title: Gingival crevicular fluid and serum levels of resistin in obese and non-obese subjects with and without periodontitis and association with single nucleotide polymorphism at -420.
abstract: OBJECTIVE
  Resistin is an adipocytokine, which have been studied for its role in insulin resistance and recently in inflammation. The present study was designed to study the gingival crevicular fluid (GCF) and serum levels of resistin in obese and non-obese subjects with and without periodontitis and to further study the association of single-nucleotide polymorphism (SNP) -420 with these levels.
  
  
  METHODS
  A total of 90 subjects were divided based on gingival index (GI), probing pocket depth (PPD), clinical attachment level (CAL), body mass index (BMI) and waist circumference (WC) into: Non-obese healthy (Group 1, n = 30, BMI ≤ 22.9 and WC < 90 for male subjects and < 80 for female subjects, PPD ≤ 3 mm, CAL = 0, GI = 0), non-obese periodontitis (Group 2, n = 30, BMI ≤ 22.9 and WC < 90 for male subjects and < 80 for female subjects, PPD ≥ 5 mm, CAL ≥ 3, GI ≥ 1) and obese periodontitis (Group 3, n = 30, BMI ≥ 25.0 and WC ≥ 90 for male subjects and ≥ 80 for female subjects, PPD ≥ 5 mm, CAL ≥ 3, GI ≥ 1). The GCF and serum levels of resistin were quantified using enzyme-linked immunosorbent assay and compared amongst the study groups. Further, the association of the resistin levels with periodontal inflammation and SNP at -420 was studied.
  
  
  RESULTS
  The mean resistin levels were highest in Group 3 (14.66 ± 5.93 ng/ml and 9.99 ± 7.22 μg/ml), followed by Group 2 (12.34 ± 4.31 ng/ml and 7.47 ± 3.94 μg/ml) and least in Group 1 (7.09 ± 3.34 ng/ml and 6.05 ± 3.61 μg/ml) in serum and GCF respectively. The levels positively correlated with GI, PPD, CAL, BMI, WC and waist-hip ratio (r < 0.6). The SNP at -420 showed that GG genotype was associated with Group 2 and 3 i.e. periodontitis, while CC genotype was associated with periodontal health. The GG genotype was also associated with high serum resistin levels as compared to CC and CG genotypes.
  
  
  CONCLUSIONS
  Resistin levels increased with periodontal inflammation indicating its possible inflammatory role in periodontitis. GG genotype at -420 is associated with increased serum resistin and with periodontal disease. Thus, further research is needed to study GG genotype and increased serum and GCF resistin levels as putative risk factors for periodontal diseases.
authors.affiliation: Department of Periodontics, Government Dental College and Research Institute, Bengaluru, Karnataka, India.
authors.forename: Swati Pradeep
authors.initials: SP
authors.lastname: Patel
authors.affiliation: Department of Periodontics, Government Dental College and Research Institute, Bengaluru, Karnataka, India.
authors.forename: Pradeep Avani
authors.initials: PA
authors.lastname: Raju
keywords: 420; gingival crevicular fluid; obesity; periodontitis; resistin; single nucleotide polymorphism