Fig. 4

Intracellular urate accumulation is required for its anti-inflammatory effect in microglia. a BV2 cells and rat primary microglia seeded in a 6-well plate were cultured for 24 h; Glut9 and URAT1 levels were evaluated by Western blotting (n = 3). Protein extract from rat kidney tissue was probed as positive control. b BV2 cells were pretreated for 30 min with indicated concentrations of urate followed by LPS treatment for 24 h. Cell lysates were probed for URAT1 using indicated specific antibodies (left, n = 3). Protein band intensity was normalized to β-actin and is expressed as fold difference relative to the control group (right). c BV2 cells were pretreated with 1000 μM PBN and urate followed by LPS. Urate concentration in cell lysates was measured with a fluorometric assay kit (n = 6). d–f BV2 cells were pretreated with PBN and urate followed by LPS; NO (d, n = 4) and TNF-α (e, n = 4) levels in the culture supernatant were detected by ELISA. COX-2 expression was evaluated by Western blotting relative to the level of β-actin (f, left, n = 4). Protein band intensity was normalized to β-actin and is expressed as fold difference relative to the control group (f, right). g–i Rat primary microglia were pretreated with PBN and urate followed by LPS; NO (g, n = 4) and IL-1β (h, n = 3) levels in the culture supernatant were detected by ELISA. iNOS level was evaluated by Western blotting (i, left, n = 4) relative to that of β-actin and is expressed as fold difference relative to control group (i, right). Untreated cells served as the control (ctr). Data represent the mean ± SD. ^*p < 0.05, ^***p < 0.001 vs. control group; ^##p < 0.01, ^###p < 0.001 vs. LPS group; ^&p < 0.05, ^&&p < 0.01, ^&&&p < 0.001 vs. urate+LPS group (one-way analysis of variance)