Oral administration of AvCys-secreting EcN (EcN-AvCys) on alternate days attenuated DSS colitis by beneficial regulation of the immune system in the inflamed colon (regulation of the proportion and function of pro-inflammatory macrophages, increase in the proportion of FoxP3+ Treg cells, and decrease in inflammatory cytokines and chemokines). The gene discussed is FOXP3; the disease is colitis.