Activin A exacerbates neonatal necrotizing enterocolitis via ALK4-mediated apoptosis and barrier disruption.

BACKGROUND

Necrotizing enterocolitis (NEC) is a life-threatening gastrointestinal disorder in neonates, yet the role of Activin A (ACV A) in NEC pathogenesis remains unclear.

METHODS

NEC was induced in neonatal mice through hypoxia, hypothermia, LPS, and formula feeding. An in vitro intestinal epithelial injury model was established using LPS-stimulated IEC-6 cells. Recombinant Activin A (rActivin A) and neutralizing antibody (anti-Activin A) were used for intervention. Comprehensive evaluations were performed to assess intestinal injury, barrier function (ZO-1 / Occludin / Claudin-1), inflammation (IL-1β/IL-6), and apoptosis through histopathology, ELISA, immunofluorescence, TUNEL, flow cytometry, and Western blotting. Specific inhibitors are utilized for reverse validation.

RESULTS

Activin A expression was significantly upregulated in intestinal tissues of NEC mice. Exogenous rActivin A worsened NEC outcomes, including weight loss, mortality, histopathological damage, and reduced tight junction proteins (ZO-1, Occludin, Claudin-1). This was accompanied by increased pro-inflammatory cytokines (IL-1β, IL-6) and epithelial apoptosis (Bax/Cleaved caspase-9 upregulation). Conversely, anti-Activin A reversed these effects. In vitro, Activin A enhanced LPS-induced IEC-6 apoptosis, which was abrogated by ALK4 inhibition. Mechanistically, Activin A activated Smad2/3 phosphorylation in an ALK4-dependent manner, without affecting NF-κB, ERK, or AKT pathways.

CONCLUSIONS

Activin A drives NEC progression through ALK4-Smad2/3-mediated apoptosis and barrier disruption. Targeting the Activin A-ALK4 axis may offer novel therapeutic strategies for NEC.