Biosketch

Sahar El Aidy received her PhD in 2012 and has extensive experience in studying the gut microbiota, its metabolic activity, and its interactions with the host; the latter is in connection to both the host’s immune system and neurological functioning. Her research group focuses on studying the chemical signals that are produced through the microbial breakdown of food and medication, which help the microbes to live in symbiosis with their host and withstand harsh competition among each other.

Three top publications 2017-2022

1. van Kessel SP, Frye AK, …….., van Dijk G & El Aidy S (2019) Gut bacterial tyrosine decarboxylases restrict levels of levodopa in the treatment of Parkinson's disease. Nature Communications 10(1): 310; DOI: https://doi.org/10.1038/s41467-019-08294-y

This study characterizes the ability of gut-associated bacteria to convert levodopa to dopamine via tyrosine decarboxylases (TDC). The findings indicate that bacterial TDC efficiently convert levodopa to dopamine, even in the presence of tyrosine, the main substrate for the bacterial enzyme, and that high abundance of this gut bacterial enzyme in patients with Parkinson's disease compromises levels of levodopa. The study also shows that the higher relative abundance of bacterial tdc at the site of levodopa absorption has a significant impact on levels of levodopa in the plasma of rats. Overall, the results highlight the role of microbial metabolism in drug availability, specifically that the abundance of bacterial TDC in the proximal small intestine can explain the increased dosage regimen of levodopa treatment in Parkinson's disease patients.

2. van Kessel SP, Auvinen P, Scheperjans F & El Aidy S (2021) Gut bacterial tyrosine decarboxylase associates with clinical variables in a longitudinal cohort study of Parkinsons disease. npj Parkinsons Disease 7(1): 115; DOI: https://doi.org/10.1038/s41531-021-00260-0

This study investigates the potential association between anti-Parkinson's disease drug exposure and bacterial tyrosine decarboxylating (TDC) gene abundance over a period of two years in a longitudinal cohort of PD patients and healthy controls. The findings highlight significant associations between tdc-gene abundance, several anti-PD medications (entacapone, rasagiline, pramipexole, and ropinirole), and gastrointestinal symptoms. These results suggest that increased exposure to anti-PD medication could affect the abundance of bacterial TDC and ultimately impact drug efficacy. The study urges the need to better understand the mechanisms through which drug-microbiota interactions occur.

3. van Kessel SP, Bullock A, van Dijk G & El Aidy S (2022) Parkinson's disease medication alters small intestinal motility and microbiota composition in healthy rats. mSystems 7(1): e0119121; DOI: https://doi.org/10.1128/msystems.01191-21

This study investigates the effect of Parkinson's disease medication on the gastrointestinal function and microbiota composition, specifically at the site of drug absorption, the small intestine. The study was conducted on healthy rats treated with dopamine agonists, pramipexole, or ropinirole, and the results showed a significant reduction in small intestinal motility and an increase in bacterial overgrowth in the distal small intestine. Findings from this study also revealed microbial changes that were similar to those observed in human PD versus healthy control microbiota studies. Overall, the study highlights the significant impact of commonly prescribed PD medication on the gastrointestinal motility and microbiota composition, irrespective of the disease itself.