Effect of HIV/HAART and Other Clinical Variables on the Oral Mycobiome Using Multivariate Analyses

Association between virus infection and periodontitis: Evidence from the National Health and Nutrition Examination Survey 2009-2014

Periodontitis is a cumulative inflammatory disease associated with multiple health conditions and various systemic diseases. As a common disease, virus infection along with its consequences has become a serious health burden. The study aims to evaluate the relationship between common viruses including hepatitis virus, human immunodeficiency virus (HIV), herpes simplex virus (HSV), human papillomavirus (HPV), and periodontitis. The data from the US National Health and Nutrition Examination Survey (NHANES) 2009-2014 was adopted and screened through, including 10 714 participants. Generalized linear regression was conducted to verify the relationships between the virus infections and periodontitis. Moreover, we also performed analyses in age and gender subgroups. The results suggested that the infection of HCV, HSV-1, and HSV-2 was significantly associated with the prevalence of periodontitis (odds ratio [OR] 1.46, 95% confidence interval [CI] 1.26-1.70; OR 1.09, 95% CI 1.05-1.13; OR 1.06, 95% CI 1.01 - 1.11, respectively) and risk of developing moderate or severe periodontitis (OR 1.51, 95% CI 1.29-1.77; OR 1.08, 95% CI 1.04-1.12; OR 1.05, 95% CI 1.01-1.10, respectively) after adjusting all relevant co-factors. Subgroup analyses revealed a steady association between periodontitis and hepatitis C virus (HCV) or HSV-1 infection, while the relationship between HSV-2 and HPV infection can also be found in some subgroups. The presence of HCV and HSV infection was found to be significantly associated with the prevalence of periodontitis, including moderate or severe cases. Moreover, the association of periodontitis and HPV infection can also be observed in people < 35 years.

Candida species in periodontitis: A new villain or a new target?

OBJECTIVES

Recent research indicated that fungi might have a role in periodontitis alongside traditional periodontal pathogens. This state-of-the-art narrative review explores current concepts on the involvement of Candida species in periodontitis, and suggests the potential for ecological management of this disease.

DATA, SOURCES AND STUDY SELECTION

A literature search was conducted for a narrative review on Web of Science, PubMed, Medline and Scopus about periodontitis associated with Candida species. Published articles, including case reports, case series, observational and interventional clinical trials, and critical appraisals of the literature were retrieved and reviewed.

CONCLUSIONS

Several factors predispose individuals to periodontitis associated with Candida species. These include systemic diseases that lead to immunosuppression and oral environment changes such as cigarette smoking. While a consistent significant increase in the detection rate of Candida species in patients with periodontitis has not been universally observed, there is evidence linking Candida species to the severity of periodontitis and their potential to worsen the condition. Candida species may participate in the development of periodontitis in various ways, including cross-kingdom interactions with periodontal pathogens, changes in the local or systemic environment favoring the virulence of Candida species, and interactions between Candida-bacteria and host immunity.

CLINICAL SIGNIFICANCE

Mechanical plaque control is the most common treatment for periodontitis, but its effectiveness may be limited, particularly when dealing with systemic risk factors. Understanding the specific role of Candida in periodontitis illuminates innovative approaches for managing the ecological balance in periodontal health.

Candida albicans natural diversity: a resource to dissect fungal commensalism and pathogenesis

Candida albicans is a ubiquitous fungus of humans. It is not only a component of the oral and intestinal microbiota of most healthy adults but also a major cause of mucosal disorders and life-threatening disseminated infections. Until recently, research on the biology and pathogenesis of the fungus was largely based on a single clinical isolate. We review investigations that have started to dissect a diverse set of C. albicans strains. Using different approaches to leverage the species' phenotypic and/or genetic diversity, these studies illuminate the wide range of interactions between fungus and host. While connecting genetic variants to phenotypes of interest remains challenging, research on C. albicans' natural diversity is central to understand fungal commensalism and pathogenesis.

Fungi and bacteria occupy distinct spatial niches within carious dentin

The role of bacteria in the etiology of dental caries is long established, while the role of fungi has only recently gained more attention. The microbial invasion of dentin in advanced caries especially merits additional research. We evaluated the fungal and bacterial community composition and spatial distribution within carious dentin. Amplicon 16S rRNA gene sequencing together with quantitative PCR was used to profile bacterial and fungal species in caries-free children (n = 43) and 4 stages of caries progression from children with severe early childhood caries (n = 32). Additionally, healthy (n = 10) and carious (n = 10) primary teeth were decalcified, sectioned, and stained with Grocott's methenamine silver, periodic acid Schiff (PAS) and calcofluor white (CW) for fungi. Immunolocalization was also performed using antibodies against fungal β-D-glucan, gram-positive bacterial lipoteichoic acid, gram-negative endotoxin, Streptococcus mutans, and Candida albicans. We also performed field emission scanning electron microscopy (FESEM) to visualize fungi and bacteria within carious dentinal tubules. Bacterial communities observed included a high abundance of S. mutans and the Veillonella parvula group, as expected. There was a higher ratio of fungi to bacteria in dentin-involved lesions compared to less severe lesions with frequent preponderance of C. albicans, C. dubliniensis, and in one case C. tropicalis. Grocott's silver, PAS, CW and immunohistochemistry (IHC) demonstrated the presence of fungi within carious dentinal tubules. Multiplex IHC revealed that fungi, gram-negative, and gram-positive bacteria primarily occupied separate dentinal tubules, with rare instances of colocalization. Similar findings were observed with multiplex immunofluorescence using anti-S. mutans and anti-C. albicans antibodies. Electron microscopy showed monomorphic bacterial and fungal biofilms within distinct dentin tubules. We demonstrate a previously unrecognized phenomenon in which fungi and bacteria occupy distinct spatial niches within carious dentin and seldom co-colonize. The potential significance of this phenomenon in caries progression warrants further exploration.

Human immunodeficiency virus and oral microbiota: mutual influence on the establishment of a viral gingival reservoir in individuals under antiretroviral therapy

The role of the oral microbiota in the overall health and in systemic diseases has gained more importance in the recent years, mainly due to the systemic effects that are mediated by the chronic inflammation caused by oral diseases, such as periodontitis, through the microbial communities of the mouth. The chronic infection by the human immunodeficiency virus (HIV) interacts at the tissue level (e.g. gut, genital tract, brain) to create reservoirs; the modulation of the gut microbiota by HIV infection is a good example of these interactions. The purpose of the present review is to assess the state of knowledge on the oral microbiota (microbiome, mycobiome and virome) of HIV-infected patients in comparison to that of HIV-negative individuals and to discuss the reciprocal influence of HIV infection and oral microbiota in patients with periodontitis on the potential establishment of a viral gingival reservoir. The influence of different clinical and biological parameters are reviewed including age, immune and viral status, potent antiretroviral therapies, smoking, infection of the airway and viral coinfections, all factors that can modulate the oral microbiota during HIV infection. The analysis of the literature proposed in this review indicates that the comparisons of the available studies are difficult due to their great heterogeneity. However, some important findings emerge: (i) the oral microbiota is less influenced than that of the gut during HIV infection, although some recurrent changes in the microbiome are identified in many studies; (ii) severe immunosuppression is correlated with altered microbiota and potent antiretroviral therapies correct partially these modifications; (iii) periodontitis constitutes a major factor of dysbiosis, which is exacerbated in HIV-infected patients; its pathogenesis can be described as a reciprocal reinforcement of the two conditions, where the local dysbiosis present in the periodontal pocket leads to inflammation, bacterial translocation and destruction of the supporting tissues, which in turn enhances an inflammatory environment that perpetuates the periodontitis cycle. With the objective of curing viral reservoirs of HIV-infected patients in the future years, it appears important to develop further researches aimed at defining whether the inflamed gingiva can serve of viral reservoir in HIV-infected patients with periodontitis.

RFX transcription factor in the human-associated yeast Candida albicans regulates adhesion to oral epithelium

Adhesion to mucosal surfaces is a critical step in many bacterial and fungal infections. Here, using a mouse model of oral infection by the human fungal pathobiont Candida albicans, we report the identification of a novel regulator of C. albicans adhesion to the oral mucosa. The regulator is a member of the regulatory factor X (RFX) family of transcription factors, which control cellular processes ranging from genome integrity in model yeasts to tissue differentiation in vertebrates. Mice infected with the C. albicans rfx1 deletion mutant displayed increased fungal burden in tongues compared to animals infected with the reference strain. High-resolution imaging revealed RFX1 transcripts being expressed by C. albicans cells during infection. Concomitant with the increase in fungal burden, the rfx1 mutant elicited an enhanced innate immune response. Transcriptome analyses uncovered HWP1, a gene encoding an adhesion protein that mediates covalent attachment to buccal cells, as a major RFX1-regulated locus. Consistent with this result, we establish that C. albicans adhesion to oral cells is modulated by RFX1 in an HWP1-dependent manner. Our findings expand the repertoire of biological processes controlled by the RFX family and illustrate a mechanism whereby C. albicans can adjust adhesion to the oral epithelium.

Supragingival mycobiome of HIV-exposed-but-uninfected children reflects a stronger correlation with caries-free-associated taxa compared to HIV-infected or uninfected children

IMPORTANCE

Globally, caries is among the most frequent chronic childhood disease, and the fungal component of the microbial community responsible is poorly studied despite evidence that fungi contribute to increased acid production exacerbating enamel demineralization. HIV infection is another global health crisis. Perinatal HIV exposure with infection are caries risk factors; however, the caries experience in the context of perinatal HIV exposure without infection is less clear. Using high-throughput amplicon sequencing, we find taxonomic differences that become pronounced during late-stage caries. Notably, we show a stronger correlation with health-associated taxa for HIV-exposed-but-uninfected children when compared to unexposed and uninfected children. This aligns with a lower incidence of caries in primary teeth at age 6 or less for exposed yet uninfected children. Ultimately, these findings could contribute to improved risk assessment, intervention, and prevention strategies such as biofilm disruption and the informed design of pro-, pre-, and synbiotic oral therapies.

Current oral hygiene and recreational behavioral trends in HIV disease

OBJECTIVE

HIV disease is evolving with more HIV+ persons experiencing a high quality of life with well-controlled viremia. We recently enrolled a large cohort of HIV+ and clinically relevant HIV- persons for oral microbiome analyses that included a questionnaire related to oral hygiene and recreational behaviors. Here, the questionnaire responses were analyzed for behavioral trends within the cohort, together with trends over time by comparison to a previous geographically centered HIV+ cohort.

METHODS

Data were collected by questionnaire at baseline visits as cross-sectional assessments. Multivariable analyses were conducted for associations of HIV status as well as age, race, and sex, on oral hygiene/recreational behaviors.

RESULTS

HIV+ subjects had reduced brushing frequency, but increased incidence of past cleanings and frequency of dry mouth, compared to the HIV- subjects. Within the entire cohort, positive associations were identified between age and several oral hygiene practices, and between age, race, and sex for several recreational behaviors. In comparison to the historical cohort, the contemporary HIV+ cohort participated in fewer high-risk behaviors, but with similar trends for smoking and oral hygiene practices.

CONCLUSION

HIV status had little association with oral hygiene and recreational behaviors despite several differences in age, race, and sex. Behavioral trends over time support a higher quality of life in people currently living with HIV.

Independent Effects of HIV and Antiretroviral Therapy on the Oral Microbiome Identified by Multivariate Analyses

The oral microbiome is an important predictor of health and disease. We recently reported significant yet modest effects of HIV under highly active antiretroviral therapy (ART) on the oral microbiome (bacterial and fungal) in a large cohort of HIV-positive (HIV+) and matched HIV-negative (HIV-) individuals. As it was unclear whether ART added to or masked further effects of HIV on the oral microbiome, the present study aimed to analyze the effects of HIV and ART independently, which also included HIV- subjects on preexposure prophylaxis (PrEP) therapy. Cross-sectional analyses of the effect of HIV devoid of ART (HIV+ ART- versus matched HIV- subjects) showed a significant effect on both the bacteriome and mycobiome (P < 0.024) after controlling for other clinical variables (permutational multivariate analysis of variance [PERMANOVA] of Bray-Curtis dissimilarity). Cross-sectional analyses evaluating the effects of ART (HIV+ ART+ versus HIV+ ART- subjects) revealed a significant effect on the mycobiome (P < 0.007) but not the bacteriome. In parallel longitudinal analyses, ART (before versus after the initiation of ART) had a significant effect on the bacteriome, but not the mycobiome, of HIV+ and HIV- PrEP subjects (P < 0.005 and P < 0.016, respectively). These analyses also revealed significant differences in the oral microbiome and several clinical variables between HIV- PrEP subjects (pre-PrEP) and the HIV-matched HIV- group (P < 0.001). At the species level, a small number of differences in both bacterial and fungal taxa were identified within the effects of HIV and/or ART. We conclude that the effects of HIV and ART on the oral microbiome are similar to those of the clinical variables but collectively are modest overall. IMPORTANCE The oral microbiome can be an important predictor of health and disease. For persons living with HIV (PLWH), HIV and highly active antiretroviral therapy (ART) may have a significant influence on their oral microbiome. We previously reported a significant effect of HIV with ART on both the bacteriome and mycobiome. It was unclear whether ART added to or masked further effects of HIV on the oral microbiome. Hence, it was important to evaluate the effects of HIV and ART independently. For this, multivariate cross-sectional and longitudinal oral microbiome analyses (bacteriome and mycobiome) were conducted within the cohort, including HIV+ ART+ subjects and HIV+ and HIV- (preexposure prophylaxis [PrEP]) subjects before and after the initiation of ART. While we report independent significant effects of HIV and ART on the oral microbiome, we conclude that their influence is similar to that of the clinical variables but collectively modest overall.

Polyamine metabolism impacts T cell dysfunction in the oral mucosa of people living with HIV

Metabolic changes in immune cells contribute to both physiological and pathophysiological outcomes of immune reactions. Here, by comparing protein expression, transcriptome, and salivary metabolome profiles of uninfected and HIV+ individuals, we found perturbations of polyamine metabolism in the oral mucosa of HIV+ patients. Mechanistic studies using an in vitro human tonsil organoid infection model revealed that HIV infection of T cells also resulted in increased polyamine synthesis, which was dependent on the activities of caspase-1, IL-1β, and ornithine decarboxylase-1. HIV-1 also led to a heightened expression of polyamine synthesis intermediates including ornithine decarboxylase-1 as well as an elevated dysfunctional regulatory T cell (T_regDys)/T helper 17 (Th17) cell ratios. Blockade of caspase-1 and polyamine synthesis intermediates reversed the T_regDys phenotype showing the direct role of polyamine pathway in altering T cell functions during HIV-1 infection. Lastly, oral mucosal T_regDys/Th17 ratios and CD4 hyperactivation positively correlated with salivary putrescine levels, which were found to be elevated in the saliva of HIV+ patients. Thus, by revealing the role of aberrantly increased polyamine synthesis during HIV infection, our study unveils a mechanism by which chronic viral infections could drive distinct T cell effector programs and T_reg dysfunction.

Mapping the human oral and gut fungal microbiota in patients with metabolic dysfunction-associated fatty liver disease

Metabolic dysfunction-associated fatty liver disease (MAFLD) is a phenotype of liver diseases associated with metabolic syndrome. The pathogenesis MAFLD remains unclear. The liver maintains is located near the intestine and is physiologically interdependent with the intestine via metabolic exchange and microbial transmission, underpinning the recently proposed "oral-gut-liver axis" concept. However, little is known about the roles of commensal fungi in the disease development. This study aimed to characterize the alterations of oral and gut mycobiota and their roles in MAFLD. Twenty-one MAFLD participants and 20 healthy controls were enrolled. Metagenomics analyses of saliva, supragingival plaques, and feces revealed significant alterations in the gut fungal composition of MAFLD patients. Although no statistical difference was evident in the oral mycobiome diversity within MAFLD and healthy group, significantly decreased diversities were observed in fecal samples of MAFLD patients. The relative abundance of one salivary species, five supragingival species, and seven fecal species was significantly altered in MAFLD patients. Twenty-two salivary, 23 supragingival, and 22 fecal species were associated with clinical parameters. Concerning the different functions of fungal species, pathways involved in metabolic pathways, biosynthesis of secondary metabolites, microbial metabolism in diverse environments, and carbon metabolism were abundant both in the oral and gut mycobiomes. Moreover, different fungal contributions in core functions were observed between MAFLD patients and the healthy controls, especially in the supragingival plaque and fecal samples. Finally, correlation analysis between oral/gut mycobiome and clinical parameters identified correlations of certain fungal species in both oral and gut niches. Particularly, Mucor ambiguus, which was abundant both in saliva and feces, was positively correlated with body mass index, total cholesterol, low-density lipoprotein, alanine aminotransferase, and aspartate aminotransferase, providing evidence of a possible "oral-gut-liver" axis. The findings illustrate the potential correlation between core mycobiome and the development of MAFLD and could propose potential therapeutic strategies.

Oral microbiota in patients with oropharyngeal cancer with an emphasis on <i>Candida</i> spp

Introduction. Interactions between the 2 microbiota components – bacteria and fungi – are of interest as diagnostic and prognostic markers in selection of treatment tactics for oncological patients.

Aim. To study microbiota of the oral cavity in patients with primary squamous cell carcinoma of the oropharyngeal area before and after surgical intervention to find biomarkers for rational selection of antifungal drugs.

Materials and methods. At the Surgical Department of Head and Neck Tumors of the N. N. Blokhin National Research Center of Oncology, three-component study was performed: investigations of spectrum of Candida spp. isolates, Candida spp. strains’ resistance to antifungals, and oral washes in primary patients before and after surgery. mALDI-Tof microflex LT (Biotyper, Bruker Daltonics, germany) was used for strain identification; Sensititre Yeast ONE, YO10 (Trek Diagnostic System, united kingdom) plates were used for determination of minimal inhibiting concentrations of anti fungals. values of minimal inhibiting concentrations were evaluated based on the European Committee on Antimicrobial Susceptibility Testing (EuCAST) criteria (version 10.0).

Results. four-year observation of patients at the surgical department of head and neck tumors of the N. N. Blokhin National Research Center of Oncology showed that the most common species of Candida is C. albicans (73.5 % of cases). Candida spp. resistance to antifungals was detected only for fluconazole (9.3 % of cases) and micafungin (8.0 % of cases), mostly among C. albicans strains. In 31.8 % of primary patients, oral washes prior to surgery showed growth of Candida spp. (probably, tissue colonization). After surgical intervention, Candida spp. growth was detected in 36.4 % of cases, only 1 of which was diagnosed as invasive mycosis. In 54.5 % of cases before and in 72.7 % of cases after surgery, gram-negative rods were detected. After surgical intervention, percentage of enterobacteria and non-fermenters significantly increased: 59.1 % versus 27.3 % (p <0.05) and 63.6 % versus 27.3 % (p <0.02), respectively. prior to surgery, non-fermenting gram-negative bacteria were represented only by P. aeruginosa; after surgery, the spectrum of non-fermenting gram-negative bacteria became wider but percentage of P. aeruginosa remained high: 71.4 %. ERG11 gene was identified only in 1 strain: C. albicans. FKS1 gene also was identified only in 1 strain: C. inconspicua. virulence factor genes were detected in 57.1 % of strains.

Conclusion. Surgical intervention is associated with changes in bacterial microbiota but not fugal microbiota. presence of virulence factor genes and resistance genes in Candida spp. strains should be considered a biomarker allowing to differentiate between colonization and candida infection and can be used for rational selection of antifungal drugs in prevention and treatment of invasive candidiasis, especially in the absence of criteria for interpretation of measured minimal inhibiting concentrations of antifungals.

Neglected mycobiome in HIV infection: Alterations, common fungal diseases and antifungal immunity

Human immunodeficiency virus (HIV) infection might have effects on both the human bacteriome and mycobiome. Although many studies have focused on alteration of the bacteriome in HIV infection, only a handful of studies have also characterized the composition of the mycobiome in HIV-infected individuals. Studies have shown that compromised immunity in HIV infection might contribute to the development of opportunistic fungal infections. Despite effective antiretroviral therapy (ART), opportunistic fungal infections continue to be a major cause of HIV-related mortality. Human immune responses are known to play a critical role in controlling fungal infections. However, the effect of HIV infection on innate and adaptive antifungal immunity remains unclear. Here, we review recent advances in understanding of the fungal microbiota composition and common fungal diseases in the setting of HIV. Moreover, we discuss innate and adaptive antifungal immunity in HIV infection.

Age-specific associations with dental caries in HIV-infected, exposed but uninfected and HIV-unexposed uninfected children in Nigeria

Background

HIV infection and its management confer a substantial health burden to affected individuals and have been associated with increased risk of oral and dental diseases. In this study, we sought to quantify HIV-associated differences in the prevalence and severity of dental caries in the primary and permanent dentition of 4–11-year-old Nigerian Children.

Methods

We used clinical, laboratory, demographic, and behavioral data obtained from an ongoing cohort study of age-matched HIV-infected (HI, n = 181), HIV-exposed-but-uninfected (HEU, n = 177), and HIV-unexposed-and-uninfected (HUU, n = 186) children. Measures of dental caries experience (i.e., prevalence and severity) were based on dmft/DMFT indices recorded by trained and calibrated clinical examiners. Differences in primary and permanent dentition caries experience between HI, HEU, and HUU were estimated using multivariable logistic and negative binomial regression modeling.

Results

HI children had significantly higher caries experience (33%) compared to HEU (15%) and HUU (22%) children. This difference persisted in fully adjusted analyses [odds ratio (OR) = 1.6; 95% confidence interval (CI) = 1.0–2.6], was most pronounced in the permanent dentition (OR = 3.4; 95% CI = 1.2–9.5), and mirrored differences in caries severity. While molars were predominantly affected in both primary and permanent dentitions, caries lesion patterns differed between dentitions. Caries severity was significantly associated with hypoplastic primary teeth, gingival inflammation, and lower CD4 counts.

Conclusions

We found that the higher prevalence and severity of dental caries among HI children was driven by increased burden of permanent dentition caries compared to their uninfected counterparts. The dentition-specific associations identified in this study highlight the need to design and implement age-specific caries prevention strategies. These may include intensified oral hygiene regimens aimed at mitigating the cariogenic impact of hyposalivation among HI children. Similarly, the long-lasting impacts of developmental defects of the enamel in the primary and permanent dentitions must not be ignored.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12903-022-02421-w.

Mucosal immune cell populations and the bacteriome of adenoids and tonsils from people living with HIV on suppressive antiretroviral therapy

Ear, nose, and throat (ENT) conditions are prevalent in people living with HIV (PLWH) and occur at all strata of CD4 counts and despite antiretroviral therapy (ART). ENT conditions are underreported in PLWH. Also, little is known about the adenotonsillar microbiota and its relation to resident adaptive and innate immune cells. To bridge this gap, we characterized immune cell populations and the bacterial microbiota of two anatomical sites (adenoids, tonsils) and the oral cavity. Adenoids and tonsils were obtained from PLWH (n = 23) and HIV-seronegative individuals (SN, n = 16) after nasal surgery and tonsillectomy and processed for flow cytometry. Nasopharyngeal, oropharyngeal swabs, and oral rinses were collected prior to surgery for 16S sequencing. Wilcoxon rank sum test, principal coordinate analysis, permutational multivariate analysis of variance, and linear discriminant analysis (LEfSe) were used to assess differences between PLWH and SN. Spearman’s correlations were performed to explore interactions between the bacteriome and mucosal immune cells. Of the 39 individuals included, 30 (77%) were men; the median age was 32 years. All PLWH were on ART, with a median CD4 of 723 cells. ENT conditions were classified as inflammatory or obstructive, with no differences observed between PLWH and SN. PLWH had higher frequencies of activated CD4+ and CD8+ T cells, increased T helper (Th)1 and decreased Th2 cells; no differences were observed for B cells and innate immune cells. Alpha diversity was comparable between PLWH and SN at all 3 anatomical sites (adenoids, tonsils, and oral cavity). The impact of HIV infection on the bacterial community structure at each site, as determined by Permutational multivariate analysis of variance, was minor and not significant. Two discriminant genera were identified in adenoids using LEfSe: Staphylococcus for PLWH and Corynebacterium for SN. No discriminant genera were identified in the oropharynx and oral cavity. Niche-specific differences in microbial diversity and communities were observed. PLWH shared less of a core microbiota than SN. In the oropharynx, correlation analysis revealed that Th17 cells were inversely correlated with bacterial richness and diversity, Filifactor, Actinomyces and Treponema; and positively correlated with Streptococcus. Our study contributes toward understanding the role of the adenotonsillar microbiota in the pathophysiology of ENT conditions.

Clinical Oral Condition Analysis and the Influence of Highly Active Antiretroviral Therapy on Human Salivary Microbial Community Diversity in HIV-Infected/AIDS Patients

The purpose of this study was to assess the clinical oral status and investigate the effect of highly active antiretroviral therapy (HAART) on oral flora diversity in human immunodeficiency virus (HIV)-infected/acquired immune deficiency syndrome (AIDS) patients. We first recorded and analyzed the demographic indicators of 108 HIV-infected patients and assessed their periodontal health, dental health and oral lesion status by oral examination. Besides, we compared the changes in salivary microbial communities of healthy controls, before and after treatment of HAART-processed AIDS patients by Roche 454 sequencing and RT-qPCR. In HIV-infected/AIDS patients, age, sex, marital status, income level, smoking and oral health behaviors had an effect on periodontal clinical indicators; age and marital status were correlated with dental clinical indicators; most of them were accompanied by oral manifestations, mainly including candidiasis albicans, salivary gland disease, AIDS-associated periodontitis, and oral ulcers. Besides, a total of 487 species were detected in the saliva of AIDS patients. The microbial communities of HAART-unprocessed AIDS patients significantly differed from those processed patients, with 112 unique microbial species. More importantly, a large number of conditioned pathogens were also detected in the saliva samples of AIDS patients, which may be associated with opportunistic infections. Therefore, HAART might have a crucial role in salivary microecological balance in AIDS patients. And these patients should pay attention to the maintenance of oral health, and the early initiation of HAART may be important for the development of oral lesions.

Determinants and Interactions of Oral Bacterial and Fungal Microbiota in Healthy Chinese Adults

Numerous studies have examined the composition of and factors shaping the oral bacterial microbiota in healthy adults; however, similar studies on the less dominant yet ecologically and clinically important fungal microbiota are scarce. In this study, we characterized simultaneously the oral bacterial and fungal microbiomes in a large cohort of systemically healthy Chinese adults by sequencing the bacterial 16S rRNA gene and fungal internal transcribed spacer. We showed that different factors shaped the oral bacterial and fungal microbiomes in healthy adults. Sex and age were associated with the alpha diversity of the healthy oral bacterial microbiome but not that of the fungal microbiome. Age was also a major factor affecting the beta diversity of the oral bacterial microbiome; however, it only exerted a small effect on the oral fungal microbiome when compared with other variables. After controlling for age and sex, the bacterial microbiota structure was most affected by marital status, recent oral conditions and oral hygiene-related factors, whereas the fungal microbiota structure was most affected by education level, fruits and vegetables, and bleeding gums. Bacterial-fungal interactions were limited in the healthy oral microbiota, with the strongest association existing between Pseudomonas sp. and Rhodotorula dairenensis. Several bacterial amplicon sequence variants (ASVs) belonging to Veillonella atypica and the genera Leptotrichia, Streptococcus and Prevotella_7 and fungal ASVs belonging to Candida albicans and the genus Blumeria were revealed as putative pivotal members of the healthy oral microbiota. Overall, our study has facilitated understanding of the determining factors and cross-kingdom interactions of the healthy human oral microbiome. IMPORTANCE Numerous studies have examined the bacterial community residing in our oral cavity; however, information on the less dominant yet ecologically and clinically important fungal members is limited. In this study, we characterized simultaneously the oral bacterial and fungal microbial communities in a large cohort of healthy Chinese adults, examined their associations with an array of host factors, and explored potential interactions between the two microbial groups. We showed that different factors shape the diversity and structure of the oral bacterial and fungal microbial communities in healthy adults, with, for instance, sex and age only associated with the diversity of the bacterial community but not that of the fungal community. Besides, we found that bacterial-fungal interactions are limited in the healthy oral cavity. Overall, our study has facilitated understanding of the determining factors and bacterial-fungal interactions of the healthy human oral microbial community.

Alterations in the oral microbiome in HIV infection: causes, effects and potential interventions

ABSTRACT

A massive depletion of CD4+ T lymphocytes has been described in early and acute human immunodeficiency virus (HIV) infection, leading to an imbalance between the human microbiome and immune responses. In recent years, a growing interest in the alterations in gut microbiota in HIV infection has led to many studies; however, only few studies have been conducted to explore the importance of oral microbiome in HIV-infected individuals. Evidence has indicated the dysbiosis of oral microbiota in people living with HIV (PLWH). Potential mechanisms might be related to the immunodeficiency in the oral cavity of HIV-infected individuals, including changes in secretory components such as reduced levels of enzymes and proteins in saliva and altered cellular components involved in the reduction and dysfunction of innate and adaptive immune cells. As a result, disrupted oral immunity in HIV-infected individuals leads to an imbalance between the oral microbiome and local immune responses, which may contribute to the development of HIV-related diseases and HIV-associated non-acquired immunodeficiency syndrome comorbidities. Although the introduction of antiretroviral therapy (ART) has led to a significant decrease in occurrence of the opportunistic oral infections in HIV-infected individuals, the dysbiosis in oral microbiome persists. Furthermore, several studies with the aim to investigate the ability of probiotics to regulate the dysbiosis of oral microbiota in HIV-infected individuals are ongoing. However, the effects of ART and probiotics on oral microbiome in HIV-infected individuals remain unclear. In this article, we review the composition of the oral microbiome in healthy and HIV-infected individuals and the possible effect of oral microbiome on HIV-associated oral diseases. We also discuss how ART and probiotics influence the oral microbiome in HIV infection. We believe that a deeper understanding of composition and function of the oral microbiome is critical for the development of effective preventive and therapeutic strategies for HIV infection.

HIV-Associated Interactions Between Oral Microbiota and Mucosal Immune Cells: Knowledge Gaps and Future Directions

Even with sustained use of antiretroviral therapy (ART), HIV-infected individuals have an increased risk of systemic comorbid conditions and oral pathologies, including opportunistic infections, oral mucosal inflammation, and gingival and periodontal diseases. The immune-mediated mechanisms that drive this increased risk, in the context of sustained viral suppression, are unclear. HIV infection, even when controlled, alters microbial communities contributing to a chronic low-grade inflammatory state that underlies these non-HIV co-morbidities. The higher prevalence of dental caries, and mucosal and periodontal inflammation reported in HIV-infected individuals on ART is often associated with differentially abundant oral microbial communities, possibly leading to a heightened susceptibility to inflammation. This mini-review highlights current gaps in knowledge regarding the microbe-mediated oral mucosal immunity with HIV infection while discussing opportunities for future research investigations and implementation of novel approaches to elucidate these gaps. Interventions targeting both inflammation and microbial diversity are needed to mitigate oral inflammation-related comorbidities, particularly in HIV-infected individuals. More broadly, additional research is needed to bolster general models of microbiome-mediated chronic immune activation and aid the development of precise microbiota-targeted interventions to reverse or mitigate adverse outcomes.