Lactobacillus GG prevents recurrence of colitis in HLA-B27 transgenic rats after antibiotic treatment

Abstract

Background and aims: Bacteroides vulgatus induces colitis in gnotobiotic HLA-B27 transgenic (TG) rats while broad spectrum antibiotics prevent and treat colitis in specific pathogen free (SPF) TG rats although disease recurs after treatment ends. Lactobacilli treat human pouchitis and experimental colitis. We investigated if Lactobacillus rhamnosus GG (L GG) can prevent colitis in TG rats monoassociated with B vulgatus and if L GG or Lactobacillus plantarum 299v (LP 299v) can treat established colitis in SPF TG rats and prevent recurrent disease after antibiotics were stopped.

Methods: Germfree B27 TG rats were monoassociated with B vulgatus for four weeks following two weeks of colonisation with L GG or no bacteria. SPF B27 TG rats received oral vancomycin and imipenem for two weeks, or water alone, followed by four weeks of treatment with oral L GG, LP 299v, or water only. Disease activity was quantified by blinded gross and histological scores, caecal myeloperoxidase (MPO) activity, and levels of interleukin (IL)-1 beta, tumour necrosis factor (TNF), transforming growth factor beta, and IL-10.

Results: L GG did not prevent colitis in B vulgatus co-associated TG rats or treat established disease in SPF rats. However, L GG but not LP 299v prevented colitis relapse in antibiotic treated rats with reduced gross and histological scores, caecal MPO, IL-1 beta, and TNF whereas caecal IL-10 was increased.

Conclusions: L GG does not prevent colitis in gnotobiotic TG rats or treat established disease in SPF rats, but is superior to LP 299v in the prevention of recurrent colitis. These studies suggest that antibiotics and probiotic agents provide synergistic therapeutic effects, perhaps mediated by altered immunomodulation with selective activity of different lactobacillus species.

Figure 1

Gross gut scores (0–4) of caeca from specific pathogen free (SPF) transgenic (TG) rats treated with vancomycin/imipenem (Abs) or water followed by oral Lactobacillus rhamnosus GG (L GG) or water administration. Gross gut scores from untreated SPF TG rats are also given. Each group consisted of six rats. Data are expressed as mean (SEM). **p<0.01 versus untreated control rats.

Figure 2

Representative photomicrographs of tissue sections (×40) from caeca of 16 week old specific pathogen free (SPF) transgenic (TG) rats which were treated with: (A) water; (B) two weeks oral vancomycin/imipenem followed by four weeks of water; (C) two weeks oral of vancomycin/imipenem followed by daily administration of Lactobacillus rhamnosus GG (L GG) over four weeks; and (D) two weeks of water followed by four weeks of oral L GG. Note the extensive mucosal and some submucosal inflammation as well as significant crypt hyperplasia in caeca in (A), (B), and (D). Only mild to modest mucosal inflammation was seen in TG rats treated with the combination of broad spectrum antibiotics followed by L GG (C).

Figure 3

Blinded total colonic inflammatory scores in specific pathogen free (SPF) transgenic (TG) rats treated for two weeks with oral broad spectrum antibiotics (Abs) or water followed by four weeks of Lactobacillus rhamnosus GG (L GG), Lactobacillus plantarum strain 299v (L pl), or water. Also, histology scores from SPF TG untreated rats are given. Values represent mean (SEM) of total histology scores (0–4). Vancomycin/imipenem followed by daily oral L GG administration significantly decreased total colonic histology scores versus other treatment groups. Feeding LP 299v did not prevent colitis relapse nor did it treat established colitis. *p<0.05 versus other treatment groups. Each group consisted of six SPF TG rats.

Figure 4

Caecal myeloperoxidase (MPO) concentrations in specific pathogen free (SPF) transgenic (TG) rats treated for two weeks with oral broad spectrum antibiotics (Abs) or water followed by four weeks of Lactobacillus rhamnosus GG (L GG), or water. Values from untreated TG control rats are also given. Data represent mean (SEM) MPO levels in units per gram of caecum. *p< 0.05 versus untreated controls.

Figure 5

Caecal interleukin (IL)-1β (A), and tumour necrosis factor (TNF), IL-10, and transforming growth factor β (TGF-β) (B) concentrations (pg/mg) from transgenic (TG) rats treated for two weeks with oral broad spectrum antibiotics (Abs) or water followed by four weeks of Lactobacillus rhamnosus GG (L GG) or water as well as from untreated controls. Values are mean (SEM). *p<0.05 versus untreated controls. The combination of antibiotics followed by L GG significantly decreased caecal IL-1β and TNF but also increased mucosal IL-10 concentrations.

Figure 6

Dose dependent inhibition of in vitro adherence of 10⁹ CFU B vulgatus/2 ml well to IEC-6 cells by Lactobacillus rhamnosus GG (L GG). Data represent concentrations (×10³ CFU) of adherent B vulgatus after three hours of incubation with IEC-6 monolayers in the presence or absence of 10⁸ or 10⁹ CFU L GG/2 ml well. Values are mean (SEM). **p<0.01 versus B vulgatus control.