Figure 7.

Macrophages contribute to UA crystal granuloma formation. Alb-creERT2;Glut9^lox/lox and Glut9^lox/lox control mice were injected intraperitoneally with tamoxifen. Both groups were fed either an acidogenic diet enriched with inosine or a standard chow diet with inosine for 14 and 32 days. (A and B) Flow cytometric analysis of whole kidneys from HU+CU mice. Gating strategy to identify macrophages (CD45⁺MHCII⁺CD11b⁺F4/80^hiCD11c^lo), proinflammatory M1-like macrophages (CD45⁺MHCII⁺F4/80^hiCD11b⁺CD11c^loCX3CR1⁺CD206⁻), alternatively activated M2-like macrophages (CD45⁺MHCII⁺F4/80^hiCD11b⁺CD11c^loCX3CR1⁺CD206⁺), neutrophils (CD45⁺MHCII⁻CD11b⁺Gr-1⁺), and cDCs (CD45⁺MHCII⁺F4/80^loCD11b^hiCD11c^hi) (A). Absolute numbers of leukocyte subsets from kidneys of HU+CU mice on day 32 (n=5 mice per group) (B). (C) Absolute numbers of M1- and M2-like macrophages from HU+CU mice on days 14 and 32 determined by flow cytometry (n=5 mice per group, two-way ANOVA). Data are mean±SD. *P<0.05; ***P<0.001. (D) F4/80 immunostaining of kidney sections illustrating the infiltration of F4/80⁺ cells in HU+CU mice (D), but not in HU−CU (D’) and healthy mice (D’’ and D’’’) on day 32. Magnification, ×25. (E–G) Immunostaining of kidneys from mice with HU+CU shows that UA crystal granulomas were positive for the immune cell marker CD45 (E) and F4/80 (F), but not for the M2-like macrophage marker CD163 (G) on day 32. Magnification, ×200. (H–J) Immunostaining of a nephrectomy specimen reveals numerous UA crystal granulomas positive for CD68⁺ macrophages (H) and HLA-DR+ proinflammatory M1-like macrophages (I), but not for CD163⁺ alternatively activated M2-like macrophages (J) (magnification, ×400). The patient was a 65-year-old man with a history of urothelial carcinoma, interstitial nephritis and vascular nephropathy, type 2 diabetes, ischemic cardiopathy and high BP, and serum creatinine 2 mg/dl.