A r t i c l e sThe dog tapeworm E. granulosus is one of a group of medically important parasitic helminths of the family Taeniidae (Platyhelminthes; Cestoda; Cyclophyllidea) that infect at least 50 million people globally 1 . Its life cycle involves two mammals, including an intermediate host, usually a domestic or wild ungulate (humans are accidental intermediate hosts) and a canine-definitive host, such as the domestic dog. The larval (metacestode) stage causes hydatidosis (cystic hydatid disease; cystic echinococcosis), a chronic cyst-forming disease in the intermediate (human) host. Currently, up to 3 million people are infected with E. granulosus 2,3 , and, in some areas, 10% of the population has detectable hydatid cysts by abdominal ultrasound and chest X-ray 4,5 .E. granulosus has no gut, circulatory or respiratory organs. It is monoecious, producing diploid eggs that give rise to ovoid embryos, the oncospheres. Strobilization is a notable feature of cestode biology, whereby proglottids bud distally from the anterior scolex, resulting in the production of tandem reproductive units exhibiting increasing degrees of development. A unique characteristic of the larvae (protoscoleces, PSCs) within the hydatid cyst is an ability to develop bidirectionally into an adult worm in the dog gastrointestinal tract or into a secondary hydatid cyst in the intermediate (human) host, a process triggered by bile acids 6 . Another distinct feature of E. granulosus is its capacity to infect and adapt to a large number of mammalian species as intermediate hosts, which has contributed to its cosmopolitan global distribution.Here we report the sequence and analysis of the E. granulosus genome. Comprising nine pairs of chromosomes 7 , it is one of the first cestode genomes to be sequenced and complements the recent publication by Tsai et al. 8 of a high-quality genome for Echinococcus multilocularis (the cause of alveolar echinococcosis), together with draft genomes of three other tapeworm species including E. granulosus. Our study provides insights into the biology, development, differentiation, evolution and host interaction of E. granulosus and has identified a range of drug and vaccine targets that can facilitate the development of new intervention tools for hydatid treatment and control. Cystic echinococcosis (hydatid disease), caused by the tapeworm E. granulosus, is responsible for considerable human morbidity and mortality. This cosmopolitan disease is difficult to diagnose, treat and control. We present a draft genomic sequence for the worm comprising 151.6 Mb encoding 11,325 genes. Comparisons with the genome sequences from other taxa show that E. granulosus has acquired a spectrum of genes, including the EgAgB family, whose products are secreted by the parasite to interact and redirect host immune responses. We also find that genes in bile salt pathways may control the bidirectional development of E. granulosus, and sequence differences in the calcium channel subunit EgCa v b 1 may be associated with praziquantel sens...

Immune checkpoint blockade has become a promising therapeutic approach to reverse immune cell exhaustion. Coinhibitory CD96 and T‐cell immunoglobulin and ITIM domain (TIGIT), together with costimulatory CD226, bind to common ligand CD155. The balancing between three receptors fine‐tunes immune responses against tumors. In this study, we investigated the expression of CD96, TIGIT, and CD226 in 55 fresh human hepatocellular carcinoma (HCC) samples, 236 paraffin‐embedded HCC samples, and 20 normal human livers. The cumulative percentage, absolute count, and mean fluorescence intensity (MFI) of CD96+ NK cells are significantly increased in the intratumoral tissues of HCC and break the balance between three receptors. Human CD96+ NK cells are functionally exhausted with impaired interferon‐gamma (IFN‐γ) and tumor necrosis factor‐alpha (TNF‐α) production, high gene expression of interleukin (IL)‐10 and transforming growth factor‐beta 1 (TGF‐β1), and low gene expression of T‐bet, IL‐15, perforin, and granzyme B. In addition, blocking CD96‐CD155 interaction specifically increases lysis of HepG2 cells by NK cells. HCC patients with a high level of CD96 or CD155 expression within tumor are strongly associated with deteriorating disease condition and shorter disease‐free survival (DFS) and overall survival times. Patients with a higher cumulative percentage of CD96+ NK cells within tumor also exhibit shorter DFS. High plasma level of TGF‐β1 in HCC patients up‐regulates CD96 expression and dynamically shifts the balance between CD96, TIGIT, and CD226 in NK cells. Blocking TGF‐β1 specifically restores normal CD96 expression and reverses the dysfunction of NK cells. Conclusion: These findings indicate that human intratumoral CD96+ NK cells are functionally exhausted and patients with higher intratumoral CD96 expression exhibit poorer clinical outcomes. Blocking CD96‐CD155 interaction or TGF‐β1 restores NK cell immunity against tumors by reversing NK cell exhaustion, suggesting a possible therapeutic role of CD96 in fighting liver cancer.

Cystic echinococcosis (CE) is a cosmopolitan zoonosis caused by the larval cystic stage of the dog tapeworm Echinococcus granulosus. This complex multicellular pathogen produces various antigens which modulate the host immune response and promote parasite survival and development. The recent application of modern molecular and immunological approaches has revealed novel insights on the nature of the immune responses generated during the course of a hydatid infection, although many aspects of the Echinococcus-host interplay remain unexplored. This paper summarizes recent developments in our understanding of the immunology and diagnosis of echinococcosis, indicates areas where information is lacking, and suggests possible new strategies to improve serodiagnosis for practical application.

Pathogenesis of chronically developing alveolar echinococcosis (AE) is characterized by a continuous, granulomatous, periparasitic infiltration of immune cells surrounding the metacestode of Echinococcus multilocularis (E.multilocularis) in the affected liver. A detailed cytokine and chemokine profile analysis of the periparasitic infiltrate in the liver has, however, not yet been carried out in a comprehensive way all along the whole course of infection in E. multilocularis intermediate hosts. We thus assessed the hepatic gene expression profiles of 18 selected cytokine and chemokine genes using qRT-PCR in the periparasitic immune reaction and the subsequent adjacent, not directly affected, liver tissue of mice from day 2 to day 360 post intra-hepatic injection of metacestode. DNA microarray analysis was also used to get a more complete picture of the transcriptional changes occurring in the liver surrounding the parasitic lesions. Profiles of mRNA expression levels in the hepatic parasitic lesions showed that a mixed Th1/Th2 immune response, characterized by the concomitant presence of IL-12α, IFN-γ and IL-4, was established very early in the development of E. multilocularis. Subsequently, the profile extended to a combined tolerogenic profile associating IL-5, IL-10 and TGF-β. IL-17 was permanently expressed in the liver, mostly in the periparasitic infiltrate; this was confirmed by the increased mRNA expression of both IL-17A and IL-17F from a very early stage, with a subsequent decrease of IL-17A after this first initial rise. All measured chemokines were significantly expressed at a given stage of infection; their expression paralleled that of the corresponding Th1, Th2 or Th17 cytokines. In addition to giving a comprehensive insight in the time course of cytokines and chemokines in E. multilocularis lesion, this study contributes to identify new targets for possible immune therapy to minimize E. multilocularis-related pathology and to complement the only parasitostatic effect of benzimidazoles in AE.

The discovery of CD49a þ liver-resident natural killer (NK) cells in mice alters our view of NK cells and provides another opportunity to study NK cells. Although evidence has suggested roles for NK cells in liver diseases, whether and how CD49a þ NK cells contribute to liver diseases remain unclear. In this study, we observed that accumulation of CD49a þ tissue-resident NK cells in human hepatocellular carcinoma (HCC) was higher than in peritumoral tissues. We studied the exhausted and regulatory phenotypes of CD49a þ tissue-resident NK cells by analysis of protein and mRNA. The proportion of CD49a þ NK cells was positively correlated to the proportion of NK cells expressing inhibitory receptors. In addition, CD49a þ NK cells expressed more of checkpoint molecules PD-1, CD96, and TIGIT. Transcriptomic analysis implicated CD49a þ tissue-resident NK cells in the negative regulation of immune responses. Comparison of murine and human CD49a þ NK cells revealed their distinct characteristics and functions. Finally, accumulation of tissue-resident CD49a þ NK cells in liver tumor was correlated to deteriorating disease condition and poor prognosis. Our findings show that CD49a þ NK cells accumulate in liver tumor and suggest a role for CD49a þ NK cells in the negative regulation of immune responses and the development of HCC.

The local immune mechanisms responsible for either self-healing or sustained chronic infection are not clear, in the development of E. multilocularis larvae. Here, we developed a suitable experimental model that mimics naturally infected livers, according to the parasite load. We demonstrated that local cellular immunity and fibrogenesis are actually protective and fully able to limit metacestode growth in the liver of low or medium dose-infected mice (LDG or MDG), or even to clear it, while impairment of cellular immunity is followed by a more rapid and severe course of the disease in high dose-infected mice (HDG). And recruitment and/ or proliferation of memory T cells (including CD4 Tem, CD8 Tcm and CD8 Tem) and imbalance of T1/T2/T17/Treg-type T cells in liver were not only associated with clearance of the parasite infection in LDG, but also with increased hepatic injury in HDG; in particular the dual role of CD8 T cells depending on the parasite load and the various stages of metacestode growth. Besides, we first demonstrate the association between LAG3- or 2B4-expressing T cells exhaustion and HD inocula in late stages. Our quantitative experimental model appears fully appropriate to study immunomodulation as a therapeutic strategy for patients with Alveolar Echinococcosis.

Alveolar echinococcosis (AE) is characterized by the development of irreversible fibrosis and of immune tolerance towards Echinococcus multilocularis (E. multilocularis). Very little is known on the presence of transforming growth factor-β (TGF-β) and other components of TGF-β/Smad pathway in the liver, and on their possible influence on fibrosis, over the various stages of infection. Using Western Blot, qRT-PCR and immunohistochemistry, we measured the levels of TGF-β1, TGF-β receptors, and down-stream Smads activation, as well as fibrosis marker expression in both a murine AE model from day 2 to 360 post-infection (p.i.) and in AE patients. TGF-β1, its receptors, and down-stream Smads were markedly expressed in the periparasitic infiltrate and also in the hepatocytes, close to and distant from AE lesions. Fibrosis was significant at 180 days p.i. in the periparasitic infiltrate and was also present in the liver parenchyma, even distant from the lesions. Over the time course after infection TGF-β1 expression was correlated with CD4/CD8 T-cell ratio long described as a hallmark of AE severity. The time course of the various actors of the TGF-β/Smad system in the in vivo mouse model as well as down-regulation of Smad7 in liver areas close to the lesions in human cases highly suggest that TGF-β plays an important role in AE both in immune tolerance against the parasite and in liver fibrosis.

Background and Aims The cestode Echinococcus multilocularis infection, a serious health problem worldwide, causes alveolar echinococcosis (AE), a tumor‐like disease predominantly located in the liver and able to spread to any organs. Until now, there have been few studies that explore how T‐cell exhaustion contributes to the parasite’s escape from immune attack and how it might be reversed. Approach and Results In this study, we found that liver T‐cell immunoreceptor with immunoglobulin and immunoreceptor tyrosine‐based inhibitory motif domain (TIGIT) expression was significantly enhanced and positively correlated with lesion activity in AE patients. High TIGIT expression in both liver‐infiltrating and blood T cells was associated with their functional exhaustion, and its ligand CD155 was highly expressed by hepatocytes surrounding the infiltrating lymphocytes. In co‐culture experiments using human blood T cells and hepatic cell line HL‐7702, CD155 induced functional impairment of TIGIT+ T cells, and in vitro blockade with TIGIT antibody restored the function of AE patients’ T cells. Similar TIGIT‐related functional exhaustion of hepatic T cells and an abundant CD155 expression on hepatocytes were observed in E. multilocularis–infected mice. Importantly, in vivo blocking TIGIT prevented T‐cell exhaustion and inhibited disease progression in E. multilocularis–infected mice. Mechanistically, CD4+ T cells were totally and CD8+ T cells partially required for anti‐TIGIT–induced regression of parasite growth in mice. Conclusions This study demonstrates that E. multilocularis can induce T‐cell exhaustion through inhibitory receptor TIGIT, and that blocking this checkpoint may reverse the functional impairment of T cells and represent a possible approach to immunotherapy against AE.