Long non-coding RNA MALAT1 sponges miR-149 to promote inflammatory responses of LPS-induced acute lung injury by targeting MyD88.

Acute lung injury (ALI) caused by sepsis occurs early and the condition is severe, and is also an important reason for accelerating the death of patients. Increasing evidence has identified long non-coding RNA (lncRNA) metastasis associated in lung adenocarcinoma transcript 1 (MALAT1) as a regulator of ALI. However, the potential mechanism underlying MALAT1 on ALI still needs further identification. To explore the mechanisms of gene regulation expression mediated by MALAT1 through miR-149/MyD88 in lung injury inflammation, we constructed a lung injury inflammatory model using the lipopolysaccharides (LPS)-induced method and quantificated the cytokines and signaling cascade molecules as well as miR-149. The MALAT1, myeloid differentiation factor 88 (MyD88), tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and IL-6 levels were significantly increased, and the nuclear factor-κB (NF-κB) pathway was activated, but the miR-149 level was decreased in the LPS-induced ALI model. miR-149 directly targeted both lncRNA MALAT1 and the MyD88 gene. Knockdown of MALAT1 down-regulated the levels of MyD88, TNF-α, IL-1β, and IL-6, and inhibited the NF-κB pathway. However, MALAT1 knockdown up-regulated the expression of miR-149. Overexpression of miR-149 down-regulated MyD88, TNF-α, IL-1β, and IL-6 levels, and inhibited the NF-κB pathway. MALAT1 acts as a pro-inflammatory factor in ALI via the miR-149/MyD88/NF-κB axis and is therefore a potential novel therapeutic target for ALI treatment.