Characterization of Circular RNA and microRNA Profiles in Septic Myocardial Depression: a Lipopolysaccharide-Induced Rat Septic Shock Model

The role of programmed cell death in diabetic foot ulcers

Diabetic foot ulcer, is a chronic complication afflicting individuals with diabetes, continue to increase worldwide, immensely burdening society. Programmed cell death, which includes apoptosis, autophagy, ferroptosis, necroptosis and pyroptosis, has been increasingly implicated in the pathogenesis of diabetic foot ulcer. This review is based on an exhaustive examination of the literature on 'programmed cell death' and 'diabetic foot ulcers' via PubMed. The findings revealed that natural bioactive compounds, noncoding RNAs and certain proteins play crucial roles in the healing of diabetic foot ulcers through various forms of programmed cell death, including apoptosis, autophagy, ferroptosis and pyroptosis.

Long Noncoding RNA and mRNA Expression Profiles in Rats with LPS-induced Myocardial Dysfunction

Background

Sepsis is an uncontrolled systemic inflammatory response. Long noncoding RNAs (lncRNAs) are involved in the pathogenesis of sepsis. However, little is known about the roles of lncRNAs in sepsis-induced myocardial dysfunction.

Objective

We aimed to determine the regulatory mechanism of lncRNAs in sepsis-induced myocardial dysfunction.

Methods

In this study, we analysed the lncRNA and mRNA expression profiles using microarray analysis. Gene Ontology, Kyoto Encyclopedia of Genes and Genomes, protein-protein interaction network, and gene set enrichment analysis were used to evaluate the data. We also constructed coding and noncoding coexpression and competing endogenous RNA networks to investigate the mechanisms.

Results

In vivo lipopolysaccharide -induced sepsis rat model was established. A total of 387 lncRNAs and 1,952 mRNAs were identified as significantly changed in the left ventricle. Kyoto Encyclopedia of Genes and Genomes analysis of mRNAs showed that the upregulated genes were mainly enriched in the "complement and coagulation cascade pathway" and "immune-related biological processes" terms. Eight significantly changed lncRNAs detected by RT-qPCR may be responsible for these processes. A competing endogenous RNA network was generated, and the results indicated that eight lncRNAs were related to the "calcium ion binding" process.

Conclusion

These results demonstrate that crosstalk between lncRNAs and mRNAs may play important roles in the development of sepsis-induced myocardial dysfunction.

LncRNA-mRNA expression profile and functional network of vascular dysfunction in septic rats

BACKGROUND

We used microarrays to analyse the changes in long non-coding RNAs (lncRNAs) and mRNAs in aorta tissue in model rats with lipopolysaccharide-induced sepsis and determined the lncRNA-mRNA and lncRNA-miRNA-mRNA functional networks.

METHODS

Wistar rats were intraperitoneally injected with lipopolysaccharide, and the lncRNA and mRNA expression profiles in the aorta were evaluated using microarrays. The functions of the differentially expressed mRNAs were analysed using Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses. We then constructed coding/non-coding co-expression and competing endogenous RNA networks to study the mechanisms related to sepsis in rats.

RESULTS

We identified 503 differentially expressed lncRNAs and 2479 differentially expressed mRNAs in the model rats with lipopolysaccharide-induced sepsis. Mitochondrial fission process 1 (MTFP1) was the most significantly down-regulated mRNA. Bioinformatics analysis showed that the significantly down-regulated mRNAs in the sepsis models were in pathways related to mitochondrial structure, function, and energy metabolism. Coding/non-coding co-expression and competing endogenous RNA analyses were conducted using 12 validated lncRNAs in combination with all mRNAs. The coding/non-coding co-expression analysis showed that the 12 validated lncRNAs were mainly regulatory factors for abnormal energy metabolism, including mitochondrial structure damage and aberrant mitochondrial dynamics. The competing endogenous RNA analysis revealed that the potential functions of these 12 lncRNAs might be related to the inflammatory response.

CONCLUSION

We determined the differentially expressed lncRNAs and mRNAs in the aorta of septic rats using microarrays. Further studies on these lncRNAs will help elucidate the mechanism of sepsis at the genetic level and may identify potential therapeutic targets.

Non-coding RNAs: Role in diabetic foot and wound healing

Diabetic foot ulcer (DFU) and poor wound healing are chronic complications in patients with diabetes. The increasing incidence of DFU has resulted in huge pressure worldwide. Diagnosing and treating this condition are therefore of great importance to control morbidity and improve prognosis. Finding new markers with potential diagnostic and therapeutic utility in DFU has gathered increasing interest. Wound healing is a process divided into three stages: Inflammation, proliferation, and regeneration. Non-coding RNAs (ncRNAs), which are small protected molecules transcribed from the genome without protein translation function, have emerged as important regulators of diabetes complications. The deregulation of ncRNAs may be linked to accelerated DFU development and delayed wound healing. Moreover, ncRNAs can be used for therapeutic purposes in diabetic wound healing. Herein, we summarize the role of microRNAs, long ncRNAs, and circular RNAs in diverse stages of DFU wound healing and their potential use as novel therapeutic targets.

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.

The circular RNA hsa_circ_0003091 regulates sepsis-induced lung injury by sponging the miR-149/Smad2 axis

Sepsis-induced acute lung injury (ALI) is a severe cause of death. Increasing evidence has identified circular RNAs (circRNAs) acting as critical regulators of human diseases. However, their expression pattern and underlying mechanisms in ALI remain unclear. Herein, we screened the circRNAs of ALI patients and constructed a lung injury murine model using lipopolysaccharides (LPS) induction. Functional analyses of targeted circRNA were performed in vivo and in vitro. Then, the downstream miRNA and mRNA of specific circRNAs were identified. Compared to healthy subjects, 35 circRNAs were upregulated and 9 circRNAs were downregulated in sepsis patients. The top 10 differentially expressed circRNAs were selected for validation and has_circ_0003091 was selected. The ALI mice presented significantly elevated has_circ_0003091 (mmu_circ_0015268). The functional analysis revealed that mmu_circ_0015268 contributed to the pulmonary injury, cell apoptosis, inflammatory responses, and endothelial activation in the ALI murine model. On the other hand, silencing mmu_circ_0015268 showed protective effects in LPS-treated mice and PMVECs. Furthermore, mmu_circ_0015268 sponged miR-149 to upregulate the expression of its target Smad2. In summary, we demonstrated that has_circ_0003091 might be a novel target for the management and treatment of sepsis-induced ALI.

Integrated insights into the mechanisms underlying sepsis-induced myocardial depression using a quantitative global proteomic analysis

Sepsis-induced myocardial depression is common among patients in the intensive care unit; however, the exact mechanisms underlying this condition remain unclear. We investigated differences in the expression of specific proteins and determined the potential functions of the proteins in a rat model of lipopolysaccharide-induced septic shock. Left ventricular tissue was excised from 16 rats (sepsis group, 8; control group, 8) and analysed. Quantitative analysis of the global proteome was performed using 4D label-free technique. Bioinformatic analyses were conducted based on differentially expressed (DE) proteins. Parallel reaction monitoring (PRM) validation for selected proteins and western blotting for selected global protein modifications in heart tissues were also performed. As a result, out of 3653 proteins identified, 108 were expressed differentially between the two groups. The bioinformatic analyses revealed that DE proteins play important roles in metabolism- and immune-related pathways. PRM results supported the plausibility and reliability of the proteomics data. Modification of heart tissue acetyllysine, succinyllysine, 2-hydroxyisobutyryllysine, and lactyllysine revealed clear differences between the two groups, indicating the effects of protein modification. Our study suggested that expression patterns of global proteins in heart tissue were different between the two groups. These results provide new valuable information on the possible mechanisms underlying sepsis-induced myocardial depression. SIGNIFICANCE: The expression patterns of global proteins in the heart tissues of patients with sepsis and control groups remain unknown. In this study, we used the 4D label-free proteomics technique to compare differentially expressed (DE) proteins between the sepsis and control groups. We identified 3653 proteins, 108 of which were expressed differentially between the sepsis and control groups. Further bioinformatic analyses revealed that DE proteins play critical roles in metabolism- and immune-related processes and pathways. Interestingly, modification of heart tissue acetyllysine, succinyllysine, 2-hydroxyisobutyryllysine, and lactyllysine revealed clear differences between the sepsis and control groups. The findings of this study improve our understanding of the basic molecular mechanisms underlying sepsis-induced myocardial depression.

Identification and Validation of Ferroptosis-Related Biomarkers in Septic Cardiomyopathy via Bioinformatics Analysis

Septic cardiomyopathy (SCM) is a cardiac dysfunction caused by severe sepsis and septic shock that increases the risk of heart failure and death and its molecular mechanism remains unclear. Ferroptosis, a novel form of programmed cell death, has been reported to be present in the heart tissue of patients with sepsis, which demonstrated that ferroptosis may be a potential mechanism of myocardial injury in SCM. Therefore, we explored the role of ferroptosis-related genes (FRGs) in SCM and aimed to identify pivotal ferroptosis-related targets in SCM and potential therapeutic targets involved in the pathological process of SCM. To explore the regulatory mechanisms of ferroptosis in SCM, we identified differentially expressed genes (DEGs) in SCM and FRGs by bioinformatics analysis, and further identified hub genes. And the crucial microRNAs (miRNAs)-FRGs regulatory network was subsequently constructed. Finally, several candidate drugs associated with the hub genes were predicted, and Real-time quantitative reverse Transcription PCR (qRT-PCR) and western blotting analysis were performed to confirm the abnormal expression of hub genes. In this study, we identified several FRGs that may be involved in the pathogenesis of SCM, which helps us further clarify the role of ferroptosis in SCM and deeply understand the molecular mechanisms and potential therapeutic targets of SCM.

CircTLK1 modulates sepsis-induced cardiomyocyte apoptosis via enhancing PARP1/HMGB1 axis-mediated mitochondrial DNA damage by sponging miR-17-5p

Introduction

Septic cardiomyopathy is a common complication of sepsis with high morbidity and mortality, but lacks specific therapy. This study aimed to reveal the role of circTLK1 and its potential mechanisms in septic cardiomyopathy.

Materials and Methods

The in vitro and in vivo models of septic cardiomyopathy were established. Cell viability and apoptosis were detected by CCK8, TUNEL and flow cytometry, respectively. LDH, CK, SOD, MDA, ATP, 8‐OHdG, NAD+/NADH ratio, ROS level, mitochondrial membrane potential and cytochrome C distribution were evaluated using commercial kits. qRT‐PCR and western blotting were performed to detect RNA and protein levels. Mitochondrial DNA (mtDNA) copy number and transcription were assessed by quantitative PCR. Dual‐luciferase assay, RNA immunoprecipitation and co‐immunoprecipitation were performed to verify the interaction between circTLK1/PARP1 and miR‐17‐5p.

Results

CircTLK1, PARP1 and HMGB1 were up‐regulated in the in vitro and in vivo models of septic cardiomyopathy. CircTLK1 inhibition restrained LPS‐induced up‐regulation of PARP1 and HMGB1. Moreover, circTLK1 knockdown repressed sepsis‐induced mtDNA oxidative damage, mitochondrial dysfunction and consequent cardiomyocyte apoptosis by inhibiting PARP1/HMGB1 axis in vitro and in vivo. In addition, circTLK1 enhanced PARP1 expression via sponging miR‐17‐5p. Inhibition of miR‐17‐5p abolished the protective effects of circTLK1 silencing on oxidative mtDNA damage and cardiomyocyte apoptosis.

Conclusion

CircTLK1 sponged miR‐17‐5p to aggravate mtDNA oxidative damage, mitochondrial dysfunction and cardiomyocyte apoptosis via activating PARP1/HMGB1 axis during sepsis, indicating that circTLK1 may be a putative therapeutic target for septic cardiomyopathy.

Lipopolysaccharide Alters the m6A Epitranscriptomic Tagging of RNAs in Cardiac Tissue

N6-methyladenosine (m⁶A) modification plays important roles in the pathology of a variety of diseases. However, the roles of m⁶A modification in sepsis-induced myocardial dysfunction are not well defined. Rats were divided into control and lipopolysaccharide (LPS)-induced sepsis group. Global m⁶A levels of left ventricle tissue were measured by LC-MS/MS, and transcriptome-wide m⁶A modifications were profiled using epitranscriptomic microarrays (mRNAs and lncRNAs). Bioinformatics analysis was conducted to understand the functional implications of m⁶A modifications during sepsis. Methylated lncRNAs and mRNAs were measured by m⁶A single-base site qPCR. The global m⁶A levels in left ventricle tissue were significantly decreased in the LPS group. While 27 transcripts (23 mRNAs and four lncRNAs) were hypermethylated, 46 transcripts (39 mRNAs and 7 lncRNAs) were hypomethylated in the LPS group. The mRNA expression of writers and readers was significantly decreased in the LPS group. The m⁶A modification of Clec1b, Stk38l and Tnfrsf26 was associated with platelet activation and apoptotic pathways. Moreover, the decrease in m⁶A modification of lncRNA XR_346,771 may be related to cation import in cardiac tissue. Our data provide novel information regarding changes to m⁶A modifications in cardiac tissue during sepsis, and m⁶A modifications might be promising therapeutic targets.

Overexpression of Peroxisome Proliferator-Activated Receptor γ Coactivator 1-α Protects Cardiomyocytes from Lipopolysaccharide-Induced Mitochondrial Damage and Apoptosis

Mitochondrial damage is considered one of the main pathogenetic mechanisms in septic cardiomyopathy. Peroxisome proliferator-activated receptor γ coactivator 1-α (PGC-1α) is critical for maintaining energy homeostasis in different organs and in various physiological and pathological states. It is also a key regulator gene in mitochondrial metabolism. In this study, we investigated whether regulation of the PGC-1α gene had protective effects on septic cardiomyopathy. We developed a rat model of septic cardiomyopathy. H9c2 myocardiocytes were treated with lipopolysaccharide (LPS) and PGC-1α expression measured. PGC-1α-overexpressing lentivirus was used to transfect H9c2 cells. ZLN005 was used to activate PGC-1α. The effect of the inhibition of PGC-1α expression on myocardial cell injury and its underlying mechanisms were also explored. Cell viability was measured by CCK-8 assay. Mitochondrial damage was determined by measuring cellular ATP, reactive oxygen species, and the mitochondrial membrane potential. An apoptosis analysis kit was used to measure cellular apoptosis. Mitochondrial DNA was extracted and real-time PCR performed. LC3B, mitochondrial transcription factor A (TFA), P62, Bcl2, and Bax were determined by immunofluorescence. LC3B, TFA, P62, Parkin, PTEN-induced putative kinase 1, and PGC-1α proteins were determined by Western blotting. We found mitochondrial damage and apoptotic cells in the myocardial tissue of rats with septic cardiomyopathy and in LPS-treated cardiomyocytes. PGC-1α expression was decreased in the late phase of septic cardiomyopathy and in LPS-treated cardiomyocytes. PGC-1α activation by ZLN005 and PGC-1α overexpression reduced apoptosis in myocardiocytes after LPS incubation. PGC-1α gene overexpression alleviated LPS-induced cardiomyocyte mitochondrial damage by activating mitochondrial biogenesis and autophagy functions. Our study indicated that mitochondrial damage and apoptosis occurred in septic cardiomyopathy and LPS-treated cardiomyocytes. The low expression level of PGC-1α protein may have contributed to this damage. By activating the expression of PGC-1α, apoptosis was reduced in cardiomyocytes. The underlying mechanism may be that PGC-1α can activate mitochondrial biogenesis and autophagy functions, reducing mitochondrial damage and thereby reducing apoptosis.

[Role and mechanism of circular RNA in brain injury induced by inflammation in preterm mice: a preliminary study]

OBJECTIVE

To determine the association of circular RNA (circRNA) and circRNA-microRNA (miRNA) network regulation with brain injury induced by inflammation in preterm mice.

METHODS

Pregnant mice were treated with intraperitoneally injected lipopolysaccharide to establish a preterm mouse model of brain injury induced by inflammation (inflammation preterm group with 3 mice). Preterm mice born to normal pregnant mice by cesarean section were selected as controls (non-inflammation preterm group with 3 mice). The gene microarray technique was used to screen out the circRNAs associated with brain injury in preterm mice. The miRNA target prediction software was used to predict the binding sites between circRNAs and miRNAs and analyze the regulatory mechanism.

RESULTS

A total of 365 differentially expressed circRNAs were screened out between the inflammation preterm and non-inflammation preterm groups (fold change > 1.5, P < 0.05), among which there were 206 upregulated circRNAs and 159 downregulated circRNAs. Further analysis of the circRNAs with a fold change of > 4 showed that these circRNAs could bind to miRNAs and regulate their activity, thereby regulating the expression of the genes associated with the nervous system.

CONCLUSIONS

Inflammation induces a significant change in the expression profile of circRNAs in the brain tissue of mice, and the change in the expression of circRNAs plays an important role in brain injury induced by inflammation and subsequent brain development in preterm mice.

MAPK interacting serine/threonine kinase 1 (MKNK1), one target gene of miR-223-3p, correlates with neutrophils in sepsis based on bioinformatic analysis

Sepsis, resulting from a harmful or damaging response to infection, is a complex and severe disease that causes high mortality. Three independent expression profiles of miRNA – GSE94717, GSE149764, and GSE101639 – were collected and integrated to analyze miRNAs associated with sepsis. One miRNA, miR-223-3p, was detected significantly downregulated in patients with sepsis. The upregulated miR-223-3p target genes in patients with sepsis were enriched in central carbon metabolism associated with HIF-1 signaling and galactose metabolism. Specially, three HIF-1 signaling genes – hypoxia-inducible factor 1-alpha (HIF1A), hexokinase 2 (HK2), and MAP kinase-interacting serine/threonine-protein kinase 1 (MKNK1) – were found significantly upregulated in patients with sepsis. Additionally, MKNK1 expression was downregulated in septic responders to early therapeutic treatments. Neutrophils were significantly accumulated in patients with sepsis and decreased in responders after therapy; MKNK1 was significantly positively correlated with neutrophils. Our findings indicate MKNK1, one targets of miR-223-3p, might be involved in sepsis via regulating the neutrophils abundance by mediating the expression inflammation factors.

Inhibition of micro RNA miR-122-5p prevents lipopolysaccharide-induced myocardial injury by inhibiting oxidative stress, inflammation and apoptosis via targeting GIT1

Myocardial injury resulting from sepsis is the leading cause of death worldwide. Micro RNA miR-122-5p is involved in various physiological and pathological processes and is highly expressed in the heart of septic rats. However, its function in sepsis-caused myocardial injury remains elusive. Herein, a rat model of septic myocardial injury was established by intraperitoneal injection of lipopolysaccharide (LPS), and cardiomyocyte H9c2 was exposed to LPS to induce sepsis-related inflammatory injury in vitro. Inhibition of miR-122-5p suppressed LPS-triggered myocardial injury evidenced by decreased heart weight index (HWI), reduced inflammatory cell infiltration and cell rupture, and reduced cardiac marker enzymes cTnI and LDH. MiR-122-5p inhibition inhibited ROS production and enhanced the activities of antioxidant enzymes CAT, SOD and GSH-px in LPS-treated rats and H9c2 cells. MiR-122-5p inhibition reduced the production of pro-inflammatory cytokines TNF-α, IL-6 and IL-1β, and inhibited cell apoptosis along with decreased cleaved-caspase 3 induced by LPS. Moreover, increased GIT1 expression was found following miR-122-5p inhibition. We further verified GIT1 as a target of miR-122-5p, and silencing GIT1 partially reversed the benefits of miR-122-5p loss in LPS-injured H9c2 cells. The HO-1 and NQO-1 expression and Nrf-2 activation were enhanced by miR-122-5p inhibition, which was reversed by GIT1 depletion, indicating the involvement of Nrf-2/HO-1 signaling in regulating miR-122-5p/GIT1-mediated cardioprotection. Taken together, our data suggest that inhibition of miR-122-5p may mitigate sepsis-triggered myocardial injury through inhibiting inflammation, oxidative stress and apoptosis via targeting GIT1, which provides a possible therapeutic target 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.

Comparative transcriptome analysis of transcripts of uncertain coding potential in septic myocardial depression

BACKGROUND

Septic shock with myocardial depression is very common in intensive care units. However, the exact molecular mechanisms underlying sepsis-induced myocardial depression remain unclear. Whether the profiles of transcripts of uncertain coding potential (TUCPs) differ between patients with and without myocardial depression is also unknown. Our study aimed to find expression differences between groups of TUCPs and determine their potential functions in a preclinical model.

METHODS

We generated rat models of hypodynamic septic shock induced by lipopolysaccharide. A total of 12 rats were established and left ventricular tissue from each was collected. We performed RNA-seq to identify TUCPs in each sample. Transcripts with an corrected P value of < 0.05 were defined as differentially expressed (DE). We also performed GO terms and KEGG analysis to identify the potential functions of DE TUCPs.

RESULTS

A total of 4,851 TUCPs were identified in heart samples, 85 of which were expressed differently between the sepsis and control groups. Further bioinformatic analyses suggested that TUCPs play important roles in myocardial contraction, energy regulation, and metabolic processes, and are also involved in the regulation of several pathways.

CONCLUSION

Our results demonstrate that TUCPs both participate in and mediate the pathological process of myocardial depression. Our study improves the understanding of the basic molecular mechanisms underlying myocardial depression from a novel perspective.

Non-Coding RNAs and Extracellular Vehicles: Their Role in the Pathogenesis of Gestational Diabetes Mellitus

Gestational diabetes mellitus (GDM) is defined as glucose intolerance with onset or first recognition in the second or third trimester of pregnancy. GDM has a considerable impact on health outcomes of the mother and offspring during pregnancy, delivery, and beyond. Although the exact mechanism regarding GDM remains unclear, numerous studies have suggested that non-coding RNAs, including long non-coding (lnc)RNAs, microRNAs, and circular RNAs, were involved in the pathogenesis of GDM in which they played vital regulatory roles. Additionally, several studies have revealed that extracellular vehicles also participated in the pathogenesis of GDM, highlighting their important role in this disease. Considering the lack of effective biomarkers for the early identification of and specific treatment for GDM, non-coding RNAs and extracellular vehicles may be promising biomarkers and even targets for GDM therapies. This review provides an update on our understanding of the role of non-coding RNAs and extracellular vehicles in GDM. As our understanding of the function of lncRNAs and extracellular vehicles improves, the future appears promising for their use as potential biomarkers and treatment targets for GDM in clinical practice.

MicroRNAs and Sepsis-Induced Cardiac Dysfunction: A Systematic Review

Sepsis is a severe condition characterized by systemic inflammation. One of the most involved organs in sepsis is the heart. On the other hand, heart failure and dysfunction are some of the most leading causes of death in septic patients. miRNAs are short single-strand non-coding ribonucleic acids involved in the regulation of gene expression on a post-transcriptional phase, which means they are a part of the epigenetic process. Recently, researchers have found that miRNA expression in tissues and blood differs depending on different conditions. Because of this property, their use as serum sepsis biomarkers has also been explored. A narrative review is carried out to gather and summarize what is known about miRNAs' influence on cardiac dysfunction during sepsis. When reviewing the literature, we found at least 77 miRNAs involved in cardiac inflammation and dysfunction during sepsis. In the future, miRNAs may be used as early sepsis-induced cardiac dysfunction biomarkers or as new drug targets. This could help clinicians to early detect, prevent, and treat cardiac damage. The potential role of miRNAs as new diagnostic tools and therapeutic strategies worth deepening the complex network between non-coding RNA and biological pathways. Additional studies are needed to further investigate their role in sepsis-induced myocardium injury.

Circular RNA in cardiovascular disease: Expression, mechanisms and clinical prospects

Circular RNAs (circRNAs) are a group of covalently closed, endogenous, non‐coding RNAs, which exist widely in human tissues including the heart. Increasing evidence has shown that cardiac circRNAs play crucial regulatory roles in cardiovascular diseases (CVDs). In this review, we aimed to provide a systemic understanding of circRNAs with a special emphasis on the cardiovascular system. We have summarized the current research on the classification, biogenesis and properties of circRNAs as well as their participation in the pathogenesis of CVDs. CircRNAs are conserved, stable and have specific spatiotemporal expression; thus, they have been accepted as a potential diagnostic marker or an incremental prognostic biomarker for CVDs.

Overexpression of miR-150-5p Alleviates Apoptosis in Sepsis-Induced Myocardial Depression

Sepsis-induced myocardial depression has high mortality and is very common in intensive care units. Previous studies have found that microRNAs play an important role in regulating sepsis-induced myocardial depression. miR-150-5p is involved in many biological processes; however, the mechanism underlying its role in sepsis-induced myocardial depression is still unclear. In this study, we generated rat models of septic shock induced by lipopolysaccharide. Whole genomic RNA sequencing was performed on 12 left ventricles collected after LPS treatment to identify miRNAs. Most of the target genes of the differently expressed microRNAs were involved in apoptosis, according to Gene Ontology. We also observed apoptosis in the heart tissue and in H9C2 cardiomyocytes stimulated with lipopolysaccharide, indicating that cell apoptosis may be an important mechanism in sepsis-induced myocardial depression. Furthermore, the expression of miR-150-5p was reduced, and overexpression of miR-150-5p with mimics resulted in a decrease in apoptosis, decreased expression of cleaved caspase3 and Bax, and increased expression of Bcl-2. Additionally, after H9C2 cells were transfected with miR-150-5p mimics or an inhibitor, the expression of Akt2 decreased or increased, respectively. These findings suggest that miR-150-5p can alleviate apoptosis and may be a novel therapeutic target for sepsis-induced myocardial depression.

Circular RNAs in Sepsis: Biogenesis, Function, and Clinical Significance

Sepsis is a life-threatening condition that occurs when the body responds to an infection that damages it is own tissues. The major problem in sepsis is rapid, vital status deterioration in patients, which can progress to septic shock with multiple organ failure if not properly treated. As there are no specific treatments, early diagnosis is mandatory to reduce high mortality. Despite more than 170 different biomarkers being postulated, early sepsis diagnosis and prognosis remain a challenge for clinicians. Recent findings propose that circular RNAs (circRNAs) may play a prominent role in regulating the patients’ immune system against different pathogens, including bacteria and viruses. Mounting evidence also suggests that the misregulation of circRNAs is an early event in a wide range of diseases, including sepsis. Despite circRNA levels being altered in sepsis, the specific mechanisms controlling the dysregulation of these noncoding RNAs are not completely elucidated, although many factors are known to affect circRNA biogenesis. Therefore, there is a need to explore the molecular pathways that lead to this disorder. This review describes the role of this new class of regulatory RNAs in sepsis and the feasibility of using circRNAs as diagnostic biomarkers for sepsis, opening up new avenues for circRNA-based medicine.

Identification of circRNA and mRNA expression profiles and functional networks of vascular tissue in lipopolysaccharide-induced sepsis

Sepsis is the most common cause of death in intensive care units. This study investigated the circular RNA (circRNA) and mRNA expression profiles and functional networks of the aortic tissue in sepsis. We established a lipopolysaccharide (LPS)‐induced rat sepsis model. High‐throughput sequencing was performed on the aorta tissue to identify differentially expressed (DE) circRNAs and mRNAs, which were validated by real‐time quantitative polymerase chain reaction (RT‐qPCR). Bioinformatic analysis was carried out and coding and non‐coding co‐expression (CNC) and competing endogenous RNA (ceRNA) regulatory networks were constructed to investigate the mechanisms. In total, 373 up‐regulated and 428 down‐regulated circRNAs and 2063 up‐regulated and 2903 down‐regulated mRNAs were identified. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses of mRNAs showed that the down‐regulated genes were mainly enriched in the process of energy generation. CNC and ceRNA regulatory networks were constructed with seven DE circRNAs. The results of functional enrichment analysis of CNC target genes revealed the important role of circRNAs in inflammatory response. The ceRNA network also highlighted the significant enrichment in calcium signalling pathway. Significant alterations in circRNAs and mRNAs were observed in the aortic tissue of septic rats. In addition, CNC and ceRNA networks were established.

MicroRNAs in Inflammatory Heart Diseases and Sepsis-Induced Cardiac Dysfunction: A Potential Scope for the Future?

Background: MicroRNAs (miRNAs) are small, single-stranded RNA sequences that regulate gene expression on a post-transcriptional level. In the last few decades, various trials have investigated the diagnostic and therapeutic potential of miRNAs in several disease entities. Here, we provide a review of the available evidence on miRNAs in inflammatory heart diseases (myocarditis, endocarditis, and pericarditis) and sepsis-induced cardiac dysfunction. Methods: Systematic database research using the PubMed and Medline databases was conducted between July and September 2019 using predefined search terms. The whole review was conducted based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Results: In total, 131 studies were screened, 96 abstracts were read, and 69 studies were included in the review. Discussion: In the future, circulating miRNAs could serve as biomarkers for diagnosis and disease monitoring in the context of inflammatory heart diseases and sepsis-induced cardiac dysfunction. Considering the promising results of different animal models, certain miRNAs could also emerge as novel therapeutic approaches in this setting.

The Glucocorticoid Receptor in Cardiovascular Health and Disease

The glucocorticoid receptor is a member of the nuclear receptor family that controls many distinct gene networks, governing various aspects of development, metabolism, inflammation, and the stress response, as well as other key biological processes in the cardiovascular system. Recently, research in both animal models and humans has begun to unravel the profound complexity of glucocorticoid signaling and convincingly demonstrates that the glucocorticoid receptor has direct effects on the heart and vessels in vivo and in vitro. This research has contributed directly to improving therapeutic strategies in human disease. The glucocorticoid receptor is activated either by the endogenous steroid hormone cortisol or by exogenous glucocorticoids and acts within the cardiovascular system via both genomic and non-genomic pathways. Polymorphisms of the glucocorticoid receptor are also reported to influence the progress and prognosis of cardiovascular disease. In this review, we provide an update on glucocorticoid signaling and highlight the critical role of this signaling in both physiological and pathological conditions of the cardiovascular system. With increasing in-depth understanding of glucocorticoid signaling, the future is promising for the development of targeted glucocorticoid treatments and improved clinical outcomes.