Resuscitation-associated endotheliopathy (RAsE): a conceptual framework based on a systematic review and meta-analysis.

INTRODUCTION: Shock-induced endotheliopathy (SHINE), defined as a profound sympathoadrenal hyperactivation in shock states leading to endothelial activation, glycocalyx damage, and eventual compromise of end-organ perfusion, was first described in 2017. The aggressive resuscitation therapies utilised in treating shock states could potentially lead to further worsening endothelial activation and end-organ dysfunction. OBJECTIVE: This study aimed to systematically review the literature on resuscitation-associated and resuscitation-induced endotheliopathy. METHODS: A predetermined structured search of literature published over an 11-year and 6-month period (1 January 2011 to 31 July 2023) was performed in two indexed databases (PubMed/MEDLINE and Embase) per PRISMA guidelines. Inclusion was restricted to original studies published in English (or with English translation) reporting on endothelial dysfunction in critically ill human subjects undergoing resuscitation interventions. Reviews or studies conducted in animals were excluded. Qualitative synthesis of studies meeting the inclusion criteria was performed. Studies reporting comparable biomarkers of endothelial dysfunction post-resuscitation were included in the quantitative meta-analysis. RESULTS: Thirty-two studies met the inclusion criteria and were included in the final qualitative synthesis. Most of these studies (47%) reported on a combination of mediators released from endothelial cells and biomarkers of glycocalyx breakdown, while only 22% reported on microvascular flow changes. Only ten individual studies were included in the quantitative meta-analysis based on the comparability of the parameters assessed. Eight studies measured syndecan-1, with a heterogeneity index, I2 = 75.85% (pooled effect size, mean = 0.27; 95% CI - 0.07 to 0.60; p = 0.12). Thrombomodulin was measured in four comparable studies (I2 = 78.93%; mean = 0.41; 95% CI - 0.10 to 0.92; p = 0.12). Three studies measured E-selectin (I2 = 50.29%; mean = - 0.15; 95% CI - 0.64 to 0.33; p = 0.53), and only two were comparable for the microvascular flow index, MFI (I2 = 0%; mean = - 0.80; 95% CI - 1.35 to - 0.26; p < 0.01). CONCLUSION: Resuscitation-associated endotheliopathy (RAsE) refers to worsening endothelial dysfunction resulting from acute resuscitative therapies administered in shock states. In the included studies, syndecan-1 had the highest frequency of assessment in the post-resuscitation period, and changes in concentrations showed a statistically significant effect of the resuscitation. There are inadequate data available in this area, and further research and standardisation of the ideal assessment and panel of biomarkers are urgently needed.

Complex Effects of Putative DRP-1 Inhibitors on Stress Responses in Mouse Heart and Rat Cardiomyoblasts.

Dynamin-related protein-1 (DRP-1)-dependent mitochondrial fission may influence cardiac tolerance to ischemic or oxidative stress, presenting a potential "cardioprotective" target. Effects of dynamin inhibitors [mitochondrial division inhibitor 1 (MDIVI-1) and dynasore] on injury, mitochondrial function, and signaling proteins were assessed in distinct models: ischemia-reperfusion (I-R) in mouse hearts and oxidative stress in rat H9c2 cardiomyoblasts. Hearts exhibited substantial cell death [approx. 40 IU lactate dehydrogenase (LDH) efflux] and dysfunction (approx. 40 mmHg diastolic pressure, approx. 40% contractile recovery) following 25 minutes' ischemia. Pretreatment with 1 µM MDIVI-1 reduced dysfunction (30 mmHg diastolic pressure, approx. 55% recovery) and delayed without reducing overall cell death, whereas 5 µM MDIVI-1 reduced overall death at the same time paradoxically exaggerating dysfunction. Postischemic expression of mitochondrial DRP-1 and phospho-activation of ERK1/2 were reduced by MDIVI-1. Conversely, 1 µM dynasore worsened cell death and reduced nonmitochondrial DRP-1. Postischemic respiratory fluxes were unaltered by MDIVI-1, although a 50% fall in complex-I flux control ratio was reversed. In H9c2 myoblasts stressed with 400 µM H2O2, treatment with 50 µM MDIVI-1 preserved metabolic (MTT assay) and mitochondrial (basal respiration) function without influencing survival. This was associated with differential signaling responses, including reduced early versus increased late phospho-activation of ERK1/2, increased phospho-activation of protein kinase B (AKT), and differential changes in determinants of autophagy [reduced microtubule-associated protein 1 light chain 3b (LC3B-II/I) vs. increased Parkinson juvenile disease protein 2 (Parkin)] and apoptosis [reduced poly-(ADP-ribose) polymerase (PARP) cleavage vs. increased BCL2-associated X (BAX)/B-cell lymphoma 2 (BCL2)]. These data show MDIVI-1 (not dynasore) confers some benefit during I-R/oxidative stress. However, despite mitochondrial and metabolic preservation, MDIVI-1 exerts mixed effects on cell death versus dysfunction, potentially reflecting differential changes in survival kinase, autophagy, and apoptosis pathways. SIGNIFICANCE STATEMENT: Inhibition of mitochondrial fission is a novel approach to still elusive cardioprotection. Assessing effects of fission inhibitors on responses to ischemic or oxidative stress in hearts and cardiomyoblasts reveals mitochondrial division inhibitor 1 (MDIVI-1) and dynasore induce complex effects and limited cardioprotection. This includes differential impacts on death and dysfunction, survival kinases, and determinants of autophagy and apoptosis. Although highlighting the interconnectedness of fission and these key processes, results suggest MDIVI-1 and dynasore may be of limited value in the quest for effective cardioprotection.

Sustained ligand-activated preconditioning via δ-opioid receptors.

We have previously described novel cardioprotection in response to sustained morphine exposure, efficacious in young to aged myocardium and mechanistically distinct from conventional opioid or preconditioning (PC) responses. We further investigate opioid-dependent sustained ligand-activated preconditioning (SLP), assessing duration of protection, opioid receptor involvement, additivity with conventional responses, and signaling underlying preischemic induction of the phenotype. Male C57BL/6 mice were treated with morphine (75-mg subcutaneous pellet) for 5 days followed by morphine-free periods (0, 3, 5, or 7 days) before ex vivo assessment of myocardial tolerance to 25-min ischemia/45-min reperfusion. SLP substantially reduced infarction (by ∼50%) and postischemic contractile dysfunction (eliminating contracture, doubling force development). Cardioprotection persisted for 5 to 7 days after treatment. SLP was induced specifically by δ-receptor and not κ- or µ-opioid receptor agonism, was eliminated by δ-receptor and nonselective antagonism, and was additive with adenosinergic but not acute morphine- or PC-triggered protection. Cotreatment during preischemic morphine exposure with the phosphoinositide-3 kinase (PI3K) inhibitor wortmannin, but not the protein kinase A (PKA) inhibitor myristoylated PKI-(14-22)-amide, prevented induction of SLP. This was consistent with shifts in total and phospho-Akt during the induction period. In summary, data reveal that SLP triggers sustained protection from ischemia for up to 7 days after stimulus, is δ-opioid receptor mediated, is induced in a PI3K-dependent/PKA-independent manner, and augments adenosinergic protection. Mechanisms underlying SLP may be useful targets for manipulation of ischemic tolerance in young or aged myocardium.