Objectives: Interleukin-10 (IL-10) is an immunoregulatory cytokine that has a central role in suppressing proinflammatory responses. Patients with deleterious mutations in interleukin (IL)-10 or IL-10 receptor (IL-10R) genes develop severe colitis and perianal disease in the first months of life. Whether IL-10R expression and signaling in pediatric- or adult-onset Crohn disease (CD) are altered is unknown. The objective of this study was to characterize IL-10R expression and IL-10R-mediated suppression in patients with CD.
Methods: Monocytes were sorted from peripheral blood mononuclear cells of patients with CD and control subjects. IL-10R expression was determined by flow cytometry. Monocytes were stimulated with lipopolysaccharide (LPS) for 3 hours in the presence of different concentrations of IL-10 to determine IL-10-mediated suppression of tumor necrosis factor α production. Signaling through the IL-10R was evaluated by quantifying STAT3 phosphorylation in response to IL-10 stimulation.
Results: Forty-two subjects were enrolled in this study: 19 with CD and 23 controls. Stimulation of monocytes with LPS markedly increased IL-10R expression in both groups but to a much lower extent in patients with CD. In addition, IL-10-mediated suppression of TNFα production upon LPS stimulation and IL-10-induced STAT3 phosphorylation were attenuated in patients with CD versus controls. Finally, LPS-stimulated monocytes from patients with CD secreted significantly lower quantities of IL-10, compared with control monocytes.
Conclusions: IL-10R expression and signaling are decreased in monocytes from patients with CD. Additional studies are required to assess whether similar patterns occur in other innate immune cells, especially in the gut, and whether disease activity, medical therapy, and genetic factors modulate these findings.