Selective Blockade of Voltage-Gated Potassium Channels Reduces Inflammatory Bone Resorption in Experimental Periodontal Disease

Authors

  • Paloma Valverde,

    Corresponding author
    1. Department of Oral and Developmental Biology, Harvard Medical School and Harvard School of Dental Medicine, Boston, Massachusetts, USA
    2. USDA Human Nutrition Research Center on Aging at Tufts University, Tufts University, Boston, Massachusetts, USA
    • Address reprint requests to: Paloma Valverde, PhD USDA Human Nutrition Research Center on Aging Tufts University 711 Washington Street Room 626 Boston, MA 02111, USA
    Search for more papers by this author
  • Toshihisa Kawai,

    1. Department of Oral and Developmental Biology, Harvard Medical School and Harvard School of Dental Medicine, Boston, Massachusetts, USA
    2. Department of Immunology, The Forsyth Institute, Boston, Massachusetts, USA
    Search for more papers by this author
  • Martin A Taubman

    1. Department of Oral and Developmental Biology, Harvard Medical School and Harvard School of Dental Medicine, Boston, Massachusetts, USA
    2. Department of Immunology, The Forsyth Institute, Boston, Massachusetts, USA
    Search for more papers by this author

  • The authors have no conflict of interest.

  • Part of this work was presented at the 24th annual meeting of the American Society of Bone and Mineral Research, San Antonio, Texas, September 20–24, 2002.

Abstract

The effects of the potassium channel (Kv1.3) blocker kaliotoxin on T-cell-mediated periodontal bone resorption were examined in rats. Systemic administration of kaliotoxin abrogated the bone resorption in conjunction with decreased RANKL mRNA expression by T-cells in gingival tissue. This study suggests a plausible therapeutic approach for inflammatory bone resorption by targeting Kv1.3.

Introduction: Kv1.3 is a critical potassium channel to counterbalance calcium influx at T-cell receptor activation. It is not known if Kv1.3 also regulates RANKL expression by antigen-activated T-cells, and consequently affects in vivo bone resorption mediated by activated T-cells.

Materials and Methods:Actinobacillus actinomycetemcomitans 29-kDa outer membrane protein-specific Th1-clone cells were used to evaluate the expression of Kv1.3 (using reverse transcriptase-polymerase chain reaction [RT-PCR] and Western blot analyses) and the effects of the potassium channel blocker kaliotoxin (0–100 nM) on T-cell activation parameters ([3H]thymidine incorporation assays and ELISA) and expression of RANKL and osteoprotegerin (OPG; flow cytometry, Western blot, and RT-PCR analyses). A rat periodontal disease model based on the adoptive transfer of activated 29-kDa outer membrane protein-specific Th1 clone cells was used to analyze the effects of kaliotoxin in T-cell-mediated alveolar bone resorption and RANKL and OPG mRNA expression by gingival T-cells. Stimulated 29-kDa outer membrane protein-specific Th1 clone cells were transferred intravenously on day 0 to all animals used in the study (n = 7 animals per group). Ten micrograms of kaliotoxin were injected subcutaneously twice per day on days 0, 1, 2, and 3, after adoptive transfer of the T-cells. The control group of rats was injected with saline as placebo on the same days as injections for the kaliotoxin-treated group. The MOCP-5 osteoclast precursor cell line was used in co-culture studies with fixed 29-kDa outer membrane protein-specific Th1-clone cells to measure T-cell-derived RANKL-mediated effects on osteoclastogenesis and resorption pit formation assays in vitro. Statistical significance was evaluated by Student's t-test.

Results: Kaliotoxin decreased T-cell activation parameters of 29-kDa outer membrane protein-specific Th1 clone cells in vitro and in vivo. Most importantly, kaliotoxin administration resulted in an 84% decrease of the bone resorption induced in the saline-treated control group. T-cells recovered from the gingival tissue of kaliotoxin-treated rats displayed lower ratios of RANKL and OPG mRNA expression than those recovered from the control group. The ratio of RANKL and osteoprotegerin protein expression and induction of RANKL-dependent osteoclastogenesis by the activated T-cells were also markedly decreased after kaliotoxin treatments in vitro.

Conclusion: The use of kaliotoxin or other means to block Kv1.3 may constitute a potential intervention therapy to prevent alveolar bone loss in periodontal disease.

Ancillary