Overview
- Published in Science on Nov. 20, researchers report that an Aeromonas-produced aerolysin depletes gut macrophages linked to ulcerative colitis.
- Colon biopsies from patients showed resident macrophages were diminished in areas without epithelial inflammation, implying loss may precede disease flare.
- Biochemical profiling identified aerolysin as the macrophage‑toxic factor, with toxicity focused on macrophages rather than epithelial cells in vitro.
- In mice, infection with the macrophage‑toxic Aeromonas strain worsened colitis, aerolysin‑deficient mutants did not, and anti‑aerolysin antibodies prevented or reduced disease.
- Stool analyses found Aeromonas in 72% of UC patients versus 12% of healthy controls (2% in Crohn’s) with higher aerolysin levels, though current assays cannot single out the provisional MTB strain, underscoring the need for species‑specific diagnostics and further validation.