Modulation of Transglutaminase 2 expression in the human intestinal mucosa

BAYARDO M; ALLEGRETTI Y; RUMBO M; CHIRDO FG

Rio de Janeiro, Brasil

Congreso; XIII International Congress of Immunology; 2007

IUIS

<!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman"; mso-ansi-language:EN-GB;} p.MsoBodyText, li.MsoBodyText, div.MsoBodyText {margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:14.0pt; mso-bidi-font-size:10.0pt; font-family:Arial; mso-fareast-font-family:"Times New Roman"; mso-bidi-font-family:"Times New Roman"; layout-grid-mode:line;} p.MsoBodyText2, li.MsoBodyText2, div.MsoBodyText2 {margin:0cm; margin-bottom:.0001pt; text-align:justify; mso-pagination:widow-orphan; font-size:10.0pt; font-family:Arial; mso-fareast-font-family:"Times New Roman"; mso-bidi-font-family:"Times New Roman"; mso-ansi-language:ES-MX;} @page Section1 {size:612.0pt 792.0pt; margin:70.85pt 3.0cm 70.85pt 3.0cm; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> Transglutaminase 2 (TG2) participates in diverse biological processes such as wound healing, signalling, cell differentiation and apoptosis. TG2 is upregulated in the intestinal mucosa in active coeliac patients being involved in its pathogenic mechanism in which Th1 cytokines (mainly gIFN) are the hallmark. Stimuli modulating TG2 expression in the epithelium are not yet fully elucidated. Caco-2 and HT-29 cells, human intestinal epithelial cell lines commonly used as a model for enterocytes, were incubated for 24 h with different cytokines. The total RNA was collected and TG2 mRNA levels were determined by quantitative PCR. gIFN produced 4,5 fold increase of TG2 expression in both Caco-2 and HT-29 cells. TNFa produced 2,6 fold increase in HT-29 and lower response in Caco-2 cells. A synergic upregulation was observed when Caco-2 cells were incubated with TNFa and gIFN. In HT-29 cells, IL-1 produced 2,8 fold increase, while a slight increase in TG2 mRNA levels was observed in Caco-2 cells. IL-6 and TGFb, tested in HT-29 cells, produced 2,5 fold increase. In all cases analysed, HT-29 showed a higher response than Caco-2 cells. TG2 protein was detected by Western blot analysis in samples from stimulated cells but relevant differences among treatments were not observed. We cloned the TG2 promoter which showed several putative binding sites for different nuclear factors such as SP1, AP-1, NFkB, which may explain the complex regulatory pathways involved in TG2 expression. In conclusion, TG2 was strongly induced in Caco-2 and HT-29 cells by gIFN, cytokine which may act as the main TG2 inducer in the damaged intestinal tissue.