Fig. 7.

MCP-1 increases podocyte permeability to albumin. A: Evans blue-labeled albumin (EBA) can be quantified by the absorbance characteristics of the Evans blue dye, which absorbs light most strongly at 620 nm. In our tests, the A₆₂₀ measurement is oblivious to DMEM but is quite sensitive to the mixture of DMEM+EBA. B: in a Transwell setup to assay the cellular permeability to EBA, performed after the transepithelial electrical resistance had plateaued at 114.5 ± 24.6 Ω·cm², significantly more EBA had diffused from the lower into the upper chamber across the podocyte monolayer at 24 h as a result of MCP-1 treatment (50 ng/ml) vs. control. TGF-β (2 ng/ml) had a similar effect on EBA transit, although not statistically significant. The permeability to albumin induced by MCP-1 or TGF-β was returned to control levels by concurrent treatment with RS102895 (6 μM), an inhibitor of CCR2 signaling (n = 4). *P < 0.05 vs. control. †P < 0.05 vs. MCP-1. ‡P < 0.05 vs. TGF-β.