To understand the anti-colitic effects of probiotics that up-regulate interleukin (IL)-10 expression in dendritic cells (DCs) and macrophages, we isolated Lactobacillus sakei K17, which potently induced IL-10 expression in DCs and peritoneal macrophages in vitro, among the lactic acid bacteria strains collected from kimchi and investigated its anti-inflammatory effect in mice with 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced colitis. Oral administration of K17 (2 x 10(9) CFU.mouse(-1).day(-1)) in mice with TNBS-induced colitis suppressed colon shortening and myeloperoxidase activity, as well as infiltration of CD86(+ )cells into the colon. Treatment with K17 also increased TNBS-suppressed expression of tight junction proteins and IL-10, but inhibited activation of nuclear factor-kappaB (NF-kappaB) and mitogen-activated protein kinases and expression of tumor necrosis factor alpha and IL-17. Its effect was comparable with that of sulfasalazine (50 mg/kg), a positive commercial ant-colitic drug. Furthermore, treatment with K17 (1 x 10(5) CFU/mL) potently inhibited lipopolysaccharide (LPS)-stimulated NF-kappaB activation in DCs and peritoneal macrophages and restored tight junction protein expression in LPS-stimulated Caco-2 cells. These findings suggest that Lactobacillus sakei K17 may ameliorate colitis by up-regulating the expression of IL-10 and tight junction proteins and inhibiting NF-kappaB activation.