Glycyrrhiza polysaccharide attenuates Neospora caninum-induced intestinal epithelial cell damage by the C/EBPβ/IL-17/TNF signaling pathway

Intestinal epithelial cell (IEC) damage is a crucial event in pathogen-induced intestinal inflammation and systemic pathological responses, and their functional integrity directly affects animal health. This study used bovine intestinal epithelial cells (BIECs-21) and mouse models to examine the protective effects of Glycyrrhiza polysaccharide (GCP) against <i>Neospora caninum</i> (<i>NC</i>)-induced IEC damage and investigate its underlying mechanisms. <i>In vitro</i>, BIECs-21 were infected with <i>NC</i> to establish an intestinal epithelial injury model. <i>In vitro</i> experiments revealed that GCP pretreatment effectively inhibited <i>NC</i> infection-induced decreases in cell viability and lactate dehydrogenase (LDH) release, preserving intestinal epithelial homeostasis. Transcriptomic analysis results showed that <i>NC</i> infection activated the interleukin (IL)-17 and tumor necrosis factor (TNF) signaling pathways, increasing the expression of chemokines (CXCL1/2/3) and inflammatory genes (FOSB). In contrast, GCP inhibited the expression of transcription factors CCAAT/enhancer-binding protein β (C/EBPβ) and FOS, reduced pro-inflammatory factors (e.g., IL-6, IL1RAP), and mitigated excessive inflammatory responses. <i>In vivo</i> experiments confirmed that low-dose GCP intervention significantly reduced intestinal hemorrhage and edema, decreased parasite loads in intestinal and cerebral tissues of infected mice, and suppressed protein expression of IL-17RA, TNF-<i>α</i>, p-C/EBPβ and p-NF-κB in intestinal tissues. These findings demonstrate that GCP mitigates <i>NC</i>-induced IEC injury by modulating intestinal immune homeostasis through the C/EBPβ/IL-17/TNF signaling pathway, thus establishing a theoretical basis for developing natural therapeutics against pathogen-induced gut damage.