Increased levels of COX-2 in oral lichen planus supports an autoimmune cause of the disease.
BACKGROUND
Oral lichen planus (OLP) is a chronic inflammatory disease for which the pathogenesis is not fully understood. OLP has autoimmune features and auto immunity has been suggested as a potential cause, whereas WHO has classified OLP as a premalignant condition. Association between chronic inflammation and cancer is known and chronic inflammation is one of the characteristics of OLP. A protein connected to inflammation and suggested to be involved in cancer development is cyclooxygenase-2 (COX-2) which can be inhibited by microRNA-26b (miR-26b).


OBJECTIVE
The aim was to map levels of COX-2 and miR-26b in OLP lesions to see if there was any correlation between expression of COX-2 and its regulator miR-26b in OLP.


METHODS
In biopsies from 20 OLP patients and 20 age and gender-matched controls laser- micro dissection of epithelium was performed. Quantitative RT-PCR, immunohistochemistry and Western blot were used in the analysis.


RESULTS
Levels of COX-2 mRNA were significantly higher while levels of miR-26b were significantly lower in OLP lesions compared to controls. Using immunohistochemistry normal oral mucosa samples did not show any expression of COX-2 while OLP samples expressed the protein. No COX-2 protein was detectable with Western blot.


CONCLUSIONS
Increased expression of COX-2 and decreased expression of miR-26b in OLP suggests both to play a role in OLP. COX-2 has been connected to both malignant development and autoimmunity but as malignant development of OLP is quite rare we suggest that the increased levels of COX-2 seen here support an autoimmune cause of the disease.
Department of Odontology, Umeå University, Umeå, Sweden. karin.danielsson@odont.umu.se
K
K
Danielsson
M
M
Ebrahimi
Y B
YB
Wahlin
K
K
Nylander
L
L
Boldrup
D000328:Adult; D000368:Aged; D001327:Autoimmune Diseases / Q000201:enzymology* / Q000209:etiology / Q000276:immunology; D001483:Base Sequence; D015153:Blotting, Western; D051546:Cyclooxygenase 2 / Q000235:genetics / Q000378:metabolism*; D017931:DNA Primers; D005260:Female; D006801:Humans; D017676:Lichen Planus, Oral / Q000201:enzymology* / Q000209:etiology / Q000276:immunology; D008297:Male; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000235:genetics
D017931:DNA Primers; D012333:RNA, Messenger; D051546:Cyclooxygenase 2