mRNA and Long Non-coding RNA Expression Profiles in Rats Reveal Inflammatory Features in Sepsis-Associated Encephalopathy

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.

Electroacupuncture Alleviates Neuroinflammation by Inhibiting the HMGB1 Signaling Pathway in Rats with Sepsis-Associated Encephalopathy

Sepsis-Associated Encephalopathy (SAE) is common in sepsis patients, with high mortality rates. It is believed that neuroinflammation is an important mechanism involved in SAE. High mobility group box 1 protein (HMGB1), as a late pro-inflammatory factor, is significantly increased during sepsis in different brain regions, including the hippocampus. HMGB1 causes neuroinflammation and cognitive impairment through direct binding to advanced glycation end products (RAGE) and Toll-like receptor 4 (TLR4). Electroacupuncture (EA) at Baihui (GV20) and Zusanli (ST36) is beneficial for neurological diseases and experimental sepsis. Our study used EA to treat SAE induced by lipopolysaccharide (LPS) in male Sprague-Dawley rats. The Y maze test was performed to assess working memory. Immunofluorescence (IF) and Western blotting (WB) were used to determine neuroinflammation and the HMGB1 signaling pathway. Results showed that EA could improve working memory impairment in rats with SAE. EA alleviated neuroinflammation by downregulating the hippocampus's HMGB1/TLR4 and HMGB1/RAGE signaling, reducing the levels of pro-inflammatory factors, and relieving microglial and astrocyte activation. However, EA did not affect the tight junctions' expression of the blood-brain barrier (BBB) in the hippocampus.

Comprehensive analysis of mRNAs, lncRNAs and circRNAs in the early phase of microglial activation

Sepsis-associated encephalopathy (SAE) is a common complication of sepsis that may seriously affect the prognosis and quality of life of patients with sepsis. Microglial activation is vital to the neuroinflammation and the pathology of SAE. In the present study, in vitro cultured BV-2 microglial cells stimulated with lipopolysaccharide (LPS) were employed as a model of microglia activation. The altered profiles of long noncoding (lnc)RNAs, circular (circ)RNAs and mRNAs in BV-2 cells after 4 h of LPS exposure were arrayed by using the Agilent competing endogenous (ce)RNA Microarray Chip. Using fold change >2 and P<0.05 as the cutoff criteria, 1,135 mRNAs and 2,488 lncRNAs were determined to be upregulated and 630 mRNAs and 744 lncRNAs to be downregulated. The number of differentially expressed circRNAs was lower, with 140 upregulated and 123 downregulated. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analysis of DE mRNAs suggested that inflammatory responses, as well as lipid metabolism, were involved in microglial activation. Furthermore, analyses of ceRNA networks of the lncRNA-miRNA-mRNA or circRNA-miRNA-mRNA interrelations were performed. The present study revealed a multitude of novel candidate mRNAs, lncRNAs and circRNAs involved in microglial activation, which may improve the current knowledge on neuroinflammation and provide potential therapeutic targets for SAE.

Long Non-Coding RNAs as Biomarkers and Therapeutic Targets in Sepsis

Sepsis, an infection-induced systemic inflammatory disorder, is often accompanied by multiple organ dysfunction syndromes with high incidence and mortality rates, and those who survive are often left with long-term sequelae, bringing great burden to social economy. Therefore, novel approaches to solve this puzzle are urgently needed. Previous studies revealed that long non-coding RNAs (lncRNAs) have exerted significant influences on the process of sepsis. The aim of this review is to summarize our understanding of lncRNAs as potential sepsis-related diagnostic markers and therapeutic targets, and provide new insights into the diagnosis and treatment for sepsis. In this study, we also introduced the current diagnostic markers of sepsis and discussed their limitations, while review the research advances in lncRNAs as promising biomarkers for diagnosis and prognosis of sepsis. Furthermore, the roles of lncRNAs in sepsis-induced organ dysfunction were illustrated in terms of different organ systems. Nevertheless, further studies should be carried out to elucidate underlying molecular mechanisms and pathological process of sepsis.

Long non-coding RNA: An underlying bridge linking neuroinflammation and central nervous system diseases

Central nervous system (CNS) diseases are responsible for a large proportion of morbidity and mortality worldwide. CNS diseases caused by intrinsic and extrinsic stimuli stimulate the resident immune cells including microglia and astrocyte, resulting in neuroinflammation that exacerbates the progression of diseases. Recent evidence reveals the aberrant expression patterns of long non-coding RNAs (lncRNAs) in the damaged tissues following CNS diseases. It was also proposed that lncRNAs possessed immune-modulatory activities by directly or indirectly affecting various effector proteins including transcriptional factor, acetylase, protein kinase, phosphatase, etc. In addition, lncRNAs can form a sophisticated network by interacting with other molecules to regulate the expression or activation of downstream immune response pathways. However, the major roles of lncRNAs in CNS pathophysiologies are still elusive, especially in neuroinflammation. Herein, we tend to review some potential roles of lncRNAs in modulating neuroinflammation based on current evidence in various CNS diseases, in order to provide novel explanations for the initiation and progression of CNS diseases and help to establish therapeutic strategies targeting neuroinflammation.

Long Noncoding RNA: Regulatory Mechanisms and Therapeutic Potential in Sepsis

Sepsis is a life-threatening organ dysfunction caused by a dysregulated host response to infection and is characterized by a hyperinflammatory state accompanied by immunosuppression. Long noncoding RNAs (lncRNAs) are noncoding RNAs longer than 200 nucleotides and have important roles in mediating various biological processes. Recently, lncRNAs were found to exert both promotive and inhibitory immune functions in sepsis, thus participating in sepsis regulation. Additionally, several studies have revealed that lncRNAs are involved in sepsis-induced organ dysfunctions, including cardiovascular dysfunction, acute lung injury, and acute kidney injury. Considering the lack of effective biomarkers for early identification and specific treatment for sepsis, lncRNAs may be promising biomarkers and even targets for sepsis therapies. This review systematically highlights the recent advances regarding the roles of lncRNAs in sepsis and sheds light on their use as potential biomarkers and treatment targets for sepsis.

The Expanding Regulatory Mechanisms and Cellular Functions of Long Non-coding RNAs (lncRNAs) in Neuroinflammation

LncRNAs have emerged as important regulatory molecules in biological processes. They serve as regulators of gene expression pathways through interactions with proteins, RNA, and DNA. LncRNA expression is altered in several diseases of the central nervous system (CNS), such as neurodegenerative disorders, stroke, trauma, and infection. More recently, it has become clear that lncRNAs contribute to regulating both pro-inflammatory and anti-inflammatory pathways in the CNS. In this review, we discuss the molecular pathways involved in the expression of lncRNAs, their role and mechanism of action during gene regulation, cellular functions, and use of lncRNAs as therapeutic targets during neuroinflammation in CNS disorders.

Reducing LncRNA-5657 expression inhibits the brain inflammatory reaction in septic rats

Our preliminary study found that the long noncoding RNA (LncRNA)-5657 can reduce the expression of inflammatory factors during inflammatory reactions in rat glial cells. However, the role played by LncRNA-5657 during septic brain injury remains unclear. In the present study, rat models of septic encephalopathy were established by cecal ligation and puncture, and then the rats were treated with a hippocampal injection small hairpin RNA (shRNA) against LncRNA-5657 (sh-LnCRNA-5657). The sh-LncRNA-5657 treatment reduced the level of neuronal degeneration and necrosis in the rat hippocampus, reduced the immunoreactivities of aquaporin 4, heparanase, and metallopeptidase-9, and lowered the level of tumor necrosis factor-alpha. Glial cells were pre-treated with sh-LncRNA-5657 and then treated with 1 µg/mL lipopolysaccharide. Sh-LncRNA-5657 transfection decreased the expression of LncRNA-5657 in lipopolysaccharide-treated glial cells and decreased the mRNA and protein levels of tumor necrosis factor-alpha, interleukin-1β, and interleukin-6. These findings suggested that LncRNA-5657 expression can significantly reduce the inflammatory reaction during septic encephalopathy and induce protective effects against this disease. This study was approved by the Institutional Ethics Committee at the First Affiliated Hospital of Nanchang University of China (approval No. 2017-004) in 2017.

Expression Profiling of Long Noncoding RNA and Messenger RNA in a Cecal Ligation and Puncture-Induced Colon Injury Mouse Model

Background

Emerging evidence reveals that long noncoding RNAs (lncRNAs) play important roles in the pathogenesis of sepsis. However, the detailed regulatory mechanisms of lncRNAs or whether certain lncRNA could serve as a biomarker in the septic colon remains unclear. The aim of this study was to investigate the profiles of lncRNAs and mRNAs in the septic colon through whole-transcriptome RNA sequencing and to reveal the associated regulatory mechanism.

Method and Result

We established a mouse model of sepsis by cecal ligation and puncture (CLP). Colon samples were collected upon CLP or sham surgery after 24 h. Whole-transcriptome RNA sequencing was performed to profile the relative expressions of lncRNAs and mRNAs. 808 lncRNAs and 1509 mRNAs were differentially found in the septic group compared with the sham group. Bioinformatics analysis including Gene Ontology (GO) analysis and Kyoto Encyclopedia of Genes and Genomes pathway analysis (KEGG) was performed to predict the potential functions of these RNAs. GO analysis showed that the altered lncRNAs were enriched and involved in multiple immune responses, which may be a response to sepsis stress. KEGG analysis indicated that upregulated lncRNAs were significantly enriched in the p53 signaling pathway, NF-κB signaling pathway, and HIF-1 signaling pathway. Downregulated lncRNAs were mostly found to be involved in tight junction, leukocyte transendothelial migration, and HIF-1 signaling pathway.

Conclusion

Our results indicate that these altered lncRNAs and mRNAs may have crucial roles in the pathogenesis of sepsis. This study could contribute to extending the understanding of the function of lncRNAs in sepsis, which may help in searching for new diagnostic biomarkers and therapeutic targets to treat sepsis.

Knockdown of long non-coding RNA SOX2OT downregulates SOX2 to improve hippocampal neurogenesis and cognitive function in a mouse model of sepsis-associated encephalopathy

Background

Aberrant hippocampal neurogenesis is an important pathological feature of sepsis-associated encephalopathy. In the current study, we examined the potential role of the long noncoding RNA (lncRNA) sex-determining region Y-box 2 (SOX2) overlapping transcript (SOX2OT), a known regulator of adult neurogenesis in sepsis-induced deficits in hippocampal neurogenesis and cognitive function.

Methods

Sepsis was induced in adult C57BL/6 J male mice by cecal ligation and perforation (CLP) surgery. Randomly selected CLP mice were transfected with short interfering RNAs (siRNAs) against SOX2OT or SOX2, or with scrambled control siRNA. Cognitive behavior was tested 8–12 days post-surgery using a Morris water maze. Western blotting and RT-qPCR were used to determine expression of SOX2, Ki67, doublecortin (DCX), nestin, brain lipid-binding protein, and glial fibrillary acidic protein (GFAP) in the hippocampus. The number of bromodeoxyuridine (BrdU)⁺/DCX⁺ cells, BrdU⁺/neuronal nuclei (NeuN)⁺ neurons, and BrdU⁺/GFAP⁺ glial cells in the dentate gyrus were assessed by immunofluorescence.

Results

CLP mice showed progressive increases in SOX2OT and SOX2 mRNA levels on days 3, 7, and 14 after CLP surgery, accompanied by impaired cognitive function. Sepsis led to decrease in all neuronal markers in the hippocampus, except GFAP. Immunofluorescence confirmed the decreased numbers of BrdU⁺/DCX⁺ cells and BrdU⁺/NeuN⁺ neurons, and increased numbers of BrdU⁺/GFAP⁺ cells. SOX2OT knockdown partially inhibited the effects of CLP on levels of SOX2 and neuronal markers, neuronal populations in the hippocampus, and cognitive function. SOX2 deficiency recapitulated the effects of SOX2OT knockdown.

Conclusion

SOX2OT knockdown improves sepsis-induced deficits in hippocampal neurogenesis and cognitive function by downregulating SOX2 in mice. Inhibiting SOX2OT/SOX2 signaling may be effective for treating or preventing neurodegeneration in sepsis-associated encephalopathy.

Long non-coding RNA profiling in LPS-induced intestinal inflammation model: New insight into pathogenesis

LPS can induce an inflammatory immune response in the intestine, and long non-coding RNA (lncRNA) is involved in the process of inflammatory disease. However, the biological role of lncRNA in the intestinal inflammation of piglets remains unclear. In this study, the lncRNA expression profile of the ileal mucosa of piglets challenged by LPS was analysed using lncRNA sequencing. In total, 112 novel lncRNAs were predicted, of which 58 were up-regulated and 54 down-regulated following LPS challenge. Expression of 15 selected lncRNAs was validated by quantitative PCR. We further investigated the target genes of lncRNA that were enriched in the signalling pathways involved in the inflammatory immune response by utilising Gene Ontology and Kyoto Encyclopaedia of Genes and Genomes analysis, with cell adhesion molecules and mTOR signalling pathway identified. In addition, the co-expression networks between the differentially expressed lncRNAs and the target mRNAs were constructed, with seven core lncRNAs identified, which also demonstrated that the relationship between lncRNAs and the target genes was highly correlated. Our study offers important information about the lncRNAs of the mucosal immune system in piglets and provides new insights into the inflammatory mechanism of LPS challenge, which might serve as a novel target to control intestinal inflammation.

Microarray analysis of lncRNA expression in rabies virus infected human neuroblastoma cells

Rabies, caused by the rabies virus (RABV), is the oldest known zoonotic infectious disease. Although the molecular mechanisms of RABV pathogenesis have been investigated extensively, the interactions between host and RABV are not clearly understood. It is now known that long non-coding RNAs (lncRNAs) participate in various physiological and pathological processes, but their possible roles in the host response to RABV infection remain to be elucidated. To better understand the pathogenesis of RABV, RNAs from RABV-infected and uninfected human neuroblastoma cells (SK-N-SH) were analyzed using human lncRNA microarrays. We identified 896 lncRNAs and 579 mRNAs that were differentially expressed after infection, indicating a potential role for lncRNAs in the immune response to RABV. Differentially expressed RNAs were examined using Gene Ontology (GO) analysis and were tentatively assigned to biological pathways using the Kyoto Encyclopedia of Genes and Genomes (KEGG). A lncRNA-mRNA-transcription factor co-expression network was constructed to relate lncRNAs to regulatory factors and pathways that may be important in virus-host interactions. The network analysis suggests that E2F4, TAF7 and several lncRNAs function as transcriptional regulators in various signaling pathways. This study is the first global analysis of lncRNA and mRNA co-expression during RABV infection, provides deeper insight into the mechanism of RABV pathogenesis, and reveals promising candidate for future investigation.

Research Progress on the Role and Mechanism of Action of Activin A in Brain Injury

Activin A belongs to the transforming growth factor superfamily and has a variety of biological functions. Studies have revealed that activin A can regulate the body's immune and inflammatory responses and participate in the regulation of cell death. In addition, activin A also has neurotrophic function and plays an important role in the repair of brain damage. This article summarizes recent advances in understanding the role and mechanism of action of activin A in brain injury and provides new hints into the application of activin A in the treatment of brain injury.