T‐cell‐receptor gene usage of Actinobacillus actinomycetemcomitans‐reactive periodontal CD4⁺ T cells from localized juvenile periodontitis patients and human peripheral blood leukocyte‐reconstituted NOD/SCID mice

Abstract

We investigated the variable Valpha and Vbeta gene usage of Actinobacillus actinomycetemcomitans-reactive periodontal CD4+ T cell receptors (TCR) from: (i) four A. actinomycetemcomitans-infected localized juvenile periodontitis (LJP) patients, (ii) four groups of A. actinomycetemcomitans-inoculated NOD/SCID mice engrafted with individual LJP-derived HuPBL and (iii) HuPBL samples of four LJP patients and two healthy control subjects, by quantitative PCR analyses. The results show that: (i) the majority of the TCR genes (82.5% of Valpha and 91.1% of Vbeta) used by periodontal CD4+ T cells in A. actinomycetemcomitans-inoculated HuPBL-engrafted NOD/SCID mice overlap with those used by local periodontal T cells in LJP patients, (ii) although A. actinomycetemcomitans-reactive periodontal CD4+ TCR repertoire is relatively widespread, there are a few dominant genes shared by the LJP patients, suggesting a limited number of antigens or epitopes commonly recognized and (iii) A. actinomycetemcomitans likely lacks superantigenic characteristics. These results suggest A. actinomycetemcomitans-associated human CD4+ T cell repertoire established in HuPBL-NOD/SCID mice provides a useful approach to study specific aspects of immune-parasite interactions in the periodontium.

Mixed Periodontal Th1-Th2 Cytokine Profile in Actinobacillus actinomycetemcomitans -Specific Osteoprotegerin Ligand (or RANK-L)- Mediated Alveolar Bone Destruction In Vivo

“…Eighty-nine female NOD-SCID mice, 8 to 9 weeks old, were obtained from the breeding suites of the animal colony and housed in a specific-pathogen-free unit. The experimental protocols were described in detail previously (8,25), and the levels of individual HuPBL engraftment in the mice were comparable (Ն30%) to those reported in our previous studies.…”

“…These results suggest the critical role of microorganism-reactive human CD4 ϩ T cells in periodontal pathogenesis. Further, a majority of the T-cell receptor (TCR) genes used by periodontal CD4 ϩ T cells in these mice overlap (83% of TCR V␣; 91% of TCR V␤) with those used by periodontal T cells in LJP patients (8). This suggests that a pathogen-associated human immune repertoire can be established in these mice.…”

“…However, when HuPBL samples from N1 and N2 were used, there was very little periodontal inflammatory infiltrate and alveolar bone loss detected by 8 weeks (26). Due to this factor, periodontal and cervical lymph node-derived CD4 ϩ T cells were collected from a pool of 10 to 14 A. actinomycetemcomitans-inoculated N-HuPBL-NOD-SCID mice (engrafted with autologous HuPBL from N1 or N2 [26]) as the cellular sources for PCR analyses (8). This was further supported in our previous study (26), where periodontal CD4 ϩ T cells isolated from A. actinomycetemcomitans-inoculated NHuPBL-NOD-SCID mice showed very little OPGL expression by fluorescence-activated cell sorter analysis, in contrast to those isolated from A. actinomycetemcomitans-inoculated HuPBL-NOD-SCID mice.…”

“…Briefly, four LJP patients [LJP1 to LJP4; mean age, 21 Ϯ 4.4 years] and two disease-free healthy subjects [N1 and N2; ages, 19 and 22 years] had been described previously (8,26). Informed consent was obtained from all of the patients, and all protocols were approved by the human ethics and animal experimentation committees of the University of Western Ontario.…”

“…We have established a humanized mouse model to study periodontal immune cell-parasite interactions (8,25,26) where (i) nonobese diabetic (NOD)-SCID mice can be reconstituted by human peripheral blood leukocytes (HuPBL; 30 to 60% chimerism); (ii) activated human CD4 ϩ T cells are essential mediators of alveolar bone destruction; (iii) oral inoculation of HuPBL-NOD-SCID mice (which received HuPBL engraftments from LJP subjects) with A. actinomycetemcomitans leads to increased expression of osteoprotegerin ligand (OPGL, or RANK-L), a key mediator of osteoclastogenesis and osteoclast activation, by periodontal CD4 ϩ T cells; and (iv) inhibition of OPGL via antagonistic osteoprotegerin (OPG) significantly reduces alveolar bone destruction after bacterial infection. These results suggest the critical role of microorganism-reactive human CD4 ϩ T cells in periodontal pathogenesis.…”