Assessment of Interleukin-33 Gene Variants and Protein Level in Periodontal Disease among Saudi Population

Background: Periodontal disease is an infectious disease that affects the teeth supporting structures and finally may lead to tooth loss. Interleukin-33 (IL-33) is a recently identified member of the IL-1 family and it was reported to have a role in immune response, bone homeostasis and osteoclastogenesis. Objectives: To analyze and correlate the levels of IL-33 in the plasma and the gingival crevicular fluid(GCF) and the intronic single nucleotide polymorphism (rs1929992) in the IL-33 genein a group of Saudi individuals with moderate to severe periodontitis and a healthy control group. Materials and methods: Seventy unrelated individuals with moderate to severe periodontitis and seventy healthy subjects were included in this study. The periodontal status was assessed based on plaque index, probing depth, bleeding on probing and clinical attachment loss. IL-33 levels were estimated in the GCF and plasma in both groups by ELISA. Peripheral blood was utilized for preparation of genomic DNA that was used for genotyping of IL-33 A/G (rs1929992) using polymerase chain reaction followed by restriction endonuclease digestion. Results: IL-33 concentration was higher- but not statistically significant- in the GCF of the periodontitis subjects in comparison with the controls (P > 0.05) while the plasma level was the same in both groups (P > 0.05). For the IL-33 rs1929992 polymorphism, the frequencies of the IL-33 genotypes and alleles were indifferent between the control group and the periodontitis group (P > 0.05). Conclusion: The levels of plasma and GCF of IL-33 could not differentiate between subjects with periodontitis and healthy controls. In addition, the results suggested that IL-33 rs1929992 polymorphism may not have a risk of periodontitis among the Saudis in Makkah environ.