Langerhans cell number is a strong and independent prognostic factor for head and neck squamous cell carcinomas

The role of the epithelial sentinels, Langerhans cells and γδT cells, in oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) arises in the oral epithelium, a tissue in which immune surveillance is mediated by its primary resident leukocytes, Langerhans cells (LCs), and γδT cells. Under steady-state conditions, LCs and γδT cells play a critical role in maintaining oral mucosal homeostasis. As antigen-presenting cells of stratified epithelia, LCs respond to various challenges faced by the epithelium, orchestrating innate, and adaptive immune responses in order to resolve them. γδT cells also sense diverse epithelial insults and react rapidly through cytokine production and cytolytic activity. These epithelial sentinels are also considered to be the first leukocytes in the oral epithelium to encounter early carcinogenic events that have the potential of becoming OSCC. As evident in many malignancies, leukocyte populations help prevent cancer development although they also promote tumor progression. OSCC is no exception, as studies have reported both anti- and pro-tumor roles of LCs and γδT cells. In this review, we summarize the ontogeny of LCs and γδT cells in the oral epithelium and discuss their role in OSCC.

The Immune Cells in the Development of Oral Squamous Cell Carcinoma

A still unresolved issue surrounding tumor formation concerns the role that the immune system plays in preventing the formation and progression of neoplasia, including oral squamous cell carcinoma (OSCC). Antitumor immunity has historically been seen as a critical barrier for cancer cells to develop, grow and spread, and this can be modulated using immunotherapies to achieve antitumor clinical responses. However, it has recently become clear that tumor-associated immunity, particularly the inflammatory microenvironment, has the paradoxical effect of enhancing tumorigenesis and progression. In this review, we discuss the multifaceted function of infiltrating immune cells in suppressing or promoting premalignancy and cancer. In particular, we report on the evidence supporting a role for T lymphocytes, dendritic cells, macrophages, and neutrophils in the development and progression of oral potentially malignant disorders (OPMD) and OSCC. We also draw attention to the clinical relevance of immune cell phenotypes and associated molecules for use as biomarkers and to the translatability of current research findings to improve classification systems and precision medicine in patients with OSCC.

Precancerous Lesions of the Head and Neck Region and Their Stromal Aberrations: Piecemeal Data

Head and neck squamous cell carcinomas (HNSCCs) develop through a series of precancerous stages from a pool of potentially malignant disorders (PMDs). Although we understand the genetic changes that lead to HNSCC, our understanding of the role of the stroma in the progression from precancer to cancer is limited. The stroma is the primary battleground between the forces that prevent and promote cancer growth. Targeting the stroma has yielded promising cancer therapies. However, the stroma at the precancerous stage of HNSCCs is poorly defined, and we may miss opportunities for chemopreventive interventions. PMDs already exhibit many features of the HNSCC stroma, such as inflammation, neovascularization, and immune suppression. Still, they do not induce cancer-associated fibroblasts or destroy the basal lamina, the stroma's initial structure. Our review aims to summarize the current understanding of the transition from precancer to cancer stroma and how this knowledge can reveal opportunities and limitations for diagnostic, prognostic, and therapeutic decisions to benefit patients. We will discuss what may be needed to fulfill the promise of the precancerous stroma as a target to prevent progression to cancer.

Macrophages CD163+ and Factor XIIIa+ Provide a First-Line Defence against Proliferative Verrucous Leukoplakia Antigens

This study aimed to evaluate the density of the dendritic cells (DCs) and macrophages in oral leukoplakia (OL) and proliferative verrucous leukoplakia (PVL) by immunohistochemical analysis. We analysed paraffined tissue samples of PVL (n = 27), OL (n = 20), and inflammatory fibrous hyperplasia (n = 20) as the control group using the immunomarkers for DCs (CD1a, CD207, CD83, CD208 and CD123) and macrophages (CD68, CD163, FXIIIa and CD209). A quantitative analysis of positive cells in the epithelial and subepithelial areas was determined. Our results showed a reduction in CD208+ cells in the subepithelial area of the OL and PVL compared to the control. Additionally, we found a higher density of FXIIIa+ and CD163+ cells in the subepithelial area in PVL compared to the OL and control. Four-way MANOVA revealed a relationship between increased CD123+ cell density in the subepithelial area of “high-risk” samples regardless of disease. Macrophages provide the first line of defence against PVL antigens, suggesting a distinct pattern of innate immune system activation in PVL compared to OL, which may contribute to the complexity and the high rate of malignant transformation in the PVL.

Improving head and neck cancer therapies by immunomodulation of the tumour microenvironment

Targeted immunotherapy has improved patient survival in head and neck squamous cell carcinoma (HNSCC), but less than 20% of patients produce a durable response to these treatments. Thus, new immunotherapies that consider all key players of the complex HNSCC tumour microenvironment (TME) are necessary to further enhance tumour-specific T cell responses in patients. HNSCC is an ideal tumour type in which to evaluate immune and non-immune cell differences because of two distinct TME aetiologies (human papillomavirus (HPV)-positive and HPV-negative disease), multiple anatomic sites for tumour growth, and clear distinctions between patients with locally advanced disease and those with recurrent and/or metastatic disease. Recent technological and scientific advancements have provided a more complete picture of all cellular constituents within this complex TME and have evaluated the interplay of both immune and non-immune cells within HNSCC. Here, we include a comprehensive analysis of the complete ecosystem of the HNSCC TME, performed utilizing data-rich resources such as The Cancer Genome Atlas, and cutting-edge techniques, such as single-cell RNA sequencing, high-dimensional flow cytometry and spatial multispectral imaging, to generate improved treatment strategies for this diverse disease.

Phenotypes and Functions of Human Dendritic Cell Subsets in the Tumor Microenvironment

Dendritic cells (DCs) play a key role in the antitumor immunity, as they are at the interface of innate and adaptive immunity. This important task can only be performed thanks to the broad range of mechanisms that DCs can perform to activate other immune cells. As DCs are well known for their outstanding capacity to prime and activate T cells through antigen presentation, DCs were intensively investigated during the past decades. Numerous studies have identified new DC subsets, leading to a large variety of subsets commonly separated into cDC1, cDC2, pDCs, mature DCs, Langerhans cells, monocyte-derived DCs, Axl-DCs, and several other subsets. Here, we review the specific phenotypes, functions, and localization within the tumor microenvironment (TME) of human DC subsets thanks to flow cytometry and immunofluorescence but also with the help of high-output technologies such as single-cell RNA sequencing and imaging mass cytometry (IMC).

Immune Cell Density Evaluation Improves the Prognostic Values of Staging and p16 in Oropharyngeal Cancer

The incidence of oropharyngeal cancers (OPSCCs) has continued to rise over the years, mainly due to human papillomavirus (HPV) infection. Although they were newly reclassified in the last TNM staging system, some groups still relapse and have poor prognoses. Based on their implication in oncogenesis, we investigated the density of cytotoxic and regulatory T cells, macrophages, and Langerhans cells in relation to p16 status, staging and survival of patients. Biopsies from 194 OPSCCs were analyzed for HPV by RT-qPCR and for p16 by immunohistochemistry, while CD8, FoxP3, CD68 and CD1a immunolabeling was performed in stromal (ST) and intratumoral (IT) compartments to establish optimal cutoff values for overall survival (OS). High levels of FoxP3 IT and CD1a ST positively correlated with OS and were observed in p16-positive and low-stage patients, respectively. Then, their associations with p16 and TNM were more efficient than the clinical parameters alone in describing patient survival. Using multivariate analyses, we demonstrated that the respective combination of FoxP3 or CD1a with p16 status or staging was an independent prognostic marker improving the outcome of OPSCC patients. These two combinations are significant prognostic signatures that may eventually be included in the staging stratification system to develop personalized treatment approaches.

The association of cervicovaginal Langerhans cells with clearance of human papillomavirus

Human papillomavirus (HPV) clearance is important in eliminating cervical cancer which contributes to high morbidity and mortality in women. Nevertheless, it remains largely unknown about key players in clearing pre-existing HPV infections. HPV antigens can be detected by the most important cervical antigen-presenting cells (Langerhans cells, LCs), of which the activities can be affected by cervicovaginal microbiota. In this review, we first introduce persistent HPV infections and then describe HPV-suppressed LCs activities, including but not limited to antigen uptake and presentation. Given specific transcriptional profiling of LCs in cervical epithelium, we also discuss the impact of cervicovaginal microbiota on LCs activation as well as the promise of exploring key microbial players in activating LCs and HPV-specific cellular immunity.

Immunoscore Combining CD8, FoxP3, and CD68-Positive Cells Density and Distribution Predicts the Prognosis of Head and Neck Cancer Patients

We assessed immune cell infiltrates to develop an immunoscore for prognosis and to investigate its correlation with the clinical data of patients with head and neck cancer. CD8, FoxP3, and CD68 markers were evaluated by immunohistochemistry in 258 carcinoma samples and positive cells were counted in stromal and intra-tumoral compartments. The RStudio software was used to assess optimal cut-offs to divide the population according to survival while the prognostic value was established by using Kaplan–Meier curves and Cox regression models for each immune marker alone and in combination. We found with univariate analysis that the infiltration of immune cells in both compartments was predictive for recurrence-free survival and overall survival. Multivariate analysis revealed that CD8+ density was an independent prognostic marker. Additionally, the combination of CD8, FoxP3, and CD68 in an immunoscore provided a significant association with overall survival (p = 0.002, HR = 9.87). Such an immunoscore stayed significant (p = 0.018, HR = 11.17) in a multivariate analysis in comparison to tumor stage and histological grade, which had lower prognostic values. Altogether, our analysis indicated that CD8, FoxP3, and CD68 immunoscore was a strong, independent, and significant prognostic marker that could be introduced into the landscape of current tools to improve the clinical management of head and neck cancer patients.

Decreased CD1a + and CD83 + cells in tonsillar squamous cell carcinoma regardless of HPV status

Dendritic cells (DCs) are specialized antigen-presenting cells that play a critical role in the immune response against human papillomavirus (HPV) infection, and represent a therapeutic target in cancer.

Early-onset oral cancer as a clinical entity: aetiology and pathogenesis

Oral squamous cell carcinoma (OSCC) is one of the most important medical and socio-economic problems in many of the developed countries worldwide, due to the high mortality. The incidence of OSCC among individuals under 45 years of age is growing every year; however, the aetiological factors and pathogenetic mechanisms are poorly understood. This review summarizes the available information regarding clinicopathological features, extrinsic and intrinsic aetiological factors, and the molecular and immune landscape of early-onset OSCC. This cancer shows high recurrence rates and is not associated with the aetiological factors specific to adult-onset OSCC. Young adults with OSCC are not infected with human papillomavirus and rarely consume alcohol or tobacco, but more frequently use smokeless tobacco. Data from single studies indicate the hereditary nature of early-onset OSCC: the KIR2DL1⁺-HLA-C2⁺ genotype and MMP-1 2 G allele are frequently detected in young patients. Early-onset OSCC shows specific genetic, epigenetic, transcriptomic, and proteomic changes. The tumour microenvironment in early-onset OSCC is tolerogenic rather than immunogenic. All of the data suggest that OSCC in young patients is a separate clinical entity with a specific aetiology and pathogenesis. Further studies are needed to reveal the causes and molecular targets of early-onset OSCC for the development of preventive and therapeutic strategies.

Early antitumor activity of oral Langerhans cells is compromised by a carcinogen

Early diagnosis of oral squamous cell carcinoma (OSCC) remains an unmet clinical need. Therefore, elucidating the initial events of OSCC preceding tumor development could benefit OSCC prognosis. Here, we define the Langerhans cells (LCs) of the tongue and demonstrate that LCs protect the epithelium from carcinogen-induced OSCC by rapidly priming αβT cells capable of eliminating γH2AX⁺ epithelial cells, whereas γδT and natural killer cells are dispensable. The carcinogen, however, dysregulates the epithelial resident mononuclear phagocytes, reducing LC frequencies, while dendritic cells (DCs), macrophages, and plasmacytoid DCs (pDCs) populate the epithelium. Single-cell RNA-sequencing analysis indicates that these newly differentiated cells display an immunosuppressive phenotype accompanied by an expansion of T regulatory (Treg) cells. Accumulation of the Treg cells was regulated, in part, by pDCs and precedes the formation of visible tumors. This suggests LCs play an early protective role during OSCC, yet the capacity of the carcinogen to dysregulate the differentiation of mononuclear phagocytes facilitates oral carcinogenesis.

A model of impaired Langerhans cell maturation associated with HPV induced epithelial hyperplasia

Langerhans cells (LC) are skin-resident antigen-presenting cells that regulate immune responses to epithelial microorganisms. Human papillomavirus (HPV) infection can promote malignant epithelial transformation. As LCs are considered important for controlling HPV infection, we compared the transcriptome of murine LCs from skin transformed by K14E7 oncoprotein and from healthy skin. We identified transcriptome heterogeneity at the single cell level amongst LCs in normal skin, associated with ontogeny, cell cycle, and maturation. We identified a balanced co-existence of immune-stimulatory and immune-inhibitory LC cell states in normal skin that was significantly disturbed in HPV16 E7-transformed skin. Hyperplastic skin was depleted of immune-stimulatory LCs and enriched for LCs with an immune-inhibitory gene signature, and LC-keratinocyte crosstalk was dysregulated. We identified reduced expression of interleukin (IL)-34, a critical molecule for LC homeostasis. Enrichment of an immune-inhibitory LC gene signature and reduced levels of epithelial IL-34 were also found in human HPV-associated cervical epithelial cancers.

•

Single cell atlas of Langerhans cells in cutaneous skin

•

Stimulatory and inhibitory Langerhans cell states are in balance

•

Inhibitory Langerhans cell states dominate HPV-transformed hyperplastic skin

•

Langerhans cell imbalance is associated with disrupted IL-34 signaling

Impact of smoking on dendritic cells in patients with oral squamous cell carcinoma

Smoking has been shown to alter innate and adaptive immune responses and is directly associated with the onset of oral squamous cell carcinoma (OSCC). The purpose of this study was to evaluate the effect of cigarette smoke exposure on dendritic cells (DCs) from OSCC patients. CD1a and CD83 antibodies were used to identify immature and mature DCs, respectively, by immunohistochemistry in OSCC samples of 24 smokers and 24 non-smokers. Density of DCs was calculated in intra and peritumoral areas. Clinical and microscopic findings were reviewed and analyzed for all patients. Smokers with OSCC had a lower density of intra and peritumoral DCs when compared to non-smokers. Tumors classified as moderately/poorly differentiated had lower peritumoral CD1a+ DCs than well-differentiated tumors (p < 0.001). Smoking contributed to a depletion of immature and mature DCs in the OSCC.

Tumor microenvironment is not an 'innocent bystander' in the resistance to treatment of head and neck cancers (Review)

Head and neck cancers are still one of the most common types of cancer in the world. They rank in the leading sixth place in terms of incidence globally, and the incidence continues to rise. The mortality rates remain at high levels. Pathological subclassification places squamous cell carcinoma of the head and neck (HNSCC) in the first place concerning the histological forms of head and neck cancers; a tumor with extremely aggressive behavior and high mortality rates. The tumor microenvironment is a very complex ecosystem of cellular and non-cellular components, characterized by unique features, that contribute to the appearance of immunosuppression and diminished anticancer immunity, impacting patient prognosis and treatment outcome. Despite many important advances in therapy, resistance to therapy represents a difficult challenge in HNSCC patients. Tumor progression, metastasis, and response to therapy are all influenced by the complex ecosystem represented by the tumor microenvironment and by the interactions between cellular and non-cellular components of this system. Therefore, the tumor microenvironment, in the light of recent data, is not an innocent bystander. In the last few years, there has been a sustained effort to characterize the tumor microenvironment, to identify targets of response and identify other mechanisms of tumor-specific immune responses, or to discover other biomarkers of response. There is an urgent need to understand how to properly select patients, the therapy sequence, and how to use feasible biomarkers that can help to identify the patient who may obtain the most benefit from available therapies.

Cervicovaginal Microbiome Factors in Clearance of Human Papillomavirus Infection

Persistent high-risk human papillomavirus (hrHPV) infection is the highest risk to cervical cancer which is the fourth most common cancer in women worldwide. A growing body of literatures demonstrate the role of cervicovaginal microbiome (CVM) in hrHPV susceptibility and clearance, suggesting the promise of CVM-targeted interventions in protecting against or eliminating HPV infection. Nevertheless, the CVM-HPV-host interactions are largely unknown. In this review, we summarize imbalanced CVM in HPV-positive women, with or without cervical diseases, and the progress of exploring CVM resources in HPV clearance. In addition, microbe- and host-microbe interactions in HPV infection and elimination are reviewed to understand the role of CVM in remission of HPV infection. Lastly, the feasibility of CVM-modulated and -derived products in promoting HPV clearance is discussed. Information in this article will provide valuable reference for researchers interested in cervical cancer prevention and therapy.

Pathogenic Role of Immune Evasion and Integration of Human Papillomavirus in Oropharyngeal Cancer

The incidence of oropharyngeal cancer (OPC) is increasing remarkably among all head and neck cancers, mainly due to its association with the human papillomavirus (HPV). Most HPVs are eliminated by the host’s immune system; however, because HPV has developed an effective immune evasion mechanism to complete its replication cycle, a small number of HPVs are not eliminated, leading to persistent infection. Moreover, during the oncogenic process, the extrachromosomal HPV genome often becomes integrated into the host genome. Integration involves the induction and high expression of E6 and E7, leading to cell cycle activation and increased genomic instability in the host. Therefore, integration is an important event in oncogenesis, although the associated mechanism remains unclear, especially in HPV-OPC. In this review, we summarize the current knowledge on HPV-mediated carcinogenesis, with special emphasis on immune evasion and integration mechanisms, which are crucial for oncogenesis.

Immuno-Oncological Biomarkers for Squamous Cell Cancer of the Head and Neck: Current State of the Art and Future Perspectives

The era of immune checkpoint inhibitors has altered the therapeutic landscape in squamous cell cancer of the head and neck (SCCHN). Our knowledge about the tumor microenvironment has fueled the research in SCCHN, leading to several well-known and less-known prognostic and predictive biomarkers. The clinical staging, p16/HPV status, and PD-L1 expression are currently the main tools for assessing the patients' diagnosis and prognosis. However, several novel biomarkers have been thoroughly investigated, some reaching actual significant clinical contributions. The untangling of the immune infiltrate with the subtyping of tissue-associated tumor infiltrating lymphocytes, tumor-associated macrophages, and circulating blood-based biomarkers are an interesting avenue to be further explored and prospectively assessed. Although PD-L1 expression remains the most important response predictor for immune checkpoint inhibitors, several flaws impede proper assessment such as technical issues, different scoring protocol, and intra-, inter-, and temporal heterogeneity. In addition, the construction of an immune-related gene panel has been proposed as a prognostic and predictive stratification but lacks consensus. Recently, the role of microbioma have also been explored regarding its systemic and antitumor immunity. This review gives a comprehensive overview of the aforementioned topics in SCCHN. To this end, the integration of these clinically advantageous biomarkers via construction of an immunogram or nomogram could be an invaluable tool for SCCHN in future prospects.

Novel Concepts: Langerhans Cells in the Tumour Microenvironment

Langerhans cells (LCs) are immune cells that reside in the stratified epithelium of the skin and mucosal membranes. They play a range of roles in the skin, including antigen presentation and maintenance of peripheral tolerance. Reports of LC numbers have been variable in different cancer types, with the majority of studies indicating a reduction in their number. Changes in the cytokine profile and other secreted molecules, downregulation of surface molecules on cells and hypoxia all contribute to the regulation of LCs in the tumour microenvironment. Functionally, LCs have been reported to regulate immunity and carcinogenesis in different cancer types. An improved understanding of the function and biology of LCs in tumours is essential knowledge that underpins the development of new cancer immunotherapies.

Tumor microenvironment: an evil nexus promoting aggressive head and neck squamous cell carcinoma and avenue for targeted therapy

Head and neck squamous cell carcinoma (HNSCC) is a very aggressive disease with a poor prognosis for advanced-stage tumors. Recent clinical, genomic, and cellular studies have revealed the highly heterogeneous and immunosuppressive nature of HNSCC. Despite significant advances in multimodal therapeutic interventions, failure to cure and recurrence are common and account for most deaths. It is becoming increasingly apparent that tumor microenvironment (TME) plays a critical role in HNSCC tumorigenesis, promotes the evolution of aggressive tumors and resistance to therapy, and thereby adversely affects the prognosis. A complete understanding of the TME factors, together with the highly complex tumor-stromal interactions, can lead to new therapeutic interventions in HNSCC. Interestingly, different molecular and immune landscapes between HPV^+ve and HPV^-ve (human papillomavirus) HNSCC tumors offer new opportunities for developing individualized, targeted chemoimmunotherapy (CIT) regimen. This review highlights the current understanding of the complexity between HPV^+ve and HPV^-ve HNSCC TME and various tumor-stromal cross-talk modulating processes, including epithelial-mesenchymal transition (EMT), anoikis resistance, angiogenesis, immune surveillance, metastatic niche, therapeutic resistance, and development of an aggressive tumor phenotype. Furthermore, we summarize the recent developments and the rationale behind CIT strategies and their clinical applications in HPV^+ve and HPV^-ve HNSCC.

Immunohistochemical evaluation of Langerhans cells in oral lichen planus and oral lichenoid lesions

OBJECTIVE

the aim of this study was to evaluate the density of Langerhans cells in oral lichen planus (OLP) and oral lichenoid lesions (OLL).

DESIGN

14 cases of OLP, 15 cases of OLL and 14 cases of oral inflammatory fibrous hyperplasia (OIFH), were selected for immunohistochemical analysis of CD1a, CD207 and S100 expression. The OIFH group was subdivided according to the presence (OIFHL n = 14) or absence (OIFHNL n = 14) of lichenoid inflammatory infiltrate. Positive cells were counted in intraepithelial and subepithelial areas. Results were analyzed by multivariate comparative analysis, correlation analysis, linear regression models and Student's T-test.

RESULTS

A significantly higher amount of CD207+ cells in OLL vs OLP was observed (p = 0.015). The prevailing reticular pattern observed was CD207^high for OLP (p = 0.0329). A statistically significant difference in the expression of CD1a and CD207 was observed for intraepithelial vs subepithelial areas (p = 0.024 and p=0.015, for CD1a and CD207, respectively). Significant correlations were also observed between the expression of CD1a + and CD207+ cells in the pathogenesis of OLP and OLL.

CONCLUSION

High levels of CD207+cells in OLP compared with OLL may help explain the differences in the immunopathogenesis of both diseases. Additionally, CD1a + and CD207+ cells appear to be more essential to immunopathogenesis of OLL than to the pathogenesis of OLP.

Dendritic cells in the tumor microenvironment: prognostic and theranostic impact

Among all immune cells, dendritic cells (DC) are the most potent APCs in the immune system and are central players of the adaptive immune response. There are phenotypically and functionally distinct DC populations derived from blood and lymphoid organ including plasmacytoid DC (pDC), conventional DC (cDC1 and cDC2) and monocyte-derived DC (moDC). The interaction between these different DCs and tumors is a dynamic process where DC-mediated cross-priming of tumor specific T cells is critical in initiating and sustaining anti-tumor immunity. Their presence within the tumor tends to induce T cell responses and to reduce cancer progression and is associated with improved patient survival. This review will focus on the distinct tumor-associated DCs (TADC) subsets in the tumor microenvironment (TME), their roles in tumor immunology and their prognostic and/or predictive impact in human cancers. The development of therapeutic immunity strategies targeting TADC is promising to enhance their immune-stimulatory capacity in cancers and improve the efficacy of current immunotherapies including immune checkpoint inhibitor (ICI) blockade and DC-based therapies.

Immunological Network in Head and Neck Squamous Cell Carcinoma-A Prognostic Tool Beyond HPV Status

Head and neck squamous cell carcinoma (HNSCC) is a highly heterogeneous disease that affects more than 800,000 patients worldwide each year. The variability of HNSCC is associated with differences in the carcinogenesis processes that are caused by two major etiological agents, namely, alcohol/tobacco, and human papillomavirus (HPV). Compared to non-virally induced carcinomas, the oropharyngeal tumors associated with HPV infection show markedly better clinical outcomes and are characterized by an immunologically “hot” landscape with high levels of tumor-infiltrating lymphocytes. However, the standard of care remains the same for both HPV-positive and HPV-negative HNSCC. Surprisingly, treatment de-escalation trials have not shown any clinical benefit in patients with HPV-positive tumors to date, most likely due to insufficient patient stratification. The in-depth analysis of the immune response, which places an emphasis on tumor-infiltrating immune cells, is a widely accepted prognostic tool that might significantly improve both the stratification of HNSCC patients in de-escalation trials and the development of novel immunotherapeutic approaches.

Niche rather than origin dysregulates mucosal Langerhans cells development in aged mice

Unlike epidermal Langerhans cells (LCs) that originate from embryonic precursors and are self-renewed locally, mucosal LCs arise and are replaced by circulating bone marrow (BM) precursors throughout life. While the unique lifecycle of epidermal LCs is associated with an age-dependent decrease in their numbers, whether and how aging has an impact on mucosal LCs remains unclear. Focusing on gingival LCs we found that mucosal LCs are reduced with age but exhibit altered morphology with that observed in aged epidermal LCs. The reduction of gingival but not epidermal LCs in aged mice was microbiota-dependent; nevertheless, the impact of the microbiota on gingival LCs was indirect. We next compared the ability of young and aged BM precursors to differentiate to mucosal LCs. Mixed BM chimeras, as well as differentiation cultures, demonstrated that aged BM has intact if not superior capacity to differentiate into LCs than young BM. This was in line with the higher percentages of mucosal LC precursors, pre-DCs, and monocytes, detected in aged BM. These findings suggest that while aging is associated with reduced LC numbers, the niche rather than the origin controls this process in mucosal barriers.

The Immune Microenvironment in Head and Neck Squamous Cell Carcinoma: on Subsets and Subsites

PURPOSE

To understand why some patients respond to immunotherapy but many do not, a clear picture of the tumor microenvironment (TME) of head and neck squamous cell carcinoma (HNSCC) is key. Here we review the current understanding on the immune composition per HNSCC subsite, the importance of the tumor's etiology and the prognostic power of specific immune cells.

RECENT FINDINGS

Large cohort data are mostly based on deconvolution of transcriptional databases. Studies focusing on infiltrate localization often entail small cohorts, a mixture of HNSCC subsites, or focus on a single immune marker rather than the interaction between cells within the TME. Conclusions on the prognostic impact of specific immune cells in HNSCC are hampered by the use of heterogeneous or small cohorts. To move forward, the field should focus on deciphering the immune composition per HNSCC subsite, in powered cohorts and considering the molecular diversity in this disease.

Different methods of cell quantification can lead to different results: a comparison of digital methods using a pilot study of dendritic cells in HIV-positive patients

BACKGROUND

Although new digital pathology tools have improved the positive cell quantification, there is a heterogeneity of the quantification methods in the literature. The aim of this study was to evaluate and propose a novel dendritic cells quantification method in squamous cell carcinoma comparing it with a conventional quantification method.

MATERIAL AND METHODS

Twenty-six squamous cell carcinomas HIV-positive cases affecting the oropharynx, lips and oral cavity were selected. Immunohistochemistry for CD1a, CD83, and CD207 was performed. The immunohistochemical stains were evaluated by automated examination using a positive pixel count algorithm. A conventional quantification method (unspecific area method; UA) and a novel method (specific area method; SA) were performed obtaining the corresponding density of positive dendritic cells for the intratumoral and peritumoral regions. The Mann-Whitney U test was used to verify the influence of the quantification methods on the positive cell counting according to the evaluated regions. Data were subjected to the ANOVA and Student's t-test to verify the influence of the tumour location, stage, histological grade, and amount of inflammation on the dendritic cells density counting.

RESULTS

The cell quantification method affected the dendritic cells counting independently of the evaluated region (P-value <0.05). Significant differences between methods were also observed according to the tumour features evaluations.

CONCLUSIONS

The positive cell quantification method influences the dendritic cells density results. Unlike the conventional method (UA method), the novel SA method avoids non-target areas included in the hotspots improving the reliability and reproducibility of the density cell quantification.

HPV Involvement in the Tumor Microenvironment and Immune Treatment in Head and Neck Squamous Cell Carcinomas

Head and neck squamous cell carcinomas (HNSCC) are one of the most prevalent cancers worldwide. Active human papillomavirus (HPV) infection has been identified as an important additional risk factor and seems to be associated with a better prognosis in non-drinker and non-smoker young patients with oropharyngeal SCC. The better response of the immune system against the HPV-induced HNSCC is suspected as a potential explanation for the better prognosis of young patients. To further assess this hypothesis, our review aims to shed light the current knowledge about the impact of HPV infection on the immune response in the context of HNSCC, focusing on the innate immune system, particularly highlighting the role of macrophages, Langerhans and myeloid cells, and on the adaptative immune system, pointing out the involvement of T regulatory, T CD8 and T CD4 lymphocytes. In addition, we also review the preventive (HPV vaccines) and therapeutic (checkpoint inhibitors) strategies against HPV-related HNSCC, stressing the use of anti-CTLA4, PD-L1, PD-L2 antibodies alone and in combination with other agents able to modulate immune responses.

Distribution of Dendritic Cells in AIDS-Associated Oral Kaposi's Sarcoma

The aim of this study was to determine if the distribution of Langerhans cells (LC) and interstitial dendritic cells (IDC) is altered in AIDS-associated oral Kaposi's sarcoma when compared to HIV-negative highly vascular oral lesions. Fifty-one cases of AIDS-associated oral Kaposi's sarcoma and 20 of highly vascular oral lesions were retrospectively retrieved. All cases of Kaposi's sarcoma were confirmed with immunoreactions against CD34 and HHV-8. Clinical data regarding sex, age and lesions location were obtained from pathology reports. Immunohistochemistry against CD207 (immature dendritic cells) and CD83 (mature dendritic cells) were done. LC were in the epithelium and IDC in the stroma. CD207+ cells predominated in the epithelium of the lesions, whereas CD83+ cells predominated in their stromal compartment. Kaposi's sarcoma had a lower CD207+ immature LC count (p=0.02) and an increased CD207+ IDC than highly vascular oral lesions (p<0.001). Moreover, Kaposi's sarcoma also showed an increased number of mature CD83+ IDC than highly vascular oral lesions (p<0.001). There were significant alterations in the distribution of LC and IDC in AIDS-associated Kaposi's sarcoma when compared to HIV-negative vascular oral lesions, suggesting that changes in their concentrations may play a role in the pathogenesis of Kaposi's sarcoma.

Impact of HPV Infection on the Immune System in Oropharyngeal and Non-Oropharyngeal Squamous Cell Carcinoma: A Systematic Review

Objectives: To review the current knowledge regarding the involvement of human papilloma virus (HPV) infection and the immune system in the development of head and neck squamous cell carcinoma (HNSCC). Methods: An electronic literature search was conducted to identify articles published between 1990 and 2019 pertaining to tumor-infiltrating immune cells (TICs) in HNSCC using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Issues of clinical relevance, including tumor location, the number of tumor samples, the inclusion of additional specimens (dysplastic or normal mucosa), tumor size, methods used for HPV detection, relationship between antigen expression and patient characteristics (age, gender, smoking, alcohol consumption, etc.), and prognostic data (overall survival (OS) and recurrence-free survival (RFS)) were assessed by four blinded investigators. Results: The search identified 335 relevant studies, of which 41 met the inclusion criteria. Of these, 7 studies focused on the peripheral blood immune cell concentration in patients with HNSCC according to HPV status, and 36 studies investigated TICs in the intraepithelial and/or stromal compartment(s) according to HPV status. The immune cells studied were CD8+ T cells (N = 19), CD4+ T cells (N = 7), regulatory T cells (Tregs, N = 15), macrophages (N = 13), myeloid-derived suppressor cells (MDSCs, N = 4), and Langerhans cells (LCs, N = 2). Conclusions: Irrespective of tumor location, CD8+ and CD4+ T cells appear to play a key role in the development of HPV−related HNSCC, and their infiltration is likely associated with a significant impact on OS and RFS. To date, the roles and prognostic value of Tregs, macrophages, DCs and MDSCs remain unclear.

Papillomavirus Immune Evasion Strategies Target the Infected Cell and the Local Immune System

Persistent infection with human papillomavirus (HPV) initiates ~5% of all human cancers, and particularly cervical and oropharyngeal cancers. HPV vaccines prevent HPV infection, but do not eliminate existing HPV infections. Papillomaviruses induce hyperproliferation of epithelial cells. In this review we discuss how hyperproliferation renders epithelial cells less sensitive to immune attack, and impacts upon the efficiency of the local immune system. These observations have significance for the design of therapeutic HPV cancer immunotherapies.

Human Tumor-Infiltrating Dendritic Cells: From in Situ Visualization to High-Dimensional Analyses

The interaction between tumor cells and the immune system is considered to be a dynamic process. Dendritic cells (DCs) play a pivotal role in anti-tumor immunity owing to their outstanding T cell activation ability. Their functions and activities are broad ranged, triggering different mechanisms and responses to the DC subset. Several studies identified in situ human tumor-infiltrating DCs by immunostaining using a limited number of markers. However, considering the heterogeneity of DC subsets, the identification of each subtype present in the immune infiltrate is essential. To achieve this, studies initially relied on flow cytometry analyses to provide a precise characterization of tumor-associated DC subsets based on a combination of multiple markers. The concomitant development of advanced technologies, such as mass cytometry or complete transcriptome sequencing of a cell population or at a single cell level, has provided further details on previously identified populations, has unveiled previously unknown populations, and has finally led to the standardization of the DCs classification across tissues and species. Here, we review the evolution of tumor-associated DC description, from in situ visualization to their characterization with high-dimensional technologies, and the clinical use of these findings specifically focusing on the prognostic impact of DCs in cancers.

Local inflammatory reaction to benign, pre-malignant and malignant glottic lesions: A matched case-control study

OBJECTIVES

To study the inflammatory infiltrates associated with the different stages of laryngeal carcinogenesis.

DESIGN

Observational, matched case-control study of histopathologic specimens.

SETTING

An academic referral centre.

PARTICIPANTS

A total of 45 patients who underwent removal of glottic lesions between 2008 and 2015. Patients were enrolled and categorised into three matched groups according to lesions' histopathologic diagnoses, 15 patients in each group: benign, pre-malignant and squamous cell carcinoma (SCC). Matching was based on age, gender and pack-years.

MAIN OUTCOME MEASURES

Immunohistochemistry staining using monoclonal antibodies against CD4, CD8, CD68, CD20 and S100 representing T-helper cells, cytotoxic T cells, macrophages, B cells and dendritic cells, respectively. Cell counts and distributions were measured and compared between groups. Correlations between the different cells were examined.

RESULTS

The predominant cell type was CD8+, followed by CD68+ and CD4+. All inflammatory cells increased significantly in number in SCC (P-value < 0.001), with no significant difference between benign and pre-malignant groups. Strong correlations between the different cells were demonstrated only in the malignant group. S100+ cells correlated with both T-cell subsets, CD4+ (rho = 0.769, P-value = 0.001) and CD8+ (rho = 0.697, P-value = 0.0004). Infiltrates exhibited more extensive distribution in SCC compared to pre-malignant and benign; CD8+ and CD68+ cells were demonstrated in both intraepithelial and stromal regions in 93% of SCC lesions (P-value = 0.0001).

CONCLUSIONS

Laryngeal carcinoma demonstrates a unique pattern of inflammatory infiltrates, with significant changes in cell counts and distribution. Leucocyte infiltrates increased significantly in the transition from laryngeal pre-malignant lesion to malignancy while no significant differences were seen between benign and pre-malignant lesions.

The Double-Edged Sword-How Human Papillomaviruses Interact With Immunity in Head and Neck Cancer

Patients with human papilloma virus (HPV)-associated head and neck squamous cell carcinoma (HNSCC) have remarkably better prognosis, which differs from HPV-negative oropharyngeal squamous cell carcinoma (OPSCC) with respect to clinical, genomic, molecular, and immunological aspects, especially having the characteristics of high levels of immune cell infiltration and high degrees of immunosuppression. This review will summarize immune evasion mechanisms in HPV-positive HNSCC, analyze the host various immune responses to HPV and abundant numbers of infiltrating immune cell, and discuss the differences between HPV-positive HNSCC with cervical cancer. A deeper understanding of the immune landscape will help new concepts to emerge in immune-checkpoint oncology, which might be a valuable add-on to established concepts.

Infiltration of FoxP3+ Regulatory T Cells is a Strong and Independent Prognostic Factor in Head and Neck Squamous Cell Carcinoma

Head and Neck Squamous Cell Carcinomas (HNSCC) are characterized by a large heterogeneity in terms of the location and risk factors. For a few years now, immunotherapy seems to be a promising approach in the treatment of these cancers, but a better understanding of the immune context could allow to offer a personalized treatment and thus probably increase the survival of HNSCC patients. In this context, we evaluated the infiltration of FoxP3+ Tregs on 205 human formalin-fixed paraffin-embedded HNSCC and we assessed its prognostic value compared to other potential prognostic factors, including HPV infection. First, we found a positive correlation of FoxP3+ Treg infiltration between the intra-tumoral (IT) and the stromal (ST) compartments of the tumors (p < 0.0001). A high infiltration of these cells in both compartments was associated with longer recurrence-free (ST, RFS, p = 0.007; IT, RFS, p = 0.019) and overall survivals (ST, OS, p = 0.002; ST, OS, p = 0.002) of HNSCC patients. Early tumor stage (OS, p = 0.002) and differentiated tumors (RFS, p = 0.022; OS, p = 0.043) were also associated with favorable prognoses. Multivariate analysis revealed that FoxP3+ Treg stromal infiltration, tumor stage and histological grade independently influenced patient prognosis. In conclusion, the combination of these three markers seem to be an interesting prognostic signature for HNSCC.

Involvement of HPV Infection in the Release of Macrophage Migration Inhibitory Factor in Head and Neck Squamous Cell Carcinoma

Human papilloma virus (HPV) infection has been well-established as a risk factor in head and neck squamous cell carcinoma (HNSCC). The carcinogenic effect of HPV is mainly due to the E6 and E7 oncoproteins, which inhibit the functions of p53 and pRB, respectively. These oncoproteins could also play a role in the Warburg effect, thus favoring tumor immune escape. Here, we demonstrated that the pro-inflammatory cytokine macrophage migration inhibitory factor (MIF) is expressed at higher levels in HPV-negative patients than in HPV-positive patients. However, the secretion of MIF is higher in HPV-positive human HNSCC cell lines, than in HPV-negative cell lines. In-HPV positive cells, the half inhibitory concentration (IC50) of MIF inhibitor (4-iodo-6-phenylpyrimidine (4-IPP)) is higher than that in HPV-negative cells. This result was confirmed in vitro and in vivo by the use of murine SCCVII cell lines expressing either E6 or E7, or both E6 and E7. Finally, to examine the mechanism of MIF secretion, we conducted proton nuclear magnetic resonance (¹H-NMR) experiments, and observed that lactate production is increased in both the intracellular and conditioned media of HPV-positive cells. In conclusion, our data suggest that the stimulation of enzymes participating in the Warburg effect by E6 and E7 oncoproteins increases lactate production and hypoxia inducible factor 1α (HIF-1α) expression, and finally induces MIF secretion.

Activities of stromal and immune cells in HPV-related cancers

The immune system is composed of immune as well as non-immune cells. As this system is a well-established component of human papillomavirus- (HPV)-related carcinogenesis, high risk human papillomavirus (hrHPV) prevents its routes and mechanisms in order to cause the persistence of infection. Among these mechanisms are those originated from stromal cells, which include the cancer-associated fibroblasts (CAFs), the myeloid-derived suppressor cells (MDSCs) and the host infected cells themselves, i.e. the keratinocytes. These types of cells play central role since they modulate immune cells activities to create a prosperous milieu for cancer development, and the knowledge how such interactions occur are essential for prognostic assessment and development of preventive and therapeutic approaches. Nevertheless, the precise mechanisms are not completely understood, and this lack of knowledge precluded the development of entirely efficient immunotherapeutic strategies for HPV-associated tumors. As a result, an intense work for attaining how host immune response works, and developing of effective therapies has been applied in the last decade. Based on this, this review aims to discuss the major mechanisms of immune and non-immune cells modulated by hrHPV and the potential and existing immunotherapies involving such mechanisms in HPV-related cancers. It is noticed that the combination of immunotherapies has been demonstrated to be essential for obtaining better results, especially because the possibility of increasing the modulating capacity of the HPV-tumor microenvironment has been shown to be central in strengthening the host immune system.

High stromal Foxp3-positive T cell number combined to tumor stage improved prognosis in head and neck squamous cell carcinoma

OBJECTIVES

Head and neck squamous cell carcinomas (HNSCC), one of the most frequent cancers in the world, are largely infiltrated by inflammatory immune cells. Our aim was to evaluate the number of Foxp3+ T cells in HNSCC, reporting its prognostic power in comparison to other risk factors.

MATERIAL AND METHODS

Our clinical series was composed of 21 tumor-free peri-tumoral epithelia, 49 low grade dysplasia, 43 high grade dysplasia and 110 carcinoma samples including some cases with HPV infection. In vivo experiments were conducted on 80 C3H/HeN mice which were orthotopically injected with SCCVII CT, E7, E6 and E6/E7 cell lines.

RESULTS

Foxp3+ T cell infiltration increased with tumor progression from normal epithelia, dysplasia to carcinoma and the increase is more important in HPV+ patients than in negative ones. Animal experiments revealed that E7 oncoprotein expression was significantly associated with an increase in Foxp3+ T cell recruitment in tumor, a delay in tumor onset and improved animal survival. Univariate Cox regression analyses demonstrated that high Foxp3+ T cell number in stromal compartment is associated with longer patient recurrence-free and overall survivals. Foxp3+ T cell number improved the prognostic value of tumor stage. Multivariate analyses reported that stromal Foxp3+ T cell number is a strong prognostic factor independent of classical risk factors such as tobacco, alcohol, and HPV status.

CONCLUSION

Foxp3+ T cell number is a significant prognostic factor for HNSCC, improving the tumor stage, and that viral E7 may play a role in the Foxp3+ T cell infiltration to the tumor.

A decreased peritumoral CD1a+ cell number predicts a worse prognosis in oral squamous cell carcinoma

AIMS

Dendritic cells (DCs) are known to play a central role in the regulation of both innate and adaptive immunological responses, including antitumour immunity. The aim of this study was to evaluate the prognostic impact of intratumoral and peritumoral DCs in oral squamous cell carcinoma (OSCC) affecting the tongue and floor of the mouth.

METHODS AND RESULTS

Immunohistochemistry for CD1a and CD83 was performed in 53 patients with OSCC in the tongue and floor of the mouth. The markers were evaluated by automated examination in intratumoral and peritumoral compartments, and the results were expressed as density of cells/mm² . Correlations between these data and clinicopathological and survival outcomes were investigated. Depletion of peritumoral CD1a+ cells was associated with lymph node metastasis (P = 0.05), whereas depletion of peritumoral CD83+ cells was correlated with smoking history (P = 0.04), lymph node metastasis (P = 0.015), and extracapsular spread of lymph nodes (P = 0.018). Peritumoral CD1a+ was correlated with recurrence (P = 0.007) and overall survival (P = 0.03). The results of the survival analysis with the Cox proportional hazard model showed that depletion of peritumoral CD1a+ cells is an independent factor associated with overall survival and disease-free survival.

CONCLUSION

Our results suggest that depletion of peritumoral CD1a+ cells is a strong independent prognostic factor, predicting a higher recurrence rates and worse survival outcomes.

High infiltration of CD68+ macrophages is associated with poor prognoses of head and neck squamous cell carcinoma patients and is influenced by human papillomavirus

Incidence of human papillomavirus (HPV)-related head and neck squamous cell carcinomas (HNSCCs) has increased over the last few decades. The reaction of the host immune system to these tumors remains biologically complex. Here, we investigated CD68+ macrophage numbers, reporting the prognostic value in comparison to other risk factors. We also examined CD68+ macrophage infiltration during disease progression regarding the impact of HPV infection, and we studied the role of HPV16-E6/E7 oncoproteins in CD68+ macrophage recruitment. CD68+ macrophage numbers were evaluated in 10 cases of tumor-free peri-tumoral epithelia, 43 cases of low-grade dysplasia, 45 cases of high-grade dysplasia and 110 cases of carcinoma. Our in vivo model was developed in 80 C3H/HeN mice orthotopically injected with HPV16-E6, -E7 or -E6/E7-transfected SCC-VII cell lines. High CD68+ macrophage numbers in the intra-tumoral compartment were associated with shorter patient survival (recurrence-free survival: p = 0.001; overall survival: p = 0.01). Multivariate analyses reported that CD68+ macrophage infiltration and tumor stage were strong and independent prognostic factors of HNSCC. CD68+ macrophage numbers increased during HNSCC progression both in intra-epithelial (p < 0.001) and stromal compartments (p < 0.001). A higher density of CD68+ macrophages was observed in advanced stages (p = 0.004). Patients with transcriptionally active HPV infections had higher CD68+ macrophage density than did HPV-negative patients (p = 0.003). CD68+ macrophage infiltration was higher in HPV-E7+ and −E6/E7+ mouse tumors than in -E6+ tumors (p = 0.029 and p < 0.001). In conclusion, the extent of CD68+ macrophage infiltration is a significant prognostic factor for HNSCC patients. The recruitment of macrophages increases during disease progression and is influenced by the HPV virus.

Modulation of antigen presenting cell functions during chronic HPV infection

High-risk human papillomaviruses (HR-HPV) infect basal keratinocytes, where in some individuals they evade host immune responses and persist. Persistent HR-HPV infection of the cervix causes precancerous neoplasia that can eventuate in cervical cancer. Dendritic cells (DCs) are efficient in priming/cross-priming antigen-specific T cells and generating antiviral and antitumor cytotoxic CD8+ T cells. However, HR-HPV have adopted various immunosuppressive strategies, with modulation of DC function crucial to escape from the host adaptive immune response. HPV E6 and E7 oncoproteins alter recruitment and localization of epidermal DCs, while soluble regulatory factors derived from HPV-induced hyperplastic epithelium change DC development and influence initiation of specific cellular immune responses. This review focuses on current evidence for HR-HPV manipulation of antigen presentation in dendritic cells and escape from host immunity.

Intratumoral HPV16-Specific T Cells Constitute a Type I-Oriented Tumor Microenvironment to Improve Survival in HPV16-Driven Oropharyngeal Cancer

Purpose: Human papillomavirus (HPV)-associated oropharyngeal squamous cell cancer (OPSCC) has a much better prognosis than HPV-negative OPSCC, and this is linked to dense tumor immune infiltration. As the viral antigens may trigger potent immunity, we studied the relationship between the presence of intratumoral HPV-specific T-cell responses, the immune contexture in the tumor microenvironment, and clinical outcome.Experimental Design: To this purpose, an in-depth analysis of tumor-infiltrating immune cells in a prospective cohort of 97 patients with HPV16-positive and HPV16-negative OPSCC was performed using functional T-cell assays, mass cytometry (CyTOF), flow cytometry, and fluorescent immunostaining of tumor tissues. Key findings were validated in a cohort of 75 patients with HPV16-positive OPSCC present in the publicly available The Cancer Genome Atlas database.Results: In 64% of the HPV16-positive tumors, type I HPV16-specific T cells were present. Their presence was not only strongly related to a better overall survival, a smaller tumor size, and less lymph node metastases but also to a type I-oriented tumor microenvironment, including high numbers of activated CD161⁺ T cells, CD103⁺ tissue-resident T cells, dendritic cells (DC), and DC-like macrophages.Conclusions: The viral antigens trigger a tumor-specific T-cell response that shapes a favorable immune contexture for the response to standard therapy. Hence, reinforcement of HPV16-specific T-cell reactivity is expected to boost this process. Clin Cancer Res; 24(3); 634-47. ©2017 AACRSee related commentary by Laban and Hoffmann, p. 505.

Langerhans cell counts in oral epithelial dysplasia and their correlation to clinicopathological parameters

BACKGROUND/PURPOSE

Langerhans cells (LCs) are antigen presenting cells. This study assessed the LC counts in oral epithelial dysplasia (OED) and their correlation to clinicopathological parameters.

METHODS

This study examined the LC counts in the epithelia and subepithelial connective tissues of 58 patients with OED (21 mild, 18 moderate, and 19 severe OED lesions) and 10 specimens of normal oral mucosa (NOM) by anti-S-100 protein immunostaining.

RESULTS

We found that the mean LC counts in the epithelia or subepithelial connective tissues increased significantly from NOM samples through mild and moderate OED to severe OED samples. In addition, a significant correlation was found between higher mean LC counts in the dysplastic epithelia of OED samples and OED lesions with thicker epithelial layers (p<0.001) or wider inflammatory zones (p<0.001), and between higher mean LC counts in the subepithelial connective tissues of OED samples and OED lesions with wider inflammatory zones (p<0.001). Moreover, the nine OED lesions with malignant transformation had a significantly lower mean LC count than the 49 OED lesions without malignant transformation.

CONCLUSION

The significant and gradual elevation in LC count from NOM through mild and moderate OED to severe OED lesions suggests an upregulation of immunosurveillance ability in OED patients during the early oral carcinogenesis process. A low LC count in OED lesions may suggest the partial loss of immunosurveillance ability against dysplastic cells; this in turn favors the malignant transformation of an OED lesion into oral cancer.