Common Tongue Epithelial Cell Apoptosis And Related Gene Expression Variation Study

ObjectiveGlossocopy is an important diagnosis basis of traditional Chinese medicine, and the research of tongue coating is an important content of it. In recent years, a lot of study revealed that keratinocytes of stratified squamous epithelium such as in skin undergone apoptosis, during the process of proliferation and differentiation from basal layer, prickle cell layer, granular layer to cuticle. The main constitution of the tongue coating namely the tongue mycoderma epithelium is also belong to the stratified squamous epithelium. The aim of the study was to investigate whether apoptosis may contribute to the changes of tongue coating' s thickness and whether certain apoptosis-related genes such as TGF-beta 3, bax, fas, bcl-2 take part in this process, thus to determine the mechanisms of tongue coating' s change.MethodsObjects of observation were divided into four groups namely normal white and thin coating tongue, pathological thin fur, thick fur and peeling fur. Scraping tongue coating with sterilized vegetable sponge, then centrifugalizing, washing and smearing.Terminal deoxynucleotidyl transferase-mediate deoxyuridine triphosphate nick end labeling technique (TUNEL) was used to identify apoptotic nuclei in smears.Smears were examined by in situ hybridization and image analysis for the expression of mRNAs associated with promoting (TGF-beta 3, bax, fas) or preventing (bcl-2) apoptosis.These smears from all the cases also were stained with immunohistochemical technique for the expression of TGF-beat 3, Bax, Fas, and Bcl~2 proteins.ResultsApoptotic changes were seen in all smears by means of the TUNEL method. Apoptotic index of the peeling fur was higher than any of the others, while the thick fur' s is the lowest.The results observed by in situ hybridization and immunohistochemistry revealed that TGF-beta 3, bax mRNAs and proteins expression were significant lower in thick fur as compared with normal control' s .There was a significant increase in bax, fas mRNAs and proteins expression in peeling fur, acccompaning with a significant decrease in TGF-beta 3 expression.ConclusionDuring the process of proliferation and terminal differentiation, some stratified squamous epithelial cells of tongue-coating undergone apoptosis, and there was a certain relationship between the thickness of the tongue coating and the apoptotic index. The higher expression level of bax, fas may contribute to promote the apoptosis process involved in the terminal differentiation program of tongue epidermal keratinocytes.