Fig. 5: Treatment of a STm-induced mouse model of colitis with LCB.

a In vitro Bacterial competition between STm and EcN. STm expressing mCherry were co-incubated with EcN in 96 well-plate at various ratios at 37 °C. The relative fluoresce units (RFUs) of mCherry reflecting the growth of STm were recorded by microplate reader at 1 h interval. b Experimental design for treatment. Mice were administrated with streptomycin one day before STm infection (1 × 10⁹ CFU) and then orally administrated with either PBS, uncoated EcN, or LCB by gavage at day 2 and 4 post-infection, respectively. Mice were sacrificed at day 6 post-infection. Blinded analysis was performed for ELISA and histopathological analysis. c The bacterial counts of STm in feces. At day 3, 5 and 6 post-infection, the feces were collected and resuspended in sterile PBS (0.1 g of fecal material in 2 ml of PBS). Fifty microliters of each sample was spread on selective agar plates and further incubated at 37 °C overnight before counting. d The bacterial loads of STm and EcN in the cecum. The cecum was harvested and then homogenized. Fifty microliters of each sample was spread on selective agar plates and further incubated at 37 °C overnight before counting. e Weight loss of mice administrated with PBS, uncoated EcN and LCB, respectively. f Levels of cytokines including IL-6 and IFN-γ in serum measured by commercially available ELISA kits. g Mean MPO positive cells counted in cecum. h Typical images of MPO staining of cecum. Error bars represent standard deviation (n = 5). Significance was assessed using Student’s t-test, giving p values, *p < 0.05, **p < 0.01, ***p < 0.005. Scale bar: 50 μm.