Figure 2.

M-920 prevents inflammasome activation in addition to glomerular cell death. (A, B) Both caspase inhibitors (M-920 and CIX) decrease glomerular cell death in db/db mice as detected by the TUNEL assay. (A) Representative TUNEL-stained glomeruli (size bar: 20 µm Higher magnification (top) of glomeruli indicated by black dotted lines and TUNEL-positive cells indicated by black arrowheads. (C, D) Both M-920 and CIX decrease caspase-3/7 activity, as detected by the FLICA assay. However, only M-920, but not CIX, also reduces caspase-1 activity (C, E). (F) In db/db mice treated with M-920, but not in those treated with CIX, the cleaved forms of IL-1β and IL-18 and expression of Nlrp3 are reduced in renal cortex extracts. (G) Renal inflammasome inhibition in M-920-treated db/db mice is associated with lower plasma IL-1β levels. (B, D–G) Mean value±SEM of at least six mice in each group; (C) representative images of frozen sections incubated with FLICA probes – overviews (size bar: 20 µm) and higher (4×) magnification of glomeruli (glomeruli indicated by white dotted circles); (F) representative immunoblots; *P<0.05. cl-Casp1, cleaved caspase-1; cl-Casp3/7, cleaved caspase-3/7; cl-IL-1β, cleaved IL-1β; cl-IL-18, cleaved IL-18; DAPI, 4′,6-diamidino-2-phenylindole; db/m, nondiabetic control; GAPDH, glyceraldehyde-3-phosphate dehydrogenase; HPF, high-power field; ns, not significant; P-IL-1β, plasma-IL-1β.