Functions of the cytokines in relation oral lichen planus-hepatitis C

Lichen planus (LP) is a chronic common mucocutaneous inflammatory disorder of uncertain aetiology. An association between hepatitis C virus (HCV) infection and LP has been recognised, particularly in Italy, Spain and Japan. The pathogenesis of such an association is unclear, but it may be due to cell-mediated cytotoxicity to an epitope shared by HCV and damaged keratinocytes. Recent studies using in situ hybridization suggest that HCV may replicate in the oral mucosa.

The aim of the present study was to examine the oral epithelium of patients with oral LP for evidence of HCV-RNA by polymerase chain reaction (PCR) and to examine the relationship to cytokines including interferon (INF-gamma), interleukins (IL-1, IL-2, IL-4, IL-6, IL-8 , and IL-10), tumour necrosis factor (TNF-alpha) and transforming growth factor (TGFbeta-1).

We selected 100 Italian patients, and divided them into 4 groups. Group A consisted of 25 HCV+ve patients with erosive oral LP. Group B was a control group constituted by 25 healthy HCV -ve subjects with no LP. Group C consisted of 25 HCV-ve patients with oral reticular LP and Group D was made of 25 HCV-ve patients with oral erosive LP. The patients of group A (test group) were submitted to oral biopsy with 2 samples of epithelium, lesional and non-lesional, and a 10 ml peripheral blood sample was taken. The patients of group B (negative control), C and D (comparison groups) were submitted to oral epithelial biopsy and a 10 ml peripheral blood sample was collected. PCR was used to search for HCV-RNA in biopsy material. Cytokines INF-gamma ,IL-1, IL-2, IL-4, IL-6, IL-8 , IL-10 and TNF-alpha and TGFbeta-1 were assayed in serum.

PCR did not detect the viral genome in oral epithelium of the patients with oral LP and HCV+ve (group A), but there was an increase in levels of TNF-alpha and a reduction of IL-1, INF-gamma and IL-8 compared to patients who had oral reticular LP but HCV-ve and to patients who had oral erosive LP but HCV-ve, and compared to negative controls. The results indicate that patients of group A showed a reduction of pro-inflammatory but an increase in immunomodulant cytokines. The results suggest the possibility that HCV exerts an indirect effect, mediated possibly by the induction of cytokines and lymphokines.