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* = Presenting author

P055 Galectin-3 plays protective roles in intestinal Behçet’s disease

J. H. Kim*1, 2, H. J. Lee1, H. W. Ma1, 2, D. H. Seo1, 2, X. Che1, 2, D. H. Kim1, S. W. Kim1, 2, 3, J. H. Cheon1, 2, 3

1Yonsei University College of Medicine, Department of Internal Medicine and Institute of Gastroenterology, Seoul, South Korea, 2Yonsei University, Brain Korea 21 Plus Project for Medical Science, Seoul, South Korea, 3Severance Biomedical Science Institute, Yonsei University College of Medicine, Seoul, South Korea

Background

Galectin-3(Gal-3) is a β-galactoside-binding protein that regulates cell-cell and cell-extracellular matrix interactions affecting several biological functions. Gal-3 controls immune responses through pathways stimulated by damage-associated molecular or pathogen-associated molecular patterns. In this study, we assessed the expression of Gal-3 and related cytokines in intestinal Behçet’s disease patients’ tissues, colitis-induced mice, and Gal-3 knockdown HT-29 (Gal-3KD) cell lines and figured out the relationship within the decreased expression of Gal-3 in the intestinal tissues and the increased death of the intestinal epithelium.

Methods

Immunohistochemistry (IHC) and quantitative real-time polymerase chain reaction (PCR) (qRT-PCR) were conducted to measure protein and mRNA expression levels, respectively. Mouse colitis was induced by the administration of dextran sodium sulphate (DSS) and 2,4,6-trinitrobenzenesulfonic acid (TNBS). Gal-3KD HT-29 cell lines were established using short-hairpin RNA (shRNA) transfection. Both normal and Gal-3KD HT-29 were introduced with recombinant human tumour necrosis factor alpha (rhTNF-α) or lipopolysaccharide (LPS). Cell death rate was measured using Annexin V/PI staining assay and flow cytometry after rhTNF-α and LPS treatment.

Results

IHC showed that Gal-3 was significantly reduced in the intestinal BD patients and the average score was only about 30% of healthy controls (HC [n = 16] 2.52 ± 9.5 / int BD [n = 15] 0.82 ± 0.7 / p < 0.001). mRNA expression of Gal-3 was also decreased (HC [n = 5] 1.05 ± 0.34 / int BD [n = 10] 0.56 ± 0.1 / p < 0.05). NLRC4 expression was down regulated, and IL1β expression was up regulated. However, Gal3 and Nlrc4 mRNA levels were highly increased in DSS colitis mice colon tissues. The same tendency was observed in murine colon tissues with the TNBS-induced colitis. In case of HT-29 cells, cells lack of Gal-3 showed an aberrant response against rhTNFα. The pretreatment of low dose of recombinant human Gal-3 (rhGal-3) reduced cytokine expression in both control and Gal-3KD cells, whereas Gal-3KD cells were less reactive against LPS. Additionally, pretreatment of rhGal-3 prevented LPS-induced inflammatory condition.

Conclusion

Gal-3 expression was lowered and inflammatory cytokines were down regulated in the colon tissues of intestinal BD patients compared with normal control tissues, whereas Gal-3 were increased in the colon tissues from the colitis-induced mice similar with normal and Gal-3KD HT-29. Collectively, Gal-3 might play a protective role in the intestinal epithelium and the dysregulation of this lectin protein could induce colitis.