Down-regulation of KLF9 ameliorates LPS-caused acute lung injury and inflammation in mice via reducing GSDMD expression

Abstract

Acute lung injury (ALI) is considered as a severe respiratory disease with aggravated inflammatory responses. Krüppel-like factor 9 (KLF9), a member of KLF family, has been reported to be involved in inflammatory disorders. However, the effect of KLF9 in ALI has not been elucidated. Here the present study was to clarify the role of KLF9 and its mechanism in ALI. The ALI in vitro model was established with lipopolysaccharide (LPS)-treated RAW264.7 cells. Mice were injected with LPS to conduct an ALI in vivo model. The expression of KLF9 and gasdermin D (GSDMD) was examined using quantitative reverse transcription-PCR, haematoxylin-eosin/immunohistochemistry staining and western blot assays. Enzyme-linked immunosorbent assay was employed to detect the levels of inflammatory cytokines. JASPAR database was used to predict the recognition motif of KLF9, and the relationship between KLF9 and GSDMD was determined by luciferase reporter assay and chromatin immunoprecipitation analysis. The number of neutrophils in bronchoalveolar lavage fluid as well as the wet/dry weight ratio was caculated. The results showed that The expression of KLF9 in lung was significantly increased in LPS-stimulated mice. Moreover, KLF9 knockout relieved the lung injury in ALI mice. GSDMD is one of targets genes of the transcription factor KLF9. KLF9 knockout induced a decreased expression of GSDMD in LPS-treated mice. Furthermore, in RAW264.7 cells after LPS administration, KLF9 knockdown reduced the levels of inflammatory factors and suppressed the expression of GSDMD. In summarise, these findings exhibited that KLF9 knockout could mitigate the lung injury and inflammatory responses in ALI mice by directly regulating GSDMD.

Keywords:

• KLF9
• acute lung injury
• GSDMD
• LPS
• transcription factor

Data availability statement

The datasets used and analysed during the current study are available from the corresponding author on reasonable request.

Disclosure statement

The authors declare that they have no competing interests.

Ethics approval and consent to participate

The experimental protocol of our study was performed in accordance with the Guide for the Care and Use of Laboratory Animals and approved by Yantaishan Hospital.

Funding

The author(s) reported there is no funding associated with the work featured in this article.