Role of interleukin-1beta in postoperative cognitive dysfunction

ML365 ameliorates postoperative cognitive impairment in aged mice by inhibiting NLRP3 inflammasome activation in the hippocampus

The aim of this study was to examine the effects of ML365, a two-pore potassium channel (K2P) inhibitor, on postoperative cognitive impairment (POCD). A mouse model of POCD was constructed by subjecting aged C57BL/6 mice to exploratory laparotomy. Changes in cognitive function were assessed using the Morris water maze test. Western blotting and qPCR were used to detect hippocampal NLRP3, Caspase-1 and IL-1β expression levels on days 3 and 7 post-surgery. Apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC) expression level was also assessed by western blotting. Pathological changes and nerve damage in the hippocampal CA1 and CA3 regions were detected by H&E staining, while the concentration of malondialdehyde (MDA) in the plasma was measured. We found that pretreatment with ML365 (administered intraperitoneally at a dose of 10 mg/kg) 30 min prior to exploratory laparotomy effectively ameliorated POCD in mice. ML365 pretreatment also reduced NLRP3, Caspase-1, ASC and IL-1β expression levels in the hippocampus, improved POCD-induced pathological changes in the hippocampal CA1 and CA3 areas of aged mice, and decreased levels of plasma MDA and oxidative stress. Together, our findings indicate that ML365 can alleviate POCD in mice by inhibiting NLRP3 inflammasome activation in the hippocampus.

Isoflurane-induced neuroinflammation and NKCC1/KCC2 dysregulation result in long-term cognitive disorder in neonatal mice

BACKGROUND

The inhalational anesthetic isoflurane is commonly utilized in clinical practice, particularly in the field of pediatric anesthesia. Research has demonstrated its capacity to induce neuroinflammation and long-term behavioral disorders; however, the underlying mechanism remains unclear [1]. The cation-chloride cotransporters Na+-K+-2Cl--1 (NKCC1) and K+-2Cl--2 (KCC2) play a pivotal role in regulating neuronal responses to gamma-aminobutyric acid (GABA) [2]. Imbalances in NKCC1/KCC2 can disrupt GABA neurotransmission, potentially leading to neural circuit hyperexcitability and reduced inhibition following neonatal exposure to anesthesia [3]. Therefore, this study postulates that anesthetics have the potential to dysregulate NKCC1 and/or KCC2 during brain development.

METHODS

We administered 1.5% isoflurane anesthesia to neonatal rats for a duration of 4 h at postnatal day 7 (PND7). Anxiety levels were assessed using the open field test at PND28, while cognitive function was evaluated using the Morris water maze test between PND31 and PND34. Protein levels of NKCC1, KCC2, BDNF, and phosphorylated ERK (P-ERK) in the hippocampus were measured through Western blotting analysis. Pro-inflammatory cytokines IL-1β, IL-6, and TNF-α were quantified using ELISA.

RESULTS

We observed a decrease in locomotion trajectories within the central region and a significantly shorter total distance in the ISO group compared to CON pups, indicating that isoflurane induces anxiety-like behavior. In the Morris water maze (MWM) test, rats exposed to isoflurane exhibited prolonged escape latency onto the platform. Additionally, isoflurane administration resulted in reduced time spent crossing in the MWM experiment at PND34, suggesting long-term impairment of memory function. Furthermore, we found that isoflurane triggered activation of pro-inflammatory cytokines IL-1β, IL-6, and TNF-α; downregulated KCC2/BDNF/P-ERK expression; and increased the NKCC1/KCC2 ratio in the hippocampus of PND7 rats. Bumetadine (NKCC1 specific inhibitors) reversed cognitive damage and effective disorder induced by isoflurane in neonatal rats by inhibiting TNF-α activation, normalizing IL-6 and IL-1β levels, restoring KCC2 expression levels as well as BDNF and ERK signaling pathways. Based on these findings, it can be speculated that BDNF, P-ERK, IL-1β, IL-6 and TNF - α may act downstream of the NKCC1/KCC2 pathway.

CONCLUSIONS

Our findings provide evidence that isoflurane administration in neonatal rats leads to persistent cognitive deficits through dysregulation of the Cation-Chloride Cotransporters NKCC1 and KCC2, BDNF, p-ERK proteins, as well as neuroinflammatory processes.

[Current challenges for therapy of comorbid patients: a new look at celecoxib. A review]

The use of non-steroidal anti-inflammatory drugs (NSAIDs) for a wide range of diseases is increasing, in part due to an increasing elderly population. Elderly patients are more vulnerable to adverse drug reactions, including side effects and adverse effects of drug-drug interactions, often occurring in this category of patients due to multimorbidity and polypharmacy. One of the most popular NSAIDs in the world is celecoxib. It is a selective cyclooxygenase (COX)-2 inhibitor with 375 times more COX-2 inhibitory activity than COX-1. As a result, celecoxib has a better gastrointestinal tract safety profile than non-selective NSAIDs. Gastrointestinal tolerance is an essential factor that physicians should consider when selecting NSAIDs for elderly patients. Celecoxib can be used in a wide range of diseases of the musculoskeletal system and rheumatological diseases, for the treatment of acute pain in women with primary dysmenorrhea, etc. It is also increasingly used as part of a multimodal perioperative analgesia regimen. There is strong evidence that COX-2 is actively involved in the pathogenesis of ischemic brain damage, as well as in the development and progression of neurodegenerative diseases, such as Alzheimer's disease. NSAIDs are first-line therapy in the treatment of acute migraine attacks. Celecoxib is well tolerated in patients with risk factors for NSAID-associated nephropathy. It does not decrease the glomerular filtration rate in elderly patients and patients with chronic renal failure. Many meta-analyses and epidemiological studies have not confirmed the increased risk of cardiovascular events reported in previous clinical studies and have not shown an increased risk of cardiovascular events with celecoxib, irrespective of dose. COX-2 activation is one of the key factors contributing to obesity-related inflammation. Specific inhibition of COX-2 by celecoxib increases insulin sensitivity in overweight or obese patients. Combination therapies may be a promising new area of treatment for obesity and diabetes.

Hippocampal HDAC6 promotes POCD by regulating NLRP3-induced microglia pyroptosis via HSP90/HSP70 in aged mice

BACKGROUND

Postoperative Cognitive Dysfunction (POCD) has attracted increased attention, but its precise mechanism remains to be explored. This study aimed to figure out whether HDAC6 could regulate NLRP3-induced pyroptosis by modulating the functions of HSP70 and HSP90 in microglia to participate in postoperative cognitive dysfunction in aged mice.

METHODS

Animal models of postoperative cognitive dysfunction in aged mice were established by splenectomy under sevoflurane anesthesia. Morris water maze was used to examine the cognitive function and motor ability. Sixteen-months-old C57BL/6 male mice were randomly divided into six groups: control group (C group), sham surgery group (SA group), splenectomy group (S group), splenectomy + HDAC6 inhibitor ACY-1215 group (ACY group), splenectomy + HDAC6 inhibitor ACY-1215 + HSP70 inhibitor Apoptozole group (AP group), splenectomy + solvent control group (SC group). The serum and hippocampus of mice were taken after mice were executed. The protein levels of HDAC6, HSP90, HSP70, NLRP3, GSDMD-N, cleaved-Caspase-1 (P20), IL-1β were detected by western blotting. Serum IL-1β, IL-6 and S100β were measured using ELISA assay, and cell localization of HDAC6 was detected by immunofluorescence. In vitro experiments, BV2 cells were used to validate whether this mechanism worked in microglia. The protein levels of HDAC6, HSP90, HSP70, NLRP3, GSDMD-N, P20, IL-1β were detected by western blotting and the content of IL-1β in the supernatant was measured using ELISA assay. The degree of acetylation of HSP90, the interaction of HSP70, HSP90 and NLRP3 were analyzed by coimmunoprecipitation assay.

RESULTS

Splenectomy under sevoflurane anesthesia in aged mice could prolong the escape latency, reduce the number of crossing platforms, increase the expression of HDAC6 and activate the NLRP3 inflammasome to induce pyroptosis in hippocampus microglia. Using ACY-1215 could reduce the activation of NLRP3 inflammasome, the pyroptosis of microglia and the degree of spatial memory impairment. Apoptozole could inhibit the binding of HSP70 to NLRP3, reduce the degradation of NLRP3 and reverse the protective effect of HDAC6 inhibitors. The results acquired in vitro experiments closely resembled those in vivo, LPS stimulation led to the pyroptosis of BV2 microglia cells and the release of IL-1β due to the activation of the NLRP3 inflammasome, ACY-1215 showed the anti-inflammatory effect and Apoptozole exerted the opposite effect.

CONCLUSIONS

Our findings suggest that hippocampal HDAC6 promotes POCD by regulating NLRP3-induced microglia pyroptosis via HSP90/HSP70 in aged mice.

Anesthesia/surgery activate MMP9 leading to blood-brain barrier disruption, triggering neuroinflammation and POD-like behavior in aged mice

Anesthesia and surgery activate matrix metalloproteinase 9 (MMP9), leading to blood-brain barrier (BBB) disruption and postoperative delirium (POD)-like behavior, especially in the elderly. Aged mice received intraperitoneal injections of either the MMP9 inhibitor SB-3CT, melatonin, or solvent, and underwent laparotomy under 3 % sevoflurane anesthesia(anesthesia/surgery). Behavioral tests were performed 24 h pre- and post-operatively. Serum and cortical tissue levels of interleukin (IL)-1β, IL-6, and tumor necrosis factor-α (TNF-α) were measured using ELISA. Levels of PDGFRβ, MMP9, tight junction, Mfsd2a, caveolin-1, synaptophysin, and postsynaptic densin (PSD)-95 proteins in the prefrontal cortex were assayed using Western blotting. BBB permeability was assessed by detecting IgG in the prefrontal cortex and serum S100β levels. Anesthesia/surgery-induced peripheral inflammation activated MMP9, which in turn injured pericytes and tight junctions and increased transcytosis, thereby disrupting the BBB. Impaired BBB allowed the migration of peripheral inflammation into the central nervous system (CNS), thereby inducing neuroinflammation, synaptic dysfunction, and POD-like behaviors. However, MMP9 inhibition reduced pericyte and tight junction injury and transcytosis, thereby preserving BBB function and preventing the migration of peripheral inflammation into the CNS, thus attenuating synaptic dysfunction and POD-like behavior. In addition, to further validate the above findings, we showed that melatonin exerted similar effects through inhibition of MMP9. The present study shows that after anesthesia/surgery, inflammatory cytokines upregulation is involved in regulating BBB permeability in aged mice through activation of MMP9, suggesting that MMP9 may be a potential target for the prevention of POD.

Propionic acid ameliorates cognitive function through immunomodulatory effects on Th17 cells in perioperative neurocognitive disorders

Background

Elderly patients undergoing surgery are prone to cognitive decline known as perioperative neurocognitive disorders (PND). Several studies have shown that the microglial activation and the decrease of short-chain fatty acids (SCFAs) in gut induced by surgery may be related to the pathogenesis of PND. The purpose of this study was to determine whether microglia and short-chain fatty acids were involved in cognitive dysfunction in aged rats.

Methods

Male wild-type Wistar rats aged 11-12 months were randomly divided into control group (Ctrl: Veh group), propionic acid group (Ctrl: PA group), exploratory laparotomy group (LP: Veh group) and propionic acid + exploratory laparotomy group (LP: PA group) according to whether exploratory laparotomy (LP) or PA pretreatment for 21 days was performed. The motor ability of the rats was evaluated by open field test on postoperative day 3 (POD3), and then the cognitive function was evaluated by Y-maze test and fear conditioning test. The expression of IL-1β, IL-6, RORγt and IL-17A mRNA in hippocampus was detected by RT-qPCR, the expression of IL-17A and IL-17RA in hippocampus was detected by Western blot, and the activation of microglia was detected by immunofluorescence.

Results

The PND rat model was successfully established by laparotomy. Compared with Ctrl: Veh group, the body weight of LP: Veh group decreased, the percentage of spontaneous alternations in Y maze decreased (P < 0.001), and the percentage of freezing time in contextual fear test decreased (P < 0.001). Surgery triggers neuroinflammation, manifested as the elevated levels of the inflammatory cytokines IL-1β (P < 0.001) and IL-6 (P < 0.001), the increased expression of the transcription factor RORγt (P = 0.0181, POD1; P = 0.0073, POD5)and major inflammatory cytokines IL-17A (P = 0.0215, POD1; P = 0.0071, POD5), and the increased average fluorescence intensity of Iba1 (P < 0.001, POD1; P < 0.001, POD5). After PA preconditioning, the recovery of rats in LP: PA group was faster than that in LP: Veh group as the body weight lost on POD1 (P = 0.0148) was close to the baseline level on POD5 (P = 0.1846), and they performed better in behavioral tests. The levels of IL-1β (P < 0.001) and IL-6 (P = 0.0035) inflammatory factors in hippocampus decreased on POD1 and the average fluorescence intensity of Iba1 decreased (P = 0.0024, POD1; P < 0.001, POD5), representing the neuroinflammation was significantly improved. Besides, the levels of RORγt mRNA (P = 0.0231, POD1; P = 0.0251, POD5) and IL-17A mRNA (P = 0.0208, POD1; P = 0.0071, POD5) in hippocampus as well as the expression of IL-17A (P = 0.0057, POD1; P < 0.001, POD5) and IL-17RA (P = 0.0388) decreased.

Conclusion

PA pretreatment results in reduced postoperative neuroinflammation and improved cognitive function, potentially attributed to the regulatory effects of PA on Th17-mediated immune responses.

Itaconate alleviates anesthesia/surgery-induced cognitive impairment by activating a Nrf2-dependent anti-neuroinflammation and neurogenesis via gut-brain axis

BACKGROUND

Postoperative cognitive dysfunction (POCD) is a common neurological complication of anesthesia and surgery in aging individuals. Neuroinflammation has been identified as a hallmark of POCD. However, safe and effective treatments of POCD are still lacking. Itaconate is an immunoregulatory metabolite derived from the tricarboxylic acid cycle that exerts anti-inflammatory effects by activating the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway. In this study, we investigated the effects and underlying mechanism of 4-octyl itaconate (OI), a cell-permeable itaconate derivative, on POCD in aged mice.

METHODS

A POCD animal model was established by performing aseptic laparotomy in 18-month-old male C57BL/6 mice under isoflurane anesthesia while maintaining spontaneous ventilation. OI was intraperitoneally injected into the mice after surgery. Primary microglia and neurons were isolated and treated to lipopolysaccharide (LPS), isoflurane, and OI. Cognitive function, neuroinflammatory responses, as well as levels of gut microbiota and their metabolites were evaluated. To determine the mechanisms underlying the therapeutic effects of OI in POCD, ML385, an antagonist of Nrf2, was administered intraperitoneally. Cognitive function, neuroinflammatory responses, endogenous neurogenesis, neuronal apoptosis, and Nrf2/extracellular signal-related kinases (ERK) signaling pathway were evaluated.

RESULTS

Our findings revealed that OI treatment significantly alleviated anesthesia/surgery-induced cognitive impairment, concomitant with reduced levels of the neuroinflammatory cytokines IL-1β and IL-6, as well as suppressed activation of microglia and astrocytes in the hippocampus. Similarly, OI treatment inhibited the expression of IL-1β and IL-6 in LPS and isoflurane-induced primary microglia in vitro. Intraperitoneal administration of OI led to alterations in the gut microbiota and promoted the production of microbiota-derived metabolites associated with neurogenesis. We further confirmed that OI promoted endogenous neurogenesis and inhibited neuronal apoptosis in the hippocampal dentate gyrus of aged mice. Mechanistically, we observed a decrease in Nrf2 expression in hippocampal neurons both in vitro and in vivo, which was reversed by OI treatment. We found that Nrf2 was required for OI treatment to inhibit neuroinflammation in POCD. The enhanced POCD recovery and promotion of neurogenesis triggered by OI exposure were, at least partially, mediated by the activation of the Nrf2/ERK signaling pathway.

CONCLUSIONS

Our findings demonstrate that OI can attenuate anesthesia/surgery-induced cognitive impairment by stabilizing the gut microbiota and activating Nrf2 signaling to restrict neuroinflammation and promote neurogenesis. Boosting endogenous itaconate or supplementation with exogenous itaconate derivatives may represent novel strategies for the treatment of POCD.

Postoperative cognitive disorders and delirium in gynecologic surgery: Which surgery and anesthetic techniques to use to reduce the risk?

Despite their general good health, an increasing proportion of elderly individuals require surgery due to an increase in average lifespan. However, because of their increased vulnerability, these patients need to be handled carefully to make sure that surgery does not cause more harm than good. Age-related postoperative cognitive disorders (POCD) and postoperative delirium (POD), two serious consequences that are marked by adverse neuropsychologic alterations after surgery, are particularly dangerous for the elderly. In the context of gynecologic procedures, POCD and POD are examined in this narrative review. The main question is how to limit the rates of POCD and POD in older women undergoing gynecologic procedures by maximizing the risk-benefit balance. Three crucial endpoints are considered: (1) surgical procedures to lower the rates of POCD and POD, (2) anesthetic techniques to lessen the occurrence and (3) the identification of individuals at high risk for post-surgery cognitive impairments. Risks associated with laparoscopic gynecologic procedures include the Trendelenburg posture and CO2 exposure during pneumoperitoneum, despite statistical similarities in POD and POCD frequency between laparoscopic and laparotomy techniques. Numerous risk factors are associated with surgical interventions, such as blood loss, length of operation, and position holding, all of which reduce the chance of complications when they are minimized. In order to emphasize the essential role that anesthesia and surgery play in patient care, anesthesiologists are vital in making sure that anesthesia is given as sparingly and quickly as feasible. In addition, people who are genetically predisposed to POCD may be more susceptible to the disorder. The significance of a thorough strategy combining surgical and anesthetic concerns is highlighted in this article, in order to maximize results for senior patients having gynecologic surgery.

Astrocytic phagocytosis in the medial prefrontal cortex jeopardises postoperative memory consolidation in mice

Memory impairment is one of the main characteristics of postoperative cognitive dysfunction. It remains elusive how postoperative pathological changes of the brain link to the memory impairment. The clinical setting of perioperation was mimicked via partial hepatectomy under sevoflurane anaesthesia together with preoperative restraint stress (Hep-Sev-stress) in mice. Memory changes were assessed with fear conditioning. The medial prefrontal cortex (mPFC)-dorsal hippocampus connectivity was evaluated with injecting neurotracer 28 days before surgery. Astrocytic activation was limited via injecting AAV-GFAP-hM4Di-eGFP into the mPFC. Astrocytic and microglial phagocytosis of synapses were visualised with co-labelling hippocampal neuronal axon terminals with PSD-95 and S100β or Iba1. Neuroinflammation and oxidative stress status were also detected. Hep-Sev-stress impaired the memory consolidation (mean [standard error], 49.91 [2.55]% vs. 35.40 [3.97]% in the contextual memory, p = 0.007; 40.72 [2.78]% vs. 27.77 [2.22]% in cued memory, p = 0.002) and the cued memory retrieval (39.00 [3.08]% vs. 24.11 [2.06]%, p = 0.001) in mice when compared with these in the naïve controls. Hep-Sev-stress damaged the connectivity from the dorsal hippocampus to mPFC but not from the mPFC to the dorsal hippocampus and increased the astrocytic but not microglial phagocytosis of hippocampal neuronal axon terminals in the mPFC. The intervention also induced neuroinflammation and oxidative stress in the dorsal hippocampus and the mPFC in a regional-dependent manner. Limiting astrocyte activation in the mPFC alleviated memory consolidation impairment induced by Hep-Sev-stress. Postoperative memory consolidation was impaired due to astrocytic phagocytosis-induced connectivity injury from the dorsal hippocampus to the medial prefrontal cortex.

Dietary Restriction Improves Perioperative Neurocognitive Disorders by Inhibiting Neuroinflammation and Gut Microbial Dysbiosis

Anesthesia/surgery have been identified as potential factors contributing to perioperative neurocognitive disorders, with a notably heightened risk observed in aging populations. One of the primary drivers of this impairment is believed to be neuroinflammation, specifically inflammation of hippocampal microglia. Dietary restriction has demonstrated a favorable impact on cognitive impairment across various disorders, primarily by quelling neuroinflammation. However, the precise influence of dietary restriction on perioperative neurocognitive disorders remains to be definitively ascertained. This investigation aims to explore the effects of dietary restriction on perioperative neurocognitive disorders and propose innovative therapeutic strategies for their management. The model of perioperative neurocognitive disorder was induced through exploratory laparotomy under isoflurane anesthesia. Cognitive performance was evaluated using the open field test, Barnes maze test, and fear conditioning test. The enzyme-linked immunosorbent assay (ELISA) was employed to quantify concentrations of interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α) in both serum and hippocampal samples. The Western blot technique was utilized to assess expression levels of hippocampal PSD 95, Synaptophysin, TLR4, MyD88, and NF-kB p65. Microglial polarization was gauged using a combination of reverse transcription quantitative polymerase chain reaction (RT-qPCR) and immunofluorescence labeling techniques. We conducted 16S rRNA sequencing to investigate the impact of dietary restriction on the intestinal flora of aged mice following anesthesia/surgery. Our findings indicate that dietary restrictions have the potential to ameliorate anesthesia/surgery-induced cognitive dysfunction. This effect is achieved through the modulation of gut microbiota, suppression of inflammatory responses in hippocampal microglia, and facilitation of neuronal repair and regeneration.

An immune signature of postoperative cognitive decline in elderly patients

Postoperative cognitive decline (POCD) is the predominant complication affecting elderly patients following major surgery, yet its prediction and prevention remain challenging. Understanding biological processes underlying the pathogenesis of POCD is essential for identifying mechanistic biomarkers to advance diagnostics and therapeutics. This longitudinal study involving 26 elderly patients undergoing orthopedic surgery aimed to characterize the impact of peripheral immune cell responses to surgical trauma on POCD. Trajectory analyses of single-cell mass cytometry data highlighted early JAK/STAT signaling exacerbation and diminished MyD88 signaling post-surgery in patients who developed POCD. Further analyses integrating single-cell and plasma proteomic data collected before surgery with clinical variables yielded a sparse predictive model that accurately identified patients who would develop POCD (AUC = 0.80). The resulting POCD immune signature included one plasma protein and ten immune cell features, offering a concise list of biomarker candidates for developing point-of-care prognostic tests to personalize perioperative management of at-risk patients. The code and the data are documented and available at https://github.com/gregbellan/POCD .

Teaser

Modeling immune cell responses and plasma proteomic data predicts postoperative cognitive decline.

DPP-4 inhibition by linagliptin ameliorates age-related mild cognitive impairment by regulating microglia polarization in mice

Extensive preclinical evidence demonstrates a causative link between insulin signaling dysfunction and the pathogenesis of Alzheimer's disease (AD), and diabetic drugs may represent a promising approach to fighting AD. However, it remains to be determined which antidiabetic drugs are more effective in preventing cognitive impairment. Thus, the present study investigated the effect of dipeptidyl peptidase-4 (DPP-4) inhibitor linagliptin on cognitive impairment in middle-aged mice by comparing it with the effect of metformin. We found that DPP-4 activity increased in the hippocampus of middle-aged mice, and DPP-4 was mainly expressed by microglia rather than astrocytes and oligodendrocytes. DPP-4 directly regulated M1/M2 microglia polarization following LPS or IL-4 stimulation, while DPP-4 inhibitor, linagliptin, suppressed M1-polarized activation and induced M2-polarized activation. Both linagliptin and metformin enhanced cognitive ability, increased hippocampal synaptic plasticity and neurogenesis, and decreased age-related oxidative stress and inflammation by regulating microglia polarization in the hippocampus of middle-aged mice. The combination of linagliptin and metformin showed a maximum protective effect compared to the individual drugs alone. Loss of macrophage inflammatory protein-1α (MIP-1α), a DPP-4 substrate, abrogated the cognitive protection and anti-inflammation effects of linagliptin. Therefore, the current investigation exhibits a potential utility for DPP-4 inhibition in attenuating microglia-mediated inflammation and preventing mild cognitive impairment (MCI) in middle-aged mice, and the effect was partly mediated by MIP-1α.

Update of the European Society of Anaesthesiology and Intensive Care Medicine evidence-based and consensus-based guideline on postoperative delirium in adult patients

Postoperative delirium (POD) remains a common, dangerous and resource-consuming adverse event but is often preventable. The whole peri-operative team can play a key role in its management. This update to the 2017 ESAIC Guideline on the prevention of POD is evidence-based and consensus-based and considers the literature between 01 April 2015, and 28 February 2022. The search terms of the broad literature search were identical to those used in the first version of the guideline published in 2017. POD was defined in accordance with the DSM-5 criteria. POD had to be measured with a validated POD screening tool, at least once per day for at least 3 days starting in the recovery room or postanaesthesia care unit on the day of surgery or, at latest, on postoperative day 1. Recent literature confirmed the pathogenic role of surgery-induced inflammation, and this concept reinforces the positive role of multicomponent strategies aimed to reduce the surgical stress response. Although some putative precipitating risk factors are not modifiable (length of surgery, surgical site), others (such as depth of anaesthesia, appropriate analgesia and haemodynamic stability) are under the control of the anaesthesiologists. Multicomponent preoperative, intra-operative and postoperative preventive measures showed potential to reduce the incidence and duration of POD, confirming the pivotal role of a comprehensive and team-based approach to improve patients' clinical and functional status.

Post-operative cognitive dysfunction is exacerbated by high-fat diet via TLR4 and prevented by dietary DHA supplementation

Post-operative cognitive dysfunction (POCD) is an abrupt decline in neurocognitive function arising shortly after surgery and persisting for weeks to months, increasing the risk of dementia diagnosis. Advanced age, obesity, and comorbidities linked to high-fat diet (HFD) consumption such as diabetes and hypertension have been identified as risk factors for POCD, although underlying mechanisms remain unclear. We have previously shown that surgery alone, or 3-days of HFD can each evoke sufficient neuroinflammation to cause memory deficits in aged, but not young rats. The aim of the present study was to determine if HFD consumption before surgery would potentiate and prolong the subsequent neuroinflammatory response and memory deficits, and if so, to determine the extent to which these effects depend on activation of the innate immune receptor TLR4, which both insults are known to stimulate. Young-adult (3mo) & aged (24mo) male F344xBN F1 rats were fed standard chow or HFD for 3-days immediately before sham surgery or laparotomy. In aged rats, the combination of HFD and surgery caused persistent deficits in contextual memory and cued-fear memory, though it was determined that HFD alone was sufficient to cause the long-lasting cued-fear memory deficits. In young adult rats, HFD + surgery caused only cued-fear memory deficits. Elevated proinflammatory gene expression in the hippocampus of both young and aged rats that received HFD + surgery persisted for at least 3-weeks after surgery. In a separate experiment, rats were administered the TLR4-specific antagonist, LPS-RS, immediately before HFD onset, which ameliorated the HFD + surgery-associated neuroinflammation and memory deficits. Similarly, dietary DHA supplementation for 4 weeks prior to HFD onset blunted the neuroinflammatory response to surgery and prevented development of persistent memory deficits. These results suggest that HFD 1) increases risk of persistent POCD-associated memory impairments following surgery in male rats in 2) a TLR4-dependent manner, which 3) can be targeted by DHA supplementation to mitigate development of persistent POCD.

Postoperative cognitive dysfunction-current research progress

Postoperative cognitive dysfunction (POCD) commonly occurs after surgery, particularly in elderly individuals. It is characterized by a notable decline in cognitive performance, encompassing memory, attention, coordination, orientation, verbal fluency, and executive function. This reduction in cognitive abilities contributes to extended hospital stays and heightened mortality. The prevalence of POCD can reach 40% within 1 week following cardiovascular surgery and remains as high as 17% 3 months post-surgery. Furthermore, POCD exacerbates the long-term risk of Alzheimer's disease (AD). As a result, numerous studies have been conducted to investigate the molecular mechanisms underlying POCD and potential preventive strategies. This article provides a review of the research progress on POCD.

Decoding the Neurological Sequelae of General Anesthesia: A Review

General anesthesia is an integral part of modern surgical practice, but it is associated with a number of complications, including neurological ones. This article provides a thorough analysis of these complications, taking into account the most common ones like drug complications, through delirium, postoperative cognitive impairment (POCD), to the rarest ones like perioperative stroke (POS), spinal cord ischemia (SCI), and postoperative visual loss (POVL). Its main goal is to familiarize healthcare professionals, especially those involved in anesthesiology, with the intricacies of neurological complications. Given their specificity and frequency of occurrence, it is well known that the diagnosis and management of these complications can sometimes cause problems for physicians without advanced neurological knowledge. Also, in addition to complex diagnostics, the pathomechanism of non-pharmacological complications is often not fully understood due to their multifactoriality and sometimes paucity of research. For this reason, an increasing amount of work is being done in the medical community to better understand this group of conditions, enabling faster diagnosis and more effective treatment, as well as perioperative prevention. This paper aims to increase awareness and vigilance among physicians across the spectrum of surgical patient care, from premedication to postoperative follow-up. Drawing on the authors' experience and the extensive medical literature, this paper includes 39 selected articles from 1994 to 2023, seeking the latest insights in the constantly evolving field of neurology and anesthesiology. This article aims to review the neurological complications of general anesthesia.

The P38MAPK/ATF2 signaling pathway is involved in PND in mice

Accumulating evidence indicates that microglia-mediated neuroinflammation in the hippocampus contributes to the development of perioperative neurocognitive disorder (PND). P38MAPK, a point of convergence for different signaling processes involved in inflammation, can be activated by various stresses. This study aims to investigate the role of the P38MAPK/ATF2 signaling pathway in the development of PND in mice. Aged C57BL/6 mice were subjected to tibial fracture surgery under isoflurane anesthesia to establish a PND animal model. The open field test was used to evaluate the locomotor activity of the mice. Neurocognitive function was assessed with the Morris water maze (MWM) and fear conditioning test (FCT) on postoperative days 1, 3 and 7. The mice exhibited cognitive impairment accompanied by increased expression of proinflammatory factors (IL-1β, TNF-α), proapoptotic molecules (caspase-3, bax) and microglial activation in the hippocampus 1, 3 and 7 days after surgery. Treatment with SB239063 (a P38MAPK inhibitor) decreased the expression of proinflammatory factors, proapoptotic molecules and Iba-1 in the CA1 region of the hippocampus. The number of surviving neurons was significantly increased. Inhibition of the P38MAPK/ATF2 signaling pathway attenuates hippocampal neuroinflammation and neuronal apoptosis in aged mice with PND, thus improving the perioperative cognitive function of the mice.

J147 affects cognition and anxiety after surgery in Zucker rats

Vulnerable patients are at risk for neuroinflammation-mediated post-operative complications, including depression (POD) and cognitive dysfunction (POCD). Zucker rats, expressing multiple risk factors for post-operative complications in humans, may provide a clinically relevant model to study pathophysiology and explore potential interventions. J147, a newly developed anti-dementia drug, was shown to prevent POCD in young healthy rats, and improved early post-surgical recovery in Zucker rats. Aim of the present study was to investigate POCD and the therapeutic potential of J147 in male Zucker rats. Risk factors in the Zucker rat strain were evaluated by comparison with lean littermates. Zucker rats were subjected to major abdominal surgery. Acute J147 treatment was provided by a single iv injection (10 mg/kg) at the start of surgery, while chronic J147 treatment was provided in the food (aimed at 30 mg/kg/day), starting one week before surgery and up to end of protocol. Effects on behavior were assessed, and plasma, urine and brain tissue were collected and processed for immunohistochemistry and molecular analyses. Indeed, Zucker rats displayed increased risk factors for POCD, including obesity, high plasma triglycerides, low grade systemic inflammation, impaired spatial learning and decreased neurogenesis. Surgery in Zucker rats reduced exploration and increased anxiety in the Open Field test, impaired short-term spatial memory, induced a shift in circadian rhythm and increased plasma neutrophil gelatinase-associated lipocalin (NGAL), microglia activity in the CA1 and blood brain barrier leakage. Chronic, but not acute J147 treatment reduced anxiety in the Open Field test and protected against the spatial memory decline. Moreover, chronic J147 increased glucose sensitivity. Acute J147 treatment improved long-term spatial memory and reversed the circadian rhythm shift. No anti-inflammatory effects were seen for J147. Although Zucker rats displayed risk factors, surgery did not induce extensive POCD. However, increased anxiety may indicate POD. Treatment with J147 showed positive effects on behavioral and metabolic parameters, but did not affect (neuro)inflammation. The mixed effect of acute and chronic treatment may suggest a combination for optimal treatment.

Bridging the Gap: Investigating the Link between Inflammasomes and Postoperative Cognitive Dysfunction

Postoperative cognitive dysfunction (POCD) is a cluster of cognitive problems that may arise after surgery. POCD symptoms include memory loss, focus inattention, and communication difficulties. Inflammasomes, intracellular multiprotein complexes that control inflammation, may have a significant role in the development of POCD. It has been postulated that the NLRP3 inflammasome promotes cognitive impairment by triggering the inflammatory response in the brain. Nevertheless, there are many gaps in the current literature to understand the underlying pathophysiological mechanisms and develop future therapy. This review article underlines the limits of our current knowledge about the NLRP3 (NOD-, LRR- and pyrin domain-containing protein 3) inflammasome and POCD. We first discuss inflammasomes and their types, structures, and functions, then summarize recent evidence of the NLRP3 inflammasome's involvement in POCD. Next, we propose a hypothesis that suggests the involvement of inflammasomes in multiple organs, including local surgical sites, blood circulation, and other peripheral organs, leading to systemic inflammation and subsequent neuronal dysfunction in the brain, resulting in POCD. Research directions are then discussed, including analyses of inflammasomes in more clinical POCD animal models and clinical trials, studies of inflammasome types that are involved in POCD, and investigations into whether inflammasomes occur at the surgical site, in circulating blood, and in peripheral organs. Finally, we discuss the potential benefits of using new technologies and approaches to study inflammasomes in POCD. A thorough investigation of inflammasomes in POCD might substantially affect clinical practice.

Neuroinflammation: The central enabler of postoperative cognitive dysfunction

The proportion of advanced age patients undergoing surgical procedures is on the rise owing to advancements in surgical and anesthesia technologies as well as an overall aging population. As a complication of anesthesia and surgery, older patients frequently suffer from postoperative cognitive dysfunction (POCD), which may persist for weeks, months or even longer. POCD is a complex pathological process involving multiple pathogenic factors, and its mechanism is yet unclear. Potential theories include inflammation, deposition of pathogenic proteins, imbalance of neurotransmitters, and chronic stress. The identification, prevention, and treatment of POCD are still in the exploratory stages owing to the absence of standardized diagnostic criteria. Undoubtedly, comprehending the development of POCD remains crucial in overcoming the illness. Neuroinflammation is the leading hypothesis and a crucial component of the pathological network of POCD and may have complex interactions with other mechanisms. In this review, we discuss the possible ways in which surgery and anesthesia cause neuroinflammation and investigate the connection between neuroinflammation and the development of POCD. Understanding these mechanisms may likely ensure that future treatment options of POCD are more effective.

Immunity impacts cognitive deficits across neurological disorders

Cognitive deficits are a common comorbidity with neurological disorders and normal aging. Inflammation is associated with multiple diseases including classical neurodegenerative dementias such as Alzheimer's disease (AD) and autoimmune disorders such as multiple sclerosis (MS), in which over half of all patients experience some form of cognitive deficits. Other degenerative diseases of the central nervous system (CNS) including frontotemporal lobe dementia (FTLD), and Parkinson's disease (PD) as well as traumatic brain injury (TBI) and psychological disorders like major depressive disorder (MDD), and even normal aging all have cytokine-associated reductions in cognitive function. Thus, there is likely commonality between these secondary cognitive deficits and inflammation. Neurological disorders are increasingly associated with substantial neuroinflammation, in which CNS-resident cells secrete cytokines and chemokines such as tumor necrosis factor (TNF)α and interleukins (ILs) including IL-1β and IL-6. CNS-resident cells also respond to a wide variety of cytokines and chemokines, which can have both direct effects on neurons by changing the expression of ion channels and perturbing electrical properties, as well as indirect effects through glia-glia and immune-glia cross-talk. There is significant overlap in these cytokine and chemokine expression profiles across diseases, with TNFα and IL-6 strongly associated with cognitive deficits in multiple disorders. Here, we review the involvement of various cytokines and chemokines in AD, MS, FTLD, PD, TBI, MDD, and normal aging in the absence of dementia. We propose that the neuropsychiatric phenotypes observed in these disorders may be at least partially attributable to a dysregulation of immunity resulting in pathological cytokine and chemokine expression from both CNS-resident and non-resident cells.

Inhibition of adult hippocampal neurogenesis induced by postoperative CD8 + T-cell infiltration is associated with cognitive decline later following surgery in adult mice

BACKGROUND

Some patients show persistent cognitive decline for weeks, months or even years after surgery, which seriously affects their long-term prognosis and quality of life. However, most previous basic studies have focused mainly on the mechanisms of early postoperative cognitive decline, whereas cognitive decline in the longer term after surgery is less well-understood. The subgranular zone of the dentate gyrus exhibits life-long neurogenesis, supporting hippocampus-dependent learning and memory.

MAIN TEXT

The aim of this study was to investigate whether adult hippocampal neurogenesis (AHN) involves in cognitive decline later following surgery and to further explore the roles of CD8 + T lymphocytes infiltrating the hippocampal parenchyma after surgery in this pathological process. Cognitive function was examined in adult mice that underwent laparotomy combined with partial hepatectomy, and the results showed that cognitive decline persisted in mice who underwent surgery during the first postoperative month, even though there was a trend toward continuous improvement over time. Significantly decreased numbers of DCX + cells, BrdU + cells, and BrdU + /DCX + cells were observed on day 8 after surgery, and a significantly decreased number of NeuN + /BrdU + cells was observed on day 28 after surgery, which indicated inhibition of AHN. After surgery, T lymphocytes, the majority of which were CD8 + T cells, infiltrated the hippocampus and secreted Interferon-γ (IFN-γ). Depletion of CD8 + T cells could inhibit the increase of IFN-γ synthesis, improve hippocampal neurogenesis, and improve postoperative cognitive function. Hippocampal microinjection of IFN-γ neutralizing antibody or adeno-associated virus to knock down IFN-γ receptor 1 (IFNGR1) could also partially attenuate the inhibition of AHN and improve postoperative cognitive function.

CONCLUSIONS

These results demonstrate that postoperative infiltration of CD8 + T cells into the hippocampus and subsequent secretion of IFN-γ contribute to the inhibition of AHN and cognitive decline later following surgery.

TAK1 Reduces Surgery-induced Overactivation of RIPK1 to Relieve Neuroinflammation and Cognitive Dysfunction in Aged Rats

BACKGROUND

Postoperative cognitive dysfunction (POCD) is a common clinical complication in elderly patients, but its underlying mechanism remains unclear. Receptor-interacting protein kinase 1 (RIPK1), a key molecule mediating necroptosis and regulated by transforming growth factor β-activated kinase 1 (TAK1), was reported to be associated with cognitive impairment in several neurodegenerative diseases. This study was conducted to investigate the possible role of TAK1/RIPK1 signalling in POCD development following surgery in rats.

METHODS

Young (2-month-old) and old (24-month-old) Sprague-Dawley rats were subjected to splenectomy under isoflurane anaesthesia. The young rats were treated with the TAK1 inhibitor takinib or the RIPK1 inhibitor necrostatin-1 (Nec-1) before surgery, and old rats received adeno-associated virus (AAV)-TAK1 before surgery. The open field test and contextual fear conditioning test were conducted on postoperative day 3. The changes in TNF-α, pro-IL-1β, AP-1, NF-κB p65, pRIPK1, pTAK1 and TAK1 expression and astrocyte and microglia activation in the hippocampus were assessed.

RESULTS

Old rats had low TAK1 expression and were more susceptible to surgery-induced POCD and neuroinflammation than young rats. TAK1 inhibition exacerbated surgery-induced pRIPK1 expression, neuroinflammation and cognitive dysfunction in young rats, and this effect was reversed by a RIPK1 inhibitor. Conversely, genetic TAK1 overexpression attenuated surgery-induced pRIPK1 expression, neuroinflammation and cognitive dysfunction in old rats.

CONCLUSION

Ageing-related decreases in TAK1 expression may contribute to surgery-induced RIPK1 overactivation, resulting in neuroinflammation and cognitive impairment in old rats.

Postoperative Learning and Memory Dysfunction Is More Severe in Males But Is Not Persistent and Transmittable to Next Generation in Young Adult Rats

BACKGROUND

Postoperative cognitive dysfunction (POCD) affects numerous patients each year and is associated with poor outcomes. Currently, the duration of POCD is not known. This preclinical study determined whether POCD was persistent, different between sexes and transmittable to the next generation.

METHODS

Two-month-old Sprague-Dawley rats had left carotid artery exposure under isoflurane anesthesia and their learning and memory were assessed from 5 days, 2 months, and 4 months after surgery. Rats with or without surgery were mated when they were 4 or 6 months old, and the learning and memory of the offspring were tested at 2 months of age.

RESULTS

Males exposed to surgery took a longer time to identify the target box after training sessions in a Barnes maze and had less freezing behavior in context-related fear conditioning than control rats when the tests were started 5 days after surgery. Similarly, female rats had a poorer performance than control rats in the Barnes maze test from 5 days after surgery. However, these poorer performances were not observed when the tests were administered 2 or 4 months after surgery. The offspring of rats with surgery had a performance similar to that of the offspring of control rats.

CONCLUSIONS

Our results suggest that both male and female rats develop POCD but that the learning and memory dysfunction appears to be more severe in male rats. POCD may not be persistent and does not transmit to the next generation.

Human umbilical cord-derived mesenchymal stem cells ameliorate perioperative neurocognitive disorder by inhibiting inflammatory responses and activating BDNF/TrkB/CREB signaling pathway in aged mice

BACKGROUND

Perioperative neurocognitive disorder (PND) is a key complication affecting older individuals after anesthesia and surgery. Failure to translate multiple pharmacological therapies for PND from preclinical studies to clinical settings has necessitated the exploration of novel therapeutic strategies. Human umbilical cord-derived mesenchymal stem cells (hUC-MSCs) treatment has emerged as a promising therapeutic strategy for treating neurodegenerative diseases and has the potential to translate basic science into clinical practice. In this study, we investigated the effects and underlying mechanism of hUC-MSCs on PND in aged mice.

METHODS

hUC-MSCs were isolated from an infant umbilical cord and identified using flow cytometry and differentiation assays. We established PND model by undergoing aseptic laparotomy under isoflurane anesthesia maintaining spontaneous ventilation in eighteen-month-old male C57BL/6 mice. hUC-MSCs were slowly injected into mice by coccygeal vein before anesthesia. Cognitive function, systemic and neuroinflammatory responses, neuroplasticity, endogenous neurogenesis, and brain-derived neurotrophic factor (BDNF) were assessed. To determine the brain mechanisms underlying by which hUC-MSCs mediate their neuroprotective effects in PND, K252a, an antagonist of BDNF receptor, was administered intraperitoneally before surgery. Hippocampal BDNF/TrkB/CREB signaling pathway and metabolomic signatures were evaluated.

RESULTS

hUC-MSC treatment ameliorated the learning and memory impairment in aged mice with PND. The downstream effects were the suppression of systemic and hippocampal inflammation and restoration of neurogenesis and neuroplasticity dysregulation. Interestingly, the level of mature BDNF, but not that of proBDNF, was increased in the hippocampus after hUC-MSC treatment. Further analysis revealed that the improved cognitive recovery and the restoration of neurogenesis and neuroplasticity dysregulation elicited by exposure to hUC-MSCs were, at least partially, mediated by the activation of the BDNF/TrkB/CREB signaling pathway. Untargeted metabolomic further identified lipid metabolism dysfunction as potential downstream of the BDNF/TrkB/CREB signaling pathway in hUC-MSC-mediated neuroprotection for PND.

CONCLUSIONS

Our study highlights the beneficial effects of hUC-MSC treatment on PND and provides a justification to consider the potential use of hUC-MSCs in the perioperative period.

Towards experimental models of delirium utilizing zebrafish

Delirium is an acute neuropsychiatric condition characterized by impaired behavior and cognition. Although the syndrome has been known for millennia, its CNS mechanisms and risk factors remain poorly understood. Experimental animal models, especially rodent-based, are commonly used to probe various pathogenetic aspects of delirium. Complementing rodents, the zebrafish (Danio rerio) emerges as a promising novel model organism to study delirium. Zebrafish demonstrate high genetic and physiological homology to mammals, easy maintenance, robust behaviors in various sensitive behavioral tests, and the potential to screen for pharmacological agents relevant to delirium. Here, we critically discuss recent developments in the field, and emphasize the developing utility of zebrafish models for translational studies of delirium and deliriant drugs. Overall, the zebrafish represents a valuable and promising aquatic model species whose use may help understand delirium etiology, as well as develop novel therapies for this severely debilitating disorder.

Systemic inflammation, neuroinflammation and perioperative neurocognitive disorders

Perioperative neurocognitive disorder (PND) is a common disorder following anesthesia and surgery, especially in the elderly. The complex cellular and molecular processes are involved in PND, but the underlying pathogenesis of which remains inconclusive due to conflicting data. A growing body of evidence has been shown that perioperative systemic inflammation plays important roles in the development of PND. We reviewed the relevant literature retrieved by a search in the PubMed database (on July 20, 2023). The search terms used were "delirium", "post operative cognitive dysfunction", "perioperative neurocognitive disorder", "inflammation" and "systemic", alone and in combination. All articles identified were English-language, full-text papers. The ones cited in the review are those that make a substantial contribution to the knowledge about systemic inflammation and PNDs. The aim of this review is to bring together the latest evidence for the understanding of how perioperative systemic inflammation mediates neuroinflammation and brain injury, how the inflammation is regulated and how we can translate these findings into prevention and/or treatment for PND.

Systemic inflammation induced from remote extremity trauma is a critical driver of secondary brain injury

Blast exposure, commonly experienced by military personnel, can cause devastating life-threatening polysystem trauma. Despite considerable research efforts, the impact of the systemic inflammatory response after major trauma on secondary brain injury-inflammation is largely unknown. The aim of this study was to identify markers underlying the susceptibility and early onset of neuroinflammation in three rat trauma models: (1) blast overpressure exposure (BOP), (2) complex extremity trauma (CET) involving femur fracture, crush injury, tourniquet-induced ischemia, and transfemoral amputation through the fracture site, and (3) BOP+CET. Six hours post-injury, intact brains were harvested and dissected to obtain biopsies from the prefrontal cortex, striatum, neocortex, hippocampus, amygdala, thalamus, hypothalamus, and cerebellum. Custom low-density microarray datasets were used to identify, interpret and visualize genes significant (p < 0.05 for differential expression [DEGs]; 86 neuroinflammation-associated) using a custom python-based computer program, principal component analysis, heatmaps and volcano plots. Gene set and pathway enrichment analyses of the DEGs was performed using R and STRING for protein-protein interaction (PPI) to identify and explore key genes and signaling networks. Transcript profiles were similar across all regions in naïve brains with similar expression levels involving neurotransmission and transcription functions and undetectable to low-levels of inflammation-related mediators. Trauma-induced neuroinflammation across all anatomical brain regions correlated with injury severity (BOP+CET > CET > BOP). The most pronounced differences in neuroinflammatory-neurodegenerative gene regulation were between blast-associated trauma (BOP, BOP+CET) and CET. Following BOP, there were few DEGs detected amongst all 8 brain regions, most were related to cytokines/chemokines and chemokine receptors, where PPI analysis revealed Il1b as a potential central hub gene. In contrast, CET led to a more excessive and diverse pro-neuroinflammatory reaction in which Il6 was identified as the central hub gene. Analysis of the of the BOP+CET dataset, revealed a more global heightened response (Cxcr2, Il1b, and Il6) as well as the expression of additional functional regulatory networks/hub genes (Ccl2, Ccl3, and Ccl4) which are known to play a critical role in the rapid recruitment and activation of immune cells via chemokine/cytokine signaling. These findings provide a foundation for discerning pathophysiological consequences of acute extremity injury and systemic inflammation following various forms of trauma in the brain.

Formyl peptide receptor 1 is involved in surgery-induced neuroinflammation and dysfunction of learning and memory in mice

Postoperative cognitive dysfunction (POCD) is a common complication after surgery. Peripheral immune cells may contribute to the development of POCD. However, molecules that are important for this contribution are not known. We hypothesize that formyl peptide receptor 1 (FPR1), a molecule critical for the migration of the monocytes and neutrophils into the brain after brain ischemia, is central to the development of postoperative neuroinflammation and dysfunction of learning and memory. Male C57BL/6 (wild-type) mice and FPR1-/- mice received right carotid artery exposure surgery. Some wild-type mice received cFLFLF, an FPR1 antagonist. Mouse brains were harvested 24 h after the surgery for biochemical analysis. Mice were subjected to the Barnes maze and fear conditioning tests to determine their learning and memory from 2 weeks after the surgery. We found that surgery increased FPR1 in the brain and proinflammatory cytokines in the blood and brain of wild-type mice. Surgery also impaired their learning and memory. cFLFLF attenuated these effects. Surgery did not induce an increase in the proinflammatory cytokines and impairment of learning and memory in FPR1-/- mice. These results suggest that FPR1 is important for the development of neuroinflammation and dysfunction of learning and memory after surgery. Specific interventions that inhibit FPR1 may be developed to reduce POCD.

New advances in clinical application of neostigmine: no longer focusing solely on increasing skeletal muscle strength

Neostigmine is a clinical cholinesterase inhibitor, that is, commonly used to enhance the function of the cholinergic neuromuscular junction. Recent studies have shown that neostigmine regulates the immune-inflammatory response through the cholinergic anti-inflammatory pathway, affecting perioperative neurocognitive function. This article reviews the relevant research evidence over the past 20 years, intending to provide new perspectives and strategies for the clinical application of neostigmine.

Transversus thoracic muscle plane block for pain during cardiac surgery: a systematic review and meta-analysis

STUDY OBJECTIVE

The role of transversus thoracic muscle plane blocks (TTMPBs) during cardiac surgery is controversial. We conducted a systematic review to establish the effectiveness of this procedure.

DESIGN

Systematic review. We searched PubMed, Embase, Web of Science, CENTRAL, WanFang Data, and the China National Knowledge Infrastructure to June 2022, and followed the GRADE approach to evaluate the certainty of evidence.

STUDY ELIGIBILITY CRITERIA

Eligible studies enrolled adult patients scheduled to undergo cardiac surgery and randomized them to receive a TTMPB or no block/sham block.

MAIN RESULTS

Nine trials that enrolled 454 participants were included. Compared to no block/sham block, moderate certainty evidence found that TTMPB probably reduces postoperative pain at rest at 12 h [weighted mean difference (WMD) -1.51 cm on a 10 cm visual analogue scale for pain, 95% CI -2.02 to -1.00; risk difference (RD) for achieving mild pain or less (≤3 cm), 41%, 95% CI 17-65) and 24 h (WMD -1.07 cm, 95% CI -1.83 to -0.32; RD 26%, 95% CI 9-37). Moderate certainty evidence also supported that TTMPB probably reduces pain during movement at 12 h (WMD -3.42 cm, 95% CI -4.47 to -2.37; RD 46%, 95% CI 12-80) and at 24 h (WMD -1.73 cm, 95% CI -3.24 to -0.21; RD 32%, 95% CI 5-59), intraoperative opioid use [WMD -28 milligram morphine equivalent (MME), 95% CI -42 to -15], postoperative opioid consumption (WMD -17 MME, 95% CI -29 to -5), postoperative nausea and vomiting (absolute risk difference 255 less per 1000 persons, 95% CI 140-314), and intensive care unit (ICU) length of stay (WMD -13 h, 95% CI -21 to -6).

CONCLUSION

Moderate certainty evidence showed TTMPB during cardiac surgery probably reduces postoperative pain at rest and with movement, opioid consumption, ICU length of stay, and the incidence of nausea and vomiting.

Two parallel medial prefrontal cortex-amygdala pathways mediate memory deficits via glutamatergic projection in surgery mice

The neural circuit mechanisms underlying postoperative cognitive dysfunction (POCD) remain elusive. We hypothesized that projections from the medial prefrontal cortex (mPFC) to the amygdala are involved in POCD. A mouse model of POCD in which isoflurane (1.5%) combined with laparotomy was used. Virally assisted tracing techniques were used to label the relevant pathways. Fear conditioning, immunofluorescence, whole-cell patch-clamp recordings, and chemogenetic and optogenetic techniques were applied to investigate the role of mPFC-amygdala projections in POCD. We find that surgery impairs memory consolidation but not retrieval of consolidated memories. In POCD mice, the glutamatergic pathway from the prelimbic cortex to the basolateral amygdala (PL-BLA) shows reduced activity, whereas the glutamatergic pathway from the infralimbic cortex to the basomedial amygdala (IL-BMA) shows enhanced activity. Our study indicates that the hypoactivity in the PL-BLA pathway interrupts memory consolidation, whereas the hyperactivity in the IL-BMA promotes memory extinction, in POCD mice.

The role of peripheral inflammatory insults in Alzheimer's disease: a review and research roadmap

Peripheral inflammation, defined as inflammation that occurs outside the central nervous system, is an age-related phenomenon that has been identified as a risk factor for Alzheimer's disease. While the role of chronic peripheral inflammation has been well characterized in the context of dementia and other age-related conditions, less is known about the neurologic contribution of acute inflammatory insults that take place outside the central nervous system. Herein, we define acute inflammatory insults as an immune challenge in the form of pathogen exposure (e.g., viral infection) or tissue damage (e.g., surgery) that causes a large, yet time-limited, inflammatory response. We provide an overview of the clinical and translational research that has examined the connection between acute inflammatory insults and Alzheimer's disease, focusing on three categories of peripheral inflammatory insults that have received considerable attention in recent years: acute infection, critical illness, and surgery. Additionally, we review immune and neurobiological mechanisms which facilitate the neural response to acute inflammation and discuss the potential role of the blood-brain barrier and other components of the neuro-immune axis in Alzheimer's disease. After highlighting the knowledge gaps in this area of research, we propose a roadmap to address methodological challenges, suboptimal study design, and paucity of transdisciplinary research efforts that have thus far limited our understanding of how pathogen- and damage-mediated inflammatory insults may contribute to Alzheimer's disease. Finally, we discuss how therapeutic approaches designed to promote the resolution of inflammation may be used following acute inflammatory insults to preserve brain health and limit progression of neurodegenerative pathology.

Odor Enrichment Attenuates the Anesthesia/Surgery-induced Cognitive Impairment

OBJECTIVE

To determine the association between olfactory function and cognition in patients and rodents.

BACKGROUND

Perioperative neurocognitive disorders include delayed neurocognitive recovery (dNCR). The contribution of olfactory function to dNCR remains undetermined. It is unknown whether odor enrichment could mitigate dNCR.

METHODS

We performed a prospective observational cohort study to determine potential association between olfactory impairment and dNCR in patients. We assessed the effects of anesthesia/surgery on olfactory and cognitive function in mice using the block test and Barnes maze. We measured interleukin-6 (IL-6), olfactory mature protein, growth-associated protein 43, mature and premature olfactory neurons, postsynaptic density 95, and synaptophysin in blood, nasal epithelium, and hippocampus of mice. Odor enrichment, IL-6 antibody, and knockout of IL-6 were used in the interaction experiments.

RESULTS

Patients with dNCR had worse odor identification than the patients without dNCR [preoperative: 7 (1.25, 9) vs 10 (8, 11), median (interquartile range), P <0.001; postoperative: 8 (2.25, 10) vs 10 (8, 11), P <0.001]. Olfactory impairment associated with dNCR in patients before and after adjusting age, sex, education, preoperative mini-mental state examination score, and days of the neuropsychological tests. Anesthesia/surgery induced olfactory and cognitive impairment, increased levels of IL-6 in blood and nasal epithelium, decreased amounts of olfactory receptor neurons and their markers in the nasal epithelium, and reduced amounts of synapse markers in the hippocampus of mice. These changes were attenuated by odor enrichment and IL-6 antibody.

CONCLUSION

The anesthesia/surgery-induced olfactory impairment may contribute to dNCR in patients and postoperative cognitive impairment in mice. Odor enrichment could be a potential intervention.

Prior exposure to stress exacerbates neuroinflammation and causes long-term behavior changes in sepsis

Background

Neuroinflammation can occur during sepsis and is now regarded as the main mechanism underlying various related central nervous system (CNS) disorders. Another well-known factor causing neuroinflammation is psychological stress. In the current study, we examined the effects of prior exposure to stress on sepsis-induced neuroinflammation and CNS symptoms.

Experimental procedure

Balb/c mice were subjected to wet bedding stress for 2 days, then lipopolysaccharide (LPS) was intraperitoneally administered. For examining the neuroinflammation, the expression of proinflammatory cytokines and NF-κB activity in the brain was analyzed by RT-PCR and ELISA-based assay. Additionally, immunohistochemical study using Iba-1 was performed. Finally, behavior tests were examined one month after LPS treatment.

Result and conclusion

Stress exposure induced the upregulation of IL-1β, IL-6 and TNFα mRNA in the cerebral cortex 4 h after LPS administration. Suggesting an underlying mechanism, LPS-induced NF-κB activation was significantly upregulated with stress in the brain. Histologically, microglia in the cerebral cortex were reactive and became more abundant with stress, while these effects were further increased with LPS injection. Behavioral analysis conducted showed a significant increase of anxiety-like behaviors in the stressed mice. These results suggest that prior exposure to stress exacerbates neuroinflammation during sepsis and induces long-term behavior changes.

β-arrestin1 regulates astrocytic reactivity via Drp1-dependent mitochondrial fission: implications in postoperative delirium

Postoperative delirium (POD) is a frequent and debilitating complication, especially amongst high risk procedures, such as orthopedic surgery. This kind of neurocognitive disorder negatively affects cognitive domains, such as memory, awareness, attention, and concentration after surgery; however, its pathophysiology remains unknown. Multiple lines of evidence supporting the occurrence of inflammatory events have come forward from studies in human patients' brain and bio-fluids (CSF and serum), as well as in animal models for POD. β-arrestins are downstream molecules of guanine nucleotide-binding protein (G protein)-coupled receptors (GPCRs). As versatile proteins, they regulate numerous pathophysiological processes of inflammatory diseases by scaffolding with inflammation-linked partners. Here we report that β-arrestin1, one type of β-arrestins, decreases significantly in the reactive astrocytes of a mouse model for POD. Using β-arrestin1 knockout (KO) mice, we find aggravating effect of β-arrestin1 deficiency on the cognitive dysfunctions and inflammatory phenotype of astrocytes in POD model mice. We conduct the in vitro experiments to investigate the regulatory roles of β-arrestin1 and demonstrate that β-arrestin1 in astrocytes interacts with the dynamin-related protein 1 (Drp1) to regulate mitochondrial fusion/fission process. β-arrestin1 deletion cancels the combination of β-arrestin1 and cellular Drp1, thus promoting the translocation of Drp1 to mitochondrial membrane to provoke the mitochondrial fragments and the subsequent mitochondrial malfunctions. Using β-arrestin1-biased agonist, cognitive dysfunctions of POD mice and pathogenic activation of astrocytes in the POD-linked brain region are reduced. We, therefore, conclude that β-arrestin1 is a promising target for the understanding of POD pathology and development of POD therapeutics.

Adiponectin Attenuates Splenectomy-Induced Cognitive Deficits by Neuroinflammation and Oxidative Stress via TLR4/MyD88/NF-κb Signaling Pathway in Aged Rats

Perioperative neurocognitive disorder (PND) is a common adverse event after surgical trauma in elderly patients. The pathogenesis of PND is still unclear. Adiponectin (APN) is a plasma protein secreted by adipose tissue. We have reported that a decreased APN expression is associated with PND patients. APN may be a promising therapeutic agent for PND. However, the neuroprotective mechanism of APN in PND is still unclear. In this study, 18 month old male Sprague-Dawley rats were assigned to six groups: the sham, sham + APN (intragastric (i.g.) administration of 10 μg/kg/day for 20 days before splenectomy), PND (splenectomy), PND + APN, PND + TAK-242 (intraperitoneal (i.p.) administration of 3 mg/kg TAK-242), and PND + APN + lipopolysaccharide (LPS) (i.p. administration of 2 mg/kg LPS). We first found that APN gastric infusion significantly improved learning and cognitive function in the Morris water maze (MWM) test after surgical trauma. Further experiments indicated that APN could inhibit the Toll-like receptor 4 (TLR4)/myeloid differentiation factor 88 (MyD88)/nuclear factor kappa B (NF-κb) p65 pathway to decrease the degree of oxidative damage (malondialdehyde (MDA) and superoxide dismutase (SOD)), microglia-mediated neuroinflammation (ionized calcium binding adapter molecule 1 (IBA1), caspase-1, tumor necrosis factor (TNF)-α, interleukin-1β (IL-1β), and interleukin-6 (IL-6)), and apoptosis (p53, Bcl2, Bax, and caspase 3) in hippocampus. By using LPS-specific agonist and TAK-242-specific inhibitor, the involvement of TLR4 engagement was confirmed. APN intragastric administration exerts a neuroprotective effect against cognitive deficits induced by peripheral trauma, and the possible mechanisms include the inhibition of neuroinflammation, oxidative stress, and apoptosis, mediated by the suppression of the TLR4/MyD88/NF-κb signaling pathway. We propose that oral APN may be a promising candidate for PND treatment.

Acupuncture-related techniques for postoperative cognitive complications: a systemic review and meta-analysis

BACKGROUND

Postoperative cognitive complications are major challenges for postoperative recovery. Acupuncture-related techniques have been used for treating neurocognitive dysfunctions. However, whether they help to prevent postoperative cognitive complicationss remains unclear. We intend to evaluate the effect of acupuncture-related techniques on the incidence of postoperative cognitive complications (PCC) in patients undergoing surgery under general anesthesia.

METHODS

Based on PRISMA guidelines, a search of PubMed, EMBASE, Web of Science, and the Cochrane Central Register of Controlled Trials and ClinicalTrials.gov was performed to identify eligible trials published from inception to June 6, 2021. The search was performed in June 2021. The inclusion criteria were prospective, randomized, controlled clinical trials that compared acupuncture-related techniques with other techniques or non-acupuncture treatment in patients undergoing surgery under general anesthesia. Pooled odds ratios (ORs), 95% CIs, and P values were estimated for end points using fixed and random effects statistical models.

RESULTS

The analysis included 12 studies with 1058 patients. Compared with patients not receiving acupuncture, patients treated with acupuncture-related techniques had a lower incidence of PCCs (OR, 0.44; 95% CI, 0.33 to 0.59; P < 0.001; n = 968) and lower levels of biomarkers, including IL-6, TNF-α, and S100β. Acupuncture with needles and without needles showed similar effects on the prevention of PCCs. The effects of acupuncture-related techniques on PCCs were observed in both English and non-English articles. Subgroup analyses showed that both agitation and/or delirium (OR, 0.51; 95% CI, 0.34 to 0.76; P < 0.001; n = 490) and delayed cognitive recovery (OR, 0.33; 95% CI, 0.21 to 0.51; P < 0.001; n = 478) were reduced after treatment with acupuncture-related techniques. In adult studies evaluating MMSE scores, the scores were not different between groups (SMD, - 0.71; 95% CI, - 1.72 to 0.3; P = 0.17; n = 441).

CONCLUSIONS

Acupuncture-related techniques, including needle techniques and electrical techniques, are associated with fewer postoperative cognitive complications, suggesting that acupuncture could be considered a potential option in the perioperative setting. Additional research is needed to develop higher-quality evidence and optimal regimens.

TRIAL REGISTRATION

PROSPERO (CRD42021258378).

Intergenerational Perioperative Neurocognitive Disorder

Accelerated neurocognitive decline after general anesthesia/surgery, also known as perioperative neurocognitive disorder (PND), is a widely recognized public health problem that may affect millions of patients each year. Advanced age, with its increasing prevalence of heightened stress, inflammation, and neurodegenerative alterations, is a consistent contributing factor to the development of PND. Although a strong homeostatic reserve in young adults makes them more resilient to PND, animal data suggest that young adults with pathophysiological conditions characterized by excessive stress and inflammation may be vulnerable to PND, and this altered phenotype may be passed to future offspring (intergenerational PND). The purpose of this narrative review of data in the literature and the authors' own experimental findings in rodents is to draw attention to the possibility of intergenerational PND, a new phenomenon which, if confirmed in humans, may unravel a big new population that may be affected by parental PND. In particular, we discuss the roles of stress, inflammation, and epigenetic alterations in the development of PND. We also discuss experimental findings that demonstrate the effects of surgery, traumatic brain injury, and the general anesthetic sevoflurane that interact to induce persistent dysregulation of the stress response system, inflammation markers, and behavior in young adult male rats and in their future offspring who have neither trauma nor anesthetic exposure (i.e., an animal model of intergenerational PND).

Long non-coding RNA MEG3 alleviates postoperative cognitive dysfunction by suppressing inflammatory response and oxidative stress via has-miR-106a-5p/SIRT3

Postoperative cognitive dysfunction (POCD), a neurological complication after surgery, is common among the elderly in particular. Maternal expression gene 3 (MEG3) is a novel long non-coding RNA (lncRNA) that contributes to glial cell activation and inflammation. We aim to further explore its role in POCD. Mice were induced with sevoflurane anesthesia and underwent orthopedic surgery to establish a POCD model. BV-2 microglia activation was induced by lipopolysaccharide. The overexpressed lentiviral plasmid lv-MEG3 and its control were injected into mice. pcDNA3.1-MEG3, has-miR-106a-5p mimic, and its negative control were transfected into BV-2 cells. The expressions of has-miR-106a-5p MEG3 and Sirtuin 3 (SIRT3) in rat hippocampus and BV-2 cells were quantitatively detected. Levels of SIRT3, TNF-α, and IL-1β were detected by western blot, levels of TNF-α and IL-1β by ELISA, and expression of GSH-Px, SOD, and MDA by kits. The targeting relationship between MEG3 and has-miR-106a-5p was confirmed using bioinformatics and dual-luciferase reporter assay. LncRNA MEG3 was down-regulated in POCD mice, whereas has-miR-106a-5 levels were up-regulated. Overexpression of MEG3 could attenuate cognitive dysfunction and inflammatory response in POCD mice, inhibit lipopolysaccharide-induced inflammatory response and oxidative stress in BV-2 cells, and promote has-miR-106a through competitive binding with has-miR-106a-5-5 expression of target gene SIRT3. Overexpression of has-miR-106a-5p had a reverse effect on overexpression of MEG3 functioning on lipopolysaccharide-induced BV-2 cells. LncRNA MEG3 could inhibit the inflammatory response and oxidative stress via has-miR-106a-5p/SIRT3, thereby reducing POCD, which might be a potential biological target for the diagnosis and treatment of clinical POCD.

Effect of transverse thoracic muscle plane block on postoperative cognitive dysfunction after open cardiac surgery: A randomized clinical trial

The transversus thoracis muscle plane (TTMP) block provides effective analgesia in cardiac surgery patients. The aim of this study was to assess whether bilateral TTMP blocks can reduce the incidence of postoperative cognitive dysfunction (POCD) in patients undergoing cardiac valve replacement. A group of 103 patients were randomly divided into the TTM group (n = 52) and the PLA (placebo) group (n = 51). The primary endpoint was the incidence of POCD at 1 week after surgery. Secondary outcome measures included a reduction of intraoperative mean arterial pressure (MAP) >20% from baseline, intraoperative and postoperative sufentanil consumption, length of stay in the ICU, incidence of postoperative nausea and vomiting (PONV), time to first faeces, postoperative pain at 24 h after surgery, time to extubation and the length of hospital stay. Interleukin (IL)-6, TNF-α, S-100β, insulin, glucose and insulin resistance were measured at before induction of anaesthesia, 1, 3and 7 days after surgery. The MoCA scores were significantly lower and the incidence of POCD decreased significantly in TTM group compared with PLA group at 7 days after surgery. Perioperative sufentanil consumption, the incidence of PONV and intraoperative MAP reduction >20% from baseline, length of stay in the ICU, postoperative pain at 24 h after surgery, time to extubation and the length of hospital stay were significantly decreased in the TTM group. Postoperatively, IL-6, TNF-α, S-100β, HOMA-IR, insulin, glucose levels increased and the TTM group had a lower degree than the PLA group at 1, 3 and 7 days after surgery. In summary, bilateral TTMP blocks could improve postoperative cognitive function in patients undergoing cardiac valve replacement.

Abdominal surgery plus sevoflurane exposure induces abnormal emotional changes and cognitive dysfunction in aged rats

BACKGROUND

Cognitive impairment, which includes perioperative psychological distress and cognitive dysfunction, can be determined by preoperative and post-operative neuropsychological tests. Several mechanisms have been proposed regarding the two-way communication between the immune system and the brain after surgery. We aimed to understand the mechanisms underlying perioperative neurocognitive disorders (PND) in elderly rats using an experimental abdominal surgery model.

METHODS

24-month-old SD rats were exposed to the abdominal surgery model (AEL) under 3% anesthesia. On day 15 and day 30 post-surgery, fractional anisotropy (FA) using diffusion kurtosis imaging (DKI) was measured. From day 25 to day 30 post-surgery, behavioral tests, including open field test (OFT), Morris water maze (MWM), novel object recognition (NOR), force swimming test (FST), and elevated plus maze (EPM), were performed. Then, the rats were euthanized to perform pathological analysis and western blot measurement.

RESULTS

The rats exposed to AEL surgical treatment demonstrated significantly decreased time crossing the platform in the MWM, decreased recognition index in the NOR, reduced time in the open arm in the EPM, increased immobility time in the FST, and increased number of crossings in the OFT. Aged rats, after AEL exposure, further demonstrated decreased FA in the mPFC, nucleus accumbens (NAc), and hippocampus, together with reduced MAP2 intensity, attenuation of GAD65, VGlut2, CHAT, and phosphorylated P38MAPK expression, and increased reactive astrocytes and microglia.

CONCLUSIONS

In this study, the aged rats exposed to abdominal surgery demonstrated both emotional changes and cognitive dysfunction, which may be associated with neuronal degeneration and reduced phosphorylated P38MAPK.

Effects of sex and pro-inflammatory cytokines on context discrimination memory

In learning and memory tasks, immune overactivation is associated with impaired performance, while normal immune activation is associated with optimal performance. In one specific domain of memory, context discrimination memory, peripheral immune stimulation has been shown to impair performance on the context-object discrimination memory task in male rats. In order to evaluate potential sex differences in this task, as well as potential mechanisms for the memory impairment, we evaluated the ability of peripheral immune stimulation to impair task performance in both males and females. Next, we examined whether treatment with interleukin-1 receptor antagonist (IL-1ra), a receptor antagonist for the pro-inflammatory cytokine interleukin (IL)-1β, was able to rescue the memory deficit. We examined microglial morphology in the hippocampus and cytokine mRNA and protein expression in the hippocampus and the periphery. Male rats displayed memory impairment in response to LPS, and this impairment was not rescued by IL-1ra. Female rats did not have significant memory impairments and IL-1ra administration improved memory following inflammation. A subset of cytokines and chemokines were increased only in LPS-treated males. Inflammation alone did not alter microglia morphology, but IL-1ra did in certain sub-regions of the hippocampus. Together, these results indicate that sex differences exist in the ability of a peripheral immune stimulus to influence context discrimination memory and specific cytokine signals may be altered in impaired males. This study highlights the importance of sex differences in response to inflammatory challenges, especially related to memory impairments in context discrimination memory.

Involvement of KCa3.1 channel activity in immediate perioperative cognitive and neuroinflammatory outcomes

BACKGROUND

Potassium channels (KCa3.1; Kv1.3; Kir2.1) are necessary for microglial activation, a pivotal requirement for the development of Perioperative Neurocognitive Disorders (PNDs). We previously reported on the role of microglial Kv1.3 for PNDs; the present study sought to determine whether inhibiting KCa3.1 channel activity affects neuroinflammation and prevents development of PND.

METHODS

Mice (wild-type [WT] and KCa3.1^-/-) underwent aseptic tibial fracture trauma under isoflurane anesthesia or received anesthesia alone. WT mice received either TRAM34 (a specific KCa3.1 channel inhibitor) dissolved in its vehicle (miglyol) or miglyol alone. Spatial memory was assessed in the Y-maze paradigm 6 h post-surgery/anesthesia. Circulating interleukin-6 (IL-6) and high mobility group box-1 protein (HMGB1) were assessed by ELISA, and microglial activitation Iba-1 staining.

RESULTS

In WT mice surgery induced significant cognitive decline in the Y-maze test, p = 0.019), microgliosis (p = 0.001), and increases in plasma IL-6 (p = 0.002) and HMGB1 (p = 0.001) when compared to anesthesia alone. TRAM34 administration attenuated the surgery-induced changes in cognition, microglial activation, and HMGB1 but not circulating IL-6 levels. In KCa3.1^-/- mice surgery neither affected cognition nor microgliosis, although circulating IL-6 levels did increase (p < 0.001).

CONCLUSION

Similar to our earlier report with Kv1.3, perioperative microglial KCa3.1 blockade decreases immediate perioperative cognitive changes, microgliosis as well as the peripheral trauma marker HMGB1 although surgery-induced IL-6 elevation was unchanged. Future research should address whether a synergistic interaction exists between blockade of Kv1.3 and KCa3.1 for preventing PNDs.

Anti-inflammatory medication use associated with reduced delirium risk and all-cause mortality: A retrospective cohort study

OBJECTIVE

To investigate the relationship between history of anti-inflammatory medication use and delirium risk, as well as long-term mortality.

METHODS

In this retrospective cohort study, subjects recruited between January 2016 and March 2020 were analyzed. Information about anti-inflammatory medication use history including aspirin, NSAIDs, glucosamine, and other anti-inflammatory drugs, was collected. Logistic regression analysis investigated the relationship between anti-inflammatory medications and delirium. Log-rank analysis and cox proportional hazards model investigated the relationship between anti-inflammatory medications and one-year mortality.

RESULTS

The data from 1274 subjects were analyzed. The prevalence of delirium was significantly lower in subjects with NSAIDs usage (23.0%) than in those without NSAIDs usage (35.0%) (p < 0.001). Logistic regression analysis controlling for age, sex, dementia status, and hospitalization department showed that the risk of delirium tended to be reduced by a history of NSAIDs use (OR, 0.76 [95% CI, 0.55 to 1.03]). The one-year mortality in the subjects with NSAIDs (survival rate, 0.879 [95% CI, 0.845 to 0.906]) was significantly higher than in the subjects without NSAIDs (survival rate, 0.776 [95% CI, 0.746 to 0.803]) (p < 0.001). A history of NSAIDs use associated with the decreased risk of one-year mortality even after adjustment for age, sex, Charlson Comorbidity Index, delirium status, and hospitalization department (HR, 0.70 [95% CI, 0.51 to 0.96]).

CONCLUSION

This study suggested that NSAIDs usage was associated with decreased delirium prevalence and lower one-year mortality. The potential benefit of NSAIDs on delirium risk and mortality were shown.

Mannose-coated superparamagnetic iron oxide nanozyme for preventing postoperative cognitive dysfunction

Postoperative cognitive dysfunction (POCD) is associated with increased postoperative morbidity and mortality in patients. Excessive production of reactive oxygen species (ROS) and the consequent inflammatory response in the postoperative brain play crucial roles in the development of POCD. However, effective ways to prevent POCD have yet to be developed. Moreover, effective penetration of the blood-brain barrier (BBB) and maintaining viability in vivo are major challenges for preventing POCD using traditional ROS scavengers. Herein, mannose-coated superparamagnetic iron oxide nanoparticles (mSPIONs) were synthesized by co-precipitation method. The BBB penetration of mSPIONs was verified through fluorescent imaging and ICP-MS quantification. The ROS scavenging and anti-inflammatory of mSPIONs were evaluated in H₂O₂-treated J774A.1 ​cells and in tibial fracture mice model. The novel object recognition (NOR) and trace-fear conditioning (TFC) were used to test the cognitive function of postoperative mice. The average diameter of mSPIONs was approximately 11 ​nm. mSPIONs significantly reduced ROS levels in H₂O₂-treated cells and in hippocampus of surgical mice. mSPIONs administration reduced the levels of IL-1β and TNF-α in the hippocampus and inhibited surgery-upregulated HIF1-α/NF-κB signaling pathway. Moreover, mSPIONs significantly improved the cognitive function of postoperative mice. This study provides a new approach for preventing POCD using a nanozyme.

Prevention of Postoperative Cognitive Dysfunction by Minocycline in Elderly Patients after Total Knee Arthroplasty: A Randomized, Double-blind, Placebo-controlled Clinical Trial

BACKGROUND

There are no effective pharmacologic interventions for preventing postoperative cognitive dysfunction in daily practice. Since the antibiotic minocycline is known to suppress postoperative neuroinflammation, this study hypothesized and investigated whether minocycline might have a preventive effect on postoperative cognitive dysfunction after noncardiac surgery.

METHODS

This study included patients aged more than 60 yr undergoing total knee arthroplasty under general anesthesia. They were randomly assigned to minocycline and placebo groups, to orally receive 100 mg of minocycline or placebo twice daily from the day before surgery until the seventh day after surgery. Cognitive function was evaluated before surgery, and 1 week and 3 months after surgery, using a battery of four cognitive function tests, including Visual Verbal Learning Test, Trail Making Test, Stroop Color and Word Test, and Letter-Digit Coding Task. Additionally, 30 healthy volunteers were subjected to the same tests as the patients to examine the learning effect of repeated tests. The occurrence of postoperative cognitive dysfunction was judged from the results of the neurocognitive test battery, with consideration of the learning effect. The secondary endpoints were the effects of minocycline on postoperative delirium and postoperative pain.

RESULTS

A total of 100 patients were randomized to the minocycline group, and 102 were randomized to the placebo group. The average age of patients was 75 yr. Evaluation showed no significant difference in the incidence of postoperative cognitive dysfunction between the minocycline and placebo groups at both 1 week (8 of 90 [8.9%] vs. 4 of 95 [4.2%]; odds ratio, 2.22 [95% CI, 0.64 to 7.65]; P = 0.240) and 3 months (15.3 of 90 [17.0%] vs. 15.3 of 95 [16.1%]; odds ratio, 1.07 [95% CI, 0.49 to 2.32]; P = 0.889) postoperatively. Missing data 3 months after surgery were corrected by the multiple imputation method. There were no differences between the two groups in postoperative delirium and postoperative pain.

CONCLUSIONS

Minocycline is likely to have no preventive effect on postoperative cognitive dysfunction.

EDITOR’S PERSPECTIVE

Microfluidics-assisted blood-brain barrier device: a powerful tool to study perioperative neurocognitive disorder

The dysfunction of the blood-brain barrier could contribute to the pathogenesis of the perioperative neurocognitive disorder. In a recent study published in the British Journal of Anaesthesia, Yang and colleagues developed an innovative microfluidics-assisted blood-brain barrier device to investigate the effects of neuroimmune interactions on blood-brain barrier opening. The findings are important and timely to understanding the mechanistic insights of perioperative neurocognitive disorder.

Protective effects of omega-3 fatty acids in a blood-brain barrier-on-chip model and on postoperative delirium-like behaviour in mice

BACKGROUND

Peripheral surgical trauma can trigger neuroinflammation and ensuing neurological complications, such as delirium. The mechanisms whereby surgery contributes to postoperative neuroinflammation remain unclear and without effective therapies. Here, we developed a microfluidic-assisted blood-brain barrier (BBB) device and tested the effects of omega-3 fatty acids on neuroimmune interactions after orthopaedic surgery.

METHODS

A microfluidic-assisted BBB device was established using primary human cells. Tight junction proteins, vascular cell adhesion molecule 1 (VCAM-1), BBB permeability, and astrocytic networks were assessed after stimulation with interleukin (IL)-1β and in the presence or absence of a clinically available omega-3 fatty acid emulsion (Omegaven®; Fresenius Kabi, Bad Homburg, Germany). Mice were treated 1 h before orthopaedic surgery with 10 μl g-1 body weight of omega-3 fatty acid emulsion i.v. or equal volumes of saline. Changes in pericytes, perivascular macrophages, BBB opening, microglial activation, and inattention were evaluated.

RESULTS

Omega-3 fatty acids protected barrier permeability, endothelial tight junctions, and VCAM-1 after exposure to IL-1β in the BBB model. In vivo studies confirmed that omega-3 fatty acid treatment inhibited surgery-induced BBB impairment, microglial activation, and delirium-like behaviour. We identified a novel role for pericyte loss and perivascular macrophage activation in mice after surgery, which were rescued by prophylaxis with i.v. omega-3 fatty acids.

CONCLUSIONS

We present a new approach to study neuroimmune interactions relevant to perioperative recovery using a microphysiological BBB platform. Changes in barrier function, including dysregulation of pericytes and perivascular macrophages, provide new targets to reduce postoperative delirium.

Cognitive deficits after general anaesthesia in animal models: a scoping review

BACKGROUND

It remains controversial whether general anaesthetic drugs contribute to perioperative neurocognitive disorders in adult patients. Preclinical studies have generated conflicting results, likely because of differing animal models, study protocols, and measured outcomes. This scoping review of preclinical studies addressed the question: 'Do general anaesthetic drugs cause cognitive deficits in adult animals that persist after the drugs have been eliminated from the brain?'

METHODS

Reports of preclinical studies in the MEDLINE database published from 1953 to 2021 were examined. A structured review process was used to assess original studies of cognitive behaviours, which were measured after treatment (≥24 h) with commonly used general anaesthetic drugs in adult animals.

RESULTS

The initial search yielded 380 articles, of which 106 were fully analysed. The most frequently studied animal model was male (81%; n=86/106) rodents (n=106/106) between 2-3 months or 18-20 months of age. Volatile anaesthetic drugs were more frequently studied than injected drugs, and common outcomes were memory behaviours assessed using the Morris water maze and fear conditioning assays. Cognitive deficits were detected in 77% of studies (n=82/106) and were more frequent in studies of older animals (89%), after inhaled anaesthetics, and longer drug treatments. Limitations of the studies included a lack of physiological monitoring, mortality data, and risk of bias attributable to the absence of randomisation and blinding.

CONCLUSIONS

Most studies reported cognitive deficits after general anaesthesia, with age, use of volatile anaesthetic drugs, and duration of anaesthesia as risk factors. Recommendations to improve study design and guide future research are presented.