Osteoarthritis Research Today is a free monthly online journal that collates and summarizes the latest research about Osteoarthritis, including details on treatment, symptoms, causes, medication.

Lower density of synovial nerve fibres positive for calcitonin gene-related peptide relative to substance P in rheumatoid arthritis but not in osteoarthritis.

Dirmeier M, Capellino S, Schubert T, Angele P, Anders S, Straub RH

Laboratory of Experimental Rheumatology and Neuroendocrino-Immunology, Department of Internal Medicine I, University Hospital, 93042 Regensburg, Germany.

OBJECTIVES: Sensory nerve fibres (NFs) contain two major neuropeptides, substance P (SP) and calcitonin gene-related peptide (CGRP). The pro-inflammatory role of SP is known, while CGRP has anti-inflammatory activities by inhibiting T helper type 1 cytokines, TNF secretion and leucocyte proliferation. We demonstrated the increase of SP-positive NFs in RA as compared with OA. This study investigated the density of CGRP-positive NFs relative to SP-positive NFs or sympathetic NFs in synovial tissue of patients with RA and OA. METHODS: By immunofluorescent staining of synovial tissue of 25 patients with RA and 35 patients with OA, NFs positive for CGRP, SP and tyrosine hydroxylase (sympathetic NFs) were quantified. RESULTS: Density of CGRP-positive NFs was higher in OA than in RA, and density of SP-positive NFs tended to be higher in RA. In RA patients, comparison of CGRP-positive and SP-positive NFs in the same synovial tissue demonstrated less CGRP-positive than SP-positive NFs. The ratio of CGRP-positive NFs to SP-positive NFs was lower in RA as compared with OA. In OA, but not in RA, density of CGRP-positive NFs positively correlated with density of sympathetic NFs, which is much lower in RA patients. CONCLUSION: The preponderance of SP-positive NFs over CGRP-positive NFs or sympathetic NFs most probably supports the pro-inflammatory process in patients with RA. The reasons for the loss of CGRP in sensory NFs are not known.

Published 13 December 2007 in Rheumatology (Oxford), 47(1): 36-40.
Full-text of this article is available online (may require subscription).

© 2004-2008 Osteoarthritis Research Today. All Rights Reserved.