Salivary MIF is associated with gingival inflammation and periodontopathogens

Abstract

Objectives: Macrophage Migration Inhibitory Factor (MIF) is a hormone-like cytokine and plays an important role in immuno-inflammatory response related to a number of inflammatory diseases and atherosclerosis. This study determined the MIF levels in saliva and its possible association with periodontal conditions and infection patterns of periodontopathogens. Methods: 79 non-smoking Chinese subjects (33 males and 46 females, aged 35-80 years) were recruited from a health screening program at the Department of Medicine, Queen Mary Hospital, Hong Kong. Clinical parameters including plaque, bleeding on probing (BOP), probing depth and attachment loss were recorded. MIF and IL-1b levels in unstimulated saliva were assessed by ELISA. The presence of Porphyromonas gingivalis (P.g.), Prevotella intermedia (P.i.), and Treponema denticola (T.d.) at supragingival plaque, collected from the tooth surfaces with detectable plaque, were analyzed by polymerase chain reaction.

Results: Salivary MIF was detected in each subject with a median of 123.25 ng/ml (10.04-638.22 ng/ml), and it was significantly correlated with IL-1b levels, with the Spearman's rank correlation coefficient of 0.839, p<0.001. Overall, salivary MIF level was correlated to sites% with BOP (r=0.210, p=0.05). In the subjects with combined infection of P.g., P.i., and T.d., a stronger correlation was found (r=0.465, p=0.004), while in those with one, two or no infection of P.g., P.i., and T.d., no significant correlation was found (r=0.102, p=0.555). Binary logistic regression analysis demonstrated that sites% with BOP was related with high MIF levels (odds ratio=17.63, 95% C.I.: 1.2-261.6, P=0.037).

Conclusion: The present study shows the presence of macrophage migration inhibitory factor in saliva, which is associated with gingival inflammation and infection patterns of periodontopathogens in supragingival plaque. Supported by the Hong Kong Research Grants Council (HKU 7518/05M), The University of Hong Kong (CRCG Funds 200507176137 and 200607176038), and the Sun Chieh Yeh Heart Foundation.