GSE118463
TFEB activation in macrophages attenuates postmyocardial infarction ventricular dysfunction independently of ATG5-mediated autophagy
Lysosomes are at the epicenter of cellular processes critical for inflammasome activation in macrophages, including autophagy and lipid metabolism. Inflammasome activation and IL1-beta secretion are implicated in atherogenesis, ischemic cardiac injury and resultant heart failure; however, little is known about the role of macrophage lysosome function in regulating these processes. We hypothesized that macrophages exhibit lysosome dysfunction in heart failure due to ischemic injury, and that augmentation of macrophage lysosomal biogenesis via macrophage-specific overexpression of transcription factor EB (mf-TFEB) would attenuate ischemic remodeling by modulating macrophage inflammatory responses. In both mice subject to ischemia-reperfusion injury, and human heart tissue from patients with ischemic cardiomyopathy, we find evidence of lysosome insufficiency and autophagic impairment, respectively. Mf-TFEB overexpression significantly attenuated post-IR adverse left ventricular remodeling at 4 weeks without affecting scar size. Mf-TFEB overexpression reduced the relative amounts of pro-inflammatory macrophage populations in the myocardium. RNA sequencing of flow-sorted cardiac macrophages post-IR confirmed that TFEB stimulated a lysosomal transcriptional program in macrophages, and upregulated key targets involved in lysosomal lipid metabolism, which we show are critical for inflammasome suppression. Both TFEB-dependent inflammasome suppression and effects on post-IR remodeling were independent of autophagy. Our findings suggest that TFEB reprograms macrophage lysosomal lipid metabolism to attenuate inflammasome activity and protect against post-ischemic cardiac remodeling and simultaneously shift our understanding of how autophagy and lipid metabolism impact acute inflammation.   Overall design: Macrophages were flow-sorted on the basis of CCR2 overexpression (CCR2pos and CCR2neg). Four TFEB-TG (TFEB expression cassette preceded by a floxed stop sequence) and five TFEB-wt (no expression cassette) cell samples, all lacking Cre (Cre-neg), were compared in order to evaluate mRNAs differentially expressed in response to the presence of the TFEB-TG cassette alone.  After eliminating these mRNAs, TFEB-TG and TFEB-wt samples expressing Cre (mac-TFEB and CX3CR1-Cre) were compared to detect mRNAs differentially expressed in response to TFEB overexpression.