Objective: To delineate the influence of plasma and fecal short chain fatty acids (SCFAs) on the risk and severity of Parkinson’s disease (PD).

Background: Recent researches suggested the participation of gut microbial metabolites, SCFAs, in the pathogenesis of PD through gut-brain axis. However, whether they have beneficial or toxic effect on disease process is still unclear.

Method: We enrolled 96 PD patients and 85 age- and sex- matched healthy controls in our study. Disease severity was measured by Movement Disorder Society Unified Parkinson’s Disease Rating Scale (MDS-UPDRS) part III score for motor performance and Mini-Mental State Examination (MMSE) for cognitive function. The concentrations of fecal and plasma SCFAs, acetic acid, propionic acid and butyric acid, were quantified by gas/liquid chromatography-mass spectrometry. Multiple regression models were performed to assess the associations between SCFAs and the risk and severity of PD.

Results: After adjustment for age and sex, higher concentrations of plasma propionic acid (OR 14.4, 95%CI 1.63 – 159, P = 0.021) and butyric acid (OR 17.8, 95%CI 2.50 – 152, P = 0.006) were associated with increased PD risk. In contrast, lower levels of fecal acetic acid (OR 0.16, 95%CI 0.04 – 0.57, P = 0.006), propionic acid (OR 0.20, 95%CI 0.06 – 0.60, P = 0.006), and butyric acid (OR 0.27, 95%CI 0.10 – 0.67, P = 0.007) could predict PD development. Among PD patients, after correction for age, sex, disease duration and medication, higher MDS-UPDRS part III score correlated with higher plasma propionic acid levels (coefficient 24.4, 95%CI 1.00 – 47.7, P = 0.042) and increased plasma-to-stool ratio of propionic acid (coefficient 127231, 95%CI 63359 – 191103, P < 0.001) and butyric acid (coefficient 23521, 95%CI 10811 – 36230, P < 0.001). As for cognitive function, lower MMSE score was associated with higher plasma butyric acid (coefficient -11.7, 95%CI -21.9 – -1.44, P = 0.027) and lower fecal butyric acid (coefficient 2.95, 95%CI 0.60 – 5.31, P = 0.015) levels.

Conclusion: Our results demonstrated that higher plasma and reduced fecal concentrations of propionic acid and butyric acid correlated with increased PD risk and severity. These findings supported the role of gut-brain axis in PD pathogenesis and that altered metabolism of gut microbial metabolites with increased gut-to-blood penetration of propionic acid and butyric acid, may contribute to PD disease process.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/plasma-and-fecal-short-chain-fatty-acids-as-predictors-for-the-risk-and-severity-of-parkinsons-disease/