Isolation and profiling of plasma microRNAs: Biomarkers for asthma and allergic rhinitis.

Chronic inflammatory diseases can be particularly challenging to diagnose and characterize, as inflammatory changes in tissue may not be present in blood. There is a crucial need to develop non-invasive biomarkers that would be useful in diagnosing disease and selecting medical therapies. For example, there are no blood tests to diagnose asthma, a common inflammatory lung disease. MicroRNA (miRNA) expression profiling in blood is emerging as a potentially sensitive and useful biomarker of many diseases. In particular, we have characterized a cost-effective PCR-based array technology to measure and profile circulating miRNAs in the plasma of patients with allergic rhinitis and asthma. Here, we describe the methods to isolate, quantify, and analyze miRNAs in the plasma of human subjects as well as ways to determine their diagnostic utility.

Mannose receptor modulates macrophage polarization and allergic inflammation through miR-511-3p.

BACKGROUND: Mannose receptor (MRC1/CD206) has been suggested to mediate allergic sensitization and asthma to multiple glycoallergens, including cockroach allergens. OBJECTIVE: We sought to determine the existence of a protective mechanism through which MRC1 limits allergic inflammation through its intronic miR-511-3p. METHODS: We examined MRC1-mediated cockroach allergen uptake by lung macrophages and lung inflammation using C57BL/6 wild-type (WT) and Mrc1-/- mice. The role of miR-511-3p in macrophage polarization and cockroach allergen-induced lung inflammation in mice transfected with adeno-associated virus (AAV)-miR-511-3p (AAV-cytomegalovirus-miR-511-3p-enhanced green fluorescent protein) was analyzed. Gene profiling of macrophages with or without miR-511-3p overexpression was also performed. RESULTS: Mrc1-/- lung macrophages showed a significant reduction in cockroach allergen uptake compared with WT mice, and Mrc1-/- mice had an exacerbated lung inflammation with increased levels of cockroach allergen-specific IgE and TH2/TH17 cytokines in a cockroach allergen-induced mouse model compared with WT mice. Macrophages from Mrc1-/- mice showed significantly reduced levels of miR-511-3 and an M1 phenotype, whereas overexpression of miR-511-3p rendered macrophages to exhibit a M2 phenotype. Furthermore, mice transfected with AAV-miR-511-3p showed a significant reduction in cockroach allergen-induced inflammation. Profiling of macrophages with or without miR-511-3p overexpression identified 729 differentially expressed genes, wherein expression of prostaglandin D2 synthase (Ptgds) and its product PGD2 were significantly downregulated by miR-511-3p. Ptgds showed a robust binding to miR-511-3p, which might contribute to the protective effect of miR-511-3p. Plasma levels of miR-511-3p were significantly lower in human asthmatic patients compared with nonasthmatic subjects. CONCLUSION: These studies support a critical but previously unrecognized role of MRC1 and miR-511-3p in protection against allergen-induced lung inflammation.

Effects of allergic stimulation and glucocorticoids on miR-155 in CD4+ T-cells.

RATIONALE: MicroRNAs (miRNAs) are emerging as important regulators of allergic inflammation and potential therapeutic targets. We sought to identify which miRNAs are expressed in CD4+ T-cells and determine whether allergic stimuli or glucocorticoids alter their expression. METHODS: After IRB approval, blood was collected from dust mite (DM) allergic rhinitis subjects (n=20), non-allergic controls (n=8), and asthmatics (n=16). Peripheral blood mononuclear cells were incubated with dust mite extract (DME), diluent control, or DME + dexamethasone (0.1 µM). CD4+ T-cells were collected by magnetic bead column, and RNA was isolated by guanidinium/phenol-chloroform extraction. MicroRNA expression was measured using Nanostring microarray and quantitative real time PCR (qPCR). RESULTS: We identified 196 miRNAs that were stably expressed in circulating CD4+ T-cells. Allergen stimulation of CD4+ T-cells with DME differentially induced miR-155 expression in cells of DM-allergic subjects as compared to non-allergic subjects. Induction of miR-155 expression was also observed with anti-CD3/anti-CD28 simulation and phorbol-12-Myristate-13-Acetate (PMA) treatment, and further augmented by calcium inophore and bromocyclic AMP in the latter treatment. The level of miR-155 expression was positively associated with expression of the TH2 cytokines IL-5 and IL-13. Inhibition of miR-155 in Jurkat T-cells inhibited the production of these cytokines. Glucocorticoids attenuated the effects of dust mite allergen, raising the possibility that inhibition of this miRNA could be a mechanism through which glucocorticoids exhibit their anti-inflammatory effects. The CD4+ T-cells had a higher level of miR-155 expression in asthma compared to in allergic rhinitis and non-asthmatics. The inhibitory effects of glucocorticoids on CD4+ T-cell miR-155 expression were lost in severe asthmatics. CONCLUSION: Mir-155 is differentially expressed in allergic T-cells exposed to DM extract compared to in non-allergic cells and it is inhibited by glucocorticoids. MiR-155 may play a role in mediating allergic inflammation in T-cells and could be an anti-inflammatory target of steroids. This pathway may be de-regulated in severe asthma.