Table 2. In vitro studies of effect of α-synuclein on microglia.
α-syn, α-Synuclein; O, oligomeric; F, fibrils; PF, protofibrils; N, nitrated; CM, conditioned media; ROS, reactive oxygen species; KO, knockout; *DM, double mutant not occurring in humans; ** α-syn content in CSF is not addressed; in italics, markers included in the studies that did not show any change.
| Reference | α-Syn | Type/origin | Cell | Observations | Notes |
|---|---|---|---|---|---|
| Zhang et al., 2005 | WT | 7-days aged O-α-syn | 1. Rat mesencephalic neuro-glia | ↑ROS and PGE2 | These changes required phagocytocis of α-syn. Mediated by (but not only) NADPH oxidase |
| 2. Rat primary microglia | Activated microglia profile | ||||
| No change in TNF or nitrites | |||||
| Jin et al., 2007 | WT | 1. LB disease post mortem brain tissue | Prostaglandin E2 receptor subtype2 KO primary microglia | 1. Lack of EP2 ↑ α-syn clearance | |
| 2. 7-days aged O-α-syn | 2. O-α-syn induced p67 and p47 phox translocation | ||||
| P47 translocation is EP2 dependent | |||||
| Thomas et al., 2007 | Murine | Non-aggregated and aggregated (O,F and PF) N-α-syn 50–500 nM | Mouse primary microglia | ↑ROS production if α-syn aggregated. Inhibited by K+ or H+ channels blockers | ↑ ROS not due to debris presence or unspecific amyloid effect. |
| Zhang et al., 2007 | WT; A53T; A30P | Recombinant 250 nM | Rat midbrain neuroglia | DAergic toxicity in all three α-syn mediated by microglia production of superoxide and intracellular ROS. This is partially Mac-1 mediated and independent of phagocytosis | Mediated by (but not only) Phox |
| Su et al., 2008 | WT | Recombinant 10, 50 and 250 nM | Mouse primary microglia | ↑Activated Iba1+ cells↑TNF release↑mRNA TNF, COX2, IL-1β, IL6, NOX and iNOS↑ROS | This is attenuated in CD36 KO cultures and mediated by ERK1/2 phosphorylation |
| Su et al., 2009 | (*)DM- A30P–A53T | Recombinant 2.5, 5 and 10 nM | Mouse primary microglia | ↑Activated Iba1+ cells↑mRNA TNF, IL-1β, IL6, IL10, COX2, NOX2 and iNOS↑TNF and IL-1β | This is attenuated in CD36 KO cultures and mediated by ERK1/2 phosphorylation |
| Klegeris et al., 2008 | WT; A53T; A30P; E46K; Δ71–82 | Recombinant monomeric | 1. Human THP-1. | 1. ↑TNF release by A53T and IL-1β by A53T an A30P in naïve THP-1. CM from IFN-γ primed-THP-1 exposed to any α-syn induced SHSY5Y toxicity and ↑ TNF and IL-1β release | Analysis of phosphorylation in WT α-syn-primed THP-1 showed ERK1 and 2, p38 and JNK MAP kinases activation |
| 2. Human primary microglia | 2. CM from WT IFN-γ-primed-microglia induced toxicity SHSY5Y | ||||
| Park et al., 2008 | WT; A53T; A30P; E46K; Δ1-95; NAC | Aggregated (F) and monomeric | 1. BV2. | 1. All monomeric α-syn and Δ1-95↑phagocyt Aggregated α-syn ↓phagocyt and abolish monomeric induced phagocytosis. | ↑Phagocyt not mediated by CR3, α6β1 integrin or CD47. β and γ-syn did not ↑phagocytosis |
| 2. Rat primary microglia | 2 and 3. Monomeric α-syn ↑phagocyt | ||||
| 3. RAW 264.7 murine macrophage | |||||
| Reynolds et al., 2008a | Murine | Aggregated (O) unmodified and N-α-syn 100 nM | 1. Mouse primary microglia. | N-α-syn ↑ TNF, IL-6, MCP-1 and IFN-γ | GDNF and BDNF is also increase in microglia upon stimulation |
| 2. (1) co-culture with MES23.5 | Both unmodified and N-α-syn induced TH+ cell death in co-culture or using CM from (1) | Transcriptome analysis, please refer to the original article. | |||
| ↑ mRNA in microglia: TNF, CCl2, IL-6, IL-1β, NFkB1-2, Rela, Fos, Raf1, Card10 and Casp8 | |||||
| Reynolds et al., 2008b | Murine | Aggregated N-α-syn 100 nM | Mouse primary microglia | Complex response of microglia with both proinflammatory and putative neuroprotective profile | If unaggregated N-α-syn did not induce changes. |
| Lee et al., 2009 | WT; A53T; A30P; E46K | Recombinant monomeric 0.1, 1, 5 and 10 μM | 1. Macrophages RAW264.7 | 1. WT ↑TNF, COX2 and iNOS. All mutants ↑TNF | Same was true for β and γ-syn NAC sequence is not necessary for activation |
| 2. Human primary macrophages | 2. WT ↑TNF | ||||
| Wilms et al., 2009 | WT | Recombinant α-syn O and F 0.5, 5, 50 and 500 ng/ml | Rat primary microglia | O-α-syn most efficiently induced ameboid shape and ↑NF-κB, p38 and ERk1/2 MAP kinases and ↑nitrites production | |
| Kim et al., 2009 | WT; A53T; A30P | 1. Transient transfection | 1. BV2. | ↑CD44 expression and cleavage ↑Mt1-MMP expression by BV2 transfected and exogenous α-syn on BV2 and microglia | If transplanted in vivo α-syn pretreated BV2 migrates from striatum to SN in a 6-OHDA PD model |
| 2. Recombinant 100 nM | 2. Mouse primary microglia | A53T overexpression ↑BV2 migration | |||
| α-Syn overexpression in BV2 ↑ERK1/2 | |||||
| Roodveldt et al., 2010 | WT; A53T; A30P; E46K | Monomeric (0.2, 1 and 5 μg/ml) | 1. Mouse primary mixed glia2. Mouse primary microglia | ↑IL-6 Mixed all α-syn. Enrich. A30P and E46K↑IL-1β A30P and E46K↑IL-10 Mixed A30P;↓IL-10 Enrich Microg A53T↑IL-10, RANTES, MCP-1 and MIP-1α: A30P and E46K↑ MCP-1 and MIP-1α: Mixed WT↑ TNF and IFNγ Enrich A30P↑Phagocyt. WT and A53T; ↓Phagocyt. A30P and E46K | |
| Lee et al., 2010 | WT; A53T | 1. Monomeric 1, 5, 10μM. | Rat primary microglia | 1. ↑TNF, Nitrite, IL-1β and ROS; ↑NFkB and AP-1 DNA binding and MAPK phosphorylation | Inhibition of MMP-3, 8 or 9 suppresses pro-inflammatory α-syn effect |
| 2. CM SHSY5Y-expressing α-syn | 2. CM: ↑TNF, Nitrite, IL-1β and ROS | ||||
| Schiess et al., 2010 | WT | CSF from sporadic PD (**) | HTB15 human glioblastoma | ↓ growth rate↑ intracellular α-syn | Unclear whether the increase is due to of ↑ α-syn expression or ↑uptake of exogenous α-syn |
| Alvarez-Erviti et al., 2011 | WT; A53T | CM SHSY5Y-expressing α-syn | BV2 | CM Wt: N.Ch. | If MPP+ pre-treated SHSY5Y: CM WT: mRNA TNF and IL-1α; ↑TNF |
| CM A53T: mRNA Il-1β; ↑IL-1β | A53T: mRNA IL-1β; ↑IL-1β | ||||
| Recomb WT: mRNA TNF, mRNA IL-1α; ↑TNF | |||||
| Couch et al., 2011 | WT | Recombinant | BV2 | Translocation NF-κB p65 to nucleus | |
| ↑TNF release | |||||
| Beraud et al., 2011 | WT | 7-days aged O+F 50 nM | 1. BV2 | 1. ↑NO and TNF release and ↑mRNA IL-1β, Peroxiredoxine-1, Heme oxigenase-1, TLR2 and3 ↓mRNA TLR7 | Microglia is activated through a classical activation pathway. |
| 2. Mouse primary microglia | 2. ↑mRNA TLR2, 3, 1 and 7, MYD88, Iba1, NFkB, TNF and IL-1β; ↓mRNA TLR4, 6 and 9 and CD36 | ||||
| Stefanova et al., 2011 | WT | 1. Debris from U373 cells (human astrocytoma) transfected with α-syn | BV2 | TLR4-dependent phagocytosis | |
| 2. Recombinant | |||||
| Rojanathammanee et al., 2011 | WT; A53T; A30P | Transient transfection | BV2 | ↑COX2↓Phagocytosis and LAMP1↑TNF releaseA53T ↑nitrite and IL6 release | It did not change BV2 survival or lead to neuronal toxicity in co-culture |
| No change in cPLA2, PLD1-2 and COX1 |