Innervation Pattern and Ca2+ Signalling in Labial Salivary Glands of Healthy Individuals and Patients with Primary Sjögren's Syndrome (pSS)

We have characterised the innervation pattern and intracellular Ca2+-signalling in labial salivary glands (LSG) of 16 patients with primary Sjögren's syndrome (pSS) and 27 healthy controls. Numerous immunoreactive nerve fibers (IRF) containing vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase activating peptide (PACAP) were found around acini, ducts and blood vessels. Substance P (SP)-, neuropeptide Y-, tyrosine hydroxylase- and nitric oxide synthase-IRF were mainly surrounding ducts and blood vessels. The majority of pSS patients had inflamed LSG and the presence of focal lymphocytic infiltrates (FI) were more frequent and pronounced as compared with healthy controls. In areas with normal or diffusely inflamed LSG tissue, pSS patients demonstrated the same distribution of IRF as healthy controls with similar histology. However, IRF were absent in central areas of FI both in pSS and age-matched healthy controls. Although all pSS patients had hyposalivation, stimulation with acetylcholine, norepinephrine, phenylephrine, isoproterenol, VIP, PACAP, SP, adenosine 5'-triphosphate and uridine 5'-triphosphate induced the same increase in the intracellular free Ca2+ concentration in LSG acini from both pSS patients and healthy controls, indicating the presence of functional receptor systems in vitro.