Aquaporin Locus Contributes to Susceptibility of Periodontitis Associated with Arthritis

Objectives: Aquaporins are water channel proteins that allow permeation of water and glycerol in the lipid bilayer. Aquaporin genes have tissue specificity and can be involved in different pathologies. Periodontitis, arthritis and temporomandibular dysfunction (TMD) are chronic diseases triggered by different causalities, however inflammation is a common mechanism in these three conditions. This study addresses the hypothesis that arthritis, periodontitis and temporomandibular dysfunction can be influenced by variation in aquaporin genes.
Methods: Samples of 664 individuals were obtained from the Dental Registry and DNA Repository project at the University of Pittsburgh. Ten polymorphisms in four aquaporin genes were genotyped by TaqMan chemistry. The analyses were performed using the software PLINK with an alfa of 0.05. In addition, we performed combined analyses for the three phenotypes.
Results: Associations were found between rs467323 in AQP2 and TMD in the recessive (p=0.02) and genotypic models (p=0.03) as well as rs3759129 in AQP2 and periodontitis in the recessive (p=0.03) and genotypic models (p=0.04) (Table 1). When combining patients that had arthritis, periodontitis and TMD, a marker in AQP5 (rs3759129) was associated (p=0.002) and other associations were found when only two phenotypes were analyzed in combination (Table 2).
Conclusions: Our results suggest that aquaporin 2 and 5 play important roles in the pathogenesis of inflammatory conditions such as arthritis, periodontitis and TMD and these results support previous studies suggesting that having periodontitis might increase the risk of having arthritis.