Enhanced P2X7 activity in human fibroblasts from diabetic patients: a possible pathogenetic mechanism for vascular damage in diabetes.
OBJECTIVE
We have investigated expression and function of the P2X7 receptor in fibroblasts from healthy subjects and patients with type 2 diabetes.


RESULTS
Fibroblasts were isolated from skin biopsies. P2X7 receptor expression in both cell populations was measured by functional assays, RT-PCR, fluorescence-activated cell sorter, and immunoblotting. We found that fibroblasts from diabetic subjects are characterized by enhanced P2X7-mediated responses as indicated by increased shape changes, microvesiculation, enhanced fibronectin and interleukin 6 secretion, and accelerated apoptosis. These responses were blocked by preincubation with the P2X blockers KN-62, oxidized ATP, or pyridoxal phosphate-6-azo(benzene-2,4-disulfonic acid). Furthermore, we also found a higher level of spontaneous fibronectin secretion and of apoptosis in fibroblasts from diabetic compared with healthy subjects. Both higher basal level of fibronectin secretion and spontaneous rate of apoptosis were likely attributable to the increased pericellular concentration of ATP because fibroblasts from diabetic subjects released 3x as much ATP into the supernatants compared with fibroblasts from healthy subjects.


CONCLUSIONS
We conclude that fibroblasts from type 2 diabetes patients are characterized by a hyperactive purinergic loop based either on a higher level of ATP release or on increased P2X7 reactivity.
Solini
Anna
A
Department of Internal Medicine, University of Pisa, Italy.
Chiozzi
Paola
P
Morelli
Anna
A
Adinolfi
Elena
E
Rizzo
Roberta
R
Baricordi
Olavio R
OR
Di Virgilio
Francesco
F
D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000244:Adenosine Diphosphate / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D001081:Apyrase / Q000494:pharmacology; D019898:Autocrine Communication; D048430:Cell Shape / Q000187:drug effects; D003570:Cytidine Triphosphate / Q000494:pharmacology; D003924:Diabetes Mellitus, Type 2 / Q000473:pathology*; D003925:Diabetic Angiopathies / Q000209:etiology*; D005347:Fibroblasts / Q000378:metabolism / Q000473:pathology*; D005353:Fibronectins / Q000378:metabolism; D005786:Gene Expression Regulation; D006801:Humans; D015850:Interleukin-6 / Q000378:metabolism; D008564:Membrane Potentials / Q000187:drug effects; D019899:Paracrine Communication; D011732:Pyridoxal Phosphate / Q000031:analogs & derivatives* / Q000494:pharmacology; D018048:Receptors, Purinergic P2 / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D058486:Receptors, Purinergic P2X7; D014530:Uridine Diphosphate / Q000494:pharmacology; D014544:Uridine Triphosphate / Q000494:pharmacology
D005353:Fibronectins; D015850:Interleukin-6; C546468:P2RX7 protein, human; D018048:Receptors, Purinergic P2; D058486:Receptors, Purinergic P2X7; C077792:pyridoxal phosphate-6-azophenyl-2',4'-disulfonic acid; C033901:3'-O-(4-benzoyl)benzoyladenosine 5'-triphosphate; C017199:2',3'-dialdehyde ATP; D014530:Uridine Diphosphate; D011732:Pyridoxal Phosphate; D000244:Adenosine Diphosphate; C063302:KN 62; D003570:Cytidine Triphosphate; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D000255:Adenosine Triphosphate; D001081:Apyrase; D014544:Uridine Triphosphate