Effects of inhalation of low-dose nitrite or carbon monoxide on post-reperfusion mitochondrial function and tissue injury in hemorrhagic shock swine

Inhibition of miR-142-3p promotes intestinal epithelial proliferation and barrier function after ischemia/reperfusion injury by targeting FoxM1

Damage of intestinal barrier function (BF) after ischemia/reperfusion (I/R) injury can induce serious complications and high mortality. MicroRNAs (miRNAs) are involved in intestinal mucosal BF and epithelial proliferation after I/R injury have been reported. We aimed to investigate the role and regulatory mechanism of miR-142-3p (miR-142) in intestinal epithelial proliferation and BF after I/R injury. We detected the proliferation, barrier function and miR-142 expression in clinical ischemic intestinal tissues. Furthermore, we induced an in vivo intestinal I/R injury mouse model and in vitro IEC-6 cells hypoxia/reoxygenation (H/R) injury model. After increasing and decreasing expression of miR-142, we detected the proliferation and barrier function of intestinal epithelial cells after I/R or H/R injury. We found that miR-142 expression was significantly increased in clinical ischemic intestinal mucosa and mouse intestinal mucosa exposed to I/R injury, and there was an inverse relationship between miR-142 and proliferation/BF. Inhibition of miR-142 significant promoted intestinal epithelial proliferation and BF after I/R injury. Furthermore, inhibition of miR-142 improved overall survival rate of mice after I/R injury. MiR-142 directly targeted FoxM1 which was identified by bioinformatics analysis and luciferase activity assay in IEC-6 cells. Inhibition of miR-142 promotes intestinal epithelial proliferation and BF after I/R injury in a FoxM1-mediated manner.

Autonomous precision resuscitation during ground and air transport of an animal hemorrhagic shock model

We tested the ability of a physiologically driven minimally invasive closed-loop algorithm, called Resuscitation based on Functional Hemodynamic Monitoring (ReFit), to stabilize for up to 3 h a porcine model of noncompressible hemorrhage induced by severe liver injury and do so during both ground and air transport. Twelve animals were resuscitated using ReFit to drive fluid and vasopressor infusion to a mean arterial pressure (MAP) > 60 mmHg and heart rate < 110 min-1 30 min after MAP < 40 mmHg following liver injury. ReFit was initially validated in 8 animals in the laboratory, then in 4 animals during air (23nm and 35nm) and ground (9 mi) to air (9.5nm and 83m) transport returning to the laboratory. The ReFit algorithm kept all animals stable for ~ 3 h. Thus, ReFit algorithm can diagnose and treat ongoing hemorrhagic shock independent to the site of care or during transport. These results have implications for treatment of critically ill patients in remote, austere and contested environments and during transport to a higher level of care.

The Microcirculatory Response to Endotoxemia and Resuscitation Is a Marker of Regional Renal Perfusion, Renal Metabolic Stress, and Tubular Injury

Aims: We sought to investigate the relationship between macrohemodynamic resuscitation and microcirculatory parameters with the response of microcirculatory flow, tissue-specific parameters of metabolic stress and injury. We hypothesized that early resuscitation based on macrohemodynamic parameters does not prevent the development of organ dysfunction in a porcine model of endotoxemic shock, and that sublingual microcirculatory parameters are associated with markers of tissue metabolic stress and injury. Results: Both resuscitation groups had significant increases in creatinine and neutrophil gelatinase-associated lipocalin as compared with baseline. Neither the macrovascular response to endotoxemia or resuscitation, nor group allocation predicted the development of acute kidney injury (AKI). Only a microvascular flow index (MFI) <2.5 was associated with the development of renal tubular injury and AKI, and with increased renal, liver, peritoneal, and sublingual lactate/pyruvate (L/P) ratio and lactate. Among systemic parameters, only partial pressure of carbon dioxide (PCO₂) gap >6 and P(a-v)CO₂/C(v-a)O₂ >1.8 were associated with increased organ L/P ratio and AKI. Innovation and Conclusion: Our findings demonstrate that targeting macrohemodynamics to guide resuscitation during endotoxemic shock failed to predict tissue metabolic stress and the response of the microvasculature to resuscitation, and was unsuccessful in preventing tubular injury and AKI. Mechanistically, our data suggest that loss of hemodynamic coherence and decoupling of microvascular flow from tissue metabolic demand during endotoxemia may explain the lack of association between macrohemodynamics and perfusion goals. Finally, we demonstrate that MFI, PCO₂ gap, and P(v-a)CO₂/C(a-v)O₂ ratio outperformed macrohemodynamic parameters at predicting the development of renal metabolic stress and tubular injury, and therefore, that these indices merit further validation as promising resuscitation targets. Antioxid. Redox Signal. 35, 1407-1425.

Early detection of complications in pancreas transplants by microdialysis catheters, an observational feasibility study

Background

Despite advances in immunosuppression and surgical technique, pancreas transplantation is encumbered with a high rate of complication and graft losses. Particularly, venous graft thrombi occur relatively frequently and are rarely detected before the transplant is irreversibly damaged.

Methods

To detect complications early, when the grafts are potentially salvageable, we placed microdialysis catheters anteriorly and posteriorly to the graft in a cohort of 34 consecutive patients. Glucose, lactate, pyruvate, and glycerol were measured at the bedside every 1–2 hours.

Results

Nine patients with graft venous thrombosis had significant lactate and lactate–to-pyruvate-ratio increases without concomitant rise in blood glucose or clinical symptoms. The median lactate in these patients was significantly higher in both catheters compared to non-events (n = 15). Out of the nine thrombi, four grafts underwent successful angiographic extraction, one did not require intervention and four grafts were irreversibly damaged and explanted. Four patients with enteric anastomosis leakages had significantly higher glycerol measurements compared to non-events. As with the venous thrombi, lactate and lactate-to-pyruvate ratio were also increased in six patients with graft surrounding hematomas.

Conclusions

Bedside monitoring with microdialysis catheters is a promising surveillance modality of pancreatic grafts, but differentiating between the various pathologies proves challenging.

Nitric Oxide in Post-cardiac Arrest Syndrome

Sudden cardiac arrest is a leading cause of death worldwide. Although the methods of cardiopulmonary resuscitation have been improved, mortality is still unacceptably high, and many survivors suffer from lasting neurological deficits due to the post-cardiac arrest syndrome (PCAS). Pathophysiologically, generalized vascular endothelial dysfunction accompanied by platelet activation and systemic inflammation has been implicated in the pathogenesis of PCAS. Because endothelial-derived nitric oxide (NO) plays a central role in maintaining vascular homeostasis, the role of NO-dependent signaling has been a focus of the intense investigation. Recent preclinical studies showed that therapeutic interventions that increase vascular NO bioavailability may improve outcomes after cardiac arrest complicated with PCAS. In particular, NO inhalation therapy has been shown to improve neurological outcomes and survival in multiple species. Clinical studies examining the safety and efficacy of inhaled NO in patients sustaining PCAS are warranted.

Gasotransmitters in health and disease: a mitochondria-centered view

Gasotransmitters fulfill important roles in cellular homeostasis having been linked to various pathologies, including inflammation and cardiovascular diseases. In addition to the known pathways mediating the actions of gasotransmitters, their effects in regulating mitochondrial function are emerging. Given that mitochondria are key organelles in energy production, formation of reactive oxygen species and apoptosis, they are important mediators in preserving health and disease. Preserving or restoring mitochondrial function by gasotransmitters may be beneficial, and mitigate pathogenetic processes. In this review we discuss the actions of gasotransmitters with focus on their role in mitochondrial function and their therapeutic potential.

Mitochondrial Autophagy and NLRP3 Inflammasome in Pulmonary Tissues from Severe Combined Immunodeficient Mice after Cardiac Arrest and Cardiopulmonary Resuscitation

Background:

The incidence of cancer, diabetes, and autoimmune diseases has been increasing. Furthermore, there are more and more patients with solid organ transplants. The survival rate of these immunocompromised individuals is extremely low when they are severely hit-on. In this study, we established cardiac arrest cardiopulmonary resuscitation (CPR) model in severe combined immunodeficient (SCID) mice, analyzed the expression and activation of mitochondrial autophagy and NLRP3 inflammasome/caspase-1, and explored mitochondrial repair and inflammatory injury in immunodeficiency individual during systemic ischemia-reperfusion injury.

Methods:

A potassium chloride-induced cardiac arrest model was established in C57BL/6 and nonobese diabetic/SCID (NOD/SCID) mice. One hundred male C57BL/6 mice and 100 male NOD/SCID mice were randomly divided into five groups (control, 2 h post-CPR, 12 h post-CPR, 24 h post-CPR, and 48 h post-CPR). A temporal dynamic view of alveolar epithelial cells, macrophages, and neutrophils from bronchoalveolar lavage fluid (BALF) was obtained using Giemsa staining. Spatial characterization of phenotypic analysis of macrophages in the lung interstitial tissue was analyzed by flow cytometry. The morphological changes of mitochondria 48 h after CPR were studied by transmission electron microscopy and quantified according to the Flameng grading system. Western blotting analysis was used to detect the expression and activation of the markers of mitochondrial autophagy, NLRP3 inflammasome, and caspase-1.

Results:

(1) In NOD/SCID mice, macrophages were disintegrated in BALF, and many alveolar epithelial cells were shed at 48 h after resuscitation. Compared with C57BL/6 mice, the ratio of macrophages/total cells peaked at 12 h and was significantly higher in NOD/SCID mice (31.17 ± 4.13 vs. 49.69 ± 2.43, t = 14.46, P = 0.001). After 24 h, the results showed a downward trend. Furthermore, a large number of macrophages were disintegrated in the BALF. (2) Mitochondrial autophagy was present in both C57BL/6 and NOD/SCID mice after CPR, but it began late in the NOD/SCID mice. Compared with C57BL/6 mice, phos-ULK1 (Ser³²⁷) expression was significantly lower at 2 h and 12 h after CPR (2 h after CPR: 1.88 ± 0.36 vs. 1.12 ± 0.11, t = −1.36, P < 0.01 and 12 h after CPR: 1.52 ± 0.16 vs. 1.05 ± 0.12, t = −0.33, P < 0.01), whereas phos-ULK1 (Ser⁷⁵⁷) expression was significantly higher at 2 h and 12 h after CPR in NOD/SCID mice (2 h after CPR: 1.28 ± 0.12 vs. 1.69 ± 0.14, t = 1.7, P < 0.01 and 12 h after CPR: 1.33 ± 0.10 vs. 1.94 ± 0.13, t = 2.75, P < 0.01). (3) Furthermore, NLRP3 inflammasome/caspase-1 activation in the pulmonary tissues occurred early and for only a short time in C57BL/6 mice, but this phenomenon was sustained in NOD/SCID mice. The expression of the NLRP3 inflammasome increased modestly in the C57 mice, but the increase was higher in the NOD/SCID mice than in the C57BL/6 mice, especially at 12, 24, 48 h after CPR (48 h after CPR: 1.46 ± 0.13 vs. 2.97 ± 0.19, t = 5.34, P = 0.001). The expression of caspase-1-20 generally followed the same pattern as the NLRP3 inflammasome.

Conclusions:

There is a regulatory relationship between the NLRP3 inflammasome and mitochondrial autophagy after CPR in the healthy mice. This regulatory relationship was disturbed in the NOD/SCID mice because the signals for mitochondrial autophagy occurred late, and NLRP3 inflammasome- and caspase-1-dependent cell injury was sustained.

Hemorrhagic Shock and the Microvasculature

The microvasculature plays a central role in the pathophysiology of hemorrhagic shock and is also involved in arguably all therapeutic attempts to reverse or minimize the adverse consequences of shock. Microvascular studies specific to hemorrhagic shock were reviewed and broadly grouped depending on whether data were obtained on animal or human subjects. Dedicated sections were assigned to microcirculatory changes in specific organs, and major categories of pathophysiological alterations and mechanisms such as oxygen distribution, ischemia, inflammation, glycocalyx changes, vasomotion, endothelial dysfunction, and coagulopathy as well as biomarkers and some therapeutic strategies. Innovative experimental methods were also reviewed for quantitative microcirculatory assessment as it pertains to changes during hemorrhagic shock. The text and figures include representative quantitative microvascular data obtained in various organs and tissues such as skin, muscle, lung, liver, brain, heart, kidney, pancreas, intestines, and mesentery from various species including mice, rats, hamsters, sheep, swine, bats, and humans. Based on reviewed findings, a new integrative conceptual model is presented that includes about 100 systemic and local factors linked to microvessels in hemorrhagic shock. The combination of systemic measures with the understanding of these processes at the microvascular level is fundamental to further develop targeted and personalized interventions that will reduce tissue injury, organ dysfunction, and ultimately mortality due to hemorrhagic shock. Published 2018. Compr Physiol 8:61-101, 2018.

Gaseous Mediators and Mitochondrial Function: The Future of Pharmacologically Induced Suspended Animation?

The role of nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H₂S) as poisonous gases is well-established. However, they are not only endogenously produced but also, at low concentrations, exert beneficial effects, such as anti-inflammation, and cytoprotection. This knowledge initiated the ongoing debate, as to whether these molecules, also referred to as “gaseous mediators” or “gasotransmitters,” could serve as novel therapeutic agents. In this context, it is noteworthy, that all gasotransmitters specifically target the mitochondria, and that this interaction may modulate mitochondrial bioenergetics, thereby subsequently affecting metabolic function. This feature is of crucial interest for the possible induction of “suspended animation.” Suspended animation, similar to mammalian hibernation (and/or estivation), refers to an externally induced hypometabolic state, with the intention to preserve organ function in order to survive otherwise life-threatening conditions. This hypometabolic state is usually linked to therapeutic hypothermia, which, however, comes along with adverse effects (e.g., coagulopathy, impaired host defense). Therefore, inducing an on-demand hypometabolic state by directly lowering the energy metabolism would be an attractive alternative. Theoretically, gasotransmitters should reversibly interact and inhibit the mitochondrial respiratory chain during pharmacologically induced suspended animation. However, it has to be kept in mind that this effect also bears the risk of cytotoxicity resulting from the blockade of the mitochondrial respiratory chain. Therefore, this review summarizes the current knowledge of the impact of gasotransmitters on modulating mitochondrial function. Further, we will discuss their role as potential candidates in inducing a suspended animation.

N-Nitrosamine-{cis-Re[CO]2}2+ cobalamin conjugates as mixed CO/NO-releasing molecules

Mixed CO/NO-releasing molecules were prepared by conjugation of the 17-electron rhenium dicarbonyl cis-[Re(CO)₂Br₄]²⁻ complex to N-nitrosamine modified cyanocobalamin (B12) bio-vectors.