Molecular expression of adiponectin in human saliva.

Adiponectin (APN) is an adipocyte-specific secretory protein that is highly and specifically expressed in adipose tissue. Serum APN consists of trimers, hexamers, and larger high-molecular-weight (HMW) multimers, and these HMW multimers appear to be of more bioactive forms. Evidence indicates that APN is produced by salivary gland epithelial cells, might be implicated in the regulation of local immune responses. Salivary APN was investigated in 52 healthy individuals. Western blotting under non-reducing conditions revealed that salivary APN consisted predominantly of a super HMW (SHMW) form of APN. In Western blotting, no significant differences were observed in SHMW APN levels in saliva samples with or without occult blood contamination, but non-SHMW APN levels were elevated in the samples with occult blood contamination. In the saliva samples without occult blood contamination, APN levels were significantly elevated in females than in males, in agreement with the results of previous reports for serum samples. In summary, salivary SHMW APN is suggesting a possible promising oral biomarker.