Association between plasminogen activator inhibitor-1 gene polymorphisms and susceptibility to Parkinson's disease in Chinese patients

Serum Levels of Plasminogen Activator Inhibitor-1 in Patients with Parkinson's Disease

OBJECTIVES

The aim of the study was to investigate serum plasminogen activator inhibitor-1 (PAI-1) levels of patients with Parkinson's disease (PD) and their relationship with clinical findings and treatment of disease.

METHODS

The study included 125 PD patients and 48 healthy controls. Patients have been taking effective dopaminergic treatment regularly. The clinical severity of parkinsonism was assessed using the Hoehn and Yahr (HY) staging scale and the Unified PD Rating Scale (UPDRS). PAI-1 level analysis was performed by enzyme-linked immunosorbent assay.

RESULTS

Patients with PD had significantly lower serum PAI-1 levels than healthy controls (p < 0.001). Correlations with clinical findings showed only a marginally positive correlation between serum PAI-1 and HY score (r = 0.170, p = 0.05). In contrast, no significant correlation was demonstrated with the UPDRS score or other clinical parameters.

CONCLUSION

This is the first comprehensive analysis of serum PAI-1 levels in patients with PD. The distribution of PAI-1 in PD appears to be complex. The study results implicate that the paradoxical effects of tissue plasminogen activator on the brain parenchyma can be important in the pathophysiology of PD. Future studies are needed to elucidate the role of fibrinolytic system components in PD.

MAPKAPK2, a potential dynamic network biomarker of α-synuclein prior to its aggregation in PD patients

One of the important pathological features of Parkinson's disease (PD) is the pathological aggregation of α-synuclein (α-Syn) in the substantia nigra. Preventing the aggregation of α-Syn has become a potential strategy for treating PD. However, the molecular mechanism of α-Syn aggregation is unclear. In this study, using the dynamic network biomarker (DNB) method, we first identified the critical time point when α-Syn undergoes pathological aggregation based on a SH-SY5Y cell model and found that DNB genes encode transcription factors that regulated target genes that were differentially expressed. Interestingly, we found that these DNB genes and their neighbouring genes were significantly enriched in the cellular senescence pathway and thus proposed that the DNB genes HSF1 and MAPKAPK2 regulate the expression of the neighbouring gene SERPINE1. Notably, in Gene Expression Omnibus (GEO) data obtained from substantia nigra, prefrontal cortex and peripheral blood samples, the expression level of MAPKAPK2 was significantly higher in PD patients than in healthy people, suggesting that MAPKAPK2 has potential as an early diagnostic biomarker of diseases related to pathological aggregation of α-Syn, such as PD. These findings provide new insights into the mechanisms underlying the pathological aggregation of α-Syn.

Molecular and Cellular Interactions in Pathogenesis of Sporadic Parkinson Disease

An increasing number of the population all around the world suffer from age-associated neurodegenerative diseases including Parkinson’s disease (PD). This disorder presents different signs of genetic, epigenetic and environmental origin, and molecular, cellular and intracellular dysfunction. At the molecular level, α-synuclein (αSyn) was identified as the principal molecule constituting the Lewy bodies (LB). The gut microbiota participates in the pathogenesis of PD and may contribute to the loss of dopaminergic neurons through mitochondrial dysfunction. The most important pathogenetic link is an imbalance of Ca²⁺ ions, which is associated with redox imbalance in the cells and increased generation of reactive oxygen species (ROS). In this review, genetic, epigenetic and environmental factors that cause these disorders and their cause-and-effect relationships are considered. As a constituent of environmental factors, the example of organophosphates (OPs) is also reviewed. The role of endothelial damage in the pathogenesis of PD is discussed, and a ‘triple hit hypothesis’ is proposed as a modification of Braak’s dual hit one. In the absence of effective therapies for neurodegenerative diseases, more and more evidence is emerging about the positive impact of nutritional structure and healthy lifestyle on the state of blood vessels and the risk of developing these diseases.

Exogenous Tetranectin Alleviates Pre-formed-fibrils-induced Synucleinopathies in SH-SY5Y Cells by Activating the Plasminogen Activation System

Parkinson's disease (PD) is a common neurodegenerative disease. Previously we identified tetranectin (TN) as a differentially expressed protein in the cerebrospinal fluid of PD patients, and we were surprised to find that TN knockout mice developed PD features. However, the specific role of TN in PD has not been clarified. In this study, we aimed to determine the effect of exogenous TN on cellular PD models and elucidate the underlying mechanisms. We found that exogenous TN could alleviate pre-formed-fibrils (PFFs)-induced synucleinopathies in SH-SY5Y cells and reduce the cell-to-cell transmission of α-synuclein (SYN). We also found that TN can promote the degradation of SYN by plasmin, which may account for its effect on cellular PD models. Moreover, administration of SYN/PFFs decreased the expression of TN and increased the expression of plasminogen activator inhibitor-1 (PAI-1) in SH-SY5Y cells, thereby reducing plasmin activity. Our findings depict a possible SYN-TN-plasmin interaction in which elevated levels of extracellular SYN monomers and aggregates in PD diminish the production of TN and PAI-1. Such changes lead to a reduced plasmin activity, which in turn reduces the degradation of extracellular SYN, thus forming a vicious cycle.