Mechanism of Gzma-mediated GEF-H1 activation in intestinal epithelial cells leading to intestinal barrier dysfunction in sepsis.

Summary

Using clinical samples, transcriptomics, in vitro co-culture, and CLP mice, the study shows that Gzma activates GEF-H1 via Ser886 dephosphorylation, triggering RhoA/ROCK signaling, cytoskeletal remodeling, and tight junction loss that impair the intestinal barrier. GEF-H1 knockout mitigated injury and improved survival, while Epothilone A suppressed GEF-H1 activity, restored barrier integrity, and enhanced survival in murine sepsis.

Key Findings

• Gzma levels were elevated in sepsis and correlated with disease severity in clinical samples and CLP mice.
• Gzma activated GEF-H1 by dephosphorylating Ser886, triggering RhoA/ROCK signaling, MLC2/LIMK/cofilin phosphorylation, and cytoskeletal remodeling.
• GEF-H1 knockout preserved tight junctions, reduced intestinal injury, and improved survival, while pharmacologic activation worsened damage.
• High-throughput screening identified Epothilone A as a GEF-H1 modulator that restored barrier integrity and improved survival in murine sepsis.

Clinical Implications

Although preclinical, targeting GEF-H1 may protect the gut barrier and reduce multiple organ damage in sepsis. This supports biomarker-led selection of patients with barrier dysfunction and motivates early-phase trials of GEF-H1 modulators.

Limitations

• Preclinical evidence without human interventional validation
• Potential off-target effects and safety concerns of Epothilone A not assessed in sepsis patients

Future Directions

Develop pharmacodynamic biomarkers for GEF-H1 activity, perform dose-finding and safety studies of GEF-H1 modulators, and validate Gzma/GEF-H1 pathway markers in human sepsis with barrier dysfunction.