Expression of type I and type III collagens in oral submucous fibrosis: An immunohistochemical study

Background: Oral submucous fibrosis (OSMF) is a potentially malignant collagen - metabolic disorder linked to consumption of betel quid and areca nut. The deposition of collagen and its major subtypes have been the subject of intense scrutiny in the etiopathogenesis of the disorder. Aims and Objectives: The present study was planned to immunohistochemically identify the expression of collagens I and III (COL I and III) in different grades of OSF and compare it with normal oral mucosa and scar tissue. Materials and Methods: Archival paraffin sections of 72 cases of various grades of OSMF, ten cases of normal mucosa as controls and four cases of scar tissue were stained with antibodies to COL I and III (BioGenex Laboratories, CA, USA) to evaluate the collagen subtypes on paraffin sections. The expression was quantified by image analysis software (Jenoptik Optical System, ProgRes ® Capture Pro, version 2.8.8) and statistically analyzed. Results: COL I and III stained all the tissues ubiquitously. COL I was more in ratio and quantity in all the grades of OSMF, normal mucosa, and scar tissue. The proportion of COL I to COL III seemed to increase with progressive grades of OSF. Interestingly, during the process of fibrosis COL III seems to be deposited earlier and gradually replaced by COL I resulting in a skewed ratio vis a vis normal oral mucosa and scar tissue. Conclusions: COL I expression was found to be proportionate with advancing grades of OSF while COL III expression increased in Grade I but subsequently decreased as severity of OSF increased. The increase in COL I at the expense of COL III showed a similar pattern in the submucosa while in the deeper muscle only Grade III cases reflected the trend. While all cases of OSF revealed excessive expression in comparison with normal oral mucosa, the comparison with scar tissue was variable