MiR-375 is downregulated in epithelial cells after IL-13 stimulation and regulates an IL-13-induced epithelial transcriptome

MicroRNAs: Essential players in the regulation of inflammation

Regulation of inflammatory responses is ensured by coordinated control of gene expression in participating immune system and tissue cells. One group of gene expression regulators, the functions of which have recently been started to be uncovered in relation to any type of inflammatory condition, is a class of short single-stranded RNA molecules termed microRNAs (miRNAs). miRNAs function together with partner proteins and mainly cause gene silencing through degradation of target mRNAs or inhibition of translation. A particular miRNA can have hundreds of target genes, and thereby miRNAs together influence the expression of a large proportion of proteins. The role of miRNAs in the immune system has been extensively studied since the discovery of miRNAs in mammalian cells approximately 10 years ago. The purpose of the current review is to provide an overview on the functions of miRNAs in the regulation of inflammation, with a specific focus on the mechanisms of allergic inflammation. Because recent studies clearly demonstrate the presence of extracellular miRNAs in body fluids and propose the involvement of miRNAs in cell-cell communication, we will also highlight findings about functions of extracellular miRNAs. The possible use of miRNAs as biomarkers, as well as miRNA-related novel treatment modalities, might open a new future for the diagnosis and treatment of many inflammatory conditions, including allergic diseases.

Biomarkers for eosinophilic esophagitis: a review

BACKGROUND

The complex pathophysiology of eosinophilic esophagitis (EoE) provides several candidate biomarkers that could be used to establish diagnosis, assess response to therapy, and document disease recurrence.

OBJECTIVE

To review the literature on various biomarkers of EoE, with respect to their correlation to disease activity and response to treatment.

DATA SOURCES

A literature search was performed using PubMed and OVID with keyword combinations of EoE and various potential biomarkers.

STUDY SELECTIONS

Between 2006 and 2012, 26 studies that investigated the correlation of various tissue and serum biomarkers with EoE were identified.

RESULTS

The markers investigated included eotaxins-1,-2, and -3, interleukin-5 (IL-5), interleukin-13 (IL-13), eosinophil-derived neurotoxin, mast cell markers, absolute eosinophil count, and micro-RNAs. Several studies have shown a positive correlation between eotaxin-3, IL-5, and IL-13 messenger RNA (mRNA) expression in esophageal tissue and disease activity. Eotaxin-3 mRNA staining was found to have 89% sensitivity for diagnosing EoE. Staining for mast cells and their products has also shown promise. More recently, a microRNA signature that can potentially distinguish EoE from non-EoE esophagitis has been identified.

CONCLUSION

The studies are quite heterogeneous with respect to their methodology and the biomarker(s) studied, but most have investigated tissue biomarkers. Eotaxin-3 and IL-13 have emerged as the most promising ones with respect to sensitivity and degree of positive correlation to disease process. Future research on biomarkers for EoE should include longitudinal studies, establishment of normal values, effects of concomitant atopic diseases, age and gender, and validation of methodology of the tests.