Consistent patterns in the inconsistent associations of Insulin-like growth factor 1 (IGF-1), C-Reactive Protein (C-RP) and Interleukin 6 (IL-6) levels with delirium in surgical populations. A systematic review and meta-analysis

Exploring the Pathophysiology of Delirium: An Overview of Biomarker Studies, Animal Models, and Tissue-Engineered Models

Delirium is an acute brain disorder associated with disorganized thinking, difficulty focusing, and confusion that commonly follows major surgery, severe infection, and illness. Older patients are at high risk for developing delirium during hospitalization, which may contribute to increased morbidity, longer hospitalization, and increased risk of institutionalization following discharge. The pathophysiology underlying delirium remains poorly studied. This review delves into the findings from biomarker studies and animal models, and highlights the potential for tissue-engineered models of the brain in studying this condition. The aim is to bring together the existing knowledge in the field and provide insight into the future direction of delirium research.

Inflammatory and nutritional markers predict the risk of post-operative delirium in elderly patients following total hip arthroplasty

Objectives

This study intended to explore whether albumin-associated inflammatory and nutritional markers could predict post-operative delirium (POD) in older patients after total hip arthroplasty (THA). In addition, we established a nomogram model for POD prediction.

Methods

Totally, 254 elderly cases who received THA were included. Clinical and laboratory data of these patients were retrospectively collected. Albumin-associated inflammatory and nutritional markers included neutrophil-to-albumin ratio (NAR), CRP-to-albumin ratio (CAR), prognostic nutritional index (PNI), and systemic inflammation score (SIS). The LASSO, univariate and multivariate logistic regression analyses were utilized to screen risk factors. A nomogram model was developed according to the results of multivariate regression analyses.

Results

Among 254 patients, 49 cases had POD with an incidence of 19.3%. LASSO regression and multivariate logistic analyses suggested that preoperative NAR, preoperative PNI, preoperative SIS, and age >75 years were risk factors for POD. A nomogram model was developed according to the results of multivariate logistic analyses. The calibration curve suggested that the predicted probability of this nomogram model was in good line with the actual probability. The DCA showed that this nomogram model had net benefits for the prediction of POD for elderly patients following THA.

Conclusion

Albumin-associated inflammatory and nutritional markers including NAR, PNI, and SIS could predict POD in elderly patients following THA.

Role of hypoxia-inducible factor in postoperative delirium of aged patients: A review

Postoperative delirium is common, especially in older patients. Delirium is associated with prolonged hospitalization, an increased risk of postoperative complications, and significant mortality. The mechanism of postoperative delirium is not yet clear. Cerebral desaturation occurred during the maintenance period of general anesthesia and was one of the independent risk factors for postoperative delirium, especially in the elderly. Hypoxia stimulates the expression of hypoxia-inducible factor-1 (HIF-1), which controls the hypoxic response. HIF-1 may have a protective role in regulating neuron apoptosis in neonatal hypoxia-ischemia brain damage and may promote the repair and rebuilding process in the brain that was damaged by hypoxia and ischemia. HIF-1 has a neuroprotective effect during cerebral hypoxia and controls the hypoxic response by regulating multiple pathways, such as glucose metabolism, angiogenesis, erythropoiesis, and cell survival. On the other hand, anesthetics have been reported to inhibit HIF activity in older patients. So, we speculate that HIF plays an important role in the pathophysiology of postoperative delirium in the elderly. The activity of HIF is reduced by anesthetics, leading to the inhibition of brain protection in a hypoxic state. This review summarizes the possible mechanism of HIF participating in postoperative delirium in elderly patients and provides ideas for finding targets to prevent or treat postoperative delirium in elderly patients.

Biomarkers of delirium risk in older adults: a systematic review and meta-analysis

Delirium is a neuropsychiatric syndrome associated with increased morbidity and mortality in older patients. The aim of this study was to review predictive biomarkers of delirium in older patients to gain insights into the pathophysiology of this syndrome and provide guidance for future studies. Two authors independently and systematically searched MEDLINE, Embase, Cochrane Library, Web of Science and Scopus databases up to August 2021. A total of 32 studies were included. Only 6 studies were eligible for the meta-analysis, pooled results showed a significant increase in some serum biomarkers (C-reactive protein [CRP], tumour necrosis factor alpha [TNF-α] and interleukin-6 [IL-6]) among patients with delirium (odds ratio = 1.88, 95% CI 1.01 to 1.637; I2 = 76.75%). Although current evidence does not favour the use of any particular biomarker, serum CRP, TNF-α, and IL-6 were the most consistent biomarkers of delirium in older patients.

Preclinical and translational models for delirium: Recommendations for future research from the NIDUS delirium network

Delirium is a common, morbid, and costly syndrome that is closely linked to Alzheimer's disease (AD) and AD-related dementias (ADRD) as a risk factor and outcome. Human studies of delirium have advanced our knowledge of delirium incidence and prevalence, risk factors, biomarkers, outcomes, prevention, and management. However, understanding of delirium neurobiology remains limited. Preclinical and translational models for delirium, while challenging to develop, could advance our knowledge of delirium neurobiology and inform the development of new prevention and treatment approaches. We discuss the use of preclinical and translational animal models in delirium, focusing on (1) a review of current animal models, (2) challenges and strategies for replicating elements of human delirium in animals, and (3) the utility of biofluid, neurophysiology, and neuroimaging translational markers in animals. We conclude with recommendations for the development and validation of preclinical and translational models for delirium, with the goal of advancing awareness in this important field.

Evaluation of 18F-FAPI-04 Imaging in Assessing the Therapeutic Response of Rheumatoid Arthritis

PURPOSE

Fibroblast activating protein (FAP) is highly expressed in the synovial tissues of rheumatoid arthritis (RA) patients. The aim of this study was to determine the feasibility of PET imaging with an Al[¹⁸F] F-NOTA-labeled FAP inhibitor 04(¹⁸F-FAPI-04) for the evaluation of arthritic progression and therapeutic response in experimental arthritis.

METHODS

Fibroblast-like synoviocytes (FLSs) were obtained from patients with RA or osteoarthritis (OA), and the relationship between ¹⁸F-FAPI-04 uptake and the inflammatory activity of RA FLSs was investigated. Collagen-induce arthritis (CIA) mice models were established and treated with methotrexate (MTX) or etanercept (ETC). Then, PET imaging was performed 24 h following ¹⁸F-FAPI-04 injection. The imaging results were compared by assessing macroscopic arthritis scores and histological staining.

RESULTS

¹⁸F-FAPI-04 uptake was obvious in RA FLSs that characterizing FAP activation. The higher the uptake of ¹⁸F-FAPI-04, the more severity of the inflammatory phenotype in RA FLS. Furthermore, the uptake of ¹⁸F-FAPI-04 in inflamed joints could be found even before the deformity of the parental joints could be observed by histological examination. Both MTX and ETC were effective in inhibiting the progression of arthritis in CIA mice was confirmed by macroscopic, histological, and radiographic pathology scores. Importantly, ¹⁸F-FAPI-04 uptake declined accordingly in CIA models following MTX and ETC treatment.

CONCLUSIONS

These findings suggest that PET imaging of ¹⁸F-FAPI-04 can be used to monitor treatment response in RA, and is more sensitive in disease speculation than macroscopic arthritis scoring.

The effect of parecoxib sodium on postoperative delirium in elderly patients with hip arthroplasty

Objective: This study aimed to clarify the effect of parecoxib sodium on the occurrence of postoperative delirium and to investigate its possible mechanism. Methods: A total of 80 patients who underwent elective hip arthroplasty in our hospital between December 2020 and December 2021 were selected and randomly divided into two groups: a parecoxib sodium group (group P, n = 40) and a control group (group C, n = 40). Patients in group P were intravenously injected with 40 mg of parecoxib sodium 30 min before anesthesia and at the end of the surgery. Patients in group C were intravenously injected with the same volume of normal saline at the same time points. The primary endpoint was the incidence of POD, and the secondary endpoints were the levels of inflammatory factors (tumor necrosis factor- α [TNF-α], interleukin [IL]-1β, IL-6, and IL-10), nerve injury-related factors (brain-derived neurotrophic factor [BDNF], S-100β protein, neuron-specific enolase [NSE], and neurofilament light chain [NfL]), and antioxidant factors (heme oxygenase-1 [HO-1]), as well as the Visual Analogue Scale (VAS) and Confusion Assessment Method-Chinese Reversion (CAM-CR) scores. Results: The incidence of POD was 10% in group P and 27.5% in group C. Intergroup comparison revealed that the levels of TNF-α, IL-1β, S-100β, NfL, and NSE were lower, and BDNF was higher, in group P than in group C at each postoperative time point. The levels of IL-6 were lower, and the levels of IL-10 and HO-1 were higher, in group P than in group C at 1 h and 1 day postoperatively (p < 0.05). Three days after surgery, the differences in the levels of IL-6, IL-10, and HO-1 were not statistically significant between the two groups (p > 0.05). The VAS and CAM-CR scores were lower at each postoperative time point in group P than in group C (p < 0.05). Conclusion: Parecoxib sodium could reduce postoperative pain, decrease the plasma levels of inflammatory and nerve injury-related factors, upregulate HO-1 levels, and reduce the incidence of POD. The results of this study suggest that parecoxib sodium may reduce the occurrence of POD through the effects of anti-inflammation, analgesia, and antioxidants.

Longitudinal Profiling of Plasma Cytokines and Its Association With Postoperative Delirium in Elderly Patients Undergoing Major Lower Limb Surgery: A Prospective Observational Study

BACKGROUND

Surgery is accompanied by a systemic inflammatory response that may presage delirium in susceptible individuals. Little is known about the trajectory of plasma proinflammatory cytokines and their potential associations with postoperative delirium (POD). The current study longitudinally assessed both pro and anti-inflammatory plasma cytokine response and development of POD in older surgical patients to investigate associations with individual and/or clusters of cytokines that may indicate pathogenic mechanisms.

METHODS

A prospective longitudinal study sought to enroll patients >60 years old who were scheduled for major lower limb surgery under general anesthesia. Blood was obtained preoperatively and postoperatively from day 1 through postoperative day 4 for measurement of plasma interleukin-1β (IL-1β), IL-2, IL-4, IL-6, soluble IL-6 receptor (sIL-6R), IL-10, and tumor necrosis factor-α (TNF-α). Participants were assessed for POD twice daily for 4 days using the confusion assessment method. Trajectory of postoperative changes in plasma cytokines was determined by a group-based trajectory modeling analysis that was informed by distinct cytokines identified by time-dependent Cox regression model.

RESULTS

One hundred eighty-eight patients were assessed for eligibility of whom 129 underwent major surgery and 126 had complete datasets for final analysis. POD was diagnosed in 31 of 126 patients (24.6%). Time-dependent Cox regression model identified that higher IL-6 and sIL-6R levels were associated with higher risk of developing POD. A two-cluster model (stable lower and fluctuating higher levels) was considered to be the most statistically appropriate model for IL-6 and sIL-6R trajectory. More participants with fluctuating higher IL-6 were delirious (73.3% vs 18.0%, P = .001) as were those with fluctuating higher sIL-6R (81.3% vs 16.4%, P = .001).

CONCLUSIONS

As higher IL-6 and sIL-6R levels were significantly associated with higher risk of POD and the combination is required for IL-6 trans-signaling, it is possible that activation of this pathway may be associated with POD. Furthermore, it will be important to determine whether high levels of the combination of IL-6 and sIL-6R can be an early biomarker for the subsequent development of POD.

Detection Analysis of Perioperative Plasma and CSF Reveals Risk Biomarkers of Postoperative Delirium of Parkinson's Disease Patients Undergoing Deep Brain Stimulation of the Subthalamic Nuclei

Objective

This study aimed to explore possible biomarkers of postoperative delirium (POD) of Parkinson's disease (PD) patients received deep brain stimulation (DBS) of the subthalamic nuclei.

Materials and methods

This nested case control study analyzed perioperative plasma and cerebral spinal fluid (CSF) of patients (n = 40) who developed POD undergone DBS surgery (n = 10) and those who did not (n = 30). Blood sample was collected before surgery and on the first day postoperative, CSF sample was collected at the beginning of the operation. POD was assessed by the Confusion Assessment Method (CAM) twice a day between 7:00 am and 7:00 pm after the surgery until discharge. Plasma and CSF sample from the two groups were analyzed to investigate possible biomarkers for POD in PD patients.

Results

There was no difference between POD and Non-POD groups on the concentration of Interleukin 6 and Tumor Necrosis Factor-α in CSF, preoperative plasma and postoperative plasma. There was no difference between POD and Non-POD groups on the concentration of S100 calcium-binding protein β protein (S100β) and Neurofilament light chain (NFL) in preoperative plasma and postoperative plasma. The concentration of C-reactive protein (CRP), NFL and S100β were significant higher in POD group than non-POD group in CSF. The concentration of CRP was significantly higher in POD group than non-POD group in preoperative plasma and postoperative plasma. CSF concentration of S100β might be a potential biomarker for POD via the receiver operating characteristic curve analysis and the area under the curve value of 0.973.

Conclusion

For PD patients received DBS surgery, CSF S100β might be a marker for aiding detection of high-risk patients with delirium. This requires further confirmation in clinical trials.

Correlation Analysis of Inflammatory Markers CRP and IL-6 and Postoperative Delirium (POD) in Elderly Patients: A Meta-Analysis of Observational Studies

Background

Postoperative delirium (POD) is very common in the elderly surgical population, and its occurrence is associated with multiple factors such as preoperative, intraoperative, and postoperative factors, and the increase of serum inflammatory markers such as C-reactive protein (CRP) and interleukin-6 (IL-6) is considered to be associated with the occurrence of POD, but the results of multiple studies are inconsistent. In this study, we investigated the correlation between inflammatory markers CRP and IL-6 and POD in elderly patients by literature search and meta-analysis.

Methods

We searched PubMed, Web of Science, the Cochrane library, Embase, Ovid, and Springer Link for cohort studies or case-control studies that investigated the factors involved in the occurrence of POD, used the Newcastle-Ottawa Scale (NOS) to assess the quality of the selected literature, and combined the differences in serum CRP and IL-6 levels between POD and non-POD patients after surgery to evaluate the predictive value of CRP and IL-6 for the occurrence of POD.

Results

This research comprised 16 papers for quantitative analysis, with a total of 2967 patients, 758 with POD and 2209 with non-POD. There were 16 cohort studies (100%) and 0 case-control studies (0%) across all the collected literatures; there were 15 prospective cohort studies and 1 retrospective cohort research. A meta-analysis revealed a statistically significant difference in serum IL-6 levels between POD patients after surgery and non-POD patients [MD = 115.68, 95% CI (25.70, 206.66), Z = 2.52, P = 0.012], as well as a statistically significant difference in serum CRP levels [MD = 27.67, 95% CI (12.77, 42.58), Z = 3.64, P = 0.0003]. Discussion. Early after surgery, serum IL-6 and CRP levels were considerably higher in POD patients than in non-POD patients, indicating that early serum inflammatory variables are likely to be predictors of POD. After surgery, the levels of the aforementioned inflammatory factors should be actively monitored to forecast the emergence of delirium, and active treatment should be used to limit the creation and release of the aforementioned inflammatory factors.

Midazolam impacts acetyl-And butyrylcholinesterase genes: An epigenetic explanation for postoperative delirium?

Midazolam is a widely used short-acting benzodiazepine. However, midazolam is also criticized for its deliriogenic potential. Since delirium is associated with a malfunction of the neurotransmitter acetylcholine, midazolam appears to interfere with its proper metabolism, which can be triggered by epigenetic modifications. Consequently, we tested the hypothesis that midazolam indeed changes the expression and activity of cholinergic genes by acetylcholinesterase assay and qPCR. Furthermore, we investigated the occurrence of changes in the epigenetic landscape by methylation specific PCR, ChiP-Assay and histone ELISA. In an in-vitro model containing SH-SY5Y neuroblastoma cells, U343 glioblastoma cells, and human peripheral blood mononuclear cells, we found that midazolam altered the activity of acetylcholinesterase /buturylcholinesterase (AChE / BChE). Interestingly, the increased expression of the buturylcholinesterase evoked by midazolam was accompanied by a reduced methylation of the BCHE gene and the di-methylation of histone 3 lysine 4 and came along with an increased expression of the lysine specific demethylase KDM1A. Last, inflammatory cytokines were not induced by midazolam. In conclusion, we found a promising mechanistic link between midazolam treatment and delirium, due to a significant disruption in cholinesterase homeostasis. In addition, midazolam seems to provoke profound changes in the epigenetic landscape. Therefore, our results can contribute to a better understanding of the hitherto poorly understood interactions and risk factors of midazolam on delirium.