Effects of somatostatin and octreotide on cytokine and chemokine production by lipopolysaccharide-activated peripheral blood mononuclear cells.

ABSTRACT

BACKGROUND: Somatostatin plays an important role in the communication between the nervous, endocrine, and immune systems. Although somatostatin or its analogues have been shown to modulate a number of immune functions, their immunomodulatory effects are not uniform and are strongly dependent on the underlying cell system. AIM: The aim of our study was to analyze the immunomodulatory effects of somatostatin and its analogue octreotide on peripheral blood mononuclear cells (PBMC) in vitro. MATERIALS/SUBJECTS:We used lipopolysaccharide-activated cells from normal glucose tolerant (NGT) subjects and from Type 2 diabetes mellitus (T2DM) patients as T2DM is associated with chronic, low-grade inflammation, and measured immune mediator release with multiplex bead-based assays. RESULTS: Our data showed no statistically significant effects on the secretion of the cytokines interleukin (IL)-1beta, IL-6, IL-10, IL-12, interferon-gamma and tumor necrosis factor-alpha as well as the chemokines IL-8 and monocyte chemoattractant protein (MCP)-1, either on PBMC from T2DM patients or on those from NGT controls. However, a trend towards a dose-dependent biphasic effect was observed for IL- 6, IL-10 and MCP-1 with reduced immune mediator levels at low and increased/unaltered levels at higher somatostatin or octreotide concentrations. These observations could not be explained by interference with cell viability or proliferation. CONCLUSIONS: We could not confirm immunomodulatory properties of somatostatin and octreotide on PBMC. Further analyses are necessary to explain the interaction between neuropeptides and the immune system.