The effect of glucagon-like Peptide-2 receptor agonists on colonic anastomotic wound healing

Abstract

Background. Glucagon-like peptide 2 (GLP-2) is an intestinal specific trophic hormone, with therapeutic potential; the effects on intestinal healing are unknown. We used a rat model of colonic healing, under normoxic, and stress (hypoxic) conditions to examine the effect of GLP-2 on intestinal healing. Methods. Following colonic transection and reanastomosis, animals were randomized to one of six groups (n = 8/group): controls, native GLP-2, long-acting GLP-2 (GLP-2- MIMETIBODY, GLP-2-MMB), animals were housed under normoxic or hypoxic (11% O(2)) conditions. Animals were studied five days post-operation for anastomotic strength and wound characteristics. Results. Anastomotic bursting pressure was unchanged by GLP-2 or GLP-2-MMB in normoxic or hypoxic animals; both treatments increased crypt cell proliferation. Wound IL-1β increased with GLP-2; IFNγ with GLP-2 and GLP-2-MMB. IL-10 and TGF-β were decreased; Type I collagen mRNA expression increased in hypoxic animals while Type III collagen was reduced with both GLP-2 agonists. GLP-2 MMB, but not native GLP-2 increased TIMP 1-3 mRNA levels in hypoxia. Conclusions. The effects on CCP, cytokines and wound healing were similar for both GLP-2 agonists under normoxic and hypoxic conditions; anastomotic strength was not affected. This suggests that GLP-2 (or agonists) could be safely used peri-operatively; direct studies will be required.

Figure 1

Crypt cell proliferation index. Proliferating cells in the ileal crypts were detected by BrdU immunohistochemical labelling; the index is the number of labelled cells per total cells in each half crypt, averaged from 5 or more crypts per animal, n = 5 or more per group. Data: mean ± SEM, *P < .05 versus the group indicated, †P < .05 versus similarly treated group under normoxic conditions. Comparisons by ANOVA.

Figure 2

Anastomotic bursting pressures of normoxic and hypoxic animals. Groups treated with GLP-2, GLP-2-mimetibody (MMB) and controls. Isolated segments of intestine insufflated with air under saline: pressure at which the first bubbles appear is recorded. (n = 7 or more per group, Data: mean ± SEM, *P < .05 versus similarly treated group under normoxic conditions. Comparisons by ANOVA).

Figure 3

Histological sections of colonic anastomosis (H and E × 4) ({indicates zone of inflammation, arrows; indicate zones of epithelial and muscular bridging}). Anastomotic healing scores in normoxic and hypoxic animals: treated with GLP-2, GLP-2 mimetibody (MMB) and controls. Rating scale 0–9, with 0 indicating perfect healing [5]. data: mean ± SEM; n = 7 or more per group.

Figure 4

Pro-inflammatory cytokines: IL1β (a), IFNγ (b) and TNFα (c) as measured by ELISA and normalized to protein content in anastomosed colon from normoxic and hypoxic animals treated with GLP-2, mimetibody or control. Data: mean ± SEM, n = 7 or more per group, *P < .05 by ANOVA.

Figure 5

Levels of anti-inflammatory/prohealing cytokines. (a) IL-10, (b), IL-13, and (c) TGFβ from anastomosed colon as determined by ELISA and normalized to protein content. Data: mean ± SEM, n = 7 or more per group, *P < .05 by ANOVA.

Figure 6

RT-PCR analysis of collagen and collagenase (MMP-13) mRNA Levels. mRNA expression of collagen I (a), collagen III (b), and matrix metalloproteinase 13 (c) in anastomotic tissue, as measured by RT-PCR normalized to β-actin. Data: mean ± SEM, n = 7 or more per group, *P < .05 versus the group indicated, by ANOVA.