Rheumatology Advance Access originally published online on May 8, 2009
Rheumatology 2009 48(7):727-733; doi:10.1093/rheumatology/kep100
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A role for nitric oxide-mediated glandular hypofunction in a non-apoptotic model for Sjögren's syndrome
1School of Dental Sciences, University of Liverpool, Liverpool, UK.
Correspondence to: Peter M. Smith, Edwards Building, School of Dental Sciences, University of Liverpool, Liverpool L693GN, UK. E-mail: petesmif{at}liv.ac.uk
| Abstract |
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Objective. To investigate a role for the inflammatory mediator, nitric oxide (NO) in SS, an autoimmune condition characterized by salivary and lacrimal gland hypofunction resulting from failure of acinar cells to secrete.
Methods. FURA-2 microfluorimetry was used to measure agonist-evoked changes of [Ca2+]i in isolated mouse and human salivary acinar cells following exposure to NO donors.
Results. NO had a biphasic effect on salivary acinar function. Acute exposure to NO (2 min) caused a cyclic guanosine monophosphate (GMP)-dependent, 1-H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-sensitive increase in the Ca2+ signal elicited in response to acetylcholine (ACh) stimulation, consistent with stimulation of ryanodine receptors by cyclic adenosine diphosphate ribose. Prolonged exposure to NO (>40 min) significantly reduced the ACh-evoked Ca2+ signal by a mechanism independent of cyclic GMP. We found no differences between the responses of human and mouse acinar cells.
Conclusion. Our data show that chronic exposure to NO, which is known to be elevated in SS, could have a role in salivary gland hypofunction. We note a similarity in the response to stimulation of salivary acinar exposed to NO and that which we have previously reported in salivary acinar cells isolated from patients with SS. We speculate that NO-mediated nitrosylation of one or more elements of the signal transduction pathway could underlie down-regulation of salivary function in SS.
KEY WORDS: Sjögren's syndrome, Autoimmune, Nitric oxide, Salivary, Secretion, Ca2+
Submitted 10 December 2008;
revised version accepted 26 March 2009.
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