0 mg/ml and 0.5 mg/ml (Fig. 2A and

B). Because coating was performed at a concentration of 1.0 mg/ml, the observed effects on phagocytosis were not caused by the binding of different amounts of Aβ-peptides to the PSPs. Of note, compared to the other Aβ-peptide variants, more Selleck KU 57788 Aβ(2–40) bound to the PSP at the lower coating concentrations of 0.1 mg/ml and 0.05 mg/ml. During the phagocytosis of Aβ-peptide-coated PSPs, the expression of several pro- and anti-inflammatory markers were examined by flow cytometry and ELISA. Coating of the PSPs with Aβ(1–42), Aβ (2–40), Aβ (2–42) and Aβ (3p–42) caused a 25–35% decrease in MSRI expression on the phagocytes compared to uncoated PSPs (p < 0.05). No significant effect was observed for Aβ(1–40) – or BSA-coated Selleck Sotrastaurin PSPs ( Fig. 3A). Additionally, no significant alteration of the IL1 receptors or of CD206 was observed after coating the particles with Aβ peptides ( Fig. 3B–D). The IL-10 and TNFα levels were measured in cell culture supernatants after 72 h of phagocytosis of the Aβ-coated PSPs (Fig. 3E and F). The measurements were well above the limit of detection (1.56 pg/ml), and the coefficient of variation

was below 25%. Compared to the phagocytosis of uncoated PSPs, the IL-10 levels were decreased by 20–30% only in monocytes treated with Aβ(x–42)−coated PSPs (p < 0.01). Neither Aβ(x–40)− nor BSA-coated PSPs changed the IL-10 expression in monocytes. The TNFα levels were only increased

acetylcholine by coating the particles with Aβ2–40. The reduced expression of MSRI and the lower secretion of IL-10 indicate an induction of a proinflammatory polarization of monocytes during phagocytosis of Aβ(x–42) coated PSP. To assess the effects of Aβ-peptides on the phagocytosis of in vitro-differentiated phagocytes, THP-1 macrophages were analyzed in the assay described above. In contrast to human monocytes, the phagocytosis activity of THP-1 macrophages was not increased after adding soluble Aβ-peptides to the cell culture medium ( Fig. 1C). Similar to freshly prepared monocytes, coating PSPs with all tested Aβ-peptides resulted in increased phagocytosis (p < 0.0001) ( Fig. 1D). Among the untruncated Aβ(1-x) peptides, Aβ(1–42) was more active than Aβ(1–40) in stimulating the phagocytosis of PSPs (p < 0.05). Coating PSPs with N-terminally truncated Aβ(2–40) and Aβ(2–42) resulted in higher MFI values when compared to Aβ(1–40)− and Aβ(1–42)-coated PSPs, respectively (p < 0.05). The strongest induction of phagocytosis was observed with Aβ(2–42); compared to uncoated PSPs, the MFI values increased by 150% (p < 0.0001). Interestingly, Aβ(3p–42) was less effective than Aβ(2–42) in THP-1 macrophages, which is in contrast to our observations in primary human monocytes. Fluorescent, AF488-labeled E.