Lubricin in human temporomandibular joint disc. An immunohistochemical study

Aims: To evaluate, immunohistochemically, the presence and distribution of lubricin inhuman temporomandibular joint (TMJ) discs without any degenerative changes, obtainedfrom autopsies, in order to elucidate the TMJ lubrication system and disc tribology.Methods: Immunohistochemistry for lubricin detection was carried out on 34 TMJ discs. Anydisc had signs of degenerative or inflammatory joint disease nor disc were displaced.Sections were incubated with diluted rabbit polyclonal anti-lubricin antibody and scoredaccording to the percentage of lubricin immunopositive cells. Three different TMJ disc tissuecompartments taken from the intermediate zone were analysed, namely: the central regionas well as the temporal (superior) and condylar (inferior) disc surfaces. The Friedman test,was used to compare lubricin at a protein level expression, amongst the regions of discspecimens.Results: Staining was noted within the TMJ disc cell populations in every disc tissue sample,however, the number of disc cells immunolabelled varied according to disc tissue regions.The percentage of immunostained cells, was statistically significant lower in the centralregion than in each disc surface ( p < 0.0001), whilst any statistically significant differencewas found when comparing the two surfaces one another.Conclusions: Lubricin is present in several location of TMJ disc being significantly moreexpressed at disc surfaces than in the central part.