CircPTK2-miR-181c-5p-HMGB1: a new regulatory pathway for microglia activation and hippocampal neuronal apoptosis induced by sepsis

Downregulation of miR-181c-5p in Alzheimer's disease weakens the response of microglia to Aβ phagocytosis

Alzheimer's disease (AD) is an age-associated neurodegenerative disease. Recently, studies have demonstrated the potential involvement of microRNA-181c-5p (miR-181c-5p) in AD. However, the mechanism through which miR-181c-5p is responsible for the onset and progression of this disease remains unclear, and our study aimed to explore this problem. Differential expression analysis of the AD dataset was performed to identify dysregulated genes. Based on hypergeometric analysis, AD differential the upstream regulation genes miR-181c-5p was found. We constructed a model where SH-SY5Y and BV2 cells were exposed to Aβ1-42 to simulate AD. Levels of tumor necrosis factor-alpha, interleukin-6, and IL-1β were determined using enzyme-linked immunosorbent assay or reverse transcription quantitative polymerase chain reaction. Phosphorylation levels of p-P38 and P38 were detected by Western blot. The level of apoptosis in BV2 cells under Aβ1-42 stress was exacerbated by miR-181c-5p mimic. Downregulated miR-181c-5p impaired the phagocytosis and degradation of Aβ by BV2 cells. The release of proinflammatory cytokines in BV2 cells with Aβ1-42 stress was alleviated by miR-181c-5p upregulation. Additionally, miR-181c-5p downregulation alleviated the phosphorylation of P38 in Aβ1-42-induced SH-SY5Y cells. In conclusion, miR-181c-5p improves the phagocytosis of Aβ by microglial cells in AD patients, thereby reducing neuroinflammation.

Complementary and alternative medicine on cognitive defects and neuroinflammation after sepsis

Sepsis-associated encephalopathy (SAE) is a common manifestation of sepsis, ranging from mild confusion and delirium to severe cognitive impairment and deep coma. SAE is associated with higher mortality and long-term outcomes, particularly substantial declines in cognitive function. The mechanisms of SAE probably include neuroinflammation that is mediated by systemic inflammation and ischemic lesions in the brain, a disrupted blood-brain barrier, oxidative stress, neurotransmitter dysfunction, and severe microglial activation. Increasing evidence suggests that complementary and alternative medicine, especially Traditional Chinese Medicine (TCM), is favorable in alleviating cognitive decline after sepsis. Here, we summarized the studies of traditional herbal remedies, TCM formulas and acupuncture therapy in animal models of neurological dysfunctions after sepsis in recent decades and reviewed their potential mechanisms.

Exploring ncRNA-mediated pathways in sepsis-induced pyroptosis

Sepsis, a potentially fatal illness caused by an improper host response to infection, remains a serious problem in the world of healthcare. In recent years, the role of ncRNA has emerged as a pivotal aspect in the intricate landscape of cellular regulation. The exploration of ncRNA-mediated regulatory networks reveals their profound influence on key molecular pathways orchestrating pyroptotic responses during septic conditions. Through a comprehensive analysis of current literature, we navigate the diverse classes of ncRNAs, including miRNAs, lncRNAs, and circRNAs, elucidating their roles as both facilitators and inhibitors in the modulation of pyroptotic processes. Furthermore, we highlight the potential diagnostic and therapeutic implications of targeting these ncRNAs in the context of sepsis, aiming to cover the method for novel and effective strategies to mitigate the devastating consequences of septic pathogenesis. As we unravel the complexities of this regulatory axis, a deeper understanding of the intricate crosstalk between ncRNAs and pyroptosis emerges, offering promising avenues for advancing our approach to sepsis intervention. The intricate pathophysiology of sepsis is examined in this review, which explores the dynamic interaction between ncRNAs and pyroptosis, a highly regulated kind of programmed cell death.

Targeting blood-brain barrier for sepsis-associated encephalopathy: Regulation of immune cells and ncRNAs

Sepsis causes significant morbidity and mortality worldwide, most surviving patients show acute or chronic mental disorders, which are known as sepsis-associated encephalopathy (SAE). SAE involves many pathological processes, including the blood-brain barrier (BBB) damage. The BBB is located at the interface between the central nervous system and the surrounding environment, which protects the central nervous system (CNS) from the invasion of exogenous molecules, harmful substances or microorganisms in the blood. Recently, a growing number of studies have indicated that the BBB destruction was involved in SAE and played an important role in SAE-induced brain injury. In the present review, we firstly reveal the pathological processes of SAE such as the neurotransmitter disorders, oxidative stress, immune dysfunction and BBB destruction. Moreover, we introduce the structure of BBB, and describe the immune cells including microglia and astrocytes that participate in the BBB destruction after SAE. Furthermore, in view of the current research on non-coding RNAs (ncRNAs), we explain the regulatory mechanism of ncRNAs including long noncoding RNAs (lncRNAs), microRNAs (miRNAs) and circular RNAs (circRNAs) on BBB in the processes of SAE. Finally, we propose some challenges and perspectives of regulating BBB functions in SAE. Hence, on the basis of these effects, both immune cells and ncRNAs may be developed as therapeutic targets to protect BBB for SAE patients.

CircRNAs in Alzheimer's disease: What are the prospects?

Circular RNAs (circRNAs) is a fascinating covalently closed circular non-coding RNA that is abundantly present in the transcriptome of eukaryotic cells. Its versatile nature allows it to participate in a multitude of pathological and physiological processes within the organism. One of its crucial functions is acting as a microRNA sponge, modulating protein transcription levels, and forming interactions with essential RNA-binding proteins. Remarkably, circRNAs demonstrates a specific enrichment in various vital areas of the brain, including the cortex, hippocampus, white matter, and photoreceptor neurons, particularly in aging organisms. This intriguing characteristic has led scientists to explore its potential as a significant biological marker of neurodegeneration, offering promising insights into neurodegenerative diseases like Alzheimer's disease (AD). In AD, there has been an interesting observation of elevated levels of circRNAs in both peripheral blood and synaptic terminals of affected individuals. This intriguing finding raises the possibility that circRNAs may have a central role in the initiation and progression of AD. Notably, different categories of circRNAs, including HDAC9, HOMER1, Cwc27, Tulp4, and PTK2, have been implicated in driving the pathological changes associated with AD through diverse mechanisms. For instance, these circRNAs have been demonstrated to contribute to the accumulation of beta-amyloid, which is a hallmark characteristic of AD. Additionally, these circRNAs contribute to the excessive phosphorylation of tau protein, a phenomenon associated with neurofibrillary tangles, further exacerbating the disease. Moreover, they are involved in aggravating neuroinflammation, which is known to play a critical role in AD's pathogenesis. Lastly, these circRNAs can cause mitochondrial dysfunction, disrupting cellular energy production and leading to cognitive impairment. As researchers delve deeper into the intricate workings of circRNAs, they hope to unlock its full potential as a diagnostic tool and therapeutic target for neurodegenerative disorders, paving the way for innovative treatments and better management of such devastating conditions.

Elucidating the mechanisms underlying astrocyte-microglia crosstalk in hippocampal neuroinflammation induced by acute diquat exposure

The transition from paraquat (PQ) to diquat (DQ), both organic dication herbicides, in China has led to significant increases in the number of acute DQ poisoning cases. Case studies have shown that acute DQ poisoning resulted in injury to the central nervous system (CNS), but the mechanism underlying the injury remains to be explored. The present study aimed to investigate how DQ influenced purinergic signaling between astrocytes and microglia and whether extracellular ATP (eATP) was involved in promoting neuroinflammation induced by acute DQ toxicity through the activation of the P2X4/NLRP3 signaling pathway. We constructed a rat model of acute DQ toxicity to observe the pathological changes in hippocampal tissues after DQ exposure and measure the expression levels of IL-1β and TNF-α in the hippocampal tissue. We also established an in vitro co-culture model of C6 astrocytes and BV-2 microglia using transwell chambers, measured the amount of eATP secreted into C6 astrocytes after DQ treatment, and assessed the inflammatory response and changes in the P2X4/NLRP3 signaling pathway in BV-2 microglia. The results showed that the neurons in the hippocampal tissue of rats exhibited loose arrangement, nuclear consolidation, and necrosis after DQ exposure, and IL-1β and TNF-α levels were signification higher in the hippocampal tissue after DQ exposure. DQ exposure to the co-cultured cells induced an increase in ATP secretion from C6 astrocytes as well as a significant increase of P2X4, NLRP3, IL-1β, and IL-18 expression in BV-2 microglia. In contrast, pretreatment of C6 astrocytes with apyrase (an ATP hydrolase) resulted in a significant decrease of P2X4, NLRP3, IL-1β, and IL-18 expression in BV-2 microglia. Furthermore, inhibition of P2X4 expression in BV-2 microglia by transfection with si-P2X4 effectively reversed the increase of NLRP3, IL-1β, and IL-18 in BV-2 microglia induced by DQ when co-cultured with C6 astrocytes. These results indicate that astrocytes can activate the P2X4/NLRP3 signaling pathway in microglia through the DQ-induced extracellular release of ATP to promote neuroinflammation in rat hippocampal tissue.

Autophagy Suppresses Ferroptosis by Degrading TFR1 to Alleviate Cognitive Dysfunction in Mice with SAE

Sepsis-associated encephalopathy (SAE) is a serious complication of sepsis that is characterized by long-term cognitive impairment, which imposes a heavy burden on families and society. However, its pathological mechanism has not been elucidated. Ferroptosis is a novel form of programmed cell death that is involved in multiple neurodegenerative diseases. In the current study, we found that ferroptosis also participated in the pathological process of cognitive dysfunction in SAE, while Liproxstatin-1 (Lip-1) effectively inhibited ferroptosis and alleviated cognitive impairment. Additionally, since an increasing number of studies have suggested the crosstalk between autophagy and ferroptosis, we further proved the essential role of autophagy in this process and demonstrated the key molecular mechanism of the autophagy-ferroptosis interaction. Currently, we showed that autophagy in the hippocampus was downregulated within 3 days of lipopolysaccharide injection into the lateral ventricle. Moreover, enhancing autophagy ameliorated cognitive dysfunction. Importantly, we found that autophagy suppressed ferroptosis by downregulating transferrin receptor 1 (TFR1) in the hippocampus, thereby alleviating cognitive impairment in mice with SAE. In conclusion, our findings indicated that hippocampal neuronal ferroptosis is associated with cognitive impairment. In addition, enhancing autophagy can inhibit ferroptosis via degradation of TFR1 to ameliorate cognitive impairment in SAE, which shed new light on the prevention and therapy for SAE.

CIRC_0002131 CONTRIBUTES TO LPS-INDUCED APOPTOSIS, INFLAMMATION, AND OXIDATIVE INJURY IN HK-2 CELLS VIA INHIBITING THE BINDING BETWEEN MIR-942-5P AND OXSR1

ABSTRACT

Background: Circular RNAs are implicated in the progression of sepsis-associated acute kidney injury (AKI). Circ_0002131 was shown to aggravate cell inflammation and oxidative stress in sepsis-induced AKI. The aim of this study was to investigate the role and underlying mechanism of circ_0002131 in sepsis-induced AKI. Methods: Cell counting Ki-8 assay was used for cell viability detection. Cell apoptosis was measured using flow cytometry. Circ_0002131, microRNA-942-5p (miR-942-5p), and oxidative stress responsive 1 (OXSR1) level analysis was performed through reverse transcription-quantitative polymerase chain reaction assay. The protein levels were examined by western blot. Inflammatory factors were determined using enzyme-linked immunosorbent assay. Oxidative injury was assessed via commercial kits. Target relation was analyzed by dual-luciferase reporter assay and RNA immunoprecipitation assay. Results: HK-2 cell viability was suppressed and apoptosis was enhanced by LPS. Circ_0002131 was highly expressed in LPS-treated HK-2 cells and sepsis-induced AKI patients. LPS-induced apoptosis, inflammation, and oxidative injury of HK-2 cells were attenuated after silence of circ_0002131. Then, miR-942-5p was identified as a target for circ_0002131, and the regulation of circ_0002131 in LPS-induced cell injury was ascribed to reduce miR-942-5p level. In addition, circ_0002131 targeted miR-942-5p to elevate OXSR1 expression. MiR-942-5p prevented LPS-evoked HK-2 cell injury via targeting OXSR1. Conclusion : All results demonstrated that circ_0002131 promoted LPS-mediated HK-2 cell injury via miR-942-5p-mediated upregulation of OXSR1, suggesting that the circ_0002131/miR-942-5p/OXSR1 axis was related to sepsis-induced AKI progression.

Non-Coding RNA in Microglia Activation and Neuroinflammation in Alzheimer's Disease

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by complex pathophysiological features. Amyloid plaques resulting from extracellular amyloid deposition and neurofibrillary tangles formed by intracellular hyperphosphorylated tau accumulation serve as primary neuropathological criteria for AD diagnosis. The activation of microglia has been closely associated with these pathological manifestations. Non-coding RNA (ncRNA), a versatile molecule involved in various cellular functions such as genetic information storage and transport, as well as catalysis of biochemical reactions, plays a crucial role in microglial activation. This review aims to investigate the regulatory role of ncRNAs in protein expression by directly targeting genes, proteins, and interactions. Furthermore, it explores the ability of ncRNAs to modulate inflammatory pathways, influence the expression of inflammatory factors, and regulate microglia activation, all of which contribute to neuroinflammation and AD. However, there are still significant controversies surrounding microglial activation and polarization. The categorization into M1 and M2 phenotypes may oversimplify the intricate and multifaceted regulatory processes in microglial response to neuroinflammation. Limited research has been conducted on the role of ncRNAs in regulating microglial activation and inducing distinct polarization states in the context of neuroinflammation. Moreover, the regulatory mechanisms through which ncRNAs govern microglial function continue to be refined. The current understanding of ncRNA regulatory pathways involved in microglial activation remains incomplete and may be influenced by spatial, temporal, and tissue-specific factors. Therefore, further in-depth investigations are warranted. In conclusion, there are ongoing debates and uncertainties regarding the activation and polarization of microglial cells, particularly concerning the categorization into M1 and M2 phenotypes. The study of ncRNA regulation in microglial activation and polarization, as well as its mechanisms, is still in its early stages and requires further investigation. However, this review offers new insights and opportunities for therapeutic approaches in AD. The development of ncRNA-based drugs may hold promise as a new direction in AD treatment.

A review on circular RNAs and bacterial infections

Bacterial infections and related diseases have been a major burden on social public health and economic stability around the world. However, the effective diagnostic methods and therapeutic approaches to treat bacterial infections are still limited. As a group of non-coding RNA, circular RNAs (circRNAs) that were expressed specifically in host cells and played a key regulatory role have the potential to be of diagnostic and therapeutic value. In this review, we systematically summarize the role of circRNAs in common bacterial infections and their potential roles as diagnostic markers and therapeutic targets.

Inhibition of sepsis-induced acute kidney injury via the circITCH-miR-579-3p-ZEB2 axis

Circular RNAs (circRNAs) are linked to the regulation of sepsis-induced acute kidney injury (AKI). However, the function of circITCH in the development of sepsis-induced AKI is still unclear. The levels of circITCH, miR-579-3p and ZEB2 were examined by real-time PCR and immunoblotting. Then, the roles of circITCH in cell viability, apoptosis, and inflammation in lipopolysaccharide (LPS)-treated HK-2 cells were evaluated. The further mechanism was investigated using rescue assays. CircITCH was downregulated in septic AKI patients and LPS-triggered HK-2 cells. CircITCH overexpression restored cell viability in LPS-treated HK-2 cells and restrained apoptosis and inflammatory cytokine production. CircITCH negatively regulated miR-579-3p, thereby upregulating ZEB2 expression. Taken together, circITCH alleviates LPS-induced HK-2 cell injury by regulating miR-579-3p/ZEB2 signal axis, which provides a theoretical basis for AKI therapy.

The miR-34b-5p-negative target Gnai2 aggravates fluorine combined with aluminum-induced apoptosis of rat offspring hippocampal neurons and NG108-15 cells

It is known that fluorine and aluminum are commonly found in the environment and that long-term overexposure can adversely affect the organism's nervous system, damaging the structure and function of brain tissue. Our previous study showed that fluorine combined with aluminum (FA) could trigger apoptosis in vitro and cause spatial learning and memory impairment and differentially expressed miRNAs (including miR-34b-5p) in the hippocampi in vivo. However, the detailed mechanism is unclear. Learning memory damage is implicated in excessive hippocampal neuron apoptosis, and miR-34b-5p participates in regulating the hippocampal neuron apoptosis. Thus, in the current research, Sprague-Dawley (SD) rats were subjected to FA, and NG108-15 control cells and NG108-15 cells pretransfected with miR-34b-5p agomir or antagomir were exposed to FA. We found that FA triggered apoptosis of rat hippocampal neurons and NG108-15 cells, increased miR-34b-5p expression, and decreased Gnai2, PKA, ERK and CREB expression. Inhibition of miR-34b-5p alleviated FA-induced NG108-15 cell apoptosis and further increased Gnai2, PKA, ERK, and CREB expression, and vice versa. Furthermore, miR-34b-5p modulated the level of Gnai2 by directly targeting its 3'-untranslated region (UTR), as verified through the dual Luciferase reporter assay. These outcomes suggested that miR-34b-5p participated in FA-induced neuronal apoptosis by targeting Gnai2 negatively, thereby inhibiting the PKA/ERK/CREB signaling pathway.

Alpinetin inhibits neuroinflammation and neuronal apoptosis via targeting the JAK2/STAT3 signaling pathway in spinal cord injury

BACKGROUND

A growing body of research shows that drug monomers from traditional Chinese herbal medicines have antineuroinflammatory and neuroprotective effects that can significantly improve the recovery of motor function after spinal cord injury (SCI). Here, we explore the role and molecular mechanisms of Alpinetin on activating microglia-mediated neuroinflammation and neuronal apoptosis after SCI.

METHODS

Stimulation of microglia with lipopolysaccharide (LPS) to simulate neuroinflammation models in vitro, the effect of Alpinetin on the release of pro-inflammatory mediators in LPS-induced microglia and its mechanism were detected. In addition, a co-culture system of microglia and neuronal cells was constructed to assess the effect of Alpinetin on activating microglia-mediated neuronal apoptosis. Finally, rat spinal cord injury models were used to study the effects on inflammation, neuronal apoptosis, axonal regeneration, and motor function recovery in Alpinetin.

RESULTS

Alpinetin inhibits microglia-mediated neuroinflammation and activity of the JAK2/STAT3 pathway. Alpinetin can also reverse activated microglia-mediated reactive oxygen species (ROS) production and decrease of mitochondrial membrane potential (MMP) in PC12 neuronal cells. In addition, in vivo Alpinetin significantly inhibits the inflammatory response and neuronal apoptosis, improves axonal regeneration, and recovery of motor function.

CONCLUSION

Alpinetin can be used to treat neurodegenerative diseases and is a novel drug candidate for the treatment of microglia-mediated neuroinflammation.

CircRTN1 stimulates HMGB1 to regulate the malignant progression of papillary thyroid cancer by sponging miR-101-3p

BACKGROUND

The important role played by circular RNA (circRNA) in promoting the progression of papillary thyroid cancer (PTC) is attracting ever more attention among medical researchers. However, what the precise contribution is of circRTN1 in PTC progression remains unclear. The study was designed to analyze the role and mechanism of circRTN1 in regulating PTC progression.

METHODS

Human PTC cell lines (TPC-1 and IHH-4) and human thyroid normal cells (Nthy-ori 3-1) were used for in vitro assays. mRNA or protein expression of circRTN1, miR-101-3p, and high mobility group box 1 (HMGB1) were detected by quantitative real-time polymerase chain reaction or western blot. Cell proliferation was investigated by cell counting kit-8 assay, cell colony formation assay, and 5-ethynyl-2'-deoxyuridine assay. Wound-healing assay and transwell invasion assay were conducted to evaluate cell migration and invasion. Dual-luciferase reporter assay and RNA immunoprecipitation assay were applied to verify the target relations between circRTN1, miR-101-3p, and HMGB1. A xenograft tumor model was established to demonstrate the effect of circRTN1 on tumor formation in vivo. An immunohistochemistry assay was used to detect protein expression of HMGB1, ki-67, E-cadherin, and vimentin.

RESULTS

In comparison with healthy thyroid tissues and cells, PTC tissues and cells displayed high circRTN1 RNA expression and high HMGB1 mRNA and protein expression but low miR-101-3p expression. Silencing of circRTN1 suppressed PTC cell proliferation, migration, and invasion in vitro. MiR-101-3p was a target of circRTN1, and the knockdown of miR-101-3p relieved circRTN1 absence-mediated suppressive effects on PTC cell malignancy. HMGB1 was identified as a target gene of miR-101-3p, and overexpressed HMGB1 almost reverted the inhibitory impacts induced by miR-101-3p mimic in PTC cells. Moreover, circRTN1 silencing hampered tumor formation in vivo.

CONCLUSION

CircRTN1 depletion impeded PTC cell malignancy via the miR-101-3p/HMGB1 pathway, which provided a possible circRNA-targeted therapeutic strategy for PTC.

Formyl peptide receptor 2 activation by mitochondrial formyl peptides stimulates the neutrophil proinflammatory response via the ERK pathway and exacerbates ischemia-reperfusion injury

BACKGROUND

Ischemia-reperfusion injury (IRI) is an inevitable process in renal transplantation that significantly increases the risk of delayed graft function, acute rejection, and even graft loss. Formyl peptide receptor 2 (FPR2) is an important receptor in multiple septic and aseptic injuries, but its functions in kidney IRI are still unclear. This study was designed to reveal the pathological role of FPR2 in kidney IRI and its functional mechanisms.

METHODS

To explore the mechanism of FPR2 in kidney IRI, the model rats were sacrificed after IRI surgery. Immunofluorescence, enzyme-linked immunosorbent assays, and western blotting were used to detect differences in the expression of FPR2 and its ligands between the IRI and control groups. WRW₄ (WRWWWW-NH2), a specific antagonist of FPR2, was administered to kidney IRI rats. Kidney function and pathological damage were detected to assess kidney injury and recovery. Flow cytometry was used to quantitatively compare neutrophil infiltration among the experimental groups. Mitochondrial formyl peptides (mtFPs) were synthesized and administered to primary rat neutrophils together with the specific FPR family antagonist WRW₄ to verify our hypothesis in vitro. Western blotting and cell function assays were used to examine the functions and signaling pathways that FPR2 mediates in neutrophils.

RESULTS

FPR2 was activated mainly by mtFPs during the acute phase of IRI, mediating neutrophil migration and reactive oxygen species production in the rat kidney through the ERK1/2 pathway. FPR2 blockade in the early phase protected rat kidneys from IRI.

CONCLUSIONS

mtFPs activated FPR2 during the acute phase of IRI and mediated rat kidney injury by activating the migration and reactive oxygen species generation of neutrophils through the ERK1/2 pathway.

Circular RNA protein tyrosine kinase 2 aggravates pyroptosis and inflammation in septic lung tissue by promoting microRNA-766/eukaryotic initiation factor 5A axis-mediated ATP efflux

PURPOSE

Sepsis is characterized by an acute inflammatory response to infection, often with multiple organ failures, especially severe lung injury. This study was implemented to probe circular RNA (circRNA) protein tyrosine kinase 2 (circPTK2)-associated regulatory mechanisms in septic acute lung injury (ALI).

METHODS

A cecal ligation and puncture-based mouse model and an lipopolysaccharides (LPS)-based alveolar type II cell (RLE-6TN) model were generated to mimic sepsis. In the two models, inflammation- and pyroptosis-related genes were measured.

RESULTS

The degree of lung injury in mice was analyzed by hematoxylin and eosin (H&E) staining and the apoptosis was by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling staining. In addition, pyroptosis and toxicity were detected in cells. Finally, the binding relationship between circPTK2, miR-766, and eukaryotic initiation factor 5A (eIF5A) was detected. Data indicated that circPTK2 and eIF5A were up-regulated and miR-766 was down-regulated in LPS-treated RLE-6TN cells and lung tissue of septic mice. Lung injury in septic mice was ameliorated after inhibition of circPTK2.

CONCLUSIONS

It was confirmed in the cell model that knockdown of circPTK2 effectively ameliorated LPS-induced ATP efflux, pyroptosis, and inflammation. Mechanistically, circPTK2 mediated eIF5A expression by competitively adsorbing miR-766. Taken together, circPTK2/miR-766/eIF5A axis ameliorates septic ALI, developing a novel therapeutic target for the disease.

Non-coding RNA and n6-methyladenosine modification play crucial roles in neuropathic pain

After peripheral nerve injury, pain signals are transmitted from primary sensory neurons in the dorsal root ganglion (DRG) to the central nervous system. Epigenetic modification affects neuropathic pain through alterations in the gene expression in pain-related areas and glial cell activation. Recent studies have shown that non-coding RNA and n6-methyladenosine (m6A) methylation modification play pivotal regulatory roles in the occurrence and maintenance of neuropathic pain. Dysregulation of the RNA m6A level via dynamic changes in methyltransferase and demethylase after central or peripheral nerve injury commonly regulates pain-associated genes, contributing to the induction and maintenance of neuropathic pain. The dynamic process has significant implications for the development and maintenance of neuropathic pain. However, the underlying mechanisms by which non-coding RNA and m6A RNA modification regulate neuropathic pain are not well-characterized. This article elucidates the multiple mechanisms of non-coding RNA and m6A methylation in the context of neuropathic pain, and summarizes its potential functions as well as recent advances.

Decoding competitive endogenous RNA regulatory network in postoperative cognitive dysfunction

Postoperative cognitive dysfunction (POCD) is a common postoperative neurological complication in elderly patients. Circular RNAs (circRNAs) are abundant in the mammalian brain and can probably regulate cognitive function. However, the competitive endogenous RNA (ceRNA) regulatory network in POCD remains illiterate. Transcriptomic signatures in the hippocampus of POCD mice derived from the Gene Expression Omnibus (GEO) dataset GSE190880, GSE95070, and GSE115440 were used to identify the circRNA, miRNA, and mRNA expression profiles of POCD mice compared with controls, respectively. A set of differentially expressed RNAs, including 119 circRNAs, 33 miRNAs, and 49 mRNAs were identified. Transcript validation showed the enhanced expression of circ_0001634, circ_0001345, and circ_0001493. A ceRNA regulatory network composed of three circRNAs, three miRNAs, and six mRNAs was established. The hub mRNAs in the ceRNA network were further found to be involved in the hormone catabolic process and regulation of canonical Wnt signaling pathway, revealing their crucial role in POCD. Finally, three miRNAs and four mRNAs were verified by qRT-PCR. These results based on bioinformatics and PCR array suggest that circ_0001634/miR-490-5p/Rbm47, circ_0001634/miR-490-5p/Sostdc1, circ_0001634/miR-7001-5p/Sostdc1, circ_0001345/miR-7001-5p/Sostdc1, and circ_0001493/miR-7001-5p/Sostdc1 may be novel diagnostic biomarkers and therapeutic targets for POCD.

Sepsis-Induced Brain Dysfunction: Pathogenesis, Diagnosis, and Treatment

Dysregulated host response to infection, which cause life-threatening organ dysfunction, was defined as sepsis. Sepsis can cause acute and long-term brain dysfunction, namely, sepsis-associated encephalopathy (SAE) and cognitive impairment. SAE refers to changes in consciousness without direct evidence of central nervous system infection. It is highly prevalent and may cause poor outcomes in sepsis patients. Cognitive impairment seriously affects the life quality of sepsis patients and increases the medical burden. The pathogenesis of sepsis-induced brain dysfunction is mainly characterized by the interaction of systemic inflammation, blood-brain barrier (BBB) dysfunction, neuroinflammation, microcirculation dysfunction, and brain dysfunction. Currently, the diagnosis of sepsis-induced brain dysfunction is based on clinical manifestation of altered consciousness along with neuropathological examination, and the treatment is mainly involves controlling sepsis. Although treatments for sepsis-induced brain dysfunction have been tested in animals, clinical treat sepsis-induced brain dysfunction is still difficult. Therefore, we review the underlying mechanisms of sepsis-induced brain injury, which mainly focus on the influence of systemic inflammation on BBB, neuroinflammation, brain microcirculation, and the brain function, which want to bring new mechanism-based directions for future basic and clinical research aimed at preventing or ameliorating brain dysfunction.

Role of circRNA in pathogenesis of Alzheimers disease

Circular RNA (circRNA) is a covalently closed-loop non-coding RNA that exists widely in the transcriptome of eukaryotic cells. It participates in a variety of pathophysiological processes by acting as a microRNA sponge, regulating the level of protein transcription, and interacting with RNA binding proteins. CircRNA is enriched in the cortex, hippocampus, brain white matter, and photoreceptor neurons of aging bodies, and they can be used as a biomarker for neural senescence. The expression levels of circRNA in peripheral blood and synapses in Alzheimer's disease (AD) patients are increased, which are involved in the occurrence and prognosis of AD. Different circRNAs such as HDAC9, Homer1, Cwc27, Tulp4, and PTK2 can lead to AD pathological changes via increasing amyloid-β deposition, promoting tau protein hyperphosphorylation, aggravating neuroinflammation and mitochondrial dysfunction, which result in the cognitive decline.

Overexpression of circ PTK2 suppresses the progression of nonalcoholic fatty liver disease via the miR-200c/SIK2/PI3K/Akt axis

Excessive hepatic lipid accumulation is involved in the pathogenesis of nonalcoholic fatty liver disease (NAFLD). A previous study showed that the circular RNA (circRNA) PTK2 was significantly downregulated in NAFLD mice. However, the detailed function of circ PTK2 in NAFLD remains unclear. A high-fat diet (HFD) was used to establish a mouse model of NAFLD, and free fatty acid (FFA) treatment was used to establish an in vitro model of NAFLD. Oil red O staining was used to evaluate lipid accumulation. The pathological changes in mice were observed by HE staining. Western blotting and RT-qPCR were applied to assess protein and mRNA levels, respectively. A dual luciferase reporter assay and RIP were used to explore the relationship among circ PTK2, miR-200c and SIK2. Circ PTK2 and SIK2 were downregulated and miR-200c was upregulated in NAFLD. Upregulation of circ PTK2 reversed lipid accumulation in FFA-treated HepG2 cells. Moreover, circ PTK2 bound to miR-200c, and SIK2 was identified as the direct target of miR-200c. Moreover, the miR-200c inhibitor-induced decrease in lipid accumulation was reversed by SIK2 knockdown. Furthermore, the impact of circ PTK2 overexpression on PI3K/Akt signaling was partially reversed by SIK2 silencing. Circ PTK2 overexpression alleviates NAFLD development via the miR-200c/SIK2/PI3K/Akt axis. Thus, our work might provide new methods for NAFLD treatment.

High Mobility Group Proteins in Sepsis

Sepsis, a systemic inflammatory response disease, is the most severe complication of infection and a deadly disease. High mobility group proteins (HMGs) are non-histone nuclear proteins binding nucleosomes and regulate chromosome architecture and gene transcription, which act as a potent pro-inflammatory cytokine involved in the delayed endotoxin lethality and systemic inflammatory response. HMGs increase in serum and tissues during infection, especially in sepsis. A growing number of studies have demonstrated HMGs are not only cytokines which can mediate inflammation, but also potential therapeutic targets in sepsis. To reduce sepsis-related mortality, a better understanding of HMGs is essential. In this review, we described the structure and function of HMGs, summarized the definition, epidemiology and pathophysiology of sepsis, and discussed the HMGs-related mechanisms in sepsis from the perspectives of non-coding RNAs (microRNA, long non-coding RNA, circular RNA), programmed cell death (apoptosis, necroptosis and pyroptosis), drugs and other pathophysiological aspects to provide new targets and ideas for the diagnosis and treatment of sepsis.

The Role of MicroRNA in DNA Damage Response

DNA is essential for the development and function of organisms. A number of factors affect DNA integrity and cause DNA damages, such as ultraviolet light, ionizing radiation and hydrogen peroxide. DNA damages activate a series of intracellular reactions, called DNA damage response, which play a crucial role in the pathogenesis of cancers and other diseases. MiRNA is a type of evolutionarily conserved non-coding RNA and affects the expression of target genes by post-transcriptional regulation. Increasing evidences suggested that the expression of some miRNAs was changed in tumor cases. MiRNAs may participate in DNA damage response and affect genomic stability via influencing the processes of cell cycle, DNA damage repair and apoptosis, thus ultimately impact on tumorigenesis. Therefore, the role of miRNA in DNA damage response is reviewed, to provide a theoretical basis for the mechanism of miRNAs' effects on DNA damage response and for the research of new therapies for diseases.

Effects of dexmedetomidine on cognitive dysfunction and neuroinflammation via the HDAC2/HIF-1α/PFKFB3 axis in a murine model of postoperative cognitive dysfunction

Inhibition of histone deacetylase (HDAC) may be a useful approach in the treatment of disorders characterized by cognitive dysfunction. Dexmedetomidine (DEX), an α2-adrenoceptor (α2-AR) agonist, has demonstrated neuroprotective effects. Here, we attempted to investigate the protective effects of DEX on postoperative cognitive dysfunction (POCD) involving HDAC2. Male C57BL/6 mice were selected to develop a POCD model, where HDAC2, HIF-1α, and PFKFB3 expression was quantified. DEX was administered before POCD modeling. Then the cognitive function of POCD mice was evaluated with the open field and Y-maze tests. Meanwhile, lipopolysaccharide (LPS) was employed to induce BV-2 microglial cells to simulate the inflammatory response. The contents of TNF-α, IL-6, and IL-10 were measured by enzyme-linked immunosorbent assay (ELISA) in mouse serum and BV-2 cell supernatant. Abundant expression of HDAC2, HIF-1α, and PFKFB3 was confirmed in POCD mice (p < 0.05). Cognitive dysfunction in POCD mice could be alleviated following pharmacological inhibition of HDAC2 by FK228 (p < 0.05). Mechanistically, HDAC2 upregulated HIF-1α and PFKFB3 and promoted the secretion of inflammatory factors in LPS-exposed BV-2 cells (p < 0.05). DEX attenuated neuroinflammation and the resulting cognitive dysfunction by decreasing HDAC2 expression and HIF-1α-dependent PFKFB3 upregulation in POCD mice (p < 0.05). In conclusion, DEX-regulated HDAC2 may play an inhibitory role in mice with POCD through regulation of the HIF-1α/PFKFB3 axis.

Circular RNAs in the pathogenesis of sepsis and their clinical implications: A narrative review

Introduction: Sepsis is defined as a life-threatening complication that occurs when the body responds to an infection attacking the host. Sepsis rapidly progresses and patients deteriorate and develop septic shock, with multiple organ failure, if not promptly treated. Currently no effective therapy is available for sepsis; therefore, early diagnosis is crucial to decrease the high mortality rate. Genome-wide expression analyses of patients in critical conditions have confirmed that the expression levels of the majority of genes are changed, suggesting that the molecular basis of sepsis is at the gene level. This review aims to elucidate the role of circular (circ) RNAs in the pathogenesis of sepsis and sepsis-induced organ damage. In addition, the feasibility of using circRNAs as novel diagnostic biomarkers for sepsis is also discussed, as well as circRNA-based therapy. Method: This narrative review is based on a literature search using Medline database. Search terms used were “circular RNAs and sepsis”, “circRNAs and sepsis”, “non-coding RNAs and sepsis”, “ncRNAs and sepsis”, “circRNAs and septic pathogenesis”, “circRNAs and septic model”, “circRNAs and septic shock” and “circRNAs, biomarker, and sepsis”. Results: Numerous studies indicate that circRNAs might exert pivotal roles in regulating the immune system of the host against various pathogens, such as bacteria and viruses. Dysregulation of circRNA expression levels has been confirmed as an early event in sepsis and associated with the inflammatory response, immunosuppression and coagulation dysfunction. This impairment in regulation eventually leads to multiple organ dysfunctions, including of the kidneys, lungs and heart. Conclusion: By investigating the regulation of circRNAs in sepsis, new molecular targets for the diagnosis and intervention of sepsis can be identified. Such an understanding will be important for the development of therapeutic drugs. Keywords: Acute kidney injury, biomarker, circRNAs, inflammation, sepsis

MicroRNA-181c-5p modulates phagocytosis efficiency in bone marrow-derived macrophages

OBJECTIVE AND DESIGN

Phagocytosis and clearance of apoptotic cells are essential for inflammation resolution, efficient wound healing, and tissue homeostasis. MicroRNAs are critical modulators of macrophage polarization and function. The current study aimed to investigate the role of miR-181c-5p in macrophage phagocytosis.

MATERIALS AND METHODS

miR-181c-5p was identified as a potential candidate in microRNA screening of RAW264.7 macrophages fed with apoptotic cells. To investigate the role of miR-181c-5p in phagocytosis, the expression of miR-181c-5p was assessed in phagocyting bone marrow-derived macrophages. Phagocytosis efficiency was measured by fluorescence microscopy. Gain- and loss-of-function studies were performed using miR-181c-5p-specific mimic and inhibitor. The expression of the phagocytosis-associated genes and proteins of interest was evaluated by RT² profiler PCR array and western blotting, respectively.

RESULTS

miR-181c-5p expression was significantly upregulated in the phagocyting macrophages. Furthermore, mimic-induced overexpression of miR-181c-5p resulted in the increased phagocytic ability of macrophages. Moreover, overexpression of miR-181c-5p resulted in upregulation of WAVE-2 in phagocyting macrophages, suggesting that miR-181c-5p may regulate cytoskeletal arrangement during macrophage phagocytosis.

CONCLUSION

Altogether, our data provide a novel function of miR-181c-5p in macrophage biology and suggest that targeting macrophage miR-181c-5p in injured tissues might improve clearance of dead cells and lead to efficient inflammation resolution.

Regulatory Role of Non-Coding RNAs on Immune Responses During Sepsis

Sepsis is resulted from a systemic inflammatory response to bacterial, viral, or fungal agents. The induced inflammatory response by these microorganisms can lead to multiple organ system failure with devastating consequences. Recent studies have shown altered expressions of several non-coding RNAs such as long non-coding RNAs (lncRNAs), microRNAs (miRNAs) and circular RNAs (circRNAs) during sepsis. These transcripts have also been found to participate in the pathogenesis of multiple organ system failure through different mechanisms. NEAT1, MALAT1, THRIL, XIST, MIAT and TUG1 are among lncRNAs that participate in the pathoetiology of sepsis-related complications. miR-21, miR-155, miR-15a-5p, miR-494-3p, miR-218, miR-122, miR-208a-5p, miR-328 and miR-218 are examples of miRNAs participating in these complications. Finally, tens of circRNAs such as circC3P1, hsa_circRNA_104484, hsa_circRNA_104670 and circVMA21 and circ-PRKCI have been found to affect pathogenesis of sepsis. In the current review, we describe the role of these three classes of noncoding RNAs in the pathoetiology of sepsis-related complications.