Alterations of human CSF and serum-based mitophagy biomarkers in the continuum of Alzheimer disease

Figures & data

Figure 1. Changes in mitophagy biomarkers across AD continuum. Violin plots of ANCOVA analyzes (A–D) levels of mitophagy markers PINK1, BNIP3L, and TFEB in biomarker-defined individuals. (A) CSF PINK1 showed higher levels in AD dementia compared to MCI-AD and CU groups. (B) Serum PINK1 showed higher levels in AD dementia compared to MCI-AD group. (C) Serum BNIP3L showed higher levels in AD dementia compared to MCI-AD group. (D) Serum TFEB showed lower levels in AD dementia compared to MCI-AD and CU groups. Notes: Data were adjusted for sex and age. *** = p < .001, ** = p < .01, * = p < .05. Abbreviations: AD, Alzheimer disease; MCI, mild cognitive impairment; CSF, cerebrospinal fluid; CU, cognitively unimpaired.

Figure 2. Mitophagy biomarkers vs Alzheimer disease (AD) phenotype. *, ** and *** denote p < 0.05, p < 0.01 and p < 0.001, respectively. Partial Pearson correlation for AD biomarkers, ATN and brain structures was adjusted for age and sex or in the case of cognition, for age, sex, and education. Blue asterisks denote significance after Holm-Bonferroni correction for multiple comparisons. CSF, cerebrospinal fluid; “A”, amyloid; “T”, tau; “N”, neurodegeneration; +, abnormal; -, normal; Aβ42/42, amyloid beta 42 to 40 ratio; Aβ42, amyloid beta 42; p-MAPT/tau (181), phosphorylated MAPT/tau (181); t-MAPT/tau, total MAPT/tau; NEFL, neurofilament light chain; NRGN, neurogranin.

Figure 3. Correlation between mitophagy biomarkers in serum and CSF. Notes: Pearson correlation, *** = p < .001, ** = p < .01, * = p < .05. Abbreviations: CSF, cerebrospinal fluid.

Table 2. Mitophagy and AD biomarkers in CSF and serum.

	Memory Clinic Cohort				P-values
	All patients	AD Dementia	AD-MCI Patients	CU Controls	AD-MCI vs. ADDementia	AD MCIvs. CU	AD Dementiavs. CU
Mitophagy biomarkers	N = 200	N = 100	N = 100	N = 46
CSF PINK1 ng/mL	1.2 (0.2)	1.3 (0.2)	1.1 (0.2)	1.0 (0.3)	<0.001	0.09	<0.001
Serum PINK1, ng/mL	4.8 (10.7)	6.4 (13.3)	3.2 (6.8)	5.1 (10.1)	0.01	0.21	0.73
Serum BNIP3L, ng/mL	2.5 (1.8)	2.9 (2.1)	2.1 (1.2)	2.7 (2.2)	0.02	0.48	0.60
Serum TFEB, pg/mL	705.0 (361.8)	670.1 (368.6)	744.3 (351.9)	966.5 (1562.5)	0.03	0.90	0.04
AD biomarkers
CSF Aβ42/40	0.04 (0.02)	0.04 (0.01)	0.04 (0.02)	0.09 (0.02)	0.74	<0.001	<0.001
CSF Aβ42, pg/mL	486.5 (187.2)	493.0 (203.2)	480.0 (170.5)	1138.8 (474.7)	0.99	<0.001	<0.001
CSF t-MAPT/tau, pg/mL	618.8 (409.2)	667.3 (465.0)	570.9 (341.3)	225.5 (113.1)	0.17	<0.001	<0.001
CSF p-MAPT/tau (181), pg/mL	101.9 (65.7)	107.4 (69.6)	96.4 (61.5)	37.2 (17.6)	0.29	<0.001	<0.001
Serum NEFL pg/mL	35.342 (26.4)	38.7 (21.0)	35.8 (31.2)	14.0 (5.6)	0.10	<0.001	<0.001
CSF NEFL pg/mL	1293.0 (910.3)	1571.2 (979.8)	1304.2 (864.1)	666.1 (455.3)	0.04	<0.001	<0.001
CSF NRGN, pg/mL	253.7 (103.8)	267.3 (107.8)	253.8 (101.6)	188.2 (70.8)	0.77	0.03	0.01

Data are presented as N (%) and mean (SD) unless otherwise specified.

P values are comparisons using Tukey post hoc tests (one-way analysis of covariance was used to test the main between group differences), ^adata were log-tranformed.

Abbreviations: MCI, mild cognitive impairment; AD, Alzheimer’s disease; CU, cognitively unimpaired; CSF, cerebrospinal fluid; NEFL, neurofilament light chain; NRGN, neurogranin.

Table 1. Characteristic of study participants.

	Memory Clinic Cohort				P-values
	All patients	AD Dementia	AD-MCI Patients	CU Controls	AD-MCI vs. ADDementia	AD MCIvs. CU	AD Dementiavs. CU
Demographic characteristics	N = 200	N = 100	N = 100	N = 46
Age, years	71.4 (7.9)	70.3 (8.6)	72.5 (6.9)	63.9 (9.4)	0.16	<0.001	<0.001
Female, n (%)	121 (60.5)	64 (64.0)	57 (57.0)	30 (65.2)	0.31	0.11	0.39
Education, years	14.4 (3.0)	14.0 (2.9)	14.7 (3.1)	15.6 (2.9)	0.16	0.29	0.01
APOE ɛ4 positive, n (%)*	110 (55.0)	52 (52.0)	58 (58.0)	5 (10.9)	0.78	<0.001	<0.001
MMSE score	22.0 (4.8)	18.5 (4.2)	24.9 (3.0)	29.0 (1.3)	<0.001	<0.001	<0.001
GDS-15	3.3 (2.7)	3.6 (3.1)	3.0 (2.4)	2.2 (2.2)	0.43	0.29	0.04
BAI	8.8 (7.6)	9.11 (7.5)	8.6 (7.6)	9.3 (6.6)	0.91	0.92	0.99
Comorbidities**
Hypertension, n (%)	89 (44.5)	41 (41.0)	48 (48.0)	17 (36.9)	0.78	0.89	0.99
Hypercholesterolemia, n (%)	66 (33.0)	32 (32.0)	34 (34.0)	13 (28.2)	0.99	0.99	0.99
Ischemic heart disease, n (%)	12 (6.0)	6 (6.0)	6 (6.0)	0 (0)	0.99	0.31	0.28
Chronic obstructive pulmonary disease, n (%)	14 (7.0)	5 (5.0)	9 (9.0)	1 (2.2)	0.52	0.32	0.82
Thyroid disease, n (%)	37 (18.5)	16 (16.0)	21 (21.0)	10 (21.7)	0.83	0.80	0.52
Neuropsychological tests
DS–F^a	–	7.2 (2.2)	8.4 (2.0)	9.4 (2.4)	0.002	0.05	<0.001
DS–B^a	–	3.7 (1.7)	5.1 (1.7)	6.6 (1.7)	<0.001	<0.001	<0.001
TMT A^a	–	107.1 (56.0)	64.4 (32.3)	37.2 (13.1)	<0.001	0.002	<0.001
TMT B^a	–	272.3 (61.9)	198.8 (86.5)	103.6 (60.7)	<0.001	<0.001	<0.001
p–VF^a	–	25.1 (10.3)	37.2 (13.4)	47.4 (12.7)	<0.001	<0.001	<0.001
S–VF^a	–	11.6 (5.2)	16.5 (5–3)	27.2 (6.2)	<0.001	<0.001	<0.001
BNT^a	–	9.9 (5.0)	6.2 (4.5)	1.7 (1.7)	<0.001	<0.001	<0.001
CDT^a	–	9.4 (3.9)	13.0 (2.4)	15.5 (0.7)	<0.001	0.003	<0.001
ROCF–C^a	–	18.0 (10.5)	25.3 (6.6)	30.0 (3.3)	<0.001	0.007	<0.001
LM–IR^a	–	4.6 (3.4)	8.2 (4.2)	18.0 (4.4)	<0.001	<0.001	<0.001
LM–DR^a	–	1.6 (2.4)	3.7 (4.6)	15.8 (5.4)	0.005	<0.001	<0.001
Brain structures
Hippocampal volume (mm^3)	–	6625.1 (862.7)	6692.84 (847.5)	7753.0 (755.9)	0.91	<0.001	<0.001
Entorhinal cortical thickness (mm)	–	2.6 (0.4)	2.7 (0.3)	3.0 (0.4)	0.42	<0.001	<0.001
Parahippocampal cortical thickness (mm)	–	2.3 (0.3)	2.4 (0.2)	2.6 (0.2)	0.06	0.004	<0.001
Gray matter volume (mm^3)	–	540783.2 (44811.5)	559119.6 (52236.7)	594469.5 (31371.8)	0.12	0.002	<0.001
Ventricular volume (mm^3)	–	49033.5 (17036.1)	47526.6 (19204.2)	41637.7 (29888.3)	0.93	0.43	0.33

Data are presented as N (%) and mean (SD) unless otherwise specified.

P values are comparisons using Tukey post hoc tests (one-way analysis of variance was used to test the main between group differences).

Abbreviations: MCI, mild cognitive impairment; AD, Alzheimer disease; CU, cognitively unimpaired; APOE, apolipoprotein E; MMSE, Mini Mental State Examination; GDS-15, Geriatric Depression Scale, 15-item version; BAI, Beck Anxiety Inventory; DS-F, Digit Span Forward; DS-B, Digit Span Backward; TMT, Trail Making Test; p-VF, phonemic verbal fluency (letters N, K, P); S-VF, semantic verbal fluency (animals); BNT, Boston Naming Test (30 odd-items version), number of errors; CDT, Clock Drawing Test; ROCF-C, Rey-Osterrieth Complex Figure, copy condition; LM-IR, Logical Memory Story I, immediate recall; LM-DR, Logical Memory Story I, delayed recall.

*Missing genotype data in n = 35.

**Missing data in AD dementia (n = 5), AD MCI (n = 1), CU controls (n = 6).