*Appendix A.1. Generation of Mouse Monoclonal Antibody 8E10 and P1A5*

Hybridoma cell lines were generated by immunizing C57BL/6 mice with recombinant human apoA1 protein (Merck KGaA, Darmstadt, Germany). Mouse immunization and generation of hybridoma cell lines were outsourced to the Cell Engineering Corporation (Osaka, Japan). Hybridoma culture supernatants containing antibodies with the desired binding specificity for equal recognition of non-oxidized and oxidized HDL were screened by ELISA. In brief, 1 μg/mL of recombinant human apoA1 protein or apoB-depleted serum with an apoA1 concentration of 1 μg/mL, diluted in PBS, were immobilized on 96-well plates at 37 ◦C for 1 h. After washing the wells with PBS, PBS with or without hydrogen peroxide (H2O2), sodium nitrite, and diethylenetriaminepentaacetic acid (DTPA) solution (final concentrations of 1 mol/L, 200 μmol/L, and 100 μmol/L, respectively) were added to the wells and incubated at 37 ◦C for 1 h. The wells were washed with PBS and blocked with 2% BSA in PBS at 25 ◦C for 1 h. The plates were then incubated with hybridoma culture supernatant at 25 ◦C for 1 h, followed by the addition of horseradish peroxidase (HRP)-conjugated goat anti-mouse IgG (Dako, Glostrup, Denmark) at 25 ◦C for 30 min. The wells were washed with PBS five times, SuperSignal ELISA pico chemiluminescent substrate (Thermo Fisher Scientific, Inc., Waltham, MA, USA) was added to the wells, and the chemiluminescence signal was measured using an Infinite F200 Pro microplate reader (Tecan, Mannedorf, Switzerland). The mAb 8E10 and P1A5 were selected by screening for equal recognition of lipid-free (recombinant protein) and lipidated (apoB-depleted serum) apoA1 under native conditions, as well as after oxidation by exposure to H2O2/NO2 −. In order to obtain sufficient antibodies for this study, mAb 8E10 was purified from the ascites fluid of ICR nude mice by Protein A-Sepharose chromatography. Preparation of mouse ascites fluid and purification of mAb 8E10 and P1A5 were outsourced to Kitayama Labes (Nagano, Japan).

#### *Appendix A.2. Synthesis of Biotin-PEG7-Cholesterol*

Fifteen milligrams of 3β-Hydroxy-Δ5-cholenic Acid (Wako) were dissolved in 500 μL of N,N-dimethylformamide. Then, 7.7 mg of 1-Ethyl-3-(3-dimethylaminopropyl) carbodiimide, hydrochloride (Dojindo), 4.6 mg of N-hydroxysuccinimide (Merck KGaA, Darmstadt, Germany), 23.8 mg of Biotin-PEG7-amine (BroadPharm), and 8.4 μL of triethylamine (Wako) were added, and the resulting solution was stirred at room temperature for 2 h. Silica gel column chromatography (10% methanol in chloroform) yielded Biotin-PEG7 cholesterol as a clear solid (4% yield). LC-MS (*m/z*): 951.4 [M + H]+.
