The purinergic system in allotransplantation.

The purine nucleotide adenosine triphosphate (ATP) is a universal source of energy for any intracellular reaction. Under specific physiological or pathological conditions, ATP can be released into extracellular spaces, where it binds and activates the purinergic receptors system (i.e. P2X, P2Y and P1 receptors). Extracellular ATP (eATP) binds to P2X or P2Y receptors in immune cells, where it mediates proliferation, chemotaxis, cytokine release, antigen presentation and cytotoxicity. eATP is then hydrolyzed by ectonucleotidases into adenosine diphosphate (ADP), which activates P2Y receptors. Ectonucleotidases also hydrolyze ADP to adenosine monophosphate and adenosine, which binds P1 receptors. In contrast to P2X and P2Y receptors, P1 receptors exert mainly an inhibitory effect on the immune response. In transplantation, a prominent role has been demonstrated for the eATP/P2X7R axis; the targeting of this pathway in fact is associated with long-term graft function and reduced graft versus host disease severity in murine models. Novel P2X receptor inhibitors are available for clinical use and are under assessment as immunomodulatory agents. In this review, we will focus on the relevance of the purinergic system and on the potential benefits of targeting this system in allograft rejection and tolerance.

[Integrin Beta 3 PlA1/PlA2 polimorphism does not contribute to complications in both type 1 and type 2 diabetes]. / Il polimorfismo PlA1/PlA2 dell'integrina Beta 3 non contribuisce al rischio di complicanze micro- e macrovascolari nel diabete tipo 1 e tipo 2.

BACKGROUND: The glycoprotein IIIa (beta3 integrin) is an integral part of two glicoprotein receptors of platelets and, respectively, endothelium and vascular smooth muscle cells. The gene encoding the GPIIIa, a receptor for fibrinogen, vWF and fibronectin, shows polymorphism (PlA1/PlA2); the PlA2 allele has been associated with myocardial infarction, stroke and cardiovascular disease. METHODS: Seven hundred and thirty-two subjects with type 1 diabetes and 605 subjects with type 2 were recruited. The prevalence of complications in type 1 diabetes was: microalbuminuria (uA) 17%, overt nephropathy (MA) 10%; background retinopathy (bR) 27%, proliferative retinopathy (pR) 22%; hypertension (HYP) 13%; coronary heart disease (CHD) 9%. The respective figures for type 2 diabetes were: uA 34%, MA 21%; bR 38%, pR 18%; HYP 80%; CHD 26%. A 247 bp fragment (exon 2) was amplified by PCR. For the detection of the point mutation CDGE (Constant Denaturing Gel Electrophoresis) after optimum denaturing conditions setting by DGGE (Denaturing Gradient GE) and/or RFLP by NciI digestion were employed. RESULTS: In type 1 diabetes, PlA1PlA1/PlA1PlA2 distribution was 77/23%. No differences were found among normoalbuminuric (nA: 76/24%), microalbuminuric (uA: 79/21%) and macroalbuminuric subjects (MA: 75/25%, p=0.79) as well as among subjects with no retinopathy (Ret-) (74/26%), bR (76/24%) and pR (78/22%, p=0.81), and between HYP- (78/22%) and HYP+ (72/28%, p=0.27) as well as CHD- (76/24%) and CHD+ (75/25%, p=0.72). Systolic blood pressure, HbA1c and retinopathy were independent predictors of nephropathy. No contribution of diastolic BP, sex, BMI, duration of diabetes and PlA2 allele was found for the risk of nephropathy. In type 2 diabetes, PlA1PlA1/PlA1PlA2/PlA2PlA2 distribution was 74.4/23.3/2.3%, with no differences foud among nA (73/25/2%), uA (75/23/2%) and MA (81/17/2%, p=0.66). No significant difference was detected among subjects with Ret- (74/22/4%), bR (77/22/1%) and pR (77/22/1%, p=0.62). Also, no differences were found between HYP- (81/17/2%) and HYP+ (74/24/2%, p=0.28) as well CHD- (76/22/2%) and CHD+ (74/24/2%, p=0.93). Systolic BP, HbA1c, presence of retinopathy, gender and BMI were independent predictors of nephropathy. Diastolic BP, duration of diabetes and PlA2 allele did not contribute to the risk of nephropathy. CONCLUSIONS: The PlA1/PlA2 polymorphism of the GPIIIa gene does not contribute to the development of nephropathy or retinopathy in type 1 and type 2 diabetes. Furthermore, no association was found between the PlA1/PlA2 polymorphism, hypertension, and coronary heart disease.