082 Fibroblasts promote increased cannabinoid type 2 receptor expression and inflammatory cytokine production in dermatomyositis

Dermatomyositis (DM) is a chronic, systemic autoimmune disease affecting the skin, muscle, and lungs. The activation of CB2R has been shown to reduce several, key proinflammatory cytokines implicated in DM. Our group has previously shown that CB2R expression was significantly increased in DM skin compared to blood, possibly due to increased production of local inflammatory cytokines. CB2R stimulation alleviates inflammatory response by down-regulating the expression of TNF-α, IL31, IFN-γ, and type I interferon expression in the early stage of inflammation, and reducing the infiltrated inflammatory cells. Having more CB2R on inflammatory cells will lead to enhanced effects of a CB2R agonist. We hypothesized that fibroblasts (FBs) in the skin may play an important role in upregulating CB2R on inflammatory cells within the skin. Therefore, we sought to examine the role of FBs in CB2R activation. DM PBMCs, which typically have minimal CB2R expression, were cultured with human FBs. We then utilized multiplexed flow cytometry to further analyze the expression of CB2R and inflammatory cytokines on 12 cell lineages. When comparing PBMCs cultured with and without FBs, cells cultured with FBs had a significant increase in CB2R expression in CD4+ T cells (p<0.0001), monocyte-derived dendritic cells (moDCs) (p<0.0001), classical Monocytes (CM) (p<0.001), and M1 Macrophages (p <0.0001). There was also a significant increase in inflammatory cells cytokines such as IFNβ, IFNγ, ΝFα, IL31 and IL4 in CD4+ T cells, moDCs, CD11c+ myeloid dendritic cells, CM and CD68+ macrophages. These data suggest FBs play a role in increasing CB2R on inflammatory cells, as well as stimulate production of cytokines in DM skin. This suggests that drugs that activate CB2R, leading to downregulation of proinflammatory cytokines, may have enhanced efficacy in the skin due to FB-induced local upregulation of CB2R on inflammatory cells in the skin.