LL37-mtDNA regulates viability, apoptosis, inflammation, and autophagy in lipopolysaccharide-treated RLE-6TN cells by targeting Hsp90aa1

Abstract

Sepsis-induced acute lung injury is associated with lung epithelial cell injury. This study analyzed the role of the antimicrobial peptide LL37 with mitochondrial DNA (LL37–mtDNA) and its potential mechanism of action in lipopolysaccharide (LPS)-treated rat type II alveolar epithelial cells (RLE-6TN cells). RLE-6TN cells were treated with LPS alone or with LL37–mtDNA, followed by transcriptome sequencing. Differentially expressed and pivotal genes were screened using bioinformatics tools. The effects of LL37–mtDNA on cell viability, inflammation, apoptosis, reactive oxygen species (ROS) production, and autophagy-related hallmark expression were evaluated in LPS-treated RLE-6TN cells. Additionally, the effects of Hsp90aa1 silencing following LL37–mtDNA treatment were investigated in vitro. LL37–mtDNA further suppressed cell viability, augmented apoptosis, promoted the release of inflammatory cytokines, increased ROS production, and elevated LC3B expression in LPS-treated RLE-6TN cells. Using transcriptome sequencing and bioinformatics, ten candidate genes were identified, of which three core genes were verified to be upregulated in the LPS + LL37–mtDNA group. Additionally, Hsp90aa1 downregulation attenuated the effects of LL37–mtDNA on LPS-treated RLE-6TN cells. Hsp90aa1 silencing possibly acted as a crucial target to counteract the effects of LL37–mtDNA on viability, apoptosis, inflammation, and autophagy activation in LPS-treated RLE-6TN cells.

Keywords

• ll37
• mtdna
• hsp90aa1
• autophagy
• sepsis-induced acute lung injury
• bioinformatics