Potential role of ochratoxin A in Parkinson's disease: a systematic review of current evidence.

Ochratoxin A (OTA) is a mycotoxin produced by Aspergillus and Penicillium species that contaminates various food and feed products, presenting potential risks to human health. While OTA is well-known for its nephrotoxic effects, emerging evidence highlights its neurotoxic potential. Parkinson's disease (PD) is a neurodegenerative disorder with both genetic and environmental aetiologies. Emerging lines of investigation have focused their research on the role of environmental toxins, including mycotoxins, in PD pathogenesis. However, the specific involvement of OTA in PD-related pathways still needs to be unravelled. This systematic review compiles and evaluates OTA neurotoxicity studies according to the adverse outcome pathway (AOP) for PD, established by the Organisation for Economic Cooperation and Development (OECD). The AOP framework outlines a series of key event (KEs) beginning with mitochondrial Complex I (CI) inhibition and progressing through mitochondrial dysfunction, impaired proteostasis, dopaminergic neuron degeneration, neuroinflammation, and resulting in parkinsonian motor deficits. In this systematic review, a comprehensive literature search was conducted in PubMed, to identify studies evaluating OTA neurotoxic effects. Using a search strategy of 19 terms and following a two-phased study selection, 30 relevant studies were retrieved, of which 16 dealt with in vitro adult neurotoxicity (ANT), 13 focused on in vivo ANT, and 1 gave both in vitro and in vivo approaches. Authors agree that in vitro and in vivo exposure to OTA causes mitochondrial dysfunction, impaired proteostasis, degeneration of dopaminergic (DA) neurons, and neuroinflammation. However, a notable absence of research remains on the molecular initiating event (MIE), binding to CI, and on KE1, inhibition of CI. This review identifies critical research gaps and highlights the need for further mechanistic studies on the impact of OTA on neurodegenerative pathways, particularly its binding and inhibition of CI, as well as mechanisms related to KE3: impaired proteostasis. Addressing these gaps may provide valuable insights into OTA neurotoxic potential and its relevance in PD-like neurodegeneration.