Kidney-specific Csf2 #knockdown. #In vivo knockdown of gene expression achieved by transfecting #siRNA using the in vivo #Magnetofection kit

A heart–brain–kidney network controls adaptation to cardiac stress through tissue macrophage activation

• Katsuhito Fujiu et al. Nature Medicine, 2017.

Abstract

Heart failure is a complex clinical syndrome characterized by insufficient cardiac function. In addition to abnormalities intrinsic to the heart, dysfunction of other organs and dysregulation of systemic factors greatly affect the development and consequences of heart failure. Here we show that the heart and kidneys function cooperatively in generating an adaptive response to cardiac pressure overload. In mice subjected to pressure overload in the heart, sympathetic nerve activation led to activation of renal collecting-duct (CD) epithelial cells. Cell–cell interactions among activated CD cells, tissue macrophages and endothelial cells within the kidney led to secretion of the cytokine CSF2, which in turn stimulated cardiac-resident Ly6Clo macrophages, which are essential for the myocardial adaptive response to pressure overload. The renal response to cardiac pressure overload was disrupted by renal sympathetic denervation, adrenergic b2-receptor blockade or CD-cell-specific deficiency of the transcription factor KLF5. Moreover, we identified amphiregulin as an essential cardioprotective mediator produced by cardiac Ly6Clo macrophages. Our results demonstrate a dynamic interplay between the heart, brain and kidneys that is necessary for adaptation to cardiac stress, and they highlight the homeostatic functions of tissue macrophages and the sympathetic nervous system.

Kidney-specific Csf2 knockdown. 

In vivo knockdown of Csf2 gene expression was achieved by transfecting siRNA using the in vivo Magnetofection kit (OZ Bioscience), according to the manufacturer’s instructions. In brief, 50 μg of synthesized siRNA targeting Csf2 (5′-CGGAUUUCAUAGACAGCCUUAUU-3′; 5′-UAAGGCUGUCUAUGAAAUCCGUU-3′) or its scrambled control (5′-GCCGAAACUAGAUCCAUUGTTUU-3′; 5′-AACAAUGGAUCUAGUUUCGGCUU-3′) were mixed with 200 μl of SilenceMag and incubated for 20 min at room temperature. During this incubation, 8-week-old male mice were anesthetized, and a single midline laparotomy was made to gain access to the kidneys. Cylinder magnets were then placed on both kidneys, after which the siRNA solution was injected into the tail vein and allowed to circulate for 20 min with the magnets in place. The next day, gene expression analysis or the TAC procedure was performed.