Cell receptor-ligand interaction, signalling, activation and apoptosis: 21. Pregnenolone Sulphate is Similar to Dexamethasone in Supressing the Unfettered Secretion of Hyaluronan: In Vitro Study on Cultured Synovial Fibroblasts from Patients with Longstanding Rheumatoid Arthritis (2011)

Background: More than 50 years ago pregnenolone sulphate was used as a symptomatic treatment for inflammatory arthritis with variable results. This “mother-hormone” is considered to have anti-inflammatory properties and almost no side-effects comparing to other steroids. The purpose of our study was to investigate the molecular mechanisms of pregnenolone sulphate effect on cultured synoviocytes obtained from patients with longstanding rheumatoid arthritis (RA).Calcium-permeable channels are known to have roles in many mammalian cell types but the expression and contribution of such ion channels in synovial cells is mostly unknown. The objective of this study was to investigate the potential relevance of Transient Receptor Potential Melastatin 3 (TRPM3) channel to fibroblast-like synoviocytes (FLSs) of patients with rheumatoid arthritis. Methods: Synovial biopsies have been obtained from patients with long-standing RA treated with conventional DMARDs and steroids, which underwent surgical interventions for joint replacements. The study used RT-PCR and immunofluorescence to detect mRNA and protein. Intracellular calcium measurement detected channel activity in a FLS cell-line and primary cultures of FLSs from patients with RA. Enzyme-linked immunosorbent assays measured hyaluronan. Results: Endogenous expression of TRPM3 was detected. Previously reported stimulators of TRPM3 sphingosine and pregnenolone sulphate evoked sustained elevation of intracellular calcium in FLSs. Blocking antibody targeted to TRPM3 inhibited sustained sphingosine and pregnenolone sulphate responses. Secretion of hyaluronan, which contributes adversely in RA, was suppressed by pregnenolone sulphate in FLSs from patients and the effect was blocked by anti-TRPM3 antibody. The magnitude of the effect was comparable with that of Dexamethasone used at pharmacological concentrations. Conclusions: The data suggest that FLSs of patients with RA express TRPM3-containing ion channels that couple negatively to hyaluronan secretion and can be stimulated by pharmacological concentrations of pregnenolone sulphate. This is the first study attempting to explain the mechanism of molecular effects of pregnenolone sulphate on FLSs obtained from patients with severe RA undergoing joint replacements. In vitro, the effect of pregnenolone sulphate in suppressing the unfettered hyaluronan secretion of rheumatoid FLSs, was comparable with that elicited by therapeutic concentration of Dexamethasone. Disclosure statement: D.B. has received a research grant from the Wellcome Trust. C.C. has received a research grant from the Physiological Society. Y.M. has received research grants from the Wellcome Trust and Physiological Society. J.N. has received a research grant from the Wellcome Trust. P.S. has received a research grant from the ORS and University PhD Student Awards. All other authors have declared no conflicts of interest.