Eugenol accelerates intestinal stem cell regeneration to protect the intestinal barrier integrity through inhibiting JAK2/STAT3 signaling pathway in Salmonella enteritidis-challenged broiler chicks

Salmonella enteritidis is a prevalent foodborne pathogen causing diseases in humans and poultry globally. While clove extract is known for its anti-inflammatory properties, its specific effects on gut injury and underlying mechanisms are not well understood. A total of 432 one-day-old male fast-growing yellow-feathered broilers with similar body weight were randomly assigned to 6 groups, the CON and S.E were fed a basal diet; the CE and S.E + CE received 300 mg/kg of clove extract in their diets; and the EUG and S.E + EUG had 180 mg/kg of eugenol added to their basal diets. Moreover, a newly established ex vivo culture model for chick intestinal organoids (IOs) was used to evaluate intestinal stem cell (ISC) activity. Salmonella enteritis infection significantly reduced the growth performance and induced severe intestinal mucosa injury (P < 0.05). Dietary supplemented with clove extract or eugenol significantly improved average daily weight gain and feed intake, enhanced the structure and barrier function of the jejunum, reduced the bacterial load and diarrhea scores, promoted the proliferation and differentiation of ISCs, and diminished the efficiency, surface area, budding efficiency, and number of buds of intestinal organoids (P < 0.05). Both clove extract and eugenol down-regulated the protein expression of pro-inflammatory cytokines IL-1β, IL-6, and TNF-α. They also inhibited the excessive activation of the JAK2/STAT3 signaling pathway induced by Salmonella enteritidis infection in the jejunum tissues and crypts of chicks (P < 0.05). Eugenol, the active component in clove extract, alleviates intestinal inflammation by inhibiting the excessive activation of the JAK2/STAT3 signaling pathway. It promotes the proliferation and differentiation of ISCs, suppresses apoptosis, and accelerates ISCs-driven intestinal epithelial renewal in chicks, thereby maintaining the structural integrity and functional normalcy of the intestine.