Investigating the percentage of IL-35R+ cells and the expression of IL-35R in pre-clinical type 1 diabetes

Sammanfattning: Introduction: IL-35 is an anti-inflammatory cytokine that is secreted by regulatory B (Breg) and T (Treg) cells, as well as tolerogenic dendritic cells (tolDCs). Previously our group has shown that systemic administration of IL-35 can reverse established type 1 diabetes (T1D) in mouse models, namely in non-obese diabetic (NOD) and multiple low-dose streptozotocin (MLDSTZ) induced diabetes mice. Furthermore, the circulating levels of IL-35 are lowered in patients with T1D compared to healthy individuals. Whether the decreased levels of IL-35 in both patients and diabetic mice are due to an altered expression of IL-35 receptors (IL35R) in T1D is still unclear. Herein, we aimed to study the expression of IL-35R on Breg, Treg cells and tolDC in pre-clinical T1D and characterize these receptors on tolDC. Methods: NOD and MLDSTZ mice were used for determining the expression of IL- 35R. Thymic glands, spleens and pancreatic draining lymph nodes were harvested from mice for immune cell isolation. This was followed by fluorescent flow cytometry analysis of IL- 35R+ cells. Results: The analysis revealed that the proportion of IL-35R+ Breg and Treg cells do not differ between 12-week-old female and male NOD mice. There was an increasing trend for the proportion of IL-35R+ Treg cells in the spleens of STZ-treated mice while the proportion of splenic IL-35R+ Breg cells were decreased in MLDSTZ mice compared with controls. We also observed a reduced expression of the IL-12Rβ2 subunit in the splenic Breg cells of STZtreated mice. Conclusion: Our data illustrate that in the disease condition the expression of IL-35R may be altered. The expression of the receptor needs to be further investigated in clinical samples in order to determine whether similar trends can be observed in humans.