Aβ1 42

Lyophilized peptides of Aβ_1–42 and scrambled-Aβ_1–42 were obtained from Eurogentec and resuspended at 1 mg/ml in 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) (Sigma-Aldrich) to obtain a homogeneous aggregate-free preparation as previously described⁵⁹ . We gently removed HFIP from samples with nitrogen stream, and stocks were stored at −80 °C until they were ready to use. We prepared fresh monomers and oligomers for each experiment. Prior to beginning the aggregation experiment, an optimized amount of peptide (25 μg) was fully resuspended in HFIP at 1 mg/ml, sonicated for 30 minutes in a water bath sonicator, dried, and resuspended at a concentration of 0.5 mg/ml in 10 mM phosphate buffer (PB) pH 7.4. Peptide aliquots were then sonicated for 10 minutes in a water bath sonicator at room temperature and centrifuged at 14,000 rpm for 30 minutes. The monomer-containing supernatant was used for further oligomerization. To obtain oligomers, 150 mM NaCl (Sigma-Aldrich) was added to the monomeric samples and incubated at 37 °C for 6 days. All preparation steps were performed using ultratrace metal-free reagents and water (Sigma-Aldrich).

Aβ_1–42 was purchased from Eurogentec (AnaSpec, Fremont, CA, USA; AS-64129-1), and oligomeric amyloid was prepared as described in Dahlgren et al. [31 (link)]. Briefly, Aβ lyophilized with a hexafluoroisopropanol film was dissolved in dry dimethyl sulfoxide (Sigma-Aldrich Co., Seoul, Korea) to obtain a concentration of 1 mM and sonicated for 180 s. Ham’s F-12 (Invitrogen, Carlsbad, CA, USA) was then added to a final concentration of peptide 0.1 mM, and the samples were rotated on a rotary shaker at 4 °C for 7 days.

Compound MR-39 ((S)-3-(4-cyanophenyl)-N-[[1-(3-chloro-4-fluorophenyl)cyclopropyl]methyl]-2-[3-(4-fluorophenyl)ureido]propanamide) was prepared as described previously in Stama et al. (2017) [29 (link)]. The FPR2 antagonist WRW4 was purchased from Alomone Labs, Israel. Aβ_1-42 (Kaneka Eurogentec Inc, Belgium) was prepared according to the commonly accepted method described by Dahlgren et al. (2002) [30 (link)]. Briefly, Aβ_1-42 was dissolved in HFIP (hexafluoroisopropanol, Sigma-Aldrich, St. Louis, MO, USA). Next, HFIP was removed under vacuum, and the peptide film was stored at − 20 °C. For the aggregation studies, the peptide was initially resuspended in DMSO (Sigma-Aldrich, St. Louis, MO, USA). For oligomeric conditions, culture media was added, and the peptide was incubated at 4 °C for 24 h. For fibrillar conditions, 10 mM HCl was added, and the peptide was incubated for 24 h at 37 °C [30 (link), 31 (link)].