LPS‑induced inflammatory response and apoptosis are mediated by Fra‑1 upregulation and binding to YKL‑40 in A549 cells

Abstract

Acute respiratory distress syndrome (ARDS) is a multifactorial syndrome that leads to increased morbidity and mortality in infants and children. The identification of novel biomarkers is critical for the treatment of ARDS. The present study aimed to investigate the effects of chitinase-3-like-1 protein (CHI3L1 or YKL-40) in an in vitro model of ARDS and to explore the potential underlying mechanisms. The in vitro model of ARDS was established in A549 alveolar epithelial type II cells, which were treated by lipopolysaccharide (LPS) to induce inflammation. Transfection was performed to alter YKL-40 expression. The mRNA and protein expression of YKL-40 was determined using reverse transcription-quantitative PCR and western blotting, respectively. Cell Counting Kit-8 and TUNEL assays were used to evaluate the cell viability and apoptosis, respectively. The production of cytokines was evaluated using specific ELISA kits. The relationship between YKL-40 and Fos-related antigen 1 (Fra-1) was verified using luciferase reporter and chromatin immunoprecipitation assays. The expression of the apoptotic proteins was detected using western blotting. The expression levels of YKL-40 and Fra-1 were increased in LPS-treated A549 cells. Higher levels of pro-inflammatory cytokines and induction of cell apoptosis were observed in LPS-treated A549 cells compared with the control. YKL-40 knockdown in LPS-treated A549 cells significantly decreased the production of pro-inflammatory cytokines and reduced cell apoptosis, whereas it concomitantly caused upregulation of Bax and downregulation of Bcl-2, cleaved caspase-3 and cleaved caspase-9. In addition, Fra-1 could directly bind to YKL-40 promoter and regulate its expression level. Overexpression of YKL-40 partly decreased the inhibitory effects of Fra-1 knockdown on the inflammatory response and induction of apoptosis. In summary, the findings from the present study indicated that Fra-1 could bind to YKL-40 and regulate its expression, whereas YKL-40 knockdown could further suppress LPS-induced inflammatory response and apoptosis in A549 cells. These data may provide novel evidence on the diagnosis and therapy of ARDS.

Mangiferin attenuates lipopolysaccharide-induced neuronal injuries in primary cultured hippocampal neurons

“…injection of lipopolysaccharide (LPS) is a widely accepted method for establishing animal models of sepsis. Increasing in vivo studies have shown that LPS-induced inflammation causes inappropriate activation of microglia and astrocytes, damages the BBB, and negatively affects mitochondrial function, oxidative/nitrative stress, and apoptosis [ 20 , 21 ]. Although mangiferin shows excellent protective effects against sepsis-induced lung or kidney injury [ 14 , 15 ], the neuroprotective effects of mangiferin have not been investigated in LPS-induced sepsis using primary cultured hippocampal neurons.…”

Lacticaseibacillus rhamnosus dfa1 Attenuate Cecal Ligation-Induced Systemic Inflammation through the Interference in Gut Dysbiosis, Leaky Gut, and Enterocytic Cell Energy

“…Although the systemic inflammation after cecal ligation was not severe enough to induce kidney or liver injury, different from the inflammation of the gut–kidney–liver axis in sepsis [ 7 ], the significant inflammatory responses in cecal-ligated mice were demonstrated by an increase in apoptosis of spleen. Indeed, the overwhelming inflammatory activation can cause apoptosis in several cell types is well-known [ 27 , 61 ].…”