To investigate the mRNA transcription and protein expression of osteopontin (OPN) and to analyze the possible role of OPN in primary Sjögren's syndrome (pSS).
In this study, 24 patients with pSS were selected and diagnosed according to the American-European Consensus Group criteria. The control group was composed of 14 subjects. Total RNA from labial glands was extracted. The target gene and β-actin acted as templates to perform reverse transcript polymerase chain reaction (RT-PCR). Then mRNA expression of the target gene were semi-quantitated by the OD ratio of the target gene to β-actin bands on gel under densitometry. Immunohistocheical analysis was used to determine the expression of proteins of the target genes in labial glands from patients and healthy control.
In contrast to the control group, the mRNA transcription and protein level of the target genes in labial glands in pSS patients were significantly increased statistically (P<0.05). Spearman and Pearson rank correlation coefficients were used for analyzing the correlation of lymphocytes foci-score (LFS) with OPN expressions, the level of the mRNA transcription (0.407, P=0.049) and protein expression of OPN (0.476, P=0.039) was positively correlated with the LFS. Immunohistochemistry detected that OPN protein was not only mainly expressed in intracytoplasm of the gland duct, but also in infiltrated lymphocytes.
OPN is higher expressed in the basal and surface of labial glands of pSS patients, which may contribute to the destruction of labial glands.