Mitochondrial injury underlies hyporeactivity of arterial smooth muscle in severe shock

Frequency-dependent changes in mitochondrial number and generation of reactive oxygen species in a rat model of vibration-induced injury

Regular use of vibrating hand tools results in cold-induced vasoconstriction, finger blanching, and a reduction in tactile sensitivity and manual dexterity. Depending upon the length and frequency, vibration induces regeneration, or dysfunction and apoptosis, inflammation and an increase in reactive oxygen species (ROS) levels. These changes may be associated with mitochondria, this study examined the effects of vibration on total and functional mitochondria number. Male rats were exposed to restraint or tail vibration at 62.5, 125, or 250 Hz. The frequency-dependent effects of vibration on mitochondrial number and generation of oxidative stress were examined. After 10 days of exposure at 125 Hz, ventral tail arteries (VTA) were constricted and there was an increase in mitochondrial number and intensity of ROS staining. In the skin, the influence of vibration on arterioles displayed a similar but insignificant response in VTA. There was also a reduction in the number of small nerves with exposure to vibration at 250 Hz, and a reduction in mitochondrial number in nerves in restrained and all vibrated conditions. There was a significant rise in the size of the sensory receptors with vibration at 125 Hz, and an elevation in ROS levels. Based upon these results, mitochondria number and activity are affected by vibration, especially at frequencies at or near resonance. The influence of vibration on the vascular system may either be adaptive or maladaptive. However, the effects on cutaneous nerves might be a precursor to loss of innervation and sensory function noted in workers exposed to vibration.

Dengue Virus Infection of Primary Human Smooth Muscle Cells

Dengue virus (DENV) infection of humans is presently the most important arthropod-borne viral global threat, for which no suitable or reliable animal model exists. Reports addressing the effect of DENV on vascular components other than endothelial cells are lacking. Dengue virus infection of vascular smooth muscle cells, which play a physiological compensatory response to hypotension in arteries and arterioles, has not been characterized, thus precluding our understanding of the role of these vascular components in dengue pathogenesis. Therefore, we studied the permissiveness of primary human umbilical artery smooth muscle cells (HUASMC) to DENV 1-4 infection and compared with the infection in the previously reported primary human umbilical vein endothelial cells (HUVEC) and the classically used, non-transformed, and highly permissive Lilly Laboratories Cell-Monkey Kidney 2 cells. Our results show that HUASMC are susceptible and productive to infection with the four DENV serotypes, although to a lesser extent when compared with the other cell lines. This is the first report of DENV permissiveness in human smooth muscle cells, which might represent an unexplored pathophysiological contributor to the vascular collapse observed in severe human dengue infection.

Polydatin prevents the induction of secondary brain injury after traumatic brain injury by protecting neuronal mitochondria

Polydatin is thought to protect mitochondria in different cell types in various diseases. Mitochondrial dysfunction is a major contributing factor in secondary brain injury resulting from traumatic brain injury. To investigate the protective effect of polydatin after traumatic brain injury, a rat brain injury model of lateral fluid percussion was established to mimic traumatic brain injury insults. Rat models were intraperitoneally injected with polydatin (30 mg/kg) or the SIRT1 activator SRT1720 (20 mg/kg, as a positive control to polydatin). At 6 hours post-traumatic brain injury insults, western blot assay was used to detect the expression of SIRT1, endoplasmic reticulum stress related proteins and p38 phosphorylation in cerebral cortex on the injured side. Flow cytometry was used to analyze neuronal mitochondrial superoxide, mitochondrial membrane potential and mitochondrial permeability transition pore opened. Ultrastructural damage in neuronal mitochondria was measured by transmission electron microscopy. Our results showed that after treatment with polydatin, release of reactive oxygen species in neuronal mitochondria was markedly reduced; swelling of mitochondria was alleviated; mitochondrial membrane potential was maintained; mitochondrial permeability transition pore opened. Also endoplasmic reticulum stress related proteins were inhibited, including the activation of p-PERK, spliced XBP-1 and cleaved ATF6. SIRT1 expression and activity were increased; p38 phosphorylation and cleaved caspase-9/3 activation were inhibited. Neurological scores of treated rats were increased and the mortality was reduced compared with the rats only subjected to traumatic brain injury. These results indicated that polydatin protectrd rats from the consequences of traumatic brain injury and exerted a protective effect on neuronal mitochondria. The mechanisms may be linked to increased SIRT1 expression and activity, which inhibits the p38 phosphorylation-mediated mitochondrial apoptotic pathway. This study was approved by the Animal Care and Use Committee of the Southern Medical University, China (approval number: L2016113) on January 1, 2016.

Heller A, Sabashnikov A, Teske W. The Nomenclature, Definition and Distinction of Types of Shock

BACKGROUND

A severe mismatch between the supply and demand of oxygen is the common feature of all types of shock. We present a newly developed, clinically oriented classification of the various types of shock and their therapeutic implications.

METHODS

This review is based on pertinent publications (1990-2018) retrieved by a selective search in PubMed, and on the relevant guidelines and meta-analyses.

RESULTS

There are only four major categories of shock, each of which is mainly related to one of four organ systems. Hypovolemic shock relates to the blood and fluids compartment while distributive shock relates to the vascular system; cardiogenic shock arises from primary cardiac dysfunction; and obstructive shock arises from a blockage of the circulation. Hypovolemic shock is due to intravascular volume loss and is treated by fluid replacement with balanced crystalloids. Distributive shock, on the other hand, is a state of relative hypovolemia resulting from pathological redistribution of the absolute intravascular volume and is treated with a combination of vasoconstrictors and fluid replacement. Cardiogenic shock is due to inadequate function of the heart, which shall be treated, depending on the situation, with drugs, surgery, or other interventional procedures. In obstructive shock, hypoperfusion due to elevated resistance shall be treated with an immediate life-saving intervention.

CONCLUSION

The new classification is intended to facilitate the goal-driven treatment of shock in both the pre-hospital and the inpatient setting. A uniform treatment strategy should be established for each of the four types of shock.

Activation of sirtuin 1/3 improves vascular hyporeactivity in severe hemorrhagic shock by alleviation of mitochondrial damage

Vascular hyporeactivity is one of the major causes responsible for refractory hypotension and associated mortality in severe hemorrhagic shock. Mitochondrial permeability transition (mPT) pore opening in arteriolar smooth muscle cells (ASMCs) is involved in the pathogenesis of vascular hyporeactivity. However, the molecular mechanism underlying mitochondrial injury in ASMCs during hemorrhagic shock is not well understood. Here we produced an in vivo model of severe hemorrhagic shock in adult Wistar rats. We found that sirtuin (SIRT)1/3 protein levels and deacetylase activities were decreased in ASMCs following severe shock. Immunofluorescence staining confirmed reduced levels of SIRT1 in the nucleus and SIRT3 in the mitochondria, respectively. Acetylation of cyclophilin D (CyPD), a component of mPT pore, was increased. SIRT1 activators suppressed mPT pore opening and ameliorated mitochondrial injury in ASMCs after severe shock. Furthermore, administration of SIRT1 activators improved vasoreactivity in rats under severe shock. Our data suggest that epigenetic mechanisms, namely histone post-translational modifications, are involved in regulation of mPT by SIRT1/SIRT3- mediated deacetylation of CyPD. SIRT1/3 is a promising therapeutic target for the treatment of severe hemorrhagic shock.

Polydatin protects hepatocytes against mitochondrial injury in acute severe hemorrhagic shock via SIRT1-SOD2 pathway

OBJECTIVE

The aim of the study was to determine whether hepatocyte mitochondrial injury instigates severe shock and to explore effective therapy.

METHODS

Wistar rats were randomly divided into five groups: Control (sham) group, shock + normal saline, shock + cyclosporine A, shock + resveratrol (Res) and shock + polydatin (PD) group. Mitochondrial morphology and function in hepatocytes following treatment were determined.

RESULTS

Hepatocytes following severe shock exhibited mitochondrial dysfunction characterized with opening of mitochondrial permeability transition pores, mitochondrial swelling, decreased mitochondrial membrane potential (ΔΨm) and reduced ATP levels. Moreover, severe shock induced oxidative stress with increased lipid peroxidation and reactive oxygen species, decreased SOD2 (Superoxide Dismutase 2) and GSH/GSSG, which resulted in increased lysosomal membrane permeabilization and hepatocyte mitochondrial injury. Additionally, Res and PD restored decreased deacetylase sirtuin1 activity and protein expression in liver tissue following severe shock, suppressed oxidative stress-induced lysosomal unstability and mitochondrial injury by increasing the protein expression of SOD2, and thereby contributed to the prevention of hepatocyte mitochondria dysfunction and liver injury.

CONCLUSIONS

PD effectively preserved hepatocytes from mitochondrial injury via SIRT1-SOD2 pathway and may be a new approach to treatment of irreversible shock.

Polydatin: a new therapeutic agent against multiorgan dysfunction

BACKGROUND

Polydatin (PD), a monocrystalline and polyphenolic drug isolated from a traditional Chinese herb (Polygonum cuspidatum), is protective against mitochondrial dysfunction and has been approved for clinical trials in the treatment of shock. However, whether the administration of PD has a therapeutic effect on multiple-organ dysfunction syndrome (MODS) requires investigation.

MATERIAL AND METHODS

MODS was induced in Sprague-Dawley rats via hemorrhage and ligation and puncture of cecum-induced sepsis. The rats were divided into three groups as follows: MODS + PD, MODS + normal saline, and a control group (no treatment). Survival time, blood biochemical indexes, and histopathologic changes in various organs were evaluated; serum oxidative stress (advanced oxidative protein products [AOPPs]) and proinflammatory cytokines (tumor necrosis factor-α, interleukin 1β, and interleukin 6) were assayed using enzyme-linked immunosorbent assay. Apoptosis-related protein expression (B-cell lymphoma-2 [Bcl-2] and Bax) was assayed by immunohistochemical and Western blotting methods, whereas caspase-3 activity was assayed by spectrophotometry.

RESULTS

PD improved organ function, prolonged survival time, and reduced MODS incidence and serum levels of AOPPs and proinflammatory cytokines. It also decreased Bax levels and caspase-3 activity and increased Bcl-2 levels in the kidney and liver.

CONCLUSIONS

PD may serve as a potential therapeutic for MODS, as it suppresses oxidative stress, inhibits inflammatory response, attenuates apoptosis, and protects against mitochondrial dysfunction.

Norepinephrine Decreases Fluid Requirements and Blood Loss While Preserving Intestinal Villi Microcirculation during Fluid Resuscitation of Uncontrolled Hemorrhagic Shock in Mice

Background:

Norepinephrine administration is controversial during hemorrhagic shock resuscitation to stabilize mean arterial pressure (MAP) level because it could have deleterious effects on local circulations. The authors investigated the effect of norepinephrine on intestinal microcirculation during fluid resuscitation in uncontrolled hemorrhagic shock.

Methods:

Mice (n = 6 per group) submitted to an uncontrolled hemorrhagic shock by tail section were randomly assigned to a resuscitation with fluid but without norepinephrine to target a MAP level of 50 mmHg (FR50) or 60 mmHg (FR60) or a resuscitation with fluid and norepinephrine to target a MAP level of 50 mmHg (FRNE50) or 60 mmHg (FRNE60). Intestinal microcirculation was observed by intravital microscopy.

Results:

Fluid requirements were lower in groups resuscitated with fluid and norepinephrine than in groups resuscitated with fluid without norepinephrine (74.6 ± 45.1 in FR50vs. 28.1 ± 10.0 µl/g in FRNE50; P = 0.004 and 161.9 ± 90.4 in FR60vs. 44.5 ± 24.0 µl/g in FRNE60; P = 0.041). Blood loss was not statistically different between FR50 and FRNE50 (14.8 ± 8.3 vs. 8.5 ± 2.9 µl/g; P = 0.180) but was significantly lower in FRNE60 than in FR60 (10.1 ± 4.2 vs. 22.6 ± 9.6 µl/g; P = 0.015). This beneficial effect was associated with the restoration of intestinal microcirculation to the same extent in fluid resuscitated groups without norepinephrine (FR50 and FR60) and fluid resuscitated groups with norepinephrine (FRNE50 and FRNE60).

Conclusions:

During MAP-directed resuscitation of uncontrolled hemorrhagic shock, the administration of norepinephrine decreased blood loss and fluid requirements while preserving intestinal villi microcirculation.

Propofol inhibits burn injury-induced hyperpermeability through an apoptotic signal pathway in microvascular endothelial cells

Recent studies have revealed that an intrinsic apoptotic signaling cascade is involved in vascular hyperpermeability and endothelial barrier dysfunction. Propofol (2,6-diisopropylphenol) has also been reported to inhibit apoptotic signaling by regulating mitochondrial permeability transition pore (mPTP) opening and caspase-3 activation. Here, we investigated whether propofol could alleviate burn serum-induced endothelial hyperpermeability through the inhibition of the intrinsic apoptotic signaling cascade. Rat lung microvascular endothelial cells (RLMVECs) were pretreated with propofol at various concentrations, followed by stimulation with burn serum, obtained from burn-injury rats. Monolayer permeability was determined by transendothelial electrical resistance. Mitochondrial release of cytochrome C was measured by ELISA. Bax and Bcl-2 expression and mitochondrial release of second mitochondrial-derived activator of caspases (smac) were detected by Western blotting. Caspase-3 activity was assessed by fluorometric assay; mitochondrial membrane potential (Δψm) was determined with JC-1 (a potential-sensitive fluorescent dye). Intracellular ATP content was assayed using a commercial kit, and reactive oxygen species (ROS) were measured by dichlorodihydrofluorescein diacetate (DCFH-DA). Burn serum significantly increased monolayer permeability (P<0.05), and this effect could be inhibited by propofol (P<0.05). Compared with a sham treatment group, intrinsic apoptotic signaling activation - indicated by Bax overexpression, Bcl-2 downregulation, Δψm reduction, decreased intracellular ATP level, increased cytosolic cytochrome C and smac, and caspase-3 activation - was observed in the vehicle group. Propofol not only attenuated these alterations (P<0.05 for all), but also significantly decreased burn-induced ROS production (P<0.05). Propofol attenuated burn-induced RLMVEC monolayer hyperpermeability by regulating the intrinsic apoptotic signaling pathway.

Mesenteric lymph duct ligation after hemorrhagic shock enhances the ATP level and ATPase activity in rat kidneys

BACKGROUND

Kidney injury commonly occurs following hemorrhagic shock. This study aims to observe the effects of mesenteric lymph duct ligation (MLDL) on the adenosine triphosphate (ATP) levels and the cell membrane adenosine triphosphatase (ATPase) activity in the kidneys of rats subjected to hemorrhagic shock.

METHODS

Wistar rats were assigned into sham, shock, and ligation groups. The hemorrhagic shock model was established in the shock and ligation groups, and MLDL was performed in the ligation group after resuscitation. Renal homogenates were prepared to determine the ATP and ATPase levels at 90 min after hemorrhage and at 0, 1, 3, 6, 12, and 24 h after resuscitation.

RESULTS

The ATP levels, and the Na(+)-K(+)-ATPase, Mg(2+)-ATPase, Ca(2+)-ATPase, and Ca(2+)-Mg(2+)-ATPase activities in the renal tissue of the shock group were lower than those in the sham group at the multiple time points. Furthermore, the corresponding values in the ligation group were significantly higher than those in the shock group at multiple time points.

CONCLUSION

MLDL improves energy metabolism and enhances the ATPase activity in the kidneys of hemorrhagic shock rats, along with other mechanisms that alleviate renal injury after hemorrhagic shock.

Cerebral hemodynamic change and metabolic alteration in severe hemorrhagic shock

Understanding the biological mechanism and identifying biomarkers of hemorrhagic shock is important for diagnosis and treatment. We aim to use optical imaging to study how the cerebral blood circulation and metabolism change during the progression of severe hemorrhagic shock, especially the decompensatory stage. We used a multi-parameter (blood pressure (BP), cerebral blood flow (CBF), functional vascular density (FVD), blood oxygenation and mitochondrial NADH signal) cerebral cortex optical imaging system to observe brain hemodynamic change and metabolic alteration of rats in vivo for 4 h. Cerebral circulation and mitochondrial metabolism could be well preserved in the compensatory stage but impaired during the decompensatory stage. The changes of brain hemodynamics and metabolism may provide sensitive indicators for various shock stages including the transition from compensatory stage to decompensatory stage. Our novel imaging observations of hemodynamic and metabolic signals in vivo indicated that the rat brains under hemorrhagic shock suffered irreversible damage which could not be compensated by the autoregulation mechanism, probably due to injured mitochondria.

Rap1 ameliorates renal tubular injury in diabetic nephropathy

Rap1b ameliorates high glucose (HG)-induced mitochondrial dysfunction in tubular cells. However, its role and precise mechanism in diabetic nephropathy (DN) in vivo remain unclear. We hypothesize that Rap1 plays a protective role in tubular damage of DN by modulating primarily the mitochondria-derived oxidative stress. The role and precise mechanisms of Rap1b on mitochondrial dysfunction and of tubular cells in DN were examined in rats with streptozotocin (STZ)-induced diabetes that have Rap1b gene transfer using an ultrasound microbubble-mediated technique as well as in renal proximal epithelial tubular cell line (HK-2) exposed to HG ambiance. The results showed that Rap1b expression decreased significantly in tubules of renal biopsies from patients with DN. Overexpression of a constitutively active Rap1b G12V notably ameliorated renal tubular mitochondrial dysfunction, oxidative stress, and apoptosis in the kidneys of STZ-induced rats, which was accompanied with increased expression of transcription factor C/EBP-β and PGC-1α. Furthermore, Rap1b G12V also decreased phosphorylation of Drp-1, a key mitochondrial fission protein, while boosting the expression of genes related to mitochondrial biogenesis and antioxidants in HK-2 cells induced by HG. These effects were imitated by transfection with C/EBP-β or PGC-1α short interfering RNA. In addition, Rap1b could modulate C/EBP-β binding to the endogenous PGC-1α promoter and the interaction between PGC-1α and catalase or mitochondrial superoxide dismutase, indicating that Rap1b ameliorates tubular injury and slows the progression of DN by modulation of mitochondrial dysfunction via C/EBP-β-PGC-1α signaling.

Monitoring hemodynamic and metabolic alterations during severe hemorrhagic shock in rat brains

RATIONALE AND OBJECTIVES

Our long-term goals are to identify imaging biomarkers for hemorrhagic shock and to understand how the preservation of cerebral microcirculation works. We also seek to understand how the damage occurs to the cerebral hemodynamics and the mitochondrial metabolism during severe hemorrhagic shock.

MATERIALS AND METHODS

We used a multimodal cerebral cortex optical imaging system to obtain 4-hour observations of cerebral hemodynamic and metabolic alterations in exposed rat cortexes during severe hemorrhagic shock. We monitored the mean arterial pressure, heart rate, cerebral blood flow (CBF), functional vascular density (FVD), vascular perfusion and diameter, blood oxygenation, and mitochondrial reduced nicotinamide adenine dinucleotide (NADH) signals.

RESULTS

During the rapid bleeding and compensatory stage, cerebral parenchymal circulation was protected by inhibiting the perfusion of dural vessels. During the compensatory stage, although the brain parenchymal CBF and FVD decreased rapidly, the NADH signal did not show a significant increase. During the decompensatory stage, FVD and CBF maintained the same low level and the NADH signal remained unchanged. However, the NADH signal showed a significant increase after the rapid blood infusion. FVD and CBF rebounded to the baseline after the resuscitation and then declined again.

CONCLUSIONS

We present for the first time simultaneous imaging of cerebral hemodynamics and NADH signals in vivo during the process of hemorrhagic shock. This novel multimodal method demonstrated clearly that severe hemorrhagic shock imparts irreversible tissue damage that is not compensated by the autoregulatory mechanism. Hemodynamic and metabolic signatures including CBF, FVD, and NADH may be further developed to provide sensitive biomarkers for stage transitions in hemorrhagic shock.

Polydatin, a natural polyphenol, protects arterial smooth muscle cells against mitochondrial dysfunction and lysosomal destabilization following hemorrhagic shock

The main objective of this study was to investigate the activity of polydatin on mitochondrial dysfunction and lysosomal stability of arteriolar smooth muscle cells (ASMCs) in severe shock. The experimental animals (rats) were divided into five groups: control, hemorrhagic shock, shock + CsA, shock + Res, and shock + PD (exposed to cyclosporin A, resveratrol, or polydatin following induction of hemorrhagic shock, respectively). The calcein-Co(2+) technique revealed opening of ASMC mitochondrial permeability transition pores (mPTP) after shock with resulting mitochondrial swelling, decreased mitochondrial membrane potential (ΔΨm), and reduced intracellular ATP levels. These alterations were all inhibited by exposure to PD, which was significantly more effective than CsA and Res. PD also preserved lysosomal stability, suppressed activation of K(ATP) channels, ASMC hyperpolarization, and reduced vasoresponsiveness to norepinephrine that normally follows severe shock. The results demonstrate that exposure to PD after initiation of severe shock effectively preserves ASMC mitochondrial integrity and has a significant therapeutic effect in severe shock. The effects may partially result from lysosomal stabilization against shock-induced oxidative stress and depressed relocation of hydrolytic enzymes and redox-active lysosomal iron that, in turn, may induce mPTP opening.