Hsa-miR-346 plays a role in the development of sepsis by downregulating SMAD3 expression and is negatively regulated by lncRNA MALAT1

Roles of lncRNAs in NF-κB-Mediated Macrophage Inflammation and Their Implications in the Pathogenesis of Human Diseases

Over the past century, molecular biology's focus has transitioned from proteins to DNA, and now to RNA. Once considered merely a genetic information carrier, RNA is now recognized as both a vital element in early cellular life and a regulator in complex organisms. Long noncoding RNAs (lncRNAs), which are over 200 bases long but do not code for proteins, play roles in gene expression regulation and signal transduction by inducing epigenetic changes or interacting with various proteins and RNAs. These interactions exhibit a range of functions in various cell types, including macrophages. Notably, some macrophage lncRNAs influence the activation of NF-κB, a crucial transcription factor governing immune and inflammatory responses. Macrophage NF-κB is instrumental in the progression of various pathological conditions including sepsis, atherosclerosis, cancer, autoimmune disorders, and hypersensitivity. It orchestrates gene expression related to immune responses, inflammation, cell survival, and proliferation. Consequently, its malfunction is a key contributor to the onset and development of these diseases. This review aims to summarize the function of lncRNAs in regulating NF-κB activity in macrophage activation and inflammation, with a particular emphasis on their relevance to human diseases and their potential as therapeutic targets. The insights gained from studies on macrophage lncRNAs, as discussed in this review, could provide valuable knowledge for the development of treatments for various pathological conditions involving macrophages.

Role of Macrophage lncRNAs in Mediating Inflammatory Processes in Atherosclerosis and Sepsis

Long noncoding RNAs (lncRNAs) are molecules >200 bases in length without protein-coding functions implicated in signal transduction and gene expression regulation via interaction with proteins or RNAs, exhibiting various functions. The expression of lncRNAs has been detected in many cell types, including macrophages, a type of immune cell involved in acute and chronic inflammation, removal of dead or damaged cells, and tissue repair. Increasing evidence indicates that lncRNAs play essential roles in macrophage functions and disease development. Additionally, many animal studies have reported that blockage or modulation of lncRNA functions alleviates disease severity or morbidity rate. The present review summarizes the current knowledge regarding lncRNAs expressed in macrophages, focusing on their molecular targets and the biological processes regulated by them during the development of inflammatory diseases such as atherosclerosis and sepsis. Possible application of this information to lncRNA-targeting therapy is also discussed. The studies regarding macrophage lncRNAs described in this review can help provide valuable information for developing treatments for various pathological conditions involving macrophages.

Identification of potential biomarkers and pathways for sepsis using RNA sequencing technology and bioinformatic analysis

Long non-coding RNAs (lncRNAs) has been proven by many to play a crucial part in the process of sepsis. To obtain a better understanding of sepsis, the molecular biomarkers associated with it, and its possible pathogenesis, we obtained data from RNA-sequencing analysis using serum from three sepsis patients and three healthy controls (HCs). Using edgeR (one of the Bioconductor software package), we identified 1118 differentially expressed mRNAs (DEmRNAs) and 1394 differentially expressed long noncoding RNAs (DElncRNAs) between sepsis patients and HCs. We identified the biological functions of these disordered genes using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) signaling pathway analyses. The GO analysis showed that the homophilic cell adhesion via plasma membrane adhesion molecules was the most significantly enriched category. The KEGG signaling pathway analysis indicated that the differentially expressed genes (DEGs) were most significantly enriched in retrograde endocannabinoid signaling. Using STRING, a protein-protein interaction network was also created, and Cytohubba was used to determine the top 10 hub genes. To examine the relationship between the hub genes and sepsis, we examined three datasets relevant to sepsis that were found in the gene expression omnibus (GEO) database. PTEN and HIST2H2BE were recognized as hub gene in both GSE4607, GSE26378, and GSE9692 datasets. The receiver operating characteristic (ROC) curves indicate that PTEN and HIST2H2BE have good diagnostic value for sepsis. In conclusion, this two hub genes may be biomarkers for the early diagnosis of sepsis, our findings should deepen our understanding of the pathogenesis of sepsis.

Expression of MicroRNAs in Sepsis-Related Organ Dysfunction: A Systematic Review

Sepsis is a critical condition characterized by increased levels of pro-inflammatory cytokines and proliferating cells such as neutrophils and macrophages in response to microbial pathogens. Such processes lead to an abnormal inflammatory response and multi-organ failure. MicroRNAs (miRNA) are single-stranded non-coding RNAs with the function of gene regulation. This means that miRNAs are involved in multiple intracellular pathways and thus contribute to or inhibit inflammation. As a result, their variable expression in different tissues and organs may play a key role in regulating the pathophysiological events of sepsis. Thanks to this property, miRNAs may serve as potential diagnostic and prognostic biomarkers in such life-threatening events. In this narrative review, we collect the results of recent studies on the expression of miRNAs in heart, blood, lung, liver, brain, and kidney during sepsis and the molecular processes in which they are involved. In reviewing the literature, we find at least 122 miRNAs and signaling pathways involved in sepsis-related organ dysfunction. This may help clinicians to detect, prevent, and treat sepsis-related organ failures early, although further studies are needed to deepen the knowledge of their potential contribution.

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.

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.

Potential Roles of Exosomal lncRNAs in the Intestinal Mucosal Immune Barrier

The intestinal mucosal immune barrier protects the host from the invasion of foreign pathogenic microorganisms. Immune cells and cytokines in the intestinal mucosa maintain local and systemic homeostasis by participating in natural and adaptive immunity. Deficiency of the intestinal mucosal immune barrier is associated with a variety of intestinal illnesses. Exosomes are phospholipid bilayer nanovesicles that allow cell-cell communication by secreting physiologically active substances including proteins, lipids, transcription factors, mRNAs, micro-RNAs (miRNAs), and long noncoding RNAs (lncRNAs). Exosomal lncRNAs are involved in immune cell differentiation and the modulation of the immune response. This review briefly introduces the potential role of exosomal lncRNAs in the intestinal mucosal immune barrier and discusses their relevance to intestinal illnesses.

Knockdown of lncRNA MALAT1 ameliorates acute kidney injury by mediating the miR-204/APOL1 pathway

Background

Acute kidney injury (AKI) was characterized by loss of renal function, associated with chronic kidney disease, end‐stage renal disease, and length of hospital stay. Long non‐coding RNAs (lncRNAs) participated in AKI development and progression. Here, we aimed to investigate the roles and mechanisms of lncRNA MALAT1 in AKI.

Methods

AKI serum samples were obtained from 129 AKI patients. ROC analysis was conducted to confirm the diagnostic value of MALAT1 in differentiating AKI from healthy volunteers. After hypoxic treatment on HK‐2 cells, the expressions of inflammatory cytokines, MALAT1, miR‐204, APOL1, p65, and p‐p65, were measured by RT‐qPCR and Western blot assays. The targeted relationship between miR‐204 and MALAT1 or miR‐204 and APOL1 was determined by luciferase reporter assay and RNA pull‐down analysis. After transfection, CCK‐8, flow cytometry, and TUNEL staining assays were performed to evaluate the effects of MALAT1 and miR‐204 on AKI progression.

Results

From the results, lncRNA MALAT1 was strongly elevated in serum samples from AKI patients, with the high sensitivity and specificity concerning differentiating AKI patients from healthy controls. In vitro, we established the AKI cell model after hypoxic treatment. After experiencing hypoxia, we found significantly increased MALAT1, IL‐1β, IL‐6, and TNF‐α expressions along with decreased miR‐204 level. Moreover, the targeted relationship between MALAT1 and miR‐204 was confirmed. Silencing of MALAT1 could reverse hypoxia‐triggered promotion of HK‐2 cell apoptosis. Meanwhile, the increase of IL‐1β, IL‐6, and TNF‐α after hypoxia treatment could be repressed by MALAT1 knockdown as well. After co‐transfection with MALAT1 silencing and miR‐204 inhibition, we found that miR‐204 could counteract the effects of MALAT1 on HK‐2 cell progression and inflammation after under hypoxic conditions. Finally, NF‐κB signaling was inactivated while APOL1 expression was increased in HK‐2 cells after hypoxia treatment, and lncRNA MALAT1 inhibition reactivated NF‐κB signaling while suppressed APOL1 expression by sponging miR‐204.

Conclusions

Collectively, these results illustrated that knockdown of lncRNA MALAT1 could ameliorate AKI progression and inflammation by targeting miR‐204 through APOL1/NF‐κB signaling.

lncRNA MIR155HG Accelerates the Progression of Sepsis via Upregulating MEF2A by Sponging miR-194-5p

Long noncoding RNA MIR155HG exerts important effects in the progression of multiple diseases. This study investigated the functions of MIR155HG in sepsis development. Blood samples were collected from 28 patients with sepsis and 28 without sepsis. The murine cardiac muscle cell line (HL-1) and macrophage cell line (RAW 264.7) treated with lipopolysaccharide (LPS) were used as the in vitro sepsis models. The levels of MIR155HG, miR-194-5p, and MEF2A were determined using real-time-quantitative polymerase chain reaction. Cell counting kit-8 and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) assays were used to assess cell viability and apoptosis, respectively. The association between miR-194-5p and MIR155HG or MEF2A was confirmed using a dual-luciferase reporter assay. The levels of inflammatory cytokines were detected using enzyme-linked immunosorbent assay (ELISA). In this study, we demonstrated that MIR155HG expression was significantly increased in sepsis blood samples, RAW 264.7, and HL-1 cells treated with LPS. Silencing of MIR155HG promoted cell viability and obstructed cell apoptosis and inflammation of RAW 264.7 and HL-1 cells treated with LPS. MiR-194-5p depletion abrogated cell viability promotion and suppressive effect on cell apoptosis and inflammation caused by MIR155HG knockdown. In addition, MIR155HG upregulated MEF2A through interaction with miR-194-5p. Finally, rescue assays indicated that MEF2A overexpression abolished the inhibitory effect on sepsis progression induced by MIR155HG deletion. In conclusion, MIR155HG promotes sepsis progression in an in vitro sepsis model by modulating the miR-194-5p/MEF2A axis. This discovery provides a promising biomarker for sepsis therapy.

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 Role of Long Non-coding RNAs in Sepsis-Induced Cardiac Dysfunction

Sepsis is a syndrome with life-threatening organ dysfunction induced by a dysregulated host response to infection. The heart is one of the most commonly involved organs during sepsis, and cardiac dysfunction, which is usually indicative of an extremely poor clinical outcome, is a leading cause of death in septic cases. Despite substantial improvements in the understanding of the mechanisms that contribute to the origin and responses to sepsis, the prognosis of sepsis-induced cardiac dysfunction (SICD) remains poor and its molecular pathophysiological changes are not well-characterized. The recently discovered group of mediators known as long non-coding RNAs (lncRNAs) have presented novel insights and opportunities to explore the mechanisms and development of SICD and may provide new targets for diagnosis and therapeutic strategies. LncRNAs are RNA transcripts of more than 200 nucleotides with limited or no protein-coding potential. Evidence has rapidly accumulated from numerous studies on how lncRNAs function in associated regulatory circuits during SICD. This review outlines the direct evidence of the effect of lncRNAs on SICD based on clinical trials and animal studies. Furthermore, potential functional lncRNAs in SICD that have been identified in sepsis studies are summarized with a proven biological function in research on other cardiovascular diseases.

LncRNA: A Potential Research Direction in Intestinal Barrier Function

Long non-coding RNAs (lncRNAs) are transcripts longer than 200 nucleotides and play important roles in a variety of diseases. LncRNAs are involved in many biologic processes including cell differentiation, development, and apoptosis. The intestinal barrier is considered one of the most important protective barriers in humans. Severe damage or dysfunction of the intestinal barrier may be associated with the occurrence and development of many diseases, such as inflammatory bowel disease and ulcerative colitis. LncRNAs have been found to be associated with intestinal barrier function in some studies, which are at an early stage. In this review, we introduce the roles of LncRNAs in the intestinal barrier and investigate the possibility of lncRNAs as a research field in the intestinal barrier.