Fig. 4

Relationship between L. murinus and postoperative intestinal injury in patients undergoing cardiopulmonary bypass surgery. a, b Relative abundance of L. murinus in preoperative feces of CPB patients (n = 20) and healthy individuals (n = 6). c, d Changes in IFABP and citrulline concentrations at 6 h postoperatively (n = 10). e, f Correlation of relative L. murinus abundance with serum IFABP level and citrulline level. g Occurrence of gastrointestinal injury in patients undergoing CPB. h Relative abundances of L. murinus in the feces by real-time PCR between low L. murinus feces group and high L. murinus feces group (n = 6–8). i–k HE staining and ZO-1 and occludin immunofluorescent staining in the ileum and representative quantification. Scale bar = 100 μm (n = 6–8). l Relative mRNA levels of ZO-1 and occludin in the ileum (n = 6–8). m FD-4 level in the plasma (n = 6–8). The results are expressed as the mean ± SEM. ***p < 0.001, **p < 0.01, *p < 0.05 were determined by two-tailed Student’s t test and Spearman analysis in e, f. CPB, cardiopulmonary bypass; FD-4, FITC-dextran 4-KD; IFABP, Intestinal fatty acid-binding protein; L. murinus, Lactobacillus murinus