Somatostatin analogue treatment attenuates histological findings of inflammation and increases mRNA expression of interleukin-1 beta in the articular tissues of rats with ongoing adjuvant-induced arthritis

Objective: Somatostatin is a neuropeptide with modulatory effects on the immune system and the function of synovial cells; it has antiangiogenic and antiproliferative properties. This study aimed to evaluate the clinical, histological, and articular tissue cytokine mRNA response to somostatin treatment in rat adjuvant-induced arthritis (AIA). Methods: Adjuvant-induced arthritis was induced in a total of 68 Lewis rats by immunization with complete Freund's adjuvant. Twenty-four rats were treated with a long-acting somostatin analogue 14 days after disease induction. Twenty-four untreated rats served as controls. The severity of arthritis was scored weekly for 42 days. In a second experiment, 20 rats (ten treated, ten controls) were killed 21 days after treatment for assessment of joint histopathology and articular tissue cytokine mRNA expression. Results: Somatostatin analogue treatment significantly reduced histological scores of early inflammatory changes and increased articular tissue mRNA expression of interleukin-1 beta (IL-1β). A trend toward improvement in physical scores of joint inflammation was seen in the treated group. Late destructive changes were not significantly different. Conclusion: Treatment with a somostatin analogue attenuated early inflammatory changes in AIA joints and increased mRNA expression of IL-1β in the articular tissues of rats with ongoing arthritis. Improvement in the physical findings of joint inflammation was mild.