CircRNA_103765 acts as a proinflammatory factor via sponging miR-30 family in Crohn's disease

Exploring the impact of circular RNA on ALS progression: A systematic review

Amyotrophic lateral sclerosis is a neurodegenerative disease that damages motor neurons and causes gradual muscular weakening and paralysis. Although studies have linked a number of genetic and environmental factors to ALS, the specific causes and mechanisms of the disease are still unclear. The pivotal role of circular RNA in the pathogenesis of ALS is a newly emerging area of research. The term "circular RNA" describes a particular class of RNA molecule that, in contrast to most RNA molecules, has a closed-loop structure. According to recent research, circular RNA might be essential for the development and progression of ALS. It has been discovered that these circular RNAs support important cellular functions related to ALS, including protein turnover, mitochondrial function, RNA processing, and cellular transport. Gaining knowledge about the precise roles and processes of circular RNA in the development of ALS could assist in understanding the pathophysiology of the disease and possibly pave the way for the development of targeted therapies. However, the understanding of circular RNA in ALS is still limited, and more research is needed to fully elucidate its role. In order to gain a comprehensive understanding of the role of circRNAs in ALS, it is imperative to delve into the various mechanisms through which circRNAs may contribute to the development and progression of the disease. Examining the current status of circRNA research in ALS and offering insights into their potential as therapeutic targets and diagnostic markers are the primary objectives of this review.

Long noncoding RNAs and circular RNAs as potential diagnostic biomarkers of inflammatory bowel diseases: a systematic review and meta-analysis

Introduction

Inflammatory bowel disease (IBD) poses a growing global burden, necessitating the discovery of reliable biomarkers for early diagnosis. The clinical significance of dysregulated expression of long noncoding RNAs (lncRNAs) and circular RNAs (circRNAs) in diagnosing IBD has not been well established. Thus, our study aimed to investigate the diagnostic value of lncRNAs and circRNAs for IBD based on currently available studies.

Methods

A comprehensive search was carried out in diverse electronic databases, such as PubMed, Embase, Scopus, Science Direct and Wiley Online Library to retrieve articles published until October 30, 2023. Stata 17.0 software was employed to determine pooled sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic ratio (DOR), and area under the curve (AUC). Heterogeneity, subgroup analysis, and meta-regression were explored, and publication bias was assessed using Deeks' funnel plot. Fagan's nomogram and likelihood ratio scattergram were employed to evaluate the clinical validity.

Result

A total of 11 articles encompassing 21 studies which involved 1239 IBD patients and 985 healthy controls were investigated. The findings revealed lncRNAs exhibit high level of pooled sensitivity 0.94 (95% CI: 0.87-0.97) and specificity 0.99 (95% CI: 0.89-1.00), along with PLR, NLR, DOR, and AUC values of 64.25 (95% CI: 7.39-558.66), 0.06 (95% CI: 0.03-0.13), 1055.25 (95% CI: 70.61-15770.77), and 0.99 (95% CI: 0.97-0.99), respectively. Conversely, CircRNAs showed moderate accuracy in IBD diagnosis, with sensitivity of 0.68 (95% CI: 0.61-0.73), specificity of 0.73 (95% CI: 0.65-0.79), PLR of 2.47 (95% CI: 1.94-3.16), NLR of 0.45 (95% CI: 0.38-0.53), DOR of 5.54 (95% CI: 3.88-7.93), and AUC value of 0.75 (95% CI: 0.71-0.79). Moreover, findings from subgroup analysis depicted heightened diagnostic efficacy when employing lncRNA H19 and a large sample size (≥100), with notable efficacy in diagnosing both ulcerative colitis (UC) and Crohn's disease (CD).

Conclusion

LncRNAs exhibit high diagnostic accuracy in distinguishing patients with IBD from healthy controls signifying their possible use as potential biomarkers, while circRNAs showed moderate diagnostic accuracy. Nevertheless, to validate our findings and confirm the clinical utility of lncRNAs and circRNAs in IBD diagnosis, a large pool of prospective and multi-center studies should be undertaken.

Systematic review registration

https://www.crd.york.ac.uk/PROSPERO, identifier CRD42023491840.

Circ_0001495 influences the development of endometriosis through the miRNA-34c-5p/E2F3 axis

Endometriosis is a chronic gynecological condition characterized by the presence of endometrial glands and stroma outside the uterine cavity., accounting for 7% of all female malignant tumors and 20%- 30% of malignant tumors of the female reproductive system. Multiple studies have shown that circular RNA (circRNA) has the potential to become a targeted target and marker for EM. However, the roles of circ_0001495 in EM are still unclear. Our research aims to reveal the molecular mechanism of circ_0001495 in EM. In this study, RT-PCR or western blot were conducted to determine mRNA and protein expression. cell viability, proliferation, migration, invasion, and apoptosis were assessed by CCK-8, EdU, wound healing, transwell, and flow cytometry analyses, respectively. Additionally, the targeting relationship between miR-34c-5p and circ_0001495 or E2F3 was confirmed through dual-luciferase reporter gene assay. We found significant overexpression of circ_0001495 in EM tissues and cells. Knockdown of circ_0001495 inhibited the proliferation, migration and invasion of ectopic endometrial stromal cells (EESCs) and increased cell apoptosis. Moreover, we found that circ_0001495 regulated E2F3 levels by interacting with miR-34c-5p in EESC. Furthermore, in vitro, miR-34c-5p inhibition or E2F3 overexpression could attenuate the effect of circ_0001495 silencing on EM progression. In addition, the vivo experiment demonstrated that inhibition of circ_0001495 could repress the development of endometriosis by regulating the miR-34c-5p/E2F3 axis. In conclusion, our study suggested that circ_0001495 promoted EM progression in vitro and in vivo through the miR-34c-5p/E2F3 axis, which might be a potential therapeutic target for EM.

miR-30c affects the pathogenesis of ulcerative colitis by regulating target gene VIP

MicroRNAs play a crucial role in regulating the epithelial barrier and immune response, which are implicated in the pathogenesis of ulcerative colitis (UC). This study aimed to investigate the role and molecular mechanism of miR-30c in the pathogenesis of UC using a dextran sulfate sodium salt (DSS)-induced colitis model, which is similar to ulcerative colitis. Wild-type (WT) and miR-30c knockout (KO) mice were assigned to either control or DSS-treated groups to evaluate the influence of aberrant miR-30c expression on UC pathogenesis. The disease activity index, inflammatory factors, and the extent of pathological and histological damage in colon tissues were analyzed. The effect of miR-30c on vasoactive intestinal peptide (VIP) gene expression was validated through luciferase reporter assay, qRT-PCR, Western blotting, and immunohistochemistry. The results showed that miR-30c KO mice with DSS-induced colitis model showed more severe phenotypes: significantly higher disease activity indices, significant body weight loss, reduced length of the colon of mice, increased number of aberrant crypt structures, reduced mucus secretion, and significant differences in inflammatory factors. These findings suggested that the absence of miR-30c might promote DSS-induced colitis, and the targe-regulatory effect of miR-30c on VIP might play an important role in the development of colitis.

A circRNA ceRNA network involved in cognitive dysfunction after chronic cerebral hypoperfusion

Chronic Cerebral Hypoperfusion (CCH) is associated with cognitive dysfunction, the underlying mechanisms of which remain elusive, hindering the development of effective therapeutic approaches. In this study, we employed an established CCH animal model to delve into neuropathological alterations like oxidative stress, inflammation, neurotransmitter synthesis deficits, and other morphological alterations. Our findings revealed that while the number of neurons remained unchanged, there was a significant reduction in neuronal fibers post-CCH, as evidenced by microtubule-associated protein 2 (MAP2) staining. Moreover, myelin basic protein (MBP) staining showed exacerbated demyelination of neuronal fibers. Furthermore, we observed increased neuroinflammation, proliferation, and activation of astrocytes and microglia, as well as synaptic loss and microglial-mediated synapse engulfment post-CCH. Utilizing RNA sequencing, differential expression analysis displayed alterations in both mRNAs and circRNAs. Following gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses, both showed significant enrichment in immunological and inflammation-related terms and pathways. Importantly, the differentially expressed circular RNAs (DE circRNAs) exhibited a notable coexpression pattern with DE mRNAs. The ternary circRNA-miRNA-mRNA competing endogenous RNAs (ceRNA) network was constructed, and subsequent analysis reiterated the significance of neuroimmunological and neuroinflammatory dysfunction in CCH-induced neuropathological changes and cognitive dysfunction. This study underscores the potential role of circRNAs in these processes, suggesting them as promising therapeutic targets to mitigate the detrimental effects of CCH.

Circular RNAs in inflammatory bowel disease

Inflammatory bowel disease (IBD) is a term encompassing a few chronic inflammatory disorders that leads to damage of the intestinal tract. Although much progress has been made in understanding the pathology of IBD, the precise pathogenesis is not completely understood. Circular RNAs (circRNAs) are single-stranded, covalently closed, endogenous molecules in eukaryotes with a variety of biological functions. CircRNAs have been shown to have regulatory effects in many diseases, such as cancer, cardiovascular disease, and neurological disorders. CircRNAs have also been found to play important roles in IBD, and although they are not sufficiently investigated in the context of IBD, a few circRNAs have been identified as potential biomarkers for the diagnosis and prognosis of IBD and as potential therapeutic targets for IBD. Herein, we survey recent progress in understanding the functions and roles of circRNAs in IBD and discuss their potential clinical applications.

Exploring the Multifaceted Biologically Relevant Roles of circRNAs: From Regulation, Translation to Biomarkers

CircRNAs are a category of regulatory RNAs that have garnered significant attention in the field of regulatory RNA research due to their structural stability and tissue-specific expression. Their circular configuration, formed via back-splicing, results in a covalently closed structure that exhibits greater resistance to exonucleases compared to linear RNAs. The distinctive regulation of circRNAs is closely associated with several physiological processes, as well as the advancement of pathophysiological processes in several human diseases. Despite a good understanding of the biogenesis of circular RNA, details of their biological roles are still being explored. With the steady rise in the number of investigations being carried out regarding the involvement of circRNAs in various regulatory pathways, understanding the biological and clinical relevance of circRNA-mediated regulation has become challenging. Given the vast landscape of circRNA research in the development of the heart and vasculature, we evaluated cardiovascular system research as a model to critically review the state-of-the-art understanding of the biologically relevant functions of circRNAs. We conclude the review with a discussion of the limitations of current functional studies and provide potential solutions by which these limitations can be addressed to identify and validate the meaningful and impactful functions of circRNAs in different physiological processes and diseases.

Identification of potentially functional circRNAs and prediction of the circRNA-miRNA-hub gene network in mice with primary blast lung injury

OBJECTIVES

Primary blast lung injury (PBLI) is the main cause of death in blast injury patients, and is often ignored due to the absence of a specific diagnosis. Circular RNAs (circRNAs) are becoming recognized as new regulators of various diseases, but the role of circRNAs in PBLI remain largely unknown. This study aimed to investigate PBLI-related circRNAs and their probable roles as new regulators in PBLI in order to provide new ideas for PBLI diagnosis and treatment.

METHODS

The differentially expressed (DE) circRNA and mRNA profiles were screened by transcriptome high-throughput sequencing and validated by quantitative real-time PCR (qRT-PCR). The GO and KEGG pathway enrichment was used to investigate the potential function of DE mRNAs. The interactions between proteins were analyzed using the STRING database and hub genes were identified using the MCODE plugin. Then, Cytoscape software was used to illustrate the circRNA-miRNA-hub gene network.

RESULTS

A total of 117 circRNAs and 681 mRNAs were aberrantly expressed in PBLI, including 64 up-regulated and 53 down-regulated circRNAs, and 315 up-regulated and 366 down-regulated mRNAs. GO and KEGG analysis revealed that the DE mRNAs might be involved in the TNF signaling pathway and Fanconi anemia pathway. Hub genes, including Cenpf, Ndc80, Cdk1, Aurkb, Ttk, Aspm, Ccnb1, Kif11, Bub1 and Top2a, were obtained using the MCODE plugin. The network consist of 6 circRNAs (chr18:21008725-21020999 + , chr4:44893533-44895989 + , chr4:56899026-56910247-, chr5:123709382-123719528-, chr9:108528589-108544977 + and chr15:93452117-93465245 +), 7 miRNAs (mmu-miR-3058-5p, mmu-miR-3063-5p, mmu-miR-668-5p, mmu-miR-7038-3p, mmu-miR-761, mmu-miR-7673-5p and mmu-miR-9-5p) and 6 mRNAs (Aspm, Aurkb, Bub1, Cdk1, Cenpf and Top2a).

CONCLUSIONS

This study examined a circRNA-miRNA-hub gene regulatory network associated with PBLI and explored the potential functions of circRNAs in the network for the first time. Six circRNAs in the circRNA-miRNA-hub gene regulatory network, including chr18:21008725-21020999 + , chr4:44893533-44895989 + , chr4:56899026-56910247-, chr5:123709382-123719528-, chr9:108528589-108544977 + and chr15:93452117-93465245 + may play an essential role in PBLI.

Hsa_circRNA_103124 upregulation in Crohn's disease promoted macrophage M1 polarization to maintain an inflammatory microenvironment via activation of the AKT2 and TLR4/NF-κB pathways

An accumulating body of research indicates that circular RNAs participate in the pathogenesis of Crohn's disease (CD). Hsa_circRNA_103124, which was upregulated in the peripheral blood mononuclear cells of patients with CD, was reported to inhibit autophagy in our previous studies. However, how hsa_circRNA_103124 participates in CD progression remains unclear. In this study, TLR4 was found to be upregulated in THP1 cells overexpressing hsa_circRNA_103124. Bioinformatic analysis indicated that overexpressed hsa_circRNA_103124 was associated with the PI3K/AKT signaling pathway and TLR4-associated innate immunity in inflammatory bowel disease. Therefore, we inferred a possible role for hsa_circRNA_103124 in macrophage polarization. Hsa_circRNA_103124, AKT2 and TLR4 were significantly upregulated in the PBMCs of patients with CD. Further analysis revealed a positive correlation between hsa_circRNA_103124 and AKT2 (r = 0.8029, p < 0.0001), TLR4 (r = 0.2529, p = 0.0089) and the Crohn's disease activity index (r = 0.4535, p < 0.0001) in patients with CD. Notably, hsa_circRNA_103124 promoted macrophage M1 polarization with increased expression of CD80 and CD86, while it inhibited macrophage M2 polarization with decreased expression of CD206 and CD163. Hsa_circRNA_103124 promoted an inflammatory microenvironment by activating the AKT2 and TLR4/NF-κB signaling pathways in M1 polarized THP1 cells. Nevertheless, hsa-miR-650 reversed the role of hsa_circRNA_103124 in M1 polarization. Hsa_circRNA_103124 promoted the formation of neutrophil extracellular traps and reduced the expression of ZO-1. In summary, the results of this study indicated that hsa_circRNA_103124 promoted macrophage M1 polarization to maintain an inflammatory microenvironment via activation of the TLR4/NF-κB pathway in a hsa-miR-650/AKT2 dependent manner. Hsa_circRNA_103124 could serve as a potential biomarker and a novel therapeutic target in CD progression.

Delta- like ligand 4- expressing macrophages and human diseases: Insights into pathophysiology and therapeutic opportunities

Macrophages are key players in the immune response and have been implicated in various human diseases, including atherosclerosis, cancer, and chronic inflammatory disorders. While numerous studies have delved into the nuances of macrophage behavior in these conditions, there remains a gap in understanding the specific role of Delta-like ligand 4 (Dll4)-expressing macrophages and their overarching implications across these diseases. Among the plethora of factors expressed by macrophages, Dll4 has emerged as a molecule of particular interest. Recent studies have highlighted its unique role in modulating macrophage functions and its potential implications in various diseases. This review seeks to consolidate existing knowledge, address this gap, and present a comprehensive overview of Dll4-expressing macrophages in the context of these disorders and highlight their potential as therapeutic targets. We examined the involvement of Dll4-expressing macrophages in multiple human diseases such as atherosclerosis, cancer and chronic inflammatory diseases, emphasizing their influence on disease progression. We also discussed the challenges, limitations, and emerging research areas in targeting Dll4-expressing macrophages and provide an outlook on potential therapeutic strategies for the treatment of these diseases. By addressing the previously existing research gap, we've provided a roadmap that brings together fragmented insights, paving the way for more holistic research and potentially more effective therapeutic strategies centered on Dll4-expressing macrophages.

Circ_0001666 upregulation promotes intestinal epithelial cell fibrosis in pediatric Crohn's disease via the SRSF1/BMP7 axis

The epithelial-mesenchymal transition (EMT) is closely associated with Crohn's disease (CD) related intestinal fibrosis, a condition whose prevalence is increasing annually among children. Recently, the CD marker gene microarray screening revealed an upregulation of circ_0001666 in the colon tissues of CD patients, but its underlying mechanisms remain unclear. In this study, we explored the molecular mechanism of circ_0001666 in regulating EMT-mediated fibrosis in CD in vitro. The levels of circ_0001666 and EMT-associated proteins were assessed in CD clinical samples, and a CD cell model was established using TGF-β1 to induce human intestinal epithelial cells (HIECs). Additionally, the expression levels of genes and proteins related to EMT and fibrosis were analyzed by quantitative real-time PCR and western blot, cell migration, and invasion were assessed via wound healing assay and transwell, respectively, and RNA pull-down and RNA immunoprecipitation assays were performed to verify the relationship between SRSF1 and BMP7 or circ_0001666. Circ_0001666 was overexpressed in the intestinal mucosal tissues of CD patients and was positively correlated with EMT. Silencing circ_0001666 inhibited the migration, invasion, EMT, and fibrosis of HIECs induced by TGF-β1. Mechanistically, circ_0001666 regulated BMP7 expression by interacting with SRSF1. Furthermore, the effects of inhibiting circ_0001666 on HIECs could be partially reversed by overexpressing SRSF1 or silencing BMP7. Collectively, circ_0001666 regulates TGF-β1-induced HIEC migration, invasion, EMT, and fibrosis. Circ_0001666 also promoted EMT-mediated fibrosis by interacting with SRSF1 to accelerate BMP7 mRNA decay. These findings provide new insights into the pathogenesis of CD and suggest that circ_0001666 might be a potential therapeutic target for CD.

CircRNA hsa_circ_0006859 inhibits the osteogenic differentiation of BMSCs and aggravates osteoporosis by targeting miR-642b-5p/miR-483-3p and upregulating EFNA2/DOCK3

Hsa_circ_0006859 has been found as a possible biomarker for postmenopausal osteoporosis (PMOP) with an effect on the osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs), but the underlying mechanism is unclear. Bioinformatics analysis was used to identify dysregulated RNAs involved in osteoporosis based on public datasets. Function assays were used to determine the functions of hsa_circ_0006859 on cell proliferation and osteogenic differentiation in vitro. It was found that hsa_circ_0006859 was upregulated in OVX mice-derived BMSCs, but lowly expressed during osteogenic differentiation. Overexpressing hsa_circ_0006859 inhibited the cell proliferation and osteogenesis of BMSCs and hFOB 1.19 cells, vice versa. Bilateral ovariectomy (OVX) was used to induce PMOP in mice. The interactions among circ_0006859, miR-642b-5p/miR-483-3p, and EFNA2/DOCK3 were determined using the RIP assay. Silencing circ_0006859 relieved PMOP in mice. Mechanistically, circ_0006859 bound to miR-642b-5p/miR-483-3p directly, while miR-642b-5p and miR-483-3p respectively targeted EFNA2 and DOCK3. Hsa_circ_0006859 downregulated the expression of miR-642b-5p/miR-483-3p to upregulate EFNA2/DOCK3. Additionally, miR-642b-5p/miR-483-3p targeted EFNA2/DOCK3 to inhibit BMSCs osteogenic differentiation and facilitate osteoporosis progression by inactivating the Wnt signaling. In conclusion, hsa_circ_0006859 is involved in PMOP by targeting miR-642b-5p/EFNA2 and miR-483-3p/DOCK3 axes to maintain the Wnt-signaling pathway, which may be a novel possible therapeutic targets and biomarkers for PMOP.

MiRNA-Based Therapies for the Treatment of Inflammatory Bowel Disease: What Are We Still Missing?

Micro-RNAs (miRNAs) are noncoding RNAs usually 24-30 nucleotides long that play a central role in epigenetic mechanisms of inflammatory diseases and cancers. Recently, several studies have assessed the involvement of miRNAs in the pathogenesis of inflammatory bowel disease (IBD) and colitis-associated neoplasia. Particularly, it has been shown that many members of miRNAs family are involved in the pathways of inflammation and fibrogenesis of IBD; therefore, their use as inflammatory and fibrosis biomarkers has been postulated. In light of these results, the role of miRNAs in IBD therapy has been proposed and is currently under investigation with many in vitro and in vivo studies, murine models, and a phase 2a trial. The accumulating data have pushed miRNA-based therapy closer to clinical practice, although many open questions remain. With this systematic review, we discuss the current knowledge about the therapeutic effects of miRNAs mimicking and inhibition, and we explore the new potential targets of miRNA family for the treatment of inflammation and fibrosis in IBD.

Circ_0044411 silencing protects infantile pneumonia from lipopolysaccharide-induced cell injury by sponging miR-141-3p to inhibit CCL16 expression

BACKGROUND

Circular RNA (circRNA) has been found to play an important role in the progression of many diseases, including infantile pneumonia. However, the role of circ_0044411 in infantile pneumonia progression is still unclear.

METHODS

MRC-5 cells were incubated with lipopolysaccharide (LPS) for 12 h to establish the in vitro cellular model for infantile pneumonia. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was used to detect the levels of circ_0044411, miR-141-3p (micoRNA-141-3p) and CCL16 (CC motif chemokine ligand 16). Cell viability and proliferation was assessed by 3-(4, 5-dimethylthiazol-2-y1)-2, 5-diphenyl tetrazolium bromide (MTT) assay and 5-ethynyl-2'-deoxyuridine (EdU) assay. The levels of inflammatory factors IL-1β, IL-6 and TNF-α were determined by enzyme-linked immunosorbent assay kits. Cell apoptosis and caspase-3 activity were detected by flow cytometry analysis and caspase-3 activity assay kit. The target interaction was confirmed by dual-luciferase reporter assay, RNA immunoprecipitation assay and RNA pull-down assay.

RESULTS

Circ_0044411 was highly repressed in the serum of infantile pneumonia patients and LPS-induced MRC-5 cells. Circ_0044411 could promote the cell viability and proliferation, inhibit inflammatory response and apoptosis in LPS-induced MRC-5 cells. Circ_0044411 could serve as a sponge of miR-141-3p, and miR-141-3p could reverse the function of circ_0044411 on LPS-induced MRC-5 cell injury. In addition, miR-141-3p could target CCL16, and miR-141-3p could protect MRC-5 cells from LPS-induced cell injury by targeting CCL16. Furthermore, circ_0044411 sponged miR-141-3p to positively regulate CCL16 expression.

CONCLUSION

Circ_0044411 knockdown promoted cell viability and proliferation, inhibited inflammatory response and apoptosis by regulating miR-141-3p/CCL16 axis, indicating that circ_0044411 might be a potential therapeutic target for IP.

Non-coding RNAs in immunoregulation and autoimmunity: Technological advances and critical limitations

Immune cell function is critically dependent on precise control over transcriptional output from the genome. In this respect, integration of environmental signals that regulate gene expression, specifically by transcription factors, enhancer DNA elements, genome topography and non-coding RNAs (ncRNAs), are key components. The first three have been extensively investigated. Even though non-coding RNAs represent the vast majority of cellular RNA species, this class of RNA remains historically understudied. This is partly because of a lag in technological and bioinformatic innovations specifically capable of identifying and accurately measuring their expression. Nevertheless, recent progress in this domain has enabled a profusion of publications identifying novel sub-types of ncRNAs and studies directly addressing the function of ncRNAs in human health and disease. Many ncRNAs, including circular and enhancer RNAs, have now been demonstrated to play key functions in the regulation of immune cells and to show associations with immune-mediated diseases. Some ncRNAs may function as biomarkers of disease, aiding in diagnostics and in estimating response to treatment, while others may play a direct role in the pathogenesis of disease. Importantly, some are relatively stable and are amenable to therapeutic targeting, for example through gene therapy. Here, we provide an overview of ncRNAs and review technological advances that enable their study and hold substantial promise for the future. We provide context-specific examples by examining the associations of ncRNAs with four prototypical human autoimmune diseases, specifically rheumatoid arthritis, psoriasis, inflammatory bowel disease and multiple sclerosis. We anticipate that the utility and mechanistic roles of these ncRNAs in autoimmunity will be further elucidated in the near future.

CircRNAs regulate the crosstalk between inflammation and tumorigenesis: The bilateral association and molecular mechanisms

Inflammation, a hallmark of cancer, has been associated with tumor progression, transition into malignant phenotype and efficacy of the chemotherapeutic agents in cancer. Chronic inflammation provides a favorable environment for tumorigenesis by inducing immunosuppression, whereas acute inflammation prompts tumor suppression by generating anti-tumor immune responses. Inflammatory factors derived from interstitial cells or tumor cells can stimulate cell proliferation and survival by modulating oncogenes and/or tumor suppressors. Recently, a new class of RNAs, i.e., circular RNAs (circRNAs), has been implicated in inflammatory diseases. Although there are reports on circRNAs imparting functions in inflammatory insults, whether these circularized transcripts hold the potential to regulate inflammation-induced cancer or tumor-related inflammation, and modulate the interactions between tumor microenvironment (TME) and the inflammatory stromal/immune cells, awaits further elucidation. Contextually, the current review describes the molecular association between inflammation and cancer, and spotlights the regulatory mechanisms by which circRNAs can moderate TME in response to inflammatory signals/triggers. We also present comprehensive information about the immune cell(s)-specific expression and functions of the circRNAs in TME, modulation of inflammatory signaling pathways to drive tumorigenesis, and their plausible roles in inflammasomes and tumor development. Moreover, the therapeutic potential of these circRNAs in harnessing inflammatory responses in cancer is also discussed.

Role of circRNA in E3 Modification under Human Disease

Circular RNA (circRNA) is often regarded as a special kind of non-coding RNA, involved in the regulation mechanism of various diseases, such as tumors, neurological diseases, and inflammation. In a broad spectrum of biological processes, the modification of the 76-amino acid ubiquitin protein generates a large number of signals with different cellular results. Each modification may change the result of signal transduction and participate in the occurrence and development of diseases. Studies have found that circRNA-mediated ubiquitination plays an important role in a variety of diseases. This review first introduces the characteristics of circRNA and ubiquitination and summarizes the mechanism of circRNA in the regulation of ubiquitination in various diseases. It is hoped that the emergence of circRNA-mediated ubiquitination can broaden the diagnosis and prognosis of the disease.

Oral zero-valent-molybdenum nanodots for inflammatory bowel disease therapy

Inflammatory bowel disease (IBD) affects millions of people each year. The overproduction of reactive oxygen species (ROS) plays a critical role in the progress of IBD and will be a potential therapeutic target. Here, we synthesize a kind of oral zero-valent-molybdenum nanodots (ZVMNs) for the treatment of IBD by scavenging ROS. These ultrasmall ZVMNs can successfully pass through the gastric acid and then be absorbed by the intestine. It has been verified that ZVMNs can down-regulate the quantity of ROS and reduce colitis in a mouse IBD model without distinct side effects. In addition, RNA sequencing reveals a further mechanism that the ZVMNs can protect colon tissues from oxidative stress by inhibiting the nuclear factor κB signaling pathway and reducing the production of excessive pro-inflammatory factors. Together, the ZVMNs will offer a promising alternative treatment option for patients suffering from IBD.

PLGA-microspheres-carried circGMCL1 protects against Crohn's colitis through alleviating NLRP3 inflammasome-induced pyroptosis by promoting autophagy

This study aimed to at explore exploring the biological functions of dysregulated circRNA in Crohn's disease (CD) pathogenesis, with the overarching goal of and providing potential novel therapeutic targets. CircRNA microarray and quantitative real time-polymerase chain reaction (qRT-PCR) analyses were performed to investigate and verify the candidate dysregulated circRNA. The Next, clinical, in vivo, and in vitro studies were performed to investigate explore the biological function and mechanisms of the candidate circRNA in CD. The therapeutic effect of poly (lactic-co-glycolic acid)-microspheres (PLGA MSs)-carried oe-circGMCL1 in experimental colitis models of IL-10 knock-out mice was assessed. CircGMCL1 was identified as the candidate circRNA by microarray and qRT-PCR analyses. Results showed that circGMCL1 expression was negatively correlated with CD-associated inflammatory indices, suggesting that it is a CD-associated circRNA. Microarray and bioinformatics analyses identified miR-124-3p and Annexin 7 (ANXA7) as its downstream mechanisms. The in vitro studies revealed that circGMCL1 mediates its effects on autophagy and NLRP3 inflammasome-mediated pyroptosis in epithelial cells through the ceRNA network. Moreover, the in vivo studies identified the therapeutic effect of PLGA MSs-carried oe-circGMCL1 in experimental colitis models. This study suggests that circGMCL1 protects intestinal barrier function against Crohn's colitis through alleviating NLRP3 inflammasome-mediated epithelial pyroptosis by promoting autophagy through regulating ANXA7 via sponging miR-124-3p. Therefore, circGMCL1 can serve as a potential biological therapeutic target for Crohn's colitis.

CircEXOC5 facilitates cell pyroptosis via epigenetic suppression of Nrf2 in septic acute lung injury

Acute lung injury (ALI) caused by sepsis is characterized by a destructive high inflammatory response in lungs, which is the ultimate cause of high mortality to patients diagnosed with sepsis. The objective of the present study is to explore the effect and related mechanisms of circEXOC5 on pyroptosis in septic ALI. Sepsis ALI mouse model was induced and established by CLP induction and sepsis MPVEC cell model by LPS. HE staining was used to detect lung tissue pathological changes. ELISA, flow cytometry, and Western blot were utilized to evaluate the release of inflammatory cytokines and cell pyroptosis, and RIP was applied to verify the binding relationship between EZH2 and circEXOC5 or Nrf2. Finally, the interaction between CircEXOC5 and EZH2, H3k27me3, and Nrf2 promoter regions was clarified using ChIP. CircEXOC5 levels were notably ascended in the lung tissues of septic ALI mice. And silencing circEXOC5 inhibited cell pyroptosis and the release of inflammatory cytokines in MPVEC stimulated by LPS. In addition, RIP and ChIP indicated that Nrf2 expression in MPVECs cells could be inhibited by circEXOC5 via recruiting EZH2. In addition, ML385 (a specific inhibitor of Nrf2) reversed the efficacy of Knockdown of circEXOC5 on the Inhibition of pyroptosis and inflammation of MPVEC cells stimulated by LPS. These results indicated that CircEXOC5 could promote cell pyroptosis through epigenetic inhibition of Nrf2 in septic ALI.

Impact of the Exposome on the Epigenome in Inflammatory Bowel Disease Patients and Animal Models

Inflammatory bowel diseases (IBD) are chronic inflammatory disorders of the gastrointestinal tract that encompass two main phenotypes, namely Crohn’s disease and ulcerative colitis. These conditions occur in genetically predisposed individuals in response to environmental factors. Epigenetics, acting by DNA methylation, post-translational histones modifications or by non-coding RNAs, could explain how the exposome (or all environmental influences over the life course, from conception to death) could influence the gene expression to contribute to intestinal inflammation. We performed a scoping search using Medline to identify all the elements of the exposome that may play a role in intestinal inflammation through epigenetic modifications, as well as the underlying mechanisms. The environmental factors epigenetically influencing the occurrence of intestinal inflammation are the maternal lifestyle (mainly diet, the occurrence of infection during pregnancy and smoking); breastfeeding; microbiota; diet (including a low-fiber diet, high-fat diet and deficiency in micronutrients); smoking habits, vitamin D and drugs (e.g., IBD treatments, antibiotics and probiotics). Influenced by both microbiota and diet, short-chain fatty acids are gut microbiota-derived metabolites resulting from the anaerobic fermentation of non-digestible dietary fibers, playing an epigenetically mediated role in the integrity of the epithelial barrier and in the defense against invading microorganisms. Although the impact of some environmental factors has been identified, the exposome-induced epimutations in IBD remain a largely underexplored field. How these environmental exposures induce epigenetic modifications (in terms of duration, frequency and the timing at which they occur) and how other environmental factors associated with IBD modulate epigenetics deserve to be further investigated.

Circ_0066881 targets miR-144-5p/RORA axis to alleviate LPS-induced apoptotic and inflammatory damages in human periodontal ligament cells

Circular RNAs (circRNAs) are involved in the regulation of various diseases, including periodontitis. The objective of this study was to analyze the biological role and regulatory mechanism of circ_0066881 in LPS-induced periodontal ligament cells (PDLCs). Circ_0066881, microRNA-144-5p (miR-144-5p) and retinoid acid-related orphan receptor A (RORA) levels were determined using reverse transcription-quantitative PCR (RT-qPCR) assay. Cell viability detection was performed by Cell Counting Kit-8 assay. Cell apoptosis was assessed through flow cytometry and caspase-3 activity assay. The protein analysis was completed via Western blot. Inflammatory cytokines were measured by ELISA. The target interaction was validated by dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay. The level of circ_0066881 was down-regulated in periodontitis tissues. Overexpression of circ_0066881 relieved LPS-induced cell viability inhibition and apoptosis or inflammation promotion in PDLCs. Circ_0066881 could bind to miR-144-5p. The protective function of circ_0066881 was achieved by sponging miR-144-5p in PDLCs. Circ_0066881 acts as a miR-144-5p sponge to mediate the RORA level. Inhibition of miR-144-5p attenuated LPS-induced cell injury via targeting RORA. All these results demonstrated that circ_0066881 partly prevented LPS-evoked cell dysfunction in PDLCs through miR-144-5p-mediated up-regulation of RORA.

iGRLCDA: identifying circRNA-disease association based on graph representation learning

While the technologies of ribonucleic acid-sequence (RNA-seq) and transcript assembly analysis have continued to improve, a novel topology of RNA transcript was uncovered in the last decade and is called circular RNA (circRNA). Recently, researchers have revealed that they compete with messenger RNA (mRNA) and long noncoding for combining with microRNA in gene regulation. Therefore, circRNA was assumed to be associated with complex disease and discovering the relationship between them would contribute to medical research. However, the work of identifying the association between circRNA and disease in vitro takes a long time and usually without direction. During these years, more and more associations were verified by experiments. Hence, we proposed a computational method named identifying circRNA-disease association based on graph representation learning (iGRLCDA) for the prediction of the potential association of circRNA and disease, which utilized a deep learning model of graph convolution network (GCN) and graph factorization (GF). In detail, iGRLCDA first derived the hidden feature of known associations between circRNA and disease using the Gaussian interaction profile (GIP) kernel combined with disease semantic information to form a numeric descriptor. After that, it further used the deep learning model of GCN and GF to extract hidden features from the descriptor. Finally, the random forest classifier is introduced to identify the potential circRNA-disease association. The five-fold cross-validation of iGRLCDA shows strong competitiveness in comparison with other excellent prediction models at the gold standard data and achieved an average area under the receiver operating characteristic curve of 0.9289 and an area under the precision-recall curve of 0.9377. On reviewing the prediction results from the relevant literature, 22 of the top 30 predicted circRNA-disease associations were noted in recent published papers. These exceptional results make us believe that iGRLCDA can provide reliable circRNA-disease associations for medical research and reduce the blindness of wet-lab experiments.

New Insights and Advances in Pathogenesis and Treatment of Very Early Onset Inflammatory Bowel Disease

Very early onset inflammatory bowel disease (VEO-IBD) is characterized by multifactorial chronic recurrent intestinal inflammation. Compared with elderly patients, those with VEO-IBD have a more serious condition, not responsive to conventional treatments, with a poor prognosis. Recent studies found that genetic and immunologic abnormalities are closely related to VEO-IBD. Intestinal immune homeostasis monogenic defects (IIHMDs) are changed through various mechanisms. Recent studies have also revealed that abnormalities in genes and immune molecular mechanisms are closely related to VEO-IBD. IIHMDs change through various mechanisms. Epigenetic factors can mediate the interaction between the environment and genome, and genetic factors and immune molecules may be involved in the pathogenesis of the environment and gut microbiota. These discoveries will provide new directions and ideas for the treatment of VEO-IBD.

Construction of ceRNA Network to Reveal Potential Biomarkers in Crohn's Disease and Validation in a TNBS Induced Mice Model

Purpose

We aimed to construct a competing endogenous RNA (ceRNA) network and explore the potential biomarkers in Crohn's disease (CD) via bioinformatics analysis. Validation of candidate biomarkers in a 2,4,6-trinitrobenzene sulfonic acid (TNBS) induced experimental colitis model and ceRNA network in an HCT116 cell line was also an aim, along with purposing to reveal the pathogenesis of CD.

Methods

GSE102134 and GSE67106 datasets were obtained and used to screen the differentially expressed genes. WCGNA was applied to identify the relative model to construct the ceRNA network. Furthermore, the relationship between candidate gene and immune infiltration was investigated. Then, the expression of potential biomarkers was validated via qRT-PCR in a TNBS induced experimental colitis model. Finally, the ceRNA network was confirmed by RNAi experiments in an HCT116 cell line.

Results

The ceRNA network, consisting of four lncRNAs, four miRNAs, and eight mRNAs, was constructed and the ROC analysis showed four mRNAs (PTGS2, LPL, STAT1, and TRIB2) had high diagnostic accuracy (AUC>0.9). In addition, upregulated PTGS2 was positively correlated with immune cell infiltration, including Natural killer cells, exhausted T-cells, monocytes, and Dendritic cells. The outcome of this TNBS induced experimental colitis model verified that the expression of PTGS2 and mir-429 was consistent with results of previous bioinformatics analysis. Furthermore, the predicted ceRNA network MIR3142HG/mir-429/PTGS2 were validated via RNA interference. Knockout of MIR3142HG decreased the mRNA level of PTGS2, whereas inhibition of mir-429 increased the mRNA level of PTGS2 in the HCT116 cell line.

Conclusion

The exploration of the ceRNA network in this work might contribute to understanding the pathogenesis of CD. The constructed MIR3142HG/mir-429/PTGS2 ceRNA network may play a role in CD, and PTGS2 can be a potential immune-related biomarker in CD.