Expression of the CD54 (ICAM-1) and CD11a (LFA-1) adhesion molecules in oral mucosal inflammation

An exotic pathogenetic mechanism of angiogenesis in oral lichen planus-A systematic review

OBJECTIVE

Angiogenesis plays a vital role at the molecular level in various inflammatory lesions, that lead to their chronicity. Oral lichen planus is an immune-mediated chronic inflammatory disorder. The angiogenetic role and exact mechanisms in oral lichen planus are still unclear due to a dearth of studies. Its clinical significance with angiogenesis also requires further elucidation necessitating a thorough review of the studies that have been conducted so far. The present review was designed to identify the dependence of oral lichen planus progression on angiogenesis which could aid in devising metronomic treatments required to halt the progression of this disease.

MATERIALS AND METHODS

A thorough search was made using MEDLINE by PubMed, Scopus, Google scholar, Cochrane library, and EMBASE databases. Original research articles, that immunohistochemically evaluated angiogenesis in oral lichen planus were included for review. Risk of bias was analysed for each study using Modified Newcastle-Ottawa scale and Review Manager 5.4 was used to output its result.

RESULTS

Twenty-nine published articles were included for data synthesis. The most commonly employed antibody was CD34, however, upregulated VEGF expression was the principal while ICAM-1, VCAM-1, and PECAM-1 were critical angiogenic factors to mediate angiogenesis in oral lichen planus.

CONCLUSION

The current evidence supports that angiogenesis, a fundamental pathogenetic mechanism of oral lichen planus, leads to its persistence and chronicity. However, studies with a larger sample size, standard evaluation criteria, different subtypes, and adequate follow-up are warranted.

Release of HIV-1 sequestered in the vesicles of oral and genital mucosal epithelial cells by epithelial-lymphocyte interaction

Oropharyngeal mucosal epithelia of fetuses/neonates/infants and the genital epithelia of adults play a critical role in HIV-1 mother-to-child transmission and sexual transmission of virus, respectively. To study the mechanisms of HIV-1 transmission through mucosal epithelium, we established polarized tonsil, cervical and foreskin epithelial cells. Analysis of HIV-1 transmission through epithelial cells showed that approximately 0.05% of initially inoculated virions transmigrated via epithelium. More than 90% of internalized virions were sequestered in the endosomes of epithelial cells, including multivesicular bodies (MVBs) and vacuoles. Intraepithelial HIV-1 remained infectious for 9 days without viral release. Release of sequestered intraepithelial HIV-1 was induced by the calcium ionophore ionomycin and by cytochalasin D, which increase intracellular calcium and disrupt the cortical actin of epithelial cells, respectively. Cocultivation of epithelial cells containing HIV-1 with activated peripheral blood mononuclear cells and CD4+ T lymphocytes led to the disruption of epithelial cortical actin and spread of virus from epithelial cells to lymphocytes. Treatment of epithelial cells with proinflammatory cytokines tumor necrosis factor-alpha and interferon gamma also induced reorganization of cortical actin and release of virus. Inhibition of MVB formation by small interfering RNA (siRNA)-mediated silencing of its critical protein hepatocyte growth factor-regulated tyrosine kinase substrate (Hrs) expression reduced viral sequestration in epithelial cells and its transmission from epithelial cells to lymphocytes by ~60-70%. Furthermore, inhibition of vacuole formation of epithelial cells by siRNA-inactivated rabankyrin-5 expression also significantly reduced HIV-1 sequestration in epithelial cells and spread of virus from epithelial cells to lymphocytes. Interaction of the intercellular adhesion molecule-1 of epithelial cells with the function-associated antigen-1 of lymphocytes was important for inducing the release of sequestered HIV-1 from epithelial cells and facilitating cell-to-cell spread of virus from epithelial cells to lymphocytes. This mechanism may serve as a pathway of HIV-1 mucosal transmission.

HBO: a possible supplementary therapy for oral potentially malignant disorders

Oral potentially malignant disorders (OPMDs) are chronic inflammatory diseases in which cells suffer hypoxia referring to deprivation of adequate oxygen supply. Hyperbaric oxygen treatment (HBO), which can increase oxygen tension and delivery to oxygen-deficient tissue, is a supplementary therapy to improve or cure disorders involving hypoxia. Although the applications of HBO in wound healings, acute ischemic stroke, radiation-induced soft tissue injury and cancers are extensively reported, there are only few studies on their effect in OPMDs. Not only does HBO furnish oxygen-it also possesses potent anti-inflammatory properties. At the cellular level, HBO can decrease lymphocyte proliferation and promote apoptosis of fibroblasts. At the molecular level, it can decrease expression of HIF, ICAM-1, TNF-α, TGF-β, and IFN-γ, as well as increase vascular VEGF expression and angiogenesis. Thus, we hypothesize that HBO may contribute to treat OPMDs, including oral lichen planus, oral leukoplakia, and oral submucous fibrosis both at the cellular level and the molecular level, and that it would be a safe and inexpensive therapeutic strategy.

Mucosal disease series. Number VI. Recurrent aphthous stomatitis

Recurrent aphthous stomatitis (RAS; aphthae; canker sores) is a common condition which is characterized by multiple recurrent small, round or ovoid ulcers with circumscribed margins, erythematous haloes, and yellow or grey floors typically presenting first in childhood or adolescence. RAS occurs worldwide although it appears most common in the developed world. The aetiology of RAS is not entirely clear. Despite many studies trying to identify a causal microorganism, RAS does not appear to be infectious. A genetic predisposition is present, as shown by strong associations with genotypes of IL-1beta; IL-6 in RAS patients, and a positive family history in about one-third of patients with RAS. Haematinic deficiency is found in up to 20% of patients. Cessation of smoking may precipitate or exacerbate RAS in some cases. Ulcers similar to RAS may be seen in human immunodeficiency virus disease and some other immune defects, and drugs, especially non-steroidal anti-inflammatory drugs and nicorandil may produce lesions clinically similar to RAS. Topical corticosteroids can often control RAS. However, the treatment of RAS remains unsatisfactory, as most therapies only reduce the severity of the ulceration and do not stop recurrence.

Recurrent aphthous ulcers today: a review of the growing knowledge

Recurrent aphthous ulcers represent a very common but poorly understood mucosal disorder. They occur in men and women of all ages, races and geographic regions. It is estimated that at least 1 in 5 individuals has at least once been afflicted with aphthous ulcers. The condition is classified as minor, major, and herpetiform on the basis of ulcer size and number. Attacks may be precipitated by local trauma, stress, food intake, drugs, hormonal changes and vitamin and trace element deficiencies. Local and systemic conditions, and genetic, immunological and microbial factors all may play a role in the pathogenesis of recurrent aphthous ulceration (RAU). However, to date, no principal cause has been discovered. Since the aetiology is unknown, diagnosis is entirely based on history and clinical criteria and no laboratory procedures exist to confirm the diagnosis. Although RAU may be a marker of an underlying systemic illness such as coeliac disease, or may present as one of the features of Behcet's disease, in most cases no additional body systems are affected, and patients remain otherwise fit and well. Different aetiologies and mechanisms might be operative in the aetiopathogenesis of aphthous ulceration, but pain, recurrence, self-limitation of the condition, and destruction of the epithelium seem to be the ultimate outcomes. There is no curative therapy to prevent the recurrence of ulcers, and all available treatment modalities can only reduce the frequency or severity of the lesions.

Oral mucosal keratinocytes express RANTES and ICAM-1, but not interleukin-8, in oral lichen planus and oral lichenoid reactions induced by amalgam fillings

Oral lichen planus (OLP) is a chronic inflammatory disease of the oral mucosa characterized by a band-like accumulation of lymphocytes in the connective tissue adjacent to the basement membrane as well as intraepithelially. Amalgam fillings can induce oral lichenoid reactions (OLR) that are similar to OLP. The adhesion molecule ICAM-1 and the chemokines interleukin-8 and RANTES all play central roles in leucocyte trafficking. The aim of this study was to investigate the possible role of these molecules in the migration of leucocytes into the oral mucosa in OLP and OLR. Standard immunoperoxidase techniques were used to visualize the expression of ICAM-1, RANTES and interleukin-8 in frozen biopsy sections. ICAM-1 was expressed by endothelial cells, but not by keratinocytes, in normal oral mucosa. ICAM-1 was expressed by keratinocytes in 11 of 12 biopsies of OLP and in six of seven biopsies of OLR. In all of these cases ICAM-1 was also expressed by endothelial cells and leucocytes. Although not present in normal oral mucosa, RANTES was expressed by keratinocytes in 21 of 24 biopsies of OLP and in seven of seven cases of OLR. Interleukin-8 was not detected in any of the samples. The expression of ICAM-1 and RANTES by epithelial keratinocytes in the oral mucosa in OLP and OLR could be a key inflammatory mechanism in these diseases.

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.

Activation of oral keratinocytes by mercuric chloride: relevance to dental amalgam-induced oral lichenoid reactions

BACKGROUND

Despite the benefits of mercury-containing amalgam dental fillings there are growing concerns regarding the potential adverse health effects arising from exposure to mercury released from fillings. In some individuals this process may result in a local lichenoid reaction of the oral mucosa.

OBJECTIVES

The aim of this study was to investigate the possibility that mercury salts released from amalgam fillings might act directly on oral keratinocytes to induce changes that could promote the development of such lesions.

METHODS

In vitro experiments were performed in which normal oral and cutaneous keratinocytes were cultured in the presence of mercuric chloride (HgCl2). ICAM-1 expression and the release of cytokines was determined by enzyme-linked immunosorbent assay techniques. T-cell binding to HgCl2-pretreated keratinocytes was assessed using a colorimetric method.

RESULTS

Subcytotoxic concentrations of HgCl2 induced a concentration-related increase in ICAM-1 expression and consequent T-cell binding on oral, but not cutaneous, keratinocytes. HgCl2 also stimulated the release of low levels of tumour necrosis factor-alpha and interleukin-8 (but not RANTES), and inhibited the release of interleukin-1alpha by oral keratinocytes.

CONCLUSIONS

This study provides evidence that oral keratinocytes may play an integral part in initiating the pathogenesis of amalgam-induced lichenoid reactions.

Recurrent aphthous stomatitis and smoking

BACKGROUND

Several studies have reported cigarette smoking to have a beneficial protective effect on recurrent aphthous stomatitis (RAS). In this study, we evaluated once again the incidence of smoking in RAS patients compared with controls. This study differs from most previous ones in that the patients were diagnosed by direct observation of active lesions by a dermatologist.

METHODS

Thirty-four patients with RAS who were seen at the dermatology clinic during a period of 2 years were compared with 115 outpatients with other skin diseases and 20 healthy hospital personnel who had no history of aphthae, with regard to their smoking habits.

RESULTS

Among the 34 patients with RAS, 8.8% were active smokers compared with a significantly higher percentage (25.2%) among the control subjects.

CONCLUSIONS

In agreement with others, we found a negative epidemiologic association between smoking and RAS. This finding can be used to clarify the cause and pathogenesis of the disease, and possibly to identify better treatment or preventive options than those currently available.

Autocytotoxic T-cell clones in lichen planus

We examined the in vitro cytotoxic activity of cutaneous T-cell lines and clones from lichen planus (LP) patients against autologous epidermal keratinocytes. T cells were cultured from LP lesions and adjacent clinically normal skin and cloned by limiting dilution. Keratinocytes were cultured from LP lesions and adjacent clinically normal skin and immortalized by transfection with the E6 and E7 genes from human papillomavirus 16 (HPV16). The lesional T-cell line from one LP patient contained 27% gammadelta+ T cells and was significantly more cytotoxic against autologous lesional keratinocytes than the T-cell line from clinically normal skin. Clones isolated from the lesional T-cell line were significantly more cytotoxic against autologous lesional keratinocytes than clones isolated from the non-lesional T-cell line. Most cytotoxic clones from LP lesions were CD8+ and most non-cytotoxic clones from LP lesions were CD4+. One cytotoxic clone was CD4- and CD8- and expressed the gammadelta T-cell receptor. Two CD8+ LP lesional T-cell clones showed dose-dependent killing of HPV16 E6/E7-immortalized autologous lesional and normal keratinocytes, but no cytotoxic activity against Epstein-Barr virus-transformed autologous B-cell blasts. The cytotoxic activity of CD8+ lesional T-cell clones against autologous lesional keratinocytes was partially blocked with anti-major histocompatibility complex (MHC) class I monoclonal antibodies. These data support the hypothesis that CD8+ lesional T cells recognize an antigen associated with MHC class I on lesional keratinocytes and that CD8+ cytotoxic T cells lyse keratinocytes in LP lesions.

Mechanisms of binding of cutaneous lymphocyte-associated antigen-positive and alphaebeta7-positive lymphocytes to oral and skin keratinocytes

Intraepithelial lymphocytes (IEL) utilize the integrin alphaebeta7 on their surface to bind to E-cadherin on epithelial cells in the gut and breast. In oral mucosa and skin IEL express alphaebeta7 and the cutaneous lymphocyte-associated antigen (CLA) but the mechanisms of adhesion of these subsets to keratinocytes are unknown. Levels of alphaebeta7 and CLA were up-regulated on peripheral blood lymphocytes (PBL) by transforming growth factor-beta (TGF-beta) and interleukin-12 (IL-12), respectively, and both groups of lymphocytes adhered onto oral and skin keratinocytes. Adhesion of IL-12-activated PBL was totally abolished by anti-lymphocyte-associated function antigen type 1 (anti-LFA-1) antibodies but was unaffected by anti-alphaebeta7 antibodies indicating that adhesion of the CLA-positive subset is mediated via LFA-1 interaction with intercellular adhesion molecule-1 (ICAM-1). Adhesion of TGF-beta-activated PBL to E-cadherin-positive oral and skin keratinocytes was partially inhibited by anti-alphaebeta7 antibodies but was unaffected by the blocking antibody E4.6 against E-cadherin which detects the binding site for alphaebeta7-positive lymphocytes in breast and gut epithelium. TGF-beta-activated PBL also bound to an E-cadherin-negative oral keratinocyte cell line and adhesion was inhibited by anti-alphaebeta7 antibodies. These results strongly suggest that in oral epithelium and epidermis alphaebeta7-positive lymphocytes do not bind to E-cadherin and there may be a novel second ligand for the alphaebeta7 integrin.

Induction of adhesion molecule expression on blood vessels and keratinocytes in recurrent oral ulceration

Adhesion molecules are known to play a crucial role in the recruitment of inflammatory cells to sites of inflammation. In this study endothelial cell and keratinocyte adhesion molecule expression in recurrent oral ulcers (ROU) (n = 13) was compared with that found in normal oral mucosa (NOM) (n = 11) and experimentally induced ulcers (EIU) (n = 5) by using immunohistochemistry. Significantly greater expression of both vascular cell adhesion molecule- (VCAM-1) and E-selectin was demonstrated on vasculature in ROU compared with that found in both NOM and EIU. Induction of keratinocyte intercellular adhesion molecule-1 (ICAM-1) was also a prominent feature of ROU. The expression of VCAM-1 and E-selectin on blood vessels in ROU is likely to be important in the accumulation of lymphocytes that characterise early aphthous lesions. The induction of keratinocyte ICAM-1 may facilitate lymphocyte invasion of the epithelium in ROU, which may ultimately result in ulcer formation.

Recurrent aphthous stomatitis

Recurrent aphthous stomatitis (RAS) is one of the most common oral mucosal disorders. Nevertheless, while the clinical characteristics of RAS are well-defined, the precise etiology and pathogenesis of RAS remain unclear. The present article provides a detailed review of the current knowledge of the etiology, pathogenesis, and management of RAS.

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.

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.

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.

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.

Recurrent aphthous stomatitis

Recurrent aphthous stomatitis (RAS) is the most common oral mucosal disease in North America. In some instances, RAS represents the central feature of the multisystem disease complex Behcet's syndrome. This article reviews the clinical features, contributing etiologic factors, and etiopathogenesis of RAS and Behcet's syndrome and describes therapeutic considerations and strategies essential to management of patients suffering from recurrent mouth ulcers.

The role of adhesion molecules in oral cancer

Cell-cell and cell-matrix interactions are mediated by adhesion molecules. By altering interactions between epithelial cells, extracellular matrix and leukocytes, changes in adhesion molecule expression can influence tumour development and metastasis. This study compared the adhesion molecule profile of oral squamous cell carcinoma (SCC) with normal buccal mucosa. The pattern of expression of adhesion molecules differed between normal epithelial cells and tumour cells, while leukocytes and endothelial cells adjacent to the tumour showed a pattern common to inflammatory sites. Aberrations in cell adhesion receptors on tumour cells may contribute to the unique biologic behaviour of individual tumours.

Expression of lymphocyte function-associated antigen 3 in oral lichen planus

OBJECTIVE

The expression pattern of lymphocyte function-associated antigen 3 (LFA-3) in the buccal mucosa of oral lichen planus (OLP) patients was compared to that of healthy controls to investigate the possible role of LFA-3 in cell interactions within OLP lesions.

MATERIALS AND METHODS

Samples of buccal mucosa from 17 clinically healthy individuals and 17 OLP lesions were analysed. Expression of LFA-3, CD2, CD3 and CD14 was visualized by an immunoperoxidase technique and assessed microscopically.

RESULTS

In healthy buccal mucosa LFA-3 was expressed on keratinocytes, Langerhans cells within the epithelium and on endothelial cells in the lamina propria. In OLP patients a similar pattern of LFA-3 staining was observed. In addition, cytoplasmic LFA-3 without accompanying surface staining, was seen on a subpopulation of macrophage-like cells. Substantial amounts of LFA-3 also appeared to be associated with non-cellular components of the extracellular matrix within the inflammatory infiltrate.

CONCLUSIONS

We have obtained evidence for a previously undescribed localization of LFA-3 within macrophages, and have observed that expression of LFA-3 is apparently elevated within OLP lesions. LFA-3 may play an important role in the pathogenesis of OLP.

Formation of normal gingival epithelial phenotypes around osseo-integrated oral implants in humans

The oral, oral sulcular, and junctional epithelia of the natural gingiva each possess distinct patterns of differentiation that are demonstrable both ultrastructurally and by their individual patterns of macromolecular synthesis. The supracrestal tissues reformed around oral implants structurally resemble those of natural gingiva but little is known about phenotype changes occurring in the epithelia. To investigate whether peri-implant epithelia acquire similar patterns of differentiation to those of natural gingiva, biopsies from the supracrestal regions of five oral implants were examined by immunofluorescent methods using a panel of monoclonal antibodies with specificities for individual cytokeratins and ICAM-1, macromolecules which act as markers of the three gingival epithelial phenotypes. The observed staining patterns indicated the formation of oral, oral sulcular, and junctional epithelia which were phenotypically indistinguishable from those of natural gingival epithelia. This degree of reprogramming of epithelial gene expression is a surprising observation and the potential mechanisms leading to the development of those new epithelial phenotypes are discussed in the context of what is known about the development of natural gingiva, in terms of the possible effects of inflammation, and in relation to the known connective tissue influences on epithelial differentiation.

ICAM-1-expressing pocket epithelium, LFA-1-expressing T cells in gingival tissue and gingival crevicular fluid as features characterizing inflammatory cell invasion and exudation in adult periodontitis

Activated T lymphocytes constitute a major component of inflammatory cells in the early periodontal lesion, and also appear in the gingival crevicular fluid. In an attempt to clarify the relationship between the ICAM-1 (CD54) expression of pocket epithelium in gingiva and the infiltrating lymphocyte population, we carried out an analysis of CD11a+(LFA-1 alpha), CD25+(IL-2R alpha) and CD4+(Th) cells subjacent to ICAM-1-expressing pocket epithelia and CD11a+CD25+CD4+ cells in gingival crevicular fluid (GCF). GCF was collected by crevicular washing from 16 patients with periodontitis (P group) and 3 subjects with healthy gingiva (H group). Peripheral blood (PB) was collected at the same time. Mononuclear cells were isolated by Ficoll-paque gradient centrifugation from GCF and PB. Monoclonal antibodies (mAb) to CD11a, CD25, and CD4 were used for three-color flow cytometry. Gingival biopsies were obtained from 7 patients in P group and 3 subjects in H group. Serial cryostat sections (6 microns in thickness) were prepared from each biopsy, on which a double staining was performed. The number of CD11a+CD25+CD4+ cells and the fluorescence intensity of FITC conjugated anti-CD11a were significantly higher in GCF than in PB (p < 0.001 to p < 0.01). CD11a+CD25+CD4+ cells were not detected in GCF in H group. The pocket epithelia expressed CD54 in P group, but not in H group. The number of CD11a+, CD25+ and CD4+ cells infiltrating the connective tissue subjacent to the upper, middle and lower parts of the CD54 positive pocket epithelium (n = 16) was 141 +/- 26, 38 +/- 13, 144 +/- 29 (cells/0.04 mm2), respectively, whereas in the CD54 negative pocket epithelium, it was (n = 5) 9 +/- 2, 3 +/- 1, 8 +/- 3. In P group, the CD11a+CD25+CD4+ cell number in GCF correlated with CD25+, CD11a+ cells in the connective tissue subjacent to the CD54+ pocket epithelium. These results indicate that expression of ICAM-1 in pocket epithelium is relevant to the migration of CD11a, CD25, CD4 positive cells in connective tissue subjacent to the pocket epithelium into the periodontal pocket. Assessing the relationship of our findings and other adhesion molecules would offer important clues to the understanding of T cell migration in affected gingiva.

The etiopathogenesis of Sjögren's syndrome

With increasing awareness and improved diagnostic tests, Sjögren's syndrome (SS) is becoming recognized as a common autoimmune disease, affecting as many as 3% of women over age 55 years. Apart from keratoconjunctivitis sicca, systemic features are common, leading to considerable morbidity and occasionally mortality. Predisposing factors for SS include HLA determinants that have been linked to DR3 and heterozygosity for DQ-1 and DQ-2. There is accumulating evidence that activated epithelial cells and their interaction with T cells play a central role in pathogenesis. Some restriction of T-cell receptor gene usage to V beta 6.7b and V beta 13.2 and a profile of cytokine production consistent with Th-1-type cells has been observed in affected tissues. Antibodies to Ro (SS-A) and La (SS-B) are found in about 50% of patients and are associated with more severe glandular and extraglandular manifestations. There is evidence that the antibodies are pathogenic, not only in patients, but in their infants born with congenital heart block. Studies of herpesviruses have led to conflicting results, and interest has recently focussed on retroviruses, based on the findings of the expression of retroviral elements in salivary glands of SS patients and antiretrovial antibodies in serum. Mice infected with or transgenic for retroviruses develop SS-like pathology and are currently being studied as animal models of the disease. In the last few years, considerable progress has been made in the understanding of the pathogenesis of SS, and the disease has become the prototype for the investigation of a viral etiology for autoimmune rheumatic disease. Study of its etiopathogenesis may be the key to understanding autoimmune disease in general.

Leukocyte adhesion molecules in oral lichen planus: a T cell-mediated immunopathologic process

Oral lichen planus exhibits features of a mucosal type IV immunopathologic process. Adhesion molecules involved in the trafficking and homing of T lymphocytes to the subepithelial compartment were assessed by immunohistochemical methods. Laminin, type IV collagen and type VII collagen extracellular matrix components at the epithelial-connective tissue junction are significantly increased and serve as ligands for beta 1 integrins on lymphocyte membranes. Endothelial-associated intercellular adhesion molecule 1 and extracellular matrix basement membrane components are also significantly increased in the submucosa. Keratinocyte expression of major histocompatibility complex class II molecules and intercellular adhesion molecule 1 may serve as ligands for lymphocyte T cell receptor complex and beta 2 integrins, respectively. These adhesion molecules are probably involved in the trafficking of lymphocytes to the epithelial connective tissue interface in response to as of yet undefined antigens.

VCAM-1 and ICAM-1 are expressed by Langerhans cells, macrophages and endothelial cells in oral lichen planus

Expression of intercellular adhesion molecule-1 (ICAM-1, CD54) and vascular cell adhesion molecule-1 (VCAM-1, CD106) was examined in oral lichen planus (OLP) and normal oral mucosa (NOM). Immunoperoxidase staining showed ICAM-1 expression by vascular endothelium in all biopsies of OLP and NOM whereas endothelial VCAM-1 staining was found in 2/7 NOM and 8/9 OLP. In the lamina propria of NOM occasional cells were ICAM-1 or VCAM-1 positive, and virtually no staining of intraepithelial dendritic cells was seen for either marker. Intraepithelial dendritic cells stained for ICAM-1 in 7/9 and VCAM-1 in 4/9 OLP biopsies. Double immunofluorescence showed dual labelling of Langerhans cells (LC) with CD1a and VCAM-1 in a further 5/12 cases of OLP, but there was no such staining in four NOM. This is the first report of LC staining with VCAM-1. Induction of ICAM-1 and VCAM-1 on LC and macrophages in OLP suggests these cells are activated and may contribute to the pathogenesis of OLP by presenting antigen to infiltrating lymphocytes.

Immunopathology of oral mucosal ulcerative, desquamative, and bullous diseases. Selective review of the literature

Cell/cell and cell/matrix adhesion proteins are responsible for maintaining the integrity of the mucosal lining of the oral cavity. Disease processes that destroy keratinocytes or adversely affect their adhesion to one another or to the subjacent basement membrane will result in erosions, ulcerations, and desquamations. Immunologic processes that have a deleterious effect on the integrity of the epithelial/basement membrane/submucosa complex are reviewed, and current research findings with respect to pathogenesis are discussed. In particular, T-cell-mediated hypersensitivity is involved in recurrent aphthous stomatitis and lichen planus; humoral-mediated immunity to cadherin intercellular adhesion molecules is important in the process of acantholysis in pemphigus vulgaris, and genetic defects and antibody-mediated processes give rise to junctional separation in epidermolysis bullosa and mucous membrane pemphigoid, respectively. An immune complex mechanism appears to underlie the pathogenesis of erythema multiforme.

Increased submucosal factor XIIIa-positive dendrocytes in oral lichen planus

Factor XIIIa+ "dendrocytes", normal residents of the submucosa and dermis, are a morphologically and phenotypically distinctive subset of the monocyte-macrophage system. Because these cells are believed to participate in the regulation of immune responses, we postulated that they may play a role in the pathogenesis of lichen planus, a condition of immune dysregulation. Tissue sections of oral lichen planus were evaluated immunohistochemically for evidence of differences in dendrocyte populations in lesional and non-lesional areas from the same patient. In addition to factor XIIIa, sections were stained for antigens (CD68, S-100 protein, CD36) that may be expressed by other cells that occasionally exhibit dendritic profiles. CD18 (found on leukocytes and dendrocytes) and its ligand ICAM-1 (intercellular adhesion molecule) were also identified in sections to determine if these antigens are operative in lichen planus. Results showed that XIIIa+ dendrocytes were significantly increased in number (and size) in lichen planus. The mean number of dendrocytes in connective tissue subjacent to basement membrane (0.064 mm2) was 27 in lichen planus as compared to 10 in adjacent unaffected tissue. Similar increases were also evident in connective tissue deep to this zone (mean of 20 dendrocytes vs. mean of 8). CD68+ macrophages were also abundant in the lichen planus infiltrate, and S-100+ connective tissue cells were frequently seen. CD36+ dendritic cells were seen in relatively small numbers in the same sites where dendrocytes were found. ICAM-1+ connective tissue dendritic cells of undetermined lineage were also evident in the diseased areas.(ABSTRACT TRUNCATED AT 250 WORDS)

Adhesion molecule expression in chronic inflammatory periodontal disease tissue

Differences in lymphocyte populations have been demonstrated in gingivitis and periodontitis lesions. A differential expression of adhesion molecules may play a role in lymphocyte trafficking in these tissues. An indirect avidin biotin immunoperoxidase technique was used to stain a range of adhesion molecules in tissue sections of 21 gingival biopsies from both gingivitis and periodontitis subjects. These specimens were placed into three groups according to the size of the infiltrate. ICAM-1, PECAM-1 and LECAM-1 expression on mononuclear cells in the inflammatory infiltrates increased significantly with increasing size of infiltrate. Approximately 50% of these mononuclear cells were LFA-1+ and CD29+. When specimens were grouped according to their putative disease status there were no significant differences between mononuclear cell adhesion molecule expression in small infiltrates from either gingivitis or adult periodontitis subjects. This was also the case with larger lesions from both clinical groups. Therefore there does not appear to be a differential expression of adhesion molecules on lymphocytes in gingivitis and periodontitis tissue. Endothelial cells were positive for ICAM-1, PECAM-1, CD29, GMP-140 but negative for ELAM-1. Keratinocyte expression of ICAM-1 increased with increasing size of infiltrate although in heavy infiltrates, cells in the region of the junctional epithelium which were positive in small lesions, became ICAM-1 negative. The upper layers of the oral epithelium were positive for LECAM-1 in small infiltrates and with increasing size of infiltrate, the lower layers and many of the sulcular and junctional epithelium keratinocytes were positive.(ABSTRACT TRUNCATED AT 250 WORDS)

A study of macrophages, macrophage-related cells, and endothelial adhesion molecules in recurrent aphthous ulcers in HIV-positive patients

The purpose of this immunohistochemical study was to investigate the presence and distribution of macrophages (CD11c+ and CD68+) and macrophage-related dendritic cells (factor XIIIa+ and CD36+) in early and late aphthous ulcers associated with HIV infection. To substantiate a mechanism by which these cells may move from the vascular compartment to tissue spaces, we also investigated expression of ELAM (endothelial leukocyte adhesion molecule), ICAM-1 (intercellular adhesion molecule), and CD18 (leukocyte function antigen). Numerous CD11c+ and CD68+ macrophages were seen in early lesions, though larger numbers of CD68+ cells were present in older lesions. No significant increases in factor XIIIa+ dendrocytes were seen in either early or late lesions, though dendrocytes appeared enlarged. CD36+ cells and CD18+ leukocytes were more numerous in early than in late aphthous ulcers. ELAM and ICAM expression was most intense on endothelial cells in early aphthous ulcers, with staining intensity fading toward the lesion periphery. Control specimens showed weaker ELAM and ICAM staining than did the ulcer specimens. Keratinocytes did not express ICAM. By virtue of their numbers, macrophages and macrophage subtypes appear to have a significant role in both the early and late stages of this disease. Although factor XIIIa-expressing dendrocytes may not have been more numerous in the ulcers, they appeared to be "activated" because of their prominence in the lesions and their occasional co-expression of CD68 antigen (KP1+). They may have a minor role in antigen processing, phagocytosis, and fibroplasia. ELAM and ICAM expression by endothelial cells provides a mechanism by which macrophages and other leukocytes can be recruited to the site of the lesion.(ABSTRACT TRUNCATED AT 250 WORDS)

Disease mechanisms in oral lichen planus. A possible role for autoimmunity

Current evidence for the involvement of cell-mediated immunological mechanisms in the pathogenesis of oral lichen planus is reviewed. Both a spatial and temporal relationship between cytotoxic T Lymphocytes and epithelial damage have been reported. Although keratinocytes appear to be the target for destruction in oral lichen planus, their role in antigen presentation is unclear. We propose that in oral lichen planus patients, diverse exogenous agents such as drugs, trauma and infection, stimulate the expression of a common self molecule by oral mucosal keratinocytes. An autoimmune reaction by cytotoxic T lymphocytes to these activated keratinocytes may result in the tissue destruction which is characteristic of oral lichen planus.