Distinct roles of myeloid and plasmacytoid dendritic cells in systemic lupus erythematosus

Dendritic cells (DCs) constitute a heterogeneous population of professional antigen presenting cells which are the initiators and key regulators for both immunity and tolerance induction. The significance and impact of DC biology in contemporary immunology and medical research is heightened by the award of the 2011 Nobel Prize for Medicine and Physiology to Ralf Steinman for his discovery and subsequent work on the role of DC in adaptive immunity. As a central regulator of immune responses, DCs also play a pivotal role in the pathogenesis of chronic inflammatory autoimmune conditions such as systemic lupus erythematosus (SLE). In this review, we will focus on the respective role of the two major subsets of blood DC, namely myeloid (m)-DC and plasmacytoid (p)-DC, in SLE immunopathogenesis. Accumulating evidence has highlighted pDCs as the culprit for SLE pathogenesis, mainly through type-I interferon production. Latest findings in the field also decipher the mechanisms by which pDCs interact with neutrophils and platelets and contribute to SLE development. The recent surge of interest in studying microRNA regulation in SLE pathogenesis will also be discussed.