Targeting CXCL8 alleviates intestinal epithelial inflammation by suppressing the JAK-STAT pathway.

BACKGROUND: Inhibition of CXCL8 has been shown to alleviate small intestinal inflammation and suppress activation of Janus kinase-signal transducer and activator of transcription (JAK-STAT) signaling pathway. However, the mechanism of the interaction between the two requires further exploration. METHODS: Human small intestinal epithelial cells were stimulated with lipopolysaccharide (LPS) to establish an inflammatory model. The expression of pro-inflammatory factors was detected using qRT-PCR. Cell viability and apoptosis in cells treated with LPS or phosphate buffered saline (PBS) were assessed by CCK-8 assay and flow cytometry, respectively. Western blot was conducted to detect the expression of proteins linked to the JAK-STAT signaling pathway. Then, cell viability, apoptosis, and the expression of JAK-STAT pathway-associated protein were compared between si-CXCL8#1 and si-NC groups. Furthermore, after overexpressing STAT1 in si-CXCL8#1 group, changes in pro-inflammatory cytokine level, cell viability, and apoptosis were analyzed. RESULTS: Compared to the PBS control, LPS stimulation significantly increased apoptosis, promoted the release of pro-inflammatory mediators, upregulated JAK-STAT pathway protein expression, and reduced cell viability. CXCL8 silencing (si-CXCL8#1) enhanced cell viability, suppressed the release of pro-inflammatory mediators, decreased apoptosis, and downregulated the level of JAK-STAT signaling protein levels. Importantly, in comparison to the si-CXCL8#1 + oe-NC group, the apoptosis and expression of pro-inflammatory mediators were significantly elevated and cell viability was reduced in the si-CXCL8#1 + oe-STAT1 group. CONCLUSION: This study revealed that CXCL8 aggravated inflammation in small intestinal epithelial cells by activating the JAK-STAT pathway. Silencing CXCL8 alleviated LPS-induced inflammation and improved cell survival, which were reversed by STAT1 overexpression. These results highlighted the CXCL8-JAK-STAT axis as a potential therapeutic target for treating IBDs such as Crohn's disease.