Rationale: Immunosuppressive tumor microenvironment (iTME) plays an important role in carcinogenesis, and some macrophage subsets are associated with iTME generation. However, the sub-population characterization of macrophages in oral carcinogenesis remains largely unclear. Here, we investigated the immunosuppressive status with focus on function of a macrophage subset that expressed indoleamine 2,3 dioxygenase 1 (Macro-IDO1) in oral carcinogenesis. Methods: We built a single cell transcriptome atlas from 3 patients simultaneously containing oral squamous cell carcinoma (OSCC), precancerous oral leukoplakia (preca-OLK) and paracancerous tissue (PCA). Through single-cell RNA sequencing and further validation using multicolor immunofluorescence staining and the in vitro/in vivo experiments, the immunosuppressive cell profiles were built and the role of a macrophage subset that expressed indoleamine 2,3 dioxygenase 1 (Macro-IDO1) in the malignant transformation of oral leukoplakia was evaluated. Results: The iTME formed at preca-OLK stage, as evidenced by increased exhausted T cells, Tregs and some special subsets of macrophages and fibroblasts. Macro-IDO1 was predominantly enriched in preca-OLK and OSCC, distributed near exhausted T cells and possessed tumor associated macrophage transformation potentials. Functional analysis revealed the established immunosuppressive role of Macro-IDO1 in preca-OLK and OSCC: enriching the immunosuppression related genes; having an established level of immune checkpoint score; exerting strong immunosuppressive interaction with T cells; positively correlating with the CD8-exhausted. The immunosuppression related gene expression of macrophages also increased in preca-OLK/OSCC compared to PCA. The use of the IDO1 inhibitor reduced 4NQO induced oral carcinogenesis in mice. Mechanistically, IFN-γ-JAK-STAT pathway was associated with IDO1 upregulation in OLK and OSCC. Conclusions: These results highlight that Macro-IDO1-enriched in preca-OLK possesses a strong immunosuppressive role and contributes to oral carcinogenesis, providing a potential target for preventing precancerous legions from transformation into OSCC.

BACKGROUND: The role of microbes in diseases, especially cancer, has garnered significant attention. However, research on the oral microbiota in oral potentially malignant disorders (OPMDs) remains limited. Our study investigates microbial communities in OPMDs.
METHODS: Oral biopsies from19 oral leukoplakia (OLK) patients, 19 proliferative verrucous leukoplakia (PVL) patients, 19 oral lichen planus (OLP) patients, and 19 oral lichenoid lesions (OLL) patients were obtained. 15 SCC specimens were also collected from PVL patients. Healthy individuals served as controls, and DNA was extracted from their paraffin-embedded tissues. 2bRAD-M sequencing generated taxonomic profiles. Alpha and beta diversity analyses, along with Linear Discriminant Analysis effect size analysis, were conducted.
RESULTS: Our results showed the microbial richness and diversity were significantly different among groups, with PVL-SCC resembling controls, while OLK exhibited the highest richness. Each disease group displayed unique microbial compositions, with distinct dominant bacterial species. Noteworthy alterations during PVL-SCC progression included a decline in Fusobacterium periodonticum and an elevation in Prevotella oris.
CONCLUSIONS: Different disease groups exhibited distinct dominant bacterial species and microbial compositions. These findings offer promise in elucidating the underlying mechanisms of this disease.

OBJECTIVE: Chemoprevention can be a treatment for potentially malignant lesions (PMLs). We aimed to evaluate whether artemisinin (ART) and cisplatin (CSP) are associated with apoptosis and immunogenic cell death (ICD) in vitro, using oral leukoplakia (OL) and oral squamous cell carcinoma (OSCC) cell lines, and whether these compounds prevent OL progression in vivo.
METHODS: Normal keratinocytes (HaCat), Dysplastic oral cells (DOK), and oral squamous cell carcinoma (SCC-180) cell lines were treated with ART, CSP, and ART + CSP to analyze cytotoxicity, genotoxicity, cell migration, and increased expression of proteins related to apoptosis and ICD. Additionally, 41 mice were induced with OL using 4NQO, treated with ART and CSP, and their tongues were histologically analyzed.
RESULTS: In vitro, CSP and CSP + ART showed dose-dependent cytotoxicity and reduced SCC-180 migration. No treatment was genotoxic, and none induced expression of proteins related to apoptosis and ICD; CSP considerably reduced High-mobility group box-1 (HMGB-1) protein expression in SCC-180. In vivo, there was a delay in OL progression with ART and CSP treatment; however, by the 16th week, only CSP prevented progression to OSCC.
CONCLUSIONS: Expression of proteins related to ICD and apoptosis did not increase with treatments, and CSP was shown to reduce immunogenic pathways in SCC-180, while reducing cell migration. ART did not prevent the malignant progression of OL in vivo; CSP did despite significant adverse effects.

The objective of the present study was to investigate the frequency of oral leukoplakia and oral erythroplakia among young patients from three Brazilian reference centers in Oral and Maxillofacial Pathology. A retrospective study was carried out from 2011 to 2021 on 861 patients diagnosed with oral leukoplakia and oral erythroplakia. Demographic and clinicopathological data were evaluated. Fisher\'s exact test was used to evaluate the association among sex, age, anatomical location, and histopathological diagnosis. A total of 83 (9.64%) cases involved young patients (aged <40 years). Among these, biopsy records were included in 31 (37.34%) cases, all of which received a clinical diagnosis of oral leukoplakia. Seventeen (54.84%) patients were female, mostly in their fourth decade of life (n = 22/70.97%), and their mean age at diagnosis was 32.61(± 5.21) years. Among informed cases, seven (22.58%) patients were smokers. The lateral border of the tongue (n = 9/29.03%) was the most affected site. In 13 (41.94%) cases, oral leukoplakias showed a homogeneous appearance. The mean size of the lesions was 1.47 cm (0.2-3.0 cm) and the mean time of disease progression was 64.37 (± 65.90) months. The histopathological analysis showed that 11 cases (35.48%) exhibited some degree of epithelial dysplasia. Acanthosis and/or hyperkeratosis were observed in 20 cases (64.52%). No significant associations were observed between sex and anatomical location, age and anatomical location, nor between sex and histological diagnosis (p > 0.05). Oral leukoplakia and oral erythroplakia are uncommon diseases in young patients. In this population, oral leukoplakia shows a slight predilection for women aged between 30 and 39 years.

OBJECTIVE: To evaluate the oral health-related quality of life (OHRQoL) of individuals diagnosed with Fanconi anemia (FA).
METHODS: A cross-sectional study was conducted with FA patients from two Brazilian referral centers. Participants underwent a complete dental, periodontal, and oral mucosa examination, as well as assessment of resting salivary flow. The short version of the Oral Health Impact Profile (OHIP-14) questionnaire was administered. Descriptive and bivariate analyses were performed, followed by multivariate analysis to examine the impact of independent variables on OHRQoL.
RESULTS: The study included 20 (57.1%) males and 15 (42.9%) females, with a mean age of 18.9 years. Oral leukoplakia (OL) was found in 18 individuals. The overall OHIP-14 score was 9.9 ± 10.5. Individuals aged ≥ 16 years had higher OHIP-14 scores, indicating worse OHRQoL for physical pain (p = 0.007), psychological discomfort (p = 0.001), physical disability (p = 0.03), psychological disability (p = 0.001), handicap (p = 0.004), and overall score (p = 0.007). Females reported more negative OHRQoL than males for physical pain (p = 0.02), psychological discomfort (p = 0.03), psychological disability (p = 0.009), and overall score (p = 0.02). Individuals with OL had an overall OHIP-14 score 1.83 times higher than those without OL (95% CI: 1.02-3.28; p = 0.04). Lower salivary flow correlated with higher overall OHIP-14 scores (95% CI: 0.14-0.84; p = 0.01).
CONCLUSIONS: This study represents the first attempt to evaluate OHRQoL in individuals with FA. The presence of OL and reduced salivary flow were identified as predictors of a negative impact on OHRQoL. It is imperative to integrate patients\' quality of life in the clinical treatment protocols for the FA population.

This manuscript critically examines the current classification of oral potentially malignant disorders, questioning the practicality and implications of labeling such a large population as precancerous, given that the actual progression to oral cancer is significantly low for most disorders. The paper advocates for a revised classification system that accurately reflects the varying malignancy risks associated with different disorders. It suggests a reassessment of the diagnostic and management approaches to mitigate overdiagnosis and alleviate patient burdens. We propose categorizing diseases with oral malignant potential as follows: Oral Precancerous Diseases, encompassing high-risk lesions and conditions like erythroplakia, non-homogeneous leukoplakia, proliferative leukoplakia, and actinic keratosis; Oral Potentially Premalignant Diseases, covering lesions, conditions, and systemic diseases with distinct oral manifestations harboring a limited or undefined risk of transformation, such as homogeneous leukoplakia, oral submucous fibrosis, oral lichenoid diseases, chronic hyperplastic candidosis, keratosis of known aetiology (smokeless tobacco, khat), palatal lesions in reverse smokers, and dyskeratosis congenita; and Systemic Conditions with Oral Malignant Potential including Fanconi\'s anemia, xeroderma pigmentosum, and chronic immunosuppression (including patients post-bone marrow transplantation), which are associated with an increased risk of oral cancer without preceding precursor lesions. We provide illustrative examples to demonstrate how this framework offers practical guidance for research, policy-making, and clinical practice.

BACKGROUND: The incidence of oral cancer has exhibited a rise within the young population. Considering that oral potentially malignant disorders (OPMDs) can precede the development of oral cancer, it is imperative to conduct studies in this particular younger population. This study aimed to evaluate the frequency and conduct a comparative analysis of the clinical-demographic characteristics of OPMDs in two distinct age groups.
METHODS: A retrospective analysis was conducted with patients diagnosed with leukoplakia, erythroplakia, and leukoerythroplakia between 1965 and 2020. The individuals were categorized into two groups: those aged up to 40 years (Group Younger) and those aged 41 years and above (Group Older).
RESULTS: A total of 640 lesions were subjected to analysis. Among these, patients aged up to 40 years constituted 10.63% of the sample, however, this proportion decreased significantly to 6.9% between 2010 and 2020. A predominant male representation was observed in both groups, with white lesions being the most common in both as well. However, the frequency of red or mixed lesions was significantly higher (p=0.034) in the older group, along with a higher prevalence of dysplastic lesions (26.9% versus 11.8%, p=0.01). Moreover, the older group exhibited a relatively higher percentage of smokers/ex-smokers (78.6%), compared to the younger group (61.5%, p=0.085) and alcohol consumers/ex-consumers (54.9% versus 22.7%, p=0.028). Elderly individuals exhibited an unfavorable progression (p=0.028). However, a logistic regression analysis identified as significant variables associated with malignant transformation, the presence of epithelial dysplasia, and red lesions diagnosed as erythroplakia.
CONCLUSIONS: A declining frequency of OPMDs in young adults was observed over the years, whereas in older adults, these disorders exhibited an unfavorable progression.

BACKGROUND: Radiotherapy (RT) has numerous effects on the oral mucosa, primarily genetic alterations and changes in the microenvironment. The characteristics of oral leukoplakia (OL) may differ between patients who have received previous head and neck cancer (HNC) treatment with radiation therapy and those who have not. Due to a lack of data on this scenario, we aimed to investigate the surgical outcomes of OL by comparing these two patient groups.
METHODS: This retrospective cohort study enrolled a total of 224 OL lesions in 124 patients who underwent carbon dioxide laser (CO2 laser) surgery from July 2002 to Aug 2021. All patients had received previous treatments for HNC, with 59 patients undergoing only surgical approach, 65 patients undergoing RT, and 46 patients undergoing concurrent chemotherapy during RT. The analysis was performed on a per-lesion basis, not a per-capita basis. We investigated the associations of clinicopathological characteristics and treatment outcomes of OL lesions that developed from irradiated or nonirradiated oral mucosa.
RESULTS: The median follow-up time was 5.87 years. Postoperative recurrence of OL occurred in 30 patients. Malignant transformation occurred in 17 patients with the incidence rate 4.19% annually and 13.7% cumulatively. The average time for OL transforming into squamous cell carcinoma was 3.27 ± 3.26 years (median 1.82, range 0.11 - 11.90). In univariate analysis, non-homogeneous morphology (P = 0.042), moderate to high-grade dysplasia (P = 0.041), and nonirradiated oral mucosa (P = 0.0047) were predictors for malignant transformation. However, in the Cox proportional hazard model, only nonirradiated oral mucosa remained an independent prognostic factor related to postoperative malignant transformation of OL (P = 0.031, HR 5.08, CI95 1.16 - 22.25).
CONCLUSIONS: In the population whose OL is strongly aetiologically linked to environmental carcinogens such as betel nut and tobacco, OL lesions that develop on previously irradiated oral mucosa have a lower risk for postoperative malignant transformation compared to those that develop on nonirradiated mucosa. This finding highlights the potential impacts of radiation on OL. Further research is needed to confirm this observation and elucidate the underlying mechanism.

OBJECTIVE: Precancer biomarkers help in early detection and management of oral potentially malignant disorders (OPMDs). Interleukin-1β (IL-1β), a biomarker, is known to be altered in oral submucous fibrosis (OSMF) and oral leukoplakia (OL). Therefore, we evaluated and compared the serum and salivary IL-1β levels in patients with OSMF/oral leukoplakia and in gender- and age-matched healthy individuals.
METHODS: An in vivo, prospective, observational study was conducted on 40 subjects. Subjects were divided into two groups with 20 individuals in each group, that is, Group I: OSMF/oral leukoplakia and Group II: control group. Salivary and serum IL-1β levels were quantitatively estimated using enzyme-linked immunosorbent assay (ELISA). The statistical tests used were unpaired t-test and Chi-square test.
RESULTS: The serum IL-1β levels were significantly (P 0.001) lesser in Group I in comparison to Group II. The salivary IL-1β levels remained insignificant between both the groups. However, in both the groups, the salivary IL-1β levels were significantly higher compared to the serum IL-1β levels.
CONCLUSIONS: We found that the serum IL-1β level can be considered as a prospective biomarker for dysplasia, whereas salivary IL-1β alone needs more elaborated studies to account for its application as a potential biomarker in OPMD.

BACKGROUND: Oral leukoplakia (OLK) is the most common oral potentially malignant disorder (OPMD), which can be malignantly transformed into oral squamous cell carcinoma (OSCC). Peroxiredoxin1(Prx1) has been predicted to bind to Prohibitin2 (PHB2), which confers to affect OLK progression; however, the mechanism of Prx1/PHB2 mediated mitophagy involved in OLK remains unclear.
METHODS: This study aimed to explore the mechanism of the Prx1/PHB2 axis on senescence in OLK through mediating mitophagy. The positive rate of Ki67 and the expression of p21, p16, PHB2, and LC3 in human normal, OLK, and OSCC tissues were detected by immunohistochemical staining. The mitophagy and mitochondrial function changes were then analyzed in Prx1 knockdown and Prx1C52S mutations in dysplastic oral keratinocyte (DOK) cells treated with H2O2. In situ Proximity Ligation Assay combined with co-immunoprecipitation was used to detect the interaction between Prx1 and PHB2.
RESULTS: Clinically, the positive rate of Ki67 progressively increased from normal to OLK, OLK with dysplasia, and OSCC. Higher p21, p16, PHB2, and LC3 expression levels were observed in OLK with dysplasia than in normal and OSCC tissues. In vitro, PHB2 and LC3II expression gradually increased with the degree of DOK cell senescence. Prx1/PHB2 regulated mitophagy and affected senescence in H2O2-induced DOK cells. Furthermore, Prx1C52S mutation specifically reduced interaction between Prx1 and PHB2. Prx1Cys52 is associated with mitochondrial reactive oxygen species (ROS) accumulated and cell cycle arrest.
CONCLUSIONS: Prx1Cys52 functions as a redox sensor that binds to PHB2 and regulates mitophagy in the senescence of OLK, suggesting its potential as a clinical target.