Methane ameliorates post-operative cognitive dysfunction by inhibiting microglia NF-κB/MAPKs pathway and promoting IL-10 expression in aged mice

Tryptophan-rich diet and its effects on Htr7+ Tregs in alleviating neuroinflammation and cognitive impairment induced by lipopolysaccharide

BACKGROUND

Neuroinflammation is a vital pathogenic mechanism for neurodegenerative diseases such as Alzheimer's, schizophrenia, and age-related cognitive decline. Regulatory T cells (Tregs) exhibit potent anti-inflammatory properties and can modulate neurodegenerative diseases arising from central nervous system inflammatory responses. However, the role of Tregs in neuroinflammation-related cognitive dysfunction remains unclear. It is highly plausible that Htr7+ Tregs expressing unique genes associated with the nervous system, including the Htr7 gene encoding the serotonin receptor 5-HT7, play a pivotal role.

METHODS

Mice were given a tryptophan-rich diet (with a tryptophan content of 0.6%) or a normal diet (with a tryptophan content of 0.16%). The neuroinflammation-mediated cognitive dysfunction model was established by intracerebroventricular injection of lipopolysaccharide (LPS) in 8-week-old C57BL/6J mice. The activation and infiltration of Tregs were measured using flow cytometry. Primary Tregs were cocultured separately with primary CD8+ T cells and primary microglia for in vitro validation of the impact of 5-HT and 5-HT7 receptor on Tregs. Prior to their transfer into recombination activating gene 1 (Rag1-/-) mice, Tregs were ex vivo transfected with lentivirus to knock down the expression of Htr7.

RESULTS

In this study, the tryptophan-rich diet was found to reverse LPS-induced cognitive impairment and reduce the levels of 5-HT in peripheral blood. The tryptophan-rich diet led to increased levels of 5-HT in peripheral blood, which in turn promoted the proliferation and activation of Htr7+ Tregs. Additionally, the tryptophan-rich diet was also shown to attenuate LPS-mediated neuroinflammation by activating Htr7+ Tregs. Furthermore, 5-HT and 5-HT7 receptor were found to enhance the immunosuppressive effect of Tregs on CD8+ T cells and microglia. In Rag1-/- mice, Htr7+ Tregs were shown to alleviate LPS-induced neuroinflammation and cognitive impairment.

CONCLUSIONS

Our research revealed the ability of Htr7+ Tregs to mitigate neuroinflammation and prevent neuronal damage by suppressing the infiltration of CD8+ T cells into the brain and excessive activation of microglia, thereby ameliorating LPS-induced cognitive impairment. These insights may offer novel therapeutic targets involving Tregs for neuroinflammation and cognitive impairment.

Differential Patterns of Gut and Oral Microbiomes in Hispanic Individuals with Cognitive Impairment

Alzheimer's disease and related dementias (ADRD) have been associated with alterations in both oral and gut microbiomes. While extensive research has focused on the role of gut dysbiosis in ADRD, the contribution of the oral microbiome remains relatively understudied. Furthermore, the potential synergistic interactions between oral and gut microbiomes in ADRD pathology are largely unexplored. This study aims to evaluate distinct patterns and potential synergistic effects of oral and gut microbiomes in a cohort of predominantly Hispanic individuals with cognitive impairment (CI) and without cognitive impairment (NC). We conducted 16S rRNA gene sequencing on stool and saliva samples from 32 participants (17 CI, 15 NC; 62.5% female, mean age = 70.4 ± 6.2 years) recruited in San Antonio, Texas, USA. Correlation analysis through MaAslin2 assessed the relationship between participants' clinical measurements (e.g., fasting glucose and blood cholesterol) and their gut and saliva microbial contents. Differential abundance analysis evaluated taxa with significant differences between CI and NC groups, and alpha and beta diversity metrics assessed within-sample and group compositional differences. Our analyses revealed no significant differences between NC and CI groups in fasting glucose or blood cholesterol levels. However, a clear association was observed between gut microbiome composition and levels of fasting glucose and blood cholesterol. While alpha and beta diversity metrics showed no significant differences between CI and NC groups, differential abundance analysis revealed an increased presence of oral genera such as Dialister , Fretibacterium , and Mycoplasma in CI participants. Conversely, CI individuals exhibited a decreased abundance of gut genera, including Shuttleworthia , Holdemania , and Subdoligranulum , which are known for their anti-inflammatory properties. No evidence was found for synergistic contributions between oral and gut microbiomes in the context of ADRD. Our findings suggest that similar to the gut microbiome, the oral microbiome undergoes significant modifications as individuals transition from NC to CI. Notably, the identified oral microbes have been previously associated with periodontal diseases and gingivitis. These results underscore the necessity for further investigations with larger sample sizes to validate our findings and elucidate the complex interplay between oral and gut microbiomes in ADRD pathogenesis.

Impact of butorphanol versus sufentanil on postoperative cognition and inflammation in elderly: a pilot study

Background

This randomized controlled trial aimed to compare the effects of butorphanol and sufentanil on early post-operative cognitive dysfunction (POCD) and systemic inflammation in older surgical patients.

Methods

Patients (aged 65 years or above) undergoing surgeries with general anesthesia were randomized to either the butorphanol group (40 μg/kg during anesthesia induction) or the sufentanil group (0.4 μg/kg). Cognitive function changes during the perioperative period were assessed using the Mini-Mental State Examination (MMSE) and the Montreal Cognitive Assessment (MoCA) scale up to 3 days after surgery. POCD was defined as a Z-score or composite Z-score greater than 1.96 for both MMSE and MoCA scores. Circulating inflammatory factors, including tumor necrosis factor-alpha (TNF-α), interleukin 1 beta (IL-1β), and interleukin 10 (IL-10), were measured using enzyme-linked immunosorbent assay.

Results

The study included 114 patients (median age: 71 years, 57.7% male). Compared to sufentanil, butorphanol significantly reduced the incidence of POCD on the first (11.5% versus 32.7%, p = 0.017) and third day (3.8% versus 15.4%, p = 0.046) after surgery. Additionally, patients receiving butorphanol had significantly lower circulating levels of TNF-α and IL-1β at the time of discharge from the post-anesthesia care unit and on the first and third day after surgery (p < 0.05 for all comparisons). Furthermore, circulating IL-10 levels were significantly higher in patients receiving butorphanol (p < 0.05 for all comparisons).

Conclusion

Administration of butorphanol during anesthesia induction, as opposed to sufentanil, was associated with a significant reduction in the early incidence of POCD in older surgical patients, possibly attributed to its impact on systemic inflammation.Clinical trial registration: The present study was registered in the China Clinical Trial Center (ChiCTR2300070805, 24/04/2023).

Research progress on the association between MicroRNA and postoperative cognitive dysfunction

Postoperative cognitive dysfunction (POCD) is a significant complication following surgery. The precise mechanisms underlying POCD remain elusive, although it is speculated that they involve central nervous system inflammation, oxidative stress and cellular apoptosis. MicroRNAs (miRNAs), a class of non-coding RNAs widely distributed in eukaryotes, have been implicated in the pathogenesis of neurodegenerative disorders and could potentially impact POCD. This review explores the association between miRNAs and POCD and provides an overview of the progress of current research on miRNAs in the pathogenesis, diagnosis, and treatment of POCD.

Activation of the CD200/CD200R1 axis attenuates neuroinflammation and improves postoperative cognitive dysfunction via the PI3K/Akt/NF-κB signaling pathway in aged mice

BACKGROUND

Postoperative cognitive dysfunction (POCD) is a neurological complication occurring after anesthesia and surgery. Neuroinflammation plays a critical role in the pathogenesis of POCD, and the activation of the cluster of differentiation 200 (CD200)/CD200R1 axis improves neurological recovery in various neurological disorders by modulating inflammation. The aim of this study was to investigate the impact and underlying mechanism of CD200/CD200R1 axis on POCD in aged mice.

METHODS

The model of POCD was established in aged mice. To assess the learning and memory abilities of model mice, the Morris water maze test was implemented. CD200Fc (CD200 fusion protein), CD200R1 Ab (anti-CD200R1 antibody), and 740Y-P (a specific PI3K activator) were used to evaluate the effects of the CD200/CD200R1/PI3K/Akt/NF-κB signaling pathway on hippocampal microglial polarization, neuroinflammation, synaptic activity, and cognition in mice.

RESULTS

It was observed that anesthesia/surgery induced cognitive decline in aged mice, increased the levels of tumor necrosis factor alpha (TNF-α), interleukin (IL)-6, IL-1 β and decreased the levels of postsynaptic density protein 95 (PSD-95), synaptophysin (SYN) in the hippocampus. Moreover, CD200Fc and 740Y-P attenuated neuroinflammation and synaptic deficits and reversed cognitive impairment via the phosphatidylinositol 3-kinase (PI3K)/ protein kinase B (Akt)/nuclear factor-kappa B (NF-κB) signaling pathway, whereas CD200R1 Ab administration exerted the opposite effects. Our results further show that the CD200/CD200R1 axis modulates M1/M2 polarization in hippocampal microglia via the PI3K/Akt/NF-κB signaling pathway.

CONCLUSIONS

Our findings indicate that the activation of the CD200/CD200R1 axis reduces neuroinflammation, synaptic deficits, and cognitive impairment in the hippocampus of aged mice by regulating microglial M1/M2 polarization via the PI3K/Akt/NF-κB signaling pathway.

Effects of Oral β-caryophyllene (BCP) Treatment on Perioperative Neurocognitive Disorders: Attenuation of Neuroinflammation Associated with Microglial Activation and Reinforcement of Autophagy Activity in Aged Mice

Perioperative neurocognitive disorders (PND) are a constellation of cognitive impairments that arise following surgical procedures and anesthesia, with a higher incidence in elderly patients. PND is deeply entwined with microglia-mediated neuroinflammation and disrupted autophagy. β-caryophyllene (BCP) is a natural terpene that occurs widely in dietary plants, and possesses robust anti-inflammatory properties by selectively activating CB2 receptors (CB2R). Accordingly, the present study endeavors to investigate the potential of BCP in ameliorating PND in aged mice, by mitigating hippocampal neuroinflammation and improving autophagy. In this study, an abdominal surgery was utilized to induce perioperative neurocognitive disorders (PND) in aged mice. BCP was administered orally at a dosage of 200 mg/kg for seven consecutive days prior to the scheduled surgery. In order to explore the relationship between BCP and CB2 receptors (CB2R), a co-administration of intraperitoneal injections of the CB2R antagonist AM630 was implemented, 30 minutes preceding the oral gavage of BCP. Postoperative cognitive functions were assessed using Morris water maze (MWM) tests. The extent of hippocampal inflammation was examined by measuring the microglial marker Iba-1 protein levels, Iba-1 and GFAP immunoactivity, as well as IL-1β and IL-6 concentrations. Evaluation of autophagy activity was conducted based on the ratio of LC3B2/LC3B1 and protein levels of Beclin-1, p62, and phospho-mTOR (p-mTOR). After being orally administered BCP, the compromised behavioral performance of abdominal surgical interventions on aged mice was alleviated. This was evident by the extended escape latency, reduced time spent in the target quadrant, and fewer platform crossings observed through MWM testing. While hippocampal CB2R mRNA or protein expression remained unaffected by the abdominal surgical procedure, their levels were significantly upregulated in mice that were administered BCP. Moreover, the oral administration of BCP was able to reduce neuroinflammation in response to microglia activation, as evidenced by the decreased levels of Iba-1 protein and immunoactivity, as well as the reduction of IL-1β and IL-6 concentrations. Additionally, BCP intensified autophagic activity, as detected by increased LC3B2/LC3B1 ratio and Beclin-1 protein levels, coupled with decreased levels of p62 and p-mTOR in the hippocampus of aged mice. Conversely, the treatment of AM630 ameliorated the suppressive effect of BCP triggered by the neuroinflammation caused by microglial activation post-surgery in aged mice (increased Iba-1 protein levels and immunoactivity, accompanied by higher IL-1β and IL-6 concentrations). Furthermore, the pro-autophagy effect of BCP on aged mice following surgery was partially blocked by AM630, culminating in decreased LC3B2/LC3B1 ratio and Beclin-1 protein levels. However, the levels of p62 and p-mTOR remained unchanged by AM630. Our investigation unveils the remarkable therapeutic benefits of oral BCP administration for managing PND in aged mice through the attenuation of neuroinflammation associated with microglial activation and the fortification of autophagy activity. Hence, BCP holds great promise as a formidable candidate englobing various potential physiological mechanisms that would mitigate cognitive decline associated with aging.

Intergenerational Perioperative Neurocognitive Disorder

Accelerated neurocognitive decline after general anesthesia/surgery, also known as perioperative neurocognitive disorder (PND), is a widely recognized public health problem that may affect millions of patients each year. Advanced age, with its increasing prevalence of heightened stress, inflammation, and neurodegenerative alterations, is a consistent contributing factor to the development of PND. Although a strong homeostatic reserve in young adults makes them more resilient to PND, animal data suggest that young adults with pathophysiological conditions characterized by excessive stress and inflammation may be vulnerable to PND, and this altered phenotype may be passed to future offspring (intergenerational PND). The purpose of this narrative review of data in the literature and the authors' own experimental findings in rodents is to draw attention to the possibility of intergenerational PND, a new phenomenon which, if confirmed in humans, may unravel a big new population that may be affected by parental PND. In particular, we discuss the roles of stress, inflammation, and epigenetic alterations in the development of PND. We also discuss experimental findings that demonstrate the effects of surgery, traumatic brain injury, and the general anesthetic sevoflurane that interact to induce persistent dysregulation of the stress response system, inflammation markers, and behavior in young adult male rats and in their future offspring who have neither trauma nor anesthetic exposure (i.e., an animal model of intergenerational PND).

The role of TREM1 in regulating microglial polarization in sevoflurane-induced perioperative neurocognitive disorders

Microglia-mediated neuroinflammatory responses play a key role in perioperative neurocognitive disorders (PND). Triggering receptor expressed on myeloid cells-1 (TREM1) has been shown to be a key regulator of inflammation. However, its role in PND remains largely unknown. This study aimed to evaluate the role of TREM1 in sevoflurane-induced PND. We applied AAV knockdown TREM1 in hippocampal microglia in aging mice. The mice were then subjected to neurobehavioral and biochemical testing after the intervention of sevoflurane. We found that sevoflurane inhalation can cause PND in mice, increase hippocampal TREM1 expression, polarize microglia to M1 type, upregulate TNF-α and IL-1β expression (pro-inflammatory), and inhibit TGF-β and IL-10 expression (anti-inflammatory). Knocking down TREM1 can improve sevoflurane-induced cognitive dysfunction, reduce M1 type marker iNOS, and increase M2 type marker ARG, improving the neuroinflammation. TREM1 is a target for sevoflurane-induced PND prevention.

IL-33/ST2 axis promotes remodeling of the extracellular matrix and drives protective microglial responses in the mouse model of perioperative neurocognitive disorders

Anesthesia and surgery induce cognitive impairment via uncertain mechanisms. Increasing evidence has suggested that microglial activity mediated by IL-33 /ST2 plays a critical role in immune regulation and inflammatory responses. Yet, the implications for microglia activity mediated by IL-33 in perioperative neurocognitive disorders (PND) are not well established. We showed that IL-33 and ST2 were downregulated in the hippocampus after anesthesia and surgery, and the expression of aggrecan, remodeling by microglia, was upregulated. Meanwhile, the expression of pro-inflammatory cytokines (IL-6 and IL-1β) and M1-like microglia marker (iNOS) increased, and the expression of M2-like microglia marker (CD206) decreased. Notably, the administration of IL-33 attenuated neuroinflammation and shifted the polarization of microglia in the hippocampus after anesthesia and surgery. Furthermore, IL-33 treatment rescued the increase of aggrecan, loss of dendritic spines, and impairment of LTP, improving cognitive performance. In conclusion, our study suggests that microglia activity mediated by IL-33/ST2 plays a vital role in cognitive impairments after anesthesia and surgery, which may serve as a therapeutic target for PND.

Targeting neuroinflammation as a preventive and therapeutic approach for perioperative neurocognitive disorders

Perioperative neurocognitive disorders (PND) is a common postoperative complication associated with regional or general anesthesia and surgery. Growing evidence in both patient and animal models of PND suggested that neuroinflammation plays a critical role in the development and progression of this problem, therefore, mounting efforts have been made to develop novel therapeutic approaches for PND by targeting specific factors or steps alongside the neuroinflammation. Multiple studies have shown that perioperative anti-neuroinflammatory strategies via administering pharmacologic agents or performing nonpharmacologic approaches exert benefits in the prevention and management of PND, although more clinical evidence is urgently needed to testify or confirm these results. Furthermore, long-term effects and outcomes with respect to cognitive functions and side effects are needed to be observed. In this review, we discuss recent preclinical and clinical studies published within a decade as potential preventive and therapeutic approaches targeting neuroinflammation for PND.

Network pharmacology-based prediction of active compounds in the Wenyang Jiedu Huayu formula acting on acute-on-chronic liver failure with experimental support in vitro and in vivo

Acute-on-chronic liver failure (ACLF) is characterized by undermined liver function, massive necrosis/apoptosis of hepatocytes, and hepatic inflammatory cell recruitment, leading to multiorgan failure. Traditional Chinese medicine (TCM) has been widely applied in clinical and experimental studies of ACLF. In this study, 23 compounds with 6,386 drug targets were obtained from Wenyang Jiedu Huayu (WYJDHY), and 8,096 genes were identified as ACLF disease targets, among which 3,132 were overlapping co-targets. Expression profile analysis identified 105 DEGs among the co-targets, which were associated with biological activities such as lymphocyte activation, immune response regulation, and pathways such as Th17 cell differentiation and NF-κB signaling. After PPI analysis and network construction, atractylenolide I (AT-1) has been identified as the hub active ingredient of the WYJDHY formula. LPS stimulation inhibited rat hepatocytes’ BRL 3A cell viability, promoted cell apoptosis, increased the levels of ALT, AST, IL-6, and VCAM-1 within the culture medium, and activated NF-κB signaling, whereas AT-1 treatment significantly attenuated LPS-induced toxicity on BRL 3A cells. Furthermore, the NF-κB signaling inhibitor PDTC exerted effects on LPS-stimulated BRL 3A cells similar to those of AT-1, and the combination of PDTC and AT-1 further attenuated LPS-induced toxicity on BRL 3A cells. In vivo, AT-1 alone or with PDTC improved the symptoms and local inflammation in ACLF model rats. In conclusion, 23 active ingredients of six herbs in the WYJDHY formula were retrieved, and 105 co-targets were differentially expressed in ACLF. AT-1 exerts protective effects on LPS-stimulated hepatocytes and ACLF rats, possibly by inhibiting the NF-κB pathway.

IL-33 Alleviates Postoperative Cognitive Impairment by Inhibiting Hippocampal Inflammation and Upregulating Excitatory Synaptic Number in Aged Mice

Delayed neurocognitive recovery (dNCR), a postoperative complication that occurs in elderly patients, still lacks effective treatment. Interleukin-33 (IL-33) has been proved to modulate neuroinflammation and synaptic plasticity, among other effects, but the role of IL-33 in dNCR is not clear. We established a dNCR model in aged mice by laparotomy under sevoflurane anesthesia. Cognition was evaluated by Morris water maze (MWM) and fear conditioning test (FCT). Immunofluorescence was used to detect the density of IL-33 and glial fibrillary acidic protein (GFAP) co-localization, ionized calcium-binding adapter molecule 1, vesicular glutamate transporter 1 (vGlut1) and postsynaptic density protein-95 (PSD95) co-localization in the hippocampus. IL-33, GFAP, vGlut1 and PSD95 were tested by Western blotting. Enzyme-linked immunosorbent assay was used to detect the levels of tumor necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β) and IL-10. Surgery/anesthesia reduced the level of IL-33 in the hippocampus. Intraperitoneal injection of 200 ng IL-33 per mouse significantly decreased the latency to the platform and increased the number of platform crossings and the target quadrant dwell time in MWM, while increasing the freezing time in the context test of FCT. Furthermore, IL-33 inhibited microglial activation and the release of TNF-α and IL-1β while upregulating the markers of excitatory synapses vGlut1 and PSD95. Our findings indicated that IL-33 improved cognition by inhibiting the hippocampal inflammatory response and upregulating the number of excitatory synapses. Therefore, IL-33 is a potential drug for the treatment of dNCR.

PEX5R/Trip8b-HCN2 channel regulating neuroinflammation involved in perioperative neurocognitive disorders

Background

Clinical and animal studies demonstrated that neuroinflammation from anesthesia (sevoflurane) is the main contributor to cause perioperative neurocognitive disorders (PND). Recently, it was reported that microglia respond to hyperpolarization-activated cyclic nucleotide-gated (HCN) channels, which was the target of sevoflurane. Whether HCN channels are involved in the induction of neuroinflammation after sevoflurane exposure is still unclear.

Results

Sevoflurane exposure had increased cognitive dysfunction and anxiety-like behaviors in rats. Rats inhaled with sevoflurane had activated microglia and increased neuroinflammation (IL-1β, IL-6, and TNF-α) in the hippocampus. RNA sequencing identified 132 DEGs (86 up-regulated and 46 down-regulated DEGs [differentially expressed genes]) in the hippocampus of PND rats. RNA-sequencing also uncovered that sevoflurane exposure down-regulates HCN2 expression. Pathway and process enrichment analysis suggests DEGs are mainly enriched in regulation of system process, positive regulation of glutamate secretion, secretion, regulation of synaptic transmission, regulation of nervous system process, behavior, negative regulation of sodium ion transport, and learning or memory. We validated that sevoflurane exposure can down-regulate the levels of PEX5R/Trip8b (an interaction partner and auxiliary subunit of HCN channels) and HCN1-4 channels in the hippocampus of PND rats. We used immunofluorescence staining to identify that HCN2 co-labels with neurons (Neun), astrocytes (GFAP), and microglia (iba1). We observed that the co-labeling of HCN2 with neurons or microglia decreased in the hippocampus and cortex after sevoflurane exposure. Blocking HCN2 by ZD7288 treatment further activated microglia and aggravated sevoflurane exposure-induced anxiety-like behavior, cognitive impairment, and neuroinflammation.

Conclusions

We concluded that sevoflurane exposure can induce an increased level of neuroinflammation, microglial activation, cognitive dysfunction, and anxiety-like behaviors in rats. HCN2 channel, as the target of sevoflurane action, mediates this process. HCN2 might be a target for the treatment and prevention of sevoflurane-induced PND.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13578-022-00892-6.

Malvidin protects against lipopolysaccharide-induced acute liver injury in mice via regulating Nrf2 and NLRP3 pathways and suppressing apoptosis and autophagy

Sepsis-related acute liver injury (ALI) is a fatal disease associated with many complications. Recent studies indicate that malvidin, an active flavonoid, has multiple bioactivities including anti-oxidant and anti-inflammation. However, the protective roles of malvidin against LPS-induced ALI are unknown. The purpose of this research is to explore whether malvidin has biological activities on LPS-induced ALI in mice and the underlying mechanisms. Male C57 mice were injected intraperitoneally with malvidin for five days and the mice were euthanized 6 hours after LPS (10 mg/kg body weight) intraperitoneal injection. Multiple methods of H&E staining, biochemical kits, qRT-PCR assay, western blotting analysis, TUNEL and transmission electron microscope (TEM) were used. Results showed that decreased ALT, AST levels and alleviated histopathological damage of liver tissue were observed in malvidin pretreatment group in mice. Then, malvidin prevented LPS-induced reduction of antioxidant enzyme activities such as superoxide dismutase (SOD), glutathione peroxidase (GSH-PX) and catalase (CAT) via up-regulating nuclear factor E2-related factor2 (Nrf2) pathway. In addition, in malvidin pretreatment groups, mRNA levels of pro-inflammatory cytokines (TNF-α，IL-1β, IL-6) and protein levels of NOD-like receptor protein 3 (NLRP3) inflammasome in the liver were significantly down-regulated. We also found that the malvidin could reduce the expression of apoptosis key protein and TUNEL-labeled apoptotic hepatocytes. Furthermore, malvidin inhibited the protein expression of ATG5, p62 and the ratio of LC3-II/LC3-I. In conclusion, our study firstly suggests that malvidin is a potentially protective agent against LPS-induced ALI through up-regulating Nrf2 signaling pathway, suppressing NLRP3 inflammasome and inhibiting apoptosis and autophagy.

Progress in the correlation of postoperative cognitive dysfunction and Alzheimer's disease and the potential therapeutic drug exploration

Postoperative cognitive dysfunction (POCD) is a decrease in mental capacity that can occur days to weeks after a medical procedure and may become permanent and rarely lasts for a longer period of time. With the continuous development of research, various viewpoints in academic circles have undergone subtle changes, and the role of anesthesia depth and anesthesia type seems to be gradually weakened; Alzheimer's disease (AD) is a latent and progressive neurodegenerative disease in the elderly. The protein hypothesis and the synaptic hypothesis are well-known reasons. These changes will also lead to the occurrence of an inflammatory cascade. The exact etiology and pathogenesis need to be studied. The reasonable biological mechanism affecting brain protein deposition, neuroinflammation, and acetylcholine-like effect has a certain relationship between AD and POCD. Whereas there is still further uncertainty about the mechanism and treatment, and it is elusive whether POCD is a link in the continuous progress of AD or a separate entity, which has doubts about the diagnosis and treatment of the disease. Therefore, this review is based on the current common clinical characteristics of AD and POCD, and pathophysiological research, to search for their common points and explore the direction and new strategies for future treatment.

Vitamin D3 Protects Mice from Diquat-Induced Oxidative Stress through the NF-κB/Nrf2/HO-1 Signaling Pathway

Vitamin D3, as an indispensable and fat-soluble micronutrient, plays an important role in the health of humans and animals. At present, studies are focusing on the calcium absorption and immunoregulation function of vitamin D3; this study was aimed at exploring the antioxidative stress ability of vitamin D3 on diquat-induced intestinal dysfunction of ICR mice and the underlying mechanism. The results showed that oral gavage of vitamin D3 daily significantly improved the body weight gain and immune organ index and significantly reverted the abnormal changes of ALT, AST, SOD, GSH-Px, T-AOC, and MDA in the serum and jejunum induced by diquat. The addition of vitamin D3 also significantly reduced the concentration of DAO, D-LA, and certain proinflammatory cytokines in serum. Moreover, vitamin D3 improved the pathological morphology of the duodenum, jejunum, colon, liver, and kidney tissues, and it also largely attenuated the degree of inflammatory infiltration of macrophages and cell apoptotic index of jejunal epithelial tissue induced by diquat. The results demonstrated that vitamin D3 significantly recovered the intestinal barrier injury by enhancing the expression of mucins and tight junction proteins in the jejunum. In addition, the results indicated that vitamin D3 could significantly reduce the phosphorylation level of NF-κB (p65) and enhance the expression of Nrf2 and HO-1 in the jejunum compared with the diquat-induced group. This study suggested that oral administration of vitamin D3 can protect mice against oxidative damage by inhibiting the phosphorylation level of NF-κB (p65) and activating Nrf2-related signaling pathways.

Protective role of dexmedetomidine against sevoflurane-induced postoperative cognitive dysfunction via the microRNA-129/TLR4 axis

The involvement of Dexmedetomidine (Dex) has been indicated in postoperative cognitive dysfunction (POCD), while the mechanism is not well characterized. This study estimated the mechanism of Dex in POCD. Rats were anesthetized with sevoflurane (SEV) to evoke POCD and then subjected to Morris water maze test to detect the cognitive and behavioral function. Then, the damage of hippocampus and cortex, and apoptosis and activity of neurons were examined. Microarray analysis was performed to screen out the differentially expressed microRNAs (miRs) in rats after Dex treatment. The cognitive and behavioral functions and neuronal activity of rats were detected after miR-129 antagomir injection. The target of miR-129 was predicted. The levels of TLR4 and NF-κB p65 in hippocampus and cortex were measured. Dex treatment alleviated SEV-induced behavior and cognitive impairments in rats, promoted neuronal activity and hindered neuronal apoptosis. After treatment with Dex, miR-129 expression was elevated in brain tissues, and the neuroprotection of Dex on POCD rats was partially annulled after injection of miR-129 antagomir. Furthermore, miR-129 targeted TLR4 and prevented the phosphorylation of NF-κB p65. In summary, Dex ameliorated SEV-induced POCD by elevating miR-129 and inhibiting TLR4 and NF-κB p65 phosphorylation. This study may shed new lights on POCD treatment.

Clemastine Ameliorates Perioperative Neurocognitive Disorder in Aged Mice Caused by Anesthesia and Surgery

Perioperative neurocognitive disorder (PND) leads to progressive deterioration of cognitive function, especially in aged patients. Demyelination is closely associated with cognitive dysfunction. However, the relationship between PND and demyelination remains unclear. Here we showed that demyelination was related to the pathogenesis of PND. Clemastine, an antihistamine with potency in remyelination, was predicted to have a potential therapeutic effect on PND by next-generation sequencing and bioinformatics in our previous study. In the present study, it was given at 10 mg/kg per day for 2 weeks to evaluate the effects on PND in aged mice. We found that clemastine ameliorated PND and reduced the expression levels of inflammatory factors such as tumor necrosis factor alpha (TNF-α) and interleukin-1 beta (IL-1β). Further investigation suggested clemastine increased the expression of oligodendrocyte transcription factor 2 (OLIG2) and myelin basic protein (MBP) to enhance remyelination by inhibiting the overactivation of the WNT/β-catenin pathway. At the same time, the expression of post-synaptic density protein 95 (PSD95, or DLG4), brain-derived neurotrophic factor (BDNF), synaptosomal-associated protein 25 (SNAP25) and neuronal nuclei (NEUN) were also improved. Our results suggested that clemastine might be a therapy for PND caused by anesthetic and surgical factors in aged patients.

The role of meningeal populations of type II innate lymphoid cells in modulating neuroinflammation in neurodegenerative diseases

Recent research into meningeal lymphatics has revealed a never-before appreciated role of type II innate lymphoid cells (ILC2s) in modulating neuroinflammation in the central nervous system (CNS). To date, the role of ILC2-mediated inflammation in the periphery has been well studied. However, the exact distribution of ILC2s in the CNS and therefore their putative role in modulating neuroinflammation in neurodegenerative diseases such as Alzheimer's disease (AD), multiple sclerosis (MS), Parkinson's disease (PD), and major depressive disorder (MDD) remain highly elusive. Here, we review the current evidence of ILC2-mediated modulation of neuroinflammatory cues (i.e., IL-33, IL-25, IL-5, IL-13, IL-10, TNFα, and CXCL16-CXCR6) within the CNS, highlight the distribution of ILC2s in both the periphery and CNS, and discuss some challenges associated with cell type-specific targeting that are important for therapeutics. A comprehensive understanding of the roles of ILC2s in mediating and responding to inflammatory cues may provide valuable insight into potential therapeutic strategies for many dementia-related disorders.

JNK inhibition alleviates delayed neurocognitive recovery after surgery by limiting microglia pyroptosis

Delayed neurocognitive recovery (dNCR) is a prevalent complication after surgery in older adults. Neuroinflammation plays a pivotal role in the pathogenesis of dNCR. Recently,compelling evidence suggests that theinvolvement of microglia pyroptosis in the regulation of neuroinflammation in neurologicaldiseases. Nevertheless, the exact role of microglia pyroptosis in dNCR remains elusive. In the study, in vitro and in vivo models of dNCR were used to examine the potential effects of the mitogen‑activated protein kinase signaling pathway on Nod-like receptor protein 3 (NLRP3) inflammasome-mediated microglia pyroptosis and cognitive deficits following surgery. In vivo, we observed surgery-induced upregulation of phosphorylated (p)-c-Jun N-terminal kinases (JNK) in microglia and subsequently NLRP3 inflammasome activation, pyroptosis, and inflammatory cytokines release in mice hippocampus. Interestingly, JNK inhibitor SP600125 significantly attenuated surgery-induced cognitive impairments through inhibiting pyroptosis, inflammatory responses, and reducing immunoreactivity of NLRP3 and gasdermin D N terminus (GSDMD-N) in hippocampal microglia. In vitro, NLRP3 inflammasome- and pyroptosis-associated proteins and immunoreactivity of NLRP3, GSDMD-N, and interleukin-1β were activated in BV2 microglial cells following lipopolysaccharide (LPS) stimulation. These effects were significantly suppressed in BV2 cells by SP600125 treatment. Furthermore, treatment with NLRP3 specific inhibitor, MCC950, attenuated microglia pyroptosis induced by LPS, but did not rescue LPS-induced increased expression of p-JNK. These results indicate that the JNK pathway is largely upstream of the NLRP3 inflammasome, which exerts a crucial regulatory impact on microglia pyroptosis and inflammatory responses, thus providing a promising avenue to prevent dNCR.

Therapeutic effect of methane and its mechanism in disease treatment

Methane is the simplest hydrocarbon, consisting of one carbon atom and four hydrogen atoms. It is abundant in marsh gas, livestock rumination, and combustible ice. Little is known about the use of methane in human disease treatment. Current research indicates that methane is useful for treating several diseases including ischemia and reperfusion injury, and inflammatory diseases. The mechanisms underlying the protective effects of methane appear primarily to involve anti-oxidation, anti-inflammation, and anti-apoptosis. In this review, we describe the beneficial effects of methane on different diseases, summarize possible mechanisms by which methane may act in these conditions, and discuss the purpose of methane production in hypoxic conditions. Then we propose several promising directions for the future research.

Treatment with Histone Deacetylase Inhibitor Attenuates Peripheral Inflammation-Induced Cognitive Dysfunction and Microglial Activation: The Effect of SAHA as a Peripheral HDAC Inhibitor

It has been demonstrated that peripheral inflammation induces cognitive dysfunction. Several histone deacetylase (HDAC) inhibitors ameliorate cognitive dysfunction in animal models of not only peripheral inflammation but also Alzheimer's disease. However, it is not clear which HDAC expressed in the central nervous system or peripheral tissues is involved in the therapeutic effect of HDAC inhibition on cognitive dysfunction. Hence, the present study investigated the effect of peripheral HDAC inhibition on peripheral inflammation-induced cognitive dysfunction. Suberoylanilide hydroxamic acid (SAHA), a pan-HDAC inhibitor that is mainly distributed in peripheral tissues after intraperitoneal administration, was found to prevent peripheral inflammation-induced cognitive dysfunction. Moreover, pretreatment with SAHA dramatically increased mRNA expression of interleukin-10, an anti-inflammatory cytokine, in peripheral and central tissues and attenuated peripheral inflammation-induced microglial activation in the CA3 region of the hippocampus. Minocycline, a macrophage/microglia inhibitor, also ameliorated cognitive dysfunction. Furthermore, as a result of treatment with liposomal clodronate, depletion of peripheral macrophages partially ameliorated the peripheral inflammation-evoked cognitive dysfunction. Taken together, these findings demonstrate that inhibition of peripheral HDAC plays a critical role in preventing cognitive dysfunction induced by peripheral inflammation via the regulation of anti-inflammatory cytokine production and the inhibition of microglial functions in the hippocampus. Thus, these findings could provide support for inhibition of peripheral HDAC as a novel therapeutic strategy for inflammation-induced cognitive dysfunction.

Galectin-1 ameliorates perioperative neurocognitive disorders in aged mice

Introduction

The incidence of perioperative neurocognitive disorders (PND) is higher in the elderly patients undergoing surgery. Microglia activation‐mediated neuroinflammation is one of the hallmarks of PND. Galectin‐1 has been identified as a pivotal modulator in the central nervous system (CNS), while the role of galectin‐1 in PND induced by microglia‐mediated neuroinflammation is still undetermined.

Methods

An exploratory laparotomy model anesthetized with isoflurane was employed to investigate the role of galectin‐1 on PND in aged mice. Open field test and Morris water maze were used to test the cognitive function 3‐ or 7‐days post‐surgery. The activation of microglia in the hippocampus of aged mice was tested by immunohistochemistry. Western blot, enzyme‐linked immunosorbent assay (ELISA), and quantitative real‐time polymerase chain reaction (qRT‐PCR) were employed to elucidate the underlying mechanisms.

Results

Galectin‐1 attenuated the cognitive dysfunction induced by surgery in aged mice and inhibited microglial activity. Moreover, galectin‐1 decreased the expression level of inflammatory proteins (interleukin‐1β, interleukin‐6, and tumor necrosis factor‐α), and prevented neuronal loss in the hippocampus. Galectin‐1 inhibited the inflammation of BV2 microglial cells induced by lipopolysaccharide via decreasing the translocation of NF‐κB p65 and c‐Jun, while this kind of inhibition was rescued when overexpressing IRAK1.

Conclusion

Our findings provide evidence that galectin‐1 may inhibit IRAK1 expression, thus suppressing inflammatory response, inhibiting neuroinflammation, and improving ensuing cognitive dysfunction. Collectively, these findings unveil that galectin‐1 may elicit protective effects on surgery‐induced neuroinflammation and neurocognitive disorders.

The Role of Microglia in Perioperative Neurocognitive Disorders

Perioperative neurocognitive disorder (PND) is a common phenomenon associated with anesthesia and surgery and has been frequently described in the elderly and susceptible individuals. Microglia, which are the brain’s major resident immune cells, play critical roles in maintaining neuronal homeostasis and synaptic plasticity. Accumulating evidence suggests microglial dysfunction occurring after anesthesia and surgery might perturb neuronal function and induce PND. This review aims to provide an overview of the involvement of microglia in PND to date. Possible cellular and molecular mechanisms regarding the connection between microglial activation and PND are discussed.

Methane Alleviates Inflammation and Apoptosis of Dextran Sulfate Sodium-Induced Inflammatory Bowel Diseases by Inhibiting Toll-Like Receptor 4 (TLR4)/Myeloid Differentiation Factor 88 (MyD88)/Nuclear Translocation of Nuclear Factor-κB (NF-κB) and Endoplasmic Reticulum Stress Pathways in Mice

Background

Inflammatory bowel diseases (IBDs) are chronic idiopathic diseases with increased occurrence and recurrence rates. The aim of this study was to explore whether methane-rich saline (MRS) would be beneficial to IBD.

Material/Methods

Dextran sulfate sodium (DSS) was utilized to establish an IBD model. Male C57BL/6J mice were randomly grouped as follows: the control group, the DSS+NS group, the DSS+5-ASA group, the DSS+MRS (1) and DSS+MRS (10) groups. Seven days after model induction, blood and colon tissues were collected to assess the treatment effects.

Results

The DSS+MRS (10) group showed obviously reduced weight loss, disease activity index, and spleen index. The isolated colon samples had a notably longer length, less thickness and weight, and better macroscopic score with MRS treatment compared with the DSS+NS group. Additionally, assessment of morphological impairment revealed a milder and lower microscopic score in the DSS+MRS (10) group, consistent with the myeloperoxidase (MPO) results. The inflammation-related molecules levels were dramatically reduced by MRS. MRS also significantly reduced oxidative stress related proteins. In addition, apoptotic cells were visually decreased in the DSS+MRS (10) group, in which the pro-apoptotic molecules Bax and cleaved caspase-3 were reduced, whereas the level of Bcl-2 was increased. Furthermore, MRS markedly decreased the TLR4, MyD88, p-NF-κB p65, p-IKKαβ, and p-IκBα, and increased IL-10, p-JAK1, and p-STAT3 expression levels. Proteins involved in endoplasmic reticulum stress (ERS) were also notably reduced under MRS treatment.

Conclusions

MRS exerts protective effects on DSS-induced IBD via inhibiting inflammatory reaction, promoting anti-inflammatory capacity, suppressing oxidative stress, and ameliorating apoptosis.

Hippocampal microglial activation triggers a neurotoxic-specific astrocyte response and mediates etomidate-induced long-term synaptic inhibition

Background

Accumulating evidence has highlighted the importance of microglial and astrocyte responses in the pathological development of postoperative cognitive dysfunction (POCD). However, the mechanisms involved are not well understood.

Methods

A perioperative neurocognitive disorders (PND) mouse model was generated by administering etomidate, and cognitive function was assessed using the Morris water maze and novel object recognition tests. Excitatory and inhibitory postsynaptic currents were recorded to analyze neuronal activity. In addition, microglia and astrocytes were isolated by magnetic-activated cell sorting, and genes that were activated in these cells were identified using quantitative polymerase chain reaction.

Results

We observed dramatic cognitive impairment at 1 and 3 weeks after etomidate was administered to 18 month-old mice. Microglia and astrocytes isolated from the hippocampus showed significant microglial activation during the early pathological stage (i.e., 1 week after etomidate injection) and an A1-specific astrocyte response during the late pathological stage (i.e., 3 weeks after etomidate injection). Furthermore, when microglia were eliminated before etomidate was injected, the A1-specific astrocyte activation response was significantly reduced, and cognitive function improved. However, when microglia were eliminated after etomidate application, astrocyte activation and cognitive function were not significantly altered. In addition, activating microglia immediately after a sedative dose of etomidate was injected markedly increased A1-specific astrocyte activation and cognitive dysfunction.

Conclusions

A1-specific astrocyte activation is triggered by activated microglia during the initial pathological stage of PND and induces long-term synaptic inhibition and cognitive deficiencies. These results improve our understanding of how PND develops and may suggest therapeutic targets.

Glycogen synthase kinase-3 as a key regulator of cognitive function

Glycogen synthase kinase-3 (GSK-3) is a highly conserved and multifunctional serine/threonine protein kinase widely distributed in eukaryotic cells. GSK-3 is originally thought to be an enzyme that regulates glycogen synthesis. It was subsequently found that GSK-3 influences many critical cellular functions, such as cell structure, neural plasticity, gene expression, and neuronal survival. Recently, GSK-3 has been found to be associated with cognition, and its dysregulation leads to cognitive impairments in many diseases, including Alzheimer's disease, diabetes, depression, Parkinson's disease, and others. In this review, we summarized the current knowledge about the structure of GSK-3, the regulation of GSK-3 activity, and its role in cognitive function and cognitive-related disease.

Acetate attenuates perioperative neurocognitive disorders in aged mice

Perioperative neurocognitive disorders are common in elderly patients who have undergone surgical procedures. Neuroinflammation induced by microglial activation is a hallmark of these neurological disorders. Acetate can suppress inflammation in the context of inflammatory diseases. We employed an exploratory laparotomy model with isoflurane anesthesia to study the effects of acetate on perioperative neurocognitive disorders in aged mice. Neurocognitive function was assessed with open-field tests and Morris water maze tests 3 or 7 days post-surgery. Acetate ameliorated the surgery-induced cognitive deficits of aged mice and inhibited the activation of IBA-1, a marker of microglial activity. Acetate also reduced expression of inflammatory proteins (tumor necrosis factor-α, interleukin-1β and interleukin-6), oxidative stress factors (NADPH oxidase 2, inducible nitric oxide synthase and reactive oxygen species), and signaling molecules (nuclear factor kappa B and mitogen-activated protein kinase) in the hippocampus. BV2 microglial cells were used to verify the anti-inflammatory effects of acetate in vitro. Acetate suppressed inflammation in lipopolysaccharide-treated BV2 microglial cells, but not when GPR43 was silenced. These results suggest that acetate may bind to GPR43, thereby inhibiting microglial activity, suppressing neuroinflammation, and preventing memory deficits. This makes acetate is a promising therapeutic for surgery-induced neurocognitive disorders and neuroinflammation.

The Investigation of Hippocampus-Dependent Cognitive Decline Induced by Anesthesia/Surgery in Mice Through Integrated Behavioral Z-Scoring

Objective

Patients undergoing major surgeries may experience certain cognitive decline, which is known as postoperative delirium (POD) or postoperative cognitive dysfunction (POCD). We employed integrated behavioral Z-scoring introduced by Guilloux et al. (2011) to investigate the effects of fracture fixation under anesthesia on hippocampus-dependent memory in mice.

Methods

ICR mice (12-14 months) underwent stabilized tibial fracture operation under sevoflurane anesthesia. They were subjected to a battery of successive hippocampus-dependent tests following surgery, including open field test (OF), novel object recognition (NOR), fear conditioning test (FC), and Morris water maze (MWM). The integrated behavioral Z-scoring was applied to assess the hippocampus-dependent memory after anesthesia/surgery, and the association between the integrated behavioral Z-scores and hippocampal pro-inflammatory cytokines was explored.

Results

Mice after anesthesia/surgery were found to have impaired hippocampus-dependent memory in NOR, FC, and MWM but with different degrees in these aspects as represented by P-value and effect size. The integrated memory Z-scores based on principal parameters of the above three tests can reduced the variability and increase the comprehensiveness of behavioral results. However, we found no statistic associations between hippocampal pro-inflammatory cytokines and the integrated Z-scores, as the elevated cytokines quickly return to normal on postoperative day 3 and/or day 7.

Conclusion

The integrated Z-score methodology could facilitate the interpretation of the anesthesia/surgery induced cognitive decline in mice and robustly quantify the behavioral phenotyping of hippocampus-dependent memory.

The δ-Opioid Receptor Differentially Regulates MAPKs and Anti-inflammatory Cytokines in Rat Kidney Epithelial Cells Under Hypoxia

Hypoxic injury is one of the most important factors in progressive kidney disorders. Since we have found that δ-opioid receptor (DOR) is neuroprotective against hypoxic stress through a differential regulation of mitogen-activated protein kinases (MAPKs) and anti-inflammatory cytokines, we asked if DOR that is highly expressed in the kidney can modulate renal MAPKs and anti-inflammatory cytokines under hypoxia. We exposed cultured rat kidney epithelial cells (NRK-52E) to prolonged hypoxia (1% O₂) with applications of specific DOR agonist or/and antagonist to examine if DOR affects hypoxia-induced changes in MAPKs and anti-inflammatory cytokines. The results showed that endogenous DOR expression remained unchanged under hypoxia, while DOR activation with UFP-512 (a specific DOR agonist) reversed the hypoxia-induced up-regulation of ERK1/2 and p38 phosphorylation. DOR inhibition with naltrindole had no appreciable effect on the hypoxia-induced changes in ERK1/2 phosphorylation, but increased p38 phosphorylation. DOR inhibition with naltrindole attenuated the effects of DOR activation on the changes in ERK1/2 and p38 phosphorylation in hypoxia. Moreover, DOR activation/inhibition differentially affected the expression of transcriptional repressor B-cell lymphoma 6 (Bcl-6), anti-inflammatory cytokines tristetraprolin (TTP), and interleukin-10 (IL-10). Taken together, our novel data suggest that DOR activation differentially regulates ERK1/2, p38, Bcl-6, TTP, and IL-10 in the renal cells under hypoxia.

Autophagy Dysfunction and mTOR Hyperactivation Is Involved in Surgery: Induced Behavioral Deficits in Aged C57BL/6J Mice

Autophagy is crucial for cell survival, development, division, and homeostasis. The mammalian target of rapamycin (mTOR), which is the foremost negative controller of autophagy, plays a key role in many endogenous processes. The present study investigated whether rapamycin can ameliorate surgery-induced cognitive deficits by inhibiting mTOR and activating autophagy in the hippocampus. Both adult and aged C57BL/6J mice received an intraperitoneal injection of rapamycin (10 mg/kg/day) for 5 days per week for one and a half months. Mice were then subjected to partial hepatectomy under general anesthesia. Behavioral performance was assessed on postoperative days 3, 7, and 14. Hippocampal autophagy-related (Atg)-5, phosphorylated mTOR, and phosphorylated p70S6K were examined at each time point. Brain derived neurotrophic factor (BDNF), synaptophysin, and tau hyperphosphorylation (T396) in the hippocampus were also examined. Surgical trauma and anesthesia exacerbated spatial learning and memory impairment in aged mice on postoperative days 3 and 7. Following partial hepatectomy, the levels of phosphorylated mTOR, phosphorylated 70S6K, and phosphorylated tau were all increased in the hippocampus. A corresponding decline in BDNF and synaptophysin were observed. Rapamycin treatment restored autophagy function, attenuated phosphorylation of tau protein, and increased BDNF and synaptophysin expression in the hippocampus of surgical mice. Furthermore, surgery and anesthesia induced spatial learning and memory impairments were also reversed by rapamycin treatment. Autophagy impairments and mTOR hyperactivation were detected along with surgery-induced behavioral deficits. Inhibiting the mTOR signaling pathway with rapamycin successfully ameliorated surgery-related cognitive impairments by sustaining autophagic degradation, inhibiting tau hyperphosphorylation, and increasing synaptophysin and BDNF expression.

Methane and Inflammation - A Review (Fight Fire with Fire)

Mammalian methanogenesis is regarded as an indicator of carbohydrate fermentation by anaerobic gastrointestinal flora. Once generated by microbes or released by a non-bacterial process, methane is generally considered to be biologically inactive. However, recent studies have provided evidence for methane bioactivity in various in vivo settings. The administration of methane either in gas form or solutions has been shown to have anti-inflammatory and neuroprotective effects in an array of experimental conditions, such as ischemia/reperfusion, endotoxemia and sepsis. It has also been demonstrated that exogenous methane influences the key regulatory mechanisms and cellular signalling pathways involved in oxidative and nitrosative stress responses. This review offers an insight into the latest findings on the multi-faceted organ protective activity of exogenous methane treatments with special emphasis on its versatile effects demonstrated in sepsis models.

The potential mechanism of postoperative cognitive dysfunction in older people

Postoperative cognitive dysfunction (POCD) is a common disorder following surgery, which seriously threatens the quality of patients' life, especially the older people. Accumulating attention has been paid to POCD worldwide in pace with the popularization of anesthesia/surgery. The development of medical humanities and rehabilitation medicine sets higher demands on accurate diagnosis and safe treatment system of POCD. Although the research on POCD is in full swing, underlying pathogenesis is still inconclusive due to these conflicting results and controversial evidence. Generally, POCD is closely related to neuropsychiatric diseases such as dementia, depression and Alzheimer's disease in molecular pathways. Researchers have come up with various hypotheses to reveal the mechanisms of POCD, including neuroinflammation, oxidative stress, autophagy disorder, impaired synaptic function, lacking neurotrophic support, etc. Recent work focused on molecular mechanism of POCD in older people has been thoroughly reviewed and summed up here, concerning the changes of peripheral circulation, pathological pathways of central nervous system (CNS), the microbiota-gut-brain axis and the related brain regions. Accordingly, this article provides a better perspective to understand the development situation of POCD in older people, which is conductive to uncover the pathological mechanism and exploit reasonable treatment strategy of POCD.

Dexmedetomidine Attenuates Neuroinflammation In LPS-Stimulated BV2 Microglia Cells Through Upregulation Of miR-340

Background

Dexmedetomidine (Dex) was reported to exhibit anti-inflammatory effect in the nervous system. However, the mechanism by which Dex exhibits anti-inflammation effects on LPS-stimulated BV2 microglia cells remains unclear. Thus, this study aimed to investigate the role of Dex in LPS-stimulated BV2 cells.

Methods

The BV2 cells were stimulated by lipopolysaccharides (LPS). BV2 cells were infected with short-hairpin RNAs targeting NF-κB (NF-κB-shRNAs) and NF-κB overexpression lentivirus, respectively. In addition, miR-340 mimics or miR-340 inhibitor was transfected into BV2 cells, respectively. Meanwhile, the dual-luciferase reporter system assay was used to explore the interaction of miR-340 and NF-κB in BV2 cells. CCK-8 was used to detect the viability of BV2 cells. In addition, Western blotting was used to detect the level of NF-κB in LPS-stimulated BV2 cells. The levels of TNF-α, IL-6, IL-1β, IL-2, IL-12, IL-10 and MCP-1 in LPS-stimulated BV2 cells were measured with ELISA.

Results

The level of miR-340 was significantly upregulated in Dex-treated BV2 cells. Meanwhile, the level of NF-κB was significantly increased in BV2 cells following infection with lenti-NF-κB, which was markedly reversed by Dex. LPS markedly increased the expression of NF-κB and proinflammatory cytokines in BV2 cells, which were reversed in the presence of Dex. Moreover, miR-340 mimics enhanced the anti-inflammatory effects of Dex in LPS-stimulated BV2 cells via inhibiting NF-κB and proinflammatory cytokines. Furthermore, Dex obviously inhibited LPS-induced phagocytosis in BV2 cells.

Conclusion

Taken together, our results suggested that Dex might exert anti-inflammatory effects in LPS-stimulated BV2 cells via upregulation of miR-340. Therefore, Dex might serve as a potential agent for the treatment of neuroinflammation.

Protective Effect of Methane-Rich Saline on Acetic Acid-Induced Ulcerative Colitis via Blocking the TLR4/NF-κB/MAPK Pathway and Promoting IL-10/JAK1/STAT3-Mediated Anti-inflammatory Response

Ulcerative colitis (UC) is an inflammation-related disease involved in uncontrolled inflammation and oxidative stress and is characterized by high recurrence and relapse risk. As a rising star in gas medicine, methane owns the properties of anti-inflammation, antioxidation, and antiapoptosis. Based on the possible mechanism, we aimed to investigate the effect of methane on UC. Methane-rich saline (MRS) was introduced here, and UC was induced by acetic acid. All the C57BL/6 mice were allocated into groups as follows: control group, colitis model group, colitis treated with salazosulfapyridine (SASP) group, and colitis treated with MRS (1 or 10 ml/kg) groups. Tissue damage, the degree of inflammation, oxidative stress, and apoptosis were evaluated in the study, as well as the TLR4/NF-κB/MAPK and IL-10/JAK1/STAT3 signaling pathways for further exploration of the potential mechanism. The results showed that MRS (1) alleviated tissue damage caused by acetic acid, (2) controlled acetic acid-induced inflammation, (3) inhibited acetic acid-caused oxidative stress, (4) reduced colonic cell apoptosis due to acetic acid, (5) suppressed the TLR-4/NF-κB/MAPK signaling pathway, and (6) activated IL-10/JAK1/STAT3 anti-inflammatory response to improve the injury induced by acetic acid. We conclude that MRS has a protective effect on acetic acid-induced ulcerative colitis in mice via blocking the TLR4/NF-κB/MAPK signaling pathway and promoting the IL-10/JAK1/STAT3-mediated anti-inflammatory response.