Effects of alpha- and beta-adrenergic agonists on Toxoplasma gondii infection in murine macrophages

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

gov .

Dexmedetomidine improves the outcomes for pediatric severe sepsis with mechanical ventilation

BACKGROUND

The sedative dexmedetomidine has been shown to reduce mortality in adult patients with severe sepsis, but it is not known whether children benefit. This study explored the effects of dexmedetomidine on the outcomes of children with severe sepsis with mechanical ventilation.

METHODS

In this retrospective cohort study, children with severe sepsis requiring mechanical ventilation from 2016 to 2020 were categorized as dexmedetomidine and non-dexmedetomidine group. The propensity score matching was performed to match cases in both groups. The primary outcome was 28-day mortality, and the secondary outcomes were acute kidney injury, ventilator-free days, lengths of PICU and hospital stays. The Kaplan-Meier method and was the log-rank test used to estimate the 28-day mortality rate and assess between-group differences.

RESULTS

In total, 250 patients were eligible patients: 138 in the dexmedetomidine group and 112 in the non-dexmedetomidine group. After 1:1 propensity score matching, 61 children in each group. dexmedetomidine group showed more lower 28-day mortality (9.84% vs. 26.23%, P = 0.008). During the 7-day observation period after PICU admission, the dexmedetomidine group showed significantly lower neurological and renal sub-scores at day 7 and serum creatinine level at day 3 and day 7. There were no statistical differences in the incidence of acute kidney injury, ventilator-free days, lengths of PICU and hospital stays between the two groups.

CONCLUSIONS

dexmedetomidine treatment in children with severe sepsis is associated with better outcomes and should therefore be considered for the sedation strategy.

Dexmedetomidine and Mortality From Sepsis Requiring Mechanical Ventilation: A Japanese Nationwide Retrospective Cohort Study

BACKGROUND

Dexmedetomidine has a mild sedative effect and may reduce mortality in mechanically ventilated critically ill patients. However, few studies have examined the effects of dexmedetomidine in patients with sepsis who require mechanical ventilation. The aim of this study was to investigate the association between dexmedetomidine and mortality in patients with sepsis requiring mechanical ventilation, using a nationwide inpatient database in Japan.

METHODS

Using the Diagnosis Procedure Combination database from July 1, 2010, to March 31, 2016, we identified adult patients with sepsis who required mechanical ventilation for more than 2 days. Patients were divided into those who received dexmedetomidine and those who received midazolam or propofol within 1 day after admission. Logistic regression analysis, propensity score-matched analysis, and instrumental variable analysis were performed to compare all-cause 28-day mortality and duration of mechanical ventilation between the groups.

RESULTS

In total, 50 671 were eligible patients, including dexmedetomidine group (n = 13 759) and propofol or midazolam group (n = 36 912). The dexmedetomidine group had significantly lower all-cause 28-day mortality compared with the group receiving midazolam or propofol, as shown by the logistic regression analysis (odds ratio [OR]: 0.78; 95% confidence interval [CI]: 0.73-0.84), the propensity score-matched analysis (OR: 0.85; 95% CI: 0.80-0.91), and the instrumental variable analysis (OR: 0.64; 95% CI: 0.57-0.73). The duration of mechanical ventilation in the dexmedetomidine group was significantly shorter than that in the midazolam or propofol group.

CONCLUSIONS

Dexmedetomidine was associated with a reduction in all-cause 28-day mortality and duration of mechanical ventilation.

Effects of Dexmedetomidine on Intestinal Microcirculation and Intestinal Epithelial Barrier in Endotoxemic Rats

BACKGROUND

Dexmedetomidine reduces cytokine production in septic patients and reduces inflammation and mortality in experimental models of endotoxemia and sepsis. This study investigated whether dexmedetomidine attenuates endothelial dysfunction, intestinal microcirculatory dysfunction, and intestinal epithelial barrier disruption in endotoxemic rats.

METHODS

Ninety-two male Wistar rats were randomly assigned to the following four groups: (1) Sham; (2) lipopolysaccharide, received IV lipopolysaccharide 15 and 10 mg/kg at 0 and 120 min; (3) dexmedetomidine, received IV dexmedetomidine for 240 min; and (4) lipopolysaccharide + dexmedetomidine, received both lipopolysaccharide and dexmedetomidine. Sidestream dark-field videomicroscope, tissue oxygen monitor, and full-field laser perfusion image were used to investigate the microcirculation of the terminal ileum. Serum endocan level was measured. The Ussing chamber permeability assay, lumen-to-blood gadodiamide passage by magnetic resonance imaging, and bacterial translocation were conducted to determine epithelial barrier function. Mucosal apoptotic levels and tight junctional integrity were also examined.

RESULTS

The density of perfused small vessels in mucosa, serosal muscular layer, and Peyer patch in the lipopolysaccharide + dexmedetomidine group was higher than that of the lipopolysaccharide group. Serum endocan level was lower in the lipopolysaccharide + dexmedetomidine group than in the lipopolysaccharide group. Mucosal ratio of cleaved to full-length occludin and spleen bacterial counts were significantly lower in the lipopolysaccharide + dexmedetomidine group than in the lipopolysaccharide group.

CONCLUSION

The study finding suggests that dexmedetomidine protects against intestinal epithelial barrier disruption in endotoxemic rats by attenuating intestinal microcirculatory dysfunction and reducing mucosal cell death and tight junctional damage. (Anesthesiology 2016; 125:355-67).

The role of hormones on Toxoplasma gondii infection: a systematic review

Background:Toxoplasma gondii is the causal agent of toxoplasmosis in which one third of the world's population has been infected. In pregnant women, it may cause abortion and severe damage to the fetal central nervous system. During pregnancy, the prevalence of toxoplasmosis increases throughout the second and third quarter of gestation, simultaneously progesterone and 17β-estradiol also increase. Thus, it has been suggested that these hormones can aggravate or reduce parasite reproduction. The aim of this study was reviewing the relationship between hormones and infection caused by T. gondii in several experimental animal models and humans, focused mainly on: (a) congenital transmission, (b) parasite reproduction, (c) strain virulence, (d) levels of hormone in host induced by T. gondii infection, and (e) participation of hormone receptors in T. gondii infection. Are the hormones specific modulators of T. gondii infection? A systematic review methodology was used to consult several databases (Pub Med, Lilacs, Medline, Science direct, Scielo, Ebsco, Sprinker, Wiley, and Google Scholar) dated from September, 2013 to March, 2014.

Results: Thirty studies were included; eight studies in humans and 22 in animals and cell cultures. In the human studies, the most studied hormones were testosterone, progesterone, prolactin, and 17β-estradiol. Type I (RH and BK) and Type II (Prugniaud, SC, ME49, T45, P78, and T38) were the most frequent experimental strains.

Conclusions: Thirty-five years have passed since the first studies regarding T. gondii infection and its relationship with hormones. This systematic review suggests that hormones modulate T. gondii infection in different animal models. However, given that data were not comparable, further studies are required to determine the mechanism of hormone action in the T. gondii infectious process.

Locally injected dexmedetomidine inhibits carrageenin-induced inflammatory responses in the injected region

BACKGROUND

Dexmedetomidine, a highly selective agonist of α2-adrenoceptors, is a commonly used sedative; however, a potent anti-inflammatory effect has also been found. In the present study we evaluated the inhibitory effect of locally injected dexmedetomidine on inflammatory responses in the injected region.

METHODS

Local inflammation was induced in the hindpaws of male mice (aged 6-8 weeks) by intraplantar injection of lambda-carrageenin. To offset the central effect of tested agents, different agents were blindly injected into the left and right paws in the pairs of comparison. The effect of dexmedetomidine on edema (increase in paw volume), the accumulation of leukocytes, and production of tumor necrosis factor-α (TNF-α) and cyclooxygenase-2 (COX-2) were evaluated after carrageenin injection, using water displacement plethysmometry, histological imaging, immunohistochemistry, and Western blotting analysis. Furthermore, we also evaluated the effect of yohimbine, a full antagonist of α2-adrenoceptors, and phenylephrine, an agonist of the α1-adrenoceptor, on dexmedetomidine's action on inflammatory responses.

RESULTS

Paw volume and amount of leukocytes in the injected region significantly increased after the injection of carrageenin. Similarly, TNF-α and COX-2 production was found in the subcutaneous region injected with carrageenin, 4 hours after injection. Dexmedetomidine significantly inhibited all increases in paw volume, leukocytes, and production of TNF-α and COX-2. Furthermore, yohimbine significantly antagonized the anti-inflammatory effects of dexmedetomidine, whereas phenylephrine did not significantly alter them.

CONCLUSIONS

The findings suggest that locally injected dexmedetomidine exhibits an anti-inflammatory effect against local acute inflammatory responses, mediated by α2-adrenoceptors.

Effects of dexmedetomidine on inflammatory responses in patients undergoing laparoscopic cholecystectomy

BACKGROUND

Dexmedetomidine has been shown to reduce pro-inflammatory cytokine levels in rats with sepsis and in severely ill patients. The aim of this study was to document the effects of dexmedetomidine on inflammatory responses during and after surgery.

MATERIALS AND METHODS

Patients undergoing laparoscopic cholecystectomy were enrolled. After induction of anaesthesia, patients in the dexmedetomidine group (n = 24, group D) received a loading dose of dexmedetomidine (1.0 μg/kg), followed by infusion of dexmedetomidine at 0.5 μg/kg/h. A saline-treated group (n = 23, group S) served as a control. Intraoperative mean arterial pressure (MAP), heart rate (HR), and amount of rescue analgesic administered as post-anaesthetic care were compared between the groups. The pro-inflammatory cytokines tumour necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6, and anti-inflammatory cytokines IL-4 and IL-10 were quantified by sandwich enzyme-linked immunoassay at three times: after anaesthesia induction (T0), at the end of peritoneal closure (T1), and 60 min after surgery (T2). The C-reactive protein (CRP) level and leukocyte count were measured on post-operative day 1.

RESULTS

At time points T1 and T2, the IL-1β, TNF-α, and IL-10 levels were lower in group D than in group S (P < 0.05). The CRP level and leukocyte count on post-operative day 1 were also lower in group D (P < 0.05), as were intraoperative MAP, HR, and amount of rescue analgesic administered after surgery.

CONCLUSIONS

Dexmedetomidine administration during surgery reduced intraoperative and post-operative secretion of cytokines, as well as post-operative leukocyte count and CRP level.

Sedation & immunomodulation

As the armamentarium for sedation in the critically ill expands, opportunities will develop to modulate the immune responses of patients by way of the direct immune and neural-immune interactions of the sedatives. Control of autonomic activity through the use of appropriate sedation may be critical in this matter. Likewise analgesic-based sedation, with increased opioid dosage, may not prove beneficial in the setting of infection; whether avoidance of morphine in preference for a fentanyl derivative will help is unclear. However, as the immune effects seem dependent on the m receptor, it is improbable that a significant difference would be uncovered. Similarly, the present evidence suggests benzodiazepines are deleterious in infection; further studies are required urgently to evaluate this evidence. As an alternative to benzodiazepine-based sedation, dexmedetomidine has shown a remarkable 70% mortality benefit in a small secondary analysis of septic patients from the MENDS trial. Further powered clinical studies should now be undertaken to investigate the potential benefit of the α2-adrenoceptor agonist in this setting, with comparisons with propofol.

A screen against Leishmania intracellular amastigotes: comparison to a promastigote screen and identification of a host cell-specific hit

The ability to screen compounds in a high-throughput manner is essential in the process of small molecule drug discovery. Critical to the success of screening strategies is the proper design of the assay, often implying a compromise between ease/speed and a biologically relevant setting. Leishmaniasis is a major neglected disease with limited therapeutic options. In order to streamline efforts for the design of productive drug screens against Leishmania, we compared the efficiency of two screening methods, one targeting the free living and easily cultured promastigote (insect–infective) stage, the other targeting the clinically relevant but more difficult to culture intra-macrophage amastigote (mammal-infective) stage. Screening of a 909-member library of bioactive compounds against Leishmania donovani revealed 59 hits in the promastigote primary screen and 27 in the intracellular amastigote screen, with 26 hits shared by both screens. This suggested that screening against the promastigote stage, although more suitable for automation, fails to identify all active compounds and leads to numerous false positive hits. Of particular interest was the identification of one compound specific to the infective amastigote stage of the parasite. This compound affects intracellular but not axenic parasites, suggesting a host cell-dependent mechanism of action, opening new avenues for anti-leishmanial chemotherapy.

Leishmaniasis, a disease caused by protozoan parasites of the genus Leishmania, is a poverty-related disease threatening 350 million people throughout the world. Drugs currently available to treat this disease are toxic to the patient and drug-resistant parasites are emerging. New therapeutics are therefore needed. Fortunately, interest in confronting the treatment challenges has grown and new technology has led to an increase in high-throughput screens conducted against Leishmania. In order to gain insight into the most efficient screening strategy, we compared two methods, one targeting the easily cultured insect-infective promastigote stage of the parasite, and the other, targeting the clinically relevant but more difficult to culture intracellular amastigote stage. We show that while a screen against promastigotes is amenable to automation, it fails to recognize all active compounds. These compounds revealed only by an intracellular assay might act on host cell pathways important for parasite development. Targeting such pathways is an emerging strategy in drug discovery against infectious diseases.

Effect of dexmedetomidine versus lorazepam on outcome in patients with sepsis: an a priori-designed analysis of the MENDS randomized controlled trial

INTRODUCTION

Benzodiazepines and alpha2 adrenoceptor agonists exert opposing effects on innate immunity and mortality in animal models of infection. We hypothesized that sedation with dexmedetomidine (an alpha2 adrenoceptor agonist), as compared with lorazepam (a benzodiazepine), would provide greater improvements in clinical outcomes among septic patients than among non-septic patients.

METHODS

In this a priori-determined subgroup analysis of septic vs non-septic patients from the MENDS double-blind randomized controlled trial, adult medical/surgical mechanically ventilated patients were randomized to receive dexmedetomidine-based or lorazepam-based sedation for up to 5 days. Delirium and other clinical outcomes were analyzed comparing sedation groups, adjusting for clinically relevant covariates as well as assessing interactions between sedation group and sepsis.

RESULTS

Of the 103 patients randomized, 63 (31 dexmedetomidine; 32 lorazepam) were admitted with sepsis and 40 (21 dexmedetomidine; 19 lorazepam) without sepsis. Baseline characteristics were similar between treatment groups for both septic and non-septic patients. Compared with septic patients who received lorazepam, the dexmedetomidine septic patients had 3.2 more delirium/coma-free days (DCFD) on average (95% CI for difference, 1.1 to 4.9), 1.5 (-0.1, 2.8) more delirium-free days (DFD) and 6 (0.3, 11.1) more ventilator-free days (VFD). The beneficial effects of dexmedetomidine were more pronounced in septic patients than in non-septic patients for both DCFDs and VFDs (P-value for interaction = 0.09 and 0.02 respectively). Additionally, sedation with dexmedetomidine, compared with lorazepam, reduced the daily risk of delirium [OR, CI 0.3 (0.1, 0.7)] in both septic and non-septic patients (P-value for interaction = 0.94). Risk of dying at 28 days was reduced by 70% [hazard ratio 0.3 (0.1, 0.9)] in dexmedetomidine patients with sepsis as compared to the lorazepam patients; this reduction in death was not seen in non-septic patients (P-value for interaction = 0.11).

CONCLUSIONS

In this subgroup analysis, septic patients receiving dexmedetomidine had more days free of brain dysfunction and mechanical ventilation and were less likely to die than those that received a lorazepam-based sedation regimen. These results were more pronounced in septic patients than in non-septic patients. Prospective clinical studies and further preclinical mechanistic studies are needed to confirm these results.

TRIAL REGISTRATION

NCT00095251.

Mollaret meningitis may be caused by reactivation of latent cerebral toxoplasmosis

Mollaret meningitis (MM) occurs mainly in females and is characterized by recurrent episodes of headache, transient neurological abnormalities, and the cerebrospinal fluid containing mononuclear cells. HSV-2 was usually identified as the causative agent. Recently, we found that recurrent headaches in non-HIV-infected subjects were due to acquired cerebral toxoplasmosis (CT). The aim of the study was therefore to focus on molecular pathomechanisms that may lead to reactivation of latent CT and manifest as MM. Literature data cited in this work were selected to illustrate that various factors may affect latent CNS Toxoplasma gondii infection/inflammation intensity and/or host defense mechanisms, i.e., the production of NO, cytokines, tryptophan degradation by indoleamine 2,3-dioxygenase, mechanisms mediated by an IFN-gamma responsive gene family, limiting the availability of intracellular iron to T. gondii, and production of reactive oxygen/nitrogen species, finally inducing choroid plexitis and/or vasculitis. Examples of triggers revealing MM and accompanying disturbances of IFN-gamma-mediated immune responses that control HSV-2 and T. gondii include: female predominance (female mice are more susceptible to T. gondii infection than males); HSV-2 infection (increased IFN-gamma, IL-12); metaraminol (increased plasma catecholamine levels, changes in cytokine expression favoring T(H)2 cells responses); probably cholesterol contained in debris from ruptured epidermoid cysts (decreased NO; increased TNF-alpha, IL-6, IL-8). These irregularities induced by the triggers may be responsible for reactivation of latent CT and development of MM. Thus, subjects with MM should have test(s) for T. gondii infection performed obligatorily.

Sedation improves early outcome in severely septic Sprague Dawley rats

INTRODUCTION

Sepsis, a systemic inflammatory response to infective etiologies, has a high mortality rate that is linked both to excess cytokine activity and apoptosis of critical immune cells. Dexmedetomidine has recently been shown to improve outcome in a septic cohort of patients when compared to patients randomized to a benzodiazepine-based sedative regimen. We sought to compare the effects of dexmedetomidine and midazolam, at equi-sedative doses, on inflammation and apoptosis in an animal model of severe sepsis.

METHODS

After central venous access, Sprague Dawley rats underwent cecal ligation and intestinal puncture (CLIP) with an 18 G needle without antibiotic cover and received either saline, or an infusion of comparable volume of saline containing midazolam (0.6 mg.kg-1.h-1) or dexmedetomidine (5 ug.kg-1.h-1) for 8 hours. Following baseline measurements and CLIP, blood was sampled for cytokine measurement (tumour necrosis factor (TNF)-alpha and interleukin (IL)-6; n = 4-6 per group) at 2, 4 and 5 hours, and animal mortality rate (MR) was monitored (n = 10 per group) every 2 hours until 2 hours had elapsed. In addition, spleens were harvested and apoptosis was assessed by immunoblotting (n = 4 per group).

RESULTS

The 24 hour MR in CLIP animals (90%) was significantly reduced by sedative doses of either dexmedetomidine (MR = 20%) or midazolam (MR = 30%). While both sedatives reduced systemic levels of the inflammatory cytokine TNF-alpha (P < 0.05); only dexmedetomidine reduced the IL-6 response to CLIP, though this narrowly missed achieving significance (P = 0.05). Dexmedetomidine reduced splenic caspase-3 expression (P < 0.05), a marker of apoptosis, when compared to either midazolam or saline.

CONCLUSIONS

Sedation with midazolam and dexmedetomidine both improve outcome in polymicrobial severely septic rats. Possible benefits conveyed by one sedative regimen over another may become evident over a more prolonged time-course as both IL-6 and apoptosis were reduced by dexmedetomidine but not midazolam. Further studies are required to evaluate this hypothesis.

Sedation & immunomodulation

The management of critically ill patients necessitates the use of sedatives and analgesics to provide patient comfort and cooperation. These drugs exert profound effects on all organ systems, not only the central nervous system, and this article describes the immunologic effects of the commonly used critical care sedatives: propofol, the benzodiazepines, opioids, and alpha(2)-adrenoceptor agonists. Benzodiazepines, opioids, and possibly even propofol worsen outcome in animal models of infection, whereas preliminary evidence suggests that the alpha(2)-adrenoceptor agonist, dexmedetomidine, may improve outcomes in the setting of infection. Given the burden of sepsis and secondary infections in critical care, choice of sedation may need to be carefully considered to preserve immune responses in critically ill patients.