Oral candidosis in relation to oral immunity

Synergistic effects of Candida albicans and Porphyromonas gingivalis biofilms on epithelial barrier function in a 3D aspiration pneumonia model

Introduction

Polymicrobial infections involving Candida albicans and Porphyromonas gingivalis represent a significant challenge in maintaining epithelial barrier integrity. This study explores their synergistic effects on epithelial cells using an air-liquid interface (ALI) model.

Methods

Mixed-species biofilms were developed and analyzed for their impact on epithelial permeability and tight junction proteins. The effects of biofilm supernatants on IL-8 secretion and oxidative stress markers were also evaluated. The role of P. gingivalis proteases was assessed using a gingipain-null mutant (ΔKΔRAB) compared to the wild-type strain (W83). Survival experiments were conducted using Galleria mellonella larvae to examine the pathogenicity of dual-species biofilms.

Results

Mixed-species biofilms significantly increased epithelial permeability and disrupted tight junction proteins, as evidenced by reduced levels of ZO-1 and E-cadherin. These changes were accompanied by oxidative stress, characterized by decreased HO-1 expression and enhanced Bax/Bcl-xL ratios, indicating increased pro-apoptotic activity. Supernatants from dual-species biofilms demonstrated a pronounced effect on epithelial cells, modulating IL-8 secretion and exacerbating oxidative damage. C. albicans was identified as the dominant driver of pro-inflammatory responses, while P. gingivalis contributed through immune modulation and enzymatic activity, primarily via gingipains. The ΔKΔRAB mutant biofilms caused less epithelial disruption and oxidative stress compared to the wild-type, highlighting the critical role of gingipains in pathogenesis.

Discussion

Survival experiments using Galleria mellonella larvae supported these findings, highlighting the reduced survival associated with dual-species biofilms and the potential for high-dose antimicrobial therapies to mitigate this effect. These results emphasize the cooperative mechanisms of C. albicans and P. gingivalis in compromising epithelial barriers and underline the importance of combination therapies targeting both fungal and bacterial components in polymicrobial infections.

Chitosan from the base of Flammulina velutipes stipe alleviates oral Candida albicans infection via modulating Th-17 cell differentiation and Streptococcus mutans

The base of Flammulina velutipes (F. velutipes) stipe are agricultural wastes generated during the cultivation of edible fungus F. velutipes with high amount of chitin. Herein, this study firstly prepared chitosan from the base of F. velutipes stipe (FVC) and its structure was identified. It was confirmed that FVC acted as an antigenic substance to activate the immune system in vivo and in vitro, drive T cells to differentiate into Th-17 cells, and establish an effective mucosal immune barrier in the oral cavity, thus inhibited C. albicans infection; On the other hand, FVC maintained the oral flora stability and significantly reduced the abundance of Streptococcus spp., which was closely related to C. albicans infection. On this basis, the inhibitory effects of FVC on oral pathogens Streptococcus mutans and Lactobacillus casei associated with C. albicans infection were further verified, and it was demonstrated that FVC effectively interfered with the growth of pathogenic bacteria by inducing the production of intracellular ROS to damage bacterial cells. Therefore, FVC may be potentially exploited as a novel approach to the prevention and treatment of oral C. albicans infection.

Candida Variety in the Oral Cavity of Mexican Subjects with Type 2 Diabetes Mellitus and TLR2 Gene Expression

BACKGROUND

The aim was to diagnose Candida in the oral cavity of subjects with type 2 diabetes mellitus (T2DM) using a genotyping technique and compare the results with those from conventional diagnosis by Papanicolaou (Pap) staining.

METHODS

Palatal mucosa smears were performed on 18 dental care patients diagnosed with T2DM and grade I, II, and III prosthetic stomatitis who met the inclusion criteria; 18 healthy control subjects were also included in the study. Hemoglobin A1c (HbA1c) levels were determined from total blood. Using exfoliative cytology, the Pap staining technique was used to diagnose candidiasis. Exfoliative cytology was also used for molecular diagnosis; DNA was obtained for Candida genotyping, and RNA was used for gene expression studies.

RESULTS

Clinical patterns indicated that all subjects were positive for Candida; however, Pap analysis revealed only three positive subjects, whereas end-point polymerase chain reaction (PCR) analysis revealed 15 subjects with some type of Candida. The most common Candida species found were Candida guilliermondii (38.8%), Candida krusei (33.3%), Candida tropicalis, and Candida lusitaniae (22.2%). Interestingly, the coexpression of different species of Candida was found in various patients. In all patients, HbA1c levels were increased. Gene expression analysis showed a significant decrease (p ≤ 0.05) in TLR2 expression in positive subjects, whereas TLR4 expression did not differ significantly among patients.

CONCLUSIONS

The end-point PCR technique showed better sensitivity for the diagnosis of Candida when compared with the diagnosis by Pap staining. T2DM subjects showed an increased presence of C. guilliermondii that was correlated with decreased TLR2 expression.

TULA Proteins in Men, Mice, Hens, and Lice: Welcome to the Family

The two members of the UBASH3/STS/TULA protein family have been shown to critically regulate key biological functions, including immunity and hemostasis, in mammalian biological systems. Negative regulation of signaling through immune receptor tyrosine-based activation motif (ITAM)- and hemITAM-bearing receptors mediated by Syk-family protein tyrosine kinases appears to be a major molecular mechanism of the down-regulatory effect of TULA-family proteins, which possess protein tyrosine phosphatase (PTP) activity. However, these proteins are likely to carry out some PTP-independent functions as well. Whereas the effects of TULA-family proteins overlap, their characteristics and their individual contributions to cellular regulation also demonstrate clearly distinct features. Protein structure, enzymatic activity, molecular mechanisms of regulation, and biological functions of TULA-family proteins are discussed in this review. In particular, the usefulness of the comparative analysis of TULA proteins in various metazoan taxa, for identifying potential roles of TULA-family proteins outside of their functions already established in mammalian systems, is examined.

Candida albicans can foster gut dysbiosis and systemic inflammation during HIV infection

Candida albicans (C. albicans) is a ubiquitous fungal commensal component of the human microbiota, and under certain circumstances, such as during an immunocompromised state, it may initiate different types of infection. Moreover, C. albicans continuously and reciprocally interacts with the host immune system as well as with other elements of the gut microbiota, thus contributing significantly to both gut homeostasis and host immunity. People living with HIV (PLWH), including those receiving antiretroviral therapy, are characterized by a depletion of CD4 + T-cells and dysbiosis in their gut. C. albicans colonization is frequent in PLWH, causing both a high prevalence and high morbidity. Gut barrier damage and elevated levels of microbial translocation are also fairly common in this population. Herein, we take a closer look at the reciprocity among C. albicans, gut microbiota, HIV, and the host immune system, thus throwing some light on this complex interplay.

Candida albicans-enteric viral interactions-The prostaglandin E2 connection and host immune responses

The human microbiome comprises trillions of microorganisms residing within different mucosal cavities and across the body surface. The gut microbiota modulates host susceptibility to viral infections in several ways, and microbial interkingdom interactions increase viral infectivity within the gut. Candida albicans, a frequently encountered fungal species in the gut, produces highly structured biofilms and eicosanoids such as prostaglandin E₂ (PGE₂), which aid in viral protection and replication. These biofilms encompass viruses and provide a shield from antiviral drugs or the immune system. PGE₂ is a key modulator of active inflammation with the potential to regulate interferon signaling upon microbial invasion or viral infections. In this review, we raise the perspective of gut interkingdom interactions involving C. albicans and enteric viruses, with a special focus on biofilms, PGE₂, and viral replication. Ultimately, we discuss the possible implications of C. albicans-enteric virus associations on host immune responses, particularly the interferon signaling pathway.

Synergistic Efficacy of Plaque Control with Intralesional Triamcinolone Acetonide Injection on Erosive Non-Gingival Oral Lichen Planus: A Randomized Controlled Clinical Trial

This study is the first time to assess the synergistic efficacy and safety of plaque control on erosive non-gingival oral lichen planus (OLP). A randomized, controlled, clinical trial with blind evaluation was designed, and 48 OLP patients with erosive non-gingival OLP lesions were randomly assigned to the experimental group (n = 25, receiving intralesional triamcinolone acetonide injection, periodontal scaling, and oral hygiene instruction) and the control group (n = 23, only receiving intralesional triamcinolone acetonide injection) once a week for 2 weeks. Erosion size, pain level, plaque index, and community periodontal index were measured at every visit. Patients cured of erosion were followed up for 3 months to evaluate the recurrence rate. Adverse reactions were also recorded. At day 14 ± 2, the experimental group showed a higher completely healed percentage of erosion, a greater reduction of erosion size and pain level. However, no significant difference was observed in the recurrence rate. No participants had any severe adverse reactions. In conclusion, an improvement was observed in patients with plaque control, and future studies with larger sample sizes are needed to reinforce the external validity of this study.

Oral Cavity and Candida albicans: Colonisation to the Development of Infection

Candida colonisation of the oral cavity increases in immunocompromised individuals which leads to the development of oral candidiasis. In addition, host factors such as xerostomia, smoking, oral prostheses, dental caries, diabetes and cancer treatment accelerate the disease process. Candida albicans is the primary causative agent of this infection, owing to its ability to form biofilm and hyphae and to produce hydrolytic enzymes and candialysin. Although mucosal immunity is activated, from the time hyphae-associated toxin is formed by the colonising C. albicans cells, an increased number and virulence of this pathogenic organism collectively leads to infection. Prevention of the development of infection can be achieved by addressing the host physiological factors and habits. For maintenance of oral health, conventional oral hygiene products containing antimicrobial compounds, essential oils and phytochemicals can be considered, these products can maintain the low number of Candida in the oral cavity and reduce their virulence. Vulnerable patients should be educated in order to increase compliance.

Biological consequences of cancer radiotherapy in the context of oral squamous cell carcinoma

Approximately 50% of subjects with cancer have been treated with ionizing radiation (IR) either as a curative, adjuvant, neoadjuvant or as a palliative agent, at some point during the clinical course of their disease. IR kills cancer cells directly by injuring their DNA, and indirectly by inducing immunogenic cell killing mediated by cytotoxic T cells; but it can also induce harmful biological responses to non-irradiated neighbouring cells (bystander effect) and to more distant cells (abscopal effect) outside the primary tumour field of irradiation.Although IR can upregulate anti-tumour immune reactions, it can also promote an immunosuppressive tumour microenvironment. Consequently, radiotherapy by itself is seldom sufficient to generate an effective long lasting immune response that is capable to control growth of metastasis, recurrence of primary tumours and development of second primary cancers. Therefore, combining radiotherapy with the use of immunoadjuvants such as immune checkpoint inhibitors, can potentiate IR-mediated anti-tumour immune reactions, bringing about a synergic immunogenic cell killing effect.The purpose of this narrative review is to discuss some aspects of IR-induced biological responses, including factors that contributes to tumour radiosensitivity/radioresistance, immunogenic cell killing, and the abscopal effect.

Smoking increases oral mucosa susceptibility to Candida albicans infection via the Nrf2 pathway: In vitro and animal studies

Smoking and Candida albicans (C. albicans) infection are risk factors for many oral diseases. Several studies have reported a close relationship between smoking and the occurrence of C. albicans infection. However, the exact underlying mechanism of this relationship remains unclear. We established a rat infection model and a C. albicans-Leuk1 epithelial cell co-culture model with and without smoke exposure to investigate the mechanism by which smoking contributes to C. albicans infection. Oral mucosa samples from healthy individuals and patients with oral leucoplakia were also analysed according to their smoking status. Our results indicated that smoking induced oxidative stress and redox dysfunction in the oral mucosa. Smoking-induced Nrf2 negatively regulated the NLRP3 inflammasome, impaired the oral mucosal defence response and increased the oral mucosa susceptibility to C. albicans. The results suggest that the Nrf2 pathway could be involved in the pathogenesis of oral diseases by mediating an antioxidative response to cigarette smoke exposure and suppressing host immunity against C. albicans.

Quercetin protects oral mucosal keratinocytes against lipopolysaccharide-induced inflammatory toxicity by suppressing the AKT/AMPK/mTOR pathway

BACKGROUND

Cytokines can induce a chronic inflammatory response in the periodontium, leading to periodontitis. Quercetin, a naturally occuring flavonoid, has been shown to inhibit periodontitis, but how it works is poorly understood. In this study, we assessed the impact of quercetin on lipopolysaccharide (LPS)-induced inflammatory damage in oral mucosal keratinocytes (hOMK107) and explored its underlying mechanism.

METHODS

The viability and apoptosis of hOMK107 cells were measured after exposure to LPS, followed or not by quercetin. The production of IL-1β, IL-6, IL-8, TNF-ɑ, iNOS, and COX-2 was quantified by enzyme-linked immunosorbent assay (ELISA), while levels of Akt, AMPK, and mTOR and their phosphorylation were detected semi-quantitatively by western blotting.

RESULTS

Quercetin significantly improved cell viability and apoptosis by reversing LPS-induced upregulation of Bax and downregulation of Bcl-2 in hOMK107 cells. Quercetin decreased the production of IL-1β, IL-6, IL-8, TNF-ɑ, iNOS, and COX-2, as well as signal transduction via the Akt/AMPK/mTOR pathway. Inhibitors of Akt, AMPK, and mTOR strengthened the anti-apoptotic effects of quercetin, while agonists of Akt, AMPK, or mTOR or Akt overexpression weakened the anti-apoptotic effects.

CONCLUSION

These results indicate that quercetin may have a potential protective effect against the chronic inflammation-related periodontitis via suppressing Akt/AMPK/mTOR pathway.

Oral Candidosis: Pathophysiology and Best Practice for Diagnosis, Classification, and Successful Management

Oral candidosis is the most common fungal infection that frequently occurs in patients debilitated by other diseases or conditions. No candidosis happens without a cause; hence oral candidosis has been branded as a disease of the diseased. Prior research has identified oral candidosis as a mark of systemic diseases, such as hematinic deficiency, diabetes mellitus, leukopenia, HIV/AIDS, malignancies, and carbohydrate-rich diet, drugs, or immunosuppressive conditions. An array of interaction between Candida and the host is dynamic and complex. Candida exhibits multifaceted strategies for growth, proliferation, evasion of host defenses, and survival within the host to induce fungal infection. Oral candidosis presents a variety of clinical forms, including pseudomembranous candidosis, erythematous candidosis, angular cheilitis, median rhomboid glossitis, cheilocandidosis, juxtavermillion candidosis, mucocutaneous candidosis, hyperplastic candidosis, oropharyngeal candidosis, and rare suppurative candidosis. The prognosis is usually favorable, but treatment failure or recurrence is common due to either incorrect diagnosis, missing other pathology, inability to address underlying risk factors, or inaccurate prescription of antifungal agents. In immunocompromised patients, oropharyngeal candidosis can spread to the bloodstream or upper gastrointestinal tract, leading to potentially lethal systemic candidosis. This review therefore describes oral candidosis with regard to its pathophysiology and best practice for diagnosis, practical classification, and successful management.

Yeast-Host Interactions: Anadenanthera colubrina Modulates Virulence Factors of C. albicans and Inflammatory Response In Vitro

Oral candidiasis is one of the most common fungal infections in humans. Its incidence has increased widely, as well as the antifungal resistance, demanding for the search for novel antifungal therapeutic agents. Anadenanthera colubrina (Vell.) Brenan is a plant species that has been proven to possess pharmacological effects, including antifungal and anti-inflammatory activities. This study evaluated in vitro the effects of standardized A. colubrina extract on virulence factors of Candida albicans and its regulation on immune response through C. albicans-host interaction. Antifungal activity was evaluated by Broth Microdilution Method against reference Candida strains (C. albicans, C. glabrata, C. tropicalis; C. dubliniensis). Anti-biofilm effect was performed on C. albicans mature biofilm and quantified by CFU/mL/g of biofilm dry weight. Proleotlytic enzymatic activities of proteinase and phospholipase were assessed by Azocasein and Phosphatidylcholine assays, respectively. Cytotoxicity effect was determined by Cell Titer Blue Viability Assay on Human Gingival Fibroblasts. Co-cultured model was used to analyze C. albicans coexisting with HGF by Scanning Electron Microscopy and fluorescence microscopies; gene expression was assessed by RT-PCR of C. albicans enzymes (SAP-1, PLB-1) and of host inflammatory cytokines (IL-6, IL-8, IL-1β, IL-10). Cytokines secretion was analysed by Luminex. The extract presented antifungal effect with MIC<15.62 μg/ml against Candida strains. Biofilm and proteolytic activity were significant reduced at 312.4 μg/ml (20 × 15.62 μg/ml) extract concentration. Cell viability was maintained higher than 70% in concentrations up to 250 μg/ml (LD50 = 423.3 μg/ml). Co-culture microscopies demonstrated a substantial decreased in C. albicans growth and minimal toxicity against host cells. Gene expressions of SAP-1/PLB-1 were significantly down-regulated and host immune response was modulated by a significant decreased on IL-6 and IL-8 cytokines secretion. A. colubrina had antifungal activity on Candida strains, antibiofilm, and anti-proteolytic enzyme effects against C. albicans. Presented low cytotoxicity to the host cells and modulatory effects on the host immune response.

Microbial interactions and immunity response in oral Candida species

Oral candidiasis are among the most common noncommunicable diseases, related with serious local and systemic illnesses. Although these infections can occur in all kinds of patients, they are more recurrent in immunosuppressed ones such as patients with HIV, hepatitis, cancer or under long antimicrobial treatments. Candida albicans continues to be the most frequently identified Candida spp. in these disorders, but other non-C. albicans Candida are rising. Understanding the immune responses involved in oral Candida spp. infections is a key feature to a successful treatment and to the design of novel therapies. In this review, we performed a literature search in PubMed and WoS, in order to examine and analyze common oral Candida spp.-bacteria/Candida-Candida interactions and the host immunity response in oral candidiasis.

Glucose effect on Candida albicans biofilm during tissue invasion

OBJECTIVE

To evaluate, in vitro, the effect of two glucose concentrations (0.1 mM and 1.0 mM, simulating glucose concentration in saliva of healthy and diabetic individuals) on Candida albicans biofilm grown on epithelial monolayer.

MATERIAL AND METHODS

C. albicans was inoculated on epithelial monolayers supplemented with 0.1 mM, 1.0 mM or no glucose. Control groups without C. albicans were also evaluated. Tissue response was assessed through the production of Interleukin-1α, Interleukin-8, Interleukin-6, Interleukin-10 and tumor necrosis factor-α. The complex of monolayer and biofilms were evaluated by quantitative reverse transcription polymerase chain reaction for expression of E-cadherin (CDH1), Caspase-3 (CASP3), β-defensin-1 (DEFB-1) and β-defensin-3 (DEFB-3). The biofilm architecture was visualized by confocal laser scanning microscopy.

RESULTS

The production of Interleukin-1α and Interleukin-8 were increased in the presence of C. albicans (p < 0.05). Glucose did not interfere in the release of any cytokine evaluated. C. albicans downregulated transcripts for CDH1 (p < 0.05). Glucose did not induce a significant change in CDH1, CASP3, DEFB-1 and DEFB-3 messenger RNA expression. The biofilms were more structured in the presence of glucose, but no difference in the diffusion of hyphae through the epithelial cells were observed.

CONCLUSIONS

The data suggest that glucose concentration does not affect the behavior of C. albicans during tissue invasion and other mechanisms must be related to the greater susceptibility of diabetic individuals to candidiasis.

Factors Associated with Oral Candidiasis in People Living with HIV/AIDS: A Case Control Study

Background

Oral candidiasis (OC) is the most frequent opportunistic infection of the oral cavity caused by Candida species overgrowth. A wide variety of risk factor that contributes to yeast infection especially candidiasis. It might be acting as an early marker for people living with HIV/AIDS (PLWHA). There are some risk factors for PLWHA associated OC at Wangaya hospital in Denpasar, Bali, Indonesia.

Aim

To identify risk factors of OC in PLWHA at Wangaya Hospital in Denpasar, Bali, Indonesia.

Settings and Design

Case control study was conducted from March 1, 2016 and July 30, 2019, included 448 participants (207 cases and 241 controls). Consecutive recruitment was employed.

Methods

Cases were PLWHA (18 to 60 years old) with OC and controls without OC. Diagnosis of OC based on the clinical features which are the pseudomembranous candidiasis; oral thrush. An interviewer administered a structured questionnaire used to collect information on risk factors. Statistical analysis used: bivariate analysis was performed on all variables. Chi-square test with statistically significant was at a level of 0.05.

Results

The participants included 207 (46.20%) PLWHA with OC and 241 (53.80%) PLWHA who did not have OC. The majority participants, 293 (65.40%) were male. OC was associated with age [p = 0.03; OR = 0.66 (95% CI:0.45-0.95)]; sex [p = 0.002; OR = 1.88 (95% CI:1.26-2.80)]; Xerostomia [p = 0.000; OR = 4.15 (95% CI:2.76-6.23)]; smoking [p = 0.000; OR = 6.83 (95% CI: 4.46-10.44)]; alcohol consumption [p = 0.000; OR = 5.76 (95% CI: 3.74-8.83)]; antibiotic usage [p = 0.000; OR = 4.49 (95% CI: 2.93-6.90)]; CD4 count [p = 0.000; OR = 3.29 (95% CI:2.24-4.86)]; HIV clinical stage [p = 0.000; OR = 3.58 (95% CI 2.39-5.37)]. No significant association between prothesis with OC.

Conclusion

We found that age, sex, xerostomia, smoking, alcohol consumption, antibiotic usage, CD4 counts and advanced HIV Clinical stage (AIDS) were significant associated risk factors for OC in PLWHA.

Noma (cancrum oris): An unresolved global challenge

Noma (canrum oris) is a mutilating necrotizing disease of uncertain etiology, but it is accepted that it is caused primarily by a polybacterial infection with secondary ischemia. The consequent necrotizing fasciitis, myonecrosis, and osteonecrosis results in destruction of facial structures with severe functional impairment and disfigurement. It most frequently affects children, particularly in sub‐Saharan Africa, who are malnourished or debilitated by systemic conditions including but not limited to malaria, measles, and tuberculosis; and less frequently debilitated HIV‐seropositive subjects. In the vast majority of cases, in susceptible subjects, noma is preceded by necrotizing stomatitis. However, it has been reported, albeit rarely, that noma can arise without any preceding oral lesions being observed. Noma is not recurrent and is not transmissible.

Oral Fungal Microbiota: To Thrush and Beyond

The oral microbiota is complex, multikingdom, interactive, and involves extensive biofilm formation. While dominated by bacteria, Candida is a frequent member of this microbiota; however, several other potentially pathogenic fungi (among around 100 identified species) appear to reside in some individuals, including Cryptococcus, Aspergillus, and Fusarium. Oral candidiasis may manifest as a variety of disease entities in normal hosts and in the immunocompromised. These include pseudomembranous candidiasis (thrush), hyperplastic or atrophic (denture) candidiasis, linear gingival erythema, median rhomboid glossitis, and angular cheilitis. The purpose of this review is to describe the oral fungal microbiota (ie, oral mycobiota), common mouth diseases caused by its members, predisposing factors and treatment, and the potential for causing disseminated disease like their bacterial counterparts.

Establishment and Characterization of an Immortalized Porcine Oral Mucosal Epithelial Cell Line as a Cytopathogenic Model for Porcine Circovirus 2 Infection

Porcine circovirus 2 (PCV2) is a major etiological agent for porcine circovirus-associated diseases and causes enormous economic losses in domestic and overseas swine production. However, there are currently no suitable cell models to study the cytopathic effects (CPE) of PCV2 in vitro, which severely restricts the study of PCV2 pathogenesis. In the present study, we established an immortalized porcine oral mucosal epithelial cell line (hTERT-POMEC) by introducing the hTERT gene into primary porcine oral mucosal epithelial cells (POMECs) derived from a neonatal, unsuckled piglet. The hTERT-POMEC cells have a homogeneous cobblestone-like morphology and retain the basic physiological properties of primary POMECs. No chromosome abnormality and tumorigenicity transformation was observed in immortalized hTERT-POMECs. Viral infection assays demonstrated that PCV2 propagated and caused CPE in hTERT-POMECs. We conclude that the immortalized cell line hTERT-POMEC is a crucial tool for further research into the pathogenesis of PCV2.

Long-term cigarette smoking suppresses NLRP3 inflammasome activation in oral mucosal epithelium and attenuates host defense against Candida albicans in a rat model

Cigarette smoke (CS) exposure and Candida albicans (C. albicans) infection are epidemiological risk factors for oral diseases, such as oral leukoplakia (OLK). Smoking-induced inflammation and immune modulation are potentially important mechanisms in the development of diseases, although the biological mechanism of how CS exposure impacts host defenses has not been elucidated. The critical components of host defense, NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome and IL-1β, are required for normal immune function in order to efficiently control infection. This paper studies the molecular mechanism of the immune-suppressive effect of CS on the oral mucosa of animal models. Rats were exposed to intraoral CS to simulate active human smoking and/or to C. albicans for 3 months or 6 months, and their ability to control the infection of C. albicans was examined. The CS and C. albicans co-exposed rats showed early stage lesions of OLK and were more susceptible to C. albicans than those in the C. albicans-exposed group. CS caused a reduced expression of the NLRP3 inflammasome and diminished the secretion of IL-1β and IL-18 maturing by the NLRP3 inflammasome, which were stimulated by C. albicans. CS and immune suppression appear to be closely interwoven at multiple levels. This is the first animal model of active smoking through the mouth, and these data demonstrate that CS suppresses the protective immune response to C. albicans in rats through the NLRP3 inflammasome.

Recent Progress of Basic Studies of Natural Products and Their Dental Application

The present article reviews the research progress of three major polyphenols (tannins, flavonoids and lignin carbohydrate complexes), chromone (backbone structure of flavonoids) and herbal extracts. Chemical modified chromone derivatives showed highly specific toxicity against human oral squamous cell carcinoma cell lines, with much lower toxicity against human oral keratinocytes, as compared with various anticancer drugs. QSAR analysis suggests the possible correlation between their tumor-specificity and three-dimensional molecular shape. Condensed tannins in the tea extracts inactivated the glucosyltransferase enzymes, involved in the biofilm formation. Lignin-carbohydrate complexes (prepared by alkaline extraction and acid-precipitation) and crude alkaline extract of the leaves of Sasa species (SE, available as an over-the-counter drug) showed much higher anti-HIV activity, than tannins, flavonoids and Japanese traditional medicine (Kampo). Long-term treatment with SE and several Kampo medicines showed an anti-inflammatory and anti-oxidant effects in small size of clinical trials. Although the anti-periodontitis activity of synthetic angiotensin II blockers has been suggested in many papers, natural angiotensin II blockers has not yet been tested for their possible anti-periodontitis activity. There should be still many unknown substances that are useful for treating the oral diseases in the natural kingdom.

Vitamin D Deficiency as It Relates to Oral Immunity and Chronic Periodontitis

The biologically active form of vitamin D, 1,25 dihydroxyvitamin D (1,25(OH)2D) and its receptor, the vitamin D receptor (VDR), play roles in maintaining oral immunity and the integrity of the periodontium. Results of observational cross-sectional clinical studies investigating the association between vitamin D serum level and the incidence and severity of chronic periodontitis indicate that, perhaps owing to the immunomodulatory, anti-inflammatory, and antibacterial properties of 1,25(OH)2 D/VDR signalling, a sufficient serum level of vitamin D is necessary for the maintenance of periodontal health. In cases of established chronic periodontitis, vitamin D supplementation is associated with reduction in the severity of periodontitis. As cross-sectional studies provide only weak evidence for any causal association and therefore are of questionable value, either longitudinal cohort studies, case controlled studies, or randomized control trials are needed to determine whether or not deficiency of vitamin D is a risk factor for chronic periodontitis, and whether or not vitamin D supplementation adjunctive to standard periodontal treatment is in any way beneficial. In this article, we discuss the relationship between vitamin D, oral immunity and periodontal disease and review the rationale for using vitamin D supplementation to help maintain periodontal health and as an adjunct to standard periodontal treatment.

Search of Neuroprotective Polyphenols Using the "Overlay" Isolation Method

Previous studies of the neuroprotective activity of polyphenols have used ununiform culture systems, making it difficult to compare their neuroprotective potency. We have established a new and simple method for preparing differentiated PC12 cells by removing the toxic coating step. Cells were induced to differentiate with the nerve growth factor (NGF) in a serum-free medium, without a medium change, but with a one-time overlay supplementation of NGF. The optimal inoculation density of the cells was 6–12 × 10³ cells/cm², and the presence of serum inhibited the differentiation. Neuroprotective activity could be quantified by the specific index (SI) value, that is, the ratio of the 50% cytotoxic concentration to the 50% effective concentration. Alkaline extract from the leaves of Sasa senanensis Rehder (SE), having had hormetic growth stimulation, showed the highest SI value, followed by epigallocatechin gallate. The SI value of curcumin and resveratrol was much lower. This simple overly method, that can prepare massive differentiated neuronal cells, may be applicable for the study of the differentiation-associated changes in intracellular metabolites, and the interaction between neuronal cells and physiological factors.

Prevalence of two Entamoeba gingivalis ST1 and ST2-kamaktli subtypes in the human oral cavity under various conditions

Advances in molecular biology have facilitated analyses of the oral microbiome; however, the parasites role is poorly understood. Periodontal disease is a multifactorial process involving complex interactions among microorganisms, the host, and environmental factors. At present, the precise composition of the mouth parasites microbiota is unclear. Two protozoan species have been detected in the oral microbiota: Trichomonas tenax and Entamoeba gingivalis, and a new variant, E. gingivalis-ST2-kamaktli, was recently identified by us. In this study, both E. gingivalis and the new E. gingivalis-ST2-kamaktli variant were detected in the oral cavities of people with healthy periodontium, individuals undergoing orthodontic treatment, and patients with periodontal disease. In the group with healthy periodontium, the prevalence of E. gingivalis-ST1 was 48.6% and that of E. gingivalis-ST2-kamaktli 29.5%, with a combined prevalence of 54.3%. In patients undergoing orthodontics treatment, 81.2% carried both amoebas, with 47.5% having E. gingivalis-ST1 and 73.8% E. gingivalis-ST2-kamaktli. In people with periodontal disease, the prevalence of E. gingivalis-ST1 was 57.8%, and that of E. gingivalis-ST2-kamaktli 50.0%, with a combined prevalence of 73.5%; hence, E. gingivalis-ST1 and E gingivalis-ST2-kamaktli were detected in all three groups. The question arises, what are E. gingivalis-ST1 and E. gingivalis-ST2-kamaktli doing in the oral cavity? Although, the answer remains unclear, our results suggest that each amoeba subtype is genetically distinct, and they exhibit different patterns of infectious behavior. We hypothesize that E. gingivalis-ST1 and E. gingivalis-ST2-kamaktli may represent separate species. Our data contribute to better understanding of the roles of E. gingivalis-ST1 and E. gingivalis-ST2-kamaktli in the oral microbiota.

Differences in interleukin-1β release-inducing activity of Candida albicans toward dendritic cells and macrophages

OBJECTIVE

The purpose of this study is to elucidate differences in the mechanism of the IL-1β release-inducing activity of Candida albicans toward dendritic cells and macrophages because IL-1β is one of the proinflammatory cytokines which is crucial in host defense against candidiasis.

DESIGN

Two C. albicans strains were used in this study. One strain is uridine-auxotrophic (CAI4) that needs uridine to grow and form hyphae, and another is a strain without any specific auxotrophy (pACT1-GFP), which forms hyphae naturally by culturing with serum components. Murine macrophage and dendritic cell lines were primed with LPS and then stimulated with C. albicans CAI4 or pACT1-GFP.

RESULTS

Both strains of C. albicans induced IL-1β release from dendritic cells, and C. albicans pACT1-GFP induced IL-1β release but CAI4 induced little amounts in macrophages. These differences were suggested to be due to the difference in the amount of extracellular ATP released in the cell culture supernatants induced by C. albicans CAI4 or pACT1-GFP. For induction of IL-1β release from both macrophages and dendritic cells by C. albicans, direct contacts of the microbes with cells were required. In addition, macrophages required morphological change of C. albicans from yeast to hyphae for induction of IL-1β release, whereas dendritic cells did not require it. Dead C. albicans could induce IL-1β release from dendritic cells, but could not from macrophages.

CONCLUSIONS

There are different mechanisms by which C. albicans induces IL-1β release from dendritic cells and macrophages.

Oral candidiasis among African human immunodeficiency virus-infected individuals: 10 years of systematic review and meta-analysis from sub-Saharan Africa

Oral candidiasis (OC) is the most common opportunistic fungal infection among immunocompromised individuals. This systematic review and meta-analysis reports on the contribution of non-albicans Candida species in causing OC among human immunodeficiency virus (HIV)-infected individuals in sub-Saharan Africa between 2005 and 2015. Thirteen original research articles on oral Candida infection/colonization among HIV-infected African populations were reviewed. The prevalence of OC ranged from 7.6% to 75.3%. Pseudomembranous candidiasis was found to range from 12.1% to 66.7%. The prevalence of non-albicans Candida species causing OC was 33.5% [95% confidence interval (CI) 30.9–36.39%]. Of 458 non-albicans Candida species detected, C. glabrata (23.8%; 109/458) was the most common, followed by C. tropicalis (22%; 101/458) and C. krusei (10.7%; 49/458). The overall fluconazole resistance was 39.3% (95% CI 34.4–44.1%). Candida albicans was significantly more resistant than non-albicans Candida species to fluconazole (44.7% vs 21.9%; p < 0.001). One-quarter of the cases of OC among HIV-infected individuals in sub-Saharan Africa were due to non-albicans Candida species. Candida albicans isolates were more resistant than the non-albicans Candida species to fluconazole and voriconazole. Strengthening the capacity for fungal diagnosis and antifungal susceptibility testing in sub-Saharan Africa is mandatory in order to track the azole resistance trend.

The in vivo T helper type 17 and regulatory T cell immune responses to Aggregatibacter actinomycetemcomitans

The periodontal pathogen Aggregatibacter actinomycetemcomitans is known to elicit a systemic immune response in the infected host, and occasionally causes non-oral infections. Detailed information on its immunopathological responses and the involvement of bacterial virulence factors remains to be elucidated. The aim of this study was to assess the systemic immune response to A. actinomycetemcomitans oral infection. We used an animal model that simulates systemic dissemination of the bacteria by injecting live wild-type (WT) D7S-1 and a double knockout mutant of leukotoxin and cytolethal distending toxin (ΔltxΔcdt) A. actinomycetemcomitans strains in rat oral mucosa. Draining lymph nodes were examined for regulatory T (Treg) and T helper type 17 (Th17) cell subsets and their associated mediators. An increase in the proportion of Th17 cells and a decrease in Treg cells over the experimental period of 3 weeks were similarly observed for rats challenged with WT and ΔltxΔcdt. Significant upregulation and downregulation of proinflammatory cytokines in the Th17 gene pathway was noted, as well as several qualitative differences between WT and ΔltxΔcdt. Furthermore, we observed differential fold regulation in key genes associated with a proinflammatory response in ΔltxΔcdt-inoculated rats relative to D7S-1 group. This suggests that although the knockout of these two virulence factors (ΔltxΔcdt) may suppress certain proinflammatory genes, it causes similar over-expression of other genes compared with D7S-1, indicating a common factor that still remains in the pathogenicity of A. actinomycetemcomitans.

Review: allergic contact stomatitis

Allergic contact stomatitis (ACS) is an oral mucosal immunoinflammatory disorder variably characterized clinically by erythematous plaques, vesiculation, ulceration, and/or hyperkeratosis and by pain, burning sensation, or itchiness. ACS is brought about by a T cell-mediated, delayed hypersensitivity immune reaction generated by a second or subsequent contact exposure of an allergen with the oral mucosa, in a genetically susceptible, sensitized subject. Lichenoid contact reaction is a variant of ACS brought about by direct contact with the oral mucosa of certain metals in dental restorations. The features of ACS are neither clinically nor histopathologically specific, so the diagnosis is usually presumptive and can only be confirmed by resolution of the inflammation after withdrawal or removal of the suspected causative allergen. When ACS is suspected but an allergen cannot be identified, patch testing is necessary. In persistent cases, topical corticosteroids are the treatment of choice, but for severe and extensive lesions, systemic corticosteroid and systemic antihistamines may be indicated. In this short review, we highlight the clinical, immunologic, and histopathological features of ACS, and provide some guidelines for diagnosis and management.

Reduced CX3CL1 Secretion Contributes to the Susceptibility of Oral Leukoplakia-Associated Fibroblasts to Candida albicans

Candida leukoplakia (OLK) is a kind of oral leukoplakia combined with chronic candidal infection, which plays an important role in the malignant transformation of OLK. However, little is known about the etiology, including susceptibility of leukoplakia to candidal adhesion, invasion and infection. Some antimicrobial peptides secreted by oral epithelial cells or fibroblasts potentially have antifungal activities against Candida albicans (C. albicans). In this study, we established three co-culture models to simulate different C. albicans-fibroblasts interactions during progression of candida leukoplakia. The susceptibility of oral leukoplakia-associated fibroblasts (LKAFs) to C. albicans and its underlying mechanism were determined. Samples of 14 LKAFs and 10 normal fibroblasts (NFs) were collected. The co-culture models showed that LKAFs had promoted the adhesion, invasion, and survival of C. albicans compared with NFs. CX3CL1, a chemokine with antifungal activity, was less abundant in LKAFs than NFs. Overexpression of CX3CL1 via transfection in LKAFs could partly restore the resistance to C. albicans. We also showed that inhibition of ERK could suppress CX3CL1 secretion. While phosphor-ERK was inhibited in LKAFs compared with NFs. Besides, the mRNA expression of a shedding enzyme for CX3CL1, disintegrin and metalloproteinase domain (ADAM) 17 was decreased in LKAFs than NFs. In conclusion, LKAFs produced and secreted less CX3CL1 by inhibiting the ERK signaling pathway, thereby contributing to impaired cell resistance to C. albicans.

Innate immune cell response upon Candida albicans infection

Candida albicans is a polymorphic fungus which is the predominant cause of superficial and deep tissue fungal infections. This microorganism has developed efficient strategies to invade the host and evade host defense systems. However, the host immune system will be prepared for defense against the microbe by recognition of receptors, activation of signal transduction pathways and cooperation of immune cells. As a consequence, C. albicans could either be eliminated by immune cells rapidly or disseminate hematogenously, leading to life-threatening systemic infections. The interplay between Candida albicans and the host is complex, requiring recognition of the invaded pathogens, activation of intricate pathways and collaboration of various immune cells. In this review, we will focus on the effects of innate immunity that emphasize the first line protection of host defense against invaded C. albicans including the basis of receptor-mediated recognition and the mechanisms of cell-mediated immunity.

Herpes Simplex Virus (HSV) Modulation of Staphylococcus aureus and Candida albicans Initiation of HeLa 299 Cell-Associated Biofilm

Although herpes simplex virus type-1 (HSV-1), and type-2 (HSV-2), Staphylococcus aureus and Candida albicans co-habit the oral and genital mucosa, their interaction is poorly understood. We determined the effect HSV has on bacterial and/or fungal adherence, the initial step in biofilm formation. HeLa229 cells were infected with HSV-1 (KOS) gL86 or HSV-2 (KOS) 333gJ⁻ at a multiplicity of infection (MOI) of 50 and 10. S. aureus (ATCC 25923) and/or C. albicans (yeast forms or germ tube forms) were co-incubated for 30 min (37 °C; 5 % CO₂; 5:1 organism: HeLa cell ratio; n = 16) with virus-infected HeLa cells or uninfected HeLa cell controls. Post-incubation, the monolayers were washed (3x; PBS), lysed (RIPA), and the lysate plated onto Fungisel and/or mannitol salts agar for standard colony count. The level of HeLa-associated S. aureus was significantly decreased (P < 0.05) for both HSV-1- and HSV-2-infected cells, as compared to virus-free HeLa cell controls (38 and 59 % of control, respectively). In contrast, HSV-1 and HSV-2 significantly (P < 0.05) enhanced HeLa cell association of C. albicans yeast forms and germ tube approximately two-fold, respectively. The effect of S. aureus on germ tube and yeast form adherence to HSV-1- and HSV-2-infected cells was specific for the Candida phenotype tested. Our study suggests that HSV, while antagonist towards S. aureus adherence enhances Candida adherence. Furthermore, the combination of the three pathogens results in S. aureus adherence that is either unaffected, or partially restored depending on both the herpes viral species and the fungal phenotype present.

Defective IL-17- and IL-22-dependent mucosal host response to Candida albicans determines susceptibility to oral candidiasis in mice expressing the HIV-1 transgene

BACKGROUND

The tissue-signaling cytokines IL-17 and IL-22 are critical to host defense against oral Candida albicans infection, by their induction of oral antimicrobial peptide expression and recruitment of neutrophils. Mucosal Th17 cells which produce these cytokines are preferentially depleted in HIV-infected patients. Here, we tested the hypothesis that defective IL-17- and IL-22-dependent host responses to C. albicans determine the phenotype of susceptibility to oropharyngeal candidiasis (OPC) in transgenic (Tg) mice expressing HIV-1.

RESULTS

Naïve CD4+ T-cells and the differentiated Th1, Th2, Th17, Th1Th17 and Treg lineages were all profoundly depleted in cervical lymph nodes (CLNs) of these Tg mice. However, naive CD4+ cells from Tg mice maintained the capacity to differentiate into these lineages in response to polarizing cytokines in vitro. Expression of Il17, Il22, S100a8 and Ccl20 was enhanced in oral mucosal tissue of non-Tg, but not of Tg mice, after oral infection with C. albicans. Treatment of infected Tg mice with the combination of IL-17 and IL-22, but not IL-17 or Il-22 alone, significantly reduced oral burdens of C. albicans and abundance of Candida hyphae in the epithelium of tongues of infected Tg mice, and restored the ability of the Tg mice to up-regulate expression of S100a8 and Ccl20 in response to C. albicans infection.

CONCLUSIONS

These findings demonstrate that defective IL-17- and IL-22-dependent induction of innate mucosal immunity to C. albicans is central to the phenotype of susceptibility to OPC in these HIV transgenic mice.