Somatostatin and its analogues are known to have modulatory effects on immune response and their anti-proliferative, anti-angiogenic, and analgesic properties make them attractive candidates for a therapeutic use in immune-mediated diseases, such as rheumatoid arthritis. Here, we demonstrate the ability of the somatostatin analogue octreotide to inhibit interleukin-15 and to increase interleukin-10 production by rheumatoid arthritis fibroblast-like synovial cells maintained in a chronic inflammatory state. We also prove that the inhibitory effect of octreotide on interleukin-15 and tumor necrosis factor-α production depended on the increase in interleukin-10, since neutralizing anti-interleukin-10 antibody was able to partially reverse this inhibition. In addition, our observations suggest an octreotide control on purinergic signaling, with an inhibitory effect on purinergic P2X and P2Y receptors activation. This would have great implications, considering the roles of P2 receptors in the onset of inflammation. Data here reported extend knowledge on the biological action of octreotide and underline its multiple effects on immune response, which could make octreotide an attractive and valid support for the therapy of diseases where several inflammatory mediators are involved, such as rheumatoid arthritis, and in which the simultaneous action on different aspects can be a successful strategy.
Keywords: cytokines; inflammation; octreotide; rheumatoid arthritis; somatostatin analogues; synoviocytes.