Fig 1: Expression and localization of IL-37 in human gingival tissue. a The sketch of five IL-37 isoforms. b PCR products amplified with specific primer pairs to different isoforms of IL-37 cDNA. c The relative mRNA levels of different isoforms of IL-37 in human gingival tissues from sites with periodontitis were quantitated using real time PCR with isoform-specific primers. d The relative mRNA levels of IL-37b (isoform1) in gingival tissues between health and periodontitis (n ≥ 5/group). Data show the mean ± SD. ***p < 0.0001 (unpaired two-tailed Student’s t-test). e The representative level of IL-37 positive staining in epithelial and connective tissue of human gingival tissue from healthy and periodontitis patient using IHC. Scale bar is 200 µm. f The localization of IL-37b and CD138 were determined in serial slides of gingival tissue from periodontitis patient. The localization of IL-37 in human gingival tissue was mainly associated with epithelial and infiltrated plasma cells. The black circles with red number indicate representative region of IL-37 positive staining. A, B represent the low magnification of IL-37 and CD138 staining in human gingival tissue with Scale bar 200 µm. C–F represent the high magnification of two immune cells infiltrated regions in the connective tissue with Scale bar 20 µm. g, h represent the high magnification of epithelial cells layer with Scale bar 20 µm. g IL-37b and CD138 were co-localized in human gingival tissue of periodontitis patient by immunofluorescence using confocal microscope. The results represent CD138 (green), IL-37 (red), DAPI (blue), and bright field (white). The scale bar is 20 µm. Data shown here are representative of three independent experiments