Table 3 Complement as a biomarker for neurodegenerative diseases
From: The good, the bad, and the opportunities of the complement system in neurodegenerative disease
| Â | AD | ALS | Stroke | Epilepsy | TBI | MS |
|---|---|---|---|---|---|---|
C1 | C1q elevated in plasma enriched for astrocyte-derived exosomes (ADE) early in AD [201] | Elevated in serum [82] | Â | Â | Â | C1q elevated in plasma ADE [202] |
C4 | Elevated in serum [82] | C4d elevated in plasma 24 hr after stroke [204] | C4 is elevated in patients with uncontrolled seizures vs controlled [205] | C4b chronically elevated in plasma ADE in mild TBI [206] | ||
C3 | C3d elevated in ADE [201] | C3 Elevated in serum [82]. C3a unchanged in plasma of ALS patients compared with age-matched controls [209] | C3a elevated in plasma 1-14 days after stroke and correlated with prognosis [82, 204, 210] | Properdin & C3 elevated, iC3b decreased in serum of patients with uncontrolled seizures vs controlled seizures [205, 211] | C3b chronically elevated in plasma ADE in mild TBI [206], C3a elevated in serum immediately after injury and remains chronically elevated [212] | C3b/iC3b elevated in plasma ADE [202], and in whole plasma [207]. Properdin elevated in CSF [208] |
C5 |  | C5a elevated in the plasma of ALS patients [209] |  | Serum C5a increases immediately after injury & continues to rise up to 10 days post injury [212] | C5/C5a elevated in plasma ADE [202] | |
C5b-9 | C9 is elevated in plasma [203]. C5b-9 elevated in ADE [201]. sC5b-9 decreased in patients with MCI who later develop AD [213] | Elevated in plasma of ALS patients [209] | Plasma sC5b-9 is elevated after stroke and increases throughout recovery, but is decreased in mild cases [82, 210, 214] | C5b-9 elevated in plasma of patients with focal and generalized seizures, clusterin reduced [205] | Elevated in plasma ADE in mild TBI cases for up to 12 years after injury [206, 212] | C9 levels reduced in plasma and CSF of MS patients [207] |
Inhibitory factors | FI decreased in patients with MCI who later develop AD [213, 215]. Clusterin is elevated [217], CD59, CD46, CR1, DAF decreased in ADE [201] | Â | Â | fH elevated in plasma of patients with focal and generalized seizures, clusterin decreased in patients with uncontrolled seizures vs controlled [205] | FI, CR1, CD59, C4BP decreased shortly after injury in plasma ADE [206, 212] | fH elevated in plasma ADE [202], C1inh and fH elevated in plasma and CSF [207, 208] |
Factor B | Elevated in ADE [201] | Â | Â | Â | Â | fB reduced in CSF and plasma [207] |