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Introduction The finding of mutations of the COQ2 gene and reduced coenzyme Q10 levels in the cerebellum in multiple system atrophy (MSA) suggest that coenzyme Q10 is relevant to MSA pathophysiology. Two recent studies have reported reduced coenzyme Q10 levels in plasma and serum (respectively) of MSA patients compared to Parkinson's disease and/or control subjects, but with largely overlapping values, limited comparison with other parkinsonisms, or dependence on cholesterol levels. We hypothesized that cerebrospinal fluid (CSF) is reliable to assess reductions in coenzyme Q10 as a candidate biomarker of MSA. Methods In this preliminary cross-sectional study we assessed CSF coenzyme Q10 levels in 20 patients with MSA from the multicenter Catalan MSA Registry and of 15 PD patients, 10 patients with progressive supranuclear palsy (PSP), and 15 control subjects from the Movement Disorders Unit Biosample Collection of Hospital Clinic de Barcelona. A specific ELISA kit was used to determine CSF coenzyme Q10 levels. CSF coenzyme Q10 levels were compared in MSA vs. the other groups globally, pair-wise, and by binary logistic regression models adjusted for age, sex, disease severity, disease duration, and dopaminergic treatment. Results CSF coenzyme Q10 levels were significantly lower in MSA than in other groups in global and pair-wise comparisons, as well as in multivariate regression models. Receiver operating characteristic curve analyses yielded significant areas under the curve for MSA vs. PD, PSP and controls. Conclusions These findings support coenzyme Q10 relevance in MSA. Low CSF coenzyme Q10 levels deserve further consideration as a biomarker of MSA.

One way to gain information about the fusogenic potential of virus-derived synthetic peptides is to examine their interfacial properties and subsequently to study them in monolayers and bilayers. Here, we characterize the physicochemical surface properties of the peptide E1(64–81), whose sequence is AQLVGELGSLYGPLSVSA. This peptide is derived from the E1 structural protein of GBV-C/HGV which was previously shown to inhibit leakage of vesicular contents caused by the HIV-1 fusion peptide (HIV-1 FP). Mixed isotherms of E1(64–81) and HIV-1 FP were obtained and their Brewster angle microscopy (BAM) and atomic force microscopy (AFM) images showed that the peptide mixture forms a different structure that is not present in the pure peptide images. Studies with lipid monolayers (1,2-dimyristoyl-sn-glycero-3-[phospho-rac-(1-glycerol)] (DMPG) and 1,2-dipalmitoyl-sn-glycero-3-phospho-rac-(1-glycerol) (DPPG)) show that both peptides interact with all the lipids assayed but the effect that HIV-1 FP has on the monolayers is reduced in the presence of E1(64–81). Moreover, differential scanning calorimetry (DSC) experiments show the capacity of HIV-1 FP to modify the properties of the bilayer structure and the capacity of E1(64–81) to inhibit these modifications. Our results indicate that E1(64–81) interacts with HIV-1 FP to form a new structure, and that this may be the cause of the previously observed inhibition of the activity of HIV-1 FP by E1(64–81)., This work was supported by project CTQ2006-15396-C02-02/01-BQU from the Secretaría de Estado de Investigación, Ministerio de Ciencia e Innovación, Dirección General de Programas y transferencia de conocimiento, Subdirección General de Proyectos de Investigación (Spain). M.J. Sánchez-Martín is a recipient of an FPI programme pre-doctoral grant. The authors are members of the consolidated research group recognized by the Generalitat de Catalunya “Peptides and Proteins: physicochemical studies” (2005SGR00278).