# Multifaceted intestinal defense following experimental blunt abdominal trauma

## TL;DR

This study shows that the intestine responds to blunt abdominal trauma by preserving its barrier and activating protective immune mechanisms.

## Contribution

The study reveals a multifaceted intestinal defense response to blunt trauma, including preserved barrier integrity and adaptive immune activation.

## Key findings

- Jejunal tissue showed no histomorphological changes but exhibited upregulated barrier proteins like E-cadherin and tight-junction protein 1.
- Blunt trauma activated defense pathways, increased S100A8 expression, and enhanced CD3+ T cell infiltration.
- Mucus-covered areas decreased despite elevated MUC2 and C1GALT1 transcription, and antimicrobial peptide CRAMP was upregulated.

## Abstract

Blunt abdominal trauma (AT) can cause significant intestinal injury and act as a trigger for remote posttraumatic organ dysfunction, including the development of multi-organ dysfunction syndrome (MODS). A deeper understanding of its impact on intestinal barrier integrity and immune regulation is essential for developing therapeutic strategies that support posttraumatic recovery.

We assessed jejunal tissue 24 hours following a standardized murine blast-induced direct blunt AT. Histological, immunohistochemical, proteome profiling, Western Blot, and molecular analyses were applied to assess epithelial integrity, barrier-associated proteins, intestinal mucus composition, and immune responses.

The jejunum showed no trauma-specific histomorphological changes. Consistently, the expression of key epithelial barrier proteins, such as E-cadherin and tight-junction protein 1, remained stable or were even upregulated. Local inflammatory responses were evident; AT induced activation of defense-related pathways, accompanied by a marked increase in S100A8 expression and enhanced infiltration of CD3+ T cells. Mucus-covered areas of the intestinal surface were reduced, although transcriptional levels of MUC2 and C1GALT1 were elevated. In addition, the antimicrobial peptide CRAMP was upregulated in jejunal tissue following injury.

These findings suggest that the intestine initiates a multifaceted protective response to blunt AT, characterized by barrier preservation, mucus alterations, and adaptive immune activation. Remarkably, although the trauma was sufficient to elicit an inflammatory reaction, it simultaneously activated mechanisms that reinforced epithelial integrity and compensatory processes that may counteract barrier disruption in the early posttraumatic phase.

The online version contains supplementary material available at 10.1007/s00068-026-03145-0.