Skin Biopsy For Assessment Of Autophagy Dysregulation In The Pathogenesis Of Parkinson’s Disease

BackgroundParkinson’s disease was first systematically described by James Parkinson in1817, who named it the ‘shaking palsy’. PD is a progressive neurodegenerative disorder commonly in the elderly, with increasing incidence with age. The patients’ average age was often over60years old. Clinical features of Parkinson’s disease comprise the classical triad of bradykinesia, static tremor and rigidity, in association with important changes in posture. The pathologic hallmarks of PD are progressive degeneration of dopaminergic neurons within pars compacta of the substantia nigra and the appearance of Lewy bodies. The cause of PD is unknown by now. Evidence suggests that environmental neurotoxins, aging, mutant proteins and dysregulation of ubiquition proteasome pathway may contribute to mitochondrial dysfunction and increasing cellular oxidative stress, all of which have been implicated in the aetiopathogenesis of PD. A vast amount of evidence points to that autophagy dysregulation is an essential part in disease development, eventually leading to cellular toxicity and neurodegeneration. Autophagy as a potiental cause of PD is currently attracting more and more attention. Autophagy, which means ‘self-eating’, is a lysosome degradation pathway by which cells capture intracellular proteins, impaired organelles, and deliver them to lysosomal compartment where they are degraded. It plays an important role in cells and keeps the metabolic balance. Autophagy is classified into3types: macroautophagy, chaperone-mediated autophagy (CMA), and macroautophagy. The specific mechanism of autophagy in the process of PD remains unknown by now. Autophagy may participates in the degradation of α-synuclein, endoplasmic reticulum stress and in the turnover of mitochondria. Autophagy dysfunction also represents an important pathogenic mechanism of cell death in PD. Moreover, PD related genes, such as LRRK2、PINK1、parkin、DJ-1also play a role in the process of PD by impairing the function of autophagy or/and mitochondria. A lot of researchs detected the autophagy activity only by postmortern autopsy or establishing the cell and animal models, but few studies detected the function of autophagy in vivo.Objective1．To assessment the function of macroautophagy and chaperone-mediated autophagy (CMA) in skin of patients with Parkinson’s disease by skin biopsy.2．To explore the role of autophagy in pathogenesis of Parkinson’s disease. Methods1．The study samples included23PD patients and23normal controls. Clinical data of all PD patients were collected, and graded by Hoehn&Yahr scales. skin biopsies were taken from PD patients.2．Skin biopsy specimens were immunohistochemically stained with anti-LC3, anti-Beclin-1, anti-HSC70and anti-LAMP2a antibodies. The expression of microtubule-associated protein1light chain3(LC-3), Beclin-1, heat shock cognate protein70(HSC-70），lysosome-associated membrane protein2a(LAMP-2a) were detected by Western blot.3．Statistical analysis was performed using the SPSS17.0. We compared the variable by means of the LSD-t test or Wilcoxon rank test. A level of significance of p<0.05was used.Results1．The propotion of Beclin-1、LC3immune positive cells and the optical density of these cells in skin of PD were significantly higher than that of the healthy controls. Western blot results showed LC3II/LC3I, Beclin-1expression were significantly higher than that of control subjects (p<0.05).2. The propotion of LAMP2a、HSC70immune positive cells and the optical density of these cells in skin of PD were significantly more than that of the healthy controls. Western blot results showed LAMP2a、HSC70expression were significantly higher than that of control subjects (p<0.05). Conclusions1．Macroautophagy activity was higher in PD patients skin, and dysregulation of macroautophagy may take place in the skin of PD patients and participate in the process of PD.2.Chaperone-mediated autophagy was induced in PD patients skin, and dysregulation of chaperone-mediated autophagy may take place in the skin of PD patients and play a role in the pathogenesis of PD.