Objective To detect the expression of microRNA (miR)-98-5p and long non-coding RNA (LncRNA) X inactive specific transcript (XIST) in serum of children with acute respiratory distress syndrome (ARDS), and to explore the relationship between miR-98-5p and LncRNA XIST and disease severity and prognosis.

Methods A total of 86 children with ARDS were selected as study sujects (study group).During the same period, 90 healthy children were set as controls (control group).Children with ARDS were divided into mild, moderate and severe groups according to the arterial partial pressure of oxygen/inspired oxygen concentration in the Berlin (2012) diagnostic criteria for the severity of ARDS.In addition, children with ARDS were divided into the survival group and death group according to their 28-day survival status.Serum levels of miR-98-5p and LncRNA XIST were detected by real-time PCR (RT-PCR).Receiver operating characteristic (ROC) curves were drawn to analyze the predictive value of serum miR-98-5p and LncRNA XIST levels for the poor prognosis in children with ARDS.Kaplan-Meier survival curve was used to analyze the relationship between the serum levels of miR-98-5p and LncRNA XIST and the prognosis of children with ARDS; Pearson analysis was performed to analyze the correlation between miR-98-5p and LncRNA XIST in serum of children with ARDS.

Results Compared with the control group, the serum level of miR-98-5p in the study group decreased (P < 0.01), and the level of LncRNA XIST increased (P < 0.01).Compared with the mild group, the serum level of miR-98-5p in the moderate and severe groups decreased (P < 0.05), and the level of LncRNA XIST increased (P < 0.05);compared with the moderate group, the serum level of miR-98-5p in the severe group decreased (P < 0.05), and the level of LncRNA XIST increased (P < 0.05).Compared with the survival group, the serum level of miR-98-5p in the death group decreased (P < 0.01), and the level of LncRNA XIST increased (P < 0.01).The ROC curve showed that the area under the ROC curve of serum miR-98-5p and LncRNA XIST levels in predicting poor prognosis in children with ARDS were 0.771 and 0.764, respectively.The cut-off values were 0.54 and 1.97, respectively, the sensitivity was 76.1% and 86.9%, respectively, and the specificity was 73.7% and 52.6%, respectively; the area under the ROC curve of serum miR-98-5p combined with LncRNA XIST for predicting poor prognosis in children with ARDS was 0.888 with a sensitivity of 77.6% and a specificity of 94.7%.The survival rate in the high expression group of miR-98-5p was 35.14%, which was higher than that in the low expression group of 12.24% (P < 0.05), and the survival rate of high expression of LncRNA XIST was 12.73%, which was lower than that in the low expression group of 38.71% (P < 0.01).Pearson analysis showed that serum miR-98-5p was negatively correlated with LncRNA XIST in children with ARDS (r=-0.411, P < 0.05).Starbase3.0 predicted that LncRNA XIST had a binding site with miR-98-5p.

Conclusions The level of miR-98-5p in the serum of children with ARDS is decreased and the level of LncRNA XIST is increased, both are closely related to the severity and prognosis of the disease.They are significantly negatively correlated, which are expected to be used to evaluate the severity and prognosis of ARDS.