Parkinson’s disease (PD) is the most common α-synucleinopathy worldwide. The pathognomonic hallmark of PD is the misfolding and propagation of the α-synuclein (α-syn) protein, observed in post-mortem histopathology. It has been hypothesized that α-synucleinopathy triggers oxidative stress, mitochondrial dysfunction, neuroinflammation, and synaptic dysfunction, leading to neurodegeneration. To this date, there are no disease-modifying drugs that generate neuroprotection against these neuropathological events and especially against α-synucleinopathy. Growing evidence suggests that peroxisome proliferator-activated receptor (PPAR) agonists confer neuroprotective effects in PD, however, whether they also confer an anti-α-synucleinopathy effect is unknown. Here we analyze the reported therapeutic effects of PPARs, specifically the gamma isoform (PPARγ), in preclinical PD animal models and clinical trials for PD, and we suggest possible anti-α-synucleinopathy mechanisms acting downstream from these receptors. Elucidating the neuroprotective mechanisms of PPARs through preclinical models that mimic PD as closely as possible will facilitate the execution of better clinical trials for disease-modifying drugs in PD.

Dysfunction of cellular homeostasis can lead to misfolding of proteins thus acquiring conformations prone to polymerization into pathological aggregates. This process is associated with several disorders, including neurodegenerative diseases, such as Parkinson’s disease (PD), and endoplasmic reticulum storage disorders (ERSDs), like alpha-1-antitrypsin deficiency (AATD) and hereditary hypofibrinogenemia with hepatic storage (HHHS). Given the shared pathophysiological mechanisms involved in such conditions, it is necessary to deepen our understanding of the basic principles of misfolding and aggregation akin to these diseases which, although heterogeneous in symptomatology, present similarities that could lead to potential mutual treatments. Here, we review: (i) the pathological bases leading to misfolding and aggregation of proteins involved in PD, AATD, and HHHS: alpha-synuclein, alpha-1-antitrypsin, and fibrinogen, respectively, (ii) the evidence linking each protein aggregation to the stress mechanisms occurring in the endoplasmic reticulum (ER) of each pathology, (iii) a comparison of the mechanisms related to dysfunction of proteostasis and regulation of homeostasis between the diseases (such as the unfolded protein response and/or autophagy), (iv) and clinical perspectives regarding possible common treatments focused on improving the defensive responses to protein aggregation for diseases as different as PD, and ERSDs.

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La enfermedad de Parkinson es el segundo trastorno neurodegenerativo más común a nivel mundial para el cual no hay un tratamiento curativo. Esta patología se caracteriza por síntomas motores, los cuales se deben en gran medida a la muerte de un tipo específico de células en nuestro cerebro: las neuronas dopaminérgicas, llamadas así por su capacidad para producir el neuromodulador dopamina. Existe evidencia de que en esta pérdida celular participa de manera muy importante la proteína alfa-sinucleína (α-sin). En este texto, nos enfocaremos en revisar dos acercamientos de estudios recientes que buscan nuevas opciones de tratamiento para la enfermedad de Parkinson. Primeramente, se discuten los estudios que buscan la posibilidad de restituir los niveles de dopamina, partiendo del diseño de nanopartículas novedosas que regulen su estabilidad y liberación. Por otro lado, revisaremos las investigaciones dirigidas a conocer si el proceso de co-liberación de neurotransmisores, como el glutamato, podría conferir a las neuronas dopaminérgicas protección contra la agregación de α-sin. Aunque se requieren más investigaciones en el área, los avances hasta ahora son prometedores, y el desarrollo de tratamientos más eficaces para esta patología podrían estar más cerca de lo que pensamos.