Transmission of Alzheimer's disease-associated microbiota dysbiosis and its impact on cognitive function: evidence from mice and patients.

Spouses of Alzheimer's disease (AD) patients are at a higher risk of developing incidental dementia. However, the causes and underlying mechanism of this clinical observation remain largely unknown. One possible explanation is linked to microbiota dysbiosis, a condition that has been associated with AD. However, it remains unclear whether gut microbiota dysbiosis can be transmitted from AD individuals to non-AD individuals and contribute to the development of AD pathogenesis and cognitive impairment. We, therefore, set out to perform both animal studies and clinical investigation by co-housing wild-type mice and AD transgenic mice, analyzing microbiota via 16S rRNA gene sequencing, measuring short-chain fatty acid amounts, and employing behavioral test, mass spectrometry, site-mutations and other methods. The present study revealed that co-housing between wild-type mice and AD transgenic mice or administrating feces of AD transgenic mice to wild-type mice resulted in AD-associated gut microbiota dysbiosis, Tau phosphorylation, and cognitive impairment in the wild-type mice. Gavage with Lactobacillus and Bifidobacterium restored these changes in the wild-type mice. The oral and gut microbiota of AD patient partners resembled that of AD patients but differed from healthy controls, indicating the transmission of microbiota. The underlying mechanism of these findings includes that the butyric acid-mediated acetylation of GSK3ß at lysine 15 regulated its phosphorylation at serine 9, consequently impacting Tau phosphorylation. Pending confirmative studies, these results provide insight into a potential link between the transmission of AD-associated microbiota dysbiosis and development of cognitive impairment, which underscore the need for further research in this area.

Genetic liability to multi-site chronic pain increases the risk of cardiovascular disease.

BACKGROUND: Observational studies have shown associations between multi-site chronic pain (MCP) and cardiovascular disease. However, it remains unclear whether these associations are causal. Therefore, this study aimed to assess the causal associations between MCP and cardiovascular disease and identify possible mediators between them. METHODS: A two-sample Mendelian randomisation analysis was applied in this study. The summary data for MCP were obtained from a genome-wide association study that included 387 649 individuals from the UK Biobank, whereas summary-level data for cardiovascular disease and its subtypes were obtained from relevant genome-wide association studies. Finally, summary-level data for common cardiovascular risk factors and inflammatory biomarkers were leveraged to identify possible mediators. RESULTS: Genetic liability to multi-site chronic pain is associated with higher risks for coronary artery disease (CAD), myocardial infarction (MI), heart failure (HF), and stroke, with a combined odds ratio (OR) of 1.537 (per site increment in MCP; 95% confidence interval [CI]: 1.271-1.858; P=0.0001) for CAD, 1.604 (95% CI: 1.277-2.014; P=0.0005) for MI, 1.722 (95% CI: 1.423-2.083; P<0.00001) for HF, and 1.332 (95% CI: 1.093-1.623; P=0.00001) for stroke. Genetic liability to MCP was found to be associated with mental disorders, smoking initiation, physical activity, BMI, and lipid metabolites. Multivariable Mendelian randomisation suggested a mediating role for mental disorders, smoking initiation, physical activity, and BMI in the relationship between multi-site chronic pain and cardiovascular disease. CONCLUSIONS: Our findings provide new insights into the role of multi-site chronic pain in cardiovascular disease. Additionally, we identified several modifiable risk factors for reducing cardiovascular disease.

Transmission of Alzheimer's Disease-Associated Microbiota Dysbiosis and its Impact on Cognitive Function: Evidence from Mouse Models and Human Patients.

Spouses of Alzheimer's disease (AD) patients are at higher risk of developing AD dementia, but the reasons and underlying mechanism are unknown. One potential factor is gut microbiota dysbiosis, which has been associated with AD. However, it remains unclear whether the gut microbiota dysbiosis can be transmitted to non-AD individuals and contribute to the development of AD pathogenesis and cognitive impairment. The present study found that co-housing wild-type mice with AD transgenic mice or giving them AD transgenic mice feces caused AD-associated gut microbiota dysbiosis, Tau phosphorylation, and cognitive impairment. Gavage with Lactobacillus and Bifidobacterium restored these changes. The oral and gut microbiota of AD patient partners resembled that of AD patients but differed from healthy controls, indicating the transmission of oral and gut microbiota and its impact on cognitive function. The underlying mechanism of these findings includes that the butyric acid-mediated acetylation of GSK3ß at lysine 15 regulated its phosphorylation at serine 9, consequently impacting Tau phosphorylation. These results provide insight into a potential link between gut microbiota dysbiosis and AD and underscore the need for further research in this area.

Risk factors associated with postoperative complications following free flap reconstruction of head and neck defects.

BACKGROUND: Free flap reconstruction of head and neck defects is routinely performed with a high success rate nowadays. However, postoperative complications are still commonly observed. The aim of this study is to investigate risk factors correlated with postoperative complications following free flap reconstruction of head and neck defects. METHODS: A retrospective study of all patients undergoing free flap reconstruction of head and neck defects between January 2018 and January 2020 at Sun Yat-sen Memorial Hospita, Guangzhou, China was performed. Preoperative, intraoperative, and postoperative data were collected retrospectively. The primary outcome variables were postoperative complications, which were divided into medical and surgical complications. All patients were grouped by either complications or no complications. Univariate and multivariate logistic regression models were used to identify risk factors predicting complications. RESULTS: 850 patients underwent free flap reconstruction of head and neck defects during the study period (Male: 65.29%; Mean [SD] age: 54.90 [13.78] years). Postoperative complications developed in 125 (14.71%) patients, among which, 101 (11.88%) patients developed surgical complications, 29 (3.41%) patients developed medical complications and 5 (0.59%) patients developed both surgical and medical complications. Total flap necrosis was observed in 11 (1.29%) patients. After multivariate analysis, several risk factors incluing postoperative ICU admission, coronary heart disease, post radiotherapy surgery and flap types were identified correlated with postoperative complications. CONCLUSIONS: Our study identified related variables for a higher risk of postoperative complications development following free flap reconstruction of head and neck defects. Early detection of these risk factors will improve prognosis.

MG53 Protects against Sepsis-Induced Myocardial Dysfunction by Upregulating Peroxisome Proliferator-Activated Receptor-α.

BACKGROUND: The heart is one of the most commonly affected organs during sepsis. Mitsugumin-53 (MG53) has attracted attention in research due to its cardioprotective function. However, the role of MG53 in sepsis-induced myocardial dysfunction (SIMD) remains unknown. The purpose of this study was to explore the underlying mechanism of MG53 in SIMD and investigate its potential relationship with peroxisome proliferator-activated receptor-α (PPARα). METHODS: The cecal ligation and puncture (CLP) model was created to induce SIMD in rats. Protein levels of MG53 and PPARα, cardiac function, cardiomyocyte injury, myocardial oxidative stress and inflammatory indicators, and cardiomyocyte apoptosis were measured at 18 h after CLP. The effects of MG53 on PPARα in SIMD were investigated via preconditioning recombinant human MG53 (rhMG53) and PPARα antagonist GW6471. RESULTS: The expression of MG53 and PPARα sharply decreased in the myocardium at 18 h after CLP. Compared with the sham group, cardiac function was significantly depressed, which was associated with the destructed myocardium, upregulated oxidative stress indicators and proinflammatory cytokines, and excessive cardiomyocyte apoptosis in the CLP group. Supplementation with rhMG53 enhanced myocardial MG53, increased the survival rate with improved cardiac function, and reduced oxidative stress, inflammation, and myocardial apoptosis, which were associated with PPARα upregulation. Pretreatment with GW6471 abolished the abovementioned protective effects induced by MG53. CONCLUSIONS: Both MG53 and PPARα were downregulated after sepsis shock. MG53 supplement protects the heart against SIMD by upregulating PPARα expression. Our results provide a new treatment strategy for SIMD.

Anesthesia and surgery induce age-dependent changes in behaviors and microbiota.

The neuropathogenesis of postoperative delirium remains mostly unknown. The gut microbiota is implicated in the pathogenesis of neurological disorders. We, therefore, set out to determine whether anesthesia/surgery causes age-dependent gut microbiota dysbiosis, changes in brain IL-6 level and mitochondrial function, leading to postoperative delirium-like behavior in mice. Female 9 or 18 months old mice received abdominal surgery under 1.4% isoflurane for two hours. The postoperative delirium-like behavior, gut microbiota, levels of brain IL-6, PSD-95 and synaptophysin, and mitochondrial function were determined by a battery of behavioral tests, 16s rRNA sequencing, ELISA, Western blot and Seahorse XFp Extracellular Flux Analyzer. Intragastric administration of Lactobacillus (10 days) and probiotic (20 days) were used to mitigate the anesthesia/surgery-induced changes. Anesthesia/surgery caused different alterations in gut microbiota, including change rate of reduction in the levels of gut lactobacillus, between the 18 and 9 months old mice. The anesthesia/surgery induced greater postoperative delirium-like behavior, increased brain IL-6 levels, decreased PSD-95 and synaptophysin levels, and mitochondrial dysfunction in 18 than 9 months old mice. Treatments with Lactobacillus and probiotic mitigated the anesthesia/surgery-induced changes. These data suggest that microbiota dysbiosis may contribute to neuropathogenesis of postoperative delirium and treatment with Lactobacillus or a probiotic could mitigate postoperative delirium.

Development and validation of a nomogram incorporating selected systemic inflammation-based prognostic marker for complication prediction after vascularized fibula flap reconstruction.

OBJECTIVE: To develop and validate a nomogram incorporating systemic inflammatory markers (the Albumin/NLR Score [ANS]) to predict postoperative complications after vascularized fibula flap reconstruction. PATIENTS AND METHODS: A total of 238 patients who underwent vascularized fibula flap reconstruction between March 2012 and December 2016 were collected as the primary cohort. Univariable and multivariable analysis were performed to identify independent risk factors for postoperative complications. Backward stepwise logistic regression analysis was then applied with and without the ANS; and nomograms were established based on these criteria. Independent validation of these nomograms was carried out in an independent validation cohort including 106 consecutive patients from December 2016 and January 2018. RESULTS: Radiotherapy history (odds ratio [OR] = 0.336; 95% CI, 0.157-0.717; P = 0.005), the ANS (OR = 0.248; 95% CI, 0.093-0.661; P = 0.005) and fluid infusion rate over 24 h (OR = 0.671; 95% CI, 0.479-0.94; P = 0.02) were identified as independent risk factors for postoperative complications. A higher C-index was found in both the primary (0.759; 95% CI, 0.719-0.739) and validation cohort (0.704; 95% CI, 0.613-0.659) for the nomogram incorporating the ANS, and NRI was 0.496 (95% CI, 0.072-0.920; P = 0.022) comparing of these nomograms. Furthermore, a wider threshold probability (0.2-0.9) and superior clinical value were observed in the nomogram incorporating the ANS on the decision curve. CONCLUSION: The ANS was an independent risk factor for postoperative complications associated with vascularized fibula flap reconstruction. The nomogram incorporating the ANS was established with better accuracy and showed more potential clinical benefit for the estimation of postoperative complications.

Acute Fasting Does Not Induce Cognitive Impairment in Mice.

Preoperative baseline cognitive impairment is associated with postoperative neurocognitive disorder (PND). Fasting, and more generally, calorie restriction has been shown to exert controversial effects in clinical settings and various animal models of neurological disorders. Every patient needs acute fasting before anesthesia and surgery. However, the impact of acute fasting on cognitive function remain largely unknown. We, therefore, set out to determine whether acute fasting can induce neurotoxicity and neurobehavioral deficits in rodents. In the present system establishment study, a mouse model of acute fasting was established. The effects of the acute fasting on natural and learned behavior were evaluated in the buried food test, open field test and the Y maze test. The expression of c-Fos, the marker of neuronal activation, and caspase-3 activation, the marker of cellular apoptosis, were measured with immunohistochemistry. We found that the 9 h acute fasting increased the latency to eat food in the buried food test. The acute fasting also selectively increased the total distance and decreased the freezing time in open field test, and increased the duration in the novel arm in the Y maze test. Besides, the immunohistochemical study showed that the fasting significantly increased the c-Fos level in the hippocampus and various sub-cortical areas, including paraventricular thalamus (PVT), dorsomedial hypothalamus (DMH), lateral hypothalamus (LH), and basal amygdala (BMA). However, the acute fasting did not induce apoptosis, demonstrating by no appearance of caspase-3 activation in the corresponding brain areas. These data showed that acute fasting did not cause cellular apoptosis and cognitive impairment in the mice. Instead, the acute fasting increased the neuronal activity, enhanced the ambulatory activity and improved the spatial recognition memory in the mice. These findings will promote more research in the established system to further determine the effects of perioperative factors on the postoperative neurocognitive function and the underlying mechanisms.

Cyclophilin D Contributes to Anesthesia Neurotoxicity in the Developing Brain.

Anesthetic sevoflurane induces mitochondrial dysfunction, impairment of neurogenesis, and cognitive impairment in young mice, but the underlying mechanism remains to be determined. Cyclophilin D (CypD) is a modulatory factor for the mitochondrial permeability transition pore (mPTP). We, therefore, set out to evaluate the role of CypD in these sevoflurane-induced changes in vitro and in young mice. Wild-type (WT) and CypD knockout (KO) young (postnatal day 6, 7, and 8) mice received 3% sevoflurane 2 h daily and the neural progenitor cells (NPCs) harvested from the WT or CypD KO mice received 4.1% sevoflurane. We used immunohistochemistry and immunocytochemistry imaging, flow cytometry, Western blot, RT-PCR, co-immunoprecipitation, and Morris Water Maze to assess the interaction of sevoflurane and CypD on mitochondria function, neurogenesis, and cognition in vitro and in WT or CypD KO mice. We demonstrated that the sevoflurane anesthesia induced accumulation of CypD, mitochondrial dysfunction, impairment of neurogenesis, and cognitive impairment in WT mice or NPCs harvested from WT mice, but not in CypD KO mice or NPCs harvested from CypD KO mice. Furthermore, the sevoflurane anesthesia reduced the binding of CypD with Adenine nucleotide translocator, the other component of mPTP. These data suggest that the sevoflurane anesthesia might induce a CypD-dependent mitochondria dysfunction, impairment of neurogenesis, and cognitive impairment in young mice and NPCs.

Sevoflurane Acts on Ubiquitination-Proteasome Pathway to Reduce Postsynaptic Density 95 Protein Levels in Young Mice.

BACKGROUND: Children with multiple exposures to anesthesia and surgery may have an increased risk of developing cognitive impairment. Sevoflurane, a commonly used anesthetic in children, has been reported to decrease levels of postsynaptic density 95 protein. However, the upstream mechanisms and downstream consequences of the sevoflurane-induced reduction in postsynaptic density 95 protein levels remains largely unknown. We therefore set out to assess whether sevoflurane acts on ubiquitination-proteasome pathway to facilitate postsynaptic density 95 protein degradation. METHODS: Six-day-old wild-type mice received anesthesia with 3% sevoflurane 2 h daily for 3 days starting on postnatal day 6. We determined the effects of the sevoflurane anesthesia on mRNA, protein and ubiquitinated levels of postsynaptic density 95 protein in neurons, and synaptosomes and hippocampus of young mice. Cognitive function in the mice was determined at postnatal day 31 by using a Morris water maze. Proteasome inhibitor MG132 and E3 ligase mouse double mutant 2 homolog inhibitor Nutlin-3 were used for the interaction studies. RESULTS: The sevoflurane anesthesia decreased protein, but not mRNA, levels of postsynaptic density 95, and reduced ubiquitinated postsynaptic density 95 protein levels in neurons, synaptosomes, and hippocampus of young mice. Both MG132 and Nutlin-3 blocked these sevoflurane-induced effects. Sevoflurane promoted the interaction of mouse double mutant 2 homolog and postsynaptic density 95 protein in neurons. Finally, MG132 and Nutlin-3 ameliorated the sevoflurane-induced cognitive impairment in the mice. CONCLUSIONS: These data suggest that sevoflurane acts on the ubiquitination-proteasome pathway to facilitate postsynaptic density 95 protein degradation, which then decreases postsynaptic density 95 protein levels, leading to cognitive impairment in young mice. These studies would further promote the mechanistic investigation of anesthesia neurotoxicity in the developing brain.