1. Gastroenterology Unit, Internal Medicine Department, University ‘Tor Vergata’ of Rome, 00133 Rome, Italy
2. Blizard Institute of Cell and Molecular Science, Barts and the London School of Medicine and Dentistry, London E1 2AT, U.K.
3. Dermatology Unit, Internal Medicine Department, University ‘Tor Vergata’ of Rome, 00133 Rome, Italy