Stem Cell Related Phenotype of Hepatocyte-Derived Growth Factor Receptor Positive Leukocytes in Blood and Biopsy Samples of Ulcerative Colitis

Abstract

concentration dependent manner (0.01-100 μg/ml; from 93±3 to 78±3% of control values). The level of TLR2 protein expression was not affected by short-term treatment with 10 μg/ ml LTA. Long-term (18 h) TLR2 activation significantly decreased basal pH levels and inhibited NHE1/NHE2 activity (0.01-100 μg/ml; from 92±2 to 79±3% of control values); a significant increase in TLR2 protein expression (113% of control) was observed after longterm treatment with 10 μg/ml LTA. Inhibition of protein kinase A (PKA; with 10 μM H89), inhibition of phospholipase C (PLC; with 3 μM U73,122), and down regulation of protein kinase C (PKC; with 100 nM PDBu for 18h), prevented the shortand long-term TLR2mediated inhibition of NHE1/NHE2 activity. Shortand long-term treatment with LTA (10 μg/ml) produced a significant increase in cAMP levels (142±4% and 117±2% of control values, respectively). An increase in adenylyl cyclase 3 (AC-3) expression was observed after long-term, but not after short-term, exposure to 10 μg/ml LTA (122±7% of control values). Inhibition of NHE1/NHE2 activity was observed after treatment of T84 cells with forskolin (3 μM), db-cAMP (200 μM) or the PLC agonist m-3M3FBS (50 μM). Conclusions: Activation of TLR2 exerts marked inhibition of NHE1/NHE2 activity in intestinal epithelial cells. Transduction mechanisms set into motion during shortand long-term TLR2-mediated inhibition of NHE1/NHE2 activity involves PKA, PLC and PKC. However, shortand longterm TLR2 activation might use different signaling pathways, since involvement of AC-3 was limited to long-term TLR2-mediated inhibition of NHE1/NHE2 activity.