Tariq, Maheen
(2022)
Intra-subject investigation into the
role of dental plaque induced IL-8, IL-6
and IL-1α expression and its association
with the subgingival plaque
microbiome.
Masters thesis, Universiti Sains Malaysia.
Abstract
Aims: The study aims to evaluate the subgingival plaque microbiome
composition and measure the GCF level of the IL-8, IL-6, and IL-1α of healthy and
periodontitis sites in the same periodontitis subject. The study also explored the
association between subgingival plaque composition and GCF levels of IL-8, IL-6,
and IL-1α at periodontitis and healthy sites.
Materials and methods: This study
included 34 periodontitis subjects to collect the subgingival plaque and GCF samples
from the periodontitis and healthy sites. The extracted DNA from dental plaque was
sent to Illumina lab for 16s rRNA metagenomics. The V₃ and V₄ region of 16s RNA
were amplified. The library was sequenced with MiSeq System, and data was analysed
using MiSeq Reporter software (Illumina, San Diego, CA). After, quality filtering
313480 sequences were obtained and arranged in OTU based on 97% threshold. The
GCF samples were analysed using ELISA to measure the level of IL-8, IL-6 and IL-
1α. The optical density was determined, and standard curve was generated using a
four-parameter logistic curve fit.
Results: The analysis of 16s rRNA revealed that
periodontitis sites showed a higher species diversity than healthy sites. Moreover, there
was no apparent clustering of healthy and periodontitis samples. Total 19 phylum, 142
genera, and 56 species were detected. The ELISA results show a trend of higher IL-8
and IL-6 concentrations in periodontitis sites and higher IL-1 concentrations in healthy
sites. However, the differences between healthy and periodontitis sites were not
statistically significant. Moreover, there was also a trend of positive and a negative
correlation between periodontal parameters (PPD, CAL, and BOP) with IL-8, IL-6,
and IL-1α. However, these findings were not statistically significant. The correlation between IL-8, IL-6, and IL-1α and bacterial species was also investigated. Our results
show a statistically significant correlation (a mix of negative and positive correlation)
between some bacteria species and cytokines (IL-8, IL-6 and IL-1α). For example, at
the periodontitis site, IL-8 showed a statistically significant strong positive correlation
with Bacillus thermoamylovorans.
Conclusion: These findings suggests that certain
microbiome may possibly cause the host immune system to secrete pro-inflammatory
cytokines such as IL-8, IL-6, and IL-1α. Moreover, disease-related bacteria such as
Phlyum (Spirochaetes, TM7 and Synergestetes), genus (Porphyromonas, Filifactor,
and Peptococcus) and species (Prevotella intermedia, Prevotella copri, Prevotella
nanceiensis, and Treponema socranskii) may be found abundantly in healthy sites and
may help in the shift from healthy to periodontal disease.
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