Perioperative acute kidney injury: The renoprotective effect and mechanism of dexmedetomidine

The Efficacy of Ferroptosis Inhibition on Ischemia-Reperfusion Injury of Abdominal Organs: A Systematic Review and Meta-analysis

Solid organ transplantation is hampered by complications that arise after ischemia-reperfusion injury (IRI), a detrimental type of injury for which no adequate treatment options are available. Ferroptosis, an iron-dependent form of regulated cell death, is a major driver of IRI. This systematic review and meta-analysis summarizes the effects of pharmacological ferroptosis inhibition in abdominal organs in the setting of IRI. PubMed, Embase, Web of Science and Cochrane were searched for concepts "ferroptosis" and "IRI" in August 2023. To allow for meta-analyses, inhibitors were divided into different intervention pathways: (I) lipophilic radical scavengers, (II) iron chelators, (III) antioxidants, (IV) lipid metabolism inhibitors, (V) combination treatments, and (VI) others. When available, organ function and injury effect sizes were extracted and used for random-effects meta-analyses. In total 79 articles were included, describing 59 unique inhibitors in kidney, liver, and intestinal IRI. No studies in pancreas were found. Overall bias and study quality was unclear and average to low, respectively. Apart from 1 clinical study, all inhibitors were tested in preclinical settings. The vast majority of the studies showed ferroptosis inhibition to be protective against IRI under various treatment conditions. In liver and kidney IRI, meta-analyses on standardized effect sizes from 43 articles showed a combined protective effect against IRI compared with a nontreated controls for all analyzed intervention pathways. In conclusion, ferroptosis inhibition protects against abdominal IRI in preclinical research. Important questions regarding optimal intervention pathway, bioavailability, optimal dosage, side effects etc. should be addressed before clinical introduction.

Intraoperative dexmedetomidine and acute kidney injury in paediatric noncardiac surgery: a retrospective propensity score-matched analysis

BACKGROUND

Paediatric acute kidney injury (AKI) is common and linked to longer hospitalisation and mortality. We investigated whether a continuous intraoperative infusion of dexmedetomidine, which increases renal blood flow, was associated with a lower risk of postoperative AKI in paediatric patients undergoing noncardiac surgery.

METHODS

This retrospective cohort study included paediatric patients undergoing noncardiac surgery between January 2019 and July 2021. Propensity score matching, based on the participants' baseline characteristics, was used to minimise the potential bias. The primary outcome was AKI within 7 days after surgery. The secondary outcomes included ICU admission, in-hospital mortality, length of hospitalisation, intraoperative bradycardia, and hypotension. The exposure of interest was continuous intraoperative infusion of dexmedetomidine at any dosage or duration. Multivariable logistic regression and linear regression analyses were further used to adjust for residual imbalanced intraoperative factors in the matched cohort.

RESULTS

After propensity score matching, we identified 1858/4091 paediatric patients who had received intraoperative dexmedetomidine infusion. Intraoperative dexmedetomidine infusion was associated with a lower risk of AKI (1.4% vs 3.2%; odds ratio 0.43, 95% confidence interval 0.27-0.66; P<0.001), postoperative ICU admission (odds ratio 0.35, 95% confidence interval 0.30-0.42; P<0.001), and shorter hospitalisation (7 [5-10] vs 9 [6-13] days; P<0.001). Intraoperative bradycardia, hypotension, and in-hospital mortality were similar between the matched groups.

CONCLUSIONS

This retrospective analysis of a single-centre paediatric noncardiac surgery cohort suggests that intraoperative dexmedetomidine infusion was associated with a lower incidence of AKI within 7 days after surgery.

CLINICAL TRIAL REGISTRATION

ChiCTR2300069115.

Dexmedetomidine preconditioning attenuates ferroptosis in myocardial ischemia-reperfusion injury via α2 adrenergic receptor activation

Objective

Dexmedetomidine (Dex) is a potent agonist of the α2 adrenergic receptor that has been shown to possess sedative and hypnotic properties. Dex can protect against myocardial ischemia-reperfusion injury (MIRI) by inhibiting ferroptosis. However, these studies were based on Dex post-conditioning, and the role of α2 adrenergic receptors in this process is unclear. In this study, we investigated whether Dex preconditioning can prevent MIRI by attenuating ferroptosis and whether this effect depends on α2 adrenergic receptors in rats.

Methods

Male Sprague-Dawley rats were randomly assigned to five groups: sham (saline-treated), I/R (ischemia-exposed), Dex + I/R (Dex pre-treatment), Dex + Yoh + I/R (Dex and yohimbine pre-treatment), and Yoh + I/R (yohimbine pre-treatment). Cardiac function, myocardial infarction, and morphological changes were assessed. Transmission electron microscopy was used to analyze mitochondrial morphology. Ferroptosis-related indicators and lipid peroxidation were measured using western blotting and qRT-PCR.

Results

Our findings indicated that Dex preconditioning improved cardiac function, reduced infarct size and apoptosis, and inhibited ferroptosis in the rat myocardium after MIRI. These effects were associated with the upregulation of Nrf2, SLC7A11, and GPX4 expression, as well as the downregulation of Ferritin, TFR1, ACSL4, COX2, IL-1β, IL-6, and TNF-α expression. Importantly, yohimbine, an α2 adrenergic receptor antagonist, abolished these protective effects.

Conclusion

These results suggest that Dex preconditioning can prevent MIRI by attenuating ferroptosis via α2 adrenergic receptor activation and by modulating the Nrf2/SLC7A11/GPX4 pathway.

Preclinical mitigation of 5-HT2B agonism-related cardiac valvulopathy revisited

Cardiac valvulopathy (Cardiac Valve Disease; CVD) associated with off-target activation of the 5-hydroxytryptamine (5-HT) 2B receptor has been well recognized, but is still poorly predicted during drug development. The regulatory guidance proposes the use of 5-HT2B binding data (i.e., Ki values) and free maximum therapeutic exposure (Cmax) to calculate safety margins as a threshold of detection (>10) for eliminating the risk of drug-induced cardiac valvulopathy. In this paper, we provide additional recommendations for preclinical prediction of CVD risk based on clinical pharmacodynamic and pharmacokinetic data obtained from drugs with or without 5-HT2B receptor activation. Our investigations showed that 5-HT2B agonist affinity of molecules tested in an in vitro 5-HT2B cell-based functional assay, placed in perspective to their sustained plasma exposure (AUCs) and not to their peak plasma exposure, Cmax (i.e., maximum therapeutic exposure) provide a solid basis for interpreting 5-HT2B data, for calculating safety margins and then, accurately differentiate drugs associated with a clinical risk of CVD from those which are not (despite having some agonist 5-HT2B activity). In addition, we discuss the risk of multi-organ fibrosis linked to 5-HT2B receptor activation, often underestimated, however well reported in FAERS for 5-HT2B agonists. We believe that our recommendations have the potential to mitigate the risk for the clinical development of CVD and fibrosis.