Toll-like receptors and myocardial contractile dysfunction

Role of toll-like receptor-mediated pyroptosis in sepsis-induced cardiomyopathy

Sepsis, a life-threatening dysregulated status of the host response to infection, can cause multiorgan dysfunction and mortality. Sepsis places a heavy burden on the cardiovascular system due to the pathological imbalance of hyperinflammation and immune suppression. Myocardial injury and cardiac dysfunction caused by the aberrant host responses to pathogens can lead to cardiomyopathy, one of the most critical complications of sepsis. However, many questions about the specific mechanisms and characteristics of this complication remain to be answered. The causes of sepsis-induced cardiac dysfunction include abnormal cardiac perfusion, myocardial inhibitory substances, autonomic dysfunction, mitochondrial dysfunction, and calcium homeostasis dysregulation. The fight between the host and pathogens acts as the trigger for sepsis-induced cardiomyopathy. Pyroptosis, a form of programmed cell death, plays a critical role in the progress of sepsis. Toll-like receptors (TLRs) act as pattern recognition receptors and participate in innate immune pathways that recognize damage-associated molecular patterns as well as pathogen-associated molecular patterns to mediate pyroptosis. Notably, pyroptosis is tightly associated with cardiac dysfunction in sepsis and septic shock. In line with these observations, induction of TLR-mediated pyroptosis may be a promising therapeutic approach to treat sepsis-induced cardiomyopathy. This review focuses on the potential roles of TLR-mediated pyroptosis in sepsis-induced cardiomyopathy, to shed light on this promising therapeutic approach, thus helping to prevent and control septic shock caused by cardiovascular disorders and improve the prognosis of sepsis patients.

Resveratrol attenuates inflammation in the rat heart subjected to ischemia-reperfusion: Role of the TLR4/NF-κB signaling pathway

It has been previously reported that Toll‑like receptor 4 (TLR4)/NF‑κB signaling mediates early inflammation during myocardial ischemia and reperfusion. It has additionally been suggested that resveratrol produces cardioprotective and anti‑inflammatory effects. The aim of the present study was to investigate whether resveratrol could modulate TLR4/NF‑κB signaling, reduce neutrophil accumulation and TNF‑α induction in an ischemia/reperfusion injured rat heart model. Rats were randomly exposed to a sham operation, myocardial ischemia and reperfusion (MI/R), MI/R + resveratrol or MI/R + resveratrol + L‑NAME. The data showed that following MI/R, the expression of myocardial TLR4 and NF‑κB increased significantly in the area of induced ischemia. As compared with MI/R, resveratrol significantly attenuated the expression of TLR4 and NF‑κB and reduced the levels of myeloperoxidase, serum and myocardial TNF‑α production, myocardial infarct size and myocardial apoptosis induced by MI/R. All the effects of resveratrol were abolished upon application of L‑NAME, a nitric oxide (NO) synthase inhibitor. These data provide evidence that resveratrol inhibits TLR4/NF‑κB signaling in the rat heart subjected to MI/R, and the anti‑inflammatory effect of resveratrol is associated with NO production.

Activation of toll-like receptors and inflammasome complexes in the diabetic cardiomyopathy-associated inflammation

Diabetic cardiomyopathy is defined as a ventricular dysfunction initiated by alterations in cardiac energy substrates in the absence of coronary artery disease and hypertension. Hyperglycemia, hyperlipidemia, and insulin resistance are major inducers of the chronic low-grade inflammatory state that characterizes the diabetic heart. Cardiac Toll-like receptors and inflammasome complexes may be key inducers for inflammation probably through NF-κB activation and ROS overproduction. However, metabolic dysregulated factors such as peroxisome proliferator-activated receptors and sirtuins may serve as therapeutic targets to control this response by mitigating both Toll-like receptors and inflammasome signaling.

Myocardial protection by interferon-γ late preconditioning during cardiopulmonary bypass‑associated myocardial ischemia-reperfusion in pigs

The impact of interferon-γ (IFN-γ) late preconditioning on myocardial ischemia-reperfusion injury during cardiopulmonary bypass (CPB) and the underlying mechanism were investigated. Using a porcine model of myocardial ischemia-reperfusion injury during CPB with a 60-min aorta cross-clamp, 20 pigs (15±0.5 kg) were treated randomly with either a 1-ml (20,000 IU/kg) IFN-γ injection (IFN-γ group; n=10) or saline solution (control group; n=10) 24 h prior to CPB. Heart rate, blood pressure, left ventricular end-systolic pressure (LVESP), left ventricular end-diastolic pressure (LVEDP), creatine kinase isoenzyme-MB (CK-MB), and cardiac troponin I (cTnI) were measured before CPB, before aortic clamping, and at post-reperfusion intervals of 10, 30, 60 and 120 min. Heat shock protein 70 (HSP70), Mn-superoxide dismutase (Mn-SOD) and inducible nitric oxide synthase (iNOS) were measured by immunohistochemical staining in pre-CPB myocardial tissues. Myocardial cell apoptosis TUNEL measurement was assessed in samples obtained 60 min following reperfusion. Both groups exhibited no statistical differences in age, weight, gender and preoperative cardiac function, and worsened left ventricular function, and hemodynamic index reductions, and significant cTnI and CK-MB leakage was observed 10 and 30 min after reperfusion. At 10, 30 and 60 min following reperfusion, ventricular function and leakage of the IFN-γ group were significantly improved, and expression of HSP70, iNOS and Mn-SOD increased and myocardial cell apoptosis decreased. IFN-γ late preconditioning exhibited preventative effects on myocardial tissues in pigs during CPB surgery, likely due to increased HSP70, Mn-SOD and iNOS expression.