NLRP3 Gene Silencing Ameliorates Diabetic Cardiomyopathy in a Type 2 Diabetes Rat Model

Abstract

BackgroundNucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3) inflammasome is associated with metabolic disorder and cell death, which are important triggers in diabetic cardiomyopathy (DCM). We aimed to explore whether NLRP3 inflammasome activation contributes to DCM and the mechanism involved.MethodsType 2 diabetic rat model was induced by high fat diet and low dose streptozotocin. The characteristics of type 2 DCM were evaluated by metabolic tests, echocardiography and histopathology. Gene silencing therapy was used to investigate the role of NLRP3 in the pathogenesis of DCM. High glucose treated H9c2 cardiomyocytes were used to determine the mechanism by which NLRP3 modulated the DCM. The cell death in vitro was detected by TUNEL and EthD-III staining. TXNIP-siRNA and pharmacological inhibitors of ROS and NF-kB were used to explore the mechanism of NLRP3 inflammasome activation.ResultsDiabetic rats showed severe metabolic disorder, cardiac inflammation, cell death, disorganized ultrastructure, fibrosis and excessive activation of NLRP3, apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC), pro-caspase-1, activated caspase-1 and mature interleukin-1β (IL-1β). Evidence for pyroptosis was found in vivo, and the caspase-1 dependent pyroptosis was found in vitro. Silencing of NLRP3 in vivo did not attenuate systemic metabolic disturbances. However, NLRP3 gene silencing therapy ameliorated cardiac inflammation, pyroptosis, fibrosis and cardiac function. Silencing of NLRP3 in H9c2 cardiomyocytes suppressed pyroptosis under high glucose. ROS inhibition markedly decreased nuclear factor-kB (NF-kB) phosphorylation, thioredoxin interacting/inhibiting protein (TXNIP), NLRP3 inflammasome, and mature IL-1β in high glucose treated H9c2 cells. Inhibition of NF-kB reduced the activation of NLRP3 inflammasome. TXNIP-siRNA decreased the activation of caspase-1 and IL-1β.ConclusionNLRP3 inflammasome contributed to the development of DCM. NF-κB and TXNIP mediated the ROS-induced caspase-1 and IL-1β activation, which are the effectors of NLRP3 inflammasome. NLRP3 gene silencing may exert a protective effect on DCM.

Protection of SAL B with H9C2 cells

“…Increasing of inflammation cytokines induces functional problems such as diastolic and systolic dysfunctions in diabetic cardiomyopathy (Adeghate et al 2010). Moreover, a depression of cardiac contractile function also promotes inflammatory cytokines release (Luo et al 2014). Previous study has shown that Sal B inhibits inflammatory factors release in vascular endothelial cells and in glial cells (Zhou et al 2014).…”

The Mitochondria in Diabetic Heart Failure: From Pathogenesis to Therapeutic Promise

“…For these reasons, the NLRP3 inflammasome is an attractive target to mitigate the inflammatory response associated with mitochondrial damage and metabolic stress that occurs in diabetes. In support of this concept, there are preclinical data demonstrating a protective effect of inflammasome inhibition in several models of cardiac injury (16,66,67,103). Although these data are provocative, further translational investigation is needed.…”

“…It is now established that mitochondrial damage, particularly in the context of toll-like receptor activation with release of mitochondrial DNA and/or ROS, can activate the NLRP3 inflammasome, leading to the cleavage and release of IL-1b and IL-18 through a caspase 1-dependent mechanism (42,90,109). Emerging evidence suggests that the NLRP3 inflammasome is hyperactivated in diabetes and contributes to inflammatory damage in the heart and other tissues (56,66,68,100,101). Interestingly, excess FFA, hyperglycemia, and ischemic stress have been shown to promote inflammasome assembly by producing mitochondrial and/or lysosome damage (97,100,101).…”

Chronic Heart Failure and Inflammation

“…[122][123][124][125] Cardiac inflammation and leukocyte recruitment, as observed in the setting of diabetic cardiomyopathy, seems to be mediated in part through the NLRP3 inflammasome in a similar fashion to MI. 68,[126][127][128][129][130] It has been hypothesized that the mechanism of inflammasome activation in diabetic cardiomyopathy is dependent on the combination of oxidative stress and reactive oxygen species production, as a result of mitochondrial dysfunction. 131,132 Damaged mitochondria are removed from the cell in a process known as mitophagy, and if this system is overwhelmed or ineffective, increased reactive oxygen species ensues.…”