Identification of the bacterial metabolite aerugine as potential trigger of human dopaminergic neurodegeneration

Environment International
2023
Ückert Anna-Katharina
Ückert Anna-Katharina, Rütschlin Sina, Gutbier Simon, Wörz Nathalie Christine, Miah Mahfuzur R., Martins Airton C., Hauer Isa, Holzer Anna-Katharina, Meyburg Birthe, Mix Ann-Kathrin, Hauck Christof, Aschner Michael, Böttcher Thomas, Leist Marcel
https://www.sciencedirect.com/science/article/pii/S0160412023005020
DOI: 10.1016/j.envint.2023.108229
PMID: 37797477
Keyword: bacterial toxin · caenorhabditis elegans · dopaminergic neurodegeneration · ferroptosis · Parkinson’s disease · streptomyces venezuelae

Abstract

The causes of nigrostriatal cell death in idiopathic Parkinson’s disease are unknown, but exposure to toxic chemicals may play some role. We followed up here on suggestions that bacterial secondary metabolites might be selectively cytotoxic to dopaminergic neurons. Extracts from Streptomyces venezuelae were found to kill human dopaminergic neurons (LUHMES cells). Utilizing this model system as a bioassay, we identified a bacterial metabolite known as aerugine (C10H11NO2S; 2-[4-(hydroxymethyl)-4,5-dihydro-1,3-thiazol-2-yl]phenol) and confirmed this finding by chemical re-synthesis. This 2-hydroxyphenyl-thiazoline compound was previously shown to be a product of a wide-spread biosynthetic cluster also found in the human microbiome and in several pathogens. Aerugine triggered half-maximal dopaminergic neurotoxicity at 3-4 µM. It was less toxic for other neurons (10-20 µM), and non-toxic (at <100 µM) for common human cell lines. Neurotoxicity was completely prevented by several iron chelators, by distinct anti-oxidants and by a caspase inhibitor. In the Caenorhabditis elegans model organism, general survival was not affected by aerugine concentrations up to 100 µM. When transgenic worms, expressing green fluorescent protein only in their dopamine neurons, were exposed to aerugine, specific neurodegeneration was observed. The toxicant also exerted functional dopaminergic toxicity in nematodes as determined by the “basal slowing response” assay. Thus, our research has unveiled a bacterial metabolite with a remarkably selective toxicity toward human dopaminergic neurons in vitro and for the dopaminergic nervous system of Caenorhabditis elegans in vivo. These findings suggest that microbe-derived environmental chemicals should be further investigated for their role in the pathogenesis of Parkinson’s disease.