José R. Gonzales

Replication of the association of chromosomal region 9p21.3 with generalized aggressive periodontitis (gAgP) using an independent case-control cohort

BackgroundThe human chromosomal region 9p21.3 has been shown to be strongly associated with Coronary Heart Disease (CHD) in several Genome-wide Association Studies (GWAS). Recently, this region has also been shown to be associated with Aggressive Periodontitis (AgP), strengthening the hypothesis that the established epidemiological association between periodontitis and CHD is caused by a shared genetic background, in addition to common environmental and behavioural risk factors. However, the size of the analyzed cohorts in this primary analysis was small compared to other association studies on complex diseases. Using our own AgP cohort, we attempted to confirm the described associations for the chromosomal region 9p21.3.MethodsWe analyzed our cohort consisting of patients suffering from the most severe form of AgP, generalized AgP (gAgP) (n = 130) and appropriate periodontally healthy control individuals (n = 339) by genotyping four tagging SNPs (rs2891168, rs1333042, rs1333048 and rs496892), located in the chromosomal region 9p21.3, that have been associated with AgP.ResultsThe results confirmed significant associations between three of the four SNPs and gAgP. The combination of our results with those from the study which described this association for the first time in a meta-analysis of the four tagging SNPs produced clearly lower p-values compared with the results of each individual study. According to these results, the most plausible genetic model for the association of all four tested SNPs with gAgP seems to be the multiplicative one.ConclusionWe positively replicated the finding of an association between the chromosomal region 9p21.3 and gAgP. This result strengthens support for the hypothesis that shared susceptibility genes within this chromosomal locus might be involved in the pathogenesis of both CHD and gAgP.

B7-H1 and B7-DC receptors of oral squamous carcinoma cells are upregulated by Porphyromonas gingivalis.

The up-regulation of the B7-H1 receptors in host cells might influence the chronicity of inflammatory disorders that frequently precede the development of human cancers. B7-H1 expression has been detected in the majority of human cancers, leading to anergy and apoptosis of activated T cells, and enabling tumor cells to overcome host response. Porphyromonas gingivalis (P. gingivalis), a putative periodontal pathogen, is an etiologic agent of periodontitis and expresses a variety of virulence factors. In this study, the expression of B7-H1 and B7-DC receptors on squamous cell carcinoma cells SCC-25 and BHY and primary human gingival keratinocytes (PHGK) was analyzed after infection with two virulent P. gingivalis strains in vitro. After 48h, the cells were stained with antibodies for human B7-H1 and B7-DC and further analyzed by flow cytometry. RNA was extracted and gene expression of B7-H1 or B7-DC was quantified by real time PCR. After infection with P. gingivalis, both B7-H1 and B7-DC receptors were up-regulated. The mean fluorescence intensity (MFI) increased from 4.5 to 9.9 (B7-H1) and from 6.9 to 15.0 (B7-DC) (p<0.05, respectively) in SCC-25 cells. PHGK showed an increase from 4.8 to 12.4 (B7-H1) and from 5.5 to 15.6 (B7-DC) (p<0.05, respectively). Streptococcus salivarius K12, a commensal bacterium, caused no up-regulation. After 24h, the expression of B7H1 and B7-DC mRNA in infected cells, normalized to GAPDH and in relation to non-infected cells, was 6.4 fold (B7-H1) and 8.6 fold (B7-DC) higher. In PHGK B7-H1/DC mRNA expression increased 8.2 fold (B7-H1) and 5.9 fold (B7DC) (p<0.05) respectively. The results of the study demonstrate that in contrast to S. salivarius K12 virulent P. gingivalis strains are able to induce the expression of the B7-H1 and B7-DC receptors in squamous carcinoma cells and human gingival keratinocytes, which might facilitate immune evasion by oral cancers.

Production of Interleukin-13 is Influenced by the Interleukin-4 −34TT and −590TT Genotype in Patients with Aggressive Periodontitis

Aggressive periodontitis (AgP) is a specific form of periodontal disease, with rapid destruction of the tissues supporting the teeth in otherwise young healthy individuals. We recently showed a higher frequency of the interleukin‐4 (IL‐4) −34TT and −590TT genotype in AgP patients compared to controls (P < 0.05). Herein, we demonstrated that this specific IL‐4 genotype exerts its function by increasing expression of IL‐4 and STAT6, and producing higher concentrations of IL‐4 in activated CD4+ cells of patients with AgP. In the present study, we investigated the effects of the IL‐4‐specific genotype on IL‐13, IL‐2 and IFN‐γ expression and production in activated CD4+ cells of patients with AgP and healthy controls. Results revealed higher IFN‐γ and IL‐2 expression and significantly increased IL‐13 production in the cells of the patients who were homozygous for the −34T and −590T alleles in comparison with the patients who were homozygous for the −34C and −590C alleles (P < 0.05). Results of controls with the −34C and −590C alleles were similar to those of AgP with the same genotype. To our knowledge, the present study is the first to show an effect of the −34TT and −590TT genotype on IL‐13 production. There is an increased production of IL‐13 by the T cells of aggressive periodontitis patients with the IL‐4 genotype.

T‐ and B‐cell subsets in periodontitis

A large amount of information is available, in the medical literature, on the molecular and immunological mechanisms in which T- and B-cells are involved in the pathogenesis of inflammatory diseases. This review attempts to describe the most important features of the T-cell subsets and their cytokine networks in periodontitis, including the interaction of pathogens with different cell subsets and their gene-expression profiles. Additionally, the known interactions of T- and B-cell subsets in periodontitis are described. The purpose of this article was to provide an overview of the cell interactions and cytokine networks specifically involved in the pathogenesis of periodontitis, and models and paradigms from recent research in this area are presented. However, the review of the literature also revealed that relatively little is known about the genetic or structural factors that confer cross-reactivity of natural and/or autoreactive antibodies in the immunopathogenesis of periodontitis. Pathogens, in turn, are continuously evolving and creating mechanisms to evade immunological reactions controlled and modulated by T- and B-cells.

The interleukin-4 -34TT and -590TT genotype is correlated with increased expression and protein production in aggressive periodontitis.

Aggressive periodontitis (AgP) is a severe periodontal disease characterized by rapid destruction of the tissues supporting the teeth in otherwise healthy individuals. The frequency of the interleukin-4 homozygous -34TT and -590TT genotype was increased in patients in comparison with controls. This study aimed to test the functional effect of this specific genotype in AgP patients by analyzing gene expression of IL-4 and STAT6, and protein concentration of IL-4, in activated CD4+ T cells. Results revealed an increased IL-4 and STAT6 expression and IL-4 production in the cells of the patients who were homozygous for the -34T and -590T alleles in comparison with the patients who were homozygous for the -34C and -590C alleles (p<0.05). These findings demonstrate that the IL-4 -34TT and -590TT genotype has a functional effect on T helper (Th) cells of patients with AgP, inducing increased expression of IL-4 and STAT6, and increased production of IL-4.