The Non-peptide Angiotensin-(1-7) Mimic AVE 0991 Attenuates Delayed Neurocognitive Recovery After Laparotomy by Reducing Neuroinflammation and Restoring Blood-Brain Barrier Integrity in Aged Rats

TIMP-3 Alleviates White Matter Injury After Subarachnoid Hemorrhage in Mice by Promoting Oligodendrocyte Precursor Cell Maturation

Subarachnoid hemorrhage (SAH) is associated with high mortality and disability rates, and secondary white matter injury is an important cause of poor prognosis. However, whether brain capillary pericytes can directly affect the differentiation and maturation of oligodendrocyte precursor cells (OPCs) and subsequently affect white matter injury repair has still been revealed. This study was designed to investigate the effect of tissue inhibitor of metalloproteinase-3 (TIMP-3) for OPC differentiation and maturation. PDGFRβret/ret and wild-type C57B6J male mice were used to construct a mouse model of SAH via endovascular perforation in this study. Mice were also treated with vehicle, TIMP-3 RNAi or TIMP-3 RNAi + TIMP-3 after SAH. The effect of TIMP-3 on the differentiation and maturation of OPCs was determined using behavioral score, ELISA, transmission electron microscopy, immunofluorescence staining and cell culture. We found that TIMP-3 was secreted mainly by pericytes and that SAH and TIMP-3 RNAi caused a significant decrease in the TIMP-3 content, reaching a nadir at 24 h, followed by gradual recovery. In vitro, the myelin basic protein content of oligodendrocytes after oxyhemoglobin treatment was increased by TIMP-3 overexpression. The data indicates TIMP-3 could promote the differentiation and maturation of OPCs and subsequently improve neurological outcomes after SAH. Therefore, TIMP-3 could be beneficial for repair after white matter injury and could be a potential therapeutic target in SAH.

Preoperative prognostic nutritional index value as a predictive factor for postoperative delirium in older adult patients with hip fractures: a secondary analysis

BACKGROUND

Malnutrition is a common geriatric syndrome and can be targeted preoperatively to decrease the risk of postoperative delirium (POD) in older adult patients. To analyze the value of the prognostic nutritional index (PNI) to predict the incidence of POD in older adult patients with hip fractures.

METHODS

This was a prospective, observational, cohort study of older adult patients with hip fractures. Preoperative PNI was calculated as 10 × serum albumin (g/dL) + 0.005 × total lymphocyte count (/μL) using preoperative laboratory results. Patients were divided into POD and non-POD groups using the Confusion Assessment Method (CAM). The risk factors associated with POD as well as the relationship between PNI values and the incidence of POD were analyzed using univariate and multivariate logistic regression analyses. The predictive value of PNI for POD was assessed using receiver operating characteristic curve analysis.

RESULTS

In this cohort of 369 patients who underwent hip fracture surgery, 67 patients (18.2%) were diagnosed with POD by the CAM results. Low PNI increased the risk of POD (odds ratio (OR) = 0.928, 95% confidence interval (CI): 0.864-0.997). General anesthesia (OR = 2.307, 95% CI: 1.279-4.162) and Mini-Mental State Examination (MMSE) score (OR = 0.956, 95% CI: 0.920-0.994) were also identified as risk factors for POD. Receiver operating characteristic curve analysis suggested that PNI combined with the anesthetic method and MMSE score may be used as a potential predictive indicator of POD after hip fracture surgery.

CONCLUSION

Preoperative PNI value is related to POD in older adult patients with hip fractures.

TRIAL REGISTRATION

This secondary analysis study was approved by the Peking University Third Hospital Medical Science Research Ethics Committee (approval No. M2022578) and registered in the Chinese Clinical Trial Registry (ChiCTR2300070569).

Advancement in Beneficial Effects of AVE 0991: A Brief Review

AVE 0991, a non-peptide analogue of Angiotensin-(1-7) [Ang-(1-7)], is orally active and physiologically well tolerated. Several studies have demonstrated that AVE 0991 improves glucose and lipid metabolism, and contains anti-inflammatory, anti-apoptotic, anti-fibrosis, and anti-oxidant effects. Numerous preclinical studies have also reported that AVE 0991 appears to have beneficial effects on a variety of systemic diseases, including cardiovascular, liver, kidney, cancer, diabetes, and nervous system diseases. This study searched multiple literature databases, including PubMed, Web of Science, EMBASE, Google Scholar, Cochrane Library, and the ClinicalTrials.gov website from the establishment to October 2022, using AVE 0991 as a keyword. This literature search revealed that AVE 0991 could play different roles via various signaling pathways. However, the potential mechanisms of these effects need further elucidation. This review summarizes the benefits of AVE 0991 in several medical problems, including the COVID-19 pandemic. The paper also describes the underlying mechanisms of AVE 0991, giving in-depth insights and perspectives on the pharmaceutical value of AVE 0991 in drug discovery and development.

Reciprocal interaction between mitochondrial fission and mitophagy in postoperative delayed neurocognitive recovery in aged rats

INTRODUCTION

Emerging evidence suggests that mitochondrial dysfunction plays a crucial role in the pathogenesis of postoperative delayed neurocognitive recovery (dNCR). Mitochondria exist in a dynamic equilibrium that involves fission and fusion to regulate morphology and maintains normal cell function via the removal of damaged mitochondria through mitophagy. Nonetheless, the relationship between mitochondrial morphology and mitophagy, and how they influence mitochondrial function in the development of postoperative dNCR, remains poorly understood. Here, we observed morphological alterations of mitochondria and mitophagy activity in hippocampal neurons and assessed the involvement of their interaction in dNCR following general anesthesia and surgical stress in aged rats.

METHODS

Firstly, we evaluated the spatial learning and memory ability of the aged rats after anesthesia/surgery. Hippocampal mitochondrial function and mitochondrial morphology were detected. Afterwards, mitochondrial fission was inhibited by Mdivi-1 and siDrp1 in vivo and in vitro separately. We then detected mitophagy and mitochondrial function. Finally, we used rapamycin to activate mitophagy and observed mitochondrial morphology and mitochondrial function.

RESULTS

Surgery impaired hippocampal-dependent spatial learning and memory ability and caused mitochondrial dysfunction. It also increased mitochondrial fission and inhibited mitophagy in hippocampal neurons. Mdivi-1 improved mitophagy and learning and memory ability of aged rats by inhibiting mitochondrial fission. Knocking down Drp1 by siDrp1 also improved mitophagy and mitochondrial function. Meanwhile, rapamycin inhibited excessive mitochondrial fission and improved mitochondrial function.

CONCLUSION

Surgery simultaneously increases mitochondrial fission and inhibits mitophagy activity. Mechanistically, mitochondrial fission/fusion and mitophagy activity interact reciprocally with each other and are both involved in postoperative dNCR. These mitochondrial events after surgical stress may provide novel targets and modalities for therapeutic intervention in postoperative dNCR.

Specific antagonist of receptor for advanced glycation end‑products attenuates delirium‑like behaviours induced by sevoflurane anaesthesia with surgery in aged mice partially by improving damage to the blood‑brain barrier

Postoperative delirium (POD), which occurs in hospital up to 1-week post-procedure or until discharge, is a common complication, especially in older adult patients. However, the pathogenesis of POD remains unclear. Although damage to blood-brain barrier (BBB) integrity is involved in the neuropathogenesis of POD, the specific role of the BBB in POD requires further elucidation. Anaesthesia using 2% isoflurane for 4 h results in the upregulation of hippocampal receptor for advanced glycation end-products (RAGE) expression and β-amyloid accumulation in aged rats. The present study investigated the role of RAGE in BBB integrity and its mechanisms in POD-like behaviours. The buried food, open field and Y maze tests were used to evaluate neurobehavioural changes in aged mice following 2.5% sevoflurane anaesthesia administration with exploratory laparotomy. Levels of tight junction proteins were assessed by western blotting. Multiphoton in vivo microscopy was used to observe the ultrastructural changes in the BBB in the hippocampal CA1 region. Anaesthesia with surgery decreased the levels of tight junction proteins occludin and claudin 5, increased matrix metalloproteinases (MMPs) 2 and 9, damaged the ultrastructure of the BBB and induced POD-like behaviour. FPS-ZM1, a specific RAGE antagonist, ameliorated POD-like behaviour induced by anaesthesia and surgery in aged mice. Furthermore, FPS-ZM1 also restored decreased levels of occludin and claudin 5 as well as increased levels of MMP2 and MMP9. The present findings suggested that RAGE signalling was involved in BBB damage following anaesthesia with surgery. Thus, RAGE has potential as a novel therapeutic intervention for the prevention of POD.

Angiotensin-(1-7) ameliorates intestinal barrier dysfunction by activating the Keap1/Nrf2/HO-1 signaling pathway in acute pancreatitis

BACKGROUND

Intestinal barrier dysfunction is a serious complication associated with acute pancreatitis (AP). Angiotensin (Ang)-(1-7) plays a protective role in the intestinal barrier, but the underlying mechanism remains clear. This study investigated the impact of Ang-(1-7) on AP-induced intestinal dysfunction and its involvement in the Keap1/Nrf2/HO-1 pathway.

METHODS AND RESULTS

We studied caerulein- and lipopolysaccharide (LPS)-induced AP in mice and an epithelial cell line (IEC-6) from the small intestinal crypt of rats. Ang-(1-7) was administered orally or via the tail vein. IEC-6 cells were divided into five groups: control; LPS; LPS + Ang-(1-7); LPS + Ang-(1-7) + ML385 (an Nrf2 inhibitor); and LPS + ML385. Pancreatic and intestinal histopathology scores were analyzed using the Schmidt and Chiu scores. The expression of intestinal barrier-associated proteins and Keap1/Nrf2/HO-1 pathway constituents was assessed by RT-PCR and western blotting. The peroxide and antioxidant activities in the IEC-6 cells were measured. Compared to those in AP mice, Ang-(1-7) diminished the intestinal levels of proinflammatory factors (interleukin-1β and tumor necrosis factor α) and serum levels of intestine permeability (D-lactate). Ang-(1-7) increased the expression of barrier-associated proteins (aquaporin-1, claudin-1, and occludin) compared to those in the AP and LPS group. Moreover, Ang-(1-7) promoted the Keap/Nrf2/HO-1 pathway, which resulted in significantly reduced malondialdehyde and increased superoxide dismutase levels.. However, ML385 abolished the effects of Ang-(1-7) on barrier-associated proteins and reversed the Keap1/Nrf2/HO-1 pathway.

CONCLUSIONS

Ang-(1-7) reduces AP-induced intestinal inflammation and oxidative injuries by activating the Keap1/Nrf2/HO-1 pathway.

Rapamycin Affects the Hippocampal SNARE Complex to Alleviate Cognitive Dysfunction Induced by Surgery in Aged Rats

Delayed neurocognitive recovery (dNCR) is a common complication that occurs post-surgery, especially in elderly individuals. The soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) complex plays an essential role in various membrane fusion events, such as synaptic vesicle exocytosis and autophagosome-lysosome fusion. Although SNARE complex dysfunction has been observed in several neurodegenerative disorders, the causal link between SNARE-mediated membrane fusion and dNCR remains unclear. We previously demonstrated that surgical stimuli caused cognitive impairment in aged rats by inducing α-synuclein accumulation, inhibiting autophagy, and disrupting neurotransmitter release in hippocampal synaptosomes. Here, we evaluated the effects of propofol anesthesia plus surgery on learning and memory and investigated levels of SNARE proteins and chaperones in hippocampal synaptosomes. Aged rats that received propofol anesthesia and surgery exhibited learning and memory impairments in a Morris water maze test and decreased levels of synaptosome-associated protein 25, synaptobrevin/vesicle-associated membrane protein 2, and syntaxin 1. Levels of SNARE chaperones, including mammalian uncoordinated-18, complexins 1 and 2, cysteine string protein-α, and N-ethylmaleimide-sensitive factor, were all significantly decreased following anesthesia with surgical stress. However, the synaptic vesicle marker synaptophysin was unaffected. The autophagy-enhancer rapamycin attenuated structural and functional disturbances of the SNARE complex and ameliorated disrupted neurotransmitter release. Our results indicate that perturbations of SNARE proteins in hippocampal synaptosomes may underlie the occurrence of dNCR. Moreover, the protective effect of rapamycin may partially occur through recovery of SNARE structural and functional abnormalities. Our findings provide insight into the molecular mechanisms underlying dNCR.

Teriparatide induces angiogenesis in ischemic cerebral infarction zones of rats through AC/PKA signaling and reduces ischemia-reperfusion injury

Teriparatide is a commonly used drug indicated for the treatment of osteoporosis in postmenopausal women. Teriparatide can also upregulate Ang-1 expression through the AC/PKA signaling pathway to promote angiogenesis. At present, promoting angiogenesis is a promising but unrealized strategy for the treatment of ischemic cerebral infarction. However, there are few studies on the application of teriparatide in the treatment of cerebral infarction. We used teriparatide to treat ischemic cerebral infarction in rats and obtained three major findings. First, teriparatide can promote angiogenesis, reduce cerebral infarct size, and increase cerebral perfusion by upregulating Ang-1 expression. Second, teriparatide can promote the expression of HO1, SOD2 and inhibit the production of pro-inflammatory cytokines IL-1β, IL-6 by upregulating Nrf2 expression. Third, we further found that teriparatide can mitigate blood-brain barrier disruption and brain edema by downregulating the expressions of MMP9, Ang-2 and AQP4. Our results indicate that teriparatide is neuroprotective through multiple mechanisms of action that include promoting angiogenesis, inhibiting oxidative stress and neuroinflammation, protecting blood-brain barrier, and reducing brain edema.

Angiotensin-(1-7) as a Potential Therapeutic Strategy for Delayed Cerebral Ischemia in Subarachnoid Hemorrhage

Aneurysmal subarachnoid hemorrhage (SAH) is a substantial cause of mortality and morbidity worldwide. Moreover, survivors after the initial bleeding are often subject to secondary brain injuries and delayed cerebral ischemia, further increasing the risk of a poor outcome. In recent years, the renin-angiotensin system (RAS) has been proposed as a target pathway for therapeutic interventions after brain injury. The RAS is a complex system of biochemical reactions critical for several systemic functions, namely, inflammation, vascular tone, endothelial activation, water balance, fibrosis, and apoptosis. The RAS system is classically divided into a pro-inflammatory axis, mediated by angiotensin (Ang)-II and its specific receptor AT₁R, and a counterbalancing system, presented in humans as Ang-(1-7) and its receptor, MasR. Experimental data suggest that upregulation of the Ang-(1-7)/MasR axis might be neuroprotective in numerous pathological conditions, namely, ischemic stroke, cognitive disorders, Parkinson's disease, and depression. In the presence of SAH, Ang-(1-7)/MasR neuroprotective and modulating properties could help reduce brain damage by acting on neuroinflammation, and through direct vascular and anti-thrombotic effects. Here we review the role of RAS in brain ischemia, with specific focus on SAH and the therapeutic potential of Ang-(1-7).

Renin-Angiotensin System Alterations in the Human Alzheimer's Disease Brain

BACKGROUND

Understanding Alzheimer's disease (AD) in terms of its various pathophysiological pathways is essential to unravel the complex nature of the disease process and identify potential therapeutic targets. The renin-angiotensin system (RAS) has been implicated in several brain diseases, including traumatic brain injury, ischemic stroke, and AD.

OBJECTIVE

This study was designed to evaluate the protein expression levels of RAS components in postmortem cortical and hippocampal brain samples obtained from AD versus non-AD individuals.

METHODS

We analyzed RAS components in the cortex and hippocampus of postmortem human brain samples by western blotting and immunohistochemical techniques in comparison with age-matched non-demented controls.

RESULTS

The expression of AT1R increased in the hippocampus, whereas AT2R expression remained almost unchanged in the cortical and hippocampal regions of AD compared to non-AD brains. The Mas receptor was downregulated in the hippocampus. We also detected slight reductions in ACE-1 protein levels in both the cortex and hippocampus of AD brains, with minor elevations in ACE-2 in the cortex. We did not find remarkable differences in the protein levels of angiotensinogen and Ang II in either the cortex or hippocampus of AD brains, whereas we observed a considerable increase in the expression of brain-derived neurotrophic factor in the hippocampus.

CONCLUSION

The current findings support the significant contribution of RAS components in AD pathogenesis, further suggesting that strategies focusing on the AT1R and AT2R pathways may lead to novel therapies for the management of AD.

Potential Serum Biomarkers for Postoperative Neurocognitive Disorders Based on Proteomic Analysis of Cognitive-Related Brain Regions

Postoperative neurocognitive disorders (po-NCD), including postoperative delirium (POD) and delayed neurocognitive recovery (dNCR), are common in geriatric surgical patients. However, the ideal diagnostic biomarkers to predict individual risks of po-NCDs have not been identified. In this study, proteomic analysis was used to detect dysregulated proteins in three cognitive-related brain regions, the hippocampus, prefrontal cortex, and temporal lobe, of aged dNCR rats. The common affected proteins in these three brain regions were further verified by real-time polymerase chain reaction and western blotting. Furthermore, serum samples from aged rats with dNCR and elderly hip fracture patients with POD were also assessed with enzyme linked immunosorbent assays to investigate the biomarker potential of these dysregulated proteins. The increased expression levels of haptoglobin, caseinolytic protease (ClpP), and alpha-2 macroglobulin (A2M) as well as decreased expression levels of 14-3-3β/α and biliverdin reductase-A (BVR-A) were validated by proteomic analysis in the hippocampus, prefrontal cortex, and temporal lobe of aged dNCR rats. The increased expression of haptoglobin and decreased expression of 14-3-3β/α were further demonstrated in the three brain regions by western blotting. Moreover, increased levels of S100A6 and BVR-A in the hippocampus, S100A6 in the prefrontal cortex, and A2M in the temporal lobe were also observed. More intriguingly, both decreased serum 14-3-3β/α and increased A2M in geriatric POD patients as well as decreased serum ClpP in aged dNCR rats were verified. These results not only indicate potential diagnostic biomarkers for po-NCD but also provide directions for further pathological investigations.

Clinical Trial Registration:www.ClinicalTrials.gov, identifier [ChiCTR1900027393].

Glibenclamide Attenuates Neuroinflammation and Promotes Neurological Recovery After Intracerebral Hemorrhage in Aged Rats

Intracerebral hemorrhage (ICH) is a common disease in the elderly population. Inflammation following ICH plays a detrimental role in secondary brain injury, which is associated with a poor prognosis of patients with ICH, and no efficient pharmacological preventions are available. Here, we investigated the effects of glibenclamide (GLC) on neuroinflammation in an autoblood-induced aged rat (18 months old) model of ICH. Rats were randomized into the sham, vehicle, and GLC groups. First, we investigated the expression level of sulfonylurea receptor 1 (Sur1) surrounding the hematoma after ICH. Then, neurological scores were calculated, and water maze tests, brain water content analysis, western blotting, and immunofluorescence assays were implemented to detect the neuroprotective effect of GLC. The expression of the Sur1-Trpm4 channel was significantly increased in the perihematomal tissue following ICH in aged rats. The GLC administration effectively reduced brain edema and improved neurofunction deficits following ICH. In addition, GLC increased the expression of brain-derived neurotrophic factors and decreased the expression of proinflammatory factors [tumor necrosis factor (TNF)-α,interleukin (IL)-1, and IL-6]. Moreover, GLC markedly reduced Ikappa-B (IκB) kinase (IKK) expression in microglia and nuclear factor (NF)-κB-P65 levels in perihematomal tissue. GLC ameliorated ICH-induced neuroinflammation and improved neurological outcomes in aged rats. In part, GLC may exert these effects by regulating the NF-κB signaling pathway through the Sur1-Trpm4 channel.

Cholecystokinin octapeptide improves hippocampal glutamatergic synaptogenesis and postoperative cognition by inhibiting induction of A1 reactive astrocytes in aged mice

Aims

Delayed neurocognitive recovery (dNCR) is a common postoperative complication in geriatric surgical patients for which there is no efficacious therapy. Cholecystokinin octapeptide (CCK‐8), an immunomodulatory peptide, regulates memory and learning. Here, we explored the effects and mechanism of action of CCK‐8 on dNCR.

Methods

We applied laparotomy to establish a model of dNCR in aged mice. Morris water maze and fear conditioning tests were used to evaluate cognition. Immunofluorescence was used to detect the density of CCK‐8, A1 reactive astrocytes, glutamatergic synapses, and activation of microglia in the hippocampus. Quantitative PCR was performed to determine mRNA levels of synapse‐associated factors. A1 reactive astrocytes, activated microglia, and glutamatergic synapse‐associated protein levels in the hippocampus were assessed by western blotting.

Results

Administration of CCK‐8 suppressed the activation of microglia, the induction of A1 reactive astrocytes, and the expression of tumor necrosis factor alpha, complement 1q, and interleukin 1 alpha in the hippocampus. Furthermore, it promoted glutamatergic synaptogenesis and neurocognitive recovery in aged dNCR model mice.

Conclusion

Our findings indicated that CCK‐8 alleviated cognitive impairment and promoted glutamatergic synaptogenesis by inhibiting the induction of A1 reactive astrocytes and the activation of microglia. CCK‐8 is, therefore, a potential therapeutic target for dNCR.