Pervasive glycative stress links metabolic imbalance and muscle atrophy in early-onset Parkinson's disease

Abstract

Objective: Parkinson's disease (PD) is recognized as a systemic condition, with clinical features potentially modifiable by dietary intervention. Diets high in saturated fats and refined sugars significantly increase PD risk and exacerbate motor and non-motor symptoms, yet precise metabolic mechanisms are unclear. Our objective here was to investigate the interplay between diet and PD-associated phenotypes from a metabolic perspective.

Methods: We explored PARK7 KO mice under chronic glycative stress induced by prolonged high-fat high-sucrose (HFHS) diet. We investigated metabolic consequences by combining classical metabolic phenotyping (body composition, glucose tolerance, indirect calorimetry, functional assays of isolated mitochondria) with metabolomics profiling of biospecimens from mice and PD patients.

Results: We found this obesogenic diet drives loss of fat and muscle mass in early-onset PD mice, with a selective vulnerability of glycolytic myofibers. We show that PD mice and early-onset familial PD patients are under pervasive glycative stress with pathological accumulation of advanced glycation end products (AGEs), including N-α-glycerinylarginine (α-GR) and N-α-glycerinyllysine (α-GK), two previously unknown glycerinyl-AGE markers.

Conclusions: Our results offer the first proof for a direct link between diet, accumulation of AGEs and genetics of PD. We also expand the repertoire of clinically-relevant glycative stress biomarkers to potentially define at-risk patients before neurological or metabolic symptoms arise, and/or to monitor disease onset, progression, and effects of interventions.

Keywords: Advanced glycation endproducts (AGEs); Biomarkers; Glycative stress; Glycobiology; Muscle atrophy; Parkinson's disease.

Figure 1

HFHS diet drives resistance to body weight gain and muscle atrophy in early-onset PD. (A) Body weight of WT and KO mice after 12 weeks of HFHS diet. (A–E) Box and whiskers plots showing quantification of fat (B), lean (C), gastrocnemius (D) and soleus (E) mass from WT and KO mice under HFHS diet. Whiskers show min to max, boxes represent lower and higher quartiles, and middle line is median (n = 6–7/group). (F) Transverse sections of gastrocnemius from WT and KO mice under HFHS diet stained with anti-myosin antibodies specific for type 1/slow (blue), fast type 2A (green) and fast type 2B (red) myosin heavy chains. Fast type 2X fibers are unstained and appear black. (G) Total fiber size in WT and KO muscles under HFHS diet (mean ± SEM; n = 6–7/group). (H) Fiber size according to fiber type (mean ± SEM; n = 6–7/group). (I) Normalized Park7 mRNA expression in different mouse hindlimb myonuclei [15] (mean ± SEM; n = 4). CSA, cross sectional area; TPM, transcript per million. Data were analyzed using unpaired Student's t-test (A-E, G, I) or two-way ANOVA with Tukey's post hoc test (H); ∗∗∗∗p ≤ 0.0001, ∗∗∗p ≤ 0.001, ∗∗p ≤ 0.01, ∗p ≤ 0.05, n.s. not significant. (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)

Figure 2

Pervasive accumulation of AGEs in disease-relevant specimens from early-onset PD mice and patients. (A) Scheme of metabolomics experiments. Figure elements created with SMART (Servier Medical Art, http://smart.servier.com/) and BioRender.com, and licensed under a Creative Common Attribution 4.0 International License. (B) KEGG pathway enrichment of significant RP-UHPLC-MS/MS metabolites in gastrocnemius muscles. (C) Volcano plot comparing HILIC-MS/MS quantified metabolites in gastrocnemius from WT and KO mice under HFHS diet. (D) Chemical structures of new glycerinyl-AGEs. (e–g) Box and whiskers plots showing quantification of glycerinyl-AGEs in gastrocnemius (E), soleus (F) and plasma (G) from WT and KO mice. Whiskers show min to max, boxes represent lower and higher quartiles, and middle line is median (n = 5–9/group). Data were analyzed using nonparametric Wilcoxon signed-rank test (G); ∗∗p ≤ 0.01, ∗p ≤ 0.05. (H) Sequence analysis of fibroblast DNA from two PARK7-related patients and healthy controls. The female (PD 1) and male (PD 2) patients carry a 4bp insertion in exon 1 (red box) leading to a premature stop codon (TAA) and a 3bp loss in exon 7 (red arrow), respectively. (I) Western blot analysis of PARK7 protein levels in healthy controls, patient fibroblasts, and V5-tagged PARK7-overexpressing HEK293 cells. (J) Glycerinyl-AGEs in fibroblasts from control and PARK7-related PD patients cultured under low (1.0 g/L) or high (4.5 g/L) glucose (mean ± SD; n = 4). (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)