Oral Candida colonization in oral cancer patients and its relationship with traditional risk factors of oral cancer: a matched case-control study

Oral Microbiome and Subsequent Risk of Head and Neck Squamous Cell Cancer

Importance

The oral microbiota may be involved in development of head and neck squamous cell cancer (HNSCC), yet current evidence is largely limited to bacterial 16S amplicon sequencing or small retrospective case-control studies.

Objective

To test whether oral bacterial and fungal microbiomes are associated with subsequent risk of HNSCC development.

Design, Setting, and Participants

Prospective nested case-control study among participants providing oral samples in 3 epidemiological cohorts, the American Cancer Society Cancer Prevention Study II Nutrition Cohort, the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial, and the Southern Community Cohort Study. Two hundred thirty-six patients who prospectively developed HNSCC were identified during a mean (SD) of 5.1 (3.6) years of follow-up. Control participants who remained HNSCC free were selected by 2:1 frequency matching on cohort, age, sex, race and ethnicity, and time since oral sample collection. Data analysis was conducted in 2023.

Exposures

Characterization of the oral bacterial microbiome using whole-genome shotgun sequencing and the oral fungal microbiome using internal transcribed spacer sequencing. Association of bacterial and fungal taxa with HNSCC was assessed by analysis of compositions of microbiomes with bias correction. Association with red and orange oral pathogen complexes was tested by logistic regression. A microbial risk score for HNSCC risk was calculated from risk-associated microbiota.

Main Outcomes and Measures

The primary outcome was HNSCC incidence.

Results

The study included 236 HNSCC case participants with a mean (SD) age of 60.9 (9.5) years and 24.6% women during a mean of 5.1 (3.6) years of follow-up, and 485 matched control participants. Overall microbiome diversity at baseline was not related to subsequent HNSCC risk; however 13 oral bacterial species were found to be differentially associated with development of HNSCC. The species included the newly identified Prevotella salivae, Streptococcus sanguinis, and Leptotrichia species, as well as several species belonging to beta and gamma Proteobacteria. The red/orange periodontal pathogen complex was moderately associated with HNSCC risk (odds ratio, 1.06 per 1 SD; 95% CI, 1.00-1.12). A 1-SD increase in microbial risk score (created based on 22 bacteria) was associated with a 50% increase in HNSCC risk (multivariate odds ratio, 1.50; 95% CI, 1.21-1.85). No fungal taxa associated with HNSCC risk were identified.

Conclusions and Relevance

This case-control study yielded compelling evidence that oral bacteria are a risk factor for HNSCC development. The identified bacteria and bacterial complexes hold promise, along with other risk factors, to identify high-risk individuals for personalized prevention of HNSCC.

Clinical and Biological Perspectives on Noncanonical Esophageal Squamous Cell Carcinoma in Rare Subtypes

Esophageal squamous cell carcinoma (ESCC) remains the most common malignancy of the esophagus worldwide. Environmental and lifestyle exposures such as alcohol and tobacco have been well defined in the pathogenesis of ESCC, acting in concert with cell intrinsic epigenomic, genomic and transcriptomic changes. However, a variety of nonenvironmental etiologies including Fanconi anemia, lichen planus, chronic mucocutaneous candidiasis, esophageal epidermoid metaplasia, epidermolysis bullosa, tylosis, esophageal atresia, and achalasia receive minimal attention despite a high risk of ESCC in these diseases. The goal of this review was to promote clinical recognition and suggest a diagnostic framework for earlier detection of ESCC in patients with these rare diseases. In all the discussed conditions, a change in symptoms should trigger a prompt endoscopic evaluation, and endoscopic surveillance programs with advanced imaging techniques and chromoendoscopy should be considered. Moreover, we leverage the convergence of these diseases on ESCC to identify common mechanisms underlying malignant transformation including aberrant proliferation, mucosal barrier dysfunction, increased inflammation, and genome instability. In this study, we summarize the clinical presentation, pathologic findings, potential screening strategies, and common mechanisms of malignant transformation associated with these rare diseases that drive ESCC.

The modern face of esophageal candidiasis in an oncology center: Correlating clinical manifestations, endoscopic grade, and pathological data in 323 contemporary cancer patients

OBJECTIVES

Clinical presentation and outcomes of esophageal candidiasis (EC) in cancer patients are scarcely studied in the azole era, as is the correlation between clinical, endoscopic, and histopathological EC manifestations.

METHODS

We retrospectively reviewed the risk factors, clinical features, and outcomes of pathology-documented EC cases at MD Anderson Cancer Center. We further assessed associations between presence of symptoms, standardized 4-stage endoscopic grade (Kodsi classification), histopathological data, and fluconazole treatment failure.

RESULTS

Among 323 cancer patients with EC, 89% had solid tumors, most commonly esophageal cancer (29%). Thirty-three percent of EC patients were asymptomatic. The proportion of symptomatic EC patients significantly increased with endoscopic grade (P = 0.005). Among 202 patients receiving oral fluconazole, 27 (13%) had treatment failure. Underlying esophageal disease was the only independent predictor of fluconazole treatment failure (odds ratio: 3.88, P = 0.005). Endoscopic grade correlated significantly with Candida organism burden (Correlation coefficient [ρ] = 0.21, P < 0.01) and neutrophilic inflammation (ρ = 0.18, P < 0.01). Candida invasion of the squamous mucosal layer was associated with treatment failure (P = 0.049).

CONCLUSIONS

EC was predominantly encountered in patients with solid tumors. One-third of EC patients were asymptomatic, challenging traditional symptom-based diagnosis. The development of integrated clinicopathological scoring systems could further guide the therapeutic management of cancer patients with EC.

Worldwide trend in research on Candida albicans and cancer correlations: a comprehensive bibliometric analysis

Objective

Candida albicans (C. albicans), an opportunistic pathogen, is implicated in the carcinogenesis of various cancers, thereby significantly impacting human health. This study conducts an in-depth analysis of the prevailing research dynamics concerning the relationship between C. albicans and cancer over the past decade, offering a comprehensive overview of the knowledge structure and emerging focal points in this field through bibliometric scrutiny.

Methods

A methodical quantitative and visual scrutiny of pertinent literature from the Web of Science Core Collection (WoSCC) spanning the previous decade was carried out employing VOS Viewer and CiteSpace software.

Results

From January 1, 2014, to January 1, 2024, a comprehensive corpus of 1,259 articles was delineated. Prominent research institutions included the Egyptian Knowledge Bank, Cairo University, and King Saud University. The top three prolific countries were the United States, China, and India. Among the authors, Mohamed, Gehad G., Mahmoud, Walaa H., and Netea, Mihai G., emerged as the most prolific, with Pfaller, Ma being distinguished as the most frequently cited author. The journal Molecules published the highest number of articles, while PLoS One had the highest citation count. Nature had the highest impact factor. The research focal points in this field encompassed the interactions between C. albicans and cancer, the correlation with oral cancer, the underlying mechanisms of C. albicans carcinogenic potential, as well as antifungal and anticancer therapies.

Conclusion

This investigation constitutes a pioneering bibliometric analysis elucidating the trends and advancements in research regarding the correlation between C. albicans and cancer. Said analyses uncover the prevailing research focal points and trends, offering insightful guidance for subsequent inquiry in this domain.

Systematic review registration

https://www.webofscience.com/wos/woscc/summary/df33afba-f843-41e8-b932-cb3678eb8243-e92e7316/relevance/1.

The evil companion of OSCC: Candida albicans

OBJECTIVE

Microbial dysbiosis and microbiome-induced inflammation may play a role in the etiopathogenesis of oral squamous cell carcinoma (OSCC). Candida albicans (C. albicans) is the most prevalent opportunistic pathogenic fungus in the oral cavity, and Candida infection is considered as one of its high-risk factors. Although oral microbiota-host interactions are closely associated with the development of OSCC, the interrelationship between fungi and OSCC is poorly understood compared to that between bacteria and viruses.

RESULTS

We accumulated knowledge of the evidence, pathogenic factors, and possible multiple mechanisms by which C. albicans promotes malignant transformation of OSCC, focusing on the induction of epithelial damage, production of carcinogens, and regulation of the tumor microenvironment. In addition, we highlight the latest treatment strategies for Candida infection.

CONCLUSION

This review provides a new perspective on the interrelationship between C. albicans and OSCC and contributes to the establishment of a systematic and reliable clinical treatment system for OSCC patients with C. albicans infection.

Oral Mycobiota: A Narrative Review

Numerous studies have proven the important role of the oral microbiota in health and disease. The dysfunctionality of the oral microbiota, known as dysbiosis, is incriminated in dental caries, periodontal disease, oral infectious diseases, oral cancer, and systemic disease. The lesser-known component of the oral microbiota, the mycobiota, is now assiduously investigated. Recent technological developments have helped foster the identification of new fungal species based on genomic research. Next-generation sequencing has expanded our knowledge about the diversity, architecture, and relationships of oral microorganisms within the oral cavity. The mycobiome structure and relationships with the bacteriome have been studied to identify a mycobiotic signature. This review aimed to emphasize the latest knowledge of the oral mycobiome.

Topical clobetasol treatment for oral lichen planus can cause adrenal insufficiency

OBJECTIVE

Glucocorticoids suppress the hypothalamic-pituitary-adrenal axis, which may lead to glucocorticoid-induced adrenal insufficiency. The study aimed to investigate the prevalence of this state in patients with oral lichen planus treated with topical clobetasol propionate.

METHODS

In this cross-sectional study, 30 patients with oral lichen planus receiving long-term (>6 weeks) clobetasol propionate gel 0.025% were invited to participate. Adrenal function was assessed by measuring morning plasma cortisol after a 48-h withdrawal of clobetasol treatment. In patients with plasma cortisol <280 nmol/L, a cosyntropin stimulation test was performed.

RESULTS

Twenty-seven patients were included. Twenty-one (78%) patients presented with plasma cortisol ≥280 nmol/L (range 280-570 nmol/L), and six (22%) <280 nmol/L (range 13-260 nmol/L). Five of these six patients underwent cosyntropin stimulation that revealed severe adrenal insufficiency in two patients (cortisol peak 150 nmol/L and 210 nmol/L) and mild adrenal insufficiency in three patients (cortisol peak 350-388 nmol/L).

CONCLUSION

In this study, approximately 20% of patients receiving intermittent topical glucocorticoid treatment for oral lichen planus had glucocorticoid-induced adrenal insufficiency. It is essential for clinicians to be aware of this risk and to inform patients about the potential need for glucocorticoid stress doses during intercurrent illness.

Alcohol consumption modulates Candida albicans-induced oral carcinogenesis and progression

OBJECTIVES

This study aimed to determine the impact of low levels of alcohol consumption on the interaction of the oral cavity with Candida albicans, a species that is commonly found at higher levels in the oral cavities of regular alcohol consumers, patients with pre-malignant diseases, and patients with existing oral cancer (OC).

METHODS

The gingival squamous cell carcinoma cell line, Ca9-22, was subjected to low-level ethanol exposure before co-culture with heat-inactivated C. albicans (HICA). We performed cell viability assays, measured reactive oxygen species, and used Western blot analysis for cell death markers to examine the effect of ethanol and HICA on cells. Scratch assays and anchorage-independent growth assays were used to determine cell behavioral changes.

RESULTS

The results showed that ethanol in combination with HICA exacerbated cell death and cell cycle disruption, delayed NF-κB signaling, increased TIMP-2 secretion, and subsequently decreased MMP-2 secretion when compared to exposure to HICA alone. Conversely, both ethanol and HICA independently increased proliferation of Ca9-22 cells in scratch assays, and in combination, increased their capacity for anchorage-independent growth.

CONCLUSION

Low levels of ethanol may provide protective effects against Candida-induced inflammatory oral carcinogenesis or OC progression.

Sub-lethal concentrations of chlorhexidine inhibit Candida albicans growth by disrupting ROS and metal ion homeostasis

Candida albicans is a normal resident of the human oral cavity. It is also the most common fungal pathogen, causing various oral diseases, particularly in immunocompromised individuals. Chlorhexidine digluconate (CHG) is a broad-spectrum antimicrobial agent widely used in dental practice and has been recommended to treat oral candidiasis. However, its action mechanism against the fungal pathogen C. albicans remains poorly understood. The aim of the present study was to investigate the effect of CHG at sub-lethal concentrations against C. albicans. CHG inhibited the growth of C. albicans in a dose- and time-dependent manner. Cells treated with CHG exhibited altered membrane permeability, reduced metabolic activity, and enhanced metal ion and reactive oxygen species (ROS) accumulation. Copper-sensing transcription factor Mac1, iron-sensing transcription factors Sfu1 and Sef2, and copper transporter Ctr1 regulated intracellular metal ion and ROS homeostasis in response to CHG. Deletion of MAC1, SFU1, or SEF2 increased intracellular ROS production and cell susceptibility to CHG. This study revealed a novel mechanism by which CHG induced apoptosis of C. albicans cells through the disruption of metal ion and ROS homeostasis, which may help to identify new targets for fungal infections.

Host Cell Geometry and Cytoskeletal Organization Governs Candida-Host Cell Interactions at the Nanoscale

Candida is one of the most common opportunistic fungal pathogens in humans. Its adhesion to the host cell is required in parasitic states and is important for pathogenesis. Many studies have shown that there is an increased risk of developing candidiasis when normal tissue barriers are weakened or when immune defenses are compromised, for example, during cancer treatment that induces immunosuppression. The mechanical properties of malignant cells, such as adhesiveness and viscoelasticity, which contribute to cellular invasion and migration are different from those of noncancerous cells. To understand host invasion and its relationship with host cell health, we probed the interaction of Candida spp. with cancerous and noncancerous human cell lines using atomic force microscopy in the single-cell force spectroscopy mode. There was significant adhesion between Candida and human cells, with more adhesion to cancerous versus noncancerous cell lines. This increase in adhesion is related to the mechanobiological properties of cancer cells, which have a disorganized cytoskeleton and lower rigidity. Altered geometry and cytoskeletal disruption of the human cells impacted adhesion parameters, underscoring the role of cytoskeletal organization in Candida-human cell adhesion and implicating the manipulation of cell properties as a potential future therapeutic strategy.

The emerging role of oral microbiota in oral cancer initiation, progression and stemness

Oral squamous cell carcinoma (OSCC) is the most prevalent malignancy among the Head and Neck cancer. OSCCs are highly inflammatory, immune-suppressive, and aggressive tumors. Recent sequencing based studies demonstrated the involvement of different oral microbiota in oral cavity diseases leading OSCC carcinogenesis, initiation and progression. Researches showed that oral microbiota can activate different inflammatory pathways and cancer stem cells (CSCs) associated stemness pathways for tumor progression. We speculate that CSCs and their niche cells may interact with the microbiotas to promote tumor progression and stemness. Certain oral microbiotas are reported to be involved in dysbiosis, pre-cancerous lesions, and OSCC development. Identification of these specific microbiota including Human papillomavirus (HPV), Porphyromonas gingivalis (PG), and Fusobacterium nucleatum (FN) provides us with a new opportunity to study the bacteria/stem cell, as well as bacteria/OSCC cells interaction that promote OSCC initiation, progression and stemness. Importantly, these evidences enabled us to develop in-vitro and in-vivo models to study microbiota interaction with stem cell niche defense as well as CSC niche defense. Thus in this review, the role of oral microbiota in OSCC has been explored with a special focus on how oral microbiota induces OSCC initiation and stemness by modulating the oral mucosal stem cell and CSC niche defense.

Candida species as potential risk factors for oral squamous cell carcinoma: Systematic review and meta-analysis

Oral squamous cell carcinoma (OSCC) is considered a multifactorial disease and has been associated with microbial infections, although the association with Candida spp. is still controversial. This systematic review focused on clinical trials which evaluated the relation between oral Candida spp colonization and OSCC. PubMed; Scopus; Embase; Web of Science and Scientific Direct were assessed. Independent reviewers conducted the diagram steps. For data extraction the PRISMA protocol was followed. The quality analysis of case-control studies was performed based on the Newcastle-Ottawa scale. Meta-analysis was performed to evaluate the frequency of Candida spp and the levels of microbial acetaldehyde production (MAP) being odds ratio (OR) the effect-measure applied. Eight and six studies were included in the qualitative analysis and meta-analysis, respectively. It was noted that there was a significantly higher frequency of Candida species (p = 0.0003/OR = 9.50) in patients diagnosed with OSCC than healthy patients, especially Candida krusei (p = 0.0167/OR=4.62). Candida spp., from oral cancer patients demonstrated significantly greater biofilm, biofilm metabolic activity, phospholipase, proteinase activity and a higher production of MAP (p = 0.0111/OR = 2.67). Candida species may have a potential role in OSCC development. Further studies should be conducted to elucidate the mechanism of action of Candida spp and others risk factors in the development of OSCC.

Presence of Candida and its associated factors in participants attending oral cancer screening in the lower northeastern area of Thailand

BACKGROUND

Certain evidence indicated high prevalence of Candida in oral potentially malignant disorders (OPMDs) and oral cancer (OC). This study was aimed to investigate the presence of Candida and its associated factors in participants who attended the oral cancer screening program in the lower northeastern districts of Thailand.

METHODS

Convenient participants residing in the lower northeastern districts of Thailand who attended the oral cancer screening were enrolled. A questionnaire retrieving demographic characteristics, risk factors of oral cancer, and risk of having Candida was completed. Oral examination was performed by oral medicine specialists or oral surgeons. The participants were categorized into 4 groups according to their clinical diagnosis, namely normal oral mucosa (NOM), OPMDs/OC, non-OPMDs/OC and clinically suspected oral candidiasis (CSOC). Stimulated saliva flow rate was measured. Dip-slide test was performed in each participant to evaluate the presence of Candida. The levels of Candida were categorized into high and low levels according to the score received from the dip-slide test. Factors associated with high levels of Candida were identified using multivariate logistic regression analysis.

RESULTS

A total of 577 participants were recruited. High levels of Candida were found in 31.3%, 24.7%, 25.9% and 18.1% in the OPMDs/OC, the non-OPMDs/OC, the CSOC and the NOM groups, respectively. According to multivariate logistic regression analysis, age above 60 years, female gender, betel quid chewing habit, use of denture, hyposalivation, and being in the CSOC group were found to be significantly associated with high levels of Candida.

CONCLUSION

Higher number of participants in the OPMDs/OC group was found to have high levels of Candida. Increasing age, female gender, betel quid chewing habit, use of denture, hyposalivation and having CSOC lesions were associated with high levels of Candida.

Oral Potentially Malignant Disorders and Candida in Oral Tongue Squamous Cell Carcinoma Patients

This retrospective study addressed the role of oral potentially malignant disorders and the presence of intraepithelial Candida hyphae in the carcinogenesis of the oral tongue squamous cell carcinoma and its association with smoking, alcohol consumption, and oral inflammatory burden. The medical records of 183 subjects diagnosed with oral tongue squamous cell carcinoma at the Helsinki University Hospital were investigated. Preceding oral lichen planus, lichenoid reaction, and leukoplakia diagnosis were recorded. Further, the data on Candida hyphae in histological samples as an indicator of oral candidiasis, oral inflammatory burden, smoking, and alcohol consumption were recorded and analyzed. The histopathological diagnosis of oral lichen planus/lichenoid reaction (p < 0.001) and the presence of Candida hyphae (p = 0.005) were associated significantly with female gender. Oral lichen planus/lichenoid reaction patients were less often smokers than patients without these lesions. Candida hyphae were more often recorded in patients without alcohol use (p = 0.012). Oral lichen planus/lichenoid reaction and Candida hyphae in histological samples were associated with female gender and lower levels of typical risk factors, such as alcohol use and smoking, in oral tongue squamous cell carcinoma patients. Therefore, these patients should be well monitored despite a potential lack of the classical risk factors of oral carcinoma.

Candida albicans Promotes Oral Cancer via IL-17A/IL-17RA-Macrophage Axis

The association between Candida albicans (C. albicans) and oral cancer (OC) has been noticed for a long time, but the mechanisms for C. albicans promoting OC are rarely explored. In this study, we determined that C. albicans infection promoted OC incidence in a 4-nitroquinoline 1-oxide (4NQO)-induced mouse tongue carcinogenesis model as well as promoted OC progression in a tongue tumor-bearing mouse model (C3H/HeN-SCC VII). We then demonstrated that tumor-associated macrophage (TAMs) infiltration was elevated during C. albicans infection. Meanwhile, the attracted TAMs polarized into M2-like macrophages with high expression of programmed death ligand 1 (PD-L1) and galectin-9 (GAL-9). Further analysis suggested that the interleukin (IL)-17A/IL-17RA pathway activated in OC cells was a contributor to the excessive TAMs infiltration in C. albicans-infected mice. Thus, we constructed IL-17A neutralization and macrophage depletion experiments in C3H/HeN-SCC VII mice to explore the role of IL-17A/IL-17RA and TAMs in OC development caused by C. albicans infection. The results showed that both IL-17A neutralization and macrophage depletion tended to reduce the TAMs number and tumor size in mice with C. albicans infection. Collectively, our finding revealed that C. albicans promoted OC development via the IL-17A/IL-17RA-macrophage axis, opening perspectives for revealing C. albicans-tumor immune microenvironment links. IMPORTANCE The relationship between fungi and cancer is gradually receiving attention. Among them, some clinical evidence has shown that Candida may be a contributor to gastrointestinal cancers, especially oral cancer. However, the underlying mechanisms for Candida promoting oral cancer need to be explored. For this reason, this study demonstrated the role of C. albicans in oral cancer development. Moreover, this study revealed the underlying mechanisms for C. albicans promoting oral cancer from the perspective of the tumor immune microenvironment.

The Protective Role of Cranberries and Blueberries in Oral Cancer

BACKGROUND

Oral cancer has a high prevalence worldwide, and this disease is caused by genetic, immunological, and environmental factors. The main risk factors associated with oral cancer are smoking and alcohol.

RESULTS

There are various strategies to reduce risk factors, including prevention programs as well as the consumption of an adequate diet that includes phytochemical compounds derived from cranberries (Vaccinium macrocarpon A.) and blueberries (Vaccinium corymbosum L.); these compounds exhibit antitumor properties.

RESULTS

The main outcome of this review is as follows: the properties of phytochemicals derived from cranberries were evaluated for protection against risk factors associated with oral cancer.

CONCLUSIONS

The secondary metabolites of cranberries promote biological effects that provide protection against smoking and alcoholism. An alternative for the prevention of oral cancer can be the consumption of these cranberries and blueberries.

The Influence of the Oral Microbiome on Oral Cancer: A Literature Review and a New Approach

In our recent article (Smędra et al.: Oral form of auto-brewery syndrome. J Forensic Leg Med. 2022; 87: 102333), we showed that alcohol production can occur in the oral cavity (oral auto-brewery syndrome) due to a disruption in the microbiota (dysbiosis). An intermediate step on the path leading to the formation of alcohol is acetaldehyde. Typically, acetic aldehyde is transformed into acetate particles inside the human body via acetaldehyde dehydrogenase. Unfortunately, acetaldehyde dehydrogenase activity is low in the oral cavity, and acetaldehyde remains there for a long time. Since acetaldehyde is a recognised risk factor for squamous cell carcinoma arising from the oral cavity, we decided to analyse the relationship linking the oral microbiome, alcohol, and oral cancer using the narrative review method, based on browsing articles in the PubMed database. In conclusion, enough evidence supports the speculation that oral alcohol metabolism must be assessed as an independent carcinogenic risk. We also hypothesise that dysbiosis and the production of acetaldehyde from non-alcoholic food and drinks should be treated as a new factor for the development of cancer.

Tumour Necrosis Factor Alpha (TNF-α) and Oral Squamous Cell Carcinoma

Uncovering the inflammatory mechanisms underpinning initiation, progression, and promotion of oral squamous cell carcinoma (OSCC) development is fundamental to the rational pursuit of targeted therapeutics. Here we present a review of the current knowledge of the role of TNF-α in the aetiology, pathogenesis, and potential therapies with regards to OSCC. TNF-α is worthy of particular attention in OSCC, with its presence demonstrated to enhance cell proliferation and its downregulation demonstrated to inhibit proliferation and migration in other carcinomas in both in vitro and in vivo models and oral cancer patients. Increased TNF-α in the OSCC tumour microenvironment has been demonstrated to favour invasion through promotion of firstly the pro-inflammatory, pro-invasive phenotypes of OSCC cells and secondly its paracrine mechanism mediating recruitment and activation of inflammatory cells. Polymorphisms affecting the gene expression of TNF-α have been strongly associated with an increased risk for oral squamous cell carcinoma. A number of studies have considered TNF-α within biofluids, including saliva and serum, as a potential biomarker for the early detection of OSCC, as well as its staging, differentiation, and prognosis. The broad and multifaceted role that TNF-α plays in many inflammatory states presents an obvious confounder, particularly with demonstrated increased TNF-α levels in common oral disease states. Lastly, biologic agents targeting TNF-α are currently in clinical use for immune-mediated inflammatory rheumatological and gastrointestinal diseases. There is the potential that these biological agents might have an adjunctive role in OSCC prevention and treatment.

Is Candida albicans a contributor to cancer? A critical review based on the current evidence

The association between Candida albicans (C. albicans) and cancer has been noticed for decades. Whether C. albicans infection is a complication of cancer status or as a contributor to cancer development remains to be discussed. This review systematically summarized the up-to-date knowledge about associations between C. albicans and various types of cancer, and discussed the role of C. albicans in cancer development. Most of the current clinical and animal evidence support the relationship between C. albicans and oral cancer development. However, there is insufficient evidence to demonstrate the role of C. albicans in other types of cancer. Moreover, this review explored the underlying mechanisms for C. albicans promoting cancer. It was hypothesized that C. albicans may promote cancer progression by producing carcinogenic metabolites, inducing chronic inflammation, remodeling immune microenvironment, activating pro-cancer signals, and synergizing with bacteria.

Oral dysbiosis in the onset and carcinogenesis of oral epithelial dysplasia: A systematic review

OBJECTIVE

This systematic review aims to investigate possible connections between the oral microbiome and the onset and carcinogenesis of oral epithelial dysplasia (OED).

METHODS

A systematic search was performed on PubMed, Embase, Cochrane Database, and SCOPUS by two authors independently, addressing the focused question- "Has oral microbiome dysbiosis been involved in the onset and carcinogenesis of oral epithelial dysplasia?" We used the Newcastle-Ottawa scale to assess the quality of studies included in the review.

RESULTS

Out of 580 references screened, ten studies were found eligible for inclusion. All studies were case-control studies, and only qualitative analysis was conducted due to heterogeneous characteristics. The overall risk of bias in the eligible studies was considered as high. Microbiome diversity indices showed inconsistent evidence among studies. A significant increase of phylum Bacteroidetes in OED patients was reported in five studies. Five studies reported an increase of genus Fusobacterium in both the OED and oral squamous cell carcinoma (OSCC) patients and six different studies respectively reported a reduction of genus Streptococcus in both the OED and OSCC groups when compared to normal controls. Other predominant bacteria that were specific to different patient groups varied in each study.

CONCLUSIONS

The results of the included studies showed that the composition of the oral microbiome in patients with OED compared to healthy controls and OSCC patients was inconsistent. However, all ten studies showed non-negligible heterogeneity in the type and size of the sample, and the comparability between groups, which strongly limited the external validity of results. Further studies are strongly recommended.

Extracellular lipids of Candida albicans biofilm induce lipid droplet formation and decreased response to a topoisomerase I inhibitor in dysplastic and neoplastic oral cells

OBJECTIVE

Some microorganisms, i.e., Candida albicans, have been associated with cancer onset and development, although whether the fungus promotes cancer or whether cancer facilitates the growth of C. albicans is unclear. In this context, microbial-derived molecules can modulate the growth and resistance of cancer cells. This study isolated extracellular lipids (ECL) from a 36-h Candida albicans biofilm incubated with oral dysplastic (DOK) and neoplastic (SCC 25) cells, which were further challenged with the topoisomerase I inhibitor camptothecin (CPT), a lipophilic anti-tumoral molecule.

METHODOLOGY

ECL were extracted from a 36-h Candida albicans biofilm with the methanol/chloroform precipitation method and identified with Nuclear Magnetic Resonance (1H-NMR). The MTT tetrazolium assay measured ECL cytotoxicity in DOK and SCC 25 cells, alamarBlue™ assessed cell metabolism, flow cytometry measured cell cycle, and confocal microscopy determined intracellular features.

RESULTS

Three major classes of ECL of C. albicans biofilm were found: phosphatidylinositol (PI), phosphatidylcholine (PC), and phosphatidylglycerol (PG). The ECL of C. albicans biofilm had no cytotoxic effect on neither cell after 24 hours, with a tendency to disturb the SCC 25 cell cycle profile (without statistical significance). The ECL-induced intracellular lipid droplet (LD) formation on both cell lines after 72 hours. In this context, ECL enhanced cell metabolism, decreased the response to CPT, and modified intracellular drug distribution.

CONCLUSION

The ECL (PI, PC, and PG) of 36-h Candida albicans biofilm directly interacts with dysplastic and neoplastic oral cells, highlighting the relevance of better understanding C. albicans biofilm signaling in the microenvironment of tumor cells.

Advances in the oral microbiota and rapid detection of oral infectious diseases

Several studies have shown that the dysregulation of the oral microbiota plays a crucial role in human health conditions, such as dental caries, periodontal disease, oral cancer, other oral infectious diseases, cardiovascular diseases, diabetes, bacteremia, and low birth weight. The use of traditional detection methods in conjunction with rapidly advancing molecular techniques in the diagnosis of harmful oral microorganisms has expanded our understanding of the diversity, location, and function of the microbiota associated with health and disease. This review aimed to highlight the latest knowledge in this field, including microbial colonization; the most modern detection methods; and interactions in disease progression. The next decade may achieve the rapid diagnosis and precise treatment of harmful oral microorganisms.

Oral microbiome and risk of incident head and neck cancer: A nested case-control study

OBJECTIVES

This nested case-control study in the NIH-AARP Diet and Health Study was carried out to prospectively investigate the relationship of oral microbiome with head and neck cancer (HNC).

MATERIALS AND METHODS

56 incident HNC cases were identified, and 112 controls were incidence-density matched to cases. DNA extracted from pre-diagnostic oral wash samples was whole-genome shotgun metagenomic sequenced to measure the overall oral microbiome. ITS2 gene qPCR was used to measure the presence of fungi. ITS2 gene sequencing was performed on ITS2 gene qPCR positive samples. We computed taxonomic and functional alpha-diversity and beta-diversity metrics. The presence and relative abundance of groups of red-complex (e.g., Porphyromonas gingivalis) and/or orange-complex (e.g., Fusobacterium nucleatum) periodontal pathogens were compared between cases and controls using conditional logistic regression models and MiRKAT.

RESULTS

Participants with higher taxonomic microbial alpha-diversity had a non-statistically significant decreased risk of HNC. No case-control differences were found for beta diversity by MiRKAT model (all p > 0.05). A greater relative abundance of red-complex periodontal pathogens (OR = 0.51, 95 % CI = 0.26-1.00), orange-complex (OR = 0.38, 95 % CI = 0.18-0.83), and both complexes' pathogens (OR = 0.32, 95 % CI = 0.14-0.75), were associated with reduced risk of HNC. The presence of oral fungi was also strongly associated with reduced risk of HNC compared with controls (OR = 0.39, 95 % CI = 0.17-0.92).

CONCLUSION

Greater taxonomic alpha-diversity, the presence of oral fungi, and the presence or relative abundance of multiple microbial species, including the red- and orange-complex periodontal pathogens, were associated with reduced risk of HNC. Future studies with larger sample sizes are needed to evaluate these associations.

Role of oral microbiome in oral oncogenesis, tumor progression, and metastasis

Squamous cell carcinoma is the most common malignant tumor of the oral cavity and its adjacent sites, which endangers the physical and mental health of patients and has a complex etiology. Chronic infection is considered to be a risk factor in cancer development. Evidence suggests that periodontal pathogens, such as Porphyromonas gingivalis, Fusobacterium nucleatum, and Treponema denticola, are associated with oral squamous cell carcinoma (OSCC). They can stimulate tumorigenesis by promoting epithelial cells proliferation while inhibiting apoptosis and regulating the inflammatory microenvironment. Candida albicans promotes OSCC progression and metastasis through multiple mechanisms. Moreover, oral human papillomavirus (HPV) can induce oropharyngeal squamous cell carcinoma (OPSCC). There is evidence that HPV16 can integrate with host cells' DNA and activate oncogenes. Additionally, oral dysbiosis and synergistic effects in the oral microbial communities can promote cancer development. In this review, we will discuss the biological characteristics of oral microbiome associated with OSCC and OPSCC and then highlight the mechanisms by which oral microbiome is involved in oral oncogenesis, tumor progression, and metastasis. These findings may have positive implications for early diagnosis and treatment of oral cancer.

Topical Chinese herbal compound in the treatment of oral candidiasis: A systematic review and meta-analysis of randomized controlled trials

Objective

A meta-analysis was performed to systematically review the clinical efficacy of external traditional Chinese medicine compounds in the treatment of oral candidiasis to provide a reference for the clinical treatment of this disease.

Methods

We systematically searched relevant Chinese and English databases, including the Chinese Biomedical Literature Database, China National Knowledge Infrastructure, Chinese Scientific Journal Database, Wanfang Database, PubMed, Web of Science, the Cochrane Library and Scopus, from inception to September 2022 to identify all clinical randomized controlled studies of oral candidiasis treated with external Chinese medicine compounds. The inclusion criteria were a randomized controlled study of an experimental group with the intervention of an external traditional Chinese medicine compound, and the results of the literature were clear. Duplicate publications, literature on single or proprietary Chinese medicine treatment, literature from which relevant data could not be extracted and studies without rigorous experimental designs were excluded. Two researchers independently screened relevant studies that met the inclusion and exclusion criteria and conducted quality evaluation and data extraction for the included studies. The total effective rate, Candida negative conversion rate and recurrence rate were statistically analysed by RevMan 5.3 software.

Results

This study included 29 studies and 30 studies, involving 2553 patients with oral candidiasis, with 1320 in the experimental group and 1233 in the control group. The total effective rate of the experimental group was better than that of the control group (RR = 1.21 [1.15, 1.27], P < 0.000). The negative rate of Candida in the experimental group was better than that in the control group (RR = 1.25 [1.05, 1.50], P=0.01). The recurrence rate of the experimental group was lower than that of the control group (RR = 0.34 [0.18, 0.63], P=0.0007). The difference was statistically significant.

Conclusion

Compared with Western medicine alone, external traditional Chinese medicine in the treatment of oral candidiasis has certain advantages in improving the total effective rate, increasing the negative conversion rate of Candida and reducing the recurrence rate. However, larger samples and high-quality clinical studies are needed to obtain further support and verification.

Current Infections of the Orofacial Region: Treatment, Diagnosis, and Epidemiology

Undoubtedly, diagnosing and managing infections is one of the most challenging issues for orofacial clinicians. As a result of the diversity of symptoms, complicated behavior, and sometimes confusing nature of these conditions, it has become increasingly difficult to diagnose and treat them. It also highlights the need to gain a deeper insight into the orofacial microbiome as we try to improve our understanding of it. In addition to changes in patients' lifestyles, such as changes in diet, smoking habits, sexual practices, immunosuppressive conditions, and occupational exposures, there have been changes in patients' lifestyles that complicate the issue. Recent years have seen the development of new infection treatments due to the increased knowledge about the biology and physiology of infections. This review aimed to provide a comprehensive overview of the types of infections in the mouth, including the types that viruses, fungi, or bacteria may cause. It is important to note that we searched the published literature in the Scopus, Medline, Google Scholar, and Cochran databases from 2010 to 2021 using the following keywords: "Orofacial/Oral Infections," "Viral/Fungal/Bacterial Infections", "Oral Microbiota" And "Oral Microflora" without limiting our search to languages and study designs. According to the evidence, the most common infections in the clinic include herpes simplex virus, human papillomavirus, Candida albicans, Aspergillus, Actinomycosis, and Streptococcus mutans. The purpose of this study is to review the new findings on characteristics, epidemiology, risk factors, clinical manifestations, diagnosis, and new treatment for these types of infectious diseases.

Role of Candida albicans in Oral Carcinogenesis

Oral carcinogenesis is also dependent on the balance of the oral microbiota. Candida albicans is a member oral microbiota that acts as an opportunistic pathogen along with changes in the epithelium that can predispose to premalignancy and/or malignancy. This systematic review uses the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines to analyze the role of Candida albicans in the process of oral carcinogenesis. Eleven articles qualified inclusion criteria, matched keywords, and provided adequate information about the carcinogenesis parameters of Candida albicans in oral cancer. Candida albicans in oral carcinogenesis can be seen as significant virulent factors for patients with oral squamous cell carcinoma (OSCC) or potentially malignant disorder (OPMD) with normal adjacent mucosa. Candida albicans have a role in the process of oral carcinogenesis concerning morphological phenotype changes in cell structure and genotype and contribute to the formation of carcinogenic substances that can affect cell development towards malignancy.

The research progress in the interaction between Candida albicans and cancers

Candida albicans is an opportunistic pathogenic fungus, which tends to infect the host with defective immune function including cancer patients. A growing number of studies have shown that C. albicans infection increases the host susceptibility to cancer such as oral, gastric, and colorectal cancer. Cancer and anti-cancer treatment may also affect the colonization of C. albicans. C. albicans may promote the development of cancer by damaging mucosal epithelium, inducing the production of carcinogens, triggering chronic inflammation including Th17 cell-mediated immune response. In this article, we aim to elaborate the interaction between C. albicans and cancers development and summarize the potential molecular mechanisms, so as to provide theoretical basis for prevention, diagnosis and treatment of cancers.

The oral mycobiome: Oral epithelial dysplasia and oral squamous cell carcinoma

Fungi, a diverse group of eukaryotic organisms, play distinct roles in health and disease. Recent advances in the field of mycobiology have enabled the characterization of the "human mycobiome." The human mycobiome has extensively been studied in various disease models. However, to date, the role of the oral mycobiome in oral carcinogenesis has yet to be elucidated. Candida albicans, the most common oral colonizer, has been speculated to display tumorigenic effects; however, the literature lacks consistent documentation from mechanistic studies on whether oral mycobiota act as drivers, facilitators, or passive colonizers of oral premalignancy and cancer. This review article provides an overview of existing hypothesis-driven mechanistic models that outline the complex interplay between the oral mycobiome and oral epithelial dysplasia as well as their potential clinical implications.

The World of Oral Cancer and Its Risk Factors Viewed from the Aspect of MicroRNA Expression Patterns

Oral cancer is one of the leading causes of death worldwide, with a reported 5-year survival rate of around 50% after treatment. Epigenetic modifications are considered to have a key role in oral carcinogenesis due to histone modifications, aberrant DNA methylation, and altered expression of miRNAs. MicroRNAs (miRNAs) are small non-coding RNAs that have a key role in cancer development by regulating signaling pathways involved in carcinogenesis. MiRNA deregulation identified in oral cancer has led to the idea of using them as potential biomarkers for early diagnosis, prognosis, and the development of novel therapeutic strategies. In recent years, a key role has been observed for risk factors in preventing and treating this malignancy. The purpose of this review is to summarize the recent knowledge about the altered mechanisms of oral cancer due to risk factors and the role of miRNAs in these mechanisms.

Fungal Colonization and Infections-Interactions with Other Human Diseases

Candida albicans is a commensal fungus that asymptomatically colonizes the skin and mucosa of 60% of healthy individuals. Breaches in the cutaneous and mucosal barriers trigger candidiasis that ranges from asymptomatic candidemia and mucosal infections to fulminant sepsis with 70% mortality rates. Fungi influence at least several diseases, in part by mechanisms such as the production of pro-carcinogenic agents, molecular mimicking, and triggering of the inflammation cascade. These processes impact the interactions among human pathogenic and resident fungi, the bacteriome in various organs/tissues, and the host immune system, dictating the outcomes of invasive infections, metabolic diseases, and cancer. Although mechanistic investigations are at stages of infancy, recent studies have advanced our understanding of host-fungal interactions, their role in immune homeostasis, and their associated pathologies. This review summarizes the role of C. albicans and other opportunistic fungi, specifically their association with various diseases, providing a glimpse at the recent developments and our current knowledge in the context of inflammatory-bowel disease (IBD), cancers, and COVID-19. Two of the most common human diseases where fungal interactions have been previously well-studied are cancer and IBD. Here we also discuss the emerging role of fungi in the ongoing and evolving pandemic of COVID-19, as it is relevant to current health affairs.

Microbial Colonization and Inflammation as Potential Contributors to the Lack of Therapeutic Success in Oral Squamous Cell Carcinoma

This review discusses the microenvironment of evolving and established conventional oral squamous cell carcinoma, by far the most common oral cancer. The focus of this paper is mainly on the more recent data that describe the role of microorganisms, host-microbial interactions, and in particular, the contributions of cell-surface toll-like receptors on immune system cells and on normal and malignant epithelial cells to their functions that support carcinogenesis. Because carcinomas arising at various host surfaces share much in common, additional information available from studies of other carcinomas is included in the discussion. Accumulating evidence reveals the complex toll-like receptor-mediated tumor-supporting input into many aspects of carcinogenesis via malignant cells, stromal immune cells and non-immune cells, complicating the search for effective treatments.

Head and Neck Squamous Cell Carcinoma: Risk Factors, Molecular Alterations, Immunology and Peptide Vaccines

Head and neck squamous cell carcinoma (HNSCC) arises from the epithelial lining of the oral cavity, hypopharynx, oropharynx, and larynx. There are several potential risk factors that cause the generation of HNSCC, including cigarette smoking, alcohol consumption, betel quid chewing, inadequate nutrition, poor oral hygiene, HPV and Epstein–Barr virus, and Candida albicans infections. HNSCC has causative links to both environmental factors and genetic mutations, with the latter playing a more critical role in cancer progression. These molecular changes to epithelial cells include the inactivation of cancer suppressor genes and proto-oncogenes overexpression, resulting in tumour cell proliferation and distant metastasis. HNSCC patients have impaired dendritic cell (DC) and natural killer (NK) cell functions, increased production of higher immune-suppressive molecules, loss of regulatory T cells and co-stimulatory molecules and major histocompatibility complex (MHC) class Ι molecules, lower number of lymphocyte subsets, and a poor response to antigen-presenting cells. At present, the standard treatment modalities for HNSCC patients include surgery, chemotherapy and radiotherapy, and combinatorial therapy. Despite advances in the development of novel treatment modalities over the last few decades, survival rates of HNSCC patients have not increased. To establish effective immunotherapies, a greater understanding of interactions between the immune system and HNSCC is required, and there is a particular need to develop novel therapeutic options. A therapeutic cancer vaccine has been proposed as a promising method to improve outcome by inducing a powerful adaptive immune response that leads to cancer cell elimination. Compared with other vaccines, peptide cancer vaccines are more robust and specific. In the past few years, there have been remarkable achievements in peptide-based vaccines for HNSCC patients. Here, we summarize the latest molecular alterations in HNSCC, explore the immune response to HNSCC, and discuss the latest developments in peptide-based cancer vaccine strategies. This review highlights areas for valuable future research focusing on peptide-based cancer vaccines.

Human Gut Microbiota in Health and Selected Cancers

The majority of the epithelial surfaces of our body, and the digestive tract, respiratory and urogenital systems, are colonized by a vast number of bacteria, archaea, fungi, protozoans, and viruses. These microbiota, particularly those of the intestines, play an important, beneficial role in digestion, metabolism, and the synthesis of vitamins. Their metabolites stimulate cytokine production by the human host, which are used against potential pathogens. The composition of the microbiota is influenced by several internal and external factors, including diet, age, disease, and lifestyle. Such changes, called dysbiosis, may be involved in the development of various conditions, such as metabolic diseases, including metabolic syndrome, type 2 diabetes mellitus, Hashimoto's thyroidis and Graves' disease; they can also play a role in nervous system disturbances, such as multiple sclerosis, Alzheimer's disease, Parkinson's disease, and depression. An association has also been found between gut microbiota dysbiosis and cancer. Our health is closely associated with the state of our microbiota, and their homeostasis. The aim of this review is to describe the associations between human gut microbiota and cancer, and examine the potential role of gut microbiota in anticancer therapy.

Fusobacterium nucleatum and oral cancer: a critical review

There is a growing level of interest in the potential role inflammation has on the initiation and progression of malignancy. Notable examples include Helicobacter pylori-mediated inflammation in gastric cancer and more recently Fusobacterium nucleatum-mediated inflammation in colorectal cancer. Fusobacterium nucleatum is a Gram-negative anaerobic bacterium that was first isolated from the oral cavity and identified as a periodontal pathogen. Biofilms on oral squamous cell carcinomas are enriched with anaerobic periodontal pathogens, including F. nucleatum, which has prompted hypotheses that this bacterium could contribute to oral cancer development. Recent studies have demonstrated that F. nucleatum can promote cancer by several mechanisms; activation of cell proliferation, promotion of cellular invasion, induction of chronic inflammation and immune evasion. This review provides an update on the association between F. nucleatum and oral carcinogenesis, and provides insights into the possible mechanisms underlying it.

Influence of topical corticosteroids on malignant transformation of oral lichen planus

BACKGROUND

Oral lichen planus (OLP) is considered an oral potentially malignant disorder. While OLP has been associated with the development of oral squamous cell carcinoma (OSCC), little is known about the role of topical corticosteroids therapy (TCT) in the promotion of carcinogenesis. The study aimed to determine if TCT influences the time of malignant transformation of OLP to OSCC. The study also investigates this correlation in the presence or absence of Candida overgrowth, and in the context of conventional OSCC risk factors such as smoking, alcohol use, and male gender.

METHODS

A retrospective analysis of electronic health records at a tertiary care academic medical center was performed. Patients with OLP and OSCC were considered for inclusion. The diagnosis of OLP required both clinical and histological documentation.

RESULTS

Eighty-two patients met inclusion criteria, consisting of 48 women (58.25%) and 34 men (41.5%) and the mean patient age was 65.9 years (SD = 13.25). Forty-five patients (54.9%) received TCT for OLP before they developed OSCC. The time between the OLP and OSCC diagnoses increased by four years in patients who received topical steroid therapy for OLP (p < 0.001) and decreased by three years (p = 0.010) in those with Candida overgrowth. Gender, smoking, and alcohol use did not have a statistically significant influence on the time between OLP and OSCC.

CONCLUSION

The management of OLP using TCT potentially delayed cancer development in our study. Conversely, it appears that Candida may play a role in the field cancerization of OLP patients.

Relationship of Clinical Features with Candidal Carriage in Oral Submucous Fibrosis Patients: A Case-control Study

Background and Objectives:

Oral submucous fibrosis (OSF) is extensively prevalent in India and South-East Asia owing to the habit of arecanut (AN) use. Epithelial atrophy, hyposalivation, and immune alterations in OSF may predispose to increased Candidal carriage. Stomatopyrosis in OSF can result from multiple causes, which may also include Candidal infection. Hence, this study is aimed to assess Candidal carriage, species characterization, salivary flow rate (SFR) and its relationship with the clinical features (stomatopyrosis and mouth opening [MO]) in OSF patients alongwith the response to antifungal treatment in patients with higher Candidal carriage.

Methodology:

In this case-control study, 60 OSF patients and 30 age- and sex-matched control subjects were enrolled. SFR was assessed using modified Schirmer test. Samples for Candidal assessment were collected with the oral rinse technique and cultured. The isolated yeast species were counted and identified based on Gram staining, germ tube test, and CHROMagar. Data were analyzed with Chi-square test, Pearson's correlation test, and one-way ANOVA test.

Results:

The distribution of mean visual analog scale (VAS) score, SFR and MO was significantly varied (P < 0.001) in the study and control groups. Candida was found to be present significantly (P = 0.048) in OSF group as compared to control group. Candida albicans was the predominant species. No statistically significant association was obtained regarding Candidal isolation and SFR, burning sensation and MO in OSF patients. Only 1 patient in the study group yielded a high Candidal carriage (>400 CFU/mL) and reported relief in burning sensation (VAS score) with antifungal therapy.

Conclusions:

OSF patients yielded a significant higher oral Candidal carriage. Although it was not found to be associated directly, its role as a “cause and effect” in SFR and clinical features (stomatopyrosis and MO) of OSF cannot be ignored.

Artemisinin elevates ergosterol levels of Candida albicans to synergise with amphotericin B against oral candidiasis

Oral candidiasis, especially caused by Candida albicans, is the most common fungal infection of the oral cavity. The increase in drug resistance and lack of new antifungal agents call for new strategies of antifungal treatment. This study repurposed artemisinin (Art) as a potentiator to the polyene amphotericin B (AmB) and characterised their synergistic mechanism against C. albicans and oral candidiasis. The synergistic antifungal activity between Art and AmB was identified by the checkerboard and recovery plate assays according to the fractional inhibitory concentration index (FICI). Art showed no antifungal activity even at >200 mg/L. However, it significantly reduced AmB dosages against the wild-type strain and 75 clinical isolates of C. albicans (FICI ≤ 0.5). Art significantly upregulated expression of genes from the ergosterol biosynthesis pathway (ERG1, ERG3, ERG9 and ERG11), as shown by RT-qPCR, and elevated the ergosterol content of Candida cells. Increased ergosterol content significantly enhanced binding between fungal cells and the polyene agent, resulting in sensitisation of C. albicans to AmB. Drug combinations of Art and AmB showed synergistic activity against oral mucosal infection in vivo by reducing the epithelial infection area, fungal burden and inflammatory infiltrates in murine oropharyngeal candidiasis. These findings indicate a novel synergistic antifungal drug combination and a new Art mechanism of action, suggesting that drug repurposing is a clinically practical means of antifungal drug development and treatment of oral candidiasis.

Risk-Based Estimate of Human Fungal Disease Burden, China

We conducted a systematic literature review to obtain risk population–based fungal disease incidence or prevalence data from China. Data were categorized by risk factors and extrapolated by using most recent demographic figures. A total of 71,316,101 cases (5.0% of the population) were attributed to 12 risk factors and 17 fungal diseases. Excluding recurrent Candida vaginitis (4,057/100,000 women) and onychomycosis (2,600/100,000 persons), aspergillosis (317/100,000 persons) was the most common problem; prevalence exceeded that in most other countries. Cryptococcal meningitis, an opportunistic infection, occurs in immunocompetent persons almost twice as often as AIDS. The pattern of fungal infections also varies geographically; Talaromyces marneffei is distributed mainly in the Pearl River Basin, and the Yangtze River bears the greatest histoplasmosis burden. New host populations, new endemic patterns, and high fungal burdens in China, which caused a huge impact on public health, underscore the urgent need for building diagnostic and therapeutic capacity.

Candida albicans and Oral Carcinogenesis. A Brief Review

Current medical knowledge and research on patients’ management are still evolving, and several protocols on minimizing risk of infection by Candida spp. among the population have developed. The aim of this work is to review the epidemiological and biomolecular characteristics and the various histopathological carcinogenesis hypothesis mechanisms that can occur during Candida albicans infections. Current evidence from the literature on the role of C. albicans during potentially malignant oral disorders and oral cancer has been sought. Thus, these biomolecular processes can give or contribute to benign lesions, also in precancerous or cancerous situations. Alongside this, the physiological microorganism oral flora (microbiota) can play a crucial role in maintaining oral health during those infections and therefore avoid carcinogenesis.

Bifacial biological effects of ethanol: acetaldehyde production by oral Streptococcus species and the antibacterial effects of ethanol against these bacteria

Background:Many previous studies have focused on the acetaldehyde produced from ethanol by oral bacteria as a risk factor for oral cancer. Most of these studies involved low ethanol concentrations (ca. 10 mM), but oral bacteria are exposed to a wide range of ethanol concentrations (100–10,000 mM) when alcoholic beverages are consumed. In contrast, ethanol is widely used at high concentrations (> 5,000 mM) as an antiseptic/disinfectant, suggesting that ethanol has bifacial biological effects; i.e. it acts as both a metabolic substrate for bacterial acetaldehyde production and an antimicrobial agent.

Materials and methods:We examined the acetaldehyde production from ethanol by oral streptococci and the effects of ethanol exposure on the growth and viability of these bacteria at a wide range of ethanol concentrations (10–10,000 mM).

Results:Acetaldehyde production was the highest at an ethanol concentration of 2,000 mM (2.1–48-fold higher than that seen at an ethanol concentration of 10 mM). Bacterial growth was inhibited by > 1,000 mM of ethanol, and the bacteria did not seem viable in the presence of > 5,000 mM of ethanol, although they still produced acetaldehyde.

Conclusion:Ethanol has bifacial biological effects, and the concentration ranges of these effects overlap.

The association of Candida and antifungal therapy with pro-inflammatory cytokines in oral leukoplakia

OBJECTIVES

To study the association of Candida and antifungal therapy with pro-inflammatory cytokines (PIC) in oral leukoplakia (OL).

MATERIALS AND METHODS

A prospective observational study where immunocompetent adult subjects with OL (30 homogenous (HL), 30 non-homogenous (NHL)) and 30 age and sex-matched healthy controls (C) with no predisposing factors for oral Candida infection were recruited. Sterile cotton swabs and ophthalmic sponges were used to sample the lesion surface in OL and buccal mucosa in C, for direct microscopy and culture for Candida and to determine levels of PIC (IL-6, IL-8. IL-17, TNF-α) by ELISA, respectively. Sampling for PIC was repeated at same sites in OL, 2 weeks after antifungal therapy.

RESULTS

Candida was associated with 55.3% of NHL, 23.3% of HL and 13.3% of C. The oral secretary levels of PIC were raised in NHL as compared to HL and C. The levels of IL-6, IL-8, TNF-α (p<0.001) and IL-17 (p<0.01) were significantly raised in Candida positive NHL while IL-6 (p<0.05) and TNF-α (p<0.01) were significantly raised in Candida positive HL before antifungal treatment. After antifungal treatment, there was significant reduction in PIC in Candida positive NHL and HL.

CONCLUSIONS

Candida infection contributes to the inflammatory milieu in Candida associated OL which increases the risk of carcinogenesis. Antifungal therapy reduces the PIC in Candida associated OL.

CLINICAL RELEVANCE

Identification and elimination of predisposing factors for Candida infection, like cessation of harmful habits, maintenance of oral/denture hygiene, surveillance for Candida and antifungal therapy at intervals, are recommended in OL.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT04712929.

Extracellular Vesicle-Mediated Chemoresistance in Oral Squamous Cell Carcinoma

Oral Squamous Cell Carcinoma (OSCC) remains a cancer with poor prognosis and high recurrence rate. Even with multimodal treatment options available for OSCC, tumor drug resistance is still a persistent problem, leading to increased tumor invasiveness among OSCC patients. An emerging trend of thought proposes that extracellular vesicles (EVs) play a role in facilitating tumor progression and chemoresistance via signaling between tumor cells. In particular, exosomes and microvesicles are heavily implicated in this process by various studies. Where primary studies into a particular EV-mediated chemoresistance mechanism in OSCC are limited, similar studies on other cancer cell types will be used in the discussion below to provide ideas for a new line of investigation into OSCC chemoresistance. By understanding how EVs are or may be involved in OSCC chemoresistance, novel targeted therapies such as EV inhibition may be an effective alternative to current treatment options in the near future. In this review, the current understandings on OSCC drug mechanisms under the novel context of exosomes and microvesicles were reviewed, including shuttling of miRNA content, drug efflux, alteration of vesicular pH, anti-apoptotic signaling, modulation of DNA damage repair, immunomodulation, epithelial-to-mesenchymal transition and maintenance of tumor by cancer stem cells.

Candida albicans Enhances the Progression of Oral Squamous Cell Carcinoma In Vitro and In Vivo

Oral squamous cell carcinoma (OSCC) is associated with oral Candida albicans infection, although it is unclear whether the fungus promotes the genesis and progression of OSCC or whether cancer facilitates fungal growth. In this study, we investigated whether C. albicans can potentiate OSCC tumor development and progression. In vitro, the presence of live C. albicans, but not Candida parapsilosis, enhanced the progression of OSCC by stimulating the production of matrix metalloproteinases, oncometabolites, protumor signaling pathways, and overexpression of prognostic marker genes associated with metastatic events. C. albicans also upregulated oncogenes in nonmalignant cells. Using a newly established xenograft in vivo mouse model to investigate OSCC-C. albicans interactions, oral candidiasis enhanced the progression of OSCC through inflammation and induced the overexpression of metastatic genes and significant changes in markers of the epithelial-mesenchymal transition. Finally, using the 4-nitroquinoline 1-oxide (4NQO) murine model, we directly correlate these in vitro and short-term in vivo findings with the progression of oncogenesis over the long term. Taken together, these data indicate that C. albicans upregulates oncogenes, potentiates a premalignant phenotype, and is involved in early and late stages of malignant promotion and progression of oral cancer. IMPORTANCE Oral squamous cell carcinoma (OSCC) is a serious health issue worldwide that accounts for 2% to 4% of all cancer cases. Previous studies have revealed a higher yeast carriage and diversity in oral cancer patients than in healthy individuals. Furthermore, fungal colonization in the oral cavity bearing OSCC is higher on the neoplastic epithelial surface than on adjacent healthy surfaces, indicating a positive association between oral yeast carriage and epithelial carcinoma. In addition to this, there is strong evidence supporting the idea that Candida contributes to carcinogenesis events in the oral cavity. Here, we show that an increase in Candida albicans burden promotes an oncogenic phenotype in the oral cavity.

New Insights into Oral Cancer-Risk Factors and Prevention: A Review of Literature

The oral cancer constitutes 48% of head and neck cancer cases. Ninety percent of oral cancer cases are histologically diagnosed as oral squamous cell carcinomas (OSCCs). Despite new management strategies, the 5-year survival rate of oral cancer is still below 50% in most countries. Head and neck cancers are heterogeneous tumors, and this characteristic of them provides a challenge to treatment plan. Due to the poor outcomes in oral cancer, prevention is a necessity. In this review, a relevant English Literature search in PubMed, ScienceDirect, and Google Scholar from 2000 to mid-2018 was performed. All published articles related to oral cancer and its prevention were included. The risk factors of oral cancer and strategies of oral cancer prevention will be discussed.

Oral Candida carriage in smokers and tobacco users: A systematic review and meta-analysis of observational studies

OBJECTIVE

To synthesize evidence from observational studies that evaluated the association between smoking and smokeless tobacco with oral Candida carriage.

METHODS

Following the PRISMA guidelines, we searched through PubMed/MEDLINE, Web of Science, Embase, and Scopus without restrictions until April 2020 for studies that assessed this association. Following study retrieval and selection, relevant data were extracted, and the risk of bias was assessed by two independent authors using the Newcastle-Ottawa Scale. A fixed-effect meta-analysis was performed due to insignificant heterogeneity between studies.

RESULTS

We identified 14 studies that were eligible for inclusion in this review. The pooled odds ratio (OR; six studies) for Candida carriage among smokers and non-smokers was 2.15 (95% confidence interval [CI]: 1.47, 3.14; I2 = 8%; P < 0.0001). The OR (five studies) for Candida carriage among smokeless tobacco users and non-users was 1.77 (95% CI: 1.29, 2.44; I2 = 46%; P = 0.0004).

CONCLUSION

Our findings suggest a significant relationship between smoking/smokeless tobacco users and oral Candida carriage. However, observational studies cannot clarify whether the observed epidemiologic association is a causal effect or the result of some unmeasured confounding variables. Therefore, continued efforts to measure the association between smoking and oral Candida carriage are required.

LDOC1 Suppresses Microbe-Induced Production of IL-1β in Human Normal and Cancerous Oral Cells through the PI3K/Akt/GSK-3β Axis

Simple Summary

Oral microbes often proliferate due to poor oral hygiene (POH). POH is associated with OSCC (oral squamous cell carcinoma). We investigated the role of LDOC1 in the production of IL-1β, an oncogenic proinflammatory cytokine in OSCC, induced by microorganisms in human oral cells. Candida albicans (CA) was detected in OSCC tissues. CA and the oral bacterium Fusobacterium nucleatum stimulate higher levels of IL-1β production in LDOC1-deficient OSCC cells than in LDOC1-expressing oral cells. CA SC5314 increased OSCC incidence in carcinogen-treated mice. Loss and gain of LDOC1 function resulted in increased and decreased, respectively, CA SC5314-induced IL-1β production. LDOC1 deficiency increased active pAkt^S473 upon SC5314 stimulation and inactive pGSK-3β^S9 phosphorylated by pAkt^S473. PI3K and Akt inhibitors and expression of constitutively active mutant GSK-3β^S9A reduced the SC5314-stimulated IL-1β production in LDOC1-deficient cells. These results indicate that the PI3K/Akt/pGSK-3β signaling contributes to LDOC1-mediated inhibition of microbe-induced IL-1β production, suggesting LDOC1 may determine the role of oral microbes in POH-associated OSCC.

Abstract

Poor oral hygiene (POH) is associated with oral squamous cell carcinoma (OSCC). Oral microbes often proliferate due to POH. Array data show that LDOC1 plays a role in immunity against pathogens. We investigated whether LDOC1 regulates the production of oral microbe-induced IL-1β, an oncogenic proinflammatory cytokine in OSCC. We demonstrated the presence of Candida albicans (CA) in 11.3% of OSCC tissues (n = 80). CA and the oral bacterium Fusobacterium nucleatum stimulate higher levels of IL-1β secretion by LDOC1-deficient OSCC cells than by LDOC1-expressing oral cells. CA SC5314 increased OSCC incidence in 4-NQO (a synthetic tobacco carcinogen) and arecoline-cotreated mice. Loss and gain of LDOC1 function significantly increased and decreased, respectively, CA SC5314-induced IL-1β production in oral and OSCC cell lines. Mechanistic studies showed that LDOC1 deficiency increased active phosphorylated Akt upon CA SC5314 stimulation and subsequent inhibitory phosphorylation of GSK-3β^S9 by activated Akt. PI3K and Akt inhibitors and expression of the constitutively active mutant GSK-3β^S9A significantly reduced the CA SC5314-stimulated IL-1β production in LDOC1-deficient cells. These results indicate that the PI3K/Akt/pGSK-3β signaling pathway contributes to LDOC1-mediated inhibition of oral microbe-induced IL-1β production, suggesting that LDOC1 may determine the pathogenic role of oral microbes in POH-associated OSCC.

A comparative study of Candida species diversity among patients with oral squamous cell carcinoma and oral potentially malignant disorders

Objectives

To determine the prevalence of Candida species by PCR–RFLP method in the saliva of patients with oral squamous cell carcinoma (OSCC), oral potentially malignant disorders (OPMD) and healthy cohorts. Unstimulated saliva was collected from patients with OSCC (n = 97), OPMD (n = 200), and healthy controls (n = 200). Candida species were isolated using the standard protocol. The isolates were identified using phenotypic and genotypic methods. The odds/risk ratio was calculated using Pearson’s Chi-square test. The significance of Candidal carriage was calculated by independent T-test.

Results

Oral Candidal carriage was 72.2%, 58% and 20.5% among patients with OSCC, OPMD, and healthy controls respectively. The oral Candidal carriage in OSCC and OPMD was highly significant (p = 0.0001). Non albicans Candida predominated over Candida albicans. Candida species were diverse among the study groups with a predominance of Candida krusei, Candida tropicalis, and Pichia anomala formerly Candida pelliculosa. P. anomala occurrence outnumbered in health. The odds/risk ratio for OSCC and OPMD were 4.25/11.87 and 3.52/6.99 respectively. A high prevalence of non albicans Candida was observed both in all the three groups (OSCC, OPMD and healthy controls). High odds and risk ratio associates Candida species to OSCC and OPMD. Candida famata may be associated with OSCC and OPMD.

The interplay of the oral microbiome and alcohol consumption in oral squamous cell carcinomas

Oral cancer (OC) is among the top twenty occurring cancers in the world, with a mortality rate of 50%. A shift to a functionally inflammatory or a 'disease state' oral microbiome composition has been observed amongst patients with premalignant disorders and OC, with evidence suggesting alcohol could be exacerbating the inflammatory influence of the oral microorganisms. Alcohol dehydrogenase (ADH, EC 1.1.1.1) converts alcohol into a known carcinogenic metabolite, acetaldehyde and while ADH levels in oral mucosa are low, several oral commensal species possess ADH and could produce genotoxic levels of acetaldehyde. With a direct association between oral microbiome status, alcohol and poor oral health status combining to induce chronic inflammation with increased acetaldehyde levels - this leads to a tumour promoting environment. This new disease state increases the production of reactive oxygen species (ROS), while impairing anti-oxidant systems thus activating the redox signalling required for the promotion and survival of tumours. This review aims to highlight the evidence linking these processes in the progression of oral cancer.