Administration of Lactobacillus paracasei strains improves immunomodulation and changes the composition of gut microbiota leading to improvement of colitis in mice

•L. paracasei modulates cytokines and T regulatory cells in an in vivo model.•L. paracasei has protective effects on intestinal tight junctions and mucus layers.•L. paracasei treatment alters the diversity and composition of gut microbiota.•L. paracasei could be effective in preventing inflammatory bowel disease.