MD-1 Deficiency Accelerates Myocardial Inflammation and Apoptosis in Doxorubicin-Induced Cardiotoxicity by Activating the TLR4/MAPKs/Nuclear Factor kappa B (NF-κB) Signaling Pathway

Abstract

Background: Myocardial apoptosis and inflammation play important roles in doxorubicin (DOX)-caused cardiotoxicity. Our prior studies have characterized the effects of myeloid differentiation protein 1(MD-1) in pathological cardiac remodeling and myocardial ischemia/reperfusion (I/R) injury, but its participations and potential molecular mechanisms in DOX-caused cardiotoxicity remain unknown. Material/Methods: In the present study, MD-1 knockout mice were generated, and a single intraperitoneal injection of DOX (15 mg/kg) was performed to elicit DOX-induced cardiotoxicity. Cardiac function, histological change, mitochondrial structure, myocardial death, apoptosis, inflammation, and molecular alterations were measured systemically. Results: The results showed that the protein and mRNA levels of MD-1 were dramatically downregulated in DOX-treated cardiomyocytes. DOX insult markedly accelerated cardiac dysfunction and injury, followed by enhancements of apoptosis and inflammation, all of which were further aggravated in MD-1 knockout mice. Mechanistically, the TLR4/MAPKs/NF-kB pathways, which were over-activated in MD-1-deficient mice, were significantly increased in DOX-damaged cardiomyocytes. Moreover, the abolishment of TLR4 or NF-kB via a specific inhibitor exerted protective effects against the adverse effects of MD-1 loss on DOX-caused cardiotoxicity. Conclusions: Collectively, these findings suggest that MD-1 is a novel target for the treatment of DOX-induced cardiotoxicity.

Piperine protects against pyroptosis in myocardial ischaemia/reperfusion injury by regulating the miR‐383/RP105/AKT signalling pathway

“…Then, the specimens were embedded in paraffin after fixation was completed, and the samples were cut into 5‐μm‐thick sections on glass slides. Afterwards, haematoxylin and eosin (H&E) staining was performed, and light microscopy was used to observe heart morphology as previously described 26,29 . To detect the severity of MIRI, five fields of each section were randomly selected.…”

“…To detect the severity of MIRI, five fields of each section were randomly selected. It was then scored by two individuals blinded to all experiments as previously demonstrated in line with criteria 26,29 :0, no damage; 1, mild injury (interstitial oedema and focal necrosis); 2, moderate injury (cardiomyocyte swelling and necrosis); 3, severe injury (formation of necrotic contraction bands and inflammatory cell enrichments); and 4, highly severe injury (expanded necrosis of contraction bands, inflammatory cell infiltration and haemorrhage).…”

“…Moreover, the protein expression of NLRP3 was viewed by immunohistochemistry as described in prior study 29,30 . In detail, after the sections were deparaffinized and hydrated, the hydrogen dioxide was used to block endogenous peroxidase.…”

“…Haematoxylin was made to re‐stain nucleus. Average optical density (AOD = IOD/Area) was calculated to statistical analysis as previously demonstrated 29 …”

“…Ventricular tissues were collected to view mitochondrial structure by transmission electron microscopy (TEM) as previously described 29 . Dissected heart tissues (1‐2 mm‐wide blocks) were immersed in 4% glutaraldehyde overnight.…”