Table 1.
Overview of changes and biomarker potential of complement proteins in the cerebrospinal fluid (CSF) of mild cognitive impairment (MCI) and Alzheimer’s disease (AD) patients compared to a control group.
| Cerebrospinal fluid | |||
|---|---|---|---|
| Protein | Comparison | Change | Ref. |
| C1s | AD vs HC | ↑ | (38) |
| C1q | AD vs HC | = | (39, 40) |
| ↑ | (38) | ||
| MCI vs HC | = | (40) | |
| NA | + correlation with tTau | (40) | |
| C3 | AD vs HC | ↑ | (39, 41–43) |
| + correlation with cognitive impairment (MMSE) in AD | (41, 42) | ||
| AD vs MCI | = | (44) | |
| ↑ | (45) | ||
| AD vs MCI vs HC | = - correlation with cognitive decline progression (ADAS-Cog) in MCI |
(46) | |
| + interaction between C3 levels and APOE E4 alleles on CSF amyloid and tau | (47) | ||
| AD vs MCI | ↑ | (45) | |
| C4 | AD vs HC | ↑ | (45) |
| AD vs MCI | (↑) | (45) | |
| Clusterin | AD vs HC | ↑ | (39, 48, 49) |
| AD vs MCI vs HC | = + correlation with Tau and pTau |
(50) | |
| NA | + correlation with Aβ-associated atrophy in non-demented elderly | (51) | |
| CR1 | AD/MCI-AD vs MCI/HC | ↑ | (45) |
| Factor H | AD vs HC | = | (39) |
| ↑ | (41) | ||
| + correlation with cognitive impairment (MMSE) in AD | (41) | ||
| AD vs MCI | = | (44) | |
| AD vs MCI vs HC | = - correlation with cognitive decline progression (ADAS-Cog) and lateral ventricular volume in MCI |
(46) | |
The characteristics of the patient groups that were compared are indicated in the ‘comparison’ column. The ‘change’ column indicates which level alteration was observed for the respective complement component. Symbols: ↑ significant increase, (↑) increased, unsignificant trend, = unchanged. Amyloid-beta (Aβ), Alzheimer’s disease (AD), Alzheimer's Disease Assessment Scale-Cognitive Subscale (ADAS-Cog), healthy control (HC), mild cognitive impairment (MCI), mini-mental state examination (MMSE), not applicable (NA), total tau (tTau).