Figure 1.

Lactococcus lactis. The probiotic L. lactis was engineered to produce different cytokines: interleukin 10 (IL-10), heme oxygenase 1 (HO-1), the Yersinia protein LcrV, TNF-α nanobodies, or trefoil factors. After oral administration, L. lactis secretes these proteins in direct proximity to mucosal surfaces. These proteins can modulate the immune system in different ways to dampen the immune response and establish tolerance to the microbiota in the case of mucosal injury during IBD or cancer treatment.