Dose-related effects of dexmedetomidine on immunomodulation and mortality to septic shock in rats

Insight into Cardioprotective Effects and Mechanisms of Dexmedetomidine

PURPOSE

Cardiovascular disease remains the leading cause of death worldwide. Dexmedetomidine is a highly selective α2 adrenergic receptor agonist with sedative, analgesic, anxiolytic, and sympatholytic properties, and several studies have shown its possible protective effects in cardiac injury. The aim of this review is to further elucidate the underlying cardioprotective mechanisms of dexmedetomidine, thus suggesting its potential in the clinical management of cardiac injury.

RESULTS AND CONCLUSION

Our review summarizes the findings related to the involvement of dexmedetomidine in cardiac injury and discusses the results in the light of different mechanisms. We found that numerous mechanisms may contribute to the cardioprotective effects of dexmedetomidine, including the regulation of programmed cell death, autophagy and fibrosis, alleviation of inflammatory response, endothelial dysfunction and microcirculatory derangements, improvement of mitochondrial dysregulation, hemodynamics, and arrhythmias. Dexmedetomidine may play a promising and beneficial role in the treatment of cardiovascular disease.

Role of dexmedetomidine in modifying immune paralysis in patients with septic shock: randomized controlled trial

BACKGROUND

Immune paralysis can be defined as a hypoinflammatory state associated with the incapacity of the immune system to release proinflammatory mediators despite the clearance of pathogens by antimicrobials. Persistent immune paralysis leads to failure to eradicate primary infections with a substantial increase in the risk of multiorgan dysfunction and mortality. The state of immune paralysis is caused mainly by the diminished ability of monocytes to release proinflammatory cytokines in response to endotoxin. This phenomenon is known as endotoxin tolerance. This study aimed to assess the role of dexmedetomidine in modifying immune paralysis in septic shock patients.

METHODS

Twenty-four patients with septic shock were randomized into two groups of 12 patients. A continuous intravenous infusion of dexmedetomidine started at 0.15 µg kg-1 hr-1 and adjusted by 0.15 µg kg-1 h-1 to a maximum of 0.75 µg kg-1 h-1 (10 ml h-1), while midazolam was started at 1 mg h-1 (2 mL hr-1) and adjusted by 1 mg h-1 to a maximum of 5 mg h-1 (10 mL h-1). All infusions were adjusted by increments of 2 mL/hr-1 to maintain blinding. Serum levels of CD42a+/CD14+, HLADR+/CD14+, CRP, IL-6, IL-10 and TNF-α were measured at baseline (T1), 12 h (T2), and 24 h (T3).

RESULTS

Treatment with dexmedetomidine yielded no significant difference in CD42a+/CD14+, HLADR+/CD14, CD24b-MFI, HLADR-MFI, IL6 and TREM1 at all time points when compared with midazolam treatment. There was no significant difference in TLR levels between the two groups. Cardiac output in the dexmedetomidine group showed a significant decrease at 6, 12 and 24 h (P = 0.033, 0.021, and 0.005, respectively) compared with that in the midazolam group.

CONCLUSION

Our results indicated that dexmedetomidine did not affect CD42a+/CD14+ and HLA-DR+/CD14+ expression in septic patients. Furthermore, cytokine production and inflammatory biomarkers did not change with dexmedetomidine infusion. Trial registration Clinical trial.gov registry (NCT03989609) on June 14, 2019, https://register.

CLINICALTRIALS

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Dose-related effects of dexmedetomidine on sepsis-initiated lung injury in rats

Background

Sepsis is one of the leading causes of death in intensive care units. Dexmedetomidine is a sedative agent with anti-inflammatory properties. This study is designed to differentiate the impact of two different doses of dexmedetomidine on lung injury induced by sepsis.

Methods

Adult male Wistar rats were randomly divided into four groups: sham (n = 6), control (n = 12), 5DEX (n = 12), and 10DEX (n = 12). Cecal ligation puncture (CLP) was applied for sepsis initiation. The 5DEX group received 5 μg.kg^-1.h^-1 and the 10DEX group received 10 μg.kg^-1.h^-1 dexmedetomidine intravenous infusions for a 1-hour period. Six hours after CLP, tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and intercellular adhesion molecule-1 (ICAM-1) levels were analyzed in blood samples. Twenty-four hours after CLP, lung samples from the remaining rats were collected for the measurement of myeloperoxidase (MPO) activity, histological examination, and TdT- (terminal deoxynucleotidyl transferase) mediated fluorescent-dUTP labeling staining for apoptosis detection.

Results

Serum cytokine release, MPO activity, and apoptosis in the lung were significantly increased in the CLP group compared with the sham and dexmedetomidine groups (p < 0.05). TNF-α, ICAM-1, and MPO were significantly lower in the 10DEX group compared with both 5DEX and control groups, while IL-1β, total injury score, and apoptotic cell count had significantly lower values in both 10DEX and 5DEX groups compared with the control group (p < 0.05).

Conclusion

Dexmedetomidine administration played a protective role against CLP-induced lung injury. High-dose dexmedetomidine was needed for suppressing the leukocyte-mediated lung injury and apoptosis of lung tissue.

Dexmedetomidine Alleviates LPS-Induced Neuronal Dysfunction by Modulating the AKT/GSK-3β/CRMP-2 Pathway in Hippocampal Neurons

OBJECTIVE

Dexmedetomidine, an α2-adrenergic receptor agonist, mitigates cognitive dysfunction in elderly patients after surgery with general anesthesia. However, the underlying mechanism by which dexmedetomidine reduces cognitive dysfunction remains to be fully elucidated. The aim of this study was to investigate the effects of dexmedetomidine on lipopolysaccharide (LPS)-induced neuronal dysfunction in cultured hippocampal neurons.

METHODS

LPS, in the presence and absence of dexmedetomidine, was applied to cultured hippocampal neurons to mimic post-surgical inflammation. Neuronal morphology, including neurite outgrowth and synaptic transmission, was observed, and miniature excitatory postsynaptic currents were recorded by electrophysiological patch-clamp.

RESULTS

LPS significantly impaired neurite outgrowth in hippocampal neurons in a concentration- and time-dependent manner, which was reversed by dexmedetomidine treatment. Electrophysiological patch-clamp results showed that LPS induced synaptic transmission dysfunction, which was restored after dexmedetomidine addition. Furthermore, Western blotting assays showed that LPS suppressed the AKT/GSK-3β/CRMP-2 signaling pathway and dexmedetomidine countered the inhibitory effect of LPS by re-activating this pathway.

CONCLUSION

In general, dexmedetomidine protected against the effects of LPS-induced hippocampal neuron damage, including neurite outgrowth and synaptic transmission. Overall, dexmedetomidine modulated the AKT/GSK-3β/CRMP-2 signaling pathway to alleviate LPS-induced neurological dysfunction.

Dexmedetomidine protects against endothelial injury in septic rats induced by cecal ligation and puncture by decreasing angiopoietin 2 and increasing vascular endothelial cadherin levels

The aim of the present study was to investigate the protective effect of dexmedetomidine (Dex) on endothelial injury in a cecal ligation and puncture (CLP)-induced rat model of sepsis. A total of 36 male Sprague-Dawley rats were divided into three groups: Sham, CLP and CLP + Dex. The wet/dry (W/D) ratio of lung weight, hematoxylin and eosin (H&E) staining of lung tissue, plasma levels of angiopoietin (Ang)1 and 2, ratio of Ang2/1 and vascular endothelial (VE)-cadherin protein expression levels in lung tissue were determined. The W/D ratio of lung tissue in the CLP + Dex group was significantly lower than that in the CLP group (P<0.01). The H&E staining results indicated that Dex treatment reduced the levels of CLP-induced alveolar septum widening, infiltrating white blood cells and congestion, when compared with CLP alone. In addition, the expression levels of plasma Ang2 and the Ang2/1 ratio in the CLP + Dex group were significantly lower than those of the CLP rats (P<0.01). Furthermore, the level of VE-cadherin protein in lung tissue of the CLP + Dex group was higher than that of the CLP group (P<0.05). The results indicated that Dex had a protective effect against CLP-induced endothelial injury, through the ability to reduce expression of the endothelial injury factor Ang2 and increase the expression of the endothelial adhesion junction factor VE-cadherin in a septic rat model. These data suggest a potential application of Dex in the clinical treatment of sepsis.

The role of the cholinergic anti-inflammatory pathway in septic cardiomyopathy

Septic cardiomyopathy (SCM)is common in septic patients and results in cardiovascular failure. The pathogenesis of SCM is complicated, and patients with SCM have high mortality because current treatment methods are limited. The cholinergic anti-inflammatory pathway (CAP) modulates inflammatory responses through vagus nerve stimulation that leads to the release of acetylcholine (ACh), which binds to the alpha7 nicotinic acetylcholine receptor (α7nAChR). Moreover, α7nAChR activation by its agonists at the tissue level inhibits inflammatory mediators and regulates the function of immune cells in sepsis. Therefore, the α7nAChR can maintain balance of the inflammatory-immune response in sepsis. CAP has been elucidated as a critical regulator of anti-inflammation in many diseases, including rheumatoid arthritis, inflammatory boweldisease and SCM. Additionally, some clinical and preclinical trials show therapeutic potential via regulating CAP. There are excellent studies regarding the beneficial role of CAP activation, especially α7nAChR, in experimental SCM. This review aims to discuss the CAP in attenuating inflammation and the potential role of α7nAChR activation in regulating immune and reducing inflammation in SCM.

Effect of neutrophil CD64 for diagnosing sepsis in emergency department

BACKGROUND

The aim of this study is to investigate the diagnostic and prognostic value of neutrophil CD64 (nCD64) as a novel biomarker in sepsis patients.

METHODS

One hundred fifty-one adult patients diagnosed with sepsis and 20 age-matched healthy controls were enrolled in the study. Patients with sepsis were further subdivided into a sepsis group and a septic shock group. nCD64 expression, serum procalcitonin (PCT) level, C-reactive protein (CRP) level, and white blood cell (WBC) count were obtained for each patient, and Sequential Organ Failure Assessment (SOFA) scores were calculated.

RESULTS

nCD64 expression was higher in the sepsis group with confirmed infection than in the control group. The receiver operating characteristic (ROC) curve of nCD64 was higher than those of SOFA score, PCT, CRP and WBC for diagnosing infection. The area under the curve (AUC) of nCD64 combined with SOFA score was the highest for all parameters. The AUC of nCD64 for predicting 28-day mortality in sepsis was significantly higher than those of PCT, CRP, and WBC, but slightly lower than that of SOFA score. The AUC of nCD64 or PCT combined with SOFA score was significantly higher than that of any single parameter for predicting 28-day mortality.

CONCLUSION

nCD64 expression and SOFA score are valuable parameters for early diagnosis of infection and prognostic evaluation of sepsis patients.

Dexmedetomidine protects aged rats from postoperative cognitive dysfunction by alleviating hippocampal inflammation

The present study investigated the effect of dexmedetomidine on hippocampal inflammation and cognitive function in rats with postoperative cognitive dysfunction (POCD). A total of 80 healthy male Sprague Dawley rats were used, 72 of which developed POCD. The rats were randomly divided into four groups: The control, model, low-dose and high-dose dexmedetomidine anesthesia groups. A POCD model was established and dexmedetomidine was administered. Cognitive function tests were performed and expression levels of interleukin 1β (IL-1β), tumor necrosis factor-α (TNF-α) and NF-κB biomarkers were evaluated on the first, third and seventh day following modeling. The cognitive function of rats was measured using a Y-maze test. The expression levels of IL-1β and TNF-α in the hippocampus were determined by ELISA. The protein expression levels of NF-κB p65 in the hippocampus were determined by western blotting. It was revealed that at 1, 3 and 7 days after surgery, there were no alterations in the exercise ability of rats in the different groups, as reflected by the number of rats passing the alternative arms in the Y-maze. On the first and third day after surgery, the cognitive dysfunction reflected by the alteration scores of the low-dose and high-dose dexmedetomidine anesthesia groups were significantly higher than those of the model group, and the increase in the high-dose group was more pronounced. Additionally, on the first day after surgery, the expression levels of IL-1β, TNF-α and NF-κB in the hippocampi of rats in the low- and high-dose dexmedetomidine anesthesia groups were significantly lower than those in the model group, and the decrease was more pronounced in the high-dose group. At 7 days after surgery, the differences in expression levels of IL-1β, TNF-α and NF-κB in the hippocampus among groups were not identified to be statistically significantly different. Taken together, the results of the present study indicated that dexmedetomidine may inhibit hippocampal inflammation induced by surgical trauma, and that dexmedetomidine may effectively improve postoperative cognitive function in rats.

Hypothermic properties of dexmedetomidine provide neuroprotection in rats following cerebral ischemia-reperfusion injury

Dexmedetomidine (Dex) is a sedative and analgesic agent that is widely administered to patients admitted to the intensive care unit, and has been demonstrated to result in hypothermia. Many patients have been revealed to benefit from therapeutic hypothermia, which can mitigate cerebral ischemia/reperfusion (I/R) injury following successful cardiopulmonary resuscitation. However, studies investigating the efficacy of Dex in I/R treatment is lacking. The present study aimed to investigate the efficacy of Dex in mitigating neuronal damage, and to determine the possible mechanism of its effects in a rat model of cardiac arrest (CA). CA was induced in Sprague-Dawley rats by asphyxiation for 5 min. Following successful resuscitation, the surviving rats were randomly divided into two treatment groups; one group was intraperitoneally administered with Dex (D group), whereas the control group was treated with normal saline (N group). Critical parameters, including core temperature and blood pressure were monitored following return of spontaneous circulation (ROSC). Arterial blood samples were collected at 10 min after surgery (baseline) 30 and 120 min post-ROSC; and neurological deficit scores (NDS) of the rats were taken 12 or 24 h after ROSC prior to euthanasia. The hippocampal tissue was then removed for analysis by histology, electron microscopy and western blotting. Rats in the D group exhibited a lower core temperature and higher NDS scores compared with the N group (P<0.05). In addition, Dex injection resulted in reduced expression of apoptotic and autophagy-associated factors in the hippocampus (P<0.05). Dex treatment induced hypothermia and improved neurological function in rats after ROSC following resuscitation from CA by inhibiting neuronal apoptosis and reducing autophagy, which suggested that Dex may be a potential therapy option for patients with CA.

Dexmedetomidine effects in different experimental sepsis in vivo models

Sepsis is a major cause of death and the most common cause of death among critically ill, non-ICU patients. Dexmedetomidine (DEX), an <alpha>₂ adrenergic receptor agonist, presents sympatholytic action in certain parts of the brain with anxiolytic, sedative, and pain killing effects. Additionally, through the activation of <alpha>₇ nicotinic acetylcholine receptor receptors, DEX reduces cytokine transcription and inhibits inflammation, rendering it beneficial during septic conditions. Moreover, there is a lot of interest in designing experimental sepsis models, where the administration of DEX is evaluated for its impact on multiple systems. This review focuses on experimental studies published between 1999 to March 2019 that were using DEX administration in sepsis in vivo models. From these, 36 articles were selected and summarized. Overall results show evidence that DEX may decrease mortality and inhibit inflammation, as it enhances the activity of the immune system while reducing its systemic reaction and lowering cytokine concentrations. Moreover DEX succeeds to alleviate heart injury during sepsis, acting beneficially for microcirculation and shows a neuroprotective role by inhibiting apoptotic pathways. In addition, DEX appears to have a protective role for liver and spleen as well as a beneficial role for the function of lungs and kidneys as it reduces sepsis-induced injuries and apoptosis in intra-abdominal experimental sepsis models.

Efficacy of dexmedetomidine for treatment of patients with sepsis: A meta-analysis of randomized controlled trials

BACKGROUND

This meta-analysis aimed to evaluate the effect of dexmedetomidine on prognosis in patients with sepsis.

METHODS

Computer-related electronic databases were searched, including PubMed, Embase, Web of Science, the Cochrane Library, and the China National Knowledge Infrastructure, from the date of database construction to January 2019. Stata 12.0 was used to perform a meta-analysis of short-term mortality [intensive care unit (ICU) mortality or 28-day mortality], ICU length of stay, and mechanical ventilation. Mortality was expressed using risk ratio (RR) and 95% confidence interval (CI). ICU length of stay and mechanical ventilation were expressed as weighted mean difference (WMD) and 95% CIs.

RESULTS

We finally included 8 randomized controlled trials in this meta-analysis. Compared with the control group, the dexmedetomidine group had a lower occurrence of 28-day mortality (RR, 0.49; 95% CI, 0.35 to 0.69; P = .000) and ICU mortality (RR, 0.44; 95% CI, 0.23 to 0.84; P = .013). However, there was no statistically significant difference for the length of hospital stay (WMD, -0.05; 95% CI, -0.59 to 0.48; P = .840) and mechanical ventilation time (WMD, 1.05; 95% CI, -0.27 to 2.37; P = .392) between dexmedetomidine group and control group.

CONCLUSIONS

In patients with sepsis, dexmedetomidine can reduce the short-term mortality of patients, but could not shorten the ICU length of stay and mechanical ventilation time. More clinical randomized controlled trials are needed to verify the efficacy and safety of dexmedetomidine on the length of hospital stay and mechanical ventilation time.

Dose-related effects of dexmedetomidine on immunomodulation and mortality to septic shock in rats

BACKGROUND

Dexmedetomidine has already been used in septic patients as a new sedative agent, few studies have examined its effects on immunomodulation. Therefore, the authors have designed a controlled experimental study to characterize the immunomodulation effects of dexmedetomidine in the cecal ligation and puncture (CLP) model in rats.

METHODS

After CLP, 48 Wistar rats were randomly allocated into four groups: (1) CLP group; (2) small-dose treatment group (2.5 μg·kg^-1·h^-1); (3) medium-dose treatment group (5.0 μg·kg^-1· h^-1); and (4) large-dose treatment group (10.0 μg·kg^-1·h^-1). HLA-DR and plasma cytokine (IL-4, IL-6, IL-10 and TNF-α) levels were measured, and the mean arterial blood pressure (MAP), heart rate (HR), arterial blood gases, lactate concentrations and mortality were also documented.

RESULTS

The HLA-DR level, inflammatory mediator levels, MAP and HR had no obvious changes among Dexmedetomidine treatment groups (DEX groups). Compared with the CLP group, the DEX groups exhibited decreased HLA-DR levels (P_group=0.0202) and increased IL-6 production, which was increased at 3 h (P= 0.0113) and was then attenuated at 5 h; additionally, the DEX groups exhibited decreased HR (P<0.001) while maintaining MAP (P_group=0.1238), and remarkably improving lactate (P<0.0001). All of these factors led to a significant decrease in the mortality, with observed rates of 91.7%, 66.7%, 25% and 18% for the CLP, DEX2.5, DEX5.0, DEX10.0 groups, respectively.

CONCLUSION

Dexmedetomidine treatment in the setting of a CLP sepsis rat model has partially induced immunomodulation that was initiated within 5 h, causing a decreased HR while maintaining MAP, remarkably improving metabolic acidosis and improving mortality dose-dependently.