mtDNA-cGAS-STING axis-dependent NLRP3 inflammasome activation contributes to postoperative cognitive dysfunction induced by sevoflurane in mice.

The activation of NLRP3 inflammasome in microglia is critical for neuroinflammation during postoperative cognitive dysfunction (POCD) induced by sevoflurane. However, the molecular mechanism by which sevoflurane activates the NLRP3 inflammasome in microglia remains unclear. The cGAS-STING pathway is an evolutionarily conserved inflammatory defense mechanism. The role of the cGAS-STING pathway in sevoflurane-induced NLRP3 inflammasome-dependent neuroinflammation and the underlying mechanisms require further investigation. We found that prolonged anesthesia with sevoflurane induced cognitive dysfunction and triggered the neuroinflammation characterized by the activation of NLRP3 inflammasome in vivo. Interestingly, the cGAS-STING pathway was activated in the hippocampus of mice receiving sevoflurane. While the blockade of cGAS with RU.521 attenuated cognitive dysfunction and NLRP3 inflammasome activation in mice. In vitro, we found that sevoflurane treatment significantly activated the cGAS-STING pathway in microglia, while RU.521 pre-treatment robustly inhibited sevoflurane-induced NLRP3 inflammasome activation. Mechanistically, sevoflurane-induced mitochondrial fission in microglia and released mitochondrial DNA (mtDNA) into the cytoplasm, which could be abolished with Mdivi-1. Blocking the mtDNA release via the mPTP-VDAC channel inhibitor attenuated sevoflurane-induced mtDNA cytosolic escape and reduced cGAS-STING pathway activation in microglia, finally inhibiting the NLRP3 inflammasome activation. Therefore, regulating neuroinflammation by targeting the cGAS-STING pathway may provide a novel therapeutic target for POCD.

TREM-1 triggers necroptosis of macrophages through mTOR-dependent mitochondrial fission during acute lung injury.

BACKGROUND: Necroptosis of macrophages is a necessary element in reinforcing intrapulmonary inflammation during acute lung injury (ALI). However, the molecular mechanism that sparks macrophage necroptosis is still unclear. Triggering receptor expressed on myeloid cells-1 (TREM-1) is a pattern recognition receptor expressed broadly on monocytes/macrophages. The influence of TREM-1 on the destiny of macrophages in ALI requires further investigation. METHODS: TREM-1 decoy receptor LR12 was used to evaluate whether the TREM-1 activation induced necroptosis of macrophages in lipopolysaccharide (LPS)-induced ALI in mice. Then we used an agonist anti-TREM-1 Ab (Mab1187) to activate TREM-1 in vitro. Macrophages were treated with GSK872 (a RIPK3 inhibitor), Mdivi-1 (a DRP1 inhibitor), or Rapamycin (an mTOR inhibitor) to investigate whether TREM-1 could induce necroptosis in macrophages, and the mechanism of this process. RESULTS: We first observed that the blockade of TREM-1 attenuated alveolar macrophage (AlvMs) necroptosis in mice with LPS-induced ALI. In vitro, TREM-1 activation induced necroptosis of macrophages. mTOR has been previously linked to macrophage polarization and migration. We discovered that mTOR had a previously unrecognized function in modulating TREM-1-mediated mitochondrial fission, mitophagy, and necroptosis. Moreover, TREM-1 activation promoted DRP1Ser616 phosphorylation through mTOR signaling, which in turn caused surplus mitochondrial fission-mediated necroptosis of macrophages, consequently exacerbating ALI. CONCLUSION: In this study, we reported that TREM-1 acted as a necroptotic stimulus of AlvMs, fueling inflammation and aggravating ALI. We also provided compelling evidence suggesting that mTOR-dependent mitochondrial fission is the underpinning of TREM-1-triggered necroptosis and inflammation. Therefore, regulation of necroptosis by targeting TREM-1 may provide a new therapeutic target for ALI in the future.

Intermittent fasting attenuates lipopolysaccharide-induced acute lung injury in mice by modulating macrophage polarization.

Acute lung injury (ALI) is a spectrum of acute and life-threatening pulmonary inflammatory conditions. Treatment of ALI remains a clinical challenge. Recently, intermittent fasting (IF) has been shown to improve health and alleviate many diseases. In this study, we tested whether IF attenuated ALI and investigated the mechanism underlying this process. In vivo, the effects of IF on ALI were evaluated in a lipopolysaccharide (LPS)-induced murine ALI model. We found that two times of 24-h fasting in a week before ALI efficiently ameliorated LPS-induced lung injury in mice, characterized by alleviated lung lesions, wet-to-dry weight ratio, myeloperoxidase activity, malondialdehyde content, and lower levels of tumor necrosis factor-α, interleukin-6, and interleukin-1ß. In vitro, functional assays were conducted to assess IF on the inflammatory response and macrophage polarization of bone marrow-derived macrophages (BMDMs) treated with LPS or IL-4. And PPARγ antagonist GW9662 and AMPK siRNA were used to test the role of PPARγ and AMPK in the IF-mediated improvement of ALI. The results showed that IF (serum deprivation) suppressed macrophage M1 activation and promoted M2 activation in LPS-treated BMDMs. While, IF also augmented macrophage M2 polarization in IL-4-treated BMDMs. Further mechanistic studies showed that the promotive effect of IF on M2 polarization was related to the activation of the PPARγ and AMPK pathways. In conclusion, this study suggests that IF enhances M2 polarization by activating the AMPK and PPARγ pathways, thus facilitating anti-inflammatory response and ameliorating ALI.

Kindlin-2 Mediates Lipopolysaccharide-Induced Acute Lung Injury Partially via Pyroptosis in Mice.

Acute lung injury (ALI) is characteristic of the wholesale destruction of the lung endothelial barrier, which results in protein-rich lung edema, influx of pro-inflammatory leukocytes, and intractable hypoxemia, contributing to high mortality. Kindlin-2 is involved in the process of tumor- and wound healing-associated inflammation. However, the effects of kindlin-2 on lipopolysaccharide (LPS)-induced ALI and its mechanisms remain unknown. In this study, we found that the concentration of kindlin-2 was elevated in the lungs of ALI mice. The specific deletion of kindlin-2 by kindlin-2 siRNA attenuated the severity of lung injury, which was demonstrated by the reduced number of pro-inflammatory cells in bronchoalveolar lavage fluid and lung wet/dry weight ratio, and ameliorated pathologic changes in the lungs of ALI mice. Furthermore, kindlin-2 siRNA decreased the mRNA levels of pro-inflammatory factors (IL-1ß, IL-6, and TNF-α) and the protein levels of pyroptosis-related proteins. In vitro studies confirmed that LPS + ATP promoted the expressions of pro-inflammatory factors and pyroptosis-related proteins, which was prevented by kindlin-2 siRNA pretreatment in endothelial cells (ECs). In conclusion, inhibition of kindlin-2 developes protective effects against LPS-induced ALI and the cytotoxicity of ECs, which may depend on blocking pyroptosis.

Cerebral-Cardiac Syndrome and Diabetes: Cardiac Damage After Ischemic Stroke in Diabetic State.

Cerebral-cardiac syndrome (CCS) refers to cardiac dysfunction following varying brain injuries. Ischemic stroke is strongly evidenced to induce CCS characterizing as arrhythmia, myocardial damage, and heart failure. CCS is attributed to be the second leading cause of death in the post-stroke stage; however, the responsible mechanisms are obscure. Studies indicated the possible mechanisms including insular cortex injury, autonomic imbalance, catecholamine surge, immune response, and systemic inflammation. Of note, the characteristics of the stroke population reveal a common comorbidity with diabetes. The close and causative correlation of diabetes and stroke directs the involvement of diabetes in CCS. Nevertheless, the role of diabetes and its corresponding molecular mechanisms in CCS have not been clarified. Here we conclude the features of CCS and the potential role of diabetes in CCS. Diabetes drives establish a "primed" inflammatory microenvironment and further induces severe systemic inflammation after stroke. The boosted inflammation is suspected to provoke cardiac pathological changes and hence exacerbate CCS. Importantly, as the key element of inflammation, NOD-like receptor pyrin domain containing 3 (NLRP3) inflammasome is indicated to play an important role in diabetes, stroke, and the sequential CCS. Overall, we characterize the corresponding role of diabetes in CCS and speculate a link of NLRP3 inflammasome between them.

NLRP3 Inflammasome: A Potential Target in Isoflurane Pretreatment Alleviates Stroke-Induced Retinal Injury in Diabetes.

Ischemic stroke remains a devastating disease which is the leading cause of death worldwide. Visual impairment after stroke is a common complication which may lead to vision loss, greatly impacting life quality of patients. While ischemic stroke is traditionally characterized by a blockage of blood flow to the brain, this may coincide with reduced blood flow to the eye, resulting in retinal ischemia and leading to visual impairment. Diabetes increases the risk of ischemic stroke and induces diabetic retinopathy; the latter may be more sensitive to the ischemic retinal injury. In diabetic status, the underlying mechanism in stroke-induced retinal injury has not been fully clarified. The NLR pyrin domain containing 3 (NLRP3) inflammasome is an important activator of inflammation, which may play a critical role in catalyzing and forming certain pro-inflammatory cytokines in both cerebral and retinal ischemia. Isoflurane has been demonstrated to inhibit the activation of the NLRP3 inflammasome and show neuroprotective effects. In this study, we established a diabetic mouse model and performed the middle cerebral artery occlusion procedure to induce ischemic stroke. Our results revealed that cerebral ischemia-induced retinal injury in the diabetic model. Isoflurane pretreatment alleviated the cerebral and retinal injury after ischemic stroke. Of note, isoflurane pretreatment inhibited the NLRP3 inflammasome activation in the retina, indicating that isoflurane pretreatment may provide substantial retinal protection in stroke-induced retinal injury in diabetes.

Association of Olfactory Impairment and Postoperative Cognitive Dysfunction in Elderly Patients.

OBJECTIVE: To investigate the impact of anesthesia on the change of olfactory function and cognitive function in elderly patients who undergo abdominal surgery. METHODS: A total of 30 elderly patients who underwent abdominal surgery were recruited as the research subjects. The Connecticut Chemosensory Clinical Research Center (CCCRC) olfactory test was used to test the olfactory function and the Mini-mental State Examination (MMSE), Hopkins Verbal Learning Test - Revised (HVLT-R), Trail Making Test (TMT), Stroop Color Word Test (SCWT), Digit-Symbol Coding Test (DSCT), and Verbal Fluency Test (VFT) were used to assess their cognitive function before general anesthesia, and on the 3rd and 7th day post-anesthesia. The serum level of IL-1ß, IL-6, and TNF-α were measured before anesthesia and at 0, 12, and 24 h post-anesthesia. In total, 30 healthy volunteers who did not undergo anesthesia were used as the control group. The test results of all subjects were recorded and their correlations were analyzed. RESULTS: On the 3rd and 7th day post-anesthesia, the olfactory recognition threshold of patients in the surgical group was lower than that of control group with significant difference (P < 0.05). On the 3rd and 7th postoperative day, the patient's short-term memory and delayed memory, attention and processing speed were decreased (P < 0.05). On the 7th day post-anesthesia, delayed memory and processing ability were still decreased (P < 0.05). In the surgical group, Spearman correlation analysis showed that the difference of olfactory recognition score on the 3rd and 7th day post-anesthesia was positively correlated with short-term memory and delayed memory of cognitive function. Compared with pre-anesthesia, the serum levels of IL-1ß, IL-6, and TNF-α in the surgical group were significantly increased at each time point after anesthesia. CONCLUSION: Abdominal surgery with general anesthesia in elderly patients may increase the level of serum inflammatory factors, induce olfactory impairment, particularly the decline of olfactory identification threshold and cause cognitive dysfunction with declined short-term memory, delayed memory and attention. There was a positive correlation between olfactory impairment and cognitive dysfunction after general anesthesia. Therefore, olfactory impairment could be an early indicator to guide early intervention for postoperative cognitive dysfunction.

Update on neurological symptoms in patients infected with severe acute respiratory syndrome coronavirus-2.

Novel coronavirus 19 (COVID-19) is the latest and most intense epidemic, which is caused by the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). In addition to causing respiratory symptoms, SARS-CoV-2 can have severe effects on the nervous system. Clinically, COVID-19 patients have been reported ranging from mild hypogeusia and hyposmia to severe neurological disorders, such as encephalopathy, encephalitis, strokes, and seizures syndrome. However, the pathological mechanisms of this SARS-CoV-2 neuro aggressiveness remain unclear, so it is of great significance to explore the neurological effects of SARS-CoV-2 infection. To facilitate clinicians to timely recognize the manifestations of COVID-19 patients with neurological injury and timely treatment, the author hereby reviews the latest research progress in the possible pathways, clinical manifestations, and pathogenesis of COVID-19 patients with nerve injury.

Macrophage-NLRP3 Inflammasome Activation Exacerbates Cardiac Dysfunction after Ischemic Stroke in a Mouse Model of Diabetes.

Ischemic stroke is one of the leading causes of death worldwide. In the post-stroke stage, cardiac dysfunction is common and is known as the brain-heart interaction. Diabetes mellitus worsens the post-stroke outcome. Stroke-induced systemic inflammation is the major causative factor for the sequential complications, but the mechanism underlying the brain-heart interaction in diabetes has not been clarified. The NLRP3 (NLR pyrin domain-containing 3) inflammasome, an important component of the inflammation after stroke, is mainly activated in M1-polarized macrophages. In this study, we found that the cardiac dysfunction induced by ischemic stroke is more severe in a mouse model of type 2 diabetes. Meanwhile, M1-polarized macrophage infiltration and NLRP3 inflammasome activation increased in the cardiac ventricle after diabetic stroke. Importantly, the NLRP3 inflammasome inhibitor CY-09 restored cardiac function, indicating that the M1-polarized macrophage-NLRP3 inflammasome activation is a pathway underlying the brain-heart interaction after diabetic stroke.

NLRP3 inflammasome as a potential treatment in ischemic stroke concomitant with diabetes.

The NLRP3 (nucleotide-binding oligomerization domain-like receptor [NLR] family pyrin domain-containing 3) inflammasome is a member of the NLR family of innate immune cell sensors. These are crucial regulators of cytokine secretions, which promote ischemic cell death and insulin resistance. This review summarizes recent progress regarding the NLRP3 inflammasome as a potential treatment for ischemic stroke in patients with diabetes, two complicated diseases that often occur together. Stroke worsens glucose metabolism abnormalities, and the outcomes after stroke are more serious for diabetic patients compared with those without diabetes. Inflammation contributes to organ injury after ischemic stroke and diabetes. Recent research has focused on inhibiting the activation of inflammasomes and thus reducing the maturation of proinflammatory cytokines such as interleukin (IL)-1ß and IL-18. Studies suggest that inhibition of NLRP3 prevents or alleviates both ischemic stroke and diabetes. Targeting against the assembly and activity of the NLRP3 inflammasome is a potential and novel therapy for inflammasome-associated diseases, including ischemic stroke concomitant with diabetes.

Postoperative Cognitive Dysfunction Induced by Different Surgical Methods and Its Risk Factors.

The aim of the present study was to compare the effect of different surgical methods on postoperative cognitive function in patients undergoing abdominal surgery, determine the risk factors of postoperative cognitive dysfunction (POCD) by logistic regression, and investigate these risk factors through different surgical methods. A total of 70 patients undergoing selective abdominal surgery were selected into this study. The age of these patients ranged within 32 to 85 years. The cognitive function of these patients was assessed by the mini-mental state examination at one day before the operation, and at the first and seventh day after the operation. The temperature of the tympanic membrane, PETCO2 values, visual analogue scale scores, educational level, and operation time were recorded. Logistic regression analysis was used to analyze related factors of POCD. The incidence rate of perioperative hypothermia in groups O and L were 31.2 and 10.5 per cent, respectively; and the difference was statistically significant (P < 0.05). The difference in visual analogue scale scores at the first and seventh day after the operation between these two groups were statistically significant (P < 0.01). The incidence of POCD in group O was significantly higher than that in group L at the first and seventh day after the operation (P < 0.05). According to logistic regression results, it was found that age, perioperative hypothermia, and postoperative pain were risk factors of POCD. The difference in POCD for the patients undergoing abdominal surgery through different surgical methods was statistically significant, and this was closely correlated to perioperative hypothermia and postoperative pain.

Inhibition of NLRP3 Inflammasome Ameliorates Cerebral Ischemia-Reperfusion Injury in Diabetic Mice.

Sustained activation of NLRP3 inflammasome is closely related to diabetes and stroke. However, it is unknown whether NLRP3 inflammasome plays an essential role in stroke in diabetes. We aim to investigate the effect and the potential mechanism of NLRP3 inflammasome in diabetic mice with cerebral ischemia-reperfusion injury. A type 2 diabetic mouse model was induced by a high-fat diet and streptozotocin (STZ). Diabetic mice received MCC950 (the specific molecule NLRP3 inhibitor) or vehicle 60 minutes before the middle cerebral artery occlusion (MCAO) and reperfusion. MCC950 reduced the neurological deficit score of 24 h after cerebral ischemia reperfusion and improved the 28-day survival rate of cerebral ischemia-reperfusion injury in diabetic mice. Furthermore, we found that the mRNA transcription levels of NLRP3, IL-1ß, and caspase-1 in the core ischemic area were remarkably amplified in diabetic mice with cerebral ischemia-reperfusion injury, whereas this phenomenon was obviously attenuated by MCC950 pretreatment. In conclusion, the NLRP3 inflammasome was involved in the complex diseases of diabetic stroke. MCC950, the NLRP3 specific inhibitor, ameliorated diabetic mice with cerebral ischemia-reperfusion injury and improved the 28-day survival rate during the recovery stage of ischemic stroke.

Prevention of hypothermia by infusion of warm fluid during abdominal surgery.

Perioperative hypothermia can lead to a number of complications for patients after surgery. The aim of this pilot study was to evaluate the efficacy of warm fluids in maintaining normal core temperature during the intraoperative period. We studied 30 American Society of Anesthesiologists (ASA) physical status I or II adult patients who required general anesthesia for abdominal surgery. In the control group (n = 15), fluids were infused at room temperature; in the test group (n = 15), fluids were infused at 37° C. In the control group, core temperature decreased to 35.5 ± 0.3° C during the first 3 hours, and then stabilized at the end of anesthesia. In the test group, core temperature decreased during the first 60 minutes, but increased to 36.9 ± 0.3° C at the end of anesthesia. In the control group, eight patients shivered at grade ≥2. In the test group, none of the patients reached grade ≥2 (P < .01). Infusion of warm fluid is effective in keeping patients nearly normothermic and preventing postanesthetic shivering. It may provide an easy and effective method for prevention of perioperative hypothermia.

[Detection of interferon-induced transmembrane-1 gene expression for clinical diagnosis of colorectal cancer].

OBJECTIVE: To investigate the expression of the interferon-induced transmembrane-1 (IFITM1) gene in colorectal cancer (CRC) tissue and the serum anti-IFITM1 antibody responses of the patients and assess their value in clinical diagnosis of CRC. METHODS: Semi-quantitative RT-PCR was performed to detect IFITM1 mRNA expression in the specimens of normal colonic mucosa, CRC tissue, inflammatory polyps, adenomatous polyps, gastric cancer, esophageal carcinoma and liver cancer tissues. Serum samples were collected from the patients to detect anti-IFITM1 antibody responses using Western blotting. The clinicopathological features of the carcinoma expressing IFITM1 gene were analyzed. RESULTS: IFITM1 mRNA was expressed in 47.4 % (18/38) of the CRC specimens, a rate significantly higher than that in adenomatous polyps [15% (3/20)] and gastric cancer [4.8% (1/21)]; no obvious IFITM1 expression was found in normal colonic mucosa, inflammatory polyp, esophageal carcinoma or liver cancer tissues (P<0.001 or P<0.05). IFITM1 mRNA was strongly expressed in CRC at the expression level of 0.8048-/+0.2273, which was significantly higher than that in adenomatous polyps (0.4447-/+0.0989, P<0.001). No anti-IFITM1 antibody response was detected in healthy human sera, but in the CRC patients, the serum antibody response was detected at the rate of 36.8% (14/38), significantly higher than the rate of 9.5% (2/21) in gastric cancer (P<0.05). No antibody response was detected in esophageal carcinoma, liver cancer, inflammatory polyp or adenomatous polyps. Most of the IFITM1-expressing CRC had a diameter exceeding 5 cm, often invading the serous membrane with metastasis to the lymph nodes and the distant organs; these tumors were identified mostly as well-differentiated adenocarcinoma in Dukes stage C or D. CONCLUSION: IFITM1 gene may play an important role in the pathogenesis, development and metastasis of CRC, and may serve as a potential biomarker for clinical diagnosis of CRC.