The role of inflammation in postresuscitation myocardial dysfunction

The Selective NLRP3-inflammasome inhibitor MCC950 Mitigates Post-resuscitation Myocardial Dysfunction and Improves Survival in a Rat Model of Cardiac Arrest and Resuscitation

PURPOSE

To investigate the effects of the selective NLRP3 inflammasome inhibitor MCC950 on post-resuscitation myocardial function and survival in a rat model of cardiopulmonary resuscitation (CPR).

METHODS

Thirty-six Sprague Dawley rats were randomized into three groups: (1) MCC950, (2) control, and (3) sham. Each group consisted of a 6 h non-survival subgroup (n = 6) and a 48 h survival subgroup (n = 6). Ventricular fibrillation (VF) was induced and untreated for 6 min. CPR was initiated and continued for 8 min. Resuscitation was attempted with a 4 J defibrillation. MCC950 (10 mg/kg) or vehicle was administered via intraperitoneal injection immediately after the return of spontaneous circulation (ROSC). Myocardial function and sublingual microcirculation were measured after ROSC in the non-survival subgroups. Plasma levels of interleukin Iβ (IL-1β) and cardiac troponin I (cTnI) were measured at baseline and 6 h in the non-survival subgroups. Heart tissue was harvested to measure the NLRP3 inflammasome constituents, including NLRP3, apoptosis-associated speck-like protein (ASC), Caspase-1, and IL-1β. Survival duration and neurologic deficit score (NDS) were recorded and evaluated among survival groups.

RESULTS

Post-resuscitation myocardial function and sublingual microcirculation were improved in MCC950 compared with control (p < 0.05). IL-1β and cTnI were decreased in MCC950 compared to control (p < 0.01). The MCC950 treated groups showed significantly reduced ASC, caspase-1, and IL-1β compared with the control group (p < 0.05). Survival at 48 h after ROSC was greater in MCC950 (p < 0.05) with improved NDS (p < 0.05).

CONCLUSION

Administration of MCC950 following ROSC mitigates post-resuscitation myocardial dysfunction and improves survival.

Combined Therapy With Polyethylene Glycol-20k and MCC950 Preserves Post-Resuscitated Myocardial Function in a Rat Model of Cardiac Arrest and Cardiopulmonary Resuscitation

Background To investigate the therapeutic potential of combined therapy with polyethylene glycol-20k (PEG-20k) and MCC950 on post-resuscitation myocardial function in a rat model of cardiac arrest. Methods and Results Thirty rats were randomized into 5 groups: Sham, Control, PEG-20k, MCC950, PEG-20k+ MCC950. Except for sham, animals were subjected to 6 minutes of ventricular fibrillation followed by 8 minutes cardiopulmonary resuscitation. Two milliliters PEG-20k was administered by intravenous injection coincident with the start of cardiopulmonary resuscitation; MCC950 (10 mg/kg), a highly selective NLRP3 inflammasome inhibitor, was delivered immediately after restoration of spontaneous circulation. Myocardial function, sublingual microcirculation, mitochondrial function, plasma cardiac troponin I, and interleukin-1β, expression of proteins in SIRT1 (sirtuin 1)/PGC-1α (peroxisome proliferator-activated receptor gamma coactivator 1-alpha) and NLRP3 (the NOD-like receptor family protein 3) inflammasome pathways were evaluated. Following cardiopulmonary resuscitation, myocardial function was compromised with a significantly decreased cardiac output, ejection fraction, and increased myocardial performance index, cardiac troponin I. Sublingual microcirculation was disturbed with impaired perfused vessel density and microvascular flow index. Cardiac arrest reduced mitochondrial routine respiration, Complex I-linked respiration, respiratory control rates and oxidative phosphorylation coupling efficiency. PEG-20k or MCC950 alone restored mitochondrial respiratory function, restituted sublingual microcirculation, and preserved myocardial function, whereas a combination of PEG-20k and MCC950 further improved these aspects. PEG-20k restored the expression of SIRT1 and PGC-1α, and blunted activation of NLRP3 inflammasomes. MCC950 suppressed expression of cleaved-caspase-1/pro-caspase-1, ASC (apoptosis-associated speck-like protein), GSDMD [gasdermin d], and interleukin-1β. Conclusions Combined therapy with PEG-20k and MCC950 is superior to either therapy alone for preserving post-resuscitated myocardial function, restituting sublingual microcirculation at restoration of spontaneous circulation at 6 hours. The responsible mechanisms involve upregulated expression of SIRT1/PGC1-α in tandem with inhibition of NLRP3 inflammasomes.