In vitro demonstration of cellular hypersensitivity to strep 2A in recurrent aphthous stomatitis by means of the leucocyte migration test

New insight into function and dysfunction of gut microfold cells

Microfold cells (M cells), derived from intestinal crypt Lgr5⁺ stem cells, are distributed in gut-associated lymphoid tissue (GALT), nasopharyngeal-associated lymphoid tissue (NALT), and bronchial-associated lymphoid tissue (BALT). The basement membrane of mature M cells protrudes upward, showing a "pocket-like" shape. M cell differentiation is mainly regulated by two pathways, one is the non-canonical NF-κB pathway, and the other is the canonical NF-κB pathway. The differentiation and maturation of M cells are closely related to RANKL and S100A4. M cells can not only transport antigens and trigger an immune response, but also are the gateway for various pathogens to invade the body. The occurrence and development of tuberculosis, prion disease, and Crohn's disease are closely related to M cells.

Recurrent Aphthous Stomatitis

Recurrent aphthous stomatitis is a chronic inflammatory disease of the oral mucosa. It is characterized by painful mouth ulcers that cannot be explained by an underlying disease. Recurrent oral mucosal ulcers require a proper differential diagnosis to rule out other possible causes before recurrent aphthous stomatitis is diagnosed. The condition is common, with prevalence rates ranging from 5 to 60% in different series. Its pathogenesis is unknown, but multiple factors are considered to play a part. There are no standardized treatments for this condition and none of the treatments are curative. The goal of any treatment should be to alleviate pain, reduce the duration of ulcers, and prevent recurrence.

The oral microbiota of patients with recurrent aphthous stomatitis

BACKGROUND

Specific pathogenic bacteria have been implicated in recurrent aphthous stomatitis (RAS), a chronic inflammatory condition characterised by ulcerations in the oral mucosa. However, the aetiology behind this condition still remains unclear.

OBJECTIVE

The buccal microbiota of patients with RAS was compared to that of control subjects to investigate its potential role for this condition.

DESIGN

Buccal swabs were obtained from non-ulcerative areas of 60 patients, of whom 42 patients had lesions at the time of sampling, and 60 healthy age- and gender-matched controls. Bacterial DNA was extracted and analysed by Terminal-Restriction Fragment Length Polymorphism, using enzymatic digestion of the polymerase chain reaction-amplified 16S rRNA gene, yielding a series of peaks, each representing a bacterial taxon.

RESULTS

Two peaks, 60 and 489, were more prevalent in patients with RAS than controls. Conversely, peaks 58 and 490 were less common in patients than controls. When the patients were divided into subgroups, we found that the observed differences in peak-pattern were related to the presence of lesions during sampling.

CONCLUSIONS

The microbiota of the non-inflamed buccal mucosa differed between patients and controls. The differences were most pronounced in patients who presented with lesions during sampling, suggesting that a disturbance in the normal buccal microbiota triggers the presence of lesions or that presence of lesions alters the microbiota.

Recurrent aphthous stomatitis: a review

Recurrent aphthous stomatitis (RAS) is a common clinical condition producing painful ulcerations in oral cavity. The diagnosis of RAS is based on well-defined clinical characteristics but the precise etiology and pathogenesis of RAS remain unclear. The present article provides a detailed review of the current concepts and knowledge of the etiology, pathogenesis, and management of RAS.

Recurrent aphthous stomatitis

The cause of recurrent aphthous stomatitis (RAS) remains unknown despite considerable research. This article reviews the evidence for current theories regarding this disorder, including possible suspected relationships with microbial and immunologic factors, and presents medical diseases that mimic RAS lesions in certain patients. Topical management of the common form of minor RAS is described along with systemic therapy currently available to patients with severe forms of this disease.

Oral mucosal antigen reactivity during exacerbation and remission phases of recurrent aphthous ulceration

Pooled serum from subjects with active recurrent aphthous ulceration (RAU) and from control subjects was tested against indigenous surface mucosal material from subjects with active RAU, remission RAU subjects, and normal subjects. IgM antibody reactivity in both sera was significantly higher to material from remission RAU subject mucosa than to material from control subjects or subjects with active RAU. IgG antibody activity in both sera was significantly lower to material from active RAU subject mucosa than to material from control subjects or subjects whose RAU was in remission. These results suggest that the character and amount of antigen on mucosa may differ during the pathogenesis of RAU.

Serum antibody responses to indigenous oral mucosal antigens and selected laboratory-maintained bacteria in recurrent aphthous ulceration

Sera from subjects with recurrent aphthous ulceration (RAU) and control subjects were tested for relative levels of IgM, IgG, and IgA antibodies against eight selected laboratory-maintained bacteria, including Streptococcus sanguis which has been implicated in the etiopathogenesis of RAU. There were no differences in relative serum antibody levels for any isotype against any bacteria between control and RAU groups. RAU subjects with active lesions were then paired with control subjects, and each serum was tested against sedimentable material derived from the oral mucosa of each pair member. The analysis of data indicated that RAU and control subjects had similar levels of serum antibodies to indigenous mucosal antigens, but RAU subjects had significantly less antigenic material than control subjects.

Immunogenetic markers and immune response in patients with recurrent oral ulceration

20 patients, aged 20 to 72 years (mean 36.5 years), 14 with recurrent (RAS) and 6 with recurrent cicatrizing (RCAS) aphthous stomatitis were studied. 3 patients (15%) had the HLA locus A11 antigen, whose frequency in the Finnish population is 8%. 5 patients (25%) had B12, which occurs in 15% of the normal population. Results of routine serological tests were normal. All had normal serum levels of IgG, IgM, IgA and complements C3 and C4. 4 patients, 2 with RAS and 2 with RCAS, had raised serum IgE. Precipitating antibodies against milk protein were detected in 2 patients and against gluten in 1. In 4 patients, tests for immediate allergy were positive. 5 patients had antibodies to double-stranded DNA. Delayed hypersensitivity reactions were normal, and the PHA stimulation of lymphocytes elicited normal T-cell responses in all patients except one with RCAS. In this patient, there was a striking parallelism between an increase in PHA-reactive lymphocytes and clinical improvement. The serum of this patient contained a binder for 125I-labelled PHA, a binder not consistently detected in the other patients with ROU. Lymphocyte dysfunction may play a rôle in ROU. Of the 16 biopsy specimens of aphthous tissue studied by direct immunofluorescence for IgG, IgM, IgA, fibrinogen and C3, 15 specimens contained deposits of C3 in and along mucosal vessels, whereas among the 15 controls only 1 specimen of erosive lichen planus showed deposits of C3 along capillary walls. Immune complexes precipitating in capillary walls appear to be a common feature of ROU.

An immunoelectrophoretic analysis of the Strep. sanguis and adult human oral mucosa antigen extracts used for immunological investigations of recurrent aphthous stomatitis

Water-soluble antigens of Strep. sanguis strain 2A, ATCC 10556, and adult human oral mucosa (AHOM) were analysed by four immunoelectrophoretic methods. Crossed immunoelectrophoresis (CIE), using rabbit antibodies raised against the soluble antigens, revealed 26 antigens in the standard Strep. sanguis antigen extract and 16 antigens in the standard adult human oral mucosa extract. All 26 Strep. 2A antigen-antibody precipitates observed in the CIE were identified as streptococcal components. Eleven of the AHOM antigen-antibody precipitates in the CIE were derived from human serum proteins and hemoglobin present in the crude AHOM-Ag extract. Five of the latter precipitates possibly were caused by oral mucosal antigens. The AHOM-Ag extract contained four bacterial contaminants. None of them influenced the crossed immunoelectrophoretic AHOM antigen-antibody reference pattern in the present study.

Recurrent aphthous stomatitis: clinical characteristics and evidence for an immunopathogenesis

Recurrent aphthous stomatitis is one of the most common diseases affecting the oral mucosa, and one of its variants is the most painful affliction of the oral mucosa. The lesions of recurrent aphthous stomatitis can be manifested as part of a broad spectrum of clinical disease ranging from the common minor aphthous ulcers to Behçet's syndrome. Differential diagnosis, although not often difficult, must include many conditions capable of producing erosive and ulcerative oral mucosal lesions. The salient features of recurrent aphthous stomatitis suggest that it is a heterogeneous entity. Recent immunologic investigations have focused attention on a possible immunopathogenesis and the evidence for this is reviewed.

HL-A histocompatibility antigens in recurrent aphthous ulceration

The frequency of HL-A phenotypes has been investigated in 64 patients who had recurrent aphthous ulcers and 100 subjects who did not. The HL-A phenotypes were determined by a two-step microcytotoxicity test on peripheral blood lymphocytes, incubating these cells with a range of defined antiserums and complement and subsequently assessing lymphocyte viability by dye exclusion. There were no significant differences between the frequency of individual HL-A antigens in the patients with aphthous ulceration and those of subjects without aphthous ulceration. Similarly, no differences in numbers of shared antigens could be demonstrated. The distribution of HL-A antigens was essentially similar in subdivisions of patients with aphthous ulceration, grouped on the basis of sex, family history, age at onset, and maximum number of concurrent ulcers and their duration before healing.

Comparison of cellular and humoral immunity against streptococcal and adult human oral mucosa antigens in relation to exacerbation or recurrent aphthous stomatitis

Cell-mediated immunity (CMI) and humoral mediated immunity (HMI) against streptococcal and adult human oral mucosa (AHOM) antigens were investigated in patients with inactive and active recurrent aphthous stomatitis (RAS). The CMI and HMI were examined by means of the leucocyte migration test (LMT) and a double layer immunofluorescence (IF) technique. The CMI against Streptococcus sanguis strain 2A, streptococcus pyogenes strain M5, and AHOM was significantly increased in inactive and active RAS. Significant difference between active and inactive RAS was only demonstrated when Strep. 2A was used as antigen in the leucocyte migration cultures. Longitudinal observations in relation to exacerbation of RAS revealed significant changes in the migration indices (MI) when Strep. 2A and AHOM were used as antigens. Extracts of Strep. M5 and other tissues as kidney and uterus did not show any significant changes of MI in relation to the exacerbation of RAS. The IF-investigations detected significantly raised IgG antibodies against washed whole cells of Streptococcus sanguis strain 2A and Streptococcus pyogenes strain M5 in sera from patients with RAS. The autoantibodies in RAS belonged to the immunoglobulin classes IgG and IgM. The detected antibodies were able to blind serum complement (C3). The distribution of endpoint titres (EPT) against Strep. 2A, Strep. M5, and AHOM antigens did not differ significantly in patients with active RAS in relation to those with inactive RAS. Furthermore, the EPT against Strep. 2A and AHOM were not significantly changed in relation to exacerbation of RAS. The present investigations show that CMI and HMI against streptococcal and AHOM antigens are characteristic features of RAS and indicate that the CMI against Strep. 2A and AHOM is significantly increased in relation to exacerbation of RAS.

A leucocyte migration study on the cell-mediated immunity against adult human oral mucosa and streptococcal antigens in patients with recurrent aphthous stomatitis

In vitro demonstration of cell-mediated immunity (CMI) against adult human oral mucosa antigen (AHOM) and streptococcal antigens was accomplished by means of the leucocyte migration test (LMT) in patients with recurrent aphthous stomatitis (RAS). If antigenic extracts of AHOM, Streptococcus sanguis strain 2A or Streptococcus pyogenes strain M5 were used in the LMT experiments, the distribution of migration indices (MI) over patients with RAS differed significantly from the distribution over the controls. In patients with other oral lesions, these MI-distributions did not differ significantly from those among the controls. Extracts of other tissues such as kidney and uterus tissues or of other bacterial antigens such as Brucella abortus and Escherichia coli did not reveal any significant differences between the LMT responses in RAS and controls. The present findings show that CIM against AHOM antigen and streptococcal antigens are features characteristic of RAS. Furthermore, the results indicate that common antigenic determinants might be shared by AHOM and streptococci.

An immunofluorescence study on the cross-reaction between strep. 2a and human oral mucosa

Immunologic cross-reactions between Strep. 2A, fetal human oral mucosa (FHOM), and adult human oral mucosa (AHOM) were investigated by the use of a double layer immunofluorescence staining technique. Rabbit sera were prepared against Strep. 2A and FHOM. Seventeen sera from patients with recurrent aphthous stomatitis (RAS) and with known antibodies against Strep. 2A and AHOM were examined for antibodies against FHOM. The distribution of endpoint titers against FHOM in the sera from RAS differed significantly from the distribution in 17 controls. The immune absorptions in the rabbit sera and in the 17 sera from patients with RAS indicate that some cross-reacting antigenic determinants are shared between Strep. 2A, FHOM, and AHOM. Further, the present results indicate that antibodies are produced against antigenic determinants which are not shared by Strep. 2A, FHOM, and AHOM. The role of cross-reacting antigens in the pathogenesis of RAS is discussed but remains obscure.

Immunological study of typhoid: immunoglobulins, C3, antibodies, and leukocyte migration inhibition in patients with typhoid fever and TAB-vaccinated individuals

The development of humoral and cell-mediated immune responses to Salmonella typhi antigens and immunoglobulin and C(3) levels were determined in patients suffering from typhoid fever, TAB-vaccinated individuals, and appropriate controls. In 45 patients with typhoid, a significant elevation of immunoglobulin M (IgM) level was noted from the first week of illness onwards. Eighteen TAB-vaccinated persons also showed a significant elevation of IgM levels. In typhoid sera, the anti-O and anti-H antibodies were mostly 2-mercaptoethanol (2-ME) sensitive. The rise of IgM level correlated well with the 2-ME-sensitive anti-O and anti-H antibodies seen in typhoid patients. The anti-O antibodies in the TAB-vaccinated group were almost entirely 2-ME sensitive, but both 2-ME-sensitive and -resistant anti-H antibodies were detected in the TAB group. A marked increas in C(3) level was also noted in patients with typhoid. The cell-mediated immunity (CMI), as measured by leukocyte migration inhibition tests, was demonstrable in 15 of 22 patients with typhoid. On the other hand, only 8 of the 20 normal subjects, 5 of the 16 fever control cases, and 6 of the 18 TAB-vaccinated individuals gave a positive CMI. The latter three groups were comparable with each other but were significantly different from the typhoid patients. It was concluded that TAB-vaccination did not induce CMI even though it induced the development of antibodies, the latter being comparable with those of the patients with typhoid. The significance of these findings is discussed.