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)-1β, tumour necrosis factor (TNF), transforming growth factor β, 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-1β, 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.
Interleukin (IL)‐10‐deficient (IL‐10−/−) mice develop colitis under specific pathogen‐free (SPF) conditions and remain disease free if kept sterile (germ free GF). We used four different protocols ...that varied the time‐points of oral administration of Lactobacillus plantarum 299v (L. plantarum) relative to colonization with SPF bacteria to determine whether L. plantarum could prevent and treat colitis induced by SPF bacteria in IL‐10−/− mice and evaluated the effect of this probiotic organism on mucosal immune activation. Assessment of colitis included blinded histologic scores, measurements of secreted colonic immunoglobulin isotypes, IL‐12 (p40 subunit), and interferon (IFN)‐γ production by anti‐CD3‐stimulated mesenteric lymph node cells. Treating SPF IL‐10−/− mice with L. plantarum attenuated previously established colonic inflammation as manifested by decreased mucosal IL‐12, IFN‐γ, and immunoglobulin G2a levels. Colonizing GF animals with L. plantarum and SPF flora simultaneously had no protective effects. Gnotobiotic IL‐10−/− mice monoassociated with L. plantarum exhibited mild immune system activation but no colitis. Pretreatment of GF mice by colonization with L. plantarum, then exposure to SPF flora and continued probiotic therapy significantly decreased histologic colitis scores. These results demonstrate that L. plantarum can attenuate immune‐mediated colitis and suggest a potential therapeutic role for this agent in clinical inflammatory bowel diseases.
Interleukin-2 (IL-2) amplifies immune stimuli and influences B cell differentiation. IL-2-deficient mice spontaneously develop intestinal inflammation if raised under specific pathogen-free (SPF) ...conditions. We quantitatively determined the aggressiveness and kinetics of gastrointestinal and hepatic inflammation in the presence or absence of viable bacteria in IL-2-deficient mice. Breeding colonies were maintained under SPF and germfree (GF) conditions. Intestinal tissues, serum, and mesenteric lymph nodes were obtained from mice at different ages for blind histological scoring, immunoglobulin measurements, mucosal T cell infiltration, and cytokine secretion. GF IL-2 -/- mice developed mild, focal, and nonlethal intestinal inflammation with delayed onset, whereas the more aggressive inflammation in SPF IL-2 -/- mice led to their death between 28 and 32 wk. Periportal hepatic inflammation was equal in the presence or absence of bacterial colonization. Intestinal immunoglobulin secretion decreased significantly by 13 wk of age in IL-2 -/- mice in both GF and SPF environments. In contrast to other genetically engineered rodents, IL-2 -/- mice develop mild focal gastrointestinal and active portal tract inflammation in the absence of viable bacteria.
Normal resident bacteria are required for development of colitis in several rodent models. We determined whether bacterial stimulation is necessary for both induction and perpetuation of mucosal ...inflammation and T-cell activation in Tg(epsilon26) mice, in which transplantation of wild-type bone marrow (BM-->Tg(epsilon26)) causes colitis under specific pathogen-free (SPF) conditions.
BM from (C57BL/6 X CBA/J) F1 mice was transplanted into germfree (GF) or SPF Tg(epsilon26) mice. Mesenteric lymph node (MLN) cells from these mice were then transferred into SPF or GF recipients. Colitis and activation of MLN cells were measured by histologic scores, membrane marker analysis, and intracellular cytokine staining. Cytokine secretion by MLN cells stimulated by anti-CD3 or by luminal or epithelial antigens was measured by ELISA.
Colitis did not develop when BM was transferred into GF recipient mice (BM-->GF Tg(epsilon26)). T lymphocytes that secreted interferon gamma upon activation were present in the MLN of BM-->GF Tg(epsilon26) mice, albeit in lower frequency than in control BM-->SPF Tg(epsilon26) mice. Furthermore, transfer of MLN cells from BM-->SPF Tg(epsilon26) mice into SPF Tg(epsilon26) recipients induced active colitis, but not if the same cells were transferred into GF Tg(epsilon26) recipients. Although CD4 T cells were detected in the colonic mucosa of GF recipients, no inflammation was observed for at least 31 weeks. In a reciprocal experiment, MLN cells from BM-->GF Tg(epsilon26) mice without colitis transferred disease to SPF Tg(epsilon26) recipients within 2-4 weeks.
Activated T cells are present in the mucosa of BM-->GF Tg(epsilon26) mice but are incapable of inducing disease unless colonic bacteria are present. Moreover, pathogenic T cells require the continuous presence of colonic bacteria to sustain colitis.
Interleukin-2 (IL-1) amplifies immune stimuli and influences B cell differentiation. IL-2-deficient mice spontaneously develop intestinal inflammation if raised under specific pathogen-free (SPF) ...conditions.
Genetic and environmental factors are important in the pathogenesis of clinical and experimental chronic intestinal inflammation. We investigated the influence of normal luminal bacteria and several ...groups of selected bacterial strains on spontaneous gastrointestinal and systemic inflammation in HLA-B27 transgenic rats. Rats maintained germfree for 3-9 mo were compared with littermates conventionalized with specific pathogen-free bacteria. Subsequently, germfree transgenic rats were colonized with groups of five to eight bacteria that were either facultative or strictly anaerobic. Transgenic germfree rats had no gastroduodenitis, colitis, or arthritis, but developed epididymitis and dermatitis to the same degree as conventionalized rats. Colonic proinflammatory cytokine expression was increased in transgenic conventionalized rats but was undetectable in germfree and nontransgenic rats. Colitis progressively increased over the first 4 wk of bacterial exposure, then plateaued. Only transgenic rats colonized with defined bacterial cocktails which contained Bacteroides spp. had colitis and gastritis. Normal luminal bacteria predictably and uniformly induce chronic colonic, gastric and systemic inflammation in B27 transgenic F344 rats, but all bacterial species do not have equal activities.
Genetic and environmental factors are important in the pathogenesis of clinical and experimental chronic intestinal inflammation. We investigated the influence of normal luminal bacteria and several ...groups of selected bacterial strains on spontaneous gastrointestinal and systemic inflammation in HLA-B27 transgenic rats. Rats maintained germfree for 3-9 mo were compared with littermates conventionalized with specific pathogen-free bacteria. Subsequently, germfree transgenic rats were colonized with groups of five to eight bacteria that were either facultative or strictly anaerobic. Transgenic germfree rats had no gastroduodenitis, colitis, or arthritis, but developed epididymitis and dermatitis to the same degree as conventionalized rats. Colonic proinflammatory cytokine expression was increased in transgenic conventionalized rats but was undetectable in germfree and nontransgenic rats. Colitis progressively increased over the first 4 wk of bacterial exposure, then plateaued. Only transgenic rats colonized with defined bacterial cocktails which contained Bacteroides spp. had colitis and gastritis. Normal luminal bacteria predictably and uniformly induce chronic colonic, gastric and systemic inflammation in B27 transgenic F344 rats, but all bacterial species do not have equal activities.
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