Elucidating the Role of Cyclooxygenase-2 in the Pathogenesis of Oral Lichen Planus – An Immunohistochemical Study with Supportive Histochemical Analysis

Abstract

Objective

Oral lichen planus (OLP) is a chronic, inflammatory disorder that affects the oral mucous membrane. During an inflammatory response, several chemokines and cytokines are released by the cells of the immune system. Activation of MMPs, along with mast cell-derived chymase and tryptase, degrades the basement membrane structural proteins, resulting in basement membrane breaks.

Aim

Investigate the association between the COX-2 expressions, presence of intact or degranulating mast cells within the connective tissue and the extent of basement membrane discontinuity in OLP cases.

Methods

The present study included a total of 50 formalin fixed paraffin embedded specimens (FFPE) of histologically confirmed cases of idiopathic oral lichen planus A retrospective cross sectional analysis was carried out to study the epithelial expression of COX-2 by immunohistochemistry and the use of special stains such as toluidine blue and Periodic Acid Schiff (PAS) to study the mast cell count and basement membrane changes in the oral mucosal tissue respectively.

Results

There was a significant (p = 0.03) association between the COX-2 expressions and mast cell count. As the intensity of COX-2 expression increased from mild to moderate or severe, the number of mast cell count almost doubled.

Conclusion

Interaction between up-regulation of COX-2, mast cell and basement membrane sets a vicious cycle which relates to the chronic nature of the disease. Inhibitors of COX-2 may reduce the inflammatory process preceding the immune dysregulation in OLP.

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