IL-33 and ST2 comprise a critical biomechanically induced and cardioprotective signaling system
J. Clin. Invest. Shoji Sanada, et al. 117:1538 doi:10.1172/JCI30634 [
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Figure 1IL-33 is induced by mechanical strain in cardiac fibroblasts. (
A and
B) Quantitative analyses of gene expression of IL-33 by quantitative PCR (
A) and sST2 by Northern analysis (
B) in rat neonatal cardiomyocytes (white bars) and fibroblasts (black bars) are shown above with representative images from Northern analyses of cardiac fibroblast RNA. Cells were subjected to cyclic strain (8%, 1 Hz) for the indicated periods. Values are relative to β-tubulin expression and are expressed as percentage of control in cardiac fibroblasts. Data are from at least 3 sets of independent experiments. *
P < 0.05, **
P < 0.01 versus baseline. (
C) Coomassie stain showed that the recombinant mature rat and human IL-33 with N-terminal His tag (10 and 3 μg protein, respectively, was loaded) were of high purity. (
D) Pull-down assay of recombinant rat IL-33 with mouse ST2L-Fc protein. The recombinant protein exhibited specific binding to mouse ST2. (
E) Western analysis of cardiomyocytes and cardiac fibroblasts subjected to cyclic strain (each 10 μg protein sample from whole cell lysate) for the indicated periods. For reference, 0.1 ng of recombinant IL-33 was applied in the right lane. (
F) Representative immunofluorescence microscopy images of left ventricular samples 1 week after sham operation or TAC. Anti-vimentin (top panels) or anti–discoidin domain receptor–2 (DDR-2; bottom panels) antibody was used to detect fibroblasts (red) for dual staining with IL-33 (green). Pressure overload by TAC induced IL-33 expression, particularly in noncardiomyocyte interstitial cells. Scale bar: 10 μm.
