Screening of interleukin 17F gene polymorphisms and eight subgingival pathogens in chronic periodontitis in Libyan patients

Background: Chronic periodontitis (CP) is triggered by periodontal pathogens influenced by genetic and environmental factors. Recent studies have suggested that anti-inflammatory cytokines such as interleukin 17 (IL−17) play a prominent role in the pathogenesis of CP. Aim: This study aimed to investigate the association between eight sub-gingival pathogens and interleukin 17F (IL−17F) gene single nucleotide polymorphisms with CP among Libyans. Materials and Methods: A case–control study was conducted on 100 individuals between the ages of 25–65 years. Species-specific 16S rRNA primers for each pathogen were used in a multiplex PCR reaction to detect sub-gingival pathogens from a paper point sample. DNA was also extracted from buccal swab samples and IL−17F polymorphisms were detected by Sanger sequencing. Results: A highly significant association between the seven sub-gingival pathogens and CP, (p-value 0.0001) and a high prevalence of P. intermedia (100%), T. forsythia (96%), T. denticola and E. corrodens (92%), P. gingivalis (82%), C. rectus (74%), P. nigrescens (72%), A. actinomvcetcmcomitans (40%) were found in the case group compared with control group. A novel variant in the c. *34 G>A in IL−17F gene caused a change in glutamic amino acid to lysine amino acid, position on chromosome number (6) in the third exon, mRNA/genomic position 597, found in 14.6% of CP patients (p-value = 0.010) while the IL−17F (rs763780) SNP showed no association with CP (p-value = 0.334). Conclusion: P. intermedia appear as keystone pathogen for CP in the Libyan population. A novel variant in the IL−7F gene may be related to the severity of CP.