Extracellular adenosine 5'-triphosphate modulates interleukin-6 production by human thyrocytes through functional purinergic P2 receptors.
We investigated the presence of P2 receptors (P2Rs) in human thyrocytes and their possible involvement in the modulation of cytokine release. P2Rs expression was assessed by RT-PCR and, when possible, by immunoblotting. Human primary thyrocytes express the mRNA for the following P2X and P2Y subtypes: P2X(3), P2X(5), P2X(6), P2X(7), and P2Y(1), P2Y(2), P2Y(4), and P2Y(11). Stimulation with extracellular nucleotides of fura-2-loaded thyrocytes triggered an intracellular Ca(2+) signal, suggesting expression of functional receptors. Thyrocytes spontaneously released the proinflammatory cytokine IL-6. The ATP-hydrolyzing enzyme apyrase reduced basal IL-6 release, whereas extracellular ATP dose-dependently increased IL-6 secretion. Uridine 5'-triphosphate was also an effective stimulus, whereas benzoyl-ATP was ineffective, suggesting a P2Y- rather than P2X-modulated response. Finally, TSH reduced both the intracellular Ca(2+) ([Ca(2+)](i)) rise and IL-6 release triggered by P2Rs stimulation. In conclusion, we provide functional, pharmacological, and biochemical evidence that human primary thyrocytes express P2YR and P2XR subtypes, coupled to increases in ([Ca(2+)](i)) and secretion of IL-6. P2R-dependent modulation of IL-6 release from human thyrocytes suggests a novel mechanism whereby an inflammatory and/or immune-mediated damage can be initiated and amplified in the thyroid.
Caraccio
Nadia
N
Department of Internal Medicine, University of Pisa, Via Roma 67, I-56100 Pisa. Italy.
Monzani
Fabio
F
Santini
Eleonora
E
Cuccato
Sabina
S
Ferrari
Davide
D
Callegari
Maria Giulia
MG
Gulinelli
Sara
S
Pizzirani
Cinzia
C
Di Virgilio
Francesco
F
Ferrannini
Ele
E
Solini
Anna
A
D000255:Adenosine Triphosphate / Q000494:pharmacology / Q000502:physiology*; D019898:Autocrine Communication; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D045604:Extracellular Fluid / Q000378:metabolism*; D006801:Humans; D015850:Interleukin-6 / Q000096:biosynthesis* / Q000378:metabolism; D007425:Intracellular Membranes / Q000378:metabolism; D009994:Osmolar Concentration; D012333:RNA, Messenger / Q000378:metabolism; D018048:Receptors, Purinergic P2 / Q000235:genetics / Q000502:physiology*; D013961:Thyroid Gland / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D013997:Time Factors; D014544:Uridine Triphosphate / Q000494:pharmacology
D015850:Interleukin-6; D012333:RNA, Messenger; D018048:Receptors, Purinergic P2; D000255:Adenosine Triphosphate; D002118:Calcium; D014544:Uridine Triphosphate