Heritability in generalized aggressive periodontitis : microbiological, immunological and preventive aspects = Hereditariedade na periodontite agressiva generalizada: aspectos microbiológicos, imunológicos e preventivos

Generalized aggressive periodontitis (GAgP) is a multifactorial disease caused by an unbalance between the host response e the biofilm aggression. It is characterized by the familial aggregation of cases, probably associated with the sharing of susceptibility aspects between family member, what could increase the risk to GAgP descendants to develop GAgP. In this context, the present report describes three different studies: the first aiming to characterize the microbiome, as well its association to the host response, in GAgP subjects and their children; the second study aiming to evaluate the effective of plaque control in altering the pathogenic subgingival condition identified in GAgP descendants; the third aiming to evaluate the efficiency of Triclosan-containing toothpaste as an adjunctive therapy to control the precocious alteration demonstrated in GAgP descendants. In the first study, 15 GAgP parents with at least a child between 6-12 years old and 15 health parents with at least one child between 6-12 years old were selected. The clinical examination and the collection of subgingival biofilm and gingival crevicular fluid (GCF) were performed for all subjects. The bacterial DNA of the subgingival biofilm was extracted, the 16S rRNA was sequenced using the Illumina MiSeq platform and bioinformatic tools were used to analyze the data. The gingival crevicular fluid was analyzed with the Luminex MAGPIX technology for the identification of interferon (IFN)γ, and tumor necrosis factor (TNF)-α, interleukin (IL)-10, IL-4, IL-1β, IL-17, IL-6, IL-8 levels. Children from GAgP parents presented the worst clinical condition as well as a more pathogenic and dysbiotic microbiome than children from healthy parents. A strong correlation was observed between the parent microbiome and his child microbiome. Differences in the cytokines’ levels were only observed in parents with GAgP parent presenting lower levels of IFN-γ, IL-10, and IL-17. Despite no differences in the cytokine levels, children from GAgP parents presented alteration in the host-bacterial interactions and demonstrated a similar pattern to their parents. In the second study, 18 children (6-12 years old) from GAgP parents and 18 children from periodontally healthy parents were included in a plaque control program for 3 months. All subjects were periodontally examined and subgingival biofilm and gingival crevicular fluid (GCF) were collected at baseline and after 3 months of strict plaque control. Next-generation sequencing and bioinformatic tools were used to evaluate the subgingival microbiome and the Luminex/MAGPIX platform was used for the inflammatory analysis in GCF. The Linear Discriminant Analysis of Morisita-Horn index demonstrated two massive clusters separating children from AgP parents from children from healthy parents (Adonis test, p=0.014), demonstrating a significant impact of parental periodontitis on the microbiome of their descendants. A more pathogenic microbiome associated with more intense host-bacterial interactions and worst clinical condition was identified in children from GAgP parents. The dysbiotic microbiome of GAgP descendants showed a strong resilience against shifting after plaque control, maintaining the diversity and the richness of disease-associated species even after the clinical benefits achieved. In addition, plaque control was not sufficient to alter the pattern of host-bacterial interaction in the subgingival environment. In the third study, 15 children from GAgP parents and 15 children from periodontally healthy parents were included in this cross-over placebo study. Children were randomly allocated into Triclosan or Placebo groups to participate in the first phase of the study. Initially, all children participate in a washout period of 15 days using only the placebo toothpaste and posteriorly they started to use the elected toothpaste for 45 days. After the first phase, they repeated the period of 15 days of washout using only the placebo toothpaste. The groups were crossed, and the children used the other paste for more 45 days. In each phase, clinical examination and saliva, GCF and subgingival biofilm collection were performed at baseline and 45 days. The levels of IFN-γ, IL-4, IL-10, IL-1β, IL-17, and TNF-α were analyzed by Luminex/MAGpix platform and subgingival and salivary periodontal pathogens’ levels by qPCR. At baseline, children from AgP parents presented higher levels of the gingival index (GI), plaque index (PI), and bleeding on probing (BoP), a higher concentration of Aggregatibacter actinomycetemcomitans (Aa) in saliva and subgingival biofilm, and lower levels of INF-ɣ, IL-4, IL-17 in the GCF. Placebo therapy only reduced PI, in both groups. Triclosan toothpaste reduced PI, as well as GI, in both groups. Moreover, Triclosan promoted the reduction of BoP and PPD, Aa salivary levels and IL-1β in GAgP group. In Health group, Triclosan promoted a reduction of INF-ɣ and IL-4. In conclusion, the microbiome and the host-bacterial interaction were altered in GAgP parent and their descendants and a strong impact of the parents’ periodontal condition in their children periodontal status was demonstrated. The dysbiosis was associated with more intense species cytokines correlations and higher clinical inflammation. The plaque control was not able to change the more pathogenic subgingival environment of GAgP descendants, that demonstrated a strong resilience to subgingival microbial shifting after strict plaque control, highlighting the higher risk for disease development. Furthermore, Triclosan dentifrice demonstrated to be more efficient than placebo toothpaste to control the more pathogenic profile demonstrate in GAgP, by reducing the bleeding on probing, probing depth, salivary Aa and IL-1β, in children from GAgP parents.