Fig 2: Diagnostic performance of the PBMC biomarker model. (A) ROC curves comparing the diagnostic accuracy of individual biomarkers (LAMP1 and OPTN) and their combination in distinguishing PD patients from controls. Additional details are provided in Table 4. (B) PBMCs were isolated from blood samples of PD patients and age-matched controls. The expression levels of ALP-associated proteins were quantified, and autophagic flux and lysosomal pH were assessed in PBMCs. Correlation analysis was performed among ALP-associated proteins, autophagic activity, and clinical data. The diagnostic accuracy of the PBMC biomarker model incorporating LAMP1 and OPTN was evaluated using ROC curve analysis.

Fig 3: Correlation analysis of ALP-associated features in PBMCs. (A) Spearman’s rank correlation matrix among ALP-associated proteins. (B-N) Scatter plots illustrating correlations between levels of ATG5 and ATP13A2 (B), BAG3 (C), LAMP1 (D), OPTN (E), p62 (F); ATP13A2 and BAG3 (G), p62 (H); BAG3 and LAMP1 (I), OPTN (J), p62 (K); LAMP1 and OPTN (L), p62 (M); and OPTN and p62 (N) in PBMCs. Gray and orange circles represent individual control and PD samples, respectively. Spearman's rank correlation coefficient (r) and P-values are shown for each correlation.

Fig 4: Expression profiles of AD- and ALP-associated proteins in AD patient fibroblasts. (a) Representative images of Coomassie brilliant blue-stained membranes showing equal protein loading across samples from control and AD patients. (b) Representative immunoblot images of α-Tubulin used as a loading control to verify equal protein loading in fibroblasts from control and AD patients. (c) Immunoblot analysis of AD- and ALP-associated proteins (APP, BACE1, BAG2, BAG3, Cathepsin D, EEA1, GRP78, LAMP2A, NBR1, OPTN, PSEN2, RAB7, TAX1BP1, TFE3, TOLLIP, and Ubiquitin) in fibroblasts from control (n = 9) and AD patients (n = 9). (d,e) Quantification of BACE1 (d) and TAX1BP1 (e) protein levels. Statistical significance was determined using Mann–Whitney U test (p < 0.05). Violin plots show the distribution; overlaid dots represent individual subject-derived fibroblast lines (biological replicates). The central line indicates the median and the bounds of the box indicate the interquartile range (IQR).

Fig 5: Diagnostic performance of fibroblast biomarker models. (a) ROC curves assessing the diagnostic performance of individual proteins (BACE1, TAX1BP1, and BAG2) for discriminating AD patients from controls. (b) ROC curves showing protein combinations (BAG2 + OPTN and BACE1 + TFE3). (c) ROC curves for combinations of APOE4 status with individual protein markers or autophagic flux. Area under curve (AUC), sensitivity, specificity and other statistical parameters are detailed in Table 3. Note: Performance estimates may be optimistic due to small sample size and lack of independent validation.