Pea-protein alginate capsules as a delivery system for probiotic bacteria in a mouse model of Citrobacter rodentium-induced colitis

The efficacy of two strains of Lactobacillus probiotics (Lactobacillus rhamnosus strain R0011 and Lactobacillus helveticus strain R0052) immobilized in pea protein isolate (PPI) - alginate microcapsules was assessed using a mouse model of Citrobacter rodentium-induced colitis. Accordingly, 4-week old mice were fed diets supplemented with freeze-dried probiotics (group P), probiotic containing microcapsules (group PE) (lyophilized PPI-alginate microcapsules containing probiotics) or PPI-alginate microcapsules containing no probiotics (group E). Half the mice (controls, groups P, PE and E) were gavaged with C. rodentium 2 weeks after initiation of feeding. Daily monitoring of disease symptoms (abnormal behavior, diarrhea, etc.) and body weights were undertaken. Histopathological changes in colonic and cecal tissues, cytokine expression levels, pathogen and probiotic densities in feces, as well as 16s rRNA-based sequencing of mucosal microbial communities in the distal colon were also performed. Infection with C. rodentium led to marked progression of infectious colitis, as revealed by symptomatic and histopathological data, changes in cytokine expression, and alteration of composition of mucosal communities. Probiotics led to changes in most of the disease markers, but did not have a significant impact on cytokine profiles in infected animals. Based on cytokine expression analyses and histopathological data, it was evident that encapsulation materials (pea protein and calcium alginate) contributed to inflammation and worsened a set of symptoms in the cecum. These results suggest that even though food ingredients may be generally recognized as safe, they may in fact contribute to the development of an inflammatory response in certain animal disease models.