Salivary IgA responses to bacteria in dental plaque as related to periodontal and HIV infection status

Current trends and new developments in HIV research and periodontal diseases

With the advent of combined antiretroviral therapies, the face of HIV infection has changed dramatically from a disease with almost certain mortality from serious comorbidities, to a manageable chronic condition with an extended lifespan. In this paper we present the more recent investigations into the epidemiology, microbiology, and pathogenesis of periodontal diseases in patients with HIV, and the effects of combined antiretroviral therapies on the incidence and progression of these diseases both in adults and perinatally infected children. In addition, comparisons and potential interactions between the HIV-associated microbiome, host responses, and pathogenesis in the oral cavity with the gastrointestinal tract and other areas of the body are presented. Also, the effects of HIV and combined antiretroviral therapies on comorbidities such as hyposalivation, dementia, and osteoporosis on periodontal disease progression are discussed.

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.

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.

Secretory immunity with special reference to the oral cavity

The two principal antibody classes present in saliva are secretory IgA (SIgA) and IgG; the former is produced as dimeric IgA by local plasma cells (PCs) in the stroma of salivary glands and is transported through secretory epithelia by the polymeric Ig receptor (pIgR), also named membrane secretory component (SC). Most IgG in saliva is derived from the blood circulation by passive leakage mainly via gingival crevicular epithelium, although some may be locally produced in the gingiva or salivary glands. Gut-associated lymphoid tissue (GALT) and nasopharynx-associated lymphoid tissue (NALT) do not contribute equally to the pool of memory/effector B cells differentiating to mucosal PCs throughout the body. Thus, enteric immunostimulation may not be the best way to activate the production of salivary IgA antibodies although the level of specific SIgA in saliva may still reflect an intestinal immune response after enteric immunization. It remains unknown whether the IgA response in submandibular/sublingual glands is better related to B-cell induction in GALT than the parotid response. Such disparity is suggested by the levels of IgA in submandibular secretions of AIDS patients, paralleling their highly upregulated intestinal IgA system, while the parotid IgA level is decreased. Parotid SIgA could more consistently be linked to immune induction in palatine tonsils/adenoids (human NALT) and cervical lymph nodes, as supported by the homing molecule profile observed after immune induction at these sites. Several other variables influence the levels of antibodies in salivary secretions. These include difficulties with reproducibility and standardization of immunoassays, the impact of flow rate, acute or chronic stress, protein loss during sample handling, and uncontrolled admixture of serum-derived IgG and monomeric IgA. Despite these problems, saliva is an easily accessible biological fluid with interesting scientific and clinical potentials.

Serum antibody levels in smoker and non-smoker saudi subjects with chronic periodontitis

BACKGROUND

Cigarette smoking is a significant risk factor for the initiation and progression of periodontal disease. Studies have shown altered serum and gingival crevicular fluid inflammatory cytokine profiles, immune cell function, and altered proteolytic regulation in smokers. The observations are not consistent, and to date, there is no clear mechanism to explain how smoking may affect periodontal disease. Hence, the present study was undertaken to assess the alterations of serum immunoglobulin levels in smokers with periodontitis and its potential role as a risk indicator of the disease process.

METHODS

In this study, 30 patients who smoked and 30 patients who did not smoke with chronic periodontitis and 30 healthy subjects were enrolled. Serum immunoglobulin (Ig) G, IgA, and IgM levels were estimated with immunoturbidimetric assay. The IgG subclass (IgG1, IgG2, IgG3, and IgG4) levels were performed using single radial immunodiffusion assay.

RESULTS

Levels of serum IgG and IgA were significantly lower in smokers compared to non-smokers and healthy controls (P <0.001). Although IgM levels were low in smokers, it was not significant. Of the four subclasses of IgG studied, the IgG2 was found to be significantly lower among smokers with periodontitis.

CONCLUSIONS

Current observations indicate that cigarette smoking may be associated with the suppression of B-cell function and immunoglobulin production. The alteration of antibody levels further explains the potential mechanism by which smoking exacerbates periodontal disease. Further studies at the molecular level may highlight the specific mechanism by which tobacco can interact with cells of the immune system and its impact on periodontal disease process.

Association of T CD4 Lymphocyte Levels and Chronic Periodontitis in HIV-Infected Brazilian Patients Undergoing Highly Active Anti-Retroviral Therapy: Clinical Results

BACKGROUND

Controversial data regarding the association between immunosuppression and prevalence/ severity of periodontal diseases in HIV infection have been reported. Thus, the aim of this study was to test the hypothesis that lower T CD4 lymphocyte levels are not related to a higher prevalence of chronic periodontitis in HIV-infected Brazilians undergoing highly active anti-retroviral therapy (HAART).

METHODS

Sixty-four HIV-infected patients under HAART were classified as having chronic periodontitis; i.e., > or = three sites with probing depth (PD) and/or clinical attachment level (CAL) > or = 5 mm or periodontal healthy (no sites with PD > 3 mm and/or CAL > 4 mm). All subjects received conventional periodontal therapy. Bleeding on probing, plaque accumulation, PD, and CAL were registered at six sites/tooth at baseline and 4 months after therapy. Epidemiological features and levels of T CD4 lymphocytes were obtained from medical records. Significance of differences in periodontal clinical parameters within and between groups were determined using Wilcoxon signed-rank and Mann-Whitney or independent sample t tests. Associations between T CD4 levels and clinical parameters were determined using the chi square test.

RESULTS

Sixty-one percent of the HIV-infected patients represented AIDS cases, although 69% of them were periodontally healthy. The overall T CD4 lymphocyte mean levels was 333 +/- 254 cells/mm3 and viral load was 12,815 +/- 24,607 copies/mm3. Yet the prevalence of chronic periodontitis was relatively low (36%). In addition, patients with periodontitis presented a moderate disease (mean PD = 2.2 +/- 0.10; mean CAL = 2.6 +/- 0.13) and responded successfully to periodontal therapy. These subjects showed higher levels of T CD4 cells, but lower counts of neutrophils than periodontally healthy patients. Among periodontally healthy and chronic periodontitis patients, 41.7% and 22.9%, respectively, had low levels of T CD4 lymphocytes. No significant differences between periodontal status and epidemiological and immunological parameters were observed.

CONCLUSION

Based on these results, the hypothesis that lower T CD4 lymphocyte levels are not associated with higher prevalence of chronic periodontitis in HIV-infected Brazilians under HAART cannot be rejected.

Salivary IgA to cariogenic bacteria in HIV-positive children and its correlation with caries prevalence and levels of cariogenic microorganisms

The interrelationship of HIV infection, dental caries and mucosal immune responses remains controversial. In our study population of 40 HIV-infected and 40 healthy control children (ages 2-5 years) there was a significantly higher prevalence of dental caries in HIV-infected children (P<0.05). The extent of caries correlated with the severity of HIV disease. To determine whether the immunosuppression that ensues after HIV infection could contribute to the increased caries prevalence, the concentrations of total IgA and IgA specific to cariogenic bacteria (Streptococcus mutans, Streptococcus sobrinus and Lactobacillus acidophilus) were determined in whole saliva by enzyme-linked immunosorbent assay. Levels of the same bacteria were also quantified in saliva using checkerboard DNA-DNA hybridization. A significantly increased level of total salivary IgA was found in the HIV-positive population (P < 0.05), but there were comparable titers of specific IgA to cariogenic bacteria in HIV-positive and healthy controls. The microbiological assessment also demonstrated similar levels of cariogenic microorganisms in both groups. We conclude that HIV-positive children appear to maintain the capacity to mount a mucosal immune response to cariogenic microorganisms, at least until late stages of disease.

Levels of parotid and submandibular/sublingual salivary immunoglobulin A in response to experimental gingivitis in humans

Salivary secretory IgA (s-IgA) is considered to act as an important first line of defense mechanism in the oral cavity. It has therefore been suggested that an increased antigenic load would induce an increase in salivary IgA production. This study investigated the pure glandular levels of salivary IgA in parotid and submandibular/sublingual (SM/SL) saliva during plaque accumulation leading to experimental gingivitis. Starting from regular oral hygiene, 14 healthy, nonsmoking men refrained from all oral hygiene measures for 12 days. On days -2, 0, 3, 6, and 12 a plaque index, a bleeding index, and unstimulated and stimulated saliva from the parotid and the SM/SL glands were measured. Salivary IgA was quantified using a sandwich ELISA. All subjects developed gingivitis as measured by a bleeding index. Compared to baseline the salivary flow rate was increased on day 12. Regarding the secretion rate of IgA there was a statistically significant increase in stimulated parotid saliva but not SM/SL saliva compared to baseline after 6 and 12 days without oral hygiene. No significant changes were observed for the concentration of IgA during the trial. Thus, in healthy subjects with regular oral hygiene the development of plaque induced gingivitis is associated with increased salivary gland output and increased total IgA output levels in stimulated parotid saliva but not in SM/SL saliva.

Salivary IgA in response to periodontal treatment

There is evidence that the quantity of antigen load is crucial for the activation of IgA immune responses. In order to investigate the relevance of these findings in aggressive periodontitis, salivary antibody responses were measured during non-surgical and antibiotic treatment. Twenty-one patients with generalized aggressive periodontitis were monitored for total salivary IgA and IgA reactive to Porphyromonas gingivalis in resting and stimulated whole saliva. Non-surgical treatment included full-mouth professional tooth cleaning and subgingival scaling and root planing (SRP) under local anesthesia. Patients were recalled at 3 months and 6 months following systemic antibiotic treatment. Non-parametric statistics showed significant improvements in the clinical parameters in all patients. Between baseline and 4 wk following SRP, median concentrations of total IgA decreased both in resting (-46%) and in stimulated (-33%) saliva. The P. gingivalis-specific IgA activity showed a twofold increase at 4 wk after SRP. In addition to these changes, periodontal treatment of aggressive periodontitis did not appear to affect salivary IgA, and there were no significant correlations of IgA to the clinical parameters. In conclusion, salivary IgA responses during periodontal treatment were not found to have a diagnostic or prognostic significance.

IgG subclass specific antibody response to periodontopathic organisms in HIV-positive patients

BACKGROUND

We previously reported an increased rate of progression of periodontal disease over an 18-month period in human immunodeficiency virus (HIV)-positive subjects compared to controls. The mechanism for disease progression and rapid tissue loss was unknown. Data on the microbiological studies failed to show any significant difference in the microbial characteristics of the periodontal lesions in HIV-positive patients compared to HIV-negative controls. Immunological analysis had identified neutrophils as an important component of the host defense against periodontal infection, especially against rapid tissue loss. Serum IgG reactivities to periodontal pathogens in HIV-positive patients with periodontitis were reduced. Other data provided circumstantial evidence to suggest that IgG subclass (IgG2) specific antibody might assist bacterial clearing in periodontal infection. The aim of the current study was to examine the specific IgG subclass antibody response to a panel of periodontopathic organisms: Actinobacillus actinomycetemcomitans (Aa), Porphyromonas gingivalis (Pg), Prevotella Intermedia (Pi), Fusobacterium nucleatum (Fn), Campylobacter rectus (Cr), and Bacteroides forsythus (Bf) in HIV-positive patients compared to HIV-negative controls.

METHODS

Sera from 120 HIV-positive patients (40 periodontitis, 69 gingivitis, and 11 no oral diseases) were tested for IgG subclass specific antibody response to the above listed 6 organisms using enzyme-linked immunosorbent assay. Data were compared with those obtained from 40 HIV-negative control subjects (35 periodontitis, 2 gingivitis, and 3 no oral diseases).

RESULTS

In the HIV-positive group, a consistently high response rate was found in IgG1 to all the bacteria tested. In addition, high levels of IgG3 and IgG4 to Pg and IgG1 and IgG2 to Pi were also present. However, no significant difference was detected among the periodontitis, gingivitis, and no oral disease subgroups. When the periodontitis patients from the HIV-positive group were compared to the HIV-negative group, no difference in the antibody levels and response rates was noted.

CONCLUSION

We conclude that in HIV-positive patients, the specific IgG subclass antibody response to periodontopathic organisms was similar to that of HIV-negative subjects.

An update on HIV and periodontal disease

With the advent of newer pharmacological approaches to the treatment of human immunodeficiency virus (HIV) infection, the incidence and progression of both atypical and conventional periodontal diseases are changing. The incidence of necrotizing periodontitis and gingival diseases of fungal origin appears to be on the decline as a result of these therapies that have led to increased life spans for HIV patients. However, in cases where these therapies lose their effectiveness and HIV patients relapse into an immunosuppressed state, these conditions may recur. Recent evidence has shown that HIV patients with more conventional periodontal diseases such as chronic periodontitis may have increased attachment loss and gingival recession when compared to their HIV-negative counterparts. This pattern of loss of periodontal support may be due in part to a diffuse invasion of opportunistic bacterial infections, viruses, and fungi into the gingival tissue, leading to a more elevated and more diffuse destructive inflammatory response in the periodontal soft and hard tissues. While the accepted approaches to treating the spectrum of periodontal diseases in HIV patients remain essentially unchanged over the past 15 years, the impact of newer systemic therapies on patient immunocompetence may influence treatment decisions.

Salivary IgA subclasses and bacteria-reactive IgA in patients with aggressive periodontitis

The local salivary immunoglobulin A (IgA) response in patients with aggressive periodontitis to oral microorganisms and its role for the pathogenesis has not been determined. This study investigated the hypothesis that aggressive periodontitis patients have impaired oral secretory immunity. Our test group was made-up of 19 aggressive periodontitis patients and 19 age- and gender-matched periodontally healthy controls. Total IgA, IgA subclass 1, IgA subclass 2 and IgA reactive to Actinobacillus actinomycetemcomitans Y4, Treponema denticola ATCC 35404 and Candida albicans DSM 3454 were determined by enzyme-linked immunosorbent assay in whole unstimulated and stimulated saliva. A statistically significantly lower concentration and secretion rate of total salivary IgA (P < 0.01) and IgA1 (P < 0.001) was found in the aggressive periodontitis group in resting and stimulated saliva. A decrease of IgA2 (P < 0.05) was seen in resting saliva. Although only minor differences were detected in the concentration and secretion of bacteria-reactive IgA in both groups, the proportion of bacteria-reactive IgA from the total IgA was significantly higher (P < 0.01) in the aggressive periodontitis group in all three microorganisms tested. Our results indicate an inhibition of total secretory IgA. In particular an IgA subclass 1-specific decrease in aggressive periodontitis was noted, while the bacteria-reactive humoral immune system in saliva was activated. The role of the decrease of IgA1 immunoglobulins in aggressive periodontitis with respect to susceptibility for periodontal diseases has to be elucidated.

Parotid salivary S-IgA antibodies during experimental gingivitis in smokers and non-smokers

Persons who smoke display a less pronounced increase of gingival bleeding in the experimental gingivitis model as compared with non-smokers. The aim of the present study was to investigate whether this could partly be explained by differences in levels of parotid total secretory IgA (S-IgA) or parotid S-IgA reactive with selected oral microorganisms. Parotid saliva samples were obtained from 11 smoking and 14 non-smoking volunteers, at baseline, after 5 and 14 days of full mouth experimental gingivitis. Output levels of total S-IgA and of specific S-IgA reactive with cell extracts from Actinobacillus actinomycetemcomitans, Actinomyces naeslundii, Campylobacter rectus, Fusobacterium nucleatum, Porphyromonas gingivalis, Prevotella intermedia, Prevotella nigrescens, Peptostreptococcus micros, Streptococcus gordonii and Streptococcus mutans were determined in the samples by means of ELISA. Smokers and non-smokers were found to have similar output levels (microg/min) of total S-IgA, and the values did not significantly change during the experimental gingivitis trial. Parotid salivary outputs (units/min) of the bacteria-specific S-IgA at baseline and at days 5 and 14, were not different between smokers and non-smokers; no changes were observed during the experimental gingivitis trial. The present observations indicate that total S-IgA and bacteria-specific S-IgA in saliva are not main factors that can explain the less pronounced increase of gingival bleeding in the experimental gingivitis model in smokers as compared with non-smokers.

Periodontal conditions and salivary immunoglobulins in individuals with Down syndrome

Periodontal conditions and salivary levels of immunoglobulins sIgA, IgM, and IgG subclass distribution and albumin, quantified by enzyme-linked immunosorbent assay, were determined in 20 patients with Down syndrome and 19 healthy controls. Gingival inflammation was more extensive (P < 0.05) among Down syndrome subjects compared to controls as well as the occurrence of periodontal pockets (> 4 mm) (P < 0.05). The immunoglobulin levels of sIgA, IgM, the sum of IgG subclasses, and the concentration of albumin did not differ significantly between the 2 groups. However, the proportion of IgG1 expressed as percentage of the sum of total IgG was significantly higher (P < 0.01) in the Down syndrome group compared to controls. On the contrary, the proportion of IgG2, IgG3, and IgG4 subclasses in saliva did not differ between the 2 groups. The results indicate an altered distribution of IgG subclasses in saliva, with a higher proportion of IgG1 in Down syndrome individuals compared to controls.