Fig. 5: Soluble uric acid impairs phagocytosis and bacterial killing in human neutrophils.

a Schematic of experimental workflow including blood collection from healthy individuals, isolation of neutrophils via dextran-sedimentation, and subsequent neutrophil assays. Created in BioRender. Steiger, S. (2026). https://BioRender.com/vg41jpc. b–d Blood neutrophils from healthy individuals were isolated and incubated with or without sUA (10 mg/dL) for 30 min. The surface expression (MFI) of CXCR2 (b), CD62L and CXCR4 (c), and CD101 (d) in human neutrophils determined by flow cytometry. (b–d, n = 13, triplicates of 4 biological replicates for each group). e–g Healthy human neutrophils were treated with or without sUA followed by incubation with LPS (10 µg/mL) and fMLP (500 ng/mL) for 10 min. Cytoskeletal dynamics were determined via flow cytometry using the MFI of forward scatter (FSC-H) for quantifying cellular size (e) and the MFI of side scatter (SSC-H) (f) and intracellular CD66b (g) for quantifying granularity. (e–g, n = 8–13, duplicates or triplicates of 4 biological replicates for each group). h Fluorescence images of pHrodo^TM E. coli Bioparticles^TM uptake under hyperuricemic conditions compared to inhibition with cytochalasin D (CytD, 10 µM). 10x magnification, scale bar 20 µm. i Phagocytosis of pHrodo^TM E. coli Bioparticles^TM after neutrophils were treated with or without sUA plus CytD (n = 15, three technical replicates of 5 biological replicates for each group). j Blood neutrophils were treated with or without sUA prior to incubation with LPS for 30 min and E. coli, DPI, 4-ABAH, or CytD for 1 h. Histogram and the percentage (%) of phagocytosed E. coli BFP was determined by flow cytometry (n = 6–8, two or three technical replicates of 3 biological replicates for each group). k Neutrophil killing of E. coli was determined after neutrophils were incubated with or without sUA followed by incubation with LPS and co-culture with E. coli in log-phase growth at a MOI of 1/20 for 2 h. At each timepoint, the co-culture was plated onto agar plates and allowed for overnight growth. Colonies were counted and the [CFU]/uL was determined using a standard curve. E. coli only and neutrophils only were used as controls. Extracellular UA concentrations measured in the supernatants (l) and intracellular sUA determined in neutrophil lysates (m) using a UA assay kit (n = 4–5). (l, m, one technical replicate of 4–5 biological replicates for each group). n–q Blood neutrophils were isolated and incubated with or without sUA in the presence or absence of febuxostat (50 µM) and rasburicase (1 µg/mL). The surface expression (MFI) of CXCR2 (n), CD62L (o), CXCR4 (p), and CD101 (q) determined by flow cytometry (n = 3–5). (n–q, one technical replicate of 3–5 biological replicates for each group). r Phagocytosis of pHrodo^TM E. coli Bioparticles^TM after healthy human neutrophils were treated with or without sUA in the presence or absence of febuxostat (50 µM) and rasburicase (1 µg/mL) determined by flow cytometry (n = 5–6, douplicates of 2–3 biological replicates for each group). Data are mean ± SD. P values are determined by one-or two-way ANOVA. n.s., not significant. Source data for b–g and i–r are provided as a Source Data file.