IL-10 inhibition of miR-155 in inflammation

Inflammatory disorders including arthritis, inflammatory bowel disease, psoriasis and multiple sclerosis are characterised by the excessive production of pro-inflammatory cytokines resulting in inflammation, tissue damage and chronic pain. In a healthy immune system, the host has developed mechanisms to protect itself from excessive inflammation. One such mechanism is mediated by the anti-inflammatory cytokine IL-10, which primarily acts to limit the production of pro-inflammatory cytokines and antigen presenting capabilities of cells in the innate immune system. Since the discovery of IL-10, much emphasis has been placed on extrapolating its exact mechanism of inhibition with the aim of potentiating its use therapeutically. Significantly, the systemic administration of IL-10 has had success in many animal models of inflammation as well as clinical success in human disorders such as psoriasis and Crohn’s disease. Despite this, major gaps in our knowledge remain which have weakened the expected therapeutic effect for this anti-inflammatory cytokine. Our early studies discovered that in response to innate immune stimulation, IL-10 can potently inhibit miR-155 (McCoy et al., 2010), a miRNA characterised as a promoter of inflammation and found over-expressed in autoimmune pathologies. This finding suggests that the IL-10/miR-155 axis is a novel mechanism utilised by IL-10 to administer its function. In this study, an Affymetrix array was employed to characterise genes regulated by the IL-10/miR-155 axis in bone-marrow derived macrophages. This project proposal aims to characterise the mechanism of IL-10 inhibition on miR-155, as well as understand the functional outcome and significance of this effect by characterising genes regulated by the IL-10/miR-155 axis. Wild-type and miR-155 knockout bone-marrow derived macrophages were stimulated with LPS and LPS+IL-10 in biological duplicate. N=8 total; WT_BMDM LPS (n=2), WT_BMDM LPS_IL10 (n=2), miR155KO_BMDM LPS (n=2), miR55KO_BMDM LPS_IL10 (n=2)