CD40 and diabetic retinopathy: Studies in diabetic transgenic mice that expressed CD40 only in Müller cells demonstrated that the presence of CD40 in these cells is sufficient for upregulation of Icam-1 (also known as Icam1), Tnf-α (also known as Tnf), Il-1β (also known as Il1b), Nos2 and Ccl2 mRNA as well as for the development of diabetic retinopathy characterised by capillary degeneration [5].