Probiotic pre-administration reduces mortality in a mouse model of cecal ligation and puncture-induced sepsis

Abstract

A number of clinical trials have demonstrated that the use of probiotics has the potential to prevent nosocomial infections. However, the mechanism underlying probiotic-induced anti-infection and sepsis remains to be investigated. In the present study, 200 µl/day of Lactobacillus rhamnosus GG (LGG) or normal saline (control) was orally administrated to 4-week-old C57BL6 mice 4 weeks prior to cecal ligation and puncture (CLP). A number of mice were sacrificed 24 h after CLP, and the remaining mice were used for survival studies. Ileum tissues were collected to evaluate the injury on the intestine. Blood samples were also obtained to investigate the changed metabolic pattern in mice that underwent different treatments using ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS). In the survival studies, the mortality of CLP-induced septic mice pretreated with LGG was significantly lower compared with untreated mice (P=0.029). Ileum mucosal damage was evident in the control septic mice. Based on the data of UPLC-QTOF-MS, phosphatidylcholines were increased and lysophosphatidylcholines (LPCs) that contained polyunsaturated fatty acids were decreased in septic mice, whereas saturated fatty acid LPCs reveal no significant difference between septic and sham mice. In addition, the metabolic profile in the septic mice pretreated with LGG was much closer to that of sham mice compared with control septic mice. The results of the present study suggest that probiotic pre-administration reduces the mortality in septic mice by decreasing ileum mucosal damage, increasing the gut barrier integrity and altering global serum metabolic profiles.

Keywords: Lactobacillus rhamnosus GG; cecal ligation and puncture; metabonomics; probiotic; sepsis; ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry.

Figure 1.

LGG decreases the mortality in cecal ligation and puncture (CLP)-induced sepsis. Four-week-old male C57BL6 mice pretreated with LGG (n=8) or saline (n=8) for 4 weeks were subjected to CLP. Sham mice (n=5) underwent sham laparotomy. Following surgery, all mice were observed for a 7 day survival rate. A total of 5 sham mice survived. *P=0.029. LGG, Lactobacillus rhamnosus GG.

Figure 2.

LGG pretreatment attenuates the injury of ileum mucosa. Hematoxylin and eosin-stained ileum sections from (A) sham mice, (B) control septic mice and (C) septic mice pretreated with LGG are shown. The examination of stained sections demonstrated normal intestinal mucosa and submucosa in (A) the sham mice. (B) The control septic mice exhibited villi exfoliation, lamina propria disintegration and severe inflammatory cell infiltration. Although some villi shedding remained, there was a normalized epithelial appearance with a large number of crypts and a mild level of inflammatory cell infiltration in (C) septic mice pretreated with LGG. The histological results suggested an improvement in the LGG pretreatment septic mice compared with the control septic mice. Upper panels, magnification ×40; bottom panels, magnification ×100. Sham, sham laparotomy mice; LGG+septic, cecal ligation and puncture (CLP) surgery with LGG pretreatment mice; Control septic, CLP surgery with saline pretreatment mice. LGG, Lactobacillus rhamnosus GG.

Figure 3.

Typical base peak intensity (BPI) chromatograms of serum samples from sham, septic mice pretreated with LGG and control septic mice. BPI chromatogram of a serum sample in one of the (A) sham mice, (B) septic mice pretreated with LGG and (C) control septic mice. Compared with the sham mice, a number of metabolites were increased in septic mice (hollow arrow) while others were decreased (black arrow). In addition, compared to the control septic mice, the peak patterns in septic mice pretreated with LGG were more similar to the sham mice (box).

Figure 4.

Supervised partial least squares discriminant analysis (PLS-DA). (A) PLS-DA score plot in positive ion mode based on UPLC-MS analysis data, showing that the three groups were clearly distinguished from each other. Black boxes represent the samples of septic mice pretreated with LGG, red diamonds represent the samples of control septic mice, blue diamonds represent the samples of sham mice. (B) PLS-DA score 3D plot in positive ion mode based on UPLC-MS analysis data. LGG, Lactobacillus rhamnosus GG; UPLC-MS, ultra-performance liquid chromatography mass spectrometry.