Expression of receptor activator of nuclear factor-kappaB ligand by B cells in response to oral bacteria.
BACKGROUND
We investigated receptor activator of nuclear factor-kappaB ligand (RANKL) expression by B lymphocytes during early and late aspects of the immune response to Aggregatibacter actinomycetemcomitans, a gram-negative, anaerobic bacterium associated with aggressive periodontal disease.


METHODS
Expression of messenger RNA transcripts (tumor necrosis factor-alpha, Toll-like receptors 4 and 9, interleukins 4 and 10, and RANKL) involved in early (1-day) and late (10-day) responses in cultured rat splenocytes was examined by reverse transcription-polymerase chain reaction (RT-PCR). The immune cell distribution (T, B, and natural killer cells and macrophages) in cultured rat splenocytes and RANKL expression in B cells were determined by flow cytometric analyses. B-cell capacity for induction of osteoclast differentiation was evaluated by coculture with RAW 264.7 cells followed by a tartrate-resistant acid phosphatase (TRAP) activity assay.


RESULTS
The expression levels of interleukins 4 and 10 in cultured cells were not changed in the presence of A. actinomycetemcomitans until cultured for 3 days, and peaked after 7 days. After culture for 10 days, the percentages of B and T cells, the overall RANKL messenger RNA transcripts, and the percentage of RANKL-expressing immunoglobulin G-positive cells were significantly increased in the presence of A. actinomycetemcomitans. These increases were considerably greater in cells isolated from A. actinomycetemcomitans-immunized animals than from non-immunized animals. RAW 264.7 cells demonstrated significantly increased TRAP activity when cocultured with B cells from A. actinomycetemcomitans-immunized animals. The addition of human osteoprotegerin-Fc to the culture significantly diminished such increases.


CONCLUSIONS
This study suggests that B-lymphocyte involvement in the immune response to A. actinomycetemcomitans through upregulation of RANKL expression potentially contribute to bone resorption in periodontal disease.
Han
X
X
Department of Immunology, The Forsyth Institute, Boston, MA 02115-3799, USA.
Lin
X
X
Seliger
A R
AR
Eastcott
J
J
Kawai
T
T
Taubman
M A
MA
D000135:Acid Phosphatase / Q000032:analysis / Q000037:antagonists & inhibitors; D016976:Aggregatibacter actinomycetemcomitans / Q000276:immunology*; D000818:Animals; D000921:Antibody-Producing Cells / Q000276:immunology; D001402:B-Lymphocytes / Q000276:immunology*; D015415:Biomarkers / Q000032:analysis; D002454:Cell Differentiation / Q000502:physiology; D002460:Cell Line; D002478:Cells, Cultured; D018920:Coculture Techniques; D006801:Humans; D007141:Immunoglobulin Fc Fragments / Q000276:immunology; D007074:Immunoglobulin G / Q000032:analysis; D016753:Interleukin-10 / Q000032:analysis; D015847:Interleukin-4 / Q000032:analysis; D007527:Isoenzymes / Q000032:analysis / Q000037:antagonists & inhibitors; D007694:Killer Cells, Natural / Q000276:immunology; D008264:Macrophages / Q000276:immunology; D009055:Mouth / Q000276:immunology / Q000382:microbiology*; D010010:Osteoclasts / Q000502:physiology; D053244:Osteoprotegerin / Q000494:pharmacology; D053245:RANK Ligand / Q000032:analysis* / Q000187:drug effects; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D013154:Spleen / Q000166:cytology; D013601:T-Lymphocytes / Q000276:immunology; D000071681:Tartrate-Resistant Acid Phosphatase; D013997:Time Factors; D051197:Toll-Like Receptor 4 / Q000032:analysis; D051217:Toll-Like Receptor 9 / Q000032:analysis; D014409:Tumor Necrosis Factor-alpha / Q000032:analysis
D015415:Biomarkers; D007141:Immunoglobulin Fc Fragments; D007074:Immunoglobulin G; D007527:Isoenzymes; D053244:Osteoprotegerin; D053245:RANK Ligand; D012333:RNA, Messenger; C506032:Tnfrsf11b protein, rat; D051197:Toll-Like Receptor 4; D051217:Toll-Like Receptor 9; D014409:Tumor Necrosis Factor-alpha; D016753:Interleukin-10; D015847:Interleukin-4; D000135:Acid Phosphatase; D000071681:Tartrate-Resistant Acid Phosphatase