A probiotic strain of Escherichia coli, Nissle 1917, given orally exerts local and systemic anti-inflammatory effects in lipopolysaccharide-induced sepsis in mice

Abstract

Background and purpose: Escherichia coli Nissle 1917 is a probiotic strain used in the treatment of intestinal immune diseases, including ulcerative colitis. The aim of the present study was to test if this probiotic bacterium can also show systemic immunomodulatory properties after oral administration.

Experimental approach: The probiotic strain was administered to rats or mice for 2 weeks before its assay in two experimental models of altered immune response, the trinitrobenzenesulphonic acid (TNBS) model of rat colitis, localized in the colon, and the lipopolysaccharide (LPS) model of systemic septic shock in mice. Inflammatory status was evaluated both macroscopically and biochemically after 1 week in the TNBS model or after 24 h in the LPS shock model. In addition, splenocytes were obtained from mice and stimulated, ex vivo, with concanavalin A or LPS to activate T or B cells, respectively, and cytokine production (IL-2, IL-5 and IL-10) by T cells and IgG secretion by B cells measured.

Key results: E. coli Nissle 1917 was anti-inflammatory in both models of altered immune response. This included a reduction in the pro-inflammatory cytokine tumour necrosis factor-alpha both in the intestine from colitic rats, and in plasma and lungs in mice treated with LPS. The systemic beneficial effect was associated with inhibited production of the T cell cytokines and by down-regulation of IgG release from splenocyte-derived B cells.

Conclusions and implications: The anti-inflammatory effects of E. coli Nissle 1917 given orally were not restricted to the gastrointestinal tract.

Figure 1

Histological sections of colonic mucosa from colitic rats 1 week after trinitrobenzenesulphonic acid (TNBS) treatment, stained with haematoxylin and eosin. (A) Non-colitic group showing the normal histology of the rat colon (original magnification ×20). (B) TNBS control group showing destruction of the mucosa, which has been replaced by inflammatory granulation tissue. There is evident edema and intense diffuse transmural inflammatory infiltrate (original magnification ×100). (C) Escherichia coli Nissle 1917-treated group showing amelioration in the inflammatory process and ‘restoration’ of the mucosal tissue with the presence of mucin-replenished goblet cells (original magnification ×100).

Figure 2

Effect of Escherichia coli Nissle 1917 on tumour necrosis factor-α production in lipopolysaccharide-induced septic shock in mice. Probiotic pretreatment inhibited production of this cytokine in plasma (A) and lungs (B). The concentrations (means ± SEM) of the cytokine were analysed by enzyme-linked immunosorbent assay (n= 10). *P < 0.05 versus control group; ^#P < 0.05 versus healthy group.

Figure 3

Effect of Escherichia coli Nissle 1917 on colonic inducible NO synthase (iNOS) expression in lipopolysaccharide-induced septic shock in mice. iNOS expression was analysed by Western blot using tissue homogenates as described in Methods; 150 µg of protein was loaded in each lane. β-Actin expression was used as control for loading and transfer.

Figure 5

Effects of treatment with Escherichia coli Nissle 1917 on IgG secretion in lipopolysaccharide (LPS)-stimulated splenocytes (A) and plasma (B) from mice with LPS-induced septic shock. Splenocytes were incubated with LPS (50 µg·mL⁻¹) for 72 h and the concentration (means ± SEM) of IgG in the supernatant was analysed by enzyme-linked immunosorbent assay (n= 10). *P < 0.05 versus control group; ^#P < 0.05 versus healthy group.

Figure 4

Effects of Escherichia coli Nissle 1917 on the secretion of the cytokines IL-2, IL-5 and IL-10 in Concanavalin (Con A)-activated splenocytes obtained from mice after lipopolysaccharide-induced septic shock. Splenocytes were incubated with Con A (5 µg·mL⁻¹) for 48 h and the concentration (means ± SEM) of the cytokine in the supernatant was analysed by enzyme-linked immunosorbent assay (n= 10). *P < 0.05 versus control group; ^#P < 0.05 versus healthy group.