Identification and characterisation of molecules involved in the pathogenicity of Entamoeba histolytica
Final Report Abstract
One possibility to get an idea about molecules involved in the pathogenicity of Entamoeba histolytica is a direct comparison of pathogenic and non-pathogenic isolates. Recently, we generated twelve clones (A1-A12) derived from the non-pathogenic isolate HM-1:IMSS-A and twelve clones (B1-B12) derived from the pathogenic isolate HM-1:IMSS-B and compared in their ability to induce amoebic liver abscesses (ALAs) in gerbils. All A-clones are found to be non-pathogenic, whereas beside the clone B1, B8, B11 and B12 which produced very small or no ALAs, all B-clones are pathogenic. The nonpathogenic clones A1 and B8 and the pathogenic clone B2 were selected for further analyses. Comparison of their transcriptomes revealed a differentially expression of 76 genes between clone A1 and clone B2 (30 genes upregulated and 46 downregulated in clone B2, respectively), and a differentially expression of 14 genes between clone B8 and B2 (4 genes upregulated and 10 genes downregulated in clone B2, respectively). Only six genes were found to be regulated the same way between the two non-pathogenic clones and the pathogenic clone. In total the influence of 27 highest differentially expressed genes were analysed for their influence on ALA formation using transfectants where the genes of interest are overexpressed or silenced. For at least six of the analysed genes an influence on ALA formation was observed. Most of them encode for hypothetical proteins, but also an alcohol dehydrogenase and a metallo peptidase could be identified. Beside pathogenicity factors of the parasite, also host-specific mechanisms may determine the clinical outcome of the disease. Therefore, a comparative transcriptome analysis of murine livers after infection with the clones A1, B2 and B8 was performed. Interestingly, an increased expression of genes coding for the cholesterol, lipid- and steroid metabolism were identified in mice infected with the non-pathogenic clone A1 in comparison to the two B-clones. However, nearly no differences were observed after infection with the non-pathogenic clone B8 and pathogenic clone B2. All results point to the direction, that amoebae of clone A1 were detected much faster by the host immune system and induce a stronger defence reaction in comparison to amoebae of clone B2. However, the reason for the loss of pathogenicity of clone B8 could not be resolved so far. Cysteine peptidases are discussed to be involved in ALA formation of E. histolytica. In this context we identified three cysteine peptidases that can restore the pathogenic phenotype of the non-pathogenic clone A1 after overexpression of the respective genes (ehcp-b8, -b9, and -c13). This finding reinforces the importance of cysteine peptidases as pathogenicity factors of E. histolytica. In addition, three methods were established that enable a more detailed study of amoebic gene expression, amoebic surface proteins and amoebic motility in vivo.
Publications
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(2013) Overexpression of specific cysteine peptidases confers pathogenicity to a nonpathogenic Entamoeba histolytica clone. mBio, 4, e00072-13
Matthiesen, J., Bär, A.-K., Bartels, A.-K., Marien, D., Ofori, S., Biller, L., Tannich, E., Lotter, H., Bruchhaus, I.
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(2014) The cell surface proteome of Entamoeba histolytica. Mol Cell Prot., 13, 132-44
Biller, L. , Matthiesen, J. , Kühne, V., Lotter, H., Handal, G., Nozaki, T., Saito-Nakano, Y., Schümann, M., Roeder, T., Tannich, E., Krause, E., Bruchhaus, I.
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(2015) Magnetic resonance imaging of pathogenic protozoan parasite Entamoeba histolytica labeled with superparamagnetic iron oxide nanoparticles. Invest Radiol. 50,709-718
Ernst, T.M. , Fehling, H., Bernin, H., Zaruba, M.D., Bruchhaus, I., Adam, G., Ittrich, H., Lotter H.
