IL37 and periodontitis: Interestingly, recently published studies reported that IL-37 can be secreted by a certain subset of plasma cells and suppress osteoclast formation in vitro.233 Clinical data also demonstrated the downregulation of IL-37 in the GCF of chronic periodontitis patients.44 In addition, a large-scale genome-wide association study determined a polymorphism (rs3811046) in the IL-37 locus associated with the high-level expression of IL-1β in GCF.234 All the evidence reported so far shows that IL-37 might be an anti-inflammatory cytokine.