Comparative proteomic tissue analysis in patients with ossification of the posterior longitudinal ligament

The ossification of the posterior longitudinal ligament (OPLL) involves the ligament that lines the posterior surface of the spinal vertebral bodies. Hormonal and metabolic factors as well as hereditary factors have been proposed to be involved in pathologic ligamentous OPLL. However, there are currently no definitive serological biomarkers for OPLL that might be used to achieve a more convenient and economic diagnosis. To find an easier and simpler diagnostic method and to identify pathogenic proteins associated with OPLL, we assessed PLL tissues from patients with OPLL for proteomic alterations.

OPLL tissues were collected from 12 patients with OPLL, and non-OPLL tissues were collected from 12 healthy subjects without OPLL. To minimize individual variations, we matched the sex and age of the patients in the healthy and OPLL groups. The two-dimensional electrophoresis patterns of tissue from 12 OPLL patients and 12 healthy subjects were compared.

We found 25 proteins that were significantly and consistently different on the two-dimensional electrophoresis gels between the group of ossified PLL tissues from the patients with OPLL and the group of nonossified PLL tissues from the healthy subjects. Among them, 21 proteins were up-regulated in the patients with OPLL, whereas the remaining four proteins were down-regulated.

The information obtained via this proteomic analysis will be very useful in understanding the pathophysiology of OPLL as well as in finding protein candidates to serve as new diagnostic biomarkers of OPLL.