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Mechanisms of Cryptosporidium Parvum Invasion Using an Improved Human Epithelial Cell Model

Varughese, Eunice A
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1447688891

Abstract Details

2015, PhD, University of Cincinnati, Medicine: Toxicology (Environmental Health).
Cryptosporidiosis is an environmentally-associated human diarrheal disease caused by the etiological agent, Cryptosporidium. This parasitic pathogen is an intestinal protozoan that is abundant in the environment as highly resistant oocysts and can cause life-threatening consequences in immunosuppressed individuals. Of the various species found in the environment, one of the human-infective species is Cryptosporidium parvum. Parasite development and propagation occurs within a unique intracellular but extracytoplasmic parasitophorous vacuole at the apical surface of intestinal epithelial cells. Very little is known regarding the pathogenesis of C. parvum and what host factors are involved in infection. In order to assess differences in host susceptibilities, we compared several different host cell types using an in vitro model. Specifically, we introduced a new small intestinal epithelial cell type, FHs 74 Int, which supported better infection of C. parvum. Moreover, this cell type sustained the development and growth of the parasite over 48 hours. The molecular mechanisms of Cryptosporidium pathogenesis and the factors that cause variation in infection are poorly understood. Two different intestinal epithelial cells, HCT-8 and FHs 74 Int, had drastically different levels of infections, with the first supporting much less infection than the second. Using the FHs 74 Int model, we studied the expression patterns of several host factors before and after infection to C. parvum. One protein of interest was the tyrosine phosphatase Src homology-2 domain-containing phosphatase 2 (SHP-2). SHP-2, encoded by the human PTPN11 gene, is a ubiquitously expressed protein tyrosine phosphatase that acts on paxillin. In this study, we found that SHP-2 co-localizes at the apical end of the C. parvum infection site. Moreover, inhibition of SHP-2 abrogated complete infection and decreased phosphorylated levels of another protein-of-interest, paxillin. Paxillin is moderately dephosphorylated upon C. parvum infection, although total paxillin levels do not change. Paxillin is localized to focal complexes, where it participates as one of the components that connect the host cytoskeleton with receptors, such as integrin. Paxillin phosphorylation often promotes cell motility or migration of the cell, whereas dephosphorylation results in stronger adhesion to the extra-cellular matrix. This may be a countermeasure by the parasite to prevent turnover and removal of infected cells from the intestine, and thus provide a stable replicative/development niche. These findings provide further evidence of the involvement of the host cytoskeleton during infection and a possible pathway for the parasite to create a niche for its own survival and development in the intestine.
Jagjit Yadav, Ph.D. (Committee Chair)
Susan Kasper, Ph.D. (Committee Member)
Susan Waltz, Ph.D. (Committee Member)
Ying Xia, Ph.D. (Committee Member)
102 p.
Environmental Health
Cryptosporidium; SHP-2; in vitro; FHs 74 Int; parasitology; pathogenesis

Recommended Citations

Citations

  • Varughese, E. A. (2015). Mechanisms of Cryptosporidium Parvum Invasion Using an Improved Human Epithelial Cell Model [Doctoral dissertation, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1447688891

    APA Style (7th edition)

  • Varughese, Eunice. Mechanisms of Cryptosporidium Parvum Invasion Using an Improved Human Epithelial Cell Model. 2015. University of Cincinnati, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1447688891.

    MLA Style (8th edition)

  • Varughese, Eunice. "Mechanisms of Cryptosporidium Parvum Invasion Using an Improved Human Epithelial Cell Model." Doctoral dissertation, University of Cincinnati, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1447688891

    Chicago Manual of Style (17th edition)

ucin1447688891
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This open access ETD is published by University of Cincinnati and OhioLINK.