Salivary microbiota of HIV-positive children and its correlation with HIV status, oral diseases, and total secretory IgA

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.

Impact of HIV on the Oral Microbiome of Children Living in Sub-Saharan Africa, Determined by Using an rpoC Gene Fragment Metataxonomic Approach

Children living with HIV have a higher prevalence of oral diseases, including caries, but the mechanisms underlying this higher prevalence are not well understood. Here, we test the hypothesis that HIV infection is associated with a more cariogenic oral microbiome, characterized by an increase in bacteria involved in the pathogenesis of caries. We present data generated from supragingival plaques collected from 484 children representing three exposure groups: (i) children living with HIV (HI), (ii) children who were perinatally exposed but uninfected (HEU), and (iii) unexposed and therefore uninfected children (HUU). We found that the microbiome of HI children is distinct from those of HEU and HUU children and that this distinction is more pronounced in diseased teeth than healthy teeth, suggesting that the impact of HIV is more severe as caries progresses. Moreover, we report both an increase in bacterial diversity and a decrease in community similarity in our older HI cohort compared to our younger HI cohort, which may in part be a prolonged effect of HIV and/or its treatment. Finally, while Streptococcus mutans is often a dominant species in late-stage caries, it tended to be found at lower frequency in our HI cohort than in other groups. Our results highlight the taxonomic diversity of the supragingival plaque microbiome and suggest that broad and increasingly individualistic ecological shifts are responsible for the pathogenesis of caries in children living with HIV, coupled with a diverse and possibly severe impact on known cariogenic taxa that potentially exacerbates caries. IMPORTANCE Since its recognition as a global epidemic in the early 1980s, approximately 84.2 million people have been diagnosed with HIV and 40.1 million people have died from AIDS-related illnesses. The development and increased global availability of antiretroviral treatment (ART) regimens have dramatically reduced the mortality rate of HIV and AIDS, yet approximately 1.5 million new infections were reported in 2021, 51% of which are in sub-Saharan Africa. People living with HIV have a higher prevalence of caries and other chronic oral diseases, the mechanisms of which are not well understood. Here, we used a novel genetic approach to characterize the supragingival plaque microbiome of children living with HIV and compared it to the microbiomes of uninfected and perinatally exposed children to better understand the role of oral bacteria in the etiology of tooth decay in the context of HIV exposure and infection.

Oral Microbiome in HIV-Infected Women: Shifts in the Abundance of Pathogenic and Beneficial Bacteria Are Associated with Aging, HIV Load, CD4 Count, and Antiretroviral Therapy

Human immunodeficiency virus (HIV)-associated nonacquired immunodeficiency syndrome (AIDS) conditions, such as cardiovascular disease, diabetes, osteoporosis, and dementia are more prevalent in older than in young adult HIV-infected subjects. Although the oral microbiome has been studied as a window into pathogenesis in aging populations, its relationship to HIV disease progression, opportunistic infections, and HIV-associated non-AIDS conditions is not well understood. We utilized 16S rDNA-based pyrosequencing to compare the salivary microbiome in three groups: (1) Chronically HIV-infected women >50 years of age (aging); (2) HIV-infected women <35 years of age (young adult); and (3) HIV-uninfected age-matched women. We also examined correlations between salivary dysbiosis, plasma HIV RNA, CD4⁺ T cell depletion, and opportunistic oral infections. In both aging and young adult women, HIV infection was associated with salivary dysbiosis characterized by increased abundance of Prevotella melaninogenica and Rothia mucilaginosa. Aging was associated with increased bacterial diversity in both uninfected and HIV-infected women. In HIV-infected women with oral coinfections, aging was also associated with reduced abundance of the common commensal Veillonella parvula. Patients taking antiretroviral therapy showed increased numbers of Neisseria and Haemophilus. High plasma HIV RNA levels correlated positively with the presence of Prevotella and Veillonella, and negatively with the abundance of potentially beneficial Streptococcus and Lactobacillus. Circulating CD4⁺ T cell numbers correlated positively with the abundance of Streptococcus and Lactobacillus. Our findings extend previous studies of the role of the microbiome in HIV pathogenesis, providing new evidence that HIV infection is associated with a shift toward an increased pathogenic footprint of the salivary microbiome. Taken together, the data suggest a complex relationship, worthy of additional study, between chronic dysbiosis in the oral cavity, aging, viral burden, CD4⁺ T cell depletion, and long-term antiretroviral therapy.

The lung microbiome in children with HIV-bronchiectasis: a cross-sectional pilot study

BACKGROUND

Data on the lung microbiome in HIV-infected children is limited. The current study sought to determine the lung microbiome in HIV-associated bronchiectasis and to assess its association with pulmonary exacerbations.

METHODS

A cross-sectional pilot study of 22 children (68% male; mean age 10.8 years) with HIV-associated bronchiectasis and a control group of 5 children with cystic fibrosis (CF). Thirty-one samples were collected, with 11 during exacerbations. Sputum samples were processed with 16S rRNA pyrosequencing.

RESULTS

The average number of operational taxonomy units (OTUs) was 298 ± 67 vs. 434 ± 90, for HIV-bronchiectasis and CF, respectively. The relative abundance of Proteobacteria was higher in HIV-bronchiectasis (72.3%), with only 22.2% Firmicutes. There was no correlation between lung functions (FEV1% and FEF25/75%) and bacterial community (r = 0.154; p = 0.470 and r = 0.178; p = 0.403), respectively. Bacterial assemblage of exacerbation and non-exacerbation samples in HIV-bronchiectasis was not significantly different (ANOSIM, RHIV-bronchiectasis = 0.08; p = 0.14 and RCF = 0.08, p = 0.50). Higher within-community heterogeneity and lower evenness was associated with CF (Shannon-Weiner (H') = 5.39 ± 0.38 and Pielou's evenness (J) 0.79 ± 0.10 vs. HIV-bronchiectasis (Shannon-Weiner (H') = 4.45 ± 0.49 and Pielou's (J) 0.89 ± 0.03.

CONCLUSION

The microbiome in children with HIV-associated bronchiectasis seems to be less rich, diverse and heterogeneous with predominance of Proteobacteria when compared to cystic fibrosis.

Oral status and periodontal microbiota of HIV-infected youth infected by vertical transmission

Aim: This study evaluated the oral status and microbiota of HIV+ youth infected by vertical transmission. Materials & methods: 34 HIV+ and 36 HIV- individuals (14–24 years of age) were examined for oral infections/lesions. Subgingival biofilm was collected and the microbiota determined by checkerboard DNA–DNA hybridization. Results: Over 90% of the HIV+ youth were under highly active antiretroviral therapy, but 64.6% had AIDS and 47% presented oral manifestations. HIV+ youth showed more periodontal attachment loss and inflammation than HIV- (p < 0.05), and also high prevalence of caries. Most species were detected in higher prevalence in the microbiota of HIV+ than controls. Conclusion: HIV+ youth infected by vertical transmission presented more periodontal destruction and inflammation, and greater prevalence of microbial pathogens compared with HIV- individuals.

Is salivary IgA level a potential biomarker for immunosuppression in HIV-positive children? A systematic review and meta-analysis

The aim of this systematic review was to determine whether or not assessment of salivary secretory immunoglobulin A (sIgA) levels could be a potential biomarker for immunosuppression in HIV-positive children. The Patient, Exposure, Comparative, Outcome question was "Is sIgA level a potential biomarker for immunosuppression in HIV-positive children?" Electronic and manual literature searches were conducted in indexed databases (MEDLINE, PubMed, EMBASE, ScienceDirect, and SCOPUS databases) up to and including June 2017. The primary outcome was total mean salivary levels of IgA among HIV seropositive and seronegative children (controls). The weighted mean differences (WMD) of outcomes and 95% confidence intervals (CI) for total mean salivary IgA levels were calculated using a random effect model. Six studies were included. Three studies showed significantly lower salivary IgA levels in HIV-infected children compared with controls. Two studies showed comparable IgA levels in HIV infected and controls. One study showed significantly higher levels of salivary IgA in HIV-infected children as compared to controls. Considering the total mean salivary IgA levels among HIV seropositive and seronegative children, a high degree of heterogeneity (Q value = 254.09, P < .0001, I²  = 98.82%) was noticed among both groups. The overall WMD was not significant (WMD = -1.18, 95% CI, -1.91 to -0.44, P = .39). Whether salivary IgA level is a potential biomarker for immunosuppression in HIV-positive children remains debatable because of limited information available in the current literature. Further, high-quality case-control studies with larger sample size and more solid methodological aspects are required.

Salivary IgA versus HIV and Dental Caries

INTRODUCTION

The inter-relationship of Human Immunodeficiency Virus (HIV) infection and dental caries as well as Salivary Immunoglobulin-A (S-IgA) level appear to remain under explored while a manual and electronic search of the literature was made. Hence, the present study was undertaken to assess the relationship of S-IgA and dental caries status in HIV positive children.

AIM

The aim of this study was to find out the relationship of S-IgA antibody with dental caries by measuring the concentration of IgA in saliva of HIV positive and negative children and determine the dental caries status in HIV positive and HIV negative children, which may help in treatment planning and prevention of the same.

MATERIALS AND METHODS

A total of 28 HIV positive children aged between 6-14 years and 28 age matched HIV negative children were included in this study and both samples were randomly selected from the same Non-Governmental Organization (NGO). The HIV status of both these samples was confirmed from their medical records provided by the NGO. Only 2cc of unstimulated saliva was collected from both groups in special tubes coded numerically using the method described by Collins and Dawes and the samples were analyzed to measure the concentration of IgA using commercially available ELISA kit (DRG Diagnostics, Germany). Examination of dental caries was carried out according to WHO criteria (1997) using a flat mouth mirror and CPI probe.

RESULTS

In HIV +ve group mean S-IgA level was calculated as 81.61 ± 6.20 μg/ml, mean DMFT was 3.86 ± 3.37, mean deft was 4.75 ± 2.86. In HIV -ve group mean S-IgA level was calculated as 145.57 ± 17.83μg/ml, mean DMFT was 2.54 ± 0.69, mean deft was 2.43 ± 2.01. Strong-ve correlation between S-IgA and DMFT (r = -0.781, t = 6.38, p < 0.001) and negative but Not Significant (N.S.) correlation (r = -0.19, t = 0.99, p > 0.05) between S-IgA and deft was found in HIV +ve group. Strong -ve correlation between S-IgA and DMFT (r = -0.655, t = 4.42, p < 0.001), S-IgA and deft (r = -0.942, t =14.32, p=<0.001) was found in HIV-ve group.

CONCLUSION

This study suggests that the individuals who are suffering from IgA deficiency in general, are more susceptible to dental caries than normal individuals.

Prevalence of oral candidiasis in HIV/AIDS children in highly active antiretroviral therapy era. A literature analysis

SummaryHighly active antiretroviral therapy has decreased the morbidity and mortality related to HIV infection, including oral opportunistic infections. This paper offers an analysis of the scientific literature on the epidemiological aspects of oral candidiasis in HIV-positive children in the combination antiretroviral therapy era. An electronic databases search was made covering the highly active antiretroviral therapy era (1998 onwards). The terms used were oral lesions, oral candidiasis and their combination with highly active antiretroviral therapy and HIV/AIDS children. The following data were collected from each paper: year and country in which the investigation was conducted, antiretroviral treatment, oral candidiasis prevalence and diagnostic parameters (clinical or microbiological). Prevalence of oral candidiasis varied from 2.9% in American HIV-positive children undergoing highly active antiretroviral therapy to 88% in Chilean HIV-positive children without antiretroviral therapy. With respect to geographical location and antiretroviral treatment, higher oral candidiasis prevalence in HIV-positive children on combination antiretroviral therapy/antiretroviral therapy was reported in African children (79.1%) followed by 45.9% reported in Hindu children. In HIV-positive Chilean children on no antiretroviral therapy, high oral candidiasis prevalence was reported (88%) followed by Nigerian children (80%). Oral candidiasis is still frequent in HIV-positive children in the highly active antiretroviral therapy era irrespective of geographical location, race and use of antiretroviral therapy.

Salivary Microbiota Associated with Immunoglobulin A Nephropathy

This study aimed at investigating the salivary microbiota of 28 patients affected by immunoglobulin A nephropathy (IgAN). Fourteen healthy volunteers (HC) were used as control. Compared to HC, the number of some cultivable bacteria groups (e.g., total anaerobes) significantly (P < 0.05) decreased in the salivary samples of IgAN patients. Total bacteria from salivary samples of IgAN patients and HC subjects were analyzed by pyrosequencing of 16S rRNA gene. Paired t test showed no significant (P > 0.05) differences of alpha-diversity parameters (OTU, ACE, Chao1, and Shannon index) between the salivary samples of HC and IgAN patients. The difference for the community structure was further analyzed using three phylogeny-based beta-diversity measures. Compared to HC, the ratio between Firmicutes/Proteobacteria markedly decreased in IgAN patients. Gemella haemolysins, Granulicatella adiacens, and Veillonella parvula were positively associated (P < 0.05) with HC. Within the phylum Bacteroidetes, Prevotella species (Prevotella nigrescens, Prevotella intermedia, Prevotella pallens, and Prevotella salivae) were the highest in HC. The only exception was for Prevotella aurantiaca. Compared to HC, the percentage of abundance of some species, belonging to Pasteurellaceae family (e.g., Haemophylus parainfluenzae), increased in IgAN patients. Fusobacteriaceae (Fusobacterium) and Corynebacterium sp. also differed between the salivary samples of HC and IgAN patients.

Highly-active antiretroviral therapy and oral opportunistic microorganisms in HIV-positive individuals of Thailand

AIM

Oral mucosal lesions and opportunistic microorganisms in HIV-positive Thais treated with highly-active antiretroviral therapy (HAART) for more than 5 years were investigated.

METHODS

A total of 221 HIV-infected patients, comprising 148 HIV patients undergoing HAART for more than 5 years, 20 non-HAART HIV patients, 53 vertically-transmitted (VT) HAART HIV patients, and 30 HIV-negative controls, were examined for CD4+ counts, viral load, saliva secretion rate, and oral mucosal lesions. Samples from the tongue, gingival crevices, and mucosal lesions when present were cultured for the amounts of Candida, staphylococci, enterococci, and aerobic Gram-negative bacilli.

RESULTS

HAART (including HIV-VT) maintained oral microbial homeostasis predominated by alpha-hemolytic streptococci similar to the non-HIV controls and with a low prevalence of mucosal lesions. The HAART group had a reduced saliva secretion rate. The frequency and load of opportunistic microorganisms in the HAART group were similar to the non-HAART group, which was significantly higher than the HIV-negative controls. Candida spp. was found significantly more frequently on the tongue in HIV-infected individuals with CD4+ counts <500 cells/mm(3).

CONCLUSION

Although we did not find lower levels of mucosal lesions among HAART compared to non-HAART individuals, HAART therapy could prolong the time before opportunistic oral pathogens overwhelm the commensal members of oral microbiota.

The same microbiota and a potentially discriminant metabolome in the saliva of omnivore, ovo-lacto-vegetarian and Vegan individuals

The salivary microbiota has been linked to both oral and non-oral diseases. Scant knowledge is available on the effect of environmental factors such as long-term dietary choices on the salivary microbiota and metabolome. This study analyzed the microbial diversity and metabolomic profiles of the saliva of 161 healthy individuals who followed an omnivore or ovo-lacto-vegetarian or vegan diet. A large core microbiota was identified, including 12 bacterial genera, found in >98% of the individuals. The subjects could be stratified into three “salivary types” that differed on the basis of the relative abundance of the core genera Prevotella, Streptococcus/Gemella and Fusobacterium/Neisseria. Statistical analysis indicated no effect of dietary habit on the salivary microbiota. Phylogenetic beta-diversity analysis consistently showed no differences between omnivore, ovo-lacto-vegetarian and vegan individuals. Metabolomic profiling of saliva using ¹H-NMR and GC-MS/SPME identified diet-related biomarkers that enabled a significant discrimination between the 3 groups of individuals on the basis of their diet. Formate, urea, uridine and 5-methyl-3-hexanone could discriminate samples from omnivores, whereas 1-propanol, hexanoic acid and proline were characteristic of non-omnivore diets. Although the salivary metabolome can be discriminating for diet, the microbiota has a remarkable inter-individual stability and did not vary with dietary habits. Microbial homeostasis might be perturbed with sub-standard oral hygiene or other environmental factors, but there is no current indication that a choice of an omnivore, ovo-lacto-vegetarian or vegan diet can lead to a specific composition of the oral microbiota with consequences on the oral homeostasis.

Microbiome in human immunodeficiency virus infection

Human immunodeficiency virus (HIV) primary infection occurs at mucosa tissues, suggesting an intricate interplay between the microbiome and HIV infection. Recent advanced technologies of high-throughput sequencing and bioinformatics allow researchers to explore nonculturable microbes, including bacteria, virus, and fungi, and their association with diseases. HIV/simian immunodeficiency virus infection is associated with microbiome shifts and immune activation that may affect the outcome of disease progression. In this review, the authors focus on microbiome in HIV infection at various mucosal compartments. Understanding the relationship between microbiome and HIV may offer insights into development of better strategies for HIV prevention and treatment.

Periodontal disease in HIV/AIDS

Since the early 1990's, the death rate from AIDS among adults has declined in most developed countries, largely because of newer antiretroviral therapies and improved access to these therapies. In addition, from 2006 to 2011, the total number of new cases of HIV infection worldwide has declined somewhat and has remained relatively constant. Nevertheless, because of the large numbers of existing and new cases of HIV infection, the dental practitioner and other healthcare practitioners will still be required to treat oral and periodontal conditions unique to HIV/AIDS as well as conventional periodontal diseases in HIV-infected adults and children. The oral and periodontal conditions most closely associated with HIV infection include oral candidiasis, oral hairy leukoplakia, Kaposi's sarcoma, salivary gland diseases, oral warts, other oral viral infections, linear gingival erythema and necrotizing gingival and periodontal diseases. While the incidence and prevalence of these oral lesions and conditions appear to be declining, in part because of antiretroviral therapy, dental and healthcare practitioners will need to continue to diagnose and treat the more conventional periodontal diseases in these HIV-infected populations. Finding low-cost and easily accessible and acceptable diagnostic and treatment approaches for both the microbiological and the inflammatory aspects of periodontal diseases in these populations are of particular importance, as the systemic spread of the local microbiota and inflammatory products of periodontal diseases may have adverse effects on both the progression of HIV infection and the effectiveness of antiretroviral therapy approaches. Developing and assessing low-cost and accessible diagnostic and treatment approaches to periodontal diseases, particularly in developing countries, will require an internationally coordinated effort to design and conduct standardized clinical trials.

Effect of probiotic bacteria on microbial host defense, growth, and immune function in human immunodeficiency virus type-1 infection

The hypothesis that probiotic administration protects the gut surface and could delay progression of Human Immunodeficiency Virus type1 (HIV-1) infection to the Acquired Immunodeficiency Syndrome (AIDS) was proposed in 1995. Over the last five years, new studies have clarified the significance of HIV-1 infection of the gut associated lymphoid tissue (GALT) for subsequent alterations in the microflora and breakdown of the gut mucosal barrier leading to pathogenesis and development of AIDS. Current studies show that loss of gut CD4+ Th17 cells, which differentiate in response to normal microflora, occurs early in HIV-1 disease. Microbial translocation and suppression of the T regulatory (Treg) cell response is associated with chronic immune activation and inflammation. Combinations of probiotic bacteria which upregulate Treg activation have shown promise in suppressing pro inflammatory immune response in models of autoimmunity including inflammatory bowel disease and provide a rationale for use of probiotics in HIV-1/AIDS. Disturbance of the microbiota early in HIV-1 infection leads to greater dominance of potential pathogens, reducing levels of bifidobacteria and lactobacillus species and increasing mucosal inflammation. The interaction of chronic or recurrent infections, and immune activation contributes to nutritional deficiencies that have lasting consequences especially in the HIV-1 infected child. While effective anti-retroviral therapy (ART) has enhanced survival, wasting is still an independent predictor of survival and a major presenting symptom. Congenital exposure to HIV-1 is a risk factor for growth delay in both infected and non-infected infants. Nutritional intervention after 6 months of age appears to be largely ineffective. A meta analysis of randomized, controlled clinical trials of infant formulae supplemented with Bifidobacterium lactis showed that weight gain was significantly greater in infants who received B. lactis compared to formula alone. Pilot studies have shown that probiotic bacteria given as a supplement have improved growth and protected against loss of CD4+ T cells. The recognition that normal bacterial flora prime neonatal immune response and that abnormal flora have a profound impact on metabolism has generated insight into potential mechanisms of gut dysfunction in many settings including HIV-1 infection. As discussed here, current and emerging studies support the concept that probiotic bacteria can provide specific benefit in HIV-1 infection. Probiotic bacteria have proven active against bacterial vaginosis in HIV-1 positive women and have enhanced growth in infants with congenital HIV-1 infection. Probiotic bacteria may stabilize CD4+ T cell numbers in HIV-1 infected children and are likely to have protective effects against inflammation and chronic immune activation of the gastrointestinal immune system.