title: Analysis of α-synuclein expression in lymphocytes of healthy donors and patients with sporadic Parkinson's disease
Creators: name: Himmelsbach, Felicia
Publisher: name: Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU)
Year: 2024
Subjects: subject: alpha synuclein, Parkinson's disease, lymphocytes

description: Background and Aims Parkinson’s disease (PD) is one of the most common neurodegenerative movement diseases primarily affecting the elderly population. PD`s main symptoms - rigor, tremor, and brady- or akinesia - go back to a loss of dopaminergic neurons (DN) in the substantia nigra (SN) pars compacta of the midbrain. DN loss is closely connected with an occurrence of intracellular α-Synuclein (aSyn)-containing protein aggregates – known as Lewy bodies (LB) or Lewy neurites (LN) – and their spreading over the human central nervous system (CNS). The disease was first described in 1817, but still poses various challenges in diagnosis as well as in therapy, even though modern medicine has developed several approaches to pharmacological as well as non-pharmacological symptomatic treatment by now. A causative treatment, however, has not been found up until today. The immune system, consisting of different types of leucocytes as well as of non-cellular defence mechanisms, plays a crucial role in both, acute and chronic diseases and is involved in PD pathology. Preceding studies already showed that there are certain observable reciprocal effects between age, health condition, immune system activation and aSyn expression. Rooting in the main hypothesis that aSyn is expressed in human lymphocytes, my research focused on the questions whether and how aSyn expression rates differ in different lymphocyte subsets, and what influence donor age, health condition and the activation status of the respective cell type might have on aSyn expression. I aimed for a better understanding of the development of PD on the cellular level, because this may offer valuable approaches to the diagnosis and treatment of the disease in the future. Methods Lymphocyte subsets were separated under the use of magnetic, cluster of differentiation (CD)-specific beads. Subsequently, activation of the various T cell subsets was conducted by applying specific T cell activation beads (DynaBeads). For observation of aSyn expression on the transcript level, multiple real-time polymerase chain reactions (rtPCR) were conducted, while for observation of the protein level, protein resolubilisation methods were evaluated as well as a combination of intracellular aSyn staining with CD-specific surface staining for fluorescence-activated cell sorting (FACS) analysis. Expression rates on the transcript and protein levels were compared among different lymphocyte subsets of various age groups and an active and at a resting state. Eventually, aSyn expression of PD patients` cells was compared with that of healthy individuals. Results While aSyn protein expression analysis in human lymphocytes only offered a perspective of what should be evaluated further in the future, rtPCR analysis allowed an interesting insight in PD pathology on the aSyn transcript level. We were able to show that in activated CD4+ T cells, expression of aSyn transcript seemed to decrease in comparison to that of resting cells – an observation, which was observable in all donor groups, young and healthy, older and healthy and PD patients. Furthermore, aSyn transcript expression showed a correlation with the respective donor age. aSyn transcript expression was on average higher in CD4+ T cells of older and healthy individuals than in those of young and healthy individuals. On the other side, PD patients’ CD4+ T cells appeared to express less aSyn transcript levels than those of healthy individuals. Discussion It was shown that aSyn expression in human lymphocytes depends on various influential factors. Age, health condition and the activation state of the respective lymphocytes are important influences on aSyn expression. Those observations give us an idea on how PD might be influenced by activation mechanisms in the human immune system. Our present results appear to contradict the hypothesis of PD as a systemic autoimmune reaction and rather support the theory of a focal inflammatory origin of PD pathomechanism. Further immunological research on cellular mechanisms of aSyn transcript and protein expression as well as regulation might be the future key to an earlier diagnosis of PD and, maybe, also for the treatment or even prevention of the disease.