Propofol Induces Cardioprotection Against Ischemia-Reperfusion Injury via Suppression of Transient Receptor Potential Vanilloid 4 Channel

Transient receptor potential vanilloid 4 channel inhibition attenuates lung ischemia-reperfusion injury in a porcine lung transplant model

OBJECTIVE

Transient receptor potential vanilloid 4 (TRPV4) is a nonselective cation channel important in many physiological and pathophysiological processes, including pulmonary disease. Using a murine model, we previously demonstrated that TRPV4 mediates lung ischemia-reperfusion injury, the major cause of primary graft dysfunction after transplant. The current study tests the hypothesis that treatment with a TRPV4 inhibitor will attenuate lung ischemia-reperfusion injury in a clinically relevant porcine lung transplant model.

METHODS

A porcine left-lung transplant model was used. Animals were randomized to 2 treatment groups (n = 5/group): vehicle or GSK2193874 (selective TRPV4 inhibitor). Donor lungs underwent 30 minutes of warm ischemia and 24 hours of cold preservation before left lung allotransplantation and 4 hours of reperfusion. Vehicle or GSK2193874 (1 mg/kg) was administered to the recipient as a systemic infusion after recipient lung explant. Lung function, injury, and inflammatory biomarkers were compared.

RESULTS

After transplant, left lung oxygenation was significantly improved in the TRPV4 inhibitor group after 3 and 4 hours of reperfusion. Lung histology scores and edema were significantly improved, and neutrophil infiltration was significantly reduced in the TRPV4 inhibitor group. TRPV4 inhibitor-treated recipients had significantly reduced expression of interleukin-8, high mobility group box 1, P-selectin, and tight junction proteins (occludin, claudin-5, and zonula occludens-1) in bronchoalveolar lavage fluid as well as reduced angiopoietin-2 in plasma, all indicative of preservation of endothelial barrier function.

CONCLUSIONS

Treatment of lung transplant recipients with TRPV4 inhibitor significantly improves lung function and attenuates ischemia-reperfusion injury. Thus, selective TRPV4 inhibition may be a promising therapeutic strategy to prevent primary graft dysfunction after transplant.

Circulating factors, in both donor and ex-situ heart perfusion, correlate with heart recovery in a pig model of DCD

BACKGROUND

Heart transplantation with donation after circulatory death and ex-situ heart perfusion offers excellent outcomes and increased transplantation rates. However, improved graft evaluation techniques are required to ensure effective utilization of grafts. Therefore, we investigated circulating factors, both in-situ and ex-situ, as potential biomarkers for cardiac graft quality.

METHODS

Circulatory death was simulated in anesthetized male pigs with warm ischemic durations of 0, 10, 20, or 30 minutes. Hearts were explanted and underwent ex-situ perfusion for 3 hours in an unloaded mode, followed by left ventricular loading for 1 hour, to evaluate cardiac recovery (outcomes). Multiple donor blood and ex-situ perfusate samples were used for biomarker evaluation with either standard biochemical techniques or nuclear magnetic resonance spectroscopy.

RESULTS

Circulating adrenaline, both in the donor and at 10 minutes ex-situ heart perfusion, negatively correlated with cardiac recovery (p < 0.05 for all). We identified several new potential biomarkers for cardiac graft quality that can be measured rapidly and simultaneously with nuclear magnetic resonance spectroscopy. At multiple timepoints during unloaded ex-situ heart perfusion, perfusate levels of acetone, betaine, creatine, creatinine, fumarate, hypoxanthine, lactate, pyruvate and succinate (p < 0.05 for all) significantly correlated with outcomes; the optimal timepoint being 60 minutes.

CONCLUSIONS

In heart donation after circulatory death, circulating adrenaline levels are valuable for cardiac graft evaluation. Nuclear magnetic resonance spectroscopy is of particular interest, as it measures multiple metabolites in a short timeframe. Improved biomarkers may allow more precision and therefore better support clinical decisions about transplantation suitability.

Effect of Propofol in the Cardiovascular System and its Related Mechanism Research Progress

Propofol is the most widely used short-acting intravenous anesthetic in clinical practice. Existing studies have shown that propofol has many effects on the cardiovascular system in addition to its anesthetic effect. Propofol can antagonize a variety of tachyarrhythmias and reduce the risk of recurrence, regulate autonomic balance of the heart, modulate circulatory dynamics, thereby increasing blood perfusion to vital organs such as the kidney, intestine, and brain, and exert myocardial protection and cerebral protection during ischemia-reperfusion injury. In this paper, we review the potential mechanisms of these effects and provide and ideas for future research and novel drug development of propofol and its derivatives in cardiac electrophysiology and circulatory dynamics.

Tetrandrine downregulates TRPV2 expression to ameliorate myocardial ischemia/reperfusion injury in rats via regulation of cardiomyocyte apoptosis, calcium homeostasis and mitochondrial function

Our previous study has indicated that tetrandrine (TET) can target miR-202-5p to repress the activation of transient receptor potential vanilloid type 2 (TRPV2), eventually ameliorating the progression of myocardial ischemia/reperfusion injury (MI/RI). This study is aimed to further ascertain the detailed mechanisms between TET and TRPV2 in MI/RI pathogenesis. Here, a myocardial I/R injury rat model and a hypoxia-reoxygenation (H/R) model in rat myocardial cell line (H9C2 cells) were established. We reported that pronounced upregulation of TRPV2 was observed in I/R rats and H/R-induced H9C2 cells. Silencing of TRPV2 could improve cardiac function and myocardial injury, reduced infarction size, and promoted cardiomyocyte proliferation in I/R rats. In I/R rats or H/R-induced H9C2 cells, cardiomyocyte apoptosis was inhibited by knocking-down TRPV2. Meanwhile, the silenced TRPV2 or TET treatment ameliorated the damaged mitochondrial structure, mitigated ROS generation, restored the impaired ΔΨM, inhibited mPTP opening and alleviated Ca2+ overload in H/R-induced H9C2 cells. The results obtained from the overexpression of TRPV2 were contrary to those depicted above. Moreover, TET could downregulate TRPV2 expression, while the overexpression of TRPV2 could reverse the above protective effects of TET in H/R-induced H9C2 cells. The results indicated that TET may function as a TRPV2 blocking agent, thereby attenuating the progression of MI/RI through modulation of cardiomyocyte apoptosis, calcium homeostasis and mitochondrial function. These findings offer a theoretical foundation for potential clinical application of TET therapy in patients with MI/RI.

Spotlight on HOX cluster‑embedded antisense lncRNAs in cardiovascular diseases (Review)

Atherosclerosis is a complex and chronic inflammatory disease driven by multiple pathophysiological processes that are responsible for diverse cardiovascular events. Atherosclerotic cardiovascular disease, despite substantial triumphs in primary and secondary prevention, remains a dominant epidemic that impairs human health. Therefore, deciphering the pathogenesis of atherosclerosis will provide a real‑world translational understanding. Homeobox cluster‑embedded antisense long non‑coding RNAs (HOX‑lncRNAs), a nascent class of lncRNA molecules with versatile roles in cancer, can also orchestrate various cell functions in cardiovascular disorders and have thus captured the attention of many researchers. Subsequently, numerous studies have demonstrated the role of HOX‑lncRNAs as potential modulators of atherosclerosis. Nevertheless, given that the understanding of HOX‑lncRNAs in atherosclerosis is only just emerging, ongoing research must be initiated to thoroughly pinpoint such causal roles. The present review aimed to highlight the important contributions of HOX‑lncRNAs to atherosclerosis and other pivotal biological processes related to cardiovascular disease. The review concludes with a discussion of the limitations, outlook, challenges and possible solutions associated with HOX‑lncRNAs in atherosclerosis. Looking forward, this may lead to extraordinary breakthroughs in revealing the molecular underpinnings of HOX‑lncRNAs and may offer a promising yet challenging landscape for robust therapeutic strategies for atherosclerosis and/or associated cardiovascular disorders.

Transient receptor potential vanilloid 4 (TRPV4) in neutrophils enhances myocardial ischemia/reperfusion injury

The Ca2+-permeable TRPV4 cation channel is expressed in neutrophils and contributes to myocardial ischemia/reperfusion injury. Here we tested the hypotheses that TRPV4 promotes neutrophil activation and subsequently aggregates myocardial ischemia/reperfusion injury. TRPV4 protein was confirmed in neutrophils, and its function was assessed by the current and intracellular Ca2+ concentration elevations evoked by TRPV4 agonists. Furthermore, TRPV4 agonists dose-dependently promoted migration toward fMLP, reactive oxygen species production, and myeloperoxidase release, which were prevented by pretreatment with a selective TRPV4 antagonist, in neutrophils from TRPV4 knockout mice, Ca2+-free medium, or BAPTA-AM + Ca2+-free medium. Blockade of TRPV4 also inhibited the effects of commonly used neutrophil activators fMLP and PMA. Mechanically, TRPV4 regulated neutrophil activation, particularly reactive oxygen species production, by affecting PKCα, P38, and AKT via Ca2+ signaling. In addition, isolated hearts infused with neutrophils from wild-type mice showed additional myocardial ischemia/reperfusion injuries but not those infused with TRPV4 knockout. Our study reveals that TRPV4-mediated neutrophil activation enhances myocardial ischemia/reperfusion injury, and it might be a novel therapeutic target for myocardial ischemia/reperfusion injury and other neutrophil-mediated inflammatory diseases.

General anaesthesia-related complications of gut motility with a focus on cholinergic mechanisms, TRP channels and visceral pain

General anesthesia produces multiple side effects. Notably, it temporarily impairs gastrointestinal motility following surgery and causes the so-called postoperative ileus (POI), a multifactorial and complex condition that develops secondary to neuromuscular failure and mainly affects the small intestine. There are currently limited medication options for POI, reflecting a lack of comprehensive understanding of the mechanisms involved in this complex condition. Notably, although acetylcholine is one of the major neurotransmitters initiating excitation-contraction coupling in the gut, cholinergic stimulation by prokinetic drugs is not very efficient in case of POI. Acetylcholine when released from excitatory motoneurones of the enteric nervous system binds to and activates M2 and M3 types of muscarinic receptors in smooth muscle myocytes. Downstream of these G protein-coupled receptors, muscarinic cation TRPC4 channels act as the major focal point of receptor-mediated signal integration, causing membrane depolarisation accompanied by action potential discharge and calcium influx via L-type Ca²⁺ channels for myocyte contraction. We have recently found that both inhalation (isoflurane) and intravenous (ketamine) anesthetics significantly inhibit this muscarinic cation current (termed mI _CAT) in ileal myocytes, even when G proteins are activated directly by intracellular GTPγS, i.e., bypassing muscarinic receptors. Here we aim to summarize Transient Receptor Potential channels and calcium signalling-related aspects of the cholinergic mechanisms in the gut and visceral pain, discuss exactly how these may be negatively impacted by general anaesthetics, while proposing the receptor-operated TRPC4 channel as a novel molecular target for the treatment of POI.

Microvascular Leakage as Therapeutic Target for Ischemia and Reperfusion Injury

Reperfusion injury is a very common complication of various indicated therapies such as the re-opening of vessels in the myocardium or brain as well as reflow in hemodynamic shutdown (cardiac arrest, severe trauma, aortic cross-clamping). The treatment and prevention of reperfusion injury has therefore been a topic of immense interest in terms of mechanistic understanding, the exploration of interventions in animal models and in the clinical setting in major prospective studies. While a wealth of encouraging results has been obtained in the lab, the translation into clinical success has met with mixed outcomes at best. Considering the still very high medical need, progress continues to be urgently needed. Multi-target approaches rationally linking interference with pathophysiological pathways as well as a renewed focus on aspects of microvascular dysfunction, especially on the role of microvascular leakage, are likely to provide new insights.

Activation of transient receptor potential vanilloid 4 is involved in pressure overload-induced cardiac hypertrophy

Previous studies, including our own, have demonstrated that transient receptor potential vanilloid 4 (TRPV4) is expressed in hearts and implicated in cardiac remodeling and dysfunction. However, the effects of TRPV4 on pressure overload-induced cardiac hypertrophy remain unclear. In this study, we found that TRPV4 expression was significantly increased in mouse hypertrophic hearts, human failing hearts, and neurohormone-induced hypertrophic cardiomyocytes. Deletion of TRPV4 attenuated transverse aortic constriction (TAC)-induced cardiac hypertrophy, cardiac dysfunction, fibrosis, inflammation, and the activation of NFκB - NOD - like receptor pyrin domain-containing protein 3 (NLRP3) in mice. Furthermore, the TRPV4 antagonist GSK2193874 (GSK3874) inhibited cardiac remodeling and dysfunction induced by TAC. In vitro, pretreatment with GSK3874 reduced the neurohormone-induced cardiomyocyte hypertrophy and intracellular Ca2+ concentration elevation. The specific TRPV4 agonist GSK1016790A (GSK790A) triggered Ca2+ influx and evoked the phosphorylation of Ca2+/calmodulin-dependent protein kinase II (CaMKII). But these effects were abolished by removing extracellular Ca2+ or GSK3874. More importantly, TAC or neurohormone stimulation-induced CaMKII phosphorylation was significantly blocked by TRPV4 inhibition. Finally, we show that CaMKII inhibition significantly prevented the phosphorylation of NFκB induced by GSK790A. Our results suggest that TRPV4 activation contributes to pressure overload-induced cardiac hypertrophy and dysfunction. This effect is associated with upregulated Ca2+/CaMKII mediated activation of NFκB-NLRP3. Thus, TRPV4 may represent a potential therapeutic drug target for cardiac hypertrophy and dysfunction after pressure overload.

Protective effects of adipose-derived biogenic nanoparticles on the pulmonary microvascular endothelial barrier in mice with ventilator-induced lung injury via the TRPV4/ROCK1 signalling pathway

PURPOSE

The "obesity paradox" phenomenon occurs in critically ill patients who receive mechanical ventilation. Our previous studies found that the adipose-derived exosomes secreted by obese mice have a protective effect on the pulmonary microvascular endothelial barrier. However, the extraction of exosomes is cumbersome, their yield is low, and their storage is difficult. After further research, we discovered a new type of adipose-derived bioactive material called: lipoaspirate nanoparticles (Lipo-NPs).

METHODS

Lipo-NPs were extracted and identified using a tangential flow filtration system. The Lipo-NPs were used as an intervention in ventilator-induced lung injury (VILI) models in vivo and in vitro to investigate whether they have a protective effect on lung tissue damage (haematoxylin and eosin staining), lung barrier function (lung wet/dry [W/D] weight ratio, protein concentration in bronchoalveolar lavage fluid (BALF), and Vascular endothelial (VE)-expression), as well as their related mechanisms.

RESULTS

In both in vivo and in vitro studies, Lipo-NPs can attenuate lung injury, reduce lung W/D ratio and protein concentration in BALF, and augment the expression of the adhesion link-protein VE-cadherin, thus playing a protective role in lung barrier function. This protective effect involves the activation of the transient receptor potential vanilloid 4 (TRPV4)/Rho-associated kinase1 (ROCK1) signalling pathway. We further verified the role of this signalling pathway via activation and inhibition of TRPV4 and ROCK1. Moreover, phosphorylation of myosin light chain 2 (MLC2) regulates F-actin and is a target of the ROCK pathway.

CONCLUSION

Lipo-NPs can enhance the expression of VE-cadherin by inhibiting the TRPV4/ROCK1/pMLC2 signalling pathway in the mechanical ventilation model, thereby exerting a protective effect on the VILI pulmonary microvascular endothelial barrier.

Putative Roles of Astrocytes in General Anesthesia

General anesthetics are a mainstay of modern medicine, and although much progress has been made towards identifying molecular targets of anesthetics and neural networks contributing to endpoints of general anesthesia, our understanding of how anesthetics work remains unclear. Reducing this knowledge gap is of fundamental importance to prevent unwanted and life-threatening side-effects associated with general anesthesia. General anesthetics are chemically diverse, yet they all have similar behavioral endpoints, and so for decades, research has sought to identify a single underlying mechanism to explain how anesthetics work. However, this effort has given way to the 'multiple target hypothesis' as it has become clear that anesthetics target many cellular proteins, including GABAA receptors, glutamate receptors, voltage-independent K+ channels, and voltagedependent K+, Ca2+ and Na+ channels, to name a few. Yet, despite evidence that astrocytes are capable of modulating multiple aspects of neural function and express many anesthetic target proteins, they have been largely ignored as potential targets of anesthesia. The purpose of this brief review is to highlight the effects of anesthetic on astrocyte processes and identify potential roles of astrocytes in behavioral endpoints of anesthesia (hypnosis, amnesia, analgesia, and immobilization).

Interleukin-6-Mediated-Ca2+ Handling Abnormalities Contributes to Atrial Fibrillation in Sterile Pericarditis Rats

Pre-existing Ca²⁺ handling abnormalities constitute the arrhythmogenic substrate in patients developing postoperative atrial fibrillation (POAF), a common complication after cardiac surgery. Postoperative interleukin (IL)-6 levels are associated with atrial fibrosis in several animal models of POAF, contributing to atrial arrhythmias. Here, we hypothesize that IL-6-mediated-Ca²⁺ handling abnormalities contribute to atrial fibrillation (AF) in sterile pericarditis (SP) rats, an animal model of POAF. SP was induced in rats by dusting atria with sterile talcum powder. Anti-rat-IL-6 antibody (16.7 μg/kg) was administered intraperitoneally at 30 min after the recovery of anesthesia. In vivo electrophysiology, ex vivo optical mapping, western blots, and immunohistochemistry were performed to elucidate mechanisms of AF susceptibility. IL-6 neutralization ameliorated atrial inflammation and fibrosis, as well as AF susceptibility in vivo and the frequency of atrial ectopy and AF with a reentrant pattern in SP rats ex vivo. IL-6 neutralization reversed the prolongation and regional heterogeneity of Ca²⁺ transient duration, relieved alternans, reduced the incidence of discordant alternans, and prevented the reduction and regional heterogeneity of the recovery ratio of Ca²⁺ transient. In agreement, western blots showed that IL-6 neutralization reversed the reduction in the expression of ryanodine receptor 2 (RyR2) and phosphorylated phospholamban. Acute IL-6 administration to isolated rat hearts recapitulated partial Ca²⁺ handling phenotype in SP rats. In addition, intraperitoneal IL-6 administration to rats increased AF susceptibility, independent of fibrosis. Our results reveal that IL-6-mediated-Ca²⁺ handling abnormalities in SP rats, especially RyR2-dysfunction, independent of IL-6-induced-fibrosis, early contribute to the development of POAF by increasing propensity for arrhythmogenic alternans.

Anesthetics mediated the immunomodulatory effects via regulation of TLR signaling

Anesthetics have been widely used in surgery and found to suppress inflammatory injury and affect the outcomes of the surgery and diseases. In contrast, anesthetics are also found to induce neuronal injury and inflammation. However, the immune-modulation mechanism of anesthetics is still not clear. Recent studies have shown that the immune-modulation of anesthetics is associated with the regulation of toll-like receptor (TLR)-mediated signaling. Moreover, the regulation of anesthetics in TLR signaling is related to modulations of non-coding RNAs (nc RNAs). Consistently, nc RNAs are mainly divided into micro RNAs (miRs) and long non-coding RNAs (lnc RNAs), which have been found to exert regulatory effects on the immune system. In this review, we summarize the immunomodulatory functions of the widely used anesthetic agents, which are associated with regulation of TLR signaling. In addition, we also focus on the roles of nc RNAs induced by anesthetics in regulations of TLR signaling.

Activation of transient receptor potential vanilloid 4 exacerbates myocardial ischemia-reperfusion injury via JNK-CaMKII phosphorylation pathway in isolated mice hearts

Previous studies, including our own, have demonstrated that transient receptor potential vanilloid 4 (TRPV4) is involved in myocardial ischemia-reperfusion (IR) injury, yet its underlying molecular mechanism remains unclear. In this study, we isolated mice hearts for a Langendorff perfusion test and used HL-1 myocytes for in vitro assessments. We first confirmed that TRPV4 agonist (GSK101) enhanced myocardial IR injury, as demonstrated by the reduced recovery of cardiac function, larger myocardial infarct size, and more apoptotic cells. We also found that GSK101 could further increase the phosphorylation of JNK and CaMKII in isolated hearts during IR. Notably, GSK101 dose-dependently evoked the phosphorylation of JNK and CaMKII in isolated normal hearts. All above GSK101-induced effects could be significantly blocked by the pharmacological inhibition or genetic ablation of TRPV4. More importantly, JNK inhibition (with SP600125) or CaMKII inhibition (with KN93 or in transgenic AC3-I mice) could prevent GSK101-induced myocardial injury during IR. In HL-1 myocytes, GSK101 triggered Ca²⁺ influx and evoked the phosphorylation of JNK and CaMKII but these effects were abolished by removing extracellular Ca²⁺ or in the presence of a TRPV4 antagonist. Finally, we showed that in HL-1 myocytes and isolated hearts during IR, JNK inhibition significantly inhibited the phosphorylation of CaMKII induced by GSK101 but CaMKII inhibition had no effect on JNK activation induced by GSK101. Our data suggest that TRPV4 activation exacerbates myocardial IR injury via the JNK-CaMKII phosphorylation pathway.

Case Report: Pink Urine Syndrome Following Exposure to Propofol: A Rare, Impressive but Benign Complication

Drug-induced changes in urine color induced by drugs may have clinical significance. Pink urine syndrome (PUS), which has been associated with urinary uric acid (UA) disorders, is most frequently reported in patients with morbid obesity undergoing gastric bypass surgery and/or from propofol anesthesia use in those who potentially have preexisting UA metabolism disorders. However, PUS has rarely occurred following exposure to propofol in non-obese patients, and literature on long-term follow-up after PUS is scarce. We report a case of PUS induced by propofol in a previously healthy non-obese woman after undergoing thoracoscopic wedge resection of pulmonary nodules under general anesthesia using propofol. The patient suddenly developed pink urine 4 h after surgery. A pink sediment rapidly precipitated at the bottom of the test tube following centrifugation of the urine. Amorphous, colorless UA-like crystals were identified under a polarizing microscope. The diagnosis of PUS was confirmed by examining the urinary UA concentration. The patient recovered and as followed-up for 1 month, during which she did not experience any urinary complications. To our knowledge, this is the first report to describe in detail a case of PUS caused by propofol in a non-obese patient with follow-up. PUS is usually benign and can resolve by rapidly on administering lactated Ringer’s solution; however, the potential risk of urinary complications, particularly UA lithiasis, should be fully realized.

Propofol Inhibits Ischemia/Reperfusion-Induced Cardiotoxicity Through the Protein Kinase C/Nuclear Factor Erythroid 2-Related Factor Pathway

Both hydrogen peroxide (H₂O₂, H) and ischemia/reperfusion (I/R) can damage cardiomyocytes, which was inhibited by propofol (P). The present research was designed to examine whether propofol can reduce myocardial I/R injury by activating protein kinase C (PKC)/nuclear factor erythroid-2-related factor 2 (NRF2) pathway in H9C2 cells and rat Langendorff models. H9C2 cells were disposed of no reagents (C), H₂O₂ for 24 h (H), propofol for 1 h before H₂O₂ (H+P), and chelerythrine (CHE, PKC inhibitor) for 1 h before propofol and H₂O₂ (H+P+CHE). N = 3. The PKC gene of H9C2 was knocked down by siRNA and overexpressed by phorbol 12-myristate 13-acetate (PMA, PKC agonist). The cell viability and the expressions of PKC, NRF2, or heme oxygenase-1(HO-1) were evaluated. Propofol significantly reduced H9C2 cell mortality induced by H₂O₂, and significantly increased NRF2 nuclear location and HO-1 expression, which were restrained by siRNA knockout of PKC and promoted by PMA. Rat hearts were treated with KrebsHenseleit solution for 120 min (C), with (I/R+P) or without (I/R) propofol for 20 min before stopping perfusion for 30 min and reperfusion for 60 min, and CHE for 10 min before treated with propofol. N = 6. The levels of lactate dehydrogenase (LDH), superoxide dismutase (SOD), and creatine kinase-MB (CK-MB) in perfusion fluid and antioxidant enzymes in the myocardium were assessed. I/R, which increased LDH and CK-MB expression and reduced SOD expression, boosted the pathological damage and infarcts of the myocardium after reperfusion. However, propofol restrained all these effects, an activity that was antagonized by CHE. The results suggest that propofol pretreatment protects against I/R injury by activating of PKC/NRF2 pathway.

Endothelial Transient Receptor Potential V4 Channels Mediate Lung Ischemia-Reperfusion Injury

BACKGROUND

Lung ischemia-reperfusion injury (IRI), involving severe inflammation and edema, is a major cause of primary graft dysfunction following transplant. Activation of transient receptor potential vanilloid 4 (TRPV4) channels modulates vascular permeability. Thus, this study tests the hypothesis that endothelial TRPV4 channels mediate lung IRI.

METHODS

C57BL/6 wild-type (WT), TRPV4^-/-, tamoxifen-inducible endothelial TRPV4 knockout (TRPV4_EC^-/-), and tamoxifen-treated control (TRPV4^fl/fl) mice underwent lung IR using a left lung hilar-ligation model (n≥6 mice/group). WT mice were also treated with a TRPV4-specific inhibitor (GSK2193874; 1mg/kg) (WT+GSK219). Partial pressure of oxygen (PaO₂), edema (wet-to-dry weight ratio), compliance, neutrophil infiltration, and cytokine concentrations in bronchioalveolar lavage fluid were assessed. Pulmonary microvascular endothelial cells (PMVECs) were characterized in vitro following exposure to hypoxia-reoxygenation.

RESULTS

Compared to WT, PaO₂ following IR was significantly improved in TRPV4^-/- mice (133.1±43.9 vs 427.8±83.1 mmHg, p<0.001) and WT+GSK219 mice (133.1±43.9 vs 447.0±67.6 mmHg, p<0.001). Pulmonary edema and neutrophil infiltration were also significantly reduced after IR in TRPV4^-/- and WT+GSK219 mice versus WT. TRPV4_EC^-/- mice following IR demonstrated significantly improved oxygenation versus control (109.2±21.6 vs 405.3±41.4 mmHg, p<0.001) as well as significantly improved compliance, and significantly less edema, neutrophil infiltration and proinflammatory cytokine production (TNF-α, CXCL1, IL-17, IFN-γ). Hypoxia-reoxygenation-induced permeability and CXCL1 expression by PMVECs was significantly attenuated by TRPV4 inhibitors.

CONCLUSIONS

Endothelial TRPV4 plays a key role in vascular permeability and lung inflammation following IR. TRPV4 channels may be a promising therapeutic target to mitigate lung IRI and decrease the incidence of primary graft dysfunction following transplant. (Word Count: 249/250).

HOTAIR/miR-17-5p Axis is Involved in the Propofol-Mediated Cardioprotection Against Ischemia/Reperfusion Injury

Background

Propofol (PPF) ameliorates ischemia/reperfusion (I/R) injury in multiple organs by reducing apoptosis and release of pro-inflammatory cytokines. This study aims to explore the mechanism of PPF in attenuating myocardial ischemia-reperfusion injury (MIRI).

Materials and Methods

Rat MIRI model was established, and PPF pre-treatment was performed 10 min before I/R. H9c2 cardiomyocytes treated with hypoxia/reoxygenation (H/R) were used to establish an in vitro model. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to evaluate HOTAIR and miR-17-5p expression levels. Flow cytometry was employed to detect the apoptosis of H9c2 cells. The interaction between HOTAIR and miR-17-5p was determined by bioinformatics analysis, luciferase reporter gene analysis, and RNA immunoprecipitation experiments. STAT3 and p-STAT3 expressions were detected by Western blot.

Results

PPF pre-treatment significantly reduced creatine kinase isoenzyme (CK-MB) and serum lactate dehydrogenase (LDH) levels in the serum of the rats with MIRI. PPF pre-treatment remarkably up-regulated HOTAIR expression and down-regulated miR-17-5p expression in both in vivo and in vitro models. HOTAIR adsorbed miR-17-5p to repress the expression of miR-17-5p. PPF pre-treatment markedly inhibited cardiomyocyte apoptosis induced by I/R or H/R. HOTAIR knockdown could partially reverse the protective effects of PPF on MIRI. HOTAIR could activate STAT3 signaling via repressing miR-17-5p expression.

Conclusion

PPF protects the MIRI by modulating the HOTAIR/miR-17-5p/STAT3 axis.

Role of the purinergic signaling network in lung ischemia-reperfusion injury

PURPOSE OF REVIEW

Primary graft dysfunction (PGD) is the leading cause of early mortality following lung transplantation and is typically caused by lung ischemia-reperfusion injury (IRI). Current management of PGD is largely supportive and there are no approved therapies to prevent lung IRI after transplantation. The purinergic signaling network plays an important role in this sterile inflammatory process, and pharmacologic manipulation of said network is a promising therapeutic strategy. This review will summarize recent findings in this area.

RECENT FINDINGS

In the past 18 months, our understanding of lung IRI has improved, and it is becoming clear that the purinergic signaling network plays a vital role. Recent works have identified critical components of the purinergic signaling network (Pannexin-1 channels, ectonucleotidases, purinergic P1 and P2 receptors) involved in inflammation in a number of pathologic states including lung IRI. In addition, a functionally-related calcium channel, the transient receptor potential vanilloid type 4 (TRPV4) channel, has recently been linked to purinergic signaling and has also been shown to mediate lung IRI.

SUMMARY

Agents targeting components of the purinergic signaling network are promising potential therapeutics to limit inflammation associated with lung IRI and thus decrease the risk of developing PGD.

Pharmacological Conditioning of the Heart: An Update on Experimental Developments and Clinical Implications

The aim of pharmacological conditioning is to protect the heart against myocardial ischemia-reperfusion (I/R) injury and its consequences. There is extensive literature that reports a multitude of different cardioprotective signaling molecules and mechanisms in diverse experimental protocols. Several pharmacological agents have been evaluated in terms of myocardial I/R injury. While results from experimental studies are immensely encouraging, translation into the clinical setting remains unsatisfactory. This narrative review wants to focus on two aspects: (1) give a comprehensive update on new developments of pharmacological conditioning in the experimental setting concentrating on recent literature of the last two years and (2) briefly summarize clinical evidence of these cardioprotective substances in the perioperative setting highlighting their clinical implications. By directly opposing each pharmacological agent regarding its recent experimental knowledge and most important available clinical data, a clear overview is given demonstrating the remaining gap between basic research and clinical practice. Finally, future perspectives are given on how we might overcome the limited translatability in the field of pharmacological conditioning.

[Perioperative cardioprotection - From bench to bedside : Current experimental evidence and possible reasons for the limited translation into the clinical setting]

Hintergrund

Ziel der perioperativen Kardioprotektion ist es, die Auswirkungen eines Ischämie- und Reperfusionsschadens zu minimieren. Aus anästhesiologischer Sicht spielt dieser Aspekt insbesondere in der Herzchirurgie bei Patienten mit Einsatz der Herz-Lungen-Maschine, aber auch allgemein bei längerfristigen hypotensiven Phasen oder perioperativen ischämischen Ereignissen im nichtkardiochirurgischen Setting eine wichtige Rolle. Im Laufe der letzten Jahre konnten diverse pharmakologische sowie nichtpharmakologische Strategien der Kardioprotektion identifiziert werden. Die Ergebnisse von Studien an isoliertem Gewebe sowie von tierexperimentellen In-vivo-Studien sind vielversprechend. Eine Translation dieser kardioprotektiven Strategien in die klinische Praxis ist bislang jedoch nicht gelungen. Große klinische Studien konnten keine signifikante Verbesserung des Outcome der Patienten zeigen.

Ziel der Arbeit

Dieser Übersichtsartikel gibt einen Überblick über die aktuelle experimentelle Evidenz pharmakologischer und nichtpharmakologischer Kardioprotektion. Außerdem sollen mögliche Gründe für die limitierte Translation diskutiert werden. Schließlich werden Möglichkeiten aufgezeigt, wie der Schritt „from bench to bedside“ in Zukunft doch noch gelingen könnte.

Material und Methoden

Narrative Übersichtsarbeit.

Ergebnisse und Diskussion

Trotz der vielversprechenden präklinischen experimentellen Ansätze zum Thema Kardioprotektion besteht nach wie vor eine große Diskrepanz zu den Ergebnissen aus großen klinischen Studien in der perioperativen Phase. Mögliche Gründe für die limitierte Translation könnten insbesondere Komorbiditäten und Komedikationen, die Wahl des Anästhesieverfahrens, aber auch die Wahl des Studiendesigns sein. Eine sorgfältige Studienplanung mit Berücksichtigung der genannten Probleme sowie ein simultaner Einsatz mehrerer kardioprotektiver Strategien mit dem Ziel eines additiven bzw. synergistischen Effekts stellen mögliche Ansätze für die Zukunft dar.

Perioperative Cardioprotection: General Mechanisms and Pharmacological Approaches

Cardioprotection encompasses a variety of strategies protecting the heart against myocardial injury that occurs during and after inadequate blood supply to the heart during myocardial infarction. While restoring reperfusion is crucial for salvaging myocardium from further damage, paradoxically, it itself accounts for additional cell death-a phenomenon named ischemia/reperfusion injury. Therefore, therapeutic strategies are necessary to render the heart protected against myocardial infarction. Ischemic pre- and postconditioning, by short periods of sublethal cardiac ischemia and reperfusion, are still the strongest mechanisms to achieve cardioprotection. However, it is highly impractical and far too invasive for clinical use. Fortunately, it can be mimicked pharmacologically, for example, by volatile anesthetics, noble gases, opioids, propofol, dexmedetomidine, and phosphodiesterase inhibitors. These substances are all routinely used in the clinical setting and seem promising candidates for successful translation of cardioprotection from experimental protocols to clinical trials. This review presents the fundamental mechanisms of conditioning strategies and provides an overview of the most recent and relevant findings on different concepts achieving cardioprotection in the experimental setting, specifically emphasizing pharmacological approaches in the perioperative context.

Ischemia Reperfusion Injury: Opportunities for Nanoparticles

Ischemia reperfusion (IR)-induced oxidative stress, accompanied by inflammatory responses, contributes to morbidity and mortality in numerous diseases such as acute coronary syndrome, stroke, organ transplantation, and limb injury. Ischemia results in profound hypoxia and tissue dysfunction, whereas subsequent reperfusion further aggravates ischemic tissue damage through inducing cell death and activating inflammatory responses. In this review, we highlight recent studies of therapeutic strategies against IR injury. Furthermore, nanotechnology offers significant improvements in this area. Hence, we also review recent advances in nanomedicines for IR therapy, suggesting them as potent and promising strategies to improve drug delivery to IR-injured tissues and achieve protective effects.

Adipose-derived exosomes protect the pulmonary endothelial barrier in ventilator-induced lung injury by inhibiting the TRPV4/Ca2+ signaling pathway

Mechanical ventilation (MV) is the main supportive treatment of acute respiratory distress syndrome (ARDS), but it may lead to ventilator-induced lung injury (VILI). Large epidemiological studies have found that obesity was associated with lower mortality in mechanically ventilated patients with acute lung injury, which is known as “obesity paradox.” However, the effects of obesity on VILI are unknown. In the present study, wild-type mice were fed a high-fat diet (HFD) and ventilated with high tidal volume to investigate the effects of obesity on VILI in vivo, and pulmonary microvascular endothelial cells (PMVECs) were subjected to 18% cyclic stretching (CS) to further investigate its underlying mechanism in vitro. We found that HFD protects mice from VILI by alleviating the pulmonary endothelial barrier injury and inflammatory responses in mice. Adipose-derived exosomes can regulate distant tissues as novel adipokines, providing a new mechanism for cell-cell interactions. We extracted three adipose-derived exosomes, including HFD mouse serum exosome (S-Exo), adipose tissue exosome (AT-Exo), and adipose-derived stem cell exosome (ADSC-Exo), and further explored their effects on MV or 18% CS-induced VILI in vivo and in vitro. Administration of three exosomes protected against VILI by suppressing pulmonary endothelial barrier hyperpermeability, repairing the expression of adherens junctions, and alleviating inflammatory response in vivo and in vitro, accompanied by transient receptor potential vanilloid 4 (TRPV4)/Ca²⁺ pathway inhibition. Collectively, these data indicated that HFD-induced obesity plays a protective role in VILI by alleviating the pulmonary endothelial barrier injury and inflammatory response via adipose-derived exosomes, at least partially, through inhibiting the TRPV4/Ca²⁺ pathway.