Long noncoding RNAs: novel links to inflammatory bowel disease?

Neutrophil-derived long noncoding RNA IL-7R predicts development of multiple organ dysfunction syndrome in patients with trauma

PURPOSE

Overactive neutrophils are thought to be key drivers in the development of post-traumatic multiple organ dysfunction syndrome (MODS). Little is known about the role of inflammation-related lnc-IL7R in trauma. Thus, we aimed to explore the association between neutrophil-derived lnc-IL7R and post-traumatic MODS.

METHODS

Total RNA was extracted from the isolated circulating neutrophils in 60 patients with trauma and 33 healthy volunteers for lnc-IL7R expression determination by real-time PCR. The correlation of lnc-IL7R expression with disease severity and the development of post-traumatic MODS was analyzed.

RESULTS

The lnc-IL7R levels were significantly lower in trauma patients, especially in those with severe trauma [Injury Severity Score (ISS) ≥ 16], and correlated negatively with the ISS, Acute Physiology and Chronic Health Evaluation II score, and length of ICU stay. The lnc-IL7R levels were also significantly decreased in patients who developed MODS than in those who did not. Lnc-IL7R was an independent predictor of MODS [odds ratio (OR) 0.654, (0.435-0.982), p = 0.041]. The area under the curve for predicting post-traumatic MODS was 0.799 (sensitivity 76.9%, specificity 71.4%), with a cutoff value of 0.024.

CONCLUSIONS

Neutrophil-derived lnc-IL7R is an independent predictor of post-traumatic MODS; therefore, it could be a useful predictive marker for MODS.

The emerging role of lncRNAs in inflammatory bowel disease

Dysregulation of long noncoding RNA (lncRNA) expression is linked to the development of various diseases. Recently, an emerging body of evidence has indicated that lncRNAs play important roles in the pathogenesis of inflammatory bowel diseases (IBDs), including Crohn’s disease (CD) and ulcerative Colitis (UC). In IBD, lncRNAs have been shown to be involved in diverse processes, including the regulation of intestinal epithelial cell apoptosis, association with lipid metabolism, and cell–cell interactions, thereby enhancing inflammation and the functional regulation of regulatory T cells. In this review, we aim to summarize the current knowledge regarding the role of lncRNAs in IBD and highlight potential avenues for future investigation. We also collate potentially immune-relevant, IBD-associated lncRNAs identified through a built-by association analysis with respect to their neighboring protein-coding genes within IBD-susceptible loci. We further underscore their importance by highlighting their enrichment for various aspects of immune system regulation, including antigen processing/presentation, immune cell proliferation and differentiation, and chronic inflammatory responses. Finally, we summarize the potential of lncRNAs as diagnostic biomarkers in IBD.

Studying long noncoding RNAs (lncRNAs) may improve diagnosis and treatment of inflammatory bowel disease (IBD). These RNAs are found between genes in DNA regions previously thought to be “junk,” and have recently been shown to be important in development of various diseases. IBD, which includes both Crohn’s disease and ulcerative colitis, damages the digestive tract lining, causing pain and chronic diarrhea. A better understanding of IBD’s complex causes is needed to identify more effective treatments. Flemming Pociot at the Steno Diabetes Center in Gentofte, Denmark, and co-workers reviewed recent research linking lncRNAs and IBD. They discuss how lncRNAs’ roles in immunity and inflammation influence IBD development, describing how particular lncRNAs are related to IBD. Promising avenues for further research are highlighted, including the use of lncRNAs as biomarkers of IBD, which can be difficult to diagnose.

Roseburia intestinalis-derived flagellin is a negative regulator of intestinal inflammation

Our previous study showed that the Roseburia intestinalis (R. intestinalis), one of the dominant intestinal bacterial microbiota, was significantly decreased in Crohn's disease patients and protected colon epithelial cells from inflammatory damage. However, the roles of lncRNAs in R. intestinalis flagellin-mediated anti-inflammation remain unclear. In this study, we investigate global lncRNA expression profiles using microarray analysis of ulcerative colitis samples from DSS/Flagellin-challenged mice and identified a Flagellin-induced upregulated lncRNA (HIF1A-AS2). Flagellin induced HIF1A-AS2 expression in a dose- and time-dependent manner via p38-stat1 activation. Selective pharmacological inhibitors of Stat1 and p38, and genetic knockdown of these genes abolished Flagellin-induced HIF1A-AS2 expression. In addition, luciferase reporter assay showed that Flagellin activated HIF1A-AS2 promotor via increasing stat1 phosphorylation. Silencing of HIF1A-AS2 abolished Flagellin-mediated anti-inflammatory effects, evaluating by upregulation of cytokines expression, including TNF-α, IL-1β, IL-6 and IL-12, but not TNFβ. In addition, knockdown of HIF1A-AS2 significantly increased p65 and Jnk phosphorylation, and sufficiently abolished Flagellin-mediated anti-inflammatory affects in vivo. Our study provides new insights into the mechanisms that lncRNAs regulate flagellin-mediated alleviation of colonic inflammation. It is indicated that HIF1A-AS2 may be a modulator of intestinal inflammation and represent a novel target for future therapeutics.

The NF-κB-Responsive Long Noncoding RNA FIRRE Regulates Posttranscriptional Regulation of Inflammatory Gene Expression through Interacting with hnRNPU

Long noncoding RNAs, a newly identified class of noncoding RNAs, are important regulators of gene expression in innate immunity. We report in this study that the transcription of FIRRE, a conserved long noncoding RNA between humans and mice, is controlled by NF-κB signaling in macrophages and intestinal epithelial cells. Functionally, FIRRE appears to positively regulate the expression of several inflammatory genes in macrophages or intestinal epithelial cells in response to LPS stimulation via posttranscriptional mechanisms. Specifically, FIRRE physically interacts with heterogeneous nuclear ribonucleoproteins U, regulating the stability of mRNAs of selected inflammatory genes through targeting the AU-rich elements of their mRNAs in cells following LPS stimulation. Therefore, our data indicate a new regulatory role for NF-κB-responsive FIRRE in the posttranscriptional regulation of inflammatory genes in the innate immune system.