Polymorphisms of the interleukin-1 gene family, oral microbial pathogens, and smoking in adult periodontitis

Interleukin (IL)-1alpha IL-1beta, and IL-1ra contribute to regulation of the inflammatory response in periodontal tissues. We aimed to investigate the distribution of polymorphisms in the IL-1 gene family among periodontitis patients and controls, taking into account smoking and microbiology as additional variables. Fifty-three non-smoking and 52 smoking and patients with severe adult periodontitis and 53 controls were genotyped for bi-allelic IL-IB-889, IL-1B(+3954) and a penta-allelic 86-bp VNTR IL-1RN gene polymorphisms. The presence of Porphyromonas gingivalis and Actinobacillus actinomycetemconfitans was established by culture techniques. We found a higher frequency of allele 2 carriage in lL-1A, IL-1B, and IL-1RN in periodontitis patients who were non-smokers and in whom P. gingivalis and A. actinomycetemcomitans could not be detected (42.1% vs.11.3% in controls; P = 0.0068; OR 5.7 95% Cl: 1.6-19.8). Our results provide evidence that polymorphisms in genes of the IL-1 family are associated with severe adult periodontitis in the absence of other risk factors tested in this patient population.