The high expression level of programmed death-1 ligand 2 in oral lichen planus and the possible costimulatory effect on human T cells

A Molecular Hypothesis on Malignant Transformation of Oral Lichen Planus: A Systematic Review and Meta-Analysis of Cancer Hallmarks Expression in This Oral Potentially Malignant Disorder

We aimed to qualitatively and quantitatively analyze, through a systematic review and meta-analysis, the current evidence on the differential expression of the hallmarks of cancer in oral lichen planus (OLP) samples, in order to know the earliest molecular mechanisms that could be involved in the malignant transformation of this oral potentially malignant disorder. We searched MEDLINE/PubMed, Embase, Web of Science, and Scopus for studies published before November 2023. We evaluated the methodological quality of studies and carried out meta-analyses to fulfill our objectives. Inclusion criteria were met by 110 primary-level studies, with 7065 OLP samples, in which the expression of 104 biomarkers were analyzed through immunohistochemistry. Most OLP samples showed sustained cell proliferation signaling (65.48%, 95%CI = 51.87-78.02), anti-apoptotic pathways (55.93%, 95%CI = 35.99-75.0), genome instability (48.44%, 95%CI = 13.54-84.19), and tumor-promoting inflammation events (83.10%, 95%CI = 73.93-90.74). Concurrently, OLP samples also harbored tumor growth suppressor mechanisms (64.00%, 95%CI = 53.27-74.12). In conclusion, current evidence indicates that molecular mechanisms promoting hyperproliferative signaling, an antiapoptotic state with genomic instability, and an escape of epithelial cells from immune destruction, are developed in LP-affected oral mucosa. It is plausible that these events are due to the actions exerted by the chronic inflammatory infiltrate. Malignant transformation appears to be prevented by tumor suppressor genes, which showed consistent upregulation in OLP samples.

Updates on immunological mechanistic insights and targeting of the oral lichen planus microenvironment

Oral lichen planus (OLP) is a chronic immune inflammatory disease that is an oral potentially malignant disorder (OPMD), occurs in the oral mucosa and affects approximately 0.5% to 4% of the general population. There are usually five types of OLP: reticular/papular, plaque-like, atrophic/erythematous, erosive/ulcerative, and bullous. Furthermore, the chance of causing oral squamous cell carcinoma (OSCC) is 1.4%. Although the etiology of OLP is still unknown, accumulating evidence supports that immune dysregulation may play a vital role in the pathogenesis of OLP, especially the massive production of various inflammatory cells and inflammatory mediators. In this review, we focus on the relationship between OLP and its immune microenvironment. We summarize current developments in the immunology of OLP, summarizing functional cell types and crucial cytokines in the OLP immune microenvironment and the underlying mechanisms of key signaling pathways in the OLP immune microenvironment. We highlight the application potential of targeted immune microenvironment therapy for OLP.

Severe oral ulcerative and lichenoid lesions associated with adrenal insufficiency in a patient treated with nivolumab: Report of a case and review of literature

Nivolumab, an antibody against anti-programmed death type 1, has been used for treatment of advanced non-small cell lung cancer with improvement of overall survival. Usually, diarrhea, cutaneous rash, and pruritus are reported as the most common immune-related adverse effects of nivolumab therapy. Oral lesions and secondary adrenal insufficiency sometimes occur but usually are rare events. We report a case of a patient treated with nivolumab who then showed persistent oral ulcerative and lichenoid lesions, which were refractory to topical corticosteroids. The oral lesions were concomitant to nivolumab-induced adrenal insufficiency. These adverse events led to nivolumab discontinuation, which favored oral lesion healing and adrenal insufficiency remission. Through a brief review of the literature concerning nivolumab toxicity in the oral cavity, we discuss the clinical aspect and management of these lesions.

Abnormal membrane-bound and soluble programmed death ligand 2 (PD-L2) expression in systemic lupus erythematosus is associated with disease activity

Programmed death ligand (PD-L) 2 and PD-L1 are the second and first ligands, respectively, for programmed cell death-1 protein (PD-1), which is one of the key factors responsible for inhibitory T cell signaling, mediating mechanisms of tolerance and providing immune homeostasis. Studies have shown that PD-1 and its ligand PD-L1 are abnormally expressed in autoimmune diseases, such as rheumatoid arthritis and autoimmune hepatitis, but its other ligand, PD-L2, has rarely been studied. This study analyzed the changes in membrane-bound PD-L2 expression in peripheral blood mononuclear cells and soluble PD-L2 (sPD-L2) levels in the serum of patients with systemic lupus erythematosus (SLE) to explore the relationship between PD-L2 expression with disease activity and related test parameters. Our results showed that membrane-bound PD-L2 expression on monocytes was significantly higher and the sPD-L2 levels were significantly lower in SLE patients than in healthy subjects. Patients with active SLE accompanied by lupus nephritis, joint pain, and clinical manifestations of oral ulcers had relatively low secretion of sPD-L2. In addition, this secretion level was significantly and positively correlated with complement components 3 and 4 (C3/C4). These results suggest that PD-L2 may be a promising biomarker associated with the pathogenesis of SLE.

Evaluation of PD-L1, PD-L2, PD-1 and cytotoxic immune response in oral lichen planus

OBJECTIVE

To investigate the expression of programmed death-ligands 1 and 2 (PD-L1, PD-L2), programmed death-1 (PD-1), CD8 and granzyme B (GrB), as well as its correlation with the severity of oral lichen planus (OLP).

MATERIALS AND METHODS

In a collaborative study, 33 cases of OLP were evaluated according to the latest criteria proposed by the American Academy of Oral and Maxillofacial Pathology (AAOMP/2016) and were submitted to immunohistochemistry. Positivity was measured semiquantitatively (PD-L1, PD-L2) and quantitatively (PD-1, CD8, GrB). The severity of OLP was assessed according to clinical subtype, symptomatology and response to corticosteroid therapy.

RESULTS

Most OLPs were considered to be negative for PD-L1 (66.6%), but high expression of PD-L2 (96.9%) by keratinocytes and immunoinflammatory cells was observed. PD-1⁺ cell density/mm² was reduced compared to CD8⁺ cells. A low cytotoxic immune response (CD8:GrB ratio) was also demonstrated. Interestingly, there were fewer GrB⁺ cells in the intraepithelial region in reticular OLP compared to erosive/bullous OLP.

CONCLUSIONS

PD-L1/PD-1 pathways appear to be compromised in OLP due to low PD-L1 expression in most samples. In contrast, PD-L2 overexpression associated with a possible regulation of the cytotoxic immune response suggests an immune tolerance that may contribute to the chronic profile of OLP.

Immune Checkpoint Inhibitors in Oral Cavity Squamous Cell Carcinoma and Oral Potentially Malignant Disorders: A Systematic Review

Cancers of the oral cavity cause significant cancer-related death worldwide. While survival rates have improved in recent years, new methods of treatment are being investigated to limit disease progression and to improve outcomes, particularly in oral cavity squamous cell carcinoma (OSCC) and oral potentially malignant disorders (OPMD). The emerging treatment modality of immunotherapy targets immune checkpoint molecules including PD-1 and its ligand PD-L1, CTLA-4, LAG-3, and TIM-3 to enhance the host immune response against tumours, and to limit the growth and progression of cancer cells. In this systematic review, we searched five databases for keywords pertaining to oral cancers and OPMDs, along with immune checkpoint inhibitors, in order to summarize the current status of their use and efficacy in these diseases. A total of 644 different articles were identified between 2004 and 2019, with 76 deemed suitable for inclusion in the study, providing a total of 8826 samples. Combined results show expression of PD-1 and PD-L1 in the majority of OPMD and OSCC samples, with expression correlating with increased progression and decreased survival rates. Immunotherapy agents pembrolizumab and nivolumab target PD-1 and have been shown to prolong survival rates and improve disease outcomes, especially in combination with chemotherapy or radiotherapy. Despite the equivocal nature of current evidence, there is support for the prognostic and predictive value of immune checkpoint molecules, especially PD-L1, and many studies provide support for the effective use of immune checkpoint inhibitors in the management of OSCC. Limited data is available for OPMD, therefore this should be the focus of future research.

An update of knowledge on PD-L1 in head and neck cancers: Physiologic, prognostic and therapeutic perspectives

Programmed cell death-ligand 1 (PD-L1) is a transmembrane protein that acts as a co-inhibitory factor in the immune response. Its receptor, programmed cell death protein 1 (PD-1), is found on immune cells, where binding to PD-L1 can reduce the proliferation of PD-1-positive cells, inhibit their cytokine secretion and induce apoptosis. PD-L1 in immune-privileged tissue plays a crucial role in peripheral tolerance. PD-L1 can be overexpressed in various malignancies, including oral squamous cell carcinoma, where it can attenuate the host immune response to tumour cells and has been associated with a worse prognosis. Monoclonal antibody therapies targeting the PD-1:PD-L1 axis have shown initial promise, but further research is needed to identify which patients will benefit. We provide an update of knowledge on PD-L1, including its structure, function and regulation. We also review studies on the overexpression of PD-L1 in cancer, specifically oral squamous cell carcinoma, and explore its potential value as a therapeutic target.

Immunohistochemical analysis of lichenoid reactions in patients treated with anti-PD-L1 and anti-PD-1 therapy

BACKGROUND

Recent advances in the immunotherapeutic treatment of cancer have led to the development of multiple new directed therapies including monoclonal antibodies that block the immune checkpoint T-cell receptor programmed death 1 (PD-1) and the PD-1 ligand, programmed death ligand 1 (PD-L1). Various immune-related toxicities have been associated with these drugs including, most commonly, skin rashes.

METHODS

Five cases of lichenoid dermatitis, including one case of lichenoid mucositis and one case of lichen sclerosus, associated with anti-PD-L1 and anti-PD1 therapy were compared with three biopsies of non-drug-related lichen planus (LP) and three lichen planus-like keratoses (LPLK) used as controls.

RESULTS

Histopathologic and immunophenotypic analysis of these lichenoid lesions demonstrated significantly greater histiocytic infiltrates than observed in control lichenoid reactions (p = 0.0134). We also observed increased spongiosis and epidermal necrosis. No significant differences were seen in expression of CD3, CD4:CD8, CD20, PD-1, CD25, Foxp3, CXCL13 and PD-L1 expression.

CONCLUSIONS

These findings expand the literature of immune-related toxicities of PD-L1 and PD-1 blockade to include lichenoid dermatitis and lichenoid mucositis. Of note, these cutaneous side effects were amenable to topical treatment, without the need for medication dose reduction or discontinuation.

Inflammation-related cytokines in oral lichen planus: an overview

Cytokines are powerful mediators which play a central role in both innate and adapted immune responses. Aberrant productions of cytokines may lead to the onset of immune deficiency, allergy or autoimmunity, which are involved in the mechanisms of various immune-mediated inflammatory diseases. Oral lichen planus (OLP) is a chronic inflammation disease affecting the oral mucosa with unknown aetiology. Previous studies have described the abnormal expression patterns of various inflammation-related cytokines, such as IL-1, 2, 4, 5, 6, 8, 10, 12, 17, 18, TGF-β, IFN-γ and TNF-α, in lesions, saliva, serum and peripheral blood mononuclear cells from patients with OLP, which may reflect the immune dysregulation status and emerge as central players in the immunopathogenesis of OLP. Besides, the gene polymorphisms of several cytokines such as IFN-γ, TNF-α, IL-4, IL-10 have been found to be involved in the susceptibility of OLP. In this review, we gave a brief introduction of the characteristics and biological functions of these inflammation-related cytokines and summarized for the first time the current knowledge on the involvement of inflammation-related cytokines in OLP. Further research on the exact roles of these cytokines will aid the understanding of the pathogenesis and the identification of novel therapeutic approaches of OLP.

Altered microRNA expression profile with miR-27b down-regulation correlated with disease activity of oral lichen planus

BACKGROUND

Increasing evidence indicates that microRNAs (miRNAs) play a vital role in the pathogenesis of inflammatory and autoimmune diseases. The objective of this study was to investigate the altered miRNA expression profile in patients with oral lichen planus (OLP) and determine the miR-27b expression.

METHODS

We compared miRNA expression patterns in oral biopsy specimens from patients with OLP (n=3) with those from normal controls (n=3) using microarray technology. We further assessed the miR-27b expression in specimens from patients with OLP (n=53) against controls (n=34) using real-time quantitative PCR (RT-QPCR), and miR-27b expression in specimens from patients with OLP (n=15) against controls (n=12) using in situ hybridization (ISH).

RESULTS

Using microarray analysis, a total of 46 differentially expressed miRNAs with more than 2-fold change were identified, including 8 up-regulated and 38 down-regulated miRNAs. Both RT-QPCR and ISH analyses revealed that miR-27b was significantly down-regulated in OLP tissue, and miR-27b expression was even more suppressed in atrophic-erosive OLP than in reticular OLP. In addition, miR-27b was found to be expressed in the epithelial keratinocyte layer of both normal and OLP tissues.

CONCLUSION

These data indicate that miRNAs may be the novel candidate biomarkers for the implication of miRNAs in the pathogenesis of OLP.