Dexmedetomidine Preconditioning Protects Rats from Renal Ischemia-Reperfusion Injury Accompanied with Biphasic Changes of Nuclear Factor-Kappa B Signaling

Intraoperative dexmedetomidine administration and acute kidney injury in patients undergoing unilateral partial nephrectomy: a retrospective study

Partial nephrectomies are associated with an increased risk of acute kidney injury (AKI), but dexmedetomidine administration may improve renal outcomes. We hypothesized that intraoperative dexmedetomidine administration would be associated with a decrease in AKI development in patients undergoing unilateral partial nephrectomy. In this retrospective study, adult patients who underwent unilateral partial nephrectomy from April 2016 to October 2023 were included. Exclusion criteria were a history of end-stage renal disease, ineligible procedures (i.e., aborted procedure, conversion to radical nephrectomy, surgery on a horseshoe kidney), and reoperation within three days of the initial nephrectomy. Patients were categorized according to whether they received intraoperative dexmedetomidine. The primary outcome was AKI incidence within three days of surgery; AKI was defined according to the Kidney Disease Improving Global Outcomes definition. Propensity score matching (PSM) was conducted to account for potential confounders (age, body mass index, sex, American Society of Anesthesiologists score, final surgical approach, clamping-related ischemia for >15 min). We included 1,632 patients; 214 received dexmedetomidine and 1,418 did not. Before PSM, the AKI rate was 31.2% in patients who received dexmedetomidine and 25.7% in patients who did not (p = 0.081). After PSM, the AKI rate was 31.3% in patients who received dexmedetomidine and 27.6% in those who did not (p = 0.396). The post-PSM odds ratio for AKI following dexmedetomidine administration during unilateral partial nephrectomy was 0.910 (95% CI: 0.585-1.142; p = 0.677). Intraoperative dexmedetomidine was not associated with a reduction in postoperative AKI incidence or severity after unilateral partial nephrectomy.

The Dual-specificity Phosphatase 3 (DUSP3): A Potential Target Against Renal Ischemia/Reperfusion Injury

Renal ischemia/reperfusion (I/R) injury is a common clinical challenge faced by clinicians in kidney transplantation. I/R is the leading cause of acute kidney injury, and it occurs when blood flow to the kidney is interrupted and subsequently restored. I/R impairs renal function in both short and long terms. Renal ischemic preconditioning refers to all maneuvers intended to prevent or attenuate ischemic damage. In this context, the present review focuses on the dual-specificity phosphatase 3 (DUSP3), also known as vaccinia H1-related phosphatase, an uncommon regulator of mitogen-activated protein kinase (MAPK) phosphorylation. DUSP3 has different biological functions: (1) it acts as a tumor modulator and (2) it is involved in the regulation of immune response, thrombosis, hemostasis, angiogenesis, and genomic stability. These functions occur either through MAPK-dependent or MAPK-independent mechanisms. DUSP3 genetic deletion dampens kidney damage and inflammation caused by I/R in mice, suggesting DUSP3 as a potential target for preventing renal I/R injury. Here, we discuss the putative role of DUSP3 in ischemic preconditioning and the potential mechanisms of such an attenuated inflammatory response via improved kidney perfusion and adequate innate immune response.

Dexmedetomidine Protects Cortical Neurons from Propofol-Induced Apoptosis via Activation of Akt-IKK-NF-κB Signaling Pathway by α2A-adrenoceptor

CONTEXT

Propofol can induce neuroapoptosis. It has been reported that dexmedetomidine (DEX) has a protective effect on propofol-induced neuroapoptosis, but the specific mechanism needs to be further explored to provide a theoretical basis for their combined use.

OBJECTIVE

We aimed to explore the neuroprotective effect of DEX on primary cortical neurons treated by propofol and to elucidate the underlying mechanistic pathways.

METHODS

Cortical neurons were isolated from fetal rats and treated with propofol. MTT assays were performed to detect cell viability, α-tubulin immunofluorescent assays were conducted to observe cell abnormalities, and c-caspase3 immunofluorescent assays and flow cytometry were performed to examine cell apoptosis. Further, neurons were cotreated with propofol and DEX to study DEX's neuroprotective effects on propofol-caused neuronal injuries. Finally, the α2A-adrenoceptor was knocked out and/or the Akt activator (SC-79) was added to cells co-treated with propofol and DEX. The expression levels of Akt-IKK-NF-κB pathway-related proteins were detected by western blot.

RESULTS

Propofol decreased cell viability in a dose-dependent manner, triggered apoptosis, caused morphological abnormalities and down-regulated the phosphorylation levels of Akt, IKK, NF-κB and IκB in cortical neurons. DEX ameliorated the decrease of cell viability, alleviated neuronal apoptosis and promoted the downregulated expression levels of p-Akt, IKK, NF-κB, and IκB proteins which had been induced by propofol treatment. Western blot findings following the transfection of α2A-siRNA and the addition of SC-79 suggested that DEX's neuroprotective functions arose from the stimulation of α2A-adrenoceptors to activate the Akt-IKK-NF-κB signal pathway.

CONCLUSION

DEX protected neurons against propofol-induced apoptosis via activation of the Akt-IKK-NF-κB signal pathway through α2A-adrenoceptors.

Intrarenal Arterial Transplantation of Dexmedetomidine Preconditioning Adipose Stem-Cell-Derived Microvesicles Confers Further Therapeutic Potential to Attenuate Renal Ischemia/Reperfusion Injury through miR-122-5p/Erythropoietin/Apoptosis Axis

Intravenous adipose mesenchymal stem cells (ADSCs) attenuate renal ischemia/reperfusion (IR) injury but with major drawbacks, including the lack of a specific homing effect after systemic infusion, cell trapping in the lung, and early cell death in the damaged microenvironment. We examined whether intrarenal arterial transplantation of dexmedetomidine (DEX) preconditioning ADSC-derived microvesicles (DEX-MVs) could promote further therapeutic potential to reduce renal IR injury. We evaluated the effect of DEX-MVs on NRK-52E cells migration, hypoxia/reoxygenation (H/R)-induced cell death, and reactive oxygen species (ROS) amount and renal IR model in rats. IR was established by bilateral 45 min ischemia followed by 4 h reperfusion. Intrarenal MVs or DEX-MVs were administered prior to ischemia. Renal oxidative stress, hemodynamics and function, western blot, immunohistochemistry, and tubular injury scores were determined. The miR-122-5p expression in kidneys was analyzed using microarrays and quantitative RT-PCR and its action target was predicted by TargetScan. DEX-MVs were more efficient than MVs to increase migration capability and to further decrease H/R-induced cell death and ROS level in NRK-52E cells. Consistently, DEX-MVs were better than MV in increasing CD44 expression, improving IR-depressed renal hemodynamics and renal erythropoietin expression, inhibiting IR-enhanced renal ROS level, tubular injury score, miR-122-5p expression, pNF-κB expression, Bax/caspase 3/poly(ADP-ribose) polymerase (PARP)-mediated apoptosis, blood urea nitrogen, and creatinine levels. The use of NRK-52E cells confirmed that miR-122-5p mimic via inhibiting erythropoietin expression exacerbated Bax-mediated apoptosis, whereas miR-122-5p inhibitor via upregulating erythropoietin and Bcl-2 expression reduced apoptosis. In summary, intrarenal arterial DEX-MV conferred further therapeutic potential to reduce renal IR injury through the miR-122-5p/erythropoietin/apoptosis axis.

Carnosine alleviates diabetic nephropathy by targeting GNMT, a key enzyme mediating renal inflammation and fibrosis

Diabetic nephropathy (DN) is a common microvascular complication of diabetes and the main cause of end-stage nephropathy (ESRD). Inflammation and fibrosis play key roles in the development and progression of diabetic nephropathy. By using in vivo and in vitro DN models, our laboratory has identified the protective role of carnosine (CAR) on renal tubules. Our results showed that carnosine restored the onset and clinical symptoms as well as renal tubular injury in DN. Furthermore, carnosine decreased kidney inflammation and fibrosis in DN mice. These results were consistent with high glucose (HG)-treated mice tubular epithelial cells (MTECs). Using web-prediction algorithms, cellular thermal shift assay (CETSA) and molecular docking, we identified glycine N-methyltransferase (GNMT) as a carnosine target. Importantly, we found that GNMT, a multiple functional protein that regulates the cellular pool of methyl groups by controlling the ratio of S-adenosylmethionine (SAM) to S-adenosylhomocysteine (SAH), was down-regulated significantly in the serum of Type 1 DM patients and renal tissues of DN mice. Moreover, using cultured TECs, we confirmed that the increased GNMT expression by transient transfection mimicked the protective role of carnosine in reducing inflammation and fibrosis. Conversely, the inhibition of GNMT expression abolished the protective effects of carnosine. In conclusion, carnosine might serve as a promising therapeutic agent for DN and GNMT might be a potential therapeutic target for DN.

Organ-Protective Effects and the Underlying Mechanism of Dexmedetomidine

Dexmedetomidine (DEX) is a highly selective α2 adrenergic receptor (α2AR) agonist currently used in clinical settings. Because DEX has dose-dependent advantages of sedation, analgesia, antianxiety, inhibition of sympathetic nervous system activity, cardiovascular stabilization, and significant reduction of postoperative delirium and agitation, but does not produce respiratory depression and agitation, it is widely used in clinical anesthesia and ICU departments. In recent years, much clinical study and basic research has confirmed that DEX has a protective effect on a variety of organs, including the nervous system, heart, lungs, kidneys, liver, and small intestine. It acts by reducing the inflammatory response in these organs, activating antiapoptotic signaling pathways which protect cells from damage. Therefore, based on wide clinical application and safety, DEX may become a promising clinical multiorgan protection drug in the future. In this article, we review the physiological effects related to organ protection in α2AR agonists along with the organ-protective effects and mechanisms of DEX to understand their combined application value.