Ribonuclease attenuates hepatic ischemia reperfusion induced cognitive impairment through the inhibition of inflammatory cytokines in aged mice

Transcranial near-infrared light promotes remyelination through AKT1/mTOR pathway to ameliorate postoperative neurocognitive disorder in aged mice

Postoperative neurocognitive disorder (PND) is a prevalent complication following surgery and anesthesia, characterized by progressive cognitive decline. The precise etiology of PND remains unknown, and effective targeted therapeutic strategies are lacking. Transcranial near-infrared light (tNIRL) has shown potential benefits for cognitive dysfunction diseases, but its effect on PND remains unclear. Our previous research indicated a close association between demyelination and PND. In other central nervous system (CNS) disorders, tNIRL has been demonstrated to facilitate remyelination in response to demyelination. In this study, we established the PND model in 18-month-old male C57BL/6 mice using isoflurane anesthesia combined with left common carotid artery exposure. Following surgery, PND-aged mice were subjected to daily 2.5-minute tNIRL treatment at 810 nm for three consecutive days. Subsequently, we observed that tNIRL significantly improved cognitive performance and reduced inflammatory cytokine levels in the hippocampus of PND mice. Furthermore, tNIRL increased the expression of oligodendrocyte transcription factor 2 (OLIG2) and myelin basic protein (MBP), promoting remyelination while enhancing synaptic function-associated proteins such as synaptophysin (SYP) and postsynaptic density protein 95 (PSD95). Further investigation revealed that tNIRL may activate the AKT1/mTOR pathway to facilitate remyelination in PND mice. These findings indicate that tNIRL is a novel non-invasive therapeutic approach for treating PND.

Circadian Alterations in Brain Metabolism Linked to Cognitive Deficits During Hepatic Ischemia-Reperfusion Injury Using [1H-13C]-NMR Metabolomics

Background: Hepatic ischemia-reperfusion injury (HIRI) is known to affect cognitive functions, with particular concern for its impact on brain metabolic dynamics. Circadian rhythms, as a crucial mechanism for internal time regulation within organisms, significantly influence metabolic processes in the brain. This study aims to explore how HIRI affects hippocampal metabolism and its circadian rhythm differences in mice, and to analyze how these changes are associated with cognitive impairments. Methods: A C57BL/6 male mouse model was used, simulating HIRI through hepatic ischemia-reperfusion surgery, with a sham operation conducted for the control group. Cognitive functions were evaluated using open field tests, Y-maze tests, and novel object recognition tests. Magnetic resonance spectroscopic imaging (MRSI) technology, combined with intravenous injection of [2-13C]-acetate and [1-13C]-glucose, was utilized to analyze metabolic changes in the hippocampus of HIRI mice at different circadian time points (Zeitgeber Time ZT0, 8:00 and ZT12, 20:00). Circadian rhythms regulate behavioral, physiological, and metabolic rhythms through transcriptional feedback loops, with ZT0 at dawn (lights on) and ZT12 at dusk (lights off). Results: HIRI mice exhibited significant cognitive impairments in behavioral tests, particularly in spatial memory and learning abilities. MRSI analysis revealed significant circadian rhythm differences in the concentration of metabolites in the hippocampus, with the enrichment concentrations of lactate, alanine, glutamate, and taurine showing different trends at ZT0 compared to ZT12, highlighting the important influence of circadian rhythms on metabolic dysregulation induced by HIRI. Conclusions: This study highlights the significant impact of HIRI on brain metabolic dynamics in mice, especially in the hippocampal area, and for the first time reveals the differences in these effects within circadian rhythms. These findings not only emphasize the association between HIRI-induced cognitive impairments and changes in brain metabolism but also point out the crucial role of circadian rhythms in this process, offering new metabolic targets and timing considerations for therapeutic strategies against HIRI-related cognitive disorders.

Responsive Multi-Arm PEG-Modified COF Nanocomposites: Dynamic Photothermal, pH/ROS Dual-Responsive, Targeted Carriers for Rheumatoid Arthritis Treatment

Rheumatoid arthritis (RA) is a chronic immune disease characterized by the infiltration of immune cells and the proliferation of fibroblast-like synoviocytes (FLS) at the joint site, leading to inflammation and joint destruction. However, the available treatment options targeting both inflammatory and proliferative FLS are limited. Herein, this work presents three covalent organic frameworks (COFs) photothermal composite systems modified with multi-armed polyethylene glycols (PEG) for the treatment of RA. These systems exhibit a dual response under low pH and high reactive oxygen species (ROS) conditions at the site of inflammation, with a specific focus on delivering the protein drug ribonuclease A (RNase A). Notably, molecular docking studies reveal the interaction between RNase A and NF-κB p65 protein, and Western blotting confirm its inhibitory effect on NF-κB activity. In vitro and in vivo experiments verify the significant reduction in joint swelling and deformities in adjuvant-induced arthritis (AIA) rats after treatment with RNase A delivered by multi-armed PEG-modified COF ligands, restoring joint morphology to normal. These findings underscore the promising therapeutic potential of COFs for the treatment of RA, highlighting their unique capabilities in addressing both inflammatory and proliferative aspects of the disease and expanding the scope of biomedical applications for COFs.

Nucleic acid liquid biopsies in cardiovascular disease: Cell-free RNA liquid biopsies in cardiovascular disease

Cardiovascular diseases (CVD) and their complications continue to be the leading cause of mortality globally. With recent advancements in molecular analytics, individualized treatments are gradually applied to the diagnosis and treatment of CVD. In the field of diagnostics, liquid biopsy combined with modern analytical technologies is the most popular natural source to identify disease biomarkers, as has been successfully demonstrated in the cancer field. While it is not easy to obtain any diseased tissue for different types of CVD such as atherosclerosis, deep vein thrombosis or stroke, liquid biopsies provide a simple and non-invasive alternative to surgical tissue specimens to obtain dynamic molecular information reflecting disease states. The release of cell-free ribonucleic acids (cfRNA) from stressed/damaged/dying and/or necrotic cells is a common physiological phenomenon. CfRNAs are a heterogeneous population of various types of extracellular RNA found in body fluids (blood, urine, saliva, cerebrospinal fluid) or in association with vascular/atherosclerotic tissue, offering insights into disease pathology on a diagnostic front. In particular, cf-ribosomal RNA has been shown to act as a damaging molecule in several cardio-vascular disease conditions. Moreover, such pathophysiological functions of cfRNA in CVD have been successfully antagonized by the administration of RNases. In this review, we discuss the origin, structure, types, and potential utilization of cfRNA in the diagnosis of CVD. Together with the analysis of established CVD biomarkers, the profiling of cfRNA in body fluids may thereby provide a promising approach for early disease detection and monitoring.

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.

The role of lncRNAs related ceRNA regulatory network in multiple hippocampal pathological processes during the development of perioperative neurocognitive disorders

Background

Perioperative neurocognitive disorders (PND) refer to neurocognitive abnormalities during perioperative period, which are a great challenge for elderly patients and associated with increased morbidity and mortality. Our studies showed that long non-coding RNAs (lncRNAs) regulate mitochondrial function and aging-related pathologies in the aged hippocampus after anesthesia, and lncRNAs are associated with multiple neurodegenerations. However, the regulatory role of lncRNAs in PND-related pathological processes remains unclear.

Methods

A total of 18-month mice were assigned to control and surgery (PND) groups, mice in PND group received sevoflurane anesthesia and laparotomy. Cognitive function was assessed with fear conditioning test. Hippocampal RNAs were isolated for sequencing, lncRNA and microRNA libraries were constructed, mRNAs were identified, Gene Ontology (GO) analysis were performed, and lncRNA-microRNA-mRNA networks were established. qPCR was performed for gene expression verification.

Results

A total of 312 differentially expressed (DE) lncRNAs, 340 DE-Transcripts of Uncertain Coding Potential (TUCPs), and 2,003 DEmRNAs were identified in the hippocampus between groups. The lncRNA-microRNA-mRNA competing endogenous RNA (ceRNA) network was constructed with 29 DElncRNAs, 90 microRNAs, 493 DEmRNAs, 148 lncRNA-microRNA interaction pairs, 794 microRNA-mRNA interaction pairs, and 110 lncRNA-mRNA co-expression pairs. 795 GO terms were obtained. Based on the frequencies of involved pathological processes, BP terms were divided into eight categories: neurological system alternation, neuronal development, metabolism alternation, immunity and neuroinflammation, apoptosis and autophagy, cellular communication, molecular modification, and behavior changes. LncRNA-microRNA-mRNA ceRNA networks in these pathological categories were constructed, and involved pathways and targeted genes were revealed. The top relevant lncRNAs in these ceRNA networks included RP23-65G6.4, RP24-396L14.1, RP23-251I16.2, XLOC_113622, RP24-496E14.1, etc., and the top relevant mRNAs in these ceRNA networks included Dlg4 (synaptic function), Avp (lipophagy), Islr2 (synaptic function), Hcrt (regulation of awake behavior), Tnc (neurotransmitter uptake).

Conclusion

In summary, we have constructed the lncRNA-associated ceRNA network during PND development in mice, explored the role of lncRNAs in multiple pathological processes in the mouse hippocampus, and provided insights into the potential mechanisms and therapeutic gene targets for PND.

Treatment with RNase alleviates brain injury but not neuroinflammation in neonatal hypoxia/ischemia

There is a need for new treatments to reduce brain injuries derived from neonatal hypoxia/ischemia. The only viable option used in the clinic today in infants born at term is therapeutic hypothermia, which has a limited efficacy. Treatments with exogenous RNase have shown great promise in a range of different adult animal models including stroke, ischemia/reperfusion injury, or experimental heart transplantation, often by conferring vascular protective and anti-inflammatory effects. However, any neuroprotective function of RNase treatment in the neonate remains unknown. Using a well-established model of neonatal hypoxic/ischemic brain injury, we evaluated the influence of RNase treatment on RNase activity, gray and white matter tissue loss, blood-brain barrier function, as well as levels and expression of inflammatory cytokines in the brain up to 6 h after the injury using multiplex immunoassay and RT-PCR. Intraperitoneal treatment with RNase increased RNase activity in both plasma and cerebropinal fluids. The RNase treatment resulted in a reduction of brain tissue loss but did not affect the blood-brain barrier function and had only a minor modulatory effect on the inflammatory response. It is concluded that RNase treatment may be promising as a neuroprotective regimen, whereas the mechanistic effects of this treatment appear to be different in the neonate compared to the adult and need further investigation.

Gut microbiota regulates circadian oscillation in hepatic ischemia-reperfusion injury-induced cognitive impairment by interfering with hippocampal lipid metabolism in mice

BACKGROUND

Hepatic ischemia-reperfusion injury (HIRI) is a common complication of liver surgery, which can lead to extrahepatic metabolic disorders, such as cognitive impairment. Recent observations have emphasized the critical effects of gut microbial metabolites in regulating the development of liver injury. Herein, we investigated the potential contribution of gut microbiota to HIRI-related cognitive impairment.

METHODS

HIRI murine models were established by ischemia-reperfusion surgery in the morning (ZT0, 08:00) and evening (ZT12, 20:00), respectively. Antibiotic-induced pseudo-germ-free mice were gavaged with fecal bacteria of the HIRI models. Behavioral test was used to assess cognitive function. 16S rRNA gene sequencing and metabolomics were used for microbial and hippocampal analysis.

RESULTS

Our results established that cognitive impairment caused by HIRI underwent diurnal oscillations; HIRI mice performed poorly on the Y-maze test and the novel object preference test when surgery occurred in the evening compared with the morning. In addition, fecal microbiota transplantation (FMT) from the ZT12-HIRI was demonstrated to induce cognitive impairment behavior. The specific composition and metabolites of gut microbiota were analyzed between the ZT0-HIRI and ZT12-HIRI, and bioinformatic analysis showed that the differential fecal metabolites were significantly enriched in lipid metabolism pathways. After FMT, the hippocampal lipid metabolome between the P-ZT0-HIRI and P-ZT12-HIRI groups was analyzed to reveal a series of lipid molecules with significant differences.

CONCLUSIONS

Our findings indicate that gut microbiota are involved in circadian differences of HIRI-related cognitive impairment by affecting hippocampal lipid metabolism.

The weight-adjusted-waist index and cognitive impairment among U.S. older adults: a population-based study

Objectives

Multiple research projects have provided evidence of the correlation between obesity and cognitive impairment. WWI, a novel metric for assessing obesity, has the potential to provide a more precise assessment of muscle and fat mass. This research aimed to investigate the association between WWI and cognitive functioning among elderly individuals residing in the United States.

Methods

This study utilized data from the National Health and Nutrition Examination Survey (NHANES) conducted between 2011 and 2014. Weighted multiple linear regression models, smoothed fitted curves, and generalized weighted models were employed to examine the associations between WWI and cognitive function in linear and nonlinear contexts.

Results

The study included a cohort of 2,764 adult volunteers aged 60 years and older, all with complete data. Upon controlling for all potential confounding variables, our analysis revealed statistically significant negative associations between WWI and the Digit Symbol Substitution Test (DSST) score. Specifically, for each 1-unit increase in WWI, there was a corresponding loss of 3.57 points in the DSST score [-3.57 (-4.31, -2.82)]. The negative correlations between WWI with CERAD total word recall [-0.63 (-0.85, -0.40)], CERAD delayed recall [-0.19 (-0.30, -0.07)], and AFT [-0.65 (-0.94, -0.37)] were significant only in partially adjusted models.

Conclusion

Higher WWI was associated with poorer cognitive function.

Extracellular RNAs/TLR3 signaling contributes to acute intestinal injury induced by intestinal ischemia reperfusion in mice

Toll-like receptor 3 (TLR3), one pattern recognition receptor activated by viral and endogenous RNA, has been recently reported to regulate ischemia/reperfusion (I/R) injury in various organs. However, the role of TLR3 in the development of intestinal I/R injury remains unclear. The aim of this study is to evaluate the effects of extracellular RNAs/TLR3 signaling in intestinal I/R injury. An intestinal I/R injury model was established with superior mesenteric artery occlusion both in wild-type and TLR3 knockout (KO, ^-/-) mice, and MODE-K cells were subjected to hypoxia/reoxygenation (H/R) to mimic the I/R model in vivo. Extracellular RNAs (exRNAs), especially double-stranded RNAs (dsRNAs) co-localized with TLR3, were significantly increased both in vitro and in vivo. Compared with wild-type mice, TLR3 knockout obviously attenuated intestinal I/R injury. Both TLR3/dsRNA complex inhibitor and TLR3 siRNA administration reduced TLR3 expressions and subsequently inhibited intestinal inflammatory cytokine production and apoptosis. In conclusion, exRNAs/TLR3 signaling is a key mechanism that regulates intestinal I/R injury in adult mice, and the TLR3/dsRNA complex inhibitor can be an effective approach for attenuating intestinal I/R-induced inflammatory response and apoptosis.

Functions and cellular signaling by ribosomal extracellular RNA (rexRNA): Facts and hypotheses on a non-typical DAMP

Upon microbial infections with the subsequent host response of innate immunity, a variety of fragmented RNA- and DNA-based "Pathogen-associated molecular patterns" (PAMPs) are recognized mainly by endosomal or cytoplasmic host cell "Pattern recognition receptors" (PRRs), particularly "Toll-like receptors" (TLRs). Concomitantly, various self-extracellular RNA species (exRNAs) are present in extracellular body fluids where they contribute to diverse physiological and homeostatic processes. In principle, such exRNAs, including the most abundant one, ribosomal exRNA (rexRNA), are designated as "Danger-associated molecular patterns" (DAMPs) and are prevented by e.g. natural modifications from uncontrolled signaling via TLRs to avoid hyper-inflammatory responses or autoimmunity. Upon cellular stress or tissue damage/necrosis, the levels and composition of released self-exRNA species, either in free form, in complex with proteins or in association with extracellular vesicles (EVs), can change considerably. Among the self-exRNAs, rexRNA is considered as a non-typical DAMP, since it may induce inflammatory responses by cell membrane receptors, both in the absence or presence of PAMPs. Yet, its mode of receptor activation to mount inflammatory responses remains obscure. RexRNA also serves as a universal damaging factor in cardiovascular and other diseases independent of PRRs. In general, RNase1 provides a profound antagonist in these pathologies and in rexRNA-mediated inflammatory cell responses. Based on the extrapolation of the here described aspects of rexRNA-biology, further activities of this molecular entity are hypothesized that may stimulate additional research in this area.

Effect of dexmedetomidine on postoperative systemic inflammation and recovery in patients undergoing digest tract cancer surgery: A meta-analysis of randomized controlled trials

Perioperative immune function, postoperative cognitive function and prognosis are momentous issues for patients undergoing digestive tract cancer surgery. Studies have investigated the efficacy of dexmedetomidine (DEX) administration on these issues, but the results are inconsistent. Therefore, this meta-analysis aimed to summarize all the existing evidence and draw a conclusion more accurately on these associations. Trials were located through electronic searches of the PubMed, Embase, the Cochrane Library and Web of Science databases sources (from the establishment date of databases to April 2022). Bibliographies of the retrieved articles were checked. A total of 17 RCTs involving 1619 patients were included. The results showed that DEX decreased the level of C-reactive protein (SMD = -4.26, 95%CI: -6.16, -2.36), TNF-α (SMD = -4.22, 95%CI: -5.91, -2.54) and IL-6 (SMD = -2.71, 95%CI: -4.46, -0.97), and increased the level of IL-10 (SMD = 1.74, 95%CI: 0.25, 3.24). DEX also increased CD4+ T cells (SMD = 0.55, 95%CI: 0.29, 0.82) and CD4+/CD8+ ratio (SMD = 0.62, 95%CI: 0.24, 1.01). Thus, DEX was associated with alleviation of postoperative systemic inflammatory response and immune dysfunction. Furthermore, DEX increased mini-mental state examination scores at 12h (SMD = 1.10, 95%CI: 0.74,1.45), 24h (SMD = 0.85, 95%CI: 0.59, 1.11), 48h (SMD = 0.89, 95%CI: 0.50, 1.28) and 72h (SMD = 0.75, 95%CI: 0.38, 1.11) after surgery. DEX decreased the occurrence of postoperative cognitive dysfunction (POCD) at 24h (OR = 0.22, 95%CI: 0.11, 0.46) and 72h (OR = 0.39, 95%CI: 0.22, 0.68) after surgery. DEX decreased first flatus time (SMD = -1.55, 95%CI: -2.82, -0.27) and hospital stay (SMD = -1.23, 95%CI: -1.88, -0.59). Therefore, based on perioperative immune dysfunction alleviation, DEX attenuated POCD and potential neuroinflammation, improved postoperative recovery and clinical prognosis of patients undergoing digest tract cancer surgery. Further studies are necessary to elucidate the clinical application of DEX from an immunological perspective.

Effects of different types of non-cardiac surgical trauma on hippocampus-dependent memory and neuroinflammation

Background

Older individuals have been reported to suffer from cognitive disorders after surgery. Various types of surgical trauma have been used to establish postoperative cognitive dysfunction (POCD) animal models in preclinical studies. However, few comparative analyses of these animal models were conducted.

Methods

Tibial surgery, abdominal surgery, and extended abdominal surgery were performed on aged ICR mice to establish POCD models. Behavioral tests included open field, novel object recognition, fear conditioning, and Morris water maze tests. The Z-score methodology was adopted to obtain a comprehensive and integrated memory performance profile. The changes in hippocampal neuroinflammation were analyzed by ELISA, PCR, and immunofluorescence.

Results

In this study, we found that each type of non-cardiac surgical trauma has a different effects on locomotor activity. Tibial and extended abdominal surgeries led to more significant cognitive impairment than abdominal surgery. Inflammatory cytokines peaked on postoperative day 1 and decreased to control levels on days 3 and 7. Hippocampal neuroinflammation indicators between the three surgery types on postoperative day 1 had no statistical differences.

Conclusion

Overall, the type and intensity of non-cardiac surgical trauma can affect cognitive behavioral outcomes and central inflammation. The shortcomings and emerging issues of POCD animal research methods need to be further studied and solved.

Dexmedetomidine Ameliorated Cognitive Dysfunction Induced by Intestinal Ischemia Reperfusion in Mice with Possible Relation to the Anti-inflammatory Effect Through the Locus Coeruleus Norepinephrine System

Cognitive impairment is a common central nervous system complication that occurs following surgery or organs damage outside the nervous system. Neuroinflammation plays a key role in the molecular mechanisms of cognitive impairment. Dexmedetomidine alleviates neuroinflammation and reduces cognitive dysfunction incidence; however, the mechanism by which dexmedetomidine alleviates cognitive dysfunction remains unclear. This study evaluated the effect of dexmedetomidine on attenuation of early cognitive impairment induced by intestinal ischemia–reperfusion in mice and examined whether the locus coeruleus norepinephrine (LCNE) system participates in the anti-inflammatory effect of dexmedetomidine. The superior mesenteric artery was clamped for 45 min to induce intestinal ischemia reperfusion injury. Dexmedetomidine alone or combined with DSP-4, a selective locus coeruleus noradrenergic neurotoxin, was used for pretreatment. Postoperative cognition was assessed using the Morris water maze. Serum and hippocampal levels of IL-1β, TNF-α, norepinephrine (NE), and malondialdehyde (MDA) were assessed by enzyme-linked immunosorbent assay. Immunofluorescence, immunohistochemistry, and hematoxylin and eosin staining were used to evaluate the expression of tyrosine hydroxylase (TH) in the locus coeruleus, hippocampal microglia, and intestinal injury. Pretreatment with dexmedetomidine alleviated intestinal injury and decreased the serum and hippocampal levels of NE, IL-1β, TNF-α, and MDA at 24 h after intestinal ischemia reperfusion, decreased TH-positive neurons in the locus coeruleus, and ameliorated cognitive impairment. Similarly, DSP-4 pre-treatment alleviated neuroinflammation and improved cognitive function. Furthermore, α2-adrenergic receptor antagonist atipamezole or yohimbine administration diminished the neuroprotective effects and improved cognitive function with dexmedetomidine. Therefore, dexmedetomidine attenuated early cognitive dysfunction induced by intestinal ischemia–reperfusion injury in mice, which may be related to its anti-inflammatory effects through the LCNE system.

Targeting AGEs-RAGE pathway inhibits inflammation and presents neuroprotective effect against hepatic ischemia-reperfusion induced hippocampus damage

BACKGROUND

The present study aimed to investigate the role of AGEs-RAGE signaling and its potential as a treatment target in hepatic ischemia-reperfusion (HIR)-induced hippocampus damage.

METHODS

HIR operation was conducted in mice, followed by collection of hippocampus tissue at 1 day, 3 days and 7 days. Additionally, low dose, moderate dose and high dose FPS-ZM1 (RAGE inhibitor) was intraperitoneally injected into HIR mice. Besides, sham operation was conduced in mice which served as control.

RESULTS

HIR increased the hippocampal damage and enhanced its neuron apoptosis within 3 days, which recovered to some extent from day 3 to day 7 post operation. Meanwhile, the expressions of AGEs, RAGE, the downstream proteins in AGEs-RAGE signaling pathway (including PI3K, pAKT, pNKκB p65 and pERK1/2), and the inflammatory cytokines (including IL-1β, IL-6, TNF-α) were increased within 3 days, but were reduced from day 3 to day 7 post operation by HIR. Notably, moderate and high dose of FPS-ZM1 attenuated hippocampal damage, inhibited its neuron apoptosis, inactivated AGEs-RAGE signaling, and suppressed the expressions of inflammatory cytokines (including IL-1β, IL-6, TNF-α); but lose dose of FPS-ZM1 failed to achieve these effects.

CONCLUSIONS

Targeting AGEs-RAGE pathway inhibits inflammation and presents neuroprotective effect against HIR-induced hippocampus damage.

Single-Cell Sequencing Reveals an Intrinsic Heterogeneity of the Preovulatory Follicular Microenvironment

The follicular microenvironment, including intra-follicular granulosa cells (GCs), is responsible for oocyte maturation and subsequent ovulation. However, the functions of GCs and cellular components of the follicular microenvironment in preovulatory follicles have not been extensively explored. Here, we surveyed the single-cell transcriptome of the follicular microenvironment around MII oocytes in six human preovulatory follicles in in vitro fertilization. There were six different cell types in the preovulatory follicles, including GCs and various immune cells. In GCs, we identified nine different functional clusters with different functional transcriptomic profiles, including specific clusters involved in inflammatory responses and adhesive function. Follicular macrophages are involved in immune responses, extracellular matrix remoulding and assist GCs in promoting the oocyte meiotic resumption. Interestingly, we observed that the specific terminal state subcluster of GCs with high levels of adhesive-related molecules should result in macrophage recruitment and residence, further contributing to an obvious heterogeneity of the immune cell proportion in preovulatory follicles from different patients. Our results provide a comprehensive understanding of the transcriptomic landscape of the preovulatory follicular microenvironment at the single-cell level. It provides valuable insights into understanding the regulation of the oocyte maturation and ovulation process, offering potential clues for the diagnosis and treatment of oocyte-maturation-related and ovulation-related diseases.

Hepatic Ischemia-Reperfusion Impairs Blood-Brain Barrier Partly Due to Release of Arginase From Injured Liver

Aim: Hepatic ischemia-reperfusion (HIR) induces remote organs injury, including the brain. The homeostasis of the brain is maintained by the blood-brain barrier (BBB); thus, we aimed to investigate whether HIR impaired BBB and attempted to elucidate its underlying mechanism.

Methods: Cell viability of human cerebral microvascular endothelial cells (hCMEC/D3) was measured following 24 h incubation with a serum of HIR rat undergoing 1 h ischemia and 4 h reperfusion, liver homogenate, or lysate of primary hepatocytes of the rat. The liver homogenate was precipitated using (NH₄)₂SO₄ followed by separation on three columns and electrophoresis to identify the toxic molecule. Cell activity, apoptosis, proliferation, cell cycle, and expressions of proteins related to cell cycle were measured in hCMEC/D3 cells incubated with identified toxic molecules. HIR rats undergoing 1 h ischemia and 24 h reperfusion were developed to determine the release of an identified toxic molecule. BBB function was indexed as permeability to fluorescein and brain water. Endothelial cell proliferation and expressions of proteins related to the cell cycle in cerebral microvessels were measured by immunofluorescence and western blot.

Results: Toxic molecule to BBB in the liver was identified to be arginase. Arginase inhibitor nor-NOHA efficiently attenuated hCMEC/D3 damage caused by liver homogenate and serum of HIR rats. Both arginase and serum of HIR rats significantly lowered arginine (Arg) in the culture medium. Arg addition efficiently attenuated the impairment of hCMEC/D3 caused by arginase or Arg deficiency, demonstrating that arginase impaired hCMEC/D3 via depriving Arg. Both arginase and Arg deficiency damaged hCMEC/D3 cells by inhibiting cell proliferation, retarding the cell cycle to G1 phase, and downregulating expressions of cyclin A, cyclin D, CDK2, and CDK4. HIR notably increased plasma arginase activity and lowered Arg level, increased the BBB permeability accompanied with enhanced brain water, and decreased the proliferative cells (marked by Ki67) in cerebral microvessels (marked by CD31) and protein expressions of cyclin A, cyclin D, CDK2 and CDK4 in isolated brain microvessels. Oral supplement of Arg remarkably attenuated these HIR-induced alterations.

Conclusion: HIR leads to substantial release of arginase from the injured liver and then deprives systemic Arg. The Arg deficiency further impairs BBB via inhibiting the proliferation of brain microvascular endothelial cells by cell cycle arrest.

Carbon Monoxide-Releasing Molecule-3 Alleviates Kupffer Cell Pyroptosis Induced by Hemorrhagic Shock and Resuscitation via sGC-cGMP Signal Pathway

Following hepatic ischemia-reperfusion injury, Kupffer cells could be activated by inflammatory factors released from damaged hepatocytes. Carbon monoxide (CO)-releasing molecule (CORM)-3, a water-soluble transition metal carbonyl, exhibits excellent anti-inflammatory and anti-pyroptosis properties. We investigated whether CORM-3 attenuated hemorrhagic shock and resuscitation (HSR)-induced pyroptosis of Kupffer cells through the soluble guanylate-cyclase (sGC)-cyclic guanosine monophosphate (cGMP) signal pathway. NS2028 (10 mg/kg), a blocker of sGC, was administrated at the onset of hemorrhage, but CORM-3 (4 mg/kg) was infused after resuscitation via femoral vein. Serum alanine aminotransferase (ALT), aspartate aminotransferase (AST) levels, tumor necrosis Factor-α (TNF-α), and interleukin-1β (IL-1β) were measured at 3, 6, 12, and 24 h after HSR, respectively. Six hours post-HSR, liver injury, pyroptosis of Kupffer cells, and expressions in total caspase-1, cleaved caspase-1, gasdermin D (GSDMD) N-terminal fragment, IL-1β, and IL-18 were measured by hematoxylin-eosin (H&E), immunofluorescence and western blot assays, respectively (Fig. 1). The rats exposed to HSR exhibited significant upregulated levels of serum ALT, AST, TNF-α, and IL-1β, elevated liver injury score, increased pyroptosis of Kupffer cells, and accumulated expressions of pyroptosis-associated protein including cleaved caspase-1, GSDMD N-terminal fragment, IL-1β, and IL-18 than sham-treated rats. However, CORM-3 administration markedly reduced liver injury and pyroptosis of Kupffer cells, whereas these protective effects could be partially blocked by NS2028. CORM-3 can mitigate pyroptosis of Kupffer cells in a blood loss and re-infusion model of rats via sGC-cGMP signal pathway.

Role of Atypical Chemokines and Chemokine Receptors Pathways in the Pathogenesis of COPD

Chronic obstructive pulmonary disease (COPD) represents a heightened inflammatory response in the lung generally resulting from tobacco smoking-induced recruitment and activation of inflammatory cells and/or activation of lower airway structural cells. Several mediators can modulate activation and recruitment of these cells, particularly those belonging to the chemokines (conventional and atypical) family. There is emerging evidence for complex roles of atypical chemokines and their receptors (such as high mobility group box 1 (HMGB1), antimicrobial peptides, receptor for advanced glycosylation end products (RAGE) or toll-like receptors (TLRs)) in the pathogenesis of COPD, both in the stable disease and during exacerbations. Modulators of these pathways represent potential novel therapies for COPD and many are now in preclinical development. Inhibition of only a single atypical chemokine or receptor may not block inflammatory processes because there is redundancy in this network. However, there are many animal studies that encourage studies for modulating the atypical chemokine network in COPD. Thus, few pharmaceutical companies maintain a significant interest in developing agents that target these molecules as potential antiinflammatory drugs. Antibody-based (biological) and small molecule drug (SMD)-based therapies targeting atypical chemokines and/or their receptors are mostly at the preclinical stage and their progression to clinical trials is eagerly awaited. These agents will most likely enhance our knowledge about the role of atypical chemokines in COPD pathophysiology and thereby improve COPD management.

The Role of Nucleases and Nucleic Acid Editing Enzymes in the Regulation of Self-Nucleic Acid Sensing

Detection of microbial nucleic acids by the innate immune system is mediated by numerous intracellular nucleic acids sensors. Upon the detection of nucleic acids these sensors induce the production of inflammatory cytokines, and thus play a crucial role in the activation of anti-microbial immunity. In addition to microbial genetic material, nucleic acid sensors can also recognize self-nucleic acids exposed extracellularly during turn-over of cells, inefficient efferocytosis, or intracellularly upon mislocalization. Safeguard mechanisms have evolved to dispose of such self-nucleic acids to impede the development of autoinflammatory and autoimmune responses. These safeguard mechanisms involve nucleases that are either specific to DNA (DNases) or RNA (RNases) as well as nucleic acid editing enzymes, whose biochemical properties, expression profiles, functions and mechanisms of action will be detailed in this review. Fully elucidating the role of these enzymes in degrading and/or processing of self-nucleic acids to thwart their immunostimulatory potential is of utmost importance to develop novel therapeutic strategies for patients affected by inflammatory and autoimmune diseases.

Blocking the Mineralocorticoid Receptor Improves Cognitive Impairment after Anesthesia/Splenectomy in Rats

Recent mounting studies showed that neuroinflammation caused by surgery or anesthesia is closely related to postoperative cognitive dysfunction (POCD). This study investigated the effect of mineralocorticoid receptor (MR) on neuroinflammation and POCD. To detect the MR effect in an animal model, we randomly divided rats into control, anesthesia, and surgery groups. To determine whether the MR-specific blocker eplerenone (EPL) could improve cognitive dysfunction, we assigned other animals into the control, surgery and EPL treatment, and surgery groups. Cognitive function was detected using the Morris water maze. Serum cytokine levels were measured by ELISA, and the histopathological changes of hippocampal neurons were identified by hematoxylin/eosin and Nissl staining. Our research confirmed that anesthesia and surgical stimulation could lead to IL-1β, IL-6, and TNF-α activation and hippocampal neuronal degeneration and pathological damage. MR was upregulated in the hippocampus under cognitive impairment condition. Additionally, EPL could alleviate inflammatory activation and neuronal damage by exerting neuroprotective effects. The preclinical model of sevoflurane anesthesia/splenectomy implied that MR expression is upregulated by regulating the neuroinflammation in the brain under POCD condition. Manipulating the MR expression by EPL could improve the inflammation activation and neuronal damage.

Extracellular RNA as a Versatile DAMP and Alarm Signal That Influences Leukocyte Recruitment in Inflammation and Infection

Upon vascular injury, tissue damage, ischemia, or microbial infection, intracellular material such as nucleic acids and histones is liberated and comes into contact with the vessel wall and circulating blood cells. Such "Danger-associated molecular patterns" (DAMPs) may thus have an enduring influence on the inflammatory defense process that involves leukocyte recruitment and wound healing reactions. While different species of extracellular RNA (exRNA), including microRNAs and long non-coding RNAs, have been implicated to influence inflammatory processes at different levels, recent in vitro and in vivo work has demonstrated a major impact of ribosomal exRNA as a prominent DAMP on various steps of leukocyte recruitment within the innate immune response. This includes the induction of vascular hyper-permeability and vasogenic edema by exRNA via the activation of the "vascular endothelial growth factor" (VEGF) receptor-2 system, as well as the recruitment of leukocytes to the inflamed endothelium, the M1-type polarization of inflammatory macrophages, or the role of exRNA as a pro-thrombotic cofactor to promote thrombosis. Beyond sterile inflammation, exRNA also augments the docking of bacteria to host cells and the subsequent microbial invasion. Moreover, upon vessel occlusion and ischemia, the shear stress-induced release of exRNA initiates arteriogenesis (i.e., formation of natural vessel bypasses) in a multistep process that resembles leukocyte recruitment. Although exRNA can be counteracted for by natural circulating RNase1, under the conditions mentioned, only the administration of exogenous, thermostable, non-toxic RNase1 provides an effective and safe therapeutic regimen for treating the damaging activities of exRNA. It remains to be investigated whether exRNA may also influence viral infections (including COVID-19), e.g., by supporting the interaction of host cells with viral particles and their subsequent invasion. In fact, as a consequence of the viral infection cycle, massive amounts of exRNA are liberated, which can provoke further tissue damage and enhance virus dissemination. Whether the application of RNase1 in this scenario may help to limit the extent of viral infections like COVID-19 and impact on leukocyte recruitment and emigration steps in immune defense in order to limit the extent of associated cardiovascular diseases remains to be studied.

Endothelial Ribonuclease 1 in Cardiovascular and Systemic Inflammation

The vascular endothelial cell layer forms the inner lining of all blood vessels to maintain proper functioning of the vascular system. However, dysfunction of the endothelium depicts a major issue in context of vascular pathologies, such as atherosclerosis or thrombosis that cause several million deaths per year worldwide. In recent years, the endothelial extracellular endonuclease Ribonuclease 1 (RNase1) was described as a key player in regulation of vascular homeostasis by protecting endothelial cells from detrimental effects of the damage-associated molecular pattern extracellular RNA upon acute inflammation. Despite this protective function, massive dysregulation of RNase1 was observed during prolonged endothelial cell inflammation resulting in progression of several vascular diseases. For the first time, this review article outlines the current knowledge on endothelial RNase1 and its role in function and dysfunction of the endothelium, thereby focusing on the intensive research from recent years: Uncovering the underlying mechanisms of RNase1 function and regulation in response to acute as well as long-term inflammation, the role of RNase1 in context of vascular, inflammatory and infectious diseases and the potential to develop novel therapeutic options to treat these pathologies against the background of RNase1 function in endothelial cells.

Identification of the Potential Key Circular RNAs in Elderly Patients With Postoperative Cognitive Dysfunction

Background

Postoperative cognitive dysfunction (POCD) is one of the severe complications after surgery, inducing low life quality and high mortality, especially in elderly patients. However, the underlying molecular mechanism of POCD remains largely unknown, and the ideal biomarker for clinical diagnosis and prognosis is lacking. Circular RNAs (circRNAs), as a unique class of non-coding RNAs, were characterized by its stability and conservativeness, serving as novel biomarkers in various diseases. Nevertheless, the role of circRNAs in the occurrence of POCD remains elusive.

Methods

To investigate the differentially expressed circRNAs in the serum of POCD patients and its potential role in the development of POCD, we performed a circRNA microarray to screen the differentially expressed circRNAs in the serum samples from three patients of the POCD group and three paired patients of the non-POCD group. Subsequently, quantitative real-time polymerase chain reaction analysis (qRT-PCR) was utilized to verify the microarray data with the serum samples from 10 paired patients. Cytoscape software was used to construct the circRNA–miRNA–mRNA network for circRNAs with different expression levels as well as the target genes. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses showed the biological functions of the differentially expressed circRNAs target genes.

Results

In total, we have analyzed 10,198 circRNAs through the microarray. Compared with the non-POCD patient group, there were 210 differentially expressed circRNAs with 133 upregulated and 77 downregulated in the POCD group (≥2-fold differential expression, P ≤ 0.05). The qRT-PCR confirmed 10 circRNAs with different expressed levels, and the results were consistent with the microarray findings. Among them, hsa_circRNA_001145, hsa_circRNA_101138, and hsa_circRNA_061570 had the highest magnitude of change. The GO analysis showed that the differentially expressed circRNAs were associated with the regulation of the developmental process, cell-to-cell adhesion, and nervous system development. The KEGG analysis showed that the target genes of circRNAs were enriched in the MAPK signaling pathway and RAS signaling pathway. According to the targetscan7.1 and mirdbV5 databases, the circRNA–miRNA–mRNA network was constructed, and these results provided a vital landscape of circRNA expression profile in POCD.

Conclusions

Our study provides an essential perspective for the differential expression of circRNAs in POCD patients. Further studies need to be performed to explore their potential therapeutic roles in the development of POCD.

Ribonuclease attenuates retinal ischemia reperfusion injury through inhibition of inflammatory response and apoptosis in mice

The present study was aimed to reveal the function of extracellular RNAs (exRNAs) in retinal ischemia reperfusion (I/R) injury, and evaluate whether RNase administration can effectivelyreduce I/Rinjury. A retinal I/R injury C57BL/6J wild-type mice model was established by elevating intraocular pressure for 1 h. All mice received 3 doses of RNase or the same dose of normal saline at different time points. After 7 days of reperfusion, retinal damage was quantified by counting retinal ganglion cells and measuring retinal layer thickness. The apoptotic retinal cells were detected by the TUNEL experiment, and the expressions of caspase-3, proinflammatory cytokines in retinal tissues, and glial fibrillary acidic protein (GFAP) protein and mRNA were detected to determine the underlying mechanism. It was found that RNase administration (1) reduced the significant loss of retinal morphology caused by I/R injury; (2) down-regulated the expression of NF-κBp65, IL-6 and GFAP relative to the I/R mice; (3) decreased the apoptosis of retinal cells and the levels of caspase-3; (4) attenuated exRNAs levels in retinal tissues on day 7 after retinal I/R. In short, increased exRNAs may contribute to retinal I/R damages in mice, and RNase therapy can effectively attenuate retinal damage by reducing inflammatory response and apoptosis.

Ribonuclease attenuates acute intestinal injury induced by intestinal ischemia reperfusion in mice

Ribonuclease (RNase) reportedly exerts organ-protective effects in several pathological conditions, including ischemia reperfusion (I/R), but whether it can exhibit protective effect on intestinal I/R injury and potential mechanisms remain unknown. The present study was aimed to evaluate the effects of RNase on intestinal I/R injury and explore the underlying mechanisms. Thirty-two wild-type C57BL/6J adult male mice were evenly divided into a sham group, a sham + RNase group, an I/R group and an I/R + RNase group. Intestinal I/R was produced by clamping the superior mesenteric artery for 1 h followed by reperfusion for 2 h. All mice were treated with 3 doses of RNase or the same dosage of normal saline at different points. It was found that intestinal I/R caused significant intestinal injury and an increase in levels of extracellular RNAs (exRNAs). Treatment with RNase significantly reduced the inflammatory cytokine production, inhibited intestinal apoptosis and down-regulated the expression of toll like receptor 3 in intestinal tissues. In conclusion, increased exRNAs may contribute to intestinal I/R injury in adult mice, and RNase treatment during perioperative window is effective for attenuating intestinal I/R injury.

Characteristics of Changes in Inflammatory Cytokines as a Function of Hepatic Ischemia-Reperfusion Injury Stage in Mice

Liver ischemia-reperfusion injury (IRI) can severely compromise the prognosis of patients receiving liver surgery. While inflammation contributes to the damage resulting from IRI, only a limited number of inflammation biomarkers have been identified as being associated with the different stages of hepatic IRI. As an approach to identify some of these inflammatory cytokines and the molecular mechanisms involved within different stages of hepatic IRI, we used an advanced antibody array assay to detect multiple proteins. With this technology, we observed specific differences in the content of inflammatory cytokines between ischemic and sham controls, as well as a function of the different reperfusion stages in a hepatic IRI mouse model. For example, while liver tissue content of IL-12p40/p70 was significantly increased in the ischemic stage, it was significantly decreased in the reperfusion stage as compared with that of the sham group. For other inflammatory cytokines, no changes were obtained between the ischemic and reperfusion stages with levels of IL-17, Eotaxin-2, Eotaxin, and sTNF RII all being consistently increased, while those of TIMP-1, TIMP-2, BLC, and MCSF consistently decreased as compared with that of the sham group at all reperfusion stages examined. Results from protein function annotation Gene Ontology and the KEGG pathway revealed that inflammatory cytokines are enriched in a network associated with activation of inflammatory response signaling pathways such as TLR, TNF, and IL-17 when comparing responses of the IR versus sham groups. The identification of cytokines along with their roles at specific stages of IRI may reveal important new biological markers for the diagnosis and prognosis of hepatic IRI.

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.

Exosomes Mediate Hippocampal and Cortical Neuronal Injury Induced by Hepatic Ischemia-Reperfusion Injury through Activating Pyroptosis in Rats

Background

The neuronal injury and cognitive dysfunction after liver transplantation have severe effects on the prognosis and life quality of patients. Accumulating evidence suggests that both exosomes and pyroptosis could participate in hepatic ischemia-reperfusion injury (HIRI) and play key roles in neuronal death. However, the link between exosomes and neuronal pyroptosis in HIRI awaits further investigation.

Methods

After establishing the HIRI rat models, we primarily studied the role of pyroptosis in hippocampal and cortical neuron injury through detecting NOD-like receptor protein 3 (NLRP3), pro-caspase-1, cleaved-caspase-1, apoptosis-associated speck-like protein containing CARD (ASC), gasdermin D (GSDMD), interleukin-1beta (IL-1β), and interleukin-18 (IL-18) expressions with western blotting, immunohistochemical staining, and enzyme-linked immunosorbent assay (ELISA). Then, we intravenously injected normal male rats with exosomes isolated from the sera of HIRI-challenged rats and pretreated rats with MCC950, a specific inhibitor of NLRP3, and carried out the same assay. We also detected the levels of reactive oxygen species (ROS), superoxide dismutase (SOD), and malondialdehyde (MDA) in the hippocampal and cortical tissues.

Results

The results indicated that NLRP3 inflammasome and caspase-1-dependent pyroptosis were activated in the hippocampus and cortex of HIRI rats. Furthermore, serum-derived exosomes from HIRI-challenged rats not only had the ability to cross the blood-brain barrier (BBB) but also had the similar effects on neuronal pyroptosis. Moreover, ROS and MDA productions were induced in the HIRI and exosome-challenged groups. In addition, to some degree, MCC950 could alleviate HIRI-mediated hippocampal and cortical neuronal pyroptosis.

Conclusion

This study experimentally demonstrated that circulating exosomes play a critical role in HIRI-mediated hippocampal and cortical injury through regulating neuronal pyroptosis.

Effect of dexmedetomidine on postoperative cognitive dysfunction and inflammation in patients after general anaesthesia: A PRISMA-compliant systematic review and meta-analysis

BACKGROUND

Neuroprotective effects of dexmedetomidine are reported in preclinical and clinical studies but evidence regarding the postoperative neurocognitive function is still unclear. This study performed a meta-analysis on outcomes of studies which examined neurocognitive performance and inflammatory factors to investigate the effects of dexmedetomidine on postoperative cognitive dysfunction (POCD) and inflammation in patients after general anaesthesia.

METHODS

Literatures were searched in several electronic databases and studies were selected by following precise inclusion criteria. We searched PubMed, EMBASE, the Cochrane Library, China Academic Journals full-text database (CNKI), and Google Scholar to find randomized controlled trials (RCTs) of the influence of dexmedetomidine on POCD and inflammation in patients who had undergone general anaesthesia. Two researchers independently screened the literature, extracted data, and evaluated quality of methodology against inclusion and exclusion criteria. Meta-analyses of pooled ORs of POCD incidences and mean differences in neurocognitive assessment scores and inflammation levels were carried out and subgroup analyses were performed. Stata 12.0 was used to conduct our meta-analysis.

RESULTS

Twenty-six RCTs were included. Compared with controls, perioperative dexmedetomidine treatment significantly reduced the incidence of POCD (pooled ORs = 0.59, 95% confidence interval (CI) 0.45-2.95) and improved Mini-Mental State Examination (MMSE) score (standardized mean difference (SMD) = 1.74, 95% CI 0.43-3.05) on the first postoperative day. Furthermore, perioperative dexmedetomidine treatment significantly decreased IL-6 (SMD = -1.31, 95% CI -1.87-0.75, P < .001) and TNF-α (SMD = -2.14, 95% CI -3.14-1.14, P < .001) compared to saline/comparators treatment. In the stratified analysis by surgical type, age, type of control, and study region, the differences were also significant between dexmedetomidine- and saline-treated patients.

CONCLUSION

Perioperative dexmedetomidine treatment is associated with significantly reduced incidence of POCD and inflammation and better neurocognitive function postoperatively in comparison with both saline controls and comparator anaesthetics.

Functional roles of the human ribonuclease A superfamily in RNA metabolism and membrane receptor biology

The human ribonuclease A (hRNase A) superfamily is comprised of 13 members of secretory RNases, most of which are recognized as catabolic enzymes for their ribonucleolytic activity to degrade ribonucleic acids (RNAs) in the extracellular space, where they play a role in innate host defense and physiological homeostasis. Interestingly, human RNases 9-13, which belong to a non-canonical subgroup of the hRNase A superfamily, are ribonucleolytic activity-deficient proteins with unclear biological functions. Moreover, accumulating evidence indicates that secretory RNases, such as human RNase 5, can be internalized into cells facilitated by membrane receptors like the epidermal growth factor receptor to regulate intracellular RNA species, in particular non-coding RNAs, and signaling pathways by either a ribonucleolytic activity-dependent or -independent manner. In this review, we summarize the classical role of hRNase A superfamily in the metabolism of extracellular and intracellular RNAs and update its non-classical function as a cognate ligand of membrane receptors. We further discuss the biological significance and translational potential of using secretory RNases as predictive biomarkers or therapeutic agents in certain human diseases and the pathological settings for future investigations.

Dephosphorylation by calcineurin regulates translocation of dynamin-related protein 1 to mitochondria in hepatic ischemia reperfusion induced hippocampus injury in young mice

Hepatic ischemia reperfusion (HIR) has been found to induce brain injury and cognitive dysfunction. Dynamin-related protein 1 (Drp1) mediated mitochondrial fission involves oxidative stress, apoptosis and several neurological diseases. In this study, we investigated whether Drp1 translocation to mitochondria was implicated in HIR induced hippocampus injury in young mice, and further detected the role of calcineurin in the regulation of mitochondrial dynamics. 2-week C57BL/6 mice were chosen to make HIR model. Western blot was used to detect mitochondrial dynamics regulating proteins in whole hippocampal tissues and extracted mitochondria. Transmission electron microscopy was used to observe mitochondrial morphology. TUNEL staining and ELISA (serum S100β/NSE concentrations) were used to evaluate neurons apoptosis and brain injury respectively. Drp1 inhibitor Mdivi-1 and calcineurin inhibitor FK506 were utilized to further confirm the role of Drp1 and calcineurin. Results showed that HIR affected mitochondrial dynamics in a fission-dominant manner with translocation of Drp1 to mitochondria in hippocampus of young mice. HIR induced increased expression of calcineurin and dephosphorylation of Drp1 at Ser637 in hippocampus. Treatment with Mdivi-1 and FK506 upregulated the phosphorylation of Drp1, inhibited Drp1 translocation to mitochondria, and alleviated mitochondrial fragmentation after HIR. What's more, Mdivi-1 and FK506 restrained cytochrome c release and cleaved caspase-3 expression, ameliorated hippocampal neurons apoptosis, and decreased serum S100β/NSE concentrations as well. These data suggest that calcineurin mediated Drp1 dephosphorylation and translocation to mitochondria play a crucial role in HIR induced mitochondrial fragmentation and neurons apoptosis in hippocampus.

The Immunomodulatory and Antimicrobial Properties of the Vertebrate Ribonuclease A Superfamily

The Ribonuclease A Superfamily is composed of cationic peptides that are secreted by immune cells and epithelial tissues. Although their physiological roles are unclear, several members of the vertebrate Ribonuclease A Superfamily demonstrate antimicrobial and immune modulation activities. The objective of this review is to provide an overview of the published literature on the Ribonuclease A Superfamily with an emphasis on each peptide’s regulation, antimicrobial properties, and immunomodulatory functions. As additional insights emerge regarding the mechanisms in which these ribonucleases eradicate invading pathogens and modulate immune function, these ribonucleases may have the potential to be developed as a novel class of therapeutics for some human diseases.

Immune Modulation by Human Secreted RNases at the Extracellular Space

The ribonuclease A superfamily is a vertebrate-specific family of proteins that encompasses eight functional members in humans. The proteins are secreted by diverse innate immune cells, from blood cells to epithelial cells and their levels in our body fluids correlate with infection and inflammation processes. Recent studies ascribe a prominent role to secretory RNases in the extracellular space. Extracellular RNases endowed with immuno-modulatory and antimicrobial properties can participate in a wide variety of host defense tasks, from performing cellular housekeeping to maintaining body fluid sterility. Their expression and secretion are induced in response to a variety of injury stimuli. The secreted proteins can target damaged cells and facilitate their removal from the focus of infection or inflammation. Following tissue damage, RNases can participate in clearing RNA from cellular debris or work as signaling molecules to regulate the host response and contribute to tissue remodeling and repair. We provide here an overall perspective on the current knowledge of human RNases’ biological properties and their role in health and disease. The review also includes a brief description of other vertebrate family members and unrelated extracellular RNases that share common mechanisms of action. A better knowledge of RNase mechanism of actions and an understanding of their physiological roles should facilitate the development of novel therapeutics.