Protective effects of lactococci strains delivering either IL-10 protein or cDNA in a TNBS-induced chronic colitis model

Abstract

Background: Oral treatment with Lactococcus (L.) lactis strains secreting the anti-inflammatory cytokine IL-10 has previously shown success as a therapy for inflammatory bowel diseases (IBD). Goals: Our aim was to compare the protective effects of IL-10, delivered by recombinant lactoccoci using two novel expression systems, in a murine colitis model mimicking the relapsing nature of IBD. The first system is based on a Stress-Inducible Controlled Expression (SICE) system for the production and delivery of heterologous proteins at mucosal surfaces and the second allows the delivery to the host cells of an il-10 cDNA cassette, harbored in a eukaryotic DNA expression vector (pValac). Study: Colitis was induced in female BALB/c mice by intrarectal injection of 2,4,6-trinitrobenzenesulphonic acid (TNBS). Mice that recovered received one of the bacteria treatments or saline solution orally during 14 days. Colitis was reactivated 25 days after the first TNBS injection with a second TNBS challenge. Three days after colitis reactivation, cytokine profiles and inflammation in colon samples were evaluated. Results: Animals (N=9) receiving L. lactis strains secreting IL-10 using SICE system or delivering pValac:il-10 plasmid showed lower weight loss (p<0.005), lower damage scores (p<0.005) and immune activation in their large intestines compared to inflamed non-treated mice. Conclusions: Our results confirm the protective effect of IL-10 delivered either as a protein or as a cDNA in a colitis model mimicking the relapsing nature of IBD and provides a step further in the ?proof-of-concept? of genetically engineered bacteria as a valid system to deliver therapeutic molecules at mucosal level.