Ulinastatin relieves sepsis-associated dysmotility via IL-1β-related enteric neuroprotection

To evaluate the comprehensive protective effects of ulinastatin (UTI) on intestinal structure and function during sepsis and to explore whether UTI restores intestinal motility through mechanisms involving attenuation of interleukin-1β (IL-1β)-mediated inflammation.

A murine cecal ligation and puncture (CLP) model was established and mice received intravenous UTI. Primary outcomes included 7-day survival, time to first black stool, fecal output, small-intestinal transit, and blinded histopathology. Barrier integrity was assessed by Alcian Blue-Periodic Acid-Schiff staining for goblet-cell mucin and Claudin-1 immunofluorescence; inflammation by IL-1β, tumor necrosis factor (TNF)-α, and IL-6; and enteric nerve integrity by counting HuD-positive neurons and measuring PGP9.5-labeled nerve fibers. To assess direct effects, primary enteric neurons were stimulated with lipopolysaccharide or IL-1β in vitro. An IL-1β-neutralizing antibody (nAb) was used alone or with UTI to interrogate mechanism.

UTI improved survival, shortened stool latency, increased pellet output, and enhanced transit after CLP. UTI attenuated intestinal injury, restored goblet-cell mucin production and Claudin-1 expression, and reduced systemic and colonic IL-1β, TNF-α, and IL-6. Moreover, UTI also increased the number of HuD⁺ enteric neurons and preserved PGP9.5-labeled nerve fiber networks. In vitro, UTI preserved βIII-tubulin-defined neuronal morphology and reduced IL-1β secretion. IL-1β nAb reproduced the protective benefits on enteric nerve and intestinal motility; no significant additive benefits were observed when IL-1β nAb was combined with UTI.

UTI confers broad and integrated protection of the intestine during sepsis. These findings suggest that IL-1β-mediated inflammatory signaling plays a key role in UTI-induced enteric neuroprotection and restoration of intestinal motility.