Objectives: Rheumatic diseases are chronic systemic autoimmune inflammatory diseases. However, the etiology of many rheumatic diseases remain unknown. Microparticles (MPs) are complex structures composed of a lipid bilayer that contain transmembrane proteins and enclose soluble hydrophilic components derived from the cytosol of a donor cell, including deoxyribonucleic acids, ribonucleic acids or nucleus proteins themselves. Plasmacytoid dendritic cells (pDCs) play an important role in innate inflammation in rheumatic diseases. The aim of this study was to assess the reaction of pDCs by stimulating them with MPs in a model of rheumatic disease.
Methods: Human submandibular gland cells were treated with tumor necrosis factor-alpha, tamoxifen and cyclohexamide to induce apoptosis. MPs and apoptotic bodies (ABs) were collected by centrifugation into pellets. Pellet 1 was ABs-rich (P1), pellet 2 was both ABs- and MPs-rich (P2), and pellet 3 was MPs-rich (P3). The expression of Toll-like receptor (TLR) 7 and TLR9 on a pDC cell line (GEN 2.2) were measured by quantitative reverse transcription polymerase chain reaction after the cells were stimulated by P1, P2 and P3, respectively.
Results: The expression of TLR7 and TLR9 on pDCs was 2.0 and 4.1 times increased by P1 stimulation, unchanged and 1.5 times increased by P2 stimulation, and 2.4 and 3.8 times increased by P3 stimulation, respectively, compared to a non-stimulation group.
Conclusion: MPs and ABs can induce the expression of TLR7 and TLR9 on pDCs. MPs and ABs may play a role in the onset and maintenance of rheumatic disease via TLR pathways.
