30th Annual Meeting of the German Society for Parasitology

Tolerance induction in the liver

Keynote

Spatial Transcriptomics of parasites – 2D transcriptome analyses of tissues in the liver fluke Fasciola hepatica

Abstract text Introduction Fasciolosis is a food-borne trematode infection, caused by the liver fluke Fasciola hepatica and related species. The disease has considerable impact on human and animal health worldwide and costs the global livestock industry several billions of dollars per year. Limited therapeutic options and increasing anthelminthic resistance complicate sustainable control and highlight the need for novel anthelmintics. Objectives In order to identify new drug targets, it is first necessary to better understand the fluke"s biology, including its organ function and organ-specific gene expression. The cutting-edge technology Spatial Transcriptomics (ST) allows studying gene expression in a new dimension. Material &amp; Methods Here, we applied Visium Spatial Gene Expression Solution (10x Genomics) on adult F. hepatica. Results Our ST data enables us to visualize gene expression in 2D, according to the original morphological context. This provides insights into tissue-specific gene expression throughout the fluke"s body. Gene expression profiles for eight different tissues, such as intestine, tegument and reproductive organs were identified and selected marker genes were validated by in situ hybridization. Gene ontology (GO) enrichment analysis revealed characteristic biological processes and molecular functions associated with each cluster. Finally, some genes with interesting spatial expression patterns were selected for functional characterization using RNA interference. Conclusion Taken together, this work provides the first spatial transcriptome of a parasitic flatworm. The dataset facilitates the design of further experiments that aim at characterizing tissue-specific gene function. Some of these genes may serve as new potential drug targets to better treat fasciolosis in the future.

Molecular Parasitology

Talk

Prof.

Three species of foodborne trematodes: a comparative RNAseq analysis of the hamster liver

Abstract text The foodborne trematodes Opisthorchis felineus, O. viverrini and Clonorchis sinensis induce liver fluke infections in mammals, including humans. The species have different carcinogenic potential: O. viverrini and C. sinensis are assigned to Group 1A of biological carcinogens, while O. felineus belongs to Group 3A. To provide in-depth research and to gain insights into the species-specific mechanism by which liver fluke infections cause liver lesions we investigated differential gene expression of liver transcriptomes (Illumina HiSeq2500) of golden hamsters infected with O. felineus, O. viverrini and C. sinensis at 1 and 3 months postinfection. The libraries contained 905,079,329 sequences (average 37,711,638.7 reads per sample). The STAR aligner, DESeq2, clusterProfiler and BisqueRNA R-packages were applied. Principal components analysis revealed high clustering of samples by species and by the time in infection. In C. sinensis infection, the highest number (2886) differentially expressed genes (DEGs) were observed. Whereas O. felineus and O. viverrini infections change the expression of 1790 and 1501 DEGs, respectively. Cluster analysis revealed that activated cellular pathways were different between acute and chronic infection. Transcriptomic data were supported by the results of western blotting, revealing the presence of fibrogenesis-related proteins. DEGs were enriched by common MSigDB signatures such as myogenesis, inflammatory response, late estrogen response, IL2 STAT5 signaling, TNFA signaling via NFKB for all three infections. Epithelial-to-mesenchymal transition, IL6 JAK STAT3 signaling, and TGFB signaling were represented in C. sinensis and O. felineus- infected hamster, but not after O. viverrini infection. Common enriched KEGG pathways were Hippo, PI3K-Akt and calcium signaling pathways, while PPAR signaling pathway was present only in C. sinensis and O. viverrini infections. Significant interspecies differences in the response of cholangiocytes, stellate cells and M1 macrophages were found. Our data provide knowledge about species-specific changes in gene expression in the liver fluke–infected host liver and contribute to understanding the biliary fibrosis and neoplasia associated with liver fluke infections. This work was supported by the Russian Science Foundation [grant number 22-24-20010].

Food-borne Parasitose

Parasite-Host Interaction

Mass spectrometry-based analysis of proteome and lipidome reveals liver metabolic reprogramming induced by Schistosoma mansoni infection

Abstract text Introduction Schistosomiasis is a neglected tropical disease estimated to affect at least 236 million people from 78 countries. However, the underlying mechanisms of intestinal and hepatic schistosomiasis caused by the species Schistosoma mansoni are complex and still not fully elucidated. Mass spectrometry (MS) as an analytical technique is becoming increasingly important in bioscience, quickly analyzing the molecular composition of a sample, helping to determine the chemical composition and addressing complex biological problems. Objectives We investigated the hepatic proteome and lipidome composition of S. mansoni infected hamsters. We aim to uncover differentially regulated hepatic constituents in the context of S. mansoni infection to identify characteristically altered key molecules involved in hepatic metabolism modulation. Materials &amp; Methods We applied MS-based accurate quantitative proteomic and lipidomic analysis to define molecular pathways involved in hepatic schistosomal infection. We also subjected liver tissue of infected hamsters to high-resolution AP-SMALDI mass spectrometry imaging (MSI) to visualize the lipid distribution in tissue sections with high lateral resolution. Results The disease provoked enormous alterations in the expression of liver proteomes and lipidomes. In the infected livers, the regulated molecules are involved in various biological functions such as immune response, cytoskeleton reorganization, apoptotic signaling, energy-generating, and a broad range of biosynthetic/metabolic processes. We also characterized several markers specific to the infection by AP-SMALDI MSI and exhibited their distribution in the tissue sections. Conclusion The mass spectrometric analysis of the liver samples indicates a characteristic regulation of the hepatic metabolism during schistosomiasis. Our findings expand the knowledge about biological pathways that are regulated in the liver upon S. mansoni infection and furthermore provide information that may also serve for diagnostic purposes. In summary, the combination of MS techniques used in our study demonstrates the potential of this combined approach to enlarge our understanding of the complex pathologies caused by host-parasite interactions.

Univ.-Prof. Dr. rer. nat.

Liver-dependent protective immune responses against Ascaris infections

Abstract text Introduction: The liver is an effected organ of different parasites whether it is protozoan or helminth infections. Even so for both human and porcine Ascaris infections, which affect &gt; 0.7 billion humans in the global south and lead to huge economic losses in the pig farming, respectively. In fact, larval stages of Ascaris when migrating through the liver are taking advantage of the tolerogenic environment hepatic tissue provides. However, concomitantly, the formation of pathological lesions in the liver, known as white spots, also suggests a strong liver immune response and inflammation lead to elimination of the parasites during the initial phase of larval migration.Objectives: In this research project, we aim to determine whether resistance to Ascaris larval migration occurs in the liver and whether liver innate immune cells are involved in the elimination of Ascaris larvae or are targets of immunoregulation by the parasite.Materials &amp; methods: To address this, we infected two different mouse strains with Ascaris that mimic hepato-tracheal migration of natural hosts but show contrasting susceptibilities to Ascaris infection. We immunologically analyzed liver innate immune cells such as innate lymphocytes, eosinophils, neutrophils and macrophages (MO) to determine their composition and phenotype during liver and lung stage of an Ascaris infection.Results: Our results show, resistant CBA mice harbor significantly less Ascaris suum larvae in the liver during liver stage of infection compared to susceptible C57BL/6 mice. Interestingly, hepatic resistance against Ascaris larval migration was associated with differences in polarization of liver MO. Already intrinsically, the frequencies of alternatively activated MO were elevated in the liver of the resistant strain in comparison to susceptible strain. Interestingly, Ascaris infection led to a hepatic downregulation of this host protective M2 macrophage response. Simultaneously, both mouse strains showed increased iNOS expression in liver MO which suggest larval clearance might be partly associated with a type 1 response but not being an effective host protective response as in the susceptible strain significant amounts of larvae were detectable despite iNOS production.Conclusion: Alternative activation of MO in liver seems to be associated with resistance and being actively counterregulated by infection. In contrast, iNOS production of liver macrophages is induced but ineffective in Ascaris larval killing.

Parasite Immunology

Highly functional Th2 effector cells coexist with IFN-g competent Th2/1 hybrid cells in the liver of nematode infected mice

Abstract text Introduction The small intestinal nematode Heligmosoides polygyrus establishes chronic infections in most mouse lines despite the induction of strong Th2 responses. We previously identified IFN-g competent Th2/1 hybrid cells as confounders of effective type 2 immunity in H. polygyrus infected mice and showed recently that age- and genotype-dependent differences in resistance to the infection correlate with the proportion of Th2/1 hybrid cells in nematode-induced CD4+GATA-3+ T cells. Objectives Th2/1 hybrid cells are relatively rare in the gut draining lymph nodes but may account for about half of the GATA-3+ effector cells in spleen and blood. We therefore investigated which other sites might serve as sources for nematode induced Th2/1 cells. Materials and methods We used the Heligmosoides polygyrus model for studying immune responses to helminth in C57BL/6 mice. A multi-color flowcytometric technique, as well as other enzyme-linked assay was also used to investigate the expression of type 1 and 2 immune markers on T cells after ex vivo cultures. Results We observed large numbers of GATA-3+ cells accumulating in the liver early during infection. These were enriched in Th2/1 cells, maintained during memory formation, and rapidly reactivated upon challenge infection in drug cured mice. Fitting the strong hepatic accumulation of CXCR3+ Th2/1 cells, myeloid cells isolated from the liver of infected mice stood out in the spontaneous production of the CXCR3-ligand CXCL9. Conclusion Together, these data suggest that IFN-g released early during worm infection results in the induction and systemic accumulation of IFN-g-competent type 2 effector cells. Whether spleen and liver limit excessive hybrid responses via apoptosis or benefit from Th2/1 accumulation in the surveillance of microbial translocation in enteric nematode infection is under current investigation.

Workshop I
GRK 2046 – Liver: A gatekeeper for parasite invasion

Appointment

Chairs

Programme

Workshop IGRK 2046 – Liver: A gatekeeper for parasite invasion

Appointment

Chairs

Programme

Workshop I
GRK 2046 – Liver: A gatekeeper for parasite invasion