The Inflammasome Signaling Pathway Is Actively Regulated and Related to Myocardial Damage in Coronary Thrombi from Patients with STEMI

Abstract

Background. The Nod-Like-Receptor-Protein-3 (NLRP3) inflammasome and the Interleukin-6 (IL-6) pathways are central mechanisms of the inflammatory response in myocardial reperfusion injury. Expanding our knowledge about the inflammasome signaling axis is important to improve treatment options. In a cross-sectional study, we aimed to study presence, localization, and genetic expression of inflammasome- and IL-6- signaling-related proteins in coronary thrombi and circulating leukocytes from ST-elevation myocardial infarction (STEMI) patients, with relation to myocardial injury and time from symptoms to PCI. Methods. Intracoronary thrombi were aspirated from 33 STEMI patients. Blood samples were drawn. mRNA of Toll-Like-Receptor-4 (TLR4), NLRP3, caspase 1, Interleukin-1β (IL1-β), Interleukin-18 (IL-18), IL-6, IL-6-receptor (IL-6R), and glycoprotein 130 (gp130) were isolated from thrombi and circulating leukocytes and relatively quantified by RT-PCR. A part of each thrombus was embedded in paraffin for histology and immunohistochemistry analyses. Results. Genes encoding the 8 markers were present in 76-100% of thrombi. Expression of TLR4 in thrombi significantly correlated to troponin T ( r = 0.455 , p = 0.013 ), as did NLRP3 ( r = 0.468 , p = 0.024 ). Troponin T correlated with expression in circulating leukocytes of TLR4 ( r = 0.438 , p = 0.011 ), NLRP3 ( r = 0.420 , p = 0.0149 ), and IL-1β ( r = 0.394 , p = 0.023 ). IL-6R expression in thrombi correlated significantly to troponin T ( r = 0.434 , p = 0.019 ), whereas gp130 was inversely correlated ( r = − 0.398 , p = 0.050 ). IL-6 in circulating leukocytes correlated inversely to troponin T ( r = − 0.421 , p = 0.015 ). There were no significant correlations between genes expressed in thrombi and time from symptom to PCI. Conclusions. The inflammasome signaling pathway was actively regulated in coronary thrombi and in circulating leukocytes from patients with STEMI, in association with myocardial damage measured by troponin T. This supports the strategy of medically targeting this pathway in treating myocardial infarction and contributes to sort out optimal timing and targets for anti-inflammatory treatment. The study is registered at clinicaltrials.gov with identification number NCT02746822.

TIMP-1 expression in coronary thrombi associate with myocardial injury in ST-elevation myocardial infarction patients

“…The thrombus aspiration in ST-elevation myocardial infarction (TASTI) study included 33 patients admitted to Oslo University Hospital Ullevål in the time period of August 2015 to January 2019. Inclusion and exclusion criteria have been described in detail previously [19]. Briefly, the main inclusion criterion was ST-elevation myocardial infarction (STEMI) treated with primary PCI and thrombus aspiration.…”

Circulating Microvesicles in Association with the NLRP3 Inflammasome in Coronary Thrombi from STEMI Patients

“…Among the aspirated thrombi, 30 were adequately analysed for gene expression, and as previously published, we found genes coding for the measured inflammasome-related variables to be present in 76–100% of the thrombi [ 22 ].…”

“…In addition, the use of heparin during the procedure may have influenced the results. The median ischaemic time was relatively short, and in the main study, no relationships between time from symptoms onset to PCI and the expression of inflammasome-related variables in the thrombi were detected either [ 22 ]. Somewhat inconsistent with our results, an inverse relationship between total and cell-specific AV + MVs and ischaemic time has been reported; however, only in non-STEMI and not in STEMI patients [ 35 ], suggesting that MVs expression during an acute MI is time-dependent [ 36 , 37 ].…”

“…Gene expression analyses. The details of the gene expression analyses have previously been described [ 22 ]. In brief, RNA was isolated from the thrombi using High Pure RNA Tissue Kit with the addition of Proteinase K Solution (Roche Diagnostics GmbH, Mannheim, Germany), stabilized by lysing buffer, and homogenized with a thermomixer (Thermomixer Eppendorf, Eppendorf AG, Hamburg, Germany) and stainless-steel grinding balls (Qiagen GmbH, Hilden, Germany).…”

“…We have previously shown inflammasome-related genes to be upregulated in coronary thrombi from STEMI patients [ 22 ]. Growing evidence indicates that inflammasome activity correlates with the enhanced secretion of EVs and the modulation of their protein cargo [ 23 , 24 ].…”