University of Twente Student Theses


The role of α-synuclein in the gastrointestinal tract in Parkinson’s disease

Bunningen, Imke van (2023) The role of α-synuclein in the gastrointestinal tract in Parkinson’s disease.

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Abstract:Parkinson’s disease (PD) is the second most common neurodegenerative disease worldwide(Dorsey et al., 2018). The past decays a wealth of evidence has witnessed that the gastrointestinal system (GIT) and the Gut-Brain-Axis (GBA) are at least to some extent involved in PD pathology (Anis et al., 2022; Rao & Gershon, 2016a; Rietdijk et al., 2017; Schaeffer et al., 2020). Lewy Bodies (LBs) are a prominent biomolecular feature of PD(Kalia & Lang, 2015). These LBs are neuronal protein aggregates, termed amyloids, mainly composed of the α-synuclein protein (Fricova et al., 2020; Schaeffer et al., 2020). In healthy conditions α-synuclein occurs in an unfolded conformation in the cytosol or in association with cellular membranes(Emamzadeh, 2016). It is thought that once misfolded the protein can act as template and force other native proteins to fold in a similar pathogenic structure. In this way the protein can incite a chain-reaction of protein misfolding and aggregation into LBs(Jucker & Walker, 2013). Protein structures that may act as potent templates to induce aggregation are named seeds(Jucker & Walker, 2013). Lewy pathology (LP) in PD is not restricted to the brain but can also be found in the spinal cord and some parts of the peripheral nervous system including the enteric nervous system (ENS)(Braak et al., 2003). Whether the presence of LP and α-synuclein in the ENS is clinically relevant in the course of PD is a topic of ongoing research. This project aims to determine the effects of α-synuclein exposure at the intestinal epithelial barrier. To this end, the effect of direct amyloid exposure on intestinal epithelial barrier health was tested by stimulating a monolayer of Caco-2 cells, which are often used as intestinal model cells, with α-synuclein monomers, seeds or fibrils. Monomers had no significant effect on cell viability. On the contrary, in contrast to expectations, low concentrations of seeds combined with monomers or fibrils alone (50 – 1000 nM) increased cell viability. However, these observations need to be confirmed in additional experiments. Before the cell viability experiments, it was sought to set-up a simple PD model which would enable to determine the effects of neuronal α-synuclein secretion at intestinal epithelial barrier functioning. To this end, neuroblastoma SH-SY5Y were differentiated by addition of retinoic acid (RA) into a more mature neuronal phenotype. SH-SY5Y cells are an immortalized cell line frequently used to study neurodegenerative mechanisms. Analysis of neuronal marker β-III-tubulin revealed significant neuritic process formation after RA-mediated differentiation. Finally, the use of a simple set-up of LP and the intestinal epithelial barrier was investigated. This Transwell-based set-up consisted of confluent Caco-2 monolayers in the apical compartment and SH-SY5Y overexpressing α-synuclein wild-type (wt) in the basolateral compartment. Some first experiments were performed to test potential model pitfalls. From these it could be concluded that the applied set-up required optimization before use in PD research.
Item Type:Essay (Master)
Faculty:TNW: Science and Technology
Subject:44 medicine
Programme:Biomedical Engineering MSc (66226)
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