Ischemic Post-Conditioning in a Rat Model of Asphyxial Cardiac Arrest.

BACKGROUND: Ischemic post-conditioning (IPoC) has been shown to improve outcomes in limited pre-clinical models. As down-time is often unknown, this technique needs to be investigated over a range of scenarios. As this tool limits reperfusion injury, there may be limited benefit or even harm after short arrest and limited ischemia-reperfusion injury. METHODS: Eighteen male Wistar rats underwent 7 min of asphyxial arrest. Animals randomized to IPoC received a 20 s pause followed by 20 s of compressions, repeated four times, initiated 40 s into cardiopulmonary resuscitation. If return of spontaneous circulation (ROSC) was achieved, epinephrine was titrated to mean arterial pressure (MAP) of 70 mmHg. Data were analyzed using t-test or Mann-Whitney test. Significance set at p ≤ 0.05. RESULTS: The rate of ROSC was equivalent in both groups, 88%. There was no statistically significant difference in time to ROSC, epinephrine required post ROSC, carotid flow, or peak lactate at any timepoint. There was a significantly elevated MAP with IPoC, 90.7 mmHg (SD 13.9), as compared to standard CPR, 76.7 mmHg (8.5), 2 h after ROSC, p = 0.03. CONCLUSIONS: IPoC demonstrated no harm in a model of short arrest using a new arrest etiology for CPR based IPoC intervention in a rat model.

Enhanced effect of limb remote ischemic postconditioning combined with paeoniflorin on alleviating cerebral ischemic injury via neutrophil NADPH pathway.

BACKGROUND: Limb remote ischemic postconditioning (LRIP) and paeoniflorin (PF) both can ameliorate cerebral ischemia reperfusion (I/R) injury. At present, whether LRIP combined with PF can achieve better therapeutic effect is unknown. PURPOSE: This study explored the alleviating effect and mechanism of LRIP in combination with PF on cerebral I/R injury in rats. METHODS: Middle cerebral artery occlusion (MCAO) surgery was performed on rats except Sham group. Then PF (2.5 mg/kg, 5 mg/kg, 10 mg/kg) was administrated by intraperitoneal injection 10 min before the start of reperfusion. LRIP was operated on the left femoral artery at 0 h of reperfusion. Behavioral testing was used to assess neurological impairment, while TTC staining was used to examine infarct volume. Protein expression of MyD88, TRAF6, p38-MAPK and phosphorylation of p47phox in neutrophils from rat peripheral blood were tested by Western blot. Rat bone marrow neutrophils were extracted and incubated for 24 h with serum from rats after LRIP combined with PF. p38 MAPK inhibitor group was administrated SB203580 while the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase inhibitor group was administrated Apocynin. Neutrophils were stimulated by fMLP (10 µM). Reactive oxygen species (ROS) production and protein expression of MyD88, TRAF6, p38 MAPK, and p47phox (ser 304 and ser 345) were detected. RESULTS: LRIP combined with PF (5 mg/kg) reduced cerebral infarct volume, ameliorated neurological deficit score (NDS), decreased fMLP-stimulated ROS release and downregulated the protein expression of MyD88, TRAF6, p38-MAPK and phosphorylation of p47phox (ser 304 and ser 345) in neutrophils. CONCLUSION: The protective effect of LRIP combined with PF on cerebral I/R injury was better than either alone. Taken together, we provided solid evidence to demonstrate that the combination of LRIP and PF had potential to alleviate cerebral I/R injury, which was regulated by MyD88-TRAF6-p38 MAPK pathway and neutrophil NADPH oxidase pathway.

Sevoflurane postconditioning ameliorates cerebral hypoxia/reoxygenation injury in zebrafish involving the Akt/GSK-3ß pathway activation and the microtubule-associated protein 2 promotion.

Sevoflurane postconditioning has been shown to provide neuroprotection against cerebral hypoxia-ischemia injury, but the mechanisms remain elusive. Microtubule-associated protein 2 (MAP2) is implicated in early neuronal hypoxia-ischemia injury. This study aimed to investigate whether the neuroprotective effects of sevoflurane postconditioning are related to the Akt/GSK-3ß pathway and its downstream target MAP2 in zebrafish hypoxia/reoxygenation (H/R) model. Sevoflurane postconditioning or GSK-3ß inhibitor TDZD-8 were used to treat H/R zebrafish. The cerebral infarction, neuronal apoptosis, and mitochondrial changes were evaluated using TTC staining, TUNEL staining, and transmission electron microscopy, respectively. The distribution of MAP2 in the brain was determined by immunofluorescence imaging. The levels of Akt, p-Akt, GSK-3ß, p-GSK-3ß, and MAP2 proteins were evaluated by Western blotting. The neurobehavioral recovery of zebrafish was assessed based on optokinetic response behavior. Our results indicated that sevoflurane postconditioning and TDZD-8 significantly reduced the cerebral infarction area, suppressed cell apoptosis, and improved mitochondrial integrity in zebrafish subjected to H/R. Furthermore, sevoflurane postconditioning and TDZD-8 elevated the ratios of p-Akt/Akt and p-GSK-3ß/GSK-3ß. However, the neuroprotective effect of sevoflurane postconditioning was effectively abolished upon suppression of MAP2 expression. In conclusion, sevoflurane postconditioning ameliorated cerebral H/R injury and facilitated the restoration of neurobehavioral function through the activation of Akt/GSK-3ß pathway and promotion of MAP2 expression.

Sevoflurane postconditioning attenuates cardiomyocytes hypoxia/reoxygenation injury via PI3K/AKT pathway mediated HIF-1α to regulate the mitochondrial dynamic balance.

BACKGROUND: Myocardial ischemia-reperfusion injury (I/RI) is a major cause of perioperative cardiac-related adverse events and death. Studies have shown that sevoflurane postconditioning (SpostC), which attenuates I/R injury and exerts cardioprotective effects, regulates mitochondrial dynamic balance via HIF-1α, but the exact mechanism is unknown. This study investigates whether the PI3K/AKT pathway in SpostC regulates mitochondrial dynamic balance by mediating HIF-1α, thereby exerting myocardial protective effects. METHODS: The H9C2 cardiomyocytes were cultured to establish the hypoxia-reoxygenation (H/R) model and randomly divided into 4 groups: Control group, H/R group, sevoflurane postconditioning (H/R + SpostC) group and PI3K/AKT blocker (H/R + SpostC + LY) group. Cell survival rate was determined by CCK-8; Apoptosis rate was determined by flow cytometry; mitochondrial membrane potential was evaluated by Mito Tracker™ Red; mRNA expression levels of AKT, HIF-1α, Opa1and Drp1 were detected by quantitative real-time polymerase chain reaction (qRT-PCR); Western Blot assay was used to detect the protein expression levels of AKT, phosphorylated AKT (p-AKT), HIF-1α, Opa1 and Drp1. RESULTS: Compared with the H/R group, the survival rate of cardiomyocytes in the H/R + SpostC group increased, the apoptosis rate decreased and the mitochondrial membrane potential increased. qRT-PCR showed that the mRNA expression of HIF-1α and Opa1 were higher in the H/R + SpostC group compared with the H/R group, whereas the transcription level of Drp1 was lower in the H/R + SpostC group. In the H/R + SpostC + LY group, the mRNA expression of HIF-1α was lower than the H/R + SpostC group. There was no difference in the expression of Opa1 mRNA between the H/R group and the H/R + SpostC + LY group. WB assay results showed that compared with the H/R group, the protein expression levels of HIF-1α, Opa1, P-AKT were increased and Drp1 protein expression levels were decreased in the H/R + SpostC group. HIF-1α, P-AKT protein expression levels were decreased in the H/R + SpostC + LY group compared to the H/R + SpostC group. CONCLUSION: SpostC mediates HIF-1α-regulated mitochondrial fission and fusion-related protein expression to maintain mitochondrial dynamic balance by activating the PI3K/AKT pathway and increasing AKT phosphorylation, thereby attenuating myocardial I/R injury.

DJ-1 preserves ischemic postconditioning-induced cardioprotection in STZ-induced type 1 diabetic rats: role of PTEN and DJ-1 subcellular translocation.

BACKGROUND: Ischemic postconditioning (IPostC) has been reported as a promising method for protecting against myocardial ischemia-reperfusion (MI/R) injury. Our previous study found that the infarct-limiting effect of IPostC is abolished in the heart of diabetes whose cardiac expression of DJ-1 (also called PARK7, Parkinsonism associated deglycase) is reduced. However, the role and in particular the underlying mechanism of DJ-1 in the loss of sensitivity to IPostC-induced cardioprotection in diabetic hearts remains unclear. METHODS: Streptozotocin-induced type 1 diabetic rats were subjected to MI/R injury by occluding the left anterior descending artery (LAD) and followed by reperfusion. IPostC was induced by three cycles of 10s of reperfusion and ischemia at the onset of reperfusion. AAV9-CMV-DJ-1, AAV9-CMV-C106S-DJ-1 or AAV9-DJ-1 siRNA were injected via tail vein to either over-express or knock-down DJ-1 three weeks before inducing MI/R. RESULTS: Diabetic rats subjected to MI/R exhibited larger infarct area, more severe oxidative injury concomitant with significantly reduced cardiac DJ-1 expression and increased PTEN expression as compared to non-diabetic rats. AAV9-mediated cardiac DJ-1 overexpression, but not the cardiac overexpression of DJ-1 mutant C106S, restored IPostC-induced cardioprotection and this effect was accompanied by increased cytoplasmic DJ-1 translocation toward nuclear and mitochondrial, reduced PTEN expression, and increased Nrf-2/HO-1 transcription. Our further study showed that AAV9-mediated targeted DJ-1 gene knockdown aggravated MI/R injury in diabetic hearts, and this exacerbation of MI/R injury was partially reversed by IPostC in the presence of PTEN inhibition or Nrf-2 activation. CONCLUSIONS: These findings suggest that DJ-1 preserves the cardioprotective effect of IPostC against MI/R injury in diabetic rats through nuclear and mitochondrial DJ-1 translocation and that inhibition of cardiac PTEN and activation of Nrf-2/HO-1 may represent the major downstream mechanisms whereby DJ-1 preserves the cardioprotective effect of IPostC in diabetes.

Impact of remote ischemic postconditioning on acute ischemic stroke in China: a systematic review and meta-analysis of randomized controlled trials.

OBJECTIVE: Acute ischemic stroke (AIS) is a significant health burden in China, affecting a sizable portion of the population. Conventional pharmacological treatments frequently fall short of desirable outcomes. Therefore, exploring alternative therapies is crucial. Remote ischemic postconditioning (RIPostC) is a noninvasive and cost-effective adjunctive therapy. This study aimed to investigate the efficacy and safety of RIPostC as an adjunctive therapy for AIS to inform clinical practice. METHODS: A comprehensive search was conducted across the PubMed, Embase, Web of Science, China National Knowledge Infrastructure (CNKI), WanFang, Weipu (VIP), and China Biology Medicine disc (CBM) databases up to October 2023. All included studies underwent bias risk assessment using the Cochrane risk-of-bias assessment tool. The primary outcome measure was the National Institute of Health Stroke Scale (NIHSS), with secondary outcomes including the Barthel index (BI), D-dimer, C-reactive protein (CRP), fibrinogen (FIB), brain-derived neurotrophic factor (BDNF), modified Rankin scale (mRS), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) levels. The data were analyzed using fixed-effects and random-effects models in Review Manager, with mean differences (MDs) and 95% confidence intervals (CIs) calculated for each outcome. The grading of recommendations, assessment, development, and evaluations (GRADE) approach was used to evaluate the level of evidence for each outcome measure. RESULTS: This meta-analysis included 38 studies, encompassing 4334 patients. Compared with the control group, the RIPostC group had significantly lower NIHSS scores, serum CRP, D-dimer, IL-6, TNF-α, and FIB levels, and increased BDNF levels. Moreover, it improved the patient's BI and mRS scores. According to the GRADE approach, the quality of evidence for mRS was deemed "moderate," while the NIHSS, BI, and CRP were rated as "low" quality. IL-6, TNF-α, FIB, D-dimer, and BDNF received "very low" quality ratings. CONCLUSION: The findings suggest that RIPostC activates endogenous protective mechanisms, providing benefits to patients with AIS.

Potential Effects of Ischemic Postconditioning and Changes in Heat Shock Protein 72 in Patients with Acute Myocardial Infarction without Prodromal Angina.

The effectiveness of ischemic postconditioning (iPoC) in patients with ST-elevation myocardial infarction (STEMI) without ischemic preconditioning has not been determined. Therefore, we investigated the impact of iPoC and its potential mechanism related to heat shock protein 72 (HSP72) induction on myocardial salvage in patients with STEMI without prodromal angina (PA).We retrospectively analyzed data from 102 patients with STEMI with successful reperfusion among 323 consecutive patients with acute coronary syndrome. Among these, 55 patients with iPoC (iPoC (+) ) underwent 4 cycles of 60-second inflation and 30-second deflation of the angioplasty balloon. Both the iPoC (+) and iPoC (-) groups were divided into 2 further subgroups: patients with PA (PA (+) ) and those without (PA (-) ). We analyzed HSP72 levels in neutrophils, which were measured until 48 hours after reperfusion. I-123 ß-methyl-p-iodophenyl-pentadecanoic acid (BMIPP) scintigraphy was performed within a week of reperfusion therapy. In 64% of patients, thallium-201 (TL) scintigraphy was performed 6-8 months after STEMI onset.Using BMIPP and TL, in the PA (-) subgroups, the iPoC (+) group had a significantly greater myocardial salvage ratio than the iPoC (-) group. iPoC was identified as an independent predictor of the myocardial salvage ratio. The HSP72 increase ratio was significantly elevated in the iPoC (+) PA (-) group. Importantly, the myocardial salvage effect in patients without PA was significantly correlated with the HSP72 increase ratio, which was greater in patients with iPoC.These results suggest the potential impact of iPoC via HSP72 induction on myocardial salvage; however, the effects may be limited to patients with STEMI without PA.

Mitochondrial Calcium Uniporter (MCU) is Involved in an Ischemic Postconditioning Effect Against Ischemic Reperfusion Brain Injury in Mice.

The phenomenon of ischemic postconditioning (PostC) is known to be neuroprotective against ischemic reperfusion (I/R) injury. One of the key processes in PostC is the opening of the mitochondrial ATP-dependent potassium (mito-KATP) channel and depolarization of the mitochondrial membrane, triggering the release of calcium ions from mitochondria through low-conductance opening of the mitochondrial permeability transition pore. Mitochondrial calcium uniporter (MCU) is known as a highly sensitive transporter for the uptake of Ca2+ present on the inner mitochondrial membrane. The MCU has attracted attention as a new target for treatment in diseases, such as neurodegenerative diseases, cancer, and ischemic stroke. We considered that the MCU may be involved in PostC and trigger its mechanisms. This research used the whole-cell patch-clamp technique on hippocampal CA1 pyramidal cells from C57BL mice and measured changes in spontaneous excitatory post-synaptic currents (sEPSCs), intracellular Ca2+ concentration, mitochondrial membrane potential, and N-methyl-D-aspartate receptor (NMDAR) currents under inhibition of MCU by ruthenium red 265 (Ru265) in PostC. Inhibition of MCU increased the occurrence of sEPSCs (p = 0.014), NMDAR currents (p < 0.001), intracellular Ca2+ concentration (p < 0.001), and dead cells (p < 0.001) significantly after reperfusion, reflecting removal of the neuroprotective effects in PostC. Moreover, mitochondrial depolarization in PostC with Ru265 was weakened, compared to PostC (p = 0.004). These results suggest that MCU affects mitochondrial depolarization in PostC to suppress NMDAR over-activation and prevent elevation of intracellular Ca2+ concentrations against I/R injury.

Remote Ischemic Postconditioning-Mediated Neuroprotection against Stroke by Promoting Ketone Body-Induced Ferroptosis Inhibition.

Neuronal death resulting from ischemic stroke is the primary cause of adult mortality and disability, and effective neuroprotective agents for poststroke intervention are still lacking. Remote ischemic postconditioning (RIPostC) has demonstrated significant protective effects against ischemia in various organs; however, the specific mechanisms are not fully understood. This study investigated the potential neuroprotective mechanisms of RIPostC in the context of ischemic stroke. Using a rat model of middle cerebral artery occlusion, we found that RIPostC mitigated neurological damage, improved movement in the open-field test, and protected against neuronal apoptosis. In terms of energy metabolism, RIPostC enhanced ATP levels, suppressed lactate content, and increased the production of ketone bodies (KBs). In the ferroptosis assay, RIPostC protected against lipoperoxidation, reversed the reduction of glutathione peroxidase 4 (GPX4), and mitigated the excessive expression of long-chain acyl-CoA synthetase family member 4 (ACSL4). In oxygen-glucose deprivation/reoxygenation-treated HT22 cells, KBs maintained GPX4 levels, suppressed ACSL4 expression, and preserved the mitochondrial cristae number. However, the effect of KBs on the expression of GPX4, ACSL4, and the number of mitochondrial cristae was blocked by erastin. Moreover, both RIPostC and KBs reduced total iron and ferrous ion content by repressing iron transporters both in vitro and in vivo. In conclusion, KBs-induced mitigation of ferroptosis could represent a new therapeutic mechanism for RIPostC in treating stroke.

Middle-age abolishes cardioprotection conferred by thioredoxin-1 in mice.

Thioredoxin-1 (Trx1) has cardioprotective effects on ischemia/reperfusion (I/R) injury, although its role in ischemic postconditioning (PostC) in middle-aged mice is not understood. This study aimed to evaluate if combining two cardioprotective strategies, such as Trx1 overexpression and PostC, could exert a synergistic effect in reducing infarct size in middle-aged mice. Young or middle-aged wild-type mice (Wt), transgenic mice overexpressing Trx1, and dominant negative (DN-Trx1) mutant of Trx1 mice were used. Mice hearts were subjected to I/R or PostC protocol. Infarct size, hydrogen peroxide (H2O2) production, protein nitration, Trx1 activity, mitochondrial function, and Trx1, pAkt and pGSK3ß expression were measured. PostC could not reduce infarct size even in the presence of Trx1 overexpression in middle-aged mice. This finding was accompanied by a lack of Akt and GSK3ß phosphorylation, and Trx1 expression (in Wt group). Trx1 activity was diminished and H2O2 production and protein nitration were increased in middle-age. The respiratory control rate dropped after I/R in Wt-Young and PostC restored this value, but not in middle-aged groups. Our results showed that Trx1 plays a key role in the PostC protection mechanism in young but not middle-aged mice, even in the presence of Trx1 overexpression.

Effect of ischaemic postconditioning on markers of myocardial injury in ST-elevation myocardial infarction: a meta-analysis.

OBJECTIVES: This study aimed to perform a meta-analysis of the short-term impact of ischaemic postconditioning (IPoC) on myocardial injury in ST elevation myocardial infarction (STEMI) using surrogate cardiac biomarkers. METHODS: Eligible studies were identified using several article databases. Randomised controlled trials published between 1 January 2000 and 1 December 2021 comparing IPoC to standard of therapy in STEMI patients were included in the search. Outcomes included surrogates of myocardial injury, specifically peak troponin, creatine-kinase (CK) and CK myoglobin binding (CK-MB) enzyme levels. RESULTS: 11 articles involving 1273 patients reported on CK-MB and 8 studies involving 505 patients reported on CK. Few studies used troponin as an outcome, thus, a subanalysis of troponin dynamics was not performed. Meta-regression analysis demonstrated no significant effect of IPoC on peak CK-MB (effect size -0.41, 95% CI -1.15 to 0.34) or peak CK (effect size -0.42, 95% CI -1.20 to 0.36). Linear regression analysis demonstrated a significant correlation between a history of smoking and CK-MB in the IPoC group (p=0.038). CONCLUSIONS: IPoC does not seem to protect against myocardial injury in STEMI, except possibly in smokers. These results resonate with some studies using imaging techniques to ascertain myocardial damage. More research using troponin and cardiac imaging should be pursued to better assess the effects of IPoC on cardiovascular outcomes in STEMI.

Remote ischemic postconditioning alleviates cerebral ischemic injury through SERCA2/endoplasmic reticulum stress-mediated apoptosis.

Remote ischemic postconditioning (RIPostC) alleviates brain ischemic injury through several pathways, including endoplasmic reticulum (ER) stress modulation. Sarco endoplasmic reticulum Ca2+ -ATPase(SERCA2) which plays vital role in calcium homeostasis regulation could modulate ER stress logically. This study aimed to investigate whether RIPostC exerts its neuroprotective effect by reducing ER stress mediated by SERCA2. Male SD rats underwent transient middle cerebral artery occlusion (tMCAO) for 2 h followed by reperfusion, with the RIPostC group undergoing 3 cycles of bilateral femoral artery clamping and reperfusion at the beginning of reperfusion. Stroke outcome was assessed based on infarct volume and neurological function evaluation. Protein levels of SERCA2 and other ER stress markers were measured using Western blotting, immunofluorescence, and immunohistochemistry techniques. Compared to the sham group, we observed that RIPostC can effectively reduce cerebral infarct volume after I/R (34.55%: 21.03%; p = .004) and improve neurological function deficit (9.67:12.5; p = .029). Additionally, RIPostC increased SERCA2 protein expression and decreased the protein level of glucose-regulated protein 78 (GRP78), phosphorylation of eukaryotic translation initiation factor 2α (p-eIF2α) and CCAAT/EBP homologous protein (CHOP). Furthermore, B-cell lymphoma-2 (Bcl-2) expression was increased, while Bcl-2-associated X protein (Bax) and cleaved-caspase-3 was decreased in response to application of RIPostC. Our results suggest that RIPostC improves the prognosis of tMCAO rats, possibly by inhibiting the ER stress mediated by SERCA2, facilitating apoptosis downregulation. The significance of this study is to provide a theoretical basis for further exploring the protective mechanism of ischemic stroke by RIPostC. RESEARCH HIGHLIGHTS: Our results suggest that RIPostC improves the prognosis of tMCAO rats, possibly by inhibiting the ER stress mediated by SERCA2, facilitating apoptosis downregulation, thus achieving a neuroprotective effect.

Cerebral protective effect of in situ and remote ischemic postconditioning on ischemic stroke rat via the TGFß1-Smad2/3 signaling pathway.

Patients with acute ischemic stroke achieve inadequate benefit due to the short therapeutic window for thrombolysis and the risk of ischemia/reperfusion (IR) injury. Ischemic postconditioning induces endogenous cerebral protection for acute ischemic stroke, although the protective mechanisms associated with ischemic postconditioning haven't been well clarified. In present study, the rat models of ischemic cerebral stroke with in situ and remote ischemic postconditioning (ISP and RIP) were established successfully. The Zea Longa and the modified neurological severity scoring (mNSS) were carried out to evaluate neurological function in the rats, while the open field test was explored to estimate their autonomic athletic ability. The 2,3,5-riphenyltetrazolium chloride (TTC) staining method was used to measure the size of the infarcts. TUNEL and Nissl's staining were used to detect the apoptosis rate of cells in the ischemic penumbra, with the expression of TGFß1, Smad2, and Smad3 in the ischemic penumbra and serum detected by immunohistochemical staining, qRT-PCR, Western blots, and ELISA analysis. We showed that application of both types of ischemic postconditioning had cerebral protective effects for the ischemic stroke rats, that included effective reduction in the volume of cerebral infarction, alleviation of apoptosis and inflammation in the ischemic penumbra, and promotion of recovery of neurological function. These effects included significantly enriched gene ontology (GO) terms after RIP intervention that were related to TGFß1, increased protein levels of TGFß1 and decreased levels of p-Smad2/3 and smad3 following RIP intervention. We showed that the TGFß1-Smad2/3 signaling pathway was associated with the cerebral protection of ischemic postconditioning.

Neuroadaptive Biochemical Mechanisms of Remote Ischemic Conditioning.

This review summarizes the currently known biochemical neuroadaptive mechanisms of remote ischemic conditioning. In particular, it focuses on the significance of the pro-adaptive effects of remote ischemic conditioning which allow for the prevention of the neurological and cognitive impairments associated with hippocampal dysregulation after brain damage. The neuroimmunohumoral pathway transmitting a conditioning stimulus, as well as the molecular basis of the early and delayed phases of neuroprotection, including anti-apoptotic, anti-oxidant, and anti-inflammatory components, are also outlined. Based on the close interplay between the effects of ischemia, especially those mediated by interaction of hypoxia-inducible factors (HIFs) and steroid hormones, the involvement of the hypothalamic-pituitary-adrenocortical system in remote ischemic conditioning is also discussed.

The Effect of Remote Ischemic Postconditioning on Quality of Life and Clinical Events after an Ischemic Stroke.

OBJECTIVES: Repeated remote ischemic postconditioning (rIPostC) may be an easily applicable treatment following ischemic stroke to improve quality of life (QoL) and clinical outcomes. rIPostC consists of repeated, brief periods of limb ischemia (through inflation of a blood pressure cuff), followed by reperfusion. This study investigated the 1-year follow-up of rIPostC on QoL and clinical events. METHODS: As part of a randomized controlled trial, adult patients with an ischemic stroke within 24 hours after onset of symptoms were randomized to repeated rIPostC or sham-conditioning. rIPostC was applied twice daily during hospitalization (maximum of 4 days). QoL and patientreported outcome measures (PROMs) were assessed at 12-week and 1-year follow-ups. Additionally, we explored the effect of repeated rIPostC on clinical events (recurrent cerebrovascular events, hospitalization, and mortality). RESULTS: The trial was preliminarily stopped due to limitations in recruitment after the inclusion of 88 patients (rIPostC: 40; sham-conditioning: 48) (70 years, 68% male). Questionnaires were returned by 69 (78%) and 63 (72%) participants after 12 weeks and 1 year, respectively. The median difference of the stroke-specific QoL between rIPostC and sham-conditioning was 0.05 (p =0.986) and -0.16 (p =0.654) after 12 weeks and 1-year, respectively. No significant effect of rIPostC on the different domains of PROMs was detected. We observed no between-group differences in recurrent cerebrovascular events, hospitalization, or all-cause mortality (Hazard Ratios p >0.05). CONCLUSION: In this exploratory analysis, we observed no significant difference between repeated rIPostC and usual care on QoL and clinical outcomes at 12 weeks and 1 year in patients with an ischemic stroke. CLINICAL TRIAL REGISTRATION NUMBER: NTR6880.

Effect of remote ischemic postconditioning on left ventricular ejection fraction in patients with ST-segment elevation myocardial infarction undergoing primary percutaneous coronary intervention.

BACKGROUND: Ischemic conditioning may help patients with ST-segment elevation myocardial infarction (STEMI) to limit ventricular remodeling. OBJECTIVES: To investigate the effect of remote ischemic postconditioning (RIPC) on left ventricular function during primary percutaneous coronary intervention (PPCI) in patients with STEMI. MATERIAL AND METHODS: Pre- and post-test intervention study with a total of 60 STEMI patients. Patients were divided in two groups: with and without RIPC. RESULTS: During the 6-month follow-up, a significant difference in left ventricular ejection fraction was observed in patients who underwent PPCI, which was higher in the group with RIPC in comparison with the group without RIPC: 1.0% (-1.0 to 4.3) vs. -1.0% (-4.0 to 1.3), p = 0.033. In addition, at 6-month measurement, left ventricular end-systolic volume in patients without RIPC was higher in comparison with their counterparts: 79.3 ± 30.5 mL vs. 64.4 ± 21.4 mL, p = 0.032. CONCLUSIONS: RIPC shows favorable effects on left ventricular function and, therefore, in the future, it could be a potential cardioprotective strategy against ischemia-reperfusion injury in STEMI patients.

ANTECEDENTES: En los pacientes con infarto agudo de miocardio con elevación del segmento ST (IAMCEST), el acondicionamiento isquémico puede ayudar a limitar la remodelación ventricular. OBJETIVOS: Investigar el efecto del posacondicionamiento isquémico remoto (PAIR) en la función del ventrículo izquierdo durante la intervención coronaria percutánea primaria (ICPP) en pacientes con IAMCEST. MATERIAL Y MÉTODOS: Estudio de intervención pre y posprueba con un total de 60 pacientes con IAMCEST. Los pacientes fueron divididos en dos grupos: con y sin PAIR. RESULTADOS: En el seguimiento de seis meses se observó una diferencia significativa en la fracción de eyección del ventrículo izquierdo en pacientes con ICPP, la cual fue mayor en el grupo con PAIR en comparación con el grupo sin PAIR: 1.0 (−1.0 a 4.3) versus −1.0 (−4.0 a ­1.3), p = 0.033. En la medición de seis meses, el volumen sistólico final del ventrículo izquierdo en los pacientes sin PAIR fue mayor en comparación con el grupo homólogo: 79.3 ± 30.5 mL versus 64.4 ± 21.4 mL, p = 0.032. CONCLUSIONES: PAIR muestra efectos favorables en la función ventricular izquierda y, por lo tanto, en el futuro podría ser una estrategia cardioprotectora potencial contra la lesión por isquemia-reperfusión en pacientes con IAMCEST.

Remote Ischemic Conditioning for Acute Stroke: The RESIST Randomized Clinical Trial.

Importance: Despite some promising preclinical and clinical data, it remains uncertain whether remote ischemic conditioning (RIC) with transient cycles of limb ischemia and reperfusion is an effective treatment for acute stroke. Objective: To evaluate the effect of RIC when initiated in the prehospital setting and continued in the hospital on functional outcome in patients with acute stroke. Design, Setting, and Participants: This was a randomized clinical trial conducted at 4 stroke centers in Denmark that included 1500 patients with prehospital stroke symptoms for less than 4 hours (enrolled March 16, 2018, to November 11, 2022; final follow-up, February 3, 2023). Intervention: The intervention was delivered using an inflatable cuff on 1 upper extremity (RIC cuff pressure, ≤200 mm Hg [n = 749] and sham cuff pressure, 20 mm Hg [n = 751]). Each treatment application consisted of 5 cycles of 5 minutes of cuff inflation followed by 5 minutes of cuff deflation. Treatment was started in the ambulance and repeated at least once in the hospital and then twice daily for 7 days among a subset of participants. Main Outcomes and Measures: The primary end point was improvement in functional outcome measured as a shift across the modified Rankin Scale (mRS) score (range, 0 [no symptoms] to 6 [death]) at 90 days in the target population with a final diagnosis of ischemic or hemorrhagic stroke. Results: Among 1500 patients who were randomized (median age, 71 years; 591 women [41%]), 1433 (96%) completed the trial. Of these, 149 patients (10%) were diagnosed with transient ischemic attack and 382 (27%) with a stroke mimic. In the remaining 902 patients with a target diagnosis of stroke (737 [82%] with ischemic stroke and 165 [18%] with intracerebral hemorrhage), 436 underwent RIC and 466 sham treatment. The median mRS score at 90 days was 2 (IQR, 1-3) in the RIC group and 1 (IQR, 1-3) in the sham group. RIC treatment was not significantly associated with improved functional outcome at 90 days (odds ratio [OR], 0.95; 95% CI, 0.75 to 1.20, P = .67; absolute difference in median mRS score, -1; -1.7 to -0.25). In all randomized patients, there were no significant differences in the number of serious adverse events: 169 patients (23.7%) in the RIC group with 1 or more serious adverse events vs 175 patients (24.3%) in the sham group (OR, 0.97; 95% CI, 0.85 to 1.11; P = .68). Upper extremity pain during treatment and/or skin petechia occurred in 54 (7.2%) in the RIC group and 11 (1.5%) in the sham group. Conclusions and Relevance: RIC initiated in the prehospital setting and continued in the hospital did not significantly improve functional outcome at 90 days in patients with acute stroke. Trial Registration: ClinicalTrials.gov Identifier: NCT03481777.

Ischemic Postconditioning Confers No Benefit to Left Ventricular Systolic Function: A Meta-Analysis of Cardiac Magnetic Resonance Imaging Results.

Ischemic postconditioning (IPoC) is a technique suggested to reduce reperfusion injury in patients suffering acute ST-elevation myocardial infarction (STEMI), although its use is highly controversial. This meta-analysis aimed to evaluate the effect of IPoC with percutaneous coronary intervention in patients with acute STEMI, as measured by follow-up left ventricular ejection fraction (LVEF) on cardiac magnetic resonance imaging. The investigators searched PubMed, Embase, and Web of Science for all randomized controlled trials published during the last 2 decades. After the removal of duplicates, 2,021 articles from online databases had been identified using relevant search criteria. The included randomized controlled trials had studied patients with acute STEMI and Thrombolysis in Myocardial Infarction flow 0 to 1 at presentation and had measured follow-up LVEF using cardiac magnetic resonance imaging. Overall, 11 studies (n = 1,339 patients) qualified for inclusion. In each study, the control group did not differ significantly from the experimental group. The pooled data from included studies were analyzed using standardized mean difference between IPoC and control groups, and the 95% confidence interval for LVEF; the results were visualized using a forest plot. Bivariate regression analyses and 1-way analyses of LVEF coefficient ratios were done to isolate for various clinical and procedural parameters. An analysis of pooled data of the IPoC (n = 674) and control (n = 665) groups showed that IPoC did not significantly impact follow-up LVEF (using standardized mean difference 0.10, 95% confidence interval 0.00 to 0.21). Further analysis showed that IPoC did not improve follow-up LVEF when isolating for relevant clinical and procedural parameters. In conclusion, the use of IPoC as an adjunctive therapy to percutaneous coronary intervention seemingly provides no benefit to left ventricular systolic function, as quantified with cardiac magnetic resonance imaging, in patients with acute STEMI with Thrombolysis in Myocardial Infarction flow 0 to 1.

Anti-Inflammatory and Antipruritic Effects of Remote Ischaemic Postconditioning in a Mouse Model of Experimental Allergic Contact Dermatitis.

Background and Objectives: Allergic contact dermatitis is a common type IV hypersensitivity reaction characterised by redness, itching, oedema and thickening of the skin. It occurs in about 7% of the population and its incidence is increasing. It has been observed that the preconditioning of tissues by exposing them to transient ischemia increases resistance to subsequent permanent ischemia, and this phenomenon is called ischemic preconditioning. It has been shown that conditioning in one organ can also protect other organs. The protective effect of remote ischemic preconditioning is thought to be based on the induction of anti-inflammatory responses. The aim of this project was to investigate the anti-inflammatory and antipruritic effects of remote ischemic postconditioning in a mouse model of experimental allergic contact dermatitis. Methods: Experimental allergic contact dermatitis was induced with 1-fluoro-2,4-dinitrobenzene. Remote ischemic postconditioning was performed at 3 and 25 h after the challenge. Ear thickness and number of scratches 24 and 48 h after challenge, as well as cytokine levels and the infiltration of mast cells, neutrophils, CD4+ and CD8+ T lymphocytes in serum and ear tissue at 48 h were measured to determine the effect of RIPsC. Results: Remote ischemic postconditioning decreased ear thickness, one of the symptoms of allergic contact dermatitis (p < 0.0001). It had no significant effect on the number of scratches. It reduced serum IL-17 levels (p < 0.01). It alleviated local inflammation by suppressing CD8+ T lymphocyte and neutrophil infiltration. Conclusions: It was concluded that remote ischemic postconditioning may alleviate the symptoms of allergic contact dermatitis by suppressing CD8+ T lymphocyte and neutrophil infiltration and reducing IL-17 secretion.