Long non-coding RNA growth arrest specific-5: a potential biomarker for early diagnosis of severe asthma.

BACKGROUND

The diagnosis of severe asthma (SA) is difficult due to a necessary long-term treatment history currently, while there are few studies on biomarkers in the diagnosis of SA. Long non-coding RNA (lncRNA) growth arrest specific-5 (GAS5) has the potential of playing this role because its binding with glucocorticoid receptor (GR). The purpose of this article is to explore the possibility of lncRNA GAS5 acting as a biomarker for early diagnosis of severe asthma (SA).

METHODS

Peripheral blood was obtained from healthy volunteers, patients with non-severe asthma (nSA) and SA, and peripheral blood mononuclear cells (PBMCs) were separated. Twenty-four female BALB/c mice (aged 6 weeks) were randomly and averagely divided into 3 groups, i.e., control group, asthma group and dexamethasone group. The mice were sensitized and challenged with ovalbumin (OVA) and lipopolysaccharide (LPS) to establish a murine model of steroid-insensitive asthma. Human bronchial epithelial cells (HBECs) were cultured, transfected with miR-9 mimics, JNK1 inhibitor and treated with interleukin (IL)-2 + IL-4 and dexamethasone. Western blot was used to detect glucocorticoid receptor phosphorylation at serine 226 (GR), and quantitative real-time PCR was used to detect GAS5 level.

RESULTS

The level of GAS5 in PBMCs from nSA group elevated 20-fold higher after dexamethasone treatment , while it reduced 15-fold lower in SA group (P<0.001). The expression of GR in PBMCs from SA group was significantly higher than that from control group and nSA group after dexamethasone treatment (P<0.001). In the lung tissue of mice, the GAS5 level of dexamethasone group was lower than that of asthma group (P<0.001) and control group (P<0.05). Both treatment with IL-2 + IL-4 and transfection of miR-9 mimics could increase the expression of GR in HBECs (P<0.001). The GAS5 level in HBECs after IL-2 + IL-4 + Dexamethasone treatment was lower than that in HBECs only treated with IL-2 + IL-4 (P<0.001). Similarly, dexamethasone treatment also decreased the level of GAS5 in HBECs transfected with miR-9 mimics (P<0.05). Moreover, transfecting with JNK1 inhibitor could reverse the expression of GAS5 in HBECs transfected with miR-9 mimics and treated with dexamethasone. However, the level of GAS5 in HBECs interfered with IL-2 + IL-4 + Dexamethasone was not affected by JNK1 inhibitor.

CONCLUSIONS

The expression of GAS5 is different in PBMCs between nSA and SA, and is affected by glucocorticoids treatment, which is due to GR phosphorylation. GAS5 can be used as a potential biomarker for diagnosis of severe asthma by comparing GAS5 level in PBMCs from patients before and after glucocorticoids treatment .