Schistosoma mansoni proteins attenuate gastrointestinal motility disturbances during experimental colitis in mice

Abstract

Aim: To investigate the therapeutic effect of Schistosoma mansoni (S. mansoni) soluble worm proteins on gastrointestinal motility disturbances during experimental colitis in mice.

Methods: Colitis was induced by intrarectal injection of trinitrobenzene sulphate (TNBS) and 6 h later, mice were treated ip with S. mansoni proteins. Experiments were performed 5 d after TNBS injection. Inflammation was quantified using validated inflammation parameters. Gastric emptying and geometric center were measured to assess in vivo gastrointestinal motility. Peristaltic activity of distal colonic segments was studied in vitro using a modified Trendelenburg set-up. Cytokine profiles of T-lymphocytes isolated from the colon were determined by real time reverse transcriptase-polymerase chain reaction.

Results: Intracolonic injection of TNBS caused severe colitis. Treatment with S. mansoni proteins significantly ameliorated colonic inflammation after 5 d. TNBS did not affect gastric emptying but significantly decreased the geometric center and impaired colonic peristaltic activity 5 d after the induction of colitis. Treatment with S. mansoni proteins ameliorated these in vivo and in vitro motility disturbances. In addition, TNBS injection caused a downregulation of effector T cell cytokines after 5 d, whereas a S. mansoni protein effect was no longer observed at this time point.

Conclusion: Treatment with S. mansoni proteins attenuated intestinal inflammation and ameliorated motility disturbances during murine experimental colitis.

Figure 1

Effect of 25 μg Schistosoma mansoni soluble worm (SmSWP) proteins on clinical disease score (A), macroscopic score (B), extent of inflammation (C), microscopic score (D) and myeloperoxidase (MPO) activity (E) 5 d after trinitrobenzene sulphate (TNBS)-induced colitis. Grey bars represent phosphate-buffered saline (PBS)-treated TNBS mice; black bars represent SmSWP-treated TNBS mice. Data are presented as mean ± SE. Non-parametric data (A, B, D) were analyzed by the Mann-Whitney U test, parametric data (C, E) were analyzed by the Student’s t-test; n = 8-10; ^aP ≤ 0.05, significant effect of SmSWP treatment.

Figure 2

Effect of 25 μg S. mansoni proteins on geometric center 3 d (A) and 5 d (B) after the induction of colitis. Data were analyzed by two-way ANOVA with the Student-Newman-Keuls (SNK) post hoc test; n = 7-10; ^aP ≤ 0.05, significant colitis effect; ^cP ≤ 0.05, post hoc analysis showed a statistically significant difference from the other 3 groups.

Figure 3

Peristaltic tracings as recorded in the control-PBS group (A), the control-25 μg SmSWP group (B), the TNBS-PBS group on day 3 (C), the TNBS-PBS group on day 5 (D), the TNBS-25 μg SmSWP group on day 3 (E) and the TNBS-25 μg SmSWP group on day 5 (F).

Figure 4

Effect of 25 μg S. mansoni proteins on the amplitude and interval of peristaltic waves 3 d (A, B) and 5 d (C, D) after the induction of colitis. Data are presented as mean ± SE. Data were analyzed by two-way ANOVA with SNK post hoc test; n = 7-9 (except for the TNBS-PBS group on day 3 n = 4) ; ^aP ≤ 0.05, significant colitis effect; ^cP ≤ 0.05, post hoc analysis showed a significant difference from the other 3 groups.

Figure 5

Interferon (IFN) and interleukin (IL) mRNA expression of T helper (Th) 1 (A), Th17 (B), regulatory T (Treg) (C) and Th2 (D) cells isolated from colonic tissue at day 5. Data are expressed as relative expression and the control-PBS group was chosen as calibrator. Data are presented as mean ± SE. Data were analyzed by two-way ANOVA with SNK post hoc test when appropriate; n = 5-8 (except for IL-17 n = 2-5); ^aP ≤ 0.05, significant colitis effect, no significant effect of worm protein treatment was shown at day 5.