Inhibition of serum podocyte toxicity by blockade of TNFα signaling.

(A) Upper panels—images of podocytes treated with 10% serum from a patient with podocyte toxic activity: FACs were immunostained with anti-vinculin antibody (green), actin was visualized with phalloidin (red) and nuclei were stained with DAPI. Lower panels: Images of podocytes pre-incubated with blocking antibodies against TNFα Receptor I and II (RI/II) prior to addition of the FSGS serum sample used in the images of the upper panel; scale bar 5 μm. (B) Effect of TNFα blockade on FAC numbers in podocytes exposed to toxic sera (N = 48). Means and standard errors are shown. (C) Percentages of patient serum samples with “strong” response (≥75% increase in the FAC number upon TNFα blockade vs no blockade for each sample tested), “weak” response (50% increase in the FAC numbers upon TNFα blockade vs no blockade for each sample tested) and “no response”.