed a strongly impaired ability to be activated by the TLR ligand LPS, which was not observed in DC pre-treated with protoscolex E/S-products. While none of the larvae induced the secretion of pro-inflammatory IL-12p70, the production of immunosuppressive IL-10 was elevated in response to primary cell E/S-products. Finally, upon incubation with DC and naïve T-cells, E/S-products from metacestode vesicles led to a significant expansion of Foxp3+ T cells in vitro. CONCLUSIONS: This is the first report on the induction of apoptosis in DC by cestode E/S-products. Our data indicate that the early infective stage of E. multilocularis is a strong inducer of tolerance in DC, which is most probably important for generating an immunosuppressive environment at an infection phase in which the parasite is highly vulnerable to host attacks. The induction of CD4+CD25+Foxp3+ T cells through metacestode E/S-products suggests that these cells fulfill an important role for parasite persistence during chronic echinococcosis.

Suppression of acute rejective response following orthotopic liver transplantation in experimental rats infected with Echinococcus multilocularis.

BACKGROUND: Hepatic alveolar echinococcosis (AE) is a parasitic disease in humans and caused by the Echinococcus multilocularis (Em). Orthotopic liver transplantation (OLT) may be the only effective treatment for end-stage hepatic AE. However, in some AE patients, extrahepatic Em can not be completely eliminated after OLT. We aimed to study whether the immunological changes caused by Em evasion may influence the rejective response. METHODS: Rat modles of AE were established by injecting the Em suspension into abdomen of Brown Norway (BN) rats. Three months later, in the experimental group, the liver was transplanted from Lewis (LEW) rats to Em-infected BN rats. In the control group, transplantation was from LEW rats to healthy BN rats. Liver tissue and peripheral blood (PB) samples were collected on days 1, 3, 5, and 7 after OLT. Liver tissue was analyzed after hematoxylin and eosin (H&E) staining; numbers of CD4, CD8, and CD28 on peripheral blood cells were detected by flow cytometry; and expression of the chemokine fractalkine (Fkn) was detected by reverse transcription PCR (RT-PCR). Interleukin-10 (IL-10) was measured in the serum by enzyme-linked immunosorbent assay (ELISA). In every group, eight BN rats were retained for observing survival time. RESULTS: The survival times of recipients in the experimental group were prolonged compared with those in the control group. The rejective response occurred later and was milder in the experimental group. percentage of CD4, CD8, CD28 T-cells and Fkn mRNA expression were lower in the experimental group. While the serum IL-10 levels were higher in the experimental group than those in the control group. CONCLUSIONS: Acute rejective response after OLT was attenuated in the rats with Em infection, and the recipients` survival time was prolonged. Em may play a role in this process by elevating IL-10 secretion, decreasing the effector T cells, inhibiting the expression of Fkn, which lead to reduce the inflammatory cells infiltration into the liver.