IL1R1 and rheumatoid arthritis: When MSCs were used as a treatment, IL-1R gene expression significantly decreased compared to the RA group, in agreement with [1] who found a significant decrease in IL-1β protein expression in joint extracts from CIA mice treated with human adipose-derived (AD) MSCs, suggesting that a decrease in the agonist IL-1β and an increase in the antagonist IL-1Ra may lead to a decrease in the level of IL-R, which is responsible for transmitting the inflammatory effects of interleukin-1 [1,55].