A) Macroscopic Scores
B) Histological Scores
Dose 1 > Dose 2 > Dose 3 > Dose 4 > Dose 5Abbreviations: PBS = phosphate buffered saline; SEM = standard error of the mean; TNBS = 2,4,6-trinitrobenzene sulfonic acid. Vehicle = PBS/glycerolP-values are calculated in relation to the TNBS + Vehicle: *p<0.05; **p<0.01; ***p<0.001.Data are expressed as mean ± SEM of 3 pooled independent experiments.Vehicle n = 14; TNBS + Vehicle n = 29; TNBS + EXL01 Dose 1 n = 28; TNBS + EXL01 Dose 2 n = 27; TNBS + EXL01 Dose 3 n = 30; TNBS + EXL01 Dose 4 n = 19; TNBS + EXL01 Dose 5 n = 9; TNBS + Pentasa® n = 26.
Figure 1Colonic Macroscopic Scores (A) and Histological Scores (B) in Rats With TNBS-induced Colitis Following Administration of Different Doses of EXL01-strain by Oral Gavage
The anti-inflammatory properties and efficacy of the EXL01-strain administered by daily oral gavage (comparing 5 different doses) were assessed in an acute TNBS-induced colitis model in rats.
TNBS colitis model in rats is a well-established model of chemically-induced inflammation in the gut. This model employs rectal instillation of the mucosal sensitizing TNBS diluted in ethanol. TNBS haptenizes the localized colonic and gut microbial proteins to become immunogenic, triggering the host’s innate and adaptive immune responses. This model is considered a gold standard method to study Inflammatory Bowel Diseases (IBD); it reproduces many features of the inflammation seen in human Crohn’s disease including a similar cytokine profile, transmural inflammation and positive effects of the drugs currently used in Crohn’s disease (1).
The administration of Pentasa® (Mesalazine; 5-aminosalicylic acid, 150 mg/kg/day), the standard care treatment for colitis, was used as a positive control.
A strong anti-inflammatory effect of the EXL01-strain at daily doses of Dose 1, Dose 2, Dose 3 and Dose 4/day was observed at the macroscopic level; the percentage of improvement versus TNBS + Vehicle ranged from 29% (Dose 4/day) to 34% (Dose 1/day and Dose 2/day) after 11 days of oral administration in a dose-related manner (Figure 1A). No significant anti-inflammatory effect, at the macroscopic level, was reported for the EXL01-strain at the lowest tested doses of Dose 5/day. The anti-inflammatory effects of the EXL01-strain were greater than those induced by the Pentasa®, showing a higher efficacy to decrease the intensity of inflammation at the dosage of ≥ Dose 3/day.
Results obtained at the macroscopic level correlated with those obtained at the histological level; a statistically significant dose-dependent anti-inflammatory effect was recorded at the histological level for the EXL01-strain administered during the dose of Dose 1, Dose 2 and Dose 3/day (Figure 1B). The percentage improvement versus TNBS + Vehicle ranged from 22% (Dose 3/day) to 34% (Dose 1/day). No anti-inflammatory effects at the histological level were recorded at the lowest dosages of Dose 4 and Dose 5/day, or Pentasa® indicating a potentially higher efficacy of the EXL01-strain to decrease inflammation compared to a benchmark treatment currently in use for patients with IBD.
The EXL01-strain had no observed effects on the mortality rate, body weight evolution or inflammation, suggesting that the administration of the EXL01-strain, by daily oral gavage at doses Dose 1 to Dose 5/day, for 11 consecutive days, was well-tolerated under inflammatory and noninflammatory conditions.
1. Kiesler P, Fuss I J and Strober W. Experimental Models of Inflammatory Bowel Diseases. Cell. Mol. Gastroenterol. Hepatol. 2015;1(2);154-170.