Tracking of Green Fluorescent Protein Labeled Escherichia coli Confirms Bacterial Translocation in Blind Loop Rat

Gut Microbiota Imbalance Can Be Associated with Non-malabsorptive Small Bowel Shortening Regardless of Blind Loop

INTRODUCTION

Some traditional bariatric surgery procedures may lead to functional gut shortening, which may unsettle the fine-tuned gastrointestinal physiology and affect gut microbiota balance.

PURPOSE

Evaluate the gut microbiota behavior in rat models facing gut shortening due to intestinal bypass.

MATERIALS AND METHODS

Wistar rats (n = 17) were randomly distributed in three groups: (1) sham group (n = 5); (2) blind loop group (n = 6); and (3) resection group (n = 6). Intestinal samples and feces were analyzed to measure bacterial concentrations (small intestinal bacterial overgrowth-SIBO) 12 weeks after the experimental procedures. Bacterial translocation (BT) was investigated in the mesenteric lymph node (MLN), liver, spleen, and lung of the animals. In addition, inflammatory aspects were investigated in their liver and small bowel through histological analysis.

RESULTS

Regardless of blind loop, gut shortening groups recorded similar high level of bacterial concentrations in intestine compartments, greater than that of the sham group (p ≤ 0.05). BT was only observed in the MLN of gut shortening models, with higher percentage in the blind loop group (p ≤ 0.05). The gut and liver histopathological analysis showed similar low-grade chronic inflammation in both gut shortening groups, likely associated with SIBO/BT events.

CONCLUSION

Sustained SIBO/BT was associated with proximal gut shortening in half regardless of blind loop, whereas the GI tract's ability to restore gut microbiota balance after a surgical challenge on the small bowel appears to be linked to the functional remaining gut.

Animal models to study acute and chronic intestinal inflammation in mammals

Acute and chronic inflammatory diseases of the intestine impart a significant and negative impact on the health and well-being of human and non-human mammalian animals. Understanding the underlying mechanisms of inflammatory disease is mandatory to develop effective treatment and prevention strategies. As inflammatory disease etiologies are multifactorial, the use of appropriate animal models and associated metrics of disease are essential. In this regard, animal models used alone or in combination to study acute and chronic inflammatory disease of the mammalian intestine paired with commonly used inflammation-inducing agents are reviewed. This includes both chemical and biological incitants of inflammation, and both non-mammalian (i.e. nematodes, insects, and fish) and mammalian (i.e. rodents, rabbits, pigs, ruminants, dogs, and non-human primates) models of intestinal inflammation including germ-free, gnotobiotic, as well as surgical, and genetically modified animals. Importantly, chemical and biological incitants induce inflammation via a multitude of mechanisms, and intestinal inflammation and injury can vary greatly according to the incitant and animal model used, allowing studies to ascertain both long-term and short-term effects of inflammation. Thus, researchers and clinicians should be aware of the relative strengths and limitations of the various animal models used to study acute and chronic inflammatory diseases of the mammalian intestine, and the scope and relevance of outcomes achievable based on this knowledge. The ability to induce inflammation to mimic common human diseases is an important factor of a successful animal model, however other mechanisms of disease such as the amount of infective agent to induce disease, invasion mechanisms, and the effect various physiologic changes can have on inducing damage are also important features. In many cases, the use of multiple animal models in combination with both chemical and biological incitants is necessary to answer the specific question being addressed regarding intestinal disease. Some incitants can induce acute responses in certain animal models while others can be used to induce chronic responses; this review aims to illustrate the strengths and weaknesses in each animal model and to guide the choice of an appropriate acute or chronic incitant to facilitate intestinal disease.

Effect of high-dose methotrexate chemotherapy on intestinal Bifidobacteria, Lactobacillus and Escherichia coli in children with acute lymphoblastic leukemia

High-dose methotrexate (HDMTX) chemotherapy is generally accepted as an effective method for the treatment and prevention of extramedullary leukemia in children. However, it is unknown whether HDMTX chemotherapy kills intestinal bacteria on a large scale, thus causing dysbacteriosis, which may in turn influence the progress or prognosis of leukemia. The aim of this study was to examine changes in intestinal flora in children with acute lymphoblastic leukemia (ALL) treated with HDMTX chemotherapy. Bacterial DNA in stool from 36 healthy children and 36 ALL children were tested at A(260) with a spectrophotometer before and after HDMTX chemotherapy. The primers of Bifidobacteria, Lactobacillus and Escherichia coli were designed according to the 16SrRNA/DNA bacterial sequences. Bacteria were qualitatively and quantitatively confirmed by routine polymerase chain reaction (PCR) and fluorescent quantitative PCR, respectively. Our data showed that the total amount of flora in the stools of children with ALL was decreased by 29.6% compared with healthy children (P < 0.01). The total amount of flora in the stools of children with ALL on the third and seventh days after chemotherapy were 1496.5 ± 577.1 and 1966.6 ± 598.3 ng/μL, respectively, which was notably less than before chemotherapy (2436.3 ± 768.6 ng/μL). The amount of Bifidobacteria, Lactobacillus and E. coli in the intestinal tract in the ALL group after chemotherapy had an apparent change, which decreased most clearly on the third day, and partially recovered on the seventh day after chemotherapy. HDMTX chemotherapy can cause intestinal dysbacteriosis in children with ALL. The amount of Bifidobacteria, Lactobacillus and E. coli decreased significantly compared with the control group.