| ObjectiveThe purpose of this study was to investigate the host immunity in the onset and development of chronic periodontitis and the effects of host genotype factor on the local cellular immune response, through measuring the level of interleu-kin -1β(IL-1β) expressed in buccal cells, the polymorphisms in IL - 1β +3953 from peripheral venous blood and the contents of immunoglobulins in serum, including immunoglobulin G , immunoglobulin A, immunoglobulin M.Methods1. Study populationCase group was consisted of 25 patients with severe periodontitis and 11 patients with mild to moderate periodontitis. 36 subjects age - and gender -matched with healthy periodontal conditions were enrolled. The subjects were excluded if they smoked and received professional teeth cleaning or systemic medication, including any drugs, during the 3 months prior to the study. All subjects signed an informed consent to participate in the study.2. Measurement of clinical periodontal statusClinical parameters were measured and recorded by a single examiner, which included plaque index (PLI) , bleeding on probing (BOP) , probing depth (PD)and clinical attachment loss(CAL).3. Sample collectionCells were collected from mucosa of both cheeks with sterile cytologicalbrushes, then placed into sterile eppendorf tubes containing 1. 5ml PBS(PH 7.3). 3ml of peripheral blood from each subjects by venepuncture was obtained, in which 1ml was putted into heparinised tubes and the remainders was centrifuged to get serum. All samples were frozen for later analysis.4. Immunohistochemical analysis of IL - 1βBuccal cells were centrifuged, fixed in 10% formaldehyde for 15 min and dropped on glass. The expression of IL - 1β in buccal cells was examined by u-sing SABC immunohistochemical technique. With optical microscope 100 cheek cells were counted where cells scattered uniformly and analyzed the levels of positive expression of IL - 1β.5. Examination of the polymorphism in IL - 1β +3953Genomic DNA from peripheral venous blood was extracted with saturant sodium chloride, amplified with IL - 1βprimers then digested with Taq I restriction endonuclease. The polymorphism in IL - 1β+3953 was examined after electrophoresis on a 12% polyacrylamide gel and ethidium bromide staining.6. Measurement of the immunoglobulins in serumTo measure the contents of immunoglobulins in serum including IgG, IgA, IgM with tempo turbidimetry.7. Statistical analysisStatistical tests were performed by x2 test , independent - samples T test, multiple linear regression and Pearson correlativity based on the types of data.Results1. IL -1βwas expressed with different levels in all subject cheek cells.. Highly statistically significant difference was detected among the severe periodontitis , mild to moderate periodontitis and healthy groups. Subdividing X2 test showed that significant differences existed not only between the case and control groups but also among the patients with different severity of periodontitis.2. Homozygous for allele 1 was the main genotype in all subjects. Heterozygous for allele 1/2 was found in one (9. 09 % ) of the patients with mild to moderate periodontitis, and 3(12 % )of the 25 severe periodontitis. There wasno homozygous for allele 2 observed. No significant difference in the distribution of genotypes was detected between patients of the three disease severities or between patients and controls. Further subdividing X2 test showed that a significant difference existed between severe periodontitis and healthy subjects.3. Multiple linear regression confirmed that CAL and PD positively associated with the expression of IL -1β and no relationships were found between PLI, BOP, polymorphisms in IL - 1β +3953 and the levels of IL -1β.4. The mean contents of IgA and IgM from serum of patients was 2.908 ± 0.993 g/L,1.207 ±0. 525 g/L respectively, while 2. 566 ± 1.026 g/L, 1. 170± 0. 556 g/L in controls. Independent - T test revealed that no significant difference was found between case and control groups. Though there was an increase in the mean content of IgG in periodontitis, it failed to reach significance.5. Pearson correlativity analysis showed that no significant associations were observed between the amounts of IgG, IgA, IgM in serum and the levels of IL-1β expressed in cheek cells or several clinical parameters.Conclusions1. The level of IL - 1β expressed in buccal cells positively associated with PD and CAL, which reveals that body local cellular immune response participates in the onset and development of periodontitis and the intensity of response reflects the severity of disease.2. No relationship between the IL-1β+3953 allele 2 and the expression of IL -1β was found, but the frequency of this genotype in severe periodontitis drastically increased. So it is presumed that this specific genotype made periodontal tissues susceptible to pathogenic bacteria.3. Though the content of IgG in serum of patients compared to healthy controls trended towards increase, this difference failed to reach significance. In addition, the contents of IgG,IgA and IgM in serum were not associated with the expression of IL - 1β or with several clinical parameters. The results showed that local cellular immune response played a more significant role than systematic hu-...
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