Gut microbiota influence anastomotic healing in colorectal cancer surgery through modulation of mucosal proinflammatory cytokines.

OBJECTIVE: Colorectal cancer (CRC) is the third most diagnosed cancer, and requires surgical resection and reconnection, or anastomosis, of the remaining bowel to re-establish intestinal continuity. Anastomotic leak (AL) is a major complication that increases mortality and cancer recurrence. Our objective is to assess the causal role of gut microbiota in anastomotic healing. DESIGN: The causal role of gut microbiota was assessed in a murine AL model receiving faecal microbiota transplantation (FMT) from patients with CRC collected before surgery and who later developed or not, AL. Anastomotic healing and gut barrier integrity were assessed after surgery. Bacterial candidates implicated in anastomotic healing were identified using 16S rRNA gene sequencing and were isolated from faecal samples to be tested both in vitro and in vivo. RESULTS: Mice receiving FMT from patients that developed AL displayed poor anastomotic healing. Profiling of gut microbiota of patients and mice after FMT revealed correlations between healing parameters and the relative abundance of Alistipes onderdonkii and Parabacteroides goldsteinii. Oral supplementation with A. onderdonkii resulted in a higher rate of leaks in mice, while gavage with P. goldsteinii improved healing by exerting an anti-inflammatory effect. Patients with AL and mice receiving FMT from AL patients presented upregulation of mucosal MIP-1α, MIP-2, MCP-1 and IL-17A/F before surgery. Retrospective analysis revealed that patients with AL present higher circulating neutrophil and monocyte counts before surgery. CONCLUSION: Gut microbiota plays an important role in surgical colonic healing in patients with CRC. The impact of these findings may extend to a vast array of invasive gastrointestinal procedures.

MT1-MMP Cooperates with TGF-ß Receptor-Mediated Signaling to Trigger SNAIL and Induce Epithelial-to-Mesenchymal-like Transition in U87 Glioblastoma Cells.

Epithelial-to-mesenchymal transition (EMT) recapitulates metastasis and can be induced in vitro through transforming growth factor (TGF)-ß signaling. A role for MMP activity in glioblastoma multiforme has been ascribed to EMT, but the molecular crosstalk between TGF-ß signaling and membrane type 1 MMP (MT1-MMP) remains poorly understood. Here, the expression of common EMT biomarkers, induced through TGF-ß and the MT1-MMP inducer concanavalin A (ConA), was explored using RNA-seq analysis and differential gene arrays in human U87 glioblastoma cells. TGF-ß triggered SNAIL and fibronectin expressions in 2D-adherent and 3D-spheroid U87 glioblastoma cell models. Those inductions were antagonized by the TGF-ß receptor kinase inhibitor galunisertib, the JAK/STAT inhibitors AG490 and tofacitinib, and by the diet-derived epigallocatechin gallate (EGCG). Transient gene silencing of MT1-MMP prevented the induction of SNAIL by ConA and abrogated TGF-ß-induced cell chemotaxis. Moreover, ConA induced STAT3 and Src phosphorylation, suggesting these pathways to be involved in the MT1-MMP-mediated signaling axis that led to SNAIL induction. Our findings highlight a new signaling axis linking MT1-MMP to TGF-ß-mediated EMT-like induction in glioblastoma cells, the process of which can be prevented by the diet-derived EGCG.

Improvement of colonic healing and surgical recovery with perioperative supplementation of inulin and galacto-oligosaccharides.

BACKGROUND AND AIMS: Anastomotic leak (AL) is a major complication in colorectal surgery. Recent evidence suggests that the gut microbiota may affect healing and may cause or prevent AL. Butyrate is a beneficial short-chain fatty acid (SCFA) that is produced as a result of bacterial fermentation of dietary oligosaccharides and has been described as beneficial in the maintenance of colonic health. To assess the impact of oligosaccharides on colonic anastomotic healing in mice, we propose to modulate the microbiota with oligosaccharides to increase butyrate production via enhancement of butyrate-producing bacteria and, consequently, improve anastomotic healing in mice. METHODS: Animal experiments were conducted in mice that were subjected to diets supplemented with inulin, galacto-oligosaccharides (GOS) or cellulose, as a control, for two weeks before undergoing a surgical colonic anastomosis. Macroscopic and histological assessment of the anastomosis was performed. Extent of epithelial proliferation was assessed by Ki-67 immunohistochemistry. Gelatin zymography was used to evaluate the extent of matrix metalloproteinase (MMP) hydrolytic activity. RESULTS: Inulin and GOS diets were associated with increased butyrate production and better anastomotic healing. Histological analysis revealed an enhanced mucosal continuity, and this was associated with an increased re-epithelialization of the wound as determined by increased epithelial proliferation. Collagen concentration in peri-anastomotic tissue was higher with inulin and GOS diets and MMP activity, a marker of collagen degradation, was lower with both oligosaccharides. Inulin and GOS diets were further associated with lower bacterial translocation. CONCLUSIONS: Dietary supplementation with inulin and GOS may improve anastomotic healing and reinforce the gut barrier in mice.