We report herein a striking demethylation of CXCR3 in CD4+ T cells in PBC. In addition, we note hyper-methylation of UBE2A and FUNDC2 in CD8+ T cells, as well as in the regulatory sequences on the X chromosome of the CD4+ T cells in patients with PBC. These data reflect an intense abnormal DNA methylation profiling on the X chromosome in PBC lymphoid subpopulations. In conclusion,

and including the DNA demethylation of CXCR3, our results also emphasize a potential role of CXCR3 in the natural history of PBC. Disclosures: The following people have nothing to disclose: Ana Lleo, Ming Zhao, Yixin Tan, Francesca Bernuzzi, selleckchem Bochen Zhu, Qiqun Tan, Tingting Jiang, Lina Tan, Wei Liao, Maria F. Donato, Federica Malinverno, Luca Valenti, Edoardo A. Pulixi,

Pietro Invernizzi, Quiajin Lu, M. Eric Gershwin BACKGROUND AND AIM: The chloride/bicarbonate exchanger (AE2, SLC4A2) generates a “bicarbonate umbrella”, which maintains most bile salts in the deprotonated state and minimizes the pro-apoptotic effect of their protonated, hydrophobic counterpart. In primary biliary cirrhosis (PBC) AE2 is downregulated CDK inhibitor and we have previously demonstrated that knockdown of AE2 sensitized the H69 cholangiocyte cell line not only towards BSIA, but also to etoposide-induced apoptosis (1). Hence, there might be yet another mechanism accounting for the sensitization of Ae2-deficient cholangiocytes towards pro-apoptotic agents. In SSR128129E fibroblasts from Ae2-/- mice we demonstrated that intracellular bicarbonate accumulation increases

expression and activity of sAC, an evolutionarily conserved enzyme that, in contrast to its transmembrane counterpart (tmAC), is activated by bicarbonate and fine-tuned by calcium, but not regulated by G-proteins or forskolin (2). On the basis of these combined results we hypothesized that BSIA in the H69 cholangiocyte cell line is regulated by sAC. METHODS: The immortalized human cholangiocyte cell line H69 was used to examine BSIA with caspase 3/7 activity as readout. Activity of sAC was inhibited with the specific inhibitors KH7 and 2-OH-estradiol. Knockdown was achieved with lentiviral vectors harbouring short hairpin sequences. RESULTS: Apoptosis induced with 750μM chenodeoxycholate (CDC) was inhibited by sAC-inhibitors (by 74% and 84% for 50μM KH7 and 40μM 2-OH-estradiol, respectively). Apoptosis induced with 1mM GCDC (sodium glycochenodeoxycholate) was similarly inhibited by KH7. Chelating intracellular free calcium ([Ca2+]i) with BAPTA reduced CDC-induced apoptosis by 80%, demonstrating that increased [Ca2+]i upon bile salt treatment is necessary for apoptosis to take place. Knockdown of the mitochondrial calcium uniporter, the principal transporter for mitochondrial calcium buffering, sensitized H69 cholangiocytes to CDC- and GCDC-induced apoptosis and this could be reversed by KH7 treatment, suggesting cytosolic sAC instead of mitochondrial sAC is involved.