Jianbin Tong

Surgery Upregulates High Mobility Group Box‐1 and Disrupts the Blood–Brain Barrier causing Cognitive Dysfunction in Aged Rats

Postoperative cognitive dysfunction (POCD) is a growing and largely underestimated problem without defined etiology. Herein, we sought to determine the relationship between cognitive decline, blood–brain barrier (BBB) permeability, and inflammation, namely high mobility group box‐1 (HMGB1), after surgery in aged rats.

Systemic HMGB1 Neutralization Prevents Postoperative Neurocognitive Dysfunction in Aged Rats

Postoperative neurocognitive disorders are common complications in elderly patients following surgery or critical illness. High mobility group box 1 protein (HMGB1) is rapidly released after tissue trauma and critically involved in response to sterile injury. Herein, we assessed the role of HMGB1 after liver surgery in aged rats and explored the therapeutic potential of a neutralizing anti-HMGB1 monoclonal antibody in a clinically relevant model of postoperative neurocognitive disorders. Nineteen to twenty-two months Sprague-Dawley rats were randomly assigned as: (1) control with saline; (2) surgery, a partial hepatolobectomy under sevoflurane anesthesia and analgesia, + immunoglobulin G as control antibody; (3) surgery + anti-HMGB1. A separate cohort of animals was used to detect His-tagged HMGB1 in the brain. Systemic anti-HMGB1 antibody treatment exerted neuroprotective effects preventing postoperative memory deficits and anxiety in aged rats by preventing surgery-induced reduction of phosphorylated cyclic AMP response element-binding protein in the hippocampus. Although no evident changes in the intracellular distribution of HMGB1 in hippocampal cells were noted after surgery, HMGB1 levels were elevated on day 3 in rat plasma samples. Experiments with tagged HMGB1 further revealed a critical role of systemic HMGB1 to enable an access to the brain and causing microglial activation. Overall, these data demonstrate a pivotal role for systemic HMGB1 in mediating postoperative neuroinflammation. This may have direct implications for common postoperative complications like delirium and postoperative cognitive dysfunction.

Aging Differentially Affects the Loss of Neuronal Dendritic Spine, Neuroinflammation and Memory Impairment at Rats after Surgery

It is known that age is an important factor for postoperative cognitive dysfunction (POCD) and the patients with POCD suffer from the impairment of multiple brain regions and multiple brain functions. However currently animal studies of POCD mainly focus on hippocampus region, therefore in this study we performed partial hepatectomy in young adult and aged rats to test the questions (1) whether POCD in animals involves other brain areas besides hippocampus; (2) how age influences POCD of young adult and aged animals. We found that (1) in young adult rats, the memory was not significantly affected (P>0.05) 1d, 3d and 7d after partial hepatectomy, but was significantly impaired (p<0.001) in aged rats 1d and 3d post-surgery; (2) in young adult rats, the surgery did not significantly affect the densities of dendritic spines of neurons at CA1, dentate gyrus (DG) and cingulate cortex (P>0.05, respectively) 1d and 3d post-surgery, but the spine densities at CA1 and DG of aged rats were significant reduced 1d and 3d post-surgery (p<0.001, respectively), however this didn’t happen at cingulate cortex (P>0.05); (3) In young adult rats, surgery didn’t affect the activation of microglia and levels of TNF-α and IL-1β at hippocampus (P>0.05), but significantly activated microglia and increased levels of TNF-α and IL-1β at hippocampus of aged rats (P<0.05). Our data suggest that (1) partial hepatectomy-induced POCD mainly involves hippocampus impairments, and (2) differential loss of neuronal dendritic spines and neuroinflammation at hippocampus are most likely the mechanism for the formation of POCD in aged rats.

BACE1 in the retina: a sensitive biomarker for monitoring early pathological changes in Alzheimer's disease.

Because of a lack of sensitive biomarkers, the diagnosis of Alzheimer′s disease (AD) cannot be made prior to symptom manifestation. Therefore, it is crucial to identify novel biomarkers for the presymptomatic diagnosis of AD. While brain lesions are a major feature of AD, retinal pathological changes also occur in patients. In this study, we investigated the temporal changes in β-site APP-cleaving enzyme 1 (BACE1) expression in the retina and brain to determine whether it could serve as a suitable biomarker for early monitoring of AD. APP/PS-1 transgenic mice, 3, 6 and 8 months of age, were used as an experimental group, and age-matched C57/BL6 wild-type mice served as the control group. In the Morris water maze test, there were no significant differences in escape latency or in the number of crossings in the target area among mice of different ages. Compared with wild-type mice, no changes in learning or memory abilities were detected in transgenic mice at 3 months of age. However, compared with wild-type mice, the escape latency was significantly increased in transgenic mice at 6 months, starting on day 3, and at 8 months, starting on day 2, during Morris water maze training. In addition, the number of crossings of the target area was significantly decreased in transgenic mice. The learning and memory abilities of transgenic mice were further worsened at 8 months of age. Immunohistochemical staining revealed no BACE1 plaques in wild-type mice at 3, 6 or 8 months or in transgenic mice at 3 months, but they were clearly found in the entorhinal cortex, hippocampus and prefrontal cortex of transgenic mice at 6 and 8 months. BACE1 expression was not detected in the retina of wild-type mice at 3 months, but weak BACE1 expression was detected in the ganglion cell layer, inner plexiform layer and outer plexiform layer at 6 and 8 months. In transgenic mice, BACE1 expression in the ganglion cell layer was increased at 3 months, and BACE1 expression in the ganglion cell layer, inner plexiform layer and outer plexiform layer was significantly increased at 6 and 8 months, compared with age-matched wild-type mice. Taken together, these results indicate that changes in BACE1 expression appear earlier in the retina than in the brain and precede behavioral deficits. Our findings suggest that abnormal expression of BACE1 in the retina is an early pathological change in APP/PS-1 transgenic mice, and that BACE1 might have potential as a biomarker for the early diagnosis of AD in humans.

Preoperative Cognitive Intervention Reduces Cognitive Dysfunction in Elderly Patients after Gastrointestinal Surgery: A Randomized Controlled Trial

Background Preoperative conditions may play a significant role in postoperative cognitive dysfunction (POCD) development in elderly patients. We aimed to investigate whether preoperative cognitive training could lower the incidence of POCD one week after surgery. Material/Methods A total of 141 ASA I–III elderly patients who underwent gastrointestinal surgery were enrolled into the study. Patients were randomized into either the Intervention group (69 analyzed) or the Control group (72 analyzed). Patients in the intervention group were instructed and trained in a cognition mnemonic skill for a total of three 1-hour sessions with the method of loci (MoL). Controls did not receive any cognitive training during hospitalization. All patients were tested using neuropsychological battery tests (NPTs) on admission and one week after surgery. Result The incidence of POCD in the intervention group (15.9%) was significantly lower than in the controls (36.1%) (P<0.05). Patients’ performance in Brief Visuospatial Memory Test-Revised and Symbol-Digit Modalities Test were improved by the cognitive training. Increasing age, longer length of anesthesia and surgery, and lack of cognitive training were associated with a significantly higher risk of POCD (P<0.05). Conclusions Cognitive training with MoL can reduce the decline of early postoperative cognitive function in elderly patients undergoing major gastrointestinal surgery.

comt Gene Haplotypes Are Closely Associated with Postoperative Fentanyl Dose in Patients

BACKGROUND:Fentanyl’s analgesic efficacy varies widely among individuals. The single-nucleotide polymorphisms (SNPs) of catechol-O-methyltransferase (COMT) modulate sensitivity to pain. It remains unclear, however, whether COMT genetic variability affects postoperative fentanyl analgesia in patients undergoing radical gastrectomy. METHODS:One hundred fifteen patients, ASA physical status I–III, who were scheduled for radical gastrectomy under general anesthesia, were enrolled in this study. Patient-controlled IV analgesia with fentanyl was administered during the first 48 hours after surgery. Visual analog scale score for patients’ pain was maintained at ⩽30 mm. The amount of fentanyl consumed and side effects were recorded for the first 24 and 48 hours postoperatively. The SNPs of COMT (rs6269, rs4633, rs4818, and rs4680) of all patients were screened by DNA sequence analysis of polymerase chain reaction−amplified DNA or polymerase chain reaction-restriction fragment length polymorphism. RESULTS:There were no significant differences in the doses of fentanyl used among patients possessing different SNPs of COMT rs6269, rs4633, rs4818, and rs4680 at 24 (all P > 0.207) and 48 (all P > 0.148) hours after surgery. COMT gene haplotypes combined by COMT rs6269, rs4633, rs4818, and rs4680, however, significantly affected fentanyl consumption at 24 (P = 0.029) and 48 (P = 0.032) hours after surgery. Among the haplotypes of COMT gene, patients with haplotype ACCG consumed more fentanyl than GCGG and ATCA haplotypes during the first 24 and 48 hours (all P < 0.042) after surgery. No significant differences were found in the incidence of nausea, vomiting, and dizziness among the 4 SNPs of COMT gene (all P > 0.079) and their haplotypes (all P > 0.482). CONCLUSIONS:COMT gene haplotype constructed by rs6269, rs4633, rs4818, and rs4680 contributes to the individual variation of postoperative analgesia with fentanyl. Patients carrying the COMT gene haplotype ACCG consumed the most drug during the first 24 and 48 hours postoperatively.

Propranolol Attenuates Surgical Stress–Induced Elevation of the Regulatory T Cell Response in Patients Undergoing Radical Mastectomy

Surgical stress and inflammatory response induce the release of catecholamines and PGs, which may be key factors in facilitating cancer recurrence through immunosuppression. Animal studies have suggested the efficacy of perioperative blockades of catecholamines and PGs in reducing immunosuppression. In this study, to our knowledge, we present the first report of the effects of perioperative propranolol and/or parecoxib on peripheral regulatory T cells (Tregs) in breast cancer patients. Patients were randomly assigned to control, propranolol, parecoxib, and propranolol plus parecoxib groups. We demonstrated that levels of circulating epinephrine, norepinephrine, and PGE2 increased in response to surgery. Meanwhile, peripheral FOXP3 mRNA level and Treg frequencies were elevated on postoperative day 7. Propranolol administration, rather than parecoxib, attenuated such elevation of Tregs, indicating the critical roles for catecholamines in surgery-induced promotion of Tregs. Besides, propranolol plus parecoxib treatment demonstrated no additive or synergistic effects. Furthermore, a study of Treg activity on CD4+ T cell responses to specific tumor Ags was performed in the control and propranolol groups. Propranolol abrogated the increased Treg activity and accompanying suppression of CD4+ T cell responses after surgery. Finally, we conducted ex vivo experiments on the effects of varying concentrations of epinephrine and/or propranolol on Treg proliferation over PBMCs from breast cancer patients, to provide further direct evidence strengthening our clinical observations. Epinephrine markedly promoted Treg proliferation, whereas propranolol prevented such enhancement effect. In conclusion, our study highlights beneficial roles for propranolol in inhibiting Treg responses in vivo and in vitro, and demonstrates that propranolol could alleviate surgical stress–induced elevation of Tregs in breast cancer patients.

Aspartic acid in the hippocampus: a biomarker for postoperative cognitive dysfunction

This study established an aged rat model of cognitive dysfunction using anesthesia with 2% isoflurane and 80% oxygen for 2 hours. Twenty-four hours later, Y-maze test results showed that isoflurane significantly impaired cognitive function in aged rats. Gas chromatography-mass spectrometry results showed that isoflurane also significantly increased the levels of N,N-diethylacetamide, n-ethylacetamide, aspartic acid, malic acid and arabinonic acid in the hippocampus of isoflurane-treated rats. Moreover, aspartic acid, N,N-diethylacetamide, n-ethylacetamide and malic acid concentration was positively correlated with the degree of cognitive dysfunction in the isoflurane-treated rats. It is evident that hippocampal metabolite changes are involved in the formation of cognitive dysfunction after isoflurane anesthesia. To further verify these results, this study cultured hippocampal neurons in vitro, which were then treated with aspartic acid (100 μmol/L). Results suggested that aspartic acid concentration in the hippocampus may be a biomarker for predicting the occurrence and disease progress of cognitive dysfunction.

Dexmedetomidine Inhibits Maturation and Function of Human Cord Blood-Derived Dendritic Cells by Interfering with Synthesis and Secretion of IL-12 and IL-23.

Aims To investigate the effects and underlying mechanism of dexmedetomidine on the cultured human dendritic cells (DCs). Methods Human DCs and cytotoxic T lymphocytes (CTLs) were obtained from human cord blood mononuclear cells by density gradient centrifugation. Cultured DCs were divided into three groups: dexmedetomidine group, dexmedetomidine plus yohimbine (dexmedetomidine inhibitor) group and control group. DCs in the three groups were treated with dexmedetomidine, dexmedetomidine plus yohimbine and culture medium, respectively. After washing, the DCs were co-incubated with cultured CTLs. The maturation degree of DCs was evaluated by detecting (1) the ratios of HLA-DR-, CD86-, and CD80-positive cells (flow cytometry), and (2) expression of IL-12 and IL-23 (PCR and Elisa). The function of DCs was evaluated by detecting the proliferation (MTS assay) and cytotoxicity activity (the Elisa of IFN-γ) of CTLs. In addition, in order to explore the mechanisms of dexmedetomidine modulating DCs, α2-adrenergic receptor and its downstream signals in DCs were also detected. Results The ratios of HLA-DR-, CD86-, and CD80-positive cells to total cells were similar among the three groups (P>0.05). Compared to the control group, the protein levels of IL-12 and IL-23 in the culture medium and the mRNA levels of IL-12 p35, IL-12 p40 and IL-23 p19 in the DCs all decreased in dexmedetomidine group (P<0.05). In addition, the proliferation of CTLs and the secretion of IFN-γ also decreased in the dexmedetomidine group, compared with the control group (P<0.05). Moreover, these changes induced by dexmedetomidine in the dexmedetomidine group were reversed by α2-adrenergic receptor inhibitor yohimbine in the dexmedetomidine plus yohimbine group. It was also found the decrease of mRNA levels of IL-12 p35, IL-12 p40 and IL-23 p19 in the dexmedetomidine group could be reversed by ERK1/2 or AKT inhibitors. Conclusion Dexmedetomidine could negatively modulate human immunity by inhibiting the maturation of DCs and then decreasing the proliferation and cytotoxicity activity of CTLs. The α2-adrenergic receptors and its downstream molecules ERK1/2 and AKT are closely involved in the modulation of dexmedetomidine on DCs.

Age of Rats Seriously Affects the Degree of Retinal Damage Induced by Acute High Intraocular Pressure

Abstract Purpose: To investigate whether retinal impairment was affected by age of rats in acute glaucoma model. Methods: Young adult and aged rats were randomly divided into normal control, 45 mmHg, 60 mmHg and 90 mmHg groups. Intraocular pressures (IOP) of rats were acutely elevated to 45 mmHg, 60 mmHg and 90 mmHg, respectively. Neuron loss in ganglion cell layer (GCL) and activation of retinal macrolgia and microglia 3 days after high IOP treatment were detected by immunofluorescence and further quantitatively analyzed. Results: Compared with normal control, significant loss of neurons at GCL of young adult retina wasn’t detected until IOP treatment of 90 mmHg. In contrast, obvious loss of neurons at GCL of aged retina was detected at IOP of 45 mmHg (p = 0.002 for central; p = 0.001 for peripheral). The loss level of neurons of aged retina was significantly higher than that of young adult retina at different IOP treatments. Compared with the young adult retina, high IOP induced more significant increase at area percentage of microglia and microglia number in inner part of aged retina. Activation of microglia and macroglia was either in parallel to or earlier than neuron loss of GCL of aged and young adult retina. Conclusion: Our data suggest there exists an age–related susceptibility of rat retina to the increased IOP. Therefore, the effect of ages should be considered at glaucoma study of rat models.