Immunopathogenesis of oral lichen planus

Accumulation of oligoclonal T cells in the infiltrating lymphocytes in oral lichen planus

BACKGROUND

Identification of a disease-specific and possibly pathogenic T-cell receptor (TCR) in oral lichen planus (OLP) is one of the most important steps to reveal the pathogenic antigen recognized by the T cells and thereby elucidate the pathogenesis and etiology of OLP.

METHODS

In buccal mucosa biopsy specimens and peripheral blood mononuclear cells (PBMC) from seven patients with OLP, the TCR V beta gene usage was examined by polymerase chain reaction-based and single-strand conformation polymorphism analyses.

RESULTS

The V beta families expressed in the biopsy specimens were markedly heterogeneous, but they were restricted in comparison to those observed in the PBMC. The V beta families predominantly expressed in the biopsy specimens in comparison with the PBMC were still heterogeneous in individual patients and differed from patient to patient; however, V beta 2, V beta 6, and V beta 19 were commonly predominant in the biopsy specimens from more than half of the patients. Among the V beta families predominantly expressed in the biopsy specimens, the accumulation of T-cell clonotypes was observed in the majority of the V beta families including V beta 6 and V beta 19; however, it was not observed in the minority of the V beta families including V beta 2.

CONCLUSIONS

These results suggest that unique T-cell populations bearing V beta 2, V beta 6, or V beta 19 gene products tend to expand in OLP lesions as a consequence of in situ stimulation with a restricted epitope of either a nominal antigen on the MHC molecule for the majority of the V beta families, even if only in minor populations, or of a common superantigen for the minority of the V beta families.

The pathogenesis of oral lichen planus

Both antigen-specific and non-specific mechanisms may be involved in the pathogenesis of oral lichen planus (OLP). Antigen-specific mechanisms in OLP include antigen presentation by basal keratinocytes and antigen-specific keratinocyte killing by CD8(+) cytotoxic T-cells. Non-specific mechanisms include mast cell degranulation and matrix metalloproteinase (MMP) activation in OLP lesions. These mechanisms may combine to cause T-cell accumulation in the superficial lamina propria, basement membrane disruption, intra-epithelial T-cell migration, and keratinocyte apoptosis in OLP. OLP chronicity may be due, in part, to deficient antigen-specific TGF-beta1-mediated immunosuppression. The normal oral mucosa may be an immune privileged site (similar to the eye, testis, and placenta), and breakdown of immune privilege could result in OLP and possibly other autoimmune oral mucosal diseases. Recent findings in mucocutaneous graft-versus-host disease, a clinical and histological correlate of lichen planus, suggest the involvement of TNF-alpha, CD40, Fas, MMPs, and mast cell degranulation in disease pathogenesis. Potential roles for oral Langerhans cells and the regional lymphatics in OLP lesion formation and chronicity are discussed. Carcinogenesis in OLP may be regulated by the integrated signal from various tumor inhibitors (TGF-beta 1, TNF-alpha, IFN-gamma, IL-12) and promoters (MIF, MMP-9). We present our recent data implicating antigen-specific and non-specific mechanisms in the pathogenesis of OLP and propose a unifying hypothesis suggesting that both may be involved in lesion development. The initial event in OLP lesion formation and the factors that determine OLP susceptibility are unknown.

Oral lichen planus: immunohistology of mucosal lesions

BACKGROUND

Current evidence suggests that immunological mechanisms are involved in oral lichen planus (OLP) pathogenesis. The events implicate activated epithelia that comprise antigen-presenting Langerhans cells, immunocompetent keratinocytes and subepithelial inflammatory infiltrate. Also, the presence of a high density of leucocyte cells may occur for the expression of a variety of adhesion molecules. The aim of this study was to analyse the immunoexpression of some adhesion molecules as well as lymphocytic markers in order to determine the disease pathogenesis in a Venezuelan population.

METHODS

The 18 OLP and 10 normal oral mucosa biopsies were immunostained for CD4, CD8, CD1a, LFA-1, VCAM-1 and ICAM-1.

RESULTS

The results showed an increased number of CD4+, CD8+, CD1a+ cells in OLP. Serial sections showed CD4+ and CD8+ cells also expressed LFA-1. The expression of ICAM-1 and VCAM-1 were significantly higher in OLP.

CONCLUSIONS

The immunological reaction begins with Langerhans cells activation, which presents an antigen to CD4+ lymphocytes. Those cells through ICAM-1 and LFA-1 promote epithelial destruction. Afterwards, cytokine production, ICAM-1 and VCAM-1 expression can activate CD8+ lymphocytes leading to the chronic form of the disease.

Mast cell/T cell interactions in oral lichen planus

Lichen planus is a disorder characterized by lesions of the skin and oral mucous membranes. Although many patients have involvement of both skin and oral mucosa at some stage during the progress of the disease, a larger group has oral involvement alone. It has been reported that oral lichen planus (OLP) affects one to two percent of the general population and has the potential for malignant transformation in some cases (1, 2). Like many chronic inflammatory skin diseases, it often persists for many years. Numerous disorders may be associated with OLP such as graft-vs.-host disease and Hepatitis C virus infection (3), however, it is unclear how such diverse influences elicit the disease and indeed whether they are identical to idiopathic OLP. Available evidence supports the view that OLP is a cell-mediated immunological response to an induced antigenic change in the mucosa (4-6). Studies of the immunopathogenesis of OLP aim to provide specific novel treatments as well as contributing to our understanding of other cell-mediated inflammatory diseases. In this paper, the interactions between mast cells and T cells are explored from the standpoint of immune regulation. From these data, a unifying hypothesis for the immunopathogenesis of OLP is then developed and presented.

Langerhans cells and T cells in oral graft versus host disease and oral lichen planus

Chronic graft versus host disease (cGVHD) of the oral mucosa, following allogeneic stem cell transplantation, and oral lichen planus (OLP) are both mucosal diseases where the immune system is involved in the pathogenesis. Although the aetiology of the two conditions is different, they present with a similar clinical appearance. This study compares the two diseases regarding the distribution of cells, which are expressing cell surface markers of interest for inflammatory responses. Monoclonal antibodies (MoAbs) were used in standard immunohistochemical procedures. CD1a+, CD80+ and CD86+ cells in the epithelium of OLP- and cGVHD lesions had the dendritic morphology of Langerhans cells (LC). Higher frequencies of CD1a+ LC as well as CD25+ cells were observed in the OLP epithelium than in the cGVHD epithelium. The OLP lesions showed higher frequencies of subepithelial cells expressing CD1a, CD86, CD4, CD8 and CD25 than the cGVHD lesions. Notably there was a significantly higher frequency of CD25+ cells in the epithelium and the connective tissue of OLP than in cGVHD. These cells might represent regulatory T cells. In conclusion, cGVHD and OLP show marked differences at the cellular level despite similar clinical appearance. Hence, the findings indicate differences in the regulation of the inflammatory response between the two conditions.

Identification of the AgNORs, PCNA and ck16 proteins in oral lichen planus lesions

The expression of proliferating cell nuclear antigen (PCNA), cytokeratin 16 (ck16) and Ag nucleolar organizer regions (AgNORs) were assessed in 20 cases of lichen planus, 20 cases of keratosis and 20 cases of normal oral mucosa in order to evaluate the rate of keratinocyte proliferation in these tissues. Three hundred cells were counted in each sample: 100 basal cells, 100 suprabasal cells and 100 squamous cells. The mean number of AgNORs and the percentage of PCNA positive cells were calculated. Except from similar staining of suprabasal cells of lichen planus and keratosis, PCNA and AgNORs values were higher in all layers of lichen planus than in both keratosis and normal oral mucosa. The three groups showed similar ck16 immunostaining: all of the cells were positive, except those of the basal layer. The results suggest that the keratinocyte proliferation index is higher in lichen planus than in keratosis and normal mucosa. Besides, ck16 should not be used to differentiate the entities studied.

Hypersensitivity of the oral mucosa: clinics and pathology

Hypersensitivity reactions of the oral mucosa comprise an array of clinical manifestations. Some of the reactions are difficult to differentiate from toxic reactions. Hypersensitivity reactions of type I, type III, and type IV are well known, although, especially for types I and III, they are rarely encountered. Type-I reactions are most frequently seen related to application of polymers in the oral cavity, such as orthodontic bonding and fissure sealant materials. There may also be systemic manifestations such as urticaria. Type-IV reactions may be seen related to most dental materials used, from amalgam and gold to polymers. These reactions appear as chronic reddening and/or ulceration of the oral mucosa. Lichenoid reactions have histopathological characteristics compatible with type-IV hypersensitivity reactions and are the most prevalent material-adverse reactions seen in the oral cavity. A special variety inside the lips with multiple papules and/or diffuse redness has recently been identified. This lesion comprises a serious treatment challenge. Skin patch tests, applying a series of dental materials in non-toxic concentrations on the skin, have been used to identify sensitization. However, the value of those tests can be questioned. Exacerbation of geographic stomatitis may be another form of hypersensitivity to dental materials.

Immunohistochemical study of oral lichen planus associated with hepatitis C virus infection, oral lichenoid contact sensitivity reaction and idiopathic oral lichen planus

OBJECTIVES

Oral lichen planus (OLP) is a common mucocutaneous disorder and might be associated to a possible pathogenic relationship with hepatitis C virus (HCV) infection or hypersensitivity to dental alloy. We examined the clinical and immunohistochemical features of OLP associated with HCV infection (OLP-HCV), oral lichenoid contact sensitivity reaction (OLCSR), and idiopathic oral lichen planus (iOLP). The immunohistochemical expressions of CD4, CD8, B cells, Class II major histocompatibility complex antigen (HLA-DR), S-100, HSP60, Proliferating cell nuclear antigen (PCNA) and Ki-67 were compared to study the pathogenic differences of the three OLP groups.

MATERIALS AND METHODS

Three groups of OLP patients, (I) OLP-HCV patients (n = 17), (2) OLCSR patients (n = 10) and (3) iOLP patients (n = 14) were retrieved from clinical records and tissues examined immunohistochemically by the avidin-biotin-complex technique.

RESULTS

The patients with OLP-HCV showed widespread lesions. The proportion of CD8+ cells was found to be significantly higher in the lamina propria of the OLP-HCV patients and a significantly lower proportion of CD8+ cells of the OLCSR patients was noticed in the epithelium or the connective tissue papillae than in the iOLP patients. There were no significant differences in either the number of CD4+ cells or B cells between the three OLP groups. No significant differences in the number of HLA-DR+ cells were found between the three OLP groups and some OLP-HCV patients showed a significant increase of S-100+ cells in the epithelium compared with iOLP patients. There were no significant differences in either the number of PCNA+ or Ki-67+ cells between the groups. The patients showed similar weak expressions of HSP60 in the three OLP groups.

CONCLUSION

The different distributions of the CD8+ cells that could have functionally different roles might be related to the distinct pathogenic mechanisms in the three OLP groups.

Matrix metalloproteinases and their inhibitors in oral lichen planus

BACKGROUND

Oral lichen planus (OLP) is characterized by a sub-epithelial lymphocytic infiltrate, basement membrane (BM) disruption, intra-epithelial T-cell migration and apoptosis of basal keratinocytes. BM damage and T-cell migration in OLP may be mediated by matrix metalloproteinases (MMPs).

METHODS

We examined the distribution, activation and cellular sources of MMPs and their inhibitors (TIMPs) in OLP using immunohistochemistry, ELISA, RT-PCR and zymography.

RESULTS

MMP-2 and -3 were present in the epithelium while MMP-9 was associated with the inflammatory infiltrate. MMP-9 and TIMP-1 secretion by OLP lesional T cells was greater than OLP patient (p < 0.01) and healthy control subject (p < 0.001) peripheral blood T cells. MMP-9 and TIMP-1 mRNA levels were greater in OLP lesional T cells compared with healthy control subject peripheral blood T cells p < 0.01). Tumor necrosis factor (TNF)-alpha upregulated OLP lesional T-cell MMP-9 (not TIMP-1) mRNA and secretion (p < 0.05). The in vitro activation rate of MMP-9 from OLP lesional T cells was greater than that from OLP peripheral blood T cells (p < 0.05).

CONCLUSION

T-cell-derived MMP-9 may be involved in the pathogenesis of OLP. Relative over-expression of MMP-9 (compared with TIMP-1) may cause BM disruption and facilitate intra-epithelial T-cell migration in OLP.

Peripheral T-cell subsets in patients with reticular and atrophic-erosive oral lichen planus

OBJECTIVE

Oral lichen planus (OLP) presents with various clinical forms that can be classified into 2 major types: reticular OLP and atrophic-erosive OLP. Our objective was to investigate immunologic differences between these 2 types.

STUDY DESIGN

We investigated possible immunologic differences between 26 patients with reticular OLP and 26 patients with atrophic-erosive OLP.

RESULTS

No differences were detected in serum Ig levels or complement levels. However, the mean proportions of CD4+CD45RO+ and DR+ lymphocytes were significantly higher in patients with atrophic-erosive OLP than in patients with reticular OLP, whereas the mean proportion of CD8+CD45RA+ lymphocytes was significantly lower in patients with atrophic-erosive OLP.

CONCLUSION

These findings suggest that the 2 clinical types of OLP might have different immunopathogenic mechanisms.

Management of oral lichen planus

Lichen planus is a relatively common disorder of the stratified squamous epithelia. Most dental and medical practitioners see patients with lichen planus, but not all are recognized as having the disease. Patients with lichen planus may have concomitant involvement of the disease in multiple sites. Oral lichen planus lesions usually have a distinctive clinical morphology and characteristic distribution, but oral lichen planus may also present a confusing array of patterns and forms, and other disorders may clinically mimic oral lichen planus. The etiopathogenesis of lichen planus appears to be complex, with interactions between genetic, environmental, and lifestyle factors. Much has now been clarified about the etiopathogenic mechanisms involved and interesting new associations, such as with liver disease, have emerged. The management of lichen planus is still not totally satisfactory in all cases and there is as yet no definitive treatment that results in long term remission, but there have been advances in the control of the condition. Amongst the many treatments available, high potency topical corticosteroids remain the most reliably effective, though topical cyclosporine, topical tacrolimus, or systemic corticosteroids may be indicated in patients whose condition is unresponsive to topical corticosteroids.

The mechanism of mononuclear cell infiltration in oral lichen planus: the role of cytokines released from keratinocytes

To clarify the pathogenesis of oral lichen planus (OLP), we investigated the roles of keratinocytes (KC) in mononuclear cell infiltration. When peripheral blood mononuclear cells (PBMC) obtained from healthy donors were cultured in the presence of culture supernatants of KC separated from the noninflamed gingivae (Nor-KC) and cheek mucosae of patients with OLP (OLP-KC), the number of migrated PBMC across monolayered human umbilical vein endothelial cells (HUVEC) were increased to about 1.3-fold and 1.5-fold of the control level, respectively, with increases of the expression of CD11a, CD11b, CD18, and CD49d on PBMC and intracellular adhesion molecule-1, vascular cell adhesion molecule-1, and endothelial-leukocyte adhesion molecule-1 on HUVEC. The number of migrated PBMC was reduced to about 60% of the control level by pretreatment of PBMC with anti-CD11a or anti-CD18 MAb and reduced to about 70% by pretreatment of HUVEC with anti-CD54 MAb. The pretreatment of PBMC with genistein, H-7, wortmannin, or exoenzyme C3 decreased the migrated PBMC by about 70 to 90%. In agreement with these results, the culture supernatants of OLP-KC up-regulated tyrosine phosphorylation of 62-kDa, 70-kDa, and 102-kDa proteins, phosphatidylinositol-3 kinase, and protein kinase C activities and activated Rho protein level more so than did those of Nor-KC. Additionally, actin reorganization with the formation of membrane ruffles and lamellipodia was distinctly induced by the culture supernatants of OLP-KC. These results indicate that cytokines generated by KC transduce their signals in PBMC, up-regulating the expression of cell surface adhesion molecules and migration activity with reorganization of actin filaments.

The effect of sodium lauryl sulphate, triclosan and zinc on the permeability of normal oral mucosa

OBJECTIVE

Sodium lauryl sulphate (SLS), an important component in many oral health products, is well established as a contact irritant in skin. Recent studies have suggested that it may also affect the structural integrity of oral mucosa. SLS is rarely used alone in dentifrices or mouthwashes and the aim of this study was to establish the effect of SLS both alone and in combination with Triclosan (TCN) and zinc (Zn) on the permeability barrier properties of normal human oral mucosa.

METHOD

Ventral tongue mucosa was obtained from nine males and seven females within 60 h of death and stored frozen at -70 degrees C until use. The permeability of the tissue to tritiated water was measured after pretreatment for 15 min with SLS alone, SLS/TCN, SLS/Zn and a SLS/TCN/Zn mixture. Treatment with distilled water (DW) served as control. The histological appearance of the tissue before and after treatment was also examined by light microscopy.

RESULTS

SLS treatment caused a significant increase in water permeability compared to control tissue (Kp = 11.7 +/- 1.00; 4.96 +/- 0.50 respectively; P < 0.005). Treatment with a SLS/TCN/Zn mixture, however, had no effect on the permeability to water (Kp = 5.5 +/- 0.56). Histological examination revealed that tissue exposed to SLS had a marked disruption of the epithelial surface whilst tissue treated with a SLS/TCN/Zn mixture was indistinguishable from controls.

CONCLUSION

Although mucosa exposed to SLS alone showed an increase in permeability to water, the addition of TCN and Zn to SLS appeared to prevent this effect. As SLS is included in some dental products to solubilise compounds such as TCN, its presence may have no effect on the permeability barrier property of oral mucosa.

Non-plaque-induced gingival lesions

The origin of gingival inflammation is occasionally different from that of routine plaque-associated gingivitis, and such non-plaque-associated types of gingivitis often present characteristic clinical features. Examples of such forms of gingivitis are specific bacterial, viral, and fungal infections. Specific bacterial infections of gingiva may be due to Neisseria gonorrhea, Treponema pallidum, streptococci, and other organisms. The most important viral infections of gingiva are herpes simplex virus type 1 and 2 and varicella-zoster virus. Fungal infections may be caused by several fungi, the most important of these being Candida species including C. albicans, C. glabrata, C. krusei, C. tropicalis, C. parapsilosis, and C. guillermondii. Gingival histoplasmosis is a granulomatous disease caused by the fungus Histoplasma capsulatum and, as for the other specific infections of gingiva, a confirmed diagnosis may require histopathologic examination and/or culture. Atypical gingivitis may also occur as gingival manifestations of dermatological diseases, the most relevant of these being lichen planus, pemphigoid, pemphigus vulgaris, erythema multiforme, and lupus erythematosus. Non-plaque induced gingival inflammation can be caused by allergic reactions to dental restorative materials, toothpastes, mouthwashes, and foods. In addition, gingival inflammation may result from toxic reactions, foreign body reactions, or mechanical and thermal trauma.

Reduced in vivo cell-mediated immune responses to mumps, tuberculin, and streptokinase/streptodornase but not to Candida albicans in oral lichen planus

Oral lichen planus is considered to be a T-cell-mediated disease. The purpose of this study was to investigate the capacity of T-lymphocytes in oral lichen planus patients to respond to a number of commonly encountered environmental antigens in vivo. To do this, we assessed dermal delayed-type hypersensitivity responses to mumps, streptokinase/streptodornase, Candida albicans, and purified protein derivative of tuberculin (PPD) in 17 oral lichen planus patients and in matched controls. Reduced induration in response toward mumps, PPD, and streptokinase/streptodornase was demonstrated in oral lichen planus patients compared with controls. In addition, the total sum of induration diameters was decreased in the patients. However, C. albicans stimulation resulted in similar levels of response in both groups. The differences in induration size between matched patients and controls for mumps and PPD were thus significantly greater than the corresponding differences for the C. albicans antigen. This suggests that a selective difference in the response to these antigens exists in oral lichen planus patients. The results may point to a loss of memory T-helper function to infrequently encountered environmental antigens, represented by mumps, PPD, and streptokinase/streptodornase, contrarily to memory function to common antigens (C. albicans), which seem to be unaffected.

LFA-3 (CD58) mediates T-lymphocyte adhesion in chronic inflammatory infiltrates

Previous studies have suggested that LFA-3 has an important role in a number of chronic inflammatory pathologies, although an active role for LFA-3 within in vivo inflammatory reactions has not previously been directly observed in humans. To assess the importance of LFA-3 in this process, this study used an adaptation of the Stamper-Woodruff lymphocyte adhesion assay to measure the binding of exogenous activated lymphocytes to the T-cell-dominated chronic inflammatory infiltrate of oral lichen planus. Antibody blockade experiments showed that anti-LFA-3 monoclonal antibody reduced lymphocyte adhesion by approximately 29%, while anti-ICAM-1 produced a reduction of 26%. These results thus suggest that both LFA-3 and ICAM-1 are likely to mediate cell-cell interactions within lesional tissues in vivo. Moreover, these findings are also the first to directly demonstrate that LFA-3-mediated adhesion, like that of ICAM-1, is functionally important in the molecular pathology of inflammatory mucosal disease.

Elevated production of salivary nitric oxide in oral mucosal diseases

Nitric oxide (NO) is known to play an important role in biological systems. In this study, we measured levels of NO in the saliva of 39 patients with oral mucosal diseases: 21 had oral lichen planus (OLP) and 18 had recurrent aphthous ulceration (RAU). NO was assayed using the Griess reagent, which measures nitrite (NO2), the byproduct of NO. NO2 was detected in all tested samples, and levels in the saliva of patients were significantly increased relative to those of healthy subjects. We also examined the effect of NO on fibroblasts, keratinocytes and NA cells (an epithelial cancer cell line) in vitro. S-nitroso-N-acetyl-DL-penicillamine (SNAP) and 3-morpholinosydnonimine (SIN-1) were used as NO donating reagents. The results revealed that cell viability was significantly reduced by NO derived from SNAP and SIN-1 in a dose-dependent manner. Although the role of salivary NO in normal physiology is as yet unknown, these findings suggest that excessive salivary NO plays a potential role in modifying oral mucosal diseases as a physiopathological regulator.

Quantitative assessment of apoptosis in oral lichen planus

OBJECTIVE

The aims of this study were to examine the frequency of apoptoses in oral lichen planus by in situ end labeling, to ascertain whether this technique is as sensitive as conventional histologic analysis, and to examine the effect of lymphocytic infiltration.

STUDY DESIGN

Numbers of apoptoses in hematoxylin-eosin stained sections were compared with numbers of apoptotic nuclei identified by in situ end labeling in oral lichen planus (n = 26) and normal buccal epithelium (n = 8). Immunohistochemical staining with MIB-1 and for Bcl-2 and Bax enabled possible regulatory pathways to be investigated.

RESULTS

In oral lichen planus, approximately 1 apoptotic cell was detected per millimeter of basal layer, cell death increasing with lymphocytic infiltration. Epithelial cell proliferation did not correlate with apoptosis. Bcl-2 expression was weak or absent in basal cells, and Bax was localized to upper prickle cells.

CONCLUSIONS

Increased numbers of apoptoses were detected in oral lichen planus, especially in association with lymphocytic infiltration, higher numbers being seen with hematoxylin-eosin staining than with in situ end labeling.

The management of oral lichen planus

OBJECTIVE

To review the current literature regarding the medical treatment of oral lichen planus (OLP).

DATA SOURCES

PubMed on-line Medline data searches were carried out for the years 1966-1998 to identify reports on therapy of OLP.

METHODS OF STUDY SELECTION

Single case reports or open trials were included if they covered new therapeutic approaches or suggested significant modifications of known treatment modalities. Review papers were limited to those dealing with the topic.

DATA EXTRACTION AND SYNTHESIS

Every paper was critically examined. Because of the great heterogeneity of the response criteria, many data could not be directly compared. Stronger weight was given to therapies that have proven to be effective under placebo-controlled research protocols. Attention was also drawn to potential and effective adverse effects of every drug used.

CONCLUSIONS

Among the various medications advocated for the treatment of OLP, several lack conclusive findings from adequately controlled trials. Mainly high-potency topical corticosteroids in an adhesive medium appear at present the safest and most efficacious. Adjuvant agents as antimycotics may be useful in topical steroid treatment. Systemic corticosteroids may be occasionally indicated for severe recalcitrant erosive OLP or for diffuse mucocutaneous involvement. Topical cyclosporine should be considered in steroid-unresponsive cases considering that its efficacy in OLP could be related to a systemic effect and its high cost. Classical PUVA therapy seems to have too many side effects; topical application of psoralen is promising but still experimental. Topically and systemically delivered retinoids combined with topical corticosteroids could improve the efficacy of these agents whereas complete remission is difficult to achieve with retinoids alone and they frequently cause adverse effects. Finally, there are only few data concerning the long-term effect of the medical treatments upon the course of OLP and we do not know if therapy influences the malignant evolution of OLP.

Distribution of interleukin-2, -4, -10, tumour necrosis factor-alpha and transforming growth factor-beta mRNAs in oral lichen planus

In the present study, MRNA for the cytokines interleukin-2 (IL-2), IL-4, IL-10 tumour necrosis factor-alpha (TNF-alpha) and transforming growth factor beta-1 (TGF-beta-1) were investigated in oral lichen planus (OLP) lesions using in situ hybridization with 35S-labelled oligonucleotide probes on frozen tissue sections. In addition, the expression of interferon-gamma (IFN-gamma), IL-10 and IL-4 mRNAs was analysed in cultured lesional T lymphocytes from oral lichen planus by polymerase chain reaction. Cells expressing mRNA for IL-2, IL-4, IL-10, TNF-alpha and TGF-beta 1 were found in all the biopsies studied. Approximately 1-2% of the total number of infiltrating cells in the lesions were positive for each of the different cytokine mRNAs. Most biopsies contained basement membrane-oriented, mRNA-positive cells. In the cultured T-cell lines, message for IFN-gamma was detected in all the patients, IL-10 in all but one, and IL-4 in just one of the seven patients investigated. The results suggest that mRNA for both pro- and anti-inflammatory cytokines, i.e., mixed T-helper 1 (TH1) and TH2 cytokine profiles, are generated simultaneously by a limited number of cells in chronic lesions of OLP.

Oral lichen planus: an immunohistochemical study of heat shock proteins (HSPs) and cytokeratins (CKs) and a unifying hypothesis of pathogenesis

The expression of heat shock proteins HSP60 and HSP70 and cytokeratins CK1/10 and CK7/18 were compared in epithelium of oral lichen planus (OLP) lesions and oral fibromas using an avidin-biotin-peroxidase complex (ABC) immunohistochemical method. An immunostaining intensity distribution (IID) index was developed to assess staining intensity and the proportion of positively stained cells in different layers of the epithelium. The expression of HSP60 in the basal layer was significantly higher in OLP than in fibromas. No difference in HSP70 expression was evident between OLP and fibromas. The expression of CK1/10 in the epithelial basal and suprabasal layers was significantly higher in OLP than in fibromas. There was no demonstrable staining for CK7/18 in either OLP or fibromas. A significant correlation was evident between the expression of HSP60 and CK1/10 in the basal epithelial cells in OLP. The findings support a role for HSP60 in the pathogenesis of OLP. A unifying hypothesis of the pathogenesis of OLP, involving two sequential immune reactions, is proposed.

Immunocompetent cells in amalgam-associated oral lichenoid contact lesions

Inflammatory cells in amalgam-associated, oral lichenoid contact lesions (OLL) were studied in 19 patients by immunocytochemistry using monoclonal antibodies. Ten of the patients displayed allergic patch test (PT) reactions to several mercury compounds and nine were negative. The immunocytochemical quantification showed a uniform composition of the inflammatory mononuclear cells in the two study groups. The number of HLA-D/DR-positive dendritic cells (P<0.001) and CD1a-positive Langerhans cells (P=0.035) was significantly lower in the PT-negative than PT-positive patients. HLA-D/DR expression on keratinocytes varied from negative to full thickness staining of the epithelium. HLA-D/DR expression in the full thickness of epithelium (3) or through the basal and spinous cell layers (2) was seen in 5 of 8 PT-positive patients, whereas none of the PT-negative patients had this staining pattern (P=0.045). These patients also showed a good clinical response after amalgam removal. Consequently, OLL may represent a true delayed hypersensitivity reaction with a trans-epithelial route of entrance of the metal haptens released from dental restorative materials.

Topical corticosteroids in association with miconazole and chlorhexidine in the long-term management of atrophic-erosive oral lichen planus: a placebo-controlled and comparative study between clobetasol and fluocinonide

OBJECTIVE

To evaluate the efficacy of a combination of topical corticosteroids with topical antimycotic drugs in the therapy of atrophic-erosive forms of oral lichen planus (OLP).

PATIENTS AND METHODS

The study population consisted of 60 patients with OLP subdivided into three groups matched for sex and age. The first group (25 patients) and the second group (24 patients) received respectively 0.05% clobetasol propionate ointment or 0.05% fluocinonide ointment in an adhesive medium (4% hydroxyethyl cellulose gel) plus in each case antimycotic treatment consisting of miconazole gel and 0.12% chlorhexidine mouthwashes. The third group (11 patients), placebo group, received only hydroxyethyl cellulose gel and antimycotic treatment as above. All the treatment regimens were carried out for 6 months. Each patient was examined every 2 months during the 6-month period of active treatment and for a further 6 months of follow-up. Objective and subjective clinical progress was scored and compared between the three groups. Plasma cortisol levels were monitored in half the patients using the topical corticosteroids.

RESULTS

All patients treated with clobetasol and 90% of the patients treated with fluocinonide witnessed some improvement, whereas in the placebo group only 20% of patients improved (P < 0.0001 and P = 0.00029, respectively. However, when considering complete responses, only clobetasol gave significantly better results than placebo. Clobetasol resolved 75% of the lesions whereas fluocinonide was effective in 25% of cases and placebo in none. Clobetasol achieved better results statistically than did fluocinonide (P = 0.00442) and placebo (P = 0.00049) whereas there was no statistical difference among fluocinonide and placebo (P = 0.140). Similar results were obtained for symptoms. Both drugs were shown to be effective in the treatment of erosive lesions, but clobetasol was considerably more efficacious than fluocinonide in the atrophic areas (75% vs 25% of total response, respectively) (P = 0.00442). None of the treated patients contracted oropharyngeal candidiasis. After 6 months of follow-up, 65% of the clobetasol-treated group and 55% of the fluocinonide group were stable. Estimation of plasma cortisol levels showed no significant systemic adverse effects of clobetasol or fluocinonide.

CONCLUSIONS

Our results suggest that a very potent topical corticosteroid such as clobetasol may control OLP in most cases, with no significant adrenal suppression or adverse effects. Moreover, a concomitant antimycotic treatment with miconazole gel and chlorhexidine mouthwashes is a useful and safe prophylaxis against oropharyngeal candidiasis.

Immunohistochemistry of 'tertiary lymphoid follicles' in oral amalgam-associated lichenoid lesions

OBJECTIVES

To characterise lymphoid follicle-like aggregates incidentally found to occur in biopsies of oral lichenoid reactions (OLR) and to correlate the findings to hyperplastic tonsil follicles.

DESIGN

An immunocytochemical analysis of archival material.

SUBJECTS AND METHODS

In an arbitrarily selected period 1992-1994 with a total of 13,924 oral biopsies, 2407 cases were signed out as OLR or lichen planus. These were microscopically reviewed, with the purpose to retrieve all cases showing histologic changes resembling secondary lymphoid follicles.

RESULTS

87 cases showed lymphoid follicle-like changes and 82 of these were in oral regions known to constitutively lack 'organised MALT'. Unexpectedly, all of the 82 were found retrospectively to be in close or direct contact with amalgam fillings. Immunocytochemically, using antibodies to B and T cells, macrophages, follicular dendritic cells and proliferation and apoptosis markers, the mucosal follicles stained similar to tonsillar secondary follicles. In several of an additional 11 OLR cases with histologic changes suggestive of primary follicles, we also found immunocytochemical evidence of such changes.

CONCLUSIONS

'Tertiary lymphoid follicles' may occasionally develop in OLR at sites of the oral mucosa constitutively lacking organised lymphoid tissue. The microenvironment of the OLR T cell infiltrate may occasionally favour such follicle development and amalgam constituents may causally be involved in an unknown way.

Analysis of desquamative gingivitis using direct immunofluorescence in conjunction with histology

Chronic desquamative gingivitis (DG) is a common condition often first recognized by periodontists. DG is characterized clinically by erythema with epithelial desquamation, ulceration, and/or the presence of vesiculobullous lesions of the free and attached gingiva. However, DG is actually a clinical manifestation of several different disease processes, particularly lichen planus and benign mucous membrane pemphigoid. Correct diagnosis in DG is critical since proper treatment and follow-up will depend on which disease is involved. However, the diseases that cause DG frequently present diagnostic problems because their lesions often resemble each other clinically and routine histological examination sometimes cannot differentiate between them. Thus, immunohistology, particularly immunofluorescence, is increasingly being used with routine histology to more accurately diagnose DG diseases. This article reviews our experience over the past 10 years in the diagnosis of 72 cases of DG using direct immunofluorescent (DIF) in conjunction with histology and clinical evaluation. Of the 72 DG cases in this study, 30 cases were diagnosed as erosive lichen planus or lichenoid mucositis; 29 cases were diagnosed as benign mucous membrane pemphigoid; 2 cases each of linear IgA disease and pemphigus vulgaris were diagnosed; there was 1 case of bullous pemphigoid; and 1 suspected case of paraneoplastic pemphigus. Even with DIF analysis, 7 cases could not be definitively assigned a particular cause. DIF analysis is not only proving very useful for differential diagnosis, but also adds insight into possible pathogenic mechanisms of DG.

Oral keratinocytes derived from the peritonsillar mucosa express the proinflammatory cytokine IL-6 without prior stimulation

The aim of the present study is to examine the cytokine expression and corresponding receptor pattern of human oral mucosa-derived keratinocytes. The mRNA expression of these cytokines from isolated and purified cells was measured by a RT-PCR method, the protein production by ELISA, and the receptor expression was determined by FACS analysis. In freshly isolated oral keratinocytes, IL-1alpha, IL-1alpha receptor antagonist, IL-6, IL-8, TGF-beta, TNF-alpha, and bFGF were detectable at the protein and mRNA level, whereas PDGF and TGF-alpha were found only at the mRNA level. There were no detectable signals for IL-2 and IL-4. The cytokine production at the protein level was independent from stimulation with PMA (phorbol myristate acetate). Unstimulated commercially available and primary isolated epidermal keratinocytes showed similar cytokine pattern except a lack of IL-6. FACS analysis revealed receptor expression on oral keratinocytes for IL-1, IL-2, IL-4, IL-6, EGF, IFN-gamma, and PDGF. In addition, receptor mRNA for IL-8, TNF-alpha, FGF-2 and KGF could be detected, but not for IL-10. Our results show that human oral keratinocytes produce a cytokine panel comparable to epidermal keratinocytes. In contrast to the epidermis, IL-6 was produced by human oral keratinocytes constitutively without prior stimulation, which may indicate their active regulation role in the maintenance of the oral mucosa.

Associations between mast cells and laminin in oral lichen planus

Mast cell numbers are increased significantly in oral lichen planus (OLP). In other inflammatory conditions, mast cells frequently adhere to extracellular matrix proteins such as laminin. The aim of this study, therefore, was to determine whether the distribution of mast cells in OLP is related topographically to laminin in vascular and epithelial basement membranes. Monoclonal antibodies for tryptase, laminin and the alpha6beta1 CD49f laminin-binding integrin were used to identify mast cells, basement membranes (blood vessels and basal epithelium) and the "classical" laminin adhesion receptor, respectively. A double-labelling immunoperoxidase technique was employed to examine and compare mast cell-laminin relationships in OLP (n=19) and normal buccal mucosa (NBM, n=13). In both OLP and NBM, the majority of mast cells were located close to vascular basement membranes. Quantitative studies revealed that the number of mast cells associated with the laminin of vascular basement membranes (distance <1 microm) was two-fold and three-fold higher, respectively, in the superficial and deep layers in OLP compared with NBM (P<0.001). The frequency distribution of mast cells associated with basal epithelium was not statistically different in both groups (P>0.05). The association of mast cells with laminin may be an important determinant of mast cell density in OLP During OLP lesion formation and progression, the preferential distribution of mast cells in the immediate perivascular region provides an ideal situation for mast cell-derived mediators to influence the vascular endothelium.

Update on oral lichen planus: etiopathogenesis and management

Lichen planus (LP) is a relatively common disorder of the stratified squamous epithelia, which is, in many ways, an enigma. This paper is the consensus outcome of a workshop held in Switzerland in 1995, involving a selection of clinicians and scientists with an interest in the condition and its management. The oral (OLP) eruptions usually have a distinct clinical morphology and characteristic distribution, but OLP may also present a confusing array of patterns and forms, and other disorders may clinically simulate OLP. Lesions may affect other mucosae and/or skin. Lichen planus is probably of multifactorial origin, sometimes induced by drugs or dental materials, often idiopathic, and with an immunopathogenesis involving T-cells in particular. The etiopathogenesis appears to be complex, with interactions between and among genetic, environmental, and lifestyle factors, but much has now been clarified about the mechanisms involved, and interesting new associations, such as with liver disease, have emerged. The management of lichen planus is still not totally satisfactory, and there is as yet no definitive treatment, but there have been advances in the control of the condition. There is no curative treatment available; immunomodulation, however, can control the condition. Based on the observed increased risk of malignant development, OLP patients should be offered regular follow-up examination from two to four times annually and asked to report any changes in their lesions and/or symptoms. Follow-up may be particularly important in patients with atrophic/ulcerative/erosive affections of the tongue, the gingiva, or the buccal mucosa. Much more research is required into the genetic and environmental aspects of lichen planus, into the premalignant potential, and into the possible associations with chronic liver, and other disorders. More clinical studies are required into the possible efficacy of immunomodulatory drugs such as pentoxifylline and thalidomide.

Intra-epithelial subpopulations of T lymphocytes and Langerhans cells in oral lichen planus

This study has addressed the question of whether there is selective recruitment and distribution of intra-epithelial leucocytes in lesions of oral lichen planus (OLP). T-lymphocyte subsets were examined in the epithelium and peripheral blood of patients and controls using flow cytometry and double immunofluorescence, and the relationship between keratinocyte intercellular adhesion molecule-1 (ICAM-1) expression with T-lymphocyte and Langerhans cell (LC) distribution was examined. The circulating 'memory' subset (CD45RO+) of T-helper cells (CD4+) was increased from 49.1% in controls to 65.7% in patients (P=0.005), while the 'naive' subset (CD45RA+), which was absent from control epithelium, comprised 24% of helper cells in OLP (P=0.016). Fewer LC expressed CD45RO in OLP than in controls (P=0.037) and all T-cell and LC counts were significantly raised in ICAM-1-expressing areas of epithelium. These data demonstrate changes in intra-epithelial T-lymphocyte and LC populations compared with normal oral mucosa and suggest there is selective recruitment in OLP. In addition, keratinocyte ICAM-1 expression does appear to be associated with accumulation of infiltrating T lymphocytes and LC.

Immunopathogenesis of oral lichen planus and recurrent aphthous stomatitis

Oral mucosal bullous/desquamative/ulcerative diseases involve immunopathological mechanisms that account for loss of adhesion between contiguous keratinocytes or to structures within the basal lamina. Some are antibody mediated, in which specific adhesion molecules of the desmosome, hemidesmosome, and basement membrane become antigenic targets. Oral lichen planus and recurrent apthous ulcers, although manifesting disparate clinical appearances and natural history, share immunopathological features that involve T cell-mediated immunity. Although the antigens, haptens, or autoantigens are not usually apparent, current research poses the hypothesis that both of these common oral mucosal diseases are a delayed-type hypersensitivity or cell-mediated response to an antigenic stimulus residing within the epithelium. This article reviews the research evidence for this hypothesis.

Immunohistochemical localization of mast cells and mast cell-nerve interactions in oral lichen planus

OBJECTIVES

Mast cell mediators are likely to be involved in at least some aspects of the immunopathogenesis of oral lichen planus (OLP). The aim of this project was to map mast cell populations in OLP and identify possible sites of mast cell-nerve interactions.

MATERIALS AND METHODS

Monoclonal antibodies specific for tryptase and neurofilaments were used to identify mast cells and nerves respectively in an immunohistochemical study of OLP (n = 25) and normal oral buccal mucosa (NOBM) (n = 13) using a double-labelling protocol. Data analysis used paired t-test, multiway analysis of variance and Wilcoxon rank tests.

RESULTS

Morphometric analyses showed the greatest mast cell density in the most superficial of the three depth layers examined in OLP, an increase of 130% compared with NOBM. Mast cells associated with neurofilaments ranged from 21.9% in OLP to 10.2% in NOBM. Mean epithelial thickness was significantly lower in OLP (P < 0.001) but without a strong correlation with mast cell density.

CONCLUSIONS

Increased mast cell and mast cell-nerve interactions in OLP suggest both a controlling role over the lesional cell populations and a secondary role to the immune response once this becomes established.

An atypical verrucous carcinoma of the tongue arising in a patient with oral lichen planus associated with hepatitis C virus infection

Recently, a clinical relationship between oral lichen planus (OLP) and hepatitis C virus (HCV) infection has been suggested, but the role of this virus on the course of OLP is unknown. We report an unusual lingual localisation of verrucous carcinoma arising in a patient with histologically confirmed OLP and HCV infection diagnosed with second generation enzyme-linked immunosorbent assay and recombinant immunoblot assay. Serum HCV-RNA detected using nested reverse transcriptase polymerase chain reaction (RT-PCR) confirm HCV replication. No classical risk factors associated with verrucous carcinoma were present.

Oral, perioral and systemic pathosis in HgCl2-induced autoimmunity in the BN rat

Male BN rats were repeatedly skin-injected with HgCl2 solution and sacrificed after 6, 9, 14, 21, 28 or 24 days. Mononuclear cell infiltrates were observed in the oral mucosa and in lacrimal, salivary and thyroid glands from 6-9 days onwards, with a peak at 14-21 days. Immunohistochemistry identified these cells as predominantly T cells with some NK cells but very few B cells. Reversible parenchymal changes were observed but there was no obvious persistent tissue destruction. Serum titers of IgE, IgG1, anti-laminin and anti-DNP, but not IgG2a antibodies, were raised and peaked at 14-21 days. However, there was no correlation, within animals, between these titers and the extent of mononuclear cell infiltration. Mercury was histochemically detected within dendritic cells/macrophages in the connective tissue stroma of the glands and in the oral mucosa, but no correlation was found between the distribution of mercury and the degree of inflammation. We conclude that the accumulation of mononuclear cells in oral and perioral tissues of HgCl2-treated BN rats does not represent a local immune response to tissue-retained Hg. Instead, we propose that the extravasation represents an epiphenomenon that is not necessarily deleterious to the infiltrated organ.

Immunologic aspects of dermal and oral lichen planus: a review

There have been many investigations, both experimental and epidemiologic, of the forms of LP affecting the skin and oral mucosae. These studies have provided a varied range of hypotheses to explain not only the factors determining susceptibility to and onset of this disease, but also the immunologic mechanisms leading to the pathosis with which LP is associated. Much progress has been made, especially through in vitro studies, regarding detailed aspects of the immunology of LP. However, data is often conflicting or incomplete. In this review we attempt to bring together the currently available data regarding the immunologic basis of LP.

T-cell receptor V beta usage by lesional lymphocytes in oral lichen planus

To determine whether the T-cell inflammatory infiltrate in oral lichen planus (OLP) represents a selective activation and expansion of a limited repertoire of T-cell receptor (TCR) specific T-cells, V beta gene expression was investigated in lesional T-lymphocytes in OLP. A reverse transcriptase-polymerase chain reaction (RT-PCR) technique was used to amplify the 24 major V beta gene sub-families of infiltrating mucosal lymphocytes and peripheral blood mononuclear cells (PMNC) in seven patients with reticular OLP and four healthy control patients. Specificity of amplified products was confirmed by Southern blotting with a C beta internal probe. TCR V beta usage by lesional T-cells in OLP was markedly heterogeneous 5-23 V beta sub-families). In 6/8 patients with OLP, V beta usage was restricted with < or = 20/25 sub-families detected; only one of the V beta sub-families (V beta 8) was present in all of the OLP patients demonstrating TCR V beta restriction. In contrast, TCR V beta usage was unrestricted in PMNC from OLP patients and controls (> or = 23/ 25 sub-families detected). In three patients, certain V beta sub-families (V beta 13, V beta 14 & V beta 15) were present in the lesional T-cell population but were under-represented in PMNC. These results suggest a selective V beta gene usage by lesional infiltrating T-cells in oral lichen planus. The non-uniformity of V beta restriction in lesional T-cells does not support the concept of a common superantigen in OLP and reflects the heterogeneity of the disease.

TCR V beta gene expression in lesional T lymphocyte cell lines in oral lichen planus

To study V beta gene expression in oral lichen planus (OLP) lesional T lymphocytes cell lines.

MATERIALS AND METHODS

Lesional T lymphocytes were isolated from eight OLP patients and cell lines established. The total RNA was extracted from these lymphocyte cell lines and reverse transcribed. cDNA was amplified by the polymerase chain reaction (PCR) using a panel of 26 V beta-specific oligonucleotide primers followed by qualitative analysis of the electrophoresed reaction products.

RESULTS

V beta 1, 2, 3, 5.1, 6.1-3, 7, 8, 9, 22, 23, and 24 were represented consistently in all of the OLP samples, V beta 11, 12, and 17 were consistently negative, while the other V beta families (V beta 4, 5.2-3, 10, 13.1, 13.2, 14, 15, 16, 18, 19, 20, and 21) were variable. V beta 22 and 23 were the most strongly expressed in all patients.

CONCLUSIONS

A limited T cell receptor (TCR) gene usage indicates a degree of oligoclonality within these lesional T lymphocyte cell lines from OLP. This implies that OLP may be an antigen-specific disease or linked to a limited number of superantigens.

Clinical characteristics and treatment of patients with oral lichen planus in Israel

Oral lichen planus (OLP) has a multiple-site involvement, with the buccal mucosa being the most prevalent. A possible relationship between OLP and the risk of malignancies in the involved site is documented. The characteristics of OLP have been studied in different populations; however, no similar studies have been conducted in any Jewish population. The purpose of this study was to evaluate the natural history of OLP in Israeli Jewish patients. Data were collected from 157 charts of patients with histologically confirmed OLP. No evidence suggesting a connection between OLP and diabetes, cardiovascular disease, smoking, alcohol use, or positive Candida culture was found. Skin involvement of lichen planus was found in one fifth of the patients. Symptomatic OLP was noted in half of the patients, mainly in those with the erosive form. In 65% of the patients with symptoms, improvement by more than 50% was shown within 2 weeks of steroid use. The transformation rate of 1.3% of OLP into malignancy was observed in the entire group. A constant follow-up for contributing symptoms and for early diagnosis of suspected transformed lesions is of utmost importance.

Hepatitis C virus infection in Italian patients with oral lichen planus: a prospective case-control study

To assess the aetiology of liver disease associated with lichen planus, we prospectively studied 70 consecutive newly diagnosed patients with oral lichen planus (OLP) living in northwest Italy (Piemonte) and 70 controls matched for age and sex with other oral keratoses coming from the same district. Twenty-two patients with OLP (31.4%) and 9 controls (12.9%) were found to be affected by chronic liver disease (CLD) (P = 0.014). In sixteen of the 22 OLP patients with CLD the liver disease was hepatitis C virus (HCV)-related, whereas 2 of the 9 controls had a HCV-related CLD (P = 0.016). In another OLP case, liver damage was related to a combination of HCV and alcohol abuse. The prevalence of HCV antibodies in the whole OLP group (27.1%) was significantly higher than in controls (4.3%) (P = 0.014), whereas no difference was found between the OLP and control groups regarding hepatitis B virus markers and other common causes of CLD. HCV infection was more frequently found in patients with erosive OLP (58.8%) than in patients with non-erosive OLP (13.2%) (P = 0.004). Serum HCV-RNA was detected by polymerase chain reaction (RT-PCR) in the majority (93.7%) of OLP patients who had HCV antibodies. Excluding OLP and control patients with HCV markers, there was no difference between the two groups regarding frequency of CLD. Our data show that HCV is probably the main pathogenic factor in liver disease of Italian patients with OLP, and suggests that HCV could be involved in the pathogenesis of OLP.

T cell antigen receptor expression by intra-epithelial lymphocytes in oral lichen planus

The distribution of T lymphocytes expressing the alpha beta or gamma delta heterodimer of the T cell receptor (TCR) was examined in normal oral mucosa (NOM) and reticular oral lichen planus (OLP) using a panel of antibodies specific for CD3, the alpha beta TCR and the gamma delta TCR. Intra-epithelial lymphocytes were counted and epithelial surface length was measured by image analysis. T cells in the lamina propria were not quantified. Total intra-epithelial lymphocytes were increased in OLP compared with NOM (P = 0.0004). The proportions of cells expressing the gamma delta TCR in NOM and OLP were 10% and 9.3%, respectively, suggesting there is no selective recruitment from the circulation of either alpha beta or gamma delta TCR-bearing cells into normal oral epithelium or that affected by OLP. The role, if any, of gamma delta T cells in the pathogenesis of OLP remains to be determined.

Altered interface adhesion molecules in oral lichen planus

OBJECTIVE

To evaluate expression of key epithelial-connective tissue interface adhesion molecules (basal keratinocyte integrins and extracellular matrix receptors) in oral lichen planus (LP).

DESIGN

Integrins alpha 3, alpha 6, beta 1, beta 4 and basement membrane proteins laminin 1, laminin 5, collagen IV, and collagen VII were immunohistochemically identified in frozen biopsy specimens (14 oral LP and II matched controls) using a standard avidin-biotin-peroxidase technique.

RESULTS

An increased staining intensity of all antigens in LP was shown, as compared to controls. Integrin expression by LP keratinocytes was generally more intense and appeared on more upper level cells. Staining for basement membrane-associated extracellular matrix proteins was also generally more intense, although fragmentation and gaps were typically seen. Reactions for alpha 6, beta 4, laminin 5, and collagen VII stains were particularly intense along the basement membrane. In LP, strands of laminin 5, collagen IV, and collagen VII appeared in the submucosa approximating or duplicating the basement membrane.

CONCLUSIONS

The apparent increased expression of the interface-associated adhesion molecules may be reflective of a keratinocyte compensatory response (due to lymphocyte-mediated damage) that would functionally help resist epithelial separation (ulceration). Expression of alpha 3 beta 1 and alpha 6 beta 4 would also assist in epithelial migration associated with wound repair. We interpret the submucosal extensions and deposits of basement membrane proteins as representing remnants of basement membrane, indicating recent remodeling or atrophy of epithelial rete ridges.

Expression of the E-selectin gene in human gingival epithelial tissue

E-selectin is an adhesion molecule, expressed by cytokine-activated endothelial cells, that participates in the binding of neutrophils. Recent studies in our laboratory documented binding of the E-selectin-specific monoclonal antibody H4/18 to keratinocytes in inflamed human oral mucosa, particularly gingival epithelium. To determine whether this immunoreactivity was due to expression of authentic E-selectin, the presence of E-selectin mRNA in gingival epithelium was analysed using the polymerase chain reaction (PCR). Reverse transcription of epithelial RNA and amplification of cDNA with E-selectin-specific primers resulted in the formation of a 178 nucleotide PCR product identical to that obtained from cytokine-activated endothelial cells. Sequencing of the PCR product revealed 100% homology between epithelial and endothelial E-selectin fragments. Epithelial preparations did not contain mRNA for von Willebrand factor, excluding the possibility of contamination by endothelial cells. These results confirm immunohistochemical studies of E-selectin immunoreactivity in human oral mucosa and demonstrate that E-selectin expression is not confined to endothelium.

Abnormal EBV immune status in oral lichen planus

OBJECTIVE

To investigate any possible association between oral lichen planus (OLP) and the humoral immune response to Epstein-Barr virus (EBV).

MATERIAL AND METHODS

The population consisted of 22 patients with histologically verified OLP and 22 healthy sex- and age-matched controls without any oral mucosal diseases. Specific serum IgG antibodies (Ab) towards EBV early antigen (EA) and nuclear antigen-I (EBNA) and IgM Ab towards EBV EA were determined by ELISA.

RESULTS

The optometric density (OD) IgG anti-EA Ab levels were significantly higher in OLP patients than in controls and a significantly negative correlation between duration of symptoms from OLP and IgG anti-EA OD Ab values was demonstrated. IgM anti-EA and IgG anti-EBNA OD Ab levels were not significantly different between the two groups.

CONCLUSION

The hypothesis of any possible association between EBV and OLP has never been tested but the present results seem to lend support for an aberration in the humoral response to EBV in OLP patients.

Expression of c-erbB-2 protein in keratinocytes of oral mucosal lichen planus and subsequent squamous cell carcinoma

Oral mucosal lichen planus (OMLP) is a well recognized mucosal disease with unknown etiology. Considerable controversy exists as to whether OMLP is intrinsically premalignant, or if the disorder facilitates the development of oral mucosal squamous cell carcinoma (OMSCC) by external factors. The aim of the present study was to investigate the expression of c-erbB-2 protein in the keratinocytes of initial biopsies or oral mucosal disorders diagnosed as OMLP with no evidence of epithelial dysplasia, and to compare the results with the expression of c-erbB-2 protein in subsequent biopsies obtained from the same patients. These results were compared with the findings from control groups (patients with dysplasia with no evidence of OMLP, patients with OMSCC with no evidence of OMLP and normal oral mucosa). The expression of the c-erbB-2 protein was evaluated by immunohistochemical staining of the gene product with the avidin-biotin-complex method using paraffin-embedded tissues sections. Five of the initial biopsies from patients with OMLP expressed the c-erbB-2 protein and one did not. None of the OMLP cases that subsequently showed evidence of dysplasia expressed the c-erbB-2 protein, and of the three OMSCC specimens from the patients with OMLP, two were negative and one expressed c-erbB-2 protein. The specimens from the control groups all expressed the c-erbB-2 protein. The results indicated the probability of the absence of c-erbB-2 staining being an indication of a potential for neoplastic transformation in OMLP with dysplastic changes.

Is there a role for tumor necrosis factor-alpha (TNF-alpha) in oral lichen planus?

Oral lichen planus (OLP) is a T cell-mediated inflammatory disease of the oral mucosa. T lymphocytes accumulate within OLP lesions by extravasation from the local microvasculature and subsequent migration to the oral epithelium. Tumor necrosis factor-alpha (TNF-alpha) is a cytokine involved primarily in T cell-mediated immunopathological reactions, and it is implicated in diseases which bear clinical and histological similarities to OLP. This review examines the role of TNF-alpha in the initiation and progression of OLP, and summarises evidence for a key role for TNF-alpha in this disease. A unifying hypothesis for the involvement of TNF-alpha in the immunopathogenesis of OLP is presented. Based on this model, a variety of current therapies are explained and several alternative approaches suggested.

Mucosal cell-mediated immunological changes associated with experimental graft-versus-host disease

This study examined the histological changes and local cellular immune response induced within the lingual mucosa in an allogeneic F1 hybrid rat model of graft-versus-host disease (GvHD) with a view to studying oral lymphocyte-epithelial cell reactions. Highest levels of disease, as reflected by both a GvHD index and the extent of the oral mucosal changes, were obtained using primed donor (Lewis rats) splenocytes and irradiated hosts (Lew/Da rats). The lingual mucosae of test animals were characterised by irregular epithelial keratosis, an absence of basal cell liquefaction and a diffuse inflammatory cell infiltrate, histological features consistent with an oral lichenoid tissue reaction. Immunohistochemical studies showed that mucosal involvement was characterised by infiltration of the lamina propria by NK cells (CD8+, CD5-), "activated" cells (CD25+) and T cells (CD5+) with selective migration of the latter, including a CD5+, CD8- subset (helper/inducer T cell), into the epithelium. Epithelial expression of Ia was invariably associated with these inflammatory cell infiltrates and correlated with the GvHD index. These findings suggest the presence of local mucosal T cell activation in the absence of detectable epithelial cell damage, which may be equivalent to the early initiating events in the pathogenesis of oral lichen planus. However, whilst experimental graft-versus-host disease appears to be a useful model for studying lymphocyte-epithelial interactions, the induced oral mucosal changes are more consistent with a lichenoid reaction rather than lichen planus.

Studies of the inflammatory process and malignant potential of oral mucosal lichen planus

Oral mucosal lichen planus (OMLP) is a well recognized mucosal disease with unknown aetiology. Considerable controversy exists as to whether OMLP is intrinsically premalignant, or if the disorder facilitates the development of oral mucosal squamous cell carcinoma (OMSCC) by external factors. The aim of the present studies was to investigate the expression of c-erbB-2 protein in the keratinocytes of the initial biopsies of oral mucosal disorders diagnosed as OMLP with no evidence of epithelial dysplasia and to compare the results with the expression of c-erbB-2 protein in subsequent biopsies obtained from the same patients. These results were compared with the findings from another 26 biopsies from patients with OMLP and control groups (patients with dysplasia with no evidence of OMLP, patients with OMSCC with no evidence of OMLP and normal oral mucosa). The expression of the c-erbB-2 protein was evaluated by immunohistochemical staining of the gene product with the avidin-biotin-complex method using both fresh frozen and paraffin-embedded tissue sections. Five of the initial biopsies from patients with OMLP expressed the c-erbB-2 protein and one did not. None of the OMLP cases that subsequently showed evidence of dysplasia expressed the c-erbB-2 protein and of the OMSCC specimens from the patients with OMLP, 2 were negative and 1 expressed c-erbB-2 protein. Within the other group of OMLP specimens 3 (3/26) were negative for c-erbB-2 staining. The specimens from the control groups all expressed the c-erbB-2 protein. The results indicated the probability of the absence of c-erbB-2 staining being an indication of a potential for neoplastic transformation in OMLP with dysplastic changes.