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P003 C86/CD16 macrophages may act as a source of WNT2b in intestinal tissue from B3 Crohn’s disease patients

D. Ortiz-Masia1,2, J. Cosin-Roger2,3, M. Rodriguez-Antequera1, D. Macias-Ceja3, S. Coll4, P. Salvador4, L. Gisbert-Ferrándiz4, R. Alós5, J. Manyé6, F. Navarro-Vicente7, S. Calatayud2,4, M. D. Barrachina2,4

1Universidad de Valencia, Medicine, Valencia, Spain, 2CIBERehd, Valencia, Spain, 3Fisabio, Valencia, Spain, 4Universidad de Valencia, Pharmacology, Valencia, Spain, 5Hospital de Sagunto, Sagunto, Spain, 6CIBERehd, Badalona, Spain, 7Hospital de Manises, Manises, Spain

Background

Macrophages contribute to fibrosis through the release of different mediators and the pattern of secretion may vary according to their phenotype. The expression of WNT ligands has been related with the macrophage phenotype and strong evidence identifies the WNT signalling pathway as an emerging modulator of fibrosis.

Methods

The aim of the present study was to analyse the pattern of expression of macrophages and the expression of WNT ligands in surgical resections from Crohn’s disease (CD, n = 43) patients which were categorised according to Montreal classification (B2 or B3; unaffected mucosa of patients with colorectal cancer was used as control). mRNA was isolated from intestinal samples and the expression of macrophage markers and WNT2b was analysed by RT-PCR. The number of macrophages positive for the different markers (CD206, CD86, CD16, and WNT2b) was determined by flow cytometry. PBMCS were isolated from healthy donors and treated during 5 days with secretomes, from control, B2 or B3 surgical resections; the mRNA expression of macrophage markers and WNT2b was determined by RT-PCR. Intestinal crypts were isolated from control samples and were incubated for 24 h with WNT2b and the expression of EMT genes was analysed by RT-PCR. HT29 were treated for 7 days with WNT2b or TGFβ1 and immunofluorescence was performed. Results are expressed as mean ± SEM (n ≥ 5). Statistical analysis was performed by ANOVA + Newman–Keuls test. *p < 0.05 significant differences vs. Non-IBD group or vehicle, #p < 0.05 vs. B2-CD group.

Results

The expression of WNT2b was significantly higher in intestinal samples from B3 CD patients (2.3 ± 0.4) than in controls (1.1 ± 0.1) or B2 patients (0.7 ± 0.1). The number of CD16 or CD86-positive macrophages was significantly higher in intestinal tissue from B3 CD patients (69.7 ± 24.4% and 88.8 ± 18.4%, respectively) than in that from B2 CD patients (36.12 ± 5.8% and 30.58 ± 10.9%, respectively). A high percentage of CD16 positive macrophages in intestinal tissue from B3 CD patients were also positive for WNT2b (24.7 ± 8.8%). The mRNA expression of CD16, CD86, and WNT2b was significantly higher in PBMCS treated with B3-secretomes than in those treated with B2- or control secretomes (A). Exogenous administration of WNT2b to intestinal crypts induced the mRNA expression of EMT genes (B). WNT2b and TGFβ1-induced VIMENTIN expression in HT29 cells (C).

Abstract P002 – WNT2b induces EMT. (A and B) Relative mRNA expression vs. β-ACTIN and represented as fold induction vs. vehicle-treated. (C) Images showing VIMENTIN and nuclear staining in HT29 cells.

Conclusion

A macrophage phenotype expressing CD86/CD16 may act as a source of WNT2b in intestinal tissue from CD patients with a penetrating (B3) behaviour. WNT2b induces EMT in intestinal crypts and HT29 cells.