J Rheumatol
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The innervation of normal and rheumatoid human synovium was studied by immunofluorescence microscopy. Antibodies against the general neuronal marker protein gene product (PGP) 9.5 and specific neuropeptides were used. We observed sensory nerves containing substance P (SP) and calcitonin gene related peptide (CGRP) as well as autonomic sympathetic fibers immunoreactive for neuropeptide tyrosine (NPY), its C terminal peptide (C-PON) and the catecholamine synthesizing enzyme tyrosine hydroxylase (TH). ⋯ Quantification of immunostained nerves revealed a significantly decreased innervation of rheumatoid synovia. The densities of both PGP 9.5 and neuropeptide containing nerves were lower in all rheumatoid samples. Our results are compatible with a local release of neuropeptides into joint fluid and point to a disturbed neuronal control of rheumatoid synovial tissue.