Neurodegeneration, oxidative stress and lipid metabolism plasma biomarkers to differentiate Parkinson's disease from atypical parkinsonian syndromes

INTRODUCTION

The identification of blood biomarkers appears to be a means of improving diagnosis accuracy in Parkinson's disease (PD) and atypical parkinsonian syndromes (APS). We, therefore, evaluate the performance of neurodegeneration, oxidative stress and lipid metabolism plasma biomarkers to distinguish PD from APS.

METHODS

This was a monocentric study with a cross-sectional design. Plasma levels and discriminating power of neurofilament light chain (NFL), malondialdehyde (MDA) and 24S-Hydroxycholesterol (24S-HC) were assessed in patients with clinical diagnoses of PD or APS.

RESULTS

In total, 32 PD cases and 15 APS cases were included. Mean disease durations were 4.75 years in PD group and 4.2 years in APS group. Plasma levels of NFL, MDA and 24S-HC differed significantly between the APS and PD groups (P=0.003; P=0.009; P=0.032, respectively). NFL, MDA and 24S-HC discriminated between PD and APS (AUC=0.76688; AUC=0.7375; AUC=0.6958, respectively). APS diagnosis significantly increased with MDA level≥23.628nmol/mL (OR: 8.67, P=0.001), NFL level≥47.2pg/mL (OR: 11.92, P<0.001) or 24S-HC level≤33.4pmol/mL (OR: 6.17, P=0.008). APS diagnosis considerably increased with the combination of NFL and MDA levels beyond cutoff values (OR: 30.67, P<0.001). Finally, the combination of NFL and 24S-HC levels, or MDA and 24S-HC levels, or all three biomarkers' levels beyond cutoff values systematically classified patients in the APS group.

CONCLUSION

Our results suggest that 24S-HC and especially MDA and NFL could be helpful for differentiating PD from APS. Further studies will be needed to reproduce our findings on larger, prospective cohorts of patients with parkinsonism evolving for less than 3 years.

Hemodialysis reduces plasma apolipoprotein C-I concentration making VLDL a better substrate for lipoprotein lipase

Apolipoprotein Cs (apoC-1, apoC-II, and apoC-III) are lipoprotein components that have regulatory effects on enzymes involved in lipoprotein metabolism. Owing to their low molecular weights, apoCs can adsorb onto and/or pass through dialysis membranes. Our study determines the consequence of hemodialysis (HD) on plasma concentrations of apoCs and on the activities of enzymes modulated by apoCs. Plasma samples were collected from 28 patients with chronic renal failure before and after HD. Plasma apoC-II levels were unchanged, whereas apoC-III levels were slightly decreased in post-dialysis plasmas. The apoC-I content was markedly reduced during HD. This was due to a significant decrease in the apoC-I content of very low-density lipoprotein (VLDL), whereas the apoC-I content of high-density lipoprotein (HDL) was unchanged. Although HDL bound apoC-I is thought to inhibit cholesterol ester transfer protein, no change in the ability of pre- and post-dialysis VLDL to interact with the transfer protein were observed. Complementary experiments confirmed that VLDL-bound apoC-I has no transfer protein inhibitory potential. In contrast, an increase in the ability of post-dialysis apoC-I-poor VLDL to act as substrate for lipoprotein lipase (LPL) was found compared to pre-dialysis VLDL. Our study shows that apoC-I losses during HD might be beneficial by improving the ability of VLDL to be a substrate for LPL thus improving plasma triglyceride metabolism.