Dexmedetomidine relieved neuropathic pain and inflammation response induced by CCI through HMGB1/TLR4/NF-κB signal pathway

SGK1-HDAC4-HMGB1 signaling pathway in the spinal cord dorsal horn participates in diabetic neuropathic pain

PURPOSE

This study aimed to determine whether serum-and glucocorticoid-inducible kinase1 (SGK1) activation-dependent histone deacetylase 4 (HDAC4) phosphorylation, nucleocytoplasmic trafficking, and subsequent regulation of high-mobility group protein box 1 (HMGB1) expression are involved in type 2 diabetic neuropathic pain (DNP).

METHODS

The type 2 diabetic neuropathic pain model was established in rats by feeding them with a high-fat and high-sugar diet for 8 weeks and then fasting them for 12 h, followed by a single intraperitoneal injection of streptozotocin (STZ, 35 mg/kg). SGK1 was inhibited in the spinal cord by intrathecal administration of the SGK1 inhibitor GSK-650394.

RESULTS

The present study revealed that pSGK1/tSGK1 was persistently upregulated in the spinal cord of rats with type-2 DNP. The downregulation of pSGK1/tSGK1 through the intrathecal injection of the SGK1 inhibitor GSK-650394 significantly ameliorated the pain hypersensitivity, relieved the abnormal expression of pHDAC4/tHDAC4 and HMGB1, and affected HDAC4 nucleocytoplasmic trafficking in DNP rats.

CONCLUSION

Our data suggest that SGK1 in the spinal cord modulates type-2 DNP by regulating the HDAC4/HMGB1 pathway.

Comparison of the effects of remimazolam and dexmedetomidine on the quality of recovery in functional endoscopic sinus surgery: a randomized clinical trial

BACKGROUND

Postoperative pain usually occur in patients who have undergone functional endoscopic sinus surgery (FESS). Remimazolam and dexmedetomidine could enhance the quality of recovery (QoR) after surgery. The aim of this study was to compare the effects of remimazolam and dexmedetomidine with respect to the QoR-40 score of patients who have undergone FESS.

METHODS

A total of 120 patients (18-65 years) scheduled for FESS were randomly allocated to Group R, Group D or Group C. Group R received 0.075 mg/kg remimazolam loading and 0.1 mg/kg/h infusion. Group D received dexmedetomidine (1.0 µg/kg loading, 0.5 µg/kg/h infusion). Group C received a placebo equal to dexmedetomidine. Anaesthesia was induced with propofol, sufentanil and cisatracurium. Anaesthesia maintenance was performed via target-controlled infusions (TCIs) of propofol and remifentanil. The primary outcome was the QoR-40 score on the day before surgery and postoperative Day 1 (POD1). The secondary outcomes were the time to return to consciousness, length of stay in the PACU, sedation score upon PACU arrival, pain, postoperative nausea and vomiting (PONV) and cumulative consumption of propofol and remifentanil. Adverse effects were recorded.

RESULTS

The total QoR-40 scores (median, IQR) on POD1 decreased less (154.5, 152.0 -159.0) in Groups R and D (155.0, 154.8 -159.3) than in Group C (139.0, 136.8 -142.0) (P < 0.001). The time to return of consciousness and the length of stay in the PACU were significantly shorter in Groups R and C than in Group D (P < 0.001). The level of sedation upon PACU arrival (median, IQR) in Groups R (-2.0, -2.0--1.0) and D (-2.0, -3.0--2.0) was greater than that in Group C (1.0, 0.0 -1.0) (P < 0.001). The cumulative consumption rates of propofol and remifentanil in Groups R and D were lower than that in Group C (P < 0.001). Compared with that in Group C, the pain intensity was lower in Groups R and D (P < 0.001).The number of patients occurring PONV was less in Groups R (3/40) and D (4/40) than in Group C (11/40) (P = 0.024). Fifteen patients had bradycardia in Group D, whereas no bradycardia was noted in Groups R or C (P < 0.001).

CONCLUSION

Administration of remimazolam could provide a similar QoR to that of dexmedetomidine. In addition, remimazolam may be a promising option for improving the QoR of patients who have undergone FESS.

TRIAL REGISTRATION

ChiCTR2300076209. (Prospectively registered). The initial registration date was 27/9/2023.

Lentivirus-mediated RNA interference targeting HMGB1 modulates AQP1 to reduce pain induced by chronic compression of the dorsal root ganglia

Backgrounds

Neuropathic pain (NP) is a kind of chronic pain that has attracted much attention in clinical practice, characterized by high morbidity, complex mechanisms, and difficulties in clinical treatment, with which the activation of High mobility group box 1 (HMGB1) is closely related. The aim of this study was to investigate the effects of lentivirus-mediated RNA interference gene therapy targeting HMGB1 on neuropathic pain in rats with chronic dorsal root ganglion compression (CCD) and its specific mechanisms, so as to explore new pharmacological targets.

Methods

Adult male Wistar rats were surgically subjected to chronic compression of the dorsal root ganglia (CCD). Behavioral tests were performed by calculating the paw withdrawal mechanical threshold (PWMT) and the thermal paw withdrawal latency (TPWL). Co-immunoprecipitation (CO-IP) was used to clarify protein interactions. Gene silencing was induced by injecting lentivirus expressing HMGB1 short hairpin RNA (shRNA) into rats. An LPS-inflammation-stimulated rat astrocyte model was established to validate the animal experiment results further. Western blot analysis and real-time quantitative PCR were used to detect pathway protein expression.

Results

After first establishing the rat CCD model, both PWMT and PTWL were significantly reduced in rats, indicating that the model construction was successful. After lentiviral silencing of HMGB1 expression, NP was significantly alleviated in CCD rats. CO-IP experiments showed a link between HMGB1 and AQP1; After silencing HMGB1 expression, the expression of AQP1 was significantly reduced, and HMGB1 was able to modulate the effect of AQP1 on NP. Further use of an inhibitor of the HMGB1 receptor showed that after inhibition of RAGE, AQP1 was significantly reduced; HMGB1 may regulate AQP1 through its receptor RAGE to affect NP. Silencing of HMGB1 resulted in a significant decrease in NF-κB, and HMGB1 affects the inflammatory pathways it mediates. After silencing AQP1, NF-κB also decreased significantly, indicating that AQP1 is an upstream regulator of NF-κB.

Conclusion

Lentivirus-mediated RNA interference (RNAi) silencing targeting HMGB1 may play a key role in the development of neuropathic pain in rats by regulating AQP1 expression via RAGE and ultimately activating NF-κB.

Differential effects of dexmedetomidine on Gram-positive and Gram-negative bacterial killing and phagocytosis

Dexmedetomidine is a commonly used sedative in perioperative and intensive care settings with purported immunomodulatory properties. Since its effects on immune functions against infections have not been extensively studied, we tested the effects of dexmedetomidine on Gram-positive [Staphylococcus aureus and Enterococcus faecalis] and Gram-negative bacteria [Escherichia coli], and on effector functions of human monocytes THP-1 cells against them. We evaluated phagocytosis, reactive oxygen species (ROS) formation, and CD11b activation, and performed RNA sequencing analyses. Our study revealed that dexmedetomidine improved Gram-positive but mitigated Gram-negative bacterial phagocytosis and killing in THP-1 cells. The attenuation of Toll-like receptor 4 (TLR4) signaling by dexmedetomidine was previously reported. Thus, we tested TLR4 inhibitor TAK242. Similar to dexmedetomidine, TAK242 reduced E. coli phagocytosis but enhanced CD11b activation. The reduced TLR4 response potentially increases CD11b activation and ROS generation and subsequently enhances Gram-positive bacterial killing. Conversely, dexmedetomidine may inhibit the TLR4-signaling pathway and mitigate the alternative phagocytosis pathway induced by TLR4 activation through LPS-mediated Gram-negative bacteria, resulting in worsened bacterial loads. We also examined another α2 adrenergic agonist, xylazine. Because xylazine did not affect bacterial clearance, we proposed that dexmedetomidine may have an off-target effect on bacterial killing process, potentially involving crosstalk between CD11b and TLR4. Despite its potential to attenuate inflammation, we provide a novel insight into potential risks of dexmedetomidine use during Gram-negative infections, highlighting the differential effect of dexmedetomidine on Gram-positive and Gram-negative bacteria.

Dexmedetomidine protects cells from Angiotensin II-induced smooth muscle cell phenotype switch and endothelial cell dysfunction

Abdominal aortic aneurysm (AAA) is a vascular disorder greatly threatening life of the elderly population. Dexmedetomidine (DEX), an α2-adrenergic receptor agonist, has been shown to suppress AAA development. Nevertheless, the signaling pathways that might be mediated by DEX in AAA has not been clarified. Vascular smooth muscle cells (VSMCs) and endothelial cells (ECs) were treated with Angiotensin II (Ang II) to mimic AAA in vitro. BrdU, wound healing, and Transwell assays were utilized for measuring VSMC proliferation and migration. Western blotting was used for evaluating protein levels of contractile VSMC markers, collagens and matrix metalloproteinases (MMPs) in VSMCs as well as apoptosis- and HMGB1/TLR4/NF-κB signaling-related markers in ECs. Cell adhesion molecule expression and monocyte-endothelial adhesion were assessed by immunofluorescence staining and adhesion assays. Flow cytometry was implemented for analyzing EC apoptosis. Hematoxylin-eosin staining and ELISA were used to detect the effect of DEX in vivo. In this study, DEX inhibited Ang II-evoked VSMC phenotype switch and extracellular matrix degradation. DEX suppressed the inflammatory response and apoptosis of ECs induced by Ang II. DEX inhibited HMGB1/TLR4/NF-κB signaling pathway in Ang II-treated ECs. DEX attenuated Ang II-induced AAA and inflammation in mice. Overall, DEX ameliorates Ang II-induced VSMC phenotype switch, and inactivates HMGB1/TLR4/NF-κB signaling pathway to alleviate Ang II-induced EC dysfunction.

Perioperative Dexmedetomidine or Lidocaine Infusion for the Prevention of Chronic Postoperative and Neuropathic Pain After Gynecological Surgery: A Randomized, Placebo-Controlled, Double-Blind Study

Introduction

The transition of acute to chronic postoperative pain (CPP) remains a significant burden to the rehabilitation of patients. The research for adjuvants to prevent CPP continues; among others, dexmedetomidine and lidocaine seem promising agents.

Methods

This is a long-term follow-up of a randomized, placebo-controlled, double-blind study on women who underwent open abdominal gynecological surgery and received dexmedetomidine or lidocaine or placebo infusion perioperatively (n = 81). The effect of these adjuvants on the development of CPP and neuropathic pain was assessed during a 12-month follow-up. Eighty-one (81) women ASA I–II, aged between 30 and 70 years, were randomly assigned to receive either dexmedetomidine (DEX group) or lidocaine (LIDO group) or placebo (CONTROL group) perioperatively. Before anesthesia induction, all patients received a loading intravenous dose of either 0.6 μg/kg dexmedetomidine or 1.5 mg/kg lidocaine or placebo, followed by 0.6 μg/kg/h dexmedetomidine or 1.5 mg/kg/h lidocaine or placebo until last suture. Patients were followed up to obtain the long-term outcomes at 3, 6, and 12 months. At these time-points, pain intensity was assessed with the Numerical Rating Scale, (NRS: 0–10) and the development of neuropathic elements with the Douleur Neuropathique 4 (DN4) score. Prognostic parameters that could affect chronic pain and its components were also identified.

Results

Data from 74 women were analyzed. Dexmedetomidine significantly reduced NRS scores comparing to placebo at 3 months (p = 0.018), while at 6 months, lidocaine was found superior to placebo (p = 0.02), but not to dexmedetomidine, in preventing neuropathic pain (DN4 < 4). Regarding secondary endpoints, higher NRS cough scores at 48 h were associated with statistically significant NRS and DN4 scores at 3, 6, and 12 months (p < 0.02). At 6 months, a statistically significant correlation was also found between higher NRS values and older age (p = 0.020).

Conclusions

Dexmedetomidine was superior to placebo regarding the duration and severity of CPP, while lidocaine exhibited a protective effect against neuropathic elements of CPP.

Trial registration

ClinicalTrials.gov identifier, NCT03363425.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40122-022-00361-5.