Using CyTOF to dissect the interplay between Type I interferon and autoantibody production in Systemic Lupus Erythematosus

Dr. Joan Wither Senior Scientist, Krembil Research Institute Professor of Medicine and Immunology, University of Toronto Director of STAT (Urgent Assessment) Rheumatology Clinic, Toronto Western Hospital Director of Early Autoimmune Rheumatic Disease Clinic, Toronto Western Hospital

Principal: Dr. Joan Wither

Co-investigators: Dr. David Brooks and Dr. Zahi Touma

Team member: Zoha Faheem

Our findings indicate that examination of IFN-induced proteins in the peripheral blood immune populations by CyTOF is an extremely powerful technique that may provide important insights into the immune mechanisms that lead to flares of disease activity in SLE.

Analysis of IFN-induced proteins by CyTOF was initially was developed for examination of tumor-infiltrating immune cells in cancer-related studies; however, these immune populations differ quite markedly from those that are seen in the peripheral blood during flares of SLE.  Therefore, we extensively modified the analysis to enable examination of the important immune populations in SLE. In addition, based upon our work in mouse models of SLE, we wanted to examine whether some of the key signaling molecules in immune cells were altered in cells that expressed IFN-induced proteins. We also have recently become interested in whether the immune cells that promote flares become activated in places such as the skin, intestine and lung where the immune system interacts with the environment (potentially indicating that there are environmental triggers for flares). Therefore, we added cell markers to the analysis that would allow us to examine whether the immune cells had been in these sites.

The results of our research show that assessing IFN-induced protein expression using CyTOF is a very powerful and efficient means of examining IFN exposure in multiple immune cell populations, which up until now has required very labour intensive and expensive molecular techniques. Therefore, in ongoing experiments, we propose to use this technique to unravel the association between IFN, the type and site of cellular activation, and flares of disease activity. We also plan to use this technique to examine the role of IFN in the transition of asymptomatic ANA positivity, which can predate development of SLE by many years, to symptomatic disease using a unique cohort of patients followed from the pre-clinical phase of their disease to development of symptoms.