Synergic Interaction of Rifaximin and Mutaflor (Escherichia coli Nissle 1917) in the Treatment of Acetic Acid-Induced Colitis in Rats

Abstract

Background. Inflammatory bowel disease results from the dysregulation of immune response to environmental and microbial agents in genetically susceptible individuals. The aim of the present study was to examine the effect of rifaximin and/or Mutaflor (Escherichia coli Nissle 1917, EcN) administration on the healing of acetic acid-induced colitis. Methods. Colitis was induced in male Wistar rats by rectal enema with 3.5% acetic acid solution. Rifaximin (50 mg/kg/dose) and/or Mutaflor (10(9) CFU/dose) were given intragastrically once a day. The severity of colitis was assessed at the 8th day after induction of inflammation. Results. Treatment with rifaximin significantly accelerated the healing of colonic damage. This effect was associated with significant reversion of the acetic acid-evoked decrease in mucosal blood flow and DNA synthesis. Moreover, administration of rifaximin significantly reduced concentration of proinflammatory TNF-α and activity of myeloperoxidase in colonic mucosa. Mutaflor given alone was without significant effect on activity of colitis. In contrast, Mutaflor given in combination with rifaximin significantly enhanced therapeutic effect of rifaximin. Moreover, Mutaflor led to settle of the colon by EcN and this effect was augmented by pretreatment with rifaximin. Conclusion. Rifaximin and Mutaflor exhibit synergic anti-inflammatory and therapeutic effect in acetic acid-induced colitis in rats.

Figure 1

Influence of E. coli Nissle 1917 (Mutaflor) and rifaximin on the area of colonic lesions in rats without or with acetic acid-induced colitis. Mean value ± SEM. N = 8 animals in each experimental group. ^a P < 0.05 compared to control saline-treated rats without induction of colitis; ^b P < 0.05 compared to colitis + NaCl; ^c P < 0.05 compared to colitis + Mutaflor; and ^d P < 0.05 compared to colitis + rifaximin.

Figure 2

Histological features of the rat colonic mucosa stained by haematoxylin and eosin (original magnification 400x). (a) Control rats without induction of colitis and treated with saline for 7 days; (b) rats with colitis treated with saline for 7 days; (c) rats with colitis treated with Mutaflor for 7 days; (d) rats with colitis treated with rifaximin for 7 days; and (e) rats with colitis treated with the combination of rifaximin plus Mutaflor for 7 days.

Figure 3

Influence of E. coli Nissle 1917 (Mutaflor) and rifaximin on mucosal blood flow in the colon in rats without or with acetic acid-induced colitis. Mean value ± SEM. N = 8 animals in each experimental group. ^a P < 0.05 compared to control saline-treated rats without induction of colitis; ^b P < 0.05 compared to colitis + NaCl; and ^c P < 0.05 compared to colitis + Mutaflor.

Figure 4

Influence of E. coli Nissle 1917 (Mutaflor) and rifaximin on DNA synthesis in colonic mucosa in rats without or with acetic acid-induced colitis. Mean value ± SEM. N = 8 animals in each experimental group. ^a P < 0.05 compared to control saline-treated rats without induction of colitis; ^b P < 0.05 compared to colitis + NaCl.

Figure 5

Influence of E. coli Nissle 1917 (Mutaflor) and rifaximin on of interleukin-1β concentration in colonic mucosa in rats without or with acetic acid-induced colitis. Mean value ± SEM. N = 8 animals in each experimental group. ^a P < 0.05 compared to control saline-treated rats without induction of colitis; ^b P < 0.05 compared to colitis + NaCl; ^c P < 0.05 compared to colitis + Mutaflor; and ^d P < 0.05 compared to colitis + rifaximin.

Figure 6

Influence of E. coli Nissle 1917 (Mutaflor) and rifaximin on of Tumor Necrosis Factor-α concentration in colonic mucosa in rats without or with acetic acid-induced colitis. Mean value ± SEM. N = 8 animals in each experimental group. ^a P < 0.05 compared to control saline-treated rats without induction of colitis; ^b P < 0.05 compared to colitis + NaCl; ^c P < 0.05 compared to colitis + Mutaflor; and ^d P < 0.05 compared to colitis + rifaximin.

Figure 7

Influence of E. coli Nissle 1917 (Mutaflor) and rifaximin on myeloperoxidase activity in colonic mucosa in rats without or with acetic acid-induced colitis. Mean value ± SEM. N = 8 animals in each experimental group and each time of observation. ^a P < 0.05 compared to control saline-treated rats without induction of colitis; ^b P < 0.05 compared to colitis + NaCl; ^c P < 0.05 compared to colitis + Mutaflor; and ^d P < 0.05 compared to colitis + rifaximin.

Figure 8

Determination of Muta 5/6 (361 bp), Muta 7/8 (427 bp), and Muta 9/10 (313 bp) amplicons by PCR method as indices of the presence of E. coli Nissle 1917 (EcN). Representative findings in (line 1) control rats without induction of colitis and treated intragastrically (i.g.) with saline; (line 2) rats without induction of colitis and treated i.g. with Mutaflor; (line 3) rats without induction of colitis and treated i.g. with rifaximin; (line 4) rats without induction of colitis and treated i.g. with the combination of rifaximin plus Mutaflor; (line 5) rats treated i.g. with saline after induction of colitis; (line 6) rats treated i.g. with Mutaflor after induction of colitis; (line 7) rats treated i.g. with rifaximin after induction of colitis; and (line 8) rats treated i.g. with the combination of rifaximin plus Mutaflor after induction of colitis. Line M—DNA mass ruler.