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.
Keywords: IL-17F; chronic periodontitis; novel SNP; polymorphism; sub-gingival pathogens.